Abstract:
A spacer ( 20 ), configured to be disposed between two lenses ( 12, 13 ) of a lens module ( 10 ) in order to separate the two lenses by a predetermined distance, includes a through hole ( 22 ) penetrating therethrough for permitting light to pass therethrough, and an upper surface ( 201 ) configured for receiving adhesive thereon. The upper surface has a slot ( 23 ) defined therein around the through hole. The slot is configured for receiving excess adhesive. A lens module using the spacer and a method of assembling the lens module are also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to a co-pending U.S. patent application (Attorney Docket No. US10675), entitled “GLUE DISPENSER FOR LENS MODULE ASSEMBLING”, by Mong-Tung Lin. Such application has the same assignee as the present application and has been concurrently filed herewith. The above-identified application is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention generally relates to optical members for lens modules and lens modules using the optical member, and to a method of assembling the lens module and, more particularly, to a spacer for a lens module, a lens module using the spacer, and a method of assembling the lens module. 
       BACKGROUND 
       [0003]    Portable communication devices, such as mobile phones, personal digital assistants (PDAs) and/or palm-top computers containing digital cameras have become some of the most popular commodities in modern electronics. A typical lens module includes a barrel having a stopper ring therein, a first lens, a spacer and a second lens. In assembly, the first lens and the spacer are sequentially placed in the barrel, and the first lens is sandwiched between the stopper ring and the spacer. Then, an adhesive/glue is applied to the spacer adjacent to an inner circumference of the barrel by employing a syringe with a needle dispensing section. After the gluing process, the second lens is mounted in the barrel and attached to the spacer and the inner circumference of the barrel via the adhesive, so as to fix the first lens and the spacer in the barrel. 
         [0004]    However, in the gluing process, the syringe has to rotate relative to the lens module to apply an adhesive circle or a plurality of adhesive dots onto the spacer. Therefore, the gluing process is time consuming. In addition, it is difficult to precisely control the adhesive amount and distribution, which can seriously affect the quality of the lens module. 
         [0005]    Therefore, an improved spacer, a lens module using the spacer and a method of assembling the lens module are desired in order to overcome the above-described shortcomings. 
       SUMMARY 
       [0006]    In one aspect, a spacer is provided. The spacer is configured to be disposed between two lenses of a lens module in order to separate the two lenses by a predetermined distance, and includes a through hole and an upper surface. The through hole penetrates the spacer for permitting light to pass therethrough. The upper surface is configured for receiving adhesive thereon, and has a slot defined therein around the through hole. The slot is configured for receiving excess adhesive. 
         [0007]    In another aspect, a lens module using the spacer is provided. The lens module includes a barrel, at least two lenses, at least one spacer and an adhesive. The barrel includes a cylindrical wall and a stopper ring. The stopper ring extends inwardly of the cylindrical wall. The lenses are received in the barrel and supported by the stopper ring. The at least one spacer is respectively sandwiched between two adjacent lenses. Each spacer has a through hole penetrating therethrough and an upper surface. The through hole is configured for permitting light to pass therethrough. The upper surface has a slot defined therein around the through hole. The adhesive is applied to an outer circumference of the upper surface of each spacer to adhere the lens to the spacer and the barrel. 
         [0008]    In another aspect of the embodiment, a method of assembling the lens module is provided. The method includes the steps of: providing a barrel; placing a first lens into the barrel; insert a spacer into the barrel and onto the first lens, the spacer having a through hole defined therethrough and an upper surface thereof, the upper surface being distanced apart from the first lens and defining a slot around the through hole; synchronously dispensing a plurality of adhesive dots on an outer circumference of the upper surface of the spacer; and mounting a second lens onto the upper surface of the spacer thereby attaching the second lens to the spacer and the barrel via the adhesive dots. 
         [0009]    Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the present spacer, lens module using the spacer and method of assembling the lens module can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the spacer, lens module using the spacer and method of assembling the lens module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is a schematic, cross-sectional view of a lens module having a spacer according to a preferred embodiment; 
           [0012]      FIG. 2  is an exploded, perspective view of  FIG. 1 ; 
           [0013]      FIG. 3  is a schematic, perspective view of a glue dispenser used in assembling the lens module, according to another preferred embodiment; and 
           [0014]      FIG. 4  is a schematic, cross-sectional view of the lens module in a state when the glue dispenser of  FIG. 3  dispenses glue on the spacer. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    As illustrated in  FIGS. 1 and 2 , a lens module  10 , according to a preferred embodiment, includes a barrel  11 , a first lens  12 , a second lens  13 , a spacer  20 , and a plurality of adhesive/glue dots  31 . 
         [0016]    The barrel  11  is cylindrical, and includes an inner circumferential wall  111  and a cylindrical receiving cavity  113 . The receiving cavity  113  is surrounded by the inner circumferential wall  111 , and is defined to receive optical elements such as the first and second lenses  12 ,  13  and the spacer  20  therein. The barrel  11  further provides a stopper ring  115 , which extends annularly and inwardly from the inner circumferential wall  111  (i.e., wall  111  defining a cylinder) of the barrel  11 , to position and support the optical elements in the receiving cavity  113 . The stopper ring  115  has a supporting surface (not labeled) which is flat and perpendicular to an axis of the barrel  11 . The supporting surface of the stopper ring  113  is used to contact with and support the first lens  12 . 
         [0017]    The first and second lenses  12 ,  13  are configured to cooperatively form an image of an object. The first lens  12  essentially includes an optical portion  121  and a base portion  123 . The optical portion  121  is formed in a middle portion of the base portion  123 , and has a predetermined spherical or aspherical surface to participate in forming the object image. The base portion  123  is adapted for fixing the first lens  12  into the barrel  11 . The first lens  12  has a diameter approximately equal to a diameter of the receiving cavity  113  of the barrel  11 . Thus, when the first lens  13  is received in the barrel  11 , an outer periphery of the first lens  12  can abut against the inner circumferential wall  111  of the barrel  11  to prevent radial movements of the first lens  12 . The second lens  13  has a similar structure to the first lens  12  and includes an optical portion  131  and a base portion  133 . 
         [0018]    The spacer  20  is an annular cylinder, and has an outer diameter slightly less than the diameter of the receiving cavity  113  of the barrel  11 . The spacer  20  has an upper surface  201 , a lower surface  203  positioned on an opposite side to the upper surface  201 , a through hole  22  extending through a body of the spacer  20  and penetrating the upper surface  201  and the lower surface  203 , and an annular slot  23  defined in the upper surface  201 . The spacer  20  has an axial length/distance between the upper surface  201  and the lower surface  203 , which can be chosen according to a desired focal length. The through hole  22  of the spacer  20  has a diameter larger than the diameters of the optical portions  121 ,  131  of the first and second lenses  12 ,  13 , thus permitting light to pass therethrough. The slot  23  is defined between an outer circumference of the spacer  20  and an inner circumference of the spacer  20 . 
         [0019]    The adhesive/glue dots  31  can consist of a hardenable adhesive/glue such as an ultraviolet glue (UV glue) or a thermosetting glue. The adhesive/glue dots  31  are applied to the upper surface  201  of the spacer  20 , along the outer circumference of the upper surface  201 , and outside the slot  23 . The adhesive/glue dots  31  are dispensed in precisely measured amounts and are equally spaced. 
         [0020]    The first lens  12 , the spacer  20  and the second lens  13  are sequentially placed in the receiving cavity  113  of the barrel  11 , and the outer peripheries of the first lens  12 , the spacer  20  and the second lens  13  abut/bias against the inner circumferential wall  111  of the barrel  11  so as to restrain radial movements thereof. The base portion  123  of the first lens  12  abuts against the supporting surface of the stopper ring  115 . The spacer  20  is sandwiched between the first lens  12  and the second lens  13 , wherein the lower surface  203  of the spacer  20  abuts against the base portion  123 , the upper surface  201  of the spacer  20  abuts against the base portion  133  of the second lens  13 , and the through hole  22  is aligned with the optical portions  121 ,  131 . The second lens  13  is fixed to the spacer  20  and the inner circumferential wall  111  of the barrel  11  via the adhesive/glue dots  31 . Hence, the second lens  13  and the stopper ring  115  cooperatively secure the first lens  12  and the spacer  20  in the barrel  11 . 
