Laser based display method and system

The present invention relates to display technology. More particularly, various embodiments of the present invention provide projection display systems.

In projection display systems, one or more laser diodes and/or LEDs are used as light sources to show images. In one set of embodiments, projector systems provided by the present invention employ blue and/or green lasers fabricated using gallium nitride-containing materials. In another set of embodiments, the invention provides a projection system having a digital lighting processing engine. The digital lighting processing engine is illuminated by a blue laser device and/or a green laser device. In certain embodiments, the invention provides a 3D display system, but other embodiments exist.

<p>Large displays are becoming more and more popular and are expected to become more popular in the next few years. Because, with the lower price of LCD displays, television and digital advertisements are also becoming more and more common at gas stations, shopping malls and coffee shops. The substantial growth of large displays (eg, 40-inch TVs) in recent years has exceeded, for example, 40%, and consumers have become accustomed to larger displays in notebooks and PCs. Displays within consumer handheld electronics remain small (greater than 3 inches) as more display content (e.g., TV, Internet and video) becomes available via handheld devices and have space and power for keyboards, cameras and other features.</p><p>Against this background, an improved system for displaying images and/or video was therefore desired.</p>

<p>The present invention relates to display technology. More particularly, various embodiments of the present invention provide projection display systems. In projection display systems, one or more laser diodes are used as light sources to show images. In one set of embodiments, projector systems provided by the present invention employ blue and/or green lasers fabricated using gallium nitride-containing materials. In another set of embodiments, the invention provides a projection system having a digital lighting processing engine. The digital lighting processing engine is illuminated by a blue laser device and/or a green laser device. Other embodiments also exist.</p><p>According to embodiments, the invention provides a projection system. The projection system includes an interface for video reception. The system also includes an image processor that processes the video. The system includes a light source that includes multiple laser diodes. The plurality of laser diodes includes blue laser diodes. Blue laser diodes are fabricated on non-polarized oriented gallium nitride material. The system includes a power source electrically connected to the light source.</p><p>According to another embodiment, the invention provides a projection system. The system includes an interface for video reception. The system also includes an image processor that processes the video. The system includes a light source that includes multiple laser diodes. The plurality of laser diodes includes blue laser diodes. Blue laser diodes are fabricated on semipolar oriented gallium nitride material. The system also includes a power source electrically connected to the light source.</p><p>According to embodiments, the present invention provides a projection device. A projection device includes a housing having an opening. The device also includes an input interface for receiving one or more image frames. The device includes a video processing module. Additionally, the device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of the green laser diode is about 490 nm to 540 nm. Red lasers can be made from AlInGaP. The laser source is configured to generate a laser beam by combining outputs from the blue, green and red laser diodes. The apparatus also includes a laser driver module connected to the laser source. A laser driver module generates three drive currents based on pixels from one or more image frames. Each of the three drive currents is adapted to drive a laser diode.</p><p>The device also includes a micro-electro-mechanical system (MEMS) scanning or flying mirror. A micro-electro-mechanical system (MEMS) scanning or flying mirror is configured to project a laser beam through an aperture to a specific location, resulting in a single picture. A complete image is formed by rastering the pixels in two dimensions. The apparatus includes an optical member located near the laser source. The optical member is adapted to direct the laser beam to the MEMS scanning mirror. The apparatus includes a power source electrically connected to the laser source and the MEMS scanning mirror.</p><p>According to embodiments, the present invention provides a projection device. A projection device includes a housing having an opening. The device also includes an input interface for receiving one or more image frames. The device includes a video processing module. Additionally, the device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of green laser diodes is about 490 nm to 540 nm. In this embodiment, the blue and green laser diodes share the same substrate. Red lasers can be made from AlInGaP. The laser source is configured to generate a laser beam by combining outputs from the blue, green and red laser diodes. The apparatus also includes a laser driver module connected to the laser source.</p><p>A laser driver module generates three drive currents based on pixels from one or more image frames. Each of the three drive currents is adapted to drive a laser diode. The device also includes a MEMS scanning or flying mirror. A MEMS scanning or flying mirror is configured to project a laser beam through an aperture to a specific location, resulting in a single picture. A complete image is formed by rastering the pixels in two dimensions. The apparatus includes an optical member located near the laser source, the optical member adapted to direct the laser beam to the MEMS scanning mirror. The apparatus includes a power source electrically connected to the laser source and the MEMS scanning mirror.</p><p>According to embodiments, the present invention provides a projection device. A projection device includes a housing having an opening. The device also includes an input interface for receiving one or more image frames. The device includes a video processing module. Additionally, the device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of green laser diodes is about 490 nm to 540 nm. Red lasers can be made from AlInGaP. In this embodiment, two or more of the different colored lasers are packaged in the same enclosure. In this co-package embodiment, the outputs from the blue, green and red laser diodes are combined into a single beam. The apparatus also includes a laser driver module connected to the laser source. A laser driver module generates three drive currents based on pixels from one or more image frames. Each of the three drive currents is adapted to drive a laser diode. The device also includes a micro-electro-mechanical system (MEMS) scanning or flying mirror. A micro-electro-mechanical system (MEMS) scanning or flying mirror is configured to project a laser beam through an aperture to a specific location, resulting in a single picture. A complete image is formed by rastering the pixels in two dimensions. The apparatus includes an optical member located near the laser source, the optical member adapted to direct the laser beam to the MEMS scanning mirror. The apparatus includes a power source electrically connected to the laser source and the MEMS scanning mirror.</p><p>According to another embodiment, the invention provides a projection device. The device includes a housing having an opening. The device includes an input interface for receiving one or more image frames. The device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of the green laser diode is about 490 nm to 540 nm. Red lasers can be made from AlInGaP. The laser source is configured to generate a laser beam by combining outputs from the blue, green and red laser diodes. The device includes a Digital Light Processing (DLP) chip. A digital light processing (DLP) chip includes a digital mirror device. A digital mirror device includes a plurality of mirrors, each mirror corresponding to one or more pixels of one or more image frames. The apparatus includes a power supply electrically connected to a laser source and a digital light processing chip. Many variations of this embodiment are possible, for example, in one embodiment the green and blue laser diodes share the same substrate, or two or more of the different colored lasers can be housed in the same package. In this same-package embodiment, the outputs from the blue, green and red laser diodes are combined into a single beam.</p><p>According to another embodiment, the invention provides a projection device. The device includes a housing having an opening. The device includes an input interface for receiving one or more image frames. The device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of green laser diodes is about 490 nm to 540 nm. Red lasers can be made from AlInGaP. The device includes a digital light processing chip (DLP). A digital light processing chip (DLP) contains three digital mirror devices. Each digital mirror device includes multiple mirrors. Each mirror corresponds to one or more pixels of one or more image frames. The color beams are each projected onto a digital mirror device. The apparatus includes a power supply electrically connected to a laser source and a digital light processing chip. Many variations of this embodiment are possible, for example, in one embodiment green and blue laser diodes share the same substrate, or two or more of the different colored lasers can be housed in the same package. . In this co-package embodiment, the outputs from the blue, green and red laser diodes are combined into a single beam.</p><p>As an example, the color wheel may include phosphor materials that change the color of light emitted from the light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source and a red light source. The color wheel includes grooves for blue light and phosphors that include regions for converting blue light to green light. In operation, a blue light source (eg, a blue laser diode or a blue LED) provides blue light through the grooves to excite green light from the phosphor-containing regions. A red light source separately provides red light. Green light from the phosphor can be transmitted through the color wheel or reflected from the color wheel. In either case, green light is collected by optics and redirected to the microdisplay. Blue light passing through the groove is also directed to the microdisplay. The blue light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. Alternatively, a green laser diode may be used instead of a blue laser diode using phosphor to emit green light. It is understood that other combinations of colored light sources and their color wheel are possible.</p><p>As another example, the color wheel may include multiple phosphor materials. For example, a color wheel can include both green and red phosphors combined with a blue light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source. The color wheel includes a groove for blue laser light and two phosphor-containing regions for conversion of blue light to green light and blue light to red light, respectively. In operation, a blue light source (eg, a blue laser diode or blue LED) provides blue light through the grooves and excites green and red light from the phosphor-containing regions. Green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, green and red light is collected by optics and redirected to the microdisplay. The blue light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. It is understood that other combinations of colored light sources and their color wheel are possible.</p><p>As another example, a color wheel may include blue phosphor material, green phosphor material, and red phosphor material. For example, a color wheel can include blue, green, and red phosphors combined with an ultraviolet (UV) light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a UV light source. The color wheel contains three phosphor-containing regions. The three phosphor-containing regions are for conversion of UV light to blue light, conversion of UV light to green light, and conversion of UV light to red light, respectively. In operation, the color wheel sequentially emits blue, green, and red light from the phosphor-containing regions. Blue, green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, blue, green and red light are collected by optics and redirected to the microdisplay. The UV light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. It is understood that other combinations of colored light sources and their color wheel are possible.</p><p>According to yet another embodiment, the invention provides a projection device. The device includes a housing having an opening. The device includes an input interface for receiving one or more image frames. The device includes a laser source. Laser sources include blue laser diodes, green laser diodes and red laser diodes. Blue laser diodes are fabricated on non-polar or semi-polar oriented Ga-containing substrates, and the peak operating wavelength of blue laser diodes is about 430-480 nm. Green laser diodes are fabricated on nonpolar or semipolar oriented Ga-containing substrates, and the peak operating wavelength of green laser diodes is about 490 nm to 540 nm. Red lasers can be made from AlInGaP. A green laser diode has a wavelength of about 490 nm to 540 nm. The laser source is configured to generate a laser beam by combining outputs from the blue, green and red laser diodes. The device includes a digital light processing chip. The digital light processing chip contains three digital mirror devices. Each digital mirror device includes multiple mirrors. Each mirror corresponds to one or more pixels of one or more image frames. The color beams are each projected onto a digital mirror device. The apparatus includes a power supply electrically connected to a laser source and a digital light processing chip. Many variations of this embodiment are possible, for example, in one embodiment the green and blue laser diodes share the same substrate, or two or more of the different colored lasers can be housed in the same package. In this same-package embodiment, the outputs from the blue, green and red laser diodes are combined into a single beam.</p><p>As an example, the color wheel may include phosphor materials that change the color of light emitted from the light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source and a red light source. The color wheel includes grooves for blue light and phosphors that include regions for converting blue light to green light. In operation, a blue light source (eg, a blue laser diode or a blue LED) provides blue light through the grooves to excite green light from the phosphor-containing regions. A red light source separately provides red light. Green light from the phosphor can be transmitted through the color wheel or reflected from the color wheel. In either case, green light is collected by optics and redirected to the microdisplay. Blue light passing through the groove is also directed to the microdisplay. The blue light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. Alternatively, a green laser diode may be used instead of a blue laser diode using phosphor to emit green light. It is understood that other combinations of colored light sources and their color wheel are possible.</p><p>As another example, the color wheel may include multiple phosphor materials. For example, a color wheel can include both green and red phosphors combined with a blue light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source. The color wheel includes a groove for blue laser light and two phosphor-containing regions for conversion of blue light to green light and blue light to red light, respectively. In operation, a blue light source (eg, a blue laser diode or blue LED) provides blue light through the grooves and excites green and red light from the phosphor-containing regions. Green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, green and red light are collected by optics and redirected to the microdisplay. The blue light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. It is understood that other combinations of colored light sources and their color wheel are possible.</p><p>As another example, a color wheel may include blue phosphor material, green phosphor material, and red phosphor material. For example, a color wheel may include a combination of blue, green and red phosphors and an ultraviolet (UV) light source. In certain embodiments, the color wheel includes multiple regions, each of the multiple regions corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a UV light source. The color wheel contains three phosphor-containing regions. The three phosphor-containing regions are for conversion of UV light to blue light, conversion of UV light to green light, and conversion of UV light to red light, respectively. In operation, the color wheel sequentially emits blue, green, and red light from the phosphor-containing regions. Blue, green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, blue, green and red light are collected by optics and redirected to the microdisplay. The UV light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. It is understood that other combinations of colored light sources and their color wheel are possible.</p>

