Patent Application
20090040631
1. Technical Field
The invention relates to lens barrels of lens modules and, particularly to a lens barrel defining steps in the inner surface thereof and a method for manufacturing the same.
2. Description of the Related Art
In general, a lens module includes a lens barrel and a number of lenses. The lenses are received within the lens barrel. The lens barrel is typically made of plastic materials via injection molding to meet requirements of industry production, e.g., low cost and/or high output. The lens barrel commonly defines a number of steps in the inner surface thereof. These steps are for receiving the lenses and are strictly coaxial with the lens barrel to ensure the lenses received thereby are rigorously coaxial with the lens barrel. One of the challenges of manufacturing such a lens barrel is that due to the thermal properties of plastic materials, the lens barrel contracts and may deform when cooled during the injection molding process. As a result, the coaxality between the lens barrel and the lenses suffers.
Therefore, it is desirable to provide a lens barrel defining steps in the inner surface thereof and a method for manufacturing the same, which can overcome the above mentioned problem.
In an exemplary embodiment, a barrel includes an inner metal barrel, and an outer plastic barrel. The inner metal barrel has a number of concentric annular steps formed in an inner surface thereof. The outer plastic barrel encloses the inner metal barrel therein. The inner metal barrel is integrated with the outer plastic barrel using an insert molding process.
Embodiments of the present lens barrel and method for manufacturing the same will now be described in detail with references to the accompanying drawings.
Referring to
The inner metal barrel 12 is roughly tubular in shape, and can be made from any of the following materials: copper, aluminum, iron, nickel, titanium, steel, carbon steel, stainless steel, and any alloy of copper, aluminum, iron, nickel, titanium. In this embodiment, the inner metal barrel 12 is made from copper alloy.
The steps 122 can be formed by precision machining. In this embodiment, the steps 122 are formed by coaxial machining with computer numerical control (CNC) machine. Coaxiality between the inner metal barrel 12 and the steps 122 can be controlled by the CNC machine. As a result, the coaxality between the lens barrel 10 and the steps 122 is set to be smaller than 5 microns. However, coaxiality between the lens barrel and the steps of plastic lens barrel made by injection molding is approximately 5 to 15 microns. In addition, coaxalities of lens barrels of plastic lens barrel made by plastic injection molding mostly depend on manufacture conditions, such as temperature and/or pressure, and therefore may be greatly different from each other. In all, coaxality between the lens barrel 10 and the steps 122 is more readily controlled and more stable as compared with conventional plastic lens barrels that are made by plastic injection molding. Therefore, coaxality between the lens barrel 10 and lenses (not shown) received thereby is assured.
It should be understood that, the number of the steps 122 is not limited by this embodiment.
The outer plastic barrel 14 can be formed with the inner metal barrel 12 using a variety of methods such as insert molding.
Optionally, the outer surface 126 of the inner metal barrel 12 can be applied with various surface treatments to increase roughness thereof. Thereby, the outer plastic barrel 14 can grasp the inner metal barrel 12 more tightly, avoiding separation therebetween. The outer surface 142 of the outer plastic barrel 14 may be threaded. Thereby, the lens barrel 10 can be coupled to lens holder (not shown) via threads.
Referring to
Operation 22: providing a metal tube 32.
Operation 24: treating the outer surface 126 of the metal tube 32 to increase roughness thereof.
Operation 26: wrapping the metal tube 32 with plastic, thereby forming the outer plastic barrel 14 which wraps the metal tube 32. This can be achieved by insert molding. The outer plastic barrel 14 may include a threaded section 144 on the outer surface 142 thereof.
Operation 28: defining three substantially concentric steps 122 in the inner surface 124 to form the inner metal barrel 12. The steps 122 are substantially coaxial with the inner metal barrel 12. This can be achieved by coaxial machining with CNC machine. Thereby, the lens barrel 10 is obtained.
It will be understood that the above particular embodiments and methods are shown and described by way of illustration only. The principles and the features of the present invention may be employed in various and numerous embodiments thereof without departing from the scope of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200710201339.8 | Aug 2007 | CN | national |