         [0021]    Referring to  FIGS. 3 and 4 , a glue dispenser  40  configured for dispensing glue/adhesive dots  31  on the spacer  20  is shown. The dispenser  40  mainly includes a dispensing portion  41  and a piston portion  43 . The dispensing portion  41  is advantageously cylindrical to allow it to matingly match with the receiving cavity  113  of the barrel  11 . More specifically, the dispensing portion  41  preferably has a diameter approximately equal to the diameter of the receiving cavity  113  of the barrel  11  to facilitate a sliding clearance fit therebetween. The dispensing portion  41  includes a top side  411 , a bottom side  412 , and a cylindrical sidewall  413 . The bottom side  412  of the dispensing portion  41  is positioned opposite to the top side  411 . The dispensing portion  41  also has a main flow passage  415  and a plurality of feed flow passage  416 . The main flow passage  415  and the respective feed flow passage  416  are cooperatively used to transport flowable and hardenable adhesive/glue  30  to a plurality of chosen gluing locations (i.e., the positions of the adhesive/glue dots  31 ). The main flow passage  415  is defined generally centrally/axially inside the dispensing portion  41 . The main flow passage  415 , usefully, runs/extends perpendicular from the top side  411  toward the bottom side  412  but does not penetrate the bottom side  412  (i.e., glue is not permitted to reach the bottom side  412  in a central area of the lens module  10 ). The feed flow passages  416  communicate with a lower portion of the main flow passage  415  and radiate outwardly therefrom. The feed flow passages  416  respectively extend to a joint of the sidewall  413  and the bottom side  412  of the dispensing portion  41 . At such a joint, the respective feed flow passage  416  terminated and, thus, form a plurality of output ports  417 . Such output ports  417  communicate with ambient air to permit dispensing of adhesive/glue  30  therefrom. Each output port  417  is, advantageously, equally spaced from each adjacent port  417  (i.e., ports  417  are evenly and regularly spaced). The bottom side  412  of the dispensing portion  41  has an annular ring  419  projecting therefrom. The annular ring  419  has a configuration similar to the annular slot  23  of the spacer  20  for mating with the annular slot  23 . The piston portion  43  is axially movably placed in the main flow passage  415 , and liquid seals the main flow passage  415 . The piston portion  43  can be manually controlled by an operator or automatically controlled by a computer. The piston portion  43  should preferably be controlled by a computer. As such, the dispenser  40  would be able to precisely dispense a plurality of adhesive/glue dots  31 , with dot  31  having a predetermined amount of glue associated therewith. 
         [0022]    A method of assembling the lens module  10  includes the following steps: 
         [0023]    (1) providing a barrel  11 , having an inner circumferential wall  11  and a stopper ring  115 ; 
         [0024]    (2) placing a first lens  12  into the barrel  11  until the first lens  12  abuts on the stopper ring  113 , the first lens  12  including an optical portion  121  and a base portion  123  contacting with the stopper ring  113 ; 
         [0025]    (3) mounting a spacer  20  directly upon the first lens  12 , the spacer  20  (i.e., the spacer body) having a through hole  22 , a lower surface  202 , and an upper surface  201 , the through hole  22  aligning with the optical portion  121  of the first lens  12 , the lower surface  202  contacting the first lens  12 , and the upper surface  201  having an annular slot  23  defined therein; 
         [0026]    (4) placing a glue dispenser  40  into the barrel  11 , the glue dispenser  40  having a cylindrical dispensing portion  41  including a bottom side  412 , a plurality of output ports  417  and an annular ring  419 , the glue dispenser  40  being positioned with the bottom side  412  contacting the upper surface  201  of the spacer  20 , the annular ring  419  engaging the annular slot  23  of the spacer  20 , and the output ports  417  corresponding to an interface between the spacer  20  and the inner circumferential wall  111  of the barrel  11 ; 
         [0027]    (5) employing the glue dispenser  30  to synchronously dispense a plurality of adhesive/glue dots  31  on the upper surface  201  of the spacer  20  along an outer circumference thereof, the adhesive/glue dots  31  being of precisely dispensed in amount and equally spaced from an adjacent adhesive/glue dot  31 ; and 
         [0028]    (6) mounting a second lens  13  onto the upper surface  201  of the spacer  20  for attaching the second lens  13  to the upper surface  201  of the spacer  20  and the inner circumferential wall  111  of the barrel  11 , via the adhesive/glue dots  31 . 
         [0029]    To improve the optical performance of the lens module  10  repeat steps (2) to (6) to mount more optical members, such as lenses or filters, into the barrel  11 . 
         [0030]    It is to be understood that the adhesive/glue dispensed on the spacer  20  should preferably be a plurality of adhesive/glue dots  31 , the adhesive/glue also can be a plurality of adhesive/glue strips extending along the outer circumference of the upper surface  201  of the spacer  20 . Correspondingly, the output ports  417  of the dispenser  40  can be circular openings shaped according to the adhesive/glue dots  31 , or strip-shaped openings shaped in accordance with the adhesive/glue strips. 
         [0031]    It is to be understood that the annular ring  419  of the dispenser  40  can be divided into several portion instead of the one-piece ring in the preferred embodiment. 
         [0032]    In the foresaid exemplary embodiment, the spacer  20  has a slot  23  defined therein, the slot  23  is configured for receiving redundant adhesive/glue, and, thus, there is minimal risk of excess adhesive/glue, overflowing down the through hole  22  to pollute the lenses  12 ,  13 . In addition, the adhesive/glue dots  31  are synchronously dispensed to the spacer  20  with designated amount, and the distribution of the adhesive/glue dots  31  is determined by the corresponding distribution of the output ports  417  of the dispenser  40 . Therefore the method of assembling the lens module  10  is much more faster, and the distribution of the adhesive/glue dots  31  is relatively easy to control. 
         [0033]    It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.