Method of replenishing developer in a hybrid scavengeless development system

• US 6,248,496 B1
• Filed: 03/07/2000
• Issued: 06/19/2001
• Est. Priority Date: 03/07/2000
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Hollenbaugh, William H. Jr., Stamp, Amy L., Silence, Scott M., Angra, Padam K., Galloway, Merrilee A.
• Primary Examiner(s): GOODROW, JOHN L
• Application Number:
  US09/520,361
• Time in Patent Office: 469 Days
• Field of Search: 399/30, 399/62, 430/137
• US Class Current: 430/111.35
• CPC Class Codes: G03G 13/09 using magnetic brush
• CPC Class Codes: G03G 2215/0621 powder cloud
• CPC Class Codes: G03G 2215/0643 Electrodes in developing area, e.g. wires, not belonging to the main donor part

Abstract

A replenisher material of toner particles and carrier particles, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher is determined as a function of at least one property of the developer and at least one operational property of an apparatus for developing an electrostatic latent image recorded on an image receiving member, and wherein the apparatus includes a housing defining a chamber having a supply of developer comprised of toner particles and carrier particles therein, a donor member spaced from the image receiving member and adapted to transport toner particles of the developer from the chamber to a development zone adjacent the image receiving member, at least one wire positioned in the development zone between the image receiving member and the donor member, a voltage supply for electrically biasing the at least one wire during a developing operation with a current to detach toner particles from the donor member, forming a cloud of toner particles in the development zone, and developing the latent image with toner particles from the cloud, and at least one dispenser for dispensing replenisher comprised of toner particles and carrier particles into the chamber, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher is determined as a function of at least one property of the developer and at least one operational property of the apparatus. The replenisher ratio is preferably determined as a function of the tribo stability of the developer in a non-replenishment mode of the apparatus and/or as a function of the conductivity of the developer in a non-replenishment mode of the apparatus.

Claims

1. A replenisher material comprised of toner particles and carrier particles, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher material is determined as a function of at least one property of a developer and at least one corresponding minimum operational property of an apparatus for developing an electrostatic latent image recorded on an image receiving medium with the developer, and wherein the apparatus comprises:

a housing defining a chamber having a supply of developer comprised of toner particles and carrier particles therein,

a donor member spaced from the image receiving member and adapted to transport toner particles of the developer from the chamber to a development zone adjacent the image receiving member,

at least one wire positioned in the development zone between the image receiving member and the donor member,

a voltage supply for electrically biasing the at least one wire during a developing operation with a current to detach toner particles from the donor member, forming a cloud of toner particles in the development zone, and developing the latent image with toner particles from the cloud, and

at least one dispenser for dispensing replenisher material into the chamber.

2. The replenisher according to claim 1, wherein the replenisher ratio is determined as a function of the tribo stability of the developer in a non-replenishment mode of the apparatus.

3. The replenisher according to claim 2, wherein the tribo stability of the developer is specified in terms of the replenisher ratio required in order to meet a minimum A_T value of the apparatus according to the equation

4. The replenisher according to claim 3, wherein the minimum A_T level of the apparatus ranges from 140 to 165 μ

C/g times % toner.

5. The replenisher according to claim 3, wherein the exponential decay constant in the non-replenishment mode is derived from data on A_T decay over time for different replenisher ratios.

6. The replenisher according to claim 1, wherein the replenisher ratio ranges from 2:

1 to 8;

1 parts by weight.

7. The replenisher according to claim 1, wherein the replenisher ratio is about 3:

1 parts by weight.

8. The replenisher according to claim 2, wherein the replenisher ratio is further determined as a function of the conductivity of the developer in a non-replenishment mode of the apparatus.

9. The replenisher according to claim 8, wherein the conductivity of the developer is specified in terms of the replenisher ratio required in order to meet a minimum σ

value of the apparatus according to the equation

10. The replenisher according to claim 8, wherein the replenisher ratio is determined to be a greater ratio of the replenisher ratio determined as a function of the minimum A_T level and the replenisher ratio determined as a function of the minimum conductivity level, which greater ratio is the replenisher ratio which contains the greater amount of carrier dispensed for a given amount of toner.

