JPH0639310B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention is to transfer a sheet-shaped transfer material (sheet material) such as a plurality of paper pieces to a desired pattern for the first time (for example, the first surface),
Characters are printed, these transfer materials are stacked in a predetermined position in the apparatus, and then a desired pattern is displayed for the second time (for example, the second surface).
The present invention relates to a double-sided or multiple image forming apparatus (hereinafter, referred to as a printing apparatus at the end) for printing characters and the like.

(B) Conventional technology Since the double-sided printing apparatus prints on both the first side and the second side in one image forming unit, if printing is performed on the first side of the transfer material, these transfer materials are not printed. Printing cannot be performed on the second side unless it is reversed. Therefore, it is necessary to reverse the transfer material printed on the first surface and stack the transfer material at a predetermined position in the apparatus.

Conventionally, an intermediate tray is used for stacking the transfer material printed on the first side, and the transfer material is sent to the intermediate tray or the image forming unit again. Then, the transfer material is inverted and stacked on this intermediate tray.

In order to reversely supply the transfer material to the intermediate tray, the first
The conveying means for conveying the transfer material having the surface printed thereon must be located above the intermediate tray, and the leading edge of the carrying means must be located above the leading edge of the intermediate tray.
Then, when the transfer material is fed to the intermediate tray, the leading end of the transfer material moves downward and is fed in a direction substantially opposite to the transport direction of the transport means.

Of the transfer materials fed into the intermediate tray, the first transfer material is rapidly advanced by the re-feeding means and stands by in the re-feeding path for printing the second surface.

(C) Problems to be solved by the invention However, since the rear edge of the transfer material waiting in the re-feeding path in the re-feeding progress direction is positioned in the intermediate tray depending on the size of the transfer material. , There are the following problems. Such a state is shown in FIG.

The rear edge 1a of the first transfer material 1 in the re-feeding proceeding direction is closer to the intermediate tray 2 than the re-feeding roller pair 3 provided at the leading edge of the intermediate tray 2 is by a distance L as shown in the figure. It is protruding. Now, it is assumed that the position on the intermediate tray 2 where the front edge 5b of the second transfer material 5 sent to the intermediate tray 2 by the above-mentioned conveying means falls and comes into contact first is P.
When the front end 5b of the second transfer material 5 in the re-feeding advance direction falls, the rear end 5a of the second transfer material 5 in the re-feeding advance direction has already been re-feeded in the intermediate tray 2. It is located on the opposite side of the roller pair 3. Further, the front edge 6b of the third transfer material 6 in the re-feeding advance direction also falls at point P.

When the distance between the point P and the re-feed roller pair 3 is larger than the distance L, the front end edge 5b of the second transfer material 5 dropped on the intermediate tray 2 in the re-feed progress direction is already in the re-feed path. It is in contact with the rear edge 1a of the first transfer material 1 which is waiting inside in the re-feeding advance direction. In such a state, since the first transfer material 1 and the second transfer material 5 form the same surface, the third transfer material 6 sent to the intermediate tray 2 has the first transfer material 1 and the second transfer material 5 transferred to the intermediate tray 2. It slides on the upper surface of the material 5, and as shown in FIG. 2, it stops in a state where the front end edge 6b of the re-feeding advancing direction reaches the re-feeding roller pair 3.

Next, when the printing on the second side is started and the first transfer material 1 is fed from the re-feeding path to the image forming portion, the second transfer material 5 is fed in advance and the re-feeding path is being fed. I have to wait. However, since the front end edge 6b of the third transfer material 6 in the re-feed progress direction reaches the re-feed roller pair 3,
Although the transfer material 5 has to be sent by the re-feed roller pair 3, the third transfer material 6 is sent.
Alternatively, the second transfer material 5 and the third transfer material 6 are superposed and sent.

As a result, the pages may be swapped or printed across two transfer materials.

Therefore, an object of the present invention is to provide a double-sided printing device that can reliably perform printing without changing the feeding order when the transfer material is re-fed for the second printing (second surface). I am trying.

(D) Means for Solving Problems In order to achieve the above object, the double-sided printing device according to the present invention prints on the first surface and the second surface of the sheet material in the same image forming unit. Therefore, it has an intermediate tray for storing the printed sheet material on the first side, and an intermediate feeding means for conveying the sheet material to the intermediate tray, and an intermediate tray for printing on the second side. In a double-sided printing apparatus having a sheet material inside of which is pre-fed to a re-feeding path and having means for waiting the pre-fed sheet material in the re-feeding path,
When the rear edge of the standby sheet material in the re-feed advancing direction exists in the intermediate tray, the rear edge of the re-feed advancing direction is fed to the intermediate tray from the intermediate feeding means. The sheet material is located rearward of the front edge of the sheet material in the re-feed advance direction.

(E) Action The first sheet material printed on the first surface and sent to the intermediate tray is pre-fed and stands by in the re-feed path. Then, the second sheet material printed on the first surface is sent to the intermediate tray. At this time, the front end edge of the second sheet material in the re-feeding advance direction is located in front of the rear end edge of the first sheet material remaining in the intermediate tray in the re-feeding advance direction. That is, the first sheet material and the second sheet material are in a partially polymerized state. Next, when the third sheet material is fed to the intermediate tray, the third sheet material is stacked on the second sheet material. After that, the succeeding sheet material is stacked on the preceding sheet material.

When the first sheet material is re-fed to the image forming unit for printing on the second side, the second sheet material is pre-fed and stands by in the re-feeding path. At this time, since the second sheet material is superposed on the first sheet material, the second sheet material surely follows the first sheet material. Then, the third sheet material follows the second sheet material.

(F) Embodiment Hereinafter, the double-sided printing apparatus according to the present invention will be specifically described based on the embodiment shown in FIG.

The double-sided printing device M is configured by combining an upper machine body 11 and a lower machine body 12.

The deck 13 is attached to one side surface of the upper machine body 11, and transfer materials (sheet materials) S such as paper pieces and OHP sheets are stacked and stored in the upper deck 13. Above the transfer material S, the pickup roller 15
It is pressed against and installed. An image processing device 16 is attached to the upper part of the upper body 11, and the image processing device 16
The original to be printed is placed on the double-sided printing device M
In addition to the input of the instruction regarding the printing mode in (1), the image processing apparatus 16 outputs the instruction to each unit of the screen printing apparatus M as a signal.

Inside the machine body 11, there is housed an image forming section 21 including a photosensitive drum 17, a main conveying means 19 composed of an endlessly circulating belt, and a fixing roller pair 20. A registration roller pair 22 is provided immediately in front of the image forming unit 21, and a first conveyance roller pair 23 is provided between the registration roller pair 22 and the pickup roller 15 and is provided in the upper deck 13. The transfer material S is sent from the first conveying roller pair 23 to the image forming unit 21 via the registration roller pair 22. A second pair of transport rollers 25 is provided in front of the image forming unit 21.

A vertical transfer unit 26 is provided on the other side surface of the upper machine body 11. The vertical transport unit 26 is provided with a swingable deflector 27 following the second transport roller pair 25, a relay transport roller pair 29 is provided below the deflector 27, and a third transport roller pair 30 is provided above. Has been. Further, a discharge roller pair 31 is provided diagonally above the third transport roller pair 30, and the transfer material S discharged by the discharge roller pair 31 outside the vertical transport unit 26 at a position facing the discharge roller pair 31. An accommodating tray 32 for accommodating is stored.

On the other hand, a lower deck 35 is attached to one side surface of the lower machine body 12, and in the lower deck 35, like the upper deck 13, transfer materials S such as paper pieces and OHP sheets are stacked and stored. A pickup roller 36 is provided above the transfer material S so as to be pressed by the transfer material S. The transfer materials S stored in the upper deck 13 and the lower deck 35 may have the same size or different sizes. A fourth transport roller pair 37 is provided in front of the pickup roller 36, and the registration roller pair 2 is provided in front of the fourth transport roller pair 37.
The transfer path of the transfer material S on the lower deck 35 is determined so that the second deck 2 is positioned, and the distance from the pickup roller 15 to the registration roller pair 22 is equal to the distance from the pickup roller 36 to the registration roller pair 22. ing.

The lower end of the vertical transport unit 26 reaches the lower body 12, and the intermediate tray 39 having the lower end facing the rear end is tilted with the front end facing downward, and is disposed substantially in the center of the lower body 12. It is set up. A refeed roller pair 40 is provided at a position where the front edge of the intermediate tray 39 faces, and a fifth transport roller pair 41, a sixth transport roller pair 42, and a seventh transport roller are provided in front of the refeed roller pair 40. Pairs 43 are sequentially arranged. The fourth conveyance roller pair 43 is provided in front of the fourth conveyance roller pair 43.
The conveyance roller pair 37 is positioned, and the seventh conveyance roller pair 43
The transfer material S sent by is fed again to the image forming unit 21 via the fourth transport roller pair 37. Further, the path from the re-feed roller pair 40 to the fourth transport roller pair 37 is a re-feed path 45, and this re-feed path is between the sixth transport roller pair 42 and the seventh transport roller pair 43. It is bent.

In addition, the fifth conveyance roller pair 41 and the sixth conveyance roller pair 4
2 and between the sixth conveyance roller pair 42 and the seventh conveyance roller pair 43, a sensor 46 for detecting the presence or absence of the transfer material S.
Also, a sensor 47 is provided.

Above the intermediate tray 39, there is a pair of intermediate conveying rollers 49.
And a sub-conveying means 50 composed of a belt that moves endlessly
Is provided. The front end side of the intermediate feeding means 51 is the intermediate tray 3 described above.
It is positioned substantially above the front end side of the sheet feeding device 9, and a feeding roller pair 52 is arranged between the intermediate feeding means 51 and the intermediate tray 39. Further, the intermediate feeding means 51 is arranged on the downstream side of the relay conveying roller pair 29.

Then, the transfer material S sent to the intermediate tray 39 is sent to the re-feed path 45 by the re-feed roller pair 40 and the like, and the sensor 47 detects the front edge portion of the transfer material S in the re-feed progress direction. Then, the re-feeding of the transfer material S is stopped and it stands by in the re-feeding path 45. At the time of this waiting, the rear edge of the transfer material S in the re-feeding progress direction is in the middle. When the transfer material S remains in the tray 39, the transfer material S, which will be described later, is transferred to the intermediate tray 3 at the position of the trailing edge.
The arrangement position of the feed roller pair 52 is determined so that the feed roller pair 52 is located rearward of the front end edge in the re-feeding advance direction when being fed to the sheet 9. Further, the distance from the front edge of the standby transfer material S in the re-feeding advance direction to the image forming portion 21 and the front edge of the transfer material S accommodated in the upper deck 13 and the lower deck 35 in the forward feed direction. From the image forming unit 21
The standby position in the re-feeding path 45 of the transfer material S is determined such that the distance to

In the figure, 55, 56, 57, 59 and 60 are all sensors for detecting the presence or absence of the transfer material S at the position.

Next, the operation will be described.

A desired document is set on the image processing device 16, and the size of the transfer material S, the number of prints, and the like are input through an operation panel (not shown). Depending on the size of the transfer material S, either the transfer material S accommodated in the upper deck 13 or the lower deck 35 is used. Now, assume that the transfer material S accommodated in the upper deck 13 is selected, and the number of printed sheets is 5, so that double-sided printing is performed.

When the start button on the operation panel is operated, the pickup roller 15 starts rotating. Since the pickup roller 15 is pressed against the transfer material S, the uppermost first transfer material S ₁ is fed. The first transfer material S ₁ reaches the registration roller pair 22 via the first transport roller pair 23. At this point, the signal from the sensor 55 temporarily stops, and if the vehicle is skewed, it is corrected and fed to the front image forming unit 21. In the image forming section 21, first, the photosensitive drum 17 is driven by a known laser and laser scanning optical system in the image processing apparatus 16.
The latent image formed on the first
A visible image is formed on the transfer material S ₁ . Then, the main transport means 19
Is sent to the fixing roller pair 20 and fixed there. Further, the second and subsequent transfer materials S are fed at appropriate intervals in the same manner as the first transfer material S ₁ .

The first transfer material S _{1 that} has passed through the fixing roller pair 20 is fed to the deflector 27 by the second conveying roller pair 25.
The deflector 27 is oscillated in advance by a signal for double-sided printing, and is in a position to send the transfer material S to the relay conveyance roller pair 29. Then, the first transfer material S ₁ is the relay conveyance roller pair 2
9 is fed to the lower body 12.

The first transfer material S ₁ fed to the lower machine body 12 is fed to the intermediate tray 39 by the intermediate feeding means 51. At this time, the edge that was on the front side in the feeding direction in advance is fed first, and the first transfer material S ₁ is turned upside down. Therefore, the edge that was on the front side in the feeding direction before that,
At the time of re-feeding, the edge is on the back side in the re-feeding progress direction.

The first transfer material S ₁ sent to the intermediate tray 39 is before the subsequent second transfer material S ₂ is sent to the intermediate tray 39. The pre-feeding is performed by the rotation of the conveying roller pair 42 and the seventh conveying roller pair 43. The first transfer material S ₁ that was previously fed
When the front edge of the sheet before re-feeding is detected by the sensor 47, each roller pair 40, 41, 42, 43 stops and the first transfer material S
₁ waits in the refeed path 45. The rear side end of the first transfer material S _{1 in} the re-feeding progress direction remains in the intermediate tray 39.

Then, the second transfer material S ₂ is fed to the intermediate tray 39, but in the fed state, the first transfer material S ₂ remains in the intermediate tray 39 more than the rear end edge in the re-feeding advance direction. Since the end edge of the transfer material S ₁ is located rearward, the first transfer material S ₁ and the second transfer material S ₂ partially overlap with each other. Subsequent third transfer material S ₃ , fourth transfer material S _4, and fifth transfer material S ₅ are sequentially stacked on the second transfer material S ₂ .

When the printing of the first surface of the fifth transfer material S ₅ is completed, the printing of the second surface of the first transfer material S ₁ is started. Sixth transport roller 4
2. The seventh transfer roller 43 rotates, and the first transfer material S ₁ that has been waiting in the re-feed path 45 is re-fed. The front end of the first transfer material S _{1 in} the re-feeding direction is the fourth transport roller 3
When the sheet is gripped by 7, the sheet is fed to the image forming unit 21 and printed on the second side like the transfer material S stored in the lower deck 35.

When the first transfer material S ₁ is sent out from the re-feeding path 45,
The second transfer material S ₂ is discharged from the intermediate tray 39, and the second transfer material S ₂ stands by in the re-feeding path 45. When the second transfer material S ₂ is sent out from the re-feeding path 45, the third transfer material S 3
The transfer material S ₃ is ejected from the intermediate tray 39, and subsequently re-fed sequentially, and the respective re-feed paths 45 stand by. Moreover, as described above, since a part of the first transfer material S _{1 and} a part of the second transfer material S ₂ are polymerized, the first transfer material S ₁
After being re-fed, the second transfer material S ₂ is surely re-fed, and the same applies to the transfer material S described later.

Then, after passing through the image forming unit 21 and reaching the deflector 27, the deflector 27 is in a state of swinging so as to guide the transfer material S to the upper third conveying roller pair 30, and thus the transfer material S is stored in the storage tray. It is discharged to 32 and sequentially loaded.

If the size of the transfer material S does not extend from the sensor 47 to the sensor 46, the sensor 46 detects that the transfer material S is absent. Therefore, the second transfer is performed after the first transfer material S _1. The material S _{2 is} also fed in advance. In this case, the second transfer material S ₂ is stopped at an appropriate interval from the first transfer material S ₁ , and its rear end in the re-feeding advance direction remains in the intermediate tray 39.

Next, the sheet is pre-fed from the intermediate tray 39, and the re-feed path 4
One specific example of the positional relationship of the transfer material S standing by in 5 will be shown.

Distance from the front edge of the transfer material S waiting in the re-feeding path 45 in the re-feeding advance direction (this position may be the same as the position where the sensor 47 is provided) to the re-feeding roller pair 40. To 280 mm. Further, the distance from the re-feed roller pair 40 to the above-mentioned point P is 80 mm. The length of the transfer material S is 182 mm for the B5 size, 210 mm for the A4 size, and 3 for the B6 size.
65mm and 420mm for A3 size. The remaining length of the transfer material S fed in advance in the intermediate tray 39 (the above-mentioned L) is as shown in Table 1. However, since the size of the transfer material S of B5 size does not extend from the sensor 47 to the sensor 46, the second transfer material S _{1 is} separated by 45 mm from the first transfer material S ₁ .
The transfer material S _{2 is} also preliminarily fed.

As shown in Table 1, the trailing edge of the first transfer material S ₁ (or the second transfer material S ₂ ) in the re-feeding direction is the re-feeding of the second transfer material S ₂ (or the third transfer material S ₃ ). It is located behind the front edge in the feeding direction.

As described above, a double-sided printing apparatus with good workability can be obtained by simply changing the feeding position of the intermediate feeding / feeding means for feeding the sheet to the intermediate tray of the conventional double-sided printing apparatus.

(G) Effect of the Invention As described above, according to the present invention, the sheet material waiting in the re-feeding path has the rear edge in the re-feeding advance direction in the succeeding intermediate tray. When the sheet material waiting in the re-feeding path is sent out from the re-feeding path to the image forming unit, the next succeeding sheet is detected. The material is reliably sent to the refeed path. Therefore, the pages will not be swapped or printed across two sheet materials.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of the double-sided printing device according to the present invention, taken along the traveling direction of the transfer material. FIG. 2 is an explanatory diagram of a problem of the conventional double-sided printing device. 11 ... upper body, 12 ... lower body, 13 ... upper deck, 16 ... image processing device, 17 ... photosensitive drum, 1
9 ... Main transport means, 20 ... Fixing roller pair, 21 ... Image forming section, 22 ... Registration roller pair, 27 ... Deflector, 29 ... Relay transport roller pair, 35 ... Lower deck, 39 ... Intermediate tray, 40 ... Refeed roller pair, 4
5 ... Re-feeding path, 51 ... Intermediate feeding means, 52 ... Feeding roller pair, M ... Image forming apparatus (double-sided printing apparatus), S ... Sheet material (transfer material).

Claims (1)

[Claims] 1. An intermediate tray for storing the sheet material on which the first image formation is performed for forming the same sheet material a plurality of times in the same image forming unit, and the intermediate tray for storing the sheet material. Having an intermediate feeding means for transporting to
An image forming apparatus having means for pre-feeding a sheet material in an intermediate tray to a re-feeding path for forming a second image and for waiting the pre-fed sheet material in the re-feeding path. In the case where the rear edge of the standby sheet material in the re-feed advancing direction exists in the intermediate tray, the rear edge of the re-feed advancing direction is fed from the intermediate feeding means to the intermediate tray. An image forming apparatus characterized in that it is located rearward of a front edge of a succeeding sheet material in the re-feeding advance direction.