Abstract: In a capacitor charging system having multiple rectified outputs of secondary (transformer) windings, the rectified outputs are connected in parallel for enhanced charging of an energy-storage capacitor below a threshold voltage, and are connected in series above the threshold voltage. In the parallel mode, forward biased diodes connected from rectifier-to-rectifier effect the parallel connection. In the series mode, a switch closure effectively connects the rectifiers in series, which reverse biases the diodes. For switching two or more rectified outputs, the number of switch closures required is one less than the secondary windings. Multiple windings (and rectifiers) can be paired and switched, and two or more thresholds can be employed.

Abstract: In a preferred embodiment, a method of of of determining if a compound diffraction grating has been forged, the compound diffraction grating including a plurality of diffraction grating elements of different types, the compound diffraction grating being read by serially detecting light diffracted by the diffraction grating elements, including: determining the amplitude of diffracted light signals as the compound diffraction grating is being read; and determining that the compound diffraction grating is forged if the amplitude is below a selected threshold level. In another aspect of the invention, there is provided a method determining if such a diffraction grating has been forged, the method including: measuring the number of transitions between diffraction grating elements across the strip; and comparing the number with a pre-recorded number of the transitions and determining that the diffraction grating strip has been forged if the numbers are not the same.

Abstract: In one preferred embodiment, a memory device for insertion and retention in a hole defined in a planar identification card having upper and lower surfaces, the memory device comprising: electronic circuitry disposed in a cylindrical housing having upper and lower surfaces; the housing being held substantially within the hole after being snapped thereinto; and the housing having a total height substantially the same as the thickness of the card. In a further aspect of the invention, electronic circuitry in the housing is accessible by temporary attachment to an electronic terminal, the electronic circuitry being powered by a charged capacitor, the capacitor being adapted to be charged by the terminal with a charge sufficient to power the electronic circuitry for only a selected period of time. The capacitor may be charged over a communication line to the memory device. The memory may be disabled if a use limitation stored therein is exceeded.

Abstract: A method and apparatus for causing a message sent in facsimile compatible form over a telephone system from a first location to a second location to be received at the second location in a confidential manner such that only the intended recipient may view the message when he so desires. The intended recipient is notified when a facsimile message has been received for him and the recipient may retrieve the facsimile message remotely.

Abstract: There is provided, in one preferred embodiment, a bar code reader which has a variable scan angle, with the amplitude of the scan angle initially being relatively small and then increasing in magnitude until a bar code is read. As the amplitude of the scan angle increases, the scan frequency is decreased, thereby keeping the scan rate across the bar code relatively constant. Consequently, for example, a high-density bar code may be read at either a close distance or a far distance without sacrificing resolution. Additionally, the reading of a selected bar code in the presence of other, closely-spaced bar codes is facilitated. In another preferred embodiment, the scan frequency is held constant and the clock rate in the bar code reader is increased with increasing amplitude of the scanning angle.

Abstract: In a preferred embodiment, a method of limiting access to computer systems which method includes scrambling identification card information with time information so that the resulting code can be used for only a limited period of time, thus preventing unauthorized persons from using the code at a later time. In another aspect of the invention, one or more .mu.-metal shields are embedded in an identification card, thus identifying the card as being valid and also providing means to indicate when a valid card is being removed from a card reader.

Abstract: A bar code reader head having an optical block with cavities formed therein into which various optical elements may be placed without the need for any adjustment thereof. A first illumination source, producing any desired spectrum of light, illuminates at least a portion of the bar code. A second illumination source may be provided to produce a second spectrum of light. Reflected light passes through a lens in front of which is an aperture slit parallel to the bar code bars. A channel is formed between the lens and a photodetector perpendicular to the light path. If both visible and infrared illumination sources are used, visible light is focused at the side of the channel toward the lens and infrared light is focused at the other side of the channel. In the channel is a template having at least one discriminator slit parallel with the slit in front of the lens. The width of the discriminator slit depends upon the widths of the bars to be read.

Abstract: A compression refrigeration system having means to pass the low pressure gas from the evaporator in heat exchange relationship with the high pressure liquid passing from the condenser to the expansion valve. The low pressure gas is passed in heat exchange relationship around the external casing of the receiver/drier, to maintain the receiver/drier at a lower temperature, assist in ensuring that the low pressure gas does not contain any unvaporized liquid, and to cool the high pressure liquid before passage to the expansion valve.

Abstract: A compression refrigeration system having means to pass the low pressure gas from the evaporator in heat exchange relationship with the high pressure liquid passing from the condenser to the expansion valve. The low pressure gas is passed in heat exchange relationship around the external casing of the receiver/drier, to maintain the receiver/drier at a lower temperature, assist in ensuring that the low pressure gas does not contain any unvaporized liquid, and to cool the high pressure liquid before passage to the expansion valve.