JPH10143002A - Fixing machine for electrophotographic device, and fixing roll for the fixing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability of an electrophotographic device by enhancing the accuracy of the temp. control of a fixing roll, to eliminate a failure in fixing such as an offset, in a fixing machine for detecting the, temp. of the fixing roll with an infrared thermometer, in the electrophotographic device and the fixing roll for the fixing machine. SOLUTION: The surface temp. of the fixing roll 1 is detected by the infrared thermometer 9. When the surface temp. of the fixing roll 1 is controlled to be within a fixing temperature range, a symbol or character corresponding to the emissivily of the surface of the fixing roll 1 measured from the outside of the fixing roll 1 is displayed in a part of the fixing roll 1, the emissivity of the display is read by a detecting part 6 and used as a correction value, to correct, a detected temp. in an infrared temp. and the actual temp. of the surface of the fixing roll 1 and the temp. detected by the infrared thermometer 9 are made equal to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic fixing machine for detecting the temperature of a fixing roll in an image forming apparatus such as an electrophotographic copying machine or a printer with an infrared thermometer, and to a fixing roll for the same.

[0002]

2. Description of the Related Art FIGS. 5 and 6 illustrate a conventional example.

[0003] In the image formation of an electrophotographic apparatus, that is, in a printing process, one method of heating and fixing a toner image electrostatically transferred on a printing paper surface is to fix a toner image between a fixing roll and a pressure roll. A heating and pressurizing method for passing a sheet through a sheet is known, and has conventionally been used in a fixing machine such as a copying machine and a printer.

In order to obtain a good fixed image by the fixing device, it is necessary to detect and control the temperature of the fixing roll.

[0005] As the temperature detecting means, a temperature detection by a thermistor 12 or an infrared thermometer 9 is known.

Thermistor 12 fixed to holding component 14
Is in contact with the fixing roll 1 via the heat-resistant film 13 to detect the temperature.

[0007] The infrared thermometer 9 is a non-contact fixing roll 1
The surface temperature of the fixing roll 1 is detected by the control unit 11.
The surface temperature of the fixing roll 1 is maintained at the fixing temperature by turning on and off a heater lamp (not shown) in the inside.

However, when the temperature is detected by the thermistor 12, the toner adhered to the fixing roll 1 during printing accumulates between the surface of the fixing roll 1 and the heat-resistant film 13, and the surface of the fixing roll 1 is worn. Therefore, the thermistor 12
Is often used in a fixing machine for an electrophotographic apparatus having a low printing speed.

On the other hand, since the infrared thermometer 9 is not in contact with the fixing roll 1, there is no influence on the fixing roll 1. Therefore, the temperature detection by the infrared thermometer 9 is often used for a high-speed fixing device for an electrophotographic apparatus.

[0010]

The printing speed of the electrophotographic apparatus has been increasing.

For this reason, an infrared thermometer is often used to detect the temperature of the fixing roll of the fixing machine for the reasons described above.

However, the detection temperature of the infrared thermometer differs depending on the emissivity of the measured object even when the temperature of the measured object is constant.

The emissivity of the fixing roll is determined by measuring the material of the roll surface, the color of the release resin layer on the surface, the surface roughness, or the thickness (if the surface layer is thin, the emissivity of the surface of the aluminum cylinder below the surface layer) Is affected). For fixing rolls,
The releasable resin layer is worn and thinned by printing. Therefore, the emissivity changes.

As described above, the emissivity of the surface layer measured from the outside of the fixing roll may differ depending on the roll.

Therefore, even if the temperature of the surface layer of the fixing roll is the same, the temperature detected by the infrared thermometer differs depending on the fixing roll.

If the actual temperature of the fixing roll differs from the detected temperature, the temperature control range of the fixing roll (the temperature control range obtained by turning on and off the heater lamp inside the fixing roll) deviates from within the fixing temperature range. Offset (a phenomenon in which the toner on the sheet adheres to the fixing roll and adheres to the sheet again) may occur.

An object of the present invention is to improve the accuracy of the measurement and control of the temperature of a fixing roll and to eliminate a fixing defect such as an offset to enhance the reliability of an electrophotographic apparatus.

[0018]

An object of the present invention is to provide a fixing device for an electrophotographic apparatus, wherein the surface temperature of a fixing roll is detected by an infrared thermometer and the surface temperature of the fixing roll is controlled within a fixing temperature range. A symbol or a character corresponding to the emissivity of the fixing roll surface measured from the outside of the roll is displayed on a part of the fixing roll, the emissivity of the display is read by a detecting unit, and the detected value is used as a correction value for the infrared temperature of the control unit. This is achieved by correcting the detected temperature to make the actual temperature of the fixing roll surface equal to the detected temperature of the infrared thermometer.

As described above, by reading the display of the emissivity of the fixing roll, the detected temperature of the infrared thermometer is corrected, and the actual temperature of the surface of the fixing roll is made equal to the detected temperature of the infrared thermometer. Further, it is possible to enhance the accuracy of the temperature control of the fixing roll, eliminate the fixing defect such as offset, and enhance the reliability of the electrophotographic apparatus.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 explain an embodiment.

