JP5581902B2 - Ring binding apparatus and image forming system provided with the ring binding apparatus - Google Patents

Description

  The present invention relates to a ring bookbinding apparatus that binds printed sheet bundles with a ring binder and an image forming system including the ring bookbinding apparatus.

  In recent years, image forming systems have been equipped with post-processing devices that perform various post-processes in addition to simply printing, and have been designed to improve the efficiency of office processing. Examples of post-processing include punch processing, stapling processing, inserter processing for inserting a cover or insertion paper, folding processing such as half-folding and tri-folding, and bookbinding processing.

  One of the bookbinding processes is a ring bookbinding process. This ring bookbinding process is performed by attaching a ring binder shown in Patent Document 1, for example, to a plurality of holes formed in a sheet bundle and closing the ring. Is bound and a booklet as shown in FIG. 8 is created.

  Patent Document 2 discloses another example of a ring binder (binding tool) used for ring binding. The ring binder disclosed in Patent Document 2 has one spine portion and a plurality of finger-like portions extending from the spine portion. The finger-like portions are inserted into punch holes of the sheet bundle, and rolled to the spine portion. By connecting, it is a structure that forms a round ring binder. This ring binder can change the position where the finger-like part is connected to the spine part according to the thickness of the booklet, and the diameter of the ring binder can be set to an appropriate size.

JP 2007-30319 A Special table 2008-505787 JP 2006-15615 A

  Conventionally, the position of the hole through which the ring binder passes in the ring binding apparatus is a fixed position from the edge of the paper. For this reason, as shown in FIG. 9A, the paper bundle before binding has the same hole position. However, when binding with a ring binder, the sheet bundle follows the curvature of the ring binder as shown in FIG. 9B. The hole position of each sheet is shifted. For this reason, the end face F on the opposite side of the booklet BK has a shape in which the center is swollen, and the appearance is poor.

  Patent Document 3 discloses a technique for changing the hole position for each album by ring diameter, booklet thickness, booklet size, etc., when various albums are bound into a book. This facilitates turning of the paper as the hole position corresponding to the album to be produced. However, since the hole positions of the sheets in one type of album are the same, the end face F on the opposite side of the album has a shape in which the center swells as shown in FIG. 9B.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a ring bookbinding apparatus that can perform bookbinding with excellent end-face bookbinding and an image forming system including the ring bookbinding apparatus.

The above object can be achieved by the following configuration. That is,
1. A setting means for changing and setting a hole position of a hole for a ring binder provided on one side of the sheet bundle for each sheet or a plurality of sheets constituting the sheet bundle;
A punching means for punching a plurality of holes at the punching position set by the setting means, comprising a stopper movable in the paper transport direction, and the stopper has moved according to the punching position set by the setting means A punching means for stopping the paper at the position and punching at this position ;
Paper storage means for storing and aligning a plurality of punched papers into a paper bundle;
A ring binding means for attaching a ring binder to the aligned paper bundle and performing ring binding;
A ring bookbinding apparatus that performs ring binding with the sides of the sheet bundle aligned.

For more details,
2. A setting means for changing and setting a hole position of a hole for a ring binder provided on one side of the sheet bundle for each sheet or a plurality of sheets constituting the sheet bundle;
A punching means for punching a plurality of holes at the punching position set by the setting means, the punching means configured to be movable in the paper transport direction in accordance with the punching position set by the setting means. A drilling means for drilling;
Paper storage means for storing and aligning a plurality of punched papers into a paper bundle;
A ring binding means for attaching a ring binder to the aligned paper bundle and performing ring binding;
A ring bookbinding apparatus that performs ring binding with the sides of the sheet bundle aligned.
3. The setting means includes an acquisition means for acquiring the number and thickness of the sheets constituting the sheet bundle and a parameter of the ring binder, and a punching position for each sheet or a plurality of sheets based on the numerical values acquired by the acquisition means. The ring bookbinding apparatus according to 1 or 2 , further comprising: a calculating unit that calculates.
4). 4. The ring binding apparatus according to 3 , wherein the parameter of the ring binder is curvature data of an inner peripheral surface of the ring binder.
5. The ring bookbinding apparatus according to any one of claims 1 to 4 , wherein the punching position of the sheet bundle is set in an arc shape along an inner peripheral surface of the ring binder.
6). 1 to 5 above, wherein the distance in the direction along the paper surface of the clearance provided between the inner peripheral surface of the ring binder and the edge of the paper hole is 1 mm <B <3 mm. The ring binding apparatus as described in any one of Claims.
7). The punching means has a transport roller for transporting the paper toward the punching position and a sensor provided upstream of the punching position, and determines the distance from when the sensor detects the leading edge of the paper to when the paper is stopped. The ring bookbinding apparatus according to any one of 1 to 6 , wherein the ring binding apparatus is changed in accordance with a drilling position set by the setting means.
8). An image forming apparatus that forms an image on a sheet, and the ring binding apparatus according to any one of 1 to 7 that performs ring binding on a bundle of sheets on which an image is formed by the image forming apparatus. An image forming system characterized by that.

  According to the present invention described above, it is possible to provide a ring bookbinding apparatus capable of performing excellent bookbinding with the flat end faces of the booklet and an image forming system including the rebuy bookbinding apparatus.

1 is a cross-sectional view illustrating an image forming system to which the present invention is applied. The expanded sectional view which shows the ring bookbinding apparatus to which this invention is applied. The fragmentary sectional view which expands and shows the ring bookbinding apparatus of the 1st Embodiment of this invention. Sectional drawing and the elements on larger scale which show the booklet which carried out the ring binding by this invention. The flowchart which shows the control which concerns on this invention. The figure which shows an example of the table of the data used for this invention. The elements on larger scale of the ring bookbinding apparatus which shows the 2nd Embodiment of this invention. The perspective view which shows the booklet by which ring binding was carried out. Sectional drawing which shows the state of the booklet ring-bound by the prior art.

  FIG. 1 is a sectional view showing an image forming system to which the present invention is applied. This image forming system includes a large-capacity paper feeding device LT, an image forming device IF, an inserter device IN that inserts a cover and partition paper into a sheet bundle, a ring binding device LG, and a finisher device FN that performs various post-processing from the right side of the figure. It is a connected system.

  The image forming apparatus IF is a device that forms an image by an electrophotographic method, an offset printing method, or the like, and has an operation panel OP that is a display input unit. The large-capacity paper feeder LT has a plurality of paper feed stages and supplies paper to the image forming apparatus IF. The paper can also be fed from a paper feed stage built in the image forming apparatus IF.

  The inserter IN is equipped with three paper feed trays IT1, IT2, and IT3, one in the upper two stages and one in the inside, and can set cover sheets and partition sheets of different colors and thicknesses, from the operation panel OP. Based on the input instruction, the paper is inserted into a predetermined position of the paper bundle.

  Further, the finisher device FN includes a punch unit FN1 that performs a two-hole punch for a file, a flat stitch unit FN2 that performs a side stitch, a saddle stitch unit FN3 that performs a saddle stitch, and a folding unit FN4 that folds a sheet in three or three. Then, after various post-processing is performed on the paper, it is discharged to the lifting tray T1 or the lower tray T2.

  Each device has control units CL1 to CL5, and performs image formation and post-processing while communicating with each other via a communication line.

  The above image forming system is an example, and it is needless to say that other configurations may be used.

  FIG. 2 is an enlarged cross-sectional view of the ring bookbinding apparatus LG to which the present invention is applied. First, the outline of the ring bookbinding apparatus will be described with reference to this figure.

  In the figure, a horizontal conveyance path 1 is provided across the central upper part, conveys paper from the upstream, and delivers it to the downstream finisher FN. A paper feed tray 2 is provided in the upper part of the apparatus. When offline ring binding is performed, paper is sequentially fed from the paper feed tray 2 and joined to the horizontal conveyance path 1. A paper discharge tray 3 is also provided at the top of the apparatus so that paper that is not subjected to post-processing by the finisher device FN can be discharged to the paper discharge tray 3.

  A bookbinding transport path 10 that branches downward from the center of the horizontal transport path 1 is a transport path for transporting paper for ring binding. The sheet passes through the bookbinding transport path 10 and is temporarily transported upward on the obliquely arranged tray 11 and is transported downward according to the punching position control described later when the rear end of the sheet is removed from the bookbinding transport path 10.

