Patent Description:
Lamination technologies are known in the art that insert an inner sheet (e.g., paper or photo) between a two-ply lamination sheet or lamination film (e.g., a lamination pouch or lamination folder) and apply heat and pressure to the two-ply lamination sheet to bond the two-ply lamination sheet. The two-ply lamination sheet is made of two sheets (plies) bonded (sealed) on one side as if one sheet is folded.

The sheet laminator that performs a sheet laminating operation includes a thermal fixer that applies heat and pressure to the two-ply sheet. The thermal fixer includes a pair of thermal fixing rollers that are heated and rotated to form a nip region through which the two-ply sheet passes. The two-ply sheet that nips a sheet medium passes through the nip region, so that the two-ply sheet can be thermally fixed (adhered).

<CIT> discloses a laminator assembly having a pressure roller with a deformable layer.

A fixing device of an image forming apparatus (hereinafter, referred to as a "fixing device") is known in the technical field of thermal fixing. The fixing device typically includes a heat roller for heating an image forming face of a recording medium and conveying the recording medium and a pressure roller for pressing the other face (non-image forming face) of the recording medium and conveying the recording medium. With the heat roller and the pressure roller, the fixing device performs a fixing process by heating and pressing the recording medium.

For example, a fixing device disclosed in <CIT> has a configuration in which an elastic layer is provided on a core metal portion of a fixing roller and a heat-resistant release layer made of, for example, fluororesin is formed on a surface layer for the purpose of reducing thermal damage to a fixing configuration (member). In addition, also the disclosed fixing device also has a configuration (such as a temperature sensor and a drive device) for switching an abnormal temperature detection level according to the operation state of the fixing device.

However, when the configuration of the fixing device is applied to (the thermal fixing unit of) a sheet laminator, the following problems occur.

The heat roller and the pressure roller of the fixing device are different in material and rigidity from each other, the curvature of the nip region increases. If this configuration is applied to the sheet laminator, the two-ply sheet (made of resin) is heated with a relatively large curvature, and the sheet after thermal fixing is curled.

The fixing device is provided with a fluororesin layer having good releasability only on the surface layer of the heat roller for the purpose of collecting the residual toner remaining on the surface of the pressure roller that is the non-image surface. When this configuration is applied to the sheet laminator, the glue (adhesive) oozing from the two-ply sheet (lamination film) adheres to one roller side, and the sheet sticks to and winds around the roller.

Once the two-ply sheet is wound around the roller, it is not easy for an ordinary user to remove the two-ply sheet, and the sheet laminator needs to be repaired by a specialist. To prevent this problem, each time the sheet laminator is used, a cleaning sheet is passed through the sheet laminator to remove the glue or adhesive adhering to the roller, which is a burden on a user.

In view of the above-described disadvantages, an aim of the present disclosure is to provide a thermal fixer, a sheet laminator including the thermal fixer, and an image forming system incorporating the sheet laminator, that can disperse adhesive oozed from the two-ply sheet to the rollers of the thermal fixing roller pair, prevent the winding of the two-ply sheet around the thermal fixing rollers, and achieve the stable lamination quality with less curling.

According to the present invention, there is provided a thermal fixer as defined in claim <NUM>. Embodiments of the present disclosure described herein provide a novel thermal fixer including a first thermal fixing roller and a second thermal fixing roller. The first thermal fixing roller includes a first heater. The second thermal fixing roller is pressed to the first thermal fixing roller. The second thermal fixing roller includes a second heater and has a diameter, a rigidity, and a surface releasability substantially identical to the first thermal fixing roller.

Further, embodiments of the present disclosure described herein provide a sheet laminator including the above-described thermal fixer. The thermal fixer thermally fixes and conveys a two-ply sheet and a sheet medium nipped between two sheets of the two-ply sheet in a sheet conveyance direction.

Further, embodiments of the present disclosure described herein provide an image forming system including the above-described sheet laminator including the thermal fixer, and an image forming apparatus to form an image on a sheet medium to be supplied to the sheet laminator.

According to the present disclosure, a thermal fixer included in a sheet laminator includes the thermal fixing roller pair having a substantially same diameter, a substantially same rigidity, and a substantially same surface releasability. Due to such a configuration, the thermal fixer, the sheet laminator including the thermal fixer, and an image forming system including the sheet laminator can disperse adhesive oozed from the two-ply sheet to the rollers of the thermal fixing roller pair, prevent the winding of the two-ply sheet around the thermal fixing rollers. In addition, as the thermal fixer included in the sheet laminator can heat and press the two-ply sheet equally from both sides, the stable lamination quality with less curling can be achieved.

Exemplary embodiments of this disclosure will be described in detail based on the following figures, wherein:.

It will be understood that if an element or layer is referred to as being "on," "against," "connected to" or "coupled to" another element or layer, then it can be directly on, against, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, if an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, then there are no intervening elements or layers present. As used herein, the term "connected/coupled" includes both direct connections and connections in which there are one or more intermediate connecting elements.

Spatially relative terms, such as "beneath," "below," "lower," "above," "upper" and the like may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. For example, if the device in the figures is turned over, elements describes as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, term such as "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated <NUM> degrees or at other orientations) and the spatially relative descriptors herein interpreted accordingly.

The terminology used herein is for describing particular embodiments and examples and is not intended to be limiting of exemplary embodiments of this disclosure. It will be further understood that the terms "includes" and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

<FIG> is a diagram illustrating an overall configuration of a sheet processing device according to an embodiment of the present disclosure.

A sheet processing device <NUM> according to the present embodiment is to separate two sheets (plies) of a two-ply sheet (hereinafter referred to as a lamination sheet S) and to insert and sandwich a sheet-shaped medium (hereinafter referred to as an inner sheet P) between the separated sheets of the two-ply sheet.

The lamination sheet S is a two-ply sheet in which two sheets are overlapped and bonded together at a portion (or a side) at the bonded portion r of the two-ply sheet. For example, a two-ply sheet has two sheets (two sides). A first side of the two-ply sheet serves as a transparent sheet such as a transparent polyester sheet, a second side of the two-ply sheet serves as a transparent or opaque sheet is disposed facing the first side, and the first and second sides are bonded at one side of the two-ply sheet. Examples of the two-ply sheet also include a lamination film.

The inner sheet P is an example of the sheet medium that is inserted into the two-ply sheet. Examples of the sheet medium include thick paper, postcards, envelopes, plain paper, thin paper, coated paper, art paper, tracing paper, and overhead projector (OHP) transparencies.

As illustrated in <FIG>, the sheet processing device <NUM> includes a sheet tray <NUM>, a pickup roller <NUM>, and a conveyance roller pair <NUM>. The sheet tray <NUM> serving as a first sheet stacker on which the two-ply sheets S are placed. The pickup roller <NUM> feeds the two-ply sheet S from the sheet tray <NUM>. The sheet processing device <NUM> further includes a sheet tray <NUM> as a second sheet stacker on which the inner sheet P is stacked, and a pickup roller <NUM> that feeds the inner sheet P from the sheet tray <NUM>.

The sheet tray <NUM> includes a sheet size sensor C6 that serves as a sheet size detector to detect the size of the lamination sheet S, in other words, the length of the lamination sheet S in the sheet conveyance direction. The sheet tray <NUM> includes a sheet size sensor C7 that serves as a medium size detector to detect the size of the inner sheet P, in other words, the length of the inner sheet P in the sheet conveyance direction.

Each of the sheet size sensor C6 and the sheet size sensor C7 includes a plurality of sensors arranged side by side in the sheet conveyance direction. Since the detection results of the sensors change depending on the size of the stacked lamination sheets S and the inner sheets P, the sheet size sensors C6 and C7 can detect the length of the lamination sheet S and the insertion sheet P in the sheet conveyance direction.

A sheet conveyance sensor C1 is disposed downstream from the conveyance roller pair <NUM> in the sheet conveyance direction to detect the sheet conveyance position of the two-ply sheet S.

A sheet conveyance sensor C2 is disposed downstream from the pickup roller <NUM> in the sheet conveyance direction to detect the sheet conveyance position of the inner sheet P.

The sheet conveyance sensors C1 and C2 may be used to detect the length of the lamination sheet S (or the inner sheet P) in the sheet conveyance direction.

The sheet processing device <NUM> further includes an entrance roller pair <NUM> as a first conveyor, a winding roller <NUM> as a rotary member, an exit roller pair <NUM> as a second conveyor, and a sheet ejection tray <NUM>. The entrance roller pair <NUM>, the winding roller <NUM>, the exit roller pair <NUM>, and the sheet ejection tray <NUM> are disposed downstream from the conveyance roller pair <NUM> and the pickup roller <NUM> in the sheet conveyance direction. The sheet processing device <NUM> further includes separation members <NUM> between the winding roller <NUM> and the exit roller pair <NUM>. The separation members are movable in the width direction of the two-ply sheet S.

A sheet conveyance sensor C3 is disposed downstream from the entrance roller pair <NUM> in the sheet conveyance direction to detect the sheet conveyance position of the lamination sheet S and the sheet conveyance position of the inner sheet PM.

An abnormal condition detection sensor C4 is disposed downstream from the winding roller <NUM> in the sheet conveyance direction to detect the condition of the lamination sheet S.

A sheet conveyance sensor C5 is disposed downstream from the exit roller pair <NUM> in the sheet conveyance direction to detect the sheet conveyance position of the lamination sheet S.

Each of the pickup roller <NUM>, the conveyance roller pair <NUM>, the entrance roller pair <NUM>, and the winding roller <NUM> serves as a first sheet feeder, and each of the pickup roller <NUM>, the entrance roller pair <NUM>, and the winding roller <NUM> serves as a second sheet feeder.

An operation panel <NUM> is provided on the exterior of the sheet processing device <NUM>. The operation panel <NUM> serves as a display-operation device to display information of the sheet processing device <NUM> and receives input of the operation of the sheet processing device <NUM>. The operation panel <NUM> also serves as a notification device to output a perceptual signal to a user. As an alternative, a notification device other than the operation panel <NUM> may be separately provided in the sheet processing device <NUM>.

