Claims
- 1. A printhead for a thermal printer comprising:
- a plurality of individual thermal print elements, each of the thermal print elements having a first end and a second end and undergoing an increase in temperature when said each of the thermal print elements are selected, each thermal print element having a heating current passing therethrough from the first end to the second end;
- a common electrode which has a first side edge and a second side edge, the common electrode being connected via respective conductive traces to the first end of each of the thermal print elements, respectively;
- a first electrical conductor connected to the common electrode and being connectable to a first voltage terminal of a power supply for providing the heating current to the thermal print elements;
- at least one power supply pin connected to the first electrical conductor for coupling to the power supply to provide a connection of the first electrical conductor to the first voltage terminal of the power supply;
- a second electrical conductor connectable to the second ends of the plurality of thermal print elements and being connectable to a second voltage terminal of the power supply, the second voltage terminal being a lower voltage potential than the first voltage terminal;
- at least one ground power supply pin connected to the second electrical conductor for attachment to a ground terminal of the power supply to provide a connection of the second electrical conductor to the second voltage terminal of the power supply for completing a current path for the heating current supplied to the thermal print elements such that the heating current to heat the selected thermal print elements will pass through the power supply pins, through the first electrical conductor, through the common electrode, through the selected thermal print elements, through the second electrical conductor, and through the ground power supply pins;
- a first remote sense electrode connected to the common electrode at a connection point in proximity to the conductive traces such that said first remote sense electrode is at a voltage potential approximately equal to a voltage potential of the first ends of the thermal print elements, the first remote sense electrode providing a voltage sense signal path of the first ends of the thermal print elements;
- a voltage sense pin connected to the first remote sense electrode, the voltage sense pin being connectable to a voltage sense circuit to permit sensing of the voltage potential of the first ends of the thermal print elements using a conductive path different from the current path used to conduct heating current from the power supply to heat the thermal print elements; and
- a remote ground sense electrode coupled to the second electrical conductor at a position in proximity to the second ends of the thermal print elements such that the remote ground sense electrode is at a voltage potential approximately equal to a voltage potential of the second end of the selected thermal print elements.
- 2. The printhead according to claim 1, further including a plurality of other remote sense electrodes connected to the common electrode at positions in proximity to the conductive traces such that each of said plurality of other remote sense electrodes is at a voltage potential approximately equal to the voltage potential of the first ends of each of the thermal print elements that are connected to the conductive traces to which each of the plurality of other remote sense electrodes is proximally located, respectively; and
- a plurality of voltage sense pins connected to the plurality of other remote sense electrodes respectively, the voltage sense pins being connectable to respective voltage sensing circuits to permit the sensing of the voltage potential of the first ends of the thermal print elements proximal to each respective one of the plurality of other remote sense electrodes using a conductive path different from the first electrical conductor that is used to conduct current from the power supply to heat the thermal print elements.
- 3. The printhead according to claim 1, further including:
- a substrate, said substrate supporting the plurality of individual thermal print elements, the common electrode, and at least a portion of the first electrical conductor, the second electrical conductor, the remote sense electrode and the remote ground sense electrode.
- 4. The printhead according to claim 1, further including an electronic control circuit between the remote ground sense electrode and the second ends.
- 5. A printhead for a thermal printer comprising:
- a plurality of individual thermal print elements;
- a common electrode connected via respective conductive traces to a first end of each of the thermal print elements;
- a first electrical conductor connected to the common electrode and being connectable to a first voltage terminal of power supply to carry a heating current for the thermal print elements;
- a second electrical conductor connectable to a second end of each of the thermal print elements via respective conductive traces, the second electrical conductor being connectable to a second voltage terminal of the power supply to carry the heating current for the thermal print elements;
- a remote sense electrode connected to the common electrode at a position in proximity to the conductive traces connected to the common electrode, the remote sense electrode being connectable to a voltage sense circuit; and
- a remote ground sense electrode connected to the second electrical conductor at a position in proximity to the conductive traces connected to the second end of each of the conductive traces, the remote ground sense electrode being connectable to the voltage sense circuit to sense a voltage between the common electrode and the second electrical conductor by a path different from the first and second conductors.
- 6. The printhead according to claim 5 wherein the first voltage terminal is a positive power supply terminal and the second voltage terminal is a ground power supply terminal.
- 7. The printhead according to claim 5 wherein the second voltage terminal is a positive power supply terminal and the first voltage terminal is a ground power supply terminal.
Parent Case Info
This application is a Continuation-in-Part of U.S. patent application Ser. No. 07/951,870, filed Sep. 25, 1992, now abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (3)
Number |
Date |
Country |
54-30849 |
May 1979 |
JPX |
61-185464 |
Aug 1987 |
JPX |
62-297161 |
Jun 1988 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
951870 |
Sep 1992 |
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