Patent Application
20190129128
Joints are described used for mating two components of an apparatus that have been precisely aligned with respect to each other, e.g., based on a six degrees of freedom alignment procedure. For example, the precisely aligned components can be optical components that are part of an optical apparatus with highly sensitive mechanical tolerances.
Conventionally, joining of two components that have been aligned with high precision, often requires use of either (i) high precision parts, or (ii) complex parts with integrated alignment adjustments. The high precision parts need high precision test equipment that comes with calibration management systems that are operated by skilled operators. Because tolerances of such high precision parts are at the edge of machinability, frequent quality issues can occur. For example, the high precision parts are susceptible to handling damage that creates small burrs and other asperities that can ruin the desired quality of the part. Aside from component cost and complexity, the integrated alignment adjustments can have reduced reliability due to stresses locked into the components during fixing of the alignment.
Implementations of a joint described herein are used for mating two components of an apparatus that have been precisely aligned with respect to each other, the disclosed joint including a small number of low cost and low precision parts. Some of the parts of the disclosed joint can have high thermal conductivity and include materials with coefficients of thermal expansion (CTEs) that are well matched with the CTEs of the two components of the apparatus to be joined. In such cases, the disclosed joint, although formed from low cost, low precision parts, will be a high reliability joint.
According to an aspect of the disclosed technologies, an apparatus includes a first component of the apparatus; a second component of the apparatus; and a joint coupling the first component with the second component. Here, the second component has been precisely aligned with the first component. Additionally, the joint includes a first side defining a flat surface; a second side defining sloping faces having different orientations relative to each other; three or more rods disposed between different ones of the sloping faces and the flat surface, where each of the rods forms contact lines between the flat surface and the rod's respective sloping face; and adhesive disposed along the contact lines, the adhesive bonding together the first and second components of the apparatus.
The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In some implementations, the rods can include one or more rods of a first type including a first material having a coefficient of thermal expansion (CTE) that is matched with CTEs of materials of the first and second components of the apparatus; and one or more rods of a second type including a second material having a CTE that is mismatched with CTEs of the of the first and second components of the apparatus. In some cases, the first type rods and the second type rods can be disposed in an alternating manner with respect to the sloping faces. In some cases, the first material can be the same as the materials of the first and second components of the apparatus. In some cases, the first material and the materials of the first and second components of the apparatus can include thermally conductor materials; and the adhesive disposed along the contact lines formed by the first type rods can include thermal conductor adhesive. In some cases, the second material can be transparent to ultraviolet (UV) light; and the adhesive disposed along the contact lines formed by the second type rods can include UV curable adhesive. For example, the second material transparent to UV light can include one or more of fused silica or borosilicate glass.
In some implementations, the rods can include one or more rods of a cylindrical shape having a cylindrical surface, such that an associated pair of contact lines are formed by the cylindrical surface of the cylindrical shaped rod; and one or more rods of a cylindrical sector shape having a cylindrical surface and at least one flat surface, such that one of an associated pair of contact lines is formed by the cylindrical surface of the cylindrical sector shaped rod, and a second one of the associated pair of contact lines is part of a contact strip that is formed by the flat surface of the cylindrical sector shaped rod. In some cases, the flat surface can include more than one flat surface separated channels in the sector shaped rod.
In some implementations, the rods can include hollow tubes. In some implementations, the second side can include a joint base that has a base surface and the sloping faces; and an angle of the sloping faces relative to the base surface is an acute angle. In some cases, the angle of the sloping faces is between 30° and 60°.
In some implementations, the second side of the joint can define three or more sloping faces. In some cases, the three or more sloping faces can be six sloping faces.
In some implementations, the apparatus can be an optical apparatus. In some cases, the first component can include an image sensor; and the second component includes a lens arranged to image a scene on the image sensor. In some cases, the first component can include a laser arranged to illuminate a scene; and the second component includes a lens arranged to image the scene.