  Such switchback conveyance is performed for the following reason. In other words, a booklet that is ring-bound is often printed on both sides of the booklet sheet and viewed with a spread. In double-sided printing, the front and rear edges of the paper are interchanged because the paper is turned over during backside printing. For this reason, in order to return the leading edge and the trailing edge of the sheet to the original position, the edge of the sheet on which the hole is to be punched is performed by performing the switchback conveyance.

  However, it is also possible to simply perform straight conveyance in which the paper is sent from the horizontal conveyance path 1 to the bookbinding conveyance path 10. In this case, a reverse conveyance path for switching the leading and trailing edges of the paper is provided upstream of the bookbinding conveyance path 10 of the image forming apparatus IF, the inserter IN, or the ring bookbinding apparatus, and this reverse conveyance path is used for duplex printing. You may make it pass.

  A plurality of holes for ring binding are punched in the stopped paper by the punching device 12. The punching device 12 is a known mechanism having a die, a punch, a cam for driving the punch, and a container for storing punch scraps, and can punch holes as many as the number of rings of the ring binder in the paper.

  The perforated sheet moves downward along the second tray 13 and stops by hitting a stopper (not shown). When a predetermined number of sheets are collected, the gripper 14 holds the end of the sheet bundle. The gripper 14 is configured such that one gripper is fixed and the other gripper is movable, and the movable gripper moves to sandwich the sheet bundle.

  Two cartridges 15 and 16 are arranged on the right side of the center of the figure. The cartridges 15 and 16 contain ring binders LB of different sizes, and are configured to be movable in the horizontal direction by a moving mechanism (not shown) so that one of the cartridges is moved to the take-out position. The dotted line shown on the right side of the solid cartridge indicates the state where the left cartridge 15 has moved to the removal position.

  A ring binding mechanism 17 is located below the take-out position, and the ring bind mechanism 17 is rotated around the shaft 18 to move between the take-out position and the bind position.

  The ring binding mechanism 17 takes out one ring binder LB from the cartridge at the take-out position, moves to the bind position, and attaches the ring binder to the end of the sheet bundle held by the gripper 14. The mounting method is performed by a known method such as the method described in Patent Document 1.

  The booklet equipped with the ring binder moves along the belt conveying device 19 (broken line position) below the gripper 14 and stops by hitting the stopper SP1. Then, the belt conveyance device 19 is rotated to the solid line position in the figure, and the belt is driven counterclockwise to deliver the booklet to the second belt conveyance device 20. The second belt conveyance device 20 conveys the booklet and discharges it to a discharge tray 21 that can be raised and lowered. A portion of the illustrated frame line including the tray 21 is configured to be pulled out toward the front side of the apparatus, and a booklet that has been bound into a ring can be taken out.

  Now, the present invention provides a ring bookbinding apparatus that can be used as a booklet having a good appearance by aligning the end surfaces of booklets that have been bound by a ring. FIG. 4A is a view showing a booklet BK bound by ring according to the present invention. The right end face F of the booklet BK, that is, the end face F on the opposite side to the end face on which the ring binder is mounted looks flat and looks good. It is in good condition. In order to perform such ring binding, in the present invention, the drilling position of the hole for the ring binder is changed for each sheet or for a plurality of sheets. Accordingly, the envelope connecting the edges of the ring binder holes of each sheet becomes a hole curved in an arc shape.

  A first embodiment in which the punching position is changed for each sheet or a plurality of sheets as described above will be described with reference to FIG.

  FIG. 3 is a partial cross-sectional view further enlarging a perforation device portion of the ring bookbinding apparatus of FIG. 2. In FIG. 3, a switching gate G is provided at a branch point from the horizontal conveyance path 1 to the bookbinding conveyance path 10, and the conveyance path is switched according to the mode.

  The bookbinding transport path 10 has a guide plate curved in an S-shape and a transport roller 10 a and guides the paper to the tray 11. A sensor SS is provided at the exit of the bookbinding transport path 10 so as to face the tray 11 and detects the edge of the paper. The tray 11 is provided with transport rollers 11a and 11b. The transport rollers 11a and 11b are driven by a pulse motor, rotate in the forward direction and the reverse direction, and control the stop position of the sheet by controlling the number of pulses. Do.

  In the configuration shown in FIG. 3, when a sheet is fed, the sheet is fed upward along the tray 11 by the transport rollers 11a and 11b. When the trailing edge of the sheet is detected by the sensor SS, the sheet is temporarily stopped. Then, the transport rollers 11a and 11b rotate in the reverse direction to transport the paper to a position based on information on a hole punching position, which will be described later, by controlling the number of drive pulses. When the paper reaches a predetermined position, the transport rollers 11a and 11b are stopped, and the punching device 12 (punch 12a and die 12b) is operated to punch a hole for a ring binder in the paper. This operation is performed by changing the paper stop position for each sheet or for a plurality of sheets.

  The paper having the holes punched in this manner moves downward along the second tray 13 and stops by hitting a stopper (not shown). When a predetermined number of papers are collected, the above-described ring binding mechanism 17 performs ring binding. . As shown in FIG. 4A, the ring-bound booklet BK is a booklet with a good appearance, with the end face F on the opposite side of the ring binder being flat.

  In the present invention, the hole punching position is changed for each sheet or a plurality of sheets as described above, and the concept of setting / changing the punching position at that time will be described with reference to FIG. explain.

Now, let us say that the booklet BK bound in accordance with the present invention has a point P where the center of the ring binder coincides with the midpoint of the end of the booklet. The hole punching position (distance from the edge of the paper to the edge of the hole) for the booklet cover (or back cover) paper is A _MIN , and the hole punching position for the paper in the center of the booklet thickness direction (paper at point P) Is A _MAX , the inner diameter of the ring binder is 2r, and the thickness of the booklet is 2T,
A _MIN = (T / tan θ) −B
A _MAX = r-B
Can be expressed as Where θ is an angle formed by a line connecting point Q and point P where the cover (or back cover) of the sheet intersects the inner diameter of the ring binder and a line extending horizontally from point P, and B is the inner diameter of the ring binder. This is the distance in the direction along the paper surface of the clearance provided between the edge of the paper hole.

From the figure, since sin θ = T / r, tan θ = T / √ (r ² −T ² ) is obtained, and A _MIN and A _MAX are obtained from these equations, and the punching position for each sheet between them is determined as the hole position. What is necessary is just to obtain | require by an interpolation calculation so that an envelope may become substantially the same as the internal diameter of a ring binder.

On the other hand, the perforation position (distance from the end of the sheet to the end of the hole) of an arbitrary sheet is A _X , the distance from the booklet end midpoint of the sheet is T _X , and the position Q at which this sheet intersects the inner diameter of the ring binder And the angle formed by the line connecting point P and θ _X is
A _X = (T _X / tan θ _X ) −B
It becomes. The perforation position of each paper hole may be obtained from this equation.

  In the above description, the center of the ring binder and the midpoint of the booklet edge coincide with each other at the point P because the booklet that is bound by the ring is often used in a two-page spread. This is because it is most preferable that the page end face of the spread is located on the left and right in the center of the binder.

  The clearance B may be set as appropriate according to the type of the ring binder and the like, but 1 mm <B <3 mm is preferable considering the dimensions of the ring binder that is normally used.

  Actually, the thickness of the booklet that can be bound to the inner diameter of the usable ring binder is determined within a certain range. Therefore, the hole of each paper is punched according to the type (inner diameter) of the ring binder and the thickness of the booklet. The positions may be stored as a table, and the hole drilling position information may be called from this table and drilled. The thickness of the booklet can be determined from the paper type (thickness or basis weight) of the paper to be used and the number of sheets.

  FIG. 5 is a flowchart showing an outline of the control for performing the ring binding process with variable perforation position as described above. This flowchart collectively shows the control related to ring bookbinding, but actually, the control is performed by the control unit CL1 of the image forming apparatus IF and the control unit CL4 of the ring bookbinding apparatus LG. The upper part from the operation panel OP is input to the control unit CL1, and both serve as setting means.

  When the control of the flowchart of FIG. 5 starts, first, in a subroutine of step S1, control such as switching the switching gate G (see FIG. 3) to the bookbinding transport path 10 side to initialize the ring bookbinding apparatus LG or perform ring bookbinding is performed. It is done, and it prepares for ring binding.

  Next, in step S2, it is determined whether or not to set conditions for flattening the booklet end surface opposite to the ring binder in ring binding. This determination is made by examining the input on the condition setting screen of the operation panel OP of the image forming apparatus IF.

