WO2013018120A1 - Capacitive touch panel - Google Patents

Abstract

[Problem] To provide a capacitive touch panel having excellent visibility of a display disposed on the rear surface side, without disposing a transparent member on the operation input surface. [Solution] The receiving level of AC detection signals that appear in a plurality of detection electrodes via the capacitance between the detection electrodes and input operation units is essentially proportional to the distance between the detection electrodes and the input operation units. Therefore, the relative distances between the positions of the input operation units and the detection electrodes are compared on the basis of the receiving level of the AC detection signals detected in each of the detection electrodes, and the operation input positions of the operation input units are detected.

Description

Capacitive touch panel

The present invention relates to a capacitive touch panel that detects an input operation position of an input operation body from an arrangement position of a detection electrode where an input operation body such as a finger approaches and a capacitance of the finger increases.

As a touch device for pointing and inputting icons displayed on the display of electronic devices, various touch detection methods such as electrostatic capacitance method, resistive film method and optical method are used from the difference in detection method of input operation position. It is done. Among them, in the resistive touch panel, a resistive film having a uniform resistance value per unit length is disposed along the input operation surface, and the distance between the detection electrode and the input operation position is specified from the resistance value of the input operation position. To detect the operation position, it is necessary to form the detection electrode and the resistance film arranged along the surface or the back of the input operation surface with an expensive transparent body so that the display installed on the back side can be seen visually Since the transmittance also decreases as a transparent body, there is a problem that the display is difficult to see.

In the optical touch panel, plural pairs of light emitting elements and light receiving elements are disposed around the input operation surface to form a grid-like light path along the input operation surface, and the pairs whose light path is interrupted by the input operation The input operation position is detected from the arrangement position of the light emitting element and the light receiving element, but similarly it is expensive because it is necessary to provide plural pairs of light emitting element and light receiving element, and also by foreign matter on the input operation surface. The light path was interrupted and misrecognition occurred frequently.

The capacitive touch panel focuses on the fact that the floating capacitance (capacitance between the input operating body and the detection electrode) of the detection electrode to which the input operating body approaches due to the input operation increases. The input operation position to the input operation surface on which the detection electrode is arranged is detected from the change in capacitance. Conventionally, a large number of X-side detection electrodes and Y-side detection electrodes are intersected on the front and back of the insulating substrate. Capacitance for detecting the input operation position by the input operation body from the arrangement position of the X-side detection electrode and the Y-side detection electrode which are formed in a matrix and the capacitance increases in the vicinity of the input operation body such as a finger. An expression touch panel is known (patent document 1).

However, this capacitive touch panel is required to dispose a large number of X-side detection electrodes and Y-side detection electrodes along the input operation surface, and be formed of a transparent body so that the display on the back side can be viewed. In order to increase the detection resolution of the input operation position, it is necessary to closely arrange a large number of X-side detection electrodes and Y-side detection electrodes. Since the change in the capacitance of the sensor was detected, the input operation position could not be detected in a short time.

Therefore, a capacitive touch panel has been proposed in which a detection electrode is disposed only around the input operation surface and an input position is detected from a change in capacitance between the input operation body and the detection electrode (Patent Document 2). In the capacitive touch panel described in Patent Document 2, a touch member made of a dielectric with a high dielectric constant is disposed along the entire input operation surface, and the capacitance between the input operation position and the detection electrode is The input operation position on the input operation surface is detected from the change in the capacitance which is enlarged by the touch member having a high dielectric constant compared with the inside and the detection sensitivity is increased to detect.

There is also known an electrostatic capacitance type detection device in which detection electrodes are arranged around an input operation surface so as to detect a three-dimensional input operation (Patent Document 3). The capacitance type detection device described in Patent Document 3 has a pair of detection electrodes on both sides facing each other in the detection direction (for example, the X direction) around the input operation surface, and a pair of detection electrodes on the same input operation surface The drive electrodes are arranged equidistantly from. When there is an input operation on the input operation body which is another dielectric on the input operation surface, the capacitance between the pair of detection electrodes and the drive electrode is interrupted by the input operation body and changes, so the input operation The input operation position in the X direction is detected from the difference in electrostatic capacitance for each detection electrode, which changes due to.

Detection of the input operation position in the Y direction orthogonal to the X direction is driven at equal distances from the pair of detection electrodes on both sides facing in the Y direction around the input operation surface and from the pair of detection electrodes on the same input operation surface The electrodes are arranged, and similarly, the input operation position in the Y direction is detected. In the detection device described in Patent Document 3, when detecting the input operation position in the X direction and the Y direction, the detection electrode and the drive electrode are switched to share the same electrode, and the number of electrodes disposed around the input operation surface Is halved.

In addition, detection of the input operation position in the Z direction orthogonal to the XY plane, assuming another input operation surface orthogonal to the input operation surface, further includes a pair of detection electrodes and a pair of detection electrodes facing the periphery in the Z direction. Drive electrodes equidistant from the detection electrode are disposed, and similarly, the input operation position in the Z direction is detected.

Japanese Patent Application Publication No. 2005-337773 JP-A-8-171449 International Publication WO2008 / 093683

In the capacitive touch panel disclosed by Patent Document 1, since a large number of detection electrodes are disposed on the input operation surface, it is necessary to use a transparent conductor when disposing a display on the back side, Since the transparent conductor is not a perfect transparent body, its transmittance is limited, and there is a problem in that it affects the visibility of the display on the back side.

Even in the capacitive touch panel disclosed in Patent Document 2 in which the detection electrode is not disposed on the input operation surface in order to solve this problem, the touch member is disposed in parallel to the input operation surface, so the transmittance The problem of decline can not be solved essentially.

In addition, if the touch operation member such as a finger is touched to the touch member to perform the input operation, the capacitance between the input operation body and the detection electrode does not change significantly, so it is necessary to touch the touch member to perform the input operation Yes, it is limited to detection of a two-dimensional input operation position parallel to the input operation surface. Furthermore, since the input operation can not be performed unless the touch member is touched, the operability is impaired, and the touch member which is touched by the input operation body to be transparent becomes dirty, the appearance is deteriorated, and the transmittance is lowered. There is.

The capacitance type detection device described in Patent Document 3 can detect a three-dimensional input operation, but assuming two types of input operation surfaces orthogonal to each other, at least one pair of input operation surfaces is provided for each input operation surface. It is necessary to arrange the detection electrode and the drive electrode of

In addition, this conventional electrostatic capacitance type detection device does not directly detect the electrostatic capacitance between the input operation body and the detection electrode to obtain the distance between the two, but each pair of detection by the presence of the input operation body Since the change in capacitance between the electrode and the drive electrode is not necessarily proportional to the distance between the input operation body and the detection electrode, the relative difference between the two indicates that the relative movement of the input operation body along the detection direction (input operation Motion) can not be detected up to the input operation position.

Furthermore, since the input operation is detected from the change in electrostatic capacitance between the detection electrode and the drive electrode arranged along the input operation surface, the detection accuracy drops sharply for the input operation away from the input operation surface. The three-dimensional input operation away from the plane in which the detection electrode and the drive electrode are disposed can not be detected.

The present invention has been made in consideration of such conventional problems, and provides a capacitive touch panel capable of detecting an input operation position of a non-contact input operation only approaching an input operation surface. The purpose is

Another object of the present invention is to provide a capacitive touch panel excellent in the visibility of the display disposed on the back side without disposing the transparent member on the input operation surface.

In addition, a capacitive touch panel capable of detecting an input operation position in the Z direction orthogonal to the XY direction parallel to the input operation surface can be provided only by arranging a limited number of detection electrodes around the input operation surface. The purpose is

In order to achieve the above-mentioned object, in the capacitive touch panel according to claim 1, a plurality of detection electrodes are disposed so as to be insulated from each other, and an arrangement position of each detection electrode, and electrostatics of each detection electrode and an input operation body A capacitive touch panel for detecting an input operation position of an input operation body from a capacitance, which comprises a plurality of detection electrodes arranged at predetermined intervals in an insulating case, an input operation body, and a plurality of detection electrodes. Signal detection means for detecting the reception level of the alternating current detection signal appearing on each detection electrode through the electrostatic capacitance between each detection electrode and the input operation body, Based on the reception level of the AC detection signal detected by each signal detection means for each detection electrode, the relative distance between the input operation body and the arrangement position of each detection electrode is compared to detect the input operation position of the input operation body Equipped with input position detection means Characterized in that was.

The electrostatic capacitance Cm between the detection electrode and the input operation body is d between the detection electrode and the input operation body, the dielectric constant of vacuum is ε ₀ , the relative permittivity of air ε is about 1, the input operation body and the detection electrode Let s be the opposing area of

The reception level Vi of the alternating current detection signal which is represented by the equation and is proportional to the capacitance Cm is inversely proportional to the distance d between the detection electrode and the input operation body.

The input position detection means compares the reception level Vi of the alternating current detection signal detected by the signal detection means for each detection electrode to obtain the distance between each detection electrode and the input operation body.

The output level Vs of the alternating current detection signal, the distance L in the detection direction between the pair of detection electrodes disposed along the detection direction of the input operation position, and the reception levels V0 and V1 of the alternating current detection signals appearing on the pair of respective detection electrodes If it is obtained, the input operation position along the detection direction and the input operation position in the direction orthogonal to the detection direction can be detected, and if a pair of detection electrodes are arranged in the XY directions orthogonal to each other, the XY direction and the XY plane It is possible to detect a three-dimensional input operation position in the Z direction orthogonal to.

In the electrostatic capacitance type touch panel according to claim 4, a pair of detection electrodes X0 and detection electrodes X1 formed in an elongated strip shape are disposed along the inner edges of the window holes formed in the insulating case facing each other in the X direction. The input position detection means compares the relative distance between the input operation body and the inner edge facing in the X direction based on the reception level of the alternating current detection signal detected from the detection electrode X0 and the detection electrode X1. To detect an input operation position x in the X direction with the input operation surface.

Since a pair of detection electrodes X0 and detection electrodes X1 formed in an elongated strip shape are disposed along the inner edges facing in the X direction of the window holes formed in the insulating case, both detection electrodes X0 and detection electrodes X1 are on both sides In the input operation to the plane of the window hole arranged in the, the input operation position is located on the straight line connecting the detection electrode X0 and the detection electrode X1 in the X direction.

The distance between the detection electrode X0 and the detection electrode X1 facing in the X direction of the window hole is Lx, the reception level of the detection electrode X0 is Vx0, the reception level of the detection electrode X1 is Vx1, the distance d between the detection electrode and the input operator Assuming that the proportional constant of the reception level Vx1 that is inversely proportional to is k, from the detection electrode X0 to the detection electrode X1 when the input operation is performed on the input operation surface in the window hole in which the pair of detection electrodes X0 and detection electrodes X1 face each other The input operation position x in the X direction is

The input position detection unit detects the input operation position x in the X direction from the known distance Lx and the reception levels Vx0 and Vx1 detected by the signal detection unit.

In the capacitive touch panel according to claim 5, a pair of detection electrodes Y0 and detection electrodes Y1 formed in a strip shape respectively are disposed along the inner edges of the window holes orthogonal to the X direction in the Y direction, The input position detection means compares the relative distance between the input operating body and the inner edge facing in the Y direction based on the reception level of the AC detection signal detected from the detection electrode Y0 and the detection electrode Y1, and An input operation position y in the Y direction, which is an input operation surface, is detected.

Since a pair of detection electrodes Y0 and detection electrodes Y1 formed in an elongated strip shape are disposed along the inner edges facing in the Y direction of the window holes formed in the insulating case, both detection electrodes Y0 and detection electrodes Y1 are on both sides. In the input operation to the plane of the window hole arranged in the above, the input operation position is located on the straight line connecting the detection electrode Y0 and the detection electrode Y1 in the Y direction.

The distance between the detection electrode Y0 and the detection electrode Y1 facing in the Y direction of the window hole is Ly, the reception level of the detection electrode Y0 is Vy0, the reception level of the detection electrode Y1 is Vy1, and the distance d between the detection electrode and the input operator Assuming that the proportional constant of the reception level Vy1 is inversely proportional to k, from the detection electrode Y0 to the detection electrode Y1 when the input operation is performed on the input operation surface in the window hole in which the pair of detection electrodes Y0 and the detection electrode Y1 face each other. The input operation position y in the Y-direction is

The input position detection means detects the input operation position y in the Y direction from the known distance Ly and the reception levels Vy0 and Vy1 detected by the signal detection means.

In the capacitive touch panel according to claim 9, the window hole is formed in a rectangular shape, one of the pair of detection electrodes opposed by the window hole is a reference detection electrode, the other is an opposite detection electrode, and the input position detection means The distance L in the opposite direction between the pair of detection electrodes, the output level Vs of the alternating current detection signal between the pair of detection electrodes and the input operation body, and the alternating current detection signal detected from the reference detection electrode and the opposite detection electrode The input operation position r in the opposite direction from the reference detection electrode to the opposite detection electrode is detected from the reception levels V0 and V1, and the input operation position z in the Z direction orthogonal to the plane of the window is detected. It is characterized by

Assuming that the distance between the reference detection electrode and the input operation position along the opposite direction is r,

From the equation (2), the input operation position r in the detection direction and the input operation position z in the Z direction are obtained.

In the capacitive touch panel according to claim 12, a plurality of divided detection electrodes each formed in an elongated strip shape are disposed so as to be mutually insulated along the inner edge of the window hole parallel to the X direction or the Y direction. The detection means compares the reception levels of the alternating current detection signals detected from the divided detection electrodes, and X along the arrangement direction of the divided detection electrodes from the arrangement position of the divided detection electrodes at which the maximum reception level is detected. The input operation position in the direction or Y direction is detected.

Since the capacitance Cm between the divided detection electrode closest to the input operation body and the input operation body is maximum as compared with the other divided detection electrodes, the maximum reception level of the AC detection signal is detected. Therefore, the input operation position in the arrangement direction can be detected only by the detection electrodes arranged in one direction along the inner edge of the window hole.

If another detection electrode is arranged at the inner edge opposed to the divided detection electrode through the window hole, the input operation position in the opposite direction orthogonal to the arrangement direction can be detected, and the detection electrode is arranged at a pair of opposite inner edges of the window hole. Only by this, it is possible to detect the input operation position in the X and Y directions with the opening surface of the window hole as the input operation surface.

In the electrostatic capacitance type touch panel according to claim 3, claim 11, claim 11 and claim 14, a conductive layer covering the entire back side of the window hole and the plurality of detection electrodes is laminated on the back side of the insulating case It is characterized by

If the conductive layer is grounded, the back side of the input operation body and the detection electrode is shielded by the conductive layer, and therefore, the input operation body is not easily affected by stray capacitance due to a conductor such as a surrounding wiring pattern or an electronic component. Capacitance between detection electrodes can be accurately detected.

In addition, if monitoring means is provided to monitor the potential of the conductive layer and detect potential fluctuations due to the contact between the input operating body and the conductive layer, the input operation itself which touches the input operating body to the conductive layer separately from the detection of the input operation position is also It can be detected.

In the capacitive touch panel according to the second aspect, the sixth aspect, the tenth aspect, and the thirteenth aspect, the signal detection means makes the alternating current detection signal appearing on each of the detection electrodes more than the cycle of the alternating current detection signal. It is characterized in that it has an integration circuit that integrates over a long time, and uses the output level of the integration circuit as a reception level.

Since the AC detection signal appearing on the detection electrode according to the small capacitance between the input operation body and the detection electrode is integrated in a time sufficiently longer than the cycle of the AC detection signal, the signal detection means The input operation position can be detected from the reception level of the detection signal.

According to the first aspect of the present invention, it is possible to detect an input operation position of a non-contact input operation that only causes an input operation body such as a finger to approach the input operation surface.

In addition to the input operation position in the X and Y directions parallel to the input operation surface, the input operation position in the Z direction orthogonal to the input operation surface is detected only by arranging a limited number of detection electrodes around the input operation surface. it can.

According to the invention of claim 4, the input operation position in the X direction is detected without disposing the touch member made of a transparent electrode or a transparent dielectric on the input operation surface with the opening surface of the window hole of the insulating case as the input operation surface. It is possible to directly view the display disposed on the back side without interposing the transparent member.

In addition, since there is no transparent member in contact with the input operation body, there is no problem that the input operation body such as a finger is touched and the transparent member becomes dirty and the display becomes difficult to see.

According to the invention of claim 5, with the opening surface of the window hole of the insulating case as the input operation surface, the XY along the input operation surface without disposing the touch member made of the transparent electrode or the transparent dielectric on the input operation surface. The position input operation direction can be detected, and the display disposed on the back side can be directly viewed without interposing the transparent member.

In addition, even if it is a non-contact input operation for inserting an input operation body such as a finger into the window hole only by using four elongated detection electrodes, a two-dimensional input operation position in the XY direction Can be detected.

According to the invention of claim 9, the input operation position in the detection direction along the input operation surface and the input operation position in the direction orthogonal to the input operation surface can be detected with the window hole of the insulating case as the input operation surface.

In addition, even if it is a non-contact input operation that inserts an input operation object such as a finger into the window hole simply by arranging along the inner edge of the four elongated rectangular rectangular window holes, the window The three-dimensional input operation position of the XY direction input position along the plane of the hole and the input position in the Z direction orthogonal to the plane of the window can be detected. Therefore, the input operation itself in the direction orthogonal to the input operation surface can be detected from the input operation position changing in the Z direction with the elapsed time. For example, the operation for accelerating the input operation body to approach the input operation surface is It can be recognized as an input operation equivalent to clicking.

According to the invention of claim 12, the input operation position along the arrangement direction of the divided detection electrodes can be detected without arranging the pair of detection electrodes along the opposing inner edge by the window hole, and the divided detection electrodes and the window If another detection electrode is arranged at the opposing inner edge through the hole, only by arranging the detection electrode at the pair of opposing inner edges of the window, input operation in the X and Y directions with the opening surface of the window as the input operation surface The position can be detected.

According to the inventions of claim 3, claim 11, claim 11 and claim 14, by grounding the conductive layer, the reception level of the alternating current detection signal, which decreases in proportion to the distance between the input operating body and the detection electrode, can be obtained. And can be detected more accurately without the influence of surrounding conductors.

In addition, by providing monitoring means for monitoring the potential of the conductive layer, it is possible to detect an input operation in which the input operation body is touched on the conductive layer.

According to the inventions of claim 2, claim 6, claim 8, claim 10, claim 13, the reception level of the alternating current detection signal in which the micro capacitance of about 30 fF between the input operation body and the detection electrode is expanded. It is possible to detect the distance from the input operation body approaching the detection electrode in a non-contact manner without interposing a contact member with a high dielectric constant.

It is a top view of electric capacity type touch panel 1 concerning a 1st embodiment of the present invention. It is the sectional view on the AA line of FIG. FIG. 2 is a block diagram showing a capacitive touch panel 1; FIG. 2 is an equivalent circuit diagram of a power supply circuit of the capacitive touch panel 1; FIG. 4 is a circuit diagram showing details of a signal detection circuit 13 and an integration processing circuit 14 of FIG. 3; FIG. 2 is an equivalent circuit diagram of a signal detection circuit unit of the capacitive touch panel 1; It is a voltage waveform figure of each part shown to (a) (b) (c) of FIG. It is a top view of electric capacity type touch panel 50 concerning a 2nd embodiment of the present invention. It is a top view of electric capacity type touch panel 51 concerning a 3rd embodiment of the present invention. It is a top view of electric capacity type touch panel 52 concerning a 4th embodiment of the present invention.

Hereinafter, a capacitive touch panel (hereinafter referred to as a touch panel) 1 according to a first embodiment of the present invention will be described using FIGS. 1 to 7. The touch panel 1 has a rectangular frame-shaped insulating case 20 as shown in FIG. 1 so that a horizontally long rectangular window hole 21 is formed on the inside, and the opening face of the window hole 21 is a finger as an input operation body An input operation surface 21a is used to make an input operation by bringing 30 closer. The inner edge 20a of the insulating case 20 adjacent to the window hole 21 is an inclined surface which inclines downward toward the center of the window hole 21 as shown in FIG. 2, and the surface of the inner edge 20a of four sides orthogonal to each other In addition, a pair of detection electrodes Y0 and Y1 facing each other in the X direction and a pair of detection electrodes X0 and X1 facing each other in the X direction are integrally attached.

Each of the detection electrodes 11 (X0, X1, Y0, Y1) is formed in a strip shape, and is disposed substantially all along the attached inner edge 20a. Thereby, the finger 30 faces all the detection electrodes 11 regardless of the position of the input operation surface 21 a. Here, by arranging each detection electrode 11 along the inclined inner edge 20a, when the finger 30 is arranged above the input operation surface 21a, the opposing area with the finger 30 is maximized, and the electrostatic described later will be described. The capacitance Cm is prevented from becoming a small value.

As shown in FIG. 3, main circuit components constituting the touch panel 1 including the detection electrodes 11 are separately mounted on two types of non-vibration side circuit boards 2 and vibration side circuit boards 3. A reference power supply circuit 4 consisting of a low voltage reference power supply line GND and a high voltage reference power supply line VCC at the ground potential is wired to the non-oscillating circuit board 2, and a DC voltage Vcc is applied between the low voltage reference power supply line GND and the high voltage reference power supply line VCC. The DC power source 5 for applying the voltage is connected. Thus, each circuit component such as the interface circuit 6 mounted on the non-oscillating circuit board 2 is connected to the reference power supply circuit 4 and driven by the output voltage Vcc of the DC power supply 5.

Further, on the vibration side circuit board 3, a vibration power supply circuit 7 including a low voltage vibration power supply line SGND and a high voltage vibration power supply line SVCC is wired. The low voltage oscillating power supply line SGND is connected to the low voltage reference power supply line GND, and the high voltage oscillating power supply line SVCC is connected to the high voltage reference power supply line VCC via the coils 8 and 9, respectively. The inductances of the coil 8 and the coil 9 are both set to high impedance values with respect to an alternating current detection signal SG of the natural frequency f described later, and in this case, coils 8 and 9 of the same inductance L are used.

The oscillation circuit 15 serving as a transmission means for transmitting the natural frequency f of the AC detection signal SG is mounted on the vibration-side circuit board 3 and is branched via a bifurcated capacitance C 'via capacitors 17 and 18 for blocking the DC voltage. Thus, the AC detection signal SG is connected to the low voltage reference power supply line GND of the reference power supply circuit 4 and the high voltage reference power supply line VCC. Thus, as shown in FIG. 3, when the AC detection signal SG of the natural frequency f is synchronized and output to the low voltage reference power supply line GND of the reference power supply circuit 4 and the high voltage reference power supply line VCC Since the power supply line GND is grounded and is at a stable potential, the potentials of the low voltage oscillating power supply line SGND and the high voltage oscillating power supply line SVCC of the oscillating power supply circuit 7 are synchronized and fluctuate at the natural frequency f The same DC output voltage Vcc as that of the power supply circuit 4 is obtained. The natural frequency f of the alternating current detection signal SG can be adjusted arbitrarily, but here, an alternating current detection signal SG of a natural oscillation frequency of 187 kHz is output.

When AC detection signal SG of natural frequency f flows to reference power supply circuit 4 and oscillating power supply circuit 7, proximity between low voltage reference power supply line GND and high voltage reference power supply line VCC and between low voltage oscillating power supply line SGND and high voltage oscillating power supply line SVCC It is considered that these power supply lines are short-circuited in the band of the natural frequency f, and the reference power supply circuit 4 and the oscillating power supply circuit 7 are shown in the equivalent circuit diagram of FIG.

As shown in FIG. 4, capacitors 17 and 18 having a capacitance C 'are connected in parallel between the output of the oscillating circuit 15 on the oscillating power supply 7 side and the reference power supply circuit 4. Therefore, the combined capacitance is 2C The combined inductance of the coils 8 and 9 connected in parallel between the reference power supply circuit 4 and the oscillating power supply circuit 7 is L / 2. These capacitors and inductors are connected in series in a closed circuit in which an alternating current detection signal SG of a natural frequency f flows, and the amplitude (level) of the alternating current detection signal SG is Vsg. Reference power supply circuit 4 at both ends of the coils 8 and 9 and oscillating power supply Assuming that the voltage between the circuits 7 is Vs, and the angular velocity represented by 2πf is ω (rad / sec),

Is represented by
Here, the circuit shown in FIG. 3 performs series resonance at ω ² LC ′ = 1, and the frequency f _{0 at} that time is

It becomes.

That is, assuming that the resonance frequency f ₀ obtained from the relation of the equation (2) is the natural frequency f of the alternating current detection signal SG, the vibration power supply circuit 7 is theoretically calculated from the equation (1) with respect to the level of the alternating current detection signal SG. The potential of the detection electrode 11 oscillates at infinity, and the potential of each detection electrode 11 connected to the oscillating power supply circuit 7 can also oscillate at infinity. The actual touch panel 1 does not resonate at the frequency f ₀ obtained from the equation (2) due to the influence of the inductances and stray capacitances of the reference power supply circuit 4 and the vibration power supply circuit 7, and the reference power supply circuit 4 and the vibration power supply circuit 7 The vibration power supply circuit 7 vibrates at an amplitude Vs expanded to a finite magnification with respect to the level Vsg of the AC detection signal SG due to an energy loss or the like when the AC detection signal SG flows.

Furthermore, since a large voltage can not be applied to each detection electrode 11 to which the operator's finger 30 may touch, the natural frequency f of the AC detection signal SG is adjusted in the vicinity of the resonance frequency f ₀ and each detection electrode 11 The output level Vs of the alternating current detection signal SG oscillating relatively is set arbitrarily, and here, the output level Vs is 5V.

Also, the natural frequency f of the AC detection signal SG can be set to any frequency, but the common operating noise of the frequency of the commercial AC power is not the constant potential of the input operating body 30 around the commercial AC power supply line. It is necessary to detect the alternating current detection signal SG of the natural frequency f from the detection electrodes 11 by discriminating it from the frequency of the commercial alternating current power source because it may be superimposed, and the frequency of the commercial alternating current power source and its harmonics are excluded. Is preferred.

Each of the detection electrodes 11 described above is connected to the high voltage oscillating power supply line SVCC, here, one of the low voltage oscillating power supply line SGND and the high voltage oscillating power supply line SVCC of the oscillating power supply circuit 7. By connecting all the detection electrodes 11 to the high voltage vibration power supply line SVCC, the operator's finger 30 vibrates at the output frequency Vs of the AC detection signal SG at the natural frequency f while part of the foot is grounded. Since the voltage of the output level Vs of the alternating current detection signal SG is generated between the two in the detection electrode 11 where the finger 30 approaches and the capacitance Cm with the finger 30 increases. An alternating current detection signal SG of a natural frequency f appears from the detection electrode 11 to the finger 30 via the capacitance Cm. If this is viewed from the vibration power supply circuit 7 vibrating at the natural frequency f, the finger 30 as the input operation body vibrates at the natural frequency f of the alternating current detection signal SG with respect to the detection electrode 11 of constant potential.

The capacitance Cm between each detection electrode 11 and the input operating body 30 is d between the distance between the detection electrode and the input operating body, ε ₀ for vacuum dielectric constant, approximately 1 for air relative dielectric constant ε, the input operating body the facing area 30 and the detection electrode 11 as s, represented by _{Cm = ε 0 · ε r ·} s / d, reactance Xc for the alternating-current detection signal of the electrostatic capacitance Cm is the natural frequency of the alternating-current detection signal at f Because there is

From

Is represented by

FIG. 6 is an equivalent circuit diagram of the entire signal detection circuit unit for detecting the reception level Vi of the AC detection signal SG appearing on the detection electrode 11. In the figure, Cp represents a floating between the detection electrode 11 and the low voltage oscillating power supply line SGND. The capacitance rp is the internal resistance value of the detection electrode 11, and R4 is the resistance value of the output resistance. In the equivalent circuit diagram in the figure,

From the equations (3) to (6),

Relationship is obtained.

Assuming that the internal resistance rp is 0, and R4 is connected to the integrating operational amplifier A / D 25 described later via the multiplexer 12, if it is infinite, the equation (7) is

Since the capacitance Cm is extremely small, such as several 10 fF, compared to the stray capacitance Cp of several 10 pF, equation (7) further

Is represented by

As described above, Cm of the input operation body 30 and the detection electrode 11 is

Since it is represented by, if this is substituted in equation (8) and deformed,

Therefore, assuming that the facing area s of the finger 30 and the detection electrode 11 does not substantially change during the input operation, (ε0 · εr · s / Cp) in the equation (9) is a constant. If k is given, the reception level Vi of the AC detection signal SG appearing on the detection electrode 11 is

Thus, as the detection electrode 11 is closer to the finger 30, the reception level Vi becomes a larger value closer to the output level Vs of the AC detection signal SG. However, when the finger 30 is close to the detection electrode 11 and the electrostatic capacitance Cm between the two is not large enough to be ignored compared to the stray capacitance Cp of several tens pF, the equation (10) can not be applied, and the reception level Vi Becomes the output level Vs at the maximum.

By using the equation (10), it is possible to compare the distance between the finger 30 and each detection electrode 11 by comparing the reception levels Vi of the AC detection signals appearing on each of the plurality of detection electrodes 11, and in the present embodiment From the arrangement position of each detection electrode 11 (X0, X1, Y0, Y1) and the reception level Vi of each detection electrode 11 (X0, X1, Y0, Y1), input in the XY direction parallel to the input operation surface 21a 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 21a is detected.

In order to detect the input operation position (x, y, z), as shown in FIG. 3, an analog multiplexer 12, a signal processing circuit 13, an integration processing circuit 14, and an A / D converter are provided on the vibration side circuit board 3. 19. Each circuit element of MPU (microprocessor unit) 10 and oscillating circuit 15 is mounted, and connected to low voltage oscillating power supply line SGND and high voltage oscillating power supply line SVCC of oscillating power supply circuit 7, and output voltage Vcc from DC power supply 5 Receiving and operating.

The analog multiplexer 12 switches and connects each detection electrode 11 to the signal processing circuit 13 in a fixed cycle, here every 200 msec, by switching control from the MPU 10, and sequentially processes the AC detection signal SG appearing on each detection electrode 11 It is output to the circuit 13.

As shown in FIG. 5, the signal processing circuit 13 includes a resonant circuit 23 for passing a signal in a frequency band centered on the natural frequency f of the AC detection signal, an amplification circuit 24 for impedance conversion, and a series between them. And a first analog switch ASW1 connected to the The resonance circuit 23 cuts low frequency components such as a DC signal and high frequency noise such as common mode noise from the signal appearing on the detection electrode 11 connected via the analog multiplexer 12, and amplifies only the AC detection signal SG in the latter stage amplification circuit Output to 24 The amplification circuit 24 is an impedance conversion element whose input impedance is close to infinity and whose output impedance is a minute value, and is an integration process connected to the output side of even a weak alternating current detection signal SG appearing on the detection electrode 11 The circuit 14 is made to operate.

The first analog switch ASW1 is open / close controlled by the MPU 10, and connects between the resonance circuit 23 and the amplification circuit 24 during an integration operation period (Tint) in which the integration processing circuit 14 performs integration operation described later, and offset adjustment described later Shut off during period (Tset). Thus, the AC detection signal SG is not output to the integration processing circuit 14 during the offset adjustment period (Tset).

As shown in FIG. 5, the integration processing circuit 14 includes an integration operational amplifier 25, an integration resistor R 1 connected between the output of the signal processing circuit 14 and the inverting input terminal of the integration operational amplifier 25, and an integration operational amplifier 25. The integration capacitor C1 connected between the inverting input terminal and the output terminal, and the second analog switch ASW2 connected in parallel to the integration capacitor C1 and whose opening and closing are controlled by the MPU 10 are provided.

The voltage of the AC detection signal input to the inverting input terminal of the integrating operational amplifier 25 via the integrating resistor R is Vin, the voltage output from the output terminal of the integrating operational amplifier 25 is Vout, and the resistance value of the integrating resistor R1 If R and the capacity of the integration capacitor C1 are C, then

The voltage Vout obtained by integrating the input voltage Vin is output from the output terminal of the integration operational amplifier 25.

The second analog switch ASW2 is closed by the MPU 10 for a short time after the start of the offset adjustment period (Tset), and charges accumulated in the integration capacitor C1 quickly during the integration operation period (Tint) of the integration processing circuit 14 The charging voltage which is discharged and charged in the integration capacitor C in the integration operation period (Tint) immediately before the discharge operation does not affect the offset operation of the offset adjustment period (Tset) of the integration processing circuit 14 described later.

There is an error of the DC component due to the offset voltage of the integrating operational amplifier 25 and other factors between the inverting input terminal and the noninverting input terminal of the integrating operational amplifier 25, and an error voltage obtained by combining these is represented by an offset voltage Δv. , (11),

Since the offset voltage Δv is a direct current component, equation (12) is

The error due to the offset voltage Δv in the output voltage Vout increases with the passage of time t.

Therefore, in the present embodiment, the integration processing circuit 14 is further provided with a feedback circuit unit in order to substantially eliminate the influence of the offset voltage Δv. As shown in FIG. 5, this feedback circuit section includes a feedback operational amplifier 26, a third analog switch ASW3 connected between the output of the feedback operational amplifier 26 and the noninverting input terminal of the integration operational amplifier 25, and a third analog It is connected between the switch ASW3 and the non-inversion input terminal of the integrating operational amplifier 25 and comprises a holding capacitor 27 charged with the output voltage of the feedback operational amplifier 26.

The inverting input terminal of the feedback operational amplifier 26 is connected to the output of the integrating operational amplifier 25 via the resistor R2, and the non-inverting input terminal is connected to the input side of the integrating resistor R1. The resistances of the resistors R3 and R2 connected between the inverting input terminal and the output terminal of the feedback operational amplifier 26 are equal, so that the feedback operational amplifier 26 is used for integration while the third analog switch ASW3 is closed and controlled. The input voltage Vin input to the inverting input terminal of the operational amplifier 25 is used as a reference potential, and the difference between the output voltage Vout of the integrating operational amplifier 25 with respect to the input voltage Vin is amplified by gain -1 and fed back to the noninverting input terminal of the integrating operational amplifier 25 Act as you do.

During the offset adjustment period (Tset) controlled by the MPU 10, the third analog switch ASW3 is closed and the input of the integration resistor R1 and each detection electrode 11 are cut off by the first analog switch ASW1 which is open controlled Thus, the potential of the inverting input terminal of the integrating operational amplifier 25 is maintained at a constant input voltage Vin without the AC detection signal SG being input to the input side of the integrating resistor R1.

Assuming that the offset voltage Δv is generated at the inverting input terminal with respect to the non-inverting input terminal of the integrating operational amplifier 25, the integral value − (Vin + Δv) · Δt / CR is output after Δt, but the feedback operational amplifier Since Vin + (Vin + Δv) · Δt / CR is input to the non-inverted input terminal of the integrating operational amplifier 25 and Δt / CR is sufficiently smaller than 1, the output of the integrating operational amplifier 25 is offset by repeating this. It converges to the voltage Δv and becomes stable. In this state, the potential obtained by adding the offset voltage Δv to the inverting input terminal of the integrating operational amplifier 25 becomes equal to the potential of the noninverting input terminal, and the holding capacitor 27 includes the noninverting input including the effect of the offset voltage Δv. A correction voltage is charged so that the differential voltage between the terminal and the inverting input terminal is zero. Therefore, the offset adjustment period (Tset) is set to a time sufficient for the output Vout of the integrating operational amplifier 25 to reach and stabilize the offset voltage Δv, and the holding capacitor 27 is used when the output Vout of the integrating operational amplifier 25 is stabilized. The capacitor of the capacitor which saturates is used for.

After the offset adjustment period (Tset) has elapsed, the MPU 10 controls to close the first analog switch ASW1 and opens the third analog switch ASW3 to shift to an integration operation period (Tint). During the integration operation period (Tint), by controlling the first analog switch ASW1 to be closed, the AC detection signal SG appearing on the detection electrode 11 selected and connected by the analog multiplexer 12 is integrated via the integration resistor R1. It is input to the inverting input terminal. Further, since the third analog switch ASW3 is controlled to be opened, the correction voltage charged in the hold capacitor 27 is input to the non-inversion input terminal of the integration operational amplifier 25 during the offset adjustment period (Tset), and the offset voltage is The differential voltage between the noninverting input terminal of the integrating operational amplifier 25 including Δv and the inverting input terminal excluding the AC detection signal SG becomes 0, and the offset voltage Δv shown in equation (13) is output to the output Vout of the integrating operational amplifier 25. It does not include the integrated error -Δv · t / CR.

As a result, only the voltage Vin of the minute AC detection signal SG is integrated and expanded, and appears as the output Vout of the integration operational amplifier 25. The MPU 10 is at the determination time t1 at the determination time t1 immediately before the end of the integration operation period (Tint) after the same time elapses in each integration operation period (Tint) from the start of the integration operation period (Tint). The output Vout is output to the A / D converter 19 connected to the subsequent stage. The integration operation period (Tint) is sufficiently shorter than the saturation time of the integration capacitor C1 determined by CR, and the voltage Vin of the AC detection signal SG is determined from the output Vout of the integration operational amplifier 25 which is its integral value at t1. Set to a distinguishable period.

The A / D converter 19 quantizes the output Vout of the integration operational amplifier 25 at t1 and outputs the result to the MPU 10.

The quantization data output from the A / D converter 19 represents the reception level Vi of the AC detection signal SG appearing on each detection electrode 11 selected and connected to the analog multiplexer 12 during the integration operation period (Tint), and the input position detection The MPU 10 acting as a means detects the input operation position of the finger 30 from the reception level Vi of the AC detection signal SG appearing on each detection electrode 11. When the reception level Vi of the AC detection signal SG is amplified to n times the reception level Vi through the signal processing circuit 13 and the integration circuit 14, the MPU 10 outputs the quantum output from the A / D converter 19. The input operation position is calculated from the reception level Vi where the conversion data is 1 / n.

When the detection electrodes X0 and X1 are connected to the analog multiplexer 12, the reception level Vi of the AC detection signal SG output from the A / D converter 19 is Vx0, Vx1, and a pair of detection electrodes X0 facing in the X direction. Assuming that the distance between X1 is Lx and the finger 30 is at the input operation position P (x, z) shown in FIG.
About the detection electrode X0

And the detection electrode X1,

Since k, Lx, and Vs are known values, substituting the detected Vx0 and Vx1 into the equations (14) and (15), the condition that Lx−x, z is not negative,
The position x in the X direction from the detection electrode X0 and the position z in the Z direction orthogonal to the input operation surface 21a are obtained.

When it is difficult to detect the output level Vs of the AC detection signal SG, for example, reception of the AC detection signal SG for the detection electrode X1 at the input operation position (x (0), z (0)) of the detection electrode X0 Detect the level Vx1 (0, 0) and substitute it into the equation (10),

It may be obtained from

Similarly, in the Y direction, when the detection electrodes Y0 and Y1 are connected to the analog multiplexer 12, the reception level Vi of the AC detection signal SG output from the A / D converter 19 is opposite in the Vy0, Vy1, and Y directions, respectively. Assuming that the distance between the pair of detection electrodes Y0 and Y1 to be set is Ly and the finger 30 is at the input operation position P (y, z), from Expression (10),
About the detection electrode Y0

And the detection electrode Y1,

From the condition that Ly-y, z is not negative, substituting the detected Vy0, Vy1 into the equations (16) and (17).
The position y in the Y direction from the detection electrode Y0 and the position z in the Z direction orthogonal to the input operation surface 21a are obtained.

Each of the detection electrodes X0, X1, Y0, Y1 is disposed over the entire side of the inner edge of the rectangular window hole 21. Therefore, the finger on which at least one of the input operation surface 21a in the vertical direction is input operated 30 face the detection electrodes X0 and X1 in the X direction and the detection electrodes Y0 and Y1 in the Y direction, and from the expressions (14) to (17), the three-dimensional input operation position (x, y, z) can be detected.

In particular, in the case of using the touch panel 1 for detecting a two-dimensional input operation position (x, y) only for the input operation on the input operation surface 21a, the equation (14) and z 15), if the output level Vs is eliminated, 0 ≦ x ≦ Lx

, And solving equation (18) for x,

It becomes.

Similarly, for the Y direction, from Eqs. (16) and (17),

The input positions (x, y) in the X and Y directions on the input operation surface 21a can be easily obtained from Vx0, Vx1, Vy0 and Vy1.

Input operation data including the input operation position (x, y, z) detected by the MPU 10 is output to the interface circuit 6 mounted on the non-oscillating circuit board 2 through the signal line 16 in which the direct current is isolated It is output from the circuit 6 to a host device using input operation data by USB communication, I ² C communication or the like.

Hereinafter, an operation of detecting the input operation position (x, y, z) of the finger 30 by the touch panel 1 configured as described above will be described. The electrostatic capacitance Cm between the finger 30 and the detection electrode 11 when the input operation is performed at a position 10 cm away from the detection electrode 11 as the input operation body is the facing area s between the finger 30 and the detection electrode 11 the ^{5 · 10 -4 (m 2)} , a dielectric constant ε0 of ^{vacuum, 8.854 · 10 -12 (F /} m), as about 1 ε dielectric constant of air, about 44.27 ^{· 10 -15} The value F is extremely small, ie 44.27 fF.

At this time, the reception level Vi of the alternating current detection signal SG appearing on the detection electrode 11 is 1.13, where the proportional constant k is Cp / (ε0 · εr · s) and the stray capacitance Cp is 50 pF in the equation (10). since 10 ^4, the output level Vs of the AC detection signal SG 5V, and to the the ^{10 -1} d, it is about 4.4MV, expanding this in integral processing circuit 14 calculates the distance d.

While detecting the input operation position, the MPU 19 switches and controls the connection of the analog multiplexer 12 in a cycle of about 200 msec shown in FIG. 6, and detects each detection electrode 11 in the order of detection electrodes X0, X1, Y0, Y1. , And one cycle of switching and connecting all the detection electrodes X0, X1, Y0, Y1 is repeated. One period connected to the signal processing circuit 13 for each detection electrode 11 includes the offset adjustment period Tset and the integration operation period Tint, and the MPU 19 performs the second period for a predetermined period immediately after the start of the offset adjustment period Tset as described above. The analog switch ASW2 is closed, and the charge accumulated in the integration capacitor C1 is discharged during the integration operation period Tint immediately before that.

During the offset adjustment period Tset, the first analog switch ASW1 is controlled to open and the third analog switch ASW3 is closed, whereby the output voltage Vo ·· (c) of the integration operational amplifier 25 is controlled to open ASW1 and is constant. Offset voltage of the integration operational amplifier 25 at the end of the offset adjustment period Tset, which converges and stabilizes on the potential at the potential difference between the input voltage (a) of the inverting input terminal and the offset voltage Δv. A charge voltage that cancels Δv is charged to hold capacitor 27.

Subsequently, the MPU 19 performs control to close the first analog switch ASW1 and control to open the third analog switch ASW3 to shift to the integration operation period Tint. By controlling the first analog switch ASW1 to be closed, an AC detection signal SG that appears on the detection electrode 11 connected via the analog multiplexer 12 in that period is input from the signal processing circuit 13 to the integration processing circuit 14. Further, the third analog switch ASW3 is controlled to be opened, whereby the output of the feedback operational amplifier 26 is disconnected from the non-inverting input terminal of the integrating operational amplifier 25 and the charging voltage of the hold capacitor 27 is added. A charge voltage that cancels the offset voltage Δv is applied to the 25 non-inverting input terminals.

As shown in FIG. 7, during the integration operation period Tint, the charging voltage Δv ·· (b) of the hold capacitor 27 is input to the non-inverting input terminal of the integrating operational amplifier 25 and the inverting input with respect to the potential of (b) The difference from the voltage (a) of the AC detection signal SG of the natural frequency of 187 kHz input to the terminal is integrated at the elapsed time t, inverted, and output from the integration operational amplifier 25 (c). In the drawing, as the voltage of the alternating current detection signal SG input to the inverting input terminal increases, the slope of the output waveform of the integrating operational amplifier 25 appearing in a stepwise manner increases.

