JP2007072589A - Coordinate-input device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resolution of coordinate computation by reducing a difference between the maximum light quantity and minimum quantity of a detected signal waveform. <P>SOLUTION: Light is made incident to a retroreflection material corner short side part, to which an incident angle is small, by putting down a retroreflection material corner long side by one stage to raise a retroreflection light quantity of a minimum. A broad technical idea is that a structure is seen only from either an L or R sensor but not seen from the other due to a shade for each reteroreflection surface on the base side and for each notched front and back slopes, and a long-side left and right independence effect possibility (except a center part) is high. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coordinate input device capable of controlling a connected computer or writing a character, a figure, or the like, for example, by detecting an indication position indicated by an indication tool or a finger on the input screen, The present invention relates to a control method for controlling a coordinate input device, a control program, and a storage medium storing the control program.

  Conventionally, various types of coordinate input devices (touch panels and digitizers) have been proposed or commercialized as this type of coordinate input device. For example, touching the screen with a finger without using a special instrument or the like. A touch panel or the like that can easily operate a PC (personal computer) or the like is widely used.

  There are various methods such as those using a resistance film or using ultrasonic waves, but as a method using light, a retroreflective sheet is provided outside the coordinate input surface, and light is projected. The light from the means is reflected by the retroreflective sheet, and the light distribution is detected by the light receiving means, thereby detecting the direction of the light shielding area shielded by a finger or the like in the coordinate input area, and the light shielding position, that is, coordinate input. One that determines the coordinates of a position is known (for example, see Patent Document 1).

  In addition, the retroreflective member is arranged around the coordinate input effective area, and is retroreflected by the light reflecting means for projecting light to the sensor units provided at the two corners of the coordinate input effective area and the retroreflective plate. It is known that the light receiving means for receiving the received light is integrally configured, and the optical axis of the sensor unit is set to be inclined by approximately 45 ° in the in-plane direction of the coordinate input effective area (for example, Patent Document 2).

  However, retroreflective materials that are commercially available for road signs and the like have a high retroreflective efficiency, even if they have the widest angle characteristics, the efficiency decreases sharply at an incident angle of 30 to 45 degrees or more, Actually, the wide-angle characteristics of 45 degrees or more have very low retroreflective efficiency. Therefore, when used in this type of apparatus, a commercially available one can be used as it is when the input area is close to a square and the incident angle is in the range of 45 ° + α. However, the increasing aspect ratio in recent years is 16. : In the case of a horizontally long display such as 9 etc., there was a problem that the incident angle to the retroreflective member becomes large and sufficient reflected light cannot be obtained.

In order to solve such a problem, for example, in Patent Document 3, a sawtooth-like member is used in a portion where the incident angle becomes large, and the incident angle is reduced by attaching a retroreflecting material to the slope. Propose that. Further, Patent Document 4 proposes that a refractive member such as Fresnel is provided on the front surface of the retroreflective member to bend the direction of the light beam to reduce the incident angle.
US Patent No. USP 4507557 JP 2001-243002 A JP-A-11-110116 JP 2001-290484 A

  Here, a schematic configuration of this type of optical coordinate input device will be described with reference to FIG.

  In FIG. 19, reference numerals 2001L and 2001R denote left and right sensor units each having a light projecting means (light emitting means) and a light receiving means (detecting means). These sensor units 2001L and 2001R receive a control signal from a control / arithmetic unit 2002, which will be described later, and transmit the detected signal to the control / arithmetic unit 2002. 2002 is a control / arithmetic unit for controlling the entire optical coordinate input device. Reference numeral 2003 denotes a coordinate input effective area (schematically shown), which is an area in which this type of optical coordinate input device can detect a position input by an instruction means such as a finger or an indicator. Reference numeral 2004 denotes retroreflective means, which is arranged in a shape surrounding the three outer sides of the coordinate input effective area 2003 (a U-shape).

  The retroreflective means 2004 has a retroreflective surface that retroreflects incident light in the direction of arrival. The retroreflective means 2004 retroreflects the light projected from the left and right sensor units 2001L and 2001R in the range of θ ° (approximately 90 °) toward the sensor units 2001L and 2001R. The light retroreflected by the retroreflective means 2004 is detected one-dimensionally by the light receiving means of the sensor units 2001L and 2001R configured by a condensing optical system and a line CCD, and a signal indicating the light quantity distribution is controlled and calculated. Sent to unit 2002.

  With this configuration, when an input instruction is given to the coordinate input effective area 2003 by an instruction means such as a finger or an indicator, the light projected from the light projecting means of the sensor units 2001L and 2001R is transmitted by the instruction means. The light receiving means of the sensor units 2001L and 2001R that are blocked cannot detect light only from the part blocked by the indicating means (reflected light due to retroreflection), and as a result, light from any direction can be detected. It was possible to identify whether or not there was.

  That is, the control / arithmetic unit 2002 detects the light shielding range of the portion instructed to be input by the instruction means from the light amount change of the light projecting means of the left and right sensor units 2001L and 2001R, and determines the light shielding position from the information on the light shielding range. Each direction (angle) is derived. Further, a light shielding position (coordinates) is geometrically calculated from the derived direction (angle) and distance information between the sensor units 2001L and 2001R, and a PC (personal computer) connected to display means (not shown). ) Etc., the coordinate value is output via an interface such as USB.

  The retroreflective member constituting the retroreflective means 2004 used here is a bead-type retroreflective sheet having a retroreflective property by stacking spherical beads on the reflective surface, or an optical reflective surface. A retroreflective sheet or the like that causes a retroreflective phenomenon by regularly arranging corner cubes by machining or the like is used.

  In the coordinate input device having such a configuration, the light projected from the light projecting means of the sensor units 2001L and 2001R is retroreflected by the retroreflective means 2004, and the retroreflected light is received by the light receiving means ( (Line CCD).

  In FIG. 19, the horizontal line indicates the X axis, the vertical line indicates the Y axis, and O indicates the intersection coordinates (0, 0) between the X axis and the Y axis. The sensor units 2001L and 2001R are arranged at a predetermined distance apart from each other at a position parallel to the X axis and symmetrical to the Y axis of the coordinate input effective area 2003.

  FIG. 20 is a diagram showing the arrangement of each member (in the drawing, only the left sensor unit 2001L is shown, but the right sensor unit 2001R is also a symmetrical arrangement, and the following description is the same). 21 is a diagram schematically showing the output of the line CCD which is the light receiving means of the sensor unit 2001L.

  20, 2001L is a sensor unit, 2003 is a coordinate input effective area (coordinate input surface), 2004 is retroreflective means, (1), (2), (3), and (4) are light projecting means of the sensor unit 2001L. The direction of the light projected from each is shown.

  In FIG. 20, the angle between the light directed from the light projecting means of the sensor unit 2001L in the direction (2) and the upper side in the diagram of the coordinate input effective area 2003 is 45 °. ing.

  In FIG. 21, the horizontal axis indicates the pixel number (equivalent to angle information) [N] of the line CCD, and the vertical axis indicates the output signal level [V]. It is a level that cannot be detected, and the output level changes in the direction of signal level A as the detected light quantity increases. As shown in the figure, the amount of retroreflected light detected by the line CCD as the light receiving means does not become uniform depending on the angular direction. The main causes of such a phenomenon are as follows.

A) Light projection characteristics of the light projecting means of the sensor unit 2001L B) Distance from the light projecting means of the sensor unit 2001L to the retroreflective means 2004 C) Retroreflective characteristics of the retroreflective means 2004 Light projection of the light projecting means of the sensor unit 2001L The characteristics largely depend on the optical characteristics of the light projecting lens. However, in this type of coordinate input device, the output light of a light emitting element such as an infrared LED (light emitting diode) is output from the coordinate input effective area 2003. The light projecting lens is configured to project in a fan shape in the plane and substantially parallel to the coordinate input effective area 2003.

  FIG. 22 is a diagram schematically showing a configuration of a light projecting lens in the light projecting means of the sensor unit 2001L. In FIG. 22, reference numeral 2300 denotes a light projecting lens. FIG. 22A is a diagram of a light projection lens viewed from a direction perpendicular to the coordinate input effective area 2003, and FIGS. 22B and C are light projections viewed from a direction parallel to the coordinate input effective area 2003. It is a figure of a lens.

Generally, it has an axis of symmetry in the in-plane direction parallel to the coordinate input effective area 2003 (hereinafter, the principal ray direction, the direction of 1 in FIG. 22A), and the light from the light projecting means in the vertical direction is The light is projected as a light beam substantially parallel to the coordinate input effective area 2003 (in the arrow direction in FIG. 22B).
FIG. 23 is a diagram showing a light distribution of the light projection lens 2300 in the in-plane direction of the coordinate input effective area 2003. In FIG. 23, the vertical axis represents the light projection level of the light projection lens 2300, and the horizontal axis represents the light projection. The projection angle of the lens 2300 is shown respectively.

  FIG. 23 shows a light distribution that is symmetric in the principal ray direction 1). This projection distribution is determined by the curvature of the projection lens 2300 or the size of the effective pupil in the projection angle direction.

  In the direction perpendicular to the coordinate input effective area 2003, the projection lens 2300 is designed so as to be substantially parallel to the coordinate input effective area 2003 and the light flux does not spread. Spreads with the projection distance in the vertical direction of the coordinate input effective area 2003.

  Therefore, the light energy density decreases as the projection distance increases, and the amount of light incident on the retroreflective means 2004 in the direction perpendicular to the coordinate input effective area 2003 decreases. As a result, the retroreflected light from the direction perpendicular to the coordinate input effective area 2003 is reduced, and is detected by the light receiving means of the sensor unit 2001L as the distance from the light projecting means of the sensor unit 2001L to the retroreflective means 2004 becomes longer. Less light.

  Furthermore, if the principal ray in the direction perpendicular to the coordinate input effective area 2003 is not parallel to the coordinate input effective area 2003, the height changes with the distance from the light projecting means to the retroreflective means 2004 of the sensor unit 2001L. The amount of light projected to the retroreflective unit 2004 also depends on the distance from the light projecting unit of the sensor unit 2001L to the retroreflective unit 2004 (see FIG. 22C).

  FIG. 24 is a partially enlarged view of the reflection surface of the bead type retroreflective means 2004, and FIG. 25 is a diagram showing the retroreflective characteristics of the retroreflective means 2004 arranged with the incident angle as a parameter.

  In FIG. 25, the horizontal axis represents the incident angle θ °, and the vertical axis represents the ratio of the retroreflected light quantity to the incident light quantity (retroreflection efficiency).

  24 and 25, if the incident angle θ ° is small, the amount of light that is nearly 100% can be retroreflected. However, when the incident angle θ ° exceeds 30 °, for example, the amount of light recurs rapidly. It is understood that the reflection efficiency is reduced.

  Based on the above, the light quantity distribution in FIG. 21 will be described.

  Here, in order to simplify the explanation, it is assumed that the light projection distribution in the in-plane direction of the coordinate input effective area 2003 of the light projecting means is substantially constant (the angle dependency is small) as shown in FIG. At this time, in FIG. 20, the light projected in the direction (1) is in the state where the distance to the reflecting surface of the retroreflective means 2004 is the shortest and the incident angle θ ° is small. As it goes in the direction of 2), the distance to the reflection surface of the retroreflective means 2004 and the incident angle θ ° to the reflection surface gradually increase.

  However, substantially constant retroreflective efficiency is obtained until the incident angle θ ° on the reflecting surface of the retroreflective means 2004 reaches about 30 °. In such a state, in FIG. As the angle in the direction 1) is changed to the angle in the direction (2), the amount of light detected by the light receiving means of the sensor unit 2001L gradually increases. Then, the incident angle θ ° to the reflection surface of the retroreflective means 2004 becomes larger than 30 °, and the retroreflected light rate is extremely lowered as it goes from the direction (2) to the direction (3) in FIG. Accordingly, the amount of light detected by the light receiving means of the sensor unit 2001L is extremely reduced accordingly.

  Furthermore, in the process in which the direction of the light beam in FIG. 20 changes from (2) → (3) → (4), the angle of the reflection surface of the retroreflective means 2004 changes rapidly in the direction of the corner region of (3). That is, the incident angle θ ° to the retroreflective means 2004 is large at the position (3) −, whereas the incident angle θ ° becomes a smaller value at the position (3) +, and the incident angle θ ° Continuation occurs. As a result, the discontinuity of the light amount distribution occurs at the position (3) in FIG. Then, when the light ray in FIG. 20 changes from the direction (3) to the direction (4), the distance to the reflecting surface of the retroreflective means 2004 becomes gradually smaller, so that the incident angle θ ° incident on the reflecting surface becomes 0 °. Accordingly, the light amount level detected by the light receiving means of the sensor unit 2001L gradually increases.

  However, although the incident angle θ ° of the light ray in the direction (1) and the direction (4) in FIG. 20 to the retroreflective means 2004 is substantially equal, the light reflecting means of the sensor unit 2001L reflects the reflective surface of the retroreflective means 2004. Therefore, the detected light amount level of the light beam in the direction (4) is smaller than the detected light amount level of the light beam in the direction (1).

  From the above, it is understood that this light quantity distribution varies greatly depending on the aspect ratio of the coordinate input effective area 2003 and the arrangement positions of the sensor units 2001L and 2001R with respect to the coordinate input effective area 2003.

  In particular, when the aspect ratio of the coordinate input effective area 2003 is changed from 4: 3 to 16: 9, the incident angle θ ° to the retroreflective means 2004 becomes large and the retroreflective characteristics are deteriorated. The light quantity level of the light beam detected in the direction is extremely lowered.

  On the other hand, the line CCD as the light receiving means of the sensor units 2001L and 2001R will be described. In order to detect the light shielding portion with high accuracy, the detection signal level is electrical even if the light beam in FIG. 20 is in the direction (1). Must not saturate.

  Therefore, even if the light beam in FIG. 20 is in the direction (1), the shutters of the line CCDs of the sensor units 2001L and 2001R are controlled or the light projecting means of the light projecting means so that the detection signal level is not electrically saturated. It is necessary to control the current flowing through the light projecting element.

  However, if the detection signal level is controlled so as not to cause electrical saturation, the signal level of the light beam in the direction (3) in FIG. 20 is extremely reduced, and even if the signal cannot be detected or the signal can be detected. Problems such as signal instability due to noise occur.

  That is, if a signal cannot be detected in that direction (direction (3)), the coordinates cannot be calculated, and signal degradation due to noise is constant when, for example, a predetermined position is continuously indicated by an instruction means such as a finger or an indicator. Since the coordinate value cannot be output, there arises a problem that the coordinate calculation resolution is greatly reduced.

  Further, the conventional example in which a saw-toothed surface is provided at a part of the periphery of the screen is improved by substantially reducing the incident angle by attaching a retroreflecting material to the slope. As shown in FIG. 19, the light projecting means and the light receiving means have a retroreflective material, which is a retroreflective means of a rectangular coordinate input area, as shown in FIG. Installed near both ends. The retroreflective member attached to the short side in the vicinity of the light projecting unit and the light receiving unit is not a retroreflective object because it is outside the field of view of the light receiving unit, and the two opposite sides of the light projecting unit and the light receiving unit are retroreflective targets. It becomes. Taking the sensor unit 2001L, which is a light projecting means and a light receiving means, as an example, the retroreflective target side is the short side (region from FIG. 19A to D) and the long side (region from FIG. 19A) in the vicinity of 2001R. (Region to C). Here, since the short side (the region from A to D in FIG. 19) is outside the field of view of the sensor unit 2001R, the configuration in which the sawtooth surface is provided effectively enters the sensor unit 2001L alone. Demonstrate the effect of improving angular characteristics. On the other hand, since the long side (the region from A to C in FIG. 19) is within the shared field of view with the sensor unit 2001R, for example, the region A originally has the longest distance to the side with respect to the sensor unit 2001L. When the retroreflective surface is formed by parallel planes, the incident angle is the largest and the detected light amount level is the smallest. On the other hand, even in the same area A, the sensor unit 2001R has the shortest distance on the side. When the retroreflective surface is formed of parallel planes, the sensor unit is different from each other in such a manner that the incident angle is the smallest and the detected light amount level is the largest. However, in the above-described conventional example in which a uniform serrated surface is provided, both adjacent serrated surfaces are retroreflective objects of the same light projecting unit and light receiving unit. Although the amount of retroreflected light increases, the amount of retroreflected light decreases on the one side with a large incident angle, and the total reflected light amount characteristic is determined by the apportionment of each area of the plus and minus surfaces. Therefore, there is a drawback that the improvement effect is limited.

  In other words, the improvement in the conventional detected light quantity level was most demanded for the long side of the common field of view from the two light projecting means and the light receiving means, in particular, FIG. 19A, FIG. 20 (3), FIG. However, there is a problem that the efficiency of the improvement effect is low.

  An object of the present invention is to provide a coordinate input device capable of improving the coordinate calculation resolution. Another object is to reduce the difference (dynamic range) in the light amount distribution of the detection level.

  In order to achieve the above object, retroreflective means for retroreflecting incident light installed around three sides of a rectangular coordinate input area and near both end corners of one side where the retroreflective means is not provided. A light projecting unit that projects a light beam toward the retroreflective unit, and a light receiving unit that receives the light beam retroreflected by the retroreflective unit, and the light beam projected by the light projecting unit by the instruction unit A coordinate input device for calculating the position coordinates of the light-shielding portion by the instruction means based on a change in the light amount distribution obtained from the light-receiving means caused by shielding light, and the retro-reflecting means on the opposite side of the non-installed side of the retro-reflecting means Is composed of a plurality of retroreflective surfaces, and all or a part of the retroreflective surface on the opposite side has a retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means. Unlike the retroreflective surface according to the light projecting means and light receiving means, wherein the retroreflective surfaces according to the light projecting means and said light receiving means with each other are arranged so as to be non-covalent.

  According to the present invention, the two light projecting means and the light receiving means are provided for the long side, particularly the corner region, which has a common visual field from the two light projecting means and the light receiving means for which improvement of the detected light amount level is most demanded. Since the amount of retroreflected light can be controlled independently, the difference between the maximum light amount and the minimum light amount of the detection signal waveform detected by the light receiving means can be reduced, so that the coordinate calculation resolution can be improved. it can.

  Hereinafter, an embodiment of a coordinate input device of the present invention will be described with reference to FIG.

(First embodiment)
First, a first embodiment will be described with reference to FIG.

  FIG. 1 is a diagram showing the configuration of the coordinate input device according to the first embodiment. In FIG. 1, the same parts as those in FIG.

  1 differs from FIG. 19 in that the retroreflective means on the long side (area extending from area A to area C in the figure) has a retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means. Unlike the retroreflecting surfaces related to the other light projecting means and the light receiving means, the retroreflecting surfaces related to the light projecting means and the light receiving means are arranged so as not to be shared. That is, the light transmission member 1001 is added to the configuration of 19. Here, the retroreflective means is different from the retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means, unlike the retroreflective surface related to the other light projecting means and the light receiving means. As shown in the figure, the retroreflective surface related to the light receiving means is arranged so as not to be shared, as shown in the figure, from one sensor unit constituted by the light projecting means and the light receiving means to radiate in the long side direction which is the opposite side. A retroreflective surface for the other sensor unit is formed so that the inclination with respect to the long side becomes gentle in parallel to the angle direction of the straight line, that is, as the distance from the sensor unit increases. Specifically, the retroreflective surface arranged in parallel to the angle direction of the straight line radiated from the sensor unit 2001L in the long side direction naturally has no projection surface perpendicular to the light flux related to the sensor unit 2001L, so the retroreflective surface Although no light is generated, it becomes a retroreflective surface for the other sensor unit 2001R. Similarly, the retroreflective surface arranged parallel to the angle direction of the straight line radiated from the sensor unit 2001R in the long side direction has no projection surface perpendicular to the light flux related to the sensor unit 2001R, but no retroreflected light is generated. This is a retroreflective surface for the other sensor unit 2001L. As a result, the surface configuration of the retroreflective means on the long side (area extending from area A to area C in the figure) of the opposite sides of the sensor unit 2001L and the sensor unit 2001R is the same as the light projecting means and the light receiving means of the sensor unit 2001L. The retroreflective surface related to the incidence and reflection of light is different from the retroreflective surface related to the light projecting means and the light receiving means of the sensor unit 2001R, and the retroreflection surface related to the incidence and reflection of the light projecting means and the light receiving means of the sensor unit 2001R. The reflective surface is different from the retroreflective surface related to the light projecting means and the light receiving means of 2001L so that the retroreflective surfaces related to the light projecting means and the light receiving means of the sensor unit 2001L and the sensor unit 2001R are not shared. Will be placed.

By adopting the configuration of the retroreflective surface of the retroreflective means described above, it is possible to independently cope with the retroreflective characteristics independently required for each sensor unit in each region of the long side. Actually, the inclination with respect to the long side becomes gentle as it goes away from the sensor unit in parallel with the angle direction of the straight line radiated from the one sensor unit composed of the light projecting means and the light receiving means to the long side direction which is the opposite side. In addition, when the retroreflective surface for the other sensor unit is formed, the surface A in the conventional plane configuration of the region A in FIG. Verify the effect in the comparison. In the retroreflective surface for the sensor unit 2001L, the surface A in the conventional planar configuration is the surface G in the figure due to the configuration of the present invention. As a result, when the incident angle is the conventional surface A with respect to the incident light flux indicated by the arrow to the region A in the figure, the sensor unit 2001L has an angle of E in FIG. Becomes ∠F in the figure. Here, geometrically, clearly ∠E> ∠F
Therefore, when the incident angle is reduced, the retroreflective efficiency is improved as compared with the conventional case, and the retroreflected light is increased.

  On the other hand, the incident angle of the sensor unit 2001R with respect to the incident light flux indicated by the arrow to the region A in the figure is approximately 0 ° in the case of the conventional surface A, but the surface B is ∠H. Here, geometrically, when the incident angle is obviously increased, the retroreflected light is reduced as compared with the conventional case.

  Further, the retroreflective surface G for the sensor unit 2001L is not a retroreflective surface for the sensor unit 2001R, and similarly, the surface B for the sensor unit 2001R is not a retroreflective surface for the sensor unit 2001L. The characteristics are improved independently and efficiently.

  The light transmitting member 1001 can transmit light of a specific wavelength only, prevents unnecessary light from being transmitted, and prevents the retroreflective means 2004 from being directly exposed to the outside. Part of product appearance). That is, the light transmissive member 1001 is disposed along the inside of the retroreflective means 2004 and with a predetermined interval between the reflective surfaces so as to cover the entire reflective surface of the retroreflective means 2004.

  By providing the light transmissive member 1001 in this way, even when “dust” and “dust” are accumulated on the light transmissive member 1001 over time when used as a product, the light transmissive member 1001 is provided. The user can easily remove the accumulated “dust” and “dust”. As a result, it becomes easy to maintain the optical characteristics of the retroreflective means 2004 semipermanently, and a highly reliable coordinate input device can be realized.

  The light retroreflected by the retroreflective means 2004 is detected one-dimensionally by the light receiving means of the sensor units 2001L and 2001R constituted by a condensing optical system and a line CCD, and the light quantity distribution data is controlled / calculated unit 2002. Sent to.

  The coordinate input effective area 2003 described above can be used as an interactive input device by being configured by a display screen of a display device such as a PDP, a rear projector, or an LCD panel.

  With this configuration, when an input instruction is given to the coordinate input effective area 2003 by an instruction means such as a finger or an indicator, the light projected from the light projecting means of the sensor units 2001L and 2001R is transmitted by the instruction means. The light receiving means of the sensor units 2001L and 2001R that are shielded from light cannot detect light only from the light shielding part (reflected light from the retroreflective means 2004) that is shielded by the instruction means. It is possible to determine whether or not it has been detected.

  That is, the control / arithmetic unit (setting unit) 2002 detects the light shielding range of the portion instructed to be input by the instruction unit from the change in the light amount from the light projecting unit of the left and right sensor units 2001L and 2001R. The direction (angle) of the light shielding position is derived from the information. Furthermore, the coordinate position on the coordinate input effective area 2003 is calculated from the derived direction (angle) and the distance information between the sensor units 2001L and 2001R, and a PC (personal computer) connected to a display device (not shown). A coordinate value is output to a computer or the like via an interface such as a USB.

  In this way, it is possible to draw a line on the display screen of the display device by an instruction means such as a finger or an indicator, and control the PC by operating an icon on the display screen.

  In the present embodiment, when the light quantity distribution from the light projecting means of the sensor units 2001L and 2001R is a substantially uniform light distribution, the angle range in which the light reception distribution is maximum in the long side direction in FIG. In the range, the light distribution by the light projecting means is discontinuously dimmed, and the distribution becomes asymmetric with respect to the optical axis.

  Further, the corners formed in the diagonal direction of the coordinate input effective area 2003 are formed by the retroreflective means 2004.

  Further, the corner formed in the diagonal direction of the coordinate input effective area 2003 is formed of a light transmitting member 1001 that protects the retroreflective means 2004.

  Further, the corners formed in the diagonal direction of the coordinate input effective area 2003 are light transmissive members 1001 and are composed of an apparatus housing.

  Further, the light beam direction from the light projecting point (light emitting point) of the light projecting unit of the sensor units 2001L and 2001R toward the corner portion composed of the retroreflective unit 2004 formed in the diagonal direction of the coordinate input effective area 2003, and the light projecting It is desirable that the light beam directions from the projection point of the means toward the corner portion constituted by the light transmitting member 1001 formed in the diagonal direction of the coordinate input effective area 2003 are different from each other.

  Further, the maximum level of the amount of light reflected from the reflection surface of the long-side retroreflective means 2004 provided in the horizontal direction of the coordinate input effective area 2003 and detected by the light receiving means of the sensor units 2001L and 2201R, and the coordinate input effective The long-side retroreflecting surface so that the maximum level of the amount of light reflected from the reflecting surface of the short-side retroreflecting unit 2004 provided in the vertical direction of the region 2003 and detected by the light-receiving unit is equal to each other. It is desirable to arrange the light quantity and set the light quantity distribution.

  Further, the retroreflective means 2004 is provided around the coordinate input effective area 2003 as described above and recursively reflects incident light.

  Further, the light projecting means of the sensor units 2001L and 2201R project a light beam in a fan shape toward the retroreflective means 2004 in a direction substantially parallel to the surface of the coordinate input effective area 2003 and in the in-plane direction of the coordinate input effective area 2003.

  Hereinafter, the configuration and operation of each part will be described.

<Description of sensor units 2001L and 2201R>
FIG. 2 is an exploded perspective view of the sensor units 2001L and 2201R and shows a configuration example of the light projecting means and the light receiving means in the sensor units 2001L and 2201R.

  In FIG. 2A, reference numeral 30 denotes a light projecting means, which includes an infrared LED (light emitting diode) 31 that emits infrared light and a light projecting lens 32, and the light emitted from the infrared LED 31 is transmitted by the light projecting lens 32. Then, light is projected in a fan shape in the in-plane direction of the coordinate input effective area 2003 substantially parallel to the surface of the coordinate input effective area 2003.

