JPS6367621A - Information input tablet - Google Patents

Abstract

PURPOSE:To detect coordinates with high accuracy at a low cost by dividing electrically and geometrically the resistance film of the 1st and 2nd substrate. CONSTITUTION:An electrode is provided between two electrodes 7 and 8 to perform the electrical and geographical division between both electrodes 7 and 8. Thus the inter-electrode distance is effectively reduced and therefore the detecting error is reduced. In other words, a resistance film 3 is formed on a single side of the 1st substrate 1 and the stripe-shaped conductive electrodes, i.e., the (y) coordinate detecting electrodes 4 are provided equidistantly on the film 3. As a result, the film 3 is divided electrically and geometrically into plural pieces. While a film 3 is also formed in a signal side of a substrate 2 and a stripe conductive electrode, i.e., an (x) coordinate detecting electrodes 5 are provided equidistantly on the film 3. Thus this film 3 is divided electrically and geometrically divided into plural pieces. Then both electrodes 1 and 2 are set opposite to each other via a spacer 6 so that both film 3 confront with each other and electrodes 4 and 5 are set orthogonal to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an information human-powered tablet, and particularly to the structure of a resistive film in a resistive film type.

(Prior Art) Coordinate detection methods for information input tablets generally include a resistive film method, an electromagnetic induction method, an electrostatic induction method, a pressure sensor method, and an optical method. Comparing these detection methods, the resistive film method is the most superior in terms of cost.

In this resistive film method, an information input tablet is constructed by combining a first substrate and a second substrate on which a resistive film with electrodes at both ends is formed, with each resistive film on the inside and the positions of the electrodes being orthogonal to each other. are doing.

A conventional example of such an information input tablet is shown in FIGS. 3 and 4. That is, the electrode 7 of the resistive film 3 on the first substrate 1
．． 8 is connected to a constant current source or a constant voltage source. Then, when a voltage is applied to the first substrate 1 and pressure is applied to the first substrate 1, each resistance film 3 of the first substrate 1 and the second substrate 2 comes into contact with each other, and the resistance film 3 of the second substrate 2 comes into contact with the resistance film 3 of the second substrate 2. is the current IX1. depending on the distance of the electrode 7.8 from the point of contact P. IX2 flows respectively. The X coordinate of the contact position is detected based on the ratio of the magnitudes of this current. Further, the X coordinate can be detected by connecting a constant current source or a constant voltage source to the second substrate 2 and detecting the current using the electrodes 9 and 10 on the first substrate 1.

(Problem to be solved by the invention) In the resistive film method as described above, the distance from the contact point to the electrode and the resistance value must be directly proportional, and for this purpose the resistive film must be uniform. . However, in reality, since the resistive film is non-uniform, errors occur and the accuracy decreases, resulting in a problem that the accuracy is inferior to the electromagnetic induction method or the electrostatic induction method.

This invention was made in view of reports that detection accuracy in resistive film methods deteriorates due to non-uniformity of the resistive film, and an object of the present invention is to provide an information input tablet that enables high-precision coordinate detection at low cost. purpose.

[Structure of the Invention] (Means for solving the problem of source points) In order to minimize the deterioration in precision due to non-uniformity of the resistive film, the present invention provides This information input tablet is formed by electrically and geometrically dividing at least one of the resistive films.

(Function) According to the present invention, since the resistive film is electrically and geometrically divided, detection accuracy can be significantly improved. As a result, a highly accurate information input tablet can be provided at low cost. Further, the present invention can also be expected to have an effect of reducing noise.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

First, using FIGS. 3 to 5, a method for detecting coordinates using a resistive film method will be discussed regarding the X coordinate.

That is, it is assumed that the respective resistive films 3 of the first substrate 1 and the second substrate 2 come into contact at a point P, as shown in FIGS. 3 and 4. In addition, the first unit! It is assumed that the resistive film 3 of 21 is at the potential. At this time, currents IX1 and IX2 as shown in FIG. 5 flow from point P into electrode 7 and electrode 8, respectively. If the distance between the resistive film 3 between the electrode 5 and the electrode 4 is D, then the X coordinate will be when the resistive film is uniform.

Next, consider the case where the resistive film is non-uniform. The resistance per unit length of the portion where the current IXt flows and the portion where the current IX2 flows are expressed by ρ and k·ρ, respectively. Note that when the resistive film is uniform, it is k-1. Letting the X coordinate at this time be X', it becomes jX10K''IX2.The error xK is the difference between the correct X coordinate X' and the X coordinate X that includes an error that does not take into account nonuniformity of the resistive film, and is From equations 1) and (2), xK- (3) and xK can be found.As is clear from the above equation, in order to reduce the detection error, it is necessary to make k sufficiently close to 1. , or it is necessary to reduce D.

