Patent Publication Number: US-9429896-B2

Title: Cover movement mechanism, and image forming apparatus provided with the cover movement mechanism

Description:
This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2014-056576 filed on Mar. 19, 2014. The entire subject matter of the application is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosures relate to a cover movement mechanism and an image forming apparatus provided with the cover movement mechanism. More particularly, the present disclosures relate to the cover movement mechanism with which a damage of a cover provided to the image forming apparatus or the like can be avoided. 
     2. Related Art 
     Conventionally, image forming apparatuses provided with openable covers have been known. In such an image forming apparatus, in order to prevent the cover from being damaged when a user attempts to open the same beyond an openable range thereof may be provided. One example of a conventional cover movement mechanism is configured such that a rotational shaft, which rotationally supports the cover, is provide. The rotation shaft is held by bearings, and shaft cover pieces which press-holds the rotational shaft in the respective bearings are provided. When the user attempts to open the cover beyond the openable range, the shaft covers elastically deform and allow the shaft to be released from the bearings. With such a configuration, in an exemplary conventional art, the damage of the cover can be prevented. 
     SUMMARY 
     Even in the above-described configuration, if the user attempts to open the cover with a finger, a part of cloths or the like being sandwiched between a base part, to which the cover is attached, and the cover (i.e., with the finger or the like being nipped in the opening formed between the base part and the cover), an unexpected force may be applied to the cover, which may result in a damage of the cover. 
     According to aspects of the disclosure, there is provided a cover movement mechanism, which is provided with a cover configured to rotate, a base part to which the cover is rotatably attached, a holding part configured to contact the cover when the cover is in a first opened state in which the cover is rotated to open by a first angle with respect to a closed state of the cover, thereby holding the cover in the first opened state, two shafts having a common axis and provided to one of the cover and the base part, two bearings configured to receive the two shafts and provided to other one of the cover and the base part, and a releasing mechanism configured to allow at least one of the two shafts to be released from corresponding one of the two bearings when the cover is in a second state in which the cover is rotated to open by a second angle that is smaller than the first angle and an opposing force preventing a rotation of cover acts on the cover. 
     According to aspects of the disclosures, there is also provided an image forming apparatus, provided with a housing, a printing unit configured to form an image on a sheet, a sheet discharging unit configured to discharge the sheet on which the image is printed, and a cover movement mechanism. The cover movement mechanism includes a cover configured to rotate, a base part to which the cover is rotatably attached, a holding part configured to contact the cover when the cover is in a first opened state in which the cover is rotated to open by a first angle with respect to a closed state of the cover, thereby holding the cover in the first opened state, two shafts having a common axis and provided to one of the cover and the base part, two bearings configured to receive the two shafts and provided to other one of the cover and the base part, and a releasing mechanism configured to allow at least one of the two shafts to be released from corresponding one of the two bearings when the cover is in a second state in which the cover is rotated to open by a second angle that is smaller than the first angle and an opposing force preventing a rotation of cover acts on the cover. The cover in the first opened state serves as a printed sheet discharge tray configured to receive the sheet discharged by the sheet discharging unit. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a perspective view of a printer according to aspects of an illustrative embodiment. 
         FIG. 2  is a cross-sectional side view of the printer schematically showing main components of the printer according to aspects of the illustrative embodiment. 
         FIG. 3  is an exploded perspective view of the printer according to aspects of an illustrative embodiment. 
         FIG. 4  is a perspective view of a cover movement mechanism according to aspects of an illustrative embodiment. 
         FIG. 5A  is a plan view of a second cover of the printer according to aspects of an illustrative embodiment. 
         FIG. 5B  is a perspective view of the second cover according to aspects of an illustrative embodiment. 
         FIG. 6  is a perspective view of a shaft schematically showing a shape thereof according to aspects of an illustrative embodiment. 
         FIG. 7A  is a cross-sectional view of a second cover attachment part according to aspects of an illustrative embodiment. 
         FIG. 7B  is a cross-sectional view of the second cover attachment part when the second cover is to be detached according to aspects of an illustrative embodiment. 
         FIG. 8A  is a side view showing a state where the second cover is closed according to aspects of an illustrative embodiment. 
         FIG. 8B  is a side view showing a second open state of the second cover according to aspects of an illustrative embodiment. 
         FIG. 8C  is a side view showing a first open state of the second cover according to aspects of an illustrative embodiment. 
         FIG. 9  is a cross-sectional view of a second cover attachment part according to aspects of another illustrative embodiment. 
         FIG. 10  is a perspective view of a shape of a shaft of the second cover according to aspects of another illustrative embodiment. 
