Abstract: A current steering circuit accomplishes high speed switching of drive current through a vertical cavity surface emitting laser (VCSEL) diode. The preferred embodiment of the current steering circuit includes a first and second schottky diode, connected anode to anode, as the circuit elements used to steer the current that flows into the common connection point of the schottky diodes. The cathode of the first schottky diode is connected to the anode of the VCSEL diode. The cathode of the second schottky diode is connected to one side of a network formed from three resistors. The other side of the network is connected to the output of a CMOS invertor used to buffer the video signal which controls the steering of the current. With the output of the CMOS invertor at a high level, the second schottky diode is in the off state and the first schottky diode is in the on state, forcing drive current to flow through the VCSEL diode.

Abstract: A toner projection printer is provided with a developer surface which manifests a developer bias, and includes a cloud of entrained toner particles. A conductive platen is positioned opposed to the developer surface and manifests a platen voltage that is attractive to the toner particles. An address plate is positioned between the developer surface and the conductive platen. The address plate includes a determined thickness insulator with through pixel apertures. Each pixel aperture has at least a first and second conductors that are electrically insulated from each other by the insulator. A first drive circuit is coupled to the first conductor for controllably applying a row drive voltage which is either a reference potential that exerts a repulsive force on the toner particles or a high voltage which is attractive to the toner particles.

Abstract: A toner projection printer is provided with a developer surface which manifests a developer bias, and includes a cloud of entrained toner particles. A platen is positioned opposed to the developer surface and manifests a platen voltage that is attractive to the toner particles. An address plate is positioned between the developer surface and the conductive platen. The address plate includes a determined thickness insulator with through pixel apertures. Each pixel aperture has at least a first conductive electrode ring positioned within the insulator and connected to a drive plate that is also positioned within the insulator. A first drive circuit positioned on one side of the insulator and is capacitively coupled to the drive plate for controllably applying a row drive voltage thereto. A second drive circuit is positioned on a second side of the insulator and is capacitively coupled to the drive plate for controllably applying a column voltage drive thereto).

Abstract: A modulator for a clock pulse generator receives clock pulses from a clock pulse source, which clock pulses exhibit a reference phase. Delay circuitry is connected to the clock pulse source and includes n tap connections, each connection providing a clock pulse that is delayed by a different phase delay from the reference phase. A multiplexer is connected to each of the n tap connections and provides an output manifesting the clock pulses. A selector circuit controls the multiplexer to sequentially connect any sequence of different ones of the n tap connections to the multiplexer's output, whereby the output manifests a series of clock pulses which have different phase displacements from the reference phase.

Abstract: A linear capacitive encoder is utilized for detecting and encoding the position of a movable member such as a print bar in a dot matrix impact printer. An eight-phase signal is capacitively coupled to one plate of a linear capacitor mounted on the movable print bar. When the print bar moves the phase of the coupled signal changes with respect to the phase of the signal on the other plate of the capacitor, producing an analog signal representing incremental movements of the print bar. The analog signal is amplified and filtered and then converted to a TTL signal representing the position of the print bar. Present position of the print bar is compared to previous position of the print bar to derive signals representing the present direction of movement, direction change and incremental movements of 0.001". Built-in error or hysteresis is added to the direction and direction change signals to prevent false direction changes due to noise. The 0.