Magnetic field sensor device

Abstract

To provide a magnetic field sensor device that can generate an electric signal for use in control of quantity of incident light.SOLUTION: A magnetic field sensor device 1 has: a light emitting unit 10 which emits incident light; a magnetic field sensor 14 to which the incident light is introduced, and which derives return light in accordance with the incident light; a signal generation unit 20 which separates the return light to a S polarization component and P polarization component, and generates a light quantity signal indicative of a quantity of return light on the basis of the S polarization component and P polarization component; and a light quantity control unit 15 which controls an incident light quantity on the basis of the light quantity signal. The signal generation unit 20 has: a first photoelectric conversion element 22 which outputs a first current in accordance with light quantity of S polarization component; a second photoelectric conversion element 23 which outputs a second current in accordance with light quantity of P polarization component; a first current signal generation circuit 25 which generates a first current signal indicative of the first current; a second current signal generation circuit 26 which generates a second current signal indicative of the second current; and a light quantity signal generation circuit 27 which synthesizes the first current signal and second current signal to generate a light quantity signal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a magnetic field sensor device.

Background Art

[0002] In a sensor device that detects a magnetic field by the Faraday effect, a magnetic field sensor device is known that performs feedback control on the amount of light incident on a Faraday element to which a magnetic field is applied, based on the amount of light of the return light from the Faraday element (see, for example, Patent Documents 1 and 2). Patent Documents 1 and 2 enable control of the amount of incident light that reflects noise such as attenuation in an optical path such as an optical fiber that optically connects a light emitting element, a photoelectric conversion element, and a Faraday element, by controlling the amount of incident light based on the amount of return light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, Patent Documents 1 and 2 do not disclose the specific configuration of an electric circuit that converts the return light from the Faraday element into an electric signal used to control the amount of incident light.

[0005] An object of the present invention is to provide a magnetic field sensor device capable of generating an electric signal used to control the amount of incident light.

Means for Solving the Problems

[0006] The magnetic field sensor device according to the present invention includes a light-emitting unit that emits incident light, a magnetic field sensor into which incident light is introduced and which derives reflected light corresponding to the incident light, and in which at least a portion thereof can be placed within a predetermined magnetic field, a signal generation unit that separates the reflected light into an S-polarized component and a P-polarized component, and generates a detection signal corresponding to the magnetic field in which the magnetic field sensor is placed, and a light intensity signal indicating the amount of reflected light, based on the S-polarized component and the P-polarized component, a light branching unit that transmits incident light to the magnetic field sensor and branches the reflected light to the signal generation unit, and an incident light based on the light intensity signal. The signal generation unit includes a light intensity control unit that controls the amount of light, and a first photoelectric conversion element that receives an S-polarized component and outputs a first current corresponding to the amount of light of the received S-polarized component, a second photoelectric conversion element that receives a P-polarized component and outputs a second current corresponding to the amount of light of the received P-polarized component, a first current signal generation circuit that generates a first current signal indicating the first current, a second current signal generation circuit that generates a second current signal indicating the second current, and a light intensity signal generation circuit that synthesizes the first current signal and the second current signal to generate a light intensity signal.

[0007] Furthermore, in the magnetic field sensor device according to the present invention, it is preferable that the first current signal generation circuit includes a first conversion resistor connected in series with the first photoelectric conversion element and a first current signal extraction circuit that extracts a voltage whose absolute value is equal to the first conversion voltage applied to the first conversion resistor as a first current signal, and the second current signal generation circuit includes a second conversion resistor connected in series with the second photoelectric conversion element and a second current signal extraction circuit that extracts a voltage whose absolute value is equal to the second conversion voltage applied to the second conversion resistor as a second current signal.

[0008] Furthermore, in the magnetic field sensor device according to the present invention, it is preferable that the first current signal extraction circuit is a subtraction circuit that subtracts the voltage at the other end of the first conversion resistor from the voltage at one end of the first conversion resistor, and the second current signal extraction circuit is a subtraction circuit that subtracts the voltage at the other end of the second conversion resistor from the voltage at one end of the second conversion resistor.

[0009] Furthermore, in the magnetic field sensor device according to the present invention, it is preferable that the first current signal generation circuit has a first current signal extraction circuit that extracts a current having the same current value as the first current as the first current signal, and the second current signal generation circuit has a second current signal extraction circuit that extracts a current having the same current value as the second current as the second current signal.

[0010] Furthermore, in the magnetic field sensor device according to the present invention, it is preferable that the first current signal extraction circuit is a current mirror circuit that outputs a current having the same current value as the first current as the first current signal, and the second current signal extraction circuit is a current mirror circuit that outputs a current having the same current value as the second current as the second current signal. [Effects of the Invention]

[0011] The magnetic field sensor device according to the present invention can generate an electrical signal used to control the amount of incident light. [Brief explanation of the drawing]

[0012] [Figure 1] Block diagram of a magnetic field sensor device according to the first embodiment. [Figure 2] Figure 1 is a circuit diagram of the signal generation unit. [Figure 3] Block diagram of a magnetic field sensor device according to the second embodiment. [Figure 4] Figure 3 is a circuit diagram of the signal generation unit. [Modes for carrying out the invention]

[0013] The magnetic field sensor device according to the present invention will be described below with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the invention described in the claims and its equivalents.

[0014] (Configuration and function of the magnetic field sensor device according to the first embodiment) Figure 1 is a block diagram showing a magnetic field sensor device according to the first embodiment.

[0015] The magnetic field sensor device 1 is an interference-type optical magnetic field sensor device having a light-emitting unit 10, a circulator 11, a first optical element 12, an optical path unit 13, a magnetic field sensor 14, a light intensity control unit 15, and a signal generation unit 20. The optical path between the light-emitting unit 10, the circulator 11, the first optical element 12, the optical path unit 13, the magnetic field sensor 14, and the signal generation unit 20 is formed by a PANDA (Polarization-maintaining AND Absorption-reducing) fiber 16. In one example, the outer diameter of the PANDA fiber 16 is 125 μm. The optical path between the first optical element 12, the optical path unit 13, the magnetic field sensor 14, and the signal generation unit 20 may be formed by polarization-maintaining optical fibers such as bow-tie fibers and elliptical jacket fibers.

[0016] The light-emitting unit 10 includes a light-emitting element 10a, an isolator 10b, and a polarizer 10c. The light-emitting element 10a is, in one example, a semiconductor laser or a light-emitting diode, and emits incident light that enters the magnetic field sensor 14 via the circulator 11, the first optical element 12, and the optical path unit 13. Specifically, a Fabry-Perot laser, a superluminescent diode, etc., can preferably be used as the light-emitting element 10a. The amount of incident light emitted from the light-emitting element 10a is controlled by the light intensity control unit 15.

[0017] The isolator 10b protects the light-emitting element 10a by allowing light incident from the light-emitting element 10a to pass through to the circulator 11, while preventing light incident from the circulator 11 from passing through to the light-emitting element 10a. In one example, the isolator 10b is a polarization-dependent optical isolator, but it may also be a polarization-independent optical isolator.

[0018] The polarizer 10c is an optical element that converts the light emitted by the light-emitting element 10a into linearly polarized light, and its type is not particularly limited. The first linearly polarized light obtained by the polarizer 10c is incident on the first optical element 12 via the circulator 11.

[0019] The circulator 11 is an optical splitter that transmits the first linearly polarized light emitted from the light-emitting unit 10 to the first optical element 12, and splits the second linearly polarized light emitted from the first optical element 12 to the signal generation unit 20. In one example, the circulator 11 is formed by a Faraday rotator, a half-wave plate, a polarizing beam splitter, and a reflective mirror.

[0020] In one example, the first optical element 12 is a half-wave plate positioned such that its azimuth angle is 22.5 degrees with respect to the polarization plane of the first linearly polarized light incident from the circulator 11. The first optical element 12 rotates the polarization plane of the first linearly polarized light incident from the circulator 11 by 45 degrees and emits the first linearly polarized light into the optical path section 13. The first linearly polarized light whose polarization plane has been rotated by 45 degrees by the first optical element 12 has a first linearly polarized light CW1 which is P-polarized and a second linearly polarized light CCW1 which is S-polarized and orthogonal to the first linearly polarized light CW1.

[0021] Furthermore, the first optical element 12 rotates the polarization plane of the second linearly polarized light, which is incident linearly polarized light from the optical path section 13, by 45 degrees and emits it to the circulator 11.

[0022] The optical path section 13 includes a first beam splitter 13a, a second beam splitter 13b, a first optical path 13c, a second optical path 13d, and a second optical element 13e.

[0023] The first beam splitter 13a emits the first linearly polarized light CW1 into the first optical path 13c and the second linearly polarized light CCW1 into the second optical path 13d. The first beam splitter 13a also receives the third linearly polarized light CW2 from the second optical path 13d and the fourth linearly polarized light CCW2 from the first optical path 13c. The third and fourth linearly polarized light CW2 are mutually orthogonal polarization components of the second linearly polarized light emitted to the first optical element 12.

[0024] The second beam splitter 13b receives the first linearly polarized light CW1 from the first optical path 13c and the second linearly polarized light CCW1 from the second optical path 13d. The second beam splitter 13b also emits the third linearly polarized light CW2 to the second optical path 13d and the fourth linearly polarized light CCW2 to the first optical path 13c.

[0025] The first beam splitter 13a and the second beam splitter 13b separate the incident light into a P-polarized component and an S-polarized component, and then combine the P-polarized component and the S-polarized component and emit them. In one example, the first beam splitter 13a and the second beam splitter 13b are prism-type beam splitters, but they may also be planar beam splitters or wedge-type beam splitters.

[0026] The first optical path 13c leads the first linearly polarized light CW1 introduced from the first beam splitter 13a to the second beam splitter 13b, and also leads the fourth linearly polarized light CCW2 introduced from the second beam splitter 13b to the first beam splitter 13a. The second optical path 13d leads the second linearly polarized light CCW2 introduced from the first beam splitter 13a to the second beam splitter 13b, and also leads the third linearly polarized light CW2 introduced from the second beam splitter 13b to the first beam splitter 13a.

[0027] The first optical path 13c is a PANDA fiber with one end optically connected to the first beam splitter 13a and the other end optically connected to the second beam splitter 13b. The second optical path 13d is a PANDA fiber with one end optically connected to the first beam splitter 13a and the other end optically connected to the second beam splitter 13b. The first optical path 13c and the second optical path 13d may be polarization-maintaining fibers such as bowtie fibers and elliptical jacket fibers. The second optical element 13e is arranged in the second optical path 13d.

[0028] The second optical element 13e includes a first (1 / 4) wave plate 13f, a second (1 / 4) wave plate 13g, and a 45-degree Faraday rotator 13h.

[0029] The first (1 / 4) wave plate 13f is a 1 / 4 wave plate positioned with its optical axis tilted at 45 degrees with respect to the slow axis and fast axis of the PANDA fiber that forms the second optical path 13d. The first (1 / 4) wave plate 13f converts linearly polarized light into circularly polarized light and also converts circularly polarized light into linearly polarized light.

[0030] The second (1 / 4) wave plate 13g is a 1 / 4 wave plate positioned with its optical axis tilted at -45 degrees with respect to the slow axis and fast axis of the PANDA fiber that forms the second optical path 13d. The second (1 / 4) wave plate 13g converts circularly polarized light from the 45-degree Faraday rotator 13h into linearly polarized light, and also converts linearly polarized light into circularly polarized light.

[0031] The 45-degree Faraday rotator 13h is a Faraday rotator that changes the phase of circularly polarized light incident from the first (1 / 4) wave plate 13f and the second (1 / 4) wave plate 13g, respectively.

[0032] The 45-degree Faraday rotator 13h changes the phase of the circularly polarized light incident on the first (1 / 4) wave plate 13f such that the phase of the second linearly polarized light CCW1 emitted from the second (1 / 4) wave plate 13g is shifted by 45 from the phase of the second linearly polarized light CCW1 incident on the first (1 / 4) wave plate 13f. The 45-degree Faraday rotator 13h also changes the phase of the circularly polarized light such that the phase of the third linearly polarized light CW2 emitted from the first (1 / 4) wave plate 13f is shifted by -45 from the phase of the third linearly polarized light CW2 incident on the second (1 / 4) wave plate 13g.

[0033] The magnetic field sensor 14 is positioned at the tip of the PANDA fiber 16 and is optically connected to the second beam splitter 13b via the PANDA fiber 16. The magnetic field sensor 14 includes a quarter-wave plate optically connected to the second beam splitter 13b, a Faraday rotator optically connected to the quarter-wave plate, and a mirror element optically connected to the Faraday rotator. The quarter-wave plate is positioned with its optical axis tilted at 45 degrees with respect to the slow and fast axes of the PANDA fiber 16, and converts the polarization state of the incident linearly polarized light into circularly polarized light, and also converts the polarization state of the reflected light incident from the Faraday rotator as circularly polarized light into linearly polarized light. The Faraday rotator is a granular film having a dielectric and nano-order magnetic particles dispersed in the dielectric in a state of stable phase separation from the dielectric, and changes the phase of the circularly polarized light by a Faraday rotation angle corresponding to the applied magnetic field. The magnetic field sensor 14 receives linearly polarized light emitted from the light-emitting unit 10 as incident light, and also emits reflected light corresponding to the applied magnetic field when the incident light is incident via the optical fiber 16.

[0034] The light intensity control unit 15 receives the light intensity signal V from the signal generation unit 20. L Accordingly, the amount of incident light emitted by the light-emitting element 10a is feedback-controlled by control means such as the ACC (Automactic Current Control) method and the APC (Automotic Power Control) method. Since the control means for the light-emitting element 10a, such as the ACC method and the APC method, are well known, a detailed explanation is omitted here.

[0035] The signal generation unit 20 includes a third beam splitter 21, a first photoelectric conversion element 22, a second photoelectric conversion element 23, a detection signal generation circuit 24, a first current signal generation circuit 25, a second current signal generation circuit 26, and a light intensity signal generation circuit 27. The signal generation unit 20 separates the second linearly polarized light branched by the circulator 11 into an S-polarized component and a P-polarized component, and from the separated S-polarized component and P-polarized component, generates a detection signal Ed corresponding to the magnetic field applied to the magnetic field sensor 14, and a light intensity signal V indicating the amount of reflected light. L Generates.

[0036] The third beam splitter 21 is a polarization beam splitter (PBS) such as a prism type, a planar type, a wedge substrate type, and an optical waveguide type, and splits the second linearly polarized light branched by the circulator 11 into an S-polarization component P S and a P-polarization component P P and separates them.

[0037] Each of the first photoelectric conversion element 22 and the second photoelectric conversion element 23 is, for example, a PIN photodiode in one example. The first photoelectric conversion element 22 receives the S-polarization component P S and the second photoelectric conversion element 23 receives the P-polarization component P P . The first photoelectric conversion element 22 receives the S-polarization component P S and outputs a first current I1 corresponding to the amount of the received S-polarization component P S to the detection signal generation circuit 24 and the first current signal generation circuit 25. The second photoelectric conversion element 23 receives the P-polarization component P P and outputs a second current I2 corresponding to the amount of the received P-polarization component P P to the detection signal generation circuit 24 and the second current signal generation circuit 26.

[0038] FIG. 2 is a circuit diagram of the signal generation unit 20.

[0039] The detection signal generation circuit 24 includes a variable resistor 30, a detection buffer circuit 31, a detection amplifier circuit 32, and a detection subtraction circuit 33. One end of the variable resistor 30 is connected to a first power supply voltage VDD which is, for example, 5V, and the other end is grounded. The detection buffer circuit 31 includes a first detection operational amplifier 31a and a first detection resistor 31b, is connected to a point of the variable resistor 30, selects a voltage between 0V and the power supply voltage VDD, and outputs it to the detection subtraction circuit 33. The non-inverting input terminal of the first detection operational amplifier 31a is selectively connected to a point of the variable resistor 30, and the inverting input terminal of the first detection operational amplifier 31a is connected to the output terminal of the first detection operational amplifier 31a via the first detection resistor 31b.

[0040] The detection amplifier circuit 32 includes a second detection operational amplifier 32a and a second detection resistor 32b, and a differential voltage V corresponding to the difference between the first current I1 and the second current I2. diff The signal is inverted and amplified, and output to the detection subtraction circuit 33. The non-inverting input terminal of the second detection op-amp 32a is grounded, and the inverting input terminal of the second detection op-amp 32a is connected to the anode of the first photoelectric conversion element 22, the cathode of the second photoelectric conversion element 23, and one end of the second detection resistor 32b. The output terminal of the second detection op-amp 32a is connected to the other end of the second detection resistor 32b and the detection subtraction circuit 33, and the differential voltage V diff This is output to the detection / subtraction circuit 33.

[0041] The detection / subtraction circuit 33 includes a third detection operational amplifier 33a, a third detection resistor 33b, a fourth detection resistor 33c, a fifth detection resistor 33d, and a sixth detection resistor 33e. The non-inverting input terminal of the third detection operational amplifier 33a is connected to one end of the third detection resistor 33b and the fourth detection resistor 33c, and the inverting input terminal of the third detection operational amplifier 33a is connected to one end of the fifth detection resistor 33d and the sixth detection resistor 33e. The output terminal of the third detection operational amplifier 33a is connected to the other end of the sixth detection resistor 33e, and outputs a detection signal Ed. The other end of the third detection resistor 33b is connected to one end of the output terminal of the second detection operational amplifier 32a, the other end of the fourth detection resistor 33c is grounded, and the other end of the fifth detection resistor 33d is connected to the output terminal of the first detection operational amplifier 31a.

[0042] The detection / subtraction circuit 33 receives the differential voltage V from the second detection operational amplifier 32a. diff From there, the detection signal Ed is generated by subtracting the voltage of the variable resistor 30 selected by the detection buffer circuit 31, and the generated detection signal Ed is output. By setting the voltage of the variable resistor 30 selected by the detection buffer circuit 31 to match the noise voltage generated in the second detection operational amplifier 32a, the noise voltage generated in the second detection operational amplifier 32a can be compensated for.

[0043] The first current signal generation circuit 25 includes a first reference resistor 40, a first conversion resistor 41, and a first current signal extraction circuit 42, and the S-polarized component P received by the first photoelectric conversion element 22S A first current signal V1 is generated that indicates a first current I1 corresponding to the light intensity. The first reference resistor 40 has a first reference resistance value R, which is 1 kΩ in one example. B1 It has one end connected to the first power supply voltage VDD and the other end connected to one end of the first conversion resistor 41 and the first current signal extraction circuit 42. The first conversion resistor 41 has a first conversion resistance value R, which is 100Ω in one example. C1 It has a terminal that is connected to the cathode of the first photoelectric conversion element 22 and the first current signal extraction circuit 42. The first reference resistor 40 and the first conversion resistor 41 are connected in series with the first photoelectric conversion element 22, and the S polarization component P S A voltage corresponding to the first current I1 flowing through the first photoelectric conversion element 22 in response to receiving light is applied. The first reference resistor 40 has a first reference resistance value R B1 The first reference voltage V is obtained by multiplying the first current I1 by the first reference voltage V. B1 When the first conversion resistor 41 is subjected to the first conversion resistor value R C1 The first converted voltage V is obtained by multiplying the first current I1 by the first current I1. C1 It is applied.

[0044] The first current signal extraction circuit 42 is a subtraction circuit having a first generating operational amplifier 43, a first generating resistor 44, a second generating resistor 45, a third generating resistor 46, and a fourth generating resistor 47. The first current signal extraction circuit 42 applies a first conversion voltage V to the first conversion resistor 41. C1 The inverted voltage is extracted as the first current signal V1. The resistance values ​​of the first generating resistor 44, second generating resistor 45, third generating resistor 46, and fourth generating resistor 47 are 10kΩ in one example. The configuration of the first current signal extraction circuit 42 is the same as that of the detection subtraction circuit 33, so a detailed explanation is omitted here. The first current signal extraction circuit 42 subtracts the voltage at the other end of the first conversion resistor 41 from the voltage at one end of the first conversion resistor 41, thereby obtaining the first conversion voltage V applied to the first conversion resistor 41. C1 The inverted voltage is extracted as the first current signal V1.

[0045] The second current signal generation circuit 26 includes a second reference resistor 50, a second conversion resistor 51, and a second current signal extraction circuit 52, and the second photoelectric conversion element 23 receives the P-polarized component P PA second current signal V2 is generated that indicates a second current I2 corresponding to the light intensity. The second reference resistor 50 is equal to the first reference resistance value R B1 The second reference resistance value R is equal to B2 The second reference resistor 50 has one end connected to the second power supply voltage VSS and the other end connected to one end of the second conversion resistor 51 and the second current signal extraction circuit 52. The second power supply voltage VSS to which one end of the second reference resistor 50 is connected is -5V in one example. The second conversion resistor 51 has a first conversion resistance value R C1 The second conversion resistance value R is equal to this value. C2 It has a second end connected to the anode of the second photoelectric conversion element 23 and the second current signal extraction circuit 52. The second reference resistor 50 and the second conversion resistor 51 are connected in series with the second photoelectric conversion element 23, and the P polarization component P P A voltage corresponding to the second current I2 flowing through the second photoelectric conversion element 23 in response to receiving light is applied. The second reference resistor 50 has a second reference resistance value R B2 The second reference voltage V is obtained by multiplying the second current I2 by the second current I2. B2 When the voltage is applied, the second conversion resistor 51 has a second conversion resistance value R C2 The second converted voltage V is obtained by multiplying the second current I2 by the second current I2. C2 It is applied.

