JPH0585639A - Sheet material conveying device for image forming apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] To accurately guide the leading edge of the sheet material fed from the upstream portion to the nip portion of the conveyance roller pair, and to convey the sheet material fed from the downstream portion and passed through the conveyance roller pair. It makes it possible to prevent problems in transportation. [Construction] The conveyance guide 10 is composed of three guides 10A, 30 and 10B on the upper side, the center and the lower side. Then, the downstream end 33 of the central guide 30 is arranged so as to be located on the lower roller 9B side having a smaller surface friction than the nip center line X of the conveying roller pair 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet material conveying device provided in an image forming apparatus such as a printer or a copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus such as a printer or a copying machine that uses a discharge tray as a manual sheet feeding means, an operation of conveying a sheet material fed from an upstream portion to a downstream side and an operation from a downstream portion A pair of transport rollers that selectively transports the fed sheet material to the upstream side is provided as sheet material transporting means. And, this sheet material conveying means is usually
It has a conveyance guide for guiding the leading end of the sheet material fed from the upstream portion to the nip portion of the pair of conveyance rollers.

8 to 10 show a printer which uses a paper discharge tray as a manual paper feeding means. Here, FIG. 8 shows a state in which the sheet material S1 in the paper feed cassette 1 is fed (a state in which the sheet material S1 is fed from the upstream portion). Further, FIG. 9 shows the sheet material S2 from the discharge tray 2.
Shows the state in which the sheet is manually fed (the sheet material S2 is fed from the downstream portion). Further, FIG. 10 shows a state in which the sheet material S2 manually fed from the paper discharge tray 2 is temporarily stopped on the paper feed cassette 1.

A print head 7 for printing on the sheet materials S1 and S2 by displacing liquid droplets while moving in the paper width direction along the guide rails 5 and 6 is provided at substantially the center of the printer body 3. ing. And, on the upstream side thereof, a conveying roller pair 9, a conveying guide 10, and a paper feeding roller 11 are sequentially arranged. The surface of the upper roller 9A of the conveying roller pair 9 is made of rubber and has a large surface friction. The lower roller 9B of the conveying roller pair 9 is made of metal, resin, or the like, and has a small surface friction. On the other hand, a paper discharge roller pair 12 is arranged on the downstream side of the print head 7.

A sheet feeding cassette 1 loaded with sheet materials S1 is attached to one side (right side in the figure) of the printer body 3 (it can be pulled out in the direction of arrow A as shown in FIG. 8), and the like. The paper discharge tray 2 is attached to the side (left side in the drawing).

The transport roller pair 9 is the paper feed cassette 1 at the upstream portion.
The operation of transporting the sheet material S1 fed from the downstream side and the operation of transporting the sheet material S2 manually fed from the downstream side discharge tray 2 to the upstream side are selectively performed.
When the sheet material S1 fed from the sheet feeding cassette 1 is conveyed, the upper roller 9A of the conveying roller pair 9 rotates clockwise and the lower roller 9B rotates counterclockwise. When the sheet material S2 manually fed from the paper discharge tray 2 is conveyed, the upper roller 9A of the conveying roller pair 9 rotates counterclockwise and the lower roller 9B rotates clockwise.

The transport guide 10 comprises an upper guide 10A and a lower guide 10B fixed to the printer body 3, and the leading end of the sheet material S1 fed from the paper feed cassette 1 is fed to the nip portion 13 of the transport roller pair 90. (See FIG. 8).

A lever 16 for detecting the presence / absence of the sheet materials S1 and S2 is attached to the step portion 15 provided in the sheet passing area of the sheet discharging roller 12 (see FIG. 9). This lever 1
6 is capable of swinging in the vertical direction about the support shaft 17, and the rear end is normally pulled downward by the coil spring 19 so that the arcuate portion 16A at the leading end is located more than the nip portion of the discharge roller pair 12. It is stationary at a slightly higher position. Therefore, when the leading edge of the sheet material S1 fed from the paper feed cassette 1 or the sheet material S2 manually fed from the paper ejection tray 2 is sandwiched in the nip portion of the paper ejection roller pair 12, the arc portion of the lever 16 is formed. 16A is a coil spring 19 centered on the spindle 17.
Swing down against. As a result, the photo sensor (not shown) is shut off, and the paper present signal is output.

A guide plate 20 for manual paper feeding is attached to the paper discharge tray 2. The guide plate 20 is attached to the discharge tray 2 so as to be rotatable in the up-down direction about a support shaft 21. A plunger 22 is connected to the free end 20A side of the guide plate 20 outside the paper passing area (see FIG. 9).
reference). When the plunger 22 is turned on (energized), the free end 20A of the guide plate 20 moves upward to a position facing the nip portion of the paper discharge roller pair 12 as shown in FIG.
When the switch 2 is turned off, the free end 20A of the guide plate 20 moves downward by its own weight to a position parallel to the paper discharge tray 2 as shown in FIG.

The printer is provided with a cassette paper feed mode switch and a manual paper feed mode switch (not shown). Then, when the cassette sheet feeding mode is selected, the pair of transport rollers 9 is in a state of transporting the sheet material S1 fed from the upstream sheet feed cassette 1 to the downstream side, and the pair of sheet discharge rollers 12 discharges the sheet. Ready to move. At this time, the guide plate 20 on the paper discharge tray 2 has returned to the state shown in FIG. On the other hand, when the manual paper feed mode is selected, the guide plate 20 on the paper discharge tray 2 is in the upper dynamic state shown in FIG.

Next, the operation of the printer in the cassette paper feed mode and the manual paper feed mode will be described.

FIG. 8 shows the case where the cassette paper feed mode is selected. When the cassette paper feed mode switch is turned on, the paper feed roller 11 rotates clockwise and the sheet material S1 in the paper feed cassette 1 Be delivered. The sheet material S1 is used as the upper guide 10A and the lower guide 10 of the conveyance guide 10.
By B, the tip thereof is guided to the nip portion 13 of the transport roller pair 9. The sheet material S1 is further fed by the sheet feeding roller 11 even after the leading edge of the sheet material S1 hits the nip portion 13, and the conveyance guide 10
To form a loop in the space. Next, the sheet material S1 is transported to the downstream side by the transport roller pair 9, and printing is performed by the print head 7 in the printing unit 23. After that, the sheet material S1 is discharged onto the discharge tray 2 outside the machine via the discharge port 25 by the discharge roller pair 12.

FIG. 9 shows the case where the manual sheet feeding mode is selected. When the manually fed sheet material S2 is inserted into the printer main body 3 along the upwardly moving guide plate 20, the leading edge of the sheet material S2 is removed. The sheet hits the nip portion of the pair of sheet discharging rollers 12. As a result, the circular arc portion 16A of the lever 16 swings down, and a photo sensor (not shown) outputs a paper present signal. The paper discharge signal causes the paper discharge roller pair 12 and the carry roller pair 9 to rotate in the reverse direction, so that the sheet material S2 manually fed from the paper discharge tray 2 at the downstream portion is carried to the upstream side.
Therefore, the sheet material S manually fed from the guide plate 20
The sheet 2 is conveyed to the upstream side by the paper discharge roller pair 12 and then conveyed to the upstream side by the conveyance roller pair 9. When the sheet material S2 passes through the pair of transport rollers 9, the sheet material S2 is guided by the upper guide 10A and the lower guide 10B of the transport guide 10, and as shown in FIG. Be guided between.

When the sheet material S2 manually fed from the guide plate 20 of the paper discharge tray 2 is conveyed to the position shown in FIG. 10, it is temporarily stopped in that state. At this time, the sheet material S2
The trailing edge of the trailing edge passes through the printing section 23 and is located at a position where it is nipped by the nip portion 13 of the pair of transport rollers 9. In order to determine the rear end position of the sheet material S2, for example, counting may be started at the time when the rear end of the sheet material S2 passes through the lever 16, and the conveyance roller pair 9 may be stopped after a predetermined count. ..

After the temporary stop, when a paper feed (printing) start signal is issued, the transport roller pair 9, the print head 7, and the paper discharge roller pair 12 operate in the same manner as in the cassette paper feed mode, and the guide plate. 20 returns to the down state. Therefore, the manually fed sheet material S2 is printed by the printing unit 23 and then discharged onto the paper discharge tray 2 as in the cassette paper feed mode.

[0016]

By the way, in the above printer, the upper guide 10A and the lower guide 10B of the conveyance guide 10 are configured such that the conveyance roller pair 9 feeds the sheet material S1 fed from the paper feed cassette 1 at the upstream portion. When the sheet material S2 is conveyed to the downstream side, the leading end of the sheet material S2 is guided to the nip portion 13 of the conveying roller pair 9, and the conveying roller pair 9 feeds the sheet material S2 manually fed from the discharge tray 2 at the downstream portion to the upstream side. When the sheet is conveyed, it has a function of guiding the sheet material S2 having passed through the pair of conveying rollers 9 between the sheet feeding roller 11 and the uppermost sheet in the sheet feeding cassette 1.

However, as in the conventional example, the transport guide 10
In the state where the upper guide 10A and the lower guide 10B of the printer 10 are brought close to the nip portion 13 of the pair of transport rollers 9,
On the other hand, when it is fixed, the leading edge of the manually-supplied sheet material S2 that has passed through the pair of transport rollers 9 may be caught by the leading ends of the upper guide 10A and the lower guide 10B, resulting in poor transport. In particular, when the tip of the sheet material S2 is curled, it is easily caught.

This problem can be solved by separating the upper guide 10A and the lower guide 10B from the nip portion 13 of the conveying roller pair 9, but on the other hand, the upper guide 10A and the lower guide 10B do not move the tip of the sheet material S1. Transport roller pair 9
It will not be possible to accurately guide it to the nip portion 13.

Therefore, the present invention has been made in view of the above circumstances, and when the conveying roller pair conveys the sheet material fed from the upstream portion to the downstream side, the leading end of the sheet material is conveyed to the conveying roller pair. Can be accurately guided to the nip portion of the sheet, and when the conveying roller pair conveys the sheet material fed from the downstream portion to the upstream side, the sheet material passing through the conveying roller pair can be smoothly introduced. An object of the present invention is to provide a sheet material conveying device for an image forming apparatus.

[0020]

According to the present invention, an operation of conveying a sheet material (S1) fed from an upstream portion to a downstream side,
The sheet material (S2) fed from the downstream part is conveyed to the upstream side by a pair of conveying rollers (9), and the leading end of the sheet material (S1) fed from the upstream part is conveyed. The present invention relates to a sheet material conveying device of an image forming apparatus, which comprises a conveying guide (10) for guiding the nip portion (13) of a roller pair (9).

In order to achieve the above-mentioned object, the present invention comprises the conveying roller pair (9) comprising a roller (9A) having a large surface friction and a roller (9B) having a small surface friction, and the conveying guide (9). 10) for the upper, middle, and lower 3
It consists of two guides (10A, 30, 10B), and
The downstream end (33) of the central guide (30) is located closer to the roller (9B) having a smaller surface friction than the nip center line (X) of the conveying roller pair (9). Is.

[0022]

According to the above construction, by providing the central guide (30), the sheet material (S1) fed from the upstream portion is provided.
It is possible to separate the path of the sheet material (S2) fed from the downstream portion at the transport guide (10) portion.

For example, the sheet material (S1) fed from the upstream portion is fed with the central guide (30) and the lower guide (10B).
The sheet material (S2) fed from the downstream portion can be passed between the central guide (30) and the upper guide (10A).

Therefore, the upper guide (10A), which does not serve as a path for the sheet material (S1) fed from the upstream portion, does not have to be close to the nip portion (13) of the conveying roller pair (9), and the nip portion (13) ) Can be placed away from.

As a result, the sheet material (S2) that has passed through the pair of conveying rollers (9) is guided without being caught by the upper guide (10A).

Further, the sheet material (S
The tip of 1) has a central guide (30) and a lower guide (10).
Since it hits the roller (9B) having a small surface friction by passing between the roller (B) and B), the roller (9B) is surely guided to the nip portion (13) of the conveying roller pair (9).

The reference numerals in parentheses refer to the drawings and do not limit the configuration in any way.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 shows the overall configuration of an image forming apparatus (printer) including a sheet material conveying apparatus according to Embodiment 1 of the present invention, and FIGS. 2 and 3 show the sheet material conveying apparatus.

