Human body detection sensor system using signal phase shifting

Abstract

The human body detection sensor system includes a first electrode, a second electrode, a drive circuit, a detection circuit, and a comparison circuit. The second electrode is connected to the first electrode via a capacitance. The drive circuit is configured to generate a first signal, the first signal driving the first electrode with a defined frequency. The detection circuit is configured to detect a second signal, the second signal being generated at the second electrode in response to the first signal being provided to the first electrode. The comparison circuit is configured to compare the first signal with the second signal. The comparison circuit detects a touch and / or approach of an object having an impedance in a specific range corresponding to a human body with respect to at least one of the first electrode and the second electrode when a phase difference between the first signal and the second signal is within a defined range.

Description

[Technical field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Patent Application No. 17 / 455,728, filed November 19, 2021. The disclosures of the above U.S. patent applications are incorporated herein by reference in their entireties.

[0002] [Technical field] The present disclosure relates to capacitive sensors, and more particularly to a human body detecting sensor system that detects a touch and / or approach of a human body by using a phase difference between a drive signal and a sensed signal. [Background technology]

[0003] The discussion of the background art provided herein is intended to generally indicate the context of the disclosure. The inventors' work described herein is not expressly or impliedly admitted as prior art to the present disclosure, to the extent described in the Background section of the present disclosure, as well as aspects of the specification that may not qualify as prior art at the time of filing.

[0004] The capacitive sensor may be used to sense contact between an object (e.g., a finger) and a surface of the object, such as a surface of a steering wheel of a vehicle, and generate a signal indicative of the sensed contact. For example, a waveform generator may be configured to generate a signal and output the signal to the capacitive sensor. In some examples, as described in U.S. Pat. No. 9,827,996, a steering wheel sensor system includes a flexible piezoelectric substrate and an array of sensors wrapped around the steering wheel, and detects that a contact (grip) force associated with the array of sensors exceeds a threshold for a specified period of time. Thus, the presence or absence of an object touching the sensor may be determined based on the values ​​of the physical quantities from the sensors. Summary of the Invention

[0005] 1. Technical challenges Unfortunately, however, the capacitive sensor described above cannot quantify the capacitance Cfr between the human body and the sensor, but rather can quantify the series combined capacitance Cfr*Cfg / (Cfr+Cfg) of the coupling capacitance Cfg between the human body and ground and the capacitance Cfr between the human body and the sensor. Therefore, the capacitive sensor may not accurately distinguish between contact by other objects such as a liquid or a grounded metal and contact by the human body.

[0006] 2. Solutions to the issues The human body detecting sensor system includes a first electrode, a second electrode, a drive circuit, a detection circuit, and a comparison circuit. The second electrode is connected to the first electrode via a capacitance. The drive circuit is configured to generate a first signal, the first signal being provided to the first electrode with a prescribed frequency. The detection circuit is configured to detect a second signal, the second signal being generated at the second electrode in response to the first signal being provided to the first electrode. The comparison circuit is configured to compare the first signal with the second signal. Advantageously, the comparison circuit is configured to detect a touch and / or an approach of a human body with respect to at least one of the first and second electrodes when a phase difference and an amplitude difference between the first signal and the second signal is within a prescribed range.

[0007] Regarding other features, in the human body detection sensor system, the drive circuit is configured to select the predetermined frequency of the first signal from a plurality of frequencies.

[0008] Regarding other features, in the human body detection sensor system, a capacitor is tuned based on the selected predetermined frequency of the first signal.

[0009] Regarding another feature, in the human body detection sensor system, an impedance between the second electrode and a ground potential is adjusted based on a selected and defined frequency of the first signal.

[0010] Regarding another feature, in the human body detection sensor system, the first electrode is arranged in a steering wheel.

[0011] Regarding another feature, in the human body detection sensor system, the first electrode and / or the second electrode are disposed in a steering wheel.

[0012] Regarding other features, in the human body detection sensor system, the specified frequency of the first signal is in a range of 1 [MHz] to 100 [MHz].

[0013] Regarding other features, in the human body detection sensor system, the comparison circuit is configured to detect the touch and / or the approach of an object, which has an impedance in a certain range corresponding to a human body, with respect to the second electrode, when the phase difference between the first signal and the second signal is within the prescribed range.

[0014] Regarding other features, in the human body detection sensor system, the comparison circuit is configured to detect the touch and / or the approach of an object, which has an impedance corresponding to a human body, with respect to the second electrode when an amplitude difference between the first signal and the second signal is within another prescribed range.

[0015] Regarding other features, in the human body detection sensor system, the specified range of the phase difference is in a range of 1 degree to 42 degrees as a phase shift, and more specifically, in a range of 26 degrees to 42 degrees as a phase shift. These ranges are determined by the composite impedance Z all (a combined impedance Z all ) is defined experimentally using the phase components Φ and Φ'.

[0016] Regarding another feature, in the human body detection sensor system, a size of the second electrode and a thickness of an overlay of the second electrode are set such that a capacitance between the human body and the second electrode becomes the same as a capacitive component of the human body when a surface touched by the human body with respect to the overlay of the second electrode is detected.

[0017] Further scope of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0018] The present disclosure will become more fully understood from the detailed description of the invention and the accompanying drawings, in which:

[0019] [Figure 1] An exemplary human body detection system including a capacitive sensor with two electrodes and a controller. [Diagram 2] FIG. 2 is an exemplary schematic circuit diagram of a capacitive sensor of a human body detection system including human body impedance; [Figure 3A] 2 is an example graph illustrating impedance (phase) changes between a drive signal and a sensed signal of the capacitive sensor shown in FIG. 1. [Figure 3B] 2 is an exemplary graph illustrating the change in impedance (phase) between the drive and sense signals of the capacitive sensor shown in FIG. 1. [Figure 4] 1 is an exemplary human body detection system including a capacitive sensor with one electrode and a controller. [Figure 5A] 5 is an exemplary graph illustrating the change in impedance (phase) between the drive and sense signals of the capacitive sensor shown in FIG. 4. [Figure 5B] 5 is an exemplary graph illustrating the change in impedance (phase) between the drive and sense signals of the capacitive sensor shown in FIG. 4. [Figure 6] 5 is an example sensor circuit including some components of the sensor module and controller shown in FIG. 1, FIG. 2, and / or FIG. 4. [Figure 7] FIG. 1 is an exemplary schematic diagram of a steering wheel having multiple electrodes.

[0020] In the various drawings, reference numbers may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] A capacitive touch sensor detects the change in capacitance between a transmitter and receiver in a "mutual capacitance" type sensor, or the loading of a single electrode receiver in a "self-capacitance" type sensor. When a floating or small surface area conductor is brought close to a mutual capacitance sensor, the sensed capacitance Ctr increases. When the same conductive object is grounded or its surface area is significantly increased, the sensed capacitance Ctr decreases. Very similar behavior is observed using high dielectric, non-conductive objects. When a conductive or high dielectric object comes in close proximity to a self-capacitance sensor electrode and ground, the sensed capacitance decreases. When a small object floats electrically near the sense electrode, no change in capacitance is detected. The human body typically has a capacitance of 100 to 200 pF from the conductive skin surface area. Many touch sensors see this as enough capacitance to look like a mostly grounded conductive object.Most capacitance touch sensors flag a "touch" when the change in capacitance exceeds some nominal threshold.

[0022] The change in the signal provided to the capacitive sensor in response to contact with an object (corresponding to the sensed signal) is usually small compared to the provided signal (i.e., control, excitation, or drive signal), and it may be difficult to distinguish between a touch by a non-human object, such as a touch by an aqueous liquid (conductive or non-conductive) close to ground, and a touch by a human body, such as a touch by a finger or hand. A similar behavior can be encountered in the case of a grounded conductor (such as a metal conductor such as aluminum foil). For example, when a non-human object touches a capacitive sensor and the capacitive sensor generates a sensed signal corresponding to the physical quantity of the touch, the capacitive sensor may erroneously determine that the detected physical quantity is the result of a touch by a human body.

[0023] In some of the examples, a self-capacitance sensor can quantify the capacitance between a sensor element and a detection target. A self-capacitance sensor actually quantifies the combined capacitance between the detection target, the sensor element, and ground potential. Specifically, when a human body approaches a sensor element, the sensor element does not quantify the capacitance Cfr between the human body and the sensor element, but rather quantifies the series combined capacitance (Cfr×Cfg / (Cfr+Cfg)) of the capacitance Cfr (between the human body and the sensor element) and the capacitance Cfg between the human body and ground potential. In this way, the sensor element may not correctly detect whether the object is a human body or a water bottle (liquid or floating conductor) because the water bottle (liquid or floating conductor) may have a capacitance Cwg between the water bottle (liquid or floating conductor) and ground potential that is similar to the capacitance Cfg between a human body and ground potential. In addition, because a grounded conductor (metal) is grounded, the sensor element may not correctly detect whether the object is a human body or a grounded conductor (metal). Specifically, depending on the size of the electrodes and the distance to a touch, and depending on how "grounded" a human body is, the capacitance of the sensor element may change in a manner similar to that of a grounded conductor (metal). The range of capacitance change from the human body compared to a grounded conductor (metal) can be significantly larger depending on the "groundedness" of the body, the area of ​​the touch, a distance from the touch, sweat, etc.The electrodes of the sensor element are usually insulated so that galvanic connections to the sensed object are not possible, although capacitive connections are possible.

[0024] Referring now to FIG. 1, an exemplary human body detection system 100 is shown, which includes a sensor module 110 corresponding to a capacitive sensor, and a sensor controller 120 (including a CPU and memory as discussed below). The sensor module 110 includes a first electrode Tx and a second electrode Rx. The first electrode Tx and the second electrode Rx are usually close to each other to form a capacitor Crt. However, if additional signals are required, separate capacitors may be added in parallel with the first electrode Tx and the second electrode Rx. The sensor controller 120 includes a CPU (processor), memories such as RAM, ROM, and EEPROM, DACs, ADCs, amplifiers, and filters, and controls a drive circuit 130, a detection circuit 140, a determination circuit 150, and a phase comparison circuit 160 by executing programs or commands stored in the memory by the processor. The detection circuit 140 includes a phase comparison circuit 160 .

[0025] In some of the examples, the second electrode Rx may be disposed within, wrapped around, or covering a core material of the vehicle steering wheel 111. The second electrode Rx is used to detect the approach (i.e., being within a proximity of) and / or contact (touch) of the steering wheel 111 by a human body 112 (e.g., a finger or hand). Similarly, the first electrode Tx may be disposed within, wrapped around, or covering a core material of the steering wheel 111, as shown in FIG. 1. The first electrode Tx is used to detect the approach (i.e., being within a proximity of) and / or contact (touch) of the steering wheel 111 by a human body 112 (e.g., a finger or hand). In some of the examples, the first electrode Tx and the second electrode Rx may be wrapped around the entire steering wheel 111 or may cover the entire steering wheel 111. On the other hand, since the first electrode Tx does not need to be touched by the human body 112, the first electrode Tx may be disposed on a structure other than the steering wheel 111 as shown in FIG. 4. Specifically, as described later, the phase comparison circuit 160 needs to receive the drive signal Vin from the drive circuit 130 as a reference signal, and needs to receive the detection signal Vout from the second electrode Rx as a detection result signal. In this way, at least the second electrode Rx needs to be disposed at a position (e.g., the steering wheel 112, etc.) where the human body approaches or touches.

[0026] The driving circuit 130 provides a drive signal or excitation signal Vin (e.g., a sine wave) to the first electrode Tx of the sensor module 110 and to a phase comparison circuit 160 in the detection circuit 140. The drive signal Vin has a specified frequency, such as 8 MHz or 10 MHz, which may be selected from a plurality of frequencies, such as from a range of 1 MHz to 100 MHz. In response to applying the drive signal Vin to the first electrode Tx, a sense signal Vout (e.g., a sine wave) is generated by the second electrode Rx. The sense signal Vout has a frequency corresponding to the capacitor Crt and the specified frequency of the drive signal Vin. In this way, depending on the capacitance of the capacitor Crt, the phase and amplitude of the waveform of the sense signal Vout may be substantially the same as the phase and amplitude of the drive signal Vin. The sense signal Vout is provided to the phase comparison circuit 160 in the detection circuit 140. Additionally, the sensor module 110 has an impedance hanging from the second electrode Rx, such as that represented by a capacitor Crx and a resistor Rrx shown in FIG. 1.

[0027] When a part of the human body 112 approaches (i.e., becomes within a proximity of) the second electrode Rx and the first electrode Tx in the steering wheel 111 and / or touches (touches) the second electrode Rx and the first electrode Tx in the steering wheel 111, the detection signal Vout changes. Specifically, the phase of the waveform of the detection signal Vout is shifted or delayed for a certain degree compared to the phase of the waveform of the detection signal Vout when there is no object approaching and / or touching the second electrode Rx and the first electrode Tx in the steering wheel 111. In other words, the phase of the waveform of the detection signal Vout is shifted or delayed for a certain degree compared to the phase of the waveform of the drive signal Vin. These phase differences (shifts or delays) occur due to the resistance capacitance (RC) mix of the impedance of the human body. The amplitude of the sense signal Vout also varies within an acceptable range upon proximity or touch by the human body 112 .

[0028] After the phase comparison circuit 160 receives both the driving signal Vin and the sense signal Vout, the phase comparison circuit 160 compares the two signals Vin and Vout, and quantifies the difference between the two signals Vin and Vout. Specifically, the phase comparison circuit 160 compares the phase and amplitude of the two signals Vin and Vout. When the quantified difference between the phase and amplitude of the two signals Vin and Vout is within a prescribed range, the decision circuit 150 determines that the human body 112 is approaching and / or touching the steering wheel 111. In particular, as will be discussed in detail below, the decision circuit 150 determines that the human body 112 is approaching and / or touching the steering wheel 111 when the quantified difference (angle (degree) difference) in phase between those two signals Vin and Vout falls within a specified range, for example, between 1° and 42°, more specifically, between 26° and 42°. The phase difference of 26° and 42° represents a composite impedance Z all Φ′ are approximately 41.7° (41.7°−0°=41.7°) and 26.2° (40.9°−14.7°=26.2°), corresponding to the experiments discussed below.

