JPS6130289B2 - - Google Patents

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 for inputting characters or 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 1 is a resistive film closely attached to an insulating plate, 2 is an AC power source, and 3, 4, 5, and 6 are diode groups. The anodes of the diode group 3 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 3 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, 9, and 10 are terminal groups provided on the resistive film 1, terminal group 7 is connected to the cathode of diode group 3, terminal group 8 is connected to the anode of diode group 4, and terminal group 9 is connected to the diode group 3. The terminal group 10 is connected to the cathode of group 5, and the terminal group 10 is connected to the cathode of group 5.
connected to the anode of 11 is a pen, 12 and 13 are diodes, and 14 and 15 are terminals. Diode 1 is connected by a conductor from the tip of pen 11.
The anode of diode 12 connected to the cathode of diode 2 and the anode of diode 13 is connected to terminal 14,
The cathode of diode 13 is connected to terminal 15.

Therefore, when one point on the resistive film 1 is pressurized by the pen 11, when the AC power supply 2 is negative, the diode groups 3 and 4 are cut off, and the diode groups 5 and 6 are cut off.
becomes conductive. Therefore, the 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 AC power supply 2 is positive, diode group 5
and 6 are cut off, diode groups 3 and 4 become conductive, and the positive voltage at the pressure point is transmitted to the pen 11, and a positive voltage corresponding to the pressure point is outputted to the terminal 15 through the diode 13. Here, terminal groups 7 and 8 are installed at opposite ends of the resistive film 1 in the Y direction, and terminal groups 9 and 10 are installed at opposite ends of the resistive film 1 in the X direction. The negative voltage derived represents the X-axis coordinate and is applied to terminal 15.
The positive voltage derived from , means the coordinate of the Y axis. In this way, the coordinates of both the X and Y axes are detected,
In the conventional coordinate input device, 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.

Therefore, the input pen has a serious drawback of requiring a connection cord and having poor operability. Furthermore, the coordinate input device has an unacceptable drawback in that it is not possible to place a form between the input panel and the input pen, and it is not possible to make a copy of the characters input into the handwritten character input device. A method has also been proposed in which the coordinate position is detected by capacitive coupling, rather than by conduction, in order to insert forms between the input panel and the input pen and take notes while inputting, but in order to detect minute signals, peripheral circuits are required. However, it could only be expensive and impractical.

Furthermore, in the case of the above coordinate input device, opposing electrodes in the X and Y directions are formed on one resistive film, so when a voltage is applied between one terminal group, the voltage is applied between the terminal groups to which no voltage is applied. There was also a serious drawback that the current wrap-around phenomenon occurred, making it difficult to obtain an ideal equipotential surface, that is, a surface in which different equipotential lines were regularly formed, and that the accuracy of coordinate position was reduced.

The purpose of the present invention is to eliminate these drawbacks.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 to the two resistive films is generated. The position of the pressurizing point is detected by detecting the current value, and 2
It is characterized by embedding a conductor in each of the resistive films to construct an ideal equal current circuit, thereby maintaining high accuracy in coordinate position, and will be described 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 and 21 are resistive films, and 1
8 and 20 are pressure-sensitive rubbers (rubber that becomes conductive when pressurized) that conduct between the upper and lower pressure points when pressurized; 19
is a conductive film, and 22 is an insulating substrate. The insulating film 16, the resistive film 17, and the conductive film 19 are made of flexible materials, and as shown in detail in FIG.
30 is embedded. Further, a terminal conductor 23 is provided at the tip of the resistive film 17, and is connected to a switch 43 through a wire 41 stranded from the terminal conductor 23. 31 is a writing instrument, which may be a general writing instrument such as a ballpoint pen, sharp pencil, or pencil. 32 indicates a point pressurized by the writing instrument 31, that is, a pressure point.
The resistive film 21 also has thin conductors 34 to 40 embedded in the horizontal direction, and a terminal conductor 33 is provided at the upper end of the resistive film 21, and the terminal conductor 33 is connected to a switch 43 through a stranded wire 42. Ru.
Note that the common terminal of the switch 43 is connected to the line 44.

FIG. 4 is a wiring diagram to more clearly show the operation of the present invention, and the pressure sensitive rubbers 18 and 20 of 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-digital converter.

When pressure is applied to one point 32 on the input panel by the writing instrument 31, the entire area is pressurized through the insulating film 16, and the resistive film 17 is connected to the conductor film 19 by the pressure-sensitive rubber 18 and the pressure point 3.
At the same time, the conductive film 19 contacts the resistive film 21 at the pressure point 32 through the pressure-sensitive rubber 20. In this way, a potential is applied by the conductor film 19 to the pressure points 32 of the resistive films 17 and 21 through the pressure sensitive rubbers 18 and 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 23, 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 resistance value between the pressurizing point 32 and the terminal conductor 23 are not in a proportional relationship, so the voltage derived from the terminal conductor 23 is It is not possible to calculate the resistance value between the two using a simple calculation formula.

Here, the voltage of the DC power supply 45 is E, the potential led to the line 44 is V, the resistance value between the pressure point 32 and the terminal conductor 23 is r, the resistance value of the resistor 46 is R, and the pressure point 3
2, if the current flowing through the resistive film 17, switch 43, and resistor 46 is i, then i=V/R=E-V/r, so r=R×E-V/V, but this resistance value r is determined by the applied pressure. Since it means the sheet resistance between the point 32 and the terminal conductor 23, it is not proportional to the distance from the terminal conductor 23 to the pressurizing point 32, and furthermore, the surface that can be a resistor is not a quadrilateral, but a surface resistance between the pressurizing point 32 and the terminal conductor 23.
It changes in a complicated manner depending on the position of the . Therefore, the distance from the terminal conductor 23 to the pressurizing point 32 cannot be easily calculated.

The present invention has been made in view of the above, and it is possible to apply calculations considering the sheet resistance as a quadrilateral by embedding a plurality of thin conductors 24 to 30 vertically in the resistive film 17 at equal intervals. It is something to tighten. That is, in FIG.
When pressurized, a potential E is applied to the pressurizing point 32, and a current (this is designated as i _x ) flows through the terminal conductor.
Although the current path from the pressurizing point 32 to the thin conductor 29 is not quadrilateral, the current _i flows. There is no problem if the current i _x is approximated as flowing through 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 43 is set to V
_x , the resistance value between the pressure point 32 and the terminal conductor 23 is r _x ,
If the current flowing from the pressurizing point 32 through the resistive film 17, switch 43, and resistor 46 is i _x , then i _x = V _x /R=E-V _x /r _x , so r _x = R x E-V _x / V _x and r _x gives the x coordinate on the input panel. However, when converting r _x to the x coordinate on the input panel, divide r _x by the resistance value between thin conductors, add the remainder of the division with a slight correction, and r _x , and then use the above It is necessary to create a new r _x with the value obtained by subtracting the remainder. The resistive film 1 attached to the resistive film 21
The structure is the same as that of 7, and the difference is that the resistive film 17 gives the x-coordinate, whereas the resistive film 21 gives the y-coordinate. As explained above, the current flows from the pressure point 32 applied by the writing instrument 31 to the line 41 on the x axis.
The shaft is led out to a line 42, switched by a switch 43, and flows through a line 44 to a 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. Because the input pen detects the current value flowing through the two resistive films, no connection cord is required for the input pen, and an ordinary writing instrument can be used, which improves operability and has the advantage that input can be made while taking notes.

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, pressure-sensitive rubbers 18 and 20 were used between the resistive films 17 and 21 and the conductive film 19, which are electrically connected between the upper and lower pressure points by applying pressure. If spacers with an appropriate thickness are placed on the four sides of the periphery instead of the pressure rubbers 18 and 20, the resistive films 17 and 21 and the conductive film 19 can be removed as long as no pressure is applied.
Since there is no contact between the two, pressure-sensitive rubber is not required, and a coordinate input device can be provided at a lower cost.

Further, in the above embodiment, the insulating film 16, the resistive films 17, 2
1. Although the insulating substrate 22 has been described as a separate component for the sake of clarity, it is easier to process the insulating film 16 and the resistive film 17 by making them integral and forming the resistive film on the back surface of the insulating film 16. Become. 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, since there is no need for a connection cord to the writing instrument, and furthermore, it is possible to input while taking notes, it can be widely used 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. 3 is a detailed diagram of a resistive film, and Fig. 4 is an embodiment of the present invention. FIG. 1...Resistive film closely adhered on an insulating plate, 2...AC power supply, 3-6...Diode group, 7-10...
Terminal group, 11... Pen, 12, 13... Diode, 14, 15... Terminal, 16... Insulating film, 1
7,21...Resistive film, 18,20...Pressure sensitive rubber,
19... Conductor film, 22... Insulating substrate, 23, 33
...Terminal conductor, 24-30, 34-40... Thin conductor, 31... Writing instrument, 32... Pressure point, 41,
42, 44... line, 43... switch, 45...
DC power supply, 46...resistor, 47...analog-digital converter.

Claims (1)

[Claims] 1 In a coordinate input device that has an input panel and a pressurizing body that selectively pressurizes the input panel, and outputs coordinate information of a pressurized position as an electric signal, the input panel has an insulating substrate and an approximately a first resistive film in which a plurality of elongated straight conductors are embedded in close contact and are parallel to each other at predetermined intervals; A flexible insulator having a second resistive film in which a plurality of linear conductors are embedded is substantially adhered to the lower surface; A pressure-sensitive rubber film or a gap is provided between the resistive film and the conductor film, and a terminal conductor is provided at one end of the first and second resistive films and connected in series with each of the straight conductors. A coordinate input device using a conductor-embedded resistive film, characterized in that: