JPS6155676A - Fixing device of copying machine - Google Patents

Abstract

PURPOSE:To fix always images well on large and small forms by providing two fans on the axial extension of a heat roll having apertures in both end parts and moving heated air in the roll to heat end pats of the roll. CONSTITUTION:In case of fixing on forms, peripheral temperatures of a heat roll 2 are different by the form size. Fans 8 and 9 are provided in both ends of the shaft of the roll 2, and the internal heated air is moved through aperture parts 2a to heat end parts of the roll. The light emission pattern of quarty lamp 4 as a heat source is set in accordance with continuous fixing of small-sized forms, and fans 8 and 9 are stopped in case of continuous fixing of small-sized forms to suppress the rise of temperature in both end parts of the roll, and the peripheral temperature is adjusted to a value lower than the hot offset temperature in this case. In case of large-sized forms, fans 8 and 9 are rotated to heat both end parts to a min. fixing temperature or higher. Thus, images are fixed well on large and small forms to use the heat effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device disposed in a copying machine or the like, and more particularly to a fixing device that can effectively fix both large-sized and small-sized sheets.

[Conventional technology]

Generally, in a fixing device of a copying machine, a heat source such as a lamp is provided inside the heating roll, and the heating roll is heated to a predetermined temperature by the light emitted from the lamp, thereby supplying the heat necessary for fixing the toner image.

Then, the copy paper on which the toner image has been developed is passed through a nip between a heating roll and a pressure roll that rotate in pressure contact with each other, and fixing is performed using the heat supplied from the collapsible lamp.

Therefore, the amount of heat consumed from the circumferential surface of the heating roll for fixing is different between large-sized paper and small-sized paper. Therefore, it is necessary to adjust the temperature of the circumferential surface of the heating roll during fixing of large-sized paper and small-sized paper to a range of not less than the minimum fixing temperature and not more than the hot offset temperature.

Conventionally, in order to reduce the cost of the device, a single lamp was often installed as a heat source.

Appropriate temperature distribution of the temperature on the circumferential surface of the heating roll was achieved by a light emitting pattern of a cork lamp that heated the central part of the heating roll to a high temperature and the opposite ends to a low temperature. Figures 4 and 5 show the temperature distribution of the set temperatures.

[Problem that the invention seeks to solve]

The conventional structure described above has the following problems.

That is, when heating is performed as shown in the diagram (L4) in FIG. 4, when small size paper is continuously fed, the hot offset temperature (To ), resulting in poor fixing.

Therefore, if the heating roll is heated so that it is below the hot offset temperature (To) at both ends as shown in the diagram (L6) in Figure 5, the temperature distribution will be as shown in the diagram (Ll), with the lowest temperature at both ends. When the temperature falls below the fixing temperature (T1) and a large size paper is fixed, a fixing failure occurs.

In the present invention, the temperature is adjusted so that the peripheral surface temperature at both ends of the heating roll is equal to or higher than the minimum fixing temperature (T1) and equal to or lower than the hot offset temperature (To) in both cases of fixing large-sized paper and fixing small-sized paper. The object of the present invention is to provide a fixing device that can always perform good fixing.

[Means and effects for solving the problem] The present invention provides a heating roll that has openings at both ends and a heat source inside, and transfers heat by sucking heated air inside the heating roll along its axial length. A fan is provided to correct the temperature distribution on the circumferential surface of the heating roll by heating the circumferential surface of the end of the roll, and this allows the circumferential surface temperature at both ends to be adjusted to either fix large-size paper or fix small-size paper. In this case, the temperature is adjusted so that it is above the minimum fixing temperature and below the hot offset temperature, so that good fixing can always be performed.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

In FIGS. 1 and 2, (1) is a fixing device;
It consists of a heating roll (2) and a pressure roll (3). The heating roll (2) is equipped with one Kortz lamp (4) having a predetermined light emitting pattern as a heat source inside, the circumferential surface is covered with a heat-resistant elastic material (5), and openings (2) are provided at both ends.
a) has been established. Further, the pressure roll (3) side is also coated with a heat-resistant elastic body (6) on its peripheral surface. The heating roll (2) and the pressure roll (3) are in pressure contact with each other to form a nip (N), and the paper onto which the toner image (aJ has been transferred) passes through this nip (N). By doing this, the toner image (a) is fixed by heat fusion. Note that (7) is a peeling claw that peels off the paper after fixing.

