JP2000136050A - Paper sheet carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the change of the route of a paper sheet carrying path during the press-contact/separation of a roller and carry the paper sheet accurately by press-contacting/separating the roller arranged on the upper side substantially in a gravity direction out of the carrying roller for the roller arranged on the lower side. SOLUTION: A paper sheet guide plate 8 in whose inside a heater 9 is arranged is fixed on the base 11 and energized in an arrow mark direction by a spring 14 and a pressurized roller 2 is installed on the tip of the arm 12 whose rotation is restrained by a pin 13. A heat roller 1 in whose inside the heater 3 such as a halogen lamp is provided is installed in the arm 5 installed on the fulcrum A rotatably and always energized in the arrow mark direction by a spring 7 and the arm 5 is moved in the arrow mark direction around the fulcrum A by the movement of the cam surface of a cam 6 and the heat roller 1 of the upper side is press-contacted/separated for the pressurized roller 2 of the lower side. Thus, the carrying path route of the paper sheet 10 is stabilized during the action of the carrying rollers 1, 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper transport apparatus provided with at least one pair of transport rollers capable of freely pressing and separating on a paper transport path.

[0002]

2. Description of the Related Art There is known a paper transport apparatus having at least one pair of transport rollers which can be freely pressed and separated on a paper transport path. This type of paper transport device is
For example, as shown in JP-B-64-5302, the present invention is applied to a fixing device of a laser printer that performs printing on continuous paper. In a laser printer that prints on continuous paper, if the paper is held between a heat roller and a pressure roller, which form a pair of transport rollers, the toner image on the paper will be offset to the surface of the heat roller. Or, because it is possible to cause a problem in print quality such that the toner image of the pinched portion is excessively melted and melted by excessive heating, it is possible to cause a problem in print quality.In general, when printing is stopped, the pressure roller is separated from the heat roller when printing is stopped, It is configured to solve the problem caused by the overheating.

[0003]

By the way, in a conventional paper conveying apparatus, a pair of conveying rollers (fixing rollers) is used.
Among them, the roller (pressing roller) disposed substantially below in the direction of gravity is provided so as to be able to press / separate from the roller (heat roller) disposed above, so that the lower roller moves. Then, the paper supported in contact with the lower roller surface also comes into pressure contact with or separates from the upper roller.

As described above, in the prior art, since the path itself of the sheet transport path is also moved during the pressing / separating operation of the transport roller, the pressure roller is pressed against the heat roller when the next printing is resumed. When the paper transport path is not restored to the original state, the fixing strength is not stable, or when the pressure roller is separated, paper slack occurs at the stage before the pressure contact part between the heat roller and the pressure roller. During standby, the paper comes into contact with the heat roller, causing a problem that the toner image on the paper is offset on the surface of the heat roller.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus capable of accurately conveying sheets without moving the path of a sheet conveying path due to the pressing / separating operation of the conveying rollers. is there.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paper transport apparatus having at least one pair of transport rollers capable of being pressed and separated on a paper transport path. This is achieved by having means for pressing / separating the roller disposed on the upper side with respect to the roller disposed on the lower side.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which one embodiment of the present invention is applied to a fixing device of a laser printer will be described below with reference to FIG.

In FIG. 1, a paper guide plate 8 is a base 11
, And the base 11 is fixed to a housing (not shown) of the main body. The paper guide plate 8 may be provided with a heater 9 therein as required. When the heater 9 is provided, the temperature guide (not shown) is used to control the paper guide plate 8.
Is controlled.

The pressure roller 2 has an elastic layer made of silicon rubber or the like on its surface, and is provided at the tip of the arm 12.
The arm 12 is pulled in the direction of the arrow by a spring 14, and its rotation is suppressed by a pin 13 attached to the base 11.

The heat roller 1 has on its surface a release layer made of a material having good release properties such as silicone rubber or fluororesin, and a heater 3 such as a halogen lamp serving as a heating means is provided inside.

The arm 5 is rotatably attached to a fulcrum A serving as a center of rotation, and is always pulled by a spring 7 in the direction of the arrow. The relationship between the load F generated by the spring 7 and the load F generated by the spring 14 always satisfies the relationship of F ′> F so as not to decrease the pressure of the nip generated by the spring 14 when the nip is formed. Is set to

The arm 5 can be moved in the direction of the arrow around the fulcrum A by moving the cam surface of a cam 6 driven by a drive source (not shown) such as a motor. 2 can be pressed / separated.

With the above configuration, the toner image formed on the paper 10 by electrostatic transfer is preheated by passing on the paper guide plate 8, passes between the heat rollers 1 pressed against the pressure roller 2, and is pinched. The paper 1 is heated and pressurized by being conveyed.
0 is fixed.

[0014]

According to the present invention, there is provided a sheet conveying apparatus capable of accurately conveying sheets without moving the path of the sheet conveying path due to the pressing / separating operation of the conveying rollers. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

[Description of Signs] 1 ... Heat roller, 2 ... Pressure roller, 5 ... Arm, 10 ... Paper.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaru Sawahata 1060 Takeda, Hitachinaka-shi, Ibaraki F-term in Hitachi Koki Co., Ltd. (reference) 2H072 CA01 CA02 CB08 HA04 JA02 JC02 3F049 DA12 LA07 LB01

Claims (2)

[Claims] 1. A paper transport device comprising at least one pair of transport rollers capable of being pressed and separated on a paper transport path, wherein, of the transport rollers, a roller disposed substantially above in the direction of gravity is provided. A sheet transport device comprising means for pressing / separating a roller disposed on a lower side. 2. The sheet conveying device according to claim 1, wherein the roller disposed on the upper side is a heat roller provided with a heating unit.