Claims
- 1. A non-impact printhead for use in recording on a recording medium, the printhead comprising:
- a plurality of energizable recording elements;
- driving means, including means for establishing a reference voltage, for energizing said recording elements, said driving means including a current mirror circuit having a master circuit means for generating a reference current and a plurality of first slave circuit means for providing respective driver currents to recording elements selected for energization;
- each first slave circuit means including:
- (a) transistor switching means in series with a respective recording element and switchable from one state to another in response to a signal, and having a control electrode, for controlling driver current to the respective recording element in response to the signal;
- (b) means operating upon the control electrode for switching the switching means to allow driver current to be selectively provided to a respective recording; element for a predetermined period of time;
- (c) second slave circuit means for providing a current path for facilitating changing of the signal at the control electrode from one voltage level to another; and
- (d) second transistor means in series with said transistor switching means for establishing a first voltage signal that is input to one electrode of said transistor switching means, said first voltage signal varying with variations in said reference voltage; said second slave circuit means operating to establish a second voltage signal at a control electrode of the transistor switching means that varies with the reference voltage.
- 2. The printhead of claim 1 and wherein the recording elements are light-emitting diodes.
- 3. A non-impact printhead for use in recording on a recording medium, the printhead comprising:
- a plurality of energizable recording elements;
- means for establishing a reference voltage for driving the recording elements;
- driving means for energizing said recording elements; said driving means including a current mirror circuit having a master circuit means for generating a reference current and a plurality of first slave circuit means for providing respective slaved driver currents to recording elements selected for energization;
- each first slave circuit means including:
- (a) transistor switching means in series with a respective recording element and switchable from one state to another in response to a signal, and having a control electrode, for controlling driver current to the respective recording element in response to the signal;
- (b) means operating upon the control electrode for switching the switching means to allow a level of driver current to b selectively provided to a respective recording element for a predetermined period of time;
- (c) second transistor means in series with said transistor switching means for generating a first voltage signal that is input to one electrode of said transistor switching means, said first voltage signal varying with variations in said reference voltage; and
- (d) second slave circuit means for generating a second voltage signal at a control electrode of the transistor switching means that varies with the reference voltage.
- 4. A driver chip for use on a non-impact printhead for driving a plurality of energizable recording elements; said driver chip comprising:
- electrode means for establishing a reference voltage for driving the recording elements;
- a current mirror circuit including a master circuit means for generating a reference current and a plurality slaved driver currents to recording elements; each first slave circuit means including:
- (a) transistor switching means switchable from one state to another in response to a signal, and having a control electrode, for controlling driver current to a recording element in response to the signal;
- (b) means operating upon the control electrode for switching the switching means to allow driver current to be selectively provided to a respective recording element for a predetermined period of time;
- (c) second slave circuit means for providing a current path for discharge of a capacitive load at the control electrode and;
- (d) second transistor means in series with said transistor switching means for generating a first voltage signal that is input to one electrode of said transistor switching means, said first voltage signal varying with variations in said reference voltage; said second slave circuit means operating to generate a second voltage signal at said control electrode of the transistor switching means that varies with the reference voltage.
Parent Case Info
This is a continuation of application Ser. No. 07/543,507, filed Jun. 26, 1990 now abandoned.
US Referenced Citations (9)
Non-Patent Literature Citations (2)
Entry |
Patent Abstracts of Jap., vol. 4, No. 139 (M-34) (621) 30 Sep. 80 (JP A, 55 095 584, Minowa 19 Jul. 1980. |
Patent Abstracts of Jap., vol. 13, No. 299, (M-847) (3647) 11 Jul. 89 (JP A, 1090 744(Hisane) 7 Apr. 89. |
Continuations (1)
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Number |
Date |
Country |
Parent |
543507 |
Jun 1990 |
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