JPH07315637A - Sheet feed device and image forming device - Google Patents

Abstract

PURPOSE:To provide a sheet feed device which can correct the skew of a sheet by a simple formation. CONSTITUTION:Feeding means 3, 4 are severally arranged in a plurality of sheet loading means 5, 6 for loading sheets. The feeding means 3, 4 are selectively coupled with a motor through a mechanical changing over means, and feed out the sheet from corresponding sheet loading means 5, 6. The sheet is carried to a register roller 1 through a common carrier route 19. A sheet feed sensor 2 for detecting the sheet in the carrier route 19 is arranged in the common carrier route 19. The sheet feed sensor 2 outputs a detecting signal to a control means. The control means controls the functioning time of the feeding means 3, 4 and of the sheet feed sensor 2 according to the time from the beginning of the functioning of the feeding means 3,4 to the detection made by the sheet feed sensor 2 of the sheet. Thus a desired loop can be formed in the sheet on this side of the register roller 1 for preventing the skew of the sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device having a plurality of sheet stacking means and configured to selectively feed sheets from the sheet stacking means by a feeding means, and the sheet feeding device. The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, which is provided with a feeding device.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, as shown in FIG. 5, in order to prevent a fed sheet from being conveyed to a copying position while being skewed, a registration is performed midway along the conveyance path. The roller 21 is provided, and the leading end of the sheet S is abutted against the registration roller 21 to form a loop on the sheet S. This corrects the skew of the sheet S, but if the loop of the sheet S becomes larger than necessary, it may cause the sheet S to be folded. Therefore, it is preferable that the loop amount of the sheet S is as small as possible.

It has also been found that the skew of the sheet occurs largely in the shape of the conveying path between the sheet feeding roller 22 as the feeding means and the registration roller 21.

Therefore, conventionally, each sheet stacking means 23
By providing an electric sheet detecting means (not shown) on the sheet, the control means detects from which sheet stacking means 23 the sheet has been supplied, and thus the sheet stacking means in which the amount of skewed sheets is large. The loop of the sheet S is made large at the time of feeding from 23, and the loop of the sheet S is made small at the time of feeding from the sheet stacking unit in which the amount of skew generation is small.

[0005]

However, in the above-mentioned conventional example, it is necessary to provide one sheet detecting means for each sheet stacking means 23, the circuit configuration of the control means becomes complicated, and the sheet feeding device. As a result, the cost of the image forming apparatus becomes high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sheet feeding device capable of correcting skew of a sheet with a simple structure and an image forming apparatus equipped with the sheet feeding device.

[0007]

A sheet feeding device of the present invention comprises a plurality of sheet stacking means (5, 6) for stacking sheets (10, 11) and the plurality of sheet stacking means (5, 6).
Of the plurality of feeding means (3, 4), which are respectively arranged in the sheet feeding means (5, 6) and feed the sheets (10, 11) from the sheet stacking means (5, 6) to the sheet conveying path side. A mechanical switching means (16) for selectively connecting any one of them with the drive source (14), and a sheet (10) fed from the feeding means (3, 4) selected by the mechanical switching means (16). , 11) to form a desired loop, and a common conveyance path (1) connecting the loop forming means (1) and the plurality of sheet stacking means (5, 6).
9), which detects the sheet in the conveying path (19), and the loop forming means (1) and the sheet feeding means based on the detection signal from the sheet detecting means (2). Control means (1) for controlling the operation of the sending means (3, 4)
2), and a sheet feeding device comprising:

Further, in the sheet feeding apparatus of the present invention, the control means (12) causes the sheet detecting means (2) to move the sheet (10, 11) from the start of operation of the feeding means (3, 4). The feeding means (3, 4) according to the time until detection
And the operation time of the loop forming means (1) is controlled.

Further, the image forming apparatus of the present invention comprises the sheet feeding device (A) and an image forming means (5) for forming a desired image on the sheet fed from the sheet feeding device (A).
4) and are provided.

[0010]

The desired sheet stacking means is selected from the plurality of sheet stacking means (5, 6) by the mechanical switching means (14), and the sheets (10, 10) fed from the sheet stacking means are selected.
11) is detected by the detection means (2). The detection signal output from the detection means (2) is input to the control means (12), and the control means (12) controls the operations of the loop forming means (1) and the paper feeding means (3, 4). do it,
Form the desired loops in the sheet to prevent skewing of the sheet.

The reference numerals in the above parentheses are for comparison with the drawings, and do not limit the structure of the present invention.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is a sheet feeding device A showing a first embodiment of the present invention, and FIG. 2 is a control block diagram of the sheet feeding device A. The sheet feeding device A used in the copying machine will be described below as an example.

In these drawings, the sheet feeding device A
Has a manual feed tray 6 and a cassette 5 as sheet stacking means for stacking sheets. Of these, the manual feed tray 6 is provided with a manual feed roller 3 as a feeding unit that feeds the sheet 11 to the transport path 17 side. On the other hand, the cassette 5 includes a cassette roller 4 that sends the sheet 10 to the side of the transport path 18. The transport path 17 is composed of transport guide plates 8 ₁ and 8 ₂ . In addition, the transport path 18 is
It is composed of transport guide plates 9 ₁ and 9 ₂ . Further, the transport path 19 is composed of the transport guide plate 7.

The sheet 11 of the manual feed tray 6 is
It is conveyed to the registration roller 1 via the conveyance path 17 and the conveyance path 19 shared with the cassette 5 side. Further, the sheet 10 of the cassette 5 is conveyed to the registration roller 1 via the conveyance path 18 and the conveyance path 19.

The registration roller 1 is normally stopped, temporarily stops the sheet sent from the manual feed roller 3 or the cassette roller 4, and forms a loop on the sheet, and functions as a loop forming means. Then, in the transport path 19 on the upstream side of the registration roller 1,
A sheet feeding sensor 2 as a sheet detecting unit is installed. The paper feed sensor 2 is a reflection type photo sensor, detects that a sheet is conveyed through the conveyance path 19, and inputs the detection signal to the CPU 12 as a control unit.

The CPU 12 controls the entire copying machine and has a timer inside. This CP
In U12, the operator who makes the copy sets the copy switch 13 to O
When the answer is N, a control signal is appropriately output to the paper feed clutch 15 to control the operation of the paper feed clutch 15 to be turned on / off.

The paper feed clutch 15 connects the motor 14 as a drive source of the copying machine and the mechanical switching means 16 to disconnect / connect the power transmission based on the control signal of the CPU 12 as described above. The paper feed clutch 15 transmits power from the motor 14 to the mechanical switching means 16 in the ON state, and the OF
In the F state, the power transmission from the motor 14 to the mechanical switching means 16 is cut off.

The mechanical switching means 16 is connected to the manual feed roller 3 and the cassette roller 4, and selectively transmits the power of the motor 14 transmitted through the paper feed clutch 15 to either one of the rollers 3 and 4. It is for doing. The mechanical switching means 16 transmits power to either the manual feed roller 3 or the cassette roller 4 by a copy user operating a switching lever (not shown).

Further, although not shown, in the present embodiment, the length of the conveyance path from the registration roller 1 to the paper feed sensor 2 is 30 mm, and the paper feed sensor 2 to the hand feed roller 3 are provided.
Is 60 mm, the conveyance path length from the paper feed sensor 2 to the cassette paper feed roller 4 is 180 mm, and the sheet conveyance speed is 60 mm / sec.

Next, in the above-mentioned structure, an operating state when the operator supplies sheets from the cassette 5 to perform a copying operation will be described with reference to FIG.

The operator (the person who makes the copy) operates a switching lever (not shown) of the mechanical switching means 16 so that the driving force of the motor 14 is transmitted to the cassette roller 4,
Press the copy switch 13. When the copy switch 13 is pressed, a copy start signal is input from the copy switch 13 to the CPU 12.

The CPU 12 sets each part inside the copying machine (not shown) in a copy-ready state and turns on the paper feed clutch 15.
The driving force of the motor 14 is transmitted to the cassette roller 4 by outputting the N signal, and at the same time, the CPU 1
2 Start the internal timer.

The cassette roller 4 starts to rotate when a driving force is supplied from the motor 15, and starts to feed the uppermost sheet of the cassette 5 along the conveyance path 18 and the conveyance guide 7. At this time, as described above, the sheet conveying speed is 6
0 mm / sec, and the conveyance path length from the cassette paper feed roller 4 to the paper feed sensor 2 is 180 mm.
The paper feed sensor 2 detects the sheet 3 seconds after the paper feed clutch 15 is turned on. And CPU
12 can count the 3 seconds by the internal timer started at the same time when the paper feed clutch 15 is turned on, and determines that the sheet 10 has been sent out from the cassette 5.

In the present embodiment, the sheet feeding from the cassette 5 is longer than the sheet feeding from the manual feed tray 6 and is curved, so that there is a high possibility that skew will occur. In addition, since the amount of skew generated is large, it is necessary to make the loop large. Therefore, CP
After the leading edge of the sheet hits the registration roller 1, U12 continues to turn on the sheet feeding clutch 15 for 0.2 sec, thereby forming a large loop in the sheet and correcting skew of the sheet. After that, the CPU 12 operates the registration rollers 1 to convey the sheet 10 to the image forming unit side (not shown).

Next, a case where the operator supplies a sheet from the manual feed tray 6 to perform a copying operation will be described with reference to FIG.

The operator operates a switching lever (not shown) of the mechanical switching means 16 so that the driving force of the motor 14 is transmitted to the manual feed roller 3, and then the copy switch 13 is operated.
push. When the copy switch 13 is pressed, a copy start signal is input from the copy switch 13 to the CPU 12.

The CPU 12 makes each part inside the copying machine (not shown) ready for copying, outputs a signal for turning on the paper feed clutch 15 to transmit the driving force of the motor 14 to the manual feed roller 3, and at the same time, the CPU 12 Start the internal timer.

When the driving force is supplied from the motor 14, the manual feed roller 3 starts rotating. At this time, the manual feed roller 3
Since the conveyance path length from the sheet feeding sensor 2 to the sheet feeding sensor 2 is 60 mm, the sheet feeding sensor 2 detects the sheet 1 second after the CPU 12 turns on the sheet feeding clutch 15. Since the detection signal of the paper feed sensor 2 is input to the CPU 12,
The CPU 12 can count this 1 sec by an internal timer started at the same time when the paper feed clutch 15 is turned on, and determines that the sheet is fed from the manual feed tray 6. In FIG. 3, a is a correction value in consideration of the distance from the registration roller 1 to the paper feed sensor 2.

In the present embodiment, since the conveyance path from the manual feed tray 6 is short and straight, the sheet 11
Is less likely to occur. Therefore, the CPU 12 does not operate for 0.1se after the sheet leading edge hits the registration roller 1.
The sheet feeding clutch 15 is continuously turned on during the period c to form a small loop in the sheet 11 and correct the skew of the sheet 11. After that, the CPU 12 operates the registration roller 1 to convey the sheet 11 to the image forming unit side (not shown).

As described above, the sheet feeding apparatus A of this embodiment
Is detected by the sheet feeding sensor 2 arranged on the common conveyance path 19 of the sheets 10 and 11 fed from the cassette 5 or the manual feed tray 6, and based on the detection signal of the sheet feeding sensor 2. The CPU 12 controls the operation of the registration roller 1 and the sheet feeding means (the cassette roller 4, the manual feed roller 3) to form a desired loop on the sheet to prevent the sheet from skewing. Even if a large number of manual feed trays 6 are provided, they can be arbitrarily selected by the mechanical switching means 14, and only one sheet feed sensor 2 for detecting a sheet is required, and the circuit configuration of the CPU 12 and the configuration of the sheet feeding device are simple. become. As a result, the present embodiment can provide an inexpensive sheet feeding apparatus having a simple structure and a small size. (Embodiment 2) Although the manual feed tray 6 and the cassette 5 are combined in the above embodiment, three or more sheet stacking means may be combined if the sheet stacking means having different transport path lengths are combined.

(Image Forming Apparatus) FIG. 4 is a view showing the schematic arrangement of an image forming apparatus 50 equipped with the sheet feeding apparatus A of each of the above embodiments.

As shown in FIG. 4, the image forming apparatus 50
Inside, a plurality of cassettes C1 and C2 (corresponding to the cassette 5 in each of the above-described embodiments) in which sheets are stored according to size are detachably mounted, an optical system 52 for reading a document, and a reading unit. A transfer unit (image forming unit) 54 that transfers the toner image formed on the photosensitive drum 53 to the sheet based on the image of the document that is formed, and a fixing unit 55 that fixes the toner image transferred on the sheet are arranged. Has been done.

Further, an intermediate tray 56 and optional cassettes C3 and C4 (corresponding to the cassette 5 in each of the above embodiments) are arranged in the lower part of the apparatus. And, on the side surface of the device above these cassettes C1, C2, C3, C4,
A manual feed tray 6 is attached.

Further, each cassette C is used as a sheet conveying path.
A conveying path 18 that guides the sheet from 1, C2, C3, and C4 to the photosensitive drum 53 side is formed, and a conveying path 17 that guides the sheet from the manual feed tray 6 to the photosensitive drum 53 is formed. Conveyor path 19 where
Are formed.

A registration roller 1 is arranged downstream of the conveyance path 19 in the sheet conveying direction, and a paper feed sensor 2 is arranged upstream of the registration roller 1 in the sheet conveying direction. A transport path 59 is formed between the transfer section 54 and the fixing section 55.

The sheet that has passed through the fixing section 55 is discharged to the outside of the image forming apparatus 50, or passes through the transport path 60 and is fed to the intermediate tray 56.

Since the image forming apparatus 50 as described above is equipped with the sheet feeding apparatus A having a simple structure and a low price as described above, the apparatus 50 itself has a simple structure and the product price is low. Become.

The sheet feeding device A in the above embodiment
Is configured so that the CPU 12 controls the operation time of the rollers 3, 4 and the registration roller 1 according to the time from the start of the operation of the cassette roller 4 or the manual feed roller 3 to the detection of the sheet by the paper feed sensor 2. However, the present invention is not limited to this, but based on the switching signal of the mechanical switching means 14 and the sheet detection signal of the paper feed sensor 2, that is, CP.
The operation control of the roller and the registration roller 1 may be performed without using the timer in U12.

[0039]

As described above, in the sheet feeding apparatus of the present invention, one of the plurality of sheet stacking means is selected by the mechanical switching means, and the selected sheet stacking means is selected. Sheets fed from the sheet are detected by a sheet detecting means installed in a common conveyance path of a plurality of sheet stacking means, and based on a detection signal of the sheet detecting means, the control means controls the sheet feeding means and the loop of each sheet stacking means. Since the operation of the forming means is controlled and a desired loop is formed in the sheet to prevent the skew of the sheet, even if a large number of sheet stacking means are provided, the detecting means for detecting the sheet is 1
The number of individual units is sufficient, and the circuit configuration of the control means is simple, and the structure of the entire device is simple and compact, and the product price is low.

Further, the image forming apparatus provided with such a sheet feeding apparatus has a simple structure as a whole and the product price is low.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a sheet feeding device showing an embodiment of the present invention.

FIG. 2 is a control block diagram of the sheet feeding device.

FIG. 3 is a flowchart showing a control state of the sheet feeding device.

FIG. 4 is an image forming apparatus including the sheet feeding device.

FIG. 5 is a schematic configuration diagram of a sheet feeding device used in a conventional image forming apparatus.

[Explanation of symbols]

 1 Loop Forming Means (Registration Roller) 2 Sheet Detecting Means (Feeding Sensor) 3 Paper Feeding Means (Manual Feeding Roller) 4 Paper Feeding Means (Cassette Roller) 5 Sheet Loading Means (Cassette) 6 Sheet Loading Means (Manual Feeding Roller) 10, 11 sheet 12 control means (CPU) 14 drive source (motor) 16 mechanical switching means 19 transport path 54 image forming means A sheet feeding device

Claims (3)

[Claims] 1. A plurality of sheet stacking means for stacking sheets, a feeding means arranged in each of the plurality of sheet stacking means, for feeding a sheet from the sheet stacking means to a sheet conveying path side, and a plurality of feeding means. A mechanical switching means for selectively connecting any one of them to a drive source, a loop forming means for forming a desired loop on a sheet sent from the feeding means selected by the mechanical switching means, and the loop. A sheet detecting unit arranged on a common conveying path connecting the forming unit and the plurality of sheet stacking units and detecting a sheet in the conveying path; and the loop forming unit based on a detection signal from the sheet detecting unit. A sheet feeding device comprising: a control unit that controls the operation of the feeding unit. 2. The control means controls the operating time of the feeding means and the loop forming means according to the time from the start of the operation of the feeding means to the detection of the sheet by the sheet detecting means. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is a sheet feeding apparatus. 3. The one of claims 1 and 2
An image forming apparatus, comprising: the sheet feeding device according to the item 1; and an image forming unit that forms a desired image on a sheet supplied from the sheet feeding device.