Abstract: A detection circuit (30, 32) for carrying out a rapid search technique for locating the position of a stylus (12) relative to a display screen (10). A microprocessor (34) and related components select a group of light detectors (20, 28) that are positioned near the display screen (10). The summed output current of the selected group of detectors (20, 28) is monitored to determine whether the output of any detector in the selected group is reduced because of the presence of a stylus (12). Whenever the selected group shows such reduction in output current, that selected groups is divided into two subgroups. The subgroup having reduced current output due to the presence of the stylus (12) is further divided until the particular detector(s) having reduced output current is found, the position of the detector is correlated to the location of the stylus (12) relative to the screen (10).

Abstract: An extremely compact ink jet print head has an array of closely spaced nozzles which are supplied from densely packed ink pressure chambers by way of offset channels. The ink supply inlets leading to the pressure chambers and the offset channels are designed to provide uniform operating characteristics to the ink jet nozzles of the array. To enhance the packing density of the pressure chambers, the ink supply channels leading to the pressure chambers and offset channels are positioned in planes between the pressure chambers and nozzles. An optional ink purging pathway is provided for purging bubbles and other contaminants from the chamber side of the nozzles. The ink jet print head may be assembled from plural plates with features in all but the nozzle defining plate being formed by photo-patterning and etching processes without requiring machining or other metal working.

Abstract: The present invention entails an accurate, sensitive, and stable means of mounting a print head to a movable carriage assembly of the type used in computer output printers. The invention uses one pair of planar mounting surfaces and one pair of angled mounting surfaces between the print head and the carriage of a print head assembly. A pair of pivoting clamping plates apply a force that urges both pairs of mounting surfaces together while simultaneously providing adjustment of the translation of the print head relative to the carriage. The translation across the oppositely angled surfaces on two of the four mounting surfaces provides an accurate azimuthal angle adjustment for the print head. Because the other mounting surfaces are in the same plane, the translation affects only the azimuthal angle.

Abstract: An apparatus for and a method of addressing data storage elements (16) employs an ionizable gas to address the storage elements for storing data in and reading data out of them. The storage elements are defined by the overlapping areas of multiple column electrode (18) extending in a common direction on a first substrate (48) and multiple channels (20) extending in a common direction on a second substrate (54). A layer of dielectric material (46) separates the first and the second substrates, which are positioned face-to-face and spaced-apart with the direction of the channels transverse to that of the column electrodes. Each of the channels is filled with an ionizable gas and includes a reference potential electrode and a row electrode electrically isolated from each other.

Abstract: A high-gain solid-state amplifier (20) includes an amplification stage including a transistor (Q.sub.1) having a current-dependent transconductance value. The transistor is operatively connected to a load resistor (R.sub.L1) through which a load current (I.sub.1) flows. The value of the load resistor together with the transconductance value affects the voltage gain of the amplifier. A resistor (R.sub.2) provides a supplemental bias current (I.sub.2) to a current summing node (A). The current summing node sums the load current and the supplemental bias current and provides the transistor with a total current (I.sub.d) that affects the transconductance value. The value of the supplemental bias current is chosen to supplement the load current to provide a predetermined total current so that the voltage gain may be adjusted by adjusting the load resistor without changing the transconductance value.

Abstract: A high-gain, low noise solid-state multiple stage amplifier (12) includes a phase-inverting input stage (20) and a phase non-inverting output stage (30). The input stage includes a first transistor (Q.sub.1) having a current-dependent transconductance value. The first transistor is operatively connected to a load resistor (R.sub.L1) through which a load current (I.sub.1) flows. An amplified phase-inverted version of a time-varying signal applied to the input (V.sub.i) is developed across the load resistor. The value of the load resistor together with the transconductance value affects the voltage gain of the input stage. A resistor (R.sub.2) provides a supplemental bias current (I.sub.2) to a current summing node (A). The current summing node sums the load current and the supplemental bias current and provides the first transistor with a total current (I.sub.d) that affects the transconductance value.

Abstract: A polarization insensitive optical attenuator (10,40) uses a polymer-dispersed liquid crystal (PDLC) film (14,56) to provide attenuation control over a wide range of attenuation values. The attenuator has a relatively low minimum attenuation and reliable light transmission with minimal insertion loss. The present invention is also adaptable for use with a temperature controller (200) that stabilizes the PDLC film, which promotes more uniform, predictable attenuation values.

Abstract: A serial-to-parallel analog CCD GaAs device provides high speed A/D or D/A conversion. A high speed analog signal is sampled by shifting the analog data serially into "n" CCD elements. Then a parallel load pulse transfers the analog data into multiple CCD holding elements. A bank of A/D converters converts the analog data. Conversely, the outputs of a bank of D/A converters are loaded in parallel into a serial CCD device of "n" elements. The serial CCD device is shifted out serially to complete the conversion to an analog signal.

Abstract: A solid-state electrical circuit (10) includes a reference diode (D1) and multiple diodes (D3-D14) connected in electrical series to produce a substantially temperature-invariant output reference voltage. The reference diode is characterized by a forward voltage drop (V.sub.D1) that changes in accordance with a temperature coefficient. The multiple diodes, which have selected junction areas (A1 and A2) and receive one of two different forward-bias currents (I1 and I2), are electrically interconnected to establish a net voltage (.DELTA.V.sub.Di) that equals the forward voltage drop across the reference diode and changes in accordance with a net temperature coefficient of substantially equal magnitude but of opposite sign to the temperature coefficient of the reference diode. The output reference voltage equals the sum of the forward voltage drop across the reference diode and the net voltage established by the multiple diodes.

Abstract: A method and apparatus for reversibly transforming color, which is selected from a gamut of colors producible by the primaries of a color display device (20), into a perceptually uniform color space. The coordinates of the color space are readily convertible into internationally accepted standards for color measurement. Also provided, is a method for transforming the color space coordinates of a selected color into the corresponding relative primary intensity levels of the display device (20).

Abstract: A serial-to-parallel analog CCD GaAs device provides high speed A/D or D/A conversion. A high speed analog signal is sampled by shifting the analog data serially into "n" CCD elements. Then a parallel load pulse transfers the analog data into multiple CCD holding elements. A bank of A/D converters converts the analog data. Conversely, the outputs of a bank of D/A converters are loaded in parallel into a serial CCD device of "n" elements. The serial CCD device is shifted out serially to complete the conversion to an analog signal.

Abstract: A liquid crystal cell (10) includes a chiral liquid crystal material (16) captured between a pair of electrode structures (12 and 14). The liquid crystal material is of a type that exhibits in consecutive order chiral semitic nematic, smectic A, and chiral phases at successively lower temperatures. In a preferred embodiment, the chiral phase is of the smectic C type. The electrode structures have director alignment layers (22 and 22') deposited on their inner surfaces. The directors (28 and 30) of the liquid crystal material in the nematic phase in contact the alignment layers align at relatively large tilt bias angles relative to the alignment layer. The tilt bias angles of the directors in contact with one of the electrode structures are defined in a rotational sense which is opposite that of the tilt bias angles of the directors in contact with the other electrode structure.

Abstract: An addressing structure uses an ionizable gas to address data storage elements (16) defined by the overlapping areas of multiple column electrodes (18) on a first substrate (48) and multiple channels (20) on a second substrate (54). A layer of dielectric material (46) separates the first and second substrates. Each of the channels is filled with the ionizable gas and includes a reference potential electrode that receives a data drive signal and a row electrode that receives a data strobe signal. For each storage element, the ionizable gas functions as an electrical switch that changes between a conducting or plasma state and a nonconducting or de-ionized state in response to an applied data strobe signal. The ionizable gas functions to either store data in or read data out of the storage element.

Abstract: A stereoscopic graphics display terminal (10) having an image data processor (22) generates stereoscopic image data from three-dimensional image data. In a preferred embodiment, the graphics display terminal receives from a main or host computer (12) three-dimensional image data corresponding to a three-dimensional representation of an object. The three-dimensional image data are typically generated by an application program that resides in the host computer. The image data processor includes an image orienting system (74) that receives the three-dimensional image data and adaptes such data to represent a preselected orientation of the object and thereby provide an observer with a preselected view of the object. The adaptation of the three-dimensional image data by the image orienting system entails image manipulations that include rotating, translating, and scaling the size of the image.

Abstract: A high-speed electrical circuit (10) provides an output signal that is a delayed version of a digital input signal. The circuit includes two subcircuits (20 and 22) which receive the input signal and whose outputs (52 and 56) are summed together. The subcircuits provide two different paths for the digital input signal to travel, one path providing a long time delay and the other path providing a short time delay. Each of the subcircuits comprises a pair of emitter-coupled transistors (24 and 26; 28 and 30). The subcircuit providing the long delay time includes transistors which have large areas and collector resistors that promote relatively slow transistor switching response time. The subcircuit providing the short delay time is optimized for high speed operation.

Abstract: An apparatus for and a method of addressing data storage locations (80) employs an electron beam (76) to address such storage locations and thereby store data in and read data out of them. The storage locations are defined by the overlapping areas of multiple column electrodes (62) extending in a common direction on a first substrate (82) and rows (120) addressed by an electron beam (76) and extending in a common direction on a second substrate (54). A layer of dielectric material (52) separates the first and the second substrates, which are positioned face-to-face and spaced-apart with the direction of the addressed rows transverse to that of the column electrodes. The column electrodes receive data drive signals. The addressing apparatus is configured so that for each storage location secondary electrons emitted by the electron beam striking the location function as an electrical switch that changes between a conducting state and a nonconducting state in response to the presence of the electron beam.

Abstract: A multiple beam cathode-ray tube employs a bipotential electrode structure to provide acceleration and convergence of the electron beams without the use of a resistive helix coil. In a preferred embodiment, the bipotential electrode structure (10) is employed in a cathode-ray tube (14) in which a cathode (28) and a grid electrode structure (30) cooperate to form plural beams of high velocity electrons. The bipotential electrode structure includes an immersion lens cylinder (16) that is positioned upstream of a tubular electrode element (18). The outer diameter (226) of the immersion lens cylinder is less than the inner diameter (228) of the tubular electrode element, thereby allowing the downstream end of the immersion lens cylinder to extend into the upstream end of the tubular electrode element. A potential difference applied between the immersion lens cylinder and the tubular electrode element accelerates the electrons in the multiple beams and converges them to form an array of crossovers at a plane (64).

Abstract: An electron beam deflection structure (10) of the traveling wave type effectively cancels the longitudinal voltage gradients and the associated electron beam defocusing that are characteristic of such deflection structures. The deflection structure comprises a first helical coil member (48) and a second helical coil member (50) that are coaxial with the longitudinal axis (26) of the tube. Each of the coil members has wide and narrow segments which alternate along the length of the coil in sequence with the turns of the coil. The first coil member has its wide segments (92a) positioned on the bottom and its narrow segment (92b) on top of the coil member. The second coil member has its wide segments (94a) positioned on top and its narrow segments (94b) positioned on the bottom of the coil member. The narrow segments from one of the coil members are interleaved with the wide segments from the other coil member.

Abstract: An acceleration and scan expansion lens system for use in an electron discharge tube provides scan expanion in which the amount of scan expansion provided in the horizontal direction is independent of the amount of scan expansion provided in the vertical direction. In a preferred embodiment, the lens system (10) is employed in a cathode-ray tube (12) which has greater deflection sensitivity in the vertical direction than in the horizontal direction. The lens system includes a mesh electrode structure (62) that has a dome-shaped mesh element (66) which is supported by an electrically connected to a metallic cylindrical support element (70). The dome-shaped mesh element is formed to have a concave surface as viewed in the propagation direction (35) of the electron beam and is of rotationally symmetric shape. The lens system also includes an annular electrode element (64) that has an aperture of elliptical shape and is positioned adjacent the output end of the mesh electrode structure.

Abstract: The present invention constitutes a cursor image (36) for use in graphics imaging systems for providing images with three-dimensional qualities. The cursor indicates position within a three-dimensional space. The cursor comprises a reference symbol (38) located at a reference point (58) on a reference plane (60), a pointer symbol (40) located pointing to the position (42), and a tether symbol (44) connecting the reference symbol and the pointer symbol. The cursor image includes depth cue features which assist the observer in gauging the depth of the position being indicated. The cursor is preferably displayed with a stereoscopic imaging system (10) employing a liquid crystal stereo switch unit (16). In such a system the cursor image is displayed on a cathode-ray tube (12) in left and right perspective projections (46) and (48) of differing binocular disparity which are used by the observer to form a single three-dimensioinal image of the cursor.