JP2021187595A - Sheet feeder and image forming system - Google Patents

Abstract

To provide a sheet feeder adapted to positively detect an abnormality in elevational motion of a loading tray or an abnormality of a lower-limit sensor in a shorter time.SOLUTION: A sheet feeder 2 comprises an elevation mechanism 34 that raises and lowers a loading tray 38 between a sheet-feed position and a lower-limit position, an intermediate sensor 63 that detects the loading tray 38 in descending, a lower-limit sensor 61 that detects the loading tray descended to the lower-limit position and a control unit 70. The intermediate sensor is provided at an intermediate position that is between the sheet-feed position and the lower-limit position and longer in distance from the lower-limit position than distance from the sheet-feed position. If neither the lower-limit sensor or the intermediate sensor do not detect the loading tray within a predetermined time from a time point the loading tray starts descending, the control unit controls the elevation mechanism to stop the loading tray.SELECTED DRAWING: Figure 3

Description

The present invention relates to a sheet feeding device for feeding sheets, and more particularly to a sheet feeding device provided with a loading tray capable of loading and lowering sheets. Further, the present invention relates to an image forming system provided with such a sheet feeding device.

Conventionally, an image forming apparatus such as a copying machine or a printer has a built-in or externally equipped sheet feeding device for feeding a sheet to an image forming unit. Generally, a sheet feeding device feeds, for example, a storage that can store a large capacity of several thousand sheets, a loading tray that loads the sheets in the storage, and a top sheet on the loading tray. It has a mechanism. Further, there is known a seat feeding device further provided with an elevating mechanism for raising and lowering a loading tray in a storage (see, for example, Patent Document 1).

In the paper feed device described in Patent Document 1, when a sheet is housed in the paper feed tray, the tray elevating means rotates a motor to raise the paper feed tray to a paper feed position where the sheet can be fed. A tray lower limit sensor that detects that the paper tray is placed at the lower limit position and a tray upper limit sensor that detects that the paper tray is placed at the upper limit position are provided, and a predetermined time has passed since the paper feed tray started to rise. If it is not detected that the upper limit position has been reached, it is determined that the paper tray is abnormal and displayed. In the paper feed device described in Patent Document 1, the maximum predetermined time required to raise the paper feed tray from the lower limit position to the upper limit position by the tray raising / lowering means is set to be relatively long, for example, 10 seconds.

Japanese Unexamined Patent Publication No. 62-88727

However, unlike the conventional sheet feeding device described above, the time required for the loading tray to move up and down between the upper limit position and the lower limit position is set as the abnormality detection time, and the abnormality in the raising and lowering operation of the loading tray is detected based on the abnormality detection time. If this is the case, the following inconveniences may occur. For example, if the lower limit sensor cannot detect the loading tray due to a failure or adhesion / accumulation of paper dust, even if the loading tray reaches or passes the lower limit position, it is loaded until the abnormality detection time is reached. The lowering operation of the tray is continued. Further, even if a foreign substance is present on the bottom surface of the storage and the loading tray cannot reach the lower limit position and cannot be detected by the lower limit sensor, the loading tray lowering operation is continued until the abnormality detection time elapses.

In many elevating mechanisms, for example, as described in Patent Document 1, a loading tray is suspended by a wire, and a winding pulley around which the wire is wound is rotated in both forward and reverse directions by an elevating motor to wind the wire. Or move it up and down by unwinding. Therefore, if the wire is unwound until the abnormality detection time elapses while the loading tray has already reached or passed the lower limit position or has stopped descending due to a foreign object, the wire may be loosened or the wire may be completely wound. It is unwound and rewound in the opposite direction, which may raise the loading tray in some cases. As a result, the loading tray may become inoperable and the lifting mechanism, loading tray, and / or related parts may be damaged.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to be able to reliably detect an abnormality in the lifting operation of the loading tray and an abnormality in the lower limit sensor in a shorter time, and tentatively. It is an object of the present invention to provide a sheet feeding device capable of preventing or reducing damage to an elevating mechanism, a loading tray and / or related parts which may occur even when the lower limit sensor cannot detect the loading tray.

Further, it is an object of the present invention to provide an image forming system provided with such a sheet feeding device.

In order to solve the above problems, the sheet feeding device of the present invention is used.
A loading tray that can be loaded and lowered with seats,
A drive means for raising and lowering the loading tray between the paper feed position and the lower limit position,
A paper feeding means for feeding the top sheet on the loading tray at the paper feeding position, and a paper feeding means.
A lower limit detecting means for detecting the loading tray lowered to the lower limit position,
An intermediate detection means provided between the paper feed position and the lower limit position and at an intermediate position where the distance from the lower limit position is longer than the distance from the paper feed position, and the intermediate detection means for detecting the descending loading tray. When,
With control means,
The control means has both the lower limit detecting means and the intermediate detecting means within a predetermined time set in advance based on the distance between the lower limit position and the intermediate position from the time when the loading tray starts to descend. Controls the drive means to stop the loading tray when does not detect the loading tray.
It is characterized by that.

According to another aspect of the present invention, there is provided an image forming system including the above-described seat feeding device of the present invention and an image forming device for forming an image on a sheet fed from the seat feeding device. To.

According to the sheet feeding device of the present invention, it is possible to reliably detect an abnormality in the lifting operation of the loading tray and an abnormality in the lower limit sensor (lower limit detecting means) in a shorter time, and each part and each part that may be caused by these abnormalities. Damage to parts can be prevented or reduced.

It is an overall block diagram of the image formation system provided with the sheet feeding device which concerns on a preferred embodiment of this invention. (A) is a schematic view showing a state in which the sheet feeding device is separated from the image forming device, and (b) is a schematic view showing a state in which the sheet storage unit is pulled out from the sheet feeding device. It is the schematic which looked at the internal structure of the sheet paper feed device from the front side (the front side of FIG. 1). It is explanatory drawing which shows the elevating mechanism of a seat storage part. It is explanatory drawing which shows the sensor position of an abnormality detecting means. It is a block diagram which shows the control composition of a sheet paper feed device. It is a flow chart which shows the abnormality detection operation of a sheet paper feed device. FIGS. (A) to (c) are explanatory views showing an operation of lowering the loading tray and the sheet in the abnormality detection operation. The figures (a) and (b) are explanatory views showing the lowering operation of the loading tray and the sheet in the abnormality detection operation. The figures (a) and (b) are explanatory views showing the lowering operation of the loading tray and the sheet in the abnormality detection operation. The figures (a) and (b) are explanatory views showing the lowering operation of the loading tray and the sheet in the abnormality detection operation. The figures (a) and (b) are explanatory views showing the pattern 1 of the loading tray ascending operation. FIGS. (A) to (c) are explanatory views showing pattern 2 of the loading tray ascending operation.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows the overall configuration of the image forming system 100 of the present embodiment. The image forming system 100 includes an image forming device 1 and a sheet feeding device 2. The sheet feeding device 2 is connected to the side surface 1a of one of the image forming devices 1 (on the right side in FIG. 1). The image forming apparatus 1 is integrally equipped with a document reading device 3, a document feeding device 4, and a sheet stacking device 5.

(Image forming device)
The image forming apparatus 1 includes a paper feed cassette 6 (in the illustrated embodiment, two paper feed cassettes 6a and 6b) capable of accommodating a predetermined number of sheets (for example, about 100 sheets). The sheet paper feed device 2 is configured to have a relatively large capacity so as to be able to load a larger number of sheets than the paper feed cassettes 6a and 6b.

The image forming apparatus 1 forms an image on a sheet supplied from the paper feed cassettes 6a and 6b or the sheet feeding device 2 based on the image data read from the original sheet by the document reading device 3, and forms an image. The sheets are collected and stored in the sheet collecting device 5. A document sheet can be automatically fed to the document reading device 3 by the document feeding device 4. Here, the sheets handled in the image forming system 100 include small sizes such as A6, B5 and A4 and large size plain papers such as B4 and A3, as well as long sheets other than the standard size, OHP sheets and tracing. It shall include special sheets such as paper and coated paper.

The image forming apparatus 2 is, for example, a copying machine, a printer, a facsimile, or the like, and various known image forming mechanisms can be adopted as long as they can form an image on a sheet, and are installed on a floor surface, for example. To. The image forming apparatus 2 of the illustrated embodiment employs an electrostatic image forming mechanism as an image forming mechanism, but is not limited to this, and is not limited to this, such as an inkjet image forming mechanism, an offset type image forming mechanism, and the like. It is also possible to adopt.

The image forming apparatus 2 shown in FIG. 1 includes a floodlight (laser head or the like) 7, a photosensitive drum 8, a developing device 9, a transfer charger 10, and a fixing roller 11. The sheets stored in the paper cassettes 6a and 6b are sent out by the delivery roller 12 in contact with the uppermost surface thereof, separated one by one by the separation roller pair 13, and the transfer path 15 by the transfer roller pair 14. Is sent to the transfer charger 10. The sheet carried in from the sheet feeding device 2 is similarly fed to the transfer charger 10 through the transport path 15 by the transport roller pair 14.

On the sheet supplied from the paper cassettes 6a and 6b or the sheet paper feed device 2, the toner adhered to the electrostatic latent image (still image) formed by the floodlight 7 on the surface of the photosensitive drum 8 by the developer 9 is applied. It is transferred by the transfer charger 10. The sheet to which the toner is transferred is sent to the fixing roller 11 arranged on the downstream side, the toner on the sheet is heat-fixed, and then the sheet is discharged to the sheet accumulating device 5 by the paper ejection roller pair 16.

A first platen 17 and a second platen 18 made of transparent glass are arranged side by side in the horizontal direction on the upper part of the document reading device 3. The first platen 17 is used for reading a document set by hand, and is formed in a size capable of mounting a document having the maximum size that can be supported. The second platen 18 is used for reading a document fed from the document feeding device 4 and moving at a predetermined speed.

Inside the document reading device 3, a photoelectric conversion means having a first reading carriage 19 and a second reading carriage 20, a condenser lens 21 and a photoelectric conversion element 22 is provided. The first read carriage 19 and the second read carriage 20 are driven by a carriage motor (not shown) and reciprocate below the first platen 17 in the sub-scanning direction. When reading a document placed on the first platen 17, light is emitted from the lamp of the first reading carriage 19 while moving the first reading carriage 19 and the second reading carriage 20. The image of the document on the platen 17 is irradiated, and the reflected light from the document is guided from the mirrors of the first reading carriage 19 and the second reading carriage 20 to the photoelectric conversion element 22 via the condenser lens 21 to be electrically operated. Image data is generated by converting it into a signal.

The document feeding device 4 includes a paper feed tray 23, a sheet transport mechanism 24, and a paper output tray 25. The documents placed on the paper feed tray 23 are conveyed one by one by the sheet transfer mechanism 24, pass over the second platen 18, and are ejected to the output tray 25. When reading a document fed from the document feeding device 4 and passing over the second platen 18, the first reading carriage 19 and the second reading carriage 20 are stopped in advance below the second platen 18. Then, the image data is generated from the document passing over the second platen 18.

(Sheet feeder)
Next, the structure of the sheet feeding device 2 will be described in detail with reference to FIGS. 1 to 3.

The sheet feeding device 2 forms an image by separating a storage 32 for storing a sheet to be supplied to the image forming device 1 and a sheet in the storage 32 into one sheet in a housing 31 accommodating the entire device. A separate paper feeding mechanism 33 for supplying to the device 1 and an elevating mechanism 34 are provided. As shown in FIG. 2A, the housing 31 is attached to a detachable rail 35 housed under the sheet feeding device 2 in order to process jam of the sheet supplied to the image forming apparatus 1, for example. Along the line, it can be separated from the side surface 1a of the image forming apparatus 1.

As shown in FIG. 2B, the storage 32 supplies the sheet from the sheet feeding device 2 to the image forming apparatus 1 by a drawer mechanism 36 provided in the housing 31, for example, in order to replenish the sheet. It is supported so that it can be pulled out in the front direction (front side in FIG. 1) orthogonal to the paper feeding direction. The drawer mechanism 36 is attached to, for example, the slide rails 36a attached to the left and right outer surfaces of the storage 32, and the left and right side surfaces in the housing 31 adjacent to each other so as to slidably support the slide rails 36a. It is composed of a guide rail 36b.

The seat feeding device 2 is provided with an open / close switch 37 near the front side edge of the upper surface of the housing 31. When the user presses the open / close switch 37, the storage 32 is opened by an urging member (not shown) and pushed toward the front side to a position where it can be pulled out. As a result, the user can easily pull out the storage 32 along the guide rail 36b to a position where the seat can be replenished.

The storage 32 has a substantially box-shaped shape with an opening at the top, and a loading tray 38 is provided inside the storage tray 32 so as to be able to move up and down in the vertical direction by an elevating mechanism 34. The loading tray 38 is made of a plate-shaped plate member, and the entire sheet of a predetermined size can be loaded on a substantially flat upper surface thereof. When the storage 32 is pulled out from the housing 31 as described above, the sheet can be loaded and loaded on the loading tray 38 through the upper opening.

In the space for accommodating the loading tray 38 inside the storage 32 (hereinafter referred to as "loading tray accommodating space"), the sheet on the loading tray 38 is sandwiched from both sides in the width direction (direction orthogonal to the paper feeding direction). Left and right side edge restricting members 41 and 42 are provided, and a rear end regulating member 43 located on the rear end (the end farther from the image forming apparatus 1 in the paper feeding direction) side of the sheet on the loading tray 38 is provided. Has been done. In the sheet S on the loading tray 38, the positions of both side ends in the width direction are regulated by the side end regulating members 41 and 42, and the positions of the rear ends in the paper feeding direction are regulated by the rear end regulating members 43. There is.

