JP2001072302A - Sheet loading device and image forming device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet loading device whose upward and downward moving mechanism, driving source, etc. are simplified by preventing upward and downward operation of a sheet loading tray under a heavy load. SOLUTION: A sheet loading tray 2 is allowed to move upward and downward when the sheet loading tray 2 is located above a photosensor 13, and only allowed to move downward when the sheet loading tray 2 is located under the photosensor 13. In this way, even if a part of large quantities of sheets are removed from the loading tray 2 loading the sheets, the loading tray 2 under a heavy load is prevented from moving upward so as to regulate upsizing of a upward and downward moving mechanism and a drive source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet stacking apparatus, and more particularly, to stacking a large number of image-formed sheets discharged from an image forming apparatus such as a copying machine, a printer, and a facsimile. The present invention relates to a sheet stacking apparatus having a vertically stackable sheet stacking unit and an image forming apparatus including the same.

[0002]

2. Description of the Related Art Conventionally, in a sheet stacking apparatus for stacking discharged sheets connected to an image forming apparatus or the like,
Sheets on which images are formed by the image forming apparatus are sequentially discharged and conveyed to a sheet stacking apparatus, and are sequentially stacked on a sheet stacking tray in a face-up or face-down state. The sheet stacking apparatus has variously devised in order to improve the alignment of the sheet stacking state.

As one of the methods, there is a method of reducing a sheet drop height at the time of discharging a sheet. The sheet stacking tray is sequentially lowered according to the sheet stacking amount, and the height position of the uppermost sheet of stacking is always set to a predetermined height with respect to the pair of discharge rollers (between the discharge roller and the uppermost sheet). Some devices adjust the height of the loading tray so that the distance is constant.

In order to control the vertical movement of the sheet stacking tray of the above-mentioned apparatus, a sheet height sensor for detecting the height position of the uppermost sheet is provided. When the uppermost sheet height of is higher, the stacking tray elevating mechanism lowers the stacking tray by a predetermined amount.

When the user removes an arbitrary number of sheets on the stacking tray, the height of the uppermost sheet of the stacked sheets is adjusted so that the discharge alignment of the next sheet to be discharged does not deteriorate. The sheet stacking tray is raised by the elevating mechanism until a predetermined height is reached. By performing such control, the stackability and alignment of sheets discharged to the sheet stacking device are improved.

[0006]

However, the above conventional example has the following problems.

(1) Even when the stacking amount of sheets on the stacking tray is large, or when the sheet is almost full, when the user removes the sheet near the uppermost sheet, the stacking tray is raised by the lifting mechanism. It is necessary to keep the uppermost sheet at a predetermined height so as not to deteriorate the alignment of the sheets.

For this reason, as the stacking amount of the sheets increases, the load of the sheets stacked on the sheet stacking tray increases, and it is necessary to raise the sheet stacking tray even when it is near the maximum stacking amount. In order to satisfy the above conditions, there is a problem that, as a sheet stacking device, the size of a drive system, a large power supply, an apparatus, etc. of a lifting / lowering motor for a stacking tray, which supports high torque and high torque, is required.

(2) There is a problem of an increase in the size of the device and an increase in cost due to the problem (1).

(3) In order to take into account the case where a large amount of sheets is loaded, restrictions such as a lifting motor, a driving system, and a power supply occur.
It is necessary to set the lifting speed of the sheet stacking tray relatively slowly. Therefore, it takes a very long time for the sheet stacking tray to move from the lowermost position to the uppermost position. Accordingly, the waiting time of the image forming apparatus is lengthened, and the state in which the next job cannot be received continues for a long time.

According to the present invention, when a large number of sheets are stacked on the sheet stacking means, the operation of the sheet stacking means is improved to increase the size of the apparatus, increase the cost, decrease the speed of lifting and lowering the sheet stacking means, and the like. An object of the present invention is to provide a avoided sheet stacking apparatus and a sheet stacking apparatus including the same.

[0012]

The invention according to claim 1 is
Sheet stacking means capable of stacking sheets to be ejected and capable of moving up and down, elevating means for raising and lowering the sheet stacking means, and sheet height for detecting the height of the uppermost sheet of the sheets on the sheet stacking means The sheet stacking means for detecting the height of the sheet stacking tray; and the sheet stacking means, wherein the sheet stacking means is located above a detection position of the sheet height detecting means. Control means for enabling the sheet stacking means to move up and down, and when the sheet stacking means is below a detection position of the sheet height detecting means, controlling the sheet stacking means to be able to lower only. It is characterized by.

According to a second aspect of the present invention, there is provided a sheet presence / absence detection means for detecting the presence / absence of a sheet on the sheet loading means, and the control means includes a control unit for detecting whether or not the sheet loading means detects the position of the sheet height detection means. And when the sheet presence / absence detection unit detects that there is no sheet, the control unit controls the sheet stacking unit to rise.

According to a third aspect of the present invention, the height of the stacking means is substantially half of the maximum stacking height of the sheets stacked on the sheet stacking means, or substantially half of the maximum load of the sheets. It is characterized by being arranged at a position.

According to a fourth aspect of the present invention, the stacking means height detecting means has a photo sensor and a sensor flag for operating the photo sensor, and the sensor flag is provided on the sheet stacking means. It is characterized by.

According to a fifth aspect of the present invention, there is provided an endless rotating body on which the sheet stacking means is locked so that the sheet stacking means can be moved up and down. It is provided on the rotating body.

[Operation] Based on the above configuration, when the sheet stacking means is located above the stacking means height detecting means, the sheet stacking means can be moved up and down, and the sheets are stacked according to the stacking of the discharged sheets. When the stacking unit is lowered and a part of the sheet on the sheet stacking unit is removed, the sheet stacking unit is raised until the uppermost sheet reaches a predetermined height.

When the sheet stacking means is located below the height detecting means of the stacking means, the sheet stacking means can only be lowered. Even if a part of the sheet on the sheet stacking means is removed, the sheet stacking means does not rise.
As a result, the rise of the sheet stacking means on which a large number of sheets are stacked is suppressed. When all the sheets on the sheet stacking unit have been removed, the sheet stacking unit moves up to the sheet stacking position. The ascending of the sheet stacking means from the lowest position is performed in a state where there is no sheet, so that the ascending speed is sufficiently increased.

[0019]

First Embodiment First, an example of an image forming apparatus main body (copier main body) to which a sheet stacking apparatus according to the present invention can be connected will be described with reference to FIG.

An image forming apparatus main body (copier main body) 900 includes a platen glass 906 as a document placing table, a light source 9
07, a lens system 908, a paper feeding unit 909, an image forming unit (image forming means) 902, an automatic document feeder 100 for feeding a document D to a platen glass 906, and an image-formed sheet discharged from the copying machine main body. A sheet stacking device 1 for stacking P is provided.

A paper supply unit 909 stores cassettes P for recording and is detachably attached to the main body 900 of the apparatus 900.
1 and the deck 913 arranged on the pedestal 912
have. An image forming unit (image forming unit) 902 includes a cylindrical photosensitive drum 914 and a developing device 91 around the photosensitive drum 914.
5, a transfer charger 916, a separation charger 917, a cleaner 918, a primary charger 919, and the like. On the downstream side of the image forming unit 902, a transport device 920,
A fixing device 904, a discharge roller pair 905, and the like are provided.

The operation of the image forming apparatus main body will be described.

When a paper feed signal is output from a control device (control means) 930 provided on the apparatus main body 900 side, the sheet P is sent from the cassette 910, 911 or the deck 913.
Is fed. On the other hand, light reflected from the light source 907 on the original D placed on the platen glass 906 is reflected on the photosensitive drum 914 via the lens system 908. The photosensitive drum 914 has a primary charger 9 in advance.
The electrostatic latent image is charged by light 19 and is irradiated with light to form an electrostatic latent image, and then the electrostatic latent image is developed by a developing unit 915 to form a toner image.

The sheet P fed from the sheet feeding unit 909 is
The skew is corrected by the registration rollers 901, and the skew is sent to the image forming unit 902 at the same timing. In the image forming unit 902, the toner image on the photosensitive drum 914 is transferred to the fed sheet P by the transfer charger 916, and the sheet P on which the toner image has been transferred is placed on the separation charger 91.
7, is charged to a polarity opposite to that of the transfer charger 916,
It is separated from the photosensitive drum 914.

Then, the separated sheet P is conveyed to the fixing device 904 by the conveying device 920, and
04, the transferred image is permanently fixed. The sheet P on which the image has been fixed is discharged to a discharge roller pair (sheet discharge means) 90.
5 is discharged from the apparatus main body 900.

In this manner, an image is formed on the sheet P fed from the sheet feeding unit 909, and the sheet P is discharged from the apparatus main body 900.

FIG. 1 is a perspective view of a sheet stacking apparatus which best illustrates the features of the present invention, and FIG. 2 is a side view of the sheet stacking apparatus.

1 and 2, reference numeral 1 denotes a sheet stacking apparatus 1 which receives a sheet discharged from the image forming apparatus main body 900 at a predetermined conveying speed and sequentially stacks the sheets, and P denotes an image forming apparatus main body 930. 2, a sheet stacking tray of the sheet discharging device 1, an entrance guide portion 3 for receiving the sheet P conveyed from the image forming apparatus main body 930, and 4, discharging the sheet P to the sheet stacking tray 2. A pair of paper discharge rollers 5 are a sheet height sensor flag (sheet height detection means) for detecting the height of the uppermost sheet on the sheet stacking tray 2, and shield a light sensor (not shown) from light. Then, the position of the uppermost sheet is detected.

Reference numeral 6 denotes a pulley 6 for driving a belt (endless rotating body) 7, which is disposed in front of and behind the sheet stacking device 1 with a width across a sheet. Reference numeral 7 denotes a belt, and 8 denotes a drive unit for driving the pulley 6, which is configured to be able to change the moving direction of the belt 7 by forward / reverse rotation of a drive system. 9
Reference numeral denotes a pulley for holding the tension of the belt 7, and is arranged with a width across the sheets before and after the sheet stacking device 1, similarly to the pulley 6.

An elevating mechanism (elevating means) 30 for elevating and lowering the sheet stacking tray 2 is constituted by the pulley 6, the belt 7, the driving unit 8, and the like.

Reference numeral 10 denotes an elevating roller for maintaining the tray angle when the sheet stacking tray 2 is raised and lowered, and is disposed on a side surface of the sheet stacking tray 2 at a predetermined distance. Also,
The elevating roller 10 is similarly provided on the side surface of the sheet stacking tray 2 on the opposing surface portion across the sheet. 11 is provided with a parallel portion so as to sandwich the elevating roller 10,
This is a lifting guide that guides the lifting direction of the lifting roller. The elevating guide 11 is also received by an opposing portion sandwiching the sheet, and has a function of smoothly guiding the elevating of the sheet stacking tray 2.

Reference numeral 12 denotes a sensor flag provided on the side surface of the sheet stacking tray 2, and reference numeral 13 denotes a photosensor (stacking means height detecting means) 1 for detecting the sensor flag 12.
3, the sheet stacking tray 2 is disposed at a predetermined position where it can be detected that the sheet stacking tray 2 has reached a predetermined height.

Reference numeral 14 denotes a belt fixing portion provided upstream of the sheet stacking tray 2 in the sheet conveying direction and connected to both the front and rear of the belt 7. Reference numeral 15 denotes a sheet presence / absence sensor (sheet presence / absence detection means) 15 provided on the sheet stacking surface of the sheet stacking tray 2, which can detect that the sheet P is on the sheet stacking tray 2. FIG. 5 is a drawing showing two sheet stacking trays, and is a drawing showing each configuration in an easily understandable manner.

The operation of the sheet stacking apparatus of the present invention having the above configuration will be described below.

When the power is turned on, the sheet stacking apparatus 1 first checks whether the sheet height sensor flag 5 of the uppermost sheet has detected the sheet height. When the sheet height is detected, the sheet can be discharged and stacked without raising and lowering the sheet stacking tray 2. If the sheet height is not detected by the sheet height sensor flag 5, the sheet presence / absence sensor 15 detects whether or not sheets are stacked on the sheet stacking tray 2.

When it is detected that there is no sheet P on the sheet stacking tray, the lifting motor in the drive system 8 is driven to rotate in the direction in which the sheet stacking tray 2 rises, and the pulley 6 is turned.
As a result, the belt 7 starts lifting the sheet stacking tray 2 upward. Since the sheet P is not stacked on the sheet stacking tray 2, the sheets are not stacked on the sheet stacking tray 2 until the sheet stacking tray 2 is detected by the sheet height sensor flag 5. Ascend to the home position where there is no stop.

Next, when the sheet P is conveyed from the image forming apparatus main body 900, the leading end of the sheet P is guided by the entrance guide 3, and the sheet P is guided to the sheet discharge roller pair 4.
The sheet P is sequentially discharged onto the sheet stacking tray 2 by the roller pair 4. When the sheet height sensor flag 5 detects that a certain or more sheet P is stacked on the sheet stacking tray 2, the sheet stacking tray 2
It is lowered by a predetermined amount by the drive system 8. As described above, the sheets P are successively conveyed from the image forming apparatus main body 900 and the sheet stacking apparatus 1 repeats the above-described sequence to transfer the sheets P to the sheet stacking tray 2.
Loading on top.

Next, it is assumed that the operator extracts only a necessary number of sheets from the sheet bundle stacked on the sheet stacking tray 2. The sheet removal is detected by the sheet height sensor flag 5. In the sheet stacking apparatus 1, the sheet P on the sheet stacking tray 2 is removed from the image forming apparatus main body 900.
A signal is sent to stop the conveyance of the sheet from 0. The sheet stacking apparatus 1 performs the following while the image forming apparatus main body 900 stops conveying the sheet.

(1) In the sheet loading state shown in FIG.
When the sensor flag 12 of the sheet stacking tray 2 is not detected by the photo sensor 13, that is, when the sheet stacking amount on the sheet stacking tray 2 is small, the lower position of the sheet stacking tray 2 indicates that the photo sensor 13 If the height is just before cutting with the sheet stacker (sheet loading tray 2
Is higher than the photosensor 13), the driving system 8 rotates in the direction to raise the sheet stacking tray 2, and the uppermost sheet surface of the stacked sheets P becomes the predetermined height. Is raised until it is detected by the seat height sensor 5.

When the position of the sensor flag 12 of the sheet stacking tray 2 is at the height position before the photo sensor 13 detects the same, the operation is the same as the above-described operation. That is, in the “upward / downward range” shown in FIG. 3, if the stacked sheets are removed during the sheet stacking, the sheet stacking tray 2 can be raised to a predetermined height by the drive system 8.

(2) In the sheet loaded state shown in FIG.
After the sensor flag 12 on the sheet stacking tray 2 is detected by the photo sensor 13 (when the sheet stacking tray 2 is below the photo sensor 13), that is, when the sheets on the sheet stacking tray 2 Indicates that there are many.

In this state, when the stacked sheets are removed from the sheet stacking tray 2 from above, it is detected by the sheet height sensor 5 that the sheets have been removed. On the other hand, the conveyance of the sheet is stopped.

Sensor flag 12 of sheet loading tray 2
However, even if the sheet P on the sheet stacking tray 2 is removed after being detected by passing through the photo sensor 13 when descending, the drive system 8 does not operate. In other words, after the sensor flag 12 of the sheet stacking tray 2 has passed below the photosensor 13 and is detected, even if it is detected that the sheet P on the sheet stacking tray 2 has been 2 is not raised. Since a large amount of sheets P are stacked on the sheet stacking tray 2, the sheet stacking apparatus 1 is kept stopped in the above state.

In order to cancel the above state, it is necessary to remove all the sheets on the sheet stacking tray 2. When the sheet presence sensor 15 detects that all the sheets P on the sheet stacking tray 2 have been removed, the drive system 8 starts driving the sheet stacking tray 2 so that the sheet stacking tray 2 is raised. When the sheet height sensor 5 detects that the sheet stacking tray 2 has risen to a predetermined height, the drive system 8
The lifting of the sheet stacking tray 2 is stopped, and the sheet stacking device 1 is stopped.
Becomes ready. Then, a signal indicating that a sheet from the image forming apparatus can be received is transmitted to the image forming apparatus main body 900.
Send to

When sheets are continuously discharged onto the sheet stacking tray 2 and the sheets are fully loaded,
A full loading state is detected by a full loading position detection sensor (not shown) of the sheet stacking tray 2, and a full loading signal is output to the image forming apparatus main body 900 to stop the conveyance of the sheet P. Then, the user is notified of the removal of the sheet P.
The sheet presence sensor 1 indicates that all the sheets P have been removed.
When the detection is made at 5, the sheet stacking tray 2 is raised, and the sheet stacking apparatus 1 becomes ready, as in (2) described above.

The above operation is controlled by a control device (control means) 930 of the image forming apparatus main body 900. In addition,
A control device may be provided on the sheet stacking device 1 side, and control may be performed while communicating with the control device 930.

<Embodiment 2> FIGS. 6 and 7 show Embodiment 2 of the present invention, and the configuration thereof will be described below. 6 and 7, components having the same reference numerals as those in the first embodiment are components having the same functions. 22
Is a sensor flag provided on the belt 7, and a photo sensor (loading means height detecting means) 23 for detecting the position of the sensor flag 22 is provided with a load of about half of the maximum loading capacity of the sheet loading tray 2. It is arranged at a corresponding position (that is, a position approximately half of the maximum movement range of the sheet stacking tray 2).

With the above configuration, the same operation as that described in the first embodiment can be performed. Further, as compared with the above-described embodiment, the provision of the sensor flag 22 on the belt 7 allows the position of the sheet stacking tray 2 to be accurately defined. In other words, it is possible to reduce the fluctuation of the sensor flag position due to the vertical flapping of the sheet stacking tray 2 or the change in the stacking amount of the sheets P (removal of the sheet by the user). As a result, it is possible to stably detect the height position of the sheet stacking tray 2 under control, and to stably move the sheet stacking tray 2 up and down.

According to the first and second embodiments, the lifting force required to move the sheet stacking tray 2 up and down can be made very small as compared with the conventional sheet discharging device. It is possible to simplify the elevating motor and power supply of the section 8. Thereby, conventionally, a large amount of sheets P
As in the sheet stacking apparatus 1 for stacking sheets, it is possible to avoid an increase in the size and cost of the apparatus due to an increase in the number of sheets that can be stacked. The same sheet tray elevating mechanism can be used.

The sheet stacking device connected to the main body of the image forming apparatus has a low connection rate and requires a sheet stacking device having a different discharge capacity. It is possible to use a common unit, thereby improving the reliability and cost productivity of the device and increasing the efficiency of development.

[0051]

As described above, according to the present invention,
When the sheet stacking unit is above the stacking unit height detecting unit, the sheet stacking unit can be moved up and down, and when the sheet stacking unit is below the stacking unit height detecting unit, the sheet The loading means can only be lowered,
When a small number of sheets are stacked on the sheet stacking unit, when the stacked sheet is removed, the sheet stacking unit is raised to a predetermined position, and when a large amount of sheets are stacked on the sheet stacking unit, When the stacked sheets are removed, the lifting of the sheet stacking means is prevented, so that the lifting operation of the sheet stacking means having a large load can be prevented. This makes it possible to simplify the lifting mechanism, the lifting motor, the power supply, and the like.

When all the sheets on the sheet stacking means have been removed, the sheet stacking means can be moved up to the sheet stacking position. By performing the operation in the state, the lifting speed of the sheet stacking unit can be sufficiently increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sheet stacking apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view of the sheet stacking device.

FIG. 3 is an operation diagram of the sheet stacking device.

FIG. 4 is an operation diagram of the sheet stacking device.

FIG. 5 is a perspective view of a sheet stacking tray.

FIG. 6 is a vertical side view of a sheet stacking apparatus according to a second embodiment of the present invention.

FIG. 7 is a partial perspective view of the sheet stacking device.

FIG. 8 is a longitudinal sectional front view of an image forming apparatus to which the sheet stacking apparatus of the present invention can be applied.

[Explanation of symbols]

P sheet 1 sheet stacking device 2 sheet stacking tray (sheet stacking means) 5 sheet height sensor flag (sheet height detecting means) 7 belt (endless rotating body) 12 sensor flag of stacking means height detecting means 13 photo sensor (stacking) Means height detecting means) 15 sheet presence / absence sensor flag (sheet presence / absence detecting means) 22 sensor flag of stacking means height detecting means 23 photo sensor (stacking means height detecting means) 30 elevating mechanism 900 image forming apparatus main body 902 image forming section (Image Forming Means) 905 Discharge Roller Pair (Discharge Means) 930 Control Device (Control Means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayoshi Fukatsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Ogata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Tomoyuki Araki 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H072 AA26 FB01 FB09 3F054 AA01 AC02 AC03 AC05 BA02 BD02 CA11 CA16 CA40

Claims (6)

[Claims] 1. A sheet to be discharged can be stacked,
A vertically movable sheet stacking unit; an elevating unit for raising and lowering the sheet stacking unit; a sheet height detecting unit for detecting a height of an uppermost sheet of sheets on the sheet stacking unit; and a height of the sheet stacking tray When the sheet stacking means is above the detection position of the sheet height detecting means, the sheet stacking means can be moved up and down, and the sheet stacking is performed. When the means is below the detection position of the sheet height detecting means, the sheet stacking apparatus comprises: control means for controlling the sheet stacking means to be able to lower only. 2. The apparatus according to claim 1, further comprising a sheet presence / absence detection unit configured to detect presence / absence of a sheet on the sheet stacking unit, wherein the control unit is configured to position the sheet stacking unit below a detection position of the sheet height detection unit. And
2. The sheet stacking apparatus according to claim 1, wherein when the sheet presence detecting unit detects that there is no sheet, the sheet stacking unit is controlled to move up. 3. The method according to claim 1, wherein the stacking unit height detecting unit is disposed at a position that is substantially half of a maximum stacking height of the sheets stacked on the sheet stacking unit, or a position that is substantially half of a maximum load of the sheets. The sheet stacking device according to claim 1, wherein 4. The sheet stacking means according to claim 1, wherein said stacking means height detecting means has a photo sensor and a sensor flag for operating said photo sensor, said sensor flag being provided on said sheet stacking means. 4. The sheet stacking apparatus according to any one of 1 to 3, above. 5. An endless rotating body in which the sheet stacking means is locked so that the sheet stacking means can be moved up and down, and a sensor flag of the stacking means height detecting means is provided on the endless rotating body. The sheet stacking apparatus according to claim 4, wherein 6. A sheet stacking device according to claim 1, an image forming unit for forming an image on a sheet based on image information, and a sheet stacking device for forming an image on the sheet by the image forming unit. Discharge means for discharging to
An image forming apparatus comprising: