Abstract:
A hinge apparatus employs a base, a second base, link arms, urging means and the characteristics of a parallelogram formed by the shape of said base, second base and paired link members to enable a body such as a platen cover to rotate up open and lower substantially parallel to an original platen and to enable the parallel opening of the body thereby ensuring the complete covering of a thick original or a book original placed upon the clear glass platen enabling good quality copies of the original regardless of its thickness.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pivotably opening and closing hinge apparatus that connects two devices and particularly to a hinge apparatus that supports an opening and closing automatic document feeder equipped over the original platen or the cover placed on the original platen established on the upper surface of a photographic copying machine; a facsimile apparatus or an image scanner (called image forming apparatus below). 
     2. Description of the Related Arts 
     Image forming apparatuses have a clear glass platen plate (called platen below) that comprises the original platen through which light is radiated from below to reflect off of an original document so that the reflected image can be obtained to form an image of the original placed on that platen. It is not unusual for an operator to place one sheet of an original or to place a thick book on the platen for photocopied reproduction. In either case, it is essential to the clarity and the quality of the reproduction of the original to prevent the excessive diffusion of light outside of the image forming apparatus by using a covering body or a cover to push and press the original securely against the platen. 
     Ordinarily, platen covers are attached to the upper part of the image forming apparatus using a hinge. Ordinary hinge mechanisms have a first attachment plate that is firmly attached to the image forming apparatus and a second attachment plate that is firmly attached to the platen cover that pivot around a common rotating axis. In this construction, the platen cover pivots around this axis to allow the platen cover to open and close with respect to the top of the platen. 
     It is not uncommon that the platen cover also has functions that are often associated with an automatic document feeder wherein such an apparatus is mounted onto the image forming apparatus to enable the consecutive feeding of a plurality of unbound and loose sheets one sheet at a time to the platen of the image forming apparatus. In such a case, the automatic document feeder itself also performs the essential function of the platen cover. 
     It should be understood that when an operator wants to use an image forming apparatus to copy specific pages from a relatively thick medium such as a book, the ordinary hinge mechanism just described, namely of a cover or an automatic document feeder mounted onto an image forming apparatus, can only apply a pushing pressure to one edge of the thick original, or book, to hold it in place against the platen of the image forming apparatus which will damage the binding of a book. Of course, if the operator should apply too much pressure from above onto the cover or the automatic document feeder to more completely cover the medium and thereby attempt to prevent unwanted diffusion of light, there would be an unequal distribution of pressure on the platen which will result in the damaging or even the cracking of the platen. 
     Thus, in order to alleviate such unwanted situations that result from the two piece construction of an automatic document feeder mounted to an image forming apparatus, it is desirable to arrange the structure of one device (hereinafter called “platen cover”) with respect to the other device so that it can apply an equal pressure over the entire back side of a thick book by being parallel with respect to platen. 
     There have been opening and closing hinge apparatuses that move the platen cover into a vertical and parallel position above the platen. 
     An example of the prior art is disclosed in Japanese Patent Application Disclosure No. Hei 5-9597. The hinge apparatus (hereinafter called “first art”) described is shown in FIGS. 15A to  15 D. The first art shown in FIG. 15A comprises the attachment frame  302  which is attached to the copy machine  301  and the movable hinge  304  which is attached to the platen cover  303 . The rising and lowering hinge  306  pivotably supports the movable hinge  304  on the shaft  305  and the parallel link arms  307  and  308  are connected to allow the rising and lower hinge  306  to move vertically with respect to the attachment frame  302 . One end of each of the parallel link arms  307  and  308  is attached to the attachment frame  302  by shafts  309  and  310  respectively, and the other ends of each of the parallel link arms  307  and  308  are attached to the rising and lowering hinge  306  by the shafts  311  and  312 , respectively. As can be seen in FIGS.  15 (A) through (D), when the platen cover is opened by operating the platen cover hinge  303  to copy a thick document  313 , the inner side of the platen cover pushes on the outer edge of the thick document  313  as the operator opens the platen cover by lifting. This pivots the platen cover on and around the line of the point of contact by pushing on the edge of the thick document  313 . In the system as described for the hinge mechanism related to the first art, the rising and lowering hinge  306  is attached to the frame  302  using the parallel links  307  and  308  so the vertical movements of the parallel links  307  and  308  have substantially the same circular action. Thus, it is possible to attain the smooth upward movement of the rising and lowering hinge  306  only if the rotational force of the platen cover  303  is transmitted to the rising and lower hinge  306  using the thick document  313 . 
     This hinge structure unifies the lifter mechanism by connecting the rising and lowering hinge  306  to the attachment frame  302  with the parallel links  307  and  308  thereby making it possible to provide a single hinge apparatus which encompasses both the opening and closing functions and the lifter function. 
     Another hinge apparatus (called “second art” below) is disclosed in Japanese Patent Application No. Hei 61-20587 disclosed in the prior art as a document holder capable of opening and closing. This hinge apparatus, as can be seen in FIG. 16, comprises the lifter  351  which is attached to the copy machine  350  and the hinge  352  which is attached to the lifter  351 . The platen cover  353  can be opened and closed with the hinge  352 . The lifter  351  is composed of the base plate  354  and the paired first rising and lowering arms  355  and  356  which are attached to base plate  354  so that the platen cover  353  is vertically movable in the direction of opening and closing. The paired second rising and lowering arms  357  and  358  are movably attached to the free end of both the paired first rising and lowering arms  355  and  356  and the bracket  359  is attached to the free ends of the paired second rising and lowering arms  357  and  358 . This bracket  359  employs the attached structure of the hinge  352 . It is possible with this particular structure for an operator to place a thick book onto the platen without the front end of the platen cover remaining at an angle. This structure allows the complete and parallel covering of the upper surface of the book. It is also important to note that the structure of this apparatus prevents the platen cover from bending and it prevents the diffusion of light to outside of the photographic copy machine and the infusion of light into the internal optical system. 
     However, in the hinge apparatus of the first art just described, the pressing action of the platen cover  303  causes the lift mechanism to continue functioning while the edge of the book and the platen cover  303  are in contact. Thus, the thickness and the positioning of the book on the platen induce the book to move and become displaced in the left and right directions of FIG.  15 C. Such a force generated by this movement presents the unwanted possibility of bending or otherwise damaging the pages that are in contact with the platen or causing the book to become mis-positioned. In this hinge apparatus, there is no systematic relationship between the movements of the hinge  306  and the lift action so when the operator is opening or closing the platen cover  360 , he or she must perform the separate and unrelated actions of opening or closing the platen cover  360  and then operating the lift. These make the operation of the platen cover  360  a more complex task when the copying of a thick book is desired. 
     Also, in the platen cover hinge apparatus described above as the second art, there is an excessive cost because of the duplicative construction of each of the parts which are independently structured to enable the lift mechanism which uses a jack method to raise and lower the hinge for the opening and the closing actions. Also, because the operator must perform the action of opening or closing the platen cover and the action of lifting the entire platen cover, as is also the case with the first art, the operation of the platen cover is a more complex task and therefore it is more difficult. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a hinge apparatus that can perform both the rotating function along with a rising and lowering action to allow the platen cover to cover the thick book original both horizontally and parallelly without damaging the book or causing mis-positioning of the book. 
     It is also an object of the present invention to provide a hinge apparatus that is capable of pivoting open, and that is also capable of rising and lowering parallel to the copy machine body in one easy operation. 
     Another object of the present invention is to provide a hinge apparatus which is of a simple construction and which enables a platen cover to pivotally rotating open and to rise and lower parallel to the copy machine body in one easy operation. 
     In order to attain the objectives of the hinge apparatus, the present hinge apparatus that connects two bodies and opens and closes comprises an arm member pivotably attached to one of either of two bodies and an arm member connected to the other of the bodies. The first and second paired link members are equally spaced from each other and the bases of the arm members are pivotably attached to the apparatus body. The paired link members pivot in the same direction on their ends spaced apart in the direction of the pivot. 
     Also, the distances of the paired link members in the pivoting direction and the lengths of the link members substantially form a parallelogram. 
     There is also a means for restricting the opening and closing movement of at least one side of the pivoting movement of said arm member and the pivoting movement of said link arm member. 
     At the point where the platen cover is rotating from an open state to a closed state, a restricting means restricts the movement so that the first arm member will rotate, then the link member will rotate. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective side view of the hinge apparatus of the present invention. 
     FIG. 1B is a perspective side view of an automatic document feeder. 
     FIGS. 2A,  2 B and  2 C are perspective side views of the hinge apparatus showing the transition of the platen cover rising. 
     FIGS. 3A,  3 B and  3 C are perspective side views of the hinge apparatus of the present invention showing the transition of the movement of the hinge apparatus on the platen cover. 
     FIGS. 4A,  4 B and  4 C are perspective side views of the hinge apparatus of the present invention showing the transition when raising the hinge apparatus parallel to the platen cover. 
     FIG. 5 is a partially sectional side view of the hinge apparatus  101  of the present invention showing the determined sequential movements relating mutually to the rising action of the hinge apparatus by the lock arm mechanism. 
     FIGS. 6A,  6 B and  6 C are perspective side views of the hinge apparatus  101  showing the transition when opening the hinge apparatus from a closed state on the platen cover. 
     FIGS. 7A,  7 B and  7 C are perspective side views of the hinge apparatus  101  showing the transition continuing from FIG. 6A, FIG.  6 B and FIG. 6C of the platen cover closing after opening to a maximum. 
     FIGS. 8A,  8 B and  8 C are perspective side views of the hinge apparatus  101  showing the transition continuing from FIGS. 7A,  7 B and  7 C of the platen cover closing further and returning to its original status. 
     FIG. 9 is a perspective side view of the hinge apparatus showing the use of two springs in place of the spring  8  in the hinge  1  shown in FIG.  1 . 
     FIG. 10 is a side view of the hinge apparatus  201 . 
     FIG. 11 is a plan view of the hinge apparatus  201 . 
     FIG. 12 is a partially sectional view of the hinge apparatus  201 . 
     FIG. 13 is a partially sectional view of the hinge apparatus  201 . 
     FIGS. 14A,  14 B and  14 C are a side views of the hinge apparatus  201 . 
     FIGS. 15A,  15 B,  15 C and  15 D show the first prior art hinge apparatus. 
     FIGS. 16A and 16B show the second prior art hinge apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a detailed explanation of the preferred embodiments of the present hinge apparatus based on the figures provided. 
     FIG.  1 (A) is a perspective view of the hinge apparatus  1  for the opening and the closing of the platen cover B of an automatic document feeder device or the like that is attached to the upper part of an image forming device A such as a copying machine or image reading device. The dotted lines of the drawing indicate the areas that are concealed from view inside of the apparatus. The hinge apparatus  1  is permanently attached to the top of the device A and it has a base  7  that also acts as a supporting member. The upper side of the hinge apparatus  1  has the second base  9  that is the member that is permanently attached to the platen cover B (called cover B below) which is the cover for the image forming device A. The cover B is attached extending in the length direction of the second base  9 . Therefore, as is explained in our detailed description of the preferred embodiments provided below, it is easy for an operator to set a document or other original onto the top of the platen glass C (called platen below) that is established on the upper surface of the image forming device A or to vertically raise and lower the platen cover directly over the thick book to apply an equalized pressure from above because of the rotating movement and the up and down movement of the second base  9 . 
     One end of the arm  4  is pivotably supported by pin  18  so that the arm  4  can rotate around the center of the pin  18 . The arm  4  is also connected to the base  7  by the pin  18 . The arm  4  and second base  9  are connected by the forward link  2  and rearward link  3  that are established at a determined distance at the front and back sides with respect to the opening and closing direction. At the other end of the arm  4 , forward link  2  is pivotably supported by pin  14  so that the forward link  2  can rotate around the center of the pin  14  and one end of the forward link  2  is pivotably connected to the arm  4  by the pin  14 . Also, at a mid-point position of the arm  4  and established at a distance in the front and back sides of the opening and closing direction, the rearward link  3  is pivotably supported by pin  15  so that the rearward link  3  can rotate around the center of the pin  15  and rearward link  3  is connected to the arm  4  by the pin  15 . In a position near the pin  18 , the pin  17  is attached to the base  7  and at a position slightly separated from the pin  14 , the pin  19  is attached to the forward link  2 . An urging means, for example a compressed spring  8  adjoins the two pins of  17  and  19 . At the upper end of the forward link  2 , the second base  9  is pivotably supported by the pin  12  so that both the second base  9  and the forward link  2  can rotate relative to each other around the center of the pin  12 . The forward link  2  is connected to the second base  9  by the pin  12 . At the upper end of the rearward link  3  and substantially parallel to the forward link  2 , the second base  9  is pivotably supported by the pin  13  so that both the second base  9  and the rearward link  3  can rotate relative to each other around the center of the pin  13  and the rearward link  3  is connected to the second base  9  by the pin  13 . An imaginary line connecting the central points of each pin from pin  14 , the pin  15 , the pin  13  and the pin  12  from the pin  12  forms a four sided shape that is substantially a parallelogram. The forward link  2  and rearward link  3  change the shape of that parallelogram by rotating around the center of each of their respective pins namely pin  14  and pin  15 . Also, when the cover B is opened, the compressed spring  8  widens the parallelogram and the second base  9  rises parallelly. When narrowed, the second base  9  lowers compresses the spring  8 . Therefore, it is possible to adjust the rising and lowering movements of the platen cover B by changing the shape of the parallelogram. Because the widening of the parallelogram is restricted by the clockwise rotation of the forward link arm  2 , the second base  9  will not move to a position that is higher. The platen cover B also opens and closes by the rotation of the second base  9  in relation to the rotation of arm  4 . Therefore, arm  4  functions as the rotation member for the opening and closing of the cover B. The distance of the vertical movements of the second base  9  depends on how wide the edges of the parallelogram are separated. Consequently, the thickness of the original documents which can be pressed and held in place by the cover B depends on how wide the edges of the parallelogram open. This, therefore, requires that the distance of the space between the forward link  2  and the rearward link  3  correspond to the thickness of the document which is to be copied. 
