JPH0553717A - Optical two-dimensional coordinate input device - Google Patents

Abstract

PURPOSE:To provide an optical two-dimensional coordinate input device which secures the high coordinate detecting accuracy without requiring any complicated adjustment. CONSTITUTION:A cursor 2 is movably placed on a planar member 1 which regulates a two-dimensional coordinate surface and designates the input coordinates. The cursor 2 has a function to recurrently reflect the scanning beams in parallel to the two-dimensional coordinate surface. A pair of optical units 3 and 4 are arranged over the two-dimensional coordinate surface with a space secured between them. Each of both units 3 and 4 includes a fixed light source and angularly scans the light beams of the light source to produce two canning beams crossing to each other. At the same time, each optical unit receives the recursive light beams to measure the deflection angle of the corresponding recursive light beam based on each light source beam. A calculation part 8 is connected to a pair of the units 3 and 4 and calculates the two-dimensional coordinate value of the input coordinates based on the data on the measured deflection angle and with the use of a prescribed coordinate calculation formula. Furthermore a setting part 9 connected to the optical unit pair optimizes previously the coordinate calculation formula by simulation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical two-dimensional coordinate input device for manually inputting image information and the like using a light reflection type cursor.

[0002]

2. Description of the Related Art As an optical two-dimensional coordinate input device, one based on the principle of triangulation as shown in FIG. 7 has been conventionally known. A coordinate input device of this type is disclosed in, for example, Japanese Patent Laid-Open No.
It is disclosed in Japanese Patent No. 5805. As shown in the figure, the conventional optical coordinate input device includes a pair of optical units 101,
102 and a light-reflecting cursor 103. A laser light source 104 is housed in one of the optical units 101, and the emitted laser beam emits a rotating mirror 105.
Is scanned angularly by and a scanning beam is emitted in parallel with the coordinate area. The other optical unit 102 has the same configuration and emits the second scanning light beam so as to intersect with the first scanning light beam. The pair of scanning light rays are recursively reflected by the cursor 103 having a cylindrical mirror surface and travel backward. The backward light is received and detected by the light receiving element built in each optical unit. The optical unit 101 is based on this received light detection,
Angle θ1 formed by the laser beam and the beam traveling backward from the cursor
To measure. Similarly, the optical unit 102 also measures the angle θ2 formed by the laser beam and the beam traveling backward from the cursor 103. The distance between the rotation centers of the rotary mirrors provided in the pair of optical units 101 and 102 is set to L. Further, the laser light emitted from the laser light source 104 is set to be inclined by an inclination angle Δθ1 with respect to a straight line passing through the distance L in advance. This is due to design reasons. Similarly, the laser light emitted from the other laser light source is also set to be tilted by the tilt angle Δθ2. As is clear from the illustrated geometrical relationship, the two-dimensional coordinates x and y of the point P designated by the cursor 103 can be calculated from the distance L, θ1-Δθ1 and θ2-Δθ2 according to the principle of triangulation. .. For example, when the rotation center O of the rotary mirror 105 is set as the coordinate origin, the input coordinate values x and y are given by the following formulas 1 and 2.

[Equation 1]

[Equation 2] This calculation is performed by the calculation unit 106 including a computer or the like.
Executed by.

[0003]

As is apparent from the geometrical configuration shown in FIG. 7, in order to accurately obtain the input coordinate values based on the principle of triangulation, the center of the rotating mirror serving as the reference point is determined. It is necessary to make the laser beam incident accurately. Conventionally, for example, a CCD camera has been used to align the axis of the laser beam, but it requires skill and unavoidable error. In addition, it is necessary to fix the distance L between the pair of reference points and to perform accurate measurement in advance. Therefore,
Conventionally, a frame made of a special metal material having an extremely small coefficient of linear thermal expansion is used to fix the pair of optical units, which is expensive. Further, for example, when a large coordinate input device having a length of 2 m and a width of 6 m is produced, the measurement error of the distance L needs to be about 0.01 mm in order to obtain the coordinate detection accuracy of about ± 0.5 mm. Generally, it is difficult to achieve such measurement accuracy. Further, it is necessary to precisely measure the above-mentioned tilt angles or offset angles Δθ1 and Δθ2. This angle measurement requires extremely strict accuracy, and for example, in order to achieve the above-described coordinate detection accuracy, an error of 0.001 degree or less is allowed.

As described above, the conventional optical two-dimensional coordinate input device based on the principle of triangulation contains various error factors that cannot be controlled, and is large in size of 2 m in length and 6 m in width. There is a problem that it is difficult to achieve the coordinate detection accuracy ± 0.5 mm generally required in the market in the coordinate input device. Further, there has been a problem that in order to reduce the coordinate detection error as much as possible, it is inevitable that the measurement work or the adjustment work for a long period of time requires an extremely high skill in advance.

In view of the above problems of the prior art, it is an object of the present invention to provide an optical two-dimensional coordinate input device which does not require accurate axis alignment of a laser beam and does not require angle or distance parameter measurement. To aim.

[0006]

Means adopted for solving the above-mentioned problems of the prior art and achieving the object of the present invention are as follows. That is, the optical two-dimensional coordinate input device according to the present invention includes, as basic components, a plane member that defines a two-dimensional coordinate surface, a light reflection type cursor, and a pair of optical units. The cursor is movably placed on the two-dimensional coordinate plane for designating input coordinates, and has a function of recursively reflecting a scanning light beam parallel to the two-dimensional coordinate plane. In addition, the pair of optical units each include a fixed light source that is arranged apart from each other on the two-dimensional coordinate plane. The light source beam emitted from each fixed light source is angularly scanned by a rotating mirror or the like to generate two intersecting scanning light beams. In addition, each retroreflected ray reflected by the cursor is received, and the deviation angle of the corresponding retroreflected ray with respect to each source ray is measured. As a characteristic element of the present invention, a calculation unit and a setting unit are provided. The calculation unit calculates a two-dimensional coordinate value of the input coordinate by using a predetermined coordinate calculation formula based on the measured values of the pair of declinations.
Further, the setting unit is adapted to optimize the coordinate calculation formula in advance by simulation.

[0007]

According to the present invention, the two-dimensional coordinate value of the input coordinate is calculated based on the measured value of the pair of declination angles using a predetermined coordinate calculation formula. This coordinate calculation formula is set as a form optimized in advance by simulation. In other words, it is given as a result of absorbing and canceling various error factors included in the hardware configuration of each coordinate input device. Therefore, unlike the conventional structure based on the principle of triangulation, precise measurement of each parameter and optical axis alignment are not required at all. Then, the deviation angle itself formed by the light source beam such as the laser beam and the retroreflected beam can be measured extremely accurately by the optical unit. In this way, since the two-dimensional coordinate value of the input coordinate is calculated based on only the deflection angle data that can be precisely measured, only the arithmetic error occurs and the coordinate detection accuracy is remarkably improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing the basic configuration of an optical two-dimensional coordinate input device according to the present invention. As shown in the figure, the present apparatus includes a plane member 1 that defines a two-dimensional coordinate plane. The plane member 1 is made of a plotter sheet or the like in which squares are swung with high accuracy, has an accuracy of about 0.1 mm, and has dimensions of 2 m in length and 6 m in width. A cursor 2 is movably arranged on the two-dimensional coordinate plane, and has a function of recursively reflecting a scanning light beam parallel to the two-dimensional coordinate plane. The input coordinates are designated by aligning the center point P of the cursor 2 with a desired position. The pair of optical units 3 and 4 are arranged above the two-dimensional coordinate plane so as to be separated from each other. A fixed light source 5 including a laser oscillator and the like is housed in the right optical unit 3. Further, it is provided with a reflecting mirror 6 which rotates at a constant speed around a predetermined rotation axis M1, and continuously reflects the light source light beam emitted from the fixed light source 5 to generate a scanning light beam. In addition, it includes a light receiving element for receiving the retroreflected light rays reflected by the cursor 2 and traveling backward. With this configuration, the optical unit 3 measures the angle 2 × θ1 formed by the light source ray and the retroreflected ray or the deviation angle θ1. The optical unit 4 on the left side also has the same configuration, and the light source beam emitted from the fixed light source 15 is continuously reflected by the reflecting mirror 16 rotating about the rotation axis M2, and the first scanning light beam described above. Generate a second scanning ray that intersects. The declination angle θ2 formed by the retroreflected light reflected by the cursor 2 and the light source light is measured. In this device, it is not necessary to accurately align the optical axis of the light source beam emitted from each fixed light source with the rotation axis of the reflecting mirror. Further, it is not necessary to accurately measure the distance between the rotation axes of the pair of rotating mirrors, and it is not necessary to obtain accurate parallelism with respect to the X axis of the two-dimensional coordinate plane.

A calculator 8 including a computer is connected to the pair of optical units 3 and 4, and the input coordinate P 2 is calculated using a predetermined coordinate calculation formula based on the measured values of the pair of deflection angles θ1 and θ2. Calculate dimensional coordinate values. Furthermore, the setting unit 9
Is provided, and the coordinate calculation formula is optimized in advance by simulation. That is, the optimization is performed in such a manner that various error factors included in the optical units 3 and 4 are absorbed in each parameter of the coordinate calculation formula.

The operation of the optical two-dimensional coordinate input device shown in FIG. 1 will be described in detail with reference to FIG. FIG. 2 is a geometrical optical diagram for explaining the operation of the right optical unit. The operation of the left optical unit 4 can also be explained using the same ray diagram. First, the light source ray S emitted from the fixed light source 5 is represented by the linear equation shown in the following mathematical formula 3.

[Equation 3] It should be noted that it is convenient in the calculation later that the parameters x _m1 and y _m1 are introduced in the formula 3. Parameter x _m1 ,
y _m1 indicates the two-dimensional coordinates of the rotation axis M1 of the rotating mirror 6. Since the light source ray S passes through the reflection point R1 (x _r1 , y _r1 ), the following formula 4 is established.

[Equation 4]

Next, consider a straight line T passing through the reflecting mirror 6. Since this straight line T passes through the reflection point R1 and the rotation axis M1, its inclination is represented by the following mathematical expression 5.

[Equation 5]

The fact that this inclination is a function of the angle of deviation θ1 is calculated as follows. Note that θ1 is the light source ray S and the retroreflected ray U
It is half the value of the angle 2 × θ1 formed by. First, the rotation axis M
Consider a straight line V that passes through 1 and is orthogonal to the light source ray S. Since this straight line V is orthogonal to the light source ray S, its inclination is -1 / a. Therefore, the inclination angle formed by the straight line V and the X axis is represented by arctan (-1 / a). or,
The angle formed by the straight line V and the straight line T is equal to θ1. This relationship can be easily derived by using the law of reflection established between the light source ray S and the retroreflected ray U. Since the angle formed by the straight line V and the straight line T is θ1, the angle formed by the straight line T and the X axis is represented by θ1 + arctan (−1 / a). Therefore, the slope of the straight line T previously expressed in Equation 5 can be obtained as in Equation 6 below.

[Equation 6]

Finally, let us consider the recursive ray U passing through the reflection point R1 and the input coordinate point P. Recursive ray U is reflection point R
Since it passes through 1 and the coordinate point P, its inclination is given by the following Equation 7.

[Equation 7] Note _{x p} and _{y p} in Equation 7 represents a 2-dimensional coordinate values of the input coordinates P. The angle formed by the recursive ray U and the X axis is represented by the following formula 8.

[Equation 8]

On the other hand, the angle between the light source ray S and the X axis is ar
It is represented by ctan (a). Therefore, its complementary angle is π-a
It is represented by rctan (a). As is clear from the geometrical relationship of FIG. 2, the angular relationship represented by the following mathematical formula 9 is established for the triangle defined by the light source ray S, the retroreflected ray U, and the X axis.

[Equation 9]

When the equations (4), (6) and (9) thus obtained are summarized and the variables x _r1 and y _r1 are deleted, the following equation (10) is finally obtained.

[Equation 10]

Similarly, the following formula 11 is obtained for the left optical unit 4 as well.

[Equation 11]

Equations 10 and 11 are input coordinate values x _p ,
The relationship between y _p and the pair of deflection angles θ1 and θ2 is shown.
θ1 and θ2 are numerical values obtained by actual measurement. Substituting the measured pair of deflection angle data into Equation 10 and Equation 11, x _p
The input coordinate values can be calculated by solving the simultaneous equations with respect to y and y _p .

By the way, the equation 10 includes four parameters a, b, x _m1 and y _m1 . a is the light source ray S
Is the slope of the straight line, and b is also the intercept b + a × x
These are parameters included in _m + y _m1 and x _m1 and y _m1 are two-dimensional coordinate values of the rotation axis M1 of the reflecting mirror 6. These parameters are optimally set in advance by simulation. The same applies to Formula 11. As an example, focusing on the equation (10), this can be regarded as a four-variable equation including four variables a, b, x _m1 and y _m1 . Therefore, the argument data is actually measured for four sample input coordinates whose coordinate values are known. By substituting the four sample coordinate value data and the corresponding measured deviation data into the mathematical expression 10, the variable a,
A four-dimensional simultaneous equation for b, x _m1 and y _m1 is obtained. The parameters a, b, x are solved by solving this four-dimensional equation using a subroutine built in the setting unit 9.
Optimal values of _m1 and y _m1 can be obtained.

Coordinate calculation formula (Formula 10,
When the optimization of Expression 11) is completed, the calculation unit 8 calculates the coordinates using the deviation data actually measured with respect to the unknown input coordinate values. That is, a two-dimensional simultaneous equation that gives unknown coordinate data x _p , y _p can be obtained by substituting the measured argument data into the equations 10 and 11.
The input coordinate value is obtained by solving this two-dimensional simultaneous equation by a subroutine incorporated in the calculation unit 8.

By the way, the accuracy of the optimized coordinate calculation formula depends on the selection of the four sample input coordinates. It is preferable to repeat the simulation in order to remove this dependency. For example, first, declination data is measured with respect to four known sample input coordinates arranged at equal intervals in parallel with the X axis, and the parameters of the coordinate calculation formula are temporarily calculated. Based on the tentatively calculated result, the coordinate value is actually calculated based on the deflection angle data measured for the other known plural coordinate points. The accuracy is evaluated by comparing the calculation result with the known coordinate value given to the input coordinate point. In this way, the provisional calculation of the parameters included in the coordinate calculation formula is repeated to finally fix the four specific sample input coordinates that give the optimum accuracy, and the parameter definite calculation is performed.

By the way, there is a possibility that the deviation data measured with respect to the finally fixed four sample input coordinates itself may contain an error. Therefore, it is preferable to perform an additional simulation to remove this error.
That is, each of the four sample input coordinates is slightly shifted,
Shake the measured declination data. In this process, the calculation of the input coordinate value is repeated to set the parameter with the highest accuracy over the entire two-dimensional coordinate area. When the calculation processing of the unknown input coordinates is actually performed using the coordinate calculation formula obtained in this way, the average accuracy is 0.
I was able to achieve about 15 mm.

Finally, specific examples of the optical unit and the cursor used in the present invention will be briefly described. FIG. 3 is a schematic diagram showing a configuration example of the right optical unit 3. The left optical unit has the same structure. The optical unit 3 is
It has a fixed light source 5, a reflecting mirror 6 that rotates at a constant angular velocity about the rotation axis M1, and a light receiving element 21 that receives the return light reflected by the cursor and returned and generates a detection signal. The light beam emitted from the fixed light source 5 is the half mirror 2.
After passing through 2, the light goes toward the vicinity of the rotation axis M1 of the reflecting mirror 6. At this time, the optical axis of the light beam of the light source does not necessarily need to coincide with the rotation axis. Here, the light source beam is scanned at a constant angular velocity, and when it crosses the central axis of the cursor, it is recursively reflected, moves backward, and returns to the reflecting mirror 6. Here, the half mirror 22 is further reflected.
After passing through the filter, the light is received by the light receiving element 21 including a photodiode. The light receiving element 21 outputs a detection signal in synchronization with the light receiving timing.

The reflecting mirror 6 is rotated at a constant angular velocity by the drive circuit 23. The drive circuit 23 outputs a timing pulse every one rotation cycle of the reflecting mirror 6. The timing pulse output from the drive circuit 23 and the detection pulse output from the light receiving element 21 are input to the waveform processing circuit 24, subjected to waveform processing, and then output from the output terminal. Since the output signal is output in accordance with the time interval at which the detection pulse is generated with reference to the timing pulse, the angle between the retroreflected ray and the light source ray is 2 from the point that the reflecting mirror 6 rotates at a constant angular velocity. It represents × θ1.

FIG. 4 is a perspective view showing an example of a cursor for inputting coordinates. The cursor 2 is composed of a cylindrical light reflecting member 25 having a central axis and a supporting member 26. Although not shown, inside the cylindrical light reflecting member 25, a sighting member having a hair cross mark whose intersection coincides with the axis of the cylinder is mounted. Support member 2 for a given coordinate plane
When the cursor 2 is arranged with the bottom surfaces of 6 in contact with each other, the central axis of the cylinder is arranged perpendicular to the coordinate plane. In this state, the support member 26 is gripped, and the coordinate point to be input is designated using the aiming member. Since the scanning light rays that are parallel to the coordinate plane and travel toward the central axis of the cylindrical reflecting member 25 are incident perpendicularly to the reflecting surface, they are reflected in the same optical path in opposite directions, and the retroreflected light rays are fixed light sources. Go back to. The main cursor 2 can be used on any coordinate plane as long as it is within the range of scanning light rays.

FIG. 5 is a block diagram showing an example of the electric circuit configuration of the optical coordinate input device according to the present invention. As described above, the coordinate input device is composed of the pair of optical units 3 and 4 and the computer 10 including the calculation unit 8 and the setting unit 9. The optical units 3 and 4 and the computer 10 are electrically connected to each other by a cable. The optical unit 3 includes a drive circuit 23 for rotating the reflecting mirror 6 at a constant angular velocity and a timing detection circuit 2 connected to the drive circuit 23.
Includes 7. The timing detection circuit 27 outputs the timing pulse A1 at a predetermined timing every time the reflecting mirror 6 makes one rotation at a predetermined period T, for example, at a timing when the normal line of the reflecting mirror 6 is parallel to the light source beam from the fixed light source 5. .. The light receiving element 21 is connected to the amplifier circuit 28, and the detection signal is amplified and then output as the detection pulse B1. The waveform processing circuit 24 includes the timing detection circuit 27 and the amplification circuit 2.
8 is connected to the received timing pulse A1
Also, the detection pulse B1 is subjected to waveform processing and an output pulse C1 is output. The output pulse C1 is generated in synchronism with the reception of the retroreflected ray coming from the cursor 2, and therefore is related to the angle 2 × θ1 formed by the source ray and the retroreflected ray. The other optical unit 4 also has a similar electrical configuration, and therefore its description is omitted. The computer 10 has a first counting circuit 29, counts the pulse interval of the output pulse C1 from the right optical unit 3, and calculates angle data θ1. The second counting circuit 30 is provided, and the pulse interval of the output pulse C2 from the left optical unit 4 is counted to calculate the angle data θ2. The calculator 8 is connected to these counting circuits 29 and 30 via interfaces 31 and 32. Calculator 8
Calculates a two-dimensional coordinate value of the input coordinate using a predetermined coordinate calculation formula based on the actually measured pair of angle data θ1 and θ2. Further, the setting unit 9 is also connected, and the coordinate calculation formula is optimized in advance by simulation. In this simulation, the known sample coordinate data input by the keyboard 14 and the actually measured angle data θ1,
It is performed based on θ2.

Finally, a method of measuring the deflection angle will be briefly described with reference to the timing chart of FIG. First, in the right optical unit 3, when the reflecting mirror 6 is rotated in the cycle T, the timing detection circuit 27 outputs the timing pulse A1 in the cycle T. At this time, the amplifier circuit 28 outputs the detection pulse B1 in synchronization with the light receiving time of the light receiving element 21.
The detection pulse B1 has a large peak and a subsequent small peak. The large peak occurs when the reflecting mirror 6 is positioned perpendicularly to the light source beam, is synchronized with the timing pulse A1, and is independent of the retroreflected light beam from the cursor 2. The subsequent small peak is synchronized with the timing when the retroreflected ray from the cursor 2 is received, and if it occurs t1 hours after the large peak, the time t1 is proportionally related to the angle data θ1 to be obtained. The waveform processing circuit 24 waveform-processes the timing pulse A1 and the detection pulse B1 and outputs an output pulse C1.

The same operation is performed in the left optical unit 4. In this case, the rotation period and the phase of the reflecting mirror coincide with those of the right side optical unit, so that the same timing pulse A2 is obtained. Further, the detection pulse B2 continues to have a small peak t2 hours after the large peak,
At this point, the retroreflected ray from the cursor 2 is received. An output pulse C2 is obtained based on the timing pulse A2 and the detection pulse B2, and the time interval t2 between adjacent large and small peaks is proportionally related to the angle data θ2 to be obtained.

Subsequently, the first counting circuit 29 outputs the output pulse C
The pulse time interval t1 of 1 is counted, and the angle data θ1 is obtained based on the following Expression 12.

[Equation 12] Further, the second counting circuit 30 counts the pulse time interval t2 of the output pulse C2, and obtains the angle data θ2 based on the following formula 13.

[Equation 13]

[0029]

As described above, according to the present invention, in a light reflection type two-dimensional coordinate input device using a pair of optical units and a light reflection type cursor, a pair of measured deflection angle data is used in advance. The input coordinates are detected using the optimized coordinate calculation formula. This coordinate calculation formula is optimized by simulation so as to minimize the error in the coordinate detection result in each coordinate input device. Therefore, there is an effect that the coordinate input accuracy is remarkably improved as compared with the conventional optical coordinate input device based on the principle of triangulation. Further, unlike the conventional method, there is no need to increase the positional accuracy of the light source and the reflecting mirror, so that there is an effect that a complicated adjustment work is not required and the cost of parts can be kept low. Furthermore, there is an effect that the coordinate calculation formula can be updated by regularly performing simulations, and maintenance can be easily performed against various fluctuation factors. Finally, since there is no restriction on the positional relationship between the pair of optical units 3 and 4, there is an effect that the present coordinate input device can be freely set in any two-dimensional coordinate area.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a basic configuration of an optical two-dimensional coordinate input device according to the present invention.

FIG. 2 is a diagram for explaining the basic principle of the optical two-dimensional coordinate input device according to the present invention.

FIG. 3 is a schematic diagram showing a configuration example of an optical unit.

FIG. 4 is a perspective view showing an example of a cursor.

FIG. 5 is a block diagram showing an electrical configuration example of an optical two-dimensional coordinate input device according to the present invention.

6 is a waveform diagram for explaining the operation of the circuit shown in FIG.

FIG. 7 is a schematic diagram showing a conventional optical two-dimensional coordinate input device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plane member 2 Cursor 3 Optical unit 4 Optical unit 5 Fixed light source 6 Reflector 8 Calculation part 9 Setting part 15 Fixed light source 16 Reflector

Claims (1)

[Claims] 1. A plane member for defining a two-dimensional coordinate plane and a recursive scanning ray parallel to the two-dimensional coordinate plane and movably mounted on the two-dimensional coordinate plane for designating input coordinates. Includes a cursor with a function of reflecting light in a vertical direction, and a pair of fixed light sources arranged apart from each other on a two-dimensional coordinate plane, and angularly scans each light source beam to generate two intersecting scanning light beams. A pair of optical units for measuring the deflection angle of the corresponding retroreflected ray with respect to each light source ray by receiving each retroreflected ray, and a predetermined coordinate calculation formula based on the measured value of the pair of deflection angles. An optical two-dimensional coordinate input device comprising a calculation unit for calculating a two-dimensional coordinate value of input coordinates using the setting unit and a setting unit for previously optimizing a coordinate calculation formula by simulation.