JPH0986346A - Control circuit for wiper device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop the current flow to a wiper motor by a circuit simple in constitution when the wiper motor is locked. SOLUTION: A relay drive transistor Tr1 is turned on by a timer signal from a washer interlocking timer 1 and an intermittent operation timer 2, and a relay RY is thereby excited, so that a wiper motor M is thereby driven. When the wiper motor is brought into a lock condition while a position discrimination switch AS to be interlocked with the wiper motor is in a condition that a braking area is being judged, the excitation of the relay allows a capacitor C acting as a timer means for a relay excitation timer hold circuit 3 to start charging, and let its time be up after the period of specified time for charging has elapsed, so that the relay RY is thereby turned off. Therefore, only the provision of the relay excitation timer hold circuit 3 simple in constitution can prevent excess current from being produced when the wiper motor is locked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit of a wiper device which drives a wiper motor for a predetermined time by a drive start signal.

[0002]

2. Description of the Related Art Conventionally, in a wiper device for an automobile, in addition to continuous reciprocating motion of a wiper blade, a washer interlocking mode for moving the wiper blade for a predetermined time by a switch operation or an intermittent operation mode for moving the wiper blade at a predetermined time interval. There is. In these devices, a timer is usually used to extract a predetermined time, but the stop position of the wiper may be displaced due to malfunction of the timer.

Therefore, the applicant of the present invention, when the time is up in the braking range of the wiper device, holds the relay drive transistor in the ON state via the relay excitation holding circuit in accordance with the position discrimination signal in the braking range to perform braking. In Japanese Patent Application No. 7-167913, a wiper device was proposed in which normal braking / stopping is performed from the time of switching from the driving range to the braking range without causing braking stop due to time-up in the middle of the range. .

[0004]

In the above-mentioned automobile wiper device, when the wiper motor is locked due to an excessive load on the wiper motor during snowfall or the like, the relay excitation holding circuit operates without an intermittent switch or a washer switch. Since it operates, in order to stop the energization of the motor, it is necessary to turn off the ignition switch after turning off the intermittent switch and the washer switch.
The operation was complicated.

[0005]

SUMMARY OF THE INVENTION In order to solve such a problem and to realize a control circuit of a wiper device capable of preventing a current from flowing through the wiper motor when the wiper motor is locked with a simple circuit configuration, the present invention is provided. In the above, a wiper drive timer circuit that outputs a drive timer signal that enables the wiper motor to be driven for a predetermined time by an operation start signal, a relay that can pass a drive current to the wiper motor via an excitation-time closed contact, and the timer. A relay drive transistor that is turned on by the output of a signal to excite the relay; and a position determination switch that switches in conjunction with the wiper motor so that each position of the drive range and the braking range of the wiper motor can be determined. When determining the drive range of the determination switch, drive current is passed to the wiper motor through the non-excitation closed contact of the relay. As described above, the non-excitation closed contact is connected to the power source through the drive range determination contact of the position determination switch, and the relay is closed during excitation when determining the braking range of the position determination switch. A relay excitation timer holding circuit having timer means for turning on the relay driving transistor for a predetermined time from the start of inputting a closed contact signal upon excitation is provided in parallel with the wiper driving timer circuit for the relay driving transistor. I made it.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail based on specific examples shown in the accompanying drawings.

FIG. 1 is a diagram showing a main part of a control circuit of an automobile wiper device to which the present invention is applied. The wiper device may be capable of selecting, for example, each mode of low-speed / high-speed continuous reciprocating motion, and a circuit for performing those operations is not shown. In the present wiper device, in addition to the low speed / high speed mode, a washer interlocking timer 1 and an intermittent actuation timer 2 as a wiper driving timer circuit for performing an intermittent operation mode and a washer interlocking mode as shown in the figure. have. In the washer interlocking mode, the wiper blade is reciprocated a predetermined number of times when the washer is jetted.

As shown in FIG. 1, a control power supply line VL is connected to a positive terminal of a battery BT as a power supply via an ignition switch IG, and an operation start signal is output to the control power supply line VL. Via the washer switch SW1 for
The intermittent operation timers 2 are connected in parallel with each other via an intermittent switch SW2 for outputting an operation start signal.

The coils of the relay driving transistor Tr1 and the relay RY are connected to the control power supply line VL, and the coil of the relay RY is excited when the relay driving transistor Tr1 is turned on. Further, the control power supply line VL is connected to a normally open terminal NO which is a closed contact when the relay RY is excited. The common terminal of the relay RY is connected to the voltage side terminal of the wiper motor M.

A two-position selection type position determination switch AS is connected to the wiper motor M so as to be switched in association with the rotation of the motor. The position determining switch AS is switched to the braking terminal (black circle in the figure) side in a relatively narrow braking area including a predetermined stop position of the wiper, and is driven in a relatively wide driving area during operation of the wiper. Switch to the (white circle in the figure) side. The braking terminal of the position determination switch AS is connected to the grounded side terminal of the wiper motor M, and the drive terminal of the position determination switch AS is connected to the control power supply line VL. Position determination switch AS
Is connected to the normally closed terminal NC of the non-excited closed contact of the relay RY.

