Abstract:
A droplet generator for a continuous stream ink jet print head comprising: an elongate cavity (13) for containing the ink; nozzle orifices (15) in a wall of said cavity for passing ink from the cavity to form jets, said nozzle orifices extending along the length of said cavity; and actuator means for vibrating the ink in said cavity such that each said jet breaks up into ink droplets at the same predetermined distance from said wall of the cavity, said actuator means being disposed on the opposite side of said cavity to said wall and comprising vibration means which is divided up along the length of said cavity at least partially into at least two parts, characterised in that said actuator means further comprises a backing member (21) disposed further from said cavity than said vibration means and secured to and bridging said parts into which said vibration means is at least partially divided, said vibration means being interposed in line between said backing member and said cavity.
Abstract:
An integrated circuit includes a monitor circuit (1, 3) designed to fail prior to the rest of the integrated circuit whilst allowing the rest of the integrated circuit to function. A warning circuit provides an indication that the monitor circuit (1, 3) has failed.
Abstract:
Pleochroic fluorescent dyes of general formula (I), in which R is hydrogen or an aliphatic hydrocarbon radical containing not more than 20 carbon atoms and -CH2- between carbon atoms or adjacent to the bicyclo[2.2.2]octane residue may be replaced by -O-, may be dissolved in liquid crystal host material to form displays which are caused to fluoresce by incident low-energy ultraviolet initially absorbed by the liquid crystal host material and then internally transferred to the fluorophor. These dyes have greater stability to ultraviolet than other perylenedicarboxylic diesters while possessing good fluorescent properties and satisfactory order parameters. In formula (I), R is preferably a straight or branched alkyl and/or cycloalkyl group having 3 to 10 carbon atoms, preferably 5 to 7 carbon atoms. The liquid crystal host material preferably contains an energy-transfer agent such as a 4-substituted 4''-cyanoterphenyl. The 4-pentyl- and 4-propyl- bicyclo[2.2.2]oct-1-yl perylenedicarboxylates of formula I and solutions of these dyes in nematic liquid crystal host "E7" (a mixture based on cyanobiphenyls containing 8% 4-pentyl-4"-cyanoterphenyl) are described in examples.
Abstract:
An anti-clogging nozzle system for a continuous ink-jet printer is disclosed. A printing nozzle (10) has both an ink inlet (12) and an ink outlet (28) permitting constant ink flow behind the nozzle orifice during printing. A pressure sensor (38) monitors the ink flow and signals clogs to an automatic unclogging system (34, 36). The unclogging system includes a control circuit (36) to initiate an unclogging operating cycle when necessary. One of two unclogging modes is employed, both of which require the control system (36) to operate an unclogging valve (34) to vary pressure in the ink return line (28).
Abstract:
A hot melt ink compositon for use in continuous ink jet printing comprising an electrolyte and an electrolyte-solvating and dissociating compound, said ink being solid at room temperature, i.e. about 25 DEG C, said ink liquefying at a temperature in the range of about 75 DEG C to about 175 DEG C, and said ink in the liquid stage having a conductivity of greater than about 100 microsiemens/cm.
Abstract:
A polarisation controller comprises at least one stack of nematic liquid crystal cells (1, 3) arranged such that radiation (101) incident on the stack will pass through each cell in the stack in sequence. Synchronised electric or magnetic fields are applied across the cells so as to change the phase retardation of the radiation transmitted through each cell by a chosen amount, the optical axes (5, 7) of the cells being oriented with respect to each other such that the polarisation of radiation incident on the controller is caused by the controller to change from a first state to a second state.
Abstract:
A radiation meter for measuring the intensity of incident UV radiation in a predetermined wavelength band against a background of broadband radiation (24), such as sunlight, includes a sheet (3) of a material incorporating a fluorescent dye. The dye is selected to absorb radiation in the predetermined wavelength band and consequently to emit fluorescent radiation. The fluorescent radiation is internally reflected within the sheet and emerges from an edge of the sheet, where it impinges on a photodiode (9). The photodiode produces an output which is dependent upon the intensity of the UV radiation. This output is used to drive a suitable display. The unwanted background radiation passes through the sheet without causing fluorescence of the dye, and is absorbed in an absorbant backing layer (7). The photodiode is so positioned and screened that the background radiation cannot impinge upon it. A particularly advantageous use of the meter is for measurement of the intensity of UVB radiation, which is the cause of sunburn and skin cancer.
Abstract:
A water-in-oil emulsion duplicating ink comprising a water phase comprising an aqueous dispersion of oxidized carbon black and an oil phase comprising a saturated oil and an unsaturated oil. The ink compositions of the present invention dry quickly, and exhibit minimal dispersion in the paper upon which the ink is applied. The ink compositions of the present invention remain liquid for extended periods of time upon exposure to the atmosphere.
Abstract:
In order to overcome the effect of a magnetic object in a subject (2) under investigation, the invention provides NMR apparatus which is operable at more than one RF frequency. The apparatus follows normal practice as far as obtaining an NMR response or image from a given nuclear species is concerned, but, in addition, interrogates the nuclear spin system at a frequency which is different from the resonance frequency normally used for the given nuclear species, as determined from the applied magnetic field Bo. This additional frequency is chosen so that the nuclei of interest, which would normally give a resonance signal or an image at a frequency f1 in the applied magnetic field Bo, when located in the modified magnetic field close to a magnetised or magnetisable object give a response at a different frequency f2. Detection of a signal at the frequency f2 then indicates the presence of the chosen nuclei close to the magnetised or magnetisable object.
Abstract:
A method of providing a damage-resistant optical coating on a component (10) comprises depositing on the component one or more transparent or semi-transparent layers (5 - 9) of predetermined thickness by forming a required number of monomolecular layers of a material of a predetermined refractive index, using the Langmuir-Blodgett process. By use of this process, the resulting transparent or semi-transparent layers are damage-resistant, particularly to large laser output pulses. Furthermore, the thickness of the layers can be very accurately controlled, and, by adjustment of the constituents of the material in the Langmuir-Blodgett trough, the refractive index of each layer can be accurately determined. The transparent or semi-transparent layers may be alternately of high and low refractive index, and the optical thickness can be controlled to provide an anti-reflective or reflective coating.