         FIG. 11A  is a side view showing a state where the second cover is closed according to aspects of the other illustrative embodiment. 
         FIG. 11B  is a side view showing a second open state of the second cover according to aspects of the other illustrative embodiment. 
         FIG. 11C  is a side view showing a first open state of the second cover according to aspects of the other illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Hereinafter, referring to the accompanying drawings, a printer according to aspects of illustrative embodiments will be described. In the following description, a printer  1  is described in detail as an example of an illustrative embodiment. According to the illustrative embodiment, the printer  1  is a monochromatic laser printer employing an electrophotographic image forming method. As shown in  FIG. 1 , the printer  1  has a housing  3  which accommodates a printing unit  5 . On a front surface of the housing  3 , a first cover  3 A is attached so as to be rotatable about an axis extending in a width direction. It is noted that directions with respect to the printer  1  are indicated in drawings, and description will be made referring to the directions as indicated.  FIG. 1  shows a state where the first cover  3 A is closed. It is noted that the printer  1  needs not be limited to the monochromatic laser printer, and could be any other printing apparatus, or an image forming apparatus such as a color laser printer, an inkjet printer, an LED (light emitting diode) printer, or the like. 
     On an upper part of the printer  1 , a cover movement mechanism  20  is provided. The cover movement mechanism  20  includes a second cover  21 .  FIG. 1  shows a state where the second cover  21  is opened. 
     As shown in  FIG. 1 , the second cover  21  is configured to cover an upper part of the cover movement mechanism  20 . A rear end part  21 E of the cover  21  is configured to move toward a front side of the cover movement mechanism in accordance with a rotation of the second cover  21 . 
     The second cover  21  is rotatable between a position where the second cover  21  closes the upper side of a discharge part  3 C (i.e., in a closed state) and a position where the upper side of the discharge part  3 C is exposed (i.e., in an open state). The discharge part  3 C is a space arranged on an upper part of the housing  3 . In the discharge part  3 C, as shown in  FIG. 2 , a discharged sheet tray  3 D configured to receive the sheets on which images have been printed and discharged from the housing  3  is provided. 
     When an image formation is executed, the user may rotate the first cover  3 A and the second cover  21  frontward to open the same, and place a sheet on the opened first cover  3 A. When the image formation process is started, the sheet placed on the first cover  3 A is fed toward the printing unit  5  inside the housing  3 , and an image is formed thereon by the printing unit  5 . After the image is formed, the sheet is further conveyed and stacked on a discharge surface  3 E, which is an upper surface of the discharged sheet tray  3 D and on the second cover  21 . That is, when the second cover  21  is in the open state, the surface of the second cover  21  is used as a part of the discharged sheet tray. 
     The printing unit  5  is configured to form (i.e., print) an image on a sheet such as a printing sheet. According to the illustrative embodiment, the printing unit  5  is an electrophotographic image forming unit, and includes a photosensitive drum  5 A, a charging unit  5 B, an exposing unit  5 C, a transferring unit  5 D and a fixing unit  5 E. The discharge surface  3 E is arranged on an upper side with respect to a rotational axis L 1  of the photosensitive drum  5 A. 
     The charging unit  5 B charges the circumferential surface of the photosensitive drum  5 A. The exposing unit  5 C exposes the charged surface of the photosensitive drum  5 A to form an electrostatic latent image thereon. Then, the developing agent (e.g., toner) is applied on the circumferential surface of the photosensitive drum  5 A, and the developing agent is attracted by the electrostatic latent image, thereby a developed image is formed. The transferring unit transfers the developed image (e.g., a toner image) on the sheet. 
     The fixing unit  5 E fixes the developing agent transferred on the sheet thereon. The sheet discharged from the developing unit  5 E is discharged toward the discharge sheet tray  3 D by a discharging roller  7 A as the sheet on which an image has been formed. A pair of pressing rollers  7 B are provided to urge the sheet toward the discharging roller  7 A. With this configuration, the sheet is discharged while a curling tendency of the sheet is corrected. 
     A process casing  5 F accommodating the photosensitive drum  5 A and the exposing unit  5 C, and the printing unit  5  including the fixing unit  5 E and the like are assembled to a main body of the printer  20 . The main body includes components which are not normally detached/attached or decomposed by the user in normal use, and includes the pair of frames  9  and the housing  3  shown in  FIG. 3 . 
     The pair of frames  9  are plate-like components arranged on both sides of the printing unit  6  such as the process casing  5 F. According to the illustrative embodiment, the pair of frames  9  are made of resin, and the printing unit  5  such as the process casing  5 F is supported by the pair of frames  9 . 
