Power supply circuit, encoder, and power supply circuit control method

Abstract

To provide a power source circuit and an encoder each of which comprises a power generation element and can highly efficiently utilize power supplied from the power source circuit, and a method of controlling a power source circuit.SOLUTION: A power source circuit is provided, comprising: a power generation element; a first power storage element that has a first terminal connected to a common potential, and a second terminal connected to the power generation element; a rectifier that has a positive terminal connected to the second terminal, and a negative terminal; a second power storage element that has a third terminal connected to the common potential, and a fourth terminal connected to the negative terminal; a comparison element that has a first input terminal connected to the second terminal, and a second input terminal connected to the negative terminal, and that outputs comparison result from an output terminal on the basis of a potential difference between a first potential at the first input terminal and a second potential at the second input terminal; a stabilization power source circuit; and a switch element that connects or disconnects between the second terminal and the stabilization power source circuit on the basis of the output of the output terminal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power supply circuit, an encoder, and a method for controlling a power supply circuit. [Background technology]

[0002] Patent Document 1 discloses a power generation detection device that does not require a power source or battery, and a rotation counter that uses this power generation detection device to count and record the number of rotations. Patent Document 1 also discloses that when the output voltage of the power-on reset circuit of the power generation detection device exceeds a threshold voltage, the sequencer is started and the detection result of the voltage detection circuit is recorded in a non-volatile logic circuit.

[0003] Patent Document 2 discloses a power generating device capable of generating a predetermined DC voltage even when the rotation speed of a rotating member fluctuates greatly. Patent Document 2 discloses that the power generating device includes a plurality of voltage conversion units capable of converting an input voltage supplied from a rectifier circuit into a voltage of a predetermined value and outputting the voltage, and an output circuit unit that selectively outputs one of the output voltages of the plurality of voltage conversion units.

[0004] Patent Document 3 discloses a rotation signal generator and a rotation detection system that do not require power wiring or battery replacement. Patent Document 3 discloses that the rotation signal generator includes rectifying means that rectifies AC power output from a power generation unit to make it a pulsating current, and charging means that converts the pulsating current obtained by the rectifying means into a DC current and charges the DC current, and that the power once charged in the charging means is supplied to a downstream transmitting unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6321918 [Patent Document 2] Japanese Patent Publication No. 2020-031488 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-161638 Summary of the Invention [Problem to be solved by the invention]

[0006] When the power generated by the power generation element is first charged into a storage element and then supplied to a power supply circuit, if the energy is discharged to the power supply circuit when the charge stored in the storage element is insufficient, there may be a shortage of energy midway through depending on the load conditions. When there is a shortage of energy, the power supply voltage output from the power supply circuit may drop.

[0007] Furthermore, when the output from the power generating element fluctuates, there are cases where control using a fixed threshold value, as disclosed in Patent Document 1, for example, cannot provide appropriate control.

[0008] An object of the present disclosure is to provide a power supply circuit, an encoder, and a method for controlling the power supply circuit that can utilize power supplied from a power generating element with high efficiency. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, there is provided a power generating device including a power generating element that converts external energy into an electric pulse, a first storage element that has a first terminal connected to a common potential and a second terminal connected to the power generating element and stores electricity between the first terminal and the second terminal, a rectifier that has a positive terminal connected to the second terminal and a negative terminal and that passes current from the positive terminal to the negative terminal, a third terminal connected to the common potential, a fourth terminal connected to the negative terminal, a second storage element that stores electricity between the third terminal and the fourth terminal, and a first storage element that connects to the second terminal. The present invention provides a power supply circuit comprising: an input terminal and a second input terminal connected to the negative terminal; a comparison element that outputs from an output terminal based on a potential difference between a first potential at the first input terminal and a second potential at the second input terminal; a stabilized power supply circuit; and a switch element that connects or disconnects the second terminal and the stabilized power supply circuit based on the output of the output terminal, wherein when the first potential becomes lower than the second potential after the electrical pulse is generated, the switch element connects the second terminal and the stabilized power supply circuit. [Effects of the Invention]

[0010] According to the power supply circuit, encoder, and power supply circuit control method disclosed herein, it is possible to use the power supplied from the power generating element with high efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a servo motor system using an encoder according to this embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a servo motor using the encoder according to this embodiment. [Figure 3] FIG. 3 is a diagram illustrating the circuit configuration of the encoder according to this embodiment. [Figure 4] FIG. 4 is a diagram illustrating the circuit configuration of the encoder according to this embodiment. [Figure 5] FIG. 5 is a diagram illustrating the processing of the encoder according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that, in the description of the specification and drawings relating to each embodiment, components having substantially the same or corresponding functional configurations may be designated by the same reference numerals, and redundant description may be omitted. Furthermore, to facilitate understanding, the scale of each part in the drawings may differ from the actual scale.

[0013] <Servo motor system 1> First, a servo motor system 1 using an encoder 12 according to this embodiment will be described. Fig. 1 is a diagram illustrating a servo motor system 1 using an encoder 12 according to this embodiment.

[0014] The servo motor system 1 includes a servo motor 10 and a servo controller 20. The servo controller 20 acquires at least one of position information and rotation information of the rotation shaft 11a from the servo motor 10. The servo controller 20 controls the servo motor 10 using at least one of the acquired position information and rotation information.

[0015] The servo motor 10 includes a motor 11 and an encoder 12. The motor 11 is connected to a servo controller 20 via a wire L1. The encoder 12 is connected to the servo controller 20 via a wire L2.

[0016] The motor 11 rotates the rotary shaft 11a in the direction of the arrow AR based on a command from the servo controller 20. Specifically, the motor 11 rotates the rotary shaft 11a based on power supplied from the servo controller 20. The servo controller 20 controls the motor 11 by supplying controlled power from a wiring L1. The motor 11 is, for example, an alternating current (AC) motor, a direct current (DC) motor, or the like.

[0017] The encoder 12 detects fluctuations in the magnetic field to detect at least one of position information and rotation information of an object such as the rotating shaft 11a of the motor 11. The encoder 12 also outputs the detected position information and / or rotation information to the servo controller 20 via the wiring L2. The position information of the rotating shaft 11a is, for example, the angle of the rotation direction of the rotating shaft 11a. The rotation information of the rotating shaft 11a is, for example, the rotation speed of the rotating shaft 11a.

[0018] <Servo motor 10> Next, the configuration of the servo motor 10 using the encoder 12 according to this embodiment will be described. Figure 2 is a diagram illustrating the configuration of the servo motor 10 using the encoder 12 according to this embodiment. Note that lines with arrows indicate the flow of power or current supply.

[0019] [Motor 11] The motor 11 includes a disk 11d provided on the rotary shaft 11a facing the encoder 12, and a magnet 11m provided on the disk 11d. In addition to the rotary shaft 11a, the disk 11d, and the magnet 11m, the motor 11 also includes well-known elements such as bearings that support the rotary shaft 11a, windings that form a stator for rotating the rotary shaft 11a, an iron core, and permanent magnets that form a rotor, but a description of these elements will be omitted here.

[0020] Disk 11d is fixed to rotating shaft 11a. Disk 11d rotates together with rotating shaft 11a as rotating shaft 11a rotates in the direction of arrow AR. Magnet 11m is fixed to the surface of disk 11d on the encoder 12 side.

[0021] The magnet 11m is a permanent magnet made of neodymium or the like. The magnet 11m is provided so as to have an N pole and an S pole in a direction parallel to the surface of the disk 11d. When the magnet 11m rotates together with the disk 11d, the magnetic field on the encoder 12 side changes.

[0022] [Encoder 12] The encoder 12 will now be described. By describing the encoder 12, the power supply circuit 12d included in the encoder 12 and a method for controlling the power supply circuit 12d will be described. The encoder 12 detects at least one of position information and rotation information of the rotating shaft 11a based on the magnetic field that changes with the rotation of the magnet 11m. The encoder 12 also generates the power required to operate the encoder 12 based on the magnetic field that changes with the rotation of the magnet 11m.

[0023] The encoder 12 includes a power generating element 12g, a rectifier circuit 12a, a switching circuit 12b, a stabilized power supply circuit 12c, a drive circuit 12e, a Hall element 12h, a signal processing circuit 12f, and a control circuit 12p. The power generating element 12g, rectifier circuit 12a, switching circuit 12b, and stabilized power supply circuit 12c are collectively referred to as a power supply circuit 12d. The drive circuit 12e, Hall element 12h, and signal processing circuit 12f are collectively referred to as an analog processing circuit 12m.

[0024] The encoder 12 includes a power generating element 12g that generates power using a change in magnetic flux due to movement, and a Hall element 12h that measures the magnetic field. The power generating element 12g and the Hall element 12h are each provided on the motor 11 side of the encoder 12 so as to be easily affected by the magnetic field generated by the magnet 11m.

[0025] [Power generating element 12g] The power generating element 12g is an element that generates power by converting external energy into an electric pulse. The power generating element 12g is, for example, a Wiegand wire that is an energy harvest generator (EHG).

[0026] Wiegand wire generates an electric pulse near the zero point where the external magnetic field reverses, regardless of the rate of change of the external magnetic flux. Therefore, Wiegand wire generates a constant power regardless of the rotation speed of the rotating shaft 11a. Wiegand wire generates a stable electric pulse (voltage pulse) even with a gradual change in magnetic flux due to slow rotation (movement). Wiegand wire generates an electric pulse when the magnetic field reverses.

[0027] By using an environmental power generator in the power generating element 12g, the encoder 12 does not require a battery or external power source. In other words, the encoder 12 is a battery-less encoder. Wiegand wire generates a constant amount of power regardless of the rotation speed of the rotating shaft 11a, and a stable power generation waveform can be obtained even at low rotation speeds in particular, so it is suitable for use as the power generating element 12g of the battery-less encoder 12.

[0028] The power generating element 12g is not limited to a Wiegand wire, and may be, for example, a coil or the like that generates power from changes in a magnetic field.

[0029] [Hall element 12h] The Hall element 12h detects the magnetic field that crosses the semiconductor element through which the drive current flows. In the encoder 12, the Hall element 12h mainly detects the magnetic field generated by the magnet 11m. The Hall element 12h is made of a semiconductor element such as indium antimonide (InSb) or gallium arsenide (GaAs). The Hall element 12h outputs a voltage proportional to the drive current and the magnetic flux density that crosses the drive current.

[0030] The Hall element 12h outputs a detection signal of the magnetic field to the signal processing circuit 12f. A constant current Idr is supplied to the Hall element 12h from the drive circuit 12e.

[0031] The Hall element 12h is supplied with a current (constant current Idr) that is obtained by rectifying the power generated by the power generating element 12g in the rectifier circuit 12a and then making it constant in the drive circuit 12e.

[0032] Although the encoder 12 includes one Hall element, the number of Hall elements is not limited to one. The encoder 12 may include multiple Hall elements. Furthermore, the measurement of the magnetic field is not limited to the Hall element as long as it is an element capable of detecting magnetism (magnetic detection element). For example, a magnetoresistance effect element or the like may be used instead of the Hall element 12h.

[0033] The circuit configuration of the encoder 12 will be described with reference to Fig. 3. Fig. 3 is a diagram illustrating the circuit configuration of the encoder 12 according to this embodiment.

[0034] [Rectifier circuit 12a] The rectifier circuit 12a rectifies the power generated by the power generating element 12g to generate a positive voltage. The rectifier circuit 12a includes a full-wave rectifier circuit 12a1 and a first capacitor 12a2.

[0035] The full-wave rectifier circuit 12a1 rectifies the positive and negative pulses of the voltage Vgn generated by the power generating element 12g into positive pulses. The full-wave rectifier circuit 12a1 is a so-called diode bridge circuit. For example, when the power generating element 12g is a Wiegand wire, the power generating element 12g generates positive and negative pulses. The full-wave rectifier circuit 12a1 converts the positive and negative pulses generated by the power generating element 12g into positive pulses.

[0036] The first capacitor 12a2 has a first terminal T1 and a second terminal T2. The first terminal T1 is connected to a common potential. The second terminal T2 is connected to the power generating element 12g via the full-wave rectifier circuit 12a1. The first capacitor 12a2 stores the power generated by the power generating element 12g.

[0037] First capacitor 12a2 smoothes the positive pulse generated by full-wave rectifier circuit 12a1. First capacitor 12a2 is provided between the output terminal of full-wave rectifier circuit 12a1 and a common potential. As the positive pulse is smoothed by first capacitor 12a2, a smoothed voltage Vrc is output from rectifier circuit 12a.

[0038] [Switching circuit 12b] The switching circuit 12b connects or disconnects the rectifier circuit 12a and the stabilized power supply circuit 12c. In other words, the switching circuit 12b connects or disconnects the rectifier circuit 12a and the stabilized power supply circuit 12c.

[0039] Before the power generating element 12g generates an electric pulse, the switching circuit 12b opens the connection between the rectifier circuit 12a and the stabilized power supply circuit 12c. That is, before the power generating element 12g generates an electric pulse, the switching circuit 12b disconnects the rectifier circuit 12a from the stabilized power supply circuit 12c. Then, after the power generating element 12g generates an electric pulse and the voltage of the electric pulse rectified by the rectifier circuit 12a reaches a maximum, the switching circuit 12b closes the connection between the rectifier circuit 12a and the stabilized power supply circuit 12c. That is, after the power generating element 12g generates an electric pulse and the voltage of the electric pulse rectified by the rectifier circuit 12a reaches a maximum, the switching circuit 12b connects the rectifier circuit 12a to the stabilized power supply circuit 12c.

[0040] A specific configuration of the switching circuit 12b will be described with reference to Fig. 4. Fig. 4 is a diagram illustrating the circuit configuration of the encoder 12 according to this embodiment, particularly the switching circuit 12b.

[0041] The switching circuit 12b includes a second capacitor 12b1, a rectifier 12b2, a comparison element 12b5, and a switch element 12b6. The rectifier 12b2 includes a first rectifier element 12b3 and a second rectifier element 12b4.

[0042] Second capacitor 12b1 stores a portion of the power of the electric pulse generated by power generating element 12g. Second capacitor 12b1 is connected to rectifier circuit 12a via rectifier 12b2.

[0043] The second capacitor 12b1 has a third terminal T3 and a fourth terminal T4. The third terminal T3 is connected to a common potential. The fourth terminal T4 is connected to the second terminal T2 of the first capacitor 12a2 via the rectifier 12b2. The second capacitor 12b1 stores a portion of the power generated by the power generating element 12g. It is desirable that the storage capacity of the first capacitor 12a2 be larger than that of the second capacitor 12b1.

[0044] Rectifier 12b2 allows current to flow in one direction and prevents current from flowing in the other direction. Rectifier 12b2 has a positive terminal Tp and a negative terminal Tm. Rectifier 12b2 includes first rectifying element 12b3 and second rectifying element 12b4 between the positive terminal Tp and the negative terminal Tm. First rectifying element 12b3 and second rectifying element 12b4 are connected in series between the positive terminal Tp and the negative terminal Tm, in other words, between the second terminal T2 of first capacitor 12a2 and the fourth terminal T4 of second capacitor 12b1.

[0045] Each of first rectifier 12b3 and second rectifier 12b4 is, for example, a diode. When a current flows through rectifier 12b2, a voltage drops across each of first rectifier 12b3 and second rectifier 12b4. Therefore, when a current flows through rectifier 12b2, voltage Vt, which is the voltage across fourth terminal T4 of second capacitor 12b1, becomes lower than voltage Vrc, which is the voltage across second terminal T2 of first capacitor 12a2.

[0046] In the above example, a diode is used as the rectifying element, but the rectifying element is not limited to a diode. For example, a transistor such as a diode-connected metal-oxide-semiconductor field-effect transistor (MOSFET) may be used instead of the diode as the rectifying element.

[0047] The comparing element 12b5 compares the potential difference between the voltage Vrc at the second terminal T2 of the first capacitor 12a2 and the voltage Vt at the fourth terminal T4 of the second capacitor 12b1, and outputs the comparison result. The comparing element 12b5 is a so-called comparator.

[0048] The positive terminal (first input terminal Ip1) of the comparison element 12b5 is connected to the second terminal T2 of the first capacitor 12a2. The negative terminal (second input terminal Ip2) of the comparison element 12b5 is connected to the fourth terminal T4 of the second capacitor 12b1. The output terminal Op1 of the comparison element 12b5 is connected to the switch element 12b6. The positive power supply terminal Pp1 of the comparison element 12b5 is connected to the second terminal T2 of the first capacitor 12a2. The negative power supply terminal Pm1 of the comparison element 12b5 is connected to a common potential.

[0049] Switch element 12b6 opens and closes the connection between rectifier circuit 12a and stabilized power supply circuit 12c based on the output of comparator element 12b5. Switch element 12b6 is, for example, an analog switch. When power is required for switch element 12b6, the power supply terminal of switch element 12b6 is connected to second terminal T2 of first capacitor 12a2 to input voltage Vrc.

[0050] It is desirable that the response speed of the comparison element 12b5 and the switch element 12b6 be faster than the rise time of the electric pulse supplied from the power generating element 12g.

[0051] [Stabilized power supply circuit 12c] The stabilized power supply circuit 12c converts the voltage output from the rectifier circuit 12a into a substantially constant voltage and outputs the voltage. The stabilized power supply circuit 12c includes a regulator 12c1. The regulator 12c1 is, for example, an LDO (Low Dropout) regulator.

[0052] The stabilized power supply circuit 12c outputs a substantially constant voltage Vdd when a voltage of a predetermined magnitude is input.

[0053] [Driver circuit 12e] The drive circuit 12e is a so-called constant current circuit that supplies a constant current Idr to the Hall element 12h. The drive circuit 12e operates as a constant current source. The encoder 12 drives the Hall element 12h with the constant current Idr. The drive circuit 12e supplies drive power to the Hall element 12h so that a constant current flows through the Hall element 12h as a drive current.

[0054] The drive circuit 12e is driven by the voltage Vdd supplied from the stabilized power supply circuit 12c.

[0055] [Signal processing circuit 12f] The signal processing circuit 12f processes the detection signal from the Hall element 12h to detect the direction of the magnetic field of the magnet 11m. The signal processing circuit 12f will be described with reference to FIG.

[0056] The signal processing circuit 12f includes a differential amplifier 12f1 and a comparator 12f2.

[0057] (Differential amplifier 12f1) The differential amplifier 12f1 amplifies the potential difference between the voltage Vh+ and the voltage Vh− output from the Hall element 12h to generate a voltage Vd, and outputs the amplified voltage Vd to the comparator 12f2. The differential amplifier 12f1 is supplied with power of the voltage Vdd from the stabilized power supply circuit 12c.

[0058] (Comparator 12f2) The comparator 12f2 compares the voltage Vd output from the differential amplifier 12f1 with a reference potential (reference potential Vref) and outputs the comparison result to the control circuit 12p. The comparator 12f2 is a so-called comparator. The comparator 12f2 includes a differential amplifier 12f2a and resistors 12f2b, 12f2c, and 12f2d. The differential amplifier 12f2a receives power of voltage Vdd from the stabilized power supply circuit 12c. The differential amplifier 12f2a compares the voltage Vd output from the differential amplifier 12f1 with a reference potential Vref generated by dividing the voltage Vdd using resistors 12f2c and 12f2d, and outputs the comparison result to the control circuit 12p as a magnetic pole signal Smg, which is a voltage signal. The resistor 12f2b is a feedback resistor.

[0059] [Control circuit 12p] Based on the input from the signal processing circuit 12f, the control circuit 12p calculates at least one of position information and rotation information, such as the rotation position and rotation speed, of the rotating shaft 11a of the motor 11. The control circuit 12p also records at least one of the detected position information and rotation information of the rotating shaft 11a of the motor 11, and transmits it to an external control system, for example, the servo controller 20.

[0060] The control circuit 12p is, for example, a microcomputer, an ASIC (application specific integrated circuit), etc. The control circuit 12p may also be, for example, an FPGA (field-programmable gate array), a PLD (programmable logic device), etc. Furthermore, the control circuit 12p may include a nonvolatile memory such as a ferroelectric memory. The control circuit 12p may also be connected to an externally provided nonvolatile memory such as a ferroelectric memory.

[0061] The control circuit 12p includes at least a terminal PWR and a terminal SIG.

[0062] The terminal PWR of the control circuit 12p is a terminal to which positive power is supplied. The terminal PWR is supplied with power of voltage Vdd from the stabilized power supply circuit 12c. The control circuit 12p operates when power is supplied to the terminal PWR.

[0063] A terminal SIG of the control circuit 12p is a terminal to which a signal is input from the outside. The terminal SIG is connected to the signal processing circuit 12f. A magnetic pole signal Smg, which is the detection result detected by the signal processing circuit 12f, is input from the terminal SIG. The magnetic pole signal Smg is a signal that indicates the direction of the magnetic field detected by the Hall element 12h.

[0064] <Encoder 12 Operation> The operation of the encoder 12 will now be described. FIG. 5 is a diagram illustrating the processing of the encoder 12 according to this embodiment. FIG. 5(a) shows the output voltage of the power generating element 12g, the voltage Vrc at the second terminal T2 of the first capacitor 12a2, and the voltage Vt at the fourth terminal T4 of the second capacitor 12b1. FIG. 5(b) shows the voltage at the output terminal Op1 of the comparison element 12b5. FIG. 5(c) shows the voltage Vdd output from the stabilized power supply circuit 12c.

[0065] In Figures 5(a), 5(b), and 5(c), the vertical axis represents voltage and the horizontal axis represents time. The horizontal axes in Figures 5(a), 5(b), and 5(c) are arranged so that the same point on the horizontal axis represents the same time.

[0066] When the rotating shaft 11a of the motor 11 rotates and the magnetic field fluctuates in the power generating element 12g, the power generated by the power generating element 12g is supplied. Note that if the power generating element 12g is a Wiegand wire, it may output a positive pulse or a negative pulse. Therefore, in the encoder 12 according to this embodiment, the rectifier circuit 12a converts the pulse into a positive pulse.

[0067] The line Lg in Fig. 5(a) represents the electrical pulse output from the power generating element 12g. Note that in Fig. 5(a), a positive pulse is shown. As the power generating element 12g starts generating power from time t1, the line Lg gradually becomes larger.

[0068] The electric pulses generated and output by the power generating element 12g are stored in the first capacitor 12a2. Line Lc1 in Fig. 5(a) shows the voltage (voltage Vrc) at the second terminal T2 of the first capacitor 12a2. The first capacitor 12a2 is charged, and the voltage at the second terminal T2 gradually increases from time t2.

[0069] Furthermore, a portion of the electrical pulses generated and output by power generating element 12g is stored in second capacitor 12b1. Line Lc2 in FIG. 5(a) represents the voltage (voltage Vt) at fourth terminal T4 of second capacitor 12b1. Because second capacitor 12b1 is connected to first capacitor 12a2 via rectifier 12b2, the voltage at fourth terminal T4 of second capacitor 12b1 is lower than the voltage at second terminal T2 of first capacitor 12a2 by the amount of voltage drop across rectifier 12b2. Therefore, second capacitor 12b1 is charged, and the voltage at fourth terminal T4 gradually increases from time t3, which is a short time after time t2.

[0070] As the first capacitor 12a2 is charged with power from the power generating element 12g, the voltage at the fourth terminal T4 increases as the voltage from the power generating element 12g increases. At time tmax, when the voltage at the power generating element 12g reaches its maximum value, the voltage at the second terminal T2 also reaches its maximum value at approximately the same time. After the voltage at the second terminal T2 reaches its maximum value, the voltage gradually decreases.

[0071] Similar to the first capacitor 12a2, the second capacitor 12b1 is charged with power from the power generating element 12g, and the voltage at the fourth terminal T4 rises as the voltage from the power generating element 12g rises. At time tmax, when the voltage of the power generating element 12g reaches its maximum value, the voltage at the fourth terminal T4 also reaches its maximum value at approximately the same time. After the voltage at the fourth terminal T4 reaches its maximum value, the voltage gradually decreases.

[0072] Since the comparison element 12b5 and the like are connected to the second terminal T2 of the first capacitor 12a2, the power stored in the first capacitor 12a2 is consumed, and the voltage at the second terminal T2 gradually decreases. On the other hand, the second capacitor 12b1 is hardly discharged, and the voltage at the fourth terminal T4 hardly changes.

[0073] Therefore, at time ts, the potential of the second terminal T2 and the voltage of the fourth terminal T4 are reversed. When the potential of the fourth terminal T4 becomes higher than the potential of the second terminal T2, the comparator 12b5 outputs a positive logic voltage v1. When the comparator 12b5 outputs a positive logic voltage v1, the switch 12b6 closes the connection between the rectifier circuit 12a and the stabilized power supply circuit 12c.

[0074] At time ts, when the rectifier circuit 12a and the stabilized power supply circuit 12c are connected to each other, a predetermined voltage v2 is output from the stabilized power supply circuit 12c as shown by the line Lrg in FIG. 5(c).

[0075] The voltage at the second terminal of the first capacitor 12a2 gradually decreases, and at time t4, the stabilized power supply circuit 12c can no longer secure the voltage required to output voltage v2, and the output from the stabilized power supply circuit 12c gradually decreases.

[0076] Then, at time t5, the output of the comparison element 12b5 drops, causing the rectifier circuit 12a and the stabilized power supply circuit 12c to be disconnected from each other by opening the circuit.

