Ink jet printing

Claim 2

A printhead (10) for a continuous-stream ink jet printer, including: a first body (28) having on one surface thereof at least one heating element (18) and addressing electrodes (17) for providing current pulses thereto; a second body (31) having a recess (20) and a plurality of parallel channels (22) in one surface thereof, one end of the channels ending in a side surface and the other end opening into the recess; the first and second bodies being mated and permanently bonded together, so that their respective sides lie in the same plane and the recess and grooves are closed by the first body to produce an ink manifold and closed channels, respectively, with at least one heating element being contactable by the ink, the printhead being intended to be connected with means providing at least one heating element with a continual series of current pulses via the addressing electrodes at a predetermined frequency and power, so that the ink contacting the or each heating element during the application of the pulses sustains a change in its density, viscosity, or surface tension because of a fluctuation in temperature, without the temperature of the ink being raised to a level that would vaporize or produce a change of state therein.

Claim 3

The printhead of claim 1, wherein the heating element is a single heating element located in the printhead manifold; and wherein the channel lengths are very short to reduce the pressure drops along them.

Claim 4

The printhead of claim 1, including a set of commonly-energized heating elements, one heating element being located in each channel in the vicinity, but upstream, of the orifice produced by the intersection of each channel with the side of the second body.

Claim 5

The printhead of claim 3, comprising a single passivated addressing electrode located within each channel, and a passivated common return electrode located between the heating elements and the orifices.

Claim 6

The printhead of claim 3, comprising an individual addressing electrode and an individual return electrode for each heating element; wherein the heating elements are adjacent the orifices and have the same length and width as the channel; and wherein neither the addressing nor return electrodes are within the channels.

Claim 7

The printhead of any preceding claim, wherein the length of the channels is in the range of 12.5 to 250 µm.

Claim 8

The printhead of any preceding claim, wherein the first and second bodies are of silicon.

Claim 9

The printhead of any preceding claim, wherein the second body comprises a layer of photosensitive material that is patterned to provide the channels and recess, and a solid cover that is bonded over the patterned photosensitive layer, so that the channels and recess are provided within the printhead by the sandwiching of the photosensitive layer between the body and the cover, the patterned channels and recess being appropriately aligned with the or each heating element.

Claim 10

A continuous-stream ink jet printer having a printhead comprising: a first silicon body having a surface on which is deposited a plurality of heating elements with each having an individual addressing electrode and a return electrode; a second silicon body having two opposing surfaces of which one has anisotropically etched therein a plurality of parallel channels and holes extending through the thickness of the body, the channels having a triangular cross-section, with each having an associated through hole of pyramidal shape with its apex opening in the other surface, the channels extending between its associated through-hole and a side surface; the first and second bodies being aligned and bonded together, so that one heating element lies at the base of each of the through-holes, and the sides of the first and second bodies are coplanar, so that the channels are closed to form channels from the through-holes to the coplanar surfaces; means for providing pressurized ink to each of the channel outlets, the ink entering the channel from the through-holes; and means for providing a series of continual current pulses concurrently to the heating elements via their addressing electrodes, the current pulses having a predetermined frequency and power, so that the ink contacting the heating elements during the application of the current pulses receives thermal energy pulses which impose a constant cyclic uniform change in the density, viscosity, and/or surface tension of the ink because of a fluctuation in temperature, without incurring a change of state or vaporization.

Claim 11

A continuous-stream ink jet printer having a printhead comprising: a first silicon body having a surface on which is deposited a plurality of heating elements with each having an individual addressing electrode and a return electrode; a second silicon body having two opposing surfaces of which one has anisotropically etched therein a plurality of parallel channels and holes extending through the thickness of the body, the channels having a triangular cross-section, with each having an associated through hole of pyramidal shape with its apex opening in the other surface, the channels extending between its associated through-hole and a side surface; the first and second bodies being aligned and bonded together, so that one heating element lies at the base of each of the through-holes, and the sides of the first and second bodies are coplanar, so that the channels are closed to form channels from the through-holes to the coplanar surfaces; means for providing pressurized ink to each of the channel outlets, the ink entering the channel from the through-holes; and means for providing a series of continual current pulses concurrently to the heating elements via their addressing electrodes, the current pulses having a predetermined frequency and power, so that the ink contacting the heating elements during the application of the current pulses receives thermal energy pulses which impose a constant cyclic uniform change in the density, viscosity, and/or surface tension of the ink because of a fluctuation in temperature, without incurring a change of state or vaporization.

Claim 12

The printhead of claim 9, wherein the surface region of the first body having the heating elements deposited thereon is grooved to increase the surface area of each heating element.

Claim 13

A continuous-stream ink jet printer having a printhead with a plurality of orifices which emit ink streams therefrom toward a record medium, a plurality of ink-charging electrodes positioned at the location where the ink streams break up into droplets, a gutter, deflection electrodes, and means to apply a voltage to each charging electrode in response to binary print and no-print signals, so that only neutrally-charged droplets are printed, and all charged droplets are directed to the gutter for collection and reuse, the printhead comprising: a first body having on one surface thereof a plurality of heating elements, each having an addressing electrode for providing current pulses concurrently thereto; a second body having a recess and a plurality of parallel channels in one surface thereof, the channels ending at one end in a side of the body and at the other end in the recess; the first and second bodies being mated and permanently bonded together, so that their respective sides lie in the same plane with the recess and grooves being closed by the first substrate to produce an ink reservoir and closed channels, respectively, with one heating element lying in each channel, the ends of the channels in the sides serving as the outlets, each heating element being closely adjacent, but upstream of its outlet and being contactable by the ink flowing past it as the ink issues from the outlets, and means for providing the heating elements with a concurrently continual series of current pulses via the addressing electrodes at a predetermined frequency and power to perturb the ink, whereby the ink contacting the heating elements during the application of thermal pulses sustains a change in its density, viscosity, and/or surface tension because of a fluctuation in its temperature, without the temperature of the ink being raised to a level that would vaporize or produce a change of state therein.

Claim 14

A continuous-stream ink jet printer having a printhead with a plurality of orifices which emit ink streams therefrom toward a record medium, a plurality of ink-charging electrodes positioned at the location where the ink streams break up into droplets, a gutter, deflection electrodes, and means to apply a voltage to each charging electrode in response to binary print and no-print signals, so that only neutrally-charged droplets are printed, and all charged droplets are directed to the gutter for collection and reuse, the printhead comprising: a first body having on one surface thereof a plurality of heating elements, each having an addressing electrode for providing current pulses concurrently thereto; a second body having a recess and a plurality of parallel channels in one surface thereof, the channels ending at one end in a side of the body and at the other end in the recess; the first and second bodies being mated and permanently bonded together, so that their respective sides lie in the same plane with the recess and grooves being closed by the first substrate to produce an ink reservoir and closed channels, respectively, with one heating element lying in each channel, the ends of the channels in the sides serving as the outlets, each heating element being closely adjacent, but upstream of its outlet and being contactable by the ink flowing past it as the ink issues from the outlets, and means for providing the heating elements with a concurrently continual series of current pulses via the addressing electrodes at a predetermined frequency and power to perturb the ink, whereby the ink contacting the heating elements during the application of thermal pulses sustains a change in its density, viscosity, and/or surface tension because of a fluctuation in its temperature, without the temperature of the ink being raised to a level that would vaporize or produce a change of state therein.