JP4199695B2 - Motor control circuit for mirror device - Google Patents

Description

  The present invention relates to a motor control circuit for a mirror device used in an electric door mirror device for a vehicle.

  The so-called door mirror for rearward confirmation provided on the side of the door panel corresponding to the driver's seat or passenger seat of the vehicle can be folded and stored by the driving force of the motor until the mirror surface is directed to the vehicle side in the vehicle width direction. There is an electric door mirror device.

  This type of electric door mirror device usually includes a folding / unfolding switch provided in the vicinity of the driver's seat of the vehicle, and the battery of the vehicle is connected to the folding / unfolding motor via this switch and the motor control circuit. The power is supplied from.

  On the other hand, in the electric door mirror device, the control circuit is configured to stop the motor when the mirror rotates to a certain unfolded position and folded position. As an example of such a control circuit, there is a configuration in which a load applied to the motor is detected, and a current flowing through the motor is interrupted when a load greater than a predetermined value is applied to the motor. It is disclosed.

Summarizing the configuration disclosed in Patent Document 1, when the mirror is rotated to the unfolded position or the folded position and further rotation is limited, and the motor is in a so-called locked state, An overcurrent (lock current) larger than the drive current flows. The above control circuit is configured to cut off the current flowing to the motor when this overcurrent flows to the motor.
JP 2002-347522 A

  By the way, an overcurrent is generated by an external force that resists the rotation of the output shaft of the motor, even if the mirror does not reach the unfolded position or the folded position as described above. For this reason, for example, with respect to the gear for decelerating the rotation of the output shaft, the viscosity of the lubricant (for example, grease) for smooth rotation of the gear increases due to deterioration or the like. As a result of the increase in rotational resistance, an overcurrent is generated even when the driving load of the motor increases as a result, or the drive current itself at the normal time increases in the same manner as the overcurrent.

  For this reason, when the above phenomenon occurs, it becomes difficult to determine whether the mirror has reached the unfolded position or the folded position due to overcurrent.

  In view of the above facts, the present invention has an object to obtain a motor control circuit for a mirror device that can reliably cut off the supply of drive current to the motor when the mirror is displaced regardless of increase or decrease of the load of the motor. is there.

  A motor control circuit for a mirror device according to a first aspect of the present invention is a motor control circuit for a mirror device for controlling a motor that displaces a mirror attached to a vehicle with a driving force, and the rotation of the motor Ripple detection means for detecting a ripple current generated in the drive current of the motor at predetermined intervals according to the number of rotations of the rotor, and whether the rotor is rotating based on the detection result of the ripple detection means Determining means for determining whether or not the rotor is not rotating based on a result of determination by the determining means, and switch means for cutting off a current supplied to the motor. Yes.

  In the motor control circuit for a mirror device according to the first aspect of the present invention, when a driving current flows through the motor, the motor is operated, and the mirror attached to the vehicle is displaced by the driving force of the motor. Further, when the motor is driven as described above, a ripple current is generated at a constant period corresponding to the rotational speed of the motor, and this ripple current is superimposed on the drive current. The ripple current periodically generated in this way is detected by the ripple detection means.

  When the mirror is displaced to a predetermined position and the displacement of the mirror is restricted, the rotation of the output shaft of the motor is indirectly restricted, and the rotation of the output shaft and thus the rotor of the motor is stopped.

  By the way, as described above, the ripple current is generated corresponding to the rotation speed of the motor. Therefore, even if the drive current is supplied to the motor, the rotation of the rotor is forcibly stopped, so that the ripple current is generated. Disappear. Therefore, in this state, the ripple current is not detected by the ripple detection means.

  Here, in the motor control circuit for a mirror device according to the present invention, if a ripple current is generated based on the detection result of the ripple detection means, the determination means determines that the rotor is rotating. If the ripple current is not generated based on the detection result of the detection means, it is determined by the determination means that the rotor is stopped, and the switch means cuts off the drive current supply to the motor based on this determination result. As a result, the motor is stopped.

  As described above, in the motor control circuit for a mirror device according to the present invention, it is determined whether or not the mirror has reached a predetermined position and is subject to displacement restriction depending on whether or not a ripple current is generated, and the drive current for the motor is determined. Decide whether to continue or shut off the supply.

  Therefore, in the motor control circuit for a mirror device according to the present invention, even if the motor load increases, the drive current is supplied as long as the rotor continues to rotate, and the mirror is surely displaced to the predetermined position. The motor can be stopped with the mirror displaced.

  A motor control circuit for a mirror device according to a second aspect of the present invention is the motor control circuit for a mirror device according to the first aspect of the present invention, wherein the ripple current is rotated by the rotor and the brush of the motor is applied to the commutator of the motor. It occurs when touching or separating.

  In the motor control circuit for a mirror device according to the second aspect of the present invention, when the drive current is supplied to the motor, the coil constituting the rotor is energized via the brush of the stator constituting the motor and the commutator of the rotor. . Thus, when the coil is energized, a magnetic field is formed around the coil. The rotor rotates by the interaction between the magnetic field formed by this coil and the magnetic field formed by a magnet (permanent magnet) provided on the yoke or the like.

  In this way, when the rotor rotates, the rotor-side commutator and the stator-side brush repeatedly contact and separate at a timing according to the rotational speed of the rotor. As described above, a ripple current is instantaneously generated when the commutator and the brush come in contact with and away from each other.

  Here, since the ripple current is generated when the commutator and the brush come in contact with each other, even if the rotational speed of the rotor changes, the ripple current is generated only by the fluctuation in the generation period. In other words, no ripple current occurs when the rotor stops.

  For this reason, it is possible to accurately determine whether or not the output shaft of the motor is stopped based on such a ripple current (that is, whether or not the mirror reaches a predetermined position and is subjected to displacement restriction).

  A motor control circuit for a mirror device according to a third aspect of the present invention is the motor control circuit for a mirror device according to the first or second aspect, wherein the signal voltage obtained by smoothing the ripple voltage value according to the ripple current is input. The determination means determines whether or not the ripple current has occurred by comparing with a reference signal having a predetermined voltage, and a pseudo voltage comparable to the signal voltage when the ripple current is generated. Triggering means for inputting to the determining means is provided, and the pseudo voltage is input to the determining means at the start of driving of the motor.

  According to the mirror device motor control circuit of the present invention, the supply of the drive current to the motor is stopped when the ripple current is not generated. However, when the motor is rotated (for example, immediately after a switch or the like is operated), since the drive current has not flowed until then, the ripple current naturally does not flow.

  However, in the motor control circuit for a mirror device according to the present invention, since the trigger unit inputs a pseudo voltage that is approximately the same as the signal voltage when the ripple current is generated at the start of motor driving, the determination unit includes the ripple current. Is determined, and a drive current is supplied to the motor. Thereby, a motor can be driven reliably.

  As described above, it is possible to reliably cut off the supply of drive current to the motor when the displacement of the mirror is restricted regardless of the increase or decrease of the load of the motor according to the present invention.

<Configuration of First Embodiment>
FIG. 1 is a block diagram schematically showing the configuration of a mirror device motor control circuit 10 (hereinafter simply referred to as “control circuit 10”) according to the first embodiment of the present invention. The circuit diagram schematically shows the configuration of the present control circuit.

  As shown in the figure, the control circuit 10 includes a switch unit 12 and a drive control unit 14. The switch unit 12 includes a pair of switches 16 and 18. The switch 16 includes three terminals 16A, 16B, and 16C. One of the terminals 16A and 16B and the terminal 16A and the terminal 16C is electrically connected, and the other is disconnected. Be able to.

  On the other hand, the switch 18 similarly includes three terminals 18A, 18B, and 18C. One of the terminals 18A and 18B and the terminal 18A and the terminal 18C is electrically connected, and the other is connected. It can be made into a disconnection state. However, the terminal 16A of the switch 16 is connected to the positive terminal of the battery mounted on the vehicle, whereas the terminal 18A of the switch 18 is grounded. The switches 16 and 18 are connected to a terminal 16B and a terminal 18B, and to a terminal 16C and a terminal 18C.

  Further, these switches 16 and 18 are set so as to be linked to each other. When the terminal 16A and the terminal 16B are connected by the switch 16, the terminal 18A and the terminal 18B are connected by the switch 18, and the switch 16 is connected. When the terminal 16A and the terminal 16C are connected, the switch 18 connects the terminal 18A and the terminal 18C.

