JPH0728394B2 - Dimmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a light control device used for a photodetector that captures incident light and converts it into a predetermined signal, and particularly an image provided in an automobile or the like. The present invention relates to a dimming device useful for a recognition device.

[Prior Art] Conventionally, as an image recognition system for an automobile, a preceding vehicle 305, an oncoming vehicle 307, a guardrail 309, etc. are imaged by visible light with a light receiver 303 mounted in front of the vehicle 301 as shown in FIG. There was something that was recognized and recognized as, and used as judgment data such as driving.

[Problems to be Solved by the Invention] However, sufficient light detection is not possible at night or in a tunnel only by receiving external visible light such as sunlight, and it is possible to detect light even in the early morning or evening even in the daytime. In some cases, sunlight is directly incident on the container 303 or reflected light is incident from a mirror surface such as a glass window, so that the light receiving element of the light receiver 303 is saturated and image recognition cannot be performed.

For adjusting the incident light, it is possible to use a liquid crystal type light control device as shown in JP-A-62-255220, but the amount of light itself is insufficient at night, in a tunnel, etc. Don't do it. Further, when the headlight is used as the auxiliary light, the irradiation range is limited and the uniformity is insufficient. For this reason, it is possible to irradiate other auxiliary light to the front side and capture the reflected light, but the headlight of an oncoming vehicle or the like may cause image recognition error.

SUMMARY OF THE INVENTION Therefore, in order to solve the above problems, the present invention has an object to provide a light control device that enables a photodetector to appropriately detect light both day and night, and adopts the following configuration. .

[Means for Solving the Problems] That is, the gist of the present invention is, as illustrated in FIG. 1, used in a photodetector S for capturing incident light and converting it into a predetermined signal. In the dimming device for adjusting the intensity of the solar light sensor M1, a filter M2 provided in the optical path of the incident light and capable of adjusting the transmission amount of light of a predetermined wavelength including at least the wavelength range of the vehicle headlight, and the filter Depending on the adjustment of the amount of transmission by M2, the external irradiation means M3 capable of externally irradiating wavelength light that is hardly affected by the transmission of the filter M2, and when the external light captured by the solar radiation sensor M1 is stronger than a predetermined value, The above-mentioned filter according to the detection result of the photodetector S
Adjusting the transmission amount of M2, when the external light captured by the solar radiation sensor M1 is weaker than a predetermined value, the filter driving means M4 for suppressing the transmission amount low, and the external light captured by the solar radiation sensor M1 is lower than a predetermined value. An irradiation drive unit M5 that drives the external irradiation unit M3 when it is weak, and a light control device.

[Operation] In the daytime, the solar radiation sensor M1 detects light that is stronger than a predetermined value. At this time, the filter driving means M4 controls the filter M2 in accordance with the detection result of the light detecting means S so that the amount of external light incident on the light detecting means S becomes an appropriate amount.

On the other hand, at night or in a tunnel, the solar radiation sensor M1 detects light that is weaker than a predetermined value, or does not detect light at all. At this time, the filter M2 can keep the transmission amount low by the filter driving means M4. Therefore, the light from the headlight of the oncoming vehicle is unlikely to pass through the filter M2 and is hardly detected by the photodetector S. Therefore, the light detection device S is not affected by the headlight of the oncoming vehicle. However, at this time, the irradiation driving means M5 drives the external irradiation means M3 to irradiate the predetermined wavelength light to the outside. The wavelength light emitted by the external irradiating means M3 is light that can be transmitted through the filter M2 without being substantially affected by the transmission amount (transmittance) adjustment of the filter M2. Therefore, although the light from the headlight of the oncoming vehicle is unlikely to pass through the filter M2, the reflected light of the irradiation light from the external irradiation means M3 passes through the filter M2 and is detected by the photodetector S. As a result, the image data can be detected without being affected by the headlight of the oncoming vehicle.

Next, examples of the present invention will be described. The present invention is not limited to these, and includes various embodiments without departing from the scope of the invention.

[Embodiment] FIG. 2 is a system configuration diagram of an embodiment of a light control device of the present invention used in an image recognition device for an automobile.

The CCD 1 which is an image sensor forms an image of each pixel on the surface of the photosensitive portion when external light incident through the beam splitter 3, the convex lens 5, the liquid crystal filter 7 and the polarizing plate 9 arranged in front of the CCD 1 forms an image. It is output after being converted into a video signal representing the light intensity of. The detection signal of the CCD 1 is amplified by the amplifier 11 and output to the terminal 13 to be used for desired control.

Separately, a solar radiation sensor 15 is provided outside the vehicle compartment to detect sunlight directly and indirectly. For example, a photo sensor or the like is provided to detect the brightness of the sky. The filter drive circuit 17 controls the light transmittance of the liquid crystal filter 7 based on the output of the solar radiation sensor 15 and the output of the CCD 1. Further, the irradiation drive circuit 19 controls the near infrared laser light output of the laser diode 21 based on the output of the solar radiation sensor 15.

The filter drive circuit 17, the determination circuit, determines the level of the output value of the solar radiation sensor 15, it is a high level,
That is, when it is judged that it is daytime, the CC amplified by the amplifier 11
The video signal of D1 is calculated by an integrating circuit for an integrated value for one screen, and the light transmittance of the liquid crystal filter 7 is adjusted according to the value. That is, if the integrated value is high, the external light is strong,
The light transmittance of the liquid crystal filter 7 is reduced in order to prevent the saturation of the CCD 1. On the contrary, if the integrated value becomes low, the external light is weak. Therefore, in order to improve the detection accuracy of CCD 1, the liquid crystal filter 7
Increase the light transmittance of. When it is determined that the output of the solar radiation sensor 15 is at a low level, that is, at night (including inside the tunnel), the light transmittance of the liquid crystal filter 7 is set to the minimum (here, the non-transmissive state). That is, this is to cut off external light such as headlights of an oncoming vehicle, which may cause malfunction of the CCD 1.

As the liquid crystal filter 7, for example, a host / guest type liquid crystal filter in which a host liquid crystal contains a dichroic dye as a guest is used. The dichroic dye used here is selected such that it absorbs visible light such as sunlight in the non-transparent state array but does not absorb light in the near infrared region but transmits it. . The change of the transmittance is performed by controlling the voltage applied to the electrodes 7a and 7b of the liquid crystal filter 7 to adjust the arrangement direction of the liquid crystal molecules 25 and the dye molecules 27 in the liquid crystal tank 7c. The host / guest type liquid crystal filter includes a nematic type, a smectic type, and a cholesteric type, and is a nematic type in this embodiment, but of course, another type of liquid crystal filter may be used. -Types other than guests may be used.

The irradiation drive circuit 19, the determination circuit determines the level of the output value of the solar radiation sensor 15, low level, that is, when it is determined that it is night, the switching circuit works to operate the drive circuit of the laser diode 21. As shown in FIG. 3, the laser diode 21 outputs near-infrared laser light toward the beam splitter 3. Beam splitter 3
The laser light reflected forward by the vehicle illuminates the front of the vehicle 301 from the image recognition device 70 through the convex lens 5, the liquid crystal filter 7 and the polarizing plate 9 as shown in FIG. However, since the vibration direction of the laser light is made to coincide with the polarization direction of the polarizing plate 9, it is not dimmed by the polarizing plate 9. Further, as shown in FIG. 6, the liquid crystal filter 7 hardly interferes with the transmission of near infrared light, so that the reflected light of near infrared light reaches the CCD 1 as it is.
However, since the headlight and the like are shielded by the liquid crystal filter 7, accurate image recognition can be performed only by the near infrared light without being confused by the headlight and the like.

Next, FIG. 4 shows an example in which the filter drive circuit 17 and the irradiation drive circuit 19 are integrally configured as an arithmetic control circuit (ECU) 60 as a microcomputer.

The ECU 60 is configured as a logical operation circuit centering on the CPU 60a, ROM 60b, RAM 60c, etc., and the input circuit 6 via the common bus 60d.
It is connected to 0e and the output circuit 60f to perform input / output with the outside.

Next, the control processing of the liquid crystal filter 7 and the laser diode 21 executed by the ECU 60 will be described based on the flowchart shown in FIG. This control is started when the power of the ECU 60 is turned on.

First, when the process is started, various flags, variables, and other values are set to initial values, and various control targets are set to their initial states (step 100). Next, the output of the solar radiation sensor 15 is read. The analog value of the solar radiation sensor 15 is converted into a digital signal by the A / D converter provided in the input circuit 60e, and is taken into the CPU 60a (step 110). It is determined whether or not this digital value is equal to or greater than a predetermined value set in advance, that is, whether or not there is a sufficiently bright daytime outside (step 120), and if a positive determination is made, the output of each pixel of the CCD1 is read. (Step 130). Next, the read values for each pixel are accumulated (integrated) (step
140). Next, it is determined whether or not this cumulative value is equal to or higher than a preset upper limit level (step 150). If a positive determination is made here, it is determined that the external light passing through the liquid crystal filter 7 is strong and the CCD 1 is saturated, so the calculated applied voltage VL is decreased by ΔV (step 160). Also,
When a negative determination is made in step 150, it is determined whether the cumulative value is equal to or lower than a preset lower limit level (step 170). If an affirmative determination is made here, it is determined that the external light passing through the liquid crystal filter 7 is weak and is not suitable for CCD 1 image detection. Therefore, the calculated applied voltage VL is ΔV.
Increment by one (step 180). If negative determinations are made in both step 150 and step 170, the intensity of the transmitted light is determined to be appropriate, and therefore the calculated applied voltage VL does not change.

When the value of the applied voltage VL is determined in this way, the liquid crystal filter 7
The actual applied voltage of is controlled between 0V and the upper limit voltage based on the calculated value (step 190). That is, when the applied voltage is 0 V, the liquid crystal molecules 25 of the liquid crystal filter 7 are arranged parallel to the surfaces of the electrodes 7a and 7b and parallel to the polarization direction of the polarization filter 9 as schematically shown in FIG. . Dye molecule
27 also follows the arrangement of the liquid crystal molecules 25. At this angle, sunlight, headlights, etc., which the dye molecule 27 has passed through the polarizing filter 9, vibrate the dye molecule 27 and are absorbed.
Therefore, sunlight or the like hardly passes through the liquid crystal filter 7 and does not reach the CCD 1.

On the contrary, when the applied voltage is the upper limit voltage, the liquid crystal molecules 25 of the liquid crystal filter 7 have the electrodes 7a and 7b, as schematically shown in FIG.
They are arranged perpendicular to the plane, and the dye molecules 27 also follow the arrangement of the liquid crystal molecules 25. At this angle, sunlight, headlights, etc., through which the dye molecules 27 have passed through the polarizing filter 9 do not vibrate the dye molecules 27 and are not absorbed. Therefore, most of the sunlight or the like passes through the liquid crystal filter 7 and reaches the CCD 1 as it is. The above ΔV changes the applied voltage in a stepwise manner. The lower the VL, the lower the light transmittance of the liquid crystal filter 7, and the higher the VL, the light transmittance of the liquid crystal filter 7 decreases. Raise.

After the process of step 190, the process returns to step 110, and as long as the positive determination is made in step 120, the above process is repeated.

Next, when a negative determination is made in step 120, VL is set to zero (step 200). Next, laser diode 21
Is driven and laser light is emitted from the vehicle 301 as shown in FIG.
It is irradiated forward (step 210). Next, the actual applied voltage of the liquid crystal filter 7 is controlled to 0V (step 19).
0). That is, headlights, streetlights, etc. that have passed through the polarization filter 9 vibrate the dye molecules 27 and are absorbed. Therefore, headlights, streetlights, etc. hardly pass through the liquid crystal filter 7 and do not reach the CCD 1. However, as shown in FIG. 6, the dye molecule 27 causes the electrodes 7a, 7b and the polarizing plate 9
Since the absorption band of the dye when it is arranged parallel to the polarization direction is limited to the visible light region, near infrared light (wavelength 1300 to 15000 nm) is not absorbed. Therefore,
A desired image can be obtained without being confused by headlights, streetlights, and the like.

Thereafter, the above process is repeated as long as a negative determination is made in step 120.

Since the present embodiment is controlled as described above, it is possible to obtain an appropriate image regardless of the intensity of external light in the daytime, and without being confused by headlights, street lights, etc. at night or in a tunnel. A proper image can be obtained.

Further, in a tunnel or the like, the detection is automatically and instantly switched to the near infrared light, so that there is no time lag such as mechanically exchanging the optical filter, and it is possible to continuously obtain appropriate images.

When detecting an image with near-infrared light at night or the like, the focus of the convex lens 5 moves, so the position of the convex lens 5 or the CCD 1 may be moved according to the movement.

Further, the application may be applied not only to automobiles but also to intelligent robots and outdoor or indoor monitoring systems.

In the above embodiment, the CCD1 corresponds to the photodetector S, the laser diode 21 corresponds to the external irradiation means M3, the filter drive circuit 17 and the ECU 60 correspond to the filter drive means M4,
The irradiation drive circuit 19 and the ECU 60 correspond to the irradiation drive means M5.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, image recognition is always properly performed during the daytime without the light receiving elements of the photodetector S being saturated. Further, at night or in the tunnel, the filter M2 almost blocks the light of the oncoming vehicle, and the photodetector S captures only the reflected light of the light emitted from the external irradiation means M3 to the outside, so that the light of the oncoming vehicle is detected. Does not lead to an error in image recognition. In a tunnel or the like, detection is automatically switched to another wavelength light such as near-infrared light, so there is no time lag such as mechanical replacement of the optical filter.

[Brief description of drawings]

FIG. 1 is a basic exemplification diagram of the present invention, FIGS. 2 and 3 are configuration diagrams of an embodiment of the present invention, FIG. 4 is a system configuration diagram using a microcomputer, and FIG. FIG. 6 is a flow chart, FIG. 6 is a graph showing the degree of light absorption (light attenuation) with respect to the wavelength of the liquid crystal filter, FIG. 7 is an explanatory view of the image detection state by irradiation with near infrared light, and FIG. 8 is an explanatory view of the image detection state. Represents M1 …… solar radiation sensor, M2 …… filter M3 …… external irradiation means M4 …… filter driving means, M5 …… irradiation driving means 1 …… CCD, 3 …… beam splitter 5 …… convex lens, 7 …… liquid crystal filter 9 ...... Polarizer, 11 …… Amplifier 15 …… Solar sensor, 17 …… Filter drive circuit 19 …… Irradiation drive circuit, 21 …… Laser diode

Claims (2)

[Claims] 1. A dimming device for use in a photo-detecting device for capturing incident light and converting it into a predetermined signal, for adjusting the intensity of the incident light, comprising a solar sensor and an optical path of the incident light, and at least A filter capable of adjusting the transmission amount of light of a predetermined wavelength including the wavelength range of the vehicle's headlight, and external irradiation capable of irradiating wavelength light that is hardly affected by the transmission of the filter to the outside by adjusting the transmission amount of the filter. When the external light captured by the means and the solar radiation sensor is stronger than a predetermined value, the transmission amount of the filter is adjusted according to the detection result of the photodetector, and the external light captured by the solar radiation sensor is more than a predetermined value. When weak, the filter driving unit that suppresses the transmission amount to a low level, and the irradiation driving unit that drives the external irradiation unit when the external light captured by the solar radiation sensor is weaker than a predetermined value, Dimmer, characterized in that it includes. 2. The light control device according to claim 1, wherein the light detection device is mounted on an automobile and used for image recognition.