阅读说明：本技术 静电电容检测传感器 (Electrostatic capacitance detection sensor ) 是由 山田朋辉 于 2020-03-13 设计创作，主要内容包括：一种基于自电容方式的静电电容检测传感器,具有：第一电极；第二电极；感测信号产生部,将所述第一电极或所述第二电极之中的一方作为感测电极,使向所述感测电极施加的感测信号产生；和检测部,将所述感测电极中的与静电电容对应的电荷的移动量检测为检测值,将所述第一电极或所述第二电极之中的另一方设为驱动电极,在向所述驱动电极施加第一驱动信号的状态下和施加频率相同、相位不同的第二驱动信号的状态下,基于所述检测部中的检测值的差分,判定检测对象是否接近所述第一电极以及所述第二电极双方,由此解决上述课题。(A self-capacitance-type electrostatic capacitance detection sensor includes: a first electrode; a second electrode; a sensing signal generating unit configured to generate a sensing signal applied to the sensing electrode by using one of the first electrode and the second electrode as the sensing electrode; and a detection unit that detects a movement amount of electric charge corresponding to the capacitance in the sensing electrode as a detection value, and that uses the other of the first electrode and the second electrode as a drive electrode, and determines whether or not a detection object is in proximity to both the first electrode and the second electrode based on a difference between the detection values in the detection unit in a state where a first drive signal is applied to the drive electrode and in a state where a second drive signal having the same frequency and a different phase is applied to the drive electrode.)

1. A capacitance detection sensor based on a self-capacitance method includes:

a first electrode;

a second electrode;

a sensing signal generating unit configured to generate a sensing signal applied to the sensing electrode by using one of the first electrode and the second electrode as the sensing electrode; and

a detection section that detects a movement amount of electric charge in the sensing electrode corresponding to the electrostatic capacitance as a detection value by applying the sensing signal to the sensing electrode by the sensing signal generation section,

the electrostatic capacity detection sensor is characterized in that,

the other of the first electrode and the second electrode is used as a driving electrode,

the detection device includes a determination unit configured to determine whether or not a detection target approaches both the first electrode and the second electrode based on a difference between a first detection value detected by the detection unit in a state where a first drive signal is applied to the drive electrode and a second detection value detected by the detection unit in a state where a second drive signal having the same frequency and a different phase from the first drive signal is applied to the drive electrode.

2. The electrostatic capacitance detection sensor according to claim 1,

the first drive signal is the same signal as the sense signal,

the second drive signal is a drive signal that,

having a drive signal control section that selects the sense signal or the drive signal and applies it to the drive electrode,

the drive signal control unit includes:

a drive signal generation unit that generates the drive signal; and

and a selection unit connected to the sensing signal generation unit and the driving signal generation unit, and selecting the sensing signal or the driving signal.

3. The electrostatic capacitance detection sensor according to claim 1,

a drive signal control section for selecting the first drive signal or the second drive signal and applying the selected drive signal to the drive electrode,

the drive signal control unit includes:

a first drive signal generation unit that generates the first drive signal;

a second drive signal generation unit that generates the second drive signal; and

a selection unit that selects the first drive signal or the second drive signal.

4. The electrostatic capacitance detection sensor according to any one of claims 1 to 3,

the determination unit determines that the detection target approaches both the first electrode and the second electrode when the value of the difference exceeds a predetermined first threshold value.

5. The electrostatic capacitance detection sensor according to any one of claims 1 to 4,

the electrostatic capacitance detection sensor further includes a shield electrode provided between the sensing electrode and the drive electrode, and to which the sensing signal is applied.

6. The electrostatic capacitance detection sensor according to any one of claims 1 to 5,

the first drive signal is 180 ° out of phase with the second drive signal.

7. The electrostatic capacitance detection sensor according to any one of claims 1 to 6,

the distance between the sensing electrode and the driving electrode is less than or equal to 1 m.

8. The electrostatic capacitance detection sensor according to any one of claims 1 to 7,

the sensing electrode and the driving electrode are mounted to a steering wheel,

one of the sensing electrode and the driving electrode is attached to a front side of the steering wheel, and the other is attached to a rear side of the steering wheel.

9. The electrostatic capacitance detection sensor according to any one of claims 1 to 8,

a drive sense selection unit having one of the first electrode and the second electrode as the sense electrode and the other as the drive electrode,

the determination unit determines that the detection object is close to both the first electrode and the second electrode when a difference between a value of the difference obtained in a state where the first electrode is a sense electrode and the second electrode is a drive electrode and a value of the difference obtained in a state where the second electrode is a sense electrode and the first electrode is a drive electrode is equal to or less than a predetermined second threshold value.

10. The electrostatic capacitance detection sensor according to any one of claims 1 to 9,

a plurality of said drive electrodes are provided.

11. The electrostatic capacitance detection sensor according to any one of claims 1 to 10,

three or more electrodes including the first electrode and the second electrode are provided,

the sensing electrode and the driving electrode are selected from among the three or more electrodes.

Technical Field

The present invention relates to an electrostatic capacitance detection sensor.

Background

In recent years, as a technique related to automatic driving (autonomus), a hod (handles on detection) sensor has been developed. The HoD sensor detects a held state of a steering wheel, for example, and when a capacitance detection sensor is used, for example, a certain value is used as a reference value, and when the detected value of capacitance or the like exceeds the reference value, it can be determined that the steering wheel is touched (held), and when the detected value is equal to or less than the reference value, it is determined that the steering wheel is not touched (not held).

Prior art documents

Patent document

Patent document 1: japanese patent No. 6177026

Patent document 2: japanese patent laid-open publication No. 2015-232542

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional method, for example, erroneous detection may occur in which a hand of a person to be detected holds the steering wheel and the like but is determined not to hold or is determined to be holding without holding, and it is difficult to accurately determine whether or not the steering wheel is held.

Therefore, a capacitance detection sensor capable of accurately determining whether or not a detection target is being held is required.

Means for solving the problems

According to an aspect of the present embodiment, there is provided a capacitance detection sensor based on a self-capacitance method, including: a first electrode; a second electrode; a sensing signal generating unit configured to generate a sensing signal applied to the sensing electrode by using one of the first electrode and the second electrode as the sensing electrode; and a detection unit configured to detect a movement amount of the charge corresponding to the capacitance in the sensing electrode as a detection value by applying the sensing signal to the sensing electrode by the sensing signal generation unit, wherein the other of the first electrode or the second electrode is a drive electrode, and a determination unit configured to determine whether or not a detection object is in proximity to both the first electrode and the second electrode based on a difference between a first detection value detected by the detection unit in a state where a first drive signal is applied to the drive electrode and a second detection value detected by the detection unit in a state where a second drive signal having the same frequency and a different phase from the first drive signal is applied to the drive electrode is provided.

Effect of invention

According to the disclosed capacitance detection sensor, whether or not the detection object is held can be accurately determined.

Drawings

Fig. 1 is a configuration diagram of a self-capacitance detection sensor.

Fig. 2 is a configuration diagram of the electrostatic capacity detection sensor in the first embodiment.

Fig. 3 is a flowchart of a detection method of the electrostatic capacity detection sensor in the first embodiment.

Fig. 4 is an explanatory diagram of the electrostatic capacity detection sensor according to the first embodiment.

Fig. 5 is a diagram (1) illustrating an experiment relating to the electrostatic capacity detection sensor according to the first embodiment.

Fig. 6 is an explanatory diagram (2) of an experiment relating to the electrostatic capacity detection sensor according to the first embodiment.

Fig. 7 is a configuration diagram of a capacitance detection sensor according to modification 1 of the first embodiment.

Fig. 8 is a configuration diagram of a modification 2 of the capacitance detection sensor according to the first embodiment.

Fig. 9 is a configuration diagram of the electrostatic capacity detection sensor in the second embodiment.

Fig. 10 is a configuration diagram (1) of the electrostatic capacity detection sensor in the second embodiment.

Fig. 11 is a configuration diagram (2) of the electrostatic capacity detection sensor in the second embodiment.

Fig. 12 is a flowchart of a detection method of the electrostatic capacity detection sensor in the second embodiment.

Fig. 13 is an explanatory view of a steering wheel in the third embodiment.

Fig. 14 is an explanatory diagram of a door handle in the third embodiment.

Fig. 15 is an explanatory diagram of a smartphone according to the third embodiment.

Detailed Description

The following describes embodiments for implementation. The same members and the like are given the same reference numerals, and description thereof is omitted.

[ first embodiment ]

First, a case of performing detection using a self-capacitance type electrostatic capacitance detection sensor will be described with reference to fig. 1. The self-capacitance type electrostatic capacitance detection sensor shown in fig. 1 includes a sensor portion 10 and a circuit portion 20, and the sensor portion 10 includes a sensing electrode 11. The circuit unit 20 includes a sensing signal generating unit 30, a detecting unit 40, a contact determining unit 50, a control unit 70, and the like, and the contact determining unit 50 includes a memory 51 and a determining unit 52.

In the electrostatic capacitance detection sensor, a drain capacitance C is generated between the sense electrode 11 and GND_L1An electrostatic capacitance C is generated between a part 81 of a human body 80 as a detection object and the sensing electrode 11_F1. When a part 81 of the human body 80 approaches the sensing electrode 11, the electrostatic capacitance C_F1The value of (a) increases. In addition, a coupling capacitance C is generated between the human body 80 and GND_FG. The part 81 of the human body 80 is, for example, a finger or a palm.

In this capacitance detection sensor, when an alternating voltage is applied to the sensing electrode 11 by the sensing signal generating unit 30 and a part 81 of the human body 80 approaches the sensing electrode 11, the capacitance C is set to be equal to or larger than the capacitance C_F1The amount of charge moved accompanying this, i.e., the amount of movement of the charge, increases. The value of the amount of movement of the charge is detected by the detection unit 40, and the value is stored in the memory 51. The determination unit 52 determines whether or not the value of the amount of movement of the electric charge detected by the detection unit 40 stored in the memory 51 exceeds a predetermined threshold value, and determines whether or not the part 81 of the human body 80 touches the sensor unit 10. Specifically, the determination unit 52 determines that the part 81 of the human body 80 touches the sensor unit 10 when the value of the amount of movement of the electric charge exceeds a predetermined threshold value, and determines that the part does not exceed the predetermined threshold valueThe contact or non-contact information is output when a part 81 of the human body 80 does not touch the sensor unit 10. The control unit 70 controls the series of electrostatic capacitance detection operations described above.

In general, a portion for sensing contact with the sensor unit 10 is formed of an insulator covering the sensing electrode 11. That is, when the part 81 of the human body 80 touches the sensor unit 10, the part 81 of the human body 80 approaches the sensing electrode 11 via the insulator. In the present invention described below, the sensing electrode and the driving electrode are provided at positions separated by an insulator, and a part of a human body does not directly touch these electrodes.

However, in the case of the self-capacitance type capacitance detection sensor shown in fig. 1, the capacitance may vary due to environmental changes, such as temperature changes, external factors, and the like, and thus erroneous detection may occur. Specifically, there are the following cases: even if the part 81 of the human body 80 does not touch the sensor unit 10, the electrostatic capacitance is detected to be large in the detection unit 40, and the determination unit 52 determines that the part 81 of the human body 80 touches the sensor unit 10; even if part 81 of human body 80 touches sensor unit 10, the capacitance is detected to be small in detection unit 40, and determination unit 52 determines that part 81 of human body 80 does not touch sensor unit 10.

Although various studies have been made to eliminate the false detection as described above, any method cannot sufficiently suppress the false detection. Therefore, a capacitance detection sensor that does not detect erroneously is desired.

(capacitance detecting sensor)

Next, an electrostatic capacitance detection sensor according to a first embodiment will be described with reference to fig. 2. The capacitance detection sensor in the present embodiment is a self-capacitance type capacitance detection sensor, and includes a sensor portion 110 and a circuit portion 120, in which the sensor portion 110 includes a sensing electrode 111 and a driving electrode 112. The capacitance detection sensor in the present embodiment is used to determine whether or not a predetermined portion of the sensor portion 110 is held by a human hand or the like. The circuit unit 120 includes a sensing signal generating unit 130, a detecting unit 140, a holding determination unit 150, a drive signal control unit 160, a control unit 170, and the like, and the holding determination unit 150 includes a memory 151 and a determination unit 152. The drive signal control unit 160 includes a drive signal generation unit 161 and a switch 162 serving as a selection unit for selecting a signal to be applied to the drive electrode 112.

In the present application, the sensing electrode 111 and the driving electrode 112 may be referred to as a first electrode and a second electrode, and in this case, one of the first electrode and the second electrode is the sensing electrode 111 and the other is the driving electrode 112. In other words, the capacitance detection sensor in the present embodiment has a first electrode and a second electrode. Further, a plurality of sensing electrodes 111 may be provided and one of them may be selected, or a plurality of driving electrodes 112 may be provided and one of them may be selected. In addition, three or more electrodes including the first electrode and the second electrode may be provided, and the sensing electrode and the driving electrode may be selected from among the three or more electrodes.

In the electrostatic capacitance detection sensor in the present embodiment, the drain capacitance C is generated between the sense electrode 111 and the GND_L1An electrostatic capacitance C is generated between the part 81 of the human body 80 as the detection object and the sensing electrode 111_F1When a part 81 of the human body 80 approaches the sensing electrode 111, the capacitance C_F1The value of (a) increases. In addition, an electrostatic capacitance C is generated between the other portion 82 of the human body 80 and the drive electrode 112_F2When another part 82 of the human body 80 approaches the drive electrode 112, the capacitance C_F2The value of (a) increases. In the present embodiment, since the condition that the one portion 81 and the other portion 82 of the same human body 80 simultaneously approach the sensing electrode 111 and the driving electrode 112 is detected, the distance between the sensing electrode 111 and the driving electrode 112 is preferably 1m or less.

In addition, an electrostatic capacitance C is generated between the sensing electrode 111 and the driving electrode 112_SDHowever, the present embodiment is premised on the fact that the electric charges of the driving electrode 112 affect the sensing electrode 111 through the other part 82 of the human body, the human body 80, and the one part 81 of the human bodySound, therefore, the electrostatic capacitance C is preferable_SDThe value of (c) is as small as possible. In the description herein, the electrostatic capacitance C_SDTo the extent that it can be ignored.

In the electrostatic capacitance detection sensor according to the present embodiment, the sensing signal generating unit 130 generates a sensing signal applied to the sensing electrode 111, and applies the sensing signal to the sensing electrode 111 as an alternating voltage. Here, when a part 81 of the human body 80 approaches the sensing electrode 111, the capacitance C is set to be equal to or larger than the predetermined value_F1The value of (b) increases, and therefore, the amount of movement of the charge also increases in association therewith. That is, by applying a sensing signal to the sensing electrode 111 by the sensing signal generating section 130, the detecting section 140 detects a moving amount of the charge corresponding to the electrostatic capacitance in the sensing electrode 111 as a detection value, and stores the detection value in the memory 151. The determination unit 152 determines whether to hold or not to hold based on the detection value stored in the memory 151 and outputs the determination result. Specifically, the determination unit 152 determines whether or not the detection target is close to both the first electrode and the second electrode based on the difference between the first detection value detected by the detection unit 140 in a state where the first drive signal is applied to the drive electrode 112 and the second detection value detected by the detection unit 140 in a state where the second drive signal having the same frequency but a different phase from the first drive signal is applied to the drive electrode 112. The specific method is described later, but here, the first driving signal is the same signal as the sensing signal. Note that the second drive signal is the same signal as the drive signal generated in the drive signal generation section 161. The control unit 170 controls the series of electrostatic capacitance detection operations described above.

Further, the driving signal control section 160 selects a sensing signal or a driving signal and applies it to the driving electrode 112. Specifically, the drive signal generating section 161 provided in the drive signal control section 160 generates a drive signal. A switch 162 provided in the drive signal control section 160 is connected to the drive electrode 112 and to the sense signal generation section 130 and the drive signal generation section 161, and switches a connection destination corresponding to the drive electrode 112 between the sense signal generation section 130 and the drive signal generation section 161 to select a signal to be applied to the drive electrode 112. That is, the switch 162 provided in the driving signal control section 160 selects the sensing signal generated in the sensing signal generating section 130 or the driving signal generated in the driving signal generating section 161 and outputs to the driving electrode 112. That is, the sensing signal generating part 130 is connected to the driving signal control part 160. In the present embodiment, the ac sense signal output from the sense signal generator 130 and the ac drive signal output from the drive signal generator 161 have the same frequency but are shifted in phase by 180 °. The sensing signal and the driving signal may be at least out of phase, but it is preferable because the detection accuracy is improved when the phase is out of phase by 180 °.

(detection method)

Next, description will be made based on fig. 3: the capacitance detection sensor in the present embodiment is used as a detection method for determining whether or not the sensor unit 110 is held by a hand of a person or the like.

First, in step 102(S102), the circuit section 120 applies a sense signal generated in the sense signal generation section 130 to the drive electrode 112 in a state where the sense signal is applied to the sense electrode 111. Specifically, the sensing signal generating part 130 generates and applies a sensing signal to the sensing electrode 111. In this state, the switch 162 of the driving signal control part 160 selects the sensing signal by connecting the sensing signal generating part 130 and the driving electrode 112, and applies the sensing signal to the driving electrode 112. The control unit 170 performs control of the timing of these operations, the detection timing by the detection unit 140, and the holding determination timing by the holding determination unit 150.

Next, in step 104(S104), in a state where the sensing signal is applied to the sensing electrode 111 and the driving electrode 112, the detection unit 140 detects a moving amount of the charge corresponding to the electrostatic capacitance in the sensing electrode 111 as a detection value V_d1And stored in the memory 151. The detection value V_d1The value is represented by the following numerical formula 1.

[ numerical formula 1]

Next, in step 106(S106), the driving signal control part 160 applies the driving signal generated in the driving signal generation part 161 to the driving electrode 112 in a state where the sensing signal generated in the sensing signal generation part 130 is applied to the sensing electrode 111. Specifically, in a state where the sensing signal generated in the sensing signal generating section 130 is applied to the sensing electrode 111, the switch 162 in the driving signal control section 160 selects the driving signal by connecting the driving signal generating section 161 and the driving electrode 112, and applies the driving signal to the driving electrode 112.

Next, in step 108(S108), a sensing signal is applied to the sensing electrode 111, and the detection unit 140 detects a moving amount of the charge corresponding to the electrostatic capacitance in the sensing electrode 111 as a detection value V in a state where the driving signal is applied to the driving electrode 112_d2And stored in the memory 151. The detection value V_d2The value is expressed by the following numerical formula 2. The sensing signal and the driving signal are opposite-phase signals having a phase deviation of 180 °, and thus the human body 80 passes through C_F2And slightly shakes in opposite phases, and the detection value V_d2The detected value V is shown in equation 1_d1A different value.

[ numerical formula 2]

Next, in step 110(S110), determining unit 152 determines from detection value V stored in memory 151_d1And the detected value V_d2Calculating a difference V_d2-V_d1. The calculated difference V_d2-V_d1The value is represented by the following equation 3. The calculated difference V is shown in equation 3_d2-V_d1Is connected with an electrostatic capacitance C_F1And an electrostatic capacitance C_F2A value proportional to the product of the capacitance C_F1And an electrostatic capacitance C_F2Both sides only increase in value at a sufficiently large value. Therefore, in the case where the part 81 of the human body 80 approaches only the sensing electrode 111 or approaches only the sensing electrode 111In the case of the drive electrode 112, the difference V_d2-V_d1The value of (a) is extremely small. Therefore, the difference V is only obtained when the part 81 of the human body 80 approaches both the sensing electrode 111 and the driving electrode 112, that is, only when the part 81 of the human body 80 holds the part of the sensor unit 110 where the sensing electrode 111 and the driving electrode 112 are provided_d2-V_d1The value of (a) increases. The electrostatic capacitance detection sensor of the self-capacitance type in the related art generally does not have a drive electrode. However, the capacitance detection sensor of the present invention is a self-capacitance type sensor including a drive electrode 112 which does not originally exist, two types of signals having the same frequency but different phases are sequentially applied to the drive electrode 112, and the capacitance of the sense electrode 111 in each case is detected, whereby the capacitance C can be extracted_F1And an electrostatic capacitance C_F2The aspect of the product proportional value has a great advantage.

