JPS6029965B2 - Graphic input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphic input device that detects the position and size of an input point of an input graphic or the like.

Conventionally, graphic input devices detect only the position coordinates of input points, and cannot detect the size, shape, etc. of a writing tip such as a stylus used for input.

Therefore, it is not possible to determine whether the tip of the writing tip used for input is thick or thin, and when an input figure is displayed, it can only be displayed as a figure with no line width. Also,
In systems such as remote blackboard systems or electronic blackboard systems that input and display handwritten characters and figures, the characters and figures are intentionally written thickly or thinly on the blackboard, but with conventional graphic input devices, this is not possible. However, since line width cannot be detected, it lacks naturalness.
This invention was made to solve the above-mentioned drawbacks, and is designed to detect the position coordinates and size of an input point.

Hereinafter, the present invention will be explained in detail based on the drawings. 1st
The figure is a configuration diagram showing an embodiment of the present invention, in which 1 is an input pad, 2 is a protective sheet, 3 and 4 are first and second electrode sheets, 5 is a pressure-sensitive conductive rubber sheet, and 1 is a river detection circuit. It is.

As shown in FIG. 1, the input pad 1 is composed of a flexible protective sheet 2, first and second electrode sheets 3 and 4, and a pressure-sensitive conductive rubber sheet 5. First electrode sheet 3 for detecting coordinates in the y direction
A pressure-sensitive conductive rubber sheet 5 is disposed on the lower surface thereof, and has a property that when pressure is applied, conductivity occurs only in the vicinity of the point where the pressure is applied.

A second electrode sheet 4 for detecting coordinates in the x direction is arranged on the lower surface of the pressure sensitive conductive rubber sheet 5. Second
The arrangement of the electrode sheet 4 is to turn the first electrode sheet 3 over'.
Then, when rotated further by 90 degrees, the same surfaces of the first and second electrode sheets 3 and 4 face each other with the pressure-sensitive conductive sheet 5 in between. First and second electrode sheets 3, 4
is constructed as shown in detail in FIG.

In FIG. 2, 31 is a uniform resistor with uniform electrical resistance;
32 is an electrode provided at both ends of the uniform resistor 31, 33 is a sheet substrate, and 34 is a wire electrode. Line electrodes 34 are formed in parallel at regular intervals on a sheet substrate 33 which is a flexible insulator, and one end of the line electrodes 34 is connected to a uniform resistor 31. Since the input pad 1 is configured as described above, its electrical equivalent circuit can be written as shown in FIG. First electrode sheet 3
A of the electrodes 32 at both ends of the uniform resistor 31 attached to
-B is divided into minute resistances ry,,ry2,...ryn, and a uniform resistor 31 attached to the second electrode sheet 4
Similarly, between C and D of the electrodes 32 at both ends of rx,, rx2,
..., divided into r skins. Further, the line electrodes 34 of the first and second electrode sheets 3 and 4 can be expressed as a lattice of y, y2, . . . , yn. When there is an input on the input pad, that is, when one point on the protective sheet 2 of the input pad 1 is pressed with a pen or the like, the broken line 4 in FIG.
0 portion is pressed, and the rubber at the broken line 40 portion of the pressure-sensitive conductive rubber sheet 5 becomes electrically conductive.

Therefore, the lattice points (4 points in FIG. 4) inside the broken line 40 in FIG. 4 come into contact. In order to explain the operating principle of this invention, the individual resistors in FIG. 4 are simplified as continuous resistors as shown in FIG.

Even with this simplification, the principle is the same if digital changes are ignored. Therefore, the following explanation will be made using the model shown in FIG. 5. The position of the left side of the pressed part is x, the width in the y direction is △x, the position of the upper end is y,
Let the width in the y direction be Δy.

In addition, the length of the resistance in the x direction and the y direction is Lx
, Ly, and the resistance per unit length is p. Such an input pad 1 is connected to a detection circuit shown in FIG. In FIG. 6, 60 is a constant current source, 61 is a V terminal, and 62 is a constant current source.
is the V2 terminal, and 63 is the Z terminal. Next, the operation will be explained.

