Abstract: A method and apparatus for recovering the phase of a symbol clock operating at a predetermined symbol rate is described. A modulated RF signal which has been downconverted or a modulated baseband signal is filtered and sampled by a high speed converter. A high speed digital signal processor processes the digitized signal to determine the phase of the symbol clock. The symbol phase is determined independent of carrier phase by repetitively resampling the digitized signal and constructing the histogram for each resample of that signal. By comparing the histograms of each resample the symbol phase may be identified. Using the symbol rate and phase, the signal may be analyzed for carrier phase and frequency errors and modulation accuracy using eye diagrams, modulation trajectories and symbol content.

Abstract: A process is described for electrically interconnecting electronic devices located on a surface through one or more planar linking layers consisting of conductors and dielectrics. A three-step additive process is disclosed for forming each planar linking layer. The process may be repeated in order to form the multiple linking layers required for complex VLSI circuits. Each layer is formed by a three step process of applying a uniform dielectric, removing the dielectric where the interconnections, including vias and lines, are to be made and then selectively depositing a conductor to form the interconnections.

Abstract: An improved method and apparatus for performing operations on mathematical expressions in a data processing device, in which stored menus having labels of operations, performable on mathematical expressions, which are concordant with the syntax of individual expressions, are individually addressed by each expression developed in the data processing device. A selected label from a menu addressed by an expression is employed to perform an operation upon the expression. A change in form of an expression by a label of one menu, for example, selecting a subexpression of the expression, may address another menu. Where more than one menu exists for an expression a menu group is addressed by that expression and one menu of that group is displayed. The displayed menu and/or another menu or other menues from that group may be selected to provide labels for performing operations upon that expression.

Abstract: Several problems of alignment associated with ink-jet printers are alleviated by four aspects. In the first, a reverse bow (B) in the paper (12) is created for printing on single sheets of paper. The reverse bow, which in the transverse axis of the paper, forces the paper flat against the platen (14) by using the paper's own stiffness.In the second aspect, the paper and the carriage (30) are referenced to the same part (the carriage guide (10)). In this configuration, the paper is urged against the underside of the carriage guide off of drive rollers (18), through the reverse bow, and onto the platen, where it is printed. The carriage is referenced to the carriage guide through a slider bump by means of a carriage shaft and gravity.The carraige guide comprises stiff thin sheet metal, which is closely-toleranced and has well-controlled dimensions. Thus, this part is good to reference to, rather than molded-in parts, which are not stiff enough at the required thickness.

Abstract: A control system for guiding a vehicle over a floor. The system includes a narrow length of retroflective tape applied to the floor to define a path, an array of LED-phototransistor sensors to generate light toward the tape and generate sensor output signals proportional to the portion of the sensor fields of view occupied by the retroreflective tape. The output signal of each of the sensors is compared to a stair-step reference signal during a 10 millisecond cyclic time period and a binary output signal for each sensor is generated indicating whether the amplitude of the sensor output signal is above or below the changing threshold reference signal. The binary value of each of the sensor output signals is sampled once each millisecond during the time period and the binary values are combined to generate a byte for each sampling occasion. Each of the bytes corresponds to a location in a lookup table which includes interim vehicle lateral directional and displacement commands.

Abstract: A keypad which prevents electrostatic discharge from occurring in electronic equipment such as printers, computers and the like. The keypad includes a switch mechanism positioned on the circuit board associated with the electronic equipment. Attached to the switch mechanism is an actuating lengthening member of sufficient length to isolate the switch mechanism from electrostatic discharge through the keypad. A light source is also positioned under the keypad and the light source has attached thereto a light conducting lengthening member of sufficient length to isolate the light source from electrostatic discharge through the keypad. A method of preventing electrostatic discharge through a keypad to a circuit board is also disclosed.

Abstract: Method and apparatus for storing accessories inside a printing device, wherein the apparatus includes a storage enclosure, which is secured pivotally to the housing of the printing device, and which is capable of assuming at least one open position and one closed position. The storage enclosure is substantially housed within the carriage swept volume, when it is located in the closed position, without interfering with the path of travel of the carriage assembly, when it is in the open position. A cover protects the inner printing mechanism when the storage enclosure is in the open position. A catch mechanism retains the storage enclosure in stable open and closed positions.

Abstract: A printer is disclosed having an improved paper feed mechanism. The improved paper feed system has a reduced cost and accepts a wide variety of paper types including continuous forms and single cut sheets fed both by hand and from a paper tray. Furthermore, the printer is capable of switching from one paper source to another without requiring the operator to unload and reload paper. The mechanism operates with only two motors and no solenoids. Control over the paper path is maintained by employing the carriage to select the paper path and lift the ball. The printer also has a novel paper sensor.

Abstract: A frequency synthesizer circuit employs a frequency detector that receives a reference frequency signal and a variable frequency signal and that generates a difference output signal after detecting a complete cycle of the one of the reference frequency and variable frequency signals that is of the highest frequency, the difference output signal being a function of the difference between the frequency of the reference signal and the frequency of the variable frequency signal.

Abstract: An apparatus is described for interfacing an automatic board test system to an electronic circuit card. This interface permits short and reliable connections between the test system and electronic components located on the circuit card for the electronic signals which test these components. This apparatus works equally well with vacuum actuated and mechanically actuated systems.

Abstract: An active paper drop mechanism (20) for ink-jet printers is provided. The mechanism comprises a pair of opposed, movable rail members (22) associated with opposed walls (14) of a horizontal-disposed output collection tray (12) for receiving sheets (10) of printed media.In particular, each rail member is provided with return spring (26) that act to maintain the rails in a closed position. In that position, the rails support a sheet of the print medium during the printing operation, thus giving the ink on the previously printed-on sheet (10') time to dry.The rails are provided with a wing member (32) and are pivotally secured (38) in the floor of the output tray, with the pivot point spaced inwardly from the wing member. Downward pressure against the wing member thus causes the rail to rotate outward from its closed position, into a recess (24) provided in the side of the output tray. This provides sufficient clearance for the sheet to drop into the output stack.

Abstract: An improved pattern of lines (26, 28) is placed on a wedged substrate (18) used to locate the focal plane of a scanning projection aligner. This pattern replaces the conventional array of microscopic resolution targets with large regions of microscopic lines and spaces. When printed, in- and out-of-focus conditions are macroscopically apparent due to the presence or absence of photoresist (14). Desired quantities conventionally determined from microscopic data, such as location of the best focus plane, astigmatism, mask-to-wafer parallelism, mirror aberrations and misalignments, are macroscopically determined in accordance with the invention.

Abstract: A cartridge-handling arrangement for selectively transferring a tape cartridge from a fixed store holding a plurality of cartridges in a vertical stack, to a fixed record/playback station. The cartridge-handling arrangement comprises an elevator platform moving between the appropriate store level and the level of the record/playback station and a displacement mechanism for transferring a selected cartridge between the store and the elevator platform and between the elevator platform and the record/playback station. The overall arrangement is such that a selected cartridge is presented to the record/playback station in a horizontal attitude.

Abstract: An apparatus and method are disclosed for transferring information into an integrated circuit over the power supply pins of the integrated circuit. The apparatus and method are used to load a test program into memory of the computer system and the system is caused to execute the test program to verify proper operation of the computer system. The apparatus and method are implemented by converting the information to be loaded into a serial bit stream, using the serial bit stream to modulate the power supply voltage of the computer system. Inside the computer system, the low power supply levels are sensed by a low power supply detection unit an fed to a serial-to-parallel converter where it is converted back into the original information.

Abstract: A fixture is disclosed for connecting circuit cards having electronic components to a board test system. The fixture is vacuum actuated. The test fixture comprises a fixture base and a support assembly. The fixture base comprises a board test system interface, supports, probe plate and electrical connections. The probe plate contains an integral vacuum chamber with molded supports. The support assembly comprises a first seal, a support plate, a second seal, and a third seal. The circuit card is positioned by two tooling pins located in the probe assembly. The card is electrically connected to the test system through a probe, connecting wire, and a scanner pin. Two new seals are disclosed.

Abstract: A printed circuit card includes a modified finger contact spanning two finger contact positions on its edge connector to momentarily short correspondingly adjacent receptacle contacts of a mating receptacle connector when the printed circuit card is either plugged into or removed from the mating receptacle connector.

Abstract: Method and apparatus are provided for moving perforated continuous paper (10) through a dual axis printer (12), with both axes (14, 30) driven, while regulating the feed with the perforations and maintaining a controlled tension (38a) in the paper between the two driven axes. The novel approach in this invention is the addition of a set of spring-loaded friction surfaces (56a-62a), incorporated into a gear transmission (50), which limit the amount of torque which can be transmitted to the unregulated drive axis, with the direct effect of controlling the tension in the paper between the two axes.In order to create this tension, the unregulated axis is driven at a slightly greater speed than the regulated axis (with speed measured in terms of inches of paper per revolution of the driven gear (20)).

Abstract: A reticle design is provided for step and repeat projection aligners which, when patterned on a wafer (10), allows quick macroscopic evaluation of best focus for used in fabricating integrated circuits. The reticle pattern consists of opaque lines and spaces of widths slightly above the resolution limit of the resist/aligner system. The macroscopic determination of best focus, being macroscopically visible, eliminates the need for microscopic determination, thereby providing a quick and easy method. The best focus determination is made by forming an array (22) of resist fields (14') on the wafer, subjecting each field to a different focus and exposure. Upon development, those fields away from the best focus and at the larger exposure doses will be removed, leaving a parabola (24) of fields whose apex (26) is at high exposure. Best focus is the focus setting used to print the row of fields (B) containing the apex.

Abstract: A multi-level reticle is described which comprises a multiplicity of integrated circuit mask patterns. The mask patterns are positioned in separate areas on the reticle.The reticle is adapted to be positioned in a projection stepper apparatus for projection of light through one of the areas of the reticle to project a mask pattern onto a substrate (e.g. a wafer) to form an image. The reticle is also adapted to be rotated about its center in a manner such that each of the other mask patterns on the reticle can be projected onto the substrate in registration with the image formed from projection of the first mask pattern onto the substrate. Typically the separate mask patterns are located in separate quadrants on the reticle when there are three or four mask patterns. When there are only two mask patterns, typically they are located in separate hemispheres on the reticle.

Abstract: A method and apparatus for efficient branching within a central processing unit with overlapped fetch and execute cycles which optimizes the efficient fetching of instructions.