[0029] Conversely, as will be discussed in detail below, when a non-human object such as liquid (floating conductor) or metal (grounded conductor) approaches and / or touches the steering wheel 111, the quantified difference in phase between the two signals Vin and Vout is outside a prescribed range, or there is no substantial phase difference between the two signals Vin and Vout. Specifically, when a grounded conductor, a floating conductor, a grounded dielectric, or a floating dielectric comes in proximity to the sensor element in the steering wheel 111, no phase shift is observed in the sense signal Vout. Meanwhile, as mentioned above, when the human body 112 comes in proximity to the sensor element, a phase shift is observed because the human body also has a certain amount of electrical resistance. A combination of resistance and capacitance in the sensor module 110 causes a phase shift in the sense signal Vout. Therefore, the decision circuit 160 can accurately and reliably detect the approach and / or touch of the steering wheel 111 by the human body 112, and can distinguish between the approach and / or touch of the steering wheel 111 by a non-human object and the approach and / or touch by the human body 112, thereby improving the safety of the vehicle.

[0030] Although a single pair of first electrodes Tx and second electrodes Rx has been described in the above examples, multiple first electrodes Tx and / or multiple second electrodes Rx may be arranged in the steering wheel 111. For example, as shown in FIG. 7, the steering wheel 111 may have multiple spaced apart electrodes 710 and a circular electrode 720. The circular electrode 720 corresponds to the first electrodes Tx, and the multiple electrodes 710 correspond to the multiple second electrodes Rx. In this manner, the sensor module 110 shown in FIG. 1 and FIG. 2 and the sensor module 210 shown in FIG. 4 (described later) may include multiple electrodes 710 and a circular electrode 720, respectively. This configuration allows the cost and complexity of the sensor modules 110 and 210 to be reduced.

[0031] In FIG. 7, thirteen electrodes 710 are illustrated. However, the number of electrodes 710 may be less than thirteen or more than thirteen, as necessary. Furthermore, although the circular electrode 720 is provided on the inner circumference of the steering wheel 111 in FIG. 7, the circular electrode 720 may be omitted when the sensor modules 110 and 210 are appropriately configured. Specifically, when the circular electrode 720 is omitted from the steering wheel 111, each of the plurality of electrodes 710 corresponds to a single pair of a first electrode Tx and a second electrode Rx. In this case, each of the plurality of electrodes 710 corresponds to a single sensor module 110 or 210. The advantage of this configuration is to reduce the capacitance to ground (Crg) and therefore increase the signal-to-noise ratio of the system 100 or 200. In an alternative configuration, the number of electrodes 710 is reduced to four and the circular electrode 720 is omitted. The four electrodes 710 are placed in areas of the steering wheel 111 that are known to be frequently touched by the driver's hands, generating four drive signals Vin and four sense signals Vout in this case. In this way, there are 16 unique pairs of signal combinations, resulting in 16 unique touch areas of the sensor modules 110 and 210 on the steering wheel 111.

[0032] In contrast, as described above, when the circular electrode 720 is provided, the circular electrode 720 corresponds to a single second electrode Rx, and the multiple electrodes 710 correspond to multiple first electrodes Tx. Since the multiple first electrodes Tx are arranged at several different places in the steering wheel 111, the sensor controller 120 can select which first electrode Tx to supply the drive signal Vin from the drive circuit 130 to. In this example, when the detection circuit 140 does not detect a phase difference at a first specific position of the steering wheel 111 where the selected first electrode Tx (Tx1) receives the drive signal Vin, the human body detection system 100 may determine that the human body 112 is not approaching and / or touching the first specific position of the steering wheel 111. Also, since the detection circuit 140 can detect the second specific position of the steering wheel 111 where a phase difference (shift or delay) occurs in response to the supply of the drive signal Vin to the selected first electrode Tx (Tx2) at the second specific position of the steering wheel 111, the human body detection system 100 can determine the exact position (second specific position) where the human body 112 approaches and / or touches the steering wheel 111 in the vicinity of the selected first electrode Tx (Tx2) and second electrode Rx. In addition, as described above, by using multiple small sensors arranged around the steering wheel 111, it is possible to achieve miniaturization of sensors for the human body detection sensor system 100.

[0033] Referring to FIG. 2, FIG. 2 partially corresponds to the diagram shown in FIG. 1 and provides an exemplary schematic circuit diagram of the sensor module 110 of the human body detection system 100 including the impedance (represented by Cf and Rf) of the human body 112 (e.g., finger or hand). A capacitor Crt is provided between the first electrode Tx and the second electrode Rx. A capacitor Crx and a resistor Rrx are provided as an impedance hanging from the second electrode Rx. When the human body 112 approaches the first electrode Tx and the second electrode Rx, a capacitance Cft and a capacitance Cfr are generated between the human body 112 (e.g., finger or hand) and the first electrode Tx and the second electrode Rx, respectively. The human body 112 (e.g., finger or hand) has an impedance (represented by capacitor Cf and resistor Rf).

[0034] The defined frequency supplied to the first electrode Tx is determined by the various capacitors and resistors described above (composite impedance Z all ) changes at the second electrode Rx, thereby changing or shifting (delaying) the phase and impedance of the sense signal Vout. Such changes in phase and amplitude result in a composite impedance Z between the first electrode Tx and the second electrode Rx. all This is caused by the composite impedance Z all The phase component of corresponds to the angle between the real and imaginary components. Thus, the composite impedance Z all The phase component of varies due to a change in a particular capacitance or resistance value.

[0035] For example, when the detection target is not located near the second electrode Rx and the first electrode Tx, the composite impedance Z allOn the other hand, when the detection object is located near the second electrode Rx and the first electrode Tx (when the detection object approaches and / or contacts the second electrode Rx and the first electrode Tx), the combined impedance Z allThe phase component of is Φ'. Each of Φ and Φ' is equal to the difference between the phase of the driving signal Vin and the phase of the sense signal Vout. Since the phase of the driving signal Vin is the reference phase, Φ is 0° (the detection target is not located in the vicinity of the second electrode Rx and the first electrode Tx). In this way, when Φ' is 1° or more, it is determined that the human body approaches and / or touches the second electrode Rx and the first electrode Tx. As mentioned above, it should be noted that when a grounded conductor, a floating conductor, a grounded dielectric, or a floating dielectric comes in proximity to the sensor element in the steering wheel 111, no phase shift is observed in the sense signal Vout. On the other hand, when the human body 112 comes in proximity to the sensor element, a phase shift is observed because the human body also has a certain amount of electrical resistance. Furthermore, when the human body is located near the second electrode Rx and the first electrode Tx, Φ' is a substantial angle, such as in the range of 1° to 42°, more specifically, in the range of 26° to 42°. As described above, since the phase comparison circuit 160 is used to receive the detection signal Vout from the second electrode Rx, it should be noted that in order to detect such approach and / or contact (touch), it is sufficient that the detection object can at least approach and / or touch the second electrode Rx. Thus, in this application, the expression "the human body 112 (or other object) approaches and / or touches the second electrode Rx and the first electrode Tx" also means "a part (such as a finger or hand) of the human body 112 (or other object) approaches and / or touches at least the second electrode Rx". The example sensor module 110 may be configured to calculate a composite impedance Z by setting the defined frequency of the drive signal Vin and the parameters and / or values ​​of the internal impedances (such as Crt and Zrx (Crx and Rrx)). allSince the phase component Φ of the human body 112 has a large difference between the phase components Φ and Φ', the approach and / or touch by the human body 112 or an equivalent object having the same impedance as the human body 112 only causes a substantial change in the phase component. It should be noted that the human body 112 typically has a capacitance (e.g., Cf) of 100 pF and a resistance (e.g., Rf) of 510 Ω. In contrast, the approach and / or touch by a non-human object such as a liquid (floating conductor) or a grounded conductor (metal) does not cause a significant change in the phase component.

[0036] In some of the examples, referring to FIG. 2 , when the frequency of the drive signal Vin in the exemplary sensor module 110 is adjusted to 10 [MHz], the capacitance of the capacitor Crt (between the first electrode Tx and the second electrode Rx) is adjusted to 10 [pF], each of the capacitances Cft and Cfr is adjusted to 0 [pF], and the impedance Zrx hanging from the second electrode Rx is adjusted so that the capacitance of the capacitor Crx is 10 [pF] and the resistance value of the resistor Rrx is 1 [Ω], the combined impedance Zrx hanging from the second electrode Rx is calculated as follows: all is 0.500+(1.57×10 -5 )i. This composite impedance Z all corresponds substantially to 0 degrees (0°) as the phase component Φ.

[0037] On the other hand, as an experimental model of a human body (for the human body 112 (e.g., a finger or a hand)), impedance Z fingerWhen an experimental object (detection target) having an exemplary impedance (such as 100 μm) approaches the second electrode Rx and the first electrode Tx (of the sensor module 110 with various capacitances and resistances adjusted as described above) at a certain distance where each of the capacitances Cft and Cfr is 10 [pF], the composite impedance Z all This composite impedance Z (when approached by an experimental model of the human body) all corresponds to a phase component Φ' of approximately 41.7 degrees (41.7°). Since the phase difference is more than 40°, this phase difference (shift or delay) of the phase component (41.7°) is considered to be quite large. For the above experimental purposes, the impedance Z finger and the capacitances Cft and Cfr of the experimental object (either 0 [pF] or 10 [pF]), and the impedance Z hanging from the second electrode Rx is set as rx and the capacitance of the capacitor Crt are set as an example, so the combined impedance Z all The phase difference (shift or delay) between the phase component Φ and the phase component Φ' corresponds to the phase difference (shift or delay) between the drive signal Vin and the sense signal Vout.

[0038] Conversely, when a liquid (a floating conductor) (with Cf=100 pF and Rf=10 Ω) approaches and / or touches the second electrode Rx and the first electrode Tx (of the sensor module 110 with various capacitances and resistances adjusted as described above), the combined impedance Z all This composite impedance Z (upon approach and / or contact with the liquid) changes to 0.164+0.00455i. all corresponds to 0 degrees (0°) as the phase component Φ'. Thus, 0 degrees corresponds to the composite impedance Z all Since Φ is the same as the phase component Φ of Φ, there is no phase difference (shift or delay).

[0039] As explained above, the composite impedance Z between the first electrode Tx and the second electrode Rx all The phase difference threshold of the phase component Φ′ of is preferably set to be forty degrees (40°). When the phase difference (shift or delay) between the phase component Φ and the phase component Φ′ is equal to or greater than 40°, more specifically, the phase difference is within a range of 40° to 359°, the decision circuit 150 is configured to determine whether the human body 112 approaches and / or touches the second electrode Rx and the first electrode Tx (of the sensor module 110). When the phase difference is 360°, it may not be possible to determine whether 360° means that there is no phase difference or that there is a difference of one (or more) cycles of the sense signal Vout. Thus, the upper limit of the range is preferably not 360°. Thus, when the prescribed range is set as a phase difference (shift or delay) between the phase components Φ and Φ′ that is equal to or greater than 40°, more specifically within the range of 40° to 359°, and the sensor module 110 and the sensor controller 120 include preselected parameters such as the sensor size, the physical distance (capacitance) between the first electrode Tx and the second electrode Rx, the impedance Zrx hanging from the second electrode Rx, and the prescribed frequency of the drive signal Vin, as described above, the approach and / or touch of the human body 112 to the second electrode Rx and the first electrode Tx is determined as a combined impedance Zrx. all Based on the phase difference (shift or delay) between the phase components Φ and Φ', i.e., the phase difference (shift or delay) between the drive signal Vin and the sense signal Vout, it is possible to clearly distinguish the approach and contact of a non-human object such as a liquid (a floating conductor) or a grounded conductor (metal).

[0040] The capacitances Cf and Cfr are substantially in series. In this way, the series combined capacitance of Cf and Cfr is expressed by "Cf×Cfr / (Cf+Cfr)". The combined capacitance of Cf and Cfr seen from the second electrode Rx depends largely on the smaller capacitance of the capacitances of Cfr and Cf. In this way, when the difference between the capacitances of Cf and Cfr is large and the detection target approaches and / or touches the second electrode Rx of the sensor module 110, the phase of the detection signal Vout may change significantly even if the detection target has not yet touched it, or the phase may change even when a detection target other than the human body 112 with a small capacitance approaches. Therefore, it is preferable that the capacitances of Cf and Cfr are approximately the same value. For example, if the human body 112 has a capacitance of the capacitor Cf (100 pF or more), the capacitance Cfr should also be 100 pF at the time of approach and / or contact (touch) with the second electrode Rx.

[0041] Generally, there are many ways to detect the phase shift of a signal having a certain frequency, but the sensor module 110 has a detection resolution of the phase shift of about one degree (1°). Meanwhile, the detection resolution may be designed according to the closeness of the human body 112 (e.g., finger or hand) to the sensor module 110 (i.e., the steering wheel 111 having a first electrode Tx and a second electrode Rx). Of course, the thickness of the rubber, leather, or other material on the steering wheel 111 and the thickness of the driving groove may also be taken into consideration. In some of the examples, the sensor module 110 (and the sensor controller 120) may detect the phase difference (shift) using a PLL (phase-locked loop) circuit (a combination of a VCO (voltage controlled oscillator) and a phase detector). The output of the PLL is provided to a frequency counter (or an input capture counter) in the microcontroller. Some of the examples of the circuit options of the sensor module 110 are described later.

[0042] The PLL baseline frequency is preferably adjusted to approximately 8 MHz using an RC (resistor-capacitor) circuit; i.e., the preferred frequency is between 7 MHz and 10 MHz. When the human body 112 (e.g., a finger or hand) comes close to the first electrode Tx and the second electrode Rx, the frequency changes by a few thousand Hertz. A nonhuman target will not change the frequency of the PLL. It is preferable to have an active 4 pole band pass or low pass filter directly from the second electrode Rx before returning to the PLL. This configuration significantly reduces any noise, harmonics, or distortion that may creep into the sensed signal Vout from the second electrode Rx.

[0043] 3A and 3B, which provide exemplary graphs illustrating the impedance (phase) change (shift or delay) between the driving signal Vin and the sensed signal Vout of the sensor module 110 described above. Specifically, FIG. 3A illustrates a phase change or shift from a state in which the empirical model of the human body (human body 112) has not yet approached and / or touched the steering wheel 111 having the first electrode Tx and the second electrode Rx (corresponding to "X" (Z (No Touch)) and the phase is 0°) to a state in which the empirical model of the human body (human body 112) approaches and / or touches the steering wheel 111 having the first electrode Tx and the second electrode Rx (corresponding to the largest dot (Z (Touch)) and the phase is about 41.7°). The phase change or phase shift when the experimental model of the human body (human body 112) approaches and / or touches is shown using smaller dots (Z(No touch→Touch)) representing an increase in capacitance Cfr and capacitance Cft. Then, each of capacitances Cfr and Cft reaches 10 pF with a phase shift of 41.7° as shown by the largest dots.

[0044] In contrast, FIG. 3B shows a phase change or shift from when the liquid is not yet approaching and / or touching the steering wheel 111 having the first electrode Tx and the second electrode Rx (corresponding to “X” (Z (No Touch) and phase is 0°)) to when the liquid (floating conductor) approaches and / or touches the steering wheel 111 having the first electrode Tx and the second electrode Rx (corresponding to the largest dot (Z (Touch)) and phase is 0°). As the liquid approaches, the real part component or absolute value changes (smaller dot (Z (No touch) → Touch)), but the angle (phase shift) does not change substantially. The sensor module 110 outputs the sensed signal Vout (i.e., the composite impedance Z allSince the impedance of the human body 112 is reduced, the impedance of the human body 112 can be reduced by a large amount.

[0045] Referring now to FIG. 4, FIG. 4 illustrates another exemplary human body detection system 200. The system 200 includes an exemplary sensor module 210 having a second electrode Rx and a sensor controller 220. The sensor module 210 includes a first electrode Tx and a second electrode Rx. The second electrode Rx is disposed in, wrapped around, or wrapped on the core of a steering wheel 211 of a vehicle. In some of the examples, the second electrode Rx may be disposed around the entire steering wheel 211 or may cover the entire steering wheel 211. In contrast, the first electrode Tx is not disposed in the steering wheel 211, but rather is disposed elsewhere, such as in another component.

[0046] In some of the examples, the first electrode Tx may be located under a thick surface material such as rubber or may be located on a spoke (or hub or shaft) of the steering wheel 211. In some of the examples, the first electrode Tx may simply be a node in a circuit or a trace on a circuit board. In this way, the first electrode Tx may not be exposed at the steering wheel 211. The first electrode Tx and the second electrode Rx are connected through a capacitor Crt, which may be a separate capacitor or a capacitor formed by the proximity of the first electrode Tx to the second electrode Rx. The sensor controller 220 includes a CPU (processor), memories such as RAM, ROM, and EEPROM, DAC, ADC, amplifiers, filters, etc., and controls the driving circuit 230, the detection circuit 240, the decision circuit 250, and the phase comparison circuit 260 by executing a program or command stored in the memory by the processor. The detection circuit 240 includes the phase comparison circuit 260. The second electrode Rx detects the approach (i.e., being within a proximity of) and / or contact (touch) of the human body 212 (such as a finger or hand) to the steering wheel 211 (as a phase difference between two signals Vin and Vout).

[0047] The driving circuit 230 provides a driving or excitation signal Vin (e.g., a sine wave) to the first electrode Tx of the sensor module 210 and to a phase comparison circuit 260 in the detection circuit 240. The driving signal Vin has a specified frequency, such as 8 MHz or 10 MHz, which may be selected from a number of frequencies, such as from a range of 1 MHz to 100 MHz. A sensing signal Vout (e.g., a sine wave) is generated by the second electrode Rx in response to the application of the driving signal Vin to the first electrode Tx. The sensing signal Vout has a frequency corresponding to the specified frequency of the driving signal Vin and the capacitor Crt. In this way, depending on the capacitance of the capacitor Crt, the phase and amplitude of the waveform of the sensing signal Vout may be substantially the same as the phase and amplitude of the driving signal Vin. The sensing signal Vout is provided to the phase comparison circuit 260 in the detection circuit 240. Additionally, the sensor module 210 shown in Figure 4 has an impedance hanging from the second electrode Rx, such as the impedance represented by the capacitor Crx and resistor Rrx shown in Figure 4. The capacitance Cfr shown in Figure 2 has been omitted from Figure 4 for ease of illustration.

[0048] When the human body 212 approaches (i.e., becomes within a proximity of) and / or touches the second electrode Rx in the steering wheel 211, the detection signal Vout changes. Specifically, the phase of the waveform of the detection signal Vout is shifted or delayed for a certain degree compared to the phase of the waveform of the detection signal Vout when there is no object approaching and / or touching the second electrode Rx in the steering wheel 211. In other words, the phase of the waveform of the detection signal Vout is shifted or delayed for a certain degree compared to the phase of the waveform of the drive signal Vin. These phase differences (shifts or delays) occur due to the resistance capacitance (RC) mix of the impedance of the human body. The amplitude of the sense signal Vout also varies within an acceptable range upon proximity or touch by the human body 112 .

[0049] After the phase comparison circuit 260 receives both the driving signal Vin and the sense signal Vout, the phase comparison circuit 260 compares the two signals Vin and Vout, and quantifies the difference between the two signals Vin and Vout. Specifically, the phase comparison circuit 260 compares the phase and amplitude of the two signals Vin and Vout. When the quantified difference in the phase and amplitude of the two signals Vin and Vout is within a prescribed range, the decision circuit 250 determines that the human body 212 is approaching and / or touching (or is approaching and / or touching) the steering wheel 211. In particular, as will be discussed in detail below, the decision circuit 250 determines that the human body 212 is approaching and / or touching the steering wheel 211 when a quantified difference (angle (degree) difference) in phase between those two signals Vin and Vout falls within a specified range, such as greater than or equal to 1° and less than or equal to 42°, more particularly, greater than or equal to 26° and less than or equal to 42°.

[0050] On the contrary, as will be discussed in detail below, when a non-human object, such as a liquid (e.g., a floating conductor) or a metal (e.g., a grounded conductor), approaches and / or touches the steering wheel 211, the quantified difference in phase between the two signals Vin and Vout is outside a prescribed range, or there is no substantial phase difference between the two signals Vin and Vout. Thus, the decision circuit 260 can accurately and reliably detect the approach and / or touch of the steering wheel 211 by the human body 212, and can distinguish between the approach and / or touch of the steering wheel 211 by a non-human object and the approach and / or touch of the human body 112. As a result, the safety of the vehicle is improved.

