Vector pinning in an electrophotographic machine

Claim 3

The method of claim 1 wherein the steps of said method are repeated at intervals during the operation of said machine.

Claim 4

The method of claim 1 wherein the reference voltage is obtained by sensing the clean photoconductor within the area of the photoconductor used for document reproductions.

Claim 7

The method of claim 4 wherein the reference voltage is obtained by sensing the clean photoconductor within the area of the photoconductor used for document reproductions.

Claim 8

The method of claim 5 wherein the steps of said method are repeated at intervals during the operation of said machine.

Claim 9

The method of claim 6 wherein the toner density concentration has been checked and found to be within an acceptable predetermined range prior to each occurrence of step 1.

Claim 10

Apparatus for maintaining a white, gray or otherwise shaded or colored vector in an electrophotographic machine where said vector is the value of the image voltage on the photoconductor produced by imaging a single-shaded surface minus the developer bias voltage comprising: a photoconductor; a charge corona for laying down a relatively uniform charge on said photoconductor; an erase lamp means for producing a discharged reference test area in the area of the photoconductor used for document reproductions; a document lamp means for illuminating a single-shaded original for producing a charged test area in the area of the photoconductor used for document reproductions; developing means for toning said charged test area; reflectivity-sensing means for viewing said reference test area and producing a reference voltage therefrom; said reflectivity means also viewing said charged test area and producing a representative image voltage therefrom; first circuit means for comparing said reference and representative image voltages; and second circuit means for adjusting said apparatus for maintaining said vector to maintain the level of said vector within an acceptable predetermined range.

Claim 11

Apparatus for maintaining a white, gray or otherwise shaded or colored vector in an electrophotographic machine where said vector is the value of the image voltage on the photoconductor produced by imaging a single-shaded surface minus the developer bias voltage comprising: a photoconductor; a charge corona for laying down a relatively uniform charge on said photoconductor; an erase lamp means for producing a discharged reference test area in the area of the photoconductor used for document reproductions; a document lamp means for illuminating a single-shaded original for producing a charged test area in the area of the photoconductor used for document reproductions; developing means for toning said charged test area; reflectivity-sensing means for viewing said reference test area and producing a reference voltage therefrom; said reflectivity means also viewing said charged test area and producing a representative image voltage therefrom; first circuit means for comparing said reference and representative image voltages; and second circuit means for adjusting said apparatus for maintaining said vector to maintain the level of said vector within an acceptable predetermined range.

Claim 12

In an electrophotographic machine of the transfer type including a photoconductor, a charge corona for producing a relatively uniform charge on the photoconductor, an exposure station for producing a latent image upon the charged photoconductor, a developer with a supply of toner for applying said toner to the latent image whereby a toned image is produced, a transfer corona station to transfer the developed latent image to a receiving member, a preclean corona and an erase lamp for neutralizing and discharging remaining charge on the photoconductor after transfer, a cleaning station for cleaning away residual toner remaining on the photoconductor after transfer, means for maintaining a single-shaded vector where said vector is the value of the image voltage on the photoconductor produced by imaging a single-shaded surface minus the developer bias voltage, and reflectivity-sensing means for viewing said photoconductor, a special machine test cycle including the steps of: (1) charging the photoconductor; (2) erasing the charge on the photoconductor except for a test area located in the area of the photoconductor used for document reproductions; (3) imaging the photoconductive test area from a single-shaded surface; (4) developing said test area; (5) producing a representative reference voltage by viewing the erased area with said reflectivity-sensing means; (6) producing a representative image voltage by viewing the developed test area with said reflectivity-sensing means; and (7) obtaining a comparison of said representative voltages.

Claim 13

In an electrophotographic machine of the transfer type including a photoconductor, a charge corona for producing a relatively uniform charge on the photoconductor, an exposure station for producing a latent image upon the charged photoconductor, a developer with a supply of toner for applying said toner to the latent image whereby a toned image is produced, a transfer corona station to transfer the developed latent image to a receiving member, a preclean corona and an erase lamp for neutralizing and discharging remaining charge on the photoconductor after transfer, a cleaning station for cleaning away residual toner remaining on the photoconductor after transfer, means for maintaining a single-shaded vector where said vector is the value of the image voltage on the photoconductor produced by imaging a single-shaded surface minus the developer bias voltage, and reflectivity-sensing means for viewing said photoconductor, a special machine test cycle including the steps of: (1) charging the photoconductor; (2) erasing the charge on the photoconductor except for a test area located in the area of the photoconductor used for document reproductions; (3) imaging the photoconductive test area from a single-shaded surface; (4) developing said test area; (5) producing a representative reference voltage by viewing the erased area with said reflectivity-sensing means; (6) producing a representative image voltage by viewing the developed test area with said reflectivity-sensing means; and (7) obtaining a comparison of said representative voltages.

Claim 14

The method of claim 9 wherein said test cycle is run upon the completion of copy production.

Claim 15

The method of claim 10 wherein said test cycle is run during the middle of a single run by interrupting the production of copies in order to make the test cycle.

Claim 16

The method of claim 11 further including the steps of: noting changes in the comparison of said representative voltages from test cycle to test cycle; and adjusting said means for maintaining said single-shaded vector in response to said changes.

Claim 17

The method of claim 9 wherein a toner density concentration check is performed on said test cycle prior to step 1 and toner concentration is found to be within an acceptable predetermined range.

Claim 18

The method of claim 9 wherein said test area and the erased area are produced within the image area used for producing large copies but not used for producing small copies.

Claim 19

The method of claim 14 wherein a toner density concentration check is performed on said test cycle prior to step 1 and toner concentration is found to be within an acceptable predetermined range.