Abstract: The present invention is a method and apparatus for organizing memory buffers between an i/o subsystem and a computer system. The present invention organizes the memory buffers that exist between a computer system and an associated i/o subsystem into a memory hierarchy. An example of such a hierarchy includes, in order, a disk buffer, a disk cache, a controller memory and a computer system memory. Each datablock in the memory hierarchy is given an associated index word. The index word contains the address of the datablock within the media of the disk drive and contains index bits which indicate where the datablock may be found in the memory hierarchy. As a datablock moves between the disk drive and the computer system, a mirror copy of the datablock is maintained in a memory buffer that is in the next adjacent level of the memory hierarchy. In this way, the mirror copy may be used if the datablock becomes inaccessible.

Abstract: A switch mode power converter achieving high efficiency through zero voltage switching (ZVS) by using an auxiliary switch, a capacitor, an auxiliary winding and an inductor. The technique can be applied to a boost, buck-boost, buck, isolated forward or isolated flyback converter. The auxiliary switch is turned on before the main power switch turns on, and the capacitor provides voltage to energize the inductor and force current to flow into the auxiliary winding. The current is transformed by the main winding and discharges the capacitance across main power switch to zero volts before the main switch turns on. Hence ZVS is obtained and can greatly reduce the switching loss of the main power switch.

Abstract: An AC-to-DC power converter draws input current through an inductor. When the input voltage of the converter is sufficiently high and the switch of the converter is on, current flows into the converter, through the inductor, to the tap of a transformer, through a first primary winding of the transformer, and through the switch. When the switch is then turned off, current continues to flow through the inductor and to the tap of the transformer but then flows through a second primary of the transformer and into a storage capacitor. Energy stored in the storage capacitor is transferred to the load when it is not possible to obtain sufficient energy from the input current to supply the load. The AC-to-DC converter has very few circuit components and low input current harmonics.

Abstract: A switch mode voltage regulator with synchronous rectification that produces ripple cancellation with fast load response is described. The switch mode voltage regulator comprises a main step-down regulator with synchronous rectification with an auxiliary step-down regulator that produces an output ripple cancellation current that is equal but opposite to the output ripple of the main regulator during static load conditions. During changing load conditions a feedback control circuit changes the duty cycle of the main regulator while a time-delay circuit prevents a change of the duty cycle in the auxiliary regulator. Thus, the main regulator is allowed to change its average current while preventing a counteracting average current change in the auxiliary regulator. An embodiment is described in which the duty cycle in the auxiliary regulator is changed in phase with the duty cycle of main regulator to further improve the dynamic response to load changes.

Abstract: A buck converter in accordance with the present invention provides multiple, well regulated, low voltage outputs. A cascaded buck converter comprises a main buck converter that is coupled to a subordinate buck converter through a cascade transistor in series with the free wheeling diode or transistor. The main buck converter is coupled to the free wheeling diode through the cascade transistor. Additional voltage outputs are possible by placing additional subordinate buck converters in series with the cascade transistor.An isolated forward converter with multiple output voltages in accordance with the present invention may be derived using the cascaded buck converter topology. The cascading configuration permits multiple voltage outputs using a minimum number of switching devices while avoiding undesirable cross regulation.

Abstract: A switch mode power converter achieving high efficiency through zero voltage switching (ZVS) by using an auxiliary switch, a capacitor, an auxiliary winding and an inductor. The technique can be applied to a boost, buck-boost, buck, isolated forward or isolated flyback converter. The auxiliary switch is turned on before the main power switch turns on, and the capacitor provides voltage to energize the inductor and force current to flow into the auxiliary winding. The current is transformed by the main winding and discharges the capacitance across main power switch to zero volts before the main switch turns on. Hence ZVS is obtained and can greatly reduce the switching loss of the main power switch.

Abstract: A light pen computer interface system utilizes a coil located externally of the computer's CRT display monitor to sense the magnetic field which provides the raster for the CRT. Vertical and horizontal sync detection circuits receive the sensor coil output and supply vertical and horizontal sync signals to a timing circuit. The timing circuit in response to an output signal from the light pen and the vertical and horizontal sync signals supplies a pen position signal to the computer which is either representative of the x,y coordinates position of the light pen on the CRT screen or representative of the change of x,y coordinates between successive positions of the light pen.

Abstract: A transformer bobbin has margining ledges disposed on either side of a primary winding surface such that a primary wire is wound between margining surfaces of the margining ledges. L-shaped grooves extend into the margining ledges and then parallel to the primary winding surface to accommodate the primary wire ends that connect to terminals of the bobbin. Margining of the secondary is accomplished with a pair of margining bibs which attach to the bobbin after the primary is wound and after a layer of insulation is placed over the primary. The secondary is wound over the insulation layer between margining surfaces of the bibs. With the margining ledges and bibs, required creepage distances can be maintained without the use of sleeving, margining tape, interlayer tape or holding tape.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: Method and system for the on-line, real-time collection and processing of bar code data utilizing a bar code data collection network, at least one work station and a host computer having a database, such as a relational database, is provided. Bar code data collection programs can be interactively developed and/or modified from the workstation which is programmed with menu-driven software. Bar code transactions are interactively defined and validated from the workstation.

Abstract: An adapter for use in a computer system having an IDE interface controller and a plurality of drives. The adapter is connected to the IDE controller and the plurality of drives and monitors information transmitted between the IDE interface controller and the plurality of drives. The adapter determines whether each of the plurality of drives is serviceable and whether data on each of the plurality of drives are equal. Identical data is directed to each of the plurality of drives when data on each of the plurality of drives are equal. Data is prevented from being directed to at least one of the plurality of drives when data on each of the plurality of drives are not equal. One of the plurality of drives is selected as a drive from which to read data.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: An inexpensive, compact, portable, retractable cord, visual indicator, electrical/telephone connector-type surge protector, which comprises a housing composed of a molded plastic, with two female receiving grounding inlets on its upper surface, a visual indicator light, and a pair of female telephone inlets on one side. On another side, the housing has two openings for a retractable electrical extension cord and a retractable telephone cord. On the opposite side of the housing are two independent, retaining, on-off switches for the two cords. The housing is composed of two sections, an upper and lower section, with an inner spring coil mechanism on two independent reels in each section for the electrical and telephone cords respectively. The invention is designed to be used with standard electrical apparatus or other sensitive electrical devices, which are to be protected from electrical surges, where extension cords may be required, and allows for the retraction of the cords when not required.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: A boost converter power supply circuit uses energy from a diode recovery current which flows in the blocking diode at diode commutation to discharge a capacitance associated with the main switch of the boost converter in order to achieve zero voltage switching. The diode recovery current energy is initially captured in an inductor, is then transferred to a capacitor, and is then transferred back to the inductor prior to the main switch being switched on. In accordance with another embodiment, a control circuit for controlling a boost converter to achieve power factor correction is disclosed which does not use a high gain input current feedback loop. The control circuit responds relatively quickly to output load changes, thereby overcoming disadvantages of prior art control circuits. Because the control circuit does not require an X-Y multiplier, the control circuit lends itself to realization in integrated circuit form.

Abstract: A two switch, DC/DC converter provides sufficient inductive energy storage at the termination of the "on" period of each switch to alter the charge on the intrinsic and stray capacitance of the combination of switches producing zero voltage across the alternate switch prior to its turn on. A short dead-band between the turn on pulses provided by the control circuit allows time for this transition. Thus the energy stored in the capacitance of the switches is returned to the source and load rather than being dissipated in the switching devices. This greatly improves the efficiency of the converter particularly when operating at high frequency. The unique topology of the converter provides other new and useful characteristics in addition to zero voltage switching capability such as operation as constant frequency with pulse-width-modulation for regulation, quasi-square wave output current, and the ability to integrate the magnetic elements with or without coupling.

Abstract: A two switch, DC/DC converter provides sufficient inductive energy storage at the termination of the "on" period of each switch to alter the charge on the intrinsic and stray capacitance of the combination of switches producing zero voltage across the alternate switch prior to its turn on. A short dead-band between the turn on pulses provided by the control circuit allows time for this transition. Thus the energy stored in the capacitance of the switches is returned to the source and load rather than being dissipated in the switching devices. This greatly improves the efficiency of the converter particularly when operating at high frequency. The unique topology of the converter provides other new and useful characteristics in addition to zero voltage switching capaibility such as operation at constant frequency with pulse-width-modulation for regulation, quasi-square wave output current, and the ability to integrate the magnetic elements with or without coupling.

Abstract: A replaceable seal assembly (10) for a used Canon brand developer station (100) having a peripheral recess (106) created by the removal of the original toner reservoir seal; wherein, the seal assembly (10) having a seal unit (11) including a generally rigid seal member (13) having a generally flexible seal member (14); and, a bracket unit (12) which is adapted to frictionally engage the generally rigid seal member (13) relative to the peripheral recess (106); whereby, the seal unit (11) may be inserted and removed from said peripheral recess (106) in the course of recharging the developer station (100) with fresh toner.