TWI428009B - Camera module and autofocus method for the same - Google Patents

Description

Camera module and its autofocus method

The invention relates to a camera module, in particular to a camera module and an autofocus method thereof.

With the development of camera technology, camera modules are widely used in camera devices for various purposes. Camera modules are combined with various portable electronic devices such as mobile phones, video cameras, computers, etc., and are favored by many consumers.

The camera module generally includes a drive motor, at least one lens module driven by the drive motor, and a photosensitive element optically coupled to the lens module. The lens module can include one or a plurality of lenses that are optically coupled to the photosensitive element. Preferably, the center point of the photosensitive element is on the optical axis of the one or more lenses. The drive motor drives the lens module to move relative to the photosensitive element to find an optimal resolution imaging position for autofocus.

However, since the driving motor occupies a large space, driving the lens module by using the driving motor may cause the entire camera module to be large in size and complicated in structure, and cannot meet the requirements of lightness, thinness and shortness.

In order to overcome the above disadvantages, a prior art lens module uses a voice coil magnet (VCM) to drive the lens module to move relative to the photosensitive member to achieve autofocus. For details, please refer to Tae-Kyu Kim et al. Published in Acoustics, Speech and Signal Processing, Fast Auto-Focus Control Algorithm Using the VCM Hysteresis Compensation in the Mobile Phone Camera. But pick The use of VCM to drive the lens module relative to the photosensitive element to achieve the function of autofocus, requires the design of a complex snap structure, not only high manufacturing costs, but also low yield.

In view of this, it is necessary to provide a camera module having a simple structure and a low manufacturing cost and an autofocus method thereof.

A camera module includes a lens holder, a lens barrel, an image sensor, an electro-deformation element, and a control circuit. The image sensor is disposed on the lens holder. The lens barrel is mated with the lens holder, and an optical element is disposed therein. The optical component is optically coupled to the image sensor. The electro-deformable element is coupled to the image sensor. The control circuit is electrically connected to the image sensor and the electro-deformation element for supplying a driving voltage to the electro-deformable element, so that the electro-deformable element is deformed along the optical axis direction of the camera module, thereby driving The image sensor moves in the optical axis direction.

An autofocus method for a camera module as described above, comprising the steps of: the control circuit provides a plurality of driving voltages to the electro-deformable component to cause a plurality of corresponding deformations thereof, thereby driving the image sensor to move along the optical axis direction to a plurality of a position and an image signal obtained by the image sensor at a plurality of positions; the control circuit receives the complex image signal, respectively calculating a sharpness value of each image signal, and recording the image sharpness value at a maximum The voltage value is provided by the control circuit to the driving voltage corresponding to the maximum image sharpness value of the electro-deformable component, so that the electro-deformed component is deformed and the image sensor is moved to a position corresponding to the maximum image sharpness value to complete auto focus.

The camera module of the technical solution has the following advantages: firstly, the autofocus is implemented by moving the image sensor, which simplifies the structure of the camera module compared with the traditional method of moving the lens module; secondly, The electroactive polymer (EAP), which is deformed to a certain extent under different driving voltages, produces an electro-deformable component, which further reduces the size of the camera module compared to the prior art stepping motor, voice coil motor and the like. Suitable for the current trend of miniaturization of camera modules.

The technical solution will be further described in detail below with reference to the accompanying drawings and embodiments.

Please refer to FIG. 1 , which is a camera module 100 according to a first embodiment of the present disclosure. The camera module 100 includes a lens holder 110 , a lens barrel 120 , an image sensor 130 , a displacement guiding element 140 , an electro-deformation element 150 , and a control circuit . 160 and a circuit board 170 for packaging the control circuit 160.

The lens holder 110 has a top receiving cavity 112 and a bottom receiving cavity 113 that communicate with each other. The lens barrel 120 is housed in a top accommodating cavity 112. The lens barrel 120 is provided with optical elements such as a plurality of optical lenses 121 arranged in order. In this embodiment, the lens barrel 120 and the lens holder 110 are fixed by dispensing. The image sensor 130, the displacement guiding element 140, the electro-deformable element 150 and the control circuit 160 are all accommodated in the bottom receiving cavity 113. The circuit board 170 is fixed on one side of the lens holder 110 away from the top accommodating cavity 112, that is, away from one side of the lens barrel 120, and the control circuit 160 is packaged on the circuit board 170.

