JPS5837783A - Coordinate input device using conductive incorporated resistive film - Google Patents

Abstract

PURPOSE:To constitute an equi-current circuit and to improve the accuracy of coordinate position detection, by placing a conductive film between two resistive sheets inserting a pressure sensing rubber between the conductor film and the resistive films respectively, providing a potential to the conductor film and pressing the film with a hand writing tool. CONSTITUTION:Coordinate information of a pressed position is detected through the pressing of a hand writing tool. A conductive film 19 is placed between two resistive films 17 and 21, a potential is given to this conductor film 19 and a hand writing tool 31 presses the film 19. Then, the position of the said pressed point is detected, by detecting a current flowing to the two resistive films 17 and 21 from the conductor film 19. Long straight-line conductors 24-30 and 34- 40 are mutually incorporated with a prescribed interval to each of the two resistive films 17 and 21 in parallel and pressure sensing rubbers 18 and 20 are provided between the said two resistive films 17 and 21 and the conductor film 19. By incorporating the plurality of the fine conductors 24-30 and 34-40 with the equi-interval to the resistive films 19 and 21, an ideal equi-current is formed circuit, allowing to improve the accuracy of coordinate position detection.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate input device that detects coordinate information of a pressurized position by pressurizing a writing instrument or the like.

2. Description of the Related Art A coordinate input device using an input board has conventionally been used as a device for detecting the coordinates of a pen position in a device 9 for inputting characters and figures into a computer or the like, such as a handwritten character input device.

FIG. 1 is a block diagram showing an example of a conventional coordinate input device, in which numeral 1 indicates a resistive film closely attached to an insulating plate.

2 is an AC power supply, and 8, 4, 5.6 are a group of diodes.

The anodes of the diode group 8 and the cathodes of the diode group 6 are commonly connected and connected to one side of the AC power source 2. Further, the cathodes of the diode group 4 located opposite to the diode group 8 and the anodes of the diode group 5 located opposite to the diode group 6 are also commonly connected and connected to the other side of the AC power source 2 and grounded. 7.8.
Terminal group 7 is connected to the cathode of diode group 8, terminal group 8 is connected to the anode of diode group 4, terminal group 9 is connected to the anode of diode group 4, and terminal group 9 is connected to the anode of diode group 4. Connected to the cathode of 5.

The terminal group lO is connected to the anode of the diode group 6. 11 is a pen, 12, 18 is a guiode, 14.
15 is a terminal. The tip of the pen 11 is connected to the cathode of a diode 12 and the anode of a diode 13 by conductive wires, the anode of the diode 12 is connected to a terminal 14, and the cathode of the diode 13 is connected to a terminal 15.

Therefore, when one point of the resistive film 1 is pressurized by the pen 11, when the AC power supply 2 is negative, the diode groups 8 and 4 are cut off, and the diode groups 5 and 6 are made conductive.

Therefore, a negative voltage at the pressure point is transmitted to the pen 11, and a negative voltage corresponding to the pressure point is outputted to the terminal 14 through the diode 12.

Conversely, when the AC power supply 2 is positive, the diode groups 5 and 6 are cut off, the diode groups 3 and 4 are conductive, and the positive voltage at the pressurizing point is transmitted to the pen 11, and the diode 1
A positive voltage corresponding to the pressurizing point is output to the terminal 15 through the terminal 8. Here, the terminal group 7゜8 is installed at opposite ends of the resistive film 1 in the Y direction, and the terminal groups 9 and 10 are installed at opposite ends of the resistive film l in the X direction, so that the terminals 14 are The negative voltage applied to the terminal 15 represents the Y-axis coordinate, and the positive voltage derived to the terminal 15 represents the Y-axis coordinate. In this way.

The coordinates of both the X and Y axes are detected, but in conventional coordinate input devices, the coordinates are detected through the input pen by electrical conduction caused by contact between the resistive film 1, which is the input panel, and the pen 11, which is the input pen. Ta.

Therefore, the input pen has the serious drawback that it requires a connection cord and has poor operability. Furthermore, in the case of the coordinate input device, it is not possible to place a form between the input panel and the input pen, and input data is input into the handwriting input device while taking notes. A method for detecting the coordinate position has also been proposed, but since it detects a minute signal, the peripheral circuits are expensive and it lacks practicality.

Furthermore, in the case of the coordinate input device, X,
Since opposing electrodes are formed in the Y2 direction, when a voltage is applied between one terminal group, current flows around between the terminal groups to which no voltage is applied.

This has the serious drawback that it is difficult to obtain an ideal equipotential surface area, in which different equipotential lines are regularly formed, and the accuracy of coordinate positions is reduced.