In this embodiment, a determination time t1 is set immediately before the end of the integration operation period Tint and when the elapsed time Tc from the start of the integration operation period Tint is the same as the connection time with each detection electrode 11, The output of the integration operational amplifier 25 at time t1 is output to the A / D converter 19 as the reception levels Vx0, Vx1, Vy0 and Vy1 of the AC detection signal SG appearing on the connected detection electrode 11.

After completion of the integration operation period Tint, the MPU 10 switches and controls the analog multiplexer 12 so as to connect the next detection electrode 11 to the signal processing circuit 13. Similarly, for the detection electrode 11, the offset adjustment period Tset and the integration operation period Repeat control of Tint. The MPU 10 uses the reception levels Vx0, Vx1, Vy0, Vy1 input from the A / D converter 19 for each detection electrode 11 after one cycle of connecting all the detection electrodes X0, X1, Y0, Y1. The three-dimensional input operation position (x, y, z) of the finger 30 is detected using the equations (14) to (17). Further, in the case of using the touch panel 1 for detecting the input operation position (x, y) of the finger 30 on the input operation surface 21a, the two-dimensional input operation position (x, y) is obtained from the equations (19) and (20). ) To detect.

The detected input operation position (x, y) or the input operation position (x, y, z) is output to the upper device using the touch panel 1 as an input device as input operation data via the interface circuit 6 at any timing. Ru.

In the touch panel 1 according to the first embodiment, a pair of detection electrodes X0 and X1 or a pair of detection electrodes Y0 and Y1 are disposed in the opposing direction facing each other in the rectangular window holes 21, and the input position in the opposing direction However, as shown in FIGS. 8 to 10, a plurality of divided detection electrodes 41 are arranged along the detection direction, and the reception level Vi of the alternating current detection signal SG similarly detected for each of the divided detection electrodes 41 is compared. Then, the input operation position in the detection direction may be detected. The touch panels 50, 51 and 52 according to the other embodiments shown in FIGS. 8 to 10 will be different from the first embodiment in the drawings only in the configuration of the detection electrodes. The explanation is omitted.

FIG. 8 is a plan view of the capacitive touch panel 50 according to the second embodiment in which four types of detection electrodes X0, X1, Y0, and Y1 of the touch panel 1 are configured by a plurality of divided detection electrodes 41, respectively. . That is, instead of the detection electrodes X0, a plurality of split detection electrodes _{X0 1, X0} 2 ·· _{X0 n} is, instead of the detection electrode X1, a plurality of split detection electrode _{X1 1, X1} 2 ·· _{X1 n} is the detection electrode instead of Y0, a plurality of split detection electrodes _{Y0 1, Y0} 2 ·· _{Y0 n} is, instead of the detection electrode Y1, the arrangement of the plurality of split detection electrodes _{Y1 1, Y1} 2 ·· _{Y1 n} is the respective detection electrodes 11 respectively Arranged along the position.

The MPU 10 controls the multiplexer 12 to sequentially connect all the divided detection electrodes 41 to the signal processing circuit 13, and detects the reception level Vi of the alternating current detection signal SG appearing on the divided detection electrodes 41 connected during each connection period. Assuming that the finger 30 is input to the position shown, among the plurality of divided detection electrodes 41 arranged in a line in the same direction, the divided detection electrodes X0max, X1max, Y0max, Y1max arranged in the XY direction of the input operation position. The reception level Vi of is maximized, so that the input operation position (x, y) can be detected by relatively comparing the reception levels Vi of the divided detection electrodes 41 arranged in a line.

Further, the sum of the reception levels Vi of the plurality of divided detection electrodes 41 arranged in a line in the same direction corresponds to the reception level Vi of the detection electrodes 11 according to the first embodiment arranged at the same position. The input position in the opposite direction or the input position in the Z direction orthogonal to the opposite direction can also be detected, as compared with the sum of the reception levels Vi of the divided detection electrodes arranged opposite to each other.

FIG. 9 is a plan view of the capacitive touch panel 51 according to the third embodiment in which the detection electrodes Y0 and Y1 opposed to each other in the Y direction of the touch panel 1 are configured by a plurality of divided detection electrodes 41, respectively. That is, the detection electrodes X0, X1 is the same as the first embodiment, in place of the detecting electrodes Y0, a plurality of split detection electrodes _{Y0 1, Y0} 2 ·· _{Y0 n} is, instead of the detection electrode Y1, a plurality of split detection electrodes _{Y1 1, Y1} 2 ·· _{Y1 n} are those which are arranged along the arrangement positions of the detection electrodes 11, respectively.

The multiplexer 12 sequentially connects the detection electrodes X0 and X1 and all the divided detection electrodes 41 to the signal processing circuit 13, and detects the reception level Vi of the AC detection signal SG appearing on the detection electrodes 11 and 41 connected during each connection period. Do. MPU10 is a split detection electrodes _{Y0 1, Y0} 2 ·· _{Y0 n} sum Vsy0 reception level Vi of, as a reception level Vy0 detection electrodes Y0, split detection electrodes _{Y1 1, Y1} 2 ·· _{Y1 n} of the reception level Vi of The input operation position (y, z) in the Y direction and the Z direction is detected from Vsy0 and Vsy1 with the sum Vsy1 as the reception level Vy1 of the detection electrode Y1.

Also, the input operation position (x) in the X direction can be detected from the reception level Vx0 of the detection electrode X0 and the reception level Vx1 of the detection electrode X1 as in the first embodiment, but the second embodiment described above In the same manner as the detection in the above embodiment, the reception level Vi of the divided detection electrodes 41 arranged in a line in the same direction is relatively compared, and the position at which the maximum reception level Vi is detected in the X direction is the input operation position in the X direction. It can also be detected as (x).

As described above, in the case where at least one of the pair of detection electrodes 11 opposed in the first detection direction is a plurality of divided detection electrodes 41, the detection electrodes 11 in the second detection direction orthogonal to the first detection direction. The input operation position in the second detection direction can be detected without arranging. FIG. 10 shows a capacitive touch panel 52 in which the detection electrodes X0 and X1 overlapping the detection of the input operation position (x) in the X direction are omitted in the touch panel 51 shown in FIG.

According to the touch panel 52, the split detection electrodes _{Y0 1, Y0} 2 ·· _{Y0 n} reception level split detection electrodes _Y1 1 the sum Vsy0 of Vi _of, Y1 2 · · Y1 _n sum of the reception levels Vi of Vsy1, Y-direction an input operation position in the Z direction (y, z) and detects the, split detection electrodes _Y0 1 arranged on the same _level, Y0 2 · · Y0 _n or split detection electrodes _{Y1 1, Y1} 2 ·· _{Y1 n} reception level Relatively compare Vi to detect the input operation position (x) in the X direction.

In each of the embodiments described above, since the inside of the window hole 21 to be the input operation surface 21a is a space, the visibility of the display disposed below the space is excellent, but it is not necessary to be the space. For example, a conductive sheet on which a conductive layer formed of a transparent material is formed is disposed on the entire back surface of the detection electrodes 11 and 41 including the window holes 21 and equipotential to the detection electrodes 11 and 41 such as the low voltage vibration power supply line SGND. If the shield layer is connected to the ground wire which is to be used, external noise does not intrude into the detection electrodes 11 and 41, and stray capacitance does not fluctuate unstablely, and the input operation position can be detected more accurately. .

