JPS6155681A - Fixing device of copying machine - Google Patents

Abstract

PURPOSE:To perform good fixing by providing a temperature sensor so that this sensor can be moved in parallel with the axis of a heat roll and setting the peripheral temperature of the heat roll within an allowable temperature range. CONSTITUTION:A temperature sensor 8 is moved back and forth in the axial direction near a heat roll 2 to detect the temperature of the peripheral surface of the roll; and since a mountain-shaped temperature distribution where the center part of the roll 2 has the highest temperature is set by heating of a quarty lamp 4, the control temperature is set to a certain temperature, and the sensor 8 is placed in the center part to reduce uniformly the temperature distribution of the whole of the roll. If the sensor 8 is set in a position P1 in case of continuous fixing of small-sized forms b1 and is set in a position P2 in case of fixing of large-sized forms b2, peripheral temperatures of both end parts of the heat roll 2 are higher than a minimum fixing temperature to perform good fixing.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fixing device installed in a copying machine, etc., and more specifically, a fixing device that can fix both large-sized paper and small-sized paper well. Regarding.

[Conventional technology]

Generally, in the fixing device of a copying machine, a heat source such as a cork lamp is installed 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 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 heat supplied from the cork lamp.

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

Conventionally, the following method has been used to detect the temperature of the circumferential surface of a heating roll for temperature control.

(i) One cork lamp is equipped as a heat source for the heating roll, and one temperature sensor detects the light emission temperature of the one cork lamp.

(11) Equipped with multiple cork lamps as a heat source for the heating roll, and one temperature sensor detects the emission temperature of the multiple cork lamps.

(iii) A single cork lamp is provided as a heat source for the heating roll, and a plurality of temperature sensors detect the light emitting temperature of the single cork lamp.

(iv) A plurality of cork lamps are provided as heat sources for the heating roll, and a plurality of temperature sensors detect the light emission temperature of the plurality of cork lamps.

[Problem that the invention seeks to solve]

The above conventional methods each have the following problems.

That is, in the case of (i) above, it is not possible to detect the temperature of the entire heating roll with only one temperature sensor because the temperature distribution is different between the center and both ends of the heating roll. It is difficult to achieve both good fixing performance for large-sized paper and suppression of temperature rise during continuous feeding of small-sized paper.

In the case of (ii) above, a plurality of cork lamps improves the set temperature distribution, but increases the cost and makes it impossible to completely detect the temperature.

In the cases (iii) and (iv) above, temperature detection can be performed completely, but the cost is high.

The present invention has a simple structure, low cost, and can completely detect the temperature of the heating roll with consistent detection values, set the circular surface temperature of the heating roll within the allowable fixing temperature range, and perform good fixing. The object of the present invention is to provide a fixing device for a copying machine that has a temperature sensor and a heat source.

[Means and effects for solving the problem] The present invention detects the optimal peripheral surface temperature for adjusting the temperature according to each paper size by moving parallel to the axis of the heating roll near the heating roll. A temperature sensor is installed to completely detect the temperature of the heating roll with a consistent detection value, and the peripheral surface temperature of the heating roll is set within the allowable fixing temperature range to ensure good fusing. It is.

〔Example〕

The present invention will be explained below based on embodiments shown in the drawings.

In FIGS. 1, 2, and 3, (1) is a fixing device, which is composed of a heating roll (2) and a pressure roll (3). The heating roll (2) is equipped with one cork lamp (4) as a heat source inside, and a heat-resistant elastic body (5) is provided on the peripheral surface.
) is coated. Further, the circumferential surface of the pressure roll (3) is also coated with a heat-resistant elastic body (6). The heating roll (2) and the pressure roll (3) are in pressure contact with each other to form a nip (N), and the paper on which the toner image (a) has been transferred is passed through this nip (N). As a result, the toner image (a) is fixed by heat fusing. Note that (7) is a peeling claw that peels off the paper after fixing.

Heat roll for heat fusion (2 liters of heat is consumed, so
The temperature of the circumferential surface of the heating roll (2) changes.

Therefore, a temperature sensor (8) is provided to detect the temperature of the circumferential surface of the heating roll (2). This temperature sensor (8
) is configured to be able to reciprocate near the heating roll (2) in the axial direction of the heating roll (2), and the heating roll (2)
It is now possible to detect the temperature of any peripheral surface of the That is, as shown in FIG. 3, the temperature sensor (8) connects a belt (11) to a pulley (9) and aω that are installed at two points parallel to the same axis near the shaft end of the heating roll (2). It is stretched and attached to the same belt (11). A morph (M) is attached to one of the above-mentioned boots, and the temperature sensor (8) moves back and forth while maintaining a constant distance from the heating roll (2) by driving the same machine (M). conduct.

As shown in FIG. 40, the temperature distribution due to heating by the cork lamp (4) is a mountain-shaped temperature distribution pattern with the highest temperature at the center of the heating roll (2). Therefore, by setting the control temperature (Tc) to a constant temperature and placing the temperature sensor (8) closer to the center, the temperature distribution of the entire heating roll (2) can be uniformly lowered.

Therefore, when fusing is performed by continuously feeding small size paper (bl), if the temperature sensor (8) is set to the sensor position (Pl), the temperature of the circumferential surface at both ends of the heating roll (2) will increase. can be suppressed (diagram (Ll)). Furthermore, when fusing large size paper (b2), by setting the temperature sensor (8) to the sensor position (P2), the circumferential surface temperature of both ends of the heating roll (2) can be adjusted to the minimum fusing temperature (T process). ) can be done as follows, and will not cause fixing failure (line diagram (L2
) ).

When the paper is not passing, the temperature sensor (8) is set to the sensor position (p3>) and the heating roll (2) is heated to the optimum state (diagram (L3)) to make each paper ready for fixing. After turning on the paper feed switch, the temperature sensor (8) is moved to the sensor position (Pl) or (P2) for each size paper to perform fixing.

Note that the temperature of the peripheral surface of the heating coal [2] is set not to exceed the hot off-cent temperature (To) due to the unique light emission pattern of the cork lamp (4).

C) Effects of the Invention As explained above, according to the present invention, the structure is simple, so costs can be reduced, and temperature can be detected with one temperature sensor, so the detected value is lower than when multiple temperature sensors are used. Since there is no variation in temperature and accurate temperature detection is possible, and the optimum temperature distribution #Tj can be adjusted for each size of paper, there is an effect that good fixing can be performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional plan view of an embodiment of the present invention, FIG. 2 is a sectional side view thereof, FIG. 3 is a front view thereof, and FIG. 4 is a circumferential temperature distribution diagram of a heating roll. (1): Fixing device (2): Heating roll (3)
: Pressure roll (4): Cork lamp +51.
(61: Heat-resistant elastic body (7): Peeling claw (8): Temperature sensor +9), GO): Pulley (11): Belt (M): Morph (N): Nip part (To)
: Hot off-cent temperature (Tc) : Control temperature (T1) : Minimum fixing temperature (al : L-ner image

Claims (1)

[Claims] 1. A temperature sensor is provided near the circumferential surface of a heating roll having an internal heat source to detect the optimum circumferential surface temperature for temperature adjustment according to each paper size, and is movable in parallel to the axis of the heating roll. A fixing device for a copying machine characterized by: