JP6898771B2 - Touch sensor - Google Patents

Description

The present invention relates to a touch sensor used in a music player, a home electric appliance, a mobile device, a computer device, an information communication device, an automobile-mounted device, and the like.

There are various types of capacitive sensors, one of which is a type that uses a slidable slider (see Patent Documents 1 and 2). Although not shown in this type, a plurality of detection electrodes for detecting capacitance are arranged, and the detection result of each detection electrode is calculated to detect the position of a dielectric such as a finger by a detection circuit. .. The number of the plurality of detection electrodes is increased from the viewpoint of improving the detection accuracy when the detection of the position of a dielectric such as a finger is required over a long distance, for example, a distance of 80 mm.

Japanese Unexamined Patent Publication No. 2012-008049 Japanese Unexamined Patent Publication No. 2012-255681

Since the conventional capacitance type sensor is configured as described above, in order to detect the position of the dielectric with high accuracy over a long distance, a large number of detection electrodes must be arranged. Along with this, there is a problem that the detection circuit also needs to be increased. In order to solve this problem, a switching means for switching the input of the detection circuit may be adopted from the viewpoint of reducing the number of detection circuits, but this complicates the circuit and increases the manufacturing cost. New problems will arise.

The present invention has been made in view of the above, and an object of the present invention is to provide a touch sensor capable of reducing the number of detection circuits, preventing circuit complications, and reducing manufacturing costs.

In the present invention, in order to solve the above problems, an AC voltage is applied to the conductive detection wire rod that is approached to the dielectric via an insulating operation protection layer, the form-maintaining member for the conductive detection wire rod, and the conductive detection wire rod. The application means, the conductive detection wire, and the detection determination means connected to the application means are provided.
The form-maintaining member is formed into an insulating tubular shape, and the conductive detection wire is wound around the outer peripheral surface in a coil shape in the axial direction at a predetermined pitch, and the conductive detection wire and the conductive detection wire adjacent to each other are wound. An air layer is interposed between the two, and it is installed in close proximity with the outer peripheral surface facing below the operation protection layer.
When the dielectric and the conductive detection wire are close to each other and the inductance value and the impedance value are changed, the detection determination means is at least when the dielectric and the conductive detection wire are close to each other among these inductance values and impedance values. It is characterized in that an impedance value is detected and the approach of a dielectric is determined using this impedance value.

Here, examples of the dielectric in the claims include at least a dedicated writing instrument, a finger, and the like. Further, as the conductive detection wire, at least a wire in which the conductive wire is coated with an insulating material, a wire or band in which the fluid conductive material is hardened, a flexible resin sheet (for example, PET, etc.) is plated with a metal foil. , A circuit sheet or the like in which a circuit is formed of an inorganic substance such as ITO.

The form-maintaining member can be formed into a tubular shape by using a resin, a resin sheet, a resin film, or the like. The form-maintaining member does not particularly ask whether or not it is flexible or elastic. Further, the detection determination means can compare the impedance value or the inductance value before and after the change with the threshold value.

According to the present invention, when an AC voltage is applied to the conductive detection wire and then the dielectric approaches the conductive detection wire, the parasitic capacitance between the wound conductive detection wires increases, and the inductance value and the impedance value change, respectively. To do. By detecting at least the impedance value of the changed inductance value and the impedance value, it is possible to determine that the dielectric has approached the conductive detection wire and to specify the approaching position.

According to the present invention, since a parasitic capacitance can be generated between the adjacent conductive detection wire and the conductive detection wire, the detection electrode function can be easily improved by increasing the number of windings of the conductive detection wire. it can. Further, it is possible to eliminate the need to increase the number of detection and determination means and to adopt the switching means for input switching. Therefore, the circuit configuration can be simplified, and the manufacturing cost can be expected to be reduced. Further, since the conductive detection wire is wound around the shape maintaining member in a coil shape to prevent the shape from collapsing, the wound state of the conductive detection wire can be maintained for a long period of time. Further, since the conductive detection wire becomes a solenoid coil, a parasitic capacitance can be formed between the wound conductive detection wires, and if a dielectric is brought close to the solenoid coil, the parasitic capacitance between the conductive detection wires of the solenoid coil can be formed. Can be increased to make the inductance value and the impedance value small.

