JPH027122A - touch coordinate input device - Google Patents

Abstract

PURPOSE:To detect contact position coordinates even with the quick touch by processing an impedance measurement and a position coordinate operation to use the impedance measured value during the previous contact in parallel. CONSTITUTION:A pair or above of terminals opposite to a resistance film is provided at a touch panel 18, the impedance viewed from one side terminal and the impedance viewed from other side terminal are measured by a microcomputer 44 and this is temporarily stored. The microcomputer 44 reads the impedance value measured before the contact of the instructed matter to the touch panel 18 and during the previous contact, from a memory at the idle time during the impedance measurement, operates the contact position coordinates and outputs the arithmetic result. Thus, since the impedance measurement and the output of the position coordinate operation and the arithmetic result of the previous contact are processed in parallel, the position coordinates of the quick touch can be also detected.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Fig. 5) Examples of means and actions for solving the problems to be solved by the invention (Figs. 1 to 4) Effects [Summary] Regarding touch coordinate input devices that measure the impedance seen from each terminal of a touch panel equipped with a resistive film to determine the coordinates of the touch position on the touch panel, the coordinates of the indicated position can be detected even if the touch is made quickly. With the aim of an impedance measuring means for measuring impedance and an impedance seen from the other terminal; and a touch position coordinate for calculating the coordinates of the touch position using the impedance measured before and during contact of the pointer with the touch panel. calculation means;
A touch coordinate input device having a touch coordinate input device including a memory for temporarily storing the measured impedance,
'l The coordinate calculation means reads the impedance measurement value during the contact surface and surface contact of the pointer to the touch panel during the idle time during the impedance measurement, performs the coordinate calculation, and calculates the calculation result. Configure to output.

1. Field of Industrial Application] The present invention relates to a touch coordinate input device that measures the impedance seen from the valley terminal of a touch panel provided with a resistive film to determine the coordinates of a touch position on the touch panel.

[Prior art] Figure 6 shows a conventional touch coordinate input device (Japanese Patent Laid-Open No. 60181
913) is shown.

A terminal R is provided at both ends of the resistor v410, and the terminal R is connected to the input terminal of the voltage follower 12 constituted by an operational amplifier, and the terminal R is connected to the output terminal of the voltage follower 12. , terminal R and terminal R are at the same potential. The finger 14 of the human body is placed at the pointing point P of the resistive film 101.
When brought into contact with each other, a current flows through the resistive film 10 from the terminal 1 and the terminal R toward the pointing point P, and both currents flow through the finger 14. Furthermore, the current flowing from the terminal rt to the indicated point P does not flow from the indicated point P to the terminal side because the input impedance of the voltage follower 12 can be regarded as infinite.

Therefore, the voltage between LP becomes equal to the voltage between RP, and the impedance seen from the terminal side is 5°, which is equal to the resistance film 10 between R and P is removed.Here, the resistance film 10 An insulating film is attached, and the combined impedance of the human body and this insulating film (herein simply referred to as the impedance or capacitance of the pointing object (including the human body)) can be approximated by the capacitance cB. Further, the resistance value of the resistive film IO is sufficiently smaller than this capacitance C8. Therefore, the impedance seen from the terminal side is the capacitance cx, and when calculating this capacitance cx under the above conditions, [n x=
Csx+ Go(R+-x/(Rx+ R+-x)
) ・ ・ (1) becomes.

, T1. x is the resistance value between LP of the resistive film 10, R+x is the resistance value between RP of the resistive film 10, and G! IX is the stray capacitance between the terminal and ground.

Terminal 17 is connected to the input terminal of variable oscillator 16, and variable oscillator 16 outputs pulses with a frequency inversely proportional to the capacitance value of the capacitor connected to this input terminal. Therefore, the capacitance Cx can be determined by counting the number N of pulses output from the variable oscillation 416 within a certain period of time and using the following formula (%). Also, the floating volume…
Since CSX is equal to Ca=O1, that is, the capacitance ff1cx of contacting the finger 14 with the resistive film IO, it can also be measured.

