Patent Publication Number: US-9432560-B2

Title: Image capturing module for saving focusing time and increasing assembly flatness and method of assembling the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant disclosure relates to an image capturing module and a method of assembling the same, and more particularly to an image capturing module for saving focusing time and increasing assembly flatness and a method of assembling the same. 
     2. Description of Related Art 
     Recently, it has become more and more popular for portable devices such as mobile phones or PDA to be equipped with an imaging module. Furthermore, since the market requires these portable devices to have more powerful functions and smaller sizes, it is necessary for the imaging module to generate high quality pictures and to be of small size. One improvement of picture quality is to increase the number of pixels. The pixel number of an imaging module has already increased from the VGA-level 30 pixels to 2, 3 or even 8 million pixels, which is now common in the market. Another improvement lies in the definition of the image. Thus, the imaging module of a portable device also develops from a fixed-focus mode to auto-focus mode or even optical zoom mode. 
     The auto-focus mode employs the principle of moving the lens in the imaging module suitably according to various distances of targets, whereby the optical image of the desired target is focused correctly on an image sensor to generate a clear image. The common ways of activating the lens to move in the imaging module include activating by a stepping motor, piezoelectric motor and voice coil motor (VCM). However, when both the image sensor and the sensor housing are disposed on the same stacked datum plane of the circuit board, the assembly tilt angle of the sensor housing relative to the image sensor would be increased, thus the image quality provided by the imaging module cannot be improved due to the increased assembly tilt angle. Besides, it is very time consuming to manually focus the imaging module relative to the image sensor. 
     SUMMARY OF THE INVENTION 
     One aspect of the instant disclosure relates to an image capturing module for saving focusing time and increasing assembly flatness and a method of assembling the same. 
     One of the embodiments of the instant disclosure provides an image capturing module for saving focusing time and increasing assembly flatness, comprising: an image sensing unit, a housing frame, an actuator structure and an optical filter. The image sensing unit includes a carrier substrate and an image sensing chip disposed on the carrier substrate and electrically connected to the carrier substrate, wherein the image sensing chip has a first horizontal top surface on the top side thereof, and the first horizontal top surface is obtained by a horizontal correction system using a laser light source. The housing frame is disposed on the carrier substrate to surround the image sensing chip. The actuator structure is disposed on the housing frame and above the image sensing chip, wherein the actuator structure includes a lens holder disposed on the housing frame and a movable lens assembly disposed inside the lens holder and above the image sensing chip, the lens holder includes a surrounding movable member movably disposed therein, the movable lens assembly is fixed inside the surrounding movable member through at least two separate bonding glue, and the movable lens assembly is movably disposed inside the lens holder through the surrounding movable member. The optical filter is disposed on the housing frame and between the image sensing chip and the movable lens assembly, wherein the optical filter has a second horizontal top surface on the top side thereof, and the second horizontal top surface is obtained by the horizontal correction system using the laser light source, and the distance from the second horizontal top surface of the optical filter to the first horizontal top surface of the image sensing chip is defined as a predetermined fixed focusing distance. Whereby, the movable lens assembly is directly disposed on the second horizontal top surface of the optical filter to save the focusing time of the movable lens assembly relative to the image sensing chip, and the first horizontal top surface of the image sensing chip and the second horizontal top surface of the optical filter are horizontal to each other for increasing the assembly flatness of the movable lens assembly relative to the image sensing chip. 
