Abstract:
An optical-scanning apparatus is disclosed. In at least one embodiment, the optical-scanning apparatus includes a light deflector to deflect a beam from a light source; and an optical housing including a scanning-image optical system to focus the beam to scan a photo conductive photo receptor therewith as a light spot. The optical housing includes a collection member to collect particulate materials. The collection member includes a structure combining or overlapping plural sheet-shaped members, each including a highly-chargeable electrostatic absorption filter. Alternatively, the collection member includes an electrostatic absorption filter and a breathable sheet-shaped member covering almost all the surface of the electrostatic absorption filter.

Description:
PRIORITY STATEMENT 
       [0001]    This patent application is based on, and hereby claims priority under 35 U.S.C. §119 on Japanese patent application Nos. 2006-123524 filed on Apr. 27, 2006 and 2006-123525 filed on Apr. 27, 2006, each filed in the Japan Patent Office, the entire contents of which each of which is hereby incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present application generally relate to an optical-scanning apparatus and/or to an image forming apparatus using the optical-scanning apparatus. For example, they may relate to an optical-scanning apparatus deflecting a beam from a light source with a light deflector, focusing the beam with a scanning-image optical system installed at an optical housing, and scanning a photoconductive photoreceptor with the focused beam as a light spot. 
         [0004]    2. Discussion of the Background 
         [0005]    Recently, image forming apparatuses such as laser printers and digital copiers using the above-mentioned optical-scanning apparatus have come to be known well. Such an image forming apparatus uses, e.g., a polygon mirror  100  having the planar shape of an equilateral hexagon as shown in  FIG. 15 . The polygon mirror  100  rotates anticlockwise in the direction of an arrow, and there is a turbulence due to a negative-pressure of air then. The turbulence flings dusts and particulate materials in the air down to a part A behind each of the corners of the polygon mirror  100  to the rotation direction thereof, resulting in contamination of the part A. When the surface of the polygon mirror  100  is contaminated, a reflectance thereof deteriorates resulting in deterioration of image quality. 
         [0006]    Japanese Patent No. 3652238 discloses a method of using a part B comparatively less contaminated instead of the part A to perform synchro detection for controlling irradiation timing in the main scanning direction. 
         [0007]    Published Unexamined Japanese Patent Application No. 11-218710 discloses a method of discharging the polygon mirror so as not to attract dusts. 
         [0008]    However, in the method disclosed in Japanese Patent No. 3652238, the contamination of the polygon mirror is inevitable as time passes, and cleaning or exchange thereof is needed. Further, the method disclosed in Published Unexamined Japanese Patent Application No. 11-218710 is insufficient because of not removing the cause of the contamination, but just attracting fewer dusts. 
         [0009]    Because of these reasons, a need exists for an optical-scanning apparatus and an image forming apparatus wherein the contamination of polygon mirror can be largely reduced. 
       SUMMARY OF THE INVENTION 
       [0010]    Accordingly, at least one embodiment of the present application provides an optical-scanning apparatus wherein the contamination of polygon mirror can be largely reduced. 
         [0011]    At least one embodiment of the present invention provides an image forming apparatus using the optical-scanning apparatus. 
         [0012]    In at least one embodiment of the present invention, an optical-scanning apparatus includes: 
         [0013]    a light deflector to deflect a beam from a light source; and 
         [0014]    an optical housing including a scanning-image optical system to focus the beam to scan a photoconductive photoreceptor therewith as a light spot, 
         [0015]    wherein the optical housing includes a collection member to collect particulate materials, and wherein the collection member includes a structure combining plural sheet-shaped members, each including a highly-chargeable electrostatic absorption filter. 
         [0016]    In addition, in at least one embodiment, an optical-scanning apparatus includes: 
         [0017]    a light deflector to deflect a beam from a light source; and 
         [0018]    an optical housing including a scanning-image optical system to focus the beam to scan a photoconductive photoreceptor therewith as a light spot, 
         [0019]    wherein the optical housing includes a collection member to collect particulate materials, and wherein the collection member includes: 
         [0020]    an electrostatic absorption filter; and 
         [0021]    a breathable sheet-shaped member to cover almost all the surface of the electrostatic absorption filter. 
         [0022]    These and other features and advantages of embodiments of the present invention will become apparent upon consideration of the following description of the example embodiments of the present invention taken in conjunction with the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Various other features and attendant advantages of embodiments of the present invention will be more fully appreciated as the same becomes better understood from the detailed description when considered in connection with the accompanying drawings in which like reference characters designate like corresponding parts throughout and wherein: 
           [0024]      FIG. 1  is a schematic view illustrating a cross-section of the image forming apparatus of an embodiment of the present invention; 
           [0025]      FIG. 2  is an enlarged view illustrating an image reader of the image forming apparatus in  FIG. 1 ; 
           [0026]      FIG. 3  is a perspective view illustrating a laser beam scanner of the image forming apparatus; 
           [0027]      FIG. 4A  is a front view illustrating a constitution of the collection member of an embodiment of the present invention; 
           [0028]      FIG. 4B  is a perspective view illustrating another constitution of the collection member of an embodiment of the present invention; 
           [0029]      FIG. 5  is a plain view illustrating an embodiment of the collection member of the present invention; 
           [0030]      FIGS. 6A and 6B  are a sectional view and a plain view of another embodiment of the collection member of the present invention, respectively; 
           [0031]      FIGS. 7A and 7B  are a sectional view and a plain view of a further embodiment of the collection member of the present invention, respectively; 
           [0032]      FIG. 8  is a sectional view illustrating the collection member in  FIG. 4B  of an embodiment of the present invention, opening its opening mouth; 
           [0033]      FIG. 9  is a sectional view illustrating the collection member in  FIG. 4B  of an embodiment of the present invention, closing its mouth; 
           [0034]      FIG. 10  is a plain view illustrating an embodiment of locating the collection member in  FIG. 4A  of the present invention; 
           [0035]      FIG. 11  is a sectional view illustrating another embodiment of locating the collection member in  FIG. 4A  of the present invention; 
           [0036]      FIG. 12  is a sectional view illustrating an embodiment of locating the collection member in  FIG. 4B  of the present invention; 
           [0037]      FIG. 13  is a sectional view illustrating another embodiment of locating the collection member in  FIG. 4B  of the present invention; 
           [0038]      FIG. 14  is a plain view illustrating a further embodiment of the collection member of the present invention; and 
           [0039]      FIG. 15  is a plain view illustrating a polygon mirror in the image forming apparatus of an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0040]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0041]    In describing example embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. 
         [0042]    Referencing the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, example embodiments of the present patent application are hereafter described. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0043]    Embodiments of the present invention provides an optical-scanning apparatus and an image forming apparatus wherein the contamination of polygon mirror can be largely reduced. 
         [0044]      FIG. 1  is a schematic view illustrating a cross-section of the image forming apparatus of an embodiment of the present invention. 
         [0045]    The image forming apparatus, i.e., a digital copier in  FIG. 1  includes an image reader  1 , a printer  2  having a laser beam scanner, and an automatic document feeder  3 . The document feeder feeds originals to set them on a contact glass  4  one by one, and discharges the originals thereon after duplicated. 
         [0046]      FIG. 2  is the image reader  1  having a first carriage A including a light source formed of an illumination lamp  5  and a reflector  6 , and a first mirror  7 , and a second carriage B including a second mirror  8  and a third mirror  9 . When an original is read, the first carriage A moves forward at a constant speed, followed by the second carriage B at a half speed of the first carriage A, to optically scan the original. The original on the contact glass  4  is illuminated by the illumination lamp  5  and reflector  6 , and a reflected image thereof is focused on a CCD sensor  12  by a lens  11  through the first mirror  7 , second mirror  8 , third mirror  9  and a color filter  10 . The CCD sensor  12  photoelectrically converts the reflected image to produce an analog image signal. After the analog image signal is produced, the first carriage A and second carriage B returns to their original positions. 
         [0047]    Being a three-line CCD having a red filter, a green filter and a blue filter, the CCD sensor can read a full-color original. Numeral  14  is a fan internally cooling the image reader  1 . The analog image signal from the CCD sensor  12  is converted by an analog/digital converter to a digital image signal, and the digital image signal is subjected to various image processes such as a digitalization process, a multilevel process, a gradation process, a variable power process and an editing process on an image processing board  13 . 
         [0048]    In the printer  2 , a photoreceptor drum  15  as an image bearer is driven to rotate and uniformly charged with a charger  16 , and the digital image signal processed with the image processing board  13  is transferred to a semiconductor driving board (not shown). A laser beam scanner  17  as an optical-scanning apparatus irradiates the photoreceptor drum  15  with image wise light based on the digital image signal to form an electrostatic latent image thereon. Then, the electrostatic latent image on the photoreceptor drum  15  is developed by an image developer  18 . 
