JP2021099297A - Capacitance type touch sensor - Google Patents

Abstract

To provide a capacitance type touch sensor capable of coping with a detection region of a relatively large area even in a simple constitution and applying even when the detection region is a flat surface and a curved surface.SOLUTION: A capacitance type touch sensor 1 includes: a conductive metallic sheet 2 functioning as a counter electrode; a detection electrode 3 provided at a position close to the metallic sheet 2 and electrically insulated from the metallic sheet 2; a capacitance type detection circuit 4 electrically connected to the detection electrode 3 and having a current detection section 41; and a power source 5 for supplying power to the capacitance type detection circuit 4. The capacitance type touch sensor is configured to detect a total value Cs of a first capacitance Cs1 which is a capacitance between the metallic sheet 2 and an object H to be detected, and a second capacitance Cs2 which is a capacitance between the metallic sheet 2 and the detection electrode 3 in the current detection section 41.SELECTED DRAWING: Figure 1

Description

The present invention relates to a capacitive touch sensor.

Conventionally, for example, as shown in FIG. 5, a detection electrode A2 made of a flat metal plate arranged in a detection region, a charging system A50 having a DC power supply A5, and a discharging system A40 having a current detecting means A41 have been used. A switch A42 for alternately switching between the charging system A50 and the discharging system A40 at a predetermined switching frequency is provided for the detection electrode A2, and the capacitance Cs between the object to be detected such as a person H and the detection electrode A2 is discharged. A capacitive touch sensor A1 (capacitive touch switch) that detects as a current flowing through the system A40 is known (Patent Document 1).

In the above patent document, the switching frequency fo of the switch A42 (indicated by a schematic analog switch in FIG. 5) is set to, for example, about several tens of kHz to several hundreds of kHz, and the voltage of the DC power supply A5 is set to Vo. Assuming that the capacitance between the detection electrode A2 and the object H to be detected is Cs, the charge Q (unit: coulomb) supplied to the detection electrode A2 is represented by Q = Cs · Vo × fo (1). The current when a charge of 1 coulomb is carried per second is 1A), and the charge Q discharged from the detection electrode A2 to the discharge system A40 is represented by Q = Is · t, where t is the time. Since the equation Is = (Cs · Vo × fo) / t holds and t = 1 sec when considering the current, the point where Is = Cs · Vo × fo and the charge of the electrostatic charge Cs possessed by the detection electrode A2 It is a discharge, and the current flowing through the discharge system depends solely on the capacitance Cs of the detection electrode A2, and these points are disclosed.

In addition, a conductive woven fabric in which the entire woven fabric that can be adapted to a spherical surface or a free curved surface functions as a sensor has also been devised. Specifically, two conductive cloths woven using a conductive thread having conductivity and an insulating thread having insulation are provided, and these conductive cloths are overlapped and integrated face-to-face, and each conductive cloth is integrated. Patent Document 2 below discloses a conductive fabric that functions as a touch sensor that detects a change in pressure applied between each conductive cloth by utilizing a change in capacitance between the conductive threads of the cloth.

Japanese Unexamined Patent Publication No. 2003-202383 (Patent No. 4035418) Japanese Unexamined Patent Publication No. 2011-102457 (Patent No. 5668966)

However, in the case of the above-mentioned capacitance type touch sensor shown in FIG. 5, if the area of the detection electrode A2 is increased, the capacitance Cs increases proportionally, and it becomes difficult to detect the switch A42 in terms of speed. The area of the detection electrode is limited to a certain size (about 10 mm × 10 mm), and the size of the detection area is also limited. Further, since the detection electrode A2 arranged in the detection region is made of a flat metal plate, when the detection region is a curved surface (spherical surface, free curved surface, etc.), it is deformed into a form along those surfaces. It is impossible to attach it by letting it.

