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AssigneeRicho Company, Ltd.
InventorsRyoichi Namiki, Yuichiro Higashi, Toshiyuki Kikuchi, Ichiro Fukushima, Yasuo Asahina, Setsuo Soga
Estimating the term…
Improved heat roller fixing apparatus comprising an inner cylinder having a heater therein, an outer cylinder, and a vacuum chamber which is formed between the inner cylinder and the outer cylinder and which contains a liquid heat transfer medium at low pressure is described. In particular, improvements obviating excessive heating of the inner cylinder are made by placing the heat transfer medium in the chamber so as to be in contact with the lower portion of the inner cylinder at least when said outer cylinder is stationary, or by mounting on the inner cylinder a member which serves to stir or pour the heating medium on the inner cylinder and also to transfer heat indirectly from the inner cylinder to the outer cylinder through the heating medium so that speedy evaporation of the heating medium and safe and stable fixing of images are accomplished.
In a heat fixing roller apparatus comprising an inner cylinder having a heater therein, an outer cylinder which is made integral with said inner cylinder at respective ends thereof, a vacuum chamber which is formed between said inner cylinder and said outer cylinder and which contains a heating medium, the improvement wherein a heat conductive means for conducting heat from said inner cylinder is disposed between said inner cylinder and said outer cylinder in contact with said inner cylinder, and the lower portion of said heat conductive means is immersed in said heating medium at least when said outer cylinder is stationary, said heat conductive means comprising an intermediate cylinder supported on said inner cylinder by a plurality of heat conductive support arms.
In a heat fixing roller apparatus comprising an inner cylinder having a heater therein, an outer cylinder which is made integral with said inner cylinder at respective ends thereof, a vacuum chamber which is formed between said inner cylinder and said outer cylinder and which contains a heating medium, the improvement wherein a heat conductive means for conducting heat from said inner cylinder is disposed between said inner cylinder and said outer cylinder in contact with said inner cylinder, and the lower portion of said heat conductive means is immersed in said heating medium at least when said outer cylinder is stationary, said heat conductive means comprising at least one ring which covers said inner cylinder loosely and is hung from said inner cylinder.
In a heat fixing roller apparatus comprising an inner cylinder having a heater therein, an outer cylinder which is made integral with said inner cylinder at respective ends thereof, a vacuum chamber which is formed between said inner cylinder and said outer cylinder and which contains a heating medium, the improvement wherein a heat conductive means for conducting heat from said inner cylinder is disposed between said inner cylinder and said outer cylinder in contact with said inner cylinder, and the lower portion of said heat conductive means is immersed in said heating medium at least when said outer cylinder is stationary, said heat conductive means comprising a coil which covers said inner cylinder loosely and is hung from said inner cylinder.
In a heat fixing roller apparatus comprising an inner cylinder having a heater therein, an outer cylinder which is made integral with said inner cylinder at respective ends thereof, a vacuum chamber which is formed between said inner cylinder and said outer cylinder and which contains a heating medium, the improvement wherein a heat conductive means for conducting heat from said inner cylinder is disposed between said inner cylinder and said outer cylinder in contact with said inner cylinder, and the lower portion of said heat conductive means is immersed in said heating medium at least when said outer cylinder is stationary, said heat conductive means comprising means for stirring said heating medium when said outer cylinder is rotated, said heat conductive means comprising a plurality of fins formed of a conductive plate material and whose ends on one side are attached to the outer surface of said inner cylinder and whose other ends are in contact with the inner surface of said outer cylinder, and wherein said stirring means comprises said fins being provided with apertures for allowing said heating medium to pass therethrough.
In a heat fixing roller apparatus comprising an inner cylinder having a heater therein, an outer cylinder which is made integral with said inner cylinder at respective ends thereof, a vaccum chamber which is formed between said inner cylinder and said outer cylinder and which contains a heating medium, the improvement wherein a heat conductive means for conducting heat from said inner cylinder is disposed between said inner cylinder and said outer cylinder in contact with said inner cylinder, and the lower portion of said heat conductive means is immersed in said heating medium at least when said outer cylinder is stationary, said heat conductive means comprising means for stirring said heating medium when said outer cylinder is rotated, said heat conductive means comprising a plurality of fins formed of a conductive plate material and whose opposite ends are in contact with the outer surface of said inner cylinder and the inner surface of said outer cylinder, and support means for connecting said fins together and wherein said stirring means comprises said fins being provided with apertures for allowing said heating medium to pass therethrough.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Using contact heat: structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating
Electrography
Term ended 18 Aug 1998 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to a heat roller fixing apparatus. In an electrophotographic copying machine or an electrostatic recording machine, a fixing apparatus for fixing images on a sheet or supporting material is incorporated. One example of such apparatus is a fixing roller for heat fusing the image.
In one conventional heat fixing apparatus, a pair of fixing rollers is provided, each having a chamber containing a heat transfer or heating medium, which is sealed therein and converted to saturated vapor by a heater incorporated within a cylinder inside the roller. The rollers are disposed in contact with each other and a sheet or supporting material having an image to be fixed thereon is fed between them and heated by the rollers so that the image is fixed by heat fusing.
In the above-mentioned fixing rollers, the temperatures of the surfaces of the respective rollers are detected by a temperature detecting means, such as a thermistor, disposed on the surfaces of the respective rollers, and a necessary command is given to control means for the heater so that the fixing temperature of the respective roller surfaces is determined. This sort of fixing apparatus, however, has the shortcoming that the heating medium sealed in the chamber of the fixing roller is small in quantity as shown in FIG. 1. As a result, such a small quantity of heat transfer medium lies at the bottom of each chamber, and its upper surface does not come in contact with the inner cylinder holding the heater therein when the respective rollers are stationary. Therefore, when the heaters are energized while the rollers are stationary, the respective inner cylinders are heated, but heat is not readily transferred to the heating medium, and accordingly not to the surface of the respective rollers as the heating medium is not in contact with the inner cylinder. Therefore, the temperature detecting means, which is disposed in contact with the surface of the respective rollers, does not detect the accurate temperature of the heat to be transferred from the inner cylinder, and it gives the control means of the heater a wrong command demanding more heat. As a result, the inner cylinder is heated excessively, causing a very dangerous situation of damaging the inner cylinder.
FIG. 1 is a schematic sectional side elevation of one example of the conventional fixing apparatus using a pair of heating rollers;
FIG. 2 is a schematic sectional side elevation of one of a pair of heating rollers employed in one embodiment of the fixing apparatus according to the present invention;
FIG. 2A is a front view, partly in section, of the embodiment shown in FIG. 2.
FIG. 2 is a schematic sectional side elevation of one of a pair of heating rollers employed in one embodiment of the fixing apparatus according to the invention. In the figure, an outer cylinder 1 is a heat conductive roller whose outer peripheral surface is covered with a material excellent in surface lubrication, such as silicone rubber. Inside the outer cylinder 1 is disposed an inner cylinder 3 having a heater 2 therein comprising a material with high electric resistance such as an infrared heater and nichrome wire. The inner cylinder 3 and the outer cylinder 1 are made integral at the respective lateral ends thereof and supported rotatably by a side plate 100 as shown in FIG. 2A.
Between the outer cylinder 1 and the inner cylinder 3 is formed a vacuum chamber 4 which is kept at low pressure. The vacuum chamber 4 contains a heating medium 5 comprising a liquid with comparatively high vapor pressure, such as water and alcohol. The quantity of the heating medium 5 is much as will come in contact with the lower peripheral surface of the inner cylinder 3 as shown in FIG. 2 when the heating roller is not being rotated and the temperature of the outer surface of the roller reaches a predetermined fixing temperature. Furthermore, a temperature detecting means 6, such as a thermistor, is disposed at an appropriate position on the outer cylinder and electrically connected with a heat control means, not shown, of the heater.
The heat roller fixing apparatus is constructed with a pair of the above-mentioned heating rollers in combination thereof with a belt which rotates in contact with the lower surface of the roller.