<p>Using the present invention achieves a variety of objectives compared to existing technology. Specifically, the present invention enables a cost-effective projection system with efficient light sources. In certain embodiments, the light source can be manufactured in a relatively simple and cost effective manner. Depending on the embodiment, the device and method can be manufactured by those skilled in the art using conventional materials and/or methods. In one or more embodiments, the laser device is capable of multiple wavelengths. Of course, other modifications, changes and alternatives are possible. Depending on the embodiment, one or more of these objectives can be achieved. These and other advantages are explained in detail in the specification and drawings.</p><p>The present invention achieves these and other benefits in the context of known processing technology. However, a further understanding of the nature and advantages of the present invention may be realized by reference to the latter portions of the specification and accompanying drawings.</p>

<figref num="1">FIG. 1 is a diagram showing a conventional projection system.</figref>

<figref num="2">FIG. 2 shows a projection device according to an embodiment of the invention.</figref>

<figref num="2-A">FIG. 2-A is a detailed cross-sectional view of a laser device 200 fabricated on a {20-21} substrate, according to an embodiment of the present invention.</figref>

<figref num="2-B">FIG. 2-B is a diagram showing a projector with an LED light source.</figref>

<figref num="3">FIG. 3 is another view of a projection device according to an embodiment of the invention;</figref>

<figref num="3-A">FIG. 3-A is a diagram showing co-packaged laser diodes according to an embodiment of the present invention.</figref>

<figref num="3-B">FIG. 3-B is a cross-sectional view of an active region for graded emission wavelengths, according to an embodiment of the present invention.</figref>

<figref num="3-C">FIG. 3-C is a cross-sectional view of multiple active regions, according to an embodiment of the present invention.</figref>

<figref num="3-D">FIG. 3-D is a diagram showing a projector with an LED light source.</figref>

<figref num="4">FIG. 4 shows a projection device according to an embodiment of the invention.</figref>

<figref num="4-A">FIG. 4-A is a diagram illustrating laser diodes integrated into a single package form, according to an embodiment of the present invention.</figref>

<figref num="5">FIG. 5 is a diagram of a DLP projection device according to an embodiment of the invention.</figref>

<figref num="5-A">FIG. 5-A is a diagram illustrating a DLP projector according to an embodiment of the invention.</figref>

<figref num="6">FIG. 6 is a diagram illustrating a 3-chip DLP projection system according to an embodiment of the invention.</figref>

<figref num="7">FIG. 7 is an illustration of a 3D display with polarized images filtered by polarized glasses.</figref>

<figref num="8">FIG. 8 is a diagram illustrating a 3D projection system according to an embodiment of the invention.</figref>

<figref num="9">FIG. 9 is a diagram illustrating an LCOS projection system 900 according to an embodiment of the invention.</figref>

The present invention relates to display technology. More specifically, in projection display systems provided by various embodiments of the present invention, one or more laser diodes are used as light sources to present images. In one set of embodiments, projector systems provided by the present invention employ blue and/or green lasers fabricated using gallium nitride-containing materials. In another set of embodiments, the invention provides a projection system having a digital lighting processing engine. The digital lighting processing engine is illuminated by a blue laser device and/or a green laser device. Other embodiments also exist.

