JP2011016649A - Sheet postprocessing apparatus and image forming system having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet postprocessing apparatus aligning sheets in a predetermined collection position, irrespective of the basis weight of the sheet and an image forming surface, when dropping and collecting the sheets onto a tray from a sheet discharge outlet.SOLUTION: This sheet postprocessing apparatus includes a tray means for collecting the sheets from the sheet discharge outlet and a sheet discharge rotating body for transferring the sheets carried out to this tray means toward a sheet end regulation means, and is configured to adjust the timing of moving this sheet discharge rotating body to an operation position engaging with the sheets from a withdrawal position above the tray corresponding to an image formation condition of the sheets.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet post-processing apparatus that performs post-processing such as paper binding on a sheet conveyed from an image forming apparatus such as a copying machine or a printer, and aligns the sheet conveyed on a tray at a predetermined position. Regarding improvements.

  In general, this type of sheet post-processing apparatus is provided with a processing tray at a paper discharge port of an image forming apparatus such as a copying machine or a printer, and a post-processing apparatus such as a stapler device, a punch device, or a stamp device is provided on the processing tray. It is widely known as an apparatus that performs post-processing by aligning and stacking sheets sent from an image forming apparatus.

  Conventionally, in such an apparatus, a processing tray is disposed downstream of the sheet discharge outlet, a stack tray is disposed downstream of the processing tray, and a sheet (bundle) post-processed by the processing tray is stored in the stack tray. Are known. For example, in Patent Document 1, a processing tray is disposed on the downstream side of the sheet discharge outlet and a processing tray is disposed on the downstream side. A structure is disclosed in which the front end portion is supported by a stack tray and the rear end portion of the sheet is supported by a processing tray (bridge support).

  In such an apparatus, it is necessary to dispose a sheet alignment mechanism on the processing tray for aligning the sheet carried out from the sheet discharge outlet with a predetermined restriction stopper position in a state where the sheet is bridge-supported between the two trays. For this reason, in Patent Document 1, a roller that can be raised and lowered is provided above the processing tray, and after the leading end of the sheet reaches the stack tray from the sheet discharge port, the roller is lowered from the upper retracted position to an operating position that contacts the sheet. Yes. The roller is rotated in the direction opposite to the paper discharge direction, and the trailing edge of the sheet carried out from the paper discharge port is abutted and aligned with the restriction stopper.

  Conventionally, when a sheet is carried out from a sheet discharge port to a tray having a step, a sheet discharge rotator such as a roller and a belt is provided on the tray so as to be movable up and down. At the timing of passing, the sheet moves from the retracted position to an operating position that engages with the sheet, and the sheet is abutted against the restriction stopper by the conveying force of the rotating body. In this case, the sheet discharge rotator is lowered to the operating position at the expected time when the rear end of the sheet passes through the sheet discharge port and is carried onto the tray based on the signal from the sheet detection sensor.

JP 2006-248686 A

  As described above, when the sheet carried out from the sheet discharge port is brought into contact with the restriction stopper on the tray and aligned, a sheet discharge rotating body that can be moved up and down is provided on the tray in front of the sheet discharge port. It is lowered to a position where it engages with the sheet at the timing when the end passes through the paper discharge port. Then, the rotation of the rotating body abuts and aligns the sheet with the restriction stopper on the tray. Conventionally, however, the timing for lowering the discharged sheet rotating body from the retracted position to the operating position is set to be constant regardless of the sheet conveyance state.

  However, in recent image forming apparatuses, it is necessary to use sheets with extremely wide properties (paper thickness, basis weight), and at the same time, the image forming conditions are diverse such as double-sided printing, single-sided printing, monochrome printing, and color printing. ing.

For example, a coating sheet is used in image formation of photographic data, and the surface frictional force when duplex printing is performed on this is extremely lower than when single-sided printing is performed on plain paper. In addition, extremely thick, for example, 200 to 300 gram paper may be used for image formation on a bookbinding cover.
On the other hand, ultra-thin paper sheets are used for image formation on Japanese paper and the like, and the properties of the sheets used with the multi-functionalization of the image forming system are widespread. In this case, if the timing for lowering the sheet discharge rotator onto the tray is set constant, the following problem occurs.

  FIG. 11 shows a problem caused by the conventional paper discharge timing. When the sheet S is carried out from the paper discharge port 100 onto the processing tray 101 and the stack tray 102 by the paper discharge roller 104, the leading end St extends from the paper discharge port to the processing tray. Subsequently, it is transferred in the order of the stack tray. After the front end St of the sheet reaches the forward / reverse rotation roller (paper discharge rotator) 103, the roller is lowered from the upper retracted position and engaged with the sheet, opposite to the paper discharge direction (arrow direction in the figure). It is rotating in the direction.

  With this operation, the sheet rear end Se is abutted against the restriction stopper 105 provided at the post-processing position of the processing tray 101 and is regulated. The timing at which the forward / reverse roller 103 is lowered from the retracted position to the operating position is detected, for example, by the sensor 106 provided on the upstream side of the sheet discharge port 100, and the sheet rear end Se is detected by the sheet discharge port 100. Has moved to the operating position after an estimated time of passing.

  In such a configuration, when the forward / reverse rotation roller 103 stops the sheet rear end Se against the restriction stopper 105, the sheet rear end Se does not reach the restriction position, and the sheet rear end Se is not in the restriction position. Overrun (causes the sheet to rise or break the tip). In particular, when the permissible range of the sheet is widened from thick paper to thin paper, or when image formation is performed on one-side monochrome printing and on both-side color printing, there is a great variation in the position regulation of the sheet trailing edge.

  Therefore, the peripheral speed of the discharge roller 104 and the drop (step) between the discharge outlet 100 and the processing tray 101 are set to the same condition, and the sheet basis weight (mass) and the image forming conditions such as the printing mode are varied. did. As a result, it was found that the single-sided monochrome printing landed farther than the double-sided color printing, and that the grounding (mass) of the sheet landed farther than when it was small.

