JPS6246194Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a brake device for eliminating speed unevenness of a photosensitive drum rotatably mounted within the body of an electronic copying machine.

In recent years, a wide variety of electronic copying machines have been put into practical use. Among these, transfer-type electronic copying machines are the most commonly used. As is well known, this process involves exposing a photosensitive drum containing a photosensitive material from a table on which an object such as a manuscript is placed, attaching toner containing a carrier to the latent image area, transferring it to paper, and fixing it. , which completes the copying. However, in this copying process,
There must be no relative velocity unevenness between the moving speed of the table on which the subject is placed and the circumferential speed of the surface of the photoreceptor drum, and it is necessary to maintain a constant speed relationship. Similarly, there must be no speed unevenness between the circumferential speed and the moving speed of the paper to be transferred, and a one-to-one speed relationship must always be maintained.

Conventionally, as shown in FIG. 1, the rotation of the photosensitive drum 1 is controlled by a chain or timing belt 2 linked to the same drive source as the table, paper feed, etc., to a gear 3, an idle gear 4, and a gear on a driving gear shaft. 5 and the other gear 6 on the shaft, the signal is transmitted to the gear 7 concentrically fixed to the photosensitive drum 1.

However, the rotation resistance of the photoreceptor drum 1 changes due to the unbalance of the photoreceptor drum itself, the toner contact resistance of the nearby developing device, the magnetic resistance, the resistance of the paper feeding mechanism of the paper to be transferred, etc. The backlash of the chain and gears in the system causes microscopic speed changes, resulting in double images and a decrease in clarity of the copied image.

For this reason, the conventional speed adjustment method is
In order to eliminate as much looseness and bumpiness as possible in the chain, gears, keys, etc. of the drive system, efforts were made to improve the precision of each part, adjust the distance between gear axes, and equalize rotational resistance, but these adjustments were difficult. has
Another problem was that the cost was extremely high.

This idea was created in view of the above circumstances, and its purpose is to apply a brake to the rotation of the photoreceptor drum by pressing a friction member against it, and thereby to brake the entire drive system of the photoreceptor drum. , it is possible to remove backlash and obtain uniform rotation with no unevenness in speed even if there is a change in the rotational resistance of the photoreceptor drum, and it is possible to increase the clarity of the copied image and prevent double images, out-of-focus, etc. The object of the present invention is to provide an electronic copying machine that can reduce costs by eliminating the need for difficult adjustment operations and by simplifying the configuration.

An embodiment of this invention will be described below with reference to FIGS. 2 to 4.

In the figure, 11 and 12 are frames on both sides provided inside the body of the electronic copying machine, and 13 and 14 are frames 1 on both sides.
Bearings fixed at opposite locations of 1 and 12, 1
Reference numeral 5 denotes a drive gear serving as a drive means which is rotatably attached to the bearing 13 on one side of the bearing 13 via a bush 16; 17 is a removable shaft; one end of this shaft 17 connects to the bearing 13 via the drive gear 15; In other words, it is fitted into the center of the drive gear 15 so as to rotate together with the drive gear 15, and the other end is supported by the bearing 14 so that it is rotatably suspended horizontally. holders 18 and 19 are fitted to the ends of the shaft 17 with spacers 20 in between, with a predetermined distance between them;
Reference numeral 21 denotes a photosensitive drum which is attached to rotate together with the shaft 17 via both holders 18 and 19.

Thus, the photosensitive drum 21 is rotated simultaneously with the shaft 17 by the rotation of the drive gear 15, which is linked to the drive source in the body of the copying machine via a chain, gears, etc., as in the conventional case. It's summery.

Both end walls 21 of the photosensitive drum 21 having such a structure
Flexible friction members 22, 22 made of rubber, sponge, etc. are press-fitted between the frame a, 21b and the frames 11, 12 arranged to face each other in the vicinity thereof. That is, in detail, the friction member 2
2 and 22 are fixedly attached to the frames 11 and 12, and at this time, the friction members 22 and 22 are elastically recessed in an L-shape at the corner of one side of the friction members 22 and 22, as shown in FIG. End wall 21 of the photosensitive drum 21
The peripheral edges of a and 21b are brought into pressure contact.

With this, the photoreceptor drum 21 has both end walls 21
Since a and 21b are rotated while being in moderate pressure contact with the friction members 22 and 22, uniform rotation without uneven speed can be obtained by the braking caused by the frictional resistance, which improves the clarity of the copied image and eliminates double images and out-of-focus images. can be prevented.

Note that this invention is not limited to the above-described embodiment; for example, as shown in FIG. However, this may extend over the entire circumference, or the position of pressure contact may be changed.

Further, as shown in FIG.
A friction member 26 such as a lever that rotates and presses against the surface may be used. Furthermore, as shown in FIG. 6, a separate disk 27 is attached to the end of the photoreceptor drum 21.
A friction member 28 such as a leaf spring may be pressed against the disk 27 to rotate integrally with the disk 27. In this case, wear and tear on the photosensitive drum 21 itself can be prevented.

As described in detail above, this invention can apply an appropriate brake to the rotation of the photoreceptor drum by pressing the friction member, so although it has an extremely simple structure, it eliminates all bumps and backlash in the photoreceptor drum drive system. Even if there is a change in the rotational resistance of the photoreceptor drum, uniform rotation without unevenness in speed can be obtained, the clarity of the copied image can be improved, double images and out-of-focus can be prevented, and the structure can be improved. To provide a photoreceptor drum brake device for an electronic copying machine that is simple and does not require troublesome adjustment operations, reduces costs, and is highly economical.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing a conventional example, Fig. 2 is a cross-sectional view showing an embodiment of the invention, Fig. 3 is a side view of the main part, and Fig. 4 is an enlarged sectional view of the main part. , 5th
6 and 6 are schematic perspective views showing other different embodiments of this invention. 21... Photosensitive drum, 22, 26, 28...
Friction member.

Claims (1)

[Scope of utility model registration request] In an electronic copying machine comprising a photoconductor drum rotatably mounted in the body of the electronic copying machine and a driving means for driving the photoconductor drum, an end portion of the photoconductor drum or a member separate from the photoconductor is provided. A photoreceptor drum brake device comprising a friction member that presses against a part of a rotating part that rotates integrally with the dowel to maintain uniform rotation of the photoreceptor.