Abstract:
Embodiments of the invention disclose a light-path device of an optical scanner that includes a curved-surface optical element and a light-path module. The arrangement between the curved-surface optical element and the light-path module may be designed such that the length of a light-path route through the light-path device may be adjusted to accommodate various sized objects to be scanned and physics characteristics of the photoelectric conversion device included in the scanner to convert the image into an electrical signal.

Description:
FIELD OF THE INVENTION 
     The invention relates to a light-path device of curved-surface optical element, especially to a light-path device that has a curved-surface optical element and is arranged in an optical scanner for adjusting the total light-path length in the light-path device. 
     BACKGROUND OF THE INVENTION 
     One of the general application principles of an optical scanner is that a light beam is reflected through a light-path device and formed into an image by a lens and, a charge-coupled device is further applied to convert the light signal into digital signal capable of being memorized and processed by a computer. However, since the limitation of a certain light-path&#39;s length is required to form the desired image, the light has to be reflected several times by a plurality of reflection mirrors in the light-path device to effectively reduce its dimension. Therefore, in the light-path device, the number, the size, and the inter-corresponding arrangement and position of the reflection mirrors will decide the light-path route of a light-path device and, in addition, help match with the functions of magnification and reduction of a lens to determine the length of the light-path. 
     Please refer to  FIG. 1 , which is a three-dimensional structural illustration for a flatbed optical scanner typically seen in the current market. An object supporting glass  16  is arranged on the upper side surface of an outer shell  11  of a scanner  1  for placing a reflective object  10 . A light-path device  2  is driven by a driving device  13  for proceeding in a linear motion along the direction of a guiding rod  14  in the hollow outer shell  11 , such that an image scanning job is executed on the reflective object  10  placed on the object supporting glass  16 . 
     Please refer to  FIG. 2 , which is an illustration for the light-path route in a flatbed optical scanner according to the current prior art. The route of the light-path is determined by the light-path device  2 , which is comprised of light source  20 , light-path module  21 , and charge-coupled device  22 . The light-path module  21  includes three reflection mirrors  211 ,  212 ,  213 , and a lens  214 . The light of the light source  20  penetrates through the object supporting glass  16  irradiates upon the reflective object  10 . The light irradiated from the reflective object  10  is then reflected sequentially by the first reflection mirror  211 , the second reflection mirror  212 , and the third reflection mirror  213 , which finally reflects the light to a lens  214 , from which the focused light is further irradiated to a charge-coupled device  22 . 
     To reduce an object plane in the prior art described above in order to fit the image of the reflective object  10  on the charge coupled device  22 , magnification and reduction functions of the lens may be altered. However, because of the limitations associated with the specification and physics of the lens itself during manufacture and the size of the scanned object itself, the length of the light-path route must be designed to be long enough to fit the image of the entire scanned object  10  on the lens. Hence, improvements in the adjustability of the light-path device in order to adjust the length of the light path is needed. 
     SUMMARY OF THE INVENTION 
     In light of the limitations of above prior arts described above, embodiments of the present invention provide an innovative design of light-path device including curved-surface optical element design. One of the main objectives of the invention is to provide a light-path device having a curved-surface, wherein the device is arranged in an optical scanner. Appropriately arranging the inter-relational position of the curved-surfaced light-path device (e.g., a curved-surface optical element) with reflection mirrors or photoelectric conversion devices in the light-path route can allow the length of the light-path route to be adjusted such that different length light-path route will be determined according to the different positions of the curved-surface optical element in the light-path route. Thus, a document is scanned at an appropriate position that is pre-designed without the limitations of the size of the scanned document or the photoelectric conversion device itself. 
