Sharp Kabushiki Kaisha Corporation

Yutaka Inoue

Masaki Shimizu

Shuhki Ohtani

Takashi Yoshii

Kohji Ohtsuka

Kazuyoshi Izumi

Kazuya Idei

A driving apparatus and a driving method are disclosed that are capable of uniformly lighting each entire fluorescent tube irrespective of the length or number of fluorescent tubes when simultaneously driving a plurality of fluorescent tubes in a fluorescent tube lighting apparatus. When two inverter circuits having respective transformers are provided at both ends of a fluorescent tube to light the fluorescent tube by push-pull driving, feedback windings of transformers not used in self-excited oscillation of each inverter circuit are connected together, with the transformer connection that connects together the feedback windings being either in-phase or in opposite phase, and the method of connection for fluorescent tubes connecting to secondary windings of each transformer can be changed in accordance with that connection method.

Inverter circuit, fluorescent tube lighting apparatus, backlight apparatus, and liquid crystal display

A backlight unit includes a fluorescent lamp to illuminate a liquid crystal panel, a reflection unit for causing the light from the fluorescent lamp to exit toward a certain direction, and a diffusion unit for diffusing the light from the fluorescent lamp and reflection unit, and reflectance or transmittance in the horizontal and vertical directions is controlled by applying a dot pattern that gradually increases densities from the central portion toward the peripheral portion to the reflection unit or diffusion unit, or by applying a dot pattern that gradually increases densities from the central portion toward the both ends in the longitudinal direction on the surface of the fluorescent tube of the fluorescent lamp. By doing this, brightness gradient is formed in the horizontal and vertical directions so that the brightness in the central portion of the liquid crystal panel is relatively higher than the brightness of the peripheral portion thereof.

Backlight unit and liquid crystal display device using the backlight unit

Inverter circuit, fluorescent bulb operating device, backlight device, and liquid crystal display device

A backlight unit includes a fluorescent lamp to illuminate a liquid crystal panel, a reflection unit for causing the light from the fluorescent lamp to exit toward a certain direction, and a diffusion unit for diffusing the light from the fluorescent lamp and reflection unit, and reflectance or transmittance in the horizontal and vertical directions is controlled by applying a dot pattern that gradually increases densities from the central portion toward the peripheral portion to the reflection unit or diffusion unit, or by applying a dot pattern that gradually increased densities from the central portion toward the both ends in the longitudinal direction on the surface of the fluorescent tube of the fluorescent lamp. By doing this, brightness gradient is formed in the horizontal and vertical directions so that the brightness in the central portion of the liquid crystal panel is relatively higher than the brightness of the peripheral portion thereof.

To compensate for uneven brightness in the longitudinal direction of fluorescent lamps of a backlight unit and achieve a display screen with an even brightness, a reflection unit of the backlight unit, the fluorescent tube surface of the fluorescent lamps or a diffusion unit is used to either reduce the reflectance, transmittance, or radiation brightness of the high-voltage side of the fluorescent lamps or increase the reflectance, transmittance, or radiation brightness of the low-voltage side thereof so as to compensate for uneven brightness of the illumination light and thereby ensure an even brightness. For example, dot pattern regions D, Dand D, i.e., the regions whose density increases in stages, are imparted to the portion of a reflection layerof the backlight unit with a relatively high brightness. As for the display device, on the other hand, the display image data supplied to a liquid crystal panel or the aperture ratio of the liquid crystal panel is controlled, for example, to compensate for uneven brightness in the longitudinal direction of the fluorescent lamps and ensure an even brightness.

Growing community of inventors

Mie, Japan

Yutaka Inoue