Abstract: An LED drive method drives an LED by a drive current. The LED drive method uses a voltage conversion unit, which includes a coil and a first switch, and converts an external voltage into a first voltage, which is a DC voltage, by controlling the first switch to be on in an on-pulse period of a first drive signal. A constant current drive unit is provided with the first voltage and generates a drive current based on a second drive signal.

Abstract: An LED lighting device 2 according to this embodiment includes a lighting circuit that supplies a current to an LED, and a dimmer 7 that generates a PWM signal for controlling the supply of the current to the LED from the lighting circuit, in which the dimmer 7 feedback-controls the PWM signal that controls the supply of the current to the LED by comparing the output current to be output to the LED with a target current and feedforward-controls the PWM signal according to a fluctuation of an input voltage from a commercial power supply 1.

Abstract: A semiconductor device configured to perform an A/D conversion of a wide range of signals is provided. A semiconductor device includes: an input voltage detection unit configured to detect an analog input voltage; a reference voltage setting unit configured to set a reference voltage based on the detected input voltage; an amplifier configured to amplify a difference between the input voltage and the reference voltage; an ADC configured to perform an A/D conversion of an amplified signal; and an arithmetic processing unit configured to calculate a digital voltage corresponding to the input voltage based on a result of the A/D conversion and the reference voltage.

Abstract: A semiconductor device configured to perform an A/D conversion of a wide range of signals is provided. A semiconductor device includes: an input voltage detection unit configured to detect an analog input voltage; a reference voltage setting unit configured to set a reference voltage based on the detected input voltage; an amplifier configured to amplify a difference between the input voltage and the reference voltage; an ADC configured to perform an A/D conversion of an amplified signal; and an arithmetic processing unit configured to calculate a digital voltage corresponding to the input voltage based on a result of the A/D conversion and the reference voltage.

Abstract: An LED drive method drives an LED by a drive current. The LED drive method uses a voltage conversion unit, which includes a coil and a first switch, and converts an external voltage into a first voltage, which is a DC voltage, by controlling the first switch to be on in an on-pulse period of a first drive signal. A constant current drive unit is provided with the first voltage and generates a drive current based on a second drive signal.

Abstract: A voltage conversion unit including a coil and a first switch converts an AC voltage into a first voltage, which is a DC voltage, by controlling the first switch to be on in an on-pulse period of a first drive signal. A constant current drive unit is supplied with the first voltage and generates a drive current Id having a current value according to light control information. An LED control unit compares brightness based on the light control information and reference brightness, generates a first drive signal based on an error between the first voltage and a target voltage representing a target of the first voltage, when the brightness is higher than the reference brightness, and generates the first drive signal having a predetermined fixed on-pulse period when the brightness is lower than the reference brightness.

Abstract: An LED lighting device 2 according to this embodiment includes a lighting circuit that supplies a current to an LED, and a dimmer 7 that generates a PWM signal for controlling the supply of the current to the LED from the lighting circuit, in which the dimmer 7 feedback-controls the PWM signal that controls the supply of the current to the LED by comparing the output current to be output to the LED with a target current and feedforward-controls the PWM signal according to a fluctuation of an input voltage from a commercial power supply 1.

Abstract: Reduction of flicker when an LED is in a low brightness state and reduction of size of an LED drive device are realized. A voltage conversion unit includes a coil and a first switch and converts an AC voltage into a first voltage which is a DC voltage by controlling the first switch to be on in an on-pulse period of a first drive signal. The constant current drive unit is supplied with the first voltage and generates a drive current Id having a current value according to light control information. An LED control unit compares brightness based on the light control information and reference brightness, generates a first drive signal based on an error between the first voltage and a target voltage representing a target of the first voltage when the brightness is higher than the reference brightness, and generates the first drive signal having a predetermined fixed on-pulse period when the brightness is lower than the reference brightness.

Abstract: A method of longitudinally seam-welding steel pipes comprises the steps of providing a conductive net-like enclosure tube around a cable for supplying a direct electric current from the power source to the welding head; and conducting a direct electric current through the enclosure tube and through the steel pipe in a direction opposite to that in which the direct current runs through the cable. Apparatus for longitudinally seam-welding steel pipes comprises an electrical cable coupled to a welding head, a net tube surrounding the cable, and a device for supplying a direct electric current to the cable in a first direction and to the net enclosure tube and steel pipe in the opposite direction. The direct currents flowing in the enclosure tube and in the steel pipe is adjustably controlled to minimize the magnitude of a magnetic field created around the net enclosure tube and producing a welded steel pipe seam.

Abstract: Circular pipe of large diameter progressively formed of flat stock, the pipe having a single longitudinal seam is seam-welded by preparing welding grooves such that the inner groove is smaller in size and angle than the outer groove, sequentially carrying out submerged arc welding on the inner welding groove, and large current MIG welding to then first layer of the outer welding edge and a submerged arc welding to a second layer thereof.

Abstract: In longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the GMA welding process which comprises using direct electric current supplied to a plurality of consumable electrodes in tandem through at least one cable as the welding current, at least two even-numbered consumable electrodes are used, half of said consumable electrodes being connected to said direct current so as to be positive in polarity and the remaining half of said consumable electrodes being connected to said direct current so as to be negative in polarity, to enable lines of magnetic force produced by said direct electric current for welding flowing through said at least one cable introduced into said pipe-blank to cancel each other, thereby preventing magnetization of said pipe-blank and the resulting magnetic arc blow of the welding arc.

Abstract: In longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the metal arc welding process which comprises using direct electric current supplied to a plurality of consumable electrodes in tandem through at least one current supply cable as the welding current, an even number of consumable electrodes are used; half of said even-numbered consumable electrodes are connected in the reverse-polarity manner, i.e., to be positive in polarity, and are used as leading electrodes, and the remaining half are connected in the straight-polarity manner, i.e.

Abstract: In longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the reverse-polarity GMA welding process comprising using direct electric current supplied to a consumable electrode through a cable as the welding current with said consumable electrode as the anode, the direction of said direct electric current for welding flowing through said cable introduced into said pipe-blank is set in the same direction as that of welding, thereby preventing occurrence of a magnetic arc blow of the welding arc from said consumable electrode toward the upstream side of the welding direction, i.e., in the opposite direction to that of welding.

Abstract: After longitudinally seam-welding a pipe-blank for welded steel pipe from the inside along a groove by the arc welding process which comprises using direct electric current supplied to a consumable electrode through a cable as the welding current, the polarity of said consumable electrode applied for said longitudinal seam-welding is switched over to the opposite polarity, an arc from said consumable electrode is ignited again on a tab plate attached to the end of said pipe-blank on the completion side of said longitudinal seam-welding to cause a direct electric current for eliminating magnetism to flow through said cable in the opposite direction to that of said direct electric current for welding, thereby eliminating residual magnetism in said pipe-blank produced by said direct electric current for welding flowing through said cable introduced into said pipe-blank during said longitudinal seam-welding.

Abstract: In a gas shielded arc welding method for a long seam of formed pipe and the like, an improved method of setting up a welding voltage-current such that incomplete short circuiting transfer is performed with a high speed of more than at least 3m/min. and particularly, 5m/min. or more, without requiring stopping of the arc at short circuiting intervals.

Abstract: A method for coating a paint of high viscosity, wherein the paint is extruded in a filament-like form from a nozzle and is applied to a moving surface in a striped or convoluted pattern, and a gas is blown against the coated surface to smoothen it.