Compact optical pointing apparatus and method

Description of the invention

The invention relates to a movable display and pointing device, in particular an optical pointing device.

A known pointing device such as a mouse enables the user to point to a location on the screen for interactively positioning a cursor or selecting a location on an imaging surface, such as a display screen or other such surface. Pointing devices are used in desktop computers, mobile devices, handheld computers, mobile phones, personal digital assistants, internet devices, and more. The indication on the display may be textual, for example highlighted text, or graphic, for example a cursor.

User interfaces in portable electronic consumer devices are becoming increasingly complex, which typically requires multiple controls that must be manipulated by the user. However, the consumer usually requires devices that are small and compact. Introducing a sufficient number of controls and keeping the device dimensions small enough is difficult to implement for acceptance by the recipient. Moreover, there is a practical limitation in the placement of small controls such as buttons in relation to each other for the operation of the fingers of the average user.

Two main types of pointing devices in portable electronic consumer devices are known, namely one-dimensional and two-dimensional. One-dimensional pointing devices include, for example, toggle switches, knobs, sliders, multi-position toggle switches, and rocker switches. Pointing devices are used to select movement in one direction on a user interface, for example a graphical user interface. Movement in one direction is usually interpreted as up / down, forward / backward and next / previous depending on the device.

One-dimensional indicating devices such as knobs are designed to occupy a very small, strictly limited area of ​​the surface of the utility device. For example, the edge of the knob protrudes through a slotted opening in the housing of the device and allows the user to rotate the knob in both directions by pulling the finger along the edge of the knob tangentially to its circumference. However, slotted openings in the housing allow contaminants to enter the interior of the device.

Rocker and rocker switches are usually larger than knobs and require a sufficiently large surface area to receive the user's finger tip. In some cases rocker switches are implemented as two adjacent buttons connected by a common stick. Such devices are designed, for example, so that the device housing is sealed from the outside. However, these devices have moving parts and can occupy larger surface areas of the device compared to the other one-dimensional devices mentioned previously.

Two-dimensional pointing devices include, for example, touchpads, trackballs, mice, and joysticks. Pointing devices are typically used to select traffic in two directions simultaneously on the user interface. Any two-dimensional pointing device can also be used as a one-dimensional pointing device by trivially ignoring one of the dimensions supported by the device. Two-dimensional pointing devices are more versatile than one-dimensional pointing devices and are typically used to select and manipulate information on a two-dimensional display by indicating the X, Y position that is associated with a given function via a graphical user interface. Another two-dimensional indicating device is used to control two independent features of the device, such as pitch versus timbre, aileron deflection angle versus rudder angle, and interest rate versus timing.

Touch manipulators are flat surface areas that sense the absolute point where the user's finger tip touches that area. The minimum dimensions of the touch manipulator must therefore be slightly larger than the user's finger tip for the device to be effective, and the practical dimensions are several times larger. Touch manipulators usually require a very shallow depth in the device housing in relation to the surface area they require and are sealed against the surroundings. However, due to the size of the surface area required by touch manipulators, they are not widely used in smaller devices such as handheld devices.

PL 208 403 B1

Ball manipulators use ball rolling to provide a relative motion indication output to the user interface. The user touches the ball and makes it roll. The rolling angle of the ball is tested to determine the two-dimensional indication information. The minimum diameter of the ball manipulator is limited, for example, by the size of the sensor device used to determine the rotation. Ball manipulators require the same order depth inside the housing as the diameter of the manipulator ball. However, many portable electronic consumer devices do not have a depth sufficient to accommodate the trackball pointing device and associated sensing mechanisms. In addition, the ball manipulator is not sealed to the environment, and therefore allows contaminants to enter the interior of the device.

Joysticks are not typically used in portable electronic consumer devices largely because they need to protrude above the surface of the device and typically require considerable volume or depth in the device to accommodate the sensing mechanisms. A joystick in the form of a push button or mushroom head is usually implemented as a two-dimensional rocker switch. Typically, a push button and mushroom head manipulator cannot indicate speed or distance, only direction.

