JP2013163476A - Wiper drive apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiper drive apparatus configured to improve reliability of an auto-stop signal.SOLUTION: A terminal 241 of a cam switch 24 is connected to a terminal 240 to be connected to a ground terminal G20 when a wiper is located at a predetermined stop position, and is connected to a terminal 242 to be connected to a battery 7 via an ignition switch 6 when the wiper is located at a position other than the predetermined stop position. When the wiper is driven at an intermittent mode and is located at a position other than the predetermined stop position, a wiper drive apparatus 10 turns off a p-type MOSFET 32 which has been turned on when the wiper starts to move, and turns on an n-type MOSFET 34. A current for driving a wiper motor 22 flows to the wiper motor 22 through the cam switch 24, the n-type MOSFET 34 connected to the terminal 241, a relay 35, and a wiper switch 8. The reliability of an auto-stop signal indicating that the wiper is located at the predetermined position can be improved.

Description

  The present invention relates to a wiper driving device.

  2. Description of the Related Art Conventionally, a wiper driving device that drives a wiper that wipes raindrops attached to a windshield of a vehicle is known. The wiper drive device determines, for example, the wiper wiping speed and the time for the wiper to stop at a predetermined stop position in accordance with the wiper drive mode selected by the vehicle driver. In particular, when the driver selects an “intermittent mode” in which the time for the wiper to stop at a predetermined stop position can be arbitrarily set, the wiper driving device controls the timing of supplying a current for driving the wiper motor by the semiconductor circuit. Patent Document 1 describes a wiper control device in which when a wiper drive is stopped in an intermittent mode, a cam switch linked to the wiper drive connects a ground terminal of the motor and an FET drive circuit.

JP-A-5-58250

  However, in the wiper control device described in Patent Document 1, since the FET drive circuit drives the brake FET in accordance with the switching of the cam switch, the process of controlling the intermittent mode of the wiper becomes complicated. Further, the cam switch is a switch through which a current for driving the wiper motor normally flows. However, a large current for driving the wiper motor does not flow only by connecting the ground terminal of the motor and the FET drive circuit. For this reason, the reliability of the auto stop signal that informs that the wiper transmitted by the cam switch is at a predetermined stop position is lowered.

  An object of the present invention is to provide a wiper driving device capable of improving the reliability of an auto stop signal.

According to the first aspect of the present invention, the wiper driving device drives the wiper that wipes raindrops on the windshield of the vehicle. The wiper drive device includes a wiper motor, a wiper switch, a wiper motor control circuit, and a cam switch. The wiper motor reciprocates the wiper between a predetermined stop position and a maximum wiping position. The wiper motor control circuit is electrically connected to a power supply source of the vehicle, a wiper motor, and a wiper switch capable of selecting a driving mode of the wiper. The wiper motor control circuit controls the driving of the wiper motor based on the wiper driving mode selected by the wiper switch. The wiper drive mode includes at least an intermittent mode in which the time for the wiper to stop at a predetermined stop position can be set. The cam switch switches the first terminal to the ground when the wiper is at a predetermined stop position, or electrically connects the first terminal to the power supply source when the wiper is at a position other than the predetermined stop position.
The wiper motor control circuit includes an n-type MOSFET, a p-type MOSFET, and a control unit. The source side terminal of the n-type MOSFET is connected to the first terminal of the cam switch. Further, the drain side terminal of the n-type MOSFET is connected to a driving terminal of a wiper motor that receives power supplied from a power supply source. The source side terminal of the p-type MOSFET is electrically connected to a power supply source. The drain side terminal of the p-type MOSFET is connected to the drive terminal.

  The control unit is electrically connected to the wiper switch, the n-type MOSFET, and the p-type MOSFET, and controls on / off of the n-type MOSFET and the p-type MOSFET. The control unit performs the following control when the intermittent mode is selected as the wiper drive mode with the wiper switch. When the intermittent mode is selected, the n-type MOSFET is turned on. When the wiper starts moving from a predetermined stop position, the n-type MOSFET is turned off and then the p-type MOSFET is turned on. When the wiper is at a position other than a predetermined stop position, the p-type MOSFET is turned off and then the n-type MOSFET is turned on.

  In the wiper drive device according to the first aspect, when the intermittent mode is selected as the wiper drive mode and the wiper is in a position other than the predetermined stop position, the cam switch connects the first terminal to the power supply source. Further, the drain side terminal of the n-type MOSFET is connected to the driving terminal of the wiper motor. Thereby, when the wiper is driven in the intermittent mode and the n-type MOSFET is in the ON state, a current for driving the wiper motor flows through the cam switch. When the wiper returns to the predetermined stop position in the intermittent mode, no current flows through the wiper motor by switching the cam switch, and the source side terminal of the n-type MOSFET is grounded. At this time, since the reverse current generated by the wiper motor flows to the ground via the n-type MOSFET, the drive of the wiper is braked and stopped at a predetermined stop position. Thereby, while the wiper is driven in the intermittent mode, a current for driving the wiper motor flows via the cam switch. On the other hand, when the wiper stops in the intermittent mode, the current does not flow to the wiper motor due to the switching of the cam switch. Therefore, in the wiper drive device according to the first aspect, since the current for driving the wiper motor flows through the cam switch, the reliability of the auto stop signal transmitted from the cam switch can be improved.

  Further, when the wiper is stopped in the intermittent mode, current does not flow to the wiper motor by switching the cam switch, so that it is not necessary to control the on / off state of the n-type MOSFET in accordance with the stop of the wiper. In addition, when the wiper is started in the intermittent mode, the p-type MOSFET that is turned on is also turned off while the wiper is being driven. Therefore, the on / off state of the p-type MOSFET is not controlled when the wiper is stopped. May be. Therefore, when driving the wiper in the intermittent mode, the control process of the n-type MOSFET and the p-type MOSFET can be simplified.

It is a whole schematic diagram of a wiper control device using a wiper drive device by one embodiment of the present invention. It is a circuit diagram of the wiper drive device by one embodiment of the present invention. FIG. 3 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current flows when the wiper is driven in a high-speed mode. FIG. 3 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current flows when the wiper is driven in a low speed mode. FIG. 3 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current flows when the wiper is driven in an automatic mode. 6 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current different from that in FIG. 5 flows when the wiper is driven in an automatic mode. FIG. FIG. 7 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current different from that in FIGS. 5 and 6 flows when the wiper is driven in an automatic mode. FIG. 8 is a circuit diagram of a wiper driving device according to an embodiment of the present invention, and is a circuit diagram illustrating a path through which a current different from that in FIGS. 5 to 7 when driving the wiper in an automatic mode. 4 is a time chart showing an on / off state of a MOSFET and an energization state of an external terminal when the wiper of the wiper driving device according to the embodiment of the present invention is driven in an automatic mode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(One embodiment)
A wiper control device including a wiper driving device according to an embodiment of the present invention is shown in FIG. The wiper control device 2 is mounted on a vehicle and controls driving of the wiper 5 that wipes raindrops attached to the windshield 4 on the front surface of the passenger compartment.

First, the overall configuration of the wiper control device 2 will be described.
The wiper control device 2 includes a wiper drive device 10 and a raindrop detection device 9. The wiper driving device 10 and the raindrop detection device 9 are supplied with electric power of, for example, a voltage of 12 [V] from the vehicle battery 7 as the “power supply source” via the ignition switch 6 of the vehicle.

  The wiper drive device 10 includes a wiper switch 8, a wiper motor control circuit 30, and a wiper motor drive unit 20.

  The wiper switch 8 is installed at a driver's seat in the passenger compartment, and selects the driving mode of the wiper 5, that is, the “wiping speed” and “wiping interval” of the wiper 5. The “wiping speed” of the wiper 5 here refers to the moving speed of the wiper 5 when the wiper 5 wipes the windshield 4. Further, the “wiping interval” of the wiper 5 means that the wiper 5 is moved from the predetermined stop position on the windshield 4 shown in FIG. 1 to the maximum wiping position and then returned to the predetermined stop position again. When driving is defined as one cycle, it means the time for stopping at a predetermined stop position from the end of one cycle to the start of the next cycle. For example, when the wiper 5 is driven in a high speed mode or a low speed mode, which will be described later, the wiping interval of the wiper 5 is set to the shortest time in the wiper 5 drive mode. The wiper switch 8 switches connection of a plurality of external terminals connected to the wiper motor control circuit 30 or the wiper motor drive unit 20 according to the drive mode of the wiper 5 selected by the driver.

