Walkup v. Greig

• Decision Date: 11 June 1964
• Docket Number: Patent Appeal No. 7053.
• Parties: Lewis E. WALKUP, Appellant, v. Harold G. GREIG, Appellee.
• Court: U.S. Court of Customs and Patent Appeals (CCPA)

52 CCPA 701, 332 F.2d 800 (1964)

Lewis E. WALKUP, Appellant, v. Harold G. GREIG, Appellee.

Patent Appeal No. 7053.

United States Court of Customs and Patent Appeals.

June 11, 1964.

Norman E. Schrader, Rochester, N. Y., W. Houston Kenyon, Jr., New York City (Richard K. Parsell, Kenyon & Kenyon, New York City, of counsel), for appellant.

A. Russinoff, Princeton, N. J., for appellee.

Before WORLEY, Chief Judge, and RICH, MARTIN, SMITH and ALMOND, Judges.

WORLEY, Chief Judge.

Walkup, junior party in Interference No. 89,802, appeals from the decision of the Board of Patent Interferences awarding priority of invention of the eight counts therein to Greig, senior party. Walkup states here that he seeks reversal of the board's decision as to counts 1 to 7, but not count 8. Accordingly the appeal is dismissed as to that count.

Greig is involved on the basis of his patent No. 2,811,465, having a filing date of April 30, 1952, and assigned to Radio Corporation of America, hereafter RCA. The counts correspond to claims of that patent copied in Walkup application Serial No. 401,811, filed January 4, 1954, and owned by the Xerox Corporation, which was formerly the Haloid Company, hereafter Haloid.¹

Greig took no testimony to prove conception and reduction to practice prior to his filing date and thus is restricted to that date. Walkup took testimony and relied on certain activities which took place between August 25 and September 5, 1950, as proving conception and actual reduction to practice.

The counts are directed to a device for use in the reproduction of visual images by the process of xerography. Testimony for Walkup shows that xerography involves the use of a base plate of conductive material coated with a thin layer of photoconductive material which is relatively insulating in darkness and relatively conductive when illuminated. The entire exposed area of the photoconductive coating is first given a uniform electrical charge in the darkness, which charge remains as static electricity. Then a light image of the item to be reproduced is made to fall on the surface of the photoconductive layer with the result that the illuminated areas of the layer become relatively conductive and the charges on those areas pass through the layer to the underlying base plate and discharge to ground. The non-illuminated areas continue to be nonconductive, and the charges there remain in place on the surface of the photoconductive layer. There is thus created on the photoconductive layer a pattern of electrostatic charges corresponding to the applied light image, which pattern is referred to in the counts as a "latent electrostatic charge image."

The latent electrostatic charge image is developed by turning it into a material and visible image. To accomplish that, a finely-divided pigmented electroscopic powder of opposite polarity to the charges on the photoconductive surface is transported into the field of attraction of those charges. The particles, called toner, are attracted to and held on only the charged area of the plate. Subsequently, the toner image is transferred to another surface, as to paper. In another form of xerography, the toner is not applied to the plate bearing the latent image, but is applied directly to a paper web placed on the plate after its exposure, the toner being held on the paper by the electrostatic charges on the plate acting through the paper.

The counts relate to a development device for conveying toner particles into the field of attraction of the latent image to develop a material image from the latent image. In general, the device embodies a cylindrical member having a surface which is capable of retaining toner means received from supply means and is rotated into contact with the image bearing surface. The construction is brought out more specifically by counts 1 and 7 which are representative and read:

"1. A device for applying electroscopic developer material to a record receiving medium bearing a latent electrostatic charge image to be developed, said device comprising a cylindrical member presenting a peripheral surface capable of retaining a quantity of electroscopic material thereon, means for uniformly distributing a quantity of electroscopic developer material on said surface, and means for bringing said surface into contact with the surface of the record receiving medium.

