Eastman-kodak Company

Kenneth D Kieffer

Pin S Tschang

Hieu T Pham

Yee S Ng

Eric Karl Zeise

Jeremy K Chung

David M Charneski

Michael William Mattern

John J Uebelacker

Richard A Wanzenried

Charles E Ayers

A bus interface device for an application specific integrated circuit handles more than two different clock frequencies and allow for real time switching between the clock frequencies by subsystems of the application specific integrated circuit. In a preferred embodiment, a master state machine is provided that includes a plurality of control input lines and a plurality of control output lines, and a plurality of synchronizing state machines each coupled to one of the control output lines of the master state machine and to a separate clock frequency line. The master state machine, based on signals applied to the control input lines, selectively enables the synchronizing state machines to supply the different clock frequencies to the subsystems of the application specific integrated circuit.

Asic bus interface having a master state machine and a plurality of

A non-impact printhead, for example one that includes a plurality of LEDs, is driven by a current that is programmed to have a linear temperature profile with a desired slope. The change in current with temperature facilitates maintaining of LED uniformity. Linearity between various stages of driver circuitry is maintained by a digital-to-analog converter that includes transistors arranged in a common centroid configuration. Driver current to each LED is provided by a master slave circuit that is dedicated to each LED. Thus, cross-talk between LED channels is minimized.

Non-impact printhead and driver circuit for use therewith

A non-impact printhead for use in recording on a recording medium includes a plurality of energizable recording elements such as LED's. Integrated circuit driver chips are provided that include a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the recording elements selected for energization. A transistor switch is in series with a respective recording element and switchable from one state to another in response to a signal at its control electrode. An enabling circuit operating upon the control electrode switches the transistor switch to allow current to be selectively provided to the recording element for a predetermined period of time. Each of the slave circuits include an additional slave circuit which provides a current path for facilitating changing of the signal at the control electrode from on voltage level to another such as by allowing a capacitive charge at the control electrode to dissipate. A reference voltage is generated for driving the recording elements. A second transistor in series with the transistor switch establishes a first voltage signal that is input to one electrode of the transistor switch. The first voltage signal varies with variations in the reference voltage. The additional slave circuit generates a voltage signal at the control electrode of the transistor switch means that varies with the reference voltage. Thus, variations in the reference voltage will not substantially affect the level of current driven to the LED's during recording of a pixel.

LED printhead with improved current mirror driver and driver chip

An improved printer apparatus includes a print head having a series of point-like radiation sources, such as LED's, arranged in a row for exposing a recording medium. Logic means is provided for determining which of the point-like radiation sources are to be selected for energization. A current driver means responsive to the logic means provides electrical current to the radiation sources selected. A current driver means include a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the radiation sources selected for energization. The master circuit includes a resistor of the type that at least prior to adjustment permits for substantially continuous adjustment of driver current over a range of resistance values. Two independent power supplies are provided to the print head. One power supply provides electrical energy for the logic device at a fixed voltage suitable for the logic devices. A second power supply provides the electrical energy for illuminating the point-like radiation sources. Thus, power to the logic devices is isolated from noise generated during energization of the point-like radiation sources. A variable voltage is provided by this second power supply to permit for flexibility in adjustment of the currents to the point-like radiation sources. This variable voltage may be adjusted in response to aging of the LED's or temperature of the print head.

Printer apparatus

An improved printer apparatus includes a print head having a series of point-like radiation sources, such as LED's, arranged in a row for exposing a recording medium. Logic means is provided for determining which of the point-like radiation sources are to be selected for energization. A current driver means responsive to the logic means provides electrical current to the radiation sources selected. A current driver means include a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the radiation sources selected for energization. The master circuit includes a series of parallel connected transistors that may be instantaneously reprogrammed by digital control signals to said transistors. The characteristics of the transistors vary so that currents from them are scaled by say powers of two to provide an expanded current control capability. Environmental conditions and/or aging often require change in current to maintain desired recording performance. The need for such change may be automatically sensed and a new digital control word sent to the transistors to adjust current to the radiation sources.

Non-impact printer apparatus with improved current mirror driver and

A circuit for generating a set of center pulse-width modulated waveforms comprises a counter having a time changing count, and comparators which compare the count with respective preset counts. The preset counts to the comparators being set so that the set of waveforms created is center pulse-width modulated.

Circuit for generating center pulse width modulated waveforms and

In a non-impact dot printer, such as an LED printer, multiple bits of image data determining the on-time of each LED are latched into an appropriate data register in accordance with a token bit that is passed along a shift register. The shift register is preferably bi-directional to permit for selection of direction wherein identical driver circuitry is provided on opposite sides of a line of LED's.

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Rochester, NY, United States of America

Kenneth D Kieffer