WO2016147423A1 - Capacitive touch panel - Google Patents
Capacitive touch panel Download PDFInfo
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- WO2016147423A1 WO2016147423A1 PCT/JP2015/067374 JP2015067374W WO2016147423A1 WO 2016147423 A1 WO2016147423 A1 WO 2016147423A1 JP 2015067374 W JP2015067374 W JP 2015067374W WO 2016147423 A1 WO2016147423 A1 WO 2016147423A1
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- input operation
- detection
- circuit
- detected
- electrode
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
- G06F3/0446—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
Definitions
- the present invention relates to a capacitive touch panel that detects an input operation position from an arrangement position of a detection electrode on an input operation surface, in which the capacitance with the input operation body changes as the input operation body approaches. Relates to a capacitive touch panel that accurately detects each input operation position even when there is a so-called multi-touch operation in which a plurality of positions on the input operation surface are input simultaneously.
- Patent Document 1 As the detection method of the input operation position of the capacitive touch panel, for example, as shown in JP 2013-534343 A (Patent Document 1), a detection electrode in which stray capacitance increases as the input operation body approaches The self-capacitance method (one-wire method) that detects the input operation position from the center of gravity for comparing the amount of change in stray capacitance for a plurality of detection electrodes, and Japanese Patent Publication No. 2012-502397 (Patent Document 2) As described above, an AC detection signal of a predetermined voltage level is applied to the drive electrode, and the input operation position is detected from the intersection position of the detection electrode where the reception level of the AC detection signal is lowered when the drive electrode approaches the input operation body.
- Patent Document 2 As described above, an AC detection signal of a predetermined voltage level is applied to the drive electrode, and the input operation position is detected from the intersection position of the detection electrode where the reception level of the AC detection signal is lowered when the drive electrode approaches the input operation body.
- the mutual capacity method two-wire type
- the self-capacitance method only the plurality of detection electrodes insulated from each other are wired in the first direction and the second direction along the input operation surface, and the drive electrode is not wired, so that the structure is simplified. If the number of detection electrode wirings is scanned, the input operation positions in the first direction and the second direction can be detected, so that there is an advantage in that the scan time is short and the power consumption is small.
- a multi-touch operation in which it is difficult to narrow down the position to one place and two or more positions on the input operation surface are input simultaneously, in addition to the actual input operation position, different positions in the first direction and the second direction are set.
- the plurality of first detection electrodes wired in the first direction and the second detection electrodes wired in the second direction are insulated from each other and wired along the input operation surface of the insulating panel. Scanning with one drive electrode for applying an AC detection signal and the other electrode for detecting the reception level of the AC detection signal for all the intersection positions of the drive electrode and the detection electrode, and the detection electrode and drive with a lowered reception level Input operation positions in the first direction and the second direction are detected from the intersection positions of the electrodes.
- 101 is a transmission circuit for transmitting an AC detection signal
- 102 is a voltmeter
- 103 is a drive arranged on the input operation surface.
- 104 is a reception electrode serving as a detection electrode arranged in the vicinity of the transmission electrode 103 on the input operation surface
- 107 is a forward direction from the transmission circuit 101 to the transmission electrode 103.
- a diode 108 is connected to a grounding capacitor for detecting the potential of the receiving electrode 104 by a mutual capacitance method.
- a switch 105 between the transmission electrode 103 and the reception circuit 102 is provided as shown in FIG. ON, the switch 106 between the receiving electrode 104 and the receiving circuit 102 is turned OFF.
- the self-capacitance (capacitance) 120 therebetween is charged by the AC detection signal.
- the potential of the transmission electrode 103 gradually rises as this capacitance is charged, and the switch 105 is turned on and the reception circuit 102 connected to the transmission electrode 103 has the potential of the rising transmission electrode 103 kept constant.
- the capacitance 120 between the transmission electrode 103 and the detected object 110 is inversely proportional to the distance between them, the capacitance increases as the detected object 110 approaches the transmission electrode 103, and the capacitance 120 is charged by the AC detection signal. As a result, the rising speed of the potential of the transmitting electrode 103 is also slowed down, and the elapsed time detected by the receiving circuit 102 is lengthened. Therefore, the capacitance sensor 100 detects that the detection object 110 has approached the transmission electrode 103 because the elapsed time detected by the reception circuit 102 becomes long.
- a switch between the transmission electrode 103 and the reception circuit 102 as shown in FIG. 105 is turned off, and the switch 106 between the receiving electrode 104 and the receiving circuit 102 is turned on.
- an AC detection signal is transmitted from the transmission circuit 101 to the transmission electrode 103, a combined capacitance composed of the mutual capacitance (capacitance) 130 and the ground capacitance 108 between the transmission electrode 103 and the reception electrode 104 connected in series is charged.
- the potential on the high voltage side of the receiving electrode 104 or the grounding capacitor 108 gradually rises due to charging, and the receiving circuit 102 connected to the high voltage side of the grounding capacitor 108 detects the elapsed time until this rising potential reaches a certain potential. .
- the combined capacitance of the mutual capacitance (capacitance) 130 and the ground capacitance 108 to which the current due to the AC detection signal is connected in series is set.
- the object to be detected 110 approaches between the electrodes 103 and 104, a part of the current flows from the transmission electrode 103 to the object to be detected 110, and the mutual capacitance (capacitance) 130 decreases.
- the combined capacity is also reduced, the charging speed is increased, and the elapsed time detected by the receiving circuit 102 is shortened. Accordingly, since the elapsed time detected by the reception circuit 102 is shortened, the capacitance sensor 100 detects that the detection object 110 has approached the transmission electrode 103 and the reception electrode 104, and the transmission electrode 103 and the reception electrode. The position of the detected object 110 is detected from the arrangement position 104. This self-capacitance method of the capacitance sensor 100 can detect the approached state before the detection object 110 reaches the transmission electrode 103 on the input operation surface, but the elapsed time detected by the reception circuit 102 becomes longer. Since the approach of the detection object 110 is detected, the detection time is long.
- the mutual capacitance method cannot detect the detected object 110 until the detected object 110 approaches between the transmitting electrode 103 and the receiving electrode 104, but the elapsed time detected by the receiving circuit 102 is shortened. Since the approach of 110 is detected, the detection object 110 that has a short detection time and moves at high speed can be detected. Therefore, the capacitance sensor 100 switches between the self-capacitance method and the mutual capacitance method, and normally detects the approach of the detected object 110 by the self-capacitance method, and after the approach of the detected object 110 is detected. The movement of the detection object that moves at high speed is detected by switching to the operation of the mutual capacitance method.
- the above-mentioned “ghost generation” problem occurs.
- the input operation position actually multi-touched is determined from the change in capacitance of each auxiliary detection electrode. Yes.
- a plurality of auxiliary detection electrodes in different directions must be wired so that all the detection electrodes are insulated from each other. It is not practical because it is complicated. If the input operation position is detected by the mutual capacitance method, there is no problem of ghost generation, and each input operation position by the multi-touch operation can be detected.
- Patent Document 3 switches between the self-capacitance method and the mutual capacitance method according to the detection application.
- a capacitive touch panel that switches from the self-capacitance method to the mutual capacitance method only when a multi-touch operation is detected has been studied.
- Patent Document 1 and Patent Document 3 when the input operation position of the input operation body is detected by the conventional self-capacitance method, between the input operation body and the detection electrode to which the AC detection signal is applied.
- the distance between the detection electrode and the input operation body is obtained from the elapsed time until reaching a predetermined charging potential that changes according to the amount of change in the capacitance of the input, the distance between the input operation body and the detection operation electrode Although it is inversely proportional to the capacitance between the body and the detection electrode, there is no linearity with the elapsed time that is actually detected, and the distance between the detection electrode and the input operation body cannot be detected with high accuracy from the elapsed time.
- the input operation object is determined from the center of gravity of the amount of change in capacitance for each detection electrode wired in two directions.
- the input operation position in two directions is detected, and since there is no linearity and distance from the input operation body in the elapsed time representing the amount of change in capacitance for each detection electrode, the input operation position obtained from its center of gravity The accuracy of. Therefore, even if the self-capacitance method is switched to the mutual capacitance method only when a multi-touch operation is detected, the self-capacitance method cannot be adopted for detecting a normal input operation position that does not detect the multi-touch operation. Furthermore, since the self-capacitance type capacitive touch panel has poor detection accuracy of the input operation position as described above, it is difficult to detect the multi-touch operation itself. If it is not close enough to touch the touch panel, two or more independent input operation positions cannot be detected.
- the present invention has been made in consideration of such conventional problems, and provides a capacitive touch panel that detects an input operation position of a normal input operation that is not a multi-touch operation at high speed and with high accuracy. For the purpose. It is another object of the present invention to provide a capacitive touch panel that switches to a mutual capacitance method that does not cause a ghost problem before the input operation body touches the input operation surface when a multi-touch operation is detected.
- the capacitive touch panel according to claim 1 includes a plurality of first detection electrodes wired in a first direction along the input operation surface of the insulating substrate, and a first along the input operation surface.
- First transmission means for transmitting, and first signal detection means for detecting the reception level of the first AC detection signal appearing on each detection electrode via the capacitance between each detection electrode and the input operation body, Based on the reception level of the first AC detection signal detected for each detection electrode, the distance between the detection electrode and the input operation body is obtained, and the distance between each detection electrode and the input operation body is compared.
- a first detection circuit for detecting an input operation position, and a plurality of first detection electrodes in order
- a second transmission means for transmitting a flow detection signal, and a plurality of second intersecting with the first detection electrode for transmitting the second AC detection signal via a capacitance between the first detection electrode and the second detection electrode.
- a second signal detecting means for detecting a reception level of the second AC detection signal appearing on the detection electrode, the first detection electrode on which the input operation body approaches and the reception level changes and the second detection electrode on the insulating substrate
- a second detection circuit that detects the input operation position of the input operation body on the input operation surface from the intersection position, and a multi-touch operation is determined when the first detection circuit detects an input operation position by two or more input operation bodies
- a switching control circuit for switching to one of the first detection circuit and the second detection circuit according to the determination result of the determination means, and the first detection is performed when the determination means does not determine the multi-touch operation.
- the second detection circuit When the input operation position of the input operation body on the screen is detected and the determination means determines that the operation is a multi-touch operation, the second detection circuit is operated to input the input operation positions of two or more input operation bodies on the input operation surface. Are detected respectively.
- the capacitance between the detection electrode and the input operation body is Cm
- the distance between the detection electrode and the input operation body is d
- the output level of the first AC detection signal is Vs
- k is a constant.
- the first detection circuit performs the input operation with the first detection electrode in the direction orthogonal to the first direction from the reception level Vi of the first AC detection signal detected by the first detection electrode wired along the first direction.
- the distance between the bodies is between the second detection electrode and the input operation body in the direction orthogonal to the second direction from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction.
- the second detection circuit includes a first detection electrode that applies the second AC detection signal and a second detection electrode that detects the reception level of the second AC detection signal.
- each input operation position can be determined without causing a ghost even if there is a multi-touch operation. It can be detected accurately. Since the first detection circuit and the second detection circuit share the plurality of first detection electrodes and the plurality of second detection electrodes, the input operation position can be detected by different detection methods without significantly changing the structure.
- the determination unit detects an input operation position by two or more input operation bodies before the first detection circuit detects an input operation position of the input operation body on the input operation surface. In this case, it is determined that the operation is a multi-touch operation.
- the determination means can determine that the input operation surface is a multi-touch operation even if a plurality of input operation bodies are separated from the input operation surface.
- the second detection circuit can be activated to detect each input operation position of the multi-touch operation at high speed.
- the switching control circuit determines that the multi-touch operation is determined by the determination unit, the operation is switched from the first detection circuit to the second detection circuit, and the second detection circuit performs the input operation.
- the operation is switched from the second detection circuit to the first detection circuit.
- the second detection circuit operates to detect the input operation position, and when the multi-touch operation input operation ends, the first detection circuit operates. Therefore, the first detection circuit operates in the standby state of the input operation.
- the first detection circuit further includes a primary DC power supply circuit that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line, one of which is grounded or at a constant potential.
- a secondary DC power supply circuit that outputs a DC voltage from between the low-voltage vibration power supply line and the high-voltage vibration power supply line; and a high impedance for the first AC detection signal that is connected between the low-voltage reference power supply line and the low-voltage vibration power supply line.
- a first inductor that is connected between the high-voltage reference power supply line and the high-voltage vibration power supply line and that has a high impedance with respect to the first AC detection signal; And a first capacitor and a second capacitor connected between the high-voltage reference power supply line and the low-voltage reference power supply line, respectively, while the first detection circuit is operated, the operation of the second transmission means is stopped and the first transmission is performed.
- the first AC detection signal is output to the primary DC power supply circuit, and each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit.
- the second AC detection signal is sequentially output from the second transmission means to the plurality of first detection electrodes while the second detection circuit is operated by connecting to the first AC detection signal and vibrating at the frequency of the first AC detection signal.
- the output impedance viewed from the first capacitor and the second capacitor of the first transmission means is set to a low impedance, and the output of the first AC detection signal of the first transmission means is stopped.
- the primary DC power supply circuit While operating the first detection circuit, the primary DC power supply circuit operates with the secondary DC power supply circuit because one of the low-voltage reference power supply line and the high-voltage reference power supply line is connected to the ground or a constant potential and has a constant potential.
- the secondary DC power supply circuit When the first AC detection signal is output from the first transmitting means to the primary DC power supply circuit via the first capacitor and the second capacitor, the secondary DC power supply circuit relatively fluctuates at the frequency f of the first AC detection signal. . Since each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit, the potential relative to the constant potential input operation body at the frequency f of the first AC detection signal is relatively high. Fluctuate.
- a low-pass filter is formed between the primary DC power supply circuit and the secondary DC power supply circuit from the first inductor and the first capacitor or the second inductor and the second capacitor.
- the high frequency noise of the power supply circuit does not flow to each circuit connected to the secondary DC power supply circuit, and the high frequency noise generated in each circuit connected to the secondary DC power supply circuit does not flow to the primary DC power supply circuit side.
- a first AC detection signal whose relative potential with the input operation body varies is transmitted to each detection electrode of the plurality of second detection electrodes to be wired, and through the capacitance between each detection electrode and the input operation body, Detecting the reception level of the first AC detection signal appearing on each detection electrode, and determining the distance between the detection electrode and the input operating body based on the reception level of the first AC detection signal detected for each detection electrode;
- the input operation position of the input operation body is detected by comparing the distance between each detection electrode and the input operation body, and the input operation position by a single input operation body is detected until the detected input operation position reaches the input operation surface.
- the input of the input operation body on the input operation surface When the operation position is detected and the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the transmission of the first AC detection signal is stopped and a plurality of input operation positions are stopped.
- a second AC detection signal is sequentially transmitted to the first detection electrode, and a plurality of crossing the first detection electrode that transmits the second AC detection signal via the capacitance between the first detection electrode and the second detection electrode.
- the reception level of the second AC detection signal appearing on each second detection electrode is detected, and the input operation is performed from the crossing position on the insulating substrate of the first detection electrode and the second detection electrode where the input operation body approaches and the reception level changes.
- the input operation position of the input operation body on the surface is detected.
- the capacitance between the detection electrode and the input operation body is Cm
- the distance between the detection electrode and the input operation body is d
- the output level of the first AC detection signal is Vs
- k is a constant.
- the distance between the first detection electrode and the input operation body in the direction orthogonal to the first direction is The distance between the second detection electrode and the input operation body in the direction orthogonal to the second direction is obtained from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction.
- the two-dimensional input operation position along the input operation surface can be detected. If the input operation position is a single input operation body until the detected input operation position reaches the input operation surface, the input operation position is detected from the reception level Vi of the first AC detection signal by the same method.
- the input operation position of the input operation body can be accurately detected from the reception level Vi, and the first detection A two-dimensional input operation position on the input operation surface can be detected by simply detecting the reception level Vi for the total number of electrodes and the second detection electrodes.
- the first detection electrode and the second detection electrode are changed at each intersection position on the insulating substrate.
- each input operation position can be accurately detected. Even if multiple input operation bodies are separated from the input operation surface, it can be determined as a multi-touch operation, and before touching the input operation surface, switching to a different input operation position detection method can be performed at high speed. Each input operation position can be detected.
- the input operation position of normal input operation which is not multi-touch operation can be detected at high speed and with high precision.
- the second detection circuit is operated to detect the input operation position using a mutual capacitance method that does not cause ghosting. Can be detected.
- the first detection circuit and the first detection circuit can be used without significantly changing the structure. It can be set as the electrostatic capacitance type touch panel which switches operation
- the second aspect of the present invention it is possible to detect the multi-touch operation before the input operation body touches the input operation surface, and to switch to the mutual capacitance method that does not cause a ghost problem.
- the second detection circuit since the second detection circuit operates to detect the input operation position, each input operation position is detected without the problem of ghosting.
- the first detection circuit operates, so that the input operation position of the hover operation where the input operation body is separated from the input operation surface can be detected.
- the first transmission means is not provided on the input operation body side, and the first detection electrode for detecting the reception level is provided for each detection electrode.
- the two-dimensional input operation position can be detected only by scanning for detecting the reception level of each detection electrode, the detection cycle can be further shortened.
- the primary DC power supply circuit and the second capacitor are operated by using the first inductor and the first capacitor or the second inductor and the second capacitor that operate the first detection circuit to change the potential of each detection electrode and the input operation body.
- a low-pass filter that cuts off high-frequency noise between the secondary DC power supply circuits can be formed.
- the input operation position of the input operation by the single input operation body that is not the multi-touch operation can be detected at high speed and with high accuracy.
- the reception level is detected for each crossing position of the detection electrodes, so that it is possible to accurately detect each input operation position of the multi-touch operation without causing a ghost problem.
- FIG. 1 is a block diagram showing a capacitive touch panel 1 according to an embodiment of the present invention.
- FIG. 2 is a block diagram illustrating a configuration of a main part of the capacitive touch panel 1.
- FIG. 3 is an equivalent circuit diagram of the reference power supply circuit 4 and the vibration power supply circuit 3 when the first AC detection signal SG is output.
- FIG. 4 is an equivalent circuit diagram showing the relationship between the output level Vs of the first AC detection signal SG and the reception level Vi appearing on the detection electrode 10.
- FIG. 5 is a flowchart illustrating a process of detecting an input operation position of the capacitive touch panel 1.
- FIG. 6 is a block diagram for explaining the operation of the conventional capacitive touch panel 100 in the self-capacitance method.
- FIG. 7 is a block diagram for explaining the operation of the conventional capacitive touch panel 100 in the mutual capacitance method.
- main circuit components constituting the touch panel 1 include a DC power supply 16 that applies a DC voltage Vcc to a reference power supply circuit 4 including a low-voltage reference power supply line GND and a high-voltage reference power supply line VCC that are ground potentials; Non-vibration circuit components composed of other circuit components such as capacitors 17 and 18 connected to the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC, and the vibration side circuit indicated by the broken line in FIG. It is divided into vibration circuit components mounted on the substrate 2.
- the vibration side circuit board 2 is provided with a vibration power supply circuit 3 including a low-voltage vibration power supply line SGND and a high-voltage vibration power supply line SVCC.
- the low-voltage vibration power supply line SGND is connected to the low-voltage reference power supply line GND
- the high-voltage vibration power supply line SVCC is connected to the high-voltage reference power supply line VCC via the coils 5 and 6, respectively.
- the inductances of the coil 5 and the coil 6 are both set to a value that becomes high impedance with respect to a first AC detection signal SG having a natural frequency f described later.
- the coils 5 and 6 having the same inductance L are used. Yes. As a result, as shown in FIG.
- the reference power supply circuit 4 Since the low-voltage reference power line GND is grounded and has a stable potential, the potentials of the low-voltage vibration power line SGND and the high-voltage vibration power line SVCC of the vibration power circuit 3 fluctuate synchronously with the natural frequency f, and the voltage between them Vibrates while maintaining the same DC output voltage Vcc as the reference power supply circuit 4. As shown in FIG.
- the vibration circuit board 2 to which the vibration power supply circuit 3 is wired has a large number of X detection electrodes 10X (10) wired in the Y direction and a large number of Y detection electrodes wired in the X direction.
- 10Y (10) is connected to one of the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 3 via the diode 7, here the low-voltage vibration power supply line SGND.
- a large number of X detection electrodes 10X and Y detection electrodes 10Y are arranged so as to be insulated from each other along a surface serving as an input operation surface of the vibration side circuit board 2 or an insulating panel provided separately, and an operator is a finger 20 as an input operation body.
- the vibration side circuit board 2 further includes an X side analog multiplexer XMUX for switching the connection of the X detection electrode 10X, a Y side analog multiplexer YMUX for switching the connection of the Y detection electrode 10Y, and an output side of the multiplexer MUX via the amplifier circuit 8.
- the A / D converter ADC to be connected, the transmission circuit 11 for transmitting the first AC detection signal SG as shown in FIG. 1, the switching control circuit 12 for switching control of the connection of the analog multiplexer, and the second AC detection signal to the X detection electrode 10X.
- a CPU 9 including an electrode drive circuit 13 for transmitting SG ′, a coordinate calculation circuit 14, an interface circuit 15 and the like is mounted, all of which are connected to the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 3, It operates by receiving the output voltage Vcc from the power supply 16.
- the output side of the transmission circuit 11 is bifurcated and connected to the low-voltage reference power line GND and the high-voltage reference power line VCC via capacitors 17 and 18 respectively.
- Touch panel 1 includes any one of a first detection circuit that transmits first AC detection signal SG from transmission circuit 11 and a second detection circuit that transmits second AC detection signal SG ′ from electrode drive circuit 13. Are selectively operated, and the input operation position of the input operation body 20 is detected.
- the low-voltage reference power line GND of the reference power circuit 4 is connected to the first AC detection signal SG from the oscillation circuit 11 on the vibration power circuit 3 side via the capacitors 17 and 18 that bifurcate. Output to the high-voltage reference power line VCC.
- the natural oscillation signal SG having the natural frequency f flows in the reference power supply circuit 4 and the vibration power supply circuit 7
- the low voltage reference power supply line GND and the high voltage reference power supply line VCC and the low voltage vibration power supply line SGND and the high voltage vibration power supply line SVCC are close to each other.
- the reference power supply circuit 4 and the vibration power supply circuit 3 of FIG. 1 are shown in the equivalent circuit diagram of FIG.
- the combined capacitance is 2C.
- the combined inductance of the coils 5 and 6 connected in parallel between the reference power supply circuit 4 and the vibration power supply circuit 3 is L / 2.
- the resonance frequency f 0 obtained from the relationship of the expression (2) is the natural frequency f of the first AC detection signal SG
- the theory from the expression (1) is obtained with respect to the output level Vs of the first AC detection signal SG.
- the potential of the upper vibration power supply circuit 3 vibrates at infinity, and the potential of the detection electrode 10 connected to the vibration power supply circuit 3 can also be vibrated to infinity.
- the capacitance between the detection electrode 10 and the finger 20 is as small as about 10 pF, the voltage generated between the detection electrode 10 and the finger 20 expands infinitely.
- the reception level Vi of the first AC detection signal SG input to the arithmetic circuit 14 increases, and the detection becomes easy.
- the actual touch panel 1 does not resonate at the frequency f 0 obtained from the equation (2) due to the influence of the inductance and stray capacitance of the reference power supply circuit 4 and the vibration power supply circuit 3, and the reference power supply circuit 4 and the vibration power supply circuit 3 Due to an energy loss or the like when the first AC detection signal SG flows, the vibration power supply circuit 3 vibrates with an amplitude expanded to a finite magnification with respect to the output level Vs of the first AC detection signal SG.
- the natural frequency f of the first AC detection signal SG is shifted around the resonance frequency f 0 or the first AC detection is performed.
- the amplitude of the voltage oscillation of the detection electrode 10 is limited within a range in which the input operation can be reliably detected by the coordinate calculation circuit 14 of the CPU 9.
- the potential vibrates at the natural frequency f, while the potential of the operator's finger (input operation body) 20 whose part such as a foot is grounded. Is a constant potential, in the detection electrode 10 where the finger 20 approaches and the electrostatic capacitance Cf with the finger 20 increases, a voltage signal of the natural frequency f is transmitted from the detection electrode 10 to the finger 20 via the electrostatic capacitance Cf. Is output.
- the input operation causes the potential of the detection electrode 10 that the finger 20 has approached to vibrate relatively at the natural frequency f, and is driven by the vibration power supply circuit 3.
- the CPU 9 can detect the potential fluctuation signal of the natural frequency f, that is, the first AC detection signal, and can detect the input operation from the reception level Vi of the first AC detection signal detected by the detection electrode 10 that the finger 20 approaches.
- the electrostatic capacitance Cm between each detection electrode 10 and the input operation body 20 is the distance between the detection electrode and the input operation body d, the dielectric constant of vacuum ⁇ 0, the relative dielectric constant ⁇ of air is about 1, and the input operation body 20
- FIG. 4 is an equivalent circuit diagram of the first detection circuit showing the relationship between the potential Vs between the input operating body 20 and the detection electrode 10 and the reception level Vi of the AC detection signal SG appearing on the detection electrode 10.
- the output level of the AC detection signal SG that is, the potential between the detection electrode 10 and the input operating body 20
- Cp is the stray capacitance between the detection electrode 10 and the low-voltage vibration power supply line SGND
- rp is the internal resistance value of the detection electrode
- R4 is the resistance value of the output resistance.
- the expression (10) cannot be applied and the reception level Vi. Becomes a maximum output level Vs. If Expression (10) is used, the distance d between each detection electrode 10 and the finger 20 can be directly obtained from the reception level Vi of the first AC detection signal appearing on each of the plurality of detection electrodes 10, and this embodiment Then, the input in the XY directions parallel to the input operation surface is determined from the arrangement positions of all the detection electrodes 10 (X detection electrode 10X, Y detection electrode 10Y) switched by the multiplexer MUX and the reception level Vi detected from each detection electrode 10.
