Sheet feeding device and image forming apparatus

Abstract

The sheet feeding device includes a first pair of feeding rollers, a reference member, an inclined feeding roller, a second pair of feeding rollers, a detection unit, and a controller. Before the sheet is inclinedly fed by the inclined feeding rollers, the controller causes the first feeding rollers to move the sheet to a predetermined position in the width direction of the sheet based on the detection result of the detection means.

Description

Technology Field

[0001] The present invention relates to a sheet feeding device for feeding a sheet and an image forming device including the sheet feeding device. Background Technology

[0002] Conventionally, an image forming device is used that can correct the positional misalignment of the sheet and the tilting movement of the sheet in the width direction of the sheet, which is orthogonal to the sheet feeding direction, while feeding the sheet.

[0003] For example, Japanese Patent Publication No. Hei 11-189355 discloses a sheet feeding device of the so-called side registration type, which feeds the sheet toward a reference member by means of an inclined feed roller while displacing the sheet laterally, brings the sheet into contact with the reference member at its side end, corrects the inclined movement thereby, and feeds the sheet to a pair of downstream rollers.

[0004] However, in the side registration method, with the side edge of the sheet in contact with the reference member, the sheet is fed to the downstream pair of rollers along the reference member while sliding the inclined feed roller against the sheet.

[0005] In this case, when the side edge of the sheet begins to come into contact with the reference member, the timing until the sheet reaches the downstream roller pair changes depending on the position of the sheet relative to the feed direction.

[0006] For example, when the side end of the sheet begins to come into contact with the reference member from the upstream side of the reference member, the feeding distance over which the sheet is fed while the side end of the sheet is in contact with the reference member is long. That is, the distance over which the inclined feeding roller feeds the sheet while sliding against the sheet becomes long. Consequently, since it takes some time for the sheet to reach the downstream roller pair, the timing of the sheet reaching the downstream roller pair is delayed. On the other hand, when the side end of the sheet begins to come into contact with the reference member from the downstream side of the reference member, the feeding distance over which the sheet is fed while the side end of the sheet is in contact with the reference member is short. Consequently, the time it takes for the sheet to reach the downstream roller pair is also shortened, so the timing of the sheet reaching the downstream roller pair is accelerated.

[0007] Here, the position of the sheet in the feed direction when the side edge of the sheet begins to come into contact with the reference member depends on the distance between the side edge of the sheet in the width direction and the reference member when the inclined feed roller begins inclined feeding of the sheet. As a result, if the positional variation of the side edge of the sheet in the width direction is large before the inclined feed roller inclines the sheet, the positional variation of the sheet in the feed direction when the leading edge of the sheet reaches the downstream roller pair becomes large. Therefore, in the conventional configuration, it is necessary to increase the gap between the current sheet and the subsequent sheet while considering the positional variation of the sheet in the sheet feed direction, and thus the productivity of the sheet feed device (image forming device) is not high. The problem to be solved

[0008] The main objective of the present invention is to improve the productivity of a sheet feeding device (image forming device) when tilt movement correction of the side registration method is performed. means of solving the problem

[0009] According to one embodiment of the present invention, a first feed roller pair configured to feed the sheet, which is movable in the width direction of the sheet orthogonal to the sheet feed direction while the sheet is in a nipped state; a reference member provided downstream of the first feed roller pair with respect to the sheet feed direction and extending in the sheet feed direction, wherein the reference member includes a contact surface in which the end of the sheet in the width direction of the sheet can contact; an inclined feed roller configured to feed the sheet in an inclined direction with respect to the sheet feed direction such that as the sheet moves toward the downstream side of the sheet feed direction, the sheet approaches the contact surface in the width direction of the sheet; a second feed roller pair configured to feed the sheet fed by the inclined feed roller; and a detection means provided upstream of the first feed roller pair with respect to the sheet feed direction and configured to detect the position of the end of the sheet in the width direction of the sheet. A sheet feeding device is provided, comprising a controller configured to control the movement of the first pair of feeding rollers in the width direction of the sheet, wherein, before the sheet is inclined fed by the inclined feeding roller, the controller causes the first feeding roller to move the sheet to a predetermined position in the width direction of the sheet based on the detection result of the detection means.

[0010] Further objects of the present invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Brief explanation of the drawing

[0011] Figure 1 is a schematic diagram of the printer of embodiment 1. FIG. 2 is a schematic diagram of the registration section of Embodiment 1. Figure 3 is a schematic diagram of a conventional registration unit as a reference example. FIG. 4 is a schematic diagram illustrating the velocity components of a sheet being fed through a registration section in a reference example. Part (a) of FIG. 5 is a schematic diagram illustrating a sheet being fed at a position where the distance from the reference member to the side end of the sheet in a reference example is shorter than the distance from the reference member to the inclined feed roller, and Part (b) of FIG. 5 is a schematic diagram illustrating a sheet being fed at a position where the distance from the reference member to the side end of the sheet in a reference example is longer than the distance from the reference member to the inclined feed roller. Figure 6 is a graph (plot) illustrating the relationship between the change in the feed speed of the sheet during slope movement correction and the distance (L) before slope movement correction in a reference example. Part (a) of FIG. 7 is a cross-sectional view illustrating the pressurized state by the pressurizing mechanism of Embodiment 1, and part (b) of FIG. 7 is a cross-sectional view illustrating the released pressurized state by the pressurizing mechanism of Embodiment 1. FIG. 8 is a perspective view illustrating the driving configuration of the feed unit of embodiment 1. Part (a) of FIG. 9 is a schematic diagram of the inclination movement correction part of Embodiment 1 viewed from above, and part (b) of FIG. 9 is a schematic diagram showing the cross-sectional configuration of the reference member of the inclination movement correction part of Embodiment 1 viewed from the sheet feeding direction. Part (a) of FIG. 10 is a perspective view illustrating the pressurization configuration of the pressurization mechanism of Embodiment 1, and part (b) of FIG. 10 is a side view illustrating the pressurization configuration of the pressurization mechanism of Embodiment 1. Part (a) of FIG. 11 is a schematic diagram illustrating the pressurized state by the pressurizing mechanism of Embodiment 1, and part (b) of FIG. 11 is a schematic diagram illustrating the released pressurized state by the pressurizing mechanism of Embodiment 1. FIG. 12 is a perspective view illustrating the placement position of the sheet position detection sensor of embodiment 1. FIG. 13 is a schematic perspective view of a roller driving mechanism for driving a sliding roller of embodiment 1. FIG. 14 is a schematic perspective view of a sliding mechanism for a sliding roller of embodiment 1. Part (a) of FIG. 15 is an enlarged perspective view of a pressure release mechanism for a sliding roller of Embodiment 1, and part (b) of FIG. 15 is a cross-sectional view of a pressure release mechanism for a sliding roller of Embodiment 1. FIG. 16 is a functional block diagram illustrating the control configuration of the registration unit of Embodiment 1. FIG. 17 is a flowchart showing the flow of the sheet feeding operation in the registration section of Embodiment 1. FIG. 18 is a schematic diagram of the registration section of embodiment 2. FIG. 19 is a functional block diagram illustrating the control configuration of the registration unit of embodiment 2. FIG. 20 is a flowchart showing the flow of the sheet feeding operation in the registration section of Embodiment 2. FIG. 21 is a schematic diagram of the registration section of embodiment 3. Part (a) of FIG. 22 is a perspective view illustrating the structure of the reference member moving mechanism of Embodiment 3, and part (b) of FIG. 22 is a cross-sectional view illustrating the bearing part of the reference member moving mechanism of Embodiment 3. FIG. 23 is a functional block diagram illustrating the control configuration of the registration unit of embodiment 3. FIG. 24 is a flowchart showing the flow of the sheet feeding operation in the registration section of Embodiment 3. Specific details for implementing the invention

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0013] [Embodiment 1]

[0014] <Overall Structure of the Image Forming Device>

[0015] First, the schematic structure of the printer (1) as an image forming device of Embodiment 1 will be described. FIG. 1 is a schematic configuration diagram of the printer (1). The printer (1) is a device such as a printer, copier, fax machine, or multifunction printer that forms an image on a sheet used as a recording medium (material) based on image information input from an external PC or image information read from a manuscript. In addition, the printer (1) can handle printing other than general office printing and can use various sheets as a recording medium (material), including paper such as form paper or envelopes, glossy paper, plastic film such as an overhead projector (OHP) sheet, cloth, etc.

[0016] The device main assembly (1A) of the printer (1) accommodates a feed cassette (51) for receiving a sheet (S) and an image forming engine (513) for forming an image on the sheet (S) fed from the feed cassette (51). The image forming engine (513), which is an example of an image forming means, is a tandem intermediate transfer type engine unit comprising four image forming sections (PY, PM, PC, and PK) for forming yellow, magenta, cyan, and black toner images, respectively, and an intermediate transfer belt (506). The image forming sections (PY to PK) are each electrophotographic units comprising photosensitive drums (1Y, 1M, 1C, and 1K) which are photosensitive members.

[0017] The image forming units (PY to PK) achieve commonality in their composition, except that the toner colors used for development are different. In this embodiment, the structure of the image forming engine (513) and the toner image forming process (image forming operation) are explained by using a yellow image forming unit (PY) as an example. The image forming unit (PY) includes, in addition to the photosensitive drum (1Y), an exposure device (511), a developing device (510), and a drum cleaner (509). The photosensitive drum (1Y) is a drum-type photosensitive member that includes a photosensitive layer on its outer periphery and rotates in a direction (direction of arrow A in FIG. 1) following the rotation direction of the intermediate transfer belt (506) (direction of arrow B in FIG. 1). The surface of the photosensitive drum (1Y) is charged by receiving an electric charge from a charging means such as a charging roller. The exposure device (511) emits laser light modulated according to image information, and thus the surface of the photosensitive drum (1Y) is scanned by the laser light by an optical system including a reflector (512), and accordingly, an electrostatic latent image is formed on the surface of the photosensitive drum (1Y). The developing device (510) receives a developer containing toner and supplies toner to the surface of the photosensitive drum (1Y) to visualize (develop) the electrostatic latent image into a toner image. The toner image formed on the photosensitive drum (1Y) is transferred first to the intermediate transfer belt (506) from the nip section (first transfer section) between the first transfer roller (507) and the intermediate transfer belt (506). After transfer, any residual toner remaining on the photosensitive drum (1Y) is removed by a drum cleaner (509).

[0018] The intermediate transfer belt (506) is wound around the driving roller (504), the driven roller (505), the inner secondary transfer roller (503), and the primary transfer roller (507), and is driven to rotate in the clockwise direction (arrow B direction) of FIG. 1 by the driving roller (504). The image forming operation described above is performed in parallel in the image forming section (PY to PK), and four color toner images are transferred in a multi-transfer method so that they overlap each other, thereby forming a full-color image on the intermediate transfer belt (506). These toner images for the full-color image are carried on the intermediate transfer belt (506) and fed to the secondary transfer section (T). The secondary transfer section (T) is configured as a nip section between the secondary transfer roller (56) and the inner secondary transfer roller (503) as a transfer means. A bias voltage with a polarity opposite to the charge polarity of the toner is applied to the secondary transfer roller (56). By this, the toner image is secondarily transferred to the sheet (S). After the transfer, any residual toner remaining on the intermediate transfer belt (506) is removed by a belt cleaner.

[0019] The sheet (S) on which the toner image is transferred is delivered to the fixing unit (58) by the fixing feed unit (57). The fixing unit (58) includes a pair of fixing rollers that feed the sheet (S) while supporting it, and a heat source such as a halogen heater, and applies pressure and heat to the toner image contained in the sheet (S). As a result, the toner particles are melted and fixed, and the toner image is fixed to the sheet (S).

[0020] Next, the structure and operation of a sheet feeding system that feeds a sheet (S) contained in a feed cassette (51) and discharges the sheet (S) with an image formed thereon to the outside of the device main assembly (1A) will be described. The sheet feeding system includes a sheet feeding unit (54), a feeding (return) unit (50), an inclination movement correction unit (55), a branching feeding (return) unit (59), an inversion feeding (return) unit (501), and a double-sided feeding (return) unit (502).

[0021] The feed cassette (51) is mounted so as to be retractable on the main assembly (1A) of the device and receives a sheet (S) while loaded on a lifting plate (52) that can be raised and lowered. The sheet (S) is fed one sheet at a time by a feed unit (53). As for the types of the feed unit (53) which is the sheet feeding means, there is a belt method (see FIG. 1) in which the sheet (S) is sucked onto a belt member by a suction fan and fed, and a friction separation method using a roller or pad. The sheet (S) fed from the feed unit (53) is fed along the feed passage (54a) by a pair of feed rollers, passes through the feed section (50), and is then delivered to the inclination movement correction section (55).

[0022] The transmitted sheet (S) is fed toward the secondary transfer unit (T) after tilt movement correction and timing correction are performed in the tilt movement correction unit (55). At this time, the registration roller pair (7), which is the second feeding roller pair included in the tilt movement correction unit (55), sends the sheet (S) to the secondary transfer unit (T) at a timing synchronized with the progress of the image formation operation by the image formation unit (PY to PK) based on the detection signal of the registration sensor (8). The sheet (S), on which the toner image is transferred in the secondary transfer unit (T) and the image is fixed by the fixing unit (58), is fed to a branch feeding unit (59) that includes a switching member capable of switching the feeding path of the sheet (S). When the image formation for the sheet (S) is completed, the sheet (S) is discharged by the discharge roller pair to a discharge tray (500) placed on the outside of the device main assembly (1A). When an image is formed on the back side (side) of the sheet (S), the sheet (S) is transferred to the double-sided feed unit (502) through the reverse feed unit (501). The reverse feed unit (501) includes a pair of reverse rollers capable of forward and reverse rotation, and after switching back the sheet (S), transfers the sheet (S) to the double-sided feed unit (502). The double-sided feed unit (502) feeds the sheet (S) toward the feed unit (50) through a re-feed passage (54b) that joins the feed passage (54a). After forming an image on the back side of the sheet (S), the sheet (S) is discharged into the discharge tray (500).

[0023] Furthermore, the above-described configuration is an example of an image forming device, and for example, the image forming device may be an image forming device provided with an inkjet-type image forming means instead of an electrophotographic method. In addition, there is an image forming device provided with auxiliary (optional) devices such as an optional feeder or a sheet processing device in addition to the main assembly of the device provided with the image forming means, but the configuration of the sheet feeding device described below may be used for feeding sheets from such auxiliary devices.

[0024] <Overview of the Registration Department>

[0025] Next, with reference to FIG. 2, the configuration of the registration unit (5) constituting the sheet feeding device will be described. FIG. 2 is a schematic diagram of the registration unit (5). FIG. 2 also shows the configuration (structure) of the registration unit (5) when viewed from above the main assembly (1A) of the device (see FIG. 1). As shown in FIG. 2, the registration unit (5) includes a feeding unit (50) that feeds the sheet in the sheet feeding direction and an inclination movement correction unit (55) positioned downstream of the feeding unit (50) with respect to the sheet feeding direction. Additionally, the registration unit (5) includes a sheet position detection sensor (60) that detects the position of the end of the sheet in the width direction orthogonal to the sheet feeding direction, and a sliding mechanism (600) that moves the roller constituting the feeding unit (50) in the width direction orthogonal to the sheet feeding direction. The feed section (500) includes at least one pair of feed rollers, and FIG. 2 shows a configuration in which feed rollers (34-1, 34-2, 34-3, and 34-4) are provided. In the following description, when there is no need to distinguish between the feed rollers (34-1, 34-2, 34-3, and 34-4), these feed rollers are referred to as "feed rollers (34)". The feed rollers (34) feed (dispatch) the sheet in the sheet feed direction. Additionally, in the registration section (5), a sliding mechanism (600) is provided on the feed rollers (34-4). Also, FIG. 2 shows an example configuration in which a sheet position detection sensor (60) capable of detecting the side end position is placed at a position between the feed rollers (34-2) and the feed rollers (34-3). The sheet position detection sensor (60) may be placed in a position other than the position shown in FIG. 2 that can detect the widthwise end of the sheet being fed through the feeding unit (50), for example, a position between the feeding roller (34-4) and the feeding roller (34-3).

[0026] The inclination movement correction unit (55) is provided with an inclination feed roller (32-1, 32-2, and 32-3), a reference member (31), and a pair of registration rollers (7). In the following description, when there is no need to distinguish between the inclination feed rollers (32-1, 32-2, and 32-3), these inclination feed rollers are referred to as "inclination feed rollers (32)". The reference member (31) includes a reference surface (301) (see part (b) of FIG. 9) extending in the sheet feed direction and is positioned on either side of the sheet feed passage with respect to the width direction of the sheet which is orthogonal to the sheet feed direction. The reference surface (301) extends along the sheet feed direction and corresponds to a contact surface that can contact one end of the sheet in the width direction, i.e., the side end of the sheet.

[0027] A pre-registration sensor (P) for detecting the passage of a sheet is provided near the feed roller (34-4). As the pre-registration sensor (P), for example, a reflective photoelectric sensor including a light-emitting part and a light-receiving part may be used. In this case, light emitted from the light-emitting part is reflected by the sheet that has reached the detection position, and the reflected light is detected by the light-receiving part, thereby detecting the timing of the sheet's passage. In FIG. 2, the pre-registration sensor (P) is positioned between the feed roller (34-4) and the inclined feed roller (32-1) in the sheet feed direction.

[0028] Each inclined feed roller (32-1, 32-2, and 32-3) rotates around an axis inclined with respect to the width direction. That is, the inclined feed rollers (32-1, 32-2, and 32-3) are arranged parallel to each other such that the tangential direction at the contact portion with the sheet is inclined at an angle (α) with respect to the sheet feed direction. Accordingly, by rotating in contact with the sheet, the inclined feed rollers (32-1, 32-2, and 32-3) move the sheet so that it approaches the reference plane (301) of the reference member (31) in the width direction as the sheet is fed toward the downstream side of the sheet feed direction (V). Additionally, the sheet moves so that it approaches the reference plane (301) as the sheet is fed toward the downstream side of the sheet feed direction (V).

