Abstract:
A spacer for extending an image from a lens assembly of a camera comprises a hollow tube having a front engaging portion capable of being connected to the lens assembly and a rear engaging portion capable of being connected to the camera body; and a first lens installed in the tube; and a second lens installed in the tube and being spaced apart from the first lens. The tube is telescopic. This is achieved by causing that the tube has a plurality of sections or the tube has at least two sections which are threadedly engaged or a compressible and expandable snake like structure is installed between two sections of the tube so that the tube can be prolonged or compressed to adjust the whole length of the spacer. Furthermore the first lens and second lens are concave lenses or convex lenses which are symmetric or asymmetric.

Description:
FIELD OF THE INVENTION 
   The present invention relates to camera parts, and particularly to an optical spacer for extending an image traveling distance from a lens assembly to an image sensor of a camera. 
   BACKGROUND OF THE INVENTION 
   A typical schematic view of a conventional camera is showing in  FIG. 1 . The conventional camera structure includes a lens device  10  and a camera body  20  enclosing a circuit board  21 , an image sensor  22  and a receptacle portion  23  for containing the sensor  22 . In this conventional configuration, the lens device  10  includes a lens tube  11  with at least one piece of lens  12  inside the lens tube  11 , and the sensor  22  is mounted on the circuit board  21 . At an distal end of the lens tube  11 , the tube is connected with the camera body  20 , and the distance between the lens  12  and the sensor  22  is in close proximity. 
   According to the general optical imaging theory, a reflected light from an object captured by the lens device can be focused onto an optical sensor  22 , by a plurality of lenses inside the lens tube  11 . An optical sensitive sensor  22  can convert the focused lights into electrical currents. As the electrical current flowing into the semiconductor devices on the circuit board  21  through electrically wired connections, the electrical signals are post-processed and converted into digital data for displaying the reconstructed image on electronic display devices or storing into memory devices. 
   In the prior art the shape of the lens device  10  is configured as a small circular ring as illustrated in  FIG. 1 , meanwhile the camera body  20  is constructed in a cubic like shape to accommodate circuit board and electronic devices. In this configuration, the lens set  10  is attached to the camera body  20  and the lenses are designed to be very close to the sensor  22  for a compact camera body design and maintaining good quality of image. The camera systems have been used in many applications in our daily life, however there are cases requiring the lenses device  10  far away from the camera body  20  due to various design constraints in space. Most of the current used and produced cameras provide lens devices with short lengths neither be able to match the design constraints nor be able to meet the required product specifications. As a result, there are demands for novel designs to overcome the design constraints to extend the image traveling length. 
   The various objects and advantages of the present invention would be more obviously understood as we disclose the detailed description in conjunction with the appended figures. 
   SUMMARY OF THE INVENTION 
   Accordingly, the primary object of the present invention is to provide a spacer for extending an image from a lens assembly of a camera. The spacer is installed between the lens assembly having at least one lens therein for capturing an image and a camera body having an image sensor for converting the incident light into electrical signals. 
   To achieve above objects, a spacer is provided to be implemented between the lens assembly and sensor for extending the image of a camera. The spacer installed between the lens assembly and sensor will have at least one lens therein for capturing an image. The spacer comprises a hollow tube having a front engaging portion capable of being connected to the lens assembly and a rear-engaging portion capable of being connected to the camera body. A first lens and a second lens are installed within the spacer tube and separated from each other with a designed space in between. An axis of the first lens and an axis of the second lens are arranged approximately in parallel and are approximately vertical to an axis of the tube. The tube is telescopic. This is achieved by causing that the tube has a plurality of sections or the tube has at least two sections which are engaged by thread or a compressible and expandable snake like structure installed between two sections of the tube so that the tube can be prolonged or compressed to adjust the whole length of the spacer of the present invention. The first lens and second lens are concave lenses and may be symmetric or asymmetric or the first lens and second lens are concave lenses with symmetric or non-symmetric in arrangement. 
   Finally, in the present invention, a retaining unit is installed within the spacer tube. An optical filter glass is installed in the tube for filtering out of a predetermined light spectrum and can be positioned selected locations such as in front of the first lens, between the two lenses or behind the second lens. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a prior art camera structure including the lens assembly and a camera body. 
       FIG. 2  shows the spacer implemented between the lens assemble and a camera body according to first embodiment of the present invention. 
       FIGS. 3(A) ,  3 (B) and  3 (C) are schematic views for explaining the physical mechanisms of the present invention. 
       FIG. 4  is a schematic view of two double-face concave lenses inside the spacer according to the present invention. 
       FIG. 4(A)  is a perspective view about the spacer in  FIG. 4 . 
       FIGS. 5(A) and 5(B)  are schematic views showing some various designs of the first embodiment of the present invention. 
       FIG. 6  shows that in one application of the present invention, a retaining unit is installed in the tube and between two lenses. 
       FIGS. 7(A) to 7(C)  shows that an optical filter glass installed at different positions within the tube of the present invention. 
       FIGS. 8(A) to 8(C)  show a variety of designs of the first embodiment of the present invention, wherein the tube of the present invention is telescopic. 
       FIGS. 9(A) to 9(C)  shows the second embodiment of the present invention, where the first and second lenses are convex lenses. 
       FIG. 9D  is a perspective view about the spacer in  FIG. 9(A) . 
       FIG. 10  shows that in one application of the present invention, wherein a retaining unit is installed in the tube and between two lenses. 
       FIGS. 11(A) to 11(C)  show that a optical filter glass is implemented at different positions within the tube of the present invention. 
       FIGS. 12(A) and 12(B)  are schematic views showing some variations about the third embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In order to assist those skilled in the art realizing the present invention, the detailed description of the invention is disclosed in this section. However, the descriptions and the appended drawings are only used to cause those skilled in the art to understand the objects, features, and characteristics of the present invention, but not to be used to confine the scope and spirit of the present invention defined in the appended claims. 
   Referring to  FIG. 2 , the first embodiment about the spacer of the present invention is illustrated. The spacer of the present invention is in a hollow tube  30  with two lenses, a first lens  41  and a second lens  42 , installed therein. Generally, the tube  30  is a cylindrical rigid structure. The tube  30  has a front engaging portion  31  and a rear-engaging portion  32 . The front engaging portion  31  serves as for connecting to a lens assembly  50  by for example, threads, or buckling. The rear-engaging portion  32  serves as for connecting to a camera body  51  by for example, threads or buckling. In  FIG. 2 , the front-engaging portion  31  and rear-engaging portion  32  are illustrated by threaded portions, however these are not used to confine the scope of the present invention, other structures having the functions of engaging two different portions are also within the scope and spirit of the present invention. 
   The first lens  41  and the second lens  42  are spaced apart with a distance d. In the embodiment, the first lens  41  and the second lens  42  are all concave lenses with a flat surface at one side facing to another lens. Referring to  FIGS. 3(A) ,  3 (B) and  3 (C), the physical mechanism is illustrated for the description of the present invention. Firstly, an image is captured by the lens assembly  50  with lens set  501  therein and thus the image converges and then is focused at the backside of the lens assembly  50 . In the prior art, the image will incident into an image sensor  511  (such as a charge coupling device (CCD) or a CMOS arrays) on a circuit board  512  of the camera body  51 , referring to  FIG. 3(A) . If the lens assembly  50  is shifted to a farther place as illustrated in  FIG. 3(B) , the image can be focused to the image sensor  511  so that the image will disperse and the image sensor  511  only captures a blurred image. However if we add lenses into the tube  30 , as illustrated in  FIG. 3(C) , the originally converging image will pass through the first lens  41  and then will be expanded to become parallel light beam to be transferred through the distance d. As the parallel light beam passes through the second lens  42  and then is further expanded by the second lens  42  so that the second lens  42  will enlarge the image. Finally, the second lens  42  will incident into the image sensor  511 . As a result, the image projected into the image sensor  511  will have a desired coverage without reduction. Thus from above description, it is known that by adding the present invention in between the camera body  51  and the lens assembly  50 , the image can be retained with a large coverage on the image sensor. 
   Those skilled in the art should understand that above mentioned structure is only an ideal case for illustrating the use of the spacer of the present invention, while in the present invention, the distance of the two lenses is not confined. Moreover, the curvatures of the first lens  41  and second lens  42  are not confined to have a perfect form which can retain the image to have a parallel beams. However the output light beam out of the first lens  41  may be not a parallel beam if the curvature of the first lens  41  is not an ideal one. Although this will make the image quality not as good as compare to the performance of the former example, all these non-ideal cases are also within the scope and spirit of the present invention. 
   Referring to  FIG. 4 , it shows that in the present invention, each of the two lenses, the first lens  41  and second lens  42 , is a double face concave lens. Although these lenses cannot form a parallel beam there between, this example is still within the scope of the present invention. 
   Moreover, referring to  FIGS. 5(A) and 5(B) , in the present invention, the two concave lenses are not limited to be symmetrical in arrangement, as illustrated in the drawings, in  FIG. 5(A) , the two concave lenses, the first lens  41  and second lens  42  are asymmetrical. The curvature of the first lens  41  is greater than that of the second lens  42 . In  FIG. 5(B) , the curvature of the second lens  42  is greater than that of the first lens  41 . 
   Referring to  FIG. 6 , another variation of the present invention is illustrated. It is illustrated that in the present invention, a retaining unit  8  is installed between two the first lens  41  and second lens  42  so as to retain the two lenses  41 ,  42  within a fixed distance. The retaining unit can be a partial or a whole round between the two lenses. 
   Referring to  FIGS. 7(A) ,  7 (B) and  7 (C), another variation of the present invention is illustrated. It is illustrated that a optical filter glass  7  is installed within the tube  30  for filtering out undesirable section of light spectrum to maintain an image with preferred quality. The filter  7  can be installed at different positions of the tube. In  FIG. 7(A) , it is showing that the optical filter glass  7  is installed between the lens assembly and the first lens  41 . In  FIG. 7(B) , it is illustrated that the optical filter glass  7  is installed between the first lens  41  and the second lens  42 . In  FIG. 7(C) , it is illustrated that the optical filter glass  7  is installed behind the second lens  42 . Conventionally, the optical filter glass  7  is added on a front surface of the first lens  41 , the coating layer of the filter is exposed to outside and its surface is prone to various damages due to careless handling by users. If the filer glass  7  of the present invention is located behind the first lens  41 , above-mentioned problems can be avoided. 
   Referring to  FIGS. 8(A) to 8(C) , some variations about the first embodiment of the present invention are illustrated. In this embodiment, those identical to the above embodiment will not be further described herein. Only those different from above embodiment are described. In this second embodiment, it is illustrated that the tube  30  is a telescopic tube. There are many different forms that can achieve above-mentioned object. In  FIG. 8(A) , it is shown that the tube  30  has a plurality of sections, which can be prolonged or shortened so as to adjust the distance between the camera body  51  and the lens assembly  50 . In  FIG. 8(B) , it is shown that the tube  30  has two sections, which are threading engaged so that the tube  30  is telescopic by screwing the one section with respect to another one. Referring to  FIG. 8(C) , a compressible and expandable snake like structure is installed between two sections of the tube  30  such that the tube  30  can be prolonged or compressed to adjust the whole length of the spacer of the present invention. The adjustment of the length of the tube  30  has the advantages of adjusting the distance between the camera body  51  and lens assembly  50  so as to have a desired arrangement to be accepted by the user, and moreover, the adjustment of the length of the tube  30  will adjust the focusing of the lenses within the tube  30  so as to achieve a desirable image. 
   It should be noted herein that the arrangements in  FIGS. 8(A) to 8(C)  are suitable to be used with the lenses disclosed in  FIGS. 2 to 5  and the retaining unit  8  in  FIG. 6  and optical filter glass  7  in  FIG. 7  are also suitable to be used within the arrangements of  FIGS. 8(A) to 8(C) . This can be understood by those skilled in the art and thus the detail will not be further described herein. 
   With referring to  FIGS. 9(A) to 9(C) , the second embodiment of the present invention is illustrated. In this embodiment, those identical to the above embodiments will not be further described herein. Only those different from above embodiment are described. In this embodiment, the first lens  61  and second lens  62  are convex lenses, which are arranged within a tube  3 . The tube  3  is identical to those illustrated in  FIGS. 1 to 8  and thus the details will not be further described herein. It is illustrated in the drawing that a parallel beam incident the first lens  61  will be focused to a focus point and then expands after traveling out of the focus point. Then the beam travels through the second lens  62  so as to be further focused by the second lens  62 . 
   In  FIG. 9(A) , the input image carried by the light beam at the light side has a coverage equal to that in the output side. A perspective view about the spacer in  FIG. 9(A)  is illustrated in  FIG. 9(D) . However, if we adjust the second lens  62  to move leftwards, as illustrated in  FIG. 9(B) , it is illustrated that the image is enlarged. If we move the second lens  62  rightwards, as illustrated in  FIG. 9(C) , it is illustrated that the image is reduced after passing through the second lens  62 . 
   Referring to  FIG. 10 , another application of the present invention is illustrated. It is illustrated that in the present invention, a retaining unit  8 ′ is installed between two the first lens  61  and second lens  62  so as to retain the two lenses  61 ,  62  are a fixed distance. The retaining unit can be a partial or a whole round between the two lenses. 
   Referring to  FIGS. 11(A) ,  11 (B) and  11 (C), another application of the present invention is illustrated. It is illustrated that a optical filter glass  7 ′ is installed within the tube  30  for filtering the undesired light spectrum so as to have an image of preferred quality. However the filter  7 ′ can be installed at different positions inside the tube. In  FIG. 11(A) , it is shown that the optical filter glass  7  is installed between the lens assembly and the first lens  61 . In  FIG. 11(B) , it is illustrated that the optical filter glass  7 ′ is installed between the first lens  61  and the second lens  62 . In  FIG. 11(C) , it is illustrated that the optical filter glass  7 ′ is installed behind the second lens  62 . 
   Likewise, referring to  FIGS. 12(A) and 12(B) , in the present invention, the two concave lenses are not limited to be symmetrical, as illustrated in the drawings, in  FIG. 12(A) , the two convex lenses, the first lens  61  and second lens  62  are asymmetrical. The curvature of the first lens  61  is greater than that of the second lens  62 . In  FIG. 12(B) , the curvature of the second lens  62  is greater than that of the first lens  61 . 
   As described in the above second embodiment, in the second embodiment, it the tube  30  is a telescopic tube. There are many different forms, which can achieve above-mentioned object. For example, the tube  30  has a plurality of sections which can be prolonged or shortened so as to adjust the distance between the camera body  51  and the lens assembly  50 ; or the tube  30  has two sections which are threaded engaged so that the tube  30  is telescopic by screwing the one section with respect to another one; or a compressible and expandable snake like structure is installed between two sections of the tube  30  so that the tube  30  can be prolonged or compressed to adjust the whole length of the spacer of the present invention. 
   While the present invention has been described in terms of what are presently considered to be the most practical and preferred embodiment. It is to be understood that the present invention need not to be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims that are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.