JP2000137899A - Inter-vehicle distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a measured error to the light of a vehicle to be a minimum at night even if dispersions occur in the assembly error of an optical sensor array and the amplification rate of an AGC amplifier. SOLUTION: For exposing an optical sensor array 64, an exposure control part 78 starts the exposure of the optical sensor array and monitor PD 75 and the exposure of the optical sensor array is terminated with the output of a comparator 77 when an exposure level S72 from monitor PD reaches a target exposure level S71. The exposure time is measured by an exposure time measuring timer 84 and day/night are judged by a day/light judgement part 83 from the length of measuring time. When the judged result is night, short time required for measuring the light is set as compulsory exposure termination time and the gain of an amplifier 68 is set to be low. The exposure of the optical sensor array is compulsorily terminated with the lapse of compulsory exposure termination time before the exposure of the optical sensor array is terminated based on the exposure level of monitor PD after the start of exposed and a difference between image data of the right/left optical sensor arrays on the light is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance measuring device used for preventing a collision accident of an automobile. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0002]

2. Description of the Related Art First, a prior art of an inter-vehicle distance measuring device for measuring a distance from a preceding vehicle will be described. 2. Description of the Related Art As a conventional inter-vehicle distance measuring apparatus, an apparatus that electrically compares images formed by two right and left optical systems and measures a distance based on the principle of triangulation is known.

FIG. 9 is a block diagram showing a conventional inter-vehicle distance measuring apparatus 50 of this kind.
1 and a pair of imaging means 52 for imaging
Computing means 53 for calculating the distance from the image obtained by the above to the object 51 for distance measurement. The imaging means 52 includes a pair of imaging lenses 61 and 62 and a pair of optical sensor arrays 6.
The arithmetic means 53 comprises a signal processing unit 65 and a distance detection circuit 66.

In FIG. 9, image forming lenses 61 and 62 are arranged with an optical axis interval B therebetween. The optical sensor array 6
3 and 64 are, for example, CCD linear sensor arrays,
Each is disposed at a position of a focal length f with respect to the imaging lenses 61 and 62. These optical sensor arrays 63 and 64 are used for measuring the distance measurement target 5 formed by the imaging lenses 61 and 62, respectively.
1 is converted into image signals S61 and S62, and the signal
5 is output.

The signal processing unit 65 has an automatic gain control (AG
C) It comprises amplifiers 67 and 68 with functions, A / D converters 69 and 70, and a storage device 71. Optical sensor array 6
The image signals S61 and S62 from the A / D converters 69 and 70 are amplified by amplifiers 67 and 68, respectively.
Is converted into digital data by the
The data is output to the storage device 71 as 3L and 64R.

The distance detection circuit 66 provided on the output side of the signal processing section 65 is constituted by a microcomputer, and stores the left and right image data 63 stored in the storage device 71.
The distance to the distance measurement target 51 is calculated by comparing L and 64R, and output to the outside as a distance signal S65.

Next, the principle of distance detection will be described with reference to FIG. The midpoint between the optical axes of the imaging lenses 61 and 62 is defined as the origin O
, The horizontal axis X and the vertical axis Y are set, and the coordinates of the imaging positions L ₁ and R ₁ are (−a _L1 −B / 2, −f) and (a _R1 + B /
2, -f). Here, a _L1 and a _R1 are distances on the optical sensor arrays 63 and 64 as shown.

[0008] coordinates of the center point O _L of the imaging lens 61 (-
B / 2, 0), the coordinates of the center point O _R of the imaging lens 62 is a (B / 2, 0), if the coordinates of point M measuring object 51 (x, y) and the point Vertical line from M to X axis and X
The coordinates of the intersection N with the axis are (x, 0), and the coordinates of the position L ₀ of the perpendicular line lowered from the point _OL to the optical sensor array 63 are (−B /
2, -f), the coordinate position R ₀ of perpendicular dropped from the point O _R to the optical sensor array 64 is (B / 2, -f). In this case, the triangle MO _L N and a triangle O _{L L 1 L 0,} triangle M
Since O _R N and a triangle O _R R ₁ R ₀ are each similar, the following equation (1), (2) holds further formula (1) and (2)
The following equation (3) can be obtained from

[0009]

(X + B / 2) f = a _L1 · y (1) (−x + B / 2) f = a _R1 · y (2) y = B · f / (a _L1 + a _R1) ) (3) From this equation (3), the distance a with respect to the imaging positions L ₁ and R _{1
If L1} and _aR1 are known, the distance y to the distance measurement target 51 is y = L.
Can be calculated.

Next, the operation of the distance detection circuit 66 will be described in detail. The distance detection circuit 66 compares the left and right image data 63L and 64R as shown by the solid line in FIG. 11 for a separately set distance measurement range 73 (see FIG. 12). As shown by the broken line, for example, the left image data 63L is sequentially shifted to the right or the right image data 64R is sequentially shifted to the left, and the shift amount ((a _L1 + A _R1 ) is detected.

The distance detection circuit 66 calculates the shift amount (a _L1 +
a _R1 ), the distance y to the distance measurement target 51 is calculated by the above equation (3). FIG. 12 is a schematic diagram illustrating an image in a normal state when the inter-vehicle distance to the preceding vehicle 51a is detected. Here, a distance measurement range 73 is set within the measurement field of view 72 in FIG. 7, and the distance to the object within the distance measurement range 73, that is, the distance to the preceding vehicle 51a is detected as the inter-vehicle distance based on the principle of the distance detection described above.

In order to widen the field of view for detecting the object to be measured, a plurality of optical sensor arrays are arranged so that their lines (that is, the lines of the rows in which the CCD elements are arranged) are parallel to each other. A method of detecting a vehicle based on the vehicle and detecting an inter-vehicle distance is also disclosed in the prior application of the present applicant (Japanese Patent Laid-Open No. 10-621).
No. 63, an inter-vehicle distance measuring device).

FIG. 13 shows the principle of exposure control in the prior art for causing the photosensor array to perform appropriate exposure.
This will be described based on FIG. This figure shows a circuit related to the optical sensor array 64 on one side of the principle diagram shown in FIG. 9, and a circuit related to the paired optical sensor array 63 is configured similarly to the circuit in FIG.

In FIG. 13, a plurality of monitor PDs 75 each including a photodiode for detecting the brightness of the corresponding portion of the optical sensor array 64 are arranged in the vicinity of the optical sensor array 64 along the line of the optical sensor array 64. Have been. The monitor PD 75 selects an arbitrary monitor PD from a plurality of monitor PDs by switching a monitor PD changeover switch (the switch is also abbreviated to SW) 79 by a monitor PD range selection signal S69 from the control circuit unit 80. It is possible.

When the control circuit 80 outputs an exposure start signal S70 as an exposure start / forced end signal (exposure start signal or forced exposure end signal), the exposure start signal S70 is output.
70 is provided to the optical sensor array 64 and the selected monitor PD 75 via the exposure control unit 78, and the optical sensor array 64 and the monitor PD 75 start exposure.

The output signal (luminance signal) from the monitor PD 75 is amplified and integrated by the amplifier 76, and the exposure level S72 of the monitor PD 75 as the integrated value is set in advance by the comparator 77 and given from the control circuit unit 80. Is compared with the target exposure level S71.

When the exposure level S72 reaches the target exposure level S71 in this way, a signal indicating this is output from the comparator 77 to the exposure control unit 78, and the exposure control unit 78 sends the signal to the optical sensor array 64 and the monitor. The exposure is sent to the PD 75 to end the exposure. At the same time, the exposure end signal S65
Is output to the control circuit unit 80.

FIG. 5 shows the above-mentioned invention (Japanese Patent Application Laid-Open No.
In this example, the line selection switch 74 is set to a line selection signal S68 from the control circuit unit 80.
, It is possible to select and use the optical sensor array 64 of an arbitrary line from a plurality of lines. This makes it possible to independently control the lines of the plurality of optical sensor arrays. FIG. 5 shows the configuration on the optical sensor array 64 side.
Is configured similarly to FIG.

After the exposure is completed, the image signal S62 from the optical sensor array 64 is converted into a gain selection signal S
An AGC amplifier 68 whose gain has been set via the 67 amplifies the distance measurement target having a low luminance and a low contrast so that image data having a high contrast is obtained. The amplified image signal 40A is sent to the A / D converter 70 to become image data 64R, and thereafter processed in the same manner as described with reference to FIGS.

[0020]

However, the following problems may occur in the above-mentioned conventional technology. FIG. 14 is an explanatory diagram of this inconvenience. This figure shows a case in which lights such as a tail light and a headlight of a car are viewed by an optical sensor array at night and the distance from the superimposition of the images to the lights, that is, the distance between the vehicles is obtained.

The reference numeral 81L in FIG.
Is the range in which the vehicle is viewed, that is, the field of view of the optical sensor array. Similarly, 81R in FIG.
Represents the field of view.

Here, the two optical sensor arrays 63 and 64
Should be ideally coincident with each other in the horizontal direction, but in actuality, the optical sensor array 63 is not illuminated due to the assembly error of the optical sensor array as shown in FIGS. Looking at the center, the optical sensor array 6
In No. 4, inconsistency in the visual field in the horizontal direction occurs, such as viewing the end of the light. As a result, the light image data 63L of the light sensor array 63 and the light image data 64R of the light sensor array 64 greatly differ.

As a result, the left and right image data 63L and 64R do not match as shown in FIG. 14 (c), and a large error occurs in the detected shift amount. That is, the distance measurement error increases. The difference between the two images also appears as a larger difference due to the difference due to the variation in the amplification factor of the AGC amplifiers 67 and 68 connected to the optical sensor arrays 63 and 64, respectively. It gets bigger and bigger.

In order to solve this problem, it is conceivable to take measures such as increasing the assembly accuracy of the optical sensor array or reducing variations in the amplification factors of the individual amplifiers. This leads to an increase in the assembling time and an increase in the cost, and it is very difficult in practice to reduce the variation in the amplification factor of the amplifier, since this also leads to an increase in the cost of an amplifier selecting operation and an amplification factor correction circuit.

The problem to be solved by the present invention is to solve the above problems of the prior art and to reduce the distance between vehicles without being affected by nighttime lights, and to achieve a stable, simple and low-cost vehicle distance. It is to provide a measuring device.

[0026]

In order to solve the above-mentioned problems, a single line or a line is formed on an imaging plane of a pair of imaging lenses (61, 62) whose optical axes are parallel to each other and form an image on the same plane. A pair of light receivers composed of a plurality of rows of optical sensor arrays (63, 64, etc.) correspond to the respective imaging lenses, and are arranged so that the rows of the paired optical sensor arrays are respectively on the same straight line, The position shift (shift amount (a _L1 +) of the object image formed on the pair of optical sensor arrays (via the arithmetic means 53)
a _R1 )) is a device for detecting the distance to the object by triangulation from the _R 1).
Or a plurality of monitor photodiodes (monitor PD7
5), and the selected photosensor array and the selected monitoring photodiodes arranged in parallel with the photosensor array are simultaneously exposed (starting from the reception of the exposure start signal S70) to start exposure. When the exposure level of the photodiode for exposure (S72) reaches a preset target exposure level (S71), an exposure control unit (exposure control unit 78) for terminating exposure of the optical sensor array is provided. The inter-vehicle distance measuring device according to the first aspect of the present invention provides an exposure time (measured via an exposure time measurement timer 84 or the like) from the start to end of exposure of the optical sensor array based on the control of the exposure control means. (S76, S
73) day / night determining means (day / night determining unit 8)
3), a means for setting a forced exposure end time separately for the determined day and night (day / night determining unit 83), and after the exposure of the optical sensor array is started, the exposure is ended by the exposure control means (an exposure end signal S65 is output). If the forced exposure end time (T) elapses before the output is performed, the forced exposure stop for forcibly terminating the exposure of the optical sensor array (by sending a forced exposure end signal S70 to the exposure control unit 78, for example). (Control circuit unit 80).

According to a second aspect of the present invention, there is provided an inter-vehicle distance measuring apparatus according to the first aspect, wherein an image signal (S62) output from the optical sensor array according to the set forced exposure end time (T). The gain of the automatic gain control amplifier (AGC amplifier 68) for amplifying the
) (Control circuit unit 80).

Further, according to a third aspect of the present invention, the inter-vehicle distance measuring device determines day or night from the exposure time (S76, S73) from the start to the end of exposure of the optical sensor array based on the control of the exposure control means. Day / night determination means (day / night determination unit 83)
And a light control means (control circuit unit 80) for controlling ON / OFF of the headlight (85) and the taillight (86) according to the determined day and night.

According to a fourth aspect of the present invention, in the inter-vehicle distance measuring apparatus according to any one of the first to third aspects, the day / night determining means includes a measured exposure time (S
76, S73) is determined to be night when the length is longer than a predetermined determination time (Th), and is determined to be day when shorter.

According to a fifth aspect of the present invention, in the inter-vehicle distance measuring apparatus according to any one of the first, second and fourth aspects, the means for setting the compulsory exposure end time includes:
When the result of the day / night determination is night, a time (TS) short enough to allow the distance of the car light to be measured is set as the forced exposure end time (T), and the result of the day / night determination is determined. In the daytime, the time (TL) is sufficiently longer than the short time so that the distance of the low-luminance object can be measured.
Is set as the forced exposure end time (T).

According to a sixth aspect of the present invention, in the inter-vehicle distance measuring apparatus according to any one of the second, fourth and fifth aspects, the means for setting the gain may be configured such that the result of the day / night judging means is a night-time decision. If, set the gain to low magnification,
When the determination result of the day / night determining means is daytime, the gain is set to be at least higher than the low magnification so that the distance of the object having low luminance and low contrast can be measured.

According to a seventh aspect of the present invention, in the inter-vehicle distance measuring apparatus according to the third aspect, the day / night determining means further determines dusk from the exposure time, and the light control means determines the nightfall. ON / OFF of headlight and taillight according to the day, twilight, and night
FF is controlled.

According to a further aspect of the present invention, in the inter-vehicle distance measuring apparatus according to the seventh aspect, the day / night determining means determines whether or not the length of the measured exposure time (S76, S73) is a predetermined night time. If the time is longer than the time (Tn), it is determined to be night, and the length of the measured exposure time is equal to the night determination time (T
n) If it is shorter than a predetermined twilight determination time (Tg) which is shorter than the night determination time, it is determined to be twilight, and if the measured exposure time is shorter than the twilight determination time, it is determined to be day. To

According to a ninth aspect of the present invention, in the inter-vehicle distance measuring device according to any one of the third, fourth, seventh, and eighth aspects, the light control means determines whether the day / night determining means determines that the nighttime is a night. In this case, a signal for turning on both the headlight and the taillight (the headlight ON signal S77,
The tail light ON signal S78) is turned on by the day / night determining means, and when the result of the determination is dusk, the headlight is turned off and the tail light ON signal (head light OFF signal S77, tail light ON signal S78) is sent by the day / night determining means. If the determination result is daytime, a signal for turning off both the headlight and the taillight (the headlight OFF signal S
77, tail light OFF signal S78).

According to a tenth aspect of the present invention, there is provided an inter-vehicle distance measuring apparatus.
10. The inter-vehicle distance measuring device according to claim 9, wherein the headlight is a signal that turns on a headlight of a manually operated switch (headlight switch 91) and a signal that turns on the headlight of the light control unit. The tail light is turned on (via the headlight relay 87) under an OR condition (by an input to the circuit 89), and the taillight is turned on by a signal for turning on the taillight of a manually operated switch (taillight switch 92). Under an OR condition (by input to OR circuit 90) with a signal to turn on the tail light (via tail light relay 88)
Set to ON.

In the eleventh aspect of the invention, the following distance measurement apparatus is provided.
11. The inter-vehicle distance measuring device according to claim 1, wherein the selection of the selected photosensor array and the monitoring photodiode is performed by a changeover switch (by a control circuit unit 80).
D switching SW79), and the same exposure as described above is possible for each selection.

That is, the operation of the present invention is as follows. To perform exposure on the optical sensor array 64, the exposure control unit 78
, The exposure of the monitor PD 75 is started simultaneously with the optical sensor array, and the exposure level S72 obtained from the monitor PD
When exposure reaches the target exposure level S71, the exposure of the optical sensor array ends.

In the first invention, the time from the start of exposure to the end of exposure is measured by the exposure time measuring timer 84, and the day / night determining unit 83 determines day / night based on the length of the measuring time.

If the result of the determination is daytime, a time TL long enough to enable the measurement of the distance of the low-luminance object is set as the forced exposure end time T. If the result of the determination is night, A short time TS necessary and sufficient for measuring the distance of the vehicle light is set as the forced exposure end time T.

When the result of the determination is daytime, the control circuit 80 controls the AGC amplifier 68 so that a sufficient contrast of image data can be obtained even when measuring the distance of an object having low brightness and low contrast. Magnification is set higher than in the case of the night judgment result, and when the judgment result is night, AGC
A low magnification is set for the magnification of the amplifier.

Further, from the start of exposure of the optical sensor array by the control circuit section 80, the exposure level S7 of the monitor PD 75 is changed.
If the forced exposure end time T elapses before the exposure is completed based on the monitoring of 2, the forced exposure end signal S70 is transmitted to the exposure control unit 78, and the exposure of the optical sensor array is performed via the exposure control unit 78. Will be terminated.

Then, based on the set magnification of the AGC amplifier 68, the image signal S62 from the optical sensor array is amplified and A / D converted. A / D converted image data 64
The distance from R to the vehicle is detected by a distance detection circuit 66.

According to the second aspect of the present invention, the day / night determining unit 83 determines night and day, and further, night, dusk, and day, based on the exposure time measured as described above, via the exposure time measuring timer 84. .

If the result of this determination is night, a signal for turning on both the headlight 85 and the taillight 86 is provided. If it is dusk, a signal for turning off the headlight and the signal for turning on the taillight is provided. A signal for turning off the light and the tail light is transmitted. As a result, the headlight and taillight of the vehicle are automatically turned on and off according to night, dusk, and day.

[0045]

(Embodiment 1) First, an embodiment of the first invention will be described with reference to FIGS. FIG. 1 shows a circuit configuration of a main part relating to an optical sensor array 64 as one embodiment of the first invention. This figure has the same basic configuration as that of FIG. 13 described in the related art, except that an exposure time measurement timer 84 for measuring an exposure time and a day / night determination unit 83 are connected to the control circuit unit 80. Is a point.

The circuits of the main parts related to the optical sensor array 63 are configured in the same manner as in FIG. In the present invention, the control circuit unit 80 starts the exposure time measurement timer 84 at the timing of the start of exposure and the timing at which the exposure control unit 78 outputs the exposure end signal S65 based on the monitoring of the exposure level S72 of the monitor PD 75. And the exposure time is measured by transmitting the stop signal S75,
The measured exposure time S76 is transmitted as the exposure time S73 to the day / night determination unit 83 via the control circuit unit 80.

The day / night judging section 83 judges day / night from the length of the exposure time, and sends the judgment result and information S74 of the compulsory exposure end time T for the next exposure time measurement to the control circuit section 8.
Send to 0. The control circuit 80 selects the magnification of the AGC amplifier 68 based on the day / night determination result from the information S74 and the forced exposure end time T, and transmits the selected magnification to the AGC amplifier 68 as the gain selection signal S67.

Further, the control circuit unit 80 monitors the time from the start of exposure of the optical sensor array 64, and when the result of the day / night determination is night, it is necessary and short enough to measure the distance to the light of the car. If the exposure control unit 78 has not transmitted the exposure end signal S65 after the lapse of the fixed time T = TS, the exposure control unit 78 transmits a forced exposure end signal S70 as an exposure start signal / forced exposure end signal to the exposure control unit 78. This forcibly ends the exposure of the optical sensor array 64.

When the result of the day / night determination is day, the control circuit 80 sets the exposure control section 78 after a lapse of a predetermined time T = TL long enough to measure the distance of the low-luminance object.
If the exposure end signal S65 has not been transmitted from the controller, the forcible exposure end signal S70 is transmitted to the exposure control unit 78 to forcibly end the exposure of the optical sensor array 64.

Here, a series of operations of the control circuit unit 80, the exposure control unit 78, and the day / night determination unit 83 during exposure time measurement (referred to as exposure processing for convenience) in FIG. 1 will be described with reference to the flowchart of FIG. The algorithm of day / night determination in the day / night determination unit 83 in this flowchart will be described with reference to the flowchart of FIG.

First, FIG. 2 will be described. In addition, 100 ~
Reference numeral 123 denotes step numbers in the flowchart of FIG.
Reference numerals 1 to 115 denote step numbers of the exposure control unit 78 and 121 to 123 denote step numbers of the day / night determination unit 83 in the flowchart.

The exposure processing of FIG. 2 is constantly repeated in synchronization with the distance measurement processing. First, when the exposure processing is started (100), the control circuit unit 80 starts the exposure time measurement timer 84 at the start of exposure. A timer start signal S75 as a timer start / stop signal is transmitted to start the timer 84, and an exposure start signal S70 is transmitted to the exposure control unit 78 (101).

Upon receiving the exposure start signal S70, the exposure controller 78 immediately starts exposing the optical sensor array 64 and the monitor PD 75 (111). The control circuit unit 80 determines the day / night determination result and the information S74 on the forced exposure end time T determined and transmitted by the day / night determination unit 83 in the previous exposure processing.
Until the forced exposure end time T elapses from the exposure start time, it is monitored whether or not the exposure control unit 78 has transmitted the exposure end signal S65 (102, branch N → 10).
3, branch N → 102 loop).

If the exposure end signal S65 is transmitted during this period (103, branch Y), the process immediately proceeds to step 105, but the exposure end signal S65 is transmitted even after the forced exposure end time T has elapsed. Otherwise (10
2, branch Y), the forced exposure end signal S70 is
8 (104), and proceeds to step 105. When the exposure control unit 78 receives the forced exposure end signal S70 (1
12, branch Y), the exposure of the optical sensor array 64 and the monitor PD 75 is immediately forcibly terminated (114).

However, when the exposure control unit 78 does not receive the forced exposure end signal S70 (112, branch N), the exposure level S output from the monitor PD 75 via the amplifier 76
The comparator 77 determines that 72 has reached the target exposure level S71.
(113, branch Y), the exposure of the optical sensor array 64 and the monitor PD 75 is terminated, and the above-described exposure completion signal S65 is transmitted to the control circuit unit 80 (11).
4), return to step 100 for starting exposure again (11)
5).

The light sensor array 6 is exposed by this exposure.
4 is used by the AGC amplifier 68 with the magnification set by the control circuit unit 80 based on the information S74 of the compulsory exposure end time T transmitted from the day / night determination unit 83 in the previous exposure processing. Amplified.

The control circuit unit 80 determines in step 105
A timer stop signal S75 is transmitted to the exposure time measurement timer 84, the timer 84 is stopped, the exposure time S76 is received from the timer 84, and the received exposure time S76 is determined as the exposure time S73 in the next step 106 as the exposure time S73. Transmit to the unit 83.

Thus, the day / night determination section 83 makes a day / night determination based on the magnitude of the received exposure time S73 (12).
1), information S7 of day / night determination result and forced exposure end time T
4 is transmitted to the control circuit unit 80 (122), and the flow returns to step 100 for starting the exposure processing again (123).

The control circuit section 80 determines whether the day / night determination result transmitted from the day / night determination section 83 and the information S on the forced exposure end time T are provided.
AGC amplifier 68 to be applied to the next exposure based on 74
Set the magnification of. That is, if the forced exposure end time T transmitted in the current exposure processing is TS, the magnification of the AGC amplifier 68 is set to a low magnification.

If the transmitted forced exposure end time T is TL, sufficient magnification of the AGC amplifier 68 can provide sufficient image data contrast even when measuring the distance of a low-luminance, low-contrast object. A magnification larger than the low magnification is set. Then, a gain selection signal S67 indicating the set magnification is transmitted to the AGC amplifier 68 (10
7), and return to step 100 for starting the exposure processing again (10)
8).

The AGC amplifier 68 has a gain selection signal S6
7, the image signal S62 input from the optical sensor array 64 is amplified, and the image signal 4 is amplified.
Output as 0A. This image signal 40A is thereafter processed in the same manner as described in the prior art.

In the nighttime, as shown in FIG. 3, the forced exposure end time T is actually set to T = TS, which is a very short time for measuring the distance of the light of the car, and nighttime. In order to determine that the exposure level is low and to measure the distance of a low-luminance object (for example, a white line on the road) even at night (that is, the exposure control unit 78 performs the exposure based on the monitoring of the exposure level S72 of the monitor PD 75). T = T which is a long time (so that an end signal S65 can be output)
The setting of L is alternately repeated.

Even when the distance of a car light is measured, since the forced exposure end time T = TS is a very short time, before the exposure end signal S65 is transmitted from the exposure control unit 78 to the control circuit unit 80. The forced exposure end time T elapses. Therefore, in the nighttime, when T = TS is set, the exposure is usually forcibly terminated after the elapse of the forced exposure end time T.

In the daytime, the forced exposure end time T is T
However, unlike the TS, the TL is a sufficiently long time.
Exposure end signal S6 from exposure control unit 78 before elapse of
5 is transmitted. Therefore, in the daytime, the exposure is not usually forcibly terminated by the forced exposure end time T.

Next, the algorithm of the day / night judgment by the day / night judgment section 83 (step 121 in FIG. 2) will be described with reference to the flowchart in FIG. Note that 201 to 208 are shown in FIG.
Step numbers on the flowchart of FIG.

The day / night determining section 83 compares the exposure time S73 received from the control circuit section 80 with a predetermined determination time Th (Step 202).
3)> (determination time Th) (branch Y), it is determined to be night (203), and the process proceeds to step 204, while (exposure time S73) ≦ (determination time Th) (202, branch N). It is determined that it is noon (205), and the routine proceeds to step 208.

However, night and day cannot be determined from the exposure time S73 obtained when the forced exposure end time T = TS is set. This is because the exposure is forcibly terminated after the time T = TS elapses from the exposure start time regardless of the exposure level S72 of the monitor PD 75 as described above.
This is because the brightness of the object to be measured cannot be determined from the exposure time.

Therefore, whether the result of the day / night determination of the previous data is daytime (201, branch N), or the result of the day / night determination of the previous data is night (201, branch Y) and the forced exposure end time T = TL Only if (206, branch Y),
In the above-described step 202, day / night determination can be performed by comparing the exposure time S73 with the predetermined determination time Th.

If the current determination result is noon (205),
In step 208, a long forced exposure end time T = TL is always set so as to obtain a long exposure time in which the distance of a low-luminance object can be measured. If the result of the current exposure time determination is nighttime (203), in step 204, the forcible exposure end time T is short enough to be a sufficiently short exposure time for measuring the distance of the car light.
= Set TS.

However, if the result of the previous determination is nighttime (2
01, branch Y), when the forced exposure end time T = TL was not set in the previous data, that is, T =
If TS has been set (206, branch N), this time is also considered to be night time (207), but in step 208, forced exposure is performed so that next time it is possible to judge night time or measure the distance of a low-luminance object. Set the end time T = TL.

With such a setting, in the daytime, the exposure control is performed so that the long forced exposure end time T = TL at which the distance measurement of the low-luminance object can be performed. On the other hand, at night, in order to measure the distance of the light of the car, the exposure control forcibly terminated by the short forced exposure end time T = TS and the process of step 202 can be used to determine the nighttime, Exposure control with a long forced exposure end time T = TL is performed alternately so that the distance to the object can also be measured.

Since the previous data does not exist at the start of the first exposure processing, the result of the day / night determination is set as the previous data, the daytime and the forced exposure end time T = TL are set as the initial state, and FIG. Proceed with the flow.
By such processing, in nighttime inter-vehicle distance measurement,
Exposure is forcibly terminated by a sufficiently short forced exposure end time T = TS, and the image signal S62 is amplified by the AGC amplifier 68 at a low magnification.

FIG. 4 is a diagram corresponding to FIG. 14 in the case where the distance between vehicles is measured from an image of a vehicle light at night using the present invention. That is, in the present invention, the difference between the image data of the two optical sensor arrays 63 and 64 as shown in FIG. 14C in the conventional technique is reduced, and the difference as shown in FIG. Light image data 63L and 64R are obtained. Therefore, the image data 63L and 64R are likely to coincide with each other, and the error of the detected shift amount becomes small, that is, the measurement error of the distance becomes small.

Also in the first invention, as shown in FIG. 5, a plurality of optical sensor arrays 64 are arranged so that their lines are parallel to each other, and a line selection switch 74 is operated by a line selection signal from the control circuit unit 80. Switch by S68,
By selecting an arbitrary one of the optical sensor arrays from the plurality of optical sensor array lines, the exposure control of each optical sensor array is independently performed, the field of view of the distance measurement is enlarged, and the optimal optical sensor array is selected. By performing accurate exposure control, it is possible to perform stable inter-vehicle distance measurement with a small measurement error. (Embodiment 2) Next, an embodiment of the second invention will be described with reference to FIGS.

FIG. 6 is a block diagram of a headlight and taillight lighting control circuit according to an embodiment of the second invention.
3, the day / night determination result S74 determined by the day / night determination unit 83 in the process of FIG. 3 or the day / night determination unit 83 determined in the process of FIG. 8 (described later) different from FIG. The determination results S74 of day, twilight, and night are sent to the control circuit unit 80, and the control circuit unit 80 sends signals for turning on and off the headlight 85 and the tail light 86 to S77 based on the determination results. , S7
8 is supplied to one input terminal of the OR circuits 89 and 90.

That is, the headlight ON / OFF signal S77
Is ON or OFF by the driver on the input side of the OR circuit 89.
The tail light ON / OFF signal S78 as an output of the control circuit unit 80 is also connected to the input side of the OR circuit 90.
It is connected together with the output of a tail light switch 92 that can be turned on and off by the driver.

Both the input terminal of the OR circuit 89 to which the switch 91 is connected and the input terminal of the OR circuit 90 to which the switch 92 is connected are normally pulled down via a resistor to the L level, and the switches 91 and 92 are turned on. As a result, each is energized to the H level by the positive voltage V.

The outputs of the OR circuits 89 and 90 are respectively connected to a headlight relay 87 as a relay switch.
And the excitation coil of the taillight relay 88 is energized, and the contacts of the relays 87 and 88 close the power supply of the headlight 85 and the taillight 86, respectively.
Therefore, by manually turning on and off the switches 91 and 92, the headlight 85 and the taillight 86 can be turned on and off, respectively.

The headlight ON / OFF signal S77 and the taillight ON / OFF signal S78 from the control circuit 80 allow the headlight 85 and the tail from the control circuit 80 even when the switches 91 and 92 are OFF. The ON / OFF control of the light 86 becomes possible.

The day / night / night judgment result S 74 by the day / night judgment section 83, the headlight ON / OFF signal S 77 which is an output signal of the control circuit section 80, and the tail light ON / O
FIG. 7 shows the relationship between the value (binary level) of the FF signal S78 and ON / OFF of the headlight and taillight.
Shown in

That is, if the result of the determination by the day / night determining unit 83 is day, the signals S77 and S78 are both set to L level (ground voltage), and both the headlight 85 and the taillight 86 are turned off. If the result of the determination is dusk, the signal S77 is set at the L level, the signal S78 is set at the H level (plus voltage), the headlight 85 is turned off, and the taillight 86 is turned on. If the determination result is night, both signals S77 and S78 are at H level (plus voltage).
, And both the headlight 85 and the taillight 86 are turned on.

FIG. 8 shows an algorithm for judging day, night and dusk by the day / night judging section 83 for lighting control of headlights and tail lights. Note that 301 to 310 are step numbers in the flowchart of FIG.

The day / night / dusk determination algorithm in FIG. 8 is basically the same as the day / night determination algorithm in FIG. When the exposure time S73 measured by the exposure time measurement timer 84 and transmitted from the control circuit unit 80 is longer than a predetermined determination time (referred to as night determination time) Tn (302, branch Y), it is determined that the night is attained (303). ).

Further, a shorter judgment time Tg is set separately from the night judgment time Tn, and the measured exposure time S73 is shorter than the night judgment time Tn (3
02, branch N), and if it is longer than the twilight determination time Tg (304, branch Y), it is determined to be twilight (305).
Further, when the measured exposure time S73 is shorter than the twilight determination time Tg (304, branch N), it is determined that the day is (30).
6).

Based on the determination result S74, the control circuit unit 80 sets the headlight ON / O as described with reference to FIGS.
FF signal S77, tail light ON / OFF signal S78
Are set and output (309, 310). This allows the driver to switch the headlights and taillights 91,
The headlight and taillight can be automatically turned on and off by the control circuit section 80 without operating the 92.

[0086]

According to the first aspect of the present invention, the exposure of the optical sensor array is started and the exposure is completed based on the monitoring of the exposure level of the monitor photodiode which is arranged in parallel with the optical sensor array and starts exposure simultaneously with the optical sensor array. Day and night are determined from the length of the exposure time up to and if the result of the determination is day, a time TL long enough to enable ranging of a low-luminance object is set as the forced exposure end time T, The magnification of the AGC amplifier is set higher than at night so that image data of sufficient contrast can be obtained even with a low-contrast distance measurement object with brightness. In addition, a short time TS is set as the forced exposure end time T, and the magnification of the AGC amplifier is set to a low magnification. If the forced exposure end time T elapses before the exposure of the optical sensor array is terminated based on the monitoring of the exposure level of the light, the exposure of the optical sensor array is forcibly terminated, and the AGC amplifier set as described above. Based on the magnification, the distance to the vehicle is detected from the image data obtained by amplifying the image signal from the optical sensor array, so in the daytime, the exposure time is extended and the amplification magnification of the image signal is increased. Because it can be large, even with a low-brightness, low-contrast object to be measured, sufficient contrast image data can be obtained and stable distance measurement can be performed.At night, the exposure time is short, and the amplification ratio of the image signal is low. Therefore, even if there is an assembly error in the optical sensor array and there is a variation in the amplification factor in the AGC amplifier, the difference between the image data of the left and right optical sensor arrays with respect to the vehicle light is obtained. Can be reduced, it is possible to perform distance measurement of the vehicle lights in small errors.

Further, it is possible to provide an inexpensive inter-vehicle distance measuring apparatus because it is not necessary to assemble the optical sensor array with high accuracy, correct the variation of the amplification factor of the AGC amplifier, and select the AGC amplifier with little variation. .

Further, the plurality of rows of photosensor arrays are switched and selected one by one via a changeover switch so that the exposure control of each photosensor array can be performed independently, so that the optimum exposure control in each photosensor array can be performed. It is possible to perform stable inter-vehicle distance measurement with a small measurement error even when there are a plurality of rows of optical sensor arrays.

According to the second invention, night and day, and further, night, dusk and day are determined from the length of exposure time obtained based on monitoring of the exposure level of the monitor photodiode.
If the result of this determination is night, a signal for turning on both the headlight and taillight is used. If it is dusk, a signal for turning off the headlight and the taillight is turned on. If it is daytime, both the headlight and taillight are turned off. The system automatically generates a signal to turn on and off the headlights and taillights of the vehicle. This saves the driver from troublesome light switch operations, especially turning on the lights when entering and exiting the tunnel during the day. , And forgetting to turn off the light can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main circuit relating to an optical sensor array according to an embodiment of the first invention;

FIG. 2 is a flowchart showing a procedure of an exposure process in FIG. 1;

FIG. 3 is a flowchart of a day / night determination algorithm by a day / night determination unit in FIG. 2;

FIG. 4 is a diagram showing an example of a nighttime inter-vehicle distance measurement result based on the first invention;

FIG. 5 is a configuration diagram of an optical sensor array of a plurality of rows as an embodiment of the first invention.

FIG. 6 is a configuration diagram of a headlight and taillight lighting control circuit as one embodiment of the second invention;

7 is a diagram showing the relationship between the determination results of day, night, and twilight in the circuit of FIG. 6 and the ON / OFF control states of headlights and taillights.

8 is a flowchart of an algorithm for determining day, night, and dusk in the circuit of FIG. 6;

FIG. 9 is a diagram showing a configuration example of an inter-vehicle distance measuring device.

FIG. 10 is an explanatory diagram showing the principle of distance calculation in FIG. 9;

11 is an explanatory diagram of the operation of the distance detection circuit in FIG.

FIG. 12 is an explanatory diagram of a distance measurement range.

FIG. 13 is a configuration diagram of a conventional circuit corresponding to FIG. 1;

FIG. 14 is a diagram showing a problem of a conventional technique.

[Explanation of symbols]

 30A, 40A Image signal 53 Computing means 61, 62 Imaging lens 63 Optical sensor array 63L Image data of optical sensor array 63 Optical sensor array 64R Image data of optical sensor array 64 66 Distance detection circuit 67, 68 AGC amplifier 69, 70 A / D converter 71 Storage device 74 Line selection switch 75 Monitor PD 76 Amplifier 77 Comparator 78 Exposure control unit 79 Monitor PD switching SW 80 Control circuit unit 81L View of optical sensor array 63 81R View of optical sensor array 64 83 Day / night determination Section 84 Exposure time measurement timer 85 Headlight 86 Taillight 87 Headlight relay 88 Taillight relay 89 OR circuit for headlight relay input 90 OR circuit for taillight relay input 91 Headlight switch 92 Taillight switch S 1, S62 Image signal S65 Exposure end signal S67 Gain selection signal S68 Line selection signal S69 Monitor PD range selection signal S70 Exposure start / forced end signal S71 Target exposure level S72 Exposure level S73 Exposure time S74 Day / night judgment result and forced exposure end time S75 Timer start / stop signal S76 Exposure time S77 Headlight ON / OFF signal S78 Tail light ON / OFF signal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA06 BB15 BB29 CC11 DD03 DD09 EE04 EE05 FF01 FF04 FF09 FF70 JJ01 JJ02 JJ03 JJ05 JJ18 JJ22 JJ25 JJ26 LL04 NN12 NN13 NN16 QQ03 Q28 BAQ12 Q06 BAQ06 QQ23Q06 CA05 DA04 DA28 FA03 FA07 FA12 FA21 FA29 FA45 FA50 GA10 5H180 AA01 CC01 CC09 LL01 LL04 LL08

Claims (11)

[Claims] 1. A pair of light receivers each comprising one or more rows of optical sensor arrays are formed on an imaging plane of a pair of imaging lenses whose optical axes are parallel to each other and form an image on the same plane. Corresponding to the lens, the rows of the optical sensor array to be paired are arranged so that they are on the same straight line, respectively, and from the displacement of the object image formed on the pair of optical sensor arrays, the object A plurality of monitor photodiodes arranged in parallel with each optical sensor array, a selected optical sensor array, and a selected monitor arranged in parallel with the optical sensor array. Exposure control means for simultaneously starting exposure of the photosensor array and terminating exposure of the optical sensor array when the exposure level of the monitor photodiode reaches a preset target exposure level. Day and night determining means for determining day or night from the exposure time from the start to end of exposure of the optical sensor array based on the control of the exposure control means; and setting a forced exposure end time separately for the determined day and night. And a forced exposure stop means for forcibly terminating the exposure of the optical sensor array when the forced exposure end time has elapsed before the exposure is terminated by the exposure control means after the exposure of the optical sensor array is started. An inter-vehicle distance measuring device comprising: 2. The inter-vehicle distance measuring apparatus according to claim 1, further comprising: means for setting a gain of an automatic gain control amplifier for amplifying an image signal output from the optical sensor array according to the set forced exposure end time. An inter-vehicle distance measuring device, comprising: 3. A pair of optical receivers each comprising one or a plurality of rows of optical sensor arrays are formed on an imaging plane of a pair of imaging lenses whose optical axes are parallel to each other and form an image on the same plane. Corresponding to the lens, the rows of the optical sensor array to be paired are arranged so that they are on the same straight line, respectively, and from the displacement of the object image formed on the pair of optical sensor arrays, the object An optical sensor array, one or more monitor photodiodes arranged in parallel with each optical sensor array, a selected optical sensor array, and a selected monitor arranged in parallel with the optical sensor array. Exposure control means for simultaneously starting exposure with the photodiode for exposure and terminating exposure of the optical sensor array when the exposure level of the monitor photodiode reaches a preset target exposure level. A day and night determining means for determining day and night from an exposure time from the start to the end of exposure of the optical sensor array based on the control of the exposure control means; And a light control means for controlling ON and OFF of a headlight and a taillight. 4. The inter-vehicle distance measuring device according to claim 1, wherein the day / night determining means is night when the length of the measured exposure time is longer than a predetermined determining time, and night when the measured exposure time is short. An inter-vehicle distance measuring device, which determines daytime. 5. The inter-vehicle distance measuring device according to claim 1, wherein the means for setting the forced exposure end time comprises: A time short enough to be able to measure the distance of the light is set as the forced exposure end time, and when the result of the determination by the day / night determining means is day, the distance is set so that the distance of the low-luminance object can be measured. An inter-vehicle distance measuring apparatus, wherein a time longer than a short time is set as a forced exposure end time. 6. The inter-vehicle distance measuring apparatus according to claim 2, wherein the gain setting means sets the gain to a low magnification when the result of the day / night determination means is night. And when the determination result of the day / night determining means is day, the gain is set to be at least higher than the low magnification so that the distance of the object having low luminance and low contrast can be measured. measuring device. 7. The inter-vehicle distance measuring apparatus according to claim 3, wherein the day / night determining means further determines dusk from the exposure time, and the light control means determines whether the day, dusk or night is determined. ON / OFF of headlight and taillight according to
An inter-vehicle distance measuring apparatus characterized in that the distance is controlled. 8. The inter-vehicle distance measuring apparatus according to claim 7, wherein the day / night determining means determines that the night is a night when the length of the measured exposure time is longer than a predetermined night determination time, and determines the measured exposure time. If the length of time is shorter than the night time determination time, and longer than a predetermined twilight determination time shorter than the night time determination time, it is determined to be twilight, and if the measured exposure time is shorter than the twilight determination time, it is daytime. An inter-vehicle distance measuring device characterized by determining. 9. The inter-vehicle distance measuring apparatus according to claim 3, wherein the light control means switches the headlight and the tail light together when the result of the day / night determination means is night. A signal for turning on the headlights is turned off when the result of the day / night determination means is dusk, and a signal for turning on the taillights is turned off. When the result of the day / night determination means is daytime, both the headlight and the taillight are turned off. An inter-vehicle distance measuring device, which outputs signals to be driven. 10. The inter-vehicle distance measuring apparatus according to claim 9, wherein the headlight is operated under an OR condition of a signal for turning on the headlight of a manually operated switch and a signal for turning on the headlight of the light control means. The inter-vehicle distance measurement is characterized in that the tail light is turned on under an OR condition of a signal for turning on the tail light of a manually operated switch and a signal for turning on the tail light of the light control means. apparatus. 11. The inter-vehicle distance measuring device according to claim 1, wherein the selection of the optical sensor array and the monitoring photodiode is performed via a changeover switch, and every time the selection is made, the same as the above is performed. An inter-vehicle distance measuring device capable of performing exposure.