- a three-dimensional input operation position of the operation position (x, y) and the input operation position z in the Z direction orthogonal to the input operation surface is detected.
- the switching control circuit 12 of the CPU 9 switches and controls the X-side analog multiplexer XMUX and the Y-side analog multiplexer YMUX, and all the X detection electrodes in one scanning cycle.
- the 10X and Y detection electrodes 10Y are connected to the amplification circuit 8 composed of an operational amplifier for integration for each detection electrode 10 in order.
- the reception level Vi of the first AC detection signal appearing on all the detection electrodes 10 is amplified by the amplifier circuit 8 and then input to the A / D converter ADC.
- the A / D converter ADC samples at a frequency at least twice the natural frequency f of the first AC detection signal SG, quantizes the reception level Vi of the first AC detection signal SG, and outputs it to the coordinate calculation circuit 14 of the CPU 9. To do. Since the quantized data output from the A / D converter 14 represents the reception level Vi of the first AC detection signal SG appearing at the detection electrode 10 that is selectively connected by the analog multiplexer MUX at that time, the coordinate calculation for detecting the input operation position In the circuit 14, the total sum of the quantized data input from the A / D converter ADC during the connection period in which the detection electrode 10 is connected to the amplifier circuit 8 is compared with a predetermined threshold, and input when it is equal to or higher than the predetermined threshold.
- the distance d between the arrangement position of the detection electrode 10 and the input operation body 20 can be obtained from the equation (10).
- a three-dimensional input operation position including the height in the Z direction is detected.
- the transmission of the AC detection signal SG is stopped, and the operation is switched from the first detection circuit to the second detection circuit that detects the input operation position by the mutual capacitance method.
- the input operation is performed by the single input operation body 20, and the two-dimensional or three-dimensional input operation position detected by the coordinate calculation circuit 14 is supplied from the interface circuit 15 as a direct current.
- the signal is output to a host device that uses the input operation position by USB communication, I 2 C communication, or the like via the insulated signal line 19.
- the distance d between any one of the detection electrodes 10 and the input operating body 20 is proportional to the inverse of the reception level Vi of the first AC detection signal SG detected by the detection electrode 10 ((10)). Therefore, the three-dimensional input operation position including the height in the Z direction on the input operation surface is accurately determined from the reception level Vi detected by the X detection electrode 10X and the Y detection electrode 10Y that are arranged to intersect each other in the XY direction. It can be detected. Further, only by detecting the reception level Vi of each detection electrode 10 by scanning corresponding to the number of wirings of the detection electrodes 10 (X detection electrode 10X and Y detection electrode 10Y) in one scanning cycle, two-dimensional on the input operation surface.
- the input operation position can be detected at high speed and with low power consumption as compared with the mutual capacitance method in which all the intersections of the detection electrodes are scanned.
- the transmission of the first AC detection signal SG from the transmission circuit 11 is stopped, and the second AC detection signal SG ′ from the electrode driving circuit 13 serving as the second transmission means built in the CPU 9 is stopped.
- the two-dimensional input operation position of the input operation body 20 is detected by the mutual capacitance method.
- the potential vibration of the vibration power supply circuit 3 is also stopped, but each circuit component mounted on the vibration side circuit board 2 is connected to the DC power supply 16 via the coils 5 and 6.
- one of the plurality of X detection electrodes 10X or the plurality of Y detection electrodes 10Y receives the drive signal D (n) to which the second AC detection signal SG ′ is applied, and the other receives the second AC detection signal SG ′.
- the detection electrode S (m) for detecting the level Vi is received, and the second AC detection signal SG ′ is received at the intersections (n, m) of all the drive electrodes D (n) and the detection electrodes S (m) on the input operation surface. Detect level Vi.
- the reception level Vi appearing on the detection electrode S (m) decreases because a part of the second AC detection signal SG ′ flows to the input operation body 20 and decreases.
- the two-dimensional input operation position of the input operation body 20 is detected from the wiring positions in the XY directions of the drive electrode D (n) and the detection electrode S (m) that intersect at the intersection (n, m).
- the switching control circuit 12 switches the X-side analog multiplexer XMUX to switch the electrode driving circuit 13 to each X detection electrode 10X by using the plurality of X detection electrodes 10X as the drive electrodes D (n).
- the second AC detection signal SG ′ is applied in order to each X detection electrode 10X.
- the output level Vs and the AC frequency of the second AC detection signal SG ′ are arbitrary, but here the detection circuit of the first detection circuit is shared for detection of the reception level Vi, and therefore the output level Vs of the first AC detection signal SG. And the frequency f.
- the electrode drive circuit 13 is replaced by the transmission circuit 11 and the first AC detection signal SG is changed to the second AC detection signal SG. You may make it apply to each X detection electrode 10X as alternating current detection signal SG '.
- the switching control circuit 12 switches and controls the Y-side analog multiplexer YMUX, and the drive electrode D All the Y detection electrodes 10Y insulated and intersecting with (n) are connected in order to the amplifier circuit 8, and set as a detection electrode S (m) for detecting the reception level Vi of the second AC detection signal SG ′.
- the second AC detection signal SG ′ reception level Vi appearing at the detection electrode S (m) at all the intersections (n, m) is amplified by the amplifier circuit 8 and then input to the A / D converter ADC.
- the A / D converter ADC samples at a frequency that is at least twice the natural frequency f of the second AC detection signal SG ′, quantizes the reception level Vi of the second AC detection signal SG ′, and coordinates the CPU 9. 14 to output.
- the switching control circuit 12 of the CPU 9 repeats the same switching control during one scanning period, and sequentially receives the reception levels Vi detected at the intersections (n, m) of all the X detection electrodes 10X and the Y detection electrodes 10Y. 14 to output.
- the reception level Vi detected at each intersection (n, m) represents the amount of change in mutual capacitance between the drive electrode D (n) and the detection electrode S (m) that intersect at the intersection (n, m).
- the coordinate calculation circuit 14 sets the reception levels Vi detected for all the intersections (n, m) in the X direction that is the arrangement order of the X detection electrodes 10X and the Y direction that is the arrangement order of the Y detection electrodes 10Y. And an input operation is performed in the vicinity of the intersection (n, m) where the minimum value is detected, and reception is detected for the surrounding intersection (n, m) including the intersection (n, m).
- a two-dimensional input operation position in the XY direction is detected from the center of gravity in the XY direction of the level Vi.
- the reception level Vi is detected for all the intersections (n, m) even in the so-called multi-touch operation in which the two fingers 20 are simultaneously touched on the input operation surface to perform the input operation. Only the intersection (n, m) at which the reception level Vi becomes the minimum value by the input operation of the finger 20 can be detected, there is no problem of ghost generation, and a plurality of two-dimensional input operation positions can be detected accurately.
- the CPU 9 also sets the input operation positions for the plurality of input operation positions detected by operating the second detection circuit by USB communication, I 2 C communication or the like via the signal line 19 in which the direct current is insulated from the interface circuit 15. Output to the higher-level device to be used.
- the transmission circuit 11 stops transmitting the first AC detection signal SG, and the output impedance of the transmission circuit 11 viewed from the capacitors 17 and 18 side is set to a low impedance. Therefore, a low-pass filter including coils 5 and 6 and capacitors 17 and 18 is formed between the vibration power supply circuit 3 and the reference power supply circuit 4, and each circuit component mounted on the DC power supply 16 side and the vibration side circuit board 2. High frequency noise is not transmitted to the other party.
- the operation of the capacitive touch panel 1 configured as described above will be described with reference to the flowchart of FIG. In a standby state where no input operation is performed, the first detection circuit is operating (step S1).
- the vibration power supply circuit 3 In the operation of the first detection circuit, only the potential of the vibration power supply circuit 3 is vibrated, and no current flows between the high-voltage vibration power supply line SVCC and the low-voltage vibration power supply line SGND or between the high-voltage reference power supply line VCC and the low-voltage reference power supply line GND. Therefore, it is possible to detect an input operation with very little power consumption.
- step S2 When the sum of the quantized data representing the reception level Vi detected for the specific detection electrode 10 is equal to or greater than a predetermined threshold, it is assumed that there has been an input operation approaching the input operation surface, and one scanning period Two-dimensional or three-dimensional input operation positions including the Z direction away from the input operation surface are detected from the reception levels Vi of the plurality of detection electrodes 10 in which the sum of quantized data exceeds a predetermined threshold value (step S2). . If the number of detection electrodes 10 in which the total sum of quantized data exceeds a predetermined threshold is less than 1 during one scanning period of step S2, it is determined that the input operation has been erroneously detected or the input operation has been completed, and the input operation is waited. Return to the state (step S1).
- step S3 it is determined whether the input operation position detected in step S2 is one place or a plurality of places. If a plurality of input operation positions are detected, a plurality of fingers (input operation bodies) are detected. )
- the second detection circuit is activated by assuming that a multi-tap operation to bring 20 into contact with the input operation surface is attempted (step S4). If the input operation position is a single input operation position, the detected input operation is detected. After outputting the position to the host device (step S5), the process returns to step S2, and the detection of the input operation position where the first detection circuit is operated is repeated.
- step S2 in which the input operation position is detected by operating the first detection circuit, the input operation position is detected even in a so-called hover operation in which the input operation body 20 is operated while being away from the input operation surface.
- the multi-touch operation can be detected at the stage of the hover operation, and the second detection circuit can be activated before the input operation body 20 contacts the input operation surface.
- the first detection circuit operates to detect the input operation position even after the input operation body 20 touches the input operation surface, so that the two-dimensional input operation is performed at high speed and with high accuracy. The position can be detected.
- step S6 When the second detection circuit is activated in step S4, it is determined whether or not one or more input operation positions are detected within a predetermined time by the second detection circuit (step S6), and a plurality of scanning cycles are determined. If the input operation position is not detected within the predetermined repeated time, it is determined that the input operation has ended, and the process returns to the standby state of the input operation (step S1).
- the predetermined time is set to a time slightly longer than the operation time from when the hover operation is detected by the first detection circuit until the input operation surface is touched. Thereby, even if the input operation body 20 exists in the input operation position before reaching the input operation surface which can be detected by the second detection circuit, it is not erroneously determined that the input operation has been completed.
- step S7 When one or more input operation positions are detected by the second detection circuit, all detected input operation positions are output to the host device regardless of the number of detections (step S7), and the process returns to step S6.
- the detection of the input operation position where the second detection circuit is operated is repeated.
- the mutual detection type second detection circuit that does not cause a ghost problem is activated before the plurality of input operation bodies 20 intended for multi-touch operation come into contact with the input operation surface.
- the two-dimensional input operation position can be detected promptly without any time delay due to switching.
- the same detection electrode 10 wired along the input operation surface is shared by the first detection circuit and the second detection circuit of the two types of detection methods, and each detection electrode 10 As the means for detecting the reception level Vi that appears, the circuit such as the Y-side analog multiplexer YMUX, the amplifier circuit 8, the A / D converter ADC, and the switching control circuit 12 is also used, so that without significant structural changes or addition of circuit parts, The first detection circuit and the second detection circuit can be selectively operated. Furthermore, according to the present embodiment, when the input operation position is detected by the first detection circuit, all the detection electrodes 10 are connected to the vibration power supply circuit 3 and the first input operation body 20 is collectively connected to the first operation body 20.
- the first AC detection signal SG Since it vibrates at the output level Vs of the AC detection signal SG, there is no need for drive control to apply the first AC detection signal SG for each detection electrode 10 that detects the reception level Vi, and one scanning cycle is shortened, resulting in higher speed.
- the input operation position can be detected. However, if the first AC detection signal SG whose relative potential varies between the detection electrode 10 and the input operation body 20 is generated, the first AC detection signal SG is detected for each detection electrode 10 that detects the reception level Vi. It may be applied, or the potential of the input operation body 20 side may be changed by the first AC detection signal SG.
- the input operation position of a normal input operation that is not a multi-touch operation is detected by operating the first detection circuit, but the input operation body 20 is in contact with the input operation surface.
- the operation operation position may be detected by operating the second detection circuit regardless of the multi-touch operation.
- the present invention is suitable for a capacitive touch panel that recognizes a multi-touch operation and detects a plurality of input operation positions.
- Capacitive Touch Panel 3 Vibration Power Supply Circuit 4 Reference Power Supply Circuit 5 Coil (Second Inductor) 6 Coil (first inductor) 10X X detection electrode (first electrode) 10Y Y detection electrode (second electrode) 11 Transmission circuit (first transmission means) 13 Electrode drive circuit (second transmission means) 14 Coordinate operation circuit (first detection circuit, second detection circuit) 16 DC power supply (DC power supply) 17 Capacitor (first capacitor) 18 Capacitor (second capacitor)
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Abstract
In the present invention, with a regular input operation, a first detection circuit is activated, distances d between detection electrodes and a pointing device are derived directly from reception levels Vi of first alternating current detection signals which manifest in the detection electrodes, and an input operation position is detected. When a multitouch operation is detected with the first detection circuit, a mutual capacitance second detection circuit is activated and the input operation positions are detected, allowing detection of each of the input operation positions of the multitouch operation without the problem of ghost points occurring.
Description
本発明は、入力操作体が接近することにより入力操作体との静電容量が変化する検出電極の入力操作面上の配置位置から、入力操作位置を検出する静電容量式タッチパネルに関し、更に詳しくは、入力操作面上の複数の位置を同時に入力操作する、いわゆる、マルチタッチ操作があっても、各入力操作位置を正確に検出する静電容量式タッチパネルに関する。
The present invention relates to a capacitive touch panel that detects an input operation position from an arrangement position of a detection electrode on an input operation surface, in which the capacitance with the input operation body changes as the input operation body approaches. Relates to a capacitive touch panel that accurately detects each input operation position even when there is a so-called multi-touch operation in which a plurality of positions on the input operation surface are input simultaneously.
静電容量式タッチパネルの入力操作位置の検出方式には、例えば、特表2013−534343号公報(特許文献1)にみられるように、入力操作体が接近することにより浮遊容量が増大する検出電極を検出し、複数の検出電極についての浮遊容量の変化量を比較する重心から入力操作位置を検出する自己容量方式(1線式)と、特表2012−502397号公報(特許文献2)にみられるように、駆動電極へ所定電圧レベルの交流検出信号を加え、駆動電極と入力操作体が接近することにより交流検出信号の受信レベルが低下する検出電極との交差位置から入力操作位置を検出する相互容量方式(2線式)とに分けられる。
自己容量方式では、入力操作面に沿った第1方向と第2方向に、それぞれ互いに絶縁された複数の検出電極を配線するだけで、駆動電極を配線しないので構造が簡略化され、また、各検出電極の配線数だけ走査すれば第1方向と第2方向の入力操作位置を検出できるのでスキャン時間が短く、消費電力が小さいというメリットがあるが、検出した自己容量から入力操作体の入力操作位置を一カ所に絞ることが困難で、入力操作面の二カ所以上の位置を同時に入力操作するマルチタッチ操作では、実際の入力操作位置の他に、第1方向と第2方向の異なる位置を入力操作位置と誤検出する「ゴースト発生」の問題が生じる。
一方、相互容量方式は、第1方向に配線される複数の第1検出電極と第2方向に配線される第2検出電極を互いに絶縁して絶縁パネルの入力操作面に沿って配線し、その一方を交流検出信号を加える駆動電極、他方を交流検出信号の受信レベルを検出する検出電極とする走査を、駆動電極と検出電極の交差位置の全てについて行い、受信レベルが低下した検出電極と駆動電極の交差位置から第1方向と第2方向での入力操作位置を検出する。従って、マルチタッチ操作があっても、それぞれの入力操作位置を正確に検出し、ゴースト発生の問題はないが、第1検出電極と第2検出電極の交差位置の全てについて走査するので、スキャン時間が長くなり入力操作の応答速度が低下するとともに消費電力も増大する。
そこで、自己容量方式と相互容量方式を検出の目的によって切り替え可能とした静電容量センサも知られている(特開2015−31552号公報(特許文献3))。以下、この従来の静電容量センサ100の動作を図6と図7を用いて説明する。図6と図7において、101は、交流検出信号を発信する送信回路、102は、電圧計からなり、交流検出信号の受信レベルを検出する受信回路、103は、入力操作面に配置された駆動電極と検出電極を兼ねた送信電極、104は、入力操作面の送信電極103の近傍に配置された検出電極となる受信電極、107は、送信回路101から送信電極103の方向を順方向としてその間に接続されたダイオード、108は、相互容量方式で受信電極104の電位を検出するための接地容量である。
静電容量センサ100を自己容量方式で動作させて、被検知物(入力操作体)110を検出する場合には、図6に示すように、送信電極103と受信回路102間の開閉器105をON、受信電極104と受信回路102間の開閉器106をOFFとする。送信回路101から送信電極103へ交流検出信号を発信し、送信電極103に被検知物110が接近していると、その間の自己容量(静電容量)120が交流検出信号によって充電される。送信電極103の電位は、この静電容量が充電されることにより徐々に上昇し、開閉器105がONとなり送信電極103に接続する受信回路102は、上昇する送信電極103の電位が一定電位に達するまでの経過時間を検出する。
送信電極103と被検知物110間の静電容量120は、その間の距離に反比例するので、被検知物110が送信電極103に接近するほど大きくなり、交流検出信号により静電容量120を充電して上昇する送信電極103の電位の上昇速度も遅くなり、受信回路102が検出する経過時間が長くなる。従って、静電容量センサ100は、受信回路102が検出する経過時間が長くなることから送信電極103へ被検知物110が接近したことを検知する。
また、静電容量センサ100を相互容量方式で動作させて、被検知物(入力操作体)110を検出する場合には、図7に示すように、送信電極103と受信回路102間の開閉器105をOFF、受信電極104と受信回路102間の開閉器106をONとする。送信回路101から送信電極103へ交流検出信号を発信すると、直列に接続された送信電極103と受信電極104の間の相互容量(静電容量)130と接地容量108からなる合成容量を充電し、受信電極104若しくは接地容量108の高圧側の電位は充電により徐々に上昇し、接地容量108の高圧側に接続する受信回路102は、この上昇する電位が一定電位に達するまでの経過時間を検出する。
送信電極103と受信電極104の間に被検知物110が存在していない場合には、交流検出信号による電流が直列に接続する相互容量(静電容量)130と接地容量108との合成容量を充電するが、被検知物110が電極103、104間に接近すると、その一部が送信電極103から被検知物110に流れ、相互容量(静電容量)130が減少するので、接地容量108との合成容量も減少し、充電速度が増して、受信回路102で検出する経過時間が短くなる。従って、静電容量センサ100は、受信回路102が検出する経過時間が短縮することから、送信電極103と受信電極104に被検知物110が接近したことを検出し、その送信電極103と受信電極104の配置位置から被検知物110の位置を検出する。
この静電容量センサ100の自己容量方式は、入力操作面の送信電極103に被検知物110が達する前の接近した状態を検出できるが、受信回路102が検出する経過時間が長くなることから被検知物110の接近を検出するので、検出時間が長い。一方、相互容量方式は、送信電極103と受信電極104の間に被検知物110が接近するまで被検知物110を検出できないが、受信回路102が検出する経過時間が短くなることから被検知物110の接近を検出するので、検出時間が短く、高速に移動する被検知物110を検知できる。そこで、静電容量センサ100は、自己容量方式と相互容量方式の動作を切り替えて、通常は自己容量方式で被検知物110の接近を検出し、被検知物110の接近が検出された後は、相互容量方式の動作に切り替えて高速に移動する被検知物の移動を検出している。 As the detection method of the input operation position of the capacitive touch panel, for example, as shown in JP 2013-534343 A (Patent Document 1), a detection electrode in which stray capacitance increases as the input operation body approaches The self-capacitance method (one-wire method) that detects the input operation position from the center of gravity for comparing the amount of change in stray capacitance for a plurality of detection electrodes, and Japanese Patent Publication No. 2012-502397 (Patent Document 2) As described above, an AC detection signal of a predetermined voltage level is applied to the drive electrode, and the input operation position is detected from the intersection position of the detection electrode where the reception level of the AC detection signal is lowered when the drive electrode approaches the input operation body. It is divided into the mutual capacity method (two-wire type).
In the self-capacitance method, only the plurality of detection electrodes insulated from each other are wired in the first direction and the second direction along the input operation surface, and the drive electrode is not wired, so that the structure is simplified. If the number of detection electrode wirings is scanned, the input operation positions in the first direction and the second direction can be detected, so that there is an advantage in that the scan time is short and the power consumption is small. In a multi-touch operation in which it is difficult to narrow down the position to one place and two or more positions on the input operation surface are input simultaneously, in addition to the actual input operation position, different positions in the first direction and the second direction are set. There is a problem of “ghosting” that is erroneously detected as the input operation position.
On the other hand, in the mutual capacitance method, the plurality of first detection electrodes wired in the first direction and the second detection electrodes wired in the second direction are insulated from each other and wired along the input operation surface of the insulating panel. Scanning with one drive electrode for applying an AC detection signal and the other electrode for detecting the reception level of the AC detection signal for all the intersection positions of the drive electrode and the detection electrode, and the detection electrode and drive with a lowered reception level Input operation positions in the first direction and the second direction are detected from the intersection positions of the electrodes. Therefore, even if there is a multi-touch operation, each input operation position is accurately detected, and there is no problem of ghosting. However, since all the intersection positions of the first detection electrode and the second detection electrode are scanned, the scan time Becomes longer, the response speed of the input operation decreases, and the power consumption increases.
Therefore, a capacitance sensor that can switch between the self-capacitance method and the mutual capacitance method depending on the purpose of detection is also known (Japanese Patent Laid-Open No. 2015-31552 (Patent Document 3)). The operation of thisconventional capacitance sensor 100 will be described below with reference to FIGS. 6 and 7, 101 is a transmission circuit for transmitting an AC detection signal, 102 is a voltmeter, a reception circuit for detecting the reception level of the AC detection signal, and 103 is a drive arranged on the input operation surface. A transmission electrode serving as both an electrode and a detection electrode, 104 is a reception electrode serving as a detection electrode arranged in the vicinity of the transmission electrode 103 on the input operation surface, and 107 is a forward direction from the transmission circuit 101 to the transmission electrode 103. A diode 108 is connected to a grounding capacitor for detecting the potential of the receiving electrode 104 by a mutual capacitance method.
When thecapacitance sensor 100 is operated by the self-capacitance method to detect the detected object (input operating body) 110, a switch 105 between the transmission electrode 103 and the reception circuit 102 is provided as shown in FIG. ON, the switch 106 between the receiving electrode 104 and the receiving circuit 102 is turned OFF. When an AC detection signal is transmitted from the transmission circuit 101 to the transmission electrode 103 and the detected object 110 approaches the transmission electrode 103, the self-capacitance (capacitance) 120 therebetween is charged by the AC detection signal. The potential of the transmission electrode 103 gradually rises as this capacitance is charged, and the switch 105 is turned on and the reception circuit 102 connected to the transmission electrode 103 has the potential of the rising transmission electrode 103 kept constant. Detect the elapsed time to reach.
Since thecapacitance 120 between the transmission electrode 103 and the detected object 110 is inversely proportional to the distance between them, the capacitance increases as the detected object 110 approaches the transmission electrode 103, and the capacitance 120 is charged by the AC detection signal. As a result, the rising speed of the potential of the transmitting electrode 103 is also slowed down, and the elapsed time detected by the receiving circuit 102 is lengthened. Therefore, the capacitance sensor 100 detects that the detection object 110 has approached the transmission electrode 103 because the elapsed time detected by the reception circuit 102 becomes long.
Further, when detecting the object to be detected (input operation body) 110 by operating thecapacitance sensor 100 in the mutual capacitance method, a switch between the transmission electrode 103 and the reception circuit 102 as shown in FIG. 105 is turned off, and the switch 106 between the receiving electrode 104 and the receiving circuit 102 is turned on. When an AC detection signal is transmitted from the transmission circuit 101 to the transmission electrode 103, a combined capacitance composed of the mutual capacitance (capacitance) 130 and the ground capacitance 108 between the transmission electrode 103 and the reception electrode 104 connected in series is charged. The potential on the high voltage side of the receiving electrode 104 or the grounding capacitor 108 gradually rises due to charging, and the receiving circuit 102 connected to the high voltage side of the grounding capacitor 108 detects the elapsed time until this rising potential reaches a certain potential. .
When theobject 110 to be detected does not exist between the transmission electrode 103 and the reception electrode 104, the combined capacitance of the mutual capacitance (capacitance) 130 and the ground capacitance 108 to which the current due to the AC detection signal is connected in series is set. When the object to be detected 110 approaches between the electrodes 103 and 104, a part of the current flows from the transmission electrode 103 to the object to be detected 110, and the mutual capacitance (capacitance) 130 decreases. The combined capacity is also reduced, the charging speed is increased, and the elapsed time detected by the receiving circuit 102 is shortened. Accordingly, since the elapsed time detected by the reception circuit 102 is shortened, the capacitance sensor 100 detects that the detection object 110 has approached the transmission electrode 103 and the reception electrode 104, and the transmission electrode 103 and the reception electrode. The position of the detected object 110 is detected from the arrangement position 104.
This self-capacitance method of thecapacitance sensor 100 can detect the approached state before the detection object 110 reaches the transmission electrode 103 on the input operation surface, but the elapsed time detected by the reception circuit 102 becomes longer. Since the approach of the detection object 110 is detected, the detection time is long. On the other hand, the mutual capacitance method cannot detect the detected object 110 until the detected object 110 approaches between the transmitting electrode 103 and the receiving electrode 104, but the elapsed time detected by the receiving circuit 102 is shortened. Since the approach of 110 is detected, the detection object 110 that has a short detection time and moves at high speed can be detected. Therefore, the capacitance sensor 100 switches between the self-capacitance method and the mutual capacitance method, and normally detects the approach of the detected object 110 by the self-capacitance method, and after the approach of the detected object 110 is detected. The movement of the detection object that moves at high speed is detected by switching to the operation of the mutual capacitance method.
自己容量方式では、入力操作面に沿った第1方向と第2方向に、それぞれ互いに絶縁された複数の検出電極を配線するだけで、駆動電極を配線しないので構造が簡略化され、また、各検出電極の配線数だけ走査すれば第1方向と第2方向の入力操作位置を検出できるのでスキャン時間が短く、消費電力が小さいというメリットがあるが、検出した自己容量から入力操作体の入力操作位置を一カ所に絞ることが困難で、入力操作面の二カ所以上の位置を同時に入力操作するマルチタッチ操作では、実際の入力操作位置の他に、第1方向と第2方向の異なる位置を入力操作位置と誤検出する「ゴースト発生」の問題が生じる。
一方、相互容量方式は、第1方向に配線される複数の第1検出電極と第2方向に配線される第2検出電極を互いに絶縁して絶縁パネルの入力操作面に沿って配線し、その一方を交流検出信号を加える駆動電極、他方を交流検出信号の受信レベルを検出する検出電極とする走査を、駆動電極と検出電極の交差位置の全てについて行い、受信レベルが低下した検出電極と駆動電極の交差位置から第1方向と第2方向での入力操作位置を検出する。従って、マルチタッチ操作があっても、それぞれの入力操作位置を正確に検出し、ゴースト発生の問題はないが、第1検出電極と第2検出電極の交差位置の全てについて走査するので、スキャン時間が長くなり入力操作の応答速度が低下するとともに消費電力も増大する。
そこで、自己容量方式と相互容量方式を検出の目的によって切り替え可能とした静電容量センサも知られている(特開2015−31552号公報(特許文献3))。以下、この従来の静電容量センサ100の動作を図6と図7を用いて説明する。図6と図7において、101は、交流検出信号を発信する送信回路、102は、電圧計からなり、交流検出信号の受信レベルを検出する受信回路、103は、入力操作面に配置された駆動電極と検出電極を兼ねた送信電極、104は、入力操作面の送信電極103の近傍に配置された検出電極となる受信電極、107は、送信回路101から送信電極103の方向を順方向としてその間に接続されたダイオード、108は、相互容量方式で受信電極104の電位を検出するための接地容量である。
静電容量センサ100を自己容量方式で動作させて、被検知物(入力操作体)110を検出する場合には、図6に示すように、送信電極103と受信回路102間の開閉器105をON、受信電極104と受信回路102間の開閉器106をOFFとする。送信回路101から送信電極103へ交流検出信号を発信し、送信電極103に被検知物110が接近していると、その間の自己容量(静電容量)120が交流検出信号によって充電される。送信電極103の電位は、この静電容量が充電されることにより徐々に上昇し、開閉器105がONとなり送信電極103に接続する受信回路102は、上昇する送信電極103の電位が一定電位に達するまでの経過時間を検出する。
送信電極103と被検知物110間の静電容量120は、その間の距離に反比例するので、被検知物110が送信電極103に接近するほど大きくなり、交流検出信号により静電容量120を充電して上昇する送信電極103の電位の上昇速度も遅くなり、受信回路102が検出する経過時間が長くなる。従って、静電容量センサ100は、受信回路102が検出する経過時間が長くなることから送信電極103へ被検知物110が接近したことを検知する。
また、静電容量センサ100を相互容量方式で動作させて、被検知物(入力操作体)110を検出する場合には、図7に示すように、送信電極103と受信回路102間の開閉器105をOFF、受信電極104と受信回路102間の開閉器106をONとする。送信回路101から送信電極103へ交流検出信号を発信すると、直列に接続された送信電極103と受信電極104の間の相互容量(静電容量)130と接地容量108からなる合成容量を充電し、受信電極104若しくは接地容量108の高圧側の電位は充電により徐々に上昇し、接地容量108の高圧側に接続する受信回路102は、この上昇する電位が一定電位に達するまでの経過時間を検出する。
送信電極103と受信電極104の間に被検知物110が存在していない場合には、交流検出信号による電流が直列に接続する相互容量(静電容量)130と接地容量108との合成容量を充電するが、被検知物110が電極103、104間に接近すると、その一部が送信電極103から被検知物110に流れ、相互容量(静電容量)130が減少するので、接地容量108との合成容量も減少し、充電速度が増して、受信回路102で検出する経過時間が短くなる。従って、静電容量センサ100は、受信回路102が検出する経過時間が短縮することから、送信電極103と受信電極104に被検知物110が接近したことを検出し、その送信電極103と受信電極104の配置位置から被検知物110の位置を検出する。
この静電容量センサ100の自己容量方式は、入力操作面の送信電極103に被検知物110が達する前の接近した状態を検出できるが、受信回路102が検出する経過時間が長くなることから被検知物110の接近を検出するので、検出時間が長い。一方、相互容量方式は、送信電極103と受信電極104の間に被検知物110が接近するまで被検知物110を検出できないが、受信回路102が検出する経過時間が短くなることから被検知物110の接近を検出するので、検出時間が短く、高速に移動する被検知物110を検知できる。そこで、静電容量センサ100は、自己容量方式と相互容量方式の動作を切り替えて、通常は自己容量方式で被検知物110の接近を検出し、被検知物110の接近が検出された後は、相互容量方式の動作に切り替えて高速に移動する被検知物の移動を検出している。 As the detection method of the input operation position of the capacitive touch panel, for example, as shown in JP 2013-534343 A (Patent Document 1), a detection electrode in which stray capacitance increases as the input operation body approaches The self-capacitance method (one-wire method) that detects the input operation position from the center of gravity for comparing the amount of change in stray capacitance for a plurality of detection electrodes, and Japanese Patent Publication No. 2012-502397 (Patent Document 2) As described above, an AC detection signal of a predetermined voltage level is applied to the drive electrode, and the input operation position is detected from the intersection position of the detection electrode where the reception level of the AC detection signal is lowered when the drive electrode approaches the input operation body. It is divided into the mutual capacity method (two-wire type).
In the self-capacitance method, only the plurality of detection electrodes insulated from each other are wired in the first direction and the second direction along the input operation surface, and the drive electrode is not wired, so that the structure is simplified. If the number of detection electrode wirings is scanned, the input operation positions in the first direction and the second direction can be detected, so that there is an advantage in that the scan time is short and the power consumption is small. In a multi-touch operation in which it is difficult to narrow down the position to one place and two or more positions on the input operation surface are input simultaneously, in addition to the actual input operation position, different positions in the first direction and the second direction are set. There is a problem of “ghosting” that is erroneously detected as the input operation position.
On the other hand, in the mutual capacitance method, the plurality of first detection electrodes wired in the first direction and the second detection electrodes wired in the second direction are insulated from each other and wired along the input operation surface of the insulating panel. Scanning with one drive electrode for applying an AC detection signal and the other electrode for detecting the reception level of the AC detection signal for all the intersection positions of the drive electrode and the detection electrode, and the detection electrode and drive with a lowered reception level Input operation positions in the first direction and the second direction are detected from the intersection positions of the electrodes. Therefore, even if there is a multi-touch operation, each input operation position is accurately detected, and there is no problem of ghosting. However, since all the intersection positions of the first detection electrode and the second detection electrode are scanned, the scan time Becomes longer, the response speed of the input operation decreases, and the power consumption increases.
Therefore, a capacitance sensor that can switch between the self-capacitance method and the mutual capacitance method depending on the purpose of detection is also known (Japanese Patent Laid-Open No. 2015-31552 (Patent Document 3)). The operation of this
When the
Since the
Further, when detecting the object to be detected (input operation body) 110 by operating the
When the
This self-capacitance method of the
自己容量方式で二次元の2方向の入力操作位置を検出する場合には、上述した「ゴースト発生」の問題が生じるので、特許文献1の静電容量式タッチパネルでは、前記2方向の他に更に異なる方向に多数の補助検出電極を配線し、2以上の入力操作位置を検出した場合には、各補助検出電極についての静電容量の変化から、実際にマルチタッチした入力操作位置を判別している。しかしながら、この方法は、2方向の検出電極の他に更に異なる方向の複数の補助検出電極を全ての検出電極が互いに絶縁するように配線しなければならず、静電容量式タッチパネルの構造が極めて複雑化するので実用的ではない。
相互容量方式で入力操作位置を検出すれば、ゴースト発生の問題がなく、マルチタッチ操作による各入力操作位置を検出できるので、自己容量方式と相互容量方式を検出用途に応じて切り替える特許文献3に記載の発明と組み合わせて、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替える静電容量式タッチパネルが検討された。
しかしながら、特許文献1と特許文献3に開示されているように、従来の自己容量方式で入力操作体の入力操作位置を検出する場合には、入力操作体と交流検出信号を印加する検出電極間の静電容量の変化量に応じて変化する所定の充電電位に達するまでの経過時間から、検出電極と入力操作体間の距離を求めるので、入力操作体と検出電極間の距離は、入力操作体と検出電極間の静電容量に反比例するものの、実際に検出する経過時間との線形性がなく、経過時間から高精度に検出電極と入力操作体間の距離を検出することができない。
特に、特許文献1に記載のように二次元の2方向の入力操作位置を検出する場合には、2方向にそれぞれ配線される各検出電極についての静電容量の変化量の重心から入力操作体の2方向の入力操作位置を検出することとなり、各検出電極についての静電容量の変化量を表す経過時間には入力操作体との距離と線形性がないので、その重心から求める入力操作位置の精度は悪化する。従って、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替えるとしても、マルチタッチ操作を検出しない通常の入力操作位置の検出に、自己容量方式を採用することはできない。
更に、自己容量方式の静電容量式タッチパネルでは、上述のように入力操作位置の検出精度が悪いので、マルチタッチ操作自体を検出することが困難で、少なくとも2以上の入力操作体が入力操作面に接触する程度まで接近しなければ、2以上の独立した入力操作位置を検出することができず、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替えるとしても、ゴースト発生の問題が生じない相互容量方式への切り替えが遅れるものとなる。
一方、特許文献2に示される相互容量方式によれば、ゴースト発生の問題がなく、高い精度で入力操作位置を検出することができるが、二次元の2方向の入力操作位置を検出する場合には、第1方向に配線される複数の駆動電極と第2方向に配線される複数の検出電極の全ての交差位置について、静電容量の変化を検出する走査を行う必要があり、二次元の入力操作位置を高速に検出することができない。この問題は、タッチパネルの入力操作面が拡大し、多数の駆動電極と検出電極を配線する必要がある場合により顕著となるので、マルチタッチ操作の検出有無にかかわらず、常に相互容量方式を採用することにも問題がある。
本発明は、このような従来の問題点を考慮してなされたものであり、マルチタッチ操作ではない通常の入力操作の入力操作位置を高速に高精度に検出する静電容量式タッチパネルを提供することを目的とする。
また、マルチタッチ操作を検出した場合には、入力操作体が入力操作面に触れる前に、ゴースト発生の問題がない相互容量方式に切り替える静電容量式タッチパネルを提供することを目的とする。
3 When the two-dimensional two-direction input operation position is detected by the self-capacitance method, the above-mentioned “ghost generation” problem occurs. When a large number of auxiliary detection electrodes are wired in different directions and two or more input operation positions are detected, the input operation position actually multi-touched is determined from the change in capacitance of each auxiliary detection electrode. Yes. However, in this method, in addition to the detection electrodes in two directions, a plurality of auxiliary detection electrodes in different directions must be wired so that all the detection electrodes are insulated from each other. It is not practical because it is complicated.
If the input operation position is detected by the mutual capacitance method, there is no problem of ghost generation, and each input operation position by the multi-touch operation can be detected. Therefore,Patent Document 3 switches between the self-capacitance method and the mutual capacitance method according to the detection application. In combination with the described invention, a capacitive touch panel that switches from the self-capacitance method to the mutual capacitance method only when a multi-touch operation is detected has been studied.
However, as disclosed inPatent Document 1 and Patent Document 3, when the input operation position of the input operation body is detected by the conventional self-capacitance method, between the input operation body and the detection electrode to which the AC detection signal is applied. Since the distance between the detection electrode and the input operation body is obtained from the elapsed time until reaching a predetermined charging potential that changes according to the amount of change in the capacitance of the input, the distance between the input operation body and the detection operation electrode Although it is inversely proportional to the capacitance between the body and the detection electrode, there is no linearity with the elapsed time that is actually detected, and the distance between the detection electrode and the input operation body cannot be detected with high accuracy from the elapsed time.
In particular, when a two-dimensional input operation position in two directions is detected as described inPatent Document 1, the input operation object is determined from the center of gravity of the amount of change in capacitance for each detection electrode wired in two directions. The input operation position in two directions is detected, and since there is no linearity and distance from the input operation body in the elapsed time representing the amount of change in capacitance for each detection electrode, the input operation position obtained from its center of gravity The accuracy of. Therefore, even if the self-capacitance method is switched to the mutual capacitance method only when a multi-touch operation is detected, the self-capacitance method cannot be adopted for detecting a normal input operation position that does not detect the multi-touch operation.
Furthermore, since the self-capacitance type capacitive touch panel has poor detection accuracy of the input operation position as described above, it is difficult to detect the multi-touch operation itself. If it is not close enough to touch the touch panel, two or more independent input operation positions cannot be detected. Switching to a mutual capacity system that does not cause a problem will be delayed.
On the other hand, according to the mutual capacitance method disclosed in Patent Document 2, there is no problem of ghost generation, and the input operation position can be detected with high accuracy. However, when the two-dimensional two-direction input operation position is detected. Needs to perform scanning to detect a change in capacitance at all intersection positions of a plurality of drive electrodes wired in the first direction and a plurality of detection electrodes wired in the second direction. The input operation position cannot be detected at high speed. This problem becomes more conspicuous when the input operation surface of the touch panel is enlarged and a large number of drive electrodes and detection electrodes need to be wired. Therefore, the mutual capacitance method is always adopted regardless of whether or not a multi-touch operation is detected. There is also a problem.
The present invention has been made in consideration of such conventional problems, and provides a capacitive touch panel that detects an input operation position of a normal input operation that is not a multi-touch operation at high speed and with high accuracy. For the purpose.
It is another object of the present invention to provide a capacitive touch panel that switches to a mutual capacitance method that does not cause a ghost problem before the input operation body touches the input operation surface when a multi-touch operation is detected.
3
相互容量方式で入力操作位置を検出すれば、ゴースト発生の問題がなく、マルチタッチ操作による各入力操作位置を検出できるので、自己容量方式と相互容量方式を検出用途に応じて切り替える特許文献3に記載の発明と組み合わせて、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替える静電容量式タッチパネルが検討された。
しかしながら、特許文献1と特許文献3に開示されているように、従来の自己容量方式で入力操作体の入力操作位置を検出する場合には、入力操作体と交流検出信号を印加する検出電極間の静電容量の変化量に応じて変化する所定の充電電位に達するまでの経過時間から、検出電極と入力操作体間の距離を求めるので、入力操作体と検出電極間の距離は、入力操作体と検出電極間の静電容量に反比例するものの、実際に検出する経過時間との線形性がなく、経過時間から高精度に検出電極と入力操作体間の距離を検出することができない。
特に、特許文献1に記載のように二次元の2方向の入力操作位置を検出する場合には、2方向にそれぞれ配線される各検出電極についての静電容量の変化量の重心から入力操作体の2方向の入力操作位置を検出することとなり、各検出電極についての静電容量の変化量を表す経過時間には入力操作体との距離と線形性がないので、その重心から求める入力操作位置の精度は悪化する。従って、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替えるとしても、マルチタッチ操作を検出しない通常の入力操作位置の検出に、自己容量方式を採用することはできない。
更に、自己容量方式の静電容量式タッチパネルでは、上述のように入力操作位置の検出精度が悪いので、マルチタッチ操作自体を検出することが困難で、少なくとも2以上の入力操作体が入力操作面に接触する程度まで接近しなければ、2以上の独立した入力操作位置を検出することができず、マルチタッチ操作を検出した場合にのみ自己容量方式から相互容量方式へ切り替えるとしても、ゴースト発生の問題が生じない相互容量方式への切り替えが遅れるものとなる。
一方、特許文献2に示される相互容量方式によれば、ゴースト発生の問題がなく、高い精度で入力操作位置を検出することができるが、二次元の2方向の入力操作位置を検出する場合には、第1方向に配線される複数の駆動電極と第2方向に配線される複数の検出電極の全ての交差位置について、静電容量の変化を検出する走査を行う必要があり、二次元の入力操作位置を高速に検出することができない。この問題は、タッチパネルの入力操作面が拡大し、多数の駆動電極と検出電極を配線する必要がある場合により顕著となるので、マルチタッチ操作の検出有無にかかわらず、常に相互容量方式を採用することにも問題がある。
本発明は、このような従来の問題点を考慮してなされたものであり、マルチタッチ操作ではない通常の入力操作の入力操作位置を高速に高精度に検出する静電容量式タッチパネルを提供することを目的とする。
また、マルチタッチ操作を検出した場合には、入力操作体が入力操作面に触れる前に、ゴースト発生の問題がない相互容量方式に切り替える静電容量式タッチパネルを提供することを目的とする。
3 When the two-dimensional two-direction input operation position is detected by the self-capacitance method, the above-mentioned “ghost generation” problem occurs. When a large number of auxiliary detection electrodes are wired in different directions and two or more input operation positions are detected, the input operation position actually multi-touched is determined from the change in capacitance of each auxiliary detection electrode. Yes. However, in this method, in addition to the detection electrodes in two directions, a plurality of auxiliary detection electrodes in different directions must be wired so that all the detection electrodes are insulated from each other. It is not practical because it is complicated.
If the input operation position is detected by the mutual capacitance method, there is no problem of ghost generation, and each input operation position by the multi-touch operation can be detected. Therefore,
However, as disclosed in
In particular, when a two-dimensional input operation position in two directions is detected as described in
Furthermore, since the self-capacitance type capacitive touch panel has poor detection accuracy of the input operation position as described above, it is difficult to detect the multi-touch operation itself. If it is not close enough to touch the touch panel, two or more independent input operation positions cannot be detected. Switching to a mutual capacity system that does not cause a problem will be delayed.
On the other hand, according to the mutual capacitance method disclosed in Patent Document 2, there is no problem of ghost generation, and the input operation position can be detected with high accuracy. However, when the two-dimensional two-direction input operation position is detected. Needs to perform scanning to detect a change in capacitance at all intersection positions of a plurality of drive electrodes wired in the first direction and a plurality of detection electrodes wired in the second direction. The input operation position cannot be detected at high speed. This problem becomes more conspicuous when the input operation surface of the touch panel is enlarged and a large number of drive electrodes and detection electrodes need to be wired. Therefore, the mutual capacitance method is always adopted regardless of whether or not a multi-touch operation is detected. There is also a problem.
The present invention has been made in consideration of such conventional problems, and provides a capacitive touch panel that detects an input operation position of a normal input operation that is not a multi-touch operation at high speed and with high accuracy. For the purpose.
It is another object of the present invention to provide a capacitive touch panel that switches to a mutual capacitance method that does not cause a ghost problem before the input operation body touches the input operation surface when a multi-touch operation is detected.
3
上述の目的を達成するため、請求項1の静電容量式タッチパネルは、絶縁基板の入力操作面に沿って第1方向に配線される複数の第1検出電極と、入力操作面に沿って第1方向と交差する第2方向に配線される複数の第2検出電極と、第1検出電極と第2検出電極の各検出電極と入力操作体との相対電位が変動する第1交流検出信号を発信する第1発信手段と、各検出電極と入力操作体間の静電容量を介して、各検出電極に表れる第1交流検出信号の受信レベルを検出する第1信号検出手段とを有し、各検出電極毎に検出した第1交流検出信号の受信レベルをもとにその検出電極と入力操作体間の距離を求め、各検出電極の入力操作体との距離を比較して入力操作体の入力操作位置を検出する第1検出回路と、複数の第1検出電極へ順に第2交流検出信号を発信する第2発信手段と、第1検出電極と第2検出電極間の静電容量を介して、第2交流検出信号を発信した第1検出電極に交差する複数の各第2検出電極に表れる第2交流検出信号の受信レベルを検出する第2信号検出手段とを有し、入力操作体が接近し受信レベルが変化する第1検出電極と第2検出電極の絶縁基板上の交差位置から、入力操作面上の入力操作体の入力操作位置を検出する第2検出回路と、第1検出回路が2以上の入力操作体による入力操作位置を検出した場合にマルチタッチ操作と判定する判定手段と、判定手段の判定結果によって第1検出回路と第2検出回路のいずれかの動作に切り替える切替制御回路とを備え、判定手段がマルチタッチ操作と判定しない場合には、第1検出回路を動作させて入力操作面上の入力操作体の入力操作位置を検出し、判定手段がマルチタッチ操作と判定した場合には、第2検出回路を動作させて入力操作面上の2以上の入力操作体の入力操作位置をそれぞれ検出することを特徴とする。
検出電極と入力操作体間の静電容量をCm、検出電極と入力操作体間の距離をd、第1交流検出信号の出力レベルをVs、kを定数として、第1検出回路の検出電極に表れる受信レベルViは、Vi=Vs/(d・k)で表され、検出電極と入力操作体間の距離dに反比例する。従って、第1検出回路は、第1方向に沿って配線される第1検出電極が検出した第1交流検出信号の受信レベルViから、第1方向に直交する方向の第1検出電極と入力操作体間の距離が、第2方向に沿って配線される第2検出電極が検出した第1交流検出信号の受信レベルViから、第2方向に直交する方向の第2検出電極と入力操作体間の距離がそれぞれ得られ、入力操作面に沿った二次元の入力操作位置を検出できる。
判定手段でマルチタッチ操作と判定されない通常の入力操作は、第1検出回路が動作してその入力操作位置を検出する。第1検出回路が各検出電極について検出する受信レベルViの逆数は、検出電極と入力操作体間の距離dと線形性があるので、受信レベルViから入力操作体の入力操作位置を精度良く検出でき、第1検出電極と第2検出電極の総電極数について受信レベルViを検出するだけで入力操作面上の二次元の入力操作位置を検出できる。
第2検出回路は、第2交流検出信号を印加する複数の第1検出電極と第2交流検出信号の受信レベルを検出する複数の第2検出電極の全ての交差位置について、交差位置毎に第2交流検出信号の受信レベルが低下した交差位置で交差する第1検出電極と第2検出電極の配線位置から入力操作面の二次元の入力操作位置を入力操作位置を検出する。第2検出回路によれば、全ての交差位置について入力操作体の接近による第2交流検出信号の受信レベルを検出するので、マルチタッチ操作があってもゴースト発生の問題なく、各入力操作位置を正確に検出できる。
第1検出回路と第2検出回路は、複数の第1検出電極と複数の第2検出電極を兼用するので,構造を大幅に変更することなく、異なる検出方式で入力操作位置を検出できる。
請求項2の静電容量式タッチパネルは、判定手段が、第1検出回路が入力操作面上の入力操作体の入力操作位置を検出する前に、2以上の入力操作体による入力操作位置を検出した場合に、マルチタッチ操作と判定することを特徴とする。
第1検出回路によれば、高精度に入力操作位置を検出できるので、判定手段は、複数の入力操作体が入力操作面から離れていてもマルチタッチ操作と判定することができ、入力操作面をタッチ操作する前に、第2検出回路を起動させて高速にマルチタッチ操作の各入力操作位置を検出できる。
請求項3の静電容量式タッチパネルは、切替制御回路が、判定手段がマルチタッチ操作と判定した場合には、第1検出回路から第2検出回路へ動作を切り替え、第2検出回路が入力操作面上のいずれの入力操作体の入力操作位置も検出しない場合に、第2検出回路から第1検出回路へ動作を切り替えることを特徴とする。
マルチタッチ操作は、第2検出回路が動作して入力操作位置を検出し、マルチタッチ操作の入力操作が終わると第1検出回路が動作するので、入力操作の待機状態では第1検出回路が動作する。
請求項4の静電容量式タッチパネルは、第1検出回路が、更に、一方を接地若しくは定電位とした低圧基準電源線と高圧基準電源線との間に直流電圧を出力する一次直流電源回路と、低圧振動電源線と高圧振動電源線との間から直流電圧を出力する二次直流電源回路と、低圧基準電源線と低圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第1インダクタと、高圧基準電源線と高圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第2インダクタと、二次直流電源回路で動作する第1発信手段と高圧基準電源線及び低圧基準電源線間にそれぞれ接続される第1キャパシタ及び第2キャパシタとを備え、第1検出回路を動作させる間は、第2発信手段の動作を停止し、第1発信手段から、第1キャパシタと第2キャパシタを介して、一次直流電源回路へ第1交流検出信号を出力するとともに、各検出電極を、二次直流電源回路の低圧振動電源線と高圧振動電源線のいずれかに接続して第1交流検出信号の周波数で振動させ、第2検出回路を動作させる間は、第2発信手段から複数の第1検出電極へ順に第2交流検出信号を出力するとともに、第1発信手段の第1キャパシタと第2キャパシタからみた出力インピーダンスを低インピーダンスとして第1発信手段の第1交流検出信号の出力を停止することを特徴とする。
第1検出回路を動作させる間は、一次直流電源回路が、低圧基準電源線と高圧基準電源線の一方は接地若しくは定電位に接続して定電位であるので、二次直流電源回路で動作する第1発信手段から第1キャパシタと第2キャパシタを介して一次直流電源回路に第1交流検出信号が出力すると、二次直流電源回路は、第1交流検出信号の周波数fで相対的に変動する。各検出電極は、二次直流電源回路の低圧振動電源線と高圧振動電源線のいずれかに接続するので、定電位の入力操作体に対して第1交流検出信号の周波数fで相対的に電位を変動する。
第2検出回路を動作させる間は、一次直流電源回路と二次直流電源回路間に、第1インダクタと第1キャパシタ若しくは第2インダクタと第2キャパシタとからローパスフィルタが形成されるので、一次直流電源回路の高周波ノイズが二次直流電源回路に接続する各回路に流れることがなく、また、二次直流電源回路に接続する各回路で発生する高周波ノイズが一次直流電源回路側に流れない。
請求項5の静電容量式タッチパネルの入力操作位置検出方法は、絶縁基板の入力操作面に沿って第1方向に配線される複数の第1検出電極と第1方向と交差する第2方向に配線される複数の第2検出電極の各検出電極に、入力操作体との相対電位が変動する第1交流検出信号を発信し、各検出電極と入力操作体間の静電容量を介して、前記各検出電極に表れる第1交流検出信号の受信レベルを検出し、各検出電極毎に検出した第1交流検出信号の受信レベルをもとにその検出電極と入力操作体間の距離を求め、各検出電極の入力操作体との距離を比較して入力操作体の入力操作位置を検出し、検出した入力操作位置が入力操作面に達するまで、単一の入力操作体による入力操作位置を検出した場合には、その入力操作面上の入力操作体の入力操作位置を検出し、検出した入力操作位置が入力操作面に達する前に、2以上の入力操作体による入力操作位置を検出した場合に、第1交流検出信号の発信を停止するとともに、複数の第1検出電極へ順に第2交流検出信号を発信し、第1検出電極と第2検出電極間の静電容量を介して、第2交流検出信号を発信した第1検出電極に交差する複数の各第2検出電極に表れる第2交流検出信号の受信レベルを検出し、入力操作体が接近し受信レベルが変化する第1検出電極と第2検出電極の絶縁基板上の交差位置から、入力操作面上の入力操作体の入力操作位置を検出することを特徴とする。
検出電極と入力操作体間の静電容量をCm、検出電極と入力操作体間の距離をd、第1交流検出信号の出力レベルをVs、kを定数として、第1検出回路の検出電極に表れる受信レベルViは、Vi=Vs/(d・k)で表され、検出電極と入力操作体間の距離dに反比例する。従って、第1方向に沿って配線される第1検出電極が検出した第1交流検出信号の受信レベルViから、第1方向に直交する方向の第1検出電極と入力操作体間の距離が、第2方向に沿って配線される第2検出電極が検出した第1交流検出信号の受信レベルViから、第2方向に直交する方向の第2検出電極と入力操作体間の距離がそれぞれ得られ、入力操作面に沿った二次元の入力操作位置を検出できる。
検出した入力操作位置が入力操作面に達するまで、単一の入力操作体による入力操作位置である場合には、同じ方法で第1交流検出信号の受信レベルViから入力操作位置を検出する。各検出電極について検出する受信レベルViの逆数は、検出電極と入力操作体間の距離dと線形性があるので、受信レベルViから入力操作体の入力操作位置を精度良く検出でき、第1検出電極と第2検出電極の総電極数について受信レベルViを検出するだけで入力操作面上の二次元の入力操作位置を検出できる。
検出した入力操作位置が入力操作面に達する前に、2以上の入力操作体による入力操作位置を検出した場合には、第1検出電極と第2検出電極の絶縁基板上の交差位置毎に第2交流検出信号の受信レベルを検出し、その受信レベルが変化する交差位置から、入力操作面上の入力操作体の入力操作位置を検出するので、マルチタッチ操作があってもゴースト発生の問題なく、各入力操作位置を正確に検出できる。複数の入力操作体が入力操作面から離れていてもマルチタッチ操作と判定することができ、入力操作面をタッチ操作する前に、異なる入力操作位置の検出方法に切り替えて高速にマルチタッチ操作の各入力操作位置を検出できる。 In order to achieve the above-described object, the capacitive touch panel according toclaim 1 includes a plurality of first detection electrodes wired in a first direction along the input operation surface of the insulating substrate, and a first along the input operation surface. A plurality of second detection electrodes wired in a second direction crossing one direction, and a first AC detection signal in which a relative potential between the first detection electrode, each detection electrode of the second detection electrode, and the input operation body varies. First transmission means for transmitting, and first signal detection means for detecting the reception level of the first AC detection signal appearing on each detection electrode via the capacitance between each detection electrode and the input operation body, Based on the reception level of the first AC detection signal detected for each detection electrode, the distance between the detection electrode and the input operation body is obtained, and the distance between each detection electrode and the input operation body is compared. A first detection circuit for detecting an input operation position, and a plurality of first detection electrodes in order A second transmission means for transmitting a flow detection signal, and a plurality of second intersecting with the first detection electrode for transmitting the second AC detection signal via a capacitance between the first detection electrode and the second detection electrode. And a second signal detecting means for detecting a reception level of the second AC detection signal appearing on the detection electrode, the first detection electrode on which the input operation body approaches and the reception level changes and the second detection electrode on the insulating substrate A second detection circuit that detects the input operation position of the input operation body on the input operation surface from the intersection position, and a multi-touch operation is determined when the first detection circuit detects an input operation position by two or more input operation bodies And a switching control circuit for switching to one of the first detection circuit and the second detection circuit according to the determination result of the determination means, and the first detection is performed when the determination means does not determine the multi-touch operation. Operate the circuit and When the input operation position of the input operation body on the screen is detected and the determination means determines that the operation is a multi-touch operation, the second detection circuit is operated to input the input operation positions of two or more input operation bodies on the input operation surface. Are detected respectively.
The capacitance between the detection electrode and the input operation body is Cm, the distance between the detection electrode and the input operation body is d, the output level of the first AC detection signal is Vs, and k is a constant. The reception level Vi that appears is expressed by Vi = Vs / (d · k), and is inversely proportional to the distance d between the detection electrode and the input operating body. Accordingly, the first detection circuit performs the input operation with the first detection electrode in the direction orthogonal to the first direction from the reception level Vi of the first AC detection signal detected by the first detection electrode wired along the first direction. The distance between the bodies is between the second detection electrode and the input operation body in the direction orthogonal to the second direction from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction. Are obtained, and a two-dimensional input operation position along the input operation surface can be detected.
For a normal input operation that is not determined to be a multi-touch operation by the determination means, the first detection circuit operates to detect the input operation position. Since the reciprocal of the reception level Vi detected for each detection electrode by the first detection circuit is linear with the distance d between the detection electrode and the input operation body, the input operation position of the input operation body is accurately detected from the reception level Vi. It is possible to detect a two-dimensional input operation position on the input operation surface only by detecting the reception level Vi for the total number of first detection electrodes and second detection electrodes.
The second detection circuit includes a first detection electrode that applies the second AC detection signal and a second detection electrode that detects the reception level of the second AC detection signal. (2) The input operation position is detected as a two-dimensional input operation position on the input operation surface from the wiring positions of the first detection electrode and the second detection electrode that intersect at the intersection position where the reception level of the AC detection signal is lowered. According to the second detection circuit, since the reception level of the second AC detection signal due to the approach of the input operation body is detected at all the intersection positions, each input operation position can be determined without causing a ghost even if there is a multi-touch operation. It can be detected accurately.
Since the first detection circuit and the second detection circuit share the plurality of first detection electrodes and the plurality of second detection electrodes, the input operation position can be detected by different detection methods without significantly changing the structure.
In the capacitive touch panel according to claim 2, the determination unit detects an input operation position by two or more input operation bodies before the first detection circuit detects an input operation position of the input operation body on the input operation surface. In this case, it is determined that the operation is a multi-touch operation.
According to the first detection circuit, since the input operation position can be detected with high accuracy, the determination means can determine that the input operation surface is a multi-touch operation even if a plurality of input operation bodies are separated from the input operation surface. Before the touch operation, the second detection circuit can be activated to detect each input operation position of the multi-touch operation at high speed.
In the capacitive touch panel according toclaim 3, when the switching control circuit determines that the multi-touch operation is determined by the determination unit, the operation is switched from the first detection circuit to the second detection circuit, and the second detection circuit performs the input operation. When the input operation position of any input operation body on the surface is not detected, the operation is switched from the second detection circuit to the first detection circuit.
In the multi-touch operation, the second detection circuit operates to detect the input operation position, and when the multi-touch operation input operation ends, the first detection circuit operates. Therefore, the first detection circuit operates in the standby state of the input operation. To do.
The capacitive touch panel according to claim 4, wherein the first detection circuit further includes a primary DC power supply circuit that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line, one of which is grounded or at a constant potential. A secondary DC power supply circuit that outputs a DC voltage from between the low-voltage vibration power supply line and the high-voltage vibration power supply line; and a high impedance for the first AC detection signal that is connected between the low-voltage reference power supply line and the low-voltage vibration power supply line. A first inductor that is connected between the high-voltage reference power supply line and the high-voltage vibration power supply line and that has a high impedance with respect to the first AC detection signal; And a first capacitor and a second capacitor connected between the high-voltage reference power supply line and the low-voltage reference power supply line, respectively, while the first detection circuit is operated, the operation of the second transmission means is stopped and the first transmission is performed. hand From the first capacitor and the second capacitor, the first AC detection signal is output to the primary DC power supply circuit, and each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit. The second AC detection signal is sequentially output from the second transmission means to the plurality of first detection electrodes while the second detection circuit is operated by connecting to the first AC detection signal and vibrating at the frequency of the first AC detection signal. The output impedance viewed from the first capacitor and the second capacitor of the first transmission means is set to a low impedance, and the output of the first AC detection signal of the first transmission means is stopped.
While operating the first detection circuit, the primary DC power supply circuit operates with the secondary DC power supply circuit because one of the low-voltage reference power supply line and the high-voltage reference power supply line is connected to the ground or a constant potential and has a constant potential. When the first AC detection signal is output from the first transmitting means to the primary DC power supply circuit via the first capacitor and the second capacitor, the secondary DC power supply circuit relatively fluctuates at the frequency f of the first AC detection signal. . Since each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit, the potential relative to the constant potential input operation body at the frequency f of the first AC detection signal is relatively high. Fluctuate.
While the second detection circuit is operated, a low-pass filter is formed between the primary DC power supply circuit and the secondary DC power supply circuit from the first inductor and the first capacitor or the second inductor and the second capacitor. The high frequency noise of the power supply circuit does not flow to each circuit connected to the secondary DC power supply circuit, and the high frequency noise generated in each circuit connected to the secondary DC power supply circuit does not flow to the primary DC power supply circuit side.
According to a fifth aspect of the present invention, there is provided a capacitive touch panel input operation position detection method in a second direction intersecting the first direction with a plurality of first detection electrodes wired in the first direction along the input operation surface of the insulating substrate. A first AC detection signal whose relative potential with the input operation body varies is transmitted to each detection electrode of the plurality of second detection electrodes to be wired, and through the capacitance between each detection electrode and the input operation body, Detecting the reception level of the first AC detection signal appearing on each detection electrode, and determining the distance between the detection electrode and the input operating body based on the reception level of the first AC detection signal detected for each detection electrode; The input operation position of the input operation body is detected by comparing the distance between each detection electrode and the input operation body, and the input operation position by a single input operation body is detected until the detected input operation position reaches the input operation surface. Input, the input of the input operation body on the input operation surface When the operation position is detected and the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the transmission of the first AC detection signal is stopped and a plurality of input operation positions are stopped. A second AC detection signal is sequentially transmitted to the first detection electrode, and a plurality of crossing the first detection electrode that transmits the second AC detection signal via the capacitance between the first detection electrode and the second detection electrode. The reception level of the second AC detection signal appearing on each second detection electrode is detected, and the input operation is performed from the crossing position on the insulating substrate of the first detection electrode and the second detection electrode where the input operation body approaches and the reception level changes. The input operation position of the input operation body on the surface is detected.
The capacitance between the detection electrode and the input operation body is Cm, the distance between the detection electrode and the input operation body is d, the output level of the first AC detection signal is Vs, and k is a constant. The reception level Vi that appears is expressed by Vi = Vs / (d · k), and is inversely proportional to the distance d between the detection electrode and the input operating body. Therefore, from the reception level Vi of the first AC detection signal detected by the first detection electrode wired along the first direction, the distance between the first detection electrode and the input operation body in the direction orthogonal to the first direction is The distance between the second detection electrode and the input operation body in the direction orthogonal to the second direction is obtained from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction. The two-dimensional input operation position along the input operation surface can be detected.
If the input operation position is a single input operation body until the detected input operation position reaches the input operation surface, the input operation position is detected from the reception level Vi of the first AC detection signal by the same method. Since the reciprocal of the reception level Vi detected for each detection electrode is linear with the distance d between the detection electrode and the input operation body, the input operation position of the input operation body can be accurately detected from the reception level Vi, and the first detection A two-dimensional input operation position on the input operation surface can be detected by simply detecting the reception level Vi for the total number of electrodes and the second detection electrodes.
When the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the first detection electrode and the second detection electrode are changed at each intersection position on the insulating substrate. (2) Since the reception level of the AC detection signal is detected and the input operation position of the input operation body on the input operation surface is detected from the crossing position where the reception level changes, there is no problem of ghosting even if there is a multi-touch operation. Each input operation position can be accurately detected. Even if multiple input operation bodies are separated from the input operation surface, it can be determined as a multi-touch operation, and before touching the input operation surface, switching to a different input operation position detection method can be performed at high speed. Each input operation position can be detected.
検出電極と入力操作体間の静電容量をCm、検出電極と入力操作体間の距離をd、第1交流検出信号の出力レベルをVs、kを定数として、第1検出回路の検出電極に表れる受信レベルViは、Vi=Vs/(d・k)で表され、検出電極と入力操作体間の距離dに反比例する。従って、第1検出回路は、第1方向に沿って配線される第1検出電極が検出した第1交流検出信号の受信レベルViから、第1方向に直交する方向の第1検出電極と入力操作体間の距離が、第2方向に沿って配線される第2検出電極が検出した第1交流検出信号の受信レベルViから、第2方向に直交する方向の第2検出電極と入力操作体間の距離がそれぞれ得られ、入力操作面に沿った二次元の入力操作位置を検出できる。
判定手段でマルチタッチ操作と判定されない通常の入力操作は、第1検出回路が動作してその入力操作位置を検出する。第1検出回路が各検出電極について検出する受信レベルViの逆数は、検出電極と入力操作体間の距離dと線形性があるので、受信レベルViから入力操作体の入力操作位置を精度良く検出でき、第1検出電極と第2検出電極の総電極数について受信レベルViを検出するだけで入力操作面上の二次元の入力操作位置を検出できる。
第2検出回路は、第2交流検出信号を印加する複数の第1検出電極と第2交流検出信号の受信レベルを検出する複数の第2検出電極の全ての交差位置について、交差位置毎に第2交流検出信号の受信レベルが低下した交差位置で交差する第1検出電極と第2検出電極の配線位置から入力操作面の二次元の入力操作位置を入力操作位置を検出する。第2検出回路によれば、全ての交差位置について入力操作体の接近による第2交流検出信号の受信レベルを検出するので、マルチタッチ操作があってもゴースト発生の問題なく、各入力操作位置を正確に検出できる。
第1検出回路と第2検出回路は、複数の第1検出電極と複数の第2検出電極を兼用するので,構造を大幅に変更することなく、異なる検出方式で入力操作位置を検出できる。
請求項2の静電容量式タッチパネルは、判定手段が、第1検出回路が入力操作面上の入力操作体の入力操作位置を検出する前に、2以上の入力操作体による入力操作位置を検出した場合に、マルチタッチ操作と判定することを特徴とする。
第1検出回路によれば、高精度に入力操作位置を検出できるので、判定手段は、複数の入力操作体が入力操作面から離れていてもマルチタッチ操作と判定することができ、入力操作面をタッチ操作する前に、第2検出回路を起動させて高速にマルチタッチ操作の各入力操作位置を検出できる。
請求項3の静電容量式タッチパネルは、切替制御回路が、判定手段がマルチタッチ操作と判定した場合には、第1検出回路から第2検出回路へ動作を切り替え、第2検出回路が入力操作面上のいずれの入力操作体の入力操作位置も検出しない場合に、第2検出回路から第1検出回路へ動作を切り替えることを特徴とする。
マルチタッチ操作は、第2検出回路が動作して入力操作位置を検出し、マルチタッチ操作の入力操作が終わると第1検出回路が動作するので、入力操作の待機状態では第1検出回路が動作する。
請求項4の静電容量式タッチパネルは、第1検出回路が、更に、一方を接地若しくは定電位とした低圧基準電源線と高圧基準電源線との間に直流電圧を出力する一次直流電源回路と、低圧振動電源線と高圧振動電源線との間から直流電圧を出力する二次直流電源回路と、低圧基準電源線と低圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第1インダクタと、高圧基準電源線と高圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第2インダクタと、二次直流電源回路で動作する第1発信手段と高圧基準電源線及び低圧基準電源線間にそれぞれ接続される第1キャパシタ及び第2キャパシタとを備え、第1検出回路を動作させる間は、第2発信手段の動作を停止し、第1発信手段から、第1キャパシタと第2キャパシタを介して、一次直流電源回路へ第1交流検出信号を出力するとともに、各検出電極を、二次直流電源回路の低圧振動電源線と高圧振動電源線のいずれかに接続して第1交流検出信号の周波数で振動させ、第2検出回路を動作させる間は、第2発信手段から複数の第1検出電極へ順に第2交流検出信号を出力するとともに、第1発信手段の第1キャパシタと第2キャパシタからみた出力インピーダンスを低インピーダンスとして第1発信手段の第1交流検出信号の出力を停止することを特徴とする。
第1検出回路を動作させる間は、一次直流電源回路が、低圧基準電源線と高圧基準電源線の一方は接地若しくは定電位に接続して定電位であるので、二次直流電源回路で動作する第1発信手段から第1キャパシタと第2キャパシタを介して一次直流電源回路に第1交流検出信号が出力すると、二次直流電源回路は、第1交流検出信号の周波数fで相対的に変動する。各検出電極は、二次直流電源回路の低圧振動電源線と高圧振動電源線のいずれかに接続するので、定電位の入力操作体に対して第1交流検出信号の周波数fで相対的に電位を変動する。
第2検出回路を動作させる間は、一次直流電源回路と二次直流電源回路間に、第1インダクタと第1キャパシタ若しくは第2インダクタと第2キャパシタとからローパスフィルタが形成されるので、一次直流電源回路の高周波ノイズが二次直流電源回路に接続する各回路に流れることがなく、また、二次直流電源回路に接続する各回路で発生する高周波ノイズが一次直流電源回路側に流れない。
請求項5の静電容量式タッチパネルの入力操作位置検出方法は、絶縁基板の入力操作面に沿って第1方向に配線される複数の第1検出電極と第1方向と交差する第2方向に配線される複数の第2検出電極の各検出電極に、入力操作体との相対電位が変動する第1交流検出信号を発信し、各検出電極と入力操作体間の静電容量を介して、前記各検出電極に表れる第1交流検出信号の受信レベルを検出し、各検出電極毎に検出した第1交流検出信号の受信レベルをもとにその検出電極と入力操作体間の距離を求め、各検出電極の入力操作体との距離を比較して入力操作体の入力操作位置を検出し、検出した入力操作位置が入力操作面に達するまで、単一の入力操作体による入力操作位置を検出した場合には、その入力操作面上の入力操作体の入力操作位置を検出し、検出した入力操作位置が入力操作面に達する前に、2以上の入力操作体による入力操作位置を検出した場合に、第1交流検出信号の発信を停止するとともに、複数の第1検出電極へ順に第2交流検出信号を発信し、第1検出電極と第2検出電極間の静電容量を介して、第2交流検出信号を発信した第1検出電極に交差する複数の各第2検出電極に表れる第2交流検出信号の受信レベルを検出し、入力操作体が接近し受信レベルが変化する第1検出電極と第2検出電極の絶縁基板上の交差位置から、入力操作面上の入力操作体の入力操作位置を検出することを特徴とする。
検出電極と入力操作体間の静電容量をCm、検出電極と入力操作体間の距離をd、第1交流検出信号の出力レベルをVs、kを定数として、第1検出回路の検出電極に表れる受信レベルViは、Vi=Vs/(d・k)で表され、検出電極と入力操作体間の距離dに反比例する。従って、第1方向に沿って配線される第1検出電極が検出した第1交流検出信号の受信レベルViから、第1方向に直交する方向の第1検出電極と入力操作体間の距離が、第2方向に沿って配線される第2検出電極が検出した第1交流検出信号の受信レベルViから、第2方向に直交する方向の第2検出電極と入力操作体間の距離がそれぞれ得られ、入力操作面に沿った二次元の入力操作位置を検出できる。
検出した入力操作位置が入力操作面に達するまで、単一の入力操作体による入力操作位置である場合には、同じ方法で第1交流検出信号の受信レベルViから入力操作位置を検出する。各検出電極について検出する受信レベルViの逆数は、検出電極と入力操作体間の距離dと線形性があるので、受信レベルViから入力操作体の入力操作位置を精度良く検出でき、第1検出電極と第2検出電極の総電極数について受信レベルViを検出するだけで入力操作面上の二次元の入力操作位置を検出できる。
検出した入力操作位置が入力操作面に達する前に、2以上の入力操作体による入力操作位置を検出した場合には、第1検出電極と第2検出電極の絶縁基板上の交差位置毎に第2交流検出信号の受信レベルを検出し、その受信レベルが変化する交差位置から、入力操作面上の入力操作体の入力操作位置を検出するので、マルチタッチ操作があってもゴースト発生の問題なく、各入力操作位置を正確に検出できる。複数の入力操作体が入力操作面から離れていてもマルチタッチ操作と判定することができ、入力操作面をタッチ操作する前に、異なる入力操作位置の検出方法に切り替えて高速にマルチタッチ操作の各入力操作位置を検出できる。 In order to achieve the above-described object, the capacitive touch panel according to
The capacitance between the detection electrode and the input operation body is Cm, the distance between the detection electrode and the input operation body is d, the output level of the first AC detection signal is Vs, and k is a constant. The reception level Vi that appears is expressed by Vi = Vs / (d · k), and is inversely proportional to the distance d between the detection electrode and the input operating body. Accordingly, the first detection circuit performs the input operation with the first detection electrode in the direction orthogonal to the first direction from the reception level Vi of the first AC detection signal detected by the first detection electrode wired along the first direction. The distance between the bodies is between the second detection electrode and the input operation body in the direction orthogonal to the second direction from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction. Are obtained, and a two-dimensional input operation position along the input operation surface can be detected.
For a normal input operation that is not determined to be a multi-touch operation by the determination means, the first detection circuit operates to detect the input operation position. Since the reciprocal of the reception level Vi detected for each detection electrode by the first detection circuit is linear with the distance d between the detection electrode and the input operation body, the input operation position of the input operation body is accurately detected from the reception level Vi. It is possible to detect a two-dimensional input operation position on the input operation surface only by detecting the reception level Vi for the total number of first detection electrodes and second detection electrodes.
The second detection circuit includes a first detection electrode that applies the second AC detection signal and a second detection electrode that detects the reception level of the second AC detection signal. (2) The input operation position is detected as a two-dimensional input operation position on the input operation surface from the wiring positions of the first detection electrode and the second detection electrode that intersect at the intersection position where the reception level of the AC detection signal is lowered. According to the second detection circuit, since the reception level of the second AC detection signal due to the approach of the input operation body is detected at all the intersection positions, each input operation position can be determined without causing a ghost even if there is a multi-touch operation. It can be detected accurately.
Since the first detection circuit and the second detection circuit share the plurality of first detection electrodes and the plurality of second detection electrodes, the input operation position can be detected by different detection methods without significantly changing the structure.
In the capacitive touch panel according to claim 2, the determination unit detects an input operation position by two or more input operation bodies before the first detection circuit detects an input operation position of the input operation body on the input operation surface. In this case, it is determined that the operation is a multi-touch operation.
According to the first detection circuit, since the input operation position can be detected with high accuracy, the determination means can determine that the input operation surface is a multi-touch operation even if a plurality of input operation bodies are separated from the input operation surface. Before the touch operation, the second detection circuit can be activated to detect each input operation position of the multi-touch operation at high speed.
In the capacitive touch panel according to
In the multi-touch operation, the second detection circuit operates to detect the input operation position, and when the multi-touch operation input operation ends, the first detection circuit operates. Therefore, the first detection circuit operates in the standby state of the input operation. To do.
The capacitive touch panel according to claim 4, wherein the first detection circuit further includes a primary DC power supply circuit that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line, one of which is grounded or at a constant potential. A secondary DC power supply circuit that outputs a DC voltage from between the low-voltage vibration power supply line and the high-voltage vibration power supply line; and a high impedance for the first AC detection signal that is connected between the low-voltage reference power supply line and the low-voltage vibration power supply line. A first inductor that is connected between the high-voltage reference power supply line and the high-voltage vibration power supply line and that has a high impedance with respect to the first AC detection signal; And a first capacitor and a second capacitor connected between the high-voltage reference power supply line and the low-voltage reference power supply line, respectively, while the first detection circuit is operated, the operation of the second transmission means is stopped and the first transmission is performed. hand From the first capacitor and the second capacitor, the first AC detection signal is output to the primary DC power supply circuit, and each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit. The second AC detection signal is sequentially output from the second transmission means to the plurality of first detection electrodes while the second detection circuit is operated by connecting to the first AC detection signal and vibrating at the frequency of the first AC detection signal. The output impedance viewed from the first capacitor and the second capacitor of the first transmission means is set to a low impedance, and the output of the first AC detection signal of the first transmission means is stopped.
While operating the first detection circuit, the primary DC power supply circuit operates with the secondary DC power supply circuit because one of the low-voltage reference power supply line and the high-voltage reference power supply line is connected to the ground or a constant potential and has a constant potential. When the first AC detection signal is output from the first transmitting means to the primary DC power supply circuit via the first capacitor and the second capacitor, the secondary DC power supply circuit relatively fluctuates at the frequency f of the first AC detection signal. . Since each detection electrode is connected to either the low-voltage vibration power supply line or the high-voltage vibration power supply line of the secondary DC power supply circuit, the potential relative to the constant potential input operation body at the frequency f of the first AC detection signal is relatively high. Fluctuate.
While the second detection circuit is operated, a low-pass filter is formed between the primary DC power supply circuit and the secondary DC power supply circuit from the first inductor and the first capacitor or the second inductor and the second capacitor. The high frequency noise of the power supply circuit does not flow to each circuit connected to the secondary DC power supply circuit, and the high frequency noise generated in each circuit connected to the secondary DC power supply circuit does not flow to the primary DC power supply circuit side.
According to a fifth aspect of the present invention, there is provided a capacitive touch panel input operation position detection method in a second direction intersecting the first direction with a plurality of first detection electrodes wired in the first direction along the input operation surface of the insulating substrate. A first AC detection signal whose relative potential with the input operation body varies is transmitted to each detection electrode of the plurality of second detection electrodes to be wired, and through the capacitance between each detection electrode and the input operation body, Detecting the reception level of the first AC detection signal appearing on each detection electrode, and determining the distance between the detection electrode and the input operating body based on the reception level of the first AC detection signal detected for each detection electrode; The input operation position of the input operation body is detected by comparing the distance between each detection electrode and the input operation body, and the input operation position by a single input operation body is detected until the detected input operation position reaches the input operation surface. Input, the input of the input operation body on the input operation surface When the operation position is detected and the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the transmission of the first AC detection signal is stopped and a plurality of input operation positions are stopped. A second AC detection signal is sequentially transmitted to the first detection electrode, and a plurality of crossing the first detection electrode that transmits the second AC detection signal via the capacitance between the first detection electrode and the second detection electrode. The reception level of the second AC detection signal appearing on each second detection electrode is detected, and the input operation is performed from the crossing position on the insulating substrate of the first detection electrode and the second detection electrode where the input operation body approaches and the reception level changes. The input operation position of the input operation body on the surface is detected.
The capacitance between the detection electrode and the input operation body is Cm, the distance between the detection electrode and the input operation body is d, the output level of the first AC detection signal is Vs, and k is a constant. The reception level Vi that appears is expressed by Vi = Vs / (d · k), and is inversely proportional to the distance d between the detection electrode and the input operating body. Therefore, from the reception level Vi of the first AC detection signal detected by the first detection electrode wired along the first direction, the distance between the first detection electrode and the input operation body in the direction orthogonal to the first direction is The distance between the second detection electrode and the input operation body in the direction orthogonal to the second direction is obtained from the reception level Vi of the first AC detection signal detected by the second detection electrode wired along the second direction. The two-dimensional input operation position along the input operation surface can be detected.
If the input operation position is a single input operation body until the detected input operation position reaches the input operation surface, the input operation position is detected from the reception level Vi of the first AC detection signal by the same method. Since the reciprocal of the reception level Vi detected for each detection electrode is linear with the distance d between the detection electrode and the input operation body, the input operation position of the input operation body can be accurately detected from the reception level Vi, and the first detection A two-dimensional input operation position on the input operation surface can be detected by simply detecting the reception level Vi for the total number of electrodes and the second detection electrodes.
When the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the first detection electrode and the second detection electrode are changed at each intersection position on the insulating substrate. (2) Since the reception level of the AC detection signal is detected and the input operation position of the input operation body on the input operation surface is detected from the crossing position where the reception level changes, there is no problem of ghosting even if there is a multi-touch operation. Each input operation position can be accurately detected. Even if multiple input operation bodies are separated from the input operation surface, it can be determined as a multi-touch operation, and before touching the input operation surface, switching to a different input operation position detection method can be performed at high speed. Each input operation position can be detected.
請求項1の発明によれば、マルチタッチ操作ではない通常の入力操作の入力操作位置を高速に、かつ高精度に検出することができる。
マルチタッチ操作を検出した場合には、第2検出回路を動作させて、ゴースト発生の問題がない相互容量方式で入力操作位置を検出するので、マルチタッチ操作であっても各入力操作位置を正確に検出できる。
また、第1検出回路と第2検出回路による異なる入力操作位置の検出方式に、共通の第1検出電極と第2検出電極を用いるので、大幅に構造を変更することなく、第1検出回路と第2検出回路の動作を切り替える静電容量式タッチパネルとすることができる。
請求項2の発明によれば、入力操作体が入力操作面に触れる前にマルチタッチ操作を検出し、ゴースト発生の問題がない相互容量方式に切り替えることができる。
請求項3の発明よれば、マルチタッチ操作は、第2検出回路が動作して入力操作位置を検出するので、ゴースト発生の問題がなく、各入力操作位置が検出される。入力操作を待機している状態では、第1検出回路が動作するので、入力操作体が入力操作面から離れたホバー操作の入力操作位置を検出できる。
請求項4の発明によれば、第1検出回路を動作させて入力操作位置を検出する際に、入力操作体側に第1発信手段を設けることなく、受信レベルを検出する検出電極毎に第1交流検出信号を出力させる必要もない。従って、各検出電極の受信レベルを検出する走査のみで二次元の入力操作位置を検出できるので、検出周期を更に短縮させることができる。
また、第1検出回路を動作して各検出電極と入力操作体との電位を変動させる第1インダクタと第1キャパシタ若しくは第2インダクタと第2キャパシタとを利用して、一次直流電源回路と二次直流電源回路間の高周波ノイズを遮断するローパスフィルタを形成できる。
請求項5の発明よれば、マルチタッチ操作ではない単一の入力操作体による入力操作の入力操作位置を高速に、かつ高精度に検出することができる。
マルチタッチ操作を検出した場合には、検出電極の交差位置毎に受信レベルを検出するので、ゴースト発生の問題がなくマルチタッチ操作の各入力操作位置を正確に検出できる。
また、入力操作体が入力操作面に触れる前にマルチタッチ操作を検出し、ゴースト発生の問題がない入力操作位置の検出方法に速やかに切り替えることができる。 According to invention ofClaim 1, the input operation position of normal input operation which is not multi-touch operation can be detected at high speed and with high precision.
When a multi-touch operation is detected, the second detection circuit is operated to detect the input operation position using a mutual capacitance method that does not cause ghosting. Can be detected.
In addition, since the common first detection electrode and second detection electrode are used for the detection method of different input operation positions by the first detection circuit and the second detection circuit, the first detection circuit and the first detection circuit can be used without significantly changing the structure. It can be set as the electrostatic capacitance type touch panel which switches operation | movement of a 2nd detection circuit.
According to the second aspect of the present invention, it is possible to detect the multi-touch operation before the input operation body touches the input operation surface, and to switch to the mutual capacitance method that does not cause a ghost problem.
According to the invention ofclaim 3, in the multi-touch operation, since the second detection circuit operates to detect the input operation position, each input operation position is detected without the problem of ghosting. In the state of waiting for the input operation, the first detection circuit operates, so that the input operation position of the hover operation where the input operation body is separated from the input operation surface can be detected.
According to the invention of claim 4, when the input operation position is detected by operating the first detection circuit, the first transmission means is not provided on the input operation body side, and the first detection electrode for detecting the reception level is provided for each detection electrode. There is no need to output an AC detection signal. Accordingly, since the two-dimensional input operation position can be detected only by scanning for detecting the reception level of each detection electrode, the detection cycle can be further shortened.
In addition, the primary DC power supply circuit and the second capacitor are operated by using the first inductor and the first capacitor or the second inductor and the second capacitor that operate the first detection circuit to change the potential of each detection electrode and the input operation body. A low-pass filter that cuts off high-frequency noise between the secondary DC power supply circuits can be formed.
According to the invention ofclaim 5, the input operation position of the input operation by the single input operation body that is not the multi-touch operation can be detected at high speed and with high accuracy.
When a multi-touch operation is detected, the reception level is detected for each crossing position of the detection electrodes, so that it is possible to accurately detect each input operation position of the multi-touch operation without causing a ghost problem.
In addition, it is possible to detect a multi-touch operation before the input operation body touches the input operation surface, and to quickly switch to an input operation position detection method that does not cause a ghosting problem.
マルチタッチ操作を検出した場合には、第2検出回路を動作させて、ゴースト発生の問題がない相互容量方式で入力操作位置を検出するので、マルチタッチ操作であっても各入力操作位置を正確に検出できる。
また、第1検出回路と第2検出回路による異なる入力操作位置の検出方式に、共通の第1検出電極と第2検出電極を用いるので、大幅に構造を変更することなく、第1検出回路と第2検出回路の動作を切り替える静電容量式タッチパネルとすることができる。
請求項2の発明によれば、入力操作体が入力操作面に触れる前にマルチタッチ操作を検出し、ゴースト発生の問題がない相互容量方式に切り替えることができる。
請求項3の発明よれば、マルチタッチ操作は、第2検出回路が動作して入力操作位置を検出するので、ゴースト発生の問題がなく、各入力操作位置が検出される。入力操作を待機している状態では、第1検出回路が動作するので、入力操作体が入力操作面から離れたホバー操作の入力操作位置を検出できる。
請求項4の発明によれば、第1検出回路を動作させて入力操作位置を検出する際に、入力操作体側に第1発信手段を設けることなく、受信レベルを検出する検出電極毎に第1交流検出信号を出力させる必要もない。従って、各検出電極の受信レベルを検出する走査のみで二次元の入力操作位置を検出できるので、検出周期を更に短縮させることができる。
また、第1検出回路を動作して各検出電極と入力操作体との電位を変動させる第1インダクタと第1キャパシタ若しくは第2インダクタと第2キャパシタとを利用して、一次直流電源回路と二次直流電源回路間の高周波ノイズを遮断するローパスフィルタを形成できる。
請求項5の発明よれば、マルチタッチ操作ではない単一の入力操作体による入力操作の入力操作位置を高速に、かつ高精度に検出することができる。
マルチタッチ操作を検出した場合には、検出電極の交差位置毎に受信レベルを検出するので、ゴースト発生の問題がなくマルチタッチ操作の各入力操作位置を正確に検出できる。
また、入力操作体が入力操作面に触れる前にマルチタッチ操作を検出し、ゴースト発生の問題がない入力操作位置の検出方法に速やかに切り替えることができる。 According to invention of
When a multi-touch operation is detected, the second detection circuit is operated to detect the input operation position using a mutual capacitance method that does not cause ghosting. Can be detected.
In addition, since the common first detection electrode and second detection electrode are used for the detection method of different input operation positions by the first detection circuit and the second detection circuit, the first detection circuit and the first detection circuit can be used without significantly changing the structure. It can be set as the electrostatic capacitance type touch panel which switches operation | movement of a 2nd detection circuit.
According to the second aspect of the present invention, it is possible to detect the multi-touch operation before the input operation body touches the input operation surface, and to switch to the mutual capacitance method that does not cause a ghost problem.
According to the invention of
According to the invention of claim 4, when the input operation position is detected by operating the first detection circuit, the first transmission means is not provided on the input operation body side, and the first detection electrode for detecting the reception level is provided for each detection electrode. There is no need to output an AC detection signal. Accordingly, since the two-dimensional input operation position can be detected only by scanning for detecting the reception level of each detection electrode, the detection cycle can be further shortened.
In addition, the primary DC power supply circuit and the second capacitor are operated by using the first inductor and the first capacitor or the second inductor and the second capacitor that operate the first detection circuit to change the potential of each detection electrode and the input operation body. A low-pass filter that cuts off high-frequency noise between the secondary DC power supply circuits can be formed.
According to the invention of
When a multi-touch operation is detected, the reception level is detected for each crossing position of the detection electrodes, so that it is possible to accurately detect each input operation position of the multi-touch operation without causing a ghost problem.
In addition, it is possible to detect a multi-touch operation before the input operation body touches the input operation surface, and to quickly switch to an input operation position detection method that does not cause a ghosting problem.
図1は、本発明の一実施の形態に係る静電容量式タッチパネル1を示すブロック図である。
図2は、静電容量式タッチパネル1の要部の構成を示すブロック図である。
図3は、第1交流検出信号SGを出力した際の基準電源回路4と振動電源回路3の等価回路図である。
図4は、第1交流検出信号SGの出力レベルVsと検出電極10に表れる受信レベルViの関係を示す等価回路図である。
図5は、静電容量式タッチパネル1の入力操作位置を検出する工程を示すフローチャートである。
図6は、従来の静電容量式タッチパネル100の自己容量方式での動作を説明するブロック図である。
図7は、従来の静電容量式タッチパネル100の相互容量方式での動作を説明するブロック図である。 FIG. 1 is a block diagram showing acapacitive touch panel 1 according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a main part of thecapacitive touch panel 1.
FIG. 3 is an equivalent circuit diagram of the reference power supply circuit 4 and the vibrationpower supply circuit 3 when the first AC detection signal SG is output.
FIG. 4 is an equivalent circuit diagram showing the relationship between the output level Vs of the first AC detection signal SG and the reception level Vi appearing on thedetection electrode 10.
FIG. 5 is a flowchart illustrating a process of detecting an input operation position of thecapacitive touch panel 1.
FIG. 6 is a block diagram for explaining the operation of the conventionalcapacitive touch panel 100 in the self-capacitance method.
FIG. 7 is a block diagram for explaining the operation of the conventionalcapacitive touch panel 100 in the mutual capacitance method.
図2は、静電容量式タッチパネル1の要部の構成を示すブロック図である。
図3は、第1交流検出信号SGを出力した際の基準電源回路4と振動電源回路3の等価回路図である。
図4は、第1交流検出信号SGの出力レベルVsと検出電極10に表れる受信レベルViの関係を示す等価回路図である。
図5は、静電容量式タッチパネル1の入力操作位置を検出する工程を示すフローチャートである。
図6は、従来の静電容量式タッチパネル100の自己容量方式での動作を説明するブロック図である。
図7は、従来の静電容量式タッチパネル100の相互容量方式での動作を説明するブロック図である。 FIG. 1 is a block diagram showing a
FIG. 2 is a block diagram illustrating a configuration of a main part of the
FIG. 3 is an equivalent circuit diagram of the reference power supply circuit 4 and the vibration
FIG. 4 is an equivalent circuit diagram showing the relationship between the output level Vs of the first AC detection signal SG and the reception level Vi appearing on the
FIG. 5 is a flowchart illustrating a process of detecting an input operation position of the
FIG. 6 is a block diagram for explaining the operation of the conventional
FIG. 7 is a block diagram for explaining the operation of the conventional
本発明の一実施の形態に係る静電容量式タッチパネル(以下、タッチパネルという)1の構成を、図1乃至図4を用いて説明する。図1に示すように、タッチパネル1を構成する主要回路部品は、接地電位とした低圧基準電源線GNDと高圧基準電源線VCCからなる基準電源回路4に直流電圧Vccを印加するDC電源16と、低圧基準電源線GNDと高圧基準電源線VCCに接続するコンデンサ17、18等のその他の回路部品からなる非振動回路部品と、接地電位に対して電位が変動する図1で破線で示す振動側回路基板2に搭載される振動回路部品に分けられる。
また、振動側回路基板2には、低圧振動電源線SGNDと高圧振動電源線SVCCとからなる振動電源回路3が配線されている。低圧振動電源線SGNDは低圧基準電源線GNDと、高圧振動電源線SVCCは高圧基準電源線VCCと、それぞれコイル5、6を介して接続している。コイル5とコイル6のインダクタンスは、いずれも後述する固有周波数fの第1交流検出信号SGに対してハイインピーダンスとなる値に設定され、ここでは、同一のインダクタンスLのコイル5、6を用いている。これにより、図1に示すように、基準電源回路4の低圧基準電源線GNDと高圧基準電源線VCCへ、固有周波数fの第1交流検出信号SGを同期させて出力すると、基準電源回路4の低圧基準電源線GNDが接地されて安定した電位にあるので、振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCの電位が、同期して固有周波数fで変動し、両者間の電圧は基準電源回路4と同じ直流出力電圧Vccを維持しながら振動する。
振動電源回路3が配線された振動側回路基板2には、図2に示すように、Y方向に配線された多数のX検出電極10X(10)とX方向に配線された多数のY検出電極10Y(10)とが、ダイオード7を介して振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCのいずれかの、ここでは低圧振動電源線SGNDに接続している。多数のX検出電極10XとY検出電極10Yは、振動側回路基板2若しくは別に設ける絶縁パネルの入力操作面となる表面に沿って互いに絶縁して配置され、操作者が入力操作体である指20を入力操作面に向けて入力操作を行うと、1又は2以上の検出電極10XとY検出電極10Yが指20に対向若しくは接近するように入力操作面の全面に配置されている。
振動側回路基板2には、更に、X検出電極10Xの接続を切り替えるX側アナログマルチプレクサXMUX、Y検出電極10Yの接続を切り替えるY側アナログマルチプレクサYMUX、マルチプレクサMUXの出力側に増幅回路8を介して接続するA/DコンバータADC、図1に示すように第1交流検出信号SGを発信する発信回路11、アナログマルチプレクサの接続を切り替え制御する切り替え制御回路12、X検出電極10Xへ第2交流検出信号SG’を発信する電極駆動回路13、座標演算回路14、インタフェース回路15等を内蔵するCPU9が実装され、いずれも振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCに接続し、DC電源16から出力電圧Vccを受けて動作している。
発信回路11の出力側は、二股に分岐してそれぞれコンデンサ17、18を介して低圧基準電源線GNDと高圧基準電源線VCCに接続している。コンデンサ17とコンデンサ18は、接続する電源線GND、VCCとの直流電圧を遮断する目的で介在させるので、それぞれのキャパシタンスは任意であるが、ここでは、同一のキャパシタンスCのコンデンサ17、18を用いている。
本実施の形態に係るタッチパネル1は、発信回路11から第1交流検出信号SGを発信する第1検出回路と、電極駆動回路13から第2交流検出信号SG’を発信する第2検出回路のいずれかを選択的に動作させ、入力操作体20の入力操作位置を検出する。
(第1検出回路の動作)
第1検出回路を動作させる場合には、振動電源回路3側の発信回路11から第1交流検出信号SGを二股に分岐するコンデンサ17、18を介して基準電源回路4の低圧基準電源線GNDと高圧基準電源線VCCに出力する。固有周波数fの固有発振信号SGが基準電源回路4と振動電源回路7に流れる場合に、低圧基準電源線GNDと高圧基準電源線VCC間及び低圧振動電源線SGNDと高圧振動電源線SVCC間が近接して配線され、固有周波数fの帯域でこれらの電源線間は短絡しているとすれば、図1の基準電源回路4と振動電源回路3は、図3の等価回路図で示される。
図3に示すように、振動電源回路3側の発信回路11の出力SGと基準電源回路4間には、並列にキャパシタンスCのコンデンサ17、18が接続されているので、その合成キャパシタンスは、2Cであり、また、基準電源回路4と振動電源回路3間に並列に接続されるコイル5、6の合成インダクタンスは、L/2となる。これらのキャパシタとインダクタは、固有周波数fの第1交流検出信号SGが流れる閉回路において直列に接続され、第1交流検出信号SGの振幅(レベル)をVi、コイル5、6両端の基準電源回路4と振動電源回路3間の電圧をVs、2πfで表される角速度をω(rad/sec)とすれば、
Vs=[ω2LC/(ω2LC−1)]Vi・・・(1)式
で表される。
ここで、図3に示す回路は、ω2LC=1で直列共振し、そのときの周波数f0は、
f0=1/[2π(LC)1/2]・・・(2)式
となる。
つまり、(2)式関係から得られる共振周波数f0を、第1交流検出信号SGの固有周波数fとすれば、第1交流検出信号SGの出力レベルVsに対して、(1)式から理論上振動電源回路3の電位が無限大で振動し、振動電源回路3に接続する検出電極10の電位も無限大に振動させることができる。その結果、検出電極10と指20との静電容量が10pF程度と微小であっても、検出電極10と指20間に発生する電圧が無限大に拡大するので、後述するようにCPU9の座演算回路14に入力される第1交流検出信号SGの受信レベルViは増大し、その検出が容易となる。
実際のタッチパネル1では、基準電源回路4と振動電源回路3のインダクタンス、浮遊容量などの影響から、(2)式から得る周波数f0で共振せず、また、基準電源回路4と振動電源回路3に第1交流検出信号SGが流れる際のエネルギーロス等により、振動電源回路3は、第1交流検出信号SGの出力レベルVsに対して有限倍率に拡大された振幅で電位が振動する。一方、操作者の指20が触れることのある検出電極10に大電圧を加えることはできないので、第1交流検出信号SGの固有周波数fを共振周波数f0を中心にずらしたり、第1交流検出信号SGの振幅を調整して、CPU9の座標演算回路14で入力操作が確実に検出できる範囲で、検出電極10の電圧振動の振幅を制限している。
全ての検出電極10が低圧振動電源線SGNDに接続することによって、その電位は固有周波数fで振動する一方、足下などの一部が接地している操作者の指(入力操作体)20の電位は定電位であるので、指20が接近して指20との静電容量Cfが増大する検出電極10では、検出電極10から指20へ静電容量Cfを介して固有周波数fの電圧信号が出力される。これを、固有周波数fで振動する振動電源回路3からみれば、入力操作により、指20が接近した検出電極10の電位が相対的に固有周波数fで振動することとなり、振動電源回路3で駆動するCPU9において、固有周波数fの電位変動信号、すなわち第1交流検出信号を検出でき、指20が接近する検出電極10で検出する第1交流検出信号の受信レベルViから入力操作を検出できる。
各検出電極10と入力操作体20間の静電容量Cmは、検出電極と入力操作体間の距離をd、真空の誘電率をε0、空気の比誘電率εを約1、入力操作体20と検出電極10の対向面積をsとして、Cm=ε0・εr・s/dで表され、この静電容量Cmの交流検出信号に対するリアクタンスXcは、交流検出信号の固有周波数がfであるので、Xc=1/(2π・f・Cm)から、Xc=d/(ω・ε0・εr・s)で表される。
図4は、入力操作体20と検出電極10間の電位Vsと検出電極10に表れる交流検出信号SGの受信レベルViの関係を表す第1検出回路の等価回路図であり、図中、Vsは、交流検出信号SGの出力レベル、すなわち検出電極10と入力操作体20間の電位、Cpは、検出電極10と低圧振動電源線SGND間の浮遊容量、rpは、検出電極10の内部抵抗値、R4は、出力抵抗の抵抗値である。図中の等価回路図では、
i1=i2+i3 ・・・(3)式
Vs=i1/(jω・Cm)+i2/(jω・Cp) ・・・(4)式
−i2/(jω・Cp)+i3・rp+i3・R4=0 ・・・(5)式
i3・R4=Vi ・・・(6)式
の関係が成り立ち、(3)式乃至(6)式から、
Vi=[jω・Cm/{1/R4+jω(Cm+Cp)(rp/R4+1)}]・Vs ・・・(7)式
の関係が得られる。
内部抵抗rpを0とし、R4がマルチプレクサMUXを介して後段の積分用オペアンプ8に接続されるので無限大とすれば、(7)式は、
Vi=Cm/(Cp+Cm)・Vs
と置き換えられ、更に
数10pFの浮遊容量Cpに比べて静電容量Cmは数10fFと極めて小さいので、(7)式は、更に
Vi=(Cm/Cp)・Vs ・・・(8)式
で表される。
上述の通り、入力操作体20と検出電極10のCmは、Cm=ε0・εr・s/dで表されるので、これを(8)式に代入して変形すれば、
Vi={ε0・εr・s/(d・Cp)}Vs ・・・(9)式
となり、入力操作中に指20と検出電極10との対向面積sがほぼ変化しないものとして、(9)式中の(ε0・εr・s/Cp)は、定数であるので、これを1/kとおけば、検出電極10に表れる第1交流検出信号SGの受信レベルViは、
Vi=Vs/(d・k) ・・・(10)式
で表され、指20との距離dが近い検出電極10ほど、受信レベルViが第1交流検出信号SGの出力レベルVsに近づく大きな値となる。ただし、指20が検出電極10に近接し、その間の静電容量Cmが数10pFの浮遊容量Cpに比べて無視できない程度に大きくなった場合には(10)式を適用できず、受信レベルViは最大で出力レベルVsとなる。
(10)式を用いれば、複数の各検出電極10に表れる第1交流検出信号の受信レベルViから、各検出電極10と指20の間の距離dを直接求めることができ、本実施の形態では、マルチプレクサMUXで切り替える全ての検出電極10(X検出電極10X、Y検出電極10Y)の配置位置と、各検出電極10から検出する受信レベルViとから、入力操作面に平行なXY方向の入力操作位置(x、y)と入力操作面に直交するZ方向の入力操作位置zの3次元の入力操作位置を検出する。
この入力操作位置(x、y、z)を検出するために、CPU9の切り替え制御回路12は、X側アナログマルチプレクサXMUXとY側アナログマルチプレクサYMUXを切り替え制御し、一走査周期で全てのX検出電極10XとY検出電極10Yを各検出電極10毎に順に積分用オペアンプからなる増幅回路8へ接続する。これにより、全ての検出電極10に表れる第1交流検出信号の受信レベルViは、増幅回路8で増幅された後、A/DコンバータADCに入力される。
A/DコンバータADCは、第1交流検出信号SGの固有周波数fの少なくとも2倍以上の周波数でサンプリングし、第1交流検出信号SGの受信レベルViを量子化してCPU9の座標演算回路14へ出力する。
A/Dコンバータ14から出力される量子化データは、その時にアナログマルチプレクサMUXが選択接続した検出電極10に表れる第1交流検出信号SGの受信レベルViを表すので、入力操作位置を検出する座標演算回路14では、その検出電極10が増幅回路8に接続する接続期間中にA/DコンバータADCから入力された量子化データの総和を所定の閾値と比較し、所定の閾値以上である場合に入力操作体20が接近した検出電極10と判定する。判定された検出電極10から検出した第1交流検出信号SGの受信レベルViを用いて、(10)式からその検出電極10の配置位置と入力操作体20との距離dが得られるので、同様に判定された複数の各検出電極10の入力操作面上のX方向若しくはY方向の配設位置と受信レベルViとから入力操作面上の二次元の入力操作位置及び/又は入力操作面上のZ方向の高さを含む三次元の入力操作位置を検出する。
CPU9は、座標演算回路14が一走査周期中に、入力操作位置が入力操作面上にあるか否かにかかわらず、複数の入力操作位置を検出した場合には、発信回路11からの第1交流検出信号SGを発信を停止して、第1検出回路から相互容量方式で入力操作位置を検出する第2検出回路に動作を切り替える。一方、複数の入力操作位置を検出しない限り、単一の入力操作体20による入力操作であるとして、座標演算回路14が検出した二次元若しくは三次元の入力操作位置を、インターフェース回路15から直流が絶縁された信号線19を介して、USB通信、I2C通信等で入力操作位置を利用する上位機器に出力される。
