JP2015218007A - 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 for 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 displacement of the recording sheet can occur when a drawer type sheet cassette is attached to a case.SOLUTION: A control part, in a case where a first recording sheet is sent after a sheet cassette of a cassette type sheet supply part is attached (YES at S2), can set an output timing of a control signal to a supply clutch behind a time at which a second or later recording sheet is sent succeeding to it at the same cassette type sheet supply part.

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 sheet supply roller that feeds the recording sheet from the sheet receiving unit by rotating in contact with the recording sheet. The sheet cassette is detachably attached to the housing.

  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, the case where the said sheet supply roller is arrange | positioned near the edge part by the side of the drawer | drawing-out with respect to the said sheet cassette with which the said housing | casing was mounted can be considered. In this case, when the sheet cassette is mounted on the housing, the upper surface of the recording sheet comes into contact with the sheet supply roller, and the recording sheet may shift to a position downstream of the original position in the sheet feeding direction. There is.

  Therefore, when 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, the recording sheet is transferred from the sheet cassette to the sheet detection sensor. Variations occur in the time to reach. That is, when the position of the recording sheet is shifted, the recording sheet reaches the position of the sheet detection sensor earlier than when the recording sheet is not.

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

  An object of the present invention is to prevent the occurrence of variations in the time for a recording sheet to reach the sheet detection sensor as much as possible when the recording sheet can be displaced when the drawer-type sheet cassette is mounted on the housing. It is an object of the present invention to provide a sheet supply apparatus capable of continuously supplying recording sheets at short time intervals, an image forming apparatus including the sheet supply apparatus, and a control method for the sheet supply apparatus.

  A sheet supply apparatus according to an aspect of the present invention includes a plurality of sheet supply units each including a sheet receiving unit, a sheet supply roller, and a supply clutch, and a control unit. The sheet receiving unit can stack a plurality of recording sheets. The sheet supply roller is a roller that sends out the recording sheet from the sheet receiving unit toward one conveyance path provided with a sensor that detects the recording sheet by rotating in contact with the recording sheet. The supply clutch is a clutch that selectively switches between a state in which power is transmitted from the drive unit to the sheet supply roller and a state in which the transmission is released in accordance with an input control signal. The control unit outputs the control signal to each of the sheet supply units by outputting the control signal at a timing based on the occurrence of a supply start event for each recording sheet for each of the supply clutches. A sheet feeding operation to be sent out from the sheet receiving unit is executed. At least some of the plurality of sheet supply units are cassette type sheet supply units. The cassette type sheet supply unit includes a sheet cassette and a cassette detection sensor. The sheet cassette is the sheet receiving portion that is detachably attached to a housing and can accommodate a plurality of recording sheets. The cassette detection sensor is a sensor that detects whether or not the sheet cassette is attached to the housing. The sheet supply roller of the cassette type sheet supply unit is disposed closer to the end of the sheet cassette mounted on the housing on the side in the drawing direction. The control unit can execute delay control when the cassette type sheet supply unit performs the sheet supply operation. The delay control is performed continuously with the output timing of the control signal when the first recording sheet is sent after the cassette detection sensor of the cassette type sheet supply unit detects the mounting of the sheet cassette. In other words, the control is delayed from the output timing of the control signal when the second and subsequent recording sheets are sent out by the same cassette type sheet supply unit.

  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 including a plurality of the sheet supply units including at least a part of the cassette type sheet supply unit. The control method outputs the control signal to each of the sheet supply units by outputting the control signal at a timing based on the occurrence of a supply start event for each recording sheet for each of the supply clutches. 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. In the determination step, when the cassette type sheet supply unit performs the sheet supply operation, the sheet supply operation is performed after the cassette detection sensor of the cassette type sheet supply unit detects attachment of the sheet cassette. This is a step of determining whether or not it is an initial supply operation for sending the first recording sheet. In the delay control step, when the result of the determination step is the initial supply operation, the output timing of the control signal when the first recording sheet is sent out by the cassette type sheet supply unit is continuously provided. Then, it is a step of delaying the output timing of the control signal when the second and subsequent recording sheets are sent out by the same cassette type sheet supply unit.

  According to the present invention, in the case where a displacement of the recording sheet can occur when the drawer-type sheet cassette is mounted on the housing, the occurrence of variations in the time for the recording sheet to reach the sheet detection sensor is prevented as much as possible. It is possible to provide a sheet supply apparatus that can continuously supply recording sheets at short time intervals, an image forming apparatus including the sheet supply apparatus, 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 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 cassette detection sensor 802, and A control unit 8 is provided. Further, the image forming apparatus 10 includes a remaining sheet sensor 803 and the like.

  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. FIG. 1 shows 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 sections 22 includes a first sheet supply roller 221, a second sheet supply roller 222, and a retard roller 223. The second sheet supply roller 222 is disposed to face the retard roller 223.

  The first sheet supply roller 221 and the second sheet supply roller 222 are rotated in contact with the recording sheet 9 so that the recording sheet 9 is provided from the sheet receiving portion 21 to the sheet detection sensor 801. It is a roller that feeds out toward the conveyance path 30.

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

  Further, the second sheet supply roller 222 further sends out the recording sheet 9 sent from the first sheet supply 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 first sheet supply roller 221, the second 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 shown in FIG. 1, the two sheet supply units 2 are cassette-type sheet supply units 2a. The cassette type sheet supply unit 2a includes a sheet cassette 21a and a cassette detection sensor 802a in addition to the sheet delivery unit 22. Further, it is conceivable that the cassette type sheet supply unit 2 a includes a remaining sheet sensor 803.

  The sheet cassette 21 a is a sheet receiving portion 21 that is detachably attached to the casing 100 that forms the exterior, and can accommodate a plurality of the recording sheets 9. Hereinafter, the drawing direction of the sheet cassette 21a is referred to as a cassette drawing direction R1.

  The cassette detection sensor 802 is a sensor that detects whether or not the sheet cassette 21 a is attached to the housing 100. The cassette detection sensor 802 is, for example, a reflection type photo sensor, a transmission type photo sensor, or a limit switch.

  The sheet feeding section 22 of the cassette type sheet supply section 2a is disposed closer to the end on the cassette pulling direction R1 side with respect to the sheet cassette 21a mounted on the casing 100. The sheet feeding unit 22 (the first sheet feeding roller 221 and the second sheet feeding roller 222) feeds the recording sheet 9 stored in the sheet cassette 21a obliquely upward from the cassette pulling direction R1 side.

  The remaining sheet sensor 803 is a sensor that detects the remaining amount of the recording sheet 9 in the sheet cassette 21a. For example, the remaining sheet sensor 803 is a reflective optical sensor that irradiates light to the lower surface of the mounting plate 211 on which the recording sheet 9 is mounted. The inclination angle of the mounting plate 211 increases as the remaining amount of the recording sheet 9 decreases. The optical sensor (the remaining sheet sensor 803) outputs a detection signal that changes according to the inclination angle of the mounting plate 211 described above.

  For example, the control unit 8 specifies the remaining amount of the recording sheet 9 in a plurality of stages such as 25%, 50%, 75%, and 100% according to the level of the detection signal of the remaining sheet sensor 803.

  The remaining one of the three sheet supply units 2 is a manual sheet supply unit 2b. The manual sheet supply unit 2 b includes a manual tray 21 b that is the sheet receiving unit 21 that can be folded with respect to the housing 100.

  Each of the supply clutches 20 has a power (rotational force) for each of the first sheet supply roller 221 and the second sheet supply roller 222 from a drive unit such as a gear driven by a motor in accordance with an input control signal. Is a clutch that selectively switches between a connected state in which the transmission is transmitted and a released state in which the transmission is released. Each of the supply clutches 20 transmits power from the drive unit to each of the first sheet supply roller 221 and the second sheet supply roller 222 via a coupling mechanism (not shown).

  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.

  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 cassette detection sensor 802 and the remaining sheet sensor 803 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.

  As described above, in the sheet supply device of the image forming apparatus 10, the first sheet supply roller 221 and the second sheet supply roller 222 are arranged with respect to the sheet cassette 21 a mounted on the housing 100. It is arranged near the end on the cassette pulling direction R1 side. In this case, when the sheet cassette 21 a is mounted on the housing 100, the upper surface of the recording sheet 9 comes into contact with the first sheet supply roller 221, and the recording sheet 9 is in the sheet feeding direction from the original position. There is a risk of shifting to a downstream position.

