JPH04317944A - Transport device - Google Patents

Abstract

PURPOSE:To provide a sheet transport device, which can enable stable sheet registration of thin and thick papers and which can be operated without paying a high cost and using a high power as in the arrangement of prior art resulted from additional equiping of a brake. CONSTITUTION:A sheet transport device has a relay roller to send sheets to registration rollers 2, 3, wherein the transporting force of the relay roller shall be smaller than the buckling force of thick paper and greater than the buckling force of ordinary thin paper. On the other hand, the transporting force of intermediate rollers 5, 6 is made smaller than the buckling force of thick paper. When the leading edge of a thick sheet runs against the registration rollers 2, 3, the intermediate rollers 5, 6 should make slippage, while a deflection is formed in the case of a thin sheet.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a conveying device, and in particular,
The present invention relates to a conveyance device having a registration device such as a copying machine.

0002

2. Description of the Related Art Copying machines and the like use conveying devices having a registration device. In this registration device, in order to synchronize the optical system and the transfer paper, the leading edge of the transfer paper is brought into contact with the registration roller part to form a certain degree of flexure.
After that, the registration rollers are rotated. Furthermore, the resist device shown in Japanese Utility Model Publication No. 1-44516 is
In order to always have a certain amount of slack in the paper on the upstream side of the registration rollers 3, the conveyance speed between the sensors is calculated and corrected. Further, the registration device disclosed in Japanese Patent Application Laid-Open No. 62-49367 is provided with an auxiliary means for applying forward force to the paper and a slip roller on the paper introduction side of the registration roller.

0003

Nowadays, copying machines are required to be able to use a wide range of transfer paper types, from thin paper to thick paper. For example, it is required to be able to use everything from plain paper to cover sheets for bookbinding. However, in the prior art, registration misalignment of the cover sheet has become a problem. In other words, cardboard (
135 kg or 180 kg paper) has a strong stiffness even if an attempt is made to bend the paper, so a large force is required to convey the paper to the registration roller section. However, when the conveying force of the feed roller is greater than the braking force of the registration roller, the transfer paper cannot be stopped at the registration roller, and the leading edge of the paper advances beyond the nip of the registration roller, resulting in registration misalignment. occurs. In order to prevent this registration shift, some devices apply a brake to the registration roller portion to increase the braking force. However,
Increasing the load in this way increases the power of the motor and increases power consumption, making it difficult to save power in the machine. Particularly in recent years, there has been a demand for power-saving machines even for large machines. In addition, thin paper does not bend even if it is bent considerably, but thick paper is easily bent, and this bending causes white spots and the like to occur at the transfer area, resulting in poor transfer. Further, in the prior art, complicated control is required in which the paper is detected at two locations and the conveyance speed is determined and calculated in order to keep the amount of deflection of the registration portion constant, and the above-mentioned problem with thick paper occurs. Further, in the conventional technique, if the conveying force is set to suit thin paper, the conveying force for thick paper is insufficient, and the thick paper is not fed. On the other hand, if the conveyance force of the slip roller is set to ensure the conveyance force for thick paper, thin paper will be forcibly conveyed and a paper jam will occur on the bellows between the registration roller section and the slip roller section. Therefore,
Conveyance is unstable as it requires auxiliary means to provide forward force.

[0004] The present invention has been made in view of the problems of the prior art described above, and has been made to solve the problems.The purpose of the present invention is to enable stable registration of paper from thin paper to thick paper, and to eliminate the need for adding a brake as in the prior art. The object of the present invention is to provide a conveyance device that does not require high cost or high power consumption.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention abuts the leading edge of the transfer paper against the registration roller portion in order to synchronize with the transfer paper formed on the image forming apparatus. In a conveyance device having a registration device that causes a certain degree of deflection and then rotates the registration rollers, the conveyance device has a relay roller that feeds out to the registration roller section, and the conveyance force of the relay roller is smaller than the buckling force of the cardboard, In addition, the buckling force is greater than that of thin paper or plain paper.

[0006]

[Operation] By using the above means, the conveying force of the intermediate rollers 5 and 6 is made weaker than the buckling force of the cardboard, so that in the case of cardboard, the intermediate rollers 5 and 6 slip when the leading edge of the paper hits the registration rollers 2 and 3. In the case of thin paper, it is made to bend.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is an explanatory diagram of a copying machine to which a conveyance device according to the present invention is applied, and FIGS. 2 and 3 are explanatory diagrams showing the operating state of the conveyance device. In these figures, 1 is a photoreceptor, 2 and 3 are registration rollers, 4 is a transfer paper, 5 and 6 are intermediate rollers, and 7
is a spring, and 8 is a bearing. Resist rollers 2, 3
The transfer paper 4 is fed to the photoreceptor 1 in synchronization with the image formed on the surface of the photoreceptor 1. This control is a known technique and will not be described further. The paper is sent to the registration rollers 2 and 3 by intermediate rollers 5 and 6, and when the leading edge of the paper reaches the registration portion, the registration rollers 2 and 3 are stopped. In order to prevent the leading edge of the paper from shifting, the intermediate rollers 5 and 6 are rotated so that the paper is sufficiently bent. Thereafter, the registration rollers 2 and 3 rotate in synchronization with the photoreceptor 1 and feed the paper to the photoreceptor 1. In this way, it is common to bend the paper to prevent the registration from shifting. However, when trying to create a deflection by feeding a cover sheet or the like, the above-mentioned problems occur. This problem is related to the force that causes the paper to stop (braking force) and the force that causes the paper to bend (buckling force of the paper) when the registration rollers 2 and 3 stop. When the buckling force becomes larger than the braking force, the leading edge of the paper protrudes from the registration rollers 2 and 3, resulting in poor registration. On the other hand, if an attempt is made to increase this braking force, the mechanical load will increase. The present invention uses the intermediate rollers 5 and 6 due to the buckling force of the cardboard.
In the case of thick paper, the intermediate rollers 5 and 6 slip when the leading edge of the paper hits the registration rollers 2 and 3, and in the case of thin paper, the paper is bent. The braking force R of registration rollers 2 and 3 is 500g.
There are about f. This braking force R is 500gf, which means
The load torque is 500gf. As for the configuration of the registration rollers 2 and 3, a rubber roller is used for the driving side registration roller 2, a roller or roller made of polyacetal, aluminum, or stainless steel is used for the driven side registration roller 3, and the driven side registration roller 3 is supported by a spring 7. 8 to the drive-side registration roller 2 (see Figure 1).
. The buckling force of the transfer paper 4 is from several grams to several tens of grams for thin paper and plain paper (up to about 55 kg), and for medium thickness paper (70 to 90 kg).
0kg) About 50-60g for paper, 135-1 for thick paper
At 80 kg, it weighs from several hundred grams to over 500 grams. Therefore, even if an attempt is made to bend the cardboard, the buckling force may be greater than the resist braking force. Relay rollers 5, 6
In order to make the conveying force F smaller than the buckling force of the cardboard, (1) the pressing force of the relay rollers 5, 6 may be made small, (2) the driving side rollers 5 of the relay rollers 5, 6 may be replaced with metal rollers ( It may be made of stainless steel, aluminum) or resin (polyacetal, etc.) to have a lower coefficient of friction than ordinary rubber rollers and reduce the conveying force.

In the above-described embodiment configured in this way, even if the braking force of the registration rollers 2 and 3 is relatively weak (
The load on the registration rollers is light), and the conveying force of the intermediate rollers 5 and 6 is smaller than the buckling force of thick paper and larger than the buckling force of thin paper, enabling accurate registration with low torque (saving power). becomes. Also, for thick paper, use registration roller 2.
, Because it does not forcibly form a deflection by hitting the third part,
Image defects such as transfer white spots due to bending do not occur. Furthermore, there is a conveyance force that can create sufficient flexure for plain paper or thin paper, so that registration misalignment does not occur even with thin paper.

[0009]

[Effects of the Invention] As explained above, according to the present invention,
Even if the braking force of the registration rollers is relatively weak (the load on the registration rollers is light), low torque (savings) can be achieved by making the conveying force of the intermediate rollers smaller than the buckling force of thick paper and larger than the buckling force of thin paper. Accurate resist alignment is possible using electric power). Further, since the cardboard is not forced to bend by abutting against the registration roller portion, image defects such as transfer white spots due to bending do not occur. Furthermore, there is a conveyance force that can create sufficient flexure for plain paper or thin paper, so that registration misalignment does not occur even with thin paper.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a copying machine to which a conveying device according to the present invention is applied.

FIG. 2 is an explanatory diagram showing the operating state of the transport device.

FIG. 3 is an explanatory diagram showing the operating state of the transport device.

[Explanation of symbols]

1 Photoreceptor 2, 3 Registration roller 4 Transfer paper 5, 6 Intermediate roller 7 Spring 8 Bearing

Claims (5)

[Claims] Claim 1: In order to synchronize the image formed on the image forming device with the transfer paper, the leading edge of the transfer paper is brought into contact with the registration roller section to create a certain amount of deflection, and then the registration roller is rotated. A conveyance device having a registration device configured to have a conveyance device that has a relay roller that sends out to the registration roller section, and has a conveyance force of the relay roller that is smaller than the buckling force of the cardboard buckling roller, and that can be used for thin paper or plain paper. A conveying device characterized by having a buckling force greater than that of. 2. The conveying device according to claim 1, wherein the pressing force of the relay roller is reduced in order to make the conveying force smaller than the buckling force of the cardboard. 3. The conveying device according to claim 1, wherein the friction coefficient of the drive-side roller of the relay roller is set to be small to reduce the conveying force. 4. The conveying device according to claim 1, wherein the driving side roller of the relay roller is a metal roller to reduce the conveying force. 5. The conveyance device according to claim 1, wherein the drive side roller of the relay roller is made of a polyacetal material to reduce conveyance force.