JP2005346230A - Optical digitizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical digitizer capable of detecting a pen-down from both retroreflected light from a retroreflective member provided to a contact pen shaft atop of the pen at a distance from the pen tip and a light shield part at its periphery. <P>SOLUTION: The retroreflective member is mounted above the surface of the pen tip which comes into contact with an input surface within a range having its lower limit in a retroreflective plate mount area of a peripheral frame and its upper limit outside the mount area (upper part) to add pen reflected light information which is sensitive to pen-down behavior to light shield shadow information which is insensitive at a lower part within the retroreflective plate mount area, thereby detecting the pen being put down. More specifically, when the ratio of a light shield level and a retroreflected light level exceeds a certain threshold, the pen-down behavior is detected. Alternatively, the pen-down behavior is detected from temporal variation in quantity of light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coordinate input device, and more specifically, coordinates used to control a connected computer or to write characters, figures, etc. by inputting coordinates by pointing to an input surface with an indicator or a finger. The present invention relates to a technology for improving the performance of an input device.

  In particular, in the present invention, a retroreflective material is provided around the input surface, and further, a retroreflective material is provided on the pointing tool, and the indicated position coordinates are input by detecting the light shielding state by the pointing tool and the retroreflected light from the pointing tool. The present invention relates to a retroreflected light shielding type coordinate input device.

  Conventionally, as this type of device, various types of touch panels have been proposed or commercialized, and it is widely used because it is easy to operate a PC on the screen without using special equipment. It has been.

  There are various methods such as a method using a resistance film and a method using ultrasonic waves. As shown in Patent Document 1 as a method using light, the method recurs outside the coordinate input surface. In the configuration in which a reflective sheet is provided, the light from the means for illuminating the light is reflected by the retroreflective sheet, and the light distribution is detected by the light receiving means, the angle of the area within the input area that is shielded by a finger or the like is detected However, it is known to determine the coordinates of the shielding position, that is, the input position.

  Further, as in Japanese Patents Nos. 2 and 3, the retroreflective member is configured around the input region, and a device for detecting the coordinates of the portion where the retroreflected light is shielded is disclosed. .

  In these apparatuses, for example, in Patent Document 2, the angle of the light-shielding part is detected by detecting the peak of the light-shielding part by waveform processing calculation such as differentiation, and in Patent Document 3, comparison with a specific level pattern is performed. Shows a configuration in which one end and the other end of the light shielding portion are detected and the center of the coordinates is detected.

  Further, in Patent Document 1, when each pixel of the RAM imager is read and compared by a comparator, a light-shielding portion is detected, and when there is a light-shielding portion having a certain width or more, the centers of the pixels at both ends thereof are detected. A detection method for detecting (1/2 position) is shown.

On the other hand, Patent Document 4 discloses an apparatus that detects an angle by detecting reflected light from a reflective cursor and detects the coordinates of the cursor.
U.S. Pat.No. 4,507,557 Japanese Unexamined Patent Publication No. 2000-105671 JP 2001-1472642 A JP-A-3-5805

  In the conventional method of blocking retroreflected light from the peripheral frame retroreflecting material provided around the input surface with an indicator or a finger, the detected light amount change due to a simple shading shadow is detected. Although various attempts have been made to increase the level, there are limits to the level, and it has been difficult to increase the accuracy of coordinate detection. In addition, a part of the hand holding the pointing device may be shielded from light during input, resulting in erroneous detection due to a hand. Further, in terms of function, as a characteristic of the light-shielding method, it was originally possible to input coordinates by using a finger or the like in addition to a pen-like pointing tool without selecting a pointing tool. It is difficult to identify whether the input is input, and for example, it is impossible to switch between the pending timing and the application depending on the input method. In the same conventional optical coordinate input method that detects reflected light from an indicator, the amount of increase in the amount of light is simply detected, so the detection accuracy is limited. In this method, In addition, it was impossible to give instructions with fingers other than wearing a special sack.

  On the other hand, in the conventional method for detecting the light shielding portion, the light to be shielded has a certain width substantially equal to the width of the peripheral frame retroreflective member in the direction perpendicular to the input surface. In this case, there is not much problem. However, when characters or the like are input with the pointing tool (pen), the timing of pen-up and pen-down becomes insensitive and the problem of tailing occurs. In order to solve this, an indicator (pen) tip switch means is provided by a commercially available tact switch or the like, which is a known technique that switches sensitively by contact with the input surface at the tip of the indicator, and this indicator (pen) It is conceivable to take the timing of pen up and down based on the previous switch signal. However, when the indicator (pen) tip switch is provided, a means for transmitting the switch information to the coordinate calculation control circuit on the main body side is necessary. For this purpose, the indicator (pen) has a power source (battery). ), And it is necessary to provide transmission means such as infrared rays, radio waves, or ultrasonic waves, so that the indicator (pen) becomes larger and heavier and the reception means is required on the main body side. was there.

In the present invention, in order to solve the above problems, a plurality of light receiving detection means are provided at the corners of the coordinate input area surface,
A peripheral frame retroreflecting means that recursively reflects incident light provided around the coordinate input area surface, and a light projecting means that projects light onto the peripheral frame retroreflecting means;
An angle detection unit for detecting a direction instructed by an indicator or the like from a change in the amount of light from the light projecting unit reflected by the peripheral frame retroreflecting unit detected by the light receiving detection unit; An optical coordinate input device that calculates position coordinates on a coordinate input area surface designated by the pointing device based on angle information,
The indicator includes a light shielding unit that shields reflected light from the peripheral frame retroreflecting unit, and the light projecting unit within the detection range of the light receiving detection unit when the tip of the indicator contacts the coordinate input area surface. The pointing tool retroreflecting portion for retroreflecting the light is further provided, and the mounting position of the pointing tool retroreflecting portion from the tip of the pointing tool is the mounting position from the coordinate input area surface of the peripheral frame retroreflecting means. The range is a range from a position longer (separated) than the shortest distance to a position longer (separated) than the longest distance. According to the configuration of the pointing tool of the present invention, it is possible to simultaneously obtain a light amount distribution by a light shielding shadow by the pointing tool or the like and retroreflected light by the pointing tool retroreflective member with a simple configuration. Compared to the case where the light-shielding shadow by the conventional pointing tool or the like, or the retro-reflected light by the pointing tool retro-reflecting member is detected alone, the two light quantity change information of the retro-reflected light and the light-shielding shadow in the pointing tool of the present invention. By detecting the indicated position, the coordinate detection accuracy can be further improved. Furthermore, by distinguishing it from simple shading shadows due to the handle, the influence of the handle can be eliminated. By calculating the ratio of the light amount of retroreflected light by the reflecting portion and the light amount of the light shielding shadow by the light shielding portion of the pointing tool, the contact state on the coordinate input area surface can be detected by the change in the ratio. An indicator having a simple structure can be realized without providing a power source.