  The wiper motor control circuit 30 controls the driving of the wiper motor drive unit 20 based on the terminal connected by the wiper switch 8 and the signal output from the raindrop detection device 9. Specifically, when the wiper switch 8 connects an external terminal so that the driving mode of the wiper 5 is the low speed mode or the high speed mode, the wiper motor driving unit 20 is driven so as to realize one of the wiping speeds. When the wiper switch 8 connects an external terminal so that the driving mode of the wiper 5 becomes the automatic mode, the wiping speed and the wiping interval of the wiper 5 are set based on a signal output from the raindrop detection device 9. The wiper motor control circuit 30 drives the wiper motor drive unit 20 so as to realize the set wiping speed and wiping interval. When the wiper switch 8 connects an external terminal so that the drive mode of the wiper 5 is set to the stop mode, no current flows through the wiper motor drive unit 20, and the wiper 5 maintains the stopped state. The “automatic mode” here refers to driving the wiper 5 so as to realize the wiping speed and wiping interval of the wiper 5 automatically calculated by the microcomputer 38 to be described later based on the amount of raindrops on the windshield 4. Drive mode.

  The wiper motor drive unit 20 is connected to the wiper 5 via the connecting unit 3. The wiper motor drive unit 20 generates a rotational motion by the electric power supplied from the battery 7. The generated rotational motion is converted into a reciprocating swing motion of the wiper 5 by the connecting portion 3.

  The raindrop detection device 9 is mounted on the interior side of the windshield 4 and detects the amount of raindrops adhering to the outside of the windshield 4. The raindrop detection device 9 is arranged in such a manner that the projection area onto the windshield 4 is within the area wiped by the wiper 5 on the windshield 4.

  Next, the circuit of the wiper driving device 10 will be described with reference to FIG. FIG. 2 also shows the ignition switch 6, the battery 7, and the raindrop detection device 9 that are electrically connected to the wiper driving device 10.

  The wiper switch 8 is a contact switch that switches a contact to be electrically connected in accordance with a driving mode of the wiper 5 selected by the driver. In the present embodiment, the high-speed mode (“HIGH” in FIG. 2) for continuously driving the wiper 5 at high speed, the low-speed mode (“LOW” in FIG. 2) for continuously driving the wiper 5 at low speed, An automatic mode (“AUTO” in FIG. 2) for driving the wiper 5 based on the amount of raindrops on the windshield 4 to be detected, and a stop mode (“OFF” in FIG. 2) for stopping the wiper 5 drive. The four types of drive modes can be selected.

  The external terminal D8 of the wiper switch 8 is connected to the power supply terminal D20 of the wiper motor drive unit 20 and the power supply terminal D30 of the wiper motor control circuit 30, and is also connected to one terminal 61 of the ignition switch 6. The other terminal 62 of the ignition switch 6 is connected to the positive electrode of the battery 7. The negative electrode of the battery 7 is grounded.

  The external terminal H8 of the wiper switch 8 is connected to the external terminal H20 of the wiper motor driving unit 20 and the external terminal H30 of the wiper motor control circuit 30. The external terminal L8 of the wiper switch 8 is connected to the external terminal L20 of the wiper motor drive unit 20. The external terminal S8 of the wiper switch 8 is connected to the external terminal L30 of the wiper motor control circuit 30. The external terminal C8 of the wiper switch 8 is connected to the external terminal C30 of the wiper motor control circuit 30. The external terminal W8 of the wiper switch 8 is grounded via the external terminal W30 of the wiper motor control circuit 30 and the ground terminal G30.

