JPS6235937A - Pen input detecting circuit for coordinate input device - Google Patents

Abstract

PURPOSE:To connect a make contact type switch and a break contact type switch to the same detecting circuit by providing one detecting circuit which outputs the presence of pen input with the rise of a pulse and outputs the absence of pen input with the fall of the pulse. CONSTITUTION:Switch circuits 6 and 7 are incorporated in a pen provided with a make contact type switch SW1 and a pen provided with a make contact type switch SW2 respectively. A voltage comparator 5 of an input detecting circuit 3 compares voltages Va and Vb, and the pulse is allowed to rise if the voltage Va is higher, and the pulse is allowed to fall if the voltage Vb is higher. Thus, the rise of the pulse of the output of the detecting circuit 3 indicates the presence of pen input and the fall of that indicated the absence of pen input when either pen is used.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pen input detection circuit for a coordinate input device.

[Conventional technology]

A coordinate input device that detects the coordinates of an input point on an input surface of a tape or tablet with an input pen is usually provided with an input detection circuit for detecting the presence or absence of pen input. Conventionally, an input pen has a make-contact type switch that is turned on by the pressure of the pen during input, and the input detection circuit
It detects whether this switch is on or off and generates an electrical signal indicating the presence or absence of pen input.

[Problem that the invention seeks to solve]

As mentioned above, the conventional pen input detection circuit for coordinate input devices detects the on/off state of the make contact type switch inside the pen, and when it is on, it indicates that there is an input, and when it is off, it indicates that there is no input. Generates and sends a signal to the terminal indicating the However, pens equipped with a make-contact type switch require a considerable amount of pen pressure to turn the switch on when inputting, so when inputting points, the switch does not provide a clear click feeling when inputting. It is suitable when it is more convenient to draw with a light pen pressure, such as when inputting patterns such as letters and figures, but it is not suitable when it is more convenient to draw with light pen pressure.

In the latter case, a pen equipped with a break contact type switch that can be turned off even with light pressure is suitable. In order to be able to deal with both of the above cases, one pen is equipped with a make contact type switch and the other is equipped with a break contact type switch, so that input can be performed with either pen depending on the input purpose. There is a must-have hair. However, in these two types of pens, the on/off states of the switches are opposite to each other, so two types of input detection circuits are provided.
In addition, when inputting data, it is necessary to connect the pen switch and the input detection circuit depending on the type of pen used, which increases the size of one circuit and makes the connection operation difficult during use. Identify problems.

An object of the present invention is to solve the above-mentioned problems, and to provide a coordinate system that allows both a pen equipped with a make contact type switch and a pen equipped with a break contact type switch to be connected to the same pair of terminals, without increasing the size of the circuit. An object of the present invention is to provide a pen input detection circuit for an input device.

[Means for solving problems]

The circuit of the first aspect of the present invention is provided in pairs with a first terminal connected to one end of the switch, which is in an off state when no input is being made and is in an on state according to pen pressure during input. A first switch circuit having a second terminal and provided in the first input vent, and connected to one end of a switch that is in an on state when no input is being made and becomes an off state arm depending on the pen pressure during input. at least one of a second switch circuit provided in the second input pen and having a second terminal provided in a pair therewith and a first terminal provided in a pair therewith; the first and second input terminals for connecting the first and second terminals of any one of the switch circuits, respectively, and a predetermined DC voltage and a first voltage between the first input terminal and a voltage divider circuit that generates a piezoelectric voltage and a second divided voltage between the DC voltage and the second input terminal; and an electric circuit that compares the magnitudes of the first and second divided voltages and shows the result. and an input detection circuit having a voltage comparator for generating and transmitting a signal.

The circuit of the second invention includes a first terminal connected to one end of a switch that is turned off when no input is input and turned on according to pen pressure during input, and a second terminal provided in a pair therewith. a first switch circuit provided in the first input pen, and a first terminal connected to one end of a switch that is in an on state when no input is performed and is turned off in response to pen pressure during input. and a second terminal provided in pair therewith, at least one of the second switch circuits provided in the second input pen, and any of the first and second switch circuits. first and second input terminals for connecting the first and second terminals of one of the terminals, respectively, and a predetermined DC voltage and a first divided voltage between the first input terminal and the DC voltage. a voltage divider circuit that generates a second divided voltage; a voltage comparator that compares the magnitudes of the first and second divided voltages and generates and sends an electrical signal indicating the result; and a resistor. inversion necessity selection means for selecting and executing whether or not to invert the comparison result indicated by the output signal of the voltage comparator in response to the level of the voltage level of the second terminal to which a DC voltage is applied through the voltage comparator; and an input detection circuit.

〔Example〕

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

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The switch circuits 6 and 7 are built into a pen provided with a make contact type switch SW1 and a pen provided with a break contact type switch SWt, respectively. Connection terminals 11 and 12 of the switch circuit 6 are a switch SW1 and a resistor r, respectively.

Connect to ground via. It is also connected to ground via a switch circuit and an 8W switch. When using a pen with a built-in make-contact type switch SW during input, connect the terminals 11 and 12 to the input terminals of the input detection circuit 30 using connectors, respectively, as shown by the solid lines. Connect to 1 and 2. Also a break contact type switch SW! When using a pen with a built-in pen, terminals 21 and 22 are connected to terminals 1 and 2, respectively, as shown by broken lines. That is, no matter which pen you use, you only need to connect it to the same pair of terminals.

In the input detection circuit 3, a voltage V obtained by dividing the voltage between the DC voltage VD and the voltage at the terminal 1 using resistors R3 and R,
a, and voltage vb obtained by dividing voltage VD and the voltage at terminal 2 using resistors r and r, voltage comparator 5
It is guided by. The voltage comparator 5 compares the voltages Va and Vb, and generates and sends out a pulse signal in which, for example, the pulse falls when the former is higher, and the pulse rises when the latter is higher. The values of the resistances R1 to R3 and the resistances r, 1r2 and rj are determined by the following inequality: (1) (rm + rs) /rt >""/H
,, and ツ(bird+几s) /a.

)　rt/r.

Set it so that it satisfies. For example, 4°=rs
/, , and if R1 and ", are both non-zero, formula (1) is satisfied. Or b 'M""
On" Heron) R2,7'm,, and Rs>lls・r
, /r, If each resistance value is set so that Rt (>0) holds, formula (1) will be satisfied. In this case, it is sufficient to short-circuit the resistor r, and the resistor r is not required. It is.

When the switch circuit 6 is connected to the input detection circuit 3, the switch SW is in an off state when there is no input.

Obviously, va:>vb, and the switch SW is in the on state at the time of input, and the first equation of equation (1) is established, so vl, :) v,. Therefore, in this case, the pulse signal sent out by the voltage comparator 5 is low when there is no input, and is high when it is input.

When the switch circuit 7 is connected to the input detection circuit 3,
When there is no input, switch SW is in the on state, and formula (1)
Since the second equation holds true, v a ) v b, and the switch SW is in the OFF state at the time of input, clearly vb>v. Therefore, in this case as well, the output pulse signal of the voltage comparator 5 falls when there is no input, and rises when it is input.

That is, no matter which pen is used, one input detection circuit 3 can obtain a pulse signal in which the rising edge of the pulse indicates the presence of pen input, and the falling edge of the pulse indicates the absence of pen input. Note that capacitors CI and C1 in the input detection circuit 3 are connected to the switch circuit 6 or 7 and the input detection circuit 3.
This connection is made to attenuate external noise components caused by electrical fag conduction within the connection cord between the 2 is a circuit diagram showing a second embodiment of the present invention. The switch circuits 8 and 9 of this embodiment each have the resistance r of the switch circuit 6 of the first embodiment.

and a configuration in which the resistor R8 of the switch circuit 7 is eliminated. That is, the terminal 12 of the switch circuit 8 is connected to ground, and the switch circuit 8 is connected to ground.

The terminal 21 of the child circuit 9 is left open. Furthermore, the input detection circuit 4 of this embodiment has a configuration in which a resistor R1 is additionally connected between the terminal 1 and the ground compared to the input detection circuit 3 of the previous embodiment.

In this embodiment, the resistors R1 to It, and the resistor rl
The value of e 1m is given by the following inequality (2) (R19)/1(1>'Chushizo2).

Set it so that it holds true.

When the switch circuit 8 is connected, formula (2) is used when there is no input.
'v, ) vb holds from the inequality relation in front of
Also, when inputting, from the inequality relationship at the end of equation (2), vb)
v.

holds true. When the switch circuit 9 is connected, when there is no input, v, )vb will be obtained from the inequality at the front of equation (2), and when there is an input, Vb>Va will obviously hold.

In other words, no matter which pen is used, a pulse signal can be obtained from one input detection circuit 4, in which the rising edge of the pulse indicates the presence of pen input, and the falling edge of the pulse indicates the absence of pen input. In this embodiment, since it is not necessary to accommodate a resistor in both switch circuits 8 and 9, there is an advantage that the switch circuit can be downsized by -19-. Note that, contrary to the second embodiment, a configuration is used in which the terminal 12 is left open, the terminal 21 is grounded, and a resistor is additionally connected between the terminal 2 of the input detection circuit 3 and the ground. It is clear that input from either pen can be made detectable.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention. The switch circuit 8 has the same configuration as the second embodiment, but the switch circuit 10 has a configuration in which the terminal 21 is connected to the ground via a break contact type switch SW, and the terminal 22 is left open. .

In the input detection circuit 13, a voltage v1 is obtained by dividing the voltage VD and the voltage at the terminal 1 by the resistance ratio and R2, and a voltage Wb is obtained by dividing the voltage VD by the resistors r and rl.
is led to the voltage comparator 5. Also, a resistor R is connected to terminal 2.
, a voltage VD is applied through the terminals . The output signal of voltage comparator 5 and the voltage signal of terminal 2 are exclusive ORed (EX
-OR) is led to gate 14. In this embodiment, the connection is made such that the output pulse of the voltage comparator 5 rises (or falls) when Va>Wb (or vb:>v). Also, the values of the resistances R, , R, and the resistances r, and r are determined by the following inequality: (31''/ > /R).

Set it so that it satisfies. When the switch circuit 8 (or 10) is connected to the input detection circuit 13, the output pulse of the EX-OR gate 14 rises when there is no input, and the output pulse of the EX-OR gate falls when there is an input. That is, no matter which pen is used, one detection circuit 13 can obtain a pulse signal in which, for example, the rising edge of the pulse indicates that there is a pen input, and the falling edge of the pulse indicates that there is no pen input.

〔Effect of the invention〕

As is clear from the above description, the present invention allows both pens equipped with a make contact type switch and pens equipped with a break contact type switch to be connected to the same pair of terminals without increasing the size of the circuit. This has the effect of realizing a pen input detection circuit for a coordinate input device.

[Brief explanation of the drawing]

1 to 3 are circuit diagrams showing embodiments of the present invention. 1.2, 11, 12, 21.22...Terminal, 3
, 4゜13... Input detection circuit, 5...
Voltage comparator, 6 to 10...Switch circuit, 14
...Exclusive OR (EX-OR), s
wl, sw, ・・・-・・su(,chi,R,-R□r
,~r,...group/resistance. Switch concave

Claims (10)

[Claims] (1) A first terminal having a first terminal connected to one end of a switch that is in an off state when no input is made and turns on in response to pen pressure during input, and a second terminal provided in a pair therewith. A first switch circuit provided in the input pen No. 1, and a second terminal connected to one end of the switch that is in an on state when no input is performed and an off state in response to pen pressure during input, and a second terminal is connected to this. at least one of the second switch circuits provided in the second input pen and having a first terminal provided therein; and the first switch circuit of any one of the first and second switch circuits. and a first divided voltage between a predetermined DC voltage and the first input terminal, and a first divided voltage between the DC voltage and the second input terminal for connecting the DC voltage and the second terminal, respectively. A voltage divider circuit that generates a second divided voltage between input terminals, and a voltage comparator that compares the magnitudes of the first and second divided voltages and generates and sends an electric signal indicating the result. 1. A pen input detection circuit for a coordinate input device, comprising: an input detection circuit having: (2) A pen input detection circuit for a coordinate input device according to claim (1), wherein a resistor is connected between the second terminal of the first switch circuit and the other end of the switch. (3) A pen input detection circuit for a coordinate input device according to claim (1), wherein a resistor is connected between the first terminal of the second switch circuit and the other end of the switch. (4) A pen input detection circuit for a coordinate input device according to claim (1), wherein the second terminal of the first switch circuit and the other end of the switch are short-circuited. (5) The pen input detection circuit for a coordinate input device according to claim (1), wherein the second terminal of the first switch circuit is in an open state. (6) A pen input detection circuit for a coordinate input device according to claim (1), wherein the first terminal of the second switch circuit and the other end of the switch are short-circuited. (7) The pen input detection circuit for a coordinate input device according to claim (1), wherein the first terminal of the second switch circuit is in an open state. (8) A first terminal having a first terminal connected to one end of a switch that is in an off state when no input is made and turns on in response to pen pressure during input, and a second terminal provided in a pair therewith. A first switch circuit provided in the input pen of No. 1, and a first terminal connected to one end of the switch that is in an on state when no input is performed and an off state in response to pen pressure during input, and a pair thereof. at least one of the second switch circuits provided in the second input pen and having a second terminal provided therein; and the first switch circuit of any one of the first and second switch circuits. and a first and second input terminal for connecting a second terminal, respectively, a predetermined DC voltage and a first divided voltage between the first input terminal and a second division of the DC voltage. A voltage dividing circuit that generates a piezoelectric voltage, a voltage comparator that compares the magnitudes of the first and second divided voltages and generates and sends out an electrical signal indicating the result, and a DC voltage that is applied via a resistor. an input detection circuit having an inversion necessity selection means for selecting and executing whether or not to invert the comparison result indicated by the output signal of the voltage comparator in response to the level of the voltage level of the second terminal. , a pen input detection circuit for a coordinate input device. (9) A short-circuit connection is made between the second terminal of the first switch circuit and the other end of the switch, and the second terminal of the second switch circuit is left open. The pen input detection circuit for a coordinate input device according to item (8). (10) short-circuiting the second terminal of the second switch circuit and the other end of the switch;
The pen input detection circuit for a coordinate input device according to claim (8), wherein the second terminal of the switch circuit is in an open state.