Contact detection device

Abstract

A contact detection device (10) in which an AC power supply (11) switches a first AC voltage and a second AC voltage having different frequencies and applies the voltages to a first electrode layer (22) and a second electrode layer (23), the contact detection device (10) being provided with: a storage unit (34) that stores an alternative quadrature phase component (QA) corresponding to a state in which a conductor is in contact with an electrostatic sensor (7); a quadrature phase component comparison unit (31) that compares a first quadrature phase component (Q1) extracted when the first AC voltage is applied to the second electrode layer (23) and a second quadrature phase component (Q2) extracted when the second AC voltage is applied to the second electrode layer (23); and a contact determination unit (33) that detects the contact of the conductor on the basis of the first quadrature phase component (Q1) when the first quadrature phase component (Q1) and the second quadrature phase component (Q2) are within the range of the first quadrature phase error ([Delta] QE1). When the first quadrature phase component (Q1) and the second quadrature phase component (Q2) are outside the range of the first quadrature phase error ([Delta] QE1), the contact of the conductor is detected on the basis of the alternative quadrature phase component (QA).

Description

Technical Field

[0001] The invention relates to a contact detection device. Background Art

[0002] For example, a contact detection device is known that detects whether a person touches a steering wheel by assembling an electrostatic capacitance sensor in the steering wheel of a car. In the contact detection device, the following impedance measurement is used: when measuring electrostatic capacitance, a voltage waveform of a certain period is applied to the sensor electrode, and the original waveform after the waveform is applied is compared with the measured waveform after passing through the sensor, thereby calculating the capacitance component.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-190990 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In conventional impedance measurement, the following technology is used: when a voltage is applied to an object, the phase of the current is delayed by the capacitance component of the sensor electrode, and a phase difference occurs between the measured voltage waveform and the applied voltage waveform. Therefore, when measuring impedance, there is a problem that when frequency noise near the frequency of the applied voltage is input to the sensor, the applied waveform is distorted, and accurate electrostatic capacitance measurement cannot be performed.

[0008] The present invention has been made in view of the above background, and provides a contact detection device that reduces the influence of noise.

[0009] Means used to solve problems

[0010] One embodiment of the present invention is a contact detection device comprising:

[0011] Electrostatic sensors, which have detection electrodes and detect contact with a conductor;

[0012] an AC power source for applying an AC voltage to the detection electrode;

[0013] a quadrature demodulator for extracting at least the quadrature phase component when the impedance of the electrostatic sensor is represented by an in-phase component and a quadrature phase component, using a signal output from the detection electrode when the AC voltage is applied to the detection electrode; and

[0014] a measuring device for detecting whether the conductor is in contact with the electrostatic sensor based on the quadrature phase component extracted by the quadrature demodulator,

[0015] The AC power source switches between a first AC voltage of a first frequency and a second AC voltage of a second frequency different from the first frequency and applies the voltages to the detection electrode.

[0016] The measuring device comprises:

[0017] a storage unit storing a substitute quadrature phase component corresponding to a state in which the conductor contacts the electrostatic sensor;

[0018] a quadrature phase component comparison section that compares a first quadrature phase component extracted by the quadrature demodulator when the first AC voltage is applied to the detection electrode and a second quadrature phase component extracted by the quadrature demodulator when the second AC voltage is applied to the detection electrode; and

[0019] A contact determination unit detects contact of the conductor with the electrostatic sensor based on the first quadrature phase component when the first quadrature phase component and the second quadrature phase component are within a range of a predetermined first quadrature phase error, and detects contact of the conductor with the electrostatic sensor based on the alternative quadrature phase component stored in the storage unit when the first quadrature phase component and the second quadrature phase component are outside the range of the first quadrature phase error.

[0020] Effects of the Invention

[0021] According to one embodiment of the present invention, even when noise of a frequency near the first frequency is mixed, the contact of the conductor to the detection electrode can be detected based on the second quadrature phase component of the second AC voltage. In addition, even when noise of a frequency near the second frequency is mixed, the contact of the conductor to the detection electrode can be detected based on the alternative quadrature phase component stored in the storage unit. Thus, the influence of noise can be reduced for the contact detection device.

[0022] In addition, the reference numerals in parentheses described in the claims indicate the corresponding relationship with the specific means described in the embodiments described later, and do not limit the technical scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a front view showing a steering wheel to which the contact detection device according to the first embodiment is applied.

[0024] Figure 2 Figure 1 Sectional view along line II-II.

[0025] Figure 3 This is a cross-sectional view showing the electrostatic sensor according to the first embodiment.

[0026] Figure 4 This is a block diagram showing the structure of the contact detection device according to the first embodiment.

[0027] Figure 5 This is a schematic diagram showing a state of output impedance in a state where there is no influence of noise and the conductors are not in contact, using a quadrature phase component and an in-phase phase component in the electrostatic sensor according to the first embodiment.

[0028] Figure 6 This is a schematic diagram showing the output impedance in a state where the conductors are in contact and the output impedance in a state where the conductors are not in contact, in the electrostatic sensor according to the first embodiment, using a quadrature phase component and an in-phase component.

[0029] Figure 7 This is a flowchart showing the main flow of the operation of the contact detection device according to the first embodiment.

[0030] Figure 8 This is a flowchart showing the noise determination process according to the first embodiment.

[0031] Fig. 9 This is a flowchart showing the quadrature phase component comparison process according to the first embodiment.

[0032] Fig.10 This is a flowchart showing the in-phase component comparison process according to the first embodiment.

[0033] Fig.11 This is a block diagram showing the structure of a contact detection device according to the second embodiment.

[0034] Fig.12 This is a flowchart showing the noise determination process according to the second embodiment.

[0035] Fig.13 This is a flowchart showing the quadrature phase component comparison process according to the second embodiment.

[0036] Fig.14 This is a flowchart showing the in-phase component comparison processing according to the second embodiment. DETAILED DESCRIPTION

[0037] (Implementation Method 1)

[0038] 1. Structure of steering wheel 1

[0039] Embodiment 1 in which the contact detection device 10 according to the present invention is applied to a steering wheel 1 of a vehicle (not shown) will be described. Figure 1-2 The structure of the steering wheel 1 is described. Figure 1As shown, the steering wheel 1 is formed of a circular ring portion 2, a core portion 3 formed smaller than the ring portion 2 and arranged radially inward of the ring portion 2, and a plurality of (three in this embodiment) connecting portions 4 connecting the core portion 3 and the ring portion 2. However, the number of the connecting portions 4 is not particularly limited, and may be one to two, or four or more.

[0040] In the following description, the right direction viewed from a driver (not shown) riding in a vehicle (not shown) is set as the direction indicated by arrow X, the top direction viewed from the driver is set as the direction indicated by arrow Z, and the direction close to the front of the driver is set as the direction indicated by arrow Y.

[0041] like Figure 2 As shown, the ring portion 2 includes a core 5, a resin inner layer material 6, an electrostatic sensor 7, and a skin material 8. The core 5 constitutes the central portion of the ring portion 2 and is formed into a shape corresponding to the shape of the ring portion 2. That is, the core 5 is formed into a circular ring shape and has a circular cross-section at right angles to the axis. Here, the cross-sectional shape of the core 5 at right angles to the axis is not limited to a circle, and can be set to any shape such as an elliptical shape, an egg shape, a U shape, a C shape, a polygonal shape, etc. The core 5 of this embodiment is formed of metals such as aluminum and magnesium and has conductivity. The material of the core 5 can be applied to materials other than metals.

[0042] The resin inner layer material 6 covers the outer surface of the core 5 over the entire circumference of the annular shape of the core 5 and over the entire circumference of the circular cross-sectional shape of the core 5. In this embodiment, the cross section of the resin inner layer material 6 at right angles to the axis is formed into a circle. Assuming that the core 5 has a U-shaped cross section at right angles to the axis, the resin inner layer material 6 is filled in addition to the radial outer side of the cross section of the core 5 at right angles to the axis, and is also filled in the U-shaped recess of the core 5. The resin inner layer material 6 is formed into the outer surface side of the core 5 by injection molding and is directly bonded to the outer surface of the core 5. The cross-sectional shape of the resin inner layer material 6 at right angles to the axis is not limited to a circle, and can be set to any shape such as an egg shape, an elliptical shape, a polygonal shape, etc. The resin inner layer material 6 uses, for example, a foamed polyurethane resin. In addition, the resin inner layer material 6 can also use a non-foamed resin.

[0043] An electrostatic sensor 7 is disposed on the outer surface of the resin inner layer material 6. The electrostatic sensor 7 is configured so that when a conductor (not shown) such as a finger or a hand contacts or approaches the electrostatic sensor 7, the electrostatic capacitance equivalent value of the electrostatic sensor 7 changes. The electrostatic sensor 7 involved in this embodiment is a steering wheel sensor applied to the steering wheel 1 of a vehicle. The electrostatic sensor 7 will be described in detail later.

[0044] The skin material 8 covers the entire circumference of the electrostatic sensor 7 in the outer surface of the electrostatic sensor 7 (the surface on the side opposite to the resin inner layer material 6 in the electrostatic sensor 7). That is, as described later, when the first electrode layer 22 is exposed on the first surface 24 side of the insulating sheet 21, the skin material 8 also functions as a covering material for the first electrode layer 22. The skin material 8 is formed by injection molding, and is wound around the outer surface side of the electrostatic sensor 7 and bonded to the outer surface of the electrostatic sensor 7. The skin material 8 is formed of, for example, a polyurethane resin. The outer surface of the skin material 8 constitutes an appearance surface. Therefore, the skin material 8 preferably uses a non-foamed polyurethane resin or a slightly foamed polyurethane resin.

[0045] Next, refer to Figure 3 The structure of the electrostatic sensor 7 will be described. The electrostatic sensor 7 includes a first electrode layer 22 and a second electrode layer 23. The first electrode layer 22 and the second electrode layer 23 are conductive and are formed in a layer shape. The first electrode layer 22 and the second electrode layer 23 are provided as an example of a detection electrode.

[0046] The first electrode layer 22 is stacked on the first surface 24 of the insulating sheet 21. The first electrode layer 22 is formed in a shape slightly smaller than the insulating sheet 21. Thus, the edge of the first surface 24 of the insulating sheet 21 is exposed from the edge of the first electrode layer 22.

[0047] The second electrode layer 23 is stacked on the second surface 25 of the insulating sheet 21. The second electrode layer 23 is formed in a shape slightly smaller than the insulating sheet 21. Thus, the edge of the second surface 25 of the insulating sheet 21 is exposed from the edge of the second electrode layer 23.

[0048] The first electrode layer 22 and the second electrode layer 23 may be of the same shape and size, or may be of similar shape with one being slightly larger than the other.

[0049] The insulating sheet 21 is formed, for example, to include an elastomer as a main component. Therefore, the insulating sheet 21 is soft. That is, the insulating sheet 21 has flexibility and is configured to be able to stretch in the plane direction. The insulating sheet 21 is formed, for example, to include a thermoplastic material, particularly a thermoplastic elastomer, as a main component. The insulating sheet 21 may be formed of a thermoplastic elastomer itself, or may be formed of a cross-linked elastomer as a main component by heating a thermoplastic elastomer as a material.

[0050] In addition, the insulating sheet 21 may also include rubber, resin, and other materials other than thermoplastic elastomers. For example, when the insulating sheet 21 includes rubber such as ethylene-propylene rubber (EPM, EPDM), the flexibility of the insulating sheet 21 is improved. From the viewpoint of improving the flexibility of the insulating sheet 21, the insulating sheet 21 may contain a flexibility-imparting component such as a plasticizer. Furthermore, the insulating sheet 21 may be configured to include a reaction-curable elastomer or a thermosetting elastomer as a main component.

[0051] Furthermore, the insulating sheet 21 is preferably made of a material having good thermal conductivity. Therefore, the insulating sheet 21 may be made of a thermoplastic elastomer having high thermal conductivity, or may contain a filler capable of improving thermal conductivity.

[0052] The first electrode layer 22 is arranged on the first surface 24 side of the insulating sheet 21, and the second electrode layer 23 is arranged on the second surface 25 side of the insulating sheet 21. The first electrode layer 22 and the second electrode layer 23 are conductive. Furthermore, the first electrode layer 22 and the second electrode layer 23 are soft. That is, the first electrode layer 22 and the second electrode layer 23 are flexible and are configured to be able to extend in the surface direction.

[0053] The first electrode layer 22 and the second electrode layer 23 may be formed of a conductive elastomer. When the first electrode layer 22 and the second electrode layer 23 are formed of a conductive elastomer, the first electrode layer 22 and the second electrode layer 23 are formed using the elastomer as the main material and containing a conductive filler. The main material of the first electrode layer 22 and the second electrode layer 23, i.e., the elastomer, may have the same main component as the insulating sheet 21, or may use a different material. The first electrode layer 22 and the second electrode layer 23, and the insulating sheet 21 are bonded by mutual fusion (thermal fusion).

[0054] The first electrode layer 22 and the second electrode layer 23 may be formed of conductive cloth. Conductive cloth is a fabric or nonwoven fabric formed of conductive fibers. Here, the conductive fibers are formed by covering the surface of flexible fibers with a conductive material. The conductive fibers are formed, for example, by electroplating copper, nickel, etc. on the surface of resin fibers such as polyethylene. In this case, the first electrode layer 22 and the second electrode layer 23 are bonded to the insulating sheet 21 by welding (thermal welding) the insulating sheet 21 itself.

[0055] The first electrode layer 22 and the second electrode layer 23 may be formed of metal foil. The metal foil may be a metal material capable of conducting electricity, such as copper foil, aluminum foil, etc. Further, as in the case of the conductive cloth, the first electrode layer 22 and the second electrode layer 23 are bonded to the sensor sheet by welding (thermal welding) of the insulating sheet 21 itself.

[0056] 3. Overall structure of the contact detection device 10

[0057] like Figure 4 As shown, the contact detection device 10 includes the electrostatic sensor 7, the AC power supply 11, the quadrature demodulator 12, and the measuring device 30. The AC voltage from the AC power supply 11 is applied to the first electrode layer 22 and the second electrode layer 23 of the electrostatic sensor 7.

[0058] (1) AC power supply 11

[0059] The AC power source 11 switches a first AC voltage of a first frequency, a second AC voltage of a second frequency, and a third AC voltage of a third frequency at a predetermined period and applies them to the first electrode layer 22 and the second electrode layer 23. The first frequency, the second frequency, and the third frequency are different from each other. However, the frequencies of the AC voltages applied to the first electrode layer 22 and the second electrode layer 23 are not limited to three, and may be two or more than four.

[0060] In this embodiment, the first frequency is greater than the second frequency, and the second frequency is greater than the third frequency. In this embodiment, the first frequency is 100 to 150 kHz, the second frequency is 50 to 100 kHz, and the third frequency is 5 to 50 kHz. However, the frequency bands of the first frequency, the second frequency, and the third frequency are not limited to the above numerical ranges.

[0061] The first frequency is 100 to 150 kHz, and thus, for example, the influence of noise based on the switching frequency (100 kHz) of a DC-DC converter of a smart key for a vehicle, noise based on amateur radio (135.7 kHz, 137.8 kHz), etc. can be reduced.

[0062] The second frequency is 50 to 100 kHz, and thus, for example, the influence of noise and the like based on wireless power transmission (79 to 90 kHz) can be reduced.

[0063] The third frequency is 5 to 50 kHz, thereby making it possible to reduce the influence of noise based on, for example, standard radio waves (40 kHz, 60 kHz) received by the radio-controlled timepiece.

[0064] (2) Quadrature demodulator 12

[0065] Reference Figure 5 as well as Figure 6 , the quadrature demodulator 12 is described. The quadrature demodulator 12 uses the signal output from the first electrode layer 22 when the AC voltage is applied to the second electrode layer 23, and extracts the quadrature phase component and the in-phase phase component when the impedance of the electrostatic sensor 7 is represented by the in-phase component and the quadrature phase component. However, the quadrature demodulator 12 may be configured to extract only the quadrature phase component.

[0066] Reference Figure 5 (a)~ Figure 5(c) in FIG. 1 illustrates the operation of the orthogonal demodulator 12. Figure 5 (a) in FIG. 1 is a graph showing the output impedance of the signal output from the first electrode layer 22 as the first quadrature phase component Q1 (an example of the first quadrature phase component) and the first in-phase phase component I1 (an example of the first in-phase phase component) when the first AC voltage is applied to the second electrode layer 23 in a state where the electrostatic sensor 7 is not affected by noise and the conductor is not in contact with the first electrode layer 22. As described above, the quadrature demodulator 12 extracts the quadrature phase component and the quadrature phase component for the impedance of the electrostatic sensor 7 using the signal output from the first electrode layer 22.

[0067] Figure 5 (b) in the figure represents the following graph: when the electrostatic sensor 7 is not affected by noise and the conductor is not in contact with the first electrode layer 22, when the second AC voltage is applied to the second electrode layer 23, the output impedance involved in the signal output from the first electrode layer 22 is shown by the second orthogonal phase component Q2 (an example of the second orthogonal phase component) and the second in-phase component I2 (an example of the second in-phase phase component).

[0068] The first frequency of the first AC voltage is different from the second frequency of the second AC voltage, so the first quadrature phase component Q1 is different from the second quadrature phase component Q2, and the first in-phase phase component I1 is different from the second in-phase phase component I2. Therefore, by modifying the second quadrature phase component Q2 and the second in-phase phase component I2, they are converted into the modified second quadrature phase component QC2 and the modified second in-phase phase component IC2, respectively. As a result, the first quadrature phase component Q1 and the modified second quadrature phase component QC2 can be compared, and the first in-phase phase component I1 and the modified second in-phase phase component IC2 can be compared. In a state where the electrostatic sensor 7 does not receive noise, the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1 described later, and the first in-phase phase component I1 and the modified second in-phase phase component IC2 are within the range of the first in-phase phase error ΔIE1 described later.

[0069] Figure 5 (c) in the figure represents the following graph: when the third AC voltage is applied to the second electrode layer 23 in a state where the electrostatic sensor 7 is not affected by noise and the conductor is not in contact with the first electrode layer 22, the output impedance involved in the signal output from the first electrode layer 22 is shown by the third orthogonal phase component Q3 (an example of the third orthogonal phase component) and the third in-phase component I3 (an example of the third in-phase phase component).

[0070] The first frequency of the first AC voltage is different from the second frequency of the third AC voltage, so the first quadrature phase component Q1 is different from the third quadrature phase component Q3, and the first in-phase phase component I1 is different from the third in-phase phase component I3. Therefore, by modifying the third quadrature phase component Q3 and the third in-phase phase component I3, they are converted into the modified third quadrature phase component QC3 and the modified third in-phase phase component IC3, respectively. As a result, the first quadrature phase component Q1 and the modified third quadrature phase component QC3 can be compared, and the first in-phase phase component I1 and the modified third in-phase phase component IC3 can be compared. In the state where the electrostatic sensor 7 does not receive noise, the first quadrature phase component Q1 and the modified third quadrature phase component QC3 are within the range of the second quadrature phase error ΔQE2 described later, and the first in-phase phase component I1 and the modified third in-phase phase component IC3 are within the range of the second in-phase phase error ΔIE2 described later.

[0071] In addition, the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 can be compared, and the modified second in-phase phase component IC2 and the modified third in-phase phase component IC3 can be compared. In a state where the electrostatic sensor 7 does not receive noise, the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 are within the range of the third quadrature phase error ΔQE3 described later, and the modified second in-phase phase component IC2 and the modified third in-phase phase component IC3 are within the range of the third in-phase phase error ΔIE3 described later.

[0072] However, the modification may be, for example, multiplying the second quadrature phase component Q2, the second in-phase phase component I2, the third quadrature phase component Q3, and the third in-phase phase component I3 by a modification coefficient, or multiplying the second quadrature phase component Q2, the second in-phase phase component I2, the third quadrature phase component Q3, and the third in-phase phase component I3 by a modification function. The modification coefficient or the modification function can be obtained through experiments.

[0073] Figure 6 : represents the output impedance in a state where the conductor is in contact with the first electrode layer 22, and the output impedance in a state where the conductor is not in contact with the first electrode layer 22, when the first AC voltage is applied to the electrostatic sensor 7. However, the state where the conductor is in contact with the first electrode layer 22 includes a state where the conductor is in contact with the first electrode layer 22 directly, and includes a state where the conductor is in contact with the first electrode layer 22 indirectly via the surface material 8.

[0074] When the first electrode layer 22 contacts the conductor, both the capacitance component and the resistance component of the electrostatic sensor 7 increase, so the output impedance when the conductor contacts changes in the direction in which both the quadrature phase component and the in-phase phase component increase compared to the output impedance when the conductor does not contact. That is, the first quadrature phase component Q1 (contact) when the conductor contacts is greater than the first quadrature phase component Q1 (not contact) when the conductor does not contact. In addition, the first in-phase phase component I1 (contact) when the conductor contacts is greater than the first in-phase phase component I1 (not contact) when the conductor does not contact.

[0075] In addition, when the second AC voltage is applied to the electrostatic sensor 7 and when the third AC voltage is applied to the electrostatic sensor 7, the same tendency as when the first AC voltage is applied is shown, so repeated description is omitted.

[0076] (3) Measuring device 30

[0077] Back to Figure 4 The measuring device 30 includes a quadrature phase component comparison unit 31 , an in-phase phase component comparison unit 32 , a contact determination unit 33 , a storage unit 34 , a quadrature phase component update unit 35 , and an in-phase phase component update unit 36 ​​.

[0078] (4) Storage unit 34

[0079] like Figure 4 As shown, the storage unit 34 stores the substitute quadrature phase component QA and the substitute in-phase phase component IA corresponding to the state where the conductor contacts the electrostatic sensor 7. The substitute quadrature phase component QA is an initial value stored in the storage unit 34 in advance, and is a value that is not updated in the contact detection by the measuring device 30. In addition, the substitute in-phase phase component IA is an initial value stored in the storage unit 34 in advance, and is a value that is not updated in the contact detection by the measuring device 30. However, when the contact detection by the measuring device 30 is not performed, the substitute quadrature phase component QA and the substitute in-phase phase component IA can be updated.

[0080] The storage unit 34 also stores a quadrature phase component reference value QB and an in-phase phase component reference value IB. The quadrature phase component reference value QB is the quadrature phase component extracted from the signal output from the first electrode layer 22 when the first AC voltage is applied to the second electrode layer 23, in a state where the electrostatic sensor 7 is not affected by noise and the conductor is not in contact with the first electrode layer 22. The in-phase phase component reference value IB is the in-phase phase component extracted from the signal output from the first electrode layer 22 when the first AC voltage is applied to the second electrode layer 23, in a state where the electrostatic sensor 7 is not affected by noise and the conductor is not in contact with the first electrode layer 22.

[0081] The storage unit 34 further stores a first quadrature phase error ΔQE1 , a first in-phase phase error ΔIE1 , a second quadrature phase error ΔQE2 , a second in-phase phase error ΔIE2 , a third quadrature phase error ΔQE3 , and a third in-phase phase error ΔIE3 .

[0082] The first quadrature phase error ΔQE1 is used to compare the first quadrature phase component Q1 with the modified second quadrature phase component QC2. The first in-phase phase error ΔIE1 is used to compare the first in-phase phase component I1 with the modified second in-phase phase component IC2.

[0083] The second quadrature phase error ΔQE2 is used to compare the first quadrature phase component Q1 with the modified third quadrature phase component QC3. The second in-phase phase error ΔIE2 is used to compare the first in-phase phase component I1 with the modified third in-phase phase component IC3.

[0084] The third quadrature phase error ΔQE3 is used to compare the modified second quadrature phase component QC2 with the modified third quadrature phase component QC3. The third in-phase phase error ΔIE3 is used to compare the modified second in-phase phase component IC2 with the modified third in-phase phase component IC3.

[0085] (5) Quadrature Phase Component Comparison Unit 31

[0086] When AC voltages of different frequencies are applied to the second electrode layer 23 , the quadrature phase component comparison unit 31 compares the quadrature phase components extracted by the quadrature demodulator 12 based on signals of different frequencies output from the second electrode layer 23 .

[0087] like Figure 4 as well as Figure 5 As shown, in this embodiment, the orthogonal phase component comparison unit 31 compares the first orthogonal phase component Q1 with the second orthogonal phase component Q2. When the first AC voltage is applied to the second electrode layer 23, the first orthogonal phase component Q1 is extracted from the signal output from the first electrode layer 22 by the orthogonal demodulator 12. When the second AC voltage is applied to the second electrode layer 23, the second orthogonal phase component Q2 is extracted from the signal output from the first electrode layer 22 by the orthogonal demodulator 12. However, instead of the second orthogonal phase component Q2, the modified second orthogonal phase component QC2 may be compared with the first orthogonal phase component Q1.

[0088] In addition, the orthogonal phase component comparison unit 31 compares the first orthogonal phase component Q1 with the third orthogonal phase component Q3. When the third AC voltage is applied to the second electrode layer 23, the third orthogonal phase component Q3 is extracted from the signal output from the first electrode layer 22 by the orthogonal demodulator 12. However, the orthogonal phase component comparison unit 31 may compare the modified third orthogonal phase component QC3 with the first orthogonal phase component Q1 instead of the third orthogonal phase component Q3.

[0089] In addition, the orthogonal phase component comparison unit 31 compares the second orthogonal phase component Q2 with the third orthogonal phase component Q3. However, the second orthogonal phase component Q2 can be replaced by the modified second orthogonal phase component QC2, and the third orthogonal phase component Q3 can be replaced by the modified third orthogonal phase component QC3. Therefore, the orthogonal phase component comparison unit 31 can compare the modified second orthogonal phase component QC2 with the third orthogonal phase component Q3, and can also compare the second orthogonal phase component Q2 with the modified third orthogonal phase component QC3, and can also compare the modified second orthogonal phase component QC2 with the modified third orthogonal phase component QC3.

[0090] (6) In-phase component comparison unit 32

[0091] The in-phase component comparison unit 32 compares the in-phase components extracted by the orthogonal demodulator 12 based on the signals of different frequencies output from the second electrode layer 23 when AC voltages of different frequencies are applied to the second electrode layer 23 .

[0092] like Figure 4 as well as Figure 5 As shown, in this embodiment, the in-phase component comparison unit 32 compares the first in-phase component I1 with the second in-phase component I2. When the first AC voltage is applied to the second electrode layer 23, the first in-phase component I1 is extracted from the signal output from the first electrode layer 22 through the orthogonal demodulator 12. When the second AC voltage is applied to the second electrode layer 23, the second in-phase component I2 is extracted from the signal output from the first electrode layer 22 through the orthogonal demodulator 12. However, the in-phase component comparison unit 32 may compare the modified second in-phase component IC2 with the first in-phase component I1 instead of the second in-phase component I2.

[0093] In addition, the in-phase component comparison unit 32 compares the first in-phase component I1 with the third in-phase component I3. When the third AC voltage is applied to the second electrode layer 23, the third in-phase component I3 is extracted from the signal output from the first electrode layer 22 by the orthogonal demodulator 12. However, the in-phase component comparison unit 32 may compare the modified third in-phase component IC3 with the first in-phase component I1 instead of the third in-phase component I3.

[0094] In addition, the in-phase phase component comparison unit 32 compares the second in-phase phase component I2 with the third in-phase phase component I3. However, the second in-phase phase component I2 can be replaced by the modified second in-phase phase component IC2, and the third in-phase phase component I3 can be replaced by the modified third in-phase phase component IC3. Therefore, the in-phase phase component comparison unit 32 can compare the modified second in-phase phase component IC2 with the third in-phase phase component I3, and can also compare the second in-phase phase component I2 with the modified third in-phase phase component IC3, and can also compare the modified second in-phase phase component IC2 with the modified third in-phase phase component IC3.

[0095] (7) Contact determination unit 33

[0096] like Figure 4 As shown, the contact determination unit 33 selects the orthogonal phase component that serves as a reference for detecting the contact of the conductor to the electrostatic sensor 7 based on the comparison result by the orthogonal phase component comparison unit 31. In addition, the contact determination unit 33 selects the in-phase phase component that serves as a reference for detecting the contact of the conductor to the electrostatic sensor 7 based on the comparison result by the in-phase phase component comparison unit 32. The contact determination unit 33 detects the contact of the conductor to the electrostatic sensor 7 based on the selected orthogonal phase component and the in-phase phase component.

[0097] Table 1 summarizes the combinations of selected quadrature-phase components and selected in-phase components.

[0098] [Table 1]

[0099] (Table 1)

[0100]

[0101] (8) Quadrature Phase Component Updater 35

[0102] like Figure 4As shown, when the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1, the quadrature phase component update unit 35 updates the first quadrature phase component Q1 used for the contact determination unit 33 as the substitute quadrature phase component QA stored in the storage unit 34. In addition, when the first quadrature phase component Q1 and the modified third quadrature phase component QC3 are within the range of the second quadrature phase error ΔQE2, the quadrature phase component update unit 35 updates the first quadrature phase component Q1 used for the contact determination unit 33 as the substitute quadrature phase component QA stored in the storage unit 34. In addition, when the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 are within the range of the third quadrature phase error ΔQE3, the quadrature phase component update unit 35 updates the modified second quadrature phase component QC2 used for the contact determination unit 33 as the substitute quadrature phase component QA stored in the storage unit 34.

[0103] (9) In-phase component update unit 36

[0104] like Figure 4 As shown, when the first in-phase phase component I1 and the modified second in-phase phase component IC2 are within the range of the first in-phase phase error ΔIE1, the in-phase phase component update unit 36 ​​updates the first in-phase phase component I1 for the contact determination unit 33 as the substitute in-phase phase component IA stored in the storage unit 34. In addition, when the first in-phase phase component I1 and the modified third in-phase phase component IC3 are within the range of the second in-phase phase error ΔIE2, the in-phase phase component update unit 36 ​​updates the first in-phase phase component I1 for the contact determination unit 33 as the substitute in-phase phase component IA stored in the storage unit 34. In addition, when the modified second in-phase phase component IC2 and the modified third in-phase phase component IC3 are within the range of the third in-phase phase error ΔIE3, the in-phase phase component update unit 36 ​​updates the modified second in-phase phase component IC2 for the contact determination unit 33 as the substitute in-phase phase component IA stored in the storage unit 34.

[0105] 4. Operation of the contact detection device 10

[0106] Figure 7 The following is a main routine related to the operation of the contact sensing device 10. When the contact sensing device 10 is operated, a measurement process is executed (S1).

[0107] (1) Measurement processing (S1)

[0108] In the measurement process (S1), the first quadrature phase component Q1 and the first in-phase phase component I1 (see Figure 5In addition, in the measurement process (S1), the second quadrature phase component Q2 and the second in-phase phase component I2 are measured and modified into the modified second quadrature phase component QC2 and the modified second in-phase phase component IC2, respectively (refer to Figure 5 In addition, in the measurement process (S1), the third quadrature phase component Q3 and the third in-phase phase component I3 are measured and modified into the modified third quadrature phase component QC3 and the modified third in-phase phase component IC3 respectively (refer to Figure 5 (c) in the figure.

[0109] (2) Noise determination processing

[0110] like Figure 7 As shown, when the measurement process (S1) is executed, the noise determination process (S2) is executed. In the noise determination process (S2), it is determined whether the electrostatic sensor 7 is affected by noise. Figure 8 A flowchart showing the noise determination process. When the noise determination process (S2) is executed, the quadrature phase component comparison process (S10) and the in-phase phase component comparison process (S20) are executed at the same timing, and the noise determination process (S2) ends.

[0111] (A) Quadrature Phase Component Comparison Processing

[0112] Fig. 9 Flowchart showing the orthogonal phase component comparison process (S10). When the orthogonal phase component comparison process (S10) is executed, the orthogonal phase component comparison unit 31 compares the first orthogonal phase component Q1 with the modified second orthogonal phase component QC2 (refer to Figure 5 ). When the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1 stored in the storage unit 34 (S11: Yes), the quadrature phase component comparison unit 31 selects the first quadrature phase component Q1 as a reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S12). In terms of the nature of impedance, the higher the frequency, the higher the accuracy of the contact detection of the conductor. Therefore, by using the first quadrature phase component Q1 to which the first AC voltage having a first frequency greater than the second frequency is applied, the accuracy of detecting whether the conductor is in contact with the electrostatic sensor 7 can be improved. With the above, the quadrature phase component comparison process (S10) ends.

[0113] When the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are not within the range of the first quadrature phase error ΔQE1 ( S11 : NO), the electrostatic sensor 7 determines that it is affected by noise having a frequency near the first frequency or noise having a frequency near the second frequency.

[0114] Next, the quadrature phase component comparison unit 31 compares the first quadrature phase component Q1 with the modified third quadrature phase component QC3 (see Figure 5 ). When the first quadrature phase component Q1 and the modified third quadrature phase component QC3 are within the range of the second quadrature phase error ΔQE2 stored in the storage unit 34 (S13: Yes), the quadrature phase component comparison unit 31 selects the first quadrature phase component Q1 based on the first frequency greater than the third frequency as a reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S14). With the above, the quadrature phase component comparison process (S10) ends.

[0115] When the first quadrature phase component Q1 and the modified third quadrature phase component QC3 are not within the range of the second quadrature phase error ΔQE2 ( S13 : NO), the electrostatic sensor 7 determines that it is affected by noise having a frequency near the first frequency or noise having a frequency near the third frequency.

[0116] Next, the quadrature phase component comparison unit 31 compares the modified second quadrature phase component QC2 with the modified third quadrature phase component QC3 (see Figure 5 ). When the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 are within the range of the third quadrature phase error ΔQE3 stored in the storage unit 34 (S15: Yes), the quadrature phase component comparison unit 31 selects the modified second quadrature phase component QC2 based on the second frequency greater than the third frequency as the reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S16). As described above, the quadrature phase component comparison process (S10) ends.

[0117] When the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 are not within the range of the third quadrature phase error ΔQE3 ( S15 : No), the electrostatic sensor 7 determines that it is affected by noise having a frequency near the second frequency or noise having a frequency near the third frequency.

[0118] Next, the quadrature phase component comparison unit 31 selects the alternative quadrature phase component QA stored in the storage unit 34 as a reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S17). The quadrature phase component comparison process (S10) ends as described above.

[0119] (B) In-phase phase component comparison processing

[0120] Fig.10 The flowchart of the in-phase component comparison process (S20) is shown. The in-phase component comparison process is similar to the above-mentioned "(A) quadrature phase component comparison process" and Fig. 9For comparison, except that "orthogonal" is replaced by "in-phase" and the reference numeral "Q" is replaced by the reference numeral "I", everything else is the same, so repeated description is omitted and only the conclusion is recorded below.

[0121] In the case where the first in-phase component I1 and the modified second in-phase component IC2 are within the range of the first in-phase phase error ΔIE1 ( S21 : Yes), the first in-phase component I1 is selected ( S22 ).

[0122] In the case where the first in-phase component I1 and the modified third in-phase component IC3 are within the range of the second in-phase phase error ΔIE2 ( S23 : Yes), the first in-phase component I1 is selected ( S24 ).

[0123] When the modified second in-phase component IC2 and the modified third in-phase component IC3 are within the range of the third in-phase phase error ΔIE3 ( S25 : Yes), the modified second in-phase component IC2 is selected ( S26 ).

[0124] When the first in-phase phase component I1 and the modified second in-phase phase component IC2 are not within the range of the first in-phase phase error ΔIE1 (S21: No), the first in-phase phase component I1 and the modified third in-phase phase component IC3 are not within the range of the second in-phase phase error ΔIE2 (S23: No), and the modified second in-phase phase component IC2 and the modified third in-phase phase component IC3 are not within the range of the third in-phase phase error ΔIE3 (S25: No), select the replacement in-phase phase component IA (S27).

[0125] (3) Contact detection processing

[0126] like Figure 7 As shown, if the noise determination process (S2) is completed, the contact detection process (S3) is executed. In the contact detection process (S3), the contact determination unit 33 detects the contact of the conductor to the electrostatic sensor 7 based on the orthogonal phase components Q1, Q2, Q3 or the modified orthogonal phase components QC2, QC3 selected in the noise determination process, and the in-phase phase components I1, I2, I3 or the modified in-phase phase components IC2, IC3. In this embodiment, the contact determination unit 33 detects the contact of the conductor to the electrostatic sensor 7 based on the combination shown in Table 1. However, it can also be a combination different from Table 1. The operation of the contact determination unit 33 is described below.

[0127] Contact determination unit 33 calculates a difference between quadrature phase components Q1 , Q2 , Q3 or corrected quadrature phase components QC2 , QC3 selected in noise determination processing ( S2 ) and quadrature phase component reference value QB stored in storage unit 34 .

[0128] When the difference between the selected quadrature phase components Q1, Q2, Q3 or the modified quadrature phase components QC2, QC3 and the quadrature phase component reference value QB is greater than a predetermined threshold, the contact determination unit 33 determines that the conductor is in contact with the first electrode layer 22. On the other hand, when the difference between the selected quadrature phase components Q1, Q2, Q3 or the modified quadrature phase components QC2, QC3 and the quadrature phase component reference value QB is less than a predetermined threshold, the contact determination unit 33 determines that the conductor is in contact with the first electrode layer 22. The above threshold may be stored in the storage unit 34.

[0129] The contact determination unit 33 calculates a difference between the in-phase components I1 , I2 , I3 or the corrected in-phase components IC2 , IC3 selected in the noise determination process ( S2 ) and the in-phase component reference value IB stored in the storage unit 34 .

[0130] The contact determination unit 33 determines whether the conductor contacts the first electrode layer 22 of the electrostatic sensor 7 in the same manner as described above, based on the selected in-phase components I1, I2, and I3 or the modified in-phase components IC2 and IC3, and the difference between the in-phase component reference value IB. Except that "orthogonal" is replaced by "in-phase" and the reference symbol "Q" is replaced by the reference symbol "I", the rest is the same as described above, so repeated descriptions are omitted. With the above, the contact detection process (S3) ends.

[0131] However, in this method, when it is determined that the conductor is in contact with the first electrode layer 22 based on the orthogonal phase component selected in the noise determination process (S2), and when it is determined that the conductor is in contact with the first electrode layer 22 based on the in-phase phase component selected in the noise determination process (S2), it can be determined that the conductor is in contact with the first electrode layer 22. Thus, the accuracy of detecting the contact of the conductor with the electrostatic sensor 7 can be improved.

[0132] Alternatively, it may be configured to determine that the conductor is in contact with the first electrode layer 22 based only on the orthogonal phase component selected in the noise determination process (S2). This simplifies the processing steps of the contact detection process (S3).

[0133] In addition, based on both the quadrature phase component selected in the noise determination process (S2) and the in-phase component selected in the noise determination process (S2), it is possible to accurately determine whether the conductor in contact with the first electrode layer 22 is a human body. For example, when the signal output from the first electrode layer 22 is represented as the quadrature phase component and the in-phase phase component, when the vector representing the signal is in a specific area, it is determined that the human body such as a hand or a finger is in contact with the first electrode layer 22, and when the above vector is in another area, it can be determined that the metal is in contact with the first electrode layer 22. In this way, the contact of the conductor with the first electrode layer 22 can be accurately detected.

[0134] (4) Update processing

[0135] like Figure 7 As shown, when the contact detection process (S3) is completed, the update process (S4) is executed.

[0136] In the quadrature phase component comparison process ( Fig. 9 In S10), when the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1 ( Fig. 9 ( S11 : Yes), the quadrature phase component updating unit 35 updates the first quadrature phase component Q1 used for the contact determination unit 33 as the alternative quadrature phase component QA stored in the storage unit 34 .

[0137] In addition, in the quadrature phase component comparison process ( Fig. 9 In S10), when the first quadrature phase component Q1 and the modified third quadrature phase component QC3 are within the range of the second quadrature phase error ΔQE2 ( Fig. 9 (S13: Yes), the quadrature phase component updating unit 35 updates the first quadrature phase component Q1 used for the contact determination unit 33 as the alternative quadrature phase component QA stored in the storage unit 34.

[0138] In addition, in the quadrature phase component comparison process ( Fig. 9 In S10), when the modified second quadrature phase component QC2 and the modified third quadrature phase component QC3 are within the range of the third quadrature phase error ΔQE3 ( Fig. 9 (S15: Yes), the quadrature phase component updating unit 35 updates the modified second quadrature phase component QC2 used for the contact determination unit 33 as the alternative quadrature phase component QA stored in the storage unit 34.

