Wiper control device

Abstract

To provide a wiper control device that can estimate a rotation angle of a wiper and control overrun of the wiper, with a simple structure.SOLUTION: An estimating part 64 of a wiper control device 30 obtains values concerning currents Im_Hi and Im_Lo flowing in a wiper motor 100 that drives a wiper that reciprocates between a lower inversion position and an upper inversion position. The estimating part 64 estimates a wiper angle that is a rotation angle of the wiper, on the basis of current ripples having periodicity corresponding to driving of the wiper motor 100 of the currents flowing in the wiper motor 100. Further, a driving part 62 of the wiper control device 30 reduces electric power to be supplied to the wiper motor 100, when a position of the wiper is just before the lower inversion position or the position of the wiper is just before the upper inversion position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wiper control device. [Background technology]

[0002] As described in Patent Document 1, a wiper device is known that calculates the position of the wiper blade from a reference position based on the rotation speed of the wiper motor rotor detected by a Hall sensor and the reduction ratio of the wiper motor's reduction mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-43158 Summary of the Invention [Problem to be solved by the invention]

[0004] The wiper device described in Patent Document 1 is equipped with a Hall sensor that detects the rotation speed of the rotor. This requires wiring for signals from the Hall sensor, which complicates the configuration of the wiper device described in Patent Document 1. This increases the cost of the wiper device. In addition, overrun, which occurs when the wiper blade does not stop at the lower or upper reversal position but goes too far, can occur, and there is a need to suppress this overrun.

[0005] An object of the present disclosure is to provide a wiper control device that estimates the rotation angle of a wiper with a simple configuration and suppresses overrun of the wiper. [Means for solving the problem]

[0006] The invention of claim 1 is a wiper control device comprising: an acquisition unit (S200) that acquires a value related to a current (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) that has periodicity according to the drive of the wiper motor among the currents flowing through the wiper motor; and a drive unit (62) that reduces power supplied to the wiper motor when the wiper is positioned either immediately before the first position or immediately before the second position. The wiper motor has a first terminal (104) to which power is supplied for rotation at a first speed and a second terminal (106) to which power is supplied for rotation at a second speed slower than the first speed, and the drive unit reduces the power supplied to the first terminal and controls the power supplied to the second terminal when the wiper is in a position just before the first position or when the wiper is in a position just before the second position while power is supplied to the first terminal. This is a wiper control device. The invention of claim 3 provides a wiper control device including an acquisition unit (S200) that acquires values ​​related to current (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu), and an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) of the current flowing through the wiper motor, the current ripple having a periodicity corresponding to the drive of the wiper motor, the wiper motor having a first terminal (104) to which power is supplied for rotation at a first speed, and a second terminal (106) to which power is supplied for rotation at a second speed that is slower than the first speed, and the wiper control device includes a first element (35) that, when turned on, causes a current to flow through the wiper motor via the first terminal to rotate the wiper motor, and an estimation unit (S210) that, when turned on, causes a current to flow through the first terminal to rotate the wiper motor. The wiper control device further includes a second element (45) that rotates the wiper motor by passing a current through the terminal, and a drive unit (62) that controls the on / off of the first element and the second element. When the first element is on, the drive unit stops the supply of power to the first terminal by changing the first element from on to off when the wiper is in a position just before the first position or just before the second position, and supplies power to the second terminal by changing the second element from off to on. When the wiper is in a position just before the first position to the first position or just before the second position to the second position, the drive unit stops the supply of power to the second terminal by changing the first element from off to on, and stops the supply of power to the second terminal by changing the second element from on to off. Furthermore, the invention of claim 4 provides a wiper control device including: an acquisition unit (S200) that acquires a value related to a current (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); and an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) that has periodicity corresponding to the drive of the wiper motor, among the current flowing through the wiper motor. The wiper motor has a first terminal (104) to which power is supplied for rotation at a first speed, and a second terminal (106) to which power is supplied for rotation at a second speed that is slower than the first speed. When the wiper control device is turned on, a current is supplied to the wiper motor via the first terminal, thereby rotating the wiper motor. The wiper control device further includes a first element (35), a second element (45) that, when turned on, causes a current to flow through the wiper motor via the second terminal to rotate the wiper motor, and a drive unit (62) that controls the on / off of the first element and the second element. When the first element is on, the drive unit stops the supply of power to the first terminal by changing the first element from on to off when the wiper is in either the position immediately before the first position or the position immediately before the second position, and keeps the second element off. When the wiper is in either the position immediately before the first position to the first position or the position immediately before the second position to the second position, the drive unit stops the supply of power to the first terminal by changing the first element from off to on, and keeps the second element off.

[0007] This allows the wiper angle to be estimated without providing a Hall sensor that detects the rotor rotation speed. This eliminates the need for wiring for signals from the Hall sensor. Therefore, the wiper angle can be estimated with a simple configuration. In addition, the wiper moves smoothly to the first or second position by decelerating just before reaching the first or second position. This prevents the wiper from overrunning, which occurs when the wiper does not stop at the first or second position and instead moves too far.

[0008] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of a wiper drive system in which a wiper control device according to an embodiment is used; [Figure 2] FIG. 2 is a diagram showing a wiper of the wiper drive system. [Figure 3] 4 is a diagram showing the relationship between time and the current flowing through the wiper motor of the wiper drive system. [Figure 4] FIG. 4 is a diagram for explaining switching of a current detection range of the wiper control device. [Figure 5] 4 is a flowchart showing the processing of a drive unit of the wiper control device. [Figure 6] 5 is a flowchart showing the processing of an estimation unit of the wiper control device. [Figure 7] FIG. 10 is a diagram for explaining calculation of the number of pulses by an estimation unit. [Figure 8] FIG. 2 is a configuration diagram of a wiper drive system in which a wiper control device according to a first modified example of an embodiment is used. [Figure 9] 10 is a diagram for explaining calculation of the number of pulses by an estimation unit in the wiper control device according to the first modified example of the embodiment. FIG. [Figure 10] 10 is a diagram showing the relationship between the wiper angle and the on / off states of the Hi switch and the Lo switch, for explaining the processing of the drive unit in the wiper control device according to Modification 2 of the embodiment. FIG. [Figure 11] 10 is a diagram showing the relationship between the wiper angle and the on / off states of the Hi switch and the Lo switch, for explaining the processing of the drive unit in the wiper control device according to Modification 2 of the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals, and description thereof will be omitted.

[0011] The wiper control device of this embodiment estimates the rotation angle of the wiper with a simple configuration. For example, this wiper control device may be used in a wiper drive system of a vehicle. First, this wiper drive system will be described.

[0012] As shown in FIG. 1, the wiper drive system 1 includes a motor unit 10 , a motor ground 12 , a motor power supply 14 , a wiper switch 16 , and a wiper control device 30 .

[0013] The motor unit 10 has a wiper motor 100. The wiper motor 100 includes a Hi terminal 104, a Lo terminal 106, and a GND terminal 108. The Hi terminal 104 and the Lo terminal 106 are connected to a wiper control device 30, which will be described later. The GND terminal 108 is connected to a motor ground 12. The wiper motor 100 rotates at a relatively high speed when current is applied to the Hi terminal 104. The wiper motor 100 rotates at a slower speed when current is applied to the Lo terminal 106 than when current is applied to the Hi terminal 104. The rotation of the wiper motor 100 and a link mechanism (not shown) connected to the wiper motor 100 operate a wiper 90 of a vehicle, as shown in FIG. 2 .

[0014] Furthermore, as the wiper motor 100 rotates, the wiper 90 reciprocates between a lower reversal position Pd and an upper reversal position Pu on the windshield (not shown). During this operation, the wiper motor 100 repeatedly makes contact and disengages contact between the brushes and multiple commutator segments in the commutator of the wiper motor 100. As a result, as shown in FIG. 3, the wiper motor 100 has a characteristic in which a current ripple Ir is generated in the current flowing through the wiper motor 100, the current ripple Ir fluctuating periodically in response to the operation of the wiper motor 100. The amplitude of the current ripple Ir is, for example, 1 to 2 A. Furthermore, when a wiper switch 16 (described later) is turned off, the wiper motor 100 stops rotating so that the wiper 90 stops at the lower reversal position Pd.

[0015] Furthermore, as shown in FIG. 2 , the rotation angle of the wiper 90 when reciprocating between the lower reversal position Pd and the upper reversal position Pu is defined as the wiper angle θw. The angle between the lower reversal position Pd and the upper reversal position Pu is defined as the maximum angle θmax. The maximum angle θmax is, for example, 140 degrees. Here, the value of the wiper angle θw is defined as being greater than or equal to zero and less than or equal to 2×θmax. Furthermore, when the wiper angle θw is zero or 2×θmax, the wiper position Pw is defined as being at the lower reversal position Pd. When the wiper angle θw is θmax, the wiper position Pw is defined as being at the upper reversal position Pu. When 0<θw<θmax, the wiper 90 rotates from the lower reversal position Pd toward the upper reversal position Pu. When θmax<θw<2×θmax, the wiper 90 rotates from the upper reversal position Pu toward the lower reversal position Pd.

[0016] 1, the motor power supply 14 is a secondary battery such as a lithium ion battery, a nickel-metal hydride battery, a lead storage battery, etc. The voltage of the motor power supply 14 is, for example, 12V.

[0017] The wiper switch 16 is operated by the operator and outputs a signal to the control unit 60 of the wiper control device 30 described below to set the operating state of the wiper 90 to one of the continuous high-speed mode, continuous low-speed mode, intermittent mode, or stop mode, as described below.

[0018] The wiper control device 30 controls the wiper motor 100 by controlling the voltage applied to the wiper motor 100. In this way, the wiper control device 30 controls the driving of the wiper 90 connected to the wiper motor 100. Specifically, the wiper control device 30 has a Hi switch 35, a Hi wiring 37, a Hi current detection unit 39, a Hi switching unit 41, a Lo switch 45, a Lo wiring 47, a Lo current detection unit 49, a Lo switching unit 51, and a control unit 60.

[0019] The Hi switch 35 includes a relay, a transistor, or the like. One end of the Hi switch 35 is connected to the motor power supply 14. The other end of the Hi switch 35 is connected to the Hi terminal 104 via the Hi wiring 37. The Hi switch 35 corresponds to a drive element, and is turned on and off by a signal from the control unit 60, which will be described later. This causes current to flow to or be cut off from the Hi terminal 104.

[0020] Hi current detection unit 39 includes a shunt resistor, a current mirror circuit, a Hall IC, or the like. Hi current detection unit 39 detects Hi current Im_Hi. Furthermore, Hi current detection unit 39 outputs a signal corresponding to the detected Hi current Im_Hi to control unit 60 (described later) via Hi switching unit 41 (described later). Hi current Im_Hi is a current that flows from motor power supply 14 to Hi terminal 104 via Hi switch 35 and Hi wiring 37.

[0021] The Hi switching unit 41 switches the Hi current detection range. For example, the Hi switching unit 41 includes a switching element such as a transistor. The Hi switching unit 41 switches the electrical resistance of the Hi current detection unit 39 by turning the switching element on and off. This causes the Hi switching unit 41 to switch the Hi current detection range between the first Hi detection range and the second Hi detection range. The Hi current detection range is the detection range of the current detected by the Hi current detection unit 39. The first Hi detection range is, for example, 0 to 50 A as shown in FIG. 4. The second Hi detection range is a detection range that is smaller than the first Hi detection range, for example, 0 to 5 A. In FIG. 4, the first Hi detection range is indicated as Rd1. The second Hi detection range is indicated as Rd2. Because the second Hi detection range is smaller than the first Hi detection range, the resolution of the current detected in the second Hi detection range is higher than the resolution of the current detected in the first Hi detection range.

[0022] Also, here, the Hi switching unit 41 switches the Hi current detection range between the first Hi detection range and the second Hi detection range based on the Hi current Im_Hi. Specifically, when the Hi current Im_Hi is equal to or greater than the Hi protection threshold Im_Hi_th, the Hi switching unit 41 sets the Hi current detection range to the first Hi detection range. This allows the Hi current detection unit 39 to detect a relatively large Hi current Im_Hi. This makes it possible to detect abnormal heating of the Hi wiring 37, wiper motor 100, and wiper 90 due to a relatively large Hi current Im_Hi.

[0023] Furthermore, when the Hi current Im_Hi is less than the Hi protection threshold Im_Hi_th, the Hi switching unit 41 switches the Hi current detection range to the Hi second detection range. As a result, when the Hi current Im_Hi is less than the Hi protection threshold Im_Hi_th, the Hi current detection unit 39 can accurately detect the Hi current Im_Hi. This makes it easier to detect the current ripple Ir contained in the Hi current Im_Hi. The Hi protection threshold Im_Hi_th is set through experiments, simulations, etc. so as to protect the Hi wiring 37, the wiper motor 100, and the wiper 90 while also ensuring current detection accuracy.

[0024] Returning to FIG. 1, Lo switch 45 includes a relay, a transistor, or the like. One end of Lo switch 45 is connected to motor power supply 14. The other end of Lo switch 45 is connected to Lo terminal 106 via Lo wiring 47. Lo switch 45 corresponds to a drive element, and is turned on and off by a signal from control unit 60, which will be described later. This causes current to flow to or be cut off from Lo terminal 106.

[0025] The Lo current detection unit 49 includes a shunt resistor, a current mirror circuit, a Hall IC, or the like. The Lo current detection unit 49 detects the Lo current Im_Lo. The Lo current detection unit 49 outputs a signal corresponding to the detected Lo current Im_Lo to a control unit 60 (described later) via a Lo switching unit 51 (described later). The Lo current Im_Lo is a current that flows from the motor power supply 14 to the Lo terminal 106 via the Lo switch 45 and the Lo wiring 47.

[0026] The Lo switching unit 51 switches the Lo current detection range. For example, the Lo switching unit 51 includes a switching element such as a transistor. The Lo switching unit 51 switches the electrical resistance of the Lo current detection unit 49 by turning the switching element on and off. This causes the Lo switching unit 51 to switch the Lo current detection range between a first Lo detection range and a second Lo detection range. The Lo current detection range is the detection range of the current detected by the Lo current detection unit 49. The first Lo detection range is, for example, 0 to 50 A. The second Lo detection range is a detection range that is smaller than the first Lo detection range, for example, 0 to 5 A. Since the second Lo detection range is smaller than the first Lo detection range, the resolution of the current detected in the second Lo detection range is higher than the resolution of the current detected in the first Lo detection range.

