JPH0347530B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tilt correction method for a coordinate input device.

Conventionally, when a pattern such as characters or figures input on the input screen of a coordinate input device is sent to an output device (for example, an image display device or a graphic plotter) for reproduction and output, the output pattern is obtained at the desired position and size. Therefore, the electrical signal (coordinate signal) indicating the input pattern is subjected to origin position correction and size correction before being sent to the output device.

However, many coordinate input devices are of the type in which a piece of paper is placed on the input surface and input is made using a writing instrument on the paper surface, or of the type in which a transparent input surface is provided close to the output surface. In the former type, it is difficult to place the paper so that it is not tilted at all with respect to the assumed coordinate axes on the input surface, and in many cases, the output pattern is tilted with respect to the input pattern on the paper surface. Become. This inclination cannot be corrected by the origin position correction and size correction described above. Among the latter types, when using a rear projector that projects images from behind onto a screen, which is the output surface, it is difficult to ensure that the screen and rear projector are not tilted at all when installed. In many cases, there will be a difference in slope between the input pattern and the output pattern. This inclination also cannot be corrected by the origin position correction and size correction described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tilt correction method for a coordinate input device for correcting a tilt that cannot be corrected conventionally.

The method of the present invention receives X and Y coordinate signals indicating the X and Y coordinate values of input points to the coordinate input device, respectively, and multiplies the X and Y coordinate values by first and second coefficients to calculate the inclination of each coordinate axis. first and second variable coefficient means that generate first and second electric signals indicating the amount of correction, and are capable of varying and setting the first and second coefficients, respectively, when calibrating the tilt of each coordinate axis; the X coordinate signal and the second
The coordinate axis tilt is corrected by adding the electric signal of
The apparatus includes a first adding means for sending out a coordinate signal, and a second adding means for adding the Y-coordinate signal and the first electrical signal to send out a Y-coordinate signal whose coordinate axis inclination is corrected.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. Signals X and Y are coordinate signals sent from the coordinate input device, respectively, and are electrical signals indicating the X and Y coordinates of the input location on the input surface. That is, the signals x and y are analog signals in which each voltage has a value proportional to the X and Y coordinates of the input location. Amplifiers 4X and 4Y are both inserted and connected as buffers, and the voltages of the respective signals x and y are directly connected to variable resistors.
It is applied to one end of VRX and VRY, and signals -x and -y, which are obtained by inverting the polarity of the signals x and y, are applied to the other ends of variable resistors VRX and VRY via amplifiers 5X and 5Y. The amplifier 4X (or 4Y) is an amplification circuit with an amplification factor of 1, and for example, as shown in the figure, the voltage at the output terminal of the operational amplifier 14 may be directly connected as feedback to the input terminal. Amplifier 5X (or 5Y) is an amplification circuit with an amplification degree of -1, and for example, as shown in the figure, operational amplifier 1
It is sufficient to connect a resistor R in series to the input terminal of 5, and connect the voltage at the output terminal back to the input terminal via another resistor R. The variable resistor VRX (or VRY) is a poransiometer that allows you to manually adjust the voltage division ratio, and it
y) is provided to obtain a slope correction signal of an intermediate voltage. The slope correction signal sent from the variable resistor VRY (or VRX) is sent to one input terminal of the adder 6X (or 6Y). Adder 6
X (or 6Y) is an analog addition circuit,
The voltages of the above-mentioned slope correction signal and signal x (or y) are added, and a signal x _p (or y _p ) of the voltage of the addition result is sent out.

Obviously, the voltage of the signal x _p (or y _p ) is the linear combination of the voltages of the signals x and y. Coordinates (or Y
coordinates). Therefore, by adding and connecting the circuit of this embodiment to a coordinate input device, it is possible to add a new tilt correction function to the conventional origin position correction and size correction functions. That is,
When calibrating the initial input, the origin position is corrected by first inputting to the origin of the input surface and outputting to the origin of the output surface, and then adjusting the input surface's X axis (or Y
Adjust the variable resistor VRX (or VRY) manually so that the input is input to a predetermined point other than the origin on the output surface, and the output is on the X-axis (or Y-axis) on the Y-axis) tilt correction. Further, size correction between the input and output is performed at a predetermined full scale point to complete the initial calibration.
In the input mode after completion of this initial calibration, the coordinate signal is corrected for the origin position, size, and tilt by the circuit of this embodiment, so that an output pattern with the desired position and size and with the tilt removed with respect to the input pattern is obtained. can get.

By providing a tilt correction function that was previously unavailable, there is no need to spend a long time positioning the input surface so that it is not tilted with respect to the coordinate axes when placing paper on the input surface or installing a rear projector. After positioning within a short time, tilt correction can be easily performed. In addition, if you print each point for initial calibration on the input paper in advance, such as the origin, the calibration points on each coordinate axis, or the full scale point, you can avoid printing misalignment or tilting the input surface with respect to the coordinate axes. Even if the pattern is placed at a desired location, an initial calibration is performed before inputting, and an origin position correction, size correction, and tilt correction are performed to obtain an output pattern at a desired position and size and without tilt. Furthermore, initial calibration can also be performed very easily when a paper with a copy of the output pattern is placed directly on the input surface and a new pattern is inputted over the already output pattern.

The first embodiment shows a case where the initial calibration of tilt correction is performed manually, but an embodiment in which a means for automatically performing the initial calibration is provided in order to eliminate the trouble of performing the initial calibration manually is described below. explain.

FIG. 2 is a block diagram showing the second embodiment. In place of the variable resistors VRX and VRY of the first embodiment, variable resistors 7X and 7X, which are potentiometers that adjust the voltage division ratio according to the value of the digital signal, 7Y is used, and control circuits 8X and 8Y are provided to control the voltage division ratio of both.

