JPH0433015A - Coordinate input means - Google Patents

Abstract

PURPOSE:To measure contact resistance together with a coordinate value at real time without increasing cost by reading the coordinate value just after impressing a voltage only at a high or low level to both of two resistance films, reading the coordinate value just after impressing the other voltage, and measuring the contact resistance by using these both values. CONSTITUTION:Before reading the coordinate value, only the voltage at the high or low level is impressed to both of two resistance films 1 and 2 and just after that, the coordinate value is read. Next, just after impressing the other voltage except for the preceding level to both of the resistance films 1 and 2, the coordinate value is read and by using the value read in advance and the value read later, the resistance value of the contact resistance at a contact part is measured. Namely, the resistance value of the contact resistance is measured by utilizing the fact of prolonging a time constant and generating large difference between the two read values when the contact resistance is high. Thus, without using any special writing tool, the resistance value to be changed with pen pressure can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coordinate input means for reading coordinates by detecting a potential on a resistive film, and relates to a means for measuring a contact resistance value that changes depending on pen pressure.

[Prior Art] Regarding conventional coordinate input means, there is a point at the tip of the writing pen.
A displacement measuring means having a displacement part supported by a spring is provided for measuring the writing pressure, and the writing pressure is measured by the output of the displacement measuring means.

[Problem to be solved by the invention 1 However, in the conventional technology, ■ it is necessary to prepare a special writing instrument for measuring pen pressure; ■ it is necessary to incorporate a pen pressure measuring means into the size of a normal writing instrument; This increases the cost and weight of the writing instrument. ■ Data transfer means or data storage means for transmitting or storing the measured value from the writing pressure measuring means must be built into the writing instrument, which increases cost and weight. In addition, when the transfer means is wired, there are problems such as a loss of usability.

The present invention is intended to solve these problems, and its purpose is to provide a coordinate input means for measuring a resistance value that changes depending on writing pressure without using any special marking equipment.

[Means for Solving the Problems] In order to solve the above problems, the coordinate input means of the present invention has the following features: a) 2. It has more than one electrode. two opposing resistive films; b) on the opposing resistive films;
C) means for applying two types of voltages, low level and high level, to the electrodes; C) means for disconnecting the electrodes from both of the two types of voltages to make them high impedance; and d) analog/digital conversion means. and e) applying a high-level voltage to one electrode with a resistive film on one side and a low-level voltage to the other electrode to create a voltage gradient on the resistive film and facing the resistive film. When the resistive film is made to have a high impedance and stress is applied to a certain point on the resistive film, the potential of the part that makes contact due to deflection is read from the electrode of the high impedance resistive film using analog/digital conversion means, and the contact is determined based on that value. In the coordinate input means for converting the position into numerical values: Apply the other voltage other than the above level to both of the two resistive films, immediately read the coordinate values, and use the previously read value and the later read value to determine the value of the contact area. It is characterized by measuring the resistance value of contact resistance.

[Function] By having the above configuration, the present invention can perform coordinate value reading after the resistance period and after charging the input capacitance of the analog/digital converter, and when reading coordinate values after discharging. The resistance value of the contact resistance can be measured by utilizing the fact that when the contact resistance is high, the time constant becomes long and a large difference occurs between the two read values.

[Example 1] Hereinafter, the present invention will be described in detail based on Examples. FIG. 1 is a circuit diagram of an embodiment of the coordinate input means of the present invention.

1 in the figure shows that when stress is applied in two directions to the - point, a uniform resistive film is formed on the underside of the elastically deformed plate, and a high level voltage is applied to collect current from the resistive film at both ends in the Y direction. A plate on which an application electrode (3 in the figure, hereinafter referred to as the Y-electrode) and a low-level voltage application electrode (4 in the figure, hereinafter referred to as the Y-electrode) are formed (
Hereinafter, it will be referred to as the upper resistance plate). 2 in the figure forms a uniform resistance film on the upper side of the plate material, and high-level voltage application electrodes (6 in the figure,
(hereinafter referred to as the X raw electrode) and the low-level voltage application electrode (5 in the figure)
, hereinafter referred to as the X-electrode) (hereinafter referred to as the lower claw plate).

7.8 in the figure shows P with a high level voltage connected to the emitter terminal.
NP h transistors Q3 and Q2, 9.10 in the figure are NPNI transistors Q3 and Q4 whose emitter terminals are connected to a low level voltage. Each transistor is in a cut-off state (11, 12, 13, 14 in the figure) by the control output (11, 12, 13, 14 in the figure) of the programmable controller section (21 in the figure, hereinafter abbreviated as PCU).
(hereinafter referred to as OFF) or saturated state (hereinafter referred to as ON)
It operates so that it is in one of the following states. Y raw electrode is Ql
, the X electrode is connected to the collector terminal of Q2, the Y-electrode is connected to Q3, and the X-W electrode is connected to the collector terminal of Q4. Each transistor is O
When the voltage is N, a voltage at the level connected to the emitter terminal of the transistor is applied to each electrode, and when each transistor is turned off, it is cut off from the voltage at the level.

Reference numerals 15 and 16 in the figure are analog switches SWI and 8w2, each of which is controlled by the control output (17 and 18 in the figure) from the PCU. SW1 and SW2 are analog/digital converters (19 in the figure) that selectively change the potential of the positive resistance plate and the lower claw resistance plate.
) is conductive to the input. In addition, the input impedance of the analog/digital converter is sufficiently large compared to the resistance of the resistance plate or the contact resistance between the resistance plates, and the SWI,
The potential of the resistor plate does not change depending on the conduction of SW2.

In the figure, 20 is an interface between the analog/digital converter and the PCU, and the PCU reads out the potential converted into a numerical value via the interface, and also controls the operation of the analog/digital converter, such as stopping and starting. .

In the figure, 22 is an interface between the PCU and other devices, and the PCTJ outputs coordinate data through this interface.

The control procedure performed by the PCU will be explained below according to the flowchart in section 2.3.4.

FIG. 2 is an outline of the control procedure of the coordinate input means of the present invention. First, read the X coordinate (step 1), then check whether the x value is an error or not.Step 2) If it is an error, read the X coordinate again.

If the value is normal, then read the Y coordinate (step 3)
), determine whether the Y value is an error or not. Step 4) If it is an error, restart from reading the X coordinate. If the value is normal, the contact resistance value R measured when reading the X coordinate
The average value of the contact resistance values Ry measured when reading the x and Y coordinates is stored in R. Step 5) The coordinate values (X, Y) and the average value of the contact resistances fly! Outputs H (step 6). Repeat this operation thereafter.

FIG. 3 is a flowchart of the X coordinate reading procedure.

Q1 and Q2 are turned OFF and Q3 and Q4 are turned ON to release the charges on the upper and lower resistive plates and bring the potential to a low level voltage (step 6). Turn on Q2 and Q4 to cause a voltage gradient to flow through the lower claw resistance plate, and turn off Ql and Q4 to cut off the positive resistance plate from each voltage (again, step 7), and start analog/digital conversion. (Step 8). When stress is applied to the positive resistance plate and it contacts the lower claw resistance plate at a certain point, the potential of the positive resistance plate gradually accumulates charge through the contact point and falls to the potential of the contact point. go. After waiting for a certain period of time (hereinafter referred to as TO) (step 14), the converted value of the analog/digital converter is read and stored in variable W1 (step 15). Next, turn on 01/Q2, Q3/Q4
is turned off to accumulate charge on the upper and lower resistor plates, and the potential is set to a high level voltage (step 6). Steps 12 to 14) repeat the steps 7 to 9 as they are, and store the read conversion value of the analog/digital converter in variable W2 (step 15).

Compare the difference between the stored values of Wl and W2 with the threshold value (Step 16) or more, it is assumed that the contact resistance between the upper and lower resistance plates is high and unstable, and an error value is stored in the variable X (Step 19). , if it is smaller than the L threshold, then the variable
From l and W2, a value calculated by equation (3) to be described later is stored, and a value calculated by equation (4) is stored in variable R (step 18). The X coordinate reading is performed by the above procedure.

The fourth section is flowchart 1 of the Y coordinate reading procedure, but in Fig. 3, X is read as Y, R, as RY, and Q
1 and 02, Q3 and 04, and SWI and SW2 were completely replaced.

FIG. 5 shows an example of the change in the potential of the positive resistance plate during the X-coordinate reading procedure of FIG. 3 by a curve 37 in the figure. Point 26 in the figure is step 6, step 2 in the figure
The time point 7 is step 7, and the time point 28 in the figure is step 10.
, the time point 29 in the figure is step 11. The time point 30 in the figure corresponds to step 12, and the time point 31 in the figure corresponds to step 15. In addition, 25 in the figure is the value of Wl in which the converted value of the analog/digital converter is stored, 23 in the figure is the value of W2 in which the converted value of the analog/digital converter is stored, and 24 in the figure is Wl
, , indicates the value of X calculated from W2 according to equation (3) described later.

FIG. 6 shows an example of the relationship between the input load that applies stress to the loss resistance plate and the contact resistance of the upper and lower resistance plates by a curve 38 in the figure. From the contact resistance value, the applied input weight can be calculated according to the above relationship.

FIG. 7 is a circuit diagram in which each component of the coordinate input means of the present invention is replaced with equivalent electric elements. In the figure, 32 indicates the equivalent resistance of the lower claw resistance plate with a high level voltage applied to the X raw electrode and a low level voltage to the - Equivalent resistance that represents the positive loss resistance plate that isolates the electrode from high and low level voltages, 36 in the figure is the input capacitance of the analog/digital converter, and an equivalent capacitor that equivalently represents the sum of the capacitance between the upper and lower resistance plates. The symbol 36 in the middle is a voltmeter symbol indicating a voltage observation point. As shown in FIG. 6, the contact resistance changes greatly depending on the input load. −
If the input weight is small but stable during the time when the coordinates are read twice, it is possible to estimate the true coordinate values with high accuracy by the following means.

If the true coordinate value is X, then W1 and W2 are W1=X-[1-exp(-To/C1R+R51)]
・ ・ ・ (1) W2=(vH−Xi・ex
p(-To?C(R+Rs))+X (2). Here, (8) is the value of the high level voltage, C is the capacitance of the equivalent capacitor, R is the contact resistance, and Rs is the resistance from the contact position on the resistive film to the electrode. (1), (2) above
) formula, X=WIVH/fVH+W1−W2+ −
-・(3). Since the above Rs is proportional to the contact position, using the resistance value ρ per unit distance of the resistive film, Rs=ρ
・X... can be written as (5). Therefore, the contact resistance R is 2-MI R=To・C11n V'-9・X
・ ・ ・ (4) vH becomes.

FIG. 8 shows a drawing input device to which the coordinate input device according to the present embodiment is applied. 40 in FIG. A graphic display means for checking the resistance value by displaying a circular shape having a diameter proportional to the reciprocal of the contact resistance value at the corresponding display position. It is a data transfer means for transferring data from the means. FIG. 9(a) is an example of drawing two points using the drawing input device with different pen pressures. 43 in the figure is a point input with weak pen pressure, and 44 in the figure is a point input with strong pen pressure. Figure 2 (b) also shows the kanji ``-
” is input.

[Effects of the Invention] As described above, by using the coordinate input means of the present invention, it is possible to realize a coordinate human-powered device that can measure the contact resistance that changes depending on pen pressure together with coordinate values in real time without increasing the cost at all. can.

In addition, since a special pen pressure detection mechanism is not required, if the coordinate input means is used in a system that represents the brushstrokes with pen pressure and stores them as digital data, such as in a drawing system, the user can easily You can input your drawings as digital data with a feeling similar to using a writing instrument.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the hardware of a coordinate input means according to an embodiment of the present invention. FIG. 2 is a flowchart showing an overview of the control procedure of the coordinate input means according to an embodiment of the present invention. FIG. 3 is a flowchart showing the procedure for reading the X coordinate value of the coordinate input means according to the embodiment of the present invention. FIG. 4 is a flowchart showing a procedure for reading the Y coordinate value of the coordinate input means according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of a change in the potential of the loss resistance plate in the X-coordinate reading procedure of FIG. 3. Figure 6 shows the input load that applies stress to the loss resistance plate,
The figure which shows an example of the relationship of the contact resistance of an upper and lower resistance plate. FIG. 7 is a circuit diagram in which each component of the coordinate input means according to an embodiment of the present invention is replaced with isometric electric elements. FIG. 8 is a diagram showing a drawing device to which the coordinate input means of an embodiment of the present invention is applied. FIG. 9 is a diagram showing an example of drawing using a drawing device to which the coordinate input means of one embodiment of the present invention is applied.・Positive loss resistance plate ・Lower nail resistance plate ・Y raw electrode ・Y-electrode ・X-electrode ・X raw electrode ・NPNI-ranjisku QI NPN l-ransistor Q2 PNP transistor Q3 1 O・ 11. 15 ・ 16 ・ 17, l 9 ・ 20 ・ 21 ・ ・ 22 ・ 23 ・ 24 ・ 25 ・ 27 ・ 28 ・ 29 ・ PNP transistor Q4 3.14 Transistor control output analog switch SWI Analog switch SW2 Analog switch control output analog /Interface between digital converter PCU and analog/digital converter Programmable controller unit (PCU) - Value of interface Wl between PCU and external equipment Average value of Wl and W2 Value of W2 Step 6 point step Step 7 point step 10 point step 11 time point 3 o ・ 31 ・ 32 ・ 35 ・ ・ 37 ・ ・ 38 ・ 40 ・ 41 ・ 42 ・ 43 ・ 44 ・ ・Step 12 point ・ Step 15 point ・ Equivalent resistance showing lower claw resistance plate Equivalent resistance showing contact resistance・Equivalent resistance that indicates the positive loss resistance plate ・Equivalent capacitor that shows the input capacitance of the analog/digital converter, the sum of the capacitance between the upper and lower resistance plates ・Voltmeter that indicates the observation point of the potential of the positive loss resistance plate In the procedure for reading the X coordinate・Curve showing the change in potential of the upper and lower resistance plates ・Curve showing the relationship between the input load that applies stress to the positive resistance plate and the contact resistance of the upper and lower resistance plates ・Coordinate input device ・Graphic display device ・Data transfer means ・Weak Points input with pen pressure/Points input with strong pen pressure Figure 2 Figure 5 Input load Figure 7 Figure 8

Claims (1)

[Claims] (1) a) Two resistive films facing each other and having two or more electrodes for monitoring the potential level by other circuits and applying two levels of high and low voltage; b) c) means for applying two types of voltages, low level and high level, to the electrode on the resistive film; c) the electrode;
d) analog/digital conversion means; and e) a high level voltage applied to one electrode with a resistive film on one side, and a high level voltage applied to the other electrode. When a low level voltage is applied to create a voltage gradient on the resistive film, the resistive film facing the resistive film is made to have a high impedance, and stress is applied to a certain point on the resistive film,
f) Before reading the coordinate values, in the coordinate input means that reads the electric potential of the part that is in contact due to deflection from the electrode of the resistive film made high impedance using the analog/digital conversion means, and converts the contact position into a numerical value based on the value. Then, apply only a high or low level voltage to both of the two resistive films, read the coordinate values immediately, and then apply another voltage other than the above level to both of the two resistive films. The coordinate input means is characterized in that the coordinate value is read immediately after, and the resistance value of the contact resistance of the touched portion is measured using the previously read value and the later read value.