Projection type display device and display device and its driving method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a projection type display device and a display device and a driving method thereof. The projection type display device and the display device and the display device thereof are particularly excellent in image expressive power and can obtain an image having a brightness suitable for a usage environment and a user's preference. It relates to a driving method.

【0002】

[Conventional technology]

In recent years, the development of information devices has been remarkable, and the demand for thin display devices with high resolution, low power consumption, has increased, and research and development are being promoted. Among them, the liquid crystal display device is expected as a display device capable of electrically controlling the arrangement of liquid crystal molecules to change the optical characteristics and meeting the above needs. As one form of such a liquid crystal display device, a projection type liquid crystal display device (liquid crystal projector) that magnifies and projects an image emitted from an optical system using a liquid crystal light valve onto a screen through a projection lens is known.

【0003】

[Problems to be Solved by the Invention]

The projection type liquid crystal display device uses a liquid crystal light valve as a light modulation means, and the projection type display device includes a digital mirror device (hereinafter abbreviated as DMD) in addition to the liquid crystal light valve. Those used as optical modulation means have also been put into practical use. However, this type of conventional projection display device has the following problems.

【0004】

(1) Sufficient contrast cannot be obtained due to light leakage and stray light generated by various optical elements that make up the optical system. Therefore, the gradation range (dynamic range) that can be displayed is narrow, and it is inferior in terms of image quality and power compared to existing TV receivers that use cathode ray tubes (hereinafter abbreviated as CRT). It ends up.

【0005】

(2) Even if an attempt is made to improve the quality of video by various video signal processing, the dynamic range is fixed, so that a sufficient effect cannot be exhibited.

【0006】

As a solution to such a problem of the projection type display device, that is, a method of expanding the dynamic range, it is conceivable to change the amount of light incident on the light modulation means (light bulb) according to the video signal. The simplest way to achieve this is to change the light output intensity of the lamp. A method of controlling the output light of a metal halide lamp in a projection type liquid crystal display device is disclosed in Japanese Patent Application Laid-Open No. 3-179886.

【0007】

However, although high-pressure mercury lamps are currently the mainstream lamps used in projection-type liquid crystal display devices, it is extremely difficult to control the light output intensity with high-pressure mercury lamps. Therefore, there is a demand for a method capable of changing the amount of light incident on the light modulation means according to the video signal without changing the light output intensity of the lamp itself.

【0008】

Furthermore, in addition to the above problems, since the brightness of the light source is fixed in the current projection type display device, the screen becomes too bright in a dark viewing environment, for example, and the projection distance and the zooming of the projection lens There is also a problem that when the projection screen size is changed, the brightness of the screen changes accordingly.

【0009】

The present invention has been made to solve the above problems, and it is possible to change the amount of incident light to the light modulation means without changing the light output intensity of the lamp, and it is possible to improve the image expressiveness and the usage environment. It is an object of the present invention to provide a projection type display device or a display device capable of exerting an excellent effect in terms of adaptability.

【0010】

[Means for solving problems]

In order to achieve the above object, the projection type display device of the present invention projects a lighting means, a light modulation means for modulating the light emitted from the lighting means, and a light modulated by the light modulation means. A projection type display device including a projection means, the illumination means includes a light source, a uniform illumination means for equalizing the illuminance distribution of light incident from the light source, and an optical axis of light emitted from the light source. It is equipped with a dimming liquid crystal element that is installed above and adjusts the intensity of the emitted light from the light source, and the uniform illumination is performed by changing the voltage applied to the dimming liquid crystal element based on information from the outside. It is characterized in that the amount of light emitted from the means can be adjusted.

【0011】

The present inventor presents the present invention as a means for adjusting the amount of light incident on the light modulation means according to the image without changing the light output intensity of the light source, as compared with the lighting device of the conventional projection type display device. , It has been found that a dimming liquid crystal element capable of adjusting the amount of transmitted light based on information from the outside should be added. The above "information from the outside" includes, for example, information based on the video signal supplied to the optical modulation means, information based on the projection magnification, information based on the brightness situation under the usage environment, and user's preference. Information based on this can be mentioned.

