Patent Application
20080191399
The present application is based on, and claims priority from, Taiwanese Application Number 096202706, filed Feb. 13, 2007, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present invention relates to a high stability planar spring, in particular, a high stability planar spring for voice coil motor. The planar spring according to the invention allows shortened response-time and eliminates the need for an additional damper or additional elasticity.
Due to the fast development of the mobile communication and electronic industry, there is always an urgent demand for more compact and small-sized electronic product. However, machinery and electric equipments has their limits, Micro-electromechanical Systems is currently far from prevalence. Thus, VCM (voice coil motor) is now widely used to provide actuation for electronic products.
The advantages of VCM exist in its small size, low energy consumption, accurate actuation and cheapness. VCM is ideal for short distance movement control, such as the vibration motor for mobile phone, magnetic head/optical pickup head actuator of storage equipment, AF (auto-focus) actuator for a zoom lens of camera, et al. However, compared with the electronic portion of a cell phone, which operates at a speed of millisecond-level, the actuating and restoring speed of VCM is relatively slow. Thus, VCM normally includes an elastic element to accelerate actuating or restoring movement.
A schematic view of a traditional VCM of AF camera is shown in
A traditional planar spring is shown in
Actually, a response-time is the period for a balance to be reach between the Lorentz force applied on the movable part and elasticity of the planar spring. As shown in
In view of the afore-mentioned disadvantages of the prior art, there is a need for enhanced planar spring which overcome the shortcoming of the traditional planar spring of VCM.
One of the objects of the present invention is to provide a planar spring of VCM (voice coil motor) having a high stability. The planar spring facilitates shortening the Response-Time of VCM without any additional higher elasticity of the planar spring and maintaining low energy consumption.
According to the above-mentioned object, the planar spring of the instant invention includes a secured portion for maintaining the shape of the planar spring; a deformation portion extending inwardly from the inner loop of the secured portion; a supporting portion connecting to the secured portion through the deformation portion; a force receiving portion connecting the remote end of the supporting portion; stabilizing portion extending from the conjunction of the supporting portion and the force receiving portion and is positioned between the supporting portion and the secured portion. According to another aspect of the present invention, the secured portion is secured to an outer frame of the VCM, and the force receiving portion is secured to a lens mount.
Still other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description thereof are to be regarded as illustrative in nature, and not as restrictive.
The present invention is illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout and wherein:
The details, structural features and functions of the embodiments of the present invention will be described in details with reference to the accompanying drawings.
As shown in
The deformation portion 22 extends from the inner loop of the secured portion 21. The length and width of the deformation portion 21 are configured depending on demand and the use of the spring. The supporting portion 24 is a rib extending from one end of the deformation portion 22. The length and width of the supporting portion 24 are configured depending on demand and the use of the spring. The far end of the supporting portion 24 crooks and connects to a force-receiving portion 23.
The inner loop of the force-receiving portion 23 connects to the movable part (for example lens mount 15). The inner loop of the force-receiving portion 23 has a plurality of recesses for engaging with the movable part. In addition, in an opposite direction to the connection with force-receiving portion 23, and adjacent to the conjunction point with the supporting portion 23, the stabilizing portion 25 extending from the supporting portion 24. The far end of the stabilizing portion 25 has a protrusion 26. The protrusion 26 is configured to regulate the response performance of the planar spring. Moreover, if the size of the protrusion 26 is bigger than the space defined by the secured portion 21 and the supporting portion 24, the inner loop of the secured portion 21 could be further configured to include a slot 27 for receiving the protrusion 26. According to the current embodiment, there are four stabilizing portions. However, more desirable amount of the stabilizing portions 25, the protrusions 26, supporting portion 24 and deformation portions 22 can be used depending in demand.
In accordance with the above discussion, there are two main method for optimizing the response-time: the first, adding additional damping; the second, using a spring with higher elasticity. However, VCMs are minute motors, and are thin and small so as to particularly meet the demand as being used in cell phone cameras. Thus, a minute size is a prospect in designing VCMs, and additional damping conflicts with this prospect. As for higher elasticity spring, a higher elasticity, in return, would require higher current value to drive the motor, and this will result in higher energy consumption and limit the continuous hours of the battery. Therefore, according to this embodiment, the stabilizing portion 25 can corporate with the protrusion 26, such that, when the VCM operates, the stabilizing portion 25 and the protrusion 26 provide a reversed shock. More specifically, following the inertia rule, when the movable part moves, the stabilizing portion 25 and the protrusion 26 could provide an inertial force that is in an opposite direction to the movement of the movable part. In a transient moment of a response-time, the reverse force, provided by the stabilizing portion 25 and the protrusion 26, could counteracts the inertia of the movable part of the VCM. Thus, as shown in
Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective art and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 096202706 | Feb 2007 | TW | national |