  The wiper motor control circuit 30 includes a p-type MOSFET 32, an n-type MOSFET 34, a relay 35, a booster circuit 36, a microcomputer 38, and the like.

  The p-type MOSFET 32 connects the source side terminal PS1 to one terminal 61 of the ignition switch 6 through the power supply terminal D30. The drain side terminal PD1 is connected to the terminal RY0 of the relay 35 and the drain side terminal ND1 of the n-type MOSFET 34. The gate side terminal PG1 is connected to one terminal 61 via a resistor R1 and is connected to a collector side terminal of the transistor T1 electrically connected to the microcomputer 38. The p-type MOSFET 32 has its on / off state controlled by the microcomputer 38 switching on / off of the transistor T1, and connects the external terminal D30 and the terminal RY0 when in the on state.

  The n-type MOSFET 34 connects the source side terminal NS1 to the microcomputer 38 and also connects to the terminal 241 of the cam switch 24 included in the wiper motor driving unit 20 via the external terminals S30 and S20. The drain side terminal ND1 is connected to the terminal RY0 and the drain side terminal PD1 of the p-type MOSFET 32. The gate side terminal NG1 is electrically connected to the booster circuit 36 via the resistor R2, and is connected to the source side terminal NS1 via the diode D1. When the voltage boosted by the booster circuit 36 and the voltage between the external terminal S30 and the source side terminal NS1 are applied to the gate side terminal NG1, the n-type MOSFET 34 connects the external terminal S30 and the terminal RY0 of the relay 35. Connecting. At this time, the resistor R2 steps down the voltage boosted by the booster circuit 36 to about the rated voltage of the n-type MOSFET 34.

  The relay 35 switches the terminal RY0 to one terminal RY1 or the other terminal RY2 by the microcomputer 38 switching on and off of the transistor T2. One terminal RY1 is connected to the external terminal L30. The other terminal RY2 is connected to the external terminal H30.

  The booster circuit 36 is electrically connected to the microcomputer 38 and is electrically connected to one terminal 61 of the ignition switch 6 via the external terminal D30. When the ignition switch 6 is in the on state, the booster circuit 36 boosts the voltage of the electric power supplied from the battery 7 to the booster circuit 36 in accordance with a signal from the microcomputer 38. The booster circuit 36 is grounded via the ground terminal G30.

  The microcomputer 38 is a small computer having a CPU as arithmetic means and ROM and RAM as storage means. The microcomputer 38 performs various processes by the CPU according to various programs stored in the ROM. A signal corresponding to the amount of raindrops attached to the vehicle exterior side of the windshield 4 detected by the raindrop detection device 9 is input to the microcomputer 38 via the external terminal R30. Further, when the driver selects the automatic mode with the wiper switch 8, the microcomputer 38 is grounded via the external terminal C30, the wiper switch 8, the external terminal W30, and the ground terminal G30. At this time, the microcomputer 38 sets the wiping speed and wiping interval of the wiper 5 based on the signal input from the raindrop detection device 9. For example, when the amount of raindrops on the windshield 4 is less than a predetermined amount, the wiping speed is set slower or the wiping interval is set longer. Further, when the amount of raindrops on the windshield 4 is larger than a predetermined amount, the wiping speed is set fast or the wiping interval is set short. The microcomputer 38 controls the driving of the p-type MOSFET 32, the n-type MOSFET 34, the relay 35, and the booster circuit 36 based on the set wiping speed and wiping interval of the wiper 5. The microcomputer 38 corresponds to a “control unit” recited in the claims.

  The wiper motor drive unit 20 includes a wiper motor 22 and a cam switch 24.

  The wiper motor 22 has two terminals 221 and 222 that receive the power of the battery 7 in addition to the terminal 220 that is grounded via the ground terminal G20. The terminal 221 is connected to the external terminal L20. The terminal 222 is connected to the external terminal H20. The wiper motor 22 has a coil, and a high-speed brush for high-speed driving connected to the terminal 222 and a low-speed brush for low-speed driving connected to the terminal 221 are in contact with the coil. The wiper motor 22 can change the rotational speed of the rotational motion that is output depending on the difference in terminals that receive power. The terminal 221 corresponds to a “low speed driving terminal” recited in the claims. The terminal 222 corresponds to a “high-speed driving terminal” recited in the claims.

  The cam switch 24 switches the connection between the terminal 241 connected to the external terminal S20 and the terminal 240 connected to the ground terminal G20 or the connection to the terminal 242 connected to one terminal 61 of the ignition switch 6. The switching of the connection by the cam switch 24 is based on the position of the wiper 5 on the windshield 4. Specifically, when the wiper 5 is at a predetermined stop position on the windshield 4 (see FIG. 1), the terminal 241 is connected to the terminal 240. On the other hand, when the wiper 5 is at a position other than the predetermined stop position on the windshield 4, the terminal 241 is connected to the terminal 242. The terminal 241 corresponds to a “first terminal” recited in the claims.

  Next, the operation of the wiper driving device 10 of the present embodiment will be described based on FIGS. 2 to 9 when the wiper 5 is driven when the ignition switch 6 is in the ON state. In addition, the dotted line in FIGS. 3-8 shows the flow of an electric current.

  When the wiper switch 8 selects the driving mode of the wiper 5 to be the stop mode, the external terminal L8 and the external terminal S8 are connected in the wiper switch 8. In the cam switch 24, the terminal 241 and the terminal 240 are connected. Further, since the microcomputer 38 does not output a signal for turning on the transistor T1, the p-type MOSFET 32 is in the off state. Thereby, since no current flows through the wiper motor 22, the wiper 5 is not driven.

  Next, when the wiper switch 8 selects the wiper 5 drive mode to be the high speed mode, the wiper switch 8 connects the external terminal D8 and the external terminal H8. At this time, as shown in FIG. 3, the power supplied by the battery 7 is supplied from the terminal 222 to the wiper motor 22 via the ignition switch 6 and the external terminals D8, H8, and H20. As a result, the wiper motor 22 generates a rotational motion and the wiper 5 is driven. Since the terminal 222 is connected to the high speed brush of the wiper motor 22, the wiper driving device 10 continuously drives the wiper 5 at a high speed until a driving mode other than the high speed mode is selected by the wiper switch 8.

  Next, when the wiper switch 8 is selected so that the driving mode of the wiper 5 is the low speed mode, the wiper switch 8 connects the external terminal D8 and the external terminal L8. At this time, as shown in FIG. 4, the power supplied by the battery 7 is supplied from the terminal 221 to the wiper motor 22 via the ignition switch 6 and the external terminals D8, L8, and L20. As a result, the wiper motor 22 generates a rotational motion and the wiper 5 is driven. Since the terminal 221 is connected to the low speed brush of the wiper motor 22, the wiper driving device 10 continuously drives the wiper 5 at a low speed until a driving mode other than the low speed mode is selected by the wiper switch 8.

  Next, the operation of the wiper driving device 10 when the wiper switch 8 is selected to set the driving mode of the wiper 5 to the automatic mode will be described with reference to the time chart of FIG. FIG. 9A shows a time chart of the p-type MOSFET 32 in the on / off state. FIG. 9B shows a time chart of the on / off state of the n-type MOSFET 34. FIG. 9C shows a time chart of the energized state of the external terminal S20. FIG. 9D shows a time chart of the energized state of the external terminal L20.

  When the wiper switch 8 selects the driving mode of the wiper 5 to be the automatic mode (time t0 in FIG. 9), the wiper switch 8 connects the external terminal L8 and the external terminal S8, and the external terminal C8. The external terminal W8 is connected. The microcomputer 38 detects that the driver has selected the automatic mode by grounding the external terminal C30. At this time, as shown in FIG. 5, the microcomputer 38 outputs a signal for applying a voltage to the gate terminal NG <b> 1 to the booster circuit 36. In the booster circuit 36, the voltage supplied from the battery 7 is boosted, for example, twice, and applied to the gate side terminal NG1 via the resistor R2. As a result, the n-type MOSFET 34 is turned on, and energization is possible between the external terminal S30 and the terminal RY0 of the relay 35. At time t0, since the wiper 5 is at a predetermined stop position, the terminal 241 and the terminal 240 are connected in the cam switch 24. For this reason, as shown in FIG. 9, the external terminals S <b> 20 and L <b> 20 are not connected to the battery 7, and no power is supplied to the wiper motor 22.

  Next, before time t2 in FIG. 9 when driving of the wiper 5 is started based on the signal output from the raindrop detection device 9, the microcomputer 38 signals the booster circuit 36 to finish applying the voltage to the gate side terminal NG1. Is output. As a result, the booster circuit 36 finishes applying the voltage to the gate-side terminal NG1, so that the n-type MOSFET 34 is turned off (time t1 in FIG. 9).

  Subsequently, the microcomputer 38 turns on the transistor T1 as shown in FIG. The voltage of the power supplied from the battery 7 is applied to the gate terminal PG1 via the resistor R1, and the p-type MOSFET 32 is turned on (time t2 in FIG. 9). Thereby, the external terminal D30 and the terminal RY0 are connected. The electric power supplied from the battery 7 is supplied to the wiper motor 22 via the ignition switch 6, the p-type MOSFET 32, the terminals RY 0 and RY 1, the external terminals L 30, S 8, L 8, L 20, and the terminal 221. Thereby, the wiper 5 starts low speed driving. If the raindrop detection device 9 detects that the amount of raindrops on the windshield 4 is greater than a predetermined amount, the microcomputer 38 turns on the transistor T2 and switches the terminals RY0 and RY2 of the relay 35 to be connected. At this time, the power supplied by the battery 7 is supplied to the wiper motor 22 via the ignition switch 6, the p-type MOSFET 32, the relay 35, the external terminals H30 and H20, and the terminal 222. As a result, the wiper 5 starts high-speed driving. At time t2, since the wiper 5 is still in the predetermined stop position, the terminal 241 and the terminal 240 are connected. Further, after time t2, when the wiper 5 is in a position other than the predetermined stop position, the terminal 241 and the terminal 242 are connected, but the n-type MOSFET 34 is in the off state, so that current flows through the cam switch 24. Absent.

  Next, as shown in FIG. 9, after the wiper 5 starts to be driven, the p-type MOSFET 32 is turned off after a predetermined time (between time t3 and time t2 in FIG. 9) has passed (FIG. 9). T3). Specifically, the microcomputer 38 turns off the transistor T1, so that no voltage is applied to the gate terminal PG1, so that the p-type MOSFET 32 is turned off. At this time, the wiper 5 is located at a position other than a predetermined stop position and is driven on the windshield 4.

  After the p-type MOSFET 32 is turned off, the microcomputer 38 outputs a signal for applying a voltage to the gate-side terminal NG1 to the booster circuit 36. A voltage obtained by adding the voltage of the power supplied from the battery 7 via the cam switch 24 to the voltage output from the booster circuit 36 is applied to the gate side terminal NG1 of the n-type MOSFET 34, and the n-type MOSFET 34 is turned on. (Time t4 in FIG. 9). Thereby, as shown in FIG. 7, the electric power supplied from the battery 7 is the ignition switch 6, the external terminal D20, the cam switch 24, the external terminals S20 and S30, the n-type MOSFET 34, the relay 35, the external terminals L30, S8, and L8. , L20, and the terminal 221 to be supplied to the wiper motor 22. Thereby, the low-speed drive of the wiper 5 is maintained. At this time, a current flows through the n-type MOSFET 34 in the direction from the source-side terminal NS1 to the drain-side terminal ND1, that is, in the reverse direction. When the raindrop detection device 9 detects that the amount of raindrops on the windshield 4 is larger than a predetermined amount, the wiper 5 is driven at a high speed by switching the connection terminal at the relay 35.

Next, when the wiper 5 that drives the windshield 4 returns to the vicinity of a predetermined stop position via the maximum wiping position, the cam switch 24 connects the terminal 241 and the terminal 242 as shown in FIG. Is switched to the connection between the terminal 241 and the terminal 240. At this time, the reverse current output from the terminal 221 or the terminal 222 passes through the wiper switch 8, the relay 35, the drain side terminal ND1 of the n-type MOSFET 34, the source side terminal NS1, and the cam switch 24 from the terminal 241 to the terminal 240. And flows to the ground (time t5 in FIG. 9). For reference, FIG. 8 shows a current path when a reverse current is output from the terminal 221. Thereby, the brake is applied to the rotation of the wiper motor 22 and the rotation of the wiper motor 22 is stopped. After the rotation of the wiper motor 22 is completely stopped, the wiper driving device 2 maintains the n-type MOSFET 34 in the ON state as shown in FIG. 5 (time t6 in FIG. 9).
When the automatic mode is selected as the driving mode of the wiper 5 by the wiper switch 8, the wiper driving device 10 uses the current shown in FIGS. 5 to 8 according to the amount of raindrops on the windshield 4 detected by the raindrop detecting device 9. The wiper 5 is driven by repeating the above flow.

  In the wiper drive device 10 of one embodiment, when the wiper 5 is driven in the automatic mode, a current flows to the wiper motor 22 via the cam switch 24 and the n-type MOSFET 34. When the wiper 5 stops in the automatic mode, the cam switch 24 switches the connection between the terminal 241 and the terminal 242 to the connection between the grounded terminal 240 and the terminal 241. At this time, since the reverse current generated in the wiper motor 22 flows to the ground via the wiper switch 8, the n-type MOSFET 34, and the cam switch 24, the drive of the wiper 5 is braked and stopped at a predetermined stop position. Therefore, when the wiper 5 is driven in the automatic mode, a current for driving the wiper motor 22 flows through the cam switch 24, and the reliability of the auto stop signal transmitted by switching the cam switch 24 can be improved.

Further, when the wiper 5 is stopped in the automatic mode, the current does not flow to the wiper motor 22 by switching the cam switch 24. Thereby, it is not necessary to control the on / off state of the n-type MOSFET 34 when the wiper 5 is stopped.
Further, the p-type MOSFET 32 that is turned on when the wiper 5 is started in the automatic mode does not affect the driving of the wiper 5 even when the wiper 5 is being driven. This is because when the n-type MOSFET 34 is turned on after the p-type MOSFET 32 is turned off, current flows to the wiper motor 22 via the cam switch 24 connecting the terminal 242 and the terminal 241 and the n-type MOSFET 34. It is. Thereby, when the wiper 5 is stopped in the automatic mode, it is not necessary to control the on / off state of the p-type MOSFET 32. Therefore, when the wiper 5 is stopped in the automatic mode, it is not necessary to perform on / off control of the n-type MOSFET 34 and the p-type MOSFET 32, and the control processing of the n-type MOSFET 34 and the p-type MOSFET 32 can be simplified.

  In the wiper drive device 10 of one embodiment, when the high speed mode or the low speed mode is selected by the wiper switch 8, the battery 7 and the wiper motor 22 are directly connected. That is, when the wiper 5 is driven in the high speed mode or the low speed mode, the current does not pass through the wiper motor control circuit 30. Thereby, even when the wiper motor control circuit 30 breaks down, the wiper 5 can be driven in the high speed mode or the low speed mode.

  A conventional wiper driving device is provided with a diode for preventing backflow in order to prevent reverse current generated by the motor from flowing into the semiconductor element when the wiper is stopped in the automatic mode. However, when the wiper is driven, a voltage loss due to the diode occurs, and a sufficient wiping speed of the wiper cannot be obtained. In the wiper drive device 10 of the embodiment, when the wiper 5 is stopped in the automatic mode, the reverse current generated by the wiper motor 22 flows from the drain side terminal ND1 on the drain side of the n-type MOSFET 34 to the source side terminal NS1, and the cam switch 24 to the ground. That is, since a current flows through the n-type MOSFET 34 in the forward direction, the n-type MOSFET 34 is less likely to be broken. Thereby, since it is not necessary to provide the diode for backflow prevention, the voltage loss by the backflow prevention diode can be eliminated, and a sufficient wiping speed of the wiper 5 can be obtained.

(Other embodiments)
(A) In the above-described embodiment, the wiper driving device sets the wiper wiping speed and the wiping interval based on the amount of raindrops output by the raindrop detection device. However, the method of setting the wiper wiping speed and the wiping interval is not limited to this. When the wiper control device does not include a raindrop detection device, the wiper wiping interval may be set manually.

  As mentioned above, this invention is not limited to such embodiment, It can implement with a various form in the range which does not deviate from the summary.

4 ... Windshield,
5 ・ ・ ・ Wiper,
7 ... Battery (power supply source),
8 ... Wiper switch,
9 ... raindrop detection device,
10: Wiper driving device,
22 ... wiper motor,
221 ... Terminal (terminal for low-speed driving),
222 ... Terminal (terminal for high-speed driving),
24 ・ ・ ・ Cam switch,
241 ... Terminal (first terminal),
30 ... Wiper motor control circuit,
32... P-type MOSFET,
34 ... n-type MOSFET,
38... Microcomputer (control unit).

Claims (4)

A wiper driving device (10) for driving a wiper (5) for wiping raindrops on a windshield (4) of a vehicle,
A wiper motor (22) for reciprocatingly driving the wiper between a predetermined stop position and a maximum wiping position;
A wiper switch (8) capable of selecting a driving mode of the wiper including at least an intermittent mode capable of setting a time for the wiper to stop at the predetermined stop position;
A wiper motor control circuit that is electrically connected to the vehicle power supply source (7), the wiper motor, and the wiper switch, and that controls driving of the wiper motor based on a drive mode of the wiper selected by the wiper switch. 30),
When the wiper is at the predetermined stop position, the first terminal (241) is connected to the ground, or when the wiper is at a position other than the predetermined stop position, the first terminal is electrically connected to the power supply source. A cam switch (24) that can be switched to a connection;
With
The wiper motor control circuit
An n-type MOSFET having a source side terminal (NS1) connected to the first terminal and a drain side terminal (ND1) connected to driving terminals (221, 222) of the wiper motor that receives power supplied from the power supply source (32),
A p-type MOSFET (34) for electrically connecting a source side terminal (PS1) to the power supply source and connecting a drain side terminal (PD1) to the driving terminal;
The wiper switch, the n-type MOSFET, and the p-type MOSFET are electrically connected. When the intermittent mode is selected as the wiper drive mode by the wiper switch, the n-type MOSFET is turned on, and the wiper switch When the intermittent mode is selected as the driving mode of the wiper and the wiper starts moving from the predetermined stop position, the n-type MOSFET is turned off, the p-type MOSFET is turned on, and the wiper switch is used to A control unit (38) for turning on the n-type MOSFET after turning off the p-type MOSFET when the intermittent mode is selected as the drive mode of the wiper and the wiper is in a position other than the predetermined stop position;
A wiper drive device comprising: The drive terminal includes a high-speed drive terminal (222) for driving the wiper at a high speed when receiving power supplied from the power supply source,
The wiper switch is capable of selecting a high speed mode for driving the wiper at a high speed as the wiper driving mode,
2. The wiper driving device according to claim 1, wherein when the high-speed mode is selected as the driving mode of the wiper, the high-speed driving terminal and the power supply source are directly connected. The drive terminal includes a low-speed drive terminal (221) for driving the wiper at a low speed when receiving power supplied from the power supply source,
The wiper switch can select a low speed mode for driving the wiper at a low speed as a drive mode of the wiper,
3. The wiper drive device according to claim 1, wherein when the low-speed mode is selected as the drive mode of the wiper, the low-speed drive terminal and the power supply source are directly connected. A raindrop detection device (9) for detecting the amount of raindrops on the windshield and outputting a signal corresponding to the amount of raindrops on the windshield;
4. The wiper drive according to claim 1, wherein the control unit controls on / off of the n-type MOSFET and the p-type MOSFET based on a signal output from the raindrop detection device. 5. apparatus.

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