Stereo camera

Abstract

Provided is a camera device that reduces production costs by shortening the time of assembly work when a camera module is mounted to a housing, and that can also enhance mounting accuracy of the camera module to the housing. Accordingly, this camera device is configured to include a lens unit including: a lens barrel part in which a plurality of lenses are stored; a reference surface, which is a surface perpendicular to the optical axis of the lenses, and which is made to abut an external abutting surface; and a positioning structure that fixes the center position of the lenses or restricts the movement in the rotating direction thereof, in a state where the reference surface is made to abut the abutting surface.

Description

[Technical Field]

[0001] The present invention relates to a camera device having a lens unit. [Background technology]

[0002] Automotive stereo cameras (hereinafter referred to as "camera devices"), a type of external recognition sensor for advanced driver assistance systems (ADAS) and autonomous driving (AD) systems, are devices that calculate disparity information from left and right images captured synchronously by left and right cameras, and measure the distance (hereinafter referred to as "distance measurement") to the captured objects (other vehicles, pedestrians, obstacles, etc.). Because distance measurement by a camera device is based on the disparity information of the left and right images, to achieve accurate distance measurement, the left and right camera modules must be precisely fixed to the housing so that the disparity information can be accurately calculated.

[0003] 8 is an exploded perspective view of the main parts of a typical camera device, as viewed from the front. This camera device includes a highly rigid housing 100 that forms the front shell of the camera device, a left camera module 1L fixed to the left rear surface of housing 100, and a right camera module 1R fixed to the right rear surface of housing 100. If the distance between the optical axes of the two camera modules is defined as base length L, the angle around the optical axis of left camera module 1L is defined as roll angle θL, and the angle around the optical axis of right camera module 1R is defined as roll angle θR, then in order to ensure the desired distance measurement accuracy with this camera device, it is necessary to suppress errors in the parallelism of the two optical axes, base length L, and roll angles θL and θR within predetermined ranges allowed by the specifications of the camera device.

[0004] Here, the in-vehicle imaging device of Patent Document 1 is known as a conventional technique for attaching a camera module to a housing of a camera device with high precision. For example, paragraph 0018 of the document states, "The present invention aims to provide an in-vehicle imaging device that allows high-precision adjustment of the optical axis of an imaging unit relative to the housing while minimizing precision machining of the housing," and paragraph 0019 states, "The present invention includes an imaging element unit having a lens and a lens holder on which three reference surfaces are formed, the reference surfaces being normal to the optical axis of the lens and surrounding the lens when viewed from the optical axis direction of the lens; and a housing having an insertion portion through which the lens holder is inserted, an opposing surface facing the reference surfaces, and three adhesive-filled portions that penetrate from the opposing surface side to the opposite surface side of the opposing surface and are arranged to surround the insertion portion, wherein the relative positions of the imaging element unit and the housing are fixed only by the adhesive in the three adhesive-filled portions."

[0005] In this way, Patent Document 1 enables highly accurate optical axis adjustment by filling the adhesive filling section of the housing with adhesive while the reference surface of the lens holder is in contact with the opposing surface of the housing, and fixing the positional relationship between the housing and the lens holder. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6941686 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, there has been a demand for further cost reductions in camera devices, and Patent Document 1 also aims to reduce costs by using adhesive to fix the positional relationship between the housing and the lens holder, thereby minimizing the processing costs required for precise processing and molding of the housing (see paragraph 0059 of the same document, etc.).

[0008] Furthermore, with regard to the camera structure for improving assembly efficiency and reducing costs, for example, paragraph 0065 of the same document states, "In the camera module 20L1 of this embodiment shown in Figures 5A and 5B, a concave shape 25L1 is formed on a reference plane 24L1 whose normal is the optical axis of the lens held in the lens holder 21L1, and inside the concave shape 25L1, as shown in Figure 5C, a convex shape 26L1 that is recessed below the reference plane 24L1. The concave shape 25L1 and the convex shape 26L1 are formed at positions that serve as landmarks when the reference plane 24L1 is viewed from the adhesive filling portion 14L of the housing 10."

[0009] However, even when this camera structure is adopted, the assembly procedure remains the same: the position of the lens holder is adjusted so that the marks (convex or concave) on the reference surface are visible when looking into the reference surface of the lens holder through the adhesive-filled portion of the housing, and then adhesive is filled into the adhesive-filled portion of the housing to fix the positional relationship between the housing and the lens holder. Therefore, the need to adjust the position of the lens holder while looking into the adhesive-filled portion reduces production efficiency and hinders further cost reduction. In addition, the marks are only reference points for adjusting the position of the lens holder, and the marks themselves do not have the function of regulating the positional relationship between the housing and the lens holder, so there is also the problem that simply providing the marks does not sufficiently ensure the accuracy of the positional relationship between the housing and the lens holder.

