JP2012133631A - Optical position detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical position detection device that can accurately detect the position of a target object, in even a system using the light intensity distribution of detection light formed by a light guide plate.SOLUTION: In an optical position detection device 10, light incident parts 13e to 13h are provided at corner parts 13a to 13d of a light guide plate 13, respectively, and reflection parts 13r for reflecting detection light L2 transmitting in the light guide plate 13 toward a light emission surface 13s are provided in the light guide plate 13. Thereby, the detection light L2 made incident from the light incident parts 13e to 13h is deflected toward the light emission surface 13s by the reflection parts 13r in the middle of advancing while transmitting in the light guide plate 13, and the light intensity distribution of the detection light L2 is formed on the light emission surface 13s side. In the light guide plate 13, the reflection parts 13r are provided with the distribution that increases density as the reflection parts 13r are away from the corner parts 13a to 13d.

Description

  The present invention relates to an optical position detection device that optically detects the position of a target object.

  As an optical position detection device that optically detects a target object, for example, as shown in FIG. 10A, detection light is directed toward the target object from each of a plurality of light sources for detection 12 through a light guide plate 13. Has been proposed in which the detection light reflected by the target object is detected by a photodetector. (For example, refer to Patent Document 1).

  Here, the light guide plate 13 is provided with a light incident portion into which the detection light emitted from the light source for detection 12 is incident at each of the plurality of corner portions, and a light emitting surface or a back surface facing the light emitting surface. The reflective portions such as the unevenness and the printing layer are uniformly formed. For this reason, the detection light incident from the light incident portion travels while propagating through the light guide plate 13, is deflected toward the light emission surface by the reflection portion, and is emitted from the light emission surface. As a result, a light intensity distribution of the detection light is formed on the light exit surface side of the light guide plate 13. Further, the detection intensity of the detection light by the photodetector corresponds to the light intensity at the location where the target object is located. Therefore, the position of the target object can be detected based on the detection intensity of the detection light at the photodetector.

  For example, when detecting the X coordinate, as indicated by a solid line in FIG. 10A, the two detection light sources 12 located on one side X1 in the X axis direction are turned on, while the other X2 in the X axis direction is turned on. The two detection light sources 12 that are positioned are turned off to form a light intensity distribution in which the intensity decreases linearly from one side X1 in the X-axis direction toward the other side X2. Next, as shown by a solid line in FIG. 10B, the two detection light sources 12 located on the other side X2 in the X axis direction are turned on, while the two detection light sources located on the one side X1 in the X axis direction are turned on. The light source 12 is turned off to form a light intensity distribution in which the intensity decreases linearly from the other side X2 in the X-axis direction toward the one side X1. Therefore, the detection intensity of the detection light in the photodetector during the period in which the light intensity distribution shown in FIG. 10A is formed, and the photodetector in the period in which the light intensity distribution shown in FIG. 10B is formed. X-coordinate (X-coordinate data) of the target object can be detected by comparing the detected intensity of the detected light. Similarly, the light intensity distribution in which the intensity decreases linearly from one side Y1 in the Y-axis direction toward the other side Y2, and the intensity decreases linearly from the other side Y2 in the Y-axis direction toward the one side Y1. If the light intensity distribution is formed and the same detection is performed, the Y coordinate (Y coordinate data) of the target object can be detected.

JP 2010-204994 A

  However, as in the optical position detection device described in Patent Document 1, in order to use the light intensity distribution, the light exit surface or the reflective portion such as the printed layer is uniformly formed on the back surface facing the light exit surface. When the light guide plate is used, the strength at the corner increases, while the strength sharply decreases with distance from the corner. Therefore, the actually formed light intensity distribution is shown in FIG. ) And (b), as indicated by the alternate long and short dash line, since the intensity does not change linearly, it is difficult to accurately detect the position of the target object.

  In view of the above problems, an object of the present invention is an optical position detection that can accurately detect the position of a target object even if the light intensity distribution of detection light formed by a light guide plate is used. To provide an apparatus.

  In order to solve the above problems, the present invention is an optical position detection device that optically detects the position of a target object, and includes a plurality of detection light sources that emit detection light and the detection light sources. A rectangular light guide plate having an outer peripheral side surface provided with a light incident part on each of a plurality of corners, a light emitting surface intersecting the outer peripheral side surface, and the detection light from the light emitting surface A light detector that detects the detection light reflected by the target object located in the emission space, and a detection intensity of the detection light at the light detector when the plurality of detection light sources are sequentially turned on. A position detection unit that detects the position of the target object, and the light guide plate includes a reflection unit that reflects the detection light propagating through the light guide plate toward the light exit surface. Provided with a distribution that increases in density as it moves away from It is characterized in that is.

  In the present invention, the light incident part is provided at the corner of the light guide plate, and the light guide plate is provided with a reflection part for directing detection light propagating through the light guide plate toward the light exit surface. For this reason, the detection light incident from the light incident part is deflected toward the light emission surface by the reflection part while traveling through the light guide plate and is emitted from the light emission surface. As a result, a light intensity distribution of the detection light is formed on the light exit surface side with respect to the light guide plate. Further, the detection intensity of the detection light by the photodetector corresponds to the light intensity at the location where the target object is located. Therefore, the position of the target object can be detected based on the detection intensity of the detection light at the photodetector. Here, since the light incident part is provided at the corner of the light guide plate, the emission intensity from the light exit surface is high at the corner and tends to rapidly decrease as the distance from the corner increases. In the invention, the light guide plate is provided with a distribution in which the density increases as the reflecting portion is separated from the corner portion. For this reason, in the position spaced apart from a corner | angular part, the emission efficiency from a light-projection surface is high. Therefore, in the direction along the light emitting surface, it is possible to properly form a light intensity distribution in which the intensity decreases linearly from one side to the other side, and the intensity is linear from the other side to the one side. Therefore, the light intensity distribution that decreases can be appropriately formed. Therefore, the position of the target object can be accurately detected using the light intensity distribution of the detection light formed by the light guide plate.

  In the present invention, the position detector turns on a part of the light sources for detection arranged at two corners adjacent to each other in the circumferential direction among the plurality of light sources for detection, The detection intensity of the detection light at the photodetector when the other detection light sources arranged are turned off, and the part of the detection light sources are turned off, while the other detection light sources are turned on. It is preferable to detect the position of the target object based on the detection intensity of the detection light at the photo detector. According to such a configuration, compared to the case where the light sources for detection are turned on one by one, the intensity of the detection light is large, and a light intensity distribution in which the intensity varies linearly over a wide range is formed. Can do.

  In this invention, in the said light-guide plate, the density of the said reflection part is reducing toward the edge part from the intersection of the two virtual lines which connected the corner parts located diagonally among these corners. It is preferable. In the vicinity of the side part of the light guide plate, the intensity of the detection light emitted from the light source for detection provided at the corner part sandwiching the side part is synthesized. Therefore, if the density of the reflection part is decreased from the intersection of two imaginary lines connecting the corners located diagonally toward the side part, the intensity changes linearly in the direction along the light exit surface. The light intensity distribution can be formed appropriately.

  In the present invention, in the light guide plate, the degree of increase in the density of the reflection portion from the corner portion toward the intersection is determined between the reflection portion and the side portion from the corner portion. The density is preferably smaller than the degree of increase in density. In the vicinity of the side part of the light guide plate, the intensity of the detection light emitted from the light source for detection provided at the corner part sandwiching the side part is synthesized. Accordingly, if the degree of increase in the density of the reflection part from the corner toward the intersection is smaller than the degree of increase in the density of the reflection part from the corner to the intersection and the side, A light intensity distribution in which the intensity changes linearly in the direction along the light exit surface can be appropriately formed.

  In the present invention, the light guide plate is set to an intersection of two virtual lines that connect diagonal corners among the plurality of corners, and an emission space of the detection light from the light exit surface. Alternatively, a configuration may be adopted in which the intersection of two imaginary lines connecting the corners located diagonally in the detection target space is shifted. According to the present invention, since an appropriate intensity distribution can be formed by the distribution of the reflection portion, the center of the light guide plate (the intersection of two imaginary lines connecting corner portions located diagonally) and detection Even when the center of the target space (the intersection of two imaginary lines connecting corners located diagonally) is deviated, an appropriate light intensity distribution can be formed in the entire detection target space.

  In the present invention, the reflection portion is formed on the back surface of the light guide plate facing the light emitting surface, and is formed on the back surface facing the light emitting surface of the light guide plate. The structure which is a dot-like printing layer or particles dispersed in the light guide plate can be employed.

  In the present invention, the detection light is preferably infrared light. According to such a configuration, since the detection light is not visually recognized, even when the detection target space is set at a position overlapping the display surface of the display device, the detection light does not hinder visual recognition of the image. Further, even when the detection target space is set at a position overlapping with the display surface of the display device, the wavelengths of the detection light and the display light are different, so that the reflection portion provided on the light guide plate does not hinder the display of the image.

It is explanatory drawing which shows the principal part etc. of the apparatus with a position detection function to which this invention is applied. It is explanatory drawing of the detection light used with the optical position detection apparatus to which this invention is applied. It is explanatory drawing which shows the structure of the reflection part provided in the light-guide plate of the optical position detection apparatus to which this invention is applied. It is explanatory drawing which shows distribution of the reflection part provided in the light-guide plate of the optical position detection apparatus to which this invention is applied. It is explanatory drawing of the light intensity distribution formed when the light source for a detection is lighted one by one in the optical position detection apparatus to which this invention is applied. It is explanatory drawing which shows a mode that the light source for a detection is lighted sequentially with a predetermined pattern in the optical position detection apparatus to which this invention is applied, and light intensity distribution is formed. It is explanatory drawing which shows a mode that the light intensity distribution for coordinate detection is formed with the detection light radiate | emitted from the light source for a detection in the optical position detection apparatus to which this invention is applied. It is explanatory drawing which shows typically the position detection principle in the optical position detection apparatus to which this invention is applied. It is explanatory drawing of another apparatus with a position detection function to which this invention is applied. It is explanatory drawing of the conventional optical position detection apparatus.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the axes that intersect each other in the direction along the viewing surface on which information such as the display surface of the display device is displayed are defined as the X axis and the Y axis, and the axes that intersect the X axis and the Y axis are the Z axis. Will be described. Therefore, the Z-axis direction is a direction that intersects the viewing surface. In the drawings referred to below, one side in the X-axis direction is the X1 side, the other side is the X2 side, one side in the Y-axis direction is the Y1 side, the other side is the Y2 side, The direction (one side) away from the viewing surface (display surface) is shown as the Z1 side, and the other side is shown as the Z2 side. In the drawings referred to in the following description, the scales of the respective members are different from each other in order to make each member large enough to be recognized on the drawings.

[Configuration of equipment with position detection function]
(Overall configuration of equipment with position detection function)
FIG. 1 is an explanatory diagram showing a main part of a device with a position detection function to which the present invention is applied, and FIGS. 1A and 1B are used for an optical position detection device in a device with a position detection function. It is explanatory drawing which shows the layout etc. of an optical component, and explanatory drawing which shows the electrical structure of an optical position detection apparatus. FIG. 2 is an explanatory diagram of the detection light used in the optical position detection device to which the present invention is applied. FIGS. 2A, 2B, and 2C show the light reflected by the target object as a photodetector. Is an explanatory diagram showing the state of being received by a plane, an explanatory diagram showing a sectional view of the light reflected by the target object being received by the photodetector, and an explanation showing the attenuation state of the detected light in the light guide plate FIG.

  As shown in FIGS. 1 (a), 2 (a), and 2 (b), the apparatus 100 with a position detection function of the present embodiment is a display device including a direct-view electro-optical device such as an organic electroluminescence device or a plasma display device. 8 (viewing surface constituent member) and an optical position detection device 10 for optically detecting the position of the target object Ob located on the viewing surface 80 (display surface) side of the display device 8.

  The optical position detection device 10 uses a space that overlaps the viewing surface 80 on one side Z1 in the Z-axis direction as a detection target space 10R (an emission space of the detection light L2), and a plurality of detection light beams that emit the detection light L2. Among the light source 12 (detection light sources 12A to 12D) and the detection light L2 emitted from the detection light source 12, a photodetector that detects a part of the detection light L3 reflected by the target object Ob in the detection target space 10R. 30.

  In the present embodiment, four detection light sources 12 </ b> A to 12 </ b> D are used as the plurality of detection light sources 12. Each of the plurality of light sources for detection 12 is configured by an LED (light emitting diode) or the like, and emits detection light L2 made of infrared light as diverging light. That is, since the detection light L2 preferably has a wavelength region that is efficiently reflected by the target object Ob such as a finger, the detection light L2 has a peak in the infrared region where the reflectance on the surface of the human body is high. For example, the detection light L2 is near infrared light close to the visible light region, for example, light having a peak near the wavelength of 850 nm.

  Further, the optical position detection device 10 of this embodiment includes a light guide plate 13 made of a transparent resin plate such as polycarbonate or acrylic resin, and the detection light L2 emitted from the light source for detection 12 is the light guide plate 13. The detection target space 10 </ b> R is configured by a space that is emitted to one side Z <b> 1 in the Z-axis direction and through which the detection light L <b> 2 is emitted. Here, the light guide plate 13 is disposed so as to overlap the display device 8 on one side Z1 in the Z-axis direction. For this reason, the image generated by the display device 8 is displayed on the light exit surface 13 s of the light guide plate 13. Therefore, in this embodiment, the light emission surface 13 s of the light guide plate 13 is used as a substantial display surface of the display device 8.

  In this embodiment, the light guide plate 13 has a substantially rectangular planar shape, and the surface of the light guide plate 13 facing the detection target space 10R is the light emission surface 13s, and the outer periphery intersecting the light emission surface 13s. In the side surface 13m, four detection light sources 12 (detection light sources 12A to 12D) face the light emitting surfaces at the four corner portions 13a to 13d. Accordingly, the corner portions 13a to 13d of the light guide plate 13 are used as light incident portions 13e to 13h on which the detection light L2 emitted from the detection light source 12 is incident. In this embodiment, the light incident portions 13e to 13h are formed by chamfering the corner portions 13a to 13d. Further, the four light sources for detection 12 have their center optical axes directed to corners located diagonally in the light guide plate 13. More specifically, the detection light source 12A arranged at the corner 13a has the central optical axis directed to the diagonal corner 13b, and the detection light source 12B arranged at the corner 13b is a diagonal corner. The central optical axis is directed to 13a. Similarly, the detection light source 12C arranged at the corner 13c has the central optical axis directed to the diagonal corner 13d, and the detection light source 12D arranged at the corner 13d is centered at the diagonal corner 13c. The optical axis is pointing.

  Further, as will be described later, a reflective portion made of fine irregularities or the like is provided on the back surface 13t of the light guide plate 13, and such a reflective portion is incident from the corner portions 13a to 13d and propagates inside. The detection light L2 is gradually deflected as it travels in the propagation direction, and is emitted from the light exit surface 13s toward one side Z1 in the Z-axis direction. For example, the detection light L2a emitted from the detection light source 12A is emitted from the light emission surface 13s while traveling in the direction indicated by the arrow A inside the light guide plate 13. The detection light L2b emitted from the detection light source 12B is emitted from the light emission surface 13s while traveling in the direction opposite to the direction indicated by the arrow A inside the light guide plate 13. The detection light L2c emitted from the detection light source 12C is emitted from the light emission surface 13s while traveling in the direction indicated by the arrow C inside the light guide plate 13. The detection light L2d emitted from the detection light source 12D is emitted from the light emission surface 13s while traveling in the direction opposite to the direction indicated by the arrow C inside the light guide plate 13.

  In the optical position detection device 10 having such a configuration, for example, the light amount of the detection light L2a emitted from the light guide plate 13 to the detection target space 10R is from the detection light source 12A as shown by a solid line in FIG. Decreases with distance. Further, the amount of the detection light L2b emitted from the light guide plate 13 to the detection target space 10R attenuates with the distance from the detection light source 12B, as indicated by a dotted line in FIG. Similarly, the detection lights L2c and L2d emitted from the other detection light sources 12C and 12D are emitted from the light emission surface 13s while being attenuated. Therefore, the detection light L2 forms a light intensity distribution, which will be described later with reference to FIGS. 4 and 6, etc., in the detection target space 10R.

  An optical sheet such as a prism sheet or a light scattering plate may be disposed on the light exit side of the light guide plate 13 as necessary in order to make the detection lights L2a to L2d uniform. In this embodiment, infrared light is used as the detection light L2, and the wavelength is different from the light (visible light) used for displaying an image in the display device 8. For this reason, even if the back surface 13t of the light guide plate 13 or the light emitting surface 13s is provided with a reflection portion such as irregularities with respect to infrared light, there is no significant problem in image display.

(Configuration of the photodetector 30)
The photodetector 30 includes a light receiving element such as a photodiode or a phototransistor, and the photodetector is directed to the detection target space 10R at a substantially central position of a side portion of the light guide plate 13 outside the detection target space 10R. . In the present embodiment, the photodetector 30 is composed of a photodiode or the like having a sensitivity region at a position substantially overlapping with the center peak of the detection light L2.

(Configuration of the light source for reference 12R)
Furthermore, the optical position detection device 10 of the present embodiment includes a reference light source 12R that causes the reference light Lr to enter the photodetector 30 without passing through the detection target space 10R, and the reference light source 12R is detected. Like the light source 12, the LED emits near infrared light close to the visible light region, for example, light having a peak near the wavelength of 850 nm as divergent light. When such a reference light source 12R is used, when the initial conditions of the detection light sources 12A to 12D and the photodetector 30 are set, the detection of the reference light Lr emitted from the reference light source 12R by the photodetector 30 is performed. It can be based on strength. Further, when detecting the X coordinate, the Y coordinate, and the Z coordinate of the target object Ob by a method to be described later, the detection intensity of the reference light Lr by the photodetector 30 and the photodetector of the detection light L3 reflected by the target object Ob. The result of comparison with the detected intensity at 30 can be used.

