Patent Description:
In recent years, the installation of driver assistance systems in actual vehicles has progressed with the aim of realizing a safe and comfortable car society. Among them, systems that pursue the safety, convenience, and comfort of drivers and passengers have been developed such as a collision damage reduction braking control device that automatically performs a stop operation before a collision, an inter-vehicle distance control device that automatically tracks a preceding vehicle, and a lane departure prevention device, and sign recognition. Among such systems, importance of external environment recognition systems that recognize vehicles, pedestrians, and the like and measure the distance of an object have increased.

A stereo camera, which is one of the external environment recognition systems, extracts a feature point common to images from a pair of pieces of image information, and an integrated circuit performs a process of obtaining the number of pixels in which a position of the feature point is shifted between the pair of images to calculate the distance. Therefore, if there is a shift other than the original parallax between the pair of images, an error occurs in a distance measurement result. One of causes of the shift is a temperature increase due to sunlight, heat generation inside a device, or the like. If a temperature of an internal component exceeds an upper limit temperature, there is a concern that malfunction may occur and the life of the component may be shortened. Further, when a temperature difference occurs between a pair of left and right imaging elements, there is a concern that the measurement accuracy may deteriorate.

As the stereo camera, there is disclosed a heat radiation structure in which one end of a heat transfer portion that transfers heat from a part to a substrate holding portion is in contact with a heat generating part, and the other end of the heat transfer portion is in contact with the substrate holding portion on a line equidistant from imaging elements of two imaging devices, for example, as disclosed in PTL <NUM>. PTL <NUM> relates to a symmetrically provided vehicle-mounted image processing device. PTL <NUM> relates to a stereo camera device in which plural image pickup devices are mounted.

In the related art as described in PTL <NUM>, an operation failure is suppressed by suppressing a bias of a temperature distribution in an imaging unit. However, the length of the heat transfer portion, which is a heat transfer path, becomes long in the configuration using the heat transfer portion that transfers heat from a circuit element to the substrate holding portion, so that the thermal resistance increases.

Therefore, for example, when a temperature of a vehicle body side such as a windshield on which the stereo camera is installed increases due to sunlight or the like so that a temperature difference between the car body side and the stereo camera is insufficient or the temperature of the vehicle body side is higher than that of the stereo camera, it is conceivable that it is difficult to suppress a temperature increase in the stereo camera without sufficiently obtaining the heat radiation effect. In particular, an imaging element such as a CMOS, which is important for the stereo camera, often has a relatively lower upper limit temperature for guaranteeing an operation than other components, and it is conceivable that it is difficult to suppress a temperature increase in the imaging element.

The present invention has been made to solve such a problem, and a main object of the present invention is to provide a stereo camera device capable of reducing a temperature difference between a pair of left and right imaging elements and reducing a temperature increase in the imaging elements.

In order to solve the above-described problems, the present invention provides a stereo camera device having the features defined in claim <NUM>.

According to the present invention, it is possible to provide the stereo camera device capable of reducing the temperature difference between the pair of left and right imaging elements and reducing the temperature increase in the imaging elements.

Other objects, configurations, operations, and effects of the present invention which have not been described above become apparent from embodiments to be described hereinafter.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments, and various modifications and applications that fall within the technological concept of the present invention will be also included in the scope of the present invention.

Note that configurations denoted by the same reference signs have the same functions, and thus, descriptions of those that have already been described will be omitted unless otherwise specified. Further, orthogonal coordinate axes including an x axis, a y axis and a z axis will be described in the necessary drawings in order to clarify the description of positions of the respective parts.

An example of a stereo camera <NUM> (stereo camera device) of the present embodiment will be described. <FIG> is a perspective view illustrating an appearance of the stereo camera <NUM> according to a first embodiment of the present invention. <FIG> is a perspective view illustrating an internal configuration of the stereo camera <NUM> of <FIG>. <FIG> is a perspective view illustrating a yz plane of the stereo camera <NUM> of <FIG>. Further, <FIG> is a graph illustrating a temperature increase of a first imaging element 2a and a temperature increase of a second imaging element 2b depending on a length of a first distance (Lf) in the stereo camera <NUM> of <FIG>. Note that a description will be given in <FIG> by setting a Cartesian coordinate system including the x axis in which the front direction is positive in the front-back direction (optical-axis direction of a camera module) of the stereo camera <NUM>, the y axis in which the upward direction is positive in the up-down direction (height direction), and the z axis in which the right direction (right direction when facing the front direction) is positive in the left-right direction. In the graph of <FIG>, the horizontal axis represents the first distance, and the vertical axis represents the temperature increase of the first imaging element 2a and the temperature increase of the second imaging element 2b. Further, in the graph of <FIG>, the temperature increase of the first imaging element 2a is indicated by a broken line, and the temperature increase of the second imaging element 2b is indicated by a solid line. The first distance (Lf) is a distance from a first circuit element center <NUM> to a device center <NUM> (the stereo camera device center).

The device center <NUM> in a direction between camera modules 5a and 5b (the direction connecting the camera module 5a and the camera module 5b, that is, the z-axis direction) refers to an xy plane that has a line passing through a midpoint <NUM>, which divides a portion between the two imaging elements 2a and 2b mounted on the pair of left and right camera modules 5a and 5b into two portions, and connecting the imaging elements 2a and 2b as a normal line.

The first circuit element center <NUM> refers to a plane that is parallel to the xy plane and passes through a centroid <NUM> of the first circuit element <NUM>, and a second circuit element center <NUM> refers to a plane that is parallel to the xy plane and passes through a centroid <NUM> of the second circuit element <NUM> including an element groups of second circuit elements 7a, 7b, and 7c. Note that the centroid is used here for the sake of simplicity when obtaining the center, but the center of gravity or the heat generation center may be used instead.

A first imaging element center 18a refers to a plane parallel to the xy plane that passes through a first imaging element center 19a (a center of the optical first imaging element 2a including a lens and the like). Similarly, a second imaging element center 18b refers to a plane that is parallel to the xy plane and passes through a second imaging element center 19b (a center of the optical second imaging element 2b including a lens and the like).

As illustrated in <FIG> and <FIG>, the stereo camera <NUM> includes the first imaging element 2a and the second imaging element 2b, a first circuit element <NUM> and a second circuit element <NUM> disposed between the first imaging element 2a and the second imaging element 2b, and a casing 1a for retaining the first imaging element 2a, the first circuit element <NUM>, the second circuit element <NUM>, and the second imaging element 2b along the z axis in this order.

The first imaging element 2a is attached to the casing 1a as a set of the first camera module 5a including a first imaging element substrate 3a and a first lens 4a. Similarly, the second imaging element 2b is attached to the casing 1a as a set of the second camera module 5b including a second imaging element substrate 3b and a second lens 4b. The first circuit element <NUM> and the second circuit element <NUM> that process signals from the camera modules 5a and 5b are mounted on a circuit board <NUM>, and the first circuit element <NUM> and the second circuit element <NUM> are attached by being thermally connected to the casing 1a via a thermally conductive member <NUM>. At that time, there may be a plurality of the second circuit elements <NUM>, and <FIG> illustrates a case where three second circuit elements 7a to 7c are mounted.

Further, a cover <NUM> that covers a lower surface of the casing 1a has a structure that is attached to the casing 1a using a screw or the like. An electrical connection to the stereo camera <NUM> is made by connecting a wiring to an internal electrical connector through an opening (not illustrated) on a rear surface of the casing 1a.

The stereo camera <NUM> can image a front side of the stereo camera <NUM> using the pair of left and right camera modules 5a and 5b to image the front side of the stereo camera <NUM> and obtain parallax of an object from a pair of left and right captured images to obtain the distance to the object. Therefore, if there is a difference between the temperature of the first imaging element 2a and the temperature of the second imaging element 2b due to an increase in heat generation amount (power consumption) caused by high performance of the stereo camera <NUM> and a decrease in surface area due to miniaturization, there occurs a difference in external recognition between a signal of the first imaging element 2a and a signal of the second imaging element 2b, which causes a decrease in accuracy of the measurement distance or the like. Further, when the temperature of the first imaging element 2a or the temperature of the second imaging element 2b becomes high, a noise component of the signal increases and the measurement accuracy deteriorates. Similarly, malfunction or the like is caused if the temperature of the first imaging element 2a or the temperature of the second imaging element 2b becomes high.

The first circuit element <NUM> is, for example, a microcomputer, a signal processing element, a field programmable gate array (FPGA), or the like that processes an image signal, and refers to a circuit element that generates a large amount of heat and requires heat conduction to the casing 1a or the cover <NUM>. The second circuit elements 7a to 7c are, for example, double data rate (DDR) memories or the like, and are circuit elements used in the first circuit element <NUM>. The second circuit elements 7a to 7c may be circuit elements that are not used in the first circuit element <NUM>. The second circuit elements 7a to 7c refer to, for example, memories used for temporary storage of data, and the first circuit element <NUM> has a larger heat generation amount (power consumption) than the second circuit element <NUM>. A plurality of fins <NUM> for heat radiation are disposed in the upper part of the casing 1a at least between the first imaging element 2a and the second imaging element 2b.

The present embodiment relates to an arrangement of circuit elements, and a second distance (Lm) from the device center <NUM> to the second circuit element center <NUM> is longer than the first distance (Lf) from the device center <NUM> to the first circuit element center <NUM> in the direction between the camera modules 5a and 5b (z-axis direction). Further, a third distance (Lcr) from the first circuit element center <NUM> to the first imaging element center 18a is longer than the first distance (Lf) from the device center <NUM> to the first circuit element center <NUM> in the direction between the camera modules 5a and 5b (z-axis direction). Similarly, a fourth distance (Lcl) from the second circuit element center <NUM> to the second imaging element center 18b is longer than the second distance (Lm) from the device center <NUM> to the second circuit element center <NUM> in the direction between the camera modules 5a and 5b (z-axis direction).

Since the second distance (Lm) is longer than the first distance (Lf), heat generation centers of the first circuit element <NUM> and the second circuit element <NUM> can be disposed at the device center <NUM>, and the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal. As can be understood by referring to the temperature increase of the first imaging element 2a and the temperature increase of the second imaging element 2b depending on the length of the first distance (Lf) illustrated in <FIG>, the temperature of the first imaging element 2a can be reduced in a case where the first circuit element <NUM> is closer to the first imaging element 2a as compared to a case where the first circuit element <NUM> is located at a position closer to the device center <NUM>, and the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal. Further, when the temperature of the first imaging element 2a and the temperature of the second imaging element 2b at left and right sides are equal, a temperature distribution in the entire casing 1a is not biased. and the heat radiation performance of the stereo camera <NUM> is improved, so that the temperature of the first circuit element <NUM> and the temperature of the second circuit element <NUM> can also be reduced.

Further, when the third distance (Lcr) is longer than the first distance (Lf), in other words, the third distance (Lcr), which is the distance between the first circuit element <NUM> and the first imaging element 2a, is made longer, the heat radiation from the fins <NUM> and the like between the first circuit element <NUM> and the first imaging element 2a progresses, and the amount of heat transferred from the first circuit element <NUM> to the first imaging element 2a decreases, so that the temperature of the first imaging element 2a can be reduced. At that time, the efficient heat radiation is possible by providing the fins <NUM> between the first circuit element <NUM> and the first imaging element 2a, and the temperature of the first imaging element 2a can be reduced.

Similarly, when the fourth distance (Lcl) is longer than the second distance (Lm), in other words, the fourth distance (Lcl), which is the distance between the second circuit element <NUM> and the second imaging element 2b, is made longer, the heat radiation from the fins <NUM> and the like between the second circuit element <NUM> and the second imaging element 2b progresses, and the amount of heat transferred from the second circuit element <NUM> to the second imaging element 2b decreases, so that the temperature of the second imaging element 2b can be reduced. At that time, the efficient heat radiation is possible by providing the fins <NUM> between the second circuit element <NUM> and the second imaging element 2b, and the temperature of the second imaging element 2b can be reduced.

According to the present embodiment, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, and the stereo camera <NUM> with high measurement accuracy can be realized. Further, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high reliability can be realized. Further, the temperature of the first circuit element <NUM> and the temperature of the second circuit element <NUM> can be reduced, and the stereo camera <NUM> with high reliability can be realized.

Although the first imaging element 2a, the first circuit element <NUM>, the second circuit element <NUM>, and the second imaging element 2b are retained in this order along the z axis in the stereo camera <NUM> of the present embodiment, circuit elements may be retained to be left-right reversed such that the first imaging element 2a, the second circuit element <NUM>, the first circuit element <NUM>, and the second imaging element 2b are retained in this order along the z axis, and the arrangement may be plane-symmetrical in the xy plane with respect to the arrangement of the first embodiment. In the case of such an arrangement, in other words, the distance from the device center <NUM> to the center of the second circuit element <NUM> may be longer than the distance from the device center <NUM> to the center of the first circuit element <NUM> in the direction between the camera modules 5a and 5b, the distance from the center of the first circuit element <NUM> to the center of the second imaging element 2b may be longer than the distance from the device center <NUM> to the center of the first circuit element <NUM> in the direction between the camera modules 5a and 5b, and the distance from the center of the second circuit element <NUM> to the center of the first imaging element 2a may be longer than the distance from the device center <NUM> to the center of the second circuit element <NUM> in the direction between the camera modules 5a and 5b.

<FIG> is a perspective view illustrating a yz plane of a stereo camera <NUM> according to a second embodiment of the present invention. The stereo camera <NUM> has a casing 1b instead of the casing 1a of the stereo camera <NUM>. In <FIG>, the same configurations as those in the first embodiment will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

In the present embodiment, in a state where the second distance (Lm) is longer than the first distance (Lf), the third distance (Lcr) is longer than the first distance (Lf), and the fourth distance (Lcl) is longer than the second distance (Lm), there is a first extension portion <NUM> in which a first connection portion <NUM> connecting the first circuit element <NUM> and the casing 1b extends toward the second circuit element <NUM>. Alternatively, there is a second extension portion <NUM> in which a second connection portion <NUM> connecting the second circuit element <NUM> and the casing 1b extends toward the first circuit element <NUM>. Alternatively, there are both the first extension portion <NUM> and the second extension portion <NUM>.

Due to the first extension portion <NUM>, a heat generation center <NUM> on the casing 1b of the first circuit element <NUM> becomes closer to the second circuit element <NUM>, a distance Lcr2 from the first imaging element 2a to the heat generation center <NUM> of the first circuit element <NUM> in the direction between the camera modules 5a and 5b becomes longer, the heat radiation from fins <NUM> and the like between the first circuit element <NUM> and the first imaging element 2a progresses, and the amount of heat transferred from the first circuit element <NUM> to the first imaging element 2a decreases, so that a temperature of the first imaging element 2a can be reduced.

Similarly, due to the second extension portion <NUM>, a heat generation center <NUM> on the casing 1b of the second circuit element <NUM> becomes closer to the first circuit element <NUM>, a distance Lcl2 from the second imaging element 2b to the heat generation center <NUM> of the second circuit element <NUM> in the direction between the camera modules 5a and 5b becomes longer, the heat radiation from the fins <NUM> and the like between the second circuit element <NUM> and the second imaging element 2b progresses, and the amount of heat transferred from the second circuit element <NUM> to the second imaging element 2b decreases, so that a temperature of the second imaging element 2b can be reduced.

According to the second embodiment of the present invention, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high measurement accuracy and high reliability can be realized.

<FIG> is a perspective view illustrating a yz plane of a stereo camera <NUM> according to a third embodiment of the present invention. The stereo camera <NUM> has a casing 1c instead of the casing 1a of the stereo camera <NUM>. In <FIG>, the same configurations as those in the first and second embodiments will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

In the present embodiment, the first connection portion <NUM> (second embodiment) connecting the first circuit element <NUM> and the casing 1c and the second connection portion <NUM> (second embodiment) connecting the second circuit element <NUM> and the casing 1c are integrated to form a third connection portion <NUM>. An end surface of the third connection portion <NUM> in the -y-axis direction is flush at a position of the first circuit element <NUM>, a position between the first circuit element <NUM> and the second circuit element <NUM>, and a position of the second circuit element <NUM> in the z-axis direction.

In the present embodiment, due to the third connection portion <NUM>, the heat generation center <NUM> on the casing 1c of the first circuit element <NUM> is closer to the second circuit element <NUM>, and the heat generation center <NUM> on the casing 1c of the second circuit element <NUM> is similarly closer to the first circuit element <NUM>, which is similar to the second embodiment. Therefore, the distance Lcr2 from the first imaging element 2a to the heat generation center <NUM> of the first circuit element <NUM> in the direction between the camera modules 5a and 5b becomes longer, the heat radiation from the fins <NUM> and the like between the first circuit element <NUM> and the first imaging element 2a progresses, and the amount of heat transferred from the first circuit element <NUM> to the first imaging element 2a decreases, so that a temperature of the first imaging element 2a can be reduced. Further, the distance Lcl2 from the second imaging element 2b to the heat generation center <NUM> of the second circuit element <NUM> becomes longer, the heat radiation from the fins <NUM> and the like between the second circuit element <NUM> and the second imaging element 2b progresses, and the amount of heat transferred from the second circuit element <NUM> to the second imaging element 2b decreases, so that a temperature of the second imaging element 2b can be reduced.

According to the third embodiment of the present invention, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high measurement accuracy and high reliability can be realized.

<FIG> is a perspective view illustrating a yz plane of a stereo camera <NUM> according to a fourth embodiment of the present invention. The stereo camera <NUM> has a casing 1d instead of the casing 1a of the stereo camera <NUM>. In <FIG>, the same configurations as those in the first to third embodiments will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

In the present embodiment, the first connection portion <NUM> (second embodiment) connecting the first circuit element <NUM> and the casing 1d and the second connection portion <NUM> (second embodiment) connecting the second circuit element <NUM> and the casing 1d are integrated to form a fourth connection portion <NUM>. Then, a position <NUM> of the casing 1d in the height direction (y direction) is lowered within a range of the fourth connection portion <NUM> to make a plate thickness <NUM> of the casing 1d between the first circuit element <NUM> and the second circuit element <NUM> equal to that of the other places, and a fin height (fin length) <NUM> of fins <NUM> in the above range is made higher than a fin height (fin length) <NUM> of the other fins <NUM>.

In the present embodiment, due to the fourth connection portion <NUM>, the heat generation center <NUM> on the casing 1d of the first circuit element <NUM> is closer to the second circuit element <NUM>, and the heat generation center <NUM> on the casing 1d of the second circuit element <NUM> is similarly closer to the first circuit element <NUM>, which is similar to the second embodiment. Therefore, the distance Lcr2 from the first imaging element 2a to the heat generation center <NUM> of the first circuit element <NUM> in the direction between the camera modules 5a and 5b becomes longer, the heat radiation from the fins <NUM> and the like between the first circuit element <NUM> and the first imaging element 2a progresses, and the amount of heat transferred from the first circuit element <NUM> to the first imaging element 2a decreases, so that a temperature of the first imaging element 2a can be reduced. Further, the distance Lcl2 from the second imaging element 2b to the heat generation center <NUM> of the second circuit element <NUM> becomes longer, the heat radiation from the fins <NUM> and the like between the second circuit element <NUM> and the second imaging element 2b progresses, and the amount of heat transferred from the second circuit element <NUM> to the second imaging element 2b decreases, so that a temperature of the second imaging element 2b can be reduced. Further, since the fin height <NUM> between the first circuit element <NUM> and the second circuit element <NUM> is increased, the heat radiation performance can be improved, and the temperature of the first circuit element <NUM> and the temperature of the second circuit element <NUM> can be reduced. Further, since the plate thickness <NUM> of the casing 1d between the first circuit element <NUM> and the second circuit element <NUM> can be made equal to that of other places, the moldability of the casing 1d is improved, the dimensional accuracy is improved, and the reliability of the stereo camera <NUM> is also improved.

