Image forming apparatus and print control method therefor

#This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C .sctn.119 from an application entitled Print Control Method Of Image Forming Apparatus earlier filed in the Korean Industrial Property Office on 14 Aug. 1995, which was duly assigned Ser. No. 25003/1995 by that Office.

#1. Field of the Invention

#The present invention relates to an image forming apparatus which prints an image on a recording medium, and particularly to a method for controlling a print engine unit of the image forming apparatus which prints the image on the recording medium by a page unit.

#A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detail description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:

#FIG. 1 is a block diagram illustrating the structure of a page printer;

#FIG. 2 is a flow chart illustrating one print control operation of the print engine unit of the page printer of FIG. 1;

#FIG. 1 is a block diagram illustrating a printer using the electrophotographic developing method, which is a type of an image forming apparatus for printing an image on a recording medium by a page unit. As shown in FIG. 1, the printer comprises a video controller 10, an operating panel equipment 18 (referred as to OPE, hereinafter) and a print engine unit 20. Video controller 10 includes a computer interface 12, a video control unit 14 connected to OPE 18, and an engine interface 16 connected print engine unit 20. Computer interface 12 provides an interface for transmitting/receiving signals between a host computer (not shown) and video control unit 14. Video control unit 14 communicates with the host computer and controls print engine unit 20 according to command input from the host computer and from OPE 18 to perform various operations including an image print operation. Video control unit 14 generates image data, of an image desired to be printed, from print data received from the host computer and provides the generated image data to print engine unit 20 via engine interface 16. Engine interface 16 provides an interface for transmitting/receiving signals between video control unit 14 and print engine unit 20. OPE 18 includes a number of keys (not shown) for inputting various kinds of commands, and a displaying device (not shown) for displaying information in accordance with the commands and print operations.

#Print engine unit 20 comprises a video interface 22, an engine control unit 24, an input/output (I/O) interface 26, a sensor circuit 28, a mechanism driving unit 30 and an electrophotographic developing unit 32. Video interface 22 provides an interface for transmitting/receiving signals between video controller 10 and engine control unit 24. Engine unit 24 controls mechanism driving unit 30 and electrophotographic developing unit 32 via I/O interface 26 according to the commands generated by video controller 10 and OPE 18 in order to print an image in accordance with image data inputted from video controller 10 on printing paper by page units. Engine control unit 24 senses operation states of each element of print engine unit 20, paper feed and transfer states, the present amount of developing material and so on, from signals transmitted thereto from sensor circuit 28 via I/O interface 26. I/O interface 26 is connected in common to engine control unit 24, sensor circuit 28, mechanism driving unit 30 and electrophotographic developing unit 32 to thereby interface input/output signals of engine control unit 24. Sensor circuit 28 drives various sensors for sensing an operation state of each element of print engine unit 20, paper feed and transfer states, the present amount of developing material, and so on, and provides a sensing signal of each sensor to engine unit 24. Mechanism driving unit 30 drives many kinds of mechanisms for feed, transfer and print of printing paper according to the control of engine control unit 24. Electrophotographic developing unit 32 is controlled by engine control unit 24 to print the image in accordance with image data on printing paper by using an electrophotographic developing method.

#Referring, now, to FIG. 2 a flow chart illustrating one print control operation for controlling print engine unit 20 of FIG. 1 is shown. When power to print engine unit 20 is ON, engine control unit 24 initializes each element of print engine unit 20 in step 100. After the initializing step, engine control unit 24 executes a stand-by mode of operation, step 102, during which time engine control unit 24 provides information to video controller indicative of the stand-by state and waits for reception of a print command signal, step 104, from video controller 10. When data desired to be printed is present, video controller 10 applies a print command signal to print engine unit 20, and engine control unit 24 detects the print command signal in step 104. Engine control unit 24 drives mechanism driving unit 30, step 106, to start a paper feed operation in response to the print command signal. After sensors of sensor circuit 28 detect that the paper fed during step 106 has been reached a print position by detecting, for example, the leading edge of the paper, print engine unit 20 goes into a print state and engine control unit 24 transmits a vertical synchronizing request signal to video controller 10 through video interface 22 in step 108, and in step 110, a time-out variable is cleared.