JP2700820B2 - Recording paper transport device for image recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like recording sheet conveying device used for an image recording apparatus such as an electrophotographic copying machine or a laser printer, and more particularly, to a two-sided recording on a sheet-like recording sheet. The present invention relates to an improvement in a recording sheet transport device in an image recording apparatus capable of performing the above operation.

[Conventional technology]

2. Description of the Related Art In general, in an image recording apparatus such as an electrophotographic copying machine or a laser printer, various techniques of an automatic double-sided recording apparatus capable of performing not only single-sided recording but also double-sided recording of recording paper have been proposed. In a conventional automatic two-sided recording apparatus, after an image is recorded on one side of a sheet in an image processing section, the sheet is temporarily stocked in the middle, the sheet is conveyed again, and sent to the image forming section. Such an automatic paper circulation / conveyance apparatus is disclosed in JP-A-59-82247 and JP-A-59-11422.
No. 7, JP-A-60-2241.

On the other hand, in addition to a double-sided copy mode in which images are recorded on both sides of the recording sheet, an image recording apparatus having image forming means in both modes of a multiple copy mode in which images of a plurality of originals are superimposed on one side of the recording sheet to obtain a copy image The technology relating to this has been developed and is disclosed in, for example, JP-A-62-123474.

According to the above publication, in the case of a single sheet multi-copy mode, a recording sheet fed, transferred, separated, and fixed is sent to a circulating conveyance path for the multi-mode, and then transmitted from the operation unit. It is supplied to the image forming unit again by the multiple copy command,
A copy image is formed on the same side of a recording sheet.

In the case of the single-sided double-sided copy mode, the recording paper is copied one side, and then is ejected once from the discharge roller to the outside to be reversed and turned upside down. The sheet is supplied to form a copy image on the opposite side of the recording sheet.

In the case of multiple copies of a plurality of sheets, the fixed recording paper is partially discharged by discharge rollers under the same control as that for the two-sided copy of the single copy, and then the discharge rollers are driven to rotate in reverse. It branches off from a part of the circulating transport path and is stored directly from the left end of the intermediate stacker. This operation is repeated, and the recording paper copied on the first side is all stored in the intermediate stacker. Thereafter, the recording sheet is sent out from the intermediate stacker by the next copy command, passes through the circulating conveyance path, reaches the image forming unit again, and the second surface is copied.

On the other hand, in the case of a plurality of double-sided copies, the control is performed in the same manner as in the single-sheet multiple copy, from the fixing device to a part of the circulating conveyance path, where it is branched and accommodated in the intermediate stacker. Subsequent operations are the same as in the above-described multiple copy.

FIG. 6 shows an example of the process of transporting the recording paper of a copying machine which enables such double-sided copying and multiple copying.

In the figure, reference numeral 3 denotes an image forming unit around the photosensitive drum 31;
Reference numeral 4 denotes a copy paper supply unit (paper feed unit), 5 denotes a copy paper transport unit, 6 denotes a fixing unit, 7 denotes a reverse discharge switching unit, 8 denotes a branch transport unit, and 9 denotes a stacker unit.

Next, the process of feeding copy paper will be described. In the figure, the dashed line indicates the copy paper transport path.

Recording paper (copying paper) P _A for storage by the single-sided copying paper feeding cassette or sheet feeding tray of the paper feeding unit 4 is fed one by one by the operation of the first sheet feeding means selected feed fed into the feed section 5A, in continuing the image forming section 3, the original image of the document placed is formed on the copy sheet P _a automatically or manually on the platen glass of the copier. Copy sheet P _A, which is copied on one side is heated and fixed by the fixing unit 6 through a conveyance belt of the conveyance section 5B.

A paper discharge path a for discharging to the outside of the apparatus by straight copy sheet P _A after fixing the downstream side of the fixing device 6, and the introduction path b for introducing the guide plate beneath the path for duplex copying, reverse discharge A reverse discharge switching unit 7 having a function of switching between the paper path c is provided.

Copy sheet P _B sent downward through the reversal sheet ejection switching unit 7 is fed is conveyed by reverse rotation roller of the branch conveying unit 8 to the stacker section 9.

The duplex copy mode, the copy paper P _B that is fed to the stacker section 9 straight switching gate means 91 of the inlet portion is discharged toward the lower left and U-turn by the reverse conveyance unit 92, the stacker substrate 93 Slides down the upper surface of the substrate, and after falling, slides down along the inclined surface of the substrate, reaches the tip stopper and stops.

Subsequent copy paper continuously sent to the stacker section 9
P _B is also one after another to slide the preceding copy sheet on P _B on the stacker substrate 93, and reaches the tip stopper becomes deposited state stops, the tip of the copy paper P _B are aligned.

Next, near the lower end of the inclination of the stacker substrate 93, a refeeding means is provided on the downstream side of the copy paper conveyance. The refeeding means is
It comprises a first paper feeding means 94, a separation paper feeding means 95, a second paper feeding means 96 and the like.

When refeed signal is input, the copy paper P _B that is stacked on the stacker substrate 93, the tip stopper 94C is lowered while being pressed from above by the pressing member 94A of the first sheet feeding means 94, under the fed out by the rotation of the feed roller 94B, only the copy paper P _B 1 of one bottom layer is delivered to the second sheet feeding means 96 are separated by the separation feeding means 95.

Roller one copy sheet P _B 1 which is fed is sandwiched in the second sheet feeding means 96 is further fed to the nip pressurized by feeding portion 5A between the discharge roller 97. The copy sheet P _B 1 is the back side copying of the copying paper P _B is performed subsequently in the image forming section 3, after being subjected to fixing in the fixing unit 6, the machine through the discharge path a of reversal sheet ejection switching section 7 It is discharged outside.

After then forming the first copy image of the document on one side of the copy sheet P _A, when set to multiple copy mode for forming a copy image of the second original on the same paper, the copy paper P _A to the aforementioned Similarly, the sheet is fed from the reversing sheet discharge switching section 7 to the entrance of the stacker section 9 via the branch conveyance section 8. In this multiple copy mode, have been gate plate rocking switching gate means 91 of the inlet section, fed by a copy sheet P _B is the side obliquely downward as indicated by broken lines, from the upper left side of the stacker substrate 93 Glide down to reach the tip stopper and stop. Then the copy paper
P _B is refeed means by refeed by discharge rollers 97, in the image forming section 3 through a feeding unit 5A, superimposed on the same one side of the copy paper P _B where the image of the first original is formed A copy image of the second document is formed, and is discharged outside the apparatus through the fixing device 6 and the paper discharge path a.

[Problems to be solved by the invention]

The recording paper transport device has a problem that the device becomes large and the structure becomes complicated.

In the copying machine disclosed in Japanese Patent Application Laid-Open No. 60-8863, the buffer tray (intermediate stacker) is inserted into the buffer tray with the leading edge first when the single-sided copy sheet is viewed away from the photoreceptor. At the time of re-feeding, the sheet is arranged so that the trailing edge is re-fed to the photoconductor, and a return path is provided between the buffer tray and the photoconductor. It is designed to be inverted once between them.

However, in this copying machine, the sheet conveyance path at the time of duplex copying has a complicated S-shaped curve and inversion.

Further, according to the re-feeding device of the image forming apparatus described in JP-A-58-43465, transfer paper feeding means for re-feeding is installed at both ends of the intermediate tray, and in the case of multiple copying, The transfer paper sent to the intermediate tray is sent out in the same direction as the paper advance.For double-sided copying, the transfer paper is reversed and sent out in the opposite direction to the paper advance to the photosensitive drum. The paper is to be re-fed.

However, this re-feeding device is not suitable for double-sided copying, in which a plurality of transfer sheets are copied on one side and deposited on an intermediate tray, and then the backside copy is collectively processed. Processing time is required.

[Means for solving the problem]

The present invention eliminates the above-mentioned problems in the recording paper transporting apparatus, and reduces the recording paper transporting during double-sided printing.
To provide a recording paper transporting device that smoothly and smoothly introduces an intermediate stack, accurately and stably introduces recording papers, aligns the papers in a predetermined storage unit neatly, and further reliably operates copy paper transporting in a duplex copying mode. It is the purpose.

The recording sheet transport device of the image recording apparatus according to the present invention that achieves these objects includes a recording sheet fed from a sheet feeding unit.
After recording the image on one side of the recording paper by the image forming unit,
An image recording apparatus that conveys and accumulates the recording sheet on an intermediate tray of a recording sheet conveying unit, and further re-feeds the recording sheet on the intermediate tray to the image forming unit to record an image on both sides of the recording sheet. A paper feed unit having a paper feed cassette is provided in a multi-stage configuration immediately below the image forming unit, an intermediate tray is arranged below the lowermost paper feed unit, and a conveyance path for introducing recording paper into the intermediate tray. Is provided below the bottom of the intermediate tray, and the recording paper conveyed in the lower conveyance path is turned upside down and sent to the intermediate tray via the introduction means. The paper feed means also serves as a paper feed means for re-feeding the paper, and the paper feed roller of this paper feed means is rotated forward when recording paper is introduced, and is switched to reverse rotation when re-feeding paper.

Further, in the recording paper transport device of the image recording apparatus of the present invention, the intermediate tray and the transport path are unitized,
It is characterized by being able to be pulled out to the outside.

Further, in the recording sheet transport device of the image recording apparatus of the present invention, the introduction unit also serves as a sheet supply unit for re-feeding the recording sheet, and rotates forward when the recording sheet is introduced, and reversely rotates when re-feeding the recording sheet. It is characterized by switching to.

〔Example〕

Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings. In the figure, portions having the same functions as those described above include:
The same reference numerals are given.

FIG. 1 is a configuration diagram of a two-sided copying apparatus equipped with a recording sheet transport device to which the present invention is applied, and FIG. 2 is a cross-sectional view of a main part of the recording device showing a paper feed circulation path by the recording sheet transport device at the time of duplex copying. It is.

In FIG. 1, 1 is an automatic document feeder, 2 is a scanning exposure optical system, 3 is an image forming section around a photosensitive drum, 4 is a copy paper supply section (feed section), 5 is a copy paper transport section, 6 Denotes a fixing unit, 7 denotes a reversal sheet discharge switching unit, 8 denotes a branch conveyance unit, and 100 denotes an intermediate tray sheet feeding unit according to the present invention.

As shown in the figure, the upper paper feed unit 4A and the lower paper feed unit 4B are fed from a recording paper bundle P housed in paper cassettes 41A and 41B detachably provided below the image forming unit 3. The recording paper (transfer paper) is sent out, and the photosensitive drum passes through the intermediate roller.
Conveyed to 31 circumference. Paper cassettes 41A and 41B that respectively store two types of recording paper P having different sizes are attached to the upper paper feed unit 4A and the lower paper feed unit 4B.

First, the structure of the sheet cassettes 41A and 41B will be described. In this case, the paper cassette 41A and the paper cassette 41B are
Since the structures are exactly the same except that the size or the partition plate is different from each other according to the size of the paper to be stored, the upper paper feed cassette 41A will be mainly described.

In FIG. 2, 42A is a cassette body, 43A is a movable bottom plate, and paper P is placed on the upper surface side. One end of the movable bottom plate 43A is rotatably locked to a part of the bottom surface of the cassette body 42A, and the other end is the peripheral surface of the pickup roller 44A via the sheet when the movable bottom plate 43A swings up. Press

 Next, the structure of each of the upper and lower paper feed units will be described.

The upper paper supply unit 4A includes a paper supply table 45A for storing and fixing the paper supply cassette 41A at a predetermined position, a push-up member 46A that pushes up the movable bottom plate 43A by driving a swing shaft, a pickup roller 44A, and a feed roller. 47A, reverse roller
And a paper feed mechanism section made of 48A or the like.

The lower paper feed unit 4B has the same structure as the upper paper feed unit 4A.

The image of the document D on the document table 21 is guided to the lens 25 via the first mirror 22, the second mirror 23, and the third mirror 24, and further guided to the photosensitive drum 31 via the fourth mirror 26. To form an electrostatic latent image, and the developed toner image
A, 41B to intermediate roller 51, tip detector 52, registration roller 5
The recording paper P, which is transferred by the transfer device 54 onto the recording paper P fed after passing through 3 and has the transferred toner image,
As a result, the photosensitive drum 31 is separated from the photosensitive drum 31 and sent to the fixing device 6 via the conveyor belt 56 to be fixed. If the recording paper P after fixing is a simple one-sided copy without performing double-sided copying or multiple copying, the switching unit 7 discharges the recording paper P onto the discharge tray 57 to complete the copying cycle.

The switching unit 7 changes the feeding path of the recording paper P according to the necessity of the transfer of the second original image by operating a selection button for performing one-sided copying or two-sided or multiple copying. It is sorted on the side of the unit 100 or on the side of the paper discharge tray 57.

When performing double-sided copying or multiple copying, the recording paper P on which the first document image has been transferred and fixed as described above is guided to the branch transport unit 8 by the switching unit 7 and temporarily stored on the intermediate tray 110. .

The intermediate tray paper feed unit 100 is installed below the lower paper feed unit 4B. The intermediate tray feeding unit 100 includes an intermediate tray 110, a sheet feeding / discharging unit 120 for loading and unloading the recording paper P into and from the intermediate tray 110, and a transport unit 130 disposed below the intermediate tray 110. Have been.

The intermediate tray 110 includes a tray body 111 and a movable bottom plate 112.
, A rear end stopper 113, and a front end paper aligning roller 114, and have substantially the same shape as the paper feed cassettes 41A and 41B. The rear end stopper 113 is moved and positioned according to the size of the recording paper P stored in the tray main body 111.

The leading edge paper aligning roller 114 can swing up and down and can be driven and rotated. When the recording paper P is inserted into the tray main body 111 from the paper supply / discharge unit 120 and stopped,
The leading edge paper aligning roller 114 descends and comes into pressure contact with the recording paper P, and by the drive rotation of the roller 114, the recording paper P is sent rightward in the drawing, and its leading end abuts against the inner wall end of the tray main body 111. The paper is aligned. The leading edge paper alignment is performed and aligned each time the recording paper P is inserted.

The paper supply / discharge unit 120 has a similar configuration to the paper supply mechanism in the paper supply units 4A and 4B. That is, a pickup roller 121 that can rotate in one direction, a feed roller 122 that is driven to rotate forward and backward at a fixed position, a reverse roller 123 that presses against the feed roller 122 and has a built-in one-way clutch or torque limiter, and an elastically deformable thin film And a flexible branch plate 124 made of

Below the bottom of the tray body 111, the movable bottom plate 112
And a swing shaft 126 for swinging the push-up member 125.

Below the tray main body 111, there are provided a plurality of sets of transport rollers 131, 132, 133 that can be driven and rotated, and a transport unit 130 including upper and lower guide plates 134. The transport rollers 131, 132, 1
The arrangement interval (pitch) of 33 is set shorter than the length of the recording paper of the minimum size. Note that the transport means 130 may have a configuration of a drive transport belt and a driven roller. Switching unit 7
The recording paper P sent to the conveying means 130 of the intermediate tray paper feeding section 100 from the second feeding section 8 through the branch conveying section 8 enters along the gap between the upper and lower guide plates 134 arranged opposite to each other, and
It is pinched by 1,132,133 and conveyed to the exit.

3 (A) and 3 (B) are explanatory views of a conveyance path of a recording sheet at the time of double-sided copying, and FIG.
The path to the stack is indicated by an arrow. (B) shows a transport path for re-feeding the recording paper P on which the single-sided copying has been performed and copying the backside.

When the copying is started in the double-sided copying mode, the first recording sheet P1 that has been subjected to the single-sided copying passes through the above-described paper feeding and conveying process, passes through the conveying rollers 131, 132, and 133, and then pushes up the branch plate 124 to feed and discharge the paper. The recording papers P2 and P3 that are stored in the intermediate tray 110 from the means 120 and are successively successively stacked on the upper surface of the preceding recording paper of the intermediate tray 110. At this time, the feed roller 122 is driven and rotated in the reverse direction (clockwise), and the reverse roller 123 is unlocked and becomes free, and is pressed against the feed roller 122 and is driven to rotate counterclockwise. Thus, by the rotation of the rollers 122 and 123, the recording sheets P1, P2 and P3 sent are nipped and sequentially stored in the intermediate tray 110.

When copying is resumed after all the one-sided copying is completed and the back side of the original is set, the push-up member 125 in the tray body 111 is rocked and pushed up, and the loaded recording paper bundle is picked up by the pickup roller 121. Press on the peripheral surface.

Next, the feed roller 122 and the pickup roller 121 are converted to forward rotation drive, and the reverse roller 123 is prevented from rotating forward (clockwise rotation) to prevent double feed. By this paper feeding operation, one of the uppermost recording sheets P3 of the bundle of recording sheets stored in the tray main body 111 is first sent out, and after the image formation via the intermediate rollers 58 and 51, the conveyance direction is changed. Output tray via set reverse output switching unit 7
It is discharged and placed on 57. Subsequently, the lower-order recording sheets P2 and P1 in the tray main body 111 are sequentially sent out, pass through the above-described transport path, and are stacked on the sheet discharge tray 57.

The above is a case of two-sided copying of a two-sided document on a plurality of recording sheets. By placing the recording sheet in the intermediate tray 110 with the image surface facing upward and feeding it upward, the image is printed on the back of the recording sheet. There is an advantage that image show-through due to show-through or rubbing is less likely to occur.

FIG. 4 is a sectional view showing another embodiment of the recording sheet conveying device according to the present invention. In the drawings, parts having the same functions are denoted by the same reference numerals as those in the embodiment. Further, points different from the above embodiment will be described.

This is near the paper exit of the intermediate tray paper feed unit 100.
It is characterized in that a carrying-in means is provided in an upper part and a carrying-out means is provided in a lower part, and recording paper P is introduced from above and sent out from the bottom.

The carry-in means comprises a drive roller 141 and a driven roller 142 and rotates in the direction of the arrow to sequentially introduce the recording paper P into the tray body 111 from above.

The unloading means includes a half-moon-shaped pickup roller 143, a feed roller 144, a reverse roller 145, a stopper member 146, and a pressing member 147. The stopper member 146 swings and retreats downward when the recording paper P is sent out. The pressing member 147 swings upward and retracts when the recording paper P is introduced.

When the recording paper P is introduced into the tray body 111,
The pressing member 147 swings and retracts upward, and the conveying rollers 131, 132, and 133 are rotated by the pressure rotation of the driving roller 141 and the driven roller 142.
The recording paper P fed from the nip is nipped by the rollers 141 and 142 and is accommodated and deposited in the tray main body 111 from above.

When re-feeding the recording sheet P to the image forming section, the pressing member 147 descends to press the recording sheet bundle from above, and the stopper member 146 descends to retreat below the tray main body 111 bottom. Next, the pickup roller 143, the feed roller
144 is driven and rotated to feed out one recording sheet P in the lowermost layer of the recording sheet bundle.

FIG. 5 is a cross-sectional view of the intermediate tray paper feed unit showing the transport path of the recording paper P in the multiple copy mode. When the multiple copy mode is set, the recording paper P is transported by the transport rollers 131, 132,
The sheet is directly carried into the tray main body 111 from above the left end thereof without passing through the route 133.

A guide member 115 that can move according to the size of the recording paper P is provided at the upper left of the tray main body 111, and the leading end of the guide member 115 is surely located near the right end of the inner wall of the tray main body 111 without falling down on the way. Trying to reach.
Further, similarly to the duplex printing mode, the leading edge paper aligning roller is provided.
By the vertical swing and drive rotation of the 114, the leading end of the recording paper comes into contact with the abutting portion of the tray main body 111, and the paper is aligned and stacked. After the stacking, the sheet is fed again by the right end sheet feeding means in the same manner as described above.

The intermediate tray paper feed unit 100 is formed as a unit, and slide rails 102 and 103 are provided on both side surfaces of the unit housing 101 so that the intermediate tray paper feed unit 100 can be pulled out from the recording apparatus main body. When the recording paper P is jammed in the paper feeding / discharging means 120 or the conveying means 130, if the unitized intermediate tray paper feeding section 100 is pulled out forward along the slide rails 102 and 103, the inspection and inspection can be easily performed. Correction can resume paper feeding.

Further, the intermediate tray paper feed unit 100 is used for stacking recording paper at the time of double-sided copying or multiple copying. However, the intermediate tray 110 can be used as an auxiliary paper feeding cassette. That is, recording paper of a size other than the paper feed cassettes 4A and 4B, extra-large recording paper, or recording paper of a special size is stored in the tray main body 111 of the intermediate tray 110, and the paper It is also possible to feed paper by means 120. Replenishment and replacement of these recording sheets can be easily performed by pulling out the intermediate tray sheet feeding unit 100 forward.

Further, the tray main body 111 is arranged inclined, and
The recording paper 20 may be arranged obliquely to ensure the leading edge of the recording paper accommodated in the tray body.

Further, in this embodiment, the paper feed cassettes 4A and 4B and the intermediate tray 110 are arranged in tandem, but the paper feed cassette is disposed on the right side of the recording apparatus main body, and the intermediate tray paper feed unit 100 is located immediately below the image forming unit, , May be arranged at a position corresponding to the stacker 9 in FIG.

〔The invention's effect〕

As described above, according to the present invention, the intermediate tray and the paper supply / discharge unit are provided below the image forming unit, and the recording paper conveyance unit is further provided below the image forming unit. Since the forward / reverse rotation device required to switch back the paper is not required, the operation is stable, smooth, and the structure is simple. Further, since the means for introducing the recording sheet into the intermediate tray and the sheet re-feeding means can also be used to feed and discharge the paper by forward and reverse rotation by the same means, the paper feeding and discharging mechanism can be simplified and reduced in size.

Further, not only can the overall height of the intermediate tray paper feeding unit be reduced and the thickness can be reduced, but also the radius of curvature of the recording paper in this paper feeding unit can be increased with a margin within this overall height. An excellent effect is obtained without giving excessive stress and without causing a conveyance failure.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a two-sided copy recording apparatus equipped with a recording paper transport apparatus to which the present invention is applied, FIG. 2 is a cross-sectional view of a main part of the recording apparatus showing a paper feed circulation path by the transport apparatus, and FIG. FIG. 4 is an explanatory diagram of a recording paper transport path during double-sided copying, FIG. 4 is a cross-sectional view showing another embodiment of the recording paper transport device according to the present invention,
FIG. 5 is a cross-sectional view of an intermediate tray paper feeding section showing a recording paper transport path in a multiple copy mode, and FIG. 6 is a configuration diagram of a conventional duplex copying apparatus. 3 image forming unit, 4, 4A, 4B paper feed unit 5 transport unit 7, reverse discharge switching unit 8 branch transport unit, 41A, 41B paper cassette 100 intermediate Tray feeding section 101 Unit housings 102, 103 Slide rail 110 Intermediate tray 111 Tray body 112 Movable bottom plate 113 Rear end stopper 114 Roller for leading edge paper alignment 115 Guide Members 120, feeding / discharging means 121, 143 Pickup rollers 122, 144 Feed rollers 123 Reverse rollers 124 Branch plate 125 Push-up members 130 Transport means 131, 132, 133 Transport rollers 134 Guide plate, 141: drive roller 142: driven roller, 146: stopper member 147: pressing member P, P1, P2, P3: recording paper

Claims (2)

(57) [Claims] An image forming section records an image of a recording sheet fed from a sheet feeding section on one side of the recording sheet, and then conveys and accumulates the recording sheet on an intermediate tray of a recording sheet conveying section. An image recording apparatus for re-feeding the recording sheet in the intermediate tray to the image forming section and recording an image on both sides of the recording sheet, comprising a multi-stage sheet feeding section provided with a sheet feeding cassette immediately below the image forming section. In addition, an intermediate tray is arranged below the lowermost sheet feeding unit, and a transport path for introducing recording paper to the intermediate tray is provided below the bottom of the intermediate tray. The recording paper is turned upside down and sent to the intermediate tray via the introduction means. The introduction means to the intermediate tray also serves as a paper supply means for re-feeding the recording paper. Roller is forward when loading recording paper A recording paper transport device for an image recording device, wherein the recording paper transport device switches to reverse rotation when the paper is fed and re-fed. 2. The recording sheet conveying device according to claim 1, wherein the intermediate tray and the conveying passage are unitized and can be pulled out to the outside.