  Accordingly, when 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, the recording sheet 9 is transferred from the sheet cassette 21a to the sheet. Variation in time to reach the detection sensor 801 occurs. That is, when the position of the recording sheet 9 is shifted, the recording sheet 9 reaches the position of the sheet detection sensor 801 earlier than when the recording sheet 9 is not.

  For example, when the time variation due to the positional deviation of the recording sheet 9 occurs only under a specific condition, the conveyance interval of the recording sheet 9 is adjusted according to the actual value of the conveyance time of the recording sheet 9. However, the occurrence of the variation 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. Accordingly, even when the recording sheet 9 may be misaligned when the drawer-type sheet cassette 21a is mounted on the housing 100, the occurrence of the time variation is prevented and the time interval is minimized. Recording sheets 9 can be continuously supplied.

[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 sheet supply apparatus of the image forming apparatus 10 will be described with reference to FIG. FIG. 3 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. 3 when, for example, an image forming job is generated by the image forming unit 4. 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, by referring to the contents of the job, the control unit 8 specifies which of the plurality of sheet supply units 2 is the target of the sheet supply operation starting from here. At that time, the control unit 8 determines whether or not the specified sheet supply unit 2 is the cassette type sheet supply unit 2a.

  And the said control part 8 makes a process transfer to the process of step S2-S4 shown below, when the object of the said sheet supply operation | movement is the said cassette type sheet supply part 2a. On the other hand, when the target of the sheet supply operation is not the cassette type sheet supply unit 2a, the control unit 8 shifts the process to step S6 described later.

<Step S2>
In step S2, the control unit 8 performs the sheet supply operation once after the cassette type sheet supply unit 2a to be controlled has detected the last loading of the sheet cassette 21a by the cassette detection sensor 802. It is determined whether or not it is in a state of not being performed.

  That is, the control unit 8 starts the sheet supply operation to be started for the cassette type sheet supply unit 2a to be controlled, and the first recording sheet 9 after the last installation of the sheet cassette 21a is detected. It is determined whether or not the operation is an operation for sending (S2).

  When the upper surface of the recording sheet 9 comes into contact with the first sheet supply roller 221 when the sheet cassette 21a is mounted on the housing 100, the uppermost recording sheet 9 is moved from its original position. Also shifts to a downstream position in the sheet feeding direction. Accordingly, step S2 is a step of determining whether or not the recording sheet 9 to be sent out is a sheet that may be displaced.

<Step S3>
In step S3, the control unit 8 determines whether or not the remaining sheet sensor 803 detects a remaining amount that is equal to or greater than a predetermined amount. The set amount is, for example, 100% or an amount close thereto.

  In general, except when the sheet cassette 21a accommodates the maximum amount or the amount of the recording sheet 9, the upper surface of the recording sheet 9 is the surface when the sheet cassette 21a is mounted on the housing 100. The phenomenon of contacting the first sheet supply roller 221 does not occur. Accordingly, step S3 is a step of determining whether or not there is a high possibility that the recording sheet 9 is shifted to a position downstream of the original position in the sheet feeding direction.

<Step S4>
Further, the control unit 8 determines whether or not the sheet supply operation to be executed by the cassette type sheet supply unit 2a is a continuous switching supply operation that matches a predetermined condition. Steps S1 to S4 are steps (determination steps) in which the MPU 81 executes the operation determination program Pr1.

  When the sheet supply operation to be executed by the cassette type sheet supply unit 2a specified in step S1 is an operation that is continuous with the sheet supply operation of the other sheet supply unit 2 Then, it is determined that the continuous switching supply operation is performed. Here, the continuous operation means that a different sheet supply operation of the sheet supply unit 2 is started within a predetermined short time from the end of the sheet supply operation of a certain sheet supply unit 2. 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 sending out a plurality of the recording sheets 9 while automatically selecting the sheet feeding unit 2 to be subjected to the sheet feeding operation according to a predetermined selection rule. In this case, the sheet supply operation by the sheet supply unit 2 selected after the second in a series of the auto-change control is the continuous switching supply operation.

  For example, the auto-change control is performed when it is detected that the recording sheet 9 of the sheet receiving unit 21 in the first selected sheet supply unit 2 is lost during the job (sheet remaining amount 0%). In the control, the other sheet supply unit 2 is automatically selected to continue the job.

  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

<Step S5>
And when all the determination conditions of step S1-S4 are satisfied, the said control part 8 is longer by the predetermined delay time Td than the predetermined reference adjustment time to the adjustment time variable Ta used for the control mentioned later Set a value representing time. Step S5 is a step in which the MPU 81 executes the delay control program Pr2.

  Note that the case where all the determination conditions in steps S1 to S4 are satisfied means that the sheet supply operation to be performed from now on is the first recording sheet 9 after the sheet cassette 21a is mounted in the cassette type sheet supply unit 2a. And the remaining amount of the recording sheet 9 is equal to or greater than the set remaining amount (YES in S3) and the continuous switching supply operation (YES in S4). It is.

  The situation in which step S5 is executed is a situation in which there is a high possibility that the recording sheet 9 is displaced downstream in the sheet feeding direction at the start of the sheet feeding operation.

  The reference adjustment time is predetermined for each sheet supply unit 2. The delay time Td is a time required to send the recording sheet 9 by the length of the maximum positional deviation of the recording sheet 9 that is assumed.

<Step S6>
On the other hand, if any of the determination conditions in steps S1 to S4 is not satisfied, the control unit 8 sets a value representing the reference adjustment time in the adjustment time variable Ta. Step S6 is a step in which the MPU 81 executes the non-delay control program Pr3.

<Steps S7 to S9>
Then, the control unit 8 monitors the occurrence of the supply start event (S7). 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. The state is set (S8). Further, the control unit 8 returns the supply clutch to the released state after a predetermined time (S9). 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 S7 to S9, one recording sheet 9 is sent out from the sheet receiving unit 21 toward the conveyance path 30. Steps S7 to S9 are steps in which the MPU 81 executes the clutch control signal output program Pr4.

  In addition, the process of step S1-S2 which the said control part 8 performs is a process including the said determination process. In the determination step, when the cassette type sheet supply unit 2a executes the sheet supply operation, the sheet supply operation is performed by the cassette detection sensor 802 of the cassette type sheet supply unit 2a. It is a step of determining whether or not it is an initial supply operation for sending the first recording sheet after detection.

  Moreover, the process of step S5-S9 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 initial supply operation, the output timing of the control signal when the first recording sheet 9 is sent out by the cassette type sheet supply unit 2a, Subsequently, it is a step of delaying the output timing of the control signal when the second and subsequent recording sheets 9 are sent out by the same cassette type sheet supply unit 2a.

<Step S10>
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 S10 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 S10 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 S10 every elapse of a fixed 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 is set to send the first recording sheet 9 after at least the sheet cassette 21a is mounted. It is changed depending on whether or not it is the initial supply operation.

  As a result, even when the uppermost recording sheet 9 is displaced when the sheet cassette 21a is mounted on the housing 100, the time for the recording sheet 9 to reach the sheet detection sensor 801 is reached. It can prevent variation. 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.

  The control unit 8 sets the delay time Td only when the sheet supply operation in the cassette type sheet supply unit 2a is limited to the initial 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.

  Further, when the control unit 8 determines one or both of the conditions of Step S3 and Step S4 in addition to the conditions of Steps S1 and S2, the possibility that the recording sheet 9 is misaligned is higher. Only the delay control is executed. As a result, the frequency with which the recording sheet 9 can be supplied at short time intervals is further increased.

  For example, the control unit 8 executes the delay control step only when the remaining sheet sensor 803 detects the remaining amount equal to or larger than the set amount by determining the condition in step S3.

  Further, when the control unit 8 determines the condition of step S4 to cause the cassette-type sheet supply unit 2a to execute the sheet supply operation, the sheet supply operation is performed by the other sheet supply unit 2 The delay control step is executed only when the operation is continuous with the sheet supply operation. In this case, it is conceivable that the control unit 8 executes the delay control process when the auto change control is performed.

[Other application examples]
The procedure of the control process shown in FIG. 3 is merely an example, and it is conceivable that the control process is performed by another procedure. For example, steps S1 to S4 may be performed in another order, or one or both of steps S3 and S4 may be omitted.

  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 2a: Cassette type sheet feeding unit 2b: Manual sheet feeding unit 3: Sheet feeding 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 21a: Sheet cassette 21b: Manual feed tray 22: Sheet feeding unit 30: Conveying path 31: Registration roller 32: Conveying roller 33: Discharging roller 40: Toner container 41: Photoconductor 42: Charging unit 43: Development 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 placement section 122: Conveying roller 123: Paper discharge tray 211: Placement plate 221: First sheet supply roller 222: Second sheet supply roller 223: Retard roller 801: Sheet detection sensor 802: Cassette detection sensor 802a: Cassette detection sensor 803: sheet remaining amount sensor 2200: movable support portion Pr1: operation determination program Pr2: delay control program Pr3: non-delay control program Pr4: clutch control signal output program Pr5: standby determination program R1: cassette drawing direction

Claims (6)

A sheet receiving portion on which a plurality of recording sheets can be stacked, and a recording path provided with a sensor for detecting the recording sheet from the sheet receiving portion by rotating in contact with the recording sheet. A plurality of sheet supply units each including a supply roller that selectively switches between a state in which power is transmitted from the drive unit to the sheet supply roller according to an input control signal and a state in which the transmission is released in accordance with an input control signal; ,
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 supply units. A control unit that executes a sheet supply operation to be performed,
At least some of the plurality of sheet supply units are
A sheet cassette that is the sheet receiving unit that is mounted so as to be able to be pulled out from the housing and can store a plurality of the recording sheets;
A cassette detection sensor for detecting whether or not the sheet cassette is mounted on the housing;
The sheet supply roller disposed near the end of the sheet cassette mounted on the housing on the side in the pulling direction, and a cassette type sheet supply unit comprising:
The control unit, when causing the cassette type sheet supply unit to execute the sheet supply operation, records the first sheet after the cassette detection sensor of the cassette type sheet supply unit detects attachment of the sheet cassette. Delay control for delaying the output timing of the control signal when the sheet is sent out from the output timing of the control signal when the second and subsequent recording sheets are sent by the same cassette type sheet supply unit. A sheet feeding apparatus capable of performing The cassette type sheet supply unit includes a remaining sheet sensor for detecting the remaining amount of the recording sheet in the sheet cassette,
The sheet feeding apparatus according to claim 1, wherein the control unit executes the delay control only when the remaining sheet sensor detects a remaining amount equal to or greater than a predetermined amount.   When the sheet feeding operation is performed by the cassette type sheet feeding unit, the control unit performs the delay control only when the sheet feeding operation is an operation continuous with the sheet feeding operation of the other sheet feeding unit. The sheet supply apparatus according to claim 1 or 2, wherein   The controller is configured to perform auto-change control in which a plurality of the recording sheets are continuously sent out while automatically selecting the sheet supply unit to be subjected to the sheet supply operation according to a predetermined selection rule. The sheet feeding apparatus according to claim 3, wherein delay control is executed. The sheet feeding apparatus according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming unit that forms an image on the recording sheet supplied from the sheet supply unit of the sheet supply device. A sheet receiving portion on which a plurality of recording sheets can be stacked, and a recording path provided with a sensor for detecting the recording sheet from the sheet receiving portion by rotating in contact with the recording sheet. A plurality of sheet supply units each including a sheet supply roller that feeds out and a supply clutch that selectively switches between a state where power is transmitted from the drive unit to the sheet supply roller according to an input control signal and a state where the transmission is released Prepared,
At least some of the plurality of sheet supply units are
A sheet cassette that is the sheet receiving unit that is mounted so as to be able to be pulled out from the housing and can store a plurality of the recording sheets;
A cassette detection sensor for detecting whether or not the sheet cassette is mounted on the housing;
A control method of a sheet supply apparatus, which is a cassette-type sheet supply unit, comprising: the sheet supply roller disposed near an end of the sheet cassette mounted on the housing on the side in the pulling direction side;
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 supply units. A control step for causing the control unit to execute the sheet supply operation to be performed,
The control step includes
When causing the cassette type sheet supply unit to execute the sheet supply operation, the sheet supply operation is performed after the first sheet is detected after the cassette detection sensor of the cassette type sheet supply unit detects the attachment of the sheet cassette. A determination step of determining whether or not the initial supply operation of sending a recording sheet;
When the result of the determination step is the initial supply operation, the output timing of the control signal when the first recording sheet is sent out by the cassette type sheet supply unit is continuously the same cassette type. And a delay control step of delaying the output timing of the control signal when the second and subsequent recording sheets are sent out by the sheet supply unit.

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