JP7180365B2 - IMAGE FORMING APPARATUS, CONTROL METHOD AND PROGRAM - Google Patents

Description

The present invention relates to an image forming apparatus, control method and program.

2. Description of the Related Art Conventionally, an image forming apparatus has a registration section that performs sheet skew correction. For example, the registration section includes a pair of registration rollers, and generally performs sheet skew correction by pressing the leading edge of the sheet against the nip portion of the pair of registration rollers to form a sheet loop. target.

Further, conventionally, as a configuration of a registration section in an image forming apparatus, there is known a configuration in which skew correction is performed immediately before a sheet is conveyed to a pair of timing rollers (for example, Japanese Patent Application Laid-Open No. 2002-200013). In this prior art, skew correction of a sheet is performed by a shutter member having a swinging fulcrum provided upstream of a pair of timing rollers. That is, in this prior art, when the shutter member is in the standby state, the tip of the shutter member crosses the conveying path of the sheet at an angle and does not guide the sheet to the nip portion of the pair of timing rollers. In this standby state, the shutter member corrects skew of the sheet by bringing the leading edge of the sheet conveyed from the upstream side into contact with the surface of one timing roller of the pair of timing rollers. . When the skew correction of the sheet is completed, the shutter member swings around the swinging fulcrum due to the stiffness of the sheet, opens the entrance to the nip portion of the pair of timing rollers, and guides the sheet to the nip portion.

Further, the conventional image forming apparatus temporarily stops the sheet conveying operation when the leading edge of the sheet is guided to the nip portion of the pair of timing rollers (including the registration rollers). Then, the sheet is supplied to the image transfer position by starting to drive the pair of timing rollers at the timing when the image formed in the image forming unit reaches the predetermined image transfer position. In order to perform such an operation, the conventional image forming apparatus has a sheet detection sensor arranged upstream of the registration section. Temporarily stopping the conveying operation is performed. Therefore, when the pair of timing rollers starts to be driven, the leading edge of the sheet is always in a fixed position. can be sent to the image transfer position at the timing of

On the other hand, if the sheet detection sensor does not detect the leading edge of the sheet within a predetermined period of time after the start of image formation in the image forming section, the image already formed in the image forming section is transferred to the image transfer position. The sheet cannot be fed in time with the arrival timing. Therefore, conventionally, if the sheet detection sensor does not detect the leading edge of the sheet within a predetermined period of time from the start of image formation, the cleaning operation of the image forming section is performed to remove the already formed image as waste toner. Processing to collect in the box is performed.

The waste toner box is provided adjacent to the image forming section, and collects the waste toner discharged from the toner waste port of the image forming section during the cleaning operation. In addition, the waste toner box is provided with a stirring screw near the toner disposal port. By operating the stirring screw during the cleaning operation, clogging of the waste toner near the toner disposal port can be prevented. ing. Conventionally, in this type of device, a configuration has been proposed in which the drive source for the timing roller and the drive source for the stirring screw are shared in order to reduce costs and reduce the size of the device (for example, Patent Document 2). .

JP 2017-88320 A JP-A-2006-91851

In recent years, from the viewpoint of further cost reduction and space saving, it has been studied to integrally provide a skew correcting member having the same function as the shutter member described above and a timing roller. At this time, it is also being considered to realize a more compact configuration by integrally providing the sheet detection sensor with the timing roller and the skew correcting member. When such a configuration is realized, the sheet detection sensor may be arranged to detect that the sheet has been conveyed to a predetermined position on the downstream side of the timing roller. That is, when the leading edge of the sheet reaches the nip portion between the pair of timing rollers, the sheet detection sensor does not perform sheet detection, and the sheet detection sensor performs sheet detection when the sheet is conveyed further downstream of the timing rollers. It is an arrangement mode that is used.

In the configuration in which the sheet detection sensor detects a sheet conveyed downstream of the timing roller as described above, the sheet detection sensor is detected before a predetermined time elapses after the start of image formation, as in the above-described related art. When the cleaning operation is started when the leading edge of the sheet is not detected, the agitating screw is activated. At this time, if the driving source of the stirring screw is common to the timing roller, the timing roller will be driven along with the start of the cleaning operation.

However, even when the leading edge of the sheet is not detected by the sheet detection sensor, the leading edge of the sheet may have already reached the nip portion between the pair of timing rollers. When the timing rollers are driven in such a situation, the sheet sandwiched between the pair of timing rollers is conveyed downstream. In other words, a phenomenon occurs in which the sheet is conveyed downstream during the cleaning operation. Such a phenomenon is a problem because it causes frequent buckling of sheets and jams (paper jams).

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. An object of the present invention is to provide an image forming apparatus, a control method, and a program capable of reducing the frequency.

In order to achieve the above object, the invention according to claim 1 is an image forming apparatus, comprising registration means for correcting the skew of a sheet and conveying the sheet to the downstream side; detection means for detecting a sheet conveyed downstream of the registration means by the registration means; image forming means for transferring a toner image; waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means; agitating means for agitating the waste toner accumulated in the waste toner accumulating means; driving means for driving the registration means and the stirring means in conjunction with each other; and control means for controlling the driving means, wherein the control means controls a predetermined When the sheet is not detected by the detecting means before the time elapses, the driving means is stopped, and the toner image is collected by the image forming means in a state in which the stirring means is not operated, and is transferred to the waste toner accumulating means. The configuration is characterized by performing a leading cleaning operation .

According to a second aspect of the invention, in the image forming apparatus according to the first aspect, when the sheet is not detected by the detecting means before the predetermined time elapses, the sheet is held in the image forming means. In this configuration, the driving means is stopped and the cleaning operation is performed when the toner amount of the applied toner image is equal to or less than a predetermined amount .

The invention according to claim 3 is the image forming apparatus according to claim 2 , wherein the image forming means has a photosensitive drum for forming a toner image on its surface, and the control means controls the toner image on the photosensitive drum. This configuration is characterized in that it is determined whether or not the toner amount of the held toner image is equal to or less than a predetermined amount .

The invention according to claim 4 is the image forming apparatus according to claim 2 , wherein the image forming means has an intermediate transfer belt that conveys the toner image to the predetermined position, and the control means controls the intermediate transfer belt The configuration is characterized in that it is determined whether or not the toner amount of the toner image held thereon is equal to or less than a predetermined amount .

A fifth aspect of the invention is directed to the image forming apparatus according to the second aspect, wherein the image forming means comprises a photosensitive drum for forming a toner image on its surface, and a toner image transferred from the photosensitive drum. and an intermediate transfer belt that conveys the intermediate transfer belt to a position, and the control means determines whether or not the toner amount of the toner image held on both the photosensitive drum and the intermediate transfer belt is equal to or less than a predetermined amount. It is a configuration characterized by judging.

The invention according to claim 6 is the image forming apparatus according to any one of claims 2 to 5 , wherein the control means detects the amount of toner based on the number of toner images held in the image forming means. It is a configuration characterized by

The invention according to claim 7 is the image forming apparatus according to any one of claims 2 to 6 , wherein the control means detects the toner amount based on the coverage of the toner image held in the image forming means. It is a configuration characterized by

The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7 , wherein when the sheet is not detected by the detection means before the predetermined time elapses, the control means In this configuration, the driving means is stopped and the cleaning operation is performed when the amount of waste toner accumulated in the waste toner accumulation means is equal to or less than a predetermined amount.

( 9 ) The image forming apparatus according to any one of (1) to (8) , wherein the control means operates the driving means after the cleaning operation in the image forming means is finished. It is a configuration.

According to a tenth aspect of the invention, in the image forming apparatus according to the ninth aspect, the control means causes the image forming means to resume the toner image forming operation after the cleaning operation in the image forming means is finished. It is a configuration characterized by

<11> The image forming apparatus according to <10> , wherein the control means controls the detection until the predetermined time elapses after the toner image forming operation is restarted in the image forming means. The arrangement is characterized in that the drive means is stopped again when no sheet is detected by the means.

( 12 ) In the image forming apparatus according to ( 10) or (11) , the control means controls the image forming means until the predetermined time elapses after the toner image forming operation is restarted in the image forming means. The configuration is characterized in that the driving means is continuously operated when the sheet is detected by the detecting means.