FIG. 1 shows the structure of the fixing device.

The pressure roll 2 is pressed against the fixing roll 1 with a constant load, and rotates at the same peripheral speed.

The fixing roll 1 is obtained by coating an aluminum cylinder 4 with a release resin 3 such as a fluororesin. Before shipment, a portion of the fixing roll 1 covered with the release resin 3 is radiated. Measure the rate.

The emissivity is as follows when the color of the release resin 3 is black.
It is close to 1 and is near 0.92 for gray. When the release resin 3 is thin, it may be smaller than 0.9 due to the effect of the emissivity of the aluminum cylinder 4. In this embodiment, the fixing roller 1 having a gray release resin 3 and an emissivity of 0.92 was used. The measured emissivity is converted into a symbol or a character and printed on the fixing roll 1.

FIG. 2 shows the conversion of the emissivity into a bar code 5,
A case where printing is performed on the fixing roll 1 is shown in an enlarged manner.

In FIG. 1, an infrared thermometer 9 is provided to face the releasing resin 3 of the fixing roll 1. Also,
The detection unit 6 faces the barcode 5 indicating the emissivity.

As shown in FIG. 3, the detecting unit 6 includes a light emitting unit 7
The light receiving unit 8 emits light, receives light reflected by the bar code 5, and reads the bar code 5 on the fixing roll 1.

The infrared thermometer 9 detects the surface temperature of the release resin 3 of the fixing roll 1. When the emissivity of the fixing roll 1 is 0.92, as shown in FIG.
Actual temperature of fixing roll surface (measured by contact thermometer)
On the other hand, the detection temperature of the infrared thermometer 9 shows a low value (when the actual temperature is about 200 ° C., the temperature of the infrared thermometer is about 190 ° C.).

For this reason, the control unit 10 corrects the temperature detected by the infrared thermometer 9 based on the emissivity value read by the detection unit 6 as shown in FIG. The detected temperatures of the total 9 are made equal. As a result, the control temperature can be maintained at a fixing temperature of about 200 ° C., and a good fixed image can always be obtained during printing.

The emissivity of the display of the fixing roll 1 is an initial value, and as the number of prints increases, the release resin 3 becomes thinner and the emissivity decreases. FIG. 7 shows the relationship between the number of prints and the emissivity of the surface of the fixing roll when a printing experiment was performed with the fixing roll coated with the fluororesin PFA. The initial emissivity is 0.92 and 10
When printing 100,000 sheets, it becomes 0.89. Therefore, based on this, the value of the display emissivity is corrected according to the number of prints.
As a result, the control temperature can be maintained at a fixing temperature of 180 to 200 ° C., and a good fixed image can be obtained when printing is performed with the fixing roll of this embodiment.

[0031]

According to the present invention, the display of the emissivity of the fixing roll is read, whereby the detected temperature of the infrared thermometer is corrected to make the actual temperature of the fixing roll surface equal to the detected temperature of the infrared thermometer. By doing so, the accuracy of the temperature control region of the fixing roll can be increased, and fixing defects such as offset can be eliminated, thereby improving the reliability of the electrophotographic apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a fixing device according to an embodiment.

FIG. 2 is a partially enlarged view showing the display of the emissivity of the fixing roll according to the embodiment.

FIG. 3 is a schematic diagram illustrating a detection unit for emissivity of a fixing roll according to an embodiment.

FIG. 4 is a graph showing a relationship between a detected temperature and a correction temperature of the infrared thermometer according to the embodiment.

FIG. 5 is a schematic diagram illustrating a temperature detection method using a conventional thermistor.

FIG. 6 is a schematic diagram illustrating a temperature detection method using a conventional infrared thermometer.

FIG. 7 is a graph showing a relationship between the number of printed sheets and the emissivity according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing roll, 2 ... Pressure roll, 3 ... Release resin, 4
... Aluminum cylinder, 5 ... Bar code, 6 ... Detector, 7 ... Light emitting unit, 8 ... Light receiving unit, 9 ... Infrared thermometer, 10 ... Control unit.

Claims (3)

[Claims] 1. A fixing device of an electrophotographic apparatus for detecting the surface temperature of a fixing roll with an infrared thermometer and controlling the surface temperature of the fixing roll within a fixing temperature range. A fixing roll that is expressed in characters and displayed on a part of the fixing roll, a detection unit that reads the emissivity, and a control unit that corrects a detection value by an infrared thermometer with the emissivity as a correction value and sets a detection temperature. A fixing device for an electrophotographic apparatus, wherein an actual temperature of a fixing roll surface is accurately detected. 2. A fixing device for an electrophotographic apparatus according to claim 1, further comprising a control unit for changing a correction value so as to reduce the emissivity in response to an increase in the number of printed sheets. 3. A fixing roll, wherein the emissivity of the surface of the fixing roll is indicated by a symbol or a character on a part of the surface.