Abstract:
A LED light source used in a scanner is disclosed, and particularly a series of lenses employed to condense the LED light on the front and rear sides and disperse the LED light to the left and right sides. LED compared with CCFL employed as a light source can improve the problem of high power consumption, warm-up, and the limits of lifetime. Furthermore, the light through the lens extends the range of the left and right sides on a scanned material. Therefore, the amount of the LEDs decreases, than that skilled in the art used a large number of LEDs for obtaining a smoother field of light, and achieve low power consumption.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a scanner with an LED light source and particularly to an LED light source with a condensing lens that condenses the LED light from the front and rear sides and disperses the LED light on the left and right sides.  
           [0003]    2. Description of the Prior Art  
           [0004]    In general, a scanner utilizes the light source needed for scanning to produce and project the light onto the material to be scanned. The image of the scanned material is then received and transmitted as reflected light from the scanned material. The image is then captured and the data of the captured image is conveyed to a personal computer etc. for processing. The light source used to project the scanned material generally produces a linear light, which the brightness of light remains unchanged during scanning. A large variation of brightness is forbidden to ensure the needed accuracy in the brightness of the captured image. Especially when scanning a colorful image, the light source must be constantly stable white light source, so that the captured image achieves a high quality in brightness, stability of color, and similarity in imaging.  
           [0005]    Referring to FIG. 1A and FIG. 1B, the conventional art is using a CCFL  10  (Cold Cathode Fluorescent Lamp) or a linear plurality of a LED light source as the scanning light source. When the CCFL is utilized as a scanning light source, the illumination is isotropic  16 . The illumination is a spotlight  14  by a pillar made of a concave surface or a mirror  12 , (as shown in FIG. 1A and 1B.) and projected onto the scanned material. In addition, the CCFL  10  must warm-up before becoming stable for use in capturing the image of the material scanned. Furthermore, the lifetime of CCFL  10  is generally about ten thousand hours and produces a large amount of heat and energy due to the low efficiency of CCFL  10  illumination thus wasting a large amount of energy. Therefore, the CCFL  10  has an inherent defect in time and power consumption.  
           [0006]    On the other hand, a plurality of LED  22 , used as a light source for scanning, broadens the CCFL  10  limitations of life expectancy to an average of about one hundred thousand hours and effectively improves the warm-up duration of the scanning light source. Thus a plurality of LED  22  achieves convenience after turning on a scanner by being able to instantly scan a document. However the physical characteristic of the LED  22  is a forward dispersing and circular light source which the brightness decreases from the center to the edges, as shown in FIG. 2A. Hence, the LED  22  as a scanning light source that is tightly arranged in a line to avoid the inherent physical defects of the LED  22  light sources. Then, a pillar of waveguide assembly is mounted onto the LED  22 , in order too converge the LED light in a front and rear direction, as shown in FIG. 2B and FIG. 2C. Hence the light produced by the LED  22  overlap with each other, and the brightness increases to reach the needed scanning light which is bright enough and remain unchanged with time, as shown in FIG. 2D. The LED  22  has a high luminescence efficiency to avoid producing a large amount of heat and energy like the CCFL  10 . Nevertheless, a plurality of LED  22  used as a scanning light source causes to reduce inefficiently in the necessary power for illumination.  
           [0007]    Hence, in order to achieve lower power consumption, an extended lifetime, and too begin scanning without any warm-up time, it is an important object to provide a needed light source for scanning.  
         SUMMARY OF THE INVENTION  
         [0008]    The conventional arts mentioned above, can&#39;t provide a scanning light source with a lower power consumption, longer lifetime, and to begin scanning without any warm-up time. In accordance with the present invention, the front and rear sides of the LEDs light is condensed by lenses to increase the brightness and the light of the left and right sides thereof is simultaneously dispersed to form a linear light source. For this reason, the amount of LEDs is efficiently reduced.  
           [0009]    It is another object of this invention to efficiently decrease the amount of the LEDs needed by utilizing lenses to condense the LEDs light in the front and rear, and disperse the LED light on the left and right sides.  
