JPS60257476A - Drum supporting device - Google Patents

Abstract

PURPOSE:To simplify the working process and to improve the precision by fitting the outside peripheral surface of an image forming drum and the inside peripheral surface provided on a flange to each other. CONSTITUTION:A ground inside peripheral surface 14 of a flange 13 is fitted to a ground outside peripheral surface 12 of a drum 11, and a shaft 1 is fitted and fixed to a center hole 15 of the flange. An inside peripheral surface 16 is an extrusion molding surface as it is, and the precision is not required. Since the main factor of factors causing deflection of the outside peripheral surface of the drum is deflection of the inside peripheral surface 14 of the flange 13 from the center hole 15 of the flange 13, deflection of the outside peripheral surface of the drum 11 is small.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support device for an image forming drum for electrophotography, thermal transfer, inkjet, etc.

More particularly, the present invention relates to a hanging drum support device which is preferably used for the imaging drum of an electrophotographic color printer.

A conventional device of this type will be explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing the structure of a conventional general electrophotographic photosensitive drum. The shaft l is rotatably supported by a bearing (not shown), and is rotationally driven by a gear wheel integrally fixed on the shaft l. The drum 3 is fitted into and fixed to a franchisor fixed to the shaft, and is supported so as to rotate integrally with the shaft.

Now, in this conventional example, as shown in FIG. 2, the drum 3 and the franchisor are manufactured as follows. First drum 3
is an aluminum extrusion material with an inner diameter of A and an outer diameter of B+α (α is the machining allowance). However, since the aluminum extrusion material does not meet the required accuracy, it is necessary to
is machined to an inner diameter C using a lathe, and the outer peripheral surface 7 is further machined to an outer diameter B using a lathe. Since the roughness of the turned surface is insufficient for coating the photosensitive layer on the outer diameter B, the mirror surface is further turned or polished at a high speed using a diamond tool.

Talented. The flange has a hole that fits into the shaft with an inner diameter of D and the fitting part of the drum 3! The outer circumferential surface 6 of the flange l" that fits with the flange l" is turned to an outer diameter E.

Now, Francita and Drum 3 were made in this way.
When only the eccentricity error is considered,
At the flange l in FIG. 1, an eccentric error of the outer circumferential surface B to which the shaft L is fitted with respect to the inner diameter of the flange L, and an eccentric error of the outer circumferential surface 7 relative to the fitting part 3 of the drum 3 are added.
These eccentric errors are more likely to occur as the diameter becomes larger due to processing, and are the dominant factor causing the drum 3 to run out. In addition to other errors such as roundness errors and cylindricity errors, the surface of the drum 3 generally has a surface runout of o, /! ; There is about tm. This drum 3 is applied to, for example, a laser beam printer, and a line parallel to the axis of the drum 3 is written as shown in FIG. When the written image is transferred to the transfer paper after development, the drum 3 is rotated periodically by one rotation of the drum 3 as shown in FIG.
Draw a fan shape from the area with the smallest surface runout to the area with the largest amount of runout. Although this amount is not much of a problem for general printers, it becomes a problem for printers that require particularly high precision or color printers.

Particularly in color printers, the fan-shaped changes occur randomly and independently for each color, resulting in color misregistration. In color printers, color shifts appear as hue shifts, so the human eye detects color shifts much more sensitively than in monochrome printers.

However, the above-mentioned conventional techniques have the disadvantage that they cannot meet the accuracy required for color printers. ′ fl'G , another conventional example is shown in the figure.

The shaft and gears are rotatably supported as in FIG. The flange is turned as shown in Figure 1,
The drum drum is manufactured by deep drawing, has a bearing portion formed at one end, and is supported by a bearing 10. In this example, the deflection of the outer circumference of the left end drum with respect to the bearing 10 is relatively good, but the deflection of the outer circumferential surface of the drum near the right flange, the outer circumferential surface of the drum near the right flange in the figure, is θ,
/krtas, and the color shift on the image was 0.3IaI.

The present invention provides a drum support device with simple processing steps and high precision.
It is an object of the present invention to provide a drum support device that can be particularly suitably used for color printers.

The present invention provides an image forming drum support device for an image forming apparatus in which the outer circumferential surface of the image forming drum and the inner circumferential surface provided on the flange are fitted together.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is a longitudinal cross-sectional view showing an embodiment of the present invention that is an improved version of FIG. The inner circumferential surface /4' turned into the flange /3 is fitted onto the polished outer circumferential surface 12 of the drive shaft /, / /, and the shaft l is fitted and fixed into the center hole 15 of the flange. According to this embodiment, the inner circumferential surface 16 of the drum // may be an extruded surface, and precision is not required. The reason why the outer periphery of the drum // fluctuates is the center hole 13 of the flange /3.
Since the deflection of the inner circumferential surface llI of the flange 13 is the main one, the deflection of the outer circumferential surface of the drum // is small.

FIG. 7 is a longitudinal sectional view of another embodiment of the present invention, which is an improvement on FIG. The drum 7 is formed by deep drawing as shown in FIG. 5, and the left shaft bearing part 17 is integrally formed. Since deep drawing has a relatively good surface roughness, it is not necessary to turn the bearing part 17 and the outer peripheral surface of the drum /g, but simply pay attention to the eccentricity between the center hole /S of the flange 13 and the inner peripheral surface /lI. All you have to do is pay
The manufacturing process is dramatically simplified. .

In another embodiment of the invention shown in FIG. 7, the flange /? The deflection of the outer circumferential surface of the drum near /1 is 0ρ3fl,
The color shift on the image is set to the target value of 0. / The fight has fallen short.

The reason why the accuracy is improved in the embodiments of the present invention shown in FIGS. 6 and 7 is that, for example, the eccentricity between the inner circumferential surface and the outer circumferential surface of the drum is independent of the runout of the drum disk, and as described above, assembly errors are caused. For example, the number of overlapping stages has decreased.

FIG. g shows an embodiment of a color printer to which the present invention is applied. This embodiment is a color printer made up of three sets of laser printers arranged side by side.

Laser light generated from the laser scanning system IT creates a latent image on the surface of the photosensitive drum SO, and the latent image becomes a visible image by the well-known Carlson process. Belt λ/ is a paper conveyor, made of polyester mesh or polyester film, and pulley 2λ9.23 tension pulley, 2
It is attached to the network. The transfer paper is conveyed in the direction of the arrow 2S, passes over transfer@denki and 2o in order so that the phase matches, and a full color image is transferred.

When the photosensitive drum SO of the type shown in Fig. S is used in this example described above, the color shift is θ, ? When using the photosensitive drum 20 using the drum support device of the type shown in FIG. 7 of the present invention, the target color misregistration value is 0. / I was able to supervise my subordinates.

Although the first embodiment of the present invention takes an electrophotographic apparatus as an example, the present invention can also be applied to other image forming apparatuses such as inkjet printers, thermal transfer printers, etc.

As explained above, the present invention has a structure in which the outer circumferential surface of the image forming drum of the image forming apparatus and the inner circumferential surface of the flange are fitted together, so that the fluctuation of the drum surface can be avoided for images required for color printers. Transfer accuracy can be ensured.

Drano of this example constructed using aluminum extrusion material, t
In this case as well, the process was simplified, but in other embodiments using deep drawn aluminum material, the process was further simplified and costs were significantly reduced.

[Brief explanation of drawings]

Figure m1 and Figure 2 are vertical cross-sectional views of conventional photosensitive drums, Figure 3 is
The figure shows the emitted light beam of a laser printer, FIG. 9 shows the image transferred to the transfer paper, the left figure shows a vertical cross-sectional view of another conventional photosensitive drum, and FIG. 6 corresponds to FIG. 1. FIG. 7 is a longitudinal sectional view of an embodiment of the present invention, FIG. 7 is a longitudinal sectional view of another embodiment of the invention corresponding to FIG. 3, and FIG. FIG. 3 is a side view of the embodiment. /, to--axis 3. q, //”・drum da, /J・・
Flange 6,7. /ko, /g-轡outer peripheral surface /lI. /6... Inner peripheral surface lS... Center hole 2o... Sensation ``Light drum. Figure 1 Figure 3 'W44 Figure 5

Claims (1)

[Claims] t. In a device that supports the image forming drum of an image forming apparatus on a shaft, an inner peripheral fitting part is provided on a flange fixed to the shaft supporting the image forming drum, and the fitting part is attached to the outer periphery of the image forming drum. A drum support device that is fitted together.