Particular aspects of the disclosed technologies can be implemented so as to realize one or more of the following potential advantages. For example, the disclosed joint can achieve very high precision alignment of two mated parts with small locking errors, on the order of about 1-5 microns. Locking errors are shifts from an optimized position, which was obtained by making a series of adjustments, due to stresses generated in the process of fixing the adjustments. Here, the locking errors are small because adhesive lines included in the disclosed joint can be thin, having near zero thickness at each contact line. Thin bond lines minimize locking errors caused by shrinkage of the adhesive during the cure cycle. Such thin adhesive lines render the disclosed joint very reliable, as there is little adhesive to swell due to humidity or expand/shrink over temperature due to the typically large CTE of adhesive.
As another example, the disclosed joint further can improve stability of a mount supporting an imaging sensor because the CTE is matched between the mount, joint and housing of an optical apparatus that includes the imaging sensor. In addition to the disclosed joint having components that are thermally matched and adhesive lines that are thin, symmetry of an arrangement, inside the joint, of the joint components provides additional stability.
As yet another example, the disclosed joint can have high reliability as the joint is stable over environmental changes in temperature, humidity, and mechanical vibration or shock. As yet another example, the thermal conductivity of the disclosed joint can be high, which allows for heat to be drawn away from heat generating components of an optical apparatus, e.g., an imaging sensor. In this manner, a junction temperature of the imaging sensor coupled to the apparatus' housing with the disclosed joint is reduced, which can cause improvement in the lifetime of the imaging sensor and reduction of warm-up time of the optical apparatus.
As yet another example, the disclosed joint uses a small number of components and these joint components can be low precision and low cost. This can cause cost savings in the manufacturing of the joint components as well as in the infrastructure necessary to test, qualify and validate the joint components' quality.
Details of one or more implementations of the disclosed technologies are set forth in the accompanying drawings and the description below. Other features, aspects, descriptions and potential advantages will become apparent from the description, the drawings and the claims.
Certain illustrative aspects of the joints according to the disclosed technologies are described herein in connection with the following description and the accompanying figures. These aspects are, however, indicative of but a few of the various ways in which the principles of the disclosed technologies may be employed and the disclosed technologies are intended to include all such aspects and their equivalents. Other advantages and novel features of the disclosed technologies may become apparent from the following detailed description when considered in conjunction with the figures.
The housing 110 forms a stiff mounting base for supporting and arranging together all of the optical apparatus 100's components. In some implementations, the housing 110 is made, at least in part, from a material that is thermally conductive. An example of such material can be a metal, e.g., Al, or a metal alloy, e.g., brass. Such a housing 110 can dissipate heat generated by the image sensor 140 or by the laser 120. In other implementations, the housing 110 is made, at least in part, from a dielectric material, such as, e.g., plastic, glass, carbon fiber composite or ceramic.
The laser 120 is arranged to illuminate the scene 105 with a laser beam that propagates along a ray R1, in the following manner. The laser 120 incorporates a small radius cylinder lens 125 that fans the laser beam in a plane y′-z′ of a Cartesian reference system (x′, y′, z′) associated with the laser. This fanned beam forms an object plane for the imaging lens 130. The scene 105 illuminated by this object plane will be imaged by the imaging lens 130 in a plane of the image sensor 140 based only on light scattered from the surface of the scene. Since the scattered light is diffused, only a very small fraction of the laser light impinging on the surface of the scene can be collected by the imaging lens 130, especially in the case of smooth (reflective metallic surface of the) scene 105. To maximize light collection, a “fast” large aperture (low F#) imaging lens 130 is employed. This fast imaging lens 130 has a wide cone angle which creates a high sensitivity to defocus.
