Input device and control method for input device

Abstract

To provide an input device capable of executing calibration reliably while suppressing malfunction.SOLUTION: An input device 1 of an electronic device 10 includes: an input unit 2 with a plurality of sensors arranged in a grid; an amount-of-change calculation unit 3 which calculates the amount of change in capacitance detected by each of the sensors with respect to time; a total amount-of-change computation unit 4 which computes the total amount of change in at least a partial region of the input unit from the amount of change of each of the sensors; an operation determination unit 5 which determines that the at least partial region of the input unit is in a non-operation state when the total amount of change is smaller than a predetermined determination value; a calibration determination unit 6 which measures the duration of the determined non-operation state, and determines that calibration is executable when the duration is longer than a predetermined determination time; and a calibration execution unit 7 which executes calibration on the at least partial region of the input unit when a determination is made that calibration is executable.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to an input device and a method for controlling an input device. [Background technology]

[0002] A touch panel equipped with multiple sensors whose capacitance changes when an operator touches it with their finger has been disclosed as an input device for electronic devices. In such a touch panel, the capacitance value when no touch input operation is performed is used as a reference value, and the change in capacitance when the operator touches it with their finger is detected to detect the touch position. However, because the reference value fluctuates due to disturbances such as changes in ambient temperature, it is necessary to periodically perform calibration to reset the reference value.

[0003] In conventional touch panels, the capacitance values ​​of multiple sensors are constantly detected, and when the detected capacitance value does not exceed a threshold, it is determined that no input operation is being performed.A calibration method has been disclosed in which the detected capacitance value is reset as a reference value when it is determined that no input operation is being performed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-97510 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been an increasing demand for touchless panels that do not require direct contact with the touch panel to avoid finger contamination due to contact with the touch panel and the spread of harmful substances through the touch panel. Touchless panels have the same basic configuration as touch panels, and detect the touch position by detecting a change in capacitance when an operator's finger approaches. In such touchless panels, the change in capacitance when an operator's finger approaches is smaller than the change in capacitance when the operator's finger touches the panel. In conventional touch panels, an input operation is determined to have occurred when the detected capacitance value exceeds a threshold. Therefore, when this method is applied to touchless panels, the threshold for the capacitance value must be set low. However, the reference capacitance value may fluctuate due to changes in ambient temperature and humidity, temperature rise due to aging after power-on, and the influence of conductive or magnetic objects around the touchless panel, which can cause the reference capacitance value to exceed the threshold. In conventional touch panels, an input operation is determined to have occurred when the reference capacitance value exceeds the threshold, which can result in calibration not being performed or malfunctioning. In other words, there is a problem in that the conventional method of determining whether or not an input operation has occurred by setting a threshold value for the capacitance value cannot be applied to the calibration of a touchless panel.

[0006] The present application has been made to solve the above-mentioned problems, and has an object to provide an input device that can suppress malfunctions and perform calibration reliably. [Means for solving the problem]

[0007] The input device according to the present application includes an input unit in which a plurality of sensors for detecting capacitance are arranged in a grid pattern, and a capacitance detected by each of the sensors. and a capacitance acquisition unit that acquires the capacitance of each sensor acquired by the capacitance acquisition unit. A change amount calculation unit that calculates a change amount over time of a determination value determination unit that determines a determination value based on the maximum value of the capacitance of each sensor acquired by the capacitance acquisition unit; The change amount calculated by the change amount calculation unit Strange a total change amount calculation unit that calculates a total change amount of at least a part of the region of the input section from the amount of change; and The value determined by the decision value determination unitan operation determination unit that determines that at least a part of the area of ​​the input unit is in a no-operation state when the difference is smaller than a determination value; a calibration feasibility determination unit that measures a duration during which the operation determination unit has determined that at least a part of the area of ​​the input unit is in a no-operation state, and determines that calibration is executable when the duration is longer than a predetermined determination time; and to At least a part of the input area Calibrating the capacitance reference value and a calibration execution unit that executes the calibration. [Effects of the Invention]

[0008] The input device according to the present application is configured to detect capacitances detected by the respective sensors. and a capacitance acquisition unit that acquires the capacitance of each sensor acquired by the capacitance acquisition unit. A change amount calculation unit that calculates a change amount over time of a determination value determination unit that determines a determination value based on the maximum value of the capacitance of each sensor acquired by the capacitance acquisition unit; The change amount calculated by the change amount calculation unit Strange a total change amount calculation unit that calculates a total change amount of at least a part of the region of the input section from the amount of change; and The value determined by the decision value determination unit The device is provided with an operation determination unit that determines that at least a part of the area of ​​the input unit is in a non-operated state when the difference is smaller than a determination value, and a calibration feasibility determination unit that measures the duration during which the operation determination unit has determined that at least a part of the area of ​​the input unit is in a non-operated state and determines that calibration can be performed when the duration is longer than a predetermined determination time, thereby suppressing malfunctions and reliably Calibrating the capacitance reference value Calibration can be performed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of an input device according to a first embodiment. [Figure 2] FIG. 2 is a configuration diagram of an input unit according to the first embodiment. [Figure 3] 4 is a flowchart of calibration according to the first embodiment. [Figure 4] 10 is a flowchart of calibration according to the second embodiment. [Figure 5] FIG. 10 is a configuration diagram of an input device according to a third embodiment. [Figure 6] 11 is a flowchart of calibration according to the third embodiment. [Figure 7] FIG. 1 is a schematic diagram illustrating an example of hardware of a change amount calculation unit, a total change amount calculation unit, an operation determination unit, a calibration feasibility determination unit, a calibration execution unit, a capacitance acquisition unit, and a determination value determination unit of an input device according to first to third embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] An input device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0011] Embodiment 1 1 is a configuration diagram of an input device according to embodiment 1. The input device 1 of this embodiment is an input device for operating an electronic device 10. The electronic device 10 is, for example, a ticket machine at a station, an ATM (Automatic Teller Machine) at a bank, a medical device, an in-vehicle device, or the like. The input device 1 includes an input unit 2 in which a plurality of sensors for detecting capacitance are arranged in a grid pattern; a change amount calculation unit 3 that calculates the amount of change over time in capacitance detected by each sensor; a total change amount calculation unit 4 that calculates a total amount of change in the input unit 2 from the amount of change in each sensor calculated by the change amount calculation unit 3; an operation determination unit 5 that determines that the input unit 2 is in an unoperated state when the total amount of change in the input unit 2 calculated by the total change amount calculation unit 4 is smaller than a predetermined determination value; a calibration feasibility determination unit 6 that measures the duration during which the operation determination unit 5 has determined that the input unit 2 is in an unoperated state and determines that calibration is possible when the duration is longer than the predetermined determination time; and a calibration execution unit 7 that calibrates the reference values ​​of capacitance for the plurality of sensors when the calibration feasibility determination unit 6 determines that calibration is possible.

[0012] FIG. 2 is a configuration diagram of the input unit 2. The input unit 2 has first electrode lines x1, x2, x3, . . . x19 and second electrode lines y1, y2, y3, . . . y11 arranged in a grid pattern. When an operator's finger approaches an electrode, capacitive coupling occurs between the finger and the electrode, causing a change in the capacitance of the capacitor of that electrode. The touch position of the operator's finger can be detected by detecting this change in capacitance on both electrode lines. In other words, the input unit 2 is a touchless panel in which multiple sensors are arranged in a grid pattern. Note that the structure of the input unit 2, which detects the touch position of the operator's finger based on changes in capacitance, is not limited to the structure shown in FIG. 2.

[0013] Next, a description will be given of a calibration method for the input device 1 of this embodiment. Here, calibration in this embodiment means calibrating the zero point that serves as a reference for the change in capacitance in a sensor that detects an object based on the change in capacitance, that is, the reference value of the capacitance value.

[0014] FIG. 3 is a flowchart of the calibration in this embodiment. In step S1, the change amount calculation unit 3 acquires the capacitance value of each sensor from each electrode line (x1, x2, x3, . . . x19, y1, y2, y3, . . . y11) of the input unit 2 at intervals of several tens of milliseconds. Next, in step S2, the change amount calculation unit 3 calculates the difference between the current capacitance value of each xn (n = 1, 2, . . . 19) and the capacitance value from a certain time ago to calculate the change in the capacitance value of xn over time. Note that the change in the capacitance value over time can also be rephrased as the change in the capacitance value over time. The capacitance value from a certain time ago in step S2 can be obtained, for example, by repeatedly acquiring the capacitance value of each sensor at intervals of several tens of milliseconds in step S1. In step S3, the total change amount calculation unit 4 calculates the sum of the changes in the capacitance value of xn over time as the total change in the input unit 2. In step S4, the operation determination unit 5 determines whether the total amount of change in the input unit 2 calculated by the total change amount calculation unit 4 is smaller than a predetermined determination value. Here, a state in which the total amount of change in the input unit 2 is smaller than the predetermined determination value is referred to as a no-operation state. If the total amount of change in the input unit 2 is smaller than the predetermined determination value in step S4, i.e., if the no-operation state is determined (YES), the calibration feasibility determination unit 6 measures the duration of the no-operation state in step S5 and determines whether this duration is longer than the predetermined determination time. If the duration of the no-operation state is equal to or shorter than the predetermined determination time in step S5 (NO), the calibration feasibility determination unit 6 determines that calibration cannot be performed and returns the input device 1 to step S1. If the duration of the no-operation state is longer than the predetermined determination time in step S5 (YES), the calibration feasibility determination unit 6 determines that no input operation has been performed on the input unit 2 and that the surrounding environment is stable. Then, the calibration feasibility determination unit 6 determines that calibration is executable and instructs the calibration execution unit 7 to perform calibration. In step S6, the calibration execution unit 7 executes calibration for the plurality of sensors of the input unit 2. The calibration execution unit 7 sets the average value of the capacitance values ​​of the sensors repeatedly acquired in step S1, for example, as a reference value.The calibration performed by the calibration execution unit 7 is not limited to this.

[0015] The determination time in step S5 is, for example, 4 seconds. If the no-operation state continues for a time longer than 4 seconds, the calibration feasibility determination unit 6 can determine that no input operation is being performed on the input unit 2 and that the surrounding environment is stable. In order for the calibration feasibility determination unit 6 to determine that no input operation is being performed on the input unit 2 and that the surrounding environment is stable, the determination time in step S5 is preferably set to a value between 3 seconds and 5 seconds. Note that in step S4, if the total amount of change in the input unit 2 is equal to or greater than a predetermined determination value (NO), the operation determination unit 5 determines that an input operation is being performed on the input unit 2. Then, the operation determination unit 5 returns the input device 1 to step S11. Note that the calibration operation shown in FIG. 3 is always performed repeatedly.

[0016] In conventional touch panels, an input operation is determined to have occurred when the capacitance value detected by each sensor exceeds a threshold value. When this touch panel is used as a touchless panel, the threshold value is set small. Therefore, if the reference value of the capacitance value fluctuates beyond the threshold value due to changes in ambient temperature or the like, the fluctuation is determined to be an input operation, and calibration is not performed. In contrast, in the input device of this embodiment, whether or not an input operation has occurred on the input unit is determined based on the amount of change in the capacitance value of the electrode line over time. Therefore, even if the reference value of the capacitance value fluctuates beyond the threshold value, the amount of change over time is small, so it can be determined that no input operation has occurred. As a result, the input device of this embodiment can suppress malfunctions and reliably perform calibration even if the reference value of the capacitance value fluctuates beyond the threshold value.

[0017] In this embodiment, the change amount calculation unit 3 calculates the change over time in the capacitance value of xn, but it may also calculate the change over time in the capacitance value of yn. It may also calculate the change over time in the capacitance value of each sensor. Regardless of the method, the change amount calculation unit 3 calculates the change over time in the capacitance detected by each sensor. While the total change amount calculation unit 4 calculates the simple sum of the changes in xn as the total change in the input unit, other calculation methods may be used. For example, the change in the electrode lines at the outer edge, which are susceptible to the influence of external temperature, or in the vicinity of other heat-generating components, may be weighted by a weight of 1 or less to obtain the sum. By performing a weighted calculation by the total change amount calculation unit 4, the influence of fluctuations in sensors, which are susceptible to environmental changes, can be suppressed.

[0018] Embodiment 2 In the input device of embodiment 1, the total change amount calculation unit calculates the total change amount of the entire input unit. In the input device of embodiment 2, the total change amount calculation unit calculates the total change amount of a partial region of the input unit. The configuration of the input device of embodiment 2 is similar to the configuration of the input device of embodiment 1, but differs in the following respects: the total change amount calculation unit calculates the sum of the change amounts of the partial region of the input unit from the change amounts of the capacitance of the input unit over time calculated by the change amount calculation unit.

[0019] FIG. 4 is a flowchart of the calibration in this embodiment. In step S1, the change amount calculation unit 3 acquires the capacitance value of each sensor from each electrode line (x1, x2, x3, . . . x19, y1, y2, y3, . . . y11) of the input unit 2 at intervals of several tens of milliseconds. Next, in step S2, the change amount calculation unit 3 calculates the difference between the current capacitance value of each xn (n = 1, 2, . . . 19) and the capacitance value from a certain time ago to calculate the change in the capacitance value of xn over time. The capacitance value from a certain time ago in step S2 can be obtained, for example, by repeatedly acquiring the capacitance value of each sensor at intervals of several tens of milliseconds in step S1. In step S3, the total change amount calculation unit 4 calculates the sum of the changes in the capacitance values ​​of xn included in the partial area of ​​the input unit 2 over time as the total change in the partial area. In step S4, the operation determination unit 5 determines whether the total change in the partial area of ​​the input unit 2 calculated by the total change amount calculation unit 4 is smaller than a predetermined determination value. If the total amount of change in the partial area of ​​the input unit 2 is smaller than a predetermined judgment value in step S4, that is, if the input unit 2 is in a no-operation state (YES), the calibration feasibility determination unit 6 measures the duration of the no-operation state in step S5 and determines whether this duration is longer than the predetermined judgment time. If the duration of the no-operation state is equal to or shorter than the predetermined judgment time in step S5 (NO), the calibration feasibility determination unit 6 determines that calibration cannot be performed and returns the input device 1 to step S1. If the duration of the no-operation state is longer than the predetermined judgment time in step S5 (YES), the calibration feasibility determination unit 6 determines that no input operation has been performed on the partial area of ​​the input unit 2 and that the surrounding environment is stable. Then, the calibration feasibility determination unit 6 determines that calibration is executable and instructs the calibration execution unit 7 to execute calibration. In step S6, the calibration execution unit 7 calibrates the reference values ​​of the capacitances of the multiple sensors in the partial area of ​​the input unit 2.

[0020] The input device configured in this manner can suppress malfunction and reliably perform calibration even when the reference value of the capacitance value fluctuates beyond a threshold value, similar to the input device of embodiment 1. Furthermore, the input device of this embodiment can individually perform calibration on some areas that are determined to be in a no-operation state even when an input operation is being performed, thereby increasing the frequency of calibration and allowing it to be performed on a per-area basis.

[0021] In this embodiment, the change amount calculation unit 3 calculates the amount of change over time in the capacitance value of xn, but it may also calculate the amount of change over time in the capacitance value of yn. Also, the amount of change over time in the capacitance value of each sensor may be calculated directly. In either method, the change amount calculation unit 3 calculates the amount of change over time in the capacitance detected by each sensor. Furthermore, the total change amount calculation unit 4 calculates the total amount of change by simply summing up the amount of change in xn in a partial area of ​​the input unit, but other calculation methods may also be used.

[0022] Embodiment 3 When a large conductor is placed near the input device, the capacitance value of the sensor in the input section increases even when no input operation is being performed. As the capacitance value increases, the amount of change in the capacitance value over time due to changes in the ambient temperature and humidity, temperature rise due to aging after power-on, and other factors also increases. In the input devices of the first and second embodiments, the operation determination unit determines whether or not an operation is being performed using a predetermined determination value. However, if the capacitance value of the sensor is large, the total amount of change over time may exceed the predetermined determination value. In this case, if the capacitance value of the sensor in the input section is large, the operation determination unit will determine that an input operation is being performed even when no operation is being performed. The input device of the third embodiment does not use a fixed determination value, but sets the determination value according to the capacitance value of the sensor in the input section, thereby accurately determining a no-operation state even when the capacitance value of the sensor in the input section is large.

[0023] 5 is a configuration diagram of an input device according to this embodiment. An input device 1 according to this embodiment is obtained by adding a capacitance acquisition unit 8 and a judgment value determination unit 9 to the input device according to the first embodiment. The operations of a change amount calculation unit 3, a total change amount calculation unit 4, an operation determination unit 5, a calibration feasibility determination unit 6, and a calibration execution unit 7 are the same as those of the input device according to the first embodiment.

[0024] The capacitance acquisition unit 8 acquires capacitances detected by the multiple sensors of the input unit 2. The capacitance acquisition unit 8 outputs the acquired capacitance values ​​to the change amount calculation unit 3. The capacitance acquisition unit 8 also converts the capacitance values ​​of the multiple sensors into voltages, and then converts them into digital values ​​with a full range of, for example, 500. The capacitance acquisition unit 8 outputs the digital values ​​into which the capacitance values ​​are converted to the judgment value determination unit 9.

[0025] The judgment value determination unit 9 detects the maximum value of the input digital value and determines a judgment value based on that maximum value. For example, the full range is divided into multiple parts, and the judgment value is changed in steps starting from a certain value. Specifically, the judgment value determination unit 9 sets the judgment value to 40 when the maximum digital value is between 1 and 100, 80 when the maximum digital value is between 101 and 200, 120 when the maximum digital value is between 201 and 300, and 160 when the maximum digital value is between 301 and 400. Note that a digital value exceeding 400 is considered to be a level at which an input operation is being performed. The above numerical values ​​are merely an example of increasing the judgment value by 40, and may be adjusted depending on the actual sensor characteristics, device characteristics, etc. The judgment value determination unit 9 outputs a judgment value determined based on the maximum input digital value to the operation determination unit 5. Note that the amount of change in capacitance value over time varies depending on the sensitivity setting of each sensor, so the judgment value determined by the judgment value determination unit 9 is appropriately set depending on the specifications of the input device, etc.

[0026] The operation determination unit 5 uses the input determination value to determine whether the total amount of change in the input unit 2 calculated by the total change amount calculation unit 4 is smaller than the determination value. In the input device 1 of this embodiment, the amount of change in the capacitance value over time calculated by the change amount calculation unit 3 and the total change amount calculation unit 4 is converted into a digital value, similar to the capacitance acquisition unit 8.

[0027] FIG. 6 is a flowchart of the calibration in this embodiment. In step S11, the capacitance acquisition unit 8 acquires the capacitance value of each sensor from each electrode line (x1, x2, x3, . . . x19, y1, y2, y3, . . . y11) of the input unit 2 at intervals of several tens of milliseconds. Next, in step S12, the change amount calculation unit 3 calculates the difference between the current capacitance value of each xn (n = 1, 2, . . . 19) and the capacitance value from a certain time ago to calculate the change amount of the capacitance value of xn over time. The capacitance value from a certain time ago in step S12 can be obtained, for example, by repeatedly acquiring the capacitance value of each sensor at intervals of several tens of milliseconds in step S11. In step S13, the judgment value determination unit 9 determines the judgment value based on the maximum capacitance value. In step S14, the total change amount calculation unit 4 calculates the sum of the changes in the capacitance value of xn over time as the total change amount of the input unit 2. In step S15, the operation determination unit 5 determines whether the total amount of change in the input unit 2 calculated by the total change amount calculation unit 4 is smaller than the determination value determined by the determination value determination unit 9. If the total amount of change in the input unit 2 is smaller than the determination value determined by the determination value determination unit 9 in step S15, that is, if the input unit 2 is in a no-operation state (YES), the calibration feasibility determination unit 6 measures the duration of the no-operation state in step S16 and determines whether this duration is longer than a predetermined determination time. If the duration of the no-operation state is equal to or shorter than the predetermined determination time (NO) in step S16, the calibration feasibility determination unit 6 determines that calibration cannot be performed and returns the input device 1 to step S11. If the duration of the no-operation state is longer than the predetermined determination time (YES) in step S16, the calibration feasibility determination unit 6 determines that no input operation has been performed on the input unit 2 and that the surrounding environment is stable. Then, the calibration feasibility determination unit 6 determines that calibration is executable and instructs the calibration execution unit 7 to perform calibration. The calibration execution unit 7 executes calibration for the plurality of sensors of the input unit 2 in step S17.

[0028] The determination time in step S16 is, for example, 4 seconds. If the no-operation state continues for a time longer than 4 seconds, the calibration feasibility determination unit 6 can determine that no input operation is being performed on the input unit 2 and that the surrounding environment is stable. In order for the calibration feasibility determination unit 6 to determine that no input operation is being performed on the input unit 2 and that the surrounding environment is stable, the determination time in step S16 is preferably set to a value between 3 seconds and 5 seconds. Note that in step S15, if the total amount of change in the input unit 2 is equal to or greater than the determination value determined by the determination value determination unit 9 (NO), the operation determination unit 5 determines that an input operation is being performed on the input unit 2. Then, the operation determination unit 5 returns the input device 1 to step S11. Note that the calibration operation shown in FIG. 6 is always performed repeatedly.

[0029] The input device configured in this manner can suppress malfunction and reliably perform calibration even when the reference value of the capacitance value fluctuates beyond a threshold value, similar to the input device of embodiment 1. Furthermore, the input device of this embodiment sets the determination value to a large value when the capacitance value of the sensor of the input unit is large, so that it can accurately determine the no-operation state even when the capacitance value of the sensor of the input unit is large.

