JP2018060635A - Input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device capable of achieving improvement of high detection accuracy of operation by an operation body.SOLUTION: An input device includes: a switch part having a first electrode and a second electrode provided between the first electrode and a reference potential point; a detection part for detecting operation to the switch part on the basis of a change in electrostatic capacity of the first electrode; and a control part for executing a first control of applying a driving signal to the first electrode and applying a signal with the same waveform as the driving signal to the second electrode or a second control of connecting the first electrode with the reference potential point and applying the driving signal to the second electrode .SELECTED DRAWING: Figure 4

Description

  The present invention relates to an input device.

  A technique for improving detection accuracy in a capacitance sensor has been developed. As a technique related to a capacitive sensor including a guard electrode to which the same voltage as the voltage applied to the detection electrode is applied, for example, a technique described in Patent Document 1 is cited.

JP 2013-190404 A

  The capacitance type input device detects, for example, the capacitance of an electrode corresponding to an electrostatic sensor (electrostatic switch), and determines a change in the capacitance of the electrode caused by an operation with an operating body such as a finger. Thus, it is detected that an operation is performed on the electrostatic sensor corresponding to the electrode. The change in the capacitance of the electrode is determined, for example, by comparing the detected capacitance of the electrode with a predetermined threshold value.

  In the capacitance type input device, parasitic capacitance is generated between an electrode for detecting capacitance (hereinafter, referred to as “sensor electrode”) and a reference potential point (ground). Since the parasitic capacitance generated between the sensor electrode and the reference potential point can be a noise in the detection of the operation on the electrostatic sensor corresponding to the sensor electrode, the larger the parasitic capacitance, the SNR (Signal-to-Noise Ratio). It is disadvantageous in characteristics. Therefore, in order to improve the detection accuracy of the operation for the electrostatic sensor, it is desirable to reduce the parasitic capacitance generated between the sensor electrode and the reference potential point.

  Further, in the capacitance type input device, the capacitance of the sensor electrode may fluctuate due to factors other than the operating body such as temperature change and humidity change. When the capacitance of the sensor electrode fluctuates due to factors other than the operating body as described above, for example, “the operation with the operating body is not performed, but the electrostatic sensor corresponding to the sensor electrode “It is determined that the operation is being performed” or the like may occur. That is, when the capacitance of the sensor electrode fluctuates due to factors other than the operating body as described above, there is a possibility that erroneous operation detection may occur in the capacitance type input device.

  Here, for example, in addition to the sensor electrode (the detection electrode corresponds) as in the capacitive sensor described in Patent Document 1, an electrode separate from the sensor electrode (the guard electrode corresponds). ) Is provided with a capacitance type input device.

  When a drive signal (voltage signal) for detection is applied to the sensor electrode, a signal (voltage signal) having the same waveform as the drive signal is applied to the separate electrode. The electrode and the separate electrode have the same potential. Therefore, in the above case, the capacitance between the sensor electrode and the separate electrode is sufficiently small.

  Therefore, when a drive signal is applied to the sensor electrode, a signal having the same waveform as the drive signal is applied to the separate electrode, for example, between the sensor electrode and the reference potential point. It is possible to reduce the parasitic capacitance.

  Therefore, when a drive signal is applied to the sensor electrode and a signal having the same waveform as that of the drive signal is applied to the separate electrode, the detection accuracy of the capacitive input device is improved. There is an advantage that it is possible to achieve.

  Hereinafter, the separate electrode to which a signal having the same waveform as the drive signal applied to the sensor electrode is applied is referred to as a “cancel electrode”. Hereinafter, “control for applying a signal having the same waveform as the drive signal to the cancel electrode when the drive signal is applied to the sensor electrode” is referred to as “cancel control”.

  However, even if the cancel control is performed in the capacitance type input device, there is a case where the influence of the above-described variation in the capacitance of the sensor electrode cannot be sufficiently reduced. Therefore, even if the cancel control is performed, the above-described erroneous detection may occur in the capacitive input device.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved input device capable of improving the detection accuracy of an operation by an operating tool. There is.

  In order to achieve the above object, according to one aspect of the present invention, a first electrode, a switch unit having a second electrode provided between the first electrode and a reference potential point, and the first electrode A detection unit that detects an operation on the switch unit based on a change in capacitance of the switch, and a drive signal is applied to the first electrode based on a detection result of the operation, and the second electrode Control for performing first control for applying a signal having the same waveform as the drive signal, or for performing second control for connecting the first electrode to the reference potential point and applying the drive signal to the second electrode. An input device is provided.

  With this configuration, for example, the parasitic capacitance between the first electrode and the reference potential point is reduced by cancel control, and the variation in the capacitance of the first electrode due to the change in the external environment is corrected, and then the operation is performed. Detection can be performed. Therefore, with this configuration, it is possible to improve the detection accuracy of the operation by the operating tool, compared to the case where only the cancel control is performed.

  In addition, the first control is a control for detecting an operation on the switch unit, and the second control is for acquiring the amount of change in the capacitance of the first electrode other than the operation body. Control may also be used.

  The controller may perform the first control when the operation is not detected, and may alternately perform the first control and the second control after the operation is detected. Good.

  The controller may perform the second control every time a predetermined time elapses.

  In addition, the detection unit includes a capacitance of the first electrode when the operation is not detected and a capacitance of the first electrode at a plurality of times when the second control is performed. Based on the calculated amount of change, the amount of change in the capacitance of the first electrode due to other than the operating body is calculated, and when the amount of change is calculated, You may detect the operation with respect to the said switch part by correct | amending the change of the electrostatic capacitance of a 1st electrode.

  In addition, when the change amount is not calculated, the detection unit may detect an operation on the switch unit without correcting the change.

  In addition, when the second control is performed, the capacitance between the second electrode and the reference potential point is greater than the capacitance between the first electrode and the second electrode. However, it may be sufficiently small.

  According to the present invention, it is possible to improve the detection accuracy of the operation by the operating tool.

It is explanatory drawing which shows an example of the electrostatic capacitance of a sensor electrode in case cancellation control is performed in the input device which has a sensor electrode and a cancellation electrode. It is explanatory drawing which shows an example of the fluctuation | variation of the electrostatic capacitance of a sensor electrode by the change of the state of an operation body. It is explanatory drawing for demonstrating the 2nd control which concerns on embodiment of this invention. It is a block diagram which shows an example of a structure of the input device which concerns on embodiment of this invention.

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

  In the following description, an electrode that functions as a sensor electrode among the electrodes constituting the capacitive input device may be indicated as “sensor 1”. In the following description, an electrode that functions as a cancel electrode among the electrodes that constitute the capacitance-type input device may be referred to as “cancel 1”. Further, in the following, among the electrodes constituting the capacitance type input device, the electrode electrically connected to the reference potential point may be indicated as “GND1”.

[1] An example of a problem that may occur in a capacitance-type input device As described above, in a capacitance-type input device (hereinafter simply referred to as “input device”), cancel control is performed. It is possible to reduce the parasitic capacitance between the sensor electrode and the reference potential point.

  FIG. 1 is an explanatory diagram illustrating an example of a capacitance Cs of a sensor electrode when cancel control is performed in an input device having a sensor electrode and a cancel electrode.

  The capacitance Cs of the sensor electrode is, for example, the capacitance between the sensor electrode and the reference potential point GND. The capacitance Cs of the sensor electrode is represented by a combined capacitance of the capacitance Cp1 between the sensor electrode and the cancel electrode and the capacitance Cp2 between the cancel electrode and the reference potential point GND.

  By performing the cancel control, the capacitance Cp1 between the sensor electrode and the cancel electrode becomes sufficiently small. The capacitance Cs of the sensor electrode is a combined capacitance of the capacitance Cp1 and the capacitance Cp2. Therefore, by performing the cancel control, the input device can reduce the capacitance Cs of the sensor electrode.

  However, as described above, even if cancel control is performed, the influence of fluctuations in the capacitance Cs of the sensor electrode caused by factors other than the operating body such as temperature change and humidity change cannot be sufficiently reduced. There is.

  Here, in an input device in which cancel control is performed, an insulator such as a substrate using an insulator base material may exist between the sensor electrode and the cancel electrode and between the cancel electrode and the reference potential point. is there. When the insulator as described above is present, in the input device, for example, the relative permittivity of the insulator fluctuates due to a change in the external environment such as a change in temperature or a change in humidity. Variations occur. Here, as the fluctuation of the capacitance Cs of the sensor electrode caused by the fluctuation of the relative dielectric constant of the insulator, the fluctuation of the capacitance Cs of the sensor electrode and the fluctuation of the capacitance Cs of the sensor electrode are increased. Fluctuations are included.

  Therefore, in order to improve the detection accuracy of the operation by the operating body, the operation is detected after correcting the variation in the capacitance Cs of the sensor electrode due to the change in the external environment as described above. Is desirable.

  On the other hand, another factor that causes the capacitance Cs of the sensor electrode to fluctuate is “change in the state of the operating body such as a finger with respect to the sensor electrode”.

  FIG. 2 is an explanatory diagram illustrating an example of a change in the capacitance Cs of the sensor electrode due to a change in the state of the operating body. In FIG. 2, a finger of a user who performs an operation on the input device is shown as the operation body.

  As shown in FIG. 2, a capacitance Ct is generated between the operating body and the sensor electrode. Here, the capacitance Ct varies according to the state of the operating body with respect to the sensor electrode. Therefore, as shown in FIG. 2, the capacitance Cs of the sensor electrode varies according to the change in the capacitance Ct.

  As described above, factors that cause the capacitance Cs of the sensor electrode to fluctuate include a change in the external environment such as a temperature change or a change in the state of the operating body with respect to the sensor electrode.

