Patent ID: 7605411

Claim:
A charge transfer device comprising: a charge transfer path that transfers electric charges; a charge branch path that is connected to the charge transfer path and distributes the electric charges, which are transferred along the charge transfer path, into two directions; first and second branch transfer paths that are connected to the charge branch path and are provided corresponding to the two directions; a plurality of transfer electrodes that are provided above the charge transfer path and are arranged in a first charge transfer direction along which the charge transfer path transfers the electric charges; a branch electrode that is provided above the charge branch path; a plurality of first branch transfer electrodes that are provided above the first branch transfer path and are arranged in a second charge transfer direction along which the first branch transfer path transfers the electric charges; a plurality of second branch transfer electrodes that are provided above the second branch transfer path and are arranged in a third charge transfer direction along which the second branch transfer path transfers the electric charges; and a driving unit that applies voltages to the transfer electrodes, the branch electrode, the first branch transfer electrodes and the second branch transfer electrodes, to drive the charge transfer path, the charge branch path, the first branch transfer path and the second branch transfer path, wherein when the electric charges are transferred from the charge transfer path to the first branch transfer path, the driving unit applies predetermined voltages to the transfer electrodes and the first branch transfer electrodes while applying to the branch electrode a fixed voltage, which is independent from the voltages being applied to the transfer electrodes and the first branch transfer electrodes, so that step-like potentials being contiguous toward a downstream side in the first and second charge transfer directions are formed in a path from the charge transfer path, in which the charges are accumulated, to the first branch transfer path, the charge branch path includes a first portion being connected to the charge transfer path, a second portion being connected to the first branch transfer path and a third portion being connected to the second branch transfer path, and the charge branch path includes a protrusion portion that protrudes inward from at least one of a first outer circumference that connects one of ends of the first portion in a direction perpendicular to the first charge transfer direction and one of ends of the second portion in a direction perpendicular to the second charge transfer direction, and a second outer circumference that connects the other end of the first portion in the direction perpendicular to the first charge transfer direction and one of ends of the third portion in a direction perpendicular to the third charge transfer direction.