Abstract:
A developing apparatus includes sealing members which are installed on both inside walls of a housing and closely contact the housing, a developer roller, and a blade to prevent the toner contained in the housing from leaking out. Each sealing member includes a first sealing member and a second sealing member. The first sealing member has a side part that elastically and closely contacts one inside wall of the housing and a short side part of the blade, and a front part that elastically and closely contacts the outer circumference of the developer roller. The second sealing member overlaps with the first sealing member and has a front part that elastically and closely contacts an inside surface of the blade and the outer circumference of the developer roller. Therefore, deterioration of a close contact of the sealing members due to compression and deformation of the sealing members may be prevented. Accordingly, a developing apparatus is configured to prevent leakage of toner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Application No. 2002-29952, filed May 29, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a developing apparatus of a dry electrophotographic image forming apparatus, and more particularly, to a developing apparatus having a sealing member to prevent leakage of dry toner (hereinafter referred to as toner) contained in the developing apparatus. 
     2. Description of the Related Art 
     In general, a dry electrophotographic image forming apparatus contains toner and supplies the toner to a photoreceptor medium, such as a photoreceptor drum or the like, to develop a latent electrostatic image on the photoreceptor medium. Here, the toner is minute powder having a predetermined color and has to be contained in the developing apparatus except when being adhered to the latent electrostatic image. Therefore, the developing apparatus of the dry electrophotographic image forming apparatus using toner generally has a sealing member to prevent leakage of the toner. 
     FIG. 1 is an exploded perspective view of a conventional developing apparatus having sealing members. As shown in FIG. 1, the conventional developing apparatus includes a housing  100  which contains toner, and a blade  130  and a developer roller  120  which are respectively combined with the housing  100 . The conventional developing apparatus also includes sealing members  140  which are disposed on insides  102  of right and left walls  104  of the housing  100  and closely contact the blade  130  and the developer roller  120  to prevent the toner in the housing  100  from leaking. 
     The developer roller  120  is coupled to couplings  101  which are prepared in the right and left walls  104  of the housing  100 , to rotate. The developer roller adheres the toner in the housing  100  onto an outer circumference thereof, and supplies the toner to a photoreceptor drum (not shown) to develop a latent electrostatic image on the photoreceptor drum. 
     The blade  130  is conjoined with an upper surface  103  of the housing  100  in order to longitudinally contact the outer circumference of the developer roller  120 . Thus, the blade  130  rubs against the outer circumference of the developer roller  120  that is rotating to scrape away the toner excessively adhered onto the outer circumference of the developer roller  120  so as to form a toner layer having a predetermined thickness. 
     Here, a length L 2  of the developer roller  120  is smaller than an inner distance L 1  between the right and left walls  104  of the housing  100 , and a length L 3  of the bladed  130  is smaller than the length L 2  of the developer roller  120 . Thus, the toner may leak through gaps between right and left ends  121  of the developer roller  120  and the insides  102  of the right and left walls  104  of the housing  100 , and gaps between the blade  130  and the insides  102  of the right and left walls  104  of the housing  100 . Therefore, in order to prevent leakage of the toner, the sealing members  140  are disposed on the insides  102  of the right and left walls  104  of the housing  100 . 
     Since the sealing members  140  are generally formed of a sponge material, the sealing members  140  elastically and closely contact the outer circumference of the developer roller  120 , the blade  130 , and the insides  102  of the right and left walls  104  of the housing  100 . 
     According to the above-described structure, when the sealing members  140 , the blade  130 , and the developer roller  120  are sequentially combined with the housing  100 , the sealing members  140  closely contact the insides  102  of the right and left walls  104  of the housing  100 , the outer circumference of the developer roller  120 , and the blade  130 . Thus, gaps between the right and left ends  121  of the developer roller  120  and the insides  102  of the right and left walls  104  of the housing  100 , and gaps between the blade  130  and the insides  102  of the right and left walls  104  of the housing  100  are blocked to prevent leakage of the toner. 
     As described above, the length L 2  of the developer roller  120  is smaller than the inner distance L 1  between the right and left walls  104  of the housing  100 , and the length L 3  of the blade  130  is smaller than the length L 2  of the developer roller  120 . Thus, a contact width T 2  between the blade  130  and the sealing member  140  is smaller than a width T 1  of the sealing member  140 . 