【0012】

That is, according to the projection type display device of the present invention, a dimming liquid crystal element for adjusting the intensity of the emitted light from the light source is provided, and the dimming liquid crystal element is controlled based on the information from the outside. Because of the configuration, when used in a projection type display device, due to the action of the dimming liquid crystal element, for example, when the information from the outside is information based on a video signal, it is adjusted according to the brightness of the scene at that time. The voltage applied to the optical liquid crystal element is changed, the intensity of the emitted light from the light source is adjusted by the applied voltage value, and the amount of light emitted from the lighting means to the light modulation means is adjusted. For example, when a voltage is applied to a dimming liquid crystal element with a normal white display, the transmittance is controlled in the range of 100% to a value close to 0% by controlling the magnitude of the voltage applied per frame. Can be changed freely. In addition, by changing the transmittance in the range of 100% to a value close to 0% in this way, the amount of light emitted from the dimming liquid crystal element can be changed, so the applied voltage can be lowered in bright situations. By increasing the transmittance, the amount of light is increased, and in a dark scene, the applied voltage is increased, and by decreasing the transmittance, the amount of light is decreased, so that the light is emitted from the light source. The light intensity is adjusted by this dimming liquid crystal element. In this way, even if the light output intensity of the light source remains constant, the light modulation means can obtain light having a brightness corresponding to the image, which can contribute to the expansion of the dynamic range of the projection type display device. Similarly, it is possible to obtain light having a brightness according to the projection magnification, the state of brightness under the usage environment, the preference of the user, and the like.

【0013】

Therefore, according to the projection type display device of the present invention having the above configuration, the amount of light emitted from the uniform lighting means by changing the voltage applied to the dimming liquid crystal element based on information from the outside. Since a lighting device that can adjust the light intensity is provided, light of a desired intensity can be obtained by the light modulation means even if the light output intensity of the light source remains constant, so that the dynamic range of the projection type display device can be expanded. , It is possible to realize a projection type display device having excellent image expressiveness and adaptability to the usage environment.

【0014】

By the way, when the intensity of the emitted light from the light source is adjusted by using the dimming liquid crystal element as described above, the white balance of the light emitted from the dimming liquid crystal element to the light modulation means changes. In other words, the light emitted from the dimming liquid crystal element to the light modulation means may be colored. This is because the liquid crystal element used as the dimming means utilizes the birefringence of the liquid crystal, so that the transmittance of the liquid crystal element differs depending on the applied voltage and exhibits wavelength dependence. When the light emitted from the dimming liquid crystal element to the optical modulation means is colored, the light emitted from the light modulation means is also affected, so that the image obtained by projecting this light is also affected. It ends up. Therefore, in the projection type display device of the present invention, the voltage applied to the optical modulation means is changed based on the voltage applied to the dimming liquid crystal element, or the voltage application period of the optical modulation means is changed. It is preferable to have a configuration in which the light emitted from the dimming liquid crystal element can be color-corrected by the light modulation means. As a projection type display device having a configuration in which the light emitted from the dimming liquid crystal element can be color-corrected by the light modulation means, the voltage value applied to the dimming liquid crystal element and the dimming With the correction voltage value applied to the optical modulation means to correct the color tone of the light emitted from the dimming liquid crystal element according to the voltage value applied to the liquid crystal element, or the correction coefficient for calculating the correction period. A storage means for storing the color tone correction table showing the relationship is provided, and the correction applied to the optical modulation means from the color tone correction table stored in the storage means according to the voltage applied to the dimming liquid crystal element. The coefficient is selected and determined, and the voltage applied to the optical modulation means can be changed or the application period of the voltage applied to the optical modulation means can be changed based on the determined correction coefficient. Is preferable.

【0015】

Since the relationship between the voltage applied to the dimming liquid crystal element and the transmission rate is known, and the relationship between the applied voltage and the white balance of the light emitted from the dimming liquid crystal element is also known, it is for dimming. Calculate the correction voltage value or correction voltage application period applied to the optical modulation means in order to correct the light emitted from the dimming liquid crystal element at each voltage value so that the desired white balance is obtained. A color tone correction table is stored in the storage means in advance so that the correction coefficient for the correction can be known. A correction coefficient to be applied to the optical modulation means according to the voltage value applied to the dimming liquid crystal element is selected and determined on the color tone correction table, and the determined correction coefficient is applied to the optical modulation means. The light emitted from the dimming liquid crystal element can be color-corrected by the light modulation means, and the coloring of the light emitted from the dimming liquid crystal element affects the light emitted from the light modulation means. Can be prevented. The color tone correction table shows, for example, a correction voltage value applied to the optical modulation means for color tone correction or a correction coefficient for calculating the correction voltage application period with respect to the voltage applied to the dimming liquid crystal element. The voltage applied to the dimming liquid crystal element, the chromaticity coordinate value of the light transmitted through the dimming liquid crystal element with respect to the voltage value, and for chromaticity correction for this chromaticity coordinate. Examples thereof include a correction voltage value applied to the optical modulation means or a correction coefficient for calculating the correction voltage application period.

【0016】

Therefore, according to the projection type display device of the present invention having the above configuration, the amount of light emitted from the uniform lighting means by changing the voltage applied to the dimming liquid crystal element based on information from the outside. Can be adjusted. Moreover, the color tone can be corrected by changing the voltage applied to the optical modulation means according to the voltage applied to the dimming liquid crystal element or changing the application period of the voltage applied to the light modulation means. Even if the light output intensity of the light source remains constant, it is possible to obtain light having a desired brightness in the light modulation means and having the white balance corrected. Therefore, the dynamic range of the projection type display device can be expanded, which is advantageous for realizing a projection type display device having excellent image expressiveness and adaptability to the usage environment.

