JPS6334962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an obstacle position detection method that detects the coordinates of an obstacle on a plane by scanning light.

[Conventional technology]

Conventionally, as a device for detecting the coordinates of an arbitrary point on a scanning line, when an electron beam scans the entire display screen at a constant period, a light-receiving element such as a phototransistor at the tip of the light pen is From the timing of detecting this electron beam,
A light pen method that detects the coordinates of a point pointed on a screen is widely known.

〔assignment〕

However, since this conventional device requires a code that connects to the light pen and provides instruction information, it lacks maneuverability when the range of point coordinates to be detected is expanded, and moreover, raster scanning cannot be performed on the display screen. There was a drawback that point coordinates could not be detected unless the

The present invention improves this and aims to provide a simple obstacle position detection method capable of detecting point coordinates on a plane.

[Configuration of the present invention]

The present invention provides a method for bending light of different optical paths emitted from the same position on one side of two opposing sides out of four sides surrounding a coordinate plane for detecting the position of an obstacle. A first optical path bending means that makes parallel optical paths that the bent light can take correspond to the coordinate plane, such as a Fresnel mirror or Fresnel mirror that has a large number of parabolic mirrors or plane mirror pieces arranged in a straight line. a lens, and a second optical path bending means placed on the other of the two opposing sides of the coordinate plane to converge the parallel incident light to the same point, such as a parabolic mirror or a Fresnel mirror, or a Fresnel lens or a glass fiber bundle; a rotary bending means, such as a rotary polygon mirror or a rotary prism, which serves as a light emitting point and is placed at the position for scanning the light beam with respect to the first optical path bending means; A light source, such as a laser light source, that irradiates the rotational bending means with parallel light beams having a cross-sectional area that is not larger than the area of the area where the parallel light beams are blocked by the target obstacle, and the second optical path bending means. Therefore, a photodetector, such as a photoelectric conversion device, is provided at a point where the incident parallel rays are concentrated at one point, and an obstacle to be detected is placed within the coordinate plane, and the object is bent and scanned parallel to each other. The present invention is characterized in that the position of the obstacle in the coordinate plane is calculated from an intermittent signal that can determine the presence or absence of light reaching the photodetector based on the output of the photodetector.

As an example, the present invention includes mirrors arranged in large numbers on each of the four sides to surround a coordinate plane for detecting the position of an obstacle, and mirrors arranged on the diagonals of the four sides near the intersection of the four sides. A rotating polygon mirror that scans the light beam toward the mirror, which is placed on two sides of the four sides opposite to the intersection, and a rotating polygon mirror that is placed on the diagonal of the four sides and near the intersection opposite to the intersection. and a laser light source that irradiates the light beam bending means, and when the output light of the laser light source is scanned by the light beam bending means, it is reflected by mirrors on two opposite sides of the four sides. The orientation of the mirror is set to reach the photodetector,
The present invention is characterized in that the position of the obstacle on the coordinate plane is calculated from the intermittent signal appearing in the output of the photodetector.

〔Example〕

Next, the present invention will be explained in detail by way of examples based on the drawings.

FIG. 1 is a basic configuration diagram of an apparatus according to a first embodiment of the present invention.

In the figure, a laser light source 1 is fixedly provided and continuously sends laser light to a rotating polygon mirror 2, which is a rotating bending means. The rotating polygon mirror 2 is provided near one corner of a rectangular tablet frame 3, which serves as a coordinate plane for detecting the position of an obstacle, and on a diagonal line of the tablet frame 3. This rotating polygon mirror 2 rotates counterclockwise at a constant angular velocity. Also, on the diagonal line above, tablet frame 3
A photodetector 4 equipped with a photoelectric conversion element is provided near a corner opposite to the above-mentioned corner.