The output terminals of the washer interlocking timer 1 and the intermittent operation timer 2 (grounded when the timer is on) are connected to the base of the relay drive transistor Tr1. The base of the relay drive transistor Tr1 is The collector of the control transistor Tr2 forming the relay excitation timer holding circuit 3 is connected. The emitter of the control transistor Tr2 is connected to the normally closed terminal NC of the relay RY. In addition, the control transistor Tr
The node of the voltage side terminal of the wiper motor M and the common terminal of the relay RY is connected to the base of 2 via a resistor R1 and a capacitor C as timer means which are provided in series from the node side. The resistor R2 is a discharge resistor of the capacitor C. The emitter of the transistor Tr2 is connected to the intermittent operation timer 2, and the node between the two is grounded via the resistor R3.

The operation of the wiper device thus constructed will be described below for intermittent operation. Intermittent switch SW2
When is turned on, the intermittent operation timer 2 is started, and as shown in the time chart of FIG. 2, the time is up while the position determination switch AS is switched to the drive terminal side, and the relay RY is in the non-excitation state. However, while the position determination switch AS is switched to the drive terminal side, current can flow to the wiper motor M through the drive terminal and the normally closed terminal NC of the relay RY, so that the wiper motor M continues to rotate and the position determination switch When the AS is switched to the braking terminal side, the line is cut off and the wiper motor M is stopped by the dynamic braking.

When the switching is started from the start point, the wiper motor M can always be stopped at a predetermined position. In the intermittent mode, the intermittent operation timer 2 repeats a predetermined drive / pause time, and the above operation is repeated accordingly. Further, during charging of the capacitor C according to the present invention, the charging current thereof flows through the control transistor Tr2, so that the control transistor Tr2 is turned on during that time.

By the way, at timing T1 in FIG. 2, if the wiper motor M is locked for some reason during stoppage, the intermittent operation timer 2 is turned on at timing T2, and the relay RY is excited to cause the wiper motor M to be activated. Current may flow through the normally open terminal NO of the relay RY. Further, since the position determination switch AS remains switched to the braking terminal, the charge state of the capacitor C continues and the control transistor Tr2 continues to be turned on.

In the normal state, the control transistor Tr2 is turned off when the position determining switch AS is switched from the braking terminal side to the driving terminal side, and the wiper motor M is stopped when the position determining switch AS is switched from the driving terminal side to the braking terminal side next. But
In the locked state, even if the intermittent switch SW2 or the washer switch SW1 is turned off, the control transistor Tr2 continues to be turned on, so that the current continues to flow to the wiper motor M, but when the capacitor C is completely charged (the predetermined time t has elapsed), the control is performed. Since the transistor Tr2 is turned off,
The relay RY is in a non-excited state, and no current flows through the wiper motor M. Then, the capacitor C is discharged through the resistor R2. The resistor R3 causes the control transistor Tr2 to be turned on in the idle running region so that the wiper motor M does not stop in the idle running region when the position determination switch AS is switched from the braking terminal side to the drive terminal side.

In this way, the control transistor Tr2 is turned on for the time t determined by the capacitor C, and the control transistor Tr2 is turned on after the charging is completed.
2 can be turned off, and the control for preventing the wiper motor M from being locked and the current continuing to flow can be realized by an extremely simple circuit as shown in the figure.

The above-described operation is not limited to the intermittent operation mode. According to this circuit, as shown in FIG. Can be similarly controlled. Further, since the relay excitation timer holding circuit 3 provided with the capacitor C (timer means) has an independent circuit configuration similar to the washer switch SW1, even if a lock occurs during the washer interlocking operation, it is driven as described above. Can be turned off.

[0018]

As described above, according to the present invention, a relay exciting timer holding circuit is provided in parallel with a wiper driving timer circuit for outputting a driving timer signal to a relay capable of supplying a driving current to a wiper motor, and position determination is performed. Even when the wiper motor is locked in the braking range determination state, the relay drive transistor can be turned off after the above predetermined period of time by turning the relay drive transistor on for a predetermined period of time after the relay is excited when the switch braking range is determined. Therefore, a circuit for preventing overcurrent to the wiper motor can be realized with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of a control circuit of an automobile wiper device to which the present invention is applied.

FIG. 2 is a time chart showing an operating procedure of an automobile wiper device to which the present invention is applied.

[Explanation of symbols]

 1 Washer interlocking timer 2 Intermittent operation timer 3 Relay excitation timer holding circuit AS Position determination switch M Wiper motor RY relay SW1 Washer switch SW2 Intermittent switch Tr1 Relay drive transistor Tr2 Control transistor

Claims (1)

[Claims] 1. A wiper driving timer circuit that outputs a driving timer signal that enables a wiper motor to be driven for a predetermined time by an operation start signal, a relay that allows a driving current to flow to the wiper motor through an excitation-time closed contact, and A relay drive transistor that is turned on by the output of a timer signal to excite the relay, and a position determination switch that switches in conjunction with the wiper motor so that each position of the drive range and the braking range of the wiper motor can be determined, When the drive range of the position determination switch is determined, the drive range determination contact of the position determination switch is connected to the non-excitation closed contact so that a drive current can flow to the wiper motor through the non-excitation closed contact of the relay. While connecting to a power source, when the braking area is determined by the position determination switch, the relay is closed via an excitation-time closed contact. A relay excitation timer holding circuit having timer means for turning on the relay driving transistor for a predetermined time from the start of inputting a closed contact signal upon excitation is provided in parallel with the wiper driving timer circuit for the relay driving transistor. A control circuit for a wiper device characterized in that