         [0049]    A transfer sheet is fed to a registration roller  26  from one of paper feeders  23  to  35 , and timely sent out by the registration roller  26  to match a visual image on the photoreceptor drum  15 , and which is transferred onto the transfer sheet by a transferer  20 . The transfer sheet is separated from the photoreceptor drum  15  by a separator  21 , transported by a transporter  27 , and discharged on a tray  29  as a duplicate after the visual image is fixed thereon. The photoreceptor drum  15  is cleaned by a cleaner  22  to remove a toner remaining thereon after the transfer sheet is separated therefrom. 
         [0050]    The laser beam scanner  17  includes, as  FIG. 3  shows, a semiconductor laser unit  30 , a cylindrical lens  31 , a polygon mirror  32 , a fθ lens  34 , a reflector  35  and a dust-proof glass  36  in an optical housing, and the top of which is covered by a cover  41  such that the optical housing is almost sealed. 
         [0051]    In the laser beam scanner  17 , a laser beam emitted from a semiconductor laser in the semiconductor laser unit  30  is changed to a parallel flux through a collimated lens therein, and the parallel flux is passed through an aperture therein to have a specific shape. The flux is compressed in the vertical scanning direction through the cylindrical lens  31 , and falls on the polygon mirror  32 . The polygon mirror  32  has the shape of a regular polygon and is unidirectionally rotated at a constant speed by a polygon motor  33 . The rotation speed of the polygon mirror  32  depends on the rotation speed of the photoreceptor drum  15 , the writing density of the laser beam scanner  17  and the number of faces of the polygon mirror  32 . 
         [0052]    The laser beam fallen on the polygon mirror  32  from the cylindrical lens  31  is deflected by a reflecting surface of the polygon mirror  32 , and fallen on the fθ lens  34 . The fθ lens  34  converts scanning light having a constant angular speed from the polygon mirror  32  so as to be scanned at a constant speed on the photoreceptor drum  15 , and the laser beam from the fθ lens  34  is focused on the photoreceptor drum  15  through the reflector  35  and dust-proof glass  36 . The fθ lens  34  also has a capability of adjusting a deviation of optical plane. The laser beam passed through the fθ lens  34  is reflected by synchro detection mirror  37  outside an image area and led to a synchro detection sensor  38 . Then, the synchro detection sensor  38   a  produces a synchro signal which is a cue standard of the main scanning direction. 
         [0053]    The laser beam scanner  17  includes many optical parts having optical capabilities which noticeably deteriorate when particulate materials in the air adhere thereto. Particularly, particulate materials included in the air in the optical unit tend to adhere to the polygon mirror  32  rotating at a high speed. Not simply the reflectance thereof deteriorates, but the reflectance in the main scanning direction mostly deteriorates because the rotation direction mostly conforms thereto, resulting in uneven image density. 
         [0054]    This problem can be reduced by an electrostatic absorption filter collecting powder dusts and particulate materials. The electrostatic absorption filter is formed of a fibrous member, and the dust collectability thereof can be increased when becoming more short-chained because of being highly-charged. However, when a highly-charged electrostatic absorption filter is used to efficiently collect dusts, a fibrous member forming the filter more possibly drops due to air stream, gravity, vibration, etc. When the fibrous member drops, scatters and adheres to lenses in the optical-scanning apparatus, the resultant images are seriously deteriorated. 
         [0055]      FIG. 4A  is a front view illustrating a constitution of the collection member of an embodiment of the present invention. 
         [0056]    The collection member  50  has a structure combining plural sheet-shaped members each including a highly-chargeable electrostatic absorption filter  51  to collect particulate materials. The highly-chargeable electrostatic absorption filter  51  is sandwiched by two pieces of breathable antiscattering sheets  52  and  53 , which prevents the fibrous member of the highly-chargeable electrostatic absorption filter  51  from scattering due to air stream, gravity, vibration, etc. 
         [0057]    Next, other embodiments of the collection member  50  will be explained, referring to  FIGS. 5 ,  6 A,  6 B,  7 A and  7 B. 
         [0058]    A collection member  50  in  FIG. 5  has a constitution formed by casting plural sheets and a frame  60 . Namely, the collection member  50  has a constitution formed by casting a highly-chargeable electrostatic absorption filter  51  sandwiched by two pieces of breathable antiscattering sheets  52  and  53  and the frame  60 . Therefore, the antiscattering sheets  52  and  53  prevent the fibrous member of the highly-chargeable electrostatic absorption filter  51  in the collection member  50  from scattering. 
         [0059]    Such a collection member  50  is detachable from an optical housing through the frame  60 , which costs less than the collection member wherein a frame is placed on sheets afterwards. 
         [0060]    A collection member  50  in  FIGS. 6A and 6B  has a constitution formed by fastening several places  54  of the circumference of a highly-chargeable electrostatic absorption filter  51  sandwiched by two pieces of breathable sheets  52  and  53 . The fastening method includes methods of welding or physically pressurizing such as caulking. Further, methods of using other members such as a stapler, a grommet, a rivet and a clip can also be used, and which depend on the shape and material of the collection member  50 , methods of setting the laser beam scanner  17  in the optical housing, etc. 
         [0061]    A collection member  50  in  FIGS. 7A and 7B  also has a constitution formed by fastening several places  54  of the circumference of a highly-chargeable electrostatic absorption filter  51  sandwiched by two pieces of breathable sheets  52  and  53 . The fastening methods used in for the collection member  50  in  FIGS. 6A and 6B  can be used, however, the collection member  50  in  FIGS. 7A and 7B  differs therefrom in that the circumference is wholly fastened. Namely, the whole circumference  54  is fastened. 
         [0062]    Any sheets can be used for the sheets  52  and  53  if breathable, sheet-shaped and capable of preventing the fibrous member of the highly-chargeable electrostatic absorption filter  51  from scattering. However, the sheets  52  and  53  are preferably meshed materials having good breathability. The sheets  52  and  53  may be electrostatic absorption filters having lower chargeability than the highly-chargeable electrostatic absorption filter  51 . Typically, most of the highly-chargeable electrostatic absorption filters include shot-chained fibers, and which tend to drop, fall and scatter due to external forces. Meanwhile, the low-chargeable electrostatic absorption filter not including such a shot-chained fiber can sufficiently be used as an antiscattering sheet. In addition, the low-chargeable electrostatic absorption filter can trap particulate materials in the air although less than the highly-chargeable electrostatic absorption filter  51 . 
         [0063]    Next, the location of the collection member  50  in the optical housing will be explained. 
         [0064]    The electrostatic absorption filter is typically used with a fan and a duct, and collects dusts included in a gas passing the filter, and further collects particulate materials with static electricity. In an embodiment of the present invention, a fan or a duct is not used and the air from an airstream caused by the rotation of the polygon mirror  32  does not pass the collection member much. However, the highly-chargeable electrostatic absorption filter  51  can collect particulate materials in the optical housing without a fan or a duct. Therefore, the collection member  50  can trap particulate materials anywhere in the optical housing. 
         [0065]    The collection member  50  is preferably located close to the polygon mirror  32  to more efficiently prevent contamination thereof. Particularly, as shown in  FIG. 10 , when the collection member  50  is located facing the mirror of the polygon mirror  32 , the airstream caused by the rotation thereof directly hits the collection member  50 , and therefore particulate materials can efficiently be collected. 
         [0066]    The collection member  50  may even be located above the polygon mirror  32  as shown in  FIG. 11 , which also effectively collects particulate materials to prevent contamination of the polygon mirror  32 . 
         [0067]      FIG. 14  is a collection member including sheets  52  and  53  which are both electrostatic absorption filters and antiscattering sheets, and a net-shaped member  55  reinforcing the sheets  52  and  53 . The net-shaped member  55  is combined with the sheets  52  and  53  to reinforce them and prevent members forming the sheet such as a fibrous member from dropping, falling and scattering due to external forces. Therefore, handling the filter becomes easier, the choice of the antiscattering sheets increases and the design of the collection member becomes simpler. 
         [0068]    In  FIG. 14 , since the net-shaped member  55  covers one side of the sheet  52  or  53 , the backside of the sheet  53  where a member forming the collection member tends to scatter due to gravity, airstream, vibration, etc. is covered thereby. 
         [0069]      FIG. 4B  is a perspective view illustrating another constitution of the collection member  50  of an embodiment of the present invention, which contains a highly-chargeable electrostatic absorption filter  51  collecting particulate materials in a bag-shaped member  52 . The bag-shaped member  52  is a nonwoven cloth formed of a chemical fiber made of polypropylene in  FIG. 4B , however, may be other nonwoven clothes formed of chemical fibers such as polyethylene and rayon, and may be coarse-textured clothes formed of biological materials such as paper, cotton and silk as used for tea-bags. It is essential that the bag-shaped member  52  does not drop a fiber of the highly-chargeable electrostatic absorption filter  51  in an optical-scanning apparatus and has a mesh size so as to pass the particulate materials to be collected. 
         [0070]    The highly-chargeable electrostatic absorption filter  51  is placed in the bag-shaped member  52  through an opening thereof, and the opening thereof is closed to form the collection member  50 . The opening of the bag-shaped member  52  is typically closed with an adhesive, and may be closed with other members such as a stapler and a clip. Any of these methods take time and cost as much. 
         [0071]      FIG. 8  is the collection member  50 , the opening of which is easily closable without using fastening members such as an adhesive and a stapler. 
         [0072]    The bag-shaped member  52  in  FIG. 8  is made of a large-mesh paper as used for tea-bags, which has an opening  53  through which the electrostatic absorption filter  51  is placed therein. The bag-shaped member  52  also has a turnback  54  like a pocket, having the same width of the bag-shaped member  52  and a side fixed on a side thereof. 
         [0073]    As shown in  FIG. 9 , the turnback  54  can easily be turned back after the electrostatic absorption filter  51  is placed in the bag-shaped member  52  because of being made of a flexible material such as a paper, and which covers the opening  53  to close the bag-shaped member  52 . Therefore, the opening  53  can be closed without using an adhesive or a stapler, and falling of a fiber from the electrostatic absorption filter  51  can be prevented. The turnback  54  is reopened to exchange the electrostatic absorption filter  51 . 
         [0074]    Next, the location of, and a method of locating the collection member  50  in the optical housing will be explained. Since the optical housing includes an almost sealed space, the collection member  50  can effectively be located anywhere therein. The collection member  50  is preferably located close to the polygon mirror  32  to more efficiently prevent contamination thereof. Including the electrostatic absorption filter  51  in the bag-shaped member  52 , the collection member  50  can be pasted on any place of a chassis  41  of the optical housing  40  as shown in  FIG. 12 . In addition, the collection member  50  can be pasted on a cover  42  of the optical housing  40  as shown in  FIG. 12 . 
         [0075]    The collection member  50  including the electrostatic absorption filter  51  is more effectively used when the electrostatic absorption filter  51  has a larger collection area exposed to air. Therefore, when the bag-shaped member  52  is pasted on the chassis  41  or on the cover  42 , there is no space therebetween, resulting in deterioration of collectability. 
         [0076]    As shown in  FIG. 13 , holders  43  and  44  are located on the chassis  41  and/or the cover  42  of the optical housing  40 , which each includes the collection member  50  to limit movement thereof. Further, the holders  43  and  43  each has projections  45  on which the collection member  50  is located such that a space is formed between the collection member  50  and the chassis  41  and/or the cover  42 . Therefore, the collection area exposed to air of the electrostatic absorption filter  51  increases and particulate materials are more efficiently collected. 
         [0077]    Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit and scope of the invention as set forth therein. 
         [0078]    Further, elements and/or features of different example embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims. 
         [0079]    Still further, any one of the above-described and other example features of the present invention may be embodied in the form of an apparatus, method, system, computer program and computer program product. For example, of the aforementioned methods may be embodied in the form of a system or device, including, but not limited to, any of the structure for performing the methodology illustrated in the drawings. 
         [0080]    Even further, any of the aforementioned methods may be embodied in the form of a program. The program may be stored on a computer readable media and is adapted to perform any one of the aforementioned methods when run on a computer device (a device including a processor). Thus, the storage medium or computer readable medium, is adapted to store information and is adapted to interact with a data processing facility or computer device to perform the method of any of the above mentioned embodiments. 
         [0081]    The storage medium may be a built-in medium installed inside a computer device main body or a removable medium arranged so that it can be separated from the computer device main body. Examples of the built-in medium include, but are not limited to, rewriteable non-volatile memories, such as ROMs and flash memories, and hard disks. Examples of the removable medium include, but are not limited to, optical storage media such as CD-ROMs and DVDS; magneto-optical storage media, such as MOs; magnetism storage media, including but not limited to floppy disks (trademark), cassette tapes, and removable hard disks; media with a built-in rewriteable non-volatile memory, including but not limited to memory cards; and media with a built-in ROM, including but not limited to ROM cassettes; etc. Furthermore, various information regarding stored images, for example, property information, may be stored in any other form, or it may be provided in other ways. 
         [0082]    Example embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.