Sensor Device

Abstract

To provide a sensor device capable of coping with both of improvement of reproducibility of switching characteristics and a decrease in an average consumption current.SOLUTION: A sensor device 1 includes: a sensor element for converting a predetermined physical quantity to an electric signal; a drive circuit 20 for supplying a drive signal to the sensor element; a processing circuit 30 for outputting a binary result signal 31 obtained by binarizing an electric signal outputted from the sensor element; a determination circuit 60 for fetching the binary result signal 31 for plural times and performing predetermined logic determination processing; a latch circuit 70 for fetching an output signal of the determination circuit 60; an output terminal 80; and a control circuit 50 for outputting a control signal for performing intermittent control of at least one of the drive circuit 20 and the processing circuit 30 so as to repeat an operation period for supplying an operating current and a pause period for breaking an operating current at a predetermined period. When the predetermined determination processing is executed during the operation period and non-switching of an output logic of the determination circuit 60 in the middle of the operation period is determined, the operation period is interrupted and control is shifted to the pause period.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor device. [Background technology]

[0002] Hall elements are used in various applications because they can detect positions and angles as magnetic sensors without contact. One example of the application of Hall elements is a magnetic switch. A magnetic switch has, for example, a Hall element and a peripheral circuit including an amplifier and a comparator, and the Hall element and the peripheral circuit are integrated on a semiconductor chip. Magnetic switches are classified according to the method of detecting magnetism, and are known to include a bipolar magnetic field detection type that can detect magnetic fields of both poles, the south pole and the north pole, and an alternating magnetic field detection type that can detect an alternating magnetic field in which the south pole and the north pole alternate over time.

[0003] Generally, sensor elements have inherent noise, typically thermal noise. When the reproducibility of the operating point and return point (magnetoelectric conversion switching characteristics) caused by noise is low and the fluctuations are large, this leads to fluctuations in the detected amount, typically the detection position of the mechanism. In order to reduce the fluctuations in the detected amount and increase the detection accuracy of the sensor element, a technology has been proposed in which the sensor output is read multiple times and a judgment process is performed (see, for example, Patent Document 1).

[0004] Generally, a sensor element requires a large driving current to increase the sensitivity to raise the signal (S) level and to lower the noise (N) level to obtain a good S / N ratio (signal-to-noise ratio). On the other hand, when a sensor device is mounted on a battery-powered portable device, low current consumption is required. Therefore, in order to reduce the average current consumption of the sensor device as a whole, an intermittent driving technique is widely used that alternates between short operating periods (awake periods) during which detection operations are performed and long idle periods (sleep periods) during which only timekeeping operations are performed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 3-252526 [Patent Document 2] JP 2018-36252 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the multiple judgment technique described in Patent Document 1 is combined with the intermittent drive technique described in Patent Document 2, a longer operation period is required than that defined by (unit signal processing period) x (number of judgments). As the operation period becomes longer, the ratio of the operation period to the entire drive cycle, that is, the duty ratio, increases, weakening the effect of reducing the average current consumption.

[0007] In view of the above-mentioned circumstances, an object of the present invention is to provide a sensor device capable of improving the reproducibility of switching characteristics while reducing average current consumption through intermittent driving. [Means for solving the problem]

[0008] The sensor device according to the present invention comprises: A sensor device that operates in a drive cycle in which the sum of an operating period during which an operating current is supplied and a pause period during which the operating current is cut off is a constant value, A sensor element that converts a predetermined physical quantity into an electrical signal, a drive circuit that supplies a drive signal to the sensor element, and a processing circuit that outputs a binary result signal that is binarized by converting the electrical signal output from the sensor element. For each drive cycle, acquiring said binary result signal a plurality of times; A multiple number of times in which an individual judgment is made to judge whether or not the detection is performed by the sensor element for each of the binary result signals, with the maximum number of times being the number of times the binary result signals have been taken in, and a single judgment result indicating whether or not the detection is performed is obtained based on the results of the one or more individual judgments. A determination circuit for performing a determination process; The above-mentioned judgment result is shown a latch circuit that receives a binary output signal and outputs a voltage having a logical value; and at least one of the drive circuit and the processing circuit is controlled in response to the logical value of the voltage output from the latch circuit; The driving A control circuit that outputs a control signal for performing intermittent control so as to repeat the period, When the single determination result in the same drive cycle is obtained with a number of individual determinations less than the maximum number of the multiple determination processes based on the results of the individual determinations in the same drive cycle, Interrupt the operation period, Following said operating period The transition to a pause period is characterized by the above. Effect of the Invention