     The invention includes a curved-surface optical element, a light source, a light-path module, a light-focusing device, and a photoelectric conversion device. The light-path module includes a reflection device and a light-focusing device, wherein the reflection device is comprised of a plurality of reflection mirrors, and the light-focusing device may be a lens. The light source provides the light needed in a scanning procedure, and the reflection mirrors sequentially reflect the light penetrating through the transparent supporting glass and reflected from the object to reach a predetermined length of a reflective light path, while the lens may receive the reflective light reflected from the reflection mirrors and focus it into an image. The photoelectric conversion device then receives the light focused as an image by the lens and converts it into an electric signal. 
     The relation between the system&#39;s magnification ratio and the subsystem&#39;s magnification ratio is applied such that, in the light-path design of the curved-surface optical element and the light-path of the light-path module, the positions between the curved-surface optical element and the light-path module may determine the value of the system magnification, and hence also determine the needed total length of the light-path route. 
     In a preferable embodiment, a convex optical element is designed between the object and the light-path module for adjusting the light-path length. 
     In another preferable embodiment, a concave optical element is designed between the object and the light-path module for adjusting the light-path length. 
     In a further preferable embodiment, a concave optical element or a convex optical element is designed between the light-path module and the photoelectric conversion device for adjusting the light-path length. 
     In a further another preferable embodiment, a concave optical element and a convex optical element are respectively designed between the object and the light-path module, and between the light-path module and the photoelectric conversion device for adjusting the light-path lengths. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a three-dimensional structural illustration for a flatbed optical scanner according to the current prior arts. 
         FIG. 2  is an illustration for a light-path route in a flatbed optical scanner according to the current prior arts. 
         FIG. 3  is a first preferable embodiment according to the invention. 
         FIG. 4  is a second preferable embodiment according to the invention. 
         FIG. 5  is a third preferable embodiment according to the invention. 
         FIG. 6  is a fourth preferable embodiment according to the invention. 
         FIG. 7  is a fifth preferable embodiment according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention discloses a light-path device (e.g., a curved-surface optical element) arranged in a light-path module, wherein a light-path route is designed and adjusted through the variation of different light-path positions for the curved-surface optical element to focus or disperse the optical image. This ability to design and adjust the light path results in being able to keep the original reflection function of the light-path route, while also providing an innovative technique for changing the length of the entire light-path route to flexibly scan various shaped objects and maintaining the quality of the scanned image. 
     The principle of the invention is to apply the design of an image magnification ratio (M) in the light-path. The magnification ratio of the image reflected and focused by the reflection mirrors and the lens is matched with the position of the curved-surface optical element for adjusting the magnification ratio, such that the reflection, the focus, and the photoelectric conversion of the image may be properly completed. For the magnification ratio of an ordinary document, the size (Wd) of the surface of the document, the size (We) of the sensing cell of the photoelectric conversion device, and the diffraction limitation of the lens design must be considered, all which may be expressed as following formula:
 
Magnification= Q (image size)/ P (object size)= Hi (image height)/ Ho (object height)=( Nc*Wc )/ Wd  
 
     Wherein, Nc is the number applied by the sensing cell of the photoelectric conversion device, so the system magnification ratio (M.sub.system) may be designed by a manner of separation system; namely, a formula may be described as the following:
 
 M .sub.system= M 1 *M 2 *M 3* . . .  Mn  
 
     Wherein, n is the number of the separation system. In other words, the magnification ratio (M.sub.system) of a major system may be designed as the product of the magnification ratios of several separated sub-systems. Thus, aside from the magnification ratio of the lens&#39; object system, the other sub-system&#39;s magnification ratio may be adjusted so that the magnification ratio of the major system, and the design of the entire light-path route is further determined. The curved-surface optical element described in embodiments of the invention may be responsible for the ability of adjusting the magnification ratio of the sub-system to further adjust the magnification ratio of the entire major system. Thus, by arranging different positions of the curved-surface optical elements, the functions of the convergence (reduction) or the dispersion (magnification) of the image may be achieved such that the design of the curved-surface optical element builds in flexibility without the limitation posed by the diffraction extremity of the lens itself. Thus, the magnification ratio can be designed as the following:
 
 M .sub.system= M .sub.lens* M .sub.curved-surface optical element
 
     In this way, the adjustment of the light-path route for the reflection, the focus, and the photoelectric conversion of the image by an entire optical scanner is achieved. For convenient description, in the following embodiment, the reflection device (including plural reflection minors) and the lens are regarded as a sub-system M.sub.lens. If the plural reflection mirrors and the lens are assumed as a light-path module, then, this light-path module may be designed correspondingly with the curved-surface optical element, and the light-path modules for different magnification ratios may then be matched correspondingly with the curved-surface optical elements of different magnification ratios. 
     Please refer to  FIG. 3 , which is a first preferable embodiment according to the invention-curved-surface optical element in the light-path of a scanner, the length of the light-path route in the light-path device of a scanner may be adjusted, wherein the light-path device  3  includes a light-source device (light source  30 ), a light-path module  31 , and a photoelectric conversion device  32  (may be a CCD), where the light-path module  31  further includes a reflection device (comprised of reflection mirrors  311 ,  312 ,  313 ) and a light-focusing device (lens  314 ). The light source  30 , providing a light needed by the scanning procedure, irradiates reflective object  10  through the transparent supporting glass  16 . The reflection mirrors  311 ,  312 ,  313  sequentially reflect the light reflected from the object  10  placed on the transparent supporting glass  16  to reach a predetermined length of a reflective light-path, while the lens  314 , a light-focusing device capable of focusing light into image, receives the light reflected from the reflection mirror  313  and focuses it into an image. The photoelectric conversion device  32  receives the light of the image focused by the lens  314  and converts it into electric signal. 
     One feature of the first embodiment of the present invention is that a curved-surface optical element  33  is designed to be disposed between the light-path module  31  and the object  10 , and/or a curved-surface optical element  34  is designed to be disposed between the light-path module  31  and the photoelectric conversion device  32 . Hence, one or two of the curved-surface optical elements  33 ,  34  may be chosen, such that a scanner design has a desired system magnification ratio defined by M.sub.system=M.sub.lens*M.sub.curved-surface optical element. The light-path module  31  may be designed as a sub-system containing the lens  314 , and the curved-surface optical element  33  and the curved-surface optical element  34  may be designed as another sub-system (only one of the curved-surface optical element  33  or the curved-surface optical element  34  is applied in this instance). These designs may be governed by the following: M.sub.system=M.sub.light-path module*M.sub.curved-surface optical element  33  or M.sub.system=M.sub.light-path module*M.sub.curved-surface optical element  34 , wherein the M.sub.light-path module is the M.sub.lens described above. In the instance when the curved-surface optical element  33  is regarded as a first sub-system and the curved-surface optical element  34  is regarded a second sub-system (i.e., the curved-surface optical element  33  and the curved-surface optical element  34  are both included in the design, the following formula is may be used in the design: M.sub.system=M.sub.light-path module*M.sub.curved-surface optical element  33 *M.sub.curved-surface optical element  34 , wherein the M.sub.light-path module is the M.sub.lens described above. 
     Please refer to  FIG. 4 , which is the second preferable embodiment according to the invention. As shown in  FIG. 4 , this embodiment specifies a design where the curved-surface optical element  330  is disposed between the object  10  and the light-path module  31 . Here, the light progressing from the object  10  toward the light-path module  31  will be focused (shrunk) into the light-path module  31 . In other words, through the curved-surface optical element  330 , the image may be irradiated into the light-path module  31  within a shorter light-path route, so the length of the light-path will be shorter in comparison to conventional designs where there is no curved-surface optical element  330 . In other words, in a situation where the size of the object  10  is not changed, the curved-surface optical element  330  may adjust the length of the light-path route between the object  10  and the light-path module  31 , wherein the curved-surface optical element  330  is a convex optical element (i.e., its convex surface is toward the object  10 ). 
