JP2004180286A - Magnetic field sensor, magnetic field detecting apparatus, and magnetic field detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field sensor which has a simple constitution to detect a bipolar magnetic field strength and consumes a low electric power. <P>SOLUTION: The magnetic field sensor is provided with a first switch portion which inputs a signal output from an electromagnetic conversion element to output the signal according to an applied magnetic field and outputs switching so that it becomes reverse-polar for a first and a second terms and for a third and fourth terms, a storage element whose both ends are connected to a pair of output terminals of an amplifier and which supports a voltage output from the amplifier, and a second switch portion which is insert-connected between one of the pair of output terminals and one terminal of the storage element, closes for the first term and for the third term, and opens for the second term and for the fourth term, and a switch output terminal which outputs a first polar output signal of the second switch portion for the second term and outputs a second polar output signal of the second switch portion for the fourth term. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a magnetic field sensor, a magnetic field detection method, and a magnetic field detection device capable of detecting the intensity of a magnetic field without depending on the polarity of the magnetic field.

  In recent years, there has been an increasing demand for magnetic field sensors as position sensors such as open / close detection devices and rotation detection devices that are mounted on small electronic devices such as foldable mobile phones, notebook personal computers, and digital still cameras. In a magnetic field sensor mounted on a small portable electronic device, it is necessary to reduce both the circuit scale and the current consumption.

  Generally, a magnetic field sensor is monolithically integrated and configured using a bipolar transistor or a CMOS device. Such a magnetic field sensor includes a magneto-electric conversion element that generates a voltage proportional to a magnetic field or a magnetic flux density, an amplifier that amplifies an output voltage of the magneto-electric conversion element, and a comparator that compares the output voltage of the amplifier with a predetermined reference voltage. And outputs to the outside a determination result as to whether or not the strength of the magnetic field detected by the magnetoelectric conversion element (hereinafter, referred to as a detected magnetic field) is greater than a predetermined magnetic field strength. As the magnetoelectric conversion element, a Hall element that outputs a voltage corresponding to the strength of a magnetic field or the density of a magnetic flux passing through the element or a magnetic resistance whose resistance value changes according to the strength of the magnetic field is used.

  In order to obtain accurate comparison results according to the strength of the magnetic field from the magnetic field sensor, the offset signal included in the signal output from the amplifier is suppressed, and the variation in the signal output from the amplifier for each magnetic field sensor (product) Needs to be kept small. There are mainly two factors that cause the offset signal. One is an offset signal component of the magneto-electric conversion element due to the influence of stress or the like of the sealing package, and the other is an input offset signal component of the amplifier.

  A method of compensating for the offset signal component of the magnetoelectric conversion element is disclosed in U.S. Pat. No. 4,037,150. That is, among the output terminals of the magnetoelectric conversion element having four geometrically equivalent terminals, the potential difference between two pairs of output terminals located at diagonal positions is determined by the first phase and the first phase in the synchronization signal serving as a detection trigger. The output is alternately exchanged with the second phase, and the output values are summed. The effective signal components are doubled because they have the same phase, and the offset signal components are canceled because they have the opposite phase.

  One of the factors that determine the strength of a magnetic field sensor is whether or not the magnetic field can be detected regardless of the polarity of the magnet incorporated in the product, that is, whether the detection can be performed in accordance with both polarities. If the magnetic field strength can be determined irrespective of the polarity of the magnet, it is not necessary to manage the orientation of the magnet when arranging the magnet in a position sensor or the like in which the magnet and the Hall IC are incorporated.

Hereinafter, a conventional magnetic field sensor disclosed in Japanese Patent Application Laid-Open No. H7-83699, which performs a magnetic field strength determination compatible with both polarities, will be described with reference to the drawings.
FIG. 4 shows a configuration example of a conventional magnetic field strength determination circuit capable of handling both polarities. As shown in FIG. 4, a conventional magnetic field sensor includes a magneto-electric conversion element (a Hall element in a conventional example) 101, a voltage amplifier 102 for amplifying an output voltage of the magneto-electric conversion element 101, and an output voltage from the voltage amplifier 102. A first Schmitt trigger circuit 103A that receives and outputs an output voltage that differs according to the threshold value, and a second Schmitt trigger that receives the output voltage from the voltage amplifier 102 by inverting the polarity of the input signal of the first Schmitt trigger circuit 103A. The circuit includes a circuit 103B and a logic latch circuit 104 that receives and latches output signals from the first Schmitt trigger circuit 103A and the second Schmitt trigger circuit 103B.

The operation of the conventional magnetic field sensor configured as described above will be described.
First, the Hall voltage generated at the output terminal of the magneto-electric conversion element 101 is amplified by the amplifier 102 in proportion to the magnetic flux density passing through the magneto-electric conversion element 101 to obtain an amplified voltage VH.
Next, the amplified voltage VH is inputted to the first Schmitt trigger circuit 103A and the second Schmitt trigger circuit 103B, and it is compared whether the value of the amplified voltage VH is larger than a set voltage value, and the judgment value is outputted. I do. The first Schmitt trigger circuit 103A and the second Schmitt trigger circuit 103B are equivalent. By inverting the polarities of the input signals with each other, the two Schmitt trigger circuits detect the levels of the magnetic field intensities of the N polarity and the S polarity. This is performed separately in 103A and 103B.

Next, the output values of the first Schmitt trigger circuit 103A and the second Schmitt trigger circuit 103B are input to the logic latch circuit 104. Thereafter, the logic latch circuit 104 outputs an output value obtained by performing an operation on the output values of the two Schmitt trigger circuits 103A and 103B corresponding to the N-polarity and S-polarity magnetic field strengths. Here, the output value from the logic latch circuit 104 is a binary value indicating whether or not the strength of the detection magnetic field is greater than the strength of the set magnetic field regardless of the polarity.
U.S. Pat. No. 4,037,150 JP-A-7-83699

  However, the conventional magnetic field sensor requires two sets of Schmitt trigger circuits as a voltage comparison circuit to detect the magnetic field strength corresponding to both polarities regardless of the polarity of the magnetic field. And it is difficult to reduce both.

  The present invention solves the above-mentioned conventional problems, and provides a low-power-consumption magnetic field sensor, a magnetic field detection device, and a magnetic field detection method with a simple configuration that is independent of the polarity of a magnetic field and that detects the strength of a bipolar magnetic field. The purpose is to:

  In order to solve the above problems, the present invention has the following configurations. According to the first aspect of the present invention, a signal according to an applied magnetic field, which is output from a magnetoelectric conversion element, is input, and a first period, a fourth period, a second period, and a second period of an external signal are input. A first switch unit that switches and outputs the opposite polarity during the period 3, an amplifier that amplifies an output signal of the first switch unit and outputs a signal to an output terminal pair, and an output of the amplifier. A first storage element having both ends connected to a terminal pair, and being inserted and connected between one of the output terminal pairs and one terminal of the first storage element, interlocked with the first period and the third period; A second switch unit that closes and opens in conjunction with the second period and the fourth period; and a signal of at least one of both ends of the second switch unit during the second period. Outputting a signal of a first polarity corresponding to the magnitude of the applied magnetic field; A switch output terminal for outputting a signal of at least one of both ends of the second switch unit and having a polarity opposite to the first polarity corresponding to the magnitude of the applied magnetic field during a period of 4; A magnetic field sensor comprising:

According to a second aspect of the present invention, there is provided a magneto-electric conversion element that includes a first terminal pair and a second terminal pair and outputs a signal corresponding to an applied magnetic field, and a first terminal pair of the magneto-electric conversion element. And the signal of the second terminal pair, and an external signal that defines first, second, third, and fourth periods, and the magnetoelectric conversion element is provided in a first period and a fourth period. A first switch unit that outputs a signal of the first terminal pair of the first and second terminals, and outputs a signal of the second terminal pair of the magnetoelectric conversion element during a second period and a third period; and an output of the first switch unit. An amplifier that amplifies a signal and outputs a signal to an output terminal pair; a first storage element having both ends connected to the output terminal pair of the amplifier; one of the output terminal pair and one of the first storage element; A second period, which is inserted and connected between the terminals and closed in conjunction with the first period and the third period of the externally applied signal; A second switch unit to open in conjunction with the beauty fourth period, the switch output terminal for outputting at least one signal of the second switch portion at both ends, a magnetic field sensor, characterized in that it comprises a.
In this specification, the first, second, third, and fourth periods occur once or repeatedly in this order.

  The invention according to claim 18 is characterized in that a first selection signal generator for generating a first selection signal in the first period and the fourth period, and a second selection signal in the second period and the third period. A second selection signal generator for generating a signal, a third selection signal generator for generating a third selection signal in the first period and the third period, and a second selection signal generator for generating a signal in the second period and the fourth period. A fourth selection signal generator for generating a fourth selection signal, a magneto-electric conversion element having a first terminal pair and a second terminal pair, and outputting a signal corresponding to the applied magnetic field; The signal of the first terminal pair and the signal of the second terminal pair of the conversion element, and the first selection signal and the second selection signal are individually input, and the first selection signal and the second selection signal are input during the first period and the fourth period. A first terminal that outputs a signal of a first terminal pair of the magnetoelectric conversion element and outputs a signal of a second terminal pair of the magnetoelectric conversion element during a second period and a third period; A switch unit, an amplifier for amplifying an output signal of the first switch unit and outputting a signal to an output terminal pair, a first storage element having both ends connected to the output terminal pair of the amplifier, and the output terminal The third selection signal is input and connected between one of the pair and one terminal of the first storage element, and is closed during a first period and a third period; a second period and a fourth period And a second switch unit that is connected to one terminal of the second switch unit, receives a fourth selection signal, opens in a first period and a third period, and opens in a second period and a third period. A fifth switch unit that closes during period 4 and a voltage of at least one of both ends of the second switch unit are input via the fifth switch unit, and a result of comparison with a predetermined value is output. A comparator, an output signal of the comparator during a second period, and a fourth period A judging circuit for outputting a logical sum signal of the output signal of the comparator definitive a magnetic field detecting device, characterized in that it comprises a.

According to a nineteenth aspect of the present invention, a signal corresponding to the applied magnetic field output from the magneto-electric conversion element is input, and the signals are reversed in the first period and the fourth period, and in the second period and the third period. A switching step of switching to output the polarity, an amplification step of amplifying and outputting the signal output in the switching step, and a voltage output in the amplification step in a first period and a third period. A holding step of holding the first storage element, and a signal component corresponding to a magnetic field between the voltage output in the amplification step and the voltage held in the first storage element during a second period and a fourth period. A comparison step of inputting an addition voltage in the addition step having opposite polarities to each other during a second period and a fourth period, and outputting a result of comparison with a predetermined value; Comparison in the period An output signal of the step, a magnetic field detection method characterized by having a determination step of outputting a logical sum signal of the output signal of the comparing step in the fourth period.
With this configuration, the offset signal component generated in the output of the magneto-electric conversion element is removed by using the structural symmetry of the magneto-electric conversion element, and the offset voltage accompanying the amplifier is removed to output the output signal of the magneto-electric conversion element. Can be taken out.
Regardless of whether the polarity of the magnetic field is N-pole or S-pole, the presence or absence of a signal can be determined.

  According to a third aspect of the present invention, in the magnetic field sensor according to the second aspect, the second switch unit includes an output terminal pair.

The invention according to claim 4 is the magnetic field sensor according to claim 2, further comprising a comparator that inputs a signal of the switch output terminal and outputs a result of comparison with a predetermined value. Magnetic field sensor.
The magnetic field sensor outputs a highly accurate binary detection signal by providing a comparator that inputs a signal from the switch output terminal and outputs a result of comparison with a predetermined value.

  According to a fifth aspect of the present invention, in the magnetic field sensor according to the fourth aspect, a different voltage is added to a signal of the switch output terminal in accordance with an output signal of the comparator. With this configuration, the comparator is provided with hysteresis, and the magnetic field or magnetic flux can be detected stably.

  The invention according to claim 6 is the magnetic field sensor according to claim 2, wherein the signal is inserted and connected between one terminal of the second switch unit and one input terminal of the comparator, and A fifth switch unit that opens in conjunction with the first and third periods and closes in conjunction with the second and fourth periods, and connects one of both ends of the second switch unit to a fifth terminal; And one of the pair of comparator input terminals is connected to the other of the pair of comparator input terminals via a second storage element. It is a magnetic field sensor. By storing the threshold voltage in the second storage element, the threshold value can be set in the comparator with a simple configuration.

  The invention according to claim 7 is the magnetic field sensor according to claim 6, further comprising a third switch unit having one end connected to one of both ends of the second storage element, and both ends of the second storage element. A fourth switch having one end connected to the other of the first switch, a voltage source for applying a first voltage to the other of the third switch, and a voltage different from the first voltage to the other of the fourth switch. And a voltage source for applying a voltage, wherein the third and fourth switch units are closed during the first period of the signal. Thus, the threshold voltage can be stored in the second storage element with a simple configuration, and the threshold value can be set in the comparator.

  According to an eighth aspect of the present invention, in the magnetic field sensor according to the seventh aspect, one of the first voltage value and the second voltage value is made different depending on an externally applied signal. is there. By adding a different voltage to the signal at the switch output terminal according to the output signal of the comparator, the magnetic field sensor can perform detection with hysteresis added.

A ninth aspect of the present invention is the magnetic field sensor according to the second aspect, wherein the first storage element is a capacitor.
The invention according to claim 10 is the magnetic field sensor according to claim 7, wherein the second storage element is a capacitor.
By using a capacitor as a storage element, a small-sized magnetic field sensor suitable for IC can be realized.

  According to an eleventh aspect of the present invention, in the magnetic field sensor according to the second aspect, further, a signal value of the switch output terminal is input, and a signal value of the signal supplied from the outside during a second period and a fourth period. A magnetic field sensor comprising a determination circuit that outputs a signal that has determined the above.

  According to a twelfth aspect of the present invention, in the magnetic field sensor according to the eleventh aspect, the determination circuit inputs a signal of the comparator output terminal to a D input terminal, and sets a first clock signal to a clock input terminal. A first flip-flop for inputting, holding a signal within the second period and outputting to a Q output terminal, and an input terminal for each of the comparator output terminal and the Q output terminal of the first flip-flop. A NOR logic circuit that inputs to a pair and outputs a NOR logic output, an output of the NOR logic circuit being input to a D input terminal, and a second clock signal being input to a clock input terminal; And a second flip-flop that holds a signal and outputs the signal to an output terminal, and outputs a second flip-flop output terminal signal.

According to a thirteenth aspect of the present invention, in the magnetic field sensor according to the eleventh aspect, the determination circuit inputs a signal of the comparator output terminal to a D input terminal and a first clock signal to a clock input terminal. A first flip-flop for inputting and holding a signal within the second period and outputting the signal to a Q output terminal; a signal input to the comparator output terminal to a D input terminal; and a second clock signal Is input to a clock input terminal, and a second flip-flop that holds a signal within the fourth period and outputs it to an output terminal; and Q outputs of the first and second flip-flops are individually input terminal pairs. And a NOR logic circuit for inputting the NOR logic circuit and outputting a NOR logic output, and outputting the NOR logic circuit output.
A determination circuit for inputting a signal from the switch output terminal and outputting a signal which determines a signal value of a signal applied from the outside in a second period and a fourth period is provided, so that the polarity of the magnetic field is N-pole or S-pole. However, the presence or absence of a signal can be determined.

  According to a fourteenth aspect of the present invention, in the magnetic field sensor according to the second aspect, the first switch unit outputs a first voltage terminal and a second voltage terminal that outputs a second voltage. And first, second, third and fourth input terminals, first and second output terminals, and are inserted and connected between the first voltage terminal and the first input terminal, and open and close in response to externally applied signals. A first switch element, a second switch element inserted and connected between the first voltage terminal and the second input terminal, which opens and closes in response to an externally applied signal, and inserted between the second voltage terminal and the third input terminal A third switch element that is connected and opens and closes in response to an externally supplied signal, a fourth switch element that is inserted between the second voltage terminal and the fourth input terminal and that opens and closes in response to an externally supplied signal; Inserted between the first output terminal and the first input terminal; A fifth switch element that opens and closes in response to a signal supplied from the unit, a sixth switch element that is inserted and connected between the first output terminal and the second input terminal, and that opens and closes in response to an externally supplied signal; A seventh switch element that is inserted and connected between the output terminal and the third input terminal and that opens and closes in response to an externally supplied signal, and that is inserted between the second output terminal and the fourth input terminal and that is connected to an externally supplied signal; An eighth switch element that opens and closes, wherein one of a first terminal pair of the magneto-electric conversion element is connected to the first input terminal, and one of a second terminal pair of the magneto-electric conversion element is connected to the second input terminal. And the other of the first terminal pair of the magneto-electric conversion element is connected to the third input terminal, and the other of the second terminal pair of the magneto-electric conversion element is connected to the fourth input terminal. It is a magnetic field sensor.

According to a fifteenth aspect of the present invention, in the magnetic field sensor according to the fourteenth aspect, the first, third, sixth, and eighth switch elements close during first and fourth periods of an externally applied signal, The magnetic field sensor is characterized in that the second, fourth, fifth and seventh switches close during the second and third periods of an externally applied signal.
The first switch section is composed of eight switch elements, and two pairs of output terminals of the magneto-electric conversion element are exchanged between the first period and the fourth period, and between the second period and the third period. With this configuration, the offset signal component of the magneto-electric conversion element can be canceled.

The invention according to claim 16 is the magnetic field sensor according to claim 2, wherein the magnetoelectric conversion element is a Hall element.
The invention according to claim 17 is the magnetic field sensor according to claim 2, wherein the magnetoelectric conversion element is a magnetic resistance.
By using a Hall element or a magnetoresistance as the magnetoelectric conversion element, a small-sized magnetic field sensor suitable for IC can be realized.
The invention according to claim 20, further comprising a signal generator for outputting a signal for determining the first, second, third, and fourth periods to the first switch unit. A magnetic field sensor according to claim 1 or 2.

  According to the magnetic field sensor according to the present invention, one voltage comparator can cope with both polarities regardless of the polarity of the magnetic field, the magnetic field strength can be detected with a simple configuration, and current consumption can be reduced.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

<< Embodiment 1 >>
First Embodiment A magnetic field sensor according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram illustrating a configuration of the magnetic field detection device according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a magnetic field sensor according to the first embodiment, and reference numeral 3 denotes a signal generator.
The signal generator 3 includes a first selection signal generator 4, a second selection signal generator 5, a third selection signal generator 6, a fourth selection signal generator 9, and a first clock signal generator 7. And a second clock signal generator 8. Note that the signal generator 3 may be constituted by a microcomputer. The first selection signal generator 4 outputs a first selection signal a. The second selection signal generator 5 outputs a second selection signal b. The third selection signal generator 6 outputs a third selection signal c. The fourth selection signal generator 9 outputs a fourth selection signal d. The first clock signal generator 7 and the second clock signal generator 8 output a first clock signal CK1 and a second clock signal CK2, respectively. The four selection signals and the two clock signals are generated according to the timing chart shown in FIG.

  In the magnetic field sensor 1, 11 is a magnetoelectric conversion element, 12 is a voltage amplifier, 17 is a first storage element, 16 is a switch circuit (first switch section), 13 is a Schmitt trigger circuit, and 15 is a logic latch circuit (judgment circuit). ) And 54 are inverters, and 19 is a second inverter. In the first embodiment, the magnetoelectric conversion element 11 is a Hall element.

  The switch circuit 16 has eight switches 21A, 21B, 22A, 22B, 23A, 23B, 24A, and 24B. A power supply voltage is applied to one of the terminal pairs of the magnetoelectric conversion element 11 via the switch circuit 16, and the other is grounded. At this time, a signal voltage generated at another terminal pair of the magneto-electric conversion element 11 is applied to an input terminal of the voltage amplifier 12.

  Specifically, one end of the first switch 21A (first switch element) is connected to a first external terminal located at the first apex angle among the four apex angles of the magnetoelectric conversion element 11, The other end is connected to the power supply voltage input terminal, and is closed in synchronization with the first selection signal a. One end of the second switch 21B (second switch element) is connected to a second external terminal located at a second apex angle adjacent to the first apex angle of the magnetoelectric conversion element 11, and the other end is connected to a power supply. It is connected to the voltage input terminal, and is closed in synchronization with the second selection signal b. One end of the third switch 22A (third switch element) is connected to a third external terminal located at a third apex angle opposite to the first apex angle of the magnetoelectric conversion element 11, and the other end is grounded. The terminal is connected to the terminal and is closed in synchronization with the first selection signal a. The fourth switch 22B (fourth switch element) has one end connected to a fourth external terminal located at a fourth apex angle opposite to the second apex angle of the magnetoelectric conversion element 11, and the other end grounded. The terminal is connected to the terminal and is closed in synchronization with the second selection signal b.

  The fifth switch 23A (fifth switch element) has one end connected to the second external terminal of the magneto-electric conversion element 11, the other end connected to the non-inverting input terminal of the voltage amplifier 12, and a first selection signal. It is closed in synchronization with a. The sixth switch 23B (sixth switch element) has one end connected to the first external terminal of the magnetoelectric conversion element 11, the other end connected to the non-inverting input terminal of the voltage amplifier 12, and a second selection signal. It is closed in synchronization with b. The seventh switch 24A (seventh switch element) has one end connected to the fourth external terminal of the magnetoelectric conversion element 11, the other end connected to the inverting input terminal of the voltage amplifier 12, and a first selection signal a. In the closed state. The eighth switch 24B (eighth switch element) has one end connected to the third external terminal of the magnetoelectric conversion element 11, the other end connected to the inverting input terminal of the voltage amplifier 12, and the second selection signal b. In the closed state.

  In this configuration, while the first selection signal a is High, the switches 21A and 22A conduct, the switch 23A has one end connected to the non-inverting input terminal of the voltage amplifier 12, and the switch 24A has one end connected to the voltage amplifier 12. Connected to inverting input terminal. When the second selection signal b is High, the switches 21B and 22B are turned on, one end of the switch 23B is connected to the non-inverting input terminal of the voltage amplifier 12, and one end of the switch 24B is connected to the inverting input terminal of the voltage amplifier 12. Connected. The polarity of the voltage applied between the input terminals of the voltage amplifier 12 is opposite to each other during the period when the first selection signal a is High and the period when the second selection signal b is High.

  One end of a switch 18C (second switch unit) and one end of a switch 20D (fifth switch unit) are connected to the non-inverting output terminal of the voltage amplifier 12, and the other end of the switch 18C is connected to the first storage element 17. Connected to one end and terminal 101. The other end of the first storage element 17 is connected to the inverted output terminal of the voltage amplifier 12. The other end of the switch 20D is connected to the output terminal 100, and the voltage between the output terminals 100 and 101 is given to the Schmitt trigger circuit 13. The switch 18C is closed in synchronization with the third selection signal c, and the switch 20D is closed in synchronization with the fourth selection signal d.

The Schmitt trigger circuit 13 includes a comparator 130, a second storage element 33, a switch 34C (third switch), a switch 35C (fourth switch), a first MOS switch 36, and a second MOS switch 37. , A voltage source 38 and a first inverter 39.
One end (one electrode) of the second storage element 33 is connected to the terminal 100, and the other end (other electrode) is connected to the non-inverting input terminal of the comparator 130. The switch 34C has one end connected to one electrode of the second storage element 33 and the other end connected to one end of the first MOS switch 36 and the second MOS switch 37, and is synchronized with the third selection signal c. To the closed state. The switch 35C has one end connected to the other electrode of the second storage element 33 and the non-inverting input terminal of the comparator 130, the other end connected to the hysteresis value (set magnetic field) setting voltage source 38, and the third switch 35C. It is closed in synchronization with the selection signal c.

  One end of each of the first MOS switch 36 and the second MOS switch 37 is connected to the other end of the switch 34C, and the other end is connected to a different terminal of the setting voltage source 38. The output voltage of the terminal of the setting voltage source 38 to which the other end of the first MOS switch 36 is connected is higher than the output voltage of the terminal of the setting voltage source 38 to which the other end of the second MOS switch 37 is connected. . The output voltage of the terminal of the setting voltage source 38 to which the other end of the switch 35C is connected is lower than the output voltage of the terminal of the setting voltage source 38 to which the other end of the second MOS switch 37 is connected.

The inverting input terminal of the comparator 130 is connected to the terminal 101. The output terminal of the comparator 130 becomes the output terminal of the Schmitt trigger circuit 13.
The first inverter 39 has an input terminal connected to the output terminal of the logic latch circuit 15 (judgment circuit), an output terminal connected to the PMOS gate electrode of the first MOS switch 36, and a second MOS switch 37. Is connected to the gate electrode of the NMOS. The gate electrode of the NMOS of the first MOS switch 36 and the gate electrode of the PMOS of the second MOS switch 37 are connected to the output terminal of the logic latch circuit 15.

  The logic latch circuit 15 has a D input terminal connected to an output terminal of the comparator 130, a first flip-flop 51 receiving a first clock signal CK1 at a clock terminal, and an output from the comparator 130 at one input terminal. A two-input NOR logic circuit 52 receives a signal and the other input terminal receives an output signal from the first flip-flop 51; a D input terminal receives an output signal from the NOR logic circuit 52; And a second flip-flop 53 which receives the clock signal CK2 of The output terminal of the second flip-flop 53 becomes the output terminal of the logic latch circuit 15.

A second inverter 19 as an output buffer receiving an output signal of the second flip-flop 53 via an inverter 54 is connected to a stage subsequent to the logic latch circuit 15. The output terminal of the second inverter 19 becomes the output terminal of the magnetic field sensor 1.
In the first embodiment, the first storage element 17 and the second storage element 33 are capacitors. Hereinafter, the first storage element 17 and the second storage element 33 are described as a capacitor 17 and a capacitor 33, respectively.

Hereinafter, the operation of the magnetic field sensor configured as described above will be described.
FIG. 2 is a timing chart of a synchronization signal applied to the magnetic field sensor according to the first embodiment of the present invention. In FIG. 2, the first period is a state in which the first selection signal a is High, the second selection signal b is Low, the third selection signal c is High, and the fourth selection signal d is Low. A state where the first selection signal a is Low, the second selection signal b is High, the third selection signal c is Low, and the fourth selection signal d is High is defined as a second period. A state where the first selection signal a is Low, the second selection signal b is High, the third selection signal c is High, and the fourth selection signal d is Low is defined as a third period. A state in which the first selection signal a is High, the second selection signal b is Low, the third selection signal c is Low, and the fourth selection signal d is High is defined as a fourth period.

  In the first period, the switches 21A, 22A, 23A, 24A, 18C, 34C, and 35C conduct. In the first period, the switches 21A and 22A conduct to apply a potential to the magnetoelectric conversion element 11, and the switches 23A and 24A conduct to apply the output signal of the magnetoelectric conversion element 11 to the input terminal pair of the voltage amplifier 12. The voltage applied to the input terminal pair of the voltage amplifier 12 in the first period is the sum of the effective signal component and the offset signal component of the magneto-electric conversion element 11. Since the switch 18C is closed by the third selection signal c and the switch 20D is open by the fourth selection signal d, the signal voltage amplified by the voltage amplifier 12 is applied to both ends of the capacitor 17.

  On the other hand, the voltage of the voltage source 38 is applied to each terminal of the capacitor 33 because the switches 34C and 35C are closed. The voltage source 38 outputs a voltage obtained by dividing the power supply voltage by the resistors 140 to 145. The voltage at the connection between the resistors 142 and 143 is applied to the other end of the switch 35C. A voltage is applied to the other end of the switch 34C via the first MOS switch 36 or the second MOS switch 37. When the voltage at the input of the first inverter 39 is High, the first MOS switch 36 conducts, and when the voltage at the input of the first inverter 39 is Low, the second MOS switch 37 conducts. When the first MOS switch 36 is turned on, the voltage at the connection between the resistors 140 and 141 is supplied to the switch 34C. When the second MOS switch 37 is turned on, the voltage at the connection between the resistors 141 and 142 is applied. Thus, a predetermined voltage is applied to both ends of the capacitor 33. The voltage applied to both ends of the capacitor 33 corresponds to a threshold for detecting the strength of the detection magnetic field.

  In the second period, the switches 21A, 22A, 23A, 24A, 18C, 34C, and 35C are open. The switches 21 </ b> B and 22 </ b> B are turned on to apply a potential to the magnetoelectric conversion element 11. The switches 23 </ b> B and 24 </ b> B are turned on, and the output signal of the magnetoelectric conversion element 11 is given to the input terminal pair of the voltage amplifier 12. On the other hand, since the switch 18C is opened by the third selection signal c and the switch 20D is closed by the fourth selection signal d, the signal voltage amplified by the voltage amplifier 12 is connected to the series connection of the capacitor 17 and the capacitor 33. Given at both ends.

  The polarity of the effective signal component applied to the input terminal pair of the voltage amplifier 12 during the second period is opposite to the polarity of the effective signal component applied to the input terminal pair of the voltage amplifier 12 during the first period. On the other hand, the polarity of the offset signal component of the magnetoelectric conversion element 11 is the same in the first period and the second period.

  When the switch 18C is opened, the voltage at the connection between the capacitor 17 and the inverted output terminal of the voltage amplifier 12 is relatively positive with respect to the connection (terminal 101) between the switch 18C and the capacitor 17. And In this state, the polarity of the voltage at the non-inverting output terminal becomes further positive with respect to the inverting output terminal of the voltage amplifier 12. Accordingly, in the second period, the signal of the first period and the signal of the second period are added and output between the terminal 100 and the terminal 101. The voltage at terminal 100 is higher than the voltage at terminal 101.

  If the voltage at the input terminal pair of the voltage amplifier 12 is amplified and the voltage taken out from the output terminal pair always has an offset voltage of the voltage amplifier 12, the offset voltage is changed by the switch 18C between the first period and the second period. The opposite polarity is applied to both ends. The output voltage between the terminal 100 and the terminal 101 in the second period does not include the offset voltage component because the offset voltage component is substantially canceled. The offset signal component of the magnetoelectric conversion element 11 applied to the input terminal pair of the voltage amplifier 12 has the same polarity in the first period and the second period. Between the output terminals 100 and 101, the offset signal component of the magnetoelectric conversion element 11 has the opposite polarity between the first period and the second period. The output voltage between the terminal 100 and the terminal 101 in the second period does not include the offset signal component because the offset signal component is substantially canceled.

  Thus, in the output voltage between the terminal 100 and the terminal 101 in the second period, the offset voltage component of the magnetoelectric conversion element 11 and the voltage amplifier 12 is canceled, and the effective signal component is doubled.

Next, a voltage obtained by subtracting the voltage (threshold) across the capacitor 33 from the sum of the output voltage of the voltage amplifier 12 and the voltage of the capacitor 17 is applied to the input terminal pair of the comparator 130.
When the voltage value (the voltage value obtained by subtracting the voltage of the inverting influential terminal from the voltage of the non-inverting input terminal) applied to the comparator 130 is equal to or greater than zero (for example, when a magnetic field of S polarity having a strength equal to or greater than a threshold is detected) The comparator 130 outputs a High value which is one of the binary voltages. In the first period, the voltage across the capacitor 33 (the voltage obtained by subtracting the voltage at the inverting input terminal from the voltage at the non-inverting input terminal of the comparator 130) is negative, and the output of the comparator 130 is low. .

  In the third period, the switches 21B, 22B, 23B, 24B, 18C, 34C, and 35C conduct. As in the second period, the switches 21B and 22B are turned on, and a potential is applied to the magnetoelectric conversion element 11. The switches 23 </ b> B and 24 </ b> B are turned on, and the output signal of the magnetoelectric conversion element 11 is given to the input terminal pair of the voltage amplifier 12. Since the switch 18C is closed by the third selection signal c and the switch 20D is open by the fourth selection signal d, the signal voltage amplified by the voltage amplifier 12 is applied to both ends of the capacitor 17.

  In the fourth period, the switches 21B, 22B, 23B, 24B, 18C, 34C, and 35C are open. As in the first period, the switches 21A and 22A are turned on to apply a potential to the magnetoelectric conversion element 11. The switches 23 </ b> A and 24 </ b> A are turned on, and the output signal of the magnetoelectric conversion element 11 is given to the input terminal pair of the voltage amplifier 12. Since the switch 18C is opened by the third selection signal c and the switch 20D is closed by the fourth selection signal d, the signal voltage amplified by the voltage amplifier 12 is applied to both ends of the series connection of the capacitor 17 and the capacitor 33. Given.

  The polarity of the effective signal component applied to the input terminal pair of the voltage amplifier 12 during the fourth period is opposite to the polarity of the effective signal component applied to the input terminal pair of the voltage amplifier 12 during the third period. On the other hand, the polarity of the offset signal component of the magnetoelectric conversion element 11 is the same in the third period and the fourth period.

  The polarity of the signal applied to the voltage amplifier 12 during the first and second periods and the polarity of the signal applied during the third and fourth periods are opposite to each other. If the voltage of the terminal 100 is lower than the voltage of the terminal 101 in the second period, the voltage of the terminal 100 is higher than the voltage of the terminal 101 in the fourth period. In the fourth period, the comparator 130 outputs High when the input voltage value is equal to or more than zero. When an S-polarity magnetic field is detected in the second period, an N-polarity magnetic field is detected in the fourth period. By making the time (detection cycle) from the first period to the fourth period sufficiently shorter than the fluctuation period of the detection magnetic field to be detected, one of the second period and the fourth period can be obtained. It can be determined whether the magnetic field strength of the detection magnetic field is larger than a predetermined value. The magnetic field sensor according to the first embodiment can determine whether or not the strength of the detected magnetic field is greater than a predetermined value regardless of the polarity of the detected magnetic field.

  The output of comparator 130 is provided to logic latch circuit 15. The logic latch circuit 15 is individually supplied with a first clock signal CK1 and a second clock signal CK2 for latching the output signal of the comparator 130 during the second period and the fourth period. The logic latch circuit 15 latches an input signal when the clock signal falls.

  First, a value corresponding to the output state of the comparator 130 is held at the Q output of the first flip-flop 51 by the first clock signal CK1. The Q output signal and the output signal of comparator 130 are applied to NOR logic circuit 52. When both values are Low, the output of the NOR logic circuit 52 is High. The output of the NOR logic circuit 52 is held at the output of the second flip-flop 53 by the second clock signal CK2.

  If the output of the comparator 130 is High in any of the second and fourth periods, the Q output signal of the second flip-flop 53 is Low. If the output of the comparator 130 is Low in both the second and fourth periods, the Q output signal of the second flip-flop 53 is High. The Q output signal of the second flip-flop 53 is extracted as an output signal of the logic latch circuit 15.

The output signal of the logic latch circuit 15 is supplied to the input of the inverter 54, the input of the first inverter 39 in the Schmitt trigger circuit 13, the NMOS gate electrode of the first MOS switch 36, and the PMOS of the second MOS switch 37. To the gate electrode. The output signal of inverter 54 is provided to the input of second inverter 19.
When the output of the logic latch circuit 15 is High, a current drive signal directed to the outside is extracted from the output of the second inverter 19. When the output of the logic latch circuit 15 is Low, a current signal from the outside toward the output of the second inverter 19 is supplied.

  When the output of the logic latch circuit 15 is High, the voltage at the input of the first inverter 39 becomes High, the first MOS switch 36 is turned on, and the switch 34C connected to the first MOS switch 36 is turned on. Is supplied with the voltage at the connection between the resistors 140 and 141. When the output of the logic latch circuit 15 is Low, the voltage at the input of the first inverter 39 becomes Low, the second MOS switch 37 is turned on, and the other of the switch 34C connected to the second MOS switch 37 is turned on. The end is supplied with the voltage of the connection between the resistor 141 and the resistor 142.

  As described above, when no magnetic field (or magnetic flux) is detected in any of the second and fourth periods, the voltage at the connection between the resistors 140 and 141 is applied to one of the capacitors 33, and the second or fourth period When a magnetic field (or a magnetic flux) is detected in step (1), the voltage at the connection between the resistors 141 and 142 is applied to one of the capacitors 33. By making the voltage value applied to one of the capacitors 33 different according to the output signal in this way, the comparison level of the comparator 130 can have hysteresis.

The magnetic field detection device of the first embodiment can output a binary value indicating whether or not the strength of the detection magnetic field is greater than a predetermined value, regardless of the polarity of the detection magnetic field.
The magnetic field detection device according to the first embodiment applies a high hysteresis voltage to comparator 130 when no magnetic field is detected, and applies a low hysteresis voltage to comparator 130 once the magnetic field is detected. Therefore, the magnetic field can be detected stably.
Since the magnetic field detection device of the first embodiment has only one voltage comparator, the current consumption is small and the circuit scale is small.

<< Embodiment 2 >>
FIG. 3 is a circuit diagram showing a configuration of the magnetic field detection device according to the second embodiment of the present invention. The magnetic field detection device according to the first embodiment is obtained by replacing the magnetic field sensor 1 with a magnetic field sensor 2. The magnetic field sensor 2 of the second embodiment is obtained by replacing the logic latch circuit 15 of the magnetic field sensor 1 of the first embodiment (FIG. 1) with a logic latch circuit 150. In other respects, the magnetic field sensor of the second embodiment is the same as that of the first embodiment. In FIG. 3, the same blocks as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  The output of the comparator 130 of the Schmitt trigger circuit 13 is connected to the D input terminals of the first flip-flop 510 and the second flip-flop 511. The first clock signal CK1 is supplied to a clock input terminal of the first flip-flop 510. Further, a second clock signal CK2 is supplied to a clock input terminal of the second flip-flop 511. The Q output signals of the first flip-flop 510 and the second flip-flop 511 are provided to the NOR logic circuit 520. When the signals detected by the first clock signal CK1 and the second clock signal CK2 are both Low, the output of the logic latch circuit 150 is High. When one of the signals detected by the first clock signal CK1 and the second clock signal CK2 is High, the output of the logic latch circuit 150 is Low.

The magnetic field detection device according to the second embodiment has the same effects as the magnetic field detection device according to the first embodiment.
In the first and second embodiments, the magnetoelectric conversion element 11 is a Hall element, but may be a magnetoresistance or another magnetoelectric conversion element.
In the magnetic field sensor 1 of the first embodiment and the magnetic field sensor 2 of the second embodiment, the configuration may be such that the magnetoelectric conversion element 11 and the second inverter 19 are provided outside the magnetic field sensor.
The first switch unit 16 may be configured to include the signal generator 3.

  INDUSTRIAL APPLICABILITY The magnetic field sensor, the magnetic field detection method, and the magnetic field detection device of the present invention are useful as a magnetic field sensor, a magnetic field detection method, and a magnetic field detection device that can detect the strength of a magnetic field without depending on the polarity of the magnetic field.

FIG. 1 is a block diagram illustrating a configuration of a magnetic field detection device according to a first embodiment of the present invention. Timing chart of a synchronization signal applied to the magnetic field sensors according to the first and second embodiments of the present invention FIG. 4 is a block diagram illustrating a configuration of a magnetic field detection device according to a second embodiment of the present invention. Configuration diagram showing a conventional magnetic field strength determination circuit capable of handling both polarities

Explanation of reference numerals

1, 2 magnetic field sensor 3 signal generator 4 first selection signal generator 5 second selection signal generator 6 third selection signal generator 7 first clock signal generator 8 second clock signal generator 9 Fourth selection signal generator 11 magnetoelectric conversion element 12 voltage amplifier 13 Schmitt trigger circuit 15, 150 logic latch circuit (judgment circuit)
16. Switch circuit (first switch unit)
17 First storage element 18C Switch (second switch unit)
19 second inverter 20D switch (fifth switch unit)
21A First switch (first switch element)
21B 2nd switch (2nd switch element)
22A Third switch (third switch element)
22B Fourth switch (fourth switch element)
23A Fifth switch (fifth switch element)
23B Sixth switch (Sixth switch element)
24A seventh switch (seventh switch element)
24B Eighth Switch (Eighth Switch Element)
33 second storage element 34C switch (third switch unit)
35C switch (fourth switch unit)
36 first MOS switch 37 second MOS switch 38 voltage source 39 first inverter 54 inverter 51, 510 first flip-flop 52, 520 NOR logic circuit 53, 511 second flip-flop 100, 101 output terminal 101 Magnetoelectric conversion element 102 Voltage amplifier 103A First Schmitt trigger circuit 103B Second Schmitt trigger circuit 104 Logic latch circuit 130 Comparator 140-145 Resistance

Claims (20)

A signal corresponding to an applied magnetic field, which is output from the magnetoelectric conversion element, is input, and the polarity of the signal from the outside is reversed in the first period and the fourth period, and in the second period and the third period. A first switch unit for switching and outputting
An amplifier for amplifying an output signal of the first switch unit and outputting a signal to an output terminal pair;
A first storage element having both ends connected to an output terminal pair of the amplifier;
It is inserted and connected between one of the output terminal pairs and one terminal of the first storage element, and is closed in conjunction with the first period and the third period, and the second period and the fourth period A second switch unit that opens in conjunction with
In the second period, a signal of a first polarity corresponding to the magnitude of the applied magnetic field, which is a signal of at least one of both ends of the second switch unit, is output, and in the fourth period, A switch output terminal for outputting a signal having a polarity opposite to the first polarity, which is a signal of at least one of both ends of the second switch unit and corresponds to the magnitude of the applied magnetic field;
A magnetic field sensor comprising: A magneto-electric conversion element having a first terminal pair and a second terminal pair and outputting a signal corresponding to the applied magnetic field;
A signal of a first terminal pair and a signal of a second terminal pair of the magnetoelectric conversion element, and an external signal that defines first, second, third, and fourth periods are inputted, and the first period is inputted. And a first switch unit that outputs a signal of the first terminal pair of the magneto-electric conversion element during a fourth period and outputs a signal of the second terminal pair of the magneto-electric conversion element during a second period and a third period. When,
An amplifier for amplifying an output signal of the first switch unit and outputting a signal to an output terminal pair;
A first storage element having both ends connected to an output terminal pair of the amplifier;
The signal is inserted and connected between one of the output terminal pairs and one terminal of the first storage element, and is closed in conjunction with a first period and a third period of the externally applied signal, and is closed in a second period and a fourth period. A second switch unit that opens in conjunction with the period of
A switch output terminal that outputs at least one signal of both ends of the second switch unit;
A magnetic field sensor comprising: The magnetic field sensor according to claim 2,
A magnetic field sensor, wherein the second switch unit includes an output terminal pair. The magnetic field sensor according to claim 2, further comprising:
A magnetic field sensor comprising: a comparator that receives a signal from the switch output terminal and outputs a result of comparison with a predetermined value. 5. The magnetic field sensor according to claim 4, wherein a different voltage is added to a signal at the switch output terminal according to an output signal of the comparator. 3. The magnetic field sensor according to claim 2, wherein the first and third periods of the externally applied signal are inserted and connected between one terminal of the second switch unit and one input terminal of the comparator. 4. And a fifth switch section that opens in conjunction with the second switch section and closes in conjunction with the second and fourth periods, and one of both ends of the second switch section is connected to a comparator input through a fifth switch section. A magnetic field sensor, wherein the magnetic field sensor is connected to one of a pair of terminals, and the other of the second switch unit is connected to the other of the pair of comparator input terminals via a second storage element. The magnetic field sensor according to claim 6, further comprising:
A third switch unit having one end connected to one of both ends of the second storage element;
A fourth switch unit having one end connected to the other end of both ends of the second storage element;
A voltage source for applying a first voltage to the other of the third switch unit;
A voltage source that supplies a voltage different from the first voltage value to the other of the fourth switch unit;
A magnetic field sensor, wherein the third and fourth switch units are closed during the first period of a signal. 8. The magnetic field sensor according to claim 7, wherein one of the first voltage value and the second voltage value is made different according to an externally applied signal. 3. The magnetic field sensor according to claim 2, wherein the first storage element is a capacitor. 8. The magnetic field sensor according to claim 7, wherein the second storage element is a capacitor. The magnetic field sensor according to claim 2, further comprising:
A magnetic field sensor comprising: a determination circuit that receives a signal from the switch output terminal and outputs a signal that determines a signal value of a signal supplied from outside in a second period and a fourth period. The magnetic field sensor according to claim 11, wherein the determination circuit comprises:
A first input terminal for inputting a signal from the comparator output terminal to a D input terminal, inputting a first clock signal to a clock input terminal, holding the signal within the second period, and outputting the signal to a Q output terminal; Flip-flop and
A NOR logic circuit that individually inputs the comparator output terminal and the Q output terminal of the first flip-flop to an input terminal pair and outputs a NOR logic output;
A second flip-flop that inputs the output of the NOR logic circuit to a D input terminal, inputs a second clock signal to a clock input terminal, holds the signal within the fourth period, and outputs it to an output terminal And
A magnetic field sensor for outputting a second flip-flop output terminal signal. The magnetic field sensor according to claim 11, wherein the determination circuit comprises:
A first input terminal for inputting a signal from the comparator output terminal to a D input terminal, inputting a first clock signal to a clock input terminal, holding the signal within the second period, and outputting the signal to a Q output terminal; Flip-flop and
A second inputting a signal from the comparator output terminal to a D input terminal, inputting a second clock signal to a clock input terminal, holding the signal within the fourth period, and outputting the signal to an output terminal; Flip-flops,
A NOR logic circuit that individually inputs the Q outputs of the first and second flip-flops to an input terminal pair and outputs a NOR logic output,
A magnetic field sensor for outputting the NOR logic circuit output. The magnetic field sensor according to claim 2,
The first switch unit includes:
A first voltage terminal that outputs a first voltage;
A second voltage terminal that outputs a second voltage;
First, second, third and fourth input terminals;
First and second output terminals;
A first switch element inserted and connected between the first voltage terminal and the first input terminal and opening and closing in response to a signal supplied from outside;
A second switch element that is inserted and connected between the first voltage terminal and the second input terminal and that opens and closes in response to an externally applied signal;
A third switch element that is inserted and connected between the second voltage terminal and the third input terminal and that opens and closes in response to an externally applied signal;
A fourth switch element that is inserted and connected between the second voltage terminal and the fourth input terminal and that opens and closes in response to an externally applied signal;
A fifth switch element that is inserted and connected between the first output terminal and the first input terminal and that opens and closes in response to an externally applied signal;
A sixth switch element that is inserted and connected between the first output terminal and the second input terminal and that opens and closes in response to an externally applied signal;
A seventh switch element inserted and connected between the second output terminal and the third input terminal and opening and closing in response to a signal supplied from outside;
An eighth switch element that is inserted and connected between the second output terminal and the fourth input terminal and that opens and closes in response to an externally applied signal;
Connecting one of a first terminal pair of the magnetoelectric conversion element to the first input terminal;
Connecting one of a second terminal pair of the magnetoelectric conversion element to the second input terminal;
Connecting the other of the first terminal pair of the magnetoelectric conversion element to the third input terminal,
A magnetic field sensor, wherein the other of the second pair of terminals of the magnetoelectric conversion element is connected to the fourth input terminal. 15. The magnetic field sensor according to claim 14, wherein the first, third, sixth, and eighth switch elements are closed during the first and fourth periods of an externally applied signal, and the second, fourth, fifth, and fifth switch elements are closed. A magnetic field sensor, wherein the seventh switch is closed during the second and third periods of an externally applied signal. 3. The magnetic field sensor according to claim 2, wherein said magnetoelectric conversion element is a Hall element. 3. The magnetic field sensor according to claim 2, wherein the magnetoelectric conversion element is a magnetic resistance. A first selection signal generator that generates a first selection signal in a first period and a fourth period;
A second selection signal generator that generates a second selection signal in a second period and a third period;
A third selection signal generator that generates a third selection signal during the first period and the third period;
A fourth selection signal generator that generates a fourth selection signal during the second period and the fourth period;
A magneto-electric conversion element having a first terminal pair and a second terminal pair and outputting a signal corresponding to the applied magnetic field;
A signal of a first terminal pair and a signal of a second terminal pair of the magnetoelectric conversion element, the first selection signal and the second selection signal are individually input, and a first period and a fourth period A first switch unit that outputs a signal of the first terminal pair of the magneto-electric conversion element to the second switch and outputs a signal of the second terminal pair of the magneto-electric conversion element during a second period and a third period;
An amplifier for amplifying an output signal of the first switch unit and outputting a signal to an output terminal pair;
A first storage element having both ends connected to an output terminal pair of the amplifier;
The third selection signal is input and connected between one of the output terminal pairs and one terminal of the first storage element, closed during a first period and a third period, and closed during a second period and a third period. A second switch unit that opens during period 4,
A fifth switch connected to one terminal of the second switch unit, receiving a fourth selection signal, opening during the first and third periods, and closing during the second and fourth periods; Department and
A comparator that receives at least one of the voltages at both ends of the second switch through the fifth switch, and outputs a result of comparison with a predetermined value;
A determination circuit that outputs a logical sum signal of an output signal of the comparator in a second period and an output signal of the comparator in a fourth period;
A magnetic field detection device comprising: A signal corresponding to the applied magnetic field output from the magneto-electric conversion element is input and switched so that the polarity is reversed between the first period and the fourth period and between the second period and the third period. A switching step of
An amplification step of amplifying and outputting the signal output in the switching step,
A holding step of holding the voltage output in the amplifying step in a first storage element during a first period and a third period;
An adding step of adding a signal component corresponding to a magnetic field between the voltage output in the amplifying step and a voltage held in the first storage element during a second period and a fourth period;
A comparison step of inputting an addition voltage in the addition step having polarities opposite to each other during a second period and a fourth period, and outputting a result of comparison with a predetermined value;
A determination step of outputting a logical sum signal of an output signal of the comparison step in a second period and an output signal of the comparison step in a fourth period;
A magnetic field detection method comprising: The said 1st switch part is further provided with the signal generator which outputs the signal which determines the said 1st, 2nd, 3rd and 4th period, The Claim 1 or Claim 2 characterized by the above-mentioned. Magnetic field sensor.

Images