[0009] According to the present invention, it is possible to improve the reproducibility of switching characteristics while reducing the average current consumption through intermittent driving. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram of a sensor device according to an embodiment of the present invention. [Diagram 2] FIG. 1A is a relationship diagram showing the relationship between the amplified signal and the comparison reference voltage and the applied magnetic flux density of the sensor device of this embodiment; FIG. 1B is a relationship diagram showing the output voltage of the processing circuit and the applied magnetic flux density of the sensor device of this embodiment when VOUT=“H” and VOUT=“L”, respectively; and FIG. 1D is a relationship diagram showing the output voltage of the latch circuit and the applied magnetic flux density of the sensor device of this embodiment. [Diagram 3] 11 is a timing diagram showing a transition from a weak magnetic field to a strong magnetic field to a weak magnetic field in the sensor device according to the present embodiment. FIG. [Figure 4] FIG. 11 is a timing diagram showing a case where a magnetic flux density approximately equal to the operating point of a weak magnetic field of the sensor device according to the present embodiment is applied. [Diagram 5] 1A to 1C are graphs showing the relationship between the applied magnetic flux density and the average current consumption in a sensor device according to an embodiment of the present invention, and FIG. 1D is a graph showing the relationship between the applied magnetic flux density and the average current consumption in a sensor device of the prior art. [Figure 6] 1A is a relationship diagram showing the relationship between the number of matching determinations and the reproducibility of the operating point and the return point in the sensor device of this embodiment, and FIG. 1B is a relationship diagram showing the relationship between the number of matching determinations and the average current consumption in the sensor device of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A sensor device according to an embodiment of the present invention will be described below with reference to the drawings. The sensor device according to the embodiment includes a magnetic switch provided on a semiconductor substrate. In the description, the conversion characteristic from the magnetic flux density acting on the semiconductor substrate to an analog signal will be referred to as the "magnetoelectric conversion characteristic," and the conversion characteristic from the magnetic flux density to a logic signal will be referred to as the "magnetoelectric conversion switching characteristic." In addition, "*" will be used as a multiplication symbol. For example, "A*VSIG," which will be described later, means the product of A and VSIG.

[0012] FIG. 1 is a schematic diagram showing an example of the configuration of a sensor device 1 according to an embodiment of the present invention. The sensor device 1 is provided on a semiconductor substrate 2. The sensor device 1 includes a Hall element 10, a drive circuit 20, a processing circuit 30, a control circuit 50, a determination circuit 60, a latch circuit 70, and an output terminal 80.

[0013] The Hall element 10 is a magnetic sensor element, i.e., a magnetic sensor element, that outputs a Hall element output signal VSIG that is proportional to the Hall element drive current IDRV and the magnetic flux density B applied perpendicularly to the semiconductor substrate 2 (hereinafter referred to as the "applied magnetic flux density").

[0014] The drive circuit 20 is a circuit that supplies a Hall element drive current IDRV as a drive signal to the Hall element 10 as a sensor element. The drive circuit 20 is configured to control the on / off of the Hall element drive current IDRV that drives the Hall element 10 in accordance with the logical value of an input drive control signal 51. Here, the state in which the Hall element drive current IDRV is supplied, i.e., the on state, is referred to as the "operating state of the drive circuit 20," and the state in which the Hall element drive current IDRV is not supplied, i.e., the off state, is referred to as the "pause state of the drive circuit 20."

[0015] The processing circuit 30 is configured to switch between an active state and a pause state according to the logical value of the input drive control signal 51. The processing circuit 30 is configured to include, for example, an amplifier that amplifies the Hall element output signal VSIG as an input electrical signal, and a comparator that outputs a binary result signal 31 according to the magnitude relationship between the amplified Hall element output signal VSIG and a reference voltage.

[0016] In an operating state, the processing circuit 30 is configured to amplify the input Hall element output signal VSIG by an amplification factor A (A>0) and compare it with a predetermined reference voltage to determine the magnitude of the applied magnetic flux density B, and output a binary result signal 31 indicating the determination result. The predetermined reference voltage is switched to one of two different reference voltages, i.e., a first reference voltage or a second reference voltage (≠ first reference voltage), in accordance with the output logic signal 71, and is configured to have a so-called hysteresis characteristic. In a resting state, the processing circuit 30 cuts off the operating current required for the amplification and comparison operations to reduce current consumption, and the binary result signal 31 is set to a low level ( VCMP = “L”).

[0017] The control circuit 50 is configured to output a drive control signal 51 as a control signal according to the logical value of the output logic signal 71 output from the latch circuit 70, to switch the drive circuit 20 and the processing circuit 30 between an operating state or a dormant state, and to output a register clock signal 52 for the judgment circuit 60 to capture the binary result signal 31 multiple times during the operating period and a latch clock signal 53 for the latch circuit 70 to capture a judgment result signal 61 indicating the result of multiple judgments when transitioning from the operating period to the dormant period.

[0018] The judgment circuit 60 is configured to receive the binary result signal 31 as serial data in synchronization with the register clock signal 52, perform a predetermined multiple judgment process, and output a judgment result signal 61 as a binary output signal indicating the result of the multiple judgment process. In this embodiment, the predetermined multiple judgment process uses an all-match judgment process. The all-match judgment process described below is an example in which the binary result signal 31 is received four or more times, and when the judgment results match four times in a row, a transition is made between the detection state and the release state.

[0019] The latch circuit 70 is configured to latch the determination result signal 61 in synchronization with the latch clock signal 53 and output a voltage VOUT which is an output logic signal 71. The voltage VOUT is supplied to an output terminal 80 and is also supplied (feedback) to the processing circuit 30 and the control circuit 50.

[0020] Next, the magnetoelectric conversion characteristics of the sensor device 1 according to the embodiment of the present invention will be described with reference to the drawings.

[0021] 2(a) to 2(d) are magnetoelectric conversion characteristic diagrams showing the magnetoelectric conversion characteristics of the sensor device 1. More specifically, Fig. 2(a) is a relationship diagram showing the relationship of the amplified signal (A*VSIG) inside the processing circuit 30, the comparison reference voltage VBOP, and the comparison reference voltage VBRP with respect to the applied magnetic flux density B.

[0022] The amplified signal (A*VSIG) is proportional to the applied magnetic flux density B. Here, the applied magnetic flux density B that is the operating point in the magnetoelectric conversion characteristic is defined as the operating point BOP, and the applied magnetic flux density B that is the return point in the magnetoelectric conversion characteristic is defined as the return point BRP. In this case, the amplified signal (A*VSIG) at the operating point BOP and the return point BRP are the comparison reference voltages VBOP and VBRP, respectively. The difference between the operating point BOP and the return point BRP is the hysteresis width BHYS, and the difference between the comparison reference voltage VBOP and the comparison reference voltage VBRP is the comparison reference hysteresis voltage VBHYS.

[0023] FIG. 2(b) shows the voltage VCMP, which is the binary result signal 31 with respect to the applied magnetic flux density B when the voltage VOUT is at a high level (VOUT="H"). <BOPのとき , the voltage VCMP is low level ( VCMP=“L” ) When B>BOP, the voltage VCMP becomes high level (VCMP="H"). This magnetoelectric conversion characteristic itself has only one threshold value, the operating point BOP, and does not have hysteresis characteristics.

[0024] FIG. 2(c) shows the voltage VCMP, which is the binary result signal 31 with respect to the applied magnetic flux density B when the voltage VOUT is at a low level (VOUT="L"). <BRPのとき , the voltage VCMP is high level ( VCMP="H" ) When B>BRP, the voltage VCMP becomes low level (VCMP="L"). The difference between FIG. 2(c) and FIG. 2(b) is that the threshold is the return point BRP instead of the operating point BOP, and the logic of the voltage VCMP corresponding to the magnitude relationship with the threshold is reversed. b ), this magnetoelectric conversion characteristic itself has only one threshold value, the return point BRP, and does not have hysteresis characteristics.

[0025] 2(d) is a graph showing the relationship of the voltage VOUT to the applied magnetic flux density B. This magnetoelectric conversion characteristic has a hysteresis characteristic with two thresholds: the operating point BOP is the threshold for the “H” ⇒ “L” transition, and the return point BRP is the threshold for the “L” ⇒ “H” transition.

[0026] In this way, prior to the following description, the signal voltages of the various parts are defined with respect to the applied magnetic flux density B. Next, the operation of the sensor device 1 will be described with reference to the drawings.

[0027] Next, the operation of the sensor device 1 during transition from a weak magnetic field to a strong magnetic field to a weak magnetic field will be described. FIG. 3 is a timing diagram showing the operation timing when the sensor device 1 transitions from a weak magnetic field to a strong magnetic field to a weak magnetic field.

[0028] The instantaneous consumption current IDD becomes a predetermined operating current IDDA during the operation period and a predetermined standby current IDD0 during the standby period. During the standby period, only the minimum functions such as a reference clock circuit (not shown) inside the control circuit 50 are operating, and the standby current is kept low. The operation period TAW and the standby period TSL are defined, and the drive cycle TCYC, which is the sum of the operation period and the standby period, is defined. The drive cycle TCYC is fixed at a constant value, and the sum of the operation period TAW and the standby period TSL is the drive cycle TCYC.