【0017】

As a specific form of the dimming liquid crystal element, a liquid crystal layer is sandwiched between a pair of light transmissive substrates, and light transmissive electrodes are formed on the surfaces of the pair of light transmissive substrates on the liquid crystal layer side. Further, those having a liquid crystal panel in which an alignment film is formed on the surface of each of these light-transmitting electrodes on the liquid crystal layer side can be preferably used, and the liquid crystal panel includes a TN (Twisted Nematic) method. STN (Super Twisted Nematic) method, VA (Vertical Alignment), OCB (Optically Compensated Bend) method, IPS (In-Plane Switching), etc. can be used, and in particular, the operation of this dimming liquid crystal element. When the mode is a TN (Twisted Nematic) method, it is preferable to use the normal white method.

【0018】

As a specific form of the uniform illumination means, it is composed of two fly-eye lenses including a first fly-eye lens and a second fly-eye lens which are sequentially arranged along the optical axis from the side closer to the light source. It may be the one that is. In this way, in the uniform illumination means composed of two fly-eye lenses, a plurality of secondary light source images are formed by the first fly-eye lens, and the plurality of secondary light source images are optically modulated through the second fly-eye lens. By superimposing on the top, the illuminance distribution of the original light source can be made uniform. When the uniform illumination means is composed of the first fly-eye lens and the second fly-eye lens in this way, not only the amount of light that illuminates the entire illuminated area of the light modulation means is adjusted, but also the light modulation means of the light modulation means. When the illuminated area is divided into a plurality of areas, it is possible to adjust the amount of light that illuminates each area. According to such a configuration, the illuminance distribution in the optical modulation means can be made more detailed and uniform.

【0019】

Further, as another specific form of the uniform illumination means, a rod-shaped light guide body may be used in which the light flux from the light source is divided into a plurality of light fluxes and emitted by utilizing reflection. As a specific form of the rod-shaped light guide, a rod lens or the like can be used. When the uniform illumination means is a rod-shaped light guide as described above, not only the amount of light that illuminates the entire illuminated area of the light modulation means is adjusted, but also the illuminated area of the light modulation means is divided into a plurality of areas. It is also possible to easily adjust the amount of light that illuminates each area when divided. According to such a configuration, the illuminance distribution in the optical modulation means can be controlled.

【0020】

The display device of the present invention is a display device having a lighting means and a light modulation means for modulating light emitted from the lighting means, and the lighting means is a light source and light incident from the light source. Information from the outside is provided with a uniform lighting means for making the illuminance distribution uniform and a dimming liquid crystal element installed on the optical axis of the light emitted from the light source and adjusting the intensity of the emitted light from the light source. The light amount emitted from the uniform lighting means can be adjusted by changing the voltage applied to the dimming liquid crystal element based on the above. According to this display device, since the lighting means capable of adjusting the amount of light emitted from the uniform lighting means by changing the voltage applied to the light liquid crystal element based on the information from the outside is provided. Even if the light output intensity of the light source remains constant, the light with the desired brightness can be obtained by the light modulation means, so that the dynamic range of the projection type display device can be expanded, and the image expressiveness and adaptability to the usage environment can be improved. An excellent display device can be realized.

【0021】

Further, the display device of the present invention photomodulates the light emitted from the dimming liquid crystal element by changing the voltage applied to the optical modulation means based on the voltage applied to the dimming liquid crystal element. It is preferable that the configuration is such that the color tone can be corrected by means. Further, the display device of the present invention photomodulates the light emitted from the dimming liquid crystal element by changing the voltage application period of the optical modulation means based on the voltage applied to the dimming liquid crystal element. It is preferable that the configuration is such that the color tone can be corrected by means. As a display device having a configuration in which the light emitted from such a dimming liquid crystal element can be color-corrected by the light modulation means, the voltage value applied to the dimming liquid crystal element and the dimming liquid crystal element The relationship between the correction voltage value applied to the optical modulation means to correct the color tone of the light emitted from the dimming liquid crystal element or the correction coefficient for calculating the correction period according to the voltage value applied to the light is shown. A storage means for storing the color tone correction table is provided, and a correction coefficient to be applied to the light modulation means is selected from the color tone correction table stored in the storage means according to the voltage applied to the light control liquid crystal element. ,It is determined. The light emitted from the dimming liquid crystal element is converted into the light by changing the voltage applied to the optical modulation means based on the determined correction coefficient or changing the applied voltage period of the optical modulation means. It is preferable that the configuration is such that the color tone can be corrected by the modulation means.