[0027] Furthermore, here, the Lo switching unit 51 switches the Lo current detection range between the first Lo detection range and the second Lo detection range based on the Lo current Im_Lo. Specifically, when the Lo current Im_Lo is equal to or greater than the Lo protection threshold Im_Lo_th, the Lo switching unit 51 sets the Lo current detection range to the first Lo detection range. This allows the Lo current detection unit 49 to detect a relatively large Lo current Im_Lo. This makes it possible to detect abnormal heating of the Lo wiring 47, the wiper motor 100, and the wiper 90 due to a relatively large Lo current Im_Lo.

[0028] Furthermore, when the Lo current Im_Lo is less than the Lo protection threshold Im_Lo_th, the Lo switching unit 51 sets the Lo current detection range to the Lo second detection range. This allows the Lo current detection unit 49 to accurately detect the Lo current Im_Lo when the Lo current Im_Lo is less than the Lo protection threshold Im_Lo_th. This facilitates detection of the current ripple Ir contained in the Lo current Im_Lo. The Lo protection threshold Im_Lo_th is set through experiments, simulations, or the like so as to simultaneously protect the Lo wiring 47, the wiper motor 100, and the wiper 90 and ensure current detection accuracy.

[0029] The control unit 60 is mainly composed of a microcomputer and includes a CPU, ROM, flash memory, RAM, I / O, drive circuit, A / D converter, comparator circuit, DC-DC converter, low-pass filter, and bus lines connecting these components. The control unit 60 is driven by voltage from the motor power supply 14 or a power supply (not shown). The control unit 60 also includes a motor temperature estimation unit 61, a drive unit 62, and an estimation unit 64 as functional blocks.

[0030] The motor temperature estimation unit 61 estimates the temperature of the wiper motor 100 by executing a program stored in the control unit 60. For example, the motor temperature estimation unit 61 acquires the Hi current Im_Hi from the Hi current detection unit 39 via the Hi switching unit 41. The motor temperature estimation unit 61 also acquires the Lo current Im_Lo from the Lo current detection unit 49 via the Lo switching unit 51. The motor temperature estimation unit 61 also acquires the environmental temperature Te by communicating with a detection device (not shown). The motor temperature estimation unit 61 also acquires the motor voltage Vm via wiring (not shown). The detection device (not shown) detects the environmental temperature Te using, for example, a device such as a thermistor. The motor voltage Vm is the voltage of the wiper motor 100.

[0031] Furthermore, the motor temperature estimation unit 61 calculates the electric power of the wiper motor 100 from the acquired Hi current Im_Hi or Lo current Im_Lo and the motor voltage Vm. The motor temperature estimation unit 61 estimates the temperature of the wiper motor 100 using the calculated electric power, the acquired environmental temperature Te, and a map. The motor temperature estimation unit 61 outputs a signal corresponding to this estimated temperature of the wiper motor 100 to an estimation unit 64, which will be described later. When the environmental temperature Te is fixed, the amount of heat generated by the wiper motor 100 increases as the electric power increases. For this reason, the map for estimating the temperature of the wiper motor 100 is set, for example, so that the temperature of the wiper motor 100 increases as the electric power increases. When the electric power of the wiper motor 100 is fixed, the environmental temperature Te and the temperature of the wiper motor 100 are balanced. Therefore, the map for estimating the temperature of the wiper motor 100 is set so that the temperature of the wiper motor 100 increases as the environmental temperature Te increases.

[0032] The drive unit 62 executes a program stored in the control unit 60 to control the on / off of the Hi switch 35 and the Lo switch 45 based on signals from the wiper switch 16 and an estimation unit 64 (described later). As a result, the drive unit 62 controls the voltage applied to the wiper motor 100. As a result, the operating state of the wiper 90 is set to one of a continuous high-speed mode, a continuous low-speed mode, an intermittent mode, and a stopped state.

[0033] The estimation unit 64 executes a program stored in the control unit 60 to estimate the wiper angle θw based on the signal from the wiper switch 16, the temperature of the wiper motor 100, the Hi current Im_Hi, and the Lo current Im_Lo. The estimation unit 64 also outputs a signal corresponding to the estimated wiper angle θw to the drive unit 62.

[0034] The wiper drive system 1 is configured as described above. Next, the control of the voltage applied to the wiper motor 100 by the drive unit 62 through program execution by the control unit 60 will be described with reference to the flowchart of Fig. 5. The program of the control unit 60 is executed, for example, when the ignition or power supply of the vehicle (not shown) is turned on.

[0035] In step S100, the drive unit 62 acquires various information. Specifically, the drive unit 62 acquires a signal for switching the operation state of the wiper 90 between the continuous high-speed mode, the continuous low-speed mode, and the intermittent mode from the wiper switch 16. The drive unit 62 also acquires the wiper angle θw from the estimation unit 64.

[0036] Next, in step S102, the drive unit 62 determines whether the wiper switch 16 is on based on the signal from the wiper switch 16 acquired in step S100. Then, when the drive unit 62 acquires a signal in step S100 to change the operating state of the wiper 90 to the continuous high-speed mode, the continuous low-speed mode, or the intermittent mode, the drive unit 62 determines that the wiper switch 16 is on. Thereafter, the process of the drive unit 62 proceeds to step S104. On the other hand, when the drive unit 62 acquires a signal in step S100 to stop the operating state of the wiper 90, the drive unit 62 determines that the wiper switch 16 is off. At this time, the wiper 90 has stopped and there is no longer any need to drive the wiper 90, so the process of the drive unit 62 returns to step S100.

[0037] In step S104 following step S102, the drive unit 62 determines whether the wiper angle θw acquired in step S100 is equal to or greater than θmax-Δ and less than θmax. As a result, the drive unit 62 determines whether the wiper position Pw is immediately before the upper reversal position Pu. The drive unit 62 also determines whether the wiper angle θw acquired in step S100 is equal to or greater than 2×θmax-Δ and less than 2×θmax. As a result, the drive unit 62 determines whether the wiper position Pw is immediately before the lower reversal position Pd. Note that Δ is set by experiment, simulation, or the like so that it can be determined whether the wiper position Pw is immediately before the lower reversal position Pd or the upper reversal position Pu. For example, Δ is 1 to 10 degrees.

[0038] When the wiper angle θw is less than θmax-Δ or is equal to θmax, the wiper position Pw is not immediately before the upper reversal position Pu, and the process by the drive unit 62 proceeds to step S106. When the wiper angle θw is greater than θmax and less than 2×θmax-Δ or is equal to 2×θmax, the wiper position Pw is not immediately before the lower reversal position Pd, and the process by the drive unit 62 proceeds to step S106. When the wiper angle θw is equal to or greater than θmax-Δ but less than θmax, the wiper position Pw is immediately before the upper reversal position Pu, and the process by the drive unit 62 proceeds to step S108. When the wiper angle θw is equal to or greater than 2×θmax-Δ but less than 2×θmax, the wiper position Pw is immediately before the lower reversal position Pd, and the process by the drive unit 62 proceeds to step S108.

[0039] In step S106 following step S104, the drive unit 62 turns on the Hi switch 35 or the Lo switch 45. This causes the wiper motor 100 to rotate, thereby driving the wiper 90.

[0040] Here, for example, assume that the wiper switch 16 is operated by an operator to output a signal to the drive unit 62 to change the operation state of the wiper 90 to the continuous high-speed mode. At this time, the drive unit 62 turns on the Hi switch 35. As a result, a voltage is applied to the wiper motor 100 from the motor power supply 14 via the Hi switch 35, the Hi wiring 37, the Hi current detection unit 39, and the Hi terminal 104. As a result, the wiper motor 100 rotates at a higher speed than when current is applied to the Lo terminal 106. Therefore, the wiper 90 connected to the wiper motor 100 rotates at a higher speed, and the operation state of the wiper 90 changes to the continuous high-speed mode. At this time, the Lo switch 45 is turned off.

[0041] Also, for example, suppose that the operator operates the wiper switch 16 to output a signal to the drive unit 62 to change the operation state of the wiper 90 to the continuous low speed mode. At this time, the drive unit 62 turns on the Lo switch 45. As a result, a voltage is applied to the wiper motor 100 from the motor power supply 14 via the Lo switch 45, the Lo wiring 47, the Lo current detection unit 49, and the Lo terminal 106. As a result, the wiper motor 100 rotates at a slower speed than when current is applied to the Hi terminal 104. Therefore, the wiper 90 connected to the wiper motor 100 rotates at a slower speed, and the operation state of the wiper 90 changes to the continuous low speed mode. Note that at this time, the Hi switch 35 is turned off. Furthermore, when the operation state of the wiper 90 is in the intermittent mode, the drive unit 62 turns on the Lo switch 45. As a result, the wiper motor 100 rotates at a slower speed. Furthermore, when the wiper 90 reciprocates between the lower reversal position Pd and the upper reversal position Pu and the wiper position Pw is at the lower reversal position Pd, the drive unit 62 turns off the Lo switch 45. This causes the wiper motor 100 to temporarily stop, and the wiper 90 also temporarily stops. Thereafter, the drive unit 62 turns on the Lo switch 45. This causes the wiper motor 100 to rotate at a low speed. Therefore, these operations cause the wiper 90 to intermittently reciprocate between the lower reversal position Pd and the upper reversal position Pu.

[0042] After the driving unit 62 controls the Hi switch 35 and the Lo switch 45 in this manner, the processing of the driving unit 62 returns to step S100.

[0043] In step S108 following step S104, the wiper position Pw is immediately before the lower reversal position Pd or the upper reversal position Pu. Therefore, in step S108, the drive unit 62 performs PWM control on the wiper motor 100 by controlling the on / off of the Hi switch 35 or the Lo switch 45. As a result, the drive unit 62 reduces the power supplied to the wiper motor 100. This causes the wiper 90 to decelerate, thereby smoothly moving to the lower reversal position Pd or the upper reversal position Pu. Therefore, for example, the operating noise of the wiper 90 generated when the wiper position Pw is the lower reversal position Pd or the upper reversal position Pu is reduced. Note that PWM stands for Pulse Width Modulation.

[0044] Specifically, when the wiper 90 is in the continuous high-speed mode, the drive unit 62 repeatedly turns on the Hi switch 35 for a first Hi time and then turns it off for a second Hi time. When the wiper 90 is in the continuous low-speed mode, the drive unit 62 repeatedly turns on the Lo switch 45 for a first Lo time and then turns it off for a second Lo time. These operations reduce the power supplied to the wiper motor 100, thereby decelerating the wiper 90. This allows the wiper 90 to move smoothly. When the wiper 90 is stopped, the wiper 90 smoothly stops at the lower reversal position Pd. The Hi first time, Hi second time, Lo first time, and Lo second time are set by experiment, simulation, or the like, so that the power supplied to the wiper motor 100 is reduced and the wiper 90 moves smoothly. In addition, by gradually changing the Hi first time, Hi second time, Lo first time, and Lo second time, the power supplied to the wiper motor 100 is changed, thereby making the operation of the wiper 90 smoother.

[0045] After the driving unit 62 has thus performed on / off control of either the Hi switch 35 or the Lo switch 45, the processing of the driving unit 62 returns to step S100.

[0046] As described above, the drive unit 62 controls the voltage applied to the wiper motor 100. Next, the estimation of the wiper angle θw by the estimating unit 64 through program execution by the control unit 60 will be described with reference to the flowchart in Fig. 6. Note that the period of a series of operations from when the estimating unit 64 starts processing in step S200 until when the processing returns to step S200 is defined as the control cycle τ of the estimating unit 64.

[0047] In step S200, the estimation unit 64 acquires various information. Specifically, the estimation unit 64 acquires a signal from the wiper switch 16 to switch the operation state of the wiper 90 between continuous high-speed mode, continuous low-speed mode, intermittent mode, and stop. The estimation unit 64 also acquires the temperature of the wiper motor 100 from the motor temperature estimation unit 61. The estimation unit 64 also acquires the high current Im_Hi from the high current detection unit 39. The estimation unit 64 also acquires the low current Im_Lo from the low current detection unit 49. The estimation unit 64 also acquires the torque of the wiper motor 100 from a torque estimation device (not shown). The torque estimation device estimates the torque of the wiper motor 100 based on, for example, the state of the windshield (not shown), the vehicle speed, and the power of the wiper motor 100.

[0048] For example, assume that the wiper 90 is in the continuous high-speed mode. At this time, the Hi switch 35 is turned on. As a result, a voltage is applied to the wiper motor 100 from the motor power supply 14 via the Hi switch 35, the Hi wiring 37, the Hi current detector 39, and the Hi terminal 104. As a result, a current flows through the wiper motor 100, causing the wiper motor 100 to rotate, and the Hi current Im_Hi includes a current ripple Ir. As a result, the Hi current Im_Hi fluctuates periodically.

[0049] Also, for example, assume that the operation state of the wiper 90 is the continuous low-speed mode or the intermittent mode. At this time, the Lo switch 45 is turned on. Therefore, a voltage is applied to the wiper motor 100 from the motor power supply 14 via the Lo switch 45, the Lo wiring 47, the Lo current detection unit 49, and the Lo terminal 106. As a result, a current flows through the wiper motor 100, causing the wiper motor 100 to rotate, and the Lo current Im_Lo includes a current ripple Ir. Therefore, the Lo current Im_Lo fluctuates periodically.

[0050] Furthermore, as described above, a current ripple Ir is generated due to contact and non-contact between the commutator and the brush of the wiper motor 100. The number of times that the change amount ΔIm becomes equal to or greater than the change threshold value ΔIm_th while the wiper 90 moves from the lower reversal position Pd to the upper reversal position Pu and while the wiper 90 moves from the upper reversal position Pu to the lower reversal position Pd is uniquely determined by the structure of the wiper motor 100. Therefore, the number of times that the change amount ΔIm becomes equal to or greater than the change threshold value ΔIm_th is counted as the number of pulses N, thereby enabling estimation of the wiper angle θw.

[0051] Furthermore, as the voltage applied to the wiper motor 100 changes, the current flowing through the wiper motor 100 changes, and so the current ripple Ir and the amount of change ΔIm change. Also, as the temperature of the wiper motor 100 changes, the current ripple Ir and the amount of change ΔIm change. Furthermore, as the torque of the wiper motor 100 changes, the current ripple Ir and the amount of change ΔIm change. Therefore, it is preferable to change the change threshold ΔIm_th depending on the voltage applied to the wiper motor 100, the temperature of the wiper motor 100, and the torque of the wiper motor 100.

[0052] Therefore, as shown in the flowchart of Fig. 6, in step S202 following step S200, the estimation unit 64 calculates the amount of change ΔIm as shown in Fig. 7. The estimation unit 64 also calculates a change threshold ΔIm_th.

[0053] For example, assume that the wiper 90 is in the continuous high-speed mode. In this case, the estimation unit 64 calculates the difference between the Hi current Im_Hi(n) in the current control cycle τ(n) and the Hi current Im_Hi(n-1) in the previous control cycle τ(n-1). The estimation unit 64 then calculates the amount of change ΔIm. The amount of change ΔIm may be the absolute value of the difference.

[0054] Also, for example, assume that the wiper 90 is in the continuous low speed mode or the intermittent mode. In this case, the estimation unit 64 calculates the difference between the Lo current Im_Lo(n) in the current control cycle τ(n) and the Lo current Im_Lo(n-1) in the previous control cycle τ(n-1). From this, the estimation unit 64 calculates the change amount ΔIm.

[0055] Furthermore, the estimation unit 64 calculates the change threshold value ΔIm_th based on the temperature of the wiper motor 100, the voltage applied to the wiper motor 100, and the torque of the wiper motor 100 acquired in step S200. Specifically, the estimation unit 64 calculates the change threshold value ΔIm_th by using the temperature of the wiper motor 100, the voltage applied to the wiper motor 100, the torque of the wiper motor 100, and a map. The map for calculating the change threshold value ΔIm_th is set, for example, so that the change threshold value ΔIm_th increases as the temperature of the wiper motor 100 decreases. The map for calculating the change threshold value ΔIm_th is set, for example, so that the change threshold value ΔIm_th increases as the voltage applied to the wiper motor 100 increases. The map for calculating the change threshold value ΔIm_th is set, for example, so that the change threshold value ΔIm_th increases as the torque of the wiper motor 100 increases.

[0056] 6, next, in step S204, the estimation unit 64 determines whether the change ΔIm calculated in step S202 is equal to or greater than the change threshold ΔIm_th. If the change ΔIm is equal to or greater than the change threshold ΔIm_th, the processing by the estimation unit 64 proceeds to step S206. If the change ΔIm is less than the change threshold ΔIm_th, the processing by the estimation unit 64 proceeds to step S208.

[0057] In step S206 following step S204, the change amount ΔIm is equal to or greater than the change threshold value ΔIm_th, so at this time, the estimation unit 64 calculates the number of pulses N(n) in the current control cycle τ(n) by adding 1 to the number of pulses N(n-1) in the previous control cycle τ(n-1).

[0058] In step S208 following step S204, the change amount ΔIm is less than the change threshold ΔIm_th, so at this time, the estimation unit 64 sets the number of pulses N(n) in the current control cycle τ(n) to the number of pulses N(n-1) in the previous control cycle τ(n-1).

[0059] As described above, the rotation angle of the wiper motor 100 can be estimated from the number of times when the change amount ΔIm is equal to or greater than the change threshold value ΔIm_th, that is, the number of pulses N, and therefore the wiper angle θw can be estimated.

[0060] Therefore, in step S210, the estimation unit 64 estimates the wiper angle θw based on the calculated number of pulses N(n) in the current control cycle τ(n) and the map. The estimation unit 64 outputs a signal corresponding to the estimated wiper angle θw to the drive unit 62. The process of the estimation unit 64 then returns to step S200. The map for estimating the wiper angle θw from the number of pulses N is set based on the characteristics of the link mechanism (not shown) and the wiper motor 100, as well as experiments and simulations. For example, assume that the number of pulses N when the wiper 90 reciprocates between the lower reversal position Pd and the upper reversal position Pu is 1,000. In this case, when the number of pulses N(n) in the current control cycle τ(n) is 500, the wiper angle θw is estimated to be the maximum angle θmax, and the wiper position Pw is estimated to be the upper reversal position Pu. In this case, for example, when the number of pulses N(n) in the current control cycle τ(n) is 1000, the wiper angle θw is estimated to be 2×θmax, and the wiper position Pw is estimated to be the lower reversal position Pd. At this time, the number of pulses N may be reset.

[0061] As described above, the estimating unit 64 estimates the wiper angle θw. Next, it will be explained how the wiper control device 30 estimates the wiper angle θw with a simple configuration.

[0062] In step S200, the estimation unit 64 functions as an acquisition unit that acquires a value related to the current flowing through the wiper motor 100. In step S210, the estimation unit 64 estimates the wiper angle θw based on a current ripple Ir, which is part of the current flowing through the wiper motor 100 and has a periodicity corresponding to the operation of the wiper motor 100. The wiper motor 100 drives the wiper 90. The wiper 90 reciprocates between a lower reversal position Pd and an upper reversal position Pu. The lower reversal position Pd corresponds to the first position. The upper reversal position Pu corresponds to the second position. The wiper angle θw is the rotation angle of the wiper 90.

[0063] As a result, the wiper angle θw is estimated without providing a Hall sensor that detects the rotor rotation speed. This eliminates the need to provide wiring for signals from the Hall sensor. Therefore, the wiper angle θw is estimated with a simple configuration. In addition, the wiper position Pw may be estimated using a cam switch that turns on and off depending on the rotation of the wiper motor 100. In contrast, the wiper control device 30 of this embodiment estimates the wiper position Pw using the above configuration, so it does not need to be provided with a cam switch.

[0064] As described in Japanese Patent Application Laid-Open No. 10-105246, the current rotational position and rotational speed of a motor can be determined based on a current ripple pulse in the motor current and the polarity of the motor current, which reverses depending on the direction of rotation of the motor. In contrast, the wiper control device 30 of this embodiment estimates the wiper angle θw based on the current ripple Ir. Therefore, the wiper control device 30 differs from the invention described in Japanese Patent Application Laid-Open No. 10-105246. Furthermore, the wiper control device 30 of this embodiment achieves an advantageous effect different from the invention described in Japanese Patent Application Laid-Open No. 10-105246, namely, the ability to estimate the wiper angle θw. Therefore, the wiper control device 30 is novel and inventive.

[0065] Furthermore, the wiper control device 30 of this embodiment also provides the following effects.

[0066] [1] The estimation unit 64 estimates the wiper angle θw based on the pulse count N. This makes it easier to estimate the wiper angle θw. The pulse count N corresponds to the number of times when the absolute value of the change amount ΔIm of the current flowing through the wiper motor 100 is equal to or greater than the change threshold ΔIm_th.

[0067] [2] As described above, the current flowing through the wiper motor 100 changes as the voltage applied to the wiper motor 100 changes, and therefore the current ripple Ir and the amount of change ΔIm change. Furthermore, the current ripple Ir and the amount of change ΔIm change as the temperature of the wiper motor 100 changes. Furthermore, the current ripple Ir and the amount of change ΔIm change as the torque of the wiper motor 100 changes.

[0068] In response to this, in step S202, the estimation unit 64 changes the change threshold value ΔIm_th in accordance with a change in the voltage of the wiper motor 100. Also, in step S202, the estimation unit 64 changes the change threshold value ΔIm_th in accordance with a change in the temperature of the wiper motor 100. Furthermore, in step S202, the estimation unit 64 changes the change threshold value ΔIm_th in accordance with a change in the torque of the wiper motor 100.

[0069] As a result, the accuracy of calculating the number of pulses N, which is calculated by comparing the amount of change ΔIm with the change threshold ΔIm_th, is improved, and the accuracy of estimating the wiper angle θw is improved.

[0070] [3] The wiper control device 30 further includes a Hi current detection unit 39 and a Hi switching unit 41. The Hi current detection unit 39 detects the Hi current Im_Hi. The Hi switching unit 41 switches the detection range of the current detected by the Hi current detection unit 39. When the Hi current Im_Hi is equal to or greater than the Hi protection threshold Im_Hi_th, the Hi switching unit 41 makes the Hi current detection range larger than the detection range when the Hi current Im_Hi is less than the Hi protection threshold Im_Hi_th. When the Hi current Im_Hi is less than the Hi protection threshold Im_Hi_th, the Hi switching unit 41 makes the Hi current detection range smaller than the detection range when the Hi current Im_Hi is equal to or greater than the Hi protection threshold Im_Hi_th.

[0071] As a result, when the Hi current Im_Hi is equal to or greater than the Hi protection threshold Im_Hi_th, the Hi current detection unit 39 can detect a relatively large Hi current Im_Hi. This makes it possible to detect abnormal heat generation in the Hi wiring 37, wiper motor 100, and wiper 90 due to a relatively large Hi current Im_Hi. Furthermore, when the Hi current Im_Hi is less than the Hi protection threshold Im_Hi_th, the resolution is relatively high, so the Hi current detection unit 39 can accurately detect the Hi current Im_Hi. This improves the detection accuracy of the current ripple Ir, thereby improving the calculation accuracy of the pulse number N. This, in turn, improves the estimation accuracy of the wiper angle θw.

[0072] The wiper control device 30 also includes a Lo current detection unit 49 and a Lo switching unit 51. The Lo current detection unit 49 detects the Lo current Im_Lo. The Lo switching unit 51 switches the detection range of the current detected by the Lo current detection unit 49. When the Lo current Im_Lo is equal to or greater than the Lo protection threshold Im_Lo_th, the Lo switching unit 51 makes the Lo current detection range larger than the detection range when the Lo current Im_Lo is less than the Lo protection threshold Im_Lo_th. When the Lo current Im_Lo is less than the Lo protection threshold Im_Lo_th, the Lo switching unit 51 makes the Lo current detection range smaller than the detection range when the Lo current Im_Lo is equal to or greater than the Lo protection threshold Im_Lo_th.

[0073] As a result, when the Lo current Im_Lo is equal to or greater than the Lo protection threshold Im_Lo_th, the Lo current detection unit 49 can detect a relatively large Lo current Im_Lo. This makes it possible to detect abnormal heat generation in the Lo wiring 47, wiper motor 100, and wiper 90 due to a relatively large Lo current Im_Lo. Furthermore, when the Lo current Im_Lo is less than the Lo protection threshold Im_Lo_th, the resolution is relatively high, so the Lo current detection unit 49 can accurately detect the Lo current Im_Lo. This improves the detection accuracy of the current ripple Ir, thereby improving the calculation accuracy of the pulse number N. This improves the estimation accuracy of the wiper angle θw.

[0074] [4] The drive unit 62 reduces the power supplied to the wiper motor 100 when the wiper position Pw is immediately before the lower reversal position Pd or when the wiper position Pw is immediately before the upper reversal position Pu.

[0075] As a result, the wiper 90 is decelerated immediately before the lower reversal position Pd or the upper reversal position Pu, and thus moves smoothly to the lower reversal position Pd or the upper reversal position Pu. This prevents the wiper 90 from overrunning, which occurs when the wiper 90 does not stop at the lower reversal position Pd or the upper reversal position Pu. In addition, the operating noise of the wiper 90 generated when the wiper position Pw is the lower reversal position Pd or the upper reversal position Pu is reduced.

[0076] (Variation 1) In the above embodiment, in step S108, the drive unit 62 performs on / off control of the Hi switch 35 or the Lo switch 45. As a result, the drive unit 62 reduces the power supplied to the wiper motor 100. Meanwhile, the means for reducing the power supplied to the wiper motor 100 by the drive unit 62 is not limited to the above on / off control. For example, the drive unit 62 may reduce the power supplied to the wiper motor 100 by controlling a DC-DC converter (not shown) connected to the motor power supply 14 to lower the voltage applied to the wiper motor 100 from the motor power supply 14.

[0077] In the above embodiment, the estimation unit 64 may output a signal corresponding to the wiper angle θw estimated in step S210 to an external device. For example, the external device is a washer unit 70, as shown in FIG. 8. The washer unit 70 controls the timing of spraying washer fluid to wash the windshield (not shown) based on the signal from the estimation unit 64. For example, the washer unit 70 sprays washer fluid when the wiper angle θw estimated by the estimation unit 64 is zero or 2×θmax, i.e., when the wiper position Pw is at the lower reversal position Pd.

[0078] In the above embodiment, the estimation unit 64 calculates the number of times when the change amount ΔIm is equal to or greater than the change threshold ΔIm_th as the pulse number N. However, the pulse number N is not limited to the number of times when the change amount ΔIm is equal to or greater than the change threshold ΔIm_th. For example, as shown in FIG. 9 , the estimation unit 64 may calculate the number of times when the current flowing through the wiper motor 100 changes from less than the current threshold Im_th to equal to or greater than the current threshold Im_th as the pulse number N. Alternatively, the estimation unit 64 may calculate the number of times when the current flowing through the wiper motor 100 changes from greater than the current threshold Im_th to equal to or less than the current threshold Im_th as the pulse number N. Note that the current threshold Im_th is calculated based on, for example, the temperature of the wiper motor 100, the voltage applied to the wiper motor 100, and the torque of the wiper motor 100, similar to the change threshold ΔIm_th.

[0079] Furthermore, in the above embodiment, the Hi switching unit 41 switches the Hi current detection range between the first Hi detection range and the second Hi detection range based on the Hi current Im_Hi. Alternatively, the Hi switching unit 41 may switch the Hi current detection range between the first Hi detection range and the second Hi detection range without relying on the Hi current Im_Hi. For example, the Hi switching unit 41 may alternately switch the Hi current detection range between the first Hi detection range and the second Hi detection range over time. Similarly, the Lo switching unit 51 may switch the Lo current detection range between the first Lo detection range and the second Lo detection range without relying on the Lo current Im_Lo. For example, the Lo switching unit 51 may alternately switch the Lo current detection range between the first Lo detection range and the second Lo detection range over time.

[0080] In the above embodiment, the Hi switch 35, Hi current detection unit 39, Lo switch 45, and Lo current detection unit 49 are each separate. However, the Hi switch 35 and Hi current detection unit 39 may be integrated. Furthermore, the Lo switch 45 and Lo current detection unit 49 may be integrated. Furthermore, the Hi switch 35, Hi current detection unit 39, Lo switch 45, and Lo current detection unit 49 may be integrated.

[0081] (Variation 2) In the above embodiment, in step S108, the drive unit 62 performs PWM control on the wiper motor 100 by controlling the on / off of the Hi switch 35 or the Lo switch 45. This prevents the wiper 90 from overrunning without stopping at the lower reversal position Pd or the upper reversal position Pu.

