JP2020177477A - Capacitive panel sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily conduct heat conduction from a heater or a cooler arranged in a lower part of a capacitance type panel sensor to a detection object placed in an upper part of a capacitance type panel sensor. To provide a panel sensor. SOLUTION: A transmitting electrode wire 11 of a transmitting electrode wire group pattern and a receiving electrode wire 12 of a receiving electrode wire group pattern are orthogonal to each other and are separated from each other on the front and back surfaces of a PET film 10, and the transmitting electrode wire 11 and the receiving electrode wire 12 are arranged. A capacitance type panel sensor 1 that detects a change in capacitance of a detection object on a sensor substrate 2 in which intersections are formed in a matrix, and receives the signal on the surface side of a PET film 10 on which the detection object is placed. The receiving electrode wire 12 of the electrode wire group pattern is arranged, the transmitting electrode wire 11 of the transmitting electrode wire group pattern is arranged on the back surface side of the PET film 10, and the transmitting electrode wire 11 of the transmitting electrode wire group pattern is further conductive on the back surface side of the transmitting electrode wire 11. The plate 18 is arranged. Further, the line width of the transmitting electrode line 11 is wider than the line width of the receiving electrode line. [Selection diagram] Fig. 1

Description

INDUSTRIAL APPLICABILITY According to the present invention, a capacitance capable of satisfactorily conducting heat conduction from a heater or a cooler arranged below the capacitance type panel sensor to a detection object placed above the capacitance type panel sensor. Regarding type panel sensors.

Capacitive touch panels are often used in input / output devices. The capacitance type touch panel has an advantage that a thick and hard decorative panel such as glass or acrylic can be used on the sensor surface. Capacitive touch panels combine transparent electrodes that are patterned vertically and horizontally, and when a finger is brought close to the surface of the sensor panel, a capacitance change occurs in the electrode in the close area, and the position of the finger is determined by detecting this capacitance change. Identify.

Japanese Unexamined Patent Publication No. 2016-50245

By the way, the capacitance type touch panel is arranged on the upper surface of the product shelf or the warehouse shelf of the showcase, and the capacitance type panel detects an object to be detected such as a product placed on the upper surface of the capacitance type touch panel. It can be used as a sensor. Here, when a capacitance type touch panel is provided on a product shelf or the like, when the product shelf is made of plate-shaped tempered glass to have rigidity and strength, the dielectric constant of this tempered glass is high, so that the capacitance type panel Even if the object to be detected is placed on the upper surface of the sensor, the displacement current is drawn to the tempered glass side, the flow of the displacement current to the object to be detected decreases, and the change in capacitance becomes small. As a result, there is a problem that the detection sensitivity to the detection target is low.

In order to solve this problem, in the capacitance type panel sensor, an air layer made of foamed ABS or the like is provided under the sensor substrate in which the intersections of the transmitting electrode lines and the receiving electrode lines are formed in a matrix.

However, when this air layer is provided, when a heater or cooler is provided on the product shelf, the thickness between the heater or cooler and the detection object on the capacitance type panel sensor is large, so that the detection target is provided. The problem of poor heat conduction arises.

The present invention has been made in view of the above, and the heat from the heater or cooler arranged in the lower part of the capacitance type panel sensor to the detection object placed in the upper part of the capacitance type panel sensor. An object of the present invention is to provide a capacitance type panel sensor capable of performing good conduction.

In order to solve the above-mentioned problems and achieve the object, in the capacitance type panel sensor according to the present invention, the transmitting electrode line of the transmitting electrode line group pattern and the receiving electrode line of the receiving electrode line group pattern are orthogonal to each other. Detects changes in capacitance at each intersection when a detection object is placed on a sensor substrate that is separated from the front and back of the sheet and has a matrix of intersections between the transmission electrode line and the reception electrode line. In the capacitance type panel sensor, the receiving electrode line of the receiving electrode line group pattern is arranged on the front surface side of the electrode sheet on which the detection object is placed, and the transmitting electrode line group is arranged on the back surface side of the electrode sheet. The transmission electrode line of the pattern is arranged, and a conductive plate is further arranged on the back surface side of the transmission electrode line of the transmission electrode line group pattern.

Further, the capacitance type panel sensor according to the present invention is characterized in that, in the above invention, the line width of the transmitting electrode line is wider than the line width of the receiving electrode line.

Further, the capacitance type panel sensor according to the present invention is characterized in that, in the above invention, the line width of the transmission electrode line is a mesh pattern.

Further, in the capacitance type panel sensor according to the present invention, in the above invention, the detection object is a product displayed on a product shelf, the sensor substrate is arranged on the product shelf, and the product shelf. A heater or a cooler is arranged on the upper surface side of the above.

Further, in the capacitance type panel sensor according to the present invention, in the above invention, the detection object is placed in the same phase as the transmission signal by using the transmission signal input to the transmission electrode line. Difference between the reference signal generation unit that generates a reference signal having a waveform that has a capacitance equivalent to the capacitance of the intersection when the signal is not provided, and the reception signal from the reception electrode line and the reference signal. It is characterized by including a differential amplifier that outputs an amplified signal as a detection signal.

According to the present invention, it is possible to satisfactorily conduct heat conduction from a heater or a cooler arranged under the capacitance type panel sensor to an object to be detected mounted on the upper part of the capacitance type panel sensor.

FIG. 1 is a perspective view showing the overall configuration of the capacitance type panel sensor according to the embodiment of the present invention. FIG. 2 is a diagram showing a cross-sectional configuration of the capacitance type panel sensor shown in FIG. FIG. 3 is a diagram showing the arrangement relationship between the transmission electrode line and the reception electrode line on the sensor substrate. FIG. 4 is a circuit diagram showing an example of a drive circuit on the sensor substrate. FIG. 5 is a diagram showing an example of a bottom surface shape image generated based on the detected value of the capacitance type panel sensor. FIG. 6 is a diagram showing the flow of electric lines of force and current in the vicinity of the intersection of the transmitting electrode line and the receiving electrode line. FIG. 7 is a diagram showing an example in which the width of the transmitting electrode line is wider than the width of the receiving electrode line. FIG. 8 is a diagram showing an example in which the transmission electrode line has a mesh pattern.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

<Overall configuration>
FIG. 1 is a perspective view showing the overall configuration of the capacitance type panel sensor 1 according to the embodiment of the present invention. Further, FIG. 2 is a diagram showing a cross-sectional configuration of the capacitance type panel sensor 1 shown in FIG. The capacitance type panel sensor 1 is a sensor that detects the presence or absence of a detection object mounted on the surface side (+ Z direction) by changing the capacitance. For example, it detects the presence or absence of products such as canned beverages, PET bottles, cigarettes, and medicines placed on the product shelves of showcases. As shown in FIG. 1, the capacitance type panel sensor 1 is a sensor substrate 2 having a detection area E on which a detection object is placed and a matrix drive unit EA.

As shown in FIG. 2, in the sensor substrate 2, a transmission electrode line pattern composed of a plurality of transmission electrode lines 11 is drawn on the back surface (−Z direction) of the PET film 10 which is an electrode sheet, and a plurality of reception electrode lines are drawn on the front surface. A receiving electrode line pattern consisting of 12 is drawn. The plurality of transmission electrode wires 11 extend in the X direction and are arranged in parallel at a predetermined pitch. The plurality of receiving electrode wires 12 extend in the Y direction and are arranged in parallel at a predetermined pitch. The plurality of transmitting electrode lines 11 and the plurality of receiving electrode lines 12 are separated from each other at intervals of the thickness of the PET film 10, and the intersections of the plurality of transmitting electrode lines 11 and the plurality of receiving electrode lines 12 as viewed from the Z direction are formed. Arranged in a matrix. The capacitance type panel sensor 1 detects the change in capacitance at each intersection and generates a two-dimensional change image of capacitance to detect the presence or absence of a detection object placed on the upper part. Can be done.

PET films 14 and 16 as protective films are laminated on the front surface side of the receiving electrode line pattern and the back surface side of the transmitting electrode line pattern, respectively, via double-sided tapes 13 and 15, respectively.

Further, a conductive plate 18 is arranged on the back surface side (−Z direction) of the PET film 16 via the double-sided tape 17. The conductive plate 18 is provided to transfer heat from the lower portion (−Z direction) to the upper portion. The reason why the conductive plate 18 is made flat is to transfer heat uniformly to the upper sensor substrate 2. The conductive plate 18 is, for example, aluminum.

The sensor board 2 is connected to the detection unit 3 via the connector 1a. The detection unit 3 outputs a transmission signal to the transmission electrode line 11, receives the detection signal output from the reception electrode line 12, and detects the presence or absence of the detection target object.

<Detection operation>
Next, the operation of the capacitance type panel sensor 1 will be described. As shown in FIG. 3, in the capacitance type panel sensor 1, a plurality of transmission electrode lines 11 and a plurality of reception electrode lines 12 are arranged orthogonally with the PET film 10 interposed therebetween.

As shown in FIG. 4, the intersections where the plurality of transmitting electrode lines 11 and the plurality of receiving electrode lines 12 are orthogonal to each other are separated by the thickness interval of the PET film 10, so that a coupling capacitance Ce is generated. In this state, when the detection unit 3 applies a 30 V rectangular wave signal Si to the transmission electrode line 11, the detection signal SB corresponding to each intersection is output from the reception electrode line 12.

The rectangular wave signal Si, which is a transmission signal input from the detection unit 3, is output to each transmission electrode line 11 via the selector 20. At this time, the rectangular wave signal Si is amplified by the amplifier 21. From each receiving electrode line 12, the detection signal generated at each intersection with each transmitting electrode line 11 is output via the selector 22, and then the detection signal SB amplified by the amplifier 23 is output to the + end of the differential amplifier 31. Output to.

On the other hand, the gain adjustment amplifier 30 amplifies the transmission signal Si via the capacitor 33 having the capacitance Cc connected to the transmission line 11a, and the amplified calibration signal SC is used as a reference signal for the differential amplifier 31. Output to the edge. The calibration signal SC is a signal that simulates the detection signal SB0 in a state where the detection object is not placed on the surface of the capacitance type panel sensor 1, and the gain adjustment amplifier 30 is input via the capacitor 33. The gain of the transmitted signal Si to be output is adjusted.

The differential amplifier 31 outputs the difference obtained by subtracting the calibration signal SC from the detection signal SB to the detection unit 3 as an amplified detection signal SA.

The capacitor 33 and the gain adjustment amplifier 30 function as a reference signal generation unit, and if the reference signal generation unit and the differential amplifier 31 are not provided, the detection signal SB is output to the detection unit 3 as it is. Here, assuming that the detection signal SB in which the detection target is placed is the detection signal SB1 and the detection signal SB in which the detection target is not placed is the detection signal SB0, the detection unit 3 calls the detection signal SB0. Based on the difference ΔSB from the detection signal SB1, the presence / absence of the detection target is detected. Here, when the object to be detected has a low dielectric constant such as cigarettes, the change in capacitance is small and the difference ΔSB is extremely small. Therefore, if the gain of the amplifier 23 is increased or an amplifier is provided at a higher stage to increase the gain, the dynamic range of the A / D conversion input of the detection unit 3 is exceeded, and the presence or absence of the detection target is detected. I can't.

Therefore, in the present embodiment, the reference signal generator and the differential amplifier 31 are provided to generate the calibration signal SC, and the differential amplifier 31 amplifies the detection signal SA obtained by subtracting the calibration signal SC from the detection signal SB. It is output to the detection unit 3. The calibration signal SC has a value close to the detection signal SB0. The detection signal SA0 is a signal amplified by subtracting the calibration signal SC from the detection signal SB0, and the detection signal SA1 is a signal amplified by subtracting the calibration signal SC from the detection signal SB1. The difference ΔSA between the detection signal SA0 and the detection signal SA1 is a value that is sufficiently within the dynamic range of the A / D conversion input, and is a value obtained by expanding the difference ΔSB. As a result, even when the object to be detected has a low dielectric constant such as cigarettes and the change in capacitance is small, the detection sensitivity can be improved within the dynamic range of the A / D conversion input.

FIG. 5 is a diagram showing an example of a bottom surface shape image D generated based on the value of the detection signal SA. This bottom shape image D is a two-dimensional image of the XY plane. FIG. 5 shows a bottom surface shape image D when a cigarette is placed on the capacitance type panel sensor 1. Image Da appears at a two-dimensional position corresponding to the bottom surface of the PET bottle in the bottom shape image D. The detection unit 3 outputs the bottom surface shape image D to an external device (not shown) that uses the bottom shape image D.

<Details of detection operation>
FIG. 6 is a diagram showing a state of electric lines of force generated between a transmitting electrode line 11 and a receiving electrode line 12 of the A portion, which is an intersection shown in FIG. 4, and a current flow. First, the rectangular wave signal Si transmitted from the detection unit 3 flows through the transmission electrode line 11 as an input current i. As for the input current i, the output current i0, which is the displacement current via the coupling capacitance Ce, flows through the receiving electrode line 12 at the intersection of the receiving electrode lines 12. Here, the lines of electric force between the transmitting electrode wire 11 and the receiving electrode wire 12 are directed to the detection target 100 side when the detection target 100 is placed on the upper part of the capacitance type panel sensor 1. The lines of electric force increase, and a minute displacement current flows as a leakage current i1 with respect to the object to be detected 100. As a result, the output current flowing through the receiving electrode wire 12 becomes the output current (i0-i1) obtained by subtracting the leakage current i1 minutes from the output current i0. This difference is the above difference ΔSB.

On the other hand, a capacitor 33 is connected to the transmission line 11a, and the displacement current (calibration current) via the capacitor 33 flows to the gain adjustment amplifier 30 side as the output current i0'. As a result, in the differential amplifier 31, the detection current SA0 when the detection object 100 is not placed becomes a value amplified by a predetermined gain G by subtracting the output current i0'from the output current i0. Further, the detection current SA1 when the detection object 100 is placed is a value amplified by a predetermined gain G by subtracting the leakage current i1 and the output current i0'from the output current i0. Here, when the values of the output current i0 and the output current i0'are close to each other, the detection current SA0 becomes almost 0, the detection current SA1 becomes (-i1), and the leakage current flowing through the detection target 100 Only i1 can be detected.

The gain of the gain adjusting amplifier 30 can be set in advance according to the dielectric constant, the shape, and the like of the detection object 100 mounted on the capacitance type panel sensor 1. When the permittivity of the detection object 100 is low and the difference ΔSB is small, the gain is adjusted so that the values of the output current i0 and the output current i0'are close to each other, and the permittivity of the detection object 100 is high. When the difference ΔSB is large, the gain may be adjusted so that the value of the output current i0'is smaller than the output current i0. That is, the gain is adjusted so that the difference ΔSA is within the dynamic range of the A / D conversion input and becomes a large value.

<Structure of transmission electrode wire>
As shown in FIG. 7, in the sensor substrate 2, the receiving electrode line group pattern in which the receiving electrode line 12 is formed is formed on the front surface of the PET film 10, and the transmitting electrode line 11 is formed on the back surface of the PET film 10. A transmission electrode line group pattern is formed.

Then, the conductive plate 18 is arranged below the transmission electrode line group pattern. Therefore, the electric lines of force from the transmission electrode wire 11 are drawn into the conductive plate 18 in a large amount, and the change in capacitance with respect to the detection object 100 arranged at the upper portion becomes small.

Therefore, in the present embodiment, the line width W2 of the transmitting electrode wire 11 is made larger than the line width W1 of the receiving electrode wire 12, and the transmitting electrode wire 11 shields the lower portion from the transmitting electrode wire 11 to the lower portion. It prevents the electric power lines from concentrating on the conductive plate 18 of the above.

FIG. 8 is a diagram showing an example of a pattern of the transmitting electrode line 11 and the receiving electrode line 12. As shown in FIG. 8, the transmission electrode line 11 substantially shields the plane on which the transmission electrode line group pattern is formed. The transmission electrode line 11 may be a rectangular solid electrode pattern, but is a mesh pattern in order to reduce the amount of ink used to form the transmission electrode line group pattern. The central portion 11b of the transmission electrode wire 11 has a mesh line width wider than that of the other meshes. The area of the transmission electrode line group pattern, which is the mesh pattern, is about 50% of the area of the detection area of the PET film 10. That is, the amount of ink is half that of the solid electrode pattern.

When the electrode pattern is a mesh pattern, the transmission electrode line group pattern may be formed by the additive method, and when the transmission electrode line is a solid electrode pattern, it may be formed by the subtractive method.

In the above embodiment, the capacitor 33 is directly connected to the transmission line 11a to directly acquire the square wave signal Si from the transmission line 11a, but the present invention is not limited to this, and is the latter stage of the amplifier 21. , A calibration electrode line orthogonal to the transmission electrode line 11 is provided outside the detection region E, a capacitor is provided between each transmission electrode line 11 and the calibration electrode line, and a square wave signal Si is transmitted via the calibration electrode line. You may try to get it.

Further, instead of the calibration electrode wire, a flat plate calibration electrode wire having a solid wiring pattern is provided, and the transmission electrode wire 11 and the flat plate calibration electrode wire are electrostatically coupled to each other so that capacitance can be generated for each. May be good. The flat plate calibration electrode wire, which is a wiring pattern, is formed on the receiving electrode wire group pattern side of the PET film 10 which forms the transmitting electrode wire group pattern and the receiving electrode wire group pattern on the front and back sides. Further, the flat plate calibration electrode wire is provided after the amplifier 21 and outside the detection region E, like the calibration electrode wire.

Further, in the above embodiment, the gain of the gain adjusting amplifier 30 is adjusted according to the detection target mounted on the capacitance type panel sensor 1, but a plurality of different capacitors are previously connected to the transmission line 11a. After connecting, a plurality of capacitors corresponding to the detection target mounted on the capacitance type panel sensor 1 are selected by the selector, and the rectangular wave signal Si passing through the selected capacitors is input to the gain adjustment amplifier 30. You may do so. In this case, the gain adjustment amplifier 30 is not adjusted, and only the selector selection setting is sufficient.

The capacitance type panel sensor 1 shown in the present embodiment and the modified example can be applied to other than the product shelf and the warehouse shelf of the showcase. For example, by providing the capacitance type panel sensor 1 on a transport path such as a belt conveyor, it is possible to detect the shape and material of an article to be transported in a heated or cooled state.

In addition, each configuration shown in the above-described embodiment and modification is a schematic function, and does not necessarily have to be physically shown. That is, the form of distribution / integration of each device and component is not limited to the one shown in the figure, and all or part of the device and components are functionally or physically distributed / integrated in arbitrary units according to various usage conditions. Can be configured.

1 Capacitance type panel sensor 1a Connector 2 Sensor board 3 Detection part 10, 14, 16 PET film 11 Transmission electrode line 11a Transmission line 11b Central part 12 Reception electrode line 13, 15, 17 Double-sided tape 18 Conductive plate 20, 22 Selector 21,23 Amplifier 30 Gain adjustment amplifier 31 Differential amplifier 33 Capacitor 100 Detection target Cc Capacitance Ce Coupling capacity D Bottom shape image Da Image E Detection area EA Matrix drive unit G Predetermined gain i Input current i0, i0'Output current i1 Leakage current SA, SA0, SA1, SB, SB0, SB1 Detection signal SC calibration signal Si rectangular wave signal W1, W2 Line width ΔSA, ΔSB difference

Claims (5)

The transmitting electrode line of the transmitting electrode line group pattern and the receiving electrode line of the receiving electrode line group pattern are orthogonal to each other and are separated from each other on the front and back surfaces of the electrode sheet, and the intersections of the transmitting electrode line and the receiving electrode line are formed in a matrix. A capacitance type panel sensor that detects changes in capacitance at each intersection when an object to be detected is placed on the sensor substrate.
The receiving electrode wire of the receiving electrode wire group pattern is arranged on the surface side of the electrode sheet on which the detection object is placed.
The transmission electrode wire of the transmission electrode wire group pattern is arranged on the back surface side of the electrode sheet.
A capacitance type panel sensor characterized in that a conductive plate is further arranged on the back surface side of the transmission electrode line of the transmission electrode line group pattern. The capacitance type panel sensor according to claim 1, wherein the line width of the transmitting electrode line is wider than the line width of the receiving electrode line. The capacitance type panel sensor according to claim 2, wherein the line width of the transmission electrode line is a mesh pattern. The detection object is a product displayed on a product shelf, the sensor substrate is arranged on the product shelf, and a heater or a cooler is arranged on the upper surface side of the product shelf. Item 4. The capacitance type panel sensor according to any one of Items 1 to 3. Using the transmission signal input to the transmission electrode line, the capacitance is in phase with the transmission signal and has the same capacitance as the capacitance at the intersection when the detection object is not placed. A reference signal generator that generates a reference signal with a waveform
A differential amplifier that outputs a signal obtained by amplifying the difference between the received signal from the receiving electrode line and the reference signal as a detection signal, and
The capacitance type panel sensor according to any one of claims 1 to 4, wherein the capacitance type panel sensor is provided.

Images