【0022】

Further, as a control means of the projection type display device or the display device of the present invention having any of the above configurations, a control signal determining means for determining a control signal for controlling the dimming liquid crystal element based on a video signal, and the above-mentioned control signal determining means. It is desirable to provide a dimming control means for controlling the dimming liquid crystal element based on the control signal. According to this configuration, the control signal determining means first determines the brightness control signal for controlling the dimming liquid crystal element based on the video signal, and the dimming control means determines the dimming liquid crystal based on these control signals. By controlling the voltage value applied to the element, light whose brightness changes according to the image is supplied to the optical modulation means. By this operation, the dynamic range of the projection type display device or display device can be expanded, and the projection type display device or display device having excellent image expressiveness and adaptability to the usage environment can be realized.

【0023】

In the projection type display device or the control means of the display device of the present invention having any of the above configurations, depending on the voltage applied to the dimming liquid crystal element corresponding to the control signal for controlling the dimming liquid crystal element. An optical modulation control signal determining means that selects and determines a correction coefficient of a voltage applied to the optical modulation means from the color tone correction table, and determines a control signal for controlling the optical modulation means based on the determined correction coefficient. And, it is preferable that the optical modulation control means for controlling the optical modulation means based on the control signal determined by the optical modulation control signal determination means is provided. In the optical modulation control signal determining means, the correction coefficient applied to the optical modulation means according to the voltage applied to the dimming liquid crystal element corresponding to the control signal for controlling the dimming liquid crystal element from the color tone correction table. Is selected and determined, the control signal for controlling the optical modulation means is determined based on the determined correction coefficient, and the optical modulation control means is based on the control signal determined by the optical modulation control signal determination means. The voltage applied to the optical modulation means is controlled, or the applied voltage period of the optical modulation means is controlled. By this operation, the color tone of the light emitted from the dimming liquid crystal element to the light modulation means can be corrected.

【0024】

The method for driving the projection type display device or display device of the present invention is the method for driving the projection type display device or display device having the above configuration, and determines a control signal for controlling the dimming liquid crystal element based on a video signal. It is characterized in that the amount of light that illuminates the light modulation means is adjusted by controlling the dimming liquid crystal element based on the control signal. According to this configuration, the dynamic range of the projection type display device or the display device can be expanded, and an image having high image expressive power can be obtained.

【0025】

In the projection type display device or the driving method of the display device having the above configuration, the light is stored in the storage means according to the voltage applied to the dimming liquid crystal element corresponding to the control signal for controlling the dimming liquid crystal element. A correction coefficient to be applied to the optical modulation means is selected and determined from the color tone correction table, a control signal for controlling the optical modulation means is determined based on the determined correction coefficient, and the control signal is used as the basis for the control signal. It is preferable that the light emitted from the dimming liquid crystal element is color-corrected by the light modulation means by controlling the light modulation means. According to this method, the color tone of the light emitted from the dimming liquid crystal element to the light modulation means can be corrected, so that the light emitted from the light modulation means is produced by coloring the light emitted from the dimming liquid crystal element. It is advantageous because it can prevent the influence.

【0026】

BEST MODE FOR CARRYING OUT THE INVENTION

[Projection Type Display Device] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a projection type liquid crystal display device, which is an example of the projection type display device of the present invention, will be described with reference to FIGS. 1 to 6. The projection type liquid crystal display device of the present embodiment is a three-plate type projection type color liquid crystal display device provided with a transmissive liquid crystal light bulb for each of different colors of R (red), G (green), and B (blue). .. FIG. 1 is a schematic configuration diagram showing this projection type liquid crystal display device. In the figure, reference numeral 1 is a lighting device, 2 is a light source, 3 and 4 are fly-eye lenses (uniform lighting means), and 5d is a polarization conversion device. 5 is a liquid crystal element for dimming, 13,14 is a dichroic mirror, 15,16,17 is a reflection mirror, 22,23,24 is a liquid crystal light valve (light modulation means), 25 is a cross dichroic prism, 26 is a projection lens ( Projection means) is shown.

【0027】

The illumination device 1 in the present embodiment includes a light source 2, fly-eye lenses 3 and 4, a polarization conversion device 5d, and a dimming liquid crystal element 5. The light source 2 is composed of a lamp 7 such as a high-pressure mercury lamp and a reflector 8 that reflects the light of the lamp 7. Further, as a uniform illumination means for making the illuminance distribution of the light source light uniform in the liquid crystal light bulbs 22, 23, 24 which are the illuminated areas, the first fly-eye lens 3 and the second fly-eye lens 4 are provided from the light source 2 side. It is installed in sequence. Each of the fly-eye lenses 3 and 4 is composed of a plurality of lenses 9 and 10 (for example, 6 × 8 in the present embodiment), and the illuminance distribution of the light emitted from the light source 2 is a liquid crystal in the illuminated area. It functions as a uniform lighting means for homogenizing in the light bulb. Light is emitted from the uniform illumination means to the dimming liquid crystal element 5 via the polarization conversion device 5d. In the case of the present embodiment, a dimming liquid crystal element 5 is installed as a dimming means for adjusting the amount of light emitted from the light source 2.

