JPS6134573A - Heat-fixing device of electrophotographic copying machine, etc. - Google Patents

Abstract

PURPOSE:To improve the thermal efficiency of an entire heat-fixing device, by forming a pressure roller paired with a heat roller by covering the surface fo a heat pipe with an elastic member high in thermal conductivity and positioning the pressure roller below the heat roller. CONSTITUTION:When power supply is turned on, a heater 1 lights and heats up a heat roller 2. During a fixing operation, the heat roller 2 and a pressure roller 3 are turned under a pressure-contacted condition and, when the rollers 2 and 3 rotate, a solvent 4 contained in the heat pipe 5 of the roller 3 thoroughly wets the inner wall of the heat pipe 5 and the heat pipe 5 sufficiently exerts its capability as a heat pipe. When fixing a small-sized paper for example, the temperature at the end sections of the roller 2 where the paper does not pass through is absorbed by the solvent 4 and occurrence of an abnormally high temperature is prevented and the heat energy absorbed by the solvent 4 is transferred to the paper passing section of the roller 2 so as to rise the temperature at the paper passing section. Therefore, operations are made to improve the fixing efficiency through an elastic member 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat fixing device in an electrophotographic copying machine or the like. .

(Prior Art) Conventionally, a fixing device used in an electrophotographic copying machine, etc. has a fixing device that is required when a sheet of paper onto which an unfixed toner image has been transferred passes between two pressure rollers provided in a pair above and below. The cold pressure fixing method fixes the image by applying pressure, and the other uses thermal energy such as infrared rays or fludge from near above the paper onto which the unfixed toner image has been transferred, and fixes the image using thermal energy. A heat radiation fixing method such as radiant or flash is used for fixing, and a predetermined heat energy is applied to the dazzling paper when the paper is passed between a pair of upper and lower rollers and a pressure roller. There was a heat/p-ra system in which image fixation was carried out by applying pressure and pressure.

(Problem to be Solved by the Invention) However, when trying to shorten the warm-up time and increase the fixing speed with these fixing devices, in the case of the cold pressure fixing method, it is necessary to prevent the paper and toner from becoming glossy. There are drawbacks such as the lack of a suitable thermal agent at present, and the drawbacks of the radiant and fludge heat radiation methods include poor thermal efficiency and unsuitability for high-speed copying machines, etc.; Conventional adhesives can be used as the adhesive, and since they have excellent thermal efficiency, it is possible to shorten the warm-up time by reducing the thickness of the heat roller, but when fusing paper of various sizes. ,
Eliminates problems such as a sharp temperature gradient occurring in the axial direction of the rollers, shortening the lifespan of both the heat roller and pressure roller, as well as the lifespan of parts surrounding these rollers, as well as offset of fixed toner images. There were some drawbacks, such as not being able to do it.

(Means and effects for solving the problem) The present invention has been made to eliminate the drawbacks of the conventional fixing device described above, and in order to shorten the warm-up time of the fixing device and increase the fixing speed. In a heat roller fixing device in which the heat roller has a thinner wall thickness to reduce its heat capacity, a pressure roller paired with the heat roller has a heat pipe as its core and its surface is covered with an elastic member with high thermal conductivity. and arranging the pressure roller below the heat roller.
Prevents temperature rise at the edge of the roller when fixing small-sized paper, etc., thereby shortening the life of the ρ-ra and the life of peripheral parts of the roller, as well as fixing failure at the edge of the paper and offset of the fixed toner image. It is designed to solve problems such as:

(Example) The present invention will be described in detail below based on an example shown in the drawings.

The figure is a sectional side view showing an embodiment of the heat fixing device in an electrophotographic copying machine or the like according to the present invention.

In the figure, a heat pipe 2 containing a heater 1 and a pressure ρ-ra 3 are rotatably attached between two support frames (not shown). The pressure ruler 2 uses a thin-walled heat roller in order to reduce heat capacity and shorten warm-up time. A pipe 5 is used as a core and the surface of the pipe 5 is coated with a highly thermally conductive elastic member 6 such as a rubber material or synthetic rubber mixed with a heat conductive substance, and the pressure roller 3 is placed under the heat ruler 2. Place it in pressure contact.

The present invention is constructed as described above. Next, its operation will be explained.

First, when the power is turned on, the heater 1 in the heat roller 2 is turned on to warm up the am and - rollers 2. Thermal energy used to warm up the heat pipe 22 is supplied to the pressure pipe which has the heat pipe 5 built-in.
Since the heating roller 3 is located below the heat roller 20, the heat pipe control function cannot be fully exerted at this point, and therefore the heating roller 2 is heated efficiently.

Next, during the fixing operation, the heat roller 2 and the pressure roller 3 rotate while in pressure contact, and this rotation causes the solvent 4 stored in the heat pipe 5 of the pressure roller 3 to corner the inner wall. For example, when fixing small-sized paper, the temperature at the end of the heat pipe 2 outside the paper feeding area may rise abnormally. Even if the pressure roller 3 corresponding to the pressure roller 3 absorbs the thermal energy at the location into the solvent 4 in the heat pipe 5 through the elastic member 6, the temperature is lowered, and the thermal energy absorbed by the solvent 4 is The paper is moved to the low-temperature side of the paper passing section in the heat pipe 5 and held therein, thereby preventing an adverse effect on parts around the end of the heat roller 2. The retained thermal energy is used to heat the back side of the paper via the elastic member 6, contributing to improving the fixing efficiency.

(Effects of the Invention) The present invention achieves and operates as described in item 5 above, and is achieved by reducing the thickness of the heat ruler 2 in order to shorten the warm-up time of the fixing device.
A heat pipe 5 installed in the core of the pressure roller 3 is used to prevent the temperature gradient generated in the axial direction of the pressure roller 2, which is the cause of toner offset and poor fixing at the edges of the paper.
At the same time, in order to achieve this uniformity, the thermal energy collected in the heat pipe 5 is used to heat the back side of the paper at the paper passing section of the roller via the elastic member 6 with excellent heat conductivity. This has the effect that the thermal efficiency of the fixing device itself can be further improved.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing an embodiment of a main part of a heat fixing device in an electrophotographic copying machine or the like according to the present invention. In the diagram, 1... Heater, 2... Heat pipe, 3...
・Pressure 1-ra, 4...Solvent. 5...Heat pipe. 6...Elastic member.

Claims (1)

[Claims] In a heat roller type fixing device, a heat pipe whose surface is coated with an elastic member with excellent thermal conductivity is used as a pressure roller paired with the heat roller, and the pressure roller is disposed below the heat roller. A heat fixing device for an electrophotographic copying machine, etc., characterized by the following.