Lens holder, sensor unit, and image capturing device
The lens holder with flexible displacement portions and struts compensates for thermal expansion, maintaining alignment and image quality in image pickup devices by minimizing focus shift.
Patent Information
- Application Number
- JP2024192722
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-20
- Filing Date
- 2024-11-01
- Publication Date
- 2025-07-02
AI Technical Summary
Image pickup devices face focus shift due to thermal expansion of materials with different coefficients of linear thermal expansion, leading to blurry or distorted images, particularly in environments with significant temperature variations.
A lens holder with a main body and support columns that allow displacement in response to thermal forces, featuring flexible displacement portions and struts to maintain alignment with the sensor unit, compensating for thermal expansion and contraction.
The lens holder maintains accurate alignment and image quality by minimizing focus shift, ensuring consistent performance across temperature changes.
Smart Images
Figure 2025098938000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a lens holder for an optical unit of an image pickup device, a sensor unit for an image pickup device, and an image pickup device including the lens holder or the sensor unit.
Background Art
[0002] An image pickup device faces problems raised by focus shift due to thermal expansion of materials within the device. In particular, when assembling components made of materials with different coefficients of linear thermal expansion (CLTE), the materials may bend due to temperature changes. Thermal expansion can occur, for example, due to temperature changes in the environment of the image pickup device.
[0003] Image pickup devices are commonly used in various applications including surveillance systems and automotive camera systems. These devices rely on an optical unit with lenses that must maintain accurate alignment with respect to the image sensor position in order to capture clear and accurate images. However, the materials used in the construction of the lens holder and other components of the optical unit may undergo thermal expansion or contraction in response to temperature variations. This can lead to focus shift, where the distance between one or more lenses and the image sensor of the optical unit changes, resulting in a change in the focus of the lens and potentially causing blurry or distorted images.
[0004] Focus shift due to thermal expansion is particularly problematic in environments with significant temperature changes. For example, surveillance cameras placed in outdoor environments can be exposed to temperatures that vary with the seasons and diurnal cycles, while cameras within vehicles must operate reliably under a wide range of weather conditions.
[0005] In applications where particularly high safety and peace of mind, as well as clear images, are required, an imaging device with consistent performance, high stability and reliability is needed. Therefore, a lens holder that minimizes the influence of thermal expansion and can maintain the focus of the lens regardless of temperature changes is required.
[0006] U.S. Patent US2020 / 154020A1 discloses a vehicle camera including a lens holder having a lens barrel for housing a lens, a circuit board, and an image sensor disposed on a first side of the circuit board. The base material of the circuit board is attached to a support column extending from a support structure, and this support column is configured to bend radially either toward or away from the longitudinal axis of the lens barrel.
Summary of the Invention
[0007] An object of the present disclosure is to provide a lens holder for compensating for thermal expansion and contraction.
[0008] Another object is to provide a sensor unit for an imaging device for compensating for thermal expansion and contraction.
[0009] A further object is to provide an imaging device with reduced focus shift due to temperature changes.
[0010] To achieve at least one of the above objects and other objects that will become apparent from the following description, according to the present invention, there is provided a lens holder having the features defined in claim 1. Preferred embodiments will become apparent from the dependent claims.
[0011] More specifically, according to a first aspect of the present invention, there is provided a lens holder for an optical unit of an image pickup apparatus. The lens holder has a main body extending in a lens holder plane, is configured to support a lens of the optical unit, and has a lens mount disposed on the main body extending along a longitudinal axis perpendicular to the lens holder plane, and a support column extending from the main body of the lens holder along the longitudinal axis and configured to support a sensor unit aligned with the optical unit. Each support column has a first end adjacent to the main body of the lens holder and a free second end. The first ends of one or more support columns are adjacent to respective displacement portions of the main body of the lens holder, and these displacement portions are configured to displace outside the lens holder plane in response to a thermally induced force acting on the support columns.
[0012] The lens holder may be integrally injection molded, for example, to ensure structural integrity and / or uniformity of material properties. Injection molding enables the creation of specific contours that may include complex features such as displacement portions and / or support columns. The lens holder may be formed as a single continuous piece with displacement portions and / or support columns formed during injection molding. Thus, there is no need to assemble multiple parts, thereby reducing potential alignment problems and further enabling efficient space utilization as there is no need to add additional or separate parts to form the lens holder. In this way, the lens holder may enable a simplified manufacturing process that, for example, leads to cost-effective production.
[0013] Injection molding may be performed with various materials including metals and polymers.
[0014] Each displacement portion may be a flexible connection portion. The displacement portion may refer to a portion configured to move from its original position, for example, by a force induced by thermal expansion. The displacement may be linear (e.g., involving a movement of position) and / or may involve an angle (e.g., involving a rotation).
[0015] The displacement part may be a design element within the lens holder that absorbs and / or compensates for the displacement of the lens holder and / or the sensor unit relative to each other, and / or enables movement or flexibility. In other words, the displacement part may be an area that experiences movement and / or an adaptive element that manages or controls movement within the system. Essentially, the displacement part may be configured to move under specific operating conditions.
[0016] Each support pillar may be a pin or a joint. The support pillar may be, for example, a connecting component configured to couple and / or fixedly attach the lens holder to the sensor unit.
[0017] Thermal-induced stress is the stress applied to a material or structure due to a change in temperature, which may result in thermal expansion or thermal contraction. An increase in temperature may cause the material to expand, while a decrease in temperature may lead to contraction of the material. Such behavior may be quantified by the coefficient of linear thermal expansion (CLTE) and / or the coefficient of thermal expansion (CTE) of the material. In a constrained environment where the material is attached to a rigid body or another material with a different CLTE, thermal changes may induce stress.
[0018] CLTE and CTE are two measures that indicate how a material reacts to temperature changes. CLTE is specific to linear expansion, and CTE can refer to linear expansion, area expansion, or volume expansion. If the CLTE value of a material is known and the type of expansion (linear, area, or volume) to which the CTE value refers is known, the CTE can be calculated, and vice versa.
[0019] Therefore, when the lens holder is coupled to the sensor unit, the lens holder provides compensation for thermal expansion. In this way, the lens holder may be held in a predetermined position or experience only a slight displacement. Therefore, the distance between the lens holder and the sensor unit can be substantially maintained constant regardless of temperature changes.
[0020] When designing the lens holder for a specific implementation or use case, the lens holder may provide adjustable compensation by adjusting the size of the displacement portion and / or by adjusting the size of the strut. In particular, the lens holder has the ability to overcompensate when necessary for a particular application or purpose.
[0021] The lens holder can compensate for thermal expansion in all three spatial dimensions. In particular, the strut may be designed to bend radially towards and / or away from the lens mount and / or the longitudinal axis to facilitate movement within the plane of the lens holder. On the other hand, the displacement portion is configured to displace outside the plane of the lens holder.
[0022] Thereby, the lens holder can maintain accurate alignment and functionality, ensuring that the imaging device comprising the lens holder is not affected by temperature-induced changes, resulting in improved image reliability.
[0023] Each displacement portion is defined by one or more slits.
[0024] The displacement portion may be any suitable flexible connection. The displacement portion may be, for example, a flexible rib disposed on the lens holder.
[0025] The one or more slits may be elongated cuts or openings made or formed in the lens holder. The one or more slits may be configured to affect the behavior of the lens holder during thermal expansion of the lens holder material and / or components coupled to the lens holder.
[0026] The displacement portion may be characterized by one or more slits. The one or more slits defining each displacement portion may impart flexibility or mobility to each displacement portion, enabling it to adapt in response to thermal expansion.
[0027] One or more slits may be arranged to permit the displacement part to bend, flex, stretch, rotate, and / or move in response to thermal expansion. In one example, the displacement part may be defined by two parallel slits that form ribs where, for example, struts may be arranged.
[0028] The arrangement, orientation, and / or geometric characteristics of one or more slits may be adapted to facilitate the desired movement. Thus, the displacement part may provide the adjustments or modifications necessary to maintain the lens holder in a substantially fixed position relative to, for example, a sensor unit during deformation by thermal-induced forces.
[0029] Each displacement part may be defined by a single slit that forms a tongue.
[0030] The tongue may be defined as an elongate flexible member, or a tab or rib. The tongue may be formed integrally with the lens holder. In particular, the tongue may be a movable element that remains attached to the lens holder at one end and the opposite end may move freely in response to thermal-induced forces.
[0031] The single slit may outline the contour of the tongue, for example, to form a U-shaped slit.
[0032] The tongue may bend, flex, stretch, swivel, rotate, and / or move in response to thermal-induced forces acting on a strut adjacent to the displacement part defined by, for example, a single slit. Thus, the tongue may provide flexibility to the displacement part and, as a result, to the lens holder.
[0033] The tongue may have a linear extension. In other words, the tongue may be a straight tongue within the plane of the lens holder. Alternatively, the tongue may be curved or arcuate.
[0034] Thus, the movement of each tongue can be predictably controlled. This provides the ability of the displacement part and / or the lens holder to move in a specific predetermined manner.
[0035] The tongue may include at least two or more tongues extending along each extension axis, and the extension axis intersects, at a common intersection point, the central axis of the region defined by the peripheral portion of the lens mount.
[0036] In other words, two or more tongues may extend along each extension axis that intersects the central axis of the lens holder. In particular, the extension axes of two or more tongues may have a common intersection point on the central axis. The tongue may extend, for example, radially inward from the peripheral portion of the lens holder.
[0037] The common intersection point may be within the region defined by the peripheral portion defined by the lens mount. Alternatively, the common intersection point may be at any location on the central axis of the lens holder, for example, within the body of the lens holder.
[0038] The central axis may be the central axis within the plane of the lens holder. The central axis may be, for example, the axis of symmetry of the lens holder. In particular, the central axis may intersect the longitudinal axis of the lens holder. The central axis may be perpendicular to the longitudinal axis, for example.
[0039] In one example, the extension axes of the tongues may intersect in pairs along the central axis. In particular, the first pair of extension axes of the tongues may form a first intersection point on the central axis, the second pair of extension axes of the tongues may form a second intersection point on the central axis, and so on.
[0040] On the central axis, the extension axis of the first tongue disposed on the first side of the central axis may intersect the extension axis of the second tongue disposed on the second side of the central axis. More specifically, each pair of tongues may constitute two tongues that are symmetrically arranged or mirror images around the central axis of the lens holder.
[0041] The common intersection point may form a point on the central axis that serves as the lever action point, where the resultant force may act, for example, bringing about the lifting and lowering effect of the lens holder when attached to the sensor unit. In other words, the common intersection point may be a pivot point. When the tongue is displaced, the pivot point may act as the central focus for the lifting and lowering of the lens holder. Thus, the common intersection point may be a point where the extension axis of the tongue converges and exerts a force.
[0042] Accordingly, the first and second intersection points on the central axis may act as two pivot points, resulting in providing a dispersed and / or uniform lifting and lowering of the lens holder. The first and second intersection points may be equidistant from the center of the lens holder.
[0043] When the struts are symmetrically positioned around the center of the lens holder, the thermally induced force may act radially from the center of the lens holder, and the lens holder may move up and down along the longitudinal axis. Thereby, for example, when attached to the sensor unit, it provides a controlled movement of the lens holder when it is subject to thermal expansion and / or contraction.
[0044] Each strut may be integrally formed with the body of the lens holder. In other words, the strut may be formed during the injection molding of the lens holder. In particular, each strut may be integrally formed with the displacement portion.
[0045] The strut may protrude or extend from the body of the lens holder such that one or more struts may have a length in the range of 1 to 10 mm.
[0046] In one example, one or more struts are disposed at the tip of each tongue. In other words, the strut may be disposed at the end of the corresponding displacement portion. However, the strut may be disposed at any suitable position of the displacement portion. The strut may be disposed, for example, in the middle portion of one or more displacement portions.
[0047] The struts may be distributed along the peripheral portion of the lens mount. In other words, the struts may be arranged in the vicinity of the lens mount and / or spaced apart around the lens mount. The struts may be circumferentially spaced around the lens mount and / or around the longitudinal axis of the lens holder.
[0048] There may be a plurality of struts. The lens holder may include at least two struts placed at opposing portions of the lens holder, for example, on opposite sides of the central axis. The lens holder may preferably include four struts in order to provide balanced support to the sensor unit.
[0049] The struts may be arranged around the longitudinal axis of the lens holder. The struts may be away from the peripheral portion of the lens holder and / or may be on the inside. Two or more struts may be equidistant from the center of the lens holder, for example, equidistant from the longitudinal axis.
[0050] The struts may form opposing pairs. Each pair of struts may be positioned symmetrically with respect to the central axis of the lens holder. One pair of struts may be arranged closer to each other than another pair of struts, or vice versa. Such a distribution of struts may facilitate balanced support and thermal adaptation within the lens holder.
[0051] The lens holder may be formed of a polymer material.