The most common pointing device is a mouse, which essentially functions like an inverted trackball. Rather than directly touching the ball and rolling it, the user moves the entire housing containing the inverted trackball over an auxiliary flat surface, a mouse pad, separate from the housing. This auxiliary flat surface has minimum dimensions determined by the dimensions of the mouse body, and in practice the minimum dimensions of the mouse pad are much larger than the user's hand. During operation, the friction between the ball and the mouse pad causes the ball to rotate inside the housing, and the further operation is similar to that of a trackball. In addition to the demands made by the trackball, the known mouse requires a flat support surface and the sensing of movement is performed at the bottom of the housing.

Another known embodiment of the mouse requires the use of a fine, regularly repeating optical pattern or mesh printed on the surface of the mouse pad over which the user moves the optical mouse. An optical mouse of this type uses sensors on the bottom surface of the housing that are positioned with a predetermined grid scale on the surface of the mouse pad and thus sense the relative movement of the known grating underneath and use this information to sense direction and speed. The additional mesh surface makes it necessary to use the mouse pad itself, which is hard to facilitate cleaning and prevent damage, the mouse pad is usually several times larger than the user's hand, and the user has to try to maintain the orientation of the optical mouse in accordance with the orientation of the mesh. on the mouse pad.

There is a known intelligent optical mouse that uses optical sensors and image processing techniques to determine relative motion. As with other known mouse embodiments, it requires an auxiliary surface on which the mouse operates. This device differs from the previously described optical mesh mouse in that it does not require a separate reticle repeating pad and uses multiple sensing areas and an image processor to determine the speed and direction of movement of the flat, smooth surface beneath it. The sensor regions are thus located on the bottom surface of the optical mouse. The flat sensor window on the bottom of the mouse receives light for optical sensor areas. When operating, a flat area such as the desktop of a desk is needed for the operation of the mouse. The minimum dimensions of the flat area are at least as large as the body of the mouse, i.e. approximately the dimensions of the user's hand, and in practice the required flat area is several times larger than the user's hand.

It is known from U.S. Patent 5,463,725 a movable device comprising a surface texture sensor circuit element, the surface texture detection circuit operatively connected to the surface texture sensor circuit is used to determine the direction of movement and / or the speed of movement of the texture and to produce the outputs. display indication data.

Also known from US Patent No. 5,966,122 is an apparatus comprising a CCD region, a memory for storing at least one image, and a surface texture sensor circuit element and a multiple displaced image display.

PL 208 403 B1

Apparatus for MPEG coding along with correlation and block traffic evaluation are also known, for example in US Pat. Nos. 5,608,656, US Pat. No. 5,157,732, US Pat. No. 5,247,586 and US Pat. No. 5,461,423.

According to the invention, in the movable display and indicating device, the sensor window is part of a surface texture sensor circuit, and the push button with the sensor window is one of the plurality of keyboard keys in the moving device, and a surface texture motion sensor circuit for determining the direction of movement is operatively linked to the surface texture sensor circuit. and the speed of movement of the surface texture, represented by the surface texture image signals, at the sensor window regardless of the pressure of the button being pressed, the surface texture motion sensor circuit having an output output connected to the display via a user interface and a second output connected to memory.

Preferably, the surface texture sensor circuit comprises a sensing region of at least one of a plurality of charge-coupled devices and a plurality of thermal sensors.

Preferably, the surface texture sensor circuit comprises a light source for illuminating a surface texture to detect a surface texture.

Preferably, the surface texture sensor circuit includes a focusing lens operably coupled to charge-coupled devices to detect surface texture.

Preferably, the surface texture sensor circuit comprises a visible light filter disposed between the surface texture and the charge-coupled devices.

Preferably, a surface texture sensor circuit is connected to memory for storing one or more images, the surface texture motion sensor circuit is attached to the surface texture sensor circuit to produce a surface texture motion image represented by the image data by comparing the image with one or more previously. memorized images.

Preferably, the button to be pressed has a sensor window disposed thereon having the same height as the top surface of the button.

It is an advantage of the invention to provide a display and indicating device with a simple structure, without any moving parts, which facilitates its manufacture, operation, maintenance and repair. The device of the invention is less susceptible to false triggering by objects moving relative to it, due to the requirement of close proximity in the focal area and the requirement to process ridges and furrows in the skin texture.

The subject of the invention is presented in the drawing examples, in which:

Fig. 1 is a block diagram of a display and indicating device according to the invention, Fig. 2 is a flowchart for a method of providing indication information to a display according to the invention, Fig. 3 is a flow chart in more detail for determining the direction of movement and / or speed of movement of a surface texture such as like fingerprints or other surface textures according to the invention, fig. 4 - a diagram of a mobile device comprising the display and indication device according to the invention, fig. 5 - a block diagram of a surface texture sensor according to the invention, fig. 6 - a cross-section of a button having a surface texture sensor circuit according to the invention embedded therein, and fig. 7 - a data structure diagram representing frames for iterating samples according to the method of Fig. 3.

Fig. 1 shows an embodiment of a display and indicating device 10 provided in an apparatus comprising a display 12, a user interface 14, and a memory 16. The display and indicating device 10 comprises a surface texture sensor circuit 18, e.g., a fingerprint reading optical circuit, and a sensor circuit 20. motion surface texture. The memory 16 is part of the surface texture sensor circuit and / or the surface texture motion sensor circuit. By fingerprints herein is meant any part of the texture of the leather or other texture and not the entire fingerprint. The surface texture sensor circuit 18 is for detecting at least a portion of a fingerprint or other skin pattern or other surface, such as a glove placed near the surface texture sensor circuit 18 circuit.

The surface texture sensor circuit 18 outputs image signals 22 representing one or more images of the detected skin texture to the circuit of the surface texture motion sensor 20. The surface texture sensor circuit 18 includes an optical sensor that includes, for example, regions of CCD charge-coupled devices, thermal sensors, a reflection system associated with a light source such as a light emitter, or, for example, a rectangular array of temperature sensors. The surface texture sensor circuit 18 includes a light transmitter, such as a conventional light emitting diode, to illuminate the texture of the skin at the fingertip or other part of the skin to facilitate examination of the skin texture, the light emitting diodes used emitting light at different wavelengths, e.g. infrared.

Light emitting diode illumination differs from that obtained from coherent laser-based interferometry such as optical translation measurement in many respects, including that the light source of the invention need not be a coherent light source and the invention does not require a grating close to the surface. In the case where a sensor based on an active light emitter is used, an active visible and / or infrared light emitter is used to locally illuminate the user's finger tip. The light output from the transmitter can be very small because of the small surface area that is illuminated and because the user's finger is brought closer to the sensor window.

Surface texture sensor circuit 18 processes data received from optical sensors to produce a fingerprint image, such as part of a fingerprint or other skin texture image, which image shows, for example, the ridges and grooves of a user's finger tip, or other surface texture as some kind of optical pattern. . The surface texture motion sensor circuit 20 uses ridges and furrows in the skin texture as an optical pattern to sense the movement and speed of movement of the skin texture as the finger is passed over the sensor window.

The circuit of the surface texture motion sensor 20 is a microcontroller, discrete logic, microprocessor, state machine, or a combination of hardware, software, or firmware. The surface texture motion sensor circuit 20 is operatively connected to the surface texture sensor circuit 18 to receive one or more skin texture image signals 22 and determine at least one direction of motion and / or speed of motion of the skin texture examined by the surface texture sensor circuit 18. Preferably, both the direction of movement and the speed of movement are determined. The circuit of the surface texture motion sensor 20 produces an indication output 24 for the display 12. The indication output 24 represents a position on the display as indicated by the end of a user's finger as used by the user interface 14, such as a graphical user interface or other interface that provides a visual indication of the position on the display 12. The user interface 14 provides, for example, the position signal of a displayed cursor 26. on the display 12. The indication output 24 is any data representing the visual cue of the position on the display, for example, it is highlighted or selected text.

The memory 16 is part of the device or is part of the circuit of the surface texture motion sensor 20 or the circuit of the surface texture sensor 18. Part of the surface texture sensor circuit 18 may be used in the surface texture motion sensor circuit 20, and vice versa. The surface texture motion sensor circuit 20 stores in memory 16 an image received from the surface texture sensor circuit 18. The speed and direction of movement of the surface texture are then determined by comparing the captured image with one or more previously captured images received from the surface texture sensor circuit 18.

Fig. 2 is a flowchart for a method of providing display hint information, such as the method performed by the display and indicating device 10 of Fig. 1. The method starts at block 200 by examining a surface texture by a surface texture sensor mechanism. At block 202, the direction of movement and / or the speed of movement of the surface texture is determined as it is moved along a sensor window associated with the display and indicating device 10. At block 204, an indication output for the display is generated based on the specified direction of movement and / or speed. motion surface texture. Returning to block 200, the surface texture study includes in this example processing the received optical data from a surface texture sensor, such as a plurality of areas of charge-coupled devices, a thermal sensor array, or a light sensor, as well as generating data representing an image of the surface texture being tested.

Fig. 3 is a flowchart for a method for determining the direction of movement and / or speed of movement of a fingerprint according to the invention, and data structures representing frames for a particular sampling iteration of the flowchart of Fig. 3 are shown in Fig. 7. In block 300, an image is recorded, namely, one or more images received from a surface texture sensor, such as a fingerprint sensor. At block 302, the received image 710 is compared to one or more previously inspected fingerprint images 760. In block 304, the question is answered,

Image movement has occurred. When no motion has occurred, the received image 710 is substantially in line with the captured image 700. When the two images are substantially in agreement, it is said to have high correlation. A way to describe this agreement is to calculate a correlation score, with a higher score the better correlation. Once motion has occurred, block 306 determines the direction of motion.

Each image 710 received from the surface texture sensor circuit 18 is, for example, a set of pixels received over a given period of time, and may be considered an information frame. The finger motion sensor circuit 20 implements motion detection algorithms, such as generating motion vectors for part of an image or the whole image, such as in moving image encoding and compression in MPEG, or other motion detection techniques.

Returning to Figures 3 and 7, where motion has occurred, the received image 710 and the recorded image 700 have significant differences, and the motion detection algorithm is used to determine the direction and amount of motion. The recorded image 700 is subjected to at least one of the following image transformations: shifting, rotating, and scaling to produce a plurality of acceptable images 715, 720, 725, 730, 735, 740, 745, 750, which are stored in memory 760. In Fig. 7 admissible image 715 is shifted up and to the left of the captured image 700, admissible image 720 is upward-shifted relative to the captured image 700, permissible image 725 is shifted up and to the right of the captured image 700, permissible image 730 is shifted to the left of the captured image 700. of the recorded image 700, permissible image 735 is shifted to the right of the recorded image 700, admissible image 740 is shifted downward and to the left of the captured image 700, permissible image 745 is shifted downward with respect to the captured image 700, and admissible image 750 is shifted down and to the right of the captured image 700. The permissible images 715, 720, 725, 730, 735, 740, 745, 750 are then compared to the received image 710 and if they are substantially in agreement, then the image transformation used to produce the tolerable image represents movement of the skin texture. If the acceptable image does not match, then another transformation attempt or set of transforms is performed, for example, to shift the captured image or transformed image significantly to the left or shift to the right. The first shift attempt is selected using a history of last predetermined directions and quantities or other means such as MPEG displacement block vectors.

By repeatedly attempting to compare or correlate the received image 710 with different permissible image transformations 715, 720, 725, 730, 735, 740, 745, 750, it is possible to obtain one of two results. The first result is that optionally a portion of the transformed permissible image 735 is substantially in line with the corresponding portion of the received image 710, in which case the movement of the skin texture is determined based on an offset applied to the stored image 700, resulting in the permissible image 735, thereby block 204 is generated indicating the output. The second result is that no allowable transformation has sufficient correlation with the received image to intentionally identify the motion. The latter result usually means that the movement of the skin texture was so great that it could not be accurately measured, for example a completely different part of the skin texture with different ridges and furrows is represented in the received image compared to the recorded image. In this second result, the invention uses a history of previous direction and speed determinations to determine whether there was a probability of significant displacement. If the history shows an accurate compliant direction and increasing displacement, the invention restores the previous directions and the speed of movement corresponding to the maximum speed of movement that would otherwise be detectable, thereby creating a speed-limiting function for large displacements of skin texture. If the history does not show consistent direction and increasing displacement, then direction and speed are provided consistent with the still texture of the skin.

In another embodiment, the received image is subjected to at least one of the image transformations: shift, rotation, and scaling, such as shifting the image to the left a small interval, to produce an acceptable image that can be saved. The acceptable image is then compared to the captured image, and if they are substantially in agreement, then the image transformation used to produce the acceptable image represents the inverse of the skin texture motion. If the acceptable image is not matched, then another transformation is attempted, for example shifting the received image or processed image to the left by a larger interval or to the right. The transformation is performed in this embodiment on the received image, not the captured image, and the comparison is performed between the acceptable transformable received images and the recorded image, rather than a comparison between the allowed transformed captured image and the received image, while the resulting direction is the inverse of the transformation applied to the received image.