  As described above, in the present invention, the peripheral frame retroreflecting means is provided at the corner of the coordinate input area surface, and is provided at the periphery of the coordinate input area surface to recurs the incident light. A light projecting means for projecting light onto the peripheral frame retroreflecting means, and a change in the amount of light from the light projecting means reflected by the peripheral frame retroreflecting means detected by the light receiving detection means. An optical coordinate input device that has an angle detection means for detecting the direction indicated by the etc., and calculates the position coordinates on the coordinate input area surface indicated by the indicator etc. based on the derived plurality of angle information. Then, the indicator has a light-shielding part that shields the reflected light from the peripheral frame retroreflecting unit, and the light projection within the detection range of the light receiving detector when the tip of the indicator contacts the coordinate input area surface. An indicator retroreflecting part that retroreflects the light from the means is installed. Furthermore, the mounting position of the pointing tool retroreflective portion from the tip of the pointing tool is longer than the shortest distance of the mounting position from the coordinate input area surface of the peripheral frame retroreflective means, and the longest distance from the position. It was set as the structure which is a range over the position longer (separated) than distance. According to the configuration of the pointing tool of the present invention, it is possible to simultaneously obtain a light amount distribution by a light shielding shadow by the pointing tool or the like and retroreflected light by the pointing tool retroreflective member with a simple configuration. Compared to the case where the light-shielding shadow by the conventional pointing tool or the like, or the retro-reflected light by the pointing tool retro-reflecting member is detected alone, the two light quantity change information of the retro-reflected light and the light-shielding shadow in the pointing tool of the present invention. By detecting the indicated position, the coordinate detection accuracy can be further improved. Further, by distinguishing from a simple shading shadow due to the hand, the influence of the hand can be eliminated. Further, by calculating the ratio of the light amount of retroreflected light by the pointing tool retroreflecting portion and the light amount of the light shielding shadow by the light shielding portion of the pointing tool, the contact state to the coordinate input area surface can be detected by the change of this ratio. I can do it. This is because the conventional detection of only the shading shadow cannot detect the movement of the tip of the pointing tool outside the reach of the retroreflected light from the peripheral frame retroreflective member near the coordinate input surface. In this invention, the retroreflective member reacts sensitively to movement in the vicinity of the coordinate input surface by providing the retroreflective member within the projection range from the projection means within the peripheral frame retroreflective means mounting range. . Furthermore, with the configuration of the present invention, an indicator having a simple structure can be realized without providing a power source to the indicator itself. In particular, the tip portion of the characteristic indicator of the present invention has a simple configuration, high industrial feasibility, and at the same time high reliability.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
A schematic configuration of a coordinate input device according to the present invention will be described with reference to FIG.

  In the figure, reference numerals 1L and 1R denote sensor units each having a light projecting unit and a light receiving detection unit, and are installed at a predetermined distance. The sensor unit is connected to a control / arithmetic unit 2 that performs control / calculation, receives a control signal from the control / arithmetic unit, and transmits a detected signal to the control / arithmetic unit. Reference numeral 3 denotes a peripheral frame retroreflective means having a retroreflective surface that reflects incident light in the direction of arrival as shown in FIG. 2, and the light projected from the left and right sensor units in a range of approximately 90 ° , Retroreflected toward the sensor unit. The reflected light is detected one-dimensionally by the detection means of the sensor unit constituted by a condensing optical system and a line CCD, and the light quantity distribution is sent to the control / arithmetic unit.

  Reference numeral 5 denotes a coordinate input surface, which includes a display screen 4 of a display device such as a PDP, a rear projector, an LCD panel, or a front plate 4 ′ (not shown) that is a substantially transparent plate disposed on the front surface of the display screen 4. Therefore, it can be used as an interactive input device.

  In such a configuration, when an input instruction is given to the input area with the pen-shaped pointing tool 6 shown in the figure, the light projected from the light projecting means is blocked and the peripheral frame retroreflecting means 3 Since the reflected light due to retroreflection cannot be obtained, the amount of light cannot be obtained only at the input instruction position. Furthermore, in the pointing tool 6 of the present invention, as shown in FIG. 1-2, in the tip member 6-1 at the tip portion of the pointing tool 6, the tip member 6-1 is its coordinate input surface. A pointing tool retroreflective portion 6-2 having retroreflective properties at a certain distance from the tip portion in contact with 5 is attached to the tip member 6-1. When the distal end portion of the indicator 6 enters the light beam range from the light projecting unit and the light beam range where the retroreflected light retroreflected by the peripheral frame retroreflecting unit 3 enters the light receiving detection unit, The pointing tool tip member 6-1 produces a light shielding shadow, and the pointing tool retroreflecting unit 6-2 generates retroreflected light. Details regarding the pointing tool 6 will be described later.

  The arithmetic control means of the main unit detects the light-shielding range of the input instructed part from the light quantity change of the left and right sensor units, specifies the detection point within the same range, and calculates the respective angles. The coordinate position on the input area is calculated from the calculated angle and the distance between the sensor units. Further, whether the tip member of the pointing tool 6 has contacted the coordinate input surface 5 or not, that is, a pen-up / pen-down state, is detected based on changes in the light-shielding light quantity distribution and the retroreflected light quantity distribution.

  In this way, the operation of the PC such as drawing a line on the screen, operating a switch, or an icon can be performed with the pointing tool or the like.

  Hereinafter, detailed description will be made for each part.

<Explanation on the distal end of the pointing tool as the main point of the present invention>
The general configuration of the pointing tool 6 in the present invention is as described above, but the detailed structure will be described with reference to FIGS. As described above, in a part of the tip member 6-1 having the light shielding property at the tip portion of the pointing tool 6, the tip member 6-1 is separated from the tip portion in contact with the coordinate input surface 5 by a certain distance. A pointing device retroreflective portion 6-2 having retroreflective properties is attached. In the present embodiment, for simplicity of explanation, the tip member 6-1 is substantially cylindrical except for a part of the tip. Accordingly, the pointing device retroreflective portion 6-2 attached to the tip member 6-1 is also arranged in a cylindrical shape. For example, a retroreflective layer having a bead structure is formed on the cylindrical side surface of the pointing tool retroreflective portion 6-2. This retroreflective layer with a bead structure is a bead layer made of glass beads, an aluminum deposited film at an approximate focal point of the lens effect of the bead, or an electrode coating such as silver, or other optical reflective properties. The reflective layer to be formed and a binder resin layer or the like for fixing them are formed so that light incident on the bead surface is reflected in substantially the same direction as the incident direction. These are generally commercially available as retroreflective tape, and may be formed into a cylindrical shape. The indicator retroreflecting portion 6-2 may be formed not only by a bead type but also by a prism or corner cube type.

  In the above embodiment, the tip member 6-1 and the pointing device retroreflecting portion 6-2 are formed in a cylindrical shape, but a sufficient thickness and shape are secured to detect the light-shielding portion as a change in the amount of light, If the retroreflectance of the pointing tool retroreflecting portion 6-2 is within an incident angle range that is ensured within a certain necessary range, the pointing tool 6 has a so-called pen shape, and the diameter becomes narrower toward the tip. The side shape of the truncated cone or other shapes may be used.

  With the configuration of the pointing tool 6 in the present invention, the light reflected by the peripheral frame retroreflecting means 3 is blocked by the tip member 6-1, and the light receiving detection means reduces the light amount or almost. It is detected as a shadow where the amount of light is not detected. The light reflected by the peripheral frame retroreflecting means 3 is also incident on the mounting area of the pointing device retroreflecting unit 6-2 mounted on the tip member 6-1, but this light is retroreflected again. Radiated toward the peripheral frame retroreflecting means 3, the amount of light is not detected by the light reception detecting means, and as a result, the mounting area of the pointing tool retroreflecting unit 6-2 is also from the peripheral frame retroreflecting means 3. The retroreflected light becomes a shading shadow. On the other hand, for the light from the light projecting means, only the pointing tool retroreflecting unit 6-2 emits retroreflected light to the light projecting means, and is disposed in the vicinity of the light projecting means. In the received light detecting means, the retroreflected light is detected. This is due to the retroreflective characteristic called the observation angle in the retroreflective characteristic of the pointing tool retroreflective section 6-2, and is the angle of deviation of the direction of the detection side from the direction of the incident light. Is the most efficient, but the retroreflected light can be detected sufficiently within a few degrees. The same applies to the case where the light receiving detection means detects retroreflected light from the light projecting means by the peripheral frame retroreflecting means 3. The retroreflected light from the pointing tool retroreflecting unit 6-2 reflects the retroreflective material as a characteristic of the retroreflective material. When the incident angle is small, sufficient retroreflected light is reflected in the incident direction. Decreases. Accordingly, sufficient retroreflected light is emitted in the vicinity of the axial center, but sufficient retroreflected light cannot be obtained in the peripheral portion away from the axial center. As described above, this is an important point of the present invention. In the state where the retroreflected light from the peripheral frame retroreflecting means 3 is present, when the light is shielded by an indicator having its own retroreflective characteristics, In addition to the light amount decrease portion due to the light shielding, a configuration in which the light amount increase portion due to the retroreflected light mainly from the vicinity of the center of the pointing tool itself is simultaneously detected. As a result, when the coordinate input area is indicated by the pointing tool 6 due to the structure of the tip of the pointing tool 6 of the present invention, the light quantity distribution detected by the sensor unit having the 1L and 1R detecting means is as follows. The light quantity distribution has a light quantity increase peak due to retroreflected light in the shading shadow. By using this light quantity distribution, it is possible to detect the pointing coordinates of the pointing tool or the state of contact with the coordinate input surface 5, that is, pen-down and pen-up.

Furthermore, it is desirable to define the position of the pointing tool retroreflective portion 6-2 attached to the tip member 6-1 of the pointing tool 6 of the present invention as follows. In FIG. 1-2, the relationship between the pointing state of the pointing tool 6 when the lower end of the peripheral frame retroreflective means 3 having the width W2 is mounted at the position d2 from the coordinate input surface 5 is shown. Is. When attention is paid to the tip member 6-1 of the pointing tool 6, when the pointing tool is lowered from the state (a) to (b) in the figure, the light shielding area by the tip member 6-1 increases, so that the shading shadow increases. There is a change that the amount of light decreases. However, when the indicator is lowered from (b) to (c), the tip portion of the tip member 6-1 passes through the non-attached portion d2 of the peripheral frame retroreflecting means 3, and this portion Is outside the range of retroreflected light from the peripheral frame retroreflecting means 3, so that the light shielding area does not change even if the tip member 6-1 is moved, and therefore the light quantity of the light shielding shadow does not change. In view of the above, it is desirable that the non-mounting portion d2 of the peripheral frame retroreflecting means 3 is as small as possible. However, in an apparatus configuration in which the actual display surface of this type of display is the coordinate input surface 5, the coordinate In many cases, it is extremely difficult to make the non-attached portion d2 zero due to a problem such as securing a space for a member portion for supporting the input surface 5. In this case, if an attempt is made to detect pen down or pen up only by the light amount distribution by the light shielding by the tip member 6-1 as it is, only the non-attached portion d2 from the coordinate input surface 5 has no change in the light amount distribution, and is accurate and sensitive. Detection is impossible. Therefore, in the structure of the pointing tool 6 of the present invention, as shown in FIG. 1-2, the mounting position of the pointing tool retroreflecting portion 6-2 from the tip of the tip member 6-1 is the peripheral frame retroreflecting means 3 described above. It is mounted so that it is in a range from a position that is longer (separated) than the shortest distance d2 of the mounting position from the coordinate input area surface to a position d2 + W2 that is longer (separated) than the longest distance. That is, when the mounting distance from the tip of the tip member 6-1 of the pointing tool retroreflective portion 6-2 is d1, and the width of the peripheral frame retroreflective means 3 is W1,
d1> d2
d1 + W1> d2 + W2
The pointing tool retroreflecting unit 6-2 is mounted so that the above relationship is established. With such a configuration of the pointing tool retroreflecting unit 6-2, when the pointing tool 6 is brought into contact with the coordinate input surface 5, the pointing tool retroreflecting unit 6-2 is not attached to the peripheral frame retroreflecting unit 3. It will move in the retroreflective light range other than the part d2, and the light quantity change of the retroreflected light according to the state until the pointing tool 6 contacts the coordinate input surface 5 can be detected by the light receiving detection means. Therefore, pen-down and pen-up can be detected by the light shielding by the tip member 6-1 and the change in the light amount distribution of the retro-reflection by the pointing tool retro-reflecting unit 6-2. Details regarding further specific detection of the light quantity distribution will be described later.

<Detailed explanation of sensor unit>
FIG. 3 is a configuration example of the light projecting means in the sensor unit.

