Patent Publication Number: US-2003222569-A1

Title: Light source for condensing light

Description:
[0001] This application claims the benefit of Taiwan application Serial No. 091111909, filed Jun. 3, 2002.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The invention relates in general to a light source, and more particularly to an illumination with a function of condensing light.  
       [0004] 2. Description of the Related Art  
       [0005] General scanners include at least a scanning platform, an illuminating device, and a stepping motor. The illuminating device is for scanning papers on the scanning platform; and the stepping motor is for driving the illuminating device gradually to move during the scanning process. The illuminating device comprises a light source, a lens, and a sensitized component. When scanning a paper, the light source provides light beams to illuminate the paper. The light beams reflected from the paper are collected and focused to form a duplicated image on the sensitized component. The component can get a partial image of the whole paper. After that, the stepping motor drives the illuminating device to move gradually to scan the portion which is not scanned yet. After all images are gathered together by the scanner, the whole image of the paper can then be revealed.  
       [0006] Referring to FIG. 1A, it illustrates a lateral view of a light source applied in general scanners. In FIG. 1A, a light source  102  is a tubular lamp, which has a radiating area  101 , and a penetrable layer  109  with even thickness. The radiating area, which is covered in the light source  102  by the penetrable layer  109 , is for supplying light. The penetrable layer  109  is provided with an inner tube  108  and an outer tube  110 . When the central axis L of the light source  102  is set as a base, an inner diameter a and an outer diameter b respectively corresponding to the inner tube  108  and the outer tube  110  are determined. The value of the outer diameter b is bigger than the inner diameter a, and the even thickness of the transparent layer is (b-a). In addition, the tubular lamp can be a cold cathode fluorescent lamp (CCFL).  
       [0007] Referring to FIG. 1B, it illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  1 B- 1 B vertical to the central axis L in FIG. 1A. In FIG. 1 B, the central axis L of the light source  102  is normally parallel to the surface of a paper  104 , i.e. the central axis L is parallel to the scan line on the paper  104 . The cross section of the inner tube  108  and the cross section of the outer tube  110  are two concentric circles having the central axis L as the same axle center. Namely, the cross sections of the inner tube  108  and the outer tube  110  have the same cross-section curvature.  
       [0008] Taking the whole illumination of the light source  102  as l, the beams of light provided by the radiating area  101  penetrate the penetrable layer  109  in the way of 360-degree divergent dispersion and emit outside. The scanned pixel  106 , which is on the paper  104  illuminated by the light source  102 , is taken as an example. Since the angle of the light beams illuminating on the scanned pixel  106  is Θ, the effective surface measure of the inner tube penetrated by illuminating beams on the scanned pixel  106  is (Θ/2 n) of the surface measure of the whole inner tube; and the illumination on the scanned pixel  106  is l*(Θ/2 n), that is also called the luminance of the scanned pixel  106 . If the luminance of the scanned pixel  106  (i.e. the illumination on the scanned pixel  106 ) can be increased, then the luminance of the whole scanned image can then be raised, and the quality of the scan can be raised also. Additionally, the time of exposure for a sensitized component can be shortened, and thus the scanning time can be shortened as well.  
       [0009] Furthermore, during the process of forming the image, since optical path differences can cause the problem of decreased light, the luminance around the two ends of a tubular light source is lower than the luminance of the middle part of the light source. Therefore, the luminance of the middle part of the image collected by the sensitized component is higher than that on the two sides of the image. Hence, the scanning quality is influenced extremely.  
       SUMMARY OF THE INVENTION  
       [0010] It is therefore an object of the invention to provide a light source with the function of condensing light. The effect of condensing light can be achieved by the design that results in the cross-section curvature of the outer tube of a condensing layer being greater than the cross-section curvature of the inner one. The luminance of the whole image can be improved by increasing the illumination coming from the light source on the scanned pixel. In addition, the time of exposure for a sensitized component can be shortened, and the time required for the scanning process can also be shortened.  
       [0011] The invention achieves the above-identified objects by providing a light source with the function of condensing light. The light source, which is provided with a central axis, comprises a radiating area, a penetrable layer, and a condensing layer, wherein [he radiating area is for providing light and the penetrable layer is for enabling the light to penetrate through to the outside. The penetrable layer consists of a first inner tube and a first outer tube. Any cross section, which is vertical to the central axis, of the first inner and outer tubes has the same first cross-section curvature. The condensing layer couples to the penetrable layer and together covers the radiating area inside the light source. The condensing layer consists of a second inner tube and a second outer tube. The second inner tube couples with the first inner tube, and the cross-section curvature of any cross section, which is vertical to the central axis, of the second inner tube is the same as the first cross-section curvature. The second outer tube couples with the first outer tube. The cross section, vertical to the central axis, of the second outer tube has at least a second cross-section curvature, and the second cross-section curvature is greater than the first one. Thus, the light can be condensed outside the condensing layer. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012] Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The description is made with reference to the accompanying drawings in which:  
     [0013]FIG. 1A illustrates a lateral view of a light source applied in general scanners;  
     [0014]FIG. 1B illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  1 B- 1 B vertical to the central axis L in FIG. 1A;  
     [0015]FIG. 2A illustrates a lateral view of a light source with a function of condensing light according to the preferred embodiment 1 of the invention;  
     [0016]FIG. 2B illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  2 B- 2 B vertical to the central axis L in FIG. 2A;  
     [0017]FIG. 3A illustrates a lateral view of a light source with a function of condensing light according to the preferred embodiment 2 of the invention;  
     [0018]FIG. 3B illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  3 B- 3 B vertical to the central axis L in FIG. 3A; 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0019] The invention especially provides a light source with a function of condensing light, and the light source includes a radiating area, a penetrable layer, and a condensing layer, wherein the penetrable layer consists of a first inner tube and a first outer tube. Any cross section, vertical to the central axis, of the first inner and outer tubes has the same first cross-section curvature. The condensing layer couples to the penetrable layer and together they cover the radiating area inside the light source. The cross-section curvature of any cross section, vertical to the central axis, of the second inner tube of the condensing layer is the same as the first cross-section curvature. The cross section, vertical to the central axis, of the second outer tube of the condensing layer has at least a second cross-section curvature, and the second cross-section curvature is greater than the first one. In this manner, light can be condensed outside the condensing layer, and the luminance of the whole image can be improved by increasing the illumination on the scanned pixel. In addition, the time of exposure for a sensitized component can be shortened, and thus, the scanning time can also be shortened.  
     [0020] The practical applications of the invention are illustrated in the following two embodiments and the attached figures.  
     [0021] Embodiment One  
     [0022] Referring to FIG. 2A, it illustrates a lateral view of a light source with a function of condensing light according to the preferred embodiment 1 of the invention. In FIG. 2A, a light source  202  includes a radiating area  201 , and a penetrable layer  209  coupled with a condensing layer  211 . The penetrable layer  209  and the condensing layer  211  together cover the radiating area  201  in the light source  202 , wherein the radiating area  201  is used for supplying light. The penetrable layer  209  has a first inner tube  208   a  and a first outer tube  210   a;  and the condensing layer is provided with a second inner tube  208   b  and a second outer tube  210   b.  The first inner tube  208   a  couples with the second inner tube  208   b  to be the inner tube of the light source  202 ; and the first outer tube  210   a  couples with the second outer tube  210   b  to be the outer tube of the light source  202 . When the central axis L of the light source  202  is set as the base, the first inner tube  208   a  and the second inner tube  208   b  have the same inner diameter a. The first outer tube  210   a  has a first outer diameter b, and the second outer tube  210   b  has a second outer diameter c, where c&gt;b&gt;a. The second outer diameter c is the maximum distance between the second outer tube  210   b  and the central axis L, and the distance between any point on the second outer tube  210   b  and the central axis L is greater than the value of b.  
     [0023] Furthermore, the inner diameter a, the first outer diameter b, and the second outer diameter c in the light source  202  are fixed values, which enables the light source  202  to be a tube with even thickness. Also, the thickness distribution of the tube of the light source  202  is different from the average thickness of the tube in the light source  102 .  
     [0024] Referring to FIG. 2B, it illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  2 B- 2 B vertical to the central axis L in FIG. 2A. In FIG. 2B, the central axis L of the light source  202  is normally parallel to the surface of the paper  104 , i.e. the central axis L is parallel to the scan line on the paper  104 . The cross section of the first inner tube  208   a  and the cross section of the second inner tube  208   b  are two concentric circles having the central axis L as the same axle center, and the cross section of the first outer tube  210   a  is an arc having the central axis L as the axle center. Namely, the cross sections of the first inner tube  208   a,  the second inner tube  208   b,  and the first outer tube  210   a  have the same first cross-section curvature.  