Here, the same members as those of the above-mentioned conventional example are designated by the same reference numerals, and the description of those which are functionally and structurally the same will be omitted.

In the present sheet material conveying device, the conveying guide 10 includes an upper guide 10A and a central guide 30.
And the lower guide 10B.

Downstream ends 31 and 32 of the upper guide 10A and the lower guide 10B are located at the nip portion 13 of the conveying roller pair 9.
It is located far away from.

Further, the downstream end 33 of the central guide 30 is
It is arranged so as to be located closer to the lower roller 9B having a smaller surface friction than the nip center line X (see FIG. 2) of the transport roller pair 9.

Although the central guide 30 and the downstream ends 33 and 32 of the lower guide 10B are in close proximity to each other, a gap is provided between them for the sheet material S1 to pass through.

FIG. 2 shows a case where the sheet material S1 is fed from the upstream sheet feeding cassette 1. Paper cassette 1
The leading end of the sheet material S1 fed from the lower guide 10B
Along the lower roller 9B and is guided to the nip portion 13 along the lower roller 9B. At this time, since the upper roller 9A has a large surface friction, the upper roller 9A
It is difficult to guide the front end of the sheet material S1 to the nip portion 13 along the line A, but it is difficult to guide the front end of the sheet material to the nip portion 13 with the lower roller 9B having a small surface friction. Get burned.

FIG. 3 shows a case where the sheet material S2 is manually fed from the paper discharge tray 2 at the downstream portion. The sheet material S2 that is manually fed from the paper discharge tray 2 has a pair of conveyance rollers 9
After passing through, the sheet passes between the central guide 30 and the upper guide 10A, and is located between the sheet feeding roller 11 and the uppermost sheet in the sheet feeding cassette 1. At this time, since the downstream end 33 of the center guide 30 is lower than the nip center line X, the leading end of the sheet material S2 passes without being caught by the center guide 30. Further, the downstream end 31 of the upper guide 10A is provided at a position where the manually inserted sheet material S2 is not caught, and the paper feed roller 1
It is sufficient to guide the sheet material S2 between the paper feed roller 11 and the uppermost paper in the cassette 1 accurately in the vicinity of 1. <Second Embodiment> FIGS. 4 and 5 show a sheet material conveying apparatus according to a second embodiment of the present invention.

In this case, the same members as those in the first embodiment are designated by the same reference numerals, and the description of those which are functionally and structurally the same will be omitted.

In the present sheet material conveying device, the central guide 35
An elastic sheet 36 is adhered to. This elastic sheet 36
Is disposed at a position lower than the nip center line of the transport roller pair 9 and is in contact with the lower guide 10B (see FIG. 5).

FIG. 4 shows a case where the sheet material S1 is fed from the sheet feeding cassette 1 at the upstream portion. Paper cassette 1
The leading end of the sheet material S1 fed from the lower guide 10B
Along with the central guide 35, the elastic sheet 3
6 and the lower guide 10B, and is guided to the nip portion 13 along the lower roller 9B.

When the sheet material S1 is fed, the elastic sheet 36 is deformed by the sheet material S1 and the central guide 3
A gap is formed between the sheet 5 and the lower guide 10B through which the sheet material S1 can pass, and the tip of the sheet material S1 is guided to the nip portion 13.

FIG. 5 shows a case where the sheet material S2 is manually fed from the sheet discharge tray 2 at the downstream side. The sheet material S2 that is manually fed from the paper discharge tray 2 has a pair of conveyance rollers 9
After passing through, the sheet passes between the central guide 35 and the upper guide 10A, and is located between the paper feed roller 11 and the uppermost paper in the paper feed cassette 1. At this time, since the tip of the elastic sheet 36 which is the downstream end of the central guide 35 is in contact with the lower guide 10B, the downstream end of the central guide 35 is closer to the nip center line than in the case of the first embodiment. Come to a low position. Therefore, even if the front end of the manually fed sheet material S2 is greatly curled downward, no catching occurs, and the sheet material S2 can be reliably guided between the sheet feeding roller 11 and the uppermost sheet of the cassette 1. .. <Third Embodiment> FIGS. 5 and 7 show a sheet material conveying device according to a third embodiment of the present invention.

Here, the same members as those in the first embodiment are designated by the same reference numerals, and the description of those that are functionally and structurally the same will be omitted.

The central guide 37 of the sheet material conveying apparatus is swingably attached to the image forming apparatus main body by a pin on the sort side of the sheet material passage area. Normally, the center guide 37 is in a state where the downstream end 40 is in contact with the lower guide 10B at a position lower than the nip center line due to its own weight.

FIG. 6 shows a case where the sheet material S1 is fed from the sheet feeding cassette 1 at the upstream portion. Paper cassette 1
The leading end of the sheet material S1 fed from the lower guide 10B
Along with the central guide 37, the central guide 3
The downstream end 40 of 7 is lifted around the pin 39 to form a gap through which the sheet material S1 passes and is guided to the nip portion 13.

FIG. 7 shows a case where the sheet material S2 is manually fed from the sheet discharge tray 2 at the downstream side. The sheet material S2 that is manually fed from the paper discharge tray 2 has a pair of conveyance rollers 9
After passing through, the sheet passes between the central guide 37 and the upper guide 10A, and is located between the sheet feeding roller 11 and the uppermost sheet in the sheet feeding cassette 1. At this time, the center guide 37 is in contact with the lower guide 10B around the pin 39, so that the same effect as in the case of the second embodiment can be obtained.

In this embodiment, the center guide 37 contacts the lower guide 10B by its own weight, but it may be contacted with the lower guide 10B by applying a load using a spring or the like.

A roller having a small surface friction (lower roller 9
As B), it is general to use a metal roller or a resin roller. However, in order to increase the carrying force, the sheet material S1 may be sandblasted on its surface or a roller with aluminum particles adhered to the sheet material S1. If the leading edge of the sheet material is not caught on the roller surface when the sheet is guided to 13, the surface treatment method and material may be selected.

[0047]

As described above, the sheet material conveying device of the image forming apparatus of the present invention can surely guide the leading end of the sheet material fed from the upstream portion to the nip portion of the conveying roller pair. Moreover, there is no problem in the conveyance of the sheet material fed from the downstream portion and passing through the pair of conveyance rollers.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of an image forming apparatus (printer) including a sheet conveying apparatus according to a first exemplary embodiment of the present invention.

FIG. 2 is a vertical sectional side view of the sheet material conveying device.

FIG. 3 is a vertical cross-sectional side view of the sheet material conveying device.

FIG. 4 is a vertical sectional side view of a sheet material conveying device according to a second embodiment of the present invention.

FIG. 5 is a vertical sectional side view of a sheet material conveying device according to a second embodiment of the present invention.

FIG. 6 is a vertical sectional side view of a sheet material conveying device according to a third embodiment of the present invention.

FIG. 7 is a vertical sectional side view of a sheet material conveying device according to a third embodiment of the present invention.

FIG. 8 is a vertical sectional side view of a conventional image forming apparatus (printer).

FIG. 9 is a vertical sectional side view of a conventional image forming apparatus (printer).

FIG. 10 is a vertical sectional side view of a conventional image forming apparatus (printer).

[Explanation of symbols]

 9 Conveying roller pair 9A Upper roller 9B Lower roller 10 Conveying guide 10A Upper guide 10B Lower guide 13 Nip portion 30, 35, 37 Central guide 33 Downstream end S1 Sheet material S2 fed from upstream portion S2 Feeding from downstream portion Sheet material X Nip centerline

Claims (1)

[Claims] 1. A pair of conveying rollers for selectively performing an operation of conveying a sheet material fed from an upstream portion to a downstream side and an operation of conveying a sheet material fed from a downstream portion to an upstream side, In a sheet material conveying device of an image forming apparatus, which comprises a conveying guide for guiding the leading end of the sheet material fed from the upstream portion to the nip portion of the conveying roller pair, the conveying roller pair has a large surface friction. The conveyance guide is composed of a roller and a roller having small surface friction, and the conveyance guide is constituted by three guides of an upper side, a center, and a lower side, and a downstream end of the center guide is located closer than the nip center line of the conveyance roller pair. A sheet material conveying device of an image forming apparatus, wherein the sheet material conveying device is located on the roller side having a small surface friction.