【0028】

The polarization converter 5d is composed of a polarization beam splitter array (PBS array) provided on the uniform illumination means side and a 1/2 wave plate array provided on the dimming liquid crystal element 5 side. The polarization conversion device 5d is provided between the uniform lighting means and the dimming liquid crystal element 5. In the dimming liquid crystal element 5, a liquid crystal layer is sandwiched between a pair of glass substrates (light transmissive substrates), and light transmissive electrodes are formed on the surfaces of the pair of glass substrates on the liquid crystal layer side, respectively. It is roughly composed of a liquid crystal panel 5a in which an alignment film is formed on the surface of the transmissive electrode on the liquid crystal layer side, and polarizing plates 5b and 5c laminated on both sides of the liquid crystal panel 5a. As the liquid crystal sandwiched between the pair of glass substrates, the above-mentioned TN method or the like is used. Of the polarizing plates 5b and 5c, at least the polarizing plate 5c provided on the light emitting side preferably has high light resistance. The polarizing plate 5c having such light resistance has a structural birefringence in which a plurality of Al (aluminum) ribs arranged in stripes at a pitch smaller than the wavelength of light incident on the liquid crystal layer are provided on the surface on the incident side. A mold is suitable. The polarizing plate 5c provided with such a plurality of light reflectors can transmit only specific polarized light and reflect only specific polarized light. The dimming liquid crystal element 5 having the above configuration is arranged between the uniform lighting means and the dichroic mirror 13 described later.

【0029】

This dimming liquid crystal element 5 receives a drive signal from the dimming element driver 34 described later and applies a voltage to the light transmissive electrode. If the magnitude of the applied voltage is changed, the transmittance becomes 0%. The transmittance can be freely changed in the range of close to 100%, and by changing the transmittance in the range of close to 0% to 100% in this way, from the dimming liquid crystal element 5 Since the amount of emitted light can be changed, the applied voltage is lowered to increase the transmittance in bright scenes, and the applied voltage is increased to lower the transmittance in dark scenes from the light source 2. The intensity of the emitted light is adjusted by this dimming liquid crystal element 5.

【0030】

The configuration of the latter stage of the lighting device 1 will be described below together with the operation of each component. The dichroic mirror 13 that reflects blue light and green light transmits the red light LR of the light sources from the light source 2 and reflects the blue light LB and the green light LG. The red light LR transmitted through the dichroic mirror 13 is reflected by the reflection mirror 17 and incident on the red light liquid crystal light valve 22.

【0031】

On the other hand, of the colored light reflected by the dichroic mirror 13, the green light LG is reflected by the dichroic mirror 14 for reflecting green light and is incident on the liquid crystal light valve 23 for green light. On the other hand, the blue light LB also transmits the dichroic mirror 14, and is incident on the liquid crystal light valve 24 for blue light via the relay system 21 including the relay lens 18, the reflection mirror 15, the relay lens 19, the reflection mirror 16, and the relay lens 20. ..

【0032】

The projection type display device 30 of the present embodiment is provided with a storage means 39 in which a color tone correction table, which will be described in detail later, is stored. This color tone correction table corrects the color tone of the light emitted from the dimming liquid crystal element 5 according to the voltage value applied to the dimming liquid crystal element 5 and the voltage value applied to the dimming liquid crystal element 5. Therefore, the relationship with the correction voltage value applied to each of the liquid crystal light valves 22, 23, 24 or the correction coefficient for calculating the correction period is shown. Then, in the projection type display device 30, the correction coefficient to be applied to each of the above liquid crystal light valves 22, 23, 24 is selected and determined from the color tone correction table stored in the storage means 36, and the determined correction coefficient is selected. The voltage applied to each liquid crystal light valve 22,23,24 is changed by correcting the voltage applied to each liquid crystal light valve 22,23,24 based on, or the voltage applied to each liquid crystal light valve 22,23,24 is changed. By correcting the applied voltage period, the applied voltage period of each liquid crystal light valve 22,23,24 can be changed, and the corrected voltage or the corrected period voltage can be applied to each liquid crystal light valve 22,23,24 (white balance). It has a structure that can be corrected).

【0033】

It is known that the relationship between the applied voltage and the white balance of the light emitted from the dimming liquid crystal element 5 is as shown in the example shown in FIG. FIG. 6 shows an example of the relationship between the voltage applied to the dimming liquid crystal element and the white balance of the light emitted from the dimming liquid crystal element (light transmitted through the dimming liquid crystal element). It is a systematic chromaticity diagram. In FIG. 6, point O is a point when the light emitted from the dimming liquid crystal element is not colored. When the dimming liquid crystal element is of the normal white method, it is applied when the color of the light emitted from the dimming liquid crystal element is uncolored white (achromatic color) (point O in FIG. 6). When a voltage larger than the voltage value is applied, the color changes from achromatic to bluish. When the dimming liquid crystal element is of the normal black method, the voltage applied when the color of the light emitted from the dimming liquid crystal element is uncolored white (achromatic color) (point O in FIG. 6). When a voltage larger than the value is applied, the color changes from achromatic to yellowish.

