Abstract: An antimicrobial coating is formed from a biocompatible flexible polymer having incorporated therein an active material having a reducible form of silver, where at least a portion of the active material is exposed at the surface of the polymer. The coating can be applied to the surface of a catheter to inhibit bacterial growth and biofilm formation.

Abstract: An ink jet drop-on-demand printing system comprising an ink jet print head having an ink cavity supplied with a suitable ink. An electromechanical transducer is mounted in mechanical communication with the ink cavity, and a source of electrical signals is provided to selectively actuate the transducer to produce an ink drop of a selected size. To produce ink drops of a selected size the source of electrical signals produces one or more electrical drive signals each separated by a fixed time delay which is short with respect to the drop-on-demand drop production rate. Each electrical drive signal ejects a predetermined volume of ink and all the volumes of ink merge to form a single drop prior to the time the ink drops reach the print medium for printing.

Abstract: An ink jet drop-on-demand printing system having gray scale capability comprising a transducer having a plurality of separately actuable sections. Print data is provided which defines a selected drop volume and control means is provided which is operable in response to the print data to produce drive signals to selectively actuate a particular combination of the separately actuable sections of the transducer to produce a drop of the volume specified by the print data. To provide further control over the drop volume while maintaining the drop velocity within selected limits, the amplitude of the drive signals can also be varied. A further refinement can be provided by varying not only the amplitude of the drive signals but also the pulse width of the drive signals. In a first embodiment the transducer sections are of equal length, while the sections are of unequal length in a second embodiment.

Abstract: A drop-on-demand ink jet printing apparatus comprising a print head having an electromechanical transducer mounted in mechanical communication with the fluid in a fluid chamber within the print head. The transducer is selectively energized with a drop ejecting signal so that one drop of ink is ejected for each drop ejecting signal. In addition the transducer is energized with a series of low amplitude excitation signals which serve to maintain substantially constant dynamic ink characteristics so that quality printing is produced especially during start-up of the apparatus. The excitation pulses can be asynchronous with respect to the drop ejecting signals or synchronous but delayed with respect to the drop ejecting signals. Isolation means are provided to prevent concurrent excitation of the transducer with both a drop ejecting signal and an excitation signal.

Abstract: A drop-on-demand ink jet printing method and apparatus in which the print head has an ink cavity which is filled with ink, and which has a nozzle designed so that ink does not flow out under static conditions. An electromechanical transducer is selectively energized in response to print data signals so that, when energized by an electrical signal, the transducer produces a pressure wave in the ink cavity sufficient to eject one ink drop from the nozzle for each signal above a threshold value. The nozzle is a strongly convergent nozzle and the ink has a viscosity up to 100 centipoise. In the preferred embodiment, the nozzle is formed by anisotropic etching in a silicon substrate. An array of print heads produces a line of high-resolution printing as the print head array is moved across a print medium.

Abstract: A drop-on-demand ink jet printing apparatus in which the print head has an ink cavity which is filled with ink, and which has an orifice designed so that ink does not flow out under static conditions. A fluid inlet chamber is provided to receive ink from the ink supply and this chamber is separated from the ink cavity by a narrow gap. An electromechanical transducer is mounted adjacent the ink cavity and the inlet chamber. The transducer is selectively energized in response to the print data signals so that, when energized by an electrical signal, the transducer reduces the volume in the ink cavity to eject one ink drop from the orifice and substantially close off the narrow gap to substantially close the flow path from the ink cavity to the inlet chamber during the formation of the drop of ink.

Abstract: The object of this invention is to purge any entrapped air from the ink cavity (17) and nozzle orifice (15) of the print head (10) of a drop-on-demand ink jet printer. Purging is accomplished automatically as a part of the start up operation and also if, during operation, the velocity V.sub.s of the ink droplets (26), as sensed by a sensor (41), drops below a preselected reference value V.sub.r.The print head comprises a tubular piezoelectric transducer (11). The transducer is energized with a series of pulses for a preselected short time period and at a repetition rate substantially equal to a resonant frequency of the ink cavity. This effectively purges any entrapped air from the ink system. Except during purging, the transducer operates asynchronously in drop-on-demand mode in response to discrete binary print signals.

Abstract: A drop-on-demand ink jet printer in which the print head includes a cavity having a nozzle portion at one end and a transducer mounted to contract a wall portion of the cavity when energized by a suitable voltage drive pulse. The drive pulses are produced at a predetermined rate but at a selectively controlled amplitude in response to the print data. In cases where no drop is required to print the data, the drive pulse is at a lower amplitude than the threshold voltage level, and for the first drop to be formed following a time at which no drop was formed, the amplitude of the drive pulse is greater than the threshold voltage level. At steady state operation of producing drops in sequence, the amplitude of the drive pulses equals the threshold voltage level.

Abstract: A cartridge comprises a housing containing a flexible record disk connected to a hub that is rotatable relative to the housing by a drive spindle. The cartridge is configured so as to be reversibly mountable on the spindle, for enabling the transducer to access and transducingly engage selectively either face of the disk through respective slots in the housing. The housing is formed of two substantially identical portions, each providing a Bernoulli surface having parts extending at equal angles in opposing divergent directions from a central part that is perpendicular to the plane of disk rotation. In an alternate configuration, the Bernoulli surface has only one part extending in a divergent direction from a remaining part that is perpendicular to the plane of disk rotation.

Abstract: In a helical drive tape apparatus, a rotary head drum is disposed between two sections of a split cylindrical mandrel about which a magnetic tape is guided. The head drum supports at least one magnetic transducer at its periphery, so that the total diameter of the head drum and projecting transducer is greater than the diameter of the adjacent mandrel sections. The projecting transducer has a spherical contoured portion and is configured at its leading edge, relative to the moving tape, to form an air bearing between the head and the tape. The spherical contoured portion and configured leading edge both project beyond the outer surface of the mandrel relative to the tape.