JP6437027B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to sheet material feeding control.

  Conventionally, a stepping motor is often used as a drive source for a sheet material feeding / conveying system in an image forming apparatus. In addition, the stepping motor is small and can be configured at low cost. However, the stepping motor is likely to cause a so-called step-out phenomenon in which the rotation of the rotor cannot be synchronized with the input of the pulse signal due to an overload or a sudden change in rotational speed. If the rotor steps out in an accelerated state, it cannot synchronize with the pulse signal and stops the paper feeding / conveying operation. Therefore, a stepping motor having a large output torque may be selected in the image forming apparatus so that a step-out phenomenon does not occur even under various user usage conditions. As another countermeasure against the step-out phenomenon, for example, Patent Document 1 proposes a technique for controlling the driving current of the stepping motor in accordance with the size of the load. For example, Patent Document 2 proposes a technique for changing the control from detection of the rotor position of the stepping motor to increase the output efficiency of the stepping motor.

JP 2008-301625 A JP 2013-151340 A

  In order to reduce the cost of the paper feeding mechanism, there is an image forming apparatus that does not have a sensor function for detecting the presence or absence of a sheet material placed on a lifting plate. In such an image forming apparatus, when the sheet material is not placed, the feeding roller may be driven in a state where the elevating plate is directly biased to the feeding roller, and in this case, the driving source is used. The load on the stepping motor is maximized. If the stepping motor steps out in such a state, the state where the elevating plate is urged by the feeding roller is maintained, so that the normal state cannot be restored. Therefore, in this type of image forming apparatus, a stepping motor having a high output torque that does not step out even when the lifting plate is urged against the feeding roller is used. However, the use of an expensive stepping motor increases the cost. Yes.

  The present invention has been made under such circumstances, and an object of the present invention is to restore a normal state from a state in which an elevating plate is urged to a feeding roller in an apparatus using a low output stepping motor. To do.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) An elevating plate that can be moved up and down with a recording material mounted thereon, elevating means that elevates the elevating plate, and a recording material placed on the elevating plate raised by the elevating means and contacting and rotating A feeding means for feeding the abutted recording material, a driving source for driving the elevating means and the feeding means by rotation, and a control of the driving source so that the driving source rotates. Control means for setting and a setting means for setting the type of the recording material, and the control so that the drive source rotates at a first rotation speed corresponding to the type of the recording material set by the setting means. While the means controls the drive source, in a state where a recording material of a type different from the type of recording material set by the setting means is placed on the lifting plate, the feeding means is the lifting plate In contact with the recording material placed on the If the state where feeding means can not rotate occurs, the control means, the first said drive source at a slower second rotational speed than the rotational speed of the controls the driving source to rotate, the feeding means The image forming apparatus is characterized in that the drive source is stopped in a state where the drive source is separated from the recording material placed on the lifting plate .
(2) An elevating plate that can be moved up and down with a recording material mounted thereon, elevating means for elevating the elevating plate, and a recording material placed on the elevating plate raised by the elevating means and contacting and rotating To feed the abutted recording material, to detect the recording material fed by the feeding means, and to drive the elevating means and the feeding means by rotating. And a control unit that controls the drive source so that the drive source rotates, and a setting unit that sets the type of the recording material. The type of the recording material set by the setting unit While the control unit controls the drive source so that the drive source rotates at a corresponding first rotation speed, a recording material of a type different from the type of the recording material set by the setting unit moves up and down. In the state of being placed on the plate, When the means comes into contact with the recording material placed on the elevating plate and the feeding means cannot rotate, the control means has a second rotational speed that is slower than the first rotational speed. The image forming apparatus, wherein the drive source is controlled so that the drive source is rotated, and the drive source is stopped when the detection unit detects the recording material.

  According to the present invention, in a device using a low-power stepping motor, it is possible to return to a normal state from a state in which the elevating plate is urged by the feeding roller.

Schematic sectional view of the image forming apparatus of Examples 1 to 3, schematic perspective view of the sheet material feeding device Schematic perspective view of the paper feed cassettes of Examples 1 to 3, schematic perspective view showing the state of the lifting plate, schematic perspective view of the drive transmission path Flowchart of control sequence of embodiment 1 Time chart at the time of normal conveyance and out-of-step occurrence of the sheet material of Example 1 Flowchart of control sequence of embodiment 2 Time chart at the time of normal conveyance and out-of-step occurrence of the sheet material of Example 2 Flowchart of control sequence of embodiment 3

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Entire configuration of image forming apparatus]
Referring to FIG. 1A, a color image forming apparatus according to a first embodiment (hereinafter referred to as an image forming apparatus).
The overall configuration of 100 will be described. FIG. 1A is a schematic cross-sectional view of an image forming apparatus 100 including a sheet material feeding control mechanism. The image forming apparatus 100 is a four-color full-color laser printer using an electrophotographic process. The image forming apparatus 100 prints an image on a sheet material S that is a recording material based on an image signal input from an external host device such as a personal computer (hereinafter referred to as a PC) to a control unit 50 that is a controller of the image forming apparatus. Form. When receiving a print request such as an image signal from an external host device such as a PC, the control unit 50 instructs the image forming unit, the fixing device, the feeding control unit, and the like to start an image forming operation. The control unit 50 includes a ROM and a RAM. The ROM stores a control program and data executed by the control unit 50. The RAM temporarily stores a control program executed by the control unit 50. Memory used to store information. The control unit 50 has a timer function for measuring time.

  In the image forming apparatus 100, in order to form a full-color image on the sheet material S, the following control operation is executed. First, the photosensitive drums 1 of four process cartridges (hereinafter referred to as cartridges) PY, PM, PC, and PK that are image forming units are driven to rotate at a predetermined control speed in the counterclockwise direction (the arrow direction in the figure). Is done. The cartridge PY includes yellow toner, the cartridge PM includes magenta, the cartridge PC includes cyan, and the cartridge PK includes black toner. The belt 4 as an intermediate transfer member is also rotationally driven at a speed corresponding to the speed of the photosensitive drum 1 in the clockwise direction indicated by an arrow in the drawing. Further, the scanner unit 5 that forms an electrostatic latent image on the photosensitive drum 1 is also driven.

  In each cartridge PY, PM, PC, PK, the charging roller 2 uniformly charges the surface of the photosensitive drum 1 to have a predetermined polarity and potential at a predetermined control timing. Subsequently, the scanner unit 5 scans and exposes the surface of the photosensitive drum 1 of each cartridge PY, PM, PC, and PK with a laser beam modulated according to the image signal of each color. As a result, an electrostatic latent image corresponding to the image signal is formed on the surface of each photosensitive drum 1 that has been scanned and exposed with the laser beam. The electrostatic latent image formed on the surface of each photosensitive drum 1 is developed with the toner of the developing device 3 to form a toner image. By the image forming process operation described above, a toner image is formed on the photosensitive drum 1, and the toner images of the respective cartridges PY, PM, PC, and PK are rotated on the belt 4 that is rotationally driven at a speed corresponding to the speed of the photosensitive drum 1. Superimposed transfer.

  On the other hand, in the sheet material feeding device 10 that conveys the sheet material S, the sheet material S is brought into contact with a sheet material S placed on a lifting plate 16 (to be described later) of the sheet feeding cassette 9 at a predetermined control timing. The paper feed roller 6 and the transport roller 7 which are feeding means for feeding are driven. The sheet material S, which is a recording medium loaded on the paper feed cassette 9, is fed by the paper feed roller 6, separated one by one by the transport roller 7 and the separation roller 8, and fed to the transport path. When the registration sensor 101 serving as detection means for detecting the arrival of the sheet material S passes through the registration roller pair 11 and detects the leading edge of the sheet material S conveyed on the conveyance path, it notifies the control unit 50 of that fact. . At this time, the sheet material S is conveyed by the resist roller pair 11 so that the toner image transferred onto the belt 4 and the sheet material S conveyed by the conveying roller 7 reach the secondary transfer nip portion. The speed is adjusted.

  Thereafter, when the sheet material S is nipped and conveyed through the secondary transfer nip portion, which is the nip portion between the secondary transfer roller 12 and the belt 4, the four-color superimposed toner image formed on the belt 4 is transferred to the sheet material S. Transcribed. Subsequently, the sheet material S is separated from the surface of the belt 4, conveyed to the fixing device 13, heated and pressed at the fixing nip portion of the fixing device 13, and the color mixture of each color toner image on the sheet material S and the sheet. Fixing to the material S is performed. Then, the sheet material S is discharged onto the paper discharge tray 15 by the paper discharge roller pair 14. In addition, when the number of sheet materials S stacked on the sheet feeding cassette 9 becomes small, a separation pad 20 is provided on the elevating plate 16 described later so that the plurality of sheet materials S are not overlapped and fed. Is provided.

[Outline of sheet material feeding device]
Next, the configuration of the sheet material feeding device 10 will be described. FIG. 1B is a schematic perspective view of the sheet material feeding device. The sheet material feeding device 10 includes a sheet feeding cassette 9 for stacking the sheet material S, a lifting mechanism for lifting and lowering the lifting plate 16, a stepping motor 21 as a driving source, a sheet feeding roller 6, and a conveying roller 7. It is composed of a rotational drive transmission path. The sheet material feeding apparatus 10 according to the present exemplary embodiment has a sensor function that detects the presence or absence of the sheet material S placed on the lifting plate 16 and a sensor function that determines the type of the sheet material placed on the sheet feeding cassette 9. The sheet material detecting means such as is not provided. In addition, the description about the code | symbol attached | subjected to FIG.1 (b) is mentioned later.

[Paper cassette]
First, the paper feed cassette 9 will be described with reference to FIG. FIG. 2A is a schematic perspective view of the paper feed cassette 9. The paper feed cassette 9 is detachable from the front side of the image forming apparatus 100, which is the right side of the image forming apparatus 100 shown in FIG. 1A, and the user places the sheet material S and performs jam processing. Is configured to be easily performed. As shown in FIG. 2A, the sheet material S is placed on the sheet feeding cassette 9, and an elevating plate 16 that biases the sheet material S toward the sheet feeding roller 6 by performing a lifting operation described later. Is provided. The elevating plate 16 is positioned so as to be rotatable about the rotation center 36 of the elevating plate. Further, at both ends of the lift plate 16, engagement portions 17 with lift levers 18 that control the lift operation of the lift plate 16 are provided.

[Elevating mechanism of lifting plate]
Then, the raising / lowering mechanism of the raising / lowering board 16 is demonstrated. FIG. 2B is a schematic perspective view showing a state in which the elevating plate 16 is farthest from the paper feed roller 6 (not shown) (the most lowered state), and FIG. FIG. 6 is a schematic perspective view showing a state in which the paper feed roller 6 is in contact (the state in which it is raised most). On the main body side of the image forming apparatus 100, as shown in FIGS. 2B and 2C, the elevating lever 18 is positioned so as to be rotatable around the rotation center 37 of the elevating lever. The elevating lever 18 is urged in the direction of the paper feed roller 6 by an urging member (not shown). In the state in which the paper feed cassette 9 is mounted on the image forming apparatus 100, the engaging portion 17 of the elevating plate 16 and the elevating lever 18 are engaged, and the elevating plate 16 is interlocked with the elevating operation of the elevating lever 18. Is also configured to be movable up and down.

  Further, the lifting operation of the lifting lever 18 biased in the direction of the paper feed roller 6 is performed by a lifting plate lifting control cam 19 (hereinafter referred to as a control cam 19), which is a lifting means provided at the upper portion of the lifting lever 18. Be regulated. As shown in FIGS. 2B and 2C, when the control cam 19 is rotated, the elevating lever 18 is raised and lowered, and the elevating plate 16 is raised and lowered via the engaging portion 17 with the elevating lever. ing. That is, when the control cam 19 rotates in the direction of the arrow in the drawing from the state in which the elevating plate 16 is lowered as shown in FIG. 2B, the elevating plate 16 is moved in the direction of the paper feed roller 6 by an urging member not shown. Is moved along the shape of the control cam 19 and moved to the position shown in FIG. Further, when the control cam 19 is rotated, the lifting lever 18 is restrained downward by the control cam 19 in the drawing, so that the lifting plate 16 moves away from the paper feed roller 6, and FIG. Return to the state shown in b).

