Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
2001-09-19
2004-10-12
Hindi, Nabil (Department: 2653)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
C369S124110, C369S044320
Reexamination Certificate
active
06804187
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 foregoing 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, 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 orthogonalizing 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 any one of detected signals, which are optically obtained from a plurality of adjoining trucks. The apparatus is provided with: an extracting device for extracting a specific main detected signal having a predetermined specific waveform from a main detected signal which is obtained from a main truck among said trucks; a holding device for holding a sub detected signal which is obtained from a sub truck when said specific main detected signal is extracted; an averaging device for averaging a plurality of said sub detected signals, which are held by said holding device during a predetermined time frame, and generating an averaged detected signal; a calculating device for comparing a waveform of said generated averaged detected signal with said specific waveform and calculating the delay amount for any one of said detected signals; and a delay device for delaying at least any one of said detected signals by said calculated delay amount.
According to the present invention, the delay amount of at least any one of detected signals is calculated by comparing a waveform of an obtained averaged detected signal and a specific waveform, 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 calculating the delay amount.
In one aspect of the present invention, said specific waveform comprises a zero cross waveform.
According to this aspect, the delay amount is calculated by using a zero cross waveform as a typical specific waveform, so that it is possible to simply and accurately calculate the present delay amount.
In another aspect of the present invention, said specific waveform is provided with a waveform of said main detected signal, which is obtained from any one of a pit formed on said main truck in association with said information and a gap between pits, having a length which is longer than the length obtained by multiplying a unit length of at least any one of said pit and gap by a predetermined number.
According to this aspect, a waveform of the main detected signal, which is obtained from
Kuribayashi Hiroki
Miyanabe Shogo
Hindi Nabil
Morgan & Lewis & Bockius, LLP
Pioneer Corporation
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