[0030] In the input device of this embodiment, the judgment value determination unit 9 classifies the maximum value of the input digital value into four ranges and sets a fixed judgment value for each range. As an alternative method, the judgment value may be set according to the maximum value of the input digital value. For example, the judgment value may be a value obtained by multiplying the maximum value of the input digital value by a fixed ratio.

[0031] In the input device of this embodiment, the total change amount calculation unit calculates the total change amount of the entire input unit. As in the input device of embodiment 2, the total change amount calculation unit may calculate the total change amount of a partial region of the input unit.

[0032] The change amount calculation unit 3, total change amount calculation unit 4, operation determination unit 5, calibration feasibility determination unit 6, calibration execution unit 7, capacitance acquisition unit 8, and determination value determination unit 9 of the input device 1 described in the first to third embodiments are configured with a processor 100 and a storage device 101, as shown in FIG. 7 , which is an example of hardware. The storage device 101 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory, although these are not shown. Alternatively, an auxiliary storage device such as a hard disk may be included instead of the flash memory. The processor 100 executes a program input from the storage device 101. In this case, the program is input to the processor 100 from the auxiliary storage device via the volatile storage device. The processor 100 may output data such as calculation results to the volatile storage device of the storage device 101, or may store the data in the auxiliary storage device via the volatile storage device.

[0033] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in the present specification, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0034] 1 input device, 2 input section, 3 change amount calculation section, 4 total change amount calculation section, 5 operation determination section, 6 calibration feasibility determination section, 7 calibration execution section, 8 capacitance acquisition section, 9 judgment value determination section, 10 electronic device, 100 processor, 101 storage device.

Claims

1. An input device for an electronic device, an input unit in which a plurality of sensors for detecting capacitance are arranged in a grid pattern; a capacitance acquisition unit that acquires the capacitance detected by each of the sensors; a change amount calculation unit that calculates a change amount over time in the capacitance of each of the sensors acquired by the capacitance acquisition unit; a determination value determination unit that determines a determination value based on the maximum value of the capacitance of each of the sensors acquired by the capacitance acquisition unit; a total change amount calculation unit that calculates a total change amount in at least a partial area of ​​the input unit from the change amount calculated by the change amount calculation unit; an operation determination unit that determines that at least a portion of the area of ​​the input unit is in a no-operation state when the total amount of change in at least a portion of the area of ​​the input unit calculated by the total change amount calculation unit is smaller than the determination value determined by the determination value determination unit; a calibration feasibility determination unit that measures a duration during which the operation determination unit determines that at least a part of the area of ​​the input unit is in a no-operation state, and determines that calibration is executable when the duration is longer than a predetermined determination time; and a calibration execution unit that executes calibration to calibrate the reference value of the capacitance in at least a portion of the area of ​​the input unit when the calibration feasibility determination unit determines that calibration is possible.

2. 2. The input device according to claim 1, wherein the total change amount of at least a portion of the area of ​​the input section calculated by the total change amount calculation unit is a sum of the change amounts of at least a portion of the area of ​​the input section calculated by the change amount calculation unit.

3. 3. The input device according to claim 1, wherein the determination time is set to a value of 3 seconds or more and 5 seconds or less.

4. A control method for an input device having an input unit in which a plurality of sensors that detect capacitance are arranged in a grid, comprising: a capacitance acquisition step of acquiring the capacitance detected by each of the sensors; a change amount calculation step of calculating an amount of change over time in the capacitance of each of the sensors acquired in the capacitance acquisition step; a determination value determination step of determining a determination value based on the maximum value of the capacitance of each of the sensors acquired in the capacitance acquisition step; a total change amount calculation step of calculating a total change amount of at least a partial area of ​​the input section from the change amount calculated in the change amount calculation step; an operation determination step of determining that at least a portion of the area of ​​the input unit is in a no-operation state when the total amount of change in at least a portion of the area of ​​the input unit calculated in the total amount of change calculation step is smaller than the determination value determined in the determination value determination step; a calibration feasibility determination step of measuring a duration during which it is determined in the operation determination step that at least a part of the area of ​​the input unit is in a non-operated state, and determining that calibration is executable when the duration is longer than a predetermined determination time; a calibration execution step of executing calibration to calibrate the reference value of the capacitance in at least a part of the area of ​​the input section when it is determined in the calibration feasibility determination step that calibration is possible.

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