In re East

495 F.2d 1361, 181 U.S.P.Q. (BNA) 716, 1974 CCPA LEXIS 169
CourtCourt of Customs and Patent Appeals
DecidedMay 9, 1974
DocketPatent Appeal No. 9140
StatusPublished
Cited by4 cases

This text of 495 F.2d 1361 (In re East) is published on Counsel Stack Legal Research, covering Court of Customs and Patent Appeals primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
In re East, 495 F.2d 1361, 181 U.S.P.Q. (BNA) 716, 1974 CCPA LEXIS 169 (ccpa 1974).

Opinion

LANE, Judge.

This appeal is from the decision of the Patent Office Board of Appeals affirming the rejection of claims 11-13 of application serial No. 724,313, filed April 1, 1968, entitled “Developer Mixes.” The application is for reissue of appellants’ U.S. Patent No. 3,320,169, issued on May 16, 1967.1 Reissue claims 1-10 (identical to original claims 1-10) stand allowed. We affirm.

The Invention Described In The Patent

The invention described in the patent relates to electrophotographic processes for producing visible images and specifically to developer mixes for use in such processes. The specification describes these developer mixes in the following passage, which we designate [A]:

The developer mixes of this invention are three component mixtures consisting essentially of (1) magnetic carrier particles, (2) toner particles haveing a particle size smaller than the particle size of the magnetic carrier particles, the toner particles consisting essentially of a discrete mixture of pigmented resin particles having the necessary triboelectric relationship to the magnetic carrier particles so that upon admixture the toner particles acquire a charge of the desired polarity to develop the image, and (3) an aliphatic acid having from 10 to 26 carbon atoms and/or a salt of such aliphatic acid, the cation of the salt being calcium, barium, sodium, lithium, magnesium, manganese, zinc, nickel, iron, cobalt, lead or ammonium. A mixture of any two or more of these aliphatic acids and/or salts can be used. For convenience and brevity the expression “additive” will be used herein to refer to such aliphatic acid, salt thereof or mixture of such salts, or mixture of such acids, or mixture of such salts and such acids, [emphasis ours]

The specification of the patent also contains a passage which we designate [B]:

The exact explanation of why the fatty acids and the salts thereof, herein disclosed, are effective to correct the problems of prior known developer mixes is not fully understood. The improvement in print density, reduced background and minimization of mix deterioration is believed to be due in part at least to the additive affecting the triboelectric relationship between the carrier and the toner. The additive tends to maintain a proper triboe-lectric charge balance between the [1363]*1363toner and the magnetic carrier particles so that the attraction between the latter and the toner does not override the attractive force of the charged areas of the electrostatic recording member for the toner. In reversal printing, this balance permits the proper repulsion of the toner to effect adherence thereof to the areas of the print to which the developer powder should be applied. In positive printing, this balance enables the charged image areas to attract and hold the toner.
Moreover, the presence of the additive tends to improve the mobility of the components of the developer mixes resulting in better mixing or distribution of the toner relative to the carrier particles, particularly when fresh toner is introduced into the developer mix. With the developer mixes of this invention, the introduction of fresh toner along with additive in proportions of from 0.02 to 0.4 part by weight of additive per 100 parts by weight of carrier in the case of the reversal developer mix, and from 0.02 to 0.1 part by weight of additive per 100 parts by weight of carrier in the ease of positive mix results in the more complete and uniform distribution of the fresh toner throughout the developer mix upon subjecting the mixture to agitation or mixing. Such mixing is conventional in the operation of electrostatic printing machines, [emphasis ours]

The patent contains eleven examples of specific developer mixes. In each example, the “carrier” is described as “powdered iron,” but the specification also states that: [C]

The magnetic particles can be iron, ferrites, nickel, cobalt, or other magnetic particles having an average particle size of from 25 to 500 microns, preferably 25 to 150 microns, and always larger than that of the toner particles. For reversal developer mixes, the magnetic particles and the toner particles are chosen to have a triboelectric relationship such as to produce a negative charge on the toner particles when the two are mixed. For positive developer mixes, the magnetic particles and toner particles are chosen to have a triboelectric relationship such as to produce a positive charge on the toner particles when the two are mixed.

Appearing in the initial portion of the specification are two paragraphs each describing a different technique for applying developer mixes. One paragraph, which we designate [D], describes the “magnetic brush” technique:

One known technique of applying such reversal and positive developer mixes is the so-called magnetic brush technique involving the use of a mixture of larger magnetic particles, usually iron, and smaller toner or powder particles constituted of pigmented resin and the application of this developer mix by means of a cylindrical magnetic applicator roller on the periphery of which the magnetic brush is formed and reformed during the rotation of the applicator roller to maintain enough toner in the so-called brush for proper development of the image. The image bearing member, usually paper, is passed in substantially tangential contact with this brush with the side to be developed in contact or near contact with the brush and the opposite side, herein térmed the back, positioned remote from the magnetic brush. Such type of developer is disclosed, for example, in the Paul B. Streich, Sr., United States Patent No. 3,003,462 granted October 10, 1961.

The other paragraph, which we designate [E], describes the “cascade” technique :

Another technique of developing electrostatic latent images involves the application of developer mixes by cascading said mixture over the charged surface. The electroseopic powder which adheres to the carrier particles is attracted by the imaged portions of the electrophotographic member adhering thereto as the carrier particles flow over the image.

[1364]*1364The patent contains ten claims. Claim 1 is representative:

1. A developer mix for developing electrostatic latent images on photo-conductive insulating material employing a magnetic brush for applying the developer to the latent images, which developer mix consists essentially of magnetic carrier particles and toner particles having a particle size smaller than the particle size of the magnetic carrier particles, the toner particles consisting essentially of a pigmented thermoplastic resin having a resistivity less than 10 19 ohm-cm, and a particle size of from 1 to 75 microns, said toner particles being mixed with the magnetic carrier particles having a particle size of from 25 to 150 microns in the proportions of from 10 to 100 parts of magnetic carrier particles per part of toner particles by weight, and said developer mix containing from 0.02 to 0.4 part by weight of a third component per 100 parts by weight of carrier particles, said third component intimately mixed with and forming a coating on the exterior of said magnetic carrier particles

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Bluebook (online)
495 F.2d 1361, 181 U.S.P.Q. (BNA) 716, 1974 CCPA LEXIS 169, Counsel Stack Legal Research, https://law.counselstack.com/opinion/in-re-east-ccpa-1974.