Abstract: A drop-on-demand ink jet has an ink chamber coupled to a source of ink, and an ink drop orifice with an outlet. An acoustic driver produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet. The driver is driven with bipolar drive pulses having a refill pulse component and an eject pulse component of a polarity which is opposite to the refull pulse component. The refill and eject pulse components are separated by a wait period. The drive pulses may be adjusted to minimize their energy content at a frequency corresponding to the dominant acoustic resonance frequency of the ink jet. This will accelerate drop breakoff, optimize drop shape and minimize drop speed variations over the range of drop printing rates. The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change inks to achieve high print quality at high print rates.

Abstract: A drop-on-demand ink jet has an ink chamber coupled to a source of ink, and an ink drop orifice with an outlet. An acoustic driver produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet. The size of the ink drops may be varied, such as by driving the acoustic driver with varying drive signals, preferably comprising individual or combinations of plural bipolar drive pulses. The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change inks.

Abstract: A color image copying system (10) employs a cathode-ray tube (16) that employs a diffraction grating face plate (38) which for each image disperses to predetermined focal regions (132, 143, and 136) light rays of corresponding wavelengths. The light rays sequentially expose a region 80 of a scrolled light-sensitive medium (42) to form a composite color copy of the image. Bands of phosphorescent materials (32, 34, and 36) are applied on angularly inclined subregions (146, 148, and 150) of the inner surface (144) of the face plate and intercept a raster-scanned electron beam (22) to develop light of the different wavelengths. The inner surface of the face plate has angularly inclined subregions (146, 148, and 150) that provide for incident light rays of each wavelength an angular offset of equal magnitude but opposite rotational sense to compensate for changes in diffraction angles (.beta..sub.1, .beta..sub.2, and .beta..sub.