     The exposing unit  5 C is held by the plate  9 B shown in  FIG. 2 , and supported by the frames  9 . The plate  9 B is a metal plate member arranged below the discharged sheet tray  3 D, and extends to be bridged between the pair of frames  9  such that both ends, in the extending direction, of the plate  9 B are fixed to the pair of frames, respectively. 
     As shown in  FIG. 3 , the housing  3  is configured such that the pair of frames  9  are covered with exterior covers  3 G- 3 J and the like from outside. The exterior covers  3 G and  3 H are side covers which cover the pair of frames  9  from a width direction. It is noted that the width direction is as indicated in  FIG. 1 , a direction along which the pair of frames  9  face each other. According to the illustrative embodiment, the width direction coincides with the right-and-left direction. The exterior cover  3 J is a top cover that covers the pair of frames  9  from the above. 
     A feeder mechanism  12  is shown in  FIG. 12 . The feeder mechanism  12  is configured to covey the sheet placed on the first cover  3 A toward the printing unit  5 . The feeder mechanism  12  has a pickup roller  12 A and a separation unit  12 B. 
     Among the pickup roller  12 A, and the components configuring the separation unit  12 B, and printing unit  5 , rotating components such as the photosensitive drum  5 A receive a driving force from a driving source (not shown) such as an electrical motor. 
     The pickup roller  12 A is configured to contact a sheet on one side, in a stacking direction, of the plurality of sheets which are stacked, and rotate. If a plurality of sheets are fed by the pickup roller  12 A, the separation unit  12 B functions to separate the plurality of sheets and feed the same one by one toward the printing unit  5 . 
     Further, as shown in  FIG. 1 , on both sides, in the width direction, of the discharge sheet tray  3 D, a pair of bank parts  11  are formed, respectively. Each of the pair of bank parts  11  as a wall  11 A. Each wall  11 A is configured to extend uprightly from the discharge surface  3 E and faces the discharge part  3 C. The walls  11 A, or the pair of bank parts  11  functions to prevent the sheets placed on the discharge surface  3 E from hanging out of the discharge sheet tray  3 D. 
     An outer surface of each of the bank parts  11  including the wall  11 A is composed of the exterior cover  3 J. The upper end portions of the pair of frames  9  are covered with the exterior cover  3 J and located inside the bank parts  11 , respectively. 
     A controller substrate  15  is a substrate on which a controller unit configured to control operations of the printing unit  5  and the driving source  8  and the like is provided. The controller substrate  15  is attached to a plate surface  9 A which is a surface of one of the pair of frames (e.g., the right side frame)  9  opposite to a surface facing the printing unit  5 , that is a surface  9 A facing the exterior cover  3 G. 
     Next, refereeing to  FIGS. 4-8 , the cover movement mechanism  20  will be described.  FIGS. 7A and 7B  are partial cross-sections views taken along line A-A of  FIG. 8B . 
     The cover movement mechanism  20  has, as shown in  FIG. 4 , the second cover  21 , the frames  9 , cover supporting frames  9 D and cover holding parts  25 . 
     The second cover  21  is formed to have a rectangular shape, when viewed from the above, as shown in  FIGS. 5 and 6 , and has cover plate  21 A, and side plates  21 B formed on both sides of the cover plate  21 A. 
     Each side plate  21 B has, as shown in  FIG. 5B , a plate spring part  26  which is defined by forming a slit  21 C. The plate spring part  26  has a movable end  26 A, which is separated from the side plate  21 B with the slit  21 C, and a fixed end connected to the side plate. 
     On a front end part  21 D, which corresponds to a longer side of the second cover  21 , a contacting part  27  configured to contact the cover holding part  25  (described later) is formed. The front end part  21 D defines an opened part  28  in association with the frames  9  when the second cover  21  is closed (see  FIG. 8A ). A width along a narrower side (i.e., in the up-and-down direction in f of the opened part  28  decreases as the second cover  21  is rotated (see  FIGS. 8A and 8B ). 
     On each plate spring part  26 , a shaft  22  is provided. That is, the shaft  22  is provided to the front end part  21 D of the second cover  21 , at a position on a front side of the cover movement mechanism  20 . According to the illustrative embodiment, each shaft  22  is protruded outward from the side plates  21 B of the second cover  21 . In other words, the shaft  22  is provided at a tip end portion on the movable end  26 A side of the plate spring part  26 , and protrudes outward, in an axial direction, from the side plate  21 B of the second cover  21  (see  FIGS. 5A and 5B ). 
     It is noted that the axial direction is a right-and-left direction indicated by an arrow in  FIG. 5A . An expression “protrudes outward, in the axial direction, from the side plate  21 B of the second cover  21 ” means to protrude rightward in  FIG. 5A  with respect to the right one of the side plates  21 B, while means to protrude leftward in  FIG. 5A  with respect to the left one of the side plates  21 B. 
     Each shaft  22  has a hollow cylinder shape as shown in  FIG. 6 , and a truncated part  24  having a tapered shape, is formed on a part of its outer circumferential surface. When the second cover  21  is in a second open state, in which the second cover  21  is opened at a second angle θ 2  (e.g., 30 degrees) which is smaller than a first angle θ 1  (e.g., 150 degrees), if an opposing force that obstructs the rotation of the second cover  21  is applied to the second cover, the truncated parts  24  serve such that at least one of the two shafts  22  is released from the bearing  23  (see  FIGS. 7A and 7B ). It is noted that  FIG. 6  shows the shaft  22  when second cover  21  is in the second open state as shown in  FIG. 8B . 
     As described above, according to the illustrative embodiment, the shafts  22  are formed to protrude outward from side pates  21 B of the second cover  21 , respectively. Accordingly, in comparison with a case where the truncated part  24  is formed on the outer circumferential surface of a shaft protruding inward from the side plate  21 B, it is relatively easy to form the truncated part  24 . 
     It is noted that, according to the illustrative embodiment, the plate spring part  26  is defined by forming the slit  21 C on each side plate  21 B and the shaft  22  is formed on the plate spring part  26 . However, aspects of the disclosures need not be limited to such a configuration. For example, the shaft  22  may be formed on each side plate  21 B. In such case, it is preferable that each side plate  21 B is formed of elastic resin. Further, the truncated part  24  may be formed on only one of the two shafts  22 . Furthermore, the shape of the truncated part  24  may not be limited to the tapered shape. 
     The cover supporting frame  9 D is formed as a part of the frame  9 , as shown in  FIG. 4 , and formed to be a plate-like member extending upward. Each of the cover supporting frame  9 D is formed with the bearing  23 , as shown in  FIGS. 4 and 7A . As the shafts  22  engage with the bearings  23 , respectively, the second cover  21  is coupled to the cover supporting frame  9 D. 
     The cover holding parts  25  hold the second cover  21  to be in the first opened state with respect to the main body, as the cover holding parts  25  contact the contacting parts  27  of the second cover  21  when the second cover  21  is in the first opened state (see  FIG. 8C ) which is a position the second cover  21  has rotated by the first angle θ 1  with respect to the position when the second cover is in the closed state (see  FIG. 8A ). 
     Next, referring to  FIGS. 8A-8C , operations of the cover movement mechanism  20  will be described. 
     When the second cover  21  is in the closed state, as shown in  FIG. 8A , the truncated part  24  is oriented in a direction rotated clockwise by the second angle θ 2  with respect to a vertical direction, or the up-and-down direction in  FIG. 3A . 
     As shown in  FIG. 8B , in the second opened state (see  FIG. 8B ) in which the second cover  21  is opened by the second angle θ 2  (e.g., 30 degrees), the truncated part  24  is oriented in the vertical directions, or the up direction in  FIG. 8B  (see  FIGS. 6 and 7A ). In this state, when a finger or the like is nipped in the opening part  28 , the opposing force to obstruct the rotation of the second cover  21  from the second opened state to the first opened state works on the second cover  21 . In such a case, the opposing force works upward in  FIG. 8B , thereby the opposing force working such that the at least one of the shaft  22  is released from the bearing  23  as the truncated part  24  is oriented upward. 
     When the finger or the like is nipped in the opening part  28 , a downward component of the rotational force to rotate the second cover  21  is applied to the finger or the like. Then, from the finger or the like, a reactive force (i.e., opposing force) directed upward is generated. As the contacting part  27 , which is the front part of the second cover  21 , receives the reactive force, an upward opposing force works on the shafts  22 . As the upward opposing force is applied, the truncated part  24  receives a downward opposing force (see  FIG. 7B ). Since the truncated part  24  is formed to have the tapered shape, the downward opposing force also works as an inward component (i.e., leftward force in  FIG. 7B ). Accordingly, the plate spring part  26  receives the force and elastically deforms, thereby at least one of the two shafts  22  is released from the bearing  23  (see  FIG. 7B ). 
     Although one of the two shafts  22  is shown in  FIG. 7B , the other shaft  22  may be release from the bearing  23  in a similar manner. Which one, or whether one or two of the shafts  22  is to be removed depends on a position at which the finger or the like is nipped in the opening part  28  and/or amplitude of the opposing force. 
