JP2020113960A - Detection device - Google Patents

Abstract

To detect a disconnection related to a shield electrode or a sensor electrode in an input device capable of performing cancel control.SOLUTION: A detection device includes a detection unit that detects disconnection of a sensor electrode to which a drive signal is applied or a shield electrode that reduces parasitic capacitance between the sensor electrode and a reference potential point in an input device that includes the sensor electrode and the shield electrode and performs control for applying the drive signal to the sensor electrode, and cancel control for applying a signal having the same waveform as the drive signal to the shield electrode, and the detection unit detects disconnection of the shield electrode or the sensor electrode on the basis of the capacitance of the shield electrode detected during the disconnection detection scan in which control for applying the drive signal to the shield electrode, and control for applying a signal having the same waveform as the drive signal to the sensor electrode are performed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a detection device.

Techniques have been developed to prevent erroneous operation determinations in capacitive input devices. Examples of the technique include the technique described in Patent Document 1.

JP, 2018-37348, A

An electrostatic capacitance type input device detects, for example, an electrostatic capacitance of an electrode corresponding to an electrostatic sensor (electrostatic switch), and detects a change in the electrostatic capacitance of the electrode caused by an operation by an operating body such as a finger. By doing so, it is determined whether or not the electrostatic sensor corresponding to the electrode is being operated. The change in the capacitance of the electrode is detected, for example, by comparing the detected capacitance of the electrode with a predetermined threshold value.

In an electrostatic capacitance type input device, a parasitic capacitance is generated between an electrode whose capacitance is to be detected (hereinafter referred to as “sensor electrode”) and a reference potential point (ground). The size of the parasitic capacitance generated between the sensor electrode and the reference potential point depends on the area of the sensor electrode and the like.

Since the parasitic capacitance generated between the sensor electrode and the reference potential point may become noise in the determination of the operation on the electrostatic sensor corresponding to the sensor electrode, the parasitic capacitance generated between the sensor electrode and the reference potential point is large. As a result, SNR (Signal-to-Noise Ratio) characteristics are disadvantageous. Therefore, in order to improve the detection accuracy of the operation with respect to the electrostatic sensor and prevent the erroneous determination of the operation, it is desirable to further reduce the parasitic capacitance generated between the sensor electrode and the reference potential point.

Here, for example, the input device described in Patent Document 1 includes a sensor electrode and a cancel electrode (hereinafter, also referred to as a shield electrode). The sensor electrode is an electrode to which a drive signal (voltage signal) for detecting the operation is applied, and the shield electrode is an electrode for reducing the parasitic capacitance between the sensor electrode and the reference potential point. In the input device described in Patent Document 1, control for applying a drive signal to the sensor electrode and cancellation control for applying a signal (voltage signal) having the same waveform as the drive signal to the shield electrode are performed.

When a drive signal is applied to the sensor electrode and a signal having the same waveform as the drive signal is applied to the shield electrode, the sensor electrode and the shield electrode have the same potential. Therefore, in the above case, no parasitic capacitance is generated between the sensor electrode and the shield electrode. Therefore, when a signal having the same waveform as the drive signal is applied to the shield electrode when the drive signal is applied to the sensor electrode, for example, parasitic capacitance between the sensor electrode and the reference potential point is reduced. It becomes possible to reduce.

Therefore, in the electrostatic capacitance type input device that performs the cancellation control like the input device described in Patent Document 1, there is an effect that “the operation detection accuracy can be improved and erroneous determination of the operation can be prevented”. Played.

However, if the signal having the same waveform as the drive signal cannot be applied to the shield electrode due to disconnection, cancel control cannot be performed. In this case, cancel control can be performed. Such an input device cannot achieve the above effects. In the following, the disconnection in the signal line for applying the signal having the same waveform as the drive signal to the shield electrode is referred to as “disconnection related to the shield electrode”. In addition, the disconnection in the signal line for applying the drive signal to the sensor electrode is referred to as “disconnection related to the sensor electrode”.

An object of the present invention is to provide a new and improved detection device capable of detecting a wire breakage of a shield electrode or a sensor electrode in an input device capable of canceling control.

In order to solve the above problems, according to an aspect of the present invention, a sensor electrode to which a drive signal is applied, and a shield electrode for reducing a parasitic capacitance between the sensor electrode and a reference potential point are provided. The shield electrode or the sensor electrode in an input device in which control for applying the drive signal to the sensor electrode and cancellation control for applying a signal having the same waveform as the drive signal to the shield electrode are performed. And a control for applying the drive signal to the shield electrode and a signal having the same waveform as the drive signal for the sensor electrode. There is provided a detection device that detects a disconnection of the shield electrode or the sensor electrode based on the capacitance of the shield electrode detected during the disconnection detection scan.

Further, the detection unit may detect that the shield electrode is disconnected when the electrostatic capacitance of the shield electrode detected during the disconnection detection scan is smaller than a predetermined value.

Further, the detection unit may detect that the sensor electrode is disconnected when the electrostatic capacitance of the shield electrode detected during the disconnection detection scan is larger than a predetermined value.

Further, the detection unit may control a switching circuit that switches application of a signal to the sensor electrode and the shield electrode.

As described above, according to the present invention, it is possible to detect the disconnection of the shield electrode or the sensor electrode in the input device capable of performing the cancel control.

It is a block diagram which shows the structure of the conventional detection apparatus. It is a figure which shows the structure of the detection apparatus at the time of performing the shield disconnection detection scan which concerns on one Embodiment of this invention. It is a figure which shows the structure of the detection apparatus 10 at the time of performing the touch detection scan which concerns on the same embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals, and duplicate description is omitted.

<1. Conventional configuration>
First, conventional touch operation detection and cancellation control will be described. FIG. 1 is a block diagram showing a configuration of a conventional detection device 90. As shown in FIG. 1, the conventional detection device 90 includes, for example, a capacitance detection unit 910, a sensor electrode 920, a shield electrode 930, a core metal 940, and an operational amplifier 950.

(Capacitance detection unit 910)
The electrostatic capacitance detection unit 910 detects whether or not a touch operation is performed by the user by detecting the electrostatic capacitance of the sensor electrode 920 and detecting a change in the electrostatic capacitance caused by an operation by an operation body such as a finger. To judge.

(Sensor electrode 920)
The sensor electrode 920 is an electrode to which a drive signal (voltage signal) for detecting a touch operation is applied.

(Shield electrode 930)
The shield electrode 930 is an electrode for reducing the parasitic capacitance between the sensor electrode 920 and the reference potential point. When cancel control is performed, a signal having the same waveform as the drive signal applied to the sensor electrode 920 is applied to the shield electrode 930.

(Core bar 940)
The core metal 940 functions as a ground.

(Op Amp 950)
The operational amplifier 950 applies a signal having the same potential and low impedance as the sensor electrode 920, between the sensor electrode 920 and the core metal 940, that is, the shield electrode 930.

The configuration of the conventional detection device 90 has been described above. With such a configuration, it is possible to cancel a large parasitic capacitance between the sensor electrode 920 and the cored bar 940 by applying a signal having the same waveform as the drive signal to the shield electrode 930 using the operational amplifier 950.

However, in the above configuration, when the signal line for applying the signal to the shield electrode 930 is disconnected, whether the change in the electrostatic capacitance detected by the electrostatic capacitance detection unit 910 is due to the touch operation or the above disconnection. I can't tell if it's a thing. For this reason, in the conventional detection device 90, when the disconnection related to the shield electrode 930 occurs, the touch operation may be erroneously determined. Therefore, a configuration capable of reliably separating the touch operation and the disconnection is required. To be

<2. Embodiment>
Next, the configuration of the detection device 10 according to the embodiment of the present invention will be described. FIG. 2 is a diagram showing the configuration of the detection device 10 when the shield disconnection detection scan according to the present embodiment is executed. As shown in FIG. 2, the detection device 10 according to the present embodiment includes a capacitance detection unit 110, a sensor electrode 120, a shield electrode 130, a core metal 140, an operational amplifier 150, and switching circuits 160a to 160d. Note that the sensor electrode 120, the shield electrode 130, the core bar 140, and the operational amplifier 150 may have substantially the same configurations as the above-described sensor electrode 920, shield electrode 930, core metal 940, and operational amplifier 950, respectively, and thus will be described in detail. Detailed description is omitted.

(Capacitance detection unit 110)
The electrostatic capacitance detection unit 110 according to the present embodiment detects the electrostatic capacitance of the sensor electrode 120 and detects the change in the electrostatic capacitance of the electrode caused by the operation of the operation body such as a finger, thereby performing a touch operation by the user. Is performed.

In addition, the electrostatic capacitance detection unit 110 according to the present embodiment detects a disconnection related to the shield electrode 130 or the sensor electrode 120 based on the electrostatic capacitance of the shield electrode 130 detected during the disconnection detection scan. One

Here, the disconnection detection scan according to the present embodiment refers to control for driving the sensor electrode 120 as a shield and detecting the capacitance of the shield electrode 130. That is, in the disconnection detection scan according to the present embodiment, control for applying a drive signal to the shield electrode 130 and control for applying a signal having the same waveform as the drive signal to the sensor electrode 120 are performed.

The disconnection detection scan according to the present embodiment is realized by switching the switching circuits 160a to 160d. In the case of the example shown in FIG. 2, by turning on the switching circuits 160a and 160c and turning off the switching circuits 160b and 160d, a drive signal is applied to the shield electrode 130, and a signal having the same waveform as the drive signal is applied to the sensor electrode. Applied to 120.

As described above, the capacitance detection unit 110 according to the present embodiment can switch the application of signals to the sensor electrode 120 and the shield electrode 130 by controlling the switching circuits 160a to 160d.

According to the disconnection detection scan by the electrostatic capacitance detection unit 110 according to the present embodiment, the electrostatic capacitance between the shield electrode 130 and the cored bar 140 can be accurately measured even when a touch operation is performed on the sensor electrode 120. Can be measured.

At this time, the electrostatic capacitance detection unit 110 according to the present embodiment can determine the disconnection of the sensor electrode 120 or the disconnection of the shield electrode 130 by comparing the detected electrostatic capacitance with a predetermined value. Is.

For example, when disconnection of the sensor electrode 120 occurs, the electrostatic capacitance detected during the disconnection detection scan is the electrostatic capacitance (predetermined value) detected when the disconnection of the sensor electrode 120 or the shield electrode 130 does not occur. ) Will be increased.

Therefore, in the electrostatic capacitance detection unit 110 according to the present embodiment, when the electrostatic capacitance of the shield electrode 130 detected during the disconnection detection scan is larger than a predetermined value, the disconnection of the sensor electrode 120 occurs. Can be detected.

On the other hand, when disconnection of the shield electrode 130 occurs, the electrostatic capacitance detected during the disconnection detection scan is the electrostatic capacitance (predetermined value) detected when the disconnection of the sensor electrode 120 or the shield electrode 130 does not occur. ) Will be less than.

Therefore, in the electrostatic capacitance detection unit 110 according to the present embodiment, when the electrostatic capacitance of the shield electrode 130 detected during the disconnection detection scan is smaller than a predetermined value, disconnection of the shield electrode 130 occurs. Can be detected.

As described above, in the disconnection detection scan according to the present embodiment, by driving the sensor electrode 120 as a shield, electrostatic discharge between the shield electrode 130 and the cored bar 140 is not affected by the sensor electrode 120. The capacity can be measured accurately.

According to such control, the disconnection of the sensor electrode 120 or the shield electrode 130 can be surely detected before the touch operation is determined, and the erroneous determination of the touch operation can be effectively prevented.

Note that the electrostatic capacitance detection unit 110 according to the present embodiment can switch to the touch detection scan for detecting the touch operation by the user by controlling the switching circuits 160a to 160d after the disconnection detection scan is completed. ..

FIG. 3 is a diagram showing the configuration of the detection device 10 when the touch detection scan according to the present embodiment is executed. As shown in FIG. 3, the electrostatic capacitance detection unit 110 according to the present embodiment switches to the touch detection scan by turning on the switching circuits 160b and 160d and turning off the switching circuits 160a and 160c.

In the touch detection scan according to the present embodiment, a drive signal is applied to the sensor electrode 120, and a signal having the same waveform as the drive signal is applied to the shield electrode 130. According to such control, the touch operation by the user can be detected by the change in the capacitance of the sensor electrode 120.

The functions of the electrostatic capacitance detection unit 110 according to this embodiment have been described above. The capacitance detection unit 110 according to the present embodiment may control the application of signals to the sensor electrode 120 and the shield electrode 130, in addition to the control described above.

The electrostatic capacitance detection unit 110 according to the present embodiment is realized by, for example, one or two or more processors configured of an arithmetic circuit such as a CPU (Central Processing Unit).

(Switching circuit 160)
The switching circuit 160 according to the present embodiment is configured to switch the application of signals to the sensor electrode 120 and the shield electrode 130 based on the control by the electrostatic capacitance detection unit 110.

The switching circuit 160 according to the present embodiment includes, for example, a switching transistor, and is in an ON state (conduction state) or an OFF state (non-conduction state) depending on the signal level (voltage level) of the applied signal.

Examples of the switching transistor include a bipolar transistor and an FET (Field-Effect Transistor) such as a TFT (Thin Film Transistor) and a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor).

The configuration of the detection device 10 according to the present embodiment has been described above. The configuration described above with reference to FIGS. 2 and 3 is merely an example, and the configuration of the detection device 10 according to the present embodiment is not limited to this example.

For example, in the above description, the case where the detection device 10 according to the present embodiment also serves as an input device has been described as an example, but the detection device 10 according to the present embodiment may be used as a shield electrode or a sensor electrode in an input device separately provided. It is also possible to detect such disconnection.

Further, for example, in the above, the case where the sensor electrode is single is described as an example, but the number of sensor electrodes according to the present embodiment is not limited to the example. Even when the input device includes a plurality of sensor electrodes, the capacitance detection unit 110 according to the present embodiment can detect disconnection of the plurality of sensor electrodes and the shield electrode.

Further, the disconnection detection scan according to the present embodiment may be executed at a frequency determined according to the specifications of the application on which the touch operation is performed. It is possible to reduce the possibility that the touch operation is erroneously determined as the disconnection detection scan is executed more frequently.

The detection device 10 according to the present embodiment is, for example, a vehicle such as a car (or a part of a vehicle system such as a UI (User Interface) portion that constitutes a vehicle system), a communication device such as a mobile phone or a smartphone, and a tablet type. Device, a computer such as a PC (Personal Computer), an ATM (Automated Teller Machine), and various other systems and devices including a capacitive input device.

<3. Summary>
As described above, the detection device 10 according to the embodiment of the present disclosure reduces the parasitic capacitance between the sensor electrode 120 to which the drive signal is applied and between the sensor electrode 120 and the reference potential point (core bar 140). In an input device that has a shield electrode 130 for causing the sensor electrode 120 to apply a drive signal and a cancel control that applies a signal having the same waveform as the drive signal to the shield electrode 130, A detection unit (capacitance detection unit 110) that detects a break in the shield electrode 130 or the sensor electrode 120 is provided.

The electrostatic capacitance detection unit 110 according to an embodiment of the present disclosure controls the shield electrode 130 to apply a drive signal and the sensor electrode 120 to apply a signal having the same waveform as the drive signal. One of the features is to detect the disconnection of the shield electrode 130 or the sensor electrode 120 based on the capacitance of the shield electrode 130 detected during the disconnection detection scan.

According to the above configuration, it is possible to detect the disconnection of the shield electrode or the sensor electrode in the input device capable of performing the cancel control.

The preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, but the present invention is not limited to these examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

Further, the effects described in the present specification are merely illustrative or exemplary, and are not limitative. That is, the technique according to the present disclosure may have other effects that are apparent to those skilled in the art from the description of the present specification, in addition to or instead of the above effects.

Further, it is possible to create a program for causing hardware such as a CPU, a ROM, and a RAM built in the computer to exhibit a function equivalent to the configuration of the detection device 10, and the program can be read by the computer. A non-transitory recording medium may also be provided.

10 detection device, 110 electrostatic capacitance detection part, 120 sensor electrode, 130 shield electrode, 140 core metal, 150 operational amplifier, 160 switching circuit

Claims (4)

A sensor electrode to which a drive signal is applied; and a shield electrode for reducing a parasitic capacitance between the sensor electrode and a reference potential point, the control for applying the drive signal to the sensor electrode, In an input device in which cancellation control for applying a signal having the same waveform as the drive signal to the shield electrode is performed, a detection unit that detects a disconnection related to the shield electrode or the sensor electrode,
Equipped with
The detection unit detects during a disconnection detection scan in which control for applying the drive signal to the shield electrode and control for applying a signal having the same waveform as the drive signal to the sensor electrode are performed. Based on the electrostatic capacitance of the shield electrode, to detect the disconnection of the shield electrode or the sensor electrode,
Detection device. When the capacitance of the shield electrode detected during the disconnection detection scan is smaller than a predetermined value, the detection unit detects that a disconnection has occurred in the shield electrode,
The detection device according to claim 1. When the capacitance of the shield electrode detected during the disconnection detection scan is higher than a predetermined value, the detection unit detects that a disconnection has occurred in the sensor electrode,
The detection device according to claim 1. The detection unit controls a switching circuit that switches application of a signal to the sensor electrode and the shield electrode,
The detection device according to claim 1.

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