Furthermore, there are mirrors 5 on the outside of the four sides of the tablet frame 3.
are placed in large numbers. In other words, tablet frame 3
32 mirrors 5x ₁ along one side 3X in the horizontal direction,
5x ₂ ,..., 5x ₃₂ are provided as first optical path bending means, along the other horizontal side 3x of the tablet frame 3, and facing 5x ₁ , 5x ₂ ,..., 5x ₃₂ .
Mirrors 5x' ₁ , 5x' ₂ , . . . , 5x' ₃₂ are provided as second optical path bending means. Furthermore, tablet frame 3
32 mirrors 5y ₁ along one side 3Y in the vertical direction,
5y ₂ , . . . 5y ₃₂ are provided as a second set of first optical path bending means, along the other vertical side 3Y′ of the tablet frame 3 and facing the mirrors 5y ₁ , 5y ₂ , . . . 5y _32. In total, 32 mirrors 5y' ₁ , 5y' ₂ , . . . 5y' ₃₂ are provided as a second set of second optical path bending means.

The directions of these mirrors 5 are set so that the laser light emitted from the laser light source 1 and reflected by the rotating polygon mirror 2 is further reflected twice and is incident on the photodetector 4.

That is, when the rotating polygon mirror 2 rotates counterclockwise and the laser beam reflected from the rotating polygon mirror 2 hits the mirror 5x ₁ , this laser beam is reflected by the mirror 5 x ₁ and the laser beam travels in the vertical direction. Become light and face
5x′ ₁ and enters the photodetector 4. The laser beam sequentially reflected from the rotating polygon mirror 2 is reflected by the mirror 5x _o (n=
2, 3, . . . 32 (the same applies hereafter) and similarly enters the photodetector 4 via the opposing mirror _5x'o .

After the laser beam hits the mirror _5x32 , the next surface of the rotating polygon mirror 2 appears. When the laser beam reflected from the rotating polygon mirror 2 hits the mirror _5y1 , it becomes a laser beam that travels in the horizontal direction, and enters the photodetector ₄ via the opposing mirror 5y'1. Sequentially, the laser beam hits the mirror 5y _o and enters the photodetector 4 via the opposing mirror 5y' _o . When the laser beam passes through the mirror 5y ₃₂ ,
The laser beam reflected from the rotating polygon mirror 2 directly enters the photodetector 4.

Here, the mirror 5 is realized by arranging many small planar mirrors, and the small planar mirrors 5x ₁ , 5x ₂ , ..., 5x ₃₂ and 5y ₁ , 5y ₂ , ...,
5y ₃₂ may be replaced by a parabolic mirror that connects the focal point to the rotating polygon mirror 2. Also a small plane mirror 5x′ ₁ ,
5x′ ₂ , . . . , 5x′ ₃₂ and 5y′ ₁ , _5y ′ ₂ , .

In this way, the laser beam scans the inside of the tablet frame 3 by the rotation of the rotating polygon mirror 2 at a constant angular velocity, and then enters the photodetector 4.

The characteristic configuration of the present invention is that the timing at which the photodetector 4 does not detect the incident light when an obstacle is placed inside the tablet frame 3 and the laser light scanning inside the tablet frame 3 is blocked by the obstacle is determined. The purpose of this method is to detect the coordinates of an obstacle by calculating .

FIG. 2 is a diagram showing a situation in which an obstacle is placed within the tablet frame of the device according to the present invention and the laser light incident on the photodetector is blocked.

In the figure, by rotating the rotating polygon mirror 2 counterclockwise with respect to an obstacle 7 placed at an arbitrary point,
First, the laser beam _L1 hits. Then laser L ₂ mirror 5x ₂₉
hit via. Next, the laser beam _L3 is sent out from the next surface of the rotating polygonal mirror 2 and impinges on it via the mirrors _5y3 and _5y'3 . Furthermore, the laser beam L ₄ impinges via mirrors 5y ₂₉ and 5y' ₂₉ . Therefore, among the laser beams sent out from the laser light source 1 and reflected by the rotating polygon mirror 2, the laser beams L ₁ , L ₂ , L ₃ , and L ₄ are as follows:
The light does not enter the photodetector 4 because of the obstacle 7.

FIG. 3 is a configuration diagram of a circuit for pulsing the incident light of the photodetector 4 of the apparatus according to the embodiment of the present invention.

