Abstract: A system connecting a printer and a host computer includes a signal processing unit, a printing unit, a DC/DC converter converting a power supply voltage into a lower voltage required by the signal processing unit and outputting the converted voltage to the signal processing unit, an input unit receiving a printing command, and a power supply controlling device. The power supply controlling device includes a first switching unit, a pulse width modulating unit, a power supply switch providing a power on/off signal from a user, and a power supply controlling unit outputting a control signal to the pulse width modulating unit to control the first switching unit to perform an on/off operation corresponding to the power on/off signal from the user.

Abstract: A device for preventing a printer header from overheating includes a heater driving portion which is driven in response to a heater driving control signal, a heater emitting heat using electricity which is supplied by the heater driving portion, a substrate temperature detector detecting a temperature of a header substrate where the heater is mounted, a reference voltage generator generating a reference voltage, a comparator comparing a voltage detected by the substrate temperature detector with the reference voltage, a power control portion controlling a driving voltage supplied to the heater in response to a power control signal and controlling the driving voltage in accordance with an output signal of the comparator, and a control portion controlling the heater driving portion and the power control portion in accordance with transmitted printing data.

Abstract: A method of and apparatus for using current in an ink-jet printer having a head including a plurality of nozzles for each color and nozzle driving units driving the nozzles include detecting an amount of the current flowing through the head, dividing the detected amount of the current by a unit current and determining a result of the division as a first nozzle number, and accumulating first nozzle numbers and determining a result of the accumulation as a second nozzle number. A state of the ink-jet printer is determined using the second nozzle number, and the unit current corresponds to current flowing through a nozzle through which ink is ejected.

Abstract: An ink cartridge identifying apparatus of a printer which is capable of selectively mounting two or more kinds of ink cartridges therein for printing includes an identifying unit, a sensing unit, and a micro processing unit. The identifying unit is prepared on a body of the ink cartridge. The sensing unit is prepared in a carriage mounted with the ink cartridge therein so as to sense the identifying unit. The micro processing unit identifies what kind of cartridge the ink cartridge is, by using signals detected from the sensing unit. In this structure, it is possible to identify the kind of the ink cartridge without adding electrical contact nodes to a flexible printed circuit of the ink cartridge.

Abstract: An inkjet printer checks whether each nozzle on a printing head is normal, and upon receipt of a nozzle checking command for a nozzle of a printing head through an inputting unit, cuts off a first driving power supply provided during a normal operation and drives in sequence a plurality of nozzle driving units using a second driving power supply. Through such operation, the inkjet printer determines a state of each nozzle driving unit in accordance with an output signal from a comparator comparing a voltage drop level during driving of each nozzle driving unit with a reference voltage, and then stores a nozzle number corresponding to the nozzle driving unit whose failure is detected. Upon completion of checking for each nozzle driving unit, the stored nozzle number representing an abnormal nozzle is displayed on a display.