Abstract:
A laser scanning device for use with an image forming apparatus, including an optical housing, a light source installed in the optical housing to generate a laser beam, a deflection unit to deflect the laser beam emitted from the light source, a focusing lens to focus the laser beam deflected by the deflection unit onto a laser scanning surface, a reflective mirror to change the path of the laser beam and thereby, scan the laser beam onto a position of the laser scanning surface, and a mirror assembly unit to diversify installation angles of the reflective mirror to facilitate an assembly thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Application No. 2006-6198, filed Jan. 20, 2006 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    An aspect of the present invention relates to a laser scanning device, and, more specifically, to a laser scanning device for use in image forming apparatuses including digital copiers, laser printers, fax machines, and the like. 
         [0004]    2. Description of the Related Art 
         [0005]    A laser printer uses a laser scanning device, which deflects a laser beam generated from a light source with a polygonal rotating mirror and uses an optical system as a medium to scan the deflected laser beam onto a photosensitive drum. Such a laser scanning device generally accommodates a light source, a polygonal rotating mirror, a drive motor to rotate the polygonal rotating mirror and a scanning lens, in an optical housing thereof. A scanning beam is scanned onto the photosensitive drum through a glass covering installed at a window formed on the sidewall of the optical housing. 
         [0006]      FIG. 1  is a plan view showing the structure of a conventional laser scanning device, and  FIG. 2  is a cross-sectional view taken along line II-II′ in  FIG. 1 . As shown in  FIGS. 1 and 2 , in the conventional laser scanning device  1 , a laser beam emitted from a light source  2  is changed into a parallel light beam or a converging light beam while passing through a collimating lens  3 . Then, the laser beam, having passed through the collimating lens  3  proceeds, via a slit  4 , through a cylindrical lens  5 , and forms an image on the surface of a polygonal mirror  7  linearly in the horizontal direction. Being converged by a focusing lens  11  and incident on the photosensitive drum  9 , the laser beam creates a focal point and forms a desired image on the photosensitive drum  9 . 
         [0007]    The above-described components are typically assembled in a single optical housing  13  to constitute a scanning unit. In addition, a transparent glass covering  15  is attached to the outside of the optical housing  13  to prevent the inflow of foreign substances, such as dust, into the optical housing  13 . 
         [0008]    In addition, an optical sensor  17  provides for horizontal synchronization (sync) with a light L. The optical sensor  17  has a sync signal detection reflector  19  to reflect light having passed through the focusing lens  11  toward the optical sensor  17 . 
         [0009]    In the conventional laser scanning device  1 , the focusing lens  11  and the photosensitive drum  9  are aligned. Thus, the laser beam, having passed through the focusing lens  11 , is focused onto the photosensitive drum  9  without changing an optical path thereof. 
         [0010]      FIG. 3  illustrates the constitution of another conventional laser scanning device. Here, like reference numerals used in  FIGS. 1 and 2  refer to like elements, and detailed description about them will be omitted. As shown in  FIG. 3 , the laser scanning device includes a reflective mirror  21 , which reflects a laser beam, having passed through a focusing lens  11 , upwardly relative to an optical housing  13  so as to form a latent image on the surface of a photosensitive drum  9 ′. Here, the photosensitive drum  9 ′ is installed proximate to an upper portion of the optical housing  13 . A glass covering  15 ′ is provided to the upper portion of the optical housing  13 . 
         [0011]    As described above, changing a path of light, having passed through the focusing lens  11 , is necessary according to the installed positions of the photosensitive drums  9  and  9 ′. To this end, the reflective mirror  21  having diverse installation angles is employed, and the installation positions of glass coverings  15  and  15 ′ are changed accordingly. 
         [0012]    Thus, since the installation positions of the reflective mirror  21  and glass coverings  15  and  15 ′ depend on the laser scanning direction, the optical housing  13  has to be manufactured separately from the reflective mirror  21  and the glass coverings  15  and  15 ′. 
       SUMMARY OF THE INVENTION 
       [0013]    It is, therefore, an aspect of the present invention to provide a laser scanning device capable of supporting diverse laser scanning angles, while using a single optical housing. 
         [0014]    To achieve the above and/or other aspects and advantages, there is provided a laser scanning device for use with an image forming apparatus, comprising an optical housing, a light source installed in the optical housing to generate a laser beam, a deflection unit to deflect the laser beam emitted from the light source, a focusing lens to focus the laser beam deflected by the deflection unit onto a laser scanning surface, a reflective mirror to change the path of the laser beam and thereby, scan the laser beam onto a position of the laser scanning surface, and a mirror assembly unit to diversify installation angles of the reflective mirror to facilitate an assembly thereof. 
         [0015]    According other aspects of the invention, the mirror assembly unit comprises a plurality of mirror supporting members provided to the optical housing to support the installation angles of the reflective mirror according to the position of the laser scanning surface. Also, the mirror support members are paired to support upper and lower sides of the reflective mirror. In addition, the mirror support members have insertion grooves into which the upper and lower sides of the reflective mirror are inserted. The optical housing is provided with a plurality of light outlets. The optical housing further includes glass covering supporting units to support glass coverings, which cover the light outlets. The mirror supporting members support the angle of the reflective mirror that reflects light passed through the focusing lens towards an upper side or a lower side of the optical housing. 
         [0016]    According to other aspects of the present invention, a plurality of reflective mirrors and a plurality of light outlets are formed in a single optical housing. Thus, one optical housing may be effectively shared in correspondence to diverse laser scanning directions. 
         [0017]    As aforementioned, since one optical housing is shared in correspondence to diverse laser scanning directions, a separate optical housing for each laser scanning direction is not required. In consequence, manufacturing costs may be saved, and losses in development investment and development schedules may be minimized. 
         [0018]    Additional and/or other aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0020]      FIG. 1  is a plan view showing the structure of a conventional laser scanning device; 
           [0021]      FIG. 2  is a cross-sectional view taken along line II-II′ in  FIG. 1 ; 
           [0022]      FIG. 3  is a diagram showing the structure of another conventional laser scanning device; 
           [0023]      FIG. 4  is a plan view showing the structure of a laser scanning device according to one embodiment of the present invention; 
           [0024]      FIG. 5  is a cross-sectional view taken along line V-V′ in  FIG. 4 ; 
           [0025]      FIG. 6  is a diagram showing a structure in which laser scanning occurs above the optical housing according to an embodiment of the invention; 
           [0026]      FIG. 7  is a diagram showing a structure in which laser scanning occurs below an optical housing according to an embodiment of the invention; 
           [0027]      FIG. 8  is a cross-sectional view taken along line V-V′ in  FIG. 4 ; 
           [0028]      FIG. 9  is a diagram showing a structure in which laser scanning occurs above the optical housing according to an embodiment of the invention; and 
           [0029]      FIG. 10  is a diagram showing a structure in which laser scanning occurs below an optical housing according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0030]    Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
         [0031]      FIG. 4  is a plan view showing the structure of a laser scanning device according to one embodiment of the present invention, and  FIG. 5  is a cross-sectional view taken along line V-V′ in  FIG. 4 . As shown in  FIG. 4 , the laser scanning device  100  includes a light source  110 , a collimating lens  111 , slits  112 , a cylindrical lens  113 , a polygonal mirror  115 , and a focusing lens  117 . The light source  110  generates a laser beam L, and a laser diode is usually used therefore, although it is understand that other light emitting devices could be employed. The collimating lens  111  changes the laser beam L, emitted from the light source  110 , into a parallel light beam or a converging light beam. The slits  112  restrict the procession of the laser beam L. The cylindrical lens  113  focuses the laser beam L, having passed through the slits  112 , onto the surface of the polygonal mirror  115  linearly in the horizontal direction. The polygonal mirror  115  scans the laser beam L, passed through the slits  112 , by moving the laser beam L at a constant linear velocity in the horizontal direction. To this end, a motor  116  rotates the polygon mirror  115  at a constant velocity. The focusing lens  117 , as an F-θ lens, has a predetermined index of refraction with respect to an optical axis thereof. The focusing lens  117  polarizes the reflected laser beam of a constant speed from the polygon mirror  115  into the main scanning direction (arrow A), corrects aberration, and focuses the laser beam on the laser scanning surface of the photosensitive drum  119 . 
         [0032]    In addition, an optical sensor  121  provides horizontal sync with the laser beam L. The optical sensor  121  includes a sync signal detection reflector  123  to reflect the light, having passed through the focusing lens  117 , towards the optical sensor  121 . 
         [0033]    The above-described components are typically assembled in a single optical housing  125  of the laser scanning device  100 . The optical housing  125  is also provided with a mirror assembly unit where reflective mirrors (a first reflective mirror  126   a  and a second reflective mirror  126   b : see  FIGS. 6 and 7 ) to change the path of the light, having passed through the focusing lens  115 , are assembled. 
         [0034]    Referring to  FIG. 5 , the mirror assembly unit  130  includes first and second mirror supporting members  131  and  133  to support installation angles of the first and second reflective mirrors  126   a  and  126   b , respectively. According to an embodiment of the invention, the first and second mirror supporting members  131  and  133  each comprise pairs of supporters  131   a ,  131   b , and  133   a ,  133   b , respectively, to support both upper and lower sides of the reflective mirrors  126   a  and  126   b , respectively. According other embodiments of the invention (not shown), the first and second mirror supporting member are single structures or comprise more than two structures. 
         [0035]    The first and second pairs of supporters  131   a  and  131   b  and  133   a  and  133   b  each may comprise insertion grooves  131   a ′,  131   b ′, and  133   a ′,  131   a ′, respectively, into which the upper and lower sides of the first and second reflective mirrors  126   a  and  126   b  are inserted, respectively. 
         [0036]    The optical housing  125  is provided with a plurality of light outlets  125   a ,  125   b  and  125   c . Meanwhile, glass covering supporting units  125   d ,  125   e , and  125   f  are formed in the vicinity of the light exits  125   a ,  125   b , and  125   c . The first, second, and third glass coverings  151 ,  153 , and  155  are installed through the glass covering supporting units  125   d ,  125   e , and  125   f , respectively, and prevent the influx of foreign substances from an exterior of the optical housing  125 . 
         [0037]      FIG. 5  illustrates a case in which the photosensitive drum  119  is installed in line with the focusing lens  117 . Thus, light L 1 , having passed through the focusing lens  117 , is transmitted through the first glass covering  151  without changing a path thereof and is then focused on the photosensitive drum  119 . In this case, a separate reflective mirror is not required. 
         [0038]      FIG. 6  is a diagram showing an embodiment of the invention in which laser scanning occurs above the optical housing. As shown in  FIG. 6 , a photosensitive drum  119 ′ is installed above an upper portion of the optical housing  125 . A first reflective mirror  126   a  is installed at the first pair of supporters  131   a  and  131   b  to reflect light L 2 , having passed through the focusing lens  117 , in the upward direction relative to the optical housing  125 . The reflected light L 2  passes through the second glass covering  153  and, collides in focus with the photosensitive drum  119 ′. 
         [0039]      FIG. 7  is a diagram showing an embodiment of the invention in which laser scanning occurs below the optical housing. As shown in  FIG. 7 , a photosensitive drum  119 ″ is installed below a lower portion of the optical housing  125 . A second reflective mirror  126   b  is installed at the second pair of supporters  133   a  and  133   b  to reflect light L 3 , having passed through the focusing lens  117 , in the downward direction relative to the optical housing  125 . The reflected light L 3  from the second reflective mirror  126   b  passes through the third glass covering  153  and, then, collides in focus with the photosensitive drum  119 ″. 
         [0040]    According to another aspect of the invention shown in  FIGS. 8 through 10 , a reflective mirror  126   d  is hingedly attached to the optical housing  125  using hinge  135  to allow a single mirror  126   d  to provide multiple reflection directions. The optical housing  125  is provided with a plurality of light outlets  125   a ,  125   b  and  125   c . Glass covering supporting units  125   d ,  125   e , and  125   f  are formed in the vicinity of the light exits  125   a ,  125   b , and  125   c . The first, second, and third glass coverings  151 ,  153 , and  155  are installed through the glass covering supporting units  125   d ,  125   e , and  125   f , respectively, and prevent the influx of foreign substances from an exterior of the optical housing  125 . However, it is understood that other constructions are possible to provide a single reflecting mirror and a single mirror supporting member that is able to shift positions and attitudes at which the light is not reflected, reflected upward, or reflected downward. Additionally, while not required, it is understood that mirror supporting members can further be included to secure the mirror  126   d  in its angled positions. 
         [0041]    As shown in  FIG. 8 , the photosensitive drum  119  is installed in line with the focusing lens  117 . As such, the mirror  126   d  is rotated about the hinge  135  to not be in the light path between the light source  115  and the photosensitive drum  119 . Thus, light L 1 , having passed through the focusing lens  117 , is transmitted through the first glass covering  151  without the mirror  126   d  changing a path thereof, and is then focused on the photosensitive drum  119 . 
         [0042]    As shown in  FIG. 9 , a photosensitive drum  119 ′ is installed above an upper portion of the optical housing  125 . The reflective mirror  126   d  is rotated about the hinge to reflect the light L 2 , having passed through the focusing lens  117 , in the upward direction relative to the optical housing  125 . The reflected light L 2  passes through the second glass covering  153 , and collides in focus with the photosensitive drum  119 ′. 
         [0043]    As shown in  FIG. 10 , a photosensitive drum  119 ″ is installed below a lower portion of the optical housing  125 . The reflective mirror  126   d  is rotated about the hinge to reflect the light L 3 , having passed through the focusing lens  117 , in the downward direction relative to the optical housing  125 . The reflected light L 3  from the second reflective mirror  126   b  passes through the third glass covering  153  and collides in focus with the photosensitive drum  119 ″. 
         [0044]    Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.