According to a thirteenth aspect of the invention, there is provided an image forming apparatus, comprising: registration means for performing skew correction of a sheet and conveying the sheet to a downstream side; image formation for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream passes a predetermined position by the resist means; means, waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means, agitating means for agitating the waste toner accumulated in the waste toner accumulating means, the resist means and the agitating means. A drive unit that drives in conjunction with the drive unit and a control unit that controls the drive unit are provided, and the control unit controls the image forming unit to control the toner image before a predetermined time elapses after the start of toner image formation in the image forming unit. When the sheet is not detected by the detecting means and the toner amount of the toner image held in the image forming means is equal to or less than a predetermined amount, the driving means is stopped to cause the image forming means to collect the toner image. to perform a cleaning operation leading to the waste toner storage means, and if the toner amount of the toner image held in the image forming means is not equal to or less than the predetermined amount, the driving means is continuously operated to cause the image forming means to operate. is configured to perform the cleaning operation.

A fourteenth aspect of the present invention is the image forming apparatus according to the thirteenth aspect, wherein the control means continuously operates the driving means to cause the image forming means to perform the cleaning operation. The configuration is characterized in that the driving means is stopped when the sheet is detected by the detecting means.

A fifteenth aspect of the present invention is the image forming apparatus according to the thirteenth aspect or the fourteenth aspect , wherein the control means causes the image forming means to perform the cleaning operation by continuously operating the driving means. In this configuration, when the cleaning operation ends without the sheet being detected by the detecting means, the image forming means restarts the toner image forming operation.

According to a sixteenth aspect of the present invention, registration means for performing sheet skew correction and conveying the sheet to the downstream side, and detection of the sheet conveyed downstream by the registration means after the sheet skew correction is performed. detection means, image forming means for forming and holding a toner image, and transferring the toner image when the sheet conveyed downstream of the registration means by the registration means passes a predetermined position, and the image formation means. waste toner accumulating means for collecting and accumulating waste toner remaining in the waste toner accumulating means; stirring means for stirring the waste toner accumulated in the waste toner accumulating means; and driving means for driving the resist means and the stirring means in conjunction with each other. and a first step of operating the driving means and causing the image forming means to start a toner image forming operation; a second step of determining whether or not the sheet is detected by the detecting means before a predetermined time elapses after the image forming operation is started; is not detected, the driving means is stopped, and the image forming means is caused to collect the toner image in a state in which the agitating means is not operated, and perform a cleaning operation leading to the waste toner accumulating means. and a step.
According to a seventeenth aspect of the present invention, registration means for performing sheet skew correction and conveying the sheet downstream, and detection of the sheet conveyed downstream by the registration means after the sheet skew correction is performed. detection means, image forming means for forming and holding a toner image, and transferring the toner image when the sheet conveyed downstream of the registration means by the registration means passes a predetermined position, and the image formation means. waste toner accumulating means for collecting and accumulating waste toner remaining in the waste toner accumulating means; stirring means for stirring the waste toner accumulated in the waste toner accumulating means; and driving means for driving the resist means and the stirring means in conjunction with each other. and a first step of operating the driving means and causing the image forming means to start a toner image forming operation; a second step of determining whether or not the sheet is detected by the detecting means before a predetermined time elapses after the image forming operation is started; is not detected and the toner amount of the toner image held in the image forming means is equal to or less than a predetermined amount, the driving means is stopped and the toner image is collected by the image forming means. cleaning operation leading to the waste toner storage means, and when the toner amount of the toner image held in the image forming means is not equal to or less than the predetermined amount, the driving means is continuously operated to form the image. and a third step of causing the means to perform the cleaning operation.

According to an eighteenth aspect of the present invention, registration means for performing sheet skew correction and conveying the sheet downstream, and detection of the sheet conveyed downstream by the registration means after the sheet skew correction is performed. detection means, image forming means for forming and holding a toner image, and transferring the toner image when the sheet conveyed downstream of the registration means by the registration means passes a predetermined position, and the image formation means. waste toner accumulating means for collecting and accumulating waste toner remaining in the waste toner accumulating means; stirring means for stirring the waste toner accumulated in the waste toner accumulating means; and driving means for driving the resist means and the stirring means in conjunction with each other. and a program executed in an image forming apparatus comprising: a first step of causing the image forming apparatus to operate the driving means and causing the image forming means to start a toner image forming operation; a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started by the step; When it is determined that the sheet has not been detected before the predetermined time elapses, the driving means is stopped, and the toner image is collected by the image forming means in a state in which the stirring means is not operated, and is transferred to the waste toner accumulating means. and a third step of performing a leading cleaning operation .
According to a nineteenth aspect of the present invention, registration means for performing sheet skew correction and conveying the sheet downstream, and detection of the sheet conveyed downstream by the registration means after the sheet skew correction is performed. detection means, image forming means for forming and holding a toner image, and transferring the toner image when the sheet conveyed downstream of the registration means by the registration means passes a predetermined position, and the image formation means. waste toner accumulating means for collecting and accumulating waste toner remaining in the waste toner accumulating means; stirring means for stirring the waste toner accumulated in the waste toner accumulating means; and driving means for driving the resist means and the stirring means in conjunction with each other. and a program executed in an image forming apparatus comprising: a first step of causing the image forming apparatus to operate the driving means and causing the image forming means to start a toner image forming operation; a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started by the step; When it is determined that the sheet has not been detected before the predetermined time elapses, and the toner amount of the toner image held in the image forming means is equal to or less than the predetermined amount, the driving means is stopped and the image is formed. The forming means is caused to collect the toner image and perform a cleaning operation leading to the waste toner accumulation means, and if the toner amount of the toner image held in the image forming means is not equal to or less than the predetermined amount, the driving means is continued. and a third step of causing the image forming means to perform the cleaning operation by operating the image forming means.

According to the present invention, in the configuration in which the detecting means for detecting the sheet detects the sheet conveyed to the downstream side of the registering means, if the detecting means does not detect the sheet before the predetermined time elapses, the seat position of the sheet is detected. It is possible to suppress the occurrence of bending and jamming.

1 is a diagram illustrating a configuration example of an image forming apparatus; FIG. 2 is a diagram showing the internal structure of the image forming apparatus on the side of the image forming section; FIG. It is a figure which shows an example of the drive mechanism of a registration part and a stirring screw. It is a figure which shows one structural example of a registration part. FIG. 5 is a plan view for explaining the concept of sheet skew correction; FIG. 5 is a plan view for explaining the concept of sheet skew correction; It is a figure which shows the state which the gate member displaced to the 2nd attitude|position. It is a side view which shows the attitude|position change of a gate member. 3 is a block diagram showing an example of the hardware configuration and functional configuration of a controller; FIG. 4 is a flow chart showing an example of a main processing procedure performed by a controller; 7 is a flowchart illustrating an example of detailed processing procedures of retry processing in the first embodiment; FIG. 11 is a flow chart showing an example of a detailed processing procedure of retry processing in the second embodiment; FIG. FIG. 12 is a flowchart showing an example of detailed processing procedures of retry processing in the third embodiment; FIG. 7 is a flowchart showing an example of detailed processing procedures of normal cleaning processing; It is a figure which shows the modification regarding the arrangement position of a sensor.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Elements common to each other in the embodiments described below are denoted by the same reference numerals, and redundant description thereof will be omitted.

(First embodiment)
FIG. 1 is a diagram showing a configuration example of an image forming apparatus 1 that is an embodiment of the present invention. An image forming apparatus 1 shown in FIG. 1 is a printer that forms an image on a sheet 9 such as printing paper by an electrophotographic method, and is an apparatus capable of forming a color image by a tandem method. The image forming apparatus 1 includes a conveying section 2, an image forming section 3, and a fixing section 4 inside the main body of the apparatus, and conveys sheets 9 accommodated in a paper feeding cassette 8 one by one. , a color image or a monochrome image is formed on the sheet 9, and the sheet 9 is discharged onto the discharge tray 6 from the upper discharge port 5. FIG. The image forming apparatus 1 also includes a controller 7 inside the apparatus main body. The controller 7 controls the operations of each section such as the conveying section 2 , the image forming section 3 and the fixing section 4 .

The transport section 2 includes a paper feed cassette 8 , a pickup roller 10 , a paper feed section 11 , a transport path 12 , a registration section 15 and a secondary transfer roller 25 . The paper feed cassette 8 is a container that accommodates a bundle of sheets 9 . The pickup roller 10 picks up the uppermost sheet 9 from the stack of sheets 9 contained in the sheet feeding cassette 8 and feeds it to the sheet feeding section 11 . However, the pickup roller 10 may send out a plurality of sheets 9 to the downstream side of the paper feed cassette 8 . The paper feeding unit 11 extracts only one sheet 9 positioned at the top from one or a plurality of sheets 9 delivered by the pickup roller 10 and supplies the sheet 9 to the downstream conveying path 12 .

The transport path 12 is a path for transporting the sheet 9 in the arrow F2 direction. The sheet 9 conveyed along the conveying path 12 undergoes skew correction in the registration section 15 . The registration unit 15 includes a pair of timing rollers 32 and 34, and drives at least one timing roller 32 of the pair of timing rollers 32 and 34 to rotate. The registration unit 15 corrects the skew of the sheet 9 on the upstream side of the pair of timing rollers 32 and 34 and then holds the leading edge of the sheet 9 at the nip portion between the pair of timing rollers 32 and 34 . When the leading edge of the sheet 9 is held by the nip portion of the pair of timing rollers 32 and 34 , the conveying portion 2 temporarily stops conveying the sheet 9 . Then, the registration unit 15 drives the pair of timing rollers 32 and 34 in synchronization with the timing at which the toner image formed by the image forming unit 3 moves to the position of the secondary transfer roller 25, and transfers the sheet 9 to the secondary transfer roller. It is conveyed to the position of roller 25 . The toner image is transferred to the sheet 9 when passing through the nip position of the secondary transfer roller 25 , and then the toner image transferred to the paper surface is subjected to fixing processing when passing through the fixing unit 4 . The fixing unit 4 fixes the toner image to the sheet 9 by applying heat and pressure to the conveyed sheet 9 . After that, the sheet 9 is ejected from the ejection port 5 onto the paper ejection tray 6 .

The image forming unit 3 forms a four-color toner image of Y (yellow), M (magenta), C (cyan), and K (black) on the sheet 9 passing through the position of the secondary transfer roller 25 . The configuration is such that the toner images of these four colors can be transferred simultaneously. The image forming section 3 includes an exposure unit 20, image forming units 21 (21Y, 21M, 21C, 21K) provided for each color toner, and primary transfer rollers 22 (22Y , 22M, 22C, 22K). The four image forming units 21Y, 21M, 21C, and 21K are provided below the intermediate transfer belt 24, and the exposure unit 20 is provided below the four image forming units 21Y, 21M, 21C, and 21K. ing. The toner bottles 23Y, 23M, 23C and 23K supply toner of each color to each of the four image forming units 21Y, 21M, 21C and 21K.

Each image forming unit 21 has a cylindrical photosensitive drum, forms and holds a toner image on the surface of the photosensitive drum, and primarily transfers the toner image onto an intermediate transfer belt 24 . Each image forming unit 21 also includes a cleaner section 28 for collecting toner remaining on the surface of the photosensitive drum.

The intermediate transfer belt 24 is an endless belt suspended between a pair of rollers 26 and 27, and circulates in the arrow F1 direction. The intermediate transfer belt 24 is provided with a cleaner section 29 for collecting toner remaining on the belt surface at a predetermined position on the upstream side of each image forming unit 21 .

The exposure unit 20 forms a latent image on the photosensitive drum of each image forming unit 21 by exposing the photosensitive drum provided in each image forming unit 21 . Each image forming unit 21 forms a toner image on the surface of the photosensitive drum by developing the latent image with toner. Each image forming unit 21 cooperates with the primary transfer roller 22 to sequentially superimpose the toner image of each color onto the intermediate transfer belt 24 while performing primary transfer. Therefore, when the intermediate transfer belt 24 passes the position of the most downstream image forming unit 21K, a color image is formed on the surface of the intermediate transfer belt 24 by superimposing four color toner images. The toner image formed on the intermediate transfer belt 24 comes into contact with the sheet 9 conveyed by the conveying unit 2 when passing through a position facing the secondary transfer roller 25, and is secondarily transferred onto the surface of the sheet 9. be.

FIG. 2 is a diagram showing the internal structure of the image forming apparatus 1 on the side of the image forming section 3. As shown in FIG. As shown in FIG. 2, the image forming apparatus 1 includes a waste toner box 70 adjacent to the side of the image forming section 3 inside the image forming apparatus 1 . The waste toner box 70 is a waste toner accumulation unit that collects and accumulates waste toner collected by the image forming section 3 when the image forming section 3 performs a cleaning operation. A toner disposal port 71 is provided on the upper portion of the waste toner box 70 at a position corresponding to the cleaner portion 29 of the intermediate transfer belt 24 , and a toner disposal port 71 is provided at a position corresponding to the cleaner portion 28 of each image forming unit 21 . 72 are provided.

When the cleaning operation is performed in the image forming section 3 , the cleaner section 29 provided on the intermediate transfer belt 24 collects the toner remaining on the surface of the intermediate transfer belt 24 as waste toner, and the waste toner is discharged through the toner disposal port 71 . to the inside of the waste toner box 70 . Similarly, when the cleaning operation is performed in the image forming section 3, the cleaner section 28 provided in each image forming unit 21 collects the toner image held on the surface of the photoreceptor drum as waste toner, and collects the waste toner. is discharged inside the waste toner box 70 from the toner disposal port 72 .

The waste toner box 70 has a stirring screw 73 near the toner disposal ports 71 and 72 . The agitation screw 73 agitates the waste toner discharged from the toner disposal ports 71 and 72 by rotating around its rotary shaft 73 a , and uniformizes the accumulated state of the waste toner inside the waste toner box 70 . As a result, clogging of waste toner in the vicinity of the toner disposal ports 71 and 72 can be prevented.

The stirring screw 73 is driven by the same driving source as the timing roller 32 of the registration section 15 . That is, in the image forming apparatus 1, the driving source of the stirring screw 73 and the driving source of the timing roller 32 of the registration section 15 are shared, and the stirring screw 73 and the timing roller 32 are simultaneously driven by one driving source. By doing so, the size and cost of the device can be reduced.

FIG. 3 is a diagram showing an example of a drive mechanism for the registration section 15 and the stirring screw 73. As shown in FIG. The registration unit 15 is installed at a predetermined position on the upstream side of the secondary transfer roller 25 in the transport path 12 and includes a plurality of timing rollers 32 and 34 arranged to face each other with the transport path 12 of the sheet 9 interposed therebetween. ing. The plurality of timing rollers 32, 34 are each paired with each other. The timing roller 32 is attached to the rotating shaft 31 . One end of the rotating shaft 31 is connected to a motor 18 as a drive source for rotating the timing roller 32 . A link mechanism 19 is provided at the other end of the rotating shaft 31 .

On the other hand, a link mechanism 19 is also provided at one end of the rotating shaft 73 a of the stirring screw 73 . That is, the stirring screw 73 is connected to the rotation shaft 31 of the timing roller 32 via the link mechanism 19 and is rotated in a predetermined direction by the torque of the motor 18 . For example, the link mechanism 19 holds the gear 73a provided at the end of the rotating shaft 73a of the stirring screw 73 and the gear 31d provided at the end of the rotating shaft 31 of the timing roller 32 in a mutually engaged state. Thereby, the driving force of the motor 18 is transmitted to the stirring screw 73 . Further, the link mechanism 19 may be configured to transmit the driving force of the motor 18 to the stirring screw 73 via a one-way clutch or the like that rotates the stirring screw 73 in only one direction.

Therefore, the image forming apparatus 1 of the present embodiment is configured such that when the motor 18 is driven to rotate the timing roller 32 of the registration section 15, the stirring screw 73 rotates accordingly. Conversely, when the motor 18 is driven to rotate the stirring screw 73 inside the waste toner box 70, the timing roller 32 is also rotated accordingly.

