JPH0816306A - Optical position detector - Google Patents

Abstract

PURPOSE:To provide the optical position detector with which information expressing characters or graphics written on a tablet can be immediately obtained. CONSTITUTION:This device is composed of a tablet 1, writing object 3 equipped with a light reflection plane 3 and position detector 2 fitted onto the tablet 1 so as to detect the position of the writing object 3 on the tablet 1 with light, and the position detector 2 is provided with a polygon mirror 7 to be rotated, a pair of light sources 9 and 10 for projecting light onto the polygon mirror 7, a pair of light receiving elements 11 and 12 for receiving the reflected light of the polygon mirror 7 or the writing object 3 and outputting detecting signals, reference light receiving element 13 for receiving the reflected light of the polygon mirror 7 and outputting a synchronizing signal, arithmetic part for performing various kinds of arithmetic, and control part for controlling respective parts. Based on the output time difference of respective detecting signals from the synchronizing signal, the incident/exit angle of light made incident on the writing object 3 on the reflection plane of the polygon mirror 7 is calculated, and the rectangular coordinate position of the writing object 3 on the tablet 1 is detected by prescribed arithmetic using the incident/exit angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical position detecting device, and more particularly to a large writing board such as a whiteboard for writing characters and figures with a writing body such as a marker pen. Of the optical position detecting device, which sequentially obtains the information representing the characters and figures by sequentially detecting the position on the writing plate.

[0002]

2. Description of the Related Art Generally, a blackboard has a chalk on which characters and figures can be written, and written characters and figures can be erased with a blackboard eraser. The writing board can also be used to write characters and figures with a marker pen, and erase written characters and figures.As a writing board that can be used repeatedly, classrooms have been used instead of the previously used blackboard. It has come to be widely used in conference rooms and the like. In particular, recently, a technical means has been developed to print out the characters and figures written on the whiteboard on the spot, and the characters and figures written on the whiteboard can be printed without the need to copy them. A copy can be easily obtained.

[0003]

By the way, in such a known whiteboard, even if a copy of written characters or figures can be easily obtained, in order to edit the obtained copy, After copying the contents of the copy on the whiteboard again, you have to make the necessary edits on the whiteboard and obtain it again by printing out, and also transfer the obtained copy to other departments. In order to do so, the copy must be transmitted to the other party through a communication line using a transmission device such as a facsimile machine. Furthermore, in order to record and store the obtained copy in the form of information, the copy must be transmitted. It is necessary to read the contents of the above into an information device such as a personal computer through some input device and record and store the read information in the device information.

As described above, in the known whiteboard, since the copy of the character or figure written in the whiteboard is simply obtained, some processing is performed on the copy of the obtained character or figure. When you want to do, for example,
When it is desired to perform the above-mentioned editing, transmission to other departments, or recording and storage in the form of information, there is a problem that a desired one cannot be obtained unless a complicated procedure is performed.

The present invention is intended to eliminate the above-mentioned problems, and an object thereof is to provide an optical position detecting device capable of immediately obtaining information representing characters, figures, etc. written on a writing board. To do.

[0006]

In order to achieve the above object, the present invention provides a writing and erasable writing plate, a writing body having a light-reflecting surface at its tip, and a writing plate attached to the peripheral portion of the writing plate. A position detector for detecting the position of the writing body on the writing plate by light, wherein the position detector is
A polygon mirror that rotates about a central axis, a pair of light sources that are symmetrically arranged with respect to the central axis and that are arranged to project light onto the polygon mirror, and a symmetrical arrangement with respect to the central axis. A pair of light-receiving elements arranged to receive the light sequentially reflected by the polygon mirror and the reflecting surface of the writing body, and output detection signals representing the position of the writing body; and the polygon. One reference light receiving element arranged so as to directly receive the reflected light from the mirror and output a synchronization signal having a constant period,
An operation unit that performs various operations and a control unit that controls each unit are provided, and the light is incident on the reflection unit of the cursive body based on the output time difference between the two detection signals with respect to the synchronization signal.
Means is provided for obtaining an incident / emission angle on the reflection surface of the polygon mirror with respect to one light and detecting a rectangular coordinate position of the writing body on the writing plate by a predetermined calculation using the two incident / emission angles.