It is an overall explanatory view which shows typically the embodiment of the touch sensor which concerns on this invention. It is a circuit block diagram which shows typically the equivalent circuit of the solenoid coil in embodiment of the touch sensor which concerns on this invention. It is an overall explanatory view which shows typically the 2nd Embodiment of the touch sensor which concerns on this invention. It is a plane explanatory view which shows typically the 3rd Embodiment of the touch sensor which concerns on this invention. It is explanatory drawing which shows typically the solenoid coil in the Example of the touch sensor which concerns on this invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the touch sensor in the present embodiment includes a conductive detection line 2 approaching a finger 1 which is a dielectric and the conductive detection line 2. A form-maintaining member 10 for the conductive detection line 2, an AC power supply as an application means for applying an AC voltage to the conductive detection line 2, and a detection determination circuit 20 connected to the conductive detection line 2 and the AC power supply are provided. When 1 and the conductive detection line 2 come close to each other and the inductance value and the impedance value change, at least the impedance value when the finger 1 and the conductive detection line 2 come close to each other is detected.

For the conductive detection wire 2, for example, a coated electric wire in which a copper wire is covered with an insulating enamel is used, and the conductive detection wire 2 is wound around a form-maintaining member 10. The conductive detection wire 2 is not particularly limited, and may be a coated electric wire in which a copper alloy wire is covered with enamel, a coated electric wire in which an aluminum wire is covered with enamel, or the like. Further, as the conductive detection wire 2, instead of enamel, an insulating polyurethane resin, polyester resin, polyamide-imide resin or the like is used as needed.

The form-maintaining member 10 is formed into a thin and small cylindrical pipe using, for example, an insulating resin, and is fixedly installed below the insulating operation protection layer 11, and the operation protection layer 11 is decorated. The finger 1 comes into contact with the surface and is operated. The resin of the form-maintaining member 10 is not particularly limited, but for example, polyester-based, polypropylene-based, polyethylene resin, polyvinyl chloride resin, polyethylene terephthalate resin, polycarbonate resin, polyamide resin, polyimide resin, phenol resin, and glass. Examples thereof include fiber-impregnated epoxy resin and acrylic resin. Among these, polyethylene terephthalate resin and polycarbonate resin having excellent dimensional stability and insulating properties are preferable.

In the form-maintaining member 10, the conductive detection lines 2 are space-wound in a coil shape in the axial direction at predetermined equal intervals on the outer peripheral surface thereof, and the space is wound between the conductive detection lines 2 and the adjacent conductive detection lines 2. The air layer 3 is interposed in the air layer 3. Such a conductive detection wire 2 is wound in a coil shape to form a cylindrical solenoid coil 4, and is wound by an AC voltage to be wound between the adjacent conductive detection wire 2 and the conductive detection wire 2. In addition, a parasitic capacitance (stray capacitance) of the capacitor component is generated. This parasitic capacitance has a feature that the shorter the distance between the adjacent conductive detection lines 2, the larger the parasitic capacitance.

The detection / determination circuit 20 is composed of, for example, a microcomputer or the like, and a predetermined history or the like is stored in the RAM, a predetermined program is stored in the ROM, and the predetermined program is rewritten as necessary by the control controller. The detection determination circuit 20 is connected to both ends of the conductive detection line 2 and automatically detects at least the impedance value among the inductance value and the impedance value.

Such a detection determination circuit 20 realizes a predetermined function as a computer by reading a predetermined program stored in the ROM with the RAM area as a work area, and contributes to the control of a device equipped with a touch sensor. Function. That is, the detection determination circuit 20 has a function of constantly comparing the impedance value with a preset threshold value, and a function of determining that the finger 1 is in a non-approaching state when the compared impedance value is equal to or greater than the threshold value. When the compared impedance value is less than the threshold value, the function of determining that the finger 1 is in the approaching state is realized.

Next, the operating principle of the touch sensor will be described. Generally, the solenoid coil 4 has not only the pure inductance L but also the resistance R of the conductive detection line 2 itself and the parasitic capacitance C between the adjacent conductive detection lines 2. Therefore, the equivalent circuit shown in FIG. 2 is configured. When the finger 1 is brought into contact with the solenoid coil 4 after applying an AC voltage, the finger 1 acts as an inductor and the parasitic capacitance increases. Therefore, the change in the current flowing through the solenoid coil 4 and the solenoid coil 4 As the voltage at both ends changes, the inductance and impedance values decrease. Therefore, if at least the impedance value after the contact of the finger 1 is detected, it can be used as a touch sensor.

In the above configuration, when the finger 1 comes into contact with a predetermined position on the surface of the operation protection layer 11 after applying an AC voltage to the conduction detection line 2, the conduction detection line 2 located directly below the finger 1 and the predetermined position of the operation protection layer 11 As a result, the parasitic capacitance between the conductive detection lines 2 located directly below the predetermined location of the operation protection layer 11 increases, the inductance value and the impedance value change and become smaller, and the impedance value changes and is detected. It is output to the determination circuit 20.