[ numerical formula 3]

Next, in step 112(S112), determination unit 152 determines difference V_d2-V_d1Is greater than a given first threshold Th. Determining unit 152 determines difference V_d2-V_d1When the value of (d) exceeds a predetermined first threshold value Th, it is determined that the detection target approaches both the first electrode (sensing electrode 111) and the second electrode (driving electrode 112). That is, the process proceeds to step 114(S114) to determine that the information is being held, and determination unit 152 outputs the information being held and ends. In addition, at the difference V_d2-V_d1If the value of (d) is equal to or less than the predetermined first threshold value Th, the process proceeds to step 116(S116) to determine that the information is not held, and the determination unit 152 outputs the information not held and ends.

As described above, the difference V shown in equation 3_d2-V_d1In the case of only approaching the sensing electrode 111, or only approaching the driving electrode 112, the value is extremely small; only when the detection object approaches both of the sensing electrode 111 and the driving electrode 112, that is, the human body 8The value of 0 increases when the portion 81 of the sensor portion 110 where the sensing electrode 111 and the driving electrode 112 are provided is held. Therefore, the determination unit 152 can accurately determine whether or not the sensor unit 110 holds the portion where the sensing electrode 111 and the driving electrode 112 are provided.

In addition, the difference V shown in equation 3_d2-V_d1Since there is no leakage capacitance C whose value varies due to temperature change or the like_L1And therefore there is no dependence on environmental changes based on temperature and the like. Therefore, the predetermined first threshold Vth does not need to be changed depending on the environment such as temperature, and can be fixed to the predetermined first threshold Vth. Therefore, even when the power supply of the capacitance detection sensor is turned on in a state where a predetermined portion of the sensor portion 110 is held, the obtained difference V is only required_d2-V_d1When the value of (d) exceeds a predetermined first threshold value Th, the determination unit 152 can determine that the portion of the sensor unit 110 where the sensing electrode 111 and the driving electrode 112 are provided is held.

As shown in fig. 4, in the capacitance detection sensor according to the present embodiment, when different human bodies approach the sensing electrode 111 and the driving electrode 112, the determination unit 152 does not determine the portion of the sensor unit 110 where the sensing electrode 111 and the driving electrode 112 are provided. Specifically, when a part 81 of the human body 80 approaches the sensing electrode 111 and a part 181 of the human body 180 different from the human body 80 approaches the driving electrode 112, the human body 80 is not affected by the change in the driving signal. Therefore, the detection value V in the case where the sensing signal is applied to the drive electrode 112_d1And a detection value V in the case where a drive signal is applied to the drive electrode 112_d2Are the same value, so the difference V_d2-V_d1The value of (a) is extremely small. Therefore, the determination unit 152 does not determine the portion of the sensor unit 110 where the sensing electrode 111 and the driving electrode 112 are provided.

This is as C_F1、C_F2、C_FG、C_L1Is on the pair detection value V_d1In the case of detection and on the detected value V_d2It is preferable that the detection value V is not changed when the detection is performed_d1Detection of the pair detection value V is performed_d2The time taken for detection is as short as possible.

In addition, the detected value V_d1And a detection value V_d2The denominator of (A) includes a coupling capacitance C between the human body and GND_FGCoupling capacitor C_FGRelative to the electrostatic capacitance C generated by holding_F1、C_F2When the difference is overwhelmingly large, the difference V may be_d2-V_d1The value of (c) does not become large.

(results of experiments)

Next, an experiment performed using a test apparatus in which the sensing electrode 111 and the driving electrode 112 are provided on the surface of the substrate 190 shown in fig. 5 will be described with respect to the electrostatic capacitance detection sensor in the present embodiment. In the test apparatus, the sensing electrode 111 and the driving electrode 112 are covered with an insulator, and the part 81 of the human body 80 does not directly contact with the electrodes.

As shown in fig. 6, during the period from time T1 to time T2, part 81 of human body 80 is close to sensing electrode 111, but is not close to driving electrode 112. In this state, although the value V is detected_d1And a detection value V_d2Rises together with the value of (V), but the detected value V_d1And the detected value V_d2Are substantially the same, so the difference V_d2-V_d1Becomes a value close to 0.

In the period from time T3 to time T4, the sensing electrode 111 is not approached, but the other part 82 of the human body 80 is approached to the driving electrode 112. In this state, since none of them is close to the sensing electrode 111, the detection value V is detected_d1And a detection value V_d2Both values of (A) do not change, so the difference V_d2-V_d1Is approximately 0.

During the period from time T5 to time T6, a part 81 of the human body 80 approaches the sensing electrode 111, and another part 82 of the same human body 80 approaches the driving electrode 112. In this state, the detection value V_d1And a detection value V_d2Are increased together but comparedAt the detection value V_d1A value of (1), a detection value V_d2Is greater, so the difference V_d2-V_d1The value of (a) is greatly increased.

In the period from time T7 to time T8, the rod 182 made of brass, which is different from the human body 80, is in a state of being close to the drive electrode 112, although it is not in a state of being close to the sense electrode 111. In this state, since none of them is close to the sensing electrode 111, the detection value V is detected_d1And a detection value V_d2Is not changed, thereby differentiating V_d2-V_d1Is approximately 0.

In the period from time T8 to time T9, the part 81 of the human body 80 is brought close to the sensing electrode 111, and the brass bar 182 is brought close to the driving electrode 112. In this state, since the part of the human body 80 is not the other part of the human body 80 or the like in proximity to the drive electrode 112, the detection value V is detected by bringing the part 81 of the human body 80 into proximity to the sense electrode 111_d1And a detection value V_d2Rises together with the value of (V), but the detected value V_d1And the detected value V_d2Are substantially the same, so the difference V_d2-V_d1Becomes a value close to 0.

In addition, the state is such that the sensor electrode 111 and the drive electrode 112 are not close to each other in the period from time T0 to time T1, the period from time T2 to time T3, the period from time T4 to time T5, the period from time T6 to time T7, and the period from time T9. In this state, since none of them is close to the sensing electrode 111, the detection value V is detected_d1And a detection value V_d2Is not changed, thereby differentiating V_d2-V_d1Becomes 0.

As described above, as in the period from time T5 to time T6, it can be confirmed that: in a state where a part 81 of the human body 80 approaches the sensing electrode 111 and another part 82 of the same human body 80 approaches the driving electrode 112, the difference V_d2-V_d1The value of (a) is greatly increased. In addition, at times T1, T2, T6, T8, and T9, the difference V is_d2-V_d1The value of (c) is increased instantaneously, and the difference V can be obtained by appropriately setting the length of time for detection_d2-V_d1The component of (a) is removed which momentarily increases.

(modification 1)

Next, a modified example 1 of the capacitance detection sensor according to the present embodiment will be described with reference to fig. 7. As shown in fig. 7, the electrostatic capacitance detection sensor according to the present modification includes a shield electrode 113 provided between a sense electrode 111 and a drive electrode 112. A sensing signal (i.e., a first driving signal) is applied to the shield electrode 113 through the sensing signal generating part 130. Thereby, the electrostatic capacitance C between the sensing electrode 111 and the driving electrode 112 can be reduced_SD。

Therefore, the present modification is preferably applied to the electrostatic capacitance C between the sensing electrode 111 and the driving electrode 112_SDThe value of (c) cannot be ignored, and the like.

(modification 2)

Next, a modified example 2 of the capacitance detection sensor according to the present embodiment will be described with reference to fig. 8. As shown in fig. 8, the capacitance detection sensor according to the present modification includes a first drive signal generation unit 163 and a second drive signal generation unit 164 in a drive signal control unit 160, and both of them are connected to a switch 162. The first drive signal generating section 163 generates a first drive signal. The second drive signal generating section 164 generates a second drive signal. The switch 162 can select either the first drive signal or the second drive signal and apply it to the drive electrode 112. The first drive signal generated by the first drive signal generation unit 163 and the second drive signal generated by the second drive signal generation unit 164 are out of phase by 180 ° and in opposite phase. The first drive signal and the second drive signal may be at least out of phase, but it is preferable that the detection accuracy is improved if the phase is out of phase by 180 °.

In the present modification, the sensing signal generating unit 130 is not connected to the driving signal control unit 160. However, the sense signal generated in the sense signal generating section 130 and either the first drive signal or the second drive signal may be the same signal. In this case, as shown in fig. 2, the first drive signal generating unit 163 can be omitted by connecting the sense signal generating unit 130 to the drive signal control unit 160. In this case, the second drive signal generating section 164 corresponds to the drive signal generating section 161.

[ second embodiment ]

Next, as shown in fig. 9, the sensor portion 210 of the electrostatic capacity detection sensor according to the second embodiment includes a first electrode 211 and a second electrode 212. In this embodiment, one of the first electrode 211 and the second electrode 212 serves as a sensing electrode, and the other serves as a driving electrode.

The circuit unit 220 includes a sensing signal generating unit 130, a detecting unit 140, a holding determination unit 150, a driving signal control unit 160, a control unit 170, a driving sensing selection unit 230, and the like. The holding determination unit 150 includes a memory 151 and a determination unit 152. The driving sensing selection unit 230 uses one of the first electrode 211 and the second electrode as a sensing electrode and the other as a driving electrode. That is, the drive sense selecting section 230 can select the following case: a case where the sensing signal generation part 130 and the driving signal control part 160 are connected in parallel with the first electrode 211 and the second electrode 212; and a case where the sensing signal generating part 130 and the driving signal control part 160 are cross-connected to the first electrode 211 and the second electrode 212.

In the case where the driving sensing selection part 230 is connected in parallel, as shown in fig. 10, the first electrode 211 is connected to the sensing signal generation part 130, and the second electrode 212 is connected to the driving signal control part 160. In this case, the first electrode 211 serves as a sensing electrode, and the second electrode 212 serves as a driving electrode.

In addition, in the case where the driving sensing selection unit 230 is connected in a cross manner, as shown in fig. 11, the first electrode 211 is connected to the driving signal control unit 160, and the second electrode 212 is connected to the sensing signal generation unit 130. In this case, the first electrode 211 serves as a drive electrode, and the second electrode 212 serves as a sense electrode.

In the present embodiment, the electrostatic capacity detection sensor of the present embodiment can improve the accuracy in determining whether or not to hold in the determination section 152 by switching between the sense electrode and the drive electrode in the drive sense selection section 230 in the first electrode 211 and the second electrode 212.

As in the first embodiment, the determination unit 152 determines whether or not the detection target is close to both the first electrode and the second electrode based on the difference between the first detection value detected by the detection unit 140 in a state where the first drive signal is applied to the drive electrode and the second detection value detected by the detection unit 140 in a state where the second drive signal having the same frequency but a different phase from the first drive signal is applied to the drive electrode. A specific method will be described later, but here, it is assumed that the first drive signal is the same signal as the sense signal generated in the sense signal generating section 130. Note that the second drive signal is the same signal as the drive signal generated in the drive signal generation section 161.

Furthermore, when the difference between the value of the difference obtained in the state where the first electrode 211 is a sense electrode and the second electrode 212 is a drive electrode and the value of the difference obtained in the state where the second electrode 212 is a sense electrode and the first electrode 211 is a drive electrode is equal to or less than a predetermined second threshold value, the determination unit 152 determines that the detection target is close to both the first electrode 211 and the second electrode 212.

(detection method)

Next, description will be made based on fig. 12: the capacitance detection sensor in the present embodiment is used as a detection method for determining whether or not the sensor unit 210 is held by a hand of a person or the like. In addition, the sensing signal and the driving signal are inverted signals that are 180 ° out of phase.

First, in step 202(S202), as shown in fig. 10, the drive sense selection unit 230 connects in parallel: the first electrode 211 is connected to the sensing signal generating unit 130, and the second electrode 212 is connected to the driving signal control unit 160. Thus, the first electrode 211 serves as a sensing electrode, and the second electrode 212 serves as a driving electrode.

Next, in step 204(S204), in a state where the sense signal generated in the sense signal generation section 130 is applied to the first electrode 211 serving as the sense electrode, the drive signal control section 160 also applies the sense signal to the second electrode 212 serving as the drive electrode. Specifically, in a state where the sensing signal generated in the sensing signal generating section 130 is applied to the first electrode 211, the switch 162 in the driving signal control section 160 applies the sensing signal to the second electrode 212 by connecting the sensing signal generating section 130 to the second electrode 212.

Next, in step 206(S206), in a state where the sensing signals are applied to the first electrode 211 and the second electrode 212, the detection unit 140 detects a movement amount of the electric charge corresponding to the electrostatic capacitance in the first electrode 211 as the sensing electrode as a detection value Vs1d1, and stores the detection value in the memory 151.

Next, in step 208(S208), in a state where the sense signal generated in the sense signal generation section 130 is applied to the first electrode 211 which becomes the sense electrode, the drive signal control section 160 applies the drive signal generated in the drive signal generation section 161 to the second electrode 212 which becomes the drive electrode. Specifically, in a state where the sensing signal generated in the sensing signal generating section 130 is applied to the first electrode 211, the switch 162 in the driving signal control section 160 connects the driving signal generating section 161 to the second electrode 212, thereby applying the driving signal to the second electrode 212.

Next, in step 210(S210), in a state where the sensing signal is applied to the first electrode 211 and the driving signal is applied to the second electrode 212, the detection unit 140 detects a moving amount of the electric charge corresponding to the electrostatic capacitance in the first electrode 211 as the sensing electrode as a detection value Vs1d2 and stores the detection value in the memory 151.

Next, in step 212(S212), the determination section 152 calculates a difference D1 ═ Vs1D2 to Vs1D1 from the detection value Vs1D1 and the detection value Vs1D2 stored in the memory 151.

Next, in step 214(S214), the driving sensing selection part 230 is connected crosswise as shown in fig. 11, that is, the first electrode 211 is connected to the driving signal control part 160, and the second electrode 212 is connected to the sensing signal generation part 130. Thus, the first electrode 211 serves as a driving electrode, and the second electrode 212 serves as a sensing electrode.

Next, in step 216(S216), in a state where the sense signal generated in the sense signal generation section 130 is applied to the second electrode 212 serving as the sense electrode, the drive signal control section 160 also applies the sense signal to the first electrode 211 serving as the drive electrode. Specifically, in a state where the sensing signal generated in the sensing signal generating part 130 is applied to the second electrode 212, the switch 162 within the driving signal control part 160 connects the sensing signal generating part 130 with the first electrode 211, thereby applying the sensing signal to the first electrode 211.

Next, in step 218(S218), in a state where the sensing signal is applied to the first electrode 211 and the second electrode 212, the detection unit 140 detects a movement amount of the electric charge corresponding to the electrostatic capacitance in the second electrode 212 as the sensing electrode as a detection value Vs2d1, and stores the detection value in the memory 151.

Next, in step 220(S220), in a state where the sensing signal generated in the sensing signal generating section 130 is applied to the second electrode 212 which becomes the sensing electrode, the driving signal control section 160 applies the driving signal generated in the driving signal generating section 161 to the first electrode 211 which becomes the driving electrode. Specifically, in a state where the sense signal generated in the sense signal generating section 130 is applied to the second electrode 212, the switch 162 in the drive signal control section 160 connects the drive signal generating section 161 to the first electrode 211, and applies the drive signal to the first electrode 211.