           [0010]    It is a still another object of this present invention to reduce the cost price of LEDs by utilizing lenses that condense the LEDs light on the front and rear sides, and then disperse the LEDs light on the left and right sides.  
           [0011]    It is another object of this invention to provide a scanning light source by using LEDs with a longer lifetime, and decreasing the limits of a scanner due to the scanning light source.  
           [0012]    It is a still another object of this present invention to provide an LED scanning light source that has the advantage of scanning without time allotted for warm-up, thus increasing efficiency in scanning time.  
           [0013]    It is another object of this invention to form a plane light source on the light field corresponding to the different needs, by utilizing lenses that condense the LED light on the front and rear sides and then disperse the LED light on the left and right side.  
           [0014]    In accordance with the above-mentioned objects, the present invention provides a lens assembly that condenses the LED light for the front and rear sides, then disperses the LED light on the left and right side, and a method for manufacturing the same. The present invention employs a lens assembly for condensing the light in the front and rear side and dispersing the light on the left and right sides. Hence, this prevent invention decreases the limit of a scanners lifetime, and provides a scanning light source without the need to warm-up thus preventing the waste of time. Furthermore, the lens assembly is employed to increase brightness by condensing the light on the front and rear side, and broadening the range of illumination on the left and right sides to arrange the LEDs loosely. For this reason, the needed distance of each LEDs is broadened. In the same scanning width, the needed amount of LEDs can be decreased, the cost of the LEDs can be reduced, and further the power consumption of the scanning light source can be substantially decreased. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understand by reference to the following detailed description, when taken in conjunction with the accompanying drawings, where in:  
         [0016]    [0016]FIG. 1A is a top view of a CCFL scanning light source;  
         [0017]    [0017]FIG. 1B is a side view of a CCFL scanning light source;  
         [0018]    [0018]FIG. 2A is a diagram of brightness varies with position in a plane perpendicular to illuminating direction of LED;  
         [0019]    [0019]FIG. 2B is a top view of LEDs as a scanning light source in those conventional arts;  
         [0020]    [0020]FIG. 2C is a side view of LEDs as a scanning light source in those conventional arts;  
         [0021]    [0021]FIG. 2D is a diagram of brightness of LEDs as a scanning light source varies with position perpendicular to illuminating direction of LED in those conventional arts;  
         [0022]    [0022]FIG. 3A is a top view of the related position of a white light LED mounted on a printed circuit board;  
         [0023]    [0023]FIG. 3B is a side view of the related position of a white light LED mounted on a printed circuit board;  
         [0024]    [0024]FIG. 3C is a diagram of power terminal and ground terminal of a LED connect with power supply controlled by ASIC;  
         [0025]    [0025]FIG. 4A is a top view of a circular cylinder;  
         [0026]    [0026]FIG. 4B is a cross-sectional view of a circular cylinder taken along line  4 B- 4 B of FIG. 4A;  
         [0027]    [0027]FIG. 4C is a diagram of a symmetrical saddle-shaped lens;  
         [0028]    [0028]FIG. 4D is a top view of a symmetrical saddle-shaped lens;  
         [0029]    [0029]FIG. 4E is a cross-sectional view of the center of the symmetrical saddle-shaped lens taken along  4 E- 4 E of FIG. 4D before amend thickness;  
         [0030]    [0030]FIG. 4F is a cross-sectional view of the center of the symmetrical saddle-shaped lens taken along  4 E- 4 E of FIG. 4D after amended thickness;  
         [0031]    [0031]FIG. 4G is a side view of the symmetrical saddle-shaped lens before amend thickness;  
         [0032]    [0032]FIG. 4H is a side view of the saddle-shaped lens after amended thickness;  