  However, when an operation is performed on the sensor electrode corresponding to the electrostatic sensor, such as an operation in which the user touches the electrostatic sensor, a variation in the capacitance Cs of the sensor electrode, for example, as shown in Equation 1 below. However, it is difficult to determine whether it is due to a change in the state of the operating body with respect to the sensor electrode or a change in the external environment.

Here, “e _o ” shown in the following formula 1 is a vacuum dielectric constant, and “e _r ” shown in the following formula 1 is a relative dielectric constant. In addition, “S” shown in the following formula 1 is the area of the operating body and the like, and “d” shown in the following formula 1 is the distance between the operating body and the sensor electrode.

  In addition, as described above, it is difficult to identify the factors that cause fluctuations in the capacitance Cs of the sensor electrode. Therefore, the fluctuations in the capacitance Cs of the sensor electrode due to changes in the external environment may be corrected. It is also difficult.

[2] Outline of Input Device According to Embodiment of the Present Invention Accordingly, an input device according to an embodiment of the present invention includes a switch unit having a first electrode and a second electrode. The second electrode is provided between the first electrode and the reference potential point. The switch unit corresponds to an electrostatic sensor. An example of the configuration of the switch unit according to the embodiment of the present invention will be described later.

In addition, the input device according to the embodiment of the present invention performs the following first control or the following second control on the first electrode and the second electrode.
-First control: control for applying a drive signal to the first electrode and applying a signal having the same waveform as the drive signal to the second electrode-Second control: connecting the first electrode to a reference potential point Control to apply a drive signal to the second electrode

  The input device according to the embodiment of the present invention performs the first control or the second control based on the detection result of the operation on the switch unit. The input device according to the embodiment of the present invention performs the first control or the second control by switching between the first control and the second control based on the detection result of the operation on the switch unit. Switching between the first control and the second control in the input device according to the embodiment of the present invention will be described later.

[2-1] First Control The first control according to the embodiment of the present invention corresponds to cancel control.

  When 1st control is performed, the 1st electrode and 2nd electrode which comprise a switch part will be in the state shown in FIG. More specifically, when the first control is performed, “sensor 1” shown in FIG. 1 corresponds to the first electrode, and “cancel 1” shown in FIG. 1 corresponds to the second electrode.

That is, when the first control is performed, the first electrode and the second electrode function as follows.
・ First electrode: Sensor electrode ・ Second electrode: Cancel electrode

  Further, the capacitance Cp1 shown in FIG. 1 corresponds to the capacitance between the first electrode and the second electrode, and the capacitance Cp2 shown in FIG. 1 is between the second electrode and the reference potential point GND. It corresponds to the capacitance between. Hereinafter, the combined capacitance of the capacitance Cp1 and the capacitance Cp2 when the first control is performed may be referred to as “capacitance Cs of the first electrode”.

  As described above, there is an advantage that the detection accuracy in the input device can be improved by performing the cancel control. Therefore, in the input device according to the embodiment of the present invention, the first control is performed in order to detect an operation on the switch unit. That is, it can be said that the first control is control for detecting an operation on the switch unit.

  Therefore, the input device according to the embodiment of the present invention can improve detection accuracy in the input device by performing the first control.

[2-2] Second Control The second control according to the embodiment of the present invention is a control for acquiring the amount of change in the capacitance of the first electrode other than the operating body. Here, the amount of change in the capacitance of the first electrode due to other than the operating body according to the embodiment of the present invention corresponds to the amount of change in the capacitance of the first electrode due to a change in the external environment, as will be described later.

  FIG. 3 is an explanatory diagram for explaining the second control according to the embodiment of the present invention.

  When the second control is performed, the first electrode and the second electrode constituting the switch unit are in the state shown in FIG. More specifically, when the second control is performed, “GND1” shown in FIG. 3 corresponds to the first electrode, and “sensor 1” shown in FIG. 3 corresponds to the second electrode.

That is, when the second control is performed, the first electrode and the second electrode function as follows.
・ First electrode: Reference potential point ・ Second electrode: Sensor electrode

Also, the capacitance C _A of FIG. 3, corresponds to the capacitance between the first electrode and the second electrode, the capacitance C _B of FIG. 3, the second electrode and the reference potential point GND It corresponds to the capacitance between. Hereinafter, synthesis capacity of the capacitance C _A and the capacitance C _B "synthetic capacitance Cs'".

  Therefore, when the second control is performed, the capacitance Ct between the operating body and the first electrode becomes a capacitance related to the reference potential point. Impact is eliminated.

  Here, when the first control is performed, that is, when the cancel control is performed, the capacitance of the first electrode functioning as the sensor electrode is, as described above, “first electrode (sensor electrode)”. Capacitance Cp1 between the second electrode (cancellation electrode) and the capacitance Cp2 between the second electrode (cancellation electrode) and the reference potential point GND.

  In addition, when cancel control is performed, if the capacitance Cs of the first electrode (sensor electrode) varies, the first electrode (sensor electrode) and the second electrode (cancel electrode) may vary depending on the variation of the capacitance Cs. The fluctuation of the capacitance Cp1 between and becomes dominant.

