JP2009151439A - Coordinate input device and driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of a resistive film which occurs when pressing is started in a coordinate input device using the resistive film. <P>SOLUTION: The coordinate input device includes a first substrate which supports a first resistive film, and a second substrate which supports a second resistive film and is disposed so that the second resistive film is opposed to the first resistive film through a space, in which one of the first and second substrate is pressed at a pressing point, and respective parts corresponding to the pressing point of the first and second resistive films are brought into contact with each other to read the coordinate of the pressing point. The coordinate input device further includes a drive circuit for supplying a current to flow between the first resistive film and the second resistive film. The drive circuit continuously increases, when the pressing point is pressed, the value of the current flowing between the first resistive film and the second resistive film at the pressing point from a first value to a second value larger than the first value in accordance with an increase in the contact area between the first resistive film and the second resistive film at the pressing point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally relates to a coordinate input device, and more particularly to a coordinate input device having a resistance film and a driving method thereof.

  With the spread and progress of portable information devices in recent years, electronic notebooks, PDAs (Personal Digital Assistants), mobile phones, PHS, calculators, watches, GPS (Global Positioning System, Global Positioning System, etc.) Coordinate input that is performed by pressing a screen with a pen or a finger in a mobile information processing apparatus, or in a fixed information processing apparatus such as a bank ATM system, a vending machine, or a POS (Point Of Sales) system. The adoption of equipment for man-machine interfaces is expanding.

  In these high-function information processing devices, the miniaturization and multi-functionalization of the devices are progressing due to the advancement of semiconductor technology. The percentage of the housing is increasing.

As such a coordinate input device, a first resistive film in which an electrode pair opposed in the first direction is formed, and a second electrode pair formed in a second direction orthogonal to the first direction are formed. A resistance film and a small distance away from each other, and the first resistance film and the second resistance film are brought into contact with each other by pressing with a pressing tool such as a pen or a finger at one point on the input surface; A coordinate input device (coordinate input device) configured to calculate the X coordinate and the Y coordinate of the contact point by measuring the resistance value of the first resistance film and the resistance value of the second resistance film is proposed. Has been.
JP 2002-109998 A

Since such a coordinate input device using a resistance film is often disposed on a display device such as a liquid crystal display device, ITO (In ₂ O) generally obtained by vapor-depositing In and Sn as a resistance film. ₃ · SnO ₂ ) film or ZnO film or other inorganic conductive film is used as the transparent electrode, but the formation of the inorganic conductive film such as ITO film or ZnO film requires a vacuum process, and the raw material is expensive. There is a problem of high manufacturing cost. In addition, in the coordinate input device using the ITO film, there is a problem that the resistance of the resistance film is easily changed by continuous writing, and the reading accuracy of the coordinate position is lowered.

  Under such circumstances, a coordinate input device using a transparent organic conductive material that is easy to manufacture and inexpensive as a resistance film (conductive film) has been developed.

  However, in the coordinate input device using such a resistance film, when the input surface is pressed by a pressing tool such as a pen and a current flows between the first resistance film and the second resistance film, the first Since the contact area between the first resistive film and the second resistive film is very small at the start of pressing, the current density becomes very large. In particular, at least one of the first and second resistive films is voltage resistant. When a low organic conductive film is used, the organic conductive film may burn out. Further, at the start of such pressing, a large transient voltage is generated at the moment of contact between the first resistance film and the second resistance film, and the resistance film is likely to be damaged.

  According to one aspect, the present invention provides a first substrate carrying a first resistive film and a second resistive film, wherein the second resistive film is in relation to the first substrate. A second substrate disposed so as to face and separate from the first resistance film, and presses one of the first and second substrates at a pressing point, and the first and second substrates In the coordinate input device that reads the coordinates of the pressing point by contacting each portion corresponding to the pressing point in the resistive film, the coordinate input device includes the first resistive film and the second resistive film. A driving circuit for supplying a current flowing between the first resistance film and the second resistance film at the pressing point, and the driving circuit determines the value of the current flowing between the first resistance film and the second resistance film at the pressing point. From the first value according to the increase in the contact area of the second resistive film and the second resistive film, To a second value greater than the first value, to provide a coordinate input apparatus which comprises causing a continuous increase.

  According to another aspect, the present invention provides a first substrate carrying a first resistive film and a second resistive film, wherein the second resistive film is in contact with the first substrate. A second substrate disposed so as to face and separate from the first resistance film, and presses one of the first and second substrates at a pressing point, and the first and second substrates A driving method of a coordinate input device for reading the coordinates of the pressing point by contacting each part corresponding to the pressing point in the resistance film, and when the pressing point is pressed, The value of the current flowing between the first resistive film and the second resistive film is set to a first value according to an increase in the contact area between the first resistive film and the second resistive film at the pressing point. To a second value that is larger than the first value and continuously increasing the coordinate input To provide a driving method of location.

  According to the present invention, in a coordinate input device using an organic conductive film as a resistance film, it is possible to suppress damage to the resistance film at the start of pressing the input surface.

  FIG. 1 shows a configuration of a conventional coordinate input device 40.

  Referring to FIG. 1, a coordinate input device 40 includes a glass substrate 21 carrying a transparent conductive film 32 made of ITO on an upper surface, and a glass substrate 21 facing the glass substrate 21 with a spacer member 23 therebetween. For example, the transparent organic conductive film 42 having a transparent organic conductive film 42 supported on the side facing 21 is formed. The transparent organic conductive film 42 and the transparent conductive film 32 are, for example, 700 μm by the spacer member 23. They are arranged at a certain interval.

  Further, electrode patterns 33A and 34A extending continuously in the X-axis direction are formed on a pair of edges of the transparent conductive film 32 facing in the Y-axis direction, and the electrode pattern 33A is formed on the glass substrate 21. The wiring pattern 33 leads to the terminal portions 33T and 33S on the glass substrate 21. Similarly, the electrode pattern 34 </ b> A is drawn out to the terminal portions 34 </ b> T and 34 </ b> S on the glass substrate 21 by the wiring pattern 34 on the glass substrate 21.

  In addition, electrode patterns 43A and 44A that extend continuously in the Y-axis direction are formed on a pair of edges of the transparent organic conductive film 42 facing in the X-axis direction, and the electrode pattern 43A is formed on the transparent resin substrate. 22 is drawn out to the terminal portions 43T and 43S on the resin substrate 22 by the wiring pattern 43 on the resin substrate 22. Similarly, the electrode pattern 44 </ b> A is drawn out to the terminal portions 44 </ b> T and 44 </ b> S on the glass substrate 21 by the wiring pattern 44 on the transparent resin substrate 21.

  Furthermore, wiring patterns 35 and 38 that contact the terminal portions 43T and 43S on the transparent resin substrate 22 are formed on the glass substrate 21, and the wiring patterns 35 and 38 are formed on the transparent resin substrate 42. The electrode pattern 43A is drawn out to the terminal portions 35T and 38T on the glass substrate 21, respectively. Similarly, wiring patterns 36 and 37 are formed on the glass substrate 21 so as to contact the terminal portions 44T and 44S on the transparent resin substrate 22, and the wiring patterns 36 and 37 are formed on the transparent resin substrate 42. The electrode pattern 44A is drawn out to the terminal portions 36T and 37T on the glass substrate 21, respectively.

  2 and 3 are diagrams showing the operation of the coordinate input device 40 of FIG.

  Referring to FIG. 2, the surface of the transparent resin substrate 22 is pressed by a stylus pen 40P at a certain pressing point (X1, Y1), whereby the transparent organic conductive film 42 carried on the transparent resin substrate 22 is formed. The ITO film 32 carried on the glass substrate 21 is contacted at the pressing point (X1, Y1).

  Therefore, in the state of FIG. 2, the power supply voltage Vcc is supplied to one of the electrodes 43A and 44A, and in the example of FIG. 2A, the other is grounded, and the other is grounded. The voltage drop caused by RX2) is obtained by measuring the potential Vsx of the ITO film 32 that contacts the transparent organic conductive film 42 at the pressing point (X1, Y1). Thereby, the X coordinate of the pressing point is obtained.

  Next, in the state of FIG. 3, one of the electrodes 33A and 34A, in the example of FIG. 2B, the power supply voltage Vcc is supplied to the electrode 33A, the other is grounded, and resistance division (RY1) is performed at the pressing point (X1, Y1). , RYX2) is obtained by measuring the potential Vsy of the transparent organic conductive film 42 that contacts the transparent organic conductive film 42 at the pressing point (X1, Y1). Thereby, the Y coordinate of the pressing point is obtained.

  4 shows a state of contact between the organic conductive film 42 and the transparent organic conductive film 32 when the surface of the resistance film made of the organic conductive film 42 is pressed with a pen in the coordinate input device 40 of FIG. Show.

  Referring to FIG. 4, the organic conductive film 42 is in contact with the transparent conductive film 32 in the area S, and the area S gradually increases as shown in FIG.

  When such contact between the organic conductive film 42 and the transparent conductive film 32 occurs, the current I flowing from the organic conductive film 42 to the transparent conductive film 32 or from the transparent conductive film 32 to the organic conductive film 42 is shown in FIG. ) As shown in FIG. 5B, there may be a case where a large current changes transiently and a large current flows through the organic conductive film 42 instantaneously.

  In addition, since the area S is very small at the initial stage of such a contact, the current density J (J = I / S) of the current I flowing at the pressing point of the organic conductive film 42 is shown in FIG. As shown in FIG. 2, the organic conductive film 42 may be damaged particularly seriously.

  FIG. 6 shows a configuration of a coordinate input device 50 according to an embodiment of the present invention for solving the above problem. However, in FIG. 6, the same reference numerals are assigned to portions corresponding to the portions described above, and the description thereof is omitted.

  Referring to FIG. 6, the coordinate input device 50 has a configuration in which a drive circuit 55 controlled by a CPU 54 is provided in the coordinate input device 40 of FIG. 1, and the CPU 55 is provided in the organic conductive film 42. One of the electrodes 44A and 43A, preferably the electrode 44A opposite to the electrode 43A connected to the drive circuit 55, and one of the electrodes 34A and 33A provided on the transparent conductive film 32, preferably the drive circuit 55 A voltage difference ΔV generated between the connected electrode 33A and the electrode 34A opposite to the connected electrode 33A is read out via the A / D converter 56, and the drive circuit 55 is shown in FIG. 7 based on the read voltage difference ΔV. The current I flowing between the transparent conductive film 32 and the organic conductive film 42 is controlled in accordance with the flowchart shown in FIG. 8B together with the change in the area S of the pressing point shown in FIG. Change as shown.

  First, referring to FIGS. 8A and 8B, FIG. 8A shows the contact at the pressing point between the organic conductive film 42 and the transparent conductive film 32 as in FIG. 5A. FIG. 8B shows the change of the current I flowing between the organic conductive film 42 and the transparent conductive film 32 controlled by the flowchart of FIG.

In the present embodiment, the value of the current I supplied by the drive circuit 55 in the standby state of the coordinate input device 50 shown in step 1 of FIG. 7 is set to a very small initial value I _INIT , for example, 1 μA. For this reason, even in the initial state where the organic conductive film 52 and the transparent conductive film 32 are in contact with each other, the increase in the current I due to the transient phenomenon as described with reference to FIGS.

  Further, in this embodiment, in step 2 of FIG. 7, the CPU 54 monitors the voltage ΔV generated between the organic conductive film 42 and the transparent conductive film 32 via the A / D converter 56. Based on the change in the voltage ΔV, the contact between the organic conductive film 52 and the transparent conductive film 32 and the change in the contact area S are detected.

Referring again to FIG. 4, the voltage difference ΔV indicates that the contact resistance between the organic conductive film 42 and the transparent conductive film 32 is R, and the current flowing between the organic conductive film 42 and the transparent conductive film 32 is I. ΔV = RI, but the resistance R decreases in inverse proportion to the contact area S. Therefore, in the initial stage of contact, the voltage ΔV is proportional to (1 / S) × I _INIT (ΔV = RI∝ (1 / S) × I _INIT ).

Therefore, in the loop of step 2 and step 3 in FIG. 7, the CPU 54 monitors the detection of ΔV, and when the voltage ΔV is detected, determines that the organic conductive film 42 and the transparent conductive film 32 are in contact with each other. 4, the drive circuit 55 is controlled, and the value of the current I is gradually and continuously increased from the initial value I _INIT as shown in FIG. 8B.

Further, when the value of the current I reaches a predetermined maximum value I _MAX , for example, 100 μA, the CPU 54 controls the drive circuit 55 so that the maximum value I _MAX is maintained.

  Thereafter, the CPU 54 resets the drive circuit 55, returns to the step 1, and waits for the next pressing.

  In the control of FIG. 7, the current density J (= I / S) at the pressing point is constant as shown in FIG. 8C based on the value of the current I in step 4 and the voltage ΔV. It is also possible to control so that

More specifically, let A be a proportional coefficient,
ΔV = A × (1 / S) × I _INIT
Therefore, the contact area S is calculated using the voltage difference ΔV as follows: S = A × (1 / ΔV) × I _INIT
Therefore, the formula J = I / S = I / (A × (1 / ΔV) × I _INIT )
The value of the current I may be changed in accordance with the detected voltage difference ΔV so that the current density J given by

  By such control, the present invention can avoid the problem of damage to the organic conductive film 42 described above with reference to FIGS.

  FIG. 9 shows an example of the drive circuit 55 of FIG.

  Referring to FIG. 9, the drive circuit 55 includes push-pull-connected bipolar transistors Q1 and Q2 connected to a 5V power supply and supplying a drive current to the electrode 43A, and connected to a 5V power supply to the electrode 33A. Includes push-pull connected bipolar transistors Q3 and Q4 for supplying a driving current. Therefore, by supplying a control signal from the CPU 54 to the respective bases of the bipolar transistors Q1 to Q4 via an appropriate D / A converter (not shown), the drive circuit 55 causes the control signal to be supplied as shown in FIG. It is possible to perform the operation described in.

  In this embodiment, the case where the control of the drive circuit 55 is controlled using the CPU 54 and the flowchart of FIG. 7 has been described. However, the above configuration can also be realized by an analog circuit.

  In the coordinate input device 50 according to the present embodiment, the power supply voltage is not limited to 5V, and any power supply voltage in the range of 1 to 10V can be used. Further, the lower limit and the upper limit of the drive current I supplied by the drive circuit 55 are not limited to 1 μA and 100 μA, and other values are used as long as the problems shown in FIGS. 5A to 5C do not occur. It is also possible.

  In the coordinate input device 50 according to the present embodiment, the transparent organic conductive film 42 is made of thiophene, polyaniline, or polypyrrole represented by polyacetylene, polypyrrole, polythiophene, polyphenylenevinylene, and their derivative polymers. An organic conductive polymer can be used. On the other hand, in this embodiment, an inorganic transparent conductor such as ITO is used as the transparent conductive film 32 facing the transparent organic conductive film 42, but other inorganic transparent conductors such as ZnO can also be used. Further, the transparent conductive film 32 can be formed of an organic conductive polymer similar to the transparent organic conductive film 42.

  Further, by adding a fluorine-based additive to the transparent organic conductive film 42, it is possible to impart water repellency to the transparent organic conductive film 42 and improve moisture resistance.

  Here, as the fluorine-based additive to be added to the transparent organic conductive film 42, tetrafluoroethylene, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoropropylene copolymer Polymer, Tetrafluoroethylene / ethylene copolymer, Polyvinylidene fluoride, Polychlorotrifluoroethylene, Chlorotrifluoroethylene / ethylene copolymer, Fluorocarbon, Perfluorobutyl sulfonate, Perfluoroalkyl group-containing carboxylate, Per Fluororesin comprising one or more compounds selected from the group consisting of fluoroalkyl group-containing phosphates, and fluorinated diss containing perfluoroalkyl groups and hydrophilic and / or lipophilic groups And one or more compounds selected from the group consisting of silylating agent of any one of trifluoropropyltrichlorosilane and trifluoropropyltrimethoxysilane can be used alone or in combination. It is.

  Further, in the above, a silane coupling agent may be used in combination, and further, a low molecular weight epoxy resin or a low molecular weight acrylic resin may be used in combination.

  The method of forming the transparent organic conductive film 42 is not limited, but can be performed by a coating method using a die coater, a blade coater, a gravure coater, a dip coater, or the like.

  In addition to the polyethylene terephthalate resin, the transparent resin substrate 22 may be made of polycarbonate resin, norbornene resin, polysilicon methyl methacrylate resin, or glass.

  Further, as the transparent resin substrate 22, a resin having an ultraviolet blocking function can be used.

  Further, a dye soluble in the solvent of the transparent organic conductive film may be added to the transparent organic conductive film 42 as necessary.

  As mentioned above, although this invention was described about preferable embodiment, this invention is not limited to this specific embodiment, A various deformation | transformation and change are possible within the summary described in the claim.

It is a disassembled perspective view which shows the structure of the conventional coordinate input device. It is a figure explaining operation | movement of the coordinate input device of FIG. It is a figure explaining operation | movement of the coordinate input device of FIG. It is a figure which shows the mode of the contact of a resistive film in the coordinate input device of FIG. It is a figure explaining the problem of the coordinate input device of FIG. It is a figure which shows the structure of the coordinate input device by embodiment of this invention. It is a flowchart which shows the drive method of the coordinate input device of FIG. It is a figure which shows the mode of a drive of the coordinate input device of FIG. It is a figure which shows the structure of the drive circuit used with the coordinate input device of FIG.

Explanation of symbols

21 Glass substrate 22 Resin substrate 23 Spacer 32 Transparent conductive film 33A, 34A, 43A, 44A Electrode 33-38, 43, 44 Wiring pattern 40, 50 Coordinate input device 40P Stylus pen 42 Transparent organic conductive film 43S, 43T, 44S, 44T Terminal section 54 CPU
55 Drive circuit 56 A / D converter

Claims (5)

A first substrate carrying a first resistive film;
A second substrate carrying a second resistance film and disposed so as to face the first substrate with the second resistance film facing away from the first resistance film;
With
One of the first and second substrates is pressed at a pressing point, the portions corresponding to the pressing point in the first and second resistance films are brought into contact with each other, and the coordinates of the pressing point are read. In the coordinate input device,
The coordinate input device includes a drive circuit that supplies a current flowing between the first resistance film and the second resistance film,
The drive circuit determines the value of the current flowing between the first resistance film and the second resistance film at the pressing point, and the contact between the first resistance film and the second resistance film at the pressing point. A coordinate input device that continuously increases from a first value to a second value larger than the first value in accordance with an increase in area.   The coordinate input device according to claim 1, wherein the drive circuit detects a change in the contact area as a change in voltage between the first and second resistance films.   The coordinate input device according to claim 1, wherein the drive circuit controls the current value so that a current density value obtained by dividing the current value by the contact area is constant.   The coordinate input according to any one of claims 1 to 3, wherein the control circuit controls the current value to be constant after the current value reaches the second value. apparatus. A first substrate carrying a first resistive film;
A second substrate carrying a second resistance film and disposed so as to face the first substrate with the second resistance film facing away from the first resistance film;
With
One of the first and second substrates is pressed at a pressing point, the portions corresponding to the pressing point in the first and second resistance films are brought into contact with each other, and the coordinates of the pressing point are read. A driving method of a coordinate input device,
When the pressing point is pressed, the value of the current flowing between the first resistance film and the second resistance film at the pressing point is set to the value of the first resistance film and the second value at the pressing point. A driving method of a coordinate input device, wherein the first value is continuously increased from a first value to a second value larger than the first value in accordance with an increase in the contact area of the resistance film.

Images