(Electrical configuration of the optical position detection device 10)
As shown in FIG. 1B, the optical position detection device 10 detects from a light source driving unit 14 that drives a detection light source 12 (detection light sources 12 </ b> A to 12 </ b> D) and a reference light source 12 </ b> R, and a photodetector 30. The light source drive unit 14 and the position detection unit 50 are configured in a common semiconductor integrated circuit 500, for example. The light source driver 14 detects the light source 12 (detection light sources 12A to 12D) and the light source drive circuit 140 (light source drive circuits 140a to 140d, 140r) for driving the reference light source 12R and the light source drive circuit 140. And a light source control unit 145 that controls lighting of the reference light source 12R (detection light sources 12A to 12D) and the reference light source 12R.

  The position detection unit 50 includes a signal processing unit 55 and a coordinate detection unit 56. The coordinate detection unit 56 detects the position (coordinate data) of the target object Ob based on the detection result of the photodetector 30. . In this embodiment, the coordinate detection unit 56 includes an X coordinate detection unit 51, a Y coordinate detection unit 52, and a Z coordinate detection unit 53. The light source control unit 145 and the position detection unit 50 are connected by a signal line, and the driving of the detection light source 12 and the detection operation of the position detection unit 50 are performed in conjunction with each other. The position detection unit 50 is electrically connected to the display device 8 and can switch an image displayed on the display device 8 according to the position or movement of the target object Ob. Further, information can be input based on the positional relationship between the position and movement of the target object Ob and the image displayed on the display device 8.

(Configuration of the reflective portion of the light guide plate 13)
FIG. 3 is an explanatory diagram showing the configuration of the reflecting portion provided on the light guide plate 13 of the optical position detection device 10 to which the present invention is applied, and FIGS. 3 (a), 3 (b), 3 (c) and 3 (d). These are explanatory drawing of the reflective part which consists of a round hole-shaped recessed part, explanatory drawing of the reflective part which consists of prism-shaped recessed parts, explanatory drawing of the reflective part which consists of printed layers, and explanatory drawing of the reflective part which consists of scattering particles. FIG. 4 is an explanatory view showing the distribution of the reflecting portions provided on the light guide plate 13 of the optical position detecting device 10 to which the present invention is applied. FIGS. 4 (a), 4 (b), and 4 (c) are the reflecting portions. 5 is an explanatory diagram showing the distribution of the three-dimensionally, an explanatory diagram showing the distribution of the reflecting portion in shades, and an explanatory diagram showing the density of the reflecting portion in the direction indicated by arrows R1 and R2 in FIG.

  As shown in FIG. 3, in the light guide plate 13 used in the optical position detection device 10 of the present embodiment, a reflective portion 13 r is provided on the back surface 13 t of the light guide plate 13. Among the reflecting portions 13r, the reflecting portion 13r shown in FIG. 3A is formed of a round hole-shaped recess provided on the back surface 13t of the light guide plate 13, and the detection light L2 propagating through the light guide plate 13 is reflected. The light hits the wall surface of the portion 13r, is reflected, and is deflected toward the light emitting surface 13s. The reflecting portion 13r shown in FIG. 3 (b) is formed of a prism-shaped recess provided on the back surface 13t of the light guide plate 13, and the detection light L2 propagating through the light guide plate 13 strikes the inclined surface of the reflecting portion 13r and is reflected. It is deflected toward the exit surface 13s. The reflective portion 13r shown in FIG. 3C is composed of a dot-like print layer provided on the back surface 13t of the light guide plate 13, and the detection light L2 propagating through the light guide plate 13 strikes the reflective portion 13r and is reflected. It is deflected toward the exit surface 13s. In this embodiment, the printing layer is made of ink or other material that efficiently reflects infrared light, such as white or yellow. In addition, when the reflection part 13r is comprised by a printing layer, in addition to controlling distribution by the dot density of a printing layer, the density of the reflection part 13r is made into predetermined distribution using multiple printing layers from which the reflection efficiency with respect to infrared light differs. It is good. The reflection part 13r shown in FIG. 3D is made of fine particles, and the detection light L2 propagating through the light guide plate 13 is reflected by the reflection part 13r and deflected toward the light emission surface 13s.

  In this embodiment, as shown in FIG. 4, the reflection portion 13 r is provided with a distribution in which the density increases as the distance from the corner portions 13 a to 13 d increases. More specifically, as shown in FIGS. 4A and 4B, in the light guide plate 13, two imaginary lines connecting the corners located diagonally among the plurality of corners 13 a to 13 d. When the intersection point is the center O13, the reflecting portion 13r is the highest at the center O13, and the density decreases monotonously toward the peripheral portion. Therefore, the density of the reflecting portion 13r monotonously decreases from the center O13 toward the corner portions 13a to 13d. Further, the density of the reflecting portion 13r monotonously decreases from the center O13 toward the side portion 13n.

  Here, as indicated by an arrow R1 in FIG. 4B, the degree to which the density of the reflecting portion 13r increases from the corners 13a to 13d toward the center O13 is indicated by a solid line R1 in FIG. 4C. As shown by an arrow R2 in FIG. 4B, the degree to which the density of the reflecting portion 13r increases from the corner portions 13a to 13d between the center O13 and the side portion 13n is shown in FIG. It is represented as indicated by a solid line R2 in FIG. As can be seen by comparing the density changes indicated by solid lines R1 and R2 in FIG. 4C, the degree to which the density of the reflecting portion 13r increases from the corner portions 13a to 13d toward the center O13 is determined from the corner portions 13a to 13c. It is smaller than the degree of increase in the density of the reflecting portion 13r from 13d toward the center O13 and the side portion 13n.

  For this reason, in this embodiment, as described below with reference to FIGS. 5 and 7, a light intensity distribution in which the intensity of the detection light L2 linearly changes can be formed in the detection target space 10R.

(Explanation of light intensity distribution)
FIG. 5 is an explanatory diagram of the light intensity distribution formed when the detection light sources 12 (detection light sources 12A to 12D) are turned on one by one in the optical position detection device 10 to which the present invention is applied. FIG. 6 shows a state in which a light intensity distribution is formed by sequentially turning on the detection light sources 12 (detection light sources 12A to 12D) in a predetermined pattern in the optical position detection device 10 to which the present invention is applied. It is explanatory drawing. FIG. 7 is an explanatory diagram showing a state in which a light intensity distribution for coordinate detection is formed by the detection light L2 emitted from the detection light source 12 in the optical position detection device 10 to which the present invention is applied. In FIG. 6, the detection light source 12 that is lit is represented in gray.

  In FIG. 1A, FIG. 2A, and FIG. 5, in the optical position detection device 10 of the present embodiment, when the detection light source 12A is turned on, the other detection light sources 12B to 12D are turned off. In the detection target space 10R, a light intensity distribution having peaks at the corners on one side X1 in the X-axis direction and one side Y1 in the Y-axis direction is formed (see FIG. 5A). The intensity varies linearly. When the detection light source 12B is turned on and the other detection light sources 12A, 12C, and 12D are turned off, the detection target space 10R has the other side X2 in the X-axis direction and the other side Y2 in the Y-axis direction. A light intensity distribution having a peak at the corner is formed (see FIG. 5B), and the intensity varies linearly in the light intensity distribution. Further, when the detection light source 12C is turned on while the other detection light sources 12A, 12B, and 12D are turned off, the other side X2 in the X-axis direction and the one side Y1 in the Y-axis direction are placed in the detection target space 10R. A light intensity distribution having a peak at the corner is formed (see FIG. 5C), and the intensity changes linearly in the light intensity distribution. In addition, when the detection light source 12D is turned on and the other detection light sources 12A to 12C are turned off, the detection target space 10R has corners on one side X1 in the X-axis direction and the other side Y2 in the Y-axis direction. A light intensity distribution having a peak at the portion is formed (see FIG. 5D), and in this light intensity distribution, the intensity changes linearly.

  Accordingly, as shown in FIG. 6, among the plurality of detection light sources 12, a part of the detection light sources 12 arranged at two corners adjacent to each other in the circumferential direction in the light guide plate 13 are turned on, while the light guide plate 13. 7 is turned off, the light intensity distribution described with reference to FIG. 7 can be formed. According to the light intensity distribution, one light source for detection can be formed. A light intensity distribution having a higher intensity than that when the lamp 12 is turned on can be formed. More specifically, as shown in FIG. 6A, when the detection light sources 12A and 12D are in the on state and the other detection light sources 12B and 12C are in the off state, as shown in FIG. Thus, the first light intensity distribution L2Xa for X coordinate detection (first light intensity distribution for first coordinate detection) in which the intensity of the detected light monotonously decreases from one side X1 in the X-axis direction toward the other side X2 is formed. The In this embodiment, in the first light intensity distribution L2Xa for X coordinate detection, the intensity of the detection light L2 linearly decreases from one side X1 in the X-axis direction to the other side X2, and detection is performed in the Y-axis direction. The intensity of the light L2 is constant.

  On the other hand, as shown in FIG. 6B, when the detection light sources 12B and 12C are turned on and the other detection light sources 12A and 12D are turned off, as shown in FIG. In addition, an X coordinate detection second light intensity distribution L2Xb (first coordinate detection second light intensity distribution) in which the intensity of the detection light monotonously decreases from the other side X2 in the X-axis direction toward the one side X1 is formed. . In this embodiment, in the X-coordinate detection second light intensity distribution L2Xb, the intensity of the detection light L2 linearly decreases from the other side X2 in the X-axis direction toward the one side X1, and in the Y-axis direction, the detection is performed. The intensity of the light L2 is constant.

  Here, the light guide plate 13 and the detection target space 10R are both rectangular when viewed from the Z-axis direction, and the centers of both coincide with each other. Therefore, if the light intensity distribution is formed symmetrically in the X-axis direction with reference to the light guide plate 13, the light intensity distribution can be formed symmetrically in the X-axis direction even in the detection target space 10R.

  Further, as shown in FIG. 6C, when the detection light sources 12A and 12C are in the on state and the other detection light sources 12B and 12D are in the off state, as shown in FIG. A first light intensity distribution L2Ya for Y coordinate detection (second light intensity distribution for second coordinate detection) in which the intensity of the detection light monotonously decreases from one side Y1 in the axial direction toward the other side Y2 is formed. In the present embodiment, in the first light intensity distribution L2Ya for Y-coordinate detection, the intensity of the detection light L2 decreases linearly from one side Y1 in the Y-axis direction to the other side Y2, and in the X-axis direction, detection is performed. The intensity of the light L2 is constant.

  On the other hand, as shown in FIG. 6D, when the detection light sources 12B and 12D are turned on and the other detection light sources 12A and 12C are turned off, as shown in FIG. In addition, a second light intensity distribution L2Yb for Y coordinate detection (second light intensity distribution for second coordinate detection) in which the intensity of the detected light monotonously decreases from the other side Y2 in the Y-axis direction toward the one side Y1 is formed. . In this embodiment, in the second light intensity distribution L2Yb for Y-coordinate detection, the intensity of the detection light L2 linearly decreases from the other side Y2 in the Y-axis direction toward the one side Y1, and in the X-axis direction, the detection is performed. The intensity of the light L2 is constant.

  Here, the light guide plate 13 and the detection target space 10R are both rectangular when viewed from the Z-axis direction, and the centers of both coincide with each other. Therefore, if the light intensity distribution is formed symmetrically in the Y-axis direction with reference to the light guide plate 13, the light intensity distribution can be formed symmetrically in the Y-axis direction even in the detection target space 10R.

  Although illustration is omitted, when all the four detection light sources 12 (detection light sources 12A to 12D) are turned on, the intensity decreases from the light guide plate 13 toward the one side Z1 from the other side Z2 in the Z-axis direction. A light intensity distribution for coordinate detection is formed. In such a Z coordinate detection light intensity distribution, the intensity monotonously decreases in the Z-axis direction, and such a change can be regarded as a substantially linear change in a limited space, ie, the detection target space 10R. In the Z coordinate detection light intensity distribution, the intensity is constant in the X-axis direction and the Y-axis direction.

(Basic principle of X coordinate detection)
FIGS. 8A and 8B are explanatory views schematically showing the position detection principle in the optical position detection apparatus 10 to which the present invention is applied. FIGS. 8A and 8B show the detection light reflected by the target object Ob. It is explanatory drawing which shows intensity | strength, and explanatory drawing which shows a mode that the light intensity distribution of detection light is adjusted so that the intensity | strength of the detection light reflected by the target object Ob may become equal.

  In the optical position detection device 10 of this embodiment, the detection light source 12 is turned on to form a light intensity distribution of the detection light L2 in the detection target space 10R, and the detection light L2 reflected by the target object Ob is detected by the photodetector. The position detection unit 50 detects the position of the target object Ob in the detection target space 10 </ b> R based on the detection result of the light detector 30. Thus, the principle of coordinate detection will be described with reference to FIG. Note that, for example, a microprocessor unit (MPU) is used as the light source control unit 145 or the position detection unit 50 when acquiring the position information of the target object Ob in the detection target space 10R based on the detection result of the photodetector 30. Thus, it is possible to employ a configuration in which processing is performed by executing predetermined software (operation program). In addition, a configuration using hardware such as a logic circuit may be employed.

  In the optical position detection apparatus 10 of the present embodiment, the X-coordinate detection first light intensity distribution L2Xa and the X-coordinate detection second light intensity distribution L2Xb described with reference to FIGS. 7A and 7B are used. Thus, the position in the X-axis direction is detected. At that time, the detection light sources 12A and 12D and the detection light sources 12B and 12C are driven in opposite phases. More specifically, in the first period for X coordinate detection, the light sources for detection 12A and 12D are turned on, while the light sources for detection 12B and 12C are turned off, and the first light for X coordinate detection shown in FIG. An intensity distribution L2Xa is formed. Next, while the detection light sources 12A and 12D are turned off, the detection light sources 12B and 12C are turned on to form the X coordinate detection second light intensity distribution L2Xb shown in FIG. 7B. Therefore, when the target object Ob is arranged in the detection target space 10R, the detection light L2 is reflected by the target object Ob, and a part of the reflected light is detected by the photodetector 30. Here, the first light intensity distribution L2Xa for X coordinate detection and the second light intensity distribution L2Xb for X coordinate detection have a constant distribution. Therefore, the X coordinate detection unit 51 compares the detection intensity at the photodetector 30 in the first period for X coordinate detection with the detection intensity at the photodetector 30 in the second period for X coordinate detection. The X coordinate of the target object Ob can be detected by the method described below with reference to FIG.

  First, as shown in FIG. 8A, in the first period for X coordinate detection and the second period for X coordinate detection, the first light intensity distribution L2Xa for X coordinate detection and the second light intensity distribution L2Xb for X coordinate detection are set. Sequentially formed so that the absolute values are equal and opposite in the X-axis direction. In this state, if the detection value LXa at the photodetector 30 in the first period for X coordinate detection is equal to the detection value LXb at the photodetector 30 in the second period for X coordinate detection, the target object Ob is X It can be seen that it is located in the axial center.

  On the other hand, when the detection value LXa at the photodetector 30 in the first period for X coordinate detection is different from the detection value LXb at the photodetector 30 in the second period for X coordinate detection, detection is performed. The control amount (driving current) for the light source for detection 12 is adjusted so that the values LXa and LXb are equal, and as shown in FIG. 8B, again for X coordinate detection in the first period for X coordinate detection. A first light intensity distribution L2Xa is formed, and an X coordinate detection second light intensity distribution L2Xb is sequentially formed in the second X coordinate detection period. Then, the detection value LXa at the photodetector 30 in the first period for X coordinate detection is made equal to the detection value LXb at the photodetector 30 in the second period for X coordinate detection. The X coordinate of the target object Ob is determined by the ratio or difference between the control amount (current value) for the detection light sources 12A and 12D and the control amount (current value) for the detection light sources 12A and 12D when the differential is performed. Can be detected. Further, the ratio or difference between the adjustment amount ΔLXa of the control amount for the detection light source 12 in the first period for X coordinate detection and the adjustment amount ΔLXb of the control amount for the detection light source 12 in the second period for X coordinate detection. Thus, the X coordinate of the target object Ob can be detected. According to such a method, even when ambient light other than the detection light L2, for example, an infrared component included in external light is incident on the photodetector 30, the detection values LXa and LXb are equal to the detection light source 12. When the control amount is adjusted, the intensity of the infrared component included in the ambient light is canceled out, so that the infrared component included in the ambient light does not affect the detection accuracy.

(Basic principle of Y coordinate detection)
In the optical position detection device 10 of the present embodiment, the first light intensity distribution L2Ya for Y coordinate detection and the second light intensity distribution L2Yb for Y coordinate detection described with reference to FIGS. 7C and 7D are used. Thus, the position in the Y-axis direction (Y coordinate) is detected. More specifically, the detection light sources 12A and 12C and the detection light sources 12B and 12D are driven in opposite phases. That is, as shown in FIG. 6C, in the first period for Y-coordinate detection, the detection light sources 12A and 12C are turned on, while the detection light sources 12B and 12D are turned off, as shown in FIG. A first light intensity distribution L2Ya for Y coordinate detection is formed. Next, in the second period for Y-coordinate detection, as shown in FIG. 6D, the detection light sources 12A and 12C are turned off, while the detection light sources 12B and 12D are turned on, as shown in FIG. A second light intensity distribution L2Yb for Y coordinate detection is formed. Accordingly, the Y-coordinate detection unit 52 compares the detection value LYa at the photodetector 30 in the first period for Y-coordinate detection with the detection value LYb at the photodetector 30 in the second period for Y-coordinate detection. The Y coordinate of the target object Ob can be detected by a method similar to the method of detecting the X coordinate.