     The following provides a detailed description of the hinge apparatus  1  using FIG. 2, FIG.  3  and FIG.  4 . As is shown in FIGS. 2A,  2 B and  2 C, the process of the forward link  2  and the rearward link  3  rotating relative to the arm  4  to enable the parallel movement of the second base  9  and concequently the cover B from a closed and un-rotated state. Through this, it is possible to raise and to keep the cover B parallel to the platen C surface on the upper portion of the device A. In FIG. 3, the forward link  2  and the rearward link  3  are not rotating, in other words, the second base  9  and the arm  4  do not change the positions relative to each other. Rather, only the arm  4  rotates around the center of the hinge  18  to move the cover B from a closed state to an open state (which is the hinging action). FIG. 4 shows a combination of the actions performed in FIG. 2 of the rotation of the forward link  2  and the rearward link  3  and in FIG. 3 of the rotation of the arm  4  to show the process of the up and down actions and the opening and closing rotations of the second base  9 . In this way, the hinge apparatus  1  as described in FIG. 1 can be independently and simultaneously raised and lowered in parallel to the original platen and can perform the hinging action of the cover B. Therefore, it is possible to ensure that the up and down position of the cover B corresponds to the thickness of the book, when closing the cover B onto a thick book which has been placed on the platen surface on the upper part of an image forming apparatus. Also, this mechanism which employs the parallel and up and down movements of the arms  2  and  3  on the arm  4  to allow this hinging action, the cover B can be closed under the same status in which it is open, thus making it easy to lower the cover in a direction that is parallel to the platen surface thus leaving the original undamaged. 
     If the cover B also performs the function of being an automatic document feeder to automatically and sequentially transport documents over the platen C, that automatic document feeder device would be structured like the apparatus shown in FIG.  1 (B). 
     To provide an explanation of how such an apparatus should function, the automatic document feeder would include the sheet separator means  52  to take one sheet at a time from a plurality of sheets stacked on the feed stacker  51  and sequentially transport them to the platen C for processing. At this point, the transport means  53  transports the document to abutment with the stopper  54  established on the image forming device to be set on the copy machine. After the copying process is completed on this device, the stoppers  54  retracts to allow the transport means  53  to drive the sheet through the discard means  56  to stop the sheet at the discard stacker  55 . 
     The hinge apparatus  1  as described in FIG. 1 allows the independent vertical movement of the hinge action of the cover B, as explained using FIG. 2, FIG.  3  and FIG.  4 . FIG. 5 shows that it is possible for the hinge apparatus  101  to combine the hinging action and the up and down action of the second base  9  to open and close and raise and lower the cover B through a determined sequence by restricting the up and down movement according to the status of the hinging action. 
     Here, we refer to the perspective view of the hinge apparatus  1  of FIG. 5 to explain the differences from the hinge apparatus of FIG. 1, namely that the lock arm  105  which provides a part of the movement control means. The pin  116  and the spring  131  have been newly added to the structure of the hinge apparatus of FIG.  1 . The shapes of the forward link  2 , the arm  4 , the base  7  and the second base  9  have been changed and each of the forward link  102 , the arm  104 , the base  107  and the second base  9  have been placed in different locations. 
     Base  107  is connected to one end of the arm  104  by pin  18  that pivotably supports the arm  104 , in the same way as was explained in reference to to FIG.  1 . The arm  104  has an elongated slide aperture  124  established in a part of the arm  4  of FIG. 1 and a ridge to limit the clockwise directional rotation of the forward link arm  102 . Also, forward link  102  has the cam  102   a  protruding on one side of the area around arm  104 . This cam mechanism moves by the rotation of the cam  102   a  by corresponding to the rotation of the forward link  102  around the pin  14 . The stopper  102   c  is provided on the forward link  102  to support one end of the spring  131  wound around pin  12 . The lock arm  105  has a slightly elongated slide aperture  123  into which one end of the hole pin  17  is inserted. The pin  17  is supported by the base  107 . The pin  116  supports the other end of the lock arm  105  and is inserted into the slide aperture  124  of the arm  104 . Therefore, the lock arm  105  has suitable room to move slightly along the slide aperture  123 . The slide aperture  124  and the lock arm  105  rotates around the centers of the pin  17  and the pin  116  according to the rotation of the arm  104 . The substantially straight sided cam section  102   b  is formed on the cam  102   a  of the forward link  102 . The pin  116  is in constant contact with the straight sided cam section  102   b  on the cam  102   a  to limit the rotation of the forward link  102  in the counterclockwise direction. The attachment position of the slide unit member  109   c  established at the opening  109   a  and screw attachment unit  109   b  is variable by the screw  109   d  in the second base  109 . Therefore, the speed of the cover B that rotates around the center of the pin  12  is slowed in the closing direction because the end of the spring  131  is pressed against the slide unit member  109   c . It is possible to change the speed of the cover B in the closing direction by changing the position of the slide unit member  109   c  by turning the screw  109   d . Because other explanations of this hinge apparatus continue to be the same as those described in our reference to FIG. 1, they shall be omitted. 
     Following is an explanation of FIG. 6 to FIG. 8 which show, in order, the progression of the hinge apparatus  101  from the closed state of cover B that is attached to the second base  109 , or in other words, from the un-inclined and horizontal state of the second base  109  to the cover B opening and further to the opened state and back again to the original closed state of cover B. Here, it is clear that the lock arm  105  and the cam  102   a  on the forward link  102  adjust the distance of the forward link  102  and rearward link  3  according to the rotating position and rotating direction of the arm  104  to allow the rising and lowering and the hinging action of the cover B in one fixed sequence. 
     Here, we will explain in detail the effects of the mechanisms and the sequences in their order beginning from FIG.  6 . FIG.  6 (A) shows the closed state of the cover B. Furthermore, FIG.  6 (A) shows the hinge apparatus  101  substantially touching and pressing the cover B against the platen C with either no document on the platen C or a very thin sheet document on the platen C. In this situation, arm  104  is laying substantially in a horizontal direction. Cam  102   a  is rotated to its maximum in the counterclockwise direction and the substantially straight sided cam section  102   b  pushes the pin  116  into the right direction of the FIG. Therefore, the angles formed by the axes of the pin  18  and the pin  14  and the pin  14  and the pin  12  are at their minimum. This is where the forward link  102  and the rearward link  3  are in their closest proximity and the second base  109  is precisely at its lowest point. The pin  116  is also slid into the right direction of the FIG along the slide aperture formed by the slide aperture  124 . On one end of the lock arm  105  is established the slide opening  123  which controls the movement of the lock arm  105  through the contact of the pin  17 . This, then, forces the lock arm  105  to its furthermost right position. 
     The force generated when the operator opens the cover B, transmits the moment to the arm  104  to cause the rotation of the arm  104  in the counterclockwise direction, as shown in FIG.  6 (B) and FIG.  6 (C). Following that rotation, the lock arm  105  rotates in the same way centering around pin  17  in the counterclockwise direction. The forward link  102  receives the moment of the counterclockwise rotation centered around the pin  14  by the force of opening the cover B which causes the straight sided cam section  102   b  to push the pin  116  on the lock arm  105  toward the opposite position of the pin  117 . The lock arm  105  then rotates toward the opposite direction in this angled state. Because the pin  17 , which is the axis of rotation of the lock arm  105 , is established at a position separated from the pin  18  which is the axis for the rotation of the arm  104 , the position of the pin  116  rotates to the right while moving to the left relative to the pin  14  following the counterclockwise directional rotation of the arm  104 . The pin  14  and pin  116  follow the same arc. Therefore, the pin  116  moves in a direction relative to the pin  18  along the slide aperture  124  while remaining in contact with straight sided cam section  102   b . Because the straight sided cam section  102   b  of cam  102   a  is thus pushed from the slide aperture  124  cam  102   a  rotates in the clockwise direction centering around the pin  14 . The result is that the forward link  102  rotates in the clockwise direction of the pin  14  with the opening of the cover B. Therefore, the second base  109  is capable of moving parallelly to the platen in the vertical direction and the cover B rises as the angles of the parallelogram as formed by the points of the centers of each of the pins of the pin  12  to the pin  14 , the pin  15 , the pin  13  and the pin  12  again, increase. In this way, in response to the angle of the opening of the cover B, the cover B hinge action and rising action are brought into a meaningful relationship because the position of the pin  116  differs with respect to the arm  104  and the forward link  102 . Also, as shown in FIG.  6 (C), when the arm  104  rotation angle is reached, the straight sided cam section  102   b  of the cam  102   a  is substantially parallel on the elongated direction of the slide aperture  124 . Rotating the arm  104  any further almost completely ceases the movement of the enlarging of that parallelogram. Because the one side  104   a  of the arm  104  pushes at a constant against the forward link  102   a  in the clockwise direction, the second base  109  does not move parallel to the upward direction any further. Therefore, as shown from FIG.  6 (A) to FIG.  6 (C), the rotational movement and the rising movement occur simultaneously when the cover B is opened. 
     FIGS.  7 (A) to (C) show the process of closing the cover B from after it has been opened. FIG.  7 (A) shows the cover B opened further to its maximum limit from FIG.  6 (C). Arm  104  moves all the way to the left rotation (also called counterclockwise rotation) and along with that movement the pin  116  attached to the lock arm  105  moves to its furthest in the direction relative to pin  18  along the slide aperture  124 . However, because the straight sided cam section  102   b  is substantially parallel with the slide aperture  124 , there is less outward push by the pin  116  at the slide aperture  124  of cam  102   a . Therefore, in the processes from FIG.  6 (C) to FIG.  7 (A), there is almost no change in the position of the second base  109  relative to the arm  104  and the rise is substantially stopped only by opening the cover B. When the cover B is later closed from an open state, the lock arm  105  lowers in the direction of the base  107  under its own weight as shown in FIGS.  7 (B) and (C) and the pin  116  moves only slightly in the direction of pin  17 . If the lock arm  105  does not lower under its own weight, the force of pressing the cover B causes a moment to occur in the clockwise rotation direction on the forward link  102  and pin  116  receives that force in the downward direction from the straight sided cam  102   b . The lock arm  105   a  lowers, then, in the same way toward the base  107 . 
     FIG.  8 (A) and FIG.  8 (B) show the cover B in a closed state in FIG.  7 (C) and the end state in which the cover B is parallel with the platen C. Here, the lock arm  105 , as explained while referring to FIGS.  7 (B) and (C), is positioned slightly away from the pin  18  direction. The effect to the position of the second base  109  by the slight difference in positioning is increased as the arm  104  moves toward its original position. Therefore, the return rotation action of the cam  102   a  on the forward link  102  is restricted by the pin  116  displaced in the direction of the pin  17 , and the forward link  102  and the rearward link  3  are opened and parallel. The result is that the cover B is held in a state that is a parallel distance with regard to the platen C. 
     Also, supplying a downward force to the cover B causes that force to be applied to the forward link  102  and the rearward link  103  at the moment of the counterclockwise rotation centered around the pin  14  and the pin  15 . Because of that moment, the straight sided cam section  102   b  applies a force that moves the pin  116  in the opposite direction to that of the pin  17  along the slide aperture  124  thereby moving the lock arm  105 . The movement of the lock arm  105  and the pin  116  rotate the cam  102   a  further in the counterclockwise direction and the rearward link  103  and the forward link  102  rotate around the pin  14  and pin  15 . Therefore, the second base  109  and the cover B which is therein attached lower downward and parallel in order. If a thick document has been set on the platen C, the lowering is limited at the position contacting the upper surface of such document and the lower surface of the cover B pushes parallelly to the upper surface of that thick document. 
     As explained above, the differences in the opening and closing angle and the opening and closing directions of the cover B cause differing positions of the pin  116  with regard to the arm  104  and forward link  102 . There is a then a causal relationship between the rising and the opening rotation of the cover B because of the series of predetermined sequences in that action. Also, when the cover B is changed from a closed state to an opened state, it moves parallel along with a rotating movement and when the cover B is changed from the opened state to the closed state it rotates until the cover B has a uniform and parallel distance from the platen C and lowers while maintaining that parallelism. 
     Continuing along with our explanation of the present invention, we will explain the compression spring  8  which is established within the above described apparatus. Referring now to FIG.  1  and FIG. 5, one end of the spring  8  is attached to the pin  17  on the base  7  and the other end of the spring  8  is attached to the pin  19  which is connected to the forward arm  2 . We will consider, here, that the hinge apparatus  1  and the base  7  of  101  are attached to the copy forming device A and that the cover B is attached to the second base  9  and  109 . The cover B extends in the length direction in FIG. 1 from the second base  9  and  109 . Also, the weight of the cover B supplies the moment of force in the clockwise rotational direction with regard to the arm  4  and  104 . Also, because the center of gravity of the cover B is at the position away from the second base  9 , there is a difference in the moment exerted to arm  4  and  104  by the situation of the opening and closing of the cover B. For example, in order to make the cover B parallel with the platen C, the arm  4  and  104  must be substantially horizontal which is where there is the greatest rotational moment applied to the arm  4  and  104 . Conversely, when the cover B is opened in the vertical direction, arm  4  and  104  receive the weakest rotational moment. Therefore, the spring  8  is employed to enable a resilient opposing force to resist the rotational moments that vary according to the status of the opening and closing of the cover B. Also, in the hinge apparatus  1  as described for FIG. 1, a resilient member is used to resist the forward link  2  and rearward link  3  rotational moments in the counterclockwise direction centering around the pin  14  and the pin  15  caused by the weight of the cover B. Also, if the degree of compression of the spring  8  is great, any compressing means whose repelling force is accordingly great, such as a cylinder in which compressed air is sealed can be used. It is also possible to set that pressing force in accordance with the weight of the cover B. 
     Next, we will refer to FIGS. 2 through 4 and FIGS. 6 through 8 to describe the action of the spring  8 . With regard to the up and down movements of the second base  9  as shown in FIG. 2, the cover B is attached to the second base  9  so that the weight of the cover B is placed upon the second base  9 . The weight on the second base  9  operates as the moment of force to rotate in the counterclockwise direction centering around the pin  14  and the pin  15  with regard to the forward link  2  and the rearward link  3 . Therefore, the spring  8  is established between the base  7  and the forward link  2  to resist that moment and support the weight of the cover B to allow the up and down movements of the cover B with little resistance felt by the user. 
     One end of the forward link  2  side of the spring  8  is separated from the pin  12  and it is attached to the pin  19  which is attached near the pin  14 . It is possible with this structure to supply a substantially uniform pushing force to the pin  19  with regard to the cover B weight without any variation in the expanding or contracting of the spring  8  even if the forward link  2  is rotated to raise or lower the cover B. Therefore, by rotating the forward link  2 , the variation in the spring  8  affects the arm  4  rotating movement only slightly. 
     The rotational moment weakens in the order shown from FIG.  3 (A) to FIG.  3 (B) to FIG.  3 (C) with regard to the opening and closing movement of the second base  9  in FIG.  3 . Therefore, in resistance to the rotational moment, and to prevent the cover B from closing easily, the force of resistance must be reduced. Because the spring  8 , as described previously, utilizes the expanding force that is generated with relation to the degree of compression, the repelling force is greater if the compression is greater. Therefore, the spring  8  is attached between the base  7  and  107  and the forward link  2  and  102  so that the repelling force is at its greatest when the cover B is in the states shown in FIG.  3 (A) and FIG.  6 (A) and the repelling force is at its weakest when the cover B is in the states shown in FIG.  3 (C) and FIG.  7 (A). For example, in FIG.  1  and FIG. 5, one end of the base  7  side of the spring  8  is separated from the pin  18  and it is attached to the pin  17  established lower than a straight lining formed between the pin  18  and the pin  14 . The compression of the spring  8  is greatest and the repelling force is greatest when the cover B is closed and when the arm  4  and  104  are horizontal as can be seen in FIG.  3 . Conversely, the spring expands thereby decreasing its repelling force when the cover B is rotated in the direction of opening the cover B. At this point, there is a separation between the pin  17  and the pin  19  by the opening. When the cover has opened to its maximum state, as is illustrated by FIG.  3 (C), the repelling force is at its weakest. 
     Thus, it is possible to receive both the moment of rotation of pin  14  caused by the weight of the cover B which moves up and down and open and closed and the moment of rotation of pin  18  by establishing one spring  8  between the base  7  and  107  and the forward link  2  and  102  for the hinge apparatus  1  and hinge apparatus  101 . Also, because in the hinge apparatus  101  shown in FIG. 5, the pin  116  on the lock arm  105  moves inside the slide aperture  124  by the rotational movement of arm  104  centered around pin  18  in the sequences of movement as shown in FIG.  6 (A) through FIG.  8 (C). With the change in the size of the parallelogram formed by the forward link  102  and rearward link  3 , the cover B moves up and down and there is a decrease in the weight placed on the spring  8  by the rotational moment of the pin  14 . Thus, there is less resilience and while it is possible to use a small spring, it is possible to improve the opening and closing operation of the cover B by reducing the load on the cover B. 
     In place of the spring  8  for the hinge apparatus  1  in FIG. 1, we will explain using  2  new springs  30  and  31 . FIG. 9 shows the construction of the pin  17  pivotably supported on the base  7 , the pin  32  pivotably supported on the arm  4  between which is attached the spring  30  and between the pin  32  and the pin  33  pivotably supported by the forward link  2  is attached the spring  31 . Both the spring  30  and  31  have the repelling force to push in the outward direction. Therefore, the spring  30  causes the moment to rotate the arm  4  in the counterclockwise direction from the position in the drawings centered around the pin  18  and the spring  31  causes a moment to rotate the forward link  2  in the clockwise direction centered around the pin  14 . The repelling force of the spring  30  is at its strongest when the arm  4  is horizontal and the cover B is closed. The repelling force of the spring  30  is at its weakest when the arm  4  is vertical and the cover B is open. There is no great difference in the repelling force of the spring  31  with regard to the up and down movements of the second base  9  because it is pushing the forward link  2  with the pin  32  positioned at a location slightly separated from the pin  14  as the pivoting point. 
     The function of the spring  8  as shown in FIG.  1  and FIG. 5 is the same as the function of the usage of the two springs  30  and  31  in FIG.  9 . Furthermore, as the spring  30  and spring  31  perform the hinging movement of the cover B and the raising and lowering independently, there is no variation in the moment for raising and lowering by the hinging action of the cover B and there is no variation in the moment of the hinging action by the raising and lowering of the cover B. Therefore, the two springs of  30  and  31  in the hinge apparatus are possible if ample space is provided for their attachment. If such an ample space is not available, it is possible to use the one spring  8  as is shown in the hinge  1  and  101  in FIG.  1  and FIG.  5 . 
     Here, we will provide an explanation of the hinge apparatus  201  in FIG.  10  and FIG. 11 by comparing to the hinge apparatus  1  and  101  in FIG.  1  and FIG.  5 . 
