JP7456222B2 - Conveyance device and image forming device - Google Patents

Description

The present invention relates to a conveyance device and an image forming apparatus.

Patent Document 1 aims to provide a cut sheet feeding device that can prolong the life of the paper feeding roller and reduce stress on cut sheets, and is a cut sheet feeding device that has a double feeding prevention mechanism. , a means for detecting an inter-sheet friction coefficient, a means for detecting a cut sheet feeding frequency, a means for detecting a cut sheet conveyance speed in a paper feeding process, and a control section, and the control section has a control section. It is disclosed that the magnitude of sheet handling force in a double-feed prevention mechanism is changed and controlled based on a combination of detection results by two detection means.

Furthermore, Patent Document 2 aims to provide a paper feeding device that can reliably prevent the occurrence of double feeding and non-feeding of sheets, and can also distinguish between double feeding and thick paper. This is a paper feeding device that separates and feeds sheets one by one, and is composed of a feed roller that conveys the sheet-like object in the conveying direction and a reverse roller that is provided opposite to this feed roller. A separation means for separating the sheet-like material conveyed between the rollers one by one; a thickness detection means for detecting the thickness of the sheet-like material separated by the separation means; and a thickness detection means for detecting the thickness of the sheet-like material separated by the separation means. A control means for controlling the push-back force of the reverse roller based on detected information regarding the thickness of the sheet-like body is disclosed.

Furthermore, Patent Document 3 discloses that abnormal conveyance of sheets is prevented by simple control of the drive current of a separation member drive motor that rotates a separation member, and that a nip portion, which is a portion in which a rotating paper feeding member and a separation member come into pressure contact, is disclosed. In order to be able to determine in a simple way the double feeding state of sheets conveyed to the If the rotation of the separation roll Rs2 reverses when the initial value Ia is increased toward the upper limit value Ib and the rotation reaches the upper limit value, it is determined that there is double feeding, and the current value Ic at the time when the reverse rotation starts is maintained. However, when the rotation of the separation roll Rs2 changes from reverse rotation to driven (co-rotation), it is determined that the sheet on the separation roll Rs2 side has moved to the upstream side of the nip N, and after that, the sheet is moved to the downstream side. It is disclosed to control the separation roll drive current I so that the separation roll is not conveyed.

However, conventional torque control of the reverse motor that drives the reverse roller (separation roller) has been performed based on the measured value of the motor current, which has been problematic in that it is relatively expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a conveyance device that can control the torque of a reverse motor at a lower cost than conventional ones.

The conveying device according to the present invention includes a sheet loading means for loading sheets, a pickup roller that is rotated in the sheet conveying direction in contact with the uppermost sheet of the sheets stacked on the sheet loading means, and a pickup roller for conveying the sheets. a feed roller that is rotationally driven to feed the feed roller in a direction, a first drive source for rotationally driving the pickup roller and the feed roller, a first encoder that detects the amount of rotation of the first drive source, and a first encoder that detects the amount of rotation of the first drive source; a first drive control means for controlling the speed of the first drive source based on the amount of rotation detected by a first encoder; a separate roller that presses and holds the sheet together with the feed roller; and a means for rotationally driving the separate roller. a second drive source, a second encoder that detects the amount of rotation of the second drive source, a second drive control means that torque controls the second drive source, and a pressure that presses the separate roller against the feed roller. The torque control of the second drive control means is performed when a force of a predetermined value or more is applied to the separate roller from the feed roller that is in direct contact with the sheet or that is sandwiching the sheet together. The sheet rotates in the sheet conveying direction along with the feed roller, and the torque is controlled so that the sheet rotates in the opposite direction to the sheet conveying direction when a force less than a predetermined value is applied. In the sheet feeding device that separates the sheets one by one and sends out the sheets one by one by returning the excessively fed sheets to the sheet stacking means when a plurality of sheets are fed out in an overlapped manner, the second driving source The DC motor is a DC motor , and the rotation angular velocity calculated from the rotation amount of the second drive source detected by the second encoder and the applied voltage output from the second drive control means to the DC motor are input. a torque estimating means for estimating the torque of the DC motor based on a relational expression between the rotational angular velocity, the applied voltage, and the torque of the DC motor; a sheet double feeding detection means that monitors the estimated value and determines that the sheets are double fed and separation is to be started when the estimated torque value is less than a predetermined value; If it is determined to start the transfer, the target torque of the torque control of the second drive control means is increased .

According to the present invention, it becomes possible to perform torque control of a reverse motor at a lower cost than conventionally.

1 is a cross-sectional view showing a schematic configuration of a sheet conveying device according to an embodiment. FIG. 3 is a block diagram of a control system of a separation motor of the sheet conveyance device. FIG. 3 is a diagram showing an example of a reaction force estimation observer. FIG. 3 is a diagram illustrating a configuration example in which the sheet conveyance device is provided with a sheet double-feed detection means for detecting double-feed of sheets. FIG. 5 is a diagram illustrating the timing at which the sheet double feeding detection means shown in FIG. 4 determines the start of separation due to double feeding of sheets and the completion of sheet separation based on a change in the rotational speed of the separation motor. When the sheet double feeding detection means shown in FIG. 4 monitors the estimated torque value of the separation motor and determines that separation has started due to sheet double feeding, 1 is an example of a schematic diagram of a sheet conveying device that increases the size of a sheet. 7 is a diagram illustrating the timing for judging whether separation of sheets is started due to double feeding from a change in the torque estimated value and whether separation of sheets is completed in the sheet conveying device illustrated in FIG. 6 . FIG. 3 is an explanatory diagram of the leading edge position of a paper that is double fed with the first sheet due to the stoppage of the paper feed motor in an embodiment of the present invention; 12 is a sectional view showing a schematic configuration of a sheet conveying device 1201 in an embodiment of claim 9. FIG. 1 is a cross-sectional view showing a schematic configuration of a sheet conveying device according to an embodiment (in a case where only one controller is used); FIG. 1 is a cross-sectional view showing a schematic configuration of a sheet conveying device according to an embodiment of the present invention (when a single controller is used); FIG. 3 is a diagram illustrating an example of a sheet type input section according to the present embodiment. 1 is a sectional view showing an image forming apparatus as an embodiment of the present invention.

Embodiments of the present invention will be described below. The present invention relates to a sheet feeding device that separates and feeds sheets (storage media such as paper) one by one from a tray loaded with sheets, and a copying machine, a printer, a facsimile machine equipped with the same, or a copying machine, a printer, a facsimile machine, or the like. Regarding image forming apparatuses such as multifunction devices and offset printing machines, in particular, the image forming apparatus is equipped with a feed roller that is rotationally driven to send out the sheet in the sheet conveyance direction, and a separate roller that presses and holds the sheet together with the feed roller. The separate roller is driven by torque control, and when a force of more than a predetermined value is applied from the feed roller that is in direct contact with the sheet or that is sandwiching the sheet together, the separate roller rotates in the sheet conveying direction along with the feed roller to reach the predetermined value. By rotating in the opposite direction to the sheet conveyance direction when a force of less than By doing so, the sheet feeding device and image forming device that separate and feed sheets one by one have the following features. In short, the torque is estimated from the motor rotation speed detection result and the controller output (motor drive voltage) based on the relational expression between the motor rotation speed and applied voltage measured in advance for the DC motor and the DC motor torque. A feature of the present invention is that torque control is performed without a current detection means (sensor) by making control decisions based on the estimated torque and setting a target value. Another feature is that not only the control of the separation motor but also the control of the paper feed motor is adjusted depending on whether or not double feeding occurs, making it easier to prevent double feeding. Therefore, it is possible to realize a technology for improving the paper feeding and separation performance of the sheet feeding device and reducing the deterioration of the characteristics of the component equipment (wear of the reverse roller) at low cost. The features of the present invention described above will be explained in detail using the following drawings.

FIG. 1 is a sectional view showing a schematic configuration of a sheet conveying device 1201 according to this embodiment. In the sheet conveying device 1201, a sheet feeding roller C2 that is a feed roller, a separation roller C1 that is a separate roller, a sheet feeding motor M2, and a separation motor M1 constitute a sheet conveying means. The sheet conveying means sandwiches the sheet between the paper feed roller C2 and the separation roller C1, and conveys the sheet by rotationally driving the paper feed roller C2. The sheet conveying device 1201 further picks up a sheet stacking tray T for stacking sheets, a sheet lifting plate for lifting the sheets stacked on the sheet stacking tray T toward a pickup roller C3, and a rotation drive of a paper feed motor M2. It includes a timing belt that transmits transmission to the roller C3, and a separation motor M1 that rotationally drives the separation roller C1 in a direction opposite to the sheet conveyance direction D1. Furthermore, the sheet conveyance device 1201 includes a sensor (not shown) that detects sheets conveyed in the conveyance direction D, and a separation roller biasing member 103 that biases the separation roller C1 toward the sheet feeding roller C2. The above-mentioned sensor is arranged directly below the axis of the paper feed roller C2 or slightly downstream in the conveyance direction.

With the above configuration, when feeding sheets, the sheet conveying device 1201 raises the sheet lifting plate provided in the sheet stacking tray T to lift the sheets stacked thereon to the highest position. Press the upper sheet against the pickup roller C3. At this time, the sheet lifting plate stops lifting when pressed with a pressure within a predetermined range. A sensor is provided to detect that the uppermost sheet has pressed against the pickup roller C3. When the sheet is not being fed, the sheet lifting plate may be lowered.

In the sheet conveyance device 1201, when the pickup roller C3 is rotationally driven in the sheet conveyance direction D1 with the topmost sheet pressed against the pickup roller C3, the sheet is sent out from the sheet stacking tray T. The pickup roller C3 is rotationally driven by transmitting the rotational drive of the paper feed motor M2, which is a drive source of the paper feed roller C2, via a timing belt. The sheet sent out from the sheet stacking tray T enters a portion (nip portion) where the paper feed roller C2 and the separation roller C1 are pressed against each other. The paper feed roller C2 is rotationally driven by a paper feed motor M2 so as to send out the sheet in the sheet conveyance direction D1. The paper feed roller C2 presses and holds the sheet together with the separation roller C1. A controller 102 drives and controls the position and speed of the paper feed motor M2.

The separation roller C1 is driven by a separation motor M1 via a predetermined driving force transmission means. In this embodiment, a torque limiter is not provided on the separation roller shaft as a predetermined driving force transmission means, and the controller 101 controls the return force of the separation roller C1 using the separation roller motor (separation motor M1). The separation motor M1 rotates the separation roller C1 in the opposite direction to the sheet conveyance direction, but when passing one sheet, it rotates in the sheet conveyance direction (while applying a return force, it also rotates in the direction D2) and separates two sheets. When the above sheets are passed through the nip portion, the separation motor M1 is controlled with a torque that causes it to stop or rotate in reverse (reversely rotate in direction D3).

By rotating in the direction D3, the separating roller C1 functions to return the excessively fed sheets to the sheet stacking tray T when a plurality of overlapping sheets are fed out from the pickup roller C3. This is because the friction between the sheets is smaller than the friction between the separation roller C1 and the sheets. As a result, the sheet conveying means feeds out the sheets one by one. Note that the drive source for the separation roller C1 may be shared with the paper feed motor M2 instead of being installed exclusively as the separation motor M1.

Although a part (spring) is illustrated as the separation roller biasing member 103 which is a means for applying pressure (separation pressure) to press the separation roller C1, which is a reverse roller, against the paper feed roller C2, the means is as follows. In addition to springs, a mechanism that flips up a gear attached to the shaft of the separation roller by a gear connected to a drive source may be used, and a structure similar to that of a conventionally known sheet conveying device may be adopted. .

In the configuration shown in FIG. 1, the sheet conveyance device 1201 rotates in the sheet conveyance direction in contact with a sheet stacking tray T, which is a sheet stacking means for stacking sheets, and the uppermost sheet of the sheets stacked on the sheet stacking means. A pickup roller C3 that is a driven pickup roller, a paper feed roller C2 that is a feed roller that is rotationally driven to feed the sheet in the sheet conveying direction D1, the pickup roller C3, and the paper feed roller C2 are rotationally driven. A paper feed motor M2 that is a first drive source for the paper feed motor M2, a first encoder (not shown) that detects the rotation amount of the paper feed motor M2, and a first drive based on the rotation amount detected by the first encoder. a controller 102 that is a first drive control means that controls the speed or position of the source, a separation roller C1 that is a separation roller that presses and holds the sheet together with the paper feed roller C2, and a controller that rotationally drives the separation roller C1. A separation motor M1 that is a second drive source, a second encoder (not shown) that detects the rotation amount of the separation motor M1, a controller 101 that is a second drive control means that torque controls the separation motor M1, and a A separating roller urging member 103 is provided as a separating pressure applying means for applying pressure (separating pressure) to press the roller C1 against the paper feed roller C2, and the torque control of the second drive control means is performed when the separating roller C1 When a force of more than a predetermined value is applied from the paper feed roller C2 that is in direct contact with the sheet or that is holding the sheet together, the paper feed roller C2 rotates in the same direction D2 as the sheet conveyance direction D1. When a force less than a predetermined value is applied, the torque (returning force) is controlled so that the sheet rotates in the direction D3 opposite to the sheet conveyance direction D1, and as a result of this control, multiple sheets are sent out in an overlapped manner. In this case, the excess sheets are returned to the sheet stacking tray T, which is a sheet stacking means, so that the sheets are separated one by one and sent out. In such a configuration, the separation motor M1, which is the second drive source, is a DC motor, and based on the relational expression between the motor rotation speed and applied voltage measured in advance for the DC motor, and the torque of the DC motor, After calculating the rotational angular velocity from the amount of rotation of the separation motor M1 detected by the second encoder, the torque of the DC motor is estimated based on the voltage applied to the DC motor from the controller 101, which is the second drive control means. A reaction force estimation observer 201 (described later) is provided as a torque estimation means. With this configuration, during paper conveyance (paper feeding), detection of double feeding and control of separation of double fed sheets are performed based on the torque of the motor that drives one of the rollers contributing to conveyance. Torque control can be performed without providing a current detection means (sensor), and therefore, torque control of the reverse motor can be performed at lower cost than conventionally.

FIG. 2 is a block diagram of the control system of the separation motor M1 of the sheet conveyance device 1201. The sheet conveying device 1201 does not detect the current of the motor using a current detection means (sensor), but uses the output of the controller 101 (voltage applied to the motor) and the motor shaft rotation speed measured by the sensor as a reaction force estimation observer 201. is input, the estimated value of the return force to the seat is calculated as the estimated reaction force value, and feedback control is performed. The reaction force estimation observer adopts a conventionally known configuration, for example, as shown in Fig. 3, which inputs the motor applied voltage and motor shaft rotation speed and outputs the estimated value of the reaction torque. can do.

Further, as shown in FIG. 4, the sheet conveying device 1201 may be provided with a sheet double feeding detection unit that detects double feeding of sheets. The sheet double feeding detection means 401 monitors the rotational speed of the separation motor M1, determines whether sheets are being fed in duplicate and starts separation, and when it is determined to start separation, the target of the separation motor M1 is determined. Increase torque. In FIG. 4, the sheet double feeding detection means 401 inputs the rotational speed from the separation motor M1, and if the rotational speed is equal to or higher than a predetermined threshold value and does not change for a certain period of time, the sheet is double fed and the sheet is double fed. The controller 101 instructs the controller 101 to change the target torque.

In this way, in the sheet conveying device 1201 shown in FIG. 1, the amount of rotation (rotational speed) of the separation motor M1, which is the second drive source, is monitored while the sheet is being fed, and if the rotational speed falls below a predetermined value. If it is determined that sheets are being fed in duplicate and separation is to be started, the controller 101 is a second drive control unit. Control is performed to increase the target torque of torque control. With such control, double feeding of sheets can be detected without installing a dedicated double feeding detection sensor. In addition, since the return force is increased only when double feeding occurs, no return force is applied unnecessarily when only one sheet is being fed, which reduces the amount of friction between the separate roller and the sheet. The lifespan of parts can be extended.

FIG. 5 is a diagram illustrating the timing at which the sheet double feeding detection means shown in FIG. 4 determines the start of separation due to double feeding of sheets and the completion of sheet separation based on changes in the rotational speed of the separation motor.

As shown in FIG. 5, in the sheet conveying device 1201, the sheet double feeding detection means 401 detects that the rotation speed of the separation motor M1 exceeds the threshold value V1 after the starting of the separation motor M1 is completed. If speed monitoring is started at time T0 and the rotational speed of separation motor M1 remains constant for a certain period of time without increasing, it is determined that sheets are being double fed at the time T1. and instructs the controller 101 to change the target torque. Then, the controller 101 changes the target torque so that the separation motor M1 rotates in reverse for a certain period of time. Thereafter, the sheet double feeding detection means 401 increases the rotational speed of the separation motor M1, as in the case before the above-mentioned time T1, and the rotational speed exceeds the threshold value V2 for determining that the separation of the sheets has been completed. Then, at time T2, it is determined that the sheet separation is completed, and sheet conveyance is continued.

The threshold value (V1) for determining that separation is to be started due to double feeding of sheets and the threshold value (V2) for determining that sheet separation has been completed may be different values or may be the same. good. In FIG. 5, the separation motor M1 is trying to rotate the separation roller C1 in the opposite direction to the sheet conveyance direction, so when the sheets are fed in duplicate and separation starts, the separation roller decelerates and rotates in the opposite direction. When the separation is completed and the first sheet (upper layer) of paper is rotated again, the separation roller C1 rotates in the conveyance direction.

FIG. 6 shows that the sheet double feeding detection means shown in FIG. 1 is an example of a schematic diagram of a sheet conveying device that increases the target torque of a motor. In FIG. 6, the sheet double feeding detection means 401 inputs the estimated torque value of the separation motor M1 from the controller 101, and if the torque estimate value does not change for a certain period of time over a predetermined threshold value, the sheet double feeding is detected. Therefore, the controller 101 determines to start separating the double-fed sheets and instructs the controller 101 to change the target torque.

In this way, in the sheet conveying device 1201 shown in FIG. 1, the torque (estimated value by the reaction force estimation observer 201, which is a torque estimating means) of the separation motor M1, which is the second drive source, is monitored during sheet feeding. The present invention includes sheet double feeding detection means 401 that determines that sheets are double fed and that separation is to be started when the estimated torque value is less than a predetermined value. In this case, the target torque of the torque control of the controller 101, which is the second drive control means, is increased, so double feeding of sheets can be detected by a method different from that shown in FIG. 4 without installing a dedicated double feeding detection sensor. . In addition, since the return force is increased only when double feeding occurs, no return force is applied unnecessarily when only one sheet is being fed, which reduces the amount of friction between the separate roller and the sheet. The lifespan of parts can be extended.

FIG. 7 is a diagram illustrating the fact that sheets are multi-fed and separation is started based on a change in the estimated torque value, and the timing for determining completion of sheet separation in the sheet conveying apparatus shown in FIG. 6. As shown in FIG. 7, in the sheet conveyance device 1201, the sheet double feed detection means 401 detects that the separation motor M1 is activated after the estimated torque value of the separation motor M1 exceeds the threshold value V1 after the separation motor M1 has been started. Monitoring of the estimated torque value starts at time T0, and if the estimated torque value of the separation motor M1 remains constant without increasing for a certain period of time thereafter, double feeding of sheets occurs at the relevant time T3. It instructs the controller 101 to change the target torque. Then, the controller 101 changes the target torque so that the separation motor M1 rotates in reverse for a certain period of time. After that, the sheet double feeding detection means 401 increases the estimated torque value of the separation motor M1, as in the case before the above-mentioned time T3, and the estimated torque value becomes the threshold value V2 for determining that the sheet separation is completed. When the time T4 is exceeded, it is determined that the sheet separation is completed at that time T4, and sheet conveyance is continued. The fact that the estimated torque of the separation motor M1 does not increase and remains constant is because the reaction force is estimated when the double-fed lower sheet slips against the upper sheet due to the return force from the separation roller C1. This can be determined by utilizing the decrease in the reaction force estimated by the observer, and the timing can be determined to be timing T3 when the sheets are being fed in duplicate and separation is started. The threshold value (V1) for determining that separation is to be started due to double feeding of sheets and the threshold value (V2) for determining that sheet separation has been completed may be different values or may be the same. good.

In the sheet conveying device 1201 shown in FIGS. 4 and 6, when the sheet double feeding detection unit 401 determines that sheets are being fed double and separation is to be started, the target torque is increased until the sheet being conveyed passes. Control may also be performed to leave it as it is. With such control, when the double-fed sheets can be returned to the tray side, the separation rollers follow the sheets and rotate in the sheet conveyance direction. In the sheet conveyance device 1201 shown in FIGS. 4 and 6, when the rotational speed or estimated torque value again exceeds a predetermined value, control is performed to return the target torque level to the original value. However, as an embodiment of claim 4, even if the rotational speed or the estimated torque value exceeds a predetermined value again, the target torque level is controlled so as not to return to the original level, so that the seat becomes heavy again. Even if it is sent, the return operation can be performed quickly.

As shown in FIGS. 5 and 7, the sheet conveying device 1201 according to an embodiment of claims 6 and 7 is configured such that the sheet double feeding detection means 401 detects that the sheets are being fed in duplicate. After determining to start separation, continue to monitor the rotation amount (rotational speed) of the separation motor M1, which is the second drive source, or the torque (estimated value by the torque estimating means) of the separation motor M1, which is the second drive source, When the amount of rotation (rotational speed) of the second drive source or the torque (estimated value by the torque estimation means) of the second drive source exceeds a predetermined value, it is determined that the separation of the sheets is completed, and the second drive source When the sheet double feeding detection means 401 determines that sheets are being fed in duplicate and separation is to be started, the controller 102, which is a first drive control unit, stops driving the paper feed motor M2, which is a first drive source, and detects the sheet weight. When the feed detection means 401 determines that the separation of the sheets is completed, the driving of the first drive source is restarted.

As shown in FIGS. 5 and 7, the sheet conveying device 1201 in an embodiment of claim 8 is configured such that the controller 102, which is the first drive control means, detects when the sheet double feeding detection means 401 detects that sheets are being fed double. When it is determined that separation has started, the drive of the paper feed motor M2, which is the first drive source, is reduced to a predetermined speed, and when the sheet double feed detection means 401 determines that sheet separation has been completed, Control may be performed to return the speed of the first drive source to a normal speed. Although this type of control reduces the effect of preventing double feeding compared to the configurations shown in Figures 4 and 6, it can reduce the delay in paper feeding operations when the double feeding prevention operation is activated, thereby reducing the impact on subsequent systems. can be reduced.

FIG. 8 is an explanatory diagram of the leading edge position of the paper fed double with the first sheet due to the stoppage of the paper feed motor in one embodiment of the invention. As shown in FIG. 8, the controller 101 is a nip formed by the separation roller C1 and the paper feed roller C2, and the position of the transport roller downstream in the transport direction (P1) from the position of the paper feed separation part (P2). If double feeding is detected during this period, the paper feed motor M2 is stopped. As shown in the upper part of FIG. 8, when the paper feed motor is not stopped, the leading edge position 801 of the first sheet progresses over time to the downstream conveyance roller position (P1) in the conveyance direction, while the separation roller C1 causes double feeding. The leading edge position 802 of the lower sheet that is prevented from moving forward with the first sheet to the conveying roller position (P1) downstream in the conveying direction does not change its position even after a certain period of time has elapsed. It turns out that there isn't. On the other hand, when the paper feed motor is stopped for a certain period of time (TT) as shown in the lower part of FIG. There is no attempt to advance to position (P1), and the position has not changed even after a certain period of time has elapsed. That is, by stopping the paper feed motor, the amount of overshooting of the double-fed sheets is suppressed, and the possibility that the double-fed sheets reach the downstream roller pair (transport roller pair) is further suppressed.

FIG. 9 is a sectional view showing a schematic configuration of a sheet conveying device 1201 according to an embodiment of the present invention. In addition to the configuration shown in FIG. 4, FIG. 9 further includes a conveyance roller pair sheet nip determination means 903 that determines whether a sheet is nipped between the conveyance roller pair. In FIG. 9, a pair of conveying rollers (a conveying roller R1 and an opposing roller R2) that press and hold the sheet sent out from the sheet conveying apparatus 1201 between the pair of rollers is shown at the downstream stage of the sheet conveying direction D1 of the sheet conveying apparatus 1201 shown in FIG. ), a transport motor M3 that is a third drive source for rotationally driving the transport roller pair (or transport roller R1), a third encoder (not shown) that detects the amount of rotation of the transport motor M3, A controller 902, which is a third drive control means that controls the position and speed of the motor M3, and a sheet presence/absence detection means 901, such as a sensor that detects the presence or absence of a sheet at the position of the pair of conveyance rollers or a position slightly downstream, control the conveyance. It has conveyance roller pair sheet nipping determination means 903 that determines whether the roller pair has nipped the sheet. In the sheet conveyance device 1201 shown in FIG. 9, after the conveyance roller pair sheet nipping determination unit 903 determines that the sheet is nipped between the conveyance roller pair, the sheet double feed detection unit 401 detects that the sheets are being double fed. When determining that it is the timing to start separation, the controller 902 stops driving the conveyance motor M3, and when the sheet double feed detection means 401 determines that sheet separation has been completed, it resumes driving the conveyance motor M3. With this kind of control, after the first sheet reaches the transport roller pair, when the second and subsequent sheets rush into the part where the feed roller and separation roller that constitute the paper feed separation section are in contact, The same effects as in FIGS. 4 and 6 can also be obtained.

In addition, in the sheet conveyance device 1201 shown in FIG. 9, as an embodiment of claim 9, the conveyance roller pair sheet nipping determination means 903 determines that the sheet double conveyance is carried out after determining that the conveyance roller pair has pinched the sheet. If the detection means determines that the sheets are double fed and separation has started, the controller 902 reduces the drive of the conveyance motor M3 to a predetermined speed, and the sheet double feed detection means 401 determines that separation of the sheets has been completed. If it is determined that this is the case, the speed of the transport motor M3 is returned to the normal speed. With this kind of control, after the first sheet reaches the transport roller pair, when the second and subsequent sheets rush into the part where the feed roller and separation roller that constitute the paper feed separation section are in contact, The same effects as in FIGS. 4 and 6 can also be obtained.

In addition, in the sheet conveyance device 1201 shown in FIG. 9, as an embodiment of claim 10, when the conveyance roller pair sheet nipping determination means 903 determines that the sheet is nipped by the conveyance roller pair, the first drive control means The controller 102 may stop driving the paper feed motor M2, which is the first drive source. With such control, the sheet can be conveyed only by the pair of conveying rollers, and an energy saving effect can be obtained. Note that, as shown in FIGS. 10 and 11, the function of the controller 102 may be included in the controller 101, so that the sheet conveying apparatus 1201 has one controller. Thereby, a more compact sheet conveying device 1201 can be realized.

FIG. 12 is a diagram showing an example of the sheet type input section 1202 according to the present embodiment. The sheet conveyance device 1201 includes a sheet stacking tray 1203, a sheet discharge tray 1204 for discharging sheets, and a sheet type input device 1202 for inputting (selecting) a sheet type. .

The sheet conveying apparatus 1201 shown in the previous figures includes a sheet type input device having a sheet type input section 1202 through which the user can input the sheet type, and according to the sheet type input from the sheet type input device, At least one of the predetermined value of the rotational speed or estimated torque value, the target torque, and the value of the target torque during double feeding may be changeable. With such a configuration, it is possible to set the optimum return force depending on the type (characteristics) of the sheet, and it is possible to improve double feeding prevention performance (separation performance) and reduce the amount of rubbing between the separation roller and the sheet.

FIG. 13 is a sectional view showing an image forming apparatus as an embodiment of the present invention. The illustrated image forming apparatus schematically shows the entire internal mechanism of an example of an electrophotographic tandem indirect transfer color copying machine (hereinafter simply referred to as a copying machine). In the figure, 100 is the main body of the copying machine which is the main body of the image forming apparatus, 200 is the sheet conveyance device on which it is placed, 300 is the scanner attached to the copying machine body 100, and 400 is the automatic document feeder (ADF) further attached thereon. .

The copying machine main body 100 is provided with an endless belt-shaped intermediate transfer member 10 in the center thereof, which is wound around a drive roller 14 and two driven rollers 15 and 16 so that it can be rotated and conveyed clockwise in the figure. Of course, it is also possible to separately wrap the roller around four or more rollers, such as around a roller that adjusts the offset of the intermediate transfer body 10. Although the intermediate transfer body 10 is stretched almost horizontally in the illustrated example, it may be stretched diagonally instead of horizontally.

Further, in the illustrated example, a belt cleaning device 17 for removing residual toner remaining on the intermediate transfer body 10 after image transfer is provided on the left side of one of the driven rollers 15 in the figure.

On the intermediate transfer body 10 stretched horizontally between the driving roller 14 and the driven roller 15, four monochrome image forming means 18 of yellow, cyan, magenta, and black are arranged side by side along the conveying direction. A tandem image forming device 20 is provided. An exposure device 21 is further provided above the tandem image forming device 20.

On the other hand, a secondary transfer device 22 is provided below the spanning area of the intermediate transfer body 10. In the illustrated example, the secondary transfer device 22 is constructed by wrapping a secondary transfer belt 24, which is an endless belt, between two rollers 23, and presses the secondary transfer belt 24, which is an endless belt, onto the intermediate transfer body 10 by pressing it against the other driven roller 16. Transfer the image to a recording medium.

A fixing device 25 is provided beside the secondary transfer device 22 to fix the transferred image on the recording medium. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26, which is an endless belt. In the illustrated example, a part (or all of it) of the intermediate transfer member 10 is provided so as to be inserted below the spanning area of the intermediate transfer member 10 . The secondary transfer device 22 also has a medium conveyance function for conveying the recording medium after image transfer to the fixing device 25 . Of course, a non-contact charger may be arranged as the secondary transfer device 22. However, in the case of such a configuration, it is difficult to also provide this media transport function.

Below the secondary transfer device 22 and the fixing device 25, there is a recording medium reversing device 28 for reversing the recording medium in order to form images on both sides of the recording medium in parallel to the extending direction of the intermediate transfer body 10. Be prepared.

When copying using this copying machine, place the original on the document table 30 of the automatic document feeder 400, or open the automatic document feeder 400 and place the original directly on the contact glass 32 of the scanner 300. Then, close and hold the automatic document feeder 400. Then, when a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the scanner 300 is driven to read the contents of the document. . When an original is placed directly on the contact glass 32, the content of the original is read as is.

When a start switch (not shown) is pressed, a drive motor (not shown) rotates the drive roller 14, which rotates the driven rollers 15 and 16, rotating and transporting the intermediate transfer body 10. At the same time, each monochrome image forming means 18 rotates each image carrier 40 to form a monochrome image of each color (yellow, cyan, magenta, black) on each image carrier 40. Then, as the intermediate transfer body 10 is transported, these monochrome images are primarily transferred and overlapped in sequence to form a composite color image on the intermediate transfer body 10.

On the other hand, after pressing a start switch (not shown), one of the pickup rollers 42 of the sheet conveying device 200 is selected and rotated at an appropriate timing. Then, the recording medium is fed out from one of the sheet stacking trays 44 provided in multiple stages in the paper bank 43. The recording media are separated one by one by separation rollers 45 and put into a paper feed path 46, transported by a conveyance section 47, guided to a paper feed path 48 in the copying machine main body 100, and hit registration rollers 49. Stop. In the case of manual paper feed, the paper feed roller 50 is rotated to feed out the recording medium set on the open manual feed tray 51, separated one by one by the separation roller 52, and placed in the manual paper feed path 53, and then the recording medium is also fed by the registration roller 50. Hit 49 and stop.

Then, the registration rollers 49 are rotated in synchronization with the composite color image on the intermediate transfer body 10, the recording medium is fed between the intermediate transfer body 10 and the secondary transfer device 22, and the intermediate transfer is performed by the secondary transfer device 22. The combined color image on the body 10 is secondarily transferred all at once to form a color image on the recording medium.

The recording medium after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25 . After the transferred image is fixed by applying heat and pressure in the fixing device 25, it is switched by the switching claw 55, discharged by the discharge roller 56, and stacked on the paper discharge tray 57. When forming images on both sides of the recording medium, the recording medium is switched using the switching claw 55 and placed in the recording medium reversing device 28, where it is reversed and guided to the transfer position again. After forming an image on the reverse side, the ejection roller 56 The paper is ejected onto the paper ejection tray 57.

On the other hand, the belt cleaning device 17 removes residual toner remaining on the intermediate transfer body 10 after the image transfer, and prepares the intermediate transfer body 10 for image formation by the tandem image forming device 20 again.

Such an image forming apparatus is equipped with a device that supplies a sheet-like storage medium such as paper, and the sheet conveying device 1201 of the present invention can be applied to the device that supplies the storage medium. Therefore, it is possible to provide an image forming apparatus in which the degree of deterioration of the separation roller is reduced at low cost while maintaining or improving double feeding prevention performance (separation performance).

1201 Sheet transport device T Sheet stacking tray C3 Pickup roller C2 Paper feed roller M2 Paper feed motor 102 Controller C1 Separation roller M1 Separation motor 101 Controller 103 Separation roller biasing member 401 Sheet double feed detection means 901 Sheet presence/absence detection means 902 Controller 903 Conveyance Roller vs. sheet pinching determination means

Japanese Patent Application Publication No. 09-067037 Japanese Patent Application Publication No. 08-217290 Patent No. 4103648 specification

Claims (9)

a sheet loading means for loading sheets;
a pickup roller that is rotationally driven in the sheet conveying direction in contact with the uppermost sheet of the sheets stacked on the sheet stacking means;
a feed roller that is rotationally driven to feed the sheet in the sheet conveying direction;
a first drive source for rotationally driving the pickup roller and the feed roller;
a first encoder that detects the amount of rotation of the first drive source;
a first drive control means for controlling the speed of the first drive source based on the rotation amount detected by the first encoder;
a separate roller that presses and holds the sheet together with the feed roller;
a second drive source for rotationally driving the separate roller;
a second encoder that detects the amount of rotation of the second drive source;
a second drive control means for controlling the torque of the second drive source;
comprising a separation pressure applying means for applying pressure to press the separation roller against the feed roller,
The torque control of the second drive control means is such that when a force of more than a predetermined value is applied to the separate rollers from the feed rollers that are in direct contact with each other or sandwich the sheet together, the separate rollers rotate around the feed rollers and release the sheet. The torque is controlled so that it rotates in the conveying direction and when a force less than a predetermined value is applied, it rotates in the opposite direction to the sheet conveying direction, and by this control, when multiple sheets are sent out in a pile, is a sheet feeding device that separates and feeds sheets one by one by returning excess fed sheets to the sheet stacking means,
The second drive source is a DC motor , and the rotational angular velocity calculated from the rotation amount of the second drive source detected by the second encoder and the applied voltage output from the second drive control means to the DC motor. and torque estimating means for estimating the torque of the DC motor based on a relational expression between the rotational angular velocity, the applied voltage, and the torque of the DC motor .
While feeding the sheets, the estimated value of the torque of the second driving source is monitored, and when the estimated torque value is less than a predetermined value, it is determined that the sheets are being fed in duplicate and separation is to be started. comprising a feed detection means, which increases a target torque for torque control of the second drive control means when it is determined that the sheets are being fed in duplicate and separation is to be started;
A conveying device characterized by: The conveying device according to claim 1 ,
If the sheet double feeding detection means determines that sheets are being fed double and separation is to be started, the target torque is kept high until the sheet being conveyed passes. The conveying device according to claim 1 or 2 ,
Equipped with a sheet type input device that allows the user to input the sheet type,
Conveyance characterized in that at least one of the rotational speed or a predetermined value of the estimated torque value, the target torque, and the value of the target torque during double feeding can be changed depending on the type of sheet input from the sheet type input device. Device. The conveying device according to claim 1 ,
After determining that the sheets are being fed in duplicate and that separation is to be started, the sheet double feeding detection means continues to monitor the estimated value of the torque of the second driving source, and detects that the estimated value of the torque of the second driving source is If the value exceeds a predetermined value, it is determined that the sheet separation has been completed,
The first drive control means stops driving the first drive source when the sheet double feed detection means determines that the sheets are double fed and separation has started, and the sheet double feed detection means stops driving the first drive source. A conveying device characterized in that when it is determined that sheet separation is completed, driving of the first drive source is restarted. The conveying device according to claim 1 ,
The first drive control means reduces the driving of the first drive source to a predetermined speed when the sheet double feeding detection means determines that the sheets are double fed and separation has started, so that the sheet A conveyance device characterized in that when the double feed detection means determines that sheet separation is completed, the speed of the first drive source is returned to a normal speed. The conveying device according to claim 1 ,
A pair of conveyance rollers that press and hold the sheet sent out from the conveyance device between the pair of rollers, a third drive source for rotationally driving the pair of conveyance rollers, and a rotation of the third drive source are provided at a downstream stage of the conveyance device. A third encoder that detects the quantity, a third drive control means that controls the position and speed of the third drive source, and a sheet presence/absence detection means that detects the presence or absence of the sheet at the position of the pair of conveying rollers or at a downstream position. , comprising a conveying roller pair sheet nipping determination means for determining whether the sheet is nipped by the pair of conveying rollers,
If the conveyance roller pair sheet nipping determination means determines that the sheet is nipped by the conveyance roller pair, and then the sheet double feeding detection means determines that sheets are being double fed and separation has started, the third drive A conveying device characterized in that the control means stops driving the third drive source, and resumes driving the third drive source when the sheet double feeding detection means determines that sheet separation has been completed. . The conveying device according to claim 1 ,
A pair of conveyance rollers that press and hold the sheet sent out from the conveyance device between the pair of rollers, a third drive source for rotationally driving the pair of conveyance rollers, and a rotation of the third drive source are provided at a downstream stage of the conveyance device. A third encoder that detects the quantity, a third drive control means that controls the position and speed of the third drive source, and a sheet presence/absence detection means that detects the presence or absence of the sheet at the position of the pair of conveying rollers or at a downstream position. , comprising a conveying roller pair sheet nipping determination means for determining whether the sheet is nipped by the pair of conveying rollers,
If the conveyance roller pair sheet nipping determination means determines that the sheet is nipped by the conveyance roller pair, and then the sheet double feeding detection means determines that sheets are being double fed and separation has started, the third drive The control means reduces the drive of the third drive source to a predetermined speed, and returns the speed of the third drive source to the normal speed when the sheet double feeding detection means determines that sheet separation is completed. A conveying device characterized by: The conveying device according to claim 6 or 7 ,
A conveyance apparatus, wherein when the conveyance roller pair sheet nipping determination means determines that the conveyance roller pair has pinched the sheet, the first drive control means stops driving the first drive source. An image forming apparatus comprising the conveying device according to claim 1 .

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