JP2006197015A - Night vision imaging apparatus for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive night vision imaging apparatus for vehicle by employing lenses the F value of which indicating the lightness of the lenses is increased so as to make the diameter of the lens small/decrease the number of the lenses thereby reducing the manufacturing cost. <P>SOLUTION: In the night vision imaging apparatus for imaging the outside of the vehicle includes: an optical mechanism comprising a combination of a plurality of the lenses 11, 12; an imaging device 13 for receiving a far infrared ray passing through the optical mechanism to produce image data; and a signal processing section 14 for correcting the image data produced by the imaging device 13 into output data of a form whereby the data can externally be transmitted, a plurality of the lenses 11, 12 adopt the F value of 1.4 or over for indicating the lightness of a plurality of the lenses 11, 12. The type of material of a plurality of the lenses 11, 12 is zinc sulfide and produced by sintering. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a night vision for a vehicle that reduces the manufacturing cost by setting the F value of a plurality of lenses made of zinc sulfide (ZnS), which is easy to manufacture and inexpensive, to a high value and reducing the diameter and the number of the lenses. The present invention relates to an imaging apparatus.

  An ambient night vision system in which a far-infrared camera equipped with a bolometer or a pyroelectric image sensor is mounted on a vehicle such as an automobile, and recognizes the presence of a child, a bicycle, etc. existing in front of the vehicle and alerts the driver. Many have been developed.

For example, in Patent Document 1, an imaging unit mounted on a vehicle uses an imaging unit that acquires a far-infrared image by far-infrared rays and a reflector that reflects the far-infrared rays. An image pickup apparatus that can pick up image data that can be detected and can set an image pickup region of an image pickup unit in a required direction is disclosed. A night vision system in which such an imaging device for night vision is mounted on the front of the vehicle and projects a night image on a head-up display has also entered a practical stage.
JP 2004-266767 A

  However, the above-described conventional night vision imaging apparatus using far-infrared rays often uses a bright lens for the lens system including the objective lens, and the lens has a large diameter and the number of lenses increases. In the case of using an expensive material such as (germanium), there is a problem that an imaging device for night vision becomes expensive and difficult to install in a vehicle at a low cost.

  The present invention has been made in view of such circumstances. By increasing the F value indicating the brightness of the lens, the diameter of the lens can be reduced and the number of lenses can be reduced, thereby reducing the manufacturing cost. An object of the present invention is to provide an inexpensive vehicle night vision imaging apparatus.

  To achieve the above object, a night vision imaging apparatus for a vehicle according to a first aspect of the present invention is an imaging mechanism that generates an image data by receiving far-infrared light that has passed through the optical mechanism combined with a plurality of lenses. In a vehicle night vision imaging apparatus for imaging the exterior of a vehicle, comprising: an element; and means for performing correction processing for correcting the image data generated by the imaging element to output data in a format that can be transmitted to the outside. The F value indicating the brightness of the plurality of lenses is 1.4 or more.

  The night-vision imaging device for a vehicle according to a second aspect of the invention is characterized in that, in the first aspect, the material of the plurality of lenses is zinc sulfide and is produced by sintering.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the vehicular night vision imaging apparatus includes an optical element that corrects chromatic aberration on an optical axis of the plurality of lenses.

  In the first invention, an optical mechanism combining a plurality of lenses, an image sensor that receives far-infrared light that has passed through the optical mechanism and generates image data, and image data generated by the image sensor is sent to the outside. In a vehicle night vision imaging apparatus for imaging the outside of a vehicle, the F value of a plurality of lenses is set to a value of 1.4 or more. It is. Accordingly, since the F value of the lens mounted on the conventional night vision imaging apparatus is 1.0 to 1.2, the aperture of the lens can be made smaller than that of the conventional imaging apparatus, and the number of lenses can be reduced. Can also be reduced from the conventional imaging apparatus. Therefore, the cost of the lens can be reduced, and an inexpensive night vision imaging apparatus can be provided.

  In the second invention, zinc sulfide is used as the material of the plurality of lenses, and the lenses are generated by sintering. As a result, compared to the case where Ge (germanium), which is expensive and difficult to process, is used for the lens material, the procurement cost of the material is low, and mass production is possible by sintering. Can be further reduced.

  In the third aspect of the invention, by providing the optical element, the chromatic aberration of the light that is condensed by the lens and guided to the imaging element is corrected. Thereby, the imaging device can capture a high-quality image with corrected chromatic aberration.

  According to the first invention, since the F value of the lens mounted on the conventional night vision imaging device is 1.0 to 1.2, the aperture of the lens can be made smaller than that of the conventional imaging device. The number of lenses can also be reduced as compared with the conventional imaging device. Therefore, the cost of the lens can be reduced, and an inexpensive night vision imaging apparatus can be provided.

  According to the second aspect of the present invention, the cost of procurement of the material is lower than when Ge (germanium), which is expensive and difficult to process, is used as the lens material, and can be mass-produced by sintering. The manufacturing cost of the apparatus can be further reduced.

  According to the third invention, by providing the optical element, the chromatic aberration of the light condensed by the lens and guided to the image sensor is corrected. Thereby, the imaging device can capture a high-quality image with corrected chromatic aberration.

  FIG. 1 is a schematic view showing a state in which a vehicle night vision imaging apparatus according to an embodiment of the present invention is attached. Reference numerals 1 and 2 denote far-infrared video cameras (imaging devices) that image pedestrians, humans, and the like who are subjects of night vision. The video cameras 1 and 2 are arranged in the front grill of the vehicle so as to be separated from each other by an appropriate length in a substantially horizontal direction. Image data captured by the video cameras 1 and 2 is transmitted to the image processing apparatus 3 connected via the in-vehicle LAN cable 6 compliant with IEEE1394.

  In addition to the video cameras 1 and 2, the image processing device 3 is also connected to a display device 4 having an operation unit and an alarm device 5 that issues an audible warning by sound, sound effects, and the like via an in-vehicle LAN cable 6. ing.

  FIG. 2 is a schematic diagram showing the configuration of the video camera 1 of the vehicle night vision imaging apparatus according to the embodiment of the present invention. The objective lens 11 is a standard lens having a focal length of 50 mm formed by molding zinc sulfide (ZnS). The viewing angle of the objective lens 11 is normally 10 to 15 degrees when used for night vision.

  In addition, zinc sulfide lenses can be mass-produced without degrading optical properties by sintering after zinc sulfide is powdered, and manufacturing is not necessary because the cutting process for adjusting the shape is not required. Cost can be reduced.

  The objective lens 11 includes a diffractive optical element 18 for correcting chromatic aberration of light transmitted through the condenser lens 12 at the rear. The diffractive optical element 18 can correct the chromatic aberration of the light condensed by the condenser lens 12 and guided to the imaging element, and can capture a higher quality image with the corrected chromatic aberration.

  The F values of the objective lens 11 and the condenser lens 12 are set in the vicinity of 1.4 to 1.6. That is, the aperture of the lens can be reduced by setting the brightness of the lens to less than half of the set value in a standard night vision imaging apparatus. Also, the number of lenses can be reduced by reducing the brightness of the lenses, and the manufacturing cost of the lenses can be reduced as a whole.

  FIG. 3 is a diagram showing the results when the relationship between the frequency of transmitted light and the contrast is experimentally obtained using two lenses having a viewing angle of 15 degrees with an F value set to 1.4. In FIG. 3, the relationship between the frequency and the contrast is obtained for each frequency resolution, but there is no inflection point at which the contrast rapidly deteriorates depending on the frequency regardless of the frequency resolution. Therefore, even if the number of lenses is reduced by setting the F value high, the deterioration of contrast is sufficiently suppressed, and it should be used for the far-infrared video cameras (imaging devices) 1 and 2. Can be determined to be possible.

  The imaging element 13 is a bolometer, a thermopile, an SOI diode, or the like that converts light collected by the objective lens 11 and the condenser lens 12, particularly infrared light having a wavelength of 8 to 12 μm, into an analog imaging signal for each pixel. It is a non-cooling thermal imaging device, and sequentially outputs an imaging signal converted into an analog signal for each pixel to the signal processing unit 14 via the internal bus 17.

  The signal processing unit 14 is an LSI substrate, converts an analog signal received from the image sensor 13 into a digital signal of luminance (Y), removes various distortions generated in the optical system, and removes low-frequency noise. Processing, correction processing for correcting the gamma characteristic, and the like are performed, and the image data is stored in the image memory 15.

  The communication interface unit 16 is an LSI substrate, and transmits and receives data to and from the image processing apparatus 3 via the in-vehicle LAN cable 6. The communication interface unit 16 sends the image data stored in the image memory 15 to the image processing device 3 in accordance with a command sent from the image processing device 3 and the transfer rate according to the resolution of the images taken by the video cameras 1 and 2. Conversion, generation of packet data for sending image data, and the like are performed.

  FIG. 4 is a block diagram showing a configuration of the image processing apparatus 3 of the vehicle night vision imaging apparatus according to the embodiment of the present invention. The communication interface unit 31 transmits commands to the video cameras 1 and 2 and receives image data from the video cameras 1 and 2. The communication interface unit 31 stores the image data received from the video cameras 1 and 2 in the image memory 32 in synchronization with each frame.

  The communication interface unit 31 transmits image data to the display device 4 such as a liquid crystal display, and transmits an output signal such as a synthesized sound to the alarm device 5 such as a buzzer or a speaker.

  The image memory 32 is an SRAM, a flash memory, or the like, and stores image data received from the video cameras 1 and 2 via the communication interface unit 31.

  The image processing unit 33 is an LSI substrate, reads image data stored in the image memory 32 in units of frames, and based on the read image data, the presence of a person, the presence of a vehicle such as a motorcycle, pattern matching, etc. To determine. When the image processing unit 33 determines that there is a portion corresponding to a vehicle such as a person or a motorcycle in the image data, the image processing unit 33 calculates a distance to a portion corresponding to the vehicle such as a person or a motorcycle, When it is determined that there is a risk of collision with the vehicle based on the calculated distance, a warning message is displayed or a warning sound is output.

  Detailed processing in the image processing unit 33 will be described below. FIG. 5 is a flowchart showing a processing procedure of the image processing unit 33 of the image processing device 3 of the night vision imaging device for a vehicle according to the embodiment of the present invention. The image processing unit 33 acquires image data captured by the video cameras 1 and 2 via the communication interface unit 31, and stores the acquired image data in the image memory 32 (step S501). The image processing unit 33 reads the image data stored in the image memory 32 (step S502), and performs matching processing on the read image data with a standard pattern template corresponding to a human being, a two-wheeled vehicle, or the like that is a characteristic part. By doing so, the correlation value R is calculated (step S503).

  The image processing unit 33 determines whether there is a region where the calculated correlation value R is greater than the predetermined value (step S504), and the image processing unit 33 determines that there is a region where the correlation value R is greater than the predetermined value. If it is determined (step S504: YES), the image processing unit 33 determines that there is a portion corresponding to a person, a two-wheeled vehicle, or the like in the image data, and calculates a distance to a portion corresponding to the person, the two-wheeled vehicle, or the like (step S505). ).

  The calculation of the correlation value R is performed according to (Equation 1).

  In (Equation 1), N is the total number of pixels in the image area to be matched, k is an integer of 0 ≦ k ≦ (N−1), and Fk is a standard template indicating the temperature distribution of the object to be detected. Gk indicates the pixel value of the kth pixel, and Gk indicates the pixel value of the kth pixel in the image region to be matched.

  Note that the method for determining whether or not a person, a vehicle, or the like exists in the read image data matches the standard template indicating the temperature distribution unique to the above-described detection target person, the vehicle, or the like with the image region. It is not limited to the use of the correlation value by itself, but it is determined by combining the size, aspect ratio, average pixel value, variance, etc. of the area recognized as human, vehicle, etc. with the correlation value It may be.

  The image processing unit 33 determines whether or not the calculated distance is shorter than a predetermined value (step S506), and when the image processing unit 33 determines that the calculated distance is shorter than the predetermined value (step S506: YES), It is determined that there is a high risk of collision, and a warning message is displayed or a warning sound is output via the communication interface unit 31 (step S507).

  Moreover, the information regarding the alarm transmitted to the display device 4 and the alarm device 5 is, for example, image data in which the area recognized as the vehicle is highlighted for the display device 4. Further, for the alarm device 5, there are a signal for instructing the buzzer to start ringing, a synthesized voice signal to be reproduced, and the like. The information regarding the alarm is not particularly limited to these.

  As described above, according to the present embodiment, a value larger than 1.0 which is the maximum value of the F value of a lens mounted on a conventional night vision imaging apparatus, for example, an F value of 1.4 to 1.6 is set. By setting it in the vicinity, the aperture of the lens can be made smaller than that of the conventional imaging device, and the number of lenses can also be reduced as compared with the conventional imaging device. Therefore, the cost of the lens can be reduced, and an inexpensive night vision imaging apparatus can be provided.

  Also, compared to using Ge (germanium), which is expensive and difficult to process, as a lens material, zinc sulfide (ZnS) is inexpensive and can be mass-produced by sintering. The manufacturing cost of the apparatus can be further reduced.

It is a schematic diagram which shows the state which attached the night vision imaging device for vehicles which concerns on embodiment of this invention. It is a schematic diagram which shows the structure of the video camera 1 of the night vision imaging device for vehicles which concerns on embodiment of this invention. It is a figure which shows the result at the time of calculating | requiring experimentally the relationship between the frequency of transmitted light, and contrast using two lenses with a viewing angle of 15 degree | times which set F value to 1.4. It is a block diagram which shows the structure of the image processing apparatus 3 of the night vision imaging device for vehicles which concerns on embodiment of this invention. It is a flowchart which shows the process sequence of the image process part 33 of the image processing apparatus 3 of the night vision imaging device for vehicles which concerns on embodiment of this invention.

Explanation of symbols

1, 2 Video camera (imaging device)
DESCRIPTION OF SYMBOLS 3 Image processing apparatus 4 Display apparatus 5 Alarm apparatus 11 Objective lens 12 Condensing lens 13 Imaging element 14 Signal processing part 18 Diffractive optical element 31 Communication interface part 32 Image memory 33 Image processing part

Claims (3)

An optical mechanism combining a plurality of lenses;
An image sensor that receives far-infrared light that has passed through the optical mechanism and generates image data;
In a vehicle night vision imaging apparatus for imaging the exterior of a vehicle, comprising: means for performing correction processing for correcting image data generated by the imaging element into output data in a format that can be transmitted to the outside.
A night vision imaging apparatus for a vehicle, wherein an F value indicating brightness of the plurality of lenses is 1.4 or more.   The night vision imaging device for a vehicle according to claim 1, wherein a material of the plurality of lenses is zinc sulfide and is generated by sintering.   The vehicle night vision imaging apparatus according to claim 1, further comprising an optical element that corrects chromatic aberration on an optical axis of the plurality of lenses.

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