Dynamic information storage or retrieval – Signal processing by storage and subsequent retrieval
Reexamination Certificate
2001-09-19
2003-12-02
Edun, Muhammad (Department: 2655)
Dynamic information storage or retrieval
Signal processing by storage and subsequent retrieval
C369S059220, C369S124070
Reexamination Certificate
active
06657939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technical field of a signal delay apparatus, a leakage signal removing apparatus and an information processing apparatus. More specifically, the present invention relates to a technical field of a signal delay apparatus for controlling delay amounts of detected signals, which are obtained from a plurality of tracks formed on a recording medium, respectively, a leakage signal removing apparatus including the forgoing signal delay apparatus for removing a leakage signal caused by the detected signals of other trucks from any detected signal and an information processing apparatus including the leakage signal removing apparatus.
2. Description of the Related Art
Conventionally, in the case that the information is detected from the truck formed on the recording medium such as an optical disk or the like, an optical beam is irradiated to this truck and this information is detected on the basis of the reflected light of this optical beam from the track.
On one hand, in recent years, narrowing of truck pitch (namely, narrowing of spacing between the trucks, which are adjacently formed) in the trucks on the recording medium is noticeable at the request of improvement of the recording density. However, in this case, if the optical beam is irradiated to the truck, in which the information to be detected is recorded, a portion of a light spot formed by that optical beam on the recording medium is also irradiated on the truck adjoining the truck to be irradiated (namely, the truck which should not be originally irradiated by the optical beam). As a result, there was a case such that the information recorded in that adjoining truck was leaked in its reflection light as so-called cross talk (a leakage signal).
Therefore, conventionally, the above optical beam is divided into three on a flat surface by using a diffraction grating or the like. Then, a central one of them (hereinafter, referred to as a main beam) is irradiated toward the truck to be originally irradiated and other two beams (hereinafter, referred to as a sub beam, respectively) are irradiated to the two trucks adjoining the both sides of the truck to be originally irradiated, respectively. After that, two detected signals to be obtained from the reflection light of the sub beam are subtracted from the detected signals obtained from the reflection light of the main beam, so that the above described cross talk component, which is included in the detected signal obtained from the reflection light of the main beam, is deleted.
In the above case, according to the conventional cross talk deleting system, the main beam and two sub beams are generated by the diffraction grating or the like, so that a line connecting an irradiation center point of respective beams on the recording medium was not orthogonal to a moving direction of respective trucks.
Therefore, according to the conventional leakage signal removing system, the detected signals obtained from the reflection light of one of the sub beams and the detected signals obtained from the reflection light of the main beam are delayed by fixed times, which are different each other. Then, after orthogonalizing the line connecting the irradiation center points of respective beams and the moving direction of respective trucks for processing the signals (i.e., apparently), the two detected signals obtained from the reflection light of the sub beam are subtracted from the detected signals obtained from the reflection light of the main beam, respectively, so as to remove the above described cross talk.
However, according to the above described tendency of narrowing of truck pitch, the spacing between the above main beam and respective sub beams is also apt to be narrowed. Therefore, it is necessary to fix the spacing more exactly and remove the cross talk. On the contrary, if the oscillation wavelength of the semiconductor laser serving as an ejection source of respective optical beams is changed because of alteration of an ambient temperature or the like, the separation condition by the diffraction grating is changed. As a result, the spacing between the main beam and the sub beams subjects to be changed.
In this case, if this spacing is changed, originally, it is necessary to change the delay amount of respective detected signals depending on the change of the spacing. However, as described above, conventionally, the delay amount is always fixed for respective detected signals, so that this involves a problem such that it is not possible to obtain an appropriate delay amount for orthgonalizing the line connecting the irradiation center point of respective beams and the moving direction of respective trucks for processing the signals in response to the oscillation wavelength of the optical beam.
Further, this problem leads to a problem such that it is not possible to appropriately remove the cross talk and the detected signal is generated as the noise by the cross talk remains in the detected signal in association with the information to be detected, so that the information by the use of this detected signal can not be accurately recorded or reproduced.
SUMMARY OF THE INVENTION
The present invention has been made taking the present problems Into consideration, an object of which is to provide a signal delay apparatus capable of calculating an accurate signal delay amount for removing the cross talk even in the case that the irradiation manner of the optical beam such as the beam spacing or the like is changed, a leakage signal removing apparatus capable of more accurately removing the cross talk and further, an information processing apparatus capable of accurately performing the information processing such as recording or playing or the like by the use of the detected signal, from which the cross talk is accurately removed.
The above object of the present invention can be achieved by a signal delay apparatus of the present invention for delaying at least one of a main detected signal, which is optically obtained from a main truck, in which the information to be detected is recorded, or a sub detected signal, which is optically obtained from a sub truck other than the main truck. The apparatus is provided with: a filter device for generating a leakage signal, which is mixed in the main detected signal in association with the information, which is recorded on the sub truck, on the basis of a filter coefficient; a coefficient setting device for generating the filter coefficient on the basis of the main detected signal, of which the leakage signal is removed, and the sub detected signal, and for outputting the generated filter coefficient to the filter device: a delay amount controlling device for controlling the delay amount in the delay of any one of the main detected signal and the sub detected signal on the basis of the change in the filter coefficient, which is generated in a predetermined time period; and a delay device for delaying any one of the main detected signal and the sub detected signal by the controlled delay amount.
According to the present invention, on the basis of the change of a plurality of filter coefficients, the delay amount of respective detected signals is controlled, so that, even if the irradiation manner of the optical beam to be irradiated to respective trucks is changed, it is possible to delay respective detected signals by accurately controlling the delay amount.
In one aspect of the present invention, the signal delay apparatus is provided with a plurality of filter devices for generating the plural leakage signals, which are mixed in the main detected signal, respectively, in association with the information, which are recorded on a plurality of and different sub trucks, respectively, on the basis of the filter coefficient. Further, the coefficient setting device generates the respective filter coefficients, respectively, on the basis of the main detected signal, of which the respective leakage signals are removed, respectively, and a plurality of sub detected signals
Kuribayashi Hiroki
Miyanabe Shogo
Edun Muhammad
Morgan & Lewis & Bockius, LLP
Pioneer Corporation
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