Abstract: A high intensity discharge electrodeless lamp having a segmented excitation coil and capacitor configuration offers minimum light obstruction and RF losses while providing maximum impedance matching and heat transfer from the coil to a heat sink. The excitation coil includes at least two pairs of interconnected windings, each pair disposed concentrically in its own plane. The windings are clustered in a toroidal shape, the center of which is positioned to surround the arc envelope of a high intensity discharge lamp containing an ionizable gas activatable by RF energy. The coil windings are of large cross-sectional area and the capacitors have short leads, so as to minimize EMI and power losses and facilitate heat condition to heat sink means. The windings are configured to follow the contours of the magnetic field lines created by current flow through the total coil.

Abstract: This invention relates to a method and apparatus for extracting contour lines from a pattern obtained in image processing. The disclosed method and apparatus makes it possible to obtain the contour lines in real-time and, moreover, can be easily incorporated into hardware. To achieve these objects, a invention applies the simplified discrimination method for selecting pixels, which form the pattern contour, wherein each pixel is examined within groups of pixel, i.e. X-axis and Y-axis groups. The magnitude of a gray level gradient of each pixel is compared with those of neighboring pixels located in either direction of X-axis group or Y-axis. The pixel which has the maximum magnitude of gray level gradient among those of adjacent pixels is discriminated from each group as contour date. This discrimination method is simple and remarkably improved. When contour lines for two groups are combined, the pattern contours can be easily obtained.

Abstract: A helix slow-wave circuit for use in a linear-beam microwave tube device, comprises a first helix formed by a first wire-like member wound in a first sense at a plurality of turns, and a second helix formed by a second wire-like member wound at a plurality of turns in a second sense opposite to the first sense so as to coaxially surround and superpose on the first helix so that the first and second helixes intersect each other at suitable intervals along an axial direction of the helixes. The first helix is fixed to the second helix in at least some of intersecting points between the first and second helixes.

Abstract: An electric lamp for the photopolymerization of dental materials is supplied with constant electric power so that constant light output is obtained. The control circuit used to this end operates with a triac (3) connected between an a.c. voltage supply (2) and the lamp (1), said triac being controlled by signal values stored in a read-only memory of a microprocessor (4). Said stored values are respectively allocated to pairs of instantaneous values of lamp current and lamp voltage, the instantaneous values being detected in each cycle of the a.c. supply voltage and being utilized to address the read-only memory.

Abstract: The invention relates to an electric arrangement for operating a an electric discharge lamp (13) which is connected in series with a coil (14) and a switch (15) to a pulsatory direct voltage source. The combination of the lamp and the coil is shunted by a rectifier. The lamp is shunted by a capacitor (18) and the switch is periodically rendered conductive at an instant when the instantaneous voltage of the pulsatory direct voltage source is between 0.5 and 0.8 times the then required re-ignition voltage of the lamp. The voltage build up across the capacitor (18) after the switch has become conducting causes the lamp to reignite. The luminous efficacy of the lamp is comparatively high.