Color image printing apparatus

Details Color image printing apparatus Color image printing apparatus

2000-05-23

2001-05-22

Grimley, Arthur T. (Department: 2852)

Electrophotography

Control of electrophotography process

Control of developing

C399S058000, C358S515000, C358S516000

Reexamination Certificate

active

06236817

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color image printing apparatus, and more particularly, to a color image printing apparatus for processing original color image data using less developer to reproduce the received original color image information on a recording medium.
2. Description of the Related Art
A color image printing apparatus such as a photocopier, a printer or a facsimile machine prints an image corresponding to received original color image data on a recording medium such as a sheet of paper. The color image printing apparatus reproduces color corresponding to the original image data on a recording medium using the three primary colors of yellow, magenta and cyan as basic developers.
To reduce the amount of developer used when the original image is reproduced on a recording medium, image data of some pixels of the received original image data is converted at regular intervals to data for which developer is not consumed, and printing is performed with respect to the image data including the converted image data. However, when image data of some pixels is converted to data for which developer is not consumed, to reduced the amount of developer consumed, the quality of the image reproduced on the recording medium is lowered.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide a color image printing apparatus for processing image data so that the amount of developer used for the reproduction of an image is reduced without much lowering the quality of the original image.
Accordingly, to achieve the above objective, there is provided a color image printing apparatus which comprises a controller having a plurality of under color tables in which an under color concentration value for black developer, to be used as a substitute for color developer, corresponding to a common concentration value included in each of the three primary colors of yellow, magenta and cyan constituting a pixel display color of the original image, is set differently for a non-toner saving mode than for a toner saving mode, for outputting an under color concentration value for black determined, corresponding to the common concentration value and net concentration data for yellow, magenta and cyan which are obtained by deducting the under color concentration value from concentration data of each pixel display color of the original image, from the under color table corresponding to the toner consumption, an engine for printing a color image on a recording medium with the concentration of developer per color corresponding to the net concentration data for yellow, magenta and cyan, and the under color concentration value for black outputted from the controller, and a toner consumption saving mode selection means for selecting one of the non-toner saving mode and the toner saving mode and outputting a selected toner consumption mode selection signal to the controller.
It is preferred in the present invention that the controller comprises a first memory in which an under color concentration value corresponding to the common concentration value, to be applied in the non-toner saving mode is written, a second memory in which an under color concentration value corresponding to the common concentration value, to be applied in the toner saving mode is written, and an under color removing and black color generating portion for obtaining an under color concentration value corresponding to the common concentration value by selecting one of the first memory and the second memory according to the toner consumption mode selection signal, and generating and outputting as a pixel color data, the net concentration data per color, obtained by deducting the under color concentration value from concentration data of each of yellow, magenta and cyan forming each pixel of the original image, and the concentration data for black corresponding to the under concentration value.


REFERENCES:
patent: 5602637 (1997-02-01), Hara et al.
patent: 5751434 (1998-05-01), Narendranath et al.
patent: 5946450 (1999-08-01), Ebner et al.

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