FIG. 3 is a block diagram showing an example of the configuration of the control circuit 8X of this embodiment. The control circuit 8X is given a signal x _p from the adder 6X. The signal x _p is converted into a digital signal by an analog-to-digital converter (A/D) 12 and sent to one input terminal of a comparator 13 . The other input terminal of the comparator 13 is supplied with a digital signal indicating a zero value from the reference data generating circuit 18. The comparator 13 compares the values of the digital signals sent to both input terminals,
A pulse signal indicating the magnitude relationship between the two is generated and sent to the switch SW. The switch SW is a switch that is closed only during initial calibration of the Y-axis inclination. On the other hand, the gate circuit 20 starts sending a pulse train of the clock signal to the counter 19 at the start of the initial calibration of the slope of the Y-axis, and when the magnitude relationship of the pulse signal sent from the comparator 13 via the switch SW is reversed, the gate circuit 20 starts sending the pulse train of the clock signal to the counter 19. Signal pulse train counter 19
It has a gate function to stop sending to. The counter 19 is an up-down counter that counts up or down the pulse train of the clock signal so as to adjust the voltage division ratio of the variable resistor 7Y in the direction of reversing the magnitude relationship indicated by the pulse signal sent via the switch SW. It is. The digital signal indicating the count result value of the counter 19 is
It is sent to variable resistor 7Y. When the magnitude relationship of the pulse signals sent from the comparator 13 is reversed, the gate circuit 20 stops sending out the pulse train of the clock signal. After this time, the counter 19 continues to send out a digital signal holding the counter result when the pulse train is stopped. At this time, the value of the signal x _p obtained by digitally converting the signal x _p substantially converges to zero, and the initial calibration of the Y-axis tilt is completed.

The control circuit 8Y also has the same configuration as the control circuit 8X, and automatically controls the voltage division ratio of the variable resistor 7X so that the voltage of the signal _yp substantially converges to zero during the initial calibration of the X-axis tilt. adjust.

In the input mode, the switch SW is opened, the voltage division ratio of variable resistors 7X and 7Y maintains the value at the time of completion of the initial calibration of the tilt of both coordinate axes, and the signals x _p and y _p are subjected to tilt correction to the signals x and y. It becomes a signal.

FIG. 4 is a block diagram showing a third embodiment of the present invention. In this embodiment, signals Xo and Yo are sent out by performing tilt correction on signals X and Y obtained by digitally converting analog coordinate signals. signal
(or Y) is multiplier 17X (or 17Y)
and sent to adder 16X (or 16Y). Multiplier 17X (or 17Y) and adder 16X (or 16Y) are digital multipliers and adders, respectively. Multiplier 17
X (or 17Y) sends a digital signal sent from the control circuit 9Y (or 9X) to the adder 16Y (or 1
6X). Adder 16Y (or 16X)
is the digital signal sent from the multiplier 17X (or 17Y) and the signal Y (or X)
It sends out a signal Yo (or Xo) indicating the result of addition with
Send to X).

The control circuits 9X and 9Y each have a configuration in which the A/D 12 is removed from the control circuits 8X and 8Y of the second embodiment, and the other coordinate component with respect to the coordinate axis is substantially zero at the time of initial calibration of the tilt of each coordinate axis. The digital signal values sent to multipliers 17Y and 17X are automatically adjusted so that the values converge to .

In this embodiment, the analog signal processing circuit of the second embodiment is entirely constructed with a digital signal processing circuit, and it is obvious that it can also be realized in a configuration in which the circuit is operated under program control using a processor such as a microcomputer. It is.

As is clear from the above description, the present invention has the effect of realizing a tilt correction method for a coordinate input device that enables tilt correction, which was conventionally impossible to correct.

[Brief explanation of drawings]

1 to 4 are block diagrams showing embodiments of the present invention. 4X, 4Y, 5X, 5Y...Amplifier, VRX,
VRY, 7X, 7Y...Variable resistance, 6X, 6Y,
16X, 16Y... Adder, 17X, 17Y...
Multiplier, 8X, 8Y, 9X, 9Y...control circuit.

Claims (1)

[Claims] 1. Receiving X and Y coordinate signals indicating the X and Y coordinate values of input points to the coordinate input device, respectively, multiplying the X and Y coordinate values by first and second coefficients to obtain each coordinate axis. first and second indicating the amount of tilt correction;
first and second variable coefficient means that generate electric signals of the X coordinate signal and that can respectively vary and set the first and second coefficients when calibrating the inclination of each coordinate axis; a first adding means for sending an X-coordinate signal whose coordinate axis inclination is corrected by adding the Y-coordinate signal and the first electrical signal; and a Y-coordinate signal whose coordinate axis inclination is corrected by adding the Y-coordinate signal and the first electric signal
1. A tilt correction method for a coordinate input device, comprising: second addition means for sending out a coordinate signal. 2. The first and second variable coefficient means each include a comparison means that compares the value indicated by the output signal of the first and second addition means with a value of predetermined reference data, and During calibration, the first and second coefficients are varied so that the value of the sending signal converges to the value of the reference data in response to the comparison result of the comparison means, and after the convergence, the coefficients at the time of convergence are changed. 2. A tilt correction method for a coordinate input device according to claim 1, further comprising a control means provided with a coefficient generating means for holding the coefficient. 3. The tilt correction system for a coordinate input device according to claim 1, wherein the first and second variable coefficient means each have a variable resistance for varying the first and second coefficients. 4. The tilt correction system for a coordinate input device according to claim 3, wherein the variable resistor can be changed manually.