Electrostatographic transfer with artifact suppression

• US 4,914,483 A
• Filed: 04/17/1989
• Issued: 04/03/1990
• Est. Priority Date: 04/17/1989
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Paxon, James F.
• Primary Examiner(s): Grimley, A. T.
• Assistant Examiner(s): Smith, Matthew S.
• Application Number:
  US07/338,812
• Time in Patent Office: 351 Days
• Field of Search: 355/312, 355/309, 355/308, 355/271, 355/277, 355/326, 355/327, 355/273, 355/208
• US Class Current: 399/305
• CPC Class Codes: G03G 15/04 for exposing, i.e. imagewise exposure by optically projecting the original image on a photoconductive recording material
• CPC Class Codes: G03G 15/167 at least one of the recording member or the transfer member being rotatable during the transfer

Abstract

An electrostatographic reproduction apparatus includes an image member for bearing toned electrostatic images, and transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency. The transfer member includes a plurality of vacuum vents for gripping a receiver sheet thereto such that the vents affect the transfer efficiency in the region of the toned images which align with the vents. Means are provided for adjusting the density of the toned image on the image member in the region of the vents such that the affect on the transfer efficiency by the vents is substantially offset by the adjustment to the density of the toned image. In a preferred embodiment, the transfer member is a drum.

Claims

1. An electrostatographic reproduction apparatus comprising:

an image member for bearing toned electrostatic images;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for adjusting the density of the toned image on the image member in said region such that the affect on the transfer efficiency by the gripping means is substantially offset by the adjustment to the density of the toned image.

2. An electrostatographic reproduction apparatus as defined in claim 1 wherein:

said transfer member is a drum; and

said gripping means is a plurality of vacuum vents in the drum.

3. An electrostatographic reproduction apparatus comprising:

an image member for bearing toned electrostatic images;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means negatively affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for increasing the density of the toned image on the image member in said region such that the negative affect on the transfer efficiency by the gripping means is substantially offset by the increase in the density of the toned image.

4. An electrostatographic reproduction apparatus comprising:

an image member for bearing toned electrostatic images;

transfer apparatus having a transfer member for transferring a plurality of related toned images in superimposed relation from the image member to a receiver sheet with a given transfer efficiency to form a composite reproduction, said transfer member including means for gripping a receiver sheet thereto such that the gripping means affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for adjusting the density of the toned images on the image member said region such that the affect on the transfer efficiency by the gripping means is substantially offset by the adjustment to the density of the toned images.

5. An electrostatographic reproduction apparatus and defined in claim 4 wherein said plurality of related toned images are of different colors.

6. An electrostatographic reproduction apparatus comprising:

an image member;

a dot matrix print head for producing an electrostatic charge dot pattern on an image member;

a development station for applying toner to the electrostatic charge dot pattern to form a transferable toner image;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for adjusting the electrostatic charge dot pattern on the image member in the region of the image member which aligns with the gripping means such that the affect on the transfer efficiency by the gripping means is substantially offset by the adjustment to the electrostatic charge dot pattern.

7. An electrostatographic reproduction apparatus comprising:

an image member;

a dot matrix print head for producing an electrostatic charge dot pattern on an image member;

a development station for applying toner to the electrostatic charge dot pattern to form a transferable toner image;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means negatively affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for increasing the electrostatic charge dot pattern on the image member in the region of the image member which aligns with the gripping means such that the affect on the transfer efficiency by the gripping means is substantially offset by the increase in the electrostatic charge dot pattern.

8. An electrostatographic reproduction apparatus comprising:

an image member;

means for producing a single bit per pixel electrostatic charge dot pattern on the image member for reproducing picture signal levels using halftones by grouping several dots to form a superpixel such that halftone density level is a function of the percent dot which fills the area of the superpixel;

a development station for applying toner to the electrostatic charge dot pattern to form a transferable toner image;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for adjusting the percentage dot in the region of the image member which aligns with the gripping means such that the affect on the transfer efficiency by the gripping means is substantially offset by the adjustment to the percentage dot.

9. An electrostatographic reproduction apparatus comprising:

an image member;

means for producing a multiple bit per pixel electrostatic charge dot pattern on an image member by changing the density of each pixel in accordance with a multi-bit word corresponding to the pixel;

a development station for applying toner to the electrostatic charge dot pattern to form a transferable toner image;

transfer apparatus having a transfer member for transferring toned images from the image member to a receiver sheet with a given transfer efficiency, said transfer member including means for gripping a receiver sheet thereto such that the gripping means affects the transfer efficiency in the region of the toned images which align with said gripping means; and

means for adjusting the multi-bit word corresponding to each pixel on the image member in the region of the image member which aligns with the gripping means such that the affect on the transfer efficiency by the gripping means is substantially offset by the adjustment to the multi-bit word.