[0029] Here, the inclination correction of the sheet by the inclination correction unit (55) is described. The inclination correction unit (55) corrects the inclination of the sheet by the so-called side registration method. Specifically, the inclination correction unit (55) contacts the side end of the sheet, i.e., the end of the sheet in the width direction, with a reference member (31) having a reference surface (301) which is a contact surface extending along the sheet feed direction. Then, after the sheet contacts the reference surface (301), the inclination of the sheet is corrected by moving the side end of the sheet along the reference surface (301). In addition, the sheet feed direction is the direction of the sheet's movement before the sheet approaches the reference member (31) in the inclination correction unit (55), and in this embodiment, it refers to the feed direction of the sheet by the feed roller (34) of the feed unit (50).

[0030] Additionally, the slope movement correction unit (55) is provided with a pre-registration sensor (Q) in addition to the pre-registration sensor (P). The pre-registration sensor (Q) is positioned downstream of the slope feed roller (32) and upstream of the registration roller pair (7) with respect to the sheet feed direction. As the pre-registration sensor (Q), a known sensor such as a reflective photoelectric sensor, similar to the pre-registration sensor (P), may be used.

[0031] The registration roller pair (7) can slide in the sheet width direction perpendicular to the sheet feed direction while the sheet is supported. The registration roller pair (7) moves the sheet, whose side end contacts the reference surface (301) of the reference member (31), in the width direction to match the position of the image transferred from the secondary transfer unit (T). By doing so, the sheet moves so that the center of the sheet in the width direction, which has been corrected for inclination movement in the registration unit (5), becomes the feed center of the printer (1) in the design. Furthermore, the method of aligning the position of the sheet and the image formed on the sheet is not limited to this, and, for example, a configuration may be adopted in which the position of the reference member (31) and the registration roller pair (7) in the width direction is fixed and the position of the toner image formed by the image forming unit (PY to PK) is adjusted.

[0032] Next, as a reference example, the change in the feed speed of the sheet during tilt movement correction is explained by citing the configuration of a conventional registration unit (5A). FIG. 3 is a schematic diagram illustrating the general structure of a conventional registration unit (5A) in a reference example. The registration unit (5A) has a configuration in which the sliding mechanism (600) and the sheet position detection sensor (60) are omitted from the registration unit (5) of the present embodiment. That is, the registration unit (5A) corresponds to a configuration in which, with respect to the registration unit (5), a configuration is not provided for moving the roller constituting the feed unit (50) in the width direction of the sheet that is orthogonal to the sheet feed direction. Therefore, in FIG. 3, components that overlap with the registration unit (5) are indicated by the same reference number or symbol as in FIG. 2, and redundant descriptions are omitted.

[0033] Additionally, FIG. 4 is a schematic diagram illustrating the velocity component of a sheet fed through the registration unit (5A). Parts (a) and (b) of FIG. 5 are schematic diagrams illustrating the relative position between the sheet fed through the registration unit (5A) and the reference member (31), respectively. The conventional registration unit (5A) does not include a configuration that moves the roller constituting the feeding unit (50) in the width direction orthogonal to the sheet feeding direction. Therefore, the sheet is displaced laterally toward the reference member (31) by the inclined feeding roller (32) and then fed along the reference member (31), thereby correcting the inclined movement of the sheet. Here, as shown in FIG. 4, the velocity component in the sheet feeding direction of the sheet fed through the registration unit (5A) is velocity (V1), and the velocity component in the width direction of the sheet orthogonal to the sheet feeding direction is velocity (V2). In addition, in each of parts (a) and (b) of FIG. 5, the distance between the end in the width direction orthogonal to the sheet feeding direction of the sheet (S) fed through the registration part (5A) and the reference member (31) is represented as the distance (L).

[0034] Part (a) of FIG. 5 illustrates a case where, with respect to the width direction, the end of the sheet (S) is closer to the reference plane (301) of the reference member (31) than the inclined feed roller (32). Additionally, part (b) of FIG. 5 illustrates a case where, with respect to the width direction, the end of the sheet (S) is further from the reference plane (301) of the reference member (31) than the inclined feed roller (32). As shown in part (a) of FIG. 5, when the distance (L) is relatively small, the sheet comes into contact with the reference member (31) near the center of the inclined movement correction part (55) with respect to the sheet feed direction. On the other hand, as shown in part (b) of FIG. 5, when the distance (L) is relatively large, the sheet comes into contact with the reference member near the left end of the inclined movement correction part (55) with respect to the sheet feed direction. That is, when the distance (L) is relatively small, the sheet (S) begins to receive frictional resistance from the reference member (31) early, so the distance over which the sheet (S) receives frictional resistance becomes longer, and consequently, the speed (V1) becomes slower. On the other hand, when the distance (L) is relatively large, the sheet (S) comes into contact with the reference member (31) later. As a result, the distance over which the sheet (S) receives frictional resistance from the reference member (31) becomes relatively shorter, and the speed (V1) becomes faster. In this way, when correcting the inclination movement of the sheet by bringing the sheet into contact with the reference member (31), a change in the distance (L) before the inclination movement correction occurs, and as shown in FIG. 6, it causes a change in the feed speed of the sheet during the inclination movement correction. FIG. 6 is a graph (plot) illustrating the relationship between the change in the feed speed of the sheet during the inclination movement correction and the distance (L) before the inclination movement correction. As shown in Fig. 6, it is observed that the speed (V1) during slope correction tends to increase as the distance (L) increases. Therefore, it can be said that the variation in the distance (L) before slope correction is one of the causes of the variation in the speed (V1) during slope correction.Changes in sheet feed speed during tilt movement correction are one of the factors that impair printing productivity.

[0035] Additionally, variations in distance (L) are caused by the sheet setting method by the user or variations in feeding during sheet feeding. Meanwhile, in this embodiment, a sheet position detection sensor (60) that detects the end position of the sheet in the width direction and a sliding mechanism (600) that moves the roller constituting the feeding unit (50) in the width direction are provided. Then, by detecting the side end position of the sheet before tilt movement correction by the sheet position detection sensor (60) and moving the roller constituting the feeding unit (50), variations in distance (L) are corrected to perform tilt movement correction of the sheet.

[0036] <Composition of the Rapid Delivery Unit>

[0037] The configuration of the feed unit (50) will be explained in detail using parts (a) and (b) of FIG. 7 and FIG. 8. Parts (a) and (b) of FIG. 7 are schematic diagrams illustrating the cross-sectional structure of the feed unit (50). FIG. 8 is a perspective view illustrating the driving configuration of each feed roller (34).

[0038] Each feed roller (34-1, 34-2, and 34-3) is composed of a drive roller (13) into which a driving force is input and a driven roller (14) that is driven and rotated by the drive roller (13) (parts (a) and (b) of FIG. 7). The feed roller (34) can be switched between a pressurized state (part (a) of FIG. 7) in which a sheet can be fitted and supported in the nip and a release state (part (b) of FIG. 7) in which the nip is released. Additionally, whether all feed rollers (34) can be switched between the pressurized state and the release state can be determined by the maximum size of the sheet that can be fed by the printer (1).

[0039] The feed section (50) is provided with a cam mechanism (100) including an eccentric roller (103) as a first switching means capable of switching the state of each feed roller (34-1, 34-2, and 34-3) between a pressurized state and a separated state. The eccentric roller (103) is rotatably driven through gears (105 and 106) by a feed drive motor (Md) as a driving source and swings an arm member (101) that contacts the cam surface of its outer circumference. The arm member (101) is supported to swing about a swing shaft (102) with respect to a stay member (18), and the arm member (101) contacts the eccentric roller (103) at one end of the swing shaft (102) and supports the driven shaft (20), which is the rotation axis of the driven roller (14), at the other end. Due to the oscillation of the arm member (101), the driven roller (14) appears in or disappears from the sheet feed passage. Accordingly, by controlling the rotation angle of the eccentric roller (103) through the feed roller drive motor (Md), which is a stepping motor, the positional relationship between the driven roller (14) and the drive roller (13) can be switched. That is, by controlling the rotation angle of the eccentric roller (103), the state of each feed roller (34) can be switched between a separated state in which the driven roller (14) is separated from the drive roller (13) and a pressed state in which the driven roller (14) is pressed against the drive roller (13).

[0040] As shown in FIG. 8, the drive roller (13) is a rubber roller provided on the drive roller shaft (301A) and is connected to the feed roller drive motor (Md), which is the drive source, through a belt drive mechanism (302). The feed roller drive motor (Md) is a stepping motor and is configured to change the timing of the start and stop of the drive and the drive speed (peripheral speed) of the drive roller (13).

[0041] <Composition of the Slope Movement Correction Unit>

[0042] Next, the configuration of the inclination movement correction unit (55) will be explained in detail using FIGS. 9 to 11. Part (a) of FIG. 9 is a schematic diagram of the inclination movement correction unit (55) viewed from above, and part (b) of FIG. 9 is a schematic diagram showing the cross-sectional structure of the reference member (31) viewed from the sheet feeding direction (V) shown in part (a) of FIG. 9. Part (a) of FIG. 10 is a perspective view showing the pressure configuration of the pressure mechanism (33), and part (b) of FIG. 10 is a side view of the pressure mechanism (33). Parts (a) and (b) of FIG. 11 are schematic diagrams showing the pressure state and the pressure release state, respectively, by the pressure mechanism (33).

[0043] As shown in part (a) of FIG. 9, the rotational axes of the inclined feed rollers (32-1, 32-2, and 32-3) are each fixed by universal joints (321, 321, and 321) in a state where the respective rotational axis line is inclined to coincide with an angle (α). Each inclined feed roller (32) is connected to a correcting roller drive motor (Ms), which is a driving source, through a driving mechanism comprising a universal joint (321), a belt (323), and a pulley. The correcting roller drive motor (Ms) is a stepping motor and can control the feed speed and the start and stop timing of the drive.

[0044] As shown in part (b) of FIG. 9, the reference member (31) has a concave cross-section including a reference surface (301) that contacts the side end of the sheet (S), an upper opposing surface that can face the upper surface of the sheet (S), and a lower opposing surface that can face the lower surface of the sheet (S). As the material for the reference member (31), a fluorine-containing resin material, such as PTFE (polytetrafluoroethylene), which is formed by aluminum die casting, has its precision improved by cutting the reference surface (301), and is electrolessly plated with nickel, can be appropriately used. By doing so, a reference surface (301) with high flatness and sliding characteristics (low frictional resistance to the sheet) is obtained, thereby realizing an improvement in the precision of the inclination movement correction of the sheet (S).

[0045] In the inclined movement correction unit (55), as shown in FIGS. 10 and 11, a pressurizing mechanism (33), which is a third switching means, is provided to switch between a pressurized state in which a sheet can be fed while being fitted and supported in a nip (nip portion) between an inclined feed roller (32-n) and a driven roller (331-n) opposite the inclined feed roller (32-n), and a release state in which the pressurizing state is released. Additionally, the release state is not limited to a state where the nip portion is released, but also includes a case where the rollers are in contact with each other with a weak force compared to the force of the pressurizing state. Furthermore, the pressurizing state of the pressurizing mechanism (33) refers to a state in which at least one inclined feed roller (32) is in a pressurized state, and the release state of the pressurizing mechanism (33) refers to a state in which all inclined feed rollers (32) are in a release state. In addition, in this embodiment, "n" is a number numbered from the upstream inclined feed roller (32) and the upstream driven roller (331) with respect to the sheet feed direction (V), for example, the inclined feed roller (32-1) means the inclined feed roller (32) placed at the uppermost (n=1). That is, in the inclined movement correction unit (55) of this embodiment, a plurality of pairs of driven rollers (331-n) and a pressurizing mechanism (33) are arranged in such a state that the inclined feed roller (32-n) shown in FIG. 10 and FIG. 11 can be replaced with any one of the inclined feed rollers (32-1, 32-2, and 32-3).

[0046] As shown in parts (a) and (b) of FIG. 10, the pressure mechanism (33) includes an arm member (332), a link member (333), a pressure gear (334), a pressure spring (335), and a driven roller pressure motor (Mk-n). The driven roller (331-n) is rotatably supported by the arm member (332) around a driven (driven) axis, and the driven roller (331) can move in a direction that approaches the inclined feed roller (32-n) or separates from the inclined feed roller (32-n) by the oscillation of the arm member (332). In this embodiment, the driven roller (331-n) rotates along the sheet feed direction (V) around an axis extending in the width direction, but a configuration in which the driven roller (331-n) is positioned on an axis parallel to the corresponding inclined feed roller (32-n) may also be adopted. The arm member (332) is connected to the pressure gear (334) through the pressure spring (335) and the link member (333). The pressure gear (334) is connected to the output shaft of the driven roller pressure motor (Mk-n), which is the driving source.

[0047] As shown in part (a) of FIG. 11, in the pressurized state, when the pressurizing gear (334) rotates counterclockwise in the drawing, the arm member (332), which is tensioned by the pressurizing spring (335), oscillates counterclockwise around the oscillating axis (332a). By doing so, a pressurized state is formed in which the driven roller (331-n) presses against the inclined feed roller (32-n). Meanwhile, as shown in part (b) of FIG. 11, in the released state, the pressurizing gear (334) rotates clockwise in the drawing to press the link member (333), and the link member (333) oscillates the arm member (332) clockwise. Accordingly, the driven roller (331-n) is separated from the inclined feed roller (32-n), or at least a separation state is formed in which the contact pressure of the driven roller (331-n) to the inclined feed roller (32-n) is smaller than the contact pressure in the pressurized state.

[0048] The driven roller pressure motor (Mk-n) is a stepping motor, and by controlling the rotation angle of the pressure gear (334), the amount of extension of the pressure spring (335) in the pressure state can be changed. That is, the pressure mechanism (33) of the present embodiment can perform both switching between the pressure state and the release state and changing the pressure force in the pressure state.

[0049] <Configuration of Seat Position Detection Sensor>

[0050] Next, with reference to FIG. 12, the configuration of the sheet position detection sensor (60) as a detection means of the present embodiment will be described. FIG. 12 is a perspective view illustrating the placement position of the sheet position detection sensor (60) in the feed unit (50). The sheet position detection sensor (60) is equipped with an optical element such as a CIS (Contact Image Sensor) and is positioned on the same side as the reference member (31) and offset in the width direction with respect to the center of the sheet in the width direction orthogonal to the sheet feed direction (V). This is because the position of the side end of the sheet that the sheet contacts the reference member (31) is detected, and the influence of variations in the cutting direction of the sheet in the width direction can be reduced. That is, in the present embodiment, the distance (L) before tilt movement correction can be detected with high precision.

[0051] <Slide configuration of the feed roller>

[0052] Next, with reference to FIGS. 13 to 15, the driving configuration of the feed roller (34-4) in the present embodiment and the configuration of the sliding mechanism (600) as a first feed roller moving part that slides the feed roller (34-4) will be described. FIG. 13 is a schematic perspective view of a roller driving mechanism (800) that drives the feed roller (34-4). FIG. 14 is a schematic perspective view of a sliding mechanism (600) that slides the feed roller (34-4). Part (a) of FIG. 15 is an enlarged perspective view of a pressure release mechanism (700) that sets the feed roller (34-4) to a pressure state or a release state, and part (b) of FIG. 15 is a cross-sectional view of the pressure release mechanism (700).

[0053] The feed roller (34-4) is rotatably driven by a roller driving mechanism (800) and configured to be movable in a width direction perpendicular to the sheet feed direction by a sliding mechanism (600) while the sheet is fitted and supported. Additionally, the feed roller (34-4) is configured to switch between a pressurized state in which the sheet is fitted and supported between the rollers constituting the feed roller (34-4) and a separated state in which the rollers are spaced apart from each other. Furthermore, the release state of the feed roller (34-4) is not limited to a state where the nip portion is released, but includes cases where the rollers come into contact with each other with a weaker force compared to the force in the pressurized state. The feed roller (34-4) is composed of an upper roller (401) and a lower roller (402) (see FIG. 15). The lower roller (402) is rotatably supported by the frame (201) (see FIG. 15), and the upper roller (401) is rotatably supported by the pressure arm (405) (see FIG. 14). The pressure arm (405) is rotatably fixed by an axis (201a) formed on the frame (201) (see FIG. 14). The upper roller (401) is pressed against the lower roller (402) by a tension spring (407). Additionally, a roller gear (412) is fixed to one end of the lower roller (402) to transmit drive from the roller drive mechanism (800) to the lower roller (402) (see FIG. 13).

[0054] A roller drive mechanism (800) for rotating a feed roller (34-4) is configured to include a sliding roller drive motor (801), drive gears (802 and 803), and a roller gear (412), as shown in FIG. 13. The sliding roller drive motor (801) is fixed to the frame (201), and the drive of the sliding roller drive motor (801) is transmitted to the roller gear (412) through the drive gears (802 and 803). Additionally, regarding the drive gear (803), the tooth surface of the drive gear (803) is formed at a length (d) longer than the reciprocating width of the roller gear (412) so that the coupling between the drive gear (803) and the roller gear (412) is maintained. The drive gears (802 and 803) are each freely rotatably fixed to fixed axes (201b and 201c) of the frame (201). The sliding roller drive motor (801) rotates in the direction of arrow A1 in FIG. 13. A stepping motor is used as the sliding roller drive motor (801). With this configuration, the drive of the sliding roller drive motor (801) is transmitted to the roller gear (412) and the feed roller (34-4) rotates.

[0055] A sliding mechanism (600), which is a moving means for moving the feed roller (34-4) in a width direction perpendicular to the sheet feed direction, includes a slide motor (601) that is fixed to a motor support plate (603) by a screw while the slide motor (601) is fixed to a motor table (602), as shown in FIG. 14. A pulley support plate (604) is fixed by a screw above the motor support table (603) through which the slide motor (601) is interposed. Pulley tables (605 and 606) are fixed to the pulley support plate (604). Pulley shafts (607 and 608) are each rotatably fixed to the pulley tables (605 and 606). Pulleys (609 and 610) are fixed to the pulley shaft (607), and a pulley (611) is fixed to the pulley shaft (608) (see FIG. 13). Additionally, a pulley (612) is fixed to the free end of the output shaft of the slide motor (601). A timing belt (613) is extended between the pulley (609) and the pulley (612), and a timing belt (614) is extended between the pulley (610) and the pulley (611).

[0056] At the end of the lower roller on the side of the roller gear (412), a holder (415) is rotatably supported by a bearing. The holder (415) is equipped with a sensor flag (416) that detects the groove position in the width direction of the upper roller (401) and lower roller (402) of the feed roller (34-4). When the upper roller (401) and lower roller (402) of the feed roller (34-4) are in the groove position, the sensor flag (416) is detected by a sensor (615) provided on the pulley support plate (604). Additionally, the holder (415) is fixed to the timing belt (614) by a stopper (616) and a screw. With this configuration, the timing belt (614) rotates by driving the slide motor (601), and the lower roller (402) of the feed roller (34-4) reciprocates in the width direction perpendicular to the sheet feed direction by the rotation of the timing belt (614). Additionally, the upper roller (401) of the feed roller (34-4) is coupled to the lower roller (402) by an interlocking member and reciprocates together with the lower roller (402) in the width direction perpendicular to the sheet feed direction. In this embodiment, before the leading edge of the sheet reaches the feed roller (34-4), the position of the sheet end in the width direction detected by the CIS (60) is detected. Then, based on the detection result, the slide motor (601) is driven so that the feed roller (34-4) moves in the width direction.

[0057] A pressure release mechanism (700), which is a second switching means for moving the upper roller (401) and lower roller (402) of the feed roller (34-4) toward each other or away from each other, includes a pressure release shaft (701) positioned on the frame (201) as shown in part (a) of FIG. 15. Additionally, the pressure release mechanism (700) is configured to include cams (702 and 703) (see FIG. 15 (b)) fixed to the pressure release shaft (701). As shown in FIG. 15 (b), deep groove ball bearings (702a and 703a) are pressed into the cams (702 and 703) at positions eccentric from the rotation center of each cam (702 and 703). Additionally, as shown in part (a) of FIG. 15, a gear (702b) is provided in the cam (702), and the drive of the release motor (704) is transmitted through the cam (702), thereby causing the release shaft (70) to rotate.

[0058] Additionally, a deep groove ball bearing (702a) is positioned so that it can contact the pressure arm (405), and when the release shaft (701) completes one full rotation, the deep groove ball bearing (702a) resists the pressure of the spring (407) and shifts the pressure arm (405). In this way, as the pressure arm (405) oscillates, the upper roller (401) and the lower roller (402) can come into contact with each other and separate once each. Additionally, a pressure arm is provided on the side where the deep groove ball bearing (703a) is provided with respect to the axial direction of the release shaft (701). Additionally, a sensor flag (703b) is provided on the cam (703) (see part (b) of FIG. 15). The phase of the pressure release shaft (701) is determined by detecting the sensor flag (703b) by the sensor (706) fixed to the sensor support plate (705) fixed to the frame (201), and the rotation of the pressure release motor (704) is controlled according to the phase of the pressure release shaft (701). In addition, the phase of the cams (702 and 703) is determined so that the sensor flag (703b) blocks the sensor (706) when the upper roller (401) and the lower roller (402) of the feed roller are in contact with each other.

[0059] <Control Configuration of the Registration Department>

[0060] Next, the control configuration of the registration unit (5) will be described with reference to FIG. 16. As shown in FIG. 16, the operation of the registration unit (5) is controlled by a controller (600A) mounted on the printer (1). The controller (600A), which is an example of a control means of the present embodiment, includes a CPU (601) as a computing means, a RAM (602) and a ROM (603) as storage means, and an interface (I / O) (604) for an external device or network.

[0061] The CPU (601) performs control based on information input through the control unit (400) as a user interface or detection signals from the aforementioned pre-registration sensor (P) and pre-registration sensor (Q). The detection signals from the pre-registration sensor (P) and pre-registration sensor (Q) are input to the CPU (601) through the AD converters (605P and 605Q), respectively. Additionally, the detection signal from the seat position detection sensor (60) is input to the CPU (601) through the AD converter (60C). The CPU (601) loads and executes a program stored in the ROM (603), etc. The CPU (601) drives and controls the motor (Ms, 801, 701, Md, 104d, Mk-n, 901, etc.), which is an actuator of the registration unit (5), through drivers (606d, 607a, 607b, 607c, 608a, 608b, and 609n). By doing so, the steps of the control method described according to the flowchart of FIG. 17 can be executed. Additionally, the driven rollers (331-n) are arranged in a number (n) corresponding to the inclined feed rollers (32-n), and the CPU (601) can independently control the presence or absence of pressure and the magnitude of the pressure applied by the driven rollers (331-n) to each inclined feed roller (32).

[0062] Control method for the registration section

[0063] Next, the sheet feeding operation in the registration unit (5) in Embodiment 1 is explained according to the flowchart of FIG. 17. Additionally, during the execution of the flowchart of FIG. 17, the inclined feeding roller is driven to rotate continuously. Furthermore, as previously mentioned, the control of the sheet feeding operation in the registration unit (5) in this embodiment is realized by executing a program stored in a storage means such as ROM (603) after it has been deployed to RAM (602). Accordingly, the steps included in the flowchart of FIG. 17 are executed by each part of the registration unit (5) under the control of the CPU (601). Additionally, in the flowchart of FIG. 17, the feeding roller (34-4) is referred to as a "sliding roller" as the first feeding roller and is explained.

[0064] First, an image formation operation is initiated (S01) with information such as profile information, which is information indicating the characteristics of the sheet (S) to be formed, and the size and number of sheets (S) being input through the control unit (400) or the interface (I / O) (604). Here, the profile information of the sheet (S) acquired by the CPU (601) through the control unit (400) or the interface (I / O) (604) is information indicating the characteristics of the sheet (S), such as basis weight, rigidity, surface roughness, and material. Then, based on the information input in S01, the pressure (pressure force) of each inclined feed roller (32) is determined (S02). However, the pressure in this embodiment is the pressure force of the driven roller (331-n) for the inclined feed roller (32-n), and is a value determined for each inclined feed roller (32-1, 32-2, and 32-3) based on information previously stored in the ROM (603), etc. In this embodiment, the magnitude of the pressure is a value set according to the basis weight of the sheet (S) so that the sheet (S) can be stably fed regardless of the type of sheet (S), for example. Based on the pressure determined in this way, the pressure of each inclined feed roller (32) is initiated, so the inclined feed roller (32) becomes a pressured state (S03).

[0065] After that, when an image formation operation by the image forming unit (PY to PK) is initiated (S04), based on the timing of the start of the image formation operation, the delay time for the start of feeding the sheet (S) is counted (S05), and then the sheet (S) is fed from the feeding cassette (51) (S06). During the process until the sheet (S) fed from the feeding cassette (51) reaches the inclined feeding roller (32), the position of the end of the sheet (S) in the width direction orthogonal to the sheet feeding direction is detected by the sheet position detection sensor (60) (S07). Then, the CPU (601) determines the position of the end of the sheet (S) relative to the reference surface (301) of the reference member (31) based on the position of the end of the sheet (S) detected in S07.

[0066] Here, regarding the width direction, we consider the case where the end of the sheet (S) is closer to the reference plane (301) of the reference member (31) than the inclined feed roller (32) (see part (a) of FIG. 5) and the case where the end of the sheet (S) is further from the inclined feed roller (32) than the inclined feed roller (32) (see part (b) of FIG. 5). When the sheet (S) is in the positional relationship shown in part (a) of FIG. 5, the sheet (S) comes into contact with the reference plane (301) at a position between the inclined feed roller (32-1) and the inclined feed roller (32-2). On the other hand, when the sheet (S) is in the positional relationship shown in part (b) of FIG. 5, in order for the sheet (S) to come into contact with the reference plane (301), it is necessary to feed the sheet (S) by the inclined feed roller (32) over a length longer than the length when the sheet (S) is in the positional relationship shown in part (a) of FIG. 5. Accordingly, with respect to the width direction, as the position of the end of the sheet (S) relative to the reference plane (301) of the reference member (31) changes, the feeding speed of the sheet (S) when the sheet (S) is fed along the reference plane (301) also changes (see FIG. 6).

[0067] Meanwhile, in this embodiment, before reaching the inclined feed roller (32) at the leading edge of the sheet (S), the sheet (S) is moved in the width direction according to the position of the end of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction. Accordingly, the travel distance of the sliding roller (feed roller (34-4)) in the width direction is determined according to the position of the end of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction (S08). For example, if the position of the end of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is at the position shown in part (a) of FIG. 5, the travel distance (12 mm) of the sliding roller in the width direction is determined such that the distance between the end of the sheet (S) and the reference plane (301) in the width direction is 4 mm. Meanwhile, regarding the width direction, if the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) is at the position shown in part (b) of FIG. 5, the travel distance (42 mm) of the sliding roller in the width direction is determined such that the distance between the end of the sheet (S) and the reference plane (301) in the width direction is 4 mm. In this way, when the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is at the first position (e.g., part (a) of FIG. 5), the sliding roller is moved by the first distance in the width direction. Meanwhile, when the end position of the sheet (S) relative to the reference plane (301) is at the second position, which is further from the reference plane (301) than the first position (e.g., part (b) of FIG. 5), the sliding roller is moved by the second distance in the width direction, which is longer than the first distance. In this way, the present embodiment reduces the variation in the end position of the sheet (S) relative to the reference surface (301) of the reference member (31) in the width direction. Specifically, the position where the end of the sheet (S) comes into contact with the reference surface (301) is determined between the second inclined feed roller (32-2) and the third inclined feed roller (32-3) in the sheet feed direction.In addition, the target value of the distance between the reference plane (301) and the end of the sheet (S) was set to 4 mm in the above case, but it was found by experiment that the distance is optimally set to a range of 4 mm to 10 mm when considering the degree of inclination movement of the sheet (S) being fed in the sheet feeding direction.

[0068] Then, when the sheet (S) being delivered to the sliding roller is detected by the pre-registration sensor (P) (S09 / Y), the stop delay time is counted (S10). When the stop delay time has elapsed, the drive of the feed roller drive motor (Md) and the drive of the sliding roller drive motor (801) are stopped (S11). By stopping the drive of the feed roller drive motor (Md) and the drive of the sliding roller drive motor (801), the feed of the sheet (S) is stopped while the sheet (S) is held in place by the sliding roller. Additionally, in S09, if the pre-registration sensor (P) does not detect the sheet (S) even after a predetermined time has elapsed since the start of the feed of the sheet (S) (S09 / N), a screen indicating a sheet jam is displayed on the control unit (400) (S24), and the operation is terminated.

[0069] Additionally, at S11, the driving of the feed roller drive motor (Md) and the driving of the sliding roller drive motor (801) are stopped, and then the fitting support of the sheet (S) by the feed roller (34-3, 34-2, and 34-1), which is a third feed roller positioned upstream of the sliding roller, is released (S12). Then, the sliding roller is moved in the width direction according to the moving distance of the sliding roller in the width direction determined at S08 (S13). When the sliding roller is moved in the width direction, the fitting support of the sheet (S) by the feed roller (34-3, 34-2, and 34-1) is released, and thus the load on the sheet (S) due to the sliding movement can be reduced.

[0070] After that, a restart delay time is counted in accordance with the progress of the image formation operation (step S14), and the driving of the sliding roller drive motor (801) is resumed (step S15). Since the restart timing of the sliding roller drive motor (801) is adjusted in accordance with the image formation operation, the time variation until the sheet (S) reaches the pre-registration sensor (P) is absorbed. After that, a delay time for releasing the pressure state of the sliding roller is counted (step S16), and since the upper roller (401) and the lower roller (402) are separated from each other, the sliding roller becomes separated (step S17). As a result, the clamping support state of the sheet (S) by the sliding roller is released, and a contact alignment operation is initiated to correct the inclination movement of the sheet (S) by bringing the sheet (S) into contact with the reference member (31).

[0071] When the pressure state of the sliding roller is released, the sheet (S) begins to move in an inclined direction toward the sheet feeder so as to approach the reference member (31) by the feeder force received from the inclined feeder roller (32). That is, the sheet (S) is fed (inclined) along the tangential direction of each inclined feeder roller (32) inclined toward the sheet feeder direction, and is displaced toward the reference plane (301) of the reference member (31). After the pressure of the sheet (S) by the inclined feeder roller (32) begins in S03, if the registration-pre-sensor (Q) detects the leading edge of the sheet (S) (S18 / Y), a delay time for releasing the pressure state of the inclined feeder roller is counted (S19). Then, after the delay time of S19 has elapsed, the pressure state of the inclined feeder roller (32) is released (S20). This delay time is set so that the inclined feed roller (32) is released after the leading edge of the sheet (S) enters the nip of the registration roller pair (7). Additionally, if the registration-pre-sensor (Q) does not detect the sheet (S) within a predetermined time, a screen indicating a sheet jam is displayed on the control unit (400) (step S24), and the operation is terminated.

[0072] When a sheet (S) is delivered to the registration roller pair (7) of the present embodiment, the registration roller pair (7) moves in the width direction while feeding the sheet (S). As a result, the center position of the sheet (S) in the width direction, which is orthogonal to the sheet feeding direction, is aligned with the center position of the image formed by the image forming unit (PY to PK). When the sheet (S) is sent to the secondary transfer unit (T), the value of the number (K) is incremented by a counter that manages the number of remaining sheets (S) to be image formed (step S22). If the number (K) of the remaining sheets (S) is not 0, that is, if there are sheets to be image formed remaining (step S23 / N), the aforementioned operation (steps S03 to S23) is repeated. If the number (K) of the remaining sheets (S) is 0 (step S23 / Y), it is determined that the image formation operation is completed, and the operation is terminated.

[0073] In this way, in the present embodiment, before the leading edge of the sheet (S) reaches the inclined feed roller (32), the sheet (S) is moved in the width direction according to the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction. By doing so, the variation in the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction can be reduced. As a result, the variation in the feed time until the inclined feed roller feeds the sheet (S) at an angle and the leading edge of the sheet (S) reaches the registration roller pair can be reduced, and thus the productivity of the sheet feed device (image forming device) can be improved.

[0074] [Embodiment 2]

[0075] <Composition of the Registration Department>

[0076] In Embodiment 1, a configuration was described in which a sliding mechanism (600) is provided on a feed roller (34-4) positioned at the downstream side of the feed section (50) in the sheet feed direction. In this embodiment, a configuration is described in which sliding mechanisms (600a and 600b) are respectively provided on feed rollers (34-4 and 34-3) on the downstream side of the feed section (50) in the sheet feed direction. FIG. 18 is a schematic diagram of the registration section (5) of this embodiment. The registration section (5) of this embodiment has the same configuration as the registration section (5) of Embodiment 1, except that a sliding mechanism (600b) is provided on the feed roller (34-3). In addition, since the configuration of the sliding mechanism (600a) as the first feed roller moving part and the sliding mechanism (600b) as the second feed roller moving part is the same as the configuration of the sliding mechanism (600) of Embodiment 1, a redundant description is omitted. In addition, the sliding mechanism (600) may be provided on all feed rollers (34) constituting the feed part (50).

[0077] <Control Configuration of the Registration Department>

[0078] Next, with reference to FIG. 19, the control configuration of the registration unit (5) of the present embodiment will be described. As shown in FIG. 19, the operation of the registration unit (5) is controlled by a controller (600A) mounted on the printer (1). In addition, in the control configuration of the registration unit (5) in the present embodiment, components identical to those in Embodiment 1 are indicated by the same reference numerals, and redundant descriptions are omitted. The CPU (601) drives and controls the motors (Ms, 801a, 801b, 701a, 701b, Md, 104d, Mk-n, 901a, 901b, etc.) which are actuators of the registration unit (5) through drivers (606d, 607a, 607b, 607c, 608a, 608b, and 609-n). Accordingly, the steps of the control method described according to the flowchart of FIG. 20 can be executed.

[0079] Control method for the registration section

[0080] Next, the sheet feeding operation in the registration unit (5) in Embodiment 2 is explained according to the flowchart of FIG. 20. Additionally, during the execution of the flowchart of FIG. 20, the inclined feeding roller is continuously rotated. Furthermore, as previously mentioned, the control of the sheet feeding operation in the registration unit (5) in this embodiment is realized by executing a program stored in a storage means such as ROM (603) after it has been deployed to RAM (602). Accordingly, the steps included in the flowchart of FIG. 20 are executed by each part of the registration unit (5) under the control of the CPU (601). Additionally, in the flowchart of FIG. 20, the feeding roller (34-4) is referred to as the "first sliding roller" and the feeding roller (34-3) is referred to as the "second sliding roller" for explanation. In this embodiment, the first feeding roller is the feeding roller (34-4), and the third feeding roller is the feeding roller (34-3). In addition, in the flowchart of FIG. 20, steps identical to the sheet feeding operation step in the registration unit (5) of Embodiment 1 are indicated by the same reference number or symbol as FIG. 17, and redundant descriptions are omitted.

[0081] In the flowchart of FIG. 20, the steps up to S09 are the same as the steps of Embodiment 1. In this embodiment, the explanation begins with step S101. When the sheet (S) delivered to the sliding roller is detected by the pre-registration sensor (P) (S09 / Y), a stop delay time is counted (S101). When the stop delay time has elapsed, the driving of the feed roller drive motor (Md) and the driving of the sliding roller drive motors (801a and 801b) are stopped (S111). By stopping the driving of the feed roller drive motor (Md) and the driving of the sliding roller drive motors (801a and 801b), the feeding of the sheet (S) is stopped while the sheet (S) is held by the first and second sliding rollers. In addition, in S09, if the pre-registration sensor (P) does not detect the sheet (S) even after a predetermined time has elapsed since the start of the delivery of the sheet (S) (S09 / N), a screen indicating a sheet jam is displayed on the control unit (400) (S24), and the operation is terminated.

[0082] Additionally, at S111, the driving of the feed roller drive motor (Md) and the driving of the sliding roller drive motors (801a and 801b) are stopped, and then the fitting support of the sheet (S) by the feed rollers (34-2 and 34-1), which are third feed rollers positioned upstream of the sliding roller, is released (S121). Then, the first sliding roller and the second sliding roller are moved in the width direction according to the moving distance in the width direction of the sliding roller determined at S08 (S131). When the sliding roller moves in the width direction, the fitting support of the sheet (S) by the feed rollers (34-2 and 34-1) is released, so the load on the sheet (S) due to the sliding movement can be reduced.

[0083] After that, a restart delay time is counted in accordance with the progress of the image formation operation (step S141), and then the driving of the sliding roller drive motors (801a and 801b) is resumed (step S151). Since the restart timing of the sliding roller drive motors (801a and 801b) is adjusted in accordance with the image formation operation, the variation in time until the sheet (S) reaches the pre-registration sensor (P) is absorbed. After that, a delay time for releasing the pressure state of each of the first and second sliding rollers is counted (step S16), and since the upper roller (401) and the lower roller (402) are separated from each other, the first and second sliding rollers become separated (step S171). By this, the fitting support state of the sheet (S) by the first sliding roller and the second sliding roller is released, and thus a contact alignment operation is initiated to correct the inclination movement of the sheet (S) by bringing the sheet (S) into contact with the reference member (31).

[0084] When the pressure state of the first and second sliding rollers is released, the sheet (S) begins to move in an inclined direction toward the sheet feeding direction to approach the reference member (31) by the feeding force received from the inclined feeding roller (32). That is, the sheet (S) is fed (inclined) along the tangential direction of each inclined feeding roller (32) inclined toward the sheet feeding direction, and is displaced toward the reference plane (301) of the reference member (31). Since the subsequent steps are similar to Embodiment 1, the description is omitted.

[0085] In addition, in this embodiment as well, similar to embodiment 1, before the leading edge of the sheet (S) reaches the inclined feed roller (32), the sheet (S) moves in the width direction according to the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction. By doing so, the variation in the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction can be reduced. As a result, the variation in the feed time until the inclined feed roller feeds the sheet (S) at an angle and the leading edge of the sheet (S) reaches the registration roller pair can be reduced, and thus the productivity of the sheet feed device (image forming device) can be improved. In addition, in this embodiment, since the sheet (S) moves while being supported by feed rollers (34-4 and 34-3), the sheet (S) can be moved quickly in the width direction even when a sheet with smooth surface characteristics and a sheet with a large basis weight are used.

[0086] [Embodiment 3]

[0087] In embodiments 1 and 2, when moving the sheet (S) in the width direction, among the rollers of the feed unit (50), the rollers other than the rollers that move the sheet (S) in the width direction while holding and supporting the sheet (S) are separated. In recent years, it has been desired for the printer (1) to accommodate sheets with extremely long sheet lengths in the sheet feed direction (long sheets). However, when moving a long sheet in the width direction, if a configuration is adopted in which the rollers other than the rollers that move the sheet (S) in the width direction while holding and supporting the sheet (S) are separated, the configuration of the printer (1) becomes complex and is likely to cause an increase in the size and cost of the sheet feed device. Therefore, in this embodiment, when the sheet fed through the registration unit (5) is a long sheet, the reference member (31) is moved in the width direction to suppress the variation of the distance (L) before the inclination movement correction (see FIG. 4).

[0088] As shown in FIG. 21, in the correction of the inclination movement of a sheet having a normal length as described in embodiments 1 and 2, it is necessary to feed multiple sheets (sheet S1, sheet S2, ...) simultaneously in contact with a reference member for high productivity. Therefore, when feeding a long sheet, even if one attempts to move the reference member (31) based on the detection result of the side end position of the long sheet, the reference member (31) cannot be slid due to the presence of the sheet (S1) that was fed earlier. Meanwhile, in this embodiment, depending on the length of the sheet feeding direction of the sheet fed through the feeding unit (50), either the movement of the feeding roller (34-4) or the movement of the reference member (31) is performed.

[0089] FIG. 21 illustrates an example in which the sliding mechanism (600) of Embodiment 1 is provided on the feed rollers (34-4 and 34-3). In addition to this example, a configuration in which the sliding mechanism (600) is provided only on the feed roller (34-4) may be adopted. In FIG. 23 and 24, assuming that the sliding mechanism (600) is provided on the feed roller (34-4), the feed roller (34-4) is referred to as a "sliding roller" for the description. Since tilt movement correction can be performed according to the steps of FIG. 24 even when the sliding mechanism (600) is provided on each feed roller (34-4 and 34-3), the configuration in which the sliding mechanism (600) is provided on the feed roller (34-4) is described as an example in this embodiment. In addition, since the configuration excluding the reference member moving mechanism (300) that moves the reference member (31) in the width direction is the same as embodiments 1 and 2, a redundant description is omitted.

[0090] <Composition of the reference member movement mechanism>

[0091] With reference to parts (a) and (b) of FIG. 22, the configuration of a reference member moving mechanism (300) as a contact surface moving part that moves a reference member (31) in the width direction will be described. As shown in part (a) of FIG. 22, the reference member moving mechanism (300) is provided with bearing stands (303A and 303B) fixed on a base part (300A). These bearing stands (303A and 303B) rotatably support a lead screw (304). As shown in part (b) of FIG. 22, a double row angular ball bearing (315) is fitted inside the bearing stand (303A). The angular ball bearing (315) is fixed to the lead screw (304) through two spacers (306) by means of a lock nut (307). Accordingly, when the lock nut (307) is tightened by a predetermined torque, the lead screw (304) is uniquely positioned relative to the bearing stand (303A) due to the backlash reduction effect of the angular ball bearing (315). Inside the bearing stand (303B), a deep groove ball bearing (308) is coupled with a predetermined gap. Additionally, the deep groove ball bearing (308) and the lead screw (304) are coupled with a predetermined gap, and a C-ring (309) is attached to the free end of the lead screw (304) to support the deep groove ball bearing (308).

[0092] A nut (310) is rotatably attached to the spline portion (304a) of the lead screw (304), and a bracket (311) to which a reference member (31) (see FIG. 21) can be connected is fixed to the nut (310). The lead screw (304) and the nut (310) are ball springs, and a ball is embedded within the nut (310). By this, the precision of the reference member (31) during movement and the reduction of noise are realized. In addition, a reference member slide motor (313) is connected to the free end (304b) of the lead screw (304) through a coupling (312), so that the misalignment of the rotation center between the reference member slide motor (313) and the lead screw (304) is absorbed. The reference member slide motor (313) is fixed to a motor support plate (314). By means of the reference member moving mechanism (300) configured in this way, the reference member (31) can slide in the width direction.

[0093] <Control Configuration of the Registration Department>

[0094] Next, with reference to FIG. 23, the control configuration of the registration unit (5) of the present embodiment will be described. As shown in FIG. 23, the operation of the registration unit (5) is controlled by a controller (600A) mounted on the printer (1). In addition, in the control configuration of the registration unit (5) of the present embodiment, components identical to those in embodiments 1 and 2 are indicated by the same reference number or symbol, and redundant descriptions are omitted. The CPU (601) drives and controls the motors (Ms, 801, 701, Md, 104d, Mk-n, 901, 313, etc.), which are actuators of the registration unit (5), through drivers (606d, 607a, 607b, 607c, 608a, 608b, 609-n, and 313c). By doing so, the steps of the control method described along the flowchart of FIG. 24 can be executed.

[0095] Control method for the registration section

[0096] Next, the sheet feeding operation in the registration unit (5) in embodiment 3 is explained according to the flowchart of FIG. 24. Additionally, during the execution of the flowchart of FIG. 24, the inclined feeding roller is continuously rotated. Furthermore, as previously mentioned, the control of the sheet feeding operation in the registration unit (5) in this embodiment is realized by executing a program stored in a storage means such as ROM (603) after it has been deployed to RAM (602). Accordingly, the steps included in the flowchart of FIG. 24 are executed by each part of the registration unit (5) under the control of the CPU (601). Additionally, in the flowchart of FIG. 24, the feeding roller (34-4) is referred to as a "sliding roller" for explanation. In addition, in the flowchart of FIG. 24, steps identical to the sheet feeding operation steps in the registration section (5) of embodiments 1 and 2 are indicated by the same reference numbers or symbols as FIG. 17 and FIG. 20, and redundant descriptions are omitted.

[0097] In the flowchart of FIG. 24, the steps up to S11 are the same as in Embodiment 1. In this embodiment, the explanation begins with step S31. At S11, the driving of the feed roller drive motor (Md) and the driving of the sliding roller drive motor (801) are stopped, and based on the information obtained in S01, the CPU (601) determines whether the length of the sheet in the sheet feed direction is 762 mm or less (S31). If the length of the sheet in the sheet feed direction is 762 mm or less (S31 / Y), the gripping support of the sheet (S) by the feed rollers (34-3, 34-2, and 34-1) as third feed rollers positioned upstream of the sliding roller is released (S32). Then, the sliding roller is moved in the width direction according to the travel distance in the width direction of the sliding roller determined in S08 (S33). When the sliding roller moves in the width direction, the fitting support of the sheet (S) by the feed rollers (34-3, 34-2, and 34-1) is released, and thus the load on the sheet (S) due to the sliding movement can be reduced.

[0098] After that, a restart delay time is counted in accordance with the progress of the image formation operation (step S34), and the driving of the sliding roller drive motor (801) is resumed (step S35). Since the restart timing of the sliding roller drive motor (801) is adjusted in accordance with the image formation operation, the time variation until the sheet (S) reaches the pre-registration sensor (P) is absorbed. After that, a delay time for releasing the pressure state of the sliding roller is counted (step S36), and since the upper roller (401) and the lower roller (402) are separated from each other, the sliding roller becomes separated (step S37). As a result, the clamping support state of the sheet (S) by the sliding roller is released, and a contact alignment operation is initiated to correct the inclination movement of the sheet (S) by bringing the sheet (S) into contact with the reference member (31).