The image sensor 130 and various optical lenses 121 in the lens barrel 120 The coupling is coupled and electrically coupled to the control circuit 160 by the circuit board 170. The image sensor 130 includes an image sensor 131 and an image signal processing chip (ISP Chip) 132. The photosensitive element 131 can be a charge coupled device or a complementary metal oxide semiconductor. Preferably, the photosensitive element 131 is integrated with the image signal processing circuit 132. The image sensor 130 uses a ceramic leaded chip carrier (CLCC), a plastic leaded chip carrier (PLCC) or a chip scale package (CSP). Referring to FIG. 2 , in the embodiment, the image sensor 130 is square, and has two pins 133 and three protrusions 134 for electrically connecting to the circuit board 170 . Preferably, a cover glass of the image sensor 130 near one side of the lens barrel 120 may be disposed to prevent contamination of the image sensor 130 by dust or the like.

Referring to FIG. 1 and FIG. 2 , the displacement guiding component 140 is fixed on the circuit board 170 and surrounds the image sensor 130 , and its shape matches the shape of the image sensor 130 for guiding the image sensor. The direction of displacement of 130. In this embodiment, the displacement guiding element 140 is a square frame surrounded by four rectangular plates. The central axis of the square frame is parallel to the optical axis 60 of the camera module 100 to ensure the image sensor 130. The direction of movement is parallel to the optical axis 60. The displacement guiding member 140 has at least one opening 141 for facilitating the pin 133 of the image sensor 130 to be electrically connected to the circuit board 170 through the opening 141 to be electrically connected to the control circuit 160. The slide guiding member 140 further defines a sliding rail 142 corresponding to the protruding portion 134 of the image sensor 130. The sliding rail 142 can be disposed in a groove parallel to the optical axis 60 in the inner wall of the panel for receiving The protrusion 134 is such that the moving direction of the image sensor 130 is accurate and stable. In this embodiment, the displacement guiding member 140 has an opening 141 and three sliding rails 142. One of the four plates constituting the square frame has an opening 141, and each of the remaining plates has a sliding rail 142.

The electro-deformable component 150 is connected to the image sensor 130 and disposed between the image sensor 130 and the circuit board 170 in a direction perpendicular to the optical axis 60. The electro-deformable component 150 is made of an electroactive polymer (EAP). A sheet, block or other structure for generating a deformation parallel to the direction of the optical axis 60 in accordance with the driving voltage. The electroactive polymer (EAP) may be a Dielectric Elastomer, a Graft Elastomer or a ferroelectric polymer. In this embodiment, the electro-deformable element 150 is made of a polyurethane elastomer in a Dielectric Elastomer. After being applied with a voltage, it is contracted in the direction of the applied voltage under the attraction of the electrostatic force. Elongate perpendicular to the direction in which the voltage is applied.

It can be understood that the electro-deformation element 150 can also be connected to the image sensor 130 near one side of the lens barrel 120. For example, the electro-deformable element 150 can also be disposed between the cover glass and the image sensor 130. At this time, in order to avoid affecting the imaging of the camera module 100, the electro-deformable element 150 should be made of a light-transmissive electroactive material.

