Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Patent
1992-06-22
1995-10-10
Reinhart, Mark J.
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
358296, 347139, H04N 121, B41J 2435
Patent
active
054574838
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a page printer.
RELATED ART
Page printers are printers which sequentially receive print data from a workstation, a personal computer, or the like and print a page of received data at a time. In this description, an electrophotographic printer is exemplified as a related art
The electrophotographic printer comprises a printer controller, an engine controller, and an engine.
The printer controller is connected to an information outputting portion such as a workstation or a personal computer. The printer controller receives print data from the information outputting portion and develops the print data into image data which can be printed by the engine. In the developing process, when information to be printed is data, print data consisting of character code data, control data, and so forth is converted into image data represented with an image matrix constructed of dots of a predetermined resolution. Since the developing process deals with data which is decomposed into dots of picture elements, this process requires a much longer time than the process which deals with code data.
The engine controller controls the engine in accordance with image data developed by the controller.
The engine prints on a paper the image data received from the engine controller.
In accordance with the light emitting techniques, the engine can be categorized as a laser type, an LED type, a liquid-crystal shutter type, a plasma display type, and so forth. In accordance with each technique, image data is printed in accordance with the printing theory as shown in FIG. 8.
In the figure, the engine has a printing drum 301. When image data is printed on a paper 500, a charger 302 of the engine charges the surface of the printing drum 301. By sequentially emitting light of image data on the surface of the printing drum 301, the surface of the printing drum 301 is photosensitized and an electrostatic latent image is formed. The electrostatic latent image formed on the printing drum 301 is developed by a toner. The developed image is transferred to the paper 500 and then fixed.
When the printer controller receives a form feed signal representing the end of a print page from the information outputting portion, the printer controller sends a control signal to a motor of the printing drum 301 through the engine controller. When the motor receives the control signal, the motor rotates the printing drum 301 at a constant speed, thereby feeding the paper 500 at a constant speed. A light emitting device in accordance with one of the above mentioned techniques successively receives image data and lights every row of a picture element matrix of the image data.
The accurate printing of print data received from the information outputting portion depends on whether or not the electrostatic latent image formed on the charged printing drum 301 is accurately shaped. The electrostatic latent image which is formed on the printing drum 301 is computed by using both the speed at which optical data of every row of a picture element matrix of image data to be printed is irradiated to the printing drum 301 and the rotating speed thereof. Thus, the transmission speed of the image data to the light emitting device and the rotating speed of the printing drum 301 are controlled so that they are synchronized each other.
The rotating speed of the rotating drum 301 is set in accordance with the processing capacity of a processor for the printer controller, that of the engine, the cost of the final product, and so forth along with the considerations of the situations and conditions of the applications thereof.
In the page printer according to band buffer technique, the rotating speed of the printing drum 301 cannot be easily determined.
Then, the band buffer technique will be described.
To store one page (in JIS A4 size) of image data with a resolution of 300 DPI (Dot Per Inch) to a raster buffer RAM 109, since this image data is constructed of 2338.times.3407 picture elements (in the U.S. letter size, 2400.times.3200
REFERENCES:
patent: 3971044 (1976-07-01), Findley et al.
patent: 3999168 (1976-12-01), Findley et al.
patent: 5086309 (1992-02-01), Iida et al.
Oki Electric Industrial Co. Ltd.
Reinhart Mark J.
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