Patent ID: 7773470
Filing Date: 2010-08-10
Classification: G11B

Abstract:
1. A pickup control device comprising: a circuit which processes a first signal for error control to generate a servo control signal, the first signal being read from an optical disk; a clock signal generator which generates a clock signal synchronized with a rotation of the optical disk; a first memory and a second memory each of which is controlled by use of the clock signal synchronized with the rotation of the optical disk generated by the clock signal generator and stores one of a frequency component contained in the first signal and a rotational frequency component contained in the first signal, the frequency component being equal to or lower than a predetermined frequency; a first adder which adds data from the first memory to the first signal; a second adder which, in synchronization with the clock signal, retrieves data from the first memory and the second memory and accumulates those data to generate a second signal; and a difference correction data generating part which controls generation of a difference correction data in response to a change in a rotational frequency of the optical disk by, in a first period in synchronization with the clock signal, writing a current data on one of the frequency component and the rotational frequency component into the second memory, in a second period that is synchronized with the clock signal and is subsequent to the first period, reading out past data stored in the first memory to supply the read past data to the second adder, and writing again into the first memory the second signal generated by the second adder to update past data stored in the first memory as the difference correction data, and which, in a third period that is synchronized with the clock signal and is subsequent to the second period, reads out the difference correction data from the first memory to supply the difference correction data to the first adder.