JPH1148916A - Wiper driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a wiper driving device as being capable of setting the operating speed of a wiper to any speed and simplifying the structure of a wiper motor. SOLUTION: A wiper driving device has a FET 14 connected between a coil for a wiper motor 12 and a power supply to connect the coil to the power supply with switching operation corresponding to a driving signal, a variable resistor VR 1 (speed signal input means) to input a voltage signal (speed signal) for continuously changing the operating speed of a wiper and an IC 17 (driving signal output means) to output a pulse signal with a pulse width corresponding to the speed signal, as the driving signal for the FET 14, when the wiper is instructed to be operated by a wiper switch 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for driving a wiper provided in a vehicle or the like, and more particularly to a wiper driving device in which the operating speed of the wiper can be changed to an arbitrary speed.

[0002]

2. Description of the Related Art Generally, a wiper driving device provided in a vehicle front window or the like has a circuit configuration as shown in FIG. 3, and basically includes a wiper motor 2 which drives a wiper by a switching operation of a wiper switch 1. The power source is connected to drive the wiper. As the wiper motor 2, a motor having a high-speed winding and a low-speed winding is usually used. The wiper motor 2 has a built-in motor origin detection switch 3.

The two windings of the wiper motor 2 realize two kinds of rotation speeds, high speed and low speed, and the motor origin detection switch 3 always moves the wiper blade (not shown) to a predetermined stop position (not shown). (Normally left end)
This is to detect that the rotating shaft of the wiper motor 2 has returned to the origin position corresponding to the stop position. Hereinafter, a detailed configuration and operation of such a conventional wiper driving device will be described.

As shown in FIG. 3, the wiper motor 2 is
High-speed terminal 2a connected to one coil end of high-speed winding
And a low-speed terminal 2 connected to one end of the low-speed winding
b, and the other coil end of each winding is connected to the ground. When the high-speed winding is energized, it operates at a predetermined high-speed rotation speed, and when the low-speed winding is energized, it operates at a predetermined low-speed rotation speed.

The wiper switch 1 has two sets of three contact type contact portions 1a and 1b having a C terminal (common terminal), an OFF terminal, an H terminal and an L terminal, and these two sets of switches have the same operation. It is linked in accordance with the operation of a unit (not shown). The wiper switch 1 is operated by a driver of the vehicle, for example, in an off state in which each C terminal is connected to an OFF terminal, a high-speed on state in which each C terminal is connected to an H terminal, or each C terminal and L terminal. Is connected to one of the low-speed ON states. FIG. 3 shows the case of the off state.

[0006] One C terminal (C terminal on the side of the contact portion 1a) of the wiper switch 1 is connected to a high speed terminal 2a (coil end of high speed winding) of the wiper motor 2;
One H terminal is connected to a power supply via an ignition switch (not shown) of the vehicle. The other C terminal of the wiper switch 1 (the C terminal on the side of the contact portion 1b) is connected to the low-speed terminal 2b (the coil end of the low-speed winding) of the wiper motor 2, and the other L terminal is connected to the vehicle. Connected to the power supply via the ignition switch. Note that one L terminal and OFF terminal and the other H terminal are in a non-connected state. Further, the other OFF terminal is connected to a C terminal of the motor origin detection switch 3 described later.

Further, the motor origin detecting switch 3 has a terminal C, a terminal N. O terminal (normally open terminal) and N.O. It has a C terminal (normally closed terminal), and in the detection state where the origin position is detected, the C terminal and the N.C. In a non-detection state in which the origin position is not detected, the terminal C and the N.C. The O terminal is connected.

The C terminal of the motor origin detecting switch 3 is connected to the OFF terminal of the contact portion 1b of the wiper switch 1, and the N.C. The O terminal is connected to a power supply via an ignition switch. The C terminal is connected to the ground together with the other coil end of the wiper motor 2.

In the above configuration, when the wiper switch 1 is operated from the off state as shown in FIG. 3 to the low speed on state with the ignition switch turned on and power is supplied, the contact portion of the wiper switch 1 is turned on. A current flows only through the low-speed winding of the wiper motor 2 via the L terminal and the C terminal 1b, and the wiper starts and operates at a low speed. Further, when the wiper switch 1 is operated to be turned on at a high speed, a current flows only through the high-speed winding of the wiper motor 2 via the H terminal and the C terminal of the contact portion 1a of the wiper switch 1, and the wiper operates at a high speed. Operate.

[0010] In the above operating state,
An operating state in which the rotation axis of the wiper motor 2 has left the origin position (that is, a state in which the wiper blade is not at a predetermined stop position).
In, the motor origin detection switch 3 is in a non-detection state,
N. of motor origin detection switch 3 The O terminal is closed.

Therefore, even if the wiper switch 1 is operated and turned off in such a state in which the origin is not detected, the C terminal of the motor origin detection switch 3 and the N.V. O terminal,
And C terminal of contact portion 1b of wiper switch 1 and OFF
A current flows through the low-speed winding of the wiper motor 2 via the line passing through the terminal, and the operation of the wiper (low-speed operation) is continued. Thereafter, when the rotating shaft of the wiper motor 2 returns to the home position (that is, when the wiper blade returns to a predetermined stop position), the motor home position detection switch 3 is in the detection state, and the current path Is cut off and the motor 2 stops.

At this time, one end of the low-speed winding of the wiper motor 2 is connected to the C terminal of the motor origin detecting switch 3 and the N.C. C terminal and contact portion 1b of wiper switch 1
Is connected to the ground through a line passing through the C terminal and the OFF terminal, a back electromotive force is generated, and the wiper motor 2 is regeneratively braked and smoothly stops. In this manner, the wiper blade operates at two speeds, high speed or low speed, by operating the wiper switch 1, so that the wiper blade always returns to the predetermined stop position and stops smoothly regardless of the position where the wiper switch 1 is turned off. Become.

[0013]

In the above-mentioned conventional wiper driving device, the operating speed of the wiper can be adjusted only in two stages, high speed and low speed. There was a problem that the operation speed could not be set. Further, since two windings are required, there is a problem that the structure of the wiper motor is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wiper driving device in which the operating speed of the wiper can be set to an arbitrary speed and the structure of the wiper motor can be simplified.

[0015]

According to one aspect of the present invention, there is provided a wiper driving apparatus comprising: an operation switch for commanding an operation of a wiper; a wiper motor for driving the wiper; An FET connected between the coil and the power supply for connecting the coil and the power supply by a switching operation according to a drive signal; and a speed signal input means for inputting a speed signal for changing the operation speed of the wiper steplessly And drive signal output means for outputting a pulse signal having a pulse width ratio corresponding to the speed signal as a drive signal for the FET when the operation of the wiper is commanded by the operation switch.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing the wiper driving device of the present example. As shown in FIG. 1, the wiper driving device of this embodiment includes a wiper switch 11 (operation switch) having one set of one-contact type switches, a wiper motor 12 having only a high-speed winding, and power supply to the motor 12. An electromagnetic relay 13 and an FET 14, a transistor 15 for driving the electromagnetic relay 13, and ICs 16, 17, and 19 for outputting drive signals for the transistor 15 and the FET 14. In addition, the C terminal and the N.P. The switch 18 has only the O terminal. The ICs 17 and 19 correspond to the drive signal output means of the present invention.

The wiper switch 11 has a C terminal and ON.
The terminal has one of an off state in which the C terminal and the ON terminal are not connected, and an on state in which the C terminal and the ON terminal are connected. FIG. 1 shows the case of the off state. The C terminal of the wiper switch 11 is connected to the ground, and the ON terminal is connected to the input terminal of the IC 16.

The electromagnetic relay 13 includes an exciting coil 13a,
C terminal, N. O terminal and N. Contact part 13 having C terminal
b, and when the excitation coil 13a is not energized, the C terminal and the N.N. When the terminal C is connected and the excitation coil 13a is energized, the terminal C is connected to the terminal N. The O terminal is connected. The C terminal of the electromagnetic relay 13 is connected to one end of a motor coil (high-speed winding) of the wiper motor 12. The O terminal is connected to the source terminal of the FET 14, and the N.O. C
The terminal is connected to the ground. One end of the exciting coil 13a is connected to a power supply via an ignition switch, and the other end of the exciting coil 13a is connected to the transistor 1
5 is connected to the ground.

The FET 14 is a so-called field effect transistor. In this case, for example, a power MOSFET (Metal Oxide Semiconductor) capable of switching a large current circuit is used.
torField Effect Transistor) is used.

In this case, the FET 14 is of an N-channel type, and when the gate terminal voltage becomes H level, conduction between the source and the drain is established. In this case, the drain terminal
It is connected to a power supply via an ignition switch, and the source terminal is connected to the N.V. of the electromagnetic relay 13 as described above. Connected to O terminal. The gate terminal is connected to the output terminal of the IC 17 via an IC 19 (charge pump circuit), and the output signal (drive signal) of the IC 17 causes this FET to operate.
14 is driven to exhibit a switching function.

As shown in FIG. 1, a coil L and a diode D are provided between the drain terminal and the source terminal of the FET 14.
Are connected in series, and a capacitor C2 is connected between the connection point between the coil L and the diode D and the ground. The coil L, the diode D, and the capacitor C2 are for applying regenerative power to the motor 12 in an off state when the FET 14 is turned on and off.

The FET 14 may be of a P-channel type, in which case the IC 19
(Charge pump circuit) is unnecessary.

The IC 16 is a NAND circuit having two input terminals (for example, a one-chip IC).
The voltage of the ON terminal of the wiper switch 11 and the voltage of the C terminal of the motor origin detection switch 18 are input signals, and the drive signal of the transistor 15 and the enable (e
a) signal is output. in this case,
If the voltage of the ON terminal of the wiper switch 11 or the voltage of the C terminal of the motor origin detection switch 18 is at the ground level, the output signal of the IC 16 is turned on, and the transistor 15 is turned on (energized state). At the same time, an enable signal is input to an E terminal (described later) of the IC 17.

The IC 17 is a voltage-frequency converter (for example, a one-chip IC), and includes a voltage input terminal (f terminal), a voltage input terminal (Vi terminal), and an output terminal (out terminal). , An enable signal input terminal (hereinafter, referred to as an E terminal). This IC 17 is a square wave (pulse signal) having a frequency f determined by the resistor R1 and the capacitor C1 connected to the voltage input terminal (f terminal) when the voltage of the E terminal is turned on and the enable signal is being input. The output voltage is a drive signal applied to the gate terminal of the FET 14 described above.

The voltage adjusted by the variable resistor VR1 is input to the voltage input terminal (Vi terminal) of the IC 17, and the pulse width of the output voltage waveform of the out terminal is adjusted according to this voltage. The configuration is such that the ratio m continuously changes in the range of 0 to 100%. It should be noted that the pulse width ratio m here is a time ratio in which the signal is on. FIG. 2 is a diagram showing an output voltage waveform of the IC 17 (a waveform of a drive signal of the FET 14).
The period indicated by the symbol T is the period corresponding to the oscillation frequency f (T =
1 / f), and the symbol t indicates the pulse width (time when the voltage is at the high level). In this case, the pulse width ratio m
[%] Is m = t / T × 100.

The oscillating frequency f of the IC 17 may be a general oscillating frequency of this type of circuit (that is, about 20 Khz which is higher than the audible frequency and does not cause radio interference). Here, the variable resistor VR1 corresponds to the speed signal input means of the present invention, and the voltage input to the voltage input terminal (Vi terminal) of the IC 17 is a voltage for continuously changing the operation speed of the wiper. It corresponds to the speed signal of the invention.

The IC 19 is a charge pump circuit (in this case, a one-chip IC).
Output voltage waveform of C17 (drive signal waveform of FET14)
And boosts the voltage of the drive signal applied to the gate terminal of the FET 14 above the voltage of the drain terminal. Note that the provision of such a charge pump circuit has an advantage that the switching operation of the FET 14 can be performed more reliably and completely.

Next, the motor origin detecting switch 18
Terminal and N. It has an O terminal, and in a detection state where the origin position is detected, the C terminal and the N.N. In the non-detection state where the O terminal is not connected and the origin position is not detected, the C terminal and the N.N. The O terminal is connected. The C terminal of the motor origin detection switch 18 is connected to the input terminal of the IC 16 as described above. The O terminal is connected to the ground together with the other end of the motor coil of the wiper motor 12.

In the driving device having the above-described circuit configuration, the electromagnetic relay 13 and the FET 14 are driven by the turning-on operation of the wiper switch 1 or the non-detection operation of the motor origin detecting switch 18, whereby the current of the coil of the wiper motor 2 is supplied. Flows and the wiper operates. And at this time, IC
FETs output from 17, 19 (drive signal output means)
The drive signal 14 is a pulse signal having a pulse width ratio according to the voltage (speed signal) input by the variable resistor VR1 (speed signal input means). For this reason, the voltage applied to the motor 12 is changed by the voltage (speed signal) into a so-called P
WM modulation (pulse width modulation) is performed, and the operating speed of the wiper becomes a speed corresponding to the voltage (speed signal). Therefore, the wiper operation speed is continuously variable, and furthermore, the same origin return operation as the conventional one is realized.

That is, when the wiper switch 11 is operated to change from the off state to the on state, the wiper switch 11 is turned on.
One of the inputs of the IC 16 goes to the ground level via the C terminal and the ON terminal, so that the output signal of the IC 16 is turned on, the transistor 15 is activated, and the electromagnetic relay 13 is activated. On the other hand, when the output signal of the IC 16 is turned on, the E terminal of the IC 17 is turned on. Therefore, the pulse signal (drive signal) shown in FIG. 2 is output from the IC 17, and the pulse signal is boosted by the IC 19. Then, it is applied to the gate terminal of the FET 14. For this reason,
In response to the pulse signal, the FET 14 turns on and off at the above-described cycle f.

At this time, when the pulse signal (drive signal) output from the IC 17 is on, the state between the drain and source of the FET 14, the C terminal of the electromagnetic relay 13 and the N.C. A power supply voltage is applied to the coil of the wiper motor 2 by a line passing through the O terminal. When the pulse signal (drive signal) output from the IC 17 is off, regenerative power is applied to the coil of the wiper motor 2 via the above-described diode D, capacitor C2, and coil L.

For this reason, the wiper motor 2 is eventually
The operation is performed at a speed proportional to the pulse width ratio of the pulse signal output from 17, and the operation speed of the wiper is also proportional to this pulse width ratio. Therefore, if the driver or the like operates the variable resistor VR1 (speed signal input means), the operating speed of the wiper can be adjusted to an arbitrary size at any time.

In the operating state where the rotation axis of the wiper motor has left the origin position, the motor origin detection switch 18
Is in a non-detection state, and the N.O. The O terminal is connected to the C terminal. For this reason,
In such a non-detection state of the origin, the wiper switch 11
Is turned off, the output signal of the IC 16 is also turned on and the electromagnetic relay 13 is turned on because the C terminal of the motor origin detection switch 18 is connected to the ground.
And the on / off operation of the FET is continued, and the operation of the wiper at the set speed is continued.

Thereafter, when the rotation axis of the wiper motor returns to the origin position, the motor origin detection switch 18
Is in the detection state, the electromagnetic relay 13 and the FET 14 are deactivated, and the motor 12 stops. In this case,
One end of the motor coil of the wiper motor 12 is connected to the C terminal of the electromagnetic relay 13 and the N.V. Since the wiper motor 12 is connected to the ground via the C terminal, the wiper motor 12 is also regeneratively braked and stops smoothly.

Therefore, according to the wiper driving device of the present embodiment, the wiper can be operated in the same manner as the conventional one while the wiper motor 12 has a simple structure having only the high-speed winding, and the operation speed of the wiper can be set to an arbitrary value. And can be adjusted steplessly. Therefore, the driving operation of the vehicle at the time of rain or the like becomes more comfortable, and the size and cost of the wiper motor can be reduced.

The present invention is not limited to the above-described embodiment, and may have various aspects. For example, the speed signal input means of the present invention is not limited to manual operation by a driver or the like, and a processing means such as a microcomputer obtains and outputs an optimum speed signal according to a detection value of a raindrop sensor or a vehicle speed sensor. The configuration may be as follows. Further, the drive signal output means of the present invention is not limited to the voltage-frequency converter as described above, but may be constituted by, for example, a one-chip microcomputer.

[0037]

According to the wiper driving device of the present invention, when the operation of the wiper is instructed by the operation switch, the drive signal output means outputs a pulse having a pulse width ratio corresponding to the speed signal input by the speed signal input means. The signal is output as a drive signal for the FET. Then, according to this drive signal, F
The ET is turned on and off, and the power supply voltage is intermittently applied to the coil of the wiper motor. For this reason, the voltage applied to the wiper motor is controlled by the speed signal so-called PW
As a result, the wiper operates at an operation speed corresponding to the speed signal.

Therefore, without using a complicated and expensive motor having a plurality of windings according to the operating speed as the wiper motor, the operating speed of the wiper can be varied, and furthermore, the speed signal that changes steplessly can be used. The operation speed can be adjusted arbitrarily and steplessly. Therefore, the driving operation of the vehicle at the time of rain or the like becomes more comfortable, and the size and cost of the wiper motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an example of a wiper driving device.

FIG. 2 is a diagram showing a drive signal of an FET of the device.

FIG. 3 is a circuit diagram showing a conventional wiper driving device.

[Explanation of symbols]

 Reference Signs List 11 Wiper switch (operation switch) 12 Wiper motor 17, 19 IC (drive signal output means) 14 FET VR1 Variable resistor (speed signal input means)

Claims (1)

[Claims] An operation switch for instructing operation of a wiper, a wiper motor for driving a wiper, and a coil connected to a coil of the wiper motor and a power supply, and a switching operation according to a drive signal causes the coil to operate. An FET for connecting a power source, speed signal input means for inputting a speed signal for continuously changing the operating speed of the wiper, and when the operation of the wiper is instructed by the operation switch, the speed signal corresponds to the speed signal. And a drive signal output means for outputting a pulse signal having a pulse width ratio as a drive signal for the FET.