[0099] Meanwhile, if the length of the sheet in the sheet feed direction is longer than 762 mm (S31 / N), the reference member (31) is moved in the width direction by a distance equal to the distance traveled in the width direction of the sliding roller determined in S08 (S38). After that, the sliding roller and the feed roller (34) are separated (S39), and thus the seated support state of the sheet (S) in the feed section (50) is released, and then a contact correction operation is initiated to correct the inclination movement of the sheet (S) by bringing the sheet (S) into contact with the reference member (31). Since the subsequent steps are similar to embodiments 1 and 2, the description is omitted.

[0100] In this embodiment, when the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) is the position shown in part (a) of FIG. 5, the travel distance (12 mm) of the sliding roller or reference member (31) in the width direction is determined such that the distance from the end of the sheet (S) to the reference plane (301) in the width direction is 4 mm. Meanwhile, when the end position of the reference member (31) relative to the reference plane (301) is the position shown in part (b) of FIG. 5, the travel distance (42 mm) of the sliding roller or reference member (31) in the width direction is determined such that the distance from the end of the sheet (S) to the reference plane (301) in the width direction is 4 mm. In this way, when the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is a third position (e.g., part (a) of FIG. 5), the reference member (31) is moved in the width direction by a third distance. Meanwhile, when the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is a fourth position further from the third position (e.g., the position in part (b) of FIG. 5), the reference member (31) is moved in the width direction by a fourth distance longer than the third distance. Additionally, when the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is a fifth position (e.g., part (a) of FIG. 5), the reference member (31) is moved in the width direction by a fifth distance. Meanwhile, if the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is a sixth position that is further away than the fifth position (e.g., the position of part (b) of FIG. 5), the sliding roller is moved in the width direction by a sixth distance that is longer than the fifth distance. In this embodiment, the variation in the end position of the sheet (S) relative to the reference plane (301) of the reference member (31) in the width direction is reduced in the manner described above.

[0101] In this way, in the present embodiment, when the length of the sheet in the sheet feeding direction is shorter than the length of the registration section (5) in the sheet feeding direction (e.g., 762 mm or less), the feeding roller (34-4) moves in the width direction. On the other hand, when the length of the sheet in the sheet feeding direction is equal to the length of the registration section (5), a transition occurs in which the reference member (31) moves in the width direction. Therefore, even when feeding a long sheet, there is no need to provide a configuration in which the rollers of the feeding section (50) are spaced apart from each other over the entire length of the sheet, thereby avoiding complexity in the configuration of the printer (1) and increasing the size of the printer (1).

[0102] <Other embodiments>

[0103] In embodiments 1 to 3, a configuration in which the registration unit (5) is provided upstream of the secondary transfer unit (T) of the printer (1) is described. In addition to this configuration, a configuration similar to the registration unit (5) can also be installed in a post-printing device that performs post-processing such as punching or stapling on a sheet, for example.

[0104] In addition, the present invention may also be realized in a process in which a program realizing one or more functions of the above-described embodiment is supplied to a system or device through a network or a recording medium, and subsequently, one or more processors of a computer in the system or device load and execute the program. In addition, the present invention may also be realized by a circuit (e.g., an ASIC) realizing one or more functions.

[0105] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be interpreted in the broadest sense to include structures and functions equivalent to all such variations.

Claims

Claim 1 A sheet feeding device comprising: a first feeding roller pair configured to feed the sheet without changing the angle formed by the direction along the side edge of the sheet and the predetermined direction, regardless of the angle formed by the direction along the side edge of the sheet when the sheet reaches the first feeding roller pair; and a reference member provided downstream of the first feeding roller pair with respect to the sheet feeding direction and extending in the sheet feeding direction, wherein the reference member includes a contact surface in which the side edge of the sheet with respect to the width direction of the sheet can contact, and the contact surface extends in the predetermined direction. A sheet feeding device comprising: an inclined feeding roller configured to feed the sheet at an angle by contacting the sheet in an angled direction relative to the sheet feeding direction so that the sheet approaches the contact surface in the width direction of the sheet towards the downstream side of the sheet feeding direction; a second feeding roller pair configured to feed the sheet fed by the inclined feeding roller; a detection means provided upstream of the first feeding roller pair relative to the sheet feeding direction and configured to detect the position of a side edge portion of the sheet; and a controller configured to control the movement of the first feeding roller pair in the width direction of the sheet, wherein, before the sheet is fed at an angle by the inclined feeding roller, the controller causes the first feeding roller pair to move the sheet to a predetermined position in the width direction of the sheet based on the detection result of the detection means. Claim 2 A sheet feeding device according to claim 1, wherein detection of the sheet in the width direction by the detection means is performed before the leading edge of the sheet reaches the first feeding roller pair. Claim 3 A sheet feeding device according to claim 1 or 2, wherein the inclined feeding roller comprises a first inclined feeding roller, a second inclined feeding roller, and a third inclined feeding roller in this order, facing downstream in the sheet feeding direction at a position overlapping with the contact surface when viewed in the width direction of the sheet, and the sheet fed to the predetermined position by the first feeding roller pair has its leading end contacting the contact surface at its side end after reaching the second inclined feeding roller in the sheet feeding direction. Claim 4 A sheet feeding device according to claim 1, further comprising: a third feeding roller pair provided adjacent to and upstream of the first feeding roller pair in the sheet feeding direction and configured to feed the sheet; and a first switching means capable of moving the third feeding roller pair between a fitting support state in which the third feeding roller pair supports the sheet and a separation state in which the nip portion of the third feeding roller pair is released, wherein the controller controls the third feeding roller pair to be moved between the fitting support state and the separation state by the first switching means, and when the first feeding roller pair is moved in the width direction of the sheet, the controller causes the first switching means to switch the third feeding roller pair from the fitting support state to the separation state and then causes the first feeding roller pair to move in the width direction of the sheet. Claim 5 In paragraph 4, the detection means is a contact image sensor, and the sheet feeding device detects a side end of the sheet on one side where the contact surface is positioned with respect to the feeding centerline of the sheet fed by the third feeding roller pair. Claim 6 A sheet feeding device according to claim 5, further comprising a guide member configured to guide the sheet fed by the third feeding roller pair, wherein the contact image sensor is fixed to the guide member and detects the side edge of the sheet at a different position between when the width of the fed sheet in the width direction is a first width and when the width of the fed sheet is a second width wider than the first width. Claim 7 A sheet feeding device according to claim 4, further comprising a second switching means capable of moving the first feeding roller pair between a fitting support state in which the first feeding roller pair fits and supports the sheet and a separation state in which the nip portion of the first feeding roller pair is released, wherein the controller controls the second switching means, and when the sheet is inclined toward the contact surface by the inclined feeding roller, the controller controls the second switching means to switch the state of the first feeding roller pair from the fitting support state to the separation state and then cause the inclined feeding roller to inclinedly move the sheet. Claim 8 A sheet feeding device according to claim 7, wherein the sheet is inclinedly fed by the inclined feeding roller when the sheet is in a state of rotating while in contact with the inclined feeding roller and when the state of the nip portion of the first feeding roller pair is switched from the insertion support state to the separation state by the second switching means. Claim 9 A sheet feeding device according to claim 1, wherein the predetermined position is positioned between the contact surface and the inclined feed roller in the width direction of the sheet, and is positioned 4 mm apart from the contact surface in the direction toward the inclined feed roller. Claim 10 A sheet feeding device according to claim 7, further comprising: a moving means capable of moving the second feeding roller pair in the width direction of the sheet while the second feeding roller pair is in a state of fitting and supporting the sheet; and a third switching means capable of moving the inclined feeding roller between a fitting state in which the inclined feeding roller is fitting and supporting the inclined feeding roller and a separated state in which the inclined feeding roller is separated from the sheet, wherein the controller controls the moving means and the third switching means, and when the second feeding roller pair is moved in the width direction of the sheet by the moving means, the controller causes the third switching means to move the inclined feeding roller from the fitting and supporting state to the separated state. Claim 11 An image forming device comprising: a sheet feeding device according to claim 1; and an image forming means configured to form an image on a sheet fed by the sheet feeding device. Claim 12 A sheet feeding device according to claim 1, further comprising a third feeding roller pair provided adjacent to and upstream of the first feeding roller pair in the sheet feeding direction, wherein the third feeding roller pair is movable in the width direction of the sheet while supporting the sheet and is configured to feed the sheet, and the controller causes the third feeding roller pair to move the sheet in the width direction of the sheet in cooperation with the first feeding roller pair. Claim 13 A sheet feeding device according to claim 1, wherein the reference member is movable in the width direction of the sheet, and the controller controls the movement of the reference member in the width direction of the sheet, and when the length of the sheet being fed is a first length, before the sheet is inclined fed by the inclined feeding roller, the controller causes the first pair of feeding rollers to move the sheet to a predetermined position in the width direction of the sheet based on the detection result of the detection means, and when the length of the sheet being fed is a second length longer than the first length, the controller moves the reference member in the width direction of the sheet by a distance equal to the distance by which the first pair of feeding rollers moves the sheet to a predetermined position in the width direction of the sheet based on the detection result of the detection means. Claim 14 A sheet feeding device according to claim 13, wherein the second length is 762 mm in the sheet feeding direction.

Images