JP2624188B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a fixing device incorporated in an electrophotographic apparatus or the like for fixing a toner transferred onto paper by heat and pressure.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional example. In the conventional example shown in FIG. 3, a fixing roller 101 having a heater 102 therein is used.
Has a metal core 103 on the inside and a Teflon elastic layer 104 on the outside. Then, when the sheet P to which the toner T is transferred is sent, the toner information on the sheet P is fixed by heat and pressure on the sheet P. In this case, a follow-up roller (pressing roller) 105 that presses against the fixing roller 101 to perform a pressing operation has a metal core 106 and a silicon rubber elastic layer 107 covering the outer periphery thereof. Has become.

[0003] The toner fixing operation is started by turning on the power of the electrophotographic apparatus, turning on a heater lamp to increase the fixing surface temperature. Therefore, the electrophotographic apparatus cannot start printing until the surface temperature of the fixing roller rises to a state where fixing can be performed, that is, during the warm-up time, which is a waiting time for the user.

The warm-up time is a time required for the fixing roller 101 in the fixing device to rise to an appropriate temperature. Conventionally, the temperature rising characteristic of this fixing device is based on the heat capacity of the fixing roller 101 and the heat capacity of the internal heater 102. It depends on the heat radiation characteristics.

[0005]

In the above-described conventional heat roller fixing device, since the fixing roller 101, the follow-up roller 105, and the internal heater 102 are used, the warm-up time is equal to the heat capacity of the fixing roller and the heat of the heater. It is determined by the radiation characteristics, and it is necessary to apply a large amount of power to the heater for a long time at the time of starting. Therefore, there is a problem that the warm-up time is long and the power consumption is large.

In order to solve these problems, in a conventional electrophotographic apparatus, a technique of increasing the surface temperature of the fixing roller or rotating the fixing roller at a slow speed has been attempted in order to sufficiently fix the sheet with the fixing roller alone. Was.

On the other hand, recently, there is a strong demand for high speed electrophotographic devices on the consumer side, and therefore, shortening the warm-up time is one of the important issues (reducing this time). This leads to higher speed of the electrophotographic apparatus).

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device which can solve the disadvantages of the prior art, and in particular, can increase the surface temperature of the fixing roller quickly to the operating temperature.

[0009]

According to the present invention, there is provided a heat roller for fixing, a pressing roller which rotates in contact with the heat roller, and a supporting roller for the pressing roller and a fixing roller for the heat roller. A fixing device that includes a pressing unit that presses the heat roller with a predetermined pressing force and a heat roller driving unit that rotationally drives the heat roller, and pressurizes and heat-fixes the sheet with the transferred development toner. Is provided with pressure roller rotation drive means for rotating the pressure roller in the same rotation direction as the heat roller described above.

[0010] Further, the pressure means has an inter-axis distance adjusting function capable of arbitrarily setting the inter-axis distance between the heat roller and the pressure roller. This aims to achieve the above-mentioned object.

[0011]

[Operation] First, during the warm-up time of the entire apparatus, the heat roller 1 is rotated at a high speed by a heat roller driving means (not shown). At this time, the pressing means 3 is operated so that the nip width between the pressure roller 2 and the heat roller 1 is reduced. Further, the pressure roller 2 is rotated by the pressure roller rotation driving means 5 in the same direction as the heat roller 1 (the direction opposite to the normal rotation direction of the pressure roller 2). By this action,
Friction heat is generated on the contact surface between the fixing roller 1 and the pressure roller 2, and by heating the heater 1 </ b> A inside the heat roller 1, the heat roller 1 is synergized with the friction heat with the pressure roller 2. As a result, the temperature required for fixing can be increased almost instantaneously.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The prior art shown in FIGS. 1 and 2 is a fixing heat roller 1, a pressure roller 2 rotating in contact with the heat roller 1, and supporting and supporting the pressure roller 2. Pressing means 3 for pressing the pressure roller 2 toward the heat roller 1 with a predetermined pressing force;
And a heat roller driving means (not shown) for rotationally driving.

The pressure roller 2 is provided with pressure roller rotation driving means 5 for rotating the pressure roller 2 in the same rotational direction as the heat roller 1 described above. The pressure roller rotation drive means 5 includes a motor 5A, a driving gear 5a driven by the motor 5A, and a driven gear 5b meshed with the driving gear 5a and fixed to an end coaxially with the pressure roller 2. Have been.

