US 6,473,195 B1 · Image forming apparatus and video data transmitting method therefor

Abstract

An image forming apparatus includes an engine for forming an image corresponding to received video data on a sheet of paper, a main frame buffer memory, an auxiliary frame buffer memory for outputting stored video data along a data transmission path to the engine according to a video clock sync signal, and a first signal when a lower level correspondingly set to at least some amount of the stored video data is reached and a second signal when the stored data reaches a set upper level. This image forming apparatus further comprises a central processing unit for converting print data received externally to video data suitable for driving of the engine and storing the converted video data in the main frame buffer memory, and a direct memory access controller for controlling the main frame buffer memory so that video data stored in the main frame buffer memory is transmitted to the auxiliary frame buffer memory until the second signal is output when a print start signal is input, at an initial stage, and the video data stored in the main frame buffer memory is transmitted to the auxiliary frame buffer memory as much as a set data transmission amount whenever the first signal is input, at a subsequent stage after the initial stage. Also provided is a video sync signal controller for controlling operation and interruption of the direct memory access controller according to a video data output control signal output from the engine and outputting the video clock sync signal. Thus, as the video data can be continuously output to the engine in synchronization with the video clock signal until the print stop signal is generated, speed of print can be increased. Further, a large capacity of storing video data for a memory for video data transmission is not needed.

Claims12

Dependent claims

An image forming apparatus comprising:

an engine for forming an image corresponding to received video data on a sheet of paper;
a main frame buffer memory;
an auxiliary frame buffer memory for outputting stored video data along a data transmission path to said engine according to a video clock sync signal, and outputting a first signal when said stored video data reaches a predetermined lower level and a second signal when said stored data reaches a predetermined upper level;
a central processing unit for converting received print data to video data to drive said engine and storing the converted video data in said main frame buffer memory;
a direct memory access controller for controlling said main frame buffer memory to transmit predetermined video data stored in said main frame buffer memory to said auxiliary frame buffer memory until said second signal is received, at an initial stage, and until said first signal is received, at a subsequent stage after said initial stage, according to a print start signal;
and
a video sync signal controller for controlling operation and interruption of said direct memory access controller according to a video data output control signal output from said engine and outputting said video clock sync signal.

4 more elements

A method of transmitting video data of an image forming apparatus including an engine for forming an image corresponding to received video data on a sheet of paper, a main frame buffer memory, an auxiliary frame buffer memory for outputting stored video data along a data transmission path to said engine according to a video clock sync signal and outputting information of the amount of video data stored, a central processing unit for converting received print data to video data to drive said engine and storing the converted video data in said main frame buffer memory, a direct memory access controller for controlling said main frame buffer memory to transmit predetermined video data stored in said main frame buffer memory to said auxiliary frame buffer memory by using said information on said amount of video data stored in said auxiliary frame buffer memory, and a video sync signal controller for controlling operation and interruption of said direct memory access controller according to a video data output control signal output from said engine and outputting said video clock sync signal, said method comprising said steps of:

(A) determining whether a print start signal is received;
(B) if said print start signal is received, transmitting video data from said main frame buffer memory to said auxiliary frame buffer memory;
(C) determining whether said amount of video data stored in said auxiliary frame buffer memory reaches a predetermined upper level;
(D) if it is determined in said step (C) that said predetermined upper level is reached, interrupting said transmission of video data from said main frame buffer memory to said auxiliary frame buffer memory;
(E) determining whether said amount of video data stored in said auxiliary frame buffer memory reaches a predetermined lower level, which is set to a state that some amount of video data is left as said video data is transmitted to said engine;
and
(F) if it is determined in said step (E) that said predetermined set lower level is reached, transmitting a predetermined amount of video data from said main frame buffer memory to said auxiliary frame buffer memory.

4 more elements

Dependencies are inferred from the claim text.

Image forming apparatus and video data transmitting method therefor

Life of this patent

Image forming apparatus and video data transmitting method therefor

Life of this patent

Abstract

Claims12