JPS6227781A - Heat roller fixing device - Google Patents

Abstract

PURPOSE:To make the surface temperature of a heat roller approximately constant without making the whole of a device large-sized to prevent creases of recording paper by press-fitting an inner cylinder into an outer cylinder of the heat roll which is in contact with the recording paper and forming a space in the center in the axial direction between outer and inner cylinders. CONSTITUTION:Though the heat radiated from a heat source 2 like a halogen lamp is transmitted from the inside wall of a heat roll 1' toward the surface, heat is migrated from an inner cylinder 1b to an outer cylinder 1a in both end parts of the heat roll 1' by conduction heat transfer due to contacting between both cylinders, and the thermal resistance is increased in the center by radiation heat transfer of a space 1c, and the temperature fall in the center is greater than that in both end parts. The extent of tapering of a recessed part of the inner cylinder 1b is set to compensate the fact that the surface temperature is high in the center and is low in both end parts when the recessed part is not provided to make the thickness uniform, thereby keeping the surface temperature distribution approximately constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heating roller fixing device for information recording equipment such as facsimile machines, copying machines, and printers.

[Prior Art] A heating roller fixing device in a conventional information recording apparatus will be described with reference to FIGS. 2 to 4.

FIG. 2 is a schematic side view of a heating roller fixing device in a general information recording device. Toner 4 is adhered to the recording paper 3 by a recording device and a developing device (not shown) in a pre-fixing stage at positions corresponding to characters, etc. of the document read by the reading device.

However, the adsorption force of this toner 4 to the recording paper 3 is very weak, and in order to obtain a stable recorded image, it is necessary to fix the toner using heat, pressure, or the like.

A heat source 2 such as a halogen lamp is inserted inside the heating roller 1, and the heating roller 1 is heated by the heat source 2. Reference numeral 5 denotes a pressure roller for pressing the recording paper 3 against the heating roller 1, and the recording paper 3 is pressed against the arrow C by the rotation of the heating roller l in the direction of arrow A and the rotation of the pressure roller 5 in the direction of arrow B. conveyed in the direction. The recording paper 3 comes into contact with the heating roller 1 while being conveyed, and the toner 4 adhering to the heat roller 1 is fused to the recording paper 3 by the heat of the heating roller 1.

By the way, in this way, heat is used to transfer toner 4 to recording paper 3.
In a heating roller fixing device for fixing images, a temperature sensing element 6 is provided to detect the surface temperature of the heating roller 1 in order to always maintain the surface temperature of the heating roller 1 at a predetermined fixing temperature. The operation of the heat source 2, such as the halogen lamp, is controlled via the control mechanism, thereby keeping the surface temperature of the heating roller 1 constant.

However, in the halogen lamp, the filament coil is arranged along the axis of the heating roller l, but if the entire filament is a uniform heat generating part, the temperature distribution in the length direction of the heating roller l is As shown in FIG. 3, since the heat dissipation is large at both end portions, the center portion is higher than both end portions, and as a result, the heating roller 1 cannot obtain a uniform heating effect over its entire length, and the recording paper In order for the above toner to be completely fused over the entire screen, a sufficient fusion temperature must be maintained at both ends where the temperature is lower, and the temperature in the center becomes higher than necessary, resulting in The occurrence of wrinkles is observed due to local differences in the degree of shrinkage of the recording paper 3 due to evaporation of moisture.

In order to avoid such drawbacks of the conventional method, the length of the heating roller l and the heat source 2 such as a halogen lamp should be made sufficiently longer than the width of the recording paper 3, and a central part where the heat distribution is relatively flat should be used. or filament 2 of heat source 2 such as a halogen lamp.
There is a method of keeping the temperature on the surface of the heating roller 1 substantially constant by making the coil density sparse at the center and dense at both ends to provide heat generation characteristics as shown in FIG.

[Problems to be Solved] In the conventional heat roller fixing device described above, the length of the heating roller l must be sufficiently long compared to the width of the recording paper 3, which increases the size of the entire device and increases the density of the heater coil. There are manufacturing difficulties in changing the lamp, and since both end portions are heated to a high temperature, the 8#i2 insulator of a halogen lamp or the like is adversely affected by the high heat, resulting in a shortened lifespan.

[Means for Solving Problems] The present invention was made to solve the above-mentioned conventional problems, and it is possible to keep the roller surface temperature approximately constant and prevent wrinkles on recording paper without increasing the size of the entire device. The aim is to provide something more reliable.

To this end, the present invention provides a rotating heating roller having a heating element inside, and a rotating heating roller (15
In a heating roller fixing device equipped with a pressure roller attached to The present invention provides a heating roller fixing device characterized by having a gap formed therein.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention.

The heating roller 1' is integrated by press-fitting an inner cylinder 1b having a tapered concave shape at the center in the axial direction of the outer diameter into an outer cylinder 1a. Thus, a void 1c is formed.

Heat radiated from a heat source 2 such as a halogen lamp is conducted from the inner diameter wall of the heating roller 1' toward the surface, but at both ends of the heating roller 1', the inner cylinder 1b is connected to the outer cylinder 1a in a 100-cylindrical manner. Heat is transferred by conductive heat transfer due to contact, but the thermal resistance is thicker in the center due to radiant heat transfer in the void 1c, and the temperature drop in the center is larger than at both ends.

Therefore, the taper amount of the concave portion of the inner cylinder 1b at this time is
By setting to compensate for the fact that when there is no concave part and the wall thickness is constant, the surface temperature distribution is high at the center and low at both ends.

The surface temperature distribution can be kept approximately constant.

In addition, in the embodiment, a tapered concave shape was formed on the outer diameter of the inner cylinder 1b from the viewpoint of ease of processing, but even if this tapered concave shape is formed on the inner diameter of the outer cylinder 1a, the inner diameter of the outer cylinder and the inner cylinder 1b It may be formed on both outer diameters.

[Effects of the Invention] As described above, according to the present invention, a heating roller fixing device including a rotating heating roller having a heating element inside and a pressure roller attached to the rotating rotation while pressing the heating roller. The heating roller fixing device is characterized in that an inner cylinder is press-fitted into the outer cylinder of the heating roller that comes into contact with the recording paper, and a gap is formed in the axial center between the outer inner cylinder and the inner cylinder. The reliability of wrinkle prevention can be improved by obtaining a heating roller having a gap in the central thick part, thereby making the surface temperature distribution path constant.

Further, there is an effect that the reliability of preventing wrinkles can be improved without significantly increasing the amount of heat generated at both ends of the halogen lamp within the heating roller, in other words, without shortening the life of the halogen lamp.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. FIG. 2 is a schematic side view of a conventional heating roller fixing device. FIG. 3 is a diagram showing the temperature distribution on the surface of a conventional heating roller. FIG. 4 is a diagram showing the heat generation distribution of a conventional heater. 1': Heating roller 1a: Outer cylinder ■b: Inner cylinder IC=void 2: Heat source 3: Recording paper 5: Pressure roller

Claims (1)

[Claims] In a heating roller fixing device that includes a rotating heating roller having a heating element inside and a pressure roller rotatably attached to the heating roller while being pressed against the heating roller, an inner cylinder is placed inside the outer cylinder of the heating roller that comes into contact with the recording paper. A heating roller fixing device characterized in that the heating roller fixing device is press-fitted and a gap is formed in the center in the axial direction between an outer cylinder and an inner cylinder.