Next, Voltage Holo γ! 2 is connected to the terminal R, the output terminal of the voltage follower 12 is connected to the terminal R, the input terminal of the variable oscillator 16 is connected to the terminal R, and the output terminal of the voltage follower 12 is connected to the terminal R.
If the capacity Nc, -x seen from the side is measured, this C, -X becomes ('', l-X-Cs+-x+ CBARx/(Rx + R+-x)] (3).

here? CI]l-X is the stray capacitance between the terminal R and the ground.

If the position coordinate of point L is normalized to O and the position coordinate of one point is normalized to 1, the position coordinate X of indicated point P is expressed by the following equation.

x −n l−X/(RX+R+−x)
---(4) From the above formulas (+), (3), and (4), Rx
By eliminating 1R+ and C8 and finding the position coordinates X, the following equation is obtained.

X = (C+-x cs+-x)/[(cx C
5x)+ (C+-xC8l-X))
(5) According to this equation (5), the position coordinates X of the indicated point P can be determined without directly measuring the human body capacity.

A resistive film of a general touch panel is provided with a plurality of terminal pairs at opposing positions at the upper and lower ends and at opposing positions at the left and right ends, and the impedance seen from each terminal is measured in a time-sharing manner.

The position coordinate detection procedure consists of the following four steps.

■Measure the impedance seen from each terminal of the touch panel multiple times and find the average value.

■Determine the presence or absence of a touch from this average impedance value. If it is determined that there is a touch, (1) Measure the impedance seen from each terminal of the touch panel multiple times and find the average value.

(2) Using this average impedance and the above equation (5), calculate and output the contact position coordinates.

The reason why impedance is measured multiple times and the average value is used is to detect position coordinates with high accuracy.

[Problem to be solved by the invention] However, in order to reliably detect the coordinates of the indicated position, it is necessary to keep the finger in contact with the touch panel during the above steps 4. If j+n 'l' is too short, coordinate detection cannot be performed.4. Because of this, the problem is that it cannot respond to quick touches.
is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a touch coordinate input device that can detect the coordinates of a designated position even if a touch is made quickly.

[Means for Solving the Problem] In order to achieve this objective, the touch coordinate input device 4 according to the present invention includes the following components. .

(2) A touch panel in which a resistive film is arranged on a substrate and one or more pairs of opposing terminals are provided on the resistive film.

(2) An impedance measuring means for keeping both terminals of each pair at the same potential and measuring the impedance seen from one terminal and the impedance seen from the other terminal.

■Memory that temporarily stores the measured impedance.

■Touch position coordinates during idle time during impedance measurement, read the impedance measurement values measured before and during the previous contact with the pointer to the touch panel from the memory, calculate the touch position coordinates, and output the calculation results. calculation means.

[Operation] In the present invention, impedance measurement, position coordinate calculation using the impedance measurement value during the previous contact, and output of the calculation result are processed in parallel, so the minimum contact time for coordinate detection is shorter than before. The contact position coordinates are detected even with a quick touch.

[Example j An embodiment of the present invention will be described based on the drawings. .

Figure 1 shows the main structure of the touch coordinate input device when ij<t
,.

The touch panel 18 has a rectangular glass substrate coated with a 4-light resistive film, a SiOx film further coated thereon, and a resistive film FL4, f? +(
The same applies below 1-1-01. ) are formed by 4 pairs, and the ends FU+b are located at the opposite S j and Q positions of the upper and lower ends of the transparent resistive film.
D+ (i = l-m, the same applies hereinafter)/+ (formed as a pair).

The terminals RI, , R, 5tJt and DI are respectively A[1
It is connected to one end of each switch element constituting the switch arrays 20, 22, 24 and 26.

