Rainfall detection system

Abstract

A calculation unit (120) is included in a wiper device (300) and receives, from the wiper device, a cam signal indicating a rotation position of a wiper motor (330) for driving a wiper blade (320). When the wiper device is caused to continuously sweep the wiper blade, the calculation unit (120): sets, as a mask period before turn-ON (M4), a period from a prescribed time before an ON timing (K2) at which the cam signal switches from OFF indicating a rotation end position of the wiper motor to ON indicating a rotation start position of the wiper motor to the ON timing; and performs wiper control by including the mask period before turn-ON into the mask period.

Description

Rainfall Detection System CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2024-19062 filed on February 12, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to rainfall detection systems.

[0003] A conventional wiper control device is proposed, for example, in Patent Document 1. The wiper control device acquires rainfall information from a rain sensor installed on the ceiling side of the windshield. When the wiper blade passes the rain sensor, raindrops are wiped off the windshield. Therefore, to avoid false detection of rainfall when the wiper blade passes the rain sensor, the wiper control device provides an invalid period within the wiper blade wiping cycle to invalidate the rainfall information.

[0004] Japanese Patent Application Laid-Open No. 2000-85538

[0005] Typically, a wiper control device acquires the wiping cycle of the wiper blades based on a cam signal output from a wiper motor for operating the wiper blades. For this purpose, the wiper motor includes a detector for detecting the rotational position of the wiper motor and outputting the cam signal. The detector includes, for example, a plurality of terminals.

[0006] The wiper control device starts driving the wiper motor in accordance with a control signal for operating the wiper blades. When the wiper motor starts rotating, the terminals of the detection unit are electrically connected to output an ON cam signal. When the wiper motor stops rotating after completing one reciprocating motion of the wiper blades, the terminals of the detection unit are electrically connected to output an OFF cam signal.

[0007] Normally, the wiper blades pass over the rain sensor while the cam signal is ON. Therefore, the wiper control device sets a mask period during which rainfall information is invalidated while the cam signal is ON. Specifically, the wiper control device starts measuring time based on the ON timing when the cam signal changes from OFF to ON. The mask period becomes valid after a certain time has elapsed since the start of measuring time.

[0008] The wiper blade drive mechanism is located on the ground side of the windshield, and the rain sensor is installed on the ceiling side of the windshield. That is, when the wiper blade is stopped, the position of the wiper blade is far from the position of the rain sensor.

[0009] In contrast, there are cases where the wiper blade drive mechanism is located on the ground side of the windshield and the rain sensor is installed on the ground side of the windshield, for example, when there is little space on the ceiling side of the windshield to install the rain sensor, or when the ground side of the windshield needs to be used effectively.

[0010] However, when the rain sensor is installed on the ground side of the windshield, the wiper blade's stopped position is closer to the rain sensor than when the rain sensor is installed on the ceiling side of the windshield. In other words, the time it takes for the wiper blade to pass the rain sensor after it starts moving is shorter than when the rain sensor is installed on the ceiling side of the windshield. This means that the wiper blade may pass the rain sensor after the wiper motor starts rotating but before the terminals of the detector are electrically connected to output an ON cam signal. As a result, the rain sensor may erroneously detect the amount of rain.

[0011] Note that the wiper blade drive mechanism is not limited to being located on the ground side of the windshield. For example, if the wiper blade drive mechanism is installed on the ceiling side and the rain sensor is installed on the ceiling side of the windshield, the rain sensor may also erroneously detect the amount of rain. In this way, if the rain sensor is installed on the windshield so that the wiper blade stop position and the rain sensor position are close to each other, the rain sensor may erroneously detect the amount of rain.

[0012] In consideration of the above points, the present disclosure aims to provide a rainfall detection system that can avoid false detection by the rain sensor when the rain sensor is installed on the windshield so that the stopping position of the wiper blade is close to the position of the rain sensor.

[0013] According to one aspect of the present disclosure, there is provided a rainfall detection system for controlling the wiper device in accordance with the amount of raindrops adhering to the windshield when the wiper device is configured as an automatic wiper that automatically operates wiper blades to wipe the windshield of a mobile vehicle, the system including: a rain sensor that is installed on the windshield at a position where the wiper blades pass and on the side of the windshield where the wiper blades are stopped, the rain sensor detecting raindrops adhering to the windshield and outputting a rainfall signal according to the amount of raindrops; and a calculation unit that receives the rainfall signal from the rain sensor and stores time-series data of rainfall information included in the rainfall signal, the calculation unit setting a masking period that invalidates part of the rainfall information stored in the control buffer, and causing the wiper device to perform continuous or intermittent wiping of the wiper blades as wiper control based on the rainfall information for which the masking period has been set. The calculation unit inputs a cam signal from the wiper device that indicates the rotational position of a wiper motor that is included in the wiper device and drives the wiper blades, and when the wiper device is causing the wiper blades to continuously wipe, sets the period from a predetermined time before the ON timing at which the cam signal switches from OFF, which indicates the end position of the wiper motor's rotation, to ON, which indicates the start position of the wiper motor's rotation, to the ON timing as a pre-ON mask period, and performs wiper control including the pre-ON mask period in the mask period.

[0014] According to this, during continuous wiping with the wiper blades, the pre-ON mask period is set before the cam signal turns ON. Therefore, even if the wiper blades pass over the rain sensor and wipe away raindrops before the cam signal turns ON, the rainfall information before the cam signal turns ON is not used for wiper control. Therefore, even if the rain sensor is installed on the windshield so that the wiper blade stop position and the rain sensor position are close to each other, erroneous detection by the rain sensor can be avoided.

[0015] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagram showing the configuration of a rainfall detection system and a wiper device according to a first embodiment, Fig. 2 is a diagram showing an example of a rain sensor mounting position relative to a windshield and a wiper blade stop position, Fig. 3 is an exploded perspective view showing a part of a wiper motor, Fig. 4 is a diagram showing a detection unit of the wiper motor, Fig. 5 is a flowchart showing the contents of a rainfall value selection process during intermittent wiping, Fig. 6 is a timing chart showing a cam signal during intermittent wiping, and Fig. 7 is a flowchart showing the contents of a rainfall value selection process during continuous wiping. 8 is a timing chart showing the cam signal during continuous wiping, FIG. 9 is a timing chart showing the wiper operation, cam signal, conventional mask, and mask period during continuous wiping during continuous wiping, FIG. 10 is a diagram showing the position of the wiper blade at time T13 in FIG. 9, FIG. 11 is a diagram showing the position of the wiper blade at time T15 in FIG. 9, FIG. 12 is a diagram showing the position of the wiper blade at time T17 in FIG. 9, and FIG. 13 is a timing chart showing the pre-ON mask period in the second embodiment.

[0016] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0017] First Embodiment A rainfall detection system according to the first embodiment performs wiper control to control the wiping speed of wiper blades of a wiper device in accordance with the amount of raindrops on the windshield of a vehicle such as an automobile or train, or a mobile object such as an aircraft or ship.

[0018] 1, the rainfall detection system 100 includes a rain sensor 110 and a calculation unit 120. The rain sensor 110 is a device that detects raindrops adhering to the windshield and outputs a rainfall signal corresponding to the amount of raindrops.

[0019] 2, the rain sensor 110 is installed on the vehicle windshield 200 at a position on the side of the stop position P1 of the wiper blade 320 where the wiper blade 320 passes. The stop position P1 of the wiper blade 320 is the position where the wiper blade 320 is stopped. In this embodiment, the stop position P1 of the wiper blade 320 is on the ground side of the windshield 200.

[0020] In this embodiment, the side of the wiper blade 320 at stop position P1 is the ground side of the windshield 200. Therefore, the rain sensor 110 is installed on the ground side of the windshield 200. The position on the windshield 200 through which the wiper blade 320 passes is within the wiping ranges 210, 220 of the windshield 200. For example, the rain sensor 110 is installed in the center of the windshield 200 in the width direction of the vehicle. Note that the left-right direction is the direction perpendicular to the top-bottom direction of the windshield 200, and corresponds to the left-right direction with respect to the traveling direction of the moving object.

[0021] Although not shown, the rain sensor 110 is an optical detection device that uses the refractive index of light to detect the amount of raindrops adhering to the windshield. The rain sensor 110 includes a light-emitting element, a light-receiving element, a lens, a circuit board, and a processing unit.

[0022] The light-emitting element is a light-emitting device that emits measurement light for detecting raindrops. The light-receiving element is a light-receiving device that receives the light from the light-emitting element. The lens is an optical component that guides the measurement light emitted from the light-emitting element to the interior, collimates it to become parallel light, guides the collimated measurement light to the outer surface of the windshield 200, and collects the light reflected from the outer surface and guides it to the light-receiving element.

[0023] The circuit board is a component on which electronic components (not shown), such as light-emitting elements, light-receiving elements, a processing unit, and a connector, are mounted. The processing unit drives the light-emitting elements and processes the detection results of the light-receiving elements. Each of the above components is housed in a case and packaged.

[0024] The rain sensor 110 defines the light intensity of the light receiving element as 100% when there are no raindrops on the windshield 200, and detects changes in this light intensity as the amount of rain. In other words, the rain sensor 110 detects a decrease in the light intensity as the amount of rain. The rain sensor 110 then outputs a rainfall signal indicating the amount of rain to the calculation unit 120. The rain sensor 110 sequentially outputs the rainfall signal, including data on the amount of rainfall over one control period, to the calculation unit 120.

[0025] The calculation unit 120 is configured as an ECU (Electrical Control Unit) that controls the wiper device 300 mounted on the vehicle. The calculation unit 120 is configured from a well-known microcomputer including a control buffer unit 121 such as a CPU, ROM, RAM, etc., and its peripheral circuits. The calculation unit 120 performs various calculations and processes according to a control program stored in the ROM.

[0026] The calculation unit 120 calculates the amount of rainfall adhering to the windshield 200 for each control cycle based on the rainfall signal from the rain sensor 110. That is, the calculation unit 120 calculates the total accumulated rainfall for one control cycle. The calculation unit 120 has a control buffer unit 121. The calculation unit 120 sequentially stores time-series data of rainfall information (total accumulated rainfall) calculated for each control cycle in the control buffer unit 121. Note that "storing" is synonymous with "memorizing."

[0027] The calculation unit 120 has a mask period that invalidates part of the rainfall information stored in the control buffer unit 121. When the calculation unit 120 receives an auto-wiper operation signal from the wiper device 300, the calculation unit 120 controls the wiper device 300 to perform continuous or intermittent wiping of the wiper blades 320 based on the rainfall information for which the mask period is set. The auto-wiper mode is a mode in which the wiper blades 320 are operated automatically.

[0028] The continuous wiping mode of the wiper blade 320 is a mode in which the wiper blade 320 starts its next operation immediately after returning to the stop position P1, thereby causing the wiper blade 320 to operate continuously. The intermittent wiping mode of the wiper blade 320 is a mode in which the wiper blade 320 starts its next operation a certain time after returning to the stop position P1, thereby causing the wiper blade 320 to operate intermittently. The calculation unit 120 determines whether the wiper blade 320 is to perform continuous wiping or intermittent wiping using data from which the rainfall amount during the masked period has been excluded, and outputs a control signal corresponding to the determination result to the wiper device 300.

[0029] The mask period is a period during which the time-series data of rainfall information corresponding to the mask period is prohibited from being used for wiper control. In this embodiment, in the continuous wiping mode of the auto wiper, the calculation unit 120 performs wiper control using the time-series data of rainfall information outside the mask period. On the other hand, in the intermittent wiping mode of the auto wiper, the calculation unit 120 sets the mask period, but performs wiper control using part of the time-series data of rainfall information for the mask period at timings other than the mask period.

[0030] The wiper device 300, together with the rainfall detection system 100, constitutes a wiper system for wiping the windshield 200. The wiper device 300 includes a wiper switch 310, wiper blades 320, a wiper motor 330, a rotation angle sensor 340, and a motor control unit 350. The wiper device 300 can be operated by a power source such as a battery installed in the vehicle.

[0031] The wiper switch 310 is operated by a user. The wiper switch 310 has operation positions such as "Hi," "Lo," and "AUTO." For example, "Hi" is a high-speed continuous wiping mode, and "Lo" is a low-speed continuous wiping mode.

[0032] The "AUTO" setting on the wiper switch 310 is an automatic wiper mode that determines the wiping speed of the wiper blades 320 depending on the amount of rain. In other words, "AUTO" is a mode in which the wiper blades 320 wipe continuously or intermittently depending on the amount of rain. In this embodiment, the wiper switch 310 is set to "AUTO." The wiper switch 310 outputs an operation signal indicating "AUTO" to the calculation unit 120.

[0033] The wiper blade 320 is a device that wipes away raindrops adhering to the windshield 200. The wiper blade 320 is also attached to a link mechanism (not shown). The link mechanism connects the wiper motor 330 and the wiper blade 320. The link mechanism converts the rotation of the wiper motor 330 into a wiping action of the wiper blade 320.

[0034] The link mechanism mainly includes a wiper arm that holds the wiper blade 320, a pivot lever that is connected to the wiper arm via a pivot shaft, and a link rod that connects the pivot lever and the wiper motor 330. In this embodiment, the link mechanism is disposed on the ground side of the windshield 200.

[0035] The wiper motor 330 generates rotational power for causing the wiper blade 320 to perform a wiping operation. As shown in Figures 3 and 4, the wiper motor 330 mainly includes a motor unit 331, a speed reduction mechanism 332, an output shaft 333, and a detection unit 334. The motor unit 331, the speed reduction mechanism 332, the output shaft 333, and the detection unit 334 are housed integrally in a housing (not shown).

[0036] The motor section 331 is configured as the rotating part of, for example, a brush motor. A worm gear 335 is formed by rolling on the outer circumferential surface of the shaft of the motor section 331. The worm gear 335 is engaged with a worm wheel 336.

[0037] The worm gear 335 and the worm wheel 336 constitute a speed reduction mechanism 332. The speed reduction mechanism 332 reduces the rotation speed of the motor unit 331 and outputs the reduced speed to the output shaft 333. When the wiper motor 330 is operating, it rotates (continuously) integrally with the output shaft 333 around its axis in one direction (the direction of arrow R in FIG. 3 ).

[0038] An output shaft 333 is coaxially fixed to the axial center of the worm wheel 336. The worm wheel 336 is rotatably supported by the housing via the output shaft 333. The output shaft 333 is supported by the housing and rotates at a reduced speed by the reduction mechanism 332. The tip side of the output shaft 333 protrudes outside the housing. The above-mentioned link mechanism is fixed to the tip of the output shaft 333.

[0039] In the wiper device 300, the link mechanism is rotated (continuously rotated) in one direction around the axis of the output shaft 333, integrally with the output shaft 333 of the wiper motor 330. As a result, the left and right wiper blades 320 rotate back and forth in the same direction on the windshield 200 in unison, and the left and right wiper blades 320 wipe the windshield 200 in a reciprocating manner. In this case, as shown in Figure 2, each wiper blade 320 rotates back and forth between a stop position P1, which is a lower reversal position, and an upper reversal position P2. The left and right wiper blades 320 are configured to be positioned at the stop position P1 during normal operation when the wiper motor 330 is not operating.

[0040] The detector 334 generates a cam signal that indicates the rotational position of the motor unit 331. As shown in Figures 3 and 4, the detector 334 is composed of a cam plate 334A that is directly attached to the worm wheel 336, and a pair of terminals, a P terminal 334B and a CL terminal 334C. The cam plate 334A is, for example, in the form of a generally fan-shaped plate piece that is formed concentrically around the axis of the output shaft 333. The cam plate 334A is attached by means of claw fitting or the like to part of the outer periphery of the surface of the worm wheel 336 that is opposite the output shaft 333 side.

[0041] The P terminal 334B and the CL terminal 334C are attached to the inner surface of the housing and are arranged to be electrically connected to the cam plate 334A when the wiper blade 320 is in the stop position P1.

[0042] In this embodiment, the rotation angle sensor 340 is configured to detect the electrical connection state between the P terminal 334B and the CL terminal 334C based on a voltage (cam signal) generated at the P terminal 334B. Note that a small current as an electrical signal flows between each of the terminals 334B, 334C and the cam plate 334A, for example, via a resistor. Therefore, the detection unit 334 generates a cam signal when the electrical connection state of each of the terminals 334B, 334C is switched by the rotation of the cam plate 334A.

[0043] Specifically, as shown in FIG. 4 , the P terminal 334B is electrically connected to the rotation angle sensor 340. The CL terminal 334C is connected to GND. As a result, when the cam plate 334A is in contact with the P terminal 334B and the CL terminal 334C, the voltage at the P terminal 334B becomes 0 V. The detector 334 detects that the wiper blade 320 is at the stop position P1 when the voltage generated at the P terminal 334B becomes 0 V. In other words, the detector 334 outputs an OFF cam signal indicating the end position of the wiper motor 330.

[0044] On the other hand, when the cam plate 334A is not in contact with the P terminal 334B or the CL terminal 334C, the voltage of the P terminal 334B is set to, for example, the power supply voltage Vcc. That is, the detection unit 334 outputs an ON cam signal that indicates the rotation start position of the wiper motor 330.

[0045] In this way, the detection unit 334 outputs the electrical connection state of the P terminal 334B and the CL terminal 334C as a cam signal, thereby being able to detect whether the wiper blade 320 is positioned at the stop position P1 and whether the wiper blade 320 is performing a wiping operation.

[0046] Note that "contact" is synonymous with "electrically connected." The configuration of the detection unit 334 shown in FIGS. 3 and 4 is an example. For example, the detection unit 334 may be configured with three terminals and cam plates having shapes corresponding to the terminals. The cam signal may be output directly to the calculation unit 120 without passing through the rotation angle sensor 340.

[0047] The rotation angle sensor 340 is a device that detects the rotation angle of the output shaft 333 of the wiper motor 330, which drives the link mechanism. For example, the rotation angle sensor 340 is provided in the reduction mechanism 332 of the wiper motor 330, and detects the rotation angle by converting the magnetic field (magnetic force) of an excitation coil or magnet that rotates in conjunction with the output shaft 333 into an electric current. For example, an MR (magnetoresistive) sensor that can detect an absolute angle is used as the rotation angle sensor 340. The rotation angle sensor 340 outputs a rotation signal that corresponds to the rotation angle of the output shaft 333 of the wiper motor 330 from a reference position of the output shaft 333.

[0048] The rotation signal is used by the calculation unit 120 to control the rotation speed of the wiper motor 330. That is, the calculation unit 120 calculates the position of the wiper blade 320 on the windshield 200 from the rotation angle of the output shaft 333 detected by the rotation angle sensor 340. The calculation unit 120 then controls the motor control unit 350 of the wiper device 300 so that the rotation speed of the output shaft 333 changes depending on the position of the wiper blade 320.

[0049] The motor control unit 350 controls the rotation of the wiper motor 330 based on the control signal input from the calculation unit 120. As a result, the motor control unit 350 performs the wiping operation of the wiper blades 320. The rainfall detection system 100 and the wiper device 300 are configured as described above.

[0050] Next, the rainfall value selection process used to determine the amount of rainfall will be described. First, the rainfall value selection process performed when the calculation unit 120 determines to cause the wiper blades 320 to intermittently wipe based on rainfall information when the automatic wiper is set will be described with reference to the flowchart in Figure 5. The flow in Figure 5 starts when intermittent wiping is enabled.

[0051] Here, during intermittent wiping, for example, the entire period during which the cam signal is ON is set in advance as a mask period.

[0052] In step S10, the calculation unit 120 determines whether the cam signal input from the rotation angle sensor 340 has switched from ON to OFF, that is, whether the wiper blade 320 is located at the stop position P1.

[0053] If the calculation unit 120 determines that the cam signal has not switched from ON to OFF, the flow ends and restarts the rainfall value selection process for intermittent wiping. For example, as shown in FIG. 6 , the time-series rainfall information data P and Q are stored sequentially in the control buffer unit 121 from two control cycles before OFF timing K1, at which the cam signal switches from ON to OFF. However, during intermittent wiping, a post-ON mask period M1 is set as a mask period for the period up to OFF timing K1, i.e., the entire period during which the cam signal is ON. Therefore, the calculation unit 120 sets the total volumetric rainfall values ​​P and Q to 0 and does not use the values ​​P and Q to determine whether the wiper blades 320 should be wiped continuously or intermittently.

[0054] During intermittent wiping of the wiper blade 320, for example, the period b control cycles after the OFF timing K1 is the range of erroneous detection by the rain sensor 110. "After b" refers to the timing b control cycles after the OFF timing K1. In this embodiment, "b" during intermittent wiping is set to b=3.

[0055] If the calculation unit 120 determines that the cam signal has switched from ON to OFF, the process proceeds to step S11 in FIG.

[0056] In step S11, measurement of the waiting time T1 starts from the OFF timing K1.

[0057] In step S12, time-series data of rainfall information for each control cycle is stored in the control buffer unit 121. For example, as shown in Fig. 6, data A, B, ... are stored in the control buffer unit 121 sequentially for each control cycle starting from OFF timing K1.

[0058] 5, the calculation unit 120 determines whether the waiting time T1 is equal to or greater than b+1. That is, the calculation unit 120 determines whether the waiting time T1 has exceeded b control cycles since the OFF timing K1.

[0059] In step S13, the calculation unit 120 sets the period from the OFF timing K1 until the elapse of a predetermined time as the post-OFF mask period M2. As described above, during intermittent wiping, the mask period is set to the entire ON period of the cam signal. In addition, the period from the OFF timing K1 to the post-OFF mask period M2 is also set as the mask period. This allows the period before and after the OFF timing K1, which falls within the false detection range of the rain sensor 110, to be set as the mask period.

[0060] If the waiting time T1 does not satisfy T1≧b+1, the process returns to step S12. On the other hand, if the waiting time T1 satisfies T1≧b+1, the process proceeds to step S14.

[0061] In step S14, the calculation unit 120 sequentially uses the rainfall values ​​stored in the control buffer unit 121 as the control rainfall value. Specifically, during the period from the elapse of the post-OFF mask period M2 to the ON timing K2 at which the cam signal switches from OFF to ON, the calculation unit 120 performs wiper control using the time-series data of rainfall information stored sequentially in the control buffer unit 121 from the OFF timing K1.

[0062] In the example shown in Figure 6, the calculation unit 120 uses the total volumetric rainfall values ​​A, B, and C stored in the control buffer unit 121 in order from the OFF timing K1 as the control rainfall value for rainfall determination from the timing when the post-OFF mask period M2 has elapsed.

[0063] In step S15, the calculation unit 120 determines whether the cam signal has switched from OFF to ON, that is, whether the OFF period of the cam signal has ended.

[0064] If the calculation unit 120 determines that the cam signal has not switched from OFF to ON, the calculation unit 120 returns to step S14 and continues to determine the amount of rainfall. On the other hand, if the calculation unit 120 determines that the cam signal has switched from OFF to ON, the calculation unit 120 proceeds to step S16.

[0065] In step S16, the calculation unit 120 sets the total accumulated rainfall value stored in the control buffer unit 121 after the ON timing K2 to 0. That is, the calculation unit 120 sets all the accumulated rainfall values ​​G, H, I, ... stored in the control buffer unit 121 after the ON timing K2 to 0, and does not use these values ​​in the rainfall amount determination that determines the control content of the auto-wiper.

[0066] Thus, the process for selecting a rainfall amount value for intermittent wiping ends. As long as the calculation unit 120 continues to determine that the wiper blade 320 is to be caused to perform intermittent wiping, the flow of FIG.

[0067] Next, the rainfall value selection process performed when the calculation unit 120 determines, based on rainfall information, that the wiper blades 320 should be continuously wiped while the automatic wiper function is enabled will be described with reference to the flowchart in Fig. 7. The flow in Fig. 7 starts when continuous wiping is enabled. Alternatively, if the amount of rain increases and the calculation unit 120 changes its determination from intermittent wiping to continuous wiping during the flow in Fig. 5, the process proceeds to the flow in Fig. 7 after the flow in Fig. 5 ends.

[0068] 8, during continuous wiping, for example, a period from ON timing K2 of the cam signal until a predetermined time later is set as a post-ON mask period M1. Also, a period from a predetermined period before OFF timing K1 of the cam signal until OFF timing K1 is set as a pre-OFF mask period M3. The post-ON mask period M1 and the pre-OFF mask period M3 are set as mask periods within the period when the cam signal is ON.

[0069] When the wiper blade 320 is continuously wiping, for example, the period a before and b after the ON timing K2 is the range of erroneous detection by the rain sensor 110. The period a before refers to the timing a control cycles before the ON timing K2. The calculation unit 120 sets the period from a predetermined time before the ON timing K2 of the cam signal to the ON timing K2 as the pre-ON mask period M4.

[0070] In this embodiment, for example, a and b are set to a=2 and b=3 during continuous wiping. That is, the post-ON mask period M1 is set to b control cycles. Also, during continuous wiping, the OFF period of the cam signal is set to a control cycles. Therefore, the calculation unit 120 sets the pre-ON mask period M4 to the entire period during which the cam signal is OFF.

[0071] Furthermore, during continuous wiping, the pre-ON mask period M4 and the post-ON mask period M1 are continuous across the ON timing K2 of the cam signal. In other words, the mask periods are continuous across the ON timing K2.

[0072] Then, in step S20 of FIG. 7 , similar to step S10, the calculation unit 120 determines whether the cam signal has switched from ON to OFF. If the calculation unit 120 determines that the cam signal has not switched from ON to OFF, the flow ends and the rainfall value selection process for continuous wiping is restarted. For example, as shown in FIG. 8 , before the cam signal turns OFF at timing K1, the time-series rainfall information data are P and Q, and these data are sequentially stored in the control buffer unit 121. However, the period up to the cam signal turning OFF at timing K1 is set as a pre-OFF mask period M3. Therefore, the calculation unit 120 sets the total volumetric rainfall values ​​of P and Q to 0 and does not use the values ​​of P and Q to determine whether the wiper blades 320 should be wiped continuously or intermittently in the automatic wiper.

[0073] On the other hand, if the calculation unit 120 determines that the cam signal has switched from ON to OFF, the process proceeds to step S21 in FIG.

[0074] In step S21, the calculation unit 120 sets the total accumulated rainfall value stored in the control buffer unit 121 after the OFF timing K1 to 0. That is, the calculation unit 120 sets the total accumulated rainfall values ​​A and B stored in the control buffer unit 121 after the OFF timing K1 to 0, and does not use these values ​​in the rainfall amount determination that determines the control content of the auto-wiper.

[0075] In step S22, the calculation unit 120 determines whether the cam signal has switched from OFF to ON. If the calculation unit 120 determines that the cam signal has not switched from OFF to ON, the calculation unit 120 returns to step S21. On the other hand, if the calculation unit 120 determines that the cam signal has switched from OFF to ON, the calculation unit 120 proceeds to step S23.

[0076] In step S23, measurement of the waiting time T2 starts from the ON timing K2.

[0077] In step S24, the calculation unit 120 determines whether the waiting time T2 satisfies T2≧b+1. That is, the calculation unit 120 determines whether the waiting time T2 has exceeded b control cycles since the ON timing K2. In other words, the calculation unit 120 determines whether the waiting time T2 has exceeded the post-ON mask period M1 since the ON timing K2. If the waiting time T2 does not satisfy T2≧b+1, the process proceeds to step S25.

[0078] In step S25, similarly to step S21, the calculation unit 120 sets the total accumulated rainfall value stored in the control buffer unit 121 after the OFF timing K1 to 0. That is, the calculation unit 120 sets all the accumulated rainfall values ​​C, D, and E stored in the control buffer unit 121 after the ON timing K2 to 0, and these values ​​are not used in the rainfall determination that determines the control content of the auto-wiper. After step S25 is completed, the process returns to step S23.

[0079] In step S24, if the waiting time T2 satisfies T2≧b+1, the process proceeds to step S26.

[0080] In step S26, the calculation unit 120 sets the control rainfall value to the rainfall value. That is, the calculation unit 120 sets the total integrated rainfall values ​​F, G, H, and I stored in the control buffer unit 121 after the post-ON mask period M1 has elapsed as the control rainfall value for rainfall determination.

[0081] In step S27, the calculation unit 120 determines whether the pre-OFF mask period M3 has begun. If the pre-OFF mask period M3 has not begun, the process returns to step S23. That is, the calculation unit 120 uses the total integrated rainfall values ​​F, G, H, and I stored in the control buffer unit 121 during the period from after the post-ON mask period M1 has elapsed until before the pre-OFF mask period M3 as control rainfall values ​​for rainfall determination. On the other hand, if the pre-OFF mask period M3 has begun, the process proceeds to step S28.

[0082] In step S28, similarly to steps S21 and S25, the calculation unit 120 sets the total accumulated rainfall value stored in the control buffer unit 121 during the pre-OFF mask period M3 to zero.

[0083] This completes the rainfall value selection process for intermittent wiping. As described above, during continuous wiping, wiper control is performed by including the pre-OFF mask period M3, the pre-ON mask period M4, and the post-ON mask period M1 in the mask period. The flow shown in FIG. 7 is repeated as long as the calculation unit 120 continues to determine that the wiper blades 320 should be continuously wiped. Alternatively, if the amount of rain decreases and the calculation unit 120 changes its determination from continuous wiping to intermittent wiping during the flow shown in FIG. 7, the calculation unit 120 transitions to the flow shown in FIG. 5 after the flow shown in FIG. 7 ends.

[0084] The entire mask period during continuous wiping is shown in Fig. 9. Fig. 9 is a timing chart showing wiper operation, a cam signal, a conventional mask set for the entire period when the cam signal is ON, and a mask period set in the flowchart of Fig. 7. The conventional mask is a conventional mask period set during the period when the cam signal is ON.

[0085] At time T10, the calculation unit 120 outputs a control signal to the motor control unit 350 to stop the operation of the wiper blade 320. The motor control unit 350 stops the wiper motor 330. As a result, at time T11 after time T10, the detection unit 334 outputs an OFF cam signal. Time T11 corresponds to the OFF timing K1.

[0086] Conventionally, it was possible to set a mask period during the ON period after the cam signal switched from OFF to ON, so the pre-OFF mask period M3 was valid until time T11 when the cam signal switched from ON to OFF.

[0087] In this embodiment, as described above, the pre-ON mask period M4 is set over the entire period in which the cam signal is OFF, so that the pre-ON mask period M4 is valid as a mask period from time T11 onwards.

[0088] After that, at time T12, the calculation unit 120 outputs a control signal to the motor control unit 350 to operate the wiper blade 320. The motor control unit 350 drives the wiper motor 330. As a result, the wiper motor 330 starts to move, and the detection unit 334 outputs an ON cam signal at time T13 after time T12. Also, as shown in FIG. 10 , the wiper blade 320 passes over the rain sensor 110.

[0089] The post-ON mask period M1 becomes effective from time T13. Time T13 corresponds to ON timing K2. The post-ON mask period M1 continues from the pre-ON mask period M4. The post-ON mask period M1 is a conventional mask because it is a mask during the period when the cam signal is ON. The post-ON mask period M1 ends at time T14.

[0090] The mask period is released at time T14. At time T15, for example, as shown in FIG. 11 , the wiper blade 320 has moved to the upper reversal position P2. Because the distance between the wiper blade 320 and the rain sensor 110 is large, the rain sensor 110 can properly detect the amount of rain. Therefore, during continuous wiping, the calculation unit 120 uses the total accumulated rainfall value detected by the rain sensor 110 as the control rainfall value for determining the amount of rainfall during the period from time T14, when the after-ON mask period M1 ends, to time T16, when the before-OFF mask period M3 becomes effective.

[0091] The pre-OFF mask period M3 becomes effective from time T16 onward. This is because the wiper blade 320 is approaching the rain sensor 110, and raindrops wiped by the wiper blade 320 pass over the rain sensor 110, making it difficult to properly detect the amount of rain.

[0092] 12, at time T17, for example, the wiper blade 320 has returned close to the rain sensor 110. After this, the process returns to time T10.

[0093] As described above, in this embodiment, the calculation unit 120 receives a cam signal from the wiper device 300 that indicates the rotational position of the wiper motor 330 for driving the wiper blades 320. When the wiper device 300 is causing the wiper blades 320 to continuously wipe, the calculation unit 120 sets a period from a predetermined time before the ON timing K2 of the cam signal to the ON timing K2 as a pre-ON mask period M4. The calculation unit 120 then performs wiper control by including the pre-ON mask period M4 in the mask period.

[0094] As a result, even if the wiper blade 320 passes over the rain sensor 110 and wipes away raindrops before the cam signal turns ON, the rainfall information before the cam signal turns ON is invalidated by the pre-ON mask period M4. In other words, the rainfall before and after the wiper blade 320 passes over the rain sensor 110 and wipes away raindrops is not used for wiper control. Therefore, even if the rain sensor 110 is installed on the ground side of the windshield 200 and is brought closer to the stop position P1 of the wiper blade 320, false detection by the rain sensor 110 can be avoided.

[0095] Second Embodiment In this embodiment, differences from the first embodiment will be mainly described. As shown in FIG. 13 , the calculation unit 120 does not set the pre-ON mask period M4 for the entire period in which the cam signal is OFF, but rather sets the pre-ON mask period M4 for part of the period in which the cam signal is OFF. That is, the calculation unit 120 sets the period from a predetermined time before ON timing K2 of the cam signal to ON timing K2 as the pre-ON mask period M4. In this way, it is sufficient to set the pre-ON mask period M4 at least immediately before the cam signal turns ON. This achieves the same effects as the first embodiment.

[0096] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0097] For example, as long as rain sensor 110 and stop position P1 of wiper blade 320 are close to each other, the position of rain sensor 110 on windshield 200 may be separated from the link mechanism that drives wiper blade 320. As an example, the link mechanism of wiper blade 320 may be located on the ground side of the windshield, stop position P1 of wiper blade 320 may be located at the right end of windshield 200 in the left-right direction, and rain sensor 110 may be located at the right end of windshield 200 in the left-right direction.

[0098] Furthermore, the stopping position P1 of the rain sensor 110 and the wiper blade 320 is not limited to being located on the ground side of the windshield 200, but may also be located on the ceiling side of the windshield 200 or on the right or left side in the left-right direction.

[0099] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0100] The technical features of the rain sensor disclosed in this specification are as follows: (Item 1) A rainfall detection system for controlling the wiper device (300) in accordance with the amount of raindrops adhering to the windshield (200) of a moving vehicle, when the wiper device (300) is configured as an automatic wiper that automatically operates wiper blades (320) that wipe the windshield (200), includes: a rain sensor (110) that is installed on the windshield at a position where the wiper blade passes on the side of the wiper blade stop position (P1), and that detects the raindrops adhering to the windshield and outputs a rainfall signal according to the amount of raindrops; and a calculation unit (120) that has an input of the rainfall signal from the rain sensor and stores time-series data of rainfall information included in the rainfall signal, and that sets a mask period that invalidates part of the rainfall information stored in the control buffer, and that controls the wiper device to perform continuous or intermittent wiping of the wiper blade based on the rainfall information for which the mask period has been set, wherein the calculation unit: a cam signal indicating a rotational position of a wiper motor (330) included in the wiper device and for driving the wiper blades is input from the wiper device, and when the wiper device is causing the wiper blades to continuously wipe, a pre-ON mask period (M4) is set as a period from a predetermined time before an ON timing (K2) at which the cam signal switches from OFF, indicating the end position of the wiper motor rotation, to ON, indicating the start position of the wiper motor rotation, until the ON timing, and the wiper control is performed while including the pre-ON mask period in the mask period. (Item 2) The rainfall detection system according to Item 1, wherein the calculation unit sets a period from the ON timing to a predetermined time later as a post-ON mask period (M1), sets the pre-ON mask period and the post-ON mask period so that the pre-ON mask period and the post-ON mask period are connected consecutively before and after the ON timing, and performs the wiper control by including the pre-ON mask period and the post-ON mask period in the mask period.(Item 3) The rainfall detection system according to item 1 or 2, wherein the calculation unit sets the pre-ON mask period to the entire period during which the cam signal is OFF. (Item 4) The rainfall detection system according to any one of items 1 to 3, wherein the calculation unit, when causing the wiper device to intermittently wipe the wiper blade, sets a period from OFF timing (K1) at which the cam signal switches from ON to OFF until a predetermined time has elapsed as a post-OFF mask period (M2), and performs the wiper control using the time-series data of the rainfall information sequentially stored in the control buffer unit from the OFF timing during the period during which the cam signal is OFF, during which the wiper control unit (Item 5) The rainfall detection system according to any one of Items 1 to 4, wherein the moving body is a vehicle, the stop position of the wiper blade of the wiper device is on the ground side of the windshield, and the rain sensor is installed on the ground side of the windshield.

Claims

1. A rainfall detection system for controlling the wiper device (300) in accordance with the amount of raindrops adhering to the windshield (200) of a moving vehicle, when the wiper device (300) is configured as an automatic wiper that automatically operates a wiper blade (320) that wipes the windshield (200), comprising: a rain sensor (110) installed on the windshield at a position where the wiper blade passes on the side of the wiper blade stop position (P1), to detect the raindrops adhering to the windshield and output a rainfall signal according to the amount of raindrops; and a calculation unit (120) having an input of the rainfall signal from the rain sensor and storing time-series data of rainfall information included in the rainfall signal, which sets a mask period that invalidates part of the rainfall information stored in the control buffer, and causes the wiper device to perform continuous or intermittent wiping of the wiper blade as the wiper control based on the rainfall information for which the mask period has been set, wherein the calculation unit: A rainfall detection system that inputs a cam signal from the wiper device that indicates the rotational position of a wiper motor (330) that is included in the wiper device and drives the wiper blade, and when the wiper device is causing the wiper blade to continuously wipe, sets a pre-ON mask period (M4) as a period from a predetermined time before ON timing (K2) at which the cam signal switches from OFF, indicating the end position of the wiper motor's rotation, to ON, indicating the start position of the wiper motor's rotation, until the ON timing, and performs the wiper control by including the pre-ON mask period in the mask period.

2. The rainfall detection system of claim 1, wherein the calculation unit sets the period from the ON timing until a predetermined time later as a post-ON mask period (M1), and sets the pre-ON mask period and the post-ON mask period so that the pre-ON mask period and the post-ON mask period are connected continuously before and after the ON timing, and performs the wiper control by including the pre-ON mask period and the post-ON mask period in the mask period.

3. The rainfall detection system according to claim 1 or 2, wherein the calculation unit sets the pre-ON mask period to the entire period during which the cam signal is OFF.

4. The rainfall detection system of claim 1 or 2, wherein the calculation unit, when causing the wiper device to intermittently wipe the wiper blade, sets the period from the OFF timing (K1) at which the cam signal switches from ON to OFF until a predetermined time has elapsed as a post-OFF mask period (M2), and during the period when the cam signal is OFF, from the elapse of the post-OFF mask period to the ON timing, performs wiper control using the time series data of the rainfall information stored sequentially in the control buffer unit from the OFF timing.

5. A rainfall detection system as described in claim 1 or 2, wherein the moving body is a vehicle, the stopping position of the wiper blade of the wiper device is on the ground side of the windshield, and the rain sensor is installed on the ground side of the windshield.

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