  3-1 is a view of the light projecting unit as viewed from above (perpendicular to the input surface). In the figure, reference numeral 31 denotes an infrared LED that emits infrared light, and the emitted light is projected by a light projection lens 32 in a range of approximately 90 °. On the other hand, 3-2 is a view of the same configuration viewed from the side (in the horizontal direction with respect to the input surface). In this direction, the light from the infrared LED 31 is projected as a light beam restricted in the vertical direction. Light is projected to the retroreflective means 3.

  FIG. 4 is a view of the detection means in the sensor unit as viewed from the direction perpendicular to the input surface.

The detection means includes a one-dimensional line CCD 41, lenses 42 and 43 as a condensing optical system, and a diaphragm 44 that limits the incident direction of incident light. As described above, an infrared filter 45 that prevents the incidence of extraneous light such as visible light may be added.
The light from the light projecting means is reflected by the retroreflective member, passes through the infrared filter 45 and the stop 44, and the light in the approximately 90 ° range of the input surface is incident on the CCD detection surface by the condensing lenses 42 and 43. An image is formed on the pixel depending on the angle, and the light amount distribution for each angle is shown. That is, the pixel number represents angle information.

  FIG. 5 shows a configuration in which the light projecting unit and the detection unit are overlapped to form the sensor unit 1 when viewed from the horizontal direction with the input surface.

  The distance between the optical axes of the light projecting means and the detecting means may be set in a range that can be sufficiently detected from the angular characteristics of the retroreflective member.

<About reflective members>
The peripheral frame retroreflective member 3 in FIG. 1 has a reflection characteristic with respect to an incident angle.

  When the retroreflective tape is configured flat as shown in FIG. 6, the amount of reflected light obtained when the angle from the reflective member exceeds 45 degrees is reduced, and the change occurs when there is a shield. Will not be enough.

  The amount of reflected light is determined by the light amount distribution (illumination intensity and distance), the reflectance of the reflecting member (incident angle, the width of the reflecting member), and the imaging system illuminance (cosine fourth law).

  If the amount of light is insufficient, it is conceivable to increase the illumination intensity. However, if the reflection distribution is not uniform, when a strong portion of light is received, that portion is saturated by the CCD, which is the light receiving means. There is a limit to increasing the illumination intensity.

  In other words, it is possible to increase the amount of light incident on the low light amount portion by making the reflection distribution of the reflecting member as uniform as possible.

  In order to make the angle direction uniform, the member to which the peripheral frame retroreflective member 3 is attached is formed by arranging triangular prisms as shown in FIG. 7, and the peripheral frame retroreflective member 3 is installed thereon. By doing so, the angle characteristics can be improved. The angle of the triangular prism may be determined from the reflection characteristics of the retroreflective member, and the pitch is preferably set to be equal to or less than the detection resolution of the CCD. The structure of the peripheral frame retroreflective member 3 itself is constituted by a bead type, a prism, a corner cube type, or the like, similar to the indicator retroreflecting portion 6-2 of the indicator 6.

<Description of control / arithmetic unit>
Between the control / arithmetic unit of FIG. 1 and the sensor units 1L and 1R, a CCD control signal, a CCD clock signal and a CCD output signal, and an LED drive signal are exchanged.

FIG. 8 is a block diagram of the control / arithmetic unit. The CCD control signal is output from an arithmetic control circuit 83 constituted by a one-chip microcomputer or the like, and performs CCD shutter timing, data output control, and the like. The clock for the CCD is sent from the clock generation circuit 87 to the sensor unit, and is also input to the arithmetic control circuit 83 in order to perform various controls in synchronization with the CCD.
The LED driving signal is supplied from the arithmetic control circuit 83 to the infrared LEDs of the sensor unit through the LED driving circuits 84L and 84R.

  Detection signals from the CCD, which is the detection means of the sensor unit, are input to the AD converters 81L and 81R of the control / arithmetic unit, and are converted into digital values under the control of the arithmetic control circuit.

  The converted digital value is stored in 82 memory and used for angle calculation.

  A coordinate value is obtained from the calculated angle and is output to an external PC or the like via the serial interface 88 or the like.

<Explanation of light intensity distribution detection>
FIG. 9 is a timing chart of control signals.

  Reference numerals 91, 92 and 93 are control signals for CCD control, and the shutter release time of the CCD is determined by the interval of the 91SH signal. 92 and 93 are gate signals to the left and right sensors, respectively, and are signals for transferring the charge of the photoelectric conversion unit in the CCD to the reading unit.

  Reference numerals 94 and 95 denote left and right LED drive signals, and 94 drive signals are supplied to the LEDs via the LED drive circuit in order to light one LED in the first cycle of SH. The other LED is driven in the next cycle. After the driving of both LEDs is completed, the CCD signal is read from the left and right sensors.

  When the signal to be read is not input, a light amount distribution as shown in FIG. 10 is obtained as an output from each sensor. Of course, such a distribution is not necessarily obtained in any system, and the distribution changes depending on the characteristics of the peripheral frame retroreflecting means 3, the characteristics of the LEDs, and changes in time (such as dirt on the reflecting surface).

  In the figure, the A level is the maximum light amount, and the B level is the lowest level.

  That is, in a state where there is no reflected light, the level obtained is near B, and the direction of the A level is increased as the amount of reflected light increases. Thus, the data output from the CCD is sequentially AD converted and taken into the CPU as digital data.

  FIG. 11A is an example of output when input is performed with a conventional pointing tool or finger, that is, when reflected light is blocked.

  Since the reflected light is blocked by the conventional indicator or finger at the portion C, the amount of light is reduced only at that portion.

  Further, in the present invention, as described above, at the tip portion of the pointing tool 6, the pointing tool tip member 6-1 forms a light shielding shadow, and at the same time, the pointing tool recursively disposed on the pointing tool tip member 6-1. The retroreflected light is emitted from the reflecting portion 6-2. Therefore, as shown in FIG. 11B, the light quantity increasing portion D of the light quantity increasing peak due to the retroreflected light exists in the light quantity reducing part C of the light-shielding shadow. Distribution. Accordingly, it is possible to obtain a characteristic light amount distribution instead of a simple light amount decrease distribution due to the conventional light-shielding shadow, and thereby distinguishing from a simple light amount decrease distribution in the case of input by a finger, for example, Can be discriminated from the shading shadow by a part of the hand holding the pointing tool, and the influence of the hand can be removed. Alternatively, by using this characteristic light intensity decrease portion and increase portion, disturbance light can be detected by detecting retroreflected light in combination with a conventional light intensity decrease portion that is easily affected by disturbance light. Therefore, the coordinate detection can be performed with higher accuracy.

