JPH03211161A - Image former - Google Patents

Abstract

PURPOSE:To increase the setup area of an image former at time of face-down paper discharging and duplex printing by making a face-up paper discharging tray stowable in a unit body, and making a part of a turnover conveying passage so as to be constituted in a state of having this tray stowed. CONSTITUTION:A sheet P formed with an image on the top by a laser beam printer 1 is discharged onto a paper discharge tray 27 as shown in a broken line by a flapper 25 being shown in the broken line in the case of face-up paper discharging for a single side print. On the other hand, in the case of face-down paper discharging, it is discharged onto a tray 19 by flappers 25, 35 as shown in a full line by way of a guide plate 31 and a paper discharge roller 33. In the case of duplex printing, it passes through each upper and lower surface of the flappers 25, 35 being shown in each of full lines and broken lines and, after having run past between the paper discharge tray 27 shown in the full line and the guide plate 29, is switched back by a turnover roller 30 and then it is conveyed by way of each of turnover conveying passages 27a, 29, 37b, 22 and 24, thus an image is formed in the back.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus capable of forming images on both sides of a sheet.

(B) Conventional technology An example of a conventional laser beam printer is shown in Fig. 4.
In the figure, 2 is a main body of a laser beam printer 1 which is an example of an image forming apparatus, a known process cartridge 3 is disposed in the center of the main body 2, and an image carrier is provided in the lower center of the cartridge 3. A photosensitive drum 4 is provided.

Further, a paper feed cassette 5 is attached to the right side of the main body 2, and the sheets P stored in this paper feed cassette 5 are transferred to a paper feed roller 6.
The sheets are fed one by one in the direction of arrow A by the guide plates 7,
The leading edge of the sheet P is regulated and synchronized with the photosensitive drum 4 , and then reaches the photosensitive drum 4 via the guide plate 9 .
After the developed image formed on the sheet P is transferred to this sheet P,
The image is sent to the fixing device 10.

Then, the image transferred by the fixing device 10 is transferred to the sheet P.
After being fixed, the image is discharged out of the main body 2 along different routes according to commands from the controller.

At this time, if the controller command is for face-up ejection of single-sided printing (the image is ejected with the image on the top side of the sheet P), the flapper 12, which is rotatably mounted around the fulcrum 11, will move as shown by the broken line in the figure. After rotating to the display position, the sheet P is sent out in the direction of arrow C by the reversing roller 13 and is ejected onto the paper ejection tray 14 .

Further, when the command from the controller is for face-down discharge of single-sided printing, the flapper 12 rotates to the position indicated by the solid line in the figure, and the sheet P is moved by the flapper 12, the guide plate 15,
The paper is sent in the direction of arrow B via the intermediate roller 16 and the guide plate 17, and is ejected onto the tray 19 by the ejection roller 18.

Further, when the command from the controller is double-sided printing, the flapper 12 rotates to the position indicated by the broken line in the figure, and the sheet P is sent in the direction of arrow Ell C via the reversing roller 13. However, along the way, the reversing roller 13 reverses, the flapper 12 rotates to the position indicated by the solid line, the sheet P is switched back, and the guide plate 20, intermediate roller 21, guide plate 22, intermediate roller 23
, passes through the guide plate 24, passes through the guide plate 7 again, reaches the registration roller 8, where the image is formed and fixed in the same manner as described above, and then the paper is ejected in response to a face-up or face-down ejection command from the controller. Tray 14
Or it is discharged onto the tray 19. In the above, while the sheet P is being conveyed on the guide plate 24, the upper surface and the lower surface of the sheet P are reversed.

(c) Problems to be Solved by the Invention However, in the above conventional example, in the case of double-sided printing 1 to 1, the paper output tray must be opened in order to form the conveyance path for the sheet P, so the laser beam printer The disadvantage is that the installation area increases.

Therefore, by forming the face-up paper output tray so that it can be stored inside the main body of the apparatus, and by configuring a part of the sheet reversal conveyance path with the paper output tray stored within the main body, the installation area can be increased. An object of the present invention is to provide an image forming apparatus that prevents the above problems.

(d) Means for solving the problem The present invention has been made in view of the above circumstances, and includes:
For example, referring to FIG. 1, there is a paper ejection tray (2
7), and a reversing conveyance path (27a, 29.37a, 37b, 22.24) that forms images on both sides of the sheet (P).
In the image forming apparatus (1), the paper ejection tray (27) is formed to be able to be stored in the main body (2) of the image forming apparatus (1), and is housed in the main body (2). Sometimes, the sheet stacking surface (27a) of the paper output tray (27)
) is the reversing conveyance path (27a, 29.37a, 37b,
22.24) is configured as a part (27a).

(E) Function Based on the above configuration, the image forming device (1) is attached to the sheet (P).
), the image forming side is facing upward, and the sheet is ejected to the paper ejection tray (27), and the sheet (P) with the image formed on one side is transferred to the reversing conveyance path (27a, 29.37a, 37).
b, 22.24), and images are formed on both sides of the sheet (P). When forming images on both sides, the paper ejection tray (27) is connected to the main body (
2), and the sheet stacking surface (27a) of the paper discharge tray (27) is connected to the reversing conveyance path (27a, 29.37a, 3).
7b, 2.2.24) as part of said sheet (P)
is conveyed in reverse to form an image on the back side of the sheet (P).

Note that the reference numerals in parentheses are for illustrative purposes only, and do not limit equivalent configurations.

b) Example The present invention will be described in detail below with reference to the drawings.

In FIG. 1, the same reference numerals are used for members having the same configuration and function as the reference numerals used in FIG. 4 for explaining the conventional example.

1 is a laser beam printer which is an image forming device;
A process cartridge 3 is provided approximately in the center of the main body 2 of the printer 1, and a photosensitive drum 4 on which a toner image is formed is provided at the lower end of the process cartridge 3.

A paper feed cassette 5 containing sheets P is attached to the right side of the main body 2, and a paper feed roller 6 for feeding the stored sheets P is attached to the main body 2.

A guide plate 7 is attached to guide the fed sheet P, and a registration roller 8 is attached to the left end of this guide plate 7.
is provided, the image is transferred to the sheet P via the guide plate 9 while contacting the photosensitive drum 4, the sheet P is further conveyed, and the image is fixed on the sheet P in the fixing device 10. ing.

A flapper 25 is pivotally supported on the main body 2 by a shaft 26. The flapper 25 guides the sheet P conveyed leftward from the fixing device 10 diagonally to the upper left at the position indicated by the solid line and to the left at the position indicated by the broken line.

At the position indicated by the solid line, a paper ejection tray 27, which constitutes a part of the left side wall of the main body 2 and on which sheets P ejected with the image forming side facing upward at the position indicated by the broken line is loaded, is pivoted to the main body 2 by a shaft 28. This paper output tray 2
A guide plate 29 is provided facing inside the solid line position 7, and a reversing roller 30 is provided close to the upper ends of the paper discharge tray 27 and the guide plate 29.

Further, a pair of guide plates 31 are provided inside the guide plate 29, and a conveyance roller 3 is disposed close to the lower end of the guide plate 31.
2 is provided, the upper end of the guide plate 31 is curved to the right,
A paper ejection roller 33 is provided near this tip, and this paper ejection roller 33 ejects the sheet P toward the tray 19 provided on the upper surface of the main body.

A guide plate 34 facing in the vertical direction is provided on the lower inner side of the conveyance roller 32, and on the outside of this guide plate 34, the sheet P is transferred from the position indicated by the broken line to the paper output tray at the position indicated by the solid line.
7 and the guide plate 29, and guides the sheet P to the guide plate 34, the conveyance roller 32, and the guide plate 31 at the position indicated by the solid line.
It is rotatably supported on the main body 2 by.

Further, a guide plate 37a is provided below the inner surface of the paper discharge tray 27 at the position indicated by the solid line, and this guide plate 37a is curved and extends horizontally, and a guide plate 37b is opposed to this guide plate 37a. It is set up.

Then, the intermediate roller 2 is placed on the right end of the guide plates 37a and 37b.
1 is provided, followed by a guide plate 22 and an intermediate roller 23.
Following the intermediate roller 23, a guide plate 24 is provided so that its right side curves upward and guides it into the guide plate 7 and in the direction of the arrow.

Next, the present invention will be explained in detail.

When image formation is commanded, the sheet P is fed from the paper cassette 5 by the paper feed roller 6, and when the leading edge of the sheet P hits the nip portion of the registration rollers 8 and the sheet P is curved, the skew of the sheet P is The rows are corrected, and the toner image is then transferred from the photosensitive drum 4 to the sheet P while being conveyed by the registration rollers 8 in synchronization with the photosensitive drum 4 .

Then, the toner image is fixed onto the sheet P by the fixing device 10.

Thereafter, the following actions are performed according to commands from the controller.

First, in the case of face-up paper ejection for single-sided printing, the flapper 25 rotates around the shaft 26 to take the position shown by the broken line, and the paper output tray 27 rotates around the shaft 28 to take the position shown by the broken line. Become. Then, the sheet P is discharged onto the sheet stacking surface 27a of the paper discharge tray 27 in the direction of arrow C.