  FIG. 3A is a front view of the sensor units 2001L and 2201R in the assembled state, and the arrows in FIG. 3 indicate that the light from the light projecting means 30 is distributed in a fan shape in the in-plane direction of the coordinate input effective area 2003. Is shown. FIG. 3B is a view of FIG. 3A viewed from the side. Similarly, the light is projected as a light beam restricted in the vertical direction substantially parallel to the surface of the coordinate input effective area 2003, and is mainly displayed. Fig. 6 shows a state in which light is projected to the retroreflective means 2004.

  Referring back to FIG. 2A again, 40 is a light receiving means, which is a one-dimensional line CCD 41, a condensing lens 42 as a condensing optical system, an aperture 43 for roughly limiting the incident direction of incident light, visible light, etc. It comprises an infrared filter 44 that prevents the excess light from entering. The light projected by the light projecting means 30 is retroreflected by the retroreflecting means 2004, passes through the infrared filter 44 and the diaphragm 43, and is collected on the surface of the detection element group in the line CCD 41 by the condenser lens. Focused.

  In FIG. 2A, 51 is a lower casing, 52 is an upper casing, and the diaphragm 43, the upper casing 52, and the lower casing 51 pass only retroreflected light from the retroreflective means 2004. In addition, the visual field in the height direction (the height direction from the surface of the coordinate input effective area 2003) is mainly limited, and the visual field in the in-plane direction of the coordinate input effective area 2003 is roughly limited. Yes.

  In the present embodiment, the lower housing 51 and the diaphragm 43 are formed integrally with each other, but it goes without saying that these may be formed of separate members.

  FIG. 4 is a diagram for explaining an optical path from when the light from the light projecting means 30 of the sensor units 2001L and 2201R is retroreflected by the retroreflective means 2004 and detected by the line CCD 41 as the light receiving means. In the figure, the same parts as those in FIGS. 2A and 3 are denoted by the same reference numerals.

  4A is a front view seen from the direction perpendicular to the surface of the coordinate input effective area 2003, and FIG. 4B is a side view thereof.

  In FIG. 4A, the light of the light projecting means 30 projected in the substantially 90 ° direction described above is retroreflected by the retroreflecting means 2004 and passes through the infrared filter 44 and the aperture 43 to the condenser lens 42. Although the light is incident, the light forms an image on the pixel 45 of the line CCD 41 in accordance with the incident angle with respect to the condenser lens 42 (see FIG. 4B). Accordingly, since the output signal of the line CCD 41 outputs a light amount distribution corresponding to the incident angle of the retroreflected light, the pixel number of the line CCD 41 indicates angle information.

  In the case of the present embodiment, the light projecting means 30 and the light receiving means 40 as the detecting means are arranged so as to overlap each other, and the distance L (see FIG. 3B) is recursed from the light projecting means 30. This is a sufficiently small value compared to the distance to the reflection means 2004, and even if the distance L is present, a sufficient retroreflected light can be detected by the light receiving means 40 as the detection means.

  FIG. 5 is a diagram showing the relationship between the pixel number N of the line CCD 41 observed by the light receiving optical system in the coordinate input device according to the present embodiment and the angle θ to be derived. In FIG. The angle θ to be output, and the horizontal axis indicates the pixel number of the line CCD 41.

  Here, the normal direction of the line CCD 41 and the symmetry axes βL and βR of the light receiving optical system are made to coincide with each other, and the direction is defined as an angle of 0 °. At this time, if the measurement angle range is small, the relationship between the pixel number N of the line CCD 41 and the measurement angle θ is, for example, easy to design and manufacture a condenser lens 42 having good linearity. When the angle range becomes large, it becomes difficult to remove optical distortion generated at the end of the condenser lens 42, and a large error occurs in the measurement angle.

  Therefore, as shown in FIG. 1, the symmetry axes βL and βR of the light receiving optical system are set in a direction inclined approximately 45 ° with respect to the X axis of the coordinate input effective area 2003, or coordinate input effective with the sensor units 2001L and 2001R. It is preferable to provide the symmetry axes βL and βR of the light receiving optical system in the angle bisector direction of the light beam A and the light beam B determined by the region 2003. By setting in this way, the measurement angle range of the light receiving optical system is at least ± 45 ° or less.

  On the other hand, the coordinate input device according to the present embodiment is arranged so as to overlap the display display (display device), so that the handwriting by the instruction means such as a finger or an indicator is displayed on the display display. It is possible to realize various usability.

  Regarding the trend of display, the aspect ratio (aspect ratio) of the display area is mainly 4: 3, but the aspect ratio of 16: 9 is becoming widespread as seen in full HD images and the like. That is, the coordinate input effective area 2003 of the coordinate input device has a horizontally long specification so as to correspond to it.

  Accordingly, the incident angle with respect to the retroreflective unit 2004 or the distance to the retroreflective unit 2004 is optically stricter. As described in the section of the problem, the maximum signal level of the detection signal waveform shown in FIG. The difference from the minimum signal level is larger. Therefore, the signal difference cannot be covered by the dynamic range of the line CCD 41, and as a result, the coordinate calculation resolution is lowered or the coordinate calculation is impossible.

  The present invention has been made in view of this point. As described above, the feature of the present invention is that, on all or part of the retroreflective surface of the present apparatus, the incidence of one of the light projecting means and the light receiving means and The retroreflective surface related to reflection is different from the retroreflective surface related to the other light projecting means and the light receiving means, and the retroreflective surfaces related to the light projecting means and the light receiving means are not shared. It is.

  FIG. 6 is a diagram for explaining the effect of the present invention. FIG. 1 shows in-plane symmetric axes βL and βR parallel to the coordinate input effective area 2003 of the light receiving means 40 in the sensor units 2001L and 2001R. As shown, the coordinate input effective area 2003 is inclined by 45 ° in the X-axis direction, the direction is defined as an angle of 0 °, and the sign of the angle is clockwise in the left sensor unit 2001L and in the right sensor unit 2001R. Although not shown, it is defined counterclockwise (see FIG. 1).

  6A shows an in-plane symmetric axis parallel to the coordinate input effective area 2003 of the light receiving means 40 (a direction inclined by 45 ° in the X-axis direction of the coordinate input effective area 2003, and FIG. The light projecting level of the light projecting means 30 is such that the symmetry axis of the light projecting means 30 is provided in the same direction as that of the angle 0 ° and the light distribution is substantially uniform (angle dependency is small). The vertical axis indicates the level ratio, and the horizontal axis indicates the angle.

  At this time, FIG. 6B shows the level ratio of the signal output from the light receiving means 40 in the optical component arrangement as shown in FIG. 1, where the vertical axis indicates the level ratio and the horizontal axis indicates the angle. , Respectively. As shown in FIG. 6 (B), it is formed by the retroreflective means 2004 facing from the light projecting (light emitting) point of the light flux projected by the light projecting means 30 in the vicinity of the angle -14 ° of the region A. The retroreflective level of the light beam traveling toward the corner (the light beam traveling from the left sensor unit 2001L toward the region A in FIG. 1) is the smallest. That is, the light beam toward the region A is detected by the light receiving unit 40 because the distance to the reflecting surface of the retroreflecting unit 2004 is long and the incident angle to the reflecting surface of the retroreflecting unit 2004 is large. The light level decreases.

  On the other hand, in FIG. 1, a light beam (approximately + 45 ° direction in terms of angle) from the left sensor unit 2001L in the C direction is close to the retroreflective unit 2004 and has a small incident angle. A sufficient light level can be obtained by 40.

  On the other hand, in FIG. 1, a light ray traveling in the D direction from the left sensor unit 2001 </ b> L (converted into an angle of approximately −45 °) has an incident angle to the retroreflective means 2004 in the C direction from the left sensor unit 2001 </ b> L. Although the distance to the retroreflecting unit 2004 is large, the light amount level obtained by the light receiving unit 40 is smaller than the light amount level of the light beam traveling in the direction C.

  Therefore, the level difference of the detected light amount reaches about 10 times, and considering the dynamic range of the line CCD 41, the signal detected in the direction A in FIG. .

  Furthermore, as already described in the problem to be solved by the invention, the retroreflective level detected from the same corner in the A direction is the smallest value. The incident angle with respect to the retroreflective means in the long side direction is ∠E as shown in the figure with respect to the light beam projected in the A direction, and the incident angle with respect to the retroreflective means in the short side direction is 90 ° −∠E. However, in the coordinate input effective area 2003 corresponding to a display area having an aspect ratio (aspect ratio) of, for example, 16: 9, (90 ° −∠E) <∠E is self-evident, and therefore the retroreflective means n. Due to the incident angle characteristics, the amount of retroreflected light is greatly stepped as shown in FIG.

  Therefore, when position detection is performed by a method to be described later, the coordinate calculation resolution in that direction is extremely reduced. Furthermore, this becomes most noticeable with respect to the diagonal portion related to the long side where the incident angle to the retroreflective means is maximum.

  The present invention has been made in view of this point, and an object thereof is to improve the difference in detection signal level and improve the coordinate calculation resolution.