         [0033]    [0033]FIG. 4I is a side view of the symmetrical saddle-shaped lens with the plurality triangle cone protruding nicks;  
         [0034]    [0034]FIG. 4J is a top view of the symmetrical saddle-shaped lens with the plurality triangle cone protruding nicks;  
         [0035]    [0035]FIG. 4K is a side view of the symmetrical saddle-shaped lens with the plurality triangle cone protruding nicks;  
         [0036]    [0036]FIG. 4L is a diagram of a light passing through the bottom protruding nicks of the symmetrical saddle-shaped lens with the plurality triangle cone protruding nicks;  
         [0037]    [0037]FIG. 5A is a foot view of the symmetrical saddle-shaped lens with four thin cylinders mounted on four edges of the symmetrical saddle-shaped lens;  
         [0038]    [0038]FIG. 5B is a side view of the symmetrical saddle-shaped lens with four thin cylinders mounted on four edges of the symmetrical saddle-shaped lens;  
         [0039]    [0039]FIG. 5C is a side view of the symmetrical saddle-shaped lens with four thin cylinders mounted on four edges of the symmetrical saddle-shaped lens which is mounted on a printed circuit board;  
         [0040]    [0040]FIG. 5D is a top view of the symmetrical saddle-shaped lens with four thin cylinders mounted on four edges of the symmetrical saddle-shaped lens which is mounted on a printed circuit board;  
         [0041]    [0041]FIG. 6A is a diagram of the light field of the light of a LED through a waveguide pillar and through a saddle-shaped lens;  
         [0042]    [0042]FIG. 6B is a diagram of the overlapping light field of a plurality of LEDs through a waveguide pillar and through a saddle-shaped lens;  
         [0043]    [0043]FIG. 7A is a top view of the related position of RGB LED mounted on a printed circuit board;  
         [0044]    [0044]FIG. 7B is a diagram of power terminal and ground terminal of RGB LED connected with power-supply which controlled by ASIC; and  
         [0045]    [0045]FIG. 8A to FIG. 8D is a diagram with different arrangement of LEDs respectively. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0046]    Some sample embodiments of the invention will now be described in greater detail. Nevertheless, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the present invention is expressly not limited expect as specified in the accompanying claims.  
         [0047]    Then, the components of the different elements of the scanning light source are not shown to scale. Some dimensions are exaggerated so that the related components and meaningless portions are drawn to provide a more clear description and comprehension of the present invention.  
         [0048]    First, a direction of left and right sides of LED is along a direction of a line of LEDs and a direction of front and rear sides thereof is perpendicular to a direction of a line of LEDs.  
         [0049]    Referring to FIG. 3A and FIG. 3B, one preferred embodiment of this invention employs a bar printed circuit board (PCB)  30 , the length of the PCB is greater than about 216 mm and the width of the PCB is greater than about 2 mm. Due to the lack of white Light Emitting Diode (LED) of a most left white LED  32  at the left side, and a most right white LED  32  at the right side, the attenuation of brightness with a distance from the white LED  32  is greater in two sides of filed of the LED light. Therefore, the distance a between the left (or right)end of PCB  30  and the most left (or right) white LED  32  must be shorter than a half of distance  8  between the white LED  32  each other. In this present invention, a white LED  32  is mounted at a position  34  that is about 8 mm away from the left end of PCB  30 , and others is mounted at the PCB  30  by an interval of about 40 mm until a position  36  that is about 8 mm away from the right end of PCB  30 . Consequently, total of six white LED  32  is mounted in the PCB  30 . A parallel circuit  42 ,  44  is arranged in the PCB  30  for connecting respectively all power terminal  38  and ground terminal  40  of white LED  32 , as shown in FIG. 3C. Then, a conducting wire  46 ,  48  connects the parallel circuit  42 ,  44  that connects respectively all power terminals  38  and ground terminals  40  of total white LED  32  to a power supply  102  for controlling the brightness of white LED  32 .  
         [0050]    A ring like cylinder is selected from the group consisting of PMMA (Methacrylic resin) and PC (Polysulfone), that the diameter of cylinder  52  is about 6 mm and the inner diameter of the ring  54  is about 18 mm, as shown in FIG. 4A and FIG. 4B. A symmetrical shape of a saddle lens is obtained by cutting along the cutting line  56 ,  58 , and  60 . The crossed-section of the symmetrical shape of a saddle lens  104  is an arc. The thickness of the central portion thereof is about 0.9 to 3 mm, the thickness of two edges thereof is about 3 to 6 mm and the length thereof is about 6 to 12 mm, and the bottom and two edges thereof are plane surfaces, as shown in FIG. 4C.  
         [0051]    Referring to FIG. 2A, the characteristics of an LED light is a circular light source that forwardly emits light, which the brightness thereof decreases progressively outward. The LED light converts to a linear light source as required by a scanning light source with the symmetrical shape of a saddle lens  104  that condenses the LED light from the front and rear sides and disperses the LED light on the left and right sides. Furthermore, the profile of the symmetrical shape of a saddle lens  104  is narrower in central portion  62  and wider in two edge portions  64 , as shown in FIG. 4D. Therefore, the converging area of the central portion  62  of light is smaller than the converging area of two edge portions  64 , and the difference of brightness between the central portion of light and two edge portions of light is reduced. Thus, it provides a more proper scanning light source.  
         [0052]    Four thin columns  72 , with a diameter about 2 mm, are mounted on the four corners of the bottom of plate  70  of the symmetrical shape of a saddle lens  104 , as shown in FIG. 5A and FIG. 5B. Then, the symmetrical shape of a saddle lens  104  that four thin columns  72  have been mounted thereon is mounted on the PCB  30  upon a corresponding white LED  32  as center. In this manner, each white LED  32  is one-to-one with each symmetrical shape of the saddle lens  104  without contact or protection from an uneven PCB, as shown in FIG. 5C and FIG. 5D. Thus, the field of LED light  82  through the symmetrical shape of a saddle lens  104  is smoother than the field of LED light  84  through a pillar of waveguide assembled in the direction of left and right, as shown in FIG. 6A. On the premise that the lowest brightness of the scanning light source is larger than 60% of the highest brightness, the necessary amount of LED overlapping light field  86  with a symmetrical shape of a saddle lens  104  is less than the necessary amount of LED of overlapping light field  88  with a pillar of waveguide assembly, as shown in FIG. 6B.  
         [0053]    The difference of brightness between the center and edge of the field of light is further reduced by and emended by the curvature of the center and edge of the symmetrical shape of a saddle lens  104 . The central portion  62  of the symmetrical shape of a saddle lens  104  is polished thin to reduce the curvature of the central portion  62  in the direction of front and rear. So the efficiency of the converging light of the central portion  62  is weaker than at the edge, as shown in FIG. 4E and FIG. 4F. Furthermore, the curvature of the central portion  62  in the direction of the left and right is increased simultaneously by the above-mentioned polishing process, and so the efficiency of the dispersing light of the central portion  62  is stronger than at the edge, as shown in FIG. 4G and FIG. 4H. By reducing the efficiency of the converging light of the central portion  62  in the front and rear direction, and increasing the efficiency of the dispersing light of the central portion  62  in a left and right direction, the whole efficiency of the converging light of the central portion  62  is weaker than the edge portions  64 . In this manner, the difference of brightness between the center and the edge of the field of light through an emended shape of a saddle lens  106  reduces further.  
         [0054]    Furthermore, a preferred embodiment of the saddle lens is the saddle lens  10  with plurality triangle cone protruding nicks  112 . In a preferred embodiment, the height of the triangle cone protruding nicks  112  is 0.5 mm (mini-meter), and the bottom area is 0.5 mm (mini-meter)×0.5 mm ( mini-meter), as shown in FIG. 41. FIG. 4J is a top view of the symmetrical saddle-shaped lens  110  with the plurality triangle cone protruding nicks  112 . FIG. 4K is a side view of the symmetrical saddle-shaped lens  110  with the plurality triangle cone protruding nicks  112 .  
         [0055]    As the above mentioned, the characteristic of the LED light is a circular light source, as well as emits forwardly, and the brightness thereof decreases progressively outward. The LED light converts to a linear light source that fits to be a scanning light source by the symmetrical shape of a saddle lens that condenses the light of the LEDs for front and rear sides and disperses the light of the LEDs on left and right sides. Furthermore, the profile of the symmetrical shape of a saddle lens is narrower in central portion and wider in two edge portions. Therefore, the converging area of light of the central portion is smaller than the converging area of two edge portions, and the difference of brightness between the central portion of light and two edge portions of light reduces. In a light passing through the bottom protruding nicks  112  of the symmetrical saddle-shaped lens  110  with the plurality triangle cone protruding nicks  112 , the incident angle θ i  diverges the refraction angle θ j  with the light refraction, thereby the difference of brightness between the central portion of light and two edge portions of light reduces greatly, as shown in FIG. 4L. Thus, the saddle lens  110  with plurality triangle cone protruding nicks  112  provides more proper scanning light source.  
         [0056]    Another preferred embodiment according to this present invention replaces the above-mentioned white LED  32  with a RGB mixture-light LED  90  to mount at position  34 , about 8 mm away from the left end of PCB  30 . Others are mounted at the PCB  30  by an interval of about 40 mm until a position  36  is about 8 mm away from the right end of PCB  30 , as shown in FIG. 7A. The power terminal and ground terminal of the RGB mixture-light LED  90  are connected to the power supply  102  respectively, for supplying a needed power of the RGB mixture-light LED  90 . An ASIC (Application Specific Integrated Circuit)  100  is employed to connect with the power supply  102  for controlling the brightness of each color of the RGB mixture-light LED  90  to provide single color or other mixed color, as shown in FIG. 7B. Four thin columns  72  are mounted on the four corners of the bottom plate  70  of lens  104  or  106 . Then, the symmetrical shape of a saddle lens  104  or the emended shape of a saddle lens  106  is mounted on PCB  30  upon the RGB mixture-light LED  90  as center by four thin columns  72  and without contact. The light of the RGB mixture-light LED  90  is fixed to a linear field of light and mixed with a white light or other colors of demand.  
         [0057]    The type of LED in this present invention is unlimited to the white LED or the RGB mixture-light LED, and can be any mixture or type of LED as demanded.  
         [0058]    The arrangement of the module of LEDs in this present invention is not only a line, as shown in FIG. 8A, but also sideways arrangement of two lines of LEDs, a matrix, a crisscross matrix, and so on, as shown in FIG. 8B to FIG. 8D. The FIG. 8D shows a sideways matrix that the LEDs are arranged at 45-degree angles, but it is not limit the arrangement of the LEDs at 45-degree angles, and the the LEDs are arranged at any angles of demand. That is to say, the distance between a LED of a line of the LEDs and a first nearest LED of a adjacent line may be not equal to the distance between the LED of the line of the LEDs and a second nearest LED of the adjacent line. Therefore, the different arrangement of the LEDs can provide a light source with a different shape of demand.  
         [0059]    According to the preferred embodiments, this invention discloses a plurality of lenses employed to condense the front and rear side of LED light and disperse the LED light on the left and right side as used in a scanner. The above-mentioned scanning light source that compares with CCFL can improve the warm-up problem and the limited lifetime to increase the efficiency in time and decreasing the limit of the lifetime of the scanner. Furthermore, the field of light through the above-mentioned lens is fixed to a linear field of light and reduces the difference of brightness between the central portion and the edge portion of light. Hence, compared with using a pillar of waveguide assembly in the conventional art, this present invention provides a preferred scanning light source and decreases the necessary amount of LED to reduce the cost price of the LEDs. For example, the power of a LED is about 0.15 Watts, and so the total power of LED in this preferred embodiment is about  0 . 90  Watts. Hence total power of the LED in this preferred embodiment is less than 3 to 6 Watts of CCFL. In comparison to the conventional art the preferred embodiment archives low power consumption.  
         [0060]    Although specific embodiments have been illustrated and described, it will be obvious to those conventional art that various modifications may be made without departing from what is intended to be limited solely by the appended claims.