US3869910A

US3869910A - Diagnostic test device for developer materials

Info

Publication number: US3869910A
Application number: US371331A
Authority: US
Inventors: Joseph Louis Scaletta
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1973-06-18
Filing date: 1973-06-18
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11
Also published as: JPS5043937A; FR2233625A1; FR2233625B1; NL7403910A; CA1006012A; DE2412978A1

Abstract

A method and apparatus is provided to test samples of developer material comprising carrier and toner particles. The apparatus has a hopper into which a sample of developer is placed. A gate is opened to allow the developer to flow from the hopper over at least a conductive surface and two conductive pads located below the conductive surface to develop the same. A development electrode plate is spaced from the conductive pads to enhance solid area development. After development, the electrode plate is removed from the apparatus to expose the conductive pads and the optical density of toner development of the conductive pads is analyzed to determine developer quality. This apparatus is portable and may be used by a service representative to test developer on machine location.

Description

United States Patent Scaletta Mar. 11, 1975 DIAGNOSTIC TEST DEVICE FOR DEVELOPER MATERIALS OTHER PUBLICATIONS Brickmore, J. T., et al., Configural Studies on Cascade lnvemorl J p Louis Scaletla, ROChSter, Development, in Photographic Science & Engineer- N.Y. ing, 14 (1): p. 42-51, Jan-Feb. 1970. 73 A X C t' t f d, 1 Sslgnee 32: orpora S am or Primary Examiner-Richard C. Quelsser Assistant Examiner-Joseph W. Roskos [22] Filed: June 18, 1973 ABSTRACT [21 Appl. No.2 371 331 [571 A method and apparatus is provided to test samples of developer material comprising carrier and toner parti- [52] [1.8. CI 73/150 R, 118/9, 356/202, c1es The apparatus has a hop er into which a Sample of developer is placed. A gate is opened to allow the [51] Int. Cl. Gtlln 33/32 developer to flow from the hopper Over at least a Com [58] Flew of 73/150 ductive surface and two conductive pads located 356/209 1 118/9, 324/32 below the conductive surface to develop the same. A

development electrode plate is spaced from the con- [56] References cued ductive pads to enhance solid area development. After U T STATES PATENTS development, the electrode plate is removed from the 2,573,881 11/1951 Walkup et a1 96/1 SD UX apparatus to expose the conductive pads and the opti- 2,972,332 2/1961 Limberger 96/1 SD UX cal density of toner development of the conductive .05 2 /1962 ,,1werks 96/1 SD UX pads is analyzed to determine developer quality. This g if apparatus is portable and may be used by a service o e 3,719,165 3/1973 Trachienberg et al 118/9 x representat've to test developef on fnachme locat'on' 3,756,192 9/1973 Locklar et a1. 118/9 X 15 Claims, 3 Drawing Figures "Illii iii l 42 VOLTAGE 54 SUPPLY PATENTIED 3369,5110

snznujz PATENIEUHARI 1 ms sum 2 or g and DIAGNOSTIC TEST DEVICE FOR DEVELOPER MATERIALS DESCRIPTION OF THE INVENTION A problem with many electrostatic copying machines is that at times, the resultant copy is either light density, overtoned, or has high background. When a machine is serviced, the service representative is presented with a problem of determining whether the above is due to poor developer or to some other malfunction in the copier. It would be very helpful if the service representative had a tool by which he could determine the developer quality at the machine location.

Accordingly, it is an object of this invention to pro vide an apparatus for testing developer material to de termine the quality thereof at the machine location.

A further object of this invention is to provide an apparatus for obtaining certain information on developer materials, which information, when analyzed can be useful in predicting developer performance.

Other objects of this invention will become more apparent from the following description with reference to the drawings wherein:

FIG. 1 is a view of a developer test apparatus;

FIG. 2 is a view taken along section .line 22 of FIG. 1; and

FIG. 3 is a schematic of an electrical circuit for the test apparatus.

Referring to the drawings, there is illustrated a developer testing apparatus having a main support frame comprising a bottom wall and a pair of spaced sidewalls 12 secured to the bottom wall at the opposite sides thereof. A shoulder 14 extends inwardly from each sidewall. A testboard 16 of insulating material is located between the sidewalls 12 with the rear face thereof bearing against the shoulders 14. A thin conductive metal film such as copper is secured to the top face of the testboard l6. Screws 18 fasten the testboard to the shoulders 14. The upper portion 20 of the front edge of each wall 12 slants inwards and downwards from the upper edge and meets with a lower edge 22 of the front wall which slants forwards and backwards from the line of juncture therebetween. A plate 24 is secured to the upper edge 20 of each wall by screws 26 (only one shown). The plate 24, the upper portion of the testboard l6 and the upper portion 20 of the walls 12 form a developer hopper at the upper portion of the testing apparatus. The lower edge 28 of the plate 24 is spaced a certain distance from the testboard 16 to form a developer hopper orifice therebetween. A slidable gate member 30 is secured to the plate 24 by a pair of laterally spaced bolts 32 (only one shown) which extend through slots 33 in the gate 30 into the plate 24. A washer 34 is slidably mounted on the bolt 32 and the washer 34 to bias the washer into engagement with the plate 30 and thereby urge the plate 30 into slidable engagement with the plate 24. The slots 33 in the plate 30 extend in a longitudinal direction allowing the gate to be moved downwards to bring the bottom edge 37 thereof into engagement with the testboard 16 to close the hopper orifice or to be moved upwards and withdraw the bottom edge 38 of the gate from the testboard to open the orifice.

Located below the conductive film 17 on the testboard 16 are

conductive pads

33, 40, 42 and 44, which may comprise copper, electrically insulated from each other and the film 17. The pads are located a sufficient distance below the orifice that a uniform coating of toner particles is deposited on each pad. This distance will vary with the size of the developer, the angle of the testboard and the flow rate. The developable area of each pad is significantly smaller than that of the conductive film 17. As illustrated in FIG. 1, the conductive film 17 has laterally spaced extensions 17a which on compass the conductive pads. These extensions are desirable in some instances but are not necessary to the operation of the apparatus. A development electrode plate 46 bears against and is removably secured to the slanted lower edge 22 of the walls 13 by bolts 48 which extend through a respective slot 50 in the development electrode plate 46 into a respective wall 12. The slots 50 are enlarged at the lower portion thereof so that the head of the bolts 48 can extend therethrough and the upper portion of the slots 50 are smaller so the plate will be held onto the walls by the enlarged heads of the bolts 48. The electrode plate 46 may be removed from the wall 12 by sliding the same upwards until the enlarged bottom portion of the slots 50 are aligned with the heads of the bolts 48 and then tilting the bottom of the plate away from the walls 12 to clear the lower bolts and then lifting the plate away from the walls 12. A voltage supply 51 is locatedbehind the testboard l6 and has terminals electrically connected to each pad, the conductive film and the electrode plate 46 for applying required voltage potentials to each.

The conductive film 17 on the testboard is spaced a given distance from the front edge 22 of the wall 12 that when the rear face of the development electrode plate 46 rests on the front edge 22 there will be a given space therebetween. The wall 12 may berof conductive material and electrically connected to the electrode plate 46 if the voltage potential of both is desired to be at the same level or the electrode plate 46 can be electrically insulated from the walls 12 if different voltage potentials are desired. A recess 52 is provided in the bottom wall 10 for slidably receiving a developer receptacle 54 therein. I

In this apparatus, it is contemplated that there will be at least two

conductive pads

38 and 40. The two pads, the conductive film 17 and the electrode plate 46 are each connected to voltage potentials with the potentials on the pads being different from each other and from the potential applied to the conductive film 17 which is usually ground. The potential applied to the electrode plate 46 will normally be the same as the potential applied to the conductive film but may be a potential which is different than any of the potentials for the pads or the conductive film. As developer passes over the conductive film and pads, toner particles will develop thereonto in accordance with the voltage potentials applied. The voltage potentials are selected in increments relative to each other to set up electric fields so the density of toner developed on each pad and conductive film will be optically different as measured by any standard densitometer in reflectance or transmittance optical density units. The testboard 16 is located at an angle with the horizontal base or bottom wall 10 which optimizes the relative optical developed densities. Depending upon the relative voltage potentials of the various pads, the conductive film and the electrode plate, and the condition of the developer, toner particles may develop onto the electrode plate in accordance with the fields set up between the conductive film and the electrode plate and between the pads and the electrode plate. The applied voltage potentials may be either negative or positive depending upon the information desired and the charge polarity of the toner particles.

In operation, a given quantity of developer, for instance cc., having carrier particles of an average diameter of 100 microns and negatively charged toner particles having an average diameter of 10 microns is placed into the hopper with the hopper gate in closed position. For this size developer, the spacing between the bottom edge 28 of the orifice plate 20 and the testboard 16 is 0.030 inch in gate open position and the spacing between the rear surface of the development electrode plate 46 and the film 17 of the testboard 16 is 0.060 inch. The testboard is at an angle of 50 to the base wall 10. The distance between the orifice and the upper edge of the

pads

38, 40, 42 and 44 is 2 inches. Referring to the schematic electrical circuit shown in FIG. 3, the power supply 51 is designed so that a volt age potential V1 applied to pad 38 is 25 volts, the voltage potential V2 applied to pad 40 is +100 volts, the voltage potential V3 applied to pad 42 is -120 volts, and the voltage potential V4 applied to pad 44 is +50 volts. The conductive film 17 and the development electrode plate 46 are connected to the ground or reference potential thereby creating a field between the development electrode and each

conductive pad

38, 40, 42 and 44 to enhance solid area development. The same field potentials between the

pads

38, 40, 42 and 44 and the electrode plate 46 may be achieved by placing the conductive film 17 at reference or ground potential, electrode plate 46 at +200 volts, pad 38 at +175 volts, pad 40 at +300 volts, pad 42 at +80 volts and pad 44 at +250 volts. Any suitable or conventional voltage supply may be utilized.

The gate 30 is opened and developer from the hopper flows through the hopper orifice by gravity over the testboard and over the conductive sections thereon to develop the conductive sections with toner particles. The residual developer flows into the receptacle 54. When all of the developer has passed from the hopper, the power supply is cut off and the electrode plate 46 is removed from the testing apparatus thereby exposing the testboard 16 with the developed conductive portions. The operator takes a generally transparent tape and places it against the conductive portions to remove the toner particles therefrom and places it on a white sheet of paper in order to see the density of the developed portions. After the test is completed, the receptacle 54 may be removed from the apparatus and the developer discharged therefrom.

The toner particles which are attracted to positive

biased pads

40 and 44 are negative charged toner particles a majority of which would be attracted to a positive charged latent image area on a photoconductor. The toner particles which are attracted to negative

biased pads

38 and 42 are positive charged toner particles which do not develop a positive charged latent image and which may deposit on background areas. The relative development of these pads change as the carrier particles age and therefore this type of information can be useful in determining developer characteristics at various stages during the life thereof. Toner particles will also develop on areas on the electrode plate opposite the pads in the opposite manner with negative charged particles developing on areas opposite

pads

38 and 42 and positive charged particles developing on areas opposite

pads

40 and 44. Toner particles will also be deposited on the conductive film l7 and the area on the electrode plate 46 opposite the film 17. The development pattern of toner on the conductive film 17 and the electrode plate may also be useful at times.

The information gathered can then be used as a standard to guide a service representative when using the test apparatus at a copying machine location when he goes into an office to service a machine which exhibits characteristics that may be attributable to developer problems. He takes the developer from the machine dcveloper sump and puts it through the test apparatus by employing the same procedure hereinbefore described. The service representative compares the density of the developed portions to standard samples to determine developer quality. If the quality does not meet specifications, he can change or modify the developer. If the quality is acceptable, he knows the problem resides elsewhere in the copying system.

This test apparatus may be utilized for obtaining information which is also useful for many purposes. Of course, the number of pads used and the voltage potentials selected will be determined by the purpose for which the information is desired. The size of this apparatus is such that it is easily portable. For instance, it is contemplated that the size be not larger than about 6 inches high by 6 inches long by 3 inches wide.

What is claimed is:

1. An apparatus for testing developer quality comprising: a support structure; a generally flat testboard carried by said support structure at an angle to horizontal; said testboard comprising a conductive surface and at least two conductive pads each electrically insulated from the other and from said conductive surface, an electrode plate carried by said support means spaced from said testboard and located opposite at least a portion of said conductive surface and said conductive pads; means for simultaneously applying different electrical field potentials between said electrode plate and each of said conductive pads and said conductive surface whereby developer may flow through the space between said electrode plate and said testboard to develop said conductive surface and said conductive pads in accordance with said field potentials.

2. The apparatus as recited in claim 1 wherein the field potential between said electrode plate and said conductive surface is substantially zero.

3. The apparatus as recited in claim 1 wherein there is a substantial field between said electrode plate and said conductive surface.

4. The apparatus as recited in claim 1 wherein the field potential between said electrode plate and one of said conductive pads is negative in the direction of said one pad and the field potential between said electrode plate and the other of said conductive pads is positive in the direction of said other pad.

5. The apparatus as recited in claim 4 wherein said conductive surface is electrically connected to ground potential.

6. The apparatus as recited in claim 5 wherein said electrode plate is electrically connected to ground potential.

7. The apparatus as recited in claim 1 wherein said field potentials are such as to develop developer on the conductive pads and conductive surface at relative densities which are optically different from each other as determined by densitometer measurement in optical density units.

8. The apparatus as recited in claim 1 further comprising: a developer hopper located at the upper portion of said support structure, an orifice communicating said hopper with the space between said testboard and said electrode plate, said testboard sloping downwards from said orifice.

9. The apparatus as recited in claim 8 further comprising: movable gate means for closing said orifice, means to retain developer in said hopper and for opening said orifice means to allow developer to flow through said orifice means into the space between said electrode plate and said testboard.

10. The apparatus as recited in claim 8 wherein said conductive surface is located above said conductive pads and has a larger developable area than either of said pads.

11. The apparatus as recited in claim 8 wherein said conductive pads are located below said orifice at a distance to provide generally uniform development thereon.

12. The apparatus as recited in claim 11 wherein the field potential between said electrode plate and one of said conductive pads is negative in the direction of said one pad and the field potential between said electrode plate and the other of said conductive pads is positive in the direction of said other pad.

13. The apparatus as recited in claim 12 wherein said conductive surface is electrically connected to ground potential.

14. The apparatus as recited in claim 13 wherein said electrode plate is electrically connected to ground potential.

15. A method for testing developer comprising: measuring a given amount of developer comprising toner particles and carrier particles into a developer hopper. maintaining a different electrical field potential between an electrode plate and at least two conductive pads and a conductive surface each of which are electrically insulated from each other, passing the developer by gravity at a controlled rate between the electrode plate and the conductive pads and conductive surface to develop the conductive pads and conductive surface with toner particles, and subjecting said pads to toner density analysis.