  FIG. 6B shows the relationship between the detection signal level and the CCD pixel number in the conventional coordinate input apparatus as described above. FIG. 21 shows the light projecting means 30 and the light receiving means 40 constituting the sensor unit on the horizontal axis. The coordinate axis in the in-plane direction parallel to the coordinate input effective area 2003 (the direction inclined 45 ° to the X axis direction of the coordinate input effective area 2003) is the angle when the angle is equivalent to the 0 ° direction, and the vertical axis is the light projection It is a figure which shows the detection level ratio in the case of distribution. As the retroreflection range targeted by the sensor unit, an angle region corresponding to the long side is an angle range from A to C in the drawing, and an angle region corresponding to the short side is an angle range from A to D in the drawing. As described above, in the corner area A of the long side targeted by the sensor unit, the minimum detection level is obtained.

  FIG. 6C shows a retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means as shown in FIG. Unlike the reflection surface, the detection distribution level when the retroreflection surfaces related to the light projecting unit and the light receiving unit are arranged not to be shared is shown. As shown in the figure, there is no change in the detection level distribution on the short side, but for the corner region A on the long side, the amount of retroreflected light increases because the incident angle is small as described above. In the region C, on the contrary, the incident angle increases, so the amount of retroreflected light decreases. As a total, the difference between the minimum value and the maximum value of the detection level for the target sensor unit is reduced, and the dynamic range is improved. A further characteristic effect of the present invention is that this improvement effect occurs independently for one sensor unit, the effect does not affect the other sensor unit, and for the other sensor unit, In addition, the same improvement effect on the detection level distribution appears. Therefore, the improvement effect on the detection level distribution can be efficiently obtained as the entire apparatus including all the sensor units.

  FIG. 7A shows another embodiment of the present invention. The retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means shown in FIG. Unlike the retroreflective surface related to the light receiving means, the arrangement is made such that the light reflecting means and the retroreflective surfaces related to the light receiving means are not shared. Here, only the line indicating the light beam direction and the retroreflective surface, which are elements that make the difference of the other embodiments of the present invention clear, are shown, but the basic configuration (not shown) is the same as in FIG. As shown in the figure, in the region A, for example, the retroreflective surface B arranged as a surface parallel to the straight line from the sensor unit 2001L to the corner is a surface arranged with a larger inclination angle with respect to the long side. Configured as B ′. As described above, the retroreflective surface B ′ is not related to the retroreflection related to the sensor unit 2001L. Therefore, according to the present embodiment, the sensor unit 2001L, that is, the incident angle in the diagonal direction of the light projecting unit and the light receiving unit. It does not affect the retroreflective properties involved. However, the retroreflective surface B ′ has a large incident angle with respect to the sensor unit 2001R, so the amount of retroreflected light is small due to the incident angle characteristics of the retroreflective means. As shown in the drawing, not only the surface B ′ but also other retroreflective surfaces are arranged with a larger inclination angle with respect to the longer side than in the first embodiment, and the same configuration is provided near the region C. Also, the incident angle with respect to the sensor unit 2001L is configured to be large.

  FIG. 7B shows the detection distribution level in the case of the other embodiment (second embodiment) in the same format as FIGS. 6B and 6C. According to this embodiment, the minimum detection level itself does not change as in the first embodiment described above, but the inclination angle is increased independently only for the retroreflective target sensor unit that becomes the maximum level region, and therefore the incident angle. As a result, the retroreflected light level can be lowered. As a result, as shown in the figure, the difference between the maximum and minimum levels can be reduced to further improve the dynamic range.

  More preferably, the incident angle is decreased in the vicinity of the region A as it goes from the region A to the region C, and in the vicinity of the region C as it moves from the region C to the region A. By using such a retroreflective surface, the incident angle can be reduced as the distance from the sensor unit gradually increases, and the detection level distribution can be smoothed more smoothly.

  FIG. 7C shows still another embodiment of the present invention. Like the second embodiment, FIG. 7C shows recursion related to incidence and reflection of one of the light projecting means and the light receiving means shown in FIG. The reflection surface is different from the retroreflective surface related to the other light projecting means and the light receiving means, and the retroreflective surface related to the light projecting means and the light receiving means is not shared. It is a thing. Here, only the line indicating the light beam direction and the retroreflective surface, which are elements that make the difference of the other embodiments of the present invention clear, are shown, but the basic configuration (not shown) is the same as in FIG. As shown in the drawing, in the region A, for example, the retroreflective surface G arranged as a plane parallel to the straight line from the sensor unit 2001R to the long side of the retroreflective means is related to the angle of the surface and further to the long side. The surface G ′ is arranged with a small inclination angle. In this case, since there is no change in the arrangement of the retroreflective surface B, only the tip of the retroreflective surface B on the input region side protrudes, and the retroreflective surface G ′ is viewed from the sensor unit 2001R. The retroreflecting surface G ′ is not involved in the retroreflection of the sensor unit 2001R. Therefore, according to the present embodiment, the retroreflective characteristics relating to the incident angle of the sensor unit 2001R, that is, the long side region having the shortest distance between the light projecting unit and the light receiving unit are not affected. However, the retroreflective surface G ′ becomes smaller with respect to the sensor unit 2001L as the incident angle approaches 0 °, and therefore the amount of retroreflected light increases due to the incident angle characteristics of the retroreflective means. As shown in the drawing, not only the surface G ′ but also the retroreflective surface for the other nearby sensor unit 2001L is arranged with a smaller inclination angle with respect to the longer side than in the first embodiment. Is configured so that the incident angle with respect to the sensor unit 2001R is small even in the vicinity of the region C.

  FIG. 7D shows a detection distribution level in the same format as FIG. 7B in the case of another embodiment (third embodiment). According to the present embodiment, the maximum detection level itself does not change as in the first embodiment described above, but the inclination angle is reduced independently only for the retroreflective target sensor unit that is the minimum level region, and therefore the incident angle. As a result, the retroreflected light level can be increased, and as a result, the maximum and minimum level difference can be reduced and the dynamic range can be further improved as shown in the figure.

  More preferably, the incident angle increases in the vicinity of the region A as it goes from the region A to the region C, and in the vicinity of the region C as it goes from the region C to the region A. By using such a retroreflective surface, the incident angle can be reduced as the distance from the sensor unit gradually increases, and the detection level distribution can be smoothed more smoothly.

  In FIG. 7E, the retroreflective means constituting the surface B has a thickness, and the thickness is detected as a surface G ″ at the end of the surface B as a shadow that cannot be ignored with respect to the detection resolution in the sensor unit 2001L. In order to prevent this, the inclination angle of the surface G ″ at the end of the surface B is formed as an angle parallel to the straight line from the sensor unit 2001R to the long side, and retroreflective means is also attached to the surface G ″. Shows the configuration. With this configuration, even if the retroreflective means constituting the surface B has a thickness, the shadow does not occur on the surface G ″ and does not affect the sensor unit 2001R. Absent. This is the same not only for the surface G ″ but also for all other retroreflective surfaces. Of course, when the thickness of the retroreflective means constituting the surface B is negligibly small relative to the sensor unit. This is not the case.

  In the above, the embodiment in which the retroreflective incident angle is controlled mainly by the inclined arrangement of the retroreflective surface has been described. The tilt direction of the retroreflective surface is the direction in which the rotation axis of the tilt is perpendicular to the input area as described above. In addition to the inclination, the rotation axis of the inclination may be an inclination parallel to the input area.

  In the above embodiment of the present invention, in order to reduce the difference in the detected light amount distribution and make the distribution uniform, the retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means is the other. Unlike the retroreflective surfaces related to the light projecting means and the light receiving means, the inclination angle of the retroreflective means is basically based on a configuration in which the retroreflective surfaces related to the light projecting means and the light receiving means are not shared. Thus, the configuration for controlling the incident angle to the retroreflective means has been shown. Furthermore, as a fourth embodiment, in addition to this method, the effective area related to retroreflection of the retroreflective means is controlled by utilizing the characteristic that the retroreflective means of the present invention can be controlled independently for each sensor unit. It is good also as composition to do. FIG. 8 is a diagram partially showing the state of the retroreflective surface in the depth direction perpendicular to the input region, particularly with respect to the long-side region A of the basic configuration shown in FIG. It is. A retroreflective surface related to a sensor unit 2001R (not shown), and the retroreflective surface B arranged so as not to be retroreflected with respect to the sensor unit 2001L is actually recursive as shown in the figure. The retroreflective material mounting part B1 having a function of performing reflection and the retroreflective material non-mounting part B2 having no function of performing retroreflective without mounting the retroreflective material. Assuming that the area ratio of B1 and B2 to the surface B is 2: 3, in this configuration, the amount of light detected is 40% of the amount of light that is originally retroreflected by the entire surface B of the retroreflective means and received by the sensor unit 2001R. It becomes. Further, the area ratio of the effective retroreflective means is increased from the region A to the region C. As described above, the original region A has a large detection light amount level because the distance to the sensor unit 2001R is short and the incident angle is small, but the incident angle is increased by tilting the retroreflective surface. By controlling the area of retroreflecting effectively with the configuration of the retroreflecting surface in other embodiments, the maximum light quantity can be suppressed more effectively independently for each sensor unit, and the difference in the detected light quantity level distribution can be reduced. Can do. Of course, the same applies to the structure of the retroreflective surface in the region C with respect to the sensor unit 2001L. In addition, the effective retroreflective surface ratio, regardless of the above ratio, considers the aspect ratio of the apparatus, that is, the coordinate input surface, the inclination angle of the retroreflective surface in the embodiment, and further in the second embodiment, That is, an area ratio that can reduce the size difference in the detected light amount level distribution most according to the incident angle control related to retroreflection may be applied.

  Furthermore, the area control of the effective retroreflective surface may be performed in parallel with respect to the surface G related to the retroreflection of the sensor unit 2001L with respect to the region A in FIG. Specifically, on the surface G of the region A, contrary to the case of the surface B, the ratio of the effective retroreflective surface is 100%, and the sensor unit 2001L adjacent to the surface G is related to the retroreflection as it goes to the region C. Decrease the ratio of the surface sequentially. In this case as well, as in the case of the surface B, it is desirable to perform optimal area control in the entire detected light amount level distribution.

  In addition, as a method for controlling the effective retroreflective surface, the entire area in the field of view of the target sensor unit as shown in FIG. A configuration in which the effective surface is finely dispersed over the entire surface may be used, or a method such as making a hole in the surface or printing a mask in order to obtain a desired effective area ratio may be used.

The above shows a configuration in which a plurality of retroreflective surfaces on the long side are set to various inclination angles and areas. However, the fifth embodiment has a simpler configuration, particularly for a diagonal sensor unit. FIG. 9 shows a configuration for the purpose of improving the detected light amount distribution only at the corners of the long side where the reflected light amount is minimum. The basic configuration in which the retroreflective material is provided in the periphery is the same as that of the above embodiment, but as shown in the figure, the retroreflective material at both ends of the long side with respect to L indicating the position of the original long side retroreflective material. The position of the material is lowered by a certain distance as shown by M1 and M2 in the figure, and is arranged from the corner area A to the area A1. A to A1 are configured as a retroreflective surface on the extension of the conventional short side DA, but the length from A to A1 is A2 of the opening A-A2 resulting from lowering the retroreflective surface. The extension line from the diagonal sensor unit 2001L is set to A1. Alternatively, A1 is set at a lower position than the position of the extension line with some margin. With this retroreflective material configuration, the light beam incident on the retroreflective surface at the position of A-A2 on the long side conventionally enters the surface of AA1 on the short side. It does not enter M1, that is, A1-A3 parallel to the conventional retroreflective surface. Thereby, the incident angle ∠N shown in the typical figure of the light beam incident on the conventional A-A2 becomes the retroreflected light having the incident angle ∠O on the short side, and this retroreflected light has the aspect ratio of the present embodiment. In the case of the shape of the coordinate input device attached to the display device of ∠N> ∠O
Therefore, the incident angle is reduced, and therefore the retroreflectance is improved, the detected light amount in the region where the detected light amount is conventionally minimized is increased, and the detected light amount distribution as a whole is improved.

  Further, the light beam projected from the sensor unit 2001L to the area A2 ′ on the left side of A2 in the drawing cannot enter the retroreflective surface M1 in the direction indicated by the dotted line arrow and is retroreflected at the point A2 ′. The That is, since this portion is a portion where the amount of light to be detected is larger than that of the region A, the configuration is the same as the conventional detected light amount. Further, if this is not the configuration of the present invention, the central portion of the long side is also lowered uniformly to A1 and C1, and the space below the central portion cannot be used for other purposes. In addition, the light beam projected from the sensor unit 2001L to the region A2 'on the left side of A2 in the drawing is retroreflected on the surface of M1 at the same incident angle as that when retroreflected at the point A2'. The configuration of the present invention that retroreflects with ′ has an effect that the detected light quantity increases because the distance is shorter.

  Note that the position of A3 of A1-A3 constituting the retroreflective surface M1 is related only to the sensor unit 2001R with respect to the retroreflective surface M1, so that A3 comes on an extension line from the sensor unit 2001R to the point A2. Alternatively, A3 is set at a position further left than the position of the extension line with some margin.

  Although the configuration of the present embodiment in the vicinity of the region A has been described above, similarly for the region C, C1 and C3 are similarly set for the opening C-C2 in consideration of replacing the target sensor unit. The

  Since the lower part of A2-C2 is the position of the conventional retroreflective surface, a space for installing the control / arithmetic unit necessary for the apparatus or a control circuit for the necessary display device is provided below the part. Can be secured. The larger the required size of A-A2 and C-C2, the greater the effect of increasing the detected light amount. However, if the retroreflecting surface is lowered to the lower part of the central part of the long side, the space of the central part is reduced. It is desirable to adjust the structure in the entire apparatus.

  The fifth embodiment described above is different from the conventional configuration in which the step of the retroreflective means is simply provided in the corner region, and the retroreflective surfaces M1 and M2 lowered by one step shown in the figure are independent of only one sensor unit. The retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means is constituted by a retroreflective surface and is the basic idea of the present invention. In contrast, the arrangement of the retroreflective surfaces related to the light projecting means and the light receiving means is not shared, and the arrangement can be implemented with a simple configuration, particularly as a countermeasure for the minimum detected light quantity at the corners. An accurate coordinate input device can be realized. In addition, by using this configuration at both ends of the long side that is most required and in the vicinity thereof, the retroreflecting surface of the entire long side extends downward from the position of A to A1, compared to the lower part of the center of the long side. Space can be used effectively and the entire device can be made compact.

  Similarly to the above-described embodiment, in order to reduce the maximum detected light amount, M1 which is the retroreflective surface related to the sensor unit 2001R alone and M2 which is the retroreflective surface related to the sensor unit 2001L alone are inclined. Thus, the incident angle may be increased, or the effective retroreflective surface may be controlled to reduce the difference in the detected light amount as a whole, thereby improving the dynamic range.

<Description of Control / Calculation Unit 2002>
A control signal of the line CCD 41, a CCD clock signal, an output signal of the line CCD 41, and a drive signal of the LED 31 are exchanged between the control / arithmetic unit 2002 and the sensor units 2001L and 2001R in FIG.

  FIG. 10 is a block diagram showing the configuration of the control / arithmetic unit 2002, in which 2001L and 2001R are sensor units, 81L and 81R are A / D converters, 82 is a memory, 83 is a one-chip microcomputer, and the like. The CPU (central processing unit), 84L and 84R are LED drive circuits, 85 is an operation clock for CPU control, 86 is an operation clock (CLK) for CCD control, and 87 is a serial interface.

  In FIG. 10, a CCD control signal is output from the CPU 83, and performs shutter timing of the line CCD 41, data output control, and the like. The clock for the line CCD 41 is sent from the CLK 86 to the sensor units 2001L and 2001R, and is also input to the CPU 83 in order to perform various controls in synchronization with the line CCD 41.

  The LED drive signal is supplied from the CPU 83 to the infrared LEDs 31 in the sensor units 2001L and 2001R via the LED drive circuits 84L and 84R.

  Detection signals from the line CCD 41 serving as detection means in the sensor units 2001L and 2001R are input to the A / D converters 81L and 81R in the control / arithmetic unit 2002, and converted into digital values under the control of the CPU 83. The converted digital value is stored in the memory 82 as necessary, and an angle is calculated and a coordinate value is obtained by a method described later. The result is sent to an external PC (personal computer) or the like via the serial interface 87 or the like. Is output.

<Explanation of light intensity distribution detection>
FIG. 11 is a timing chart of control signals. In FIG. 11, reference numerals 91, 92, and 93 denote control signals for controlling the line CCD 41, and the shutter release time of the line CCD 41 is determined at intervals of 91Sh signals. Reference numerals 92 and 93 denote gate signals to the left and right sensor units 2001L and 2001R, respectively.

  94 and 95 are drive signals for the LEDs 31 of the left and right sensor units 2001L and 2001R. In order to light one LED 31 (in this case, the LED in the sensor unit 2001L) in the first cycle of Sh, The LED 31 is supplied to the LED 31 via the LED driving circuit (in this case, the LED driving circuit 84L). The other LED (in this case, the LED in the sensor unit 2001R) is driven in the next cycle. After the driving of both LEDs 31 is completed, the signal of the line CCD 41 is read from the left and right sensor units 2001L and 2001R.

  For example, when there is no input by a finger or an indicator, that is, when there is no light shielding part, the read signal is output as the output from each of the sensor units 2001L and 2001R as shown in FIG. Distribution is obtained.

  FIG. 12 is a diagram showing the relationship between the output level (V) of the line CCD 41 and the CCD pixel number [N], in which the vertical axis represents the output level (V) of the line CCD 41 and the horizontal axis represents the CCD pixel. Number [N] is shown respectively.

  Of course, such a light quantity distribution is not necessarily obtained in any system. The characteristics of the retroreflective means 2004 (retroreflective characteristics depending on the incident angle of the retroreflective means 2004 described above), the characteristics of the light projecting means 30 including the LED 31, Further, this light amount distribution changes due to a change with time (dirt of the reflection surface of the retroreflective means 2004, etc.).

  In FIG. 12A, it is assumed that the level A is the level when the maximum light amount is detected, and the level B is the minimum level. Therefore, the level obtained in the absence of reflected light is near B. As the amount of reflected light increases, the level of A approaches. As described above, the data output from the line CCD 41 is sequentially A / D converted by the A / D converter and then taken into the CPU 83 as digital data.

  FIG. 12B is a diagram showing an example of output when input is performed with a finger or the like, that is, when the reflected light of the retroreflective means 2004 is blocked, and part C of FIG. Since the reflected light of the means 2004 is blocked, the amount of light only at that portion is reduced.

  The detection of the light amount distribution is performed by detecting the change in the light amount distribution. More specifically, the light amount distribution is detected first in an initial state without input as shown in FIG. Are stored in the memory 82 in advance, and the difference between the data obtained in each sample period and the initial data stored in the memory 82 is calculated. It is determined whether or not there is a change such as 12 (B).

<Description of angle calculation>
In calculating the angle, it is first necessary to detect the light shielding range.

  As described above, since the light quantity distribution is not constant due to changes over time, it is desirable to store the above-mentioned initial data when the system is started up. That is, if initial data is set at the time of shipment from a factory or the like and the data is not updated sequentially, for example, when dust adheres to the reflective surface of the retroreflective means 2004 at a predetermined position, retroreflection at that portion is performed. Since the efficiency is lowered, the saddle also causes a serious result that the coordinate input operation is performed at that position (direction seen from the sensor units 2001L and 2001R), that is, erroneous detection is performed. Therefore, by storing the above-mentioned initial data at the time of starting the system, even if the reflection surface of the retroreflective means 2004 becomes dirty with dust or the like with time and the retroreflective efficiency is lowered, the state is set as the initial state. Since it can be redone, malfunctions can be eliminated.

  Of course, if the signal from the retroreflective means 2004 cannot be received at the part where the dust is attached, it becomes impossible to detect the coordinates and the dust must be removed by some method. In a state where the optical signal from the means 2004 is greatly reduced, the reliability of the signal is reduced due to the S / N ratio (for example, the phenomenon that the coordinates fluctuate despite the fact that the same point is indicated). Even if this is the case, it is preferable to remove the attached dust and the like, and in the present invention, it is possible to easily remove the dust and the like. Thus, a light transmission member 1001 is provided.

  Now, when the power is turned on, the output of the line CCD 41 is first A / D converted by the A / D converters 81L and 81R without illuminating from the light projecting means 30 without any input (no light-shielding portion). This is stored in the memory 82 as Bas_data [N]. This is data including variations in the bias of the line CCD 41 and the like, and is data near the level B in FIG. Here, [N] is a CCD pixel number, and a pixel number corresponding to an effective input range is used.

  Next, the light quantity distribution in the state illuminated from the light projecting means 30 is stored. The data is represented by a solid line in FIG. 12A, and is set as Ref_data [N], and the storage of the initial data is completed.

  Using these data, it is first determined whether an input has been made or whether there is a light shielding range.

  Data of a certain sample period is assumed to be Norm_data [N].

  First, in order to specify the light shielding range, the presence / absence of input is determined based on the absolute amount of change in data. This is to prevent erroneous determination due to noise or the like and to detect a certain amount of reliable change. The absolute amount of change is calculated for each pixel by the following equation (1) and compared with a predetermined threshold value Vtha.

Norm_data_a [N] = Norm_data [N] −Ref_data [N] (1)
Therefore, Norm_data_a [N] corresponds to the absolute change amount in each pixel.

  Since this process only compares the differences, the processing time can be shortened, so that the presence / absence of input can be determined at high speed.

  When the number of pixels exceeding Vtha for the first time is detected exceeding a predetermined number, it is determined that there is an input.

  Next, in order to detect with higher accuracy, a change ratio is calculated to determine an input point.

  FIG. 13 is a diagram showing a retroreflective surface of the retroreflective means 2004. In FIG. 13, reference numeral 910 denotes a reflective surface of the retroreflective means 2004, and 911 denotes an instruction means such as a finger or an indicator. Here, assuming that the reflectance of the region (10) of the reflecting surface 910 is reduced due to dirt or the like, the distribution of Ref_data [N] at this time is as follows. Less.

  FIG. 14 is a diagram showing the relationship between the output level (V) of the line CCD 41 and the CCD pixel number [N], in which the vertical axis indicates the output level (V) of the line CCD 41 and the horizontal axis indicates the CCD pixel. Number [N] is shown respectively.

  In the state shown in FIG. 14A, if almost half of the retroreflective means 2004 is covered by the pointing means 911 such as a finger or pointing tool as shown in FIG. ) Distribution Norm_data [N] indicated by a thick line is observed. When the above formula (1) is applied to this state, the result is as shown in FIG.

  FIG. 15A is a diagram showing the relationship between Norm_data_a [N] and the CCD pixel number [N]. In FIG. 15A, the vertical axis indicates Norm_data_a [N], and the horizontal axis indicates the CCD pixel number [N]. , Respectively.

  FIG. 15B is a diagram showing the relationship between Norm_data_r [N] and the CCD pixel number [N]. In FIG. 15B, the vertical axis indicates Norm_data_r [N], and the horizontal axis indicates the CCD pixel number [N]. ] Are shown respectively.

  Here, in FIG. 15, the vertical axis represents the differential voltage from the initial state.

  When this data is compared with the threshold value Vtha, there is a case where the original input range is deviated (broken line area in FIG. 15A). Of course, by setting the threshold value Vtha to a smaller value, a certain degree of detection is possible, but the possibility of being affected by noise or the like is increased, resulting in a problem that the coordinate calculation performance is degraded.

  Therefore, the amount of light blocked by the instruction means 911 is the first half of the area (10) and the area (11) of the reflecting surface 910 (corresponding to the V1 level in the area (10) and equivalent to the level V2 in the area (11)). Then, the change ratio is calculated by the following equation (2).

Norm_data_r [N] = Norm_data_a [N] / (Bas_data [N] -Ref_data [N]) (2)
The calculation result of this equation (2) is as shown in FIG. 15B and is represented by a fluctuation ratio, so that even when the reflectance is different, it can be handled equally. By separately setting the threshold value Vthr, pixel information can be obtained with high accuracy from the pixel numbers of the rising and falling portions, for example, using the center of both as the input pixel.

  Incidentally, FIG. 15B is schematically drawn for convenience of explanation, and FIG. 16 shows an actual detection signal waveform in detail.

  Now, it is assumed that the rising portion of the light-shielding region as compared with the threshold value Vthr exceeds the threshold value Vthr in the Nfth pixel, assuming that the Nrth pixel exceeds the threshold value Vthr. At this time, as described above, the pixel number Np of the line CCD 41 to be output may be calculated as the median value of the pixel numbers of the rising and falling portions as shown in the following formula (3). The pixel interval of the line CCD 41 becomes the resolution of the output pixel number.

Np = Nr + (Nf-Nr) / 2 (3)
Therefore, in order to detect with higher resolution, calculation is performed using the output level information of the pixel.
In FIG. 16, the output level of the line CCD 41 with the pixel number Nr is Lr, and the output level of the pixel number Nr-1 is Lr-1. Similarly, the output level of the pixel number Nf is Lf, and the output level of the pixel number Nf-1 is Lf-1. If the pixel numbers to be detected at this time are Nrv and Nfv respectively,
Nrv = Nr-1 + (Vthr-Lr-1) / (Lr-Lr-1) (4)
Nfv = Nf-1 + (Vthr-Lf-1) / (Lf-Lf-1) (5)
Is calculated, a virtual pixel number corresponding to the output level, that is, a pixel number smaller than the pixel number of the line CCD 41 can be acquired, and the virtual center pixel Npv to be output is determined by the following equation (6).

Npv = Nrv + (Nfv-Nrv) / 2 (6)
As described above, by calculating the virtual pixel number from the pixel number and the output level of the pixel, detection with higher resolution becomes possible.

<Conversion from CCD pixel information to angle information>
Now, in order to calculate an actual coordinate value from the obtained center pixel number, it is necessary to convert the aforementioned pixel number into angle information.

FIG. 5 is a graph plotting the relationship between the obtained pixel number and the angle θ. Approximate expression of this relationship (Formula 7 below)
θ = f (N) (7)
The data is converted from this approximate expression.

  In the present invention, the lens group of the light receiving means in the sensor units 2001L and 2001R described above is configured so that it can be approximated using a first-order approximation formula. However, higher-order approximation is performed due to optical aberration of the lens and the like. In some cases, the angle information can be obtained with higher accuracy by using the equation.

  The lens group to be used is closely related to the manufacturing cost, and optical distortion generally generated by lowering the manufacturing cost of the lens group is corrected using a higher-order approximation formula. In such a case, since a certain amount of computing power (calculation speed) is required, both may be set as appropriate in consideration of the coordinate calculation accuracy required for the target product.

<Description of coordinate calculation method>
FIG. 17 is a diagram showing the positional relationship between the sensor unit 2001L and the sensor unit 2001R in the coordinate input device according to the present embodiment. The horizontal direction of the coordinate input effective area 2003 is the X axis, the vertical direction is the Y axis, and The center of the coordinate input effective area 2003 is arranged at the origin position, the sensor unit 2001L and the sensor unit 2001R are mounted symmetrically with respect to the Y axis on the left and right sides of the coordinate input effective area 2003, and between the sensor units 2001L and 2001R. Let Ds be the distance.

  Further, as shown in the drawing, the light receiving surfaces of the line CCD 41 of the sensor units 2001L and 2001R are arranged so that the normal direction forms an angle of 45 ° with the X axis, and the normal direction is 0 ° (reference Direction). At this time, the sign of the angle is the clockwise direction in the case of the sensor unit 2001L arranged on the left side, and the counterclockwise direction in the case of the sensor unit 2001R arranged on the right side. The direction of is defined as the “+” direction.

  Furthermore, Po in the figure is the position of the intersection of the sensor units 2001L and 2001R in the normal direction, and the distance from the origin in the Y-axis direction is defined as Poy. At this time, the angles P obtained by the respective sensor units 2001L and 2001R are θL and θR, and the coordinates P (x, y) of the point P to be detected are obtained by the following equations (8) and (9).

次に、本実施の形態に係る座標入力装置の一連の処理工程を、図１８を用いて説明する。

Next, a series of processing steps of the coordinate input device according to the present embodiment will be described with reference to FIG.

  FIG. 18 is a flowchart showing a flow of processing operations from data acquisition to coordinate calculation of the coordinate input device according to the present embodiment.

  When the power is turned on, first, in step S1801, various initializations such as port settings for the CPU 83, timer settings, and the like are performed. Next, in step S1802, the effective range of a CCD pixel, which is a light receiving element described later, is read from, for example, the memory 82 and set. In step S1803, the number of initial readings, which is a preparation for removing unnecessary charges of the line CCD 41 that is performed only at startup, is set.

  In photoelectric conversion elements such as the line CCD 41, unnecessary charges may be accumulated when not being operated, and if the data is used as it is as reference data, it may become undetectable or cause false detection.

  In order to avoid this, in step S1804, the data from the line CCD 41 is stored in the line CCD 41 by reading the number of times set in advance in the step S1801 in a state where the light projecting means 30 is not illuminated. Unnecessary charges are removed.

  In step S1805, it is determined whether the number of readings has reached a predetermined number. If it is determined that the number of readings has not reached the predetermined number, the process returns to step S1804. If it is determined that the number of readings has reached the predetermined number, the process proceeds to step S1806.

  In step S1806, data is acquired when the light projecting unit 30 is not illuminated. This corresponds to the acquisition of Bas_data [N] described above as reference data. In step S1807, the data is acquired in step S1806. The obtained data is stored in the memory 82 and used for subsequent calculations.

  Next, in step S1808, reference data Ref_data [N] corresponding to the initial light quantity distribution when illuminated by the light projecting means 30 is fetched. In the next step S1809, the data acquired in step S1808 is stored in the memory 82. Remember.

  Up to the above steps is the initial setting operation when the power is turned on, but it goes without saying that this initial setting operation may be configured to operate according to the operator's intention using a reset switch or the like. After that, the normal capturing operation state is entered.

  In the normal capturing operation, first, in step S1810, the light amount distribution is captured by normal capturing. Next, in step S1811, a difference value with respect to the memory data (Ref_data) is calculated, and in the next step S1812, it is determined whether or not there is a light shielding portion, that is, whether or not there is a coordinate input. If it is determined that there is no coordinate input, the process returns to step S1810 to similarly start data acquisition.

  On the other hand, if it is determined in step S1812 that there is a coordinate input, the process proceeds to step S1813, and the ratio with the memory data is calculated using the equation (2). Next, in step S1814, a rising portion and a falling portion are determined by a threshold with respect to the ratio obtained in step S1813, and a pixel number is calculated by the above equations (4), (6), and (7).

  Next, in step S1815, for example, Tanθ is calculated from the pixel number obtained in step S1814 from an approximate polynomial, and in the next step S1816, x, y are calculated from the Tanθ values in the left and right sensor units 2001L and 2001R. The coordinates are calculated using the equations (8) and (9). In step S1817, the data calculated in step S1816 is transmitted to an external device such as a host PC. The data transmission means may be transmitted by any interface such as serial communication such as USB, RS232C, etc. After the transmission process of step S1817 is completed, the process returns to the process of step S1810 and thereafter the power is turned off or This process is repeated until the reset state is set according to the operator's intention.

  If this repetition cycle is set to about 10 [msec], the coordinate input device according to the present embodiment can display the coordinates designated by the pointing means 911 such as a finger or pointing tool at a cycle of 100 times / second to an external device or the like. It becomes possible to output.

  As described above, according to the coordinate input device according to the present embodiment, the difference between the maximum light amount and the minimum light amount of the detection signal waveform can be reduced, so that the coordinate calculation resolution of the coordinate input device is greatly improved. Can be made.

(Other embodiments)
The above is the description of the embodiments of the present invention. However, the present invention is not limited to these embodiments, and the functions shown in the claims or the functions of the embodiments can be achieved. Any configuration is applicable.

It is a schematic block diagram of the coordinate input device which concerns on 1st Embodiment. It is a disassembled perspective view of the sensor unit in the coordinate input device which concerns on 1st Embodiment. It is an external view of the sensor unit in the coordinate input device which concerns on 1st Embodiment. It is explanatory drawing of the detection means in the sensor unit in the coordinate input device which concerns on 1st Embodiment. It is a figure which shows the relationship between the pixel number N and angle (theta) in the coordinate input device which concerns on 1st Embodiment. It is a figure which shows the detection level in the coordinate input device which concerns on 1st Embodiment. (A)-(B) It is a figure which shows schematic structure and the detection level of the retroreflection means in the coordinate input device which concerns on 2nd Embodiment. (C)-(E) It is a figure which shows schematic structure and the detection level of the retroreflection means in the coordinate input device which concerns on 3rd Embodiment. It is a figure which shows schematic structure of the retroreflection means in the coordinate input device which concerns on 4th Embodiment. It is a schematic block diagram of the coordinate input device which concerns on 5th Embodiment. It is a block diagram which shows the structure of the control and arithmetic unit in the coordinate input device which concerns on 1st Embodiment. It is a timing chart of light emission of the light projection means in the coordinate input device according to the first embodiment. It is a figure which shows an example of the light quantity distribution of the light projection means in the coordinate input device which concerns on 1st Embodiment. It is a figure which shows an example of the time-dependent change of the reflective surface of the retroreflection means in the coordinate input device which concerns on 1st Embodiment. It is explanatory drawing of the light quantity change in the coordinate input device which concerns on 1st Embodiment. It is explanatory drawing of the light quantity change amount and light quantity change rate in the coordinate input device which concerns on 1st Embodiment. It is explanatory drawing of the light-shielding range detection in the coordinate input device which concerns on 1st Embodiment. It is explanatory drawing of the coordinate calculation in the coordinate input device which concerns on 1st Embodiment. It is a flowchart which shows the flow of the coordinate detection process operation | movement in the coordinate input device which concerns on 1st Embodiment. It is operation | movement explanatory drawing in the conventional coordinate input device. It is explanatory drawing of the detection signal level in the conventional coordinate input device. It is a figure which shows the relationship between the detection signal level and CCD pixel number in the conventional coordinate input device. It is explanatory drawing of the light projection means in the conventional coordinate input device. It is a figure which shows the relationship between the light projection level of the light projection means in a conventional coordinate input device, and an angle. It is explanatory drawing of the retroreflection means in the conventional coordinate input device. It is a characteristic view of the retroreflection means in the conventional coordinate input device.

Explanation of symbols

1001 Light transmitting member 2001L Sensor unit 2001R Sensor unit 2002 Control / arithmetic unit (setting unit)
2003 Coordinate input effective area 2004 Retroreflective means 2005 Instruction means (light-shielding member)
30 Projection means 31 Infrared LED (light emitting diode)
32 Projection lens 40 Light receiving means (detection means)
41 line CCD

Claims (3)

  To the retroreflective means for retroreflecting incident light installed on the three sides around the rectangular coordinate input area and the retroreflective means provided in the vicinity of both corners of one side where the retroreflective means is not installed A light projecting unit configured to project a light beam, and a light receiving unit configured to receive the light beam retroreflected by the retroreflecting unit, and the light beam projected by the light projecting unit is blocked by the instruction unit. A coordinate input device that calculates a position coordinate of a light-shielding portion by the instruction means based on a change in a light amount distribution obtained from a light receiving means, wherein the retroreflective means on the opposite side of the non-retroreflective means is provided by a plurality of retroreflective surfaces. The retroreflective surface related to the incidence and reflection of one of the light projecting means and the light receiving means is connected to the other light projecting means and light receiving means in all or part of the retroreflective surface of the apparatus. Unlike Waru retroreflective surface, the coordinate input device, wherein the retroreflective surfaces according to the light projecting means and said light receiving means with each other are arranged so as to be non-covalent.   In the retroreflective surface related to the light projecting unit and the light receiving unit, the incident angle of the light beam to the retroreflective surface having a large distance to the light projecting unit and the light receiving unit is small. The coordinate input device according to claim 1, wherein the retroreflective surface is disposed so as to be smaller than an incident angle of the light beam on the retroreflective surface.   In the retroreflective surface related to the light projecting unit and the light receiving unit, the effective retroreflective area of the retroreflective surface having a large distance to the light projecting unit and the light receiving unit has a small recursion to the light projecting unit and the light receiving unit. The coordinate input device according to claim 1, wherein the retroreflective surface is configured to be larger than an effective retroreflective area of the reflective surface.

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