JP2008141329A - Capacitance type touch switch device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a configuration of a switch electrode of an electrode pattern of an electrode sheet of a capacitance type touch switch device used as an input method, capable of reducing of malfunction if cold water is poured on a switch panel front surface and water drop is made, without using a special structure and a special circuit. <P>SOLUTION: The capacitance version touch switch comprises a panel switch 1 and a control portion. At the panel switch 1, an electrode film is printed with a pattern where a switch electrode required for switching operation of ON/OFF and an electrode arranged around the switch electrode for sensing if a conductor substance such as cold water is attached are disposed, and the electrode film is pasted onto a glass pane or an acrylic board by adhesives or a double-sided tape. The control portion, comprising capacitance variation measuring portion, is connected to the electrode pattern of the panel switch 1, and detects variation in capacitance of the panel switch. When a conductor substance such as cold water is attached, it is judged whether regular ON/OFF operation or malfunction by cold water etc. occurs according to variance in capacitance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitive touch switch device that employs a capacitive method as an input method.

The conventional capacitive touch switch device shown in FIG. 1 includes a panel switch 1 and a control board 2. The panel switch is an electrode sheet obtained by printing a silver paste on a PET film 9 as shown in FIGS. 2 and 3, and is adhered to a dielectric 7 made of acrylic or glass with an adhesive 8 (double-sided tape or the like). Composed.
When the finger 10 (conducting member) approaches the panel switch shown in FIG. 4, a parallel plate capacitor in which a dielectric is sandwiched between the electrode and the finger is formed, and the capacitance increases. Conversely, when the finger is separated from the panel switch, the capacitance formed as a parallel plate capacitor with the dielectric sandwiched between the electrode and the finger decreases.
The control board 2 shown in FIG. 1 converts this change in capacitance into a voltage by a C / V (capacitance is voltage) conversion circuit, and an analog / digital converter (ADC) provided in an arithmetic processing unit (CPU). The general operation principle of the capacitive touch switch is to determine the ON / OFF state of the switch based on a control program that determines the operation of the arithmetic processing unit by replacing it with digital data.
However, as shown in FIG. 5, when water is applied to the surface of the panel switch and water droplets are formed, the water is also conductive, so that when the finger (conductive member) approaches, the capacitance increases. This may cause malfunction.
Japanese Patent No. 2887336

  FIG. 2 shows an electrode sheet of a conventional capacitive touch switch device. The wiring pattern 4 and the GND pattern 5 are connected to the control unit via the switch electrode 4 and the connector connection terminal, and are created by printing the above pattern with a silver base on a PET film or the like. As shown in the cross-sectional view of the panel switch in FIG. 3, the electrode sheet is used as a panel switch (operation plate) by being attached to a dielectric 7 (glass plate, resin, etc.) with an adhesive 8 or a double-sided tape. Since the capacitance changes when the switch electrode 4 is touched with a finger, it can be used for an ON / OFF operation as a switch if it is satisfied with the threshold stored in the CPU. When the water droplet 12 smaller than the switch electrode is attached to the switch electrode 4 of the panel switch as shown in FIG. 6, the change in capacitance is smaller than when touched with a finger. However, if the switch electrode 4 is larger than the switch electrode 4 as in the case of the water droplet 13, the change in the capacitance becomes large, so that it cannot be distinguished from the operation touched by the finger. In addition, when a plurality of switch electrodes (water droplets) are attached to a plurality of switch electrodes like the water droplet 14, each switch electrode can be distinguished from a normal operation because the change in capacitance is small. When the switch electrode is touched, the capacitance of the plurality of switch electrodes with water greatly changes due to the conductivity of the water, and the plurality of switches enter at the same time (turn on). There is a possibility of malfunction.

  Therefore, in the conventional method, when water droplets are attached to the surface of the panel switch, a capacitance change occurs, and when a capacitance change similar to the state in which a finger touches the panel switch occurs, Each of the electrodes functions as a switch, and ON information is transmitted to the switch-equipped device. Depending on the switch, for example, if it is a cooking device, the ignition switch is ignited arbitrarily, or if it is a washing machine, the operation of the washing machine If it is a stop switch, malfunctions unintended by humans such as stopping on the way will occur.

  Therefore, as a measure to prevent malfunction due to water on the panel switch, the surface of the panel switch is inclined so that water droplets on the surface of the panel switch can flow quickly. At present, water repellent treatment is applied. However, even when the surface of the panel switch is tilted, an instantaneous capacitance change occurs when water drops flow over the electrode part of the panel switch, and the panel switch is turned on and the water drops pass on the panel switch electrode. When there is no water droplet on the electrode, it is turned off, and malfunction cannot be prevented. In addition, a projection is provided on the surface of the electrode part of the panel switch, and it is effective for electrodes with a small area arranged on the panel switch. As a result, the capacitance of the panel switch changes, preventing malfunction. In addition, there is a problem that the panel switch shape is limited due to provision of unnecessary slopes and protrusions, and the versatility is poor and difficult to use.

  In the present invention, a control board provided with a CPU, a film connected to the control board, a switch electrode necessary for ON / OFF switch operation on the film, and the film attached to a dielectric, the switch electrode The change in capacity when a conductive substance adheres to the periphery of the CPU is transmitted to the CPU and compared with a threshold value stored in the CPU to determine whether the normal switch is ON, OFF, or malfunctioning. Therefore, the present invention proposes a capacitive touch switch device provided with an electrode film on which a pattern in which switch electrodes are provided is printed.

  Since it is configured only by changing the electrode pattern of the electrode sheet of the panel switch section, it is not necessary to incline the panel switch or to provide a protrusion on the part corresponding to the switch electrode of the panel switch, so the degree of freedom in design It is possible to reduce malfunction due to water or the like without increasing the cost of parts by adding a special structure or circuit.

  The details of the present invention will be described with reference to the accompanying drawings. FIG. 8 shows an example of an electrode sheet. When the switch electrode 18 is touched with a normal finger, the change in capacitance is compared with a threshold value stored in advance in the CPU of the control board 16 in FIG. Consider the electrode to make a decision. A switch electrode 19 is separately provided around the switch electrode 18.

  The switch electrode 19 is an electrode for observing a change in capacitance of a dielectric such as water. With this configuration, a change in electrostatic capacitance of the switch electrode 18 and the switch electrode 19 is combined to determine an operation touched by a finger and a malfunction caused by a dielectric due to water or the like. That is, when the change in the capacitance of the switch electrode 18 satisfies the threshold value and no change in the capacitance of the switch electrode 19 is recognized, it can be determined that the operation is performed with a finger. If the switch electrode 18 is larger than the switch electrode 18 such as the water droplet 20, the change in the capacitance of the switch electrode 18 satisfies the threshold value, but the change in the capacitance of the switch electrode 19 is recognized even if the amount is small. It can be judged that a conductor such as is attached.

  In the case where the switch electrodes 18 such as the water droplets 21 extend over the plurality of switch electrodes 18, the area attached to each switch electrode is small, and in this state, the change in capacitance is small and the threshold value is not satisfied. When touched, the capacitance of the plurality of switch electrodes 18 changes greatly at the same time because water or the like is conductive. Even in this case, since the electrostatic capacity of the switch electrode 19 is changed by the water droplet 21, it can be determined that a conductive substance is attached. By observing the change in the capacitance of the switch electrode 19 in this way, in a product with a monitor, etc., it is possible to urge the user to be careful about wiping off the water on the panel switch (operation panel). .

Structure diagram of capacitive touch switch device Electrode sheet Panel switch cross section When the panel switch is touched with a finger When water drops on the panel switch Electrode sheet Structure diagram of capacitive touch switch device Electrode sheet

Explanation of symbols

1 Panel switch 2 Control board 3 Connector connection terminal 4 Switch electrode 5 GND
6 Wiring Pattern 7 Dielectric 8 Adhesive 9 PET Film 10 Finger 11 Water Drop 12 Water Drop 13 Water Drop
14 Water Drop 15 Panel Switch 16 Control Board 17 Connector Connection Terminal 18 Switch Electrode 19 Switch Electrode 20 Water Drop 21 Water Drop

Claims (1)

A control board provided with a CPU, a film connected to the control board, a switch electrode necessary for ON / OFF switch operation on the film, and the film is attached to a dielectric, and conductive around the switch electrode. It is provided to send a change in capacity when a substance with a property adheres to the CPU and compare it with a threshold value stored in the CPU to judge whether the switch is normal ON, OFF, or malfunction. An electrostatic capacitance type touch switch device comprising an electrode film on which a pattern in which switch electrodes are arranged is printed.

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