  When the second control is performed, as described above, the influence of the capacitance caused by the operating body is eliminated. Therefore, if the fluctuation of the combined capacitance Cs ′ when the second control is performed is approximated with the fluctuation of the capacitance Cs of the first electrode when the cancel control is performed, the fluctuation of the combined capacitance Cs ′ is This can be regarded as a change in the capacitance Cs of the first electrode due to a change in the external environment.

Therefore, the input device according to the embodiment of the present invention has a configuration in which the following condition is satisfied when the second control is performed.
-The electrostatic capacitance between the second electrode and the reference potential point is sufficiently smaller than the electrostatic capacitance between the first electrode and the second electrode.

  Here, as an example of the configuration of the input device that satisfies the condition according to the embodiment of the present invention, “the capacitance between the second electrode and the reference potential point is the static between the first electrode and the second electrode. “It must be at least four times the electric capacity”. For example, one or more of a material such as a substrate existing between the second electrode and the reference potential point, a distance between the second electrode and the reference potential point, and an area of the second electrode are set. Thus, the configuration of the input device that satisfies the conditions according to the embodiment of the present invention is obtained.

  Needless to say, the configuration example of the input device that satisfies the conditions according to the embodiment of the present invention is not limited to the example shown above.

By conditions according to an embodiment of the present invention are satisfied, the combined capacitance Cs' is the capacitance C _A between the first electrode and the second electrode is dominant synthesis capacity. At this time, the fluctuation of the combined capacitance Cs ′ in a certain period approximates the fluctuation of the capacitance Cs of the first electrode in the period.

  Therefore, the input device according to the embodiment of the present invention performs the second control, thereby “capacitance of the first electrode (sensor electrode) due to a change in the external environment that may occur when the first control is performed. Cs fluctuation amount "can be acquired. An example of a method for acquiring the amount of change in the capacitance of the first electrode due to a change in the external environment, that is, an example of a method for acquiring the amount of change in the capacitance of the first electrode due to other than the operating body will be described later.

  In addition, by acquiring the variation in the capacitance Cs of the first electrode due to the change in the external environment, the input device according to the embodiment of the present invention corrects the variation in the capacitance Cs. Thus, the operation can be detected. An example of a correction method for the variation in the capacitance Cs of the first electrode caused by the change in the external environment will be described later.

  Therefore, by performing the second control in addition to the first control corresponding to the cancel control, the input device according to the embodiment of the present invention can perform the operation by the operating body more than the case where only the cancel control is performed. The detection accuracy can be improved.

[2-3] Switching between first control and second control Next, switching between the first control and the second control in the input apparatus according to the embodiment of the present invention will be described.

  The input device according to the embodiment of the present invention performs the first control when an operation on the switch unit is not detected. That is, the input device according to the embodiment of the present invention performs cancel control and detects an operation on the switch unit.

  Further, the input device according to the embodiment of the present invention performs the first control and the second control by alternately performing the first control and the second control after the operation on the switch unit is detected. Switch.

  The input device according to the embodiment of the present invention performs the second control every time a predetermined time elapses.

  Here, examples of the predetermined time according to the embodiment of the present invention include a set fixed period. The certain period may be a fixed period set in advance, or may be a variable period that can be changed based on an operation of the user of the input device according to the embodiment of the present invention. When the predetermined time is a fixed period, the second control is repeatedly performed at a fixed timing.

  Note that the predetermined time according to the embodiment of the present invention is not limited to a certain period. For example, the predetermined time may be a period in which the time interval varies randomly or according to a predetermined rule.

  Further, in the input device according to the embodiment of the present invention, the amount of change in the capacitance of the first electrode is acquired by, for example, a method for acquiring the amount of change in the capacitance of the first electrode by means other than the operating body described later. In this case, switching between the first control and the second control is stopped, and the first control is performed. The input device according to the embodiment of the present invention corrects the change in the capacitance of the first electrode by a correction method for the change in the capacitance Cs of the first electrode caused by a change in the external environment described later. Then, an operation on the switch unit is detected.

[3] Configuration Example of Input Device According to Embodiment of the Present Invention Hereinafter, an example of the configuration of the input device according to the embodiment of the present invention will be described, and processing in the input device according to the embodiment of the present invention will be described more specifically. I will explain it.

  FIG. 4 is a block diagram showing an example of the configuration of the input device 100 according to the embodiment of the present invention. The input device 100 includes, for example, a switch unit 102, a detection unit 104, and a control unit 106.

  The input device 100 may include, for example, a ROM (Read Only Memory) (not shown), a RAM (Random Access Memory) (not shown), a storage unit (not shown), and the like. For example, the input device 100 connects the above-described components by a bus as a data transmission path. The input device 100 is driven by, for example, power supplied from an internal power source such as a battery provided in the input device 100 or power supplied from a connected external power source.

  A ROM (not shown) stores data such as programs and calculation parameters used by the control unit 106 and a processing circuit 114 described later, for example. A RAM (not shown) temporarily stores programs executed by the control unit 106, the processing circuit 114, processing data, and the like.

  The storage unit (not shown) is a storage unit included in the input device 100. The storage unit (not shown) stores various data such as application software.

  Here, examples of the storage unit (not shown) include a magnetic recording medium such as a hard disk, and a nonvolatile memory such as a flash memory. The storage unit (not shown) may be detachable from the input device 100.

[3-1] Switch unit 102
The switch unit 102 includes a first electrode E1 and a second electrode E2. Between the 1st electrode E1 and the 2nd electrode E2, the board | substrate with which an insulator base material is used is provided, for example. Although not shown in FIG. 4, a substrate using an insulating base material is provided between the second electrode E2 and the reference potential point, for example.

  When the first control is performed, the first electrode E1 functions as a sensor electrode, and the second electrode E2 functions as a cancel electrode.

  When the second control is performed, the first electrode E1 has the same potential as the reference potential point, and the second electrode E2 functions as a sensor electrode.

  In addition, the switch unit 102 has, for example, “the electrostatic capacitance between the second electrode E2 and the reference potential point is sufficiently smaller than the electrostatic capacitance between the first electrode E1 and the second electrode E2.” It is configured to satisfy the condition.

As described above, by the above condition is satisfied, the combined capacitance when the second control is performed Cs' is the dominant capacitance C _A between the first electrode E1 and second electrode E2 Combined capacity. In addition, when the above condition is satisfied, the change in the composite capacitance Cs ′ in a certain period approximates the change in the capacitance Cs of the first electrode E1 in the period.

[3-2] Detection unit 104
[3-2-1] Processing in Detection Unit 104 The detection unit 104 detects an operation on the switch unit 102 based on a change in the capacitance of the first electrode E1. The detection unit 104 detects an operation on the switch unit 102 when the first control is performed, that is, when a drive signal is applied to the first electrode E1.

  The detection unit 104 detects the capacitance values of the first electrode E1 and the second electrode E2 by a self-capacitance method. For example, the detection unit 104 sets the first electrode E1 to which the drive signal is applied or the second electrode E2 to which the drive signal is applied as the detection target of the capacitance value. The detection unit 104 sets the first electrode E1 as a capacitance value detection target when the first control is performed or when the second control is performed. The detection unit 104 sets the second electrode E2 as a capacitance value detection target when the second control is performed.

  When detecting an operation on the switch unit 102, the detection unit 104 compares the detected capacitance value of the first electrode E1 with a predetermined threshold value, thereby performing an operation on the switch unit 102. Detect what happened.

  Here, the predetermined threshold value according to the embodiment of the present invention may be a fixed threshold value that is set in advance, or may be a variable threshold value that changes based on an operation detection result in the detection unit 104. Good. As an example of the variable threshold value based on the operation detection result, for example, “when an operation is detected by the detection unit 104, the threshold value is set to be higher than the threshold value set before the operation is detected by the detection unit 104. “A smaller value is set”.

  When the first control is performed, the capacitance of the first electrode E1 changes, for example, when an operating body such as a finger approaches the first electrode E1. The detection unit 104 detects a change in the capacitance of the first electrode E1 by threshold processing using a predetermined threshold as described above, and detects an operation on the switch unit 102.

  Specifically, the detection unit 104, for example, when the detected capacitance value of the first electrode E1 is greater than or equal to a predetermined threshold (or when the capacitance value is greater than the predetermined threshold). , It detects that the switch unit 102 has been operated.

  For example, when an operation on the switch unit 102 is detected, the detection unit 104 determines that an operation has been performed on the switch unit 102.

  In addition, the detection method of the operation with respect to the switch part 102 in the detection part 104 is not restricted above. For example, the detection unit 104 can determine that an operation on the switch unit 102 has been performed when an operation is detected a predetermined number of times. The predetermined number of times according to the embodiment of the present invention may be a fixed number set in advance, or a variable number that can be changed based on a command from the control unit 106 or an external controller. .

  As described above, when the detection unit 104 determines that an operation has been performed on the switch unit 102 when an operation is detected a predetermined number of times, the possibility of erroneous detection of the operation on the switch unit 102 is further reduced. can do.

  More specifically, the detection unit 104 performs, for example, the process shown in (I) below and the process (II) below, and selectively changes the capacitance of the first electrode E1 other than the operating body. And the operation on the switch unit 102 is detected. Hereinafter, the change in capacitance of the first electrode E1 due to other than the operating body may be referred to as “change in capacitance of the first electrode E1”.

(I) Calculation process of capacitance change amount of first electrode E1 other than the operating body The detection unit 104 calculates the capacitance change amount of the first electrode E1 other than the operation body. Hereinafter, the amount of change in the capacitance of the first electrode E1 due to other than the operating body may be referred to as “the amount of change in the capacitance of the first electrode E1” or simply “the amount of change”.

  As described above, by performing the second control, the influence of the electrostatic capacitance caused by the operating body is eliminated. Further, when the switch unit 102 satisfies the condition according to the embodiment of the present invention, the change in the combined capacitance Cs ′ in a certain period approximates the change in the capacitance Cs of the first electrode E1 in the period.

  Therefore, the detection unit 104, for example, the capacitance Cs of the first electrode E1 when the operation is not detected and the capacitance Cs of the first electrode E1 at the plurality of times when the second control is performed. Based on ', the amount of change in the capacitance of the first electrode E1 other than the operating body is calculated.

  More specifically, the detection unit 104 calculates the amount of change in the capacitance of the first electrode E1 due to other than the operating body, for example, by performing the calculation shown in the following Equation 2.

  Here, “ΔCs” shown in Equation 2 below is the amount of change in the capacitance of the first electrode E1. Further, “Cs” shown in Equation 2 below is the capacitance of the first electrode E1 detected when the operation is not detected, and is detected when the first control is performed. This corresponds to the capacitance of one electrode E1. Further, “Cs′1” shown in Equation 2 below is the capacitance of the first electrode E1 detected at the first time point when the second control is performed. In addition, “Cs′2” shown in the following formula 2 is the second time point detected at the second time point when the second control is performed (the second time point is a time point after the first time point). This is the capacitance of one electrode E1.

  For example, by performing the calculation shown in Equation 2, the rate of change of the combined capacitance Cs ′ after the elapse of ΔT (ΔT is the period between the first time point and the second time point) is used. Thus, the amount of change in the capacitance of the first electrode E1 after ΔT has elapsed is estimated. Further, the change in the composite capacitance Cs ′ is obtained by eliminating the influence of the electrostatic capacitance caused by the operating body.

  Therefore, for example, the amount of change in the capacitance of the first electrode E1 calculated by the calculation shown in Equation 2 can be said to be the amount of change in the capacitance Cs of the first electrode E1 due to a change in the external environment.

  In addition, the calculation method of the amount of change in the capacitance of the first electrode E1 is not limited to the method using the calculation shown in Equation 2 above. For example, the detection unit 104 calculates the amount of change in the capacitance of the first electrode E1 using the capacitance Cs ′ of the first electrode E1 at three or more time points when the second control is performed. It is also possible to do.

  For example, the detection unit 104 repeatedly calculates the amount of change in the capacitance of the first electrode E1 periodically or irregularly. When the amount of change is calculated repeatedly, the detection unit 104 corrects the amount of change in the capacitance of the first electrode E1 using the newly calculated amount of change in the following process (II).

  Note that the detection unit 104 may calculate the amount of change in the capacitance of the first electrode E1 only once. Further, the detection unit 104 does not have to calculate a new change amount until a command for calculating the change amount of the capacitance of the first electrode E1 is acquired. The calculation command is acquired, for example, when a predetermined operation of the user of the input device according to the embodiment of the present invention is performed.

(II) Operation detection processing for the switch unit 102 When the amount of change in the capacitance of the first electrode E1 is calculated, the detection unit 104 determines the capacitance of the first electrode E1 based on the calculated amount of change. The change is corrected and an operation on the switch unit 102 is detected.

  The detection unit 104, for example, “adds a correction value corresponding to the calculated change amount to a predetermined threshold value related to the detection of the operation” or “adds the detected capacitance value of the first electrode E1 to the detected capacitance value. By adding a correction value corresponding to the calculated change amount, ”the change in capacitance of the first electrode E1 is corrected. Here, the detection unit 104 refers to, for example, a “table (or database) in which the change amount and the correction value are associated” stored in a recording medium such as a storage unit (not shown). Thus, a correction value corresponding to the calculated change amount is specified.

  Note that the method for correcting the change in the capacitance of the first electrode E1 (the correction method for the change in the capacitance Cs of the first electrode due to the change in the external environment) is not limited to the above example. Needless to say.

  In addition, when the amount of change in the capacitance of the first electrode E1 is not calculated, the detection unit 104 operates the switch unit 102 without correcting the amount of change in the capacitance of the first electrode E1. To detect.

[3-2-2] Configuration Example of Detection Unit 104 Next, an example of the configuration of the detection unit 104 capable of performing the processing in the detection unit 104 described above will be described.

  The detection unit 104 includes, for example, a voltage source 110, a measurement circuit 112, a processing circuit 114, switching circuits SW1, SW2, SW3, SW4, SW5, and SW6, and ground capacitors C1 and C2.

  The voltage source 110 outputs a drive signal (voltage signal) for driving the first electrode E1 or the second electrode E2. Note that the voltage source 110 may be a voltage source external to the input device 100.

  For example, the measurement circuit 112 detects a capacitance value (self-capacitance value) by measuring a charging time of the capacitor. For example, the measurement circuit 112 measures the charge time of the capacity using one or two or more comparators, and detects the capacitance value by obtaining the capacity value from the measured charge time.

  Note that the measurement circuit 112 is not limited to the example shown above. The measurement circuit 112 can take a configuration corresponding to any method capable of measuring a capacitance value.