  The raising / lowering operation of the elevating plate 16 is repeated for each sheet material S, and the sheet material S placed on the elevating plate 16 is separated from the position where the sheet material S abuts against the paper feed roller 6 and is urged. The position is controlled by the rotation operation of the control cam 19. In addition, the separation pad 20 provided on the lifting plate 16 allows the sheet feeding roller 6 to pick up the sheet material S stacked on the uppermost surface when the sheet material S placed on the lifting plate 16 is reduced. The lowermost sheet material S is provided so as not to be double fed. The separation pad 20 is provided at a position facing the paper feed roller 6 as shown in FIG.

[Drive transmission path]
Next, a drive transmission path through which the rotation of the drive source is transmitted to the paper feed roller 6 and the transport roller 7 will be described with reference to FIG. FIG. 2D is a schematic perspective view showing a drive transmission path in the present embodiment. The image forming apparatus 100 includes a stepping motor 21 that is a drive source. The stepping motor 21 is driven by the control from the control unit 50, and the rotational drive of the stepping motor 21 is transmitted from the first drive gear 22 to the second drive gear 23. Here, the toothless gear 24 is a toothless gear controlled by a solenoid (not shown), and is configured to selectively mesh with the second drive gear 23. In the present embodiment, the meshing of the toothless gear 24 and the second drive gear 23 is controlled by a solenoid. However, a configuration in which the meshing is controlled using, for example, an electromagnetic clutch or the like may be used. The toothless gear 24 and the control cam 19 are fixed to the same rotation shaft 25 and are configured to rotate together. That is, when the solenoid operates based on the control signal from the control unit 50, the toothless gear 24 meshes with the second drive gear 23, and the driving of the stepping motor 21 is fixed to the same rotating shaft 25 via the toothless gear 24. The control cam 19 is rotated.

  A gear 27 is also fixed to the rotary shaft 25 to which the toothless gear 24 and the control cam 19 are fixed. When the gear 27 rotates, the gear 31 engaged with the gear 27 also rotates. A tooth surface that meshes with the gear 31 is formed at the ends of the paper feed roller 6 and the transport roller 7, and the paper feed roller 6 and the transport roller 7 are rotationally driven by the rotation of the gear 31. Here, the conveyance distance of the sheet material S by the paper feed roller 6 and the conveyance roller 7 is such that the sheet material S can be conveyed to the registration roller pair 11 downstream of the conveyance path by the rotation operation of the missing gear 24 and the control cam 19. Is set to

  As described above, the stepping motor 21 and the control cam 19 are interlocked, and the control cam 19 makes one rotation so that the lifting plate 16 can be brought into contact with and separated from the paper feed roller 6. Therefore, when the stepping motor 21 steps out at the position where the lifting plate 16 is urged against the feeding roller 6, the lifting plate 16 and the feeding roller 6 are in contact with each other even if the user reinserts the sheet material S. Therefore, the leading edge of the sheet material S does not enter between the elevating plate 16 and the paper feed roller 6. Therefore, the sheet material cannot be placed at the normal position of the paper feed roller 6.

  More specifically, since the elevating lever 18 is provided on the main body side of the apparatus 100, when the paper feeding cassette 9 is taken out from the main body, the engagement between the engaging portion 17 and the elevating lever 18 is released, and the elevating plate 16 is in the most lowered state. Therefore, the user can place the sheet material S on the lifting plate 16. However, when the paper feed cassette 9 is attached to the main body again in this state, the lift lever 18 on the main body side remains in the raised state, so that before the leading edge of the sheet material S enters between the lift plate 16 and the paper feed roller 6. The elevating plate 16 is raised. Therefore, the leading edge of the sheet material S collides with the paper feed roller 6, and the user cannot place the sheet material S at the normal position of the paper feed roller 6.

[Control sequence of feeding operation]
Next, the feeding operation of this embodiment will be described using the flowchart of FIG. FIG. 3 is a flowchart showing a control sequence of the feeding operation of the present embodiment. When a print request is received from an external host device such as a PC, the processing shown in FIG. First, in step 101 (hereinafter referred to as S101), the control unit 50 instructs the image forming unit, the fixing device, the feeding control unit, etc. to start an image forming operation, resets and starts the timer. .

In step S <b> 102, the stepping motor 21 instructed to disclose the image forming operation from the control unit 50 starts accelerating rotation at the start timing of the feeding operation, and rotates the same as the missing gear 24 via the missing gear 24. The control cam 19 fixed to the shaft is rotated. As described above, when the control cam 19 rotates, the elevating lever 18 rises, and the elevating plate 16 starts to rise via the engaging portion 17 with the elevating lever 18. When the lifting plate 16 on which the sheet material S is stacked performs a lifting operation, the uppermost sheet material S of the lifting plate 16 and the paper feed roller 6 come into contact with each other. In addition, the feed roller 6 and the transport roller 7 are rotationally driven in response to the rotation of the gear 31 that is rotationally driven by the gear 27 on the same rotational axis as the control cam 19. Such a normal feeding operation of the sheet material feeding apparatus 10 is hereinafter referred to as a “first driving operation”. The sheet material S, which is a recording medium stacked on the lifting plate 16 of the paper feed cassette 9, is fed by the paper feed roller 6, and separated and transported one by one by the transport roller 7 and the separation roller 8. The road is fed.

  In S <b> 103, the control unit 50 determines whether the sheet material S is normally conveyed on the conveyance path based on whether the notification that the sheet material S is detected is received from the registration sensor 101. When the control unit 50 receives the notification that the leading edge of the sheet material S is detected from the registration sensor 101, the control unit 50 determines that the sheet material S is normally conveyed on the conveyance path, proceeds to S105, and has not received it. In the case, the process proceeds to S104. In S <b> 104, the control unit 50 reads the timer value from the timer, and determines whether or not a first predetermined time, which is a time from when the sheet material S starts to be fed, to the registration sensor 101 has elapsed. When it is determined that the first predetermined time has not elapsed, the control unit 50 returns to S103, and when it is determined that the first predetermined time has elapsed, the control unit 50 proceeds to S109.