Since the heat of the heating roll (2) is consumed for thermal fusing, the temperature distribution on the circumferential surface of the heating roll (2) is different when fusing large-sized paper and when fusing small-sized paper by continuous feeding. There is a difference.

Therefore, fans (8) and (9) are disposed near both ends of the heating roll (2) so that the temperature distribution of the circumferential surface of the heating roll (2) can be appropriately achieved.

In other words, when fixing large size paper, use the fan (8
) and (9) to blow the heated air inside the heating roll (2) through the opening (2a) to the fans (8) and (9).
) to heat both ends of the heating roll (2) to the minimum fixing temperature (
T1) Warm to above. Furthermore, when fusing is performed by continuously feeding small size paper, the fans (81, (9) are stopped to suppress the temperature rise at both ends of the heating roll (2).
Adjust so that the peripheral surface temperature does not exceed the hot offset temperature (To).

That is, as shown in Fig. 3, when small size paper is continuously fed and fixed, the temperature of the circumferential surface at both ends of the heating roll (2) rises, but the temperature is kept below the hot offset temperature (To). The light emission pattern of the Colts lamp (4) is set in advance (diagram (Ll)). With this unique light emitting pattern, the temperature distribution on the circumferential surface of the heating roll (2) when using non-standard paper is as shown in the diagram (L2), and both ends are at the lowest fixing temperature (T
s) below. Therefore, by rotating the fans (8) and (9), the heated air inside the heating roll (2) warms the circumferential surface temperature of both ends to the minimum fixing temperature (T1) or higher, and Correct the light emission pattern and adjust it for good fixing. At this time, the peripheral surface temperature distribution changes as shown in the diagram (L3), and the peripheral surface temperature at both ends becomes equal to or higher than the minimum fixing temperature (Tl).

When fusing small-sized paper by continuously feeding it, the fans (8) and (9) are stopped to suppress the temperature rise at both ends of the heating roll (2), so the temperature distribution on the circumferential surface is linear as described above. Figure (Ll) is shown. In the figure, (11) is the width of the small size paper, (12) is the width of the large size paper, and (P) is the measurement point on the circumferential surface of the heating roll.

〔Effect of the invention〕

As described above, according to the present invention, the light emitting pattern of the heat source can be set in accordance with the fixing of small size paper by continuous feeding, and both ends of the heating roll can be heated. This has the effect of suppressing the temperature rise in the area, fixing large size paper well, and reducing costs by effectively utilizing heat.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional plan view of an embodiment of the present invention, Fig. 2 is a side view of the same cross-section, Fig. 3 is a circumferential temperature distribution diagram of a heating roll, and Figs. 4 and 5 are heating in a conventional example. It is a peripheral surface temperature distribution diagram of a roll. (ln: Fixing device (2): Heating roll (2a
): Opening (3): Pressure roll (4):
Coltz lamp (5), (6): Heat-resistant elastic body (
7): Peeling claw (8), (9): Fan (N): Nimp part (
To): Photo offset temperature (T1): Minimum fixing temperature (a):) Image patent applicant Fuji Xerox Co., Ltd. agent Masu Tegori (one idiot) Figure 2

Claims (1)

[Claims] 1. A heating roll with a heat source inside has openings at both ends, and is provided on the axis extension of both ends of the heating roll, and the heated air inside the heating roll is sucked to transfer heat, and the heating roll is heated. A fixing device for a copying machine, comprising: a fan that corrects the temperature distribution on the circumferential surface of the heating roll by heating the circumferential surface of the end portion.