Abstract: An ink pen is provided with a protective capping apparatus to protect against damage caused by the ingress of dirt and debris, the accumulation or solidification of ink, the discharge of static electricity or the like. The protective capping apparatus has a protective cap movable between an open position and a closed position. In the closed position the protective cap shields a portion of an ink pen such as the ink-jets or the electrical contacts.

Abstract: An ink-cooled thermal ink jet printhead has an efficient heat exchanger located on the back side of the printhead that eliminates the need for heat sinks. All ink flowing to the firing chamber goes through the heat exchanger. The geometry of the heat exchanger is chosen so that almost all the residual heat absorbed by the printhead substrate is transferred to the ink as it flows to the firing chamber. Additionally, the pressure drop of the ink flowing through the heat exchanger is low enough so that it does not significantly reduce the refill rate of the firing chambers. The heat exchanger can have one or more active heat exchanger sides. The heat exchanger has little thermal mass itself and significantly reduces the thermal mass of printhead by eliminating the need for a heat sink. This reduces the warm-up time of the printhead to a fraction of a second.

Abstract: A printhead includes a substrate with an ink feed aperture extending from a first surface to a second surface and a plurality of heater resistors disposed on it. Primitive groupings of the resistors are coupled to associated group power sources. An ink barrier layer is deposited on the substrate to create ink firing chambers for each resistor. One wall of the ink barrier has a constricted opening through which ink is supplied from the ink feed aperture. A plurality of transistors are disposed in the substrate with each transistor output coupled to an associated one of the resistors and each input coupled to one of a plurality of addressing signal lines. The number of addressing signal lines is equal to the number of resistors in a primitive grouping.

Abstract: An ink-cooled thermal ink jet printhead has an efficient heat exchanger located on the back side of the printhead that eliminates the need for heat sinks. All ink flowing to the firing chamber goes through the heat exchanger. The geometry of the heat exchanger is chosen so that almost all the residual heat absorbed by the printhead substrate is transferred to the ink as it flows to the firing chamber. Additionally, the pressure drop of the ink flowing through the heat exchanger is low enough so that it does not significantly reduce the refill rate of the firing chambers. The heat exchanger can have one or more active heat exchanger sides. The heat exchanger has little thermal mass itself and significantly reduces the thermal mass of printhead by eliminating the need for a heat sink. This reduces the warm-up time of the printhead to a fraction of a second.

Abstract: A method for operating a thermal ink jet printer including a printhead having ink firing heater resistors responsive to pulses provided to the printhead. A sequence of pulse bursts of respective increasing or decreasing pulse energies that span a predetermined pulse energy range is applied to the printhead, each pulse burst comprised of a plurality of pulses having a pulse energy that is associated with such pulse burst and is constant for all pulses in such burst, and each burst having a sufficient number of pulses to allow the printhead to achieve a steady state operating temperature at the pulse energy of the pulse burst. A steady state operating temperature sample is determined for each of the sequence of pulses bursts of different pulse energies to produce a set of temperature samples respectively associated with the increasing pulse energies, and a turn on pulse energy is determined from the temperature samples.

Abstract: A regulator (20) for an ink-jet pen (24) that has a print head (30) for expelling ink from a fluid volume includes a seat (36) mounted to a pen body (26) and having a port (42) formed through it. A valve element (38) is mounted adjacent to the seat for movement relative to the port (42). Magnetic attraction is employed for urging the seat (36) and valve element (38) together to thereby close the port (42) and permit underpressure to develop in the reservoir (22). The valve element (38) and seat (36) are configured and arranged so that when the underpressure within the reservoir (22) rises above the level that may cause failure of the ink-jet print head (30) the valve element (38) moves away from the seat (36) to permit air to enter the reservoir (22), thereby reducing the underpressure to an operable level.

Abstract: An ink jet pen having a main ink reservoir therein connected to a thin film printhead by way of a large diameter standpipe, wherein the diameter of an air accumulating section of the standpipe is sufficiently large to enable ink to pass through the standpipe despite the presence of air in the air accumulating section when the printhead is in operation. The large diameter air bubbles which form in the air accumulating section are easily deformed by suction force from the printhead and thus allow ink to pass through the standpipe between the air bubbles and the walls of the standpipe. This action enables the ink jet pen to operated continuously without undue suction on the standpipe which leads to depriming.

Abstract: The use of lumped resistive elements (28) in an ink feed channel (10) between an ink-propelling element, such as a resistor, (12) and an ink supply plenum (14) provides a means of achieving resistive decoupling and meniscus resonance control with a minimum of deleterious side effects and design compromises typical of prior art solutions. A secondary constriction (30) in the ink feed channel is defined by a width W.sub.2 sufficient to provide physical support for the resistive elements while avoiding resistance to ink refill. The printhead further comprises lead-in lobes (38) for assisting in purging any bubbles in the ink. The lobes are disposed between the projections and the plenum chamber and separate one pair of projections from a neighboring pair.

Abstract: A preloaded check valve disposed in a valve body between an ink reservoir and a printhead has a valve opening pressure or "cracking" pressure at least sufficient to overcome the hydrostatic pressure due to gravity of ink in the reservoir. This prevents depriming or leakage of ink at the orifices of the orifice plate forming part of the ink ejecting mechanism. Ejection of ink during printing creates a pressure differential across the valve sufficient to cause it to open and replenish the ink supply at the ink ejecting mechanism.

Abstract: An orifice plate is provided of an electroformed material which incorporates an integral ink distribution manifold and integral hydraulic separators between orifices. The general approach to the method of making the orifice plate is to first construct a two-part mandrel made up of a "hard" mandrel which can be reused many times and a "soft" mandrel which is renewed each time the mandrel is used. Typically, the surface of the "hard" mandrel is configured by mask and etch techniques, or by mask and electroplate techniques to define the ink distribution manifold and the hydraulic separators, while the "soft" mandrel is configured by mask and develop techniques to define the orifices and edges between orifice plates. Upon completion of the mandrel, its surface is electroplated with a relatively uniform thickness of metal, and the newly electroplated surface having the orifice plates patterned therein is separated from the mandrel.