JPH1035362A - Control device of electric storage type door mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rotatably drive a drive motor for erection and storage operation reversibly without using a mechanical switch by providing two diodes connected between a source and a drain of an electric field effect transistor(FET) parasitized in the inside of the FET. SOLUTION: Specified voltage of both end voltage of a resistor R2 is applied at a rate of change set by a time constant of a differentiating circuit. Consequently, gate and spurce voltage of a second electric field effect transistor(FET) Q4 rises. Thereafter, when this voltage exceeds a specified value, the FET Q4 is put on and the drain and the source are continued from each other. Consequently, voltage from an electric source E1 is continued through a switch SW1, a partial pressure resistor R3, a first diode D1, a drive motor Ml, the second FET Q4, a partial pressure resistor R4 and a switch SW2, accordingly, the drive motor M1 is rotationally driven in the forward direction and a door mirror is revolved from an erecting position in a direction of a storage position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for controlling the standing and storing of an electric retractable door mirror, and more particularly to a technique for improving the reliability of a contact by performing a switching operation using a contactless switch. .

[0002]

2. Description of the Related Art Generally, a door mirror mounted on a vehicle and projected from the side of the vehicle for the purpose of visually observing the rear side is often obstructed when passing through a narrow road or entering a garage. There are many devices configured to be tiltable between a standing position and a storage position. The upright position is the position of the door mirror during normal driving, and is in a state of protruding to the side of the vehicle. The storage position is a state in which the door mirror is rotated rearward by approximately 90 °, and is in a folded state. Therefore, it is necessary for the driver to perform operations such as retracting the door mirror and returning to the standing position each time when entering the garage, and this operation is troublesome. Many types of door mirrors have come to be used.

[0003] As a conventional electric retractable door mirror, for example, one disclosed in Japanese Patent Application Laid-Open No. H8-40146 is known, and FIG. 7 shows a configuration of a control device of the electric retractable door mirror described in the publication. FIG. As shown in the figure, the control device comprises two switches 102, 10 that operate in conjunction with each other at both ends of a DC power supply 101.
3, and can be stored (when connected to the terminals 102a and 103a) and raised (when connected to the terminals 102b and 103b) by the changeover switches 102 and 103. When the changeover switch 102 is turned to the storage side from the off state (the state connected to 102n and 102n), the voltage of the power supply 101 is applied to both ends of the relay coil 104 via the terminals 102a and 102c and the capacitor 105. As a result, the a contact 104a is turned on, and the self-holding circuit becomes conductive. Then, a power supply voltage is applied to the drive motor 112 to drive in the storage direction.

When the door mirror is completely retracted, the drive motor 112 is forcibly prevented from rotating, so that the current value increases, and the voltage across the voltage dividing resistor 106 also increases. As a result, a current flows through the light emitting diode 109 of the photocoupler 107, and the emitter and the collector of the phototransistor 108 conduct,
Since the voltage at both ends of the relay coil 104 decreases, the excitation of the relay coil 104 is released, the a contact 104a is turned off, and the supply of the voltage to the drive motor 112 is stopped.

On the other hand, when returning the stored door mirror to the standing position, the changeover switches 102 and 103 are turned to the terminals 102b and 103b. As a result, a current flows in the opposite direction to the above case, so that the relay coil 104
Is excited, the drive motor 112 is driven to rotate in the reverse direction, and the door mirror is driven to rotate in the upright direction. And when the door mirror reaches the standing position,
Since the rotation of the drive motor 112 is forcibly stopped, the voltage across the resistor 106 increases, a current flows through the light emitting diode 111, the phototransistor 110 conducts, the excitation of the relay coil 104 is released, and the drive motor 112 stops. I will be.

In this way, by operating the changeover switches 102 and 103 which operate in conjunction with each other, the door mirror can be tilted to the upright position and the storage position electrically.
When the operation is completed, the drive motor 112 is automatically turned off.
The power supply to the power supply is stopped.

[0007]

However, in the conventional door mirror control device as described above, the operation of the drive motor 112 is turned on using a mechanical switch including the relay coil 104 and the relay contact 104a. The contact is turned off, and the mechanical contact has problems such as a short life, a large relay itself, a large circuit, and a malfunction of the contact easily occurring. If the contact 104a does not return for some reason, the power supply voltage will continue to be supplied to the drive motor 112. In such a case, the drive motor 1
There is a disadvantage that the overcurrent continues to flow through the motor 12 and burns the motor 112, and in order to prevent this, a separate protection circuit must be provided.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a reversible drive motor for standing and storing operations without using a mechanical switch. Another object of the present invention is to provide a control device for an electric retractable door mirror which can be driven to rotate at a high speed and can prevent a motor from being burned out without requiring a protection circuit.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention applies a forward voltage or a reverse voltage to a drive motor incorporated in a mirror body of a door mirror to cause the door mirror to rotate forward and reverse. In a control device for controlling the rotation of an electric retractable door mirror in which the mirror body can rotate between a standing position and a retracted position around a shaft erected on a base side, a DC power supply provided from a vehicle body side is provided. A changeover switch for switching between forward rotation and reverse rotation of the drive motor, two sets of FETs and a voltage dividing resistor interposed in series on both pole sides between the drive motor and the changeover switch, A gate of the FET, which is disposed in parallel with the drive motor,
A differentiating circuit for providing a differential characteristic voltage between the sources; a transistor for reducing or reducing a voltage value between the gate and the source of the FET when the voltage value of the voltage dividing resistor exceeds a predetermined value; And two diodes connected between the source and the drain of the FET in a parasitic manner.

The differentiating circuit comprises a first resistor, a capacitor, and a second resistor connected in series, and a voltage across each resistor is connected between a gate and a source of each FET. And

According to the present invention constructed as described above, a non-contact switch can be constituted by two FETs (field effect transistors) arranged on both sides of the drive motor, and by operating this FET, The drive motor can be driven to rotate reversibly. That is, when the changeover switch is turned to the storage side, a current flows through the differentiating circuit, a voltage is applied between the gate and the source of the FET that conducts the current in the forward direction, the FET is turned on, and the forward current flows to the drive motor. As a result, the door mirror rotates toward the storage side.
Then, when the door mirror reaches the retracted position, the rotation is forcibly stopped, thereby increasing the circuit current and increasing the voltage value applied across the voltage dividing resistor.
Since the junction transistor is turned on and the voltage between the gate and the source of the FET becomes zero or decreases, the supply of the voltage to the drive motor is stopped and the rotation is stopped.

When the stored door mirror is driven to rotate to the upright side, the contact of the changeover switch is turned to the upright side to rotate to the upright side by the same operation as described above. When it reaches the position, it will stop automatically. And according to such a configuration,
The drive motor is reversibly driven to rotate by a non-contact switch, and when it reaches a predetermined position, it stops immediately, so there are few failures and the reliability of the circuit is improved,
In addition, the circuit scale can be reduced.

Further, the on / off of the FET is controlled using the output of the differentiating circuit, and the output of the differentiating circuit becomes zero after a predetermined time elapses. Can be turned off.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of an electric retractable door mirror to which the present invention is applied. The electric retractable door mirror includes a shaft member 10 having a shaft portion 11, a mirror (not shown), and a plate outer (shaft cover). ) 30 is fitted to the frame 15 to which it is attached. A predetermined height h is provided at the bottom of the frame 15.
, A ring-shaped frame groove 17 and an arc-shaped groove 31 provided coaxially with the shaft portion 11 of the shaft member 10, and the plate stopper 14 is fixed. Also, the sliding portion S abuts and slides on the shaft member 10, the convex shaft rib 16 that loosely fits into the frame groove 17, and the loosely fits into the arc-shaped groove 31. A hole 12 having a hemispherical cross-sectional shape in which a shaft stopper 32 and a ball 13 are buried in contact with the side wall is provided.

Further, the shaft member 10 is provided with a gear 18 which is movable in the axial direction of the shaft portion 11 and whose rotation around the gear 18 is restricted, and the gear 18 is fixed to a gear 19 fixed to the frame 15. Are engaged. A ball 22 guided by a ball guide 21 abuts against the gear 18, and the ball 22 is urged downward (toward the ball 13) by a spring 26 via a washer lower 23. The other end of the spring 26 is regulated by the washer upper 25 and the plate 27.

FIG. 2 is a perspective view of the plate stopper 14 which is drawn with the surface on which the ball 13 is located as an upper surface.
Two pairs of concave and convex portions having 4a, 14b are provided symmetrically,
It constitutes an H surface (convex portion) and an L surface (concave portion).

The positioning mechanism of the electric retractable door mirror having the above configuration will be described in detail. FIG. 3 shows a shaft member 1.
FIG. 3A is a partial cross-sectional view developed along the annular plate stopper 14 to explain the contact relationship between the ball 0, the ball 13, and the plate stopper 14, and FIG. 3A shows a state in which the mirror is located at an upright position. FIG. 3 (b) shows a state where it is located at the storage position.

When the drive motor is driven, the gear 19 shown in FIG. 1 rotates, and the gear 18 meshing with the gear 19 tends to rotate. However, as described above, since the gear 18 is fixed around the axis of the shaft 11, the gear 19 fixed to the frame 15 rotates around the shaft 11 with the frame 15. When the mirror faces the upright position, the step 14a of the plate stopper 14, which is the rotation restricting means at the upright position, comes into contact with the ball 13, and the rotation of the motor stops mechanically.

When the mirror is directed toward the storage position, the shaft stopper 32, which is a rotation restricting means at the storage position, comes into contact with the groove end (step portion of the groove) of the arc-shaped groove 31, and
The rotation of the motor M stops mechanically.

FIG. 4 is an electric circuit diagram of a control device of the electric retractable door mirror to which the present invention is applied. As shown in FIG. 4, the control circuit includes a DC power supply E1 provided from a battery mounted on a vehicle and a DC power supply E1. And two notch changeover switches SW1 and SW2 that are connected to the DC power supply E1 and switch the polarity of the output voltage.
A voltage dividing resistor R is connected between the terminals c1 and c2 on the output side of W2.
3, a series connection circuit of a first FET (Nch-MOS type) Q3, a driving motor M1, a second FET (Nch-MOS type) Q4, and a voltage dividing resistor R4. In the first FET Q1 and the second FET Q2, diodes D1 and D2 are disposed in a parasitic manner, respectively, and are connected so that the source and drain directions are forward. That is, although the FETs Q1 and Q2 and the diodes D1 and D2 are separately illustrated in the figure, the diodes D1 and D2 are inevitably provided in the MOS type FET. , D2
Is being used effectively. The drains of the FETs Q1 and Q2 are connected to the input terminals of the drive motor M1.

Each terminal c1, c of the switches SW1, SW2
Between the two, a series circuit of a resistor R1, a capacitor C1, and a resistor R2 is also connected, and the series circuit forms a differentiating circuit. The emitter and the collector of the junction transistor Q1 are connected in parallel to the resistor R1 of the differentiating circuit. The base of the transistor Q1 is connected to the source of the first FET Q3 via the resistor R5. Connected to the gate.

Similarly, the emitter and the collector of the junction transistor Q2 are connected in parallel to the resistor R2 of the differentiating circuit. The base of the transistor Q2 is connected to the source of the second FET Q4 via the resistor R6. The collector is connected to the gate of Q4.

Next, the operation of the present embodiment configured as described above will be described. Normally, when the driving motor M1 is stopped, the contacts of the switches SW1 and SW2 are connected to the terminals n1 and n2. As a result, no voltage is applied to the drive motor M1, and the drive motor M1 does not rotate. When the user wants to tilt the standing door mirror to the storage position, such as when entering a garage, the changeover switches SW1 and SW2 are turned to the terminals a1 and a2, and the DC voltage supplied from the power supply E1 is changed to the terminals a1 and Terminal c1,
In addition, conduction is made to the terminal c2 through the differentiating circuit composed of R1, C1, and R2.

As a result, a predetermined voltage is applied to the voltage across the resistor R2 at a rate of change set by the time constant of the differentiating circuit.
The source voltage will increase. When this voltage exceeds a predetermined value, the FET Q4 is turned on, and conduction between the drain and the source is established. Therefore, the switch SW1, the voltage dividing resistor 3, the first diode D1, the driving motor M1, the second FET Q4, the voltage dividing resistor R4, and the switch S
The voltage from the power supply E1 becomes conductive through W2, whereby the drive motor M1 is driven to rotate in the forward direction, and the door mirror rotates from the standing position to the storage position.

Then, when the door mirror reaches the storage position,
When the ball 13 shown in FIG. 3 comes into contact with the step portion 14b, the rotation of the door mirror is forcibly stopped.
As a result, the load on the drive motor M1 shown in FIG. 4 increases, and accordingly, the value of the current flowing through the drive motor M1 starts to increase. Then, the current flowing through the voltage dividing resistor R4 also increases, and as a result, the voltage value between the resistors R4 increases. As a result, the base and emitter voltages of the transistor Q2 also increase, so that the transistor Q2 conducts between the emitter and collector.
Therefore, the voltage across the resistor R2 constituting the differentiating circuit decreases, and the voltage between the source and the gate of the second FET Q4 decreases, so that the conduction of the FET Q4 is released.
The voltage supply to the drive motor M1 stops. Therefore, when the door mirror reaches the predetermined storage position, the drive motor M1 automatically stops. In addition, even if the transistor Q2 does not operate due to some failure, the voltage across the resistor R2 gradually falls below a predetermined time constant, and when the door mirror reaches a predetermined storage position for a while, the FET Q4 is automatically turned off. Therefore, the voltage from the power supply E1 is not continuously applied to the drive motor M1.

On the other hand, when returning the door mirror in the storage position to the standing position, the changeover switches SW1 and S
Switch W2 to the opposite side so that terminals b1 and c1 and terminals b2 and c2 are in contact. Then, a voltage is applied to the differentiating circuit in a flow opposite to that described above, and a voltage having a differential characteristic is applied across the resistor R1. Therefore, this voltage is applied to the first voltage via the resistor R3.
Is applied between the source and the gate of the FET Q3, so that the FET Q3 conducts.
Second diode D2, drive motor M1, FET Q3,
A current flows through the resistor R3, and the drive motor M1 rotates in the reverse direction. This allows
The door mirror rotates from the storage position to the standing position. When the door mirror reaches the predetermined standing position, the rotation of the drive motor M1 is forcibly stopped in the same manner as described above, so that the current value increases and the voltage dividing resistor R3 The voltage value at both ends will also increase.

As a result, the voltage between the base and the emitter of the junction transistor Q1 rises,
Conducts, and lowers the voltage across the resistor R1. As a result, the FET Q3 is turned off, and the voltage supply to the drive motor M1 is stopped.

As described above, according to the present embodiment, 2
Since the two FETs Q3 and Q4 are operated as switches and the drive motor M1 is rotated forward and reverse, mechanical contacts are not used as in the prior art, and the life and reliability of the switches are both improved. . Further, since the FETs Q3 and Q4 are operated using the voltage obtained from the differentiating circuit, the voltage value given from the differentiating circuit becomes zero after a certain period of time.
Even when the voltage supply to the drive motor M1 is not stopped due to the inactivation of Q1 and Q2, the FETs Q3 and Q4 can be turned off, and it is safe without separately easing the protection circuit. Further, since the diodes D1 and D2, which are inevitably parasitic on the FETs Q3 and Q4, are used, it is not necessary to separately prepare a diode, and the cost can be reduced.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to give a predetermined time constant to the differentiating circuit of the control circuit shown in FIG.
1, R2 and the capacitance of the capacitor are calculated using the following formulas. Now, the resistor R constituting the differentiating circuit
1, the resistance value of R2 is R, the capacitance of the capacitor C1 is C, and the current value flowing through a differentiating circuit composed of a resistor R1, a capacitor C1, and a resistor R2 connected in series as shown in FIG. i. At this time, the currents i ′ and i ″ flowing on the gate side of the FET can be ignored since their values are almost zero.

Then, assuming that the voltage value supplied from the DC power supply E1 is V, a circuit equation as shown in the following (1) can be obtained. V = 2Ri + (1 / C) ∫idt (1) By solving this differential equation, the following equation (2) is obtained. i = (V / 2R) exp (−t / 2CR) (2) Assuming that the potential at point A shown in FIG.
Is given by the following equation (3). VA = iR = (V / 2) exp (-t / 2CR) (3)

For example, when the power supply voltage V is V = 12 volts, the voltage value at the point A changes as shown in the characteristic diagram of FIG. Here, the capacitance of the capacitor C1 is C = 100 μF, the resistance values of the resistors R1 and R2 are R = 56 kΩ, and each FET is driven with a gate-source voltage of 2.5 volts. Then, 2.5 is substituted for the potential VA in the equation (3), and the time t
Is obtained, t = 9.8. Therefore, the FET is turned on only for 9.8 seconds after the voltage is applied to the differentiating circuit, and this time is sufficient to store and raise the door mirror. Incidentally, in practice, the transistor Q2 is turned on momentarily by the motor starting current, and the charging current of the capacitor C1 flows, so that the FET is turned off in a shorter time than the theoretical time obtained by the above calculation. I will. Therefore, when the ON time of the FET is strictly set, it is necessary to determine the resistance values of the resistors R1 and R2 and the capacitance of the capacitor C1 by performing various experiments.

[0032]

As described above, according to the control circuit of the present invention, the door mirror is stored without using the mechanical contacts.
The drive motor for erecting can be reversibly driven to rotate, so that mechanical contacts do not deteriorate due to aging or metal fatigue as before, and can prevent malfunctions from occurring, thus ensuring reliability. Performance can be improved, and the life of the control circuit itself can be significantly extended. Further, when a predetermined storage position or a standing position is reached, the supply of voltage to the drive motor can be immediately stopped by the action of the transistor, so that the motor does not burn out. In addition, even if the transistor does not operate for some reason, the voltage value of the differentiating circuit automatically becomes zero after a predetermined time has elapsed, so that the FET is also reliably turned off after the predetermined time, so that a separate safety circuit is required. Even if it is not easy, safety can be surely secured.
Further, since the parasitic diode of the FET is effectively used, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an electric retractable door mirror to which the present invention is applied.

FIG. 2 is a perspective view of a plate stopper drawn with a surface on which a ball is located as an upper surface.

FIG. 3 is a partial cross-sectional view developed along an annular plate stopper in order to explain a contact relation between a shaft member, a ball, and a plate stopper.

FIG. 4 is an explanatory diagram showing a circuit configuration of a door mirror control device according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a differentiating circuit.

FIG. 6 is a characteristic diagram showing a potential at a point A of the differentiating circuit.

FIG. 7 is a circuit diagram showing a configuration of a control circuit of a conventional electric retractable door mirror.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shaft member 11 Shaft part 12 Hole 13 Ball 14 Plate stopper 14a, 14b Step part 15 Frame 16 Shaft rib 17 Frame groove 18, 19 Gear 21 Ball guide 22 Ball 30 Plate outer 31 Arc-shaped groove 32 Shaft stopper E1 DC power supply SW1, SW2 selector switch R1, R2 resistor C1 capacitor R3, R4 voltage dividing resistor Q1, Q2 junction transistor Q3 first FET Q4 second FET D1, D2 diode M1 drive motor

Claims (2)

[Claims] The present invention relates to a mirror motor for a door mirror, wherein a forward voltage or a reverse voltage is applied to a drive motor incorporated in a mirror body of the door mirror to cause the door mirror to rotate forward and reverse, and the mirror body is centered on a shaft erected on a base side. A control device for controlling the rotation of an electric retractable door mirror capable of rotating between a standing position and a storage position, wherein the switching device is connected to a DC power supply provided from a vehicle body side and switches between forward rotation and reverse rotation of the drive motor. A switch, two sets of FETs and voltage-dividing resistors, each of which is interposed in series on both poles between the drive motor and the changeover switch, and each of which has a drain terminal connected to the drive motor, The FET is disposed in parallel to the
A differentiating circuit for applying a differential characteristic voltage between the gate and the source of the voltage-dividing resistor when the voltage value of the voltage-dividing resistor exceeds a predetermined value.
An electric motor, comprising: a transistor for reducing or reducing a voltage value between a gate and a source of the ET; and two diodes that are parasitic inside each FET and connected between the source and the drain of the FET. Control device for retractable door mirror. 2. The differential circuit according to claim 1, wherein a first resistor, a capacitor, and a second resistor are connected in series, and a voltage across each resistor is connected between a gate and a source of each FET. The control device for an electric retractable door mirror according to claim 1.