On the other hand, although the conductive fabric described in Patent Document 2 can be adapted to a spherical surface or a free curved surface, the thickness of each conductive cloth is changed by pressing, and the distance between the conductive threads is shortened, so that the conductive fabric is static. Since it utilizes the phenomenon that the capacitance changes in the direction of increasing, it is necessary to compose the entire fabric with conductive threads, and the amount of conductive threads used increases as the detection area expands (the area increases). This can lead to an increase in size and complexity of the structure, which can be a factor directly linked to an increase in cost.

As a result of diligent research, the present inventor can deal with a detection area having a relatively large area even though it has a simple structure, and the detection area can be a flat surface as well as a curved surface. We have come up with an applicable capacitive touch sensor.

That is, the capacitive touch sensor according to the present invention has a conductive metal sheet that functions as a counter electrode and a detection electrode that is provided at a position close to the metal sheet and electrically insulated from the metal sheet. And a capacitance type detection circuit that is electrically connected to the detection electrode and has a current detection unit, and a power supply that supplies power to the capacitance type detection circuit, and is between the metal sheet and the object to be detected. The feature is that the current detection unit detects the total value of the first capacitance, which is the capacitance of the above, and the second capacitance, which is the capacitance between the metal sheet and the detection electrode. It is said.

In the process of developing a new touch sensor performed by the present inventor, when the detection electrode is provided at a position close to the metal sheet and the metal sheet functions as a counter electrode, the detection electrode is located between the metal sheet and the detection electrode. It was found that the capacitance is not significantly affected by the size of the area of the metal sheet. Focusing on this phenomenon, the present inventor pays attention to this phenomenon, and is the first capacitance which is the capacitance between the metal sheet and the object to be detected by the current detection unit of the capacitance type detection circuit electrically connected to the detection electrode. By adopting a novel configuration that has never been conceived before, it detects the total value of the capacitance and the second capacitance, which is the capacitance between the metal sheet and the detection electrode. It has been found that it is possible to identify whether the object to be detected is in contact with or close to the metal sheet based on the total value.

As described above, according to the capacitive touch sensor according to the present invention, even when the area of the metal sheet functioning as the counter electrode is set to a relatively large size, the object to be detected is generated with respect to the metal sheet. It is possible to detect contact or approach. Therefore, according to the present invention, even when it is desired to secure a detection area having a relatively large area, it is possible to increase the size of the detection area by setting the size of the metal sheet according to the size of the detection area. For example, as compared with the case where the detection area is increased by the conductive woven fabric in which the entire fabric is composed of the conductive thread, the structure is not complicated due to the increase in the detectable area, and a significant cost increase is avoided. be able to.

In particular, according to the capacitive touch sensor according to the present invention, the metal sheet as the counter electrode is made of a thin and flexible material (material) to set the detection region (the touch sensor according to the present invention). It is possible to configure a touch sensor that can be arranged (mounted) not only on a flat flat surface but also on a curved surface or an irregularly undulating surface depending on the application location). Therefore, the capacitive touch sensor according to the present invention is a bed leaving sensor that can be laid under the duvet cover to detect the user getting out of bed, and a seating sensor that can be laid under the cushion cover to detect the user's sitting. It can be used as various touch sensors. Further, for example, by covering the metal sheet with a cloth cover, for example, the appearance is improved as compared with the configuration in which the metal sheet is exposed, and the metal sheet is prevented from being damaged or soiled. It can be suitably used in situations where it is difficult to recognize the type touch sensor as a sensor. When the metal sheet as the counter electrode is formed into a conductive thin film sheet, it is preferable to form the metal sheet with, for example, aluminum foil.

In particular, if the capacitive touch sensor according to the present invention has a shape-retaining sheet attached to the metal sheet as a backing material, the shape of the metal sheet can be maintained and is made of metal. It is possible to prevent / suppress damage to the sheet. A PET sheet can be mentioned as a suitable example of the backing material.

If the capacitive touch sensor according to the present invention has an information output unit that communicates or notifies the detection information detected by the current detection unit to the outside, the user or the like can use the output information from the information output unit ( It is possible to grasp and identify the contact or approach of the object to be detected to the metal sheet by utilizing the detection information detected by the current detection unit), and it is possible to take actions and measures to be taken based on the output information. Is.

According to the present invention, it is possible to secure a detection electrode that is lightweight and has a relatively large area while having a simple structure, and is applied not only when the detection region is a flat flat surface but also when it is a curved surface. It is possible to provide a highly versatile capacitive touch sensor that can be used in various applications.

The schematic diagram of the capacitive touch sensor which concerns on one Embodiment of this invention. The principle diagram of the capacitive touch sensor which concerns on the same embodiment. The schematic diagram which shows the application example of the capacitive touch sensor which concerns on the same embodiment. The schematic diagram which shows the water level measuring meter using the capacitive touch sensor which concerns on the same embodiment. Principle diagram of a conventional capacitive touch sensor.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the capacitance type touch sensor 1 according to the present embodiment includes a conductive metal sheet 2 that functions as a counter electrode and a detection electrode 3 provided at a position close to the metal sheet 2. A capacitance type detection circuit 4 electrically connected to the detection electrode 3 and a power supply 5 for supplying power to the capacitance type detection circuit 4 are provided.

The metal sheet 2 is formed of a thin and flexible material such as aluminum foil, and is set to an appropriate size (for example, a large area of about 700 mm × 700 mm) according to the application. FIG. 1 schematically shows a rectangular thin metal sheet 2. By addressing the metal sheet 2 with, for example, a PET shape-retaining sheet having the same shape as the metal sheet 2 as a backing material (not shown), the shape of the metal sheet 2 can be maintained. The metal sheet 2 can be used as it is in an exposed form, but it is used in a form in which the entire surface or at least the front surface is covered with an appropriate cover 6 (in the illustrated example, only the front surface is covered). be able to. The cover 6 is inseparably attached to the metal sheet 2 with an appropriate adhesive or adhesive such as an adhesive tape. The cover 6 is made of a material that does not adversely affect the conductivity of the metal sheet 2. By appropriately selecting the color and material of the cover 6, it is possible to tailor the design (giving a texture, etc.) according to the application, installation location, etc. of the capacitive touch sensor 1 and to make it feel good. Further, by covering at least the front surface of the metal sheet 2 with the cover 6, it is possible to make the design difficult to notice as a sensor.

The detection electrode 3 is provided at a position close to the metal sheet 2 and is electrically insulated from the metal sheet 2. In the present embodiment, as shown in FIG. 2, the front surface of the substrate on which the capacitance type detection circuit 4 is mounted is set as the detection electrode 3, and the detection electrode 3 faces the back surface of the metal sheet 2. It is arranged in a (parallel posture). The insulating property of the detection electrode 3 with respect to the metal sheet 2 is ensured by interposing an insulating material such as an insulating tape between the detection electrode 3 and the metal sheet 2. As shown in FIG. 1, the entire detection electrode 3 overlaps the metal sheet 2, and the detection electrode 3 cannot be visually recognized from the front surface of the metal sheet 2. As shown in FIG. 2, which will be described later, detection is performed. A configuration in which a part of the electrode 3 overlaps the metal sheet 2 can be adopted.

The capacitance type detection circuit 4 is configured by using a plurality of circuit elements (not shown) mounted on the back surface of the substrate whose front surface is set on the detection electrode 3. The capacitance type detection circuit 4 has, for example, a current detection unit 41 including a current-voltage converter. Here, as shown in FIG. 2, the capacitance type detection circuit 4 can be regarded as a circuit constituting the discharge system 40 having the current detection unit 41.

The power supply 5 may be any as long as it has a power supply function, and can be configured by using, for example, the mobile battery shown in FIG.

Here, when the power supply 5 is regarded as the charging system 50, the capacitive touch sensor 1 of the present embodiment has the charging system 50 and the discharging system 40 with respect to the detection electrode 3 as shown in FIG. It has a switch 42 that alternately switches at a predetermined switching frequency. This switch 42 is naturally included in the capacitance type detection circuit 4.

The capacitance type touch sensor 1 according to the present embodiment has a first capacitance Cs1 which is a capacitance between the metal sheet 2 and the object to be detected H, a metal sheet 2 and a detection electrode 3. The current detection unit 41 is configured to detect the total value Cs of the second capacitance Cs2, which is the capacitance between the two. The present inventor has a capacitance between the metal sheet 2 and the detection electrode 3 (second capacitance Cs2) even when the size (area) of the metal sheet 2 functioning as the counter electrode is increased. As a result of verification, we have obtained that there is almost no change.

Therefore, the total value Cs detected by the current detection unit 41 clearly reflects the increase / decrease in the first capacitance Cs1, which is the capacitance between the metal sheet 2 and the object H to be detected. When the total value Cs detected by the current detection unit 41 is a value equal to or higher than a predetermined threshold value, it is possible to detect an event in which the object to be detected H is in contact with or in close proximity to the metal sheet 2.

The capacitive touch sensor 1 according to the present embodiment includes an information output unit 7 that communicates or notifies the detection information detected by the current detection unit 41 to the outside (see FIG. 2). The information output unit 7 may be incorporated in the same substrate as the capacitance type detection circuit 4, or may be composed of parts separate from the parts constituting the capacitance type detection circuit 4. Is. The information output method / mode by the information output unit 7 can be appropriately selected and set according to the application of the capacitive touch sensor 1.

An application example of the capacitive touch sensor 1 according to the present embodiment will be described below.
For example, when the capacitive touch sensor 1 according to the present embodiment is used in the fields of medical care and nursing care, as shown in FIG. 3, the mattress F and pillow M of the bed B, the handrail T and the boarding / alighting portion of the bed B The floor Y of each of the above is set as a detection area by the capacitance type touch sensor 1, and each detection of the capacitance type touch sensor 1 in which the size of the metal sheet 2 is appropriately set according to the size and shape of the detection area and the like. Set in the area (the mode of setting is mounting, mounting, pasting, mounting, etc.). The capacitive touch sensor 1 is set in a state of being covered from above with a pillow cover, mattress sheets, a handrail cover, a flooring mat, etc. (a state in which the user cannot see it or a state in which the user does not directly touch it). You can also do it.

When the capacitance type touch sensor 1 according to the present embodiment is used in such an application, the detection value detected by the current detection unit 41 (the total value Cs of the first capacitance Cs1 and the second capacitance Cs2) can be obtained. Based on this, it is possible to detect that a patient, a person to be cared for, or the like is close to the metal sheet 2 of the capacitive touch sensor 1.

As described above, the thin and lightweight capacitive touch sensor 1 according to the present embodiment can detect whether or not the patient or the care target person is in a predetermined bed B or is lying on the bed B. Functions as a bed leaving sensor. Moreover, since many of the conventional bed leaving sensors use a pressure switch having a convex shape of about 20 to 30 mm, there is a high possibility that the patient will recognize the bed leaving sensor and feel uncomfortable. According to the capacitive touch sensor 1 according to the embodiment, a patient or a care target is provided by a cover 6 that covers the entire metal sheet 2 or the front surface, or a sheet that covers the capacitive touch sensor 1 from above. It is possible to secure a situation in which it is difficult for a person or the like to intuitively recognize the existence of the capacitive touch sensor 1, and excessive stress, anxiety, or discomfort such as "being monitored" or "an object is hitting the body". Can be used as a bed leaving sensor that does not give to patients or care recipients.

Further, as shown in FIG. 3, when the output information from the information output unit 7 of each capacitive touch sensor 1 is set to be receivable by the common controller C by wireless communication, the capacitive touch sensor Although an individual controller is not required for each, a person in a position of monitoring and managing a patient or a person to be cared for can grasp the detection information by each capacitive touch sensor 1 without omission. It is also possible to set the output information from the information output unit 7 of each capacitive touch sensor 1 so that it can be received by a device such as a smartphone or tablet.

As another application example of the capacitive touch sensor according to the present embodiment, for example, by setting the capacitive touch sensor directly on the seat surface of the chair or under the seat cover covering the seat surface, the chair can be set. Capacitive touch sensor that can be used as a seating sensor that can detect whether a person is sitting, or in a relatively wide area in the height direction including the place where the open / close switch is placed in the automatic door of a building or vehicle. By setting, it can be mentioned that it can be used as an open / close switch for an automatic door that can be touched even by a short child.

Furthermore, by setting a capacitive touch sensor in a predetermined area on the floor in a workplace such as a factory and stepping on the capacitive touch sensor when an abnormality occurs, an administrator or the like can detect the occurrence of an abnormality. Capacitive touch sensor can be used as a notification sensor that can notify the user, or a capacitive touch sensor can be set around the reception desk of a financial institution or the cash register of a store to provide a capacitive touch in the event of an abnormal situation such as robbery. By touching the sensor, it can be used as a notification sensor that can notify the administrator etc. of the occurrence of an abnormal situation. Furthermore, a capacitive touch sensor is set on the outer circumference of the safe, and a third other than the administrator. When a person or the like touches the safe, the capacitive touch sensor detects the event and uses the suspicious information as a notification sensor capable of notifying with a warning sound or an announcement.

Further, as shown in FIG. 4, the water level measuring meter X can be configured by using the capacitive touch sensor according to the present embodiment. The water level meter X includes two detection rods X1 and X2 having different lower end positions, and the capacitance type touch sensor 1 according to the present embodiment includes a predetermined region including the lower ends of the respective detection rods X1 and X2 (illustration example). Then, by setting it in the area covering the entire detection rod), one detection rod (first detection rod X1) functions as a detection rod for detecting the lower limit of the water level, and the other detection rod (second detection rod X2) functions as a water level. It functions as a detection rod for detecting the upper limit. The water level measuring meter X shown in FIG. 4 holds two linear detection rods X1 and X2 separated from each other by a predetermined distance by a common detection box X3, and the second detection rod X2 is about 100 mm high. It is set so that it can be slid in the vertical direction. According to such a water level measuring meter X, it is possible to detect whether or not the water level has reached a preset lower limit value by the first detection rod X1, and the water level is set to an upper limit preset by the second detection rod X2. It is possible to detect whether or not the value has been reached. The detection information of the first detection rod X1 and the second detection rod X2 is set so as to be able to communicate with a predetermined communication device by a common signal cable X4. As a suitable application place of such a water level measuring meter X, there can be a paddy field in which the introduction of a known expensive water level measuring meter X is likely to be postponed although the water level must be controlled.

The present invention is not limited to the above-described embodiment. For example, the metal sheet may be made of a material other than aluminum foil as long as it is conductive. The shape and size of the metal sheet can be changed as appropriate.

The communication means for outputting the detection information of the capacitive touch sensor according to the present invention to the output destination is not limited to wireless communication, and may be wired communication.

As a power source, a battery other than a mobile battery can be used, or a power supply by wiring can be used. It may be configured to use wireless power supply that transmits electric power wirelessly.

In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 ... Capacitive touch sensor 2 ... Metal sheet 3 ... Detection electrode 4 ... Capacitive detection circuit 41 ... Current detection unit 5 ... Power supply 7 ... Information output unit

Claims (3)

A conductive metal sheet that functions as a counter electrode,
A detection electrode provided at a position close to the metal sheet and electrically insulated from the metal sheet,
A capacitance type detection circuit that is electrically connected to the detection electrode and has a current detection unit,
It is equipped with a power supply that supplies power to the capacitance type detection circuit.
The total value of the first capacitance, which is the capacitance between the metal sheet and the object to be detected, and the second capacitance, which is the capacitance between the metal sheet and the detection electrode. A capacitive touch sensor characterized in that it is configured to be detected by the current detection unit. The capacitive touch sensor according to claim 1, wherein a shape-retaining sheet is attached to the metal sheet as a backing material. The capacitive touch sensor according to claim 1 or 2, further comprising an information output unit that communicates or notifies the detection information detected by the current detection unit to the outside.

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