(Basic principle of Z coordinate detection)
In the optical position detection device 10 of this embodiment, in order to detect the Z coordinate, all of the detection light sources 12A to 12D are turned on at the same time to form a Z coordinate detection light intensity distribution whose intensity changes monotonously in the Z-axis direction. To do. Therefore, when the target object Ob is arranged in the detection target space 10R, the detection light L2 is reflected by the target object Ob, and a part of the reflected light is detected by the photodetector 30. Here, since the Z coordinate detection light intensity distribution has a constant inclination distribution in the Z-axis direction, the Z coordinate of the target object Ob can be detected based on the detection intensity of the photodetector 30. .

(Coordinate detection using the reference light source 12R)
When performing the above coordinate detection, only the detection light L2 may be used. However, in the optical position detection device 10 of this embodiment, a reference light source 12R is provided. Therefore, when detecting the X coordinate and the Y coordinate of the target object Ob, the detection intensity of the reference light Lr at the photodetector 30 and the detection light reflected by the target object Ob instead of the differential between the detection light sources 12. The result of comparison with the detection intensity of the L3 photodetector 30 can be used. More specifically, the drive current for the detection light source 12 and the light detection when the reference light source 12R and some of the detection light sources 12 are differentiated so that the detection intensities at the photodetector 30 are equal. Target object using the difference or ratio of the drive current to the detection light source 12 when the reference light source 12R and the other part of the detection light source 12 are differentiated so that the detection intensities at the detector 30 are equal. The position of Ob can be detected.

  Further, when detecting the Z coordinate of the target object Ob, instead of the absolute value of the Z coordinate detection light intensity distribution, the detection intensity of the reference light Lr at the photodetector 30 and the detection light L3 reflected by the target object Ob. The result of comparison with the detection intensity at the photodetector 30 can be used. More specifically, the drive current for the detection light source 12 when the reference light source 12R and all the detection light sources 12 are differentiated so that the detection intensities at the photodetectors 30 are equal, and the detection The position of the target object Ob can be detected using the difference or ratio with respect to the drive current for the light source 12. According to such a method, when detecting the Z coordinate of the target object Ob, the infrared component included in the ambient light does not affect the detection accuracy.

  Furthermore, in this embodiment, the light source for detection 12 and the light source for reference 12R are driven by a common light source driving unit. For this reason, even if intensity fluctuations occur in the drive signals supplied to the detection light source 12 and the reference light source 12R, the position of the target object Ob can be detected without being affected by such intensity fluctuations.

(Main effects of this form)
As described above, in the optical position detection device 10 of this embodiment, the light incident portions 13e to 13h are provided at the corner portions 13a to 13d of the light guide plate 13, and the light guide plate 13 includes the light guide plate 13. A reflection portion 13r is provided so that the detection light L2 propagating through the inside faces toward the light exit surface 13s. For this reason, the detection light L2 incident from the light incident portions 13e to 13h is deflected toward the light emitting surface 13s by the reflecting portion 13r while traveling through the light guide plate 13, and is emitted from the light emitting surface 13s. Is done. As a result, a light intensity distribution of the detection light L2 is formed on the light exit surface 13s side with respect to the light guide plate 13. Further, the detection intensity of the detection light L3 by the photodetector 30 corresponds to the light intensity at the location where the target object Ob is located. Therefore, the position of the target object Ob can be detected based on the detection intensity of the detection light L3 detected by the photodetector 30. Here, since the light incident portions 13e to 13h are provided at the corner portions 13a to 13d of the light guide plate 13, the emission intensity from the light exit surface 13s is high at the corner portions 13a to 13d, and from the corner portions 13a to 13d. In this embodiment, the light guide plate 13 is provided with a distribution in which the density increases as the reflecting portion 13r moves away from the corner portions 13a to 13d. For this reason, the emission efficiency from the light emission surface 13s is high even at positions away from the corner portions 13a to 13d. Therefore, in the X-axis direction and the Y-axis direction along the light emitting surface 13s, a light intensity distribution in which the intensity decreases linearly from one side to the other side can be formed, and from the other side to the one side. A light intensity distribution can be formed in which the intensity decreases linearly. Therefore, the position of the target object Ob can be accurately detected by using the light intensity distribution of the detection light L2 formed by the light guide plate 13.

  In the present embodiment, the position detection unit 50 turns on some of the detection light sources arranged at two corners adjacent to each other in the circumferential direction among the plurality of detection light sources 12, while turning on the other corners. When the other detection light sources are turned off, the detection intensity of the detection light L3 at the photodetector 30 and a part of the detection light sources are turned off, while the other detection light sources are turned on. Based on the detection intensity of the detection light L3 detected by the photodetector 30, the position of the target object Ob is detected. Therefore, compared to the case where the detection light sources 12 are turned on one by one, the intensity of the detection light L2 is large, and a light intensity distribution in which the intensity varies linearly over a wide range can be formed. .

  In the present embodiment, in the light guide plate 13, the density of the reflecting portion 13r decreases from the center O13 toward the side portion 13n. In the light guide plate 13, the degree of increase in the density of the reflecting portion 13r from the corner portions 13a to 13d toward the center O13 is reflected from the corner portions 13a to 13d between the center O13 and the side portion 13n. The density of the portion 13r is smaller than the degree of increase. Therefore, when the intensity of the detection light L2 emitted from the two detection light sources 12 provided at the corners sandwiching the side 13n is synthesized in the vicinity of the side 13n of the light guide plate 13, the intensity changes linearly. A light intensity distribution is formed.

  Further, since the detection light L2 is infrared light, even when the detection target space 10R is set at a position overlapping the display surface of the display device 8, the detection light L2 does not hinder the visual recognition of the image. Further, even when the detection target space 10R is set at a position overlapping with the display surface of the display device 8, the wavelength of the detection light L2 and the display light are different from each other, so that the reflection unit 13r provided on the light guide plate 13 does not hinder the display of the image. .

[Other embodiments]
FIG. 9 is an explanatory diagram of another apparatus 100 with a position detection function to which the present invention is applied. In FIGS. 9A and 9B, the center of the light guide plate 13 and the center of the detection target space 10R are shifted. It is explanatory drawing in the case of being, and explanatory drawing in case the shape of detection object space 10R is a trapezoid.