     Another one of the embodiments of the instant disclosure provides an image capturing module for saving focusing time and increasing assembly flatness, comprising: an image sensing unit, a housing frame, an actuator structure and an optical filter. The image sensing unit includes a carrier substrate and an image sensing chip disposed on the carrier substrate and electrically connected to the carrier substrate, wherein the image sensing chip has a first horizontal top surface on the top side thereof. The housing frame is disposed on the carrier substrate to surround the image sensing chip. The actuator structure is disposed on the housing frame and above the image sensing chip, wherein the actuator structure includes a lens holder disposed on the housing frame and a movable lens assembly movably disposed inside the lens holder and above the image sensing chip. The optical filter is disposed on the housing frame and between the image sensing chip and the movable lens assembly, wherein the optical filter has a second horizontal top surface on the top side thereof, and the distance from the second horizontal top surface of the optical filter to the first horizontal top surface of the image sensing chip is defined as a predetermined fixed focusing distance. Whereby, the movable lens assembly is directly disposed on the second horizontal top surface of the optical filter to save the focusing time of the movable lens assembly relative to the image sensing chip, and the first horizontal top surface of the image sensing chip and the second horizontal top surface of the optical filter are horizontal to each other for increasing the assembly flatness of the movable lens assembly relative to the image sensing chip. 
     Yet another one of the embodiments of the instant disclosure provides a method of assembling an image capturing module for saving focusing time and increasing assembly flatness, comprising: providing an image sensing unit and a housing frame, wherein the image sensing unit includes a carrier substrate and an image sensing chip disposed on the carrier substrate and electrically connected to the carrier substrate, and the housing frame is disposed on the carrier substrate to surround the image sensing chip; obtaining a first horizontal top surface on the top side of the image sensing chip by a horizontal correction system using a laser light source; placing an optical filter on the housing frame and above the image sensing chip; obtaining a second horizontal top surface on the top side of the optical filter by the horizontal correction system using the laser light source, wherein the distance from the second horizontal top surface of the optical filter to the first horizontal top surface of the image sensing chip is defined as a predetermined fixed focusing distance; providing an actuator structure disposed on the housing frame and above the image sensing chip, wherein the actuator structure includes a lens holder disposed on the housing frame and a movable lens assembly disposed inside the lens holder and above the image sensing chip, and the lens holder includes a surrounding movable member movably disposed therein, wherein the movable lens assembly is directly disposed on the second horizontal top surface of the optical filter to save the focusing time of the movable lens assembly relative to the image sensing chip, and the first horizontal top surface of the image sensing chip and the second horizontal top surface of the optical filter are horizontal to each other for increasing the assembly flatness of the movable lens assembly relative to the image sensing chip; and then fixing the movable lens assembly inside the surrounding movable member through at least two separate bonding glue, wherein the movable lens assembly is movably disposed inside the lens holder through the surrounding movable member. 
     Therefore, the first horizontal top surface on the top side of the image sensing chip and the second horizontal top surface on the top side of the optical filter can be obtained by the horizontal correction system using the same laser light source, thus when the second horizontal top surface of the optical filter is horizontal to the first horizontal top surface of the image sensing chip, the assembly tilt angle of the movable lens assembly relative to the image sensing chip can be reduced for ensuring the flatness of the movable lens assembly relative to the image sensing chip. More precisely, when the distance from the second horizontal top surface of the optical filter to the first horizontal top surface of the image sensing chip is defined as a predetermined fixed focusing distance in advance, the movable lens assembly can be directly disposed on the second horizontal top surface of the optical filter to cut down the focusing time of the movable lens assembly relative to the image sensing chip. 
     To further understand the techniques, means and effects of the instant disclosure applied for achieving the prescribed objectives, the following detailed descriptions and appended drawings are hereby referred to, such that, and through which, the purposes, features and aspects of the instant disclosure can be thoroughly and concretely appreciated. However, the appended drawings are provided solely for reference and illustration, without any intention to limit the instant disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a flowchart of the method of assembling an image capturing module for saving focusing time and increasing assembly flatness according to the instant disclosure; 
         FIG. 2  shows a lateral, cross-sectional, schematic view of the assembly steps S 100  and S 102  of the method of assembling an image capturing module for saving focusing time and increasing assembly flatness according to the instant disclosure; 
         FIG. 3  shows a lateral, cross-sectional, schematic view of the assembly steps S 104  and S 106  of the method of assembling an image capturing module for saving focusing time and increasing assembly flatness according to the instant disclosure; and 
         FIG. 4  shows a lateral, cross-sectional, schematic view of the assembly steps S 108  and S 110  of the method of assembling an image capturing module for saving focusing time and increasing assembly flatness according to the instant disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The embodiments of “an image capturing module for saving focusing time and increasing assembly flatness and a method of assembling the same” of the instant disclosure are described. Other advantages and objectives of the instant disclosure can be easily understood by one skilled in the art from the disclosure. The instant disclosure can be applied in different embodiments. Various modifications and variations can be made to various details in the description for different applications without departing from the scope of the instant disclosure. The drawings of the instant disclosure are provided only for simple illustrations, but are not drawn to scale and do not reflect the actual relative dimensions. The following embodiments are provided to describe in detail the concept of the instant disclosure, and are not intended to limit the scope thereof in any way. 
     Referring to  FIG. 1  to  FIG. 4 , the instant disclosure provides a method of assembling an image capturing module M for saving focusing time and increasing assembly flatness, comprising the following steps: 
     First, the step S 100  is that: referring to  FIG. 1  and  FIG. 2 , providing an image sensing unit  1  and a housing frame  2 , wherein the image sensing unit  1  includes a carrier substrate  10  (or a carrying substrate) and an image sensing chip  11  disposed on the carrier substrate  10  and electrically connected to the carrier substrate  10 , and the housing frame  2  is disposed on the carrier substrate  10  to surround the image sensing chip  11 . For example, the image sensing chip  11  may be a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and the image sensing chip  11  can be adhesively disposed on the carrier substrate  10  through any type of adhesive material (not labeled) such as UV adhesive glue, thermosetting glue or curing glue applied to oven etc. Moreover, the housing frame  2  can be adhesively disposed on the carrier substrate  10  through any type of adhesive material (not labeled) such as UV adhesive glue, thermosetting glue or curing glue applied to oven etc. In addition, the carrier substrate  10  may be a circuit substrate having a plurality of conductive pads (not labeled) disposed on the top surface of the circuit substrate, and the image sensing chip  11  has a plurality of conductive pads (not labeled) disposed on the top surface of the image sensing chip  11 . Each conductive pad (not labeled) of the image sensing chip  11  can be electrically connected to the corresponding conductive pad (not labeled) of the carrier substrate  10  through a corresponding conductive wire (not labeled), thus the image sensing chip  11  can be electrically connected with the carrier substrate  10  through the conductive wires (not labeled). 
     Next, the step S 102  is that: referring to  FIG. 1  and  FIG. 2 , obtaining a first horizontal top surface  110  on the top side of the image sensing chip  11  by a horizontal correction system using a laser light source S. More precisely, the laser light source S is disposed at a predetermined position P (such as a fixing position) above the image sensing chip  11  to generate a first laser light beam L 1  that is directly and vertically projected onto the first horizontal top surface  110  of the image sensing chip  11 , and the first laser light beam L 1  generated by the laser light source S is reflected by the first horizontal top surface  110  of the image sensing chip  11  to form a first reflecting light beam R 1  that is directly and vertically projected onto the predetermined position P or very close to the predetermined position P. In other words, when the top side of the image sensing chip  11  is adjusted to become a first horizontal top surface  110 , the first laser light beam L 1  can be reflected by the first horizontal top surface  110  to form the first reflecting light beam R 1  that vertically returns to the predetermined position P, or the first reflecting light beam R 1  is very close to the predetermined position P due to the permissible error. At present, the top side of the image sensing chip  11  is exactly the first horizontal top surface  110  as a horizontal datum plane. 
     Then, the step S 104  is that: referring to  FIG. 1  and  FIG. 3 , placing an optical filter  4  on the housing frame  2  and above the image sensing chip  11 . More precisely, as shown in  FIG. 3 , the housing frame  2  has a top opening  200  disposed on the top side thereof and right above the image sensing chip  11 , and the top opening  200  of the housing frame  2  is enclosed by the optical filter  4 . For example, the optical filter  4  may be a flat glass plate having an infrared (IR) coated layer and/or an antireflection (AR) coating layer, and the optical filter  4  can be fixed inside a concave space (not labeled) of the housing frame  2  through first bonding glue (not labeled) for enclosing the top opening  200  of the housing frame  2 . 
     Afterward, the step S 106  is that: referring to  FIG. 1  and  FIG. 3 , obtaining a second horizontal top surface  400  on the top side of the optical filter  4  by the horizontal correction system using the laser light source S, wherein the distance from the second horizontal top surface  400  of the optical filter  4  to the first horizontal top surface  110  of the image sensing chip  11  is defined as a predetermined fixed focusing distance D. More precisely, the laser light source S (such as a laser level) is disposed at a predetermined position P above the optical filter  4  to generate a second laser light beam L 2  that is directly and vertically projected onto the second horizontal top surface  400  of the optical filter  4 , and the second laser light beam L 2  generated by the laser light source S is reflected by the second horizontal top surface  400  of the optical filter  4  to form a second reflecting light beam R 2  that is directly and vertically projected onto the predetermined position P or very close to the predetermined position P. In other words, when the top side of the optical filter  4  is adjusted to become a second horizontal top surface  400 , the second laser light beam L 2  can be reflected by the second horizontal top surface  400  to form the second reflecting light beam R 2  that vertically returns to the predetermined position P, or the second reflecting light beam R 2  is very close to the predetermined position P due to the permissible error. At present, the top side of the optical filter  4  can be formed as the second horizontal top surface  400  that is horizontal to the first horizontal top surface  110 . 
     It is worth mentioning that the first laser light beam L 1  generated by the laser light source S also can be inclinedly projected onto the first horizontal top surface  110  of the image sensing chip  11 , and the second laser light beam L 2  generated by the laser light source S also can be slantwise projected onto the second horizontal top surface  400  of the optical filter  4 . When the first reflecting light beam R 1  and the second reflecting light beam R 2  are projected onto the same position, the top side (such as the second horizontal top surface  400 ) of the optical filter  4  also can be horizontal to the top side (such as the first horizontal top surface  110 ) of the image sensing chip  11 , thus the assembly tilt angle of the movable lens assembly  31  relative to the image sensing chip  11  also can be reduced for ensuring the flatness of the movable lens assembly  31  relative to the image sensing chip  11 . 
     Afterward, the step S 108  is that: referring to  FIG. 1  and  FIG. 3 , providing an actuator structure  3  disposed on the housing frame  2  and above the image sensing chip  11 , wherein the actuator structure  3  includes a lens holder  30  disposed on the housing frame  2  and a movable lens assembly  31  disposed inside the lens holder  30  and above the image sensing chip  11 , and the lens holder  30  includes a surrounding (annular) movable member  30 M movably disposed therein. In addition, the movable lens assembly  31  is directly disposed on the second horizontal top surface  400  of the optical filter  4  to save the focusing time of the movable lens assembly  31  relative to the image sensing chip  11 , and the first horizontal top surface  110  of the image sensing chip  11  and the second horizontal top surface  400  of the optical filter  4  are horizontal to each other for increasing the assembly flatness of the movable lens assembly  31  relative to the image sensing chip  11 . Whereby, the first horizontal top surface  110  of the image sensing chip  11  and the second horizontal top surface  400  of the optical filter  4  are horizontal to each other, thus when the movable lens assembly  31  is directly disposed on the second horizontal top surface  400  of the optical filter  4 , not only the assembly tilt angle of the movable lens assembly  31  relative to the image sensing chip  11  can be reduced for ensuring the flatness of the movable lens assembly  31  relative to the image sensing chip  11 , but also the focusing time of the movable lens assembly  31  relative to the image sensing chip  11  can be cut down. 
     More precisely, the movable lens assembly  31  has a bottom plane  310  on the bottom side thereof for directly contacting the second horizontal top surface  400  of the optical filter  4 , and the predetermined fixed focusing distance D from the second horizontal top surface  400  of the optical filter  4  to the first horizontal top surface  110  of the image sensing chip  11  is totally or substantially the same as an adjustable focusing distance F from the bottom plane  310  of the movable lens assembly  31  to the first horizontal top surface  110  of the image sensing chip  11 . 
     For example, the surrounding movable member  30 M has an inner surrounding surface  300  such as a threadless surface, and the movable lens assembly  31  has an outer perimeter surface  311  such as a threadless surface. In addition, the lens holder  30  also can be adhesively disposed on the housing frame  2  through any type of adhesive material (not labeled) such as UV adhesive glue, thermosetting glue or curing glue applied to oven etc., and the movable lens assembly  31  may be an optical lens group that is composed of a plurality of optical lenses (not labeled). It is worth mentioning that, as shown in  FIG. 4 , the actuator structure  3  may be a voice coil motor actuator, but the voice coil motor actuator used in the first embodiment is merely an example and is not meant to limit the instant disclosure. For example, the actuator structure  3  can be replaced by an optical auxiliary structure having a fixed lens assembly. 
     Finally, the step S 110  is that: referring to  FIG. 1 ,  FIG. 4  and  FIG. 5 , when the second horizontal top surface  400  of the optical filter  4  is horizontal to the first horizontal top surface  110  of the image sensing chip  11  and the movable lens assembly  31  is directly disposed on the second horizontal top surface  400  of the optical filter  4 , fixing the movable lens assembly  31  inside the surrounding movable member  30 M through at least two separate bonding glue H, wherein the movable lens assembly  31  is movably disposed inside the lens holder  30  through the surrounding movable member  30 M. 
     Whereby, the instant disclosure provides an image capturing module M for saving focusing time and increasing assembly flatness via the assembly steps from S 100  to S 110 , and the image capturing module M includes an image sensing unit  1 , a housing frame  2 , an actuator structure  3  and an optical filter  4 . The image sensing chip  11  has a first horizontal top surface  110  on the top side thereof, the optical filter  4  has a second horizontal top surface  400  on the top side thereof, and the first horizontal top surface  110  and the second horizontal top surface  400  are obtained by a horizontal correction system using a laser light source S. Therefore, the first horizontal top surface  110  of the image sensing chip  11  and the second horizontal top surface  400  of the optical filter  4  are horizontal to each other, for increasing the assembly flatness of the movable lens assembly  31  relative to the image sensing chip  11 . Hence, when the distance from the second horizontal top surface  400  of the optical filter  4  to the first horizontal top surface  110  of the image sensing chip  11  is defined as a predetermined fixed focusing distance D in advance, not only the movable lens assembly  31  can be directly disposed on the second horizontal top surface  400  of the optical filter  4  to cut down the focusing time of the movable lens assembly  31  relative to the image sensing chip  11 , but also the first horizontal top surface  110  of the image sensing chip  11  and the second horizontal top surface  400  of the optical filter  4  can be horizontal to each other for increasing the assembly flatness of the movable lens assembly  31  relative to the image sensing chip  11 . 
     In conclusion, the first horizontal top surface  110  on the top side of the image sensing chip  11  and the second horizontal top surface  400  on the top side of the optical filter  4  can be obtained by the horizontal correction system using the same laser light source S, thus when the second horizontal top surface  400  of the optical filter  4  is horizontal to the first horizontal top surface  110  of the image sensing chip  11 , the assembly tilt angle of the movable lens assembly  31  relative to the image sensing chip  11  can be reduced for ensuring the flatness of the movable lens assembly  31  relative to the image sensing chip  11 . More precisely, when the distance from the second horizontal top surface  400  of the optical filter  4  to the first horizontal top surface  110  of the image sensing chip  11  is defined as a predetermined fixed focusing distance D in advance, the movable lens assembly  31  can be directly disposed on the second horizontal top surface  400  of the optical filter  4  to cut down the focusing time of the movable lens assembly  31  relative to the image sensing chip  11 . 
     The aforementioned descriptions merely represent the preferred embodiments of the instant disclosure, without any intention to limit the scope of the instant disclosure which is fully described only within the following claims. Various equivalent changes, alterations or modifications based on the claims of the instant disclosure are all, consequently, viewed as being embraced by the scope of the instant disclosure.