JPH0681311B2 - Vehicle visibility enhancement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention, when applied to a vehicle traveling at night,
It is possible to secure a good visual field in front of the vehicle, to prevent the driver of an oncoming vehicle from being dazzled by the headlight, and to always obtain a good distant view regardless of the presence of an oncoming vehicle headlight. The present invention relates to a vehicle visibility improving device.

<< Prior art and its problems >> In a vehicle running at night, it is possible to increase the intensity of headlight light in order to improve the visibility in front of the vehicle. May dazzle people.

On the other hand, as a vehicle dazzling prevention device, for example, Japanese Patent Laid-Open No. 52-
As disclosed in Japanese Patent No. 101526, a method of blocking headlight light of an oncoming vehicle by a polarizing plate, or JP-A-49-7283
There is known a method in which a variable transmittance filter plate using a liquid crystal or the like is provided on the front surface of a driver as disclosed in Japanese Patent No. 0, and the headlight light of an oncoming vehicle is blocked by this filter plate.
In the former method, the effect is weak unless similar polarizing plates are attached to not only the own vehicle but also the oncoming vehicle.
In the latter case, when the light transmittance of the filter plate is reduced to block the headlight light of the oncoming vehicle, the field of view in front of the vehicle illuminated by the headlight light of the own vehicle is also darkened at the same time. There is a possibility that a driver, such as a pedestrian standing near a vehicle, may misunderstand an object that should be visually recognized by the driver.

<Object of the Invention> When the object of the present invention is applied to a vehicle running at night, for example, the brightness of the headlight light perceived by the drivers of the own vehicle and the oncoming vehicle is not increased, and the vehicle front long distance is increased. An object of the present invention is to provide a vehicle visibility improving device capable of reliably improving the visibility of the vehicle.

<< Structure of the Invention >> In order to achieve the above-mentioned object, according to the present invention, the start and stop of irradiation of a light beam with a predetermined light amount toward a predetermined region in front of a vehicle is seen by a human eye as a constant light amount. A light projecting unit that repeats in a cycle, an image capturing unit that photoelectrically captures the predetermined area and outputs a shadow image signal, a light amount detecting unit that detects the light amount of a light beam incident on the image capturing unit, and an image capturing unit. A period of being interposed in the incident path of the light beam, driven to the transmission state in synchronization with the start of irradiation of the light beam by the light projecting means, and driven to the transmission state as the light amount detected by the light amount detecting means increases. It is characterized in that it comprises a shutter means for shortening the time and an image display means for displaying an image by the video signal to a vehicle occupant.

<< Description of Examples >> First, the principle of the present invention will be described. When human visual characteristics are examined, as shown in FIG. 1, when light is blinked (ON, OFF) at a slow frequency, humans see flickering. However, when the ON / OFF frequency is increased, the flicker finally disappears and the light becomes visible as a constant light. Further, the sense of brightness at this time is as shown by the broken line in FIG.
It becomes equal to the sense of brightness that is felt when viewing stationary light equal to the average value I ′ of the actual light intensity I. This is called Talbot's law.

That is, even if strong light I (e.g., equivalent to a headlight) is emitted, if this light is turned on and off (so that flicker is not felt), light I'weaker than I will be constant to human eyes. I only feel like I'm being sent to.

Further, since the light intensity I'sensed by the human eye shown by the broken line in FIG. 1 is considered to be the average value of I, that is, the integrated value per unit time, the shorter the time the light is turned ON, the more I It is expected that it can be increased.

In addition, the limit frequency at which flicker is not felt is CFF (Cri
It is known that this CFF value is proportional to the logarithm of the brightness of the light source. This is Fe
Called rry-Porter's law.

As explained above, the light is turned on and off at a frequency higher than CFF.
By performing F, it is possible to emit light that does not dazzle oncoming vehicles.

However, although this light has an advantage that it is difficult to dazzle the other party, it also becomes a weak light for myself, and it is not good for improving night visibility of a dark object (for example, a pedestrian) when viewed directly with the naked eye. Is enough.

In the present invention, in order to obtain the light I'of FIG. 1, the light whose ON time is shortened and I is increased is used, and a method of instantaneously irradiating this light is used. Light is received by the image sensor and photomultiplier tube, the received light (image) is amplified,
It aims at a system that aims to improve the visibility at night by displaying it on a display.

In addition, when this system is configured using a solid-state image sensor such as a CCD image sensor, when too strong light is incident from an oncoming vehicle, a phenomenon called blooming occurs,
A white area may appear on the screen of the display, resulting in an image that is difficult for humans to see. Blooming is a phenomenon in which the number of carriers generated in a pixel of a CCD image sensor (generated by receiving light) becomes too large and the carriers flow into other pixels, which affects other pixels.

Therefore, according to the present invention, first, the on / off timing of the liquid crystal plate is synchronized with the intermittent timing of the light of its own light source, and the solid-state imaging device (for example, CC
It was devised so that light would be incident on D).

Particularly, in the embodiment, the direction and amount of strong light incident from an oncoming vehicle or the like are detected, and the light transmittance is changed for each liquid crystal plate installed corresponding to the incident direction to solve the above problem more effectively. It was done.

Further, in this invention, the CCD image sensor is irradiated with light only when the light of its own light source is irradiated, and the light is blocked during other periods, so that weak light hits the CCD image sensor and causes noise. It is also possible to prevent an increase in components (shot noise).

Next, specific examples will be described.

FIG. 2 is a block diagram showing the electrical construction of the vehicle visibility improving device according to the present invention. In the figure, the timing signal generating circuit 1 is for synchronizing the entire circuit. The high-speed pulse train output from the timing signal generating circuit 1 is amplified by the drive circuit 2 and then the light emitting device according to the present invention is emitted. It is supplied to the device 4. The light projecting device 4 is provided in place of the headlight of the vehicle, and visible light is emitted from the light projecting device 4 toward the front of the vehicle while being interrupted at such a high speed that the human eye can see it as a continuous light beam. .

An example of a specific structure of the light projecting device 4 is shown in FIG.

A light projecting device 4 shown in the figure fixes a light bulb 42 serving as a light source in a predetermined sealed housing 41, and reflects light emitted from the light bulb 42 forward through a parabolic reflector 43. , The motor in front of this reflector 43
Disc-shaped slit plates 46, which are rotationally driven by 44 and are provided with slits 45, are arranged to face each other, and this motor 44 is rotated at high speed by a clock signal CK ₁ output from the drive circuit 6, and further provided on the front surface of the housing 41. A lens 47 is fitted into the opened window so that a light beam emitted forward by the reflector 43 and interrupted at a high speed by the slit plate 46 is focused by the lens 47 and then emitted forward of the vehicle.
Further, the light projecting device 4 is provided in place of the headlight of the vehicle, and by appropriately determining the brightness of the light bulb 42, the number of slits 45, the rotation speed of the motor 44, and the like,
It is set so as to sense an irradiation range and brightness comparable to the conventional headlight light irradiation range and brightness in front of the vehicle.

In this way, the light projecting device 4 emits intermittent visible light that is intermittent at a high speed so that it can be seen by the human eye as a continuous light, and the intensity of this intermittent light during the ON period is set to be considerably strong. However, by increasing the intermittent frequency, there is no fear that the driver of an oncoming vehicle will be dazzled by the Talbot's law.

Next, the intermittent light beam emitted from the light projecting device 4 is reflected by an object in front of the vehicle and then introduced into the image pickup device 3 and the light amount detection device 5, respectively.

The image pickup device 3 uses a solid-state image pickup device such as CCD,
The path of light introduced into the image pickup device 3 is divided into three in the vehicle width direction in this example, and liquid crystal plates 6a to 6c capable of adjusting the amount of transmitted light are interposed in each region.

The liquid crystal plates 6a to 6c are, as shown in FIG. 4, two glass plates 6 each having an independent transparent electrode on each inner surface.
1, 62 are stacked in a sandwich shape with a spacer 63 interposed therebetween, and an internal space formed by the spacer is filled with a field effect liquid crystal.

Then, each of the divided liquid crystal plates 6a to 6c is provided with independent electrode terminals 64a to 64c, and the light transmittance of each liquid crystal plate is controlled by controlling the voltage value applied to the electrode terminals. It can be adjusted arbitrarily.

A specific example of the fixed image sensor is shown in FIG.

As shown in the figure, on the light-receiving surface of the solid-state image sensor (CCD in this example), a light-sensing section composed of a phototransistor, etc.
31 are arranged vertically and horizontally, and one pixel is formed by each sensitive section 31 and each vertical register 32 located on the right side thereof. For example, the number of pixels is 320 horizontal pixels × 244 vertical pixels.
It consists of pixels.

The contents of each vertical register 32 are sequentially shifted upward and transferred to each horizontal register 33, and at the same time, the horizontal register 33
Are sequentially shifted to the right in the figure to obtain the pixel output column OUT.

The shift clock φp transfers charges from the sensitive section to each vertical register 32, and the vertical clocks φV ₁ and φV ₂
Is for sequentially shifting the contents of the vertical register 32 to the upper side of the drawing and transferring it to the horizontal register 33. The horizontal clocks φH ₁ and φH ₂ are used to output the contents of the horizontal register 33 to the outside while sequentially shifting the contents to the right.

Next, the operation of this solid-state image sensor will be described with reference to the time chart of FIG. When the shift clock φp becomes “L”, the vertical register connected to the one that is “H” among the vertical clocks φV ₁ and φV ₂ at that time.
Electric charges are transferred from the corresponding sensitive section 31 to 32.

In this time chart, since the vertical clock φV ₂ is “H” when the shift clock φp first becomes “L”, only the portion indicated by the broken line arrow in FIG. The charge is transferred to.

After that, every time the vertical clock φV ₂ arrives, the contents of the vertical register 32 are transferred to the upper side of the paper, and the horizontal register is sequentially transferred.
Enter within 33.

Horizontal clocks φH ₁ and φH ₂ are input to the horizontal register 33, and these clocks φH ₁ and φH ₂ are vertical clocks φV ₂
(Φ V ₁ ) Number of pixels in the horizontal direction during one clock (in this case,
It is a very fast clock pulse that emits a pulse of 320 pixels or more, and the content of the horizontal register 33 is output from the right end every time this clock pulse is input.

The two systems of horizontal clocks φH ₁ and φH ₂ are for interlacing operation. First, the contents of even-numbered (or odd-numbered) horizontal registers 33 are output,
Next, it is for outputting the contents of the odd-numbered (or even-numbered) horizontal registers 33. As described above, the pixel output indicated by the broken line arrow in FIG. 3 is read out to the outside.

Next, when the shift clock φp becomes “L”, this time φV ₁
Is "H", the pixel output indicated by the solid line arrow in FIG. 3 is read out, and charges are transferred from the sensitive section 31 to the vertical register 32. Subsequent operations are the same as in the case of the broken arrow, and therefore will be omitted.

In this way, when the two shift clocks φp arrive, the signals of all the pixels are output from the right end of the horizontal register 13 in time series, and the pixel output column OUT is obtained. Although there are actually circuits for waveform shaping, noise elimination, etc. in the output terminal section, only the operating principle is described here, and the details of the above circuits are omitted.

On the other hand, as shown in FIG. 7, the light amount detecting device 5 includes lenses 50a to 50c for condensing a part of the light incident on the liquid crystal plate in each of the regions, and lens barrels 51a to 51c for supporting the lenses. Photoelectric devices 52a to 5 such as phototransistors provided on the base
2c and the liquid crystal plate 6 in each area.
The amount of light incident on a, 6b, and 6c can be detected for each region.

Then, the respective light receiving elements 52a to 52c constituting the light amount detection device 5
Are supplied to the transmitted light amount control circuits 7a, 7b, 7c, respectively. In addition, in the example of FIG. 2, since the configuration is the same, only the transmitted light amount control circuit 7a is shown in detail.

The transmitted light amount control circuit 7a includes three comparators 71a to 71c for discriminating the level of the detection output of the light receiving element 52a by comparing with the reference voltages V _{1 to} V ₃ , respectively, and inverters 72, 73 and AND gates 74, 75. Each of the comparators 71a to 71a
A decoder that discriminates the amount of received light into three levels based on the output of c and a one-shot pulse that is driven in synchronization with the clock pulse output from the timing signal generation circuit 1 and that has different pulse widths are output. AND gates 77a, 77b, 77c which are gate-controlled by the respective outputs of the decoders and pass through the outputs of the corresponding mono-multis 76a, 76b, 76c.
And an OR gate 78 that takes the logical sum of the outputs of these AND gates 77a, 77b, and 77c, and a drive circuit that amplifies the output of this OR gate and applies it to the liquid crystal plates 6a, 6b, and 6c in each region. It is composed of a circuit 79.

Therefore, as shown in the time chart of FIG.
Depending on the amount of light detected by 52a, each comparator 71a-71
When the output of c changes, the pulse width of each one-shot pulse output from each AND gate 77a to 77c in the cycle of the intermittent light beam becomes shorter as the detected light amount increases.

As a result, the transmission time of the liquid crystal plate 6a interposed in the optical path entering the image pickup device 3 changes, that is, as the amount of received light increases, the amount of light that passes through the corresponding liquid crystal plate and reaches the image pickup device 3. Will decrease.

The same applies to the operations of the transmitted light amount control circuits 7b and 7c, whereby the amount of transmitted light of the liquid crystal plates 6a to 6c decreases in accordance with the amount of light reaching from each region divided in the vehicle front width direction. For example, even when strong headlight light arrives from an oncoming vehicle, it is possible to prevent the blooming phenomenon from occurring in the solid-state imaging device corresponding to the area.

Next, each pixel output column output from the image pickup device 3 becomes a video signal after being horizontally and vertically synchronized in the video signal generation circuit 8 in synchronization with the clock supplied from the timing signal generation circuit 1. It is supplied to the image display device 9 including a CRT, a liquid crystal display, and the like.

Next, in the image display device 9, after amplifying the video signal, each pixel on the screen is sequentially driven in synchronization with this, so that a distant object in front of the vehicle is displayed on the screen of the image display. It is done. That is, with respect to the object at a short distance and a medium distance in front of the vehicle, the driver is illuminated by the intermittent light beam from the light projecting device 4 with the same brightness as the conventional headlight light,
In contrast to the naked eye, the field of view far from the vehicle can be confirmed via the image displayed on the image display device 9. The image display device 9 may be attached at an appropriate position near the driver's seat in the vehicle.

Next, FIG. 9 shows another example of the transmission amount control circuits 7a to 7c. In this example, the applied voltage supplied to each of the liquid crystal plates 6a to 6c is switched in three stages.

That is, the output from the light receiving element 52a is level-discriminated in three stages by the three comparators 701a to 701c in the same manner as in the above embodiment, and then the outputs of the comparators 701a to 701c are output from the three analog switches 702a to 702c. Is supplied as an ON / OFF control signal.

These analog switches 702a~702c is interposed to the input path from the reference voltage V ₁₁ ~V ₃₃ formed by the resistor divider to the addition circuit 703, the order receiving element
When the output of 52a changes, an analog voltage of three stages is output from the adder circuit 703, and the analog voltage is amplified by the drive circuit 704 and then supplied to the liquid crystal plate 6a constituting the image pickup device. Is.

The outputs of the light receiving elements 52b and 52c are also supplied to similar transmission amount control circuits, and then the supply of the liquid crystal plates 6b and 6c is controlled by the outputs of the transmission amount control circuits.

That is, by varying the applied voltages to the liquid crystal plates 6a to 6c in three stages, the transmittance of each liquid crystal plate can be switched in three stages.

In the above embodiment, the liquid crystal plates 6a to 6c are set in the non-transmissive state during the intermittent light OFF period emitted from the light projecting device 4, and the liquid crystal plates 6a to 6c are turned on during the intermittent light ON period according to the received light amount. Although the transmitted light amount of the plates 6a to 6c is changed, the structure of decreasing the transmitted light amount of the liquid crystal plate according to the received light amount is not particularly adopted, and the intermittent light
Even by adopting the configuration in which the liquid crystal plate is in a transmissive state only during the ON period, noise rays and strong headlight light are introduced into the image sensor 3 in correspondence with the OFF period of the intermittent light to improve the image sharpness. The problem of reduction can be sufficiently prevented.

Next, another specific example of the light projecting device is shown in FIG. In the floodlighting device shown in the figure, the light bulb 410 serving as a light source is covered with a cylindrical reflector 411 having a window 414 on one side thereof, and the reflector 411 is covered with a motor 412 and a speed increasing gear train.
Rotate at high speed through 413, which causes reflector 411
The visible light is emitted to the front of the vehicle while being intermittently interrupted at a high speed only during the period when the window of the front of the vehicle faces the front of the vehicle. According to this example, the intermittent frequency of the intermittent light beam can be increased without significantly increasing the rotation speed of the motor.

Another example of the light projecting device is shown in FIG. The floodlighting device shown in the same figure reflects the light from a light bulb 420 serving as a light source into a parabolic reflector 4
The light is reflected and focused at 21 and emitted forward, and an electromagnetic shutter 422 is further provided in front of the electromagnetic shutter 422. The electromagnetic shutter 422 is interrupted at high speed by a high-speed pulse generated from a timing circuit 423, whereby light from a light source is emitted. It is designed to be emitted intermittently toward the front of the vehicle.

According to this example, a high-speed intermittent light beam can be obtained without using a rotating machine such as a motor.

Another example of the light projecting device is shown in FIG. The floodlighting device shown in the figure is a device in which the headlamp itself for both traveling and the flashing is made to blink at high speed. That is, 430 is a light bulb as a light source, 431 is a parabolic reflector, 432 is a 90-degree reflecting mirror that guides half of the light reflected and focused by the parabolic reflector 431 to the left headlight system, and 433 alternates the remaining light. And 434 and 435 are 90-degree reflection mirrors for introducing the light obtained by the reflector 431 to the entrance end of the passing optical fiber 436 and the traveling 437.

Reference numeral 438 is a front glass of a headlight, and 439 is a headlight reflector, and the emission ends of the optical fibers 436 and 437 are positioned at the focal point of the reflector 439.

A spherical lens 440 or 441 is attached to the output end of each optical fiber 436 or 437.
Are formed so as to diffuse the emitted light.

In the above configuration, by rotating the rotating mirror 433 at high speed, the traveling beam and the passing beam can be alternately emitted to the front of the vehicle at high speed to obtain the intermittent light beam according to the present invention.

According to this method, since the light source is not placed in the headlamp and can be placed in another arbitrary place, the work of replacing the light bulb becomes easy, and only by controlling the rotating mirror,
Intermittent light can be easily obtained.

Although the floodlighting device 4 is attached in place of the headlight in the above-described embodiment, it goes without saying that an auxiliary lamp at the front of the vehicle may be used instead.

Further, in the above-described embodiment, the light is radiated in a broken line, but instead of this, the same effect can be obtained by changing the illuminance of the light in steps (10% illuminance and 100% illuminance).

Further, in the above-mentioned embodiment, the amount of transmitted light of each liquid crystal plate is changed in three steps in a stepwise manner. However, if the output of each light receiving element is simply amplified and then supplied to each liquid crystal plate in proper synchronization,
It goes without saying that the transmittance of each liquid crystal plate can be continuously controlled according to the amount of received light.

<< Effects of the Invention >> As is apparent from the above description of the embodiments, according to the present invention, the visibility of a vehicle far away can be achieved without dazzling the driver of the oncoming vehicle and without impairing the visibility in front of the vehicle. Even if an external ray arrives during the off period of the intermittent light emitted from the light projecting device, the sharpness of the displayed image does not decrease.

Further, according to the present invention, even when strong headlight light or the like arrives from an oncoming vehicle, the solid-state image pickup device such as CCD constituting the image pickup device causes a blooming phenomenon, which causes a so-called blank state on the display screen. Has the effect that no

[Brief description of drawings]

FIG. 1 is a graph for explaining the principle of the present invention, FIG. 2 is a block diagram showing the electrical configuration of the device of the present invention, and FIG. 3 is a diagram showing a specific example of the light projecting device. FIG. 7 is a schematic diagram showing the configuration of the liquid crystal plate, FIG. 5 is a diagram showing the pixel configuration of the solid-state image sensor, FIG. 6 is a waveform diagram showing the signal state of each part of FIG. 5, and FIG. FIG. 8 is a schematic diagram showing the configuration, FIG. 8 is a waveform diagram showing the signal state of each part in FIG. 2, FIG. 9 is a block diagram showing another example of the light amount control circuit, and FIGS. It is a figure which shows the other example of an apparatus. 3 ... Imaging device 4 ... Projection device 5 ... Light amount detection device 6a-6c ... Liquid crystal plate 7a-7c ... Transmitted light amount control circuit 9 ... Image display device

Claims (2)

[Claims] 1. A light projecting means for repeating a start and a stop of irradiation of a light beam with a predetermined light amount toward a predetermined region in front of a vehicle in a cycle in which a constant light amount appears to human eyes, and the predetermined region. An image pickup unit that photoelectrically picks up the image signal and outputs a video signal, a light amount detection unit that detects the light amount of the light beam that enters the image pickup unit, and an incident path of the light beam that enters the image pickup unit, and the light projecting unit. Shutter means that is driven in a transmissive state in synchronization with the start of light irradiation by the means, and shortens the period in which the light amount detected by the light amount detecting means is driven in a transmissive state, and an image based on the video signal. An image display device for displaying the above to a vehicle occupant, and a visual field improving device for a vehicle, comprising: 2. The vehicle visibility improving device according to claim 1, wherein the light projecting means has an irradiation range and an average illuminance that are substantially the same as those of normal headlight light.