Patent ID: 7358937

Claim:
A display reading apparatus including devices to display or read images in units of pixels, each pixel comprising: a first transistor to drive the relevant device; a current supply circuit for supplying, in a first mode, a current of a magnitude based on the value of the pixel displayed by said device; a second transistor whose control electrode is connected to the control electrode of said first transistor to thereby constitute a current mirror circuit in combination with said first transistor, wherein said second transistor receives, in the first mode, the current supplied from said current supply circuit; a capacitor connected to the control electrode of said second transistor and holding, in the first mode, the voltage generated in the control electrode of said second transistor in a state where the current supplied from said current supply circuit is received; a first switch changed when enabling said device to receive the light; a second switch for connecting, in a second mode, the device to said first transistor in a state where the voltage generated in the control electrode of said second transistor and held in said capacitor is supplied to the control electrode of said first transistor; a third switch changed in a third mode for holding, in said capacitor, the voltage generated in the control electrode of said first transistor in a state where the current to flow in said device is supplied; and a fourth switch for outputting, in a fourth mode, the current to flow in said second transistor in a state where the voltage generated in the control electrode of said first transistor and held in said capacitor is supplied to the control electrode of said second transistor.