  When the condition is set in step S2 (Yes), the process proceeds to step S3, the number of sheets used for the booklet and the sheet type (thickness or basis weight) are set, and the set number of sheets and sheet type (thickness). Or the basis weight), the thickness of the booklet is calculated. In the next step S4, the type of ring binder to be used (symbol indicating the type or inner diameter) is set. The settings in step S3 and step S4 are also performed on the condition setting screen.

  Whether or not the ring binder can be used is determined in step S5 from the thickness of the booklet obtained in step S3 and the type of ring binder set in step S4. This is because good ring binding may not be possible with the type of ring binder selected by the operator.

  If No in step S5, the process returns to step S3 and the setting is performed again. If there is no suitable ring binder even after re-execution, a cartridge of a different type of ring binder may be mounted on the ring binding device LG and the above steps may be repeated.

  If Yes in step S5, the process proceeds to step S6 to calculate the hole drilling position. This calculation is performed by selecting a table stored in the memory of the control unit CL4.

FIG. 6 shows an example of the table. For example, the sheet of the body sheet of the booklet basis weight 104.7 g / ^{m 2} (thickness 0.11mm in quality paper) using 50 sheets, respectively on the front cover and the back cover s basis weight 209.4g / ^{m 2} (fine When ring binding is performed using paper having a thickness of 0.23 mm, the thickness of the booklet is about 6 mm. For this booklet, it is assumed that a ring binder having an inner diameter of 10 mm is selected and ring-bound. In the example of FIG. 6, the amount of change of the punching position is set to 0.1 mm, and the number of holes is changed as it approaches the front cover and the back cover.

The table shown in FIG. 6 is set with A = A _MIN = 2 mm, A _MAX = 3 mm, and B = 2 mm, but this is only an example. For example, the change amount is further reduced or the change amount is stepped. Alternatively, the number of sheets with the same change amount may be adjusted to increase or decrease. A plurality of such tables are prepared according to the type of ring binder and the thickness of the booklet, and stored in the memory.

  Returning to the flowchart of FIG. 5, after step S6, the image forming apparatus IF starts printing in step S7. In step S8, each sheet sent from the image forming apparatus IF is set to the punching position in FIG. Set and drill. When all the sheets are punched, the sheet bundle is moved to the bookbinding position in step S9, and the ring bookbinding process is performed in step S10.

  On the other hand, in the case of No in step S2, it is a case where the process for flattening the end face is not performed, for example, when the thickness of the booklet is thin and flattening of the end face is unnecessary, or when the appearance is not minded in the in-house document is there. At this time, the process proceeds to step S11, and the type (symbol indicating the type or inner diameter) of the ring binder to be used is set, printing is started in step S12, and the punching position is fixed in step 13 for punching. When all the sheets have been punched, processing is performed in steps S9 and S10.

  As described above, since the hole punching position of the sheet to be bound to the ring is changed, the end face of the booklet that has been bound to the ring can be flattened, so that the booklet with a good appearance can be obtained.

  The change of the punching position described above is performed by controlling the stop position of the conveying roller by the drive control of the pulse motor, while stopping the sheet in the punching apparatus, but other methods are also possible. The second embodiment will be described below.

  FIG. 7 shows an embodiment in which the paper is stopped in the punching device 12 by a stopper SP2 whose position can be changed. Specifically, the punching device 12 is provided with a stopper SP2 extending from between the dies 12b to the paper conveyance path. A plurality of punches and dies are arranged in the direction perpendicular to the paper surface, and a plurality of stoppers SP2 are provided therebetween. The stopper SP2 can be rotated between an intrusion position for stopping the sheet and a retracted position for retracting from the sheet conveyance path as indicated by an arrow A, and the entire stopper SP2 is parallel to the sheet conveyance path in the direction of the arrow A. It is provided on a moving member 12c that is movably held. The mechanism for rotating the arrow A and the parallel movement of the arrow B is not shown, but a known mechanism can be used.

  With the above configuration, when the hole punching position for each sheet is changed, the moving member 12c moves back and forth in parallel with the sheet conveying direction to change the position of the stopper SP2, thereby adjusting the hole punching position. is there. The setting for changing the drilling position can be similarly performed using the above-described flowchart of FIG. 5 and the table of FIG. Although the stopper SP2 is provided inside the punching device 12, if the size of the punching device 12 can be reduced, it can be provided outside the punching device.

  As a further modification, the entire punching device 12 may be configured to move in the paper transport direction. The punching means described in the claims includes the tray 11 in the first embodiment, the transport rollers 11a and 11b that stop the paper at the punching position, the sensor SS, and the punching device 12, and the movable member of the second embodiment. The punching device 12 having the stopper SP2 or the punching device 12 in which the entirety of the modification is movable corresponds.

  The above is an embodiment in which the drilling position of the hole for the ring binder is changed, but the hole size can be changed as another modification. In other words, if the size of the hole is made larger at the center of the paper bundle and smaller toward the front cover and back cover, the edge of the hole on the outer diameter side of the ring binder becomes an arc, and the end face of the booklet is Can be flat.

  Further, the ring binder described so far is described in Patent Document 1, but it goes without saying that the present invention can also be applied to the ring binder disclosed in Patent Document 2. At this time, since the ring binder of Patent Document 2 can change the position where the finger-like part is bonded to the spine part according to the thickness of the booklet, the diameter of the ring binder can be made according to the thickness of the booklet. Therefore, in this case, the diameter of the ring binder (position where the finger-shaped portion is bonded to the spine portion) is first determined from the thickness of the booklet, and then the hole drilling position is set in the same manner as described above.

IF image forming apparatus OP operation panel LG ring binding apparatus LB ring binder BK booklet 10 bookbinding transport path 11, 13 tray 11a, 11b transport roller SS sensor 12 punching apparatus 12a punch 12b die 12c moving member SP1, SP2 stopper 14 gripper 15, 16 Cartridge 17 Ring binding mechanism 19, 20 Belt conveyor

Claims (8)

A setting means for changing and setting a hole position of a hole for a ring binder provided on one side of the sheet bundle for each sheet or a plurality of sheets constituting the sheet bundle;
A punching means for punching a plurality of holes at the punching position set by the setting means, comprising a stopper movable in the paper transport direction, and the stopper has moved according to the punching position set by the setting means A punching means for stopping the paper at the position and punching at this position ;
Paper storage means for storing and aligning a plurality of punched papers into a paper bundle;
A ring binding means for attaching a ring binder to the aligned paper bundle and performing ring binding;
A ring bookbinding apparatus that performs ring binding with the sides of the sheet bundle aligned. A setting means for changing and setting a hole position of a hole for a ring binder provided on one side of the sheet bundle for each sheet or a plurality of sheets constituting the sheet bundle;
A punching means for punching a plurality of holes at the punching position set by the setting means, the punching means configured to be movable in the paper transport direction in accordance with the punching position set by the setting means. A drilling means for drilling;
Paper storage means for storing and aligning a plurality of punched papers into a paper bundle;
A ring binding means for attaching a ring binder to the aligned paper bundle and performing ring binding;
A ring bookbinding apparatus that performs ring binding with the sides of the sheet bundle aligned. The setting means includes an acquisition means for acquiring the number and thickness of the sheets constituting the sheet bundle and a parameter of the ring binder, and a punching position for each sheet or a plurality of sheets based on the numerical values acquired by the acquisition means. ring binding device according to claim 1 or 2, characterized in that it has a calculation means for calculating. The ring binding apparatus according to claim 3 , wherein the parameter of the ring binder is curvature data of an inner peripheral surface of the ring binder. The ring bookbinding apparatus according to any one of claims 1 to 4 , wherein the punching position of the sheet bundle is set in an arc shape along an inner peripheral surface of the ring binder. When the direction of the distance along the paper surface of the clearance provided between the inner peripheral surface and the edge of the hole of the sheet ring binder is B, the preceding claims, characterized in that a 1mm <B <3mm 5 The ring bookbinding apparatus according to any one of the above. The punching means has a transport roller for transporting the paper toward the punching position and a sensor provided upstream of the punching position, and determines the distance from when the sensor detects the leading edge of the paper to when the paper is stopped. The ring bookbinding apparatus according to any one of claims 1 to 6 , wherein the ring binding apparatus is changed according to a drilling position set by the setting means. An image forming apparatus that forms an image on a sheet, and a ring binding apparatus according to any one of claims 1 to 7 that performs ring binding on a bundle of sheets on which an image is formed by the image forming apparatus. An image forming system comprising:

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