Patent ID: 7071611

Claim:
A display panel, comprising: a first optically transparent electrode layer; a second optically transparent electrode layer; a conductivity-variable layer provided on the first optically transparent electrode layer; and an electroluminescent layer provided between the conductivity-variable layer and the second optically transparent electrode layer, which emits light by applying a voltage thereto; a predetermined voltage being applied between the first optically transparent electrode layer and the second optically transparent electrode layer, and the conductivity-variable layer having its electrical conductivity changed in accordance with a light quantity of control light transmitted through the first optically transparent electrode layer; and the electroluminescent layer emitting the light so that the voltage in the predetermined voltage as corresponds to the conductivity of the conductivity-variable layer, is applied thereto when the conductivity of the conductivity-variable layer has been changed in accordance with the light quantity of the control light transmitted through the first optically transparent electrode layer.