JP2019211839A - Touch sensor device - Google Patents

Abstract

To provide a touch sensor device capable of reducing cost.SOLUTION: A touch sensor device 1 roughly comprises: a plurality of detection electrodes (first detection electrode 21 to fourth detection electrode 24) arranged on an arrangement surface 820 of an arrangement object, for detecting a detection object through capacitance generated between the detection object and itself; and a plurality of resistors (resistor 310 to resistor 340) having resistance values (resistance value Rto resistance value R) defined so as to compensate sensitivity depending on each curvature of the arrangement surface 820 on which the plurality of detection electrodes are arranged, and electrically connected to the plurality of detection electrodes, respectively.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a touch sensor device.

  As a conventional technique, a first electrode set in which a central electrode is disposed at a portion having a first curvature of a rim cross section when incorporated in a rim of a steering wheel, and a central electrode is disposed on a rim when incorporated in a rim. There is known a capacitance sensor including a second electrode set disposed in a portion having a second curvature smaller than the first curvature of a cross section (see, for example, Patent Document 1).

  The capacitance sensor includes a first electrode interval between the center electrode of the first electrode set and at least one of the first side electrode and the second side electrode of the first electrode set. More than the second electrode interval between the center electrode of the second electrode set when incorporated in the rim and at least one of the first side electrode and the second side electrode of the second electrode set It is arranged to be shorter. This electrostatic capacity sensor can accurately detect the grip of the driver's steering when it is incorporated into a rim that includes portions with different curvatures.

JP 2017-50238 A

  However, since the conventional capacitance sensor has three electrodes arranged according to the curvature, there is a problem that the number of electrodes increases and the size of the detection circuit increases and the cost increases as the steering shape becomes complicated. .

  Accordingly, an object of the present invention is to provide a touch sensor device that can reduce costs.

  According to one embodiment of the present invention, a plurality of detection electrodes that are arranged on a placement surface of a placement target and detect the detection target through capacitance generated between the detection targets and a placement surface on which the plurality of detection electrodes are arranged Provided is a touch sensor device including a plurality of resistors having resistance values determined so as to correct the sensitivity in accordance with respective curvatures and electrically connected to a plurality of detection electrodes.

  According to the present invention, cost can be suppressed.

FIG. 1A is a schematic view of steering of a vehicle in which an example of a touch sensor device according to an embodiment is arranged, and FIG. 1B is a diagram of I (b) of FIG. 1A of the touch sensor device. ) -I (b) is an example of a cross-sectional view of a cross section cut from the arrow direction. 2A is an example of a block diagram of the touch sensor device according to the embodiment, FIG. 2B is a schematic diagram illustrating an example of a measurement unit, and FIG. It is a graph which shows an example of the time change of the voltage in a circuit. FIG. 3 is a flowchart illustrating an example of the operation of the touch sensor device according to the embodiment.

(Summary of embodiment)
The touch sensor device according to the embodiment includes a plurality of detection electrodes that are arranged on the arrangement surface of the arrangement target and that detect the detection target via capacitance generated between the detection target and the plurality of detection electrodes. A plurality of resistors having a resistance value determined so as to correct the sensitivity according to the curvature of each of the arranged surfaces and electrically connected to each of the plurality of detection electrodes. .

  This touch sensor device corrects the sensitivity according to the curvature by connecting a resistance to the detection electrode, so the number of detection electrodes is reduced and detection is performed compared to the case where the sensitivity is corrected by changing the arrangement interval of the electrodes. The scale of the circuit is reduced and the cost can be suppressed.

[Embodiment]
(Outline of touch sensor device 1)
FIG. 1A is a schematic view of steering of a vehicle in which an example of a touch sensor device according to an embodiment is arranged, and FIG. 1B is a diagram of I (b) of FIG. 1A of the touch sensor device. ) -I (b) is an example of a cross-sectional view of a cross section cut from the arrow direction. 2A is an example of a block diagram of the touch sensor device according to the embodiment, FIG. 2B is a schematic diagram illustrating an example of a measurement unit, and FIG. It is a graph which shows an example of the time change of the voltage in a circuit. In FIG. 2C, the horizontal axis is time t and the vertical axis is voltage V.

  In each figure according to the embodiment described below, the ratio between figures may be different from the actual ratio. In FIG. 2A, the flow of main signals and information is indicated by arrows.

  For example, as shown in FIGS. 1A and 1B, the touch sensor device 1 is arranged on the arrangement surface 820 of the arrangement target, and detects the detection target via the capacitance generated between the touch sensor device 1 and the detection target. A plurality of detection electrodes to be detected and a resistance value determined to correct the sensitivity in accordance with the curvature of each of the arrangement surfaces 820 on which the plurality of detection electrodes are arranged, and each of the plurality of detection electrodes is electrically And a plurality of connected resistors.

  The arrangement target of the present embodiment is, for example, a gripping portion 81 of the steering wheel 8 of the vehicle gripped by the driver as shown in FIG. The touch sensor device 1 is schematically configured to detect gripping with respect to the gripping portion 81. As a modification, the touch sensor device 1 is not limited to this, and may be configured to detect gripping with respect to an arrangement target such as a column.

The touch sensor device 1 outputs, for example, grasping information S ₅ to be described later shows the presence of grip on the grip portion 81 to the connected electronic equipment. As an example, this electronic device is an automatic driving control device that controls automatic driving of a vehicle. For example, the automatic driving control device determines whether to switch from automatic driving to manual driving or whether to switch from manual driving to automatic driving based on whether the steering wheel 8 is gripped.

  As an example, the plurality of detection electrodes are a first detection electrode 21 to a fourth detection electrode 24 as shown in FIG. Further, as an example, the plurality of resistors are a resistor 310 to a resistor 340 as shown in FIG. In the touch sensor device 1, for example, the detection electrode unit 2 is configured by the first detection electrode 21 to the fourth detection electrode 24.

  The touch sensor device 1 includes, for example, as shown in FIG. 2A, a voltage measurement unit 3 that measures the voltage by charging and discharging the detection electrode, and a capacitance acquired through the detection electrode and the resistance, A control unit 4 is provided as a determination unit that compares a predetermined threshold value 40 and determines the detection of the detection target.

  For example, as shown in FIG. 1A, the steering 8 includes a horn, an airbag, and the like, and includes a base portion 80 that supports the grip portion 81 and a grip portion 81 having a ring shape. The grip 81 is provided with a grip 83 made of resin or leather.

  In FIG. 1B, the left side is the driver's seat side, and the right side is the front side of the vehicle. For example, as shown in FIG. 1B, the gripping portion 81 has a constant curvature of the surface of the core portion 82 of the gripping portion 81 and varies depending on the location. The surface of the core portion 82 is an arrangement surface 820 on which the first detection electrode 21 to the fourth detection electrode 24 are arranged. For example, the arrangement surface 820 mainly has four curvatures (first curvature portion 820a to fourth curvature portion 820d).

  The core portion 82 is made of, for example, a metal core formed of a metal material such as iron or aluminum, and a resin material such as urethane formed around the metal core. For example, as shown in FIG. 1B, the core portion 82 has a driver seat side curvature smaller than the front curvature. And the grip part 81 differs in the curvature between a driver's seat side and the front side from others. For example, as shown in FIG. 1A, the core 82 has a large curvature because the little finger of the driver's index finger contacts the front side of the gripping portion 81, and the thumb and its base contact the driver's seat side. Therefore, the shape is easy to grip with a small curvature.

  The driver seat side is, for example, a fourth curvature portion 820d shown in FIG. The front side is, for example, the second curvature portion 820b. And the upper part and lower part which connect a driver's seat side and the front side are the 1st curvature part 820a and the 3rd curvature part 820c.

The curvatures of the first curvature portion 820a to the fourth curvature portion 820d are, for example, κ _{1 to} κ ₄ . As an example, the curvature is κ ₄ <κ ₂ <κ ₁ = κ ₃ .

(Configuration of detection electrode unit 2)
The first detection electrode 21 to the fourth detection electrode 24 are, for example, formed on a cloth or a soft sheet with the gap 20 interposed therebetween as shown in FIG. For example, when the first detection electrode 21 to the fourth detection electrode 24 are formed on a sheet, they are formed as a thin metal film having conductivity such as copper. For example, when the first detection electrode 21 to the fourth detection electrode 24 are formed on a cloth, the first detection electrode 21 to the fourth detection electrode 24 may be formed by sewing a conductive thread on the cloth, or conductive on the cloth. The cloth which has property may be sewn.

  The first detection electrode 21 to the fourth detection electrode 24 have, for example, an elongated shape so as to be arranged in the circumferential direction of the gripping portion 81 as shown in FIGS. 1 (a) and 1 (b). doing. In addition, the 1st detection electrode 21-the 4th detection electrode 24 are not the shape connected in ring shape but the shape which notched partially, for example, as shown to Fig.1 (a).

  In addition, the first detection electrode 21 to the fourth detection electrode 24 are arranged, for example, around a position where tangents of surfaces having different curvatures at the arrangement surface 820 have the same angle.

  For example, as shown in FIGS. 2A and 2B, the first detection electrode 21 is electrically connected to a resistor 310. Similarly, the second detection electrode 22 to the fourth detection electrode 24 are electrically connected to resistors 320 to 340 as shown in FIG. 2A, for example.

As an example, the resistance values of the resistors 310 to 340 are R _{1 to} R ₄ . The resistance values (R _{1 to} R ₄ ) are made equal in ratio to the curvature for each of the plurality of detection electrodes so that the sensitivity is corrected according to the respective curvatures (κ _{1 to} κ ₄ ). In other words, the ratio between the resistance value (R _{1 to} R ₄ ) and the curvature (κ _{1 to} κ ₄ ) is made equal for each of the plurality of detection electrodes. That is, R ₁ / κ ₁ , R ₂ / κ ₂ , R ₃ / κ ₃ , and R ₄ / κ ₄ are made equal. Therefore, the resistance value is set so that R ₁ : R ₂ : R ₃ : R ₄ = κ ₁ : κ ₂ : κ ₃ : κ ₄ holds.

  Where the curvature is low, the contact area during gripping tends to increase. Further, in a place where the curvature is high, the contact area during gripping tends to be small. Therefore, in order to make the sensitivity in a place with a large curvature close to the sensitivity in a place with a low curvature, correction is performed by reducing or increasing the voltage signal output from the detection electrode.

Here, when the driver grips the grip portion 81, a capacitance C is generated between the driver and the detection electrode. In the CR series circuit of the capacitance C and the combined resistance value R of the detection electrode and the resistor, for example, as shown in FIG. 2C, when the voltage V has a small product of CR (CR ₁ ), the rise is quick. Large (CR ₂ ) is known to slow down. This product is called the time constant τ. This time constant τ is a measurable value. Here, the time constant tau, for example, as shown in FIG. 2 (c), is measured as the time until 0.63V ₀ to the reference voltage V ₀ to be charged.

The time constant τ is a product of CR as described above. In order to measure the capacitance C formed between the driver's hand and the detection electrode, it can be calculated if the time constant τ and the resistance value R are known. Therefore, the resistance values R ₁ to R ₄ are set larger than the resistance values of the first detection electrode 21 to the fourth detection electrode 24.

When the driver grips the grip portion 81, a resistance value R is generated by combining a resistance value proportional to the length of the detection electrode up to the contacted position and a resistance value set according to the curvature. The resistance value set according to the curvature is a predetermined resistance value as described above, and does not change before and after gripping. However, the resistance value proportional to the length of the detection electrode up to the contacted position changes in proportion to the gripped position. The touch sensor device 1 does not need to detect the position where the grip portion 81 is gripped. Since the resistance value proportional to the length is preferably small enough not to contribute to the combined resistance R, the resistance value (maximum value R _m ) of the detection electrode is the resistance value R ₁ of the resistors 310 to 340 according to the curvature. It is smaller than - the resistance value _{R 4.} For example, the resistance values are determined so that R ₁ + R _m ≈R ₁ , R ₂ + R _m ≈R ₂ , R ₃ + R _m ≈R ₃ , and R ₄ + R _m ≈R ₄ .

Therefore, the capacitance C is calculated by using the resistance value R ₁ to the resistance value R ₄ of the resistor 310 as the resistance value and measuring the time constant τ regardless of where the driver grips the grip portion 81. Done.

(Configuration of voltage measuring unit 3)
For example, as shown in FIG. 2A, the voltage measurement unit 3 is electrically connected to the first measurement unit 31 to the fourth detection electrode 24 that are electrically connected to the first detection electrode 21. In addition, a fourth measuring unit 34 is provided. The voltage measuring unit 3 is schematically configured to charge / discharge the first detection electrode 21 to the fourth detection electrode 24.

  FIG. 2B shows an example of the first measurement unit 31. The second measurement unit 32 to the fourth measurement unit 24 are different in resistance from the first measurement unit 31, but the other configurations are the same, so the first measurement unit 31 will be described.

For example, the first measurement unit 31 includes a switch SW ₁₁ as shown in FIG. The terminal 31 a of the first measurement unit 31 is connected to the first detection electrode 21 and to the resistor 310 and the voltage measurement terminal VSW ₁₁ .

The reference voltage V ₀ is applied to the terminal a ₁₂ of the switch SW ₁₁ . The terminal a ₁₃ of the switch SW ₁₁ is connected to GND (ground). Terminal _{a 11} of the switch _{SW 11} is, for example, an analog switch which is connected to any pin of the terminal _{a 12} or terminal _{a 13.} A resistor 310 is connected between the terminal a ₁₁ and the voltage measurement terminal VSW ₁₁ . For example, the switch SW ₁₁ is subjected to switching control based on the control of the control unit 4.

The first measurement unit 31 connects the terminal a ₁₁ and the terminal a ₁₂ of the switch SW ₁₁ to charge the first detection electrode 21 and measures the voltage via the voltage measurement terminal VSW ₁₁ . The measured voltage, for example, is output to the control unit 4 as a voltage signal S _1.

The first measuring unit 31 connects the terminal a ₁₁ and the terminal a ₁₃ of the switch SW ₁₁ and discharges the charge accumulated in the first detection electrode 21. The 1st measurement part 31 performs this charge and discharge periodically.

Similarly, the second measurement unit 32 to the fourth measurement unit 34 measure the voltage and output the voltage signal S ₂ to the voltage signal S ₄ to the control unit 4. The control unit 4 determines gripping according to the charging / discharging and discharging cycles.

(Configuration of control unit 4)
The control unit 4 includes, for example, a CPU (Central Processing Unit) that performs operations and processes on acquired data according to a stored program, a RAM (Random Access Memory) that is a semiconductor memory, a ROM (Read Only Memory), and the like. Microcomputer. In this ROM, for example, a program for operating the control unit 4 and a threshold value 40 are stored. The RAM is used as a storage area for temporarily storing calculation results and the like, for example. The control unit 4 has means for generating a clock signal therein, and measures time based on the clock signal.

The control unit 4 is configured to calculate the capacitance C based on the time constant τ and the resistance value R. Specifically, when the voltage signal S _{1 of} the first detection electrode 21 is input from the voltage measurement unit 3, the control unit 4 measures the time until it becomes 0.63 V ₀ and obtains the time constant τ ₁ . Subsequently, the control unit 4 detects the capacitance C ₁ (= τ ₁ /) detected by the first detection electrode 21 based on the resistance value R ₁ of the resistor 310 connected to the first detection electrode 21 and the time constant τ _1. R ₁ ) is calculated.

Further, when the voltage signal S _{2 of} the second detection electrode 22 is input from the voltage measurement unit 3, the control unit 4 measures the time until it becomes 0.63 V ₀ and obtains the time constant τ ₂ . Subsequently, the controller 4 detects the capacitance C ₂ (= τ ₂ //) detected by the second detection electrode 22 based on the resistance value R ₂ of the resistor 320 connected to the second detection electrode 22 and the time constant τ _2. R ₂ ) is calculated.

In addition, when the voltage signal S _{3 of} the third detection electrode 23 is input from the voltage measurement unit 3, the control unit 4 measures the time until it becomes 0.63 V ₀ and obtains the time constant τ ₃ . Subsequently, the control unit 4 detects the capacitance C ₃ (= τ ₃ /) detected by the third detection electrode 23 based on the resistance value R ₃ of the resistor 330 connected to the third detection electrode 23 and the time constant τ _3. R ₃ ) is calculated.

Further, when the voltage signal S _{4 of} the fourth detection electrode 24 is input from the voltage measurement unit 3, the control unit 4 measures the time until it becomes 0.63 V ₀ and obtains the time constant τ ₄ . Subsequently, the controller 4 detects the electrostatic capacitance C ₄ (= τ ₄ //) detected by the fourth detection electrode 24 based on the resistance value R ₄ of the resistor 340 connected to the fourth detection electrode 24 and the time constant τ _4. R ₄ ) is calculated.

The control unit 4 calculates the capacitances C ₁ to C ₄ in parallel. Then, the control unit 4 compares the calculated capacitances C ₁ to C ₄ with the threshold value 40. The control unit 4, if a plurality of the electrostatic capacitance of the capacitance C _{1 ~} capacitance C ₄ is the threshold value 40 or more, it is determined that the grip portion 81 is gripped, the gripping information S ₅ showing a grasping Output.

  Below, an example of operation | movement of the touch sensor apparatus 1 of this Embodiment is demonstrated according to the flowchart of FIG.

(Operation)
The control unit 4 of the touch sensor device 1 monitors the voltage signal S ₁ to the voltage signal S ₄ input via the voltage measurement unit 3 and obtains the time constant τ ₁ to the time constant τ ₄ . Subsequently, the control unit 4 calculates capacitances C ₁ to C ₄ based on the calculated time constants τ ₁ to τ ₄ and resistance values R ₁ to R ₄ (Step 1). ).

Next, the control unit 4 compares the calculated capacitances C ₁ to C ₄ with the threshold value 40. The control unit 4, a plurality of capacitance if it was the threshold value 40 or more (Step2: Yes), determines that there gripping outputs the gripping information S ₅ indicating the gripped connected electronic equipment ( Step 3).

  Here, in Step 2, when the plurality of capacitances are smaller than the threshold value 40 (Step 2: No), the control unit 4 advances the processing to Step 1 in order to calculate the capacitance of the next cycle.

(Effect of embodiment)
The touch sensor device 1 according to the present embodiment can reduce the cost. Specifically, since the touch sensor device 1 corrects the sensitivity according to the curvature by connecting a resistor to the detection electrode, the number of detection electrodes is compared with the case where the sensitivity is corrected by changing the arrangement interval of the electrodes. And the size of the detection circuit is reduced, and the cost can be suppressed.

  The touch sensor device 1 can correct the sensitivity by suppressing the number of electrodes and the size of the detection circuit even if the touch sensor device 1 is an object to be arranged with a nonuniform curvature.

  Here, as another embodiment, the touch sensor device 1 is schematically configured to detect gripping of the left hand 90 and the right hand 91, for example, as shown in FIG. Specifically, the touch sensor device 1 is configured such that the first detection electrode 21 to the fourth detection electrode 24 are divided into two at the center of the grip portion 81 and detect left side grip and right side grip. Is done. Therefore, the touch sensor device 1 of this embodiment can detect gripping with both hands.

  As mentioned above, although some embodiment and modification of this invention were demonstrated, these embodiment and modification are only examples, and do not limit the invention based on a claim. These novel embodiments and modifications can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the scope of the present invention. In addition, not all combinations of features described in these embodiments and modifications are necessarily essential to the means for solving the problems of the invention. Furthermore, these embodiments and modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Touch sensor apparatus, 2 ... Detection electrode part, 3 ... Voltage measurement part, 4 ... Control part, 8 ... Steering, 20 ... Clearance, 21-24 ... 1st detection electrode-4th detection electrode, 31-34 ... 1st measurement part-4th measurement part, 40 ... Threshold value, 80 ... Base part, 81 ... Gripping part, 82 ... Core part, 83 ... Grip, 90 ... Left hand, 91 ... Right hand, 310-340 ... Resistance , 820 ... Arrangement surface, 820a to 820d ... 1st curvature part to 4th curvature part

Claims (4)

A plurality of detection electrodes that are arranged on the arrangement surface of the arrangement target and detect the detection target via capacitance generated between the detection target;
A plurality of resistors having resistance values determined so as to correct sensitivity according to respective curvatures of the arrangement surface on which the plurality of detection electrodes are arranged, and electrically connected to the plurality of detection electrodes When,
A touch sensor device. The resistance value is equal to the ratio of the curvature for each of the plurality of detection electrodes so that the sensitivity is corrected according to each curvature.
The touch sensor device according to claim 1. The arrangement target is a grip portion of a steering wheel of a vehicle gripped by a driver.
The touch sensor device according to claim 1. A determination unit that determines the detection of the detection target by comparing the capacitance acquired through the detection electrode and the resistor with a predetermined threshold;
The touch sensor device according to claim 1.

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