     Please refer to  FIG. 5 , which is a third preferable embodiment according to the invention. As shown in  FIG. 5 , this embodiment is roughly similar to that shown in  FIG. 4 . However, the curved-surface optical element  331  is a concave optical element (i.e., its concave surface is toward the object  10 ). Therefore, either a convex optical element or a concave optical element may be used as curved-surface optical element  330 ,  331  in this embodiment of the invention. By changing the position of the curved-surface optical element in the light-path route-the light-path length between the object  10  and the light-path module  31  may be changed. Of course, the position in either case of the curved-surface optical element  330  in  FIG. 4  or the curved-surface optical element  331  in  FIG. 5  may be designed according to the light-path length of actual need. The light-path route summarized from  FIG. 3  through  FIG. 5  is described sequentially as the following: light-source device (light source  30 )=&gt;object  10 =&gt;curved-surface optical element (curved-surface optical element  330  or curved-surface optical element  331 )=&gt;reflection device (reflection mirrors  311 ,  312 ,  313 )=&gt;light-focusing device (lens  314 )=&gt;photoelectric conversion device  32  (CCD). 
     Please refer to  FIG. 6 , which is the fourth preferable embodiment of the invention. As shown in  FIG. 6 , this embodiment specifies a curved-surface optical element  340  be disposed between the light-path module  31  and the photoelectric conversion device  32 . Here, the light progressing from the light-path module  31  toward the photoelectric conversion device  32  will be dispersed (magnified) by the curved-surface optical element  340  on the path to the photoelectric conversion device  32 . Hence, the light-path length will be shortened in comparison with conventional designs where there is no curved-surface optical element  340 . Namely, in situations where the size of the photoelectric conversion device  32  is not changed, the curved-surface optical element  340  may adjust the length of the light-path route from the light-path module  31  to the photoelectric conversion device  32 . In other words, the curved-surface optical element  340  may irradiate the image into the photoelectric conversion device  32  with a shorter light-path length such that the dispersed image will be processed by a photoelectric conversion within the photoelectric conversion device  32 . By changing the position of the curved-surface optical element  340  in the light-path route, the light-path length between the photoelectric conversion device  32  and the light-path module  31  may be changed. The curved-surface optical element  340  may be a convex optical element or a concave optical element. The light-path route summarized from FIG. and  FIG. 6  is described sequentially as the following: light-source device (light source  30 )=&gt;object  10 =&gt;reflection device (reflection mirrors  311 ,  312 ,  313 )=&gt;light-focusing device (lens  314 )=&gt;curved-surface optical element (curved-surface optical element  340 )=&gt;photoelectric conversion device  32  (CCD). 
     Please refer to  FIG. 7 , which is the fifth preferable embodiment of the invention. As shown in  FIG. 7 , a curved-surface optical element  332  is designed to be disposed between the light-path module  31  and the photoelectric conversion device  32 , and another curved-surface optical element  341  is designed to be disposed between the light-path module and the scanned object  10 . In this design, the size between the light-path module  31  and the photoelectric conversion device  32  and the size between the light-path module  31  and the scanned object  10  may be adjusted simultaneously. In operation, the curved-surface optical element  332  may converge the image to make the photo-image of the scanned object  10  prior to irradiating the image through the light-path module  31 , and the curved-surface optical element  341  may disperse the image coming from the light-path module  31  before being processed by a photoelectric conversion in the photoelectric conversion device  32 . By changing the positions of the curved-surface optical elements  332 ,  341  in the light-path route, the entire light-path route may be adjusted to reach a desired magnification ratio. In particular, the length of the entire light-path route may be shortened. Furthermore, the size and volumes of the light-path device and the entire optical scanner may be reduced, resulting in a relative savings in cost while still providing an effective scanning design. The light-path route summarized from  FIG. 3  and  FIG. 7  is described sequentially as the following: light-source device (light source  30 )=&gt;object  10 =&gt;curved-surface optical element (curved-surface optical element  332 )=&gt;reflection device (reflection mirrors  311 ,  312 ,  313 )=&gt;light-focusing device (lens  314 )=&gt;curved-surface optical element (curved-surface optical element  341 )=&gt;photoelectric conversion device  32  (CCD). 
     Applied in embodiments of the invention, the curved-surface optical element positioned in and inter-related with the light-path device appropriately may be adjusted to reach a desired design of a magnification ratio. By arranging the curved-surface optical element between the scanned document and the light-path module, it may magnify the scanned image and further shorten the required distance between the scanned object and the light-path module. Additionally, the curved-surface optical element designed between the light-path module and the photoelectric conversion device may shrink the scanned image and further reduce the required distance between the light-path module and the photoelectric conversion device.