US3754819A

US3754819A - Apparatus for placing rollers in contact in a pressure fuser assembly

Info

Publication number: US3754819A
Application number: US00214304A
Authority: US
Inventors: O Braun
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1971-12-30
Filing date: 1971-12-30
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28
Also published as: NL7214958A

Abstract

A cam assembly is mounted on an electrostatographic machine in contact with a structure bar of a pressure roller assembly. Upon activation of a motor, the cam shaft is caused to rotate through a suitable gearing arrangement thereby swinging the assembly about an axis to place the pressure roller in contact with the fuser roller. Upon reaching the end stop position, a solenoid is activated to lock by appropriate linkage the rollers in operational position. Upon deactivation of the solenoid the cam shaft is caused to rotate to its standby position by a torsional spring affixed to the shaft and to the support assembly.

Description

[ Aug. 28, 1973 United States Patent Braun Tregay et 6/1969 Stryjewski...........................

[541 APPARATUS FOR PLACING ROLLERS IN 3,398,259 8/1968 CONTACT IN A PRESSURE FUSER 3.4521181 ASSEMBLY [75] Inventor:

einer a m .m h C A d r a n r e .B om M o "a ma R J r ma m. J mew m 1 m nil PA Oskar Braun, Williamson, N. Y. Assignee: Xerox Corporation, Stamford, Conn.

22 Filed:

and Louis E. Marn et a1.

[57 ABSTRACT A cam assembly is mounted on an electrostatographic 1 machine in contact with a structure bar of a pressure roller assembly. Upon activation of a motor, the cam Dec. 30, 1971 [21] App]. No.: 214,304

shaft is caused to rotate through a suitable gearing arrangement thereby swinging the assembly about an axis to place the pressure roller in contact with the fuser [51] Int. Cl.

1105b 3/10, 603g 15/20 [58] Field of Search 355/3; 219/216, 388,

2|9/469; 263/6 34/1 10, 1 1 17/21 roller. Upon reaching the end stop position, a solenoid is activated to lock by appropriate linkage the rollers in operational position. Upon deactivation of the solenoid the cam shaft is caused to rotate to its standby position by a torsional spring affixed to the shaft and to the support assembly.

3,449,548 Adamek et a1. 219/388 x 3,211,074 Heiart et 219/216 7 Claims, 4 Drawing Figures Patented Aug. 28, 1973 2 Sheets-Sheet l Patenfed Aug. 28 1973.

i 2 Sheets-Sheet '2 BACKGNOUNI) OF THE INVENTION This invention relates to electrostatography, and more'particularly to apparatus for placing a fuser roller and a pressure roller in contact in an electrostatographic apparatus. I

In the practice of xerography as described in US. Pat No. 2,297,6 9l to Chester F. Carlson, a xerographic surface comprising a layer of photoconductive insulat-' ing material affixed-to a conductive backing is used to support electrostatic/images. In the usual method of carrying out the process, the xerographic plate is electrostaically charged uniformly over its surface and then exposed to a light pattern of the image being-reproduced to thereby discharge the charge in the areas where light strikes'the layer; The undisch'arged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original light pattern.

The latent electrostatic image may then be developed by contacting it with a finely divided electrostatically attractable material, such as a resinous powder. The

powder isheld "in the image areas by the electrostatic fields on the layer; Where the field is greatest, the greatest amount'of material is deposited; and where the field is'least, little orno material is deposited. Thus, a powderimage is'produced in conformity with the light image of the copy being reproduced. The powder is subsequently transferred "to a sheet of paper or other surface and suitably affixed, such as by heat, pressure, andth'e like,'to thereby form a. permanent print.

The toner may be fixed passing the sheet of paper or other surface including the transferred'image be- SUMMARY OF THE INVENTION These and other objects of the invention'are obtained by providing a fuser assembly including a fuser roller, a pressure roller mounting assembly, and a cam assembly operatively associated with the pressure roller assembly. The pressure roller mounting assembly is pivotally mounted to the frame assembly above the fuser roller mounted for rotation therein. Activation of the cam assembly causes the pressure roller mounting assembly to move downwardly to place the pressure roller in contactwith the fuser roller. At the termination of the loading cycle, the cam assembly is locked in place. Upon release of the locking'means, the force of torsion'springs and the inertia of the cam causes the cam shaft to rotate thereby pennitting the pressure roller to move away from the fuser roller.

DESCRIPTION OF THE DRAWINGS A better understanding of the present invention as well as other objects and further features thereof will tween a heated roller and a second roller in pressure OBJECTS OF THE INVENTION An object of this invention is to provide a novel fuser assembly for an electrostatographic machine.

' Another object of thisinverition is to'provide a novel apparatus forplacing the fuser and pressure rollers in contact for an image transfer mode of an electrostatographic machine. I

Still another object of the invention is to provide a novel apparatus for ensuring uniform pressure between the fuser and'pressure rollers of an electrostatographic machine.

A still further object of the invention is to provide a novelcam loading assembly for placing the fuser and pressure rollers in contact for an image transfer mode of' an electrostatographic machine and for separating such'rollers for other modes thereof, e.g when the machine is in a standby mode.

become apparent upon consideration of the following detailed disclosure thereof, especially when taken with the accompanying drawings, wherein like numerals designate like parts throughout.

FIG. 1 is a schematic sectional view of an electrostatic reproduction machine embodying the principles of the invention;

FIG. 2 is a side view of the pressure roller assembly 'illustratingthe positioningof the pressure roller in an image transfer mode;

FIG. 3 is a partial sectional isometric view of the fuser assembly; and

FIG. 4 is an enlarge exploded isometric view of the duce image rays corresponding to the informational ar-' eas. The image rays are projected by means of an optical system onto the photosensitive surface of a xerographicplate in the form of aflexible photoconductive belt 12 arranged'on a belt assembly, generally indicated by the reference numeral 14,

'- The belt 12 comprises a photoconductive layer of selenium which is'the light receiving surface and imaging medium for the apparatus, on a conductive backing. The surface of the photoconductive belt is made photosensitiveby a-previous step of uniformly charging the same by means of a corona generating device or corotron 13.

The belt is joumaled for continuous movement upon three rollers 20, 21 and 22 positioned with their axes in parallel. The photoconductive belt assembly 14 is slidably mounted upon two support shafts 23 and 24 with the roller 22 rotatably supported on the shaft 23 which is secured to the frame of the apparatus and is rotatably driven by a suitable motor and drive assembly (not shown.) in the direction of the arrow at a constant rate. During exposure of the belt 12, the portion exposed is that portion of the belt running between rollers trostatic image passes'through a developing station B in than one may be employed) is affixed to the cam shaft 63 and to the frame 48 to assist in the separation of the rollers at the termination of an image transfer mode.

In operation upon activation of the machine such as by the depression of a button by the operator, the element 36 is energized and heats the fuser roller 30 to an which there is positioned a developer assembly generally indicated by the reference numeral 15, and which provides development of the electrostatic image by means of multiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to a transfer station C whereat a sheet of copy paper is moved between a transfer roller and the belt operational temperature range, at which time the machine shifts into a standby mode ready to be placed in an image transfer mode. Generation of a signal to place the machine in production energizes a clutch in a drive means, generally indicated as 90, to drive gear 66 which rotates gear 64 thereby causing the cam shaft 63 including cams 62 to rotate clockwise (as shown by the at a speed in synchronism with the moving belt in order to accomplish transfer of the developed image solely by an electrical bias on the transfer roller. There is provided at this station a sheet transport mechanism generally indicated at 17 adapted to transport sheets of paper from a paper handling mechanism generally indicated by the reference numeral 18 to developed image on the support therefor may be found in the copending Application Ser. No. 102,312 assigned to the same assignee.

Referring now to FIGS. 2 and 3, the fuser assembly 19 of this invention is comprised of a fuser roller 30 and a pressure roller assembly, generally indicated as 32, including a pressure roller 34. The fuser roller 30 is formed of a suitable heat conductive material, such as copper and is provided with a source of heat 36, such as a quartz lamp, centrally positioned therein to heat the roller 30 to operational temperatures. The pressure roller 32 is mounted for rotation in end plates 38..A support bar 40 and a cam follower shaft 42 including suitable bearing means 44, are mounted to end plates 38. A pivot shaft 46 is affixed to and extends through the end plate 38 and is mounted for rotation in fuser frame assembly,,generally indicated as 48. a

The cam assembly, referring now to FIG. 4, generally indicated as 60, includes cams 62 mounted on a cam shaft 63, one end of which extends through the frame 48 and is provided with a gear 64 having an internally formed cammed surface 65. The gear 64 engages a drive gear 66, as more fully hereinafter described. A

small cam 66 is positioned on the shaft in juxtaposition to a switch assembly, generally indicated as 68 including two switches. A linking latch 70 including a latching surface 72 is mounted for rotation to the frame 48, such as by screw 74 in a manner to contact the latching surface 72 at the termination of the loading cycle. One end of a spring 76 is affixed to the linking latch 70 with the other end affixed to the frame 48. A lever 80 is positioned below the linking latch 70 and is mounted for rotation to the frame 48 such as by screw 82. One end of the lever 80 is engage by a plunger 84 of a solenoid, generally indicated as 86. A torsion spring 88 (more arrow) simultaneously winding torsion spring 88. Upon rotation through a predetermined angle, the cam 66 actuates the switch assembly 68, one switch therein deenergizes the clutch in the drive mechanism while the other switch energizes solenoid 86. Activation of the solenoid 86 causes the plunger 84 thereof to move upwardly thereby lifting lever 80 which raises latching link to a point where the latching surface 72 engages the surface 65 of the gear 64 thereby locking the cam shaft63 in the image-fusing mode, i.e., the counterclockwise movement of the cam shaft 63 is. prevented. The pressure roller assembly thus moves from the position of thestandby mode, illustrated by the dotted lines in FIG. 2, to the operational position illustrated by the solid lines therein. l

Upon generation of a signal indicative of the completion of the vimage fusing mode, the solenoid is deenergized to permit thetensioning pressure of spring 76 to move the latching surface 72 downwardly away from the cammed surface 65 thereby permitting'the cam shaft 63 to rotate counterclockwise by the force of spring 88 and naturalinertia of the cams to return the pressure roller to'its position in the standby mode of the machine. 1 a k 1 While the operation of the fuser assembly has been described with reference to the unloading-of the'pressure roller in response toa signal (e.g., developed in response to a signal. that the production run is completed), it is understood that unloading may also be effected automatically in response to a signal generated by other means, e.g., overheating of the heating ele-.

ment in the fuser roller 30, paper jams, etc.

While the instant invention as to its objects and advantages has been described herein as carried in specific embodiments thereof, it is not desired to be lim-' ited thereby; but it is intended to cover the invention broadly within the scope .of the appended claims.

' What is claimed is: I

f l. A fuser roller assembly'for an electrostatographic machine including a fuser roller and a pressure roller, which comprises; i

a. a pressure roller assembly in which said pressure roller is mounted for rotation, said pressure roller assembly being pivotally mounted in juxtaposition to said fuser roller within said machine and provided with cam following surface means;

' b. acam assembly including cam means disposed in said machine with said cam means thereof contacting said cam following surface means c. drive means for rotating said cam assembly to cause said pressure roller assembly to move towards said fuser roller to a point where said pressure roller contacts said fuser roller in an image 1 transfer mode of said machine;

d. spring means for moving said pressure roller assembly away from said fuser roller, said drive means being adapted to place said spring means under torsional pressure during rotation of said cam means to said image transfer mode; and

e. locking means cooperable with said cam assembly after rotation of said cam assembly and said spring means through a predetermined angle to prevent counter rotation of said cam assembly and moving of said pressure roller assembly away from said fuser roller by said spring means.

2. The apparatus as defined in claim 1 wherein said locking means is engaged by movement of a solenoid means.

3. The apparatus as defined in claim 2 wherein said electrostatographic machine has means to provide a signal following said image transfer mode,

and means to deactivate said solenoid means and disengage said locking means in response to said signal.

4. The apparatus as defined in claim 2 wherein said solenoid means is activated by a switch activated by a cam means mounted on a shaft of said cam assembly.

5. The apparatus as defined in claim 1 wherein said drive'means is deactivated by a switch activated by a cam meansmounted on a shaft of said cam assembly.

6. The apparatus as defined in claim 1 wherein said electrostatographic machine has means to provide a signal responsive to said image transfer mode;

and means for activating said drive means in response to said signal.

7. in the fusing apparatus adapted for use with copy producing machines of the type comprising a roller pair in pressure relationship, with at least one of said rollers being heated, the combination of:

means supporting said rollers for movement relative to one another in to and out of pressure relationship;

drive means adapted when actuated to move said rollers into pressure relationship;

bias means adapted when loaded and activated to move said rollers apart, said drive means serving when actuated to load said bias means in preparation for subsequent release of said rollers;

means for locking said rollers in pressure relationship with said bias means in a preset loaded condition, ready to move said rollers apart; and

means to release said locking means and activate said bias means whereby said bias means moves said rollers apart. I

Claims

1. A fuser roller assembly for an electrostatographic machine including a fuser roller and a pressure roller, which comprises; a. a pressure roller assembly in which said pressure roller is mounted for rotation, said pressure roller assembly being pivotally mounted in juxtaposition to said fuser roller within said machine and provided with cam following surface means; b. a cam assembly including cam means disposed in said machine with said cam means thereof contacting said cam following surface means c. drive means for rotating said cam assembly to cause said pressure roller assembly to move towards said fuser roller to a point where said pressure roller contacts said fuser roller in an image transfer mode of said machine; d. spring means for moving said pressure roller assembly away from said fuser roller, said drive means being adapted to place said spring means under torsional pressure during rotation of said cam means to said image transfer mode; and e. locking means cooperable with said cam assembly after rotation of said cam assembly and said spring means through a predetermined angle to prevent counter rotation of said cam assembly and moving of said pressure roller assembly away from said fuser roller by said spring means.

3. The apparatus as defined in claim 2 wherein said electrostatographic machine has means to provide a signal following said image transfer mode, and means to deactivate said solenoid means and disengage said locking means in response to said signal.

5. The apparatus as defined in claim 1 wherein said drive means is deactivated by a switch activated by a cam means mounted on a shaft of said cam assembly.

6. The apparatus as defined in claim 1 wherein said electrostatographic machine has means to provide a signal responsive to said image transfer mode; and means for activating said drive means in response to said signal.

7. In the fusing apparatus adapted for use with copy producing machines of the type comprising a rOller pair in pressure relationship, with at least one of said rollers being heated, the combination of: means supporting said rollers for movement relative to one another in to and out of pressure relationship; drive means adapted when actuated to move said rollers into pressure relationship; bias means adapted when loaded and activated to move said rollers apart, said drive means serving when actuated to load said bias means in preparation for subsequent release of said rollers; means for locking said rollers in pressure relationship with said bias means in a preset loaded condition, ready to move said rollers apart; and means to release said locking means and activate said bias means whereby said bias means moves said rollers apart.