JP3946936B2 - Optical digitizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical digitizer, and more particularly to an optical digitizer that is small in size and low in power consumption and suitable for making a small liquid crystal display device such as a PDA such as an electronic notebook or a mobile phone into a touch panel.
[0002]
[Prior art]
Recently, portable pen input computers such as PDAs are becoming popular. Many of these are equipped with a pressure-sensitive resistive film type touch panel on the liquid crystal display device, so that you can operate the menu screen and input graphics by touching or drawing with your finger or pen, Users can use it like a normal pen and notebook. However, in the pressure sensitive resistance type touch panel, since the pressure sensitive resistance film is placed on the liquid crystal display device, the display of the liquid crystal display device may become dark due to its structure. In addition, since the pen is instructed on the pressure sensitive resistance film, there is a problem that the film is broken. Furthermore, due to its structure, it has been difficult to increase the resolution. Therefore, it has been proposed to mount an optical digitizer in place of the pressure-sensitive resistive film type touch panel.
[0003]
As means for obtaining an optical signal for detecting the position of an indicator in an optical digitizer, a method of detecting a light from a light source such as a light emitting diode (LED) provided on the indicator itself, and an imaging apparatus A light emitting element such as an LED is provided in the vicinity, a retroreflective member that reflects the light from the LED is provided at the tip of the indicator, and a light source frame is provided around the coordinate reading surface and a method for detecting retroreflected light therefrom. There are three methods for detecting the direction in which light from the light source frame is blocked. For convenience, in the present specification, these methods are referred to as a light emission method, a reflection method, and a blocking method, respectively. In addition to the light source frame that directly emits light, the blocking method also includes a retroreflective frame that indirectly emits light by retroreflecting light from a light source provided near the imaging device. .
[0004]
FIG. 10 shows an example of a conventionally proposed blocking type optical digitizer. FIG. 10 is a schematic plan view of the optical digitizer. As shown in the figure, when a finger 22 serving as an indicator is placed on the coordinate reading surface 1, an image is picked up by an image pickup device 30 such as two cameras provided above the coordinate reading surface 1, and a signal from the image pickup device 30 is displayed. The image processing unit 4 performs processing to detect the designated position coordinates of the indicator 22. The imaging device 30 includes an optical system such as an imaging lens 32 and an image sensor 33. In the illustrated example, the light source frame 23 is provided on the three sides around the coordinate reading surface 1, and the imaging device 30 detects the position of the shadow where the light emitted from the light source frame 23 is blocked by the indicator 22. This is an optical digitizer with a blocking method. By detecting the direction of the shadow due to this blockage with the left and right imaging devices 30, the coordinates of the indicated position of the indicator 22 are detected by the principle of triangulation. Further, a display device 10 such as an LCD is stacked on the back surface of the coordinate reading surface 1 and functions as a touch panel. In addition, although the light source frame 23 showed what light-emits directly, it is indirectly a retroreflective frame which provides light emission sources, such as LED, in the vicinity of the imaging device 30, and retroreflects the light emitted from there. There is also an example of a light source frame that emits light. In addition, there is a type in which the pointing position coordinates are detected by imaging light from the light source by providing a dedicated pen such as an LED built-in stylus without providing a light source frame.
[0005]
In such a conventional example, because of the principle of triangulation, not only on the base line connecting the two imaging devices 30 but also in the vicinity of the base line, the coordinate detection accuracy is deteriorated (cannot be detected). It had to be defined at a position some distance from the baseline. Therefore, the part from the base line to the coordinate reading surface and the part where the imaging device and the like are mounted are invalid areas 40, and this part hinders the downsizing of the optical digitizer.
[0006]
U.S. Pat. No. 5,164,585 discloses an example of a light-emitting optical digitizer that is miniaturized by folding the optical path from the stylus 180 degrees by means of the x-axis and y-axis reflecting mirrors. In this example, the x-axis and y-axis reflecting mirrors are orthogonal to each other, and the base line connecting the two imaging devices is parallel to one of the diagonal lines of the coordinate reading surface. In this example, since a condenser lens and an image processing circuit are incorporated on the back surface of the coordinate reading surface, the structure cannot be applied to a touch panel provided with a display device on the back surface. Also, since the field window for the imaging device is on the two sides of the peripheral frame, it is impossible to provide a light source frame at that portion, so it is impossible to image light from here, and an undetectable area is created. End up. Therefore, it could not be applied to a blocking type touch panel.
[0007]
Similarly, Japanese Patent Application Laid-Open No. 10-171585 is an example of an optical digitizer that is miniaturized by folding the optical path 180 degrees by respective reflecting mirrors for the x axis and y axis. This optical digitizer can be applied to the light emission method or the blocking method, but in this example as well, a lens, a pinhole, an image sensor, and a half mirror must be arranged on the back side of the coordinate reading surface. A display device could not be provided on the back side. In addition, when applied to the blocking method, the frame around the coordinate reading surface cannot be a reflective frame that indirectly emits light using a retroreflective member, but must be a light source frame that directly emits light. The power was high. This is because a convex lens having a length approximately equal to the length of one side of the coordinate reading surface is required, and a place for arranging a light source for indirectly emitting light cannot be secured.
[0008]
[Problems to be solved by the invention]
When a very small display device such as a liquid crystal display device of a PDA or a cellular phone is made into a touch panel, the conventional optical digitizer as shown in FIG. In particular, when trying to apply to a 2-inch class liquid crystal screen such as a mobile phone, it is difficult to implement it practically because the invalid area is large.
[0009]
Further, in the examples disclosed in the above-mentioned US Pat. No. 5,164,585 and Japanese Patent Laid-Open No. 10-171585, a structural part is required on the back surface of the coordinate reading surface, so that a display device is provided behind. The touch panel could not be arranged. Furthermore, when applied to a block-type optical digitizer, the peripheral frame of the coordinate reading surface must be a light source frame that directly emits light, which hinders low power consumption.
[0010]
In view of such circumstances, the present invention reduces the ineffective area based on the principle of triangulation and a physical component mounting area such as an image sensor, and further allows a reduction in size because the degree of freedom of arrangement of the image sensor is high. It is an object of the present invention to provide an optical digitizer that can also be applied to a small liquid crystal display device used in a PDA, a mobile phone or the like.
[0011]
[Means for Solving the Problems]
In order to achieve the above-described object of the present invention, an optical digitizer of the present invention that detects the pointing position of a pointing member such as a finger or a stylus designated on a rectangular coordinate reading surface using the principle of triangulation, Two imaging means comprising an imaging lens and an image sensor, which convert optical information corresponding to the indication position of the indicator into an electrical signal, and are arranged at two locations around the coordinate reading surface, Two imaging means whose base line connecting the two imaging means is parallel to one side of the coordinate reading surface, and instructions of the indicator indicated on the coordinate reading surface by processing an output signal from the imaging means A signal processing means for calculating a position; and an optical reflecting means for turning an optical path traveling along the coordinate reading surface into a plane parallel to the coordinate reading surface by 180 degrees and entering the imaging means. To.
[0012]
The indicator may include a light source, and the imaging unit may be a light emission method that receives and forms an image of light from the light source of the indicator indicated on the coordinate reading surface and converts the light into an electrical signal. .
[0013]
The imaging means includes a light source in the vicinity thereof, and the indicator includes a retroreflective member that indirectly emits light by retroreflecting light emitted from the light source, and the imaging means includes the coordinate reading A reflection method may be employed in which retroreflected light from the indicator indicated on the surface is received and imaged and converted into an electrical signal.
[0014]
Furthermore, a light source frame that emits light directly or indirectly is provided on three sides around the coordinate reading surface, and the optical reflecting means is disposed on one side of the coordinate reading surface where the light source frame is not provided. The image pickup means may be a blocking method in which a shadow image of the indicator indicated on the coordinate reading surface is received and formed into an electric signal.
[0015]
The imaging means has a light source in the vicinity thereof, and the light source frame is made of a retroreflective member that indirectly emits light by retroreflecting light emitted from the light source.
[0016]
The optical reflecting means is arranged over the entire one side of the coordinate reading surface that is parallel to the base line and opposite to the one side where the imaging means is located.
[0017]
The coordinate reading surface may be formed of a transparent plate, and an optical path incident on the imaging unit that is folded back 180 degrees by the optical reflecting unit may be located inside the transparent plate.
[0018]
The optical reflecting means may be arranged in the vicinity of both ends of one side of the coordinate reading surface parallel to the base line and on the side where the imaging means is located.
[0019]
Further, an optical path which is disposed between the imaging lens and the image sensor and is turned 180 degrees by the optical reflecting means so that the light receiving surface of the image sensor is parallel to the coordinate reading surface is 90 degrees. You may provide the 2nd optical reflection means made into the optical path which bends and injects into the said image sensor.
[0020]
Further, an optical path which is disposed between the imaging lens and the image sensor and is turned 180 degrees by the optical reflecting means so that a light receiving surface of the image sensor is parallel to one side of the coordinate reading surface. May be further provided with a second optical reflecting means which is turned 180 degrees into a plane parallel to the coordinate reading surface and used as an optical path incident on the image sensor.
[0021]
The imaging lens may be a single lens in which the first surface that is the light incident surface is a concave surface and the second surface that is the light output surface is a convex surface.
[0022]
Further, a display device may be provided on the back surface of the coordinate reading surface. Moreover, as an attachment form, you may further have a mechanism which can be attached or detached to the existing display apparatus.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described together with illustrated examples. FIG. 1 is a light-emitting optical digitizer according to a first embodiment of the present invention, FIG. 1 (a) is a schematic plan view thereof, and FIG. 1 (b) is a schematic side view thereof. As shown, the stylus 2 as an indicator has a light source 25 such as an LED at its tip, and two imaging devices in which light from the light source 25 is arranged at two locations around the coordinate reading surface 1. The designated position coordinates of the stylus 2 are detected by imaging at 3 and processing the output signal by the image processing unit 4 using the principle of triangulation. In addition, an LCD 10 is placed on the back surface of the LCD 10 so as to overlap the coordinate reading surface 1. Normally, a protective glass 6 is provided on the surface of the LCD 10, and the surface of the protective glass 6 is used as the coordinate reading surface 1 in the present invention. Furthermore, a prism 5 is provided as an optical reflecting means over the entire side opposite to the side where the imaging device 3 is provided. As shown in FIG. 1B, the prism 5 is configured to fold the light from the LED 25 at the tip of the stylus 2 180 degrees around the protective glass 6. In this way, the optical path of light from the LED 25 at the tip of the stylus 2 that travels along the coordinate reading surface is turned 180 degrees by the prism 5 to be an optical path incident on the imaging device 3. The two imaging devices 3 are arranged so that a base line connecting the imaging devices is parallel to one side of the coordinate reading surface 1 and further arranged to receive light folded back by 180 degrees. . That is, as shown in FIG. 1B, the optical path incident on the imaging device 3 is disposed so as to pass through the back surface of the protective glass 6. By configuring in this way, there is no invalid area based on the triangulation principle in the vicinity of the base line, which has existed in the past, and it is possible to reduce the size. As shown in the figure, the image pickup apparatus 3 includes a diaphragm 31, an imaging lens 32, and an image sensor 33. However, the present invention is not limited to this, and various conventional image pickup apparatuses can be used. is there. The prism 5 is not limited to this, and various prisms can be used as long as the optical path can be folded back by 180 degrees. For example, it may be configured to be folded back 180 degrees using two mirrors. Furthermore, in the illustrated example, an optical path incident on the imaging device 3 passes between the protective glass 6 and the LCD 10, but the present invention is not limited to this. For example, the optical path is once bent at 90 degrees using a single mirror, Further, of course, it may be configured such that an optical path incident on the imaging device 3 passes through the back surface of the LCD 10 by bending another 90 degrees using another mirror. By doing so, it is possible to eliminate the invalid area of the portion where the imaging device is mounted. Such a configuration is particularly effective when there is a limit on the arrangement area of the optical digitizer, but there is not much limitation on the thickness.
[0024]
Next, FIG. 2 shows a second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same parts. FIG. 2 is a block-type optical digitizer, FIG. 2 (a) is a schematic plan view thereof, and FIG. 2 (b) is a schematic side view thereof. As shown in the figure, retroreflective frames 20 are provided on three sides other than the one side on which the prism 5 of the coordinate reading surface 1 is provided. Further, an LED 34 is provided in the vicinity of the imaging device 3, and light from the LED 34 passes between the LCD 10 and the protective glass 6 and is folded back 180 degrees by the prism 5, and travels along the coordinate reading surface 1. , Enters the retroreflective frame 20. The light incident on the retroreflective frame 20 is retroreflected so as to return to the incident direction, is again folded 180 degrees by the prism 5, and is imaged on the image sensor 33 in the imaging device 3 by the imaging lens 32. When the finger 22 is placed on the coordinate reading surface 1, the image pickup apparatus 3 can pick up an image of the shadow, thereby calculating the designated position coordinates of the finger 22. By configuring in this way, the same effect as in the first embodiment described above can be obtained. That is, since the invalid area based on the principle of triangulation near the base line can be reduced, the size can be reduced. In addition, since a retroreflective frame can be used, it is possible to reduce power consumption compared to a light emitting frame that directly emits light. However, the present invention is not limited to this, and it is of course possible to use a light emitting frame that directly emits light. In addition, the retroreflective frame includes a glass bead and the like, but various frames can be used as long as a retroreflective effect can be obtained, such as a corner cube array. Furthermore, the imaging device 3 includes a diaphragm 31, an imaging lens 32, and an image sensor 33. Various conventional imaging devices can be used. However, in order to save space, in the illustrated example, As the imaging lens 32, a plano-convex lens or the like is sliced parallel to the optical axis of the lens and is further cut into a V shape in a fan shape. This is the lens structure disclosed in Japanese Patent Application No. 2000-101831 by the present applicant, and detailed description thereof is omitted. Also, the structure of the prism 5 is not limited to the illustrated example, and can be variously modified as in the first embodiment.
[0025]
Next, FIG. 3 shows a third embodiment of the present invention. In the figure, the same reference numerals as those in the other figures represent the same thing. FIG. 3 is a block diagram type optical digitizer, FIG. 3 (a) is a schematic plan view thereof, and FIG. 3 (b) is a schematic side view thereof. In the present embodiment, protective glass, prisms, and retroreflective frames are integrally formed of a transparent acrylic material for the purpose of further reducing the number of components. As shown in the figure, the prism surface 50 is integrally molded on one side of the protective glass, and the corner cube array surface 21 is integrally molded on the remaining three sides. The light emitted from the LED 34 passes through the inside of the transparent plate on which the coordinate reading surface 1 is formed, and is folded back 180 degrees on the prism surface 50. The folded light travels along the coordinate reading surface 1 and enters the corner cube array surface 21. Since the corner cube array surface 21 has retroreflective characteristics, the incident light is retroreflected so as to return to the incident direction, is again folded by the prism surface 50 by 180 degrees, and is incident on the imaging device 3. ing. When the indicator such as the finger 22 blocks the optical path on the coordinate reading surface 1, the direction of the shadow can be detected by the imaging device 3, so that the indicated position coordinates of the indicator can be obtained. With such a configuration, the number of parts can be reduced, so that it can be easily manufactured. When a 2-inch class liquid crystal display device such as a cellular phone is made into a touch panel, it is particularly effective in such a case because an inexpensive one is desired. In the illustrated example, the peripheral frame is a corner cube array surface for ease of integral molding, but the present invention is not limited to this, and various surfaces can be used as long as they have retroreflective properties.
[0026]
Next, FIG. 4 shows a fourth embodiment of the present invention. In the figure, the same reference numerals as those in the other figures represent the same thing. 4A and 4B are block-type optical digitizers, FIG. 4A is a schematic plan view thereof, and FIG. 4B is a schematic side view thereof. The difference from the first to third embodiments described so far is that the optical reflecting means 51 for turning the optical path 180 degrees is not arranged over the entire side of the coordinate reading surface, but shown in the drawing. In this way, the coordinate reading surface 1 is disposed in the vicinity of both ends of one side. The imaging device 3 is disposed in the vicinity of the optical reflecting means 51. The light emitted from the LED 34 is folded back 180 degrees by the optical reflecting means 51 (mirrors 51a and 51b in the illustrated example), travels along the coordinate reading surface 1, is retroreflected by the retroreflective frame 20, and returns. The image is again folded 180 degrees by the optical reflecting means 51 and imaged on the image sensor 33 by the imaging lens 32. When the finger 22 is pointed on the coordinate reading surface 1, the pointed position can be detected by capturing an image of the shadow as in the above-described embodiment. With this configuration, since the imaging device is mounted on the back surface of the invalid area based on the principle of triangulation, it becomes possible to reduce the invalid area based on the physical component mounting area such as an image sensor. The digitizer can be downsized. In the illustrated example, a combination of two mirrors is shown for the optical reflecting means. However, the present invention is not limited to this, and a prism or the like can be used as long as it can be turned 180 degrees. Various members can be used.
[0027]
Next, FIG. 5 shows a fifth embodiment of the present invention. In the figure, the same reference numerals as those in the other figures represent the same thing. FIG. 5 shows a block-type optical digitizer whose basic configuration is the same as that of the optical digitizer shown in FIG. 4, but the feature of this illustrated example is that it is 180 by a mirror 51 as shown in FIG. The second reflection means 52 is provided to bend the optical path folded back by 90 degrees between the imaging lens 32 and the image sensor 33. The optical path traveling along the coordinate reading surface is folded by 180 degrees by the mirror 51, passes through the imaging lens 32, is bent by 90 degrees by the second mirror 52, and becomes an optical path incident on the image sensor 33. With this configuration, the light receiving surface of the image sensor 33 can be made parallel to the coordinate reading surface 1, so that the desired size can be obtained without being limited by the physical size of the image sensor 33. A mounting layout can be obtained. It should be noted that the angle at which the second mirror 52 is bent is not limited to 90 degrees, and can of course be variously changed in accordance with the mounting position of the image sensor 33.
[0028]
By the way, in the embodiments so far, as shown in FIG. 6A, as the imaging lens, the light incident surface is a flat surface, the light exit surface is a convex surface, the light entrance surface is narrow and the light exit surface is wide. The fan-shaped lens cut in a V-shape is shown in the figure, because this is a lens effective for realizing a wide-angle lens with a single lens. However, in this lens structure, since the focal length (back focus) is short, it may be physically impossible to dispose a mirror between the imaging lens and the image sensor. In this case, as shown in FIG. 6B, the back focus can be extended by processing the light incident surface into a concave surface. With such a configuration, a mirror or the like can be disposed between the imaging lens and the image sensor.
[0029]
FIG. 7 shows a sixth embodiment of the present invention. In the figure, the same reference numerals as those in the other figures represent the same thing. 7A and 7B are block-type optical digitizers, FIG. 7A is a schematic partial plan view thereof, and FIG. 7B is a schematic side view thereof. In the present embodiment, as shown in FIG. 7, the second reflecting means 53 is provided for bending the optical path folded back 180 degrees by the mirror 51 between the imaging lens 32 and the image sensor 33 by 180 degrees. . The optical path that travels along the coordinate reading surface is folded back 180 degrees by the mirror 51, passes through the imaging lens 32, is further folded 180 degrees by the second mirror 53, and becomes an optical path that enters the image sensor 33. Here, if the mirror 51 is arranged at an angle of 45 degrees with respect to one side of the coordinate reading surface 1, the second reflecting means 53 is 1 of the coordinate reading surface 1 as shown in FIG. Arranged at an angle of 22.5 degrees to the side. That is, the second reflecting means 53 reflects at an angle of 45 degrees with respect to an axis orthogonal to the axis in the direction of folding back 180 degrees. By doing so, the light receiving surface of the image sensor 33 can be made parallel to one side of the coordinate reading surface 1. With such a configuration, it is possible to achieve a desired mounting layout without being restricted by the physical size of the image sensor, so that the imaging apparatus can be assembled in a compact manner.
[0030]
Next, FIG. 8 shows a seventh embodiment of the present invention. In this embodiment, the present invention is applied to a portable optical digitizer. FIG. 8A is a perspective view thereof, FIG. 8B is a schematic plan view thereof, and FIG. 8C is a schematic side view thereof. In the figure, the same reference numerals as those in the other figures represent the same thing. This optical digitizer is a light-emitting type digitizer that is used on a desk or the like. As shown in the figure, the optical digitizer of this embodiment formed with a rectangular parallelepiped housing is placed on the desk like a paperweight, and the indication position indicated by the stylus etc. with the light source provided on the indicator itself is detected on the front side It can be done. It is also possible to use a reflection type optical digitizer in which an LED is provided in the vicinity of the imaging lens 32 and a retroreflective member or the like is provided at the tip of the indicator to detect reflected light therefrom. Conventionally, the casing is enlarged by the amount of the invalid area, or the coordinates cannot be read in the vicinity of the apparatus. However, in the optical digitizer of this embodiment, the invalid area is folded, so that the depth is very small. A short rod-like compact optical digitizer can be realized. In the examples disclosed in US Pat. No. 5,164,585 and JP-A-10-171585 described in the conventional example, two 180 degree folding mirrors are required for each of the x coordinate and the y coordinate. Therefore, at least two sides of the coordinate reading surface must be enclosed, and the size of the apparatus cannot be increased. However, according to this embodiment, only one side of the coordinate reading surface is used. Since the device can be placed, a compact device can be realized. In the illustrated example, the image sensors 33 are arranged on the left and right, respectively. However, using another mirror or the like, for example, one image sensor is provided near the center of the apparatus, and it can be shared by the left and right imaging lenses. Of course it is possible.
[0031]
Next, FIG. 9 shows an eighth embodiment of the present invention. The present embodiment is an optical digitizer intended to be attached to an existing display device to form a touch panel, and FIG. 9A is a side view of the state attached to the display device, and FIG. Is a partially enlarged view of the optical digitizer. The illustrated example is a block-type optical digitizer, and a retroreflective frame 20 is provided on three sides around the coordinate reading surface. The imaging device 3 is provided in the vicinity of both ends of one side of the coordinate reading surface where the retroreflective frame 20 is not provided. The coordinate reading surface is defined by the protective glass 6. The optical digitizer of the present embodiment further includes an attaching / detaching mechanism 12 that can be attached to and detached from an existing display device 11, for example, a cathode ray tube display device or a liquid crystal display device, and has an attachment form. As shown in FIG. 9B, the imaging device 3 includes an LED 34 that is a light source, and light from the LED 34 travels along a coordinate reading surface on the display screen. The light retroreflected and returned by the retroreflective frame 20 is folded 180 degrees by a mirror 51 or the like as an optical reflecting means, and the light passing through the imaging lens 32 is bent 90 degrees by the second reflecting means 52. And enters the image sensor 33. These configurations are the same as the embodiments described so far, and the configuration of the attachment form is not limited to the illustrated examples, and the various embodiments described above can be applied. The protective glass 6 may be a simple transparent glass, but an optical digitizer integrated with a monitor filter can be realized by using an antireflection filter or the like.
[0032]
Note that the optical digitizer of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. For example, the light emission method, the reflection method, and the blocking method can be changed, and the effect of the present invention can be obtained by any method. In addition, the imaging lens may of course be constituted by a conventionally well-known optical system. Further, the optical reflection means that turns back 180 degrees is not limited to a prism, and various types of mirror reflection means can be used as long as they can turn back 180 degrees.
[0033]
【The invention's effect】
As described above, according to the optical digitizer of the present invention, the ineffective area can be reduced, so that the size can be reduced, and the present invention can also be applied to a small liquid crystal display device used for a PDA, a mobile phone, or the like. An excellent effect can be achieved. In addition, since the apparatus can be miniaturized, it can be applied to a portable optical digitizer and can be easily formed in an attachment form.
[Brief description of the drawings]
FIG. 1 is an optical digitizer according to a first embodiment of the present invention, FIG. 1 (a) is a schematic plan view thereof, and FIG. 1 (b) is a schematic side view thereof.
FIG. 2 is an optical digitizer according to a second embodiment of the present invention, FIG. 2 (a) is a schematic plan view thereof, and FIG. 2 (b) is a schematic side view thereof.
3 is an optical digitizer according to a third embodiment of the present invention, FIG. 3 (a) is a schematic plan view thereof, and FIG. 3 (b) is a schematic side view thereof.
4 is an optical digitizer according to a fourth embodiment of the present invention, FIG. 4 (a) is a schematic plan view thereof, and FIG. 4 (b) is a schematic side view thereof.
FIG. 5 is an optical digitizer according to a fifth embodiment of the present invention.
6A and 6B show the structure of an imaging lens. FIG. 6A shows a planar light incident surface, and FIG. 6B shows a concave light incident surface. .
7 is an optical digitizer according to a sixth embodiment of the present invention, FIG. 7 (a) is a schematic partial plan view thereof, and FIG. 7 (b) is a schematic side view thereof.
8 is an optical digitizer according to a seventh embodiment of the present invention, FIG. 8 (a) is a perspective view thereof, FIG. 8 (b) is a schematic plan view thereof, and FIG. ) Is a schematic side view thereof.
FIG. 9 is an optical digitizer according to an eighth embodiment of the present invention, FIG. 9 (a) is a side view of the optical digitizer mounted on a display device, and FIG. 9 (b) is a diagram of the optical digitizer. FIG.
FIG. 10 is an example of a conventional optical digitizer.
[Explanation of symbols]
1 Coordinate reading surface
2 Stylus
3 Imaging device
4 Image processing section
5 Prism
6 Protective glass
11 Display device
12 Detachment mechanism
20 retroreflective frames
21 Corner cube array surface
22 fingers
23 Light source frame
25 Light source
30 Imaging device
32 Imaging lens
33 Image sensor
40 Invalid area
50 Prism surface
51 mirror
52 Second mirror
53 Second mirror

Claims (6)

An optical digitizer for detecting the indicated position of a pointing object such as a finger or stylus indicated on a rectangular coordinate reading surface using the principle of triangulation, the optical digitizer,
Two imaging means comprising an imaging lens and an image sensor, which converts optical information corresponding to the indication position of the indicator into an electrical signal and is arranged at two locations around the coordinate reading surface, Two imaging means in which a base line connecting two imaging means is parallel to one side of the coordinate reading surface;
Signal processing means for calculating an indicated position of the indicator indicated on the coordinate reading surface by processing an output signal from the imaging means;
Arranged only on one side of the coordinate reading surface that is parallel to the base line and opposite the one side where the imaging means is located, and proceeds along the first surface along the coordinate reading surface Optical reflecting means for bending the light into a plurality of directions so as to be an optical path that travels along a parallel second surface spaced from the first surface by a predetermined distance. When,
An optical digitizer comprising:   2. The optical digitizer according to claim 1, wherein the coordinate reading surface is formed of a transparent plate, and an optical path incident on the imaging unit folded by the optical reflecting unit is located in the transparent plate. An optical digitizer characterized by An optical digitizer for detecting the indicated position of a pointing object such as a finger or stylus indicated on a rectangular coordinate reading surface using the principle of triangulation, the optical digitizer,
Two imaging means comprising an imaging lens and an image sensor, which converts optical information corresponding to the indication position of the indicator into an electrical signal and is arranged at two locations around the coordinate reading surface, Two imaging means in which a base line connecting two imaging means is parallel to one side of the coordinate reading surface;
Signal processing means for calculating an indicated position of the indicator indicated on the coordinate reading surface by processing an output signal from the imaging means;
An optical path of light that travels along the first surface along the coordinate reading surface, arranged in front of each imaging means, in the vicinity of both ends of one side on the side where the imaging means is located, which is parallel to the base line, An optical reflecting means for bending the light a plurality of times so as to be an optical path that travels along a parallel second surface spaced from the first surface by a predetermined distance ;
An optical digitizer characterized in that an invalid area based on the principle of triangulation on the back side of the coordinate reading surface is used as a mounting area of the imaging means .   4. The optical digitizer according to claim 3, wherein the optical digitizer is further disposed between the imaging lens and the image sensor so that a light receiving surface of the image sensor is parallel to the coordinate reading surface. An optical digitizer, comprising: a second optical reflecting means that bends the optical path folded by the reflecting means by 90 degrees to form an optical path incident on the image sensor.   4. The optical digitizer according to claim 3, further disposed between the imaging lens and the image sensor so that a light receiving surface of the image sensor is parallel to one side of the coordinate reading surface. And an optical digitizer comprising: a second optical reflecting means that further turns the optical path folded by the optical reflecting means back to a third surface parallel to the coordinate reading surface to be incident on the image sensor. .   6. The optical digitizer according to claim 3, wherein the imaging unit and the optical reflecting unit are mounted in a paperweight rectangular housing.

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