JP4115733B2 - Electrophotographic apparatus fixing apparatus and electrophotographic apparatus including the fixing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device such as an electrophotographic apparatus such as a copying machine or a printer.
[0002]
[Prior art]
In a fixing device in an electrophotographic apparatus such as a copying machine or a printer, oil is used to improve the releasability from toner and maintain the performance. In particular, in full-color electrophotographic apparatuses, a lot of oil is used in the fixing apparatus. In recent years, a fixing device using an endless belt is often used because of shortening of the warm-up time.
[0003]
Here, in the fixing device 1 using the endless belt 2 as shown in FIG. 3, the endless belt 2 stretched between the heating roll 3 and the fixing roll 4 is attached to the fixing roll 4 in order to improve the fixing property. When the pressure roller 5 is pressed at the outer peripheral position, the contact width of the endless belt 2 to the pressure roller 5 is increased, that is, the nip width (A + B width in the figure) is increased. The endless belt 2 is supported by the heating roller 3 and the fixing roller 4 and can be rotated endlessly. In the figure, R2 is a cleaning roller, 6 and 7 are heaters, and 8 is a thermistor.
[0004]
Here, in order to increase the nip width (A + B), the position of the heating roller 3 is lowered below the nip position between the fixing roller 4 and the pressure roller 5. Accordingly, when the oil is excessively supplied by the oil supply roller R1, the oil concentrates on the lowest point portion of the heating roller 3 and becomes an oil pool and hangs down to the fixing inlet guide plate 9, thereby causing an arrow. In the worst case, the oil adheres to the transfer paper conveyed in the direction, and in the worst case, the oil reaches the inside of the machine body or the machine body cannot be operated.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to prevent an oil pool from being generated due to an excessive supply of oil and prevent damage to an abnormal image and a machine body.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, an endless belt supported between the fixing roller and the heating roller, a pressure roller that presses the endless belt against the fixing roller to form a nip portion, and an oil for supplying oil to the endless belt An electrophotographic apparatus fixing device comprising an oil supply roller and a cleaning roller that is removed before an oil supply roller when unnecessary toner adheres to the endless belt, the cleaning roller, the oil supply roller, and the endless belt ; contact position of each of, Ri upper der than the highest point of the heating roller, and, characterized in that the lowest point of the heating roller is arranged so as to be above the nip position of the fixing roller and the pressure roller The fixing device of the electrophotographic apparatus is the main feature.
[0007]
The invention according to claim 2 is characterized in that the lowest point of the oil supply roller is located between the lowest point of the cleaning roller and the highest point of the heating roller. The main feature of the fixing device is the electrophotographic apparatus having the fixing device according to claim 1 or 2 .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 shows an example of an embodiment of the present invention. In the apparatus of FIG. 1, the lowest point 11 of the heating roller 3 is positioned above the nip position (A width position) between the fixing roller 4 and the pressure roller 5.
[0009]
Further, in the configuration of the fixing device in which the cleaning roller R2 and the oil supply roller R1 are arranged between the fixing roller 4 and the heating roller 3, the lowest point 14 of the cleaning roller R2 is higher than the uppermost point 13 of the heating roller 3. And has an inclined shape I. At this time, in the example of FIG. 1, the uppermost point 12 of the fixing roller 4 is the highest, the lowest point 14 of the cleaning roller R2 is next higher, the lowermost point 15 of the oil supply roller R1 is next higher, and the heating roller 3 The highest point 13 is the lowest.
[0010]
In the example of FIG. 1, the diameter of the fixing roller 4 is large in order to satisfy both the inclined shape I and the condition that the lowest point 11 of the heating roller 3 is positioned above the nip position (A width position). The diameter of the heating roller 3 is formed small.
[0011]
The inclined shape I prevents an oil reservoir from being formed on the cleaning roller R2, and further prevents an oil reservoir from being formed on the oil supply roller R1. Thereby, the occurrence of an abnormal image can be prevented. Further, since the lowest point 11 of the heating roller 3 is located above the nip position (width A position), even when oil is excessively supplied, the endless belt 2 is transmitted and indicated by a chain line arrow. In this way, oil flows to the pressure roller 5 and further flows to the oil pan 16 below the pressure roller 5, thereby preventing abnormal images and damage to the machine body.
[0012]
At this time, for example, as shown in FIG. 2, when the lowest point 14 of the cleaning roller R2 is located below the highest point 13 of the heating roller 3, an oil pool is generated in the cleaning roller R2 and the oil supply roller R1, and the oil supply Becomes unstable and an abnormal image such as uneven glossiness on the transfer paper is generated.
[0013]
As described above, according to the present invention, it is possible to prevent oil accumulation even when excessive supply of oil occurs, and it is possible to prevent abnormal images and damage to the machine body.
[0014]
【The invention's effect】
According to the present invention, even when an excessive supply of oil occurs, there is an effect that it is possible to prevent oil accumulation and prevent damage to an abnormal image and a machine body.
[Brief description of the drawings]
FIG. 1 is a cut side view showing an example of a form of a fixing device according to the present invention.
FIG. 2 is a cut side view for explaining a problem in the case of a configuration different from FIG.
FIG. 3 is a cut side view illustrating an example of a conventional fixing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixing device 2 Endless belt 3 Heating roller 4 Fixing roller 5 Pressure roller R1 Oil supply roller R2 Cleaning roller 12 Top point of fixing roller 13 Top point of heating roller 14 Bottom point of cleaning roller 15 Bottom point of oil supply roller

Claims (3)

An endless belt supported between the fixing roller and the heating roller, a pressure roller that presses the endless belt against the fixing roller to form a nip portion, an oil supply roller for supplying oil to the endless belt, and an endless belt a fixing device of an electrophotographic apparatus provided with a cleaning roller to remove before the oil supply roller when the unnecessary toner is attached, the contact position of each of the cleaning roller and the oil supply roller and the endless belt, heating Ri above der than the uppermost point of the roller, and, the lowest point of the heating roller, that are disposed so as to be above the nip position of the fixing roller and the pressure roller fixing device of an electrophotographic apparatus, wherein .   2. The fixing device for an electrophotographic apparatus according to claim 1, wherein the lowest point of the oil supply roller is located between the lowest point of the cleaning roller and the highest point of the heating roller. An electrophotographic apparatus comprising the fixing device according to claim 1.

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