Next, in the case of face-down paper discharge for single-sided printing, the flappers 25 and 35 respectively rotate around the shafts 26 and 36 to the positions indicated by solid lines, and the sheet P is guided by the flapper 25, the flapper 35, and the guide plate 34, The paper is transported in the direction of arrow B by the transport rollers 32, guided by the guide plate 31, and discharged onto the tray 19 by the paper discharge reeler 33.

Next, in the case of double-sided printing, the flappers 25 and 35 rotate around the shafts 26 and 36 to the solid line display position and the broken line display position, respectively, and the sheet P is guided to the upper surface of the flapper 25,
Further, it passes under the flapper 35, is fed between the paper output tray 27 and the guide plate 29 at the position indicated by the solid line, is sent in the direction of the arrow, and is once carried out of the machine above by the reversing roller 30. , midway through, the reversing roller 30 reverses, the sheet P switches back, is guided by the paper ejection tray 27, the guide plate 29, and the guide plates 37a and 37b, is conveyed in the direction of arrow E by the intermediate roller 21, and is guided Board 22
The sheet P is guided by the sheet P, is conveyed to the intermediate roller 23, is further guided by the guide plate 24 and reversed, and passes through the registration rollers 8, the photosensitive drum 4, and the fixing device 10 as described above, and an image is formed on the back side of the sheet P. . Thereafter, as described above, the sheets are discharged onto the sheet stacking surface 27a of the paper discharge tray 27 or onto the tray 19.

By doing as described above, in the case of face-down paper ejection, there is no need to open the paper ejection tray 27 for either one-sided printing or two-sided printing, and the printer 1
The floor projected area can be reduced.

Recently, there has been a tendency for more sheets to be ejected face-down, and when double-sided printing is used, the number of sheets P is halved and the stacking height is also halved, so the number of sheets ejected face-down should increase with one duplex print. It is.

On the other hand, there are very few occasions when printing on thick paper, envelopes, etc. that are difficult to eject face-down (hard to pass through a curved conveyance path), so it is not necessary to consider the case of face-up ejection when considering the installation area of the device 1. It is thought that there will be no problem.

Next, another embodiment will be described with reference to FIG.

Members having the same configuration and function as those of the above embodiment are given the same reference numerals, and their explanations will be omitted.

A guide plate 38 is provided in place of the paper discharge tray 27 indicated by the solid line shown in FIG. 1, a guide plate 39 is provided in place of the guide plate 37b, and a removable guide plate 40 is provided in place of the guide plate 37a. Then, this guide plate 40 can be pulled out and set as a paper discharge tray 41 indicated by a two-dot chain line. Furthermore, a guide plate 42 facing in the vertical direction is provided above the conveyance roller 30.

By doing so, in the case of face-up paper ejection, a manual action is added to remove the guide plate 40 for double-sided printing and attach it as the paper ejection tray 41 indicated by the two-dot chain line.

However, since the frequency of face-up paper ejection is extremely low as described above, there is no problem in practical use.

Next, still another embodiment will be described with reference to FIG.

In this embodiment, the guide plate 40 of the other embodiment shown in FIG.
2b, the guide plate 42a is substituted for the guide plate 40, and the guide plate 42b is used as the left side plate of the device 1,
Use as a guide plate during face-up paper ejection.

Note that 43 in the figure indicates the state in which it is used as a paper discharge tray. The above effects are the same as in the other embodiments, but since the guide plates 42b and 42a are connected smoothly, the guiding performance of the sheet P is improved.

(G) Effects of the Invention As described above, according to the present invention, when the paper ejection tray for ejecting sheets with the image facing upward is housed in the main body of the image forming apparatus, the paper ejection tray is Since the sheet stacking surface constitutes a part of the reversing conveyance path, it is possible to avoid an increase in the installation space of the image forming apparatus for face-down printing and double-sided printing, which are extremely frequent.

[Brief explanation of drawings]

Fig. 1 is a sectional side view showing an embodiment of the present invention, Fig. 2 is a sectional side view showing another embodiment, Fig. 3 is a sectional side view showing yet another embodiment, and Fig. 4 is a sectional side view showing a conventional embodiment. FIG. 1 is a cross-sectional side view of a laser beam printer.

Claims (1)

[Scope of Claims] 1. An image forming apparatus comprising: a paper ejection tray that ejects sheets with images formed on the sheets facing upward; and a reversing conveyance path that forms images on both sides of the sheets. A paper tray is formed to be able to be stored in the main body of the image forming apparatus, and when the paper tray is stored in the main body, the sheet stacking surface of the paper ejection tray forms a part of the reversing conveyance path. An image forming apparatus characterized by: