Patent ID: 9159272
Filing Date: 2015-10-13
Classification: G02F,G09G,H05B

Abstract:
1. A light emitting device for image display that is disposed in an image display apparatus which displays an image based on image data, the light emitting device for image display comprising: a light emitting unit that is divided in a plurality of areas and each of a plurality of light emitting elements configured to emit light in accordance with a current supplied is disposed corresponding to each of the areas; and a Pulse-Width-Modulation (PWM) control portion that applies PWM control to the current supplied to the light emitting element; the light emitting device for image display uses the light emitting element to emit light that is used for display of the image; the light emitting device for image display includes: a control condition setting portion that decides and sets, in an updatable manner, a PWM limit condition and a reference current value in accordance with an Average Picture Level (APL) of the image data; a PWM value calculation portion that calculates a PWM value for each of the areas based on the image data, the PWM limit condition and the reference current value; and an LED control signal generation portion which outputs an LED control signal; wherein the PWM limit condition is a limit value defining an upper limit value of a sum of the PWM values for the plurality of areas, the PWM limit condition is a condition which sets a predetermined limitation on a PWM value which is a duty ratio for the PWM control; the reference current value is a value of a current that flows in the light emitting element in accordance with turning-on of the PWM control; the PWM control portion performs the PWM control based on the reference current value and the calculated PWM value; and the LED control signal contains information about the PWM value for each of the areas, the reference current value, and a set LED voltage value to the light emitting unit.