As a result of this experiment, as shown in FIG. 5A, “when printed on one side of sheet (surface friction coefficient is smaller than both sides)” or “when basis weight (mass) of sheet is large” It was found that the sheet lands on the tray at a long distance (L1 in the drawing) from the discharge port.
On the other hand, as shown in FIG. 4B, when “printed on both sides of the sheet” or “the basis weight (mass) of the sheet is small”, the sheet is close to the tray from the discharge port. It was found to land on (L2 in the figure).

  The difference in the landing distance (L1> L2) of the sheet falling from the sheet discharge port onto the tray is caused by the difference in the inertial force of the sheet at the sheet discharge port. This is considered to be due to the fact that the inertia force of the sheet is large during single-sided printing with a large friction coefficient, and conversely when the thin paper sheet is weak, and during double-sided printing, the inertial force of the sheet is small.

  Accordingly, the present inventor has come up with the idea that the operation timing of lowering the forward / reverse rotation roller to the operating position varies depending on the image forming conditions such as the material of the sheet on which the image is formed and the image forming surface.

According to the present invention, when an image-formed sheet is dropped and accumulated on a tray from a paper discharge port, the sheet is correctly aligned at a predetermined accumulation position regardless of the basis weight (mass) of the sheet and the image forming surface (one side / both sides). The main problem is to provide a sheet post-processing apparatus that can handle such a situation.
Another object of the present invention is to form a compact and compact processing tray for aligning and stacking sheets in a post-processing apparatus in which a post-processing unit is built in the apparatus.

  In the present invention, the “image forming condition” refers to the sheet surface condition for image formation such as the basis weight (mass per unit area) of the image forming sheet, double-sided / single-sided, monochrome / color image. In order to achieve the above object, the present invention comprises a tray means for collecting sheets from the paper discharge port, and a paper discharge rotating body for transferring the sheet carried to the tray means toward the sheet end regulating means. It is characterized in that the timing for moving the discharge rotating body from the retracted position above the tray to the operating position for engaging the sheet can be adjusted according to the image forming conditions of the sheet.

  Further, the configuration will be described in detail. A paper discharge port (24), a tray unit (processing tray 28 described later) for stacking and stacking sheets sent from the paper discharge port, and an edge of the sheet provided on the tray unit A sheet end regulating means (rear end regulating stopper 30 described later), a sheet discharge rotating body (forward / reverse rotation roller 35 described later) for transferring a sheet carried on the tray means toward the sheet end regulating means, Lift support means (bracket 34 to be described later) that supports the discharge rotating body so as to be able to move up and down between an operation position (Fp) that contacts the sheet on the tray means and a retracted position (Wp) that is separated from the sheet; Elevating drive means (described later elevating motor MS) for driving the means, and elevating control means (described later control CPU 65) for controlling the elevating drive means.

  The elevating control unit is configured to be able to adjust the operation timing of moving the discharge rotating body from the retracted position to the operating position after the trailing edge of the sheet has passed through the discharge port according to the sheet image forming conditions. The tray means is provided with a post-processing means (37) for post-processing the accumulated sheets and a stack tray (29) for storing the post-processed sheets. The sheet discharge port is provided with a sheet sensor (a sheet discharge sensor S2 to be described later) that detects the front and rear ends of the sheets that are sequentially carried out, and the sheet discharge rotator is retracted with reference to a signal that the sensor detects the sheet rear end. It is configured to move from the position to the operating position.

  The present invention includes a tray unit for collecting sheets from the sheet discharge port, and a sheet discharge rotator for transferring the sheet conveyed to the tray unit toward the sheet end regulating unit. Since the timing for moving from the retracted position to the operating position for engaging the sheet can be adjusted in accordance with the image forming conditions of the sheet, the following effects can be obtained.

  The sheet carried out from the sheet discharge port is abutted and aligned with the sheet end regulating means by the sheet discharge rotator after its trailing end passes through the sheet discharge port. At this time, the landing position on the tray is shifted forward and backward in the paper discharge direction depending on the mass (basis weight) of the sheet and the printing area (one side or both sides). At this time, when the sheet transfer amount (distance) of the sheet discharge rotator is the same, the sheet end does not reach the regulation position, or the leading edge breaks due to overrun. On the other hand, according to the present invention, the timing at which the sheet is transferred toward the regulating stopper by the sheet discharge rotator is advanced or delayed according to the positional deviation amount, so that it is possible to always match the accurate position.

  Furthermore, the configuration for this is a simple structure by advancing the operation start timing of the sheet discharge rotating body when the image forming surface of the sheet carried out from the sheet discharge port is one side, and delaying the operation start timing when performing double-sided printing. It can be configured compactly. Similarly, the structure can be made compact with a simple structure by advancing earlier when the mass (basis weight) of the sheet carried out from the sheet discharge outlet is greater than or equal to a predetermined value and delaying when less than the predetermined value.

  As described above, according to the present invention, even when the landing position of the sheet falling on the tray means varies depending on the image forming conditions, the sheet trailing end can be surely reached the regulation stopper by changing the start timing of the sheet aligning operation of the sheet discharge rotating body. It is possible to make it.

1 is an explanatory diagram of an overall configuration of an image forming apparatus forming system according to the present invention. 2A and 2B are explanatory views of a paper discharge unit (sheet post-processing apparatus) in the system of FIG. 1, in which FIG. FIGS. 3A and 3B are explanatory views of a paper discharge structure of the paper discharge unit of FIG. 2, in which FIG. FIG. 3 is an explanatory diagram of a paper detection structure of a stack tray in the paper discharge unit of FIG. 2. FIGS. 3A and 3B are explanatory diagrams of a side alignment mechanism in the paper discharge unit of FIG. 2, in which FIG. 3A is an explanatory diagram of a bottom structure of a processing tray, and FIG. FIG. 3 is an explanatory diagram of a lifting mechanism for a sheet discharge rotating body in the sheet discharge unit of FIG. 2. FIG. 3 is an operation explanatory diagram illustrating a state of a sheet carried out from a sheet discharge port in the sheet discharge unit of FIG. 2. FIG. 3 is an operation explanatory diagram of a state in which a sheet is transferred to a trailing edge regulating stopper by a sheet discharge rotating body in the sheet discharge unit of FIG. 2. FIG. 2 is a block diagram showing a control configuration in the image forming system of FIG. 1. The flowchart which shows the operation state in the control structure of FIG. The sheet discharge state of the conventional sheet discharge device is shown, (a) shows the discharge state of the thick paper sheet, and (b) shows the discharge state of the thin paper sheet.

[Image forming system]
The image forming system shown in FIG. 1 includes an image forming apparatus A and a sheet post-processing apparatus B. The image forming apparatus A forms an image based on image data designated on the sheet, and places a sheet on the paper discharge port. It is configured to be carried out. The sheet post-processing apparatus B receives the image-formed sheet from the paper discharge port, aligns the sheet at a predetermined post-processing position, performs post-processing, and then places the processed sheet (bundle) on the stack tray. It is configured to accommodate. Each configuration will be described in detail.

[Configuration of Image Forming Apparatus]
The image forming apparatus A includes a paper feeding unit 2, an image forming unit 3, and an image data storage unit in a casing 1. The sheet feeding unit 2 is composed of, for example, a plurality of sheet feeding cassettes 11a, 11b, and 11c. Each cassette 11a to 11c stores a standard size sheet selected in advance. The paper feed unit 2 is provided with a manual feed tray (not shown) so that a user can insert a sheet according to the purpose of use. The sheet set in the sheet feeding unit 2 having such a configuration is a control panel 63 whose sheet conditions such as size, paper quality (coating paper or plain paper), paper thickness (thick paper or thin paper) and the like are described later. It is configured to input information from.

  The image forming unit 3 is configured to form an image on a sheet sent from the paper feeding unit 2, and the illustrated one shows an electrostatic image forming mechanism. The image forming unit 3 includes a photosensitive drum 13, a print head (laser light, LED light, etc.) 14 for forming a latent image on the drum surface, and an image forming unit Y (yellow). ), M (magenta), C (cyan), and K (black), four image forming units 3Y, 3M, 3C, and 3K are provided. The image ink (toner) formed on the photosensitive drums of the units 3Y to 3K is transferred to the transfer belt 16 by the transfer charger 17.

  Therefore, an electrostatic latent image is formed on the photosensitive drum 13 by the print bed 14, toner is adhered by the developing device 15, and this image is transferred onto the transfer belt 16 by the transfer charger 17. In the case of a color image, the final image is formed on the transfer belt 16 by superimposing YMCK color data on this image transfer. Then, this image is transferred onto the sheet sent from the paper feed unit 2 to the paper feed path P1. A charger 18 for transferring an image onto a sheet is shown in FIG.

  The sheet on which the image has been transferred in this manner is carried out to the paper discharge path P2 through the fixing device 19. In addition, the image forming unit 3 is not limited to the illustrated electrostatic image forming mechanism, and various image forming mechanisms such as an ink jet image forming mechanism and an offset image forming mechanism can be employed.

  Although not shown, the image data storage unit is configured by a storage memory for image data formed on the photosensitive drum 13 by the print head 14 of the image forming unit 3 so that data is transferred from the image reading unit 5 to the storage unit. It has become. Data is transferred to the image data storage unit also from, for example, a networked computer.

  In the image forming apparatus A configured as described above, an image reading unit 5 for reading a document image is mounted on the upper portion thereof, and a document feeding unit 6 is further mounted on the upper portion thereof. Although not shown, the image reading unit 5 includes a platen on which an original sheet is set, a reading carriage that scans the original image along the platen, and a photoelectric conversion unit that forms an image of reflected light from the original image and performs photoelectric conversion. 7 is provided. The document feeding unit 6 includes a feeder mechanism (not shown) that separates the document sheets set on the sheet feeding tray 9 one by one and automatically feeds them to the platen of the image reading unit 5.

[Sheet post-processing equipment]
The sheet post-processing apparatus B is built in the above-described image forming apparatus A as follows. The above-described image forming apparatus A carries out the sheet on which the image is formed on the sheet to the paper discharge path P2. The paper discharge path P2 is configured such that a paper discharge area 21 is disposed in the upper part of the casing 1, and a sheet on which an image is formed by the image forming unit 3 is carried out to the paper discharge area. The illustrated paper discharge area 21 is disposed between the upper portion of the image forming apparatus A and the image reading unit 5 disposed thereon (see FIG. 1).

  A sheet discharge unit is incorporated in the sheet discharge area 21, and the sheet post-processing apparatus B is configured to be incorporated in the casing 1 as one of the units. In the paper discharge path P2, a conveyance roller 22 is provided so as to carry out the sheet to the paper discharge area 21, and the sheet is fed out to a connection port 23 connected to the paper discharge unit.

  Next, a sheet post-processing apparatus (hereinafter referred to as “paper discharge unit”) B will be described with reference to FIG. The paper discharge unit B includes a paper discharge path (paper discharge path of the paper discharge unit; the same applies hereinafter) P3 connected to the connection port 23 of the paper discharge path P2, and a paper discharge port 24 provided at the exit end of this path. . A paper discharge roller 25 is provided at the paper discharge port 24 by a pair of rollers (25a, 25b), and a driving motor (not shown) is connected to the roller 25b shown in the figure. Further, an ejection path P4 is branched from the paper ejection path P3 of the paper ejection unit via a path switching flapper 26, and an overflow stacker (not shown) is disposed downstream of the ejection path P4. Yes.

  An overflow sheet, an interrupt job sheet, and the like are carried out to the overflow stacker. In the paper discharge path P3, a carry-in sensor S1 is arranged at the illustrated position, detects the leading edge of the sheet, and controls the subsequent path switching flapper 26, paper discharge roller 25, and the like. The paper discharge sensor S2 is disposed in the paper discharge port 24 or the paper discharge path P3 on the upstream side thereof, detects the front and rear ends of the sheet, and controls the subsequent paper discharge rotator 35, aligning belt 40, and the like.