[0052] The polymer material can be easily molded or injection molded, enabling the implementation of various shapes, designs, and features.
[0053] Since the polymer material can be lightweight, it contributes to reducing the total weight of the imaging device including the lens holder.
[0054] Furthermore, the polymer material may be treated with various coatings, for example, to improve durability.
[0055] The polymer material may be further flexible. Thus, the polymer material may absorb stresses induced, for example, by thermal expansion and / or thermal induced forces without breaking. In particular, the polymer material may deform elastically, i.e., it may bend or flex under stress and return to its original shape and / or position when the stress is removed.
[0056] Thereby, the displacement part of the lens holder may bend or flex in response to a force, for example, a thermal induced force. In particular, the displacement part may bend without breaking and / or without permanently deforming the displacement part or the lens holder.
[0057] According to a second aspect, a sensor unit for an image pickup device is provided. The sensor unit has a main body extending in the sensor unit plane. The main body of the sensor unit includes a sensor unit displacement part configured to be attached to the free end of a support of the lens holder and to displace out of the sensor unit plane in response to a thermal induced force acting on the support, and each sensor unit displacement part is defined by one or more slits.
[0058] The second aspect generally presents the same or similar advantages as the first aspect. In particular, the features and advantages of the displacement part of the lens holder may be shared with the sensor unit displacement part.
[0059] Thermal expansion and / or thermal induced forces may deform the sensor unit, for example, when the sensor unit is attached to the lens holder.
[0060] The sensor unit, more specifically the sensor unit displacement part, may be adhesively attached to the free end of the support of the lens holder. Alternatively, the sensor unit may include a support corresponding to the support of the first aspect, for example.
[0061] The sensor unit may include an image sensor. The image sensor may be an array of photosensitive elements such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) sensor integrated on a printed circuit board (PCB). The image sensor may capture light through a lens to form an image. The sensor unit may include additional features such as an integrated circuit. The sensor unit may be adapted to acquire images intended to form a video sequence.
[0062] According to a third aspect, there is provided an image capturing device including a sensor unit having an image sensor, and an optical unit including a lens holder according to the first aspect and a lens supported by the lens holder. The image capturing device may be a surveillance video camera.
[0063] Alternatively, the image capturing device includes a sensor unit according to the second aspect having an image sensor, a lens holder, and an optical unit including a lens supported by the lens holder. The lens holder has a support column extending from the main body of the lens holder along a longitudinal axis perpendicular to the surface of the sensor unit and configured to support the sensor unit. Each support column has a first end adjacent to the main body of the lens holder and a free second end.
[0064] The third aspect may generally present the same or similar advantages as the first and second aspects.
[0065] The displacement portion may enable relative movement between the optical unit and the image sensor when the temperature of the environment, the optical unit, and / or the image sensor changes. Thereby, focus shift can be canceled. In particular, the displacement portion may bend along the longitudinal axis, i.e., the optical axis of the image capturing device, such that the distance between the sensor unit and the optical unit is kept substantially constant. Specifically, according to the third aspect, focus shift can be eliminated or at least reduced.
[0066] This provides compensation for focus shift caused by thermal expansion along the longitudinal axis in the image pickup device. Therefore, the displacement unit can maintain a constant distance (with only movement on the order of μm) between the sensor unit and the optical unit regardless of temperature changes.
[0067] The displacement unit of the image pickup device may further overcompensate the displacement as needed, providing further versatility.
[0068] The sensor unit may be coupled to the free second ends of the respective struts of the lens holder. The sensor unit may be coupled to the free second ends of the respective struts via an adhesive or a fastener. In particular, when the displacement unit is disposed on the sensor unit, the free second ends of the respective struts may be coupled to the respective sensor unit displacement parts.
[0069] This enables the displacement part of the sensor unit or the lens holder to compensate for thermal expansion in all three spatial dimensions.
[0070] Compensation for thermal expansion in all three spatial dimensions can be provided by the displacement part providing bending along the longitudinal axis and the struts providing radial bending, i.e., bending of the lens holder surface, towards or away from the longitudinal axis. This ensures that the performance of the image pickup device is maintained without being affected by temperature-induced changes. As a result, image quality and imaging reliability are improved.
[0071] The struts of the lens holder may support the sensor unit. Alternatively, the struts may support the lens holder attached to the sensor unit. In one example, four struts may be provided to provide balanced support.
[0072] The sensor unit may further include a circuit board for processing signals from the image sensor.
[0073] In other words, the sensor unit may include an integrated electronic system that interprets the raw data captured by the image sensor and converts it into a different format.
[0074] The circuit board for processing the signals may be, for example, a PCB. The PCB may enable a compact integration of the circuit and the image sensor.
[0075] The lens may be configured to focus light onto the image sensor. In other words, the lens may direct and / or aim the incident light onto the surface of the image sensor.
[0076] The sensor unit may have a first coefficient of thermal expansion, and the lens holder may have a second coefficient of thermal expansion.
[0077] In other words, the sensor unit may have a first CLTE, and the lens holder may have a second CLTE. In particular, the first CLTE may be smaller than the second CLTE. Thus, the displacement part and / or the strut may bend in response to temperature fluctuations, ensuring that the sensor unit or the PCB does not displace with respect to the lens of the optical unit. In particular, due to the difference in CLTE, the strut may bend radially and the displacement part may bend longitudinally.
[0078] The sensor unit may include, for example, a copper layer, and the lens holder may be made of a polymer material.
[0079] When the sensor unit is attached to the lens holder, the materials with their respective intrinsic CLTEs may each have the potential for thermal changes to induce stress. For example, when the temperature rises and the material is constrained, tensile stress may be applied, potentially causing displacement or misalignment. Similarly, a decrease in temperature may cause compressive stress and promote displacement in the opposite direction.
[0080] Thus, for example, at low temperatures below room temperature or below -20 degrees, the lens holder can shrink more than the sensor unit (especially more than the PCB), bending the struts radially inwards towards the longitudinal axis of the lens holder and bending the displacement part from the lens holder surface towards the sensor unit.
[0081] Conversely, for example, at high temperatures above room temperature or above 50 degrees, the lens holder can expand more than the sensor unit. Thus, the struts can bend outwards from the longitudinal axis of the lens holder and the displacement part can bend outwards from the lens holder surface away from the sensor unit.
[0082] The displacement part of the body of the lens holder or of the sensor unit may allow relative movement between the optical unit and the sensor unit in a direction along the longitudinal axis in order to cancel out the focus shift caused by the difference between the first and second coefficients of thermal expansion.
[0083] In other words, the relative movement can compensate for the difference in thermal expansion of the materials of the sensor unit and the optical unit.
[0084] In general, all terms used in the claims should be construed according to their ordinary meaning in the technical field, unless explicitly defined herein. All references to "A / An / the [element, apparatus, component, means, step, etc.]" should be construed openly as referring to at least one example of the aforementioned element, apparatus, component, means, step, etc., unless explicitly stated otherwise.
[0085] The above and additional objects, features and advantages of the present invention will be better understood from the following illustrative and non-limiting detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, like elements are denoted by the same reference numerals.
Brief Description of the Drawings
[0086]
Figure 1
Figure 2
Figure 3A
Figure 3B
Figure 4A
Figure 4B
Figure 5A
Figure 5B
Figure 6
Best Mode for Carrying Out the Invention
[0087] The present invention will be more fully described below with reference to the accompanying drawings showing presently preferred embodiments of the invention. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided for thoroughness and completeness and to fully convey the scope of the invention to those skilled in the art.
[0088] FIG. 1 shows a lens holder 100 for an optical unit of an image pickup device (see FIG. 6). The lens holder 100 has a main body 110, for example made of a polymer material, extending within the lens holder plane.
[0089] In FIG. 1, the lens holder 100 includes a lens mount 120 disposed on the main body 110. The lens mount 120 is configured to support a lens of the optical unit, and the support columns 132 are configured to support a sensor unit aligned with the optical unit. The support columns 132 are here distributed along the peripheral edge of the lens mount 120.
[0090] More specifically, the struts 132 are disposed in the displacement portions 130. In particular, struts 132 are provided at the ends of each displacement portion 130. However, one or more struts 132 may be disposed in the displacement portions 130.
[0091] Each displacement portion 130 is defined by a single U-shaped slit 134 that forms a tongue 135 with a linear extension along the extension axis 136. However, the slit 134 and the displacement portion 130 may take any suitable shape. For example, the slit may define a curved tongue or an arcuate tongue. This makes it possible to increase the length of each tongue without increasing the radial expansion of the displacement portion. As a result, a displacement portion having a curved or arcuate tongue can facilitate adaptation to relatively large thermally induced movements in a lens holder having a relatively compact design.
[0092] The slit 134 can displace the displacement portion 130 out of the lens holder surface. In other words, the displacement portion 130 may be configured to move or bend in a direction orthogonal to the lens holder surface.
[0093] The extension axes 136 have a common intersection 138. Here, the intersection 138 is located within the region defined by the peripheral portion of the lens mount 120, specifically at the center of the lens holder 100. However, it is understood that the common intersection 138 may be anywhere within the lens holder surface. The intersection 138 may be, for example, near the peripheral portion of the lens mount 120.
[0094] In FIG. 1, any extension axis 136 may represent the central axis 140 of the lens holder 100. The central axis 140 of the lens holder 100 may be any axis within the lens holder surface that intersects the center point of the lens holder 100. Here, the center point of the lens holder 100 coincides with the intersection 138.
[0095] The lens holder 100 may, for example, have a width of 60 to 90 mm, the displacement portion 130 (i.e., the tongue 135) may have a length of 10 to 20 mm, and the support pillar may have a length of 1 to 10 mm. The width of the lens holder may be about 75 mm, the length of the displacement portion may be about 15 mm, and the length of the support pillar may be about 5 mm.
[0096] FIG. 2 shows a lens holder 100 similar to that described in connection with FIG. 1, where the lens holder 100 includes an alternative displacement portion 130.
[0097] Each displacement portion 130 is defined by two slits 134. However, it is understood that one or more slits 134 may define one or more displacement portions 134. The plurality of slits 134 may, for example, form perforations configured to break in response to a thermally induced force to define the displacement portion 130.
[0098] FIG. 2 further shows a first end of each support pillar 132 adjacent to each displacement portion 130 at the central portion of each displacement portion 132. However, one or more support pillars 132 may be joined to each displacement portion 130 at any suitable location.
[0099] The support pillar 132 extends from the main body 110 of the lens holder 100 along the longitudinal axis 122. Specifically, the support pillar 132 protrudes from the displacement portion 130. In particular, the first end of each support pillar 132 is adjacent to the main body 110 of the lens holder 100, and the second end of each support pillar 132 is a free second end.
[0100] The displacement portion 130 is configured to displace in response to a thermally induced force acting on the support pillar 132 when the support pillar 132 is fixed at each free end. The displacement portion 130 may, for example, rotate and / or displace from the lens holder surface.
[0101] FIG. 3A shows a lens holder 100 similar to that of FIG. 1.
[0102] Here, the lens holder 100 has four displacement portions 130 (forming tongues 135), each having a corresponding extension axis 136. The extension axes 136 pair up and intersect the central axis 140 at common intersection points 138a, 138b. In particular, the extension axes 136 of the first and second displacement portions 130 intersect the central axis 140 at the first intersection point 138a, and the extension axes 136 of the third and fourth displacement portions 130 intersect the central axis at the second intersection point 138b. Here, the first intersection point 138a and the second intersection point 138b are located within a region defined by the peripheral portion of the lens mount 120, but the intersection points 138a, 138b may be located anywhere within a region defined by the peripheral portion of the lens holder 100.
[0103] In this embodiment, the displacement portions 130 are symmetrically arranged about the central axis 140. Specifically, the displacement portions 130 are also symmetrically arranged about a second central axis orthogonal to the central axis 140 and within the plane of the lens holder.
[0104] FIG. 3B shows one of the displacement portions 130, for example, the displacement portion 130 of FIG. 3A.
[0105] The displacement portion 130 is defined by a slit 134 that forms the tongue 135. At the end of the tongue 135, a support column 132 is arranged. The support column 132 is in contact with the tongue 135 at a right angle, but the support column 132 may be adjacent to the tongue 135 at any suitable angle. The tongue 135 and the support column 132 are integrally formed with the main body 110 of the lens holder. However, alternatively, the support column 132 may be attached or coupled to the main body 110, for example.
[0106] The tongue 135 extends in the direction towards the lens mount 120, while the support column 132 extends away from the lens holder main body 110 in a direction opposite to the extension of the lens mount 120.
[0107] FIGS. 4A and 4B show an image pickup device. FIG. 4A is an exploded view of the image pickup device 200, and FIG. 4B shows a cross-section of the image pickup device 200.
[0108] The imaging device 200 includes a sensor unit 202 having a circuit board 230 and an image sensor 220 having an optional filter component 210. The imaging device 200 further includes an optical unit having a lens holder 100 according to any one of FIGS. 1 to 3, for example.
[0109] The filter component 210 may be, for example, an IR filter made of glass for the image sensor 220. The circuit board 230 may be a PCB.
[0110] The lens mount 120 extends along a longitudinal axis 122 perpendicular to the extension of the lens holder body 110 (i.e., perpendicular to the lens holder surface). The longitudinal axis 122 may coincide with the optical axis of the imaging device 200.
[0111] In FIG. 4B, the sensor unit 202 is coupled to the free second ends of the respective struts 132 of the lens holder 100. Specifically, the struts 132 of the lens holder 130 are coupled to the circuit board 230. The struts 132 are coupled to the sensor unit 202 at a right angle, but the struts 132 may be coupled to the sensor unit 202 at any suitable angle.
[0112] The struts 132 may be coupled to the sensor unit 202 by a light-curing adhesive such as, for example, an adhesive and / or a UV adhesive.
[0113] Although not shown, it is understood that the displacement portion according to any one of FIGS. 1 to 4 may be mounted on the circuit board of the sensor unit, for example, the sensor unit for the imaging device. In particular, the sensor unit may have a body extending within the sensor unit plane, and the body includes a sensor unit displacement portion configured to be attached to the free end of the strut of the lens holder. The sensor unit displacement portion may be further configured to displace out of the sensor unit plane in response to a thermally induced force acting on the strut.
[0114] Such a sensor unit may be implemented in an imaging device including, for example, a lens and a lens holder having a support pillar extending from the body of the lens holder along a longitudinal axis perpendicular to the sensor unit surface and configured to support the sensor unit. Each support pillar may have a first end adjacent to the body of the lens holder and a free second end.
[0115] FIGS. 5A and 5B are cross-sectional views of the imaging device 200. Here, the sensor unit 202 has a first coefficient of thermal expansion (i.e., the first CLTE), and the lens holder 100 has a second coefficient of thermal expansion (i.e., the second CLTE). Further, the image sensor 220 and the circuit board 230 of the sensor unit 202 have different CLTEs.
[0116] The displacement portion 130 of the lens holder 100 allows the lens holder 100 and the sensor unit 202 to move relative to each other in a direction along the longitudinal axis 122, and cancels out the focus shift caused by the difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion, which results in different levels of material change (expansion or contraction) when the temperature of the material changes.
[0117] In particular, the distance 240 between the lens holder 100 and the image sensor 220 of the sensor unit 202 is kept substantially constant. Specifically, the change in the distance 240 between the lens holder 100 and the image sensor 220 may be less than 10 μm, for example, 0 μm.
[0118] In other words, the distance 240 between the lens holder 100 and the image sensor 220 is an increasing distance (i.e., focus shift) in the direction along the longitudinal axis 122. The distance 240 may more specifically be the distance between the image sensor 220 and a lens disposed within the lens holder 100, for example, the lens disposed closest to the image sensor 220.
[0119] In FIG. 5A, the imaging device 200 is exposed to a warm environment, for example, higher than room temperature and / or higher than the temperature at which the imaging device 200 is calibrated.
[0120] The sensor unit 202 bends due to the thermal expansion of the sensor unit material, and the circuit board 230 protrudes away from the lens holder 100 (the deformation is enlarged for illustrative purposes). Specifically, the image sensor 220 attached to the circuit board 230 bends the circuit board 230 due to the difference in the CLTE between the image sensor 220 and the circuit board 230. Also, the lens holder 100 expands more than the circuit board 230 during heating due to the difference in CLTE.
[0121] As a result, the struts 132 and the displacement portion 130 bend. In particular, the lens holder 100 essentially has a tendency to move away from the sensor unit 202 during heating. However, the displacement of the displacement portion 130 outside the lens holder surface in the direction away from the sensor unit 202 substantially cancels or neutralizes the bending.
[0122] In FIG. 5A, the struts 132 extend in a direction parallel to the longitudinal axis 122. However, in a warm environment, the struts 132 may bend such that the end of the strut 132 adjacent to the displacement portion 130 is further away from the center of the lens holder 100 than the end of the strut 132 coupled to the sensor unit 202.
[0123] In FIG. 5B, the image capturing device 200 is exposed to a low temperature environment, for example, lower than room temperature and / or lower than the temperature at which the image capturing device 200 is calibrated.
[0124] The sensor unit 202 bends due to the thermal contraction of the sensor unit material, and the circuit board 230 protrudes toward the lens holder 100 (the deformation is enlarged for illustrative purposes). In particular, the lens holder 100 contracts more than the circuit board 230 during cooling due to the difference in CLTE.
[0125] The lens holder 100 essentially has a tendency to move towards the sensor unit 202 during cooling. However, the displacement portion 130 displaces out of the lens holder surface in the direction towards the sensor unit 202, whereby the bending is substantially canceled or neutralized.
[0126] In FIG. 5B, the support column 132 is bent such that the end of the support column 132 adjacent to the displacement portion 130 is closer to the center of the lens holder 100 than the end of the support column 132 coupled to the sensor unit 202.
[0127] FIG. 6 shows the imaging device 200 according to FIGS. 4 and 5, further including a lens barrel 250 supported by the lens holder 100.
[0128] The lens barrel 250 is configured to collect light onto an image sensor 220 (not shown). The lens barrel 250 may include one or more lenses such as, for example, a flat lens, a convex lens, and / or a concave lens.
[0129] The displacement portion 130 may be displaced such that the distance 240 between the image sensor 220 and the lens barrel 250 remains substantially constant while being exposed to temperature changes.
[0130] It will be understood that the present invention is not limited to the disclosed embodiments. Accordingly, within the scope of the present invention exclusively defined by the appended claims, some modifications and variations are conceivable.
Claims
1. 1. A lens holder for an optical unit of an image capturing device having a body extending in a lens holder plane, a lens mount disposed on the body, the lens mount configured to support a lens of the optical unit and extending along a longitudinal axis perpendicular to the lens holder surface; a post extending from the body of the lens holder along the longitudinal axis and configured to support a sensor unit aligned with the optical unit; Each post has a first end adjacent the body of the lens holder and a free second end; the first ends of one or more of the posts are adjacent respective displacement portions of the body of the lens holder, the displacement portions being configured to be displaced out of the lens holder plane in response to a thermally induced force acting on the posts; Each displacement is defined by one or more slits.
2. 2. The lens holder of claim 1, wherein each displacement is defined by a single slit forming a tongue.
3. The lens holder of claim 2 , wherein the tongue has a linear extension.
4. 3. The lens holder of claim 2, wherein the tongue comprises at least two or more tongues extending along respective extension axes, the extension axes intersecting a central axis of an area defined by a periphery of the lens mount at a common intersection point.
5. The lens holder of claim 1 , wherein each post is integrally formed with the body of the lens holder.
6. The lens holder of claim 1 , wherein the posts are distributed along a periphery of the lens mount.
7. The lens holder of claim 1 , wherein the lens holder is formed from a polymeric material.
8. A sensor unit for an image capture device, the sensor unit having a body extending into a sensor unit plane, the body comprises a sensor unit displacement portion configured to be attached to a free end of a support post of a lens holder and configured to be displaced out of the sensor unit plane in response to a thermally induced force acting on the support post; A sensor unit, wherein each sensor unit displacement portion is defined by one or more slits.
9. a sensor unit including an image sensor; An optical unit, A lens holder according to claim 1; and an optical unit including a lens supported by the lens holder. or A sensor unit according to claim 8, comprising an image sensor; An optical unit, a lens holder having posts extending from a body of the lens holder along a longitudinal axis perpendicular to a face of a sensor unit and configured to support the sensor unit, each post having a first end adjacent the body of the lens holder and a free second end; and an optical unit including a lens supported by the lens holder.
10. The image capture device of claim 9 , wherein the sensor unit is coupled to the free second end of each post of the lens holder.
11. The image capturing device according to claim 9 , wherein the sensor unit further comprises a circuit board for processing a signal from the image sensor.
12. The image capture device of claim 9 , wherein the lens is configured to focus light onto the image sensor.
13. The image capture device of claim 9 , wherein the sensor unit has a first coefficient of thermal expansion and the lens holder has a second coefficient of thermal expansion.
14. The image capturing device of claim 13, wherein the displacement portion of the body of the lens holder or the displacement portion of the sensor unit enables relative movement of the optical unit and the sensor unit in a direction along the longitudinal axis to counteract focus shifts caused by a difference between the first thermal expansion coefficient and the second thermal expansion coefficient.