JPH02256551A - Wiper controller - Google Patents

Abstract

PURPOSE:To secure the operation with high reliability for a long period by interposing a semiconductor switching element in the conduction passage of a wiper motor in the intermittent wiping mode and periodically operating a driving circuit by an interval controlling circuit. CONSTITUTION:A semiconductor switching element 8 is installed in the conduction passage of a wiper motor 5 in the case when a wiper switch 1 is switched to an intermittent mode, and in the intermittent mode, the element 8 is periodically operated by an interval controlling circuit 15. Further, the operation state of each cycle is held by a driving circuit 22 until a stable position stop switch 6 is switched to a detection state. When the drive of the driving circuit 22 is suspended, an auxiliary semiconductor switching element 9 is turned ON, and the both terminals of the wiper motor 5 are short-circuited. Further, an electric current detecting means 10 for detecting the load current which flows in the element 8 is installed, and the operation of the driving circuit 22 is suspended by a holding circuit 74 according to the magnitude of the detected load current, and the operation stop state is maintained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a wiper control device used in automobiles, etc., and particularly to a wiper control device having a function of causing the wiper to perform a wiping operation intermittently. Regarding equipment.

(Prior Art) For example, in wiper control devices for automobiles, in addition to the normal continuous wiping mode in which the wiper is driven continuously, it has become mainstream to set an intermittent wiping mode in which the wiper is driven intermittently. When setting such an intermittent wiping mode, conventionally, a relay switch is interposed in the energizing path of the wiper motor, and the relay switch is periodically turned on and off by an interval control circuit.

(Problems to be Solved by the Invention) The above conventional configuration uses a relay switch, which is a mechanical contact, as a switching element for driving the wiper motor, so there is a problem in that the reliability in terms of contact and life is relatively low. There is also the problem that the operating noise when the relay switch is turned on and off is relatively loud and harsh on the ears.

In order to deal with such problems, similar to interval control circuits that have already been converted to solid state,
It is desirable to use a solid-state switching element for driving the wiper motor, and in this case, a semiconductor switching element such as a power transistor may be used instead of a relay switch. However, semiconductor switching devices generally have the property of being easily destroyed by surge voltages or overcurrents, whereas in automobiles, surge voltages are easily generated and short-circuit currents or short-circuit currents due to dead shorts There is a unique situation in which overcurrent often flows due to the locking of the wiper motor. For this reason, it is impossible to simply convert the switching element for driving the wiper motor into a solid-state state.

In addition, the relay switch can be configured as a switching type with a make contact and a break contact, so when applying dynamic braking to the wiper motor to ensure that the wiper stops at a fixed position, the break contact of the relay switch can be used as is, but in the case of solid-state conversion as described above, a separate semiconductor switching element is required for dynamic braking of the wiper motor. However, if the semiconductor switching elements for wiper motor drive and dynamic braking are simply combined, there is a risk that they may turn on at the same time and short-circuit the power supply. In some cases, special measures are required.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the reliability of contact and life by utilizing a semiconductor switching element for intermittent driving of a wiper motor, and to improve the reliability of the contact and life of the wiper motor. It is an object of the present invention to provide a wiper control device which has effects such as being able to reliably protect the wiper and stop the wiper at a fixed position.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a wiper switch that has an intermittent mode position for causing the wiper to perform an intermittent wiping operation in addition to a continuous mode position and a stop mode position, and The wiper control device is intended for a wiper control device equipped with a fixed position stop switch that is switched to the detection state when the wiper switch is moved to the standby position. With the wiper switch set to the intermittent mode position, the main semiconductor switching element starts operating periodically by the interval control circuit, and maintains the operating state of each cycle until the fixed position stop switch is switched to the detection state. A drive circuit that turns on the main semiconductor switching element in an operating state, an auxiliary semiconductor switching element that is turned on when the drive circuit is stopped and shorts both ends of the wiper motor, and a current that detects the load current flowing through the main semiconductor switching element. a detection means, a first comparator circuit that outputs a first trip signal when the negative 41 current detected by the current detection means exceeds the first upper limit; a load current detected by the current detection means is within the first upper limit; a second comparator circuit that outputs a second trip signal after a predetermined delay time when a second upper limit lower than the value is exceeded, and when the first trip signal or the second trip signal is output; It is configured to include a holding circuit that stops the operation of the drive circuit and maintains the operation stopped state, and a surge protection circuit that stops the operation of the drive circuit when a voltage of a predetermined level or more is applied to the current carrying path of the wiper motor. be.

Furthermore, in this case, an overheat protection circuit may be provided that detects the temperature of the main semiconductor switching element using a temperature sensor and stops the operation of the drive circuit when the detected temperature exceeds a predetermined value.

(Function) When the wiper switch is switched to the intermittent wiping mode position, the main semiconductor switching element is interposed in the energizing path of the wiper motor, and the drive circuit is started to operate periodically by the interval control circuit. In the operating state, the main semiconductor switching element is turned on.

Therefore, the wiper motor is periodically energized through the main semiconductor switching element.

At this time, the drive circuit maintains its operating state only until the fixed position stop switch is switched to the detection state and until the wiper is moved to the predetermined standby position. When the wiper is moved to the standby position by energization, the wiper motor is de-energized by turning off the main semiconductor switching element in response to the stoppage of operation of the drive circuit. When the main semiconductor switching element is turned off in this way, the auxiliary semiconductor switching element is turned on and short-circuits both ends of the wiper motor.
Dynamic braking is applied to the wiper motor to accurately stop the wiper at the standby position.

As described above, the intermittent wiping operation of the wiper is performed at the cycle set in the interval control circuit.

Then, when a dead short occurs such as the power supply side terminal of the wiper motor falling to the ground when the wiper motor is energized, a short-circuit current exceeding the first upper limit value flows through the main semiconductor switching element as a load current. In this case, the first comparator circuit immediately outputs the first trip signal, and in response to this, the holding circuit holds the drive circuit in a non-operational state. As a result, the main semiconductor switching element is forcibly turned off, thereby preventing destruction of the main semiconductor switching element due to short circuit current.

Further, if the wiper motor is locked when the wiper motor is energized, a lock current greater than the second upper limit value flows through the main semiconductor switching element as a load current. In this case, the second comparator circuit outputs a second trip signal after a predetermined delay time, and in response, the holding circuit puts the drive circuit out of operation.
hold in state. As a result, the main semiconductor switching element is forcibly turned off, thereby preventing destruction of the main semiconductor switching element due to overcurrent.

Furthermore, when a voltage higher than a predetermined level is applied to the wiper motor's current-carrying path, the surge protection circuit stops the drive circuit, forcing the main semiconductor switching element to turn off. Breakdown of the main semiconductor switching element due to overvoltage can be prevented.

On the other hand, if a heating protection circuit is provided, the drive circuit will stop operating when the temperature of the main semiconductor and switching element rises above a predetermined value. The device is now forcibly turned off, thereby preventing the main semiconductor switching device from being destroyed due to abnormal temperature rise.

(Embodiment) Hereinafter, an embodiment in which the present invention is applied to an automatic heavy-duty wiper control device will be described with reference to the drawings.

In the figure, 1 is a wiper switch having terminals T1 to T7, and this can be set to a stop mode position OFF, a mist mode position MIST, or a mist mode position MIST according to the operation of an operation lever (not shown).
It is configured so that it can be switched to intermittent mode position INT, continuous mode position low mode position it\LO, and high mode position H1, respectively, and these positions are OFF, MIST,
In the state switched to INT, LO, HI, terminal T1
-T7 is selectively connected as shown in the figure. For wiper switch 1, the stop mode position is OFF, the intermittent mode position is INT, and the low mode position is LO.
When switched to the high mode position H1, the switching state is latched, but when the mist position MIST is switched to the off position OF I? The switch is configured to be switched only during a period when operating force is applied to the operating lever in the state of OFF, and to automatically return to the OFF position when the operating force is released.

2 is a washer switch with terminals W and Ew a, which is normally in the OFF position, which disconnects terminals W and Ew, but connects terminals W and Ew only during a period when an operation knob (not shown) is operated. The switch can be switched to the on position ON. 3 is a reset switch having terminals R and Rw, which is always connected to the terminal R.
Terminals R and Ew are in the OFF position where terminals R and Ew are separated, but only during the period when an operation button (not shown) is operated.
It is possible to switch to the ON position where the two are connected.

Reference numeral 4 denotes a power line through which power is supplied from an on-vehicle battery (not shown) via an ignition switch, and the terminal T1 of the wiper switch 1 is connected to this power line 4.

5 is a wiper motor for wiping a windshield wiper (not shown), which has a common terminal C1, a high-speed rotation terminal H, and a low-speed rotation terminal H, and when energized via the high-speed rotation terminal H, the wiper motor operates at a relatively high speed. As well as rotating with
Rotates at a relatively low speed when energized through the slow rotation terminal. At this time, the common terminal C of the wiper motor 5 is connected to the ground line GND, and the high speed rotation terminal H and low speed rotation terminal are connected to the terminals T2 and T3 of the wiper switch 1, respectively.

Reference numeral 6 denotes a fixed position stop switch of a well-known configuration provided on the wiper, which has a contact point (
c-b) is switched to the detection state where it is turned on, and
When the wiper is moved from the standby position, the contact (C-
a) is switched to the on state. At this time, in the fixed position stop switch 6, its contact a is connected to the power supply line 4, its contact point A is connected to the ground line GND, and its contact point C is connected to the signal line 4a.

Further, 7 is a pump motor for driving a washer pump of a well-known configuration in an automobile to inject window washer liquid onto the windshield, and this is connected between the power line 4 and the terminal W of the washer switch 2. There is.

8 is a pnp type first power transistor which is a main semiconductor switching element, 9 is an npn type second power transistor which is an auxiliary semiconductor switching element, and the collector of each of these transistors 8 and 9 is connected to the wiper switch 1.
are commonly connected to terminal T4. Further, the emitter of the first power transistor 8 is connected to the power supply line 4 via a sampling resistor 10 serving as a current detection means, and the emitter of the second power transistor 9 is connected to the ground line GND. In addition, each power transistor 8
.
3.14 is connected.

15 is an interval control circuit for determining the intermittent wiping cycle of the wiper, and this has the following FM configuration. That is, 16 is a capacitor as a timing element, one end of which is connected to the terminal T6 of the wiper switch 1, and the other end connected to the signal line 4a. 17 and 18 are IF variable resistors and resistors for configuring a time constant circuit for intermittent wiping cycles together with the capacitor 16, and one end of these series circuits is connected to the power supply line 4, and the other end is connected to the wiper switch. 1 terminal T6. Further, 19 is a resistor for charging the capacitor 16 while the wiper switch 1 is in the OFF position, one end of which is connected to the power supply line 4, and the other end of which is connected to the terminal T of the wiper switch 1.
7 is connected.

20 and 21 are resistors for discharging the charge in the capacitor 16, and one end of the series circuit of these is connected to the signal line 4a, and the other end is connected to the terminal T5 of the wiper switch 1.

In the interval control circuit 15 configured as described above, the common connection point of the resistors 20 and 21 is connected to the base of the npn transistor 23 in the drive circuit 22 via the diode 24 in the forward direction. ing. The drive circuit 22 is for turning on the first power transistor 8, and has the following configuration.

That is, the transistor 23 of the manual stage has its base
A resistor 25 is connected between the emitters, and the emitters are connected to an auxiliary ground line 26. The auxiliary ground line 26 is connected to the terminal Ew of the washer switch 2 and the terminal Rw of the reset switch 3, and a diode 27 is connected to the ground line GND.
is connected through the forward direction. 28 is output stage n
It is a pn type transistor, and its collector is connected to the base of the first power transistor 8 via a resistor 29, and its emitter is connected to the auxiliary ground line 26. Reference numeral 30 denotes a pnp type transistor at an intermediate stage, the emitter of which is connected to the power supply line 4, and the collector connected to the base of the transistor 28 via a resistor 31. Further, the base of the transistor 30 is connected via a resistor 32 to the collector of the transistor 23 of the human power stage.

33 is a brake control circuit for turning on the second power transistor 9, and this is constructed as follows. That is, the reference numeral 34 designates a pnp type transistor in the manual stage, the base of which is connected to the collector of the transistor 28 in the drive circuit 22 via a resistor 35. Further, the emitter of the transistor 34 is connected to the power supply line 4, and the collector is connected to a common connection point of a series circuit of resistors 36 and 37. One end of the series circuit of the resistors 36 and 37 is connected to the power supply line 4, and the other end is connected to the signal line 4a via the capacitor 38.

Three output stage pnp transistors have their emitters connected to the power supply line 4 and collectors connected to the base of the second power transistor 9 via a resistor 40. Further, a capacitor 4°1 is connected between the base and emitter of the transistor 39.

Reference numeral 42 denotes a washer interlocking circuit for driving the wiper in conjunction with the ON operation of the washer switch 2, which has the following configuration. That is, 43 is a pnp transistor whose emitter is connected to the power supply line 4, and whose collector is connected to the transistor 2 in the drive circuit 22 via a resistor 44, 45 and a forward diode 46.
It is connected to the base of 3. This transistor 43 has a resistor 47 connected between its base and emitter, and the base is connected to the washer switch 2 through a resistor 48.
is connected to terminal W of. 4 are capacitors for delaying the interlocking of the wiper, one end of which is connected to the power supply line 4, and the other end connected to the base of the transistor 43. 50 is a capacitor for securing the operating time when the wiper is interlocked, one end of which is connected to the common connection point of resistors 44 and 45, and the other end connected to the auxiliary ground line 2.
6.

Reference numerals 51 and 52 are a first comparison circuit and a second comparison circuit for comparing the voltage across the sampling resistor 10 with an optical reference voltage, respectively, and these will be explained below.

First, common elements of the first and second comparison circuits 51 and 52 will be explained. That is, 53 is a voltage stabilizing circuit, which connects a series circuit of a resistor 54 and a voltage regulator diode 55 with the illustrated polarity between the power supply line 4 and the auxiliary ground line 26, and connects the voltage regulator diode 55 in parallel with the voltage regulator diode 55. A constant voltage die and a cathode of an ode 55 are connected to an auxiliary power line 57. Reference numeral 58 denotes a reference voltage generation circuit, which includes resistors 59 and 60 connected in series between the power supply line 4 and the auxiliary ground line 26, and generates the reference voltage Vs from their common connection point.

In the first comparison circuit 51, 61 is a first detection voltage generation circuit, which is connected between the load side terminal of the sampling resistor 10 (corresponding to the emitter of the first power transistor) and the auxiliary ground line 26. resistors 62 and 63
are connected in series, and the first detection voltage Vdl is generated from their common connection point. A comparator 64 is supplied with power from the auxiliary power line 57, and receives the reference voltage Vs at its inverting input terminal (-) and receives the first detection voltage Vdl at its non-inverting input terminal (+). ing. At this time, the first detection voltage Vdl decreases as the load current detected by the sampling resistor 10 increases, but when the load current exceeds the first upper limit 11, Vdl< The values of the resistors 62 and 63 are set to have a relationship of Vs. Therefore, comparator 64
outputs a high level signal in a steady state because of the relationship of Vd2≧Vs, but when the detected load current of the sampling resistor 10 exceeds the first upper limit value Il, a low level signal is output as the first trip signal. Inverts to the state output as SLI. Note that the first upper limit value 11 is set to a value larger than the starting current of the wiper motor 5 and smaller than its short-circuit current.

On the other hand, in the second comparison circuit 52, 65 is a second detection voltage generation circuit, which is connected between the load side terminal of the sampling resistor 10 and the auxiliary ground line 26 by the resistors 66 and 65.
7 connected in series, and the second
Detection voltage Vd2 is generated. 68 is a comparator that is supplied with power from the auxiliary power supply line 57, and receives the reference voltage Vs at its inverting input terminal (-), and receives the second voltage at its non-inverting input terminal (10).
The detection voltage Vd2 is received. At this time, the second detection voltage Vd2 is also applied to the sampling resistor 10.
As the load current detected by A value of 66°67 is set for the resistance. Therefore, in the steady state, the comparator 68 outputs a high level signal because of the relationship of Vd2≧Vs, but when the detected load current of the sampling resistor 10 exceeds the second upper limit value I2, it outputs a low level signal. Invert to the output state.

Note that the second upper limit value I2 is set to a value slightly smaller than the lock current of the wiper motor 5, for example.

Furthermore, in the second comparison circuit 52, the output terminal of the comparator 68 is connected to the auxiliary power supply line 57 via a resistor 69.70, and the common connection point of these resistors 69.70 is connected to the base of the pnp transistor 71. It is connected. At this time, in the transistor 71, an on-delay capacitor 72 is connected between the base and emitter, the emitter is connected to the auxiliary power supply line 57, and the collector is connected to the npn transistor (described later) via a resistor 72. The transistor is connected to the transistor bus 3-. Therefore, transistor 71 is turned on only when capacitor 72 is charged to a predetermined level after comparator 68 outputs a low level signal. As a result, in the second comparator circuit 52, when the load current detected by the sampling resistor 10 exceeds the second upper limit value 2 and the output of the comparator 68 is inverted to a low level signal, the predetermined signal is When the delay time has elapsed, a second trip signal SL2 consisting of a high level signal is output from the collector of Langistav 1.

The front S self-transistor 73 forms a part of a holding circuit 74 including an R-S flip-flop, and this holding circuit 74 will be explained below.

That is, in the holding circuit 74, between the auxiliary power supply line 57 and the auxiliary ground line 26, a series circuit of a resistor 75° 76 and a capacitor 77, as well as a resistor 78 and a capacitor 79 are connected.
A common connection point between the resistor 76 and the capacitor 77 is connected to the base of the NPN transistor 80, and a common connection point between the resistor 78 and the capacitor 79 is connected to the base of the NPN transistor 81. There is.

In this case, the collector and emitter of the transistor 80 are connected to the collector and emitter of the transistor 73, respectively, and these collectors and emitters are connected to the output terminal of the comparator 64 and the auxiliary ground line 26, respectively. ing. The transistor 81 has its collector connected to the common connection point of the resistors 75 and 76 and the terminal R of the reset switch 3, and its emitter connected to the auxiliary ground line 26.

A resistor 82 and a capacitor 83 are connected in series between the collector and emitter of the transistor 81, and the base of an output stage npn transistor 84 is connected to their common connection point. The transistor 84 has its collector connected to the base of the transistor 23 in the drive circuit 22, and its emitter connected to the auxiliary ground line 26.

In addition, in the holding circuit 74 as described above, a flip-flop function is obtained by nine transistors 80 and 81, and the on state of the transistor 80 corresponds to the set state.
The on state of the transistor 81 corresponds to a reset state. In this case, the time constant τ1 of the charging circuit consisting of a resistor 75°76 and a capacitor 77, and a resistor 78. The time constant τ2 of the charging circuit consisting of seven capacitors is set in the relationship τ1>τ2. Therefore, when the power is turned on, the auxiliary power line 57
When a voltage is applied to the transistor 81, a power-on reset function is obtained in which the transistor 81 is turned on and the transistor 80 is turned off. Further, the holding circuit 74 also controls the transistor 80 when the reset switch 3 is turned on.
It is reset in response to forced off.