The detection determination circuit 20 compares the impedance value before the change with the preset threshold value, and when the changed impedance value is output, the impedance value after the change is compared with the preset threshold value. .. As a result of the comparison, since the impedance value after the change is less than the threshold value, it is determined with high accuracy that the finger 1 has touched a predetermined position on the surface of the operation protection layer 11, and by this determination, a predetermined device equipped with the touch sensor is determined. A function, such as a temperature control function, is performed.

According to the above configuration, a parasitic capacitance can be generated between the adjacent conductive detection wire 2 and the conductive detection wire 2. Therefore, if the number of windings of the conductive detection wire 2 is increased, the conventional detection electrode function can be easily obtained. It can be improved. Further, it is possible to eliminate the need to increase the number of detection determination circuits 20 and to adopt a switching means for input switching. Therefore, the circuit configuration can be simplified, and the manufacturing cost can be greatly reduced. Further, instead of simply winding the conductive detection wire 2 in a coil shape, the conductive detection wire 2 is wound around the shape maintaining member 10 in a coil shape to prevent the shape from collapsing, so that the conductive detection wire 2 is wound. The coiled state can be maintained for a long period of time.

Next, FIG. 3 shows a second embodiment of the present invention. In this case, when the conductive detection wire 2 is wound around the outer peripheral surface of the form maintaining member 10 in a coil shape to form a solenoid coil 4. The winding pitches of the conductive detection wires 2 are not all equalized, but are partially changed to increase or decrease the amount of change in the parasitic capacitance.

When the conductive detection wire 2 is wound around the outer peripheral surface of one end (left side in FIG. 3) of the shape maintaining member 10, the conductive detection wire 2 is space-wound at a winding pitch narrower than the normal reference pitch, and is wound in a space at the center of the shape maintaining member 10. When it is wound around the outer peripheral surface of the portion, it is space-wound at a normal reference pitch, and when it is wound around the other end (right side in FIG. 3) of the form maintaining member 10, it is normally wound. Space winding is performed with a winding pitch wider than the reference pitch.

Such a conductive detection wire 2 has a large parasitic capacitance on one end side of the form maintaining member 10 and a small parasitic capacitance on the other end side of the form maintaining member 10. Further, when the finger 1 is brought close to one end side of the form maintaining member 10, the central portion of the form maintaining member 10, or the other end side of the form maintaining member 10, even if the facing areas of the fingers 1 are the same, the parasitic capacitance The value of the increase will be different. Since the other parts are the same as those in the above embodiment, the description thereof will be omitted.

In this embodiment as well, the same effects as those in the above embodiment can be expected, and the finger 1 is placed on one end side of the form maintaining member 10, the central portion of the form maintaining member 10, or the other end side of the form maintaining member 10. Since the inductance value and the impedance value are different when they are brought close to each other, it is clear that the approaching position of the finger 1 can be easily specified from the inductance value and the impedance value.

Further, if the winding pitch of the conductive detection wire 2 is gradually changed to gradually increase or decrease the amount of change in the parasitic capacitance, the correlation between the contact position of the finger 1 and the inductance value and the impedance value is established. Since it occurs, the temperature, volume, and the like can be adjusted by operating the slider by shifting the finger 1 in contact with the surface of the operation protection layer 11 (see the arrow in FIG. 3).

Next, FIG. 4 shows a third embodiment of the present invention. In this case, the conductive detection line 2 is not formed on the three-dimensional cylindrical solenoid coil 4, but the shape is maintained in a substantially plate shape. A pattern is formed on the surface of the member 10A in a spiral shape having a substantially elliptical plane.
The conductive detection wire 2 may be formed by winding a coated electric wire in a spiral shape having a substantially elliptical plane and then adhering it to the surface of the form maintaining member 10A. It may be screen-printed and cured, coated and cured, or etched to form a pattern.

The fluid conductive material is not particularly limited, and examples thereof include conductive pastes, carbon nanotubes, carbon nanofibers, conductive polymers, and ITO. Further, the winding pitches of the conductive detection wires 2 are basically equal intervals, but when it is desired to generate large and small parasitic capacitances, one side portion 5 has a narrow pitch that causes a large change in parasitic capacitances. The other side portion 6 has a wide pitch that causes a small change in parasitic capacitance.

The form-maintaining member 10A is formed of a thin plate having at least a flat surface on the front and back surfaces, and an operation protection layer 11 with which the finger 1 comes into contact is installed above the front and back surfaces. A plurality of operation buttons 12 located above the detection line 2 are formed at intervals. When the winding pitches of the conductive detection lines 2 of the plurality of operation buttons 12 are different, at least one operation button 13 is located directly above one side portion 5 of the conductive detection line 2, and the other operation buttons 14 are the conductive detection lines 2. It is located directly above the other side portion 6. Since the other parts are the same as those in the above embodiment, the description thereof will be omitted.

