Abstract: The scan direction of at least one scan line is changeable in a scanner for reading bar code symbols by selectively reversing a drive.

Abstract: A laser scanning device for projecting a laser beam against a target having information contained thereon which is to be scanned by the laser beam. The device is in particular a compact bar code reader which incorporates internal unitary structure with a resiliently mounted integral scanning motor for compactly supporting various laser and optics components for modular installation in the device, and which protects at least the integral scanning motor from external impacts and shock loads.

Abstract: A bar code detector or acquisition arrangement for detecting the presence and location of a bar code pattern in a field of view. The bar code pattern detector is not designed to decode a bar code pattern, but merely to be sensitive to and detect the presence of a bar code pattern or patterns so that a conventional bar code scanner can then be activated to perform a decoding operation thereon. The present invention is based upon the generation of Moire patterns, and includes an electro-optic system for detecting and locating a bar code pattern in which an image of a field of view is projected onto a reference bar code pattern or an image thereof while producing relative rotation between the image of the field of view and the reference bar code pattern or image thereof. An optical detector detects the optical interaction of the image of the field of view with the reference bar code pattern or image thereof, including any Moire patterns generated thereby.

Abstract: A hands-free scanning system for reading indicia having parts of different light reflectivity, including a housing having a window and an actuatable electro-optical scanner in the housing for projecting a light beam through the window to indicia to be read, for scanning the indicia. The system further detects light of variable intensity that is reflected off the indicia to generate an electrical signal representative of the indicia. The housing is mounted on an arm of an operator and the scanner initiates reading of the indicia upon movement of the operator's hand relative to the arm by means of an actuator switch.

Abstract: A voltage drive circuit for driving a stepping motor for a laser scanning mirror in a laser bar code reader assembly. The voltage drive circuit provides a highly damped, low q drive in which resonance is virtually eliminated and wherein damping of the rotor is proportional to its angular velocity, and also the position of the rotor precisely follows an input voltage signal driving the motor. The stepping motor includes a rotor, a stator, a center-tapped AC winding and a DC winding. The motor drive circuit comprises a triangular waveform generator for generating a periodic triangular voltage signal. A driving circuit for an AC winding receives the periodic triangular voltage signal as an input, and includes a voltage feedback circuit in which the voltage across the AC winding is compared with and caused to follow the input voltage signal driving the AC winding.

Abstract: A laser-scan bar code reader is mounted in a hand-held unit operable in two modes. In one mode the hand-held unit may be mounted in a fixed position in a terminal in which case the data generated from the bar code reading operation is transferred immediately to the terminal and the reader is powered continuously from the terminal unit. In the other mode, the hand-held unit is separated from the terminal and held manually, in which case the data from bar code reading is stored in a local memory to be later transferred to the terminal when the hand-held unit is again inserted into the terminal. A battery in the hand-held unit is charged when the unit is mounted in the terminal, then powers the hand-held unit while operating remote from the terminal. The power for battery charging and the data transfer are accomplished without direct connections between the hand-held unit and the terminal.

Abstract: An arrangement for reading bar code symbols including a laser diode unit having a forwardly-directed laser beam emitted along an optical path toward a symbol for reflection therefrom to generate reflected light, and a rearwardly-directed laser beam, and a monitor photodiode in optical communication with the rearwardly-directed laser beam for producing a signal indicative of the output power of the laser diode. The arrangement also includes a collector exterior to the laser diode unit for collecting at least a portion of the reflected light from the symbol, and for directing the collected portion to the monitor photodiode to generate an information signal descriptive of the symbol.

Abstract: A bar code scanner employs a light source such as a laser for generating a light beam to be directed along a path toward a bar code symbol to be read. A scanner such as a mirror driven by a motor moves the light beam along a scan line across the bar code symbol. A sensor detects the intensity of reflected light from the bar code symbol, and generates an electrical signal in response to this reflected light. A signal processor receives the electrical signal and produces a digitized signal representing the bar code symbol. Control circuit automatically de-energes the scan by shutting off at least one of the light source and the motor after the signal processor has produced a digitized signal representing a valid bar code symbol.

Abstract: Several embodiments are disclosed of bar code readers in which one or more piezoelectric bimorph elements are utilized as a drive element in the optical system thereof. In different embodiments, the piezoelectric bimorph element is utilized in the scanning function of the bar code reader optical system, or in a variable focus zooming function of the optical system. The bar code readers are provided with improved decoding reliability, speed and orientation freedom, with regular or high density, one or two dimensional bar codes, by using multiple beam symbol crossings, created by using one or more piezoelectric bimorph elements. In different disclosed embodiments, one or more cantilever mounted piezoelectric bimorph elements support a scanning mirror, or a focusing lens, or a laser diode, or a laser diode and limiting aperture, for movement at the free ends of the bimorph elements to produce a scanning of the bar code reader optical system.

Abstract: High speed scanning arrangements in scanners for reading bar code symbols by oscillating a scanner component mounted on an arm of an asymmetrical U-shaped spring in single or multi-axis scan patterns.

Abstract: In a laser scanning system, an automatic gain control (AGC) circuit for dynamically adjusting the gain of a receiver that is used to receive light reflected from a bar code. The AGC provides a fast adjustment to receiver gain so that the receiver can provide a decodable signal quickly. To accomplish the fast adjustment, the AGC circuit, in addition to sensing the final output of the receiver, includes an additional feedback path from an amplifier in the receiver that is located before the final amplification stage. The additional feedback has a negligible attack time, and adjusts receiver gain quickly, thereby minimizing the time required to reach steady state.

Abstract: A system for representing and recognizing data in machine readable graphic image form in which data to be encoded is entered into the system and a processor encodes the data into a two-dimensional pattern of graphic indicia and generates transfer drive signals representative of the indicia. A transferring device such as a printer transfers an image of the two-dimensional pattern of graphic indicia onto a carrier such as a card or paper document in response to the transfer drive signals. A recognition device converts the image on the carrier into electrical signals representative of the graphic indicia and decodes the signals into output signals representative of the data for further processing or use.

Abstract: A laser diode in a scanner is deactuated during part of each scan to conserve power and to increase the working lifetime of the diode and of a battery for powering the scanner. The dead zone in which specular reflection may prevent a successful reading of the symbol is minimized. The scanner includes a head which cannot be disassembled unless an electrical cable connecting the head to the remainder of the scanner is first removed.

Abstract: A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.

Abstract: A portable scanning head emits and receives light from a light-emitting diode to read symbols, such as bar-code symbols. The optics within the scanner are operative for focusing a light beam and the view of a light sensor in different planes exteriorly of a scanner housing. Imaging means are provided in the unit for imaging a viewing window. The viewing window has an area smaller than that of the scan spot. The system can employ an LED as a light source and tolerate the relatively large-sized (on the order of millimeters) scan spot without sacrificing reading performance since the photodiode "sees" only that portion of the scan spot visible through the viewing window.

Abstract: A point-of-sale system includes an infinitely adjustable optical scanner for reading bar code symbols, and a terminal operatively connected to the scanner. A bendable, elongated arm is operative for at least temporarily maintaining the scanner in any selected one of an infinite number of adjusted orientations relative to a work surface over which the symbols pass. A hood is mounted on the scanner for preventing overloading of a scanner photodetector. One scan pattern is selected among a plurality of scan patterns to read the indicia.

Abstract: A portable laser diode scanning head, aimable at each symbol to be read, emits and receives non-readily-visible laser light, and is equipped with a trigger-actuated aiming light arrangement for visually locating and tracking each symbol. A compact laser diode optical train and an optical folded path assembly, as well as an interchangeable component design and an integral window construction for the head also are disclosed.

Abstract: In bar code symbol scanning systems employing laser, optical and sensor components, a mirrorless scanner arrangement mounts one or more of these components on a drive for repetitive reciprocating movement either about an axis or in a plane to effect scanning.

Abstract: A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.

Abstract: The depth of modulation of an analog electrical signal generated by a photodetector during scanning of a bar code symbol in the field of bar code scanning is enhanced under circumstances where the modulation of the analog signal has been degraded, for example, by an oversized sampling aperture in relation to the widths of the symbol elements. The analog signal has high frequency components whose low amplitudes are increased in magnitude prior to being conducted to a digitizer. The effect of noise introduced during reading of the bar code is cancelled by comparing in the comparator, the modulation-enhanced analog signal with the second derivative signal derived from the modulation-degraded unenhanced analog signal. The output of the comparator is a digital output signal having a logical level dependent on the amplitude of the enhanced analog signal at each zero crossing of the second derivative signal. The digital output signal is a closer representation of the code read by the scanner.