[0046] The second current signal extraction circuit 52 is a subtraction circuit having a second generating operational amplifier 53, a fifth generating resistor 54, a sixth generating resistor 55, a seventh generating resistor 56, and an eighth generating resistor 57, and the second conversion voltage V applied to the second conversion resistor 51 C2 This is extracted as the second current signal V2. The resistance values ​​of the fifth generating resistor 54, sixth generating resistor 55, seventh generating resistor 56, and eighth generating resistor 57 are 10kΩ in one example. The configuration of the second current signal extraction circuit 52 is the same as that of the detection subtraction circuit 33, so a detailed explanation is omitted here. The second current signal extraction circuit 52 subtracts the voltage at the other end of the second conversion resistor 51 from the voltage at one end of the second conversion resistor 51, thereby obtaining the second conversion voltage V applied to the second conversion resistor 51. C2 This is extracted as the second current signal V2.

[0047] The light intensity signal generation circuit 27 has a light intensity subtraction circuit 61 and a light intensity buffer 62, and combines the first current signal V1 and the second current signal V2 to generate a light intensity signal VL A light intensity signal V is generated. L The output is sent to the light intensity control unit 15.

[0048] The light intensity subtraction circuit 61 is a subtraction circuit having a first light intensity operational amplifier 63, a first light intensity resistor 64, a second light intensity resistor 65, a third light intensity resistor 66, and a fourth light intensity resistor 67, and subtracts the first current signal V1 from the second current signal V2 to obtain the light intensity signal V L This generates the following. The resistance values ​​of the first light intensity resistor 64, the second light intensity resistor 65, the third light intensity resistor 66, and the fourth light intensity resistor 67 are 1 kΩ in one example. The configuration of the light intensity subtraction circuit 61 is the same as that of the detection subtraction circuit 33, so a detailed explanation is omitted here.

[0049] The light intensity subtraction circuit 61 extracts the second current signal V2 in the second current signal extraction circuit 52, and the second converted voltage V C2 From there, the first converted voltage V extracted as the first current signal V1 in the first current signal extraction circuit 42 C1 The inverted voltage is subtracted. The light intensity subtraction circuit 61 subtracts the second converted voltage V C2 From the first conversion voltage V C1 By subtracting the inverted voltage, the first converted voltage V is obtained. C1 and the second conversion voltage V C2 Adding these together, we get the light intensity signal V L Generates.

[0050] The light intensity buffer 62 has a second light intensity operational amplifier 68 and receives the light intensity signal V from the light intensity subtraction circuit 61. L The light intensity control unit 15 outputs the light intensity signal V. L In response to the input, the amount of incident light emitted by the light-emitting element 10a is feedback-controlled.

[0051] (Effects of the magnetic field sensor device according to the first embodiment) The magnetic field sensor device 1 combines the first current signal V1 and the second current signal V2, which represent the first current I1 and second current I2 output from the first photoelectric conversion element 22 and the second photoelectric conversion element 23, respectively, to generate a light intensity signal V L Since it generates the light intensity signal V with a simple configurationL It can generate.

[0052] The magnetic field sensor device 1 applies a first conversion voltage V to the first conversion resistor 41 by the first current signal extraction circuit 42, which is a subtraction circuit. C1 The inverted voltage is extracted as the first current signal V1. The magnetic field sensor device 1 also extracts the second converted voltage V applied to the second conversion resistor 51 by the second current signal extraction circuit 52, which is a subtraction circuit. C2 The light intensity signal V is extracted as a second current signal. The magnetic field sensor device 1 forms the first current signal extraction circuit 42 and the second current signal extraction circuit 52 using subtraction circuits that can be implemented with a simple circuit configuration, so that the light intensity signal V can be extracted with a simple configuration. L It can generate.

[0053] (Configuration and function of the magnetic field sensor device according to the second embodiment) Figure 3 is a block diagram showing a magnetic field sensor device according to the second embodiment.

[0054] Magnetic field sensor device 2 differs from magnetic field sensor device 1 in that it has a signal generation unit 70 instead of a signal generation unit 20. Signal generation unit 70 differs from signal generation unit 20 in that it has a first current signal generation circuit 71 and a second current signal generation circuit 72 instead of a first current signal generation circuit 25 and a second current signal generation circuit 26. The configuration and function of the components of magnetic field sensor device 2 other than the first current signal generation circuit 71 and the second current signal generation circuit 72 are the same as the configuration and function of the components of magnetic field sensor device 1 which are given the same reference numerals, so a detailed explanation is omitted here.

[0055] Figure 4 is a circuit diagram of the signal generation unit 70.

[0056] The first current signal generation circuit 71 has a first reference resistor 73 and a first current signal extraction circuit 74, and the S-polarized component P received by the first photoelectric conversion element 22 S A first current signal I that indicates a first current I1 corresponding to the light intensity. O1 This generates the first reference resistor 73, which in one example is a first reference resistance value R of 1kΩ. B1It has one end connected to the first current signal extraction circuit 74 and the other end connected to the anode of the first photoelectric conversion element 22.

[0057] The first current signal extraction circuit 74 has a first transistor 75 and a second transistor 76 which are pMOSFETs, and the first current signal I O1 The first transistor 75 and the second transistor 76, and the drain of the first transistor 75, are connected to one end of the first reference resistor 73, and the sources of the first transistor 75 and the second transistor 76 are connected to the first power supply voltage VDD. The drain of the second transistor 76 is connected to one end of the third light intensity resistor 66. The first transistor 75 and the second transistor 76 form a current mirror circuit. S polarization component P S In response to receiving light, a first current I1 flows through the first photoelectric conversion element 22, and in response, the first current I1 flows as the drain current of the first transistor 75. When the first current I1 flows as the drain current of the first transistor 75, the first current signal I, which has the same amount of current as the first current I1, O1 This current flows as the drain current of the second transistor 76.

[0058] The second current signal generation circuit 72 has a second reference resistor 77 and a second current signal extraction circuit 78, and the second photoelectric conversion element 23 receives the P-polarized component P P The second current signal I indicates the second current I2 corresponding to the light intensity. O2 This generates the second reference resistor 77, which is equal to the first reference resistor value R. B1 The second reference resistance value R is equal to B2 It has one end connected to the second photoelectric conversion element 23 and the other end connected to the second current signal extraction circuit 78.

[0059] The second current signal extraction circuit 78 has a third transistor 79 and a fourth transistor 80 which are nMOSFETs, and the second current signal I O2The gates of the third transistor 79 and the fourth transistor 80, and the drain of the third transistor 79, are connected to the other end of the second reference resistor 77, and the sources of the third transistor 79 and the fourth transistor 80 are connected to the second power supply voltage VSS. The drain of the fourth transistor 80 is connected to one end of the first light intensity resistor 64. The third transistor 79 and the fourth transistor 80, like the first transistor 75 and the second transistor 76, form a current mirror circuit. P polarization component P P In response to receiving light, a second current I2 flows through the second photoelectric conversion element 23, and in response, the second current I2 flows as the drain current of the third transistor 79. When the second current I2 flows as the drain current of the third transistor 79, a second current signal I, which has the same amount of current as the second current I2 and flows in the opposite direction to the first current I1, is generated. O2 This current flows as the drain current of the fourth transistor 80.

[0060] The light intensity subtraction circuit 61 receives a first current signal I, which has the same current value as the first current I1. O1 Therefore, the second current signal I has the same current value as the second current I2 and flows in the opposite direction to the first current I1. O2 The light intensity subtraction circuit 61 subtracts the first current signal I. O1 The second current signal I flows in the opposite direction to the first current I1. O2 By subtracting this, the first current signal I O1 and the second current signal I O2 Adding these together, we get the light intensity signal V L Generates.

[0061] (Effects of the magnetic field sensor device according to the second embodiment) The magnetic field sensor device 2 uses a first current signal extraction circuit 74, which is a current mirror circuit, to extract a first current signal I that is the same as the first current I1. O1 The magnetic field sensor device 1 extracts the second current signal I, which has the same current amount as the second current I2 and flows in the opposite direction to the first current I1, through the second current signal extraction circuit 78, which is a current mirror circuit. O2The magnetic field sensor device 1 forms the first current signal extraction circuit 42 and the second current signal extraction circuit 52 using current mirror circuits that can be realized with a simple circuit configuration, and thus extracts the light intensity signal V L It can generate.

[0062] (Modified example of a magnetic field sensor device according to the embodiment) The magnetic field sensor devices 1 and 2 are interferometric optical magnetic field sensor devices, but the magnetic field sensor in the embodiment may be a magnetic field sensor other than an interferometric optical magnetic field sensor device.

[0063] Furthermore, in magnetic field sensor devices 1 and 2, the light intensity signal generation circuit 27 has a light intensity subtraction circuit 61 that performs subtraction processing. However, in the magnetic field sensor according to this embodiment, the light intensity signal generation circuit may also have an addition circuit that adds the first current signal and the second current signal.

[0064] Furthermore, in the magnetic field sensor device 2, the first current signal extraction circuit 74 and the second current signal extraction circuit 78 are formed by MOSFETs. However, in the magnetic field sensor according to this embodiment, the first current signal extraction circuit and the second current signal extraction circuit may be formed by bipolar transistors.

[0065] Furthermore, in the magnetic field sensor device 1, the first current signal extraction circuit 42 and the second current signal extraction circuit 52 are formed as subtraction circuits, but in the magnetic field sensor according to this embodiment, the first current signal extraction circuit and the second current signal extraction circuit may be formed as addition circuits.

[0066] Furthermore, in the magnetic field sensor device 2, the first current signal extraction circuit 74 and the second current signal extraction circuit 78 are formed by MOSFETs. However, in the magnetic field sensor according to this embodiment, the first current signal extraction circuit and the second current signal extraction circuit may be formed by bipolar transistors. [Explanation of symbols]

[0067] 1, 2 Magnetic field sensor device 10 Light-emitting part 11. Circulator 12 1 / 2 wave plate 13 Optical path section 14 Magnetic field sensor 15 Light intensity control unit 20, 70 Signal generation unit 21. Third Beam Splitter 22 First photoelectric element 23. Second photoelectric element 24 Detection signal generation circuit 25, 71 1st current signal generation circuit 26, 72 Second current signal generation circuit 27 Light amount signal generation circuit

Claims

1. A light-emitting part that emits incident light, A magnetic field sensor into which the incident light is introduced, which derives a reflected light corresponding to the incident light, and which can place at least a portion of the reflected light within a predetermined magnetic field, A signal generation unit separates the reflected light into an S-polarized component and a P-polarized component, and generates a detection signal corresponding to the magnetic field where the magnetic field sensor is located, and a light intensity signal indicating the amount of light in the reflected light, based on the S-polarized component and the P-polarized component. An optical branching unit that transmits the incident light to the magnetic field sensor and branches the reflected light to the signal generation unit, It comprises a light intensity control unit that controls the amount of incident light based on the light intensity signal, The signal generation unit, A first photoelectric conversion element that receives the S-polarized component and outputs a first current corresponding to the amount of light of the received S-polarized component, A second photoelectric conversion element that receives the P-polarized light component and outputs a second current corresponding to the amount of light of the received P-polarized light component, A first current signal generation circuit that generates a first current signal indicating the first current, A second current signal generation circuit that generates a second current signal indicating the second current, A light intensity signal generation circuit that generates the light intensity signal by combining a first current signal corresponding to the light intensity of the S-polarization component and a second current signal corresponding to the light intensity of the P-polarization component, It has, The magnetic field sensor device is characterized in that the light intensity control unit controls the amount of incident light based on a light intensity signal obtained by combining a first current signal corresponding to the amount of light of the S-polarization component and a second current signal corresponding to the amount of light of the P-polarization component.

2. The first current signal generation circuit includes a first conversion resistor connected in series with the first photoelectric conversion element, and a first current signal extraction circuit that extracts a voltage whose absolute value is equal to the first conversion voltage applied to the first conversion resistor as the first current signal. The magnetic field sensor device according to claim 1, wherein the second current signal generation circuit includes a second conversion resistor connected in series with the second photoelectric conversion element, and a second current signal extraction circuit that extracts a voltage equal in absolute value to the second conversion voltage applied to the second conversion resistor as the second current signal.

3. The first current signal extraction circuit is a subtraction circuit that subtracts the voltage at the other end of the first conversion resistor from the voltage at one end of the first conversion resistor. The magnetic field sensor device according to claim 2, wherein the second current signal extraction circuit is a subtraction circuit that subtracts the voltage at the other end of the second conversion resistor from the voltage at one end of the second conversion resistor.

4. The first current signal generation circuit includes a first current signal extraction circuit that extracts a current having the same current value as the first current as the first current signal. The magnetic field sensor device according to claim 1, wherein the second current signal generation circuit has a second current signal extraction circuit that extracts a current having the same current value as the second current as the second current signal.

5. The first current signal extraction circuit is a current mirror circuit that outputs a current having the same current value as the first current as the first current signal. The magnetic field sensor device according to claim 4, wherein the second current signal extraction circuit is a current mirror circuit that outputs a current having the same current value as the second current as the second current signal.

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