Source: {"pile_set_name": "USPTO Backgrounds"}

1. Field of the Invention
The present invention relates to a technology for an imaging device capable of focus detection by a phase difference detecting technique.
2. Description of the Related Art
In an imaging device, such as a digital single-lens reflex camera, focus detection has been suggested using a phase-difference detection technique with an image pickup device (also referred to below as an image pickup device provided with a phase-difference detecting function) with a plurality of pairs of photoelectric converting units (photo diodes), each pair receiving a subject light beam through a pair of partial regions of an exit pupil (for example, right and left pupil portions) to generate an electric charge signal. Examples of this image pickup device are as follows.
For example, Japanese Unexamined Patent Application Publication No. 2001-250931 discloses an image pickup device with a phase-difference detection function, the image pickup device configured to have a two-way split photoelectric converting unit (referred to below as a half-sized photoelectric converting unit) in each normal pixel (each of R, G, and B pixels) for obtaining an image signal of a subject, that is, the image pickup device in which a pair of half-sized photoelectric converting units is disposed on a lower portion of one microlens.
Also, for example, Japanese Unexamined Patent Application Publication No. 2005-303409 discloses an image pickup device with a phase-difference detection function, the image pickup device in which a pair of photoelectric converting units receives light from a pair of partial regions of the exit pupil by restricting subject light beams at a pair of adjacent pixels by an opening formed at a light-shielding mask using a metal layer.