In the present embodiment, the side edge restricting members 41 and 42 are erected at the bottom of the storage 32 so as to be slidable in the width direction of the seat in conjunction with each other by, for example, a rack and a pinion. The rear end regulating member 43 is erected at the bottom of the storage 32 so as to be slidable in the paper feeding direction. Both the side end regulating members 41 and 42 and the rear end regulating member 43 extend through a window portion (not shown) provided in the loading tray so as not to interfere with the loading tray 38. With such a configuration, the side end regulating members 41, 42 and / or the rear end regulating member 43 are moved on the bottom of the storage 32 according to the size of the sheet loaded on the loading tray 38, and the side thereof. The end position and / or the rear end position can be regulated.

The loading tray 38 is supported by an elevating mechanism 34 so as to be vertically elevated in the storage 32. As shown in FIG. 4, each of the loading trays 38 has four support portions 45 projecting outward in the width direction from positions near the corners on both sides in the width direction. The elevating mechanism 34 includes four wires 46 as a hanging member whose one end is fixed to each support portion 46 of the loading tray 38, four winding pulleys 47 for winding each corresponding wire 46, and each winding. It is composed of a plurality of intermediate pulleys 48 around which a wire 46 extending between the pulley 47 and the corresponding support portion 45 is wound, and an elevating motor M1 for rotationally driving the take-up pulley 47.

Each take-up pulley 47 is fixed on one drive shaft 49 extending along the outer surface of the storage 32 on the rear end side in the paper feeding direction. The drive shaft 49 is rotatably connected to the drive shaft of the elevating motor M1 via a rotation transmission mechanism (not shown). For example, when the elevating motor M1 is driven in the forward direction, the four take-up pulleys 47 rotate simultaneously via the drive shaft 49 to wind the wires 46, respectively, so that the loading tray 38 is pulled up by the four support portions 45 at the same time. It rises while maintaining a nearly horizontal state. When the elevating motor M1 is reversely driven, the four take-up pulleys 47 are rotationally driven in the directions opposite to those at the time of ascending, and each wire 46 is unwound, so that the loading tray 38 maintains a substantially horizontal state due to its own weight. It descends as it is. The elevating mechanism 34 may be any as long as it can elevate and elevate the loading tray 38 while maintaining a substantially horizontal state, and is not limited to that of the present embodiment.

The separate paper feed mechanism 33 separates the feeding roller 51, which comes into contact with the uppermost surface of the sheet loaded on the loading tray 38 and feeds the sheet, and the fed sheet one by one, and conveys them to the image forming apparatus 1. Includes separate transport means. The separation / transfer means is composed of a paper feed roller 52 and a separation roller 53 that presses against the paper feed roller to prevent the supply of the second and subsequent sheets. A transport roller pair 54 for feeding the sheet into the transport path 15 of the image forming apparatus 1 is provided on the downstream side of the separate transport means.

The feeding roller 51 is rotationally driven by the paper feeding motor M2. The feeding roller 51 is configured to be movable between an operating position in contact with the upper surface of the seat and a standby position away from the upper surface of the seat. Similarly, the paper feed roller 52 is driven by the paper feed motor M2 via a plurality of gears and timing belts (not shown) to rotate, and the sheet fed from the loading tray 38 by the feed roller 51 is image-forming device. Supply to 1.

A bracket (not shown) is rotatably supported around the shaft of the paper feed roller 52, the feeding roller 51 is rotatably supported at the tip of the bracket, and the shaft of the paper feed roller 52 by the paper feed motor M2 is supported. The rotation can be configured to be transmitted via a plurality of gears to rotationally drive the feeding roller 51. In this case, for example, the bracket can be rotated around the shaft of the paper feed roller 52 by a solenoid to move the feeding roller 51 between the operating position and the standby position.

A torque limiter (not shown) is attached to the rotation shaft of the separation roller 53. As a result, when two or more sheets are overlapped and niped at the pressure contact portion between the paper feed roller 52 and the separation roller 53, the separation roller 53 stops and blocks the supply of the second and subsequent sheets from the top. It has become. For example, when a plurality of sheets overlap and enter the nip portion of the paper feed roller 52 and the separation roller 53, the driving force of the paper feed roller 52 is transmitted to the highest sheet, while the rotation of the separation roller 53 is stopped. Therefore, slip occurs between the top sheet and the sheet below it, and only the top sheet is sent out separately from the sheet below it. As a matter of course, another member such as a separation pad may be used instead of the separation roller 53.

(Abnormality detection means)
The sheet feeding device 2 includes an abnormality detecting means for detecting a defect in the loading tray 38. The abnormality detecting means includes a lower limit sensor 61, an upper limit sensor 62, and an intermediate sensor 63 in order to detect the positions of the loading tray 38 and the seat in the ascending / descending direction. Further, the abnormality detecting means has an abnormality detection timer for detecting an abnormality in the loading tray 38. Here, the malfunction of the loading tray 38 is, for example, a failure of each sensor for detecting the position of the loading tray 38 and the seat, a failure of the elevating mechanism 34 (elevation motor M1, wire 46, etc.), a failure of the loading tray 38 due to foreign matter, or the like. It refers to an abnormal condition caused by the inability to move up and down.

As shown in FIGS. 1 and 5, the lower limit sensor 61 is arranged at the lower limit position PB in the elevating range of the loading tray 38, and the upper limit sensor 62 is arranged at the upper limit position PT in the elevating range of the loading tray 38. The intermediate sensor 63 is arranged at the intermediate position PM between the lower limit position PB and the upper limit position PT. The distance (L1) from the intermediate position PM to the lower limit position PB is set and arranged so as to be longer than the distance (L2) from the intermediate position PM to the upper limit position PT. In the present embodiment, as the intermediate sensor 63, it is detected that the upper surface of the loading tray 38 or the upper surface of the sheet S mounted on the loading tray 38 has reached the replenishment position for replenishing the sheet in the storage 32. A relay sensor is used.

The abnormality detection timer is set to a time (T) obtained by adding a slightly predetermined time (t2) to the time (t1) required for the loading tray 38 to descend from the intermediate position PM to the lower limit position PB. In the present embodiment, these times set in the abnormality detection timer are drive pulse values for driving the elevating motor M1, and the time is measured by counting the drive pulses.

Further, in the sheet feeding device 2, the uppermost sheet S loaded on the loading tray 38 reaches a height position where the sheet S can be fed toward the image forming apparatus 1 by the separate feeding mechanism 33, that is, the feeding position PU. A top sensor 64 for detecting this is provided. Further, the sheet feeding device 2 has a foreign matter sensor 65 for detecting the presence of foreign matter on the upper surface of the loading tray 38 or the uppermost surface of the sheet S loaded on the loading tray 38, and the upper limit of the storage 32. It has a position above the position PT.

(Air blowing mechanism)
The sheet feeding device 2 is provided with an air blowing mechanism 80 behind the side end regulating member 42 arranged on the back side in FIG. The air blowing mechanism 80 is composed of a first air blower 81 on the image forming apparatus 1 side and a second air blower 82 on the rear end side thereof along the paper feeding direction. The first air blower 81 and the second air blower 82 have blower fans 83 and 84, respectively, and the first air blower 81 is provided with a heater 85 on the upstream side of the blower fan 83.

The side end restricting member 42 is provided higher than the paper feed position PU, and air outlets 86 and 87 of the first air blower 81 and the second air blower 82 are provided at the upper ends thereof, respectively. The lower ends of the air outlets 86 and 87 are below the top sheet so that the upper ends of the air outlets 86 and 87 are located slightly above the top sheet of the loading tray 38 located at the paper feed position PU. It is formed in a size and shape that includes multiple sheets. As a result, when the first air blower 81 and the second air blower 82 are operated and the uppermost sheet of the loading tray 38 is sent out to the image forming apparatus 1 side by the air blown out from the air outlets 86 and 87. , The top sheet can be more easily separated from the sheet below it.

(Double feed prevention mechanism)
In another embodiment, the sheet feeding device 2 has a double feeding prevention mechanism (FIG.) for preventing a plurality of sheets from being fed in an overlapping manner in a transport path from the paper feed roller 52 to the transport roller pair 54. Not shown) can be provided. Such a double feed prevention mechanism can be provided in a transport unit (not shown) connected between the sheet feed device 2 and the image forming device 1. The double feed prevention mechanism is composed of, for example, a sheet sorting mechanism provided in a transport path for transporting a sheet to the image forming apparatus 1, and an escape tray provided below the sheet sorting mechanism. The sheet sorting mechanism includes, for example, a flap member that, when a plurality of sheets are double-fed along the transport path, transports the uppermost sheet as it is, separates the lower sheet, and guides the sheet to the escape tray. be able to.

(Sheet transfer structure)
In still another embodiment, the sheet feeding device 2 includes a sheet transport structure that makes it easy to take out a sheet stopped on the transport path when a jam occurs in the transport path from the paper feed roller 52 to the transport roller pair 54. be able to. Such a sheet transport structure can be provided in a transport unit (not shown) connected between the sheet feed device 2 and the image forming device 1. For example, when a sheet having a bent portion such as an envelope with a flap is oriented and transported on a transport path in a direction in which the opening direction of the bent portion is orthogonal to the transport direction, the bent portion is caught in the transport path and taken out. It may be difficult. The sheet transport structure includes a member in the transport path for preventing the bent portion from being caught.

(Control unit)
The sheet feeding device 2 includes a control unit 70 for controlling its operation. As shown in FIG. 6, the control unit 70 includes a central processing unit (CPU) 71, a ROM 72 which is a read-only memory, and a RAM 73 which is a rewritable memory. The ROM 72 stores in advance the control procedure described later. The RAM 73 is a main storage device used for storing input data, a working storage area, and the like.

The lower limit sensor 61, the upper limit sensor 62, the intermediate sensor 63, the upper surface sensor 64, and the foreign matter sensor 65 are connected to the control unit 70, and the detection signals from each of these sensors are received in real time. ing. Further, the elevating motor M1, the paper feed motor M2, the operation unit 74, and the display unit 75 are connected to the control unit 70, and the CPU 71 controls these operations based on the detection signals from the respective sensors. The display unit 75 displays information such as that the sheet S on the loading tray 38 is in a fully loaded state.

In a normal operating state, when the control unit 70 detects the uppermost surface of the sheet S loaded on the loading tray 38 on which the upper surface sensor 64 is raised, the control unit 70 controls the elevating motor M1 to stop the ascending of the loading tray 38. .. When the lower limit sensor 61 detects the descending loading tray 38, the elevating motor M1 is controlled to stop the descending of the loading tray 38 at the lower limit position PB. When the intermediate sensor 63 detects contact with the descending loading tray 38, the intermediate sensor 63 then descends the loading tray 38 until it is separated from the uppermost surface of the sheet S loaded on the descending loading tray 38. When the intermediate sensor 63 is separated from the uppermost surface of the seat S, the elevating motor M1 is controlled to stop the descent of the loading tray 38.

A timer 76 is connected to the control unit 70 so as to be able to communicate with the CPU 71 in both directions. As the time measured by the timer 76, the time (t1) required for the loading tray 38 to descend from the intermediate position PM to the lower limit position PB in FIG. 5 is after the lower surface of the loading tray 38 comes into contact with the lower surface of the storage 32. Considering the amount of descent of the loading tray 38 per unit time so that the wire 46 is not further unwound from the take-up pulley 47 to cause loosening and is not unwound in the opposite direction after being completely unwound. Set. The timer 76 also functions as an abnormality detection timer for the above-mentioned abnormality detection means.

(Abnormality detection operation)
The abnormality detection operation performed by the abnormality detection means of the sheet feeding device 2 will be described in detail below with reference to FIGS. 7 to 11. First, when the electric power is turned on to the seat feeding device 2, the initial setting is executed. The initial setting is also executed when the user wants to forcibly return the seat feeding device 2 during operation to the initial state. At the time of initial setting, the loading tray 38 descends from the position where it was stopped until then.

This loading tray lowering operation is executed as a default subroutine. Further, in the loading tray lowering operation, when the lock release button 37 of the storage 32 is pressed, the loading tray 38 is lowered until the upper surface of the sheet reaches the replenishment position PS when the storage 32 is pulled out. Will be executed.

The loading tray lowering operation will be described below. First, as the execution of the subroutine in the initial setting or when the open / close switch 37 of the storage 32 is pressed (step ST-B0), the control unit 70 reversely drives the elevating motor M1 (step ST-B1). ). As a result, the loading tray 38 is lowered. Further, at the same time as the reversal of the elevating motor M1, the abnormality detection timer (timer 76) starts timing (step ST-B2).

If the relay sensor 63 is OFF when the elevating motor M1 reverses in step ST-B1, the control unit 70 determines whether the loading tray 38 and the seat are between the upper limit position PT and the replenishment position PS. Alternatively, it is determined that the position is below the replenishment position PS (FIGS. 8 (a) and 9 (a)), and the abnormality detection process 1 is executed (step ST-B3).

On the other hand, if the relay sensor 63 is ON in step ST-B1, the control unit 70 has the loading tray 38 in the replenishment position PS or the sheet in the replenishment position PS below the replenishment position PS (FIG. 10 (a), FIG. 11 (a)) is determined, and the abnormality detection process 2 is executed (step ST-B3).

In the abnormality detection process 1, when the relay sensor 63, the lower limit sensor 61, and the upper limit sensor 62 are in the OFF state (steps ST-B4 to ST-B6) and the abnormality detection timer 76 times out (step ST-B7), the control unit The 70 determines that some trouble has occurred in the loading tray 38 or the components of the sheet feeding device 2 including the respective sensors, and displays an error on the display unit 75 (step ST-B8), and at the same time, the elevating motor M1. (Step ST-B9).

Further, if the relay sensor 63 is turned ON (FIG. 8 (b)) by the time the abnormality detection timer 76 is timed up in step ST-B4 (step ST-B4), the control unit 70 sets the abnormality detection timer 76. After resetting and restarting the abnormality detection timer, the abnormality detection process 2 is executed (step ST-B10).

