JP2011210081A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detector that suppresses the increase of the number of circuits for processing signals from a piezoelectric body.SOLUTION: The position detector, which comprises a protective layer 5, a stripe electrode 6, a piezoelectric body 7, a single electrode 8, a cushion 9, a base 10, a multiplexer 11, and an operational amplifier circuit 12, detects a current generated in the piezoelectric body 7 via the stripe electrode 6 with a plurality of pads 13 connected thereto.

Description

  The present invention relates to a position detection device.

  In recent years, the use of touch panels as electronic blackboards, mobile phones, tablet PCs, digital signage, and other position detection devices has increased rapidly. Various methods such as a resistive film method, a capacitance method, an infrared method, and the like have been proposed as a touch panel method. One of them is a position detection device using a piezoelectric body (see, for example, Patent Document 1). This consists of a pressure-sensitive substrate on which a large number of piezoelectric bodies are arranged. The piezoelectric body has a characteristic of outputting a voltage according to mechanical pressure, and one metal wiring is connected to one piezoelectric body.

  A signal transmitted on the metal wiring connected to each piezoelectric body is input to an operational amplifier circuit and the like, and the output voltage is digitized. By analyzing the output voltage, the touched position and the mechanical pressure can be known. In order to improve the detection accuracy, the piezoelectric bodies must be arranged at a high density. However, since there is a limit to the routing of wiring in a single layer, in Patent Document 1, a high-density arrangement of piezoelectric bodies is realized by multilayering the layers for routing the wiring.

  Normally, signals transmitted on the metal wiring connected to each piezoelectric body are sequentially switched by a multiplexer (switch) or the like and input to an operational amplifier circuit or the like, and the output voltage is digitized. That is, the number of circuits is suppressed by time sharing one operational amplifier circuit with a plurality of piezoelectric bodies.

JP-A-01-121918

  However, the processing time required for one operational amplifier circuit is determined by the operation clock frequency used in the circuit and the delay speed of each element. When the number of piezoelectric bodies that share one operational amplifier circuit increases, the time interval for processing signals from one piezoelectric body becomes longer. In this case, even if the density of the piezoelectric body is increased, the detection accuracy is reduced. Therefore, the number of piezoelectric bodies that can share one operational amplifier circuit is limited. As a result, in the above-described conventional configuration, there is a problem that the operational amplifier circuits for processing these signals increase as the density of the piezoelectric bodies becomes higher.

  The present invention solves such a conventional problem, and an object of the present invention is to provide a position detection device that suppresses an increase in the number of circuits that process signals from a piezoelectric body.

  In order to achieve the above object, the present invention provides a pressure-sensitive layer made of a piezoelectric body, a first electrode layer formed on one surface of the pressure-sensitive layer made of a plurality of stripe electrodes having a connecting portion, And a second electrode layer formed on the other surface of the pressure-sensitive layer made of a single electrode. According to this configuration, even if any one of the stripe electrodes is touched, touch detection is performed without performing time sharing between the stripe electrodes.

  According to the position detection device of the present invention having the above configuration, even if any one of the stripe electrodes is touched, the touch detection is performed without performing time sharing between the stripe electrodes. The increase in the number of circuits for processing can be suppressed.

The perspective view which showed the usage example of the position detection apparatus in one Example of this invention. The perspective view which showed the structure of the position detection apparatus in one Example of this invention. FIG. 1 is an enlarged view of a stripe electrode of a position detection device according to an embodiment of the present invention. Sectional drawing of the position detection apparatus in one Example of this invention Sectional drawing of the position detection apparatus in one Example of this invention Output voltage waveform diagram in one embodiment of the present invention Output voltage waveform diagram in one embodiment of the present invention Output voltage waveform diagram in one embodiment of the present invention Output voltage waveform diagram in one embodiment of the present invention The flowchart in one Example of this invention The flowchart in one Example of this invention

  Hereinafter, specific contents of the present invention will be described with reference to examples.

  FIG. 1 to FIG. 5 are diagrams showing an example of the usage situation and structure of the position detection device.

  In FIG. 1, 1 is an electronic blackboard, 2 is a position detection device, and the front surface of the electronic blackboard 1 is a position detection device 2. 3 is a projector and 4 is a notebook computer. The screen information of the notebook computer 4 is projected onto the position detection device 2 by the projector 3. By looking at the projected information and pressing the position detection device 2 with a finger or a dedicated pen, characters and graphic information are added to, deleted from, and operated on the icon. The electronic blackboard 1 is an example, and includes products that can incorporate a position detection device, such as a digital signage device, a portable terminal, and a laptop computer.

  FIG. 2 is a diagram illustrating a basic structure and a basic circuit of the position detection device 2. 5 is a protective layer, 6 is a striped electrode in which a plurality of pads are connected, 7 is a piezoelectric body, 8 is a single electrode, 9 is a cushion, 10 is a base material, 11 is a multiplexer for switching, 12 is an input coordinate And an operational amplifier circuit for obtaining the pressing force. When the surface of the protective layer 5 is pressed with a finger, a voltage is generated in the piezoelectric body 7, and the voltage passes through the stripe electrode 6, passes through the multiplexer 11, and is digitized by the operational amplifier circuit 12. Suitable materials for the stripe electrode 6 and the single electrode 8 are metal, transparent ITO, and organic conductive film.

  FIG. 3 is a partially enlarged view of the stripe electrode 6. Reference numeral 13 denotes a pad, and reference numeral 14 denotes a connecting portion, which is formed of a conductor. The line width of the connecting portion 14 is preferably 0.1 mm to 0.5 mm. The pads 13 are connected by a connecting portion 14. The shape of the pad 13 is an example, and may be, for example, a circle, a triangle, or a polygon. The position detection resolution of the position detection device 2 becomes higher as the area of the pad 13 is smaller and the patterns are integrated.

  FIG. 4 is a cross-sectional view of the position detection device 2. 5 is a protective layer, 6 is a stripe electrode, 7 is a piezoelectric body, 8 is a single electrode, 9 is a cushion, and 10 is a substrate. Each layer may be bonded to all layers or only a part of the layers.

  FIG. 5 is a cross-sectional view of the position detection device 2. When the position detection device 2 is pressed with a finger, the protective layer 5, the stripe electrode 6, the piezoelectric body 7, the single electrode 8, and the cushion 9 are deformed. At this time, the piezoelectric body 7 is deformed, and a voltage is generated between the stripe electrode 6 and the single electrode 8. It has been confirmed that the cushion 9 generates a high voltage by using a material having a small hardness and a large repulsive force, such as silicon or urethane. The thickness of the cushion 9 is desirably 0.5 mm to 2 mm. The cushion 9 is not limited to a single material of silicon or urethane, and may be a laminate of two or more types of cushion materials.

  FIG. 6 is a basic circuit diagram of the position detection device 2. The left and right resistors R1 and R2 at the point P indicate the resistance of the stripe electrode 6, and the point P indicates a point pressed by a finger or a dedicated pen. The resistors R1 and R2 are connected to a multiplexer 11 for performing high-speed switching. The multiplexer 11 is connected to the operational amplifier circuit 12 and acquires input coordinates (X, Y) and pressing force data. The output voltage waveform 15 output when pressed will be described. When the stripe electrode 6 of FIG. 3 is pressed with the finger on the left side from the center in the X direction, R1 <R2. At this time, the voltage peak value output from the position detection device 2 is V1> V2, and the X coordinate can be known from this voltage ratio.

  FIG. 7 is a diagram illustrating the output voltage waveform 15 when a gesture input in the horizontal direction is performed. 7 shows the output voltage V1 from the CH2L of the stripe electrode 6 and the output waveform 15 on the right of FIG. 7 shows the output voltage V2 from the CH2R of the stripe electrode 6. When the finger is moved in the right direction from the CH2L side between the CH2L and CH2R of the stripe electrode 6, the output voltage waveform 15 is output as V1 and V2 in FIG. By comparing the output voltages of V1 and V2 corresponding to this time change, it is possible to know the X coordinate, the Y coordinate based on the multiplexer CH position, and the pressing force based on the voltage level.

  FIG. 8 is a diagram illustrating the output voltage waveform 15 when a gesture input in the vertical direction is performed. In this case, the voltage from CH1L to CH5L of the stripe electrode 6 is output as indicated by V1, and the voltage from CH1R to CH5R of the stripe electrode 6 is output as indicated by V2. Therefore, when the finger is moved in the vertical direction from CH1 to CH5 between CH1 and CH5 of the stripe electrode 6, the output voltage waveform 15 is output as V1 and V2, and therefore this time change is supported. By comparing the output voltages of V1 and V2, the pressing force can be known from the X coordinate, the Y coordinate from the multiplexer CH position, and the magnitude of the voltage.

  FIG. 9 is a diagram illustrating the output voltage waveform 15 when a diagonal gesture input is performed. In this case, the voltage of CH1L to CH5L of the stripe electrode 6 is output as shown in the V1 graph, and the voltage of CH5R to CH5R of the stripe electrode 6 is output as shown in V2. Therefore, when the finger is moved in the oblique direction between CH1 and CH5 between the CH1 and CH5 of the stripe electrode 6, the output voltage waveform 15 is output as V1 and V2, and therefore this time change is supported. By comparing the output voltages of V1 and V2, the pressing force can be known from the X coordinate, the Y coordinate from the multiplexer CH position, and the magnitude of the voltage.

  FIG. 10 is an example of a flowchart for detecting a gesture input to the position detection device 2. The standard input mode is a case where dedicated pen input is performed on the position detection device 2 of the electronic blackboard 1.

  When it is confirmed whether the touch is made (S101), the voltage by the multiplexer is detected (S102), the input coordinates (X, Y) are acquired, and the pressing force is acquired (S103). Next, pattern discrimination is performed (S104). Finally, the pattern is projected on the screen of the position detection device 2 by the projector 3 (S105).

  FIG. 11 is a flowchart describing details of the pattern discrimination (S104) of FIG. When the output voltage from the multiplexer is CH (n) L> 0, CH (n) R> 0 (S201), and the next output voltage is CH (n) L> 0, CH (n) R> 0 (S202). ), The input pattern is horizontal input (S206). At this time, if CH (n) L = 0, CH (n) R = 0 and CH (n + 1) L> 0, CH (n + 1) R> 0, the input pattern is an oblique input (S207). Further, CH (n) L = 0, CH (n) R = 0, CH (n + 1) L = 0, CH (n + 1) R = 0, CH (n + 2) L> 0, and CH (n + 2) R> 0. If there is, the input pattern is a vertical direction input (S208). If all branches from S202 to S204 are “NO”, the input pattern is a point input (S205).

  As described above, according to the first embodiment, even if any of the plurality of pads 13 on one stripe electrode is touched by the above configuration, time sharing is performed between the plurality of pads 13. Since the touch is detected without increasing, the increase in the number of circuits for processing the signal from the piezoelectric body can be suppressed.

  Since the position detection device according to the present invention can process signals from a plurality of pads without time sharing, an increase in the number of circuits for processing signals from a piezoelectric body can be suppressed. It can be used for electronic blackboards, digital signage devices, mobile terminals, laptop computers, and so on.

DESCRIPTION OF SYMBOLS 1 Electronic blackboard 2 Position detection apparatus 3 Projector 4 Notebook computer 5 Protective layer 6 Stripe electrode 7 Piezoelectric body 8 Single electrode 9 Cushion 10 Base material 11 Multiplexer 12 Operational amplifier circuit 13 Pad 14 Connection part 15 Output voltage waveform

Claims (5)

A pressure-sensitive layer made of a piezoelectric material; a first electrode layer formed on one surface of the pressure-sensitive layer made of a plurality of stripe electrodes having connecting portions; and the other of the pressure-sensitive layer made of a single electrode And a second electrode layer formed on the surface. The position detection device according to claim 1, wherein the plurality of stripe electrodes are arranged in a staggered manner. The position detection device according to claim 1, further comprising a protective layer on a surface layer of either the first electrode layer or the second electrode layer. The position detection apparatus according to claim 1, further comprising: a cushion on a surface layer of either the first electrode layer or the second electrode layer, and a base material on a non-contact surface with the electrode of the cushion. The position detection device according to claim 1, wherein a position pressed by a finger or a dedicated pen is specified by detecting a potential difference between both ends of the stripe electrode.

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