[0029] The operation period TAW is defined as a natural number multiple of a predetermined processing period TSP. In this embodiment, the operation period TAWn can take a period between TSP and 4*TSP. That is, it is represented by the following formula (1). TAWn=n*TSP (n = 1, 2, 3, 4) (1)

[0030] The average consumption current for one cycle when the operation period TAWn is represented by each period is represented by the following formula (2). IDDn = IDD0 + IDDA*nTSP / TCYC (n = 1, 2, 3, 4) (2)

[0031] At this time, the standby period TSLn is represented by the following formula (3) respectively. TSLn = TCYC - TAWn = TCYC - n*TSP (n = 1, 2, 3, 4) (3)

[0032] At time t = 0, the drive control signal 51 is "L", and the sensor device 1 is in the standby state. Also, the applied magnetic flux density B is in a region satisfying B = Bw << BRP, VOUT = "H", that is, a weak magnetic field Bw. The binary result signal 31 is forcibly fixed to "L" because the sensor device 1 is in the standby state.

[0033] At time t=t31, the drive control signal 51 transitions from "L" to "H", and the sensor device 1 transitions from the idle state to the operating state. The applied magnetic flux density B exceeds the operating point BOP and increases to B>BOP, and the binary result signal 31 becomes "H" for the first time at time t=t32, the binary result signal 31 becomes "H" for the second time at time t=t33, the binary result signal 31 becomes "H" for the third time at time t=t34, and the binary result signal 31 becomes "H" for the fourth time at time t=t35. As long as the binary result signal 31 continues to be "H" in this way, the operating state continues up to a predetermined upper limit number of times. In terms of the all-time match determination process, this predetermined upper limit number is set to be equal to or greater than the number of times that a match is required.

[0034] Since the first to fourth binary result signals 31 were “H”, the determination result signal 61 was “ H ", which is latched by the latch circuit 70 by the rising edge of the latch clock signal 53 at t=t35, and VOUT="L", that is, the sensor device 1 transitions to a detection state indicating that it is detecting a strong magnetic field Bs (>>BOP), and the drive control signal 51 transitions to "L", and the sensor device 1 transitions from the operating state to the idle state.

[0035] The pause state continues until just before time t=t36, and the applied magnetic flux density B maintains B>BOP. At t=t36, the drive control signal 51 transitions to "H" again, and the sensor device 1 enters an operating state. Since the first binary result signal 31 is "L" here, the drive control signal 51 transitions to "L" at t=t37, and the sensor device 1 immediately transitions to a pause state. During the period from t=t37 to t310, the sensor device 1 operates in a pause state in which the operating state has been discontinued.

[0036] Subsequently, the pause state continues until immediately before time t = t311. During the period from t310 to t311, the applied magnetic flux density B decreases from the strong magnetic field Bs to the weak magnetic field Bw (<<BRP). At time t = t311, the drive control signal 51 transitions to "H" again, and the sensor device 1 transitions from the pause state to the operating state. At time t = t312, the first binary result signal 31 becomes "H", at time t = t313, the second binary result signal 31 becomes "H", at time t = t314, the third binary result signal 31 becomes "H", and at time t = t315, the fourth binary result signal 31 becomes "H". As long as the binary result signal 31 continues to be "H", the sensor device 1 continues to be in the operating state up to a predetermined upper limit number of times.

[0037] Since the first to fourth binary result signals 31 were "H", the determination result signal 61 becomes "H" and is latched by the latch circuit 70 at the rising edge of the latch clock signal 53 at t = t315. VOUT = "H", that is, the sensor device 1 transitions to the release state indicating that it has detected the weak magnetic field Bw. At the same time, the drive control signal 51 transitions to "L", and the sensor device 1 transitions from the operating state to the pause state.

[0038] Next, the operation when the applied magnetic flux density B is approximately equal to the threshold value, that is, the operating point BOP and the return point BRP, will be described. In the present embodiment, the applied magnetic flux density B for which the difference between the amplified signal (A*VSIG) and the comparison reference voltage VBOP is below the noise level is referred to as the applied magnetic flux density B "substantially equal to the operating point BOP". Also, the applied magnetic flux density B for which the difference between the amplified signal (A*VSIG) and the comparison reference voltage VBRP is below the noise level is referred to as the applied magnetic flux density B "substantially equal to the return point BRP".

[0039] Figure 4 is an operation timing diagram when an applied magnetic flux density substantially equal to the weak magnetic field ⇒ operating point is applied to the sensor device 1.

