JP2718100B2 - Optical recording / reproducing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing method capable of recording data in the width direction of an optical tape or reading the recorded data, and in particular, relates to a reading method. And a method for detecting a data clock signal for use.

[Summary of the Invention]

The present invention, for example, scans a laser beam in the width direction of an optical tape via an optical deflector, and records or reproduces information on a track that is slightly inclined with respect to the running direction of the optical tape. In such an optical recording / reproducing apparatus, two reference pit strings serving as clock references for reproduced data are recorded at both ends in the width direction of the optical tape, and a detection signal obtained from the two reference pit strings is recorded. A data clock signal for reading the reproduction data based on the data clock is generated. Therefore, the area of the execution record data on the optical tape can be widened, and at the same time, the recording density can be improved.

[Conventional technology]

For an optical recording / reproducing apparatus using an optical disk having a light-sensitive recording surface as a recording medium, data is recorded or read on an optical tape having a light-sensitive recording surface. A type recording / reproducing apparatus has been proposed.

FIG. 5 is a schematic view of an optical recording / reproducing apparatus using such an optical tape as a recording medium. Hereinafter, an operation of recording and reproducing information on an optical tape by the optical recording / reproducing apparatus will be described. I do.

A laser beam emitted from a laser source 10 such as a semiconductor or a gas laser is applied to a first collimation lens 11.
The light is collimated by the ultrasonic wave deflection signal supplied to the acoustic light deflector 12, and the light is deflected with a required width. Then, the deflected beam light is incident on the deflection beam splitter 14 and the quarter-wave plate 15 via the second collimation lens 13 and is focused on the optical tape 17 via the objective lens 16. Then, by modulating the laser light source 10 with the recording data, pit information is formed on the recording surface of the optical tape 17 and recording is performed.

At the time of reproduction, the laser light reaching the optical tape 17 is reflected so as to have a different light amount depending on the presence or absence of the recording pit,
The reflected light is applied to a quarter-wave plate 15 and a deflecting beam splitter 14.
The pit information is deflected, reflected in the direction of the cylindrical lens 18 and the detector 19, and the recorded pit information is detected.

An optical tape 17 as a medium on which information is recorded or reproduced by such an optical recording / reproducing apparatus is almost the same as a magnetic tape in a conventional magnetic recording system by a capstan and a pinch roller (not shown). It is driven at a constant speed and its relative position with respect to the optical head including the objective lens 16 is determined.

[Problems to be solved by the invention]

By the way, the data recorded on the optical tape 17 is such a dot that large reflected light can be obtained at the light irradiation spot points Q ₁ , Q ₂ ... As shown in the enlarged view of FIG. The recorded data is recorded as information, and the recorded data can be read from a reproduced signal obtained by scanning the dot information. However, a data clock signal for determining the presence or absence of reflection is required at the time of reading the data.

Therefore, a track T scanned in the width direction of the optical tape is usually provided with a preamble area PA in which clock information is recorded at the head of the track T.
The recording pattern is such that a recording data area RA continues.

The clock information recorded in the preamble area PA is detected at the time of reproduction, and is supplied to, for example, a PLL circuit to form a data clock signal for reading. The clock information recorded in the preamble area PA If the number is small, the operation of the PLL circuit becomes unstable, and the occurrence rate of error data at the time of reading is increased.

Therefore, if the preamble area PA is widened so that sufficient clock information can be obtained, there is a problem that the recording area RA is narrowed and the effective recording density of the optical tape is reduced.

Also, in such an optical tape recording method, it is considered that code conversion is performed so that the clock data frequency component is included in the recording data itself, and the preamble area is merely used as an address signal area. If the signal is converted into a digital signal and converted into another code signal in which the digital signal contains many clock signal frequency components, the hole length increases and the recording surface density decreases.

[Means for solving the problem]

The present invention has been made in view of such a problem,
At one end of a track formed in the width direction of the optical tape, a pit row serving as a phase reference of the data clock signal is arranged in the longitudinal direction of the tape, and at the other end in the width direction of the tape, a frequency reference of the data clock signal is provided. A pit train is similarly arranged in the longitudinal direction of the tape and recorded, and a clock signal generator that controls the phase and frequency of the clock signal by a signal detected from the two pit trains during reproduction is provided. I am prepared for it.

