Abstract:
The invention provides an image forming apparatus that includes a light source receiving printing data to generate a scanning beam; a polygon mirror receiving the scanning beam to scan in a predetermined width; a reflection mirror reflecting the scanned beam; a blocking member moving between a blocking position blocking the scanning beam and an non-blocking position allowing the scanning beam to pass; a developing cartridge provided to move inside/outside of the image forming apparatus to move the blocking member, and accommodating a photosensitive body receiving the scanning beam reflected by the reflection mirror; a sensor interposed between the polygon mirror and the reflection mirror to detect a first position of the scanned beam; and a controller determining whether the developing cartridge is mounted on the basis of the detected signal of the sensor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Korean Patent Application No. 2005-92287, filed on Sep. 30, 2005, 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]     Aspects of the present invention relate to an image forming apparatus and more particularly, to an electrophotographic image forming apparatus comprising a blocking member blocking or passing a scanning beam.  
         [0004]     2. Description of the Related Art  
         [0005]     An image forming apparatus generates a scanning beam, such as a laser, based on printing data, and enables toner to be developed according to a surface voltage distribution of a photosensitive body that receives the scanning beam.  
         [0006]     Because of potential health and safety issues, the scanning beam should be prevented from escaping outside the image forming apparatus, and exposure of users to the scanning beam should be prevented.  
         [0007]     In response to such a requirement, Japanese Patent First Publication Nos. 5-19603, 6-297755, and 6-305185 have been disclosed.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an aspect of the invention to provide an image forming apparatus in which outside exposure to a scanning beam is prevented.  
         [0009]     Additional aspects and/or 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.  
         [0010]     The foregoing and/or other aspects of the present invention can be achieved by providing an image forming apparatus comprising: a light source that receives printing data to generate a scanning beam; a polygon mirror that receives the scanning beam and that scans the scanning beam in a predetermined width; a reflection mirror that reflects the scanned beam; a blocking member that moves between a blocking position blocking the scanning beam and a non-blocking position allowing the scanning beam to pass; a developing cartridge comprising a photosensitive body that receives the scanning beam reflected by the reflection mirror, wherein the developing cartridge is removably mounted in the image forming apparatus and wherein the developing cartridge interacts with the blocking member to move the blocking member when the developing cartridge is installed in or removed from the image forming apparatus; a sensor interposed between the polygon mirror and the reflection mirror to detect the scanning beam when the scanning beam is not blocked by the blocking member; and a controller that determines whether the developing cartridge is mounted in the image forming apparatus on the basis of whether the scanning beam is detected by the sensor.  
         [0011]     According to an aspect of the present invention, the blocking member is interposed between the light source and the polygon mirror such that when the blocking member is in the blocking position, the blocking member blocks the scanning beam of the light source.  
         [0012]     According to an aspect of the present invention, the blocking member is interposed between the polygon mirror and the reflection mirror such that when the blocking member is in the blocking position, the beam scanned by the polygon mirror is blocked between the polygon mirror and the reflection mirror.  
         [0013]     According to an aspect of the present invention, the image forming apparatus further comprises a casing that accommodates the light source, the polygon mirror and the reflection mirror, and wherein the blocking member is movably supported on the casing.  
         [0014]     According to an aspect of the present invention, the controller controls an on or off operation of the light source on the basis of whether the developing cartridge is mounted in the image forming apparatus.  
         [0015]     The foregoing and/or another aspects of the present invention can be achieved by providing a image forming apparatus comprising: a light source that receives printing data to generate a scanning beam; a polygon mirror that receives the scanning beam and that scans the scanning beam in a predetermined width; a reflection mirror that reflects the scanned beam; a blocking member that moves between a blocking position blocking the scanning beam and a non-blocking position allowing the scanning beam to pass; a housing that includes a cover hingedly coupled to the housing, wherein the cover rotatably opens and closes; a sensor interposed between the polygon mirror and the reflection mirror to detect the scanning beam when the scanning beam is not blocked by the blocking member; and a controller that determines whether the cover is open or closed on the basis whether the scanning beam is detected by the sensor.  