[0010] Therefore, the present invention aims to provide a camera device that can reduce production costs by shortening the assembly time required to attach a camera module to a housing, while also improving the accuracy of attaching the camera module to the housing. [Means for solving the problem]

[0011] In order to solve the above problems, the camera device of the present invention is a camera device having a lens unit, which has a barrel portion storing multiple lenses, a reference surface that is perpendicular to the optical axis of the lens and abuts against an external abutment surface, and a positioning structure that fixes the center position of the lens or restricts movement in the rotational direction when the reference surface is abutted against the abutment surface. [Effects of the Invention]

[0012] The camera device of the present invention can reduce production costs by shortening the assembly time required to attach the camera module to the housing, while also improving the accuracy of attaching the camera module to the housing. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is an exploded perspective view of the main part of the camera device according to the embodiment, seen from the rear. [Figure 2] FIG. 1 is a perspective view of a camera module according to an embodiment. [Figure 3] FIG. 2 is a top view of a camera module according to an embodiment. [Figure 4] FIG. 4 is an enlarged view of a left camera module attachment portion on the rear surface of the housing of the embodiment. [Figure 5A] 3A to 3C are diagrams illustrating a manufacturing procedure for a camera module according to an embodiment. [Figure 5B] 3A to 3C are diagrams illustrating a manufacturing procedure for a camera module according to an embodiment. [Figure 5C] 3A to 3C are diagrams illustrating a manufacturing procedure for a camera module according to an embodiment. [Figure 6] 3A to 3C are diagrams illustrating a manufacturing procedure for a camera module according to an embodiment. [Figure 7] 3A to 3C are diagrams illustrating a manufacturing procedure for a camera module according to an embodiment. [Figure 8] FIG. 1 is an exploded perspective view of a main part of a general camera device as viewed from the front. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a camera device according to the present invention will be described with reference to the drawings.

[0015] <Camera device structure> First, the structure of a camera device according to one embodiment will be described with reference to FIGS.

[0016] Fig. 1 is an exploded perspective view of the main parts of the camera device of this embodiment as seen from the rear. The structure of the camera device of this embodiment is basically the same as that of Fig. 8 described above, but differs in the shape of the contact portion between the housing 100 and the camera module 1, which will be described later. The camera device of this embodiment also includes a main control board that controls the camera module 1, processes the output signal of the camera module 1 to generate an image, and compares the left and right images to calculate parallax information, as well as a back cover that covers the back of the housing 100, but these are not shown in Fig. 1.

[0017] 2 is a perspective view of the camera module 1, and FIG. 3 is a top view of the camera module 1. As shown in both figures, the camera module 1 has a lens unit 10, an imaging element substrate 20, and wiring 30.

[0018] Lens unit 10 is a resin part that holds multiple lenses and fixes camera module 1 to housing 100, and is formed by integrally molding a lens barrel portion 11 that stores multiple lenses in series, multiple reference surfaces 12 that are arranged on the same plane perpendicular to the optical axis of lens barrel portion 11, and multiple positioning pins 13 that are structures for fixing camera module 1 to housing 100. Note that while Figures 2 and 3 illustrate a structure in which three reference surfaces 12 are arranged in a substantially equilateral triangle shape surrounding lens barrel portion 11 and two positioning pins 13 are arranged on the same plane that includes the optical axis of lens barrel portion 11, the number and arrangement of reference surfaces 12 and positioning pins 13 are not limited to those shown in the drawings, as long as three or more reference surfaces 12 are arranged to surround lens barrel portion 11 and two or more positioning pins 13 are arranged to surround lens barrel portion 11.

[0019] The imaging element substrate 20 is a substrate on which the imaging element 21 is arranged on the optical axis of the lens barrel portion 11, and is fixed to the lens unit 10 in a procedure described below. The imaging element 21 is a CMOS image sensor or the like that captures an image in the optical axis direction through the lens barrel portion 11.

[0020] The wiring 30 is an FPC (Flexible Printed Circuits) or an FFC (Flexible Flat Cable) that connects the imaging element board 20 to the main control board and the like.

[0021] 4 is a rear view of the housing 100, showing an enlarged view of the vicinity of the fixing part of the left camera module 1L. Note that the vicinity of the fixing part of the right camera module 1R has a similar structure, so the description of the fixing part on the right side will be omitted below.

[0022] As shown here, three abutment surfaces 101 are provided on the back surface of the housing 100 at positions opposite the three reference surfaces 12 of the lens unit 10, a positioning hole 102 is provided at a position opposite one of the positioning pins 13 of the lens unit 10, and a positioning elongated hole 103 is provided at a position opposite the other positioning pin 13.

[0023] With this structure, the left camera module 1L can be fixed to the housing 100 with the three reference surfaces 12 abutting against the opposing abutment surfaces 101 and with the two positioning pins 13 inserted into the opposing positioning holes 102 and elongated positioning holes 103. Note that the elongated positioning holes 103 are formed long in the linear direction connecting the positioning holes 102 and the elongated positioning holes 103, so that even if there is some variation in the distance between the positioning pins 13 of the lens unit 10, both positioning pins 13 can be inserted into the positioning holes 102 and the elongated positioning holes 103.

[0024] In this embodiment, the lens unit 10 and the housing 100 are positioned by inserting the pin of the lens unit 10 into the hole of the housing 100, but the lens unit 10 and the housing 100 may be positioned by inserting the pin of the housing 100 into the hole of the lens unit 10. Also, the lens unit 10 and the housing 100 may be positioned by providing a recess into which the lens unit 10 is fitted.

[0025] <Mechanism to suppress errors in the parallelism of the camera's optical axis, baseline length L, and roll angle θ> The mechanism by which the above structure reduces errors in the parallelism of the left and right optical axes of the camera device of this embodiment, the base line length L, and the left and right roll angles θL and θR (see FIG. 8) will be described.

[0026] As described above, the multiple reference surfaces 12 of the lens unit 10 are formed on the same plane perpendicular to the optical axis of the barrel portion 11 of the lens unit 10 (i.e., the optical axis of the camera module 1). Furthermore, the multiple abutment surfaces 101 of the housing 100 are formed as planes facing each of the multiple reference surfaces 12 formed on the same plane, and therefore the abutment surfaces 101 are also formed on the same plane.

[0027] Therefore, when attaching the left and right camera modules 1L, 1R to the housing 100, pressing the reference surface 12, to which the optical axes of the left and right lens units 10 are normal, against the opposing abutment surface 101 of the housing 100 is equivalent to pressing the reference surfaces 12 of the left and right camera modules 1L, 1R against the same plane, and the optical axes of the left and right camera modules 1L, 1R, which are perpendicular to the same plane, become parallel to each other.

[0028] In order for the camera device to calculate accurate parallax information, it is necessary to make the left and right optical axes parallel to each other, ensure that the distance between the optical axes (baseline length L) of the left and right camera modules 1L and 1R is within a specified value, and ensure that the left and right roll angles θL and θR are within specified values.

[0029] In the camera module 1 of this embodiment, a pair of positioning pins 13 provided on the lens unit 10 are fitted into the positioning hole 102 and the positioning elongated hole 103 of the housing 100, so that each positioning pin 13 serves as a reference for positioning relative to the housing 100 and a reference for roll rotation relative to the housing 100, making it possible to simultaneously suppress errors in the position and roll angle θ of the camera module 1.

[0030] 8, roll angle θ is the angle of rotation of camera module 1 around the optical axis as the axis of rotation, and the presence of this roll angle θ causes rotation of the image captured by image sensor 21. Therefore, even if roll angle θ is fixed by positioning pin 13 of lens unit 10, if image sensor 21 itself has a roll angle θ with respect to the optical axis, rotation of the captured image will be caused.

[0031] Therefore, in this embodiment, by using left and right camera modules 1L, 1R in which the relative relationship between the lens unit 10 and the image sensor 21 is fixed in an ideal position without rotation around the optical axis using the manufacturing procedure below, it is possible to easily suppress errors in the parallelism between the left and right optical axes, the optical axis spacing (baseline length L), and the left and right roll angles θL, θR.

[0032] <Procedure for Fixing the Lens Unit 10 to the Adjustment Jig 200> First, the procedure for fixing the lens unit 10 to the adjustment jig 200 for adjusting the camera module will be described with reference to the perspective views of FIGS. 5A to 5C.

