JPS5934574A - Heating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating device, particularly a heating device equipped with a heating prevention function. explain.

The surface temperature of the upper heating element (for example, the fixing roller) which is heated by the Rogen heater (as a heat source in a conventional heat fixing device) is detected by a temperature detection means that is placed in contact with the fixing roller, and this detection signal is received. The temperature control circuit connects and disconnects the T switch inserted into the heater circuit to determine the temperature of the surface of the fixing roller.
'? It is controlled to keep it within an acceptable range.

However, if the Wr setting of the switch is not performed due to a failure of the temperature control circuit or the like, there is a risk that the fixing roller may be heated to an abnormally high temperature. Therefore, in order to prevent this excessive temperature rise r, a temperature fuse 1e as a thermally responsive member is provided close to the fixing roller, and this temperature fuse is inserted in series with the heater circuit.1. This temperature fuse receives heat from the fixing roller and blows out, thereby preventing the fixing roller from becoming excessively heated.

In this case, in the above procedure, connect the temperature fuse to the fixing roller 7D.
Therefore, we decided to place them close to each other while maintaining a certain distance.

This is due to the following reasons. That is, there is a distance-dependent temperature gap between the fixing roller and the temperature fuse.

For example, if the surface temperature of the fixing roller is 200'Q, then the constant NT''-ra is 1'B away from the π position, μm80 and 2.y.
g Disarticulation, *3rd position rated temperature (melting temperature) 168C
By arranging a temperature fuse, it will not blow out when the surface temperature of the fuser roller is normally controlled within the allowable range, and will prevent the fuser roller from overheating in the event of an abnormality, such as a failure of the temperature control circuit. Then, the above temperature and the temperature at the position of the use are 1
If the temperature exceeds 68C, the temperature fuse will melt and the power supply to the heating source can be cut off reliably. For this reason, the positional relationship between the temperature fuse and the fixing roller is important, and the position of the fixing roller due to thermal expansion is due to thermal expansion.
Efforts were made to reduce the number of changes.

Therefore, as mentioned above, if the temperature fuse is close to the fixing roller but located away from the circumferential surface of the fixing roller, a large current k will be turned off = 9 +
2! When using an anti-fuse, its own heat capacity is large and the thermal response a(
Therefore, the present invention solves the above-mentioned problems of the conventional example.

The present invention provides a heating device which can enhance thermal response and prevent excessive temperature rise of a heating source with rapid temperature changes.

An embodiment of the present invention will be described below.

FIG. 1 and FIG. 2 are longitudinal cross-sectional views of side ends of a heat fixing device and a heat fixing roller of a stilling machine to which an embodiment of the present invention is applied.

In the figure, reference numeral 1 denotes an aluminium-grade cylindrical fixing roller, which is rotatably held at both ends by receivers 2 and 2bK. The bearings 2a and 2bIa are attached to a support frame (not shown) of the fixing device.

The drive gear 15 is fixed to the fixing roller IKN, and the driving force from a drive source (not shown) on the side of the camera body is transmitted through the gear 14e on the side of the camera body. In order to maintain the position of the fixing roller 1 ['ff1 constant and prevent the bearings 2a and 2b from slipping or coming off, a C-ring is installed on the flange 1a provided only at the drive a end of the roller 1. This is a fixed shaft stop 16'a.

Further, the pressure roller 19 faces the fixing roller 1 under pressure,
It has a structure in which an elastic layer 18h of silicone rubber is applied to the surface of a core metal 20 made of stainless steel. Bearing 1 is attached to this core metal 20.
7a and 17bK are rotatably supported. A halogen heater 4 is provided inside the fixing roller 1 over substantially its entire width. The roller 1 is supported approximately at the center of the roller 1 by an electrode 3 attached to the frame 7, and is connected to a power source via the electrode 6 to be energized. The thermistor 5 is provided in contact with the surface of the fixing roller 1 to detect the surface temperature of the fixing roller 1. Temperature fuse 6 gen heater 40 Heat rays t'rJ7L emitted at a position where it can be sensed, and fixing roller 1 is attached to bearing 2, drive gear 15i - shaft stop 16 =p No measures are taken to prevent "slippage" in the longitudinal direction. side
The one on the side of the p-roller 1 having a larger rate of thermal expansion change is provided close to the end surface of the roller 1 in the first embodiment. This temperature fuse 6 is attached to the frame 7 and has a lead wire 13.
It is connected in series between the heater 4 and the power source 11 (Fig. ji3) through the heater 4 and the power source 11 (see Figure 3).

Here, the theoretical control of the roller 1 will be explained using FIG. 6.

First, the fixing roller 1u is supported by the pole 6 and heated by the heater 4. Then, according to the detection logic of the thermistor 5 which is brought into contact with the surface of the fixing roller 1 and serves as a temperature detection means, the temperature control circuit 10
2 is turned off to control the surface of the roller 1 to be maintained within the permissible range.

At this time, when the temperature control circuit 10 raises the vortex surface temperature of the roller 1 from the wind temperature to the temperature required for fixing, the rogen heater 4
is controlled to produce the maximum rated output.

Once the temperature necessary for fusing is reached, phase control is performed from then on! It is controlled so that it outputs a little more than 1J.

In the unlikely event that the fixing roller 1 generates heat above the specified temperature, the temperature fuse 6 will directly receive heat above the rated temperature and melt.

The supply of power to the heater 4 is immediately stopped. At this time, the fixing roller is made of metal with a large coefficient of thermal expansion and is made of metal with a large coefficient of thermal expansion. Because I want to be treated.

The distance between the fixing roller 1 and the fuse 6 whose position is fixed on the ground with the fixing device frame is @"ftm, and the fuse 6 is
The fixing roller 1J can be quickly exposed to thermal effects, and the temperature heat 6 can be quickly fused and eliminated in an abnormal state.

This process will be explained in more detail using FIG. 4.

The fixing roller 1 (the left end in Figure 1) is.

Since the drive gear 14 and the shaft stop 16 are regulated in position with the bearing 2a fixed to the J:9 fixing device frame (not shown), the free end of the fixing roller 1 (see Fig. 1 @ 4) is regulated. On the right-
) and the positional relationship with the fixing device frame body, which is uniquely determined by a minute error range (for example, a range of ±o, i m). That is,
When the fixing roller 1 is at room temperature (25°C), what is the temperature between the free end of the fixing roller and the temperature fuse 6? ! The relationship is IA-L
This means that l. and normal usage conditions (e.g. 1
800) When K is present, the 11th relationship is the thermal expansion VC in the axial direction of the fixing μm, which is IB, -Ll (IB-L
l>IA-Ll). In this state, the temperature fuse 6 is maintained so that it will not melt or change in quality even if it is affected by temperature under any normal usage conditions.
D-Ll'! -It's a decision.

Now, due to an accident such as a disconnection of the thermistor 5 for temperature control, the halogen heater 4, which is the F heating source, lights up continuously.

When the temperature of the fixing roller 1 rises abnormally, the fixing roller 1 thermally expands in the direction of the axis of the fixing roller σ and extends toward the unfixed free end side, that is, the side where the temperature humerus is disposed. That is, when the normal use condition F is at a very high temperature (for example, 350'C), the relationship between the temperature fuse 6 and the end surface of the fixing roller 1 is IC-Ll, and the distance between them is IC-Ll. This allows the temperature fuse 6 to receive the radiant heat of the fixing roller 1. For this reason, the time T1 until the temperature shift B melts
However, it is much shorter than the time T2 until the fuser roller 1 melts without taking into account the thermal expansion of the fixing roller 1 (TI<T2).
Become.

FIG. 5 is a graph showing the results of a comparative experiment of thermal responsiveness between an example of the present invention and a conventional example. In the experiment, we used a fixing roller made of aluminum with a wall thickness of 1.6 g, an outer diameter of 25 mm, and a length of 260 mm, and a 1.2 KW heater. installed inside. m carried out using the embodiment apparatus shown in FIGS. 1 to 5.

First, when the fixing roller was heated by applying AC ID0Vt to the halogen heater, the constant MI:I-A Shishiface temperature increased over time as shown in graph (6) in FIG. 5, and for about 18 seconds. On the other hand, a high-precision temperature fuse with a rating of 226° ± 1.610 was connected in series with a power supply I, and a 5A test was performed to continue supplying power assuming an abnormality. At the time of occurrence lQh et al. approx. 5
After 0fp, the fuse blows and the power supply to the halogen heater is cut off.

At this time, the distance between the end face of the fixing roller and the fuse is 2
At 00''C, the temperature of the fusing roller approaches 2.6 degrees, and the instantaneous temperature V of the fixing roller is approximately 550'QK to 9m, but the temperature is too low to μ to melt into the fixing roller.
shows the relationship between time (seconds) and the ambient temperature around the fuse, and is expressed in %.

Next, the conventional example is shown in Fig. 6, as shown in Figure 6.
A temperature fuse 6 is provided for the end surface of the fixing roller 1 and
The experiment was conducted using all fixing devices whose positional relationship with the fixing roller was designed so that it would not change due to thermal expansion of the fixing roller. As in the previous case, we continued supplying power to the heater in anticipation of an abnormality.The fuse was blown out approximately 70 seconds after the abnormality occurred. This shows the relationship between time and the ambient temperature around the fuse.

