Patent Abstract:
A device comprising a pair of lower and upper bodies respectively accommodating an image scanner and a printer. The upper body is hinged at one end thereof to the lower body so that the other end thereof is allowed to move between open and close positions. A biasing mechanism is provided for biasing the upper body not to fall down toward the second body due to the weight thereof and keep it at an arbitrary position between the open and close positions. The biasing mechanism includes a spring member and applies a first biasing force to the upper body by linearly stretching the spring member. When the upper body is in the vicinity of the lower body, the biasing mechanism further generates a second biasing force to be applied to the upper body by bending the linearly stretched spring member.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a mechanism for opening and closing a first body with respect to a second body which is pivotally connected to the first body. 
     There has been known a device that include a lower body and an upper body pivotably mounted to the lower body via a hinge such as an image forming apparatus, the upper body of which accommodates an image scanner while the lower body a printer that forms images, on a recording medium, read by the imaging scanner from an original. 
     In such an image forming apparatus, a spring member is provided for biasing the upper body to pivot upon a hinge to the open position thereof. The strength of the spring member is so adjusted that the upper body manually swung by a user to the arbitrary open position thereof does not swing back toward or fall down onto the lower body due to its own weight but remains stationary there even if a user released its hand therefrom. Thus, a user can locate the upper body at any arbitrary open position with respect to the lower body. 
     For closing, a user manually pushes down the upper body onto the lower body. At this time, the upper body tends to apply undesirable large impact onto the lower body due to the own weight thereof. Such large impact can be prevented by increasing the strength of the spring member. However, if the strength of the spring member is increased for that purpose, the biasing force thereof becomes too large for keeping the upper body stationary at a desired open position, and the upper body springs up to a fully opened position thereof each time. 
     Thus, a user has been forced to pay attention every time to softly place the upper body on the lower body, which has been considerably troublesome for a user. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an opening and closing mechanism for a hinged pair of bodies capable of smoothly and softly closing them without a user paying attention thereto. 
     According to an aspect of the invention, there is provided an opening and closing mechanism that includes first and second bodies and a biasing mechanism. The first body is pivoted to the second body so that it is movable between open and close positions with respect to the second body. The biasing mechanism biases the first body to move it toward the open position thereof. The biasing mechanism includes an resilient member and exerts a first biasing force on the first body by linearly stretching the resilient member. When the first body is in the vicinity of the second body, the biasing mechanism further exerts a second biasing force on the first body by bending the linearly stretched resilient member. 
     By the opening and closing mechanism arranged as above, a user can smoothly move the first body from the open position toward the close position and also close the mechanism softly since the biasing mechanism increases the biasing force by bending the resilient member only when the first body is in the vicinity of the second body. 
     The opening and closing mechanism further includes a link-arm member connected between the first and second bodies in such a fashion that the end of the link-arm member coupled to the second body moves relative to the second body as the first body moves. The resilient member is arranged to be linearly stretched/contracted upon movement of the link-arm member, and hence upon movement of the first body. Thus, the first biasing force generated by the spring member can be varied in accordance with the location of the first body. 
     The link-arm member is provided with an contact portion that contacts and bends the resilient member at a side thereof when the first body is in the vicinity of the second body so that the link-arm member is pushed back by the side of the resilient member and thereby biases the first body towards the open position. 
     The contact portion is, for example, a protrusion formed on the link-arm member so that the more the first body approaches the close position thereof in the vicinity of the second body, the more the bending amount of the resilient member increases. 
     In order to increase the bending amount of the resilient member, the mechanism may further include a supporting member that is arranged to contact the resilient member from the opposite side when the protrusion contacts the resilient member. 
     The link-arm member may further have a portion of U-shaped section and the contact portion may be disposed therein such that it comes in contact with the resilient member received in the U-shaped section. By such an arrangement, the resilient member is prevented from sliding off from the contact portion and the generation of the second biasing force is ensured. 
     In some cases, the mechanism is arranged such that the first body is disposed on the second body. In such a case, the strength of the resilient member may be so adjusted that the first biasing force prevents the first body from falling down towards the second body due to its own weight and keeps the first body at an arbitrary position between the open and close position thereof. 
    
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
     FIGS. 1A through 1C show perspective views of an image forming apparatus to which an embodiment of the invention is applied; 
     FIG. 2 is a perspective view of a link-arm utilized in a biasing mechanism provided to the image forming apparatus of FIG. 1; 
     FIG. 3 schematically shows an exploded perspective view of the biasing mechanism provided to the image forming apparatus of FIG. 1; and 
     FIGS. 4A through 4C schematically show the operation of the biasing mechanism shown in FIG. 3; 
     FIG. 5 schematically show an exploded perspective view of a variation of the biasing mechanism shown in FIG. 3; and 
     FIGS. 6A through 6C schematically show the operation of the biasing mechanism shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. 
     FIGS. 1A through 1C show perspective views of an image forming apparatus  1  to which an embodiment of the invention is applied, where FIG. 1A shows the image forming apparatus  1  in a fully opened state, FIG. 1B in a half opened state, and FIG. 1C in a closed state. Note that a casing of the image forming apparatus  1  is partially cut away in FIGS. 1B and 1C in order to show the mechanism inside thereof. 
     The image forming apparatus  1  have an upper body  5  and a lower body  3 . The upper body  5  accomodates an image scanner (not shown) that reads images on an original, while the lower body accommodates an inkjet printer for printing, for example, the image read by the image scanner in the upper body  5 . 
     The inkjet printer placed in the lower body  3  picks up a sheet from a sheet supplying tray (not shown) attached to the rear side of the image forming apparatus  1 . The sheet is fed through the inkjet printer, and formed an image thereon by an inkjet print head that repetitively scans across the sheet in sheet width direction. Then, the sheet is discharged from a discharge opening  13  formed at the front of the lower body  3 . 
     The image scanner provided to the upper body  5  is of a flat bed type having a platen glass (not shown) and a line image sensor (not shown) that moves along the platen glass to read the image on the original placed thereon. 
     An ADF unit  17 , or an automatic document feeder unit, is also provided at the left side of the upper body  5 . The ADF unit  17  picks up original documents from a document supply tray  21 , sheet by sheet, feeds each document over the image sensor and discharges them on a document discharge tray  19 . While the ADF unit  17  feeds the documents, the image sensor remains rest and reads the image on each document passing thereover. 
     The upper body  5  and the lower body  3  are pivotably connected to each other by means of a hinge  7  provided on the rear side of the image forming apparatus  1 . Thus, the upper body  5  can be moved up to an open position shown in FIG. 1A, by rotating about the hinge  7 , and also down to a close position shown in FIG.  1 C. When the upper body  5  is moved up, as shown in FIGS. 1A and 1B, the top of the lower body  3  becomes open and allows a user to maintain the inkjet printer placed therein, such as exchanging ink cartridges or removing jammed sheets. 
     A pair of biasing mechanisms  23  for biasing the upper body  5  towards the open position are provided between the upper body  5  and the lower body  3  near respective sides of the image forming apparatus  1 . Each biasing mechanism  23  includes an link-arm  31  connected between the upper body  5  and the lower body  3  and a spring member  41 , such as a coil spring, connected to the link-arm  31  to bias it. 
     FIG. 2 is a perspective view of the  1 ink-arm  31 . The link-arm  31  have two side plates  31   d  disposed parallel to each other, and a top plate  31   e  bridging the side plates  31   d  to form a U-shaped portion. A part of the top plate  31   e  is bent to form a protrusion  35  between the two side plates  31   d  at substantially the middle of the link-arm  31  along a longitudinal direction thereof. 
     The link-arm  31  have first and second end portions  31   f  and  31   g . The first end portion  31   f  is provided with a pair of cylindrical protrusions  31   a , each formed on the outer surface of respective side plates  31   d  to extend outwardly from the link-arm  31 . The second end portion  31   g  holds a cylindrical shaft  31   c  disposed perpendicularly to the side plates  31   d  with one end thereof penetrating one of the side plates  31   d  to protrude outwardly form the link-arm  31 . 
     An engage shaft  31   b  is further provided to the link-arm  31  between the protrusion  35  and the cylindrical shaft  31   c . The engage shaft  31   b  is located between the two side plates  31   d  with both ends thereof held by the side plates  31   d.    
     FIG. 3 schematically shows an exploded perspective view of the biasing mechanism  23  of the image forming apparatus  1 . 
     The cylindrical protrusions  31   a  formed to the first end portion  31   f  of the link-arm  31  are respectively received in a pair of bearing portion  5   a  (only one is shown) provided at the under surface of the upper body  5 . In this way, the link-arm  31  is pivotably connect with the upper body  5 . 
     The second shaft  31   c  held by the second end portion  31   g  of the link-arm  31  is slidably received, at the end thereof, in a guide groove  33  that is provided to the lower body  3 . As is best seen in FIG. 1A, the guide groove  33  is formed to a inner wall  3   a  of the lower body  3 , which extends perpendicularly from the front wall  3   b  of the lower body  3 . 
     The cylindrical shaft  31   c  of the link-arm  31  slides along the guide groove  33  as the upper body moves between the open and close positions. Therefore, the inclination of the link-arm  31  with respect to a top surface of the lower body  3  changes as the upper body  5  moves. 
     The spring member  41  is connected between the lower body  3  and the link-arm  31  by hanging one of the hooks formed at each end thereof to the engage shaft  31   b  of the link-arm  31  and the other one to an engaging portion  39  formed to the lower body  3 . The length of the spring member  41  is adjusted such that the spring member  41  is linearly stretched by the link-arm  31  irrespective the position of the link-arm  31 . Accordingly, the link-arm  31  is always pulled by the spring member  41  so that it biases the upper body  5  towards the open position. 
     A supporting member  43  is provided below the spring member  41 . The supporting member  43  contacts the spring member  41  from the underside as will be described later. 
     FIGS. 4A through 4C schematically show the operation of the biasing mechanism  23 , where FIGS. 4A and 4C respectively show the biasing mechanism  23  with the upper body  5  at the open and close positions, while FIG. 4B shows the biasing mechanism  23  with the upper body  5  located between the open and close positions. Note that, the left and right sides of each of FIGS. 4A through 4C corresponds, respectively, to the rear and front sides of the image forming apparatus  1 . 
     When the upper body  5  is located at the open position, the cylindrical shaft  31   c  of the link-arm  31  is located at the most rear side of the guide groove  33 , as shown in FIG.  4 A. In this state, the spring member  41  is slightly stretched by the link-arm  31 . The biasing force applied to the upper body  5  from the biasing mechanism  23  is small but enough for preventing the upper body  5  from moving towards the close position due to its one weight. 
     As the upper body  5  moves down towards the close position, the link-arm  31  pivots about the cylindrical protrusions  31   a  received in the bearing portion  5   a  in a counter-clockwise direction in FIG. 4A, and the cylindrical shaft  31   c  moves along the guide groove  33  towards the front side thereof (see also FIG.  4 B). The movement of the cylindrical shaft  31   c , or the link-arm  31 , gradually stretches the spring member  41  and thereby increases the biasing force of the biasing mechanism  23 . 
     The guide groove  33  is formed in a slightly curved shape to control the increase of the stretched amount of the spring member  41  and hence the biasing force applied to the upper body  5 . The guide groove  33  is formed such that the rotation moment of the upper body  5  about the hinge  7  caused by the weight thereof is canceled by the biasing force of the biasing mechanism  23  irrespective the location of the upper body  5 . Accordingly, the upper body  5  remains stationary at any arbitrary position between the open and close positions thereof. 
     As the upper body  5  is further moved down towards the close position and comes to the vicinity of the lower body  3 , as shown in FIG. 4B, the protrusion  35  of the link-arm  31  contacts the spring member  41  at a side thereof. If the upper body  5  is further moved towards the lower body  3 , the protrusion  35  presses down the spring member  41 . As a result, the spring member  41 , already linearly expanded by the link-arm  31 , bends as shown in FIG.  4 C. 
