JP6945354B2 - Force detector - Google Patents

Description

The present invention relates to a force detecting device having a sensor layer made of a pressure sensitive material.

There is known a pressure detection device in which small pressure sensor elements are arranged in a two-dimensional array to enable measurement of a pressure distribution (see, for example, Non-Patent Document 1 and Patent Document 1). In such a pressure detection device, the pressure sensor element outputs a signal voltage corresponding to the pressure applied from the outside. Further, in many cases, it is assumed that the pressure detection device uses a thin film transistor (TFT) to actively matrix control the pressure sensor element as in the case of driving a pixel in an image display panel (for example,). See Patent Document 1).

In the active matrix type two-dimensional pressure sensor, for example, two-dimensional pressure distribution data is acquired by sequentially changing the pressure sensor element that switches the active gate wiring and reads out using a shift register. By constantly continuing this operation, it is possible to acquire two-dimensional data of the pressure that changes with time.

On the other hand, as a sensor device for measuring contact pressure and shear force, a sensor device having a 4-gauge method bridge circuit including a contact pressure measuring unit and a shearing force measuring unit is known (see Patent Document 2). In the sensor device described in Patent Document 2, the shear force measuring unit aligns and faces the comb portion of the comb-shaped electrode on the one-sided electrode and the comb-shaped electrode on the facing-side electrode, and a pressure conversion element between the two electrodes. It is configured by sandwiching.

Further, a technique of measuring pressure by a strain sensor using an optical fiber Bragg grating is known (see Patent Document 3). Further, a technique for measuring shear force and pressure by using an X-axis sensor, a Y-axis sensor and a Z-axis sensor composed of a piezo resistance cantilever in combination is known (see Patent Document 4).

Japanese Unexamined Patent Publication No. 10-0707278 Japanese Patent No. 5688792 JP-A-2007-263937 Japanese Patent No. 5561674

NanotechJapan Bulletin Vol.6, No.3, 2013, pp.6-7

The two-dimensional pressure sensor as described above is expected to be applied as a sensor for detecting tactile information or the like at the fingertips of a robot imitating a human being, for example. However, in the conventional two-dimensional pressure sensor, among the forces acting on the sensor surface which is the contact surface on which the force acts, the pressure which is the force perpendicular to the sensor surface can be detected, but is parallel to the sensor surface. Could not detect the force.

For example, when an object in contact with the sensor surface is pulled sideways or slid, a force parallel to the sensor surface such as a shearing force or a frictional force acts on the sensor surface. With a conventional two-dimensional pressure sensor, it is not possible to detect a force parallel to the sensor surface. Therefore, even if a tactile sensor is constructed using a conventional two-dimensional pressure sensor, it is considered difficult to detect an action of pulling or sliding an object in contact with the sensor surface.

Information on the direction and magnitude of a force parallel to a contact surface such as a shearing force is important information in, for example, a situation where a robot fingertip grips an object. For example, when the object gripped by the fingertip of the robot is about to shift, if the direction of the shift is known to be the direction of gravity or the opposite direction, or the direction orthogonal to the direction of gravity, the gripping force is strengthened or weakened. It can be determined and controlled whether it is maintained or maintained.

On the other hand, in the sensor device described in Patent Document 1, it is considered that it is not always easy to accurately align the positions of the two layers of comb-shaped electrodes facing each other. On the other hand, a device that uses an optical fiber as a sensor device as in the technique described in Patent Document 3 is considered to be unsuitable for miniaturization of the device. Further, a technique using a sensor corresponding to three orthogonal axes of an X-axis sensor, a Y-axis sensor, and a Z-axis sensor, such as the technique described in Patent Document 4, is considered to have a complicated configuration and a high manufacturing cost. ..

An object of the present invention is to provide a force detecting device capable of detecting a force parallel to a sensor surface acting on the sensor surface without requiring a complicated configuration.

According to one aspect of the present invention, a force sensor having three or more electrodes, a sensor layer formed on the three or more electrodes and made of a pressure-sensitive material, and the three or more of the force sensors. Provided is a force detecting device comprising a detecting unit for detecting an electric resistance value between two or more sets of electrodes among the electrodes.

According to the present invention, it is possible to detect a force parallel to the sensor surface acting on the sensor surface without requiring a complicated configuration.

FIG. 1 is a schematic view showing the overall structure of the force detecting device according to the first embodiment of the present invention. FIG. 2 is a plan view showing the structure of a cell array including a sensor cell in the force detection device according to the first embodiment of the present invention. FIG. 3 is a plan view illustrating the electric resistance value of the sensor cell in the force detection device according to the first embodiment of the present invention. FIG. 4 is a diagram showing a correspondence relationship between the magnitude relation of each electric resistance value of the sensor cell and the direction of the force in the force detection device according to the first embodiment of the present invention. FIG. 5 is a plan view showing the structure of a cell array including a sensor cell in the force detection device according to the second embodiment of the present invention. FIG. 6 is a plan view showing the structure of a cell array including a sensor cell of a two-dimensional pressure sensor according to the background technology. FIG. 7 is a plan view for explaining the electric resistance value of the sensor cell of the two-dimensional pressure sensor according to the background technology.

[First Embodiment]
The force detection device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic view showing the overall structure of the force detecting device according to the present embodiment. FIG. 2 is a plan view showing the structure of a cell array including a sensor cell in the force detection device according to the present embodiment. FIG. 3 is a plan view for explaining the electric resistance value of the sensor cell in the force detection device according to the present embodiment. FIG. 4 is a diagram showing a correspondence relationship between the magnitude relation of each electric resistance value of the sensor cell in the force detection device according to the present embodiment and the direction of the force.

The force detection device according to the present embodiment is, for example, a force parallel to the sensor surface that is incorporated in a touch panel of a liquid crystal display device, an OLED (Organic Light Emitting Diode) display device, or the like, or a finger of a robot and acts on the sensor surface. Is to be detected.

As shown in FIGS. 1 and 2, the force detection device 100 according to the present embodiment includes a sensor array 10, a gate line drive circuit 20, a detection circuit 30, a power supply line drive circuit 40, and a control unit 50. doing.

The sensor array 10 includes a plurality of sensor cells 60 arranged two-dimensionally over a plurality of rows (for example, m rows) and a plurality of columns (for example, n columns). Note that m and n are integers of 2 or more, respectively. In the sensor array 10, the plurality of sensor cells 60 are arranged in a rectangular grid such as a square grid.

Each sensor cell 60 includes two selection transistors M1 and M2, which are a first active element and a second active element, respectively, and a force sensor S using a pressure-sensitive material. The selection transistors M1 and M2 are made of, for example, thin film transistors, respectively. The force detection device 100 according to the present embodiment is an active matrix drive type sensor device using the selection transistors M1 and M2 as active elements.

The force sensor S has four electrodes 62A, 62B, 62C, 62D and a sensor layer 64 made of a pressure-sensitive material formed on the four electrodes 62A, 62B, 62C, 62D.

The electrodes 62A, 62B, 62C, and 62D constitute a first electrode, a second electrode, a third electrode, and a fourth electrode that are independent of each other. The electrodes 62A, 62B, 62C, and 62D are each formed on the substrate via an insulating layer. The sensor layer 64 is formed on an insulating layer having openings 66A, 66B, 66C, 66D that expose the electrodes 62A, 62B, 62C, and 62D, respectively, and is formed through the openings 66A, 66B, 66C, and 66D. Are in contact with the electrodes 62A, 62B, 62C, 62D. The substrate includes not only a substrate-like member but also a sheet-like member and a film-like member, and any material can be adopted as the material thereof. Further, the substrate may be a flexible one having flexibility or a hard one having no flexibility.

The sensor layer 64 is made of, for example, a pressure-sensitive material whose electric resistance value changes with a change in pressure. More specifically, examples of the pressure-sensitive material constituting the sensor layer 64 include a pressure-sensitive conductive material containing an insulating resin and a conductive filler dispersed in the insulating resin. In such a pressure-sensitive conductive material, the number of contacts of the conductive filler changes according to the magnitude of the applied pressure, so that the electric resistance value changes according to the magnitude of the applied pressure. Further, as the pressure-sensitive material constituting the sensor layer 64, it is also possible to use a pressure-sensitive conductive material in which fine irregularities are formed on the contact surface with the electrode with respect to the electrode in which fine irregularities are formed. In such a pressure-sensitive conductive material, the contact area with the electrode changes due to fine irregularities according to the magnitude of the applied pressure, so that the electric resistance value changes according to the magnitude of the applied pressure.

The sensor layer 64 has, for example, a substantially rectangular planar shape having two sets of sides along the row direction and the column direction. The planar shape of the sensor layer 64 is not particularly limited, and various shapes can be adopted.

On the other hand, the electrodes 62A, 62B, 62C, and 62D have the same planar shape as each other and have a planar shape smaller than that of the sensor layer 64. The electrodes 62A, 62B, 62C, 62D have, for example, a substantially rectangular planar shape having two sets of sides along the row direction and the column direction. The planar shapes of the electrodes 62A, 62B, 62C, and 62D are not particularly limited, and various shapes can be adopted.

The electrodes 62A, 62B, 62C, and 62D are two-dimensionally arranged at equal intervals.

The electrodes 62A, 62B, 62C, and 62D are arranged so as to be located at the four corners of the sensor layer 64. FIG. 2 shows a case where the electrodes 62A, 62B, 62C, and 62D are arranged in the upper left corner of the paper surface, the upper right corner of the paper surface, the lower left corner of the paper surface, and the lower right corner of the paper surface, respectively.

In this way, the surface on the side where the sensor layer 64 is formed on the electrodes 62A, 62B, 62C, and 62D is the sensor surface 70, which is a force detecting surface for detecting the force acting by the contacted object. A plurality of sensor layers 64 may be exposed on the sensor surface 70, or a protective layer (not shown) made of a resin material or the like that protects the sensor surface 70 including the plurality of sensor layers 64 is formed. May be good.

Each row of the sensor array 10 extends in the row direction and is a plurality of first gate lines GL1a, GL2a, ..., GLma, which are first drive signal lines for driving the selection transistor M1 which is the first active element. Are arranged. Further, in each row of the sensor array 10, a plurality of second gate lines GL1b, GL2b, ... , GLmb is arranged. The second gate lines GL1b, GL2b, ..., And GLmb are arranged corresponding to the first gate lines GL1a, GL2a, ..., GLma, respectively. The first gate lines GL1a, GL2a, ..., GLma, and the second gate lines GL1b, GL2b, ..., GLmb are connected to the gate line drive circuit 20. In the following, the first gate line will be appropriately referred to as "first gate line Glia", and the second gate line will be appropriately referred to as "second gate line GLib". However, i is an integer that satisfies 1 ≦ i ≦ m.

Data lines DL1, DL2, ..., DLn, which are output signal lines, are arranged in each row of the sensor array 10 extending in the row direction. The data lines DL1, DL2, ..., DLn are each connected to one end of the resistor R included in the detection circuit 30. The other end of the resistor R is connected to the ground voltage line of the ground voltage VS. The input terminal side of the A / D converter 68 included in the detection circuit 30 is connected to the connection node between the data lines DL1, DL2, ..., DLn and one end of the resistor R. The configuration for connecting the data lines DL1, DL2, ..., DLn to the A / D converter is not limited to the configuration shown in FIG. 2, and various configurations can be adopted. For example, a configuration can be adopted in which the data lines DL1, DL2, ..., DLn are connected to the input of a single A / D converter via a multiplexer. In the following, the data line will be appropriately referred to as “data line DLj”. However, j is an integer satisfying 1 ≦ j ≦ n.

Further, in each row of the sensor array 10, first power supply lines VL1a, VL2a, ..., VLna are arranged so as to extend in the row direction. Further, in each row of the sensor array 10, second power supply lines VL1b, VL2b, ..., VLnb are arranged so as to extend in the row direction and correspond to the first power supply lines VL1a, VL2a, ..., VLna. There is. The first power supply lines VL1a, VL2a, ..., VLna, and the second power supply lines VL1b, VL2b, ..., VLnb are connected to the power supply line drive circuit 40. In the following, the first power supply line will be appropriately referred to as "first power supply line VLja", and the second power supply line will be appropriately referred to as "second power supply line VLjb". However, j is an integer satisfying 1 ≦ j ≦ n.

The electrodes 62A, 62B, 62C, 62D and the selection transistors M1 and M2 of the force sensor S in the sensor cell 60 located in the i-th row and the j-th column are connected as follows.

That is, the gate electrode of the selection transistor M1 is connected to the corresponding first gate line Glia in the i-th row. The source electrode of the selection transistor M1 is connected to the corresponding data line DLj in the jth column. The drain electrode of the selection transistor M1 is connected to the electrode 62A.

Further, the gate electrode of the selection transistor M2 is connected to the second gate line GLib of the corresponding row i. The source electrode of the selection transistor M2 is connected to the corresponding data line DLj in the jth column. The drain electrode of the selection transistor M2 is connected to the electrode 62D.

Further, the electrode 62C is connected to the corresponding first power supply line VLja in the jth row. The electrode 62B is connected to the corresponding second power line VLjb in the jth row.

The gate line drive circuit 20 is composed of a decoder and a shift register. The gate line drive circuit 20 supplies the drive signal Pia to the first gate line Glia. Further, the gate line drive circuit 20 supplies a drive signal Pib to the second gate line GLib. The drive signal Pia is a drive signal of the selection transistor M1 connected to the first gate line Glia. Further, the drive signal Pib is a drive signal of the selection transistor M2 connected to the second gate line GLib. As described above, the gate line drive circuit 20 is a drive circuit for driving the selection transistors M1 and M2. For example, when the selection transistors M1 and M2 are N-type transistors, when the drive signals Pia and Pib are at a high level, the corresponding selection transistors M1 and M2 in the i-th row are turned on. Further, when the drive signals Pia and Pib are at a low level, the corresponding selection transistors M1 and M2 in the i-th row are turned off.

The detection circuit 30 is a circuit that detects the voltage of the data line DLj and functions as a detection unit for detecting the output of the electric resistance value between the electrodes in the force sensor S as described later, and is a resistor as described above. It includes R, A / D converter 68 and the like. Based on the output of the electric resistance value between the electrodes in the force sensor S detected by the detection circuit 30, it is possible to obtain the direction and magnitude of the force detected by the force sensor S.

The power supply line drive circuit 40 supplies the power supply voltage VD to the first power supply line VLja to turn on the first power supply line VLja, and sets the first power supply line VLja to a high impedance to turn it off. Further, the power supply line drive circuit 40 supplies the power supply voltage VD to the second power supply line VLjb to turn on the second power supply line VLjb, and sets the second power supply line VLjb to a high impedance to turn it off.

The control unit 50 is connected to the gate line drive circuit 20, the detection circuit 30, and the power supply line drive circuit 40. The control unit 50 has a CPU (Central Processing Unit) that executes processing such as various calculations, controls, and determinations. Further, the control unit 50 has a ROM (Read Only Memory) for storing various programs executed by the CPU, a database referenced by the CPU, and the like. Further, the control unit 50 has a RAM (Random Access Memory) for temporarily storing data being processed by the CPU, input data, and the like. The control unit 50 may be integrally built in the force detection device 100, or its function may be realized by a separate and independent computer device.

The control unit 50 controls the operation and timing of the gate line drive circuit 20, the detection circuit 30, and the power supply line drive circuit 40 via a control circuit (not shown) or the like by the CPU executing a program. Further, the control unit 50 determines the direction and magnitude of the force applied to the sensor surface of the force detection device 100 based on the output of the electric resistance value of the force sensor S detected by the detection circuit 30 when the CPU executes the program. Functions as a processing unit for obtaining.

An object may come into contact with the sensor surface 70 of the force detection device 100, and a force parallel to the sensor surface 70 may act on the sensor surface 70. The force parallel to the sensor surface 70 acting on the sensor surface 70 includes a component of the force acting in the direction inclined with respect to the sensor surface 70, which is parallel to the sensor surface 70. Specifically, the force parallel to the sensor surface 70 acting on the sensor surface 70 includes, for example, a shearing force, a frictional force, and the like.

When a force parallel to the sensor surface 70 acts in this way, in the force sensor S having a plurality of electrodes 62A, 62B, 62C, 62D in contact with the common sensor layer 64, depending on the direction of the force parallel to the sensor surface 70. A distribution can occur in the pressure acting on the sensor layer 64. Therefore, there may be a relative magnitude relationship between the electrical resistance values between the plurality of electrodes 62A, 62B, 62C, and 62D. The magnitude relationship of the electric resistance value in the force sensor S can be associated with the direction of the force parallel to the sensor surface 70. Further, the magnitude of the force parallel to the sensor surface 70 can be obtained based on the electric resistance value between the electrodes 62A, 62B, 62C, and 62D.

As shown in FIG. 3, in the force sensor S, the electric resistance value R _{AB between the electrode 62A and the electrode 62B, the electric resistance value R AC} between the electrode 62A and the electrode 62C, and between the electrode 62B and the electrode 62D. electric resistance between the electric resistance value _{R BD} and electrode 62C and the electrode 62D of _{R CD} are defined. The values of these electric resistance values R _AB , R _AC , R _BD , and R _CD have a relative magnitude relationship depending on the direction of the force parallel to the sensor surface 70.

When a force parallel to the sensor surface 70 acts on the sensor surface 70 parallel to the paper surface of the force sensor S shown in FIG. 3, the relative magnitudes of the _{electrical resistance values R AB} , _RAC , R _BD , and R _CD The relationship is as shown in FIG. The symbol "~" indicates that the electric resistance values on both sides are almost equal.

That is, when a force acting perpendicularly from the top to the bottom of the paper surface acts on the sensor surface 70, the relative magnitude relationship of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD is R CD} <R _AC. ~ R _BD <R _AB .

When a force acting perpendicularly from the bottom to the top of the paper surface acts on the sensor surface 70, the relative magnitude relationship of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD is R AB} <R _AC. ~ R _BD <R _CD .

When a force acting parallel to the sensor surface 70 from the left to the right of the paper surface acts, the relative magnitude relationship of the _{electrical resistance values R AB} , _RAC , R _BD , and R _{CD is R BD} <R _AB. the ~R _{CD <R AC.}

When a force acting parallel to the sensor surface 70 from the right to the left of the paper surface acts, the relative magnitude relationship of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD is R AC} <R _AB. ~ R _CD <R _BD .

When a force acting from the upper left to the lower right of the paper surface at an angle of 45 ° acts on the sensor surface 70, the relative magnitude relationship of the _{electrical resistance values R AB} , _RAC , R _BD , and R _{CD is R BD.} ~ R _CD <R _AB ~ R _AC .

When a force acting from the lower right to the upper left of the paper surface at an angle of 45 ° acts on the sensor surface 70, the relative magnitude relationship of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD is R AB.} ~ R _AC <R _BD ~ R _CD .

When a force acting from the upper right to the lower left of the paper surface at an angle of 45 ° acts on the sensor surface 70, the relative magnitude relations of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD are R AC} ~. R _CD <R _{AB to} R _BD .

When a force acting from the lower left to the upper right of the paper surface at an angle of 45 ° acts on the sensor surface 70, the relative magnitude relationship of the _{electrical resistance values R AB} , R _AC , R _BD , and R _{CD is R AB} ~. R _BD <R _AC ~ R _CD .

In this way, the direction of the force parallel to the sensor surface 70 can be obtained based on the electric resistance value between the electrodes 62A, 62B, 62C, and 62D in each force sensor S, and further, the force parallel to the sensor surface 70 can be obtained. The size of can also be obtained. Since the relative magnitude relationship between the electrical resistance values between the electrodes differs depending on the pressure-sensitive material constituting the sensor layer 64 and the structure and shape of the sensor layer 64, it can be obtained in advance by experiments or simulations. ..

The force detecting device 100 according to the present embodiment _{can acquire the electric resistance values R AB} , R _AC , R _BD , and R _CD as follows, and can acquire the relative magnitude relationship between them. Hereinafter, the operation sequence of the force detecting device 100 according to the present embodiment will be described.

An object is in contact with the sensor surface 70 of the force detection device 100 according to the present embodiment, and a force parallel to the sensor surface 70 acts on the sensor surface 70.

First, the drive signal Pia is supplied from the gate line drive circuit 20 to the first gate line Glia in the i-th row, and the first gate line Glia in the i-th row is turned on. As a result, the selection transistor M1 connected to the first gate line Glia in the i-th row is turned on on a row-by-row basis. On the other hand, the other first gate line and the second gate line are in the off state in which the drive signal is not supplied.

As described above, the first gate line Glia of the i-th row is turned on, and the power supply line drive circuit 40 supplies the power supply voltage VD to the first power supply lines VL1a, VL2a, ..., VLna to supply the first power supply. The lines VL1a, VL2a, ..., VLna are turned on. On the other hand, the power supply line drive circuit 40 sets the second power supply lines VL1b, VL2b, ..., VLnb as high impedance and turns off the second power supply lines VL1b, VL2b, ..., VLnb.

As described above, the first gate line GLia of the i-th row is turned on, the other first gate line and the second gate line are turned off, the first power supply lines VL1a, VL2a, ..., VLna are turned on, and the first 2 Turn off the power lines VL1b, VL2b, ..., VLnb. Thus, the data lines DL1, DL2, ......, the DLn, a voltage corresponding to the electric resistance value _{R AC} between the electrode 62A and the electrode 62C of the force sensor S at the corresponding sensor cell 60 of the i-th row respectively output Will be done. Detection circuit 30, the data lines DL1, DL2, ......, voltage detecting in accordance with the electric resistance value _{R AC} output to DLn. Thus, the detection circuit 30 which functions as a detection unit for each sensor cell 60 of the i-th row, it is possible to detect the electric resistance value R _AC.

Next, the on / off state of the first power supply line and the second power supply line is switched while maintaining the on state of the first gate line Glia in the i-th row and the off state of the other first gate line and the second gate line. That is, the power supply line drive circuit 40 sets the first power supply lines VL1a, VL2a, ..., VLna as high impedance, and turns off the first power supply lines VL1a, VL2a, ..., VLna. On the other hand, the power supply line drive circuit 40 supplies the power supply voltage VD to the second power supply lines VL1b, VL2b, ..., VLnb to turn on the second power supply lines VL1b, VL2b, ..., VLnb.

As described above, the first gate line GLia of the i-th row is turned on, the other first gate line and the second gate line are turned off, the first power supply lines VL1a, VL2a, ..., VLna are turned off, the first 2 Turn on the power supply lines VL1b, VL2b, ..., VLnb. Thus, the data lines DL1, DL2, ......, the DLn, a voltage corresponding to the electric resistance value _{R AB} between the electrodes 62A and the electrode 62B of the force sensor S at the corresponding sensor cell 60 of the i-th row respectively output Will be done. Detection circuit 30, the data lines DL1, DL2, ......, detecting a voltage corresponding to the electric resistance value _{R AB} output to DLn. Thus, the detection circuit 30 which functions as a detection unit for each sensor cell 60 of the i-th row, it is possible to detect the electric resistance value R _AB.

Next, the drive signal Pib is supplied from the gate line drive circuit 20 to the second gate line GLib of the i-th row, and the second gate line GLib of the i-th row is turned on. As a result, the selection transistor M2 connected to the second gate line GLib of the i-th row is turned on in row units. On the other hand, the other first gate line and the second gate line are in the off state in which the drive signal is not supplied.

As described above, the second gate line GLib of the i-th row is turned on, and the power supply line drive circuit 40 supplies the power supply voltage VD to the first power supply lines VL1a, VL2a, ..., VLna to supply the first power supply. The lines VL1a, VL2a, ..., VLna are turned on. On the other hand, the power supply line drive circuit 40 sets the second power supply lines VL1b, VL2b, ..., VLnb as high impedance and turns off the second power supply lines VL1b, VL2b, ..., VLnb.

As described above, the second gate line GLib of the i-th row is turned on, the other first gate line and the second gate line are turned off, the first power supply lines VL1a, VL2a, ..., VLna are turned on, and the second 2 Turn off the power lines VL1b, VL2b, ..., VLnb. Thus, the data lines DL1, DL2, ......, the DLn, a voltage corresponding to the electric resistance value _{R CD} between the electrode 62C and the electrode 62D of the force sensor S at the corresponding sensor cell 60 of the i-th row respectively output Will be done. Detection circuit 30, the data lines DL1, DL2, ......, detecting a voltage corresponding to the electric resistance value _{R CD} output to DLn. Thus, the detection circuit 30 which functions as a detection unit for each sensor cell 60 of the i-th row, it is possible to detect the electric resistance value R _CD.

Next, the on / off state of the first power supply line and the second power supply line is switched while maintaining the on state of the second gate line GLib of the i-th row and the off state of the other first gate line and the second gate line. That is, the power supply line drive circuit 40 sets the first power supply lines VL1a, VL2a, ..., VLna as high impedance, and turns off the first power supply lines VL1a, VL2a, ..., VLna. On the other hand, the power supply line drive circuit 40 supplies the power supply voltage VD to the second power supply lines VL1b, VL2b, ..., VLnb to turn on the second power supply lines VL1b, VL2b, ..., VLnb.

As described above, the second gate line GLib of the i-th row is turned on, the other first gate line and the second gate line are turned off, the first power supply lines VL1a, VL2a, ..., VLna are turned off, and so on. 2 Turn on the power supply lines VL1b, VL2b, ..., VLnb. Thus, the data lines DL1, DL2, ......, the DLn, a voltage corresponding to the electric resistance value _{R BD} between the electrode 62B and the electrode 62D of the force sensor S at the corresponding sensor cell 60 of the i-th row respectively output Will be done. Detection circuit 30, the data lines DL1, DL2, ......, detecting a voltage corresponding to the electric resistance value _{R BD} output to DLn. Thus, the detection circuit 30 which functions as a detection unit for each sensor cell 60 of the i-th row, it is possible to detect the electric resistance value R _BD.

By sequentially performing the above-mentioned operations for the first row to the mth row, the detection circuit 30 that functions as a detection unit for each sensor cell 60 in the sensor array 10 has electrical resistance values R _AB , _RAC , R _BD , and R _CD. Are individually detected and acquired. For each sensor cell 60, the control unit 50 determines the direction and magnitude of the force parallel to the sensor surface 70 acting on the sensor surface 70 based _{on the acquired electrical resistance values R AB} , _RAC , R _BD , and R _CD. Ask for. That is, the control unit 50 acts on the sensor surface 70 that acts on the sensor surface 70 based on the relative magnitude relationship _{of the acquired electrical resistance values R AB} , _RAC , R _BD , and R _{CD for each sensor cell 60.} Find the direction of parallel forces. Further, the control unit 50 determines the magnitude of the force parallel to the sensor surface 70 acting on the sensor surface 70 based _{on the acquired electrical resistance values R AB} , _RAC , R _BD , and R _{CD for each sensor cell 60.} Ask for.

For example, the control unit 50 _{relates to the relationship between the relative magnitude relationship of the electric resistance values R AB} , _RAC , R _BD , and R _CD and the direction of the force parallel to the sensor surface 70 acting on the sensor surface 70. The database is held in storage. With reference to such a database, the control unit 50 can determine the direction of the force parallel to the sensor surface 70 acting on the sensor surface 70 for each sensor cell 60.

Further, the control unit 50 _{holds a database in the storage device regarding the relationship between the electric resistance values R AB} , _RAC , R _BD , and R _CD and the magnitude of the force parallel to the sensor surface 70 acting on the sensor surface 70. doing. The control unit 50 can also obtain the magnitude of the force parallel to the sensor surface 70 acting on the sensor surface 70 for each sensor cell 60 with reference to such a database.

Further, the control unit 50 can perform statistical processing on a plurality of nearby sensor cells 60 by using the detection results of the direction and magnitude of the force parallel to the sensor surface 70 acting on the sensor surface 70. .. As a result, it is possible to reduce an error in the detection result of the force parallel to the sensor surface 70 acting on the sensor surface 70. For example, for a plurality of sensor cells 60 such as 2 × 2, 3 × 3 in the row direction and the column direction, the detection results of the force direction and magnitude parallel to the sensor surface 70 can be averaged to reduce the error.

As described above, according to the present embodiment, the force sensor S having the plurality of electrodes 62A, 62B, 62C, 62D and the sensor layer 64 from the pressure-sensitive material causes the sensor surface 70 acting on the sensor surface 70. Detects parallel forces. Therefore, according to the present embodiment, it is possible to detect a force parallel to the sensor surface 70 acting on the sensor surface 70 without requiring a complicated configuration.

On the other hand, the two-dimensional pressure sensor based on the background technology cannot detect a force parallel to the sensor surface acting on the sensor surface, unlike the force detecting device 100 according to the present embodiment described above. Hereinafter, this point will be described with reference to FIGS. 6 and 7. FIG. 6 is a plan view showing the structure of a cell array including a sensor cell of a two-dimensional pressure sensor according to the background technology. FIG. 7 is a plan view for explaining the electric resistance value of the sensor cell of the two-dimensional pressure sensor according to the background technology.

As shown in FIG. 6, the sensor array 310 in the two-dimensional pressure sensor 300 includes a plurality of sensor cells 360 arranged in a two-dimensional manner over a plurality of rows (for example, m rows) and a plurality of columns (for example, n columns).

Each sensor cell 360 includes one selection transistor M and a pressure sensor Sb using a pressure sensitive material. The pressure sensor Sb has two electrodes 362A and 362B and a sensor layer 364 made of a pressure-sensitive material formed on the two electrodes 362A and 362B. The sensor layer 364 is made of the same pressure-sensitive conductive material as the sensor layer 64.

The electrodes 362A and 362B are formed on the substrate via an insulating layer, respectively. The sensor layer 364 is formed on an insulating layer in which an opening 366 that exposes the electrodes 362A and 362B is formed, and is in contact with the electrodes 362A and 362B through the opening 366. In this way, the surface on the side where the sensor layer 64 is formed on the electrodes 362A and 362B becomes the sensor surface 370, which is the pressure detecting surface for detecting the pressure acting on the contacted object.

Each row of the sensor array 310 is provided with a plurality of gate lines GL1, GL2, ..., GLm, which are drive signal lines, extending in the row direction. Further, in each row of the sensor array 310, data lines DL1, DL2, ..., DLn which are output signal lines are arranged so as to extend in the column direction. The data lines DL1, DL2, ..., DLn are connected to one end of the resistor Rb included in the detection circuit, respectively. The other end of the resistor Rb is connected to the ground voltage line of the ground voltage VS. The input terminal of the A / D converter 368 included in the detection circuit is connected to the connection node between the data lines DL1, DL2, ..., DLn and one end of the resistor Rb.

The electrodes 362A and 362B of the sensor cell 360 located in the i-th row and the j-th column and the selection transistor M are connected as follows. That is, the gate electrode of the selection transistor M is connected to the corresponding gate line GLi of the i-th row. The source electrode of the selection transistor M is connected to the corresponding data line DLj in the jth column. The drain electrode of the selection transistor M is connected to the electrode 362A. Further, the electrode 362B is connected to a common power supply line to which the power supply voltage VD is supplied.

In the case of the two-dimensional pressure sensor 300 configured as described above, the pressure sensor Sb only has two electrodes 362A and 362B. Therefore, the two-dimensional pressure sensor 300, as shown in FIG. 7, only a resistance value _{R AC} between the electrode 362A and the electrode 362B can not be detected. As a result, although the two-dimensional pressure sensor 300 can detect the force acting perpendicularly to the sensor surface 370, that is, the pressure, unlike the force detecting device 100 according to the present embodiment, the two-dimensional pressure sensor 300 has a force on the sensor surface 370. Therefore, the force acting parallel to the sensor surface 370 cannot be detected.

[Second Embodiment]
The force detecting device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a plan view showing the structure of a cell array including a sensor cell in the force detection device according to the present embodiment. The same components as those of the force detection device according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified.

The basic configuration of the force detecting device according to the present embodiment is substantially the same as the configuration of the force detecting device 100 according to the first embodiment shown in FIGS. 1 and 2. In the force detection device according to the present embodiment, in the sensor cell 60, the connection of the selection transistors M1 and M2 to the first and second gate lines and the connection of the electrodes to the first and second power supply lines are the first embodiments. Some are different.

In the force detection device 200 according to the present embodiment, in the sensor array 10, the sensor cell 60a similar to the sensor cell 60 of the first embodiment and the sensor cell 60b having a different connection from the sensor cell 60 of the first embodiment are arranged in a row direction and a column. They are arranged alternately in the direction.

When the sensor cell 60b whose connection is different from that of the sensor cell 60 of the first embodiment is located in the x-th row and the y-th column, the electrodes 62A, 62B, 62C, 62D, and the selection transistors M1 and M2 of the force sensor S in the sensor cell 60b are , Are connected as follows. Note that x is an integer that satisfies 1 ≦ × ≦ m, and y is an integer that satisfies 1 ≦ y ≦ n.

That is, the gate electrode of the selection transistor M1 is connected to the corresponding first gate line GLxa in the xth row. The source electrode of the selection transistor M1 is connected to the corresponding data line DLy in the y-th column. The drain electrode of the selection transistor M1 is connected to the electrode 62B.

Further, the gate electrode of the selection transistor M2 is connected to the second gate line GLxb in the corresponding row x. The source electrode of the selection transistor M2 is connected to the corresponding data line DLy in the y-th column. The drain electrode of the selection transistor M2 is connected to the electrode 62C.

Further, the electrode 62A is connected to the corresponding first power supply line VLya in the y-th row. The electrode 62D is connected to the corresponding second power line VLYb in the y-th row.

Also in the present embodiment, the on / off state of the first and second gate lines can be switched, and the on / off state of the first and second power supply lines can be switched in the same manner as in the first embodiment. _{Thereby, the electric resistance values R AB} , R _AC , R _BD , and R _CD can be individually acquired for each sensor cell 60 in the sensor array 10. In this embodiment, the correspondence between the operation sequence and the acquired electrical resistance value is different from the correspondence in the first embodiment described above.

[Modification Embodiment]
The present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above embodiment, the case where each force sensor S has four electrodes 62A, 62B, 62C, and 62D has been described as an example, but the present invention is not limited thereto. The force sensor S may have a plurality of electrodes of three or more. In this case, each sensor cell 60 may have two or more active elements such as a plurality of selection transistors. By having three or more electrodes, it is possible to obtain electric resistance values between two or more sets of electrodes, and the sensor surface acting on the sensor surface based on the relative magnitude relationship of these electric resistance values. The direction of the force parallel to can be determined.

Further, in the above embodiment, the case where the selection transistors M1 and M2 of the thin film transistor or the like are used as active elements has been described as an example, but the present invention is not limited to this. Instead of the selection transistor M, another active element such as a MIM (Metal Insulator Metal) diode can be used. Each sensor cell may include an element having a memory property. The detection circuit 30 may obtain the outputs of the data lines DL1, DL2, ..., DLn by a method other than voltage such as current.

Further, in the above embodiment, an N-type thin film transistor is applied to the selection transistors M1 and M2, but the present invention is not limited to this. A P-type thin film transistor may be applied to the selection transistors M1 and M2. When a P-type thin film transistor is applied, the logic of the gate drive signal is opposite to that of the above embodiment, and the power supply potential supplied to the sensor cell and the ground potential are opposite to each other.

Further, in the above embodiment, the case where a plurality of sensor cells 60 are arranged in a rectangular grid pattern in the sensor array 10 has been described as an example, but the present invention is not limited to this. The plurality of sensor cells 60 can be arranged in two dimensions regularly or irregularly.

10 ... Sensor array 20 ... Gate line drive circuit 30 ... Detection circuit 40 ... Power supply line drive circuit 50 ... Control units 60, 60a, 60b ... Sensor cells 62A, 62B, 62C, 62D ... Electrodes 64 ... Sensor layer 70 ... Sensor surface 100, 200 ... Force detection device S ... Force sensor M1, M2 ... Selective transistor GLia ... 1st gate line GLib ... 2nd gate line VLja ... 1st power supply line VLjb ... 2nd power supply line DLj ... Data line

Claims (9)

A force sensor having three or more electrodes and a sensor layer formed on the three or more electrodes and made of a pressure-sensitive material.
Have a detection unit for detecting an electrical resistance value between the two or more sets of electrodes of said three or more electrodes of the force sensor,
Each of the plurality of sensor cells contains a plurality of active elements, and each of the plurality of sensor cells contains a plurality of active elements.
The three or more electrodes include a first electrode, a second electrode, a third electrode, and a fourth electrode.
A force detecting device , wherein the active element includes a first active element connected to the first electrode and a second active element connected to the fourth electrode. The force detecting device according to claim 1 , wherein each of the plurality of sensor cells includes the force sensor and is arranged in a two-dimensional manner. The active element, a force detection device according to claim 1, characterized in that the thin film transistor. A first drive signal line connected to the first active element and for driving the first active element, and
The force detecting device according to any one of claims 1 to 3, wherein the force detecting device is connected to the second active element and has a second driving signal line for driving the second active element. A first power supply line connected to the second electrode and for supplying a power supply voltage,
The force detecting device according to claim 1 , further comprising a second power supply line connected to the third electrode and for supplying a power supply voltage. The force detecting device according to any one of claims 1 to 5 , further comprising an output signal line connected to the first active element and the second active element. The first electrode, the second electrode, the third electrode, and the fourth electrode are arranged so as to be located at the four corners of the sensor layer.
The detection unit is between the first electrode and the second electrode, between the first electrode and the third electrode, between the second electrode and the fourth electrode, and the third electrode. The force detecting device according to any one of claims 1 to 6 , wherein the electric resistance value between the fourth electrode and the fourth electrode is detected. The force detecting device according to any one of claims 1 to 7 , wherein the three or more electrodes have the same planar shape as each other. The force detecting device according to any one of claims 1 to 8 , wherein the three or more electrodes are two-dimensionally arranged at equal intervals.

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