In the figure, the output of the photodetector 4 is connected to the input of a binarization circuit 9 via an amplifier 8.
The incident light is pulsed. The output of this binarization circuit 9 is connected to a binarization output terminal 10. Therefore, the binary output terminal 10 outputs "1" when the laser beam is incident, and "0" when the laser beam is not incident.
The signals appear clearly distinguishable from each other. That is, when the obstacle 7 is placed within the tablet frame 3, an intermittent signal appears at the output of the photodetector 4.

FIG. 4 shows the binarization output terminal 10 shown in FIG. 3 when the rotating polygon mirror 2 of the apparatus according to the embodiment of the present invention rotates.
This is an operation time chart of the electrical signal waveform that appears in .

In the figure, time T from time t ₀ to t ₉ is the time during which the laser beam scans inside the tablet frame 3 and enters the photodetector 4 via the mirror 5 . O ₁ is the first
As shown in the figure, it is the electric signal of the laser beam incident on the photodetector 4 when no obstacle 7 is placed in the tablet frame 3, and O ₂ is the electric signal of the laser beam incident on the photodetector 4 when the obstacle 7 is not placed in the tablet frame 3. This is the same electrical signal when the is placed.

First, if there is no obstacle, detection of the laser beam that hits mirror 5x ₁ in FIG. 1 and is reflected starts at time _t1 . When the detection of the laser beam continues until time _t4 , the next surface of the rotating polygon mirror 2 appears and the laser beam is reflected from the mirror.
Detection of the laser beam is interrupted for a time t′ _s until it hits 5y ₁ .

Next, detection of the laser beam reflected by the mirror 5y ₁ is restarted at time t ₅ and continues until time t ₈ when the laser beam is reflected by the mirror 5y ₃₂ . From time t ₈ to t ₁₁ is the time for switching from mirror 5y ₃₂ to mirror 5x ₁ , but from time t ₉ to t ₁₀ the laser beam is directly incident on photodetector 4 from rotating polygon mirror 2.

Next, when there is an obstacle, in addition to the above operation, the laser beam _L1 is reflected from the rotating polygon mirror 2 at time t2 as shown in FIG. ₂ , and the laser beam L1 is reflected at time _t3 . ₂ is reflected and the laser light is blocked for t _s time, respectively. The laser light is similarly blocked at times _t6 and _t7 .

With such a configuration, if the rotating polygon mirror 2 rotates at a constant angular velocity and the laser beam is reflected in proportion to this, the time at which light is blocked by the obstacle 7 within the tablet frame 3 can be determined.

The present invention calculates the coordinates of the obstacle by paying attention to the fact that this light-blocking time is proportional to the rotation angle of the laser beam.

FIG. 5 is a block diagram of a calculation device for calculating the coordinates of an obstacle in the apparatus according to the embodiment of the present invention.

In the figure, 12 and 13 are logic circuits, 14 is a processing device, 15 is a coordinate display device, and other symbols correspond to the symbols in FIGS. 1 to 3, respectively.

The binary output terminal 10 is connected to the logic circuits 12 and 1.
Connected to 3. This logic circuit 12 is a logic circuit for calculating the light blocking time when the obstacle is not on the diagonal line of the tablet frame 3 connecting the rotating polygon mirror 2 and the photodetector 4. Further, the logic circuit 13 is a logic circuit for calculating the light blocking time when the obstacle is on the diagonal line. These logic circuits 12
and 13 are connected to a processing device 14, respectively. Processing device 14 includes logic circuits 12 and 1
3 is calculated and the result is displayed on the coordinate display device 15.

FIG. 6 is a detailed configuration diagram of the logic circuit 12 shown in FIG. 5, and FIG. 7 shows the center pulse detection circuit 16 and the logic circuit 13 shown in FIG.
FIG. 8 and 9 show this logic circuit 12 and center pulse detection circuit 1.
6 is an operation time chart. Each reference numeral in FIGS. 8 and 9 is an electric signal waveform diagram of the points indicated by the x marks in FIGS. 6 and 7 and each terminal.

Center pulse detection circuit 16 in FIGS. 6 and 7
, 17 is an input terminal connected to the binarized output terminal 10 shown in FIGS. 3 and 5. In FIG. The signal waveform at _two points input from this input terminal 17 becomes a signal delayed by the delay circuit 18 at point A, and at point B, a signal of the logical sum of the inverted signal at _two points O and the inverted signal at point A. Therefore, at point C, the output signals of the delay circuit 19 and the RS flip-flop circuit 20 are obtained. Furthermore, at point D, the signal at point C and
O A signal is obtained from the NOR of the signals at _two points. This signal at point D is a signal for determining the center pulse of the synchronization signal that determines the starting point of the light-blocking time of the device of this embodiment.

Next, the operation of detecting this central pulse will be explained. First, the signal waveform at point D is expanded. CLK
At the point the output signal of the clock oscillator 22 appears.
At point E, a logical sum signal of the inverted signal at point D and the signal at point CLK is obtained, and at point F, the rising signal at point E, which is the JK flip-flop circuit 2, is obtained.
3 output signals are obtained. Further, at point G, a Q output signal of the RS flip-flop circuit 24 is obtained, which uses the logical sum of the inverted signal at point E and the signal at point F as a set input, and uses the signal at point D as a reset signal. Further, at the terminal _S1 , a signal is obtained which is the logical sum of the signal at point E, the inverted signal of the signal at point G, and the inverted signal at point F.

In the center pulse detection circuit 16 of FIG. 7, the logical sum of the signal at the C terminal and the inverted signal at the D terminal is used as a set signal, and the logical sum of the signal at the C terminal and the signal at the D terminal is used as a reset signal. A signal obtained by ORing the Q output signal of the flip-flop circuit 27 and the signal at the _S1 terminal is obtained at the _STB1 terminal. this
The signal appearing at the STB ₁ terminal becomes the central pulse, and a one-cycle strobe is obtained from the device of this embodiment.

Further, at _one CLR point shown in FIG. 6, a signal that clears the counters 28 to 32 is obtained as the logical sum of the signal at point E, the inverted signal at point G, and the signal at point F.
Furthermore, at the H point of the input signal of the counter 28, a signal is obtained that is the logical sum of the signal at the D point and the signal at the CLK point.
When a signal of "1" appears at the STB ₁ terminal, the counter 28 sends the count number of one cycle counted so far to the processing device 14 (not shown) via the T ₀₁ terminal.
Send to a register within. After sending the count number to the register, the counter 28 starts counting the next cycle of strobes in response to a reset signal from the CLR ₁ point.

Next, in FIGS. 6 and 9, in order to find the time when the laser beam is blocked by an obstacle, O ₂
The signal at point I is obtained by inverting the signal at point I. At point J, a rising signal at point I is obtained by the JK flip-flop circuit 34. Further, at point K, a rising signal at point J is obtained by the JK flip-flop circuit 35.

At the _S2 terminal, a logical sum signal of the inverted signals at the _O2 point, J point, and K point is obtained, and a reset signal for the counters 31 and 32 is obtained.

In the center pulse detection circuit 16 of FIG. 7, the signal at the _S2 terminal and the RS flip-flop circuit 27
A signal obtained by ORing with the Q output signal of is obtained at the STB ₂ terminal. The signal appearing at this STB ₂ terminal indicates the time at which the mirror 5x ₃₂ shown in FIG. 1 is switched to the mirror 5y ₁ .

Further, at the L point, the input signal of the counter 29 is obtained as the logical sum of the signal at the CLK point and the signal at the K point. This counter 29 counts pulses from the time the central pulse is sent until the first time the light is interrupted.
The count number corresponding to the time t ₀₁ is sent to the terminal T ₁ . Furthermore, at point M, point CLK, point K, and J
Counter 30 as the logical sum of the signals of each point
The input signal is obtained. This counter 30 counts from the time when the center pulse is sent until the second time the light is blocked, and sends out the count corresponding to time _t02 to the terminal _T2 .

Next, in order to obtain the third and fourth light-blocking times, at point N, the JK flip-flop circuit 36 obtains a rising signal at point _O2 . Further, at point O, a rising signal at point N is obtained by the JK flip-flop circuit 37. Further, at point P, the input signal of the counter 31 is obtained as the logical sum of the signal at point CLK and the signal at point O. After receiving the reset signal from the _S2 terminal, this counter 31 counts from the time when the light is interrupted for the third time until the next central pulse is sent out, and outputs the count corresponding to time _t03 to the terminal T. Send to ₃ . Furthermore, at point Q,
The input signal of the counter 32 is obtained as the logical sum of the signal at the CLK point, the signal at the O point, and the inverted signal at the N point. After receiving the reset signal from the _S2 terminal, this counter 32 counts from the time when the light is interrupted for the fourth time until the next central pulse is sent out, and outputs the count corresponding to time _t04 to the terminal T. Send to ₄ .

Next, a detailed configuration diagram of the logic circuit 13 shown in FIG. 7 will be explained with reference to an operation time chart of the same circuit shown in FIG.

The logic circuit 13 is a circuit for calculating the light blocking time when an obstacle is on the diagonal line of the tablet frame 3 connecting the rotating polygon mirror 2 and the photodetector 4. Also, as shown in FIG. 9, the point at which the laser beam is reflected on the diagonal line cannot be set as the center pulse.

Therefore, the logic circuit 13 is a mirror 5x ₃₂ shown in Figure 1.
The configuration is such that a signal for determining the center pulse is obtained at the time of switching from mirror 5y1 to mirror _5y1 .

The operation of this logic circuit 13 is similar to that of the logic circuit 12.
The counter 39 outputs the number of pulses counted from the time when the center pulse is transmitted until the light is interrupted to the terminal _T5 . Also counter 40
When a signal of "1" appears at the STB ₃ terminal of the _center pulse detection circuit 16 in FIG. Send to a register within.

In this way, the terminals of logic circuits 12 and 13
STB ₁ , STB ₂ , STB ₃ , T ₀₁ , T ₀₂ , and T ₁ ~
Each signal is sent to the processing device 14 via _T4 .

FIGS. 11 to 13 are diagrams for deriving arithmetic expressions for the processing device 14 based on numerical values obtained from each of the above-mentioned signals. 11 and 12 are diagrams when the obstacle 7 is not on the diagonal line of the tablet frame 3 connecting the rotating polygon mirror 2 and the photodetector 4, and FIG. 13 is a diagram when the obstacle 7 is not on this diagonal line. FIG.

In Figure 11, θ ₁ and θ ² are the diagonal and the second
This is the angle formed by the laser beams _L1 and _L2 shown in the figure. Since the rotating polygon mirror 2 rotates at equal speeds, θ ₁ and θ ₂ are t 01 and t ₀₁ shown in the time chart of FIG.
t corresponds to ₀₂ hours respectively.

Therefore, θ ₁ =k t ₀₁ (1) θ ₂ =k t ₀₂ (2) (where k is the rotational angular velocity).

These laser beams L ₁ and L ₂ are transmitted to the tablet frame 3.
They intersect at two points, points P ₁ and P ₂ . Therefore point P ₁
For, tan(α−θ ₂ )=x ₁ /Ly (3) tan(α−θ ₁ )=x ₂ /Ly=x ₁ /y ₁ (4) (where α is the diagonal line of the tablet frame and the vertical line (Ly is the vertical distance between the rotating polygon mirror 2 and the photodetector 4, x ₁ and y ₁ are the x, y coordinates of point P ₁ , and x ₂ is the x coordinate of point P ₂ ). .

Also, regarding point P _2, tanψ ₁ = Lx−x ₁ /Ly=Lx−x ₂ /Ly−y ₂ (5) (where, ψ ₁ is the angle between the laser beam L ₂ passing through point P ₂ and the vertical line, Lx is the horizontal distance between the rotating polygon mirror 2 and the photodetector 4, _{and y2} is the y-coordinate of the point _P2 .

According to equations (3) and (4), x ₁ = Ly・tan (α−θ ₂ ) (6) x ₂ = Ly・tan (α−θ ₁ ) (7) y ₁ = Ly・x ₁ /x ₂ = Ly・tan(α−θ ₂ )/tan(α−θ ₁ )
(8) is obtained, and from equations (5) to (7), Ly−y ₂ =Ly・Lx−x ₂ /Lx−x ₁ =Ly・Lx／Ly−tan(α−
θ ₁ )/Lx/Ly−tan(α−θ ₂ ) Therefore, y ₂ =Ly{1−Lx/Ly−tan(α−θ ₁ )/Lx−Ly−tan(
α−θ ₂ )} Here, by Lx/Ly=tanα (9), y ₂ =Ly・tan(α−θ ₁ )−tan(α−θ ₂ )/tanα−tan
(α−θ ₂ )(10) is obtained.

Equations (6), (7), (8), and (10) are (X, y) of the intersection P ₁ and P ₂
This is an equation that gives coordinates, and the constant α can be calculated using equation (9), and θ ₁ and θ ₂ can be calculated using equations (1) and (2). therefore the intersection
The coordinates of P ₁ and P ₂ can be determined from the rotational angular velocity k and t ₀₁ and t ₀₂ .

That is, is obtained.

Next, in Figure 12, points obtained in the same way
The coordinates of P ₃ and P ₄ will be described. θ ₃ and θ ₄ are the angles formed between the diagonal and the laser beams L ₃ and L ₄ shown in FIG. In this case as well, since there is no change in the rotational direction of the rotating polygon mirror 2, θ ₃ and θ ₄ correspond to times t ₀₃ and t ₀₄ shown in the time chart of FIG. 9, respectively.

Therefore, θ ₃ =k t ₀₃ (11) θ ₄ =k t ₀₄ (12) holds true.

These laser beams L ₃ and L ₄ also touch the tablet frame 3.
They intersect at two points, points P ₃ and P ₄ . Therefore, tanβ=Ly/Lx (13) tanψ ₂ =Ly−y ₄ /Lx=Ly−y ₃ /Lx−x ₃ (14) tan(β−θ ₃ )=y ₄ /Lx (15) tan(β− θ ₄ )=y ₃ /Lx=y ₄ /x ₄ (16) (where β is the angle between the diagonal of the tablet frame and the horizontal line, x ₃ and y ₄ are the coordinates of point P ₃ , x ₄ and y ₄
is the coordinate of point P ₄ , and ψ ₂ is the angle between the laser beam L ₄ passing through point P ₃ and the horizontal line).

Comparing Equations (11) to (16) above with Equations (1) to (5) and (9) above, the coordinates of points P ₃ and P ₄ can be immediately obtained by replacing the variables shown below. Can be done.

α→β, Lx→Ly, Ly→Lx, θ ₁ →θ ₄ , θ ₂ →θ ₃ ,
x ₁ →y ₄ , y ₁ →x ₄ , x ₂ →y ₃ , y ₂ →x ₃ Therefore, the coordinates of points P ₃ and P ₄ are determined as follows.

Among the points P ₁ , P ₂ , P ₃ and P ₄ obtained in this way, the desired obstacle coordinates can be obtained as P ₁ = P ₃ or P ₂ = P ₄ , and if rounding errors due to calculation are ignored, , the intersection with one of the matching coordinates becomes the coordinates of the desired obstacle.

Next, the case where there is an obstacle on the diagonal line in FIG. 13 will be explained.

In the figure, 5M is the end of the mounted mirror 5, θ ₅ is the laser beam L ₅ passing through the point P ₅ of the obstacle 7 on the diagonal line, and the laser beam passing through the point P ₅ of the obstacle 7 on the perpendicular line. The angle between L ₅ and the vertical line, and γ, is the angle between the line connecting the rotating polygon mirror 2 and the mirror end 5M and the vertical line. This θ ₅ is shown in the time chart in Figure 10.
Corresponds to t ₀₅ hours.

Therefore, θ ₅ =k t ₀₅ +γ holds true.

Also, from tanβ=Ly/Lx=y ₅ /x ₅ tanθ ₅ =x ₅ /Ly, As, the coordinates of point _P5 can be found.

The constants γ, Lx, Ly, and the total angle θ that the laser beam can swing by the rotating polygon mirror 2 used in the above calculation equations are physical constants specific to the device of this embodiment, so the processing device It can be stored in the constant memory in 14.

Therefore, the coordinates of the obstacle 7 located at any position within the tablet frame 3 can be calculated in real time by the processing device 14 and taken out. This output can be displayed on the coordinate display device 15 and can be used as an input signal for other devices.

Although the number of mirrors in this embodiment is 32 in both the vertical and horizontal directions, it is not limited to this. Furthermore, although a rotating polygon mirror is shown as an example of the light beam bending means, a rotating prism may also be used.

FIG. 14 is a basic configuration diagram of a device according to a second embodiment of the present invention, in which the mirror 5 in FIG. 1 is replaced with a mirror surface 6 that diffusely reflects one of the two opposing sides as shown in the figure. The principle of this obstacle position detection method can also be applied.

〔Effect of the invention〕

As described above, according to the present invention, the coordinates of any obstacle within the tablet frame can be easily detected by calculating the interruption time of the laser beam scanning within the tablet frame. There is. The device of the present invention can be used on any plane other than a CRT screen, and can be used with any type of obstruction.

The device of the present invention can be used in a wide range of fields, including tablets on CRTs, electronic whiteboards, kanji input keyboards, menu input tablets, and ball trajectory measurement in ball games.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing how the laser beam is blocked. FIG. 3 is a block diagram of the pulsing circuit of the photodetector. Figure 4 is an operation time chart of the photodetector. FIG. 5 is a configuration diagram of the obstacle coordinate calculation device. FIG. 6 is a detailed configuration diagram of the logic circuit. FIG. 7 is a detailed configuration diagram of a concentric pulse detection circuit and a logic circuit. Figure 8-1
Figure 0 is an operation time chart of the same logic circuit and center pulse detection circuit. FIGS. 11 to 13 are diagrams for deriving arithmetic expressions for the processing device. FIG. 14 is a basic configuration diagram of an apparatus according to a second embodiment of the present invention. 1... Laser light source, 2... Rotating polygon mirror, 3...
Tablet frame, 4... Photodetector, 5... Mirror, 6...
... Mirror surface, 7 ... Obstacle, 8 ... Amplifier, 9 ... Binarization circuit, 10 ... Binarization output terminal, 12, 13
... logic circuit, 14 ... processing device, 15 ... coordinate display device, 16 ... central pulse detection circuit, 17 ...
...Input terminal, 18...Delay circuit, 20...RS flip-flop circuit, 22...Clock oscillator,
23...JK flip-flop circuit, 24, 27
...RS flip-flop circuit, 28, 29, 3
0, 31, 32...Counter, 34, 35, 3
6, 37...JK flip-flop circuit, 39,
40...Counter.

Claims (1)

[Claims] 1. A light source 1, and a rotary bending means 2 for bending the output light of this light source.
and arranged on one side of two opposing sides of the four sides surrounding the coordinate plane on which the obstacle 7 whose position is to be detected exists, and output light of the rotary bending means according to the rotation angle of the rotary bending means. a first optical path bending means for bending the light to form parallel bent light corresponding to the coordinates on the coordinate plane; and a photodetector 4 disposed at the same point, wherein the first bending means and the second optical path bending means are provided. two sets 5x, 5x', 5y, 5y' are arranged on four sides so as to surround the coordinate plane, and are equipped with an arithmetic device that calculates the position of the obstacle on the coordinates from the intermittent output of the photodetector. An obstacle position detection method characterized by: 2. The light source is a laser light source, the rotating bending means is a rotating polygon mirror, and the first optical path bending means and the second optical path bending means are:
The obstacle position detection method according to claim 1, which is a Fresnel mirror in which a large number of plane mirror pieces are arranged on a straight line.