Sharp Kabushiki Kaisha Corporation

Takashi Iwaki

Hiroshi Fuji

Toshihisa Deguchi

Takeshi Yamaguchi

Tomiyuki Numata

Kunio Kojima

Shigeo Terashima

Tsuneo Fujiwara

Shozou Kobayashi

Shigemi Maeda

Junichiro Nakayama

Tomoyuki Miyake

Katsuo Wada

Miyuki Onishi

Tetsuo Fujiwara

Masaru Nomura

Kentaroh Tsuji

An information reproducing apparatus which has a rotative driver for rotating a disc-shaped recording medium, a floating-type head for reproducing information recorded in the recording medium while floating above the disc-shaped recording medium that is being rotated by the rotative driver, and a suspension, made of an elastic member, for supporting the floating-type head. The information reproducing apparatus is characterized in that the floating-type head has a slider which is floated by an air flow that is directed near the surface of the rotating disc-shaped recording medium, and that the slider has a bevelled portion at one side that faces the outer edge of the disc-shaped recording medium such that any contact between the slider and the ridge that exists along the outer edge area of the disc-shaped recording medium is virtually eliminated. Since the slider is virtually free from contacting the ridge that exists along the outer edge area of the disc-shaped recording medium, the storage capacity of the disc-shaped recording medium can be more effectively used.

Information processing apparatus having a floating-type head

An optical disk apparatus has a galvanic mirror error signal generation circuit for detecting that the galvanic mirror rotates more than an allowed limit value in directions P and Q. When it is detected by the galvanic mirror error signal generation circuit that the galvanic mirror rotates more than the allowed limit value, the light intensity of the light spot is changed from the recording-use (or erasing-use) light intensity into the reproducing-use light intensity. Accordingly, recording and erasing of information is always carried out by the projection of the light beam having a predetermined light intensity, thereby always providing a high grade of optical disk apparatus.

Optical disk apparatus

The first control data generating circuit continuously controls the output light-amount of a light source with respect to an optical disk that has not been formatted. In contrast, the second control data generating circuit controls the output light-amount of the light source at each of a plurality of sectors with respect to an optical disk that has been formatted. A discrimination circuit discriminates whether or not the optical disk has been formatted according to a detection of a header of each sector. According to a result of the discrimination of the circuit, a switch alley switches controlling operations between the first light-amount controlling operation and the second light-amount controlling operation. The difference between those two types of controlling operations merely lies in whether timing for controlling the light amount is dependent on each sector or not. Therefore, independent of whether or not the optical disk has been formatted, the light-amount control device of the present invention makes it possible to determine an optimum output light-amount by using a similar controlling operation.

Light-amount control device for an optical-disk recording-reproduction

An information reproducing apparatus which has a rotating driver for rotating a disc-shaped recording medium, a floating-type head for reproducing information recorded in the recording medium while floating above the disc-shaped recording medium that is being rotated by the rotating driver, and a suspension, made of an elastic member, for supporting the floating-type head. The information reproducing apparatus is characterized in that the floating-type head has a slider which is floated by an air flow that is directed near the surface of the rotating disc-shaped recording medium, and that the slider has a bevelled portion at one side that faces the outer edge of the disc-shaped recording medium such that any contact between the slider and the ridge that exists along the outer edge area of the disc-shaped recording medium is virtually eliminated. Since the slider is virtually free from contacting the ridge that exists along the outer edge area of the disc-shaped recording medium, the storage capacity of the disc-shaped recording medium can be more effectively used.

Reproducing apparatus with suspension supporting a floating-type head

An information recording and reproducing device uses a disk-shaped recording medium which is rotated at a constant angular velocity. The recording medium is divided into a plurality ring-shaped zones of concentric circles. In a recording area of the recording medium, the number of sectors per track is uniform in each zone and the number of sectors increases from an innermost zone towards an outermost zone. Each sector has a header area wherein header information including address information is recorded and a data area wherein data is recorded. In this device, data is recorded and reproduced in the data area in accordance with clock signals whose frequencies increase from the innermost zone towards the outermost zone. This device has a first clock generating circuit for generating a first clock signal of a fixed frequency, and the header information is recorded and reproduced in the header area in accordance with the first clock signal. This device also has a second clock generating circuit for generating a second clock signal having a frequency for recording and reproducing data which varies to correspond to the respective zones, and a control circuit for controlling the frequency of the second clock signal, according to reproduced header information, to correspond to a zone wherein data being recorded or reproduced.

Information recording and reproducing device employing variable data

A track jumping apparatus for an optical disk pickup which can detect a tracking error signal in performing a track jump, and determine a time of acceleration or deceleration of a jump signal by comparing the tracking error signal with a reference level, the track jumping apparatus comprising storing device for storing of standard values corresponding to the kinds of track jumps, standard value selecting device for selecting a standard value corresponding to a kind of track jump in performing the track jump, reference level setting device for setting a reference level so that the ratio of the reference level to a peak value of the tracking error signal agrees with a value based on the standard value selected by the standard value selecting device in performing the track jump, and standard value amending device for amending the standard value in the storing device selected at that moment according to a state of the tracking error signal at the end of the track jump.

Track jumping apparatus for an optical disk pickup

A recording and reproducing device providing control data recording area on erasable type optical recording medium wherein control data are recorded thereof, characterized in that there is provided a control data recording area forming device for forming control data recording areas having more than two control recording blocks which in turn have more than one recording unit. The control data can be recorded independently. A control data updating device records new control data in the control data recording blocks which were the ones not previously being updated with control data, thereby allowing this device to minimize damage caused by electrical power failure.

Optical recording medium recording and reproducing device

An apparatus for recording and reproducing information on and from an optical disk includes a first control for producing a first control signal for controlling the rotational speed of a rotational driving apparatus, on the basis of the detected radial position; a judging apparatus which judges whether or not the reproduced signals are reproduced from a recorded region of the optical disk; a second control for producing a second control signal for controlling the rotational speed of the rotational driving apparatus, on the basis of the signals reproduced from the disk; and a switch apparatus which switches the circuit so that the rotational driving apparatus is controlled by the first control signal when the reproduced signals are not reproduced from a non-recorded region, and controlled by the second control signal when the reproduced signals are reproduced from a recorded region.

Apparatus for recording and reproducing information on and from an

A semiconductor laser driving apparatus for supplying a driving current to a semiconductor laser device of an optical disk recording and reproducing system, the level of which is changed to adjust the optical output of the laser device to one of plural levels corresponding to positions of an optical disk which is irradiated by a laser beam emitted from the laser device. The apparatus comprises: a current source for sequentially supplying plural reference driving currents having a different predetermined level to the laser device; a monitor for detecting the optical output level of the laser device when each of the reference driving currents is supplied to the laser device; a setting device for setting several optimum values on the basis of the detected optical output levels; a selecting device for selecting one of the several optimum values, depending upon the position of an optical disk where is to be irradiated by a laser beam; and said current source for supplying a driving current for recording information on an optical disk, to the laser device, the level of the driving current corresponding to the selected optimum value.

Semiconductor laser driving apparatus

A beam controller for controlling a semiconductor laser provided in an optical recording/playback apparatus includes first and second current sources for driving the semiconductor laser at a low level (play-back mode) and/or at a high level (recording or erasing mode). The first and second current sources are controlled to have stable power automatically by a first and second auto-power circuits, respectively. The first and second auto-power control circuits include a sample-hold circuit which stores an output signal from a low-pass filter. This enables the beam controller to avoid the transition response problems of the low-pass filter. A switching circuit is also included to select either the stored low-pass filter signal on the present low-pass filter signal.

Beam controller for magneto-optical disc memory system

A beam controller for controlling a semiconductor laser included in an optical recording-play-back apparatus. The beam controller is comprised of first and second current sources for driving the semiconductor laser at a low level during a play-back mode and at a high level during an erasing mode. The first and second current sources are respectively automatically controlled by a first and second auto-power control circuit to provide stable power outputs.

A waveform processing circuit includes a switching circuit having first and second inputs and one output. The first input receives head portions and data portions contained in a reproduced signal from an optical head. The second input receives a level signal representing the level of the head portion or the level of the signal carrying the head portion. The switching circuit is switches between a first state in which the first input and the output are connected, and a second state in which the second input and the output are connected. A control signal producer produces a first control pulse indicating the presence of the data portion. The first control pulse is applied to the switching circuit for actuating the switching circuit to establish the first state when the first control pulse is present, and to establish the second state when the first control pulse is not present, so that the switching circuit continuously produces the signal having a level within the range of the head portion. Thus, no abrupt change caused by transient phenomena will be observed in a high pass filter connected to the switching circuit.

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Nara, Japan

Takashi Iwaki