【0034】

Therefore, in order to correct the light emitted from the dimming liquid crystal element 5 so as to have a desired white balance when the dimming liquid crystal element 5 has each voltage value, the liquid crystal light valves 22, 23, 24 are used. A color tone correction table showing the correction voltage value to be applied or the correction coefficient for calculating the correction period is stored in the storage means in advance, and the color tone correction is performed according to the voltage applied to the dimming liquid crystal element 5. Select and determine the correction coefficient to be applied to each liquid crystal light valve 22, 23, 24 from the table, and correct the applied voltage of each liquid crystal light valve 22, 23, 24 based on this determined correction coefficient, or each By correcting the applied voltage periods of the liquid crystal light valves 22, 23, and 24, the color tone of the projected image can be corrected.

【0035】

As a color tone correction table, for example, when the voltage applied to the dimming liquid crystal element 5 is each voltage value, the correction voltage value applied to the liquid crystal light valves 22, 23, 24 for color tone correction is calculated. The following Table 1 showing the correction coefficient can be mentioned.

【0036】

"table 1" Liquid crystal element for dimming For R For G For B The voltage applied to the light bulb of the light bulb of the light bulb (v) Correction coefficient Correction coefficient Correction coefficient 0 1 1 1 5 1 1 0.8 [0037]

In Table 1, the light bulb for R shows the liquid crystal light bulb 22 for red light, the light bulb for G shows the liquid crystal light bulb 23 for green light, and the light bulb for B shows the liquid crystal light bulb 24 for blue light.

【0038】

For example, when the dimming liquid crystal element 5 is of the normal white method and a voltage is applied to the dimming liquid crystal element 5, the transmittance is, for example, about 10% when the applied voltage is 5V. At this time, the emitted light from the dimming liquid crystal element 5 is colored blue. In such a case, the correction coefficient applied to the liquid crystal light valve 24 for blue light from the color tone correction table shown in Table 1 above is multiplied by 0.8, and the liquid crystal light valve 22 for red light and the liquid crystal light valve 23 for green light are applied respectively. Dimming by setting the correction coefficient to 1 and applying a correction voltage to each liquid crystal light valve 22,23,24 based on these correction coefficients, or by correcting the voltage application period of each liquid crystal light valve 22,23,24. Corrects the white balance of the emitted light from the liquid crystal element 5. The example of the color tone correction table is not limited to the example shown in Table 1 above, but the voltage applied to the dimming liquid crystal element and the output from the dimming liquid crystal element at each voltage value. Correction to calculate the chromaticity coordinates of the light (light transmitted through the dimming liquid crystal element) and the correction voltage value or correction period applied to the light modulation means for chromaticity correction for these chromaticity coordinates. Examples thereof include those showing a coefficient.

【0039】

The three colored lights modulated by each of the liquid crystal light bulbs 22, 23, 24 are incident on the cross dichroic prism 25. In this prism, four right-angled prisms are bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof. Three colored lights are combined by these dielectric multilayer films to form light representing a color image. The combined light is projected onto the screen 27 by the projection lens 26, which is a projection optical system, and an enlarged image is displayed.

【0040】

Next, a driving method of the projection type liquid crystal display device 30 of the present embodiment will be described. FIG. 2 is a block diagram showing a configuration of a drive circuit of the projection type liquid crystal display device 30 of the present embodiment. In the case of a conventional projection type liquid crystal display device that does not have a dimming function, the input video signal undergoes appropriate correction processing and is supplied to the liquid crystal panel driver as it is, but it has a dimming function and a color tone correction function. In addition, in the case of the present embodiment in which it is controlled based on a video signal, as a basic configuration, as described below, circuits such as DSP (1) to DSP (3), which are digital signal processing blocks, and color tones. A ROM (storage means) in which the correction table is stored is required.

【0041】

In the present embodiment, as shown in FIG. 2, a video signal input as an analog signal is input to DSP (1) 32 (control signal determining means), which is a first digital signal processing circuit, via an AD converter 31. To. In DSP (1) 32, the voltage value applied to the dimming liquid crystal element 5 from the video signal, that is, the brightness control signal that determines the transmittance of the dimming liquid crystal element is determined. The brightness control signal determined by DSP (1) 32 is input to DSP (2) 33 (dimming control means). The brightness control signal determined by DSP (1) 32 is also input to DSP (3) 36 together with the video signal. The above video signal input to the DSP (3) 36 is converted into an analog signal again by the DA converter 37, and then input to the panel driver 38. From the panel driver 38, the liquid crystal light valve 22 for red light and the green light are used. It is supplied to each of the liquid crystal light valve 23 and the liquid crystal light valve 24 for blue light.