The above-noted object plane is tilted by an angle α relative to the optical axis of the imaging lens 130, and thus some of the scattered light that propagates along the optical axis of the imaging lens (e.g., along ray R2) creates an image tilted by angle γ relative to the optical axis, in accordance with the Scheimpflug principle. In the example shown in
In this example, the image sensor 140 and the laser 120 each requires very high precision adjustment relative to the imaging lens 130 when mounted in the housing 110, e.g., of order 1 to 10 μm, while the other components can be mounted to the housing based only on their mechanical tolerances, without need for alignment relative to the imaging lens. For instance, the imaging lens 130 can be secured directly to the housing 110. In the case of coupling the image sensor 140 with the imaging lens 130 (via the housing 110), the image sensor is first coupled with a joint base 152 that is part of the joint 150, and then the image sensor is aligned with high precision relative to the imaging lens 130. Once the alignment error between the image sensor 140 and the imaging lens 130 has been sufficiently minimized, the joint base 152 is joined to a flat face of the housing 110 using other components of the joint 150. The joint 150 used to couple the image sensor 140 with the imaging lens 130 is described in detail below in connection with
The joint base 152 includes a structure 160, also referred to as a pedestal, having faces with different orientations relative to each other. In some implementations, the joint base 152 also has a back surface 154 that is flat. Here, the faces of the structure 160 are sloping relative to the flat surface 154. Further, the joint 150 includes three or more rods that are either of a first type, e.g., rods 170a, 170b, 170c, or of a second type, e.g., rods 180a, 180b, 180c, or a mix of rods of both types. The rods are disposed between respective sloping faces of the pedestal 160 and the flat surface 111 of the housing 110 as described below in connection with
The pedestal 160 of the joint base 152 can have three or more sloping faces 162a, 162b, 162c, etc., that are arranged to form a pedestal shaped like a truncated polygonal pyramid. Accordingly, each sloping face of the truncated polygonal pyramid-shaped pedestal 160 is shaped like a trapezoid. The shorter base of each trapezoidal sloping face 162 is equal to or longer than a length of the rods 170, 180, hence it can have a value of about 5, 10, 15 or 20 mm, for instance. In general, the length of the sloping faces 162 is dependent upon a range of the desired adjustability and basic geometry of the joint 150. For example, if the adjustability range is small, the sloping faces 162 could be very short. The height of each trapezoidal sloping face 162 is larger than a diameter (or width) of the rods 170, 180, hence it can have a value of about 2, 5 or 10 mm, or other height values. Further, each face of the truncated polygonal pyramid-shaped pedestal 160 is sloped relative to the back surface 154 by an acute sloping angle θs (as shown in
In some implementations, the pedestal 160 of the joint base 152 can include two or more support elements, e.g., in the form of fences 164a, 164b illustrated in
A length of the rods 170, 180 along the z-axis can have a value of about 5, 20, 15 or 20 mm, or other length values. A radius of curvature of the cylindrical surface 174, 184 of the rods can have a value of about 1, 2.5 or 5 mm, or other radius values. In some implementations, either of the first or second type of rods 170, 180 can be solid material, i.e., can have a solid profile. In other implementations, either of the first or second type of rods 170, 180 can be hollow material, i.e., can have a hollow, tubular profile.
In some implementations, the rods 170, 180 can be made from the same material as the material of the pedestal 160 of the joint base 152 and as the material of the flat surface 111 of the housing 110. In some implementations, the rods 170, 180 can be made from a different material than, but having matching CTE with, a CTE of the material of the pedestal 160 of the joint base 152 and a CTE of the material of the flat surface 111 of the housing 110. In either of these cases, the joint 150 described above in connection with
In some implementations, when materials (e.g., Al) of the pedestal 160 of the joint base 152 and of the material (e.g., Al) of the flat surface 111 of the housing 110 have good thermal conducting properties, good thermal conducting properties also are used at least for material in the adhesive lines 194, 196 (e.g., thermal epoxies). In some cases, the rods 170, 180 also are made from materials (e.g., Al) that have good thermal conducting properties. In either of these cases, the joint 150 described above in connection with
In some implementations, the first type of rods 170 can be made from a material that is transparent to light used for curing the adhesive lines 194a, 194b. For instance, if material included in the adhesive lines 194a, 194b is ultraviolet (UV) curable epoxy, then the first type of rods 170 can be made from one or more of fused silica or borosilicate glass. In this case, the UV curable epoxy lines 194a, 194b can be exposed to UV light delivered from a UV source through the glass rod 170a. In this manner, a mix of first type of rods 170 and second type of rods 170 can be used to form the joint 150, as shown in the example illustrated in