  The processing circuit 114 performs the processing in the detection unit 104 described above based on the capacitance value of the first electrode E1 and the capacitance value of the first electrode E2 detected by the measurement circuit 112. For example, the processing circuit 114 recognizes the control performed in the input device 100 based on a control signal indicating the content of the control transmitted from the control unit 106.

  More specifically, the processing circuit 114 detects an operation on the switch unit 102 based on the capacitance value of the first electrode E1 detected by the measurement circuit 112. The processing circuit 114 corrects the change in the capacitance of the first electrode E1 by, for example, performing the processing (I) and the processing (II), and detects an operation on the switch unit 102.

  Here, when the amount of change in the capacitance of the first electrode E1 is calculated, the processing circuit 114 corrects the amount of change in the capacitance of the first electrode E1, and detects an operation on the switch unit 102. To do. Further, when the amount of change in the capacitance of the first electrode E1 is not calculated, the processing circuit 114 performs an operation on the switch unit 102 without correcting the amount of change in the capacitance of the first electrode E1. To detect.

  As the processing circuit 114, for example, one or two or more processors configured by an arithmetic circuit such as a CPU (Central Processing Unit) can be cited.

  The switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 are constituted by, for example, switching transistors, and are turned on (conductive state) or off (non-conductive state) according to the signal level (voltage level) of the applied signal. )

  Examples of the switching transistor include bipolar transistors, and FETs (Field-Effect Transistors) such as TFTs (Thin Film Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors).

  For example, the control unit 106, which will be described later, controls the switching between the ON state and the OFF state of each of the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6.

  Note that the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 are not limited to switching transistors, and may be any elements (or circuits) that can be switched between an on state and an off state.

  In the detection unit 104, for example, as shown in (a) and (b) below, the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 are turned on and off in accordance with the control performed in the input device 100, for example. The state is switched.

(A) When the first control is performed Switching circuits SW1, SW2, SW3: ON state Switching circuits SW4, SW5, SW6: OFF state

(B) When the second control is performed • Switching circuits SW3, SW4, SW5: on state • Switching circuits SW1, SW2, SW6: off state

  For example, by performing on / off control of the switching circuits SW1, SW2, SW3, SW4, SW5, SW6 as shown in (a) above, the first electrode E1 and the second electrode E2 constituting the switch unit 102 are As shown in FIG. Further, for example, the first electrode E1 and the second electrode constituting the switch unit 102 are performed by performing on / off control of the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 as shown in (b) above. E2 is in a state as shown in FIG. In the detection unit 104, the measurement circuit 112 detects the capacitance value (self-capacitance value) of the electrode functioning as the sensor electrode.

  The switching circuit SW6 is a switching circuit for initializing measurement of the capacitance value.

For example, as shown below, the switching of the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 is switched between the on state and the off state, whereby the measurement of the capacitance value is initialized.
Switching circuit SW6: ON state Switching circuit SW1, SW2, SW3, SW4, SW5: OFF state

  The grounding capacitor C1 is connected, for example, between the first electrode E1 and the switching circuit SW2. The grounding capacitor C1 may be a parasitic capacitor or a circuit element such as a capacitor.

  The grounding capacitor C2 is connected between the second electrode E2 and the switching circuit SW3, for example. The ground capacitance C2 may be a parasitic capacitance or a circuit element such as a capacitor.

  The detection unit 104 detects an operation on the switch unit 102 based on a change in the capacitance of the first electrode E1, for example, with the configuration shown in FIG.

  The configuration of the detection unit 104 is not limited to the example illustrated in FIG.

  For example, the detection unit 104 can take an arbitrary configuration capable of measuring the capacitance values (self-capacitance values) of the first electrode E1 and the second electrode E2.

  The detection unit 104 may include a plurality of detection circuits, for example, a detection circuit that measures the capacitance value of the first electrode E1 and a detection circuit that measures the capacitance value of the second electrode E2. .

  For example, when the control unit 106 described later has a function of performing the same processing as the processing circuit 114, the detection unit 104 may not include the processing circuit 114.

[3-3] Control unit 106
The control unit 106 performs first control (control for detecting an operation on the switch unit 102) or second control (for acquiring a change amount of the capacitance of the first electrode E1 other than the operation body). Control).

  The control unit 106 performs first control when no operation is detected by the detection unit 104. The control unit 106 alternately performs the first control and the second control after the operation is detected by the detection unit 104. For example, the control unit 106 performs the second control every time a predetermined time elapses.

  For example, the control unit 106 transmits a signal for switching between the on state and the off state to each of the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 included in the detection unit 104, so that the first Control or second control is performed.

  In addition, the control unit 106 transmits the control signal including a command to switch the on state / off state of each switching circuit to the processing circuit 114 configuring the detection unit 104, for example, thereby performing the first control or The second control may be performed. When the control unit 106 transmits the control signal to the processing circuit 114, in the detection unit 104, the processing circuit 114 applies to each of the switching circuits SW1, SW2, SW3, SW4, SW5, and SW6 based on the transmitted control signal. Thus, a signal for switching between the on state and the off state is transmitted.

