Abstract:
An insertion type lens assembly for an optical system which connects a plastic lens and a plastic lens, a plastic lens and a glass lens, or a plastic lens and a barrel. A separation mold surface is located different sides, and a spacer is located between the lenses. The concentric contact plane is located at the inner periphery of the lens core or the sleeve. The vertical contact plane is located at the inner periphery of the lens core or the machining surface of the sleeve. Such that the present invention can avoid hairs on the separation mold surface and increases the precision of the shape of the surface of insert.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a lens assembly for an optical system and more particularly, to a lens assembly that connects a plastic lens to a plastic lens, a plastic lens to a glass lens, or a plastic lens to a barrel. A separation mold surface is set at different sides (outer sides, inner sides or an outer side and an inner side), and a spacer is located between the lenses. 
     BACKGROUND OF THE INVENTION 
     How to reduce factors of reducing the optical resolution and the precision of axial installation is the main issue of the present optical industry. In an optical system, a method of connecting two lenses together is shown in FIG.  1 . 
     A first lens  11  and a second lens  12  are connected with each other by the flat surfaces and their outer periphery are engaged with the barrel  13 . The axis of the first lens  11  and the axis of the second lens  12  can be located in alignment with each other when installing the lenses in the barrel by checking the degree of perpendicularity for the flat surfaces to the axes of the first and the second lenses  11 ,  12 , the degree of alignment of the axis of the barrel  13  to the outer peripheries of the first and the second lenses  11 ,  12 , the gap between the barrel  13  and the first and the second lenses  11 ,  12 , and the relative degree of alignment of the contact positions of the barrel  13  and the two lenses  11 ,  12 . 
     However, when the first and the second lenses  11 ,  12  includes a plastic lens, there will be some problems when manufacturing. A typical plastic lens is shown in FIG.  2  and consist of four parts in a mold, cavity side sleeve  21 , cavity  22 , core side sleeve  23  and core  24 . Generally, the concentric contact plane is designated to the position  25  and the vertical contact plane is designated to the position  26  or position  27 . This arrangement usually leads to some problems. 
     First, the precise of the shape of the product depends upon the mold and the cavity  22  and the core  24  are machined by two-axle precise lathe which has a precision to 0.1 um and the inner periphery of the barrel is made by way of grinding which has a precision to 1 um. If the positions  25 ,  26 ,  27  of the lens are pushed by the molds and if the gate is allowed to be protruded, then the lens can be made by lathe which has a precision up to 2-5 um as shown in FIG.  3 . If the positions are pushed by ejection pins  28  and D-shaped cut  29 , then electric discharge machining is used which has a precision up to 20 um. Therefore, the optical axes is not easily to be put in alignment with each other. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a lens assembly of an optical system and which can avoid the difference of optical axes between the outer periphery of lenses and barrel by way of connection between the lenses or between a spacer and a lens. This can increase resolution of the optical system. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a conventional lens assembly; 
     FIG. 2 shows a conventional lens mold; 
     FIG. 3 shows D-cutout of the conventional lens mold, and 
     FIGS. 4 to  17  show the first embodiment to the fourteenth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 4, in the first embodiment, two plastic lenses are connected with each other and a flat surface and co-axial surface of insert for controlling the distance between the lenses are involved in the side of the connection. The lens core  30  of the first lens  3  and the parting line of sleeve  31  are located at an outer side of the surface of insert  32 . The diameter D1 of the parting line of sleeve  31  and the lens core  30  are larger than the diameter D of the spacer  33 . The core lens  35  of the second lens  34  and the side of insert  36  are located at an outer side of the surface of insert  32 . The diameter D2 of the side of insert  36  is larger than the diameter D of the spacer  33 . The surface of insert  32  of the first lens  3  and the second lens  34  contact directly. The parting line of sleeve  31 , side of insert  36  of the first lens  3  and the second lens  34  are located at an outer side of the surface of insert  32  so that hairs on the periphery of the parting line of sleeve  31 , side of insert  36  of the first lens  3  and the second lens  34  can be avoided, and the precision of the shape of the surface of insert can be increased. 
     In the second embodiment, as shown in FIG. 5, the lens core  30  of the first lens  3  and the parting line of sleeve  31  are located at an outer side of the surface of insert  32 . The core lens  35  of the second lens  34  and the side of insert  36  are located at an outer side of the surface of insert  32 . The surface  301  for controlling the distance between the first lens  3  and the second lens  34  is separated by a spacer  302  which can be a SOMA to control the incoming light to obtain a good quality of image. The thickness of the spacer  302  is less than 0.25 mm. 
     In the third embodiment, as shown in FIG. 6, the lens core  30  of the first lens  3  and the parting line of sleeve  31  are located at an inside of the surface  301  for controlling the distance between the lenses. The core lens  35  of the second lens  34  and the side of insert  36  are located at an outer side of the surface of insert  32 . Hairs on the periphery of the parting line of sleeves  31 , side of insert  36  of the first lens  3  and the second lens  34  can be avoided and the assembly can be made in a stable manner. 
     In the fourth embodiment as shown in FIG. 7, similar to that of the third embodiment, the surface  301  for controlling the distance between the first lens  3  and the second lens  34  is separated by a spacer  302  and the thickness of the spacer  302  is less than 0.25 mm. 
     In the fifth embodiment as shown in FIG. 8, the lens core  40  of the first lens  4  and the parting line of sleeve  41  are located on the surface  43  for controlling the distance between the lenses of the side of insert  42 . The lens core  45  of the second lens  44  and the parting line of sleeve  46  are located at the inner side of the side of insert  42 . 
     In the sixth embodiment as shown in FIG. 9, the lens core  50  of the first lens  5  and the parting line of sleeve  51  are located at an outer side of the surface  54  for controlling the distance between the lenses of the side of insert  53  and the surface of insert  52 . The lens core  56  of the second lens  55  and the parting line of sleeve  57  are located at an inner side of the surface of insert  52 . 
     In the seventh embodiment as shown in FIG. 10, the lens cores  50 ,  56  of the first lens  5  and the second lens  55  and the parting line of sleeves  51 ,  57  are located at an outer side of the surface  54  for controlling the distance between the lenses of the side of insert  53  and the surface of insert  52 . The diameter D1 of the parting line of sleeve  51  and the lens core  50  of the first lens  5  are larger than the diameter D of the side of insert  53 . The diameter D2 of the parting line of sleeve  57  of the second lens  55  is larger than the diameter D of the side of insert  53 . 
     In the eighth embodiment as shown in FIG. 11, the lens core  60  of the first lens  6  and the parting line of sleeve  61  are located at an outer side of the surface  62 . The lens core  64  of the second lens  63  and the parting line of sleeve  65  are located at a horizontal inner side of the surface  67  for controlling the distance between lenses of the side of insert  66 . 
     In the ninth embodiment as shown in FIG. 12, the first lens  7  can be a plastic lens and the second lens  70  can be a glass lens which is connected to the first lens. The lens core  71  of the first lens  7  and the parting line of sleeve  72  are located at an outer side of the side of insert  73 . The diameter D1 of the parting line of sleeve  72  and lens core  71  of the first lens  7  are larger than the diameter D of the side of insert  73 . The surface of insert  74  of the first lens  7  and the second lens  70  may contact directly. 
     In the tenth embodiment as shown in FIG. 13, the first lens  8  is a plastic lens and the second lens  80  can be a glass lens which is connected to the first lens. The lens core  81  of the first lens  8  and the parting line of sleeve  82  are located at an outer side of the side of insert  83 . A spacer  84  is located between the side of inserts  83  to separate the first lens  8  and the second lens  80 , the thickness of the spacer  84  is less than 0.25 mm. 
     In the eleventh embodiment as shown in FIG. 14, the first lens  8  is a plastic lens and the second lens  80  can be a glass lens. The lens core  81  of the first lens  8  and the parting line of sleeve  82  are located on the surface  86  for controlling the distance between the two lenses of the surface of insert  85  and the side of insert  83 . 
     In the twelfth embodiment of the optical system as shown in FIG.  15  and includes a first lens  9 , a second lens  94  and the spacer of lens  90 . The first lens  9  is a plastic lens and connected to the spacer of lens  90 . The lens core  91  of the first lens  9  and the parting line of sleeve  92  are located on the surface of insert  93 . The first lens  9  is installed at its maximum diameter. The lens core  91  and the diameter D1 of the parting line of sleeve  92  are larger than the diameter D of the side of insert  93 . The second lens  94  is connected to the spacer of lens  90 , wherein the outer diameter of the second lens  94  is engaged with an inner diameter of the spacer of lens  90 . 
     In the thirteenth embodiment of the optical system as shown in FIG.  16  and includes a first lens  9 , a second lens  94  and the spacer of lens  90 . The first lens  9  is a plastic lens and connected to the spacer of lens  90 . The lens core  91  of the first lens  9  and the parting line of sleeve  92  are located at the outer side of the surface of insert  93 . The second lens  94  is engaged with the spacer of lens  90 , wherein the outer diameter of the second lens  94  is engaged with an inner diameter of the spacer of the lens  90 . 
     In the fourteenth embodiment of the optical system as shown in FIG. 17, and includes a first lens  9 , a second lens  94  and the spacer of lens  90 . The first lens  9  is a plastic lens and connected to the spacer of lens  90 . The lens core  91  of the first lens  9  and the parting line of sleeve  92  are located at the outer side of the surface of insert  93 . The second lens  94  may contact the spacer of lens  90  by the edge  95 . 
     It is to be noted that the present invention may change the position of the parting line of sleeve and the shape of the lenses to match the lenses. The concentric contact plane is located at the inner periphery of the lens core or the sleeve. The vertical contact plane is located at the inner periphery of the lens core or the machining surface of the sleeve. By this way, the shape precision of the mold can be increased and improves the stability of assembling. 
     While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.