US3388688A

US3388688A - Electrophotographic apparatus

Info

Publication number: US3388688A
Application number: US561849A
Authority: US
Inventors: Arthur J Stanton
Original assignee: Harris Intertype Corp
Current assignee: Harris Graphics Corp
Priority date: 1966-06-30
Filing date: 1966-06-30
Publication date: 1968-06-18
Anticipated expiration: 1985-06-18

Description

June 18, 1968 A. J. STANTON 3,388,688

ELECTROPHOTOGRAPHIC APPARATUS Filed June 30, 1966 2 Sheets-Sheet United States Patent 3,388,688 ELECTROPHOTOGRAPHIC APPARATUS Arthur J. Stanton, Warrensville Heights, Ohio, assignor to Harris-Intertype Corporation, Cleveland, Ohio, a

corporation of Delaware Filed June 30, 1966, Ser; No. 561,849 8 Claims. (Cl. 118-637) ABSTRACT OF THE DISCLOSURE A developer unit for use with an electrophotographic apparatus wherein a sheet bearing an electrostatic image on one side is directed downwardly by guide elements into a liquid developer and then undergoes a change in direction so that the sheet leaves the developer traveling in a generally upwardly direction. No relative movement occurs between the image side of the sheet and any surface or component of the developer unit. Those surfaces in contact with the image side of the sheet are electrically insulating and are moved at the same velocity as the sheet to prevent distortion ofthe electrostatic image. Only the leading and trailing edges of the sheet are allowed in sliding contact with the stationary guide elements within the developer unit.

This invention relates to a developer unit for an electrophotographic apparatus and more particularly to such a unit for use in developing sheet members in a liquid developer wherein the sheet bearing an electrostatic latent image is immersed and passed through the developer in such fashion that the surface thereof having the image thereon is free from contact with any stationary surface thereby to avoid blurring, streaking or marring of the developed image. I

In the operation of an electrostatic photographic device, such as described in copending application Ser. No. 346,718, filed Feb. 24, 1964, a sheet of paper is first advanced through a charging station where the sheet is charged and then advanced into an exposing station where a light image of an original document is projected thereon to cause formation of an electrostatic latent image charge corresponding to the original. The sheet is thereafter advanced into and through a developer liquid containing charged marking particles in an electrically insulating carrier liquid wherein the marking particles are deposited as controlled by the latent image and form a visible copy of the original. As the sheet leaves the developing station, excess carrier liquid is removed by passing the sheet between a pair of rollers acting as a squeegee and the sheet thereafter travels through a heating station to remove the remainder of the liquid and to effect substantially permanent adhesion of the marking particles to the surface of the image bearing sheet member.

While the sheet is in contact with liquid developer, relative motion between the image side of the sheet and any portion of the developer unit may cause the image to be distorted or smeared during development. As the sheet bearing the latent image is passed through the liquid developer in the preferred embodiment of the invention, the sheet undergoes a change in direction, from a generally vertically downward movement into the developer to a generally vertically upward movement out of the developer unit. This change in direction is eifected while the sheet is in liquid developer by guiding the sheet through the developer unit but at the same time substantially eliminating any relative sliding contacting movement between the image side of the sheet and any surface or component of the developer unit.

The present invention therefore relates to a developer Patented June 18, 1968 unit wherein the sheet is directed into the developer liquid, and during contact with the developer, any sliding contact between the image side of the sheet and any part of the unit is eliminated. The developer unit receives a sheet from the exposing station, and includes guide elements to direct the sheet into the developer and to guide the image side of the sheet away from any stationary surface. Some of the surfaces in contact with the image side of the sheet may be electrically insulating and are moved at the same linear velocity as the surface of the sheet. Only the leading and trailing edges of the sheet are allowed in sliding contact with the guide elements of the developer unit while the image side of the sheet is kept free from sliding contacting movement with the stationary components of the developer unit.

Accordingly, it is an object of this invention to provide a developer unit for use in an electrophotographic apparatus wherein a sheet bearing electrostatic latent image is so guided while in a liquid developer that sliding contacting movement between the image side of the sheet and any part or component of the developer unit is Substantially eliminated.

It is another object of this invention to provide a developer unit including fixed and rotatable guides so arranged that a sheet bearing an electrostatic latent image is lifted away from all stationary surfaces so that the electrostatic latent image on the sheet is not streaked or marred by any rubbing with stationary parts as the sheet is guided through the developer.

It is another object of the present invention to provide a compact developer unit of the type described for developing an electrostatic latent image on a sheet membet with a liquid developer, the developer unit including a generally U-shaped developing channel at least part of which is below the level of the liquid developer, the channel being formed by rotatable elements, fixed elements in sliding contact with the non-image side of the sheet at spaced intervals, and additional fixed elements functioning as guides in contact with only the leading and trailing edges of the sheet thereby substantially eliminating any sliding contact of the image side of the sheet with any element as the sheet travels through the channel.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

FIG. 1 is a front elevational view of a liquid developer unit constructed according to this invention with some of the component parts broken away to reveal other parts situated therebehind;

FIG. 2 is a cross-sectional view taken along line 22 in FIG. 1;

FIG. 3 is an end view of the developer unit particularly showing the gearing arrangement usedto drive the unit; and

FIGS. 4-10 are simplified views of portions of a developer unit in accordance with this invention showing the path taken by a sheet of paper as it passes through the unit.

Referring to the drawings, which show a preferred embodiment of the present invention, the developer unit in FIGS. 1 and 2 is mounted on a base 10 and includes a tank 11 having a pair of vertically mounted

end wall members

12 and 13 and a pair of upwardly sloping diverging wall members 14. A pair of

end plates

15 and 16 removably support the developer mechanism within the tank 11;

Spacer rods

18 and 18 are secured to the end plates to provide rigidity and support. A liquid developer may be introduced into the tank through aninlet pipe 20 extending through the wall member 12, and the developer may be removed through a discharge pipe 21 mounted at the bottom of the tank and extending through the wall member 14. The normal level of the developer fluid in the tank is shown by a dashed line 22 in FIG. 2.

An agitator mechanism 23 is provided in the tank to insure a uniform dispersion of marking particles throughout the electrically insulating carrier liquid. This agitator consists of four paddle wheels 25 keyed to a hub 26, and mounted on shaft 27 which rotates in end plates and 16. The hub 26 is locked to the shaft 27 by a set screw 28. The agitator paddles are enclosed within a deflector assembly 30 and consist of a curved deflect-or plate 31 and three substantially

identical plates

32, 33 and 34 each mounted at their ends by screws 35 to a pair of support plates 36, only one of which is shown in FIG. 2. Each of the support plates 36 is secured to one of the

end plates

15 and 16 by screws (not shown), and the agitator mechanism is positioned between the support plates 36. Each of the deflector plates 32-34 is provided with a plurality of openings as shown in FIG. 1, through which the liquid developer may freely pass, thus allowing the agitator to mix and distribute the marking particles continuously through the carrier liquid.

As shown in FIG. 2, each support plate 36 includes a plurality of spaced flat faces on the lower portion thereof which receive one of the plates 32-34 so that a portion 32a-34a of each plate 32-34, respectively, extends beyond the periphery of the support plate as shown. The plates 32-34 extend across the width of the developer unit as shown in FIG. 1. Curved deflector plate 31 also includes an extending portion 31a which likewise extends beyond the periphery of support plates 36. The extending portions 31a-34a of plates 31-34 are adapted to contact the nonimage side of the sheet in sliding contacting relationship at the spaced intervals along the length of the sheet. Since these extending portions are aligned at right angles to the path of sheet travel, only line contact is made between the sheet and extending portions of the plate with the result that the non-image side of the sheet is substantially free of guide or streak marks.

A sheet of paper having an elctrostatic latent image thereon is directed into the developing unit through

guides

40 and 41 which extend across the unit and the leading edge of the sheet then received between a driven roll 42 mounted on a shaft 43 and pressure roll 44 which is mounted on shaft 45. The image side of the sheet is positioned to contact the pressure roll 44. The shaft 43 extends through end plate 16 where it is driven through a suitable gearing arrangement, later to be described. The pressure roll 44 is journalled between lever arms 46, each of which is pivoted on pin 47 and urged into engagement with the driven roll 42 by springs 48. While only one lever arm assembly is shown, it is understood that both ends of the shaft 45 are similarly mounted.

As the sheet is fed into the developer unit, the leading edge thereof is picked up by

rolls

42 and 44 which drive the sheet beneath the level of the liquid developer. The

rolls

42 and 44 are arranged so that the sheet tends to leave the

rolls

42 and 44 in a direction perpendicular to an imaginary line drawn between the centers of theroll. Thus, as the leading edge of the sheet leaves the nip of

rollers

42 and 44 it will be directed against deflector plate 31 as shown in FIG. 4. As the sheet is advanced further, the leading edge thereof will pass over the edge portion 31a of deflector plate 31, and come into contact with a plurality of curved cam blades 51 which serve as a first camming means.

Each of the cam blades includes a concave shaped camming surface which faces the agitator mechanism 23 and the cam blades are held in alignment by pair of

shafts

52 and 53 which extend between the

end plates

15 and 16. The cam blades are spaced from each other by spacers 54 between each cam blade. The blades, which form first camming means are so arranged with respect to

deflector plates

31 and 32 that the leading edge of the sheet plate is directed toward a deflector roll 57.

The deflector roll 57, mounted on shaft 58, is positioned to receive the leading edge of the sheet from the cam blades 51 and dire-ct it toward a second set of cam blades 62. The shaft 58 is journalled at one end in end plate 15, while the other end of the shaft passes through the other end plate 1-6 where it is so rotated that the tangential velocity of the roll 57 is the same as the linear velocity of the sheet at the point of contact thereby preventing relative motion beween the sheet and the roll. This is necessary in order to prevent blurring, streaking and marring of the image side of the sheet. As an additional precaution against unwanted marking of the sheet, a scrubber assembly 61 consisting of a flexible pad of a spongy material is mounted in sliding contact with the deflector roll 57 at a point remote from the point of contact with the sheet. The scrubber functions to clean the roll and to remove any deposit of marking particles which may be accumulated thereon.

The second set of cam blades 62 function as a second camming means and each blade is essentially the same as blades 51 except that the lower ends are rounded, as shown, to permit easy passage of the leading edge thereon. Each cam blade 62 is so mounted that the camming surface faces the agitator mechanism 23, and the cam blades 62 are arranged to make sliding contact with the leading edge of the sheet as it passes through the developer tank. Each blade 62 is mounted on shafts 63 and 64 and maintained in alignment by spacer members similar to that shown with the first set of cam blade-s 51.

The second set of cam blades guides the leading edge of the sheet to rolls 70 and 71 mounted for rotation on

shafts

72 and 73, respectively. Roll 70 is driven and roll 71 is a pressure roll journalled between a pair of levers 74 pivoted on pin 75 and urged into engagement with the driven roll by a spring 76. The spring 76 will create sufficient compression between the pressure roll and the driven roll to remove a substantial portion of the developed carrier liquid as the sheet moves upwardly out of the developer.

The

rolls

70 and 71 are arranged in such a manner that the image side of the sheet will be lifted away from the surface of the second set of cam blades 62 as the sheet moves onto the nip of

rolls

70 and 71 and thus, the nonimage side of the sheet will be urged against the

deflectors

33 and 34 when the sheet begins to pass between both

rolls

70 and 71.

A scrubber pad 78 is mounted on the tank wall 14 and runs the length of the pres-sure roll 71 to clean it and to remove any accumulation of marking particles which maybe deposited thereon. A further scrubber 79, mounted on end plate 36, extends the length of roll 70 and removes any deposit of marking particles therefrom. A portion of each of

scrubbers

78 and 79 is always in contact with the liquid developer so that, through capillaiy action, these scrubbers are maintained moist and ready for use, even though the developer unit may stand idle for periods of time.

The sheet is then directed upwardly between the

guides

80 and 81 where it then passes to the drying station, as described in the above mentioned copending application. A switch 83 is mounted on the plate 81 and has an actuating arm 84 extending into the space between the

guides

80 and 81 to sense the presence of a sheet and is used to control the operation of the drying station.

Since relative movement between the sheet and any part within the developer unit would cause the blurring or streaking of the electrostatic image, it is necessary to insure that the moving surfaces within the tank which come in contact with the sheet have the same tangential velocity at the point of contact with the sheet as the linear velocity of the sheet. Therefore, each of the

rollers

44, 57 and 71 is rotated at a precisely controlled speed.

Referring now to FIGS. 1 and 3, power to the developer assembly to rotate these moving surfaces is obtained from a motor 87 and through

gears

88 and 89 to drive gear 90. Gear 90 is not only in engagement with gear 89, but also has a portion in engagement with the large gear 91. Gear 89 is fixed to the shaft 72 which causes the driven roll 70 to move the sheet upwardly out of the developer tank. The large gear 91 is fixed to shaft 27 and causes the agitator blades to rotate at a relatively slow speed, and at the same time drives gear 92 fixed to shaft 58 and the deflector roll 57, and also rotates driven roll 42 through a pair of

gears

93 and 94, the last named gear being fixed to shaft 43.

The non-image side of the sheet is engaged by the driven rolls 42 and 70 which insures that the pressure rolls 44 and 71 will rotate at exactly the same speed as the image side of the sheet since the pressure rolls are actually driven through the sheet itself. The deflector roll 57, being geared to the sheet moving mechanism, is also rotated at precisely the correct speed to insure absence of relative movement between the image side of the sheet and that roll.

Referring now to FIGS. 4-10 for a more complete understanding of the operation of this invention, a sheet 100 containing an electrostatic image on side 101 formed to correspond to the image on an original document is directed between the

guides

40 and 41. The sheet is received between the

rollers

42 and 44 which are arranged to direct the sheet into the tank assembly where the leading edge will engage the deflector plate 31 (FIG. 4). As the sheet continues to move into the tank, the leading edge slides down the deflector plate 31 until it contacts the camming surface of the blade members 51 (FIG. 5) which direct the leading edge toward the deflector roll 57 (FIG. 6). At this relative position, the non-image side 102 of the sheet is in sliding contact with the lower edge portion 31:; of the deflector plate 31. As the deflector roll 57 receives the leading edge of the sheet 100, the image side of the sheet will be lifted away from the camming surface of the first set of cam blades 51 (FIG. 7) so that the image side of the sheeet 100 will be free from sliding contact with any stationary surface. As pointed out previously, roll 57 is rotated with a tangential velocity which is the same as the linear velocity of the sheet moving through the tank.

The leading edge of the sheet will then make sliding contact with the surface of the second set cam blades 62 (FIG. 8) and be directed upwardly out of the developer solution. As the sheet continues to move upwardly, the leading edge enters the nip of rollers 70 and 71 (FIG. 9), and due to the orientation of the rolls, the sheet is lifted off of the surface of the second set of cam blade means 62 to eliminate again relative movement between the sheet and any stationary surface.

Rolls

70 and 71, in addition to acting as drive or pull through rolls, also remove carrier liquid as previously noted. The leading edge of the sheet continues upwardly through the

guide plates

80 and 81 and causes the actuating arm 84 of the switch to move and to commence the drying cycle.

As shown in FIG. 9, the non-image side 102 of the sheet engages the lower edge portion 31a of the deflector plate 31 and the extending portion 32a34a of deflectors 32-34, respectively. In this relative position of the sheet there is a portion of the sheet which has not yet entered the nip of

rolls

42, 44. While the image side of this portion of the sheet may contact guide 41, no streaking or marking has been observed because the guide 41 is out of the developer liquid. The image side of the sheet which is in the developer, however, is prevented from coming in contact with any stationary surface.

Rolls

70 and 71 are so arranged along the path of sheet travel that as the leading edge of the sheet enters the nip between them, rolls 42 and 44 are still driving the sheet. Thus, the linear distance along the path of travel between

rolls

70, 71 and 42, 44 is less than the length of the sheet.

As the trailing edge of the sheet is released by

rollers

42 and 44, it will fall and contact the upper portion of the first set cam blades 51, as shown by the dotted line (FIG.

10), which provide support for the remainder of the sheet. Since only the trailing edge of the sheet follows the camming surface of the cam blades, there is no sliding contact between the image side of the sheet and the cam blades 51. Thus, only the leading edge and the trailing edge of the sheet is in sliding contact with any stationary surface beneath the level of the liquid developer, and no smearing, streaking or marring of the image will therefore result as the sheet passes through the developer tank.

Thus, the developer unit of the present invention includes a tank, and the first set of cams cooperate with the opposed deflector plates to form a generally downwardly extending leg of a sheet receiving channel while the second set of cam plates and the opposed deflector plates form an upwardly extending leg of the channel. Positioned in the path of sheet travel and between the first and second set of cam plates is a roller which functions to lift the leading edge of the sheet and advance it to a second sheet of cam plates. In this way, there is no relative sliding movement between the image side of the sheet and any portion of the developer unit which is beneath the level of the liquid developer, and thus, streaking or marking of the image side of the sheet during development is substantially eliminated.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A unit for developing electrostatic images on a sheet with a liquid developer comprising:

a tank adapted to contain a liquid developer including marking particles in an electrically insulated carrier liquid;

means for receiving a sheet having an electrostatic latent image thereon and for directing the sheet into said tank;

first camming means positioned in said tank in facing relation to the image side of the sheet for receiving the leading edge of the sheet in sliding contact as it moves through said tank;

a deflector roll mounted in said tank for receivirig the leading edge of the sheet from the first camming means and for lifting the image side of the sheet off the surface of said first camming means thereby preventing sliding contacting movement between the image side of the sheet and said first camming means, said roll having a tangential Velocity the same as the linear velocity of the sheet to prevent relative movement therebetween;

