JPS5887671A - Detecting plane for diagram reader - Google Patents

Abstract

PURPOSE:To sufficiently improve the accuracy of detection of a detecting plane comprising a flat resistance body, by providing a surface resistance reduction means compensating the increase in resistance value due to the edge effect for a pair of edges where no signal reading electrode is provided. CONSTITUTION:Coordinate position signal readout electrodes 2, 3 are provided at a pair of ridges opposing with each other of a flat resistance body 1, and a pair of ridges where no electrodes 2, 3 are provided is provided with a point electrode 5 along the prolonged direction. A resistor 6 is connected between two electrodes 5 adjacent with each other, and the resistor reduces the surface resistance of the ridges of the resistor 1. As a result, the increase in the resistance at the ridge can be cancelled, and the dependancy of the resistance value from an arbitrary point on the surface of the resistor 1 to the electrode 2 on the Y coordinate can be compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a figure reading device which is used as an input device of an electronic computer system and uses a pen-shaped indicator to read coordinates indicated on a plane in real time and give a signal. Regarding the detection surface.

Conventionally, such graphic reading devices have been known based on various operating principles such as electromagnetic type and acoustic type.
Devices constituting the detection surface for this purpose include magnetostrictive devices for electromagnetic methods and surface acoustic wave devices for acoustic methods, which are known or are dangerously used.

However, all of these devices have fairly complex structures and are expensive, and there is a problem in that increasing the accuracy of headlight detection further increases the cost.

Therefore, in order to solve this problem, a sensing surface using an ohmic device using a capacitive coupling method was proposed.

This type of ohmic device uses the current that flows when a human finger is pressed against a flat resistor, and detects the position where the finger is pressed by the current value at each electrode of the current flowing at that time. For example, “
In 1970, Spri was introduced as ``touch panel method''.
ng Joint Cow-puter Con
fer@nce K has been announced.

Figure 1 shows a nine-dimensional structure composed of such ohmic devices.
This figure shows an example of a detection surface in the dimensional direction coordinate (X direction), where 1 is a planar resistor, and 2.3 is an electrode for signal extraction.

The planar resistor 1 is made of, for example, a rectangular glass substrate such as a square or a rectangle. A pair of electrodes 2.3 are formed by vapor deposition of metal or gold such as tin oxide.

When a human finger or the like touches an arbitrary point P on the surface of the flat resistor 1, a current I flows from the fingertip to a point P through induction into the flat resistor l, and a current M flows from the electrode 2.3. , flows to ground as IB. Therefore, by utilizing the fact that the magnitude of the currents IA and I at this time changes depending on the distance IA from electrode 2 to point P and the distance IH from electrode 3 to point P, we The coordinate X1 is determined.

Now, in this FIG. 1, the distance tX0 between the electrodes 2.3
, these electrodes 2 , 3 O length t Yo , :' P
0 where the X and Y coordinates of the point are xl, y, respectively
Furthermore, if the resistance distribution of the resistor 1 is uniform and the respective resistance values from point P to each electrode 2.3 are independent of the Y coordinate value Y0 of point P and are determined only by the X coordinate value Then, the equivalent circuit of FIG. 1 becomes as shown in FIG. 2.

Here, 7 people, IB is the perpendicular distance from point P to electrode 2.3, RA r RB is the resistance value from point P to electrode 2.3, 0, and the resistance values RA and RB are the distance I
A and IB are proportional to each other, and current □ and IB are inversely proportional to the resistance value. That is, RA=to@/A=KX, ・・・・・・・・・(1
)RB2 to 11jB-K(xo-X, 1)-(2) Therefore, the X coordinate value X8 of point P is given by the relational expression RA+KB. By measuring the current values I and IB flowing from the electrodes 2.3 and 2.3, the xi target value X1 at point P can be determined since X6 is known.

By the way, in the above explanation, it is assumed that the perpendicular distance IA, jB from point P to the electrode 2.3 and the resistance value RA * RB are in the relationship of equations (1) and (2), but in reality,
Due to the fact that the dimension of the planar resistor 1 in the X direction is finite, the above equations (1) and (2) do not hold true. This is because the electric field is greatly distorted due to edge effects in a finite field.

As a result, if the Y coordinate of point P changes, the relationship between the currents Im and IB will change even if the This means that you will not be able to do so.

To further explain this point, first, the configuration shown in FIG.
If the resistor 4 in g) is modeled using a resistor network, and the resistance value RA' from the point P to the electrode 2t is simulated by a computer, results like the 5th H and 6th leaps are obtained. Also, this has been confirmed by experiment.

As is clear from FIGS. 5 and 6, even if the X coordinate value X1 of point P is constant, if the Y coordinate value Y8 changes, P
The resistance value R4 from the point to the electrode 2 changes, and the rate of change also changes depending on the X coordinate values X and K.

And, as understood from No. 6 #A, the linear distance from point P to electrode 2! If the X1 coordinate of point j7P and the resistance value Rm are given by a single straight line regardless of the Y coordinate value Y, even if an error tube of about 10qII is allowed, 3≦X1≦10, And it can only be obtained within the range of 3≦Y1≦7.

Therefore, the detection surface using the nine conventional ohmic devices shown in FIG. 1 has the disadvantage that coordinates can only be detected accurately in the central portion of the planar resistor 1.

An object of the present invention is to eliminate the drawbacks of the prior art described above, improve the coordinate detection accuracy on the detection surface of a figure reading device configured with an ohmic device, increase the effective detection area, and provide a high-precision detection surface at low cost. It is on offer.

In order to achieve this object, the present invention provides a method for detecting a signal reading electrode between two pairs of opposing edges of a rectangular planar resistor serving as a sensing surface. The present invention is characterized in that a sheet resistance value reducing means is provided to compensate for an increase in resistance value due to edge effects.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the drawings will be described as examples of the detection surface for a pattern reading device according to the present invention.

The 7th ffi is an embodiment of the present invention, and the planar resistor 1 and electrodes 2.3 are the same as the 1st Et) conventional example.

In FIG. 7, the point electrode 6 provided at the end of the s#'i planar resistor 1O# is a resistor.

The dotted electrodes 5 are arranged at a predetermined interval along the extending direction of the pair of edge ends of the planar resistor 1 where the electrodes 2.3 are not provided.

Resistor 6 is Iil! It is connected between two point-shaped electrodes 50 that are connected to each other, and thereby serves to reduce the sheet resistance value at the edge of the planar resistor l.

Now, as is clear from FIG. 5, the resistance value R from the point P on the 1,000-meter resistor 1 to the electrode 2 is equal to The closer you get to
It gets expensive. ttb, In Fig. 5, the resistance value Rm when the coordinate value X1 of point P is the value is tkK when the Y coordinate value Y8 is 5.
It is the lowest, and increases as the distance from K increases from 5, that is, as it approaches the edge where the electrode 2.3 is not provided.

However, in the embodiment shown in FIG.
A dot-shaped electrode 5 is arranged, and a resistor 6 is connected to each of the electrodes, and the sheet resistance value of the flat resistor l at the edge part is reduced from the point k, so that the above-mentioned edge part As a result, the dependence on the resistance value RA (DY coordinate value Y1) in the conventional example shown in FIG. 6 can be compensated for, and the characteristics shown in FIG. 8 can be obtained. can.

The characteristics of this No. 8 #lJ are as follows when the resistance value of the edge resistance (resistance on the upper row and the bottom row of No. 4 wA) is 0.3Q in the model shown in Fig. 4. It is something.

As is clear from the 8th @I, according to the embodiment of the 7th tlA, the relationship between the resistance value Rm and the X coordinate value X1 of the point P and oy4 is 2 points 0Y121 over the range of 3≦X1≦100.
Regardless of the H value Y, K can be approximated by approximately one straight line, and the X coordinate value can be detected precisely.

Next, FIG. 9 shows another embodiment of the present invention, in which 7 is a thin film layer of metal or metal oxide provided in a strip shape along the edge of the strip shape;
This serves to reduce the sheet resistance value at the edge of the flat resistor 1.

Therefore, this embodiment also achieves high precision as in the embodiment shown in FIG. 7, and it is easy to manufacture since it does not require point electrodes or resistors, making it possible to reduce costs even further.

By the way, according to the above embodiment, it is possible to perform highly accurate detection by compensating for the dependence of the detection of the X coordinate value X1 on the Y coordinate value Y. However, as can be understood from FIG. Therefore, linearity with respect to the KX coordinate values X and K has not yet been sufficiently obtained.

In other words, in order to accurately determine the x-coordinate 11 10th r
The characteristics of IA must be as shown in ■.

However, since the size of the planar resistor 1 serving as the sensing surface is finite as described above, it is extremely difficult to obtain the characteristics shown in FIG.

Therefore, let's now consider wishing for a characteristic like ■ in Figure 1θ. Then, according to this, 1≦X1≦1
0, and in the range of 0≦Y1≦00, the relationship RA=Kjmu+R0=KX,+R,...(5) is obtained, and similarly for the resistance value RB, RB=KIB +R
.

=K (X6 XI)+Ro ・・・・・・・・・
(6) is obtained.

Further, this is because the resistance value and the current value are inversely proportional.

Next, in the coordinate system (RA,
A new coordinate system (R
A*X'1) t-Think. Then, this (
The coordinates (RA e X'S ) are shifted by a line segment a in the left direction of the (RA,

Therefore, X'l = a + X 1 --------
- (8).

Therefore, equations (5) and (6) are used for this new coordinate (RAT
If expressed as
5) 'RB = KIB' = K (X6+a X'1)
(6)', and as a result, (η equation becomes).

Next, in the same way as when determining the X-coordinate 41IK of point P in FIG. 1, the coordinates of the point IOP of the planar resistor IOP shown in FIG. 11 are determined using all new coordinates (X', Y). If the X' coordinate value of point P at this time is X'1, then the following equation is obtained.

By substituting equation (8) into equation (9), (X
.

Y) An X coordinate value X8 in the coordinate system is obtained.

This equation (10) is calculated by calculating at from the relationship between RA and
This shows that by measuring t, the X coordinate value X1 of point P can be uniquely determined.

Therefore, by using a planar resistor 1 of a finite size,
As shown in the characteristic, the resistance value from point P to electrode 2.3 is Y
In order to make it proportional only to the distance j regardless of the coordinate value, it may be done as shown in FIG. 12, for example.

This FIG. 12 is also an embodiment of the present invention, and the planar resistor 1, electrodes 2.3, and band-shaped resistive film 7 are the same as those in the embodiment of FIG.

In FIG. 12, reference numeral 8 indicates a point electrode provided at the edge of the planar resistor 1, and reference numeral 9 indicates a resistor connected between the point electrode 8 and the electrode 2.degree.

As already explained, in the embodiment shown in FIG. 7 or 9, as the point P approaches the electrode 2 and K, the change state of the resistance value RA changes from a straight line, as is clear from the characteristics shown in FIG. At the same time, the resistance value RA at the -X coordinate value X1 changes depending on the Y coordinate value Y1 of the P point.

This is because as the point P approaches the electrode 2, the current flowing into the planar resistor IK becomes concentrated on the drawing line connecting the point P and the electrode 2t. (in the figure, the current flows almost uniformly in the Y direction in the planar resistor 1 near the electrode 50).