この第1検出回路では、いずれかの検出電極10と入力操作体20との距離dが、その検出電極10で検出した第1交流検出信号SGの受信レベルViの逆数に比例する((10)式参照)ので、XY方向で交差配置されるX検出電極10XとY検出電極10Yで検出する受信レベルViから、入力操作面上のZ方向の高さを含む三次元の入力操作位置を精度良く検出できる。
また、一走査周期に、検出電極10(X検出電極10XとY検出電極10Y)の配線数に相当する走査で各検出電極10の受信レベルViを検出するだけで、入力操作面上の二次元の入力操作位置を検出できるので、検出電極の全ての交点について走査する相互容量方式に比べて高速にかつ低消費電力で入力操作位置を検出できる。
(第2検出回路の動作)
第2検出回路を動作させる場合には、発信回路11からの第1交流検出信号SGの発信を停止し、CPU9に内蔵の第2発信手段となる電極駆動回路13から第2交流検出信号SG’を発信し、相互容量方式で入力操作体20の二次元の入力操作位置を検出する。
第1交流検出信号SGの発信が停止することにより、振動電源回路3の電位振動も停止するが、振動側回路基板2に搭載された各回路部品は、コイル5、6を介したDC電源16の電源で動作する。第2検出回路では、複数のX検出電極10X若しくは複数のY検出電極10Yの一方を第2交流検出信号SG’を印加する駆動電極D(n)、他方を第2交流検出信号SG’の受信レベルViを検出する検出電極S(m)とし、入力操作面上の全ての駆動電極D(n)と検出電極S(m)の交点(n、m)について第2交流検出信号SG’の受信レベルViを検出する。
特定の交点(n、m)に入力操作体20が接近すると、その交点(n、m)の駆動電極D(n)に第2交流検出信号SG’を印加しているタイミングで、交点(n、m)の検出電極S(m)に表れる受信レベルViは、第2交流検出信号SG’の一部が入力操作体20に流れて減少するので、受信レベルViが所定の閾値未満となる全ての交点(n、m)で交差する駆動電極D(n)と検出電極S(m)のXY方向の配線位置から入力操作体20の二次元の入力操作位置を検出する。
本実施の形態では、複数のX検出電極10Xを駆動電極D(n)として、切り替え制御回路12は、X側アナログマルチプレクサXMUXを切り替え制御して、電極駆動回路13を各X検出電極10Xに切り替え接続し、各X検出電極10Xへ順に第2交流検出信号SG’を印加する。第2交流検出信号SG’の出力レベルVsや交流周波数は任意であるが、ここでは受信レベルViの検出に第1検出回路の検出回路を共用するので、第1交流検出信号SGの出力レベルVs及び周波数fと同一とする。しかしながら、第1交流検出信号SGと第2交流検出信号SG’の出力レベルVsを必ずしも一致させる必要はないので、電極駆動回路13を発信回路11で代用し、第1交流検出信号SGを第2交流検出信号SG’として各X検出電極10Xへ印加させてもよい。
いずれかのX検出電極10X(駆動電極D(n))に第2交流検出信号SG’を印加している間、切り替え制御回路12はY側アナログマルチプレクサYMUXを切り替え制御して、その駆動電極D(n)に絶縁して交差する全てのY検出電極10Yを順に増幅回路8へ接続し、第2交流検出信号SG’の受信レベルViを検出する検出電極S(m)とする。これにより、全ての交点(n、m)について、検出電極S(m)に表れる第2交流検出信号SG’受信レベルViは、増幅回路8で増幅された後、A/DコンバータADCに入力され、A/DコンバータADCは、第2交流検出信号SG’の固有周波数fの少なくとも2倍以上の周波数でサンプリングし、第2交流検出信号SG’の受信レベルViを量子化してCPU9の座標演算回路14へ出力する。
CPU9の切り替え制御回路12は、一走査期間中に同様の切り替え制御を繰り返し、全てのX検出電極10XとY検出電極10Yの交点(n、m)について検出された受信レベルViを順に座標演算回路14へ出力する。
ここで、各交点(n、m)について検出された受信レベルViは、交点(n、m)で交差する駆動電極D(n)と検出電極S(m)間の相互容量の変化量を表し、入力操作体20と交点(n、m)との距離が接近するほど低下する。そこで、座標演算回路14は、全ての交点(n、m)について検出された受信レベルViを、X検出電極10Xの配置順であるX方向と、Y検出電極10Yの配置順であるY方向に沿って比較し、極小値が検出された交点(n、m)の近傍に入力操作があったとものとし、その交点(n、m)を含む周囲の交点(n、m)について検出された受信レベルViのXY方向の重心からXY方向の二次元の入力操作位置を検出する。
この第2検出回路では、2本の指20を同時に入力操作面に触れて入力操作を行ういわゆるマルチタッチ操作であっても、全ての交点(n、m)について受信レベルViを検出するので、指20の入力操作により受信レベルViが極小値となる交点(n、m)のみを検出することができ、ゴースト発生の問題がなく、複数の二次元の各入力操作位置を正確に検出できる。
CPU9は、第2検出回路を動作させて検出した複数の入力操作位置についても、インターフェース回路15から直流が絶縁された信号線19を介して、USB通信、I2C通信等で入力操作位置を利用する上位機器に出力する。
第2検出回路が動作している間に、発信回路11は第1交流検出信号SGの発信を停止し、コンデンサ17、18側からみた発信回路11の出力インピーダンスを低インピーダンスとしている。従って、振動電源回路3と基準電源回路4の間には、コイル5、6とコンデンサ17、18からなるローパスフィルタが形成され、DC電源16側と振動側回路基板2に実装された各回路部品との間で互いに相手側に高周波ノイズが伝達されない。
以下、このように構成された静電容量式タッチパネル1の動作を、図5のフローチャートで説明する。入力操作が行われていない待機状態では、第1検出回路が動作している(ステップS1)。第1検出回路の動作では、振動電源回路3の電位を振動させるだけで、高圧振動電源線SVCCと低圧振動電源線SGND間や高圧基準電源線VCCと低圧基準電源線GND間に電流が流れないので、極めて少ない消費電力で入力操作を検出できる。
特定の検出電極10について検出した受信レベルViを表す量子化データの総和が所定の閾値以上となった場合には、入力操作面に接近する入力操作があったものと推測して、一走査期間中に量子化データの総和が所定の閾値を超えた複数の検出電極10の受信レベルViから二次元若しくは入力操作面から離れたZ方向を含む三次元の入力操作位置を検出する(ステップS2)。
ステップS2の一走査期間中に、量子化データの総和が所定の閾値を超える検出電極10が1未満である場合には、入力操作の誤検出若しくは入力操作が終了したものとして、入力操作の待機状態(ステップS1)に戻る。
続いて、ステップS2で検出した入力操作位置が1カ所であるか複数箇所であるかを判定し(ステップS3)、複数の入力操作位置が検出された場合には、複数の指(入力操作体)20を入力操作面に接触させるマルチタップ操作が試みられていると推測して第2検出回路を起動し(ステップS4)、単一の入力操作位置である場合には、その検出した入力操作位置を上位装置へ出力した後(ステップS5)、ステップS2に戻り、第1検出回路を動作させた入力操作位置の検出を繰り返す。
つまり、第1検出回路を動作させて入力操作位置を検出するステップS2では、入力操作体20を入力操作面から離れた状態のまま操作するいわゆるホバー操作であっても、入力操作位置を検出することができ、マルチタッチ操作をホバー操作の段階で検出し、入力操作体20が入力操作面に接触する前に第2検出回路を起動させることができる。一方、マルチタッチ操作が検出されない限り、入力操作体20が入力操作面に接触した後も第1検出回路が動作して入力操作位置を検出するので、高速にかつ高精度に2次元の入力操作位置を検出できる。
ステップS4で第2検出回路を起動させた場合には、第2検出回路で所定時間内に1又は2以上の入力操作位置を検出したかどうかを判定し(ステップS6)、複数の走査周期を繰り返す所定時間内に入力操作位置が検出されなかった場合には、入力操作が終了したとして入力操作の待機状態(ステップS1)に戻る。ここで、所定時間は、第1検出回路でホバー操作が検出されてから入力操作面に触れるまでの操作時間よりわずかに長い時間に設定する。これにより、入力操作体20が、第2検出回路で検出可能な入力操作面に達する前の入力操作位置にあっても、入力操作が終了したものと誤判定されることがない。
第2検出回路で1又は2以上の入力操作位置を検出した場合には、その検出数にかかわらず、全ての検出した入力操作位置を上位装置へ出力した後(ステップS7)、ステップS6に戻り、第2検出回路を動作させた入力操作位置の検出を繰り返す。
本実施の形態によれば、マルチタッチ操作を意図した複数の入力操作体20が入力操作面に接触する前に、ゴースト問題が発生しない相互容量方式の第2検出回路を起動させるので、検出方式の切り替えによる時間の遅れがなく、すみやかに二次元の入力操作位置を検出できる。
また、本実施の形態によれば、2種類の検出方式の第1検出回路と第2検出回路で入力操作面に沿って配線された同一の検出電極10を兼用するとともに、各検出電極10に表れる受信レベルViの検出手段として、Y側アナログマルチプレクサYMUX、増幅回路8、A/DコンバータADC、切り替え制御回路12等の回路を兼用するので、大幅な構造変更や回路部品を追加することなく、第1検出回路と第2検出回路を選択的に動作させることができる。
更に、本実施の形態によれば、第1検出回路により入力操作位置を検出する際に、全ての検出電極10を振動電源回路3に接続して、一括して入力操作体20に対し第1交流検出信号SGの出力レベルVsで振動させるので、受信レベルViを検出する検出電極10毎に第1交流検出信号SGを印加する駆動制御の必要がなく、一走査周期が短縮し、より高速に入力操作位置を検出できる。しかしながら、検出電極10と入力操作体20の間に相対電位が変動する第1交流検出信号SGを発生させるものであれば、受信レベルViを検出する検出電極10毎に第1交流検出信号SGを印加してもよく、又、入力操作体20側を第1交流検出信号SGで電位変動させてもよい。
また、上述の実施の形態では、マルチタッチ操作ではない通常の入力操作の入力操作位置は、第1検出回路を動作させて検出しているが、入力操作体20が入力操作面に接触する入力操作操作位置は、マルチタッチ操作であるかにかかわらず、第2検出回路を動作させて検出してもよい。 A configuration of a capacitive touch panel (hereinafter referred to as a touch panel) 1 according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, main circuit components constituting thetouch panel 1 include a DC power supply 16 that applies a DC voltage Vcc to a reference power supply circuit 4 including a low-voltage reference power supply line GND and a high-voltage reference power supply line VCC that are ground potentials; Non-vibration circuit components composed of other circuit components such as capacitors 17 and 18 connected to the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC, and the vibration side circuit indicated by the broken line in FIG. It is divided into vibration circuit components mounted on the substrate 2.
The vibration side circuit board 2 is provided with a vibrationpower supply circuit 3 including a low-voltage vibration power supply line SGND and a high-voltage vibration power supply line SVCC. The low-voltage vibration power supply line SGND is connected to the low-voltage reference power supply line GND, and the high-voltage vibration power supply line SVCC is connected to the high-voltage reference power supply line VCC via the coils 5 and 6, respectively. The inductances of the coil 5 and the coil 6 are both set to a value that becomes high impedance with respect to a first AC detection signal SG having a natural frequency f described later. Here, the coils 5 and 6 having the same inductance L are used. Yes. As a result, as shown in FIG. 1, when the first AC detection signal SG having the natural frequency f is synchronously output to the low-voltage reference power supply line GND and the high-voltage reference power supply line VCC of the reference power supply circuit 4, the reference power supply circuit 4 Since the low-voltage reference power line GND is grounded and has a stable potential, the potentials of the low-voltage vibration power line SGND and the high-voltage vibration power line SVCC of the vibration power circuit 3 fluctuate synchronously with the natural frequency f, and the voltage between them Vibrates while maintaining the same DC output voltage Vcc as the reference power supply circuit 4.
As shown in FIG. 2, the vibration circuit board 2 to which the vibrationpower supply circuit 3 is wired has a large number of X detection electrodes 10X (10) wired in the Y direction and a large number of Y detection electrodes wired in the X direction. 10Y (10) is connected to one of the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 3 via the diode 7, here the low-voltage vibration power supply line SGND. A large number of X detection electrodes 10X and Y detection electrodes 10Y are arranged so as to be insulated from each other along a surface serving as an input operation surface of the vibration side circuit board 2 or an insulating panel provided separately, and an operator is a finger 20 as an input operation body. When the input operation is performed toward the input operation surface, one or more detection electrodes 10X and the Y detection electrode 10Y are arranged on the entire input operation surface so as to face or approach the finger 20.
The vibration side circuit board 2 further includes an X side analog multiplexer XMUX for switching the connection of theX detection electrode 10X, a Y side analog multiplexer YMUX for switching the connection of the Y detection electrode 10Y, and an output side of the multiplexer MUX via the amplifier circuit 8. The A / D converter ADC to be connected, the transmission circuit 11 for transmitting the first AC detection signal SG as shown in FIG. 1, the switching control circuit 12 for switching control of the connection of the analog multiplexer, and the second AC detection signal to the X detection electrode 10X. A CPU 9 including an electrode drive circuit 13 for transmitting SG ′, a coordinate calculation circuit 14, an interface circuit 15 and the like is mounted, all of which are connected to the low-voltage vibration power supply line SGND and the high-voltage vibration power supply line SVCC of the vibration power supply circuit 3, It operates by receiving the output voltage Vcc from the power supply 16.
The output side of thetransmission circuit 11 is bifurcated and connected to the low-voltage reference power line GND and the high-voltage reference power line VCC via capacitors 17 and 18 respectively. Since the capacitor 17 and the capacitor 18 are interposed for the purpose of cutting off the DC voltage between the power supply lines GND and VCC to be connected, the respective capacitances are arbitrary, but here, the capacitors 17 and 18 having the same capacitance C are used. ing.
Touch panel 1 according to the present embodiment includes any one of a first detection circuit that transmits first AC detection signal SG from transmission circuit 11 and a second detection circuit that transmits second AC detection signal SG ′ from electrode drive circuit 13. Are selectively operated, and the input operation position of the input operation body 20 is detected.
(Operation of the first detection circuit)
When operating the first detection circuit, the low-voltage reference power line GND of the reference power circuit 4 is connected to the first AC detection signal SG from theoscillation circuit 11 on the vibration power circuit 3 side via the capacitors 17 and 18 that bifurcate. Output to the high-voltage reference power line VCC. When the natural oscillation signal SG having the natural frequency f flows in the reference power supply circuit 4 and the vibration power supply circuit 7, the low voltage reference power supply line GND and the high voltage reference power supply line VCC and the low voltage vibration power supply line SGND and the high voltage vibration power supply line SVCC are close to each other. If the power supply lines are short-circuited in the band of the natural frequency f, the reference power supply circuit 4 and the vibration power supply circuit 3 of FIG. 1 are shown in the equivalent circuit diagram of FIG.
As shown in FIG. 3, since capacitors 17 and 18 having a capacitance C are connected in parallel between the output SG of the transmission circuit 11 on the vibration power supply circuit 3 side and the reference power supply circuit 4, the combined capacitance is 2C. In addition, the combined inductance of the coils 5 and 6 connected in parallel between the reference power supply circuit 4 and the vibration power supply circuit 3 is L / 2. These capacitors and inductors are connected in series in a closed circuit through which the first AC detection signal SG having the natural frequency f flows. The amplitude (level) of the first AC detection signal SG is Vi, and the reference power supply circuits at both ends of the coils 5 and 6 are connected. 4 and the voltage between the vibration power supply circuit 3 is Vs, and the angular velocity represented by 2πf is ω (rad / sec),
Vs = [ω 2 LC / (ω 2 LC-1)] Vi (1).
Here, the circuit shown in FIG. 3 resonates in series at ω 2 LC = 1, and the frequency f 0 at that time is
f 0 = 1 / [2π (LC) 1/2 ] (2).
That is, if the resonance frequency f 0 obtained from the relationship of the expression (2) is the natural frequency f of the first AC detection signal SG, the theory from the expression (1) is obtained with respect to the output level Vs of the first AC detection signal SG. The potential of the upper vibrationpower supply circuit 3 vibrates at infinity, and the potential of the detection electrode 10 connected to the vibration power supply circuit 3 can also be vibrated to infinity. As a result, even if the capacitance between the detection electrode 10 and the finger 20 is as small as about 10 pF, the voltage generated between the detection electrode 10 and the finger 20 expands infinitely. The reception level Vi of the first AC detection signal SG input to the arithmetic circuit 14 increases, and the detection becomes easy.
Theactual touch panel 1 does not resonate at the frequency f 0 obtained from the equation (2) due to the influence of the inductance and stray capacitance of the reference power supply circuit 4 and the vibration power supply circuit 3, and the reference power supply circuit 4 and the vibration power supply circuit 3 Due to an energy loss or the like when the first AC detection signal SG flows, the vibration power supply circuit 3 vibrates with an amplitude expanded to a finite magnification with respect to the output level Vs of the first AC detection signal SG. On the other hand, since a large voltage cannot be applied to the detection electrode 10 that the operator's finger 20 may touch, the natural frequency f of the first AC detection signal SG is shifted around the resonance frequency f 0 or the first AC detection is performed. By adjusting the amplitude of the signal SG, the amplitude of the voltage oscillation of the detection electrode 10 is limited within a range in which the input operation can be reliably detected by the coordinate calculation circuit 14 of the CPU 9.
When all thedetection electrodes 10 are connected to the low-voltage vibration power supply line SGND, the potential vibrates at the natural frequency f, while the potential of the operator's finger (input operation body) 20 whose part such as a foot is grounded. Is a constant potential, in the detection electrode 10 where the finger 20 approaches and the electrostatic capacitance Cf with the finger 20 increases, a voltage signal of the natural frequency f is transmitted from the detection electrode 10 to the finger 20 via the electrostatic capacitance Cf. Is output. If this is viewed from the vibration power supply circuit 3 that vibrates at the natural frequency f, the input operation causes the potential of the detection electrode 10 that the finger 20 has approached to vibrate relatively at the natural frequency f, and is driven by the vibration power supply circuit 3. The CPU 9 can detect the potential fluctuation signal of the natural frequency f, that is, the first AC detection signal, and can detect the input operation from the reception level Vi of the first AC detection signal detected by the detection electrode 10 that the finger 20 approaches.
The electrostatic capacitance Cm between eachdetection electrode 10 and the input operation body 20 is the distance between the detection electrode and the input operation body d, the dielectric constant of vacuum ε0, the relative dielectric constant ε of air is about 1, and the input operation body 20 And the detection electrode 10 is represented by Cm = ε0 · εr · s / d, and the reactance Xc of the capacitance Cm with respect to the AC detection signal is f because the natural frequency of the AC detection signal is f. From Xc = 1 / (2π · f · Cm), Xc = d / (ω · ε0 · εr · s).
FIG. 4 is an equivalent circuit diagram of the first detection circuit showing the relationship between the potential Vs between theinput operating body 20 and the detection electrode 10 and the reception level Vi of the AC detection signal SG appearing on the detection electrode 10. , The output level of the AC detection signal SG, that is, the potential between the detection electrode 10 and the input operating body 20, Cp is the stray capacitance between the detection electrode 10 and the low-voltage vibration power supply line SGND, rp is the internal resistance value of the detection electrode 10, R4 is the resistance value of the output resistance. In the equivalent circuit diagram in the figure,
i1 = i2 + i3 (3) Formula Vs = i1 / (jω · Cm) + i2 / (jω · Cp) (4) Formula −i2 / (jω · Cp) + i3 · rp + i3 · R4 = 0 -(5) Formula i3 * R4 = Vi ... The relationship of Formula (6) is established, and from Formula (3) to Formula (6),
Vi = [jω · Cm / {1 / R4 + jω (Cm + Cp) (rp / R4 + 1)}] · Vs (7) Equation (7) is obtained.
If the internal resistance rp is set to 0, and R4 is connected to the integratingoperational amplifier 8 through the multiplexer MUX, it is assumed that it is infinite.
Vi = Cm / (Cp + Cm) · Vs
Since the electrostatic capacitance Cm is extremely small, such as several tens of fF, compared to the floating capacitance Cp of several tens of pF, the equation (7) is further expressed by the following equation: Vi = (Cm / Cp) · Vs (8) expressed.
As described above, Cm of theinput operating body 20 and the detection electrode 10 is expressed by Cm = ε0 · εr · s / d. Therefore, if this is substituted into the equation (8) and transformed,
Vi = {ε0 · εr · s / (d · Cp)} Vs (9) Assuming that the facing area s between thefinger 20 and the detection electrode 10 does not substantially change during the input operation, (9) Since (ε0 · εr · s / Cp) in the equation is a constant, if this is set to 1 / k, the reception level Vi of the first AC detection signal SG appearing on the detection electrode 10 is
Vi = Vs / (d · k) (Expression (10)), and the detection level of thedetection electrode 10 that is closer to the finger 20 is closer to the output level Vs of the first AC detection signal SG. Value. However, when the finger 20 is close to the detection electrode 10 and the electrostatic capacitance Cm between them is larger than the stray capacitance Cp of several tens of pF, the expression (10) cannot be applied and the reception level Vi. Becomes a maximum output level Vs.
If Expression (10) is used, the distance d between eachdetection electrode 10 and the finger 20 can be directly obtained from the reception level Vi of the first AC detection signal appearing on each of the plurality of detection electrodes 10, and this embodiment Then, the input in the XY directions parallel to the input operation surface is determined from the arrangement positions of all the detection electrodes 10 (X detection electrode 10X, Y detection electrode 10Y) switched by the multiplexer MUX and the reception level Vi detected from each detection electrode 10. A three-dimensional input operation position of the operation position (x, y) and the input operation position z in the Z direction orthogonal to the input operation surface is detected.
In order to detect this input operation position (x, y, z), the switchingcontrol circuit 12 of the CPU 9 switches and controls the X-side analog multiplexer XMUX and the Y-side analog multiplexer YMUX, and all the X detection electrodes in one scanning cycle. The 10X and Y detection electrodes 10Y are connected to the amplification circuit 8 composed of an operational amplifier for integration for each detection electrode 10 in order. As a result, the reception level Vi of the first AC detection signal appearing on all the detection electrodes 10 is amplified by the amplifier circuit 8 and then input to the A / D converter ADC.
The A / D converter ADC samples at a frequency at least twice the natural frequency f of the first AC detection signal SG, quantizes the reception level Vi of the first AC detection signal SG, and outputs it to the coordinatecalculation circuit 14 of the CPU 9. To do.
Since the quantized data output from the A /D converter 14 represents the reception level Vi of the first AC detection signal SG appearing at the detection electrode 10 that is selectively connected by the analog multiplexer MUX at that time, the coordinate calculation for detecting the input operation position In the circuit 14, the total sum of the quantized data input from the A / D converter ADC during the connection period in which the detection electrode 10 is connected to the amplifier circuit 8 is compared with a predetermined threshold, and input when it is equal to or higher than the predetermined threshold. It determines with the detection electrode 10 which the operating body 20 approached. Using the received level Vi of the first AC detection signal SG detected from the determined detection electrode 10, the distance d between the arrangement position of the detection electrode 10 and the input operation body 20 can be obtained from the equation (10). The two-dimensional input operation position on the input operation surface and / or the input operation surface from the arrangement position of the plurality of detection electrodes 10 in the X or Y direction on the input operation surface and the reception level Vi. A three-dimensional input operation position including the height in the Z direction is detected.
When the coordinatecalculation circuit 14 detects a plurality of input operation positions regardless of whether or not the input operation position is on the input operation surface during one scanning cycle, the CPU 9 receives the first signal from the transmission circuit 11. The transmission of the AC detection signal SG is stopped, and the operation is switched from the first detection circuit to the second detection circuit that detects the input operation position by the mutual capacitance method. On the other hand, unless a plurality of input operation positions are detected, it is assumed that the input operation is performed by the single input operation body 20, and the two-dimensional or three-dimensional input operation position detected by the coordinate calculation circuit 14 is supplied from the interface circuit 15 as a direct current. The signal is output to a host device that uses the input operation position by USB communication, I 2 C communication, or the like via the insulated signal line 19.
