Abstract: A control circuit for a DC/DC converter which includes a main switching element, a sub switching element, and a reactor in order to convert a DC input voltage to a DC output voltage. The control circuit comprises a clock signal generator for generating a clock signal during a blank period in which both the main and sub switching elements are off; a comparator for comparing a reference voltage and a voltage at a connection point between the main and sub switching elements and for outputting a comparison signal indicating a relation of magnitude between the reference voltage and the voltage at the connection point; and an operation mode switching section for monitoring the comparison signal at a timing corresponding to the clock signal in order to detect a voltage state at the connection point, and controlling the sub switching element in accordance with the voltage state.

Abstract: To provide a switching regulator with a small packaging area.

Abstract: A toner contains at least a bonding resin and a coloring agent, and has a weight mean particle size from 5 &mgr;m to 12 &mgr;m; not less than 90% by number of particles not less than 3 &mgr;m have a circularity “a” not less than 0.900; a cut ratio Z and a weight mean size X of the toner are related as: cut ratio Z≦5.3×X; and a relationship of particles Y having a circularity of not less than 0.950 and a weight mean size X is Y≧e5.51×X−0.645 where X is 5 to 12 &mgr;m.

Abstract: Coarsely crushed toner particles comprising at least a binder resin and a colorant are effectively pulverized by a mechanical pulverizer including a generally cylindrical rotor rotating about an axis and a stator surrounding the rotor with a minute gap from the rotor. Each of the outer wall of the rotor and the inner wall of the stator is provided with a plurality of grooves which extend generally in parallel with the rotation axis of the rotor and are formed of a wave-shaped plurality of projections and intervening recesses. Each recess on at least one of the rotor and the stator is provided with a flat-shaped bottom between a forward corner and a rear corner adjacent a forward slope and a rear slope respectively, with respect to the rotation direction.

Abstract: A toner manufacturing method includes grinding and classification to produce a toner containing a binder resin and a colorant with a weight mean particle size of 5 microns to 12 microns and sharp particle density distribution. The toner has a specific circularity, relationship between cut ratio and weight mean size, and relationship between circularity and weight mean size as disclosed in the specification.

Abstract: A boosting and step-down switching regulator includes one error amplifying circuit, and an output of the error amplifying circuit is compared with a triangular wave for boosting and a triangular wave for step-down different in voltage level from each other but synchronous with each other in comparison circuits, respectively, to switch the boosting operation and the step-down operation over to each other. Thus, the boosting operation and the step-down operation can be readily switched over to each other irrespective of an input voltage and an output voltage.

Abstract: A toner has toner particles containing at least a binder resin, a colorant and a sulfur-containing compound selected from the group consisting of a sulfur-containing polymer and a sulfur-containing copolymer. The toner has a weight-average particle diameter of from 5 &mgr;m to 12 &mgr;m, and the toner has, in its particles of 3 &mgr;m or larger in diameter, at least 90% by number of particles with a circularity of 0.900 or higher, and has a specific relationship between the cut rate Z and the toner weight-average particle diameter X and a specific relationship between the number-based cumulative value Y of particles with a circularity of 0.950 or higher and the toner weight-average particle diameter X. Also disclosed are an image-forming method and a process cartridge which make use of the toner.

Abstract: A toner contains at least a bonding resin and a coloring agent, and has the following characteristics (i) to (iv):

Abstract: A boosting and step-down switching regulator includes one error amplifying circuit, and an output of the error amplifying circuit is compared with a triangular wave for boosting and a triangular wave for step-down different in voltage level from each other but synchronous with, each other in comparison circuits, respectively, to switch the boosting operation and the step-down operation over to each other. Thus, the boosting operation and the step-down operation can be readily switched over to each other irrespective of an input voltage and an output voltage.

Abstract: A process for producing polymerized toner comprises polymerizing a composition containing a polymerizable monomer and a colorant in a medium to form colored resin particles, separating the particles from the medium by filtration, and drying the separated particles. The separation of the particles from the medium is effected by a decanter-type centrifugal separator equipped with an outer rotary cylinder which contains a screw conveyor freely rotating relative to the cylinder.

Abstract: Coarsely crushed toner particles comprising at least a binder resin and a colorant are effectively pulverized by a mechanical pulverizer including a generally cylindrical rotor rotating about an axis and a stator surrounding the rotor with a minute gap from the rotor. Each of the outer wall of the rotor and the inner wall of the stator is provided with a plurality of grooves which extend generally in parallel with the rotation axis of the rotor and are formed of a wave-shaped plurality of projections and intervening recesses. Each recess on at least one of the rotor and the stator is provided with a flat-shaped bottom between a forward corner and a rear corner adjacent a forward slope and a rear slope respectively, with respect to the rotation direction.

Abstract: A toner has toner particles containing at least a binder resin, a colorant and a sulfur-containing compound selected from the group consisting of a sulfur-containing polymer and a sulfur-containing copolymer. The toner has a weight-average particle diameter of from 5 &mgr;m to 12 &mgr;m, and the toner has, in its particles of 3 &mgr;m or larger in diameter, at least 90% by number of particles with a circularity of 0.900 or higher, and has a specific relationship between the cut rate Z and the toner weight-average particle diameter X and a specific relationship between the number-based cumulative value Y of particles with a circularity of 0.950 or higher and the toner weight-average particle diameter X. Also disclosed are an image-forming method and a process cartridge which make use of the toner.

Abstract: A pulse frequency modulation type DC-DC converter has first and second voltage level comparators for controlling the frequency of a control signal used to drive an output coil. The first voltage comparator detects a first voltage level and the second voltage comparator detects a second voltage level. A reference voltage circuit produces reference voltages corresponding to the first and second voltage levels and provides the reference voltages to the first and second voltage comparators, respectively. An oscillating circuit generates the control signal under control of the first and second comparators. The control signal has one of a first pulse width and a second pulse width depending upon outputs of the first and second voltage comparators for controlling a switching device used for driving an output coil. The switching device is turned on to drive the output coil during a first pulse width when the first voltage comparator detects that the output voltage coincides with the first voltage level.