JPH04189237A - Paper feeding device - Google Patents

Abstract

PURPOSE:To prevent the generation of a deflection and a reduction in sheet carrying performance in its turn by making a curved protruding part separately from a lower paper guide member body, and integrally fixing it to the lower paper guide member body. CONSTITUTION:A curved protruding part 6 provided on a lower paper guide member 3 between a pair of carrying rollers 1 and a pair of resist rollers 2 is made separately from a lower paper guide member body 7, and integrally fixed to the lower paper guide member body 7. Thus, the curved protruding part 6 and the lower paper guide member body 7 can be formed by suitable materials and working methods, respectively, and a deflection as in the integral formation is never caused.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a paper feeding device of an image forming apparatus, and in particular to a paper guide between a pair of registration rollers and a pair of conveyance rollers upstream of the pair of registration rollers for timing the feeding of paper. Regarding parts.

Means for feeding recording paper sent out from a paper feeding device of an image forming apparatus such as an electrophotographic copying machine or a printer so that its leading edge aligns with the leading edge of an image forming section on a photoreceptor at a transfer section. For example, a pair of registration rollers provided on the paper conveyance path is used.

FIG. 5 is a diagram illustrating the configuration of an example of a paper feeding device provided with a pair of registration rollers, in which a pair of registration rollers 2 is provided on the downstream side of the conveyance roller 1 that conveys the paper P sent out from the paper feeding section one by one. are provided, and a paper sensor 4 is provided immediately in front of the pair of registration rollers 2. When the sensor 4 detects the leading edge of the paper sent out by the pair of transport rollers 1, the pair of registration rollers stops, and after the leading edge of the paper hits the nip of the pair of registration rollers that are stopped, the pair of transport rollers 1 After the paper is over-fed by a predetermined amount, the paper stops, and as shown by the two-dot chain line in FIG.
An upwardly curved buckling is formed between the rollers 2 and 2, and waits with its tip pressed against the nip portion of the registration roller 2. When the pair of registration rollers 2 starts rotating at the timing when the leading edge of the paper is aligned with the leading edge of the image forming section on the photoreceptor, the paper P is exposed to light by the pair of registration rollers 2 and the pair of transport rollers 1, as shown in FIG. The image is transported to a transfer section along the body. Note that the transport roller pair 1 transports the paper at a slightly higher speed and with a stronger transport force than the registration roller pair, so that stable transport is performed.

As described above, the leading edge of the paper transported by the transport roller pair 1 is guided to the nip part of the registration roller pair 2, and the paper whose leading edge collides with the nip part of the registration roller pair 2 is prevented from buckling upward. In order to allow the paper guide member between the conveyance roller pair 1 and the registration roller pair 2 to The lower guide member 3 forms a large inclined surface on the first side.

However, in a paper feeding device with such a configuration, when transporting thick paper such as a postcard as recording paper, if the recording paper whose leading edge is in contact with the registration roller is fed too much, the stiffness of the paper will cause the paper to reach the sixth position. As shown in the figure, there is a case where the roller does not buckle and, due to the thrust of the pair of conveying rollers, enters the nip portion of the pair of registration rollers that are in pressure contact with each other and penetrates to the downstream side. As a result, correct tip alignment cannot be obtained.

In order to solve this problem,
In the publication, as shown in FIG. 8, a lower paper guide member 3 between a pair of conveyance rollers 1 and a pair of registration rollers 2 has an upwardly curved protrusion 5, which allows the sheet to be deflected upward. A paper feeding device has been proposed in which an upper paper guide member 9 is provided to guide the paper to the nip portion of a pair of registration rollers. After the paper is deflected upward by the curved protrusion 5, it is bent downward by the upper paper guide member, thereby folding the paper strainer and weakening the thrust against the nip.

The above problems will be resolved. It is easy to manufacture a guide member with such a curved protrusion by integrally molding it from synthetic resin, but in that case, due to thermal expansion, it may warp as shown in Figure 9, which may cause jams. Become. In addition, if it is made from sheet metal, it is necessary to insert a diaphragm in order to create the curved portion 5, and for this reason, it is necessary to insert a diaphragm that spans all pairs of paper conveyance paths.

As shown in Figure 10, undulation occurs on the flat surfaces at both ends in the conveyance direction, reducing the flatness, and tension due to the aperture reduces the straightness of both ends, which adversely affects conveyance performance (
This may cause paper wrinkles, etc.). Therefore,
If the curved protrusion 5' is locally created by squeezing as shown in Fig. 11, it will be easier to ensure the flatness of the part other than the protrusion 5', but the paper passing through this part will be wrinkled. There is a possibility that this may occur.

Problem to be Solved by the Invention ■ The present invention focuses on the effects of a paper feeding device having an upwardly curved protrusion on the lower paper guide member, and overcomes the above-mentioned difficulties in producing a protrusion with this shape. did. It is an object of the present invention to provide a paper feeding device in which there is no possibility that distortion occurs in a lower paper guide member and thereby hinders paper conveyance performance.

In order to solve the above-mentioned problem, the paper feeding device of the present invention for carrying out the above-mentioned tasks has a curved protrusion provided on the lower paper guide member between the transport roller pair and the registration roller pair. It is characterized in that it is made separately from the main body and is integrally fixed to the lower paper guide member main body.

As mentioned above, since the curved protrusion and the lower paper guide member main body are made separately and joined together, they can be made using materials and processing methods suitable for each, and when made as one body. No distortion occurs. The curved protrusion can be easily made by molding synthetic resin, and the guide member main body can be made from a metal plate, which is suitable in terms of processing and strength. The method for positioning and fixing the curved protrusion to the guide member body is to provide a recess with a step in the guide member body, fit the protrusion provided on the curved protrusion corresponding to the recess, and process the concave part to prevent it from being pulled out. It is easy and reliable to install.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to a paper feeding device having the configuration shown in FIG. 8. Therefore, members having the same functions will be described with the same reference numerals.

In this embodiment, the lower paper guide member having an upwardly projecting curved protrusion is made separately into a curved protrusion member 6 and a paper guide member 7, which are joined together.

As shown in FIG. 2, the curved protruding member 6 has a width that is equal to or greater than the total width of the largest size paper P to be conveyed, and is made of synthetic resin by molding into a substantially semi-cylindrical shape. Third
As shown in the figure, a plurality of grooves 6a extending in the conveyance direction may be provided on the curved surface. On the other hand, the upper surface of the paper guide member main body 7
As shown in the figure, the pair of transport rollers 1 and the pair of registration rollers 2 are installed so as to extend slightly downward and parallel to the straight line connecting their nips, and the curved protruding member 6 is attached to guide the lower paper so as to protrude upward from the two straight lines. It is attached to the member body 7.

The lower paper guide member main body 7 is made of a metal plate, and has a curved protrusion 6.
A recessed groove 7a with a step into which the lower part fits at a certain depth is formed by press working over the entire width, and a plurality of mounting holes 7b are bored at the bottom of the groove. When attaching the resin curved protruding member 6 to the lower paper guide member main body 7, as shown in FIG. A protrusion 8 integrally protruded from the lower surface of the mold is fixed by heat caulking or screwed.

Since the curved protrusion member 6 is installed by falling into a groove with a step from the upper surface of the lower paper guide member, paper gets stuck in the interface between the upper surface of the lower paper guide member and the curved protrusion member, causing a jam. This will be prevented.

By making the main body of the lower paper guide member and the curved protruding member separately and joining them together, they can be made using materials and processing methods that are suitable for each, thereby preventing the occurrence of distortion and the deterioration of paper conveyance performance. It can be prevented. By making the curved protruding member by resin molding, it is not limited by the drawing depth as is the case when it is made by deep drawing of metal, so it can be freely molded into the shape that is most suitable for the conveyance performance for forming the pack ring. Is possible. Further, since the lower paper guide member main body has a simple shape, it is suitable for making from a metal plate, and it is easy to ensure flatness, straightness of the tip, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a paper feeding device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the outer shape of the curved protrusion, FIG. 3 is a perspective view showing a modification thereof, and FIG. 4 5 is a perspective view showing a state in which the curved protrusion is attached to the lower paper guide member main body, FIG. 5 is a sectional view showing an example of the configuration of a conventional general paper feeding device, and FIGS. 6 and 7 are its sectional views. An explanatory diagram for explaining the operation, FIG. 8 is a sectional view showing an example of the structure of a paper feeding device proposed to solve the problems of conventional devices, and FIGS. 9, 10, 5, and 11 show the problems. FIG. 1... Conveyance roller pair 2... Registration roller pair 3... Lower paper guide member 4...
...Sensor 6...Curved protruding member 7...Lower paper guide member main body 9...Upper paper guide member-> Agent Patent attorney Takehisa Ito 2-゛ [No. 1 Figure 7b Figure 2 Figure 3a Figure 40 Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] (1) The lower paper guide member between the pair of registration rollers and the pair of paper transport rollers provided on the upstream side thereof has an upwardly curved protrusion, and the upper paper guide member is moved upwardly by the curved protrusion. In a paper feeding device of an image forming apparatus that is provided to guide paper deflected by a pair of registration rollers to a nip portion of a pair of registration rollers, the curved protrusion is made separately from the lower paper guide member main body, and the lower paper guide A paper feeding device characterized in that it is integrally fixed to a member main body. (2) The paper feeding device according to claim 1, wherein the curved protrusion is molded from synthetic resin, and the lower paper guide member main body is made from a metal plate. (3) The lower paper guide member main body is provided with a stepped recess, and the curved protrusion is provided with a corresponding protrusion, and the protrusion is fitted into the recess to form the curved protrusion. The paper feeding device according to claim 2, wherein the paper feeding device is fixed to the lower paper guide member main body.