JP3107867B2 - Optical two-dimensional coordinate input device - Google Patents

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, a device based on the principle of triangulation has been conventionally known as shown in FIG. This type of coordinate input device is disclosed in, for example,
No. 5805. As shown in the figure, a conventional optical coordinate input device includes a pair of optical units 101,
102 and a light reflection type cursor 103. A laser light source 104 is housed in one optical unit 101, and the emitted laser beam is
Is scanned angularly, and a scanning light 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 beams are recursively reflected by the cursor 103 having the cylindrical mirror surface and travel backward. The backward light is received and detected by a light receiving element built in each optical unit. The optical unit 101 is based on this detection of light reception,
Angle θ1 between the laser beam and the light beam that has moved backward from the cursor
Is measured. Similarly, the optical unit 102 also measures the angle θ2 between the laser beam and the beam that travels backward from the cursor 103. The distance between the centers of rotation of the rotating 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 tilted in advance by a tilt angle Δθ1 with respect to a straight line passing through the distance L. This is for design reasons. Similarly, the laser light emitted from the other laser light source is also set to be inclined by the inclination angle Δθ2. As is apparent from the illustrated geometric relationship, the two-dimensional coordinates x and y of the point P specified 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 rotating mirror 105 is set to the coordinate origin, the input coordinate values x and y are given by the following Expressions 1 and 2.

(Equation 1)

(Equation 2) This calculation is performed by the calculation unit 106 including a computer or the like.
Is executed by

[0003]

As is apparent from the geometrical configuration shown in FIG. 7, in order to accurately determine the input coordinate values based on the principle of triangulation, the center of the rotating mirror serving as a reference point is required. It is necessary to accurately input a laser beam. Conventionally, the alignment of the laser beam has been performed using, for example, a CCD camera. However, skill is required and errors cannot be avoided. In addition, it is necessary to fix the distance L between the pair of reference points and to measure the distance accurately in advance. Because of this,
Conventionally, a frame made of a special metal material having an extremely small linear thermal expansion coefficient was used to fix a pair of optical units, so that it was expensive. Further, for example, when a large coordinate input device having a length of 2 m and a width of 6 m is prepared, a measurement error of the distance L needs to be about 0.01 mm in order to obtain a 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-described tilt angles or offset angles Δθ1 and Δθ2. This angle measurement requires extremely strict accuracy. For example, an error of 0.001 degrees or less is allowed in order to achieve the above-described coordinate detection accuracy.

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

In view of the above-mentioned problems of the prior art, the present invention provides an optical two-dimensional coordinate input device which does not require accurate alignment of a laser beam and does not require measurement of angle and distance parameters. Aim.

[0006]

Means adopted to solve the above-mentioned problems of the prior art and achieve 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 planar member that defines a two-dimensional coordinate plane, a light-reflective cursor, and a pair of optical units. The cursor is movably mounted on a two-dimensional coordinate plane to specify input coordinates, and has a function of recursively reflecting a scanning light beam parallel to the two-dimensional coordinate plane. Further, each of the pair of optical units includes fixed light sources which are arranged separately from each other on a two-dimensional coordinate plane. Light source rays emitted from each fixed light source are angularly scanned by a rotating mirror or the like to generate two intersecting scanning rays. In addition, each of the return rays reflected by the cursor is received, and the deflection angle of the corresponding return ray with respect to each light source ray is measured. A calculation unit and a setting unit are provided as characteristic elements of the present invention. Calculator predetermined para based on measurements of a pair of deflection angle
A two-dimensional coordinate value of input coordinates is calculated using a coordinate calculation formula including a meter . Further, the setting unit optimizes the coordinate calculation formula in advance by simulation. Specifically
Is a pair of optical units, a two-dimensional coordinate of the input coordinates.
Optical or mechanical error factors that affect the accuracy of the benchmark
The setting unit absorbs the error factor or
Set the parameters so that they cancel each other, and
Perform optimization.

[0007]

According to the present invention, the two-dimensional coordinate values of the input coordinates are calculated based on the measured values 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, various error factors included in the hardware configuration of each coordinate input device are absorbed and canceled. Therefore, unlike the structure based on the conventional principle of triangulation, there is no need for precise measurement of each parameter and optical axis alignment. The deflection angle itself between a light source beam, for example, a laser beam and a return beam, can be measured very precisely by the optical unit. As described above, since the two-dimensional coordinate value of the input coordinates is calculated based only on the argument data that can be precisely measured, only the arithmetic error occurs, and the coordinate detection accuracy is significantly improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a 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 for defining a two-dimensional coordinate plane. The flat member 1 is made of a plotter sheet or the like in which the grids are wagged with high accuracy, has an accuracy of about 0.1 mm, and has a size of 2 m in length and 6 m in width. The 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 adjusting the center point P of the cursor 2 to a desired position. A pair of optical units 3 and 4 are arranged apart from each other above the two-dimensional coordinate plane. The right optical unit 3 houses a fixed light source 5 composed of a laser oscillator or the like. Further, a reflecting mirror 6 that rotates at a constant speed about a predetermined rotation axis M1 is provided. The reflecting mirror 6 continuously reflects a light source beam emitted from the fixed light source 5 to generate a scanning beam. In addition, it includes a light receiving element for receiving the retro-reflected light beam reflected by the cursor 2 and traveling backward. With such a configuration, the optical unit 3 measures the angle 2 × θ1 or the declination θ1 between the light source light beam and the return light beam. The left optical unit 4 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 θ2 between the retroreflected light beam reflected by the cursor 2 and the light source light beam is measured. In the present apparatus, 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 an accurate parallelism with respect to the X axis on the two-dimensional coordinate plane.

A calculation unit 8 composed of a computer or the like is connected to the pair of optical units 3 and 4, and the input coordinate P is calculated using a predetermined coordinate calculation formula based on the measured values of the pair of declinations θ1 and θ2. Calculate dimensional coordinate values. Further, the setting unit 9
Are provided, and the coordinate calculation formula is optimized in advance by simulation. That is, 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 be described using a similar ray diagram. First, the light source beam S emitted from the fixed light source 5 is represented by the following linear equation shown in Expression 3.

(Equation 3) It should be noted that the parameters x _m1 and y _m1 are particularly introduced in Equation 3 for the sake of later calculation. The 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 equation 4 is established.

(Equation 4)

Next, a straight line T passing through the reflecting mirror 6 is considered. Since the straight line T passes through the reflection point R1 and the rotation axis M1, the inclination is represented by the following equation (5).

(Equation 5)

It is calculated below that the inclination is a function of the argument θ1. Note that θ1 is the light source ray S and the recursive ray U
Is half of the angle 2 × θ1 formed by First, the rotation axis M
Consider a straight line V passing through 1 and orthogonal to the light source beam S. Since the straight line V is orthogonal to the light source beam S, its inclination is -1 / a. Therefore, the inclination angle between the straight line V and the X axis is represented by arctan (-1 / a). or,
The angle between 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 beam S and the recursive beam U. Now, since the angle between the straight line V and the straight line T is θ1, the angle between 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 by Expression 5 is obtained as in Expression 6 below.

(Equation 6)

Finally, consider a recursive ray U passing through the reflection point R1 and the input coordinate point P. Recursive ray U is reflected point R
1 and the coordinate point P, the 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 between the recursive ray U and the X axis is represented by the following equation (8).

(Equation 8)

On the other hand, the angle between the light source ray S and the X axis is ar
ctan (a). Therefore, its complement is π-a
It is represented by rctan (a). As is clear from the geometric relationship in FIG. 2, the triangle defined by the light source ray S, the recursive ray U, and the X axis has an angular relationship represented by the following Expression 9.

(Equation 9)

Equations 4, 6, and 9 obtained as described above are collectively arranged and the variables x _r1 and y _r1 are deleted to finally obtain the following equation 10.

(Equation 10)

Similarly, the following equation (11) is obtained for the left optical unit 4.

[Equation 11]

Equations (10) and (11) represent input coordinate values x _p ,
y _p and a pair of deflection angle .theta.1, represents the relationship between .theta.2.
θ1 and θ2 are numerical values obtained by actual measurement. The measured pair of declination data is substituted into Expressions 10 and 11 to obtain x _p
And it can be calculated input coordinates by solving the simultaneous equations for y _p.

Incidentally, equation (10) includes four parameters a, b, x _m1 and y _m1 . a is the light source beam S
Where b is the intercept b + a × x
_m + y _m1 is a parameter included in addition x _m1, y _m1 is 2-dimensional coordinate values of the rotation shaft M1 of the reflecting mirror 6. These parameters are optimally set in advance by simulation. The same applies to Expression 11. As an example, focusing on Expression 10, this can be regarded as a four-variable equation including four variables a, b, x _m1 and y _m1 . Therefore, declination 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 declination data into Equation 10, variables a,
A four-dimensional simultaneous equation for b, x _m1 and y _m1 is obtained. By solving this four-dimensional equation using a subroutine built in the setting unit 9, each parameter a, b, x
The optimum values of _m1 and y _m1 can be obtained.

The coordinate calculation formula (formula 10,
When the optimization of Expression 11) is completed, the calculation unit 8 performs coordinate calculation using the argument data actually measured for the unknown input coordinate value. That is, the unknown coordinate data x _p, two-dimensional simultaneous equation giving y _p obtained by substituting the actually measured deflection angle data to the equation 10 and equation 11.
By solving this two-dimensional simultaneous equation by a subroutine built in the calculation unit 8, an input coordinate value is obtained.

By the way, the accuracy of the optimized coordinate calculation formula depends on the selection of four sample input coordinates. It is preferable to repeat the simulation to remove this dependency. For example, first, declination data is measured for four known sample input coordinates arranged at equal intervals in parallel with the X axis, and parameters of a coordinate calculation formula are temporarily calculated. Based on the provisionally calculated result, a coordinate value is actually calculated based on declination data measured for a plurality of other known coordinate points. The calculation result is compared with a known coordinate value given to the input coordinate point to evaluate accuracy. In this way, the tentative calculation of the parameters included in the coordinate calculation formula is repeated, and the specific four sample input coordinates that provide the optimum accuracy are finally fixed and the parameters are fixedly calculated.

Incidentally, there is a possibility that the deviation data itself measured for the finally fixed four sample input coordinates may also include an error. Therefore, it is preferable to perform an additional simulation to eliminate this error.
That is, each of the four sample input coordinates is slightly shifted,
Let's move the measured declination data. In this process, the calculation of the input coordinate value is repeatedly performed, and a parameter having the highest accuracy over the entire two-dimensional coordinate area is set. When the unknown input coordinates are actually calculated using the coordinate calculation formula thus obtained, the average accuracy is set to 0.
It was possible to achieve about 15mm.

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 illustrating a configuration example of the right optical unit 3. Note that the left optical unit has the same configuration. The optical unit 3
It has a fixed light source 5, a reflecting mirror 6 which rotates at a constant angular velocity about the rotation axis M1, and a light receiving element 21 for receiving the returning light reflected by the cursor and returning to generate a detection signal. The light source beam emitted from the fixed light source 5 is a half mirror 2
2 and near the rotation axis M1 of the reflecting mirror 6. At this time, it is not always necessary to make the optical axis of the light source beam coincide with the rotation axis. Here, the light source beam is scanned at a constant angular velocity. When the light beam crosses the center axis of the cursor, the light beam is reflected recursively, moves backward, and returns to the reflecting mirror 6. The half mirror 22 is further reflected here.
After passing through the filter through the light receiving element 21, the light is received by the light receiving element 21 composed of a photodiode or the like. 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 a driving 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 output from an 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 2 formed by the recurring light beam and the light source light beam from the point that the reflecting mirror 6 is rotating at a constant angular velocity. × θ1.

FIG. 4 is a perspective view showing an example of a cursor for inputting coordinates. The cursor 2 includes a cylindrical light reflecting member 25 having a central axis and a supporting member 26. Although not shown, an aiming member having a hair cross mark whose intersection point coincides with the axis of the cylinder is mounted inside the cylindrical light reflecting member 25. Support member 2 for a given coordinate plane
When the cursor 2 is placed with the bottom surface of the cylinder 6 in contact, the center axis of the cylinder is placed 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. The scanning light beam that is parallel to the coordinate plane and proceeds toward the central axis of the cylindrical reflecting member 25 is perpendicularly incident on the reflecting surface, and is therefore reflected in the same optical path in the opposite direction. Go back towards. The cursor 2 can be used for any coordinate plane as long as it is within the range of the scanning light beam.

FIG. 5 is a block diagram showing an example of an electric circuit configuration of the optical coordinate input device according to the present invention. As described above, the present coordinate input device includes a pair of optical units 3 and 4, and a computer 10 including a calculation unit 8 and a 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 driving circuit 23 for rotating the reflecting mirror 6 at a constant angular velocity and a timing detecting circuit 2 connected thereto.
7 is included. 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 cycle T, for example, at a timing when the normal 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 an amplifier circuit 28, and the detection signal is amplified and output as a detection pulse B1. The waveform processing circuit 24 includes the timing detection circuit 27 and the amplification circuit 2
8 and the received timing pulse A1
And the detection pulse B1 is subjected to waveform processing to output an output pulse C1. Since the output pulse C1 is generated in synchronization with the reception of the recurring light beam coming from the cursor 2, it is related to the angle 2 × θ1 between the light source light beam and the recurring light beam. Since the other optical unit 4 has the same electrical configuration, the description thereof is omitted. The computer 10 has a first counting circuit 29, and counts the pulse interval of the output pulse C1 from the right optical unit 3 to calculate angle data θ1. It also has a second counting circuit 30, which counts the pulse interval of the output pulse C2 from the left optical unit 4 and calculates angle data θ2. The calculation unit 8 is connected to these counting circuits 29 and 30 via interfaces 31 and 32. Calculation part 8
Calculates a two-dimensional coordinate value of input coordinates using a predetermined coordinate calculation formula based on a pair of actually measured angle data θ1 and θ2. A setting unit 9 is also connected, and optimizes a coordinate calculation formula in advance by simulation. In this simulation, the known sample coordinate data input from the keyboard 14 and the actually measured angle data θ1,
This is performed based on θ2.

Finally, a method of measuring the argument 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 at a period T, the timing detection circuit 27 outputs a timing pulse A1 at the period 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 followed by a small peak. The large peak occurs when the reflector 6 is positioned perpendicular to the light source beam, is synchronized with the timing pulse A1, and is independent of the recurring light beam from the cursor 2. The subsequent small peak is synchronized with the timing at which the recursive light beam from the cursor 2 is received. If it occurs after t1 time from the large peak, the time t1 is proportionally related to the angle data θ1 to be obtained. The waveform processing circuit 24 performs waveform processing on 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 optical unit, so that the same timing pulse A2 is obtained. In addition, the detection pulse B2 has a small peak continued t2 hours after the large peak,
At this point, a recurring 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
One pulse time interval t1 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 angle data θ2 based on the following equation (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 pre-set based on a measured pair of deflection angle data. 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 of the coordinate detection result in each coordinate input device. For this reason, 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 operation is not required and the cost of parts can be reduced. Furthermore, the coordinate calculation formula can be updated by sequentially performing the simulation periodically, and there is an effect that maintenance can be easily performed even for various fluctuation factors. Lastly, 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 an arbitrary two-dimensional coordinate area.

[Brief description of the 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 a basic principle of an optical two-dimensional coordinate input device according to the present invention.

FIG. 3 is a schematic diagram illustrating 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 example of an electrical configuration of the optical two-dimensional coordinate input device according to the present invention.

FIG. 6 is a waveform chart for explaining the operation of the circuit shown in FIG. 5;

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

[Explanation of symbols]

 Reference Signs List 1 plane member 2 cursor 3 optical unit 4 optical unit 5 fixed light source 6 reflecting mirror 8 calculation unit 9 setting unit 15 fixed light source 16 reflecting mirror

Claims (1)

(57) [Claims] 1. A planar member for defining a two-dimensional coordinate plane, and a scanning beam parallel to the two-dimensional coordinate plane and movably mounted on the two-dimensional coordinate plane for designating input coordinates. And a pair of fixed light sources spaced apart from each other on a two-dimensional coordinate plane. Each light source beam is angularly scanned to generate two intersecting scanning light beams. A pair of optical units for measuring the declination of the corresponding recurring ray with respect to each light source ray by receiving each recurring ray, and coordinates including predetermined parameters based on the measured values of the pair of declination angles An optical two-dimensional coordinate input device , comprising: a calculation unit for calculating a two-dimensional coordinate value of input coordinates using a calculation formula; and a setting unit for optimizing a coordinate calculation formula in advance by simulation . The pair of optical units Is the two-dimensional coordinate value of the input coordinates
Include optical or mechanical error factors that affect the accuracy of
The setting unit is configured to absorb or cancel the error factor.
Optimization of the coordinate calculation formula by setting parameters
And an optical two-dimensional coordinate input device.