In FIG. 6, in order to obtain x and y, switches S, ,
The contacts of S2 and S3 are respectively S, → a, S2 → a, S3
1a. Current 1 from constant current source 60 forms a loop through A→P→C. Since the differential amplifiers A, A2 have high input impedance, V and terminal 61 have 1, y, and
A voltage of 1.x.p appears at the V2 terminal 62. For simplicity, the gain of the differential amplifiers A, . . . is assumed to be 1. Since the power supply 1 and the resistance p are constant, V,
Voltages proportional to the y-coordinate and the x-coordinate are obtained at the terminal 61 and the V2 terminal 62, respectively. Regarding the presence or absence of input, if it is pressed, a loop is formed as described above and a voltage is generated across the resistor Rz, so a voltage is generated at the Z terminal 63 of the output of the amplifier. Further, if it is not pressed, the pressure-sensitive conductive rubber sheet 5 will not conduct, and no loop will be formed, so no voltage will appear at the Z terminal 63. Therefore, the presence or absence of input can be determined by the presence or absence of voltage at the Z terminal 63. Next, in order to find the width Δy in the y direction, switch S. ,S2,
The contacts of S3 are set to S, →a, S2→b, and S3→b, respectively.

The current 1 from the constant current source 60 passes through the contact a of the switch S and changes from A to B, forming a loop. Therefore, V,
Since a voltage of 1.(Ly-Ay).p appears at the terminal 61, since Ly is constant, a voltage proportional to the width Δy of the input point in the y direction is obtained. Next, in order to find the width △× in the x direction, the contacts of switches S, , S2, and S3 are changed to
b, S2→a, S3→a, the current 1 from the constant current source 60 passes through the contact b of the switch S, passes through D→C, and forms a loop.

Therefore, the V2 terminal 62 has 1・(Lx−△x)・
Since the voltage p appears, the length Lx of the resistance in the x direction is constant, so a voltage proportional to the width Δx of the input point in the x direction is obtained. If there is pressure as described above, switch S
, S2, S3 as appropriate, the position of the input point, the coordinate statement, y, and the width Δx, Δy can be obtained at the V terminal 61 and the V2 terminal 62.

In the above description, the case where the pressure-sensitive conductive rubber sheet 5 is included as a component of the input pad 1 has been described, but if the pressure-sensitive conductive rubber sheet 5 is not used and the pressure-sensitive conductive rubber sheet 5 is provided between the first electrode sheet 3 and the second electrode sheet 4. By providing a suitable spacer or increasing the gap, the two electrode sheets 3 and 4 are pressed together.
It is also possible to have a structure in which the two are in contact with each other.

As explained above, this invention has the advantage that since the position and size of the pressed part can be detected, the line width of the input line figure can also be displayed by connecting to a display device via a communication line. There is.

In addition, since the size of an object placed on the input pad can be detected, for example, in a remote blackboard system, by detecting the position and size of the blackboard eraser, it is possible to determine the area of the blackboard surface erased by the blackboard eraser. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the construction of an embodiment of the present invention, FIG. 2 is a detailed perspective view of the electrode sheet shown in FIG. 1, FIG. 3 is an equivalent circuit diagram of the input pad shown in FIG. 1, and FIG. FIG. 5 is an equivalent circuit diagram of the input pad when there is an input, FIG. 5 is a diagram showing how to take the coordinates of the input pad, and FIG. 6 is a block diagram of the detection circuit. In the figure, 1 is an input pad, 2 is a protective sheet, 3 is a first electrode sheet, 4 is a second electrode sheet, 5 is a pressure-sensitive conductive rubber sheet, 10 is a detection circuit, 31 is a uniform resistor, 32 is an electrode, 33 is a sheet substrate, 34 is a wire electrode, 6 constant current sources,
61 is a V terminal, 62 is a V2 terminal, and 63 is a Z terminal. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. It has an input surface for applying pressure and input, and a plurality of long thin wire electrodes arranged in parallel and insulated from each other in the range including the area overlapping with this input surface, and one end of these wire electrodes has a uniform electric field. a first electrode sheet connected to a resistor having a uniform resistance; and a first electrode sheet having the same configuration as the first electrode sheet, the wires of the first electrode sheet being on the lower surface of the first electrode sheet. a second electrode sheet in which line electrodes are arranged perpendicular to the direction of the electrodes; a means for supplying a constant current; and a voltage generated across the uniform resistors of the first and second electrode sheets. A graphic input device comprising means for detecting the constant current, means for supplying the constant current, and means for switching the loop of the current flowing to the uniform resistor of the first and second electrode sheets.