JPS6246857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying apparatus of a type in which a sheet-like photoreceptor is removably stretched over a rotating drum.

In this type of copying apparatus, when the same photoreceptor has been used to copy a predetermined number of sheets, that photoreceptor is replaced with a new photoreceptor. This work of replacing the photoreceptor is normally carried out by the user of the copying machine from outside the copying machine, and for this purpose it is necessary to be able to manually rotate the rotary drum to a desired position. Normally, the rotational motion of the rotating drum is synchronized with the movement of the optical system of a copying machine, and to ensure this synchronization, the same drive source as the optical system is used to drive the rotation of the rotating drum. The drum and its drive shaft are integrally connected. For this reason, replacing the photoreceptor requires an extremely large amount of time and effort, and the down time of the copying machine becomes longer, resulting in a decrease in office efficiency.

In the present invention, the rotary drum and its drive shaft are coupled via a cam so that the rotary drum can freely rotate relative to the drive shaft. Specifically, a drum having a photoreceptor on its outer peripheral surface is provided so as to be able to rotate independently with respect to a rotational drive shaft of the drum, and one end surface of the rotating drum is rotatable within a plane parallel to the end surface. A swing lever is provided, a pin is implanted at the end opposite to the pivot end of the swing lever, a cam plate is fixed to the drive shaft, and the pin of the swing lever is pressed against a part of the cam plate. The swing lever is urged in one direction by a spring, and the rotation of the drive shaft in one direction is caused to engage the pin with a part of the cam plate, thereby transmitting the rotation of the drive shaft to the drum. It is configured to encourage As a result, when replacing the photoreceptor, the rotating drum can be rotated at will to a position convenient for the user, so the time and labor required for replacing the photoreceptor can be reduced. However, in the present invention, since a cam connection is adopted between the rotating drum and the drive shaft, the unbalance of the rotating drum is caused by the weight distribution or the inertia during rotation. Preliminary rotation of the rotating drum tends to occur during manual rotation during photoconductor replacement work. In consideration of this point, the present invention employs a clutch mechanism to prevent the rotating drum from rotating in advance. A specific configuration of the clutch mechanism includes forming an extension portion extending in the axial direction through the drive shaft on one end surface of the rotating drum on which the swing lever is provided or on the opposite end surface thereof;
A sleeve is loosely fitted on the outside of the extension, one end of the sleeve is engaged with respect to the drive shaft, the other end is engaged with the extension, and when the drive shaft rotates in the drive direction, the drive shaft is rotated. It has been proposed that a spring tightened so as to be integrated with the extension part is loosely fitted across the extension part and the drive shaft. The spring is wound in the same direction as the rotation direction of the drive shaft (clockwise in the clutch mechanism according to the invention), and when the drive shaft rotates clockwise, the spring relaxes and the drum will therefore rotate clockwise. When this is done, the spring is tightened and the sleeve and drum are integrated.

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a mechanism of an electrophotographic copying apparatus with a movable document table using a rotating drum. In the figure, a document (not shown) placed on a moving document table 1 is irradiated by an irradiation lamp 2 as the document table 1 moves, and the reflected light from the document passes through a reflecting mirror 3 and a lens 4 to a rotating drum. The image is projected onto a sheet-like photoreceptor 6 stretched over the photoreceptor 5 . The photoreceptor 6 is uniformly charged in advance by a charging electrode 7, and when reflected light from the original is projected onto the photoreceptor 6, an electrostatic latent image of the original is formed. The electrostatic latent image is developed by a developing device 8 and converted into a visible image (toner image), which is transferred by a transfer pole 12 from a paper feed tray 9 to a transfer paper fed by a feed roller 10 and a paper feed roller 11. . The transfer paper carrying the toner image is separated from the rotating drum 5, conveyed by a conveying device 13 to a fixing device 14, where it is fixed, and is discharged onto a paper discharge tray 15 as a copy.

In the copying apparatus having the mechanism shown in FIG. 1, both edges of the sheet-like photoreceptor 6 are stretched and fixed to the outer circumferential surface of the rotating drum 5 by means of a mounting plate 16, and there are various known tensioning and fixing mechanisms. Furthermore, since this is not the gist of the present invention, its explanation will be omitted. Normally, the photoreceptor replacement work is carried out manually by the user after opening the copying machine top cover 17 provided substantially above the rotating drum and rotating the rotating drum to a desired position.

2 to 4 show the drive mechanism of the rotating drum according to the present invention in detail. First, referring to FIG. It is rotatably supported by bearings 21 and 22 attached to a frame 20. The rotating drum 5 is rotationally driven by a gear 23 fixed to the tip of one rotating shaft 5a via a known drive mechanism (not shown). A sheet-like photoreceptor 6 is stretched and fixed on the outer peripheral surface of the rotating drum 5 by a known mounting plate 16 .

Next, referring to FIG. 3, a lever 2 is mounted on one end surface of the rotating drum 5 and is swingable about a shaft 24.
5, and a pin 26 is implanted at the end of the lever 25 opposite to the center of swing. On the other hand, a cam plate 27 is fixed to the rotating shaft 5a of the rotating drum 5. The cam plate 27 has a substantially circular shape and engages with the pin at a cam surface formed on a part of the outer peripheral surface. Furthermore, a pin 28 is implanted at a position close to the periphery of the end surface of the rotating drum 5, and one end of a wire spring 29 wound around the shaft 24 is connected to the pin 28.
8, bend the other end at right angle, and attach the lever 25.
By locking the pin 26 of the lever 25 against the upper edge of the cam plate 27, the pin 26 of the lever 25 is constantly pressed against the side edge of the cam plate 27 including the cam surface 27a.

