JPH0480411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a technology related to a so-called digitizer used for inputting characters, figures, etc. by hand. The present invention relates to a coordinate input device for inputting the coordinate position of a contact point (hereinafter referred to as an "input point") by bringing the tip into contact with a coordinate input sheet.

<Prior art> As shown in FIG. 2, this type of conventional coordinate input device includes a coordinate input sheet 1A (hereinafter referred to as "X coordinate input sheet") for detecting the X coordinate position and a coordinate input sheet 1A for detecting the Y coordinate position. A coordinate input sheet (hereinafter referred to as "Y coordinate input sheet") 1B is stacked one above the other. Coordinate input sheets 1A and 1 respectively
In B, opposing electrodes 2 and 3 are arranged at both ends of an insulating sheet, and sheet resistances 4A and 4 are applied to the sheet surface between the two electrodes.
B, each coordinate input sheet 1A, 1
In B, the position of the opposing electrodes 2 and 3 is relative to the mating sheet.
It is positioned so that it is shifted by 90 degrees.

When you touch this coordinate input device with the tip of the stylus pen to input an input point, the switch
Close SW ₁ and SW ₂ and apply voltage to X coordinate input sheet 1A
By applying _E1 , the partial pressure at the input point P _A on this sheet is extracted from the partial pressure output end 6 of the Y coordinate input sheet 1B as X coordinate position information. Next, close switches SW ₃ and SW ₄ and press Y.
When voltage E ₁ is applied to the coordinate input sheet 1B, the partial pressure at the input point P _B on that sheet is extracted as Y coordinate position information from the partial pressure output terminal 7 of the X coordinate input sheet 1A. The X-coordinate position and Y-coordinate position of the input point can be determined by the information processing of the division.

By the way, in this type of coordinate input device, when the pen tip of the stylus pen comes into contact with the coordinate input sheets 1A, 1B and the internal switch of the stylus pen is turned on by pressure, the process of importing each position information of the X coordinate and Y coordinate is performed. It is starting to shift to

FIG. 3 shows a circuit configuration for detecting pen contact formed in a conventional device.
A is the surface resistance of the X coordinate input sheet 1A, 4B is the surface resistance of the Y coordinate input sheet 1B, and r is the contact resistance between the coordinate input sheets 1A and 1B when the pen is in contact. In the circuit of the same figure, each coordinate input sheet 1A, 1B
In the supply circuit for the voltage E ₁ there is a switch SW ₁
~SW ₄ is provided, and each partial voltage output terminal 6, 7
Switches SW ₅ and SW ₆ are connected between the A/D converter 5 and the A/D converter 5.
is in place.

In addition, a comparator 8 is connected to one of the partial voltage output terminals 6.
A resistor 9 is connected to one input terminal of the comparator 8 for applying a voltage _E2 higher than the voltage _E1 , and a comparison voltage is connected to the other input terminal of the comparator 8.
Resistor 1 to give E ₃ (E ₁ < E ₃ < E ₂ )
0 and 11 are connected, respectively. Note that the resistor 9 used has a resistance value sufficiently higher than the sheet resistances 4A and 4B (for example, 100KΩ to TMΩ).

In the above circuit, when waiting for input, the switch is
SW ₁ , SW ₂ , SW ₅ are "closed", switches SW ₃ , SW ₄ ,
SW ₆ is set to the "open" state, and voltage E ₁ is applied to the X coordinate input sheet 1A. When the tip of the stylus pen touches the coordinate input sheets 1A and 1B in this standby state, the voltage at the input point
Ex is Y coordinate input sheet 1B via contact resistance r
The voltage is taken out from the partial pressure output terminal 6 of . This voltage Ex
is input to the comparator 8, which inverts the comparison output to generate and output a pen contact signal, and then the A/D converter 5 converts the potential to
The size of Ex is read.

<Problems to be solved by the invention> However, in the above circuit configuration, the comparator 8
circuit components such as and resistors 9 to 10 are required,
Moreover, in addition to the power supply for supplying the voltage _E1 to each coordinate input sheet 1A, 1B, a separate power supply is required for supplying the voltage _E2 to the circuit section including the comparator 8, which increases the number of parts and increases the circuitry. There were problems such as increased complexity and increased costs.

The present invention is intended to solve the above-mentioned problems, and it is an object of the present invention to provide a simple and inexpensive coordinate input device that can easily detect pen contact without adding a separate power supply or a circuit including a comparator. With the goal.

<Means for Solving the Problems> The present invention includes an X coordinate input sheet for detecting the X coordinate position and a Y coordinate input sheet for detecting the Y coordinate position, and voltage is applied to each coordinate input sheet to detect pen contact. A coordinate input device for determining an X coordinate position and an X coordinate position by outputting a partial pressure at an input point according to , a second switch means having one end connected to the power supply and the other end connected to one end of the Y coordinate input sheet, and a pen contact detection means connected to the other end of the X coordinate input sheet or the Y coordinate input sheet. It is equipped with the following.

The pen contact detection means detects an X coordinate input sheet and a Y coordinate input sheet in a standby state before inputting position coordinates in which the power supply voltage is applied to one of the coordinate input sheets via the first switch means or the second switch means.
When the coordinate input sheet and the coordinate input sheet come into contact with each other due to pen contact, the pen contact is detected by detecting the contact resistance and the power supply voltage applied through the other coordinate input sheet to which the power supply voltage is not applied. There is.

<Operation> In a standby state in which either switch means is closed, the Y-coordinate input sheet and the Y-coordinate input sheet are not in contact with each other, and no power supply voltage is applied to the pen contact detection means.

When the X coordinate input sheet and the Y coordinate input sheet come into contact with each other due to pen contact, a power supply voltage is applied to the pen contact detection means via the contact resistance and the coordinate input sheet to which no power supply voltage is applied. The pen contact means detects pen contact by detecting this power supply voltage.

<Embodiment> FIG. 1 shows an equivalent circuit of a coordinate input device according to an embodiment of the present invention.

This coordinate input device is constructed by stacking two coordinate input sheets 1A and 1B vertically, like the one shown in _FIG . Voltage through ₂
E ₁ is also the sheet resistance 4B of Y coordinate input sheet 1B
A voltage E ₁ is applied to each of them via switches SW ₃ and SW ₄ . Each coordinate input sheet 1A, 1B
Switches SW ₅ and SW ₆ are connected to the partial voltage output terminals 6 and 7, and the pen contact detection circuit 13 is connected to the other terminal of the connection.
A detection resistor 12 and an A/D converter 5, which constitute the same, are connected. The detection resistor 12 has a sufficiently high resistance compared to the sheet resistances 4A and 4B, and when the A/D converter 5 reads the voltage across the detection resistor 12,
It detects pen contact.

Therefore, when waiting for input, switches SW ₁ and SW ₅ are "closed" and switches SW ₂ , SW ₃ , SW ₄ , and SW ₆ are "open".
Under this state, the voltage across the detection resistor 12 of the pen contact detection circuit 13 is zero.

Now, when the tip of the stylus pen contacts the coordinate input sheets 1A, 1B, the voltage _E1 is applied to the pen contact detection circuit 13 via the contact resistance r and the surface resistance 4B of the Y coordinate input sheet 4B, regardless of the contact coordinate position. This will be applied to the detection resistor 12.
As a result, a voltage _E1 appears at both ends of the detection resistor 12, and by reading this with the A/D converter 5, pen contact is detected.

When pen contact is detected, the switch is activated next.
SW ₁ , SW ₂ , SW ₅ are "closed", switches SW ₃ , SW ₄ ,
SW ₆ is set to the "open" state. This results in
A voltage _E1 is applied to the coordinate input sheet 1A, and the partial pressure at the input point P _A on the sheet is taken out from the partial pressure output end 6 of the Y coordinate input sheet 1B as X coordinate position information. Next, switch SW ₃ , SW ₄ ,
SW ₆ is "closed" and switches SW ₁ , SW ₂ , SW ₅ are "open"
As a result, the voltage _E1 is applied to the Y coordinate input sheet 1B, and the partial pressure at the input point P _B on that sheet is extracted from the partial pressure output end 7 of the X coordinate input sheet 1A as Y coordinate position information. It will be done. Through such time-sharing information processing, X-coordinate position information and Y-coordinate position information of the input point are obtained, and the A/D converter 5 determines the X-coordinate position and Y-coordinate position from this input information.

Note that the partial pressure at the input point is 0 depending on the position of the input point.
Since the voltage changes in the range of ~ _E1 , by connecting the reference terminal voltage of the A/D converter 5 to _E1 and the analog ground terminal to ground, the required measurement range can be obtained with full resolution.

<Effects of the Invention> As described above, in the present invention, X Coordinate input sheet and Y
When the coordinate input sheet and the coordinate input sheet come into contact with each other due to pen contact, the pen contact is detected by detecting the contact resistance and the power supply voltage applied through the other coordinate input sheet to which no power supply voltage is applied. This eliminates the need to use a special stylus or add a separate power supply, comparator, etc. to detect pen contact, simplifying the circuit and reducing costs by reducing the number of parts. The invention has remarkable effects such as being able to achieve the purpose of the invention.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing an equivalent circuit of a coordinate input device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the configuration of a conventional coordinate input device, and FIG. 3 is an equivalent circuit diagram of a conventional example. FIG. 1A, 1B... Coordinate input sheet, 13... Pen contact detection circuit, SW ₁ to _{SW 6} ... Switch.

Claims (1)

[Claims] 1. An X-coordinate input sheet for detecting the X-coordinate position and a Y-coordinate input sheet for detecting the Y-coordinate position, and a voltage is applied to each coordinate input sheet to calculate the partial pressure at the input point due to pen contact. A coordinate input device for outputting an X-coordinate position and a Y-coordinate position, the first switch means having one end connected to a power source and the other end connected to one end of the X coordinate input sheet, and one end connected to the power source. a second switch means whose other end is connected to one end of the Y coordinate input sheet; and a pen contact detection means connected to the other end of the X coordinate input sheet or the Y coordinate input sheet; The means is configured to input the X-coordinate input sheet and the Y-coordinate input sheet in a standby state before position coordinate input, in which the power supply voltage is applied to one of the coordinate input sheets via the first switch means or the second switch means. A coordinate input device configured to detect a pen contact by detecting the contact resistance and the power supply voltage applied through the other coordinate input sheet to which the power supply voltage is not applied when the coordinate input sheets come into contact with each other due to a pen contact. 2. The coordinate input device according to claim 1, wherein each of the coordinate input sheets has a sheet resistance formed on a sheet surface between opposing electrodes.