As explained above, conventional display types are often inadequate. Small projectors solve this problem by projecting large images (up to and beyond 60 inches) from handheld devices, allowing movies, internet surfing and more in size formats that display consumers are accustomed to. and other images can be shared. As a result, pocket projectors, standalone companion pico-projectors and embedded pico-projectors in mobile devices (eg, phones) are becoming increasingly available.

Today, commercial InGaN-based lasers and LEDs are grown on the polar c-plane of GaN crystals. It is well known that when InGaN light emitting layers are deposited on top of this conventional GaN layer, problems arise due to electric fields associated with internal polarization. In these structures, spontaneous polarization is due to charge asymmetry during GaN bonding and piezoelectric polarization is due to strain. In quantum well structures, these polarization fields cause the electron and hole wavefunctions to be spaced apart, thereby reducing their radiative recombination efficiency. Because piezoelectric polarization is strain dependent, these internal fields become stronger and the indium content in the exit layer required for blue lasers and LEDs (especially green lasers and LEDs) also increases.

Quantum confined Stark effect (QCSE) in the light-extraction quantum well layer occurs due to the internal electric field, in addition to the reduction of the radiative recombination coefficient, which reduces the LED brightness. Due to this effect, a blue shift of the peak emission wavelength occurs and the carrier density in the quantum well layer increases. Since carrier density increases with increasing current, a shift in peak wavelength occurs as a function of current in blue or green LEDs. Such a dependence of wavelength on drive current is not ideal for display applications where current modulation schemes are implemented for LEDs. This is because the color change occurs with current. In a laser diode, carrier density increases with increasing current until the laser threshold begins. As the laser threshold rotates, the gain exceeds the losses in the cavity. In order to achieve lasing wavelengths in the blue and green regions, when the blue shift in such peak wavelength falls below a threshold, the light output layer is forced to grow, resulting in an increased indium content, Blue shift is compensated. It is well known that such increased indium content can lead to deterioration of material quality due to increased strain and indium-segregation. For the realization of highly efficient blue and green lasers and LEDs, it is desirable to reduce or eliminate polarization-related electric fields.

Growth of device structures on new GaN orientations (e.g., non-polar a-plane or m-plane or semi-polar planes between non-polar and polar c-planes) has long been understood to eliminate or mitigate the polarization field. can be done. On these novel crystal planes, unique design freedom is obtained on both epitaxial and device structures. Furthermore, anisotropic strain in InGaN films grown on nonpolar and semipolar substrates reduces the effective hole mass, resulting in an increase in differential gain and a higher transparent current density in laser diodes. can decline. Devices (e.g., blue and green lasers and LEDs fabricated on nonpolar and semipolar planes) provide excitation potentials to improve performance, increase radiative recombination efficiency, and reduce drive current. The peak wavelength blue shift is reduced, device design flexibility is increased, and favorable epitaxial growth quality is obtained.

Examples of typical projectors based on solid state emitters are given below. light source (laser or LED), optics, microdisplay (eg, liquid crystal on silicon (LCOS) or digital micromirror device (DMD)), driver board, and power supply (ie, battery or power adapter).

Depending on the application, projection systems can utilize polarized or polarized light. For example, single-scanner projection systems (eg, picoprojectors) and DLP-based systems typically use unpolarized light sources. In certain applications (eg projection systems using LCOS) polarized light sources are desirable. Typically, the blue and green LEDs (and even red LEDs) used in conventional projectors are unpolarized (or exhibit a low polarization ratio), which reduces optical losses from polarization-dependent optical components. It becomes excessive and degrades spatial mode quality, resulting in the need for large LCOS or LCD chips, precluding their use in compact designs. This is because the light cannot be focused into a small area. Due to the splitting of the X- and Y-electron valence bands on nonpolar and semipolar GaN, the emission from devices (e.g., LEDs fabricated on these platforms) is essentially Polarization. The use of semi-polar and/or non-polar GaN-based LEDs in projection displays using LCOS technology or other light valves that require polarization reduces components (e.g., causes increased system complexity and cost). Optical losses associated with LEDs are minimized without the need for additional polarized recyclers. In conventional projection systems, lasers and/or LEDs are often used as light sources for image illumination. Typically, laser light sources outperform LED light sources in projection systems.

FIG. 1 is a diagram showing a conventional projection system. As shown, blue laser light, green laser light and red laser light are combined to obtain one laser beam, which is then projected onto the MEMS scanning mirror.

In a conventional projection system (eg, such as that shown in FIG. 1), a green second harmonic generation (SHG) laser is used to provide green laser light. Currently, there is no direct diode application for green laser emission, forcing the use of frequency doubled 1060 nm diode lasers. This 1060 nm diode laser is expensive, bulky, difficult to modulate at high speed, and emits a narrow spectrum that causes speckle in the image. In addition, these devices require second harmonic generation using periodically pulsed lithium niobate (PPLN), resulting in significant efficiency losses associated with the technology.

First is the efficiency of the 1060nm device itself. Second, there are optical coupling losses associated with guiding light into and out of the PPLN. Third, conversion loss occurs within the PPLN. Finally, there are losses associated with cooling the components to the correct temperature.

In order to produce highly efficient displays that maximize battery life and minimize cost, size and weight, it is necessary to minimize optical losses from the system. Non-limiting sources of optical loss in systems include losses from optical elements whose transmission is polarization dependent. Many compact projectors (eg pico projectors) use microdisplay technologies (eg LCOS or LCD) that are highly polarization sensitive. Common LCOS-based displays typically often require highly polarized light sources due to the nature of liquid crystal display technology.

In various embodiments, the present invention provides blue direct diode GaN lasers and green direct diode GaN lasers. Blue direct diode GaN lasers and green direct diode GaN lasers make them ideal for a wide variety of projection and display types (e.g. pico projectors, DLP projectors, liquid crystal displays (e.g. liquid crystal on silicon or "LCOS"), etc.) It provides highly polarized output, single spatial mode, medium to large spectral width, high efficiency, and high modulation speed.

By using highly polarized light sources in projection displays such as those provided by embodiments of the present invention, optical efficiency can be maximized, resulting in minimum cost and maximum flexibility in the selection of optical components. It should be understood that it is possible. For conventional illumination sources (eg, non-polarized LEDs and their systems) complex optics are required for polarization recycling due to increased efficiency from non-polar light sources. In contrast, forming blue lasers and/or LEDs and green lasers and/or LEDs on non-polar or semi-polar GaN results in a highly polarized light output, which provides additional work to handle polarization. No optical elements are required.

As described in this invention, direct diode lasers with GaN lasers are used for the blue and green sources. Conventional c-plane GaN lasers emit unpolarized or nearly unpolarized light when the laser is below threshold. When the laser reaches threshold, the output light becomes polarized and the current increases. In contrast, lasers fabricated on non-polar or semi-polar GaN, according to embodiments of the present invention, emit polarizations below threshold, have higher polarization ratios, and have higher currents. By using highly polarized light sources in projection displays, optical efficiency can be maximized at minimum cost and maximum flexibility in the selection of optical components can be obtained.

Optical losses from the system need to be minimized in order to produce highly efficient displays that allow maximizing battery life and minimizing cost, size and weight. In LCOS systems, the transform LCOS is often made as small as possible to accommodate small volumes and to reduce cost. Therefore, high optical spatial brightness laser sources are needed to achieve maximum optical efficiency and minimum power consumption, size and weight within the display.

For conventional LEDs, the poor spatial mode quality requires large LCOS or LCD chips and is not available in compact designs. This is because the light cannot be focused into a small area. In contrast, the blue and green direct diode GaN lasers according to the present invention exhibit a single spatial mode for maximum throughput.

