JP2550345Y2 - Fixing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly, to a fixing device incorporated in an image forming apparatus such as a copying machine or a facsimile for fixing a toner image transferred to an image forming sheet.

[0002]

2. Description of the Related Art Conventionally, as a fixing device incorporated in an image forming apparatus, a fixing heating roller having a built-in heating heater, which is rotatably arranged, and an endless arrangement which is brought into contact with the heating roller are arranged. And a fixing belt that rotates together with a heating roller and fixes the toner image transferred onto the surface of the image forming paper.

In such a fixing device, a heating roller is heated by a heating heater, so that a fixing portion including a heating roller and a fixing belt is heated to a fixed temperature (120 to 1).
30 ° C.).

[0004]

In such a fixing device, the fixing belt keeps the above-mentioned constant temperature at the portion in contact with the heating roller, but the portion not in contact with the heating roller, especially the fixing belt, The temperature opposite to the heating roller is lower than the above-mentioned constant temperature. For this reason, the time from when the main switch of the image forming apparatus is turned on until image formation such as copying becomes possible (stable time) or the time when image formation is started after the stable time elapses (standby time) There was a problem that it became long.

The present invention has been made in view of the above circumstances, and has as its object to provide a fixing device capable of maintaining a fixing unit in a standby state at an appropriate temperature and reducing a stabilization time and a standby time. I do.

[0006]

According to the present invention, there is provided a fixing heating roller which is rotatably disposed and has a built-in heater for heating, and a fixing heating roller which is brought into contact with the heating roller and has a function.
A fixing belt that is supported by a pair of belt rollers and arranged in an endless manner, rotates together with the heating roller, and fixes the toner image transferred to the surface of the image forming paper;
Further, the fixing belt is provided at a position opposite to the heating roller via the fixing belt and the belt roller, and the back surface of the fixing belt is provided.
Is a fixing device provided with a belt heater that heats the fixing belt by directly or indirectly contacting the surface of the fixing belt in a region away from the belt roller .

That is, the fixing device of the present invention is characterized in that a belt heater is provided at a position opposite to a heating roller via a fixing belt and a belt roller . In this belt heater, the back surface of the fixing belt is
The fixing belt is heated by being brought into contact with the surface of the fixing belt in the separated area . Then, the temperature of the fixing unit is effectively prevented from lowering, and the temperature is kept in an appropriate range.

Here, for example, a linear heater or a planar heater is used as the belt heater. The belt heater may be directly in contact with the fixing belt, but is more preferably in contact with the fixing belt via a specific member in order to reduce the load on the fixing belt.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited by the following embodiments.

In FIG. 1, a fixing device P mounted in a main body of a copying machine as an image forming apparatus is rotatably disposed and has a power consumption of 1000 W comprising a straight tube type halogen lamp.
A fixing heating roller 2 having a built-in heating heater 1 therein;
A fixing belt 3 is provided below the heating roller 2 so as to be in contact with the heating roller 2 and arranged endlessly. The fixing belt 3 is rotated by the two belt rollers 4 and 4 together with the heating roller 2 in the direction of the arrow, and the toner transferred to the surface of the copy sheet while conveying the copy sheet as the image forming sheet from left to right. Fix the image.

In FIG. 1, reference numeral 5 denotes a cover disposed above the heating roller 2. Reference numeral 6 denotes a cleaning roller, which contacts the heating roller 2 to clean the heating roller 2. Reference numeral 7 denotes a paper guide disposed to the right of the heating roller 2, and guides the copy paper on which fixing has been completed to the outside of the fixing device P. Reference numeral 8 denotes an oil application roller that is brought into contact with the fixing belt 3 below the two belt rollers 4. The oil application roller 8 applies oil to the fixing belt 3 so that toner does not adhere to the fixing belt 3. Reference numeral 9 denotes a fixing thermistor arranged to the left of the heating roller 2, which detects the temperature of the fixing roller 2 and keeps the temperature of the fixing unit at 120 to 130 ° C.

