Abstract: In the particular embodiments of the invention described in the specification, a transparency includes a transparent substrate made of a polyester material, a colored ink pattern disposed on one surface of the transparent substrate in the form of three-dimensional ink spots having curved surfaces, and spots of a colorless ink made of a material which has an index of refraction approximately the same as that of the colored ink spots deposited in overlapping relation to colored ink spots as to reduce the dispersion of light by those ink spots. In one embodiment, the colorless ink spots are located in regions having no colored ink spots and in another embodiment the colorless ink spreads to a greater extent than the colored ink.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: In the particular embodiments of the invention described in the specification, a transparency includes a transparent substrate made of a polyester material, an ink pattern disposed on one surface of the transparent sheet in the form of three-dimensional ink spots having curved surfaces and a transparent layer convering the ink spots which has an index of refraction approximately the same as that of the ink spots. The transparent layer is applied to the substrate and the ink spots in the form of a liquid coating which wets the surfaces of the substrate and ink spots and spreads over them to produce a transparent layer having a maximum deviation of about 20 degrees from a plane parallel to the substrate.

Abstract: In the embodiment of the hot melt ink supply unit described in the specification, a block of solid hot melt ink has a peripheral surface formed with a key configuration and a handle is removably connected to the block by a threaded projection. After insertion of the block into a correspondingly keyed opening in a heated reservoir, the handle is turned to separate the handle portion from the block of solid ink. A container provided with a removable seal encloses the block of solid ink and handle to protect the ink from contamination.

Abstract: A transparency includes a transparent substrate such as a polyester material, an ink pattern disposed on one surface of the transparent sheet in the form of three-dimensional ink spots having curved surfaces and a transparent layer covering the ink spots which has an index of refraction approximately the same as that of the ink spots. The transparent layer is applied to the substrate and the ink spots in the form of a liquid coating which wets the surfaces of the substrate and ink spots and spreads over them to produce a transparent layer having a maximum deviation of about 20 degrees from a plane parallel to the substrate.

Abstract: In the particular embodiment described in the specification, a hot melt ink jet system includes a temperature-controlled platen provided with a heater and a thermoelectric cooler electrically connected to a heat pump and a temperature control unit for controlling the operation of the heater and the heat pump to maintain the platen temperature at a desired level. The apparatus also includes a second thermoelectric cooler to solidify hot melt ink in a selected zone more rapidly to avoid offset by a pinch roll coming in contact with the surface of the substrate to which hot melt ink has been applied. An airtight enclosure surrounding the platen is connected to a vacuum pump and has slits adjacent to the platen to hold the substrate in thermal contact with the platen.

Abstract: A pressure pulse liquid droplet ejecting method wherein an induced current within a liquid causes rapid formation of a vapor. The vapor expansion forces droplet ejection. In a preferred method, the induced current is focused by an intermediate dielectric layer placed in the liquid.

Abstract: An electromechanical transducer for an ink jet printer is vacuum impregnated with, e.g., epoxy or silicone materials. The impregnated transducer is less subject to chemical attack and to being shorted out by penetration by conductive inks.