DE102009027514B4 - Camera module and method for its production - Google Patents

Abstract

Camera module (1), wherein the camera module (1) comprises at least: a carrier device (2), an image sensor (3) which is directly or indirectly received on the carrier device (2), a lens holder (5) which is mounted on the carrier device (3). 2), anda lens (10) having at least one lens (11) received in the lens holder (5) and fixed by means of an adhesive (12) sensitive to UV radiation (16), the lens holder (5) being at least one UV-transparent region (14) is formed, and at least part of the adhesive (12) is provided in the region of the at least one UV-transparent region (14), characterized in that the lens holder (5) has a fastening region (5a) to the Attachment to the support device (2) and a substantially cylindrical holder portion (5b) for receiving the lens (10) and the at least one UV-transparent region (14) as a thin-walled region (14) in the holder portion (5b) is formed where e a second wall thickness in the region of the thin-walled region is smaller than a first wall thickness in the other regions of the holder region (5b) of the lens holder (5), the at least one thin-walled region being in the direction of an upper edge (5e) of the holder region (5b) Image sensor extending pocket (14) is formed.

Description

State of the art

The invention relates to a camera module or imager module, which can be used in particular in a vehicle, as well as a method for its production.

Such camera modules with fixed focus or fixed focal length and object width are used in particular in vehicles or in the automotive sector to detect an external space around the vehicle or even a vehicle interior. Here, an image sensor designed as a semiconductor component is mounted on its circuit carrier or sensor carrier, e.g. a circuit board, mounted together with other components, so that subsequently a lens holder can be placed on the circuit board, which seals the image sensor to the outside and serves to receive the lens. The lens is inserted from above into the lens holder, positioned and fixed.

In order to achieve a permanent mechanical assurance of the distance between the lens and the image sensor, the lens is generally screwed by a thread in the lens holder and fixed in the appropriate axial position. In addition to mechanical connections, such as Threadlockers are also used for welded joints or gluing techniques.

The US 2006/0119730 A1 shows a camera module in which a lens with a lens is screwed from above into a lens holder. Here, the lens is screwed in from above until it reaches the front of a spacer, which is placed on a shoulder of the lens holder. Thus, the focus or the image size is already determined by this geometric design, without a subsequent correction of the focus is possible.

In the case of screw locking, punctual forces can act on the lens, which can thereby impair its optical performance. In laser welding, on the one hand, a relatively high outlay for the system technology and safety is required, and there is also the risk that the punctual application of heat introduces mechanical stresses into the system which can cause a distortion.

A disadvantage of adhesive bonds in general is that the curing of the adhesive takes longer and, depending on the adhesive design is brought about by a temperature step. The handling of the parts between the last optical inspection in the focusing device and also by pressure changes in the heating phase can lead to an uncontrollable defocusing.

In this case, very high optical demands are placed on camera modules, in part because a subsequent change in the focus is no longer possible. Thus, the structure is very sensitive to a change in position of the lens relative to the image sensor. Even a shift in the order of a few 10μm can worsen the image sharpness so that the camera module for high-quality applications can not be used.

The DE 103 42 529 A1 shows a camera assembly, which is particularly suitable for use in a motor vehicle, wherein on the underside of the lens and the top of a lens mount grooves and webs are formed such that concentric guideways are formed. The lens in this case has a conical shape with a hemispherical underside, ie in the form of a spherical cap. The fixing takes place via an adhesive connection, which is formed in a downwardly tapering gap between the lens receptacle formed as part of a housing and the upwardly conically tapering objective. In this case, a UV-sensitive adhesive can be used, which can be irradiated from above through the gap.

The CN 1704786 A shows a corresponding camera module, in which a lens is screwed from above into a lens holder. The assembly is performed by first screwing the lens until a suitable position is reached, then introducing the UV-curing adhesive into a plurality of holes in the peripheral wall of the lens holder and curing with UV radiation through the holes. Subsequently, a thermosetting plastic between a circumferential groove of the lens and the upper edge of the lens holder is introduced for final fixation.

The formation of holes in the lens holder allows this while the supply of adhesive and also the UV irradiation for curing; Such holes or recesses in the wall of the lens holder are manufacturing technology but not unproblematic, since burrs or residues can remain in the production, which break in the subsequent assembly, ie screwing the lens from the top, and thus reach the optical path can. The particles introduced in this way increase the risk of deterioration of the optical properties and of losses in yield, since the particles can significantly impair the image quality due to shading or scattered light. Furthermore, such a two-step bond is relatively expensive. The first bond is made by the UV curing adhesive initially only in marginal areas of the holes between the threads of the lens and the lens holder and therefore acts only in small areas, so that subsequently the additional bonding is carried out by the thermosetting adhesive in the groove provided for this purpose.

