JP2009267918A - Stereo camera, stereo imaging method and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stereo camera, stereo imaging method and program for suppressing a failure rate to extend a service life by expanding operating temperature range in the installation area to reduce thermal load. <P>SOLUTION: The stereo camera 100 includes: lenses 101 and 102 receiving light from an imaging object, imaging elements A103 and B104 for converting the light from the imaging object to electrical signals, amplifying circuits A105 and B106 for amplifying the converted electrical signals, a stereo image processing circuit 107 for performing stereo image processing, a light source circuit 108 for driving a light source for radiating the lights to the imaging object, and a temperature detecting circuit 109 for detecting atmospheric temperature. The temperature detecting circuit 109 is structured to output, to the light source circuit 108, If control information for controlling a light source current If applied to the light source from the light source circuit 108. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a stereo camera that performs stereo distance measurement, a stereo imaging method, and a program thereof.

  In a conventional stereo camera, a plurality of cameras are used to detect the distance from the camera to an object to be photographed (see, for example, Patent Document 1). FIG. 6 is a diagram showing a schematic configuration of a conventional stereo camera.

In FIG. 6, the light emission control unit 508 performs control so that the back irradiation light source 509 that illuminates the rear of the vehicle is operated in accordance with the rear operation of the clutch means 507 of the vehicle. Signals of images picked up by the image pickup means 501 and 502 are digitized by the A / D buffers 503 and 504, respectively, and then input to the stereo image processing means 505, from the image pickup means 501 and 502 to the vehicle rear object. The distance is calculated. The output device 506 generates an alarm when the rear object approaches. By illuminating the object with the back irradiation light source 509, the image signal levels of the imaging units 501 and 502 are increased, so that the accuracy of stereo image processing, that is, the accuracy of distance calculation can be improved even in a dark environment.
JP 2003-2138 A

  However, in the above-described conventional technology, in particular, when a stereo camera is disposed in the vehicle interior and the light source is close to the imaging means of the stereo camera, the image sensor and the light source are driven in addition to the temperature rise in the vehicle interior in fine weather. As the internal temperature rises due to self-heating due to the fact that the ambient temperature where the stereo camera is located becomes the upper limit temperature at which it can operate, it is likely to break down and it is expected that the life will be shortened Is done.

  FIG. 7 is an explanatory diagram of the temperature rise of a conventional stereo camera. The horizontal axis indicates the ambient temperature ta where the stereo camera is arranged, and the vertical axis indicates the camera temperature ti, which is the temperature of the stereo camera. Patent Document 1 does not describe that the back irradiation light source 509 is close to the imaging units 501 and 502, but is not limited to the arrangement of the light source at the rear of the vehicle to irradiate the rear of the vehicle. Are close to each other and the light source is energized (in FIG. 7, when a small current If is passed), the camera temperature ti becomes higher than the ambient temperature ta (= taj2). In particular, when the current value flowing through the light source is large (If large), the light source further generates heat, so that the temperature rise of the stereo camera becomes significant, and the ambient temperature taj reaching the operating temperature limit tj is decreased to taj1 from taj2. For this reason (taj1 <taj2), there is a problem that the ambient temperature range in which stable operation is performed becomes narrow, and failure tends to occur when the ambient temperature exceeds taj1.

  The present invention has been made in order to solve the conventional problems. A stereo camera and a stereo that can suppress the failure rate and extend the life by extending the operating temperature range at the installation location to reduce the thermal burden. An object is to provide an imaging method and a program thereof.

  The stereo camera of the present invention controls an imaging unit that images a subject, a light source that irradiates the subject, a temperature detection unit that detects a temperature, and a light source current that flows to the light source according to a detection result of the temperature detection unit. And a light source current control means.

  With this configuration, in the stereo camera of the present invention, the light source current control unit controls the light source current that flows to the light source according to the detection result of the temperature detection unit, so the operating temperature range at the installation location is expanded to reduce the thermal burden. Therefore, the failure rate can be suppressed and the life can be extended.

  In the stereo camera of the present invention, the light source current control means limits the light source current when the detected temperature coincides with a predetermined temperature.

  With this configuration, the stereo camera of the present invention can limit the light source current at a predetermined temperature, thereby extending the operating temperature range at the installation location and reducing the thermal burden, thereby reducing the failure rate and extending the life. it can.

  Furthermore, the stereo camera of the present invention includes an amplification unit that amplifies the output signal of the imaging unit and an amplification factor control unit that controls the amplification factor of the amplification unit according to the detection result of the temperature detection unit. have.

  With this configuration, when the temperature rises, the stereo camera of the present invention allows the amplification rate control means to amplify the amplification means even when the image signal level is reduced as the light amount of the light source is reduced by the control of the light source current control means. Therefore, the image signal level can be increased, and a decrease in accuracy of distance measurement can be suppressed.

  The stereo imaging method of the present invention includes a step of imaging with an imaging device, a step of detecting a temperature, and a step of controlling a light source current that flows to the light source according to the temperature detected in the step of detecting the temperature. It has a configuration.

  With this configuration, the stereo imaging method of the present invention controls the light source current that flows through the light source in accordance with the temperature detection result in the step of controlling the light source current. By reducing it, the failure rate can be suppressed and the life can be extended.

  Further, the stereo imaging method of the present invention has a configuration including a step of limiting the light source current when the temperature detected in the step of detecting the temperature coincides with a predetermined temperature.

  With this configuration, the stereo imaging method of the present invention limits the light source current at a predetermined temperature, thereby extending the operating temperature range at the installation location and reducing the thermal burden, thereby reducing the failure rate and extending the life. Can do.

  Furthermore, the stereo imaging method of the present invention includes a step of amplifying the output signal of the imaging device and a step of controlling the amplification factor of the output signal according to the temperature detected in the step of detecting the temperature. have.

  With this configuration, in the stereo imaging method of the present invention, the step of controlling the amplification factor even when the image signal level decreases as the light amount of the light source decreases in the step of controlling the light source current when the temperature rises. Since the amplification factor of the output signal can be increased, the image signal level can be increased, and a decrease in accuracy of distance measurement can be suppressed.

  The stereo imaging program of the present invention has a configuration that causes a computer or microcomputer to execute a stereo imaging method.

  With this configuration, the stereo imaging program of the present invention causes the computer or microcomputer to control the light source current that flows to the light source in accordance with the temperature detection result in the step of controlling the light source current, thereby extending the operating temperature range at the installation location. By reducing the thermal burden, the failure rate can be reduced and the service life can be extended.

  The present invention provides a stereo camera, a stereo imaging method, and a program thereof that have the effect of suppressing the failure rate and extending the service life by extending the operating temperature range at the installation location to reduce the thermal burden. It can be done.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A configuration of the stereo camera according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram of a stereo camera according to the present embodiment.

  As shown in FIG. 1, the stereo camera 100 according to the present embodiment includes a lens 101 and a lens 102 that receive subject light, an image sensor A103 and an image sensor B104 that convert the subject light into electrical signals, and an electrical signal that is amplified. An amplification circuit A105 and an amplification circuit B106, a stereo image processing circuit 107 that performs stereo image processing, a light source circuit 108 that drives a light source (not shown) that irradiates the subject with light, and a temperature detection circuit 109 that detects the ambient temperature And.

  Note that the image sensor A103 and the image sensor B104 constitute an imager according to the present invention. In addition, the amplifier circuit A105 and the amplifier circuit B106 constitute an amplifier unit according to the present invention. Further, the light source circuit 108 and the temperature detection circuit 109 constitute a light source current control unit according to the present invention. Further, the temperature detection circuit 109 constitutes temperature detection means according to the present invention.

  In FIG. 1, a stereo camera 100 forms an image on an image sensor A103 using a lens 101, and an amplifier circuit A105 amplifies an output signal of the image sensor A103 and supplies a signal to a stereo image processing circuit 107. The stereo camera 100 forms an image on the image sensor B 104 using the lens 102, and the amplifier circuit B 106 amplifies the output signal of the image sensor B 104 and supplies a signal to the stereo image processing circuit 107.

  The stereo image processing circuit 107 performs a process for obtaining distance information based on the principle of triangulation from a corresponding positional deviation amount for a stereo image based on two input image signals, thereby obtaining a three-dimensional distance distribution. A distance image signal to be expressed is generated and output.

  The light source circuit 108 obtains If control information for controlling the light source current If flowing to the light source from the temperature detection circuit 109, and controls the light source current If output to the light source based on the If control information. The temperature detection circuit 109 detects the ambient temperature of the stereo camera 100 and outputs If control information corresponding to the detected temperature to the light source circuit 108.

  Next, control of the light source circuit 108 by the temperature detection circuit 109 will be described with reference to FIGS. FIG. 2 is a diagram illustrating a relationship among the ambient temperature ta, the camera temperature ti, and the light source current If of the stereo camera 100 according to the present embodiment.