In this embodiment as well, the same action and effect as those in the above embodiment can be expected, and moreover, when the operation button 13 is touched with the finger, the operation button 14 is touched with the finger, or the operation button 12 is not touched with the finger. In this case, since the inductance value and the impedance value are different from each other, it is clear that the approaching position of the finger 1 can be easily specified from the inductance value and the impedance value. Further, since the conductive detection line 2 is formed in a low pattern on the surface of the form maintaining member 10A, it is clear that the touch sensor can be made thinner and space can be saved without being bulky.

In the above embodiment, the coated electric wire is wound around the form maintaining member 10 as the conductive detection wire 2, but the present invention is not limited to this. For example, a long circuit sheet in which a circuit is formed of a flexible resin sheet (for example, PET sheet) by an inorganic substance such as metal foil, plating, or ITO may be wound at a predetermined pitch. Further, a long circuit sheet may be formed in a substantially spiral pattern on the surface of the substantially plate-shaped form maintaining member 10A.

Further, in the above embodiment, the detection determination circuit 20 detects the impedance value, but the inductance value may be detected, or both the inductance value and the impedance value may be detected. When detecting the inductance value, the detection determination circuit 20 has a function of constantly comparing the inductance value with a preset threshold value, and when the compared inductance value is equal to or more than the threshold value, the finger 1 is in a non-approaching state. When the compared inductance value is less than the threshold value, the function of determining that the finger 1 is in an approaching state can be realized.

Further, the detection determination circuit 20 has a function of converting an impedance value or an inductance value into a detection value, a function of constantly comparing the detection value with a preset threshold value, and a case where the compared detection value is equal to or more than the threshold value. Can realize a function of determining that the finger 1 is in the non-approaching state and a function of determining that the finger 1 is in the approaching state when the compared detection value is less than the threshold value.

Hereinafter, an embodiment of the touch sensor according to the present invention will be described. As shown in FIG. 5, the form-maintaining member is formed into a cylindrical pipe made of vinyl chloride resin, and a conductive detection line is formed on the outer peripheral surface of the form-maintaining member. A cylindrical solenoid coil was formed by winding the coil in a coil shape in the axial direction at a predetermined equidistant pitch.
The outer diameter of the pipe was φ76 mm. The conductive detection wire was an enamel-coated copper wire having a wire diameter of 0.55 mm, and was space-wound 35 times. The solenoid coil was set to a length of 35 mm.

After forming a cylindrical solenoid coil, connect an LCR meter (manufactured by HIOKI, trade name IM3536) to this solenoid coil, and then apply an AC voltage of 2MHz / 0.25V to both ends of the solenoid coil to determine the inductance value and impedance. The value and was measured. As a result of measurement, the inductance value was 98 μH and the impedance value was 1.23 kΩ.

Then, a finger was brought into contact with the surface of the solenoid coil, and the inductance value and the impedance value were measured again. As a result of measurement, the inductance value was 92 μH and the impedance value was 1.17 kΩ.
From the above measurement results, it was confirmed that a touch sensor can be obtained by applying an AC voltage to the solenoid coil and using at least one of the inductance value and the impedance value.

The touch sensor according to the present invention is used in the manufacturing field of music players, home appliances, mobile devices, computer devices, information communication devices, automobile-mounted devices, and the like.

1 finger (dielectric)
2 Conductive detection wire (conductive detection wire)
3 Air layer 4 Solenoid coil 10 Form maintenance member 10A Form maintenance member 11 Operation protection layer 12 Operation button 13 Operation button 14 Operation button 20 Detection judgment circuit (detection judgment means)

Claims (1)

A conductive detection wire that is approached to a dielectric via an insulating operation protection layer, a form-maintaining member for the conductive detection wire, an application means for applying an AC voltage to the conductive detection wire, and a conductive detection wire and an application means. Equipped with a detection and determination means connected to
The form-maintaining member is formed into an insulating tubular shape, and the conductive detection wire is wound around the outer peripheral surface in a coil shape in the axial direction at a predetermined pitch. An air layer is interposed between the two, and it is installed in close proximity with the outer peripheral surface facing below the operation protection layer.
When the dielectric and the conductive detection wire are close to each other and the inductance value and the impedance value are changed, the detection determination means is at least when the dielectric and the conductive detection wire are close to each other among these inductance values and impedance values. A touch sensor characterized in that it detects an impedance value and uses this impedance value to determine the approach of a dielectric.

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