11. The replenisher according to claim 1, wherein the toner particles comprise a propoxylated bisphenol A fumarate resin and the toner resin has an overall gel content of from about 2 to about 9 weight percent by weight of the binder, wherein the colorant is carbon black, magnetite, or mixtures thereof, cyan, magenta, yellow, blue, green, red, orange, violet or brown, or mixtures thereof, and one or more external additives of one or more silicon dioxide powder, a metal oxide powder or a lubricating agent, and wherein the carrier particles comprise a steel core coated with polymethyl methacrylate at a coating weight of from 0.5 to 1.3% by weight of a total carrier particle weight.

12. The replenisher according to claim 11, wherein the metal oxide powder is titanium dioxide or aluminum oxide and the lubricating agent is zinc stearate.

13. The replenisher according to claim 1, wherein following triboelectric contact with the carrier particles, the toner particles have a charge per particle diameter (Q/D) of from −

0.1 to −

1.0 fC/μ

m with a variation during development of from 0 to 0.25 fC/μ

m and the distribution is substantially unimodal and possesses a peak width of less than 0.5 fC/μ

m, preferably less than 0.3 fC/μ

m and a triboelectric charge of from −

25 to −

70 μ

C/g with a variation during development of from 0 to 15μ

C/g.

14. A method of setting a replenisher ratio for a replenisher comprised of toner particles and carrier particles to be added to an image developing apparatus, the method comprising determining the replenisher ratio of the toner particles to the carrier particles in the replenisher as a function of at least one property of a developer for the apparatus and at least one operational property of the apparatus.

15. The method according to claim 14, wherein the determining determines the replenisher ratio as a function of the tribo stability of the developer in a non-replenishment mode of the apparatus.

16. The method according to claim 15, wherein the tribo stability of the developer is specified in terms of the replenisher rate (R) required in order to meet a minimum A_T value of the apparatus according to the equation

17. The method according to claim 16, wherein the minimum A_T level of the apparatus ranges from 140 to 165 μ

C/g times % toner.

18. The method according to claim 16, wherein the exponential decay constant in the non-replenishment mode is derived from data on A_T decay over time for different replenisher ratios.

19. The method according to claim 14, wherein the replenisher ratio ranges from 2:

1 to 8;

1.

20. The method according to claim 14, wherein the replenisher ratio is about 3:

1.

21. The method according to claim 15, wherein the method further comprises determining a second replenisher ratio as a function of the conductivity of the developer in a non-replenishment mode of the apparatus.

22. The method according to claim 21, wherein the conductivity of the developer is specified in terms of the replenisher ratio required in order to meet a minimum σ

value of the apparatus according to the equation

23. The method according to claim 21, wherein the determining further comprises determining the replenisher ratio to be a greater ratio of the replenisher ratio determined as a function of the minimum A_T level and the replenisher ratio determined as a function of the minimum conductivity level, which greater ratio is the replenisher ratio which contains the greater amount of carrier dispensed for a given amount of toner.

24. An apparatus for developing an electrostatic latent image recorded on an image receiving member comprising:

a housing defining a chamber having a supply of developer comprised of toner particles and carrier particles therein,

a donor member spaced from the image receiving member and adapted to transport toner particles of the developer from the chamber to a development zone adjacent the image receiving member,

at least one wire positioned in the development zone between the image receiving member and the donor member,

a voltage supply for electrically biasing the at least one wire during a developing operation with a current to detach toner particles from the donor member, forming a cloud of toner particles in the development zone, and developing the latent image with toner particles from the cloud, and

at least one dispenser for dispensing replenisher comprised of toner particles and carrier particles into the chamber, wherein a replenisher ratio of the toner particles to the carrier particles in the replenisher is determined as a fimction of at least one property of the developer and at least one corresponding minimun operational property of the apparatus.