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APPARATUS FOR PRINTING BLACK AND PLURAL HIGHLIGHT COLOR IMAGES IN A SINGLE PASS

IP.com Disclosure Number: IPCOM000025718D
Original Publication Date: 1987-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 188K

Publishing Venue

Xerox Disclosure Journal

Abstract

The method and ap aratus for rendering latent electrostatic ima es on a and more particularly to printing toner images in black and at least two highlighting colors in a single pass of the imaging surface through the processing areas of the printing apparatus. Two of the toners are attracted to only one charge level on a charge retentive surface to thereby provide black and one highlight color while two toners are attracted to another charge level to form the second highlight color.

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XEROX DISCLOSURE JOURNAL

APPARATUS FOR PRINTING BLACK AND PLURAL HIGHLIGHT COLOR IMAGES IN A SINGLE PASS
Howard M. Stark

Proposed Classification

US. C1.430/45

Int. C1. G03g 13/01

The method and ap aratus for rendering latent electrostatic ima es on a

and more particularly to printing toner images in black and at least two highlighting colors in a single pass of the imaging surface through the processing areas of the printing apparatus. Two of the toners are attracted to only one charge level on a charge retentive surface to thereby provide black and one highlight color while two toners are attracted to another charge level to form the second highlight color.

charge retentive sur

P ace visible using multiple colors of dry toner or f eveloper

The charge retentive surface which is initially charged to a voltage Vbiack (approximately. -1000 volts), is discharged to V, (ap roximately. -700 volts) imagewise in the background (white) image areas anato Vd (approximately. - 350 volts) and Va (approximately. - 100 volts) in the highlight (i.e. color other than black) image areas. At development station C, a magnetic brush development system, indicated generally by the reference numeral 30 advances developer materials into contact with the electrostatic latent images. The development system 30 comprises first, second and third developer housings 32, 33 and 34. Preferably, each of the magnetic brush

Volume 12 Number 3 May/June 1987 163

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APPARATUS FOR PRINTING BLACK AND PLURAL HIGHLIGHT COLOR IMAGES IN A SINGLE PASS (Cont'd)

development housings includes two magnetic brush developer rollers 36 and
38. These rollers advance their respective developer materials into contact with the latent image. Each developer roller pair forms a brush comprising toner particles which are attracted by the latent images on the photoreceptor.

By way of example, one of the three developer housings contains positively charged black toner 40 and the other two contain negatively charged magenta and cyan toners 41 and 42. The charge retentive surface containing the images is moved past these housings in a single pass. Color discrimination in the development of the electrostatic latent image is achieved by electrically biasing the three housings 32,33 and 34 to suitable voltages for effecting the attraction of the desired toners to the different potentials on the charge retentive surface. Thus, the housings 32. 33 and 34 may be biased respectively to minus 800,300 and 600 volts, the biasing being provided by dc voltage sources Vb, Vcl and Vc2.

In the preferred embodiment of the invention as disclosed in Figure 1, the housing 32 contains black developer havin triboelectric roperties (i.e.

the latent images by the electrostatic field established between the Vblack charged areas of the photoreceptor and the voltage level of the bias Vb on the developer housing. The housing 33 contains magenta developer tha...