Abstract: A method of producing a light conductive plate type light source, at least one light diffusing plate and a light reflecting plate are placed on the opposite illuminating surfaces of a light conductive plate in the overlapped state, and subsequently, a plurality of fixing members are press-fitted into the light conductive plate through the light diffusing plate and/or through the light reflecting plate with the aid of supersonic vibration applied to each fixing member. Thus, a securing operation can be achieved for the light conductive type light source at a remarkably improved efficiency regardless of the number of light diffusing plates to be placed on the light conductive plate in the overlapped state. In addition, the light conductive type light source can be produced at a reduced cost because no double-sided adhesive tape is required, and moreover, no supersonic welding operation is performed for each plate.

Abstract: In the revolution frequency indication apparatus in which the revolution frequency of a rotating body is measured and indicated according to a sensor pulse obtained from a revolution sensor mounted on said rotating body or its surrounding, a revolution frequency indication apparatus comprising an indication updating time counter circuit which counts predetermined indication updating time intervals, and a revolution frequency measurement portion which measures the revolution frequency of said rotating body by means of a sensor pulse entered within a measurement time interval of said counter circuit.

Abstract: An inverter apparatus for converting a direct current which flows through the primary side of an output transformer to an alternating current which is outputted from the secondary side of the transformer. Switching elements are used to interrupt the flow of the direct current through the primary of the output transformer and frequency control means is provided for driving the switching elements at the resonant frequency of the resonant circuit formed by the secondary of the output transformer and the load. A circuit for altering the pulse width of the output signal is also provided for controling the power delivered to the load.

Abstract: A power source device for driving a liquid crystal device comprises an inverter for powering a back-light discharge lamp and a negative voltage power source generator for driving the liquid crystal device. The negative voltage generator is provided as part of the inverter. A step-up transformer of the inverter is commonly used as part of the negative voltage power source generator.

Abstract: A liquid crystal display apparatus has a back illuminating device which is so arranged that a light emission area of a fluorescent lamp is positioned externally of a reflector, and a light guide is integrally provided at an end thereof with a folded or bent portion, an incident portion at the end of the folded or bent portion extending to that light emission area of the fluorescent lamp which is positioned externally of the reflector, to thereby guide light to a dial or indicator on the light guide.