JPH04339050A - Wiper control device - Google Patents

Abstract

PURPOSE:To drive a wiper blade with an optimum interval which is in harmony with a driver's feeling by measuring the required period of time for the wiping operation of the wiper blade, and making correction of the threshold to drive the wiper blade on the basis of the measured results. CONSTITUTION:Integration is made on the value based on the output of a raindrop sensor 4, and the wiping operation of a wiper blade is achieved when the integrated value (M) is equal to or more than the preset threshold TH, and the wiping operation is achieved automatically with a wiping interval appropriate for the raining condition. When the condition where the actually-measured time W1 required for wiping exceeds the standard time W2 required for wiping in response to the voltage of a battery 23 consecutively three times, a judgement is made that water-less wiping operation is achieved, then the threshold TH is changed to a larger value and correction is made so as to lengthen the intermittent time.

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 suitable for use in a vehicle, which drives a wiper blade at a wiping interval suitable for rainy conditions.

0002

[Background Art] A so-called automatic wiper control device that controls wiper operation based on the output of a raindrop sensor integrates the output of the raindrop sensor, and when the integrated value exceeds a predetermined threshold, starts the wiping operation of the wiper blade. let

[0003] The integration operation is configured to be started, for example, after the wiper blade has finished its wiping operation. Also, for example, the integration operation is paused until the wiper blade reaches the return position from the initial position, and the integration operation is performed by multiplying by a factor of 1/2 until the wiper blade returns from the return position to the initial position, and after the wiper blade ends, the integration operation is performed. The configuration is such that the value based on the output of the raindrop sensor is directly integrated by multiplying by a coefficient 1.

[0004] In typical conventional technology, such sensitivity adjustment of an auto wiper control device is achieved by using a variable resistor in a voltage dividing resistor circuit that generates a threshold voltage and changing the resistance value of this variable resistor. ing. In another conventional technique, the sensitivity adjustment is realized by counting pulses from the raindrop sensor using a microcomputer and increasing or decreasing the number of threshold pulses for level discrimination of the counted value.

[0005]

[Problem to be solved by the invention] In the above-mentioned prior art,
Detection sensitivity is determined by changing the threshold value. On the other hand, the detection range of the raindrop sensor is extremely narrow compared to the area of the windshield, so even under the same rainfall condition, the detection results vary. Furthermore, rainfall conditions change from moment to moment.

Furthermore, even if the detection sensitivity is adjusted as described above, the wiping operation is not necessarily performed with the desired characteristics.
In addition, this wiping operation characteristic is not fed back,
For this reason, it is extremely difficult to drive the wiper blade at a wiping interval that matches the sense of the driver, who is the operator.

That is, for example, the battery voltage fluctuates from 11V when the engine is stopped to 15V when the engine is running, and as a result, the wiping operation time of the wiper blade is
The standard time is 1 to 1.5 seconds, and it fluctuates by 50 to 70%. In addition, the wiping operation time is 1% longer than the above standard time depending on the state where too many raindrops have accumulated and the state where the wiping is dry.
It changes by about 0%. Due to changes in the wiping operation time due to such factors, the start timing of the integration operation as described above changes, resulting in a difference from the driver's sense.

[0008] An object of the present invention is to provide a wiper control device that can drive a wiper blade at an optimal wiping interval that matches the sense of the driver.

[0009]

[Means for Solving the Problems] The present invention integrates a value based on the output of a raindrop sensor that detects the rain state, and when the integrated value exceeds a predetermined threshold, the wiper blade is driven to remove the deposits on the surface to be wiped. The wiper control device includes a detection means for detecting whether or not the wiper blade is in a wiping operation, and a detection means for detecting whether or not the wiper blade is in a wiping operation, and a time required for the wiping operation of the wiper blade in response to a detection result of the detection means. The wiper control device is characterized in that it includes a correction unit that measures the threshold value and corrects the threshold value based on the measurement result.

0010

[Operation] According to the present invention, the value based on the output of the raindrop sensor is accumulated after the wiper blade finishes its wiping operation, or the accumulation is performed from the initial position to the return position after the wiper blade starts its wiping operation. is paused, and the coefficient 1/2 is multiplied and integrated until the return position is returned from the turning position to the initial position, and after the wiping operation is completed, the coefficient 1 is multiplied and integrated. Thereafter, when the integrated value exceeds a predetermined threshold value, the wiper blade is driven, and raindrops adhering to the surface to be wiped, such as the windshield, are removed.

[0011] Therefore, for example, in connection with the wiper motor, a detection means such as a cam switch whose switching state changes between a state in which the wiper blade is at its initial position and a state in which it is separated from its initial position is provided. The detection means detects whether the wiper blade is in a wiping operation.

The detection result of the detection means is given to a correction means, and the correction means measures the time required for the wiping operation of the wiper blade in response to the detection result. When the measurement is completed, the correction means determines that if the measurement result continues for a predetermined number of times longer than the standard required time, the number of raindrops adhering to the surface to be wiped is very small and the wiped surface is in a dry wiping state. Then, the threshold value is greatly corrected and the intermittent time is changed to be longer.

In this way, the time required for the wiping operation, which varies depending on the battery voltage and the state of adhesion of raindrops, is fed back to the threshold value correction, and the wiper blade is driven at an optimal wiping interval that matches the sense of the driver.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the electrical configuration of a wiper control device 1 according to an embodiment of the present invention. This wiper control device 1 is used for vehicle use, and by turning on an auto wiper switch 2, a control circuit 3 drives and controls a wiper motor 5 in response to a detection signal from a raindrop sensor 4, thereby controlling a wiper blade (not shown). This is a so-called automatic wiper control device that performs a wiping operation by reciprocating the wiper on the windshield.

The raindrop sensor 4 is an optical sensor that includes, for example, a pair of light receiving and emitting elements, and detects the amount of rainfall based on a change in the level of light received when the raindrops pass through an optical path formed by the light receiving and emitting elements. This is a raindrop sensor. The detection signal from the raindrop sensor 4 is input to the control circuit 3, and after being shaped into a rectangular wave pulse by the waveform shaping circuit 11, the processing circuit 12 is realized by a microcomputer or the like.
is input. Further, the output of the auto 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 .

When the auto wiper switch 2 is turned on, the processing circuit 12 reads the detection signal from the raindrop sensor 4 and sets the operating state of the wiper motor 5. That is, when the amount of rainfall is small, the intermittent operation state is set, and as the amount of rainfall increases, the intermittent time is set to be shorter. Furthermore, when the amount of rainfall exceeds a predetermined level, the system enters a low-speed continuous operation state. When the amount of rainfall increases further and exceeds a predetermined level, a high-speed continuous operation state is set. In this way, the auto wiper control is realized.

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. This drive signal is applied to the base of the transistor Tr2 via a resistor R3 and a 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. This power line L2 is connected to a high level terminal of the battery 23.

Power from the battery 23 is also supplied to the processing circuit 12, raindrop sensor 4, etc. via a constant voltage circuit 29. The processing circuit 12 reads the voltage of the battery 23, which is the drive voltage of the wiper motor 5, via the analog/digital converter 14.

On the other hand, the relay switch 2 of the relay 26
8 is provided with two individual contacts 28a and 28b, one individual contact 28b is connected to the power supply line L2, and the other individual contact 28a is connected to the common contact 30c of the cam switch 30 via the line L4. There is. Also relay 2
The common contact 24c of the first relay switch 24 is connected to the individual contact 28c of the relay switch 28, and the individual contact 24a
is connected to the low speed power input terminal 5a of the wiper motor 5.

The processing circuit 12 also outputs drive signals from output terminals P1 and P2 to lines L1 and L3 when driving the wiper motor 5 continuously at high speed. Said line L1
The drive signal is transmitted to the transistor Tr via resistors R1 and R2.
The drive signal on line L3 is input to the base of transistor Tr2 via resistors R3 and R4.

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

A cam switch 30 as a detection means is provided in connection with the wiper motor 5. When the wiper blade is in the initial position, the cam switch 30 is electrically connected to the individual contact 30a. is activated, the wiper blade starts the wiping operation, and conducts to the individual contact 30b when it leaves the initial position, and when the wiper blade finishes the wiping operation and returns to the initial position again, the individual contact 30a conducts to.

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. Also common contact 3
0c is connected to the individual contact 28a of the relay switch 28 via line L4, and this common contact 3
The potential of 0c is detected by the processing circuit 12 via the signal processing circuit 31 from the line L5. Processing circuit 12
determines whether the wiper blade is in the wiping operation based on the detected potential of the common contact 30c.

Wiper control device 1 configured as described above
When driving the wiper motor 5 at 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 becomes conductive, the relay coil 27 is excited, and the contacts 28b and 28c of the relay switch 28 are brought into conduction. therefore,
Electric power from the battery 23 via the power line L2 is supplied to the low-speed power input terminal 5a of the wiper motor 5 via contacts 24c and 24a of the relay switch 24.

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 the wiper blade returns to its initial position, the cam switch 30 is switched from the individual contact 30b to the individual contact 30a, and the processing circuit 12 stops outputting the drive signal. As a result, a brake current flows through the contacts 30a, 30c from the contacts 28a, 28c of the relay switch 28 to the contacts 24c, 24b of the relay switch 24 to the low speed power input terminal 5a of the wiper motor 5.
stops.

Further, when driving the wiper motor 5 at high speed, the processing circuit 12 outputs a driving signal from the output terminals P1 and P2, thereby causing the transistors Tr1 and Tr2 to
conducts, relay coils 22 and 27 are both excited, relay switch 24 conducts to individual contact 24b, and relay switch 28 conducts to individual contact 28b. Thereby, 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.

Processing circuit 12 is responsive to the output voltage level of cam switch 30 and continues to derive the drive signal from output terminals P1 and P2 until the wiper blade returns to the initial position. In this way, the wiper motor 5 can be driven at low speed and high speed.

Furthermore, timers 32 and 3 are provided in the processing circuit 12.
3 is built-in, and the timer 32 is connected to the output terminal P1.
, P2 starts the timing operation, and measures a predetermined time T1, which will be described later. The time required for the wiping operation is measured.

FIG. 2 is a timing chart for explaining the integration operation of the detection signal of the raindrop sensor 4 in the processing circuit 12. It is assumed that the rainfall condition is constant. When the processing circuit 12 starts the wiper motor 5 at time t1, the wiper blade starts a wiping operation, as shown in FIG. 2(4). At this time, the timer 32 starts counting operation after being set to the time T1 as shown in FIG. 2(2), and the timer 33 starts timing operation as shown in FIG. 2(3). Further, at this time, the processing circuit 12 operates as shown in FIG.
As shown in (1), after the cumulative amount M of rainfall is reset to 0, the cumulative operation is stopped.

After the wiper motor 5 is started as described above, at time t2 when the count value of the timer 32 becomes 0 as shown in FIG. 2(2), the wiper blade is moved as shown in FIG. 2(4). It has reached the turning point. From this time t2, the processing circuit 12 starts integrating 1/2 of the detection signal level of the raindrop sensor 4, as shown in FIG. 2(1).

When it is detected from the output voltage level of the cam switch 30 that the wiper blade has completed its wiping operation and returned to the initial position, as shown in FIG. 2(4), the processing circuit 12 As shown in Figure 2 (1),
From that time t3, the detection signal of the raindrop sensor 4 is directly integrated. At this time, the timer 33 ends its time counting operation. Further, the time T1 is selected so as to be 1/2 of the required time W1 for wiping the wiper blade, which is the time measurement result of the timer 33.

At time t4 when the integrated value M reaches the predetermined threshold TH, the wiping operation of the wiper blade is started as shown in FIG.
2), the timer 32 again returns the time T.
The timer 33 is set to 1 and starts a timekeeping operation, and the timer 33 is reset to zero and starts a timekeeping operation.

The processing circuit 12, which is also a correction means,
When performing the wiper control operation as described above, the threshold value TH is corrected in accordance with the wiping operation state of the wiper blade. That is, first, the voltage of the battery 23 is read through the analog/digital converter 14, and corresponding to that voltage, the data of the standard required wiping time W2 shown in Table 1 is calculated by interpolation. Next, the actual required wiping time W1 measured by the timer 33 and the standard required wiping time W2
For example, when W1≦W2, it is determined that the wiping operation is being performed within the standard required wiping time W2 corresponding to the voltage of the battery 23, and the threshold TH is held.

[0034]

[Table 1]

On the other hand, when the state of W1>W2 continues for a predetermined period or longer, it is determined that the wiper blade is in a dry wiping state where the frictional resistance between the wiper blade and the windshield is large, and the threshold value TH is set for a long time. Correct it so that it is correct.

FIG. 3 is a flowchart for explaining the wiper control operation including the above-mentioned operation for correcting the threshold value TH. When the auto wiper switch 2 is turned on,
In step n1, an initialization process is performed in which a standard value, for example, 60 msec, is substituted for the threshold TH, and a dry wiping determination flag F1, which will be described later, is reset to zero.

In step n2, the detection signal Ma of the raindrop sensor 4 is added to the integrated value M to perform an integrating operation, and in step n3, it is determined whether or not the integrated value M has exceeded the threshold TH. If not, step n2
Returning to step n4, the integration operation is repeated, and if yes, the process moves to steps n4 and subsequent steps, where the wiper blade is caused to perform a wiping operation and the threshold value TH is corrected.

At step n4, the voltage of the battery 23 is read through the analog/digital converter 14, and at step n5, the standard wiping time W2 corresponding to the read voltage is read from Table 2.

At step n6, the timer 33 is activated. In step n7, output of drive signals is started from the output terminals P1 and P2, and the wiper motor 5 is activated. In step n8, the common contact 30 of the cam switch 30
The wiper blade waits until the potential of c becomes high level, that is, until the wiper blade leaves the initial position, and when it leaves the initial position and starts the wiping operation, the process moves to step n9.

In step n9, the wiper blade waits until the potential of the common contact 30c becomes low level, that is, until the wiper blade returns to the initial position and completes the wiping operation, and when the wiper blade returns to the initial position, the process moves to step n10. The output of the drive signal is stopped, and the wiper motor 5 is stopped. At this time, the counting operation of the timer 33 is stopped at step n11.

[0041] In step n12, the steps n6 to
It is determined whether the required wiping time W1 measured during n11 is less than or equal to the standard required wiping time W2 read in step n5, and if so, that is, raindrops have properly adhered to the windshield. Step n
Step 13, the threshold TH is maintained at the same value,
Furthermore, after the dry wiping determination flag F1 is reset to zero in step n14, the process returns to step n2.

In the step n12, when the actual wiping time W1 exceeds the standard wiping time W2, the process moves to step n15, and the dry wiping determination flag F1 is set.
It is determined whether or not is 1. If not, that is, if there is a possibility that too many raindrops have accumulated, the process moves to step n16, where a predetermined value α, for example, 15 msec, is subtracted from the threshold TH and updated. step n
In step 17, it is determined whether or not the negative correction of the threshold value TH in step n16 has been performed three times in a row. If not, it is determined that too many raindrops have accumulated and the process returns to step n2, and if so, the process returns to step n2. It is determined that the required wiping time W1 exceeds the standard required wiping time W2 due to dry wiping, and after the dry wiping determination flag F1 is set to 1 in step n18, the process returns to step n2.

In this way, when the negative correction of the threshold value TH in step n16 is performed three times in a row, the process moves from step n15 to step n19, where the threshold value TH is updated by adding a predetermined value β, for example, 25 msec. , return to step n2.

As described above, the wiper control device 1 according to the present invention
Then, when the required wiping time W1 of the wiper blade measured by the counter 33 is less than or equal to the standard required wiping time W2 determined in accordance with the voltage of the battery 23, it is determined that the amount of raindrops attached is appropriate, and the above-mentioned threshold value is determined. Hold TH. On the other hand, when the required wiping time W1 exceeds the standard wiping time W2, it is first determined that too many raindrops have accumulated than the appropriate amount, and the threshold value TH is corrected to be shorter, and such negative correction is performed. If this is not effective, it is determined that the required wiping time W1 has become longer due to an increase in frictional resistance due to dry wiping, and the threshold value T
Correct H so that it becomes longer.

Therefore, even if the required wiping time W1 changes due to variations in the battery voltage and the amount of raindrops attached, the threshold value TH changes in accordance with the change, so the detection range of the raindrop sensor 4 is relatively narrow. Even if the detection results vary due to this, the wiper blade can be driven at an optimal wiping interval that matches the driver's sense.

[0046] Furthermore, when the wiper blade starts the wiping operation, the integration operation is stopped until the wiper blade reaches the return position, and the integration is performed by multiplying by a coefficient 1 until the wiper blade returns to the initial position from the return position. After the wiping operation is completed, the coefficient becomes 1.
By multiplying and integrating the amount of raindrops, it is possible to accurately detect the amount of raindrops that adhere to the windshield after the wiper blade completes its wiping operation, which also allows for optimal wiping that matches the driver's senses. Wiper blades can be driven and controlled at intervals.

The control circuit 3 includes, for example, an LO switch that drives the wiper blade continuously at low speed, a HI switch that drives the wiper blade continuously at high speed, and an INT switch that drives the wiper blade at predetermined intervals, and is widely used. A control circuit may be used in which a configuration for automatic wiper control such as the above-mentioned processing circuit 12 and raindrop sensor 4 is added to the existing wiper switch as a so-called retrofit. In this case, the automatic wiper switch 2 can be replaced with an INT switch. can do.

[0048]

As described above, according to the present invention, when the values based on the output of the raindrop sensor are integrated, and the integrated value exceeds a predetermined threshold value, the wiper blade is activated. Since the time required for the wiping operation is fed back to the correction of the threshold value, the threshold value changes to follow the integrated value that is affected by the time required, which varies depending on the battery voltage, the state of raindrops, etc. The wiper blade can be driven at an optimal wiping interval that matches the sense of the driver.

[Brief explanation of drawings]

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

[Figure 2] Wiping operation of wiper blade and raindrop sensor 4
3 is a timing chart for explaining an operation of integrating detection signals in FIG.

FIG. 3 is a flowchart for explaining auto wiper control operation.

[Explanation of symbols]

1 Wiper control device 2 Auto wiper switch 3 Control circuit 4 Raindrop sensor 5 Wiper motor 12 Processing circuit 30 Cam switch 32, 33 Timer

Claims (1)

[Claims] 1. A wiper control device that integrates a value based on the output of a raindrop sensor that detects a rainfall state, and when the integrated value exceeds a predetermined threshold value, drives a wiper blade to remove raindrops adhering to a surface to be wiped. a detection means for detecting whether or not the wiper blade is in a wiping operation; and a detection means for measuring the time required for the wiping operation of the wiper blade in response to a detection result of the detection means, and based on the measurement result. A wiper control device comprising: a correction means for correcting the threshold value.