[0082] In contrast, the wiper motor 100 of the second modification is a permanent magnet field type DC commutator motor, and may be a multi-speed motor, such as that disclosed in Japanese Patent Laid-Open Publication No. 10-503640, in which a current supply circuit for the armature is changed by selectively switching between a low-speed brush and a high-speed brush, thereby switching the motor's rotation speed between low and high speeds. Specifically, at least a pair of permanent magnets is fixed to the inner surface of a motor yoke (not shown), a winding is attached to the core of the armature, for example, by lap winding, and a Hi terminal 104, a Lo terminal 106, and a GND terminal 108, which serve as brushes, are arranged on the commutator so as to be in sliding contact with the commutator. Because the Hi terminal 104 is arranged at a position more advanced than the Lo terminal 106, when the Hi terminal 104 is selected and power is supplied, the motor rotation speed can be faster than when the Lo terminal 106 is selected. As described above, the wiper motor 100 of Modification 2 can be driven to rotate at a low speed or a high speed by selectively switching between the Hi terminal 104 and the Lo terminal 106 and supplying power without PWM control. When the wiper motor 100 of Modification 2 is used, assume that the Hi switch 35 is on and the wiper position Pw is immediately before the upper reversal position Pu, and the wiper angle θw is θmax-Δ. At this time, the drive unit 62 changes the Hi switch 35 from on to off, as shown in FIG. 10 . This causes the drive unit 62 to stop supplying power to the Hi terminal 104. At this time, the drive unit 62 also changes the Lo switch 45 from off to on. This causes the drive unit 62 to supply power to the Lo terminal 106. The rotation speed of the motor when the Hi terminal 104 is selected is higher than the rotation speed of the motor when the Lo terminal 106 is selected, and corresponds to a first speed. Furthermore, the rotation speed of the motor when the Lo terminal 106 is selected is lower than the rotation speed of the motor when the Hi terminal 104 is selected, and corresponds to the second speed.

[0083] Furthermore, when the wiper position Pw changes from just before the upper reversal position Pu to the upper reversal position Pu, in this case, when the wiper angle θw changes from θmax-Δ to θmax, the drive unit 62 changes the Hi switch 35 from off to on. This causes the drive unit 62 to supply power to the Hi terminal 104. At this time, the drive unit 62 also changes the Lo switch 45 from on to off. This causes the drive unit 62 to stop supplying power to the Lo terminal 106.

[0084] Furthermore, when the Hi switch 35 is on and the wiper position Pw is immediately before the lower reversal position Pd, for example, the wiper angle θw is 2×θmax−Δ. At this time, the drive unit 62 changes the Hi switch 35 from on to off. As a result, the drive unit 62 stops the power supply to the Hi terminal 104. At this time, the drive unit 62 also changes the Lo switch 45 from off to on. As a result, the drive unit 62 supplies power to the Lo terminal 106.

[0085] Furthermore, when the wiper position Pw changes from just before the lower reversal position Pd to the lower reversal position Pd, in this case, when the wiper angle θw changes from 2×θmax−Δ to 2×θmax, the drive unit 62 changes the Hi switch 35 from off to on. This causes the drive unit 62 to supply power to the Hi terminal 104. At this time, the drive unit 62 also changes the Lo switch 45 from on to off. This causes the drive unit 62 to stop supplying power to the Lo terminal 106.

[0086] Even with this process by the drive unit 62, the wiper 90 is decelerated immediately before the lower reversal position Pd or the upper reversal position Pu, allowing the wiper 90 to move smoothly to the lower reversal position Pd or the upper reversal position Pu. This prevents the wiper 90 from overrunning. In addition, the operating noise of the wiper 90 generated when the wiper position Pw is the lower reversal position Pd or the upper reversal position Pu is reduced.

[0087] In the process of the drive unit 62, the drive unit 62 turns the Lo switch 45 on and off. On the other hand, as shown in Fig. 11, when the wiper angle θw is equal to or greater than θmax-Δ and equal to or less than θmax, the drive unit 62 may keep the Lo switch 45 off without turning it on. Furthermore, when the wiper angle θw is equal to or greater than 2 × θmax-Δ and equal to or less than 2 × θmax, the drive unit 62 may keep the Lo switch 45 off without turning it on.

[0088] By the process of the drive unit 62, the wiper 90 is decelerated immediately before the lower reversing position Pd or the upper reversing position Pu, so that the wiper 90 smoothly moves to the lower reversing position Pd or the upper reversing position Pu. As a result, overrun and operating noise of the wiper 90 are suppressed.

[0089] In the second modification, the Hi terminal 104 corresponds to a first terminal to which power is supplied, and the Lo terminal 106 corresponds to a second terminal to which power smaller than that supplied to the first terminal is supplied. The Hi switch 35 corresponds to a first element that, when turned on, causes a current to flow to the wiper motor via the first terminal, thereby rotating the wiper motor. The Lo switch 45 corresponds to a second element that, when turned on, causes a current to flow to the wiper motor via the second terminal, thereby rotating the wiper motor.

[0090] Also, as described in Japanese Patent Application Laid-Open No. 2007-237921, there is known a wiper device that controls a drive means so that the angular velocity and angular acceleration of the wiper rotation shaft at the reversal position of the wiper arm become zero.

[0091] This wiper device requires a sensor for detecting the angular velocity and angular acceleration of the wiper rotation shaft, which increases the number of parts in the wiper device and therefore the cost of the wiper device.

[0092] In contrast, in the above-described embodiment, modified example 1, and modified example 2, the overrun and operating noise of the wiper 90 are suppressed without using a sensor that detects the angular velocity and angular acceleration of the wiper 90. Therefore, in the above-described embodiment, modified example 1, and modified example 2, an increase in the number of parts of the wiper control device 30 is suppressed, and therefore an increase in the cost of the wiper control device 30 is suppressed while the overrun and operating noise of the wiper 90 are suppressed.

[0093] (Other embodiments) The present disclosure is not limited to the above-described embodiments, and appropriate modifications can be made to the above-described embodiments. Furthermore, it goes without saying that the elements constituting the embodiments in the above-described embodiments are not necessarily essential unless they are specifically stated as essential or are considered to be clearly essential in principle.

[0094] The acquisition unit, estimation unit, driver, and method described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the acquisition unit, estimation unit, driver, and method described herein may be implemented by a special-purpose computer configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the acquisition unit, estimation unit, driver, and method described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0095] The above-described embodiment and each of the above-described modified examples may be combined as appropriate.

[0096] (Aspects of the present disclosure) As is clear from the above description of the embodiments and modifications, the disclosure of this specification includes at least the following aspects.

[0097] [Point 1] an acquisition unit (S200) that acquires values ​​related to currents (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) having a periodicity corresponding to the drive of the wiper motor among currents flowing through the wiper motor; A wiper control device comprising: [Point 2] The wiper control device according to aspect 1, wherein the estimation unit estimates the wiper angle based on the number (N) of times when the absolute value of the change (ΔIm) of the current flowing to the wiper motor is equal to or greater than a threshold (ΔIm_th). [Point 3] The wiper control device according to Aspect 1, wherein the estimation unit estimates the wiper angle based on the number (N) of times when the current flowing through the wiper motor changes from less than a threshold (Im_th) to equal to or greater than the threshold. [Point 4] The wiper control device according to Aspect 1, wherein the estimation unit estimates the wiper angle based on the number (N) of times that the current flowing through the wiper motor changes from being greater than a threshold (Im_th) to being equal to or less than the threshold. [Point 5] 5. The wiper control device according to any one of Aspects 2 to 4, wherein the estimation unit changes the threshold value in accordance with a change in voltage of the wiper motor. [Point 6] The wiper control device according to any one of Aspects 2 to 5, wherein the estimation unit changes the threshold value in accordance with a change in the temperature of the wiper motor. [Point 7] 7. The wiper control device according to any one of Aspects 2 to 6, wherein the estimation unit changes the threshold value in accordance with a change in torque of the wiper motor. [Point 8] The wiper control device includes: a current detection unit (39, 49) for detecting a current flowing through the wiper motor; a switching unit (41, 51) for switching a detection range of the current detected by the current detection unit; Furthermore, The switching unit is When the current flowing through the wiper motor is equal to or greater than a protection threshold (Im_Hi_th, Im_Lo_th), the detection range is set to be larger than the detection range when the current flowing through the wiper motor is less than the protection threshold (Im_Hi_th, Im_Lo_th), A wiper control device according to any one of Aspects 1 to 7, wherein when the current flowing through the wiper motor is less than the protection threshold, the detection range is made smaller than the detection range when the current flowing through the wiper motor is equal to or greater than the protection threshold. [Point 9] The wiper control device includes: a current detection unit (39, 49) for detecting a current flowing through the wiper motor; a switching unit (41, 51) for switching a detection range of the current detected by the current detection unit; Furthermore, A wiper control device described in any one of Aspects 1 to 7, wherein the switching unit switches the detection range between a first detection range and a second detection range that is smaller than the first detection range over time.

[0098] The disclosure of this specification also includes at least the following aspects.

[0099] [Point 10] The wiper control device according to any one of Aspects 1 to 9, further comprising a drive unit (62) that reduces the power supplied to the wiper motor when the wiper is in a position just before the first position or when the wiper is in a position just before the second position. [Point 11] The wiper control device further includes a drive element (35, 45) that, when turned on, causes a current to flow through the wiper motor, thereby rotating the wiper motor; The wiper control device described in aspect 10, wherein the drive unit reduces the power supplied to the wiper motor by turning the drive element on and off when the wiper is in a position just before the first position or when the wiper is in a position just before the second position. [Point 12] The wiper motor is a first terminal (104) to which power is supplied to rotate at a first speed; a second terminal (106) to which power is supplied to rotate the rotor at a second speed slower than the first speed; and The wiper control device includes: a first element (35) that, when turned on, causes a current to flow through the wiper motor via the first terminal, thereby rotating the wiper motor; a second element (45) that, when turned on, causes a current to flow through the wiper motor via the second terminal, thereby rotating the wiper motor; a driving unit (62) that controls on / off of the first element and the second element; Furthermore, The drive unit is When the first element is on, and the wiper is positioned immediately before the first position or immediately before the second position, the first element is turned off to stop power supply to the first terminal, and the second element is turned on to supply power to the second terminal, A wiper control device according to any one of aspects 1 to 9, wherein when the position of the wiper changes from just before the first position to the first position, or when the position of the wiper changes from just before the second position to the second position, the first element is turned from off to on to supply power to the first terminal, and the second element is turned from on to off to stop the supply of power to the second terminal. [Point 13] The wiper motor is a first terminal (104) to which power is supplied to rotate at a first speed; a second terminal (106) to which power is supplied to rotate the rotor at a second speed slower than the first speed; and The wiper control device includes: a first element (35) that, when turned on, causes a current to flow through the wiper motor via the first terminal, thereby rotating the wiper motor; a second element (45) that, when turned on, causes a current to flow through the wiper motor via the second terminal, thereby rotating the wiper motor; a driving unit (62) that controls on / off of the first element and the second element; Furthermore, The drive unit is When the first element is on, and the wiper is positioned just before the first position or just before the second position, the first element is turned off to stop the power supply to the first terminal and keep the second element off; A wiper control device according to any one of aspects 1 to 9, wherein when the position of the wiper changes from just before the first position to the first position, or when the position of the wiper changes from just before the second position to the second position, the first element is turned on from off to supply power to the first terminal, and the second element is kept off. [Explanation of symbols]

[0100] 14 Motor power supply 16 Wiper switch 35 Hi switch 39 Hi current detection section 41 Hi switch 45 Lo switch 49 Lo current detection section 51 Lo switch section 62 Drive unit 64 Estimation part

Claims

1. A wiper control device, an acquisition unit (S200) that acquires values ​​related to currents (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) having a periodicity corresponding to the drive of the wiper motor among currents flowing through the wiper motor; a drive unit (62) that reduces power supplied to the wiper motor when the wiper is in a position immediately before the first position or when the wiper is in a position immediately before the second position; Equipped with The wiper motor is a first terminal (104) to which power is supplied to rotate at a first speed; a second terminal (106) to which power is supplied to rotate the rotor at a second speed slower than the first speed; and The drive unit is When power is supplied to the first terminal, the wiper is in a position immediately before the first position, or the wiper is in a position immediately before the second position; A wiper control device that reduces the power supplied to the first terminal and controls the power supplied to the second terminal.

2. The wiper control device further includes a drive element (35, 45) that, when turned on, causes a current to flow through the wiper motor, thereby rotating the wiper motor; 2. The wiper control device according to claim 1, wherein the drive unit reduces the power supplied to the first terminal by switching the drive element from on to off when the wiper is in a position just before the first position or when the wiper is in a position just before the second position.

3. A wiper control device, an acquisition unit (S200) that acquires values ​​related to currents (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) having a periodicity corresponding to the drive of the wiper motor among currents flowing through the wiper motor; Equipped with The wiper motor is a first terminal (104) to which power is supplied to rotate at a first speed; a second terminal (106) to which power is supplied to rotate the rotor at a second speed slower than the first speed; and The wiper control device includes: a first element (35) that, when turned on, causes a current to flow through the wiper motor via the first terminal, thereby rotating the wiper motor; a second element (45) that, when turned on, causes a current to flow through the wiper motor via the second terminal, thereby rotating the wiper motor; a driving unit (62) that controls the on / off of the first element and the second element; Furthermore, The drive unit is When the first element is on, and the wiper is positioned immediately before the first position or immediately before the second position, the first element is turned off to stop the supply of power to the first terminal, and the second element is turned on to supply power to the second terminal, When the wiper position changes from just before the first position to the first position, or when the wiper position changes from just before the second position to the second position, the wiper control device supplies power to the first terminal by switching the first element from off to on, and stops the power supply to the second terminal by switching the second element from on to off.

4. A wiper control device, an acquisition unit (S200) that acquires values ​​related to currents (Im_Hi, Im_Lo) flowing through a wiper motor (100) that drives a wiper (90) that reciprocates between a first position (Pd) and a second position (Pu); an estimation unit (S210) that estimates a wiper angle (θw) that is a rotation angle of the wiper based on a current ripple (Ir) having a periodicity corresponding to the drive of the wiper motor among currents flowing through the wiper motor; Equipped with The wiper motor is a first terminal (104) to which power is supplied to rotate at a first speed; a second terminal (106) to which power is supplied to rotate the rotor at a second speed slower than the first speed; and The wiper control device includes: a first element (35) that, when turned on, causes a current to flow through the wiper motor via the first terminal, thereby rotating the wiper motor; a second element (45) that, when turned on, causes a current to flow through the wiper motor via the second terminal, thereby rotating the wiper motor; a driving unit (62) that controls the on / off of the first element and the second element; Furthermore, The drive unit is When the first element is on, and the wiper is positioned just before the first position or just before the second position, the first element is turned off to stop the power supply to the first terminal and the second element is kept off; When the wiper position changes from just before the first position to the first position, or when the wiper position changes from just before the second position to the second position, the wiper control device supplies power to the first terminal by switching the first element from off to on, and keeps the second element off.

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