The present disclosure relates to a technique of providing information for removal of a recording material which is stuck inside an image forming apparatus, such as a copier or a printer, and a feeding apparatus employed in the image forming apparatus.
In general, in an image forming apparatus, such as a copier or a printer, a recording material may be stuck in the apparatus during a feeding operation. If such feeding failure (hereinafter referred to as sheet jam) occurs, a recording material which causes the sheet jam (hereinafter referred to as a jam sheet) is to be removed from the inside of the apparatus.
Japanese Patent Laid-Open No. 2004-280076 discloses an image forming apparatus including a feeding roller which feeds a recording material from a cassette to a conveying path and a sensor which detects the recording material and which is disposed on the conveying path. If the sensor does not detect a recording material for a predetermined period of time after an operation of feeding a recording material is started using the feeding roller, it is determined that delay jam has occurred. The image forming apparatus according to Japanese Patent Laid-Open No. 2004-280076 has a door which opens the conveying path. When opening the door, a user may remove a jam sheet which is stuck inside the apparatus.
In Japanese Patent Laid-Open No. 2004-280076, a determination as to whether the jam sheet is stopped in a state in which the jam sheet extends across the cassette and the conveying path or a state in which a jam sheet is accommodated in the cassette is not made when the delay jam occurs. Accordingly, when the jam sheet is stopped in the state in which the jam sheet is accommodated in the cassette, the user may not visually recognize the jam sheet only by opening the door, and therefore, the cassette is required to be opened and this is burdensome for the user.
The present disclosure provides a feeding apparatus that reduces burden of a user while clearing a jam.
A feeding apparatus according to the present disclosure includes a feeding rotary member configured to feed a recording material accommodated in an accommodation unit and a conveying rotary member pair configured to convey the recording material fed by the feeding rotary member. The conveying rotary member pair includes first and second rotary members which form a nip portion and the recording material is conveyed while being nipped in the nip portion. The feeding apparatus further includes an output unit configured to output a state signal in accordance with a rotation state of the second rotary member, a detection unit configured to determine whether the recording material has reached a position on a downstream side relative to the nip portion in a feeding direction of the recording material, and a control unit configured to stop the feeding operation in a case where the detection unit does not detect the recording material by the time when a threshold time has elapsed after the feeding operation is started on the recording material by the feeding rotary member and the conveying rotary member pair. The control unit determines that the recording material is stopped at a position on an upstream side relative to the nip portion in the feeding direction in a case where a rotation speed of the second rotary member, indicated by the state signal output from the output unit at least in a period of time from when a period of time required for the recording material to reach the nip portion has elapsed to when the feeding operation is stopped, is faster than a threshold speed.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
In a first embodiment, a laser beam printer 101 (hereinafter referred to as a printer 101) employing an electrophotographic printing method will be described as an image forming apparatus.
A cassette 102 is an accommodation unit which accommodates sheets S (recording materials) and is detachable from a body of the printer 101. A rear-end regulating plate 126 disposed in the cassette 102 regulates rear ends (ends on an upstream side in a feeding direction) of the sheets S accommodated in the cassette 102. The rear-end regulating plate 126 is movable in the feeding direction and is disposed in a regular position corresponding to a size (a length in the feeding direction) of the sheets S so that the sheets S are set in an appropriate position.
A pickup roller 103 (a feeding rotary member, and hereinafter referred to as a pick-roller 103) feeds (conveys) the sheets S accommodated in the cassette 102 in a state in which the cassette 102 is attached to the body of the printer 101. Each of the sheets S which is fed by the pick-roller 103 is supplied to a downstream side by a feed roller 106 (a conveying rotary member) and reaches a top sensor 108 through a pair of registration rollers 107 (hereinafter referred to as a registration-roller pair 107). A separation roller 105 (a separation rotary member) forms a separation nip portion with the feed roller 106 so as to prevent a plurality (two or more) of the sheets S are supplied to the downstream side relative to the separation nip portion. Operation of the separation roller 105 will be described in detail hereinafter. By this, only one of the sheets S accommodated in the cassette 102 which is positioned in an uppermost portion in a vertical direction is fed to the registration-roller pair 107. The conveying rotary member and the separation rotary member are collectively referred to as a conveying rotary member pair.