  Note that the control in the control unit 106 is not limited to the example shown above. For example, the control unit 106 may serve to control the entire input device 100.

  The control unit 106 includes, for example, one or two or more processors and various processing circuits configured by an arithmetic circuit such as a CPU.

  The input device 100 has a configuration shown in FIG. 4, for example.

  When the first control is performed, the first electrode E1 and the second electrode E2 constituting the switch unit 102 are in a state as shown in FIG. Moreover, when 2nd control is performed, the 1st electrode E1 and 2nd electrode E2 which comprise the switch part 102 will be in a state as shown in FIG.

  Further, the detection unit 104 calculates the amount of change in the capacitance of the first electrode E1, corrects the amount of change in the capacitance of the first electrode E1 due to other than the operating body based on the calculated amount of change, An operation on the switch unit 102 is detected.

  Here, it can be said that the change amount calculated by the detection unit 104 is the change amount of the capacitance Cs of the first electrode E1 due to the change of the external environment, as described above. That is, even when the capacitance Cs of the first electrode E1 varies due to a change in the external environment such as a temperature change or a humidity change after the operation on the switch unit 102 is performed, the detection unit 104 Can detect the operation on the switch unit 102 after correcting the fluctuation of the capacitance Cs.

  Therefore, the input device 100 shown in FIG. 4 can improve the detection accuracy of the operation by the operating tool, compared with the case where only the cancel control is performed.

  In addition, the structure of the input device which concerns on embodiment of this invention is not restricted to the structure shown in FIG.

  For example, FIG. 4 shows an example in which one switch unit 102 is provided, but the input device according to the embodiment of the present invention may be configured to have a plurality of switch units 102. That is, the input device according to the embodiment of the present invention can be configured to include a plurality of self-capacitance type electrostatic switches.

  4 shows an example in which the drive signal output from the voltage source 110 is applied to each of the first electrode E1 and the second electrode E2, the input device according to the embodiment of the present invention When the control 2 is performed, a signal having the same waveform as the drive signal may be applied to the second electrode E2 from a voltage source different from the voltage source 110.

  Further, for example, an input device having functions similar to those of the switch unit 102 and the detection unit 104 illustrated in FIG. 4 and a processing device (for example, a microcomputer outside the input device) having functions similar to the control unit 106. Thus, a system having the same function as the input device 100 shown in FIG. 4 is realized.

[4] Application Example of Input Device According to Embodiment of the Present Invention An input device according to an embodiment of the present invention is, for example, a vehicle such as a vehicle (or a UI (User Interface) part constituting a vehicle system). It can be applied to various systems and devices such as communication devices such as mobile phones and smartphones, tablet devices, television receivers, and computers such as PCs (Personal Computers).

[5] Program according to the embodiment of the present invention A program for causing a computer to function as the input device according to the embodiment of the present invention (for example, a program for causing the computer to function as the processing unit 114 and the control unit 106 illustrated in FIG. 4). However, the detection accuracy of the operation by the operating body can be improved by being executed by the processor or the like in the computer.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above description, it is shown that a program (computer program) for causing a computer to function as an input device according to the embodiment of the present invention is provided. However, the embodiment of the present invention further stores the program. The recorded recording medium can also be provided.

DESCRIPTION OF SYMBOLS 100 Input device 102 Switch part 104 Detection part 106 Control part E1 1st electrode E2 2nd electrode GND Reference potential point

Claims (7)

A switch unit having a first electrode and a second electrode provided between the first electrode and a reference potential point;
A detection unit that detects an operation on the switch unit based on a change in capacitance of the first electrode;
A first control for applying a drive signal to the first electrode and applying a signal having the same waveform as the drive signal to the second electrode based on the detection result of the operation; A controller that performs a second control of connecting an electrode to the reference potential point and applying the drive signal to the second electrode;
An input device comprising: The first control is a control for detecting an operation on the switch unit;
2. The input device according to claim 1, wherein the second control is a control for acquiring a change amount of a capacitance of the first electrode except by an operating body. The controller is
When the operation is not detected, the first control is performed,
The input device according to claim 1, wherein after the operation is detected, the first control and the second control are alternately performed.   The input device according to claim 3, wherein the control unit performs the second control every time a predetermined time elapses. The detector is
Based on the capacitance of the first electrode at a time when the operation is not detected and the capacitance of the first electrode at a plurality of times at which the second control is performed. Calculating the amount of change in capacitance of the first electrode;
When the amount of change is calculated, based on the calculated amount of change, an amount of change in the capacitance of the first electrode other than the operation body is corrected to detect an operation on the switch unit. The input device according to claim 3 or 4, characterized in that:   The input device according to claim 5, wherein when the change amount is not calculated, the detection unit detects an operation on the switch unit without correcting the change. In the case where the second control is performed, the capacitance between the second electrode and the reference potential point is more than the capacitance between the first electrode and the second electrode. The input device according to claim 1, wherein the input device is sufficiently small.

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