Next, details of the resist section 15 will be described. FIG. 4 is a diagram showing a configuration example of the resist section 15. As shown in FIG. The paper feed unit 11 includes a plurality of paper feed rollers 11a and 11b arranged to face each other with the transport path 12 interposed therebetween. Carry 9. The sheet feeding section 11 is positioned upstream of the registration section 15 in the conveying path 12 of the sheet 9 , and conveys the sheet 9 fed by the sheet feeding rollers 11 a and 11 b toward the registration section 15 . Further, another transport roller may be arranged between the paper feeding section 11 and the registration section 15 .

Of the pair of timing rollers 32 and 34, the registration unit 15 uses one timing roller 32 as a driving roller and the other timing roller 34 as a driven roller. As mentioned above, the timing roller 32 is mounted on the rotating shaft 31 driven by the motor 18 and rotates therewith when the rotating shaft 31 rotates. Such timing rollers 32 are provided at a plurality of locations (four locations in this embodiment) at predetermined intervals along the axial direction of the rotating shaft 31 . On the other hand, the timing roller 34 is mounted on the rotating shaft 33 and rotates together with the rotating shaft 33 . The timing rollers 34 are also provided at a plurality of locations (four locations in this embodiment) at predetermined intervals along the axial direction of the rotating shaft 33, and are provided at the same positions as the timing rollers 32 in the axial direction. The registration unit 15 rotates the pair of timing rollers 32 and 34 by driving the timing roller 32 in a state in which the sheet 9 is sandwiched between the nip portions of the pair of timing rollers 32 and 34 to move the sheet 9 further downstream. carry to the side.

In the registration section 15, gate members 35a and 35b are freely rotatably mounted at two positions of the rotating shaft 31 on which the timing roller 32 is mounted. Therefore, the gate members 35a and 35b do not rotate together with the rotating shaft 31 and the timing roller 32 even if the rotating shaft 31 and the timing roller 32 are driven to rotate in a predetermined direction, and are independent of the rotating shaft 31 and the timing roller 32. rotatably displaceable around the rotating shaft 31 in the state of being held. The two gate members 35 a and 35 b provided on the rotating shaft 31 are integrally connected by a connecting bar 38 provided at a position where they do not interfere with the timing roller 32 . Therefore, the two gate members 35a and 35b rotate around the rotation shaft 31 together. These gate members 35a and 35b are provided, for example, at symmetrical positions on both sides of the central portion of the rotation shaft 31 in the longitudinal direction, and perform skew correction of the sheet 9. As shown in FIG. That is, the gate members 35 a and 35 b are skew correction members provided in the registration section 15 . In the following description, the two gate members 35a and 35b are collectively referred to as the gate member 35 when there is no need to distinguish between them.

Each of the gate members 35a and 35b has a sheet locking portion 36 that abuts on the leading edge of the sheet 9 to lock the leading edge of the sheet 9. As shown in FIG. Each of the gate members 35a and 35b has a sheet locking portion 36 arranged at a predetermined position upstream of the nip portion between the timing rollers 32 and 34 so that the leading edge of the sheet 9 can be locked to the sheet locking portion 36. 1 posture and a second posture in which the sheet engaging portion 36 is retracted downstream of the nip portion between the timing rollers 32 and 34 to allow the sheet 9 to pass therethrough. The gate members 35a and 35b correct the skew of the sheet 9 before the sheet 9 is guided to the nip portion between the timing rollers 32 and 34 when the sheet 9 is in the first posture, and after correcting the skew of the sheet 9, the gate members 35a and 35b The sheet 9 is rotationally displaced from the first posture and guided to the nip portion between the timing rollers 32 and 34 .

5 and 6 are plan views for explaining the concept of skew correction of the sheet 9. FIG. First, as shown in FIG. 5, when the sheet 9 is conveyed in an oblique state from the sheet feeder 11, the leading edge of the sheet 9 is first engaged with one of the two gate members 35a and 35b. It abuts against the stop portion 36 . When the tip of the sheet 9 is in contact with only the sheet locking portion 36 of one of the two gate members 35a and 35b, the sheet 9 can push the sheet locking portion 36. Therefore, the leading edge of the seat 9 locked by the seat locking portion 36 stays at that position.

After that, the sheet feeding unit 11 continues to convey the sheet, and when the succeeding portion of the sheet 9 further advances in the conveying direction, as shown in FIG. The other gate member 35b is also brought into contact with the sheet engaging portion 36 of the other gate member 35b. When the leading edge of the sheet 9 is locked by the sheet locking portions 36 of both of the two gate members 35a and 35b, the skew correction of the sheet 9 is completed. At this time, since the conveying force of the paper feeding unit 11 and the pressing force due to the stiffness of the sheet 9 itself act evenly on the two sheet locking portions 36, the sheet 9 moves from the sheet locking portion 36 to the downstream side. can be pushed into By pushing the seat locking portion 36 downstream, the gate members 35a and 35b rotate about the rotation shaft 31 and are displaced from the first posture to the second posture. At this time, the motor 18 is already driven to rotate the timing roller 32 . The motor 18 may be driven before the leading edge of the sheet 9 reaches the gate members 35a and 35b. Also good.

FIG. 7 is a diagram showing a state in which the gate members 35a and 35b are displaced to the second posture. When the sheet 9 pushes the sheet engaging portions 36 of the two gate members 35 a and 35 b and advances downstream, the leading edge of the sheet 9 advances to the nip portion between the pair of timing rollers 32 and 34 . On the other hand, the registration unit 15 waits while rotating the timing roller 32 in the R direction by driving the motor 18 . That is, when the leading edge of the sheet 9 advances to the nip portion between the pair of timing rollers 32 and 34, the timing roller 32 is already rotationally driven in the R direction. Therefore, the sheet 9 is sandwiched between the pair of timing rollers 32 and 34, and as shown in FIG. transported to At this time, the gate members 35a and 35b are displaced to the second posture, and the sheet locking portion 36 is retracted to the upper position on the downstream side of the conveying path, thereby allowing the sheet 9 to pass downstream. That is, while the sheet 9 is passing through the registration section 15, the gate members 35a and 35b maintain the second posture.

The registration section 15 has a biasing member 40 for returning the gate members 35a and 35b to the original first posture after the trailing edge of the sheet 9 has passed through the gate members 35a and 35b. The biasing member 40 is composed of, for example, a coil spring, and has one end connected to a fixing portion 41 inside the apparatus and the other end connected to the connecting bar 38 . The biasing member 40 always exerts a biasing force so that the gate members 35a and 35b maintain the first posture. When the gate members 35a and 35b swing and are displaced to the second posture, the biasing member 40 applies a greater biasing force to the gate members 35a and 35b so as to return the gate members 35a and 35b to the first posture. . Then, when the trailing edge of the sheet 9 passes through the gate members 35a and 35b, the biasing member 40 returns the gate members 35a and 35b to the original first posture by the biasing force thereof.

FIG. 8 is a side view showing a change in posture of the gate member 35. As shown in FIG. In FIG. 8A, the gate member 35 holds the first posture. In this first posture, the sheet engaging portion 36 is at a predetermined position on the upstream side of the nip portion 15a of the timing rollers 32 and 34 . The sheet 9 is conveyed to the registration section 15 by the sheet feeding section 11 when the gate member 35 is in the first posture. Then, as shown in FIG. 8B, the leading edge 9a of the sheet 9 is engaged with the two sheet engaging portions 36, so that the skew of the sheet 9 is corrected. The gate member 35 maintains the first posture until this skew correction is completed. When the leading edge 9a of the sheet 9 comes into contact with the two sheet engaging portions 36 and the skew correction is completed, the sheet 9 causes the gate member 35 to rotate. Then, the timing rollers 32 and 34, which are already rotationally driven, pinch the leading edge 9a of the sheet 9 and convey it to the downstream side, whereby the gate member 35 is displaced to the second posture as shown in FIG. 8(c). do. When the gate member 35 is displaced to the second posture, the sheet locking portion 36 moves downstream of the nip portion 15a of the timing rollers 32 and 34, and the sheet 9 can pass therethrough. The gate member 35 maintains the second posture until the trailing edge of the sheet 9 passes. Thereafter, when the rear end of the sheet 9 passes through the gate member 35, the biasing force of the biasing member 40 causes the gate member 35 to return to the first posture shown in FIG. 8(a).

Such a resist section 15 has a sensor 43 for detecting the attitude of the gate member 35 at a position near the gate member 35 . For example, as shown in FIG. 7, the sensor 43 is provided above the gate member 35a. The sensor 43 is arranged independently from the connecting bar 38 and the gate member 35 and is fixed inside the device. Therefore, even if the gate member 35 and the connecting bar 38 are displaced, the position of the sensor 43 does not change.

The sensor 43 detects that the gate member 35 has been displaced to the second posture. In other words, the sensor 43 is detection means for detecting that the leading edge 9 a of the sheet 9 has reached a predetermined position downstream of the timing rollers 32 and 34 . The sensor 43 is composed of, for example, an optical sensor in which a light projecting portion and a light receiving portion are arranged to face each other.

On the other hand, as shown in FIGS. 4 and 7, on the back side of the gate member 35a (downstream side in the conveying direction), the sensor 43 advances and retreats between the light projecting portion and the light receiving portion of the sensor 43 as the attitude of the gate member 35a changes. A light blocking member 39 is provided. The light shielding member 39 rotates around the rotation shaft 31 integrally with the gate member 35 a and advances and retreats between the light projecting portion and the light receiving portion of the sensor 43 . By such forward/backward movement, the light shielding member 39 guides the light emitted from the light projecting portion of the sensor 43 to the light receiving portion or shields the light according to the posture change of the gate member 35 . The sensor 43 detects the posture of the gate member 35 by detecting the light receiving state or light shielding state according to the position of the light shielding member 39 .

For example, when the gate member 35 is in the first posture, the light blocking member 39 does not enter between the light projecting portion and the light receiving portion of the sensor 43 (see FIGS. 8A and 8B). At this time, the sensor 43 detects the light receiving state. On the other hand, when the sheet 9 advances to a predetermined position on the downstream side of the timing rollers 32 and 34 and the gate member 35 is displaced to the second posture, the light blocking member 39 moves between the light projecting portion and the light receiving portion of the sensor 43. (see FIG. 8(c)). At this time, since the sensor 43 transitions from the light receiving state to the light blocking state, it can detect that the sheet 9 has reached a predetermined position on the downstream side of the timing rollers 32 and 34 .

Based on the output from the sensor 43 as described above, the controller 7 detects that the leading edge 9 a of the sheet 9 has reached a predetermined position downstream of the pair of timing rollers 32 and 34 . The controller 7 can temporarily stop the conveyance of the sheet 9 at the timing when it detects that the leading edge 9a of the sheet 9 has reached a predetermined position downstream of the timing rollers 32 and 34 . After that, the controller 7 waits for the timing when the toner image formed by the image forming section 3 moves to the position of the secondary transfer roller 25 , drives the timing roller 32 again, and transfers the sheet 9 to the secondary transfer roller 25 . transport towards.

As described above, the image forming apparatus 1 of the present embodiment is configured such that the gate member 35 having the function of correcting the skew of the sheet 9 , the timing rollers 32 and 34 , and the sensor 43 are integrated as the registration section 15 . The sensor 43 is arranged to detect that the leading edge of the sheet 9 has passed through the nip portion 15a of the timing rollers 32 and 34 and has reached a predetermined position on the downstream side of the timing rollers 32 and 34 . Especially in this embodiment, since the sensor 43 is provided above the gate member 35, the three members of the gate member 35, the timing rollers 32 and 34, and the sensor 43 can be arranged compactly. there is

The controller 7 detects that the leading edge 9a of the sheet 9 reaches a predetermined position on the downstream side of the timing rollers 32 and 34 by the sensor 43 before a predetermined time elapses after the toner image forming operation is started in the image forming section 3. If it is not detected, the drive of the motor 18 is stopped. That is, even if the leading edge 9a of the sheet 9 has not reached a predetermined position downstream of the timing rollers 32 and 34, the leading edge 9a of the sheet 9 may be held in the nip portion between the timing rollers 32 and 34. Therefore, the controller 7 prevents the sheet 9 from buckling or jamming by not driving the motor 18 in such a situation. Details of the control by such a controller 7 will be described below.

FIG. 9 is a block diagram showing an example of the hardware configuration and functional configuration of the controller 7. As shown in FIG. The controller 7 has a CPU 50 and a memory 51 as its hardware configuration. The CPU 50 is an arithmetic processing unit that executes various programs. Memory 51 is a non-volatile storage device that stores program 52 . When the image forming apparatus 1 is powered on, the CPU 50 reads and executes a program 52 pre-stored in the memory 51 . Thereby, the CPU 50 functions as a print control section 53 .

For example, when a print job is received via a communication interface (not shown), the print control unit 53 controls print output based on the print job. For example, when starting execution of a print job, the print control unit 53 drives the conveying unit 2 , the image forming unit 3 , and the fixing unit 4 to perform image formation on the sheet 9 . For example, when starting execution of a print job, the print control unit 53 drives the image forming unit 3 at a predetermined timing to start a toner image forming operation based on the print job. Further, when starting execution of the print job, the print control unit 53 drives the conveying unit 2 at a predetermined timing (paper feeding timing) to start conveying the sheet 9 . At this time, the print control unit 53 starts driving the motor 18 of the registration unit 15 . The timing at which the image forming section 3 starts forming the toner image and the timing at which the conveying section 2 starts conveying the sheet 9 may not necessarily match.

The print control unit 53 determines that the sheet 9 reaches a predetermined position on the downstream side of the timing rollers 32 and 34 by the sensor 43 within a predetermined time after starting the toner image forming operation in the image forming unit 3. When this is detected, the conveying operation by the conveying section 2 is temporarily stopped at that point. After that, the print control unit 53 drives the motor 18 in anticipation of the timing when the toner image formed by the image forming unit 3 moves to the position of the secondary transfer roller 25 , so that the surface of the sheet 9 is properly printed. Control is performed so that the toner image is transferred to the position.

On the other hand, the sensor 43 detects that the sheet 9 has reached a predetermined position on the downstream side of the timing rollers 32 and 34 within a predetermined period of time after the start of the toner image forming operation in the image forming section 3 . If not, sheet 9 will arrive later than the toner image. In this case, the toner image already formed in the image forming section 3 cannot be transferred to an appropriate position on the sheet 9 . Therefore, the print control unit 53 stops driving the transport unit 2 including the motor 18 to interrupt the execution of the job. Then, the print control unit 53 causes the image forming unit 3 to perform the cleaning operation while the conveying unit 2 including the motor 18 is stopped.

When a cleaning operation is instructed by the print control unit 53 while the print job is being executed, the image forming unit 3 interrupts the image forming operation based on the print job and starts the cleaning operation. That is, the image forming section 3 collects the toner image formed on the photosensitive drum of each image forming unit 21 by the cleaner section 28 , and cleans the toner image primarily transferred onto the intermediate transfer belt 24 by the cleaner section 29 . to collect. The image forming section 3 discharges the waste toner collected by the cleaner sections 28 and 29 to the waste toner box 70 .

When the image forming section 3 completes the cleaning operation, the print control section 53 restarts execution of the print job. That is, the print control unit 53 restarts the operation of forming the toner image in the image forming unit 3 and restarts the operation of conveying the sheet 9 by the conveying unit 2 . When the sensor 43 detects that the sheet 9 has reached a predetermined position on the downstream side of the timing rollers 32 and 34 within a predetermined period of time after restarting the toner image forming operation in the image forming section 3. , the print control unit 53 continues execution of the print job, and transfers the sheet 9 to the secondary transfer roller 25 at the timing when the toner image formed by the image forming unit 3 moves to the position of the secondary transfer roller 25 . position. On the other hand, the sensor 43 indicates that the sheet 9 has reached a predetermined position downstream of the timing rollers 32 and 34 within a predetermined period of time after the toner image forming operation in the image forming section 3 is restarted. If no jam is detected, the print control unit 53 determines that a jam has occurred, stops execution of the print job, and issues a warning to the user.

Next, a specific processing procedure performed by the controller 7 will be described. 10 and 11 are flow charts showing an example of a processing procedure performed by the controller 7. FIG. The controller 7 executes the processes shown in FIGS. 10 and 11 based on the program 52 upon starting execution of the print job.