Embodiments of the present invention also provide the benefit of reduced speckling. For example, the frequency doubled 1060 nm diode laser used in conventional systems produces a narrow spectrum that causes speckle in the image. For direct-diode visible lasers (e.g., green lasers) used in embodiments of the present invention, the spectrum can be increased &gt;100x, thus substantially reducing speckle in the image, making it expensive and bulky. reduce the need for additional components.

Furthermore, for the frequency doubled 1060 nm diode lasers used in conventional systems, there is second harmonic generation, which is inefficient. With the direct diode visible laser used in the present invention, the efficiency can be substantially higher and also benefit from reduced optical components and size and weight of the system.

As explained above, a typical miniature projector (eg, pico projector) includes the following components. light source (laser or LED), optics, microdisplay (eg LCOS display or DMD display), driver board, power supply (ie battery or power adapter).

Currently, blue LEDs and green LEDs (even red LEDs) are unpolarized, resulting in excessive optical loss and poor spatial mode quality, resulting in the need for large LCOS or LCD chips, Use in compact designs becomes impossible. This is because the light cannot be focused into a small area. Due to the splitting of the X- and Y-electron valence bands on nonpolar and semipolar GaN, the emission from devices (e.g., LEDs fabricated on these platforms) is essentially Polarization. By using semi-polar and/or non-polar GaN-based LEDs in projection displays or other LCOS technologies, there is no need for additional components (e.g., polarization recyclers that increase system complexity and cost), Optical losses associated with unpolarized LEDs are minimized.

Currently, there is no direct diode application for green laser emission, forcing the use of frequency doubled 1060 nm diode lasers. This double frequency 1060 nm diode laser is expensive, bulky, difficult to modulate at high speed, and emits a narrow spectrum that causes speckle in the image. In addition, these devices require second harmonic generation using periodically pulsed lithium niobate (PPLN), resulting in significant efficiency losses associated with the technology. First is the efficiency of the 1060nm device itself. Second, there are optical coupling losses associated with guiding light into and out of the PPLN. Third, conversion loss occurs within the PPLN. Finally, there are losses associated with cooling the components to the correct temperature.

Blue direct-diode GaN lasers and green direct-diode GaN lasers according to embodiments of the present invention provide high polarized output, single spatial mode, medium to large spectral width, high efficiency and high modulation speed, ideal for liquid crystal displays. can get.

The conventional approach to frequency doubling achieves high spatial brightness, but high modulation frequencies are not readily available and image artifacts occur in trials. This limits the source modulation frequency to 100 MHz and requires the use of amplitude (analog) modulation. As frequency capability rises to 300 MHz, pulsed (digital) modulation can be used, allowing for system simplification and the need for look-up tables.

Modulation frequencies in excess of 300 MHz can be achieved with a direct diode solution according to embodiments of the present invention, making digital operation feasible. Non-polar and/or semi-polar GaN lasers greatly enhance the potential for direct diode green solutions, which in turn greatly enhance the potential for digital scanning micromirror projectors.

FIG. 2 is a simplified diagram showing a projection device according to an embodiment of the invention. FIG. 2 is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize many modifications, substitutions and alterations. Projection system 250 includes MEMS scanning mirror 251 , mirror 252 , optical member 254 , green laser diode 253 , red laser diode 256 and blue laser diode 255 .

As an example, projection system 250 is a pico-projector. In addition to the components shown in FIG. 2, projection system 250 also includes a housing having an opening and an input interface for receiving one or more image frames. Projection system 250 also includes a video processing module. In one embodiment, the video processing module is electrically connected to the ASIC to drive the laser diode and MEMS scanning mirror scanning mirror 251 .

In one embodiment, a laser diode along with optical member 254 forms a laser source. Green laser diode 253 is characterized by a wavelength of approximately 490 nm to 540 nm. The laser source is configured to generate a laser beam by combining outputs from the blue, green and red laser diodes. Depending on the application, various types of optical components can be used to combine the light output from the laser diodes. For example, optical components can be dichroic lenses, prisms, converging lenses, and the like. In certain embodiments, the combined laser beam is polarized

In one embodiment, a laser driver module is provided. In particular, the laser driver module is adapted to adjust the amount of power provided to the laser diode. For example, the laser driver module generates one or more pixels from one or more image frames based on three drive currents, each adapted to drive a laser diode. In certain embodiments, the laser driver module is configured to generate pulse modulated signals in the frequency range of approximately 50-300 MHz.

MEMS scanning mirror 251 is configured to project a laser beam through an aperture to a specific location. For example, MEMS scanning mirror 251 processes one pixel on a particular location corresponding to a pixel of the image at a particular timing. At high frequencies, the pixels projected from MEMS scanning mirror 251 form an image.

MEMS scanning mirror 251 receives light from a laser source through mirror 252 . As shown, a mirror 252 is provided proximate the laser source. In particular, the optics are adapted to direct the laser beam onto the MEMS scanning mirror 251 .

It should be appreciated that projection system 250 includes other components (eg, a laser source and a power supply electrically connected to MEMS scanning mirror 251). Other components include buffer memory, communication interfaces, network interfaces, etc.

As mentioned above, the primary component of projection system 250 is the laser light source. In contrast to conventional projection systems, highly efficient laser diodes are used in embodiments of the present invention. In certain embodiments, the blue laser diode operates in a single transverse mode. For example, blue laser diodes are characterized in that their spectral width is about 0.5 nm to 2 nm. In certain embodiments, blue laser diodes are designed for portable applications (e.g., embedded and companion picoprojectors) and feature single mode output from 60mW to 445nm in a compact TO-38 package. . For example, blue lasers operate with high efficiency and consume minimal power over a wide temperature range, making them ideal for consumer projection display applications, defense pointer and illuminator applications, biomedical instrumentation and therapy. applications, as well as the rigorous demands of industrial imaging applications. According to various embodiments, blue lasers are fabricated on GaN substrates based on Indium Gallium Nitride (InGaN) semiconductor technology.

In various embodiments, blue and green laser diodes are fabricated using GaN materials. Blue laser diodes can be semi-polar or non-polar. Similarly, green laser diodes can be semi-polar or non-polar. For example, red laser diodes can be made using GaAlInP material. For example, the following laser diode combinations are possible, but other combinations are also possible. Specifically, blue polar + green nonpolar + red *AlInGaP, blue polar + green semipolar + red *AlInGaP, blue polar + green polar + red *AlInGaP, blue semipolar + green nonpolar + red *AlInGaP, blue semi-polar + green semi-polar + red *AlInGaP, blue semi-polar + green polar + red *AlInGaP, blue non-polar + green non-polar + red *AlInGaP, blue non-polar + green semi-polar + red *AlInGaP, blue non-polar + There is green polarity + red * AlInGaP.

As an example, blue and green laser diodes can be fabricated on the m-plane. In certain embodiments, a blue or green laser diode includes a gallium nitride substrate member having an off-cut m-plane crystalline surface region. In certain embodiments, this offcut angle is -2.0 to -0.5 degrees with respect to the c-plane. In certain embodiments, the gallium nitride substrate member is a bulk GaN substrate characterized by a semi-polar or non-polar crystalline surface region, but may be others. In certain embodiments, the bulk nitrided GaN substrate comprises nitrogen and has a surface dislocation density of 10⁵cm^-2lower than Nitride crystals or wafers are Al_xIn_yGa_1-xyN, where 0x, y, x+y1. In one particular embodiment, the nitride crystal comprises GaN, but may be others. In one or more embodiments, the GaN substrate is oriented substantially perpendicular or oblique to the surface by about 10⁵cm^-2~ about 10⁸cm^-2has threading dislocations at a concentration of Due to perpendicular or oblique dislocations, the surface dislocation density is about 10⁵cm^-2below. In certain embodiments, devices can be fabricated on semipolar substrates that are slightly offcut.