Further, the heat roller driving means has a high-speed rotation control function for rotating the heat roller 1 at a high speed.

The pressing means 3 includes a lever mechanism 3A for pressing the pressure roller 2 toward the heat roller 1, and a lever mechanism 3A.
A, and a cam mechanism 3B for urging the operation of A
And a stepping motor 3C for controlling the operation of the motor. Thus, the pressing means 3 has an inter-axis distance adjusting function capable of arbitrarily setting the inter-axis distance between the heat roller 1 and the pressure roller 2 by variably controlling the rotation angle by the stepping motor 3C. It has become. Reference numeral 3E denotes a tension spring that acts in a direction to pull the entire pressure roller 2 away from the heat roller 1 described above.

The above-described heat roller 1 is provided with a heater 1A, and is constituted by a core 1B made of a metal having good heat conductivity and a heat-resistant elastic layer 1C such as Teflon which is coated around the core 1B. The heater 1A is housed in the core 1B.

A pressure roller (follow-up roller) 2 is a roller for assisting the heat roller 1 to press the toner T transferred onto the sheet P into pressure, and surrounds a core 2A made of metal such as iron. Is covered with a heat-resistant elastic layer 2B made of silicone rubber.

Next, the operation of the above embodiment will be described.

First, during the warm-up time of the fixing device,
The heat roller 1 is rotated at high speed by a heat roller driving means (not shown). At this time, the cam mechanism 3B is driven so that the nip width between the pressure roller 2 and the heat roller 1 is reduced, and the lever mechanism 3A is operated to move the pressure roller 2 in the direction of arrow A about the fulcrum 3a. Further, the pressure roller 2 is rotated in the same direction as the heat roller 1 by the pressure roller rotation driving means 5.

By this action, frictional heat is generated on the contact surface between the fixing roller 1 and the pressure roller 2, and the temperature of the heat roller 1 is increased by heating the heater 1A inside the heat roller 1. The temperature can be increased almost instantaneously in synergy with the heat of friction with the pressure roller 2.

As a result, the warm-up time can be reduced, and the amount of heat given by the frictional heat does not need to be given from the heater 1A. Significantly lower power consumption.

FIG. 2 is a side view showing the internal structure of the fixing device according to the present embodiment in a normal printing operation state. The lever mechanism 3A is lifted by the cam mechanism 3B against the above-described tension spring 3E, whereby the pressure roller 2 and the heat roller 1 form a certain nip width, and the toner T transferred onto the paper P is removed. Fixing can be performed by obtaining a pressure sufficient for fixing.

[0024]

According to the present invention, the heat roller and the pressure roller are rotated in the same direction during the warm-up time of the printer, and the pressure roller is heated. By generating frictional heat by pressing against the roller side, the temperature of the heat roller surface can be instantaneously set to the temperature required for fixing, and the warm-up time can be greatly reduced. Further, since the amount of electric power of the heater inside the fixing roller can be reduced and saved at the time of warm-up, it is possible to provide an unprecedented excellent fixing device that can reduce the power consumption of the electrophotographic apparatus.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram illustrating a state during a normal printing operation in the fixing device of FIG. 1;

FIG. 3 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat roller 2 Pressure roller 3 Pressing means 3A Lever mechanism 3B Cam mechanism 3C Stepping motor 5 Pressure roller rotation driving means

Claims (3)

(57) [Claims] 1. A heat roller for fixing, a pressure roller rotating in contact with the heat roller, and supporting the pressure roller and pressing the pressure roller toward the heat roller with a predetermined pressing force. A fixing device that includes a pressing unit that presses, and a heat roller driving unit that rotationally drives the heat roller, and pressurizes and heats the sheet to which the transferred development toner is attached; A pressure roller rotation drive unit that drives the roller to rotate in the same rotation direction as the heat roller described above is provided, and the pressing unit can arbitrarily set an axial distance between the heat roller and the pressure roller. A fixing device having an inter-axis distance adjusting function. 2. The fixing device according to claim 1, wherein the heat roller driving unit has a high-speed rotation control function of rotating the heat roller at a high speed. A lever mechanism for pressing the pressure roller toward the heat roller, a cam mechanism for urging the operation of the lever mechanism, and a stepping motor for controlling the operation of the cam mechanism. The fixing device according to claim 1, wherein the fixing device comprises: