JP2024007007A - detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve sensitivity to an object to be detected in a detection system.

SOLUTION: A detection system 1 includes: a capacitive sensor 12 having a plurality of electrodes 14; a conductor 20; a first signal output circuit 31 that outputs, to the plurality of electrodes 14, a driving signal Sg generated by driving voltage Vg which fluctuates at a predetermined period; a second signal output circuit 32 that outputs, to the conductor 20, an opposite phase signal Sr generated by opposite phase voltage Vr of opposite phase to a phase of driving voltage Vg; a detection signal generating circuit 33 that generates a detection signal Sd in accordance with a capacitance of the electrode 14; and a detection circuit 34 that detects a change in the detection signal Sd in accordance with the induced voltage generated on an operator M by the conductor 20 to which the opposite phase signal Sr is supplied.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

TECHNICAL FIELD This disclosure relates to detection systems.

In recent years, capacitive touch panels have attracted attention. For example, in the input system disclosed in Patent Document 1, a touch panel is stacked on a dual-view liquid crystal display device to form a touch panel display.

JP2009-217731A

A capacitive detection system accurately detects a detection target such as an operator's finger when the detection target contacts a detection surface. In addition, by adjusting the detection voltage and increasing the size of the electrodes, the capacitive detection system can detect the detection target even when the detection target is several centimeters away without touching the detection surface. can do. However, if the detection target is relatively far from the detection surface, the capacitive detection system cannot detect the detection target. Even in such cases, there is a desire to further improve the sensitivity of the capacitive detection system to the detection target so that the capacitive detection system can detect the detection target.

The present disclosure aims to improve sensitivity to a detection target in a detection system.

The detection system of the present disclosure includes a capacitive sensor having a plurality of electrodes, a conductor, and a drive signal generated by a drive voltage that varies at a predetermined period, and outputs a drive signal to the plurality of electrodes. a first signal output circuit that outputs to the conductor an anti-phase signal generated by an anti-phase voltage that is anti-phase to the phase of the drive voltage; and a second signal output circuit that outputs an anti-phase signal to the conductor, A detection signal generation circuit that generates a signal, and a detection circuit that detects a change in the detection signal according to an induced voltage generated in the operator by the conductor to which the antiphase signal is supplied. .

FIG. 1 is a schematic diagram showing the configuration of a detection system according to a first embodiment. FIG. 2 is a side sectional view schematically showing the configuration of the display panel. FIG. 3 is a plan view of the sensor. FIG. 4 is a diagram showing the waveform of the drive voltage. FIG. 5 is a diagram showing the waveform of the antiphase voltage. FIG. 6 is a diagram showing an equivalent circuit of a circuit that detects a detection target. FIG. 7 is a diagram showing a time chart of the operation of the detection system. FIG. 8 is a diagram showing the waveform of the in-phase voltage. FIG. 9 is a diagram showing the configuration of a detection system according to the third embodiment.

Each embodiment of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the content described in the embodiments below. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the components described below can be combined as appropriate.

Note that the disclosure is merely an example, and any modifications that can be easily made by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of the present disclosure. In addition, in order to make the explanation more clear, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but these are only examples, and the interpretation of this disclosure will be limited. It is not limited. In addition, in this specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

<First embodiment>
FIG. 1 is a schematic diagram showing the configuration of a detection system according to a first embodiment. The detection system 1 is, for example, a car navigation system, and is installed in a vehicle. The detection system 1 includes a display panel 10, a conductor 20, and a control device 30.

FIG. 2 is a side sectional view schematically showing the configuration of the display panel. The display panel 10 includes a display section 11 and a sensor 12.

The display unit 11 is a liquid crystal display having a display surface 11a. The display section 11 includes a liquid crystal display element as a display element. The display section 11 includes a plurality of pixels each having a liquid crystal display element. The display unit 11 displays an image made up of a plurality of pixels in the display area DA of the display surface 11a based on the video signal output from the control device 30. Note that the display section 11 may be, for example, an organic EL display or an inorganic EL display.

The sensor 12 is a capacitance type sensor. Specifically, the sensor 12 is a self-capacitance type sensor. The sensor 12 has a plate shape and detects a detection target located on the detection surface 12a side. The detection target is, for example, the finger of the operator M. Note that the detection target may be a part of the operator M other than the stylus pen and finger.

The sensor 12 is arranged with an air gap AG in between so that the plate surface opposite to the detection surface 12a faces the display surface 11a of the display section 11. Furthermore, the detection area AA of the detection surface 12a overlaps the display area DA in plan view.

The sensor 12 includes a sensor substrate 13, a plurality of electrodes 14, and a cover panel 15. The sensor substrate 13, the electrode 14, and the cover panel 15 are stacked in this order from the display section 11 side toward the detection surface 12a side.

The sensor substrate 13 is a transparent substrate, and is, for example, a glass substrate or a flexible printed circuit (FPC). A shield 13a is arranged on the surface of the sensor board 13 facing the display section 11. The shield 13a suppresses the influence on the capacitance of the electrode 14 from the side opposite to the detection surface 12a.

FIG. 3 is a plan view of the sensor. For the plurality of electrodes 14, a light-transmitting conductive material such as ITO (Indium Tin Oxide) is used, for example. The plurality of electrodes 14 have a square shape when viewed from above, and are arranged in a matrix in the detection area AA on the surface of the sensor substrate 13 on the detection surface 12a side when viewed from above. Specifically, a plurality (5 pieces) are arranged in a first direction D1 perpendicular to the perpendicular to the detection surface 12a, and a plurality (4 pieces) are arranged in a second direction D2 perpendicular to the perpendicular to the detection surface 12a and the first direction D1. has been done. It goes without saying that the shape, arrangement, and number of the plurality of electrodes 14 are not limited to the shape, arrangement, and number shown in FIG. 3. Further, the plurality of electrodes 14 are electrically connected to the control device 30 via wiring L arranged on the sensor substrate 13.

The cover panel 15 shown in FIG. 2 is a light-transmitting protection panel. The cover panel 15 is made of glass, for example. A surface of the cover panel 15 opposite to the plate surface facing the electrode 14 constitutes a detection surface 12a. Cover panel 15 is placed on sensor substrate 13 via adhesive layer OC. For the adhesive layer OC, it is desirable to use a translucent adhesive. The adhesive layer OC may be formed of a translucent film having double-sided adhesiveness, such as OCA (Optical Clear Adhesive).

On the display surface 11a of the display unit 11, images such as buttons for operating the detection system 1 are displayed. When the operator M operates the detection system 1, when a detection target such as a finger of the operator M approaches the detection surface 12a toward the image thereof, the capacitance of the electrode 14 changes. Based on this change in capacitance of the electrode 14, the detection system 1 detects the detection target (details will be described later). Note that the display section 11 and the sensor 12 may be configured integrally. In this case, some of the members such as the electrodes and substrate of the display section 11 may also be used as the substrate of the sensor 12.

The conductor 20 shown in FIG. 1 is sheet-shaped and has electrical conductivity. The conductor 20 is, for example, copper foil. Note that it goes without saying that the conductor 20 is not limited to a sheet shape. The conductor 20 is arranged at a position where an induced voltage is generated in the operator M who operates the sensor 12 by being supplied with an anti-phase signal Sr, which will be described later. The conductor 20 is placed, for example, on the seat 2 of a vehicle.

The control device 30 centrally controls the detection system 1 . The control device 30 is configured by a computer having a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The CPU functions as a functional unit that controls the detection system 1 by executing a program stored in advance in the ROM.

The control device 30 includes a first signal output circuit 31, a second signal output circuit 32, a detection signal generation circuit 33, and a detection circuit 34 as functional units.

The first signal output circuit 31 outputs a drive signal Sg shown in FIG. 7, which will be described later, to the plurality of electrodes 14. The drive signal Sg is a signal for driving the sensor 12. The drive signal Sg is generated by a drive voltage Vg that fluctuates at a first predetermined cycle T1.

FIG. 4 is a diagram showing the waveform of the drive voltage. The drive voltage Vg is an alternating current voltage whose potential fluctuates at a first predetermined period T1. The first predetermined period T1 is derived in advance through experiments or the like so that the detection target can be detected. Drive voltage Vg has an amplitude Hg. The drive signal Sg generated by such a drive voltage Vg is an AC rectangular wave (FIG. 7).

The first signal output circuit 31 outputs the drive signal Sg to the plurality of electrodes 14 at a predetermined second period T2. The second predetermined period T2 is determined in advance through experiments or the like so that the detection target can be detected, and when converted into a frequency, it is, for example, about several kHz to several hundred kHz.

The second signal output circuit 32 outputs an antiphase signal Sr (shown in FIG. 7 described later) generated by an antiphase voltage Vr to the conductor 20.

FIG. 5 is a diagram showing the waveform of the antiphase voltage. The phase of the antiphase voltage Vr is opposite to the phase of the drive voltage Vg. The period of the anti-phase voltage Vr is the same as the period of the drive voltage Vg, which is the first predetermined period T1. Moreover, the amplitude Hr of the anti-phase voltage Vr is equal to the amplitude Hg of the drive voltage Vg shown in FIG. Note that the amplitude Hr of the anti-phase voltage Vr may be larger than the amplitude Hg of the drive voltage Vg. The antiphase signal Sr generated by such an antiphase voltage Vr is an AC rectangular wave like the drive signal Sg (FIG. 7).

The second signal output circuit 32 outputs the opposite phase signal Sr to the conductor 20 in synchronization with the drive signal Sg. That is, the cycle of the anti-phase signal Sr is the second predetermined cycle T2, which is equal to the drive signal Sg.

The detection signal generation circuit 33 generates a detection signal Sd according to the capacitance of the electrode 14. The detection signal generation circuit 33 constitutes an equivalent circuit K of a circuit that detects a detection target.

FIG. 6 is a diagram showing an equivalent circuit of a circuit that detects a detection target. The equivalent circuit K includes an electrode 14, a first switch SW1, a second switch SW2, and a detection signal generation circuit 33. The equivalent circuit K is configured for each of the plurality of electrodes 14. The control device 30 may include the first switch SW1 and the second switch SW2, or the sensor 12 may include the first switch SW1 and the second switch SW2.

When the first switch SW1 is on, the first signal output circuit 31 that outputs the drive signal Sg and the electrode 14 are electrically connected, and the drive signal Sg is supplied to the electrode 14. As a result, the capacitance Ce of the electrode 14 is charged. When the first switch SW1 is off, the first signal output circuit 31 and the electrode 14 are electrically disconnected.

When the second switch SW2 is on, the detection signal generation circuit 33 and the electrode 14 are electrically connected. As a result, the charge of the capacitance Ce of the electrode 14 is transferred to the detection signal generation circuit 33. When the second switch SW2 is off, the detection signal generation circuit 33 and the electrode 14 are electrically disconnected.

The detection signal generation circuit 33 includes an integrating circuit and a reset circuit, and generates the detection signal Sd. The detection signal generation circuit 33 includes a third switch SW3 and a capacitor Cd.

The first switch SW1, the second switch SW2, and the third switch SW3 are controlled by the detection circuit 34 in synchronization with the drive signal Sg, as described later. As a result, in the detection signal generation circuit 33, the capacitor Cd is repeatedly charged and discharged, so that the detection potential Vd fluctuates, and the detection signal Sd is generated (details will be described later).

When the detection target approaches the sensor 12, the capacitance of the electrode 14 changes, causing the detection signal Sd to change. The detection circuit 34 detects this change in the detection signal Sd. That is, the detection circuit 34 detects the detection target based on the change in the detection signal (details will be described later).

Next, the operation of the detection system 1 when the detection system 1 does not detect a detection target will be described with reference to FIGS. 6 and 7. Further, the detection target will be explained using the operator M's finger as an example. In other words, the case where the detection system 1 is not detecting the detection target is the case where the finger of the operator M is not close to the sensor 12.

FIG. 7 is a diagram showing a time chart of the operation of the detection system 1. In FIG. 7, the on/off state of each switch SW1, SW2, and SW3, the waveforms of the drive signal Sg and the anti-phase signal Sr, and the capacitance Ce of the electrode 14 when the detection system 1 is not detecting a detection target (hereinafter referred to as electrode capacitance Ce) are shown. The potential of the signal Sd and the waveform of the detection signal Sd are shown by thick solid lines, respectively.

The drive signal Sg and the anti-phase signal Sr are synchronized with each other as described above, and are each output at the second predetermined period T2. Before time t1 shown in FIG. 7, the potential of the drive signal Sg and the potential of the anti-phase signal Sr are the reference potential V0, the first switch SW1 is off, the second switch SW2 is on, and the second switch SW2 is on. The explanation will start from the state where the 3-switch SW3 is on. At this time, the detection signal generation circuit 33 has been reset, and the detection signal generation circuit 33 and the electrode 14 are connected. As a result, the potential of the electrode capacitor Ce and the potential of the detection signal Sd are equal to the reference potential V0.

From this state, at the timing when the potential of the drive signal Sg rises from the reference potential V0 to the drive potential Vg1 according to the drive voltage Vg, the detection circuit 34 turns on the first switch SW1, turns off the second switch SW2, and turns off the third switch. Switch SW3 off (time t1). As a result, when the electrode 14 and the detection signal generation circuit 33 are cut off and the first signal output circuit 31 and the electrode 14 are connected, the drive signal Sg is supplied to the electrode 14 and the electrode capacitance Ce is charged. Then, the potential of the electrode capacitor Ce becomes the first charging potential Ve1 corresponding to the drive potential Vg1.

Subsequently, the detection circuit 34 turns off the first switch SW1 (time t2). As a result, the first signal output circuit 31 and the electrode 14 are cut off, and the supply of the drive signal Sg to the electrode 14 is stopped. At this time, the electrode 14 is in a floating state, but the first charging potential Ve1 is maintained.

Further, the detection circuit 34 turns on the second switch SW2 (time t3). As a result, when the electrode 14 and the detection signal generation circuit 33 are connected, the electric charge of the electrode capacitance Ce moves to the capacitance of the capacitor Cd, so that the potential of the electrode capacitance Ce decreases and the capacitance of the capacitor Cd increases. The potential of the detection signal Sd increases accordingly. At this time, the potential of the detection signal Sd becomes the first detection potential Vd1 corresponding to the first charging potential Ve1 (time t4).

Subsequently, the detection circuit 34 turns on the third switch SW3 (time t4). As a result, when the detection signal generation circuit 33 is reset in a state where the detection signal generation circuit 33 and the electrode 14 are connected, the potential of the electrode capacitor Ce and the potential of the detection signal Sd each become equal to the reference potential V0. . Note that at this time, the potentials of the drive signal Sg and the anti-phase signal Sr have decreased and are equal to the reference potential V0.

In this way, the detection circuit 34 repeatedly controls the switches SW1, SW2, and SW3 in synchronization with the drive signal Sg. As a result, when the detection system 1 does not detect a detection target, the potential of the detection signal Sd repeatedly fluctuates between the reference potential V0 and the first detection potential Vd1 at the second predetermined period T2, as described above. .

Next, the operation of the detection system 1 when the detection system 1 detects a detection target will be described with reference to FIGS. 6 and 7. Furthermore, in order to clarify the features of the present disclosure, first, the operation of the detection system 1 in a state where the antiphase signal Sr is not output will be described.

Even when the antiphase signal Sr is not output, the drive signal Sg is output at the second predetermined period T2, and the detection circuit 34 switches the first switch SW1 and the first switch in synchronization with the drive signal Sg. The second switch SW2 and the third switch SW3 are controlled.

When the anti-phase signal Sr is not output, no induced voltage is generated in the operator M even if the operator M is located near the conductor 20. In this case, the potential of the operator M is approximately equal to the reference potential V0.

In this state, when the finger F of the operator M shown in FIG. 6 contacts the detection surface 12a of the sensor 12, the capacitance Cm of the operator M (hereinafter referred to as human body capacitance Cm) and the electrode capacitance Ce are combined.

In this specification, "contact" refers to a state in which the operator M is in contact with the detection surface 12a, or a state in which the operator M and the detection surface 12a are so close that it can be equated with the operator M touching the detection surface 12a. Refers to the state of being in close proximity. Further, the capacitance in which the human body capacitance Cm and the electrode capacitance Ce are combined is referred to as a coupling capacitance Cc. In FIG. 7, the potential of the coupling capacitance Cc when the antiphase signal Sr is not output is shown by a dashed line with the horizontal axis corresponding to the reference potential V0 shared with the electrode capacitance Ce, and the potential of the electrode capacitance Ce. The overlapping portion is shown with a solid line.

When the drive signal Sg is supplied to the electrode 14 while the finger F of the operator M is in contact with the detection surface 12a (time t1 to t2), the coupling capacitance Cc is charged. At this time, the second charging potential Ve2 of the charged coupling capacitance Cc is higher than the first charging potential Ve1 by the amount of the charged human body capacitance Cm (times t1 to t3). This charged human body capacitance Cm corresponds to the potential difference between the reference potential V0, which is the potential of the operator M, and the drive voltage Vg.

Furthermore, the potential of the detection signal Sd becomes the second detection potential Vd2 corresponding to the second charging potential Ve2 (time t4), as shown by the dashed line. The second detection potential Vd2 is larger than the first detection potential Vd1 when the detection system 1 does not detect a detection target by an amount corresponding to the potential difference between the first charging potential Ve1 and the second charging potential Ve2.

The detection circuit 34 detects the finger F of the operator M based on the potential difference between the first detection potential Vd1 and the second detection potential Vd2. For example, the detection circuit 34 detects the finger F of the operator M when the potential of the detection signal Sd becomes equal to or higher than the threshold value Vh. The threshold value Vh is a potential of the detection signal Sd between the first detection potential Vd1 and the second detection potential Vd2, is actually measured and derived through experiments or the like in advance, and is stored in the control device 30. That is, when the potential of the detection signal Sd changes from the first detection potential Vd1 to the second detection potential Vd2 which is greater than the threshold value Vh, the detection circuit 34 detects the finger F of the operator M. In this way, the detection circuit 34 detects a change in the detection signal, and detects a detection target based on the change in the detection signal.

Next, the operation of the detection system 1 when the detection system 1 detects a detection target in a state where the antiphase signal Sr is output will be described. At this time, as shown in FIG. 7, the drive signal Sg and the anti-phase signal Sr are synchronized with each other as described above, and are each output at the second predetermined period T2. Further, as described above, the detection circuit 34 controls the first switch SW1, the second switch SW2, and the third switch SW3 in synchronization with the drive signal Sg.

The operator M is located near the conductor 20 to which the anti-phase signal Sr is supplied, for example by sitting on the seat 2 of the vehicle. As a result, an induced voltage corresponding to the opposite phase voltage Vr is generated in the operator M. The phase of the induced voltage according to the anti-phase voltage Vr is in the same phase as the anti-phase voltage Vr, and is in anti-phase with the drive voltage Vg.

When an induced voltage is generated in the operator M, radio waves corresponding to the induced voltage are radiated from the operator M to the outside. As a result, when the finger F of the operator M approaches the sensor 12, the radio waves emitted from the finger F of the operator M reach the electrode 14 even if the finger F of the operator M is not in contact with the detection surface 12a. By doing so, the human body capacitance Cm and the electrode capacitance Ce are coupled. In FIG. 7, the potential of the coupling capacitance Cc when the anti-phase signal Sr is output is shown by a broken line with the horizontal axis corresponding to the reference potential V0 shared with the electrode capacitance Ce. Overlapping portions are indicated by solid lines.

When an induced voltage is generated in the operator M, the charged human body capacitance Cm is charged by the potential difference between the induced voltage and the drive voltage Vg. Since the induced voltage according to the anti-phase voltage Vr and the drive voltage Vg are in opposite phases, the potential difference between the induced voltage and the drive voltage Vg is larger than the potential difference between the reference potential V0 and the drive voltage Vg. Therefore, the charged human body capacitance Cm when an induced voltage corresponding to the opposite phase voltage Vr is generated in the operator M is driven by the reference potential V0 when an induced voltage is not generated in the operator M as described above. It is larger than the human body capacitance Cm charged by the potential difference of the voltage Vg.

Therefore, when an induced voltage corresponding to the opposite phase voltage Vr is generated in the operator M, the third charging potential Ve3 of the charged coupling capacitance Cc is the same as the induced voltage of the charged human body capacitance Cm, as shown by the broken line. is larger than the second charging potential Ve2 by the amount increased by (times t1 to t3).

Further, when an induced voltage corresponding to the opposite phase voltage Vr is generated in the operator M, the potential of the detection signal Sd becomes the third detection potential Vd3 corresponding to the third charging potential Ve3, as shown by the broken line ( Time t4). The third detection potential Vd3 is larger than the second detection potential Vd2 when no induced voltage is generated in the operator M by an amount corresponding to the potential difference between the second charging potential Ve2 and the third charging potential Ve3. When the potential of the detection signal Sd changes from the first detection potential Vd1 to the third detection potential Vd3, which is greater than the threshold value Vh, the detection circuit 34 detects the finger F of the operator M.

Further, the detection signal changes depending on the distance between the finger F of the operator M and the detection surface 12a. Specifically, the closer the distance between the finger F of the operator M and the detection surface 12a is, the greater the third detection potential Vd3 becomes. This is because the influence of the radio waves radiated from the finger F of the operator M on the drive signal Sg increases as it approaches the detection surface 12a, and the potential difference between the induced voltage and the drive voltage Vg increases. Therefore, by adjusting the threshold value Vh, the distance between the detection target and the detection surface 12a when the detection circuit 34 detects the detection target such as the finger F of the operator M can be adjusted.

In this way, even if the finger F of the operator M and the detection surface 12a do not make contact and are relatively far apart, the detection circuit 34 detects that the opposite phase signal Sr is generated in the operator by the conductor to which the opposite phase signal Sr is supplied. A change in the detection signal Sd according to the induced voltage can be detected, and thus the finger F of the operator M can be detected. In other words, by the second signal output circuit 32 outputting the opposite phase signal Sr to the conductor 20, the sensitivity of the detection system 1 to the detection target can be improved. Note that in the present disclosure, the ability to detect the position and motion of the finger F of the operator M in a state where the finger F of the operator M is not in contact with the detection surface 12a is referred to as hover detection.