In a particular embodiment, the laser is fabricated on a {20-21} semipolar GaN surface texture and the device has a laser stripe region. A laser stripe region is formed overlying a portion of the offcut crystallographic orientation surface region. In certain embodiments, the laser stripe region is characterized by a cavity orientation in which the projection direction is substantially the c-direction. The c-direction is substantially perpendicular to the a-direction. In certain embodiments, the laser strip region has a first end and a second end. In a preferred embodiment, the laser cavity is oriented on a gallium and nitrogen containing substrate with a {20-21} pair of cleaved mirror structures in c-direction projection at the cavity ends. Of course, other modifications, alterations and alternatives are possible.

In a particular embodiment, the laser is fabricated on a nonpolar m-plane GaN surface texture, and the device has a laser stripe region formed overlying a portion of the offcut crystallographic alignment surface region. In certain embodiments, the laser stripe region is characterized by the cavity orientation being substantially in the c-direction. The c-direction is substantially perpendicular to the a-direction. In certain embodiments, the laser strip region has a first end and a second end. In a preferred embodiment, the laser cavity is oriented in the c-direction on an m-plane gallium and nitrogen containing substrate with a pair of cleaved mirror structures at the cavity ends. Of course, other modifications, alterations and alternatives are possible.

In a preferred embodiment, the device comprises a first cleaved facet on the first end of the laser stripe region and a second cleaved facet on the second end of the laser stripe region. have In one or more embodiments, the first cleavage is substantially parallel to the second cleavage plane. A mirror surface is formed on each cleaved surface. The first cleaved plane includes a first mirror surface. In a preferred embodiment, an upper skip scribing scribing and breaking process provides the first mirror surface. Any suitable technique (eg, diamond scribing or laser scribing or a combination) can be used in the scribing process. In certain embodiments, the first mirror surface includes a reflective coating. Reflective coatings are selected from silicon dioxide, hafnium and titania, tantalum pentoxide, zirconia, combinations thereof, and the like. Depending on the embodiment, the first mirror surface may include an antireflection coating. Of course, other modifications, alterations and alternatives are possible.

Also, in a preferred embodiment, the second cleaved surface comprises a second mirror surface. A second mirror surface is provided by an upper skip scribing scribing and breaking process according to certain embodiments. Preferably, the scribing is diamond scribing, laser scribing, or the like. In certain embodiments, the second mirror surface includes a reflective coating (eg, silicon dioxide, hafnium and titania, tantalum pentoxide, zirconia, combinations, etc.). In certain embodiments, the second mirror surface includes an antireflective coating. Of course, other modifications, alterations and alternatives are possible.

In certain embodiments, a laser stripe has a length and a width. The length ranges from about 50 microns to about 3000 microns. The width of the strip ranges from about 0.5 microns to about 50 microns, although other dimensions are possible. In certain embodiments, the widths are substantially the same size, although slight variations are possible. Widths and lengths are often formed using masking and etching processes that are also commonly used in the art.

In certain embodiments, the present invention provides another device structure capable of emitting light above 501 nm in ridge laser embodiments. Devices are provided with one or more of the following non-limiting epitaxial growth elements. Specifically, an n-GaN cladding layer (thickness 100 nm to 5000 nm, Si doping level 5E17 to 3E18 cm), an n-side SCH layer (which contains InGaN with a molar ratio of 3% to 10% indium). , a thickness of 20-100 nm), a plurality of quantum well active region layers (which include at least two 2.0-8.5 nm InGaN quantum wells, and at least two 2.0-8.5 nm InGaN quantum wells are A thin 2.5 nm or greater and optionally separated by a GaN barrier through a thickness of up to about 8 nm), a p-side SCH layer (which consists of InGaN with a molar ratio of 1% to 10% indium). a thickness of 15 nm to 100 nm), an electron blocking layer (which comprises AlGaN with a molar ratio of aluminum of 12% to 22%, a thickness of 5 nm to 20 nm, and is doped with Mg); p-GaN cladding layer (which has a thickness of 400 nm to 1000 nm and a Mg doping level of 2E17 cm-3 to 2E19 cm-3), p++-GaN contact layer (which has a thickness of 20 nm to 40 nm). and the Mg doping level is 1E19cm-3~1E21cm-3).

In certain embodiments, laser devices are fabricated on {20-21} semipolar Ga-containing substrates. However, it should be understood that laser devices can also be fabricated on other types of substrates (eg, non-polarized oriented Ga-containing substrates).

Light sources based on red, green and blue sources are widely used, but other combinations are possible. According to embodiments of the present invention, the light sources used in the projection system combine a yellow light source with red, green and blue sources. For example, the addition of a yellow light source results in RBG projection and display systems with improved color characteristics (eg, wider chromaticity). In certain embodiments, an RGYB light source is used for the projection system. The yellow light source can be a yellow laser diode made from gallium nitride material or AlInGaP material. In various embodiments, the yellow light source can have a polar, non-polar or semi-polar orientation. It should be understood that the projection system according to the invention can also use light sources of other colors. For example, other colors include cyan and magenta. In certain embodiments, different colored laser diodes are packaged separately. In another specific embodiment, two or more different colored laser diodes are packaged together. In yet another specific embodiment, two or more different colored laser diodes are fabricated on the same substrate.

FIG. 2-A is a detailed cross-sectional view of a laser device 200 fabricated on a {20-21} substrate, according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims herein. Those skilled in the art will recognize other modifications, alterations and alternatives. As shown, the laser device includes a gallium nitride substrate 203 . An n-type metal back contact region 201 is provided on the underside of the gallium nitride substrate 203 . In certain embodiments, this metal back contact region is formed of a suitable material (eg, those described below). Further details of the contact area are provided herein and in greater detail below.

In certain embodiments, the device also has a superimposed n-type gallium nitride layer 205 , an active region 207 , and a superimposed p-type gallium nitride layer structure structured as a laser stripe region 209 . In certain embodiments, each of these regions is formed using at least metal-organic chemical vapor deposition (MOCVD) epitaxial deposition techniques, molecular beam epitaxy (MBE), or other epitaxial growth techniques suitable for GaN growth. be. In certain embodiments, the epitaxial layer is a high quality epitaxial layer of GaN grown n-type gallium nitride layer. In some embodiments, the high quality layer is, for example, Si or O with about 10¹⁶cm^-3~10²⁰cm^-3to form an n-type material.

In certain embodiments, n-type Al_uIn_vGa_1-uvAn N layer (where 0u, v, u+v1) is deposited on the substrate. In certain embodiments, the carrier concentration is about 10¹⁶cm^-3~10²⁰cm^-3can be in the range of Deposition can be done using MOCVD or MBE. Of course, other modifications, alterations and alternatives are possible.

As an example, a bulk GaN substrate is placed on a susceptor within an MOCVD reactor. After closing, evacuating and backfilling the reactor (or using a load lock configuration) to atmospheric pressure, the susceptor is heated to a temperature of about 900 to about 1200 degrees Celsius in the presence of a nitrogen-containing gas. In one particular embodiment, the susceptor is heated to approximately 1100 degrees Celsius under flowing ammonia. A flow of a gallium-containing metal-organic precursor (eg, trimethylgallium (TMG) or triethylgallium (TEG)) is initiated in the carrier gas at a rate of approximately 1-50 cubic centimeters per minute (sccm). Carrier gases may include hydrogen, helium, nitrogen or argon. At this time, the flow ratio of the group V precursor (ammonia) to the group III precursor (trimethylgallium, triethylgallium, trimethylindium, trimethylaluminum) is about 2,000 to about 12,000. Start the flow of disilane in the carrier gas at a total flow rate of about 0.1-10 sccm.

In certain embodiments, the laser stripe region is composed of p-type gallium nitride layer 209 . In certain embodiments, an etching process selected from dry etching or wet etching provides the laser stripes. In preferred embodiments, the etching process may be dry or otherwise. As an example, the dry etch process is an inductively coupled process using a reactive ion etch process using chlorine-bearing species or similar chemistries. Also by way of example, chlorine-bearing species are often derived from chlorine gas and the like. The device also has an overlapping dielectric area that exposes the 213 contact area. In certain embodiments, the dielectric region is an oxide (eg, silicon dioxide or silicon nitride), but can be others. The contact area is connected to overlying metal layer 215 . The superimposed metal layer is a multilayer structure including palladium and gold (Pd/Au), platinum and gold (Pt/Au), nickel gold (Ni/Au), but may be others. Of course, other modifications, alterations and alternatives are possible.

In certain embodiments, the laser device has an active region 207 . The active region, according to one or more embodiments, can include 1-20 quantum well regions. As an example, n-type Al_uIn_vGa_1-uvAfter depositing the N layer to a predetermined thickness for a predetermined period, the active layer is deposited. The active layer may include multiple quantum wells, including 2-10 quantum wells. Quantum wells may include InGaN sandwiched by GaN barrier layers. In other embodiments, the well and barrier layers are Al_wIn_xGa_1-wxN and Al_yIn_zGa_1-yzN (where 0w, x, y, z, w+x, y+z1, w&lt;u, y and/or x&gt;v, z), whereby the well layer (singular or multiple) will be smaller than the bandgap of the barrier layer(s) and n-type layer(s). The thickness of the well layer and barrier layer can each be from about 1 nm to about 20 nm. The composition and structure of the active layer are chosen to provide emission at a preselected wavelength. The active layer may be left undoped (or may be unintentionally doped), or may be n-type doped or p-type doped. Of course, other modifications, alterations and alternatives are possible.

In certain embodiments, the active region can also include an electron blocking region and separate confinement heterostructures. In some embodiments it is preferred to deposit an electron blocking layer. The electron blocking layer is Al_sIn_tGa_1-stN, where 0s, t, s+t1, has a higher bandgap than the active layer, and can be p-type doped. In one particular embodiment, the electron blocking layer comprises AlGaN. In another embodiment, the electron blocking layer comprises an AlGaN/GaN superlattice structure, comprising alternating AlGaN and GaN layers, the AlGaN and GaN layers each having a thickness of about 0.2 nm to about 5 nm. Of course, other modifications, alterations and alternatives are possible.

As noted above, a p-type gallium nitride structure is deposited over the electron blocking layer and the active layer(s). The p-type layer is about 10¹⁶cm^-3~10²²cm^-3and the thickness of the p-type layer can be from about 5 nm to about 1000 nm. Electrical contact can be improved by doping the outermost 1-50 nm of the p-type layer more highly than the rest of the layer. In certain embodiments, an etching process selected from dry etching or wet etching provides the laser stripes. In preferred embodiments, the etching process may be dry or otherwise. The device also has an overlapping dielectric area that exposes the 213 contact area. In certain embodiments, the dielectric region comprises an oxide (eg, silicon dioxide), but may be others (eg, silicon nitride). Of course, other modifications, alterations and alternatives are possible.

It should be appreciated that the light source of projector 250 may also include one or more LEDs. FIG. 2-B is a simplified diagram showing a projector with an LED light source. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As an example, blue and green LEDs are manufactured from gallium nitride-containing materials. In one particular embodiment, the blue LED is characterized by a non-polar orientation. In another embodiment, the blue LED is characterized by a semi-polar orientation.

FIG. 3 is another view of a projection device according to an embodiment of the invention; This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. In FIG. 3, the projection device includes a MEMS scanning mirror, a mirror, a light converting member, a red laser diode, a blue diode and a green laser diode. A blue laser diode and a green laser diode as shown are integrated in a single package. For example, blue and green lasers share the same substrate and surface. The output from the blue and green laser diodes are emitted from a common surface. It will be appreciated that co-packaging the blue and green laser diodes can substantially reduce the size and cost (eg, reduce part count) of the projector device.

In addition, green and blue laser diodes are characterized by high efficiency. For example, blue on green laser diodes are fabricated from bulk gallium nitride material. Blue laser diodes can be non-polar or semi-polar oriented. Green laser diodes can similarly be non-polar or semi-polar oriented. For example, the following laser diode combinations are possible, but other possibilities are also possible. Specifically, blue polar + green nonpolar + red *AlInGaP, blue polar + green semipolar + red *AlInGaP, blue polar + green polar + red *AlInGaP, blue semipolar + green nonpolar + red *AlInGaP, blue semi-polar + green semi-polar + red *AlInGaP, blue semi-polar + green polar + red *AlInGaP, blue non-polar + green non-polar + red *AlInGaP, blue non-polar + green semi-polar + red *AlInGaP, blue non-polar + green polarity + red * AlInGaP.

In one embodiment, green laser diodes are characterized by wavelengths between 480 nm and 540 nm. This wavelength range differs from conventional manufactured devices that use infrared laser diodes (ie, those with an emission wavelength of about 1060 nm) and that use SHG to double the frequency.

FIG. 3-A is a simplified diagram of co-packaged laser diodes according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in Figure 3-A, two laser diodes are provided on a single package. For example, laser 1 is shown in a blue laser diode and laser 2 is a green laser diode. Optical elements can be used to combine the laser outputs.

The output of two lasers, such as that shown in Figure 3-A, can be combined in many ways. For example, optical components (eg, dichroic lenses, waveguides) can be used to combine the outputs of Laser 1 and Laser 2 as shown.

In another embodiment, a blue laser diode and a green laser diode are monolithically integrated. FIG. 3-B is a cross-sectional view of a graded emission wavelength active region according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. For example, as shown in FIG. 3-B, active regions are provided having different emission gradients. Ridge waveguides in different portions of the active region are adapted to emit different wavelengths.

FIG. 3-C is a simplified diagram illustrating cross-sections of multiple active regions according to embodiments of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. Specifically, each active region is associated with a particular wavelength.

It should be appreciated that the light source of projector 300 may also include one or more LEDs. FIG. 3-D is a simplified diagram showing a projector with an LED light source. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As an example, blue and green LEDs are manufactured from gallium nitride-containing materials. In one particular embodiment, the blue LED is characterized by a non-polar orientation. In another embodiment, the blue LED is characterized by a semi-polar orientation.

FIG. 4 is a simplified diagram of a projection device according to an embodiment of the invention; This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in FIG. 4, a light source 401 is obtained by integrating a blue laser diode, a green laser diode and a red laser diode. Light source 401 combines the outputs of each of the laser diodes. The combined light is projected onto a mirror, which reflects the combined light onto a MEMS scanning mirror. By providing the laser diodes in the same package, both the size and cost of the light source 401 can be reduced. For example, the following laser diode combinations are possible, but it should be understood that other combinations are also possible. For example, blue polarity + green non-polar + red *AlInGaP, blue polarity + green semi-polar + red *AlInGaP, blue polarity + green polarity + red *AlInGaP, blue semi-polar + green non-polar + red *AlInGaP, blue semi-polar + green semi-polar + red *AlInGaP, blue semi-polar + green polar + red *AlInGaP, blue non-polar + green non-polar + red *AlInGaP, blue non-polar + green semi-polar + red *AlInGaP, blue non-polar + green polar + Red *AlInGaP.

FIG. 4-A is a simplified diagram showing laser diodes integrated into a single package form, according to an embodiment of the present invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. For example, laser 1 can be a green laser diode, laser 2 can be a red laser diode, and laser 3 can be a blue laser diode. Depending on the application, green laser diodes can be fabricated on semi-polar gallium-containing substrates, non-polar gallium-containing substrates or polar gallium-containing substrates. Similarly, blue laser diodes can be formed on semipolar gallium-containing substrates, non-polar gallium-containing substrates, or polar gallium-containing substrates.

It should be appreciated that a wide variety of projection systems according to the invention have a wide variety of applications. In various embodiments, the projection systems described above are integrated onto mobile phones, cameras, personal computers, portable computers and other electronic devices.

FIG. 5 is a simplified diagram of a DLP projection device according to an embodiment of the invention. This diagram is exemplary only and should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in FIG. 5, the projection device particularly includes a light source, a condenser lens, a color wheel, a molded lens, a digital lighting processor (DLP) board, and a projection lens. DLP substrates include processors, memory, and digital micromirror devices (DMDs), among others.

As an example, the color wheel may include phosphor materials that change the color of light emitted from the light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source and a red light source. The color wheel includes grooves for blue light and phosphors that include regions for converting blue light to green light. In operation, a blue light source (eg, a blue laser diode or blue LED) provides blue light through the grooves and excites green light from the phosphor-containing regions, and a red light source separately provides red light. Green light from the phosphor may pass through the color wheel or may be reflected from the color wheel. In either case, green light is collected by optics and redirected to the microdisplay. Blue light passing through the groove is also directed to the microdisplay. The blue light source can be a laser diode and/or an LED made on non-polar or semi-polar oriented GaN. In some cases, combining both blue lasers and blue LEDs allows for improved color characteristics. Another source of green light is green laser diodes and/or green LEDs, which can be made from non-polar Ga-containing substrates or semi-polar Ga-containing substrates. In some embodiments it may be advantageous to use some combination of LED, laser and/or phosphor converted green light. It is understood that other combinations of colored light sources and their color wheel are possible.

As another example, the color wheel may include multiple phosphor materials. For example, a color wheel can include both green and red phosphors combined with a blue light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a blue light source. The color wheel includes a groove for blue laser light and two phosphor-containing regions for conversion of blue light to green light and blue light to red light, respectively. In operation, a blue light source (eg, a blue laser diode or blue LED) provides blue light through the grooves and excites green and red light from the phosphor-containing regions. Green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, green and red light is collected by optics and redirected to the microdisplay. The blue light source may be a laser diode or an LED made on non-polar or semi-polar oriented GaN.

As another example, a color wheel may include blue phosphor material, green phosphor material, and red phosphor material. For example, a color wheel may include a combination of blue, green and red phosphors and an ultraviolet (UV) light source. In certain embodiments, the color wheel includes multiple regions, each region corresponding to a particular color (eg, red, green, blue, etc.). In an exemplary embodiment, the projector includes a light source that includes a UV light source. The color wheel includes three phosphor-containing regions for conversion of UV light to blue light, conversion of UV light to green light, and conversion of UV light to red light, respectively. In operation, the color wheel sequentially emits blue, green, and red light from the phosphor-containing regions. Blue, green and red light from the phosphors can be transmitted through the color wheel or reflected from the color wheel. In either case, blue, green and red light are collected by optics and redirected to the microdisplay. The UV light source may be a laser diode or an LED fabricated on non-polar or semi-polar oriented GaN. It is understood that other combinations of colored light sources and their color wheel are possible.

The light source as shown can be made based on lasers. In one embodiment, the output from the light source is a laser beam characterized by a substantially white color. In one embodiment, the light source combines light output from a blue laser diode, a green laser diode and a red laser diode. For example, blue, green, and red laser diodes can be integrated into a single package. As noted above, other combinations are also possible. For example, a blue laser diode and a green laser diode share a single package, and a red laser diode is packaged alone. In this embodiment, these lasers can be modulated so that the colors are time-sequential, thereby eliminating the need for a color wheel. Blue laser diodes can be polar, semi-polar and non-polar. Similarly, green laser diodes can be polar, semi-polar and non-polar. For example, blue diodes and/or green diodes are fabricated from bulk substrates comprising gallium nitride materials. For example, the following laser diode combinations are possible, but other combinations are also possible. Specifically, blue polar + green nonpolar + red *AlInGaP, blue polar + green semipolar + red *AlInGaP, blue polar + green polar + red *AlInGaP, blue semipolar + green nonpolar + red *AlInGaP, blue semi-polar + green semi-polar + red *AlInGaP, blue semi-polar + green polar + red *AlInGaP, blue non-polar + green non-polar + red *AlInGaP, blue non-polar + green semi-polar + red *AlInGaP, blue non-polar + green polarity + red * AlInGaP.

In FIG. 5, the DLP projection system uses a color wheel to project light of one color (eg, red, green, or blue) onto the DMD at a time. A color wheel is necessary because the light source provides continuous white light. It should be understood that the color wheel shown in FIG. 5 is not necessary in a DLP projector according to the present invention, since solid-state devices are used as light sources in embodiments of the present invention. FIG. 5-A is a simplified diagram illustrating a DLP projector according to an embodiment of the invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations.

In another embodiment, the light source includes a single laser diode. For example, the light source includes a blue laser diode that outputs a blue laser beam. The light source also includes one or more optical members that change the blue color of the laser beam, eg, the one or more optical members include phosphor material. The laser beam excites the phosphor material to form a substantially white light source that serves as the light source for the projection display. In this embodiment, a color wheel is required to order the blue, green and red frames for the DLP.

Projection system 500 includes light source 501 , light source controller 502 , optical member 504 and DLP chip 505 . Light source 501 is configured to emit colored light to DMD 503 through optical member 504 . More specifically, light source 501 includes a colored laser diode. For example, laser diodes include red laser diodes, blue laser diodes and green laser diodes. At a given time interval, a single laser diode is turned on and the other laser diodes are turned off, thereby emitting a single colored laser beam onto DMD 503 . Light source controller 502 provides control signals to light source 501 to switch the laser diodes on and off based on a predetermined frequency and sequence. For example, this laser diode switching is analogous to the function of the color wheel shown in FIG.

FIG. 6 is a simplified diagram illustrating a 3-chip DLP projection system according to an embodiment of the invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in FIG. 5, a 3-chip DLP projection system includes a light source, an optical element, multiple DMDs, and a color wheel system. As shown, each of these DMDs is associated with a particular color.

In various embodiments, the white light beam comprises a substantially white laser beam provided by a light source. In one embodiment, the output from the light source is a laser beam characterized by a substantially white color. In one embodiment, the light source combines light output from a blue laser diode, a green laser diode and a red laser diode. For example, as described above, blue, green, and red laser diodes can be integrated into a single package. Other combinations are also possible. For example, a blue laser diode and a green laser diode share a single package, and a red laser diode is packaged alone. Blue laser diodes can be polar, semi-polar and non-polar. Similarly, green laser diodes can be polar, semi-polar and non-polar. For example, blue and/or green diodes are fabricated from bulk substrates comprising gallium nitride materials. For example, the following laser diode combinations are possible, but other possibilities are also possible. Specifically, blue polar + green nonpolar + red *AlInGaP, blue polar + green semipolar + red *AlInGaP, blue polar + green polar + red *AlInGaP, blue semipolar + green nonpolar + red *AlInGaP, blue semi-polar + green semi-polar + red *AlInGaP, blue semi-polar + green polar + red *AlInGaP, blue non-polar + green non-polar + red *AlInGaP, blue non-polar + green semi-polar + red *AlInGaP, blue non-polar + green polarity + red * AlInGaP.