     FIG. 2A is a partial perspective view of the assembled conventional developing apparatus of FIG. 1, and FIG. 2 is an enlarged view of portion C of FIG.  2 A. FIG. 3A is a cross-sectional view along cutting plane line A-A′ of FIG. 2A, and FIG. 3B is an enlarged view of portion D of FIG.  3 A. 
     As shown in FIGS. 2A,  2 B,  3 A, and  3 B, lower portions of a front part  141  (shown in FIG. 1) of the sealing members  140  closely contact the outer circumference of the developer roller  120 , and upper portions of the front part  141  of the sealing members  140  closely contact an inside surface  131  (shown in FIG. 1) of the blade  130  by the contact width T 2 . 
     A lower long side part  133  of the blade  130  has a bent portion  134 , perpendicular to the long side part  133 , in order to prevent the outer circumference of the developer roller  120  from being damaged due to contact with the blade  130 . Since the bent portion  134  raises the sealing member  140 , the sealing member  140  does not contact the outer circumference of the developer roller  120  at a portion in which the bent portion  134  is formed, thereby forming a gap  160 . Reference character “a” of FIG. 2B represents a portion of the sealing member  140  which does not contact the blade  130 , but is pulled and deformed in a direction  145  due to a portion of the sealing member  140  that contacts the blade  130  to be compressed, thereby forming a gap  150  between the sealing member  140  and the outer circumference of the developer roller  120 . As a result of the above, the toner in the housing  100  may leak through gaps  160  and  150 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an aspect of the present invention to provide a developing apparatus having a sealing member which prevents deterioration of the sealing member due to compression and deformation of the sealing member. 
     Additional 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. 
     The foregoing and/or other aspects of the present invention are achieved by providing a developing apparatus including a housing, a developer roller, a blade, and sealing members. The housing contains toner. The developer roller is combined with the housing to rotate and adheres the toner onto an outer circumference thereof to supply the toner out of the housing. The blade controls an amount of toner that is adhered onto the outer circumference of the developer roller. The sealing members are installed on both inside walls of the housing and closely contact the housing, the developer roller, and the blade to prevent the toner from leaking out. The sealing members include a first sealing member and a second sealing member. The first sealing member has a side part that elastically and closely contacts the inside walls of the housing and a short side part of the blade, and a front part that elastically and closely contacts the outer circumference of the developer roller. The second sealing member overlaps with the first sealing member and has a front part that elastically and closely contacts an inside surface of the blade and the outer circumference of the developer roller. 
     According to an aspect of the invention, the second sealing member further includes a horizontal slit which is cut along a contact line with a lower long side part of the blade. The horizontal slit is cut at least to a depth in which the second sealing member is compressed when the blade is combined with the housing. The second sealing member overlaps with and is attached to the first sealing member. 
     According to an aspect of the invention, the developing apparatus includes the sealing member having a side part, a front part, and a vertical slit. The side part closely contacts the inside walls of the housing. The front part has an upper portion that partially overlaps with and elastically and closely contacts an inside surface of the blade, and a lower portion that elastically and closely contacts the outer circumference of the developer roller. The vertical slit is cut along a short side part of the blade at least up to a lower long side part of the blade. 
     According to an aspect of the invention, the sealing member further includes a horizontal slit which is cut along a contact line with the lower long side part of the blade to the short side part of the blade. 
     According to an aspect of the invention, the vertical slit is cut at least to a depth in which the sealing member is compressed when the blade is combined with the housing. 
     According to another aspect of the invention, the horizontal slit is cut at least to a depth in which the sealing member is compressed when the blade is combined with the housing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and/or other aspects and advantages of the invention will become apparent and more appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
     FIG. 1 is an exploded perspective view of a conventional developing apparatus having sealing members; 
     FIG. 2A is a partial perspective view of the assembled conventional developing apparatus of FIG. 1; 
     FIG. 2B is an enlarged view of portion C of FIG. 2A; 
     FIG. 3A is a cross-sectional view along cutting plane line A-A′ of FIG. 2A; 
     FIG. 3B is an enlarged view of portion D of FIG. 3A; 
     FIG. 4 is an exploded perspective view of a developing apparatus having sealing members, according to an embodiment of the present invention; 
     FIG. 5A is a partial perspective view of the assembled developing apparatus of FIG. 4; 
     FIG. 5B is an enlarged view of portion E of FIG. 5A; 
     FIG. 6A is a cross-sectional view along cutting plane line B-B′ of FIG. 5A; 
     FIG. 6B is an enlarged view of portion F of FIG. 6A; 
     FIG. 7 is a perspective view of a sealing member, according to another embodiment of the present invention; 
     FIG. 8A is a cross-sectional view showing a sealed state of a developing apparatus, according to the present invention, using the sealing member shown in FIG. 7; 
     FIG. 8B is an enlarged view of portion G of FIG. 8A; 
     FIG. 9 is a perspective view of a sealing member, according to another embodiment of the present invention; and 
     FIG. 10 is a perspective view of a sealing member, according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     FIG. 4 is an exploded perspective view of a developing apparatus having sealing members, according to an embodiment of the present invention. As shown in FIG. 4, the developing apparatus includes a housing  400 , a developer roller  420 , a blade  430 , and first and second sealing members  440  and  450 . 
     First, the respective first and second sealing members  440  and  450  are overlapped and then are symmetrically combined with insides  402  of right and left walls  404  of the housing  400  that contain toner. Sides of the first sealing members  440  closely contact the insides  402  of the right and left walls  404  of the housing  400 , respectively. Front parts  441  of the first sealing members  440  are elastically compressed and closely contact an outer circumference of the developer roller  420  when the developer roller  420  is combined with the housing  400 . Front parts  451  of the second sealing members  450  are elastically compressed and closely contact the outer circumference of the developer roller  420  and an inside surface  431  of the blade  430  when the developer roller  420  and the blade  430  are combined with the housing  400 . 
     A thickness T 3  of the first sealing members  440  is predetermined so that an inner distance L 4  between the first sealing members  440  that are disposed on right and left sides of the housing, is equal to or slightly smaller than a length L 3  of the blade  430 . A thickness T 4  of the second sealing members  450  is predetermined so that an inner distance L 5  between the second sealing members  450  that are disposed on right and left sides of the housing, is slightly greater than an effective image width L 6 . Here, the effective image width L 6  represents a width of an image which is formed in an image forming apparatus (not shown). 
     The first and second sealing members  440  and  450  are preferably formed of an elastically deformable material (for example, a sponge). 
     Further, the blade  430  is combined with the housing  400 . The blade  430 , which scrapes away the toner excessively adhered onto the outer circumference of the developer roller  420  so as to form a toner layer having a predetermined thickness, applies a predetermined pressure to the outer circumference of the developer roller  420  to elastically and closely contact the outer circumference of the developer roller  420 . Since the inner distance L 4  between the first sealing members  440  is equal to or slightly smaller than the length L 3  of the blade  430 , right and left short side parts  432  of the blade  430  elastically and closely contact inner surfaces of the first sealing members  440 . 
     The inner surface  431  of the blade  430  contacts the front parts  451  of the second sealing members  450  by the thickness T 4  of the second sealing members  450 . Here, when the second sealing members  450  are elastically compressed, the inner surface  431  of the blade  430  closely contacts the front parts  451  of the second sealing members  450 . 
     The developer roller  420  is combined with couplings  401  which are disposed in the right and left sides of the housing  400 . Here, the front parts  441  and  451  of the first and second sealing members  440  and  450  are elastically compressed and closely contact the outer circumference of the developer roller  420 . Also, a lower long side part  433  of the blade  430  elastically contacts the outer circumference of the developer roller  420 . 
     FIG. 5A is a partial perspective view of the assembled developing apparatus of FIG. 4, and FIG. 5B is an enlarged view of portion E of FIG.  5 A. FIG. 6A is a cross-sectional view along cutting plane line B-B′ of FIG. 5A, and FIG. 6B is an enlarged view of portion F of FIG.  6 A. 
     Referring to FIGS. 5A,  5 B,  6 A, and  6 B, a lower portion of the front part  441  (show in FIG. 4) of the first sealing member  440  is pushed and compressed by the outer circumference of the developer roller  420 , to elastically and closely contact the outer circumference of the developer roller  420 . Upper and lower portions of the front part  451  (shown in FIG. 4) of the second sealing member  450  are compressed by the blade  430  and the outer circumference of the developer roller  420 , respectively, to elastically and closely contact the blade  430  and the outer circumference of the developer roller  420 . 
     Here, the lower long side part  433  of the blade  430  has a bent portion  434  which does not allow the second sealing member  450  to closely contact the developer roller  420 . As a result, a gap  460  may be formed between the second sealing member  450  and the developer roller  420 . 
     However, the first sealing member  440  closely contacts the second sealing member  450 , and as represented by reference character “b” of FIG. 5, the first sealing member  440  contacts the short side part  432  (shown in FIG. 4) of the blade  430 . Thus, the toner does not leak out of the housing  400 , except for toner which is supplied to a photoreceptor drum (not shown) via a contact portion between the outer circumference of the developer roller  420  and the blade  430 . 
     FIG. 7 is a perspective view of a sealing member, according to an embodiment of the present invention. FIG. 8A is a cross-sectional view showing a sealed state of a developing apparatus, according to the present invention, using the sealing member shown in FIG.  7 . FIG. 8B is an enlarged view of portion G of FIG.  8 A. 
     Referring to FIGS. 7,  8 A, and  8 B, a second sealing member  500  has a horizontal slit  480  cut along a contact line between the developer roller  420  and the lower long side part  433  of the blade  430 . 
     In the above-described structure according to the embodiment as shown in FIG. 7, a front part  501  of the second sealing member  500  may be divided into upper and lower portions. Thus, since the bent portion  434  of the lower long side part  433  of the blade  430  is inserted into the horizontal slit  480 , a gap  490 , which is formed between the second sealing member  500  and the outer circumference of the developer roller  420 , may be removed or minimized. The horizontal slit  480  is cut at least to a depth D 1  in which the second sealing member  500  is compressed when the blade  430  is combined with the housing  400 . Here, the first and second sealing members  440  and  500  may be attached to overlap each other, and then combined with the housing  400 . 
     FIG. 9 is a perspective view of a sealing member, according to another embodiment of the present invention. Referring to FIG. 9, sealing members  600 , which may perform the same functions as those of both the first and second sealing members  440  and  450 , are symmetrically combined with the insides  402  of the right and left walls  404  of the housing  400  containing the toner. One side of the sealing members  600  closely contacts the inside  402  of the sidewall  404  of the housing  400 . An upper portion of a front part  920  partially overlaps with and elastically and closely contacts the inside surface  431  of the blade  430 . A lower portion of the front part  920  elastically and closely contacts the outer circumference of the developer roller  420 . Also, the sealing member  600  has a vertical slit  910  cut along the short side part  432  of the blade  430  at least up to the lower long side part  433  of the blade  430 . 
     Here, it is preferable that a thickness T 5  of the sealing member  600  is equal to a value obtained by adding the thickness T 3  of the first sealing member  440  (shown in FIG. 4) and the thickness T 4  of the second sealing member  450  (shown in FIG.  4 ). Thus, the sealing member  600  and the blade  430  overlap each other by the thickness T 4  of the second sealing member  450 . 
     It is also preferable that the vertical slit  910  is cut at least to a depth D 1  in which the front part  920  of the sealing member  600  is compressed when the blade  430  is combined with the housing  400 . 
     In the above-described structure according to the embodiment as shown in FIG. 9, when the sealing member  600 , the blade  430 , and the developer roller  420  are combined with the housing  100 , the sealing member  600  elastically and closely contacts the outer circumference of the developer roller  420  and the blade  430 . Here, as described with reference to FIGS. 6A and 6B, due to the bent portion  434  of the long side part  433  of the blade  430 , the sealing member  600  does not closely contact the developer roller  420  to thereby form a gap therebetween. However, since the sealing member  600  has the vertical slit  910 , the short side part  432  of the blade  430  closely contacts a side  930  which is formed due to the vertical slit  910 . As a result, the toner does not leak out of the housing  400 . In other words, by forming the vertical slit  910  in the single sealing member  600 , as described with reference to FIGS. 5A and 6A, the sealing member  600  produces the same effect as that of including the first and second sealing members  440  and  450 . 
     FIG. 10 is a perspective view of a sealing member, according to another embodiment of the present invention. As shown in FIG. 10, a sealing member  700  is the same as the sealing member  600  shown in FIG. 9 except that it further has a horizontal slit  950  which is cut along the contact line with the lower long side part  433  of the blade  430  up to the short side part  432  of the blade  430 . It is preferable that the horizontal slit  950  is cut at least to the same depth D 1  as the vertical slit  910 . Accordingly, the single sealing member  700  produces the same effect as described with reference to FIGS. 8A and 8B. 
     As described above, in a developing apparatus according to the present invention, a close contact property among a sealing member, a developer roller, and a blade may be improved in order to minimize a gap formed around a contact line between the blade and the developer roller, and to prevent toner from leaking through the gap. 
     Although a few preferred 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.