JPH0115086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate detection method in a coordinate input device, and more particularly to an improvement in a coordinate detection method using a resistive sheet type coordinate detection device.

One type of computer input device is a coordinate input device commonly called a touch panel.

A touch panel is constructed by superimposing a coordinate detection device on a display, and when you touch an input item displayed on the display with your finger, the coordinate detection device detects the coordinate position at that time. Since the desired input can be made using the keyboard, the input operation is much simpler than that of conventional keyboards, and it has recently begun to be used more frequently.

The main methods used in this touch panel coordinate detection device include a switch matrix method, an optical method, and a resistive sheet method.

The switch matrix type coordinate detection device is
A transparent panel with band-shaped transparent electrodes arranged at a predetermined pitch in the Y direction and a transparent panel with band-shaped transparent electrodes arranged at a predetermined pitch in the Y direction are placed so that the electrode surfaces face each other and there is a slight gap between them. When you press lightly with your finger on the desired input item displayed on the display, the flexible upper panel deforms and connects the nearby X- and Y-direction electrodes. makes contact, and this contact point is detected as the coordinates of the indicated point.

Therefore, the detection coordinates are limited to the intersections of the electrode matrix, which has the disadvantage of poor resolution.Furthermore, the device is constructed of two panels, and the upper panel deforms when giving instructions, making it difficult to see what is displayed on the display. It also has the disadvantage of being inferior in terms of ease.

Further, an optical coordinate detection device uses a 1:1 pair of a light emitting element and a light receiving element, and forms a plurality of optical signal lines at a predetermined pitch in the X and Y directions on the top of the display. The coordinate position of the indicated point is detected based on the position of the optical signal line that is interrupted when the display is touched with a finger.As with the switch matrix method described above, the detected coordinates are limited to the intersections of the optical signal line matrix, so the resolution is low. It has the disadvantage of being inferior to

On the other hand, a resistive sheet type coordinate detection device consists of a hard panel made of glass or the like with a transparent resistive film coated on its entire surface, and current flows from the four sides of the panel to the indicated point on the resistive film. Since the coordinate position of the indicated point is detected by the ratio, it is possible to detect the coordinates of all points on the resistive film, and it is far superior to the former in terms of resolution.

In addition, since the panel is hard and does not deform during instruction, it is easy to see and has the advantage of being easy to manufacture.

For these reasons, the resistive sheet type coordinate detection device is attracting the most attention, and there is a strong demand for the development of a means to reduce the detection errors that conventionally occur in this type.

[Conventional technology]

The configuration of a conventional resistance sheet type coordinate input device is shown in a schematic plan view of FIG.

In the same figure, P is an input panel formed of a resistor sheet, SW1X, SW2X, SW1Y, SW2
Y is analog switch, e is AC power supply, A _x ,
A _1-x is a current measuring device, ADC is an A/D converter,
MPU is a microcomputer that performs control and calculations, S _XY is the switch control signal line, X _TO is the instruction operating point, C is the human body ground capacity, _OUT
GND indicates the grounding point.

In such a configuration, when pointing (touching) the X _TO point with a finger or a light pen, the coordinates of the X _TO point in the X direction are the same as the analog switch SW1X.
Detected when only SW2X is turned on.

In other words, at this time, from the X _TO point, the analog switch SW
For example, the resistance values up to 1X and SW2X are R _x and R _1-x
Then, the analog switches _{SW1X and}
The currents flowing through SW2X are I _x and I _1-x , respectively.

Therefore, these current values are converted into A/D converter.
The ADC converts it into a digital signal, and the microcomputer MPU performs calculations to determine the X coordinate x of the X _TO point.

X=I _1-x / (I _x + I _1-x ) Also, regarding the Y coordinate y of the indicated operation point X _TO ,
Obtain in the same manner with only SW1Y and SW2Y turned on.

In the coordinate detection device, the analog switch needs to have high reliability, and a semiconductor switch such as a MOS transistor is usually used.

In this case, there is an ON resistance in the analog switch, so the following shows the indicated coordinates X, current amount I _x , and
For the reason explained using FIG. 3 showing the relationship of I _{1 -x} , the above-mentioned conventional configuration has the disadvantage that an accurate pointing point cannot be detected.

In the same figure, R _s is the input panel (resistance sheet)
resistance, R _1x and R _2x are analog switch SW1X
and the ON resistance of SW2X, X _T is the indicated coordinate, X _TO is the indicated point, and l is the panel length.

In other words, if there is no ON resistance of the analog switch, the relationship between the indicated coordinates and the above-mentioned current amount is a linear function, as shown by the chain line B in the same figure, and has linearity, so the coordinates of the indicated point can be detected accurately. However, in reality, the ON resistance of analog switches SW1X and SW2X
Since R _1x and R _2x exist, the current amount decreases due to these, resulting in curves as shown by solid lines A ₁ , A _s , and A ₂ .

Here, A ₁ is a straight line showing the decrease in the amount of current due to the ON resistance of SW1X, A ₂ is the decrease in the amount of current due to the ON resistance of SW2X, and A _s is the decrease in the amount of current due to the resistance of the panel sheet.

Therefore, for example, when I _x = 0.5, I _1-x = 0.5 indicates the center position of the panel 0.5 (X _TO ) which should be detected, for example, I _x = 0.51, I _1-x = 0.49. The coordinates of the indicated point are 0.49 as shown by X _TO ′.
The output is shifted from the indicated coordinates.

Furthermore, as mentioned above, in analog switches using semiconductor devices, the temperature coefficient of the resistance is large, so the ON resistance changes greatly due to changes in ambient temperature, and from this point as well, coordinates that deviate from the indicated coordinates are output. Ru.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is the detection error of the indicated coordinates caused by the ON resistance of the analog switch and the change in the ON resistance due to the ambient temperature.

[Means for solving problems]

The solution to the above problem is to use a coordinate input panel in which a resistive film is provided on a substrate, and when an instruction operation is made at one point on the resistive film, the amount (for example, current,
a conversion circuit for converting and outputting (voltage, frequency, time, phase, etc.), a switch means for selectively connecting the conversion circuit and the X and Y ends of the resistive film, and calculating a conversion output value and outputting designated coordinates. When detecting indicated coordinates by a coordinate detection device having an arithmetic output circuit, the coordinate detection device is equipped with a circuit that can perform a pseudo-indication operation on a plurality of fixed points on the panel side end of the switching means or on the panel resistive film. and detects the coordinates of the fixed point by performing a pseudo instruction operation on the fixed point by the pseudo instruction operation circuit in a state where it is recognized that there is no instruction operation on the input panel, and detects the coordinates of the fixed point. This is accomplished by the coordinate detection method according to the present invention, which uses the coordinates of a point as a reference value and uses the reference value in calculations to obtain indicated coordinates.

[Effect]

That is, the present invention performs a pseudo instruction operation on the panel side end of the switch means or the input panel resistive film,
By determining the coordinate values at or near the connection point between the switch resistance and the input panel, and using this value as a reference value in the calculation to obtain the indicated coordinates (X, Y), accurate This allows detection of indicated coordinates.

〔Example〕

The present invention will be specifically explained below with reference to an embodiment shown in FIG.

In the figure, a is a schematic plan view showing the configuration of a coordinate detection device used in the method of the present invention, and b is a diagram of the relationship between detected coordinates X and current amounts I _x and I _1-x in the coordinate detection method of the present invention. It is.

In Figure 1, 1 and 2 are pseudo instruction operation circuits, P is an input panel coated with a resistive film such as tin oxide, SW1X, SW2X, SW1Y, SW2Y are analog switches, and e is an AC power supply A _x , A _{1 -x} is a current measuring device, ADC is an A/D converter, MPU is a microcomputer that performs control and calculations, S _XY is a switch control signal line, X _T is an instruction operating point, C is human body ground capacity, _OUT , GND is the grounding point, A ₀ and A ₁ are the pseudo instruction operation points, SW3 and SW4 are the switches for pseudo instruction operation, C ₀ and C ₁ are the capacitors, S _AO and S _A1 are the pseudo instruction signal lines, and X is the detection coordinate , 1 is the panel length, (I _x ) ₀ and (I _1-x ) ₀ are the current at point A ₀ , (I _x ) ₁ and (I _1-x ) ₁ are the current at point _A , (I _x ) _T and (I _1-x ) _T indicate the amount of current at the indicated point X _T.

In the embodiment shown in the figure, the connection point between the input end of the analog switch and the two diagonal vertices of the resistor panel is
A ₀ and A ₁ are used as pseudo-instruction operating points.

Doing this means that the pseudo instruction operating point A ₀
There is an advantage that _A1 can be used for both X and Y coordinate detection.

In the coordinate detection device used in the method of the present invention, as _shown in _{FIG .} and A ₁ respectively, and when it is recognized that there is no instruction operation, by turning on SW3 and SW4 respectively by the pseudo instruction operation signal, pseudo instruction operation is applied to A ₀ point and A ₁ point, respectively. It is configured so that it can be done.

When detecting the X coordinate of the instruction operation point X _T , it is recognized that there is no instruction operation, and the analog switches SW1
Turn on. At this time, the capacitor C ₀ is connected to the pseudo instruction operation point A ₀ on the panel P, and it becomes as if an instruction operation is performed at this point, and the current amounts (I _x ) ₀ and (I _1-x ) ₀ are measured. Then, the coordinate x ₀ of the A ₀ point is determined by the calculation: X ₀ = (I _1-x ) ₀ / {(I _x ) ₀ + (I _1-x ) ₀ }.

Next, after turning off SW3, switch SW4
is turned on, the current amount (I _x ) ₀ and (I _1-x ) ₀ are measured, and the calculation of X ₁ = (I _1-x ) ₁ / {(I _x ) ₁ + (I _1-x ) ₁ } is performed. _{The coordinates X 1 of} point A can be found by

The coordinates of X ₀ and X ₁ are then stored as reference values.

_{Next ,} when _{a pointing} operation is performed _{at point} I _1-x ) _T } Furthermore, the coordinates of the reference point stored in advance X ₀ ,
Using X ₁ , the calculation of X=(X _T -x ₀ )/(x ₁ -x ₀ ) is performed, and the coordinates X of the instruction operating point _XT normalized with respect to x ₀ and x ₁ are output.

Also analog switches SW1X, SW2X
OFF and SW1Y, SW2Y ON, calculate and store the Y-direction coordinates y 0 , _{y 1} of the reference points A ₀ , A ₁ using the same method as described above, and then use the indicated point X _T in the instruction operation. When detecting the Y coordinate of
Using the values of y ₀ and y ₁ , perform the same calculation as above to obtain y ₀ , ₁
Outputs the Y coordinate of the indicated operating point X _T normalized with respect to

Thus, in this embodiment, the connection points A ₀ and A ₁ between the input panel P and the analog switches SW1X and SW2X on the input panel (resistance sheet) P
Since the coordinates x ₀ and x ₁ of are normalized as a reference, the accurate coordinates of the instruction operation can be detected regardless of the ON resistance of the analog switch.

Furthermore, by frequently performing the pseudo instruction operation between instruction operations, the coordinates of the reference point at a temperature approximately equal to that at the time of the instruction operation can be determined, thereby eliminating detection errors caused by the temperature characteristics of the analog switch.

〔Effect of the invention〕

As explained above, according to the resistance sheet type coordinate detection method of the present invention, the coordinates of the indicated operating point are detected regardless of the ON resistance of the analog switch and its temperature characteristics, so the coordinate detection accuracy is greatly improved. ,
The performance and reliability of the coordinate input device are improved.

[Brief explanation of drawings]

FIG. 1a is a schematic plan view showing the configuration of a coordinate detection device used in the method of the present invention, and FIG. 1b is a diagram showing the detected coordinates X, current amount I _x , and
Figure ₂ is a schematic plan view showing the configuration of a conventional resistor sheet type coordinate input device, Figure 3 is a diagram showing the relationship between the detected coordinates X and the amount of current I _x in the conventional coordinate detection method.
and I _1-x . In the figure, 1 and 2 are pseudo instruction operation circuits, P
is the input panel, SW1X, SW2X, SW1Y,
SW2Y is an analog switch, e is an AC power supply,
A _x , A _1-x are current measuring devices, ADC is A/D converter, MPU is microcomputer, S _XY is switch control signal line, X _TO is indicated operating point, C is human body ground capacity, OUT _XY is coordinate output , GND is the ground point, A ₀ and A ₁ are pseudo instruction operation points, SW3 and SW4 are pseudo instruction operation switches, C ₀ and C ₁ are capacitors,
S _AO and S _A1 are pseudo instruction operation signal lines, X is the detection coordinate, 1 is the panel length, (I _x ) ₀ and (I _1-x ) ₀ are the current amount at point A ₀ , (I _x ) ₁ and ( I _1-x ) ₁ is the amount of current at _one point of A, (I _x ) _T
and (I _1-x ) _T indicates the amount of current at the indicated point X _T.

Claims (1)

[Claims] 1. A coordinate input panel provided with a resistive film on a substrate;
a conversion circuit that converts and outputs a quantity related to the designated coordinate point when a specified operation is made at one point on the resistive film; a switch means that selectively connects the conversion circuit and the X and Y edges of the resistive film; When detecting designated coordinates by a coordinate detection device having a calculation output circuit that calculates an output value and outputs designated coordinates, the coordinate detection device is provided with a plurality of fixing points on the panel side end of the switching means or on the panel resistive film. A circuit that can perform a pseudo instruction operation on a point is added, and the pseudo instruction operation circuit performs a pseudo instruction operation on the fixed point in a state where it is recognized that there is no instruction operation on the input panel. A coordinate detection method characterized by detecting the coordinates of a fixed point, using the coordinates of the fixed point as a reference value, and using the reference value in calculation for obtaining indicated coordinates. 2. The coordinate detection method according to claim 1, wherein two diagonal vertices of a quadrilateral effective coordinate area are selected as the fixed points. 3. The coordinate detection method according to claim 1, wherein the pseudo instruction operation is performed sequentially at a predetermined time period.