JP2016012819A - Detection device and input device using the same detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device capable of improving detection sensitivity to detect the hand or the like in a gesture operation or the like, and an input device.SOLUTION: A varactor diode VD is arranged in an LC resonance part 11 of an oscillation circuit 10. An antenna part 2 is arranged on a power supply path 13 from a constant voltage power supply Vvd to the varactor diode VD. An AC electric field is formed in a space from the antenna part 2 in accordance with an AC signal generated by the oscillation circuit 10. When a human body approaches the antenna part 2, the frequency of the AC signal changes in accordance with a capacitance change detected by the antenna part 2. Furthermore, when the human body approaches the antenna part 2, the fluctuation of a voltage occurs in the power supply path 13, and the capacitance of the varactor diode VD changes. The change of the frequency of the AC signal is amplified in accordance with the change of the capacitance of the varactor diode VD.

Description

  The present invention relates to a detection device provided with an antenna section for transmitting an alternating current signal and detecting the approach of a human body and an input device using the detection device.

  As an electrostatic capacitance type detection device, there is one that can detect a gesture operation of moving a human hand or finger in space.

  The detection device described in Patent Document 1 is provided with a signal electrode and a ground electrode, and the ground electrode is connected to the gate terminal of the field effect transistor. When a signal of a predetermined frequency is given from the microcontroller to the gate terminal of the field effect transistor, the electric field coupling capacitance C1 between the electrodes, the coupling capacitances C2 and C3 between the hand and each electrode, and the coupling from the hand to the ground Exponential charging / discharging occurs due to the influence of the capacity C4.

  Since there is a time difference in charging / discharging depending on whether or not there is a coupling capacitance C2, C3 between the hand and each electrode, detecting whether or not a gesture operation is being performed by detecting this time difference. Can do.

Special table 2012-509610 gazette

  In Patent Document 1, it is explained that a change in capacitance at the gate terminal of a field effect transistor is indispensable for the sensitivity for detecting the approach of the hand, and that this change in capacitance appears as a charge / discharge time difference. ing.

  That is, the sensitivity of the detection device of Patent Document 1 is determined by the output characteristics of the field effect transistor and the capacitance detected by the signal electrode connected to the gate terminal of the field effect transistor. In order to increase the frequency, means for further amplifying the amplitude of the frequency signal given from the microcontroller to the gate terminal is required.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a detection device that does not require particularly large power and can increase detection sensitivity, and an input device using the detection device.

The present invention provides a detection device provided with an oscillation circuit that generates an AC signal, an antenna unit to which the AC signal is applied, and a detection circuit that detects a change in the frequency of the AC signal.
A voltage variable capacitor is used as an oscillation capacitor of the oscillation circuit, and the antenna unit is provided in a power supply path to the voltage variable capacitor.

  In the present invention, it is preferable that an applied voltage applied to the voltage variable capacitor by the power feeding path is ½ or less of a rated voltage of the voltage variable capacitor.

  According to the present invention, the voltage variable capacitor has a cathode connected to the power supply path and an anode grounded via a bias resistor.

  Further, a DC blocking capacitor is provided between the cathode of the voltage variable capacitor and the oscillation circuit element.

  The input device according to the present invention is characterized in that a plurality of sets of the detection devices are provided, and the antenna units are arranged at intervals.

  Further, the input device can be configured as a display screen provided and the antenna unit disposed at a position sandwiching the display screen.

  In the input device of the present invention, when a part of the human body approaches the antenna unit, the capacitance sensed by the antenna unit changes, and the AC signal generated by the oscillation circuit changes. Further, since the antenna unit is provided in the power supply path to the voltage variable capacitor, when a human body approaches the antenna unit, voltage ripple (pulsation component) is generated in the antenna unit, and the voltage variable capacitor changes. The change in the voltage variable capacitance amplifies the change in the frequency of the AC signal, thereby increasing the sensitivity for detecting a part of the human body.

  In particular, when the applied voltage applied to the voltage variable capacitor by the power feeding path is set to ½ or less of the rated voltage of the voltage variable capacitor, the change in the voltage variable capacitor when the ripple occurs increases. Detection sensitivity is further increased.

  Thus, the detection device of the present invention can increase the sensitivity for detecting the approach of the human body without particularly increasing the power supply.

The circuit block diagram of the detection apparatus of embodiment of this invention, FIG. 1 is a circuit diagram showing details of the oscillator and the detection circuit shown in FIG. A diagram showing the characteristics of the variable voltage capacitor; (A) is an output waveform diagram showing a change in the detection output of the comparative example, (B) is an output waveform diagram showing a change in the detection output of the embodiment, It is an output waveform diagram which shows the change of the detection output in the input device carrying multiple said detection apparatuses, (A) shows gesture operation to S1 direction in FIG. 6, (B) shows gesture operation to S2 direction. Show, Front view showing an input device equipped with a plurality of antenna units,

FIG. 1 is a circuit block diagram showing a detection device 1 according to an embodiment of the present invention.
A detection apparatus 1 shown in FIG. 1 includes an antenna unit 2, an oscillation circuit 10, a detection circuit 3, a low-pass filter 4, a notch filter 5, and a low-pass filter 6.