The purpose of the present invention is to eliminate these drawbacks.2 A conductive film is placed between two resistive films, and when a potential is applied to this conductive film and pressure is applied with a writing instrument, a flow from the conductive film flows through the two resistive films. To detect the current value, it is necessary to embed a conductor in each of the two resistive films to detect the value of the pressurized point. It is characterized by maintaining high accuracy, and will be explained in detail below.

FIG. 2 is a configuration diagram of an input panel showing an embodiment of the present invention, in which 16 is an insulating film, 17.21 is a resistive film, and 18° and 20 are pressure-sensitive rubber ( 19 is a conductive film, and 22 is an insulating substrate. Note that the insulating film 16. Resistive film 17. The conductive film 19 is made of a flexible material, and as shown in detail in FIG.
It has a configuration in which 30 forces and 1 are embedded. Also, resistive film 17
A terminal conductor 28 is provided at the tip of the terminal conductor 28 , and is connected to a switch 48 through an upline 41 . 81) 1 Writing instruments such as ballpoint pens and mechanical pencils.

A general writing tool such as a pencil will suffice. Reference numeral 82 indicates a point pressurized by the writing tool 31, that is, a pressure point. The resistive film 21 also has a configuration in which two thin conductors 84 to 40 are embedded in the horizontal direction, and the terminal conductor 8 is located between the upper end I''' and t of the resistive film 21.
A terminal conductor 88 is connected to the switch 48 through the upline 42. Note that the common terminal of switch 48 is connected to line 44 to input I/.

FIG. 4 is a wiring diagram to more clearly illustrate the operation of the present invention, and pressure sensitive rubbers 18 and 20 on the input panel are omitted for simplicity. Reference numeral 45 denotes a DC power source which is a constant voltage source, and its positive side is connected to the conductor film 19 and its negative side is grounded. 46 is a resistor whose one end is connected to the line 44 and the other end is grounded.

47 indicates an analog-to-digital converter.

When pressure is applied to a point 82 on the input panel by the writing instrument 81, the entire area is pressurized through the insulating film 16, and the resistive film 17 comes into contact with the conductive film 19 at the pressure point 32 through the pressure-sensitive rubber 18, and at the same time, the conductive film 19 The pressure sensitive rubber 20 connects the resistive film 21 and the pressure point 82.
Contact with. In this way, the pressure sensitive rubber 1 is
A potential is applied to the pressure point 82 of the resistive film 17.21 through 8.20. This potential is the potential of the DC power supply 45.

To explain the case where the thin conductors 24 to 30 do not exist, generally when a potential is applied to one point 32 of the resistive film 17, a certain voltage is derived at the terminal conductor 28, but since the current flows over the entire resistive film. , and the vertical distance from the pressurizing point 32 to the terminal conductor 23, and the pressurizing point 32 and the terminal conductor 2
Since the resistance values between the pressure points 32 and the terminal conductors 28 are not in a proportional relationship, it is not possible to calculate the resistance values between the pressurizing points 32 and the terminal conductors 28 from the voltage derived to the terminal conductors 28 using a simple formula.

Here, the voltage of the DC power supply 45 is E, the potential derived from the line 44 is ■, and the resistance value between the pressurizing point 32 and the terminal conductor 23 is D.
The resistance value of the resistor 46 is measured from the R2 pressurizing point 82 to the resistive film 17. Since the current flows through the switch 48 and the resistor 46, -V r = RX - ■ This resistance value r means the sheet resistance between the terminal conductor 28 and the pressure point 32. There is no proportional relationship with the distance, and the surface that can serve as a resistor is not a quadrilateral, but changes in a complicated manner depending on the position of the pressurizing point 32. Therefore, the distance from the terminal conductor 28 to the pressurizing point 32 cannot be easily calculated.

The present invention has been made in view of the above points, and the resistive film 1
By embedding a plurality of thin conductors 24 to 8o at equal intervals in the vertical direction in 7, it is possible to apply calculations considering the sheet resistance as a quadrilateral. That is.

In FIG. 8, when the pressure point 32 is pressurized by the writing instrument 81, a potential E is applied to the pressure point 82 and a current (
Let this be et al. ) flows. The current path from the pressurizing point 32 to the thin conductor 29 is not quadrilateral, but once the current reaches the thin conductor 29, the current passes from the thin conductor 29 to the terminal conductor 28.
It flows uniformly over the surface of the resistive film 17 toward the direction of the direction. There is no problem if the current is approximated as flowing in a small area up to the conductor 29, which is thinner than the pressurizing point 32. The details of how this small range is selected are omitted because it is considered unnecessary for explaining the present invention.

In this way, the potential led out to the switch 48 is V□.

The resistance value between the pressurizing point 32 and the terminal conductor 23 is r　pressurizing X.

From point 82, resistive film 17. Switch 43. If the current flowing through the resistor 46 is i, then r2 gives the X coordinate on the input panel. however.

When converting the input board L to the X coordinate from DE, divide 72 by the resistance value between the thin conductors, add the remainder of the division with a slight correction and r, and subtract the remainder from there. It is necessary to use the new value for r. Resistive film 21
The resistive film 17 also has the same structure as the resistive film 17, and the difference is that the resistive film 17 gives two coordinates, whereas the resistive film 21 gives a V coordinate. As explained above, from the pressurizing point 32 pressurized by the writing instrument 31, the current is led out to the line 41 for the two axes and the line 42 for the V axis, and is switched by the switch 48 to the line 4.
4 to resistor 46. Analog-to-digital converter 47 is for converting the voltage derived on line 44 into a digital quantity.

As explained above, in the above embodiment, a conductive film is placed between two resistive films, pressure-sensitive rubber is placed between the conductive film and the resistive film, a potential is applied to the conductive film, and pressure is applied with a writing instrument to form the conductive film. Since the value of the current flowing through two resistive films is detected, there is no need for a connection cord on the person's wall, and an ordinary writing instrument can be used, improving operability.Additionally, it has the advantage of being able to input notes from inside the handle. be.

An even greater advantage is that since a plurality of thin conductors are provided at equal intervals on the two resistive films, the current path becomes clear and an ideal equal current circuit can be obtained.

In the embodiment described above, a pressure-sensitive rubber 18. is provided between the resistive film 17.21 and the conductive film 19, which is electrically connected between the upper and lower pressure points by applying pressure.
20 was used, but the resistive film 17. Depending on the material of the conductor film 19,
If spacers with appropriate thickness are placed on the four sides of the periphery instead of the pressure-sensitive rubber 18.20, the resistive film 17.21 will remain as long as no pressure is applied.
Since the conductor film 19 does not come into contact with the conductor film 19, no pressure-sensitive rubber is required, and a coordinate input device can be provided at a lower cost.

Further, in the above embodiment, the insulating film 16. Resistive film 17.21° The insulating substrate 22 has been explained as separate components to make the explanation easier to understand, but it is better to make the insulating film 16 and the resistive film 17 integral and configure the resistive film on the back surface of the insulating film 16. The process is simpler. Similarly, regarding the resistive film 21 and the insulating substrate 22, if the resistive film is formed on the insulating substrate 22, the process will be simplified.

Furthermore, in the above embodiment, the resistance value between the pressure point and the terminal was calculated from the difference in current value, but by using the DC power supply 45, which is a constant voltage source, as a constant current source, the resistance value between the pressure point and the terminal can be calculated. It is also possible to directly read the resistance value in the form of voltage, and the present invention not only converts the current value into a resistance value, but also allows the resistance value to be directly read.

As explained in detail above, the present invention has a configuration in which a plurality of fine conductors are embedded at equal intervals in a resistive film, thereby making it possible to obtain an ideal equal-current circuit without current wrap-around, thereby allowing highly accurate coordinate input. Devices can be configured. In addition, there is no need for a connection cord to the writing instrument, and this combined with the advantage that input can be made while taking notes, makes it possible to use it not only in keyboards but also in fields such as input panels for online character recognition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional coordinate input device.
FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 8 is a detailed diagram of a resistive film, and FIG. 4 is a wiring diagram of an embodiment of the present invention. ! ...Resistance film closely adhered to insulating plate, 2-0.
AC power supply, 3 to 6...Diode group, 7 to 1
0...terminal group, 11...pen, 12. i
s...diode. 14.15...Terminal, 16...Insulating film,
17, 21... Resistive film, 18.20... Pressure sensitive rubber, 19... Conductor film. 22... Insulating substrate, 21.88... Terminal conductor, 24-80. 84-40... Thin conductor, 8
1... Writing implements. 82...pressure point, 41,42.44...line,
48...Switch, 45...DC power supply, 4
6...Resistor, 47/analog/digital converter. Patent applicant Oki Electric Industry Co., Ltd. Patent application agent Megumi Yamamoto - Figure 2 Figure 4

Claims (1)

[Claims] It has an input panel and a pressurizing body that selectively pressurizes the input panel,
In a coordinate input device that outputs coordinate information of a pressurized position as an electrical signal, an input board is provided on an insulating substrate in close contact with it, and has a plurality of long, thin straight conductors parallel to each other at predetermined intervals. A first resistive film embedded therein and a second resistive film embedded with a plurality of other elongated linear conductors parallel to each other at predetermined intervals in a direction orthogonal to the linear conductor are tightly attached to the lower surface. It has a flexible insulator, a flexible conductive film, and a pressure-sensitive rubber film or a gap provided between a first resistive film and the conductive film and between a second resistive film and the conductive film. It is characterized by Coordinate input device using a conductor-embedded resistive film.