Next, in step 222(S222), in a state where the sensing signal is applied to the second electrode 212 and the drive signal is applied to the first electrode 211, the detection unit 140 detects a movement amount of the electric charge corresponding to the electrostatic capacitance in the second electrode 212 as the sensing electrode as a detection value Vs2d2 and stores the detection value in the memory 151.

Next, in step 224(S224), the determination section 152 calculates the difference D2 — Vs2D2-Vs2D1 from the detection value Vs2D1 and the detection value Vs2D2 stored in the memory 151.

Next, in step 226(S226), the determination unit 152 determines whether or not the value of the difference D1 is greater than a predetermined first threshold value Th 1. If the value of the difference D1 is greater than the given first threshold value Th1, the routine proceeds to step 228, and if the value of the difference D1 is equal to or less than the given first threshold value Th1, the routine proceeds to step 232.

Next, in step 228(S228), the determination unit 152 determines whether or not the value of the difference D2 is greater than a predetermined first threshold value Th 1. If the value of the difference D2 is greater than the given first threshold value Th1, the routine proceeds to step 230, and if the value of the difference D2 is equal to or less than the given first threshold value Th1, the routine proceeds to step 232.

Next, in step 230(S230), the determination unit 152 determines whether or not the values of D2-D1 are equal to or less than a predetermined second threshold value Th 2. In the case where the values of D2-D1 are equal to or lower than the given second threshold value Th2, the process proceeds to step 234, and in the case where the values of D2-D1 are greater than the given second threshold value Th2, the process proceeds to step 232.

In step 232(S232), the determination unit 152 determines that the portion of the sensor unit 210 where the first electrode 211 and the second electrode 212 are provided is not held, outputs information that is not held, and ends the process. In step 234(S234), determination unit 152 determines that the detection target approaches both first electrode 211 and second electrode 212. That is, the determination unit 152 determines that the portion of the sensor unit 210 where the first electrode 211 and the second electrode 212 are provided is held, and outputs the information being held, and ends the process.

In the capacitance detection sensor according to the present embodiment, the first electrode 211 and the second electrode 212 are replaced with the sense electrode and the drive electrode, whereby erroneous detection due to the influence of noise or the like can be suppressed. The value of the difference D1 and the value of the difference D2 are values proportional to the value on the right side of expression 3, and are basically the same even when the sense electrode and the drive electrode are replaced with each other. Although the value of the difference D1 or the value of the difference D2 may become a large value instantaneously due to the influence of noise or the like, the probability that both the value of the difference D1 and the value of the difference D2 become large values and the values are substantially the same is extremely low. Therefore, when the value of the difference D1 or the value of the difference D2 momentarily becomes large due to the influence of noise or the like, since the values of D2 to D1 are larger than the predetermined second threshold value Th2, the determination unit 152 does not determine that the portions of the sensor unit 210 where the first electrode 211 and the second electrode 212 are provided are not held, which is induced by the influence of noise or the like, and thus the detection accuracy can be improved.

Other than the above, the same as the first embodiment is applied.

[ third embodiment ]

Next, a third embodiment will be explained. The present embodiment is a steering wheel, a door handle, a smartphone, or the like, using the electrostatic capacity detection sensor of the first or second embodiment. As shown in fig. 13, the steering wheel 301 of the present embodiment has the first electrode 311 attached to the near side and the second electrode 312 attached to the far side, and for example, when the steering wheel 301 is held, it is detected that the thumb 381 and the index finger 382 of the human body are close to the first electrode 311 and the second electrode 312. This makes it possible to accurately determine the holding of the steering wheel 301.

In the capacitance detection sensor according to the first embodiment, one of the first electrode 311 and the second electrode 312 corresponds to the sensing electrode 111, and the other corresponds to the driving electrode 112. In the capacitance detection sensor according to the second embodiment, the first electrode 311 corresponds to the first electrode 211, and the second electrode 312 corresponds to the second electrode 212.

As shown in fig. 14, the door handle 302 of the present embodiment has the first electrode 311 attached to the near side and the second electrode 312 attached to the far side, and for example, when the door handle 302 is held, it is detected that the thumb 381 of the human body approaches the second electrode 312 by fingers other than the thumb 381, such as the first electrode 311, the index finger 382, and the middle finger 383. This makes it possible to accurately determine whether the door handle 302 is held.

In addition, in the smartphone 303 of the present embodiment, the electrodes 321, 322, 323, and 324 are attached near the left side surface, the electrodes 325, 326, 327, and 328 are attached near the right side surface, the sensing electrode and the driving electrode are selected from among the electrodes 321, 322, 323, 324, 325, 326, 327, and 328, and it is detected that any one of the thumb 381, the index finger 382, the middle finger 383, the ring finger 384, and the little finger 385 of the human body approaches both of the two selected electrodes. This makes it possible to accurately determine whether the smartphone 303 is held.

Although the embodiments have been described in detail, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the claims.

The international application claims priority of japanese patent application No. 2019-095930, which was filed on a year of 2019, 5, month of 22, and the entire contents of the application are incorporated into the international application.

-description of symbols-

80 human body

81 part(s)

82 another part

110 sensor part

111 sense electrode

112 drive electrode

120 circuit part

130 sense signal generating part

140 detection unit

150 holding determination unit

151 memory

152 determination unit

160 driving signal control part

161 drive signal generating section

162 switch

170 control unit.