JPH02300776A - Fixing device - Google Patents

Abstract

PURPOSE:To decrease heat loss, to reduce the quantity of variation of the lengthwise temperature distribution on the surface of a heat roller depending upon the width of a base, and to secure uniform fixation performance by recessing at least part of the internal wall of a heat roller heat insulating member inside below the end surface of the heat roller. CONSTITUTION:The heat roller heat insulating member 5 has part of its internal wall recessed inside below the end side of the heat roller 1 and also has a conic hole where a heat source 3 provided nearby the center of rotation of the heat roller 1 is passes. This structure reduces the quantity of radiating heat of convection and radiation from the internal surface and end surface of the heat roller 1 and also decreases the quantity of variation of the lengthwise temperature distribution with the width of passed paper, so even when a base which is a half as wide as maximum paper passing width is passed, the possibility that the temperature of the base non-passing part of the heat roller rises unnecessary to high temperature is reduced. Consequently, the uniform fixation performance is obtained irrelevantly to the width of the base and heat efficiency becomes high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for an electrostatic recording device or an electrophotographic recording device.

[Conventional technology]

As shown in FIG. 6, a conventional fixing device includes a heating roller 1 that rotates in pressure contact with a surface of a toner image support having an unfixed toner image, and a heating roller 1 that rotates in pressure contact with the surface of a toner image support having an unfixed toner image. A pressure roller 2 that is in contact with a surface that does not have an image and rotates in a driven manner; a heat source 3 that heats the heating roller 1 to a temperature higher than the toner melting point; and an end side of the heating roller 1 that covers the heating roller 1 and the heat source 3. It had a structure in which a heating roller heat insulating member 5 was provided.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, the amount of heat dissipated by convection and radiation from the inner surface and end surface of the heating roller 1 is large, and the heat loss due to radiation leaking from the heat source 3 at the end of the heating roller 1 is large. It had the problem of low thermal efficiency.

Furthermore, in a normal fixing device, it is preferable that the temperature distribution on the heating roller 1 is uniform in order to obtain uniform fixing performance. In order to obtain a suitable temperature distribution, it is necessary to make the heat resistance distribution in the longitudinal direction of the heat source 3 extremely large on the end sides. As a result, heat loss due to convection and radiation from the inner surface and end surface of the heating roller 1, and heat loss from the heat source 3 at the end of the heating roller 1.
Since the heat loss due to the radiation leaking from the heating roller 1 becomes greater in the temperature distribution on the heating roller 1 than in the case where the temperature drop at the end side is allowed, there is a problem that the thermal efficiency of the entire fixing device u becomes even lower. Further, in the conventional fixing device, the heat source 3 has a longitudinal temperature distribution characteristic such that a uniform longitudinal temperature distribution can be obtained when the L-toner image support of the maximum width that the fixing device can pass passes through. is used, so when a support whose width is half of the maximum width that allows paper to pass through, the temperature of the portion of the heating roller 1 that does not pass through the support becomes higher than necessary, which is dangerous. The problem was that the heat loss increased accordingly.

Considering that two-thirds to three-quarters of the energy consumption in an electrophotographic recording device is consumed by the fixing device, it is important to improve the thermal efficiency of the fixing device. It should be recognized that the overall energy efficiency of the photographic recording device is greatly affected.

Therefore, the present invention is intended to solve the two-part problem, and its purpose is to provide a fixing device that can obtain uniform fixing performance regardless of the width of the support and has high thermal efficiency. be.

[Means to solve the problem]

The fixing device of the present invention includes a heating roller, a pressure roller that comes into pressure contact with the heating roller, a heat source that heats the heating roller, and a heating roller heat insulating member provided on an end side of the heating roller. It is characterized in that at least a part of the inner wall of the heat retaining member is inside the end surface of the heating roller.

〔Example〕

FIG. 1 is a sectional view of an embodiment of the present invention. The content of the present invention will be explained below with reference to FIG. An L-toner image support, onto which an unfixed toner image formed by an electrophotographic process of an electrophotographic recording device (not shown) or an electrostatic process of an electrostatic recording device, is transferred, is conveyed to the main fixing device. The toner image support body is heated to a temperature higher than the toner melting point by a heat source 3, and is driven by a heating roller drive means (not shown), which rotates once through a heating roller gear 7, and a pressure spring is attached to the heating roller 1. 10, the nip formed by the pressure roller 2 is brought into pressure contact with the heating roller 2. Pass by side. At this time, the unfixed J-toner image is melted by heat supplied from the heating roller 1, fused to the toner image support, and further fixed to the toner image support by natural cooling after passing through the nip. In this embodiment, the heat source 3 is a rod-shaped halogen lamp supported by an electrode 4 provided on a heating roller heat insulating member 5 which also serves as an electrode stand, and the surface temperature of the heating roller is controlled by a temperature control device (not shown). Electric power is intermittently supplied through the electrode 4 while the temperature is within a certain temperature range. Here, the heating roller heat retaining member 5 has a shape in which a part of the inner wall extends 10 mm inward from the end side of the heating roller 1 through a gap of about 1 mm between the inner diameter of the heating roller 1, and further The heating roller 1 has a conical hole provided near the center of rotation for passing the heat source 3 therethrough. Here, the insulator portion 3b of the heat source 3 of this embodiment has a gap of about 0.5 mm with the hole of the heating roller heat insulating member 5. The heating roller heat retaining member 5 of this embodiment is made of heat-resistant non-conductive plastic, such as PET, PPS, PBT, fluororesin, etc.

With the above structure, the amount of heat dissipated by convection and radiation from the inner surface and end surface of the heating roller l is reduced, and heat loss due to radiant heat emitted from the heat source 3 is also reduced, and the thermal efficiency of the fixing device is improved. FIG. 3 shows the longitudinal temperature distribution A of the heat source 3 of the fixing device of this embodiment and the heating roller heat insulating member 5 of the conventional JTQ construction. ! indicates the heat distribution B in the longitudinal direction of the heat source necessary to realize a temperature distribution equivalent to that of this embodiment when paper passes through a support having the maximum width that allows paper to pass through in a fixing device having the same dimensions and shape as those of this embodiment. FIG. 4 shows the longitudinal temperature distribution C when letter paper is passed through an envelope having a width approximately half of the letter size in this embodiment, which has a heat source 3 whose longitudinal heat distribution is shown in FIG. 3A. The temperature distribution in the longitudinal direction is shown when a sheet is passed through the center of the width of the heating roller 1. FIG. 5 shows a longitudinal temperature distribution E when the letter paper is passed through a fixing device having a heating roller heat insulating member according to the prior art and a corresponding heat source having the longitudinal heat resistance distribution characteristics of FIG. 3. shows the longitudinal temperature distribution F when the envelope is passed through. A comparison between FIG. 4 and FIG. 5 shows that in this embodiment, the amount of variation in longitudinal temperature distribution depending on the width of paper passing through is smaller than in the prior art, and even when a support whose width is half the maximum paper passing width passes through the paper. It can be seen that the risk of the temperature of the part of the heating roller that does not pass through the support body becoming higher than necessary is reduced.

The heating roller heat insulating member of this embodiment and the prior art and the heating port
The average energy consumption when continuously fixing letter paper at a speed of 10 sheets per minute in each fixing device having a heat source corresponding to the heat insulating member was approximately 260 W in the conventional technology, whereas in this example This required approximately 220W. From the experimental facts, it can be seen that the fixing device of the present invention has clearly improved thermal efficiency compared to the fixing device of the prior art.

Furthermore, warm-up time has been shortened due to improved thermal efficiency.

Furthermore, in this embodiment, a part of the inner wall of the heating roller heat insulating member 5 enters inside from the end side of the heating roller 1, and the heat source 3
By having a conical hole for passing through, the heat source 3 can be easily attached when assembling the fixing device.

FIG. 2 shows another embodiment according to the invention. In this embodiment, the heating roller heat insulating member 5 covers the end of the heating roller 1 in the longitudinal direction and does not cover the outer circumferential direction, but the inner wall of the heating roller heat insulating member 5 does not enter inside the heating roller 1. It has a structure. Since the heating roller heat retaining member 5 does not also serve as an electrode stand, it may be made of not only heat-resistant non-conductive plastic, but also metal, heat-resistant conductive plastic, or a composite of these materials.

〔Effect of the invention〕

As described above, according to the present invention, in a fixing device that includes a heating roller, a pressure roller that comes into pressure contact with the heating roller, a heat source that heats the heating roller, and a heating roller heat-retaining member provided on the end side of the heating roller, By having a structure in which at least a portion of the inner wall of the heating roller heat retaining member is located inside the end surface of the heating roller, it is possible to realize a fixing device with low heat loss and high energy efficiency. Furthermore, the amount of change in longitudinal temperature distribution on the surface of the heating roller due to the width of the support passing through it is small, and uniform fixing performance is ensured. This has the effect of improving safety by eliminating the risk that the surface temperature of the heating roller in the area where the support does not pass when the support passes through the support, which is less than half the width of the support, will become abnormally high compared to the temperature during normal fixing. have

[Brief explanation of drawings]

FIG. 1 is a main sectional view showing the Ila configuration of an embodiment of the fixing device of the present invention. FIG. 2 is a main sectional view showing the configuration of another embodiment of the fixing device of the present invention. FIG. 3 is a diagram showing the heat distribution in the longitudinal direction of the heat source in an embodiment of the fixing device of the present invention and the heat distribution in the longitudinal direction of the heat source in the conventional technology. FIG. 4 is a diagram showing the temperature distribution in the longitudinal direction of the heating roller when it passes through the support in an embodiment of the fixing device of the present invention. FIG. 5 is a diagram showing the temperature distribution in the longitudinal direction of the heating roller when it passes through the support in the conventional fixing device. FIG. 6 is a main sectional view showing the configuration of a conventional fixing device. 1 is a heating roller, 2 is a pressure roller, 3 is a heat source, 4 is an electrode, 5 is a heating roller heat retaining member, 6 is a fixing device frame, 7
is a heating roller gear, 8 is a heating roller bearing, 9 is an elastic roller bearing, 10 is a pressure spring, 11 is an electrode stand, A is a longitudinal temperature distribution of the heat source in an embodiment of the fixing device of the present invention,
B is the heat distribution in the longitudinal direction of the heat source in the conventional technology, C is the temperature distribution in the longitudinal direction of the heating roller when passing through the support having the maximum paper width in an embodiment of the fixing device of the present invention, and D is the temperature distribution in the longitudinal direction of the heating roller in the embodiment of the fixing device of the present invention. In the example, the temperature distribution in the longitudinal direction of the heating roller when passing through the support half the width of the maximum paper passable width, E and F, are respectively:
Temperature distribution in the longitudinal direction of the heating roller when passing through the support at the maximum width and half width of the conventional technology. I"2

Claims (1)

[Claims] In a fixing device including a heating roller, a pressure roller that presses against the heating roller, a heat source that heats the heating roller, and a heating roller heat-insulating member provided on an end side of the heating roller, at least one of the inner walls of the heating roller heat-insulating member is provided. 1. A fixing device characterized in that a portion of the heating roller is inserted inside the end surface of the heating roller.