  Further, the terminal 16 </ b> C is connected to the connection terminal 20 of the switch unit 12, and the terminal 18 </ b> C is connected to the connection terminal 22 of the switch unit 12. The connection terminal 20 is connected to the connection terminal 24 of the drive control unit 14. The connection terminal 24 is connected to one terminal of the motor 28 via the connection terminal 26. The connection terminal 22 is connected to the connection terminal 30 of the drive control unit 14. The connection terminal 30 is connected to the other terminal of the motor 28 via the connection terminal 32.

  On the other hand, as shown in FIG. 2, the drive control unit 14 includes a surge absorber 34. One end of the surge absorber 34 is connected between the connection terminal 22 and the connection terminal 24, and the other end is connected between the connection terminal 30 and the connection terminal 32.

  As shown in FIG. 1, the drive control unit 14 includes a current detection unit 36. As shown in FIG. 2, the current detection unit 36 includes a detection resistor 38. The detection resistor 38 is interposed between the connection terminal 22 and the connection terminal 24 (indirectly, one end of the motor 28), one end of which is connected to the connection terminal 24 and the other end is connected to the motor 28.

  The motor 28 is housed in a door mirror 40 (see FIG. 3) as a mirror attached to a bracket (all of which is not shown is not shown) provided on the outside of the door panel corresponding to the front seat of the vehicle. Yes. The door mirror 40 is attached to the bracket so as to be capable of reciprocating in a direction around the shaft 42 with the vehicle vertical direction as an axial direction.

  Further, the output shaft of the motor 28 is mechanically connected to the shaft 42 via a reduction gear, and when the motor 42 is driven to rotate in the forward direction, the door mirror 40 rotates in one direction around the shaft 42 when the shaft 42 rotates. When the shaft 28 is rotated by moving the motor 28 in the reverse direction, the door mirror 40 is rotated in the other direction around the shaft 42.

  When the door mirror 40 rotates to one side around the shaft 42, when the mirror surface 44 reaches a predetermined rotation position that is substantially directed toward the rear side of the vehicle, the rotation to one side around the shaft 42 is restricted by a stopper (not shown). It has a structure. On the other hand, when the door mirror 40 rotates to the other side around the shaft 42, when the mirror surface 44 reaches a predetermined rotation position that is substantially directed toward the vehicle interior side (inward in the vehicle width direction), a stopper (not shown) is provided. Thus, the rotation around the shaft 42 is restricted.

  Furthermore, as shown in FIG. 1, the drive control unit 14 includes a ripple detection unit 46 as a ripple detection unit. As shown in FIG. 2, the ripple detection unit 46 includes a capacitor 48. One end of the capacitor 48 is connected between the detection resistor 38 and the motor 28. The other end of the capacitor 48 is connected to one input terminal of the operational amplifier 50.

  The other input terminal of the operational amplifier 50 is connected to one output terminal of the bridge circuit 52 constituting the rectifying unit. The output terminal of the operational amplifier 50 is connected to one end of the diode 54.

  Further, the ripple detection unit 46 includes a resistor 56. One end of the resistor 56 is connected between one input terminal of the operational amplifier 50 and the other end of the capacitor 48. On the other hand, the other end of the resistor 56 is connected between the output terminal of the operational amplifier 50 and one end of the diode 54, and the operational amplifier 50 and the resistor 56 constitute an amplifier.

  Further, as shown in FIG. 1, the drive control unit 14 includes a ripple determination unit 58 as a determination unit. As shown in FIG. 2, the ripple determination unit 58 includes an operational amplifier 60. One input terminal of the operational amplifier 60 is connected to the other end of the diode 54.

  As shown in FIG. 1, the drive control unit 14 includes a switching unit 62 as a switch unit. As shown in FIG. 2, the switching unit 62 includes an npn transistor 64 and a pnp transistor 66. The transistors 64 and 66 are interposed between the connection terminal 30 and the connection terminal 32 (indirectly, the other end of the motor 28). Both collector terminals of the transistors 64 and 66 are connected to the connection terminal 32, and both emitters are connected. The terminal is connected to the connection terminal 30.

  The base terminal of the transistor 64 is connected to the emitter terminal of the npn transistor 68. On the other hand, the base terminal of the transistor 66 is connected to the collector terminal of the npn transistor 72 via the resistor 70. Both base terminals of the transistor 68 and the transistor 72 are connected to the output terminal of the operational amplifier 60 through the resistor 74.

  On the other hand, the collector terminal of the transistor 68 is connected via a resistor 76 to one terminal on the output side of the bridge circuit 52 as a rectifying unit. On the other hand, the emitter terminal of the transistor 72 is connected to the other terminal on the output side of the bridge circuit 52. The bridge circuit 52 is configured by connecting four diodes in a bridge shape.

  One end on the input side of the bridge circuit 52 is connected between the connection terminal 22 and the connection terminal 24, and the other end on the input side of the bridge circuit 52 is connected between the connection terminal 30 and the connection terminal 32. . One end of each power supply line of the operational amplifiers 50 and 60 is connected between one terminal on the output side of the bridge circuit 52 and the resistor 76.

  On the other hand, the other input terminal of the operational amplifier 50 is connected between the other terminal on the output side of the bridge circuit 52 and the emitter terminal of the transistor 72, and each power line of the operational amplifiers 50 and 60 is connected. The other end is connected. Thus, no matter how the switches 16 and 18 are connected, current flows from one end to the other end of both power supply lines of the operational amplifiers 50 and 60.

  Further, the ripple detection unit 46 includes a capacitor 78 and a resistor 80. One end of each of the capacitor 78 and the resistor 80 is connected between the diode 54 and one input terminal of the operational amplifier 60. On the other hand, the other ends of the capacitor 78 and the resistor 80 are connected between the other terminal on the output side of the bridge circuit 52 and the emitter terminal of the transistor 72.

  One end of a resistor 82 is connected between one terminal on the output side of the bridge circuit 52 and the resistor 76, and between the other terminal on the output side of the bridge circuit 52 and the emitter terminal of the transistor 72. Is connected to one end of a resistor 84. The other end of the resistor 82 and the other end of the resistor 84 are connected to each other, and the other input terminal of the operational amplifier 60 is connected between the other end of the resistor 82 and the other end of the resistor 84.

  If the signal (voltage) input to one input terminal of the operational amplifier 60 is larger than the signal (voltage) input to the other input terminal, a signal of a predetermined level (predetermined voltage) is output from the output terminal of the operational amplifier 60. When this signal is input to the base terminals of the transistors 68 and 72 through the resistor 74, the collector-emitter of the transistor 68 and the collector-emitter of the transistor 72 are opened.

  Further, the collector-emitter of both transistors 68 and 72 are opened, so that the collector-emitter of the transistor 64 is opened and current can flow from the emitter of the transistor 66 to the base.

  On the other hand, as shown in FIG. 1, the drive control unit 14 includes a trigger unit 86 as trigger means. As shown in FIG. 2, the trigger unit 86 includes a pair of capacitors 88 and 90. One end of the capacitor 88 is connected between the connection terminal 20 and one end of the detection resistor 38. On the other hand, one end of the capacitor 90 is connected between the connection terminal 30 and both emitter terminals of the transistors 64 and 66. Further, the other ends of the capacitors 88 and 90 are connected to one input terminal of the operational amplifier 60.

<Operation and Effect of First Embodiment>
Next, the operation and effect of the present embodiment will be described.

  As shown in FIG. 2, when the terminals 16A and 16C of the switch 16 are connected and the terminals 18A and 18C of the switch 18 are connected, first, the current rectified by the bridge circuit 52 is supplied to each of the operational amplifiers 50 and 60. The operational amplifiers 50 and 60 flow into the power supply line and become operational, and the charge stored in the capacitor 88 is released, and a voltage of a predetermined magnitude or more is input to one input terminal of the operational amplifier 60 (FIG. 4). The state of T1 in the time chart of FIG.

  In this state, the voltage input from the capacitor 88 to one input terminal of the operational amplifier 60 is higher than the voltage input to the other input terminal of the operational amplifier 60 via the bridge circuit 52 and the resistor 80. A high level determination signal Ej is output from the terminal.

  When the high-level determination signal Ej output from the operational amplifier 60 is input to the base terminals of the transistors 68 and 72 via the resistor 74, the collector-emitter of the transistor 68 is opened. The rectified current flows between the collector and emitter of the transistor 68 and further flows between the base and emitter of the transistor 64.

  Thus, when a current flows between the base and emitter of the transistor 64, the collector and emitter of the transistor 64 are opened, and the drive current I flows through the motor 28. When the drive current I having the current value Id flows through the motor 28, a current flows from the brush provided on the stator constituting the motor 28 to the rotor coil via the rotor commutator, and thereby a magnetic field is generated around the coil. Is formed.

  The rotor is rotated by the interaction between the magnetic field formed by this coil and the magnetic field formed by the magnet (permanent magnet) provided on the yoke of the motor 28, thereby being provided coaxially and integrally with the rotor. The output shaft of the motor 28 rotates (that is, the motor 28 is driven). The rotation of the output shaft of the motor 28 is decelerated by the reduction gear, and the shaft 42 is rotated around one of the axes. As a result, the folded door mirror 40 rotates in the unfolding direction.

  Further, when the motor 28 is driven and the rotor rotates as described above, the commutator repeats contact and separation with the brush at a period corresponding to the rotation speed of the rotor. A pulse-like ripple current as shown in FIG. 4 flows at the moment of contact and separation between the commutator and the brush. This ripple current is superimposed on the drive current I, and when the ripple current is generated, the current value of the drive current I becomes Ir sufficiently higher than the current value Id of the normal drive current.

  In addition to this ripple current, the drive current I includes minute noise, but the detection resistor 38 removes minute noise. Further, the voltage corresponding to the drive current I including the ripple current is input to one input terminal of the operational amplifier 50 after the direct current component of the drive current I is cut by the capacitor 48.

  Since the operational amplifier 50 and the resistor 56 constitute an amplifier as described above, a voltage amplified at a predetermined ratio with respect to the voltage input to one input terminal is output from the output terminal of the operational amplifier 50. The Further, the voltage output from the operational amplifier 50 is appropriately smoothed by the capacitor 78 and the resistor 80 and input to one input terminal of the operational amplifier 60 as the detection signal Es shown in FIG.

  In the operational amplifier 60, the detection signal Es input from one input terminal and the voltage across the resistor 82 are compared. Here, in a state where the ripple current is superimposed on the drive current I as described above, the detection signal Es exceeds the predetermined level Esh, and the ripple current is generated at the predetermined period Ts, so that the detection signal Es does not fall below a predetermined level Esh.

  For this reason, the operational signal 60 continues to output the high-level determination signal Ej from the state in which the voltage from the capacitor 48 is input. As a result, the drive current I continues to flow and the motor 28 continues to operate.

  Here, in the state where the door mirror 40 is rotated by the driving force of the motor 28, the output shaft of the motor 28 and the shaft 42 may receive resistance, and thus the rotation of the output shaft may be delayed. However, although the generation period changes (becomes longer), ripple current is generated periodically as long as the rotor of the motor 28 is rotating.

  For this reason, even if the output shaft of the motor 28 and the shaft 42 receive resistance and the rotation of the output shaft slows down, the operational signal 60 continues to be output from the operational amplifier 60. For this reason, the drive current I continues to flow, and the motor 28 continues to operate.

  Next, when the driving force of the motor 28 rotates the door mirror 40 to one side in the direction around the shaft 42 and the time T2 in FIG. 4 elapses, the mirror surface 44 reaches a predetermined rotation position that is substantially directed toward the rear side of the vehicle. Rotation of the door mirror 40 around the shaft 42 is restricted by a stopper (not shown). As described above, the rotation of the door mirror 40 is restricted, whereby the rotation of the shaft 42 is restricted, and consequently, the rotation of the output shaft of the motor 28 is restricted.

  The rotation of the rotor of the motor 28 is stopped by restricting the rotation of the output shaft of the motor 28. For this reason, the periodic contact / separation of the commutator with the brush does not occur. As described above, the ripple current is generated at the moment of contact and separation between the commutator and the brush. Therefore, the ripple current is not generated by the periodic contact and separation of the commutator with respect to the brush.

  Here, the signal level of the detection signal Es exceeds a predetermined level Esh because the ripple current that is periodically generated is superimposed on the drive current I. However, since the ripple current is not generated as described above, the signal level of the detection signal Es that has been smoothed so far including the ripple current is lowered and falls below the predetermined level Esh.

  Thus, the low-level determination signal Ej is output from the operational amplifier 60 in which the comparison between the detection signal Es that has fallen below the predetermined level Esh and the voltage across the resistor 82 is compared. Thus, the determination signal Ej changes from the High level to the Low level, whereby the collector-emitter of the transistor 68 is blocked.

  Since the collector-emitter of the transistor 68 is cut off, the base current of the transistor 64 is stopped, and the collector-emitter of the transistor 64 is cut off. As a result, the drive current I is cut off, and the supply of the drive current I to the motor 28 is stopped.

  As described above, in the present control circuit 10, the drive current I is supplied to the motor 28 or the supply of the drive current I to the motor 28 is cut off based on whether or not the ripple current is periodically generated. . For this reason, as described above, even if the output shaft of the motor 28 and the shaft 42 are subjected to resistance before the door mirror 40 reaches the predetermined rotation position and the output shaft rotates slowly, the rotation of the output shaft is delayed. The drive current I is continuously supplied to the motor 28 until the door mirror 40 reaches the moving position, and the door mirror 40 can be reliably rotated to a predetermined rotation position.

  Further, when the terminals 16B and 16C of the switch 16 are connected and the terminals 18B and 18C of the switch 18 are connected with the mirror surface 44 of the door mirror 40 facing substantially rearward of the vehicle, the direction of the driving current I Is reversed, the motor 28 is driven in reverse, and the shaft 42 rotates in the other direction around the axis.

  As a result, the door mirror 40 is rotated to the retracted position where the mirror surface 44 is directed substantially toward the interior of the vehicle. In this case as well, the above-described effects are basically obtained. The same effect can be obtained.

<Configuration of Second Embodiment>
Next, a second embodiment of the present invention will be described. In the description of the present embodiment, the same reference numerals are assigned to the same parts as those in the first embodiment, and the description thereof is omitted.

  FIG. 5 is a circuit diagram schematically showing the configuration of the mirror device motor control circuit 110 according to the present embodiment (hereinafter simply referred to as “control circuit 110”).

  As shown in this figure, the drive control unit 112 of the present control circuit 110 includes a switching unit 114 as a switching means instead of the switching unit 62 in the first embodiment. The switching unit 62 includes a normally open relay 116. The signal input terminal of the relay 116 is connected to the output terminal of the operational amplifier 60. When the high level determination signal Ej output from the operational amplifier 60 is input to the signal input terminal of the relay 116, the coil of the relay 116 is energized. Thus, the circuit is closed, whereby the drive current I flows.

  Thus, in the present embodiment, the specific structure of the switching unit 114 is different from that of the first embodiment, but the overall configuration is basically the same as that of the first embodiment. For this reason, the present embodiment basically exhibits the same operation as the first embodiment, and the same effect can be obtained.

It is a block diagram which shows the outline of a structure of the motor control circuit for mirror apparatuses which concerns on the 1st Embodiment of this invention. It is a circuit diagram which shows the outline of a structure of the motor control circuit for mirror apparatuses which concerns on the 1st Embodiment of this invention. It is a perspective view of a door mirror. It is a time chart which shows the drive current from the drive start to completion | finish of a motor, and the state of each signal. It is a circuit diagram which shows the outline of a structure of the motor control circuit for mirror apparatuses which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

10 Motor control circuit for mirror device 28 Motor 40 Door mirror (mirror)
46 Ripple detection section (ripple detection means)
58 Ripple determination unit (determination means)
62 Switching section (switch means)
86 Trigger part (trigger means)
110 Mirror device motor control circuit 114 Switching unit (switch means)

Claims (3)

A motor control circuit for a mirror device for controlling a motor for displacing a mirror attached to a vehicle with a driving force,
Ripple detecting means for detecting a ripple current generated in the driving current of the motor at predetermined intervals according to the rotational speed of the rotor of the motor;
Determination means for determining whether or not the rotor is rotating based on a detection result of the ripple detection means;
Based on the determination result of the determination means, switch means for cutting off the current supplied to the motor when the rotor is not rotating;
A motor control circuit for a mirror device, comprising: The ripple current is generated when the brush of the motor contacts or separates from the commutator of the motor due to rotation of the rotor.
The motor control circuit for a mirror device according to claim 1. A signal voltage obtained by smoothing a ripple voltage value corresponding to the ripple current is input, and the determination unit determines whether or not the ripple current has occurred by comparing with a reference signal having a predetermined voltage. Trigger means for inputting a pseudo voltage comparable to the signal voltage when a ripple current is generated to the determination means, and the pseudo voltage is input to the determination means at the start of driving the motor;
3. The motor control circuit for a mirror device according to claim 1, wherein the motor control circuit is used for a mirror device.

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