  The temperature detection circuit 109 controls the light source circuit 108 so that a large If current flows through the light source when the ambient temperature ta is in the range of ta <ta1. Further, the temperature detection circuit 109 controls the light source circuit 108 so as to gradually decrease the current flowing through the light source from the large If to the If if the ambient temperature ta is in the range of ta1 ≦ ta <ta2. Further, the temperature detection circuit 109 gradually decreases the current passed through the light source from If if the ambient temperature ta is in the range of ta2 ≦ ta <ta3, and does not supply the light source with the light source current If = 0 at the ambient temperature ta = ta3. The light source circuit 108 is controlled. Here, the current passed through the light source has a relationship of “If Large> If Medium> 0”, and the values of “If Large” and “If” are determined in advance according to the light source, the use environment, and the like.

  As described above, by limiting the light source current If as the ambient temperature ta rises, the ambient temperature taj at which the camera temperature reaches the operating temperature limit tj can be increased from the conventional taj1 to ta3, and the camera temperature rise is increased. Suppressing and extending the operating temperature range of the atmosphere. That is, the relationship between the light source current If and the ambient temperature ta can be expressed in FIG.

  Note that the control of the light source current If by the light source circuit 108 and the temperature detection circuit 109 can be realized by, for example, a computer or a microcomputer. As shown in FIG. 3, by causing a computer or microcomputer to execute a program programmed to decrease the light source current If according to the ambient temperature ta, and inputting temperature data detected by the temperature detection circuit 109 to the computer or microcomputer, A computer or microcomputer can control the light source current If.

  As described above, according to the stereo camera 100 in the present embodiment, since the temperature detection circuit 109 that controls the light source circuit 108 according to the detected ambient temperature is provided, the operating temperature range at the installation location is expanded. By reducing the thermal burden, the failure rate can be suppressed and the life can be extended.

  In the above-described embodiment, the temperature detection circuit 109 detects the ambient temperature and gradually decreases the light source current If according to the increase in the ambient temperature. However, the present invention is not limited to this. For example, the temperature detection circuit 109 may detect the temperature inside the camera and gradually reduce the light source current If according to the temperature inside the camera.

  In the above-described embodiment, the process in which the temperature detection circuit 109 controls the light source current If via the light source circuit 108 includes not only the process of increasing / decreasing the light source current If according to the detection temperature, but also the detection temperature in advance. A process of setting the light source current If = 0 when a predetermined temperature is reached is also included.

(Second Embodiment)
A configuration of the stereo camera according to the second embodiment of the present invention will be described. FIG. 4 is a block diagram of the stereo camera in the present embodiment.

  As shown in FIG. 4, the stereo camera 200 in the present embodiment is different from the stereo camera 100 in the first embodiment in that a gain adjustment circuit 201 is provided. The description is omitted.

  The gain adjustment circuit 201 acquires temperature information from the temperature detection circuit 109, and adjusts the gain (amplification factor) of the amplification circuit A105 and the amplification circuit B106 to a desired value according to the ambient temperature. The gain adjusting circuit 201 constitutes an amplification factor control unit according to the present invention.

  FIG. 5 is a diagram showing gain characteristics of the amplifier circuit A105 and the amplifier circuit B106 with respect to the ambient temperature ta of the stereo camera 200 in the present embodiment, and the operation of the stereo camera 200 will be described based on this.

  The temperature detection circuit 109 detects the ambient temperature and outputs temperature information to the gain adjustment circuit 201. Next, as shown in FIG. 5, the gain adjustment circuit 201 sets the gains of the amplifier circuit A105 and the amplifier circuit B106 to a constant value of G1 when the ambient temperature ta is in the range of ta <ta1. The gain adjustment circuit 201 controls the gains of the amplifier circuit A105 and the amplifier circuit B106 so that the gain gradually increases from G1 to G2 when the ambient temperature ta is in the range of ta1 ≦ ta <ta2. Furthermore, the gain adjustment circuit 201 controls the gains of the amplifier circuit A105 and the amplifier circuit B106 so that the gain gradually increases from G2 to G3 when the ambient temperature ta is in the range of ta2 ≦ ta <ta3.

  By the way, in the first embodiment, when the ambient temperature increases, the image signal level decreases as the light amount of the light source decreases, and the image becomes dark and difficult to be seen as an image. 107 may not be able to perform the ranging function operation. Therefore, in the present embodiment, the gain of the amplifier circuit A105 and the amplifier circuit B106 is set to a gain that is linked to the detected temperature, thereby increasing the image signal level given to the stereo image processing circuit 107 so as to compensate for the decrease in the light amount of the light source. The distance measuring function operation can be continued.

  The gain control of the amplifier circuit A105 and the amplifier circuit B106 by the gain adjustment circuit 201 can be realized by a computer or a microcomputer, for example. As shown in FIG. 5, by causing a computer or a microcomputer to execute a program programmed to increase the gain of the amplifier circuit in accordance with the ambient temperature ta and inputting temperature data detected by the temperature detection circuit 109 to the computer or microcomputer. The computer or the microcomputer can control the gains of the amplifier circuit A105 and the amplifier circuit B106.

  As described above, the stereo camera 200 according to the present embodiment includes the gain adjustment circuit 201 that controls the gains of the amplification circuit A 105 and the amplification circuit B 106 according to the temperature information from the temperature detection circuit 109. The gain adjustment circuit 201 can increase the gains of the amplifier circuit A105 and the amplifier circuit B106 even when the image signal level decreases as the light amount of the light source decreases due to the control of the temperature detection circuit 109 when the temperature increases. Therefore, the image signal level input by the stereo image processing circuit 107 can be increased, and the distance measuring function operation can be continued.

  In the above embodiment, the temperature detection circuit 109 detects the ambient temperature and the gain adjustment circuit 201 gradually increases the gain according to the increase in the ambient temperature. However, the present invention is not limited to this. For example, the temperature detection circuit 109 may detect the temperature inside the camera, and the gain adjustment circuit 201 may gradually increase the gain according to the temperature inside the camera.

  The control process of the amplifier circuit performed by the gain adjustment circuit 201 is not only a process of increasing / decreasing the gain according to the detected temperature, but if the detected temperature is lower than a predetermined temperature, the gain G = G1, which is equal to or higher than a certain temperature. Then, the process of setting the gain G = G3 or the like is also included.

  The stereo camera according to the present invention is capable of limiting the amount of light so as to suppress the amount of heat generated by detecting the temperature in view of a failure due to high temperature in the vehicle interior and self-heating, thus reducing the failure rate, This is useful as a stereo camera that can extend the service life.

The block diagram which shows the structure in 1st Embodiment of the stereo camera which concerns on this invention. The figure which shows the relationship between atmospheric temperature ta, camera temperature ti, and light source current If in 1st Embodiment of the stereo camera which concerns on this invention. The figure which shows the relationship of the light source current If with respect to atmospheric temperature ta in 1st Embodiment of the stereo camera which concerns on this invention. The block diagram which shows the structure in 2nd Embodiment of the stereo camera which concerns on this invention. The figure which shows the camera gain characteristic with respect to atmospheric temperature ta in 2nd Embodiment of the stereo camera which concerns on this invention. Block diagram showing the configuration of a conventional stereo camera Explanatory diagram of temperature rise of conventional stereo camera

Explanation of symbols

100, 200 Stereo camera 101, 102 Lens 103 Image sensor A (imaging means)
104 Image sensor B (imaging means)
105 Amplifying circuit A (amplifying means)
106 Amplification circuit B (amplification means)
107 stereo image processing circuit 108 light source circuit (light source current control means)
109 Temperature detection circuit (temperature detection means, light source current control means)
201 Gain adjustment circuit (gain control means)

Claims (7)

An imaging means for imaging a subject, a light source for illuminating the subject, a temperature detection means for detecting temperature, and a light source current control means for controlling a light source current that flows to the light source according to a detection result of the temperature detection means Stereo camera characterized by having. The stereo camera according to claim 1, wherein the light source current control means limits the light source current when the detected temperature coincides with a predetermined temperature. The amplification means for amplifying the output signal of the imaging means, and the amplification factor control means for controlling the amplification factor of the amplification means according to the detection result of the temperature detection means. Stereo camera described in 1. A stereo imaging method comprising the steps of: taking an image with an imaging device; detecting a temperature; and controlling a light source current to be supplied to the light source in accordance with the temperature detected in the temperature detecting step. . The stereo imaging method according to claim 4, further comprising a step of limiting the light source current when the temperature detected in the step of detecting the temperature matches a predetermined temperature. 6. The method according to claim 4, further comprising: amplifying an output signal of the imaging device; and controlling an amplification factor of the output signal according to the temperature detected in the step of detecting the temperature. The stereo imaging method described. A stereo imaging program for causing a computer or a microcomputer to execute the stereo imaging method according to any one of claims 4 to 6.

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