On the other hand, 85 is the first power! - This is a surge protection circuit for overvoltage protection of the transistor 8, and has the following configuration. That is, 86 is a constant voltage diode for overvoltage detection, and its anode is connected to the power supply line 4, and its cathode is connected between the auxiliary ground lines 26 via a protective resistor 87. It is configured to break down when an overvoltage of a predetermined level or higher is applied to the line 4. 88 is an npn transistor whose base is connected to the anode of the voltage regulator diode 86 via a resistor 89, whose collector is connected to the base of the transistor 28 in the drive circuit 22, and whose emitter is connected to the auxiliary ground line 26.
It is connected to the.

90 has a base connected to a constant voltage diode 86 via a resistor 91.
an npn type transistor connected to the anode of the transistor 39 in the brake control circuit 33;
is connected to the base of the auxiliary ground line 26 via a resistor 92, and its emitter is connected to the auxiliary ground line 26.

Reference numeral 93 denotes an overheat protection circuit for preventing thermal runaway of the first and second power transistors 8 and 9, and has the following configuration. That is, 94 represents each power transistor 8
, 9, and one end thereof is connected to the power supply line 4 via a resistor 95, and the other end is connected to the ground line GND. The base of 96 is POSISTOR 94.
An npn type transistor is connected to the common connection point of the resistor 95 and the resistor 95, and its collector is connected to the base of the transistor 23 in the drive circuit 22, and its emitter and ivy are connected to the auxiliary ground line 26. Therefore, the transistor 96 is in a normal state where the temperature detected by the POSISTOR 94 is lower than the set temperature (that is, the POSISTOR 94 is lower than the set temperature).
is off when the resistance value of POSISTOR 9 is low).
4 is turned on when the detected temperature becomes equal to or higher than the set temperature.

Note that 97 is a resistor connected between the power supply line 4 and the signal line 4a.

Next, the operation of the above configuration will be explained.

In the initial state when the power is turned on in response to turning on an ignition switch (not shown), power is supplied from the battery to the power line 4;
When the applied voltage is within the normal range, the constant voltage diode 86 in the surge protection circuit 85 does not break down, and the transistors 88 and 90 are turned off.

In addition, under normal conditions when the wiper is in a predetermined standby position,
The fixed position stop switch 6 is in a state where the contacts (c and b) are turned on. At this time, when the wiper switch 1 is switched to the stop mode position OFF, the capacitor 16 in the interval control circuit 15 is connected from the power supply line 4 to the resistor 19 and the terminal T7 of the wiper switch 1. The battery is charged through the contacts (c and b) of T6 and the localization +1 switch. Furthermore, when the power is turned on, the holding circuit 74 is switched to a reset state in which the transistor 81 is turned on and the transistor 80 is turned off due to its power-on reset function, and accordingly, the output stage transistor 84 is turned off. maintained in the state. Then, in response to the wiper switch 1 or the washer switch 2 being operated from the above state, the following operations are performed.

(1) When the wiper switch 1 is switched to the intermittent mode position INT...At this time, the terminals T3 and 14 of the wiper switch 1 and terminals T5 and 76 are connected, so the interval control In the circuit 15, the voltage level at the common connection point of the resistors 20 and 21 changes to the voltage level at the terminal T6. The voltage signal from the common node is applied to the base of the transistor 23 in the drive circuit 22 through the diode 24. Then, in the drive circuit 22, the transistors 23, 30, and 28 are sequentially turned on and switched to the operating state, and in response, the first power transistor 8 and the transistor 34 in the brake control circuit 33 are turned on. Turn it on. As a result,
From the power supply line 4 to the sampling resistor 10. First power transistor8. Terminals T4 and T3 of wiper switch 1
An energizing path is formed between the low-speed co-rotating terminal of the wiper motor 5 and the common terminal C to the ground line GND, and the wiper motor 5 is rotated at a relatively low speed. As a result, the windshield wiping operation by the wiper is started, and in response, the fixed position stop switch 6 is switched to the ON state between the contacts (ca).

In addition, in the braking control circuit 33, the transistor 39 is held in the off state as the transistor 34 is turned on as described above, so that when the first power transistor 8 is in the on state, the second power transistor 39 is held in the off state. 9
This will prevent power short-circuit accidents caused by inadvertently turning on the power supply.

As described above, the fixed position stop switch 6 is connected to the contact point (C-a
), the signal line 4a is connected to the power supply line 4, so the charge in the capacitor 16 is rapidly discharged, but the transistor 23 in the drive circuit 22 is connected to the signal line 4a. Resistance 21. It is maintained in the on state by a voltage signal applied through the diode 24.

Therefore, the first power transistor 8 and the transistor 34 remain turned on, and the wiper motor 5 continues to be energized. When the wiper returns to the standby position in response to continued energization, and the switch 6 returns to the on state between the contacts (c and b), the charge in the capacitor 16 is discharged. Therefore, transistor 23 is turned off. Then, in the drive circuit 22, the transistors 30, 28 are sequentially turned off, so the first power transistor 8 is turned off, and the wiper motor 5 is cut off.

As described above, when the first power transistor 8 is turned off in response to the transistor 28 being turned off, the brake control circuit 33 turns on the transistor 39 in response to the transistor 34 being turned off. second
The power transistor 9 of is turned on. Then, the connection between the low speed rotation terminal of the wiper motor 5 and the common terminal C is connected to the terminals T3 and T4 of the wiper switch 1. A short circuit is established via the second power transistor 9, and as a result, dynamic braking is applied to the wiper motor 5 to ensure that the wiper is stopped at the standby position. Also, at this time,
Since the surge voltage caused by turning off the first power transistor 8 is absorbed by turning on the second power transistor 9, voltage breakdown of the first power transistor 8 can be prevented.

When the fixed position stop switch 6 returns to the ON state between the contacts (c and b), the interno small control circuit 15 connects the capacitor 16 with the resistor 18 .
The flJ variable resistance resistor 17 is charged through the contacts (C-b), and when the terminal voltage of the capacitor 16 reaches a predetermined level or higher due to this charging, the drive circuit 22
The transistor 23 inside is turned on 111 times. Therefore, from this point on, the wiper wiping operation and stopping at the standby position are repeated in response to the energization and disconnection of the wiper motor 5 as described above, and thus the intermittent wiping operation of the wiper is performed. Incidentally, the cycle of the intermittent wiping operation of the wiper is the same as that of the capacitor 16. It is determined by the time constants of the variable resistor 17 and the resistor 18, and therefore, the period is determined by the time constant of the variable resistor 17 and the resistor 18.
It can be adjusted by

Then, when the wiper switch 1 is switched to the stop mode position OFF during the period when the wiper wiping operation is being performed, that is, during the period when the fixed position stop switch 6 is ON between the contacts (c and a), the above-mentioned The first power transistor 8 is maintained in the on state as described above due to the ON state between the contacts (C-a), so that the wiper motor 5 continues to be energized. Thereafter, when the fixed position stop switch 6 returns to the on state between the contacts (c and b), the second power transistor 9 is turned on in the same manner as described above. In this case, even when the wiper switch 1 is switched to the off mode position OFF, its terminals T3. Since the terminal T4 is connected, dynamic braking is applied to the wiper motor 5 in response to the second power transistor 9 being turned on, thereby ensuring that the wiper is stopped at the standby position. Note that during the period when the wiper is in the standby position, that is, the fixed position stop switch 6 is closed to the contact point (c
-b) When the wiper switch 1 is switched to the stop 1° mode position OFF while the wiper switch 1 is on, dynamic braking is applied to the above-mentioned oscillation and the wiper switch returns to the initial off state.

(II) When the wiper switch 1 is switched to the low mode position LO... At this time, the terminal TI of the wiper switch 1 is switched to the low mode position LO.

13 are connected, the power supply line 4 is connected to the terminals T1 and T3. The ground line GND is connected between the low speed rotation terminal of the wiper motor 5 and the common terminal C.
An energizing path is now formed leading to the wiper motor 5, which causes the wiper motor 5 to rotate at a relatively low speed, thereby performing a low-speed wiping operation of the wiper.

After this, if the wiper switch 1 is returned to the stop mode position OFF while the wiper is performing a wiping operation,
Since the contact (C-a) of the fixed position stop 1 and the switch 6 is turned on, the first power transistor 8 is kept in the on state as described above, and thus the wiper motor 5 continues to be energized. . When the fixed position stop switch 6 returns to the on state between the contacts (c and b), dynamic braking is applied to the wiper motor 5 in response to the second power transistor 9 being turned on, thereby ensuring that the wiper is in the standby position. will be stopped. Furthermore, when the wiper switch 1 is switched to the stop mode position OFF at a timing when the wiper is in the standby position, the wiper motor 5 is similarly dynamically braked.

(III) When the wiper switch 1 is switched to the high mode position H1... At this time, the terminal TI of the wiper switch 1 is switched to the high mode position H1.

12 are connected, the power supply line 4 is connected to the terminals T1 and T2. The ground line GN is connected between the high-speed rotation terminal H of the wiper motor 5 and the common terminal C.
A current-carrying path leading to point D is now formed, and as a result, the wiper motor 5 is rotated at a relatively high speed, and a high-speed wiping operation of the wiper is performed.

After this, when the wiper switch 1 is returned to the stop mode position OFF, the power to the wiper motor 5 is continued until the wiper moves to the standby position, as in the case (n) above, and then, Dynamic braking is applied to the wiper motor 5 to ensure that the wiper is stopped at the standby position.

(TV) Wiper switch 1 is in mist mode position Nll5
When switching to the mist mode position MIST... Such switching operation to the mist mode position MIST is performed only for a short time, and at this time, the terminal T of the wiper switch 1
I and T3 will be connected for only a short time. Therefore, the wiper motor 5 is energized and disconnected in the same way as in the case (n) above, and as a result, the wiper performs one low-speed wiping operation (if the switching operation to the mist mode position MIST is continued). The wiper is reliably stopped at the standby position when the low-speed wiping operation is completed (sometimes twice or more).

(V) When washer switch 2 is turned on...
In this case, the pump motor 7 is energized through its terminals W and Ew at the same time as the washer switch 2 is turned on, and this drives the washer pump (not shown) to drive the front Window cleaning fluid will now be sprayed onto the glass. Further, in the washer interlocking circuit 42, the transistor 43 is connected to the capacitor 4.
After a predetermined delay time has elapsed due to the charging of the capacitor 9, the capacitor 50 is charged, and the transistor 23.
8 are turned on in sequence, and the first power transistor 8 is accordingly turned on. At this time, the wiper switch 1 in the stop mode position OFF is connected to the terminal T3. Since the terminals T4 and T4 are connected, the wiper motor 5 is connected to the first power transistor 8° terminal T3. Electricity is supplied via T4, etc., and in response to this, the wiping operation of the wiper is started in conjunction with the drive of the washer pump.

Thereafter, when the on operation of the washer switch 2 is released, the pump motor 7 is cut off, the injection of the window washer liquid is stopped, and the transistor 43 is turned off. When the transistor 43 is turned off in this way, the charge in the capacitor 50 is transferred to the resistor 45. The transistor 23 in the drive circuit 22 is kept in the on state until the voltage is discharged through the diode 46 and the resistor 25 and the terminal voltage of the resistor 25 drops below a predetermined level. Therefore, the first power transistor 8 is kept in the on state for a predetermined period of time even after the on operation of the washer switch 2 is released, and as a result, even after the injection of the window washer liquid has stopped, the wiper is activated only a plurality of times. It will now perform a wiping action. In this case, of course, when the wiper stops at the standby position, braking is performed by the braking control circuit 33 in the same manner as described above.

As described above, the wiper motor 5 and the washer motor 7 can be selectively driven. Below, the function of protecting the first power transistor 8 and the second power transistor 9 from destruction will be explained. .

That is, in a state where the current conduction path of the wiper motor 5 is formed by the first power transistor 8, the power supply side terminal (low speed rotation terminal or high speed rotation terminal H) of the wiper motor 5 is
) falls to ground, and a large short-circuit current flows through the first power transistor 8 through the sampling resistor 10 and the like. The short circuit current flowing in this way is the first upper limit value set in the first comparison circuit 51! ! Therefore, in the first comparator circuit 51, when the detected load current of the sampling resistor 1° exceeds the first upper limit value 11 (the first detected voltage output from the first voltage generating circuit 61 When Vdl becomes lower than the reference voltage Vs generated by the reference voltage generating circuit 58, the first trip signal 5il (low level signal) is immediately output.

Then, in the holding circuit 74, the transistor 81
is turned off by the first trip signal Stl, and in response, the transistors 80 and 84 are turned on, thereby switching from the reset state to the set state. When the transistor 84 is turned on in this way, in the drive circuit 22, the transistor 23 . ”
30.28 are sequentially turned off and held in a non-operational state, and in response, the first power transistor 8
is forcibly turned off. In other words, when a short circuit current flows through the first power transistor 8, it is immediately turned off and the off state is maintained, thereby preventing the first power transistor 8 from being destroyed due to the short circuit current. will be done.

The set state of the holding circuit 74 as described above can be changed by turning the power back on or by turning on the reset switch 3 after removing the cause of the short circuit.
You can return to the reset state by turning on.

Furthermore, when the wiper motor 5 is locked in a state where the current conduction path of the wiper motor 5 is formed by the first power transistor 8, a large lock current is applied to the first power transistor 8 via the sampling resistor 10, etc. flows. The lock current flowing in this way is
Therefore, in the second comparison circuit 52, when the detected load current of the sampling resistor 10 exceeds the second upper limit value I2 (the second When the second detection voltage Vd2 output from the voltage generation circuit 65 becomes lower than the reference voltage Vs), and when a predetermined delay time accompanying the charging of the capacitor 72 elapses, the second trip signal 5t2 (high level signal)
Output.

Then, in the holding circuit 74, as the transistor 73 is turned on by the second trip signal St2, the transistor 81 is turned off, and in response, the transistors 80 and 84 are turned on. ,
Thus, the reset state is switched to the set state. Therefore, in this case as well, the drive circuit 22 is connected to the transistor 23,
30.28 is kept in the off state, and the first power transistor 8 is kept in the forced off state, so that the first power transistor 8
Destruction caused by overcurrent can be prevented.

In this case, since the aforementioned delay time accompanying charging of the capacitor 72 is set, the detected load current of the sampling resistor 10 temporarily exceeds the second upper limit value I2 due to the starting current of the wiper motor 5. This prevents the first power transistor 8 from being turned off unnecessarily even if the voltage exceeds the current value. Of course, the holding circuit 74
The above-mentioned set state can be reset by turning on the power again or turning on the reset switch 3.

On the other hand, when a voltage of a predetermined level or more is applied to the power supply line 4 in a state where the current conduction path of the wiper motor 5 is formed by the first power transistor 8, the voltage regulator diode 86 breaks down in the surge protection circuit 85. , transistors 88 and 90 are turned on in response. Then, in response to the transistor 88 being turned on, the drive circuit 22 is switched to a non-operational state in which the transistor 28 is turned off, so the first power transistor 8 is forcibly turned off, which causes the Destruction of the first power transistor 8 is prevented.

Further, at the same time, the transistor 39 in the brake control circuit 33 is turned on in response to the turning on of the transistor 90, so the second power transistor 9 is turned on, and thereby the first power transistor 8 is turned on. This prevents the device from being destroyed by surge voltage when it is off.

Furthermore, when the temperature of the first and second power transistors 8 and 9 rises abnormally due to thermal runaway or the like, the temperature detected by the POSISTOR 94 exceeds the set temperature in the overheat protection circuit 93, and the transistor 96 is turned on. .

Then, the drive circuit 22 becomes the transistor 23.30.28.
The first power transistor 8 is forcibly turned off, and the first and second power transistors 8 and 9 are destroyed due to abnormal temperature rise. will be prevented.

In the above embodiment, a power transistor is used as the main or auxiliary semiconductor switching element.
Instead of this, power 〇TO or the like can also be used.

[Effects of the Invention] As explained above, according to the wiper control device of claim 1, by using a semiconductor switching element for intermittent driving of the wiper motor, it is possible to improve reliability in contact and life, and Excellent effects can be achieved in that the semiconductor switching element can be protected from overcurrent and overvoltage, and the wiper can be reliably stopped in the standby position.

Further, according to the wiper control device of claim 2, an overheat protection circuit is provided which turns off the main semiconductor switching element when the temperature thereof exceeds a predetermined value. Prevents destruction due to rising! You will be able to do it.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention. In the figure, 1 is a wiper switch, 2 is a washer switch,
3 is a reset switch, 4 is a power line, 4a is a signal line, 5 is a wiper motor, 6 is a fixed position stop switch, 7
is a pump motor, 8 is a first power transistor (main semiconductor switching element), 9 is a second power transistor (auxiliary semiconductor switching element), 10 is a sampling resistor (current detection means), 15 is an interval control circuit,
22 is a drive circuit, 26 is an auxiliary ground line, 33 is a brake control circuit, 42 is a washer interlocking circuit, 51 is a first comparison circuit, 52 is a second comparison circuit, 74 is a holding circuit, 8
Reference numeral 5 indicates a surge protection circuit 193 indicating an overheat protection circuit.

Claims (1)

[Scope of Claims] 1. A wiper switch having an intermittent mode position for causing the wiper to perform an intermittent wiping operation in addition to a continuous mode position for causing the wiper to perform a continuous wiping operation and a stop mode position for stopping the wiper; a wiper control device comprising: a fixed position stop switch that is switched to a detection state when the wiper switch is moved to a standby position; and the wiper switch is set to an intermittent mode position, and the interval control circuit starts the operation periodically, and maintains the operating state of each cycle until the fixed position stop switch is switched to the detection state. A drive circuit is provided to turn on the main semiconductor switching element in an operating state, an auxiliary semiconductor switching element that is turned on to short-circuit both ends of the wiper motor when the drive circuit is stopped in operation, and a current flows to the main semiconductor switching element. A current detection means for detecting a load current, a first comparison circuit that outputs a first trip signal when the load current detected by the current detection means exceeds a first upper limit value, and a detection by the current detection means. a second comparator circuit that outputs a second trip signal after a predetermined delay time when the load current exceeds a second upper limit value that is lower than the first upper limit value; a holding circuit that stops the operation of the drive circuit when the trip signal No. 2 is output and maintains the operation stop state; A wiper control device comprising a surge protection circuit for stopping operation. 2. A claim characterized in that it has a temperature sensor that detects the temperature of the main semiconductor switching element, and is provided with an overheat protection circuit that stops the operation of the drive circuit when the temperature detected by the temperature sensor exceeds a predetermined value. The wiper control device according to item 1.