[0007]

According to the above means, the peripheral edge of the writing plate receives a polygon mirror, a pair of light sources for projecting light on the polygon mirror, and light sequentially reflected by the reflecting section of the polygon mirror and the writing body. A pair of light receiving elements that respectively output detection signals representing the position of the cursive body, one reference light receiving element that directly receives the reflected light from the polygon mirror, and outputs a synchronization signal of a constant cycle, a computing unit, and a control unit. A position detector with and is attached. In this case, the position detector uses the difference in the output times of the one reference light receiving element and the pair of light receiving elements within each minute time, and the two lights incident on the reflecting portion of the writing body enter the anti-slope surface of the polygon mirror. The exit angles θ ₁ and θ ₂ are measured, and the two measured entrance and exit angles θ
_A predetermined calculation is performed by the calculation unit using ₁ and θ _2, and the rectangular coordinate position of the writing body on the writing plate, that is, the position on the x coordinate and the position on the y coordinate is obtained by the calculation.
If the position on the x-coordinate and the position on the y-coordinate of the cursive body is continuously obtained, it is possible to determine the route that the cursive body has followed on the writing board, and thereby write on the writing board. It becomes possible to read the letters and figures in the form of information (data).

As described above, according to the above-mentioned means, by transmitting the read information (data) to the information equipment such as the personal computer, a large amount of the read information (data) can be stored and stored in the information equipment. Moreover, if the information (data) stored and stored in this information device is used, the information (data) read on the information device, that is, the characters and figures written on the writing board can be easily reproduced. It becomes possible to edit, and it becomes possible to easily transmit the information (data) that is also read by using the information device, that is, the characters and figures written on the writing board to other departments. .

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of an optical position detecting device according to the present invention, in which a white board is used as a writing board and a marker pen is used as a writing body.

As shown in FIG. 1, a whiteboard (writing board) 1 has a position detector 2 attached to a substantially central portion of an upper edge thereof, and a marker pen (writing body) 3 for writing on the whiteboard 1 has a tip. A light reflection ring (light reflection surface) 4 is attached to the portion. The position detector 2 is a device driver 5
Is connected to a personal computer (information device) 6 via. In this case, the position detector 2 includes a polygon mirror 7 that rotates about the central axis 7a, a motor 8 that rotates the polygon mirror 7, a polygon mirror 7 that is relatively close to the polygon mirror 7, and
A pair of laser light sources 9 and 10 that are arranged symmetrically with respect to the axis 7a and project laser light onto the polygon mirror 7, and are separated from the polygon mirror 7, and with respect to the axis 7a. A pair of laser light receiving portions 11 and 12 which are arranged at symmetrical positions and receive the laser light reflected by the polygon mirror 7 and the light reflection ring 4 of the marker pen 3, and are arranged relatively close to the polygon mirror 7. And one reference laser light receiving portion 13 for receiving the laser light reflected by the polygon mirror 7.

FIG. 2 is a block diagram showing the outline of the internal structure of the position detector 2 in the embodiment shown in FIG. 2, the same components as those shown in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 2, the position detector 2 is
A motor driving unit 14 including a motor 8 for rotating the polygon mirror 7, a laser light source unit 15 including a pair of laser light sources 9, 10 and a pair of laser light receiving units 11,
12 and one reference laser light receiving unit 13, a laser light receiving unit 16, a laser light source driving unit 17 that drives the laser light source unit 15 under the control of the control unit 20, and a light receiving output signal obtained by the laser light receiving unit 16. The detection amplification unit 18 that detects and supplies the detection output to the subsequent calculation unit 19, the calculation unit 19 that calculates the detection output of the detection amplification unit 18, and each unit are controlled, and necessary information is created and stored. It is composed of a control unit 20 for storing and a power supply unit 21 for supplying operating power to the motor drive unit 14, the control unit 20, and the like.

Further, FIG. 3 is an explanatory view showing an example of each of a laser light transmission path in the position detector 2 in the embodiment shown in FIG. 1 and a light reception output signal obtained at a laser light receiving portion, (a) is an explanatory view showing an example of a path until the laser light projected from one laser light source 9 is incident on the one laser light receiving portion 11 and the reference laser light receiving portion 13, and (b) is a reference laser light receiving portion. It is explanatory drawing which shows an example of the light reception output signal obtained in 13 and one laser light receiving part 11. Also in FIG. 3A, the same components as those shown in FIG. 1 are designated by the same reference numerals.

As shown by the solid line in FIG. 3A, when the polygon mirror 7 is at the rotation angle shown by the solid line at a certain time, the laser light projected from one of the laser light sources 9 onto the polygon mirror 7 is a polygon. The reflected laser light reflected by one of the reflecting surfaces of the mirror 7 is dissipated without being incident on the reference laser light receiving portion 13, and the other reflected laser light E is re-reflected by the light reflecting ring 4 of the marker pen 3. Then, the light is incident on one of the laser light receiving units 11. At this time, as shown in FIG. 3B, the light receiving output signal A is output from one of the laser light receiving units 11.

Further, as shown by the dotted line in FIG. 3A, when the polygon mirror 7 rotates by a predetermined angle and is at the rotation angle shown by the dotted line, one of the laser light sources 9 projects it onto the polygon mirror 7. The laser light is reflected by one reflecting surface of the polygon mirror 7, and the reflected laser light is incident on the reference laser light receiving unit 13. At this time,
As shown in (b), the reference laser light receiving unit 13 outputs the synchronizing signal B after the light receiving output signal A by a time Δt. Then, the rotation angle θ of the polygon mirror 7 is detected from the difference Δt between the output timing of the synchronization signal and the output timing of the received light output signal.

Here, by fixing the reference laser light receiving portion B at a predetermined position, an angle θs formed by the incident light C from the laser light source 9 to the reflecting surface of the polygon mirror and the reflected light D to the light receiving portion B is set. , A predetermined angle. In addition, the rotation angle θ of the polygon mirror 7 is determined by the reflected light D
And the reflected laser light E to the light reflection ring 4 makes an angle.

Therefore, the angle θ ₁ formed by the incident light C from the light source 9 to the polygon mirror reflecting surface and the reflected laser light E is the difference between the rotation angle θ and the angle θs, and the angle θ ₁ can be calculated. Similarly, the angle θ ₂ between the incident light from the light source 10 on the reflecting surface of the polygon mirror and the reflected light on the light reflecting ring 4 is θ _2.
Is calculated from the difference between the rotation angle θ ′ of the polygon mirror and the angle θs.

FIG. 4 is an explanatory diagram showing an example of obtaining the x, y coordinate position of the marker pen 3 on the whiteboard 1 in the embodiment shown in FIG. The same components as those shown are designated by the same reference numerals.

In FIG. 4, the whiteboard 1 is in the horizontal direction.
The upper x-axis direction and the vertical direction are the y-axis directions on the whiteboard 1, and the origin 0 of the x and y coordinate axes is the arrangement position of the central axis 7a of the polygon mirror 7. In this case, the x-axis becomes the axis that coincides with the optical axis of the laser light, and the y-axis becomes the axis that coincides with the central axis 7a. Further, points -a and a on the x-coordinate axis represent reflection point positions when the laser beams projected from the one and the other laser light sources 9 and 10 are reflected by the reflection surface of the polygon mirror 7, respectively. The upper points -b and b are
The positions of the emission points of the laser light projected from the one and the other laser light sources 9 and 10 are shown, and the points −c and c on the x-coordinate axis are the laser light reflected from the light reflection ring 4 of the marker pen 3, respectively. It shows the position of the light receiving point of the one and the other laser light receiving portions 11 and 12 which are incident,
Each point -a, a, -b, b, -c, c is the central axis 7
The positions are symmetrical with respect to a, and each point −a, a, −
The coordinate positions of b, b, -c, and c on the x-axis, that is, the distances from the origin 0 to these points -a, a, -b, b, -c, and c are as the configuration of the position detector 2. Since the physical length is set, both are known.

The operation of this embodiment will be described with reference to FIGS. 1 to 4. However, in this description, it is assumed that the marker pen 3 is at the pen position P1 (x coordinate position xp and y coordinate position yp) shown in FIG.

First, the polygon mirror 7 has a motor 8
By the urging of the center axis 7a, the center axis 7a is rotated in a constant direction at a constant rotation speed. A pair of laser light sources 9, 10
Is energized by a drive current applied from the laser light source drive unit 17 at regular intervals, and the laser light is projected toward the reflecting surface of the polygon mirror 7 at the same regular cycles. At this time, the laser light projected from one laser light source 9 is reflected by one reflecting surface of the polygon mirror 7, and one reflected laser light travels toward the reference laser light receiving portion 13 and the other reflected laser light. Moves in the direction of the marker pen 3 at the pen position P1. Then, each time each reflecting surface of the polygon mirror 7 makes a first angle with respect to the laser light source 9, the reflected laser light traveling in the direction of the reference laser light receiving portion 13 is incident on the reference laser light receiving portion 13.
At this time, the reference laser light receiving unit 13 responds to the incidence of the reflected laser light and generates a synchronization signal with a constant period.

When the reflection surface of the polygon mirror 7 becomes the second angle with respect to the laser light source 9, the reflected laser light reflected by the reflection point -a of the polygon mirror 7 and traveling in the direction of the marker pen 3 is changed to the marker. It is incident on the light reflection ring 4 of the pen 3. The light reflecting ring 4 re-reflects the incident reflected laser light and makes it enter one of the laser light receiving portions 11 at the light receiving point -c. At this time, the laser light receiving unit 11 generates a first light reception output signal in response to the incident reflected laser light.

On the other hand, the laser light projected from the other laser light source 10 is also reflected at the reflection point a of the polygon mirror 7.
The reflected laser light is reflected by and travels in the direction of the marker pen 3 at the pen position P1. And the polygon mirror 7
When one of the reflection surfaces becomes a third angle with respect to the laser light source 9, the reflected laser light reflected by the reflection point a of the polygon mirror 7 and traveling in the direction of the marker pen 3 is reflected by the light reflection ring 4 of the marker pen 3. Is incident on. Light reflection ring 4
Re-reflects the incident reflected laser light and makes it incident on the other laser light receiving portion 12. At this time, the other laser light receiving section 12 generates a second light receiving output signal in response to the incident reflected laser light.

Next, the synchronization signal output from the reference laser light receiving unit 13 and one and the other laser light receiving units 11,
The first and second received light output signals output from 12 are supplied to the detection amplification section 18, and after these signals are amplified and shaped, they are supplied to the calculation section 19. At this time, the calculation unit 19 determines the output timing of the synchronization signal and the first light reception output signal or the output timing of the synchronization signal and the second light reception output signal. When it is determined that the output timings match, as described above, based on the angle data of the reflecting surface of the polygon mirror 7, the laser light (laser light Axis) and reflected laser light
₁ or θ ₂ is detected, that is, the incident / exit angle θ ₁ or θ formed by the reflected laser light and the laser light (laser light optical axis) incident at the reflection points −a, a of the polygon mirror 7
₂ detection is performed. On the other hand, when it is determined that the output timings do not match, as described above, the difference between the output timing of the synchronization signal and the output timing of the first or second light receiving output signal causes the same. On the basis of the angle data of the reflecting surface of the polygon mirror 7, the incident / exiting angle θ ₁ ′ formed by the reflected laser light and the laser light (laser light optical axis) incident on the reflecting surface. Or θ ₂ '
Detection, that is, the incident / exit angle θ ₁ ′ formed by the reflected laser light and the laser light (laser light optical axis) incident at the reflection points −a and a of the polygon mirror 7. , Θ ₂ ' Is detected.

In this way, the incident / exit angles θ ₁ , θ ₂ (or the incident / exit angle θ ₁ ′ formed by the incident laser light and the reflected laser light at the reflection points -a, a) , Θ ₂ ' ) Is detected, the calculation unit 19 subsequently performs the following calculation from the position and angular relationship of each unit illustrated in FIG. 4 to perform the following calculation, and the existing pen on the white boat 1 of the marker pen 3 is detected. A rectangular coordinate position of the position P1, that is, an x coordinate position xp ₁ and ay coordinate position yp ₁ are obtained.

Tan θ ₁ = yp ₁ / (− xp ₁ + a) ... (1) tan θ ₂ = yp ₁ / (− xp ₁ −a) ... (2) where (tan θ ₂ / tan θ ₁ ) = U, xp ₁ =-[a (U + 1)] / (U-1) ... (3) yp ₁ = [{-a (U + 1) / (1-U)} + a] (tan θ ₁ ) (4) By performing such a calculation, the existing position of the marker pen 3 on the whiteboard 1, that is, the pen position P1,
The point P1 can be represented by the x-coordinate position xp ₁ and the y-coordinate position yp ₁ .

In the above example, the marker pen 3 has the pen position P.
Although the case where the marker pen 3 currently exists at 1 (x coordinate position xp ₁ and y coordinate position yp ₁ ) has been described, the marker pen 3 is constantly moving on the whiteboard 1 and its position is constantly changing. Accordingly, the x-coordinate position xp _i and the y-coordinate position yp _i obtained at the existing pen position PI constantly change. Then, for example, even if the marker pen 3 is present at the pen position P2 (x coordinate position xp ₂ and y coordinate position yp ₂ ) at a certain time point, the pen position P1 (x coordinate position xp ₁ and y coordinate position y) is present.
The coordinate position xp ₂ and the y coordinate position yp ₂ of the point P2 can be obtained in exactly the same manner as the case of obtaining p ₁ ).

However, when the pen position P2 is to be obtained, other entrance / exit angles θ ₁ ′ are used instead of the entrance / exit angles θ ₁ and θ _2. , Θ
₂ ' Is used and the x-coordinate position xp ₂ becomes positive, so that xp ₂ = [a (U + 1)] / (U−1) ... (3 ′).

The detection of the x-coordinate position and the y-coordinate position of the marker pen 3 on the whiteboard 1 is repeated continuously while the characters and figures are being written on the whiteboard 1 by the marker pen 3. The x-coordinate position and the y-coordinate position detected at each time point are supplied from the calculation unit 19 to the control unit 20.

At this time, the control unit 20 determines what the characters and figures written on the whiteboard 1 are based on the locus drawn by tracing the x-coordinate position and the y-coordinate position at each time point. Determine if there is. The determination of the character or figure may be performed by using a determination unit that compares the locus drawn by the x-coordinate position and the y-coordinate position with the character or figure stored and stored in the storage unit (not shown). Other determination means may be used. Control unit 20
Confirms that the locus drawn by the x-coordinate position and the y-coordinate position is a specific character or figure, and represents the confirmed character, figure, or the like by the locus drawn by this x-coordinate position and y-coordinate position. It is converted into unique information (data), and the converted unique information (data) is temporarily stored in a storage unit (not shown). Then, the unique information (data) temporarily stored and stored is appropriately read from the position detector 2, and the device driver 5
Is transmitted to the information device 6 such as a personal computer via the.

In this case, between the unique information (data) temporarily stored and stored in the storage unit of the position detector 2, the unique information temporarily stored and stored in the storage unit of the position detector 2. Between the (data) and the unique information (data) transmitted to the information device 6 such as a personal computer, or the position detector 2
When it is desired to edit the information (data) between the unique information (data) temporarily stored and stored in the storage unit of the and the character, figure, etc. to be written on the whiteboard 1, for example, the position All the unique information (data) stored in the detector 2 and the unique information (data) obtained by the position detector 2 are transmitted to the information device 6 such as a personal computer, and the information device 6 such as the personal computer is transmitted. It may be performed according to a normal information editing means using.

Further, when it is desired to transmit the unique information (data) stored and stored in the position detector 2 or the unique information (data) obtained by the position detector 2 to another department, similarly. These unique information (data) may be transmitted to the information equipment 6 such as a personal computer, and the information equipment 6 such as the personal computer may be used in accordance with a normal information transmission means.

Further, when it is desired to store and accumulate a large amount of unique information (data) obtained by the position detector 2, similarly, such a large amount of unique information (data) is transmitted to the information device 6 such as a personal computer. Then, this information device 6 such as a personal computer
May be performed in accordance with the normal information storage and storage means.

In the above-mentioned embodiment, the writing board is the whiteboard 1 and the writing body is the marker pen 3. However, the writing board and the writing body according to the present invention are the whiteboard. It is needless to say that the writing board similar to the whiteboard 1 and the writing body similar to the marker pen 3 are not limited to the 1 and the marker pen 3.

Further, in the above-mentioned embodiment, the case where the laser light sources 9, 10 are used as the light sources and the laser light receiving portions 11, 12, 13 are used as the light receiving portions has been described as an example, but according to the present invention. The light source and the light receiving unit are laser light sources 9, 1
It is not limited to 0 or the laser light receiving units 11, 12, and 13, and a light source that generates ultraviolet light, infrared light, or the like and a light receiving unit that receives ultraviolet light, infrared light, or the like may be used. .

[0037]

As described above, in the present invention, the polygon mirror 7, the pair of light sources 9 and 10 for projecting light to the polygon mirror 7, the polygon mirror 7 and The reflected light from the polygon mirror 7 is directly received by the pair of light receiving elements 11 and 12 which receive the light sequentially reflected by the reflecting portion 4 of the writing body 3 and output the detection signals representing the position of the writing body 3. , One reference light-receiving element 13 that outputs a synchronization signal of a fixed cycle, and an arithmetic unit 1
The position detector 2 including 9 and the control unit 20 is attached. Here, the position detector 2 has one reference light receiving element 13 and a pair of light receiving elements 11 within each minute time.
From the output time difference of 12, the incident and outgoing angles θ ₁ and θ ₂ of the two lights entering the reflecting portion 4 of the writing body 3 at the reflecting surface of the polygon mirror 7 are measured, and the measured two incoming and outgoing angles θ ₁
A predetermined calculation is performed by the calculation unit 19 using θ _2, and the rectangular coordinate position of the writing body 3 on the writing plate 1 is calculated by the calculation.
That is, the position on the x coordinate and the position on the y coordinate are obtained.

As described above, according to the present invention, the route of the writing body 3 on the writing board 1 is determined by continuously obtaining the position of the writing body 3 on the x coordinate and the position of the y coordinate. As a result, it is possible to directly read the characters and figures written on the writing board 1 in the form of information (data).

Further, according to the present invention, if the read information (data) is transmitted to the information device 6 such as a personal computer and stored in the information device 6 or the like, a large amount of read information (data) is obtained. In addition to storing and accumulating information, if the read information (data) is transmitted to the information device 6 and the information (data) is edited on the information device 6, the read information can be easily read. (data)
It becomes possible to perform re-editing between them, and if the read information (data) is transmitted to the information device 6 and information is transmitted using the information device 6, the read information can be easily read. (Data) can be transmitted to other departments.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an optical position detecting device according to the present invention.

FIG. 2 is a block configuration diagram showing an outline of an internal configuration of a position detector 2 in the embodiment shown in FIG.

FIG. 3 is an explanatory view showing an example of a light receiving output signal obtained in a laser light transmission path and a laser light receiving section in the position detector in the embodiment shown in FIG.

FIG. 4 is an explanatory diagram showing an example of a case in which x, y coordinate positions of a marker pen on a whiteboard in the embodiment shown in FIG. 1 are obtained.

[Explanation of symbols]

 1 Whiteboard (writing board) 2 Position detector 3 Marker pen (writing body) 4 Light reflection ring (light reflection surface) 5 Device driver 6 Personal computer (information equipment) 7 Polygon mirror 7a Center axis 8 Motor 9 One laser light source 10 Other laser light source 11 One laser light receiving unit 12 Other laser light receiving unit 13 Reference laser light receiving unit 14 Motor driving unit 15 Laser light source unit 16 Laser light receiving unit 17 Laser light source driving unit 18 Detection amplification unit 19 Computing unit 20 Control unit 21 Power supply Department

Claims (3)

[Claims] 1. A writing and erasable writing plate, a writing body having a light-reflecting surface at its tip, and a writing member attached to the peripheral portion of the writing plate to detect the position of the writing body on the writing plate by light. And a position detector, wherein the position detector is
A polygon mirror that rotates about a central axis, a pair of light sources that are symmetrically arranged with respect to the central axis and that are arranged to project light onto the polygon mirror, and a symmetrical arrangement with respect to the central axis. A pair of light-receiving elements arranged to receive the light sequentially reflected by the polygon mirror and the reflecting surface of the writing body, and output detection signals representing the position of the writing body; and the polygon. One reference light receiving element arranged so as to directly receive the reflected light from the mirror and output a synchronization signal having a constant period,
An operation unit that performs various operations and a control unit that controls each unit are provided, and the light is incident on the reflection unit of the cursive body based on the output time difference between the two detection signals with respect to the synchronization signal.
An optical system characterized in that an entrance / exit angle of the reflecting surface of the polygon mirror with respect to one light is obtained, and a rectangular coordinate position of the writing body on the writing plate is detected by a predetermined calculation using the two entrance / exit angles. Position detection device. 2. The pair of light sources are laser light sources, and the pair of light receiving elements and the one reference light receiving element are laser light receiving elements, according to claim 1. Optical position detector. 3. The optical position detecting device according to claim 1, wherein the writing plate is a white board, and the writing body is a marker pen.