JPH02243438A - Paper conveyor - Google Patents

Abstract

PURPOSE:To lead a sheet to a pressing part of a roller pair smoothly all the time as well as to prevent a paper jam from occurring by installing a part, doubling as a sheet conveying guide, of an elastic support member in a position guiding the sheet to the pressing part of the paired roller free movements. CONSTITUTION:When a position of a nip (pressing part) 11 of a roller pair goes up, a driven roller 4 goes up as well. Consequently, a doglegged arm 6'-3 of an elastic support member 6' pivotally supporting this shaft 4-1 at the tip is also displaced upward, and a position of a bending part 6'-5 doubling as the sheet conveying guide also goes up. Accordingly, a sheet 10 being guide by this bending part 6'-5 is smoothly guided into this nip 11 without colliding with each belly of rollers 4, 5, so that transfer deflection and any paper jam will not occur there.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a paper conveyance device having a pair of paper conveyance rollers whose pressure contact portions can be opened and closed.

In printers, copying machines, etc., the main body of the device is divided into two units, an upper and lower unit, which are pivoted to each other at the back or on one side, in order to facilitate removal of paper jams, inspection and replacement of parts, etc. Recently, many so-called clamshell-type machines have been released with a wide open mouth. In these devices, in order to easily remove paper jams, when the upper and lower units are opened, the upper roller and lower roller of the paper transport roller are released at their pressure contact portions for the upper and lower units, respectively. There is something.

Figures 5 to 7 show a schematic configuration of an example of this type of laser printer.The main body of the device consists of an upper unit 1 and a lower unit 2, which are pivotally connected to each other at the back side when viewed from the operator. There is. The upper unit 1 includes a laser writing optical system and the like, and the lower unit 2 includes a paper feeding section, an image forming section 20, a fixing device 3, and the like. The paper fixed by the fixing device 3 is transferred to the top of the upper unit 1 by a transport roller pair consisting of an upper roller 5 that is rotationally driven in the paper ejection direction and a driven roller 4 that is in pressure contact with the upper roller 4 across the paper transport path. The paper is ejected to a paper ejection path leading to a paper ejection tray provided on the surface or outside the machine. When the upper unit 1 is lifted, the upper roller 5 of this pair of conveyance rollers is lifted together with the upper roller 5, and is separated from the driven roller 4 attached to the lower unit 2 by a large distance.

In paper conveyance rollers with such a configuration, the mutual positions of the upper and lower rollers may vary due to the stacking up of component precision.
If the shaft is made of plastic to reduce costs and eliminate the need for static grounding, deflection and eccentricity will increase, and variations in the position of the nip (pressure contact) will become noticeable.

As shown in FIGS. 8 and 9, the driven roller 4 is supported by an elastic support member 6 made of a leaf spring so that the pressure contact force between both rollers remains at the required value even if the nip position varies. hand,
Guide 7 is supported.

As shown in FIG. 9, the elastic support member 6 is attached to the guide 7 by pressing into the engagement portion 7-1, which has a cross-shaped slit in the bottle 7-1, and engaging the guide 7. The two guide bins 7-2 installed in the support member 6-2 are
The shaft end 4-1 of the driven roller 4 is rotated to a shaft support 6-4 formed by rounding the tips of two arms 6-3 protruding from the upper part of the support member 6. It is supported in a flexible manner.

As shown in FIGS. 8 and 9, the arm of the conventional elastic support member has its base extending in a straight line from the root, so that the height of the arm is equal to the conveyance guide 7 that guides the paper to the nip of the pair of rollers. The height is slightly lower than the height of the tip 7-3.

FIG. 10 shows a state where the position of the nip portion 11 of the rollers 4 and 5 is within an appropriate range with respect to the tip 7-3 of the conveyance guide 7, and the paper 10 is guided to the upper surface of the conveyance guide 7. It is fed into the nip 11 via the tip 7-3. However, as shown in FIG. 11, if the position of the leek 111 is above the appropriate height range with respect to the conveyance guide 7, the leading edge of the sheet guided and conveyed by the conveyance guide 7 will be moved by the driven roller. 4 and cannot be smoothly fed into the nip 11 of the pair of rollers, and the impact causes blurring of the transferred image at the transfer section, as shown in FIG. 11.
The paper will jam.