[0040] The difference between FIG. 3 and FIG. 4 is mainly that the applied magnetic flux density B is not in a state that is sufficiently large (strong magnetic field) with respect to the operating point BOP which is the threshold value or sufficiently small (weak magnetic field) with respect to the return point BRP which is the threshold value, and it is vulnerable to the influence of noise. In the embodiment of the present invention, the operation when a weak magnetic field (B = Bw) ⇒ an applied magnetic flux density B approximately equal to the operating point BOP (B ≒ BOP) is applied will be described with reference to the drawings.

[0041] At time t = 0, the drive control signal 51 is “L” and the sensor device 1 is in a standby state. The applied magnetic flux density B is in a state below the return point BRP (B < BRP), and VOUT = “H”, that is, in a weak magnetic field state. The binary result signal 31 is forcibly fixed at a low level, that is, the voltage VCMP = “L” because the sensor device 1 is in a standby period.

[0042] At time t = t41, the drive control signal 51 transitions to “H” and the sensor device 1 enters an operating state. The applied magnetic flux density B is B ≒ BOP, and due to the influence of noise, the binary result signal 31 randomly exceeds / does not exceed the threshold voltage VTH and can take “H” or “L”. At time t = t42, the first binary result signal 31 becomes “H”, at time t = t43, the second binary result signal 31 becomes “H”, and at time t = t44, the third binary result signal 31 becomes “L”. Since the binary result signal 31 outputs “L”, the operating state is not continued up to the specified number of times upper limit value, the drive control signal 51 transitions to “L”, the sensor device 1 interrupts the operating state and transitions to a standby state. At t = t45, the latch clock signal 53 is not output, the latch circuit 70 holds the current logic, and VOUT = “H”, that is, the release state is held.

[0043] The pause state continues until just before time t=t46, and the applied magnetic flux density B maintains B≈BOP. At the time t=t46, the drive control signal 51 transitions to "H" again, and the sensor device 1 enters an operating state. Here, the first binary result signal 31 is "L", and at t=t47, the drive control signal 51 transitions to "L", and the sensor device 1 immediately transitions to a pause state. During the period from t=t47 to t410, the sensor device 1 operates in a pause state in which the operating state has been terminated. At t=t410, the latch clock signal 53 is not output, and the latch circuit 70 holds the current logic, and holds VOUT="H", i.e., the released state.

[0044] Then, the pause state continues until just before time t=t411, and the applied magnetic flux density B maintains B≈BOP even during the period from t410 to t411. At time t=t411, the drive control signal 51 transitions to “H” again, and the sensor device 1 enters an operating state. At time t=t412, the first binary result signal 31 becomes “H”, at time t=t413, the second binary result signal 31 becomes “H”, at time t=t414, the third binary result signal 31 becomes “H”, and at time t=t415, the fourth binary result signal 31 becomes “H”. In this way, as long as the binary result signal 31 continues to be “H”, the operating state continues up to a predetermined upper limit number of times.

[0045] Since the first to fourth binary result signals 31 were “H”, the judgment result signal 61 becomes “H” and is latched into the latch circuit 70 by the rising edge of the latch clock signal 53 at t=t415, causing a transition to VOUT=“L”, i.e., the detection state, and the drive control signal 51 transitions to “L”, and the sensor device 1 transitions to the sleep state.

[0046] As described above, in FIG. 4, the applied magnetic flux density B becomes approximately equal to the operating point BOP, and the operation in which the sensor device 1 enters the detection state through a plurality of operating periods due to the influence of noise is shown. In this example, the first operating period has two coincidences, the second operating period has zero coincidences, and the third operating period has four coincidences and then transitions to the detection state. Since noise occurs randomly, the probability of n coincidences in the m-th operating period is determined probabilistically. Therefore, until the transition to the detection state through four coincidences, each state of zero coincidence (non-detection), one coincidence, two coincidences, and three coincidences occurs with a certain weight for each operating period.

[0047] The average current consumption when each state occurs is IDD1 for zero coincidence, IDD2 for one coincidence, IDD3 for two coincidences, and IDD4 for three coincidences. Next, the relationship between the applied magnetic flux density B and the current consumption IDD in the magnetic sensor device 1 will be described.

[0048] The difference in the average current consumption IDD with respect to the applied magnetic flux density B in the embodiment of the present invention and the prior art will be described. FIGS. 5(a) to (c) are explanatory diagrams of the average current consumption IDD with respect to the applied magnetic flux density B in the sensor device 1, and FIG. 5(d) is an explanatory diagram of the average current consumption IDD with respect to the applied magnetic flux density B in the prior art sensor device 200.

[0049] In FIG. 5(a), the region where the applied magnetic flux density B is weaker than the return point BRP (B < BRP) corresponds to, for example, the equipment cover 103 to which the magnetic article 100 in the figure is attached and the equipment housing 102 in which the sensor device 1 is incorporated. In the opening / closing detection mechanism 104 configured to be connected by a hinge 101 and be openable / closable, it corresponds to a sufficient "open" position. The region where the applied magnetic flux density B is stronger than the operating point BOP (B > BOP) corresponds to a sufficient "closed" position. The middle between the sufficient "open" position and the sufficient "closed" position corresponds to the region where BRP < B < BOP.

[0050] As shown in Fig. 5(a), in a situation where the opening / closing detection mechanism 104 is placed in a sufficient "open" position or a sufficient "closed" position, the binary result signal 31 is always "L", and the output logic signal 71 of the sensor device 1 does not change. Also, during most of the operation period of the opening / closing detection mechanism 104, it is often in the "open" position or "closed" position as described above. In the "open" position or "closed" position, the operation period is terminated without exceeding the threshold value in the first determination process, and multiple determination processes are not executed during the operation period. Since the operation period TAW = TSP, the average power consumption current is IDD1. The operating point BOP and the return point BRP have fluctuations such as being represented by a standard deviation σB in their threshold values due to the influence of noise inherent in the sensor device 1. Therefore, the operating point BOP and the return point BRP have a finite repeatability σB and can be expressed as a histogram of occurrence frequencies.

[0051] In Fig. 5(b), the average power consumption current during the "open" ⇒ "closed" state transition in the present invention will be described. The vertical axis represents the average power consumption current of the sensor device 1. IDD1 to IDD4 correspond to the current values in Figs. 3 and 4.

[0052] In the "open" state where the device cover 103 is fully open, the applied magnetic flux density B is sufficiently small, B = Bw << BOP, and the sensor device 1 is in a released state, that is, VOUT = "H". At this time, the processing circuit 30 operates with the magnetoelectric conversion characteristics of Fig. 2(c).

[0053] When the device cover 103 is gradually closed, the applied magnetic flux density B increases, and eventually B = BRP. At this stage, the determination circuit 60 is not detected even once, and the average power consumption current is IDD1.

[0054] When the device cover 103 is further closed, it reaches the left skirt of the histogram of the repeatability of the operating point BOP shown in Fig. 5(a). As the device cover 103 is further closed and approaches B = BOP, the probability of continuous detection and determination such as 1 detection, 2 matches, 3 matches, etc. becomes high in multiple determination processes in the determination circuit 60, and the average power consumption current increases from IDD1 and gradually approaches IDD4.

[0055] When the equipment cover 103 is further closed and B ≈ BOP is reached, the judgment circuit 60 makes a match judgment four times, the sensor device 1 goes into the detection state, i.e., VOUT="L", the processing circuit 30 switches to operation with the magnetoelectric conversion characteristics of Figure 2(b), and the average current consumption drops to IDD1.

[0056] After that, the device cover 103 is further closed to the completely "closed" state, and the applied magnetic flux density B is sufficiently large, B=Bs>>BOP. In this state, the processing circuit 30 still operates with the magnetoelectric conversion characteristics of FIG. 2(b), so the average current consumption remains at IDD1.

[0057] 5(c) will be used to explain the average current consumption during the "closed" to "open" state transition in the present invention. The vertical axis represents the average current consumption of the sensor device 1. As in FIG. 5(b), IDD1 to IDD4 correspond to the current values ​​in FIG. 3 and FIG.

[0058] When the device cover 103 is fully closed, that is, in the “closed” state, the applied magnetic flux density B is sufficiently large, B=Bs>>BOP, and the sensor device 1 is in the detection state, i.e., VOUT=“L.” At this time, the processing circuit 30 operates with the magnetoelectric conversion characteristics of FIG.

[0059] When the device cover 103 is gradually opened, the applied magnetic flux density B decreases, and eventually B=BOP. At this stage, the determination circuit 60 does not detect it even once, and the average current consumption is IDD1.

[0060] When the device cover 103 is opened further, the right foot of the histogram of the repeatability of BRP shown in Fig. 5(a) is reached. As the device cover 103 is opened further and approaches B = BRP, the probability that release will be judged consecutively in the multiple judgment process by the judgment circuit 60, such as release once, match twice, and match three times, increases, and the average current consumption increases from IDD1 and gradually approaches IDD4.

[0061] When the machine cover 103 is further opened and the applied magnetic flux density B reaches B≒BRP, the determination circuit 60 makes a four - time coincidence release determination. The sensor device 1 enters the release state, that is, VOUT = “H”. The processing circuit 30 switches to the operation with the magnetoelectric conversion characteristics in Fig. 2(c), and the average power consumption current decreases to IDD1.