In addition, a conductive sheet having a potential different from that of the input operation body 30 is bridged to a position where the input operation body 30 in the window 21 serving as the input operation surface 21a can contact, and monitoring means for monitoring the potential of the conductive sheet is provided. For example, an input operation of touching the input operation body 30 to the conductive sheet can be detected from the potential fluctuation of the conductive sheet. Therefore, if a potential monitoring means is provided on the conductive sheet acting as the shield layer, it can also be used to detect an input operation.

In the above embodiment, the detection electrodes 11 and 41 are vibrated at the output level Vs of the AC detection signal SG with respect to the input operation body 30, and the relative potential of the output level Vs is generated between them. The potential of the input operation body 30 may be varied at the output level Vs of the AC detection signal SG with the potentials 11 and 41 as a constant potential.

Further, although the input operation body 30 has been described using the finger 30 with which the operator performs an input operation, the input operation body 30 may be an operation body different from the operator, such as a dedicated input pen held by the operator.

Moreover, the window hole formed in the rectangular outline can be made into any shape, and the detection electrodes are arranged at four corners of the window hole, for example, without arranging along the inner edge thereof. The input operation position in the window may be detected from the distance to each detection electrode.

Since the detection electrode has a large capacitance Cm between the detection electrodes in proportion to the area facing the input operation body and detection of the capacitance Cm is easy, the three-dimensional input operation position (x, x) on the input operation surface 21a In the above embodiment which also detects y and z), the detection electrode 11 is disposed along the inclined inner edge 20a of the insulating case 20, but the two-dimensional input operation position (x, x) on the input operation surface 21a When only y) is to be detected, it is desirable to arrange the detection electrode 11 along a vertical plane orthogonal to the input operation surface 21a, and the input operation in the Z direction mainly away from the input operation surface 21a in the vertical direction When detecting the position (z), it is desirable to arrange more horizontally.

The present invention is suitable for a capacitive touch panel in which a display element is disposed on the back side and detects an input operation without contact.

1, 50, 51, 52 Capacitive touch panel 10 MPU (input position detection means)
11 detection electrode 14 integration processing circuit (signal detection means)
15 Oscillator circuit (transmission means)
20a inner edge 21 window hole 21a input operation surface 30 finger (input operation body)
41 Division detection electrode Cm Capacitance SG AC detection signal Vs Output level of AC detection signal Vi Reception level of AC detection signal

Claims (14)

1. A capacitive touch panel that detects an input operation position of an input operation body, in which a plurality of detection electrodes are arranged so as to be isolated from each other, and the arrangement position of each detection electrode and the electrostatic capacitance between each detection electrode and the input operation body And
   A plurality of detection electrodes disposed in the insulating case at predetermined intervals;
   Transmitting means for transmitting an alternating current detection signal in which the relative potential between the input operation body and each of the plurality of detection electrodes fluctuates;
   Signal detection means for detecting the reception level of the alternating current detection signal appearing on each of the detection electrodes via the capacitance between each of the detection electrodes and the input operation body;
   Based on the reception level of the alternating current detection signal detected by each of the detection electrodes, the signal detection means compares the relative distance between the input operation body and the arrangement position of each of the detection electrodes and determines the input operation position of the input operation body What is claimed is: 1. A capacitive touch panel comprising: input position detection means for detecting an electric potential.
2. The signal detection means has an integration circuit that integrates the AC detection signal appearing on each of the detection electrodes in a time sufficiently longer than the cycle of the AC detection signal, and uses the output level of the integration circuit as a reception level. The capacitive touch panel according to item 1.
3. The electrostatic capacitance type touch panel according to claim 1 or 2, wherein a conductive layer covering the entire back side of the window hole and the plurality of detection electrodes is laminated on the back side of the insulating case.
4. A pair of detection electrodes X0 and detection electrodes X1 each formed in an elongated strip shape are disposed along the inner edges opposite to each other in the X direction of the window holes formed in the insulating case,
   The input position detection means compares the relative distance between the input operation body and the inner edge facing in the X direction based on the reception level of the AC detection signal detected from the detection electrode X0 and the detection electrode X1, and the opening of the window hole 2. The capacitive touch panel according to claim 1, wherein an input operation position x in the X direction with the surface as the input operation surface is detected.
5. A pair of detection electrodes Y0 and detection electrodes Y1 each formed in an elongated strip shape are disposed along the inner edges of the window holes in the Y direction opposite to each other orthogonal to the X direction,
   The input position detection means compares the relative distance between the input operation body and the inner edge facing in the Y direction based on the reception level of the alternating current detection signal detected from the detection electrode Y0 and the detection electrode Y1, and opens the window hole. 5. The capacitive touch panel according to claim 4, wherein an input operation position y in the Y direction having a surface as an input operation surface is detected.
6. The signal detection means has an integration circuit that integrates the AC detection signal appearing on each of the detection electrodes in a time sufficiently longer than the cycle of the AC detection signal, and uses the output level of the integration circuit as a reception level. The capacitive touch panel according to any one of Items 4 and 5.
7. The electrostatic capacitance type touch panel according to any one of claims 4 or 5, wherein a conductive layer covering the entire back side of the window hole and the plurality of detection electrodes is laminated on the back side of the insulating case.
8. The signal detection means has an integration circuit that integrates the AC detection signal appearing on each of the detection electrodes in a time sufficiently longer than the cycle of the AC detection signal, and uses the output level of the integration circuit as a reception level. The capacitive touch panel according to Item 7.
9. The window hole is formed in a rectangular shape,
   One of the pair of detection electrodes opposed by the window hole is a reference detection electrode, and the other is an opposite detection electrode.
   The input position detection means includes a distance L in the opposite direction between the pair of detection electrodes, an output level Vs of an alternating current detection signal between the pair of detection electrodes and the input operation body, the reference detection electrode and the opposite detection electrode Detecting the input operation position r in the opposite direction from the reference detection electrode to the opposite detection electrode from the reception levels V0 and V1 of the AC detection signal detected from the input, and the input in the Z direction orthogonal to the plane of the window The electrostatic capacitance type touch panel according to any one of claims 4 or 5, wherein the operation position z is detected.
10. The signal detection means has an integration circuit that integrates the AC detection signal appearing on each of the detection electrodes in a time sufficiently longer than the cycle of the AC detection signal, and uses the output level of the integration circuit as a reception level. The capacitive touch panel according to item 9.
11. 10. The capacitive touch panel according to claim 9, wherein a conductive layer covering the entire back side of the window hole and the plurality of detection electrodes is laminated on the back side of the insulating case.
12. A plurality of divided detection electrodes each formed in a strip shape are disposed so as to be mutually insulated along the inner edge of the window hole parallel to the X direction or the Y direction,
    The input position detection means compares the reception levels of the alternating current detection signals detected from the divided detection electrodes, and follows the arrangement direction of the divided detection electrodes from the arrangement position of the divided detection electrodes at which the maximum reception level is detected. The capacitive touch panel according to any one of claims 4 or 5, wherein the input operation position in the X direction or the Y direction is detected.
13. The signal detection means has an integration circuit that integrates the AC detection signal appearing on each of the detection electrodes in a time sufficiently longer than the cycle of the AC detection signal, and uses the output level of the integration circuit as a reception level. The capacitive touch panel according to Item 12.
14. The electrostatic capacitance type touch panel according to claim 12, wherein a conductive layer covering the entire back side of the window hole and the plurality of detection electrodes is laminated on the back side of the insulating case.

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