【0042】

The DSP (2) 33 (dimming control means) controls the dimming element driver 34 based on the brightness control signal determined by the DSP (1) 32, and finally the dimming element driver 34 dims. Drives the liquid crystal element 5.

【0043】

The voltage value applied to the dimming liquid crystal element 5 is input from the dimming element driver 34 to the ROM (storage means) 39 in which the color tone correction table is stored. Then, in the DSP (3) 36 (optical modulation signal determining means and optical modulation control means) connected to the ROM (storage means) 39, each liquid crystal light valve 22 is applied according to the voltage applied to the dimming liquid crystal element 5. A white balance control signal (control signal) that selects and determines the correction coefficient to be applied to, 23, 24 from the above color tone correction table and controls each liquid crystal light valve 22, 23, 24 based on the determined correction coefficient. To determine. This white balance control signal is input to the DA converter 37 and further input to the panel driver 38 to control the panel driver 38, and finally the panel driver 38 controls each liquid crystal light valve 22 based on the white balance control signal. , 23, 24 is applied with a correction voltage value, or the period during which a voltage is applied to each liquid crystal light valve 22, 23, 24 is corrected and driven. The above-mentioned operation corrects the above-mentioned video signal, and it is possible to realize smooth gradation expression while expanding the dynamic range of the video.

【0044】

Here, regarding the control method of the lighting device 1, in addition to [1] display image adaptive control, [2] control by projection magnification, [3] control from the outside, and the like can be considered. Each method will be described below.

[1] Display image adaptive control First, consider a case where display image adaptive control, that is, brightness control adapted to a display image such that the amount of light increases in a bright scene and decreases in a dark scene. In this case, as described above, the DSP (1) 32 determines the brightness control signal based on the video signal, and the following three methods can be considered, for example.

【0045】

(a) A method in which the gradation value having the maximum brightness among the pixel data included in the frame of interest is used as the brightness control signal. For example, assume a video signal containing 256 steps of gradation values from 0 to 255. When focusing on any one frame that constitutes a continuous image, it is assumed that the appearance frequency distribution (histogram) for each gradation value of the pixel data included in that frame is as shown in FIG. In the case of this figure, the brightest gradation value included in the histogram is 190, so this gradation value 190 is used as the brightness control signal. This method is a method that can express the brightness most faithfully to the input video signal.

【0046】

(b) From the appearance frequency distribution (histogram) for each gradation value included in the frame of interest, the brightness is the gradation value that is a constant ratio (for example, 10%) from the maximum brightness to the appearance frequency. How to use as a control signal. For example, when the appearance number distribution of the video signal is as shown in Fig. 4, the area of 10% is taken from the brighter side than the histogram. Assuming that the gradation value corresponding to 10% is 230, this gradation value 230 is used as the brightness control signal. When there is a sudden peak in the vicinity of the gradation value 255 as shown in the histogram of FIG. 4, if the method (a) above is adopted, the gradation value 255 becomes the brightness control signal. However, this sudden peak part does not make much sense as information on the entire screen. On the other hand, this method in which the gradation value 230 is used as the brightness control signal can be said to be a method of determining by a region having meaning as information in the entire screen. The above ratio may be changed in the range of about 1 to 50%.

【0047】

(c) A method in which the screen is divided into a plurality of blocks, the average value of the gradation values of the pixels included in each block is calculated, and the maximum value is used as the brightness control signal. For example, as shown in Fig. 5, the screen is divided into m × n blocks, and the average value of the brightness (gradation value) for each block A11, ..., Amn is calculated, and the maximum value is calculated. Let the thing be a brightness control signal. It is desirable that the number of screen divisions is about 6 to 200. This method is a method that can control the brightness without damaging the atmosphere of the entire screen. Regarding the above methods (a) to (c), in addition to determining the brightness control signal for the entire display area, the above method may be applied only to a specific part such as the central part of the display area. it can. In this case, it is possible to control the brightness from the part that the viewer is paying attention to.

【0048】

Next, the DSP (2) 33 controls the dimming element driver 34 based on the brightness control signal determined by the above method. For this method, for example, the following two methods can be considered.

【0049】

(a) A method of controlling in real time according to the output brightness control signal. In this case, since the brightness control signal output from the DSP (1) 32 may be supplied to the dimming element driver 34 as it is, the signal processing by the DSP (2) 33 becomes unnecessary. This method is ideal because it completely follows the brightness of the image, but the brightness of the screen may change in a short cycle depending on the content of the image, causing problems such as feeling extra stress when viewing. There is a fear.

【0050】

(b) A method of applying an LPF (low-pass filter) to the output brightness control signal and controlling it with the output. For example, the LPF cuts the change in the brightness control signal for 1 to 30 seconds or less, and controls it by its output. According to this method, since a small change in time is cut, it is possible to avoid the change in brightness in a short cycle as described above.

