Abstract: A thermal ink jet printhead and control arrangement therfor includes a housing defining a plurality of ink receiving and emitting chambers with each chamber extending from an aperture in the ink emitting edge of the housing into the interior thereof. A plurality of heating elements are included, one heating element positioned in each of the chambers. An electrically conductive bus positioned within the housing connects the first terminals of the heating elements together. A power source and control system are also provided. The control system is operable to connect the second terminal of a selected one of the heating elements with the power source while simultaneously connecting the second terminals of the remaining heating elements with an electrical ground so that current from the power source flows through the selected heating element and, thereafter, through the electrically conductive bus and remaining heating elements to electrical ground.

Abstract: A thermal ink jet printhead is disclosed having an ink channel geometry that controls the location of the bubble collapse on the heating elements. The ink channels provide the flow path between the printhead ink reservoir and the printhead nozzles. In one embodiment, the heating elements are located in a pit a predetermined distance upstream from the nozzle. The channel portion upstream from the heating element has a length and a cross-sectional flow area that is adjusted relative to the channel portion downstream from the heating element, so that the upstream and downstream portions of channel have substantially equal ink flow impedances. This results in controlling the location of the bubble collapse on the heating element to a location substantially in the center of the heating elements.

Abstract: A method and apparatus for controlling the volume of ink droplets ejected from thermal ink jet printheads is disclosed. The electrical signals applied to heating elements for generating droplet ejecting bubbles thereon are composed of packets of electrical pulses. Each pulse and spacing therebetween are varied in accordance with one or more whole, clock or timing units. The number of pulses per packet and width of pulses and spacing therebetween are controlled in accordance with the manufacturing tolerance variations, the location of the addressed heating element in the printhead, the number of parallel heating elements concurrently energized, and optionally the temperature of the printhead in the vicinity of the heating elements to maintain the desired volume of the ejected droplets.

Abstract: A thermal ink jet printer is disclosed having a printhead with a passageway therein for the circulation of a cooling fluid therethrough. The passageway is parallel and closely adjacent the array of bubble generating heating elements. When the printhead is composed of mated silicon channel and heater plates, the passageway is formed in one embodiment by forming a groove in the heater plate surface opposite the one containing the heating elements and addressing electrodes followed by the mating of a silicon sealing plate having inlet and outlet openings etched therein. Tubes for circulating a cooling fluid, such as ink, are sealingly attached to the inlet and outlet openings. In an alternative embodiment, the groove may be formed in the sealing plate or in both the sealing plate and the printhead heater plate. In another embodiment, the passageway for the cooling fluid is provided by etching a channel in a thick film layer deposited on the heater plate surface opposite the one with the heating elements.

Abstract: An improved ink jet printhead is disclosed of the type having a plurality of parallel ink flow channels which terminate with an ink droplet emitting nozzle, a heating element with a cavitational protective layer thereover located in each channel, and MOS electronic circuitry monolithically integrated within the printhead for applying electrical pulses to the heating elements. The pulsed heating elements produce bubbles momentarily on the protective layer of the heating elements which expel ink droplets from the nozzles. The improvement is obtained by providing multi-layer ionic passivation of the MOS electronic circuitry which is exposable to the ink. This is accomplished through the deposition of a multi-layered, thin film insulative coating thereon consisting of a first layer of doped or undoped silicon dioxide having a thickness of 200 .ANG. to 2 .mu.m followed by a second layer of plasma nitride having a thickness of 1000 .ANG. to 3 .mu.m.

Abstract: Disclosed is a method of fabricating a precision etched, three dimensional device from a silicon wafer, wherein the etching is done from one side of the wafer using a two step silicon etching process. A two-sided deposition of a robust protective layer, such as polycrystalline silicon, is placed over a two-sided deposition of a chemical masking layer such as silicon dioxide. The two layers are concurrently patterned with first and second sets of vias on one side of the wafer, while the opposite side is protected by the protective layer. The protective layer is removed to permit deposition of a second masking layer such as silicon nitride, followed by deposition of a second protective layer. Again, the second protective layer prevents damage to the fragile second masking layer on the wafer backside while its frontside is patterned with a similar set of vias aligned with the first set of vias in the first masking layer.

Abstract: A method for fabricating a coplanar full width scanning array from a plurality of relatively short scanning subunits for reading and writing images. The subunits are fixedly mounted in an end-to-end relationship on a flat structural member with the subunit surfaces containing the scanning elements all being coplanar even though at least some of the subunits have varying thickness. This is accomplished by forming from a photopatternable thick film layer one or more keys on the subunit surface having the scanning elements and associated circuitry and positioning the keys into keyways produced from a photopatternable thick film layer on a flat surface of an alignment fixture. A conformal adhesive bonds a structural member to the assembled subunits to form the full width scanning array.

Abstract: Improved differential optical sensors are mounted at every intersection of the deflection planes of the ink droplets issued by a multi-nozzle printhead of a pagewidth ink jet printer. These sensors are located near the printing plane and gutters of the printer. They comprise first and second input apertures, each being coupled to a light source and fixedly located to direct beams of light to a confronting associated pair of output apertures. The input and output apertures are on opposite sides of the droplet deflection plane, and the input apertures are on opposite sides of a perpendicular line extending from the midpoint between the pair of output apertures. The light beams impinge the pair of output apertures thereby creating differentially detected zero-crossing optical axes at predetermined angles with respect to the perpendicular line therefrom.

Abstract: The method and apparatus for measuring the particle concentration in a fluid that is passed between a reciprocally movable window and a single photodetector. A collimated beam of light is directed through the window and fluid to the photodetector. The window is moved from a first predetermined location to a second predetermined location to vary the light beam path length, thus enabling at least two different photodetector output signals. The ratio of the two signals provides the data needed to determine the particle concentration in the fluid.

Abstract: A thermal ink jet printhead is improved by a specific heating element structure and method of manufacture. The heating elements each have a resistive layer, a high temperature deposited plasma or pyrolytic silicon nitride thereover of predetermined thickness to electrically isolate a subsequently formed cavitational stress protecting layer of tantalum thereon. The pyrolytic silicon nitride permits wet chemical or dry plasma etching delineation of the tantalum without deleterious impact on the silicon nitride, while the delineated tantalum can serve as mask for the wet etch delineation of the silicon nitride. Because of the high deposition temperatures, the aluminum electrodes are patterned and passivated last. Such a construction lowers the manufacturing cost and concurrently provides a more durable printhead.

Abstract: An improved thermal ink jet printhead has a plurality of heating elements in ink channels selectively addressable by electrical signals to eject ink droplets from nozzles located at one end of the ink channels on demand. The heating elements each have a passivated layer of resistive material that has non-uniform sheet resistance in a direction transverse to the direction of ink in the channels. The non-uniform sheet resistance provides a substantially uniform temperature across the width of the resistive layer, so that the power required to eject a droplet is reduced and the droplet size dependence on electrical signal energy is eliminated.

Abstract: A thermal ink jet printhead having an ink inlet and a plurality of droplet emitting nozzles is disclosed in which a patterned gasket is provided around each inlet during mass printhead fabrication. A plurality of printheads are obtained by dicing two mated substrates mounted in a holding film frame. A confronting surface of one of the substrates contains a plurality of sets of heating elements and addressing electrodes. The confronting surface of the other substrate contains a plurality of sets of recesses which serve as ink flow directing channels in communication with the nozzles and a reservoir having inlets in the opposite surface of the other substrate. In one embodiment, a polymeric thick film layer is deposited and photo-patterned to provide each inlet with a gasket, the surface of which is coated with a reflowable and curable adhesive for adherence to an ink supply such as an ink cartridge.

Abstract: A thermal ink jet printhead is improved by using heating element structures which space the portion of the heating element structures subjected to the cavitational forces produced by the generation and collapsing of the droplet expelling bubbles from the upstream electrode interconnection to the heating element. In one embodiment this is accomplished by narrowing the resistive area where the momentary vapor bubbles are to be produced so that a lower temperature section is located between the bubble generating region and the electrode connecting point. In another embodiment, the electrode is attached to the bubble generating resistive layer through a doped polysilicon descender. A third embodiment spaces the bubble generating portion of the heating element from the upstream electrode interface, which is most susceptible to cavitational damage, by using a resistive layer having two different resistivities.

Abstract: An end effector for use with a robotic mechanism is disclosed which is capable of grasping cylindrical workpieces having a varying diameter off center and holding it with six degrees of freedom. The end effector has a plurality of sets of fingers, each set having three fingers which radially approach and retract from the workpiece with a spacing of 120 degrees between the movement direction of the fingers. The movement of each of the fingers in a set are coplanar, and the planar movement of each set of fingers are parallel with each other. Each finger is actuated by its own hydraulic cylinder which causes it to independently engage the workpiece. The cylinders are hydraulically operated by a hydraulic system having a pressurizing pump for flowing fluid from a tank through a bidirectional valve to a series of pilot operated check valves and then to the cylinders. The setting of the bidirectional valve determines whether the fingers grasp the workpiece or release it.

Abstract: A compact mechanical linkage apparatus is disclosed to drive an optical scanning device underneath and parallel to a stationary transparent platen of a reproduction machine. The scanning device includes a carriage having an optical lens assembly. The carriage is adapted to move relative to the machine frame and on guide means for guiding the carriage along a path of travel parallel to the platen whereby successive incremental regions of the document or other object on the platen are scanned and the incremental light image formed by the scanning means are directed to the image receiving member. The carriage is driven along its scanning length by a multiple link mechanism having an input link adapted for full revolution at a constant speed and a one of its links slidably connected to the carriage for imparting thereto a straight line motion at constant speed.

Abstract: An improved thermal ink jet printhead and method of fabrication thereof is disclosed for the type formed by the mating and bonding of first and second substrates. The first substrate is silicon with {100} crystal plane surfaces and has anisotropically etched in one surface thereof a linear series of through recesses together with opposing outer shallow recesses and a plurality of parallel, elongated grooves. The second substrate has a plurality of heating elements and addressing electrodes patterned on one surface thereof. The through recesses with opposing outer shallow recesses serve as a segmented ink reservoir and the elongated grooves serve as ink channels. Adjacent recesses of the segmented reservoir are separated by the dividing walls. The spacing between vias having a dimension which will permit complete undercutting. The undercutting provides ink flow paths. In one embodiment, the shallow recesses of the segmented reservoir are internally fed through the undercut walls.

Abstract: An improved thermal ink jet printhead and method of fabrication thereof is disclosed of the type formed by the mating and bonding of first and second substrates. The first substrate is silicon with {100} crystal plane surfaces and has anisotropically etched in one surface thereof a linear series of separate through recesses and a plurality of parallel, elongated ink channels grooves. The second substrate has a plurality of heating elements and addressing electrodes patterned on one surface thereof. The through recesses serve as a segmented ink reservoir with each segment having an ink inlet, and the elongated ink channel grooves having one end adjacent the segmented reservoir and the opposite end open to serve as ink droplet emitting nozzles. Each segment of the segmented reservoir is isolated from each other by dividing walls. The dividing walls strengthen the printhead, and the separate through recesses reduce the effects of angular misalignment between mask and first substrate crystal planes.

Abstract: An ink jet printhead fabrication process wherein a plurality of printheads are produced from two mated substrates by two dicing operations. One dicing operation produces the nozzle face for each of a plurality of printheads and optionally produces the nozzles. This dicing blade, together with specific operating parameters, prevent the nozzles from chipping and the nozzle faces from scratches and abrasions. A second dicing operation with a standard dicing blade severs the mated substrates into separate printheads. The dicing operation which produces the nozzle face is preferably conducted in a two-step operation. A first cut makes the nozzle face, but does not sever the two mated substrates. A second dicing cut severs the two substrates, but does so in a manner that prevents contact by the dicing blade with the nozzle face.

Abstract: An improved method of fabricating a thermal ink jet printhead of the type produced by the mating of an anisotropically etched silicon substrate containing ink flow directing recesses with a substrate having heating elements and addressing electrodes is disclosed. An etch resistant material on one surface of a (100) silicon substrate is patterned to form at least two sets of vias therein having predetermined sizes, shapes, and predetermined spacing therebetween. The predetermined spacing permits selected complete undercutting by an anisotropic etchant within a predetermined etching time period.

Abstract: Relatively small fluid handling devices having a filter bonded on the surface containing the fluid inlets. An example of such a device is a thermal ink jet printhead. A substantially flat filter is placed at the ink inlet to the printhead by a fabrication process which laminates a wafer sized filter to the aligned and bonded wafers containing a plurality of printheads. The individual printheads are obtained by a sectioning operation, which cuts through the two or more bonded wafers and the filter. The filter may be a woven mesh screen or, preferably, an electroformed screen with a predetermined pore size. Since the filter covers one entire side of the printhead, the relatively large contact area prevents delamination and enables convenient leak-free sealing. The filter prevents the entrance of contaminants into the relatively large inlets of the printhead at an early stage of assembly and packaging.