JP6354422B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure-sensitive sensor that measures pressure.

  A pressure-sensitive sensor is known in which a plurality of row / column electrodes coated with a conductive layer intersect each other (passive matrix structure) between two flexible film substrates. (For example, refer to Patent Document 1). In this type of pressure-sensitive sensor, when pressure is applied, conductive layers arranged in an intersecting manner come into contact with each other, thereby changing the resistance value. Then, by detecting this change in resistance value, the in-plane distribution of the applied pressure can be measured.

  In recent years, a thin film transistor (TFT) manufactured by a printing process has attracted attention (see, for example, Non-Patent Document 1). Here, the printing process refers to a method for producing a semiconductor element without using a vacuum process by coating or a printing method (inkjet, letterpress, intaglio, planographic, stencil, etc.). In the electronics field, which frequently uses vacuum processes, the printing process is promising as an innovative technology for production systems. In addition, it has been noticed that TFTs manufactured by a printing process have a large area, low cost, low environmental load, low temperature formation, and flexibility.

JP 2012-57992 A

"Special Feature: Flexible Organic Electronics for Next-Generation Display", Monthly OPTRONICS, Optronics, May 2011, Volume 30, Volume 353

  In the conventional pressure-sensitive sensor exemplified in Patent Document 1, the drive circuit IC and the detection circuit IC cannot be mounted on the film for reasons of cost and flexibility. Therefore, it was necessary to draw out all the wiring of the drive circuit and detection circuit formed in a matrix form to the outside of the film and connect to the external circuit (having drive and detection functions). The space for wiring layout has become enormous, causing a problem that the degree of freedom in sensor design is significantly reduced, which hinders the expansion of applications.

  It is an object of the present invention to provide a pressure-sensitive sensor having a large number of circuit lines constituting a pressure-sensitive sensor formed in a matrix and having a high degree of freedom in design without limiting flexibility. And

  In the present invention, the following features are provided alone or in combination as appropriate.

One aspect of the present invention for achieving the above object is that a first substrate on which a scan driving circuit (scan driver) including one or more shift registers is formed, and the first substrate are attached and mounted. A second substrate (upper matrix film) on which a plurality of drive electrodes connected to the scanning drive circuit are stacked, a third substrate (lower matrix film) on which a plurality of detection electrodes are stacked, and a second A pressure-sensitive conductive material layer laminated between the base material and the third base material, and the second base material has a surface on which the plurality of drive electrodes are formed on the third base material. The pressure-sensitive sensor is disposed so as to face, and a portion of the third base material facing the first base material is perforated .

  Further, the scan drive circuit (scan driver) can sequentially or collectively select the drive electrodes to which the drive voltage is applied from the plurality of drive electrodes, and the non-selected drive electrodes may be held in a high impedance state.

  Moreover, you may further provide the 4th base material in which the output selection circuit which has the 1 or more shift register connected to the 3rd base material and was connected to the some detection electrode was formed.

  Further, the output selection circuit (data selector) can select the detection electrodes for detecting the output voltage from the plurality of detection electrodes sequentially or collectively, and the non-selected detection electrodes may be held in a high impedance state.

The third base material is disposed such that the surface on which the fourth base material is pasted and mounted and the plurality of detection electrodes are formed faces the second base material. The portion facing the fourth base material may be perforated.

  The shift register included in the scan drive circuit and the output selection circuit may include an input TFT, a transfer TFT, a reset TFT, a shunt TFT, and an output TFT.

  According to the present invention, it is possible to provide a pressure-sensitive sensor having a large number of wirings constituting a pressure-sensitive sensor formed in a matrix and having a high degree of design freedom at a low cost without limiting flexibility. .

