Lens assembly and method for assembling the same

A lens assembly is disclosed, which includes a base and a lens barrel. The base has a front edge, a back edge opposite to the front edge and a passage penetrating the front edge and the back edge. The lens barrel is disposed in the passage and includes a lens and a lens holding member holding the lens, wherein an outer surface of the lens holding member is in contact with an inner wall of the passage, and at least one of the inner wall of the passage and the outer surface of the lens holding member includes a smooth surface, arranged such that a thrust force applied on the lens barrel while assembling the lens assembly causes a sliding movement between the base and the lens barrel on the smooth surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an optical element and a method for assembling the same, in particular relates to a lens assembly that is used to capture image and a method for assembling the same.

2. Description of the Related Art

With a progress of technology, various portable electronic products such as mobile phones, personal digital assistants (PDAs), notebook computers, tablet computers, etc. are generally equipped with a micro camera to facilitate users taking pictures in daily life. With a development trend of continuous improvement in performance and declining in price, the camera function has become a basic function of the portable electronic products.

Generally, a micro camera includes an image sensor and a lens assembly. The image sensor may be a charge coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) image sensor, etc. The lens assembly may include a lens barrel and a base, wherein screw portions are disposed on both of the lens barrel and the base, and the lens barrel and the base are assembled via the screw portions. Through a rotation of the lens barrel, the position of the lens barrel relative to the base can be adjusted so as to project an image onto an imaging plane of the image sensor.

Recently, size reduction is a trend for portable electronic products; however, the screw portions may cause an increase in thickness of the lens assembly which cannot satisfy the demand of portability. Therefore, a need exists for a lens assembly that overcomes the structural issues inherent with the conventional lens assembly found in the art.

BRIEF SUMMARY OF THE INVENTION

In this regard, one objective of the disclosure is to provide a lens assembly with no screw portions, in which a lens barrel of the lens assembly is moved in a sliding manner to adjust a focal length thereof.

In one embodiment, the lens assembly comprises a base and a lens barrel. The base has a front edge, a back edge opposite to the front edge and a passage penetrating the front edge and the back edge. The lens barrel is disposed in the passage and comprises a lens and a lens holding member holding the lens. An outer surface of the lens holding member is in contact with an inner wall of the passage, and at least one of the inner wall of the passage and the outer surface of the lens holding member comprises a smooth surface, arranged such that a thrust force applied on the lens barrel while assembling the lens assembly causes a sliding movement between the base and the lens barrel on the smooth surface.

In the above-mentioned embodiment, the base comprises a protrusion protruding from the inner wall of the passage, and the protrusion has at least one insertion hole penetrated through the protrusion along a direction parallel to a longitudinal axis of the passage.

In the above-mentioned embodiment, the protrusion is circumferentially protruding from the inner wall of the passage to define a through hole which is able to allow light from the lens to pass through.

In the above-mentioned embodiment, the lens has a light emitting surface comprising a first segment and a second segment peripherally surround the first segment, wherein the second segment comprises a flat surface which is aligned with the insertion hole.

In the above-mentioned embodiment, the protrusion is closer to the back edge than the front edge. The inner wall of the passage comprises a smooth surface, and the smooth surface connecting between the front edge and a surface of the protrusion.

In the above-mentioned embodiment, a width of the passage in a direction vertical to a longitudinal axis of the passage is larger or equal to a width of the lens holding member in the direction vertical to a longitudinal axis of the passage.

In the above-mentioned embodiment, the base has at least one groove disposed on the front edge and connected to the passage, and an adhesive is applied in the groove to fix the lens barrel.

In the above-mentioned embodiment, the outer surface of the lens holding member comprises a smooth surface and a recession disposed on the smooth surface.

In the above-mentioned embodiment, the lens holding member comprises a top wall and a peripheral wall extending from the top wall, and the top wall and the peripheral wall cooperatively defining an accommodating space, wherein the lens is disposed in the accommodating space and the peripheral wall.

The disclosure also provides a method for assembling the lens assembly according to any one of the embodiments set forth, the method comprises: providing a base with a passage; placing a lens barrel in the passage of the base; providing a thrust force on the lens barrel to cause a sliding movement between the base and the lens barrel; and fixing the lens barrel in the passage.

In the above-mentioned embodiment, the method further comprises moving the lens barrel to a predetermined position in the passage according to a focal length of a lens of the lens barrel.

Since the lens barrel and the base are connected each other by smooth surface(s) rather than screw portions, the thickness of side walls of the lens barrel and the base can be reduced. Additionally, since the lens barrel can be slid to a predetermined position in the base by directly applying a trust force thereon, instead of by rotating, the assembling time of the lens assembly is further reduced.

DETAILED DESCRIPTION OF THE INVENTION

Several exemplary embodiments of the application are described with reference toFIGS. 1 through 6, which generally relate to the generation of a secret key. It is to be understood that the following disclosure provides various different embodiments as examples for implementing different features of the application. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense.

Referring toFIG. 1, the lens assembly1of the disclosure includes a lens barrel5and a base10, and the lens barrel5includes a lens holding member20and a lens30held by the lens holding member20. While assembly the lens assembly1, the lens barrel5is mounted on the base10, so that a focal length between the lens barrel5and an image sensor (not shown) which is connected to the base10is stably maintained.

The structural features of the lens barrel5and the base10are described in details. The base10has a front edge11and a back edge13opposite to the front edge11. The front edge11and the back edge13of the base10are penetrated by a passage110, and a plurality of grooves130are disposed on the front edge11of the base10and connected to the passage110, respectively. As shown inFIG. 2, each of the grooves130has a first side wall131and a second side wall133, wherein the first side wall131is connected with the front edge11of the base10and the second side wall133is connected between the first side wall131and an inner wall17of the passage110.

The base10includes a protrusion150circumferentially protruding from the inner wall17of the passage110to define a through hole120near the back edge13of the base10, wherein a plurality of insertion holes151penetrates the protrusion150along a direction parallel to a longitudinal axis C of the passage110. In the embodiment, a part of the inner wall17of the passage110connecting between the front edge11of the base10and a surface153of the protrusion150is a smooth circular surface. The advantage of the feature will be described in the description referring toFIGS. 3 and 4.

Referring toFIG. 1, the lens holding member20includes a top wall21and a peripheral wall23extending from the top wall21, and the top wall21and the peripheral wall23cooperatively defining an accommodating space210. An opening230is disposed on a center of the top wall21of the lens holding member20and communicating with the accommodating space210. In the embodiment, an outer surface231of the peripheral wall23is a smooth circular surface.

The lens30has a light incident surface31and a light emitting surface32opposite to the light incident surface31. The light emitting surface32includes a first segment33and a second segment34, wherein the first segment33is aligned with a center35of the light incident surface31, and the second segment34is a flat surface which peripherally surrounds the first segment33.

Referring toFIG. 3, in an exemplary embodiment, while assembling the lens assembly1, the lens30is mounted into the accommodating space210in advanced, wherein the center35of the light incident surface31is aligned with the opening230, and the light emitting surface32is exposed out of the accommodating space210.

Next, the lens barrel5including the lens holding member20and the lens30is mounted into the passage110through the front edge11. Specifically, the lens barrel5is linearly moved in the passage110until the second segment34of the light emitting surface32abuts the surface153of the protrusion150and the second segment34is aligned with the insertion hole151. In the movement of the lens holding member20, the outer surface231of the lens holding member20is in contact with the inner wall17of the passage110. Next, the lens barrel5is applied by a thrust force through a plurality of pins40of a mounting apparatus (not shown) so as to move in a direction X away from the protrusion150to a predetermined position in the passage110according to a focal length of the lens30.

It is noted that, in the embodiment, a width W1of the passage110in a direction X vertical to a longitudinal axis C of the passage110is slightly larger or equal to a width W2of the lens holding member20in the direction X vertical to the longitudinal axis C of the passage110, and both of the inner wall17of the base10and the outer surface231of the lens holding member20are smooth circular surface. Therefore, a sliding movement between the inner wall17of the base10and the outer surface231of the lens holding member20may occurred. Moreover, by the guiding of insertion holes151, the pins40may properly contact with the second segment34of the light emitting surface32. Thus, the fracture of the lens30due to impaction of the pins40in a slant angle can be prevented.

Referring toFIG. 4, after the position of the lens barrel5, an adhesive50is dispensed into the groove130to fix the lens barrel5in place, wherein the adhesive50is disposed between the outer surface231of the lens holding member20and the groove130of the base10. In the next step, as shown inFIG. 5, the adhesive50may be cured by exposure to ultraviolet light (not shown), and the pins40are removed from the insertion holes151, so as to complete the assembling process of the lens assembly1.

It is noted that while the protrusion150circumferentially protrudes from the inner wall17of the passage110in the above-mentioned embodiment, it should not be limited thereto. In some embodiments, the base10includes a plurality of protrusions150protrusions150spaced apart with each other in the same or different distance are respectively protruded from an inner wall17of the passage110, and each of the protrusions150has a insertion hole151to allow the pins40of the mounting apparatus (not shown) passing therethrough. In still some the other embodiments, the insertion hole151is omitted, the pins40of the mounting apparatus (not shown) are directly inserted into the through holes120defined by the protrusion150to abut the lens30.

It is appreciated that the configuration of the inner wall17of the passage110and the configuration of the outer surface231of the lens barrel5may be modified into any suitable configuration according to demands which is compatible with the dimensions of each other. In addition, it is not necessary that both of the inner wall17of the passage110and the outer surface231of the lens barrel5are smooth surface. In some embodiment, at least one of the inner wall of the passage and the outer surface of the lens holding member comprises a smooth surface, the lens holding member20may slide in the passage110.

Referring toFIG. 6, a cross-sectional view of a lens assembly1′ in accordance with the other embodiment is shown inFIG. 6, in which elements similar with that of liquid lens assembly1shown inFIGS. 1-5are provided with the same reference numbers, and the features thereof are not reiterated in the interest of brevity. The lens assembly1′ differs from the lens assembly1in that the side wall23′ of the lens holding member20′ of a lens barrel5′ includes a smooth circular surface233and a recession235disposed on the smooth circular surface233, since the contact area between the inner wall17of the passage110and the smooth circular surface233of the lens barrel5′ is decreased, the friction force produced therebetween due to the sliding movement is decreased and less trust force is necessary to be applied to the lens30to make it move.

In the disclosure, the position of the lens barrel in the base is adjusted in a sliding manner, wherein no screw portion is necessary to be formed between the lens barrel and the base. Thus, a thickness of the base and the lens holding member may be reduced and there may be more accommodation space for lens, especially for a lens applied to a camera having high image quality, in a compactness electrical device.