JP2008048066A - Far infrared imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a far infrared imaging system capable of acquiring an image holding a sufficient clearness even when the vehicle speed, ambient illuminance, etc. varies. <P>SOLUTION: The system comprises a far infrared imaging apparatus having one or a plurality of condensing lenses, a plurality of imaging elements arranged in a matrix for converting lights collected by the lenses into electric signals, an image processor circuit for forming an image based on the output values of the imaging elements, and a vehicle speed sensor for detecting the speed of a vehicle mounting the far infrared imaging apparatus. The far infrared imaging apparatus comprises a diaphragm mechanism capable of gradually changing the aperture in front of the lenses, and a means for changing the opening degree of the diaphragm mechanism, thereby changing the opening degree of the diaphragm mechanism according to the detection value of the vehicle speed sensor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a far-infrared imaging system capable of adjusting the resolution of a far-infrared imaging device that images the outside.

  In order to ensure the safety of traveling of vehicles such as automobiles, far-infrared imaging devices such as night vision capable of detecting the presence of obstacles such as pedestrians and bicycles at night have been developed. When used in a collision prevention system with a vehicle obstacle, usually two far-infrared imaging devices are set at a predetermined position in front of the vehicle, and the distance to the obstacle detected by stereo vision Is calculated. Then, the presence / absence of a collision is determined based on the calculated distance, vehicle speed, and the like.

  A far-infrared imaging device that captures image data serving as a basis for determination includes a lens, an imaging element, and an image processing circuit. At the time of imaging, external light is condensed through the lens, and the luminance value detected by the imaging device is A / D converted by an image processing circuit and processed as a digital signal.

The far-infrared imaging device includes a diaphragm mechanism in front of the lens, and the diaphragm mechanism is opened and closed by an actuator. By using the aperture mechanism, the resolution is improved in the apertured state, and a farther object can be imaged (see Patent Document 1).
Japanese Patent No. 2753531

  However, the above-described imaging apparatus cannot adjust the aperture degree according to the speed. Therefore, for example, when the speed of the vehicle is increased, sufficient resolution cannot be maintained, and there is a possibility that an obstacle may be missed or misrecognized due to the captured image becoming unclear. There was a point.

  In addition, when the illuminance around the vehicle decreases due to sunset or the like, the amount of light is insufficient by increasing the aperture amount to maintain sufficient resolution, and obstruction detection failure due to the captured image becoming unclear There is a problem that erroneous recognition or the like may occur.

  The present invention has been made in view of such circumstances, and far-infrared imaging capable of acquiring an image with sufficient sharpness even when the speed of the vehicle, ambient illuminance, or the like fluctuates. The purpose is to provide a system.

  In order to achieve the above object, a far-infrared imaging system according to a first aspect of the present invention includes one or a plurality of lenses that collect light, and a plurality of lenses arranged in a matrix that converts light collected by the lenses into electrical signals. A far-infrared imaging device having an image sensor and an image processing circuit that forms an image based on an output value for each imaging device, and a vehicle speed sensor that detects the speed of a vehicle on which the far-infrared imaging device is mounted In the far-infrared imaging system, the far-infrared imaging device includes an aperture mechanism capable of gradually changing opening and closing on the front surface of the lens, and means for changing an opening degree of the aperture mechanism, and the vehicle speed The opening degree of the diaphragm mechanism is changed according to the detection value of the sensor.

  In the first invention, the far-infrared imaging device includes a diaphragm mechanism capable of gradually changing opening and closing on the front surface of the lens, and means for changing the opening degree of the diaphragm mechanism. The opening degree of the throttle mechanism is changed according to the detected vehicle speed. Thereby, for example, when the speed of the vehicle increases, the degree of opening of the aperture mechanism is decreased, that is, the aperture amount is increased, thereby improving the resolution and making the output value at the imaging device clearer. It becomes possible. Further, when the speed of the vehicle decreases, the output value of the image sensor can be made clearer by increasing the degree of opening of the aperture mechanism, that is, by reducing the aperture amount.

  The far-infrared imaging system according to the second invention further comprises an illuminance sensor for detecting illuminance in the first invention, and changes the degree of opening of the aperture mechanism in accordance with the detection value of the illuminance sensor. It is characterized by that.

  In the second invention, the brightness around the vehicle is detected by the illuminance sensor, and the opening degree of the aperture mechanism is changed according to the detected brightness around the vehicle. Thereby, for example, even when the surroundings of the vehicle are dark, it is possible to avoid a shortage of light quantity by increasing the aperture amount so as to maintain sufficient resolution, and the captured image becomes clearer. It becomes possible.

  According to the present invention, the resolution can be changed according to the situation by increasing or decreasing the opening degree of the diaphragm mechanism according to the speed of the vehicle and the brightness of the surroundings of the vehicle, that is, by increasing or decreasing the diaphragm amount, The output value of the image sensor can be made clearer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a far-infrared imaging system according to an embodiment of the present invention. In the present embodiment, a set of far-infrared imaging devices 1 and 1 that capture surrounding images while traveling are mounted in the front grille near the center in front of the vehicle (also possible in a bumper). The far-infrared imaging devices 1 and 1 are imaging devices using infrared light having a wavelength of 7 to 14 micrometers.

  In FIG. 1, far-infrared imaging devices 1 and 1 are juxtaposed in a substantially symmetrical position in the left-right direction within a front grill of a vehicle. Image data captured by the far-infrared imaging devices 1 and 1 is transmitted to an arithmetic device 3 connected via a video cable 7 corresponding to an analog video system such as NTSC or a digital video system.

  The arithmetic device 3 executes various arithmetic processes using the acquired far infrared image data. The arithmetic device 3 is connected to the far infrared imaging devices 1 and 1 and the display device 4 having an operation unit via a cable 8 corresponding to a video system such as NTSC, VGA, DVI, etc. An output device such as an alarm device 5 that emits an audible warning by a sound effect or the like is connected via an in-vehicle LAN cable 6 compliant with CAN.

  The computing device 3 is also connected to the vehicle speed sensor 2 for detecting the speed of the vehicle and the illuminance sensor 9 for detecting the illuminance of the surroundings via an in-vehicle LAN cable 6 compliant with CAN. Illuminance (brightness) can be acquired.

  FIG. 2 is a block diagram showing the configuration of the far-infrared imaging device 1 according to the embodiment of the present invention. In FIG. 2, the image capturing unit 11 includes an image sensor that converts an optical signal into an electrical signal in a matrix. As the far-infrared imaging device, an infrared sensor such as a vanadium oxide bolometer using a micromachining technique or a pyroelectric type using a BSTO (Barium-Titanium Oxide) is used.

  The image capturing unit 11 reads infrared light around the vehicle as a luminance signal, and transmits the read luminance signal to the image processing circuit 10 that is an LSI substrate. In the present embodiment, an aperture mechanism 32 capable of adjusting the aperture amount is provided outside the objective lens 31. By adjusting the aperture amount by the aperture mechanism 32, the amount of light incident on the image pickup unit 11 can be reduced. adjust. The configuration of the diaphragm mechanism 32 is not particularly limited as long as it is a known diaphragm mechanism, and may be, for example, an unmounted type iris diaphragm or an assembly type iris diaphragm.

  The image processing circuit 10 includes a signal processing unit 12 and an image memory 13. The signal processing unit 12 converts the luminance signal received from the image capturing unit 11 into a digital signal, a process for removing various distortions generated in the optical system, a low-frequency noise removal process, and a correction process for correcting gamma characteristics Etc. Further, the luminance signal is converted into a YUV (Y: luminance, U, V: color difference) signal or the like according to the transmission format in the communication interface, and the converted signal is stored in the image memory 13 as image data. The signal processing unit 12 further receives the vehicle speed and / or surrounding illuminance acquired by the computing device 3, calculates an appropriate aperture degree by the aperture mechanism 32, and transmits an operation command to the actuator 33. The actuator 33 opens and closes the aperture mechanism 32 in accordance with the received operation command.

  The communication interface unit 14 is an LSI substrate, and sends image data stored in the image memory 13 to an external device and takes a captured image in accordance with a command received from the external device via the communication line 2 such as a communication cable. The conversion of the transfer rate according to the resolution of the data, the format conversion of the data for transmitting the image data, and the like are performed. The RAM 16 is an SRAM, a flash memory, or the like, and stores temporarily generated data in arithmetic processing, and also stores the correspondence between the vehicle speed and the aperture, and the correspondence between the ambient illuminance and the aperture. .

  The arithmetic device 3 receives the output image data and detects an obstacle using a known image recognition technique. The detected result is displayed on the display device 4 and the alarm device 5 is sounded as necessary to notify the driver of the presence of an obstacle. FIG. 3 is a block diagram showing a configuration of the arithmetic device 3 of the far infrared imaging system according to the embodiment of the present invention.

  The arithmetic device 3 is an image processing ECU, and includes at least an imaging device interface unit 31a, a video output unit 31b, a communication interface unit 31c, an image memory 32, and an LSI 33 incorporating a RAM 331.

  The imaging device interface unit 31 a inputs video signals from the far-infrared imaging devices 1, 1 and transfers detection values of the vehicle speed sensor 2 and / or the illuminance sensor 9 to the far-infrared imaging devices 1, 1. The imaging device interface unit 31a stores the image data input from the far-infrared imaging devices 1 and 1 in the image memory 32 in synchronization with one frame unit. The video output unit 31 b outputs image data to the display device 4 such as a liquid crystal display via the video cable 8.

  The communication interface unit 31 c transmits an output signal such as a synthesized sound to the alarm device 5 such as a buzzer or a speaker via the in-vehicle LAN cable 6. In addition, the communication interface unit 31 c receives the vehicle speed from the vehicle speed sensor 2 and the ambient illuminance from the illuminance sensor 9 via the in-vehicle LAN cable 6, and stores them in the RAM 331.

  The image memory 32 is an SRAM, flash memory, SDRAM or the like, and stores image data input from the far-infrared imaging devices 1 and 1 via the video input unit 31a.

  The LSI 33 that performs image processing reads the image data stored in the image memory 32 in units of frames, executes a known obstacle recognition process, a distance measurement process up to the obstacle, and the like, so that there is a possibility of collision with the obstacle. Judging. When the LSI 33 determines that there is a high possibility of colliding with an obstacle, the LSI 33 transmits an output signal such as a synthesized sound to the alarm device 5 via the communication interface unit 31c, or transmits a display signal to the display device 4. To do.

  Hereinafter, processing of the signal processing unit 12 of the far-infrared imaging device 1 used in the far-infrared imaging system according to the embodiment of the present invention will be described. FIG. 4 is a flowchart showing a processing procedure in the signal processing unit 12 of the far-infrared imaging device 1 according to the embodiment of the present invention.

  When the far-infrared imaging device 1 starts imaging, for example, when the power switch is turned on, the signal processing unit 12 receives the vehicle speed detected by the vehicle speed sensor 2 from the arithmetic device 3 (step S401). Then, the correspondence relationship between the vehicle speed and the throttle amount stored in the RAM 16 is inquired, and an appropriate throttle amount corresponding to the received vehicle speed is extracted (step S402). The aperture amount is stored in the RAM 16 in association with the required resolution, and the correspondence between the vehicle speed and the required resolution is also stored in the RAM 16.

  FIG. 5 is a diagram showing a correspondence relationship between the speed of the vehicle and the required resolution. As shown in FIG. 5, at 50 km / h, which is the average traveling speed of vehicles in Japan, an image can be taken without any problem if the resolution is 0.2 or higher. In addition, at 80 km / h or higher, a resolution of 0.4 or higher is generally required.

  The signal processing unit 12 extracts the required resolution based on the speed of the vehicle, and extracts the aperture amount stored in association with the extracted resolution. The signal processing unit 12 transmits an instruction signal for adjusting the aperture of the aperture mechanism 32 to the degree of opening of the aperture mechanism 32 corresponding to the extracted aperture amount to the actuator 33 of the aperture mechanism 32 (step S403). . The actuator 33 that has received the instruction signal gradually opens or closes the aperture mechanism 32 to the instructed opening degree.

  The image capturing unit 11 converts the incident infrared light into an electrical signal for each image sensor, and transmits the electrical signal to the signal processing unit 12. The signal processing unit 12 receives a luminance signal for each image sensor from the image capturing unit 11 (step S404).

  By doing so, for example, when the speed of the vehicle increases, the resolution can be improved by reducing the aperture amount of the aperture mechanism 32. Therefore, the output value of the image sensor can be made clearer. Conversely, when the speed of the vehicle decreases, the output value of the image sensor can be made clear by increasing the aperture amount of the aperture mechanism 32.

  The far-infrared imaging device 1 may store the correspondence relationship between the illuminance and the aperture amount in the RAM 16 and adjust the opening degree of the aperture mechanism 32 according to the brightness of the surroundings. That is, the signal processing unit 12 receives the illuminance indicating the brightness of the surroundings detected by the illuminance sensor 9 from the arithmetic device 3, inquires the correspondence relationship between the illuminance stored in the RAM 16 and the aperture amount, and received it. An appropriate aperture amount corresponding to the illuminance is extracted. The signal processing unit 12 transmits to the actuator 33 of the aperture mechanism 32 an instruction signal for adjusting the aperture amount of the aperture mechanism 32 so that the degree of opening of the aperture mechanism 32 corresponding to the extracted aperture amount is reached. The actuator 33 that has received the instruction signal gradually opens or closes the aperture mechanism 32 to the instructed opening degree.

  For example, when the periphery of the vehicle is bright, the temperature difference between the obstacle and the surrounding object is expected to be relatively small. Therefore, by increasing the aperture amount of the aperture mechanism 32, the resolution can be improved. Thus, even a slight difference in luminance value can be detected. On the other hand, when the periphery of the vehicle is dark, the temperature difference between the obstacle and the surrounding object is expected to be relatively large. Therefore, by reducing the aperture amount of the aperture mechanism 32, a slight movement can be achieved. On the other hand, it is possible to stably image an object without responding to the sensitivity.

  As described above, according to the present embodiment, the resolution is adjusted according to the situation by increasing or decreasing the degree of opening of the diaphragm mechanism 32 according to the speed of the vehicle and the brightness around the vehicle, that is, by increasing or decreasing the diaphragm amount. The output value of the image sensor can be made clearer.

  In the above-described embodiment, the case where the far-infrared imaging devices 1 and 1 are all equipped with the function of adjusting the opening degree of the aperture mechanism 32 has been described. The calculation device 3 may calculate the degree of opening of the aperture mechanism 32 and transmit it to the far infrared imaging devices 1 and 1.

It is a figure which shows typically the structure of the far-infrared imaging system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the far-infrared imaging device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the arithmetic unit of the far-infrared imaging system which concerns on embodiment of this invention. It is a flowchart which shows the process sequence in the signal processing part of the far-infrared imaging device concerning an embodiment of the invention. It is a figure which shows the correspondence of the speed of a vehicle, and the required resolution.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Far infrared imaging device 2 Vehicle speed sensor 3 Arithmetic device 9 Illuminance sensor 11 Image pick-up part 12 Signal processing part 13 Image memory 14 Communication interface part 15 Internal bus 16 RAM
31 Objective lens 32 Aperture mechanism 33 Actuator

Claims (2)

One or more lenses for focusing;
A plurality of imaging elements arranged in a matrix that converts light collected by the lens into an electrical signal;
A far-infrared imaging device comprising: an image processing circuit that forms an image based on an output value for each imaging element; and a vehicle speed sensor that detects a speed of a vehicle in which the far-infrared imaging device is mounted. In
The far-infrared imaging device is:
A diaphragm mechanism capable of gradually changing opening and closing on the front surface of the lens, and means for changing the opening degree of the diaphragm mechanism,
A far-infrared imaging system, wherein an opening degree of the aperture mechanism is changed according to a detection value of the vehicle speed sensor. An illuminance sensor that detects illuminance is further provided,
2. The far-infrared imaging system according to claim 1, wherein an opening degree of the diaphragm mechanism is changed according to a detection value of the illuminance sensor.

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