Method and apparatus for preparing liquid tone for direct transfer to the media during electrophotographic printing

• US 5,136,334 A
• Filed: 05/17/1991
• Issued: 08/04/1992
• Est. Priority Date: 05/17/1991
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Hall, James A., Bearss, James G., Camis, Thomas
• Primary Examiner(s): Grimley, A. T.
• Assistant Examiner(s): BARLOW JR, JOHN E
• Application Number:
  US07/701,926
• Time in Patent Office: 445 Days
• Field of Search: 355/245, 355/256, 355/279, 355/326, 355/327, 355/328, 118/659, 118/660, 118/661, 118/644, 118/645
• US Class Current: 399/233
• CPC Class Codes: G03G 15/0157 with special treatment between monocolour image formation
• CPC Class Codes: G03G 15/0163 primary transfer to the final recording medium
• CPC Class Codes: G03G 15/169 with means for preconditioning the toner image before the transfer G03G15/095 and G03G15/11 take precedence

Abstract

Liquid toner conditioning apparatus for use in an electrophotographic color printer and including a stabilizing roller positioned adjacent to the surface of a photoconductive drum and operative for transforming discrete color toner particles on the surface of the drum into a stabilized unitary polymeric film structure which may be directly transferred onto an adjacent print medium. Advantageously, the stabilizing roller will include an inner core member which may be heated as well as connected to a source of either AC bias or DC bias or both. This stabilizing and toner conditioning roller further includes a soft elastomeric roller cover positioned around the periphery of the inner core member and has a smooth outer surface which makes direct contact with the developed toner layers on the surface of the adjacent photoconductive drum.

Claims

1. Electrophotographic color printing apparatus including, in combination:

a. a photoconductive drum,

b. a source of liquid toner adjacent to said photoconductive drum,

c. electrostatic bias means associated with said source of liquid toner for transferring liquid toner layers to the surface of said photoconductive drum,

d. means adjacent to said photoconductive drum for developing images in said toner layers thereon,

e. liquid toner conditioning means positioned in intimate contact with said photoconductive drum for preparing and conditioning developed color liquid toner layers on said drum for direct transfer from the surface of said drum to an adjacent print medium which passes in intimate contact with the surface of said photoconductive drum,

f. said liquid toner conditioning means including means for stabilizing and compressing a toner image on the surface of said photoconductive drum using thermal, electrostatic and mechanical forces,

g. said stabilizing means including a roller member rotatably mounted adjacent to said photoconductive drum and having an inner core member and an outer cover thereon operative to rotate in direct contact with the surface of said photoconductive drum, thereby stabilizing the image on the surface of said drum and preserving its fidelity and preventing it from adhering to said roller while the amount of fluid vehicle carrying said toners is reduced,

h. means for affixing a source of heat adjacent to said inner core member of said stabilizing roller, and

i. means connecting said inner core member of said stabilizing roller to a source of either AC bias or DC bias or both.

2. The apparatus defined in claim 1 wherein said outer cover of said stabilizing roller is a soft elastomeric material.

3. Conditioning and stabilizing apparatus for integrating and converting toners for discrete particle form into a cohesive and unitary polymeric film, including in combination:

a. photoconductive means having an outer surface thereof for receiving successive liquid color toner films,

b. conditioning and stabilizing means positioned in intimate contact with said surface of said photoconductive member, and

c. means within said conditioning and stabilizing means operative for applying a combination of mechanical pressure, electrostatic forces, and thermal energy to said surface of said photoconductive member, whereby said liquid color toners may be compressed into a unitary and cohesive polymeric film with the toner particles therein recharged for subsequent transfer to a selected print medium.

4. The apparatus defined in claim 3 which includes means for connecting said conditioning and stabilizing means to a source of either AC bias or DC bias or both for thereby providing said electrostatic forces to said liquid color toner films.

5. Conditioning and stabilizing apparatus for integrating and converting toners form discrete particle form into a cohesive and unitary polymeric film, including in combination:

a. photoconductive means having an outer surface thereof for receiving successive liquid color toner films thereon,

b. conditioning and stabilizing means positioned in intimate contact with said surface of said photoconductive member and operative for applying a combination of mechanical pressure, electrostatic forces, and thermal energy to said surface of said photoconductive member, whereby said liquid color toners may be compressed into a unitary and cohesive polymeric film with the toner particles therein recharged for subsequent transfer to a selected print medium,

c. said conditioning and stabilizing means comprising a roller apparatus having an inner core member containing a heating element and connected to a source of either AC bias or DC bias or both, and

d. an outer roller member surrounding said inner ore member and operative to be driven against the surface of said photoconductive member.