[0051] Although a single pair of the first electrode Tx and the second electrode Rx has been described in the above examples, multiple second electrodes Rx may be disposed in the steering wheel 211. For example, as discussed above, FIG. 7 shows a steering wheel 111 having multiple electrodes 710 and a circular electrode 720. The circular electrode 720 corresponds to the first electrode Tx, and the multiple electrodes 710 correspond to the multiple second electrodes Rx. If desired, the circular electrode 720 may be omitted from the steering wheel 111. In this case, each of the multiple electrodes 710 corresponds to a single pair of the first electrode Tx and the second electrode Rx. As a result, each of the multiple electrodes 710 corresponds to a single sensor module 110 or 210.

[0052] When the multiple second electrodes Rx are arranged at several different places in the steering wheel 211, the sensor controller 220 can determine which of the sense signals Vout from the various second electrodes to change (shift or delay). In this example, when the detection circuit 240 does not detect a phase difference of the sense signals Vout from the selected second electrode Rx (Rx1) arranged at the first specific position of the steering wheel 211, the human body detection system 200 may determine that the human body 112 has not yet approached and / or touched the first specific position of the steering wheel 211. Also, since the detection circuit 240 can detect the second specific position of the steering wheel 211 where the phase difference (shift or delay) occurs in response to receiving and comparing the detection signal Vout from the selected second electrode Rx (Rx2) at the second specific position of the steering wheel 211, the human body detection system 200 can determine the exact position (second specific position) where the human body 212 approaches and / or touches the steering wheel 211 near the selected second electrode Rx (Rx2). In addition, by using multiple small sensors arranged around the steering wheel 211 as shown in FIG. 7, it is possible to achieve miniaturization of the sensor for the human body detection sensor system 200.

[0053] The configuration shown in FIG. 4 also provides a synthetic impedance Z similar to that described with respect to FIG. all However, it does not include the capacitance Cft. In contrast, the composite impedance Z all The redundant description will be omitted in this specification.

[0054] When the detection target is not located near the second electrode Rx, the composite impedance Z allThe phase component of is Φ. On the other hand, when the detection object is located near the second electrode Rx (when the detection object approaches and / or contacts the second electrode Rx), the composite impedance Z all The phase component of is Φ'. The sensor module 210 sets the synthetic impedance Z by setting the specified frequency of the drive signal Vin and the parameters and / or values ​​of the internal impedances (such as Crt and Zrx (Crx and Rrx)). all Since the phase component Φ of the human body 212 has a large difference between the phase components Φ and Φ', the phase component is only substantially changed by proximity and / or touch with the human body 212 or an equivalent object having the same impedance as the human body 212. Conversely, the phase component is not significantly changed by proximity and / or touch with a non-human object such as a liquid (a floating conductor) or a grounded conductor (a metal).

[0055] In some of the examples, referring to FIG. 4, when the frequency of the drive signal Vin in the sensor module 210 is adjusted to 20 [MHz], the capacitance of the capacitor Crt (between the first electrode Tx and the second electrode Rx) is adjusted to 10 [pF], the capacitance Cfr is adjusted to 0 [pF], and the impedance Zrx (see FIG. 2) hanging from the second electrode Rx (shown in FIG. 2) is adjusted so that the capacitance of the capacitor Crx is 10 [pF] and the resistance value of the resistor Rrx is 500 [Ω], the synthetic impedance Z all The result is 0.545+0.1430i. This composite impedance Z all corresponds to a phase component Φ of approximately 14.7 degrees (14.7°).

[0056] On the other hand, as an experimental model of a human body (for a human body 112 (e.g., a finger or a hand)), an impedance Z (shown in FIG. 2 ) (Cf=100 pF and Rf=510 Ω) was used (as explained above). finger When an experimental object (detection target) having an exemplary impedance (such as 100 pF) approaches (and / or touches) the second electrode Rx (of the sensor module 210 with various capacitances and resistances adjusted as described above) at a certain distance where the capacitance Cfr is 100 pF, the composite impedance Z all This composite impedance Z (when approached by an experimental model of the human body) all corresponds to a phase component Φ' of approximately 40.9 degrees (40.9°). Since the phase difference is now more than 26°, this phase difference (shift or delay) of the phase component (26.2°) is considered to be quite large. For the purposes of the above experiment, the impedance Z finger and the capacitance Cfr of the experimental object (either 0 [pF] or 100 [pF]), and the impedance Z hanging from the second electrode Rx is set as rx and the capacitance of the capacitor Crt are set as an example, so the combined impedance Z all The phase difference (shift or delay) between the phase component Φ and the phase component Φ' corresponds to the phase difference (shift or delay) between the drive signal Vin and the sense signal Vout.

[0057] It should be noted that in the example related to FIG. 1, the phase difference (shift or delay) is about 41.7°, the phase component Φ is about 0°, and the phase component Φ' is about 41.7°. In the example related to FIG. 4, the phase difference (shift or delay) is about 26.2°, the phase component Φ is about 14.7°, and the phase component Φ' is about 40.9°. The drive signals (10 [MHz] and 20 [MHz]) and the position of the first electrode Tx (in the steering wheel 111 or in other components) in FIG. 1 and FIG. 4 are different between the example related to FIG. 1 and the example related to FIG. 4, and the state in which the capacitance Cft is present (FIG. 1) or the state in which the capacitance Cft is not present (FIG. 4) is different between the example related to FIG. 1 and the example related to FIG. 4 (i.e., the setting parameters are different), so the values ​​of the phase difference and the phase components Φ and Φ' are different between the example related to FIG. 1 and the example related to FIG. 4.

[0058] Conversely, when a liquid (e.g., a suspended conductor) (with Cf=100 [pF] and Rf=10 [Ω]) approaches and / or touches the second electrode Rx (of the sensor module 210 with various capacitances and resistances adjusted as described above), the composite impedance Z all This composite impedance Z (upon approach and / or contact with the liquid) changes to 0.147 + 0.0168i. all corresponds to a phase component Φ' of 6.5 degrees (6.5°). Thus, there is a slight phase difference (shift or delay) of only 8.2 degrees (8.2°), which is easily distinguishable from the phase difference (26.2°) mentioned above.

[0059] As explained above, the composite impedance Z between the first electrode Tx and the second electrode Rx allThe phase difference threshold of the phase component Φ′ of is preferably set to be twenty-six degrees (26°). When the phase difference (shift or delay) between the phase component Φ and the phase component Φ′ is equal to or greater than 26°, more specifically, when the phase difference is within a range of 26° to 359°, the decision circuit 250 is configured to determine whether the human body 112 approaches and / or touches the second electrode Rx (of the sensor module 210). When the phase difference is 360°, as described above, it may not be possible to determine whether 360° means that there is no phase difference or that there is a difference of one (or more) cycles of the sensed signal Vout. Thus, when the prescribed range is set as a phase difference (shift or delay) between the phase components Φ and Φ′ that is equal to or greater than 26°, more particularly set to be in the range of 26° to 359°, more particularly set to be in the range of 1° to 42°, and even more particularly set to be in the range of 26° to 42°, and the sensor module 210 and the sensor controller 220 include preselected parameters such as the sensor size, the physical distance (capacitance) between the first electrode Tx and the second electrode Rx, the impedance Zrx hanging from the second electrode Rx, and the prescribed frequency of the drive signal Vin, as described above, the approach and / or touch of the human body 212 to the second electrode Rx will produce a composite impedance Zrx. all Based on the phase difference (shift or delay) between the phase components Φ and Φ', i.e., the phase difference (shift or delay) between the drive signal Vin and the sense signal Vout, it is possible to clearly distinguish the approach and contact of a non-human object such as a liquid (a floating conductor) or a grounded conductor (metal).