In the first detection circuit, the distance d between any one of thedetection electrodes 10 and the input operating body 20 is proportional to the inverse of the reception level Vi of the first AC detection signal SG detected by the detection electrode 10 ((10)). Therefore, the three-dimensional input operation position including the height in the Z direction on the input operation surface is accurately determined from the reception level Vi detected by the X detection electrode 10X and the Y detection electrode 10Y that are arranged to intersect each other in the XY direction. It can be detected.
Further, only by detecting the reception level Vi of eachdetection electrode 10 by scanning corresponding to the number of wirings of the detection electrodes 10 (X detection electrode 10X and Y detection electrode 10Y) in one scanning cycle, two-dimensional on the input operation surface. Therefore, the input operation position can be detected at high speed and with low power consumption as compared with the mutual capacitance method in which all the intersections of the detection electrodes are scanned.
(Operation of the second detection circuit)
When operating the second detection circuit, the transmission of the first AC detection signal SG from thetransmission circuit 11 is stopped, and the second AC detection signal SG ′ from the electrode driving circuit 13 serving as the second transmission means built in the CPU 9 is stopped. And the two-dimensional input operation position of the input operation body 20 is detected by the mutual capacitance method.
By stopping the transmission of the first AC detection signal SG, the potential vibration of the vibrationpower supply circuit 3 is also stopped, but each circuit component mounted on the vibration side circuit board 2 is connected to the DC power supply 16 via the coils 5 and 6. Operates with a power source. In the second detection circuit, one of the plurality of X detection electrodes 10X or the plurality of Y detection electrodes 10Y receives the drive signal D (n) to which the second AC detection signal SG ′ is applied, and the other receives the second AC detection signal SG ′. The detection electrode S (m) for detecting the level Vi is received, and the second AC detection signal SG ′ is received at the intersections (n, m) of all the drive electrodes D (n) and the detection electrodes S (m) on the input operation surface. Detect level Vi.
When theinput operating body 20 approaches a specific intersection (n, m), at the timing when the second AC detection signal SG ′ is applied to the drive electrode D (n) at the intersection (n, m), the intersection (n M), the reception level Vi appearing on the detection electrode S (m) decreases because a part of the second AC detection signal SG ′ flows to the input operation body 20 and decreases. The two-dimensional input operation position of the input operation body 20 is detected from the wiring positions in the XY directions of the drive electrode D (n) and the detection electrode S (m) that intersect at the intersection (n, m).
In the present embodiment, the switchingcontrol circuit 12 switches the X-side analog multiplexer XMUX to switch the electrode driving circuit 13 to each X detection electrode 10X by using the plurality of X detection electrodes 10X as the drive electrodes D (n). The second AC detection signal SG ′ is applied in order to each X detection electrode 10X. The output level Vs and the AC frequency of the second AC detection signal SG ′ are arbitrary, but here the detection circuit of the first detection circuit is shared for detection of the reception level Vi, and therefore the output level Vs of the first AC detection signal SG. And the frequency f. However, since the output levels Vs of the first AC detection signal SG and the second AC detection signal SG ′ do not necessarily coincide with each other, the electrode drive circuit 13 is replaced by the transmission circuit 11 and the first AC detection signal SG is changed to the second AC detection signal SG. You may make it apply to each X detection electrode 10X as alternating current detection signal SG '.
While the second AC detection signal SG ′ is applied to any one of theX detection electrodes 10X (drive electrode D (n)), the switching control circuit 12 switches and controls the Y-side analog multiplexer YMUX, and the drive electrode D All the Y detection electrodes 10Y insulated and intersecting with (n) are connected in order to the amplifier circuit 8, and set as a detection electrode S (m) for detecting the reception level Vi of the second AC detection signal SG ′. As a result, the second AC detection signal SG ′ reception level Vi appearing at the detection electrode S (m) at all the intersections (n, m) is amplified by the amplifier circuit 8 and then input to the A / D converter ADC. The A / D converter ADC samples at a frequency that is at least twice the natural frequency f of the second AC detection signal SG ′, quantizes the reception level Vi of the second AC detection signal SG ′, and coordinates the CPU 9. 14 to output.
The switchingcontrol circuit 12 of the CPU 9 repeats the same switching control during one scanning period, and sequentially receives the reception levels Vi detected at the intersections (n, m) of all the X detection electrodes 10X and the Y detection electrodes 10Y. 14 to output.
Here, the reception level Vi detected at each intersection (n, m) represents the amount of change in mutual capacitance between the drive electrode D (n) and the detection electrode S (m) that intersect at the intersection (n, m). As the distance between theinput operation body 20 and the intersection (n, m) approaches, it decreases. Therefore, the coordinate calculation circuit 14 sets the reception levels Vi detected for all the intersections (n, m) in the X direction that is the arrangement order of the X detection electrodes 10X and the Y direction that is the arrangement order of the Y detection electrodes 10Y. And an input operation is performed in the vicinity of the intersection (n, m) where the minimum value is detected, and reception is detected for the surrounding intersection (n, m) including the intersection (n, m). A two-dimensional input operation position in the XY direction is detected from the center of gravity in the XY direction of the level Vi.
In the second detection circuit, the reception level Vi is detected for all the intersections (n, m) even in the so-called multi-touch operation in which the twofingers 20 are simultaneously touched on the input operation surface to perform the input operation. Only the intersection (n, m) at which the reception level Vi becomes the minimum value by the input operation of the finger 20 can be detected, there is no problem of ghost generation, and a plurality of two-dimensional input operation positions can be detected accurately.
TheCPU 9 also sets the input operation positions for the plurality of input operation positions detected by operating the second detection circuit by USB communication, I 2 C communication or the like via the signal line 19 in which the direct current is insulated from the interface circuit 15. Output to the higher-level device to be used.
While the second detection circuit is operating, thetransmission circuit 11 stops transmitting the first AC detection signal SG, and the output impedance of the transmission circuit 11 viewed from the capacitors 17 and 18 side is set to a low impedance. Therefore, a low-pass filter including coils 5 and 6 and capacitors 17 and 18 is formed between the vibration power supply circuit 3 and the reference power supply circuit 4, and each circuit component mounted on the DC power supply 16 side and the vibration side circuit board 2. High frequency noise is not transmitted to the other party.
Hereinafter, the operation of thecapacitive touch panel 1 configured as described above will be described with reference to the flowchart of FIG. In a standby state where no input operation is performed, the first detection circuit is operating (step S1). In the operation of the first detection circuit, only the potential of the vibration power supply circuit 3 is vibrated, and no current flows between the high-voltage vibration power supply line SVCC and the low-voltage vibration power supply line SGND or between the high-voltage reference power supply line VCC and the low-voltage reference power supply line GND. Therefore, it is possible to detect an input operation with very little power consumption.
When the sum of the quantized data representing the reception level Vi detected for thespecific detection electrode 10 is equal to or greater than a predetermined threshold, it is assumed that there has been an input operation approaching the input operation surface, and one scanning period Two-dimensional or three-dimensional input operation positions including the Z direction away from the input operation surface are detected from the reception levels Vi of the plurality of detection electrodes 10 in which the sum of quantized data exceeds a predetermined threshold value (step S2). .
If the number ofdetection electrodes 10 in which the total sum of quantized data exceeds a predetermined threshold is less than 1 during one scanning period of step S2, it is determined that the input operation has been erroneously detected or the input operation has been completed, and the input operation is waited. Return to the state (step S1).
Subsequently, it is determined whether the input operation position detected in step S2 is one place or a plurality of places (step S3). If a plurality of input operation positions are detected, a plurality of fingers (input operation bodies) are detected. ) The second detection circuit is activated by assuming that a multi-tap operation to bring 20 into contact with the input operation surface is attempted (step S4). If the input operation position is a single input operation position, the detected input operation is detected. After outputting the position to the host device (step S5), the process returns to step S2, and the detection of the input operation position where the first detection circuit is operated is repeated.
That is, in step S2 in which the input operation position is detected by operating the first detection circuit, the input operation position is detected even in a so-called hover operation in which theinput operation body 20 is operated while being away from the input operation surface. The multi-touch operation can be detected at the stage of the hover operation, and the second detection circuit can be activated before the input operation body 20 contacts the input operation surface. On the other hand, unless the multi-touch operation is detected, the first detection circuit operates to detect the input operation position even after the input operation body 20 touches the input operation surface, so that the two-dimensional input operation is performed at high speed and with high accuracy. The position can be detected.
When the second detection circuit is activated in step S4, it is determined whether or not one or more input operation positions are detected within a predetermined time by the second detection circuit (step S6), and a plurality of scanning cycles are determined. If the input operation position is not detected within the predetermined repeated time, it is determined that the input operation has ended, and the process returns to the standby state of the input operation (step S1). Here, the predetermined time is set to a time slightly longer than the operation time from when the hover operation is detected by the first detection circuit until the input operation surface is touched. Thereby, even if theinput operation body 20 exists in the input operation position before reaching the input operation surface which can be detected by the second detection circuit, it is not erroneously determined that the input operation has been completed.
When one or more input operation positions are detected by the second detection circuit, all detected input operation positions are output to the host device regardless of the number of detections (step S7), and the process returns to step S6. The detection of the input operation position where the second detection circuit is operated is repeated.
According to the present embodiment, the mutual detection type second detection circuit that does not cause a ghost problem is activated before the plurality ofinput operation bodies 20 intended for multi-touch operation come into contact with the input operation surface. The two-dimensional input operation position can be detected promptly without any time delay due to switching.
In addition, according to the present embodiment, thesame detection electrode 10 wired along the input operation surface is shared by the first detection circuit and the second detection circuit of the two types of detection methods, and each detection electrode 10 As the means for detecting the reception level Vi that appears, the circuit such as the Y-side analog multiplexer YMUX, the amplifier circuit 8, the A / D converter ADC, and the switching control circuit 12 is also used, so that without significant structural changes or addition of circuit parts, The first detection circuit and the second detection circuit can be selectively operated.
Furthermore, according to the present embodiment, when the input operation position is detected by the first detection circuit, all thedetection electrodes 10 are connected to the vibration power supply circuit 3 and the first input operation body 20 is collectively connected to the first operation body 20. Since it vibrates at the output level Vs of the AC detection signal SG, there is no need for drive control to apply the first AC detection signal SG for each detection electrode 10 that detects the reception level Vi, and one scanning cycle is shortened, resulting in higher speed. The input operation position can be detected. However, if the first AC detection signal SG whose relative potential varies between the detection electrode 10 and the input operation body 20 is generated, the first AC detection signal SG is detected for each detection electrode 10 that detects the reception level Vi. It may be applied, or the potential of the input operation body 20 side may be changed by the first AC detection signal SG.
In the above-described embodiment, the input operation position of a normal input operation that is not a multi-touch operation is detected by operating the first detection circuit, but theinput operation body 20 is in contact with the input operation surface. The operation operation position may be detected by operating the second detection circuit regardless of the multi-touch operation.
また、振動側回路基板2には、低圧振動電源線SGNDと高圧振動電源線SVCCとからなる振動電源回路3が配線されている。低圧振動電源線SGNDは低圧基準電源線GNDと、高圧振動電源線SVCCは高圧基準電源線VCCと、それぞれコイル5、6を介して接続している。コイル5とコイル6のインダクタンスは、いずれも後述する固有周波数fの第1交流検出信号SGに対してハイインピーダンスとなる値に設定され、ここでは、同一のインダクタンスLのコイル5、6を用いている。これにより、図1に示すように、基準電源回路4の低圧基準電源線GNDと高圧基準電源線VCCへ、固有周波数fの第1交流検出信号SGを同期させて出力すると、基準電源回路4の低圧基準電源線GNDが接地されて安定した電位にあるので、振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCの電位が、同期して固有周波数fで変動し、両者間の電圧は基準電源回路4と同じ直流出力電圧Vccを維持しながら振動する。
振動電源回路3が配線された振動側回路基板2には、図2に示すように、Y方向に配線された多数のX検出電極10X(10)とX方向に配線された多数のY検出電極10Y(10)とが、ダイオード7を介して振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCのいずれかの、ここでは低圧振動電源線SGNDに接続している。多数のX検出電極10XとY検出電極10Yは、振動側回路基板2若しくは別に設ける絶縁パネルの入力操作面となる表面に沿って互いに絶縁して配置され、操作者が入力操作体である指20を入力操作面に向けて入力操作を行うと、1又は2以上の検出電極10XとY検出電極10Yが指20に対向若しくは接近するように入力操作面の全面に配置されている。
振動側回路基板2には、更に、X検出電極10Xの接続を切り替えるX側アナログマルチプレクサXMUX、Y検出電極10Yの接続を切り替えるY側アナログマルチプレクサYMUX、マルチプレクサMUXの出力側に増幅回路8を介して接続するA/DコンバータADC、図1に示すように第1交流検出信号SGを発信する発信回路11、アナログマルチプレクサの接続を切り替え制御する切り替え制御回路12、X検出電極10Xへ第2交流検出信号SG’を発信する電極駆動回路13、座標演算回路14、インタフェース回路15等を内蔵するCPU9が実装され、いずれも振動電源回路3の低圧振動電源線SGNDと高圧振動電源線SVCCに接続し、DC電源16から出力電圧Vccを受けて動作している。
発信回路11の出力側は、二股に分岐してそれぞれコンデンサ17、18を介して低圧基準電源線GNDと高圧基準電源線VCCに接続している。コンデンサ17とコンデンサ18は、接続する電源線GND、VCCとの直流電圧を遮断する目的で介在させるので、それぞれのキャパシタンスは任意であるが、ここでは、同一のキャパシタンスCのコンデンサ17、18を用いている。
本実施の形態に係るタッチパネル1は、発信回路11から第1交流検出信号SGを発信する第1検出回路と、電極駆動回路13から第2交流検出信号SG’を発信する第2検出回路のいずれかを選択的に動作させ、入力操作体20の入力操作位置を検出する。
(第1検出回路の動作)
第1検出回路を動作させる場合には、振動電源回路3側の発信回路11から第1交流検出信号SGを二股に分岐するコンデンサ17、18を介して基準電源回路4の低圧基準電源線GNDと高圧基準電源線VCCに出力する。固有周波数fの固有発振信号SGが基準電源回路4と振動電源回路7に流れる場合に、低圧基準電源線GNDと高圧基準電源線VCC間及び低圧振動電源線SGNDと高圧振動電源線SVCC間が近接して配線され、固有周波数fの帯域でこれらの電源線間は短絡しているとすれば、図1の基準電源回路4と振動電源回路3は、図3の等価回路図で示される。
図3に示すように、振動電源回路3側の発信回路11の出力SGと基準電源回路4間には、並列にキャパシタンスCのコンデンサ17、18が接続されているので、その合成キャパシタンスは、2Cであり、また、基準電源回路4と振動電源回路3間に並列に接続されるコイル5、6の合成インダクタンスは、L/2となる。これらのキャパシタとインダクタは、固有周波数fの第1交流検出信号SGが流れる閉回路において直列に接続され、第1交流検出信号SGの振幅(レベル)をVi、コイル5、6両端の基準電源回路4と振動電源回路3間の電圧をVs、2πfで表される角速度をω(rad/sec)とすれば、
Vs=[ω2LC/(ω2LC−1)]Vi・・・(1)式
で表される。
ここで、図3に示す回路は、ω2LC=1で直列共振し、そのときの周波数f0は、
f0=1/[2π(LC)1/2]・・・(2)式
となる。
つまり、(2)式関係から得られる共振周波数f0を、第1交流検出信号SGの固有周波数fとすれば、第1交流検出信号SGの出力レベルVsに対して、(1)式から理論上振動電源回路3の電位が無限大で振動し、振動電源回路3に接続する検出電極10の電位も無限大に振動させることができる。その結果、検出電極10と指20との静電容量が10pF程度と微小であっても、検出電極10と指20間に発生する電圧が無限大に拡大するので、後述するようにCPU9の座演算回路14に入力される第1交流検出信号SGの受信レベルViは増大し、その検出が容易となる。
実際のタッチパネル1では、基準電源回路4と振動電源回路3のインダクタンス、浮遊容量などの影響から、(2)式から得る周波数f0で共振せず、また、基準電源回路4と振動電源回路3に第1交流検出信号SGが流れる際のエネルギーロス等により、振動電源回路3は、第1交流検出信号SGの出力レベルVsに対して有限倍率に拡大された振幅で電位が振動する。一方、操作者の指20が触れることのある検出電極10に大電圧を加えることはできないので、第1交流検出信号SGの固有周波数fを共振周波数f0を中心にずらしたり、第1交流検出信号SGの振幅を調整して、CPU9の座標演算回路14で入力操作が確実に検出できる範囲で、検出電極10の電圧振動の振幅を制限している。
全ての検出電極10が低圧振動電源線SGNDに接続することによって、その電位は固有周波数fで振動する一方、足下などの一部が接地している操作者の指(入力操作体)20の電位は定電位であるので、指20が接近して指20との静電容量Cfが増大する検出電極10では、検出電極10から指20へ静電容量Cfを介して固有周波数fの電圧信号が出力される。これを、固有周波数fで振動する振動電源回路3からみれば、入力操作により、指20が接近した検出電極10の電位が相対的に固有周波数fで振動することとなり、振動電源回路3で駆動するCPU9において、固有周波数fの電位変動信号、すなわち第1交流検出信号を検出でき、指20が接近する検出電極10で検出する第1交流検出信号の受信レベルViから入力操作を検出できる。
各検出電極10と入力操作体20間の静電容量Cmは、検出電極と入力操作体間の距離をd、真空の誘電率をε0、空気の比誘電率εを約1、入力操作体20と検出電極10の対向面積をsとして、Cm=ε0・εr・s/dで表され、この静電容量Cmの交流検出信号に対するリアクタンスXcは、交流検出信号の固有周波数がfであるので、Xc=1/(2π・f・Cm)から、Xc=d/(ω・ε0・εr・s)で表される。
図4は、入力操作体20と検出電極10間の電位Vsと検出電極10に表れる交流検出信号SGの受信レベルViの関係を表す第1検出回路の等価回路図であり、図中、Vsは、交流検出信号SGの出力レベル、すなわち検出電極10と入力操作体20間の電位、Cpは、検出電極10と低圧振動電源線SGND間の浮遊容量、rpは、検出電極10の内部抵抗値、R4は、出力抵抗の抵抗値である。図中の等価回路図では、
i1=i2+i3 ・・・(3)式
Vs=i1/(jω・Cm)+i2/(jω・Cp) ・・・(4)式
−i2/(jω・Cp)+i3・rp+i3・R4=0 ・・・(5)式
i3・R4=Vi ・・・(6)式
の関係が成り立ち、(3)式乃至(6)式から、
Vi=[jω・Cm/{1/R4+jω(Cm+Cp)(rp/R4+1)}]・Vs ・・・(7)式
の関係が得られる。
内部抵抗rpを0とし、R4がマルチプレクサMUXを介して後段の積分用オペアンプ8に接続されるので無限大とすれば、(7)式は、
Vi=Cm/(Cp+Cm)・Vs
と置き換えられ、更に
数10pFの浮遊容量Cpに比べて静電容量Cmは数10fFと極めて小さいので、(7)式は、更に
Vi=(Cm/Cp)・Vs ・・・(8)式
で表される。
上述の通り、入力操作体20と検出電極10のCmは、Cm=ε0・εr・s/dで表されるので、これを(8)式に代入して変形すれば、
Vi={ε0・εr・s/(d・Cp)}Vs ・・・(9)式
となり、入力操作中に指20と検出電極10との対向面積sがほぼ変化しないものとして、(9)式中の(ε0・εr・s/Cp)は、定数であるので、これを1/kとおけば、検出電極10に表れる第1交流検出信号SGの受信レベルViは、
Vi=Vs/(d・k) ・・・(10)式
で表され、指20との距離dが近い検出電極10ほど、受信レベルViが第1交流検出信号SGの出力レベルVsに近づく大きな値となる。ただし、指20が検出電極10に近接し、その間の静電容量Cmが数10pFの浮遊容量Cpに比べて無視できない程度に大きくなった場合には(10)式を適用できず、受信レベルViは最大で出力レベルVsとなる。
(10)式を用いれば、複数の各検出電極10に表れる第1交流検出信号の受信レベルViから、各検出電極10と指20の間の距離dを直接求めることができ、本実施の形態では、マルチプレクサMUXで切り替える全ての検出電極10(X検出電極10X、Y検出電極10Y)の配置位置と、各検出電極10から検出する受信レベルViとから、入力操作面に平行なXY方向の入力操作位置(x、y)と入力操作面に直交するZ方向の入力操作位置zの3次元の入力操作位置を検出する。
この入力操作位置(x、y、z)を検出するために、CPU9の切り替え制御回路12は、X側アナログマルチプレクサXMUXとY側アナログマルチプレクサYMUXを切り替え制御し、一走査周期で全てのX検出電極10XとY検出電極10Yを各検出電極10毎に順に積分用オペアンプからなる増幅回路8へ接続する。これにより、全ての検出電極10に表れる第1交流検出信号の受信レベルViは、増幅回路8で増幅された後、A/DコンバータADCに入力される。
A/DコンバータADCは、第1交流検出信号SGの固有周波数fの少なくとも2倍以上の周波数でサンプリングし、第1交流検出信号SGの受信レベルViを量子化してCPU9の座標演算回路14へ出力する。
A/Dコンバータ14から出力される量子化データは、その時にアナログマルチプレクサMUXが選択接続した検出電極10に表れる第1交流検出信号SGの受信レベルViを表すので、入力操作位置を検出する座標演算回路14では、その検出電極10が増幅回路8に接続する接続期間中にA/DコンバータADCから入力された量子化データの総和を所定の閾値と比較し、所定の閾値以上である場合に入力操作体20が接近した検出電極10と判定する。判定された検出電極10から検出した第1交流検出信号SGの受信レベルViを用いて、(10)式からその検出電極10の配置位置と入力操作体20との距離dが得られるので、同様に判定された複数の各検出電極10の入力操作面上のX方向若しくはY方向の配設位置と受信レベルViとから入力操作面上の二次元の入力操作位置及び/又は入力操作面上のZ方向の高さを含む三次元の入力操作位置を検出する。
CPU9は、座標演算回路14が一走査周期中に、入力操作位置が入力操作面上にあるか否かにかかわらず、複数の入力操作位置を検出した場合には、発信回路11からの第1交流検出信号SGを発信を停止して、第1検出回路から相互容量方式で入力操作位置を検出する第2検出回路に動作を切り替える。一方、複数の入力操作位置を検出しない限り、単一の入力操作体20による入力操作であるとして、座標演算回路14が検出した二次元若しくは三次元の入力操作位置を、インターフェース回路15から直流が絶縁された信号線19を介して、USB通信、I2C通信等で入力操作位置を利用する上位機器に出力される。
この第1検出回路では、いずれかの検出電極10と入力操作体20との距離dが、その検出電極10で検出した第1交流検出信号SGの受信レベルViの逆数に比例する((10)式参照)ので、XY方向で交差配置されるX検出電極10XとY検出電極10Yで検出する受信レベルViから、入力操作面上のZ方向の高さを含む三次元の入力操作位置を精度良く検出できる。
また、一走査周期に、検出電極10(X検出電極10XとY検出電極10Y)の配線数に相当する走査で各検出電極10の受信レベルViを検出するだけで、入力操作面上の二次元の入力操作位置を検出できるので、検出電極の全ての交点について走査する相互容量方式に比べて高速にかつ低消費電力で入力操作位置を検出できる。
(第2検出回路の動作)
第2検出回路を動作させる場合には、発信回路11からの第1交流検出信号SGの発信を停止し、CPU9に内蔵の第2発信手段となる電極駆動回路13から第2交流検出信号SG’を発信し、相互容量方式で入力操作体20の二次元の入力操作位置を検出する。
第1交流検出信号SGの発信が停止することにより、振動電源回路3の電位振動も停止するが、振動側回路基板2に搭載された各回路部品は、コイル5、6を介したDC電源16の電源で動作する。第2検出回路では、複数のX検出電極10X若しくは複数のY検出電極10Yの一方を第2交流検出信号SG’を印加する駆動電極D(n)、他方を第2交流検出信号SG’の受信レベルViを検出する検出電極S(m)とし、入力操作面上の全ての駆動電極D(n)と検出電極S(m)の交点(n、m)について第2交流検出信号SG’の受信レベルViを検出する。
特定の交点(n、m)に入力操作体20が接近すると、その交点(n、m)の駆動電極D(n)に第2交流検出信号SG’を印加しているタイミングで、交点(n、m)の検出電極S(m)に表れる受信レベルViは、第2交流検出信号SG’の一部が入力操作体20に流れて減少するので、受信レベルViが所定の閾値未満となる全ての交点(n、m)で交差する駆動電極D(n)と検出電極S(m)のXY方向の配線位置から入力操作体20の二次元の入力操作位置を検出する。
本実施の形態では、複数のX検出電極10Xを駆動電極D(n)として、切り替え制御回路12は、X側アナログマルチプレクサXMUXを切り替え制御して、電極駆動回路13を各X検出電極10Xに切り替え接続し、各X検出電極10Xへ順に第2交流検出信号SG’を印加する。第2交流検出信号SG’の出力レベルVsや交流周波数は任意であるが、ここでは受信レベルViの検出に第1検出回路の検出回路を共用するので、第1交流検出信号SGの出力レベルVs及び周波数fと同一とする。しかしながら、第1交流検出信号SGと第2交流検出信号SG’の出力レベルVsを必ずしも一致させる必要はないので、電極駆動回路13を発信回路11で代用し、第1交流検出信号SGを第2交流検出信号SG’として各X検出電極10Xへ印加させてもよい。
いずれかのX検出電極10X(駆動電極D(n))に第2交流検出信号SG’を印加している間、切り替え制御回路12はY側アナログマルチプレクサYMUXを切り替え制御して、その駆動電極D(n)に絶縁して交差する全てのY検出電極10Yを順に増幅回路8へ接続し、第2交流検出信号SG’の受信レベルViを検出する検出電極S(m)とする。これにより、全ての交点(n、m)について、検出電極S(m)に表れる第2交流検出信号SG’受信レベルViは、増幅回路8で増幅された後、A/DコンバータADCに入力され、A/DコンバータADCは、第2交流検出信号SG’の固有周波数fの少なくとも2倍以上の周波数でサンプリングし、第2交流検出信号SG’の受信レベルViを量子化してCPU9の座標演算回路14へ出力する。
CPU9の切り替え制御回路12は、一走査期間中に同様の切り替え制御を繰り返し、全てのX検出電極10XとY検出電極10Yの交点(n、m)について検出された受信レベルViを順に座標演算回路14へ出力する。
ここで、各交点(n、m)について検出された受信レベルViは、交点(n、m)で交差する駆動電極D(n)と検出電極S(m)間の相互容量の変化量を表し、入力操作体20と交点(n、m)との距離が接近するほど低下する。そこで、座標演算回路14は、全ての交点(n、m)について検出された受信レベルViを、X検出電極10Xの配置順であるX方向と、Y検出電極10Yの配置順であるY方向に沿って比較し、極小値が検出された交点(n、m)の近傍に入力操作があったとものとし、その交点(n、m)を含む周囲の交点(n、m)について検出された受信レベルViのXY方向の重心からXY方向の二次元の入力操作位置を検出する。
この第2検出回路では、2本の指20を同時に入力操作面に触れて入力操作を行ういわゆるマルチタッチ操作であっても、全ての交点(n、m)について受信レベルViを検出するので、指20の入力操作により受信レベルViが極小値となる交点(n、m)のみを検出することができ、ゴースト発生の問題がなく、複数の二次元の各入力操作位置を正確に検出できる。
CPU9は、第2検出回路を動作させて検出した複数の入力操作位置についても、インターフェース回路15から直流が絶縁された信号線19を介して、USB通信、I2C通信等で入力操作位置を利用する上位機器に出力する。
第2検出回路が動作している間に、発信回路11は第1交流検出信号SGの発信を停止し、コンデンサ17、18側からみた発信回路11の出力インピーダンスを低インピーダンスとしている。従って、振動電源回路3と基準電源回路4の間には、コイル5、6とコンデンサ17、18からなるローパスフィルタが形成され、DC電源16側と振動側回路基板2に実装された各回路部品との間で互いに相手側に高周波ノイズが伝達されない。
以下、このように構成された静電容量式タッチパネル1の動作を、図5のフローチャートで説明する。入力操作が行われていない待機状態では、第1検出回路が動作している(ステップS1)。第1検出回路の動作では、振動電源回路3の電位を振動させるだけで、高圧振動電源線SVCCと低圧振動電源線SGND間や高圧基準電源線VCCと低圧基準電源線GND間に電流が流れないので、極めて少ない消費電力で入力操作を検出できる。
特定の検出電極10について検出した受信レベルViを表す量子化データの総和が所定の閾値以上となった場合には、入力操作面に接近する入力操作があったものと推測して、一走査期間中に量子化データの総和が所定の閾値を超えた複数の検出電極10の受信レベルViから二次元若しくは入力操作面から離れたZ方向を含む三次元の入力操作位置を検出する(ステップS2)。
ステップS2の一走査期間中に、量子化データの総和が所定の閾値を超える検出電極10が1未満である場合には、入力操作の誤検出若しくは入力操作が終了したものとして、入力操作の待機状態(ステップS1)に戻る。
続いて、ステップS2で検出した入力操作位置が1カ所であるか複数箇所であるかを判定し(ステップS3)、複数の入力操作位置が検出された場合には、複数の指(入力操作体)20を入力操作面に接触させるマルチタップ操作が試みられていると推測して第2検出回路を起動し(ステップS4)、単一の入力操作位置である場合には、その検出した入力操作位置を上位装置へ出力した後(ステップS5)、ステップS2に戻り、第1検出回路を動作させた入力操作位置の検出を繰り返す。
つまり、第1検出回路を動作させて入力操作位置を検出するステップS2では、入力操作体20を入力操作面から離れた状態のまま操作するいわゆるホバー操作であっても、入力操作位置を検出することができ、マルチタッチ操作をホバー操作の段階で検出し、入力操作体20が入力操作面に接触する前に第2検出回路を起動させることができる。一方、マルチタッチ操作が検出されない限り、入力操作体20が入力操作面に接触した後も第1検出回路が動作して入力操作位置を検出するので、高速にかつ高精度に2次元の入力操作位置を検出できる。
ステップS4で第2検出回路を起動させた場合には、第2検出回路で所定時間内に1又は2以上の入力操作位置を検出したかどうかを判定し(ステップS6)、複数の走査周期を繰り返す所定時間内に入力操作位置が検出されなかった場合には、入力操作が終了したとして入力操作の待機状態(ステップS1)に戻る。ここで、所定時間は、第1検出回路でホバー操作が検出されてから入力操作面に触れるまでの操作時間よりわずかに長い時間に設定する。これにより、入力操作体20が、第2検出回路で検出可能な入力操作面に達する前の入力操作位置にあっても、入力操作が終了したものと誤判定されることがない。
第2検出回路で1又は2以上の入力操作位置を検出した場合には、その検出数にかかわらず、全ての検出した入力操作位置を上位装置へ出力した後(ステップS7)、ステップS6に戻り、第2検出回路を動作させた入力操作位置の検出を繰り返す。
本実施の形態によれば、マルチタッチ操作を意図した複数の入力操作体20が入力操作面に接触する前に、ゴースト問題が発生しない相互容量方式の第2検出回路を起動させるので、検出方式の切り替えによる時間の遅れがなく、すみやかに二次元の入力操作位置を検出できる。
また、本実施の形態によれば、2種類の検出方式の第1検出回路と第2検出回路で入力操作面に沿って配線された同一の検出電極10を兼用するとともに、各検出電極10に表れる受信レベルViの検出手段として、Y側アナログマルチプレクサYMUX、増幅回路8、A/DコンバータADC、切り替え制御回路12等の回路を兼用するので、大幅な構造変更や回路部品を追加することなく、第1検出回路と第2検出回路を選択的に動作させることができる。
更に、本実施の形態によれば、第1検出回路により入力操作位置を検出する際に、全ての検出電極10を振動電源回路3に接続して、一括して入力操作体20に対し第1交流検出信号SGの出力レベルVsで振動させるので、受信レベルViを検出する検出電極10毎に第1交流検出信号SGを印加する駆動制御の必要がなく、一走査周期が短縮し、より高速に入力操作位置を検出できる。しかしながら、検出電極10と入力操作体20の間に相対電位が変動する第1交流検出信号SGを発生させるものであれば、受信レベルViを検出する検出電極10毎に第1交流検出信号SGを印加してもよく、又、入力操作体20側を第1交流検出信号SGで電位変動させてもよい。
また、上述の実施の形態では、マルチタッチ操作ではない通常の入力操作の入力操作位置は、第1検出回路を動作させて検出しているが、入力操作体20が入力操作面に接触する入力操作操作位置は、マルチタッチ操作であるかにかかわらず、第2検出回路を動作させて検出してもよい。 A configuration of a capacitive touch panel (hereinafter referred to as a touch panel) 1 according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, main circuit components constituting the
The vibration side circuit board 2 is provided with a vibration
As shown in FIG. 2, the vibration circuit board 2 to which the vibration
The vibration side circuit board 2 further includes an X side analog multiplexer XMUX for switching the connection of the
The output side of the
(Operation of the first detection circuit)
When operating the first detection circuit, the low-voltage reference power line GND of the reference power circuit 4 is connected to the first AC detection signal SG from the
As shown in FIG. 3, since
Vs = [ω 2 LC / (ω 2 LC-1)] Vi (1).
Here, the circuit shown in FIG. 3 resonates in series at ω 2 LC = 1, and the frequency f 0 at that time is
f 0 = 1 / [2π (LC) 1/2 ] (2).
That is, if the resonance frequency f 0 obtained from the relationship of the expression (2) is the natural frequency f of the first AC detection signal SG, the theory from the expression (1) is obtained with respect to the output level Vs of the first AC detection signal SG. The potential of the upper vibration
The
When all the
The electrostatic capacitance Cm between each
FIG. 4 is an equivalent circuit diagram of the first detection circuit showing the relationship between the potential Vs between the
i1 = i2 + i3 (3) Formula Vs = i1 / (jω · Cm) + i2 / (jω · Cp) (4) Formula −i2 / (jω · Cp) + i3 · rp + i3 · R4 = 0 -(5) Formula i3 * R4 = Vi ... The relationship of Formula (6) is established, and from Formula (3) to Formula (6),
Vi = [jω · Cm / {1 / R4 + jω (Cm + Cp) (rp / R4 + 1)}] · Vs (7) Equation (7) is obtained.
If the internal resistance rp is set to 0, and R4 is connected to the integrating
Vi = Cm / (Cp + Cm) · Vs
Since the electrostatic capacitance Cm is extremely small, such as several tens of fF, compared to the floating capacitance Cp of several tens of pF, the equation (7) is further expressed by the following equation: Vi = (Cm / Cp) · Vs (8) expressed.
As described above, Cm of the
Vi = {ε0 · εr · s / (d · Cp)} Vs (9) Assuming that the facing area s between the
Vi = Vs / (d · k) (Expression (10)), and the detection level of the
If Expression (10) is used, the distance d between each
In order to detect this input operation position (x, y, z), the switching
The A / D converter ADC samples at a frequency at least twice the natural frequency f of the first AC detection signal SG, quantizes the reception level Vi of the first AC detection signal SG, and outputs it to the coordinate
Since the quantized data output from the A /
When the coordinate
In the first detection circuit, the distance d between any one of the
Further, only by detecting the reception level Vi of each
(Operation of the second detection circuit)
When operating the second detection circuit, the transmission of the first AC detection signal SG from the
By stopping the transmission of the first AC detection signal SG, the potential vibration of the vibration
When the
In the present embodiment, the switching
While the second AC detection signal SG ′ is applied to any one of the
The switching
Here, the reception level Vi detected at each intersection (n, m) represents the amount of change in mutual capacitance between the drive electrode D (n) and the detection electrode S (m) that intersect at the intersection (n, m). As the distance between the
In the second detection circuit, the reception level Vi is detected for all the intersections (n, m) even in the so-called multi-touch operation in which the two
The
While the second detection circuit is operating, the
Hereinafter, the operation of the
When the sum of the quantized data representing the reception level Vi detected for the
If the number of
Subsequently, it is determined whether the input operation position detected in step S2 is one place or a plurality of places (step S3). If a plurality of input operation positions are detected, a plurality of fingers (input operation bodies) are detected. ) The second detection circuit is activated by assuming that a multi-tap operation to bring 20 into contact with the input operation surface is attempted (step S4). If the input operation position is a single input operation position, the detected input operation is detected. After outputting the position to the host device (step S5), the process returns to step S2, and the detection of the input operation position where the first detection circuit is operated is repeated.
That is, in step S2 in which the input operation position is detected by operating the first detection circuit, the input operation position is detected even in a so-called hover operation in which the
When the second detection circuit is activated in step S4, it is determined whether or not one or more input operation positions are detected within a predetermined time by the second detection circuit (step S6), and a plurality of scanning cycles are determined. If the input operation position is not detected within the predetermined repeated time, it is determined that the input operation has ended, and the process returns to the standby state of the input operation (step S1). Here, the predetermined time is set to a time slightly longer than the operation time from when the hover operation is detected by the first detection circuit until the input operation surface is touched. Thereby, even if the
When one or more input operation positions are detected by the second detection circuit, all detected input operation positions are output to the host device regardless of the number of detections (step S7), and the process returns to step S6. The detection of the input operation position where the second detection circuit is operated is repeated.
According to the present embodiment, the mutual detection type second detection circuit that does not cause a ghost problem is activated before the plurality of
In addition, according to the present embodiment, the
Furthermore, according to the present embodiment, when the input operation position is detected by the first detection circuit, all the
In the above-described embodiment, the input operation position of a normal input operation that is not a multi-touch operation is detected by operating the first detection circuit, but the
本発明は、マルチタッチ操作を認識して複数の各入力操作位置を検出する静電容量式タッチパネルに適している。
The present invention is suitable for a capacitive touch panel that recognizes a multi-touch operation and detects a plurality of input operation positions.
1 静電容量式タッチパネル
3 振動電源回路
4 基準電源回路
5 コイル(第2インダクタ)
6 コイル(第1インダクタ)
10X X検出電極(第1電極)
10Y Y検出電極(第2電極)
11 発信回路(第1発信手段)
13 電極駆動回路(第2発信手段)
14 座標演算回路(第1検出回路、第2検出回路)
16 DC電源(直流電源)
17 コンデンサ(第1キャパシタ)
18 コンデンサ(第2キャパシタ) 1Capacitive Touch Panel 3 Vibration Power Supply Circuit 4 Reference Power Supply Circuit 5 Coil (Second Inductor)
6 Coil (first inductor)
10X X detection electrode (first electrode)
10Y Y detection electrode (second electrode)
11 Transmission circuit (first transmission means)
13 Electrode drive circuit (second transmission means)
14 Coordinate operation circuit (first detection circuit, second detection circuit)
16 DC power supply (DC power supply)
17 Capacitor (first capacitor)
18 Capacitor (second capacitor)
3 振動電源回路
4 基準電源回路
5 コイル(第2インダクタ)
6 コイル(第1インダクタ)
10X X検出電極(第1電極)
10Y Y検出電極(第2電極)
11 発信回路(第1発信手段)
13 電極駆動回路(第2発信手段)
14 座標演算回路(第1検出回路、第2検出回路)
16 DC電源(直流電源)
17 コンデンサ(第1キャパシタ)
18 コンデンサ(第2キャパシタ) 1
6 Coil (first inductor)
10X X detection electrode (first electrode)
10Y Y detection electrode (second electrode)
11 Transmission circuit (first transmission means)
13 Electrode drive circuit (second transmission means)
14 Coordinate operation circuit (first detection circuit, second detection circuit)
16 DC power supply (DC power supply)
17 Capacitor (first capacitor)
18 Capacitor (second capacitor)
Claims (5)
- 絶縁基板の入力操作面に沿って第1方向に配線される複数の第1検出電極と、
前記入力操作面に沿って第1方向と交差する第2方向に配線される複数の第2検出電極と、
第1検出電極と第2検出電極の各検出電極と入力操作体との相対電位が変動する第1交流検出信号を発信する第1発信手段と、前記各検出電極と入力操作体間の静電容量を介して、前記各検出電極に表れる第1交流検出信号の受信レベルを検出する第1信号検出手段とを有し、前記各検出電極毎に検出した第1交流検出信号の受信レベルをもとにその検出電極と入力操作体間の距離を求め、各検出電極の入力操作体との距離を比較して入力操作体の入力操作位置を検出する第1検出回路と、
複数の第1検出電極へ順に第2交流検出信号を発信する第2発信手段と、第1検出電極と第2検出電極間の静電容量を介して、第2交流検出信号を発信した第1検出電極に交差する複数の各第2検出電極に表れる第2交流検出信号の受信レベルを検出する第2信号検出手段とを有し、入力操作体が接近し受信レベルが変化する第1検出電極と第2検出電極の絶縁基板上の交差位置から、入力操作面上の入力操作体の入力操作位置を検出する第2検出回路と、
第1検出回路が2以上の入力操作体による入力操作位置を検出した場合にマルチタッチ操作と判定する判定手段と、
判定手段の判定結果によって第1検出回路と第2検出回路のいずれかの動作に切り替える切替制御回路とを備え、
判定手段がマルチタッチ操作と判定しない場合には、第1検出回路を動作させて入力操作面上の入力操作体の入力操作位置を検出し、
判定手段がマルチタッチ操作と判定した場合には、第2検出回路を動作させて入力操作面上の2以上の入力操作体の入力操作位置をそれぞれ検出することを特徴とする静電容量式タッチパネル。 A plurality of first detection electrodes wired in a first direction along the input operation surface of the insulating substrate;
A plurality of second detection electrodes wired in a second direction intersecting the first direction along the input operation surface;
First transmission means for transmitting a first AC detection signal in which a relative potential between each detection electrode of the first detection electrode and the second detection electrode and the input operation body varies, and electrostatic between each of the detection electrodes and the input operation body. First signal detection means for detecting the reception level of the first AC detection signal appearing on each detection electrode via a capacitor, and also having the reception level of the first AC detection signal detected for each detection electrode. A first detection circuit that obtains a distance between the detection electrode and the input operation body, compares the distance between each detection electrode and the input operation body, and detects an input operation position of the input operation body;
A second transmitter for transmitting a second AC detection signal to the plurality of first detection electrodes in sequence, and a first transmitter for transmitting the second AC detection signal via a capacitance between the first detection electrode and the second detection electrode; First detection electrode having a second signal detection means for detecting a reception level of the second AC detection signal appearing on each of the plurality of second detection electrodes intersecting with the detection electrode, wherein the input operation body approaches and the reception level changes. And a second detection circuit for detecting an input operation position of the input operation body on the input operation surface from an intersection position of the second detection electrode on the insulating substrate;
Determination means for determining a multi-touch operation when the first detection circuit detects an input operation position by two or more input operation bodies;
A switching control circuit for switching to the operation of either the first detection circuit or the second detection circuit according to the determination result of the determination means;
If the determination means does not determine multi-touch operation, the first detection circuit is operated to detect the input operation position of the input operation body on the input operation surface,
A capacitive touch panel, wherein when the determination means determines that the operation is a multi-touch operation, the second detection circuit is operated to detect input operation positions of two or more input operation bodies on the input operation surface, respectively. . - 判定手段は、第1検出回路が入力操作面上の入力操作体の入力操作位置を検出する前に、2以上の入力操作体による入力操作位置を検出した場合に、マルチタッチ操作と判定することを特徴とする請求項1記載の静電容量式タッチパネル装置。 The determining means determines that the operation is a multi-touch operation when the input operation position of two or more input operation bodies is detected before the first detection circuit detects the input operation position of the input operation body on the input operation surface. The capacitive touch panel device according to claim 1.
- 切替制御回路は、判定手段がマルチタッチ操作と判定した場合には、第1検出回路から第2検出回路へ動作を切り替え、第2検出回路が入力操作面上のいずれの入力操作体の入力操作位置も検出しない場合に、第2検出回路から第1検出回路へ動作を切り替えることを特徴とする請求項1又は請求項2のいずれか1項に記載の静電容量式タッチパネル装置。 The switching control circuit switches the operation from the first detection circuit to the second detection circuit when the determination unit determines that the operation is a multi-touch operation, and the second detection circuit performs an input operation on any input operation body on the input operation surface. The capacitive touch panel device according to claim 1, wherein when the position is not detected, the operation is switched from the second detection circuit to the first detection circuit.
- 第1検出回路は、更に、一方を接地若しくは定電位とした低圧基準電源線と高圧基準電源線との間に直流電圧を出力する一次直流電源回路と、
低圧振動電源線と高圧振動電源線との間から直流電圧を出力する二次直流電源回路と、
低圧基準電源線と低圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第1インダクタと、
高圧基準電源線と高圧振動電源線間に接続され、第1交流検出信号に対してハイインピーダンスとなる第2インダクタと、
二次直流電源回路で動作する第1発信手段と高圧基準電源線及び低圧基準電源線間にそれぞれ接続される第1キャパシタ及び第2キャパシタとを備え、
第1検出回路を動作させる間は、
第2発信手段の動作を停止し、第1発信手段から、第1キャパシタと第2キャパシタを介して、一次直流電源回路へ第1交流検出信号を出力するとともに、
前記各検出電極を、二次直流電源回路の低圧振動電源線と高圧振動電源線のいずれかに接続して第1交流検出信号の周波数で振動させ、
第2検出回路を動作させる間は、
第2発信手段から複数の第1検出電極へ順に第2交流検出信号を出力するとともに、第1発信手段の第1キャパシタと第2キャパシタからみた出力インピーダンスを低インピーダンスとして第1発信手段の第1交流検出信号の出力を停止することを特徴とする請求項1乃至請求項3のいずれか1項に記載の静電容量式タッチパネル。 The first detection circuit further includes a primary DC power supply circuit that outputs a DC voltage between the low-voltage reference power supply line and the high-voltage reference power supply line, one of which is grounded or at a constant potential.
A secondary DC power supply circuit that outputs a DC voltage from between the low-voltage vibration power supply line and the high-voltage vibration power supply line;
A first inductor connected between the low-voltage reference power line and the low-voltage vibration power line and having a high impedance with respect to the first AC detection signal;
A second inductor connected between the high-voltage reference power line and the high-voltage vibration power line and having a high impedance with respect to the first AC detection signal;
First transmission means operating in the secondary DC power supply circuit, and a first capacitor and a second capacitor connected between the high-voltage reference power line and the low-voltage reference power line, respectively.
While operating the first detection circuit,
The operation of the second transmission means is stopped, and the first transmission detection signal is output from the first transmission means to the primary DC power supply circuit via the first capacitor and the second capacitor,
Each of the detection electrodes is connected to one of the low-voltage vibration power line and the high-voltage vibration power line of the secondary DC power circuit and vibrated at the frequency of the first AC detection signal,
While operating the second detection circuit,
The second alternating-current detection signal is sequentially output from the second transmission means to the plurality of first detection electrodes, and the output impedance viewed from the first capacitor and the second capacitor of the first transmission means is set to a low impedance so that the first of the first transmission means The capacitive touch panel according to any one of claims 1 to 3, wherein the output of the AC detection signal is stopped. - 絶縁基板の入力操作面に沿って第1方向に配線される複数の第1検出電極と第1方向と交差する第2方向に配線される複数の第2検出電極の各検出電極に、入力操作体との相対電位が変動する第1交流検出信号を発信し、
前記各検出電極と入力操作体間の静電容量を介して、前記各検出電極に表れる第1交流検出信号の受信レベルを検出し、
前記各検出電極毎に検出した第1交流検出信号の受信レベルをもとにその検出電極と入力操作体間の距離を求め、各検出電極の入力操作体との距離を比較して入力操作体の入力操作位置を検出し、
検出した入力操作位置が入力操作面に達するまで、単一の入力操作体による入力操作位置を検出した場合には、その入力操作面上の入力操作体の入力操作位置を検出し、
検出した入力操作位置が入力操作面に達する前に、2以上の入力操作体による入力操作位置を検出した場合に、第1交流検出信号の発信を停止するとともに、複数の第1検出電極へ順に第2交流検出信号を発信し、
第1検出電極と第2検出電極間の静電容量を介して、第2交流検出信号を発信した第1検出電極に交差する複数の各第2検出電極に表れる第2交流検出信号の受信レベルを検出し、
入力操作体が接近し受信レベルが変化する第1検出電極と第2検出電極の絶縁基板上の交差位置から、入力操作面上の入力操作体の入力操作位置を検出することを特徴とする静電容量式タッチパネルの入力操作位置検出方法。 An input operation is performed on each detection electrode of the plurality of first detection electrodes wired in the first direction along the input operation surface of the insulating substrate and the plurality of second detection electrodes wired in the second direction intersecting the first direction. A first alternating current detection signal whose relative potential with the body fluctuates is transmitted,
Detecting the reception level of the first AC detection signal appearing on each detection electrode via the capacitance between each detection electrode and the input operation body;
Based on the reception level of the first AC detection signal detected for each detection electrode, the distance between the detection electrode and the input operation body is obtained, and the distance between the detection electrode and the input operation body is compared with the input operation body. The input operation position of
When the input operation position by a single input operation body is detected until the detected input operation position reaches the input operation surface, the input operation position of the input operation body on the input operation surface is detected,
When the input operation position by two or more input operation bodies is detected before the detected input operation position reaches the input operation surface, the transmission of the first AC detection signal is stopped and the plurality of first detection electrodes are sequentially arranged. Send the second AC detection signal,
The reception level of the second AC detection signal appearing on each of the plurality of second detection electrodes that intersects the first detection electrode that has transmitted the second AC detection signal via the capacitance between the first detection electrode and the second detection electrode. Detect
An input operation position of the input operation body on the input operation surface is detected from an intersection position on the insulating substrate of the first detection electrode and the second detection electrode at which the input operation body approaches and the reception level changes. An input operation position detection method for a capacitive touch panel.
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JP2010282462A (en) * | 2009-06-05 | 2010-12-16 | Smk Corp | Capacity type touch panel |
JP2012208689A (en) * | 2011-03-29 | 2012-10-25 | Smk Corp | Electrostatic capacitance type touch panel |
JP2013242699A (en) * | 2012-05-21 | 2013-12-05 | Renesas Electronics Corp | Semiconductor device |
Cited By (3)
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CN108108055A (en) * | 2018-01-02 | 2018-06-01 | 联想(北京)有限公司 | Touch device, touch control method and electronic equipment |
CN114546168A (en) * | 2022-02-24 | 2022-05-27 | 汇春科技(成都)有限公司 | Self-capacitance detection circuit, touch detection method and device |
CN114546168B (en) * | 2022-02-24 | 2023-07-21 | 汇春科技(成都)有限公司 | Self-capacitance detection circuit, touch detection method and device |
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