Color image forming apparatus and color image forming method having overlapping toners
AssigneesKabushiki Kaisha Toshiba, Toshiba Tec Kabushiki Kaisha
InventorsYoshiaki Okano, Masatsugu Hirayama
Life of this patent
Estimating the term…
Abstract
In a digital copying machine according to an image forming apparatus of the invention, when a “thick paper” mode is set through an operation panel, a main CPU sets a gradient of γ for “thick paper” in a γ correction unit of an image processing unit. Thus, a toner attachment amount is controlled and changed from 1.6 mg/cm2 to 1.0 mg/cm2, thereby widening a fixation temperature range for good fixation.
Claims5
An image forming apparatus that forms a color image by overlapping toners of a plurality of colors, on the basis of a plurality of image data corresponding to the plurality of colors, the apparatus comprising:
- setting means for setting a thick paper mode in which an image is to be formed on thick paper, in contrast to an ordinary paper mode in which an image is to be formed on ordinary paper, on the basis of the plurality of image data corresponding to the plurality of colors;
- and
- control means for executing, when the thick paper mode is set by the setting means, a control to reduce a maximum toner attachment amount, compared to the ordinary paper mode, and to set the same fixation temperature condition as in the ordinary paper mode,
- wherein the control means executes, when γ correction is performed for the image data of each color, a control to change a γ correction value for the ordinary paper mode to a γ correction value for the thick paper mode, thereby reducing the maximum toner attachment amount of each color, and
- wherein the control means executes a control to change a transfer bias for the ordinary paper mode to a transfer bias for the thick paper mode, thereby reducing the maximum toner attachment amount.
An image forming apparatus that forms a color image by overlapping toners of a plurality of colors, on the basis of a plurality of image data corresponding to the plurality of colors, the apparatus comprising:
- setting means for setting a thick paper mode in which an image is to be formed on thick paper, in contrast to an ordinary paper mode in which an image is to be formed on ordinary paper, on the basis of the plurality of image data corresponding to the plurality of colors;
- and
- control means for executing, when the thick paper mode is set by the setting means, a control to reduce a maximum toner attachment amount, compared to the ordinary paper mode, and to set the same fixation temperature condition as in the ordinary paper mode,
- wherein the control means executes, when γ correction is performed for the image data of each color, a control to change a γ correction value for the ordinary paper mode to a γ correction value for the thick paper mode, thereby reducing the maximum toner attachment amount of each color, and
- wherein the control means further changes a default value for reducing the maximum toner attachment amount in the thick paper mode.
An image forming apparatus that forms a color image by overlapping toners of a plurality of colors, on the basis of a plurality of image data corresponding to the plurality of colors, the apparatus comprising:
- an image processing unit that includes a γ correction unit for performing γ correction and executes an image process for the image data;
- a printer section that forms an image or paper on the basis of the image data that is processed by the image processing unit;
- a fixing device that heats and presses the paper on which the image is formed by the printer section, thereby fixing the image;
- an operation panel that sets a thick paper mode in which an image is to be formed on thick paper, in contrast to an ordinary paper mode in which an image is to be formed on ordinary paper, on the basis of the plurality of image data corresponding to the plurality of colors;
- and
- a CPU that executes a control to confirm, when the thick paper mode is set by the operation panel, whether toner amount correction is to be executed, to set a gradient of γ for the thick paper mode in the γ correction unit when the toner amount correction is to be executed, and to change a fixation temperature setting condition of the fixing device when the toner amount correction is not to be executed,
- wherein the CPU sets, in the γ correction unit, a “γ” of a correction curve, with which the toner attachment amount is 0.5 mg/cm2 with 256 gray levels in a case of ordinary paper, and sets a “γ” of a correction curve, with which the toner attachment amount is 0.4 mg/cm2 with 256 gray levels in a case of thick paper.
Dependencies are inferred from the claim text.