The degree of concentration of current at this time is one line larger when point P is on the central part oti,m of the electrode, and is the smallest when point P is on the perpendicular line to the end O of the electrode.Therefore, P If the point is close to the electrode and the current flows almost uniformly through the flat resistor lO, the relationship between the resistance value RA and the X coordinate value X1 at this part is the same as in the other parts. Therefore, as shown in the 12th vA, the electrodes 2 and 3 are separated from the edge of the planar resistor l, and the resistor 9 is connected to the point electrode 8 provided on the edge of the plane resistor l. The resistance values of these resistors 9 are made to have a maximum value at the center of the planar resistor 1 and a minimum value at both ends. In addition, at this time, k is set so that the minimum value ([] is also larger than the unit resistance value of 10 planar resistors.

In this way, the above-mentioned concentration of current can be prevented, and the characteristics shown in the 13th EK can be obtained.

As is clear from comparing the characteristics of the #glt)4I characteristics in Figure 13 and the characteristics of the Jls diagram, it is clear that the example shown in Figure 12 provides a much wider linear range. In the above example, only the P point OX coordinate direction was shown, but in reality, by combining the planar resistor tai that detects the Y coordinate direction, the X and Y coordinates can be sufficiently enlarged. It is customary to make the detection impossible.

Even if the current flows from point P, K, in the above embodiment, the DC current tw! In practice, it is customary to use a piezoelectric sheet or a capacitive coupling method using an AC power supply. It goes without saying that this is possible.

As explained above, according to the present invention, with a simple configuration,
Since the detection precision of the detection surface made of a planar resistor can be sufficiently improved, it is possible to eliminate the drawbacks of the prior art and provide a detection surface for a q-cost figure reading device.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a conventional example of a sensing surface constructed with ohmic devices, Fig. 2 is an equivalent circuit for explaining its operation, Fig. 3 is a schematic diagram for analyzing its operation, and Fig. 4 is a schematic diagram of a sieve. Schematic diagram by, No.! Figure S and Figure 6- are its operating characteristic diagrams, 'NjA is a plan view showing one embodiment of the sensing surface according to the present invention, Figure 8 is its operating characteristic diagram, and Figure 9 EFi is another embodiment of the present invention. 10 is a characteristic diagram for explaining the operation, FIG. 11 is a plan view for explaining the operation, 12th I@1 is a plan view showing still another embodiment of the detection surface according to the present invention, 13th The figure shows the operating characteristics diagram.Ol...
... Planar resistor, 2.3 ... Electrode, 5.8 ...
...Point electrode, 6.9...Resistance, 7...
...Striped resistive film. 71 Order ``l'2 Figure 3 Figure 3 '74 Figure T5 Figure A 4P, Y pressure ya (y) O 6 desired J mi P0 Figure RA RA ?11 Figure σ /

Claims (4)

[Claims] (1) In a detection surface for a figure reader, each of which is provided with an electrode for reading a coordinate position signal on each of a pair of opposing O edge portions of the rectangular planar resistor, the edge of the rectangular planar resistor provided with the electrodes is provided. The term "edge" refers to the other pair of edge sections, each of which is provided with a 0-face resistance value reducing means to reduce the resistance value in the arc length direction of those edge sections, and a coordinate position change in a direction other than the coordinate position detection direction is provided. A sensing surface for a figure reading device, characterized in that it is configured to compensate for detection errors caused by the tube. (2) In claim 1, several point electrodes arranged at predetermined intervals on the other edge of the sheet resistance value reducing means tube and the rectangular resistor, A sensing surface for a figure reading device characterized by comprising a plurality of resistors connected between these point electrodes. (3) In claim 1, the sheet resistance value reducing means is arranged along the other edge of the rectangular resistor and is constituted by a band-shaped resistor. Detection surface for figure reading and placement. (4) In any one of claims 1 to 3, the electrodes for reading coordinate position signals of the rectangular planar resistor are arranged at predetermined intervals along the edge where the electrodes are to be provided, and A plurality of point electrodes and a plurality of resistors connected between each of these point electrodes and the electrode for reading the coordinate position signal are provided, and the resistance value of each of these resistors is measured in the length direction of the edge portion. A detection interval for a figure reading device characterized in that the linearity of the coordinate position signal is improved by decreasing the value sequentially from the center toward both ends of the coordinate position signal.