  In S <b> 105, the control unit 50 conveys the sheet material S by the registration roller pair 11 that conveys the sheet material S in order to match the toner image transferred onto the belt 4 and the transfer position to the fed sheet material S. Adjust the speed. When the adjustment is completed, the controller 50 transfers the sheet material S to the secondary transfer nip portion in order to transfer the toner image on the belt 4 to the sheet material S. In S <b> 106, the control unit 50 separates the sheet material S to which the toner image has been transferred from the belt 4 and conveys the sheet material S to the fixing device 13. The control unit 50 heats and pressurizes the sheet material S at the fixing nip portion of the fixing device 13, causes the toner image to be fixed to the sheet material, and discharges the sheet material S after the fixing process to the outside.

  In S107, the control unit 50 determines whether or not all printing has been completed, and if not completed, the process returns to S101, and if completed, the process proceeds to S108. In S108, the control unit 50 instructs the image forming unit, the fixing device, the feeding control unit, etc. to stop the image forming operation, and ends the processing.

  Before describing the processing after S109, the operation of the stepping motor 21 when the sheet material S is not placed on the sheet feeding cassette 9 will be described. When there is no sheet material S on the sheet feeding cassette 9, the elevating plate 16 is lifted so that the separation pad 20 provided on the elevating plate 16 comes into contact with the sheet feeding roller 6 and is urged ( Pressed state). In order to prevent the lowermost sheet material S from being dragged by the sheet material S placed on the upper side even when sheet materials of various paper types are placed on the lifting plate 16, the friction coefficient of the separation pad 20 is It is set high. Therefore, rotating the stepping motor 21 while the separation pad 20 is in contact with the paper feed roller 6 places an excessive load on the stepping motor 21 that is the drive source of the paper feed roller 6. 21 may step out. In the present embodiment, the step-out refers to the case where the stepping motor 21 is stopped due to the stop of the paper feed roller 6. That is, it indicates a case where the stepping motor 21 is stopped due to an excessive load applied from the outside. Further, when the stepping motor 21 steps out, the elevating plate 16 stops in a state where it is urged against the sheet feeding roller 6, and therefore the stepping motor 21 steps out again even when the sheet feeding is started again. Will end up.

Therefore, when the first predetermined time has elapsed in S104, the control unit 50 determines that the stepping motor 21 has stepped out. In S109, the control unit 50 performs a “second drive operation” in which the stepping motor 21 is rotated at a low speed rotation (second rotation speed) in the self-activation region for a predetermined time in order to return from the step-out state due to overload. Do. As a result, the control cam 19 is rotated, and the elevating plate 16 is moved to a position separated from the paper feed roller 6. Furthermore, the control unit 50 resets and starts a timer to measure a second predetermined time which is a predetermined time for performing the second driving operation. In the present embodiment, the second predetermined time is the time required for rotating the control cam 19 to return the elevating plate 16 to the normal position which is the position farthest from the paper feed roller 6 (FIG. 2B). And In S110, the control unit 50 reads the timer value from the timer, determines whether or not the second predetermined time has elapsed, proceeds to S111 if it has elapsed, and repeats the processing of S110 if it has not elapsed. In S111, the control unit 50 stops the second driving operation by the sheet material feeding device 10 and ends the process.

[Time chart of feeding operation]
The driving operation of the above stepping motor 21 will be described in detail using a time chart. FIG. 4 is a time chart of the flowchart of FIG. 3. FIG. 4A shows a case where the sheet material S is placed on the paper feed cassette 9, and FIG. 6 is a time chart when S is not placed in the paper feed cassette 9; 4A and 4B, the vertical axis represents the motor rotation speed (unit: rad / s (radian / second)) of the stepping motor 21, and the horizontal axis represents time (unit: s (second)). Also, a code starting from T (for example, T101) in the figure indicates a time timing, and the number in the code corresponds to a step number starting with S attached to each process in the flowchart described in FIG.

  In FIG. 4A, when sheet feeding is started at time timing T101 (hereinafter simply referred to as T101) (S101 in FIG. 3), the rotation speed of the stepping motor 21 is increased. At T102, when the feeding operation start timing (sheet material S pickup timing) is reached, the first driving operation is performed (S102 in FIG. 3). Thereby, the rotational speed of the stepping motor 21 is driven in a high speed region (first rotational speed), and the sheet material S is fed. When the registration sensor 101 detects the leading edge of the sheet material S at T103 (YES in S103 in FIG. 3), the conveyance speed of the sheet material S is adjusted by the registration roller pair 11 that conveys the sheet material S (S105 in FIG. 3). When the adjustment is completed, the sheet material S is conveyed to the secondary transfer nip portion at T105 (S105 in FIG. 3). At T106, the sheet material S to which the toner image has been transferred is conveyed to the fixing device 13, and the toner image is fixed to the sheet material. The sheet material S for which the fixing process has been completed is discharged out of the apparatus. Then, feeding of the second sheet material S is started (S101 in FIG. 3).

Then, the time chart of FIG.4 (b) is demonstrated. In the image forming apparatus 100 of this embodiment, since the sheet material presence / absence sensor is not provided in the sheet feeding cassette 9, even in a state where the sheet material S does not exist in the sheet feeding cassette 9, as in FIG. Thus, the first driving operation is performed (S101 in FIG. 3). As a result, even when the separation pad 20 and the paper feed roller 6 come into contact with each other and the stepping motor 21 is overloaded, the stepping motor 21 operates as it is at a high speed. If it is the first printing after printing (printing) is started, the rotational speed of the stepping motor 21 is being accelerated as shown in the feeding operation start timing (T102) in FIG. 4B. An overload condition occurs at the timing of pickup without the sheet material S. In addition, when there is no sheet material at the time of printing on the second and subsequent sheet materials S from the start of printing, a constant speed (first time after transporting to the fixing device (T106 in FIG. 4A)). In the state of the number of rotations), an overload state occurs when the next sheet material is picked up by the sheet feeding roller 6. If the stepping motor 21 steps out due to an overload state while the motor is accelerating, control becomes impossible, and even if the feeding operation ends, the stepping motor 21 does not return from the step out state. Even if the user tries printing again and repeats the feeding start (S101 in FIG. 3), the stepping motor 21 steps out again when the separation pad 20 and the paper feed roller 6 are in contact with each other. Further, in a state where the elevating plate 16 is stopped at a position where it is urged (pressed) against the paper feed roller 6, even if the user reinserts the sheet material S into the paper feed cassette 9, the leading end of the sheet material S in the transport direction is The jam occurs between the lifting plate 16 and the paper feed roller 6.

  Therefore, in FIG. 4B, the absence of the sheet material S causes the stepping motor 21 to step out at T102. As a result, since the sheet material S is not conveyed, the registration sensor 101 does not detect the sheet material S at T103 after the first predetermined time has elapsed from T101 (timeout) (YES in S104 in FIG. 3). The driving operation is started (S109 in FIG. 3). As described above, the second driving operation refers to rotating the stepping motor 21 at a low speed rotation (second rotation speed) in the self-starting region, and the second rotation speed is the first rotation described above. The number of rotations is smaller than the number. Here, the self-starting region of the stepping motor is a general basic characteristic of the stepping motor, and means an initial speed of the stepping motor that can be started in synchronization with a pulse signal input from the outside to the stepping motor. Then, when a second predetermined time during which the second driving operation is performed elapses, the second driving operation is stopped at T111, and the elevating plate 16 is positioned farthest from the sheet feeding roller 6 (FIG. 2B). ) To stop.

  By driving the stepping motor in the self-starting region, even if a step-out occurs, the separation pad 20 and the paper feed roller 6 come into contact with each other because the rotation is started again in synchronization with the pulse signal input from the outside. It is possible to escape from a state where an excessive load is applied. In general, the output torque of the motor is higher at low speed than at high speed. Therefore, by rotating at low speed in the self-starting region, the separation pad 20 and the paper feeding cause of the overload state of the stepping motor 21 are supplied. The contact state of the roller 6 can be returned to the separated state.

  As described above, according to the present embodiment, in the apparatus using the low output stepping motor, the state where the lifting plate is urged by the feeding roller can be returned to the normal state. Even when the user forgets to put the sheet material into the sheet feeding cassette, the lifting plate is stopped in a state where it is urged by the feeding roller, and the state where the sheet material cannot be placed is avoided. Since an inexpensive stepping motor with a low output required for the feeding operation can be mounted, the cost can be reduced.

  Further, in this embodiment, it is assumed that the separation pad 20 is provided on the lifting plate 16. However, the separation pad 20 is not necessarily provided. The present invention can also be applied to a configuration in which the stepping motor 21 steps out even when the paper feed roller 6 comes into contact with a portion having a lower friction coefficient than the separation pad 20.

  In this embodiment, the control when the sheet material S is not stacked on the sheet feeding cassette 9 has been described. However, when the sheet material S stays in the conveyance path from the sheet feeding cassette 9 to the registration sensor 101 ( It can also be applied to jams). When the jam occurs, the lifting plate 16 is lowered, so that the user can easily perform the jam processing.

  Further, in this embodiment, the elevating plate 16 is lowered to the state where it is farthest from the paper feed roller 6. However, the elevating plate 16 is lowered to the extent that it can escape from the step-out state and can accommodate even one sheet material S. The structure to be made may be sufficient.

In the first embodiment, when the sheet material is not placed on the sheet feeding cassette, the stepping motor is stepped out by the contact between the sheet feeding roller and the separation pad, and the second driving operation is driven for a predetermined time. The configuration for separating the paper feed roller and the separation pad has been described. In Example 2,
A second driving operation in the case where the stepping motor has stepped out due to the user setting to print a sheet material different from the paper type of the sheet material placed on the paper feed cassette will be described. Also in this embodiment, the image forming apparatus 100 and the sheet material feeding apparatus 10 described in FIGS. 1 and 2 of the first embodiment are used, and the same components as those in the first embodiment are denoted by the same reference numerals. The description is omitted.

[Control sequence of feeding operation]
First, the feeding operation of this embodiment will be described with reference to the flowchart of FIG. FIG. 5 is a flowchart showing a control sequence of the feeding operation of this embodiment. When a print request is received from an external host device such as a PC, the processing shown in FIG. In FIG. 5, the same step numbers are assigned to the same processes as those shown in FIG. 3 of the first embodiment.

  In FIG. 5, the processing described in FIG. 3 of the first embodiment is performed for S <b> 101 to S <b> 108, which are processing when the sheet material S is normally conveyed and printed, and thus description thereof is omitted here. . In the present embodiment, a second driving operation in the case where the user prints a sheet material of a paper type different from the paper type of the sheet material S placed on the paper feed cassette will be described. For example, a sheet material of a specific paper type such as thick paper performs a fixing operation and a feeding operation at a low speed in order to improve the fixing performance of each color toner image in the fixing device 13, as shown in FIG. There is a need. In this case, while the sheet material S is curved around the conveyance roller 7, the sheet material S is fed at a low speed on the conveyance path to the registration roller pair 11 at a lower conveyance speed than normal. However, when the user sets the sheet material placed on the paper feed cassette 9 as a normal sheet material, the sheet material such as cardboard placed on the paper feed cassette 9 is fed at a high conveyance speed. It will be. Therefore, an excessive load is applied to the stepping motor 21 that is a driving source of the sheet feeding roller 6 by applying an excessive load to the sheet feeding roller 6 or the like with a hard sheet material such as thick paper, and the stepping motor 21 is removed. Cause a tone. Since the stepping motor 21 has stepped out due to an excessive load, the sheet material S is not conveyed while remaining on the conveying path, and even if the first predetermined time has elapsed from the start of feeding, the registration sensor 101 does not move. The tip of the material S is not detected (S104 YES).

  Therefore, in S120, the control unit 50 performs a second drive operation for rotating the stepping motor 21 for a predetermined time at a low speed rotation in the self-starting region, as in the first embodiment. Furthermore, the control unit 50 resets and starts a timer to measure a second predetermined time which is a predetermined time for performing the second driving operation. In S121, the control unit 50 reads the timer value from the timer, determines whether or not the second predetermined time has elapsed, proceeds to S122 if it has elapsed, and proceeds to S123 if it has not elapsed. In S122, the control unit 50 stops the second driving operation by the sheet material feeding apparatus 10 and ends the process. At this time, the lift plate 16 is stopped at a position farthest from the paper feed roller 6 (FIG. 2B), as in the first embodiment.

In S123, the control unit 50 determines whether or not the stepping motor 21 has come out of the step-out state depending on whether or not the notification that the sheet material S is detected is received from the registration sensor 101, and whether or not the sheet material S is normally conveyed on the conveyance path. Judging. In other words, in the present embodiment, the sheet material feeding apparatus 10 does not perform the feeding process at the conveyance speed corresponding to the paper type of the sheet material S. It is in a stopped state. However, in the present embodiment, the stepping motor 21 is driven at a low speed rotation by the second driving operation, so that the step-out state is released, and the sheet feeding roller 6 and the conveying roller 7 are driven, whereby the sheet material S is driven. Is resumed. As a result, the sheet material S is conveyed on the conveyance path, the sheet material S passes through the registration roller pair 11, and the leading edge of the sheet material S is detected by the registration sensor 101. The control unit 50 returns to the process of S121 if it has not received the notification of detecting the leading edge of the sheet material S from the registration sensor 101, and if it has received the notification, the stepping motor 21 returns from the step-out state. Then, it is determined that the sheet material S has been normally conveyed, and the process proceeds to S124.

  In S124, the control unit 50 stops the second driving operation by the sheet material feeding apparatus 10, and ends the process. At this time, since the second predetermined time has not elapsed, the lifting plate 16 is in the middle of being separated from the position where the paper feeding roller 6 is in contact with the sheet material S (while it is being lowered). The driving operation is stopped. Therefore, the control cam 19 described in the first embodiment is continuously rotated for the second predetermined time to make one rotation, and the elevating plate 16 is located at the position farthest from the paper feed roller 6 (FIG. 2B). This is different from the return control. Since the elevating plate 16 is not lifted or lowered to a position sufficiently separated from the paper feed roller 6, the user may not be able to fully load the sheet material into the paper feed cassette 9. However, although in the middle of the second driving operation, the operation of the stepping motor 21 is stopped at the timing when the sheet material S is detected by the registration sensor 101, so that the sheet material S is located downstream of the conveyance path from the registration sensor 101. The situation where it is conveyed can be avoided. In S120, when the second driving operation is started, driving of the fixing device 13 and the like related to image formation is stopped. In this case, when the sheet material S is conveyed downstream of the registration sensor 101 in the conveyance path, the sheet material S stays in the vicinity of the fixing device 13 and jamming processing becomes difficult. Therefore, it is desirable to avoid a situation in which the sheet material S is conveyed downstream of the registration sensor 101 in the conveyance path. As described above, since the sheet material S is stopped in the vicinity of the registration sensor 101, it is possible to easily perform the jam processing operation by the user as compared with the case where the operation is performed downstream of the conveyance path.

[Time chart of feeding operation]
The driving operation of the above stepping motor 21 will be described using a time chart. FIG. 6 is a time chart of the flowchart of FIG. 6A shows a case where a sheet material S of the correct paper type is placed in the paper feed cassette 9, and FIG. 6B shows a sheet material S of a paper type different from the paper type of the designated sheet material. Is a time chart when the paper is placed in the paper feed cassette 9. 6A and 6B, the vertical axis represents the motor rotation speed (unit: rad / s (radian / second)) of the stepping motor 21, and the horizontal axis represents time (unit: s (second)). In FIG. 6A, the rotation speed of the stepping motor 21 in the case of a normal sheet material is indicated by a broken line, and the rotation speed in the case of a specific sheet material such as cardboard is indicated by a solid line. As shown in FIG. 6A, when the sheet material S is thick paper, it is understood that the conveyance operation is performed at a low conveyance speed while suppressing the number of rotations of the stepping motor 21 as compared with a normal sheet material. . In the figure, a code beginning with T (for example, T101) indicates a time timing, and the number in the code corresponds to a step number starting with S attached to each process in the flowchart described in FIG. The time chart of FIG. 6A shows the time shown in FIG. 4A described in the first embodiment except that the sheet material S is thick paper and the rotation speed of the stepping motor is slower than that of the first embodiment. This is the same as the chart, and the description is omitted.

  Next, the time chart of FIG. 6B will be described. As in FIG. 6A, the first drive operation is performed at T101 (S101 in FIG. 5), and the stepping motor 21 operates at a high speed. If it is the first printing after the start of printing (printing), as shown in the start timing (T102) of the feeding operation in FIG. Is carried out. However, since the sheet material S placed in the paper feed cassette 9 is a thick paper of a paper type different from the designated plain paper, an excessive load is applied to the paper feed roller 6 and the transport roller 7. As a result, the stepping motor 21 is overloaded while being driven at a high speed, which is a predetermined rotation speed, and is in a step-out state. Therefore, the sheet material S is stopped on the conveyance path. As a result, since the registration sensor 101 does not detect the sheet material S at T103 after the first predetermined time has elapsed from T101 (YES in S104 in FIG. 5), the second driving operation is started at T120 (S120 in FIG. 5). ).

  By the second driving operation, the stepping motor 21 is driven at a low speed rotation to escape the step-out state, and the sheet feeding roller 6 and the conveying roller 7 are driven, whereby the conveyance of the sheet material S is resumed. As a result, the sheet material S is conveyed on the conveyance path, the sheet material S passes through the registration roller pair 11, and the registration sensor 101 detects the leading edge of the sheet material S (YES in S123 in FIG. 5). At T124 when the sheet material S is detected, the second driving operation by the sheet material feeding apparatus 10 is stopped (S124 in FIG. 5).

  On the other hand, when the sheet material S is not placed in the paper feed cassette as in the first embodiment, when a predetermined time required for the second driving operation has elapsed (YES in S121 in FIG. 5), at T122. The second driving operation by the sheet material feeding apparatus 10 is stopped (S122 in FIG. 5). At this time, as in the first embodiment, the elevating plate 16 is positioned farthest from the paper feed roller 6 (FIG. 2B).

  In this embodiment, at the timing when the registration sensor 101 detects the sheet material S, the operation of the stepping motor 21 is stopped. However, the anteroposterior relationship between the separation timing of the lifting plate 16 with respect to the paper feed roller 6 and the timing at which the registration sensor 101 detects the sheet material S differs depending on the shape of the control cam 19, the installation position of the registration sensor 101, and the feeding path. Therefore, the time for stopping the second driving operation may be changed as appropriate in accordance with the timing at which the registration sensor 101 detects the sheet material S. As described above, according to the present embodiment, in the apparatus using the low output stepping motor, the state where the lifting plate is urged by the feeding roller can be returned to the normal state.

  In the second driving operation of the stepping motors of the first and second embodiments, the rotation control of the stepping motor is a low-speed rotation in the self-starting area. In Example 3, an embodiment will be described in which the stepping motor in the second driving operation is temporarily controlled at a high output by increasing the current value for driving the stepping motor. Also in this embodiment, the image forming apparatus 100 and the sheet material feeding apparatus 10 described in FIGS. 1 and 2 of the first embodiment are used, and the same components as those in the first embodiment are denoted by the same reference numerals. The description is omitted.

[Control sequence of feeding operation]
The feeding operation of the present embodiment will be described using the flowchart of FIG. FIG. 7 is a flowchart showing the control sequence of the feeding operation of this embodiment. When a print request is received from an external host device such as a PC, the control unit 50 executes the process shown in FIG. In FIG. 7, the same steps as those shown in FIG. 3 of the first embodiment are denoted by the same step numbers.

  In FIG. 7, the processing described in FIG. 3 of the first embodiment is performed for S101 to S108, which are processing performed when the sheet material S is normally conveyed and printed, and thus description thereof is omitted here. . In S <b> 104, the control unit 50 reads the timer value from the timer, and determines whether or not a first predetermined time, which is a time from when the sheet material S starts to be fed, to the registration sensor 101 has elapsed. When it is determined that the first predetermined time has not elapsed, the control unit 50 returns to S103, and when it is determined that the first predetermined time has elapsed, the control unit 50 proceeds to S301.

Therefore, in S301, the control unit 50 causes the stepping motor 21 to have a current value higher than the first and second embodiments by a predetermined time, that is, a current value larger than the current value (first current value) at the time of the first driving operation. A third driving operation for rotating at a high output by the value (second current value) is performed. Further, the control unit 50 resets and starts a timer to measure a third predetermined time which is a predetermined time for performing the third driving operation. In the present embodiment, the output value of the stepping motor is increased compared with the first and second embodiments by temporarily increasing the current value of the drive current, and the recovery from the step-out state is performed. Note that the speed of the stepping motor 21 may be increased to the same acceleration state as in the first driving operation. The reason why the current value is not constantly increased in the first driving operation in the first and second embodiments described above is that the temperature value of the stepping motor 21 increases or noise is generated by increasing the current value of the stepping motor 21. It is to do. Therefore, in this embodiment, it cannot be applied to the first driving operation which is a normal feeding operation, but only when the third driving operation is performed, the current value of the stepping motor 21 is temporarily increased. The elevating plate 16 is controlled to move to a position separated from the paper feed roller 6.

  In S302, the control unit 50 reads the timer value from the timer, determines whether or not a third predetermined time has elapsed, proceeds to S303 if it has elapsed, and repeats the processing in S302 if it has not elapsed. Since the rotation speed of the stepping motor 21 is higher than those in the first and second embodiments, the third predetermined time is set according to the rotation speed, and is set shorter than the second predetermined time described above. In S303, the control unit 50 stops the third driving operation by the sheet material feeding apparatus 10 and ends the process. At this time, the lift plate 16 is stopped at a position farthest from the paper feed roller 6 (FIG. 2B), as in the first embodiment. In this embodiment, the rotation speed for returning the stepping motor 21 from the step-out state is made faster than those in the first and second embodiments, so that the stepping motor 21 is returned from the step-out state earlier than in the first and second embodiments. be able to. This is because if the number of revolutions is high, the time required for the lifting plate 16 to return to the most separated position (FIG. 2 (b)) can be shortened. In the apparatus using the stepping motor, it is possible to return to the normal state from the state where the lifting plate is urged by the feeding roller.

  In the above embodiment, the friction coefficient of the surface of the paper feed roller 6 is reduced by the influence of the surrounding humidity and the like, and the paper feed roller 6 may continue to rotate without the stepping motor 21 stepping out. For example, in the first embodiment, when the sheet material S is not stacked on the sheet feeding cassette 9, the stepping motor 21 is stepped out by the contact between the sheet feeding roller 6 and the separation pad 20. However, since the friction coefficient of the surface of the paper feed roller 6 is reduced, the stepping motor 21 may not step out even if the paper feed roller 6 and the separation pad 20 come into contact with each other. In this case, the paper feed roller 6 continues to rotate and the lift plate 16 also descends. On the other hand, since the sheet material S is not fed from the sheet feeding cassette 9, according to the flowchart of FIG. 3, the control unit 50 executes the second driving operation (S109). That is, the control unit 50 performs the second driving operation even though the lifting plate 16 has already been lowered.

  At this time, the following problems occur. That is, if the second driving operation is further performed in a state where the elevating plate 16 has already been lowered, the elevating plate 16 will be raised conversely. As a countermeasure against this, in the above-described embodiment, the meshing between the missing gear 24 and the second drive gear 23 is controlled by a solenoid (not shown). When the solenoid is turned on, the missing tooth gear 24 starts to rotate. Then, when the toothless gear 24 goes around, it stops meshing with the second drive gear 23 and stops rotating. As long as the solenoid is not turned on again, the power of the stepping motor 21 is not transmitted. Therefore, when the second driving operation is executed, the stepping motor 21 is rotated without turning on the solenoid. As a result, when the lifting plate 16 has already been lowered, since the missing gear 24 does not rotate even if the stepping motor 21 is rotated, the lifting plate 16 does not rise. On the other hand, it is possible to return from the state where the paper feed roller 6 and the lift plate 16 are in contact with each other.

In the above-described embodiment, the configuration in which the sheet material S is fed from the sheet feeding cassette 9 has been described. However, it is not limited to this configuration. For example, the above-described embodiment can be applied to a configuration in which the sheet material S is fed from a manual feed tray or a multi-tray.
That is, the above-described embodiment can be applied to any unit configured to raise the lifting plate and feed the sheet material S placed on the lifting plate.

6 Feeding roller 16 Lifting plate 19 Lifting plate lifting control cam 21 Stepping motor 50 Control unit

Claims (16)

An elevating plate on which a recording material can be placed and raised and lowered;
Elevating means for elevating the elevating plate;
A feeding unit that abuts the recording material placed on the elevation plate raised by the elevation unit and feeds the abutted recording material by rotating;
A driving source for driving the elevating means and the feeding means by rotating;
Control means for controlling the drive source so that the drive source rotates;
Setting means for setting the type of recording material;
Have
The recording material set by the setting means while the control means controls the drive source so that the drive source rotates at a first rotation speed corresponding to the type of the recording material set by the setting means. In a state where a recording material of a type different from the type is placed on the elevating plate, the feeding means comes into contact with the recording material placed on the elevating plate and the feeding means cannot rotate. When a state occurs, the control means controls the drive source so that the drive source rotates at a second rotation speed that is slower than the first rotation speed, and the feeding means moves to the lifting plate. An image forming apparatus, wherein the drive source is stopped in a state of being separated from a recording material placed thereon.   The control means starts controlling the drive source so that the drive source rotates at the first rotation speed in a state where the feeding means is not in contact with the recording material placed on the lifting plate. Accordingly, the elevating means raises the elevating plate, the feeding means rotates, and the control means controls the drive source so that the drive source rotates at the first rotational speed. In the meantime, the feeding means changes from a state of not contacting the recording material placed on the lifting plate to a state of contacting the recording material placed on the lifting plate. The image forming apparatus according to claim 1. The image forming apparatus according to claim 1, wherein the different types of recording materials are recording materials having different thicknesses. Having a detecting means for detecting the recording material fed by the feeding means,
When the detection unit does not detect the recording material until a predetermined time elapses after the control unit controls the drive source so that the drive source rotates at the first rotation speed, the control unit 4. The image forming apparatus according to claim 1, wherein it is determined that a state where the feeding unit cannot rotate occurs.   The predetermined time is determined when the feeding source is rotating at the first rotational speed and the feeding unit starts feeding the recording material placed on the lifting plate, and then feeding the recording material. The image forming apparatus according to claim 4, wherein the time required for the leading end of the recording material in the conveyance direction to reach the detection unit. An elevating plate on which a recording material can be placed and raised and lowered;
Elevating means for elevating the elevating plate;
A feeding unit that abuts the recording material placed on the elevation plate raised by the elevation unit and feeds the abutted recording material by rotating;
Detecting means for detecting the recording material fed by the feeding means;
A driving source for driving the elevating means and the feeding means by rotating;
Control means for controlling the drive source so that the drive source rotates;
Setting means for setting the type of recording material;
Have
The recording material set by the setting means while the control means controls the drive source so that the drive source rotates at a first rotation speed corresponding to the type of the recording material set by the setting means. In a state where a recording material of a type different from the type is placed on the elevating plate, the feeding means comes into contact with the recording material placed on the elevating plate and the feeding means cannot rotate. When a state occurs, the control means controls the drive source so that the drive source rotates at a second rotation speed that is slower than the first rotation speed, and the detection means detects the recording material. In the case, the image forming apparatus is characterized in that the drive source is stopped.   When the detection unit does not detect the recording material until a predetermined time elapses after the control unit controls the drive source so that the drive source rotates at the first rotation speed, the control unit The image forming apparatus according to claim 6, wherein it is determined that a state where the feeding unit cannot rotate occurs.   The predetermined time is determined when the feeding source is rotating at the first rotational speed and the feeding unit starts feeding the recording material placed on the lifting plate, and then feeding the recording material. The image forming apparatus according to claim 7, wherein the time required for the leading end of the recording material in the conveyance direction to reach the detection unit. Having image forming means for forming an image on a recording material;
The detection means is provided between the feeding means and the image forming means,
Claim 4 wherein the drive source at said second rotational speed while the control means so as to rotate is controlling the drive source, the operation of the image forming means is characterized by being stopped, 5 The image forming apparatus according to claim 1 , 7 or 8. The said raising / lowering means has a cam which rotates in response to the drive from the said drive source, The said raising / lowering board raises once and descend | falls when the said cam rotates once . The image forming apparatus according to any one of 7 to 9.   The elevating means is a first gear that rotates in response to driving from the drive source, and a second gear that rotates by engaging with the first gear, and the first gear rotates once. A second gear that is disengaged from the second gear, a rotary shaft to which the second gear and the cam are fixed, and the first gear and the second gear are engaged with each other from the drive source. The image forming apparatus according to claim 10, further comprising: a solenoid that transmits the drive of the motor to the cam.   The first gear and the second gear are engaged, the control means controls the solenoid so as to transmit the drive from the drive source to the cam, and at the first rotational speed, If the detection means does not detect the recording material before the predetermined time elapses after the control means controls the drive source so that the drive source rotates, the control means controls the solenoid again. The image forming apparatus according to claim 11, wherein the drive source is controlled such that the drive source rotates at the second rotation speed. The drive source is a stepping motor;
13. The image forming apparatus according to claim 1, wherein the second rotation speed is the slowest rotation speed in a speed range in which the stepping motor can rotate.   The elevating means raises the elevating plate to bring the recording material placed on the elevating plate into contact with the feeding means, lowers the elevating plate, and records placed on the elevating plate The image forming apparatus according to claim 1, wherein the material is separated from the feeding unit.   The image forming apparatus according to claim 1, wherein the control unit changes the first rotation speed in accordance with a type of the recording material set by the setting unit. .   The image according to any one of claims 1 to 15, wherein the elevating unit raises and lowers the elevating plate once each time the feeding unit feeds one recording material. Forming equipment.

Images