  As illustrated in FIG. 2, the oscillation circuit 10 includes an LC resonance unit 11 and an operational amplifier 12. The LC resonance unit 11 is a parallel resonance circuit in which inductances (coils) L1 and L2 and capacitors (capacitors) C2, C4, and C5 are provided as oscillation circuit elements, and is a voltage variable capacitor in a part of the parallel unit. A varactor diode VD is connected.

  The oscillation circuit 10 is provided with a power supply path 13 from the constant voltage power supply Vvd to the cathode of the varactor diode VD. The antenna unit 2 is provided in the middle of the power feeding path 13.

  A DC blocking capacitor C1 is provided between the cathode of the varactor diode VD and the parallel portion of the inductance L1 and the capacitor C2 of the oscillation circuit element. The oscillation circuit elements L1 and C2 and the operational amplifier 12 are provided with a coupling capacitor C3.

  The varactor diode VD has a cathode connected to the power supply path 13 and an anode grounded via a bias resistor Ra and a bypass capacitor C4. A reverse voltage Vc is applied to the varactor diode VD, and this reverse voltage Vc is determined by the voltage of the constant voltage power supply Vvd and the voltage of the bias resistor Ra. With these two voltages, a very small voltage is applied to the varactor diode VD.

  FIG. 3 shows the variable capacitance characteristics of the varactor diode VD used in the LC resonance unit 11. The horizontal axis represents the reverse voltage Vc, which is a negative voltage whose absolute value increases in the right direction. The vertical axis is the capacity.

  The varactor diode VD has a capacitance that decreases quadratically or exponentially as the absolute value of the reverse voltage Vc increases. In contrast, it is set in a region where the fluctuation of the capacity becomes large. For this purpose, the absolute value of the reverse voltage Vc is preferably set to 1/2 (VD / 2) or less of the rated voltage of the varactor diode VD. Further, the reverse voltage Vc is more preferably set in a region very close to 0V. By setting in this way, it is possible to expand the width of the capacitance change with respect to the voltage change of the reverse voltage Vc.

  The low-pass filters 4 and 6 shown in FIG. 1 allow low-frequency components of the detection signal detected by the detection circuit 3 to pass therethrough, and the cut frequency is about 20 Hz. The notch filter 5 removes a noise component, for example, a frequency component of about 50 Hz is removed.

Next, the operation of the detection device 1 will be described.
In the oscillation circuit 10, the LC resonance unit 11 resonates at a frequency determined by the inductance and the capacitance, and an AC signal having this resonance frequency is generated. The AC signal is given to the antenna unit 2, and an electric field based on the AC signal is generated in the space from the antenna unit 2. When a finger or hand that is a part of the human body approaches the antenna unit 2, the frequency of the AC signal changes due to capacitive coupling between the antenna unit 2 and the finger or hand.

  In the detection circuit 3, the frequency component of the AC signal is removed (the frequency is classified), and a detection output corresponding to the change in the frequency is obtained.

  Moreover, the antenna part 2 is provided in the middle of the electric power feeding path | route 13 from the constant voltage power supply Vvd to the varactor diode VD. When a human hand or finger approaches the antenna unit 2 that is a part of the power supply path 13, the current flowing through the antenna unit 2 changes, and a nipple (pulsation component) is generated in the voltage of the power supply path 13. Since the reverse voltage Vc applied to the varactor diode VD varies due to this voltage nipple, the capacitance of the varactor diode VD varies. As shown in FIG. 3, when the reverse voltage Vc is set to a region close to 0 volts in the region of VD / 2 or less that is ½ of the rated voltage, the capacitance of the varactor diode VD accompanying the change of the reverse voltage Vc. It is also possible to change the capacitance by a width of 40-50 pF by, for example, a nipple given to the power supply path 13.

  Since the resonance frequency of the resonance circuit 11 fluctuates due to the change in capacitance of the varactor diode VD, the change in frequency due to the change in capacitance of the varactor diode VD is further added to the change in frequency when the antenna unit 2 detects the change in capacitance. The fluctuation of the frequency of the AC signal generated by the oscillation circuit 10 becomes large, and the detection output detected by the detection circuit 3 is amplified.

  4A and 4B are waveform diagrams obtained by measuring the detection output obtained from the detection circuit 3 with an oscilloscope when a hand is passed forward (upward) of the antenna unit 2. 4A shows a waveform of a detection output when a fixed capacitor is used instead of the varactor diode VD, and FIG. 4B shows an embodiment in which the varactor diode VD is provided in the LC resonance unit 11. The waveform of the detection output is shown.

  The detection output in FIG. 4A is based on the change in frequency of the AC signal due to only the change in capacitance detected by the antenna unit 2, and the level of the detection output is small. On the other hand, in FIG. 4B, the change in the frequency of the AC signal due to the capacitance change detected by the antenna unit 2 and the change in the frequency of the AC signal based on the ripple of the voltage applied to the power supply path 13 are added. Detection output. Therefore, the level of the detection output is amplified as compared with the waveform of FIG.

FIG. 6 is a front view showing the input device 20 on which the detection device 1 is mounted.
The input device 20 is used as a portable information terminal device, a mobile phone device, a game machine, and the like, and a display screen 22 is provided at the center of the frame body 21. An image generated by a color liquid crystal panel or the like is displayed on the display screen 22, and a translucent touch pad such as a capacitance type or an electric resistance type is superimposed on the display screen 22. An input operation can be performed by touching the display screen 22 with a finger or the like while viewing the display image.

  Four sets of the detection devices 1 are mounted on the input device 20, and an antenna portion provided in each detection device 1 is embedded in a frame body 21 around the display screen 22. In FIG. 6, the antenna unit disposed on the left side of the display screen 22 is denoted by reference numeral 2 a, and the antenna unit disposed on the right side is denoted by 2 b. In addition, the antenna unit disposed on the upper side of the display screen 22 is denoted by reference numeral 2c, and the antenna unit disposed on the lower side is denoted by reference numeral 2d.

  The upper waveforms in FIGS. 5A and 5B show changes in detection output detected by the antenna unit 2a, and the lower waveforms show changes in detection output detected by the antenna unit 2b.

  FIG. 5A is a space on the near side of the input device 20 shown in FIG. 6. When the gesture operation for moving the hand in the S1 direction from the left side to the right side is performed, the antenna unit 2a and the antenna unit 2b Indicates the detection output. FIG. 5B shows detection outputs of the antenna unit 2a and the antenna unit 2b when a gesture operation for moving the hand from the right side to the left side in the S2 direction is performed.

  In FIG. 5A, the change in the detection output by the antenna unit 2a precedes the change in the detection output by the antenna unit 2b, and it can be recognized that this is a gesture operation in the right direction. In FIG. 5B, the change in the detection output by the antenna unit 2b precedes the change in the detection output by the antenna unit 2a, and it can be recognized that this is a gesture operation in the left direction. It is also possible to calculate the speed of gesture operation by hand from right to left or from left to right by measuring the time difference between the change in detection output by the antenna unit 2a and the change in detection output by the antenna unit 2b. is there.

  Similarly, from the change in the detection output from the antenna unit 2c located on the upper side of the display screen 22 and the change in the detection output from the antenna unit 2d located on the lower side of the display screen 22, the hand or the like is directed from the top to the bottom. The gesture operation when moved in the S3 direction and the gesture operation moved in the S4 direction from the lower side to the upper side can be detected.

  The input device using the detection device of the present invention may be equipped in a keyboard device of a personal computer in addition to a portable information terminal device, or a human body that detects the approach of the human body and starts various electronic devices. It can also be used for detection devices.

DESCRIPTION OF SYMBOLS 1 Detection apparatus 2 Antenna part 3 Detection circuit 4,6 Low pass filter 5 Notch filter 10 Oscillation circuit 11 LC resonance part 12 Operational amplifier 13 Feeding path 20 Input device 21 Frame 22 Screen VD Varactor diode (voltage variable capacity)

Claims (6)

In a detection device provided with an oscillation circuit that generates an AC signal, an antenna unit to which the AC signal is applied, and a detection circuit that detects a change in the frequency of the AC signal,
A detection device, wherein a voltage variable capacitor is used as an oscillation capacitor of the oscillation circuit, and the antenna unit is provided in a power supply path to the voltage variable capacitor.   The detection device according to claim 1, wherein an applied voltage applied to the voltage variable capacitor by the power feeding path is ½ or less of a rated voltage of the voltage variable capacitor.   The detection apparatus according to claim 2, wherein the voltage variable capacitor has a cathode connected to the power supply path and an anode grounded via a bias resistor.   The detection device according to claim 3, wherein a DC blocking capacitor is provided between the cathode of the voltage variable capacitor and the oscillation circuit element.   5. An input device comprising: a plurality of sets of detection devices according to claim 1; and a plurality of antenna units arranged at intervals.   The input device according to claim 5, wherein a display screen is provided, and the antenna unit is disposed at a position sandwiching the display screen.