     Note that the protrusion  35  contacts the spring member  41  between the two side plates  31   d  of the link-arm  31 . The side plates  31   d  restricts the lateral movement of the spring member  41  and prevent it from sliding off from the protrusion  35 . 
     The supporting member  43  also contacts the spring member  41  when the protrusion  35  bends the spring member  41 . The supporting member  43  contacts the spring member  41  from the underside thereof to increase the bending amount of the spring member  41 . 
     The bent spring member  41  pushes back the protrusion  35 , and hence the link-arm  31 , and thereby significantly increases the biasing force applied to the upper body  5  from the biasing mechanism  23 . This large biasing force prevents the upper body  5  from hardly bumping against the lower body  3  and applying large impact thereto at the moment of closing it. 
     FIG. 5 schematically shows an exploded perspective view of an biasing mechanism  123  which is a variation of the biasing mechanism  23  shown in FIG.  3 . The biasing mechanism  123  shown in FIG. 5 differs from the mechanism  23  shown in FIG. 3 in that the spring member  41  is replaced by an elongated rubber member  141  such as a rubber tube. In other points, the biasing mechanism  123  shown in FIG. 5 is arranged same as that shown in FIG.  3 . 
     The elongated rubber member  142  has a first through hole  142   a  formed at one end portion thereof for engagement with the engaging portion  39  of the lower body  3 , and a second through hole  142   b  formed at the other end portion thereof for engagement with the engaging shaft  31   b  of the link-arm  31 . 
     FIGS. 6A through 6C schematically show the operation of the biasing mechanism  123  shown in FIG.  5 . The biasing mechanism  123  shown in FIG. 5 works in the same manner as that of the biasing mechanism  23  shown in FIG.  3 . That is, as the cylindrical shaft  31   c  is at the most rear side of the guide groove  33 , as shown in FIG. 6A, the elongated rubber member  141  is in a slightly expanded condition so that the biasing mechanism  123  exerts a biasing force small but enough for preventing the upper body  5  from moving towards the close position. The elongated rubber member  141  is gradually stretched as the cylindrical shaft  31   c  moves along the guide groove  33 , as shown in FIG. 6B, to increase the biasing force of the biasing mechanism  123 . The strength of the elongated rubber member  141  is adjusted such that biasing mechanism  123  can hold the upper body  5  stationary at any arbitrary position between the open and close positions thereof. 
     As the cylindrical shaft  31   c  moves further along the guide groove  33 , the elongated rubber member  141  is bent by the protrusion  35  of the link-arm  31 , which presses down the side of the elongated rubber member  141 , and the supporting member  43 , which contacts the elongated rubber member from the opposite side (see FIG.  6 C). The elongated rubber member  141  bent as above pushes back the link-arm  31  so that the link-arm  31  biases the upper body  5  with a greater force than before towards the open position. As a result, the biasing mechanism  123  prevents the upper body  5  from applying large impact to the lower body  3  at the moment of closing it. 
     It should be noted that both the spring member  41  shown in FIG.  3  and the elongated rubber member  141  shown in FIG. 5 may be replaced by any suitable resilient member that has engaging portions at both end portions thereof and generates an opposing force when a force is exerted thereto to increase the distance between the two engaging portions. 
     Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiment and those variations would be within the spirit and scope of the present invention. For example, in some cases, the link-arm of the biasing mechanism may be connected slidably with the upper body and pivotably with the lower body, and the spring may be connected between the upper body and the link-arm. In other cases, the upper and lower bodies may accommodate devices other than the image scanner and the inkjet printer, or may even accommodate no devices. 
     The present disclosure relates to the subject matter contained in Japanese Patent Application No. P2001-298274, filed on Sep. 27, 2001, which is expressly incorporated herein by reference in its entirety.

Technology Classification (CPC): 8