  In the above embodiment, the light guide plate 13 and the detection target space 10R are both rectangular when viewed from the Z-axis direction, and the centers of both coincide with each other. However, in this embodiment, refer to FIG. As described below, the center of the light guide plate 13 and the center of the detection target space 10R are shifted. Even in such a case, in this embodiment, since the reflection portion 13r is formed with an appropriate distribution on the light guide plate 13, an appropriate light intensity distribution in which the intensity changes linearly in the entire region overlapping the light guide plate 13 can be formed. it can.

  For example, as shown in FIG. 9A, the drive circuit 81, 82, etc. are provided along the two sides of the display device 8, so that the center O13 (light guide plate 13) of the light guide plate 13 is provided. Of two imaginary lines connecting the corners located diagonally in FIG. 2 and the center O10 of the detection target space 10R (two imaginary lines connecting the corners located diagonally in the detection target space 10R). Even when the point of intersection is deviated, an appropriate intensity distribution can be formed. More specifically, light whose intensity decreases linearly from the end portion 10R1 on one side X1 in the X-axis direction of the detection target space 10R toward the end portion 10R2 on the other side X2 in the X-axis direction of the detection target space 10R. The intensity distribution and the light intensity distribution in which the intensity decreases linearly from the end 10R2 on the other side X2 in the X-axis direction of the detection target space 10R toward the end 10R1 on the one side X1 in the X-axis direction of the detection target space 10R. Can be formed symmetrically in the X-axis direction. A light intensity distribution in which the intensity decreases linearly from the end 10R4 on one side Y1 in the Y-axis direction of the detection target space 10R toward the end 10R3 on the other side Y2 in the Y-axis direction of the detection target space 10R; The light intensity distribution in which the intensity decreases linearly from the end 10R3 on the other side Y2 in the Y-axis direction of the detection target space 10R toward the end 10R4 on the one side Y1 in the Y-axis direction of the detection target space 10R It can be formed symmetrically in the direction.

  Further, as shown in FIG. 9B, the light guide plate 13 is rectangular, whereas the detection target space 10R is trapezoidal. The intersection of two imaginary lines connecting the corners located at the corners) and the center O10 of the detection target space 10R (the intersection of the two imaginary lines connecting the corners located diagonally in the detection target space 10R) Even in the case where there is a deviation, an appropriate intensity distribution can be formed. More specifically, light whose intensity decreases linearly from the end portion 10R1 on one side X1 in the X-axis direction of the detection target space 10R toward the end portion 10R2 on the other side X2 in the X-axis direction of the detection target space 10R. The intensity distribution and the light intensity distribution in which the intensity decreases linearly from the end 10R2 on the other side X2 in the X-axis direction of the detection target space 10R toward the end 10R1 on the one side X1 in the X-axis direction of the detection target space 10R. Can be formed symmetrically in the X-axis direction. A light intensity distribution in which the intensity decreases linearly from the end 10R4 on one side Y1 in the Y-axis direction of the detection target space 10R toward the end 10R3 on the other side Y2 in the Y-axis direction of the detection target space 10R; The light intensity distribution in which the intensity decreases linearly from the end 10R3 on the other side Y2 in the Y-axis direction of the detection target space 10R toward the end 10R4 on the one side Y1 in the Y-axis direction of the detection target space 10R It can be formed symmetrically in the direction.

8 ..Display device (viewing surface component) 10 ..Optical position detection device 10R ..Detection target space 12, 12A to 12D ..light source for detection, 12R ..light source for reference 13. Light plate, 13a to 13d, corner, 13m, outer peripheral side, 13n, side, 13r, reflector, 13s, light exit surface, 13t, back surface, 30, photodetector, 50, Position detection unit, 100 ... Equipment with position detection function, Ob ... Target object

Claims (7)

An optical position detection device for optically detecting the position of a target object,
A plurality of light sources for detection that emit detection light;
An outer peripheral side surface provided with a light incident part on each of a plurality of corners, into which detection light emitted from the detection light source is incident, and a rectangular light guide plate provided with a light output surface intersecting the outer peripheral side surface;
A photodetector for detecting the detection light reflected by the target object located in an emission space of the detection light from the light exit surface;
A position detector that detects the position of the target object based on the detection intensity of the detection light at the photodetector when the plurality of light sources for detection are sequentially turned on;
Have
The light guide plate is provided with a distribution in which a reflection portion that reflects the detection light propagating inside the light guide plate toward the light exit surface increases in density as the distance from the corner portion increases. An optical position detection device characterized by the above.   The position detector turns on a part of the light sources for detection arranged at the two corners adjacent to each other in the circumferential direction among the plurality of light sources for detection, while the other is arranged at the other corners. The detection intensity of the detection light at the photodetector when the detection light source is turned off, and the light when the other detection light sources are turned on while turning off the part of the detection light sources The optical position detection device according to claim 1, wherein the position of the target object is detected based on a detection intensity of the detection light at a detector.   The light guide plate is characterized in that the density of the reflection portion decreases from an intersection of two imaginary lines connecting corner portions located diagonally to the side portion among the plurality of corner portions. The optical position detection apparatus according to claim 2.   In the light guide plate, the degree of increase in the density of the reflection portion from the corner portion toward the intersection point is that the density of the reflection portion increases from the corner portion between the intersection point and the side portion. 4. The optical position detection device according to claim 2, wherein the optical position detection device is smaller than a degree of the movement.   Of the plurality of corners in the light guide plate, an intersection of two imaginary lines connecting corners located diagonally, and a detection target space set in an emission space of the detection light from the light exit surface 5. The optical position detection apparatus according to claim 1, wherein an intersection of two imaginary lines connecting corners positioned diagonally is shifted from each other.   The reflection part is dispersed in the irregularities formed on the back surface of the light guide plate facing the light output surface, the printing layer formed on the back surface of the light guide plate facing the light output surface, or dispersed in the light guide plate. The optical position detection apparatus according to claim 1, wherein the optical position detection apparatus is a particle.   The optical position detection apparatus according to any one of claims 1 to 6, wherein the detection light is infrared light.