GB1565539A - Advanceable photoreceptor - Google Patents

Description

(54) ADVANCEABLE PHOTORECEPTOR (71) We, XEROX CORPORATION, a corporation organised under the laws of the State of New York, United States of America, of Rochester, New York 14644, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to xerographic copying apparatus wherein electrostatic images are formed on the surface of an electrophotographic member with subsequent development of the latent images formed thereby and more particularly to an advanceable photoreceptor construction for use therein.

In the process of xerography the image of an original to be copied is recorded in the form of a latent electrostatic image upon an electrophotosensitive member with subsequent rendering of the latent image visible by the application of electroscopic marking particles, commonly referred to as toner. A latent image may also be formed on the electrophotosensitive member by exposmg a uniformly charged photosensitive member to an optical image corresponding to intelligence generated by electronic means.

In the earliest developments of the technology, the electrophotosensitive member was constructed in the form of a drum which was supported for rotation such that it could be uniformly charged electrostatically, with subsequent exposure, thereof to a light image in order to discharge portions of the electrophotosensitive member in accordance with the light image and then the image portion of the electrophotosensitive member was moved past a development station where the electrostatic image was rendered visible by the application of toner particles which electrostatically adhered to the electrophotosensitive member in the areas thereof still containing electrostatic charge.

Subsequent developments, in the electrophotosensitive member area, designed to improve the performance (i.e. less maintenance, etc.) of the reproducing apparatus led to the use of what has become known as an advanceable photoreceptor. The advanceable photoreceptor comprises a web of electrophotosensitive material the bulk of which is supported internally of a hollow drum while a portion thereof is trained over the outer surface of the drum for employment in the image forming process. The bulk of the web is supported internally of the drum by a supply roll containing unused electrophotosensitive material and a takeup roll which contains electrophotosensitive material which has already been used.In operation, the portion of electrophotosensitive material entrained on the surface of the drum is utilized until such time as the effectiveness thereof for such purposes begins to diminish or becomes unsuitable for such purposes. At that time, the transport mechanism comprising the takeup reel and supply reel is actuated either automatically or manually in order to move the used electrophotosensitive material onto the takeup reel and move unused electrophotosensitive material from the supply reel to the surface of the hollow drum.

Presently, electrophotosensitive webs of the type herein contemplated are advanced a complete section at a time, which advancement is accomplished by means of clutches, gears, logic controls, etc. which preclude the advancement of the photoreceptor during normal operation of the copier.

According to the present invention, we provide advanceable photoreceptor apparatus comprising a hollow drum having a slot substantially coextensive with the longitudinal axis of said drum, said drum being adapted for rotational movement, means for supporting a major portion of an electrophotosensitive web including both ends thereof internally of said drum while a smaller portion thereof is trained over the outer surface of said hollow drum, and means for automatically effecting regular incremental advance of said electrophotosensitive web round said drum during each revolution of said drum.

According to another aspect of the present invention we provide a method of advancing an electrophotosensitive web supported by a hollow drum having a major portion of said web including both ends thereof supported internally of said drum and a smaller portion supported on the surface thereof, said method including the steps of rotating said drum with said smaller web portion passing a plurality of xerographic processing stations, and effecting regular incremental advance of said electrophotosensitive web during each revolution of said drum.

In a preferred embodiment of the invention a xerographic reproducing apparatus is provided with an advanceable photoreceptor construction having a hollow drum in which the bulk of an elongated electrophotosensitive web is supported by supply roll and a takeup roll while a portion of the electrophotosensitive web is trained over the outer surface of the hollow drum for utilization in the electrostatic image forming process.

The takeup roll is adapted for automatically effecting incremental movement of the web each time the drum makes a complete revolution. To this end, a slip clutch and ratchet mechanism may form part of the takeup roll.

An actuator assembly pivotally mounted to the hollow drum may serve to incrementally move the slip clutch and ratchet mechanism each time the actuator is reciprocated by means of a cam which is stationarily mounted on the machine frame adjacent the photoreceptor drum.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic representation of a xerographic reproducing apparatus incorporating the advanceable photoreceptor construction forming a part of this invention; and Figure 2 is a schematic side elevational view, partly in section, of an advanceable photoreceptor construction representing the invention.