         [0016]     According to an aspect of the present invention, the controller controls an on and off operation of the light source on the basis of whether the cover is open or closed.  
         [0017]     According to an aspect of the present invention, the image forming apparatus further comprises a developing cartridge accommodating a photosensitive body receiving the scanning beam reflected by the reflection mirror, and removably mounted in the image forming apparatus when the cover is open.  
         [0018]     According to an aspect of the present invention, a guide hole is formed in the casing, and the blocking member further comprises an arm that extends through the guide hole.  
         [0019]     According to an aspect of the present invention, the developing cartridge moves the arm when of the developing cartridge is installed in or removed from the image forming apparatus.  
         [0020]     According to an aspect of the present invention, the casing further comprises a seal to prevent an inflow of alien substances through the guide hole.  
         [0021]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     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:  
         [0023]      FIG. 1  is an exploded perspective view illustrating a laser scanning unit according to an aspect of the present invention,  
         [0024]      FIGS. 2A and 2B  are sectional views illustrating an installing process of an image forming apparatus according to a first embodiment of the present invention,  
         [0025]      FIGS. 3A and 3B  are sectional views illustrating an installing process of an image forming apparatus according to a second embodiment of the present invention,  
         [0026]      FIG. 4  is a block diagram illustrating a control operation of the image forming apparatus according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0027]     Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. When the same elements are present in more than one embodiment, they will typically be described in the first embodiment and the description may be omitted in the discussion of the other embodiments. The embodiments are described below so as to explain the present invention by referring to the figures.  
         [0028]      FIG. 1  is an exploded perspective view illustrating a laser scanning unit  100 . A light source  110  receives printing data and generates and scans a laser scanning beam corresponding to the printing data. The scanning beam is directed to a polygon mirror  140  through a collimating lens  120  and a cylinder lens  130 . The polygon mirror  140  reflects the scanning beam while rotating at a high speed to scan the beam in a predetermined width. The scanned beam passes through an fθ lens  150  and then is reflected by a reflection mirror  160  to be scanned on an external photosensitive body  10 . A surface of the photosensitive body  10  scanned by the scanning beam is supplied with a predetermined voltage to form an electrostatic latent image.  
         [0029]     In the laser scanning unit  100  with such a configuration, a blocking member (see  190  in  FIG. 2A ) can block the scanning beam by being positioned in one of the locations A through F of  FIG. 1 , as will be described below.  
         [0030]     Particularly, if the blocking member  190  is positioned in one of the locations A, B and C of  FIG. 1 , the scanning beam between the light source  110  and the polygon mirror  140  is made of a singular beam. Thus, the blocking member  190  can be advantageously formed small in size.  
         [0031]     If the blocking member is positioned on one of the locations D, E or F in  FIG. 1 , the blocking member cannot be as small as it can be in the locations A, B or C in  FIG. 1 , since the scanning beam has a width created by being scanned by the polygon mirror  140 . However, a relatively small blocking area can be provided in comparison with the width of the scanning beam reflected to the photosensitive body  10  by the reflection mirror  160 .  
         [0032]     Reference numeral  170  in  FIG. 1  denotes a sensor that detects a first position of the scanning beam scanned by the polygon mirror  140 , and reference numeral  180  denotes a position detecting reflection mirror to reflect the beam onto the sensor  170  when the scanned beam is positioned at the final position. According to aspects of the present invention, the sensor  170  may be positioned in any location from which it detects the scanning beam when the scanning beam is not blocked by the blocking member  190  and does not detect the scanning beam when the scanning beam is blocked by the blocking member.  
         [0033]      FIGS. 2A and 2B  are side views illustrating an interrelation between the laser scanning unit  100  and a developing cartridge  200 , when the blocking member  190  is positioned at the A, B or C locations in  FIG. 1 .  
         [0034]     The laser scanning unit  100  is fixed in the inside of the housing  2  of the image forming apparatus  1 , and the developing cartridge  200  is detachably mounted to the image forming apparatus  1 . Accordingly, the laser scanning unit  100  and the developing cartridge  200  can interact when the developing cartridge  200  is installed into and detached from the image forming apparatus  1 .  
         [0035]     More particularly, the laser scanning unit  100  comprises the blocking member  190  interposed between the light source  110  and the polygon mirror  140 .  
         [0036]     The blocking member  190  may be hingedly coupled to a casing  101  to move between a blocking position (see position “a” in  FIG. 2A ) blocking the scanning beam generated from the light source  110  and a non-blocking position (see position “b” in  FIG. 2B ) that allows the scanning beam to pass without being blocked. The blocking member  190  is not limited to this exact configuration. For example, the casing  101  and the blocking member  190  may be slidably coupled to move the blocking member  190 , or the blocking member  190  may be integrally formed with the casing  101  to move through elastic deformation.  
         [0037]     The blocking member  190  is positioned on the first blocking position “a” to move to the non-blocking position “b” when a developing cartridge  200  is mounted in the image forming apparatus  1  and then to be restored to the blocking position “a” when the developing cartridge  200  is removed from the image forming apparatus  1 . An elastic member such as a spring can be used to bias the blocking member  190  so that the blocking member  190  is restored to the blocking position “a” when the developing cartridge  200  is removed.  
         [0038]     The blocking member  190  comprises an arm  191  that extends through a guide hole  102  provided in the casing  101 . The arm  191  interacts with the developing cartridge  200  to move the blocking member  190  into the non-blocking position “b” when the developing cartridge  200  is mounted in the image forming apparatus  1 , so that the blocking member  190  does not block the scanning beam generated from the light source  110 . Then, when the developing cartridge  200  is removed from the image forming apparatus  1 , the arm  191  no longer interacts with the developing cartridge  200  and the blocking member moves to the blocking position “a”.  
         [0039]      FIG. 2A  illustrates a state in which the developing cartridge  200  is being installed into, but is not yet mounted in the image forming apparatus  1 , and  FIG. 2B  illustrates the state in which the developing cartridge  200  has been mounted in the image forming apparatus  1 .  
         [0040]     In the developing cartridge  200 , a projection  201  is formed to move the arm  191  of the blocking member  190 . The projection  201  can be provided as a part of the developing cartridge  200  without deforming the outside shape of the developing cartridge  200 , or with deforming an outside part thereof. Alternatively, an extra member can be provided attached to the developing cartridge  200 .  
         [0041]     As shown in  FIGS. 2A and 2B , before the developing cartridge  200  is mounted to the image forming apparatus  1 , the blocking member  190  is positioned in the blocking position “a”. After the developing cartridge  200  is mounted, the blocking member  190  is positioned in the non-blocking position “b” due to the moving of the arm  191  caused by interaction with the projection  201 .  
         [0042]      FIGS. 3A and 3B  are side views illustrating an interrelation between the laser scanning unit  100  and the cover  3  when the blocking member  190  is positioned at locations A, B, or C in  FIG. 1 . Since the configuration of the laser scanning unit  100  is substantially the same as that in  FIGS. 2A and 2B , the description thereof will be omitted.  
         [0043]     The cover  3  is provided to be hingedly coupled to the housing  2  and to rotatably open and close. The cover  3  is opened when the developing cartridge  200  is installed in or removed from the image forming apparatus land is closed when the developing cartridge has been mounted to the image forming apparatus  1 . The cover  3  is kept closed during normal operation of the image forming apparatus.  
         [0044]     A rib  4  is projectedly formed in the cover  3  to move the blocking member  190 . Accordingly, when the cover  3  is rotated to a closed position, the rib  4  contacts the arm  191  of the blocking member  190 , thereby moving the arm  191  so that the blocking member  190  is moved to the non-blocking position “b”. An elastic member such as a spring can be used to bias the blocking member  190  so that the blocking member  190  is restored to the blocking position “a” when the cover is opened.  