The sheet processing device <NUM> according to the present embodiment stacks lamination sheets S and inner sheets P on the sheet tray <NUM> and the sheet tray <NUM> separately. As a lamination sheet S is conveyed into the sheet processing device <NUM>, the sheet processing device <NUM> separates and opens the lamination sheet S into two sheets and inserts the inner sheet P into an opening of the lamination sheet S. The exit roller pair <NUM> ejects and stacks the lamination sheet S, in which the inner sheet P has been inserted, onto the sheet ejection tray <NUM>.

<FIG> is a diagram illustrating the main part of the sheet processing device <NUM> of <FIG>.

As illustrated in <FIG>, each of the entrance roller pair <NUM> and the exit roller pair <NUM> is, for example, two rollers paired with each other and driven by a driver such as a motor. Specifically, the entrance roller pair <NUM> is driven and rotated by an entrance roller pair motor 108a (see <FIG>), and the exit roller pair <NUM> is driven and rotated by an exit roller pair motor 113a (see <FIG>). The entrance roller pair <NUM> rotates in one direction. The exit roller pair <NUM> rotates in forward and reverse directions, thereby nipping and conveying the lamination sheet S and the inner sheet P.

The entrance roller pair <NUM> conveys the lamination sheet S and the inner sheet P toward the exit roller pair <NUM>.

The sheet conveyance direction indicated by arrow A in <FIG> is hereinafter referred to as a "forward conveyance direction" or a sheet conveyance direction A.

On the other hand, the exit roller pair <NUM> can switch the direction of rotation between the forward conveyance direction and a direction opposite to the forward conveyance direction. The exit roller pair <NUM> conveys the lamination sheet S nipped by the rollers of the exit roller pair <NUM> toward the sheet ejection tray <NUM> (see <FIG>) in the forward conveyance direction and also conveys the lamination sheet S toward the winding roller <NUM> in the direction opposite the forward conveyance direction (to convey the lamination sheet S in reverse). The sheet conveyance direction of the lamination sheet S toward the winding roller <NUM> (in other words, the direction opposite to the forward conveyance direction) indicated by arrow B in <FIG> is hereinafter referred to as a reverse conveyance direction or a sheet conveyance direction B.

The sheet processing device <NUM> further includes a sheet separation unit <NUM> between the entrance roller pair <NUM> and the exit roller pair <NUM>. The sheet separation unit <NUM> includes the winding roller <NUM> serving as a rotary member and the separation members <NUM>. The winding roller <NUM> is driven by a winding roller motor 109a (see <FIG>) to rotate in the forward and reverse conveyance directions. The direction of rotation of the winding roller <NUM> is switchable between the forward conveyance direction (clockwise direction) and the reverse conveyance direction (counterclockwise direction).

The winding roller <NUM> includes a roller <NUM> and a sheet gripper <NUM> movably disposed on the roller <NUM> to grip the sheet S. The sheet gripper <NUM> is driven by a sheet gripper motor 110a (see <FIG>) to be rotatable with the roller <NUM>. The sheet gripper <NUM> is movable and grips the leading end of the lamination sheet S with the roller <NUM>. In the present embodiment, the sheet gripper <NUM> and the roller <NUM> are separate units. However, the sheet gripper <NUM> may be formed on the outer circumference of the roller <NUM> as a single unit.

A description is given of a series of operations performed in the sheet processing device <NUM>, with reference to <FIG>.

The series of operations performed by the sheet processing device <NUM> indicates the operations from separating the lamination sheet S to inserting the inner sheet P into the lamination sheet S. In <FIG>, elements identical to those illustrated in <FIG> are given identical reference numerals, and the descriptions thereof are omitted.

<FIG> are diagrams, each illustrating the main part of the sheet processing device <NUM> in an operation subsequent to the operation of the previous drawing.

<FIG>, <FIG> are diagrams, each illustrating the sheet processing device <NUM> performing an operation in a single sheet insertion mode.

<FIG> are diagrams, each illustrating the sheet processing device <NUM> performing an operation in a multiple sheet insertion mode.

<FIG> is a diagram illustrating the main part of the sheet processing device <NUM>.

In <FIG>, the lamination sheet S is loaded on the sheet tray <NUM> such that a part of the bonded side (bonded portion r) of the lamination sheet S is located downstream from the pickup roller <NUM> in the sheet feed direction (sheet conveyance direction). In the sheet processing device <NUM>, the pickup roller <NUM> picks up the lamination sheet S from the sheet tray <NUM>, and the conveyance roller pair <NUM> conveys the lamination sheet S toward the entrance roller pair <NUM>.

As illustrated in <FIG>, the entrance roller pair <NUM> conveys the two-ply sheet S toward the winding roller <NUM>. In the sheet processing device <NUM>, the entrance roller pair <NUM> conveys the lamination sheet S with the bonded end, which is one of four sides of the lamination sheet S, as the downstream side in the forward conveyance direction A as indicated by arrow A in <FIG>.

Subsequently, as illustrated in <FIG>, the sheet processing device <NUM> temporarily stops conveyance of the lamination sheet S when the trailing end of the lamination sheet S in the forward conveyance direction has passed the winding roller <NUM>. These operations are performed by conveying the two-ply sheet S from the sheet conveyance sensor C3 by a designated amount in response to the timing at which the sheet conveyance sensor C3 detects the leading end of the two-ply sheet S.

As illustrated in <FIG>, the sheet processing device <NUM> causes the sheet gripper <NUM> to open and the exit roller pair <NUM> to rotate in the reverse direction to convey the lamination sheet S in the reverse conveyance direction (i.e., the reverse conveyance direction B in <FIG>) toward an opening portion of the sheet gripper <NUM>.

Subsequently, as illustrated in <FIG>, the sheet processing device <NUM> stops conveyance of the lamination sheet S when the trailing end of the lamination sheet S is inserted into the opening portion of the sheet gripper <NUM>, and causes the sheet gripper <NUM> to close and grip the trailing end of the lamination sheet S. These operations are performed when the lamination sheet S is conveyed by the designated amount.

Then, as illustrated in <FIG>, the sheet processing device <NUM> causes the driver to rotate the winding roller <NUM> in the counterclockwise direction in <FIG> to wind the lamination sheet S around the winding roller <NUM>. The lamination sheet S is wound around the winding roller <NUM> from the side where the two sheets of the lamination sheet S are overlapped but not bonded.

As illustrated in <FIG>, when the lamination sheet S is wound around the winding roller <NUM>, a winding circumferential length difference is created between the two sheets in the amount of winding of the lamination sheet S (i.e., two-ply sheet) around the circumference of the winding roller <NUM>. There is a surplus of the sheet on the inner circumferential side to the center of the winding roller <NUM>, which generates a slack toward the bonded end (i.e., the bonded portion r). As a result, a space g (slack) is created between the two sheets of the lamination sheet S. As the separation members <NUM> are inserted into the space g formed as described above, from opposed sides of the lamination sheet S, the space g between the two sheets is maintained. In response to the detection of the leading end of the lamination sheet S with the sheet conveyance sensor C5, the lamination sheet S is conveyed from the sheet conveyance sensor C5 by a designated amount to perform these operations.

A description is now given of the separation members <NUM>.

<FIG> is a schematic view of each separation member <NUM> included in the sheet processing device <NUM>.

<FIG> are schematic views, each illustrating an example of a drive configuration of the separation members <NUM>.

Further, <FIG> is a perspective view of a state in which the separation members <NUM> are inserted into the lamination sheet S.

As illustrated in <FIG>, when viewed from the upstream side in the sheet conveyance direction, the size in the height (vertical direction) of the separation member <NUM> gradually increases from the center in the width direction to the trailing end (right end in <FIG>). Further, when viewed from the vertical direction, the size of the separation member <NUM> in the sheet conveyance direction gradually increases from the leading end to the center. When viewed from the width direction of the lamination sheet S, each of the separation members <NUM> has a cross shape. Each separation member <NUM> further has a branching member that functions as a guide to guide the two sheets separated from the lamination sheet S in different directions due to the above-described cross shape.

Further, in the present embodiment, referring to <FIG>, the two separation members <NUM> are disposed facing each other and moved in the approaching direction and the separating direction, for example, by a belt drive mechanism as illustrated in <FIG> and by a rack and pinion mechanism illustrated in <FIG>.

More specifically, the belt drive mechanism illustrated in <FIG> includes a belt <NUM> stretched between a drive pulley 30a and a driven pulley 30b and the two separation members 116a and 116b are attached to the belt <NUM> while facing each other. The separation member 116a is attached and connected to the lower part of the belt <NUM> and the separation member 116b is attached and connected to the upper part of the belt <NUM>.

The drive pulley 30a is provided with a drive transmission gear <NUM>. The rotational output of a separation member motor <NUM> is transmitted to the drive transmission gear <NUM> via a motor output gear <NUM>. In other words, the rotational output of the separation member motor <NUM> is transmitted to the belt <NUM>.

As a result, as the separation member motor <NUM> is rotated in the clockwise direction (when viewed from the front of the drawing), the separation members 116a and 116b are moved toward each other. By contrast, as the separation member motor <NUM> is rotated in the counterclockwise direction (when viewed from the front of the drawing), the separation members 116a and 116b are moved away from each other.

The rack and pinion mechanism illustrated in <FIG> includes two racks 42a and 42b extending in opposite directions from each other. Each of the racks 42a and 42b meshes with a single pinion <NUM>. The separation member 116a that is attached to the rack 42a faces the separation member 116b that is attached to the rack 42b. The pinion <NUM> is provided with a drive transmission gear <NUM>. The rotational output of a separation member motor <NUM> is transmitted to the drive transmission gear <NUM> via a motor output gear <NUM>. The rotational output of the separation member motor <NUM> is transmitted to the racks 42a and 42b, respectively.

