Minebea Company, Limited

Mitsuo Matsushima

Kohei Nishibori

Hiroshi Shinmen

Shinichi Suzuki

To provide a discharge lamp lighting device in which the initial state of discharge in a wiring of a circuit on the secondary side of a transformer in the discharge lamp lighting device is accurately detected and the operation thereof stops and which can be applied to a large-scaled liquid crystal display device. The discharge lamp lighting device according to the present invention includes a transformer, a transformer drive circuit, and a control circuitfor controlling the transformer drive circuit. The transformer drive circuitdrives the primary side of the transformer, and a discharge lampis lit on by being connected to the secondary side of the transformer. The discharge lamp lighting device further includes a discharge detecting patternhaving one end connected to the ground and the other end connected to the control circuit, and means that detects a voltage induced by electromagnetic waves received by the discharge detecting patternand stops the power supply to the secondary side of the transformer, and at least one part of the discharge detecting patternis disposed adjacent to a portion of a high-voltage wiring of a circuit on the secondary side of the transformer

Discharge lamp lighting device

There is provided a discharge lamp lighting apparatus including common lines to which the low voltage side outputs of step-up transformers having a plurality of discharge lamps connected thereto are connected, wherein the low voltage side outputs connected to the common lines include two kinds of outputs in an equal number at which respective lam currents are phase-shifted by 180 degrees from each other. The discharge lamp lighting apparatus further includes: malfunction detecting circuits which is composed of sense resistors to sense the lamp currents synthesized on the common lines and comparators to compare with a sense voltage with a predetermined reference voltage, and which outputs a malfunction detecting signal when the sense voltage exceeds the reference voltage; and a protection circuit to stop driving of bridge circuits according to the malfunction detecting signal.

Discharge lamp lighting apparatus

There is provided a discharge lamp lighting apparatus including a dimmer circuit which is provided with a control means to dynamically adjust screen brightness according to an input signal, and a control means to adjust screen brightness based on a user's operation. The dimmer circuit includes: an amplitude adjusting circuit to superpose a first dimming control signal composed of a DC voltage onto a second dimming control signal composed of a pulse width modulation signal; an integration circuit to integrate an output of the amplitude adjusting circuit; and a comparison circuit to compare an output of the integration circuit with a triangular wave having a predetermined frequency thereby generating a dimming signal, wherein a burst dimming mode is performed according to the dimming signal.

Dimmer circuit for a discharge lighting apparatus

A discharge lamp lighting apparatus includes a transformer defining primary and secondary sides; a transformer driving circuit to drive the primary side of the transformer thereby lighting a discharge lamp connected at the secondary side of the transformer; a control circuit to control the transformer driving circuit; a high voltage capacitor formed of a pattern capacitor and disposed between one terminal of the secondary side of the transformer and the discharge lamp; and a discharge detecting pattern disposed close to the high voltage capacitor. In the discharge lamp lighting apparatus, a voltage induced in the discharge detecting pattern is duly detected, and power supply to the secondary side of the transformer is stopped.

A discharge lamp lighting apparatus is provided for lighting a plurality of discharge lamps including one reference lamp and at least one controllable lamp. First variable inductance element and lamp current detecting unit are connected to the reference lamp, second variable inductance and lamp current unit are connected to the controllable lamp, and a lamp current controlling circuit is connected to each of the first and second variable inductance elements. An output signal from the second lamp current detecting unit and also an output signal as a reference signal from the first lamp current detecting unit are connected to the lamp current controlling circuit for the controllable lamp, whereby the lamp current of the controllable lamp is controlled. The reference output signal is also connected to a control circuit, and the lamp currents of the reference and controllable lamps are controlled further by the on/off operation of the switching elements.

Discharge lamp lighting apparatus for lighting multiple discharge lamps

In a discharge lamp lighting apparatus to light two discharge lamps, one terminal of the secondary side of a step-up transformer is connected to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamps is connected, via each of two variable inductance elements, to one lamp current detecting unit, a signal of each lamp current detecting unit is connected to a lamp current control circuit, and an output signal from each lamp current control circuit is connected to each variable inductance element so as to vary the inductance of each variable inductance element, whereby the lamp current flowing through each discharge lamp is controlled.

In a discharge lamp lighting apparatus to light two discharge lamps, one terminal of the secondary side of a step-up transformer is connected, via each of two variable inductance elements, to one terminal of each of the two discharge lamps, the other terminal of each of the two discharge lamp is connected to one lamp current detecting unit connected to a lamp current control circuit, a switch is provided at the previous step of the lamp current control circuit, an output signal from one phase adjusting circuit is connected, via the switch, to the connection portion of the lamp current detecting unit and the lamp current control circuit, and the inductance of each variable inductance element is varied by an output signal which is sent from the lamp current control circuit, and which has a phase shifted from others, whereby the lamp current flowing through each discharge lamp is controlled.

A discharge lamp driving apparatus comprises a DC power supply, a control circuit, switching elements, a step-up transformer, and a lamp current controlling circuit. In the discharge lamp driving apparatus, the secondary side of the step-up transformer is connected to multiple discharge lamps respectively via variable inductance elements, a series resonant circuit is constituted by a capacitor provided between the variable inductance element and the discharge lamp, leakage inductance of the step-up transformer, and inductance of the variable inductance element, and an output of the lamp current controlling circuit is connected to the variable inductance element, wherein the inductance of the variable inductance element is varied thereby controlling the lamp current of the discharge lamp.

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Kitasaku-gun, Japan

Mitsuo Matsushima