[Action]

A data clock signal serving as a read reference signal for recording data is formed based on a phase reference pit located at the head of the recording track and a frequency reference pit located at the end of the recording track. Actual data can be recorded in most areas except for the position, and the effective recording density of the optical tape can be increased.

〔Example〕

FIG. 1 shows a recording pattern of an optical tape 30 reproduced by the optical recording and reproducing apparatus as shown in FIG.

In the optical recording / reproducing method of the present invention, as shown in this figure, tracks T ₁ , T ₂ ,
At the beginning of T ₃ ..., A phase reference pit sequence P ₁ , P ₁ , P ₁ ... For setting the phase of the read data clock is recorded, and each track T ₁ , T ₂ , T _3. .. Are provided with frequency reference pit strings P ₂ , P ₂ , P _2, ... Which similarly set the frequency of the data clock. Then, data D is recorded between these two pit strings.

And when the laser beam is scanned phase reference pit string P ₁ and frequency reference pit train P ₂ is in synchronization with the clock of the recording data processing circuit, which has been recorded along with the data D, in this example It is composed of one piece of pit information.

Further, such a phase reference pit string P ₁ and frequency reference pit train P ₂ is non-reflective group G ₁ stripe along the opposite ends of the optical tape 30A as shown in FIG. 2, it may be a G _2, In this case, when the optical tape 30A is manufactured, it can be recorded in a preformat in advance.

The optical recording / reproducing method of the present invention uses such an optical tape so that when a light beam scans a track during reproduction as described in detail below, first, a phase reference pit train P ₁ (G ₁ ), A signal serving as a phase reference of the read clock can be detected. Next, after reading the data D, a signal serving as the frequency reference of the read clock can be detected in the frequency reference pit train P ₂ (G ₂ ). , A read clock signal can be generated.

FIG. 3 shows a schematic diagram of an optical recording / reproducing method of the present invention, and FIG. 4 shows an explanatory waveform diagram of a read clock signal.

In these drawings, reference numeral 31A denotes a travel guide for the optical tape 30, and the optical device 31 as shown in FIG. 5 is provided inside the travel guide 31A. 32 is a detector for detecting reflected light, and 33 is a head amplifier for RF signals.

34 by molding the waveform of the RF signal reproduced, the first detection signal E ₁ of the portion of the phase reference pit string as will be described later, the second detection signal E ₂ of the portion of the frequency reference pit string separating a reference signal detection circuit and outputting the start signal E _S1 rising at the first detection signal E ₁ is inputted to the oscillator 35 of the start-stop type.

The start / stop type oscillator 35 is composed of, for example, a logic type inverting amplifier 35A (a NAND gate) and a resonance circuit 35B. However, it is not necessary to increase the resonance characteristic Q. The frequency may be controlled. The output of the start / stop type oscillator 35 is a read clock signal.
It is output as DCL and supplied to the frequency divider 36.

The output of the frequency divider 36 is supplied to one input terminal of a phase comparator 37, and the other input terminal of the phase comparator 37 has a second detection signal E ₂ output from the above-described reference signal detection circuit 34.
Is supplied.

The output of the phase comparator 37 controls the resonance circuit 35B of the start-stop type oscillator 35 via a low-pass filter (loop filter) 38 so that the oscillation frequency can be varied.

39 is driven at a particular count output of the output of the divider 36, a gate pulse generator for detecting a second detection signal E _2.

Reference numeral 40 denotes a signal processing circuit of a recording system, which generates recording data and the above-described phase reference pit sequence signal and frequency reference pit sequence signal and supplies them to the optical device 31.

Further, a control signal synchronized with a signal for driving the optical deflector of the optical device 31 is supplied to the gate pulse generator 41,
The detection signal E ₁ by the gate pulse first output from the gate pulse generator 41 is configured to be detected.

Hereinafter, the operation of generating a clock signal for reading data from the above-described circuit will be described with reference to the waveform diagram of FIG.

When a track of the optical tape 30 as shown in FIG. 1 is scanned, a reproduced signal of one track as shown in a waveform (A) is obtained.
RF is output for each scan of each track.

The waveform (A) at a first signal portion a ₁ level is lowered corresponding to the phase reference pit array described above, this signal is shaped to a first detection signal E _1. Then, the reproduction signal of the data area is obtained after the period t _1, part a ₂ level of the last reproduction signal when scanning the frequency reference pit row is reduced is outputted as the second detection signal E ₂ .