[0060] The capacitances Cf and Cfr are substantially in series. In this way, the series combined capacitance of Cf and Cfr is expressed by "Cf×Cfr / (Cf+Cfr)". The combined capacitance of Cf and Cfr seen from the second electrode Rx depends largely on the smaller capacitance of the capacitances of Cfr and Cf. In this way, when the difference between the capacitances of Cf and Cfr is large and the detection target approaches and / or touches the second electrode Rx of the sensor module 210, the phase of the detection signal Vout may change significantly even if the detection target has not yet touched it, or the phase may change even when a detection target other than the human body 212 with a small capacitance approaches. Therefore, it is preferable that the capacitances of Cf and Cfr are approximately the same value. For example, if the human body 212 has a capacitance of the capacitor Cf (100 pF or more), the capacitance Cfr should also be 100 pF at the time of approach and / or contact (touch) with the second electrode Rx.

[0061] In general, there are many ways to detect the phase shift of a signal having a certain frequency. Furthermore, the detection resolution of the detection circuits (140 and 240) and the decision circuits (150 and 250) may be designed according to the closeness of the human body 212 (e.g., finger or hand) to the sensor module 210 (i.e., the steering wheel 211 having the second electrode Rx). Of course, the thickness of the rubber, leather, or other material on the steering wheel 211 and the thickness of the driving groove may also be taken into consideration. In some of the examples, the sensor module 210 (and the sensor controller 120) may detect the phase difference (shift) using a PLL circuit (a combination of a VCO and a phase detector). The output of the PLL is provided to a frequency counter (or an input capture counter) in the microcontroller. Some of the examples of the circuit options of the sensor module 210 will be described later.

[0062] The PLL baseline frequency is preferably adjusted to approximately 8 MHz using an RC circuit; i.e., the preferred frequency is between 7 MHz and 10 MHz. When the human body 212 (e.g., a finger or hand) comes close to the second electrode Rx, the frequency changes by a few thousand Hertz. A nonhuman target will not change the frequency of the PLL. It is preferable to have an active 4 pole band pass or low pass filter directly from the second electrode Rx before returning to the PLL. This configuration significantly reduces any noise, harmonics, or distortion that may creep into the sensed signal Vout from the second electrode Rx.

[0063] 5A and 5B, which provide exemplary graphs illustrating the impedance (phase) change (shift or delay) between the driving signal Vin and the sensed signal Vout of the sensor module 210 described above. Specifically, FIG. 5A illustrates a phase change or shift from a state in which the human body 212 has not yet approached and / or touched the steering wheel 211 having the second electrode Rx (corresponding to "X" (Z(No Touch)) and the phase is about 14.7°) until the human body 212 approaches and / or touches the steering wheel 211 having the second electrode Rx (corresponding to the largest dot (Z(Touch)) and the phase is about 40.9°). The phase change or phase shift when the human body 212 approaches and / or touches is indicated using a smaller dot (Z(No touch→Touch)) representing an increase in the capacitance Cfr. Afterwards, the capacitance Cfr reaches 100 pF at a phase shift of 40.9°, as shown by the largest dot (Z(touch)).

[0064] In contrast, FIG. 5B shows a phase change or shift from when the liquid has not yet approached and / or touched the steering wheel 211 having the second electrode Rx (corresponding to "X" (Z (No Touch)) and the phase is approximately 14.7°) to when the liquid (floating conductor) approaches and / or touches the steering wheel 211 having the second electrode Rx (corresponding to the largest dot (Z (Touch)) and the phase is approximately 6.5°). In this case, the phase angle becomes shallower (becomes smaller) as the liquid approaches or touches the steering wheel 211 having the second electrode Rx. The sensor module 210 generates a sensed signal Vout (i.e., a composite impedance Z all Since the 10-phase component (phase component) of the 10-phase component (phase component) provides a clear phase difference (shift or delay) (greater than 26°) between the 10-phase component (phase component) of ...

[0065] Now, referring to Fig. 6, Fig. 6 shows an example sensor circuit 300 including some of the components of the sensor module and controller shown in Fig. 1, Fig. 2, and / or Fig. 4. The sensor circuit 300 includes an Rx electrode (second electrode Rx) and a Tx electrode (first electrode Tx) touched by a finger 301, a low pass filter 310, a phase detector 320, a VCO (voltage controlled oscillator) 330, and a frequency counter 340. The combination of the phase detector 320 and the VCO 330 generally forms a PLL circuit.

[0066] The sensor module 110 or 210 (and the sensor controller 120 or 220) may detect the phase difference (shift) using a PLL circuit (combination of the VCO 330 and the phase detector 320). The output of the PLL is fed to a frequency counter 340 in, for example, a microcontroller. The PLL baseline frequency is preferably adjusted to approximately 8 MHz using an RC circuit. That is, the preferred frequency is anywhere between 7 MHz and 10 MHz. When a human body 112, 212, or 301 (e.g., a finger or hand) comes close to the first electrode Tx and the second electrode Rx, the frequency changes by a few thousand Hertz. A non-human object either does not change the frequency of the PLL or changes it in the opposite direction compared to a touch by a human body. Instead of the low-pass filter 310, an active 4 pole band pass filter may be used directly from the second electrode Rx before returning to the PLL. In addition, another 4 pole low-pass (or band pass) filter may be inserted between the VCO 330 and the Tx electrode (first electrode Tx). This configuration significantly reduces any noise, harmonics, or distortion that may creep into the sensed signal Vout from the second electrode Rx.

[0067] Regarding the specified frequency of the drive signal Vin, the optimal drive frequency (at which the phase changes the most) depends greatly (inversely proportionally) on the resistance component of the human body. Assuming that the resistance component of the human body is about 500 [Ω] to 510 [Ω], the optimal drive frequency (at which the phase changes the most) for detecting the human body is in the range of about 1 [MHz] to 100 [MHz], more specifically, about 10 [MHz]. Therefore, when the human body is the detection target, it is preferable to use the MHz band as the specified (drive) frequency of the drive signal Vin.

[0068] Alternatively, instead of the PLL circuit, a phase detector may be constructed using an XOR gate using the first electrode Tx and the second electrode Rx as inputs. The output pulse width of the XOR gate corresponds to the phase difference (shift). This output pulse width is measured with a high resolution, such as about 100 ps.

[0069] Another variation is to use a square wave of almost any frequency for the drive signal Vin of the first electrode Tx and measure the delay time with high resolution, which is the delay time from the input of the drive signal Vin to the first electrode Tx to the output of the sense signal Vout from the second electrode Rx. This method requires less analog circuitry such as filters. The baseline signal (from the capacitive sensor when there is no object in the vicinity of the capacitive sensor) has the delay time from the input of the drive signal Vin to the first electrode Tx to the output of the sense signal Vout from the second electrode Rx when there is no object in the vicinity of the sensor. When it is desired to detect light touches or touching by small hands, the measured delay amount may be a threshold for determining a valid human touch.

[0070] The above description is merely exemplary in nature and is not intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be implemented in various forms. Thus, while this disclosure includes several specific examples, other modifications will become apparent upon review of the drawings, specification, and claims below, and the true scope of the disclosure should not be so limited. It should be understood that one or more steps of a method may be performed in a different order (or simultaneously) without altering the principles of the disclosure. Furthermore, although each of the several embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure may be implemented in and / or combined with any feature of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more of the embodiments with each other remain within the scope of this disclosure.

[0071] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using a variety of terms including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "over," "under," and "disposed." Unless expressly described as "direct," when a relationship between a first element and a second element is described in the above disclosure, the relationship may be a direct relationship without any other intervening element between the first element and the second element, but it may also be an indirect relationship where there are one or more intervening elements (spatially or functionally) between the first element and the second element. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logic using non-exclusive OR (A OR B OR C), and not to mean "at least one of A, at least one of B, and at least one of C."

[0072] In the diagrams, the direction of the arrows, as indicated by the arrowhead, generally indicates the flow of information (such as data or instructions) that is the subject of the diagram. For example, when elements A and B exchange various information, and information sent from element A to element B is relevant to the diagram, the arrow may point in the direction from element A to element B. This unidirectional arrow does not imply that other information is not sent from element B to element A. Additionally, for information sent from element A to element B, element B may send element A a request for the information or an acknowledgment of receipt of the information.

[0073] In this application, including the definitions below, the term "module" or "controller" may be replaced with the term "circuitry." The term "module" may refer to, be part of, or include an application specific integrated circuit (ASIC), a discrete digital, analog, or mixed analog / digital integrated circuit, a combinatorial logic circuit, a field programmable gate array (FPGA), a processor circuit (shared, dedicated, or group) that executes code, a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit, other suitable hardware components that provide the described functionality, or a combination of some or all of the above, such as in a system on a chip.

[0074] A module may include one or more interface circuits. In some of the examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module of this disclosure may be distributed among multiple modules that are connected via the interface circuits. For example, multiple modules may enable load balancing. In a further example, a server module (also known as a remote module or cloud module) may perform some of the functions on behalf of a client module.

[0075] As explained above, the term code may include software, firmware, and / or microcode and may refer to programs, routines, functions, classes, data structures, and / or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all of the code from multiple modules. The term group processor circuit encompasses a processor circuit that executes some or all of the code from one or more modules in combination with additional processor circuits. References to multiple processor circuits encompass multiple processor circuits on separate dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or combinations thereof. The term shared memory circuit encompasses a single memory circuit that stores some or all of the code from multiple modules. The term group memory circuit encompasses a memory circuit that stores some or all of the code from one or more modules in combination with additional memories.

[0076] The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium as used herein does not include a transitory electrical or electromagnetic signal propagating through a medium (such as by a carrier wave), and therefore the term computer-readable medium may be considered to be tangible and non-transient. Non-limiting examples of non-transient and tangible computer-readable media are non-volatile memory circuits (such as flash memory circuits, erasable and programmable read-only memory circuits, or masked read-only memory circuits), volatile memory circuits (such as static random access memory circuits or dynamic random access memory circuits), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, Blu-ray discs).

[0077] The apparatus and methods described in this application may be implemented, in part or in whole, by a special purpose computer, which is created by configuring a general purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flow chart components, and other elements described above function as software specifications, which may be converted into a computer program by the routine work of a skilled technician or programmer.

[0078] A computer program includes processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. A computer program may also include or depend on stored data. A computer program may include a basic input / output system (BIOS) that interacts with the hardware of a special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0079] A computer program may include (i) parsed descriptive text, such as HTML (HyperText Markup Language), XML (Extensible Markup Language), or JSON (Javascript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, source code may be written using syntax from languages ​​including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java, Fortran, Perl, Pascal, Curl, OCaml, Javascript, HTML5 (HyperText Markup Language Fifth Edition), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash, Visual Basic, Lua, MATLAB®, SIMULINK®, and Python.

Claims

1. A sensor system for detecting a human body, the sensor system comprising: A first electrode; a second electrode connected to the first electrode via a capacitance; a driver circuit configured to generate a first signal having a defined frequency, the first signal being provided to the first electrode; a detection circuit configured to detect a second signal generated at the second electrode in response to the first signal being provided to the first electrode; a comparison circuit configured to compare the second signal with the first signal; the comparison circuit is configured to detect a touch and / or approach of the human body to at least one of the first electrode and the second electrode when a phase difference between the first signal and the second signal is within a defined range. Sensor system.

2. The sensor system of claim 1 , wherein the driver circuit is configured to select the defined frequency of the first signal from a plurality of frequencies.

3. The sensor system of claim 2 , wherein the capacitance is adjusted based on the selected defined frequency of the first signal.

4. 3. The sensor system of claim 2, wherein an impedance between the second electrode and ground potential is adjusted based on the selected defined frequency of the first signal.

5. The sensor system of claim 1 , wherein the second electrode is disposed in a steering wheel.

6. The sensor system of claim 5 , wherein the first electrode is disposed in the steering wheel.

7. 2. The sensor system of claim 1, wherein the comparison circuit is configured to detect the touch and / or the approach of the human body to the second electrode when the phase difference between the first signal and the second signal is within the specified range.

8. The sensor system of claim 1 , wherein the defined frequency of the first signal is in the range of 1 MHz to 100 MHz.

9. 2. The sensor system of claim 1, wherein the comparison circuit is configured to detect the touch and / or the proximity of a human body having an impedance within a specific range corresponding to a human body to at least one of the first electrode and the second electrode when the phase difference between the first signal and the second signal is within the specified range.

10. 2. The sensor system of claim 1, wherein the comparison circuit is configured to detect the touch and / or the proximity of the human body to at least one of the first electrode and the second electrode when an amplitude difference between the first signal and the second signal is within another specified range.

11. A method for detecting a human body, the method comprising: a driver circuit generating a first signal having a prescribed frequency; the drive circuit providing the first signal to a first electrode and a detection circuit; detecting, by the detection circuitry, a second signal generated at a second electrode capacitively coupled to the first electrode in response to the first signal being provided to the first electrode; a comparison circuit comparing a first phase of the first signal with a second phase of the second signal, respectively; and when a phase difference between the first phase and the second phase is within a defined range, the comparison circuit detects a touch and / or approach of the human body to at least one of the first electrode and the second electrode. method.

12. The method of claim 11 , wherein the defined frequency of the first signal is selected from a plurality of frequencies.

13. The method of claim 12 , wherein the capacitance is adjusted based on the selected defined frequency of the first signal.

14. 13. The method of claim 12, wherein an impedance between the second electrode and ground potential is adjusted based on the selected defined frequency of the first signal.

15. 12. The method of claim 11, wherein the touch and / or the approach of the human body to the second electrode is detected when the phase difference between the first signal and the second signal is within the defined range.

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