JP6115888B2 - Capacitive touch sensor - Google Patents

Description

  The present invention relates to a capacitive touch sensor, and more particularly, to a capacitive touch sensor using a synchronous inversion integration method.

  Conventionally, so-called push buttons have been generally used for operation units of electronic devices such as remote controllers, audio devices, game machines, and mobile phones. The push button monitors the contact / non-contact of the contact point of the mechanical switch. However, in recent years, a capacitive touch sensor has been increasingly mounted on an operation unit. The capacitive touch sensor has a higher degree of design freedom than a mechanical switch and is excellent in durability. Furthermore, since the capacitive touch sensor can be mounted in a hermetically sealed casing, it has excellent water resistance.

  The capacitive touch sensor detects a change in electrostatic capacitance around the electrode due to the proximity of a human body (usually a fingertip) of a user of the electronic device to detection electrodes (transmission electrode and reception electrode). For this reason, in the capacitive touch sensor, a detection signal is applied to the transmission electrode, a reception signal generated by applying the detection signal is received by the reception electrode, and detection processing is performed based on the reception signal. For example, a synchronous inversion integration method is known as one method of a capacitive touch sensor (see Patent Document 1).

JP 2009-287993 A

  In an electric device, the operation unit is not always operated by the user, and a state where the operation unit is not operated (that is, a standby state) is significantly longer. However, in the capacitive touch sensor, in order to detect that the user performs a touch operation or a proximity operation on the electrode, it is necessary to always operate the capacitance detection circuit and continuously perform the detection process. Therefore, even when the operation unit of the electronic device is not operated, the capacitive touch sensor always consumes power, so that there is a problem that power consumption is larger than that of the mechanical switch.

  In addition, in order to quickly shift the electronic device from the standby state to the operating state, it is necessary to shorten the detection cycle of the capacitive touch sensor. Further, when the touch sensor has a plurality of electrodes (a plurality of operation switches), the number of detection processes increases in proportion to the number of electrodes, so that standby power consumption also increases. This increase in standby power consumption becomes a serious problem especially for electronic devices using a battery as a power source.

  For example, in the case of a remote controller for a warm water flush toilet seat, a dry battery is often used as a power source so that it can be freely attached to an easily operable position in the toilet. This remote control is provided with switches for various functions. Specifically, "stop", "wet washing", "bidet washing", "warm air drying", "wet soft washing", "bide wide washing", "toilet large washing", "toilet small washing", "toilet seat" These are switches such as “open / close” and “stool lid open / close”. Among these, a capacitive touch sensor is used for a plurality of switches.

  For example, when the operation unit includes 10 touch sensors, if the detection cycle is 0.1 sec (that is, the detection frequency is 10 Hz), the detection processing time (operation time) of one touch sensor is 10 msec. Even so, the operation time of the detection circuit per second is “10 msec × 10 × 10 Hz = 1 sec”. That is, the capacitance detection circuit always operates. As a result, the amount of power consumption increases and the dry battery as a power source is consumed in a short period of time.

  In order to solve this problem, a method of reducing power consumption by shortening the detection processing time of the capacitance detection circuit per touch sensor can be considered. However, since the change in the capacitance of the touch sensor is extremely small, it takes time to perform detection processing to eliminate external noise and realize touch detection without malfunction. It is difficult to simply shorten.

  In the synchronous inversion integration type touch sensor described in Patent Document 1, the output of the amplifying means connected to the receiving electrode and the inverted output in which the polarity is inverted are alternately synchronized with the transmission signal (transmission pulse). Therefore, noise components that are not synchronized with the transmission signal can be removed. However, if the detection processing time is shortened, the power consumption can be reduced, but at the same time, the integration time is also shortened, so that the effect of noise removal is also reduced and the possibility of erroneous detection occurs. As described above, in the method of shortening the detection processing time, it is difficult to greatly reduce power consumption, and further, there is a risk of erroneous detection.

  In order to solve the above problem, a method of simultaneously applying a transmission pulse to a plurality of transmission electrodes and simultaneously integrating the reception signals from the reception electrodes can be considered. However, the operation of the detection circuit has a dynamic range limitation determined by the circuit configuration and the power supply voltage. That is, if integration is performed for a plurality of electrodes simultaneously, the integration value increases in accordance with the number of electrodes, and this integration value may exceed the dynamic range. In order to avoid this, it is necessary to take measures in the direction of increasing noise, such as shortening the integration time, resulting in the possibility of erroneous detection.

  Furthermore, when integration is performed for a plurality of electrodes at the same time, the change in the integration value due to the touch of one electrode is only the ratio of one electrode to the plurality of electrodes. For this reason, when the number of electrodes increases, the rate of change decreases, and detection becomes difficult.

  In addition, the capacitance of the electrode changes due to changes in the use environment and manufacturing variations. Therefore, the change in the integral value due to the touch of one electrode is different for each electrode. Therefore, if the presence / absence of a touch is determined using a simple threshold, there is a risk of erroneous detection.

  Note that reduction of standby power consumption is an important issue even in electronic devices that operate with AC power from a power plug instead of a dry battery. For this reason, in an electronic device driven by an AC power source, for example, a power circuit such as a switching power supply is stopped during standby, and power consumption is reduced by using an internal battery or a large-capacitance capacitor, thereby reducing standby power consumption of the electronic device. A scheme has been proposed. Such electronic devices consume substantially zero watts during standby.

  As described above, reducing the standby power consumption of the operation unit is an important issue not only in electronic devices using a battery as a power source but also in all electronic devices. For this reason, the power consumption required for the detection operation of the capacitive touch sensor hinders the adoption of the capacitive touch sensor in the operation unit of the electronic device. In particular, it has been difficult to adopt a touch sensor in a remote control using a dry battery as a power source and having a large number of operation switches.

  The present invention has been made to solve such a problem. In a capacitive touch sensor having a plurality of electrodes, the power consumption during standby and during operation is greatly reduced and false detection is performed. It is an object of the present invention to provide a capacitive touch sensor that can suppress the occurrence of the above.

In order to solve the above-described problem, the present invention includes a pulse output unit that outputs a pulse signal having a predetermined frequency, and a transmission electrode and a reception electrode that are arranged in close proximity to each other and are electrostatically coupled. A detector configured to output an induced voltage output by the receiving electrode when a pulse signal is applied; an amplifying unit that amplifies the induced voltage output received from the receiving electrode and outputs an amplified output; and Inverting means for inverting the polarity of the amplified output received from the amplifying means and outputting an inverted output; and the amplified output and the inverted output are alternately selected in synchronization with the pulse signal and integrated to output an integrated output An electrostatic capacitance type touch sensor comprising: an integrating unit; and a determining unit that determines proximity of the human body to the detecting unit based on an integrated output received from the integrating unit. The plurality of reception electrodes constituting the plurality of detection units are electrically connected to each other, and the pulse output means applies the pulse to each of the plurality of transmission electrodes constituting the plurality of detection units. A second output mode in which a first transmission pulse signal having a phase substantially the same as the signal is applied and a phase difference between the first transmission pulse signal and the first transmission pulse signal after the polarity of the pulse signal is inverted is less than ± 90 ° . A second output mode for applying a transmission pulse signal, and the capacitive touch sensor has a first operation mode for detecting the proximity of a human body to any of the plurality of detection units. In the first operation mode, the pulse output means divides the plurality of detection units into a first group and a second group, and transmits the transmission electrodes of the detection units belonging to the first group in the first output mode. First Applying a transmission pulse signal, applying the second transmission pulse signal in the second output mode to the transmission electrodes of the detectors belonging to the second group, and the integrating means outputs the amplified output and the inverted output, The integral output is calculated by alternately selecting and integrating in synchronization with the pulse signal and the inverted pulse signal, and the determination means has a value equal to or greater than a first threshold value on the positive side with respect to a reference value or a negative value. When it is less than or equal to the second threshold, it is determined that there is a human body approaching any of the plurality of detection units, and when the integrated output is smaller than the first threshold and greater than the second threshold, It is characterized in that it is determined that there is no human body proximity in any of the detection units.

  In the present invention configured as described above, the reception electrodes of a plurality of detection units are electrically connected, and if there is a human body close to any of the detection units, a change appears in the integrated output. In one operation mode, the proximity of the human body to any one of the detection units can be detected based on the value of the integrated output. Therefore, in this detection, since it is only necessary to cause the sensor circuit to perform detection processing only once in a predetermined detection period for all of the plurality of detection units, it is possible to save power during the standby period.

  In that case, in this invention, it groups into the detection part (1st group) which applies the said 1st transmission pulse with respect to several detection parts, and the detection part (2nd group) which applies the said 2nd transmission pulse. By doing so, the polarity of the voltage output appearing at the receiving electrode is reversed between the groups of the detection units. With this configuration, the voltage output can be canceled between groups, so that the integrated output output from the integrating means can be handled with the same dynamic range as the sensor circuit that processes only one detector. As a result, it is possible to simultaneously monitor voltage changes for a plurality of detection units while maintaining detection sensitivity.

  Specifically, by applying pulse signals of opposite polarities to each of the two groups, when there is no human body approaching to any of the detection units (when not in proximity), the receiving electrodes of each detection unit The amplified output and the inverted output of the induced voltage output are canceled, and the integrated output becomes zero (that is, the reference voltage). Therefore, even if reception signals from multiple detection units are detected simultaneously, the integrated output does not become a multiple of the number of detection units, and the dynamic range of the detection circuit can be used effectively, and the detection sensitivity can be increased. Can be maintained. In a stand-by state that is not in proximity, it is possible to simultaneously monitor the proximity of a human body to a plurality of detection units only by monitoring a difference from zero (reference voltage). It can be determined by zero balance, not by the magnitude determination of the integrated output.

  In addition, the capacitance detection operation has a very small change in capacitance to be detected. Therefore, a change in electrical operation (change in pulse frequency or circuit characteristics) caused by temperature, circuit voltage, etc., or electrostatic capacitance such as humidity. Although it is susceptible to various influences such as changes to the coupling, the present invention functions so as to cancel these influences. For example, if the change in the output pulse becomes dull (becomes sharp), the integrated output tends to decrease for the same coupling capacitance, but this affects the integration processes with opposite polarities, and as a result, It will not appear. As described above, the present invention has an effect of canceling the variation of the circuit and structure.

  In the first operation mode, such as when the number of electrodes is an odd number or when the sizes of the electrodes are different, the total of the capacitive coupling of the transmission electrode and the reception electrode of the detection unit belonging to the first group and the second group There may be a difference in the total electrostatic coupling between the transmission electrode and the reception electrode of the detection unit, and it is difficult to balance the integral output.

However, in the present invention, by adjusting the phase difference between the first transmission pulse and the second transmission pulse, it is possible to cancel a part of the induced voltage output from the reception electrode of the group having a large total of electrostatic coupling, and to integrate The output can be adjusted to zero or a reference voltage.

  The present invention also includes a pulse output means for outputting a pulse signal having a predetermined frequency, and a transmission electrode and a reception electrode that are arranged close to each other and are electrostatically coupled. The pulse signal and the phase of the transmission electrode are substantially the same. A detection unit configured to output an induced voltage output by the receiving electrode when the same first transmission pulse signal is applied, and outputs an amplified output by amplifying the induced voltage output received from the receiving electrode Amplifying means, inverting means for inverting the polarity of the amplified output received from the amplifying means and outputting an inverted output, and the amplified output and the inverted output are alternately selected in synchronization with the pulse signal and integrated. An electrostatic capacity type touch sensor comprising: an integrating unit that outputs an integrated output; and a determining unit that determines proximity of a human body to the detecting unit based on the integrated output received from the integrating unit. The plurality of reception electrodes constituting the plurality of detection units are electrically connected to each other, and the pulse output means is provided for each of the plurality of transmission electrodes constituting the plurality of detection units. A first output mode for applying the first transmission pulse signal, and a second output mode for applying a second transmission pulse signal in which the duty ratio of the pulse is changed after inverting the polarity of the pulse signal, The capacitive touch sensor includes a first operation mode for detecting that a human body has approached any of the plurality of detection units. In the first operation mode, the pulse output unit includes the plurality of pulse output units. The detection unit is divided into a first group and a second group, the first transmission pulse signal is applied to the transmission electrode of the detection unit belonging to the first group, and the transmission power of the detection unit belonging to the second group is applied. The second transmission pulse signal is applied to the integration unit, the integration unit alternately selects and integrates the amplified output and the inverted output in synchronization with the pulse signal to calculate an integration output, and the determination unit includes: When the integral output is greater than or equal to the first threshold value on the positive side or less than or equal to the second threshold value on the negative side with respect to a reference value, it is determined that any of the plurality of detection units has approached a human body, and the integral output However, when it is smaller than the first threshold value and larger than the second threshold value, it may be configured to determine that there is no human body approaching in any of the plurality of detection units.

  The present invention also includes a pulse output means for outputting a pulse signal having a predetermined frequency, and a transmission electrode and a reception electrode that are arranged close to each other and are electrostatically coupled. The pulse signal and the phase of the transmission electrode are substantially the same. A detection unit configured to output an induced voltage output by the receiving electrode when the same first transmission pulse signal is applied, and outputs an amplified output by amplifying the induced voltage output received from the receiving electrode Amplifying means, inverting means for inverting the polarity of the amplified output received from the amplifying means and outputting an inverted output, and the amplified output and the inverted output are alternately selected in synchronization with the pulse signal and integrated. An electrostatic capacity type touch sensor comprising: an integrating unit that outputs an integrated output; and a determining unit that determines proximity of a human body to the detecting unit based on the integrated output received from the integrating unit. The plurality of reception electrodes constituting the plurality of detection units are electrically connected to each other, and the pulse output means is provided for each of the plurality of transmission electrodes constituting the plurality of detection units. A first output mode for applying the first transmission pulse signal, and a second output mode for applying a second transmission pulse signal whose number of pulses is changed after inverting the polarity of the pulse signal, The capacitive touch sensor includes a first operation mode that detects that a human body is in proximity to any of the plurality of detection units. In the first operation mode, the pulse output unit includes the plurality of detection units. Are grouped into a first group and a second group, the first transmission pulse signal is applied to the transmission electrode of the detection unit belonging to the first group, and the second transmission pulse is applied to the transmission electrode of the detection unit belonging to the second group. Sending Applying a pulse signal, the integrating means alternately selects and integrates the amplified output and the inverted output in synchronization with the pulse signal to calculate an integrated output, and the determining means calculates the integrated output as follows: When the threshold value is greater than or equal to the first threshold value on the positive side or less than or equal to the second threshold value on the negative side with respect to a reference value, it is determined that any of the plurality of detection units has approached a human body, and the integrated output is the first output When it is smaller than the threshold value and larger than the second threshold value, it may be configured that it is determined that none of the plurality of detection units has a human body approaching.

  According to the present invention configured as described above, it is possible to monitor the proximity of a human body with high sensitivity while canceling out external influences and differences in electrostatic coupling of electrodes.

  Preferably, in the present invention, in the first operation mode, when the integrated output is equal to or higher than the first threshold value or equal to or lower than the second threshold value, the mode shifts to the second operation mode. Depending on whether the integrated output is greater than or equal to the first threshold value or less than the second threshold value, it is determined in which group the detection unit with human body proximity is included, and the pulse output means has human body proximity The detection units of the determination group determined to include the detection unit are further grouped into a first group and a second group in the second operation mode, and the detection electrodes belonging to the first group in the second operation mode are transferred to the first transmission electrode. A pulse signal is applied in the one output mode, an inverted pulse signal is applied in the second output mode to the transmission electrodes of the detectors belonging to the second group in the second operation mode. A fixed voltage is applied in a third output mode in which a fixed voltage is applied to the transmission electrodes of the non-determination group detection units that have not been determined to include a detection unit having proximity, and the integration unit calculates an integral output, The determination unit determines whether the detection unit with the proximity of the human body is included in the first group or the second group in the second operation mode based on the integrated output.

  In the present invention configured as described above, in the first operation mode, it is possible to simultaneously monitor all the detection units and determine whether or not a human body has approached any of the detection units. The detection unit that is close to the human body is not specified. For this reason, in the present invention, when it is determined in the first operation mode (standby mode) that there is a human body approaching one of the detection units, the second operation mode (sorting mode) is entered, and the human body Narrow down the detection unit (proximity detection unit) with proximity. For this reason, the group including the proximity detection unit is specified by the integrated output in the first operation mode, and further, this determination group is divided into groups, pulse signals having different polarities are respectively applied to obtain integrated outputs, and the integrated outputs are obtained. The group including the proximity detection unit can be identified from the characteristics (polarity, size) of. Then, by performing the second operation mode once or a plurality of times, it is possible to finally specify one proximity detection unit. As described above, in the present invention, even in the classification mode, the proximity detection unit is specified by grouping, so that the number of detection processes can be reduced. As a result, when the number of detection units is large, a greater power saving effect can be obtained as compared with a method in which individual detection units are subjected to detection processing.

Preferably, in the present invention, in the second operation mode, when the determination group is further grouped, if the total number of detection units belonging to the determination group is an even number, the detection unit is divided into two equal parts, and the second operation mode When the total number of detection units belonging to the determination group is an odd number, a fixed voltage is applied only to the transmission electrode of one detection unit, and the other detection units are divided into two equal parts. First and second groups in the second operation mode are formed.
In the present invention configured as described above, when the number of detection units included in the determination group is an even number, the first and second groups are formed by being divided into two equal parts. A fixed voltage is applied to, and the others are divided into two equal parts. As a result, if the integral output is greater than or equal to the threshold value in either positive or negative direction, the group including the proximity detector can be determined accordingly.If the integral output does not exceed the threshold value in either positive or negative direction, the fixed voltage It can be determined that one detection unit to which is applied is a proximity detection unit.

In the present invention, it is preferable to further include a third operation mode. In the third operation mode, the pulse output means applies a pulse signal to the transmission electrode of one of the plurality of detection units, and the other. A fixed voltage is applied to the transmission electrode of the detection unit, the integration unit calculates an integration output, and the determination unit determines whether there is a human body approaching the one detection unit based on the integration output.
In the present invention configured as described above, when one proximity detection unit is finally specified, the detection unit is applied to the detection unit by individually applying a pulse signal to the detection unit. It can be confirmed. Further, after the proximity of the human body, when the proximity of the human body is lost (for example, the finger is released), it can be confirmed that the detection unit is no longer the proximity detection unit, and the first operation mode (standby mode) is again performed. ).

Preferably, in the present invention, in the first operation mode, when the integrated output is equal to or higher than the first threshold value or equal to or lower than the second threshold value, the operation mode is shifted to the second operation mode. When a certain detection unit is specified as one, the mode shifts to the third operation mode.
In the present invention configured as described above, it is sufficient to perform detection processing once every predetermined detection period (for example, 8 Hz) while operating in the standby state in the first operation mode, thereby greatly increasing the standby power. Can be reduced. Furthermore, after shifting from the standby mode to the classification mode (second operation mode), grouping is performed and the group including the proximity detection unit is sequentially specified, so that the number of detection processes can be reduced. The proximity detector can be quickly identified. For this reason, even if it is a case where a user touches a detection part momentarily with a finger, proximity detection can be performed reliably. Furthermore, it can detect from the classification mode to the confirmation mode (third operation mode) that the human body is close to the proximity detector and that the human body is no longer close.

  According to the present invention, in a capacitive touch sensor having a plurality of electrodes, it is possible to significantly reduce power consumption during standby and during operation, and to suppress the occurrence of erroneous detection.

It is an external view of the electronic device (remote control) in 1st Embodiment of this invention. It is an electric block diagram of the electronic device in 1st Embodiment of this invention. It is explanatory drawing of the 1st operation mode in 1st Embodiment of this invention. It is explanatory drawing of the 1st operation mode in 1st Embodiment of this invention. It is explanatory drawing of the 2nd operation mode in 1st Embodiment of this invention. It is explanatory drawing of the 3rd operation mode in 1st Embodiment of this invention. It is explanatory drawing which shows the flow of detection operation | movement of the electrostatic capacitance type touch sensor in 1st Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 1st Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 1st Embodiment of this invention. It is an external view of the electronic device (remote control) in 2nd Embodiment of this invention. It is an electrical block diagram of the electronic device in 2nd Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 2nd Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 2nd Embodiment of this invention. It is an external view of the electronic device (remote control) in 3rd Embodiment of this invention. It is an electric block diagram of the electronic device in 1st Embodiment of this invention. It is explanatory drawing of the 1st operation mode in 1st Embodiment of this invention. It is explanatory drawing of the 1st operation mode in 1st Embodiment of this invention. It is explanatory drawing of the 1st operation mode in 1st Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 3rd Embodiment of this invention. It is an operation | movement flow of the electrostatic capacitance type touch sensor in 3rd Embodiment of this invention. It is an operation | movement flow regarding the pulse generation of the capacitive touch sensor in 3rd Embodiment of this invention. It is an operation | movement flow regarding the duty ratio change of the electrostatic capacitance type touch sensor in 3rd Embodiment of this invention. It is an operation | movement flow regarding the pulse number change of the electrostatic capacitance type touch sensor in 3rd Embodiment of this invention.

A capacitive touch sensor (hereinafter also referred to as “touch sensor”) according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 8. First, the configuration of the touch sensor will be described with reference to FIGS.
This embodiment is an example in which a touch sensor is applied to a remote controller for a warm water flush toilet seat. As shown in FIG. 1, the remote controller 1 has a plurality of switches 2 a-2 h and a liquid crystal display unit 3.

  The plurality of switches include “stop” (switch 2a), “wet washing” (switch 2b), “bidet washing” (switch 2c), “warm air drying” (switch 2d), “toilet bowl washing” (switch 2e ), “Toilet bowl small wash” (switch 2f), “Toilet seat open / close” (switch 2g), and “Toilet lid open / close” (switch 2h). Of these switches, the four switches 2a-2d are capacitive switches.

  FIG. 2 shows the configuration of the sensor circuit of the remote controller 1. The remote controller 1 of the present embodiment includes a control unit 10 having a CPU, an electrode 20 as an electrode corresponding to the four switches 2a-2d, and a detection circuit 30 that processes a detection signal from the electrode 20. .

  The control unit 10 has output ports P01, P02, P03, P04, P11, P12 and an input port P20. The output ports P01, P02, P03, and P04 are respectively connected to four switches, and the control unit 10 as a pulse output means has a pulse transmission signal (or a fixed voltage transmission signal) V1 composed of a plurality of pulse trains. , V2, V3, and V4 are output. Note that the pulse signal or the pulse transmission signal is a signal that includes a plurality of pulses and is repeatedly turned on / off (a Hi level / Lo level voltage) alternately. The output port P11 outputs a timing signal INT of a pulse signal composed of a plurality of rectangular pulse trains to the detection circuit 30. The output port P12 outputs a reset signal RST to the detection circuit 30. The input port P20 receives the analog integration output from the detection circuit 30. The controller 10 determines the proximity of the human body to the switch based on the digital integrated output obtained by A / D converting the integrated output.

  The electrode 20 includes four electrodes 21, 22, 23, and 24. The transmission electrode 21a and the reception electrode 21b, the transmission electrode 22a and the reception electrode 22b, the transmission electrode 23a and the reception electrode 23b, the transmission electrode 24a, and the reception, respectively. It has an electrode 24b. In each electrode, the transmission electrode and the reception electrode are arranged close to each other so as to be electrostatically coupled. The electrostatic coupling is determined by the area and distance between the transmitting electrode and the receiving electrode, and the dielectric constant of the substance existing between them.

  When a user's finger contacts or approaches any of the electrodes, the electrode or the vicinity thereof is substantially fixed to the GND potential (ground potential) via the human body. At this time, a GND potential electrode (actually a user's finger) is inserted between the transmission electrode and the reception electrode, and the electrostatic capacitance between the transmission electrode and the reception electrode is blocked by the GND potential electrode. . Therefore, the coupling capacity between the transmission electrode and the reception electrode is reduced. The proximity of the human body can be determined by the change in the coupling capacity.

  The transmission electrodes 21a, 22a, 23a, 24a, and 25a are respectively connected to the output ports P01, P02, P03, P04, and P05 via electric wiring. Further, the receiving electrodes 21b, 22b, 23b, 24b, and 25b are connected to the detection circuit 30 by electric wiring in a state where they are electrically connected to each other. When a pulse signal is transmitted from the output port of the control unit 10 to the transmission electrode, a potential change is induced in the corresponding reception electrode due to a potential change of the transmission electrode based on the pulse signal. This is expressed in FIG. 2 by electric lines of force (broken lines) from the transmission electrode to the reception electrode. Thereby, an induction voltage output is output from the receiving electrode by applying the transmission signal to the transmitting electrode.

  The detection circuit 30 includes amplification means, inversion means, and integration means. The output wiring from the electrode 20 is connected to the fixed potential GND through the capacitor 31 and is also connected to the amplifying means. Therefore, the transmission signal from the control unit 10 is applied to a series circuit of the capacitor and the capacitor 31 including the transmission electrode and the reception electrode.

  The amplifying unit includes resistors 32 and 34 and an OP amplifier 33. The resistor 32 is connected to the output wiring of the electrode 20 and to the inverting input of the OP amplifier 33. Therefore, the inverting input of the OP amplifier 33 is supplied with the potential at the connection portion of both capacitors in the series circuit of the capacitor and the capacitor 31 including the transmission electrode and the reception electrode. The capacitor 31 is a capacitance added for the purpose of (relatively) reducing the influence of the stray capacitance of the circuit connected from the receiving electrode to the amplifying means, and is not necessary in terms of the operation principle of touch detection. The resistor 34 is connected between the inverting input and the output of the OP amplifier 33. The non-inverting input of the OP amplifier 33 is connected to the reference voltage source 45. The reference voltage source 45 provides a reference voltage Vref (for example, 1.5 V) of the detection circuit 30 to the GND.

  The inverting means includes resistors 35 and 37 and an OP amplifier 36. The resistor 35 is connected between the output of the amplification means and the inverting input of the OP amplifier 36. The resistor 37 is connected between the inverting input and the output of the OP amplifier 36. The non-inverting input of the OP amplifier 36 is connected to the reference voltage source 45. The resistors 35 and 37 have the same resistance value, and the signal amplitude is equal and the polarity is inverted at the input and output of the inverting means.

  The integrating means includes a resistor 38, an OP amplifier 39, and a capacitor 40. The outputs of the amplifying means and the inverting means are selectively input to the inverting input of the OP amplifier 39 via the resistor 38. The capacitor 40 is connected between the inverting input and the output of the OP amplifier 39. The non-inverting input of the OP amplifier 39 is connected to the reference voltage source 45. The integrating means outputs an integrated output based on the potential difference from the reference voltage Vref formed in the capacitor 40 by integration processing to the input port P20 of the control unit 10.

  An analog switch 41 as a reset means is connected between both ends of the capacitor 40. The analog switch 41 is normally off and is configured to be turned on by a reset signal RST from the control unit 10. When the analog switch 41 is turned on for a predetermined period by the reset signal RST, the voltage across the capacitor 40 is reset to zero.

  Further, the integration means includes analog switches 42 and 43 and an inverter circuit (inversion circuit) 44 as selection means. At the input / output of the inverter circuit 44, the polarity of the signal is inverted. The analog switch 42 is disposed between the output of the amplifying unit and the resistor 38 of the integrating unit, and is configured to be turned on / off by a timing signal INT from the control unit 10. On the other hand, the analog switch 43 is disposed between the output of the inverting means and the resistor 38 of the integrating means, and is configured to be turned on / off by the timing signal INT inverted by the inverter circuit 44. Therefore, during the output of the timing signal INT, the analog switches 42 and 43 are turned off when one is turned on and turned off when the other is turned off, and are turned on and off alternately in time.

The timing signal INT is a rectangular wave pulse signal having a predetermined frequency at which the Hi / Lo potential level is switched. The analog switches 42 and 43 are turned on when the Hi level potential of the timing signal INT or the inverted timing signal INT is input, and are turned off during other periods.
In the present embodiment, the timing signal INT is a pulse signal having a duty ratio of 50%, and the pulse widths of the Hi level and the Lo level are the same, but the duty ratio is not necessarily 50%.

Next, the operation of the touch sensor of this embodiment will be described with reference to FIGS.
The touch sensor of the present embodiment is configured to operate in the first operation mode (standby mode), the second operation mode (sorting mode or narrowing mode), and the third operation mode (confirmation mode).

The first operation mode is a mode for waiting for the touch sensor to be operated. First, referring to FIG. 3, a standby state in which the user is not approaching or touching the electrode 20 will be described.
In the first operation mode, as shown in FIG. 3, the control unit 10 outputs the reset signal RST from the output port P12 at the time T0 when the detection processing operation starts, turns on the analog switch 41, and sets the potential difference of the capacitor 41. Reset to zero. As a result, the output (integrated value) of the integrating means becomes the reference voltage Vref of the reference voltage source 45.

  Next, the control part 10 as a pulse output means outputs the timing signal INT from the output port P11. Thus, the analog switch 42 is turned on when the pulse signal of the timing signal INT is at the Hi level. On the other hand, when the inversion timing signal INT whose polarity is inverted by the inverter circuit 44 is at the Hi level (that is, when the timing signal INT is at the Lo level), the analog switch 43 is turned on.

  The controller 10 outputs pulse signals V1, V2, V3, and V4 from the output ports P01, P02, P03, and P04 in synchronization with the timing signal INT. At that time, the control unit 10 groups the plurality of output ports (or electrodes 20) into two groups. In the present embodiment, the total number of the electrodes 20 is four and is an even number, so that each group is divided into equal numbers. That is, grouping is performed so that the total of the electrostatic coupling of each electrode is substantially equal between the groups. In this example, the first group is output ports P01 and P02 (electrodes 21 and 22), and the second group is output ports P03 and P04 (electrodes 23 and 24).

  The control unit 10 has three output modes as modes for outputting a signal from the output port. In the first output mode, rectangular pulse signals having the same frequency and the same polarity synchronized with the timing signal INT are output. In the second output mode, a rectangular wave pulse signal having the same frequency synchronized with the timing signal INT but having a reverse polarity is output. That is, in the first output mode and the second output mode, pulse signals having opposite polarities are output. In the third output mode, a fixed voltage signal is output. Specifically, the pulse signal is, for example, a pulse output in which a Hi potential level (usually a circuit power supply voltage, for example, 3 V) and a Lo potential level (usually 0 V of the ground potential) are switched four times. The voltage can be the same as the Lo potential level (eg, 0 V). Alternatively, the fixed voltage may be set to the Hi potential level. Note that the number of switching of the pulse signal may not be four as long as it is one or more, but is preferably a plurality of times from the viewpoint of noise removal as long as the power consumption is not excessively increased.

In the present embodiment, as shown in FIG. 3, the first group is operated in the first output mode, and the second group is operated in the second output mode.
The electrodes 21, 22, 23, and 24 receive the pulse signals V1, V2, V3, and V4 from the output ports of the control unit 10 by the transmission electrodes 21a, 22a, 23a, and 24a, and thereby the corresponding reception electrodes 21b and 22b. , 23b, 24b, potential changes are induced.

  In the period T1-T2, a pulse having a high potential level is input to the transmission electrode in the electrodes 21 and 22, and thereby a positive voltage is induced in the reception electrode. However, in the electrodes 23 and 24, Lo is applied to the transmission electrode. Since a potential level pulse is input, a voltage corresponding to the Lo potential level is induced in the receiving electrode. However, since the four receiving electrodes are electrically connected, they have the same potential, and a receiving signal (receiving electrode voltage) having a certain potential is output from the electrode 20 to the detection circuit 30.

  Then, in the next period T2-T3, similarly to the period T1-T2, a pulse at the Lo potential level is input to the electrodes 21 and 22, and a pulse at the Hi potential level is input to the electrodes 23 and 24. A reception signal having the same size as the period T1-T2 is output. Thus, in a state where the user does not operate the switch (electrode 20) (a state where the finger or the like is not approached or touched), the input of the timing signal INT in the Hi level period and the Lo level period is balanced, and thus the period T1 to T9. A reception signal having a constant amplitude is output.

  The amplification means of the detection circuit 30 amplifies the received signal with reference to the reference voltage Vref. At this time, since there is no user operation, the output of the amplification means is zero (the signal is zero, but the output potential is the reference voltage Vref). Actually, since the noise component and the like are included, the output of the amplification means has a slight value. The inverting means inverts the output of the amplifying means with an equal amplitude with respect to the reference voltage Vref.

The integrating means of the detection circuit 30 selectively receives the outputs of the amplifying means and the inverting means alternately. Specifically, the output of the amplification means is input when the timing signal INT is at the Hi level, and the output of the inversion means is input when the timing signal INT is at the Lo level. For example, in the period T1-T2, the output of the amplifying unit is integrated by the integrating unit, and in the subsequent period T2-T3, the output of the inverting unit is integrated by the integrating unit. Then, the integration operation in the period T1-T3 is repeated four times in total in the period T1-T9. In FIG. 3, an integration output Vint is obtained by this integration operation.
The integration output Vint will be described assuming that it takes a positive or negative value with the reference voltage Vref as a reference value. That is, since the integration output Vint is a potential based on 0 V in terms of circuit, an offset corresponding to the reference voltage Vref is added, and it is inappropriate for handling as an output signal of the integration means. That is, the difference [Vint−Vref] between Vint and the reference voltage Vref should be treated as an integral output in the sense of a signal, but the explanation will be complicated, and this will be explained as Vint.

  The integration operation in the period T1-T3 has not only a signal accumulation function of signal integration but also a noise removal effect. In other words, if the frequency of the signal that causes noise does not coincide with the frequency that takes the period T1-T3 as one cycle, the integration amount is canceled in the periods T1-T2 and T2-T3, and noise is reduced. Therefore, it can be said that only the operation in the period T1-T3 is one noise removal integration operation. Thereby, the S / N ratio of the integrated output can be improved.

  In this embodiment, the number of integrations is set to 4. However, as the number of integrations increases, the signal amount and noise removal performance improve, and setting the number of integrations more for detection sensitivity and S / N ratio. Since it is advantageous, there is no limit to the number of integrations.

In the standby state, the integration means output is A / D converted immediately after the end of the pulse signal transmission period (T1-T9). Since the power consumption cannot be reduced if the detection circuit 30 is always energized, the power supply of the detection circuit 30 is turned on at the timing T0 in FIG. 3, and the power supply is turned on at the timing T10 when the A / D conversion is completed. Configure to turn off. Although not shown in FIG. 3, the operational amplifiers 33, 36, and 39 of the detection circuit 30 may be provided with a power switch that can be operated from the control unit 10. The control unit 10 as a determination unit compares the A / D-converted integrated output (integrated value) Vint with a threshold value and determines whether or not there is a proximity of a user's finger or the like to any of the electrodes 21-24. To do. In the present embodiment, a positive first threshold value Vth1 and a negative second threshold value Vth2 with respect to the reference voltage Vref are set as threshold values, and these absolute values are the same value Vth (Vth1 = Vth, Vth2 = -Vth).
Note that the absolute values of the first threshold value and the second threshold value may be different.

In the case of FIG. 3, since the integrated output Vint has not reached either the first threshold value Vth1 or the second threshold value Vth2 (−Vth <Vint <Vth), the control unit 10 applies to any electrode 21-24. It is also determined that there is no proximity of the user's finger or the like. In the case of this non-proximity determination, the control unit 10 repeats the first operation mode (standby mode) every predetermined detection cycle.
Therefore, in the standby mode of the present embodiment, only one detection processing operation is performed per detection cycle, and compared with a case where detection processing operations are individually performed for all electrodes, standby consumption is performed. Electric power can be greatly reduced.

Next, a case where the user operates the electrode 20 in the first operation mode will be described with reference to FIG.
When a user's finger or the like approaches any electrode (in this example, the user touches the electrode 23), an induced voltage that should be induced in the receiving electrode 23b by the pulse signal V3 input to the transmitting electrode 23a is almost zero. No longer induced. Therefore, the transmission signal V3 is not substantially input to the electrode 23, the transmission signals V1 and V2 of the first output mode are input to the electrodes 21 and 22, and the transmission signal V4 of the second output mode is input to the electrode 24. Will be equal to the situation.

  For this reason, the received signal varies in the opposite polarity to the input signal V2 to the electrode 23 (that is, the same polarity as the timing signal INT). Therefore, the amplifying means for inverting and amplifying the received signal outputs an amplified signal that varies with the opposite polarity to the timing signal INT, and the inverting means for inverting this with the same amplitude is the inverted signal that varies with the same polarity as the timing signal INT. Is output.

  The integrating means alternately selects and integrates the amplified signal and the inverted signal in synchronization with the switching of the pulse of the timing signal INT, and outputs the integrated output Vint to the input port P20. As shown in FIG. 4, the input signal to the integrating means has a negative value with respect to the reference voltage Vref. Since the integrating means inverts and integrates the integrated output Vint, the integration output Vint is obtained by performing a plurality of integrations. It becomes a positive value with respect to the voltage Vref.

  Based on the magnitude (amplitude) and polarity of the integrated output Vint, the control unit 10 determines whether the user's finger or the like has approached or touched the electrode of the first group or the second group. That is, since the integrated output Vint is equal to or greater than the first threshold value Vth1 (Vint ≧ Vth), the control unit 10 determines that the user's finger or the like has approached any electrode because the threshold value is exceeded.

Furthermore, since the integrated output Vint is a positive value, the control unit 10 determines that the user's finger or the like has approached the second group, which is an electrode to which a pulse signal having a polarity opposite to that of the timing signal INT is input. To do.
When the user's finger or the like is close to the first group of electrodes to which a pulse signal having the same polarity as the timing signal INT is input, the integrated output Vint has a negative value with respect to the reference voltage Vref.
In the first operation mode, when the control unit 10 determines the proximity of the user's finger or the like to any one of the electrodes, the first operation mode is terminated and the process proceeds to the second operation mode.

Next, the second operation mode will be described with reference to FIG.
When the mode is shifted to the second operation mode, the control unit 10 further groups the electrodes of the group (in this example, the second group) determined to be close to the user's finger or the like into the first group and the second group. When the total number of the target electrodes is an even number, the grouping is divided into two equal parts, and if it is an odd number, the other electrodes except for one arbitrarily selected electrode are divided into two equal parts. Will be described in the form). In this example, since the total number of target electrodes is an even number (two), the first group is only the electrodes 23 and the second group is only the electrodes 24.

After outputting the reset signal RST, the control unit 10 operates the first group set in the second operation mode in the first output mode, and operates the second group in the second output mode. In addition, in the first operation mode, the electrodes of the group that are not determined to include the electrodes that are close to the user's finger or the like (electrodes 21 and 22 in this example) are fixed in the third output mode in the second operation mode. A voltage signal is applied.
Note that the fixed voltage signals to the electrodes 21 and 22 do not substantially affect the integrated output.

  In the example of FIG. 5, the pulse signal V3 having the same polarity as the timing signal INT is input to the electrode 23 in which the user's finger or the like is in close proximity. It can be considered that the signal V3 is not substantially input. Therefore, in the example of FIG. 5, it can be considered that substantially no signal is input to the electrodes 21, 22 and 23, and the inverted pulse signal V 4 is input only to the electrode 24.

  Therefore, mainly due to the input of the inverted pulse signal V4 to the electrode 24, the integrated output Vint becomes a negative value, and this integrated output Vint reaches the second threshold value Vth2 (Vint ≦ −Vth). Accordingly, the control unit 10 includes an electrode in which a user's finger or the like is close to a group (in this example, the first group) in which a pulse signal having the same polarity as the timing signal INT is input based on the magnitude and polarity of the integrated output Vint. Judge that

  That is, since the magnitude of the integral output Vint has reached the second threshold value Vth2, it is determined that there is a finger or the like in any group, and the integral output Vint is in a negative direction with respect to the reference voltage Vref. Since the threshold value is reached, the group to which the pulse signal having the same polarity as the timing signal INT is input is specified. Therefore, in the example of FIG. 5, the first group (that is, the electrode 23) is specified as an electrode having a proximity such as a finger.

In the second operation mode, since the control unit 10 can identify one electrode such as the user's finger that is close, the second operation mode ends and the third operation mode is entered.
In this example, one execution of the second operation mode identifies one electrode that is close to the finger or the like, but the group identified in the second operation mode includes a plurality of electrodes. In this case, the second operation mode is repeatedly executed, so that processing for narrowing down to only one electrode can be performed.

Next, the third operation mode will be described with reference to FIG.
When shifting to the third operation mode, the control unit 10 inputs the pulse signal V3 only to the electrode (in this example, the electrode 23) for which the proximity of the user's finger or the like has been determined, and fixes it to the other electrodes that have not been specified. Input voltage signal.

After outputting the reset signal RST, the controller 10 operates the electrode 23 in the first output mode, and operates the other electrodes 21, 22, and 24 in the third output mode.
In the example of FIG. 6, the pulse signal V3 having the same polarity as the timing signal INT is input to the electrode 23 that is close to the user's finger, but the pulse signal is applied to the electrode 23 due to the proximity of the user's finger or the like. It can be considered that is not substantially input. For this reason, in the example of FIG. 6, it can be considered that substantially no signal is input to all the electrodes 21-24.

  Therefore, the integral output Vint does not reach either the first threshold value Vth1 or the second threshold value Vth2 (−Vth <Vint <Vth). Thereby, the control part 10 confirms that a user's finger | toe etc. are still near the electrode 23 which is inputting the pulse signal.

On the other hand, when the user finishes the operation on the electrode 23 and removes his / her finger from the electrode 23, the received voltage varies as shown in FIG. 4 due to the input of the pulse signal V3 to the electrode 23. It becomes. Thereby, the integral output Vint becomes a value equal to or greater than the first threshold value Vth1.
When determining that the integrated output Vint has reached the first threshold value or the second threshold value in the third operation mode, the control unit 10 determines that the user's finger or the like has moved away from the electrode. By this determination, the third operation mode ends and the operation returns to the first operation mode (standby mode) again.

FIG. 7 shows the overall flow of the example shown in FIGS.
In FIG. 7, the detection cycle of the first operation mode is indicated by a period T100. In this embodiment, the detection frequency is 8 Hz (detection cycle is 125 msec). For this reason, when the proximity of the user's finger or the like is not detected in the first operation mode, only one detection operation is performed per detection cycle. This is one time regardless of the total number of electrodes included in the electrode 20. In the present embodiment, the detection processing time (T0-T10) required for one detection operation is, for example, about 2 msec.
Therefore, in the standby state where there is no user operation, the frequency of the detection operation can be reduced. As a result, it is not necessary to perform the detection operation for most of the time, so that standby power consumption can be greatly reduced.

When there is a user operation in a detection cycle (T101-T103) of 125 msec following the detection cycle T100 in the first operation mode, the integrated output Vint reaches the first threshold value Vth1 or the second threshold value Vth2 in the period T101 (2 msec). Depending on whether the integrated output Vint reaches the first threshold value Vth1 or the second threshold value Vth2, the group including the electrode operated by the user is specified. Further, in order to quickly identify the electrode operated by the user, the period T102 (2 msec) of the second operation mode is started in the remaining period of the detection cycle, following the end of the period T101.
According to the total number of electrodes, the second operation mode is executed a plurality of times. In this example, the second operation mode is executed only once, so that the electrodes close to the user's finger or the like are specified. After the end of T102, the third operation mode period T103 is started in the remaining period of the detection cycle.
The period T102 and the period T103 end before the detection period (125 msec) has elapsed since the start of the period T101.

  In this way, in the second operation mode, which is the separation mode, the electrodes are grouped and the electrodes to be detected are narrowed down, so that the detection operation is performed on individual electrodes as in the past. The number of detection operations can be reduced as compared with the case where the steps are sequentially performed. Therefore, in this embodiment, power consumption can be reduced even in the sorting mode.

In a new detection period following the detection period (125 msec, in which the detection operation is performed for a total of 6 ms) in the period T101 to T103, the third operation mode is repeatedly executed until the user operation is completed. In this example, the third operation mode is repeated in the detection period T104 (125 msec) and the detection period T105 (125 msec).
In the detection period T105 of the third operation mode, when the user's finger or the like is separated from the electrode, the third operation mode is ended by the end of the detection period, and the first operation mode is repeated again in the next detection period.

  As described above, in the third operation mode which is the confirmation mode, the detection operation is performed only on the specified electrode, so that only one detection operation is performed per detection cycle in the third operation mode. Therefore, in this embodiment, power consumption can be reduced even in the confirmation mode.

Next, an operation flow of detection processing of the touch sensor according to the present embodiment will be described with reference to FIGS. 8A and 8B.
This operation flow is executed every 8 Hz. Therefore, the control unit 10 waits for the end of the previous detection cycle (125 msec) (step S1).
Next, in order to execute the first operation mode, the control unit 10 performs pulse signals having the same polarity as the timing signal INT based on the grouping (this is described as “positive pulse” in the operation flow) V1, V2. Are output from the output ports P01 and P02 (first group), and pulse signals of opposite polarity (this is described as “negative pulse” in the operation flow) V3 and V4 are output from the output ports P03 and P04 (second group). Output (step S2).

With the output of the pulse signal, the detection circuit 30 executes amplification processing, inversion processing, and integration processing, and outputs the integration output Vint to the input port P20 of the control unit 10 (step S3).
Upon receiving the integral output Vint, the control unit 10 compares the integral output Vint with a threshold value (step S4).
When the integrated output Vint has not reached either the first threshold value Vth1 or the second threshold value Vth2 (step S4; −Vth <Vint <Vth), the control unit 10 determines that none of the electrodes has been operated by the user. And this detection process is complete | finished (step S5).

On the other hand, when the integrated output Vint is equal to or lower than the second threshold value Vth2 (step S4; Vint ≦ −Vth), the control unit 10 shifts to the second operation mode. In this case, since the integral output Vint is swung to the negative side, the control unit 10 determines that the human body is close to the first group of the positive side electrodes (the same polarity as the timing signal INT). This group is further divided into groups, a pulse signal V1 having the same polarity as the timing signal INT is output from the output port P01 of the first group to the electrode 21, and a pulse having a reverse polarity is output from the output port P02 of the second group to the electrode 22. The signal V2 is output, and a fixed potential signal (GND = 0V) is output from the other output ports P03 and P04 (step S6).
Next, an integration process or the like is executed as in step S3 (step S7), and the process proceeds to step S8.

On the other hand, when the integral output Vint is equal to or higher than the first threshold value Vth1 (step S4; Vint ≧ Vth), the control unit 10 shifts to the second operation mode. In this case, since the integral output Vint is swinging to the positive side, the control unit 10 determines that the human body is close to the second group of the negative side (opposite polarity with respect to the timing signal INT). This group is further divided into groups, a pulse signal V3 having the same polarity as the timing signal INT is output from the first group output port P03 to the electrode 23, and a reverse polarity pulse is output from the second group output port P04 to the electrode 24. The signal V4 is output, and a fixed potential signal is output from the other output ports P01 and P02 (step S16).
Next, an integration process or the like is executed as in step S3 (step S17), and the process proceeds to step S18.

When returning to step S8 again, the control unit 10 performs a process of comparing the integral output Vint.
When the integrated output Vint has not reached either the first threshold value Vth1 or the second threshold value Vth2 (step S8; -Vth <Vint <Vth), the control unit 10 determines that the plurality of electrodes are touched by the user at the same time. The processing is terminated (step S5).
This process is an operation specification in which an electronic device (for example, a remote controller) to which the touch sensor of this embodiment is applied invalidates the simultaneous touch operation of a plurality of switches. If so, the determination process may be performed accordingly.

When the integral output Vint is equal to or lower than the second threshold value Vth2 (step S8; Vint ≦ −Vth), the control unit 10 shifts to the third operation mode. In this case, since the integral output Vint is swung to the negative side, the control unit 10 determines that the human body is close to the first group of the positive side electrodes (the same polarity as the timing signal INT). Since only the electrode 21 is included in the first group, it is determined that the user intends to operate the electrode 21 (step S9).
In the confirmation mode, the control unit 10 outputs a pulse signal V1 having the same polarity as the timing signal INT to the identified electrode 21, and outputs a fixed voltage signal to the other electrodes 22-24 (step S10). .

On the other hand, when the integral output Vint is greater than or equal to the first threshold value Vth1 (step S8; Vint ≧ Vth), the control unit 10 shifts to the third operation mode. In this case, since the integral output Vint is swinging to the positive side, the control unit 10 determines that the human body is close to the second group of the negative side (opposite polarity with respect to the timing signal INT). Since only the electrode 22 is included in the second group, it is determined that the user intends to operate the electrode 22 (step S11).
In the confirmation mode, the control unit 10 outputs a pulse signal V2 having the same polarity as the timing signal INT to the identified electrode 22, and outputs a signal of a fixed voltage to the other electrodes 21, 23, 24 (step). S12).

When returning to step S18 again, the control unit 10 performs a process of comparing the integral output Vint.
When the integrated output Vint does not reach either the first threshold value Vth1 or the second threshold value Vth2 (step S18; −Vth <Vint <Vth), the control unit 10 determines that the plurality of electrodes are touched by the user at the same time. The processing is terminated (step S5).

When the integral output Vint is equal to or lower than the second threshold value Vth2 (step S18; Vint ≦ −Vth), the control unit 10 shifts to the third operation mode. In this case, since the integral output Vint is swung to the negative side, the control unit 10 determines that the human body is close to the first group of the positive side electrodes (the same polarity as the timing signal INT). Since only the electrode 23 is included in the first group, it is determined that the user intends to operate the electrode 23 (step S19).
In the confirmation mode, the control unit 10 outputs a pulse signal V3 having the same polarity as the timing signal INT to the specified electrode 23, and outputs a signal of a fixed voltage to the other electrodes 21, 22, and 24 (Step S1). S20).

On the other hand, when the integral output Vint is greater than or equal to the first threshold value Vth1 (step S18; Vint ≧ Vth), the control unit 10 shifts to the third operation mode. In this case, since the integral output Vint is swinging to the positive side, the control unit 10 determines that the human body is close to the second group of the negative side (opposite polarity with respect to the timing signal INT). Since only the electrode 24 is included in the second group, it is determined that the user intends to operate the electrode 24 (step S21).
In the confirmation mode, the control unit 10 outputs the pulse signal V4 having the same polarity as the timing signal INT to the specified electrode 24, and outputs a fixed voltage signal to the other electrodes 21-23 (step S22). .

Returning to the original state, when the pulse signal in the confirmation mode is output in steps S10, S12, S20, and S22, the control unit 10 similarly performs integration processing and the like (step S13), and performs comparison processing of the integration output Vint. Perform (step S14).
When the integrated output Vint has not reached the first threshold value Vth1 (step S14; Vint <Vth), the control unit 10 determines that the user's finger or the like is still in proximity or touching the specified electrode. Then, it waits for the end of the current detection period (step S15).

When the current detection period ends, the process returns to step S13 again, executes an integration process, etc., and repeats step S14. When step S13 is executed, a pulse signal is output to the specified electrode, and a fixed voltage signal is output to the other electrodes.
On the other hand, when the integral output Vint is equal to or greater than the first threshold value Vth1 (step S14; Vint ≧ Vth), the control unit 10 determines that the user's finger or the like has moved away from the identified electrode, ends the processing, and ends step S1. Return to the first operation mode.

Next, a touch sensor according to a second embodiment of the present invention will be described with reference to FIGS. Note that in the second embodiment, differences from the first embodiment will be mainly described for easy understanding. The second embodiment is a case where the number of capacitive switches is six.
The difference between the remote controller 101 of the present embodiment and the remote controller 1 of the first embodiment is that the remote controller 101 further includes capacitance type switches 2i (“wet soft”) and 2j (“wide bidet”).

  As shown in FIG. 10, the electrode 20 further includes electrodes 25 and 26 corresponding to the switches 2i and 2j, and pulse signals are output from the output ports P05 and P06 of the control unit 10 to the respective transmission electrodes 25a and 26a. V5 and V6 are configured to be transmitted. In addition, the receiving electrodes 25b and 26b of the electrodes 25 and 26 are electrically connected to these similarly to the other receiving electrodes.

The operation flow of the touch sensor according to the second embodiment will be described with reference to FIG.
Steps S101-S105 are the same as steps S1-S5 of the first embodiment. However, in step S102, the control unit 10 outputs the pulse signals V1-V3 in the first output mode with the electrodes 21-23 as the first group, and outputs the pulse signals in the second output mode with the electrodes 24-25 as the second group. V4-V6 is output.

  In step S104, when the integral output Vint is equal to or less than the second threshold value Vth2 (step S104; Vint ≦ −Vth), the control unit 10 shifts from the first operation mode to the second operation mode, and in the first operation mode. It is determined that the user's finger or the like has approached any one of the electrodes of the first group, and further grouping is executed for this determination group. In this case, the number of electrodes included in the determination group is an odd number (three). Therefore, it cannot be divided into two equal parts. Therefore, the control unit 10 first divides the remaining electrodes excluding the electrodes 22 into two groups. That is, the electrode 21 is set to the first group, and the electrode 23 is set to the second group. Further, the excluded electrode 22 is set to the third group.

Then, the control unit 10 outputs a pulse signal in the first output mode to the first group, outputs a pulse signal in the second output mode to the second group, and the third group (excluded electrode 22). On the other hand, a fixed voltage signal is output in the third output mode (step S106).
Next, an integration process or the like (step S107) is executed in the same manner as in step S7, and an integration output Vint comparison process (step S108) is executed.

  In the comparison process, when the integrated output Vint is equal to or lower than the second threshold value Vth2 (Vint ≦ −Vth), the control unit 10 outputs the pulse signal in the first output mode to the first group in the second operation mode. It is determined that an electrode close to a finger or the like is included. Since only the electrode 21 is included in the first group, the control unit 10 determines that the user is operating the electrode 21 (step S109). Next, the control unit 10 shifts to the third operation mode, outputs a pulse signal V1 in the first output mode to the identified electrode 21, and outputs a fixed voltage signal to the other electrodes.

  In the comparison process, when the integrated output Vint does not reach either the first threshold value Vth1 or the second threshold value Vth2 (−Vth <Vint <Vth), the control unit 10 outputs a signal in the third output mode. It is determined that the third group in the second operation mode includes an electrode in which the user's finger or the like is close. That is, since the third group outputs in the third output mode, the integrated output is hardly affected regardless of the proximity of the human body. Since only the electrode 22 is included in the third group, the control unit 10 determines that the user is operating the electrode 22 (step S111). Next, the control unit 10 shifts to the third operation mode, outputs a pulse signal V2 in the first output mode to the identified electrode 22, and outputs a fixed voltage signal to the other electrodes.

  In addition, in the comparison process, when the integrated output Vint is equal to or higher than the first threshold value Vth1 (Vint ≧ Vth), the control unit 10 outputs the pulse signal in the second output mode to the second group in the second operation mode. It is determined that an electrode close to the finger or the like is included. Since only the electrode 23 is included in the second group, the control unit 10 determines that the user is operating the electrode 23 (step S113). Next, the control unit 10 shifts to the third operation mode, outputs the pulse signal V3 in the first output mode to the identified electrode 23, and outputs a fixed voltage signal to the other electrodes.

On the other hand, in the comparison process of step S104, when the integral output Vint is equal to or greater than the first threshold value Vth1 (step S104; Vint ≧ Vth), the control unit 10 transitions from the first operation mode to the second operation mode, It is determined that the user's finger or the like has approached any one of the electrodes in the second group in the operation mode, and grouping is further performed on this determination group as in step S106. Also in this case, since the number of electrodes included in the determination group is an odd number (three), the control unit 10 sets the electrodes 24, 25, and 26 to the first, third, and second groups, respectively.
Next, integration processing or the like (step S119) is executed in the same manner as in step S107, and integration output Vint comparison processing (step S120) is executed.

  In the comparison process, when the integral output Vint is equal to or less than the second threshold Vth2 (Vint ≦ −Vth), when the integral output Vint is equal to or greater than the first threshold Vth1 (Vint ≧ Vth), the integral output Vint is equal to or greater than the first threshold Vth1. (Step S104; Vint ≧ Vth), the control unit 10 determines that the first, third, and second groups include electrodes that are close to the user's finger or the like. As a result, in steps S121, S123, and S125, the electrodes 24, 25, and 26 are specified as electrodes that are close to the human body. Furthermore, in steps S122, S124, and S126, a pulse signal is output in the first output mode for each identified electrode, and a fixed voltage signal is output for the other electrodes.

  In Steps S110, S112, S114, S122, S124, and S126, when a pulse signal in the confirmation mode that is the third operation mode is output, Steps S115 to S117 are executed as in Steps S13 to S15 of the first embodiment. .

  As described above, in the second embodiment, when the number of electrodes included in the specified group is an odd number as a result of the execution of the first operation mode, further narrowing down is performed. Therefore, even if the total number of electrodes is an arbitrary number of 2 or more, it can be narrowed down to only one electrode by combining the second operation mode in the first embodiment and the second embodiment. That is, depending on whether the number of narrowed-down electrodes is even or odd, the second operation mode of the first embodiment is executed when the number is even, and the second operation mode of the second embodiment is executed when the number is narrow. You may comprise as follows.

Next, a touch sensor according to a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, differences from the second embodiment will be mainly described for easy understanding. The third embodiment is a case where the number of capacitive switches is five.
The difference between the remote controller 201 of the present embodiment and the remote controller 101 of the second embodiment is that the remote controller 201 does not include the capacitive switch 2j (“wide bidet”).

  As shown in FIG. 13, the electrode 20 includes an electrode 25 corresponding to the switch 2i, and is configured to transmit a pulse signal V5 from the output port P05 of the control unit 10 to the transmission electrode 25a. . Further, the receiving electrode 25b of the electrode 25 is electrically connected to these similarly to the other receiving electrodes.

  In the first operation mode, since the number of electrodes is an odd number, it cannot be divided equally. If a fixed potential is output as in step S106 of the second embodiment, the approach of the human body cannot be detected. Therefore, as shown in FIG. 14, output ports P01 and P02 (electrodes 21 and 22) are used as a first group, and first transmission pulse signals V1 and V2 having substantially the same phase as timing signal INT are output, and output port P03- 05 (electrodes 23-25) is set as the second group, and the second transmission pulse signal V3-V5 obtained by adding the phase difference ΔT to the inverted pulse signal obtained by inverting the polarity of the timing signal is configured to be output.

  By adding the phase difference, the integrated amount of the output that is not synchronized with the timing signal INT from the control unit 10 among the induced voltage outputs by the pulse signal (V3-V5) of the group having many electrodes can be intentionally canceled. it can. Thus, by adjusting the induced voltage output of the group having many electrodes, the integrated output value can be adjusted to the vicinity of the reference voltage even when the number of electrodes is odd.

Alternatively, in the first operation mode, when the number of electrodes is an odd number, a phase difference is not added to the pulse signal of the group having a large number of electrodes, but as shown in FIG. The duty ratio of V3-V5) may be varied.
By changing the duty ratio, the induced voltage output by the pulse signal (V3-V5) of the group with many electrodes becomes smaller than the induced voltage output by the pulse signal (V1, V2) of the group with few electrodes. The output value can be adjusted near the reference voltage.

Alternatively, in the first operation mode, when the number of electrodes is an odd number, a phase difference is added to the pulse signals of the group having a large number of electrodes, the duty ratio is changed, and as shown in FIG. The number of integrations may be different from the number of integrations of four groups with a small number of groups (V1, V2) and the number of integrations of three groups (V3-V5) with a large number of electrodes. In this embodiment, the number of integrations is reduced for all the pulse signals of the group having a large number of electrodes. For example, the pulse signals V3 and V4 are integrated four times, and the pulse signal V5 is integrated three times. It may be different for each pulse signal.
Since the sum of the induced voltage outputs by the pulse signals (V3 to V5) of the group having many electrodes is smaller than the sum of the induced voltage outputs by the pulse signals (V1, V2) of the group having few electrodes, the integrated output value is the reference. It can be adjusted around the voltage.

The operation flow of the touch sensor according to the third embodiment will be described with reference to FIGS.
In step S202, since the total number of electrodes 20 is an odd number, it cannot be divided into two equal parts. Therefore, the control unit 10 outputs the first transmission pulse signals V1 and V2 with the electrodes 21 and 22 as the first group, and outputs the second transmission pulse signals V3 and V5 with the electrodes 23-25 as the second group.

  Details of step S202 will be described with reference to FIGS. 18 to 20 show a flow for adding a phase difference between the first transmission pulse signal and the second transmission pulse signal, a flow for changing the duty ratio in the first transmission pulse signal and the second transmission pulse signal, and the first transmission, respectively. This is a flow for changing the number of pulses in the pulse signal and the second transmission pulse signal.

  When adding the phase difference between the first transmission pulse and the second transmission pulse, as shown in FIG. 18, in steps S301, the electrodes 21 and 22 are set as electrodes (first group) that output the first transmission pulse signal. Then, the electrodes 23-25 are set to electrodes (second group) that output the second transmission pulse signal. Moreover, the power supply of the detection circuit 30 is turned on as needed.

  In the present embodiment, the pulse signal is generated by the controller 10 repeatedly turning on / off (Hi level / Lo level voltage) the output ports P01-P05 at a constant cycle. Therefore, the operation flow after S302 is executed every half of the cycle of the pulse signal. For example, if the pulse frequency is 20 KHz (cycle: 50 μsec), it is executed every 25 μsec. Therefore, the control unit 10 waits for the end of the previous processing cycle (step S302).

In step S303, the output of the electrodes belonging to the first group is switched on / off.
Next, the control unit 10 performs delay processing (step S304) for adding a phase difference between the first transmission pulse and the second transmission pulse (step S304), and then switches on / off the output of the electrodes belonging to the second group (step S305). ).

In step S306, a process of counting the number of output pulse outputs is performed, and when the number of pulse outputs is equal to or greater than the specified number (four times in this embodiment), the control unit 10 ends the pulse output to the electrodes.
If the number of pulse outputs is less than the specified number, the process returns to S302 again to continue the pulse output. (Step S307)

  Next, a flow for changing the duty ratio between the first transmission pulse and the second transmission pulse will be described with reference to FIG. Steps S401 and S402 are the same as steps S301 and S302 in the process of adding a phase difference.

In step S403, the outputs of the electrodes belonging to the first group are compared. When the output of the electrode belonging to the first group is on (Hi level), the output of both the electrode belonging to the first group and the electrode belonging to the second group is inverted (step S404).
Next, a delay process for determining the duty ratio of the second group (step S405) is executed, and the output of the electrodes belonging to the second group is switched on / off (step S406).

  In step S403, if the output of the electrode belonging to the first group is off (Lo level), the output of the electrode belonging to the second group has already been inverted, so the output of only the electrode belonging to the first group is inverted ( Step S407).

  The flow of steps S506 and S507 is the same as steps S408 and S409 of the process of adding a phase difference, respectively.

  Finally, a flow for changing the number of pulses of the first transmission pulse and the second transmission pulse will be described with reference to FIG. Steps S501 to S503 are the same as steps S301 to S303 in the process of adding a phase difference.

  In step S504, the number of pulses output to the electrodes belonging to the second group (number of pulses of the second transmission pulse) is compared. For example, when the first transmission pulse number and the second transmission pulse number are balanced 4 times and 3 times, respectively, and the integration output is balanced, if the second transmission pulse number is less than 3, the second transmission pulse number The output of the electrode belonging to the group is inverted (step S305). When the number of second transmission pulses is 3 or more, the output of the electrode belonging to the second group is not inverted.

  In the pulse output counting process in step S506, the number and number of outputs of the first transmission pulse are counted separately.

In step S507, when the pulse output of the group with a small number of electrodes (first group in this embodiment) is equal to or more than the specified number of times (four times in this embodiment), the control unit 10 outputs the pulse output to the electrodes. finish.
If the number of pulse outputs is less than the specified number, the process returns to S502 again, and pulse output is continued. (Step S507)

  The flow of steps S506 and S507 is the same as steps S408 and S409 of the process of adding a phase difference, respectively.

In step S204, when the integral output Vint is equal to or less than the second threshold value Vth2 (step S204; Vint ≦ −Vth), the control unit 10 shifts from the first operation mode to the second operation mode, and in the first operation mode. It is determined that the user's finger or the like has approached any one of the electrodes of the first group, and further grouping is executed for this determination group. In this case, since the number of electrodes included in the determination group is an even number (two), the subsequent processing is the same as the processing after step S6 of the first embodiment.

In step S204, when the integral output Vint is equal to or higher than the first threshold value Vth1 (step S204; Vint ≧ Vth), the control unit 10 shifts from the first operation mode to the second operation mode and performs the first operation mode in the first operation mode. It is determined that the user's finger or the like has approached one of the two groups of electrodes, and grouping is further performed on this determination group. In this case, the number of electrodes included in the determination group is an odd number (three), but since one of them can apply a fixed potential, the subsequent processing is the same as the processing after step S118 of the second embodiment. It is the same.

  As described above, in the third embodiment, the integral output can be balanced by adjusting the induced voltage output of each electrode even when the number of electrodes is an odd number when the first operation mode is executed.

  In the above-described embodiment, the group specified by the first operation mode is further divided into groups in the second operation mode to narrow down the electrodes close to the user's finger or the like. For each of the plurality of electrodes in the group specified by the operation mode, detection processing similar to that in the third operation mode may be sequentially performed to specify one electrode that is close to the user's finger or the like. .

1 Remote control 10 Control unit 20 Electrode (detection unit)
30 Processing circuit

Claims (2)

Pulse output means for outputting a pulse signal of a predetermined frequency;
A detection unit configured to have a transmission electrode and a reception electrode which are arranged close to each other and are electrostatically coupled, and the reception electrode outputs an induced voltage output when a pulse signal is applied to the transmission electrode; ,
Amplifying means for amplifying the induced voltage output received from the receiving electrode and outputting an amplified output;
Inverting means for inverting the polarity of the amplified output received from the amplifying means and outputting an inverted output;
Integration means for alternately selecting and integrating the amplified output and the inverted output in synchronization with the pulse signal, and outputting an integrated output;
In a capacitive touch sensor comprising: a determination unit that determines proximity of a human body to the detection unit based on an integration output received from the integration unit.
A plurality of the detection units;
The plurality of receiving electrodes constituting the plurality of detection units are electrically connected to each other,
The pulse output means, for each of a plurality of transmission electrodes constituting the plurality of detection units,
A phase difference between a first output mode in which a first transmission pulse signal having substantially the same phase as the pulse signal is applied and the first transmission pulse signal after the polarity of the pulse signal is inverted is less than ± 90 °. A second output mode for applying a second transmission pulse signal,
The capacitive touch sensor includes a first operation mode for detecting that a human body has approached any of the plurality of detection units, and in the first operation mode,
The pulse output means divides the plurality of detection units into a first group and a second group, and sends the first transmission pulse signal to the transmission electrodes of the detection units belonging to the first group in the first output mode. Applying the second transmission pulse signal in the second output mode to the transmission electrodes of the detectors belonging to the second group,
The integrating means calculates the integrated output by integrating the amplified output and the inverted output alternately in synchronization with the pulse signal and the inverted pulse signal,
The determination unit determines that any of the plurality of detection units has approached a human body when the integrated output is greater than or equal to a first threshold value on a positive side or less than or equal to a second threshold value on a negative side with respect to a reference value. When the integrated output is smaller than the first threshold and larger than the second threshold, it is determined that none of the plurality of detection units has a human body approaching the capacitive touch. Sensor. Pulse output means for outputting a pulse signal of a predetermined frequency;
A detection unit configured to have a transmission electrode and a reception electrode which are arranged close to each other and are electrostatically coupled, and the reception electrode outputs an induced voltage output when a pulse signal is applied to the transmission electrode; ,
Amplifying means for amplifying the induced voltage output received from the receiving electrode and outputting an amplified output;
Inverting means for inverting the polarity of the amplified output received from the amplifying means and outputting an inverted output;
Integration means for alternately selecting and integrating the amplified output and the inverted output in synchronization with the pulse signal, and outputting an integrated output;
In a capacitive touch sensor comprising: a determination unit that determines proximity of a human body to the detection unit based on an integration output received from the integration unit.
A plurality of the detection units;
The plurality of receiving electrodes constituting the plurality of detection units are electrically connected to each other,
The pulse output means, for each of a plurality of transmission electrodes constituting the plurality of detection units,
A first output mode in which a first transmission pulse signal having substantially the same phase as the pulse signal is applied; and a second transmission pulse signal in which the duty ratio of the pulse is changed after inverting the polarity of the pulse signal. 2 output modes,
The capacitive touch sensor includes a first operation mode for detecting that a human body has approached any of the plurality of detection units, and in the first operation mode,
The pulse output means divides the plurality of detection units into a first group and a second group, and sends the first transmission pulse signal to the transmission electrodes of the detection units belonging to the first group in the first output mode. Applying the second transmission pulse signal in the second output mode to the transmission electrodes of the detectors belonging to the second group,
The integrating means calculates the integrated output by integrating the amplified output and the inverted output alternately in synchronization with the pulse signal and the inverted pulse signal,
The determination unit determines that any of the plurality of detection units has approached a human body when the integrated output is greater than or equal to a first threshold value on a positive side or less than or equal to a second threshold value on a negative side with respect to a reference value. When the integrated output is smaller than the first threshold and larger than the second threshold, it is determined that none of the plurality of detection units has a human body approaching the capacitive touch. Sensor.