[0139] In addition, in the in-phase phase component comparison process ( Fig.10In S20), when the first in-phase component I1 and the modified second in-phase component IC2 are within the range of the first in-phase phase error ΔIE1 ( Fig.10 (S21: Yes), the in-phase component update unit 36 ​​updates the first in-phase component I1 used for the contact determination unit 33 as the alternative in-phase component IA stored in the storage unit 34.

[0140] In addition, in the in-phase phase component comparison process ( Fig.10 In S20), when the first in-phase component I1 and the modified third in-phase component IC3 are within the range of the second in-phase phase error ΔIE2 ( Fig.10 (S23: Yes), the in-phase component update unit 36 ​​updates the first in-phase component I1 used for the contact determination unit 33 as the alternative in-phase component IA stored in the storage unit 34.

[0141] In addition, in the in-phase phase component comparison process ( Fig.10 In S20), when the modified second in-phase component IC2 and the modified third in-phase component IC3 are within the range of the third in-phase phase error ΔIE3 ( Fig.10 (S25: Yes), the in-phase component update unit 36 ​​updates the modified second in-phase component IC2 used for the contact determination unit 33 as the alternative in-phase component IA stored in the storage unit 34. The update process (S4) is completed as described above.

[0142] (5) End selection

[0143] Next, if Figure 7 As shown, when there is no instruction to terminate (S5: No), the processes of S1 to S4 are repeated. On the other hand, when there is an instruction to terminate (S5: Yes), the contact detection device 10 terminates the operation.

[0144] 5. Effects of this method

[0145] Next, the effects of this method are described. According to this method, even when noise of a frequency near the first frequency is mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the modified second quadrature phase component QC2 involved in the second AC voltage. In addition, even when noise of a frequency near the second frequency is mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the first quadrature phase component Q1 involved in the first AC voltage. In addition, even when noise of a frequency near the first frequency and the second frequency is mixed, or when noise of a frequency close to the first frequency, the second frequency, and the third frequency is mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the alternative quadrature phase component QA stored in the storage unit 34. As a result, the influence of noise can be reduced on the contact detection device 10.

[0146] According to this embodiment, in order to detect contact of a conductor with the first electrode layer 22 of the electrostatic sensor 7 , the in-phase component is used in addition to the above-mentioned quadrature phase component, thereby improving the accuracy of the contact detection device 10 .

[0147] According to this method, in the case where noise of frequencies near the first frequency and the second frequency is mixed, or in the case where noise of frequencies close to the first frequency, the second frequency and the third frequency is mixed, the contact of the conductor with the first electrode layer 22 of the electrostatic sensor 7 can be detected based on the alternative orthogonal phase component QA stored in the storage unit 34 and used in the previous judgment, and the alternative in-phase component IA stored in the storage unit 34 and used in the previous judgment.

[0148] In addition, according to this embodiment, the first frequency is greater than the second frequency, and the second frequency is greater than the third frequency. In terms of impedance properties, by applying an AC voltage with a large frequency, the accuracy of the contact detection device 10 can be improved. According to this embodiment, in the case where noise with a frequency close to the first frequency is not mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the first AC voltage of the first frequency, and in the case where noise with a frequency close to the second frequency is not mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the second AC voltage of the second frequency, so that the accuracy of the contact detection device 10 can be improved as much as possible.

[0149] In addition, by storing a replacement orthogonal phase component QA that is used in the previous judgment and a replacement orthogonal phase component QA that is stored in the storage unit 34, and a replacement in-phase phase component IA that is used in the previous judgment and a replacement in-phase phase component IA that is stored in the storage unit 34, it is possible to correspond to the time-dependent changes of the electrostatic sensor 7, thereby improving the accuracy of the contact detection device 10.

[0150] (Implementation Method 2)

[0151] Next, refer to Fig.11 , the structure of the contact detection device 60 of the second embodiment is described. The AC power supply 11 of this embodiment switches the first AC voltage of the first frequency and the second AC voltage of the second frequency at a predetermined period and applies them to the first electrode layer 22 and the second electrode layer 23. The first frequency and the second frequency are different from each other. In this embodiment, the first frequency is greater than the second frequency.

[0152] The quadrature demodulator 12 of this embodiment extracts the first quadrature phase component Q1 and the first in-phase phase component I1 from the signal output from the first electrode layer 22 when the first AC voltage is applied to the second electrode layer 23 .

[0153] In addition, the orthogonal demodulator 12 of this embodiment extracts the second orthogonal phase component Q2 from the signal output from the first electrode layer 22 when the second AC voltage is applied to the second electrode layer 23 to generate a modified second orthogonal phase component QC2, and extracts the second in-phase component I2 to generate a modified second in-phase component IC2.

[0154] like Fig.11 As shown, the storage unit 64 of this embodiment stores the alternative quadrature phase component QA, the alternative in-phase phase component IA, the first quadrature phase error ΔQE1, and the first in-phase phase error ΔIE1.

[0155] The quadrature phase component comparison unit 31 of this embodiment compares the first quadrature phase component Q1 extracted by the quadrature demodulator 12 and the modified second quadrature phase component QC2 generated by the quadrature demodulator 12. However, the quadrature phase component comparison unit 31 may compare the second quadrature phase component Q2 with the first quadrature phase component Q1 instead of the modified second quadrature phase component QC2.

[0156] The in-phase component comparison unit 32 of this embodiment compares the first in-phase component I1 extracted by the quadrature demodulator 12 and the modified second in-phase component IC2 generated by the quadrature demodulator 12. However, the in-phase component comparison unit 32 compares the second in-phase component I2 with the first in-phase component I1 instead of the modified second in-phase component IC2.

[0157] The contact determination unit 33 of this embodiment selects the orthogonal phase component that serves as a reference for detecting the contact of the conductor to the electrostatic sensor 7 based on the comparison result in the orthogonal phase component comparison unit 31. In addition, the contact determination unit 33 selects the in-phase phase component that serves as a reference for detecting the contact of the conductor to the electrostatic sensor 7 based on the comparison result in the in-phase phase component comparison unit 32. The contact determination unit 33 detects the contact of the conductor to the electrostatic sensor 7 based on the selected orthogonal phase component and the in-phase phase component.

[0158] Table 2 summarizes the combinations of selected quadrature-phase components and selected in-phase phase components.

[0159] [Table 2]

[0160] (Table 2)

[0161]

[0162] When the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1, the quadrature phase component updater 35 of this embodiment updates the first quadrature phase component Q1 used for the contact determination unit 33 as the alternative quadrature phase component QA stored in the storage unit 64.

[0163] When the first in-phase component I1 and the modified second in-phase component IC2 are within the range of the first in-phase phase error ΔIE1, the in-phase component update unit 36 ​​of this method updates the first in-phase component I1 used for the contact determination unit 33 as the alternative in-phase component IA stored in the storage unit 64.

[0164] The configuration other than the above is substantially the same as that of the first embodiment, and therefore repeated descriptions are omitted.

[0165] Next, the operation of the contact detection device 60 of this embodiment will be described. The operation of the contact detection device 60 of this embodiment will be described with respect to the differences from the contact detection device 60 of Embodiment 1, and duplicate descriptions of the same operations will be omitted.

[0166] When the contact detection device 60 of this embodiment operates, the measurement process is performed ( Figure 7 In the measurement process (S1) of this method, the first quadrature phase component Q1 and the first in-phase phase component I1 are measured. In addition, in the measurement process (S1) of this method, the second quadrature phase component Q2 and the second in-phase phase component I2 are measured and modified to the modified second quadrature phase component QC2 and the modified second in-phase phase component IC2, respectively.

[0167] Next, noise determination processing is performed ( Figure 7 S2). Fig.12 As shown, in this method, when the noise determination process (S2) is executed, the quadrature phase component comparison process ( Fig.12 S30) and in-phase phase component comparison processing ( Fig.12 S40) is executed at the same timing, and the noise determination process (S2) ends.

[0168] Fig.13 The flowchart of the quadrature phase component comparison process (S30) of the present embodiment is shown. When the quadrature phase component comparison process (S30) is executed, the quadrature phase component comparison unit 31 compares the first quadrature phase component Q1 with the modified second quadrature phase component QC2. When the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1 stored in the storage unit 64 (S31: Yes), the quadrature phase component comparison unit 31 selects the first quadrature phase component Q1 as a reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S32).

[0169] When the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are not within the range of the first quadrature phase error ΔQE1 (S31: No), the quadrature phase component comparison unit 31 selects the alternative quadrature phase component QA stored in the storage unit 64 as a reference value for detecting the contact of the conductor with the electrostatic sensor 7 (S33). The quadrature phase component comparison process (S30) ends as described above.

[0170] Fig.14 The flowchart of the in-phase component comparison process (S40) is shown. The in-phase component comparison process is compared with the quadrature phase component comparison process described above (see Fig.13 ), except that “orthogonal” is replaced by “in-phase” and the reference numeral “Q” is replaced by the reference numeral “I”, the other parts are the same, so repeated description is omitted.

[0171] like Figure 7 As shown, when the noise determination process (S2) is completed, the contact detection process (S3) is executed. In the contact detection process (S3), the contact determination unit 33 detects the contact of the conductor with the electrostatic sensor 7 based on the orthogonal phase component and the in-phase component selected in the noise determination process.

[0172] The contact determination unit 33 involved in this embodiment detects the contact of the conductor to the electrostatic sensor 7 based on the orthogonal phase components Q1, Q2 or the modified orthogonal phase component QC2 selected in the noise determination process (S2). In addition, the contact determination unit 33 detects the contact of the conductor to the electrostatic sensor 7 based on the in-phase components I1, I2 or the modified in-phase components IC2 selected in the noise determination process. The process performed by the contact determination unit 33 is almost the same as that of the first embodiment, so repeated descriptions are omitted. With the above, the contact detection process (S3) ends.

[0173] (4) Update processing

[0174] like Figure 7 As shown, when the contact detection process (S3) is completed, the update process (S4) is executed.

[0175] In the quadrature phase component comparison process ( Fig.13 In S30), when the first quadrature phase component Q1 and the modified second quadrature phase component QC2 are within the range of the first quadrature phase error ΔQE1 ( Fig.13 ( S31 : Yes), the quadrature phase component updating unit 35 updates the first quadrature phase component Q1 used for the contact determination unit 33 as the alternative quadrature phase component QA stored in the storage unit 64 .

[0176] In addition, in the in-phase phase component comparison process ( Fig.14 In S40), when the first in-phase component I1 and the modified second in-phase component IC2 are within the range of the first in-phase phase error ΔIE1 ( Fig.14 (S41: Yes), the in-phase component update unit 36 ​​updates the first in-phase component I1 used for the contact determination unit 33 as the alternative in-phase component IA stored in the storage unit 64. The update process (S4) is completed as described above.

[0177] The operations other than those described above are the same as those in Embodiment 1, and thus repeated descriptions are omitted.

[0178] Next, the effect of this method is described. In this method, when noise of a frequency near the first frequency is mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the alternative quadrature phase component QA stored in the storage unit 64. As a result, the influence of noise on the contact detection device 60 can be reduced.

[0179] According to this embodiment, in order to detect contact of a conductor with the first electrode layer 22 of the electrostatic sensor 7 , the in-phase component is used in addition to the above-mentioned quadrature phase component, thereby improving the accuracy of the contact detection device 60 .

[0180] In addition, according to the present method, when the first orthogonal phase component Q1 and the modified second orthogonal phase component QC2 are outside the range of the first orthogonal phase error ΔQE1, and the first in-phase phase component I1 and the modified second in-phase phase component IC2 are outside the range of the first in-phase phase error ΔIE1, the contact of the conductor with the electrostatic sensor 7 can be detected based on the alternative orthogonal phase component QA stored in the storage unit 64 and used in the previous judgment, and the alternative in-phase phase component IA stored in the storage unit 64 and used in the previous judgment.

[0181] In addition, the first frequency of this method is greater than the second frequency. In terms of the nature of impedance, the accuracy of the contact detection device 60 can be improved by applying an AC voltage with a large frequency. Therefore, in the case where the first frequency greater than the second frequency can be used for the detection of the conductor, the accuracy of the contact detection device 60 can be improved. According to this method, in the case where noise with a frequency close to the first frequency is not mixed, the contact of the conductor to the first electrode layer 22 can be detected based on the alternative phase component (alternative orthogonal phase component QA or alternative in-phase phase component IA) stored in the storage unit 64 and used in the previous judgment, so the accuracy of the contact detection device 60 can be improved as much as possible.

[0182] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist of the invention.

[0183] In this method, the orthogonal phase component updating unit 35 and the in-phase phase component updating unit 36 ​​are respectively used to update the replacement orthogonal phase component QA and the replacement in-phase phase component IA, but the present invention is not limited to this. The orthogonal phase component updating unit 35 and the in-phase phase component updating unit 36 ​​can be omitted, and the replacement orthogonal phase component QA and the replacement in-phase phase component IA are initial values ​​stored in the storage unit 64 and can be set to unupdated values.

Claims

1. A contact detection device (10, 60), comprising: An electrostatic sensor (7) having detection electrodes (22, 23) for detecting contact of a conductor; an alternating current power source (11) for applying an alternating current voltage to the detection electrode; a quadrature demodulator (12) for extracting at least the quadrature phase component when the impedance of the electrostatic sensor is represented by an in-phase component and a quadrature phase component, using a signal output from the detection electrode when the AC voltage is applied to the detection electrode; as well as A measuring device (30) detects whether the conductor contacts the electrostatic sensor based on the quadrature phase component extracted by the quadrature demodulator, wherein: The AC power source switches between a first AC voltage of a first frequency and a second AC voltage of a second frequency different from the first frequency and applies the voltages to the detection electrode. The measuring device comprises: a storage unit (34, 64) storing a substitute quadrature phase component (QA) corresponding to a state in which the conductor contacts the electrostatic sensor; an orthogonal phase component comparison unit (31) for comparing a first orthogonal phase component (Q1) extracted by the orthogonal demodulator when the first AC voltage is applied to the detection electrode and a second orthogonal phase component (Q2) extracted by the orthogonal demodulator when the second AC voltage is applied to the detection electrode; and A contact determination unit (33) detects contact of the conductor with the electrostatic sensor based on the first quadrature phase component when the first quadrature phase component and the second quadrature phase component are within a range of a predetermined first quadrature phase error (ΔQE1), and detects contact of the conductor with the electrostatic sensor based on the alternative quadrature phase component stored in the storage unit when the first quadrature phase component and the second quadrature phase component are outside the range of the first quadrature phase error.

2. The contact detection device according to claim 1, wherein: The AC power source switches the first AC voltage and the second AC voltage at a predetermined cycle and applies the voltages to the detection electrode.

3. The contact detection device according to claim 1 or 2, wherein: The substitute quadrature phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device.

4. The contact detection device according to claim 1 or 2, wherein: The measuring device includes an orthogonal phase component updating unit (35) which updates the first orthogonal phase component used in the contact determination unit as the replacement orthogonal phase component stored in the storage unit when the first orthogonal phase component and the second orthogonal phase component are within the range of the first orthogonal phase error. When the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, the contact determination unit detects the contact of the conductor to the electrostatic sensor based on the alternative orthogonal phase component updated by the storage unit and used in the previous determination.

5. The contact detection device according to claim 1 or 2, wherein: The quadrature demodulator extracts the in-phase component and the quadrature-phase component, The measuring device detects whether the conductor is in contact with the electrostatic sensor based on the in-phase component and the quadrature-phase component extracted by the quadrature demodulator. The storage unit stores the substitute in-phase component (IA) and the substitute quadrature-phase component corresponding to the state in which the conductor contacts the electrostatic sensor. The measuring device includes an in-phase component comparison unit (32) for comparing a first in-phase component (I1) extracted by the orthogonal demodulator when the first AC voltage is applied to the detection electrode and a second in-phase component (I2) extracted by the orthogonal demodulator when the second AC voltage is applied to the detection electrode. The contact determination unit detects contact of the conductor with the electrostatic sensor based on the first quadrature phase component and the first in-phase component, when the first quadrature phase component and the second quadrature phase component are within the range of the first quadrature phase error and the first in-phase phase component and the second in-phase phase component are within the range of a predetermined first in-phase phase error (ΔIE1). When the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, and the first in-phase phase component and the second in-phase phase component are outside the range of the first in-phase phase error, the contact determination unit detects the contact of the conductor to the electrostatic sensor based on the alternative orthogonal phase component and the alternative in-phase phase component stored in the storage unit.

