US 6,587,248 B1Granted

Optical modulator

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorTakaaki Gyoten

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Abstract

A light modulation apparatus using a light source and a device for ON/OFF control an output light of the light source is provided. The apparatus is capable of increasing the number of gradations of light outputted from the device without increasing the frequency of a clock signal that serves as a unit for ON/OFF controlling the output light from the light source. A light intensity modulation circuit generates, based on a luminance signal YS and a synchronizing signal, an intensity modulating signal for output to a power supply, thereby causing a light source to output light intensity-modulated according to the luminance signal. A pulse-width modulation circuit generates, based on the luminance signal YS, the synchronizing signal, and the clock signal, a pulse-width modulating signal for output to a light valve, thereby causing the light valve to output light modulated in pulse width according to the luminance signal.

Claims6

Dependent claims

An optical modulation apparatus for outputting light having a luminance according to a luminance signal, said apparatus comprising:

a light-emitter operable to emit light;
a light intensity modulator operable to control, based on the luminance signal, an intensity of the light emitted from said light-emitter;
and
an ON/OFF controller operable to carry out ON/OFF control of the light from said light-emitter based on the luminance signal, a synchronizing signal, and a clock signal, and to output light having a luminance according to the luminance signal,
wherein, said light intensity modulator is operable to cause said light-emitter to output light at a predetermined intensity, when a value of said luminance signal is not less than a predetermined value, while said ON/OFF controller is operable to output the light at an amount according to the intensity of the luminance signal, and
wherein said light intensity modulator is operable to cause said light-emitter to output light at an intensity that is smaller than the predetermined intensity and is in accordance with the luminance signal when the value of the luminance signal is less than the predetermined value, while said ON/OFF controller outputs light at predetermined amount.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/868,100Filed 8 Aug 2001
Priority: JP 11-29330715 Oct 1999
Granted: 1 Jul 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G09G 3/3406
By control of light from an independent source: control of illumination source
G02F 1/1336
Structural association of cells with optical devices, e.g. polarisers or reflectors: illuminating devices
G02F 1/1347
Constructional arrangements; Manufacturing methods: arrangement of liquid crystal layers or cells in which the final condition of one light beam…
G09G 3/2025
Using sub-frames: the sub-frames having all the same time duration