Therefore, by providing an electrode between electrode 7 and electrode 8, the space between the electrodes can be electrically and geometrically divided, and the distance between the electrodes can be effectively shortened, thereby reducing detection errors. .

Therefore, the information input tablet according to the present invention is shown in Fig. 1 (
It is constructed as shown in Figures a), (b) and m2, and Figures 1 (a) and (b) are a cross-sectional view and a plan view, and Figure 2 is a
This is a comparison of the boards.

That is, a resistor H3 is formed on one surface of the first substrate 1, and a striped conductive electrode, that is, an X-coordinate detection electrode 4 is formed on this resistive film 3.
By providing the resistive film 3 at equal intervals, the resistive film 3 is electrically and geometrically divided into a plurality of (at least two or more) parts. Further, a resistive film 3 is formed on one surface of the second substrate 2, and by providing striped conductive electrodes, that is, X-coordinate detection electrodes 5 at equal intervals on this resistive film 3, the resistive film 3 It is electrically and geometrically divided into a plurality of parts (at least two or more). The first substrate 1 and the second substrate 2 are arranged at a predetermined interval with a spacer 6 in between so that the resistive films 3 face each other and the electrodes 4.5 are perpendicular to each other.

In the above case, at least one of the first substrate 1 and the second substrate 2 is transparent, and at least one of the resistive films 3 formed on the first substrate 1 and the second substrate 2 is transparent.

Now, in order to manufacture a transparent tablet as an example of such an information input tablet, glass substrates are used as the first substrate 1 and the second substrate 2, and the first substrate 1 and the second substrate 1 are
A resistive film 3 is formed on a substrate 2. As the resistive film 3, I
A transparent resistive film such as TO (indium tin oxide) is used. On this resistive film, electrodes 5 made of aluminum or the like are formed in a striped manner at equal intervals. At this time, the width of the electrode 5 needs to be sufficiently narrow compared to the resolution required for the information input tablet. Furthermore, if the manufacturing of the electrode 5 causes a problem of errors due to loss of flatness, the ITO electrode portion may be removed by etching or the like in advance. The thus produced substrates are combined so that the electrodes 5 are orthogonal to each other as shown in FIG. 5 to construct an information input tablet.

Next, coordinate detection will be explained.Here, only the X coordinate will be explained, but for the X coordinate, the relationship between the electrode 4 on the first substrate 1 and the electrode 5 on the second substrate 2 can be swapped. . First, a constant voltage source is connected to the electrode 4 on the first substrate 1, and the resistive film 3 on the first substrate 1 is kept at a constant potential. When pressure is applied to the first substrate 1 and the resistive films of the first substrate 1 and the second substrate 2 come into contact, the electrode 5 of the second substrate 2 is selected and the current is measured. In this case, one or more electrodes are selected from the group of five electrodes. Here, as an example, a case will be considered in which two electrodes are selected, shifted one by one from the left side, and the current is measured, and the other electrodes are not connected.

From among the sets of currents measured in each case, the case where the contact point is between the two electrodes is selected, and the coordinates are determined by taking the ratio of the currents. At this time, the coordinates are detected within the divided portions, improving accuracy. Furthermore, the coordinates of the contact point are detected by time-divisionally detecting the X coordinate and the X coordinate.

[Effects of the Invention] According to the present invention, when manufacturing a resistive film type information input tablet, since the resistive film 3 is electrically and geometrically divided, detection accuracy can be significantly improved. As a result, a low-cost, highly accurate information tablet can be obtained.

Further, the present invention can also be expected to have an effect of reducing noise.

[Brief explanation of the drawing]

1(a) and (b) are a cross-sectional view and a plan view showing an information input tablet according to an embodiment of the present invention, and FIG. 2 is a plan view showing a second substrate of the information input tablet of the present invention taken out. , Figure 3 is a plan view showing a conventional information tablet;
FIG. 4 is a cross-sectional view taken along line AA' in FIG.
FIG. 5 is an explanatory diagram of the operation of the resistive film type information input tablet. 1... First substrate 2... fJ2 substrate 3... Resistive film 4... Electrode for X coordinate detection 5... Electrode for X coordinate detection 6... Spacer applicant's agent Patent attorney Takehiko Suzue 2 Figure 4 Figure 5

Claims (4)

[Claims] (1) A first substrate on which a resistive film having electrodes is formed, and a second substrate
An information input tablet comprising substrates disposed at predetermined intervals such that the resistive films face each other and the electrodes are orthogonal to each other, the resistive film of at least one of the first substrate and the second substrate being electrically An information input tablet characterized by geometric division. (2) The information input tablet according to claim 1, wherein at least one of the first substrate and the second substrate is transparent. (3) The information input tablet according to claim 1, wherein at least one of the resistive films is transparent. (4) The resistive film is electrically and geometrically divided into at least two parts by providing striped conductive electrodes at equal intervals on the resistive film. Information input tablet as described in section.