The block diagram of the pressure-sensitive sensor which concerns on one Embodiment of this invention. 1 is a circuit configuration diagram of a pressure-sensitive sensor according to an embodiment of the present invention. Explanatory drawing of the film sticking structure of the scan driver and data selector concerning one Embodiment of this invention Explanatory drawing of printing TFT layer structure concerning one embodiment of the present invention Explanatory drawing of reduction of lead wiring according to an embodiment of the present invention Circuit explanatory diagram of a shift register (for one stage) according to an embodiment of the present invention The figure explaining the phase relation of input signals CK + and CK- concerning one embodiment of the present invention The figure explaining the timing of input signals CK1 and CK2 concerning one embodiment of the present invention

  An embodiment of a pressure sensor according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an embodiment of a pressure-sensitive sensor according to the present invention. FIG. 1A is a cross-sectional view showing an initial state and a pressure state of the pressure sensor, and FIG. 1B is a perspective view in which the layers and the film of the pressure sensor are disassembled. The pressure-sensitive sensor includes a first substrate on which a scan driver 6 (scan driving circuit) including one or more shift registers is formed, and a plurality of driving electrodes 1 connected to the scan driver 6 (scan driving circuit). Are laminated on one side, an upper matrix film 4 (second base material), a lower matrix film 5 (third base material) on which a plurality of detection electrodes 2 are laminated, an upper matrix film 4 and a lower part And a pressure-sensitive conductive material layer 3 laminated between the matrix film 5. Further, the fourth base material laminated on the lower matrix film 5 is further formed with a data selector 7 (output selection circuit) including one or more shift registers connected to the plurality of detection electrodes 2. . When the upper matrix film 4 and the lower matrix film 5 are laminated, the drive electrode 1 and the detection electrode 2 are arranged so as to intersect each other in plan view, and their intersections via the pressure-sensitive conductive material layer 3 Each constitutes an array of pressure sensitive sensors. The drive electrode 1 and the scan driver 6 are laminated on the surface of the upper matrix film 4 that faces the pressure-sensitive conductive material layer 3. In addition, it is preferable that the 1st thru | or 4th base material is a film base material which has flexibility.

  FIG. 2 is a diagram illustrating a circuit configuration of an embodiment of the pressure-sensitive sensor according to the present invention. Each of the scan driver 6 and the data selector 7 is a circuit composed of a TFT and a thin film capacitor, and is a film substrate (first substrate and fourth substrate) different from the upper matrix film 4 and the lower matrix film 5. The upper matrix film 4 and the lower matrix film 5 are respectively mounted by being laminated by using a printing process. Hereinafter, unless otherwise specified, the first base material and the scan driver 6 stacked thereon are simply referred to as a scan driver 6, and the fourth base material and the data selector 7 stacked thereon are simply referred to as a data selector. Call it 7.

  The scan driver 6 has a function of sequentially selecting each drive electrode 1 and applying a drive voltage V <b> 2 to the selected drive electrode 1. When not selected, the drive electrode 1 is maintained in a high impedance state. By setting all of the input signals ST1, CK1 +, CK1-, and V1 to the L level voltage, all the drive electrodes 1 can be simultaneously selected.

  The data selector 7 has a function of sequentially selecting an electrode for detecting an output voltage from each detection electrode 2. When not selected, the detection electrode 2 is held in a high impedance state. By making all the input signals ST2, CK2 +, CK2-, and V1 have L level voltages, all the detection electrodes can be simultaneously selected.

  The electrostatic protection element 8 in the scan driver 6 and the data selector 7 is a floating gate TFT type protection element that can be formed by using the gate terminal of the TFT as a floating terminal.

  In this embodiment, a p-type TFT is used, but an n-type TFT may be used. In that case, the phase of the input / output signal is inverted.

  FIG. 3 is a diagram for explaining a pasting structure of the scan driver 6 and the data selector 7. As shown in FIG. 3A, the lower matrix film 5 has an upper surface on which the data selector 7 and the plurality of drive electrodes 1 are stacked so that excessive pressure is not applied to the scan driver 6 and the data selector 7. It is laminated so as to face the matrix film 4, and the portion facing the data selector 7 of the upper matrix film 4 is punched. Further, as shown in FIG. 3B, the upper matrix film 4 is laminated so that the surface on which the scan driver 6 and the plurality of drive electrodes 1 are laminated faces the lower matrix film 5, and the lower matrix film 4 is laminated. The part of the film 5 facing the scan driver 6 is perforated.

  FIG. 4 is a diagram for explaining the layer structure of TFTs used for the scan driver 6 and the data selector 7. A flexible film substrate 9 (corresponding to a first substrate and a fourth substrate), a gate electrode layer 10, a gate insulating layer 11, a source / drain electrode layer 12, and a semiconductor layer 14; The semiconductor protective layer 15, the interlayer insulating layer 16, and the interlayer wiring layer 17 are provided. All layers except the film substrate can be formed using various printing methods such as letterpress printing, reverse offset printing, gravure printing, and screen printing. If a printing method is used, it is easier to form on a flexible substrate such as a film because it is easier to form in a low temperature environment than a vacuum film forming method.

  FIG. 5 is a diagram for explaining the concept of lead-out wiring reduction. As shown in FIG. 5A, in the case of the wiring lead configuration according to the prior art, in the case of m rows and n columns, it is necessary to draw m + n wirings to the outside.

  As shown in FIG. 5B, the number of lead lines according to the present embodiment is ten (COM, V1, V2, ST1, ST2, CK1 +, CK1-, CK2 +, CK2-, VOUT). ). In this embodiment, since the number of lead wires does not depend on m and n, the effect of reducing lead wires is increased as m and n in the matrix increase.

  Next, the shift register (for one stage) which is a structural unit of the scan driver 6 and the data selector 7 will be described in detail.

  FIG. 6 is a diagram illustrating the circuit configuration and operation of the shift register (for one stage). FIG. 7 is a diagram illustrating the phase relationship between the input signals CK + and −. The shift register includes an input TFT 18 having a function of injecting (charging) an input signal (potential / charge) into the holding capacitor 23, a transfer TFT 19 having a function of transferring a signal (potential / charge) to the input TFT 18 of the next stage, A reset TFT 20 having a function of discharging (discharging) charges from the holding capacitor, and a shunt TFT 21 having a function of discharging charges leaked from the transfer TFT 19 which is turned off to V1 in a non-selection period (TRN is in the H level) , V2 is output to OUT only during the selection period (TRN is L level), and the output TFT 22 has a function of setting OUT to a high impedance state during the non-selection period, and has a function of holding an input signal (potential / charge). A holding capacitor 23 and a stabilization capacitor 24 having a function of stabilizing the potential of TRN are provided. . The shunt TFT 21 is desirably designed to be smaller in size (channel width / channel length) to about 1/10 or less than the transfer TFT 19.

  In each stage shift register, the clock signal CK is connected to the transfer TFT 19 and the high level constant voltage source V1 is connected to the reset TFT 20, and the low level pulse of the input signal IN is inputted to the input TFT 18 at the timing when CK is at the high level. Then, the transfer TFT 19 outputs a low level pulse signal TRN delayed from the IN by CK half cycle. The output TFT 22 is driven by the TRN pulse and is turned on. Immediately after outputting the TRN pulse, it is necessary to input the RST pulse to the reset TFT 20 and reset the low level potential held at the node NA to the high level.

  The single stage shift register of FIG. 6 is connected in series in multiple stages as shown in FIG. 2 (adjacent front stage OUT and rear stage IN are connected, and rear stage OUT is also connected to front stage RST). The clock signals CK + and CK− whose phases are inverted shown in FIG. 7 are connected, and the trigger pulse signal ST is input to the first stage IN and the final stage RST (the pulse timing of the first stage IN and the final stage RST is changed). It is necessary to adjust the pulse period according to the total number of stages so as to be simultaneous), and a circuit for sequentially applying a scanning pulse to each drive electrode and each detection electrode can be realized.

  FIG. 8 is a diagram illustrating the timing of the input signals CK1 and CK2 of the scan driver 6 and the data selector 7. Note that the pulse widths of the input signals ST1 and ST2 are preferably equivalent to a half cycle of the input signals CK1 and CK2.

  In a printing process where wet film formation is a principle, patterning restrictions on fine shapes are severer than in vacuum processes and other semiconductor processes using photolithography. Therefore, it can be said that it is relatively unsuitable to manufacture a circuit in which a large number of TFTs are connected in a complicated manner. In view of this situation, the shift register of FIG. 6 has a simple circuit configuration in which a shunt TFT 21 and a capacitor are added to the minimum necessary components (input TFT 18, transfer TFT 19, reset TFT 20, and output TFT 22).

  According to the embodiment disclosed above, the number of lead-out wirings to the outside can be reduced without impairing the flexibility of the pressure-sensitive sensor, and the space for connection terminals and wiring layout can be reduced. It becomes easy to increase the number of detection electrodes.

  In addition, the scan driver 6 and the data selector 7 are each formed on a base material different from the base material on which the drive electrode 1 and the detection electrode 2 are formed, and are attached to each other. 4 and the lower matrix film 5) can be manufactured without depending on the size thereof, and it becomes easy to handle pressure-sensitive sensors of various sizes / shapes.

  In addition, when the upper matrix film 4 and the lower matrix film 5 are bonded together, the portion facing the scan driver 6 of the lower matrix film 5 and the portion located in the data selector 7 of the upper matrix film 4 are respectively pierced. Thus, it is possible to prevent excessive pressure from being applied to the scan driver 6 and the data selector 7 and to prevent the occurrence of circuit breakage such as disconnection.

  Further, the shift register included in the scan driver 6 and the data selector 7 has a circuit structure by adopting a minimum necessary circuit configuration including an input TFT, a transfer TFT, a reset TFT, a shunt TFT, and an output TFT. Can be produced inexpensively by a printing process without being complicated.

  The present invention can be expected to be applied to fields such as electronics, robotics, and mechanical engineering.

DESCRIPTION OF SYMBOLS 1 Drive electrode 2 Detection electrode 3 Pressure sensitive conductive material layer 4 Upper matrix film (2nd base material)
5 Lower matrix film (third substrate)
6 Scan driver (scan drive circuit)
7 Data selector (output selection circuit)
8 Electrostatic protection element (floating gate TFT type)
DESCRIPTION OF SYMBOLS 9 Film base material 10 Gate electrode layer 11 Gate insulating layer 12 Source / drain electrode layer 14 Semiconductor layer 15 Semiconductor protective layer 16 Interlayer insulating layer 17 Interlayer wiring layer 18 Input TFT
19 Transfer TFT
20 Reset TFT
21 Shunt TFT
22 Output TFT
23 holding capacitor 24 stabilizing capacitor

Claims (6)

A first substrate on which a scan driving circuit including one or more shift registers is formed;
A second base material on which the first base material is pasted and mounted, and a plurality of drive electrodes connected to the scan drive circuit are formed;
A third substrate on which a plurality of detection electrodes are formed;
A pressure-sensitive conductive material layer laminated between the second base material and the third base material ;
The second base material is disposed so that a surface on which the plurality of drive electrodes are formed faces the third base material, and the first base material of the third base material A pressure-sensitive sensor that has been pierced through   2. The pressure-sensitive sensor according to claim 1, wherein the scanning drive circuit can sequentially or collectively select drive electrodes to which a voltage is applied from the plurality of drive electrodes, and the non-selected drive electrodes are held in a high impedance state. . Affixed mounted on the third substrate, further Ru comprising a fourth substrate to the output selection circuit is formed having one or more shift registers connected to the plurality of detection electrodes, according to claim 1 or 2 The pressure-sensitive sensor described in 1.   The pressure-sensitive sensor according to claim 3, wherein the output selection circuit can sequentially or collectively select detection electrodes for detecting an output voltage from the plurality of detection electrodes, and the non-selected detection electrodes are held in a high impedance state. Sensor. The third base material is disposed such that the fourth base material is pasted and mounted, and the surface on which the plurality of detection electrodes are formed faces the second base material,
The pressure-sensitive sensor according to claim 3 or 4, wherein a portion of the second base material facing the fourth base material is perforated. The shift register has an input TFT and, a transfer TFT, including a reset TFT, a shunt TFT, and an output TFT, pressure-sensitive sensor according to any one of claims 1 to 5.

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