JPH05298013A - Pressure-sensitive coordinate input device - Google Patents

Abstract

PURPOSE:To provide the coordinate input device which has high durability and does not require any special parts by providing an operation processing means to calculate a pressed position on a coordinate instructing plate based on pressure detected by a pressure-sensitive means. CONSTITUTION:When one point on a transparent plate 12 is pressed by a pen, the force is distributed to four fixed points 14a-14d. The peripheries of the fixed points 14a-14d are bent corresponding to the force pressed to the respective points, and the outputs of distortion gauges 16a-16d are changed corresponding to the bending. The outputs of the distortion gauges 16a-16d are amplified by distortion interfaces 18a-18d and A/D converted. The result is dispatched to an operation processor 20 as a distortion output. The operation processor 20 calculates the coordinates instructed on the transparent plate 12. Further, the operation processor 20 drives a display controller 22, and a display position on the screen of a display device 10 corresponding to the coordinate position instructed on the transparent plate 12 is painted in black. Thus, a curve drawn on the transparent plate 12 can be displayed on the screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive coordinate input device.

[0002]

2. Description of the Related Art Generally, as an input / output device for information equipment,
A coordinate input display device in which a coordinate detection device and a display device are integrated is often used. In the coordinate input display device, predetermined data is input by visually recognizing a screen displayed on the display device and pressing the coordinate detection surface corresponding to the display content with a pen or a finger.

There are several types of coordinate input devices used in this type of coordinate input display device. As a typical one of them, there is a resistance film type (pressure sensitive type). This resistance film method will be described with reference to FIGS. FIG. 5 is a cross-sectional structure of the coordinate pointing surface of the coordinate input device, and FIG. 6 is a diagram for explaining the operation principle.

In the coordinate input device, as shown in FIG. 5, a spacer 1 is sandwiched by uniform resistance films 2 and 3 from the upper side and the lower side, and a polyester film 4 is laminated on the upper resistance film 2 to form a lower resistance film. The film 3 is formed by laminating the glass 5 on the film 3. The upper and lower resistance films 2 and 3 are normally in a non-conductive state, and are brought into a conductive state when the coordinate detection surface is pressed by a finger, a pen or the like and comes into contact with the coordinate detection surface.

As shown in FIG. 6, the resistance films 2 and 3 are
Constant current source 6, resistors 7a to 7d, and operational amplifiers 8a to 8
Connect d. In the non-conduction state, no current flows even if a constant current is supplied to the resistance films 2 and 3, so that the operational amplifiers 8a to 8a
No voltage appears in the output voltages Vx1, Vx2, Vy1, Vy2 of d. When the resistance film 2 is pushed through the polyester film 4 with a certain weight, the upper and lower counter films 2 and 3 are brought into a conductive state at one point, and a constant current flows as shown in FIG.

This constant current is applied to the upper and lower resistance films 2, 2.
Divide in proportion to the position pressed in 3. Therefore, the voltages Vx1, Vx2, Vy1, and Vy2 appear in proportion to the pressed position. Coordinates Lx and Ly at this time are obtained from the following equations (1) and (2), respectively. Lx = Vx1 / (Vx1 + Vy2) ... (1) Ly = Vy1 / (Vy1 + Vy2) ... (2)

[0007]

As described above, the conventional coordinate input device using the resistance film system has the following problems.

That is, as shown in FIG. 5, when the counter membrane 2 is pushed through the polyester film 4, the counter membranes 2 and 3 are electrically connected to each other, so that the polyester film having low strength is apt to deteriorate and is durable. Was bad.
In addition, since it is necessary to obtain the coordinate position from the state of conduction at one point, the resistance films 2 and 3 which are special parts are required. The present invention has been made in view of the above points, and an object thereof is to provide a coordinate input device that has high durability and does not require special parts.

[0009]

According to the present invention, a coordinate pointing plate supported by a plurality of fixed points and a pressure applied to each fixed point by pressing an arbitrary position on the coordinate pointing plate are detected. The pressure sensing means and the arithmetic processing means for obtaining the position pressed on the coordinate indicating plate based on the pressure detected by the pressure sensing means.

[0010]

With this structure, the coordinate indicating plate (transparent plate 12) can be made of a hard material, so that the coordinate indicating device can be made of a polyester film as compared with the conventional coordinate input device. The durability can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the coordinate input device according to the embodiment. In this embodiment, the coordinate input device and the display device are integrated to form a coordinate input display device. In FIG. 1, the display device 10 displays an image such as characters on a screen under the control of a display control device 22 described later. The transparent plate 12 serves as a coordinate designating surface for designating a coordinate position with a pen, a finger, or the like. The content displayed on the screen of the display device 10 can be visually confirmed through the transparent plate 12.

The transparent plate 12 has fixed points 14a, 14b, 1
It is fixed on the display device 10 at 4c and 14d. The strain gauges 16a, 16b, 16c, and 16d are adhered to the fixed points 14a to 14d of the transparent plate 12, respectively, so that the pressure applied to the fixed points 14a to 14d when the coordinate designating surface of the transparent plate 12 is pressed. To detect. The strain gauge interfaces 18a, 18b, 18c, 18d correspond to the strain gauges 16a, 16b, 16c, 16 respectively.
A / A is amplified by amplifying the minute change in the output current output from d.
It is D-converted and output to the arithmetic processing unit 20 as a distortion output.

The arithmetic processing unit 20 calculates and finds which coordinate position is pressed on the coordinate designating surface of the transparent plate 12 based on the strain output from each strain gauge interface 18-18d. The display control device 22 controls the image display of the display device 10 according to the processing content of the arithmetic processing device 20.

Before explaining the specific operation, the principle of coordinate detection in the coordinate input device of the present invention will be described. In the present invention, the transparent plate 12 is provided on the upper surface of the display device 10, and the pressure applied to each support portion (fixed points 14a to 14d) is detected by the user pressing the transparent plate 12, and the pressed position is determined. It is what you want.

As shown in FIG. 2, the case where the fixing points 14a to 14d are provided at the four corners of the transparent plate 12 will be described as an example. As shown in FIG. 2, the X direction and the Y direction are orthogonal to each other.
Take the Y coordinate system. Arbitrary coordinates (x,
It is assumed that y) is pressed by the user with a force f.

Each fixed point 14a-14 when pressed
If the force on d (subtracting the force due to the weight of the transparent plate 12 or the like) is F1, F2, F3, F4, the transparent plate 1
The following equations (3), (4), and (5) are established from the relationship between the force applied to 2 and the Mamenato around the coordinate axis.

F = F1 + F2 + F3 + F4 (3) fx + (F1 + F3) X0- (F2 + F4) X0 = 0 (4) fy + (F3 + F4) Y0- (F1 + F2) Y0 = 0 (5)

When x and y are obtained from the equations (3) to (5), x = (-F1 + F2-F3 + F4) X0 / (F1 + F2 + F3 + F4) ... (6) y = (F1 + F2-F3-F4) Y0 / (F1 + F2 + F3 + F4) ) ... (7) and the coordinates (x,
y) is detected.

Next, regarding the specific operation of the embodiment,
This will be described with reference to the flowcharts shown in FIGS. 3 and 4. Here, as an operation example, a curved line written by using, for example, a pen on the transparent plate 12 is directly displayed on the display device 10.
The case of displaying on the screen will be described.

First, when one point on the transparent plate 12 is pressed by the pen, the force is distributed to the four fixed points 14a to 14d according to the expressions (3), (4) and (5). The periphery of the fixed points 14a to 14d bends according to the force applied to each, and the outputs of the strain gauges 16a to 16d change according to the bending. The outputs of the strain gauges 16a to 16d are amplified and A / D converted by the strain cage interfaces 18a to 18d. The result is passed to the arithmetic processing unit 20 as a distortion output.

The arithmetic processing unit 20 fills the display screen of the display unit 22 white (dot off) as an initial setting via the display control unit 22 (step S1). Next, FIG.
The coordinates of the point pressed on the coordinate designating surface of the transparent plate 12 are calculated and obtained according to the flow chart shown in (step S2).

First, the arithmetic processing unit 20 extracts F1 and F from four distortion outputs based on the relations of the equations (3), (4) and (5).
2, F3 and F4 are calculated (step A1). These are values obtained by subtracting the force due to the weight of the transparent plate 12.
Next, the total sum of F1, F2, F3 and F4 is calculated and obtained,
It is determined whether or not this total exceeds a certain threshold value (step A2).

If the total sum exceeds the threshold value, it is determined that the coordinate position is instructed (writing of characters, etc.) at any position on the transparent plate 12. Here, the depression flag indicating that the position is designated on the transparent plate 12 is turned on (step A3). Then, the coordinates (X, Y) of the point pressed on the transparent plate 12 are obtained from F1, F2, F3, and F4 obtained in step A1 according to equations (6) and (7) (step A4). In step A2, F
If the sum of 1, F2, F3, and F4 does not exceed the threshold value, it is considered that the position is not designated, the depression flag is turned off (step A5), and the coordinate calculation process is ended.

After the coordinates (X, Y) are obtained in step S2 (after the coordinate calculation is performed), the depression flag is checked (step S3). Here, if the press flag is on,
The arithmetic processing unit 20 drives the display control unit 22 to paint the display position on the screen of the display unit 10 corresponding to the coordinate position (x, y) designated on the transparent plate 12 black (dot-on) (step on). S4). If the push flag is off, the process of step S4 is skipped (step S
3).

Next, it is determined whether or not the coordinate input processing is to be ended. In this embodiment, the determination method is not particularly limited. If the process is not ended, the coordinate input process described above is repeated.

In accordance with the above procedure, the display position corresponding to the point pressed with a pen or the like on the transparent plate 12 is painted black, so that the curve written on the transparent plate 12 is displayed on the screen as it is. Can be made

In this way, since the supported coordinate position is detected from the pressure applied to the fixing points 14a to 14d that support the transparent plate 12, the material of the transparent plate 12 can be freely selected. Therefore, the strength of the coordinate pointing surface can be increased and the durability is improved. Further, it is possible to configure without the need for a special resistance film. In the above embodiment, the transparent plate 12 is fixed to the four fixing points 14a.
It is supposed that the support is carried out by ˜14d, but the number thereof is not particularly limited.

In the above embodiment, the strain gauge 1
Although the pressures at the fixed points 14a to 14d are detected using 6a to 16d, other pressure detection means may be used.

[0029]

As described above, according to the present invention, the coordinate pointing surface is detected by detecting the position pressed on the coordinate pointing surface based on the pressure applied to the fixed point supporting the coordinate pointing surface. Since the constituent materials can be arbitrarily selected, the durability can be improved and special parts such as a resistance film can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a coordinate input device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of coordinate detection.

FIG. 3 is a flowchart illustrating an operation of the arithmetic processing unit 20 for displaying a designated position.

FIG. 4 is a flowchart for explaining a coordinate calculation process.

FIG. 5 is a diagram showing a sectional structure of a coordinate designating surface of the coordinate input device.

FIG. 6 is a diagram for explaining the operation principle of a coordinate input device using a conventional resistive film method.

[Explanation of symbols]

10 ... Display device, 12 ... Transparent plate (coordinate pointing plate), 14a
-14d ... Fixed point, 16 ... Strain gauge (pressure sensitive means), 18
... strain gauge interface, 20 ... arithmetic processing device (arithmetic processing means), 22 ... display control device.

Claims (1)

[Claims] 1. A coordinate pointing plate supported by a plurality of fixed points, pressure-sensitive means for detecting a pressure applied to each fixed point by pressing an arbitrary position on the coordinate pointing plate, and the pressure-sensitive means. A pressure-sensitive coordinate input device, comprising: an arithmetic processing unit that obtains a position pressed on the coordinate indicating plate based on the pressure detected by the unit.