JP4552640B2 - Capacitive input device - Google Patents

Description

  The present invention relates to a touch switch that is a capacitive input device.

  FIG. 7 is a block diagram of an overall configuration of an induction heating cooker provided with a conventional general capacitance type input device, FIG. 10 is an overall configuration diagram, and FIG. 11 is a sectional view of an electrode portion.

  Conventionally, an electrostatic capacitance type input device of this kind of induction heating cooker has a surface of a top plate 23 made of crystallized glass with an outer periphery 21 covered with a metal frame 22 as shown in FIG. The electrode 24 is configured, and the electrode 24 is also configured on the back surface of the top plate 23. The electrode 24 on the back surface is connected to the detection means 28 via the contact terminal 25.

  In FIG. 11, the electrodes 24 arranged on the front and back of the top plate 23 are provided at opposing positions to form a capacitance. At this time, when the human body touches the surface electrode 24, the surface electrode 24 is connected to the ground via an equivalent circuit of the human body. At this time, the change in the potential of the electrode 24 is detected, and it is determined that the human body has operated the switch of the sub operation unit which is the electrode 24.

  The flow of signal processing at this time will be described with reference to FIG. 7 of the block diagram, FIG. 8 of the timing chart showing the operation, and FIG. 9 of the timing chart showing the operation when affected by noise.

  In FIG. 7, first, an oscillation means 26 serving as a reference is constituted by an electronic circuit or a microcomputer. The oscillation means 26 has an oscillation frequency of 400 kHz and is connected to the electrode 24 through a capacitor 27. When the human body touches the electrode 24, the potential changes, and as shown in FIG. 8, the operation change of the first electrode voltage is a determination voltage width V1 that is a predetermined voltage change width or more and a determination time that is a predetermined time or more. The change over time T1 or more is read by the detection means 28, and it is determined that the switch input has been accepted.

  However, at this time, if the radio wave source 30 such as a radio or television is amplified and applied by a structure such as a building, or if another strong electric field exists nearby, the electrode 24 is affected and the detection means 28 Thus, there is a problem that the change in potential (operating) due to the touch of the human body is not known.

  As shown in FIG. 9, when the noise is superimposed, the potential of the reference of the input change fluctuates when the noise is superimposed. The voltage Vref of the difference between the reference potential and the potential change as a result of touching the human body in a state where noise is superimposed in the first place is what originally can be determined by the change width Von from the potential of Since it is smaller than the power criterion V1, it is erroneously determined that the human body is not touching. Therefore, as shown in FIG. 7, in many cases, a filter circuit 29 generally called a band pass filter is inserted in the signal path, and signals other than the basic oscillation frequency are removed and input to the detection means 28. (For example, refer to Patent Document 1).

Alternatively, the change width is limited to a predetermined range, and other cases are determined as external noise, or the voltage change duration is read as described above, and it is determined as external noise if the change is a short time. There are also examples (see, for example, Patent Document 2).
JP 7-225106 A JP-A-5-175820

  However, in the configuration of the conventional capacitive input device shown in FIG. 7, all the electrodes 24 constituted by a plurality of electrodes for performing an input operation of a plurality of contents when affected by noise. In addition, it is necessary to determine whether the filter circuit 29 for preventing noise is necessary, and whether the input signal is noise or is caused by contact with the human body. It had the problem of being.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a capacitance-type input device that can perform a stable operation even in a situation that is constantly affected by noise with a simple configuration.

  In order to solve the above-described problems, a capacitance-type input device according to the present invention includes an oscillating unit that oscillates at a predetermined frequency, a first electrode connected to the oscillating unit via a capacitor, and the first electrode Detecting means for determining that an input has been received by detecting that the potential has changed by a predetermined potential width ΔV1 or more during a period of time equal to or longer than a predetermined time ΔT1, a second electrode not connected to the oscillating means, Detection means for measuring the voltage of the second electrode, and when the voltage detected by the detection means exceeds a predetermined voltage V2, the predetermined potential width ΔV1 of the detection means is a predetermined value Δ smaller than the predetermined potential width ΔV1. And control means for changing to V3.

