JP2015218006A - Sheet supply device, image formation device, control method for sheet supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet supply device, along with an image formation device equipped with the same, and a control method of the sheet supply device, capable of continuously supplying a recording sheet at a time interval which is as short as possible while preventing occurrence of variation in a time at which the recording sheet reaches a sheet detection sensor in a case where a mechanism for transmitting a power of a drive part to a pickup roller has a play along a rotational direction.SOLUTION: In a case where a sheet supply action is an action succeeding to a sheet supply action at other sheet sending part (YES at S3), a control part sets an output timing of a control signal to a supply clutch when a recording sheet is sent behind the output timing of the control signal when a second or later record sheets are continuously sent from the same sheet sending part (S4-S8).

Description

  The present invention relates to a sheet supply apparatus, an image forming apparatus including the sheet supply apparatus, and a control method for the sheet supply apparatus.

  In general, an image forming apparatus includes a sheet feeding device including a sheet feeding unit that feeds a recording sheet from a sheet receiving unit such as a sheet cassette (paper feeding cassette) or a manual feed tray toward a conveyance path, and a control unit that controls the sheet feeding unit. Yes. The sheet feeding unit includes a pickup roller that feeds the recording sheet from the sheet receiving unit by rotating while being pressed against the recording sheet.

  Further, a sheet detection sensor for detecting the recording sheet is often provided in the conveyance path. The timing of conveying the recording sheet to the image forming unit is controlled according to the detection timing of the sheet detection sensor.

  Further, it is known that auto-change control is performed when the image forming apparatus includes a plurality of the sheet feeding units (see, for example, Patent Document 1). The auto-change control is a control for continuously sending out a plurality of the recording sheets while automatically selecting the sheet delivery unit to be subjected to the sheet feeding operation according to a predetermined selection rule.

  In addition, it is known to adjust the recording sheet conveyance interval in accordance with the actual value of the recording sheet conveyance time (see, for example, Patent Document 2).

JP-A-8-248709 JP 2013-130772 A

  By the way, in the said sheet supply apparatus, it is possible that the mechanism which transmits the motive power of a drive part to the said pick-up roller has play in the rotation direction of the said pick-up roller. In such a case, it is conceivable that the control unit starts supplying the recording sheet at a fixed timing with reference to the occurrence of a supply start event for each recording sheet.

  In the above case, due to the play, the time from when the recording sheet reaches the sheet detection sensor from the sheet receiving portion may vary. Then, when the recording sheet is continuously supplied at a short time interval, the recording sheet may reach the position of the sheet detection sensor at a time interval shorter than the time interval detectable by the sheet detection sensor. .

  Further, for example, when the variation caused by the play occurs only under a specific condition, the occurrence of the variation is prevented even when the recording sheet conveyance interval is adjusted according to the actual value of the recording sheet conveyance time. Can not.

  The object of the present invention is to prevent occurrence of variations in the time for the recording sheet to reach the sheet detection sensor when the mechanism for transmitting the power of the driving unit to the pickup roller has a play in the rotation direction, and at as short a time interval as possible. It is an object of the present invention to provide a sheet supply apparatus capable of continuously supplying recording sheets, an image forming apparatus including the same, and a method for controlling the sheet supply apparatus.

  A sheet feeding apparatus according to an aspect of the present invention includes a plurality of sheet receiving units, a plurality of sheet feeding units provided for each of the sheet receiving units, and a control unit. Each of the sheet receiving portions can be loaded with a plurality of recording sheets. Each of the sheet feeding sections includes a pickup roller, a pickup engaging rotator, a coupling mechanism, and a supply clutch. The pickup roller is pressed against the recording sheet and rotates to feed the recording sheet from the sheet receiving unit. The pickup engaging rotator is rotatably supported and engages with the pickup roller. The coupling mechanism engages with the pickup engaging rotator with play in the rotation direction. The supply clutch is selectively switched between a state in which power is transmitted from the drive unit to the coupling mechanism and a state in which the transmission is released in accordance with an input control signal. The control section outputs the control signal to each of the supply clutches at a timing based on the occurrence of a supply start event for each of the recording sheets. A sheet feeding operation to be sent out from the sheet receiving unit is executed. The control unit, when causing the sheet feeding unit to execute the sheet feeding operation, from the sheet feeding unit, when the sheet feeding operation is an operation continuous with the sheet feeding operation of another sheet feeding unit. The output timing of the control signal when the first recording sheet is sent out is based on the output timing of the control signal when the second and subsequent recording sheets are sent from the same sheet sending unit. The delay control is also executed.

  An image forming apparatus according to another aspect of the present invention is an image forming apparatus that forms an image on the recording sheet supplied from the sheet feeding device according to one aspect of the present invention and the sheet feeding unit of the sheet feeding apparatus. A part.

  A control method for a sheet supply apparatus according to another aspect of the present invention is a control method for a sheet supply apparatus that includes a plurality of the sheet receiving units and a plurality of the sheet feeding units provided for each of the sheet receiving units. . This control method outputs the control signal to each of the supply clutches at a timing based on the occurrence of a supply start event for each of the recording sheets, thereby supplying the recording sheet to each of the sheet feeding sections. A control step in which the control unit executes a sheet supply operation to be sent out from the sheet receiving unit; The control process includes a determination process and a delay control process. The determination step determines whether the sheet supply operation is a continuous switching supply operation that is continuous with the sheet supply operation of another sheet supply unit when the sheet supply unit performs the sheet supply operation. It is a process to do. In the delay control step, when the result of the determination step is the continuous switching supply operation, the output timing of the control signal when the first recording sheet is sent out from the sheet sending unit is continued. A delay control step of delaying the output timing of the control signal when the second and subsequent recording sheets are sent out from the same sheet sending unit.

  According to the present invention, when the mechanism for transmitting the power of the driving unit to the pickup roller has play in the rotation direction, it is possible to prevent occurrence of variations in the time for the recording sheet to reach the sheet detection sensor at a time interval as short as possible. It is possible to provide a sheet supply apparatus capable of continuously supplying recording sheets, an image forming apparatus including the same, and a control method for the sheet supply apparatus.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of related devices for sheet supply control in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a first bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a second bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a third bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a fourth bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 7 is a fifth bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 8 is a sixth bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 9 is a seventh bottom view of the pickup unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 10 is a flowchart illustrating an example of a sheet supply control procedure executed by the control unit of the image forming apparatus according to the embodiment of the present disclosure.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

[Schematic Configuration of Image Forming Apparatus 10]
The image forming apparatus 10 according to an embodiment of the present invention is an electrophotographic image forming apparatus. As shown in FIG. 1, the image forming apparatus 10 includes a plurality of sheet supply units 2, a sheet conveying unit 3, an image forming unit 4, an optical scanning unit 5, a fixing unit 6, a sheet detection sensor 801, a control unit 8, and the like. Prepare.

  The image forming apparatus 10 is a multi-function machine including a document transport reading unit 1 that reads an image from a document 90 and an operation display unit 80. As another example of the image forming apparatus according to the present invention, a printer, a copier, a facsimile, or the like can be considered.

  The document conveyance reading unit 1 includes an image reading unit 11 and an ADF (Auto Document Feeder) 12. The image reading unit 11 includes a document table 111, a reading unit 112, an optical system 113 such as a mirror and a lens, a CCD (Charge Coupled Device) 114, and the like.

  The document table 111 is a portion on which a document provided on the upper surface of the image reading unit 11 is placed. The reading unit 112 irradiates the original 90 at the reading position on the original table 111 with light, and reflects the reflected light toward the optical system 113. The reading unit 112 is movable in the sub-scanning direction (left and right direction in the figure). The optical system 113 guides reflected light from the document 90 to the CCD 114. The CCD 114 includes a photoelectric conversion element that outputs an electrical signal corresponding to the amount of received light as image data of the original 90 to the control unit 8.

  The ADF 12 drives each of the plurality of transport rollers 122 to transport the document 90 set on the document placement unit 121 to the discharge tray 123 through the image reading position by the image reading unit 11. .

  Each of the sheet supply units 2 includes a sheet receiving unit 21 and a sheet sending unit 22. Each of the sheet feeding sections 22 is provided for each sheet receiving section 21. The portions of the plurality of sheet supply units 2 and the control unit 8 in the image forming apparatus 10 are sheet supply apparatuses according to an embodiment of the present invention.

  1 and 2 show an example in which the image forming apparatus 10 includes three sheet supply units 2. However, it is also conceivable that the image forming apparatus 10 includes two or four or more sheet supply units 2.

  Each of the sheet receiving portions 21 is configured so that a plurality of recording sheets 9 can be stacked and placed. The recording sheet 9 is a sheet-like image forming medium such as paper, coated paper, postcard, envelope, and OHP sheet.

  Each of the sheet feeding units 22 includes a pickup roller 221, a sheet supply roller 222, and a retard roller 223. The pickup roller 221 and the sheet supply roller 222 constitute a pickup unit 220 together with a movable support portion 2200 that supports them. Each of the sheet feeding sections 22 further includes a supply clutch 20, a coupling mechanism 23, and a pickup engaging rotator 24.

  The pickup roller 221 is pressed against the recording sheet 9 placed on the sheet receiving portion 21 and rotates. Accordingly, the sheet feeding unit pickup roller 221 sends the recording sheet 9 from the sheet receiving unit 21 to between the sheet supply roller 222 and the retard roller 223. The pickup roller 221 is pressed against the recording sheet 9 as the movable support portion 2200 rotates toward the sheet receiving portion 21.

  Further, the rotating sheet supply roller 222 further sends out the recording sheet 9 sent from the pickup roller 221 toward the conveyance path 30 while being sandwiched between the retard roller 223 and the recording sheet 9. The retard roller 223 prevents the recording sheet 9 from being double fed. Each of the pickup roller 221, the sheet supply roller 222, and the retard roller 223 has an outer peripheral surface formed of an elastic member such as an elastomer or rubber.

  In the example illustrated in FIG. 1, among the three sheet supply units 2, the first sheet supply unit 2 a and the second sheet supply unit 2 b are removable from the casing 100 (main body) of the image forming apparatus 10. The cassette-type sheet receiving portion 21 is provided. The remaining third sheet supply unit 2 c includes the sheet receiving unit 21 that forms a manual feed tray that can be folded with respect to the casing 100 (main body) of the image forming apparatus 10.

  In FIG. 2, the supply clutches 20 corresponding to the first sheet supply unit 2a, the second sheet supply unit 2b, and the third sheet supply unit 2c are respectively the first supply clutch 20a and the second supply clutch. 20b and third supply clutch 20c.

  Each of the supply clutches 20 is in a connected state in which power is transmitted to the coupling mechanism 23 from a driving unit such as a gear driven by a motor according to an input control signal, and in a state in which the transmission is released. The clutch is selectively switched to a released state. The details of the coupling mechanism 23 and the pickup engaging rotator 24 will be described later.

  The sheet conveyance unit 3 includes a registration roller 31, a conveyance roller 32, a discharge roller 33, and the like. The registration roller 31 and the conveyance roller 32 convey the recording sheet 9 supplied from the sheet supply unit 2 toward the image forming unit 4. Further, the discharge roller 33 discharges the recording sheet 9 after image formation from the discharge port of the transport path 30 onto the discharge tray 101.

  The sheet detection sensor 801 that detects the recording sheet 9 is provided in the conveyance path 30. More specifically, the sheet detection sensor 801 is provided at a position upstream of the registration roller 31 in the conveyance direction of the recording sheet 9. The sheet detection sensor 801 detects that the recording sheet 9 supplied from each of the sheet supply units 2 has reached a position in front of the registration roller 31 in the conveyance path 30.

  Further, the control unit 8 controls the stop and rotation of the registration roller 31 according to the timing when the sheet detection sensor 801 detects the recording sheet 9. As a result, the conveyance timing of the recording sheet 9 to the image forming unit 4 is adjusted.

  The image forming unit 4 forms an image on the surface of the recording sheet 9 that is supplied from the sheet feeding unit 22 and is moving along the conveyance path 30. The image forming unit 4 includes a drum-shaped photoconductor 41, a charging unit 42, a developing unit 43, a transfer unit 45, a cleaning unit 47, and the like. The photoreceptor 41 is an example of an image carrier.

  The photoconductor 41 rotates, and the charging unit 42 uniformly charges the surface of the photoconductor 41. Further, an electrostatic latent image is written on the surface of the photosensitive member 41 charged by the optical scanning unit 5 scanning the laser beam, and the developing unit 43 supplies toner to the photosensitive member 41, thereby The electrostatic latent image is developed into a toner image. The toner is supplied from the toner container 40 to the developing unit.

  Further, the transfer unit 45 transfers the toner image of the photoconductor 41 to the recording sheet 9 moving on the conveyance path 30. Finally, the cleaning unit 47 removes the toner remaining on the surface of the photoreceptor 41.

  The fixing unit 6 sandwiches the recording sheet 9 on which the toner image is formed between a fixing roller 61 including a heater such as a halogen heater and a pressure roller 62, and sends the recording sheet 9 to a subsequent process. Thus, the fixing unit 6 heats the toner image (image) on the recording sheet 9 and fixes the image on the recording sheet 9.

  The control unit 8 displays an operation menu or the like on the operation display unit 80. Further, the control unit 8 controls various electric devices including the supply clutch 20 based on input information input through the operation display unit 80 and detection results of various sensors including the sheet detection sensor 801. For example, as shown in FIG. 2, the control unit 8 includes an MPU (Micro Processor Unit) 81, a memory 82, and a signal interface 83.

  The MPU 81 is a processor that executes various arithmetic processes. The memory 82 is a nonvolatile storage unit in which information such as control programs Pr1, Pr2, Pr3, Pr4, and Pr5 for causing the MPU 81 to execute various processes is stored in advance. Further, the memory 82 is also a storage unit in which various information can be read and written by the MPU 81.

  The control unit 8 controls the image forming apparatus 10 in an integrated manner by the MPU 81 executing various control programs Pr1, Pr2, Pr3, Pr4, and Pr5 stored in the memory 82 in advance.

  The signal interface 83 is an interface circuit that relays signal transfer between the MPU 81 and the sensors and control target devices. The MPU 81 inputs detection signals (measurement signals) from various sensors such as the sheet detection sensor 801 via the signal interface 83. Further, the MPU 81 outputs a control signal to a control target device such as the supply clutch 20 via the signal interface 83.

[Details of Sheet Sending Unit 22]
Next, the details of the sheet feeding unit 22 will be described with reference to FIGS. 3 and 4 are bottom views of the pickup unit 220 in different states.

  The pickup unit 220 includes the coupling mechanism 23 and the pickup engagement rotating body 24 in addition to the pickup roller 221, the sheet supply roller 222, and the movable support portion 2200.

  The pickup engaging rotator 24 is a member that is supported so as to be rotatable about the rotation center line of the pickup roller 221. The pickup engagement rotating body 24 can be engaged with each of the coupling mechanism 23 and the pickup roller 221. The coupling mechanism 23 is a mechanism for transmitting the power acting from the supply clutch 20 to the sheet supply roller 222 and the pickup engaging rotator 24. 3 and 4, the supply clutch 20 is drawn with a virtual line (two-dot chain line).

  The supply clutch 20 is a clutch that selectively switches between a state in which power is transmitted from the drive unit (not shown) to the rotating shaft 2221 of the sheet supply roller 222 and a state in which the transmission is released.

  The connection mechanism 23 includes a one-way clutch 230, a first gear 231, a second gear 232, and a third gear 233. The one-way clutch 230 and the first gear 231 are provided on a rotation shaft 2221 of the sheet supply roller 222. The third gear 233 is provided on the rotation shaft 2211 of the pickup roller 221. The first gear 231 meshes with the second gear 232, and the second gear 232 meshes with the third gear 233.

  Hereinafter, a direction in which the pickup roller 221 and the sheet supply roller 222 rotate when the recording sheet 9 is sent out is referred to as a forward direction, and an opposite rotation direction is referred to as a reverse direction. In addition, a direction R1 indicated by a straight arrow in each drawing is a traveling direction of the recording sheet 9.

  When the supply clutch 20 is in the connected state, the one-way clutch 230 and the first gear 231 rotate in the forward direction. Further, in conjunction with the one-way clutch 230, the sheet supply roller 222 also rotates in the forward direction. Further, when the second gear 232 rotates in conjunction with the first gear 231, the third gear 233 also rotates in the forward direction. The third gear 233 is formed with an overhang portion 234 that extends in the direction of the rotating shaft 2211.

  An end surface on the downstream side in the forward rotation direction of the overhang portion 234 is a tapered surface 2341 that is inclined in a direction in which it gradually widens from the tip side to the root side.

  The pickup roller 221 and the pickup engaging rotator 24 are supported so as to be rotatable with respect to the rotary shaft 2211. The pickup engaging rotator 24 is formed with a recess 242 where the overhanging portion 234 is hooked (engaged), and a first sawtooth gear 241 opposite to the recess 242. The pickup roller 221 is formed with a second serrated gear 224 that meshes with (engages with) the first serrated gear 241.

  The upstream edge in the forward rotation direction of the concave portion 242 of the pickup engaging rotator 24 is referred to as an upstream edge 2421, and the downstream edge in the forward rotation direction is the downstream side. This is referred to as edge 2422.

  The width of the concave portion 242 in the circumferential direction of the pickup engaging rotator 24 is sufficiently larger than the width of the overhang portion 34. Therefore, the overhanging portion 234 of the third gear 233 engages with the recess 242 of the pickup engagement rotating body 24 with play in the rotation direction. That is, the coupling mechanism 23 engages with the pickup engaging rotator 24 with play in the rotation direction.

  The supply clutch 20 transmits power (rotational force) to the connection mechanism 23, and the connection mechanism 23 transmits power to the sheet supply roller 222 and the pickup engagement rotator 24. Transmits power to the pickup roller 221. Thereby, when the supply clutch 20 is in the connected state, the sheet supply roller 222 and the pickup roller 221 rotate in the forward direction.

  3 shows a state in which the overhang portion 234 is located closest to the upstream edge 2421 in the recess 242, and FIG. 4 shows the overhang portion 234 in the recess 242 that is the most downstream edge 2422. The state where it is located near is shown.

  The pickup engaging rotator 24 is supported between the third gear 233 and the second sawtooth gear 224 so as to be slidable in the direction along the rotation shaft 2211. FIG. 3 shows a state in which the pickup engaging rotator 24 is positioned closest to the third gear 233 and the first sawtooth gear 241 and the second sawtooth gear 224 are disengaged. On the other hand, FIG. 4 shows a state where the pickup engaging rotator 24 is located closest to the second sawtooth gear 224 and the first sawtooth gear 241 and the second sawtooth gear 224 are engaged with each other. .

[Details of Movement of Pickup Unit 220]
Next, details of the movement of the pickup unit 220 when the sheet supply unit 2 performs a sheet supply operation of sending the recording sheet 9 from the sheet receiving unit 21 will be described with reference to FIGS. The phenomenon shown below has not been clearly grasped conventionally, and is a phenomenon that has been revealed for the first time by various experiments.

  As shown in FIG. 5, when the supply clutch 20 is in the connected state (ON state), the coupling mechanism 23 transmits a rotational force in the forward direction to the sheet supply roller 222 and the third gear 233. At this time, the third gear 233 rotates in the forward direction, so that the tapered surface 2341 of the projecting portion 234 contacts the downstream edge 2422 of the concave portion 242 of the pickup engagement rotating body 24. Therefore, the downstream side edge 2422 slides on the tapered surface 2341, and the pickup engagement rotating body 24 is displaced toward the second sawtooth gear 224 side. As a result, the first sawtooth gear 241 and the second sawtooth gear 224 are engaged with each other, and the pickup roller 221 rotates in the forward direction in conjunction with the rotation of the pickup engagement rotating body 24.

  That is, when the supply clutch 20 is in the connected state (ON state), the sheet supply roller 222 and the pickup roller 221 are rotated in the forward direction by the transmission of power by the coupling mechanism 23 to rotate the recording sheet 9. The sheet is sent from the sheet receiving unit 21. This operation is the sheet supply operation. The control unit 8 outputs the control signal to each of the supply clutches 20 at a timing based on a supply start event that occurs every time the recording sheet 9 needs to be sent out. Accordingly, the control unit 8 causes each of the sheet feeding units 22 to execute a sheet supply operation.

  When the sheet supply unit 2 performs the sheet supply operation, the elastic member forming the outer peripheral surface of the retard roller 223 is an attractive force (frictional force) in the traveling direction R1 of the recording sheet 9 received from the recording sheet 9. Due to the elastic deformation.

  The one-way clutch 230 limits the rotation of the sheet supply roller 222 in the reverse direction, but does not limit the rotation of the sheet supply roller 222 in the forward direction. The first sawtooth gear 241 meshes with the second sawtooth gear 224 when the pickup engaging rotator 24 rotates in the forward direction, but does not limit the forward rotation of the pickup roller 221. . Therefore, the sheet supply roller 222 and the pickup roller 221 can always rotate in the forward direction.

  Accordingly, even when the supply clutch 20 is in the released state (OFF state) and the coupling mechanism 23 is stopped, the sheet supply roller 222 and the pickup roller 221 are moved forward when an external force is applied. Can only rotate.

  As shown in FIG. 6, when the supply clutch 20 is in the released state and the sheet supply operation is finished, the pickup roller 221 is applied by the force or inertia received from the recording sheet 9 conveyed by the sheet conveyance unit 3. The sheet supply roller 222 continues to rotate in the forward direction and then stops. Then, a force for rotating in the forward direction and a force for displacing toward the third gear 233 act on the first sawtooth gear 241 from the second sawtooth gear 224. As a result, the first sawtooth gear 241 and the second sawtooth gear 224 are disengaged, and the upstream edge 2421 of the recess 242 approaches the overhang portion 234. Hereinafter, this state is referred to as a state immediately after the connection is released.

  FIG. 7 shows the state of the pickup unit 220 when the supply clutch 20 is brought into the connected state in almost no time from the state immediately after the release of the connection. In this case, the overhang portion 234 starts to rotate in the forward direction from a position near the upstream edge 2421 in the recess 242.

  Therefore, after the supply clutch 20 is in the connected state, the pickup roller 221 starts rotating after a time for the overhanging portion 234 to rotate the play of the recess 242 has elapsed. The time for rotating the play of the concave portion 242 is the time required for the overhang portion 234 to rotate from a position near the upstream edge 2421 in the concave portion 242 to a position in contact with the downstream edge 2422. It is.

  8 and 9 show the state of the pickup unit 220 when the supply clutch 20 remains in the released state for a while from the state immediately after the release of the connection. In this case, the elastic member forming the outer peripheral surface of the retard roller 223 returns from the state of being elastically deformed in the traveling direction R1 of the recording sheet 9 to the lower state. Accordingly, as shown in FIG. 8, the sheet supply roller 222 in contact with the retard roller 223 is slightly rotated in the reverse direction, and the overhang portion 234 is also rotated in the reverse direction slightly in conjunction therewith.

  Further, the overhanging portion 234 rotated slightly in the reverse direction pushes the upstream edge 2421 of the recess 242 so as to flip in the reverse direction. Accordingly, as shown in FIG. 9, the pickup engaging rotator 24 rotates in the reverse direction until the downstream edge 2422 of the recess 242 reaches a position where it is caught by the overhanging portion 234.

  Therefore, when the sheet supply operation is resumed after a lapse of time from the state immediately after the release of the connection, the pickup roller 221 starts rotating immediately after the supply clutch 20 is in the connected state.

  As described above, in the sheet supply apparatus according to the present embodiment, the coupling mechanism 23 that transmits the power of the driving unit to the pickup roller 221 has play in the rotation direction of the pickup roller 221. Yes. In such a sheet supply apparatus, it is conceivable that the control unit 8 starts supplying the recording sheet 9 at a fixed timing with reference to the occurrence of a supply start event for each recording sheet 9.

  In the above case, due to the play, the time from when the recording sheet 9 reaches the sheet detection sensor 801 from the sheet receiving portion 21 may vary. Then, when the recording sheet 9 is continuously supplied at a short time interval, the recording sheet 9 reaches the position of the sheet detection sensor 801 at a time interval shorter than the time interval detectable by the sheet detection sensor 801. There is a risk.

  In addition, for example, when the variation in time due to the play occurs only under a specific condition, the occurrence of the variation occurs even if the recording sheet conveyance interval is adjusted according to the actual value of the recording sheet conveyance time. Cannot be prevented.

  On the other hand, in the sheet supply apparatus according to the present embodiment, the control unit 8 executes the control shown below. As a result, even when the coupling mechanism 23 that transmits the power of the driving unit to the pickup roller 221 has play in the rotation direction, the recording sheets 9 are continuously provided at a time interval as short as possible while preventing the variation in time. It becomes possible to supply.

[Control method of sheet feeding apparatus]
Next, an example of a control process of the sheet supply unit 2 executed by the control unit 8 in the image forming apparatus 10 will be described with reference to FIG. FIG. 10 is a flowchart illustrating an example of a procedure of sheet supply control processing executed by the control unit 8.

  The control step is a step in which the control unit 8 causes the sheet supply unit 20 to execute the sheet supply operation of sending the recording sheet 9 from the sheet receiving unit 21 to each of the supply clutches 20. The control unit 8 outputs the control signal at a timing based on the supply start event that occurs every time the recording sheet 9 is supplied.

  The control unit 8 starts the control process shown in FIG. 10 when, for example, a job for image formation by the image forming unit 4 occurs. In the following description, S1, S2,... Represent processing procedure identification codes. The processing of the control unit 8 shown below is realized by the MPU 81 executing a control program stored in the memory 82.

<Step S1>
First, the control unit 8 refers to the contents of the job to identify which of the plurality of sheet supply units 2 is the target of the sheet supply operation to be started. This step S1 is a step in which the MPU 81 executes the operation determination program Pr1.

<Step S2>
Further, the control unit 8 determines whether or not the sheet supply operation to be performed by the sheet supply unit 2 is a continuous switching supply operation that matches a predetermined condition. This step S2 is a step in which the MPU 81 executes the operation determination program Pr1.

  When the sheet feeding operation to be executed by the sheet feeding unit 22 identified in step S1 is an operation continuous with the sheet feeding operation of the other sheet feeding unit 22, It is determined that the continuous switching supply operation. Here, the continuous operation means that a different sheet supply operation of the sheet supply unit 22 is started within a predetermined short time from the end of the sheet supply operation of a certain sheet supply unit 22. is there.

  For example, when the job of image formation is a job accompanied with auto change control of the sheet supply unit 2, it is determined that the sheet supply operation is the continuous switching supply operation. The auto change control is a control for continuously feeding a plurality of the recording sheets 9 while automatically selecting the sheet feeding unit 22 to be subjected to the sheet feeding operation according to a predetermined selection rule. In this case, the sheet feeding operation by the sheet feeding unit 22 selected second or later in the series of auto change control is the continuous switching feeding operation.

  For example, in the auto change control, it is detected that the recording sheet 9 of the sheet receiving unit 21 corresponding to the first selected sheet feeding unit 22 has disappeared in the middle of the job (sheet remaining amount 0%). In this case, the other sheet delivery unit 22 is automatically selected and the job is continued.

  It is also conceivable that the auto change control is performed when a plurality of documents 90 having different sizes are set on the document placement unit 121 of the ADF 12. In this case, the control unit 8 detects the size of each of the documents 90 sequentially conveyed by the ADF 12 based on the image data of the document 90 obtained by the image reading unit 11. Then, the control unit 8 selects the sheet feeding unit 22 of the sheet feeding unit 2 on which the recording sheet 9 having a size corresponding to the detected size of the document 90 is set as the target of the sheet feeding operation. To do.

  Further, when a new image forming job using another sheet supply unit 2 occurs while the recording sheet 9 is continuously supplied from a certain sheet supply unit 2 for a certain image formation job. However, the sheet supply operation for the new image forming job is the continuous switching supply operation.

<Step S3>
Further, the control unit 8 is an operation for sending out the first recording sheet 9 in the series of operations of the sheet sending unit 22 as the sheet feeding operation to be executed from the sheet sending unit 22 specified in step S1. It is determined whether or not. This step S3 is also a step in which the MPU 81 executes the operation determination program Pr1.

<Step S4>
When it is determined that the sheet supply operation to be performed is the continuous switching supply operation and the first recording sheet 9 is sent out, the control unit 8 performs control described later. In the adjustment time variable Ta to be used, a value representing a time longer than a predetermined reference adjustment time by a predetermined delay time Td is set. Step S4 is a step in which the MPU 81 executes the delay control program Pr2. The reference adjustment time is predetermined for each sheet supply unit 2.

  The situation in which step S4 is executed is a situation in which the protruding portion 234 and the concave portion 242 of the pickup engaging rotator 24 are in the positional relationship shown in FIG. 9 at the start of the sheet feeding operation. That is, the overhanging portion 234 is located closer to the downstream edge 2422 in the concave portion 242.

  The delay time Td is a time required for the overhanging portion 234 to rotate (displace) by the amount of play of the concave portion 242.

<Step S5>
On the other hand, when it is determined that the sheet supply operation to be performed is not the continuous switching supply operation or the first recording sheet 9 delivery operation (after the second sheet), the control is performed. The unit 8 sets a value representing the reference adjustment time in the adjustment time variable Ta. Step S5 is a step in which the MPU 81 executes the non-delay control program Pr3.

  The situation in which step S5 is executed is a situation in which the protruding portion 234 and the concave portion 242 of the pickup engagement rotating body 24 are in the positional relationship shown in FIG. 7 at the start of the sheet feeding operation. That is, the overhang portion 234 is located closer to the upstream edge 2421 in the recess 242.

<Steps S6 to S8>
Then, the control unit 8 monitors the occurrence of the supply start event (S6). Further, when the time indicated by the adjustment time variable Ta has elapsed from the occurrence of the supply start event, the control unit 8 connects the supply clutch 20 corresponding to the sheet feeding unit 22 identified in step S1. A state is set (S7). Further, the control unit 8 returns the supply clutch to the released state after a predetermined time (S8). The control unit 8 outputs the control signal to the supply clutch 20 to place the supply clutch 20 in the connected state or the released state.

  The supply start event is, for example, that a control signal for making a clutch (not shown) of the registration roller 31 in a connected state (ON state) becomes active (ON).

  Each time the control unit 8 performs steps S6 to S8, one recording sheet 9 is sent out from the sheet receiving unit 21 toward the conveyance path 30. Steps S6 to S8 are steps in which the MPU 81 executes the clutch control signal output program Pr4.

  In addition, the process of step S1-S3 which the said control part 8 performs is an example of the said determination process. In the determination step, when the sheet feeding unit 22 performs the sheet feeding operation, the sheet feeding operation is the continuous switching feeding operation that is continuous with the sheet feeding operation of the other sheet feeding unit 22. It is the process of determining.

  Moreover, the process of step S4-S8 which the said control part 8 performs is an example of the said delay control process. In the delay control step, when the result of the determination step is the continuous switching supply operation, the output timing of the control signal when sending the first recording sheet 9 from the sheet sending unit 22 is This is a step of delaying the output timing of the control signal when the second and subsequent recording sheets 9 are continuously sent out from the same sheet sending unit 22.

<Step S9>
Next, the control unit 8 determines whether or not a predetermined standby condition is satisfied. The waiting condition is, for example, a state in which a new image forming job does not occur until a predetermined time elapses after the image forming process ends. This step S9 is a step in which the MPU 81 executes the standby determination program Pr5.

  And the said control part 8 repeats the process from step S1 shown above to step S9 at any time as long as the said standby conditions are not satisfied. For example, the control unit 8 executes the processing from step S1 to step S9 every elapse of a predetermined time. Further, when the control unit 8 determines that the standby condition is satisfied, the control unit 8 shifts to the standby state.

  As described above, according to the sheet feeding device of the image forming apparatus 10, the adjustment time variable Ta and the overhanging portion 234 of the coupling mechanism 23 that engages with play in the rotation direction. The pickup engagement rotating body 24 is changed according to the positional relationship with the concave portion 242.

  As a result, the time for the recording sheet 9 to reach the sheet detection sensor 801 is prevented from varying even though the coupling mechanism 23 that transmits the power of the driving unit to the pickup roller 221 has the play. it can. As a result, it is possible to prevent the recording sheet 9 from reaching the position of the sheet detection sensor 801 at a time interval shorter than the time interval detectable by the sheet detection sensor 801.

  Further, the control unit 8 does not perform the delay control step when the sheet supply operation is not the continuous switching supply operation. Further, the delay time Td is set only in a very limited case when the first recording sheet 9 is supplied in the continuous switching supply operation. Therefore, when a plurality of recording sheets 9 are continuously supplied, the second and subsequent recording sheets 9 can be continuously supplied at a time interval as short as possible.

[Other application examples]
The procedure of the control process shown in FIG. 10 is merely an example, and it is conceivable that the control process is performed by another procedure. For example, it is conceivable that step S2 and step S3 are performed in the reverse order.

  The sheet supply apparatus, the image forming apparatus, and the sheet supply apparatus control method according to the present invention can be freely combined within the scope of the invention described in each claim, Alternatively, the embodiment and application examples can be appropriately modified or partly omitted.

1: Document transport reading unit 2: Sheet feeding unit 3: Sheet transport unit 4: Image forming unit 5: Optical scanning unit 6: Fixing unit 8: Control unit 9: Recording sheet 10: Image forming apparatus 11: Image reading unit 12: ADF
20: Supply clutch 21: Sheet receiving unit 22: Sheet delivery unit 23: Connection mechanism 24: Pickup engagement rotating body 30: Conveying path 31: Registration roller 32: Conveying roller 33: Discharging roller 34: Overhanging unit 40: Toner container 41: Photoconductor 42: Charging unit 43: Developing unit 45: Transfer unit 47: Cleaning unit 61: Fixing roller 62: Pressure roller 80: Operation display unit 81: MPU
82: Memory 83: Signal interface 90: Document 100: Housing 101: Ejection tray 111: Document table 112: Reading unit 113: Optical system 114: CCD
121: Document placing section 122: Conveying roller 123: Paper discharge tray 220: Pickup unit 221: Pickup roller 222: Sheet supply roller 223: Retard roller 224: Second sawtooth gear 230: One-way clutch 231: First gear 232: Second gear 233: Third gear 234: Overhang portion 241: First sawtooth gear 242: Concave portion 801: Sheet detection sensor 2200: Movable support portions 2211, 2221: Rotating shaft 2341: Tapered surface 2421: Upstream edge 2422: Downstream edge Pr1: Operation determination program Pr2: Delay control program Pr3: Non-delay control program Pr4: Clutch control signal output program Pr5: Standby determination program R1: Progression direction of recording sheet

Claims (5)

A plurality of sheet receivers each capable of stacking a plurality of recording sheets,
A pickup roller that is provided for each of the sheet receiving portions and that is pressed against the recording sheet and rotates to feed the recording sheet from the sheet receiving portion, and a pickup engaging rotating body that is rotatably supported and engages with the pickup roller. A coupling mechanism that engages with the pickup engaging rotator with play in its rotational direction, a state in which power is transmitted from the drive unit to the coupling mechanism in accordance with an input control signal, and a state in which the transmission is released A plurality of sheet delivery sections each for feeding the recording sheet toward one conveyance path provided with a sensor for detecting the recording sheet from the sheet receiving section;
By outputting the control signal to each of the supply clutches at a timing based on the occurrence of a supply start event for each recording sheet, the recording sheet is sent from the sheet receiving unit to each of the sheet sending units. A control unit that executes a sheet supply operation to be performed,
The control unit, when causing the sheet feeding unit to execute the sheet feeding operation, from the sheet feeding unit, when the sheet feeding operation is an operation continuous with the sheet feeding operation of another sheet feeding unit. The output timing of the control signal when the first recording sheet is sent out is based on the output timing of the control signal when the second and subsequent recording sheets are sent from the same sheet sending unit. A sheet feeding device that performs delay control that also delays the sheet feeding.   The control unit is configured to perform auto-change control in which a plurality of the recording sheets are continuously fed while automatically selecting the sheet feeding unit to be subjected to the sheet feeding operation according to a predetermined selection rule. The sheet feeding apparatus according to claim 1, wherein delay control is executed. Each of the sheet delivery units
A sheet supply roller that further feeds the recording sheet sent from the pickup roller toward the conveyance path while sandwiching the recording sheet with a retard roller having an outer peripheral surface formed of an elastic member;
The sheet supply device according to claim 1, wherein the coupling mechanism transmits power acting from the supply clutch to the sheet supply roller and the pickup engaging rotator. The sheet feeding apparatus according to any one of claims 1 to 3,
An image forming apparatus comprising: an image forming unit that forms an image on the recording sheet supplied from the sheet sending unit of the sheet supply device. A plurality of sheet receivers each capable of stacking a plurality of recording sheets,
A pickup roller that is provided for each of the sheet receiving portions and that is pressed against the recording sheet and rotates to feed the recording sheet from the sheet receiving portion, and a pickup engaging rotating body that is rotatably supported and engages with the pickup roller. A coupling mechanism that engages with the pickup engaging rotator with play in its rotational direction, a state in which power is transmitted from the drive unit to the coupling mechanism in accordance with an input control signal, and a state in which the transmission is released Each of which has a supply clutch that selectively switches to a sheet, and a plurality of sheet delivery sections that deliver the recording sheet from the sheet receiving section toward a conveyance path provided with a sensor that detects the recording sheet. A control method for a supply device,
By outputting the control signal to each of the supply clutches at a timing based on the occurrence of a supply start event for each recording sheet, the recording sheet is sent from the sheet receiving unit to each of the sheet sending units. A control step for causing the control unit to execute the sheet supply operation to be performed,
The control step includes
A determination step of determining whether or not the sheet supply operation is a continuous switching supply operation that is continuous with the sheet supply operation of another sheet supply unit when the sheet supply unit performs the sheet supply operation;
When the result of the determination step is the continuous switching supply operation, the output timing of the control signal when the first recording sheet is sent from the sheet sending unit is continuously the same sheet sending unit. And a delay control step of delaying the output timing of the control signal when the second and subsequent recording sheets are sent out.

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