Patent ID: 7242378

Claim:
An image display device for gray-scale expression based on a digital signal of weighted N bits (where N is an even integer larger than three), the image display device comprising: a plurality of pixels arranged in rows and columns; a scanning portion for periodically selecting said pixels in a predetermined manner; and a gray-scale current generating circuit supplying a gray-scale current according to the digital signal to at least one of said pixels selected by said scanning portion, wherein each of said pixels includes: a light-emitting element exhibiting brightness according to a supplied current, and a pixel drive circuit for supplying the current to said light-emitting element, said pixel drive circuit receives the gray-scale current from said gray-scale current generating circuit during a predetermined period selected by said scanning portion, and supplies a current, according to the gray-scale current received during the predetermined period, to said light-emitting element, said gray-scale current generating circuit includes: a bit select circuit receiving the digital signal, and selectively providing one of two sets of (N/2) bits respectively including even-numbered bits and odd-numbered bits among the N bits, and a current supply circuit controlling the gray-scale current at 2 (N/2) levels according to the (N/2) bits provided from said bit select circuit, in each of said pixels, said light-emitting element receives a current according to the gray-scale current according to one of the two sets of (N/2) bits for a first time length, and then receives a current according to the gray-scale current according to the other of the two sets of (N/2) bits for a second time length, and one of the first and second time lengths is twice as long as the other of the first and second time lengths, in accordance with weighting of the digital signal.