JPS61236578A - Controlling method for fixing heater - Google Patents

Abstract

PURPOSE:To prevent securely a defect in fixation due to a drop in the temperature of a heat roller by heating some of plural fixing heaters forcibly until the end of exposing operation. CONSTITUTION:A microcomputer 34 controls a heater control circuit 35 on the basis of the detected temperature of the heat roller in exposing operation and an exposing operation indication signal. Consequently, if the heater 12, which has such capacity that an abnormal rise in temperature is caused, of the temperature of the heat roller attains to set temperature before the start of the exposing operation, one of plural, e.g. two fixing rollers 12 and 13 is heated forcibly until the end of the exposing operation. The heating of the fixing heater is controlled even during this exposing operation to prevent securely a defect in fixation due to a drop in the temperature of the heating rollers even when copying machine is long.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fixing heater control method, and more specifically, to reliably prevent a heating roller from falling below a predetermined set temperature during a copying operation. The present invention relates to a fixing heater control method.

<Prior Art> Conventionally, there has been a fixing heater control method in which the fixing heater for fixing is not controlled at all during the exposure operation.

<Problems to be Solved by the Invention> Since the configuration described above does not perform ON-OFF control of the heater during the exposure operation, it is different from the configuration that performs ON-OFF control of the fixing heater during the exposure operation. Unlike this, it is possible to reliably prevent the occurrence of speed fluctuations in the drive system of the copying machine due to voltage drop due to the influence of inrush current, and there is no problem such as blurred images, but this is especially true when the copy paper is long. This method has the disadvantage that the temperature of the heating roller decreases when a sheet of copy paper is fixed, resulting in defective fixing.

This invention was made in view of the above problems,
It is an object of the present invention to provide a fixing heater control method that can reliably eliminate image blurring and also reliably eliminate the occurrence of fixing failure.

Means for Solving the Problems> In order to achieve the above object, the fixing heater control method of the present invention is such that when the temperature of the heating roller reaches a predetermined set temperature before the start of the exposure operation, This is to forcibly generate heat from the fixing heater in the section until the end of the exposure operation.

However, it is preferable to use a part of the fixing heater that has a heat generating capacity that will not cause the heating roller to become abnormally heated.

<Function> With the method described above, if the temperature of the heating roller has reached the predetermined set temperature before the start of the exposure operation, power consumption in the fixing device can be reduced by energizing only some of the heaters. By suppressing the amount of heat generated and causing some of the heaters to generate heat continuously, the speed of the drive system of the copying machine main body can be kept constant.

If some of the heaters do not abnormally raise the temperature of the heating roller, it is possible to compensate for abnormal heat absorption by the copy paper.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a sectional view showing the fixing device, which includes a heating roller (1) and a pressure roller (2) that are pressed against each other and rotate in opposite directions.

The heating roller (1) has two fixing heaters (12) (1
3) is installed. The pressure roller (2) has a surface FIJ made of silicone rubber etc. around the cylindrical body (21).
(22) is installed.

Note that (31) is a guide that ensures that the copy paper is guided between the heating roller (1) and the pressure roller (2), and (32) is a guide that ensures that the copy paper after fixing is guided from the heating roller (1). It is a separation claw for peeling, and (33) is a temperature detection element for detecting the temperature of the heating roller (1).

FIG. 2 is a block diagram for implementing the fixing heater control method, in which an exposure operation instruction signal and a detected temperature signal from the temperature detection element (33) are applied to the microcomputer (34), and A control signal is applied to the heater control circuit (35), and the heater control circuit (3
5), the power to the fixing heaters (12) and (13) is set to 0N.
-OFFIIJtll.

With the above configuration, when no exposure operation is being performed and during warm-up or wait, the re-fixing heater (12) is activated based on the temperature of the heating roller (1) detected by the temperature detection element (33). (13) 0N-OFF
At times other than the above, one of the fixing heaters (the fixing heater with a larger heat generating capacity) is set to 0N- based on the temperature of the heating roller (1) detected by the temperature detection element (33).
The heating roller (1) and the pressure roller (
2) can be maintained at a predetermined set temperature.

In addition, when performing an exposure operation, the temperature detection element (3) detects that the heating roller (1) has reached a predetermined set temperature.
3), and by forcibly continuing to energize one of the fixing heaters (12) and driving an optical system (not shown), the document is exposed to light and a toner image faithful to the document image is formed. After being transferred onto the copy paper, the copy paper can be guided between a heating roller (1) and a pressure roller (2) to fix the toner image. In this case, especially if large-sized copy paper is used and a large number of sheets are copied continuously, the amount of heat taken away from the heating roller (1) will increase, and the temperature of the heating roller (1) will increase. However, since the fixing heater (12) is forcibly energized, a drop in temperature can be reliably prevented and good fixing performance can be achieved.

In the above embodiment, the fixing heaters (12) (13)
The heat generating capacity of the heating roller (
1), it is possible to prevent the temperature from decreasing, and it is also possible to reliably prevent an abnormal temperature rise of the heating roller (1).

<Effects of the Invention> As described above, the present invention has the unique effect of reliably preventing the temperature of the heating roller J3 from decreasing during the exposure operation and exhibiting good fixing performance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a fixing device, and FIG. 2 is a block diagram for implementing a fixing heater control method.

Claims (1)

[Claims] 1. Connect the heating roller for fixing to two or more heaters. The fusing heater control method uses a heater to control heating. In some cases, the temperature of the heating roller may exceed the exposure of the original. The predetermined set temperature is reached before starting operation. If the exposure movement of some heaters is Forcibly generate heat until the end of production A fixing heater control method characterized by: 2. Some heaters were forced to generate heat. The temperature of the heating roller rises abnormally under certain conditions. The above feature has an unprecedented heat generation capacity. Fixing heater system according to claim 1 Your method.