When starting execution of a print job, the controller 7 first determines whether or not it is time to feed paper (step S1). 9 is started (step S2). At this time, the controller 7 also starts driving the motor 18 of the registration section 15 . The controller 7 also drives the image forming section 3 to start the toner image forming operation (step S3). When the toner image forming operation is started, the controller 7 starts the time measuring operation (step S4).

Subsequently, the controller 7 determines whether or not the sensor 43 has detected that the sheet 9 has reached a predetermined position downstream of the timing rollers 32 and 34 (step S5). If the arrival of the sheet 9 is not detected by the sensor 43 (NO in step S5), the controller 7 refers to the time when the measurement was started in step S4, and a predetermined time has elapsed since the toner image forming operation was started. It is determined whether or not it has been done (step S6). If the predetermined time has not elapsed (NO in step S6), the controller 7 repeats the process of determining whether the arrival of the sheet 9 is detected by the sensor 43 until the predetermined time elapses (step S5).

If the arrival of the sheet 9 is detected by the sensor 43 before the predetermined time elapses (YES in step S5), the controller 7 continues execution of the print job (step S7). That is, the controller 7 temporarily stops the timing roller 32 at the timing when the arrival of the sheet 9 is detected by the sensor 43, and then drives the timing roller 32 again at predetermined rimming, thereby forming an image in the image forming section 3. The sheet 9 is fed to the position of the secondary transfer roller 25 in synchronization with the timing at which the toner image is conveyed to the position of the secondary transfer roller 25 .

After that, the controller 7 determines whether or not execution of the print job is finished (step S8). For example, the controller 7 determines that execution of the print job is finished when the conveying process for the number of sheets specified in the print job is finished. In this case (YES in step S8), the processing by the controller 7 ends. On the other hand, if the conveying process for the number of sheets specified in the print job has not been completed, the controller 7 determines that the execution of the print job has not yet been completed. In this case (NO in step S8), the processing by the controller 7 returns to step S1.

On the other hand, if the sensor 43 does not detect the arrival of the sheet 9 and the predetermined time has passed (YES in step S6), the controller 7 executes retry processing (step S9). In this retry process, the toner image formed so far in the image forming section 3 is temporarily discarded, and the process for transferring the toner image to the sheet 9 being conveyed is performed again.

FIG. 11 is a flowchart showing an example of a detailed processing procedure of the retry processing (step S9). When starting the retry process, the controller 7 stops driving the motor 18 of the registration unit 15 (step S10). At this time, the controller 7 also stops driving other rollers provided in the conveying section 2 . That is, the controller 7 immediately stops the conveying operation of the sheet 9 when the arrival of the sheet 9 is not detected by the sensor 43 before the predetermined time elapses.

After stopping the conveyance of the sheet 9, the controller 7 instructs the image forming section 3 to perform a cleaning operation (step S11). As a result, the image forming section 3 starts a cleaning operation of collecting the toner images held on the photosensitive drums and the intermediate transfer belt 24 and discharging them into the waste toner box 70 . At this time, since the motor 18 of the resist section 15 is stopped, the cleaning operation is performed while the stirring screw 73 is stopped.

The controller 7 waits until the cleaning operation in the image forming section 3 is completed (NO in step S12). After the cleaning operation is finished, the controller 7 restarts the conveying operation of the sheet 9 (step S13). At this time, the controller 7 also restarts the driving of the motor 18 of the registration section 15 . The controller 7 also drives the image forming section 3 to restart the toner image forming operation (step S14). As a result, the image forming section 3 re-forms the toner image discarded by the cleaning operation. The controller 7 starts a time measuring operation when restarting the toner image forming operation (step S15).

After starting the time measurement, the controller 7 determines whether or not the arrival of the sheet 9 is detected by the sensor 43 (step S16). If the arrival of the sheet 9 is not detected by the sensor 43 (NO in step S16), the controller 7 refers to the time when the measurement was started in step S15, and a predetermined time has passed since the toner image forming operation was resumed. It is determined whether or not it has been done (step S17). The predetermined time in this case is the same time as the predetermined time determined in step S6. As a result, if the predetermined time has not elapsed (NO in step S17), the controller 7 determines whether or not the arrival of the sheet 9 is detected by the sensor 43 until the predetermined time has elapsed. Repeat (step S16).

If the arrival of the sheet 9 is detected by the sensor 43 before the predetermined time elapses (YES in step S16), the controller 7 continues execution of the print job (step S18). That is, the controller 7 temporarily stops the timing roller 32 at the timing when the arrival of the sheet 9 is detected by the sensor 43, and then drives the timing roller 32 again at predetermined rimming, thereby forming an image in the image forming section 3. The sheet 9 is fed to the position of the secondary transfer roller 25 in synchronization with the timing at which the toner image is conveyed to the position of the secondary transfer roller 25 .

After that, the controller 7 determines whether or not execution of the print job is finished (step S19) in the same manner as in step S8 described above. terminate. On the other hand, if the print job is not finished (NO in step S19), the controller 7 finishes the retry process and returns the subsequent process to step S1 in FIG. Thereby, the processing for the succeeding sheet 9 is continued.

On the other hand, if the predetermined time has elapsed without the sensor 43 detecting the arrival of the sheet 9 (YES in step S17), the controller 7 determines that a jam has occurred due to the sheet 9 not detected by the sensor 43. . In this case, the controller 7 stops execution of the print job (step S20), and executes warning processing to warn the user that a jam has occurred (step S21). The retry processing is completed as described above.

As described above, the image forming apparatus 1 of the present embodiment is configured such that the sensor 43 detects that the sheet 9 has been conveyed to a predetermined position on the downstream side of the registration section 15 . If the sensor 43 does not detect the arrival of the sheet 9 within a predetermined period of time from the start of , the motor 18 is stopped. Then, the image forming apparatus 1 causes the image forming section 3 to perform the cleaning operation while the motor 18 is stopped, and after the cleaning operation is completed, the conveying section 2 and the image forming section 3 are driven again to execute the print job. to be able to continue According to such an image forming apparatus 1, since the sheet 9 is not conveyed during the cleaning operation, the occurrence of buckling or jamming of the sheet 9 can be suppressed.

(Second embodiment)
Next, a second embodiment of the invention will be described. In the above-described first embodiment, the motor 18 is always stopped when the sensor 43 does not detect the arrival of the sheet 9 within a predetermined period of time after the start of the toner image forming operation in the image forming section 3 . A cleaning operation is performed by the image forming section 3 in this state. However, when the toner amount of the toner image held on the photosensitive drum and the intermediate transfer belt is larger than a predetermined amount at the start of the cleaning operation, if the cleaning operation is performed without operating the stirring screw 73, the toner disposal port In the vicinity of 71 and 72, clogging with waste toner may occur, making it impossible to normally complete the cleaning operation. Further, when the amount of waste toner accumulated in the waste toner box 70 is larger than the predetermined amount at the start of the cleaning operation, if the cleaning operation is performed without operating the stirring screw 73, the toner disposal port 71 , 72 may be clogged with waste toner, and the cleaning operation may not be completed normally. Therefore, in this embodiment, if the sensor 43 does not detect the arrival of the sheet 9 within a predetermined time after the start of the toner image forming operation in the image forming unit 3, the cleaning operation is normally terminated. An example of performing the cleaning operation with the motor 18 stopped when it is determined that the cleaning operation can be normally completed will be described. The detailed configuration of the image forming apparatus 1 in this embodiment is the same as that described in the first embodiment.

The image forming apparatus 1 of this embodiment differs from the first embodiment in the detailed processing procedure of the retry process (step S9 in FIG. 10). Therefore, the retry processing of this embodiment will be described below.

FIG. 12 is a flowchart showing an example of a detailed processing procedure of retry processing (step S9 in FIG. 10) in the second embodiment. When starting the retry process, the controller 7 first determines whether the toner image held in the image forming section 3 is in a predetermined state (step S30). Here, the predetermined state means, for example, a state in which the toner amount of the toner image is equal to or less than a predetermined amount. Further, the predetermined amount is a toner amount that does not cause clogging of waste toner in the vicinity of the toner disposal openings 71 and 72 even if the cleaning operation is performed without operating the stirring screw 73. For example, the image forming apparatus 1 is the amount of toner set in advance to .

The controller 7 determines whether a predetermined state is established based on the toner amount of the toner image held on the photosensitive drum of each image forming unit 21 and the toner amount of the toner image held on the intermediate transfer belt 24. to judge whether At this time, the controller 7 calculates the toner amount on the photoreceptor drum based on the number of toner images held on the photoreceptor drum and the coverage (toner density ratio) of each toner image. Similarly, the controller 7 calculates the toner amount on the intermediate transfer belt 24 based on the number of toner images held on the intermediate transfer belt 24 and the coverage of each toner image. The controller 7 totals the amount of toner held on the photoreceptor drum and the intermediate transfer belt 24, and determines whether or not the total amount is equal to or less than a predetermined amount, thereby determining whether or not the toner is in a predetermined state. to judge. It should be noted that the controller 7 determines whether or not the toner is in a predetermined state based on either the amount of toner held on the photosensitive drum or the amount of toner held on the intermediate transfer belt 24 . It doesn't matter if it does.

If the toner image held in the image forming section 3 is in a predetermined state (YES in step S30), the controller 7 next determines whether the amount of waste toner accumulated in the waste toner box 70 is equal to or less than a predetermined amount. It is determined whether or not (step S31). In this case, the predetermined amount is an amount of waste toner that does not cause clogging of waste toner in the vicinity of the toner waste ports 71 and 72 even if the cleaning operation is performed without operating the stirring screw 73. For example, image formation is performed. This is the amount of waste toner preset in the apparatus 1 . The controller 7 manages the cumulative value of the amount of waste toner discharged to the waste toner box 70 by the cleaning operation so far, and compares the cumulative value with a predetermined amount to determine the amount of waste toner accumulated in the waste toner box 70. It is determined whether or not the amount of waste toner present is equal to or less than a predetermined amount.

As a result, if the amount of waste toner accumulated in the waste toner box 70 is equal to or less than the predetermined amount (YES in step S31), the controller 7 executes the processes from step S32 onward. The processing of steps S32 to S43 in FIG. 12 is the same as the processing of steps S10 to S21 shown in FIG. Therefore, the controller 7 causes the image forming section 3 to perform the cleaning operation while the driving of the motor 18 is stopped. Processing to continue is executed (steps S32 to S41). Further, if the arrival of the sheet 9 is not detected by the sensor 43 within a predetermined period of time after the conveying section 2 and the image forming section 3 are driven again, the controller 7 determines that a jam has occurred. Then, warning processing is performed (steps S42 and S43).

On the other hand, if the toner image held in the image forming section 3 is not in a predetermined state (NO in step S30), or if the amount of waste toner accumulated in the waste toner box 70 exceeds a predetermined amount (NO in step S31), the cleaning operation cannot be performed while the stirring screw 73 is stopped. Therefore, the controller 7 stops execution of the print job (step S42), and executes warning processing to warn the user that a jam has occurred (step S43). With this, the retry processing of the present embodiment ends.

In the above description, it is determined whether or not the toner image held in the image forming section 3 is in a predetermined state, and whether or not the amount of waste toner accumulated in the waste toner box 70 is equal to or less than a predetermined amount. Although the case where two judgments are made is exemplified, the present invention is not limited to this. That is, it may be determined whether or not to perform the cleaning operation while the motor 18 is stopped by determining only one of the above two determinations.

As described above, in the image forming apparatus 1 of the present embodiment, if the sensor 43 does not detect arrival of the sheet 9 within a predetermined time after the start of the toner image forming operation in the image forming section 3, the motor It is determined whether the cleaning operation can be performed normally with the motor 18 stopped, and based on the determination result, the cleaning operation is performed with the motor 18 stopped. Therefore, the vicinity of the toner disposal openings 71 and 72 is not clogged with waste toner during the cleaning operation, and the cleaning operation can be normally completed.

Note that the present embodiment is the same as that described in the first embodiment except for the points described above.

(Third embodiment)
Next, a third embodiment of the invention will be described. In the second embodiment described above, when it is determined that the cleaning operation cannot be performed normally with the motor 18 stopped, execution of the print job is stopped. On the other hand, in this embodiment, when it is determined that the cleaning operation cannot be performed normally with the motor 18 stopped, a normal cleaning operation is performed with the motor 18 in operation. The detailed configuration of the image forming apparatus 1 in this embodiment is the same as that described in the first embodiment.

The image forming apparatus 1 of this embodiment differs from each of the first and second embodiments in the detailed processing procedure of the retry process (step S9 in FIG. 10). Therefore, the retry processing of this embodiment will be described below.

13 and 14 are flowcharts showing an example of detailed processing procedures of retry processing (step S9 in FIG. 10) in the third embodiment. The retry process shown in FIG. 13 differs from the retry process shown in FIG. 12 in the normal cleaning process (step S44). After starting the retry process, the controller 7 determines whether or not the cleaning operation can be performed normally with the motor 18 stopped (steps S30 and S31), as in the second embodiment. As a result, when it is determined that the cleaning operation cannot be performed normally with the motor 18 stopped (NO in steps S30 and S31), the controller 7 executes normal cleaning processing (step S44). This normal cleaning process is a cleaning process performed in a state where the stirring screw 73 is operated by driving the motor 18 .

FIG. 14 is a flowchart showing an example of detailed processing procedures of the normal cleaning process (step S44). After starting the normal cleaning process, the controller 7 instructs the image forming section 3 to perform the cleaning operation without stopping the motor 18 (step S50). As a result, the image forming section 3 starts a cleaning operation of collecting the toner images held on the photosensitive drums and the intermediate transfer belt 24 and discharging them into the waste toner box 70 . At this time, since the driving of the motor 18 of the registration section 15 is continued, the stirring screw 73 continues to operate. Therefore, it is possible to prevent clogging of waste toner in the vicinity of the toner waste ports 71 and 72 during the cleaning operation.

After starting the cleaning operation, the controller 7 determines whether or not the cleaning operation has ended (step S51). is detected (step S52). If arrival of the sheet 9 has not been detected (NO in step S52), the process returns to step S51 to repeat determination as to whether or not the cleaning operation has ended.

If the sensor 43 does not detect the arrival of the sheet 9 and the cleaning operation ends (YES in step S51), the controller 7 resumes execution of the print job (step S53). That is, the controller 7 drives the conveying section 2 to restart the conveyance of the sheet 9, and drives the image forming section 3 to restart the toner image forming operation. After that, the controller 7 determines whether or not the execution of the print job is finished (step S54) in the same manner as in step S8 described above. terminate. On the other hand, if the print job is not completed (NO in step S54), the controller 7 terminates the normal cleaning process and the retry process, and returns the subsequent process to step S1 in FIG. Thereby, the processing for the succeeding sheet 9 is continued.

On the other hand, if the arrival of the sheet 9 is detected by the sensor 43 before the cleaning operation ends (YES in step S52), if the cleaning operation is continued while the motor 18 is driven, the sheet 9 will be removed. The sheet is transported to the downstream side of the registration section 15 . To prevent this, the controller 7 forcibly terminates the cleaning operation and stops driving the motor 18 (step S55). Then, the controller 7 stops execution of the print job (step S56), and executes warning processing to warn the user that a jam has occurred (step S57). With this, the normal cleaning process is completed.

In such a normal cleaning process, the cleaning operation is performed while the motor 18 is being driven, and when the cleaning operation is finished, execution of the print job can be continued. Therefore, compared to the second embodiment, there is an advantage that the frequency of print job stoppages can be reduced.

As described above, in the image forming apparatus 1 of the present embodiment, if the toner image held in the image forming unit 3 is in a predetermined state when the sheet is not detected by the sensor 43 before the predetermined time elapses, , the motor 18 is stopped to cause the image forming section 3 to perform a cleaning operation of collecting the toner image and leading it to the waste toner box 70 . Further, when the toner image held in the image forming section 3 is not in a predetermined state, the image forming section 3 is caused to perform a cleaning operation while the motor 18 is continuously operated. By switching the cleaning operation in this manner, the frequency at which the execution of the print job can be continued increases.

Note that the present embodiment is the same as that described in the first embodiment or the second embodiment except for the points described above.

(Modification)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the contents described in the above embodiment, and various modifications are applicable.

For example, in the above embodiment, the image forming apparatus 1 is a printer having only a print function. However, image forming apparatuses to which the present invention can be applied are not limited to printers having only a print function. For example, the image forming apparatus 1 may be an MFP (Multifunction Peripherals) or a facsimile machine. Further, in the above embodiment, the image forming apparatus 1 capable of performing color output was exemplified, but the image forming apparatus 1 may be an apparatus capable of performing only monochrome output.

Further, in the above embodiment, an example in which the sensor 43 is configured by an optical sensor including a light projecting portion and a light receiving portion has been described. However, the sensor 43 that detects the attitude of the gate member 35 is not necessarily limited to the optical sensor.

Further, the sensor 43 in the above embodiment can detect that the leading edge of the sheet 9 has reached a predetermined position on the downstream side of the registration section 15 by detecting that the gate member 35 has been displaced to the second posture. there is However, the arrangement mode of the sensor 43 is not limited to that described in the above embodiment. For example, as shown in FIG. 15, the sensor 43 may be arranged so as to directly detect the sheet 9 conveyed along the conveying path downstream of the registration section 15 .

Furthermore, in the above embodiment, the case where the program 52 executed by the CPU 50 of the controller 7 is stored in advance in the memory 51 is exemplified. However, the program 52 may be installed in the image forming apparatus 1 via, for example, a communication interface. In this case, the program 52 is provided in a form that can be downloaded via the Internet or the like. Moreover, the program 52 is not limited to this, and may be provided in a form recorded in a computer-readable recording medium such as a CD-ROM or a USB memory.

1 image forming apparatus 3 image forming section (image forming means)
7 controller (control means)
9 sheet 11 paper feeding unit (paper feeding means)
12 Conveyance Path 15 Registration Section (Registration Means)
18 motor (driving means)
32, 34 timing roller 35 (35a, 35b) gate member 36 sheet locking portion 43 sensor (detection means)
70 waste toner box (waste toner accumulation means)
73 stirring screw (stirring means)

Claims (19)

registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
a control means for controlling the driving means;
with
When the sheet is not detected by the detecting means within a predetermined time after the image forming means starts forming a toner image, the control means stops the driving means and operates the stirring means. An image forming apparatus, wherein the image forming device is caused to perform a cleaning operation in which the toner image is collected and transferred to the waste toner storage device in a non-operating state. The control means controls the drive means when the sheet is not detected by the detection means before the predetermined time elapses, and when the toner amount of the toner image held in the image forming means is equal to or less than a predetermined amount. 2. The image forming apparatus according to claim 1 , wherein the cleaning operation is performed by stopping the cleaning operation . The image forming means has a photosensitive drum for forming a toner image on its surface,
3. The image forming apparatus according to claim 2 , wherein said control means determines whether or not the toner amount of the toner image held on said photosensitive drum is equal to or less than a predetermined amount . The image forming means has an intermediate transfer belt that conveys the toner image to the predetermined position,
3. The image forming apparatus according to claim 2 , wherein said control means determines whether or not the toner amount of the toner image held on said intermediate transfer belt is equal to or less than a predetermined amount . The image forming means has a photosensitive drum for forming a toner image on its surface, and an intermediate transfer belt for conveying the toner image transferred from the photosensitive drum to the predetermined position,
3. The apparatus according to claim 2 , wherein said control means determines whether or not the toner amount of the toner image held on both said photosensitive drum and said intermediate transfer belt is equal to or less than a predetermined amount. Image forming device. 6. The image forming apparatus according to claim 2 , wherein said control means detects the amount of toner based on the number of toner images held in said image forming means. 7. The image forming apparatus according to claim 2 , wherein said control means detects the amount of toner based on the coverage of the toner image held in said image forming means. The control means controls the drive means when the sheet is not detected by the detection means before the predetermined time elapses, and when the amount of waste toner accumulated in the waste toner accumulation means is equal to or less than a predetermined amount. 8. The image forming apparatus according to any one of claims 1 to 7 , wherein the image forming apparatus is stopped and the cleaning operation is performed . 9. The image forming apparatus according to claim 1 , wherein said control means operates said driving means after said cleaning operation in said image forming means is completed. 10. The image forming apparatus according to claim 9 , wherein said control means causes said image forming means to resume a toner image forming operation after said cleaning operation in said image forming means is completed. The control means stops the driving means again when the sheet is not detected by the detecting means within the predetermined time after the toner image forming operation is restarted in the image forming means. 11. The image forming apparatus according to claim 10 . The control means continuously operates the drive means when the sheet is detected by the detection means before the predetermined time elapses after the toner image forming operation is restarted in the image forming means. The image forming apparatus according to claim 10 or 11 , characterized by: registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
a control means for controlling the driving means;
with
When the sheet is not detected by the detecting means within a predetermined period of time after the start of toner image formation in the image forming means , the control means controls the toner image held in the image forming means. is less than a predetermined amount, the driving means is stopped to cause the image forming means to collect the toner image and perform a cleaning operation to lead it to the waste toner accumulating means. 2. An image forming apparatus, wherein, when the toner amount of the toner image formed is not equal to or less than the predetermined amount, the driving means is continuously operated to cause the image forming means to perform the cleaning operation. When the sheet is detected by the detecting means while the image forming means is caused to perform the cleaning operation by continuously operating the driving means, the control means stops the driving means. 14. The image forming apparatus according to claim 13 . When the cleaning operation ends without the sheet being detected by the detecting unit while the driving unit is continuously operated to cause the image forming unit to perform the cleaning operation, 15. An image forming apparatus according to claim 13 , wherein said image forming means is caused to resume a toner image forming operation. registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
A control method for an image forming apparatus comprising
a first step of operating the driving means and causing the image forming means to start a toner image forming operation;
a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started in the first step;
If it is determined in the second step that the sheet has not been detected before the predetermined time elapses, the driving means is stopped and the toner image is collected by the image forming means while the stirring means is not operated. a third step of performing a cleaning operation leading to the waste toner storage means ;
A control method characterized by having registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
A control method for an image forming apparatus comprising
a first step of operating the driving means and causing the image forming means to start a toner image forming operation;
a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started in the first step;
When it is determined in the second step that the sheet has not been detected before the predetermined time elapses and the toner amount of the toner image held in the image forming means is equal to or less than the predetermined amount, the driving means is stopped to cause the image forming means to collect the toner image and perform a cleaning operation leading to the waste toner accumulation means, and when the toner amount of the toner image held in the image forming means is not equal to or less than the predetermined amount, is a third step of continuously operating the driving means to cause the image forming means to perform the cleaning operation ;
A control method characterized by having registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
A program executed in an image forming apparatus comprising:
a first step of operating the driving means and causing the image forming means to start a toner image forming operation;
a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started in the first step;
If it is determined in the second step that the sheet has not been detected before the predetermined time elapses, the driving means is stopped and the toner image is collected by the image forming means while the stirring means is not operated. a third step of performing a cleaning operation leading to the waste toner storage means ;
A program characterized by causing the execution of registration means for performing sheet skew correction and conveying the sheet downstream;
detection means for detecting the sheet conveyed to the downstream side of the registration means by the registration means after skew correction of the sheet is performed;
image forming means for forming and holding a toner image and transferring the toner image when the sheet conveyed downstream by the resist means passes a predetermined position;
waste toner accumulating means for collecting and accumulating waste toner remaining in the image forming means;
a stirring means for stirring the waste toner accumulated in the waste toner accumulation means;
driving means for driving the resist means and the stirring means in conjunction with each other;
A program executed in an image forming apparatus comprising:
a first step of operating the driving means and causing the image forming means to start a toner image forming operation;
a second step of determining whether or not the sheet is detected by the detecting means within a predetermined time after the toner image forming operation in the image forming means is started in the first step;
When it is determined in the second step that the sheet has not been detected before the predetermined time elapses and the toner amount of the toner image held in the image forming means is equal to or less than the predetermined amount, the driving means is stopped to cause the image forming means to collect the toner image and perform a cleaning operation leading to the waste toner accumulation means, and when the toner amount of the toner image held in the image forming means is not equal to or less than the predetermined amount, is a third step of continuously operating the driving means to cause the image forming means to perform the cleaning operation ;
A program characterized by causing the execution of

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