Abstract: Contactless power and communications links are established between a printer engine and a peripheral device installed on a replaceable printer component. For peripheral devices incorporated within or on the replaceable component, power is inductively transferred from a primary winding on the printer engine to an adjacent secondary winding on the replaceable component without the use of direct physical contact between electrical conductors. In addition, communications between the printer engine and at least one peripheral device on board the replaceable component are provided without making direct physical contact between electrical conductors. The communication task is accomplished in one of several ways. For a first embodiment of the invention, control signals are sent from the printer engine to the replaceable component over the inductive power coupling circuit by switching between two frequencies of alternating current applied to the primary winding on the printing engine.

Abstract: Resistance to shock forces having components acting parallel to the spindle axis of a disk stack is provided by spacing the surface of a circumferential flange of a disk spacer a distance above the surface of a disk in the disk stack which is sufficient to clear the magnetic head and flexure assembly therebeneath during movement thereof during flight to and from a parked position between the confronting surfaces of the circumferential flange and the disk.

Abstract: This application discloses a thermal ink jet printhead and method of manufacture featuring an improved all-metal orifice plate and barrier layer assembly. This assembly includes constricted ink flow ports to reduce cavitation damage and smooth contoured convergent ink ejection orifices to prevent "gulping" of air during an ink ejection process. Both of these features extend the maximum operating frequency, fmax, of the printhead. The nickel barrier layer and the underlying thin film resistor substrate are gold plated and then soldered together to form a good strong solder bond at the substrate - barrier layer interface.

Abstract: This application discloses a thermal ink jet printhead and method of manufacture featuring an improved all-metal orifice plate and barrier layer assembly. This assembly includes constricted ink flow ports to reduce cavitation damage and smooth contoured convergent ink ejection orifices to prevent "gulping" of air during an ink ejection process. Both of these features extend the maximum operating frequency, fmax, of the printhead. The nickle barrier layer and the underlying thin film resistor substrate are gold plated and then soldered together to form a good strong solder bond at the substrate-barrier layer interface.

Abstract: Apparatus and method for testing and determining the operating status of a plurality of ink-ejecting nozzles in a thermal ink jet array. An electrically conductive plate is placed adjacent the ink-ejecting orifices in a test position. An ink droplet appearing from an orifice will, for some brief moment, be in contact with both the orifice plate and the electrically conductive plate. The droplet completes a circuit with a conduction detector and allows current to flow thereby indicating an operative nozzle.

Abstract: A passivation layer in a thermal ink jet printhead is formed or "grown" by a reaction between the materials of the ink jet structure to be protected and an element which will form a chemically inert, electrically insulating, thermally conductive compound. The resistor structure may be of tantalum or tantalum nitride and the electrical conductors therefor may be of aluminum. By subjecting this resistor-conductor structure to a reactive oxide atmosphere, the exposed surfaces of both are anodized so that a surface film of aluminum oxide is formed on the aluminum conductor and a surface film of tantalum pentoxide or tantalum oxynitride is formed on the resistor structure.

Abstract: A corona discharge device for electrophotographic printing is provided in which erasing and primary charging functions are performed by a single device. A screened charging arrangement is used for ion steering, while simultaneous illumination by light produces charge carriers in the photoconducting layer of the drum. In one embodiment, a photochemically etched stainless steel screen is used.

Abstract: An electrostatic voltmeter for measuring the electrostatic potential on a photosensitive drum has a detector capacitively coupled to the drum for providing an output signal in response to the potential on the drum. An AC voltage source is coupled in circuit with the drum and the detector for applying an AC signal across the surface-to-detector capacitance. Circuitry coupled to the detector determines the detector gain in response to the value of the AC component of the output signal and the value of the applied AC signal. The product of the reciprocal of the detector gain and the value of the DC component of the output signal is representative of the electrostatic potential on the surface.