6. The contact detection device according to claim 5, wherein: The substitute quadrature phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device. The substitute in-phase phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device.

7. The contact detection device according to claim 5, wherein: The measuring device comprises: an orthogonal phase component updating unit (35) which updates the first orthogonal phase component used in the contact determination unit as the replacement orthogonal phase component stored in the storage unit when the first orthogonal phase component and the second orthogonal phase component are within the range of the first orthogonal phase error; as well as an in-phase component updating unit (36) which updates the first in-phase component used in the contact determination unit as the replacement in-phase component stored in the storage unit when the first in-phase component and the second in-phase component are within the range of the first in-phase phase error, When the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, and the first in-phase phase component and the second in-phase phase component are outside the range of the first in-phase phase error, the contact determination unit detects the contact of the conductor to the electrostatic sensor based on the replacement orthogonal phase component and the replacement in-phase phase component updated by the storage unit and the replacement orthogonal phase component and the replacement in-phase phase component used in the previous determination.

8. The contact detection device according to claim 1 or 2, wherein: The first frequency is greater than the second frequency.

9. The contact detection device according to claim 1, wherein: The AC power source switches the first AC voltage, the second AC voltage, and a third AC voltage having a third frequency different from the first frequency and the second frequency and applies the voltages to the detection electrode. The quadrature phase component comparison unit compares the first quadrature phase component, the second quadrature phase component, and a third quadrature phase component (Q3) extracted by the quadrature demodulator when the third AC voltage is applied to the detection electrode. In a case where the first orthogonal phase component and the second orthogonal phase component are within the range of the first orthogonal phase error, the contact determination unit detects contact of the conductor with the electrostatic sensor based on the first orthogonal phase component, and in a case where the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, the contact determination unit compares the first orthogonal phase component with the third orthogonal phase component, and in a case where the first orthogonal phase component and the third orthogonal phase component are within a predetermined second orthogonal phase error (ΔQE2), the contact determination unit detects contact of the conductor with the electrostatic sensor based on the first orthogonal phase component, and in the When the first orthogonal phase component and the third orthogonal phase component are outside the range of the second orthogonal phase error, the contact determination unit compares the second orthogonal phase component and the third orthogonal phase component, and when the second orthogonal phase component and the third orthogonal phase component are within the range of a predetermined third orthogonal phase error (ΔQE3), the contact determination unit detects contact of the conductor with the electrostatic sensor based on the second orthogonal phase component, and when the second orthogonal phase component and the third orthogonal phase component are outside the range of the third orthogonal phase error, the contact determination unit detects contact of the conductor with the electrostatic sensor based on the replacement orthogonal phase component stored in the storage unit.

10. The contact detection device according to claim 9, wherein: The AC power source switches the first AC voltage, the second AC voltage, and the third AC voltage at a predetermined cycle and applies the voltages to the detection electrode.

11. The contact detection device according to claim 9 or 10, wherein: The substitute quadrature phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device.

12. The contact detection device according to claim 9 or 10, wherein: The measuring device includes an orthogonal phase component updating unit (35) which updates the first orthogonal phase component used in the contact determination unit as the substitute orthogonal phase component stored in the storage unit when the first orthogonal phase component and the second orthogonal phase component are within the range of the first orthogonal phase error, updates the first orthogonal phase component used in the contact determination unit as the substitute orthogonal phase component stored in the storage unit when the first orthogonal phase component and the third orthogonal phase component are within the range of the second orthogonal phase error, and updates the second orthogonal phase component used in the contact determination unit as the substitute orthogonal phase component stored in the storage unit when the second orthogonal phase component and the third orthogonal phase component are within the range of the third orthogonal phase error, When the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, and when the first orthogonal phase component and the third orthogonal phase component are outside the range of the second orthogonal phase error, and when the second orthogonal phase component and the third orthogonal phase component are outside the range of the third orthogonal phase error, the contact determination unit detects contact of the conductor with the electrostatic sensor based on the alternative orthogonal phase component updated in the storage unit and used in the previous determination.

13. The contact detection device according to claim 9 or 10, wherein: The quadrature demodulator extracts the in-phase component and the quadrature-phase component, The measuring device detects whether the conductor is in contact with the electrostatic sensor based on the in-phase component and the quadrature-phase component extracted by the quadrature demodulator. The storage unit stores the substitute in-phase component and the substitute quadrature-phase component corresponding to the state in which the conductor contacts the electrostatic sensor. The measuring device includes an in-phase component comparison unit (32) for comparing a first in-phase component extracted by the orthogonal demodulator when the first AC voltage is applied to the detection electrode, a second in-phase component extracted by the orthogonal demodulator when the second AC voltage is applied to the detection electrode, and a third in-phase component (I3) extracted by the orthogonal demodulator when the third AC voltage is applied to the detection electrode. The contact determination unit detects contact of the conductor with the electrostatic sensor based on the first quadrature phase component and the first in-phase component, when the first quadrature phase component and the second quadrature phase component are within the range of the first quadrature phase error and the first in-phase phase component and the second in-phase phase component are within the range of a predetermined first in-phase phase error (ΔIE1). When the first quadrature phase component and the third quadrature phase component are within the range of the second quadrature phase error, and the first in-phase phase component and the third in-phase phase component are within the range of a predetermined second in-phase phase error (ΔIE2), the contact determination unit detects contact of the conductor with the electrostatic sensor based on the first quadrature phase component and the first in-phase phase component. The contact determination unit detects contact of the conductor with the electrostatic sensor based on the second quadrature phase component and the second in-phase phase component, when the second quadrature phase component and the third quadrature phase component are within the range of the third quadrature phase error, and the second in-phase phase component and the third in-phase phase component are within the range of a predetermined third in-phase phase error (ΔIE3). When the first orthogonal phase component and the second orthogonal phase component are outside the range of the first orthogonal phase error, and the first in-phase phase component and the second in-phase phase component are outside the range of the first in-phase phase error, and when the first orthogonal phase component and the third orthogonal phase component are outside the range of the second orthogonal phase error, and the first in-phase phase component and the third in-phase phase component are outside the range of the second in-phase phase error, and when the second orthogonal phase component and the third orthogonal phase component are outside the range of the third orthogonal phase error, and the second in-phase phase component and the third in-phase phase component are outside the range of the third in-phase phase error, the contact determination unit detects contact of the conductor with the electrostatic sensor based on the alternative orthogonal phase component and the alternative in-phase phase component stored in the storage unit.

14. The contact detection device according to claim 13, wherein: The substitute quadrature phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device. The substitute in-phase phase component is an initial value stored in advance in the storage unit and is a value that is not updated during contact detection by the measuring device.

15. The contact detection device according to claim 13, wherein: The measuring device includes an in-phase component updating unit (36) which updates the first in-phase component used in the contact determination unit as the substitute in-phase component stored in the storage unit when the first in-phase component and the second in-phase component are within the range of the first in-phase phase error, updates the first in-phase component used in the contact determination unit as the substitute in-phase component stored in the storage unit when the first in-phase component and the third in-phase component are within the range of the second in-phase phase error, and updates the second in-phase component used in the contact determination unit as the substitute in-phase component stored in the storage unit when the second in-phase component and the third in-phase component are within the range of the third in-phase phase error. When the first in-phase phase component and the second in-phase phase component are outside the range of the first in-phase phase error, and when the first in-phase phase component and the third in-phase phase component are outside the range of the second in-phase phase error, and when the second in-phase phase component and the third in-phase phase component are outside the range of the third in-phase phase error, the contact determination unit detects the contact of the conductor to the electrostatic sensor based on the alternative in-phase phase component updated in the storage unit and used in the previous determination.

16. The contact detection device according to claim 9 or 10, wherein: The first frequency is greater than the second frequency, and the second frequency is greater than the third frequency.

17. The contact detection device according to claim 16, wherein: The first frequency is 100-150 kHz.

18. The contact detection device according to claim 17, wherein: The second frequency is 50-100 kHz.

19. The contact detection device according to claim 18, wherein: The third frequency is 5 to 50 kHz.

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