Abstract: A digital-to-analog converter includes a plurality of constant current sources and a calibration circuit for measuring the value or relative value of the current provided by one or more of the sources without interrupting operation of the digital-to-analog converter. The calibration circuit carries out a routine whereby a number of measurements are obtained and averaged. Error signals in accordance with the averaged measurements are produced and used to correct for drift in the components of the current sources. Error correction may be achieved by adjusting the regulators themselves or by adding correction signals at other parts of the circuit.

Abstract: An ink jet array printer has at least one row of printing guns. The guns deposit drops which are charged and deflected for printing on a printing surface moving relatively to the printer in line sections which together form a transverse printing line. The charging of the drops is effected by applying to the charge electrode of each gun, under the control of printing information, a periodic voltage waveform of sufficient period to span a raster of successively formed drops which are employed for printing the corresponding line section, the printing lines being successively formed at the frequency of the voltage waveform.

Abstract: A torque wrench comprising a driving head, an operating arm and an adjustable torque limit signalling means characterized by:a first arm drivingly connected with the driving head,a second arm pivotally coupled to the driving head,a torque limit signalling assembly slidably adjustable in position along one of the arms for selecting a torque limit,the assembly including a non-linear spring means arranged to transmit force between the arms and to signal the occurrence of an abrupt change in spring force in accordance with the selected limit. Preferably the non-linear spring is constituted by a disc washer, and one of the arms is calibrated.

Abstract: Apparatus and method for generating a dispersed dot half tone picture from a continuous tone picture involves the making of a thresholding decision at each picture element to decide whether or not a dot is printed in the output picture and is characterized in that cumulative weighted sums of the errors between the original continuous tone picture and the output half tone picture at each picture element are held for each column of the picture matrix and from these column sums of errors a sector sum of errors is formed and used in the thresholding decision. The column and sector sums of errors are up-dated by simple recursive relationships. Edge enhancement is introduced in a simple manner obviating the need to calculate a local greyscale average. Distracting patterns of dots in the output picture are broken up by the use of carefully selected threshold values.

Abstract: A loom in which each warp yarn passes through a retraction region and a shedding region, and in which means are provided for creating gaseous fluid flow along each warp yarn so that the yarns, or those that are not otherwise restrained, are moved to form a loop in the shedding region, the loops, or selected ones of them, being separated from the warp yarn sheet by gaseous fluid flow to form a shed, and means are provided for mechanically displacing portions of the yarns in the retraction region to move the yarns longitudinally into a path of predetermined length so as to draw the yarns into tension in the shedding region to close the shed. The means for drawing the yarns into tension may also be employed to draw the fell of the woven fabric against a fixed reed to beat up the inserted weft yarn.