In the above embodiment, aluminum, which has a large coefficient of linear thermal expansion, is used as the material of the fixing roller.

Metals such as Tekken stainless steel, copper, and brass can also be used.

As described above, thermal expansion in the axial direction of the fixing roller 1 is utilized in the embodiments shown in FIGS. 1 to 5.

It is also possible to take advantage of the fact that the distance from a temperature fuse provided near the circumferential surface of the fixing roller 1 changes due to thermal expansion in the circumferential direction of the fixing roller 1, that is, a change in the outer diameter. In this case, by modifying the structure of the bearing, the fixing roller' can be stretched in a specific radial direction.

10- FIG. 7 shows an example of the above-mentioned narrow leaf blade, and the two-part bearing is made of materials having different coefficients of linear thermal expansion. The sliding member 24 of the 9 double bearings is made of a heat-resistant resin mixed with 4-fluoride chemical tin on the inner surface of the members 22 and 26.
9 For example, a mixture of polyamide resin and ethyl tetrafluoride ρλ
A cylindrical resin material with good sliding properties may be pasted.

If the member 23 is made of a material that expands thermally, the bearing of the fuser door roller 1 will have a greater degree of freedom in the vertical direction, and the fuser roller 1 [when heated, the fuser roller changes to the shape shown in Fig. 8]. As shown in the diagram, the bearing thermally expands into an elliptical cross-sectional shape (the member 22 thermally expands from pλ to the fixing roller by 1μ, and the bearing actively expands to the member 26IIIl), and its diameter is R1. If the #B bearing is installed with a temperature fuse close to the roller side on the member 26 side, the distance between the fixing roller and the temperature fuse will be shortened, and the temperature fuse will be It is possible to prevent excessive temperature rise by accelerating the fusing of the

In the above bearing, the member 22 is made of stainless steel, and the bearing is made of member 26K.
In an experiment using aluminum, there was a change in thermal expansion of R2-R1=1°0IIJlO in a bearing with an inner diameter of 25ψ.

FIG. 9 shows another example of the structure of the bearing, in which the sliding member 2
Divided into 7a and 27k12, each bearing is member 25-26.
Both bearings are placed in a frame 28 that can freely move up and down inside the members 25 and 26x, and a spring member 297 is inserted between the frame 28 and the bearings.

In this example as well, the bearing of the fixing roller 1 has a large degree of freedom in the vertical direction, and when the fixing roller is heated, the bearing pushes up against the spring force of the member 26r and the spring member 29, and the cross section becomes an ellipse. Thermal expansion into shape.

The same effects as in the examples shown in FIGS. 7 and 8 can be obtained.

Note that the temperature fuse 6 is a thermally responsive member.

Bimetal II - Temperature switch used, 11 & sex body?
I-There are many different temperature switches available.

According to the present invention, when the temperature of the fixing roller becomes high due to the occurrence of an abnormal situation, the fixing roller is arranged and fixed in the direction of thermal expansion by making the fixing roller thermally expand. By bringing the temperature fuse closer to the fixing roller, the temperature fuse quickly responds to the excessive heat generation of the fixing roller and melts, thereby quickly resolving the abnormal state.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the heating device of the present invention, Fig. 2 is an enlarged longitudinal sectional view of a part of 7, Fig. 6 is a block diagram of the heating circuit, and Fig.
The figure is an explanatory diagram of thermal expansion of the fixing roller. Fig. 5 is a graph of the heating time of the fixing roller versus the external temperature.
Fig. 6 is a vertical cross-sectional view of a fixing roller in which conventional bearings are adopted for structural reasons; Fig. 7 is a diagram showing an example of the bearing MIj of a μ foot landing roller; Fig. 8 is a longitudinal cross-sectional view of a fixing roller in which a conventional bearing is used due to its structure; The same figure showing the state and FIG. 9 show another example of the structure of the rotary roller bearing. 1 is the fixing roller, 2 & 2b are the bearings, and 6 is the electrode. 4 is a heater, 5 is a thermistor, and 6 is a temperature fuse. 7b frame body. Patent applicant: Canon Co., Ltd. Figure 8 Figure 7 Rn5? C) 1 27a

Claims (1)

[Scope of Claims] An ill heating source, and a heating element that is heated by the heat from the heating source and that is fixed so that the direction of thermal expansion changes greatly in a predetermined direction. and coupled between the heating source and a power source. It is arranged on one side of the heating element having a larger coefficient of thermal expansion change. A thermally responsive member a and t that change in response to heat from the glare source ρλ, etc.
I have it. If the heating source overheats, cut off the power supply from the power source p to the heating source due to the thermal change of the thermally responsive material. A heating device featuring: