Block Diagram of Fax-Machine

Block Diagram of Fax-Machine Points : block diagram of fax-machine, components of fax-machine, Central Microprocessor, Fax-Modem, Control Panel, Image Buffer and Control, CCD (Charge Coupled Device) Image Sensor, Thermal Printer, Power Supply In spite of the fact, that Fax-machine is small in appearance yet it incorporates a large amount of electronics and mechanical components into its operation. A simplified block diagram of the Fax-machine is shown in the figure. Central Microprocessor It is the heart of all Fax-Machines. The microprocessor manages all the operations of the machine and coordinates the flow of data into and out of the system. The microprocessor consists of the following memories:
a. ROM: It stores the program used to run the machine.
b. RAM: It stores results of calculations, variables, system status flags, or any other information that will change regularly during normal operations. Fax-Modem It generates and detects signals necessary for signal interfacing between the machine and telephone lines. When transmitting, the modem accepts scanned image data from an image memory buffer converts it into an analog form and then feed it to the telephone network. When receiving, an analog signal is received from the telephone network converts it into digital form and stored it in the image memory buffer for processing and printing. Control Panel It serves two functions;
a. Allows the user to enter operating parameters, such as, date, time, print resolutions, baud rate, and desired destination telephone number.
b. It displays the system status and operating parameters. Image Buffer and Control When a Fax-machine receives data, the modem coverts it into digital form and the microprocessor after processing it stores the data in the image buffer memory. Then the microprocessor activates the printing circuit and the data is loaded into the print buffer where it is processed into signals for the fax-machine’s print mechanism. CCD (Charge Coupled Device) Image Sensor For the transmission of a data, the document is fed into the machine. The microprocessor activates the document feeder and scanning circuits. The scanning circuit scan one line at a time using CCD contact image sensors. The line sensor delivers data to the scan controller which processes it and then stored the image data in the image buffer memory. The microprocessor interprets this data and then transfers it to the modem. The modem then transmits the data on the telephone line. Thermal Printer The printer consists of thermal heads and the technique used is thermal line printing, i.e., the image is printed one line at a time onto thermal paper. The thermal printing is now being replaced by electrostatic printing, the technique used in laser printers. This technique allows single sheet paper to be used. Thus, allowing plain paper Fax-machines. Power Supply The power supply operates on 220/110 Vac, 50/60 Hz, single phase. The power needed varies depending on the function performed by the Fax-machine. The primary function and power requirements are: standby, transmission, reception, and copying.