Further, the potential difference of the detection signal Sd that occurs when the operator M performs the operation is the potential difference when the opposite phase signal Sr is not supplied to the conductor 20 (= second detection potential Vd2 - first detection potential Vd1) The potential difference (=third detection potential Vd3−first detection potential Vd1) when the opposite phase signal Sr is supplied to the conductor 20 is larger than that. That is, the second signal output circuit 32 outputs the opposite phase signal Sr to the conductor 20, and an induced voltage is generated in the operator M, thereby improving the sensitivity of the detection system 1 to the detection target such as the finger F of the operator M. do.

Further, the potential difference between the third detection potential Vd3 and the threshold value Vh is larger than the potential difference between the second detection potential Vd2 and the threshold value Vh. Therefore, the detection circuit 34 can easily detect a detection target such as the finger F of the operator M even when the operator M does not touch the sensor 12. Further, the detection circuit 34 can easily detect the detection target such as the finger F of the operator M even when the human body capacity Cm of the operator M is relatively small or when the human body capacity Cm of the operator M varies due to external factors. can be detected.

It should be noted that as the amplitude Hr of the anti-phase voltage Vr and thus the amplitude of the induced voltage increases with respect to the amplitude Hg of the drive voltage Vg, the third charging potential Ve3 and thus the third detection potential Vd3 increase, and the difference between the first detection potential Vd1 and the third detection potential Vd1 increases. The potential difference with the detection potential Vd3 becomes large. In other words, the greater the amplitude Hr of the anti-phase voltage Vr with respect to the amplitude Hg of the drive voltage Vg, the greater the sensitivity of the sensor 12 to a detection target such as the finger F of the operator M can be made. Note that the amplitude of the anti-phase voltage Vr may be smaller than the amplitude of the drive voltage Vg.

<Second embodiment>
Next, regarding the detection system 1 according to the second embodiment, mainly the differences from the detection system 1 according to the first embodiment described above will be explained.

In the detection system 1 of the second embodiment, the control device 30 selects an operation mode and controls the detection system 1. Specifically, the control device 30 controls the detection system 1 by selecting one of a detection mode in which the detection system 1 detects a detection target and a non-detection mode in which the detection system 1 does not detect a detection target. The control device 30 selects one of the detection mode and the non-detection mode, for example, when the operator M operates a switch (not shown) that the detection system 1 further includes.

When the control device 30 controls the detection system 1 in the detection mode, the second signal output circuit 32 outputs the opposite phase signal Sr to the conductor 20, similarly to the first embodiment described above. This improves the sensitivity of the detection system 1 to the detection target, as in the first embodiment, and the detection circuit 34 detects that the detection target, such as the finger F of the operator M, is relatively far from the detection surface 12a. Even in this case, the finger F of the operator M is detected (that is, hover detection).

Note that when the control device 30 controls the detection system 1 in the detection mode, the second signal output circuit 32 does not need to output the opposite phase signal Sr to the conductor 20. In this case, as described above, the detection circuit 34 detects the finger F of the operator M when the detection target such as the finger F of the operator M contacts the detection surface 12a. That is, in the detection mode, the operation of the operator M on the detection system 1 is permitted.

On the other hand, when the control device 30 controls the detection system 1 in the non-detection mode, the second signal output circuit 32 outputs the in-phase signal Ss generated by the in-phase voltage Vs to the conductor 20.

FIG. 8 is a diagram showing the waveform of the in-phase voltage. The phase of the in-phase voltage Vs is the same as that of the drive voltage Vg. The period of the in-phase voltage Vs is the same as the period of the drive voltage Vg, which is the first predetermined period T1. Further, the amplitude of the in-phase voltage Vs is equal to the amplitude Hs of the drive voltage Vg shown in FIG.

The in-phase signal Ss generated by the in-phase voltage Vs is an AC rectangular wave like the drive signal Sg and the anti-phase signal Sr. Further, the second signal output circuit 32 outputs an in-phase signal Ss to the conductor 20 in synchronization with the drive signal Sg. That is, the period of the in-phase signal Ss is the second predetermined period T2, which is equal to the drive signal Sg and the anti-phase signal Sr.

In this way, depending on the operation mode, the second signal output circuit 32 selects one of the in-phase signal Ss and the anti-phase signal Sr generated by the in-phase voltage Vs having the same phase as the drive voltage Vg. and output to the conductor 20.