The fixing device P further includes a fixing belt 3
Power consumption 140 at a location opposite to the heating roller 2 through the
A belt heater 10 of W is provided. That is, as shown in FIGS. 2 and 3,
An aluminum tape 12 is attached to a flat rectangular leaf spring 11 made of a thin steel plate and brought into contact with the surface of the fixing belt 3.
Is a linear ceramic heater attached in a U-shape. The leaf spring 11 and the belt heater 10 are arranged over substantially the entire width of the fixing belt 3 at the center of the surface of the fixing belt 3 opposite to the heating roller 2.
Here, the leaf spring 11 is attached to the bottom wall 13 of the fixing device P by a screw 1.
The urging force acts in the clockwise direction to bring the belt heater 10 into contact with the fixing belt 3 via the leaf spring 11.

Next, FIG. 4 shows the relationship between the temperature of the heating roller 2 and the time when fixing is performed using the fixing device P. That is, first, the main switch of the copying machine is turned on while the heating roller 2 and the fixing belt 3 are stopped. Then, the heating heater 1 and the belt heater 10 of the heating roller 2 are turned on, and the temperature of the heating roller 2 increases with the passage of time. The temperature of the heating roller 2 is 100 ° C.
(Time t ₁ ), the heating roller 2 and the fixing belt 3 start rotating. At this time, since the heat of the heating roller 2 is taken by the fixing belt 3, the temperature of the heating roller 2 decreases with time. Thereafter, since the fixing belt 3 is also heated to some extent by the belt heater 10 and the heating roller 2, the temperature of the heating roller 2 rises again.

When the temperature of the heating roller 2 reaches 130 ° C. (at time t ₂ ), the main body of the copying machine is driven primary, and the rotation speeds of the heating roller 2 and the fixing belt 3 increase. For this reason, the temperature rise in the heating roller 2 within a predetermined time is gradual, but thereafter rises sharply. Then, the temperature reaches 140 ° C., which is the feasible temperature (at time t ₃ ), and the copying machine is ready for copying.

In FIG. 4, the time from the turning on of the main switch of the copying machine to t3, that is, the stabilization time was 10 minutes and 30 seconds. On the other hand, when the stabilization time of the conventional fixing device without the belt heater 10 of the fixing device P was measured under the same conditions, it was 12 minutes and 10 seconds.

In the fixing device P, the fixing belt 3
A belt heater 10 is provided at a position opposite to the heating roller 2 via the belt rollers 4, 4.
The fixing belt 3 can be heated by being brought into contact with the surface of the fixing belt 3 in a region away from the fixing belt 4 . As a result, the temperature on the opposite side to the heating roller 2 via the fixing belt 3 and the belt rollers 4- the temperature of the fixing belt 3 becomes the highest.
It is possible to effectively prevent the temperature from being lowered at the place where the temperature may be lowered. Therefore, according to the copier incorporating the fixing device P, the stabilization time can be shortened by 1 minute and 40 seconds (12 minutes 10 seconds-10 minutes 30 seconds) as compared with the conventional example. The same can be said for the standby time.

[0017]

Advantages of the Invention Since the fixing device of the present invention is configured as described above, when the fixing device is incorporated in an image forming apparatus and used, the temperature of the fixing unit in a standby state is most lowered.
A certain portion is heated by a belt heater to keep the portion at an appropriate temperature, and the stabilization time and the standby time can be shortened as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of a fixing device according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part configuration as viewed from a side of the fixing device.

FIG. 3 is an explanatory diagram of a main part configuration viewed from a lower surface of the fixing device.

FIG. 4 is a diagram showing the relationship between the temperature of a heating roller and time when fixing is performed using the fixing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 heating heater 2 heating roller 3 fixing belt 4 belt roller 10 belt heater 11 leaf spring

Claims (1)

(57) [Scope of request for utility model registration] 1. A fixing heating roller rotatably arranged and having a built-in heating heater, and an endless heating roller abutted on the heating roller and supported by a pair of belt rollers. rotates together with, and a fixing belt for fixing the toner image transferred onto the surface of the image forming sheet, further, provided at a location opposite to the heating roller via the fixing belt and the belt roller, a fixing belt Back of
A fixing device including a belt heater for heating the fixing belt by directly or indirectly contacting the surface of the fixing belt in a region away from the belt roller .