  On the other hand, a step Hd (see FIG. 3A) is formed on the downstream side of the paper discharge port 24, and the processing tray 28 is disposed on the downstream side thereof. The processing tray 28 and the stack tray 29 are sized so that the stack tray 29 supports the leading edge of the sheet from the sheet discharge outlet 24 and the processing tray 28 bridges the trailing edge. That is, the processing tray 28 is configured to have a dimension shorter than the length of the smallest size sheet in the sheet discharge direction, and supports the rear end portion of the sheet whose front end portion is supported by the stack tray 29. Hereinafter, the processing tray 28 and the stack tray 29 will be described in this order.

[Processing tray configuration]
As shown in detail in FIG. 3 (a), the processing tray 28 is constituted by a tray member having a paper loading surface 28a, and a trailing edge regulating stopper (sheet edge regulating means; The same applies hereinafter) 30 is arranged. The paper loading surface 28a may have a shape that supports the sheet in a horizontal posture, or a shape that supports the sheet in an inclined posture so that the rear end side of the sheet (the rear end side in the paper discharge direction; the same applies hereinafter) is lowered. Also good.

  The rear end restricting stopper 30 is disposed at a distance Ld from the sheet discharge port 24, and a sheet end restricting surface 30a for restricting the rear end edge of the sheet to be abutted and a sheet pushing up restricting surface for restricting overcoming by curling of the sheet front end. It is comprised with the stopper member which has 30b. 30c shown in the figure is a front end pressing piece that restricts the front end of the sheet, and a base end portion is fixed to a stopper member so as to press and correct the curled front end of the sheet made of an elastically deformable plate material (FIG. 3B). )reference).

  The processing tray 28 is provided with a sheet transfer unit 31 that transfers a sheet from the sheet discharge outlet 24 toward the trailing edge regulating stopper 30 and a side alignment unit 32 that aligns the side edges of the sheet. The sheet transfer means 31 is configured to be movable up and down with respect to the paper placement surface 28a. The structure is shown in FIG. 2B. The sheet transfer means 31 includes a bracket (elevating support means; the same applies hereinafter) 34 that swings up and down, and a sheet discharge rotating body (forward / reverse roller; The same) 35 and a lifting motor MS.

  The bracket 34 has a base end supported by an apparatus frame (not shown) supported by a swinging rotation shaft 33 and a forward / reverse rotation roller 35 supported by a bearing at the distal end. The forward / reverse roller 35 is connected to a forward / reverse motor MR (shown in FIG. 6) to transfer the sheet in the left-right direction in FIG. Accordingly, when the forward / reverse roller 35 is rotated counterclockwise in FIG. 2B, the sheet is transferred to the trailing edge regulating stopper 30 side, and when rotated in the clockwise direction, the sheet is transferred to the stack tray 29 side.

[Raising / lowering mechanism of paper discharge rotating body]
The raising / lowering mechanism of the paper discharge rotating body (forward / reverse rotation roller) 35 will be described with reference to FIGS. As shown in FIG. 2B, the swing rotation shaft 33 is supported by a device frame (not shown), and the rotation of the forward / reverse rotation motor MR is transmitted to the swing rotation shaft 33 as a gear (see FIG. 6). ). At the same time, a follower-side collar 34j integrally formed on the base end portion of the bracket 34 is loosely supported on the swing rotation shaft 33. Therefore, the bracket 34 swings about the swinging rotation shaft 33 regardless of whether the swinging rotation shaft 33 is forward or backward.

  On the other hand, a drive side collar 34d is loosely supported by the swinging rotary shaft 33 adjacent to the driven side collar 34j, and a drive shaft MSd of the elevating motor MS is geared to the drive side collar 34d with a pinion 34p. ing. Therefore, the drive side collar 34d is rotated forward and backward by the drive shaft MSd of the elevating motor MS regardless of the rotation of the swing rotation shaft 33. A clutch spring CS is wound around the driving side collar 34d and the driven side collar 34j. The clutch spring CS is configured to be tightened by rotation of the driving side collar 34d in the direction indicated by an arrow a in FIG. 6 and relaxed by rotation in the opposite direction.

  As a result, when the drive side collar 34d is rotated in the direction of arrow a by the elevating motor MS, the clutch spring CS is contracted and the driven side collar 34j is rotated in the same direction. At this time, the bracket 34 integrated with the driven side collar 34j moves upward from the operating position Fp to the retracted position Wp. When the bracket 34 rises to the preset retracted position Wp, it hits an upper limit stopper 34u (shown in FIG. 2), and thereafter, the rotation of the sliding drive side collar 34d between the clutch spring CS and the driven side collar 34j is driven side. The frictional force is set so as not to be transmitted to the collar 34j.

  The frictional force is set such that when the clutch spring CS is contracted, the bracket 34 is held at the retracted position Wp by the frictional force between the spring and the driven collar 34j, and the bracket 34 is not lowered by its own weight. It is configured as follows. 34S shown in the figure is a position sensor that detects whether or not the bracket 34 is located at the retracted position Wp, and is configured integrally with the upper limit stopper 34u, both of which are attached to the apparatus frame.

  Next, when the drive side collar 34d is rotated in the direction opposite to the direction indicated by the arrow a by the elevating motor MS, the clutch spring CS is held in a contracted state, so that the bracket 34 descends from the retracted position Wp following the rotation. . The speed at this time is controlled by the rotational speed of the drive shaft MSd of the elevating motor MS.

  When the sheet discharge rotator (forward / reverse rotation roller) 35 supported at the front end of the bracket 34 comes into contact with the uppermost sheet on the processing tray 28, the rotation of the driving collar 34d (the loose side in the direction opposite to the arrow a direction). ), The clutch spring CS is relaxed, and the bracket 34 is stopped at the operating position Fp of the sheet discharge rotating body 35 by the sliding rotation between the spring and the driving side collar 34d. While the paper discharge rotator 35 is thus moved from the retracted position Wp to the operating position Fp, the control CPU 65 described later activates the forward / reverse rotation motor MR to move the paper discharge rotator 35 in the counterclockwise direction of FIG. And the sheet is transferred to the trailing edge regulating stopper 30 side.

  Accordingly, the bracket 34 swings clockwise and counterclockwise about the swinging rotation shaft 33 by forward and reverse rotation of the lifting motor MS. That is, when the pinion 34p is rotated in the clockwise direction in the figure, the forward / reverse roller 35 is moved to the retracted position Wp separated from the paper loading surface 28a in the same figure, and when the pinion 34p is rotated in the counterclockwise direction, the forward / reverse roller 35 is moved to the solid line in the figure. The operation position Fp is in contact with the paper sheet surface 28a in the state. A forward / reverse rotation force is transmitted to the forward / reverse roller 35 from a forward / reverse motor MR connected to the swing rotation shaft 33.

  A follower roller 36 is provided on the paper loading surface 28 a of the processing tray 28 so as to face the forward / reverse roller 35. The forward / reverse rotation roller 35 rotates counterclockwise in FIG. 2A when the sheet is transferred from the sheet discharge outlet 24 toward the trailing edge regulating stopper 30 by the forward / reverse rotation motor MR, and is post-processed from the trailing edge regulating stopper 30. When the sheet (bundle) is transferred to the stack tray 29 on the downstream side, the sheet rotates in the clockwise direction in FIG.

"Aligning means"
An aligning means 40 is disposed between the sheet transfer means 31 and the trailing edge regulating stopper 30. The aligning means 40 shown in the drawing, in cooperation with the sheet transfer means 31, transfers the sheet rear end carried out from the sheet discharge outlet 24 toward the rear end restriction stopper 30. Therefore, the aligning means 40 includes a ring-shaped belt 40v and a swing lever 43 that moves the belt 40v up and down according to the sheet stacking amount of the processing tray 28 as shown in FIG. Yes.

  One end of the swing lever 43 is pivotally supported by the rotation shaft 42 of the paper discharge roller (drive side roller) 25b described above, and one end of the belt 40v is wound around the paper discharge roller 25b. The belt tip is configured to hang down so as to engage with the sheet on the processing tray 28. Accordingly, the belt 40v rotates in the counterclockwise direction in FIG. 3B by the driving rotation of the paper discharge roller 25b, and the swing lever 43 swings by its own weight around the rotation shaft 42.

  A tip guide 41 is fixed to the swing lever 43 together with the belt 40v. The leading edge guide 41 is formed of a film member (mylar) that guides the trailing edge of the sheet fed by the belt 40v toward the trailing edge regulating stopper 30. The rotation center 42o of the rotation shaft 42, the sheet engagement portion 40p of the belt 40v, and the sheet engagement portion 41p of the leading end guide 41 are arranged in the order of the rotation center 42o, the engagement portion 40p, and the engagement portion 41p in the sheet transfer direction. They are arranged at a distance (see FIG. 3B).

"Side alignment means"
The processing tray 28 is provided with side alignment means 32 for regulating the position of the side edge of the sheet whose rear end is positioned on the rear end regulating stopper 30 described above. The side aligning means 32 includes a center reference for aligning with respect to the center (center) of the sheet carried into the processing tray 28 from the sheet discharge outlet 24, and a side reference for aligning with respect to the left and right side edges of the sheet. The side edge of the sheet is configured to be aligned to one of the reference positions.

  As shown in FIG. 5, the side aligning means 32 includes a left aligning plate 32L that engages with the left edge of the sheet carried into the processing tray 28, a right aligning plate 32R that engages with the right edge of the sheet, and aligning these. Alignment motors Mz1 and Mz2 move the plate in the direction perpendicular to the paper discharge. The left and right alignment plates 32L and 32R are fitted and supported in slit grooves 28z formed on the paper loading surface 28a of the processing tray, respectively, and can be moved in the sheet width direction. A pair of pulleys 32p is disposed at the bottom of the tray along the slit groove 28z, and a belt 32v is stretched over the pulleys 32p. The left and right alignment plates 32L and 32R are fixed to the belt 32v, and the alignment motors Mz1 and Mz2 are coupled to one of the pulleys 32p.

  When the alignment motors Mz1 and Mz2 are rotated in the opposite direction by the same amount, the left and right alignment plates 32L and 32R approach and separate from the sheet center. The left and right alignment plates 32L and 32R are provided with position sensors at preset home positions, and the alignment plates 32L and 32R are positioned at the home positions when the apparatus is activated. Therefore, a control means (control CPU) 65, which will be described later, receives sheet size information from the image forming apparatus A, and based on this information, the control means moves the left and right alignment plates 34L, 34R to a predetermined retracted position (FIG. 5B). Move to Wp) and wait. The retreat position Wp is set to a position (a position for forming the alignment operation width) that is a predetermined amount away from the width size of the sheet that is carried into the processing tray 28.

  Accordingly, the control means (control CPU) 65 determines the left and right alignment motors Mz1 after the expected time (after a predetermined time has elapsed from the paper discharge sensor S2) that the rear end of the sheet carried from the paper discharge port 24 reaches the rear end regulating stopper 30. , Mz2 are rotated synchronously by a predetermined amount in the opposite direction, and the left and right alignment plates 34L, 34R are moved to the alignment position (FIG. 5 (b) Ap). As a result, the sheets carried onto the processing tray are aligned and aligned.

"Post-processing means"
The post-processing means 37 arranged on the processing tray 28 will be described. As shown in FIG. 3A, the post-processing means 37 is built in the casing 8 of the paper discharge unit B so as to perform post-processing on the sheet (bundle) that is abutted against the rear-end regulating stopper 30. . The illustrated post-processing means 37 is composed of staple means. Since the stapling means (apparatus) is well known, its description is omitted. However, the stapling needle (blank) connected in a strip shape accommodated in the cartridge is folded into a U-shape and inserted into the sheet bundle with a driver member. Enter. The needle tip is composed of a unit that bends with an anvil member arranged to face the driver member.