The joint 150 that includes (i) the aluminum joint base 152, (ii) the combination of glass rods 170a, 170b, 170c and UV curable epoxy lines, and (iii) the combination of aluminum quarter round rods 180a, 180b, 180c and thermal epoxy can be fabricated in the following manner. Once the alignment error has been sufficiently minimized, and thus the alignment of the imaging sensor 140 to the image formed by imaging lens 130 is completed, the aluminum joint base 152—that supports the aligned image sensor 140 and that itself is held by an alignment apparatus used to perform the alignment—is ready to be joined to the housing 110. A glass rod, e.g., 170a, is placed between one sloping face, e.g., 162a, of the pedestal 160 and the flat surface 111 of the housing 110—as shown in
Note that the foregoing steps of the process can be completed in 1-2 minutes. Then, a second glass rod 170b is (i) placed between a non-adjacent sloping face, e.g., 162c, of the pedestal 160 and the flat surface 111 of the housing 110, and (ii) bonded in place in the same manner described above in connection with the bonding of the first glass rod 170a. Once the second glass rod is in place, the joint 150 is sufficiently stable to allow the joint base 152 to be released from the aligner apparatus. At this point, the optical apparatus 100, including the partially assembled joint 150, can be turned over. Then, a third and final glass rod 170c is (i) placed between the remaining non-adjacent sloping face, e.g., 162e, of the pedestal 160 and the flat surface 111 of the housing 110, and (ii) bonded in place in the same manner described above in connection with the bonding of the first and second glass rods 170a, 170b.
To finish the joint 150, three aluminum quarter round rods 180a, 180b, 180c are respectively bonded between the remaining unused sloping faces 162b, 162d, 162f of the pedestal 160 and the flat surface 111 of the housing 110. In this example, the aluminum quarter round rods 180a, 180b, 180c are bonded with thermally conducting epoxy. As shown in FIGS. 2B and 5B, for each of the aluminum quarter round rods 180a, 180b, 180c, the geometry of joint 150 will always create a contact line CL and a contact strip CS between the aluminum quarter round rod and respective components mated by the joint. In this manner, for each of the aluminum quarter round rods 180a, 180b, 180c, a narrow thin bond 194 and a large thin bond 196 are created, at least the latter of which having excellent thermal conductivity as well as exceptional reliability properties. In addition, by balancing the CTE of the glass rods with the CTE of the aluminum quarter round rods, a value of an “effective CTE of the joint 150” is closer to values of the CTEs of the components mated by the joint.
In some implementations, the joint 150 is further modified by removing the glass rods 170a, 170b, 170c from the joint after bonding the aluminum quarter round rods 180a, 180b, 180c inside the joint. One reason to remove glass rods 170a, 170b, 170c from the joint 150 would be to potentially reduce the thermal stress induced by leaving them in, as the glass rods have a relatively CTE compared to the aluminum components mated by the joint. These empty locations between respective sloping faces 162a, 162c, 162e and the flat surface 111 of the housing 110 could be either left blank or filed with additional aluminum quarter round rods bonded with thermal epoxy.
As described above in connection with
In the above description, numerous specific details have been set forth in order to provide a thorough understanding of the disclosed technologies. In other instances, well known structures, and processes have not been shown in detail in order to avoid unnecessarily obscuring the disclosed technologies. However, it will be apparent to one of ordinary skill in the art that those specific details disclosed herein need not be used to practice the disclosed technologies and do not represent a limitation on the scope of the disclosed technologies, except as recited in the claims. It is intended that no part of this specification be construed to effect a disavowal of any part of the full scope of the disclosed technologies. Although certain embodiments of the present disclosure have been described, these embodiments likewise are not intended to limit the full scope of the disclosed technologies.
The preceding figures and accompanying description illustrate examples of systems and devices for mating two components of an apparatus to each other securely with alignment accuracy maintained. It will be understood that these methods, systems, and devices are for illustration purposes only. Moreover, the described systems/devices may use additional parts, fewer parts, and/or different parts, as long as the systems/devices remain appropriate. In other words, although this disclosure has been described in terms of certain aspects or implementations and generally associated methods, alterations and permutations of these aspects or implementations will be apparent to those skilled in the art. Accordingly, the above description of examples of implementations does not define or constrain this disclosure. Further implementations are described in the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/028447 | 4/19/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62326656 | Apr 2016 | US |
