Canon Kabushiki Kaisha

Tsukasa Ogino

Hisatoshi Baba

Nobuyuki Tonegawa

Hirotake Ando

Yoshihiro Saga

Shigeyuki Taniwa

There is disclosed a network status server for receiving an inquiry from a web server accessed by a client, and using path information and determining the optimum web server to return a response to the accessed web server. The web server receiving the response instructs the client to access the optimum web server from the next time. In this constitution, accesses among the dispersed/arranged web server sites are leveled, and access loads can be leveled even among the web servers in the respective web server sites. Moreover, the client can access the optimum web server.

Network status server, information distribution system, control method, and storage medium for storing control program

An information recording/reproducing apparatus for recording information on and/or reproducing information from a recording medium using a head. The apparatus includes a single processor and a memory device. The single processor executes data input/output processing and servo processing of a light beam from the head, while alternately switching at a predetermined period. The servo processing is divided into a plurality of blocks which are cyclically executed in turn for each predetermined period and processing required to be executed in each period is set in each block and processing not required to be executed in each period is set in only a specific block. The memory device stores contents of the processing for the respective blocks.

Information recording/reproducing apparatus for periodically executing

In an information recording/reproducing apparatus, a head is moved across tracks on a recording medium to thereby perform a coarse seek to a position near a target position. A recording/reproducing portion of the head is moved in the track intersection direction to thereby perform a fine seek to the target position. A moving velocity of the portion of the head with respect to the medium is detected by a first detector. A target moving velocity is caluculated in accordance with a remaining distance to the target position of the portion of the head. A moving displacement or moving velocity of the portion of the head is detected by a second detector. A detection value from the first detector is corrected on the basis of a detection value from the second detector to eliminate a variation component generated by a disturbance of the portion of the head.

Information recording and/or reproducing method and apparatus in which

Input/output processing of information is controlled in a magnetooptical disc apparatus for recording and/or reproducing the information on a magnetooptical recording medium by irradiating a desired track of the recording medium with a light beam via an optical system. The servo control of the light beam such as tracking servo control, focusing servo control or the like is performed by causing interruption in the input/output processing control. When the apparatus activates, a parameter in the servo control is set on the basis of a reproduction signal amplitude of the information with a change in state of the servo control and a parameter in signal processing of the information is set in accordance with a reproduction signal amplitude of the information corresponding to the set parameter for the servo control.

Magnetooptical disc apparatus having single micro-processor for

An information recording/reproducing apparatus includes an optical system, a moving device for moving a light beam in a direction to cross tracks on a recording medium by moving the optical system, and a tracking error signal detector for detecting a tracking error signal indicating a tracking error of the light beam. In the apparatus, a time interval that the tracking error assumes a predetermined value is detected. A current velocity of the optical system is obtained every time point that the tracking error assumes the predetermined value on the basis of the measured time interval and a moving distance of the optical system corresponding to the time interval. A target velocity value of the optical system is generated at the next occurrence timing of the predetermined value of the tracking error signal upon detection of the current velocity value. An acceleration value of the optical system is generated using the current velocity value and the target velocity value. The moving device is controlled on the basis of the acceleration value.

Information recording/reproducing apparatus with function of seeking

An information recording and/or reproducing apparatus includes a head for effecting information recording on and/or information reproduction from a recording medium. The head is moved to a desired track on the recording medium by a driving device. A tracking error signal of the head, generated when the head is moved by the driving device is detected. At every predetermined period of the tracking error signal, the head drive velocity is calculated from a distance corresponding to the predetermined period and a time corresponding to the predetermined period. The calculated velocity is corrected on the basis of an acceleration of the head and a time period during which the acceleration is applied, so that the driving device is controlled by use of the corrected drive velocity.

Information recording/reproducing apparatus in which a control value for

An automatic loop gain control apparatus in a servo control apparatus of a closed loop arrangement which positions a control object with respect to a reference. The apparatus includes an adder for adding a reference signal of a predetermined frequency to a control signal in the closed loop, a first detector for detecting a peak value of predetermined frequency components of the control signal in a state before the control signal is input to the adder at every predetermined cycle, a second detector for detecting a peak value of predetermined frequency components of an output output from the adder at every predetermined cycle, and a digital signal processor for performing a digital computation using the peak value detected by the first detector and the peak value detected by the second detector and for adjusting the gain of the control loop on the basis of the result of the computation.

Automatic loop gain control apparatus

An optical information recording/reproducing apparatus for recording and/or reproducing information on and/or from an optical memory medium includes an optical system for forming a light beam spot for recording and/or reproducing information on and/or from the optical memos medium, a signal generating unit for detecting a position of the optical system relative to the medium and generating an analog signal corresponding to the detected position, an actuator for driving the optical system, an A/D converter for converting the analog signal from the signal generating unit into a digital signal, a digital signal processing unit for calculating a control amount of the actuator on the basis of a predetermined control process in order to correct the relative position from an output from the A/D converter, and a D/A converter for converting the output from the digital signal processing unit into an analog signal. The actuator is driven in correspondence with the output from the D/A converter. The control process of the digital signal processing unit can be arbitrarily changed.

Optical information recording/reproducing apparatus comprising digital

In an information recording/reproducing apparatus, a recording/reproducing head is moved across tracks on a recording medium by a linear motor which is controlled to effect a seek operation of the head to a target track. A CPU for controlling the apparatus judges the seek direction of the head and whether the seek distance of the head is equal to or greater than a predetermined distance, in conformity with a recording or reproduction command from a host controller on the basis of a logical address designated by the host controller and a logical address at which the head is positioned. When the seek distance is equal to or greater than the predetermined distance, the linear motor is activated in the seek direction. Then, the logical address designated by the host controller is converted into a physical address and a control is effected such that the head reaches the target track.

Information recording and/or reproducing method and apparatus including

The present invention provides an optical information recording and reproducing apparatus wherein a light beam spot is properly illuminated onto a recording medium by detecting a tracking error signal and/or a focus error signal in a time shared mode and by activating a tracking actuator and/or a focus actuator, thereby performing the recording and reproducing of information. The apparatus of the present invention includes a device for approximating an error signal on the basis of a plurality of error signals previously detected, when an error signal cannot be detected during an error signal detecting operation.

Optical information recording and reproducing apparatus that

An information recording/reproducing apparatus is provided with a velocity control device for moving a recording and/or reproducing head from a current track to a target track under velocity control. A target velocity for the head is determined and the moving velocity of the head is detected by a detector. An instruction value for an actuator for moving the head is generated at every predetermined calculating interval on the basis of the target velocity and the detected velocity so that the head follows the target velocity. In the generation of the instruction value for the actuator for the head, the calculating interval can be switched into plural values by a switching device until the head reaches the target track.

Information recording/reproducing apparatus

An optical information recording and reproducing apparatus for effecting at least one of recording of information on and reproducing of information from a recording medium. The apparatus includes an optical system for applying a light beam to a desired track on the recording medium, a tracking and focusing error detection device for detecting tracking and/or focusing error of the light beam relative to the track, a computing unit for (i) receiving respective tracking error and focusing error output signals from the detecting device, (ii) effecting a computation for a selected output signal among the received output signals on the basis of a predetermined program to correct the detected tracking error and focusing error, (iii) calculating tracking and focusing control movement amounts and (iv) outputting a tracking control signal and a focusing control signal corresponding to the tracking control movement amount and the focusing control movement amount, respectively. The apparatus also includes a tracking actuator for moving at least a portion of the optical system to move the light beam relative to the track on the basis of the tracking control signal, and a focusing actuator for moving a portion of the optical system relative to the recording medium to adjust a focusing state of the light beam on the basis of the focusing control signal.

Optical information recording and reproducing apparatus including a

An information recording-reproducing apparatus in which the seeking operation of an information recording/reproducing head is effected while controlling the velocity of the head. The head is moved by a linear motor in a direction to traverse the tracks provided on a recording medium. During the movement of the head, a tracking error signal is generated and is detected. The moving velocity of the head is detected at every predetermined period. The linear motor is controlled in synchronization with the velocity detection so that the head moves in conformity with a predetermined target velocity on the basis of the detected moving velocity.

Information recording and reproducing apparatus and method in which an

An apparatus for recording and/or reproducing information with respect to a disk-like recording medium having a recording surface divided into a plurality of concentric circular zones each including a plurality of tracks with an address recorded thereon at an angular velocity or frequency varying with the individual zones, includes, a device for scanning the tracks for recording and/or reproducing information, a device for detecting an address of a track being scanned by the recording and/or reproducing device, a device for shifting the recording and/or reproducing device from a track being scanned to another track, and a control device for determining, if an address of a desired track cannot be detected when accessing the desired track during shifting of the recording and/or reproducing device to a zone different from a zone to which the desired track belongs, and shifting, as a result, the recording and/or reproducing device to a different track.

Method for accessing desired track on disk with plurality of recording

An information recording and/or reproducing apparatus includes an optical system for irradiating a light beam to one of tracks arranged in parallel on a recording medium, an actuator for moving the optical system across the tracks, a circuit for alternately applying a jumping signal and a braking signal of the opposite polarity to the actuator to direct the light beam to a desired track, a tracking signal detector for intermittently sampling a tracking error signal varying between a positive value and a negative value with the movement of the optical system across the tracks, a memory for storing the sampled signals, and a switching timing detector for multiplying or adding the sampled signal and the previously sampled signal stored in the memory and causing the signal application circuit to switch from the jumping signal to the braking signal when the product or sum is zero or negative.

Growing community of inventors

Yokohama, Japan

Tsukasa Ogino