The sheet S detected by the top sensor 108 (a detection unit) is in turn conveyed to an image forming unit. The image forming unit includes a photosensitive drum 109, a charge roller 111, a laser scanner 113, a developing device 112, a transfer roller 110, and a fixing device 114. The photosensitive drum 109 is uniformly charged by the charge roller 111 and is irradiated with laser light L by the laser scanner 113 so that an electrostatic latent image is formed on a surface of the photosensitive drum 109. The electrostatic latent image formed as described above is visualized as a tonner image when toner is supplied from the developing device 112. The photosensitive drum 109 and the transfer roller 110 form a transfer nip portion, and the sheet S is conveyed to the transfer nip portion in synchronization with rotation of the photosensitive drum 109. The toner image formed on the photosensitive drum 109 is transferred on the sheet S in the transfer nip portion. A voltage having polarity which is opposite to that of the toner image is applied to the transfer roller 110 so that the toner image is transferred. The sheet S on which the toner image has been transferred is conveyed to the fixing device 114 which heats and presses the sheet S. As a result, the toner image transferred to the sheet S is fixed on the sheet S. The sheet S to which the toner image is fixed is conveyed by triple rollers 116, intermediate discharge rollers 117, and discharge rollers 118 and is discharged to a discharge tray 121. The series of printing operations is thus terminated.
Furthermore, in a case where double-sided printing is performed on the sheet S, the sheet S is not discharged to the discharge tray 121 after single-side printing is performed on the sheet S, and the triple rollers 116, the intermediate discharge rollers 117, and the discharge rollers 118 are reversely rotated after a rear end of the sheet S has passed the triple rollers 116. The sheet S is conveyed to a double-sided conveying path 125 and further conveyed by double-sided conveying rollers 122 to the image forming unit again. In this way, the double-sided printing is performed on the sheet S.
Furthermore, in
An encoder 203 (an output unit) which detects a rotation speed (the number of rotations per unit time) of the separation roller 105 is connected to the engine controller 201. As the encoder 203, a code wheel which is coaxially disposed with the separation roller 105 and which rotates with the separation roller 105 may be used. The printer 101 includes a photosensor including a light emission unit and a light reception unit and outputs a pulse signal by reading a plurality of slits formed on the code wheel. The photosensor outputs an ON signal when the light reception unit receives light which is emitted from the light emission unit and which passes the slits and outputs an OFF signal when the light reception unit does not receive any light so as to output a pulse signal. The engine controller 201 may detect the rotation speed of the separation roller 105 in accordance with an output interval (period) of the pulse signal. Furthermore, a magnetic rotary encoder, a photo-interrupter, or the like, may be employed depending on required accuracy or a disposed position.
The engine controller 201 includes a measurement unit 206, a determination unit 207, an output unit 208, a storage unit 209, and a driving controller 210. The measurement unit 206 measures a period of time from when the pick-roller 103 starts feeding of the sheet S to when the top sensor 108 detects the sheet S. Furthermore, the measurement unit 206 measures a rotation speed of the separation roller 105 using the encoder 203. The determination unit 207 determines whether sheet feeding failure (jam) of the sheet S has occurred based on the period of time measured by the measurement unit 206. When the sheet feeding failure has occurred, the determination unit 207 determines a position of the sheet S which is stuck inside the apparatus body based on the rotation speed of the separation roller 105 measured by the measurement unit 206. Then the determination unit 207 selects one of the cassette 102 and the door 127 as an access position for removing the stuck sheet S to an outside of the apparatus body. The output unit 208 outputs information (an image or a message) indicating the access position selected by the determination unit 207 to the panel 211. The storage unit 209 stores information on a request of printing transmitted from the video controller 202 and the rotation speed of the separation roller 105 measured by the measurement unit 206. The driving controller 210 performs switching of driving states of the pick-roller 103, the feed roller 106, the separation roller 105, and the registration-roller pair 107 in accordance with results of detections of the sensors so as to control activation and stop of a sheet feeding mechanism.
Next, sheet feeding control performed by the printer 101 of this embodiment will be described with reference to
The driving force is transmitted to the separation roller 105 in the direction in which feeding of the sheets S is prevented (a counterclockwise direction in
Next, a case where sheet feeding failure occurs before one of the sheets S reaches the top sensor 108 will be described with reference to
If the cassette 102 is opened in the state of
A graph in
At a timing To1 in the graph of
On the other hand,
A graph in
Accordingly, if the sheet feeding failure has occurred before the sheet S1 reaches the top sensor 108, a stop position of the sheet S1 which causes the sheet jam may be specified by the rotation speed of the separation roller 105 in the period from the timing To1 to the timing To2 (a detection period). Specifically, if the rotation speed of the separation roller 105 in the period from the timing To1 to the timing To2 is equal to or lower than a threshold speed Vt, the determination unit 207 may determine that the sheet jam illustrated in
If the stop position of the sheet S1 may be determined in this way, the determination unit 207 may select an access position for extracting the stuck sheet S1 out of the apparatus body. Then if the output unit 208 transmits a notification indicating the selected access position through the panel 211, usability may be improved.
However, even if the rotation speed of the separation roller 105 in the period from the timing Tot to the timing To2 is equal to or smaller than the threshold speed Vt, the sheet jam illustrated in
As described above, when two or more sheets are conveyed to the separation nip portion due to friction between the sheets, the separation roller 105 is stopped or starts rotation in the direction in which the sheet feeding is prevented. Therefore, in a case where the sheet S1 which is positioned on the uppermost portion may not be fed since the pick-roller 103 slips in the state in which the two or more sheets (sheets S2 and S3) are extracted to the separation nip portion due to the friction, a rotation speed of the separation roller 105 is equal to or lower than the threshold speed Vt. However, the sheet S1 stopped due to the sheet jam is accommodated in the cassette 102 and the sheet jam illustrated in
Therefore, in a case where a rotation speed of the separation roller 105 in the period from the timing To1 to the timing To2 is equal to or lower than the threshold speed Vt, it is difficult to uniquely specify a stop position of the sheet S1 which causes the sheet jam, and therefore, an access position is not selected in this embodiment.
Furthermore, when the sheet jam illustrated in
If the trailing end of the sheet S1 passes the separation nip portion, the sheet S1 which causes the sheet lam is positioned on the downstream side in the sheet feeding direction relative to the separation nip portion and on the upstream side in the sheet feeding direction relative to the top sensor 108, and therefore, the sheet S1 is preferably extracted by opening the door 127. However, in this case, the trailing end of the sheet S1 has passed the separation nip portion, and therefore, the separation roller 105 is driven to be rotated in accordance with the feed roller 106 and the rotation speed thereof is not lowered. Therefore, depending on a timing when the trailing end of the sheet S1 passes the separation nip portion, the rotation speed of the separation roller 105 in the period from the timing Tot to the timing Tot becomes higher than the threshold speed Vt.
Consequently, although the output unit 208 transmits a notification which causes the user to extract the sheet S1 by opening the cassette 102 to the user, the notification corresponds to wrong detection since the sheet S1 which actually causes the sheet jam is positioned on the downstream side in the sheet feeding direction relative to the separation nip portion. Therefore, to prevent the wrong detection, if a length of the sheets S is shorter than a shortest length which is set in advance, selection of an access position is not performed in accordance with a rotation speed of the separation roller 105. Here, the shortest length is at least longer than the distance between the separation nip portion to the top sensor 108 on the conveying path. Specifically, the shortest length is obtained by adding a certain pushing margin length (10 mm, for example) to the distance between the separation nip portion and the top sensor 108 on the conveying path.
Furthermore, a friction coefficient on a sheet surface, a weight, and the like vary depending on a type (sheet type) of the sheets S, and therefore, increasing tendency of the conveyance resistance of the sheet S1 due to occurrence of sheet jam also varies depending on a type of the sheets S. Therefore, a period of time in which the trailing end of the sheet S1 is continuously conveyed for a certain period of time while the leading end of the sheet S1 is bent in the jam occurrence position varies depending on a sheet type. For example, in a case of a thin sheet, stiffness is weak, and therefore, the sheet S1 is continuously pushed until the sheet feeding operation is stopped at the timing To2. As a result, even in a case where the sheet jam illustrated in
A method for determining an access position at the time of jam clearance according to this embodiment will be described with reference to flowcharts in
First, in
On the other hand, when the determination is negative in step S103, the engine controller 201 determines whether the sheet feeding time measured by the measurement unit 206 exceeds the threshold time T1 (S107). When the determination is negative, the engine controller 201 causes the driving controller 210 to continuously perform the sheet feeding operation. When the determination is affirmative, the storage unit 209 stores the rotation speed of the separation roller 105 measured by the measurement unit 206 (S108). Thereafter, the engine controller 201 determines whether the sheet feeding time measured by the measurement unit 206 exceeds a threshold time T2 in step S109. When the determination is negative, the engine controller 201 causes the driving controller 210 to continuously perform the sheet feeding operation. When the determination is affirmative, the determination unit 207 determines that the sheet feeding failure has occurred (S110) and determines an access position for extracting the sheet S1 based on the rotation speed of the separation roller 105 stored in the storage unit 209 (S111). A subroutine in step S111 will be described below in detail. Thereafter, the measurement unit 206 terminates the measurement of the rotation speed of the separation roller 105 (S112).
The subroutine in step S111 will now be described with reference to
On the other hand, when it is determined that the actual length of the sheet S is shorter than the shortest length of the sheet S in step S201, the output unit 208 prompts, through the panel 211, the user to remove the jam sheet by accessing the cassette 102 or the door 127 (S205). The control for determination of an access position is thus terminated.
As described above, according to this embodiment, it is determined whether the cassette 102 is to be accessed by the user so that the jam sheet is removed based on the rotation speed of the separation roller 105. Accordingly, an image forming apparatus and a feeding apparatus which may reduce a burden of users when jam clearance is performed may be provided.
A second embodiment will now be described. Descriptions of main portions are the same as those of the first embodiment, and therefore, only portions different from the first embodiment will be described hereinafter.
First, a method for specifying a sheet position at a time of sheet feeding failure according to this embodiment will be described. In the first embodiment, when the sheet feeding failure occurs before the sheet S1 reaches the top sensor 108, a position of the sheet S1 which stops and causes sheet jam is specified in accordance with a rotation speed of the separation roller 105 obtained in the period from the timing Tot to the timing To2. Here, in the printer 101, if a distance from the separation nip portion to the top sensor 108 on the conveying path is short or if a sheet feeding speed of the sheet S is set high, the threshold time T2 for determining the sheet feeding failure may be set to be short. In this case, the period from the timing Tot to the timing To2 for measuring rotation speed data of the separation roller 105 is short, and therefore, the printer 101 is sensitively affected by an outlier and an abnormal value, and accordingly, misjudgment may be made. In this embodiment, an appropriate determination is made even in this case.
A method for determining an access position at a time of jam clearance according to this embodiment will be described with reference to a flowchart of
First, in
On the other hand, when the determination is negative in step S302, the engine controller 201 determines whether the sheet feeding time measured by the measurement unit 206 exceeds a threshold time T2 (S305). When the determination is negative, the engine controller 201 causes the driving controller 210 to continuously perform the sheet feeding operation. When the determination is affirmative, the determination unit 207 determines that the sheet feeding failure has occurred (S306). The measurement unit 206 starts measurement of the rotation speed of the separation roller 105 (S307), and the storage unit 209 stores the rotation speed of the separation roller 105 measured by the measurement unit 206 (S308). Thereafter, in step S309, the engine controller 201 determines whether a sheet feeding time after the sheet feeding failure is detected has exceeded a threshold time T3. When the determination is negative, the engine controller 201 causes the driving controller 210 to continuously perform the sheet feeding operation, causes the measurement unit 206 to continuously measure the rotation speed of the separation roller 105, and causes the storage unit 209 to continuously perform the storage. When the determination is affirmative, the determination unit 207 determines an access position for extracting the sheet S1 based on the rotation speed of the separation roller 105 stored in the storage unit 209 (S111). A subroutine in step S111 is the same as that of the first embodiment. The control for determination of an access position is thus terminated.
As described above, according to this embodiment, following effects may be attained in addition to the effects of the first embodiment. Specifically, even if a distance from a separation nip portion to the top sensor 108 on a conveying path is short or even if the sheet feeding speed of the sheets S is set high, misdetection for a determination of an access position is avoided and a position where the feeding failure has occurred may be accurately specified.
Note that, although the rotation speed of the separation roller 105 for a determination of an access position is an average value of data stored in the storage unit 209 according to the first and second embodiments, a center value, a largest value, or a smallest value of the data stored in the storage unit 209 may be employed.
Furthermore, although the output unit 208 displays the access position in the panel 211 according to the first and second embodiments described above, the present disclosure is not limited to this. For example, information on a selected access position may be transmitted to an external apparatus (an information processing apparatus, such as a PC) connected through a communication line so that the access point is displayed on a display of the external apparatus. Alternatively, light emitting diodes (LEDs) (light emitting units) may be individually disposed on the cassette 102 and the door 127 so that one of the LEDs corresponding to a selected access position may be emitted.
Although the sheets S are fed from the cassette 102 detachable from the body of the printer 101 according to the first and second embodiments described above, the present disclosure is not limited to this. The present disclosure is applicable to a configuration in which the sheets S are fed from a manual feed tray (not illustrated) which is not detachable from the body of the printer 101. Here, the manual feed tray indicates a mounting unit where the sheets S are mounted in a state in which the sheets S are exposed outside the body of the printer 101.
When the sheets S are fed from the manual feed tray, unlike the case of the cassette 102, a user may determine whether a jam sheet is stopped while striding the tray and the conveying path or a jam sheet is stopped while being accommodated in the tray without opening of the door 127. However, a case where the jam sheet which is stopped while being accommodated in the tray is not bent is difficult to be distinguished from a case where the sheets S are normally mounted on the tray. Therefore, the user may open the door 127 under a wrong impression that the jam sheet is positioned on the conveying path. According to this disclosure, such a burden of the user may be reduced.
Furthermore, according to the first and second embodiments described above, in the feeding operation described with reference to
Specifically, an ON state of the driving of the pick-roller 103 is maintained without performing switching to the OFF state before the trailing end of the sheet S1 passes the pick-roller 103. Then, after the trailing end of the sheet S1 has passed the pick-roller 103, the pick-roller 103 is in contact with a second sheet S2 following the sheet S1 and the sheet S2 is set as a preceding sheet to be fed. When a leading end of the sheet S2 reaches the separation nip portion in a state in which the sheet S1 is positioned in the separation nip portion, the separation roller 105 stops rotation or is rotated in the direction in which the sheet feeding is prevented as described above. When the change of the rotation state of the separation roller 105 is detected by the encoder 203 and the driving of the pick-roller 103 is switched to the OFF state, the leading end of the sheet S2 may be brought to the separation nip portion.
In the feeding operation described with reference to
According to the first and second embodiments described above, the control unit 200 is mounted on the printer 101. However, the present disclosure is not limited to this. An option controller 250 may be mounted on a sheet feeding option 151 which is detachable from a printer 101 as illustrated in
A cassette 152 is an accommodation unit which accommodates sheets S (recording materials) and is detachable from a body of the sheet feeding option 151. A rear-end regulating plate 176 disposed in the cassette 152 regulates rear ends (ends on an upstream side in a feeding direction) of the sheets S accommodated in the cassette 152. The rear-end regulating plate 176 is movable in the feeding direction and is disposed in a regular position corresponding to a size (a length in the feeding direction) of the sheets S so that the sheets S are set in an appropriate position.
A pickup roller 153 (hereinafter referred to as a pick-roller 153) feeds (conveys) the sheets S accommodated in the cassette 152 in a state in which the cassette 152 is attached to the body of the sheet feeding option 151. Each of the sheets S which is fed by the pick-roller 153 is supplied to a downstream side by a feed roller 156 and reaches a top sensor 108 through an option sensor 158 and a registration-roller pair 107. A separation roller 155 forms a separation nip portion with the feed roller 156 so as to prevent a plurality of the sheets from being supplied to the downstream side relative to the separation nip portion. Operation of the separation roller 155 is the same as that of the separation roller 105. By this, only one of the sheets S accommodated in the cassette 152 which is positioned in an uppermost portion in a vertical direction is fed to the registration-roller pair 107.
Furthermore, a sheet detection sensor 154 determines whether a sheet S is accommodated in the cassette 152. The sheet feeding option 151 includes an operation panel 261 (hereinafter referred to as a panel 261) which displays various information for a user. The sheet feeding option 151 further includes a door 157 which is openable relative to the apparatus body. The user may access a conveying path on the downstream side in the sheet feeding direction relative to the separation nip unit by opening the door 157. Note that a driving configuration of the sheet feeding option 151 is the same as that of the printer 101 illustrated in
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2017-053523 filed Mar. 17, 2017, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2017-053523 | Mar 2017 | JP | national |