  A drive cam and a staple motor are mounted on the unit frame 10, and a driver member is lowered by an instruction signal from a post-processing control unit (control CPU) 65 described later to execute a staple operation. The unit frame 10 is slidably fitted and supported on the guide rails 38a and 38b, and is configured to be movable in the width direction of the sheets (bundles) on the processing tray 28. Further, a screw shaft 39 is fixedly disposed on the unit frame 10, and a stapling means (post-processing means) 37 is moved in the sheet width direction by a drive motor (not shown).

[Stack Tray Configuration]
The configuration of the stack tray 29 will be described. The stack tray is disposed on the downstream side of the processing tray 28, and is composed of a tray member that moves up and down in accordance with the stacking amount of sheets. As shown in FIG. 2, a stack tray (tray member; the same applies hereinafter) 29 having a placement surface 29a for placing sheets is supported by a tray frame 44 fixed to the apparatus frame so as to be movable up and down. . That is, a pair of link levers 46 a and 46 b connected to each other by the support shaft 45 are provided, and each lever base end is pivotally supported by the tray frame 44 so as to be swingable.

  The stack tray 29 is supported by the slit-pin connection at the front ends of the link levers 46a and 46b. Fitting slits 29b and 29c are provided on the stack tray side, and the leading ends of link levers 46a and 46b are connected to the slits by pins 46c and 46d. A lift motor ML is gear-connected to the support shaft of one link lever 46a via a worm gear. Accordingly, the link lever 46a swings left and right in FIG. 2 by forward and reverse rotation of the lift motor ML, and the link lever 46b swings in the opposite direction by the same amount, and the stack tray 29 moves up and down in a parallel posture. It becomes. The stack tray 29 is provided with a paper surface detecting means 47 for detecting the paper surface position.

[Structure of paper surface detection means]
The structure of the paper surface detection means 47 is shown in FIG. 4, and is positioned at the sheet carry-in port (right end) of the stack tray (tray member) 29, and detects the position of the uppermost surface of the sheets stacked on the placement surface 29a. . Therefore, a paper surface detection lever 47a that comes into contact with the uppermost sheet, an operation solenoid 48 that retracts the paper surface detection lever 47a from the placement surface 29a when the sheet is carried in, and contacts the sheet surface after the sheet is carried in, and a detection position of the paper surface detection lever 47a. It comprises sensors 49a and 49b for detecting. The paper surface detection lever 47a is supported by the apparatus frame so as to be swingable by a support shaft 47b, and is always urged by a spring 50 toward the retracted position. The paper surface detection lever 47a is integrally provided with a flag 47c, and the rotational displacement of the flag 47c is detected ON / OFF by the first sensor 49a and the second sensor 49b.

  The paper surface detection lever 47a is shifted from the retracted position to the detection position (solid line state in FIG. 4) against the spring 50 by the operating solenoid 48, and at this time, the position of the uppermost paper surface on the stack tray is detected. Yes. The first and second sensors 49a and 49b and the flag 47c are set to the home position when the first sensor 49a shown in FIG. 4 is “OFF” and the second sensor 49b is “ON”. is there. Therefore, when both the first and second sensors 49a and 49b are “ON”, the detection paper surface is too high, and the stack tray 29 is lowered by a predetermined amount. When both the first and second sensors 49a and 49b are "OFF", the detection paper surface is too low and the tray is raised by a predetermined amount. Reference numeral 51 denotes a lower limit sensor that detects the lower limit position of the stack tray 29.

  The loading surface 29a of the stack tray 29 is moved up and down by the detection signal of the paper surface detecting means 47. The vertical movement of the tray controls the lift motor ML described above. For example, when the lift motor ML is configured by a DC motor, the rotation amount is controlled by the power supply time to the motor, or an encoder is provided on the motor rotation shaft and the rotation amount is controlled by an encoder pulse. When the lift motor ML is constituted by a pulse motor, the amount of rotation is controlled by a power pulse.

[Description of control configuration]
The control configuration of the above-described image forming system will be described with reference to the block diagram of FIG. The image forming system shown in FIG. 1 includes a control unit (hereinafter referred to as “main body control unit”) 60 of the image forming apparatus A and a control unit (hereinafter referred to as “post-processing control unit”) 65 of the sheet post-processing apparatus B. The main body control unit 60 includes a print control unit 61, a paper feed control unit 62, and an input unit (control panel) 63.

  Then, an “image forming mode” and a “post-processing mode” are set from the input unit (control panel) 63. The image forming mode sets mode settings such as color / monochrome printing, duplex / single-sided printing, and image forming conditions such as sheet size, sheet paper quality, number of printouts, and enlarged / reduced printing. The “post-processing mode” is set to, for example, “print-out mode”, “steple finishing mode”, “binding binding finishing mode”, or the like.

  The main body control unit 60 also sends a post-processing finishing mode and the number of sheets, information on the number of copies and binding mode (single-position binding or two or more bindings) information, and the sheet thickness of the sheet on which an image is formed. Data transfer such as information. At the same time, the main body control unit 60 transfers a job end signal to the post-processing control unit 65 every time image formation is completed.

  The above-described post-processing mode will be described. In the “print-out mode”, the sheet from the paper discharge port 24 is stored in the stack tray 29 without performing post-processing. In this case, the sheets are conveyed directly from the sheet discharge outlet 24 to the stack tray 29 without being aligned and stacked on the processing tray 28. In the “steple finishing mode”, the sheets from the sheet discharge outlet 24 are stacked on the processing tray 28 and aligned, and the sheet bundle is finished by the post-processing means 37 and then stored in the stack tray 29. In this case, the sheet to be imaged is in principle designated by the operator to a sheet of the same paper thickness and the same size.

  In the “binding binding finishing mode”, the sheets formed with the image forming apparatus A are aligned and accumulated on the processing tray 28, and finally the cover sheet is formed with the image forming apparatus A and superimposed on the sheets on the processing tray. After aligning and stapling, the stack tray 29 is accommodated. In this case, the cover sheet is designated by the operator as a cardboard sheet prepared in the paper feed cassette.

[Post-processing control unit]
The post-processing control unit 65 includes a control CPU 65 (control means; the same applies hereinafter) that operates the sheet post-processing apparatus B in accordance with the designated post-processing mode. The control unit includes a ROM 67 that stores an operation program and a RAM 66 that stores control data.

[Elevation control of paper discharge rotating body]
The present invention is configured such that when the paper discharge rotating body (forward / reverse rotation roller) 35 is moved down from the retracted position Wp to the operating position Fp, the start timing of the lowering operation can be adjusted in length according to the “image forming condition”. It is characterized by doing. Therefore, the control means (control CPU; hereinafter the same) 65 controls the above-described lifting motor MS and forward / reverse rotation motor MR as follows based on the operation program stored in the ROM 67 and the control data stored in the RAM 66.

  The operation program determines whether or not the bracket 34 is positioned at the retracted position Wp based on a signal from the position sensor 34S at the time of initialization (initialization) when the apparatus is activated. When the sensor signal is OFF, the lifting / lowering motor MS is activated in the upward direction to perform the operation of positioning the bracket 34 at the retracted position Wp. At the same time, this operation program is configured to rotationally drive the paper discharge roller 25 when the leading edge of the sheet is detected by the carry-in sensor S1. At the same time, a timer T is started by a signal when the sheet discharge sensor S2 detects the trailing edge of the sheet, and a lifting motor MS is started in the downward ascending direction by the time-up signal of the timer T to swing the bracket 34 and eject it. The paper rotating body (forward / reverse rotation roller) 35 is lowered from the retracted position Wp to the operating position Fp. The forward / reverse rotation motor MR rotates counterclockwise in FIG. 2 before the sheet discharge rotator (forward / reverse rotation roller) 35 reaches the operating position Fp.

  The control data stored in the RAM 66 includes a timer table Tt, and the timer time of the timer T is set in the timer table Tt. The timer times set in the timer table Tt are “timer time Tt1 for single-sided printing”, “timer time Tt2 for double-sided printing”, “timer time Tt3 for monochrome printing”, “color printing time” "Timer time Tt4" and "Timer time Tt5 for thick paper sheet" and "Timer time Tt6 for thin paper sheet" are stored.

  In both cases, the control data stores the basis weight (mass) when the sheet is thick paper or thin paper. This timer time is set to Tt1 <Tt2, Tt3 <Tt4, and Tt5 <Tt6. As will be described later with reference to FIG. 7, after the sheet trailing edge Se passes the paper discharge sensor S2, the landing point landing on the processing tray 28 from the paper discharge outlet 24 is one-sided printing, monochrome printing, and cardboard sheet In some cases, as shown in FIG. On the other hand, the short distance position Lx is used for duplex printing, color printing, and thin paper sheets. Therefore, the timer times Tt1 to Tt6 are set so that the seat landing point matches the set distance Lx. Therefore, when the sheet is stopped at this timer time, all the sheets are stopped at the set distance Lx.

  The timer time Tt is set as follows according to the specification of the device finger. First, the timer is configured to be different depending on whether the printing mode is single-sided printing or double-sided printing. In this case, the timer time is set constant even if there is a difference between monochrome / color printing and a difference between thick paper / thin paper. Second, the timer time is configured to be different depending on whether the printing mode is monochrome printing or color printing. In this case, the timer time is set constant even if there is a difference between single-sided / double-sided printing and a difference between thick paper and thin paper. Thirdly, the timer time is made different depending on whether the print sheet is thick paper or thin paper. In this case, the timer time is fixed even if there is a difference between single-sided / double-sided printing and monochrome / color printing.

  Fourth, the timer time Tt is set by combining the above conditions. For example, when monochrome single-sided printing is performed on thin paper, the timer time Tt is set as an average time [Tt = (Tt6 + Tt3 + Tt1) / 3] of “Tt3”, “Tt2”, and “Tt1”. Similarly, for color double-sided printing with thick paper, [Tt = (Tt5 + Tt4 + Tt2) / 3] is set. In addition, it is preferable to determine the landing point of the sheet on the processing tray under the above conditions in the above-described timer table by experiment, and prepare the optimum value in the RAM 66.

[Operation procedure of paper discharge rotating body]
The operation of the control means 65 configured as described above will be described with reference to the flowchart shown in FIG. When the apparatus power is turned on (St01), the paper discharge unit B performs an initial operation together with the image forming apparatus A (St02). In this initial operation, the control means 65 positions the paper discharge rotating body (forward / reverse rotation roller) 35 at the retracted position Wp.

  Next, the control means 65 detects that the leading edge of the sheet on which the image is formed by the image forming apparatus A reaches the carry-in sensor S1 (St03). Based on the sheet leading edge detection signal from the carry-in sensor S1, the control means 65 rotates the paper discharge roller 25 in the paper discharge direction (St04). At the same time, when the post-processing mode is set to the aforementioned printout mode, staple finishing mode or bookbinding binding finishing mode, the path switching flapper 26 is shifted to the state shown in FIG. As a result, the sheet is guided to the paper discharge port 24. When the interrupt mode is set, the route switching flapper 26 guides the sheet to the ejection route P4.

  When the sheet reaches the sheet discharge roller 25, the sheet is gradually carried out from the front end onto the processing tray 28 by the rotation. At this time, the control means 65 starts the timer T with a detection signal detected by the paper discharge sensor S2 at the trailing edge of the sheet. This timer T counts the CPU internal clock or counts the clock provided outside (St06). Before starting the timer, the control unit 65 calls the timer time from the RAM 66 and sets the timer time Tt according to the above-described image forming conditions transferred from the image forming apparatus A (St05).