  This makes it possible to separately determine whether or not the current situation is subject to external electric field noise by the second electrode, and based on the result, take into account the energy of the noise source and capture changes in it sensitively. Thus, the switch operation of the capacitance type input device is determined, and the influence of the noise source can be eliminated.

  The capacitance type input device of the present invention includes an oscillation unit that oscillates at a predetermined frequency, a first electrode connected to the oscillation unit via a capacitor, and a reference potential that is a potential of the first electrode. A detection means for determining that an input has been received by detecting that the voltage has changed by a predetermined potential width ΔV1 or more from V0 for a period of a predetermined time ΔT; a second electrode not connected to the oscillation means; Detection means for measuring the voltage of the second electrode, and control for updating the voltage of the first electrode at that time as a reference potential V0 when the voltage detected by the detection means exceeds a predetermined voltage V2. Means.

  As a result, whether or not the current situation is a situation where external electric field noise is received by the second electrode is separately determined, and the reference potential is changed in consideration of the energy of the noise source based on the result. Even under circumstances, the switch operation of the capacitive input device is judged by sensitively detecting changes caused by contact with the human body, and can be made unaffected by noise sources.

  Further, the capacitance type input device of the present invention includes an oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and the potential of the first electrode for a predetermined time Δ. A detecting means for judging that an input has been received by detecting that the voltage has changed by a predetermined potential width ΔV1 or more during a period of T1 or more; a second electrode not connected to the oscillating means; and a second electrode Detection means for measuring the voltage, and control means for changing the predetermined time width of the detection means to a predetermined value ΔT2 smaller than ΔT1 when the voltage detected by the detection means exceeds the predetermined voltage V2 are provided. Is.

  This makes it possible to separately determine whether or not the current situation is subject to external electric field noise by the second electrode, and change the reference reception time in consideration of the energy of the noise source according to the result. The switch operation of the capacitive input device is determined by sensitively detecting changes due to contact with the human body even under noise conditions, and can be made unaffected by noise sources.

  As described above, according to the capacitive input device of the configuration of the present invention, when affected by noise, it is determined whether there is noise by taking out only the influence of the electric field in the use environment of the device, The influence of noise can be reliably prevented with a simple configuration, and malfunction can be prevented and stable operation can be performed.

  According to a first aspect of the present invention, there is provided an oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and a predetermined potential during a period in which the potential of the first electrode is equal to or greater than a predetermined time ΔT1 Detecting means for determining that an input has been received by detecting that the width ΔV1 or more has changed, a second electrode not connected to the oscillating means, and a detecting means for measuring the voltage of the second electrode By providing control means for changing the predetermined potential width ΔV1 of the detection means to a predetermined value ΔV3 smaller than the predetermined potential width ΔV1 when the voltage detected by the detection means exceeds the predetermined voltage V2, In the noise environment, the acceptance reference voltage width is made small and sensitive so as not to be affected by noise caused by the electric field in the use environment.

  In the second invention, in particular, the control means of the first invention changes the predetermined potential width ΔV1 in accordance with the magnitude of the predetermined voltage V2 detected by the detection means. The acceptance reference voltage width is small and sensitively changed depending on the noise level so as not to be affected by noise caused by the electric field in the use environment.

  According to a third aspect of the present invention, an oscillation means that oscillates at a predetermined frequency, a first electrode connected to the oscillation means via a capacitor, and a reference potential V0 that is the potential of the first electrode, a predetermined time ΔT In the period described above, the detection means for determining that the input has been received by detecting that the voltage has changed by a predetermined potential width ΔV1 or more, the second electrode not connected to the oscillation means, and the voltage of the second electrode And a control means for updating the voltage of the first electrode as a reference potential V0 when the voltage detected by the detection means exceeds a predetermined voltage V2. In a noisy environment, by changing the acceptance reference potential each time depending on the noise level, it is possible to reliably detect potential changes due to the human body without being affected by noise caused by the electric field in the usage environment. One in which the.

  In the fourth aspect of the invention, in particular, when the voltage detected by the detection means falls below the predetermined voltage V2, the control means of the third aspect of the invention updates the voltage of the electrode at that time as the reference potential V0. By changing the acceptance reference potential according to the noise level depending on the noise level in a noisy environment, the change in potential due to the human body is ensured without being affected by the noise caused by the electric field in the usage environment. It is intended to be detected.

  According to a fifth aspect of the present invention, there is provided an oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and a predetermined potential during a period in which the potential of the first electrode is not less than a predetermined time ΔT1. Detecting means for determining that an input has been received by detecting that the width ΔV1 or more has changed, a second electrode not connected to the oscillating means, and a detecting means for measuring the voltage of the second electrode And a control means for changing the predetermined time width of the detection means to a predetermined value ΔT2 smaller than ΔT1 when the voltage detected by the detection means exceeds the predetermined voltage V2, in a noisy environment. By changing the reception reference electric time according to the noise level, it is possible to reliably detect a change in electric potential due to a human body without being affected by noise caused by an electric field in a use environment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing signal processing of the capacitive input device according to the first embodiment of the present invention.

  As shown in FIG. 1, normally, when a rectangular wave of 400 kHz, for example, is applied from the oscillating means 6 to the first electrode 4 via the capacitor 7, a predetermined reference voltage corresponding to the capacitor capacity and the oscillation frequency is determined. In this state, when the human body touches the first electrode 4 directly or indirectly through a conductive material, the voltage of the first electrode 4 changes due to the impedance of the human body coupled to the ground. This change is caught by the detection means 8, and it is determined that the switch has been accepted when a change in the predetermined voltage width occurs for a predetermined time. Up to this point, the operation is the same as that of the conventional example.

  At this time, for example, when a strong electric field is emitted from the radio wave source 10, the radio wave noise taken out by the detection means 12 by receiving the electric field of the external noise at the second electrode 11 installed in a portion that is not touched by the human body. Is converted into voltage, and if the magnitude is greater than or equal to a predetermined magnitude, the control means 14 changes the detection voltage width of the detection means 8.

  FIG. 4 is a timing chart showing the operation of the voltage of the first electrode 4 and the voltage of the second electrode 11 at this time.

  In the first electrode voltage, the original reference potential V0 is raised by noise energy. Originally, it is determined that the human body has operated the first electrode 4 when the voltage changes from the stored reference potential by the width of the voltage V1 or more. However, as shown in the figure, the voltage Von width changes when the human body touches. However, since the difference from the reference potential is the voltage width Vref and V1> Vref, it cannot be determined that the switch has been received by mistake. Therefore, since the second electrode voltage is measured by the detecting means 12 and exceeds the predetermined voltage V2, if the control means 14 issues an instruction to change the detected voltage width V1, the detected voltage width is set to V3 smaller than V1. At this time, V3 <Vref, and it can be determined that the switch has been accepted. Therefore, in the noise environment, the acceptance reference voltage width is made small and sensitive so as not to be affected by the noise caused by the electric field in the use environment.

  Specifically, the oscillation means 6 for changing the oscillation frequency, the control means 14 and the detection means 12 are generally configured by a microcomputer.

(Embodiment 2)
According to the second embodiment of the present invention, the magnitude of the radio noise extracted by the detection means 12 is converted into a voltage, as in the first embodiment of the present invention shown in FIG. In accordance with the magnitude, that is, the magnitude of radio noise, the control means 14 changes the detection voltage width of the detection means 8 each time. Therefore, in the noise environment, the acceptance reference voltage width is small and sensitively changed depending on the noise level so as not to be affected by noise caused by the electric field in the use environment.

(Embodiment 3)
According to the third embodiment of the present invention, as shown in the block diagram of the signal processing of FIG. 2, for example, when a strong electric field is emitted from the radio wave source 10, it is installed in a portion that is not touched by the human body. The second electrode 11 receives an electric field of external noise and converts the magnitude of the radio noise taken out by the detection means 12 into a voltage. Since the magnitude exceeds the predetermined voltage V2, the control is performed. The reference potential V0 for measuring the detection voltage width of the detection means 8 is changed by the means 14.

  FIG. 5 shows a timing chart showing the operation of the voltage of the first electrode 4 and the voltage of the second electrode 11 at this time.

  At the first electrode voltage, the original reference potential V0 is raised by the energy of noise (V20). Originally, it is determined that the human body has operated the first electrode 4 when the voltage changes from the stored reference potential by the width of the voltage V1 or more. However, as shown in the figure, the voltage Von width changes when the human body touches. However, since the difference from the reference potential is the voltage width Vref and the relationship of V1> Vref, it cannot be determined that the switch has been received by mistake. Therefore, since the second electrode voltage is measured by the detection means 12 and exceeds the predetermined voltage V2, an instruction to change the reference voltage V0 of the detection voltage width V1 to the potential V20 is issued by the control means 14. If so, since the reference potential is changed during the determination as shown in FIG. 5, at this time, V1 <Vref = Von and it can be determined that the switch has been accepted. Therefore, in a noisy environment, the acceptance reference potential is changed each time depending on the noise level, so that a change in potential due to the human body is reliably detected without being affected by noise caused by the electric field in the use environment. .

  Specifically, the control means 14 for changing the reference potential and the detection means 12 are generally constituted by a microcomputer.

(Embodiment 4)
According to the fourth embodiment of the present invention, as shown in the block diagram of signal processing in FIG. 2, for example, when a strong electric field is emitted from the radio wave source 10, it is installed in a portion that is not touched by the human body. The second electrode 11 receives an electric field of external noise and converts the magnitude of the radio noise taken out by the detection means 12 into a voltage. Since the magnitude exceeds the predetermined voltage V2, the control is performed. If the reference potential V0 for measuring the detection voltage width of the detection means 8 is changed by the means 14, and the magnitude of the radio noise extracted by the detection means 12 returns to V4 or less, which is less than the predetermined magnitude V2, the control is performed. The reference potential for measuring the detection voltage width of the detection means 8 is returned by the means 14 to the original value V0.

  FIG. 5 shows a timing chart showing the operation of the voltage of the first electrode 4 and the voltage of the second electrode 11 at this time.

  The reference voltage V20 is returned to the original (V0) when the voltage (V2 or higher) raised by the noise to the second electrode decreases (V4). Therefore, in a noisy environment, by changing the acceptance reference potential depending on the noise level depending on the noise level, it is possible to reliably detect changes in the potential due to the human body without being affected by noise caused by the electric field in the usage environment. It is a thing.

  Specifically, the control means 14 for changing the reference potential and the detection means 12 are generally constituted by a microcomputer.

(Embodiment 5)
According to the fifth embodiment of the present invention, as shown in the signal processing block diagram of FIG. 3, for example, when a strong electric field is emitted from the radio wave source 10, it is installed in a portion that is not touched by the human body. The second electrode 11 receives an electric field of external noise and converts the magnitude of the radio noise taken out by the detection means 12 into a voltage. Since the magnitude exceeds the predetermined voltage V2, the control is performed. The means 14 changes the detection time width T1 of the detection means 8.

  FIG. 6 shows the operation of the voltage of the first electrode 4 and the voltage of the second electrode 11 at this time.

  In the first electrode voltage, the original potential is raised by noise energy. Originally, it is determined that the human body has operated the first electrode 4 if it changes for a period of time width T1 or more from the stored reference potential. However, as shown in the figure, the human body touches for a period of time width T1 or more. Even if the electrode potential changes, the first electrode 4 touched by the human body is affected by the electric field noise at that time, and if the potential detected by the detection means 8 changes midway, it is erroneously accepted. It cannot be judged.

  At that time, when the influence of the electric field noise received by the second electrode 11 is converted into a voltage by the detection means 12, and the voltage is equal to or higher than the predetermined voltage V2, a key is received as shown in FIG. It is determined that the switch is received by changing the time for determining that the switch has been changed from T1 to a time T2 shorter than T1. Under a noisy environment, by changing the acceptance reference electric time according to the noise level, a change in electric potential due to a human body is reliably detected without being affected by noise caused by an electric field in the use environment.

  Specifically, the oscillation means 6 for changing the oscillation frequency, the control means 14 and the detection means 12 are generally configured by a microcomputer.

  As described above, the capacitance-type input device according to the present invention can reliably prevent the influence of the electric field in the usage environment with a simple configuration. Applicable to general applications such as switches.

The block diagram which shows the structure of the electrostatic capacitance type input device in Embodiment 1 and 2 of this invention The block diagram which shows the structure of the electrostatic capacitance type input device in Embodiment 3 and 4 of this invention The block diagram which shows the structure of the electrostatic capacitance type input device in Embodiment 5 of this invention. Timing chart showing the operation of the capacitive input device according to the first and fourth embodiments of the present invention Timing chart showing the operation of the capacitive input device according to the third embodiment of the present invention. Timing chart showing the operation of the capacitive input device according to the fifth embodiment of the present invention. The block diagram which shows the whole structure of the electrostatic capacitance type input device of a prior art example Timing chart showing the operation of a conventional capacitive input device Timing chart showing the operation of the conventional capacitive input device when affected by noise Overall configuration diagram of an induction heating cooker that employs a conventional capacitive input device Sectional drawing of the electrode part of the induction heating cooking appliance which employ | adopted the electrostatic capacitance type input device of the prior art example

Explanation of symbols

4 First electrode of top plate of induction cooking device adopting capacitive input device 6 Oscillating means 7 Capacitor 8 Detection means 10 Radio wave source 11 Second electrode 12 Detection means 14 Control means

Claims (5)

Oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and the potential of the first electrode changed by a predetermined potential width ΔV1 or more during a period of a predetermined time ΔT1 or more. Detecting means for detecting that an input has been received; a second electrode not connected to the oscillating means; a detecting means for measuring a voltage of the second electrode; and detecting by the detecting means And a control means for changing the predetermined potential width ΔV1 of the detecting means to a predetermined value ΔV3 smaller than the predetermined potential width ΔV1 when the applied voltage exceeds the predetermined voltage V2. 2. The capacitance type input device according to claim 1, wherein the control means changes the predetermined potential width ΔV1 in accordance with the magnitude of the predetermined voltage V2 detected by the detection means. An oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and a reference potential V0 that is a potential of the first electrode, for a predetermined time ΔT or more for a predetermined potential. Detecting means for determining that an input has been received by detecting that the width ΔV1 or more has changed, a second electrode not connected to the oscillating means, and a detecting means for measuring the voltage of the second electrode A capacitance type input device provided with control means for updating the voltage of the first electrode as a reference potential V0 when the voltage detected by the detection means exceeds a predetermined voltage V2. 4. The electrostatic capacity according to claim 3, wherein when the voltage detected by the detection means falls below a predetermined voltage V4, the control means updates the voltage of the first electrode at that time as the reference potential V0. Expression input device. Oscillating means that oscillates at a predetermined frequency, a first electrode connected to the oscillating means via a capacitor, and the potential of the first electrode changed by a predetermined potential width ΔV1 or more during a period of a predetermined time ΔT1 or more. Detecting means for detecting that an input has been received; a second electrode not connected to the oscillating means; a detecting means for measuring a voltage of the second electrode; and detecting by the detecting means And a control means for changing the predetermined time width of the detecting means to a predetermined value ΔT2 smaller than ΔT1 when the applied voltage exceeds the predetermined voltage V2.

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