Next, in step ST-B5, when the lower limit sensor 61 is turned on (FIG. 9 (b)) before the timer times out (step ST-B5), the control unit 70 determines that it is normal, and determines that it is normal. The elevating motor M1 is stopped (step ST-B9).

Further, when the upper limit sensor 62 is turned on in step ST-B6 (step ST-B6), the control unit 70 displays an error on the display unit 75 and at the same time stops the elevating motor M1 (step ST-B9).

In the abnormality detection process 2, as described above, when the loading tray 38 starts descending, the relay sensor 63 is already ON, that is, the loading tray 38 or the sheet on the loading tray 38 has been detected, and the loading tray 38. This is executed when the relay sensor 63 changes from OFF to ON after 38 starts descending.

In the abnormality detection process 2, the relay sensor 63 is in the ON state, and the lower limit sensor 61 and the upper limit sensor 62 are in the OFF state (steps ST-B11 to ST-B13), and the abnormality detection timer 76 is timed up (step ST). -B14), the control unit 70 displays an error on the display unit 75 (step ST-B15), and at the same time, stops the elevating motor M1 (step ST-B9).

On the other hand, before the abnormality detection timer 76 times out in step ST-B14, the relay sensor 63 is turned off in step ST-B11 (FIG. 8 (c) when going through step ST-B4, when going through step ST-B3). In the case of FIG. 10 (b), or when the lower limit sensor 61 is turned on (FIG. 11 (b)) in step ST-B12, the control unit 70 determines that it is normal and stops the elevating motor M1 ( Step ST-B9).

If the relay sensor 63 is turned on, the lower limit sensor 61 is turned off, and the upper limit sensor 62 is turned on (step ST-B13) before the abnormality detection timer 76 times out (step ST-B14), the control unit 70 is activated. , An error is displayed on the display unit 75 (step ST-B15), and at the same time, the elevating motor M1 is stopped (step ST-B9).

As shown in FIGS. 8 (c) and 10 (b), the loading tray 38 is in a state where the upper surface of the sheet reaches the replenishment position PS when the relay sensor 63 is turned off in step ST-B11. When the lower limit sensor 61 is turned on in step ST-B12, the lower limit position PB has been reached.

(Loading tray ascending operation)
In the initial setting, when the above-mentioned loading tray lowering operation is completed and there is no abnormality (error), the control unit 70 rotates the elevating motor M1 in the normal direction to raise the loading tray 38, and the seat on the loading tray 38 is raised. The uppermost surface is moved to the paper feed position PU detected by the upper surface sensor 64. When the top sensor 64 is turned on, the control unit 70 stops the elevating motor M1. As a result, the uppermost surface of the sheet on the loading tray 38 is arranged at the paper feed position PU.

In any case, the control unit 70 is configured to determine an abnormality (error) and stop the elevating motor M1 when the upper limit sensor 62 detects the sheet or the loading tray 38 on the loading tray 38. There is. As a case where the upper limit sensor 62 is turned on in the loading tray lowering operation described above, for example, the following patterns 1 and 2 are assumed.

In pattern 1, as shown in FIG. 12A, when foreign matter A exists between the lower surface of the loading tray 38 and the bottom surface of the seat storage portion 32, the foreign matter A prevents the loading tray 38 from descending to the lower limit position PB. Or, the lower limit sensor 61 has failed and the loading tray 38 that has already reached the lower limit position PB cannot be detected. In pattern 1, the uppermost surface of the sheet on the loading tray 38 is located above the intermediate position PM.

In this case, as the elevating motor M1 continues to rotate, the wire 46 completely unwound from the take-up pulley 47 is rewound, and the loading tray 38 is raised. As shown in FIG. 12B, when the uppermost surface of the loading tray 38 or the sheet on the loading tray 38 reaches the upper limit position PT and is detected by the upper limit sensor 62, the control unit 70 considers this to be abnormal. At the same time as making a judgment and displaying an error on the display unit 75, the elevating motor M1 is stopped.

In pattern 2, as shown in FIG. 13A, foreign matter A exists between the lower surface of the loading tray 38 and the bottom surface of the seat storage portion 32, as in pattern 1, up to the lower limit position PB of the loading tray 38. When the lower limit sensor 61 fails to detect the loading tray 38 which has already reached the lower limit position PB, the uppermost surface of the sheet on the loading tray 38 is the intermediate position PM. It is located below.

In this case, as in pattern 1, as the elevating motor M1 continues to rotate, the wire 46 completely unwound from the take-up pulley 47 is rewound, and in the process of raising the loading tray 38, FIG. 13 ( As shown in b), since the relay sensor 63 is turned on, the timer 76 is reset and the timing is restarted. Also in this case, as shown in FIG. 13C, when the uppermost surface of the loading tray 38 or the sheet on the loading tray 38 reaches the upper limit position PT and is detected by the upper limit sensor 62, the control unit 70 determines this. Is determined to be abnormal, an error is displayed on the display unit 75, and at the same time, the elevating motor M1 is stopped.

The top sensor 64 is controlled so as not to perform the detection operation when the loading tray 38 is lowered, that is, when the elevating motor M1 is reversed. Further, the loading tray 38 is configured so as not to rise when the storage tray 32 is pulled out from the housing 31.

Although the sheet feeding device according to the present invention and the image forming system including the same are described above with reference to the embodiments of the accompanying drawings, the present invention is not limited to the illustrated embodiment.

1 Image forming device 2 Sheet feeding device 32 Storage 33 Separation feeding mechanism 34 Elevating mechanism 36 Pulling mechanism 37 Open / close switch 38 Loading tray 41, 42 Side end regulating member 43 Rear end regulating member 46 Wire 47 Winding pulley 61 Lower limit sensor 62 Upper limit sensor 63 Intermediate sensor 64 Top sensor 65 Foreign matter sensor 70 Control unit 75 Display unit 76 Timer 80 Air blowing mechanism 100 Image formation system M1 Elevating motor M2 Paper feed motor

Claims (9)

A loading tray that can be loaded and lowered with seats,
A drive means for raising and lowering the loading tray between the paper feed position and the lower limit position,
A paper feeding means for feeding the top sheet on the loading tray at the paper feeding position, and a paper feeding means.
A lower limit detecting means for detecting the loading tray lowered to the lower limit position,
An intermediate detection means provided between the paper feed position and the lower limit position and at an intermediate position where the distance from the lower limit position is longer than the distance from the paper feed position, and the intermediate detection means for detecting the descending loading tray. When,
With control means,
The control means has both the lower limit detecting means and the intermediate detecting means within a predetermined time set in advance based on the distance between the lower limit position and the intermediate position from the time when the loading tray starts to descend. The sheet feeding device is characterized in that the driving means is controlled so as to stop the loading tray when the loading tray is not detected. A loading tray that can be loaded and lowered with seats,
A driving means for raising and lowering the loading tray between the upper limit position and the lower limit position,
A paper feeding means for feeding the top sheet from the loading tray, and
An upper limit detecting means for detecting that the uppermost sheet on the loading tray has risen to the upper limit position, and
A lower limit detecting means for detecting the loading tray lowered to the lower limit position,
An intermediate detection means provided between the upper limit position and the lower limit position and at an intermediate position where the distance from the lower limit position is longer than the distance from the upper limit position, and the intermediate detection means for detecting the descending loading tray.
With control means,
The control means has both the lower limit detecting means and the intermediate detecting means within a predetermined time set in advance based on the distance between the lower limit position and the intermediate position from the time when the loading tray starts to descend. The sheet feeding device is characterized in that the driving means is controlled so as to stop the loading tray when the loading tray is not detected. A sheet detecting means for detecting the top sheet on the loading tray in order to move the top sheet to the paper feed position is provided.
The drive means has a drive motor that rotates forward to raise the loading tray and reverses to lower the loading tray.
The control means is such that when the sheet detecting means detects the top-level sheet on the loading tray during the reversal of the driving motor, the driving motor stops and the loading tray is stopped. The sheet feeding device according to claim 1, wherein the sheet feeding device is controlled. The drive means has a drive motor that rotates forward to raise the loading tray and reverses to lower the loading tray.
When the upper limit detecting means detects the uppermost sheet on the loading tray during the reversal of the driving motor, the control means causes the driving means to stop the driving motor and stop the loading tray. The sheet feeding device according to claim 2, wherein the sheet feeding device is controlled. The predetermined time is the time required for the elevating tray to increase the distance between the intermediate position and the lower limit position, plus a predetermined addition time, according to claims 1 to 4. The sheet feeder described in either. When the intermediate detecting means detects the descending loading tray within the predetermined time, the control means continues the descending of the loading tray, and then the intermediate detecting means on the descending loading tray. The sheet feeding device according to any one of claims 1 to 5, wherein when the upper surface of the uppermost sheet is detected, the driving means is controlled so as to raise or stop the loading tray. The control means according to claim 1 to 5, wherein when the lower limit detecting means detects the loading tray within the predetermined time, the control means controls the driving means so as to raise the loading tray. The sheet feeder described in either. The control means is driven so as to stop the loading tray when the lower limit detecting means does not detect the loading tray within the predetermined time from the time when the intermediate detecting means detects the descending loading tray. The sheet feeding device according to any one of claims 1 to 5, wherein the means is controlled. The seat feeding device according to any one of claims 1 to 8.
An image forming system including an image forming device for forming an image on a sheet fed from the sheet feeding device.

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