  Next, the control means 65 determines whether or not the sheet discharge sensor S2 is OFF and the trailing edge of the sheet has passed the sensor (St06). Then, the timer is started by the sensor signal that the rear end of the sheet has passed the sensor position and time is measured (St07). Then, when the set timer time Tt has passed (St08), the control means 65 rotationally drives the aforementioned lifting motor MS in the downward direction. Then, the sheet discharge rotator 35 supported by the bracket 34 starts to descend from the retracted position Wp to the operating position Fp. Immediately after the timer time Tt has elapsed (or at the same time), the control means 65 drives the forward / reverse rotation motor MR to rotate (St10). This rotation direction is set in a direction opposite to the paper discharge direction for transferring the sheet to the trailing edge regulating stopper 30 side.

  With such control, as shown in FIG. 7, the sheet that has passed through the sheet discharge outlet 24 has its trailing end reached the landing point Lx shown in FIG. At this time, the sheet discharge rotator 35 is shifted from the retracted position Wp to the operating position Fp that engages with the sheet. Then, the sheet is transferred toward the trailing edge regulating stopper 30 by the rotation of the sheet discharge rotating body 35 (St12). At this time, the aligning means 40 also sends the sheet in the same direction and assists its movement. Therefore, the rear end of the sheet is abutted and aligned with the rear end regulating stopper 30 as shown in FIG.

  In the present invention, the operation timing for moving the paper discharge rotator 35 from the standby position to the operation position for engaging the sheet on the tray is the same as that in the illustrated embodiment. The case where the operation start timing to start moving toward the operation position is advanced or delayed according to the basis weight of the sheet is shown. In addition to this, the speed at which the paper discharge rotator 35 is moved from the standby position to the operating position may be set in two steps, high and low. In this case, when the basis weight of the sheet is larger than a predetermined value, the speed is set high, and when the sheet is small, the speed is set low. Further, in the present invention, the drive mechanism that descends from the retracted position Wp to the operating position Fp at the same speed as the drive rotational speed of the oscillating rotary shaft 33 connected to the above-described lifting motor MS is shown. The rotating body 35 may be configured to drop and move by its own weight from the retracted position Wp to the operating position Fp. In this case, the lifting motor MS and the bracket 34 are separated by the clutch means.

  Similarly, in the present invention, the case where the sheet from the sheet discharge port is bridge-supported by the stack tray 29 at the front end side and the processing tray 28 at the rear end side is shown. Needless to say, the entire sheet from the sheet discharge outlet may be supported on the processing tray 28.

A Image forming apparatus B Sheet post-processing apparatus (paper discharge unit)
MS Lifting motor (lifting drive means)
MR Forward / reverse motor CS Clutch spring S1 Loading sensor S2 Paper discharge sensor 25 Paper discharge roller 28 Processing tray 28a Paper placement surface 29 Stack tray (tray member)
29a Placement surface 30 Rear end regulating stopper (sheet end regulating means)
31 Sheet transfer means 32 Side alignment means 32L Left alignment plate 32R Right alignment plate 33 Oscillating rotation shaft 34 Bracket (lifting support means)
34d Drive side collar 34j Driven side collar 34p Pinion 34u Upper limit stopper 34S Position sensor 35 Forward / reverse roller (paper discharge rotator)
37 Post-processing means 40 Aligning means 47 Paper surface detection means 60 Main body control section 65 Post-processing control section Wp Retraction position Fp Operation position

Claims (7)

An apparatus for performing post-processing by collecting and collecting sheets sent from an image forming apparatus,
The paper exit,
Tray means for stacking and collecting sheets sent from the paper discharge port;
Sheet edge regulating means for regulating the edge of the sheet provided on the tray means;
A sheet discharge rotator for transferring the sheet carried on the tray means toward the sheet end regulating means;
Elevating support means for supporting the discharge rotating body so as to be movable up and down between an operating position in contact with the sheet on the tray means and a retracted position separated from the sheet;
Elevating drive means for driving the elevating support means;
Elevating control means for controlling the elevating drive means;
With
The sheet post-processing apparatus, wherein the elevating control unit is configured to be able to adjust an operation timing for moving the sheet discharge rotator from a retracted position to an operating position according to a sheet image forming condition. The raising / lowering control means is configured to advance the operation timing of moving the sheet discharge rotator from the retracted position to the operation position when the sheet basis weight is large and to delay when the sheet basis weight is small. The sheet post-processing apparatus according to claim 1. The raising / lowering control means is configured to delay the operation timing of moving the sheet discharge rotator from the retracted position to the operating position when the image is formed on one side of the sheet and delay when the image is formed on both sides of the sheet. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is provided. The tray means is configured to bridge-support a sheet from the paper discharge port with the stack tray disposed on the downstream side,
The sheet discharge rotator is disposed so as to be movable up and down above the tray unit so that the sheet from the sheet discharge port is transferred toward the sheet end regulating unit, and then the sheet is carried out to the stack tray. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is provided. The tray means is provided with post-processing means for binding the sheet ends positioned by the sheet end regulating means,
The sheet discharge rotator is constituted by a forward / reverse roller for transferring a sheet from the sheet discharge port toward the sheet end regulating unit and carrying out a post-processed sheet bundle to the stack tray disposed on the downstream side. The sheet post-processing apparatus according to any one of claims 1 to 4, wherein the sheet post-processing apparatus is provided. A sheet sensor for detecting the passage of the sheet is disposed at the discharge port or upstream thereof;
The elevating control means sets an operation timing for moving the discharge rotating body from the retracted position to the operating position based on the basis weight information of the sheet or the printing mode information on the basis of the trailing edge detection signal from the sheet sensor. 6. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is configured. An image forming apparatus for forming an image on a sheet;
A sheet post-processing device that performs post-processing by collecting and collecting sheets from the image forming apparatus;
Consisting of
An image forming system comprising a sheet post-processing apparatus having the configuration according to claim 1.

Images