JPH03267249A - Special paper feeder in image forming device - Google Patents

Abstract

PURPOSE:To make the conveyance of a sheet of special paper so as to be favorably performable by setting a special paper conveyor to the side of a paper conveying passage, while performing a conveying operation in a state of holding a side portion of the special paper in between, and setting up it automatically only at the time of conveying the special paper. CONSTITUTION:Such a special paper conveyor 50 as movable up and down is installed in the side of a paper moving route PL of a paper conveying passage. In front and in the rear of this conveyor 50, there are provided driving rollers 55, 56 and pinch rollers 57, 58 respectively. At the up position, a side part of paper being conveyed along the conveying route PL is held in between by those of pinch roller 57, driving roller 56 and pinch roller 58, driving roller 56, and the paper is conveyed by each driving force of these driving rollers 55, 56 which are interlocked with each other. Accordingly, when the special paper is detected, the conveyor 50 is operated to go up, and at time of conveyance of ordinary paper, it is lowered whereby the top face of a guide plate 53 at the upper part of the feeder 50 is accorded with the route PL. Therefore both special and ordinary sheets of paper are conveyable so well.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a paper conveyance device installed in a paper conveyance path of a copying machine, and particularly for copying on special paper such as small-sized and thick paper such as postcards. The present invention relates to a control means for automatically setting the special paper conveying device when carrying out the setting.

(Prior Art) When copying on paper that is normally used in Hi& such as a copying machine, the paper is stored in a paper feed cassette, etc., and the paper is loaded into the paper feed device of the copying machine. Depending on the copying mode, the toner image is sent to an image transfer part such as a photoreceptor drum, the toner image formed on the photoreceptor drum is transferred, and then it is transported to a fixing device to perform fixing and create a copy. .

In the above-mentioned general copying machine, among the standard size paper normally used, paper up to about B5 size can be transported in good condition by the paper transport Vl position provided in the main body of the copying machine. be exposed.

However, when transversely feeding envelopes or copying small-sized, thick paper such as postcards, there are some problems such as the fact that normal belts, rollers, and other conveying means cannot convey the paper well. A problem occurs.

Such a problem of poor conveyance inside a copying machine is particularly difficult to occur in a paper conveyance device provided between a photosensitive drum and a fixing device. However, in this portion, it is necessary to carry out the conveyance in such a way that the conveyance means does not come into contact with the surface of the paper carrying the unfixed toner image.

For this purpose, it is required that the sheet be transported between the photosensitive drum and the fixing device in such a manner that the surface of the sheet carrying the unfixed toner image is not in contact with the surface of the sheet.

Therefore, in devices such as copying machines that are operated by boat, a suction belt device is often used as a paper conveyance device. A paper conveying device using this suction belt has a vacuum chiton bar provided on the underside of the belt, and sucks air through the vacuum bar to perform an operation of pressing the back side of the paper against the belt.

Then, the paper is moved according to the movement of the belt, and the paper on which the toner image has been transferred is transferred to the image transfer section of the photoreceptor drum.
The belt is in contact with the back surface of the sheet and the sheet is conveyed toward the fixing device.

The paper conveyance device having the above configuration is a type II used in many copying machines, and is a device that can exhibit relatively good conveyance performance for normal size copy paper. .

(Problems to be Solved by the Invention) When the paper conveyance device of a copying machine is configured with a suction belt device as described above, for example, it is necessary to In contrast, good conveyance performance can be achieved.

However, problems arise, such as the inability to provide good conveyance performance for small-sized paper such as postcards, or for small-sized, curled paper.

In addition, a suppression roller device or the like is arranged on a conveying means such as a belt provided between the image recording transfer section from the photosensitive drum and the fixing device, so that the edge of the paper is nipped between the roller and the belt. When a small-sized paper is conveyed in this state, the roller presses the toner image, causing a problem such as disturbances in the image at the edges.

Therefore, in order to solve the above-mentioned problems, for example, as shown in Japanese Patent Application Laid-Open No. 1-288871,
A special paper conveyance device is arranged separately from the conveyance device, and the special paper conveyance device is operated for paper of a special size, and can be covered so that small size paper such as postcards can be transported well. Proposed.

However, even when using the means shown in the conventional example, there are still problems with the structure of the special paper conveyance device, the drive means for postcards, etc., and the mechanism for moving the special paper conveyance device relative to the conveyance device. , many problems have arisen that require solutions.

Furthermore, when using a method in which the control panel of Image Formation II is provided with an operating means such as a set button, and the operator operates the button to set the special paper transport device to the operating position, the operator can set the special paper transport device to the operating position. If the operator forgets to manipulate the paper, the special paper conveying device will not operate for small-sized paper, resulting in paper jams and the like.

Also, with the special paper transport device set to -,
When feeding normal size paper, problems such as disturbing the toner image at the edges of the paper may occur.

(Object of the invention) The present invention is directed to the conventionally used 5A as described above.
The present invention solves the drawbacks of @, and includes four control means that automatically cause the special paper conveyance device to perform servicing with respect to the conveyance device only when a signal for conveying special paper is input. is intended to provide.

(Means and effects for solving the problems) The special paper feeding device of the image forming apparatus of the present invention includes a paper transporting device between the image transfer section from the photosensitive drum of the image forming device and the fixing device, The present invention relates to a device in which the paper conveyance device is provided with a conveyance means for special paper.

In the special paper feeding device of the image forming apparatus of the present invention,
The special paper transport device is moved to the operating position by a signal from an image information output device to the printer, and when transporting special paper such as a paper wrapper 4, the special paper transport device is set on the side of the paper transport path, and the The structure is such that the conveyance operation can be performed while the side portions of the special paper are being held.

Furthermore, in the apparatus of the present invention, a setting means corresponding to small-sized paper is disposed on the control panel, and the setting means is configured to avoid moving the special paper conveying device, and the paper size obtained from the paper tray is A means is provided for comparing the signal from the special paper transport device with the signal from the position detection means, and when the two signals do not match,
It is possible to configure the special paper conveying device to be positioned by the setting means of the control panel.

Further, the control device of the image forming apparatus of the present invention is set with means for positioning the special paper conveying device at the time when the copying cycle is completed, and the copying cycle is adjusted according to the mode set in the control device. The position of the 14 special paper transport device at the time of termination can be set, and when a paper jam signal is input to the W control device, the special paper transport device is operated to return to the inoperative position. I can do it.

In the present invention, when the signal for moving the special paper transport device to the operating position is input to the control device of the image forming apparatus, the special paper transport device til! It is possible to output a drive signal from the control device so as to start the copy cycle by first performing the operation of moving 7 and using a means such as a timer to delay the signal.

In addition to this, a paper size detection means is disposed on the paper conveyance path from the paper supply means to the image transfer position, and the paper size detection means is arranged based on the paper size signal from the detection means or the paper size signal from other means. It is also possible to configure the special paper transport device to operate on the upper back.

By providing the special paper conveyance device configured as described above, the image forming apparatus of the present invention can efficiently convey small-sized paper, and the conveyance between the image transfer section and the fixing device is It is possible to prevent paper jams from occurring due to reasons such as insufficient conveyance capacity of the device.

Further, when the special paper transport device is driven by a signal from the image information output device, it is possible to prevent setting errors of the special paper transport device from occurring, and the burden on the A verator can be reduced.

Furthermore, even if a means is provided to automatically move the special paper transport device based on the setting of the movement timing of the special paper transport 1i1 and a signal from the paper size detection means, it is possible to It is possible to perform a good conveying action for both small-sized paper and paper.

(Example) According to the illustrated example, the special paper feeding device of the present invention is
The configuration when used in combination with an image forming apparatus will be described.

An image forming apparatus to which the present invention can be applied is shown as a printer 1 in FIG.
, and a lower cabinet 3 provided with a plurality of paper trays and an intermediate tray.

In the printer 1 shown in FIG. 1, a special paper transport device 50 is provided for the paper transport device 23 disposed between the photosensitive drum 10 and the fixing device 16.

The printer 1 shown in FIG. 1 shows the configuration of an internal printer, and a writing device 11 using a laser beam is arranged on the photoreceptor drum 10 of the printer 1. The image information inputted to 11111 is written on the photosensitive drum 10.

Note that the device for outputting image information to the writing device may be an image reading device or any other device.

Around the photoreceptor drum 10, there is a charging corotron 12 and an electrostatic charger for uniformly charging the photoreceptor drum. I3
A developing device 13 for attaching toner to the image, a transfer/separation corotron 14 for transferring the toner image formed on the photosensitive drum onto paper, a cleaning device 15, and the like are arranged.

Further, the paper is stored in the paper tray 5 and loaded into the paper feed unit 6 of the printer, and the paper is fed from the tray 5 to the paper 1 by the paper feed roller 7 of the paper feed device and the paper sorting device 8. will be carried out.

When copying the special paper stored in the paper tray 5 or the special paper inserted from the manual feed tray, input is made using a set button or the like on the control panel (not shown), or Based on the paper size information from the paper tray, it is possible to input information about copying on special paper.

Then, based on the information input to the control device of the apparatus by the input means, the transport means 50 for the special paper is
is moved toward the paper conveyance device so that it can carry out the operation for conveying special paper.

As described above, a toner image is transferred onto the paper sent out from the paper tray by discharge from the transfer corotron, and the paper is transferred to the paper transport device 23.
conveyed to the fixing device 16 by the fixing device, and in the fixing device,
By applying heat and pressure, it is fixed and comes out to the initial exit 28.

In addition, in the above embodiment, the cleaning web 17 is arranged with respect to the heating roller of the fixed @ device @ 16,
The cleaning web 17 acts to apply silicone oil and to connect the surface of the roller.

The paper conveyance path connected to the printer is the paper tray 5.
A registration gate 21 and a registration roller 22 are disposed at the end of the paper feed path 20 immediately before the image transfer section of the photoreceptor drum, and these means position the leading edge of the paper and transfer the image onto the photoreceptor drum. The paper is fed out in synchronization with the toner image.

The paper to which the toner image has been transferred from the photoreceptor drum is
It passes through the fixing device 16 and is conveyed through a discharge path 25, but in the middle of the discharge path 25, there is a soil tillage path 2 through a gate 27.
9 is provided, and the paper is transferred to the upper tray 30 or the first exit 28.
can be discharged to the discharge tray via the

Further, the non-discharge path 31 provided from the first exit path 25 via the gate 26 is provided with a curl removal device 32,
It is possible to eject the paper to another initial output tray, sorter, etc. through the gate 33 in a state where the paper is not curled, or to send the one-sided copy flow paper towards the return path 35 connected to the lower part of the paper. be made into

The kitchenette 3 disposed at the bottom of the main body 2 of the printer is provided with a plurality of paper trays, an intermediate tray 40, and a return path 35 and a paper transport path 38 that penetrate vertically on both sides thereof. ing.

Further, a branching gate 36 for the intermediate tray 40 and a reversing path 37 are disposed in the return path 35, and by feeding the single-sided copied paper to the intermediate tray via the reversing path 37, the sheet is reversed. The 14-sided copy performance sheet can be fed out for reverse side copying by storing the sheet in the intermediate tray in the same state.

In the cabinet 3, paper trays 5a and 5b, a large capacity tray 5C, and an intermediate tray 40 are arranged vertically. Paper units 6a, 6b and 6C are arranged.

The paper feeding unit is composed of means for transporting paper from each paper tray and means for connecting the paper transport paths of the upper and lower units. A conveyance path is configured. Note that in the case where a paper feeding unit from an intermediate tray is provided in the middle of the paper feeding unit, all paper transport paths of the paper feeding section are connected, so paper can be fed from any paper tray. I can do it.

Further, unlike a normal intermediate tray, the intermediate tray 40 does not store a large number of sheets with single-sided copies on top of one another; instead, the intermediate tray 40 stores single-sided copied sheets introduced from the return path 35 during the copying operation of the main body. We are using a device that is configured so that it can be sent out sequentially depending on the situation.

The intermediate tray 40 is composed of upper and lower guide plates, a plurality of sets of diagonal feed rollers 41, a gate 42 disposed at the end on the feed side, and a conveyor roller device.

Then, the single-sided copied sheets stored in the tray through the gate 36 are stopped while being aligned by the diagonal feed roller, and a signal for copying the back side is output from the image forming apparatus main body. In response to this, the gate 42 is opened so that the single-sided copy sheet can be sent out toward the image transfer section.

(Configuration of Special Paper Conveyance Device) The mechanism of the special paper conveyance device E50 of the present invention will be explained according to the embodiment shown in FIGS. 2 and 2a. Second
In the side view shown in the figure, the paper transport device r! of the present invention is shown.
I50 is for the main body frame of the image formation command,
A frame 51 is provided so as to be movable downward by one direction via guide posts 52, 52a, and a drive row 555 is attached to the frame 51.
．． 56 and pinch rollers 57 and 58 are installed.

In order to drive the roller device, a (
A gear A7 device G1 and a special paper conveyance S+i position driving device G2 are provided, and gears G2 to G3 of the special paper conveyance device mesh with the gear G2 to drive the drive rollers of the special paper conveyance device. Make sure to do the following.

A plurality of gears G3 to G7 are arranged in the special paper conveyance device, and these gears 03 to G7 drive the drive rollers 55 and 56, and between them and the pinch roller,
The function is to carry out the paper conveyance function.

In the special paper conveying device 2250, the device is arranged so that the nip position between the drive roller and the pinch roller corresponds to the paper moving surface PL (the upper surface of the belt of the conveying device), as shown in FIG. If it is available, the special paper transport device is set to the operating position.

On the other hand, as shown in FIG. 2a, when the special paper transport device is lowered, the upper surface of the guide plate 53 provided at the top of the device is positioned in accordance with the paper movement path PL. , which guides the paper conveyed by the conveyance device.

Further, at the lower level position of the special paper transport device, the roller drive gear G3 is separated from the gear A device G2 of the main body, so each roller device of the special paper transport 'aH is maintained in an inactive state. Ru.

Note that the special paper conveyance device means of the present invention can use any drive mechanism; for example, a solenoid drive means is connected to the gear device G1, and the drive force from the drive shaft 59 is applied. Accordingly, means such as moving the special paper conveying device up and down can be used.

(Means for setting the position of special paper conveyance device) In the embodiment of the special paper conveyance device shown in FIGS. 1 and 2, the following control means can be provided.

First, in the printer of the present invention, paper size information is output together with image information from the image information output gi to the printer, and paper selection is performed based on the paper size signal. can be used. When a small size paper is selected when the signal is output, a signal for driving the special paper transport device is simultaneously output, and preparations for transporting the small size paper are made.

In addition, separate from the above embodiment, a paper detection means is arranged in the middle of the paper conveyance path connecting each paper tray and the image transfer section, and a detection signal from the detection means is inputted to the control device. It is also possible to detect the paper size using information such as the time it takes for the paper to pass through the detection means, and to set a special paper conveyance device.

In addition to the above-mentioned means, as conventionally used in electronic copying machines, the paper feed cassette or paper tray is provided with a paper size display means, and a detection means placed in the paper feed device detects each paper size. Information on the size of paper stored in the paper storage device is input in advance to the υ control V device. Then, a means is provided to select the paper based on the paper size signal sent together with the image information, feed the paper from a predetermined paper storage device, and create a bee. You can also do it.

(2) A control panel is provided on the main body of the printer, and a setting means (for example, a button for displaying small size paper) corresponding to small size paper is arranged on the control panel. The special paper conveying device can be configured to be moved by an operator pushing the setting means.

Along with the set button, the four controllers of the printer include means for comparing the paper size signal obtained from the paper tray or the signal from the special paper transport device position detection means with the special paper transport device position signal. provided in 1.
．． In the II all system, if the two signals do not match, the special paper conveying device is configured to be positioned by the setting means of the control panel.

To specifically illustrate the control means of the embodiment, the control device is constructed as shown in FIG. That is, the control II device 60 receives a paper size signal from a paper size detection means 61 installed on the paper transport path of the printer and a paper size signal from the image information output device 62. Further, a position signal 63 of a special paper conveyance device provided corresponding to the conveyance device "t" is inputted to the control device 60 from another circuit.

Therefore, the control device compares one of the two signals of vi and the position signal of the special paper conveying device,
If the position of the special paper transport device does not match the printer operation signal for small size paper input to the printer, the signal ratio section 64 outputs a command to press the set button 65. .

Then, after the operator presses the set button 65 to move the special paper transport device and set the special paper transport device to the upper back position, copying work is performed on paper with small 4 noise. Configure it to do so.

The drive mechanism of the special paper transport device of the present invention lowers the special paper transport device to an inoperative position when the special paper transport device is in the top four positions and a copy end signal is input to the control device. It is possible to perform such control.

Also, if the paper tray becomes empty during copying work, and No. 43 detected by the no-paper sensor installed on the paper 1 to tray is directed to the control device, , 1III that would cause the special paper conveyance device to become inconvenient.
It is possible to do IIIl.

Furthermore, by setting the driving modes for the three types of special paper transport devices described above to t, lI, and Ill devices, the printer can be controlled arbitrarily.

The positioning means of the special paper transport device [50] is set in the 1.111tl device of the 0 image forming 5A device at the time when the copy cycle is completed, and the copy cycle is adjusted according to the mode set in the control device. At the end of (cycle down)
The configuration is such that the position of the special paper transport device can be set. Further, even when a paper jam signal is directly input to the control mg, the special paper conveying device can be automatically returned to the inoperative position.

For example, in the printer of the present invention, it is also possible to configure the special paper transport device so that the special paper transport device is always operated at the operating position (upper back position) of the special paper transport device. In that case, the special paper transport tiiiin can perform an auxiliary action for transporting normal-sized paper as well. This can be particularly effectively used in cases such as thick paper, film, etc., which cannot be transported satisfactorily depending on the belt transport means.

Therefore, in the present invention, during copy cycle down, the special paper transport device is stopped at the operating position, and when the next copy signal is input, the special paper transport device is activated/deactivated.
The first mode can be selected arbitrarily. Further, in the embodiment described above, it is also possible to add a means for stopping the special paper conveying device at the lowered position 1 during cycle down.

Further, in the control device of the present invention, a means is provided for lowering the special paper transport device when the signal is inputted to the control device when a dirt occurs in the paper transport path. I can do it.

゛If the control device is configured as described above, the special paper conveyance device may be lowered with the postcard etc. nipped in the roller device of the special paper conveyance device, but this is more convenient for jam removal work. It will also bring good results.

(2) In the apparatus of the present invention, when the signal for moving the special paper transport device to the operating position is input to the control device of the image forming apparatus, the operation for moving the special paper transport device is performed first. Make it.

Then, the actuation signal is processed using means for delaying the signal, such as a timer, and after a certain period of time, a drive signal is output from the control device to start the P cycle. You can do it like this.

For example, the standby position 1 of the special paper conveying device shown in FIG.
When the main body is moved to the operating position, the drive gear A of the main body engages with the gear of the special paper conveyance device, and the driving of the roller device provided in the B+ special paper conveyance device is started. However, if the conveyance roller device of the special paper conveyor is connected while the paper conveyance device of the image forming equipment is being driven, a large load will be placed on the drive system, causing changes in the conveyance speed etc. A problem occurs.

Therefore, in the present invention, for small size paper]
When a copy creation command is output, based on that signal, the special paper transport device is first moved to the upper position 1, and the gears of the drive system are kept in mesh. to start driving.

Furthermore, in order to drive the two means at predetermined timings, it is possible to provide means for delaying the drive time in the ill device via a timer or the like to maintain the timing of the operation of each member in a good state. Make it possible.

■In addition to the above-mentioned υ control means, the printer of the present invention uses paper size information from the paper storage 1ffi to control paper selection, as has been conventionally used in electronic copying machines. It can be configured to perform an action.

For example, as shown in Japanese Patent Publication No. 61-49208, paper size display means is provided in the paper feed cassette or paper tray, and a detection means is placed in the paper feed device, so that the Information on the size of the paper stored in each paper storage device is input in advance to the control device.

It is also possible to provide a means for selecting paper based on the paper size signal sent along with the image information, feeding the paper from a predetermined paper storage device, and making a copy. .

In addition to the paper I noise signal from the paper storage device 2 as described above, in the present invention, a sensor is placed at a predetermined position in the paper transport path, and the length of the paper is detected by the sensor. Based on that information, operations t and IIm of the special paper conveying device can be performed.

That is, in the paper conveyance path 20 shown in FIG.
It is possible to place sensor I81 in the middle of the paper feed path from paper tray 5, or to place sensor S2 in the paper feed path from manual feed tray 4.
It is possible to use means for detecting the length of the paper passing through each paper transport path by arranging the paper transport path.

The special paper transport device can be configured to move upward based on information about the length of the paper passing through the paper transport path.

Further, as described above, when performing a copying operation on special paper (small size paper), means is provided to prevent an image from being formed at the portion where the pinch roller of the special paper conveying device comes into contact. For example, as shown in FIGS. 1 and 4, an erase lamp 70 is installed between the exposure section and the development section of the photosensitive drum 10.

Then, the erase lamp 70 is caused to emit light at a portion corresponding to a predetermined area d at the edge of the small-sized paper to erase the written image, and the area at the edge of the paper where the roller is pressed is activated. First, a process is performed to prevent a toner image from being formed.

As described above, in the present invention, a process such as transferring an image to a small-sized paper is performed, and the special paper transport device is raised to perform a transporting action on the small-sized paper. I can do it.

In addition, it is possible to convey special paper such as postcards in a good condition, and the pinch roller of the special paper conveyance device is also prevented from being soiled by toner images.

In addition, in the above-mentioned embodiments of the present invention, the case of a printer was explained, but the apparatus of the present invention can also be applied directly to a digital type electronic copying machine or any image forming WA directly. However, the present invention is not particularly limited to those applied to printers.

(Effects of the Invention) Since the special paper feeding device of the image forming apparatus of the present invention has the configuration as described above, by providing the special paper feeding device configured as described above, it is possible to reduce the amount of paper that is Paper can be conveyed satisfactorily, and paper jams can be prevented from occurring due to reasons such as insufficient conveyance capacity of the conveyance device.

Further, when the special paper transport device is driven by a signal from the image information output device, it is possible to prevent setting errors in the special paper transport device from occurring, and the burden on the operator can be reduced.

Furthermore, when installing a means to automatically move the special paper transport device based on the timing settings for the movement of the special paper transport device and the signal from the paper size detection means, it is possible to It is possible to perform the conveying action favorably with both small-sized paper and small-sized paper.

[Brief explanation of drawings]

Fig. 1 is a side view of a printer equipped with the special paper feed device of the present invention, Fig. 2 is a side view of the special paper transport device in a soil condition, and Fig. 2a is a side view of the special paper transport device in the lowered position. 3 are block diagrams of the control means used in the present invention, and FIG. 4 is an explanatory diagram of the photosensitive drum and the erase lamp. Reference numeral 1 in the diagram: Printer 10: Photosensitive drum, 16: Fixing device, 22: Registration roller, 23: Conveyance Device, 50...
・Special paper transport device, 51...Frame, 55
・56・・・・Drive roller, 57・58・・・・
・Bin roller, 59... Main body drive shaft, 60.
... Control device, 70 ... Erase lamp.

Claims (5)

[Claims] (1) In an image forming apparatus, a paper conveyance device is provided between an image transfer section from a photoconductor drum and a fixing device, and a conveyance means for special paper is provided for the paper conveyance device, wherein the special paper conveyance is provided. The device is moved to the operating position by a signal from the image information output device to the printer, and when conveying special paper such as postcards, the special paper conveyance device is set on the side of the paper conveyance path, and the special paper conveyance device is set on the side of the paper conveyance path. 1. A special paper feeding device for an image forming apparatus, characterized in that it is configured to be able to carry out a conveying operation while its side portions are being held. (2) In the image forming apparatus, a setting means corresponding to small-sized paper is arranged on the control panel, and the special paper conveying device can be moved by the setting means, and the size of the paper obtained from the paper tray is A means is provided for comparing the signal from the special paper transport device with a signal from the position detection means of the special paper transport device, and when the two signals do not match, the special paper transport device is positioned by a setting means provided on a control panel or the like. A special paper feeding device for an image forming apparatus characterized by: (3) Set the positioning means for the special paper transport device at the time when the copy cycle ends in the control device of the image forming apparatus, and set the positioning means for the special paper transport device at the time when the copy cycle ends according to the mode set in the control device. Claims characterized in that the position of the special paper transport device can be set, and when a paper jam signal is input to the control device, the special paper transport device is returned to an inoperative position. 2. A special paper feeding device for an image forming apparatus according to item 1. (4) When a signal to move the special paper transport device to the operating position is input to the control device of the image forming apparatus, the operation to move the special paper transport device is performed first, and a signal such as a timer is activated. A special paper feeding device for an image forming apparatus according to claim 1, wherein a drive signal from a control device thereof is outputted so as to start a copy cycle using delaying means. . (5) A paper size detection means is disposed on the paper transport path from the paper supply means to the image transfer position, and based on the paper size signal from the detection means or the paper size signal from another means, The special paper feeding device of an image forming apparatus according to claim 1 or 2, characterized in that the special paper feeding device is configured to cause the special paper transporting device to perform a lifting operation.