Printhead with reduced interconnections to a printer

A method of selectively energizing heater resistors on a printhead interconnected to a printer, comprising:

• providing constant power to the printhead;
• connecting a plurality of heater resistors through essentially balanced parasitic resistances to the provided constant power;
• providing a plurality of power switching devices, one power switching device of the plurality of power switching devices coupled to each heater resistor, for selectively energizing the heater resistors with power from the power interconnection;
• generating a sequential address signal to specify a first number of at least two but fewer than all of the plurality of power switching devices;
• and
• coupling a print command to selected heater resistors, the print command including the address signal and a print enable signal to specify a second number of the plurality of power switching devices, whereby each of the power switching devices energizes the associated heater resistor coupled thereto when both the address signal and the print enable signal are present for a power switching device which is a member of both the first number and the second number of power switching devices.

A thermal inkjet printhead for interconnection to a printer, comprising:

• a power interconnection for providing power to the printhead;
• a control interconnection for providing a print enable signal and an address generating signal to the printhead;
• a plurality of heater resistors, each operably connected with essentially balanced parasitic resistances to the power interconnection;
• a plurality of power switching devices, one power switching device of the plurality of power switching devices coupled to each heater resistor, for selectively energizing the heater resistors with power from the power interconnection;
• a register for receiving a print enable signal from a control interconnection and applying the print enable signal to one or more switching devices;
• and
• a sequential address generating device for receiving an address generating signal from a control interconnection and generating a sequential address signal for one or more switching devices,
• the switching devices responsive to the address signal and the print enable signal for selectively energizing the heater resistors.

A thermal inkjet printhead for interconnection to a printer, comprising:

• a power interconnection for providing constant power to the printhead;
• a control interconnection for providing a print command to the printhead, the print command including an address synchronizing signal and a print enable signal;
• an address generating device, coupled to the control interconnection, for generating address signals in response to the address synchronizing signal from the print command;
• a print control device, coupled to the control interconnection, for receiving print enable signals from the print command;
• a plurality of heater resistors, each operably connected with essentially balanced parasitic resistances to the constant power interconnection;
• and
• a plurality of power switching devices each coupled to an associated one of the heater resistors for selectively energizing heater resistors with power from the power interconnection, the power switching devices organized into a matrix of groups wherein each of the plurality of power switching devices is a member of a group receiving a same address signal from the address generating device and is also a member of another group receiving a same print enable signal from the print control device, a power switching device responsive to the presence of the address signal and print enable signal.

A thermal inkjet printhead for interconnection to a printer, comprising:

• a power interconnection for providing constant power to the printhead
• a control interconnection for providing a print command to the printhead, the print command including an address synchronizing signal and a print enable signal;
• a data converter for receiving a print command from the printer and converting the print command into the print enable signal;
• an address generating device for generating a sequential pattern of address signals in response to the address synchronizing signal;
• a print control device for receiving print enable signals from the data converter;
• a plurality of heaters resistors, each operably connected with essentially balanced parasitic resistances to the constant power interconnection;
• and
• a plurality of power switching devices associated with the heater resistors for selectively energizing heater resistors with power from the power interconnection, each power switching device responsive to the presence of an address signal from the address generating device and a print enable signal from the print control device to energize one heater resistor.