Referring now to the drawings, especially Figure 1, there is disclosed an automatic xerographic reproducing machine or apparatus 9. The automatic xerographic reproducing machine includes an advanceable photoreceptor in the form of an elongated flexible web comprising a photoconductive layer on a conductive backing which is partially trained over the outer surface of a hollow drum. The drum is supported in rotation which causes the plate surface to sequentially pass a series of xerographic processing stations.

For purposes of the present disclosure the several xerographic processing stations in the path of movement of the plate surface may be described functionally as follows: a charging station A where a uniform electrostatic charge is deposited onto the photoconductive plate; an exposure station B, at which light or radiation patterns of copies to be reproduced are projected onto the plate surface to dissipate the charge in the exposed areas thereof, to thereby form latent electrostatic images of the copies to be reproduced; a developing station C, at which xerographic developing material including toner particles having an electrostatic charge opposite to that of the latent electrostatic images is cascaded over the latent electrostatic images to form powder images in configuration of the copy being reproduced;; a transfer station D, where the powder images are electrostatically transferred from the plate surface to a transfer material such as paper, which then is passed through a heated pressure fusing system according to the present invention as will be described hereinafter; and a drum cleaning and discharge station E, at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and at which the plate is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.

For further details of the xerographic processing stations discussed above, reference may be had to U.S. Patent No. 3,578,859.

The advanceable photoreceptor as disclosed in Figure 2 is supported on the hollow drum 12 which is journalled for rotational movement in a clockwise direction as viewed in Figure 2 by means of a drum shaft (not shown).

A quantity of photoreceptor or photosensitive material in the form of elongated web 20 is supported relative to the drum 12 such that the bulk thereof is contained internally of the hollow drum while a portion 22 thereof is trained over the outer surface of the drum.

A supply roll 24 rotatably supported within the drum 12 serves to support unused photoreceptor material while a roll member 26 serves as a takeup roll for storing used photoreceptor material. As can be seen in Figure 2, one end of the photosensitive web 20 is attached to the takeup spool or roll 26 and passes through a slot 28 in the drum 12. The opposite end of the web is attached to the supply spool 24 and also passes through the slot 28.

In order to incrementally move the takeup spool 26, there is provided an actuator assembly generally indicated 30 which comprise an actuator arm 31 which is pivotably mounted to the drum 12 and adapted to be reciprocated about a pin 32 first in a clockwise direction as viewed in Figure 2 and then in a counterclockwise direction, the counterclockwise movement being effected by a bias spring 33 and the clockwise direction being effected by means of a two-step cam 34 through its engagement with a roller member 36 carried by the end opposite the pin 31 of the actuator arm 31. The two-step cam 34 is stationarily mounted to the machine frame 38 such that the roller 36 engages lobes 40 and 401 once for each revolution of the drum 12 in the clockwise direction.

A pair of pinch rolls 42 and 44 are provided for effecting unwinding of the web 20 from the supply roll 24, the roll 44 being supported by the drum structure 12 and the roll 42 being carried by the pin 32. A one-way clutch (not shown) couples the roll 42 to the pin 32 such that there is no relative movement there between when the arm 31 is pivoted in the clockwise sense but rotation of the roll 42 is permitted when the arm is pivoted in the opposite sense. This arrangement of the roll 42 will effect a functional pull on the web 20 only with clockwise pivoting of the arm 31, to thereby accomplish the aforementioned unwinding. The roll 42 rolls on the web 20 with pivoting of the arm 31 in the opposite sense.

The quantity of web 20 unwound from the supply roll 24 is wound onto the takeup roll 26 by means of a pawl 46 and a ratchet 48 which ratchet is operatively coupled to the roll 26 by means of a slip clutch (not shown) which allows the ratchet 48 to rotate relative to the roll 26 once the increment of web 20 unwound from the supply roll 24 has been wound onto the takeup roll. Actuation of the ratchet 48 to thereby cause it to rotate in the counterclockwise direction is effected by means of the bias spring 33 when the roller 36 engages the low sides of the cam 34. A drag member in the form of a spring 50 keeps the web taut coming from the supply roll 34. Also, a stop member 52 limits the counterclockwise movement of the arm 31.

The actuator mechanism 30 is designed to effect movement of 0-001 inch of photosensitive web material per each actuation thereof by one of the lobes 40, 401. Where the drum 12 has a diameter of 8 inches the circumference is approximately 24 inches.

Accordingly, approximately 24,000 copies can be made with the portion of photoreceptor material on the outer surface of the drum 12 before the complete portion has been replaced by photoreceptor material from the supply roll 34. Stated differently, if one considers a fragment of the photoreceptor material equal to 0-001 inch which is initially disposed adjacent the slot 28 at the supply roll side of the drum, it can be seen that the segment will be displaced 0-002 inch for each revolution of the drum and therefore when the drum has rotated 12,000 revolutions the aforementioned segment will be adjacent the slot 28 but at the side thereof adjacent the takeup spool.Since the photoreceptor 10 is capable of making two copies per revolution of the drum 12 it can be seen that each segment of the photoreceptor material will be utilized 24,000 times.

WHAT WE CLAIM IS: 1. Advanceable photoreceptor apparatus comprising a hollow drum having a slot substantially coextensive with the longitudinal axis of said drum, said drum being adapted for rotational movement, means for supporting a major portion of an electrophotosensitive web including both ends thereof internally of said drum while a smaller portion thereof is trained over the outer surface of said hollow drum, and means for automatically effecting regular incremental advance of said electrophotosensitive web round said drum during each revolution of said drum.

2. Apparatus according to Claim 1 including the electrophotosensitive web.

3. Apparatus according to Claim 1 or 2 wherein said means for supporting a major portion of said electrophotosensitive web comprises a supply roll and takeup roll.

4. Apparatus according to Claim 3 wherein said means for effecting incremental advance comprises a ratchet and pawl mechanism and cam actuator therefor which is operatively coupled to said takeup roll.

5. Apparatus according to Claim 4 wherein said mechanism comprises an actuator arm supported by said drum for reciprocatory movement and said cam means comprises a two-lobe cam stationarily supported adjacent said drum in a position to engage said actuator arm.

6. Apparatus according to any preceding Claim wherein the incremental advance of said electrophotosensitive web is of the order 0-002 inch per revolution.

7. A method of advancing an electrophotosensitive web supported by a hollow drum having a major portion of said web including both ends thereof supported internally of said drum and a smaller portion supported on the surface thereof, said method including the steps of rotating said drum with said smaller web portion passing a plurality of xerographic processing stations, and effecting regular incremental advance of said electrophotosensitive web during each revolution of said drum.

8. A method according to Claim 7 wherein said major portion of said web is supported on supply and takeup rolls and said step of effecting incremental advance of said web comprises effecting incremental rotation of said takeup roll during each revolution of said drum.

9. A method according to Claim 8 where m incremental rotation of said takeup roll is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   33 and the clockwise direction being effected by means of a two-step cam 34 through its engagement with a roller member 36 carried by the end opposite the pin 31 of the actuator arm 31. The two-step cam 34 is stationarily mounted to the machine frame 38 such that the roller 36 engages lobes 40 and 401 once for each revolution of the drum 12 in the clockwise direction.

   A pair of pinch rolls 42 and 44 are provided for effecting unwinding of the web 20 from the supply roll 24, the roll 44 being supported by the drum structure 12 and the roll 42 being carried by the pin 32. A one-way clutch (not shown) couples the roll 42 to the pin 32 such that there is no relative movement there between when the arm 31 is pivoted in the clockwise sense but rotation of the roll 42 is permitted when the arm is pivoted in the opposite sense. This arrangement of the roll 42 will effect a functional pull on the web 20 only with clockwise pivoting of the arm 31, to thereby accomplish the aforementioned unwinding. The roll 42 rolls on the web 20 with pivoting of the arm 31 in the opposite sense.

   The quantity of web 20 unwound from the supply roll 24 is wound onto the takeup roll 26 by means of a pawl 46 and a ratchet 48 which ratchet is operatively coupled to the roll 26 by means of a slip clutch (not shown) which allows the ratchet 48 to rotate relative to the roll 26 once the increment of web 20 unwound from the supply roll 24 has been wound onto the takeup roll. Actuation of the ratchet 48 to thereby cause it to rotate in the counterclockwise direction is effected by means of the bias spring 33 when the roller 36 engages the low sides of the cam 34. A drag member in the form of a spring 50 keeps the web taut coming from the supply roll 34. Also, a stop member 52 limits the counterclockwise movement of the arm 31.

   The actuator mechanism 30 is designed to effect movement of 0-001 inch of photosensitive web material per each actuation thereof by one of the lobes 40, 401. Where the drum 12 has a diameter of 8 inches the circumference is approximately 24 inches.

   Accordingly, approximately 24,000 copies can be made with the portion of photoreceptor material on the outer surface of the drum 12 before the complete portion has been replaced by photoreceptor material from the supply roll 34. Stated differently, if one considers a fragment of the photoreceptor material equal to 0-001 inch which is initially disposed adjacent the slot 28 at the supply roll side of the drum, it can be seen that the segment will be displaced 0-002 inch for each revolution of the drum and therefore when the drum has rotated 12,000 revolutions the aforementioned segment will be adjacent the slot 28 but at the side thereof adjacent the takeup spool.Since the photoreceptor 10 is capable of making two copies per revolution of the drum 12 it can be seen that each segment of the photoreceptor material will be utilized 24,000 times.

   WHAT WE CLAIM IS: 1. Advanceable photoreceptor apparatus comprising a hollow drum having a slot substantially coextensive with the longitudinal axis of said drum, said drum being adapted for rotational movement, means for supporting a major portion of an electrophotosensitive web including both ends thereof internally of said drum while a smaller portion thereof is trained over the outer surface of said hollow drum, and means for automatically effecting regular incremental advance of said electrophotosensitive web round said drum during each revolution of said drum.
2. 2. Apparatus according to Claim 1 including the electrophotosensitive web.
3. 3. Apparatus according to Claim 1 or 2 wherein said means for supporting a major portion of said electrophotosensitive web comprises a supply roll and takeup roll.
4. 4. Apparatus according to Claim 3 wherein said means for effecting incremental advance comprises a ratchet and pawl mechanism and cam actuator therefor which is operatively coupled to said takeup roll.
5. 5. Apparatus according to Claim 4 wherein said mechanism comprises an actuator arm supported by said drum for reciprocatory movement and said cam means comprises a two-lobe cam stationarily supported adjacent said drum in a position to engage said actuator arm.
6. 6. Apparatus according to any preceding Claim wherein the incremental advance of said electrophotosensitive web is of the order 0-002 inch per revolution.
7. 7. A method of advancing an electrophotosensitive web supported by a hollow drum having a major portion of said web including both ends thereof supported internally of said drum and a smaller portion supported on the surface thereof, said method including the steps of rotating said drum with said smaller web portion passing a plurality of xerographic processing stations, and effecting regular incremental advance of said electrophotosensitive web during each revolution of said drum.
8. 8. A method according to Claim 7 wherein said major portion of said web is supported on supply and takeup rolls and said step of effecting incremental advance of said web comprises effecting incremental rotation of said takeup roll during each revolution of said drum.
9. 9. A method according to Claim 8 where m incremental rotation of said takeup roll is

   effected by means of a ratchet and pawl mechanism supported by said drum and cam means stationarily supported adjacent said drum.
10. 10. Advanceable receptor apparatus substantially as described herein with reference to the accompanying drawings.
11. 11. A method of advancing an electrophotosensitive web substantially as described herein with reference to the accompanying drawings.