     As shown in  FIGS. 8A-8C , when the second cover  21  is attached to the cover supporting frames  9 D, the outer surfaces (i.e., the circumferential surfaces)  22 A of the shafts  22  substantially contact the inner circumferential surface of the bearing  23  except for the truncated parts  24 . With this configuration, when the second cover  21  is in the second opened state, in which the second cover  21  is opened by the second angle θ 2 , the user can detach the second cover  21 . In other state, the user can open/close the second cover  21 , and the second cover  21  will not be detached. That is, the shape of the truncated parts  24  are utilized effectively. 
     For example, when the second cover  21  is opened, when a finger is nipped in the opening part  28 , the reactive force is applied to the shafts  22 , and the truncated parts  24 . Then, because of the configuration of the truncated parts  24  formed on the shafts  22  of the second cover  21 , the shaft  22  is detached from the bearing  23 , thereby the second cover  21  being detached from the bearing  23  and the second cover  21  being detached from the cover supporting frame  9 D. With the above configuration, the damage of the second cover  21  when the second cover  21  is opened/closed can be suppressed. 
     Aspects of the present disclosures need not be limited to the above-described illustrative embodiment, and can be modified in various ways as described below. 
     In the illustrative embodiment described above, the two shafts  22  are provided to the second cover  21  and the bearings  23  are provided to the cover supporting frame  9 D. Further, the truncated parts  24  are formed on the outer circumferential surfaces  22 A of the shafts  22 , respectively. Such a configuration may be modified such that, as shown in  FIG. 9 , two shafts  22  are provided to the cover supporting frame  9 D, the bearings  23  are provided to the second cover  21 , and the truncated parts  24  may be provided in the inner circumferential surfaces  23 A of the bearings  23 , respectively. According to such a modification, when the finger or the like is nipped in the opening part  28 , because of the truncated parts  24 , the second cover  21  can be detached by the opposing force. 
     In the illustrative embodiment and modification described above, the truncated parts  24  are formed, on the outer circumferential surfaces of the shafts  22  or the inner circumferential surface of the bearing  23 , at positions corresponding to the first opened state of the second cover  21 . However, the configuration need not be limited to such ones. As shown in  FIG. 10 , the truncated parts  24  may be provided, on the outer circumferential surfaces of the shafts  22  or the inner circumferential surfaces of the bearings  23 , at positions corresponding to both the first opened state of the second cover  21  and the second opened state of the second cover  21 . In such case, by forming the truncated part  24  at a position corresponding to a position exceeding the movable range of the second cover  21 , it becomes possible to detach the second cover  21  even when the user attempts to open the second cover in excess of the movable range of the second cover  21  (e.g., in excess of the moveable range of 150 degrees). If the truncated part  24  is formed on the outer circumferential surface of the shaft  22 , when the first angle θ 1  is 150 degrees, for example, and the second angle θ 2  is 30 degrees, for example, the positions corresponding to the second opened state of the second cover  21  is, as shown in  FIG. 10 , a position apart from the position corresponding to the first opened state by the angle of θ 3  (120 degrees) rightward. 
     In the above-described embodiment and modifications, the truncated parts  24  are formed so that, when the opposing force acts in the vertical direction when the second cover  21  is in the second opened state, the second cover  21  is detached from the cover supporting frame  9 D. The aspects of the disclosures need not be limited to such a configuration, and the truncated parts  24  may be formed at directions corresponding to the direction where the opposing force may act. 
     In the above-described illustrative embodiment and modifications, a releasing part is realized by forming the truncated parts  24 . The aspects of the disclosures need not be limited to such a configuration. For example, as shown in  FIGS. 11A-11C , the releasing part may be realized by an opening  9 E formed on an upper part of the cover supporting frame  9 D, the opening  9 E, and the shaft  22  formed to be released from the cover supporting frame  9 D via the opening  9 E. 
     That is, as shown in  FIG. 11B , the shaft  22  is formed such that, when the second cover  21  is in the second opened state in which the second cover  21  is opened by the second angle θ 2  (e.g., 30 degrees), and the opposing force acts in the vertical direction (i.e., the upper direction in  FIG. 11B ), the shaft  22  is released from the opening  9 E. For example, as shown in  FIGS. 11A-11C , the shaft  22  may be formed to be a column shape of which cross section perpendicular to the rotation axis thereof has a width slightly narrower than the opening width of the opening  9 E, and both ends in a longer direction are arc-shaped having substantially the same diameter as the bearing  23 . With this configuration, in the second state, when the opposing force acts on the second cover  21 , the second cover  21  is released from the cover supporting frame  9 D.