JPH02290759A - Wiper controller - Google Patents

Abstract

PURPOSE:To improve the reliability for contact and service life by interposing a semiconductor switching element in an electric conduction path of a wiper motor when switching to the intermittent wiping mode position is performed, and by periodically starting the operation of a driving circuit by an interval control circuit. CONSTITUTION:A wiper switch 1 in which one of a plurality of modes is selected according to the operation of an operating lever is provided, and each collector of the first and second power transistors Tr 9 and 10 as main semiconductor switching element is connected in common with a terminal T4 which is closed in intermittent mode. Further, an interval control circuit 15 for determining the intermittent wiping cycle of a wiper is provided, and one edge of a resistor 20 for discharging the charging electric charge of a condenser 16 as time counting element is grounded through a resistor 23 in a driving circuit 22. The load electric current which flows in Tr 9 is detected through a resistor 11, and when the value becomes over a prescribed value, each trip signal is outputted from the comparison circuits 51 and 52, and the operation of the driving circuit 22 is suspended.

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 connected to the power path of the wiper motor (
1, and this relay switch is periodically turned on and off by an interval control circuit.

(Problems to be Solved by the Invention) In the conventional configuration described above, since a relay switch, which is a mechanical contact, is used as a switching cable for driving the wiper motor, there is a problem in that reliability regarding the contact and life of the relay switch 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. In this case, a conductor switching element such as a power transistor may be used instead of a relay switch.
4-conductor switching elements generally have the property of being easily destroyed by overcurrent, but in automatic transmission systems, short-circuit current due to dead circuit or 1 + overcurrent may flow due to wiper motor locking. It is in the ゛j1 emotion of special U that it often happens. For this reason, it is impossible to completely convert the switching system for driving the wiper motor into a solid state. Moreover, semiconductor switching elements suffer from temperature fluctuations due to thermal runaway. If the semiconductor switching element is forcibly turned off by a temperature switch that detects when the temperature rises, or if the semiconductor switching element is easily destroyed due to When the temperature switch returns to its original state in response to the temperature change, the semiconductor switching element may be inadvertently turned on. For this reason, when adopting the above-mentioned configuration for countering the temperature rise Lj, ancillary circuits such as (-tT) are required, which causes the problem of complicating the entire circuit configuration.

In addition, since the relay switch can be configured with a make contact and a break contact of a self-switching type, the relay switch will break when applying dynamic braking to the wiper motor to ensure that the wiper stops at a fixed position. Although the contacts can be used as they are, in the case of solid-state conversion as described above, it is necessary to separately complete the conductor switching process for the wiper motor's dynamic braking. 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-mentioned circumstances, and an object of the present invention is to improve the fS reliability with respect to contact and life by utilizing a semiconductor switching element for intermittent driving of a wiper motor, and It is possible to reliably protect the switching element from overcurrent and temperature rise, and to stop the wiper in its normal position.Furthermore, after the above-mentioned protective functions have been activated, the protective operating state is not released inadvertently. It is an object of the present invention to provide a wiper control device which exhibits such an effect that it is possible to overcome the situation in which the entire circuit {114 configurations are 1''+-I}.

[4th aspect of the invention] (Means for solving the problem) The present invention provides a wiper having an intermittent mode position for causing the wiper to perform an intermittent wiping operation in a continuous mode position and a stop 11-mo1 position. A wiper control device equipped with a switch and a fixed position stop switch that is switched to a detection state when the wiper is moved to a predetermined standby position is assumed to be a χ1 model. When the wiper switch, which is the main semiconductor switching element interposed in the current-carrying path of the wiper motor, is switched to the intermittent mode position and starts operating periodically by the interval control circuit, the operating state of each cycle is determined. a drive circuit that holds the fixed position stop switch until it is switched to a detection state and turns on the main semiconductor switching element in that operating state;
an auxiliary semiconductor switching element that is turned on when this drive circuit is stopped to short-circuit both ends of the wiper motor;
A current detection means for detecting the load current flowing through the main semiconductor switching element, a comparison circuit that outputs a trip signal when the load current detected by this current detection means has increased to a predetermined value or more, and a trip from this comparison circuit. A holding circuit that switches to a set state in which the drive circuit stops operating when a signal is output, a temperature sensor that detects the temperature at the end of main conductor switching, and when the temperature detected by this temperature sensor exceeds a predetermined value. Overheat protection 4 which forcibly switches the holding circuit to the set state and stops the drive circuit from operating +l-
A +M configuration is provided in which a circuit is provided.

(Function) When the wiper switch is switched to the intermittent wiping mode position, the main semiconductor switching element is connected to the current-carrying path of the wiper motor, and the drive circuit is started to operate periodically by the interval control circuit 1. In this operating state, the main semiconductor switching element is turned on.

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

At this time, the drive circuit maintains its operating state only until the fixed position stop switch is changed to the detection state, or until the wiper is moved to a 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 conductor 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 Urasuke 11 conductor switching element is turned on and short-circuits both ends of the wiper motor, so that dynamic braking is applied to the wiper motor and the wiper is stopped at the standby position at iTlif. It will be IL.

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

When power is applied to the wiper motor as described above, a dead short may occur such as the power supply side end r of the wiper motor falling to the ground, or the wiper motor may become locked. When an overcurrent flows, the negative current flowing through the raw semiconductor switching increases. As a result, when the negative A current detected by the current detection means increases to a predetermined value or more, the comparison circuit outputs a trip signal, and in response to this, the holding circuit stops the operation of the drive circuit. The state changes to set 1. As a result, the main semiconductor switching element is forcibly turned off, thereby preventing destruction of the main semiconductor switching element due to overcurrent.

In addition, when the temperature of the main semiconductor switching element rises above a predetermined value when the wiper motor is energized to χ,1, the overheat protection circuit forcibly switches the holding circuit to the set state based on the output of the temperature sensor and drives the wiper motor. Deactivate the circuit. As a result, the main conductor switching element is forcibly maintained in the OFF state, thereby preventing the main semiconductor switching element from being destroyed due to temperature rise, and subsequently Even if the temperature of the switching element drops, there is no possibility that I[j will be turned on.

(Example) Hereinafter, an example in which the present invention is applied to an automobile Ill wiper control device will be described with reference to the drawings.

In the figure, 1 is a wiper switch whose terminals T1 to T7 are white. This is a wiper switch that switches between stop IL mode position OFF, mist mode position MI
ST, intermittent mode position INT, continuous mode position low mode position LO and high mode position Hl, and each of these positions OFF, MIST, I
In the state switched to NT, LO Hl, the terminal rT1
- T7 are 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 L.
When switched to O and high mode position Hl, the 1st switching state is latched, but if there is a mistake 1/position MIS
T can be changed only during the period when operating force is applied to the operating lever while it is in the OFF position OFF; IJ can be changed to T, and when the operating force is released, the OFF position is OFF.
$1,i is configured to automatically return to.

Reference numeral 2 denotes a washer switch with ends 7-W and Ew set to H. This is always in the off position OFF, which separates end W and Ew, but end W is only in the period when an operation switch (not shown) is operated. ON position ON connecting between and Ew
It is now possible to switch to Note that the end -rEw of this washer switch 1 is connected to the ground line GND.

Reference numeral 3 indicates a power supply terminal connected to the ignition switch via the ignition switch for the uncombined battery, 4 indicates a power supply line connected to this power supply terminal, and terminal T1 of the wiper switch 1 is connected to this power supply line 4. It is connected to the.

5 is a wiper motor for wiping a windshield wiper (not shown), which connects a common terminal C, a high-speed rotation terminal H, and a low-speed rotation terminal L to 6, and when energized through the high-speed rotation terminal H, the wiper motor is relatively As it rotates at high speed,
When energized via the low speed rotation terminal L, it rotates at a relatively low speed. At this time, if the common end rC of the wiper motor 5 is connected to the ground line GND, the high speed rotation terminal H and the low speed rotation end j"-L or the terminals T2 and T of the wiper switch l are connected to the ground line GND. The sea urchins are connected to each other.

Reference numeral 6 denotes a fixed position stop switch of a well-known configuration provided on the wiper, which contacts (c) when the wiper is in a predetermined standby position.
-b) is switched to the detection state in which it is turned on, and when the wiper is moved from the standby position, the contact (C-a
) can be 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.
The contact b is connected to the ground line GND, and the contact C is connected to the signal line 7. Further, 8 is a bomb motor for driving a washer bomb of a well-known configuration to inject windshield washer fluid onto the windshield in an automatic vehicle, and this is connected between the power line 4 and the terminal W of the washer switch 2. There is.

9 is the first power of the PNP type which is the main semiconductor switching element! - The transistor 10 is an n p n type second power transistor which is a semiconductor switching line T, and the collectors of each of these transistors 9 and 10 are commonly connected to the terminal T4 of the wiper switch 1. Also, the first
The emitter of the second power transistor 9 is connected to the power supply line 4 via a sampling resistor 11 serving as a current detection stage, and the emitter of the second power transistor 10 is connected to the ground line GND. A flywheel diode 12 with the illustrated polarity is connected between the collector and emitter of the second power transistor 10, and a resistor 1'3.14 is connected between the base and emitter of each power transistor 9.10. There is.

Reference numeral 15 denotes an interval control circuit for determining the intermittent wiping cycle of the wiper, and this circuit has the following configuration.

That is, 16 is a capacitor as an 11 o'clock 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 7. 17 and ]8 are variable resistors and resistors for constructing a time constant circuit for intermittent wiping cycles together with the capacitor]6, 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, ]9 is a resistor for charging the capacitor 16 while the wiper switch 1 is in the OFF position.One end of the resistor is connected to the power supply line 4, and the resistor is connected to the terminal T7 of the wiper switch 1.
It is connected to the.

20 is a resistor for supplying the charging voltage 6:f of the capacitor 16 to bk, one end of which is connected to the terminal T5 of the wiper switch 1.
The other end is connected to the auxiliary ground line 24 via a forward diode 21 and a resistor 23 in the drive circuit 22 . In addition, this auxiliary ground line 24 is
It is connected to the ground line GND via a diode 25 in the forward direction. Further, a series circuit of a resistor 20a and a diode 21a having the illustrated polarity is connected between the signal line 7 and the cathode of the diode 21.

The drive circuit 22 is for turning on the first power transistor 9, and has the following configuration.

That is, the human power stage includes an n-type transistor 26, which has the resistor 23 connected between its base and emitter, and whose emitter is connected to the auxiliary ground line 24. . Reference numeral 27 denotes an npn type transistor at the output stage, the collector of which is connected to the base of the first power transistor 9 via a resistor 28, and the emitter connected to the auxiliary ground line 24. Reference numeral 29 denotes a pnp type 1 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 1 transistor 27 via a resistor 30. Further, the base of the transistor 20 is connected to the collector of the transistor 26 of the human power stage via a resistor 1.

32 is a braking control circuit for turning on the second power transistor 10, which is configured as follows. That is, 33 is a pnp type transistor at the input stage, the base of which is connected to the collector of the transistor 27 in the drive circuit 22 via a resistor 34. Further, the emitter of transistor 1.3'3 is connected to the power supply line 4, and the collector is connected to the common connection point of the series circuit of resistors 35 and 36. The above resistance 3'5. One end of the 36 series circuits is connected to the power supply line 4, and the other end is connected to the signal line 7 via a capacitor 37.

Further, a resistor 38 is connected between the ry source line 4 and the signal line 7. Reference numeral 39 denotes an output stage i][II) type transistor whose emitter is connected to the power supply line 4 and whose collector is connected to the base of the second power transistor 10 via a resistor 40. Moreover, in such a transistor 39, its base is located at the front. ] - It is connected to the collector of the transistor 33, and a capacitor 41 is also connected between the base and emitter.

Reference numeral 42 denotes a washer interlocking path II for driving the wiper in conjunction with the ON/V operation of the washer switch 2, which has the following configuration. That is, 43 is pnp
A type 1 transistor whose emitter is connected to the power supply line 4 and whose collector is connected to the base of the transistor 26 in the drive circuit 22 via a resistor 44, 45 and a forward diode 46 in series. . This transistor 43 has a resistor 47 connected between its base and emitter, and its base is connected to the end 1w of the washer switch 2 via a resistor 48. 49 is a capacitor 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 to ensure the operating time when the wiper is linked, one end of which is connected to the resistor 44.4
The other end is connected to the auxiliary ground line 24.

Reference numerals 51 and 52 are a first comparison circuit and a second comparison circuit for comparing the voltage across the sampling resistor 11 with different reference voltages, 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, and when a series circuit of a resistor 54 and a negative voltage regulator diode 55 (not shown) is connected between the power supply line 4 and the auxiliary ground line 24, the voltage regulator diode 55 is connected to J1. A capacitor 56 is connected in parallel with the voltage regulator diode 55, and the cathode of the constant voltage diode 55 is connected to an auxiliary power supply line 57. Further, 58 is a basic voltage generation circuit, in which resistors 5Qa and 59b are connected in series between the power supply line 4 and the auxiliary ground line 24, and a constant voltage diode 60 with the polarity shown is connected in parallel with the resistor 5Qb. A random voltage Vs is generated from the cathode of the constant voltage diode 60.

In the first comparator circuit 51, 61 is the first detection voltage generation circuit, which is the negative t of the sampling resistor 11: '4 side end J' (Thil power 1, transistor 9
Resistors 62 and 63 are connected in series between the ground line 24 (corresponding to the emitter of the ground line) and the auxiliary ground line 24, and a first detection voltage Vdl is generated from their common connection point. 64 is a comparator supplied with power from the auxiliary power supply line 57, and when it receives the basic voltage Vs at its inverting input terminal (1), it becomes Jl:
The non-inverting input terminal (+) receives the first detection voltage Vdl. At this time, the first detection voltage Vdl decreases as the load current detected by the sampling resistor 11 increases, but when the load current exceeds the first upper limit of 1st shift 1l, Vdl decreases. (11<Vs
The values of the resistors 62 and 63 are set so that the relationship is as follows. Therefore, in the steady state, the comparator 64 indicates that Vold≧Vs
Although a high-level signal is output because of the relationship, the negative 61 current of the sampling resistor 11 exceeds the first upper limit value l.
When it exceeds 1, it is inverted to a state in which a low level signal is output as the first trip signal Stl. In addition, the above 1st
The upper limit value 1t is set to a value larger than the starting current of the wiper motor 5 and smaller than the short-circuit current of the wiper motor 5.

In addition, a capacitor 64a is connected between both terminals of the comparator 64.
is connected.

- Jj, in the second comparison circuit 52, 65 is the second
This is a detection voltage generation circuit that has a low resistor 6 connected between the load side terminal of the sampling resistor 11 and the hD auxiliary ground line 24.
6 and 67 are connected in series, and a second detection voltage Vd2 is generated from their common connection point. A comparator 68 is supplied with power from the auxiliary power supply line 57, and receives the reference voltage Vs at its inverting input terminal (1) and receives the second detection voltage Vd2 at its non-inverting input terminal (+). . At this time, the second detection voltage V (12) also decreases as the load current detected by the sampling resistor 11 increases, but the negative current I is lower than the first upper limit value I1. The value of the resistor 66.67 is set so that the relationship Vd2<Vs holds when the second upper limit is exceeded.Therefore, the comparator 68 holds the relationship Vd2≧Vs in the steady state. Therefore, a high level signal is output, but the detected load current of the sampling resistor 11 is
When the upper limit value I2 is exceeded, the state is reversed to output a low level signal. Note that the second upper limit value 12 is set, for example, to a value slightly smaller than the lock current of the wiper motor 5.

Furthermore, in the second comparator circuit 52, the output terminal of the comparator 68 is connected to the auxiliary power supply line 57 via a resistor 69.70.
The common connection point of these resistors 69 and 70 is pn
It is connected to the base of p-type transistor 71. At this time, in the transistor 71, if the 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 through the resistor 73a. npn (described later)
It is connected to the base of the type transistor 7゛3.

Therefore, the 1 transistor 71 is turned on only when the capacitor 72 is charged to a predetermined level after the low level 1ri is output from the comparator 68. As a result, in the second comparator circuit 52, when the load current detected by the sampling resistor 11 exceeds the second upper limit value I2 and the output of the comparator 68 is inverted to a low level signal, a predetermined delay is performed thereafter. When the time has elapsed, the collector of the transistor 71 outputs a second trip signal SL2 of high level 13.

The front 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, Ho T. In the '7 circuit 74, resistors 75 and 7 are connected between the auxiliary power supply line 57 and the auxiliary ground line 24.
6. A series circuit of capacitor 77 is connected to a series circuit of resistor 78 and seven capacitors, and resistor 7
A common connection point between the resistor 78 and the capacitor 77 is connected to the base of the np n-type transistor 80, and a common connection point between the resistor 78 and the capacitor 79 is connected to the base of the np n-type transistor 81.
connected to the base of. In this case, the collector and emitter of the transistor 80 are connected to the collector and emitter of the transistor 73,
These collectors and emitters are
is connected to the output end r of the auxiliary ground line 24. !・The collector of the transistor 81 is the resistor 7
5.76, and its emitter is connected to the auxiliary ground line 24.

Furthermore, a resistor 82 and a capacitor 83 are connected in series between the collector and emitter of the transistor 1. The base of an npn transistor 84 for the output stage is connected to the connection point. and,
The transistor 84 has its collector connected to the base of the transistor 260 in the drive circuit 22, and its emitter connected to the auxiliary ground line 24.

In addition, in the holding circuit 74 as described above, a flip-flop function is obtained by the transistors 80 and 81.
The on state of transistor 80 corresponds to a set state, and the on state of transistor 81 corresponds to a reset state.

In this case, the time constant τ1 of the charging circuit consisting of resistor 7576 and capacitor 77 and the time constant τ2 of the charging circuit consisting of resistor 78 and capacitor 79 are set to have a relationship of 2 with τ1>, and therefore, when the power is turned on, Sometimes 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 8o is turned off.

On the other hand, 85 is a surge protection circuit for maintaining overvoltage of the first power transistor 9, and has the following {IIt configuration. That is, 86 is a constant voltage diode for overvoltage detection, whose cathode is connected to the power supply line 4.
At the same time, the anode is connected between the auxiliary ground lines 24 via a protective resistor 87, so that {h has been completed. 88
is an npn type transistor whose base is connected to the anode of a voltage regulator diode 86 through eight resistors, whose collector is connected to the base of the transistor 27 in the drive circuit 22, and whose emitter is connected to the anode of the voltage regulator diode 86. One concubine is attached to Ichisuke Grand Line 24.

Reference numeral 90 denotes an overheat protection circuit for preventing thermal damage and L of the first power transistor 9, and has the following configuration. That is, 91 is a POSISTOR (positive temperature coefficient thermistor) which is a temperature sensor provided to detect the temperature of the power transistor 9, one end of which is connected to the auxiliary power supply line 57 via a low resistor 92, and the other end is is connected to the auxiliary ground line 24. 0 is an n p whose base is connected to the common connection point of the POSISTOR 91 and the low resistor 92.
It is a type II 1 transistor, and its collector is connected to the base of the 1 transistor 81 in the holding circuit 74, and its emitter is connected to the Urasuke ground line 24. Therefore, the transistor 93 is
In the normal state where the temperature detected by the POSISTOR 91 is lower than the set temperature (that is, the resistance value of the POSISTOR 91 is low), it is turned off, but it is turned ON when the temperature detected by the POSISTOR 91 becomes equal to or higher than the set temperature.

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 the 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 transistor 88 is turned off. Further, in a normal state where 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. In this state, when the wiper switch 1 is switched to the stop mode position OFF, the capacitor 16 in the interval control circuit
from the resistor 19 and the terminals T7, . . . of the wiper switch 1. T
6 and the contacts (c-b) of the fixed position stop switch 6. 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 transistors 80 are turned off one by one due to its power-on reset function, and accordingly, the output stage is turned off. The transistor 84 is kept in an off 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...6 At this time, the end J'-T' of the wiper switch 1
3, T4 and T'5, T6 are connected, the terminal voltage of the capacitor 16 in the charged state as described above in the interval control circuit 15 causes the voltage in the drive circuit 22 to become connected. The base potential of the transistor 26 is connected to the terminals T6, T5, the resistor 20, the diode 21 . The voltage immediately begins to rise through the resistor 23, and the transistor 26 is accordingly turned on. Then, drive circuit 2
2, the transistors 20 and 27 are also turned on sequentially to enable the IuJ to operate, and in response, the first power transistor 9 and the brake control circuit 32 are turned on.
Turn on 1 transistor 33.

When the first power transistor 9 is turned on as described above, the power supply line 4 is connected to the sampling resistor 11, the first receiver 1/transistor 9, the terminals T4 and T' of the wiper switch 1, and σ( of the wiper motor 5). An energizing path is formed between the fast rotation terminal L and the common terminal C to the ground line GND, and the wiper motor 5 is rotated at a relatively low speed.This causes the wiper to start wiping the windshield. In response to this, the fixed position stop switch 6 is switched to a state where the contacts (ca) are turned on.

In addition, in the brake control circuit 32, the transistor 39 is held in the off state as the transistor '3'3 is turned on as described above, so that the first power 1.
This prevents the power supply short circuit 1jt from occurring due to the second power transistor 10 being inadvertently turned on when the transistor 9 is turned on.

As described above, the fixed position stop 11 switch 6 is connected to the contact point (C-
a) When the signal line 7 is turned on, the signal line 7 connects to the contact point (
Since the capacitor 16 is connected to the source line 4 via the signal line 7, the charged voltage 6:f of the capacitor 16 is discharged, but the transistor 26 in the drive circuit 22 is connected to the signal line 7 It is maintained in the on state by a voltage signal applied through the diode 20a and the diode 21a. Therefore,
The first power transistor 9 and the transistor 33 remain turned on, and the wiper motor 5 continues to be energized. In response to continued energization, the wiper returns to the standby position, and the fixed position stop switch 6 closes the contact point (c-b
) Returns to the on state, at this time the charge in the capacitor ]6 has been discharged, so the transistor 1 is turned off. Then, in the drive circuit 22, the transistors 2Q and 27 are sequentially turned off, so the first power transistor 9 is turned off, and the wiper motor 5 is cut off.

When the first power transistor 9 is turned off in response to the transistor 27 being turned off as described above, the brake control circuit 32
In this case, the transistor 39 is turned on when the transistor 33 is turned off, and the second power transistor 10 is turned on in response. Then, the low speed rotation terminal L and the common terminal C of the wiper motor 5 are short-circuited via the terminals T'3 and T4 of the wiper switch 1 and the second power transistor 10, and this causes the wiper motor 5 to perform dynamic braking. is applied to ensure that the wiper is stopped at the standby position. Further, at this time, the surge voltage caused by turning off the first power transistor 9 is absorbed by turning on the second power transistor 0, so that voltage breakdown of the first power transistor 9 is prevented. It becomes like this.

When the fixed position stop switch 6 returns to the ON state between the contacts (c and b), the interval control circuit 15 connects the resistor 18, I'l from the power supply line 4 to the capacitor 16.
Charging begins to occur between the J variable resistor 17 and the contact point (c-b), and as a result of this charging, the terminal 7u of the capacitor 16
When the pressure reaches a predetermined level or higher, the 1 transistor 26 in the drive circuit 22 is turned on +1j. Therefore, from this point on, the wiping operation of the wiper and the operation of stopping at the standby position in response to the energization and de-energization of the wiper motor 5 as described above are repeated, and thus the intermittent wiping operation of the wiper is performed. The period of the intermittent wiping operation of the wiper is determined by the time constants of the capacitor 6, the variable resistor 17, and the resistor 18, and therefore, the period can be adjusted by the variable resistor 17.

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 turning on between the contacts (ca), the above contact ( The first power transistor 9 is kept in the on state at the same peak as described above by turning on between C and a), and thus the wiper motor 5 continues to be energized.

Thereafter, when the fixed position stop 11 and the switch 6 return to the on state between the contacts (c and b), the second power transistor 10 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 and T4 are connected, so that dynamic braking is applied to the wiper motor 5 in response to the second power transistor 10 being turned on. This ensures 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 not in contact (
When the wiper switch 1 is switched to the stop mode position OFF while the period C-b) is on, dynamic braking is applied in the same manner as described above, and the state returns to the initial state.

(n) When the wiper switch 1 is switched to the low mode position LO... At this time, the terminals TI and T3 of the wiper switch 1 are connected, so the power supply line 4 is connected to the terminal T1. and T3, a current-carrying path is formed between the low-speed rotation terminal L and the common terminal C of the wiper motor 5 to the ground line GND, whereby the wiper motor 5 is rotated at a relatively low speed and the wiper performs a low-speed wiping operation. will be held.

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 contacts (c and 1a) of the fixed position stop switch 6 are turned on, the first power transistor 9 is kept in the on state 17 as described above, and the wiper motor 5 is thereby continued to be energized. Then, 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 ON of the second power 1 transistor 10, and the wiper is moved to the standby position. will definitely 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 Hl... At this time, the terminals Tl and T2 of the wiper switch 1 are connected, so the power supply line 4 is connected to the above terminal. J
'A current-carrying path is formed between TI and T2, the high-speed rotation terminal H of the wiper motor 5, and the common terminal C to the ground line GND. A wiping operation is performed.

After this, when the wiper switch 1 is returned to the stop mode position OFF, the wiper motor 5 is energized only until the wiper moves to the standby position, as in the case (n) above, and then the wiper motor 5 is applied with dynamic braking to ensure that the wiper stops at the standby position 1#-. be done.

(IV) Wiper switch 1 is in mist mode position MIST
When switching to the mist mode position MIST, such a switching operation to the mist mode position MIST is performed only for a short time.
, 73 will be connected for a short period of time. Therefore, the wiper motor 5 is energized and disconnected in the same way as in the case (II) above, and as a result, the wiper performs one low-speed wiping operation (the switching operation to the mist mode position M I ST continues). In some cases, the wiper is reliably stopped at the standby position when the low-speed wiping operation is completed.

(V) When washer switch 2 is turned on・
In this case, the pump motor 8 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 bomb (not shown) to close the windshield. Window washer fluid will now be sprayed. In addition, in the washer interlocking circuit 42, the transistor 43 turns on after a predetermined delay time has elapsed due to the charging of the four capacitors, and the capacitor 50 is charged accordingly. Ransistor 26.29.2
7 are turned on in sequence, and along with this, the first power 1 and run star 0 are turned on. At this time, the stop mode position is OFF.
Since the wiper switch 1 located at The wiping operation is started in conjunction with the drive of the washer bomb.

Thereafter, when the on operation of the washer switch 2 is released, the bomb motor 8 is cut off, the windshield washer ifU stops blowing n.1, and the transistor 43 is turned off. When the transistor 43 is turned off in this way, the charging load of the capacitor 50 is discharged through the resistor 45, the diode 46, and the resistor 23, and the voltage at the terminal of the resistor 23 drops below a predetermined level. In this case, the transistor 26 in the drive circuit 22 is kept on. Therefore, the first power 1/transistor 0 is also kept in the on state for a predetermined period l11j after the on operation of the washer switch 2 is released. will perform a wiping action multiple times. In this case, of course, when the wiper stops at the standby position, braking is performed by the braking control circuit 32 in the same manner as described above.

As described above, the wiper motor 5 and the pump motor 8
The function of protecting the first power transistor 9 from destruction will be described below.

That is, in a state where the winding path of the wiper motor 5 is formed by the first power transistor 9, a dead end occurs such as the power supply side terminal (low speed rotation terminal L or high speed rotation terminal H) of the wiper motor 5 falling to the ground. In the event that a signal 1 occurs, a large short-circuit current flows through the first power transistor 9 via the sampling resistor 11 and the like. The short-circuit current flowing in this way is larger than the first upper limit value I1 set in the first comparator circuit 5], and therefore, in the first comparator circuit 51, the detected load current of the sampling resistor l1 is 1 (when the first detection voltage Vold output by the first voltage generation circuit 61 becomes lower than the reference voltage Vs by the reference voltage generation circuit 58), the first Lip signal Stl (low level signal)
Output.

Then, in the protection circuit 74, the charge of the seven capacitors becomes 7 due to the first 1 lip {d SLI.
When A7Li is turned off and the 1 transistor 81 is turned off, the 1 transistors 80 and 84 are turned on in response, thereby switching from the reset state to the set state. In this way, When the transistor 84 is turned on, the drive circuit 22 turns on the transistor 26.
, 2Q, and 27 are sequentially turned off and held in an inoperative state, and in response, the first power transistor 9 is forcibly turned off. In other words, when a short circuit current flows through the first power transistor 9, it is immediately turned off and the off state is maintained.
Thus, damage caused by short circuit current of the first power transistor 9 can be prevented.

Incidentally, the set state of the holding circuit 74 as described above can be returned to the reset state by performing the ++r input operation of the electrical outlet after removing the cause of the short circuit.

In addition, when the wiper motor 5 is locked in a state where the winding path of the wiper motor 5 is formed by the first power transistor 9, the first power transistor 9 is connected to the first power transistor 9 via the sampling resistor 11, etc. Large lock current flows. The lock current flowing in this way is
It is larger than the second upper limit value +2 set in the second comparison circuit 52, and therefore, in the second comparison circuit 52, the detected negative 6:f current of the sampling resistor 11 exceeds the second upper limit value I2. (When the second detection voltage d2 output by the second voltage generation circuit 65 becomes lower than the J!Kuwa voltage Vs), the capacitor 72 is charged? When the predetermined delay time between IJ and IJ has elapsed, the second trithop signal S[
2 (high level signal) is output.

Then, in the holding circuit 74, the transistor 73 is turned on by the second 1 lip (SL2), and the transistor 8 is turned off. - The transistors 80 and 84 are turned on, thereby switching from the reset state to the set 1 state. Therefore, in this case as well, the drive circuit 22 performs the operation in which the transistors '>6.2q, 27 are turned off. In addition to being held in a stopped state, the first power transistor 9 is also kept in a forced off state, thereby preventing the first power transistor 9 from being destroyed due to overcurrent. .

In this case, since the aforementioned delay time accompanying charging of the capacitor 72 is set, the detected load current of the sampling resistor 11 temporarily exceeds the second upper limit value I2 due to the starting current of the wiper motor 5. This prevents the first power 1/transistor 0 from being turned off unnecessarily even if the voltage exceeds the voltage. Of course, the holding circuit 7
The above-mentioned state of No. 4 can be reset by turning the power back on.

On the other hand, in a state where the current conduction path of the wiper motor 5 is formed by the first power transistor 9, the fls 117
When a voltage higher than a predetermined level is applied to the line 4, a constant 7u voltage diode 8 is connected in the surge protection circuit 85.
6 breaks down, and in response transistor 88
is turned on. Then, the drive circuit 22
7 is turned off and the operation is stopped, so the first power!・The transistor 9 is now forcibly turned off, which causes the first power 1 due to the overvoltage to
The destruction of transistor 0 is prevented.

Furthermore, when the temperature of the first power transistor 9 abnormally increases due to thermal V running, etc., the overheat protection circuit 9
At this point, the temperature of 41 degrees detected by the POSISTOR 91 becomes equal to or higher than the set temperature, and the transistor 93 is turned on. Then, in the holding circuit 74, the capacitor 79 is charged? ! i
6:7 is discharged through transistor 93, turning off transistor 81, and in response, transistor 8L1.84 is turned on, thereby forcibly switching from the reset state to the set state. Therefore, in this case as well, either the drive circuit 22 or the transistors 26, 2
9.27 is turned off, and the first power transistor 9 is kept in a forced off state, thereby preventing thermal runaway of the first power transistor 1 and transistor 9. - When the resulting destruction is prevented, even if the crystallinity of the first power transistor 9 subsequently decreases, there is no possibility that it will be turned on. The re-on prevention function of the transistor 9 uses the above-mentioned holding circuit 74 provided to maintain the overcurrent protection state at 111, so the overall circuit configuration is There is no such thing.

Of course, the set state of the holding circuit 74 as described above may vary depending on the temperature. After removing the cause, the 7u power source can be turned on again to return to the reset state.

In the above embodiment, the main or auxiliary "1'. Although a power transistor is used as the conductor switching element, it is also possible to use a power transistor, power GTO, etc. instead.

[Effects of the Invention] According to the present invention, as explained above, by using the 11-conductor switching element for intermittent driving of the wiper motor, it is possible to improve the reliability by κ·1 in terms of contact and life, and Above ゛1-Protection from overcurrent and overvoltage after conductor switching, and ensure that the wiper stops at the standby position. The operating state is canceled inadvertently! j! It is possible to achieve an excellent effect of preventing the situation from occurring without complicating the overall circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention. In the figure, ] is the wiper switch, 2 is the washer switch,
4 is the power line, 5 is the wiper motor, 6 is the fixed position stop 11
switch, 7 is a signal line, 8 is a bomb moder, 9 is a first power transistor (main semiconductor switching element)
, 10 is a second power transistor (assistant conductor switching element), 11 is a sampling resistor (current detection means), 15 is an interval control circuit, 22 is a drive circuit, 24
is an auxiliary ground line, 32 is a brake control circuit, 42 is a washer interlocking circuit, 51 is a first comparison circuit, and 52 is a second
74 is a holding circuit, 85 is a surge protection circuit,
Reference numeral 91 indicates a thermostat (temperature sensor), and 90 indicates an overheat protection circuit.

Claims (1)

[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; and a wiper switch for moving the wiper to a predetermined standby position. A wiper control device comprising: a fixed position stop switch that is switched to a detection state when the wiper switch is switched to an intermittent mode position; is set to the intermittent mode position and is periodically started to operate by an interval control circuit, and the operating state of each cycle is maintained until the fixed position stop switch is switched to the detection state. A drive circuit that turns on the main semiconductor switching element, an auxiliary semiconductor switching element that is turned on when the drive circuit is stopped to short-circuit 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 comparison circuit that outputs a trip signal when the load current detected by the current detection means increases to a predetermined value or more; and a comparison circuit that outputs a trip signal when the comparison circuit outputs the trip signal; a holding circuit that switches to a set state in which the operation is stopped; a temperature sensor that detects the temperature of the main semiconductor switching element; and a holding circuit that forcibly sets the holding circuit when the temperature detected by the temperature sensor exceeds a predetermined value. 1. A wiper control device comprising: an overheat protection circuit that switches the drive circuit to a state and stops the operation of the drive circuit.