"7. A device for applying electroscopic developer powder to a record receiving medium bearing a latent electrostatic charge image to be developed, said device comprising a cylindrical roller member having a surface provided with a multiplicity of small pits substantially uniformly distributed about said surface, means for applying a quantity of electroscopic developer powder to said roller, said powder being received and held by an electrostatic attractive force in said pits, and means for passing the record receiving medium into intimate rolling contact with said roller member whereby to transfer, through electrostatic attraction greater than said first mentioned attractive force, portions of said developer powder from said roller onto selected areas of said record receiving member corresponding to said charge image."

In 1950, Battelle Memorial Institute was conducting research on xerography under the sponsorship of Haloid. The work was carried on in the Graphic Arts Division of Battelle under the direction of one William T. Reid, and Walkup was Assistant Supervisor of that Division in charge of the work done on xerography.

Prior to August and September of 1950, Walkup had been active in work on a technique of xerographic development known as "cascade." He describes cascade development as employing a mixture of small dust-like particles of toner, which it is desired to deposit in charged image areas, and larger bead or marble-like particles called "carrier," which are predominately of spherical shape. The mixture tumbles or slides across a sloping image-bearing plate under the influence of gravity. The particles and toner have such properties, described as "tribo-electrical" relationship, that the toner particles will have a polarity causing them to detach themselves from the carrier particles in charged portions of the image-bearing articles and be attracted to the photoconductive surface.

For conception of the different type of development of the invention in issue, referred to as brush development, Walkup relies on a June 14, 1950 entry in his laboratory notebook which reads:

"It has been known an sic used that a granular material can be used as a vehicle for developer powder both in the development and the cleaning of a xerographic plate. If a lot of developer powder is mixed with the larger granular material then the resulting mixture is rich in powder and if it is cascaded over a plate carrying an electrostatic image some of its powder will be given to the image and the image `developed\'. If, on the other hand, there is little or no powder mixed with the granular material it will be poor or "lean" in powder. If the granular material is cascaded over the plate it will take powder off of the plate. This removal of the powder from the plate is used in cleaning the residual image off of the plate.

"The basically new idea suggested here consists in substituting fine fibers, as of a brush or fur, for the granular material. In this capacity, the fibers of the brush should work in a manner similar to action of the granular cleaner. Thus a soft brush should clean a plate, and a brush loaded with powder should `develop\' a plate. For either use the brush or fiber element may take a number of physical forms of which a cylinder with the fibers extending out approximately radially is typical and perhaps desirable. Departures from the radial direction may be desirable so that the fiber touches the plate as a line rather than as a point.

* * * * * *

"In using the brush as a developer powder will have to be added to the brush as it is used up. A simple means of placing powder on the brush might be to have the brush pass over and rub against a mass of developer powder."

In August 1950, one Carlton was working on an assignment by Walkup to build and test apparatus for determining the feasibility of using a rotary brush for cleaning xerographic plates which had become dirty in use. Carlton interrupted that work, from August 25 to September 5, 1950, to build and test the brush type development machine relied on here by Walkup as a reduction to practice. The development machine was made by modifying the brush-type cleaning machine, using the same brush comprising fur wrapped around a wooden cylinder.

The most nearly contemporaneous record of the August-September experiments as noted by the board, is that set out in an entry made by Carlton in his notebook under date of October 13, 1950. There Carlton illustrates a rotatably-mounted cylindrical brush underlying an advancing plate and contacting the under side of the plate with movement opposite to the direction of the plate. The portion of the brush diametrically opposite the plate contacts the upper surface of a body of material in a container with an open top, which container is labeled "Powder." Carlton's description of that apparatus and its operation follows:

"* * * a preliminary trial of fur development was made because it may be more practical to use with a continuous xerographic process, and possibly it may be simpler for all xerographic development. Good images were developed with the fur but they were not as dense as those developed by the cascade method.

* * * * * *

"The fur is mounted on a wooden cylinder which rotates slowly while the plate passes over it. The fur speed is variable from 110 RPM to 440 RPM. The brush is 3 in. in diameter. The plate is pushed through by hand. The distance between the plate and the brush is determined by the height of guide bars above the fur. This distance is changed by placing spacers under the guide bars. The wooden

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