Dainippon Screen Mfg. Co., Ltd.

Nobuhito Kohara

Takaharu Yamamoto

Shigeo Murakami

Satoru Kiyohara

Kuniharu Okuda

A printing apparatus has a manual control mode. The manual control mode has a proportion indication, a proportion adjustment key, a selected range adjustment key, and region selection keys. In the manual control mode, an operator selectively touches the region selection keys to select a region in which an ink key opening is to be changed. Next, the operator touches the selected range adjustment key to change the ink key opening of the selected region. The ink key opening is increased or decreased by the percentage indicated at the proportion indication the number of times the selected range adjustment key is touched. The settings made in the manual control mode are stored in a storage section, and are used to control the amount of ink supply during automatic control. Thus, the printing apparatus having the function of automatically controlling the printed density can make partial tone changes.

Printing apparatus for automatically controlling ink supply device

After an ink feeding rate or a dampening water feeding rate is varied, a variation in the ink feeding rate or dampening water feeding rate is prohibited for a waiting period. The waiting period for prohibiting a variation in the ink feeding rate is determined by a pattern area rate of a corresponding region. The waiting period for prohibiting a variation in the dampening water feeding rate is determined by an average pattern area rate of all regions or a minimum pattern area rate among pattern area rates of all regions. When one of the ink feeding rate and dampening water feeding rate is varied, a variation in the other feeding rate is prohibited for a set period of time.

Printing machine for controlling feeding rates by color density measurement

In a first printing process in Steps S through S , ink supply is controlled so that a measured printed density (Vn) is approximately equal to a first target density (V ). This provides a uniform amount of ink remaining on ink rollers after the first printing process. Thereafter, in a second printing process in Steps S through S , printing is performed using a second target density (V ) lower than the first target density (V ). This provides a slightly reduced, uniform amount of ink remaining on the ink rollers. Thus, a novel method of presetting ink is provided which facilitates the formation of a distribution of the new amount of ink at the beginning of the next printing operation and which stabilizes the early start of printing.

Method of presetting ink

A method of feeding dampening water includes a density measuring step for measuring densities of first and second detecting patches and printed adjacent each other on printed matter and presenting a difference in density variations after printing with varied feed rates of damping water and ink, a dampening water feeding step for controlling the feed rate of dampening water based on the densities of the first and second detecting patches and measured in the density measuring step, and an ink feeding step for controlling the feed rate of ink based on the densities of the first and second detecting patches measured in the density measuring step, and the feed rate of dampening water.

Growing community of inventors

Kyoto, Japan

Nobuhito Kohara