BACKGROUND

Field of the Invention

The invention refers to a tri-axis close-loop feedback controlling module for electromagnetic lens driving device, which employs a 6-pin Hall element to allow the electromagnetic lens driving device to control the focusing operations of the auto-focus module along the Z-axis based on a control signal generated according to the X-and-Y axial positions of the auto-focus module, so as to achieve the functions of tri-axis close-loop feedback control.

Description of the Related Art

Digital photography technology has been widely applied to most of the portable electronic devices such as the cellular phones. Various miniaturized techniques in the lens module are involved to make all these applications possible; in particular, the voice coil motor (VCM) technique. The VCM introduces a combination of coiled magnets and spring plates to drive a lens to move back and forth along a photo axis for image-capturing, so as to perform auto-zooming and/or auto-focusing of the lens module. Further, in this trend of demanding for devices capable of high-level photographing functions, photographic quality and various camera functions such as thousand pixels, anti-hand shake ability and so on are equipped to distinguish high-end camera from cost-down level. However, in an optical system composed of an optic lens module, such as a camera system or a video recorder system, hand shake or some external situations usually occur to alter optical path so as to degrade the imaging upon the image-compensation module and further to obscure the formation of the images. A conventional resort to resolve this problem is to introduce a further compensation mechanism for overcoming possible shaking during the imaging. Such a compensation mechanism can be either digital or optical. State of the art digital compensation mechanism is to analyze and process the digital imaging data capturing by the image-compensation module, so as to obtain a clearer digital image. Such a mechanism is also usually called as a digital image stabilization (DIS) mechanism. On the other hand, the optical compensation mechanism, usually called as an optical image stabilization (OIS) mechanism, is to add a shake-compensation module upon the lens module or the image-compensation module.

However, conventional technologies usually employ two different and yet independent control circuitries for the feedback circuits of the auto-focus module and the OIS module in the same camera device. That means, one control circuitry is used for receiving feedback signals of the auto-focus module and also controlling the auto-focus module based on the feedback signals, while another control circuitry is used for controlling the OIS module based on the feedback signals of the OIS module. More particularly, in the conventional technologies, a feedback circuit is individually furnished for detecting and generating a feedback signal according to the position and movement of the lens along its optical path (usually also called as the Z-axis), and thus the auto-focus module can control and drive the lens to move along the Z-axis according to the feedback signal so as to conduct auto-focusing operations; in the other hand, another feedback circuit is individually furnished for detecting and generating another feedback signal according to the position and movement of the lens along a horizontal plane perpendicular to the optical path (usually also called as the X-Y axial plane), and thus the OIS module can control and drive the lens to move along the X-Y axes according to said another feedback signal so as to conduct OIS operations. In the conventional technologies, the auto-focus module cannot receive any feedback signals from the OIS module when performing the Z-axial auto-focusing operations. However, when the OIS module is performing the OIS operations in order to compensate the biased position of the lens caused by shakings, the OIS module will move the X and Y axial positions of the lens, and thus the precise focusing position (Z-axial position) of the lens will also be changed accordingly. Which means, when the OIS module is performing the OIS operations, the auto-focus module is also required to perform and adjust its auto-focusing operations continuously. Unfortunately, because conventional technologies use two different and independent control and feedback circuits for the auto-focus module and OIS module to detect and control the movements of lens in the Z-axis and X-Y axes respectively, thus the responding and interacting speeds of the auto-focus module is relatively slower and delayed, which will cause delayed focusing operations when shakings occur. In addition, because the entire lens module (including lens and auto-focus module) is movable horizontally relative to the OIS module, the circuitry design is very difficult for conventional technologies if someone try to integrate the feedback circuit of the auto-focus module with the feedback circuit of the OIS module into one single circuitry.

SUMMARY

Accordingly, it is the primary object of the present invention to provide a tri-axis close-loop feedback controlling module for electromagnetic lens driving device which comprises a 6-pin Hall element. Two pins of the 6-pin Hall element are coupled to the auto-focus module for providing a current to the auto-focus module in order to drive the auto-focus module to conduct the auto-focusing operations along the X-axis; while other four pins thereof are coupled to a control unit. The control unit can detect the signals generated by the OIS module to obtain the X-Y axial positions of the auto-focus module relative to the OIS module, so as to generate a control signal according to the X-Y axial position of the auto-focus module, and then send the control signal to the 6-pin Hall element. Therefore, the 6-pin Hall element not only can provide its own feedback controlling function according to the Z-axial position of lens, but also can accept the control signal from the control unit and then providing the current for driving the auto-focus module based on the control signal from the control unit, so as to achieve the goal of tri-axis close-loop feedback controlling for the electromagnetic lens driving device.

Another object of the present invention is to provide a tri-axis close-loop feedback controlling module for electromagnetic lens driving device, which comprises a novel electric coupling structure to couple the six pins of the 6-pin Hall element with the circuitries of both the auto-focus module and the OIS module that are movable relative to each other, such that the goal of tri-axis close-loop feedback controlling for the electromagnetic lens driving device can be achieved.

In order to achieve aforementioned objects, the present invention discloses a tri-axis close-loop feedback controlling module for electromagnetic lens driving device, which comprises:

a lens holder for holding a lens;

a movable frame for receiving the lens holder in such a manner that the lens holder is movable relative to the movable frame along a Z-axis direction;

an electromagnetic driving module, furnished between the movable frame and the lens holder for driving the lens holder to move within the movable frame along the Z-axis direction;

an optical image stabilization (OIS) module for driving the movable frame together with the lens holder to perform bi-directional movements along a X-axis direction and a Y-axis direction; wherein the X-axis, Y-axis and Z-axis are perpendicular to each other;

a control unit, coupled to the OIS module; the control unit being able to detect and control operations of the OIS module so as to generate a control signal according to the operations of the OIS module; and

a Hall element having at least six pins; wherein, two of the at least six pins are coupled with the electromagnetic driving module for supplying a current to the electromagnetic driving module in order to control operations of the electromagnetic driving module; other four of the at least six pins are coupled with the control unit for receiving the control signal from the control unit in order to control the current supplied to the electromagnetic driving module based on the control signal, so as to achieve the function of tri-axis close-loop feedback controlling the electromagnetic driving module.

In a preferred embodiment, the tri-axis close-loop feedback controlling module for electromagnetic lens driving device further comprises:

a first circuit board; the control unit being furnished on the first circuit board and coupled with the OIS module; and

an electric coupling structure; the Hall element being coupled with the electromagnetic driving module and the control unit be means of the electric coupling structure;

wherein, the electric coupling structure comprises a first spring plate located at one side of the lens holder along the Z-axis direction; the first spring plate comprises at least four independent and separated first spring members; each one of these first spring members comprises a first inner rim for flexibly retaining a top position of the lens holder along the Z-axis direction and a first contact which is connected with one suspension wire; each one of the suspension wires extends from the first spring members toward the first circuit board and couples to the control unit; the Hall element is coupled with the four first spring members and the electromagnetic driving module, and can receive a control signal from the control unit in order to control and adjust a current provided by the Hall element to the electromagnetic driving module;

wherein the first spring plate is in the form of hollowed out thin metal plate; in addition, each one of the first spring members of first spring plate comprises: a first outer rim connected to the movable frame, a first inner rim connected to the lens holder, at least one first inner string extending and connecting between the first outer rim and the first inner rim, and a first contact located at the first outer rim; each one of the suspension wires has its one end thereof being correspondingly connected to one of the first contacts;

wherein the electromagnetic lens driving device further comprises a second circuit board; the Hall element is furnished on the second circuit board; a sensing magnet for Z-axis position is furnished on the lens holder at a location corresponding to the Hall element; in addition, the end of each suspension wire which is connected to the first contact is coupled with the second circuit board, and thus is further coupled to one of the pins of the Hall element via the second circuit board.

In a preferred embodiment, the electric coupling structure further comprises a second spring plate located at a lower side of the lens holder along the Z-axis direction opposite to the first spring plate; the second spring plate comprises at least two individual and separated second spring member; each one of the second spring members comprises: a second outer rim connected to the movable frame, a second inner rim fixed on the lens holder for flexibly retaining a bottom position of the lens holder along the Z-axis direction, at least one second inner string extending and connecting between the second outer rim and the second inner rim, and a second contact located at the second outer rim; wherein the electromagnetic driving module comprises at least a driving coil furnished on the lens holder and at least two driving magnets mounted on the movable frame and corresponding to the driving coil; wherein the second inner rim of each second spring member is electric coupled with the driving coil of the electromagnetic driving module; in addition, the second contact of each second spring member is coupled to the second circuit board and thus is further coupled with one of the pins of the Hall element.

In a preferred embodiment, the second contact of each one of the second spring members is coupled to the second circuit board by means of one of the following structures: bending a thin elongated extending part extended from the second contact toward the second circuit so as to let an end of the extending part connect to the second circuit board, and soldering a connecting wire at the second contact and let an end of the connecting wire connect to the second circuit board.

In a preferred embodiment, the first spring plate includes at least six independent and separated first spring members; wherein, among these six first spring members, there are four first spring members that each of these four first spring members includes the first contact which is coupled with the control unit by means of the suspension wire; while the other two first spring members do not connect to the suspension wires and are coupled to the electromagnetic driving module via the first inner rim;

wherein the electromagnetic driving module comprises at least a driving coil furnished on the lens holder and at least two driving magnets mounted on the movable frame and corresponding to the driving coil;

wherein the first inner rim of each one of the other two first spring members is coupled with the coil of the electromagnetic driving module; in addition, the first outer rim of each one of the other two first spring members is coupled to the second circuit board and is further coupled to one of the pins of the Hall element in order to supply the current to the electromagnetic driving module in order to control operations of the electromagnetic driving module.

In a preferred embodiment, the OIS module comprises:

at least a first stabilizing coil furnished on the first circuit board and coupled to the control unit;

at least a second stabilizing coil furnished on the first circuit board and are perpendicular to the first stabilizing coils; in addition, the second stabilizing coils being coupled to the control unit;

at least a first stabilizing magnet mounted on the movable frame and corresponding to the first stabilizing coil;

at least a second stabilizing magnet mounted on the movable frame and corresponding to the second stabilizing coil; and

at least two position sensors mounted on the first circuit board and coupled to the control unit; the at least two position sensors being used to detect the position of the movable frame relative to the first circuit board along the X-axis direction and the Y-axis direction;

wherein, the first and second stabilizing magnets are the same with the driving magnets of the electromagnetic driving module.

All these objects are achieved by the suspension mechanism for an optical image anti-shake device described below.