In another embodiment, the light source includes a single laser diode. For example, the light source includes a blue laser diode that outputs a blue laser beam. The light source also includes one or more optical elements that change the blue color of the laser beam. For example, one or more optical members include phosphor material.

It should be appreciated that the light source may include laser diodes and/or LEDs. In one embodiment, the light sources include laser diodes of different colors. For example, the light source may further include a phosphor material that changes the color of light emitted from the laser diode. In another embodiment, the light source includes one or more colored LEDs. In yet another embodiment, the light source includes both laser diodes and LEDs. For example, the light source may include phosphor materials to change the light color of laser diodes and/or LEDs.

In various embodiments, laser diodes are used for 3D display applications. Typically, 3D display systems rely on stereoscopic principles. In stereoscopic technology, a separate device is used for each user viewing a scene to provide different images to the user's left and right eyes. Examples of this technology are anaglyph images and polarized glasses. FIG. 7 is a simplified diagram showing a 3D display with polarized images filtered by polarized glasses. As shown, left and right eyes perceive different images through polarized glasses.

For traditional polarized glasses, RealD They often include circular polarized glasses used by Cinema® and are widely adopted in many theaters. Another type of image separation is provided by interference filter technology. For example, spatial interference filters in eyeglasses and projectors have become the dominant technology, hence the name. These filters divide the visible color spectrum into 6 narrow bands, 2 of which are in the red region, 2 of which are in the green region, and 2 of which are in the blue region (for illustrative purposes only). so we call them R1, R2, G1, G2, B1 and B2)). These R1, G1 and B1 bands are used for the image for one eye and R2, G2 and B2 for the image for the other eye. With this technique, the human eye is nearly imperceptible to such minute spectral differences. A full-color 3D image can be generated with only a small color difference between the two eyes. In some cases, this technique is called "super-anaglyph." This is because this technology is a sophisticated spectral multiplexing and is at the core of conventional anaglyph technology. In a specific example, the following set of wavelengths are used. For example, red 629 nm, green 532 nm, blue 446 nm for the left eye, and red 615 nm, green 518 nm, blue 432 nm for the right eye.

In various embodiments, the invention provides projection systems for projecting 3D images. In this system, laser diodes are used to provide the basic RGB colors. FIG. 8 is a simplified diagram illustrating a 3D projection system according to an embodiment of the invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in FIG. 8, the projection system includes projector 801 . Projector 801 is configured to project an associated image for one eye (eg, left eye). Projector 801 includes a first light source. A first light source includes a first set of laser diodes (ie, a red laser diode, a green laser diode, and a blue laser diode). Each of these laser diodes is associated with a specific wavelength. For example, a red laser diode is configured to emit a laser beam characterized by a wavelength of 629 nm, a green laser diode is configured to emit a laser beam characterized by a wavelength of 532 nm, and a blue laser diode is configured to emit a laser beam characterized by a wavelength of 532 nm. , configured to emit a laser beam characterized by a wavelength of 446 nm. It should be understood that other wavelengths are possible.

In various embodiments, blue laser diodes are characterized by a non-polar or semi-polar orientation. For example, blue laser diodes are made from gallium nitride containing substrates. In one particular embodiment, blue laser diodes are fabricated from bulk substrate material. Similarly, green laser diodes can also be fabricated from gallium nitride containing substrates. For example, green laser diodes are characterized by a non-polar or semi-polar orientation.

It should be understood that it is also possible to use colored LEDs to provide colored light to the projection element. For example, a red LED can be used instead of a red laser diode to provide red light. Similarly, various colored LEDs and/or laser diodes can be used interchangeably as light sources. Phosphor materials can be used to change the color of light emitted from LEDs and/or laser diodes.

Projector 802 is configured to project an associated image for the other eye (eg, right eye). A second light source includes a second set of laser diodes (ie, a red laser diode, a green laser diode, and a blue laser diode). Each of these laser diodes is associated with a specific wavelength, each of which differs from the wavelength of the corresponding laser diode of the first light source. For example, a red laser diode is configured to emit a laser beam characterized by a wavelength of 615 nm, a green laser diode is configured to emit a laser beam characterized by a wavelength of 518 nm, and a blue laser diode is configured to emit a laser beam characterized by a wavelength of It is configured to emit a laser beam characterized by 432nm. It should be understood that other wavelengths are possible.

Although the projectors 801 and 802 shown in FIG. 8 are arranged in a spaced apart manner, it should be understood that these two projectors can also be arranged together in one housing unit. In addition to the light source and image source, the projector contains optics for focusing the images from the two projectors onto the same screen.

Various types of filters can be used to filter the projected image to the viewer, depending on the particular application. In one embodiment, a bandpass filter is used. For example, a bandpass filter can allow only one set of RGB color wavelengths to pass through one eye. In another embodiment, a notch filter can be used to allow substantially all wavelengths to pass through one eye except for a specific set of RGB color wavelengths. Other embodiments are possible.

In certain embodiments, the present invention provides liquid crystal on silicon (LCOS) projection systems. FIG. 9 is a simplified diagram illustrating an LCOS projection system 900 according to an embodiment of the invention. This diagram is merely an example, which should not unduly limit the scope of the claims. Those skilled in the art will recognize modifications, substitutions and alterations. As shown in FIG. 9, the green laser diode provides green laser light to green LCOS through splitter 901, the blue laser diode provides blue laser light to blue LCOS through splitter 903, and the red laser diode provides red laser light. Provides light to LCOS through splitter 904 . Each LCOS is used to form an image of a given single color as provided by the corresponding laser diode, and the single colored images are combined by the x-cube component 902 . The combined color image is projected onto lens 906 .

In various embodiments, one or more laser diodes used in projection system 900 are characterized by a semi-polar or non-polar orientation. In one embodiment, the laser diode is manufactured from a bulk substrate. In certain embodiments, blue and green laser diodes are fabricated from gallium nitride-containing substrates. It should be understood that it is also possible to use colored LEDs to provide colored light for the projection elements. For example, in providing red light, it is possible to use a red LED instead of a red laser diode. Similarly, various colored LEDs and/or laser diodes can be used interchangeably as light sources. Phosphor materials can be used to change the color of light emitted from LEDs and/or laser diodes.

LCOS projection system 900 includes three panels. In another embodiment, the invention provides a projection system with a single LCOS panel. Red, green and blue laser diodes are aligned and the red, green and blue laser beams are collimated onto a single LCOS. The laser diodes are pulse modulated so that only one laser diode is powered at a given time and the LCOS illuminates in a single color. It will be appreciated that due to the use of colored laser diodes, beamsplitters to split a single white light source into colored beams as used in conventional LCOS projection systems are not required in the LCOS projection system according to the present invention. should. In various embodiments, one or more laser diodes used in a single LCOS projection system are characterized by semi-polar or non-polar orientations. In one embodiment, the laser diode is manufactured from a bulk substrate. In certain embodiments, blue and green laser diodes are fabricated from gallium nitride-containing substrates. In various embodiments, the configuration shown in FIG. 9 is also used in ferroelectric liquid crystal on silicon (FLCOS) systems. For example, the panel shown in Figure 9 can be a FLCOS panel.

Although specific embodiments have been detailed above, various modifications, alternative constructions, and changes to equivalents are possible. Therefore, the above description and illustrations should not be taken as limiting the scope of the invention. The scope of the invention is defined and construed by the following claims.