JP2983346B2 - Wiper control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiper control device which is suitably implemented for a vehicle and drives a wiper blade at a wiping interval suitable for a rainy condition.

[0002]

2. Description of the Related Art A so-called automatic wiper control device for controlling a wiper operation based on the output of a raindrop sensor, in a typical conventional technology, integrates the output of a raindrop sensor and, when the integrated value becomes equal to or larger than a predetermined threshold value, The wiper blade is configured to start the wiping operation.

That is, a piezoelectric or optical raindrop sensor derives an output having a peak value and a pulse width corresponding to the diameter of the raindrop that has arrived. The output from the raindrop sensor is level-discriminated at a predetermined level by a waveform shaping circuit, shaped into a rectangular wave pulse, realized by a microcomputer or the like, and read into a processing circuit for controlling a wiper operation. The processing circuit accumulates the pulse widths of the read raindrop pulses, and starts the wiping operation when the accumulated value becomes equal to or greater than a predetermined threshold value.

[0004]

In the above-mentioned prior art,
In a normal rainfall state, the wiping operation can be performed at a wiping interval that matches the driver's feeling, but there is a disadvantage that the wiping operation is delayed in a very light rain. That is, when extremely small diameter raindrops due to drizzle or jumping of the preceding vehicle arrive, the integrated value does not easily become more than the threshold value, and thus, even though the forward visibility is deteriorated, No wiping operation is performed. This gives the driver discomfort. In addition, when driving becomes difficult, the driver must cancel the auto mode and manually switch to the LO operation or the HI operation to perform the wiping operation, which makes the operation complicated. Would.

[0005] It is an object of the present invention to provide a wiper control device capable of improving the responsiveness at the time of extremely light rain.

[0006]

According to the present invention, there is provided a raindrop sensor for detecting a rainfall state, and a drive means for reciprocatingly driving a wiper blade for removing raindrops adhering on the surface to be wiped on the surface to be wiped. The output pulse from the raindrop sensor,
The pulse width and the number of pulses are respectively integrated, and a predetermined threshold is provided for each integrated value, and either one of the integrated values reaches the corresponding threshold first, and
Control means for outputting a drive signal indicating that the wiper blade should be driven to the drive means, at the earlier of the predetermined intermittent time after the end of the previous wiping operation of the wiper blade; And a wiper control device.

Further, according to the present invention, the control means may include a time until one of the integrated values reaches the corresponding threshold value first, and the integrated value at the time when the intermittent time has elapsed. The intermittent time is updated based on at least one of the output pulse frequency and the output pulse frequency.

[0008]

According to the present invention, an output pulse corresponding to a rainfall state is derived from a piezoelectric or optical raindrop sensor.
A control device implemented by a microcomputer or the like reads the output pulse and integrates the pulse width and the pulse number. A threshold value is set in advance for each of the integrated values obtained in this manner, and the control unit determines whether the wiper blade has completed the previous wiping operation at the time when any of the integrated values is equal to or greater than the corresponding threshold value. A drive signal is output to a drive unit realized by a motor or the like at the earlier of the time when the predetermined intermittent time has elapsed and the time when the predetermined intermittent time has elapsed. The drive means drives the wiper blade to reciprocate on a surface to be wiped such as a windshield in response to a drive signal.

Therefore, in a normal rainfall state, the integrated value of the pulse width becomes equal to or larger than the threshold value earlier than the integrated value of the number of pulses. On the other hand, for a raindrop having a very small diameter such as drizzle or a jumped-up raindrop, Even if the integrated value of the pulse width only slightly increases, the wiping operation is performed by the increase of the integrated value of the pulse number. In this way, the responsiveness at the time of extremely small rain can be improved.

The intermittent time is within an intermittent time set after the previous wiping operation, and when each of the integrated values is equal to or greater than a corresponding threshold, corresponds to the time until the integrated value is equal to or greater than the threshold. For example, when the value becomes equal to or more than the threshold value within 80% of the intermittent time, the next intermittent time is updated to be short. When each integrated value is less than the threshold value at the time when the intermittent time has elapsed, the intermittent time is set longer based on the integrated value at that time, for example, when the integrated value is less than 閾 値 of the threshold value. Be updated. For example, 0.5 sec based on the pulse frequency of the output pulse
When three or more pulses arrive within the interval, the intermittent time may be updated to be short.

[0011]

FIG. 1 is a block diagram showing an electrical configuration of a wiper control device 1 according to one embodiment of the present invention. This wiper control device 1 is used for a vehicle, and when an automatic wiper switch 2 is turned on, a control circuit 3 drives and controls a wiper motor 5 as a driving unit in response to an output from a raindrop sensor 4. This is a so-called automatic wiper control device that performs a wiping operation by reciprocally displacing a wiper blade that does not operate on a windshield.

The raindrop sensor 4 includes, for example, a pair of light emitting elements 4a and a light receiving element 4b. The raindrop sensor 4 detects a change in light receiving level caused by raindrops passing through an optical path 4c formed by the light receiving and emitting elements 4b and 4a. An optical raindrop sensor that detects the amount of rainfall based on the rainfall.

That is, the light emitting element 4a realized by a light emitting diode or the like is driven by a driving circuit 4d to blink at a high frequency of, for example, 100 KHz as shown in FIG. Therefore, an optical path 4c between the light emitting element 4a and the light receiving element 4b realized by a photodiode or the like.
When the raindrop passes through the light-receiving element 4b,
In (2), as indicated by reference signs p1 and p2, the amplitude is modulated and derived.

The output from the light receiving element 4b is supplied to a tuning circuit 4e.
The oscillation frequency of the driving circuit 4d is 100 kHz.
After the front and rear bands are filtered, they are input to the detection circuit 4f. The detection circuit 4f performs envelope detection of the input signal as shown in FIG. 2C, and supplies a peak value output corresponding to the diameter of the raindrop to the pulse expansion circuit 4g.

The pulse expansion circuit 4g converts the input signal into the signal shown in FIG.
As shown in (4), the output is extended to a pulse length corresponding to the peak value. The output from the pulse decompression circuit 4g is input to the control circuit 3 and shaped by a waveform shaping circuit 11 into a rectangular wave pulse as shown in FIG. Circuit 1
2 is input. The output of the automatic wiper switch 2 is input to the processing circuit 12 after noise components such as so-called chattering are removed by a waveform shaping circuit 13.

Each circuit in the control circuit 3 including the processing circuit 12 is connected to the constant voltage circuit 29 from the power supply line L2.
, Power is supplied from the battery 23. When power is supplied from the constant voltage circuit 29 and the auto wiper switch 2 is turned on, the processing circuit 12 outputs the pulse width and pulse of the output pulse from the raindrop sensor 4 shown in FIG. Integrate each number,
The integrated values M1 and M2 are predetermined threshold values RP,
The wiper motor 5 is driven at the earlier of the time when the RN is equal to or more than RN and the time when a predetermined intermittent time WOT has elapsed after the end of the previous wiping operation of the wiper blade.

The intermittent time WOT can be selected, for example, into seven steps as shown in Table 1. Therefore, when the first step is selected, the wiper motor 5 is set to a high-speed continuous operation state, when the second step is selected, the low-speed continuous operation state is set, and when the third step is selected, 1.5 seconds. , And then, in the fourth step, 3 seconds, in the fifth step, 6 seconds,
The intermittent operation state is set to 12 seconds in the sixth step and 24 seconds in the longest seventh step.

[0018]

[Table 1]

In each of the above steps, the integrated values M1, M2
Are equal to or greater than the thresholds RP and RN, respectively, from the end of the previous wiping operation of the wiper blade, the integrated value M
Time WCT until M1, M2 exceed thresholds RP, RN
Is set based on Further, even if the intermittent time WOT elapses, if both integrated values M1 and M2 are less than the threshold values RP and RN, the steps are set based on the integrated values M1 and M2 at the time when the intermittent time WOT has elapsed. You.

That is, for example, the intermittent time WOT of 80
%, And if the integrated values M1 and M2 are equal to or greater than the thresholds RP and RN, respectively, within the time WUP that is the
The step of T is set shorter by one step, and the intermittent time is changed to be shorter. On the other hand, if the integrated value M1 is less than the value MDN which is の of the threshold value RP at the time when the intermittent time WOT has elapsed, the step of the intermittent time WOT is changed by one step. Such a step change threshold is shown in FIG. Intermittent time W as described above
By performing the update operation of the OT and the integrating operation of the output of the raindrop sensor 4, the automatic wiper control is realized.

When the wiper motor 5 is driven at a low speed, the processing circuit 12 outputs a drive signal from the output terminal P2 to the line L3. This drive signal is applied to the base of the transistor Tr2 via the resistor R3 and the bias resistor R4. The emitter of the transistor Tr2 is grounded, and the collector is connected to the power supply line L2 via the relay coil 27 of the relay 26.

On the other hand, the relay switch 2 of the relay 26
8 has two individual contacts 28a and 28b, one of which is connected to the power line L2 and the other of which is connected to the common contact 30c of the cam switch 30 via the line L4. I have. The common contact 24c of the relay switch 24 of the relay 21 is connected to the common contact 28c of the relay switch 28,
a is connected to the low-speed power input terminal 5a of the wiper motor 5.

When the wiper motor 5 is continuously driven at a high speed, the processing circuit 12 outputs a drive signal from the output terminals P1 and P2 to the lines L1 and L3. The drive signal for the line L1 is input to the base of the transistor Tr1 via the resistors R1 and R2, and the drive signal for the line L3 is input to the base of the transistor Tr2 via the resistors R3 and R4.

The transistor Tr1 has an emitter grounded and a collector connected to the relay coil 22 of the relay 21.
To the power supply line L2. One individual contact 24b of the relay switch 24 of the relay 21 is
It is connected to a high-speed power input terminal 5b of the wiper motor 5.

In connection with the wiper motor 5, a cam switch 30 is provided, and the cam switch 30 is connected to the individual contact 3 when the wiper blade is at the initial position.
0a, the wiper motor 5 is started, the wiper blade starts the wiping operation, and at a point away from the initial position, the individual contact 30b is conductive, the wiper blade finishes the wiping operation, and then returns to the initial position. At the time when the contact is restored to the above state.

The individual contact 30a is grounded together with the ground terminal 5c of the wiper motor 5, and the individual contact 30b is
It is connected to the power supply line L2. Common contact 3
0c is connected to the individual contact 28a of the relay switch 28 via the line L4,
The potential 0c is detected by the processing circuit 12 from the line L5 via the signal processing circuit 31. Processing circuit 12
Determines from the detected potential of the common contact 30c whether or not the wiper blade is performing the wiping operation.

Therefore, when driving the wiper motor 5 at a low speed, the processing circuit 12 outputs a drive signal from the output terminal P2 to the line L3. As a result, the transistor Tr2 is turned on, the relay coil 27 is excited, and the contacts 28b and 28c of the relay switch 28 are turned on.
Therefore, the battery 23 via the power line L2
Is supplied to the low-speed power input terminal 5a of the wiper motor 5 from the contacts 28b and 28c via the contacts 24c and 24a of the relay switch 24.

In this way, when the wiper motor 5 is started and the cam switch 30 is switched from the individual contact 30a to the individual contact 30b, and then the wiper blade returns to the initial position, the cam switch 30 is switched from the individual contact 30b to the individual contact 30a again. , The processing circuit 12 stops outputting the driving signal. As a result, the brake current flows to the low-speed power input terminal 5a of the wiper motor 5 through the contacts 30a and 30c, the contacts 28a and 28c of the relay switch 28, and the contacts 24c and 24b of the relay switch 24, and the wiper motor 5 stops. I do.

When driving the wiper motor 5 at a high speed, the processing circuit 12 outputs a drive signal from the output terminals P1 and P2, whereby the transistors Tr1 and Tr2 are output.
Are conducted, the relay coils 22 and 27 are both excited, the relay switch 24 is conducted to the individual contact 24b, and the relay switch 28 is conducted to the individual contact 28b. Thus, the electric power from the battery 23 is supplied to the high-speed power input terminal 5b of the wiper motor 5 via the relay switches 28 and 24.

The processing circuit 12 detects from the output voltage level of the cam switch 30 whether or not the wiper blade has returned to the initial position. Until the wiper blade returns to the initial position, the processing circuit 12 outputs the signal from the output terminals P1 and P2. Continue to derive drive signals. Thus, the wiper motor 5 can be driven at a low speed and a high speed.

In the processing circuit 12, counters 32, 3
3, the counter 32 is provided with the output terminal P
At the point in time when the output of the drive signal from 2 is stopped, the timer operation is started, and the intermittent time WOT is counted. The counter 32 determines that the integrated values M1 and M2 are equal to threshold values RP and
It is reset at the time when it becomes RN or more or when the intermittent time WOT elapses. Further, the counter 33 integrates the number M2 of output pulses from the raindrop sensor 4.

FIG. 4 is a flowchart for explaining an automatic wiper control operation according to one embodiment of the present invention. When the automatic wiper switch 2 is turned on, the process proceeds to step n1, where the integrated values M1 and M2 are initialized, and the intermittent time W is set.
Initialization processing such as setting of an initial value of the OT is performed.

At step n2, the number M2 of output pulses from the raindrop sensor 4 is integrated, and when a pulse is derived, the count value of the counter 33 is updated by adding one. In step n3, it is determined whether or not the count value has reached a predetermined threshold value RN, for example, 8 or more. If not, the process proceeds to step n4.

In step n4, when the output pulse is derived, the pulse width is integrated to obtain an integrated value M1. In step n5, the integrated value M1
Is determined to be not less than a threshold value RP, for example, 0.2 sec. If not, the process proceeds to step n6.

In step n6, the count value WCT of the counter 32 is incremented by 1 to perform a counting operation. In step n7, it is determined whether or not the count value WCT has become equal to or longer than the intermittent time WOT. The process returns to step n2, and if so, ie, when the time threshold has elapsed, the process proceeds to step n8.

In step n8, it is determined whether or not the integrated value M1 is less than a value MDN which is 1/2 of the threshold value RP. If so, the process proceeds to step n9, and the step of the intermittent time WOT is one step. And the intermittent time is changed to be longer. Otherwise, step n10
The step of the intermittent time WOT is maintained.

When the integrated value M1 exceeds the threshold value RP in step n5, that is, when the integrated value M1 exceeds the pulse width threshold value, the process proceeds to step n11, where the count value WC is set.
It is determined whether or not T is within the time WUP that is 80% of the intermittent time WOT, and if so, step n1
In step 2, the step of the integrated value WOT is increased by one step, that is, the intermittent time is changed to be short, and if not, the process proceeds to step n10 and the step of the intermittent time WOT is held. When the integrated value M2 of the number of pulses is equal to or larger than the threshold value RN in step n3, that is, when the pulse number exceeds the threshold value, the process proceeds to step n10, and the step of the intermittent time WOT is held.

Thus, steps n9, n10 and n1 are performed.
When the step of the intermittent time WOT is selected in step 2, the process proceeds to step n21, and the next intermittent time WOT is set in the selected step. In step n22, the count values of the integrated values M1, M2 and the time WCT are reset to zero.

In step n23, a drive signal is selectively output from the terminals P1 and P2 of the processing circuit 12, and the wiper motor 5 is started. At step n24, it is determined whether or not the common contact 30c of the cam switch 30 has been switched to the individual contact 30b, that is, whether or not the wiper blade has left the initial position and has started the wiping operation. Move on to In step n25,
The common contact 30c of the cam switch 30 is
a, that is, whether or not the wiping operation has been completed.
Move to 26. In Step n26, the output of the drive signal is stopped, and after the wiper motor 5 is stopped, the process returns to Step n2.

Therefore, if the steps n2 and n3 are not provided, even if the forward visibility deteriorates due to raindrops having a very small diameter such as drizzle or jumped-up raindrops, the integrated value M1 of the pulse width obtained at the step n4 is not changed. n5 does not exceed the threshold value RP, and thus the intermittent time WOT becomes longer each time the intermittent time WOT elapses.

On the other hand, as in the present invention, step n
When the integrated value M2 is equal to or larger than the threshold value RN in which the forward visibility is deteriorated, the step of the intermittent time WOT is held.
Since the wiping operation of the wiper blade is performed, even when the forward visibility is deteriorated by the extremely small diameter raindrop as described above,
The wiping operation can be performed with good responsiveness. This allows the driver to conduct the wiper operation at an optimal wiping interval that matches the driver's feeling even for extremely small raindrops by merely turning on the auto wiper switch 2 without performing complicated operations. Operability can be improved.

On the other hand, the raindrop sensor 4 is arranged at a distance from a windshield, which is a region where rainfall is to be detected, such as a hood or a front grill of an automobile, and the light path 4c is smaller than the area of the windshield. As shown in FIG. 5, raindrops are missed due to such a narrow detection range.

In the above embodiment, at the time of extremely light rain, the wiping operation is performed when eight or more raindrop pulses, which are the threshold value RN, are inputted. Therefore, at time t1, t2,
, When a raindrop pulse is detected as indicated by reference numerals q1, q2,..., The eighth raindrop pulse q
At a time t8 when 8 is detected, the wiping operation of the wiper blade is performed. However, as is apparent from FIG. 5, for example, the interval W12 between the raindrop pulses q1 and q2,
Compared to the interval W45 between the raindrop pulses q4 and q5 and the interval W56 between the raindrop pulses q5 and q6, the raindrop pulse q6
The interval W67 between q7 is very long and therefore the reference q
As shown by 11, q12,..., It is considered that raindrops are missed due to the narrow detection range. For this reason, in another embodiment of the present invention, the raindrop pulse at an interval shorter than the predetermined interval Wa is equal to the threshold R.
When Na, for example, three or more raindrops are detected, that is, when the frequency of raindrops is high, the wiping operation is performed when the third raindrop pulse is detected.

Therefore, in FIG. 5, the raindrop pulse q2 detected from the raindrop pulse q1 at the interval W12 shorter than the interval Wa is the first pulse.
The pulses q5 and q6 detected at intervals W45 and W56 shorter than the interval Wa become the second and third pulses, respectively, and the wiping operation is performed at time t6 when the third pulse q6 is detected.

FIG. 6 is a flow chart for explaining the automatic wiper control operation of another embodiment of the present invention shown in FIG. 5 described above, and is similar to the embodiment shown in FIG. Have the same reference numerals. In this embodiment, in step n1a, together with the integrated values MI and M2 and the count value WCT, a flag F1,
After F2 and the count value M2a are reset to zero,
Move to step n31.

At step n31, it is determined whether or not the flag F1 representing the generation of a raindrop pulse is set to 1. If not, that is, if no raindrop pulse has been detected in the previous calculation processing, the flow goes to step n3.
Move to 2. In step n32, it is determined whether or not a raindrop pulse has been generated at the current arithmetic processing timing. If not, the pulse generation flag F1 is reset to zero in step n33, and the process proceeds to step n2. In some cases, after the pulse generation flag F1 is set to 1 in step n34, the process proceeds to step n2.

In step n31, when a raindrop pulse has been detected at the previous calculation processing timing, the process proceeds to step n35, where it is determined whether or not the interval Wa, for example, within 0.5 sec, has been detected since the previous pulse was detected. If not, the flow proceeds to step n2 after the pulse generation flag F1 is reset to zero in step n36, and otherwise proceeds to step n37.

At step n37, it is determined whether or not a raindrop pulse has been generated this time following the previous time. If not, the process proceeds to step n2. If so, the process proceeds to step n38. The count value M2a is updated by being incremented by one. At step n39, the count value M2 at step n38 is obtained.
It is determined whether or not a is equal to or greater than the threshold value RNa. If so, the pulse generation flag F1 and the integrated value M2a are reset to zero in step n40, and then the process proceeds to step n10, where the step of the intermittent time WOT is performed. Is retained. In addition, from step n40 to step n
Moving to 12, the intermittent time WOT may be changed to be shorter.
On the other hand, when the integrated value M2a is less than the threshold value RNa in step n39, the process returns to step n31 and continues counting until the time Wa elapses.

Therefore, in this embodiment, the raindrop sensor 4
, The wiper blade can be driven at the wiping interval that further matches the driver's feeling by compensating for the amount of missed reading of raindrops due to the narrow detection range.

[0050]

As described above, according to the present invention, the output pulse from the raindrop sensor is integrated by the pulse width and the number of pulses, and a threshold value is provided for each integrated value. The wiping operation is performed when the integrated value of the pulse width is equal to or more than the threshold value, and the wiping operation is performed when the number of pulses is equal to or more than the integrated value during extremely small rain such as drizzle or jumped raindrops. Thus, the driver can always maintain a good forward visibility even in the case of extremely light rain, without performing complicated operations such as temporarily switching to manual operation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a wiper control device 1 according to one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the raindrop sensor 4;

FIG. 3 is a diagram showing a threshold value of a step change of an intermittent time WOT.

FIG. 4 is a flowchart for explaining an automatic wiper control operation according to one embodiment of the present invention.

FIG. 5 is a timing chart for explaining the operation of another embodiment of the present invention.

FIG. 6 is a flowchart for explaining an automatic wiper control operation shown in FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 wiper control device 2 automatic wiper switch 3 control circuit 4 raindrop sensor 5 wiper motor 12 processing circuit 32, 33 counter

Claims (2)

(57) [Claims] 1. A raindrop sensor for detecting a rainfall state, a driving means for reciprocally driving a wiper blade for removing raindrops attached to a surface to be wiped on the surface to be wiped, and an output pulse from the raindrop sensor Are integrated by the pulse width and the number of pulses, respectively, and a predetermined threshold value is provided for each integrated value, and either one of the integrated values reaches the corresponding threshold value first, and Control means for outputting a drive signal indicating that the wiper blade should be driven to the drive means, at the earlier of the time at which the predetermined intermittent time has elapsed since the end of the previous wiping operation of the wiper blade; and And a wiper control device. 2. The method according to claim 1, wherein the control unit is configured to determine a time required for one of the integrated values to reach the corresponding threshold value first, the integrated value when the intermittent time has elapsed, At least one of the pulse frequency of the pulse
2. The wiper control device according to claim 1, wherein the intermittent time is updated based on one of the following.