[0077] <Actions and Effects> The power supply circuit and encoder disclosed herein can utilize the power supplied from the power generating element with high efficiency. According to the power supply circuit 12d of this embodiment, the first capacitor 12a2 is connected to the stabilized power supply circuit 12c after the first capacitor 12a2 is sufficiently charged by the electric pulses supplied from the power generating element 12g. That is, while the first capacitor 12a2 is being charged by the electric pulses supplied from the power generating element 12g, the first capacitor 12a2 is charged and not discharged. While the first capacitor 12a2 is being charged by the electric pulses supplied from the power generating element 12g, the first capacitor 12a2 is charged intensively, thereby enabling efficient charging of the first capacitor 12a2.

[0078] Furthermore, when the first capacitor 12a2 is sufficiently charged, power is supplied from the first capacitor 12a2 to the stabilized power supply circuit 12c, thereby stabilizing the output from the stabilized power supply circuit 12c.

[0079] Furthermore, according to the power supply circuit and encoder of the present disclosure, charging of the first capacitor 12a2 starts after the electric pulse supplied from the power generating element 12g reaches its maximum. Because charging of the first capacitor 12a2 starts after the electric pulse supplied from the power generating element 12g reaches its maximum, for example, even if the magnitude of the electric pulse supplied from the power generating element 12g fluctuates, the first capacitor 12a2 can be charged stably and efficiently.

[0080] The first capacitor 12a2 is an example of a first power storage element, the second capacitor 12b1 is an example of a second power storage element, the voltage Vrc is an example of a first potential, and the voltage Vt is an example of a second potential.

[0081] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0082] 1. Servo motor system 10 Servo motor 11 Motor 12 Encoders 12a rectifier circuit 12a1 full wave rectifier circuit 12a2 1st capacitor 12b Switching circuit 12b1 Second capacitor 12b2 rectifier 12b3 First rectifier element 12b4 Second rectifier element 12b5 Comparison element 12b6 Switch element 12c regulated power supply circuit 12c1 regulator 12d power circuit 12e Drive circuit 12f signal processing circuit 12g power generating element 12h Hall element 12m analog processing circuit 12p control circuit 20 Servo Controller

Claims

1. a power generating element that converts external energy into an electrical pulse; a first storage element having a first terminal connected to a common potential and a second terminal connected to the power generation element, storing electricity between the first terminal and the second terminal; a rectifier having a positive terminal connected to the second terminal and a negative terminal, and causing a current to flow from the positive terminal to the negative terminal; a third terminal connected to the common potential, a fourth terminal connected to the negative terminal, and a second storage element that stores electricity between the third terminal and the fourth terminal; a comparison element having a first input terminal connected to the second terminal and a second input terminal connected to the negative terminal, and outputting from an output terminal based on a potential difference between a first potential at the first input terminal and a second potential at the second input terminal; A stabilized power supply circuit; a switch element that connects or disconnects the second terminal and the stabilized power supply circuit based on an output from the output terminal; Equipped with when the first potential becomes lower than the second potential after the electric pulse is generated, the switch element connects the second terminal and the stabilized power supply circuit. power circuit.

2. The storage capacity of the first storage element is greater than the storage capacity of the second storage element.

2. The power supply circuit according to claim 1.

3. the response speed of the comparison element and the switch element is faster than the rise time of the electrical pulse; 3. The power supply circuit according to claim 1.

4. The power supplies of the comparison element and the switch element are connected to the second terminal. The power supply circuit according to any one of claims 1 to 3.

5. The power generating element is a Wiegand wire. The power supply circuit according to any one of claims 1 to 4.

6. A power supply circuit comprising: Encoder.

7. a power generating element that converts external energy into an electrical pulse; a first storage element having a first terminal connected to a common potential and a second terminal connected to the power generation element, storing electricity between the first terminal and the second terminal; a rectifier having a positive terminal connected to the second terminal and a negative terminal, and causing a current to flow from the positive terminal to the negative terminal; a third terminal connected to the common potential, a fourth terminal connected to the negative terminal, and a second storage element that stores electricity between the third terminal and the fourth terminal; A stabilized power supply circuit; A control method for a power supply circuit comprising: connecting the second terminal to the stabilized power supply circuit when a first potential at the second terminal becomes lower than a second potential at the fourth terminal after the electric pulse is generated; A method for controlling a power supply circuit.

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