First detection signal E ₁ is extracted by a first gate pulse P _W1 outputted from the gate pulse generator 41, the second second detection signal E ₂ is outputted from the gate pulse generator 39
_Is extracted by the gate pulse _PW2 .

The first detection signal E ₁ at the same time stand up start signal E
_{When 1S} is input to the start / stop type oscillator 35,
NAND gate 35A is activated, it starts the oscillation operation of the sinusoidal signal as shown from the point t ₀ in the waveform (B).

The cycle of the oscillation waveform shown in the waveform (B) is set by the resonance circuit 35B so as to be substantially equal to the cycle of the read clock, and a read clock signal DCL is formed. The clock signal DCL is simultaneously input to the frequency divider 36. It is, for example, N pulses (indicated by hatching) reference pulse when the counted P _N is input to the phase comparator 37, a phase difference between the second detection signal E ₂ phi is detected.

When the oscillation frequency of the start / stop type oscillator 35 matches the frequency of the read clock, the phase difference φ of the phase comparator 37 becomes zero, and the frequency division ratio N is determined so that the read clock signal becomes a normal read clock signal. Therefore, the oscillation frequency of the start-stop type oscillator 35 is controlled by the phase difference output of the phase comparator 37 so as to always coincide with the frequency of the read clock.

The second detection signal E ₂ is outputted with a delay after time t ₃ of the reading period t ₂ of the data, for example, the N-1 th frequency divider 36 to the identification data and frequency reference pit row Is supplied to the gate pulse generation circuit 39, and the gate pulse _PW2 for extracting the _second detection signal E2 is supplied to the reference signal detection circuit 34 to prevent malfunction.

Or by an optical recording and reproducing method of the present invention as described above, the read clock signal DCL which is output from the oscillator 35 of the start-stop type, the initial phase by the first detecting signal E ₁ is read data accurately line The frequency of the clock is constantly corrected by the output phase of the _second detection signal E2.

Thus, the phase reference pit array on the optical tape corresponding to the first detection signal E ₁ and second detection signals E _2, by recording only the frequency reference pit array to read data precisely Will be able to

The portion surrounded by the dashed line is a compensation circuit that operates when the phase reference pit string cannot be detected due to some cause (dropout). The output of the detection circuit 42A that detects the phase reference pit string portion Is the PLL circuit 42B
And is controlled to continuously oscillate at the cycle of the phase reference pit train.

When the signal corresponding to the first detection signal E ₁ is not detected by the detection circuit 42A closes the switch 42C at which time, a signal output from the PLL circuit 42B first
And supply as a detection signal E ₁ to the reference signal detection circuit 34, so as to prevent the information of the phase reference is lost by dropouts, etc..

〔The invention's effect〕

As described above, the optical recording / reproducing method of the present invention forms an optical tape such that a phase reference pit row and a frequency reference pit row are added before and after data at both ends in the width direction of the optical tape. Is reproduced from the two pit strings, a read clock signal is generated from the two pit strings. Therefore, especially in a recording / reproducing apparatus of an optical tape having a short track length, a data recording area is widened. Thus, there is an effect that the effective recording density can be improved.

[Brief description of the drawings]

1 and 2 are diagrams showing a recording pattern of an optical tape applied to the optical recording / reproducing method of the present invention, FIG. 3 is a block diagram for explaining generation of a data clock, and FIG. FIG. 5 is a signal waveform diagram showing the operation of the block diagram of FIG. 3, FIG. 5 is a perspective view showing an example of an optical tape recording / reproducing optical device, and FIG.
The figure shows the recording pattern of the optical tape. In the figure, 30 and 30A are optical tapes, P ₁ and G ₁ are phase reference pit rows, P
_2, G ₂ denotes a frequency reference pit row.

Claims (1)

(57) [Claims] 1. A light beam is scanned in the width direction of an optical tape,
An optical recording / reproducing apparatus for recording and reproducing data, comprising: a phase reference pit array serving as a phase reference of a data clock signal at both ends in a width direction of the optical tape; and a frequency reference serving as a frequency reference of the data clock signal. A pit sequence is formed at the time of recording, and at the time of reproduction of the optical tape, the phase of the data clock signal is set based on a signal that has detected the phase reference pit sequence, and based on a signal that has detected the frequency reference pit sequence. An optical recording / reproducing method, wherein a period of a data clock signal is set.