         [0045]     The rib  4  is projectedly formed in the cover  3  to rotate with respect to the casing  101  of the laser scanning unit  100 . To this end, the shape of the casing  101  can be suitably provided or modified. Alternatively, the rib  4  may be provided transversely at a side edge of the cover  3 , and an extension may be formed at a lower part of the arm  191  of the blocking member  190  to move in contact with the rib  4 .  
         [0046]     In the embodiments of the present invention described above, the blocking member  190  is positioned between the light source  110  and the polygon mirror  140 . However, the blocking member  190  can also be positioned so in locations D, E or F in  FIG. 1 , so that the blocking member  190  can be moved to block the scanning beam in these positions. In such a case, the blocking area of the blocking member  190  must be larger in comparison with the above embodiment of the present invention. However, even in such a case, the blocking area still has a smaller area than would be required to block the scanning beam after the scanning beam passes through the reflection mirror  160  and before the scanning beam exits to the outside of the laser scanning unit  100 .  
         [0047]     In the above embodiments, a seal can be provided to the guide hole  102  formed on the casing  101  of the laser scanning unit  100  to block the inflow of alien substances from the outside, such as dust or airborne toner particles. Such a seal can be made of a flexible material such as sponge or rubber, or may be in the form of a film or tape so that the smooth movement of the blocking member  190  is not prevented.  
         [0048]      FIG. 4  is a block diagram illustrating a control operation of the laser scanning unit  100  having the blocking member  190 .  
         [0049]     In the image forming apparatus  1 , a controller  20  controlling each component is provided, and a display  30  controlled by the controller  20  is provided to display the state of the image forming apparatus  1 . The controller  20  controls an on and off operation of the light source  110  of the laser scanning unit  100  based on the signal detected from the sensor  170  provided in the image forming apparatus  100  in  FIG. 1 .  
         [0050]     For example, in the image forming apparatus  1  having the laser scanning unit  100  and the developing cartridge  200  as shown in  FIGS. 2A and 2B , the first position of the scanning beam of the light source  110  can be detected through the sensor  170  in  FIG. 1  only when the developing cartridge  200  is mounted, (that is, the state of  2 B in  FIG. 1 ). As a result, the controller  20  can determine whether or not the developing cartridge  200  is mounted to the image forming apparatus through a detecting signal of the sensor  170 . That is, if the developing cartridge  200  is not mounted to the image forming apparatus  1 , the blocking member  190  is positioned in the blocking position “a” as shown in  FIG. 2A , and the scanning beam does not reach the sensor  170 . On the other hand, if the developing cartridge  200  is mounted to the image forming apparatus  1 , the blocking member  190  is positioned in the non-blocking position “b” as shown in  FIG. 2B , and the scanning beam reaches the sensor  170 .  
         [0051]     Accordingly, the controller  20  can inform a user through the display  30  when the developing cartridge  200  is not mounted, and further can cut off electric power of the light source  110  so that the scanning beam is not generated.  
         [0052]     Similarly, in the image forming apparatus  1  having the laser scanning unit  100  and the cover  3  as shown in  FIGS. 3A and 3B , the controller  20  can determine the cover  3  whether the cover is opened or closed.  
         [0053]     Accordingly, the controller  20  informs a user through the display  30  if the cover  3  is not closed, and can cut off an electric power of the light source  110  to prevent the scanning beam from being generated.  
         [0054]     As described above, when the blocking member is interposed between the light source and the polygon mirror, or between the polygon mirror and the reflection mirror, the scanning beam is blocked with a relatively small blocking area and with improved blocking efficiency.  
         [0055]     Furthermore, a determination can be made as to whether or not the developing cartridge is mounted or whether or not the cover is closed based on whether or not the scanning beam is detected by the sensor, since the scanning beam is blocked when the developing unit is removed or when the cover is opened. The result of this determination can be used to control the on and off operation of the light source, thereby providing addition protection to users when the developing cartridge is removed or the cover is open. Also the image forming apparatus advantageously need not have an extra sensor to detect whether the developing cartridge is mounted in the image forming apparatus or the cover is open or closed.  
         [0056]     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 this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.