【0051】

[2] Control by projection magnification It is controlled in correspondence with the zooming of the projection lens 26. Normally, since the amount of light per unit area in the liquid crystal light bulb (illuminated area) is constant, the screen tends to be dark on the enlargement side and bright on the reduction side. Therefore, in order to correct this, the dimming liquid crystal element 5 is controlled so that the amount of light increases when it is changed to the enlargement side and decreases when it is changed to the reduction side.

【0052】

[3] External control Allow the user to control the dimming liquid crystal element 5 according to his / her preference. For example, the dimming liquid crystal element 5 is controlled so that the amount of light is small in a dark viewing environment and the amount of light is large in a bright viewing environment. In this case, the configuration may be such that the user adjusts by using a controller or by directly operating the dimming liquid crystal element, or may be configured to be automatically controlled by providing a brightness sensor or the like. However, in order to control these [2] and [3], the circuits such as DSP (1) 32 to DSP (3) 36 in Fig. 2 are not required, but other circuit configurations are required. is there.

【0053】

According to the projection type display device 30 of the present embodiment, the amount of light emitted from the uniform lighting means can be adjusted by changing the voltage applied to the light liquid crystal element 5 based on information from the outside. Since the color tone can be corrected by changing the voltage applied to the liquid crystal light valve based on the signal supplied to the dimming liquid crystal element 5 or by changing the applied voltage period of the liquid crystal light valve, the light output of the light source Even if the intensity remains constant, the light with the desired brightness and white balance corrected can be obtained with the liquid crystal light valve, so the dynamic range of the projection type display device can be expanded, and the image expressiveness and usage environment can be improved. It is advantageous for realizing a projection type display device having excellent adaptability.

【0054】

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the uniform illumination means is not limited to the fly-eye lenses 3 and 4 as in the above embodiment, and can be appropriately changed, and a rod-shaped light guide such as a rod lens can also be used. Further, in the above embodiment, an example of a projection type liquid crystal display device using a liquid crystal light valve as the light modulation means has been given, but the present invention can also be applied to a projection type display device using DMD as the light modulation means. Is. Further, in the above-described embodiment, the case where the present invention is applied to a projection type display device has been described, but it can also be applied to a direct-view type display device. Further, in the above embodiment, the case of adjusting the amount of light that illuminates the entire illuminated area of the liquid crystal light bulb (light modulation means) has been mainly described, but when the liquid crystal light bulb is divided into a plurality of areas, each area is described. It is also possible to adjust the amount of light that illuminates each [0055]

[Effect of the invention]

As described in detail above, according to the projection type display device or display device of the present invention, the light is emitted from the uniform lighting means by changing the voltage applied to the light liquid crystal element based on information from the outside. Since a lighting device capable of adjusting the amount of light is provided, light of a desired brightness can be obtained by the light modulation means even if the light output intensity of the light source remains constant. Therefore, the dynamic range of the projection type display device or the display device. It is possible to realize a projection type display device having excellent image expressiveness and adaptability to the usage environment. Further, in the projection type display device or display device of the present invention, the voltage applied to the optical modulation means is changed based on the voltage applied to the dimming liquid crystal element, or the applied voltage period of the light modulation means is changed. In the case where the light emitted from the dimming liquid crystal element can be color-corrected by the light modulation means by changing the light, the light emitted from the dimming liquid crystal element is used as the light modulation means. Since the color tone can be corrected with, it is possible to prevent the light emitted from the light modulation means from being affected by the coloring of the light emitted from the dimming liquid crystal element, which is advantageous.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the schematic structure of the projection type liquid crystal display element of 1st Embodiment of this invention.

[Figure 2]

It is a block diagram which shows the structure of the drive circuit of the projection type liquid crystal display element.

[Fig. 3]

It is a figure for demonstrating the 1st method of determining a brightness control signal from a video signal in the projection type liquid crystal display element.

[Fig. 4]

It is a figure for demonstrating the second method.

[Fig. 5]

It is a figure for demonstrating the third method.

[Fig. 6]

It is XYZ color system chromaticity diagram which shows the example of the relationship between the voltage applied to the dimming liquid crystal element, and the white balance of the light emitted from the dimming liquid crystal element.

[Explanation of symbols]

1 Lighting device 2 light source 3 1st fly eye lens (uniform lighting means) 4 2nd fly eye lens (uniform lighting means) 5 Liquid crystal element for dimming (dimming means) 5a LCD panel 5b, 5c polarizing plate 5d polarization converter 22,23,24 Liquid crystal light bulb (light modulation means) 26 Projection lens (projection means) 30 Projection type liquid crystal display device (projection type display device) 32 DSP (1) (control signal determination means) 33 DSP (2) (dimming control means) 36 DSP (3) (optical modulation signal determination means and optical modulation control means) 39 Memories