Control circuit 160 includes a voltage control module 161 and an image processing module 162, as shown in FIG. The image processing module 162 is electrically connected to the image sensor 130 for acquiring and processing the image signal of the image sensor 130. The voltage control module 161 is coupled to the electro-deformable component 150 for providing a voltage to the electro-deformable component 150 and controlling the driving voltage. small. When the control circuit 160 supplies the electro-deformable element 150 with a driving voltage perpendicular to the optical axis 60, the electro-deformable element 150 contracts in a direction perpendicular to the optical axis 60 while extending in the direction of the optical axis 60, thereby driving the connection thereto. The image sensor 130 moves toward the lens barrel 120 in the direction of the parallel optical axis 60. Specifically, please refer to FIG. 1 to FIG. 4, when the control circuit 160 provides a driving voltage to the electro-deformable component 150, and the length of the electro-deformable component 150 increases along the optical axis 60 to drive the image sensor. The 130 moves in a direction parallel to the optical axis 60, and the image sensor 130 moves from the initial position relative to the lens barrel 120 to the first position, increasing the magnitude of the driving voltage, and the length of the electro-deformable element 150 in the direction of the optical axis 60 again. Incidentally, the image sensor 130 moves from the first position relative to the lens barrel 120 to the second position to achieve autofocus. When the control circuit 160 stops providing the driving voltage, the electro-deformable element 150 returns to the initial state and drives the image sensor 130 back to the initial position.

Referring to FIG. 1 to FIG. 4 , the autofocus method of the camera module 100 may include the following steps: the voltage control module 161 of the control circuit 160 provides a plurality of driving voltages to the electro-deformable component 150 to cause a plurality of corresponding deformations. Thereby, the image sensor 130 is moved to the plurality of positions along the optical axis 60, and the image sensor 130 acquires the image signal at the plurality of positions; the image processing module 162 of the control circuit 160 receives the plurality Image signal, respectively calculating the sharpness value of each image signal, and recording the voltage value corresponding to the maximum image sharpness value; the voltage control module 161 of the control circuit 160 provides the electromorphic element The driving voltage of the image 150 with the highest image sharpness value causes the electro-deformable element 150 to deform and drives the image sensor 130 to move to the position where the image sharpness value is maximum to complete the autofocus.

The sharpness value is a resolution value, a contrast value, or a Modulation Transfer Function (MTF), and the modulus transfer function value is a comprehensive evaluation value for imaging quality, which is better than pure resolution or contrast. Reflects image quality.

Referring to FIG. 5 , the camera module provided in the second embodiment of the present invention is substantially similar to the camera module 100 provided in the first embodiment. The difference is that the image sensor 230 of the embodiment is circular and has a A protrusion 234. The displacement guiding member 240 is correspondingly a circular cylinder and has an opening 241 and a slide rail 242 for receiving the projection 234. It can be understood that the displacement guiding element 240 can also be a polygonal cylinder of a pentagonal shape, a hexagonal shape or the like, or other irregularly shaped cylinders, and only the displacement guiding element 240 needs to correspond to the image sensor 230.

Referring to FIG. 6 , the camera module 300 provided by the third embodiment of the present invention is substantially similar to the camera module 100 provided by the first embodiment. The difference is that the lens barrel 320 is partially received in the top receiving cavity 312 . The rest protrudes beyond the mirror mount 310. Moreover, one end of the lens holder 310 and the lens barrel has an internal thread 311. The lens barrel 320 is received at one end of the lens holder 310 and has an external thread 321 . The internal thread 311 and the external thread 321 are between the lens holder 310 and the lens barrel 320. The screw is fixed and fixed. Since the present embodiment achieves autofocus by moving the image sensor 330, the structure of the lens holder 310 and the fixing manner between the lens holder 310 and the lens barrel 320 are simplified.

The camera module of the technical solution has the following advantages: firstly, the autofocus is implemented by moving the image sensor, which simplifies the structure of the camera module compared with the traditional method of moving the lens module; secondly, The electroactive polymer (EAP), which is deformed to a certain extent under different driving voltages, produces an electro-deformable component, which further reduces the size of the camera module compared to the prior art stepping motor, voice coil motor and the like. Suitable for the current trend of miniaturization of camera modules.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Camera module ‧‧100,300

Mirror holder ‧‧1101,310

Top housing cavity ‧‧‧112, 312

Lens barrel ‧ ‧ 120, 320

Image sensor ‧‧130,230,330

Prominence ‧‧‧134,234

Displacement guiding element ‧‧‧140, 240

Opening ‧‧‧141,241

Image signal processing circuit ‧‧‧132

Slide rails ‧‧142,242

Photosensitive element ‧‧‧131

Pin ‧‧‧133

Bottom accommodating chamber ‧‧113

Optical lenses ‧‧‧121

Image Processing Module ‧‧‧162

Control circuit ‧‧‧160

Electro-deformation element ‧‧‧150

Optical axis ‧‧60

Voltage Control Module ‧‧‧161

Circuit board ‧ ‧ 170

Internal thread ‧‧ 311

External thread ‧ ‧ 321

FIG. 1 is a schematic cross-sectional view of a camera module according to a first embodiment of the present technical solution.

FIG. 2 is a schematic structural diagram of a displacement guiding component and a circuit board of a camera module according to a first embodiment of the present technical solution.

FIG. 3 is a schematic diagram of signal processing for autofocusing of the camera module provided by the first embodiment of the present technical solution.

4 is a cross-sectional view showing a focus state of a camera module according to a first embodiment of the present technical solution.

FIG. 5 is a schematic structural diagram of a displacement guiding component of a camera module according to a second embodiment of the present technical solution.

FIG. 6 is a schematic cross-sectional view of a camera module according to a third embodiment of the present technical solution.

Camera module ‧‧100

Mirror seat ‧‧110

Top accommodating chamber ‧‧112

Bottom accommodating chamber ‧‧113

Mirror ‧‧120

Optical lenses ‧‧‧121

Image sensor ‧‧130

Image signal processing circuit ‧‧‧132

Photosensitive element ‧‧‧131

Optical axis ‧‧60

Displacement guide element ‧‧‧140

Electro-deformation element ‧‧‧150

Control circuit ‧‧‧160

Circuit board ‧ ‧ 170

Claims (9)

A camera module includes a lens holder, a lens barrel and an image sensor. The image sensor is disposed on the lens holder. The lens barrel cooperates with the lens holder, and is provided with an optical component, the optical component and the image sense The optical coupling of the detector is improved in that the camera module further includes: an electro-deformable component connected to the image sensor; and a control circuit electrically connected to the image sensor and the electro-deformable component, A driving voltage is applied to the electro-deformable component to deform the electro-deformable component along the optical axis of the camera module to drive the image sensor to move along the optical axis. The camera module of claim 1, wherein the lens holder has a top receiving cavity and a bottom receiving cavity, wherein the lens barrel is disposed in the top receiving cavity, the image sensor, and the image sensor The deformation component and the control circuit are all accommodated in the bottom receiving cavity. The camera module of claim 1, wherein the camera module further includes a circuit board for packaging the control circuit, the circuit board is fixed on a side of the lens holder away from the lens barrel, The electro-deformable component is disposed between the image sensor and the circuit board. The camera module of claim 1, wherein the camera module further comprises a cover glass disposed between the image sensor and the cover glass. The camera module of claim 1, wherein the camera module further includes a displacement guiding member for guiding a moving direction of the image sensor, the displacement guiding member being disposed around the image sensor, And its shape and The shape of the image sensor matches. The camera module of claim 5, wherein the image sensor has at least one protrusion, the displacement guiding element has at least one slide rail corresponding to the protrusion for receiving The protrusion. The camera module of claim 1, wherein the electro-deformable element is a sheet or block made of an electroactive material. The camera module of claim 1, wherein the control circuit comprises a voltage control module and an image processing module, the voltage control module being coupled to the electro-deformable component for controlling supply to the electro-deformable component The image processing module is electrically connected to the image sensor for acquiring and processing an image signal of the image sensor. An autofocus method for a camera module according to claim 1, comprising the steps of: the control circuit providing a plurality of driving voltages to the electro-deformable component to cause a plurality of corresponding deformations thereof, thereby driving the image sensor Moving to a plurality of positions along the optical axis direction, and causing the image sensor to acquire an image signal at a plurality of positions; the control circuit receives the complex image signal, respectively calculating a sharpness value of each image signal, and Recording a voltage value when the image sharpness value is maximum; the control circuit supplies the driving voltage to the electro-deformable component when the image signal sharpness value is the largest, so that the electro-deformable component is deformed and the image sensor is moved to the image clear The position at the maximum value is used to complete the autofocus.