[0033] 5A is a perspective view of the adjustment jig 200 and the lens unit 10 before being fixed, as viewed from above, with the arrow in the figure indicating the direction of movement of the lens unit 10. As shown here, the adjustment jig 200 has a roughly U-shaped structure with a pair of protrusions, and has a through-hole 201 formed in a position that is intended to face the reference surface 12 of the lens unit 10. Note that the Cartesian coordinate system in the figure is set so that the X-axis is oriented in the long side direction of the lens unit 10, the Y-axis is oriented in the short side direction of the lens unit 10, and the Z-axis is oriented in the optical axis of the lens unit 10.

[0034] 5B is a perspective view of the lens unit 10 and adjustment jig 200 of FIG. 5A, viewed from below. As shown here, a contact surface 202, a positioning V-groove 203, and a positioning plane 204 are formed on the bottom surface of the adjustment jig 200. The contact surface 202 is a plane formed to surround the lower end of the through-hole 201 and simulating the function of the contact surface 101 of FIG. 4 on the adjustment jig 200, and is formed at a position intended to face the reference surface 12 of the lens unit 10. The positioning V-groove 203 is a groove that simulates the function of the positioning hole 102 of FIG. 4 on the adjustment jig 200, and is formed at a position intended to come into contact with one of the positioning pins 13 of the lens unit 10. The positioning plane 204 is a plane that simulates the function of the positioning elongated hole 103 of FIG. 4 on the adjustment jig 200, and is formed at a position intended to come into contact with the other positioning pin 13 of the lens unit 10.

[0035] FIG. 5C is a perspective view showing a state in which the lens unit 10 is fixed to the adjustment jig 200. As shown in the figure, one of the positioning pins 13 of the lens unit 10 is tangent to two surfaces of the positioning V-groove 203 of the adjustment jig 200, and the other positioning pin 13 is tangent to the positioning flat surface 204. This simulates a state in which the positioning pins 13 of the lens unit 10 are fixed to the positioning holes 102 and the positioning elongated holes 103 of the housing 100, and movement of the lens unit 10 in the X-axis and Y-axis directions is restricted. Furthermore, by applying negative pressure to the through-hole 201 of the adjustment jig 200 to attract the lens unit 10, movement of the lens unit 10 in the Z-axis direction is restricted. In this manner, the lens unit 10 is fixed to the adjustment jig 200. Note that a method of mechanically fixing the lens unit 10 may be used as a method of fixing the lens unit 10 to the adjustment jig 200, in which case the through-hole 201 may be omitted.

[0036] 5A and 5B, when lens unit 10 is attached to adjustment jig 200 from the Y direction, if positioning pin 13 of lens unit 10 interferes with abutment surface 202 of adjustment jig 200, lens unit 10 cannot be attached to adjustment jig 200. Therefore, in this embodiment, lens unit 10 is designed so that the tip of positioning pin 13 is located farther from abutment surface 202 in the optical axis direction when reference surface 12 abuts against abutment surface 202, in other words, so that the tip of positioning pin 13 is lower than reference surface 12 (see FIG. 5A), thereby preventing the above-mentioned interference from occurring.

[0037] <Method for adjusting the relative relationship between the lens unit 10 and the image sensor 21> 6 and 7, an adjustment method called Active Alignment will be described, which adjusts the relative relationship between the lens unit 10 and the image sensor 21 to an ideal position without rotation around the optical axis. This adjustment method simultaneously adjusts the vertical position (focus adjustment direction) and horizontal position (center optical axis position) of the image sensor 21 relative to the lens unit 10, as well as the image plane tilt and roll angle of the lens unit 10.

[0038] 6 shows a central collimator C0 and a peripheral collimator C1 that are installed in the imaging direction of the lens unit 10 in order to perform active alignment, as well as the imaging element board 20 and wiring 30 that are arranged on the back side of the lens unit 10. In FIG. 6, the lens unit 10 is fixed to an adjustment jig 200 (not shown), and the relative relationship between the lens unit 10 and the imaging element board 20 is adjustable.

[0039] Here, the central collimator C0 is a collimator arranged on the object side so as to be coaxial with the optical axis of the lens unit 10. The peripheral collimators C1 are four collimators arranged parallel to the central collimator C0 along the four sides of an imaginary rectangular prism whose central axis is the optical axis of the lens unit 10. Therefore, the peripheral collimators C1 are arranged one by one in the first to fourth quadrants of the XY coordinate system of the lens unit 10 shown in Fig. 6, and each is positioned symmetrically with respect to the X axis and the Y axis. Here, each collimator has, for example, a thin cross reticle, which can be observed at infinity.

[0040] 7 is a diagram showing the procedure for adjusting the position and attitude of the image sensor 21 relative to the lens unit 10, in which R0 and R1 respectively represent the reticle cross images of the central collimator C0 and the peripheral collimator C1 formed on the image sensor 21 via the lens unit 10. Note that, as is obvious from the fact that the peripheral collimators C1 are arranged one each in the first to fourth quadrants of the XY coordinate system of the lens unit 10 in FIG. 6, in the XY coordinate system of the image sensor 21 which roughly coincides with the XY coordinate system of the lens unit 10 even before adjustment, the reticle cross images R1 of the peripheral collimator C1 are formed one each in the first to fourth quadrants.

[0041] As shown in Figure 7(a), when the focus adjustment of the lens unit 10 is completed, the reticle cross image R0 captured through the lens unit 10 is assumed to be shifted from the desired coordinates of the image sensor 21 (for example, if the camera module 1 is designed so that the optical axis is positioned at the center of the image sensor 21, the center coordinates of the image sensor 21).

[0042] Therefore, as shown in FIG. 7(b), the position of the image sensor 21 relative to the lens unit 10 (i.e., the position of the image sensor substrate 20 on which the image sensor 21 is arranged) is adjusted so that the reticle cross image R0 coincides with the desired coordinates of the image sensor 21.

[0043] 7(c), the relative relationship between the lens unit 10 and the image sensor 21 is adjusted to an ideal position with no rotation about the optical axis. Specifically, the rotation angle of the XY coordinate system of the image sensor 21 with respect to the XY coordinate system of the lens unit 10 defined by the peripheral collimator C1 is calculated from the coordinates of the four reticle cross images R1 projected onto the XY coordinate system of the image sensor 21, and the rotation of the image sensor 21 (i.e., the rotation of the image sensor substrate 20) is adjusted so that the roll angle θ of both XY coordinate systems becomes 0.

[0044] After adjusting the position and angle of the image sensor 21 using the steps shown in Figures 7(a) to (c), the lens unit 10 and the image sensor substrate 20 are fixed with adhesive, thereby fixing the relative relationship between the lens unit 10 and the image sensor 21 to an ideal position with no rotation around the optical axis.

[0045] <Summary> As described above, according to the camera device of this embodiment, it is possible to easily suppress errors in the parallelism between the optical axes of the left and right camera modules, the base line length, and the left and right roll angles. [Explanation of symbols]

[0046] 1...camera module, 10...lens unit, 11...lens barrel portion, 12...reference surface, 13...positioning pin, 20...imaging element board, 21...imaging element, 30...wiring, 100...casing, 101...contact surface, 102...positioning hole, 103...positioning elongated hole, 200...adjustment jig, 201...through hole, 202...contact surface, 203...positioning V-groove, 204...positioning flat surface, C0...central collimator, R0...reticle cross image of central collimator, C1...peripheral collimator, R1...reticle cross image of peripheral collimator

Claims

1. A stereo camera in which a left camera module and a right camera module are attached to a highly rigid housing, Each camera module is a lens barrel portion housing a plurality of lenses; a plurality of reference surfaces arranged on the same plane, the reference surfaces being perpendicular to the optical axis of the lens and abutting against an external abutment surface; a pair of positioning pins that fix a center position of the lens or restrict movement in a rotational direction when the reference surface is in contact with the contact surface; The lens unit is an integrally molded resin part. The housing has a plurality of left contact surfaces formed as flat surfaces facing the plurality of reference surfaces of the left camera module and a plurality of right contact surfaces formed as flat surfaces facing the plurality of reference surfaces of the right camera module, which are formed on the same plane; a left positioning hole into which one of the positioning pins of the left camera module is fitted, a left positioning elongated hole into which the other of the positioning pins is fitted, a right positioning hole into which one of the positioning pins of the right camera module is fitted, and a right positioning elongated hole into which the other of the positioning pins is fitted, The left positioning elongated hole is formed long in the direction of a straight line connecting the left positioning hole and the left positioning elongated hole, and the right positioning elongated hole is formed long in the direction of a straight line connecting the right positioning hole and the right positioning elongated hole.

2. The stereo camera of claim 1 A stereo camera, characterized in that the tip of the positioning pin is located at a position farther from the abutment surface in the optical axis direction of the lens when the reference surface abuts against the abutment surface.

Images