The US 2008/0226238 A1 discloses a method for bonding an optical module in which an adhesive is cured by means of UV radiation.

Disclosure of the invention

According to the invention, a fixation of the lens in the lens holder by a UV-sensitive adhesive or adhesive, i. an adhesive that at least partially reacts upon or after UV irradiation. According to the invention, the UV irradiation is effected by a UV-transparent region of the lens holder, i. through the material of the lens holder.

In this case, according to the invention, "UV-transparent" is understood to mean a region of the lens holder which transmits at least a sufficiently large proportion of UV radiation that a reaction of the UV-sensitive adhesive begins, wherein a certain proportion of the UV radiation supplied can be absorbed.

According to an embodiment of the invention, a UV-activatable adhesive or adhesive may be used which, after activation by the UV radiation, subsequently at corresponding thermal conditions, e.g. Room temperature or additional supply of heat, reacted.

The adhesive is preferably introduced between the outside of the lens and the cylindrical inner surface of a holder portion of the lens holder as an adhesive film which is not connected to an outside space, i. not connected to the outside via a window or groove.

The UV-transparent regions may be formed in particular thin-walled. According to the invention, it is hereby recognized that some such thin-walled regions distributed in the circumferential direction on the holder region of the lens holder are sufficient to irradiate the adhesive, so that the further thick-walled regions ensure sufficient stability. Thus, the formation of the thin-walled areas for the stability is straightforward.

The thin-walled regions can thus be e.g. be designed as locally limited pockets between which thicker walled areas are formed. In particular, these thin-walled regions can be formed on the upper side of the lens holder or its cylindrical holder region, so that a thick-walled embodiment with high strength can be provided between and below these thin-walled regions. In such a construction, in particular, the possibility of a cost-effective production of the lens holder as an injection molded part, wherein the lens holder as a substantially cup-shaped or pot-shaped component with wider attachment area for mounting on the circuit board and a still adjoining, substantially cylindrical holder area with at distributed over its top arranged pockets may be formed.

According to the invention, there are some advantages. Thus, the lens holder in a closed sleeve wall, i. be formed without openings, holes or openings and still take place a sufficiently large-scale bonding. Thus, in particular, the problems mentioned at the outset, which can occur during the formation of holes in the sleeve wall, through which particles can get into the optical path, in particular during assembly, do not arise. According to the invention, a closed, dense formation can be achieved in which the introduction of interfering particles and contamination is avoided and yet a large-area bonding can take place. Furthermore, a cost-effective design of the lens holder as a component in injection molding of plastic is possible. Despite the partially thin-walled training high stability is still achieved according to the invention.

By using a UV-activatable adhesive, the high strength of the adhesive bond to the directly cured thin-walled regions, and a subsequent improvement of the adhesive bond can be achieved by reacting the other areas, to which the UV energy could not initially be sufficiently introduced ,

Another advantage is that according to the invention instead of a conventional thread formation between the lens and lens holder and purely axial displacements are possible, for example, with smooth cylindrical surfaces. In this case, for example, a linear adjustment or a linear drive for axial adjustment and positioning can be used. Thus, an additional degree of freedom in the azimuth angle, ie. in the relative rotation of the lens in the plane perpendicular to the optical axis allows, if necessary, to improve the image quality. According to the invention, an in situ positioning and fixation is possible. Since the UV-curing adhesive reacts quickly in the directly irradiated areas, positioning can thus take place by means of, for example, a linear drive, for example also in the case of activated image sensor or image sensor under evaluation of its image signals and when the appropriate positioning by the UV irradiation curing done, which can be checked in situ subsequently in situ, to allow already a final acceptance and possibly rejection as a committee.

The thin-walled regions according to the invention in this case allow a higher power transmission than that in the example CN 1704786 A provided UV adhesive bond in edge areas of holes. In principle, the thin-walled regions can already form a sufficient surface for the formation of high forces, it being possible for subsequent curing to take place by UV activation also in the further, thicker-walled regions.

The position and shape of the UV-transmissive regions can be made variable according to the invention, to allow the integration of one or more UV light sources in the focusing distance and to allow the recording of the UV light sources in a manufacturing process.

list of figures

• 1 shows the structure of a camera module according to the invention in a partially sectioned representation;
• 2 shows the camera holder in perspective view;
• 3 shows a flow chart of the manufacturing method according to the invention.

Description of the embodiments

In 1 is a camera module according to the invention 1 shown in a partially sectioned illustration. On a serving as a carrier device or circuit board circuit board 2 are an image sensor 3 and other components 4 mounted and contacted. The image sensor 3 may be formed in particular as a semiconductor device. As another component 4 may be another integrated circuit, for example, serving as a control device microprocessor 4 , be provided. On the top 2a the circuit board 2 is still a lens holder 5 mounted in the 2 shown in more detail. The lens holder 5 has a lower, widened attachment area 5a and an upwardly adjoining cylindrical holder portion 5b on. The attachment area 5a is in 1 shown cut to the arrangement of the image sensor 3 within this light-tight mounting area 5a to show. At the attachment area 5a are screw receptacles (fastening straps) 6 with holes 7 formed with corresponding holes 8th in the circuit board 2 Align so that screws 9 are passed through it for attachment.

In the holding area 5b is a lens 10 set in the at least one lens not shown here in more detail 11 is included. The setting of the image width b, ie the distance between the lens 11 or - with multiple lenses 11 - the optical reference plane of the plurality of lenses to the sensitive surface of the image sensor 3 along the optical axis A takes place by longitudinal adjustment of the lens 10 in the holder area 5b of the lens holder 5 ,

According to the invention, the position of the lens 10 in the holder area 5b through an adhesive layer 12 Made of UV-curing adhesive. The adhesive layer 12 is in this case completely between the cylindrical outer surface 10a of the lens 10 and the cylindrical inner surface 5c of the holder area 5b educated.

According to the invention for this purpose in the holder area 5b thin-walled areas, in particular thin-walled pockets 14 arranged distributed in the circumferential direction. How out 2 a second wall thickness d2 of the holder area can be seen 5b in the field of bags 14 smaller than a first wall thickness d1 in the other areas. The bags 14 are circumferentially on the holder area 5b distributed; they can be arranged at a height, for example. This can be any bag 14 through a recess from the outside 5d be formed of the holder portion 5b ago, so that the inner surface 5c of the holder area 5b represents a smooth cylindrical surface into which the cylindrical lens 10 can be used appropriately. In 2 is the adhesive layer 12 on the inner surface 5c in the area of a bag 14 located. The second thickness d2 of the pockets 14 is for example in the range less than 0.2 mm, z. B. from 0.1 to 0.15 mm. The first thickness d1 of the holder area 5b can be significantly higher, for example at 0.5 to 1.0 mm. As the holder area 5b not continuous thin-walled, but in the circumferential direction between the pockets 14 and below the pockets 14 thick-walled areas are provided, we the stability of the lens holder 5 through the pockets 14 not impaired.

Here, e.g. high-quality plastics such as LCP or PPS are used, which react very low viscous in the melt and thus also produce such small wall thicknesses process reliable. In this case, different reinforcing materials or reinforcing components in the plastic can be used for further optimization.

Advantageously, the inner surface 5c and the cylindrical outer surface 10a thread-free, in particular cylindrically smooth. Basically, however, is the formation of an internal thread on the inner surface 5c and according to a male thread on the outer surface 10a possible.

In the illustrated design, the entire lens holder 5 be made as an injection molded part of a suitable plastic material, since it represents a substantially pot-shaped component. Also the training of the bags 14 at the upper end or upper edge of the holder area 5b is possible directly by injection molding by the pockets 14 to the top edge 5e of the holder area 5b pass.

The production of the camera module according to the invention from the three modules, ie with the image sensor 3 and optionally other components 4 equipped printed circuit board 2 , furthermore the lens holder 5 and as the third assembly of the lens 10 takes place according to the flowchart of 3 in that, after the start in step St0, the lens holder is subsequently in step St1 5 on the circuit board 2 is mounted, for example, over the holes 7 . 8th and screws 9 such that the optical axis A, the center through the image sensor 3 runs concentrically and centrally through the holder area 5b runs. In step St2, the objective becomes the lens 10 inserted from above and positioned along the optical axis A. Here, the image sensor 3 be turned on, so that its image signals can be evaluated to verify the appropriate focus. When reaching the desired height or position of the lens 10 Next, in step St3, UV light becomes 16 in the radial direction on the thin-walled pockets 14 irradiated, so that part of the UV radiation 16 through the thin-walled pockets 14 up to the adhesive layer 12 and thus the UV adhesive layer 12 directly cured, or, with UVaktivierbarem adhesive 12 by the irradiation with the UV radiation 16 the reaction of the glue 12 is started, which subsequently subsequently reacted by a dual mode of action of heat or possibly even room temperature over a longer time. In principle, the adhesive layer 12 also completely in the circumferential direction on the inner surface 5c are introduced and in the UV irradiation initially only in the area of the pockets 14 cure to ensure first secure positioning and subsequently in the other areas between the pockets 14 cure.

The longitudinal adjustment of the lens 10 in the holder area 5b can be done in the preferred thread-free training, for example by a linear drive in the balancing system. Here, if appropriate, a suitable azimuth orientation, ie angular position of the lens 10 in the lens holder 5 to get voted.

After the UV irradiation and at least partial curing, the correct focusing can subsequently be performed directly in step St4 by the operation of the image sensor 3 be checked.

Claims (11)

Camera module (1), wherein the camera module (1) comprises at least: a carrier device (2), an image sensor (3) which is directly or indirectly received on the carrier device (2), a lens holder (5) which is mounted on the carrier device (3). 2), and a lens (10) with at least one lens (11), which is received in the lens holder (5) and fixed by means of a UV radiation (16) sensitive adhesive (12), wherein on the lens holder ( 5) at least one UV-transparent region (14) is formed, and at least part of the adhesive (12) is provided in the region of the at least one UV-transparent region (14), characterized in that the lens holder (5) has a fastening region (14). 5a) for attachment to the carrier device (2) and a substantially cylindrical holder region (5b) for receiving the objective (10) and the at least one UV-transparent region (14) as a thin-walled region (14) in the holder region (5b) is trained, wherein a second wall thickness in the region of the thin-walled region is smaller than a first wall thickness in the other regions of the holder region (5b) of the lens holder (5), wherein the at least one thin-walled regions are defined as from an upper edge (5e) of the holder region (5b) Direction image sensor extending pocket (14) is formed. Camera module after Claim 1 , characterized in that the UV-sensitive adhesive (12) is formed by UV radiation (16) activatable for subsequent curing. Camera module according to one of the preceding claims, characterized in that the UV radiation (16) sensitive adhesive (12) as an adhesive layer (12) between an outer surface (10a) of the lens (10) and an inner surface (5c) of the lens holder (5 ) is trained. Camera module according to one of the preceding claims, characterized in that a plurality of thin-walled regions (14) distributed in the circumferential direction on the holder portion (5b) are formed and the holder portion (5b) between the thin-walled portions (14) having a first wall thickness (d1) is formed greater than a second wall thickness (d2) of the thin-walled regions (14). Camera module according to one of the preceding claims, characterized in that the lens holder (5) is designed as an injection molded part made of plastic. Camera module according to one of the preceding claims, characterized in that an inner surface (5c) of the holder portion (5b) and an outer surface (10a) of the lens (10) are formed thread-free. Camera module according to one of the preceding claims, characterized in that the carrier device (2) is a circuit carrier or a printed circuit board (2), the lens holder (5) on the upper side of the circuit substrate (2) or the printed circuit board (2) is fastened or screwed and the Image sensor (3) is arranged in a light-tight manner within the lens holder (5). Method for producing a camera module (1), comprising at least the following steps: fixing a lens holder (5) on a carrier device (2) on which an image sensor (3) is accommodated, wherein the lens holder (5) comprises at least one UV-transparent region ( 14), the lens holder (5) having a fastening region (5a) for attachment to the carrier device (2) and a substantially cylindrical holder region (5b) for receiving the objective (10) and the at least one UV-transparent region (14 ) is formed as a thin-walled region (14) in the holder region (5b), wherein a second wall thickness in the region of the thin-walled region is smaller than a first wall thickness in the other regions of the holder region (5b) of the lens holder (5), inserting an objective ( 10) in the lens holder (5) and positioning the lens (10) by axial displacement along an optical axis (A) of the lens holder (5) and the image sensor (3), wherein at one Outside surface (10 a) of the lens (10) and / or an inner surface (5 c) of the lens holder (5) a UV-sensitive adhesive (12) is applied, and fixing the position of the lens (10) by irradiating at least a portion of Adhesive (12) from the outside through the at least one UV-transparent region (14) of the lens holder (5), characterized in that during the positioning of the lens in the lens holder, an evaluation of the image signals of the image sensor (3) and the adjustment of the position in Depending on the evaluation of the image signals of the image sensor (3) takes place and the adhesive (12) after the irradiation with UV radiation by a dual action principle of heat over a longer time subsequently reacted. Method according to Claim 8 , characterized in that after the fixation of the position of the lens (10) in the lens holder (5), an in situ verification of the camera module (1) by evaluation of image signals of the image sensor (3). Method according to one of Claims 8 or 9 , characterized in that the positioning of the lens (10) in the lens holder (5) takes place by an axial displacement without thread rotation. Method according to one of Claims 8 to 10 , characterized in that during the positioning of an adjustment of the azimuth angle of the lens (10) in the lens holder (5).

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