The invention requires the use of at least one recorded image and one received image to enable comparison between two images, and during the comparison only one of these images needs to be saved. In a preferred embodiment, multiple images from previous iterations of the algorithm are saved to potentially reduce the average computational load per iteration. In another embodiment, the received image is processed into a plurality of permissible images in parallel, or the received image is processed into a plurality of permissible images in a series array.

In another embodiment, the motion detection algorithm is used on one or more subsets of a received image and one or more subsets of the recorded image in analogy to the MPEG traffic block method. In order to support the use of components in MPEG standard, subsets are selected as blocks and macroblocks associated with block motion vector algorithms in MPEG standard. Alternatively, the subsets represent specific recognizable features of the fingerprint, such as helical fingerprints, joints, parallel ridges and furrows, scars, or other distinguishing features. The total movement of the subsets can be averaged to determine the direction and amount of skin texture movement. Alternatively, such an average is used as the initial allowable transform when performing full image correlation as described above.

Returning to block 304, if no motion has occurred, the method continues to record the pictures and analyze the incoming pictures to determine if motion has occurred. For example, the operation shown at blocks 202 and 204 is performed with the circuit of the surface texture motion sensor 20, for example.

In an embodiment, each recorded image and received image have a time stamp associated with it as a measure of the elapsed time since the reference time. Examples of normal time stamps include dates, time of the day, a counter value produced according to the system clock or frequency standard, and an elapsed time counter. The time difference is calculated by subtracting the time stamp value associated with the recorded image from the time stamp value of the received image. The direction and amount of movement of the skin texture is determined as previously described by comparing the received image with one or more stored images. The amount of skin texture movement divided by the time difference is the speed of the skin texture movement. The speed of movement and the direction of movement together provide complete information about the motion vector related to the texture of the skin.

In another embodiment, the elapsed time counter is started after each direction and speed determination and is stopped and checked at the beginning of each direction and speed determination, thus giving the time difference directly without requiring a subtraction step.

Figure 4 shows a mobile device 400 such as, without limitation, a cellular telephone, personal digital assistant, internet device, wristwatch, telephone, personal information organizer, or other mobile device. Mobile device 400 in the form of a cellular telephone has a display 12 on which graphical images 402 are displayed and a cursor 404 controlled by the indication output 24. The mobile device 400 has a housing 406 with a display 12 that is operatively connected to the housing 406 and is a flip-flop display or other display. Mobile device 400 includes a radiotelephone subsystem 408 that includes a plurality of activation buttons 412 to facilitate cellular telephone communication. The buttons 412 form a block of keys to be pressed, virtual keys represented as graphic images 402, or other buttons. Mobile device 400 also includes the display and indicating device 10 with the surface texture sensor window 410 as part of the perimeter of the surface texture sensor 18. The surface texture motion sensor circuit 20 is a programmable processor or processors in the mobile device 400 or some other structure. The surface texture sensor window 410 is disposed on a surface that is not the bottom surface of the housing 406. In FIG. 4 The surface texture sensor window 410 is located on the top surface of the mobile device 400, but may also be located on a side surface or other surface as required by the design of the mobile device 400. Since the display and indicating device 10 of the present invention does not require the use of a spacer outer or lower surface 8

In this case, the surface texture sensor window 410 is not located on the bottom surface. The surface texture sensor window 410 is relatively small as it only needs to detect a small portion of the fingerprint's movement. The fingerprint sensor window 410 is so small that it includes only a few rows of ridges and furrows in the texture of the skin. Due to the fact that the texture of the skin varies from one user to another, practically the smallest surface is in the order of 2.5 mm x 2.5 mm (6.25 mm²). In a preferred embodiment, the surface texture sensor window 410 has an area of ​​the order of 20 mm² and approximately the shape of a square. The surface texture sensor window 410 need not be rectangular in shape and may include discrete areas of any contour. The sensing regions are located outside or within the surface texture sensing window 410. Rows of sensor areas are positioned sufficiently close to each other to detect the spatial representation of the at least one light energy reflected from the finger and / or the infrared energy emitted from the finger, depending on the type of surface texture sensor circuit used. The sensing area may be designed to use a very small surface area of ​​the mobile device. Typically, it is not necessary to examine or process an image of a large area of ​​the user's finger tip. For example, the sensor window 410 is a surface that allows energy to pass through it, and is preferably sealed to prevent physical contaminants from entering the device housing.