As described above, in the present embodiment, each of the separation members 116a and 116b has the above-mentioned shape and is movable in the width direction of the lamination sheet S. Accordingly, the separation members 116a and 116b are smoothly inserted into the space g created in the lamination sheet S as illustrated in <FIG>.

A description of a series of operations of the sheet processing device <NUM> is continued below.

With the separation members <NUM> inserted in the space g created in the lamination sheet S (see <FIG>), the sheet processing device <NUM> causes the winding roller <NUM> to rotate in the clockwise direction and shift the space g separating the two sheets of the lamination sheet S to the trailing end of the lamination sheet S in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>), as illustrated in <FIG>. After the winding roller <NUM> has been rotated by a designated amount, the sheet processing device <NUM> causes the sheet gripper <NUM> to open. As a result, the lamination sheet S is separated into the upper and lower sheets at the trailing end.

In this state, the sheet processing device <NUM> temporarily stops the conveyance of the lamination sheet S and further moves the separation members <NUM> in the width direction of the lamination sheet S to separate the whole area of the trailing end of the lamination sheet S. In response to the detection of the leading end of the lamination sheet S with the sheet conveyance sensor C5, the lamination sheet S is conveyed from the sheet conveyance sensor C5 by a designated amount to perform these operations.

<FIG> is a perspective view of the separation members <NUM> and the lamination sheet S in the state illustrated in <FIG>.

<FIG> is another perspective view of each separation member <NUM> and the lamination sheet S in the state illustrated in <FIG>, performing an operation subsequent to the operation in <FIG>.

Since each of the separation members <NUM> further has a branching guide that functions as a guide to guide the two sheets separated from the lamination sheet S in different directions due to the above-described shape (see the cross shape illustrated in <FIG>), the two sheets separated from the lamination sheet S may be kept in postures to be conveyed to different sheet conveyance passages.

Further, since the separation members <NUM> are movable in the width direction of the lamination sheet S (see <FIG>), the separation members <NUM> are positioned suitably to support the postures of the two sheets of the lamination sheet S as illustrated in <FIG>. Due to such a configuration, even when the size of the lamination sheet S and the rigidity (or retentivity corresponding to the propensity to retain a particular shape once applied, such as curvature of paper) of the lamination sheet S change, the two sheets separated from the lamination sheet S are guided in desired branching directions. This configuration eliminates the need for a branching member to branch the lamination sheet S over the whole area of the sheet lamination sheet S in the width direction and a driver to drive the branching member, thereby reducing the cost when compared with the configuration of a typical sheet processing device.

Subsequently, as illustrated in <FIG>, after the separation members <NUM> have separated the whole area of the trailing end of the two-ply sheet S, the sheet processing device <NUM> causes the driver to rotate the exit roller pair <NUM> in the counterclockwise direction in <FIG> to convey the two-ply sheet S in the reverse conveyance direction (i.e., the reverse conveyance direction B in <FIG>). In other words, the separation members <NUM> guide the two sheets separated from the lamination sheet S in the upper and lower directions (vertically), respectively, and thus the two sheets are fully separated.

The sheet processing device <NUM> temporarily stops the conveyance of the lamination sheet S, so that a bonded portion r of the lamination sheet S is gripped (nipped) by the exit roller pair <NUM>. Accordingly, one end of the lamination sheet S is bonded as the bonded side of the lamination sheet S and the other end of the lamination sheet S is opened largely.

In response to the detection of the leading end of the lamination sheet S with the sheet conveyance sensor C5, the lamination sheet S is conveyed from the sheet conveyance sensor C5 by a designated amount to perform these operations.

A description is now given of the operation of inserting an inner sheet into the separated lamination sheet S.

The sheet processing device <NUM> according to the present embodiment can insert one to a plurality of inner sheets P into a lamination sheet S depending on the size of the lamination sheet S (i.e., the length of the lamination sheet S in the sheet conveyance direction) and the size of the inner sheet P (i.e., the length of the inner sheet P in the sheet conveyance direction).

Firstly, a description is given of a single sheet insertion mode to insert a single inner sheet P into a lamination sheet S, with reference to <FIG>. Then, a description is given of a multiple sheet insertion mode to insert multiple inner sheets P into a lamination sheet S along the sheet conveyance direction, with reference to <FIG>.

As illustrated in <FIG>, the sheet processing device <NUM> causes the entrance roller pair <NUM> to rotate to convey the inner sheet P conveyed from the sheet tray <NUM> (see <FIG>) via a sheet conveyance roller pair <NUM> toward the exit roller pair <NUM> in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>).

Subsequently, as illustrated in <FIG>, the sheet processing device <NUM> causes the exit roller pair <NUM> to rotate so that the lamination sheet S and the inner sheet P meet to insert the inner sheet P into the lamination sheet S from the open portion (on the other end) of the lamination sheet S.

Then, as illustrated in <FIG>, the exit roller pair <NUM> of the sheet processing device <NUM> conveys the lamination sheet S in which the inner sheet P is inserted, in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>). Thus, the two sheets of the lamination sheet S are overlapped one on another again so as to close the open portion of the lamination sheet S. Then, the lamination sheets S with the inner sheet P being inserted are ejected by the exit roller pair <NUM> or the ejection roller pair <NUM> (see <FIG>) disposed downstream from the exit roller pair <NUM> and are stacked on the sheet ejection tray <NUM> (see <FIG>).

Then, a description is given of the multiple sheet insertion mode. In the multiple sheet insertion mode, a plurality of inner sheets P (two sheets in the embodiment) are insertable a single lamination sheet S in the sheet conveyance direction.

Then, as illustrated in <FIG>, the sheet processing device <NUM> causes the entrance roller pair <NUM> to rotate to convey a first inner sheet P (hereinafter, referred to as a first inner sheet P1) conveyed from the sheet tray <NUM> (see <FIG>) via a sheet conveyance roller pair <NUM> toward the exit roller pair <NUM> in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>).

Subsequently, as illustrated in <FIG>, the sheet processing device <NUM> causes the exit roller pair <NUM> to rotate so that the lamination sheet S and the first inner sheet P1 meet. By so doing, the first inner sheet P1 is inserted into the opening of the lamination sheet S. At this time, the sheet processing device <NUM> conveys a second inner sheet P (hereinafter, referred to as a second inner sheet P2) conveyed from the sheet tray <NUM> (see <FIG>) toward the exit roller pair <NUM> in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>).

Subsequently, as illustrated in <FIG>, the sheet processing device <NUM> causes the entrance roller pair <NUM> to rotate so that the lamination sheet S and the second insertion sheet P2 meet. By so doing, the second inner sheet P2 is inserted into the opening of the lamination sheet S.

As illustrated in <FIG>, the sheet processing device <NUM> causes the exit roller pair <NUM> to convey the lamination sheet S, with the first inner sheet P1 and the second inner sheet P2 being inserted, in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>). By so doing, the two sheets are overlaid one on another again to close the opening.

Even if there are three or more inner sheets P, the three or more inner sheets P can be inserted in the lamination sheet S by repeating the above-described operations.

As an alternative example, in a case where a sheet processing device includes a thermal-pressure device (see a thermal fixing roller pair <NUM> in <FIG>) that can heat and press the lamination sheet S, a branching member <NUM> may change (switch) the sheet conveyance passage of the lamination sheet S to convey the lamination sheet S to the thermal-pressure device, as illustrated in <FIG>. Not only in the multiple sheet insertion mode but also in the single sheet insertion mode, the sheet conveyance passage may be changed (switched) with the branching member <NUM>.

As described above, the sheet processing device <NUM> according to the present embodiment can control the driver and other parts to perform the sheet inserting operation of an inner sheet P or inner sheets P to be inserted into a lamination sheet S.

A description is now given of a configuration in which the sheet processing device <NUM> acquires the size of the lamination sheet S (i.e., the length in the sheet conveyance direction of the lamination sheet S), the size of the inner sheet P (i.e., the length in the sheet conveyance direction of the inner sheet P), and the number of the inner sheets P to be inserted into the lamination sheet S.

As illustrated in <FIG>, the sheet processing device <NUM> according to the present embodiment includes the sheet size sensor C6 serving as a sheet size detector and the sheet size sensor C7 serving as a medium size detector.

Based on the detection results of the sheet size sensors C6 and C7, the sheet processing device <NUM> determines whether the length of the inner sheet P in the sheet conveyance direction is equal to or smaller than the threshold value. When the length of the inner sheet P in the sheet conveyance direction is equal to or smaller than the threshold value, the sheet processing device <NUM> automatically switches to the multiple sheet insertion mode to perform the sheet inserting operation. On the other hand, when the length of the inner sheet P in the sheet conveyance direction is greater than the threshold value, the sheet processing device <NUM> automatically switches to the single sheet insertion mode to perform the sheet inserting operation.

In particular, when the length of the inner sheet P in the sheet conveyance direction is equal to or smaller than half the length of the lamination sheet S in the sheet conveyance direction, the sheet processing device <NUM> may automatically switch to the multiple sheet insertion mode to perform the sheet inserting operation. In the multiple sheet insertion mode, the sheet processing device <NUM> determines the number of inner sheets P to be inserted into the lamination sheet S from the quotient of the size of the lamination sheet S divided by the size of inner sheet P.

Instead of or in addition to the detection results of the sheet size sensors C6 and C7, the sheet processing device <NUM> may use the detection results of the sheet conveyance sensors C1 and C2.

As described above, the sheet processing device <NUM> according to the present embodiment can automatically control the sheet inserting operation according to the size of the lamination sheet S and the size of the inner sheet P.

Additionally, as illustrated in <FIG>, the sheet processing device <NUM> according to the present embodiment can separately stack the lamination sheets S and the inner sheets P on separate trays to be conveyed separately. Accordingly, there is no need to stack the lamination sheets S and the inner sheets P in a predetermined order, and this configuration can enhance the convenience. In the present embodiment, the lamination sheets S are stacked on the sheet tray <NUM> and the inner sheets P are stacked on the sheet tray <NUM>. However, the tray on which the lamination sheets S are stacked and the tray on which the inner sheets P are stacked are not limited to the above-described trays. For example, the inner sheets P may be stacked on the sheet tray <NUM> and the lamination sheets S may be loaded on the sheet tray <NUM>.

A description is now given of the sheet processing device having another example of a sheet guide passage of the two sheets separated from the lamination sheet S, with reference to <FIG>.

<FIG> are schematic views, each illustrating a sheet guide passage of the two sheets separated from the lamination sheet S, according to a modification of the present disclosure.

Specifically, <FIG> illustrates a case where the two separated sheets are guided from the bonded portion r of the lamination sheet S in the direction opposite to the sheet conveyance direction (i.e., the direction indicated by arrow B in <FIG>) as illustrated in <FIG>. Alternatively, as illustrated in <FIG>, the upper sheet of the separated lamination sheet S may be guided from the bonded portion r in the sheet conveyance direction (i.e., the direction indicated by arrow A in <FIG>) and the lower sheet of the separated lamination sheet S may be guided from the bonded portion r in the direction opposite to the sheet conveyance direction. Further, as illustrated in <FIG>, the upper sheet of the separated lamination sheet S may be guided from the bonding portion r in the direction opposite to the sheet conveyance direction and the lower sheet of the separated lamination sheet S may be guided from the bonded portion r in the sheet conveyance direction. As illustrated in FIG. 9A, the two sheets separated from each other from the lamination sheet S are branched by the separation members <NUM> and then guided in the direction opposite to the sheet conveyance direction. However, the two sheets separated from each other from the lamination sheet S may be branched by the separation members <NUM> and then guided in the sheet conveyance direction.

A description is then given of a sheet laminator including the sheet processing device, an image forming apparatus including the sheet laminator, and an image forming system including the sheet laminator, according to an embodiment of the present disclosure.

<FIG> is a diagram illustrating an overall configuration of a sheet laminator according to an embodiment of the present disclosure, including the sheet processing device.

As illustrated in <FIG>, a sheet laminator <NUM> includes the sheet processing device <NUM> described above, a branching member <NUM>, a thermal fixing roller pair <NUM>, and an ejection roller pair <NUM>. The branching member <NUM> changes (switches) the sheet conveyance passage of the lamination sheet S. The thermal fixing roller pair <NUM> that function as a pair of thermal fixing rollers that can heat and press the lamination sheet S. The ejection roller pair <NUM> is disposed downstream from the thermal fixing roller pair <NUM> in the sheet conveyance direction.

The sheet laminator <NUM> performs a series of operations, in this order, of feeding the lamination sheet S, separating the lamination sheet S, inserting the inner sheet P into the lamination sheet S, and laminating the lamination sheet S with the inner sheet P being inserted, by application of heat and pressure, on a stand-alone basis. This series of operations is carried out automatically without any aid of a user. For this reason, the sheet laminator <NUM> can enhance and provide the convenience better than a known sheet laminator employing a known technique.

<FIG> is a diagram illustrating an overall configuration of an image forming system according to an embodiment of the present disclosure, including the sheet laminator and an image forming apparatus.

An image forming system <NUM> includes a sheet laminator 200a in an in-body sheet discharging section of an image forming apparatus <NUM>. The sheet laminator 200a functions as a device that performs sheet lamination.

The sheet laminator 200a includes the sheet tray <NUM> on which the lamination sheets S or the inner sheets P are stacked. The sheet laminator 200a can receive the lamination sheets S, the inner sheets PM, or both from the image forming apparatus <NUM>. Accordingly, the image forming apparatus <NUM> (e.g., a printer and a copier) can form an image on the lamination sheet S or the inner sheet P by the in-line connection.

A detailed description is given of the configuration of the image forming apparatus <NUM>.

As illustrated in <FIG>, the image forming apparatus <NUM> includes an intermediate transfer device <NUM>. The intermediate transfer device <NUM> includes an intermediate transfer belt <NUM> having an endless loop and being entrained around a plurality of rollers and stretched substantially horizontally. The intermediate transfer belt <NUM> rotates in the counterclockwise direction in <FIG>.

The image forming apparatus <NUM> further includes image forming units 154c, <NUM>, 154y, and <NUM> for cyan (C), magenta (M), yellow (Y), and black (K), respectively. The image forming units 154c, <NUM>, 154y, and <NUM> are disposed below the intermediate transfer device <NUM> in the housing 300a. The image forming units 154c, <NUM>, 154y, and <NUM> are aligned in a quadruple tandem manner along an extended direction of the intermediate transfer belt <NUM>. Each of the image forming units 154c, <NUM>, 154y, and <NUM> includes a drumshaped image bearer that rotates in the clockwise direction in <FIG>. Various image forming components, for example, a charging unit, a developing unit, a transfer unit, and a cleaning unit, are disposed around each of the image forming units 154c, <NUM>, 154y, and <NUM>. An exposure device <NUM> is disposed below the image forming units 154c, <NUM>, 154y, and <NUM> included in the image forming apparatus <NUM>.

A sheet feeder <NUM> is disposed below the exposure device <NUM> in the image forming apparatus <NUM>. The sheet feeder <NUM> includes a first sheet tray <NUM> that stores lamination sheets S and a second sheet tray <NUM> that stores inner sheets P. The first sheet tray <NUM> serves as a third sheet stacker on which a two-ply sheet such as the lamination sheet S is stacked. Similarly, the second sheet tray <NUM> serves as a fourth sheet stacker on which a sheet medium (e.g., the inner sheet P) is stacked.

A first feed roller <NUM> is disposed at a position upper right of the first sheet tray <NUM>. The first feed roller <NUM> feeds out the lamination sheet S one by one from the first sheet tray <NUM> to a sheet conveyance passage <NUM>. A second feed roller <NUM> is disposed at the upper right of the second sheet tray <NUM> and feeds the inner sheet P from the second sheet tray <NUM> one by one to the sheet conveyance passage <NUM>.

The sheet conveyance passage <NUM> extends upwardly from the lower side to the upper side on the right side in the image forming apparatus <NUM> and communicates with the sheet laminator 200a in the image forming apparatus <NUM>. The sheet conveyance passage <NUM> is provided with, e.g., a conveyance roller pair <NUM>, a secondary transfer device <NUM> in contact with the intermediate transfer belt <NUM>, a fixing device <NUM>, and a first sheet ejection device <NUM> including the ejection roller pair, serially.

The first feed roller <NUM>, the conveyance roller pair <NUM>, and the sheet conveyance passage <NUM> serve as a third sheet feeder to feed the two-ply sheet (i.e., the lamination sheet S) from the first sheet tray <NUM> (serving as a third sheet stacker). The second feed roller <NUM>, the conveyance roller pair <NUM>, and the sheet conveyance passage <NUM> serve as a fourth sheet feeder to feed the sheet medium (i.e., the inner sheet P) from the second sheet tray <NUM> (serving as a fourth sheet stacker). Further, the intermediate transfer device <NUM> and the fixing device <NUM> serve as a part of the image forming device that forms an image on a sheet medium (i.e., the inner sheet P).

A description is now given of operations of the image forming apparatus <NUM> according to the present embodiment, to form an image on a sheet medium (i.e., the inner sheet P) and then perform a sheet laminating operation on the lamination sheet S.

To perform an image on the sheet medium (i.e., the inner sheet P), first, an image reading device <NUM> reads the image on an original document, and the exposure device <NUM> then performs writing of the image on the original document. The image forming units 154c, <NUM>, 154y, and <NUM> form respective toner images of cyan (C), magenta (M), yellow (Y), and black (K), respectively, on the respective image bearers. Then, primary transfer devices 180c, <NUM>, 180y, and <NUM> sequentially transfer the respective toner images onto the intermediate transfer belt <NUM>, thereby forming a color image on the intermediate transfer belt <NUM>.

By contrast, the image forming apparatus <NUM> rotates the second feed roller <NUM> to feed and convey the inner sheet P to the sheet conveyance passage <NUM>. The inner sheet P is conveyed by the conveyance roller pair <NUM> through the sheet conveyance passage <NUM> and is sent to the secondary transfer device <NUM> in synchrony with movement of the color image on the intermediate transfer belt <NUM>. Then, the secondary transfer device <NUM> transfers the color image formed on the intermediate transfer belt <NUM> as described above, onto the inner sheet P.

After the color image has been transferred onto the inner sheet P, the fixing device <NUM> fixes the color image to the inner sheet P, and the first sheet ejection device <NUM> ejects to convey the inner sheet P to the sheet laminator 200a.

The sheet laminator 200a rotates the pickup roller <NUM> to pick up the lamination sheet S from the sheet tray <NUM> on which the lamination sheet S is stacked and conveys the lamination sheet S to the sheet separation unit <NUM> (including the winding roller <NUM> and the separation members <NUM>). The sheet separation unit <NUM> separates a lamination sheet S into two sheets and conveys an inner sheet P conveyed from the image forming apparatus <NUM> by the entrance roller pair <NUM>. By so doing, the inner sheet P is inserted between the separated two sheets of the lamination sheet S. Then, the lamination sheet S with the inner sheet P being inserted is conveyed by the exit roller pair <NUM> to a thermal fixing unit <NUM> as a thermal fixer. Then, the thermal fixing roller pair <NUM> of the thermal fixing unit <NUM> applies heat and pressure to the lamination sheet S in which the inner sheet P is inserted, in other words, the thermal fixing roller pair <NUM> of the thermal fixing unit <NUM> performs a sheet laminating operation on the lamination sheet S with the inner sheet P being inserted.

As described above, the lamination sheet S and the inner sheet P on which an on which an image is formed are conveyed to the sheet laminator 200a to receive the sheet laminating operation performed by the sheet laminator 200a.

According to the above-described configuration of the image forming system <NUM> according to the present embodiment, the lamination sheet S stacked on the first sheet tray <NUM> of the image forming apparatus <NUM> is conveyed to the sheet laminator 200a via the sheet conveyance passage <NUM> and separate the lamination sheet S into two sheets in the sheet separation unit <NUM>. Then, while the sheet laminator 200a performs a sheet separating operation on the lamination sheet S, the image forming apparatus <NUM> conveys the inner sheet P stacked on the second sheet tray <NUM> in the sheet conveyance passage <NUM>, the secondary transfer device <NUM>, the fixing device <NUM>, and the first sheet ejection device <NUM> to form an image on the inner sheet P, and then conveyed the inner sheet P to the sheet laminator 200a. Then, the sheet laminator 200a may also perform the sheet laminating operation on the lamination sheet S after inserting the inner sheet P on which an image is formed into the lamination sheet S separated into two sheets.

Descriptions are then given of an image forming system including the sheet processing device according to an embodiment of the present disclosure and an image forming apparatus, according to a modification of the above-described embodiment.

<FIG> is a diagram illustrating an overall configuration of an image forming system according to a modification of the present disclosure, including the sheet laminator and an image forming apparatus.

In an image forming system <NUM> illustrated in <FIG>, an image forming apparatus <NUM> is basically the same as the image forming apparatus <NUM> illustrated in <FIG>. However, different from the image forming apparatus <NUM>, the image forming apparatus <NUM> includes a second sheet ejection device <NUM> and a sheet ejection tray <NUM>.

When the sheet laminating operation is not performed, the image forming apparatus <NUM> may form an image on the inner sheet P fed from the second sheet tray <NUM>, and then eject the inner sheet P having the image by the second sheet ejection device <NUM> including a pair of sheet ejection rollers to the sheet ejection tray <NUM>. Accordingly, when the sheet laminating operation is not performed, the image forming apparatus <NUM> does not need to decrease the output speed of image formation. For this reason, the image forming apparatus <NUM> can maintain the image formation productivity.

The image forming apparatus <NUM> may include the sheet laminator 200a detachably attached to the in-body sheet discharging section. In other words, when the sheet laminating operation is not performed, the sheet laminator 200a may be detached from the image forming apparatus <NUM>.

In addition, the sheet laminator 200a thus detached from the image forming apparatus <NUM> may include the sheet tray <NUM> to stack the inner sheets P and the pickup roller <NUM> to feed the inner sheet P from the sheet tray <NUM>, so that the sheet laminator 200a can be used as a single unit such as the sheet laminator <NUM> illustrated in <FIG>.

The image forming system <NUM> illustrated in <FIG> and the image forming system <NUM> illustrated in <FIG> may include the sheet processing device <NUM> in an in-body sheet discharging section instead of including the sheet laminator 200a. The image forming system <NUM> illustrated in <FIG> may include the sheet processing device <NUM> detachably attachable to the image forming system <NUM>.

Each of the image forming system <NUM> illustrated in <FIG> and the image forming system <NUM> illustrated in <FIG> may include a large-capacity sheet ejection device (stacker), a post-processing apparatus such as a binder unit, or both.

In a case where the lamination sheet S that is stacked on the first sheet tray <NUM> included in the image forming apparatus <NUM> illustrated in <FIG> or the image forming apparatus <NUM> illustrated in <FIG> passes through the fixing device <NUM>, the lamination sheet S is not bonded at the fixing temperature but is bonded by application of heat higher than the fixing temperature. Although the image forming apparatus <NUM> illustrated in <FIG> and the image forming apparatus <NUM> illustrated in <FIG> employ electrophotography for image formation on the inner sheet P in the description above, the image formation method is not limited to the above-described configuration. For example, inkjet, stencil printing, or other known printing method may be employed to the image forming apparatuses <NUM> and <NUM>.

<FIG> is a diagram illustrating an overall configuration of an image forming system including the sheet laminator according to an embodiment of the present disclosure, outside an image forming apparatus.

<FIG> is a diagram illustrating an overall configuration of another image forming system including the sheet laminator according to an embodiment of the present disclosure, outside an image forming apparatus.

In <FIG> and <FIG>, elements identical to the elements illustrated in <FIG> and <FIG> are given identical reference numerals, and the descriptions these elements are omitted.

As illustrated in <FIG>, an image forming system <NUM> is basically same as the image forming system <NUM> illustrated in <FIG> and the image forming system <NUM> illustrated in <FIG>. However, different from the image forming systems <NUM> and <NUM>, the image forming system <NUM> illustrated in <FIG> includes a sheet laminator 200b on the outside of an image forming apparatus <NUM>.

The sheet laminator 200b includes the sheet tray <NUM> on which the lamination sheets S are stacked and has the configuration in which an inner sheet P can be fed from the image forming apparatus <NUM> via a relay conveyance device R. The sheet laminator 200b further includes the conveyance sensor C2 disposed downstream from an entrance roller pair <NUM> and upstream from an exit roller pair <NUM> in the sheet conveyance direction. The sheet laminator 200b further includes a first conveyance roller pair <NUM> disposed upstream from the thermal fixing roller pair <NUM> and a second conveyance roller pair <NUM> disposed downstream from the thermal fixing roller pair <NUM> in the sheet conveyance direction. Due to such a configuration, the image forming system <NUM> can automatically perform any image forming operation on an inner sheet P with a copier or a printer (i.e., the image forming apparatus <NUM>), a sheet separating operation on a lamination sheet S, a sheet inserting operation on the inner sheet P having an image into the separated lamination sheet S, and a sheet laminating operation on the lamination sheet S in which the inner sheet P is inserted.

The image forming system <NUM> illustrated in <FIG> has a configuration in which another post-processing apparatus <NUM> is disposed further downstream from the sheet laminator 200b in the sheet conveyance direction of the lamination sheet S. This post-processing apparatus <NUM> includes, for example, a large-capacity sheet ejection device (stacker), a post-processing apparatus such as a binder, or both. According to the request of a user, the job performing the sheet laminating operation and the job not performing the sheet laminating operation can be performed in parallel, which can enhance the working efficiency.

<FIG> is a block diagram illustrating a hardware configuration of a control block of the sheet laminator <NUM> to control the operation performed in the sheet laminator <NUM>.

As illustrated in <FIG>, the sheet laminator <NUM> includes a central processing unit (CPU) <NUM>, a random access memory (RAM) <NUM>, a read only memory (ROM) <NUM>, a hard disk drive (HDD) <NUM>, and an interface (I/F) <NUM>. The CPU <NUM>, the RAM <NUM>, the ROM <NUM>, the HDD <NUM>, and the I/F <NUM> are connected to each other.

The CPU <NUM> is an arithmetic unit and controls the overall operations of the sheet laminator <NUM>.

The RAM <NUM> is a volatile storage medium that allows data to be read and written at high speed. The CPU <NUM> uses the RAM <NUM> as a work area for data processing.

The ROM <NUM> is a read-only non-volatile storage medium that stores programs such as firmware.

The HDD <NUM> is a non-volatile storage medium that allows data to be read and written and has a relatively large storage capacity. The HDD <NUM> stores, e.g., an operating system (OS), various control programs, and application programs.

The sheet laminator <NUM> processes, by an arithmetic function of the CPU <NUM>, e.g., a control program stored in the ROM <NUM> and an information processing program (or application program) loaded into the RAM <NUM>. Such processing configures a software controller including various functional modules of the sheet laminator <NUM>. The software controller thus configured cooperates with hardware resources of the sheet laminator <NUM> to construct functional blocks to implement functions of the sheet laminator <NUM>. In other words, the CPU <NUM>, the RAM <NUM>, the ROM <NUM>, and the HDD <NUM> implement a controller <NUM> to control the operation performed in the sheet laminator <NUM>.

The I/F <NUM> is an interface that connects a pickup roller motor 105a, a pickup roller motor 106a, a conveyance roller pair motor 107a, the entrance roller pair motor 108a, the exit roller pair motor 113a, an ejection roller pair motor 121a, the winding roller motor 109a, the sheet gripper motor 110a, the separation member motor <NUM> (<NUM>), a branching member motor 118a, a thermal fixing roller motor 129a, a heater <NUM> including a first heater 54a and a second heater 54b, and a cam drive motor <NUM>, to the controller <NUM>. Further, the I/F <NUM> is an interface that connects the size detection sensors C6 and C7, the sheet conveyance sensors C1, C2, C3, and C5, the abnormal condition detection sensor C4, a first thermistor 56a, a second thermistor 56b, and the operation panel <NUM>, to the controller <NUM>.

The controller <NUM> controls the operations of the pickup roller motors 105a and 106a, the conveyance roller pair motor 107a, the entrance roller pair motor 108a, the exit roller pair motor 113a, the ejection roller pair motor 121a, the winding roller motor 109a, the sheet gripper motor 110a, the separation member motor <NUM> (<NUM>), the branching member motor 118a, the thermal fixing roller motor 129a, the heater <NUM> including the first heater 54a and the second heater 54b, and a cam drive motor <NUM>, via the I/F <NUM>. Further, the controller <NUM> acquires the detection results from the size detection sensors C6 and C7, the sheet conveyance sensors C1, C2, C3, and C5, the abnormal condition detection sensor C4, the first thermistor 56a, and the second thermistor 56b.

The winding roller motor 109a is a driver to drive the winding roller <NUM> in the forward and reverse directions. The sheet gripper motor 110a is a driver to rotate the sheet gripper <NUM>. The separation member motor <NUM> (<NUM>) is a driver to move the separation members <NUM> in the width direction of the lamination sheet S. The branching member motor 118a is a driver to switch the position of the branching member <NUM>.

<FIG> including <FIG>, <FIG>, and <FIG> is a flowchart of a series of operations performed by the image forming system <NUM> illustrated in <FIG>, from feeding a lamination sheet S, inserting an inner sheet P, and completing lamination of the lamination sheet S with the inner sheet P being inserted.

A description is given of the series of operations, with reference to the reference numerals indicated in the flowchart of <FIG> including <FIG>, <FIG>, and <FIG>.

In the following description, only the sheet laminating operation in the image forming system <NUM> illustrated in <FIG> is described. However, the sheet laminating operations in the image forming system <NUM> illustrated in <FIG>, the image forming system <NUM> illustrated in <FIG>, and the image forming system <NUM> illustrated in <FIG> are similar to the image forming system <NUM> illustrated in <FIG>, and thus the detailed description is omitted.

First, in step S01, the image forming system <NUM> determines whether a user has selected the multiple sheet insertion mode. When the user has selected the multiple sheet insertion mode (YES in step S01), the image forming system <NUM> requests the user inputting the number of inner sheets in step S02. The number of inner sheets can be set by the user with, for example, the operation panel <NUM>.

On the other hand, when the user has not selected the multiple sheet insertion mode (NO in step S01), the image forming system <NUM> determines whether the user has selected the single sheet insertion mode with one inner sheet in step S03.

Subsequent to step S02 or step S03, the sheet laminator 200a starts feeding a lamination sheet S (see <FIG>), in step S11. Then, in step S12, the sheet laminator 200a determines whether the leading end of the lamination sheet S has reached the sheet conveyance sensor C3 (see <FIG>). In step S13, the sheet laminator 200a determines whether the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C3, and temporarily stops the conveyance (see <FIG>). When the lamination sheet S has not been conveyed by the specified amount from the sheet conveyance sensor C3 (NO in step S13), step S13 is repeated until the lamination sheet S is conveyed by the specified amount from the sheet conveyance sensor C3. On the other hand, when the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C3 (YES in step S13), the sheet laminator 200a causes the sheet gripper motor 110a to open the sheet gripper <NUM> in step S14, and conveys the lamination sheet S in the reverse conveyance direction (i.e., the direction indicated by arrow B in <FIG>) in step S15 (see <FIG>).

Then, the sheet laminator 200a determines whether the lamination sheet S has been conveyed by the specified amount in step S16. When the lamination sheet S has not been conveyed by the specified amount (NO in step S16), step S16 is repeated until the lamination sheet S is conveyed by the specified amount. On the other hand, when the lamination sheet S has been conveyed by the specified amount (YES in step S16), the sheet laminator 200a temporarily stops the conveyance in step S17. Then, in step S18, the sheet laminator 200a causes the sheet gripper motor 110a to close the sheet gripper <NUM> to nip the end of the lamination sheet S (see <FIG>).

Then, in step S19, the sheet laminator 200a causes the winding roller motor 109a to rotate the winding roller <NUM> in the counterclockwise direction, so that the lamination sheet S is would around the winding roller <NUM> (see <FIG>). In step S20, the sheet laminator 200a determines whether the leading end of the lamination sheet S has reached at the sheet conveyance sensor C5. When the leading end of the lamination sheet S has not reached the sheet conveyance sensor C5 (NO in step S20), step S20 is repeated until the leading end of the lamination sheet S reaches the sheet conveyance sensor C5. By contrast, when the leading end of the lamination sheet S has reached the sheet conveyance sensor C5 (YES in step S20), the sheet laminator 200a then executes the operation of step S21. In step S21, the sheet laminator 200a determines whether the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C5. When the lamination sheet S has not been conveyed by the specified amount from the sheet conveyance sensor C5 (NO in step S21), step S21 is repeated until the lamination sheet S is conveyed by the specified amount from the sheet conveyance sensor C5. By contrast, when the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C5 (YES in step S21), the sheet laminator 200a detects the condition of the lamination sheet S with the abnormal condition detection sensor C4 in step S22.

The abnormal condition detection sensor C4 is an abnormal condition detector that detects whether the dimension of the space g created between the two sheets of the lamination sheet S (the amount of bending of one of the two sheets) exceeds the predetermined threshold. In step S23, the sheet laminator 200a determines whether the lamination sheet S is in a normal condition, in other words, the size of the space g is equal to or greater than the given threshold, from the detection result of the abnormal condition detection sensor C4. When the sheet laminator 200a determines that the lamination sheet S is in a normal condition (i.e., the size of the space g is equal to or greater than the given threshold) from the detection result of the abnormal condition detection sensor C4 (YES in step S23), the sheet laminator 200a then executes the operation of step S24a.

On the other hand, when the sheet laminator 200a determines that the lamination sheet S is in an abnormal condition (i.e., the size of the space g is smaller than the given threshold) from the detection result of the abnormal condition detection sensor C4 (NO in step S23), the sheet laminator 200a notifies the user of the abnormal condition and stops the sheet processing operation in step S24b.

In step S24a, the sheet laminator 200a conveys the lamination sheet S by the specified amount in a direction opposite to the sheet winding direction (i.e., the direction indicated by arrow A in <FIG>), so that the bonded portion r of the lamination sheet S is located downstream from the nip region of the exit roller pair <NUM>. Accordingly, the space g created between the two sheets of the lamination sheet S can be formed at a position corresponding to the insertion position of the separation members <NUM>.

After step S24a, the sheet laminator 200a executes the operation of step S24c. In step S24c, the sheet laminator 200a causes the separation member motor <NUM> to inserts the separation members <NUM> from both sides of the lamination sheet S into the space g created between the two sheets of the lamination sheet S (see <FIG> and <FIG>). Then, in step S25, the sheet laminator 200a causes the winding roller motor 109a to rotate the winding roller <NUM> in the clockwise direction with the separation members <NUM> inserted from both sides of the lamination sheet S, and convey the lamination sheet S in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>).

Then, in step S26, the sheet laminator 200a determines whether the leading end of the lamination sheet S has reached the sheet conveyance sensor C5. When the leading end of the lamination sheet S has not reached the sheet conveyance sensor C5 (NO in step S26), step S26 is repeated until the leading end of the lamination sheet S reaches the sheet conveyance sensor C5. By contrast, when the leading end of lamination sheet S has reached the sheet conveyance sensor C5 (YES in step S26), the sheet laminator 200a executes the operation of step S27. In step S27, the sheet laminator 200a determines whether the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C5. When the lamination sheet S has not been conveyed by the specified amount from the sheet conveyance sensor C5 (NO in step S27), step S27 is repeated until the lamination sheet S is conveyed by the specified amount from the sheet conveyance sensor C5. By contrast, when the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C5 (YES in step S27), the sheet laminator 200a causes the sheet gripper motor 110a to open the sheet gripper <NUM> in step S28.

In step S29, the sheet laminator 200a conveys the lamination sheet S by the specified amount, then temporarily stops the conveyance of the lamination sheet S. Then, in step S30, the sheet laminator 200a causes the separation member motor <NUM> to further move the separation members <NUM> in the sheet width direction of the lamination sheet S (see <FIG> and <FIG>). As a result, the trailing ends of the two sheets of the lamination sheet S are separated into the upper and lower sheets.

In step S31, the sheet laminator 200a conveys the lamination sheet S in the reverse conveyance direction (i.e., the direction indicated by arrow B in <FIG>). Then, in step S32, the sheet laminator 200a determines whether the leading end of the lamination sheet S in the forward conveyance direction has reached the sheet conveyance sensor C5. When the leading end of the lamination sheet S has not reached the sheet conveyance sensor C5 (NO in step S32), step S32 is repeated until the leading end of the lamination sheet S reaches the sheet conveyance sensor C5. By contrast, when the leading end of lamination sheet S has reached the sheet conveyance sensor C5 (YES in step S32), the sheet laminator 200a then executes the operation of step S33. In step S33, the sheet laminator 200a determines whether the lamination sheet S has been conveyed by a specified amount from the sheet conveyance sensor C5. When the lamination sheet S has not been conveyed by the specified amount from the sheet conveyance sensor C5 (NO in step S33), step S33 is repeated until the lamination sheet S is conveyed by the specified amount from the sheet conveyance sensor C5. By contrast, when the lamination sheet S has been conveyed by the specified amount from the sheet conveyance sensor C5 (YES in step S33), the sheet laminator 200a temporarily stops the conveyance of the lamination sheet S in step S34 (see <FIG>). As a result, the separation of the lamination sheet S is completed.

Subsequently, in step S35, the sheet laminator 200a determines whether or not to perform the image forming operation (with an inline image forming apparatus) on the inner sheet P to be inserted into the lamination sheet S. When the image forming operation is performed with an inline image forming apparatus (YES in step S35), the sheet laminator 200a sends a signal to notify the inline image forming apparatus, for example, the image forming apparatus <NUM> (or the image forming apparatus <NUM> or the image forming apparatus <NUM>) to start the print job (printing operation) to form an image on the inner sheet P in step S36. Then, the sheet laminator 200a executes the operation of step S37.

By contrast, when the image forming operation is not performed with an inline image forming apparatus (NO in step S35), the sheet laminator 200a then executes the operation of step S37.

In step S37, the sheet laminator 200a conveys the inner sheet P in the forward conveyance direction (i.e., the direction indicated by arrow A in <FIG>), so as to insert the inner sheet P into the opening of the lamination sheet S. In step S37, when the single sheet insertion mode is selected, the sheet laminator 200a performs the operations illustrated in <FIG>. On the other hand, when the multiple sheet insertion mode is selected, the sheet laminator 200a performs the operations illustrated in <FIG>.

In step S38, the sheet laminator 200a determines whether the selected number of inner sheets P are inserted into the lamination sheet S. When the selected number of inner sheets P are not inserted into the lamination sheet S (NO in step S38), step S38 is repeated until the selected number of inner sheets P are inserted into the lamination sheet S. On the other hand, when the selected number of inner sheets P are inserted into the lamination sheet S (YES in step S38), the sheet laminator 200a then executes the operation of step S39.

Then, in step S39, the sheet laminator 200a causes the branching member motor 118a to rotate the branching member <NUM> to switch (change) the sheet conveyance passage of the lamination sheet S. In step S40, the sheet laminator 200a conveys the lamination sheet S sandwiching the inner sheet P to the thermal fixing unit <NUM>. By application of heat and pressure to the lamination sheet S, the sheet laminating operation completes (see <FIG>).

When the image forming operation is performed with an inline image forming apparatus (YES in step S35), the sheet laminator 200a sends a signal to notify the inline image forming apparatus, for example, the image forming apparatus <NUM> (or the image forming apparatus <NUM> or the image forming apparatus <NUM>) to start the print job, then performs the printing operation on the inner sheet P and conveys the inner sheet P. In this case, the sheet processing device waits until the printed inner sheet P is conveyed and reaches the sheet conveyance sensor C1. The sheet laminator 200a may send the image forming apparatus <NUM> (or the image forming apparatus <NUM> or the image forming apparatus <NUM>) the signal to start the print job in advance based on a time to convey the printed inner sheet P, for example, after the separation members <NUM> complete the operations illustrated in <FIG>. Due to such a configuration, the productivity can be enhanced.

A description is then given of the configuration of the sheet laminator according to an embodiment of the present disclosure.

<FIG> is a diagram illustrating a configuration of a thermal fixing unit <NUM> included in the sheet laminator <NUM> (200a, 200b) according to an embodiment of the present disclosure.

The thermal fixing unit <NUM> applies heat and pressure on the lamination sheet S sandwiching the inner sheet P while conveying the lamination sheet S. The lamination sheet S sandwiching the inner sheet P is hereinafter referred to as a "sheet SP". The thermal fixing unit <NUM> includes a thermal fixing roller pair <NUM>, a heater <NUM>, and a thermal fixing roller motor 129a (see <FIG>). The thermal fixing roller pair <NUM> includes a first thermal fixing roller 120a and a second thermal fixing roller 120b to convey the sheet SP. The heater <NUM> includes a first heater 54a and a second heater 54b to heat the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM>. The thermal fixing roller motor 129a heats the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> (see <FIG>). The thermal fixing unit <NUM> further includes thermistors <NUM> (i.e., the first thermistor 56a and the second thermistor 56b) each serving as a contact temperature detector. The first thermistor 56a is disposed adjacent to the first thermal fixing roller 120a to detect the surface temperature of the surface of the first thermal fixing roller 120a. The second thermistor 56b is disposed adjacent to the second thermal fixing roller 120b to detect the surface temperature of the surface of the second thermal fixing roller 120b.

The first heater 54a is disposed inside a core metal portion 60a in the first thermal fixing roller 120a. The second heater 54b is disposed inside a core metal portion 60b in the second thermal fixing roller 120b. Further, the first thermistor 56a is disposed in contact with the surface of the first thermal fixing roller 120a, and the second thermistor 56b is disposed in contact with the surface of the second thermal fixing roller 120b. The controller <NUM> causes the thermal fixing unit <NUM> to control the first heater 54a and the second heater 54b according to respective temperatures detected by the first thermistor 56a and the second thermistor 56b.

<FIG> is a schematic diagram illustrating a configuration of the thermal fixing roller pair according to an embodiment of the present disclosure.

As illustrated in <FIG>, the first thermal fixing roller 120a of the thermal fixing roller pair <NUM> includes a core metal portion 60a at a center portion of the first thermal fixing roller 120a, an elastic layer 62a (i.e., a rubber layer) disposed around the core metal portion 60a, and a fluororesin layer 64a on the surface of the elastic layer 62a. The second thermal fixing roller 120b of the thermal fixing roller pair <NUM> includes a core metal portion 60b at a center portion of the second thermal fixing roller 120b, an elastic layer 62b (i.e., a rubber layer) disposed around the core metal portion 60b, and a fluororesin layer 64b on the surface of the elastic layer 62b. The elastic layers 62a and 62b (i.e., rubber layers) are crushed to form the nip region N. The fluororesin layers 64a and 64b on the surfaces of the elastic layers 62a and 62b, respectively, can make it difficult for the adhesive leaked from the sheet SP to adhere to the surfaces of the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM>.

In the thermal fixing unit <NUM> of the present embodiment, the first thermal fixing roller 120a and the second thermal fixing roller 120b have a substantially same diameter, a substantially same rigidity, and a substantially same surface releasability. Due to such a configuration, the adhesive oozed from the sheet SP is dispersed to the first thermal fixing roller 120a and the second thermal fixing roller 120b, so that accumulation of the adhesive on only one of the first thermal fixing roller 120a or the second thermal fixing roller 120b can be prevented. As a result, the thermal fixing unit <NUM> can prevent the sheet SP from winding around the first thermal fixing roller 120a or the second thermal fixing roller 120b, and save time to pass a cleaning sheet each time the cleaning sheet is used.

In addition, as the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> are respectively heated from inside, there is no concern that is likely to damage the fluororesin layers 64a and 64b on the corresponding surface layers. In addition, the core metal portions 60a and 60b and the elastic layers 62a and 62b can store heat. Even if heat is removed from the surface layers due to contact with the sheet SP, a decrease in surface temperature can be reduced.

Further, the first thermistor 56a is disposed on the surface of the first thermal fixing roller 120a and is used together with the first heater 54a to control the first thermal fixing roller 120a to a target temperature. Similarly, the second thermistor 56b is disposed on the surface of the second thermal fixing roller 120b and is used together with the second heater 54b to control the second thermal fixing roller 120b to a target temperature. According to detection of respective temperatures of the first thermal fixing roller 120a and the second thermal fixing roller 120b, the first thermal fixing roller 120a and the second thermal fixing roller 120b can control the temperatures equal to each other, and both sides of the sheet SP can be heated at the substantially same temperature. The first thermistor 56a and the second thermistor 56b may be replaced by a non-contact temperature sensor or sensors.

As the thermal fixing roller pair <NUM> can apply heat and pressure on the sheet SP equally from both sides of the sheet SP, the stable lamination quality with less curling can be obtained.

A description is now given of the influence of the adhesive adhering to the thermal fixing roller pair <NUM> on the temperature detector (i.e., the thermistors <NUM>).

<FIG> is a schematic diagram illustrating a state where a first thermistor 56aA is lifted due to adhesive accumulated on the surface of a roller of a thermal fixing roller pair 120A of a typical thermal fixing unit 50A.

The parts and components included in the thermal fixing unit 50A basically have the same structures and functions as the parts and components included in the thermal fixing unit <NUM> according to an embodiment of the present disclosure.

For example, during the sheet laminating operation, the adhesive oozing from the trailing end of the sheet SP adheres to and accumulates on the surface of a first thermal fixing roller 120aA of the thermal fixing roller pair 120A. In addition, when the sheets SP are continuously fed or the lamination sheets (lamination sheets S) having a large amount of glue are used, accumulation of the adhesive is promoted. When the accumulated adhesive <NUM> increases, for example, the first thermistor 56aA is lifted from the surface of the first thermal fixing roller 120aA, and an accurate surface temperature cannot be detected.

A first heater 54aA and a second heater 54bA are subjected to temperature control (feedback control) based on the surface temperatures of the first thermal fixing roller 120aA and a second thermal fixing roller 120bA detected by the first thermistor 56aA and a second thermistor 56bA, respectively. For this reason, if the first thermistor 56aA and the second thermistor 56bA cannot detect the accurate surface temperatures, the temperatures of the first heater 54aA and the second heater 54bA cannot be appropriately controlled, and the qualities of sheet lamination are likely to deteriorate.

Further, even when the first heater 54aA and the second heater 54bA are heated, the detected surface temperatures of the first thermal fixing roller 120aA and the second thermal fixing roller 120bA remain low. In such a case, the first heater 54aA and the second heater 54bA are further heated to excessively increase the surface temperatures of the first heater 54aA and the second heater 54bA, which is likely to lead to smoke and fire.

On the other hand, as the thermal fixing roller pair <NUM> according to the present embodiment has the configuration illustrated in <FIG>, the adhesive is less likely to accumulate on the thermal fixing roller pair <NUM>. Due to such a configuration, the first thermistor 56a and the second thermistor 56b successfully contact the surfaces of the first thermal fixing roller 120a and the second thermal fixing roller 120b, respectively, and can accurately detect the surface temperatures. As a result, the thermal fixing unit <NUM> can perform an accurate temperature control over the heaters <NUM> including the first heater 54a and the second heater 54b.

A description is given below of an advantageous configuration of the sheet laminator <NUM>.

The thermal fixing roller pair <NUM> is preferable to include the first thermal fixing roller 120a having the elastic layer 62a and the fluororesin layer 64a with the total thickness equal to or smaller than <NUM> and the second thermal fixing roller 120b having the elastic layer 62b and the fluororesin layer 64b with the total thickness equal to or smaller than <NUM>. In other words, it is preferable that the elastic layer (i.e., the elastic layers 62a and 62b) and the fluororesin layer (i.e., the fluororesin layer 64a and 64b) of each of the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> have a total thickness equal to or smaller than <NUM>. According to this configuration, a given time difference (dead time) occurs until heat of the first heater 54a and the second heater 54b reach the surface layers of the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM>, respectively, and the surface temperatures of the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> are detected by the first thermistor 56a and the second thermistor 56b, respectively. However, providing the elastic layer and the fluororesin layer having a total thickness equal to or smaller than <NUM> can reduce the time difference and enables accurate temperature control.

<FIG> is a diagram illustrating the configurations of the thermal fixing unit <NUM>, a first conveyance roller pair <NUM>, and a second conveyance roller pair <NUM>, according to an embodiment of the present disclosure.

The sheet laminator <NUM> (200a, 200b) further includes the first conveyance roller pair <NUM> and the second conveyance roller pair <NUM>. The first conveyance roller pair <NUM> is disposed upstream from the thermal fixing unit <NUM> in the sheet conveyance direction and nips the sheet SP and conveys the sheet SP toward the thermal fixing unit <NUM>. The second conveyance roller pair <NUM> is disposed downstream from the thermal fixing unit <NUM> in the sheet conveyance direction and nips the sheet SP and conveys the sheet SP outside the sheet laminator.

The first conveyance roller pair <NUM> forms a nip region N1 between the rollers. The thermal fixing roller pair <NUM> forms a nip region N2 between the first thermal fixing roller 120a and the second thermal fixing roller 120b. The second conveyance roller pair <NUM> forms a nip region N3 between the rollers. The nip region N2 of the thermal fixing roller pair <NUM> is on a straight line connecting the nip region N1 of the first conveyance roller pair <NUM> and the nip region N3 of the second conveyance roller pair <NUM>.

As illustrated in <FIG>, the sheet SP is conveyed by the first conveyance roller pair <NUM> to the thermal fixing unit <NUM> (i.e., the thermal fixing roller pair <NUM>). At this time, when the leading end or the downstream portion of the sheet SP reaches the nip region N2 of the thermal fixing roller pair <NUM>, the trailing end or the upstream portion of the sheet SP is being conveyed by the first conveyance roller pair <NUM>. In other words, the sheet SP is conveyed by the first conveyance roller pair <NUM> and the thermal fixing roller pair <NUM>.

When the sheet conveying speed (i.e., the linear velocity V1) of the first conveyance roller pair <NUM> is slower than the sheet conveying speed (i.e., the linear velocity V2) of the thermal fixing roller pair <NUM> (V1 < V2), the thermal fixing roller pair <NUM> pulls the sheet SP from the first conveyance roller pair <NUM>. In this case, the sheet conveying speed of the inner sheet P varies the sheet conveying speed of the lamination sheet S while the lamination sheet S sandwiching the inner sheet P is thermally fixed. Due to this action, it is likely to cause the poor quality such as a non-uniform adhesion of the lamination sheet S.

For this reason, it is desirable that the sheet conveying speed (V1) of the first conveyance roller pair <NUM> is faster than the sheet conveying speed (V2) of the thermal fixing roller pair <NUM> (V1 > V2), so that the sheet SP is not pulled by the thermal fixing roller pair <NUM>. As a result, a stable sheet conveying speed of the sheet SP can be achieved, and a stable lamination quality can be obtained.

Alternatively, the conveyance force (F2) of the thermal fixing roller pair <NUM> may be greater than the conveyance force (F1) of the first conveyance roller pair <NUM> (F1 < F2), and the sheet SP may slip on the first conveyance roller pair <NUM>. Also in this case, the conveying speed of the sheet SP can be constant while the lamination sheet S sandwiching the inner sheet P is thermally fixed.

The conveyance force (F1) of the first conveyance roller pair <NUM> is force generated between the nip region N1 of the first conveyance roller pair <NUM> and the sheet SP, and the conveyance force (F2) of the thermal fixing roller pair <NUM> is force generated between the nip region N2 of the thermal fixing roller pair <NUM> and the sheet SP.

The conveyance force (F1) is determined by the contact area of the nip region N1 of the first conveyance roller pair <NUM> and the sheet SP, the kinetic coefficient of friction between the contact surfaces, and the pressure force between the rollers of the first conveyance roller pair <NUM>. The same manner is applied to the conveyance force (F2).

Then, as illustrated in <FIG>, the sheet SP fixed with the thermal fixing roller pair <NUM> is conveyed toward the second conveyance roller pair <NUM>. When the leading end or the downstream portion of the sheet SP reaches the nip region N3 of the second conveyance roller pair <NUM>, the trailing end or the upstream portion of the sheet SP is being conveyed by the thermal fixing roller pair <NUM>. For this reason, the sheet SP is conveyed by the thermal fixing roller pair <NUM> and the second conveyance roller pair <NUM>.

In conveyance of the sheet SP between the thermal fixing roller pair <NUM> and the second conveyance roller pair <NUM>, it is desirable that the conveying speed of the sheet SP is the same or substantially the same as the conveying speed of the thermal fixing roller pair <NUM> while the second conveyance roller pair <NUM> pulls the sheet SP from the thermal fixing roller pair <NUM>.

As the second conveyance roller pair <NUM> pulls the sheet SP, occurrence of curling is reduced. Further, the sheet SP can be thermally fixed in synchrony with the conveying speed of the thermal fixing roller pair <NUM>.

Accordingly, the sheet conveying speed (i.e., the linear velocity V3) of the second conveyance roller pair <NUM> is set faster than the sheet conveying speed (i.e., the linear velocity V2) of the thermal fixing roller pair <NUM> (V3 > V2) and the conveyance force (F3) of the second conveyance roller pair <NUM> is the magnitude of force by which the second conveyance roller pair <NUM> conveys the sheet SP conveyed by the thermal fixing roller pair <NUM> while causing the sheet SP to slip on the thermal fixing roller pair <NUM>. In other words, the conveyance force (F3) of the second conveyance roller pair <NUM> is set smaller than the conveyance force (F2) of the thermal fixing roller pair <NUM> (F3 < F2), so that the sheet SP is conveyed while slipping on the second conveyance roller pair <NUM>.

Due to such a configuration, at the time of thermal fixing, the sheet SP is nipped and conveyed by the thermal fixing roller pair <NUM> and the second conveyance roller pair <NUM>. However, the conveyance can be substantially controlled by the thermal fixing roller pair <NUM>. As a result, while being linearly conveyed, the sheet SP can be thermally fixed in accordance with the sheet conveying speed of the thermal fixing roller pair <NUM>.

<FIG> are diagrams, each illustrating a schematic configuration of the thermal fixing roller pair <NUM> that can change the distance between the centers of the rollers of the thermal fixing roller pair <NUM>, according to an embodiment of the present disclosure.

Specifically, <FIG> is a diagram illustrating a schematic configuration of the thermal fixing roller pair <NUM> in a state where the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> are in contact with each other, and <FIG> is a diagram illustrating a schematic configuration of the thermal fixing roller pair <NUM> in a state where the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> are separated from each other.

<FIG> and <FIG> are diagrams each illustrating a moving mechanism that contacts the rollers of the thermal fixing roller pair <NUM> with each other and separates the rollers of the thermal fixing roller pair <NUM> from each other.

Specifically, <FIG> illustrates a contact state of the thermal fixing roller pair <NUM>, and <FIG> illustrates a separation state of the thermal fixing roller pair <NUM>. The moving mechanism <NUM> contacts or separates from the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM>. The moving mechanism <NUM> includes a movable bracket <NUM>, a movable bracket drive cam <NUM>, and a biasing spring <NUM> serving as a biasing member. The first thermal fixing roller 120a (on the left in <FIG> and <FIG>) of the thermal fixing roller pair <NUM> is fixed and the second thermal fixing roller 120b (on the right in <FIG> and <FIG>) is rotatably supported by a shaft 120c at one end of the movable bracket <NUM>. The movable bracket <NUM> has a bent shape. The shaft 120c of the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> is fixed to one end the movable bracket <NUM>. The movable bracket <NUM> is disposed to be movable around a movable bracket rotational support 191a. Further, the movable bracket <NUM> is biased by the biasing spring <NUM> to be rotatable in the counterclockwise direction around the movable bracket rotational support 191a so that the first thermal fixing roller 120a and the second thermal fixing roller 120b of the thermal fixing roller pair <NUM> contact with each other as illustrated in <FIG>. The movable bracket drive cam <NUM> is rotatable by the cam drive motor <NUM>. As the movable bracket drive cam <NUM> rotates to the position illustrated in <FIG>, the movable bracket <NUM> to which force is applied by the movable bracket drive cam <NUM> rotates in the clockwise direction around the movable bracket rotational support 191a against the biasing force of the biasing spring <NUM>. In response to this operation, the second thermal fixing roller 120b that is movable separates from the first thermal fixing roller 120a that is fixed. As a result, the thermal fixing roller pair <NUM> is brought into the separation state.

As described above, the distance between the rotational center of the first thermal fixing roller and the rotational center of the second thermal fixing roller are changeable by a moving mechanism <NUM>. Due to such a configuration, the nip pressure can be changed.

In <FIG>, the second thermal fixing roller 120b, the second heater 54b, and the second thermistor 56b are moved together. However, when an amount of movement is relatively small, the second thermal fixing roller 120b alone may be moved. Alternatively, the first thermal fixing roller 120a, the first heater 54a, and the first thermistor 56a may be moved together.

The distance between the rotational center of the first thermal fixing roller and the rotational center of the second thermal fixing roller are changeable in response to an instruction by a user. For example, an instruction can be sent to the sheet laminator <NUM> (200a, 200b) using the operation panel <NUM>. As a result, for example, when the sheet SP is jammed in the thermal fixing roller pair <NUM>, the user can easily perform jam processing.

Some embodiments of the present disclosure have been described in detail above. The above-described embodiments are examples and can be modified within the scope of the claims.

The effects obtained by the above-described embodiments are examples. The effects obtained by other embodiments are not limited to the above-described effects.

The present disclosure is not limited to specific embodiments described above, and numerous additional modifications and variations are possible in light of the teachings within the technical scope of the appended claims. It is therefore to be understood that, the disclosure of this patent specification may be practiced otherwise by those skilled in the art than as specifically described herein, as long as such modifications, alternatives are within the technical scope of the appended claims.

The effects described in the embodiments of this disclosure are listed as the examples of preferable effects derived from this disclosure, and therefore are not intended to limit to the embodiments of this disclosure.

The embodiments described above are presented as an example to implement this disclosure. The embodiments described above are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, or changes can be made without departing from the scope of the claims.

Claim 1:
A thermal fixer (<NUM>) comprising:
a first thermal fixing roller (120a) including a first heater (54a); and
a second thermal fixing roller (120b) pressed to the first thermal fixing roller (120a), the second thermal fixing roller (120b) including a second heater (54b) and has a diameter, a rigidity, and a surface releasability substantially identical to the first thermal fixing roller (120a),
characterised in that each of the first thermal fixing roller (120a) and the second thermal fixing roller (120b) includes:
a core metal portion (60a, 60b) at a center portion of each of the first thermal fixing roller (120a) and the second thermal fixing roller (120b);
an elastic layer (62a, 62b) around the core metal portion (60a, 60b); and
a fluororesin layer (64a, 64b) on a surface of the elastic layer (62a, 62b),
wherein a total thickness of the elastic layer (62a, 62b) and the fluororesin layer (64a, 64b) of each of the first thermal fixing roller (120a) and the second thermal fixing roller (120b) is equal to or smaller than <NUM>.