JPS5933788A - High frequency induction heating roller - 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 Field of Industrial Application This invention relates to a high frequency induction heating roller such as a fixing roller for a copying machine.

Structure of a conventional example and its problems FIG. 1 shows a sectional view of a conventional high frequency induction heating roller A. This high-frequency induction heating roller A has an induction coil 2 concentrically arranged inside a cylindrical metal roller body 1 so that the induction coil 2 is evenly distributed, and a high-frequency current is applied to the induction coil 2. When the current is applied, the current distribution flowing through the roller body 1 is smaller at both ends than at the center, as shown by current distribution curve B in FIG. Furthermore, since heat radiation is greater at both ends than at the center, the difference in temperature distribution becomes larger than in current distribution, as shown by temperature distribution curve C in FIG. As described above, since the temperature difference of the roller body 1 becomes large between both ends and the center, there has been a problem of poor heating efficiency.

OBJECTS OF THE INVENTION An object of the present invention is to provide a high frequency induction heating roller that can substantially equalize the temperature distribution of the roller body and improve heating efficiency.

Structure of the Invention The high-frequency induction heating roller of the present invention has an induction coil wound spirally so that it is sparsely wound in the center and densely wound at both ends, and is concentrically arranged inside a cylindrical roller body. The magnetic flux density generated at both ends is increased, heat generation at both ends of the roller body is increased, and the temperature distribution of the roller body is made uniform.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 3 to 5. That is, this high frequency induction heating roller D
As shown in the figure, the entire induction coil 3 is wound spirally so that it is sparsely wound at the center and densely wound at both ends, and is arranged concentrically within the cylindrical metal roller body 4.

As a result of this configuration, when a high-frequency current is passed through the induction coil 3, the magnetic flux density at both ends of the coil is greater than that at the center of the coil. Therefore, the current distribution flowing inside the roller body 4 follows the current distribution curve E in FIG. As shown in , more current flows at both ends than at the center. Since the heat generation distribution of the roller body 40 is proportional to the current distribution flowing through the roller body 4, the heat generation distribution curve F in FIG. 5, which is proportional to the current distribution curve E in FIG. 4, is obtained as the heat generation distribution. On the other hand, the roller body 4
The heat dissipation distribution changes with time, but the heat dissipation is greater at both ends than at the center, resulting in a heat dissipation distribution curve G as shown in FIG. Therefore, the surface temperature distribution of the roller body 4 is obtained by subtracting the heat radiation distribution curve G from the heat generation distribution curve F, that is, the temperature distribution curve H that is almost uniform over the entire roller body as shown in FIG. is obtained. In this way, a substantially uniform temperature distribution can be obtained in the roller body 4, and as a result, heating efficiency can be improved.

Furthermore, since a fixing roller for a copying machine is particularly required to have a uniform surface temperature distribution of the roller body, the high frequency induction heating roller according to this embodiment is extremely valuable when used as a fixing roller for a copying machine. .

In the above embodiment, the induction coil 3 is formed in only one layer, but may be formed in two layers. That is, other induction coils (not shown) may be arranged concentrically inside the induction coil 3, which are evenly distributed and spirally wound.
In that case as well, the same effects as in the above embodiment can be achieved.

Effects of the Invention According to the high frequency induction heating roller of the present invention, it is possible to substantially equalize the temperature distribution of the roller body and improve the heating efficiency.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional example, Fig. 2 is a temperature distribution characteristic diagram of the roller body, Fig. 3 is a sectional view of an embodiment of the present invention, and Fig. 4 is a sectional view of a conventional example.
The figure is a current distribution characteristic diagram of the roller body, and FIG. 5 is a diagram of heat generation, heat radiation, and temperature distribution characteristics of the roller body. 3...Induction coil, 4...Roller body, D...High frequency induction heating roller Representative Patent Attorney Akio Ii (5) Figure 1 Figure 2

Claims (2)

[Claims] (1) A high-frequency induction heating roller that includes a cylindrical roller body and an induction coil that is spirally wound so that the center portion is sparse and both ends are densely wound and arranged concentrically within the roller body. (2) The high-frequency induction heating roller according to claim M(1), wherein the induction coil is provided with another induction coil concentrically wound evenly in a spiral shape.