  The following relates to an embodiment in which coordinate detection is performed based on a distribution of a reduced portion due to light amount shading, and pen-up and pen-down are determined based on a distribution of a characteristic light-decreasing portion and an increasing portion due to the indicator. explain.

  Specifically, an initial state with no input as shown in FIG. 10 is stored in advance, and whether there is a change as shown in FIG. 11-1 (or FIG. 11-2) in each sample period. If there is a change, an operation is performed to determine an input angle using that portion as an input point.

<Explanation of angle calculation>
In calculating the angle, it is first necessary to detect the light shielding range. For simplicity of explanation, the light amount distribution related to retroreflected light from the pointing tool retroreflecting unit 6-1 is not considered.

  As described above, since the light quantity distribution is not constant due to changes in timekeeping, it is desirable to store it when the system is started. By doing so, for example, even if the retroreflective surface is dirty with dust or the like, it can be used unless it is not completely reflected.

  Hereinafter, data of one sensor will be described, but the same processing is performed on the other.

  When the power is turned on, the CCD output is first AD-converted without illumination from the light projecting means without any input, and this is stored in the memory as Bas_data [N]. This is data including variations in the bias of the CCD and the like, and is data near the level B in FIG. Here, N is a 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 is stored. This data is represented by the solid line in FIG. 10 and is Ref_data [N].

  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, presence / absence 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 following calculation is performed for each pixel for the absolute amount of change, and compared with a predetermined threshold value Vtha.

Norm_data_a [N] = Norm_data [N] − Ref_data [N] (1)
Here, Norm_data_a [N] is an absolute change amount in each pixel.

  Since this process only takes a difference and compares it, it does not use much processing time, and therefore it is possible to determine whether or not there is an input at high speed.

  When the number of pixels exceeding the threshold value 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.

  Here, assuming that the reflectance of the A area has been reduced due to dirt or the like, the distribution of Ref_data [N] at this time has a smaller amount of reflected light in the A area as indicated by 13-1 in FIG. In this state, if an indicator or the like is inserted as shown in FIG. 12 and almost half of the retroreflective member is covered, the amount of reflected light is substantially half. Therefore, the distribution Norm_data [ N] is observed.

  When (1) is applied to this state, the result becomes 14-1 in FIG. Here, the vertical axis represents the differential voltage from the initial state.

  If a threshold is applied to this data, the original input range may be lost. Of course, it can be detected to some extent if the threshold value is lowered, but it may be affected by noise or the like.

  Therefore, if the ratio of change is calculated, the amount of reflected light is the first half in both the A area and the B area, so the ratio is calculated by the following equation.

Norm_data_r [N] = Norm_data_a [N] / (Bas_data [N] − Ref_data [N]) (2)
This calculation result is as shown in FIGS. 14 and 14-2, and is represented by a fluctuation ratio. Therefore, even when the reflectance is different, it can be handled equally and detection with high accuracy is possible.

  The threshold value Vthr is applied to this data, and the angle is determined from the pixel numbers of the rising and falling portions with the center of both as the input pixel.

  FIG. 14-2 is drawn schematically for the sake of explanation, and does not actually rise like this, but shows a different level for each pixel.

FIG. 15 shows an example of detection after the ratio calculation is completed. Assume that when the detection is made with the threshold value Vthr, the rising portion of the light shielding area exceeds the threshold value at the Nrth pixel. Furthermore, it is assumed that Vthr falls below the Nf-th pixel.
Keep the center pixel Np
Np = Nr + (Nf−Nr) / 2 (3)
However, in this case, the pixel interval becomes the minimum resolution.

  In order to detect more finely, a virtual pixel number across the threshold is calculated using the level of each pixel and the level of the previous pixel.

The level of Nr is now Lr Nr−1, and the level of the pixel No. L is Lr−1. Further, if the level of Nf is Lf and the number Nf−1 is Lf−1, the virtual pixel numbers Nrv and Nfv are
Nrv = Nr−1 + (Vthr − Lr−1) / (Lr − Lr−1) (4)
Nfv = Nf−1 + (Vthr − Lf−1) / (Lf − Lf−1) (5)
Virtual center pixel Npv
Npv = Nrv + (Nfv−Nrv) / 2 (6)
Determined by

  Thus, by calculating a virtual pixel number from the pixel number and its level, detection with higher resolution can be performed.

  The method for obtaining the central pixel of the light shielding range from the rise and fall of the light shielding range has been described above for the angle calculation of the present embodiment. However, the object for obtaining the indicated position of the pointing tool 6 is not limited to the light shielding range in the present invention. The light amount distribution detected by the light receiving detection means (sensor) of the present invention is a combination of the light amount distributions of the light shielding portion and the retroreflected light portion shown in FIG. 11-2 as described above. This is a feature of the present invention. However, this light quantity distribution is representative of a specified position on the coordinate input surface of the pointing tool. Actually, the light quantity distribution levels of the light shielding part and the retroreflected light part vary depending on the designated area. The pixel width indicated by C and D in FIG. 11-2 also varies. This is also affected by the positional relationship between the sensor units 1L and 1R and the coordinate input surface 5. As a tendency, the pixel width of the light-shielding range tends to increase when it is close to the sensor units 1L and 1R, and conversely, it becomes narrow when it is far away. At the same time, with respect to the retroreflected light from the pointing tool retroreflecting unit 6-1, the pixel width increases and the light quantity increases when close to the sensor units 1L and 1R. In some cases, saturation occurs when the light is not adjusted. On the other hand, as the distance increases, the pixel width becomes narrower and the peak of the amount of light tends to decrease. Therefore, for example, if the sensor units 1L and 1R are arranged with a sufficient distance from the coordinate input surface 5, the light quantity by the shortest position and the farthest position from the sensor unit 1L or 1R is indicated. The degree of change in the distribution is relatively small. Therefore, it is possible to obtain the central pixel of the light shielding range from the light shielding range in the above embodiment. However, when the sensor units 1L and 1R are arranged at a short distance with respect to the coordinate input surface 5, the shortest position from the sensor unit particularly with respect to the retroreflected light from the pointing tool retroreflecting unit 6-1. In the case of the instruction, the pixel width in the light quantity distribution of the retroreflected light is widened, and as a result, there is a case where the light shielding shadow portion cannot obtain a sufficient range for detecting it. Therefore, in order to prevent this state, depending on the arrangement of the sensor units 1L and 1R, the central pixel of the light shielding range is not obtained from the light shielding range of the above embodiment, but the retroreflection from the pointing tool retroreflecting unit 6-1. A method of obtaining the central pixel of the light quantity peak from the light quantity distribution of light may be used. A specific method for obtaining a pixel is the same as that for obtaining the central pixel from the light shielding range, and only the sign of the light amount distribution is reversed. That is, it is determined whether there is retroreflected light by comparing it with the threshold value. In this case, although detected simultaneously with the light shielding range, the rising and falling states in FIG. 11-2 rise at a, b, c, and d when the retroreflected light is small with respect to a certain threshold. Although two or more downhills are obtained, when the indicated position is close to the sensor and the retroreflected light is large, only the retroreflected light portions b and c are obtained. In each case, the ratio of the change was calculated from the rise and fall of the light amount distribution of the retroreflected light, and calculated in the above-mentioned light shielding range. Similarly to the above, the virtual pixel number is obtained to obtain the center pixel.

  In order to calculate an actual coordinate value from the obtained center pixel number, it is necessary to convert it into angle information.

  In actual coordinate calculation described later, it is more convenient to obtain the value of the tangent at the angle rather than the angle itself.

  A table reference or a conversion formula is used for conversion from the pixel number to tan θ.

  FIG. 16 is a plot of tan θ values against pixel numbers. An approximate expression is obtained for this data, and pixel number and tan θ conversion is performed using the approximate expression.

  For example, when a high-order polynomial is used as the conversion formula, the accuracy can be ensured, but the order and the like may be determined in consideration of the calculation capability and accuracy specifications.

  When a fifth order polynomial is used, six coefficients are required, so this data may be stored in a nonvolatile memory or the like at the time of shipment.

If the coefficients of the fifth-order polynomial are now L5, L4, L3, L2, L1, L0,
tanθ is
tanθ = (L5 * Npr + L4) * Npr + L3) * Npr + L2) * Npr + L1) * Npr + L0 (7)
Can be represented.

  If the same thing is done for each sensor, the respective angle data can be determined.

  Of course, in the above example, tan θ is obtained, but the angle itself may be obtained, and then tan θ may be obtained.

<Description of coordinate calculation method>
Coordinates are calculated from the obtained angle data.

  FIG. 17 is a diagram showing a positional relationship with the screen coordinates.

  Each sensor unit is mounted on the left and right sides of the input range, and the distance between them is expressed as Ds.

  The center of the screen is the origin position of the screen, and P0 is the intersection of the angle 0 of each sensor unit.

  The respective angles are θL and θR, and tanθL and tanθR are calculated using the above polynomials.

At this time, the x and y coordinates of point P are x = Ds * (tanθL + tanθR) / (1 + (tanθL * tanθR)) (8)
y = − Ds * (tanθR − tanθL − (2 * tanθL * tanθR)) / (1+ (tanθL * tanθR)) + P0Y (9)
Calculated by

<Explanation on pen-up and pen-down detection>
As described above, the structure of the pointing tool 6 of the present invention can obtain the light-blocking light amount distribution and the retroreflected light amount distribution at the same time. However, this information is used to explain the detection of pen-up and pen-down. Do. For this explanation, the light quantity distribution in which the light quantity increasing portion of the light quantity increasing peak due to retroreflected light exists in the light quantity decreasing part of the light shielding shadow in FIG. It is easy to understand and shown in FIG. 11-3. The detected light quantity distribution states of FIGS. 11-3 (a), (b), and (c) correspond to the input states (a), (b), and (c) of the pointing tool of FIG. 1-2. . As described above, when attention is paid to the tip member 6-1 of the pointing tool 6, when the pointing tool is lowered (closed to the coordinate input surface 5) from the state (a) to (b) of FIG. Since the light-shielding area due to 6-1 increases, the light-shielding shadow increases, that is, the amount of light decreases, so the light-shielding level h21 in FIG. 11-3 increases from (a) to (b) to h22. At the same time, the retroreflected light level h11 from the pointing tool retroreflecting unit 6-2 increases to h12 from (a) to (b). Further, when the pointing tool is lowered from (b) to (c), the distal end portion of the distal end member 6-1 passes through the non-mounted portion d2 of the peripheral frame retroreflecting means 3, and Is outside the range of retroreflected light from the peripheral frame retroreflecting means 3, so that the light shielding area does not change even if the tip member 6-1 is moved, and therefore the light quantity of the light shielding shadow does not change from h22 to h23. On the other hand, the retroreflected light level h11 from the pointing tool retroreflecting unit 6-2 indicates that the mounting distance of the pointing tool retroreflecting unit 6-2 is d1> d2.
d1 + W1> d2 + W2
Therefore, when the pointing tool is lowered from (b) to (c), the area for retroreflecting from the pointing tool retroreflecting unit 6-2 increases. The retroreflected light level increases from h12 to h13. Therefore, the pen-down is detected by detecting a change in retroreflected light when contacting the coordinate input surface 5. Specifically, for example, if the current light shielding level is h2 and the retroreflected light level is h1, this ratio R = h1 / h2 is always monitored, and when this ratio R exceeds a certain threshold Rs, a pen-down is performed. Also good. This threshold value Hs is, for example, a value close to the state of (c). As described above, according to the method of detecting pen-down and pen-up based on the ratio of the light shielding amount level and the retroreflective light level according to the present invention, the pointing tool 6 has the pointing tool 6 from the coordinate input surface 5 from (a) to (b). The variation in the ratio becomes larger in the state from (b) to (c) until the pointing tool 6 approaches and contacts the coordinate input surface 5 from (b) to (c). As described above, h2 varies less, but h1 continues to vary), so that it can be detected sensitively.

<Flow chart showing the process from data acquisition to coordinate calculation>
FIG. 18 is a flowchart showing steps from data acquisition to coordinate calculation.

  When the power is turned on in S101, various initializations such as port setting of the arithmetic control circuit and timer setting are performed. S103 is a preparation for removing unnecessary charges that is performed only at startup. In a photoelectric conversion element such as a CCD, unnecessary charge may be accumulated when it is not operated. If the data is used as it is as reference data, it becomes impossible to detect or causes false detection. In order to avoid this, data is first read multiple times without illumination. In S103, the number of times of reading is set. In S104, unnecessary data is removed by reading the data a predetermined number of times without illumination.

  S105 is a judgment sentence for repeating a predetermined number of times.

  S106 is fetching of data without illumination as reference data, and corresponds to the above Bas_data.

  The data fetched here is stored in the memory and used for calculation thereafter.

  This and another reference data, data Ref_data corresponding to the initial light amount distribution when illuminated, are taken in S108, and this is also stored in the memory.

  Up to this step is the initial setting operation when the power is turned on, and then the normal capturing operation is performed. In S110, the light amount distribution is taken in as described above, and in S111, the presence / absence of a light-shielding portion is determined based on the difference value from Ref_data. If it is determined that there is no data, the process returns to S110 and capture is performed.

  At this time, if the repetition period is set to about 10 [msec], the sampling rate is 100 times / second.

  If it is determined in S112 that there is a light-shielding area, the ratio is calculated by the processing of Expression (2) in S113. If it is determined in S112 that there is a light-shielding region, it means that it is substantially in proximity (proximity input) as described above (or pen-down state if pen-down is determined in a later step). Accordingly, the coordinate calculation is started after this stage, and it means that the cursor movement based on the calculated coordinate value occurs even when there is no pen down. A rising portion and a falling portion are determined by a threshold with respect to the obtained ratio, and the numbers are stored in a memory S114. Next, the center is calculated by the equations (4), (5) and (6). At this time, as described above, the first rising portion and the last falling portion are used in the calculation in S115. Tan 116 is calculated from the obtained central value by an approximate polynomial, and x and y coordinates are calculated from the Tan θ values of the left and right sensor units using equations (8) and (9) S116. Next, in S117, it is determined whether or not the pointing tool has touched the coordinate input surface, that is, pen-up / down determination. The ratio R = h1 / h2 of the light shielding amount level h2 and the retroreflected light level h1 is compared with a threshold value Rs indicating a pen-down state. If the threshold value is exceeded, it is determined that the pen is up. judge. This is to determine whether the pen (touch) down state corresponding to the left button switch in the so-called mouse mode or the proximity input (proximity) state in which the cursor is moved without pressing the mouse button. Is going. According to this result, down flag setting S118 or reset S119 is performed.

  The above is a case where the coordinates are obtained from the light shielding range, but as described above, the coordinates may be calculated from the light amount distribution of the retroreflected light. A flowchart in this case is shown in FIG. After calculating the ratio with the memory data in s113, the number of rising edges and the number of falling edges are detected by a fixed threshold value in step s114-1, and stored in the memory. Then, in step s114-2, it is determined whether the number of rising edges and the number of falling edges are each greater than 1. If it is determined that the number is too large, it is determined that a sufficient range for detecting the light shielding range is detected, and step s115. -1 except for the first and last rise and fall, that is, pixel detection based on the light quantity distribution of retroreflected light, and when it is determined in step s114-2 that the number of rises and the number of fall are less than 1, respectively. It is determined that only a range of retroreflected light is sufficient for detection, and pixel detection is performed using the first and last rise and fall in step s115-2, that is, the light quantity distribution of the retroreflected light. . The following is the same as the case of obtaining coordinates from the light shielding range.

  Since the coordinate value and the down state are determined, the data is transmitted to the host PC S120. This may be sent by serial communication such as USB, RS232, etc., or by any interface. On the PC side that is sent, the driver interprets the data, and moves the cursor, changes the mouse button state, etc. with reference to the coordinate values, flags, etc., so that the PC screen can be operated.

  When the processing of S120 is completed, the processing returns to S110, and thereafter this processing is repeated until the power is turned off.

  Although not shown in the flowchart of the figure, in the structure of the indicator 6 of the present invention, the light quantity distribution of both the light shielding and the retroreflected light is detected at the same time. It is possible to distinguish between an instruction and an instruction with a finger. The host PC may change the cursor type or line type, or change the application depending on the state, using an instruction state identification flag indicating whether the instruction tool is an instruction or a finger instruction.

  In addition to the above flowchart, if only the light-shielded shadow part and the light-shielded shadow and the light intensity peak peak distribution due to retroreflected light are detected at the same time, it is determined that only the light-shielded shadow part is caused by hand. The coordinates may be calculated excluding that part.

(Second embodiment)
In the embodiment described above, in a part of the tip member 6-1 at the tip portion of the pointing tool 6, the tip member 6-1 is retroreflected at a certain distance from the tip portion contacting the coordinate input surface 5. The configuration is shown in which the pointing tool retroreflecting portion 6-2 is attached to the tip member 6-1. However, as shown in FIG. An indicator retroreflecting portion 6-2 is arranged at the axial center portion of the instrument 6, and a surrounding member 6-3 is provided around the indicator retroreflecting portion 6-1 as shown in the figure. A configuration in which the pointing tool retroreflective portion 6-2 is disposed at a certain distance from the tip portion of the member 6-3 that is in contact with the coordinate input surface 5 may be employed. The upper figure of FIG. 19 is a side view of the distal end portion of the second embodiment of the pointing tool 6, and the lower figure is a sectional view.

  The peripheral member 6-2 is a member made of translucent resin or the like, and the light projected from the light projecting unit and the light reflected by the peripheral frame retroreflecting unit 3 are used as the indicator recursion. When entering the reflection part 6-2, it is arranged so as to pass through the peripheral member 6-3. In the figure, the shape is shown as a side surface of a truncated cone, but a simple conical shape or other shapes may be used as long as the light-shielding portion has a sufficient thickness and shape to be detected as a light amount change.

  Due to the configuration of the indicator 6 in the second embodiment, the light projected from the light projecting means is directly incident on the axial center of the tip of the indicator 6 and, as shown in the figure, The light passes through the member 6-3 and enters the pointing device retroreflecting portion 6-2, where it is retroreflected, and the reflected wave passes through the surrounding member 6-3 and has the above-described 1L and 1R detection means. Reach the sensor unit. On the other hand, the reflected light reflected by the peripheral frame retroreflecting means 3 reaches the peripheral member 6-3 of the pointing tool 6. Here, the light incident on the axial center portion of the peripheral member 6-3 has a high transmittance and a low reflectivity because the incident angle to the peripheral member 6-3 is small as shown in the figure, and the light is transmitted and recurs. The light enters the reflecting portion 6-2, is retroreflected, passes through the surrounding member 6-3 again, and is emitted to the peripheral portion of the coordinate input area. On the other hand, the light incident on the outside shifted from the axial center of the peripheral member 6-3 has a large incident angle, a high reflectance, and a low transmittance, in relation to the angle of the surface of the peripheral member 6-3. Therefore, the amount of transmitted light decreases as indicated by the dotted arrow, and even a small amount of incident light is refracted and attenuated inside the indicating member, and as a result, reaches the sensor unit having the 1L and 1R detection means. The amount of light to be reduced is detected as a shading shadow. Further, although not shown, the light projected from the light projecting means and directly incident on the outer side shifted from the axial center of the tip of the pointing tool 6 is not transmitted and attenuated as in the case of the reflected light. However, this results in attenuation of the amount of light to the peripheral frame retroreflecting means 3, and as a result, it is detected as a light shielding shadow similar to the above by the attenuation of the retroreflected light in the reverse path.

  As described above, due to the structure of the distal end portion of the pointing tool 6 of the present invention, when the coordinate input area is pointed by the pointing tool 6, it is detected by the sensor unit having the 1L and 1R detecting means. The light quantity distribution is a light quantity distribution in which a light quantity increase peak due to retroreflected light exists in the light-shielding shadow.

Furthermore, as shown in FIG. 19, in the positional relationship among the pointing tool retroreflecting unit 6-2, the surrounding member 6-3, and the peripheral frame retroreflecting means 3, the pointing tool retroreflecting unit 6 located at the shaft portion of the pointing tool 6. The mounting position from the axial tip of -2 is longer (separated) from the position that is longer (separated) than the shortest distance d2 of the mounting position from the coordinate input area surface of the peripheral frame retroreflecting means 3. It arrange | positions so that it may be the range covering position d2 + W2. That is, if the mounting distance from the tip of the peripheral member 6-3 of the pointing tool retroreflective portion 6-2 is d1, and the width of the peripheral frame retroreflective means 3 is W1,
d1> d2
d1 + W1> d2 + W2
The pointing tool retroreflecting unit 6-2 is arranged so that the above relationship is established. With such a configuration of the pointing tool retroreflecting unit 6-2, when the pointing tool 6 is brought into contact with the coordinate input surface 5, the pointing tool retroreflecting unit 6-2 is not attached to the peripheral frame retroreflecting unit 3. It will move in the retroreflective light range other than the part d2, and the light quantity change of the retroreflected light according to the state until the pointing tool 6 contacts the coordinate input surface 5 can be detected by the light receiving detection means. Therefore, pen-down and pen-up can be detected by the light shielding by the surrounding member 6-3 and the change in the light quantity distribution of the retro-reflection by the pointing tool retro-reflecting unit 6-2. In particular, in this second embodiment, the amount of light shielded by the surrounding member 6-3 is not only adjusted in the axial length direction of the pointing tool retroreflecting portion 6-2, but also differs in each diameter. By doing so, it is possible to form a light quantity distribution of the light-shielding shadow and the retroreflected light that is easier to detect, and to increase the stability of pen-up and pen-down detection. Of course, the effect of identifying the finger and the pointing tool, correcting the hand movement, and improving the accuracy of the coordinate detection is further promoted. A more specific method for detecting the light quantity distribution is the same as that in the above embodiment.

(Third embodiment)
In the above embodiment, when detecting pen-up and pen-down, if the light shielding amount level is h2, and the retroreflected light level is h1, this ratio R = h1 / h2 is always monitored, and this ratio R is a certain threshold value. A method of pen-down when Rs was exceeded was used. As a third embodiment, the ratio R between the specific light shielding amount level h2 and the retroreflected light level h1 is not simply compared with a threshold value, but the ratio is sampled at a certain time interval. A method of pen-down when the amount of change per unit time becomes a constant value may be used. This is because when the pen is down, the tip of the indicator 6 is in contact with the coordinate input surface 5, so that the light distribution by the indicator and the light quantity distribution of retroreflected light are stable, and therefore the amount of change with time is small and stable. doing. It is monitored whether or not this stable state is reached, and pen-down is determined. This method can perform more stable detection than a case where a fixed threshold value is used as a method for dealing with fluctuations in retroreflected light depending on the distance from the sensor unit. Further, not only the problem of distance, but also the variation of the ratio R due to the difference in reflected light from the peripheral frame retroreflecting material depending on the location can be dealt with. Compared to the case of detecting this time change based only on the conventional shading shadow, the state of the vicinity of the coordinate input surface can be reflected more by detecting the shading and retroreflected light with the pointing tool of the present invention.

The schematic structure of the coordinate input device which concerns on this invention, and the front-end | tip part of an indicator, and a periphery retroreflection part structure. The block diagram of the reflection means which has a retroreflection surface. The structural example of the light projection means in a sensor unit. The figure which looked at the detection means in a sensor unit from the perpendicular direction with respect to the input surface. A configuration in which the light projecting unit and the detection unit are overlapped to form the sensor unit 1 when viewed from the input surface and the horizontal direction. The relationship between the amount of reflected light and the reflection angle when the retroreflective tape is flat. Retroreflective member with triangular prisms arranged side by side. Block diagram of the control / arithmetic unit. The timing chart of a control signal. The figure which shows light quantity distribution. Light intensity distribution when input is made with an indicator. The figure which shows a light-shielding state. Reflected light quantity distribution diagram. Reflected light quantity distribution diagram. An example of detection after the ratio calculation is finished. The figure which plotted the tan (theta) value with respect to a pixel number. The figure which shows the positional relationship with a screen coordinate. The flowchart which showed the process from data acquisition to coordinate calculation. The figure which shows the indicator structure in a 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor unit 2 Control / arithmetic unit 3 Peripheral frame retroreflective means 5 Coordinate input surface 6 Pointer 6-1 Pointer tip member 6-2 Pointer retroreflective part 6-3 Surrounding member

Claims (4)

A plurality of light receiving detection means are provided at the corners of the coordinate input area surface,
A peripheral frame retroreflecting means that recursively reflects incident light provided around the coordinate input area surface, and a light projecting means that projects light onto the peripheral frame retroreflecting means;
An angle detection unit for detecting a direction instructed by an indicator or the like from a change in the amount of light from the light projecting unit reflected by the peripheral frame retroreflecting unit detected by the light receiving detection unit; An optical coordinate input device that calculates position coordinates on a coordinate input area surface designated by the pointing device based on angle information,
A light shielding part that shields reflected light from the peripheral frame retroreflecting means and a projection of the pointing tool in contact with the coordinate input area surface within the detection range of the light receiving detection means. A coordinate input device comprising an indicator retroreflecting portion provided at a position where the light from the light means is retroreflected.   In Claim 1, the mounting position of the pointing tool retroreflecting portion from the tip of the pointing tool is longer (separated) than the shortest distance of the mounting position from the coordinate input area surface of the peripheral frame retroreflecting means. A coordinate input device characterized by a range extending over a position longer (away from) the longest distance.   In claim 1, from the light quantity change information detected by the light receiving detection means, the light shielding shadow by the light shielding portion of the indicator and the retroreflected light by the indicator retroreflecting portion of the indicator, the indication A coordinate input device comprising means for detecting a position coordinate on a coordinate input area surface designated by a tool or the like, and a contact state with the coordinate input area surface.   In claim 1, the ratio of the amount of light shaded by the light shielding portion of the indicator and the amount of retroreflected light by the indicator retroreflecting portion of the indicator, which is detected by the light receiving detector, is calculated. A coordinate input apparatus comprising means for detecting a contact state with respect to a coordinate input area surface by a change in the ratio.

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