The other end of each switch element of analog switch arrays 20 and 24 is commonly connected to signal line Sl, and the other end of each switch element of analog switch arrays 22 and 26 is commonly connected to signal line S.

Hereinafter, for example, when the switch elements of the analog switch array 20.22 connected to the terminals L r Rl are closed, the terminal pair (Llltl) is said to be in a connected state.

The signal lines S, S, are connected to the signal lines S1, S, respectively via a changeover switch 28 having two interlocking switch elements.
It is switched and connected to S4 or signal line S6, S. This signal line S is a voltage follower 12 and a variable oscillator! The signal line S4 is connected to the input terminal of the voltage follower I2.
is connected to the output terminal of

The output pulses of the variable oscillation 416 pass through the AND gate 38 and are counted by the counter 40 when the AND gate 38 is opened by the output pulse of the mono-multi-by-break 36 . This mono multivibrator 36 is
As shown in FIG. 4, it is triggered at the falling edge of the trigger pulse from the timing generator 42. Further, after the count value of the counter 40 is read by the microcomputer 44 at the second rising of this trigger pulse, the counter 40
The count value is cleared by the microcomputer 44.

Timing generator 42 also provides select signals to analog switch arrays 20 and 22 via signal line S, and select signals to analog switch arrays 24 and 26 via signal line S and inverters 32 and 34, respectively. Then, a switch element drive pulse is supplied to the analog switch arrays 20 to 26 via the signal line S8. In these analog switch arrays 20 to 24, when the select signal is at a high level, any one of the switch elements is sequentially closed by a switch element drive pulse.

That is, the switch element is scanned by the switch element drive pulse. Therefore, the terminal pair (1,+,R,),
Any one of (Ul, D,) becomes connected sequentially.

This selector switch 28 is switched twice by a switching pulse supplied from the timing generator 42 via the signal line S7, as shown in FIG. 3, when the select signal is at a high level and when the select signal is at a low level. For each switch,
The switch elements of the selected analog switch arrays 20, 22 or 24, 26 are scanned by the switch element drive pulse. As shown in FIG. 4, a trigger pulse is output immediately after the switch element drive pulse.

These select signals, switch element drive pulses, and switching pulses are also supplied to the microcomputer 44, and the microcomputer 44 measures which terminal pair of the touch panel I8 is in the connected state and the impedance seen from which terminal side. Know what you are doing.

Next, referring to the timing chart shown in Figure 3.4,
The processing procedure of the microcomputer 44 shown in FIG. 2 will be explained.

In the initial state, the select signal is at high level and the analog switch array 20.22 is selected, the switching pulse is at low level and the changeover switch 28 is in the state shown in FIG. 1, and the terminal pair (LnSR,) is in the connected state. It is assumed that

(A) Initial processing procedure (100) Switch element drive pulse causes terminal pair (1,
,,R,) are connected, the count value of the counter 40 is cleared at the rising edge of the trigger pulse immediately after that, and the mono multivibrator 36 is triggered at the falling edge of this trigger pulse, and its output becomes high level. AND gate 38 is opened and pulses from variable oscillator 16 are counted by counter 40. The AND gate 38 is closed after a certain period of time, and the count value N of the counter 40 at this time is proportional to the reciprocal of the impedance seen from the terminal L1 side. At the next switch drive pulse, the terminal pair (1, 1, R,)
becomes connected, and the count value N of the counter 40 is read into the register at the rising edge of the trigger pulse immediately after that.
The counter 40 is cleared at the falling edge of this trigger pulse, and then the count value N stored in the register is used as a terminal.

The impedance seen from the side is calculated using the above equation (2) and stored in a memory (not shown).

Similarly, the impedance seen from the terminal 1, L, . . . side (L side) is measured and stored.

(102) Next, the changeover switch 28 is changed over by the changeover pulse, and the terminals R1 to R, are changed in the same manner as described above.

The impedance seen from the side (R side) is measured and stored.

(104, 106) Next, the select signal becomes low level and the analog switch arrays 24 and 26 are selected, and in the same manner as above, the terminals U, -U, side (U side), then ~
The impedance seen from the D side (D side) is measured and stored.

(111) If all of the stored impedances are below a certain value, it is determined that the finger 14 is not touched on the touch panel 18, and (113) the touch flag F
After is set to "0", the process returns to step 100.

When the finger 14 touches the touch panel 18, one of the stored impedances becomes a certain value or more,
It is determined in step Ill that there is a touch, and (112) the touch flag F is set to "■°," and then the process returns to step +00.

(B) Second and subsequent processing steps (101, 103, 105, 107) In the second and subsequent processing, during the free time in steps 100 to 106 above, the number of times temporarily stored in the memory or the The previous impedance measurements of Tadge Moe and Men and the above formula (
5) to calculate the locus fl(X, Y) of the indicated position.

In the free time at step 106, step 10
Part of the above calculation is performed in Step 7, and (108) When this coordinate calculation is completed, it is determined (+09) whether the touch flag F is °I", and if it is °1", that is, it is determined that the previous measurement was If the impedance obtained is that during the touch, (110) the obtained coordinates are output.

In this way, in the k-th process, the k-th impedance measurement, the coordinate calculation using the (k-1)th impedance measurement value, and the output of the results are performed in parallel, and the finger touch is quickly performed. It becomes possible to deal with this.

In addition, in the above embodiment, each side LS
Although the case where the impedance measurement is performed once for RSU and D has been described, it is of course possible to perform the measurement multiple times and use the average value of the measured values.

[Effects of the Invention] As explained above, according to the touch coordinate input device according to the present invention, one or more pairs of terminals facing the resistive film provided on the touch panel are provided, and both terminals of each pair are connected to the same potential. The impedance seen from one of the terminals and the impedance seen from the other terminal are temporarily stored in memory, and during free time during impedance measurement, before and before the pointer touches the touch panel. By reading the impedance measurement value measured during face-to-face contact from the memory, calculating the contact position coordinates, and outputting the calculation result, it is possible to perform impedance measurement, position coordinate calculation using the impedance measurement value during the previous contact, and its calculation. Since the result output is processed progressively, the minimum contact time during which coordinates can be detected is shorter than before, and it has the excellent effect of being able to detect the contact position coordinates even with a quick touch. .

[Brief explanation of the drawing]

1 to 4 relate to one embodiment of the present invention, in which FIG. 1 is a circuit diagram showing the main part configuration of a touch coordinate input device, FIG. 2 is a flowchart showing the processing procedure of the microcomputer 44, and FIG. FIG. 4 is a timing chart of the circuit shown in FIG. FIG. 5 is a circuit diagram showing the principle configuration of a conventional touch coordinate input device. In the figure, IO is a resistive film I2 is a voltage resistor, lower 16 is a variable oscillator, I8 is a touch panel, 0-26 is an analog switch array 28 is a changeover switch 32, 34 is an inverter 36 is a mono-multi-bi-break, 38 is an AND gate 40 is a counter 42 is a timing generator 44 is a microcomputer Processing procedure of the microcomputer 44 FIG.

Claims (1)

[Claims] A touch panel (18) in which a resistive film is arranged on a substrate, and one or more pairs of opposing terminals are provided on the resistive film, and both terminals of each pair are kept at the same potential, and one of the terminals is impedance measuring means (12, 16, 20 to 44) for measuring the impedance seen from the terminal and the impedance seen from the other terminal; a touch position coordinate calculation means (44) for calculating the coordinates of the touch position; and a touch coordinate input device comprising: a memory for temporarily storing the measured impedance, the touch position coordinate calculation means (44) , During the free time during impedance measurement, read the impedance measurement values before and during the previous contact of the pointer to the touch panel from the memory, calculate the coordinates, and output the calculation results (
44, 101, 103, 105, 107-110).