JPH0651555B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer, and more specifically, to image formation on both sides of a sheet or on the same side of a sheet. The present invention relates to an image forming apparatus having a double-sided or multiple image forming mechanism.

(B) Conventional Technology In recent years, image forming apparatuses, such as copying machines, have become multifunctional, and apparatuses having a double-sided copying mechanism and a multiplex copying mechanism have been developed. In order to configure the double-sided copying mechanism and the multiplex copying mechanism, a stock portion generally called an intermediate tray is conventionally provided, and a predetermined number of sheets after copying is temporarily provided on the first surface of the intermediate tray. A method is used in which the sheet is stored, and then the sheet is fed again to the copying section, and the first side is duplicated on the back side of the copied sheet (hereinafter referred to as a re-feed sheet) or on the same side. There is. Then, this method is extremely effective when making a large number of copies. Further, a predetermined sheet conveying path is set according to each mode when the re-feed sheet is stored in the intermediate tray, and in the double-sided copy mode, the re-feed sheet is placed on the intermediate side with its copied image side facing up. The tray is set to be stored in the tray, and in the multiple copy mode, the re-feed sheet is stored with the copied image side facing down.

The conventional copying machines M ₁₊ , M ₂ and M will be described below with reference to FIG.
The transport path of No. ₃ will be described.

In the case of the first conventional copying machine M ₁ , as shown in FIG. 5A, the sheet S fed from the sheet feeding section A is copied on the first side by the copying section B, and the fixing section C is copied. Pass through. Then, in the flat copy mode, the first flapper D ₁ moves to the discharge conveyance path P.
_The sheet S, which has been switched to the ₂ side and is fixed, has a discharge conveyance path P.
₁ is conveyed and is discharged to the paper discharge unit E. In the double-sided or multi-copy mode, the first flapper D ₁ is switched to the first sheet conveyance path P ₂ side and the fixed sheet S is fixed.
Is conveyed through the first sheet conveying path P ₂ to reach the second flapper D ₂ . Then, in the double-sided copy mode, the second flapper D ₂ is switched to the second sheet transporting path P ₃ side, and the sheet S is transported through the second sheet transporting path P ₃ so that the image surface faces up. And is stored in the intermediate tray T. Furthermore,
In the multiple copy mode, the second flapper D ₂ is set to the third flapper D ₂ .
The sheet S is switched to the sheet transporting path P ₄ side, is transported through the third sheet transporting path P _4, and is stored in the intermediate tray T with the image side facing down. In any of the double-sided copy mode and the multiplex copy mode, the sheet S stored in the intermediate tray T is re-fed toward the copying section B through the sheet re-sending path P ₅ and copied on the back surface or the same surface. And passes through the fixing section C. Therefore, the first flapper D ₁ is switched to the discharge conveyance path P ₁ side, and the sheet S on both sides or after the multiple copying is discharged to the discharge section E.

Further, in the case of the second conventional copying machine M ₂ , as shown in FIG. 5 (b), the sheet S fed from the sheet feeding section A is fed.
Is copied on the first side by the copying unit B and passes through the fixing unit C. Then, in the single-sided copy mode, the first flapper D ₃ is switched to the discharge / conveyance path P ₆ side, and the fixed sheet S is conveyed in the discharge / conveyance path P ₆ by the forward / reverse rotation roller pair R ₁ that rotates normally. And is discharged to the paper discharge section E. In the double-sided copy mode, the flapper D ₃ is switched to the discharge / conveyance path P ₆ side, and the fixed sheet S is rotated in the forward / reverse rotation roller pair R _{1 so that the} discharge / conveyance path P ₆ is directed toward the discharge section E. When the sheet is conveyed and the trailing edge of the sheet is detected by the sensor X ₁ , the forward / reverse rotation roller pair R ₁ reversely rotates, and the sheet S starts from the trailing edge of the sheet S and moves toward the first sheet conveying path P ₇ and the third sheet conveying path P ₇ . The sheet is conveyed through the sheet conveying path P ₉ and is stored in the intermediate tray T with its image side facing up. Furthermore, if the multiple copy mode, the flapper D ₃ is switched to the second sheet conveying path P ₈ side fixing sheets S is a second sheet conveying path P ₈ and the third sheet conveying path P ₉ The sheet is conveyed and stored in the intermediate tray T with its image side facing down. The sheets S stored in the intermediate tray T are fed to the sheet re-feeding path P as in the case of the first copying machine M _1.
5 is conveyed and is discharged to the paper discharge unit E.

Further, in the case of the third conventional copying machine M ₃ , as shown in FIG. 5 (C), the sheet S fed from the sheet feeding section A is fed.
Passes through the fixing section C which is copied on the first side in the copying section B.
In the single-sided copy mode, the flapper D ₄ is switched to the discharge / conveyance path P ₁₀ side, and the fixed sheet S is conveyed through the discharge / conveyance path P ₁₀ and is discharged outside the machine and also serves as the intermediate tray T. It is discharged to the part E. Also, in the case of duplex copying mode, as in the case flapper D ₄ is the above-mentioned single-sided copying mode is switched to the discharge conveyance path P ₁₀ side fixing sheets S is conveyed to the discharge conveyance path P _10, the image The paper is stored in the intermediate tray T, which also serves as the paper discharge unit E with its surface facing upward. Further, in the multiple copy mode, the flapper D ₄ is switched to the first and second sheet conveying paths P ₁₁ and P ₁₂ side, and the fixed sheet S is conveyed through the first sheet conveying path P _11. hand,
Is conveyed to the reverse conveying path P ₁₃ in normal and reverse rotation roller pair R ₂ in a normal direction, the trailing edge of the sheet is detected by the sensor X _2, and reversed forward reverse roller pair R _2, sheet S is its rear end At the top, the sheet is conveyed through the second sheet conveying path P ₁₂ and the discharge conveying path P _10, and is stored in the intermediate tray T with its image side facing down, and is stored in the intermediate tray T with its image side facing down. It is stored. Then, the sheets S stored in the intermediate tray T are transported through the sheet re-sending path P ₅ , pass through the copying section B and the fixing section C, and are provided outside the apparatus, as in the case of the first copying machine M _1. The sheet is discharged to the sheet discharge section E which is also used as the intermediate tray T.

(C) Problems to be Solved by the Invention By the way, in the above-mentioned first conventional copying machine M ₁ , the sheet conveying path from the fixing section C to the intermediate tray T is very long,
The guide member that constitutes the sheet conveying path is large, and the number of assembling steps is large, which causes a high cost. Further, since the sheet conveying path is long, there are many places for sheet jam processing, and operability is poor.

Further, in the second copying machine M ₂ , the sheet S temporarily comes out of the machine in the double-sided copying mode. Therefore, there is a possibility that the operator may erroneously grip the sheet S, and if it is gripped, it may cause a jam. Further, since the sheet S may once come out of the machine, it is difficult to mount an application such as a sorter or a finisher on the paper output unit E.

Further, in the third of the copying machine M _3, to the intermediate tray T of the paper output unit E serves is provided outside the apparatus, the width of the copying machine is increased, further sorter to the same discharge unit E, or It is difficult to install applications such as finishers.

(D) Means for Solving the Problem The present invention is intended to solve the above-mentioned problems, and a sheet reversal conveyance path is arranged below the intermediate tray, and the intermediate tray has The member serving as the lower surface is an upper sheet guide surface in the sheet reverse conveyance path.

(E) Action Based on the above-mentioned configuration, when the sheet selected to be inverted is carried into the sheet inversion conveyance path located below the intermediate tray, the sheet is transferred to the lower surface of the sheet inversion conveyance path intermediate tray. Is guided by the member to be conveyed.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 3, a copying machine M for performing double-sided copying and multiplex copying according to the present embodiment has a copying section 5 having a photoconductor 6 at a substantially central portion of the main body of the copying machine and an original document at an upper portion of the copying machine. Stand 2
Is equipped with. A scanning system 3 is provided below the document table 2.
Is provided, and a sheet feeding unit 11 including sheet cassettes 7 and 9 and a manual feed stand 10 is configured on the right side of the machine body. The manual feed stand 10 and the sheet cassettes 7 and 9 are provided with paper feed rollers, respectively. 12, 13, 15 are provided. A registration roller 19 and a transfer device 20 are arranged near the photoconductor 6, and the conveyor belt 2 is provided.
1. The fixing unit 22 is arranged, and the first flapper 23 is provided downstream of the fixing unit 22. The flapper 23 is provided in two directions of the discharge conveyance path Pa side or the re-feed conveyance path Pb side. Can be switched. A transport roller pair 25 is provided downstream of the discharge transport path Pa, and a discharge tray 26 is disposed outside the machine downstream of the transport roller pair 25. Further, the re-feeding / conveying path Pb is provided with a pair of conveying rollers 27, and a second flapper 29 is arranged downstream of the re-feeding / conveying path Pb. Then, the second flapper 2
As shown in detail in FIG. 1, reference numeral 9 denotes a curved outer guide G ₁ and upper and lower inner guides G ₂ , G ₃ , respectively.
The first conveyance path Pc and the third conveyance path Pe are formed at the position indicated by the chain line, and the second conveyance path is formed at the position indicated by the solid line.
So that each of the transport paths Pd is formed.
It is switched to the c, Pd, Pe side. Further, a transport roller pair 2, a switching guide 33 and a transport roller pair 35 are disposed downstream of the second transport path Pd, and the switching guide 3
3 can be switched in two directions. Further, the switching guide 33
An intermediate tray 36 is disposed below the intermediate tray 36. The intermediate tray 36 has an upper surface 36a formed by a large number of projections 51 ... And a lower surface 36b formed by a large number of projections 52 ... (See Figure 2).

On the other hand, facing the intermediate tray 36, the sheet reverse conveyance path 30
As shown in FIG. 1, the sheet reversing / conveying path 30 is provided with an outer guide G ₁ and a lower inner guide G.
_3, the downstream portion 30b, which is composed of the upstream portion 30a, the lower surface 36b of the intermediate tray 36, and the bottom floor member 50 of the copying machine M, and is positioned substantially horizontally below the intermediate tray 36.
Consists of. In addition, the downstream portion 3 of the sheet reversal conveyance path 30.
0b is configured without using a unique guide member. A reversing roller pair 31 that rotates in the normal and reverse directions is disposed on the upstream side 30a of the reversing conveyance path 30, and a reversal sheet detection sensor X is provided upstream of the reversing roller pair 31 and the second flapper 29 is provided. And these sheet reversal conveyance path 30, reversal roller pair 31, and reversal sheet detection sensor X
Constitutes sheet reversing means, and reverses and conveys the sheet to be retransmitted to the copying section 5 toward the intermediate tray 36. And
When the second flapper 29 is switched to the first conveyance path Pc and the third conveyance path Pe side and the sheet S is carried into the sheet reversal conveyance path 30 through the first conveyance path Pc, the sheet S is conveyed. Is clamped by a pair of reversing rollers 31 that rotate in the normal direction and conveyed to the downstream portion 30b of the sheet reversing conveying path 30. At this time, since the member that becomes the lower surface 36b of the intermediate tray 36 that constitutes the sheet reversing / conveying path 30 is composed of the large number of ridges 52 ... The contact area with the leading end is small, the transport resistance between the leading end of the sheet S and the lower surface 36b of the intermediate tray 36 is low, and the sheet S can be carried in smoothly. In particular, even when the leading end of the sheet S is curled, the sheet S can be carried in smoothly. Then, when the sheet S is conveyed to the downstream portion 30b of the sheet reversal conveyance path 30 and the rear end of the sheet S is detected by the reversal sheet detection sensor X, the reversal roller pair 31 is rotated in the reverse direction to sandwich the sheet. The S is switched back and is transported to the third transport path Pe. Therefore,
The sheet S is transported by the transport roller pair 32, the switching guide 33, and the transport roller pair 35, inverted so that the image surface thereof faces upward, and stored in the intermediate tray 36.
At this time, since the member serving as the upper 36a of the intermediate tray 36 is composed of the large number of ridges 51 ... As described above, the contact area with the stored sheet S is small, and the sheet S and the tray upper surface 36a are small. The conveyance resistance between the intermediate tray 36 and the intermediate tray 36 is low, and the sheet storage property and stacking property of the intermediate tray 36 are good. A re-feeding roller 45 and a separating roller 46 are provided on the downstream side of the intermediate tray 36 shown in FIG. 1, and the sheets S stored on the intermediate tray 36 are sequentially conveyed from the bottom one by one. It will be re-delivered.

In the copying machine M having the above-described configuration, when a document is first placed on the document table 2 and a copy start button (not shown) is operated, the image described on the document is rotated by the scanning system 3 to rotate the photosensitive member in the copying section 5. It is developed as a toner image on the body 6. Then, the sheet S is fed from the sheet supply unit 11 such as the sheet cassette 7 or 9 or the manual feed tray 10 to a predetermined sheet feeding roller 12 or 1.
When it is conveyed in synchronization with the copying section 5 through the registration rollers 19 via the rollers 3, 15, the toner image is transferred onto the upper surface of the sheet S in the transfer device 20, and the sheet S thus copied is conveyed by the conveying belt. It is fixed by the fixing unit 22 via 21 and is further conveyed to various subsequent mechanisms. If only one side needs to be copied, the sheet S passes through the pair of transport rollers 25 by the guiding action of the first flapper 23 that is switched to the side of the discharge / transport path Pa, and then the sheet S is discharged.
A paper discharge tray 26 provided outside the copying machine
Stacked on top. Then, when double-sided copying or multiple copying is required, the sheet S passes through the pair of conveying rollers 27 by the guiding action of the first flapper 3 which is in the switching state on the side of the re-feeding / conveying path Pb, and then the sheet S / re-feeding / conveying path Pb. Is conveyed toward the second flapper 29. Here, when performing double-sided copying, the sheet S is carried into the sheet reversing conveyance path 30 by the second flapper 29 switched to the first conveyance path Pc side and the third conveyance path Pe side. As described above, the sheet is switched back by the pair of reversing rollers 31 that rotate in the normal and reverse directions, is subjected to the reversing action, and is conveyed through the third conveying path Pe. In the case of a large sheet, the state shown by the solid line in FIG. (See FIG. 1), the changeover guide 33 guides the sheets, and the sheets are sequentially stacked on the intermediate tray 36 with the image surface upward through the lower side of the guide 33. Switching guide 33 in the state shown by the chain line
The sheet is guided on the upper surface of the sheet and is further sequentially accumulated on the intermediate tray 36 through the pair of conveying rollers 35.

Then, when performing multiple copying, the second transport path Pd
By the guiding action of the second flapper 29 switched to the side, the second flapper 29 directly conveys the second conveyance path Pd, and the conveyance roller pair 32 is conveyed.
After that, the images are sequentially stacked on the intermediate tray 36 with the image surface facing down, as in the case of the above-mentioned double-sided copying. In this way, after a predetermined number of single-side copied sheets are stacked on the intermediate tray device 36, the second surface of the original document is placed on the document table 2 or an original document for multiple copying is placed. When the copy start button is operated, the re-feed roller 45 and the separation roller 46 in the intermediate tray 36 are driven this time,
The sheets accumulated on the intermediate tray 36 are conveyed to the copying section 5 again from the bottom through the pair of conveying rollers 37, the sheet re-feeding path Pf, the registration rollers 19 and the like, and in the case of double-sided copying, the back surface of the sheet In the case of multiple copying, the sheets are copied on the same side of the sheet. Therefore, the sheets for which copying has been completed are guided by the first flapper switched to the discharge / conveyance path Pa side and are conveyed so as to be stacked on the tray 26 this time.

Although the sheet reversal conveyance path 30 of the present embodiment is configured to reverse and discharge the sheet S to be retransmitted to the copying section 5 to the intermediate tray 36 at the time of double-sided copying, the present invention is not limited to this. It may be a sheet reversing conveyance path for reversing and ejecting sheets on both sides or sheets that have undergone multiple copying. That is, in the copying machine M ', as shown in FIG.
Is in the position shown by the solid line, the paper ejection tray 6
It is discharged to 2. Further, when the flapper 61 is at the position shown by the chain line, the sheet is conveyed through the first sheet conveying path 63 and is conveyed into the sheet reversing conveying path 66 disposed below the intermediate tray 65, and rotates normally. When the reverse roller pair 67 further conveys the sheet reverse conveyance path 66, and the rear end is detected by the sensor 69, the reverse roller pair 67 reverses the rotation and switches back, and the second sheet conveyance path 70 conveys the sheet. The sheet is inverted and discharged onto the sheet discharge tray 62.

(G) Effect of the Invention As described above, according to the present invention, the sheet reversing conveyance path is arranged below the intermediate tray, and the member serving as the lower surface of the intermediate tray is guided to the upper side of the sheet reversing conveyance path. As the surface is configured to guide the conveyed sheet to the sheet reversal conveyance path, it is not necessary to provide an upper guide member for the sheet reversal conveyance path, which reduces the number of guide members, and thus the number of parts and the assembly process. Therefore, the cost can be reduced, and the device can be downsized by saving space.

Further, when the member serving as the lower surface of the intermediate tray is composed of a plurality of ridges extending in the sheet conveying direction, the curled sheet is easily and reliably guided and conveyed, and the reliability of the apparatus is improved.

Further, when the sheet reversing / conveying path is provided inside the apparatus, it does not prevent the sheet separating apparatus (sorter) or the binding / folding apparatus (finisher) from being attached to the apparatus.

[Brief description of drawings]

FIG. 1 is a side view showing a sheet inversion conveyance path and an intermediate tray of a copying machine according to a first embodiment of the present invention, FIG. 2 is an oblique view thereof, and FIG. 3 is a copying machine according to the first embodiment. Schematic side view of
FIG. 4 is a schematic side view of a copying machine of another embodiment, and FIGS. 5 (a) to 5 (c) are schematic side views showing different sheet reversing conveyance paths of a conventional copying machine. M, M '... Image forming apparatus (copying machine), 30 ... Sheet reversing conveyance path, 36 ... Intermediate tray, 36b ... Lower surface of intermediate tray, 52.

Claims (2)

[Claims] 1. An intermediate tray for accommodating sheets to be re-fed to an image forming section when a double-sided mode for forming images on both sides of a sheet or a multiplex mode for forming images on the same side of sheets is selected in the apparatus. In the image forming apparatus including a sheet reversing conveyance path for reversing the conveyed sheet, a member that is the lower surface of the intermediate tray, the sheet reversing conveyance path is disposed, and is a lower surface of the intermediate tray. An image forming apparatus having an upper sheet guiding surface in the sheet reversal conveyance path. 2. The image forming apparatus according to claim 1, wherein the member serving as the lower surface of the intermediate tray comprises a plurality of protrusions extending in the sheet conveying direction.