Next, the operation of the detection system 1 when the control device 30 controls the detection system 1 in the non-detection mode will be described using FIG. 7. In FIG. 7, the waveform of the in-phase signal Ss matches the waveform of the anti-phase signal Sr, and is indicated by a solid line.

When operating the detection system 1, the operator M is located near the conductor 20 to which the in-phase signal Ss is supplied, and an induced voltage corresponding to the in-phase voltage Vs is generated in the operator M. The phase of the induced voltage according to the in-phase voltage Vs is in the same phase as the in-phase voltage Vs, and is in the same phase as the drive voltage Vg.

When an induced voltage is generated in the operator M, radio waves corresponding to the induced voltage are radiated from the operator M to the outside. As a result, when the finger F of the operator M approaches the detection surface 12a, the radio waves emitted from the operator M reach the electrode 14 even when the finger F of the operator M is not in contact with the sensor 12. , human body capacitance Cm and electrode capacitance Ce are coupled.

Further, when an induced voltage is generated in the operator M, the charged human body capacitance Cm is charged by the potential difference between the induced voltage and the drive voltage Vg. The induced voltage according to the in-phase voltage Vs and the driving voltage Vg are in the same phase with each other, and the amplitude Hs of the in-phase voltage Vs is equal to the amplitude of the driving voltage Vg, so the potential difference between this induced voltage and the driving voltage Vg is , is almost zero. In other words, when an induced voltage corresponding to the in-phase voltage Vs is generated in the operator M, the human body capacitance Cm is not charged and is approximately zero.

Therefore, when an induced voltage corresponding to the in-phase voltage Vs is generated in the operator M, only the electrode capacitance Ce is charged, so the potential of the charged coupling capacitance Cc is approximately equal to the first charging potential Ve1 ( time t1 to t3). Therefore, the potential of the detection signal Sd corresponding to the potential of the charged coupling capacitor Cc is approximately equal to the first detection potential Vd1 corresponding to the first charging potential Ve1 (time t4).

That is, when the in-phase signal Ss is supplied to the conductor 20, even if the operator M operates the detection system 1, the potential of the detection signal Sd hardly changes and does not exceed the threshold value Vh. Therefore, the detection circuit 34 does not detect the finger F of the operator M. That is, in the non-detection mode, the second signal output circuit 32 outputs the in-phase signal Ss, thereby inhibiting the operator M from operating the detection system 1.

<Third embodiment>
Next, regarding the detection system 1 according to the third embodiment, mainly the differences from the detection system 1 according to the second embodiment described above will be explained.

FIG. 9 is a diagram showing the configuration of a detection system 1 according to the third embodiment. The detection system 1 of the third embodiment includes two conductors 120. Specifically, the detection system 1 includes a first conductor 121 and a second conductor 122.

The first conductor 121 and the second conductor 122 are arranged such that a plurality of different operators M are located therein. For example, the first conductor 121 is placed in the driver's seat 3 of a vehicle, and the second conductor 122 is placed in the passenger seat 4 of the vehicle.

In the third embodiment, the control device 30 controls the detection system 1 by selecting an operation mode for each of the driver's seat 3 and the passenger seat 4. The second signal output circuit 32 selects and outputs one of the anti-phase signal Sr and the same-phase signal Ss to the first conductor 121 and the second conductor 122, respectively, depending on the operation mode.

When the detection mode is selected for the driver's seat 3, the second signal output circuit 32 outputs the opposite phase signal Sr to the first conductor 121. In this case, the detection circuit 34 detects the finger F of the operator M located in the driver's seat 3 as described above. Therefore, the operator M located in the driver's seat 3 is allowed to operate the detection system 1.

On the other hand, when the non-detection mode is selected for the driver's seat 3, the second signal output circuit 32 outputs the same phase signal Ss to the first conductor 121. In this case, the detection circuit 34 does not detect the finger F of the operator M located in the driver's seat 3 as described above. Therefore, the operator M located in the driver's seat 3 is prohibited from operating the detection system 1.

Further, when the detection mode is selected for the passenger seat 4, the second signal output circuit 32 outputs the opposite phase signal Sr to the second conductor 122. In this case, the detection circuit 34 detects the finger F of the operator M located on the passenger seat 4 as described above. Therefore, the operator M located in the passenger seat 4 is allowed to operate the detection system 1.

On the other hand, when the non-detection mode is selected for the passenger seat 4, the second signal output circuit 32 outputs the same phase signal Ss to the second conductor 122. In this case, the detection circuit 34 does not detect the finger F of the operator M located on the passenger seat 4 as described above. Therefore, the operator M located in the passenger seat 4 is prohibited from operating the detection system 1.

In this way, one of the anti-phase signal Sr and the same-phase signal Ss is selectively supplied to the first conductor 121 and the second conductor 122, so that the operator M corresponding to the first conductor 121 The operator M corresponding to the second conductor 122 can be permitted or prohibited from operating the detection system 1 .

For example, when allowing an operation by the operator M located in the driver's seat 3 and prohibiting an operation by the operator M located in the passenger seat 4, the second signal output circuit 32 sends an opposite phase signal to the first conductor 121. Sr, and outputs an in-phase signal Ss to the second conductor 122.

Note that although the detection system 1 has two conductors 120, it goes without saying that the number of conductors 120 is not limited to this. For example, the detection system 1 may include three electrical conductors 120, and the three electrical conductors 120 may be arranged at the driver's seat 3, passenger seat 4, and rear seat of the vehicle, respectively. Further, the conductor 120 may be placed on a seat or other object located near an operator in a vehicle other than a vehicle, a public facility, an entertainment facility, or the like.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various changes can be made without departing from the spirit of the present invention. Appropriate changes made within the scope of the invention also fall within the technical scope of the invention.

For example, the sensor 12 described above is a self-capacitance type sensor, but a surface-type capacitance type sensor in which a plurality of (for example, four) electrodes are arranged on the periphery of the sensor substrate 13, and For example, other capacitance type sensors such as a projected capacitance type sensor in which the sensors are arranged in a grid pattern in a plan view may be used.

Furthermore, the amplitude Hs of the in-phase voltage Vs may be different from the amplitude Hg of the drive voltage Vg. In this case, the smaller the difference between the amplitude Hs of the in-phase voltage Vs and the amplitude Hg of the drive voltage Vg, the smaller the fluctuation in the potential of the detection signal Sd caused by the approach of the finger F of the operator M. Therefore, the smaller the difference between the amplitude Hs of the in-phase voltage Vs and the amplitude Hg of the drive voltage Vg, the easier it is to prevent the detection system 1 from detecting a detection target such as the finger F of the operator M.

Further, when the operator M is located near the conductors 20, 120, the second signal output circuit 32 outputs one of the anti-phase signal Sr and the same-phase signal Ss, When person M is not located, it is not necessary to output one of the anti-phase signal Sr and the same-phase signal Ss. In this case, the detection system 1 further includes a detection sensor that detects the operator M, and when the operator M is detected by this detection sensor, the second signal output circuit 32 outputs an anti-phase signal Sr and an in-phase signal Ss. Output one of the two. This detection sensor is, for example, a switch activated by the weight of the operator M, a load sensor that detects the weight of the operator M, and a distance sensor that detects the distance to the operator M.

In addition, other effects brought about by the aspects described in this embodiment that are obvious from the description in this specification or that can be appropriately conceived by those skilled in the art are naturally understood to be brought about by the present disclosure. .

1 detection system 12 sensor 12a detection surface 20, 120 conductor 30 control device 31 first signal output circuit 32 second signal output circuit 33 detection signal generation circuit 34 detection circuit Hg amplitude Hr amplitude Hs amplitude M operator Sd detection signal Sg drive Signal Sr Anti-phase signal Ss In-phase signal T1 First predetermined period (predetermined period)
Vg Drive voltage Vr Anti-phase voltage Vs In-phase voltage

Claims (5)

A capacitive sensor with multiple electrodes,
a conductor;
a first signal output circuit that outputs a drive signal generated by a drive voltage that varies at a predetermined cycle to the plurality of electrodes;
a second signal output circuit that outputs an anti-phase signal generated by an anti-phase voltage that is anti-phase to the phase of the drive voltage to the conductor;
a detection signal generation circuit that generates a detection signal according to the capacitance of the electrode;
a detection circuit that detects a change in the detection signal according to an induced voltage generated in the operator by the conductor to which the opposite phase signal is supplied;
detection system. The amplitude of the anti-phase voltage is greater than or equal to the amplitude of the drive voltage,
Detection system according to claim 1. The sensor further includes a detection surface,
The detection signal changes depending on the distance between the detection surface and the operator.
Detection system according to claim 1. The second signal output circuit selects one of an in-phase signal generated by an in-phase voltage having the same phase as the drive voltage and the anti-phase signal, and outputs the selected one to the conductor.
Detection system according to claim 1. comprising two of the conductors,
The second signal output circuit is
outputting the opposite phase signal to one of the conductors;
outputting an in-phase signal generated by an in-phase voltage having the same phase as the drive voltage to the other conductor;
Detection system according to claim 1.

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