JP2015064859A - Input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitive input device configured to prevent false detection even if noise is generated.SOLUTION: An input device includes: an input section 1 having a plurality of capacitance detection sections 1a and used by an operation body for proximity operation; a capacitance measurement section 2 which measures capacitance for each capacitance detection section 1a and outputs measured capacitance values as data; and a control section 3 which acquires the capacitance value in association with the capacitance detection section 1a, updates a base value by use of the capacitance value, and determines whether a difference between the capacitance value and the base value has exceeded a predetermined threshold, to detect an operation. The control section 3 determines whether there is noise, on the basis of the difference between the capacitance value and the base value, sets a first weight as a weight for weight averaging which updates the base value when absence of noise is determined, and sets a second weight larger than the first weight, as a weight for weighted averaging which updates the base value, or suspends updating when presence of noise is determined.

Description

  The present invention relates to a capacitance-type input device, and more particularly to an input device that can reduce false detection due to noise.

  Conventionally, a capacitance-type input device performs an input operation by detecting a change in capacitance due to a proximity operation by an operation body such as an operator's finger or a touch pen. It is widely used in portable devices such as navigation devices and in-vehicle devices such as navigation devices.

  In a capacitive touch sensor (input device) 800 described in Patent Document 1 (conventional example 1), as shown in FIG. 7, a sensor controller 802, a current source 804, a clock / timer 806, an analog-digital converter (ADC) 808, multiplexer input / output (I / O) 810, and data storage 812.

  In the capacitive touch sensor 800, as shown in FIG. 8, when the voltage measurement signal 904 becomes lower than the touch detection threshold 906, the electrode is determined to be in the touch (operation) state, and the touch release threshold 912. If it is higher than that, it is determined to be in a no-touch (non-operation) state.

  While the electrode is in a no-touch state, the baseline (base value) 902 is dynamically adjusted, and the touch detection threshold 906 and the touch release threshold 912 are also dynamically adjusted as the baseline 902 is dynamically adjusted.

Special table 2013-506905 gazette

  However, in the above-described conventional example, the baseline value is constantly updated during non-operation (no-touch state). Therefore, when noise is added to the capacitive input device (touch sensor), the capacitance due to noise The detected value fluctuations are added to the base value (baseline).

  When the capacitance detection value increases due to noise, the base value increases according to the influence of noise, and the touch detection threshold value and touch release threshold value also increase.

  After the touch detection threshold is increased due to the influence of noise in this way, if noise is removed and the detection value of the capacitance decreases, the detection value may fall as an operation input if it falls below the increased touch detection threshold. There was a problem of being there.

  The present invention solves the above-described problems, and an object of the present invention is to provide a capacitance-type input device that can prevent erroneous detection even when noise occurs.

  In order to solve this problem, the input device of the present invention has a plurality of capacitance detection units, the input unit that the operating body performs a proximity operation, and the capacitance is measured and measured for each capacitance detection unit. A capacitance measuring unit that outputs a capacitance value as data, the capacitance value is acquired in association with the capacitance detection unit, a base value is updated using the capacitance value, and the capacitance value And a control unit that detects whether or not an operation is performed by determining whether or not a difference between the base value and the base value exceeds a predetermined threshold value, and the control unit determines whether the capacitance value and the base value are The presence / absence of noise is determined from the difference, and when it is determined that there is no noise, the base value is set as the first weight as the weighted average calculation weight, and when it is determined that there is noise, Greater than the first weight as the weight of the weighted average calculation for updating the base value Set to the second weight, or wherein the stop updating.

  According to this, since the base value does not follow the noise even if noise is added, it is possible to prevent false detection when the noise is removed. A capacitive input device can be provided.

  In the input device of the present invention, when the control unit determines that the operation is valid, the control unit sets the second weight as the weight of the weighted average calculation for updating the base value, or stops the update. It is characterized by.

  According to this, when the control unit determines that there is an operation, the second weight is set or the update is stopped, so that the base value does not follow the capacity change due to the operation, so the input operation is reliably detected. be able to.

  In the input device of the present invention, when the control unit detects an operation to the input unit, the maximum difference between the capacitance values output from the plurality of capacitance detection units and the base value is determined. It is determined that the operation is valid when the value and the minimum value satisfy a predetermined condition, and the second weight is set as the weight of the weighted average calculation for updating the base value, or the update is stopped And

  According to this, by taking the ratio between the maximum value and the minimum value of the difference between the capacitance value and the base value, the contact operation in which the ratio between the minimum value and the maximum value is increased, and the ratio between the maximum value and the minimum value is A small noise can be more reliably discriminated. For this reason, it is possible to provide an input device that can further reduce erroneous detection.

  In the input device of the present invention, when the control unit detects an operation to the input unit when it detects that the sum of the difference between the capacitance value and the base value has changed due to noise. Whether the operation is valid or not is determined, and when the operation is determined to be invalid, the first weight is set as the weight of the weighted average calculation for updating the base value.

  According to this, when an operation is detected based on a change in noise and the operation input is determined to be invalid, the first weight is set as the weight of the weighted average calculation for updating the base value. The deviation between the capacitance value and the base value due to can be eliminated in a short time.

  Further, the input device of the present invention is characterized in that the update of the base value is obtained by a weighted average calculation represented by the following equation (1).

(Equation 1)
Update base value = (p × conventional base value + q × average value of difference between capacitance value and base value) / (p + q) (1)
However, p and q are positive numbers indicating weights, and p + q ≧ 1.

  According to this, the speed at which the base value follows easily can be changed by the values of the weights p and q. For this reason, it is possible to easily set the weighted average weight according to the environment used such as temperature and noise.

  According to the present invention, it is possible to provide a capacitance type input device capable of preventing erroneous detection even when noise occurs.

It is a block diagram which shows the structure of the input device which concerns on embodiment of this invention. 1 is a schematic external view of an input device according to an embodiment of the present invention. It is a flowchart which shows the operation | movement outline | summary of the input device which concerns on embodiment of this invention. It is a flowchart which shows the detailed process sequence of procedure S1 of FIG. It is a flowchart which shows the detailed process sequence of procedure S2 of FIG. It is a flowchart which shows the detailed process sequence of procedure S3 of FIG. It is a block diagram which shows the structure of the input device of a prior art. It is a figure explaining operation | movement of the input device of a prior art.

[First Embodiment]
The input device 100 according to the first embodiment will be described below.

  First, the configuration of the capacitance-type input device 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing the configuration of the input device 100, and FIG. 2 is a schematic external view of the input device 100.

  As shown in FIG. 1, the input device 100 includes an input unit 1, a capacity measurement unit 2, and a control unit 3. The input unit 1 is connected to the capacity measuring unit 2, and the capacity measuring unit 2 is connected to the control unit 3. The control unit 3 is configured to be connectable to the external device 50.

  As shown in FIG. 2, the input unit 1 performs an input operation by a proximity operation in which an operation body 60 such as an operator's finger approaches or touches the input operation surface. In the input unit 1, a plurality of capacitance detection units 1 a are arranged in a matrix along the input operation surface in the X direction and N in the Y direction orthogonal to the X direction (M and N are natural numbers). To do)

  The capacitance detection unit 1a has a capacitance, and when an operator touches the input unit 1 with an operation body 60 such as a finger in order to perform an input operation, the capacitance detection unit 1a at and near the contacted position. The capacitance of changes. In the present embodiment, the description will be made assuming that the capacitance increases when the operating body 60 comes into contact.

  The capacitance measurement unit 2 measures the capacitance of each of the plurality of capacitance detection units 1a, and performs Analog-to-Digital conversion (hereinafter referred to as AD conversion) for converting the measured capacitance from an analog signal to a digital signal. . Further, the capacitance measuring unit 2 outputs the capacitance value converted into a digital signal by AD conversion to the control unit 3 as data.

  The control unit 3 controls the capacitance measuring unit 2 to acquire the capacitance value for each of the plurality of capacitance detection units 1a in association with the coordinate information of the capacitance detection unit 1a. The control unit 3 calculates using the capacitance value acquired in association with the coordinate information from the capacitance measuring unit 2, and outputs a control signal to the external device 50 based on the result. Further, the control unit 3 is provided with a timer function and a memory (not shown) to manage the control interval by the timer function and store the acquired capacitance value and the result of calculating the capacitance value. It can be carried out.

  Next, the operation of the input device 100 in the first embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing an outline of the operation of the input device 100 according to the first embodiment. The processing procedure shown in the flowchart of FIG. 3 is periodically repeated by a timer function or the like built in the control unit 3.

  First, in step S1, the control unit 3 controls the capacitance measurement unit 2 to acquire the capacitance value for each capacitance detection unit 1a, and the memory included in the control unit 3 in accordance with the coordinate information of the capacitance detection unit 1a. The storage area for the capacitance value is set and stored. In addition, the control unit 3 determines whether the difference between the acquired capacitance value and the base value exceeds a predetermined threshold value, and detects the presence or absence of noise or an operation. When the operation is detected, the control unit 3 determines whether the operation is valid / invalid or the presence / absence of noise from the difference between the capacitance value and the base value, and stores the result in the memory. The base value is obtained by weighted averaging the capacitance values of the capacitance detection unit 1a, and the capacitance detection unit 1a in a state where the operation body 60 such as the operator's finger is not in proximity to or in contact with the input operation surface. Treat it as a capacitance value. Therefore, the difference between the capacitance value and the base value indicates the amount of change in the capacitance value due to an input operation or noise intrusion.

  Next, in step S2, the control unit 3 calculates the difference between the capacitance value obtained in step S1 and the base value, and calculates the noise state and the base value generated when the noise state changes. The presence / absence of occurrence of erroneous detection due to fluctuation is determined, and the result is stored in the memory.

  In step S3, the control unit 3 outputs a control signal corresponding to the presence / absence of an operation and sets a weighted average weight based on the results determined in step S1 and step S2, and uses the acquired capacitance value as a base. Update the value (BASE). The updated base value is stored in a memory included in the control unit 3 by setting a recording area for noise information and a storage area for the base value (BASE).

  Next, the processing from step S1 to step S3 shown in the flowchart of FIG. 3 will be described in detail with reference to FIGS.

  FIG. 4 is a flowchart showing a detailed processing procedure of procedure S1 of the flowchart shown in FIG. Note that the threshold value and base value (BASE) necessary for performing calculations according to the procedure of the flowchart are set in advance in the control unit 3 by appropriately setting the values and initial values according to the device to be incorporated and the assumed usage state. It is assumed that it is stored in the memory.

  In step S1_1 shown in the flowchart of FIG. 4, the control unit 3 sets a noise flag indicating the result of determining the presence or absence of noise to 0 indicating no noise as an initial state, stores the noise flag in the memory, and stores the result in step S1_2. Migrate to

  In step S1_2, the control unit 3 sequentially acquires the capacitance value C (x, y) from the capacitance measurement unit 2 for all the capacitance detection units 1a. The acquired capacitance value C (x, y) is set in correspondence with the coordinate information (x, y) of the capacitance detection unit 1a, and a capacitance value storage area is set in the memory included in the control unit 3. It memorize | stores and transfers to procedure S1_3. The coordinate information (x, y) of the capacitance detection unit 1a is represented by (m, n) when a certain capacitance detection unit 1a is at the mth position in the X direction and the nth position in the Y direction. Is expressed as C (m, n). Note that x is represented by a natural number from 1 to M, and y is represented by a natural number from 1 to N.

  In step S1_3, the control unit 3 calculates the difference between the capacitance value C (x, y) acquired in step S1_2 and the base value (BASE) stored in the memory. The calculated value is set as a capacity change value ΔC (x, y), corresponding to the coordinate information (x, y) of the capacity detection unit 1a, and a storage area for the capacity change value is set in the memory included in the control unit 3. It memorize | stores and transfers to procedure S1_4.

  In step S1_4, the control unit 3 extracts a capacity change value ΔCL (x, y) that maximizes the capacity change value ΔC (x, y) obtained in step S1_3, and obtains the value and coordinate information (x, y). Store and move to step S1_5.

  In step S1_5, the control unit 3 extracts a capacity change value ΔCS (x, y) that minimizes the capacity change value ΔC (x, y) obtained in step S1_3, and obtains the value and coordinate information (x, y). Store and move to step S1_6.

  In step S1_6, the control unit 3 determines that the capacitance change value ΔCL (x, y) extracted in step S1_4 and the capacitance change value ΔCL (x, y) are significantly different from changes due to an environment such as temperature or an error in AD conversion. A signal input determination threshold Th1 for determining the presence / absence of capacitance change is compared. If the capacitance change value ΔCL (x, y) is equal to or greater than the signal input determination threshold Th1, it is determined that a change has occurred in the capacitance value C (x, y), and the process proceeds to step S1_7. If the capacitance change value ΔCL (x, y) is less than the signal input determination threshold Th1, it is determined that there is no change in the capacitance value C (x, y), and the process proceeds to step S1_16.

  In step S1_7, the control unit 3 compares the capacitance change value ΔCL (x, y) extracted in step S1_4 with the operation determination threshold Th2 that is set to a value larger than the signal input determination threshold Th1 and determines whether there is an input operation. . When the capacitance change value ΔCL (x, y) is equal to or greater than the operation determination threshold Th2, it is determined that there has been an operation, and the process proceeds to step S1_8. If the capacity change value ΔCL (x, y) is less than the operation determination threshold Th2, it is determined that there is no operation, and the process proceeds to step S1_15. The operation determination threshold Th2 is used to determine whether there is a change in capacity.

  In step S1_8, the control unit 3 integrates the value of the capacitance change value ΔC (x, y) having a negative value from the capacitance change value ΔC (x, y) obtained in step S1_3, and obtains the obtained value as ΣΔC (− ) And the process proceeds to step S1_9.

  In step S1_9, the control unit 3 compares the value of ΣΔC (−) obtained in step S1_8 with the noise determination threshold Th3. If the value of ΣΔC (−) is greater than the noise determination threshold Th3 (the absolute value is small), it is determined that there is little influence on the capacitance change value ΔC (x, y) due to noise and there is no false detection, and the procedure goes to step S1_10. Transition. Further, when the value of ΣΔC (−) is equal to or less than the noise determination threshold Th3 (the absolute value is large), it is determined that the influence on the capacitance change value ΔC (x, y) due to noise is large and there is a false detection. Control goes to step S1_14.

  In step S1_10, the control unit 3 sets the capacitance change value ΔCL (x, y) that maximizes the absolute value obtained in step S1_4 to the capacitance change value ΔCS (x, y) that minimizes the absolute value obtained in step S1_5. The ratio CR is obtained, the result is stored in the memory, and the process proceeds to step S1_11.

  In step S1_11, the control unit 3 compares the capacitance ratio CR obtained in step S1_11 with the first validity determination threshold Th4 for determining whether the contact operation is valid or invalid. If the capacitance ratio CR is greater than or equal to the first validity determination threshold Th4, it is determined that the operation is valid, and the process proceeds to step S1_13. If the capacitance ratio CR is less than the first validity determination threshold Th4, the process proceeds to step S1_12.

  In step S1_12, the control unit 3 compares the capacitance change value ΔCL (x, y) having the maximum absolute value obtained in step S1_4 with the second validity determination threshold Th5 for determining whether the contact operation is valid or invalid. If the capacitance change value ΔCL (x, y) that maximizes the absolute value is equal to or greater than the second validity determination threshold Th5, it is determined that the operation is valid, and the process proceeds to step S1_13. If the capacitance change value ΔCL (x, y) that maximizes the absolute value is less than the second validity determination threshold Th5, it is determined that the operation is invalid, and the process proceeds to step S1_14.

  As described above, when the control unit 3 detects an operation to the input unit in step S1_7, the capacitance value C (x, y) and the base value (BASE) output from the plurality of capacitance detection units 1a. The maximum value ΔCL (x, y) and the minimum value ΔCS (x, y) of the capacitance change value ΔC (x, y) that is the difference between the values satisfy the predetermined condition determined in the steps S1_10 and S1_11. If it is determined that the operation is valid.

  In step S1_13, the control unit 3 sets 0 indicating that there is no false detection in the false detection flag indicating whether there is a false detection, and indicates that there is a valid operation in the operation flag indicating the presence of a valid operation. Is set, each flag is stored in the memory, and the operation of step S1 is terminated.

  The process proceeds to step S1_14 when it is determined that there is a false detection in step S1_9, and the capacity change value ΔCL (x, y) at which the absolute value is maximum in step S1_12 is less than the second validity determination threshold Th5. This is a case where the operation is determined to be invalid. Therefore, the control unit 3 sets 1 indicating that there is a false detection in the false detection flag indicating whether there is a false detection, and sets 0 indicating that there is no valid operation to the operation flag indicating whether there is a valid operation. Then, each flag is stored in the memory, and the operation of step S1 is completed.

  The process proceeds to step S1_15 when it is determined in step S1_6 that the capacitance value C (x, y) has changed, and in step S1_7 it is determined that there has been no operation. Therefore, the control unit 3 determines that the input is noise, sets 1 indicating that noise is present in the noise flag indicating presence / absence of noise, stores the noise in the memory, and proceeds to step S1_16.

  The process moves to step S1_16 when it is determined in step S1_6 that there is no change in the capacitance value C (x, y), or when it is determined that there is no operation in step S1_7. . Therefore, the control unit 3 sets 0 indicating that there is no false detection in the false detection flag indicating whether there is a false detection, and sets 0 indicating that there is no valid operation to the operation flag indicating whether there is a valid operation. Thus, the respective flags are stored in the memory, and the operation of step S1 is completed.

  FIG. 5 is a flowchart showing a detailed processing procedure of step S2 of the flowchart shown in FIG.

  In step S2_1 shown in the flowchart of FIG. 5, the control unit 3 determines the mode value indicating the erroneous detection determination state. If 0, the process proceeds to step S2_2. If 1 the process proceeds to step S2_5. If so, the process proceeds to step S2_8. If 3, the process proceeds to step S2_14. The initial value of the mode is set to 0 indicating a normal state where the input operation can be normally performed. A mode value of 1 indicates a state in which a false detection due to the influence of noise may occur, a case of 2 indicates a state in which an operation input is detected or a false detection, and a case of 3 indicates an operation. Or it shows a state where there is no input due to erroneous detection.

  The process proceeds to step S2_2 when the mode value is 0 indicating a normal state in which the input operation can be normally performed in step S2_1. In step S2_2, the control unit 3 adds up all the capacity change values ΔC (x, y) obtained in step S1_3, calculates the total value ΣΔC of the capacity change as a sum, stores it in the memory, and proceeds to step S2_3.

  In step S2_3, the control unit 3 compares the total capacitance change value ΣΔC obtained in step S2_2 with a capacitance change threshold Th6 that determines whether or not there is a change in overall capacitance value due to noise. If the total value ΣΔC of the capacity change is equal to or smaller than the capacity change threshold Th6, it is determined that there is a change in the overall capacity value, and the process proceeds to step S2_4. It is determined that there is no change, and the operation of step S2 is terminated.

  In step S2_4, the control unit 3 sets the mode value to 1 indicating a state in which erroneous detection due to the influence of noise may occur, stores the value in the memory, and ends the operation of step S2.

  The process proceeds to step S2_5 when the mode value is 1 in step S2_1 indicating a state in which a false detection due to the influence of noise may occur. In step S2_5, the control unit 3 compares the capacitance change value ΔCL (x, y) extracted in step S1_4 with the operation determination threshold value Th2 for determining the presence or absence of an input operation, and the capacitance change value ΔCL (x, y) is obtained. If it is greater than or equal to the operation determination threshold Th2, it is determined that there has been an operation or erroneous detection, and the process proceeds to step S2_6. On the other hand, if the capacitance change value ΔCL (x, y) is less than the operation determination threshold Th2, it is determined that there has been no operation or erroneous detection, and the operation of step S2 is terminated.

  In step S2_6, the control unit 3 sets the mode value to 2 indicating a state in which an operation input is detected or erroneously detected, stores the value in the memory, and proceeds to step S2_7.

  In step S2_7, the control unit 3 sets the fake finger flag indicating that the operation due to the erroneous detection is detected to 0 indicating the state where the operation due to the erroneous detection is not detected, and stores it in the memory, and ends the operation of the step S2. To do.

  The process proceeds to step S2_8 when the mode value is 2 in step S2_1 indicating a state in which an operation input is detected or erroneously detected. In step S2_8, the control unit 3 compares the capacitance change value ΔCL (x, y) extracted in step S1_4 with the operation determination threshold Th2 for determining the presence or absence of an input operation, and the capacitance change value ΔCL (x, y) is obtained. If it is less than the operation determination threshold Th2, it is determined that there is no operation or erroneous detection, and the process proceeds to step S2_9. When the capacity change value ΔCL (x, y) is equal to or greater than the operation determination threshold value Th2, it is determined that there is an operation or erroneous detection, and the process proceeds to step S2_12.

  In step S2_9, the control unit 3 sets the mode value to 3 indicating that there is no input due to operation or erroneous detection, stores the value in the memory, and proceeds to step S2_10.

  In step S2_10, the control unit 3 sets the timer to 0 in the initial state, starts counting, and proceeds to step S2_11.

  In step S2_11, the control unit 3 sets 0 indicating that the operation due to the erroneous detection is not detected in the fake finger flag indicating that the operation due to the erroneous detection is detected, and stores it in the memory, and ends the operation of step S2. To do.

  The process proceeds to step S2_12 when it is determined in step S2_8 that there is an operation or a false detection. In step S2_12, the control unit 3 determines the value of a false detection flag indicating the presence or absence of false detection. If the false detection flag is set to 1, the control unit 3 proceeds to step S2_13. On the other hand, when the erroneous detection flag is set to 0, the operation in step S2 is terminated.

  In step S2_13, the control unit 3 sets 1 indicating the state in which the operation due to the erroneous detection is detected to the fake finger flag indicating that the operation due to the erroneous detection has been detected, and stores it in the memory, and ends the operation of step S2.

  The process proceeds to step S2_14 when the mode value is 3 in step S2_1 indicating that there is no input due to operation or erroneous detection. In step S2_12, the control unit 3 determines whether the timer value has passed the predetermined time T. If the timer value is less than the predetermined time T, the control unit 3 proceeds to step S2_15. On the other hand, if the predetermined time T has elapsed, the process proceeds to step S2_18.

  In step S2_15, the control unit 3 compares the capacitance change value ΔCL (x, y) extracted in step S1_4 with the operation determination threshold value Th2 for determining whether or not there is an input operation. If the capacitance change value ΔCL (x, y) is equal to or greater than the operation determination threshold Th2, it is determined that there has been an operation or erroneous detection, and the process proceeds to step S2_16. If it is less than the operation determination threshold Th2, there has been no operation or erroneous detection. It is determined that the operation of step S2 is finished.

  In step S2_16, the control unit 3 sets the mode value to 2 indicating a state in which the operation input is detected or erroneously detected, stores the value in the memory, and proceeds to step S2_17.

  In step S2_17, the control section 3 stores 0 in the fake finger flag indicating that an operation due to a false detection has been detected, indicating that no operation due to a false detection has been detected, and stores the result in the memory. To do.

  The process proceeds to step S2_18 when the timer has passed the predetermined time T in step S2_14. Since the state in which there is no input due to an operation or erroneous detection has elapsed for a certain time T, it is determined that the input state can be normally performed, and the control unit 3 sets the mode value to 0 and stores it in the memory. Then, the operation of step S2 is terminated.

  As described above, when the control unit 3 detects that the total value ΣΔC of the capacitance change, which is the sum of the difference between the capacitance value and the base value, is changed due to noise in step S2_3, the control unit 3 sets the mode in step S2_4. Switch to. When an operation to the input unit is detected in step S2_5, the mode is switched to 2 in step S2_6. In step S2_8 and step S2_12, it is determined whether or not the operation is valid. If it is determined that the operation is invalid, an operation due to the false detection is detected in the fake finger flag indicating that the operation due to the false detection is detected in step S2_13. 1 is set to indicate the status.

  FIG. 6 is a flowchart showing a detailed processing procedure of step S3 of the flowchart shown in FIG.

  The control unit 3 determines the value of the operation flag in step S3_1 shown in the flowchart of FIG. If 1 indicating that the operation is determined to be valid is set in the operation flag, the process proceeds to step S3_2. If 0 indicating that no operation is valid is set, step S3_5 is performed. Migrate to

  In step S3_2, the control unit 3 outputs a control signal corresponding to the coordinate information (x, y) of the capacity change value ΔCL (x, y) extracted and stored in step S1_4, and proceeds to step S3_3.

  In step S3_3, the control unit 3 sets 0 indicating that the update of the base value (BASE) is stopped to the weight (Weight) of the weighted average calculation for updating the base value, and proceeds to step S3_4. When updating of the base value (BASE) is stopped, it is equivalent to setting the weighted weight (Weight) to infinity, and the current base is set until a specific value is set for the weighted weight (Weight). The value (BASE) is maintained.

  In step S3_4, the control unit 3 determines the value of the weighted average calculation weight (Weight) and ends the operation of step S3 when 0 is set, and when a value other than 0 is set. Control goes to step S3_10.

  The process moves to step S3_5 when 0 is set in the operation flag value indicating that there is no effective operation in step S3_1. In step S3_5, the control unit 3 outputs a control signal corresponding to no input, and proceeds to step S3_6.

  In step S3_6, the control unit 3 determines the value of the fake finger flag indicating that an operation due to erroneous detection has been detected. If the fake finger flag is set to 0, the process proceeds to step S3_7 and 1 is set. If yes, the process proceeds to step S3_9.

  In step S3_7, the control unit 3 determines the value of the noise flag indicating the presence or absence of noise. If 1 is set in the noise flag, the process proceeds to step S3_8, and if 0 is set, step S3_9. Migrate to

The process moves to step S3_8 when it is determined that there is no effective operation in step S3_1, no operation due to erroneous detection is detected in step S3_6, and noise is input in step S3_7. For this reason, the control unit 3 sets the second weight 16 larger than the first weight as the weight (Weight) of the weighted average calculation for updating the base value, and proceeds to step S3_4. In the present embodiment, when the weight of the average weight (Weight) is set to 16, the weight p for the base value (BASE) before being updated is 15 so that the total number of weights p + q is 16. Assume that 1 is assigned to the weight q for the average value ΔCv of the difference between the capacitance value and the base value. Further, the weight p and the weight q are used in Equation (1) for obtaining a weighted average described later.

  The procedure moves to step S3_9 because there is no effective operation in step S3_1 and an operation due to a false detection is detected in step S3_6, or an operation due to a false detection is not detected in step S3_6 and no noise is detected in step S3_7. This is a case where it is determined that no input has been made. Therefore, the control unit 3 sets a standard value (2 in the present embodiment) as the first weight as the weight (Weight) of the weighted average calculation for updating the base value, and proceeds to step S3_4. In the present embodiment, when the weight of the average weight (Weight) is set to 2, the weight p for the base value (BASE) before being updated is set to 1 so that the total weight p + q is 2. Assume that 1 is assigned to the weight q for the average value ΔCv of the difference between the capacitance value and the base value.

  The process moves to step S3_10 when a value other than 0 is set as the weight (Weight) value of the weighted average calculation in step S3_4. In step S3_10, the control unit 3 updates the base value (BASE) using the weighted average weight set in either step S3_8 or step S3_9. For updating the base value (BASE), a weighted average calculation is performed using the calculation formula shown in the following formula (1) to obtain an updated base value (N_BASE) as a new reference value, and the process proceeds to step S3_11. The average value of the difference between the capacitance value and the base value is ΔCv, which is obtained by integrating all the capacitance change values ΔC (x, y) obtained in step S1_3 to obtain the total capacitance change value ΣΔC of the total number of capacitance detectors 1a ( The value is divided by (M × N). The base value (BASE) before being updated is described as a conventional base value.

(Equation 2)
Update base value = (p × conventional base value + q × average value of difference between capacitance value and base value) / (p + q) (1)
However, p and q are positive numbers indicating weights, and p + q ≧ 1.

  In step S3_11, the control unit 3 stores the update base value (N_BASE) obtained in step S3_10 as a reference value (BASE), and ends the operation of step S3.

  Hereinafter, the effect by having set it as this embodiment is demonstrated.

  In the input device 100 of the present embodiment, the control unit 3 determines the presence / absence of noise from the difference between the capacitance value C (x, y) and the base value (BASE), and determines that there is no noise. , The weight (Average) for updating the base value (BASE) is set as the first weight (Weight), and when it is determined that there is noise, the weight for the weighted average calculation (BASE) for updating the base value (BASE) ( The weight is set to a second weight greater than the first weight.

  As a result, when the capacitance value C (x, y) is reduced due to noise, the base value (BASE) is updated more slowly and it becomes difficult to follow the noise. For this reason, when noise is removed, even if the capacitance value C (x, y) returns to the original state, the difference between the capacitance value C (x, y) and the base value (BASE) It can be reduced that a certain capacitance change value ΔC (x, y) exceeds the signal input determination threshold Th1 and the operation determination threshold Th2. In this way, by changing the weight (Weight) of the weighted average calculation for updating the base value (BASE), the speed at which the base value (BASE) is updated is delayed, thereby causing the noise state to fluctuate. The occurrence of false detection can be reduced. Therefore, it is possible to provide a capacitance type input device capable of preventing erroneous detection even when noise occurs.

  Further, in the input device 100 of the present embodiment, the control unit 3 is configured to stop updating (BASE) to the base value when it is determined that the operation is valid.

  Thus, since the base value (BASE) is not updated while the operation is determined to be valid, the base value (BASE) does not follow the capacity change caused by the operation, and thus the input operation can be reliably detected.

  Moreover, in the input device 100 of this embodiment, when the control part 3 detects operation to an input part, the electrostatic capacitance value C (x, y) and base value which are output from the some capacitance detection part 1a are detected. When the maximum value ΔCL and the minimum value ΔCS of the capacity change value ΔCL (x, y), which is the difference from (BASE), satisfy a predetermined condition, the operation is determined to be valid, and the base value (BASE) is updated. Configured to stop.

  As a result, a contact operation in which the change in capacitance is stable and the ratio of the maximum value ΔCL and the minimum value ΔCS of the capacitance change value ΔCL (x, y) increases, and noise that becomes smaller due to an irregular change, Can be determined more reliably. For this reason, it is possible to provide an input device that can further reduce erroneous detection.

  Further, in the input device 100 of the present embodiment, the control unit 3 causes the total value ΣΔC of the capacitance change, which is the sum of the differences between the capacitance value C (x, y) and the base value (BASE), to change due to noise. When an operation to the input unit is detected, it is determined whether or not the operation is valid. When the operation is determined to be invalid, a weighted average calculation is performed to update the base value (BASE). The first weight is set as the weight (Weight).

  Accordingly, when it is erroneously detected that there is an operation due to a change in noise and it is determined that the operation input is invalid, the first weight is set as the weight of the weighted average calculation for updating the base value. Deviation between the capacitance value and the base value due to input can be eliminated in a short time.

  In the input device 100 of the present embodiment, the weighted average calculation is configured to be obtained by the above equation (1).

  Thereby, the speed with which the base value follows easily can be changed by the values of the weights p and q. For this reason, it is possible to easily set the weighted average weight according to the environment used such as temperature and noise.

  As described above, the input device according to the embodiment of the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the invention. Is possible. For example, the present invention can be modified as follows, and these embodiments also belong to the technical scope of the present invention.

  (1) In the present embodiment, noise is detected when the capacitance change value ΔCL (x, y) is not less than the signal input determination threshold Th1 (procedure S1_6) and less than the operation determination threshold Th2 (procedure S1_6). Although the description has been made with reference to an example in which it is determined that noise has occurred, noise may be determined by other means. For example, the capacitance values of at least one predetermined capacitance detection unit 1a may be acquired a plurality of times in a short period, and the presence or absence of noise may be determined from the temporal change. Moreover, noise is obtained by comparing the capacitance value of one capacitance detection unit 1a with the capacitance value of the capacitance detection unit 1a of the capacitance detection unit 1a arranged around the capacitance detection unit 1a. It may be determined whether or not there is.

  (2) In the present embodiment, when noise is detected, the weighted average calculation weight (Weight) is set to the second weight larger than the first weight. The value (BASE) may be changed and stopped to be updated.

  (3) In the present embodiment, when the operation is determined to be valid, the update of the base value (BASE) has been described with an example of stopping, but the weight (Weight) of the weighted average calculation is set to the first It may be implemented by changing to update the base value by setting the second weight larger than the weight.

  (4) In the present embodiment, the weighted average calculation weight (Weight) has been described with specific numerical values, but the value may be changed as appropriate according to the device to be incorporated and the assumed usage state. . Also, the numerical values may be changed and modified according to changes in ambient temperature, operating environment, and the like.

  (5) In the present embodiment, the operation has been described using an example in which noise removal processing and smoothing processing are not performed on the acquired capacitance value C (x, y). Alternatively, a smoothing process may be performed.

  (6) In the present embodiment, the example in which the equation for obtaining the weighted average is obtained by the equation (1) has been described. However, when the value of q is limited to 1 in the equation (1), the equation ( 1) can be carried out by modifying the following equation (2). In this case, the expression (1) corresponds to (p-1) in the expression (2), and (p + q) in the expression (1) corresponds to p in the expression (2). In this case, the weighted average weight can be determined more easily by determining the value of p.

(Equation 3)
Update base value = {(p−1) × conventional base value + average value of difference between capacitance value and base value} / p (2)
Here, p is a positive number indicating the weight.

DESCRIPTION OF SYMBOLS 1 Input part 1a Capacity | capacitance detection part 2 Capacity | capacitance measurement part 3 Control part 50 External apparatus 60 Operation body 100 Input device

Claims (5)

An input unit having a plurality of capacitance detection units, and the operation body performing a proximity operation;
A capacitance measuring unit that measures the capacitance for each capacitance detection unit and outputs the measured capacitance value as data;
Acquiring the capacitance value in association with the capacitance detector, updating the base value using the capacitance value,
A capacitance type input device having a control unit that determines whether or not the difference between the capacitance value and the base value exceeds a predetermined threshold value,
The control unit determines the presence or absence of noise from the difference between the capacitance value and the base value,
If it is determined that there is no noise, set the first weight as a weighted average calculation weight for updating the base value,
When it is determined that there is noise, an input device is characterized in that the second weight larger than the first weight is set as a weighted average calculation weight for updating the base value, or updating is stopped.   2. The control unit according to claim 1, wherein when the operation is determined to be valid, the control unit sets the second weight as a weighted average calculation weight for updating the base value or stops the update. Input device.   When the control unit detects an operation to the input unit, a maximum value and a minimum value of a difference between the capacitance value output from the plurality of capacitance detection units and the base value are predetermined conditions. 3. The input device according to claim 2, wherein the operation is determined to be valid when the condition is satisfied, and the second weight is set as a weight of a weighted average calculation for updating the base value, or the update is stopped. . When the control unit detects an operation to the input unit when detecting that the sum of the difference between the capacitance value and the base value has changed due to noise,
The first weight is set as a weight of a weighted average calculation for updating the base value when it is determined whether or not the operation is valid and the operation is determined to be invalid. The input device according to claim 3. The input device according to claim 1, wherein the update of the base value is obtained by a weighted average calculation represented by the following equation (1).
Update base value = (p × conventional base value + q × average value of difference between capacitance value and base value) / (p + q) (1)
However, p and q are positive numbers indicating weights, and p + q ≧ 1.