     FIG.  10  and FIG. 11 show the side view and top view respectively of the hinge apparatus  201  and FIG.  12  and FIG. 13 are the perspective side view and the perspective plan view of the hinge apparatus  201 . As is clear in the FIGs, the base  207 , the arm  204 , the lock arm  205 , the forward link  202 , the rearward link  203  and the second base  209  are established symmetrically along the lines E and E in FIG. 11 and B and B FIG.  13 . Particularly, the base  207 , the arm  204 , the lock arm  205 , the forward link  202 , the rearward link  203  and the second base  209  are single plates that have been symmetrically bent along the lines E and E. Furthermore, both sides of the side of the apparatus shown in the side views of FIG.  10  and FIG.  12  and the opposing side of that same apparatus each fulfill the same roles of the base  207 , the arm  204 , the lock arm  205 , the forward link  202 , the rearward link  203  and the second base  209  as shown in FIG.  5 . Also, the two piece plate rearward link  203  is connected to the arm  204  and the second base  209  in the same way as the rearward link  3  in FIG.  5 . The second base  209  has the plate  209   a  expanding outwardly at both ends. A plurality of screw holes  209   b  are established on the plate  209   a . Therefore, a part of the second base  209  is inserted into a part of the cover B having a thickness for opening and closing the platen glass and when the plate  209   a  on the second base  209  is positioned with a part of the cover B, and a screw is passed through the screw hole  209   b  to be a screw stopper, the hinge apparatus  201  and the cover B can be linked. 
     The pins linking each of the composing parts (the pins  212 ,  213 ,  214 ,  215 ,  216 ,  217 ,  218  and  219 ) correspond to the pins (the pins  12 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18  and  19 ) in FIG.  5 . 
     Excluding the pin  213  and the pin  215 , each pin is one pin extending to both sides of the apparatus and each pin passes through the parts related to the pins to link the parts mutually composing on both sides. 
     The pin  216  which passes through both sides of the lock arm  205  passes through the slide aperture  224  established at the arm  204 . The outer circumference of that pin is in contact with the straight sided cam section  102   b  of the cam  102   a  on the forward link  202 . Also, inside of the hinge  201  a lock roll  206  is established that rotates on the circumference co-axially with the pin  216 . The lock roll  206  rolls along the inner lower surface of the arm  204  because the lock arm  205  and the pin  216  slidingly swing. 
     Referring to the sectional view of FIG.  12  and the partially sectional view of FIG. 13 a spring  208  equivalent to that of the spring  8  in FIG. 5 is centrally established inside of the hinge apparatus  201 . The ends of the spring  208  are connected to the guide  221   a  and the guide  222   b . Furthermore, the guide  221   a  and the guide  222   b  are connected to the pin  217  and the pin  219  passing through the inside of the apparatus. The guide  221   a  and the guide  222   b  have substantially flat surfaces to accept the entire surface of the spring  208  in order to prevent bending when expanding and contracting the spring  208 . The opposite side of that surface when looking from the side is elliptical. Also, the forward link  202  has the lift cam  220  permanently attached to the inside. One side of the lift cam  220  is connected to the pin h 19  which transmits the expanding tension force from the spring  208  to the forward link  202 . 
     Returning to FIG. 10, a stopper  211  is established in the hinge apparatus to adjust the position of the arm  204  so that the cover B is parallel with the platen C when it is closed and to restrict the action of the right rotation of the arm  204 . Stopper  211  is established along the side wall  207  of the base  207  and has a bent and flat surface  211   b  at the top. This makes contact with the end of the screw  221  attached to the top part of the side wall  207   a.    
     FIG. 14 is a sectional view looking from the direction of the stopper  211  on the hinge apparatus  201  when the position has been adjusted using the stopper  211 . The stopper  211  has a flat surface contacting the surface of the side wall  207   a  of the base  207  and on that flat surface is a hole  211   c  extending up and down. The screw  232  passes through the screw hole  211   c  to fasten the side wall  207   a  on the base  207  and the stopper  211 . The stopper  211  can move freely up or down along the side wall  207   a  when the screws  222  is loosened. However, the upper part flat  211   b  on the stopper  211  restricts the up and down movement of the screw  221 . Also, there is a member expanding to the outside on the stopper  211 . Looking at FIG. 10, the arm  204  expands beyond a part of the stopper  211 . The receiver part  211   a  which extends on the stopper  211  and the abutting part  204   b  which extends on the arm  204  are established so that they make contact. Therefore, the arm  204  cannot rotate to the right any further because of the contact of the receiver member  211   a  and the abutment member  204   b . FIG. 10 shows the movement in the upward direction of the stopper  211  restricted by the contact of the tip of the screw  211  by the flat member  211   b  on the stopper  211  and the state in which the receiver part  211   a  contacts the abutment part  204   b  and the arm  204  cannot rotate any further to the right. Also as shown in FIGS.  14 (A) through (C), tightening or loosening the screw  221  raises or lowers the screw in the up or down directions and along with the movement of the stopper  211  in the upward or downward directions, the arm  204  rotates to the left or to the right making it possible to adjust the second base  209  and the angle of the cover B attached therein. This makes it possible to adjust the parallelism of the cover B and the platen C if there is a discrepancy in the attachment of the cover B and the second base  209  or if there is a discrepancy in the angle of the attachment of the platen C and hinge apparatus  201 . By tightening the screw  222 , the stopper  211  and base  207  can be maintained at the optimum fastening position.