[0062] After that, when the machine cover 103 is further opened to the fully “open” state and the applied magnetic flux density B becomes sufficiently small, B = Bw << BRP. In this state, since the processing circuit 30 still operates with the magnetoelectric conversion characteristics in Fig. 2(c), the average power consumption current maintains IDD1.

[0063] In Fig. 5(d), the opening - closing detection mechanism 204 is different from the opening - closing detection mechanism 104 (see Fig. 5(a)) in that it has a sensor device 200 instead of the sensor device 1 (see Fig. 5(a)), but is substantially the same in other aspects. The sensor device 200 executes the determination process a large number of times four times during the operation period regardless of the opening - closing state of the machine cover, that is, the applied magnetic flux density B. Therefore, the operation period is TAW4 = 4TSP, and the average power consumption current is a constant value IDD4. This means that the same is true even at the “open” position and “closed” position that occupy most of the operation period. Compared with the average power consumption current of the sensor device 1 that can reduce the average power consumption current to IDD1 at the fully “open” position and “closed” position, the average power consumption current of the sensor device 200 is large.

[0064] Next, the effects of the invention according to this embodiment, that is, the improvement of the reproducibility of the switching point and the reduction of the effective average power consumption current in the sensor device 1 will be described.

[0065] Fig. 6(a) is a relational diagram showing the relationship between the reproducibility σB of the operating point BOP with respect to the number of coincidence determinations Nj in the sensor device 1, and Fig. 6(b) is a relational diagram showing the relationship between the average power consumption current with respect to the number of coincidence determinations Nj in the sensor device 1. Here, the number of coincidence determinations Nj in Figs. 6(a) and 6(b) is an arbitrary natural number.

[0066] In Fig. 6(a), Nj = 1, that is, the reproducibility σB of the operating point BOP and the return point BRP based on a single determination is defined as σB0. The reproducibility σB for an arbitrary number of coincidence determination times Nj can be expressed by the following equation (4) using the number of coincidence determination times Nj and the reproducibility σB0 of the operating point BOP and the return point BRP based on a single determination. σB = σB0 / √Nj (4)

[0067] Here, the reproducibility σB is a desired small characteristic that is ideally zero. From the above equation (4), it can be seen that the larger the number of coincidence determination times Nj, the smaller and more improved the reproducibility σB. Also, if σB0 is zero then σB will always be zero, the operating point BOP and the return point BRP will have no fluctuations, and the repetitive reproducibility of the detection / release operation will be perfect. For example, when Nj = 4, σB = 0.5 * σB0; when Nj = 16, σB = 0.25 * σB0; when Nj = 64, σB = 0.125 * σB0, etc., it is suppressed. On the other hand, the larger the number of coincidence determination times Nj, the larger the circuit scale of the determination circuit 60. Therefore, when setting the number of coincidence determination times Nj, it is preferable to appropriately consider at least one of the required specifications for the repetitive reproducibility of the detection / release operation and the allowable circuit scale of the determination circuit 60.

[0068] Subsequently, with reference to Fig. 6(b), the average power consumption will be described. The solid line L1 shown in Fig. 6(b) shows the relationship between the average power consumption and the number of coincidence determination times in the sensor device 1 when the applied magnetic flux density B is in a range that is sufficiently weak (B << BRP) or sufficiently strong (B >> BOP) with respect to the operating point BOP and the return point BRP where the applied magnetic flux density B becomes the switching point. The broken line L2 shows the relationship between the average power consumption and the number of coincidence determination times Nj in the conventional sensor device 200 (see Fig. 5(d)) (comparative example).

[0069] In the conventional sensor device 200, since the average power consumption IDD increases in proportion to the number of coincidence determination times Nj regardless of the applied magnetic flux density B, the average power consumption is IDDnj. That is, the average power consumption of the conventional sensor device 200 is shown by the broken line L2 in Fig. 6(b).

[0070] On the other hand, in the sensor device 1, the average power consumption current changes depending on the applied magnetic flux density B. More specifically, at the applied magnetic flux density B (see FIG. 4) close to the switching point (BOP, BRP) satisfying at least approximately equal to at least one of the operating point BOP and the return point BRP, the average power consumption current is in the range of not less than IDD1 and less than IDDnj, and at the applied magnetic flux density B (see FIG. 3) that is sufficiently weak (B << BRP) or sufficiently strong (B >> BOP) with respect to the switching point, the average power consumption current becomes IDD1. Therefore, in the sensor device 1, it is possible to reduce the average power consumption current in the conventional sensor device 200 ( = IDDnj) or less over the entire range of the applied magnetic flux density B.

[0071] As described above, in the present invention, even if the number of coincidence determination times Nj is set large according to the requirement specification of the repeatability of the detection / release operation, under the condition that a sufficiently weak / strong applied magnetic flux density B is applied with respect to the switching point, it has been shown that the average power consumption current IDD can be suppressed to be sufficiently small.

[0072] According to the present invention, the reproducibility of the switching point (operating point and return point) is improved by using a large number of comparison determinations, and the operation period in the intermittent drive is appropriately interrupted based on the physical quantity detection result, that is, by transitioning to the resting state, the average power consumption current during the period in which the physical quantity detection result does not change, which occupies most of the energization period of the sensor device, can be reduced. By applying the present invention, it is possible to provide a sensor device that can improve the energy efficiency toward extending the battery life of battery-driven devices and thus realizing a sustainable society.

[0073] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments as they are, and in the implementation stage, it can be implemented in various forms other than the above-described examples, and various omissions, replacements, and changes can be made without departing from the gist of the invention.

[0074] For example, in the above-mentioned sensor device 1, an example is shown in which the all-time coincidence judgment process is used for the predetermined multiple judgment process in the judgment circuit 60, but the predetermined multiple judgment process is not limited to the all-time coincidence judgment process. The predetermined multiple judgment process is an example of a judgment process for improving the reproducibility of an operating point that fluctuates greatly in a judgment result obtained only once. In other words, the predetermined multiple judgment process is any judgment process that can improve the reproducibility of an operating point that fluctuates greatly in a judgment result obtained only once, and other multiple judgment processes such as majority judgment may be used.

[0075] The above-mentioned sensor device 1 is a so-called unipolar detection type magnetic switch device, but may be configured as a bipolar detection type or alternating detection type magnetic switch device. When the sensor device 1 is configured as a magnetic switch device of another detection method, an appropriate logic circuit may be added to the rear stage of the processing circuit 30 so that the state transition is appropriately controlled.

[0076] In the above embodiment, the control circuit 50 is configured to be able to switch both the drive circuit 20 and the processing circuit 30 between an active state and a dormant state, but is not limited to this. The control circuit 50 may be configured to be able to switch the drive circuit 20 between an active state and a dormant state, and may be configured to be able to switch the processing circuit 30 between an active state and a dormant state.

[0077] In the above-described embodiment, the sensor device 1 is configured as a magnetic switch using the Hall element 10 as a sensor element, but the sensor element is not limited to the Hall element. The sensor element may be configured to include a magnetic sensor element other than the Hall element, such as a magnetoresistance (MR) element, a magneto-impedance (MI) element, or a fluxgate sensor. The sensor element is not limited to magnetism, and may be a sensor element that detects at least one physical quantity among various physical quantities such as temperature, humidity, pressure, infrared intensity, ultraviolet intensity, and visible light intensity.

[0078] These embodiments and their variations are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0079] 1: Sensor device 10: Hall element (magnetic sensor element, sensor element) VSIG: Hall element output signal (electrical signal) 20: Drive circuit 30: Processing circuit 31: Binary result signal 50: Control circuit 51: Drive control signal 60: Judgment circuit 70: Latch circuit 71: Output logic signal IDRV: Drive current (drive signal)

Claims

1. A sensor device that operates with a drive period in which the sum of an operating period during which an operating current is supplied and a pause period during which the operating current is cut off is a constant value, A sensor element for converting a predetermined physical quantity into an electrical signal; A drive circuit for supplying a drive signal to the sensor element; a processing circuit for outputting a binary result signal obtained by binarizing the electrical signal output from the sensor element; a determination circuit that performs multiple determination processing for each of the drive cycles, acquiring the binary result signal a plurality of times, performing individual determination for each of the binary result signals to determine whether or not the sensor element has detected the signal, the maximum number of times being the number of times the binary result signal has been acquired, and obtaining a single determination result indicating whether or not the sensor element has detected the signal, based on the results of the one or more individual determinations; a latch circuit which receives a binary output signal indicating the one judgment result from the judgment circuit and outputs a voltage having a logical value; a control circuit that outputs a control signal for intermittently controlling at least one of the drive circuit and the processing circuit to repeat the drive cycle in accordance with the logical value of the voltage output from the latch circuit; A sensor device characterized in that, when a single judgment result in a same drive cycle is obtained with a number of individual judgments that is less than the maximum number of the multiple judgment processing based on the results of the individual judgments in that drive cycle, the operating period in that drive cycle is interrupted and a transition is made to a sleep period following the operating period.

2. The sensor device according to claim 1 , wherein the sensor element is a magnetic sensor element.

3. 3. The sensor device according to claim 2, wherein the magnetic sensor element is a Hall element.

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