Referring again to FIG. 2 together with FIG. 4, a hub 30 is fixed to the other end surface of the rotating drum 5.
A sleeve 31 having an enlarged head at one end is loosely fitted onto the outer periphery of the rising portion 30a of the hub 30. Inside this sleeve 31, another sleeve 32 is fixed to the rotating shaft 5b and has an enlarged head at one end.
is still loosely fitted. Both sleeves 31, 32
A spring 33 is loosely placed between them.
As can be clearly seen in FIG. 4, teeth 31a are formed on the outer periphery of the enlarged head of the sleeve 31, and a slot 31b is formed at the other end, and one end of the spring 33 is bent and engaged. on the other hand,
A slot 32a is formed at the other end of the sleeve 32, and the other end of the spring 33 is bent and engaged with the slot 32a.

Now, to explain the operation of the drive mechanism of the present invention with reference to FIGS. 2 to 4, the rotating shaft 5a is now rotated by the drive mechanism (not shown) via the gear 23, and as a result, the cam plate 27 is rotated as shown in FIG. When the pin 26 of the lever 25 is rotated in the direction of the arrow shown in
If the cam plate 27 is engaged with the cam surface 27a of
The rotation is transmitted to the rotating drum 5 via the pin 26, and the rotating drum 5 itself is also rotated in the same direction. The pin 26 of the lever 25 is connected to the cam surface 27a of the cam plate 27.
When the spring 33 is not engaged with the rotating drum 5, the spring 33 disposed at the other end of the rotating drum 5 is loosened, and the rotation of the drive shaft 5b is not transmitted to the rotating drum 5. Only 27 rotates, and when it comes to the engagement position, it engages with the pin 26 and rotates the rotating drum 5.

The rotating drum 5 may rotate ahead of the rotation of the cam plate 27 due to structural imbalance of the drum 5 during rotation, or may attempt to continue rotating due to inertia when the rotating shaft 5a stops. When the spring 33 is tightened, the sleeve 32 and the hub 30 are integrated by the spring 33, and as a result, the rotating drum 5 is prevented from rotating in advance relative to the cam plate 27. In this way, the spring 33 is disposed between the rotating drum and its drive shaft, and is tightened to prevent movement of the rotating drum in one direction with respect to the drive shaft, thereby unifying the two, and prevents movement in the opposite direction. The spring 33 functions as a clutch mechanism that relaxes the two to allow free movement between the two, and a spring 33 that functions in this manner is called a spring clutch. In the present invention, it is of course possible to use not only springs but also other members having the above-mentioned functions.

[Brief explanation of the drawing]

FIG. 1 of the accompanying drawings is a schematic diagram of the copying mechanism of an electrophotographic copying device with a movable document table, FIG. 2 is an enlarged partial cross-sectional view of the rotary drum drive mechanism and clutch mechanism used in the copying device, and FIG. A reduced end view of one side of the rotating drum taken along the line A-A in Fig. 2, No. 4
The figure is a reduced end view of the other rotary drum taken along line BB in FIG. 2. 1...Original table, 2...Irradiation lamp, 3...Reflector, 4
... Lens, 5... Rotating drum, 5a, 5b... Rotating shaft, 6... Sheet-like photoreceptor, 7... Charging electrode, 8... Phenomena device, 9... Paper feeding plate, 10... Feeding roller, 11
...Paper feed roller, 12...Transfer pole, 13...Transport device,
14... Fixing device, 15... Paper discharge tray, 16... Mounting plate,
17... Lid, 20... Frame, 21, 22... Bearing, 23
...Gear, 24...Shaft, 25...Lever, 26, 28...
Pin, 27...Cam plate, 27a...Cam surface, 29...Wire spring, 30...Hub, 30a...Rising portion, 31, 32...Sleeve, 31a...Teeth, 31
b, 32a...Slot, 33...Spring.

Claims (1)

[Scope of Claims] 1. A drum having a photoreceptor on its outer peripheral surface is provided so as to be able to rotate independently with respect to a rotational drive shaft of the drum, and a drum is provided on one end surface of the rotating drum to rotate in a plane parallel to the end surface. A movable rocking lever is provided, a pin is implanted at the end opposite to the pivot end of the rocking lever, and a cam plate is fixed to the drive shaft, and the pin of the rocking lever is connected to the cam plate. The swing lever is biased in one direction by a spring so as to be in pressure contact with a portion thereof, and the rotation of the drive shaft causes the pin and the cam plate to engage, thereby transmitting the rotation of the drive shaft to the drum. In a rotary drum drive mechanism of an electrophotographic copying device, an extension portion extending in an axial direction is formed on an end surface of the rotary drum so that the drive shaft passes through the rotary drum;
A sleeve is loosely fitted on the outside of the extension, one end is engaged with a part of the sleeve, the other end is engaged with the drive shaft, and when the drive shaft rotates in the drive direction, the drive shaft is rotated. A rotating drum for an electrophotographic copying apparatus, characterized in that a helical spring tightened so as to be integrated with the extension is loosely fitted across the extension and a drive shaft. 2. The rotating drum drive mechanism according to claim 1, wherein the extension portion is formed on one end surface of the rotating drum, and the swing lever is provided on the other end surface.