     [0025] It is noted that the second outer tube  210   b  of the condensing layer  211  of this invention has a second cross-section curvature. The second cross-section curvature is greater than the first cross-section curvature of the second inner tube  208   b,  which enables the light beams to be collected and condensed on the paper  104  after penetrating the condensing layer  211 , and the condensing function can improve the luminance on the paper  104 .  
     [0026] It is also noted that the light source  202  is a tube with even thickness, so that any cross section, vertical to the central axis L, of the first inner tube  208   a,  the second inner tube  208   b,  and the first outer tube  210   a  has the same curvature with the first cross-section curvature. Also, any cross section, vertical to the central axis L, of the second outer tube  210   b  has a second cross-section curvature, and the second cross-section curvature is greater than the first cross-section curvature.  
     [0027] Taking the whole illumination of the light source  202  as  1 , the beams of light provided by the radiating area  201  penetrate the penetrable layer  209  and the condensing layer  211  in the way of 360-degree divergent dispersion and emit outside. Furthermore, the scanned pixel  106 , which is on the paper  104  illuminated by the light source  202 , is taken as an example. Since the second cross-section curvature of the second outer tube  210   b  is greater than the first cross-section curvature of the second inner tube  208   b  of the condensing layer  211 , the light beams start to condense after penetrating the penetrable layer  211 . Then the angle of the beams illuminating on the scanned pixel  106  is enlarged to become A, where the value of ω is greater than the value of Θ in the FIG. 1B. Therefore, the effective surface measure of the inner tube penetrated by illuminating beams on the scanned pixel  106  is increased to (ω/2 n) of the surface measure of the whole inner tube; and the illumination on the scanned pixel  106  is also increased to l*(ω/2 n). Also, the value of l*(ω/2 n) is greater than the value of l*(Θ/2 n) illuminated on the scanned pixel  106  in FIG. 1B. Thus, by changing the curvature of the outer tube of a light source, the light beams emitting from the light source can achieve the function of condensing or dispersing.  
     [0028] Therefore, the design of the condensing layer  211  of the light source  202  in this invention can increase the illumination of the scanned pixel  106 , i.e. the luminance on the scanned pixel  106 . Then, the luminance of the whole scanned image can then be raised, and so can the quality of the scanning. Additionally, the time of exposure for a sensitized component can be shortened, and the scanning time can be shortened as well.  
     [0029] Embodiment Two  
     [0030] Referring to FIG. 3A, it illustrates a lateral view of a light source with a function of condensing light according to the preferred embodiment 2 of the invention. In FIG. 3A, a light source  302  includes a radiating area  301 , and a penetrable layer  309  coupled with a condensing layer  311 . The penetrable layer  309  and the condensing layer  311  together cover the radiating area  301  in the light source  302 , wherein the radiating area  301  is for supplying light. The penetrable layer  309  has a first inner tube  308   a  and a first outer tube  310   a;  and the condensing layer  311  is provided with a second inner tube  308   b  and a second outer tube  310   b.  The first inner tube  308   a  couples with the second inner tube  308   b  to be the inner tube of the light source  302 ; and the first outer tube  310   a  couples with the second outer tube  310   b  to be the outer tube of the light source  302 .  
     [0031] When the central axis L of the light source  302  is set as the base, the first inner tube  308   a  and the second inner tube  308   b  have the same inner diameter a. The first outer tube  310   a  has a first outer diameter b; both ends of the second outer tube  210   b  of the light source  302  have a second outer diameter c; and the center of the second outer tube of the light source  302  has another second outer diameter d, where c&gt;d&gt;b&gt;a.  
     [0032] The second outer diameter d is the maximum distance between the center of the second outer tube  310   b  of the light source  302  and the central axis L, and the second outer diameter c is the maximum distance between two sides of the second outer tube  310   b  of the light source  302  and the central axis L. The distance between any point on the second outer tube  310   b  and the central axis L is greater than the value of b, and the values of the second outer diameters of the second outer tube increase gradually from the center to the ends of the light source  302  This enables the light source  302  to become a tube in which the middle part is slimmer than two ends, which is much different from the light source  102  of the same size.  
     [0033] Since the lateral view of the two ends of the light source  302  is the same as that of the light source in FIG. 2B, it will not be repeated here.  
     [0034] Referring to FIG. 3B, it illustrates a cross-sectional view of a paper illuminated by a light source along the dashed line  3 B- 3 B vertical to the central axis L in FIG. 3A. In FIG. 3B, the central axis L of the light source  302  is normally parallel to the surface of a paper  104 , i.e. the central axis L is parallel to the scan line on the paper  104 . The cross section of the first inner tube  308   a  and the cross section of the second inner tube  308   b  are two concentric circles having the central axis L as the same axle center, and the cross section of the first outer tube  310   a  is an arc by using the central axis L as the axle center. Namely, the cross sections of the first inner tube  308   a,  the second inner tube  308   b,  and the first outer tube  310   a  have the same first cross-section curvature.  
     [0035] It is noted that the second outer tube  310   b  of the condensing layer  311  of this invention has a second cross-section curvature. The second cross-section curvature is greater than the first cross-section curvature, and thus enabling the light beams to be collected and condensed on the paper  104  after penetrating the condensing layer  311 . Namely, the condensing function of the condensing layer  311  improves the luminance on the paper  104 . Besides, the second cross-section curvature of the second outer tube  310   b  of the condensing layer  311  on the middle of the light source  302  is smaller than the second cross-section curvature of the second outer tube  310   b  of the condensing layer  311  on both ends of the light source  302 . The values of the second cross-section curvatures of the second outer tube  310   b  of the condensing layer  311  increase gradually from the center to the ends of the light source  302 . The greater the cross-section curvature of the second outer tube  310   b  of the condensing layer  311  results in the better condensing effect. Therefore, the condensing effect of the condensing layer  311  on the two ends of the light source  302  is better than that on the middle of the light source  302 . The design of such a light source  302  can solve the problem of decreased light caused by optical path differences, and can equal the luminance of the middle part and the two sides of the image collected by the sensitized component. Then, the quality of the scanning can be improved.  
     [0036] In addition, any cross section, vertical to the central axis L, of the first inner tube  308   a,  the second inner tube  308   b,  and the first outer tube  310   a  has the same curvature with the first cross-section curvature. Any cross section, vertical to the central axis L, of the second outer tube  310   b  has a second cross-section curvature, and the second cross-section curvature is greater than the first cross-section curvature.  
     [0037] Taking the whole illumination of the light source  302  also as l, the light beams provided by the radiating area  301  penetrate the penetrable layer  309  and the condensing layer  311  in the way of 360-degree divergent dispersion and emit outside. The scanned pixel  106 , which is on the paper  104  illuminated by the light source  302 , is taken as an example. Since the second cross-section curvature of the second outer tube  310   b  is greater than the first cross-section curvature of the second inner tube  308   b  of the condensing layer  311 , the light beams start to condense after penetrating the penetrable layer  311 . Then the angle of beams illuminating on the scanned pixel  106  is enlarged to α, where ω&gt;α&gt;Θ. Therefore, the effective surface measure of the inner tube penetrated by illuminating beams on the scanned pixel  106  is increased to (α/2 n) of the surface measure of the whole inner tube; and the illumination on the scanned pixel  106  is also increased to l*(α/2 n), where l*(ω/2 n)&gt;l*(α/2 n)&gt;l*(Θ/2 n).  
     [0038] Therefore, the design of the condensing layer  311  of the light source  302  in this invention can increase the illumination of the scanned pixel  106 , that is the luminance on the scanned pixel  106 . Then, the luminance of the whole scanned image can then be raised, and so can the quality of the scan. Additionally, the time of exposure for a sensitized component can be shortened, and the time of scanning can be shortened also.  
     [0039] In addition, the design, whereby the values of the second cross-section curvatures of the second outer tube  310   b  of the condensing layer  311  increase gradually from the center to the ends of the light source  302 , can solve the problem of decreased light caused by optical path differences, and can achieve equal luminance on the whole light source.  
     [0040] However, it is to be understood that the invention is not limited to the disclosed embodiments. For example, the light source can be a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp, or other tubular light sources.  
     [0041] Disclosed above is a light source with the function of condensing light. The design, whereby the value of the second cross-section curvature of the second outer tube of the condensing layer is greater than the value of the first cross-section curvature of the second inner tube, can achieve a condensing effect. The luminance of the whole scanned image can then be raised, so does the quality of scan. Additionally, the time of exposure for a sensitized component can be shortened, and the scanning time can be shortened as well.  
     [0042] While the invention has been described by way of examples and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.