However, the present invention provides a pair of rollers that solves the above-mentioned problems of the conventional configuration of a paper conveyance device having a pair of rollers in which the pressure contact portion of the pair of rollers is releasable and the driven roller is supported by an elastic support member. It is an object of the present invention to provide a paper conveyance device that can smoothly insert paper into a pressure contact part even when the height of the pressure contact part changes.

In order to solve the above problem, the paper conveying device of the present invention for It is characterized in that a portion of the member that also serves as a paper conveyance guide moves to a position where the paper is guided to the pressure contact portion of the pair of rollers.

7-1 With this configuration, when the position of the pressure contact portion of the roller pair changes, the position of the driven roller changes accordingly, and the roller also serves as a paper conveyance guide formed on the elastic support member of the driven roller. Since the portion moves to a position that guides the paper to the pressure contact portion, the paper is always smoothly inserted into the pressure contact portion.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIGS. 1 and 2 are diagrams showing an embodiment in which the present invention is applied to the paper conveying device described in FIGS. 8 and 9. Therefore, members having the same functions are given the same reference numerals, and the explanation will focus on the differences.

In this embodiment, the arm 6'-3 of the elastic support member 6' of the driven roller 4 is bent so as to protrude upward in the shape of a "<", and its bent portion 6'5 also serves as a paper conveyance guide. ing. The height of the tip @7-3 of the conveyance guide member 7 is set to a height that does not obstruct the sheet inserted into the nip even if the nip position is considerably lowered. The other configurations are similar to the examples shown in FIGS. 8 and 9.

FIG. 3 shows the paper transport state when the nip position is quite high. When the nip position 11 rises, the driven roller 4 rises, and as a result, the arm 6'-3 of the elastic support member that pivotally supports the shaft 4-1 at its tip is also displaced upward, and the arm 6'-3, which also serves as a paper conveyance guide, is bent upward. The position of the section 6'-5 also rises, and the sheet 10 guided thereby is guided into the nip 11.

FIG. 4 shows a state in which the position of the nip 11 is lowered, and as the nip 11 lowers, the arm 6'-3 is bent downward, and the bent part 6'-5, which also serves as a paper conveyance guide, also bends accordingly. descend. Therefore, in this case as well, the sheet 10 is guided by the bend 6'-5 and led to the nip 11. At this time, the position of the tip 7-3 of the guide member 7 is considerably lowered, so that it does not interfere with the conveyance of the paper.

East-1 As described above, according to the present invention, even if the height of the nip portion of the pair of transport rollers changes, the paper can always be smoothly guided to the nip portion, and the sheet collides with the belly of the roller. Effective in preventing transfer blur and jams.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a perspective view showing an elastic support member of the driven roller, FIGS.
The figure is an explanatory diagram for explaining its operation, FIGS. 5 and 6 are explanatory diagrams conceptually showing an example of a laser printer with a structure in which the main body of the device opens up and down, and FIG. 8 is a perspective view showing a conventional conveying roller, FIG. 9 is a perspective view showing an elastic support member of the driven roller, and FIGS. 10 and 11 are explanations explaining its functions and drawbacks. It is a diagram. DESCRIPTION OF SYMBOLS 1...Upper unit, 2...Lower unit, 4...Followed roller, 5...Drive roller, 6.6'...Elastic support member, 6'-3...Arm, 6' -5... Portion that also serves as a paper conveyance guide, 7...
Guide member, 11...Tub on pressure contact part) Fig. 1 Fig. 2 Fig. Fig. Fig. Fig. Fig. Fig. 10 Fig. 11 Fig.

Claims (1)

[Claims] A pressure contact portion of a roller pair consisting of a drive roller that is rotationally driven in the paper transport direction and a driven roller that is pressed against the drive roller and driven by the drive roller across the paper transport path is releasable, and the driven roller is In a paper transport device having a pair of transport rollers supported by an elastic support member, a part of the elastic support member also serves as a paper transport guide, and the paper of the elastic support member is moved in accordance with the displacement of the driven roller. A paper conveyance device characterized in that a portion that also serves as a conveyance guide moves to a position where the sheet is guided to a pressure contact portion of a pair of rollers.