Fig. 5 shows a block diagram of a surface texture sensor circuit 18 using a sensor area based on areas of the CCD charge-coupled devices. The circuit of the fingerprint motion sensor 20 is a controller or other control logic that receives image signals 22 from the area of ​​charge-coupled devices 500. The focusing lens 502, the top of which serves as a sensor window 410 or a portion thereof, focuses light on the region of the charge-coupled devices 500. Preferably, the focusing lens 502 is constructed such that the visible light energy or infrared radiation energy at a height of approximately 5 mm from the top surface of the sensing window is focused on the area of ​​the charge-coupled devices 500, but light from beyond 5 mm from the top surface is dissipated. Direct contact with the sensor window is not necessary. A visible light filter 504, such as a visible light filtering film, is placed between the focusing lens 502 and the area of ​​the charge-coupled devices 500 to filter out visible light and transmit infrared radiation energy to the area of ​​the charge-coupled devices 500. Visible light filter 504 serves as an optical filter that is capable of filtering out visible light so that it does not strike the area of ​​the charge-coupled devices 500. Image signals 22 are analog or digital depending on the complexity of the area of ​​the charge coupled devices 500.

Fig. 6 shows a cross-sectional view of an embedded display and indicating device. The key or button 600 houses the circuit of the fingerprint sensor 18, and thus the sensor window 410. An opening 602 is provided in the button 600 to guide the wires 604 or connectors needed to connect the circuit board to the circuit board or interface. The control button, typically used as an "enter" key or other key, may also house the periphery of the fingerprint sensor 18, thereby minimizing the area of ​​the fingerprint to be picked up by the display and pointing device. The sensor window is also placed on the button or key. The user positions the cursor or text on the graphical user interface using the display and pointing device, and may use the button itself to select and activate an action associated with the mobile device.

In operation, the display and indicating device examines, by means of a surface texture sensor circuit, for example, surface parts such as a finger or skin texture, and by means of a surface texture motion detection circuit, determines the direction of movement and the speed of movement of the texture of the tested skin to produce an output for display. These outputs are, for example, data representing a visual indication of a position on the display screen, such as the position of a cursor or highlighted text, or other position. The method of providing cue information to the display includes sensing a surface texture, determining the direction of movement and speed of movement of the surface texture, and generating an indication output for the display based on the determined direction of movement and the speed of movement of the surface texture being tested. In an exemplary embodiment, the method includes processing data received from a surface texture sensor circuit to produce a first image, storing the first image, and comparing

The first image with one or more previously recorded images to determine if surface texture movement has occurred, and if so, the speed and direction of movement are determined.

In another embodiment, a mobile device such as a handheld, portable or other device includes a surface texture sensor circuit with a small surface area, called a sensor window, that detects skin texture images such as ridges and furrows at the user's finger tip, which is used as some type of optical image for sensing movement through a sensor window. It is not necessary for the optical pattern of the user's finger tip to be uniform. In one example, multiple regions of the CCD charge-coupled devices are used in conjunction with a visible light filter for infrared radiation to pass to regions of the charge-coupled devices. In addition, if desired, a focusing lens or other focusing mechanism is used as the sensor window that focuses the infrared energy present above the sensing window, for example at a distance of 0.7mm or another, such that the user's finger tip, skin texture, or other surface does not need to be in contact with the sensor surface to be detected. The charge-coupled device areas are designed as a sensor system. There are also thermal sensor systems that react to invisible radiation, so that the use of a filter is not necessary.

In one embodiment, the surface texture sensor circuitry is embedded in a push button in the device such that the button is used as both a surface area housing the sensor window and a pressable surface area to actuate the button upon user activation. The sensor window is positioned within a button or other control surface, or between keys or buttons, and in any area separate from the buttons or control buttons. The sensor window is located on a surface that is not the bottom surface of the mobile device, such as the side surface or the top surface. The small surface area used makes it easier to control the cursor or other user interface mechanism. The use of infrared waves allows dirt to pass through a deposit or layer that potentially hampers the operation of purely optical sensors, such as sensors that employ techniques to emit visible laser radiation.

The use of the display and pointing device according to the invention is extended from a mobile device to stationary devices such as printers, copiers, facsimile machines, desktops, navigation units or other devices.