second camming means positioned in said tank in fac ing relation to the image side of the sheet for receiving the leading edge of the sheet in sliding contact after it passes said deflector roll and for guiding the sheet upwardly and out of said tank;

means for receiving the sheet from said second camming means and advancing it upwardly out of said tank,

said last named means so arranged that the image side i of the sheet is lifted away from the surface of said second camming means thereby preventing relative sliding contacting movement between the image side of the sheet and said second camming means; and deflector means in spaced opposed relation to said first and second camming means to form therewith a sheet receiving channel, said deflector means comprising a plurality of blade members having edge portions mounted at right angles to the path of sheet travel and adapted to receive in sliding contact the nonimage side of said sheet. A 2. The developer unit defined in claim 1 further including a scrubber means mounted adjacent to and in sliding contact with said deflector roll for cleaning said roll and removing deposits of marking particles therefrom.

3. The developer unit as defined in claim 1 wherein said first and second camming means includes a plurality of curved blade members mounted with the edge portions thereof positioned to receive in sliding contacting movement the leading and trailing edges of said sheet thereby providing a minimum area of contact therewith.

4. A unit for developing electrostatic images on a sheet with a liquid developer comprising:

a tank adapted to contain a liquid developer including marking particles in an electrically insulating carrier liquid;

means for receving a sheet having an electrostatic latent image thereon and for directing the sheet into said tank;

a deflector roll mounted in said tank for receiving the leading edge of the sheet from the first camming means and for lifting the image side of the sheet oil the surface of said first camming means thereby preventing sliding contacting movement between the image side of the sheet and said first camming means, said roll having a tangential velocity the same as the linear velocity of the sheet to prevent relative movement therebetween;

second camming means positioned in said tank in facing relation to the image side of the sheet for receiving the leading edge of the sheet in sliding con tact after it passes said deflector roll and for guiding the sheet upwardly and out of said tank; and

means for receiving the sheet from said second camming means and advancing it upwardly out of said tank, said last named means so arranged that the image side of the sheet is lifted away from the surface of said camming means thereby preventing relative sliding contacting movement between the image side of the sheet and said second camming means, and including a driven roller in engagement with the non-image side of the sheet with a tangential velocity the same as the linear velocity of the sheet, a pressure roller in engagement with the image side of the sheet, and spring means urging said pressure roller toward said driven roller thereby squeezing said sheet therebetween as the sheet moves upwardly out of said tank thereby causing the removal of a substantial portion of said developer carrier liquid and promoting the adhesion of the deposited marking particles thereon.

5. The developer unit as defined in claim 4 further including a scrubber means mounted adjacent to and in sliding contact with said pressure roller for cleaning said roller and for removing any deposits of marking particles therefrom.

6. The developer unit as defined in claim 1 further including roller means positioned to feed a sheet into said channel so that the leading edge thereof contacts said deflector means, and second roller means positioned to receive a sheet from said channel so that the trailing edge of said sheet is in sliding relation with said second camming means.

7. A unit for developing electrostatic images on a sheet with a liquid developer comprising:

means for receiving a sheet having an electrostatic latent image thereon and for directing the sheet into said tank including a driven feed roll in engagement with the non-image side of said sheet, a pressure roll in engagement with the image side of said sheet and spring biasing means urging said pressure roll toward said driven roll thereby causing the pressure roll to rotate with a tangential velocity identical to the linear velocity of said sheet so as not to distort the latent electrostatic image on said sheet;

second camming means positioned in said tank in facing relation to the image side of the sheet for receiving the leading edge of the sheet in sliding contact after it passes said deflector roll and for guiding the sheet upwardly and out of said tank; and

means for receiving the sheet from said second camming means and advancing it upwardly out of said tank, said last named means so arranged that the image side of the sheet is lifted away from the sur face of said second camming means thereby preventing relative sliding contacting movement between the image side of the sheet and said second camming means.

8. The developer unit as defined in claim 1 further including means for agitating the developer to insure an even dispersion of marking particles throughout the electrically insulating liquid carrier.

References Cited UNITED STATES PATENTS 1,810,699 6/ 1931 Diescher 118-429 XR 2,279,166 4/1942 Hudil et al.

3,186,325 6/1965 Belder -89 3,207,050 9/1965 Linberger 118637 XR 3,249,088 5/1966 Ostensen 118-637 FOREIGN PATENTS 1,095,577 12/1954 France.

1,135,294 8/1962 Germany.

CHARLES A. WILLMUTH, Primary Examiner.

PETER FELDMAN, Examiner.