According to the fourth embodiment of the present invention, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high measurement accuracy and high reliability can be realized.

<FIG> is a perspective view illustrating a yz plane of a stereo camera <NUM> according to a fifth embodiment of the present invention. The stereo camera <NUM> has a casing 1e instead of the casing 1a of the stereo camera <NUM>. In <FIG>, the same configurations as those in the first and fourth embodiments will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

In the present embodiment, an end portion <NUM> of the first circuit element <NUM> on the first imaging element 2a side is disposed so as to be located within a width <NUM> of a fin <NUM> as illustrated in the enlarged view of <FIG> in the first embodiment in which the second distance (Lm) is longer than the first distance (Lf), the third distance (Lcr) is longer than the first distance (Lf), and the fourth distance (Lcl) is longer than the second distance (Lm). Since the end portion <NUM> of the first circuit element <NUM> on the first imaging element 2a side is located within the width <NUM> of the fin <NUM>, it is possible to efficiently radiate heat from the first circuit element <NUM> toward the first imaging element 2a and to reduce a temperature of the first imaging element 2a.

Similarly, if an end portion of the second circuit element <NUM> on the second imaging element 2b side is located within a width of a fin, it is possible to efficiently radiate heat from the second circuit element <NUM> toward the second imaging element 2b and to reduce a temperature of the second imaging element 2b.

According to the fifth embodiment of the present invention, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high measurement accuracy and high reliability can be realized.

<FIG> is a perspective view illustrating a zx plane (viewed from above) of a stereo camera <NUM> according to a sixth embodiment of the present invention. The stereo camera <NUM> has a casing 1f instead of the casing 1a of the stereo camera <NUM>. <FIG> is an A-A cross-sectional view of <FIG>. In <FIG> and <FIG>, the same configurations as those in the first and fifth embodiments will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

The first to sixth embodiments describe the distance between the camera modules 5a and 5b in the direction (z-axis direction).

Here, a connection center <NUM> of the first circuit element <NUM> to the casing 1f on the horizontal plane (zx plane) is a point obtained by projecting a centroid of the first circuit element <NUM> onto the horizontal plane, and a connection center <NUM> of the second circuit element <NUM> is a point obtained by projecting a centroid of the plurality of second circuit elements <NUM> onto the horizontal plane. Further, connection centers 39a and 39b of the first imaging element 2a and the second imaging element 2b are points obtained by projecting centers of surfaces attached to the casing 1f as the camera modules 5a and 5b onto the horizontal plane.

Considering distances in a direction between the camera modules 5a and 5b (z-axis direction) and in the optical-axis direction (x-axis direction), the first imaging element 2a and the second imaging element 2b, and the first circuit element <NUM> and the second circuit element <NUM> on the horizontal plane (zx plane) are disposed in the casings 1a to 1e substantially in a straight line as indicated by a broken line <NUM> in <FIG>, in the above-described respective embodiments.

In the present embodiment, for example, a distance (LLcr) between the connection center 39a of the first imaging element 2a and the connection center <NUM> of a first circuit element <NUM>' is increased to further reduce the influence of a temperature increase of the first circuit element <NUM>' on the first imaging element 2a. In the present embodiment, the first circuit element <NUM>' is disposed on the rear side of the optical axis (negative direction of the x axis) as indicated by a solid line in <FIG>. Similarly, the second circuit element <NUM>' may be disposed on the rear side of the optical axis (negative direction of the x axis) to increase a distance (LLcl) between the connection center 39b of the second imaging element 2b and the connection center <NUM> of the second circuit element <NUM>' in order to further reduce the influence of a temperature increase of the second circuit element <NUM>' including second circuit elements 7a', 7b'and 7c' on the second imaging element 2b. That is, when the first imaging element 2a and the second imaging element 2b are disposed on the front side of the stereo camera <NUM>, the first circuit element <NUM>' and the second circuit element <NUM>' may be disposed on the rear side of the stereo camera <NUM>.

The cross-sectional view of <FIG> is a view cut at a position of the first circuit element <NUM>' of the stereo camera <NUM> of <FIG>. As illustrated in <FIG>, the stereo camera <NUM> is located near a windshield <NUM>, and thus, the entire stereo camera <NUM> adopts a shape along the windshield <NUM>, that is, a shape in which a slope <NUM> is provided on a front side of a shape of a fin <NUM> in many cases. Therefore, when the first circuit element <NUM>' and the second circuit element <NUM>' are disposed on the rear side of the optical axis, a portion where a fin height <NUM> is high can be effectively used to improve the heat radiation performance, and it is possible to reduce a temperature of the first imaging element 2a, a temperature of the second imaging element 2b, a temperature of the first circuit element <NUM>' and a temperature of the second circuit element <NUM>', and to realize the stereo camera <NUM> with high reliability.

<FIG> is a cross-sectional view of a stereo camera <NUM> according to a seventh embodiment of the present invention cut at the same position as that in <FIG>. The stereo camera <NUM> has a casing <NUM> instead of the casing 1a of the stereo camera <NUM>. In <FIG>, the same configurations as those in the first and sixth embodiments will be denoted by the same reference signs, and detailed descriptions thereof will be omitted.

In the present embodiment, there is a third extension portion <NUM> in which the first connection portion <NUM> connecting the first circuit element <NUM>' and the casing <NUM> extends to the rear side of the optical axis (negative direction of the x axis), which is similar to the sixth embodiment. Due to the third extension portion <NUM>, a heat generation center on the casing <NUM> of the first circuit element <NUM>' becomes closer to the rear side of the optical axis, a distance from the first imaging element 2a to the heat generation center of the first circuit element <NUM>' becomes longer, the heat radiation from the fins <NUM> and the like between the first circuit element <NUM>' and the first imaging element 2a progresses, and the amount of heat transferred from the first circuit element <NUM>' to the first imaging element 2a decreases, so that a temperature of the first imaging element 2a can be reduced.

Similarly, if there is a fourth extension portion (not illustrated) in which the second connection portion <NUM> connecting the second circuit element <NUM>' and the casing 1f extends to the rear side of the optical axis (negative direction of the x axis), a heat generation center on the casing 1f of the second circuit element <NUM>' becomes closer to the rear side of the optical axis, a distance from the second imaging element 2b to the heat generation center of the second circuit element <NUM>' becomes longer, the heat radiation from the fins <NUM> and the like between the second circuit element <NUM>' and the second imaging element 2b progresses, and the amount of heat transferred to the second imaging element 2b decreases, so that a temperature of the second imaging element 2b can be reduced.

According to the seventh embodiment of the present invention, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be reduced, and the stereo camera <NUM> with high reliability can be realized.

<FIG> is a view illustrating a temperature increase of the first imaging element 2a and a temperature increase of the second imaging element 2b depending on a length of the first distance (Lf) in a stereo camera according to an eighth embodiment of the present invention. In the present embodiment, a structure of the stereo camera may be any of the first to seventh embodiments. Thus, a description will be given here with reference to the structure of the stereo camera <NUM> of the first embodiment. In the present embodiment, the first distance (Lf) is set based on an allowable range of a temperature difference between a temperature of the first imaging element 2a and a temperature of the second imaging element 2b.

Conditions that the second distance (Lm) is longer than the first distance (Lf), the third distance (Lcr) is longer than the first distance (Lf), and the fourth distance (Lcl) is longer than the second distance (Lm) can make the temperature of the first imaging element 2a and the temperature of the second imaging element 2b equal. At that time, a range of the length of the first distance (Lf), which is included in the allowable range of the temperature difference between the temperature of the first imaging element 2a and the temperature of the second imaging element 2b, which is allowable for the operation of the stereo camera <NUM>, is obtained by <FIG> as the range of <NUM> to <NUM>. That is, if the length of the first distance (Lf) is in the range of <NUM> to <NUM>, the temperature difference between the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be set within the range that is allowable for the operation of the stereo camera <NUM>. Therefore, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal by setting the first distance (Lf) within the range of <NUM> to <NUM>, and the stereo camera <NUM> with high measurement accuracy can be realized. At that time, the stereo camera <NUM> with high reliability can be realized even if a disturbance such as an assembly variation occurs.

Further, the first circuit element <NUM> has a larger heat generation amount (power consumption) than the second circuit element <NUM>, and a difference in the heat generation amount is three to five times. Therefore, it is preferable that the second distance (Lm) from the device center <NUM> to the second circuit element center <NUM> be longer than the first distance (Lf) from the device center <NUM> to the first circuit element center <NUM> in the direction between the camera modules 5a and 5b, and that the second distance (Lm) be three to five times the first distance (Lf).

According to the present embodiment, the temperature of the first imaging element 2a and the temperature of the second imaging element 2b can be made equal, and the stereo camera <NUM> with high measurement accuracy can be realized.

Claim 1:
A stereo camera device comprising:
a first imaging element (2a) and a second imaging element (2b) ;
a first circuit element (<NUM>) and a second circuit element (<NUM>) disposed between the first imaging element (2a) and the second imaging element (2b), wherein
the first circuit element (<NUM>) has a larger heat generation amount than the second circuit element (<NUM>); and
a casing (1a; 1b; 1c; 1d; 1e; 1f; <NUM>) for retaining the first imaging element (2a), the first circuit element (<NUM>), the second circuit element (<NUM>), and the second imaging element (2b) in order,
wherein a plane, which is passing through a midpoint (<NUM>) between the first imaging element (2a) and the second imaging element (2b) and which has a normal line connecting the first imaging element (2a) and the second imaging element (2b), is defined as a stereo camera device center (<NUM>),
a plane, which is passing through a centroid of the first imaging element (2a) and which has a normal line connecting the first imaging element (2a) and the second imaging element (2b), is defined as a first imaging element center (18a),
a plane, which is passing through a centroid of the second imaging element (2b) and which has a normal line connecting the first imaging element (2a) and the second imaging element (2b), is defined as a second imaging element center (18b),
a plane, which is passing through a centroid (<NUM>) of the first circuit element (<NUM>) and which has a normal line connecting the first imaging element (2a) and the second imaging element (2b), is defined as a first circuit element center (<NUM>),
a plane, which is passing through a centroid (<NUM>) of the second circuit element (<NUM>) and which has a normal line connecting the first imaging element (2a) and the second imaging element (2b), is defined as a second circuit element center (<NUM>),
a second distance (Lm) from the second circuit element center (<NUM>) to the stereo camera device center (<NUM>) is longer than a first distance (Lf) from the first circuit element center (<NUM>) to the stereo camera device center (<NUM>) in a direction connecting the first imaging element (2a) and the second imaging element (2b),
a third distance (Lcr) from the first circuit element center (<NUM>) to the first imaging element center (18a) is longer than the first distance (Lf), and
a fourth distance (Lcl) from the second circuit element center (<NUM>) to the second imaging element center (18b) is longer than the second distance (Lm).