JP2621438B2 - Recording signal playback device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for reproducing a recording signal from a recording medium such as a magneto-optical disk.

[Conventional technology]

FIG. 9 is a block diagram of a recording signal reproducing apparatus of this kind described in Japanese Patent Application Laid-Open No. 62-220297 filed by the present applicant. A signal detected from a recording medium by an optical head (not shown) is filtered by a filter circuit 1 to remove unnecessary band noise, amplified by a first-stage amplifier 2, attenuated by an attenuator circuit 3, and further amplified by an AGC amplifier 4. The output of the AGC amplifier 4 is differentiated by a differentiating circuit 5, and the differentiated output is input to a header detecting circuit 6 and an add-on data detecting circuit 7. The two detection circuits 6 and 7 detect information points from the input signal. The header detection circuit 6 detects data of a header portion described below, and the add-on data detection circuit 7 similarly detects data of an add-on data portion. .
The output of the add-on data detection circuit 7 is applied to a pulse generation circuit 8 that removes a pseudo pulse due to noise included in the output and outputs the result.

Although the recording medium has a large number of tracks in the radial direction and a plurality of sectors in the circumferential direction, FIG. 10 shows a recording format of one sector. The header section A comprises a sector mark recording area 11 for synchronizing each sector, and an address recording area 12 for specifying a track and a sector.
The add-on data section B includes an area 13 for recording a flag indicating whether or not this sector has been recorded, an area 15 for recording data, and an automatic phase control circuit for extracting a clock component from the data recorded in the area 15 (see FIG. (Not shown) and a preamble recording area 14 for performing frequency pull-in and phase pull-in in a short time. Generally, the preamble is recorded at the maximum frequency of the frequency components in the data.

Immediately before the header section A and immediately after the add-on data section, there is a gap section 16 in which no data is recorded.

The header section is information relating to the recording medium itself and is recorded in advance, whereas the add-on data is additionally recorded by this apparatus as needed. Since the detection signals obtained from the header section A and the add-on data section B generally have different frequency components in each part and thus have different levels, the attenuator amount setting signal is given to the attenuator circuit 3 so that different attenuation is provided between the two. And AGC
An AGC control signal is input to the amplifier so that the output becomes constant when the detection signal from the head unit A is input.

FIG. 11 shows the relationship between these signals. The AGC control signal is at the L level only when the header section A is detected and reproduced, and the amplification of the output is constant. The attenuator setting signal is set to Ah (dB) during detection and reproduction of the header section (A) so that the amplitude of the output from the attenuator circuit 3 falls within a predetermined range.

Next, the operation of the circuit of FIG. 9 will be described. A detection signal from a recording medium (not shown) is filtered to remove noise components in unnecessary bands by a filter circuit 1, amplified by a first-stage amplifier 2, and attenuated by an attenuator circuit 3. The output of the attenuator circuit 3 has an amplitude level determined by an appropriate attenuator amount setting value Ah, Ad according to each position of the recording location.

This output is amplified by the AGC amplifier 4, but the header A
When the AGC control signal is applied so as to keep the signal amplitude constant, the signal amplitude of both the header section A and the add-on data section B is optimized by the operation of the AGC control signal and the attenuator circuit 3. For example, FIG. 12 shows an example of the input waveform on the inner track of the recording medium, and FIG. 13 shows an example of the output of the AGC amplifier 4 of the detection signal of the inner track of FIG.

The output of the AGC amplifier 4 is differentiated by a differentiating circuit 5 and input to a header detecting circuit 6 and an add-on data detecting circuit 7.
FIG. 14 shows the input / output of the differentiating circuit 5 and the outputs of the header detecting circuit 6 and the add-on data detecting circuit 7. The information points in the header section A are both edges of the detection signal, and the rising and falling edges are obtained as upward and downward protruding ends at the output of the differentiating circuit 5. The first and second compare levels X and Y are set in the header detection circuit 6, and a rising and falling rectangular wave pulse is obtained as an output when the first and second comparison levels X and Y are exceeded. This is a signal as if the output of the AGC amplifier 4 was shaped.

On the other hand, the information point of the add-on data section B is at the peak of the detection signal waveform, and the add-on data detection circuit 7 has set a third comparison level Z which is close to the peak of the output of the differentiating circuit 5. Outputs the quantified pulse signal. The pulse generation circuit 8 removes a pseudo pulse due to noise from the output of the add-on data detection circuit 7.

In general, since the recording density of the header portion A is low, there is no interference with the recording of adjacent pits. Therefore, the amplitude of the detection signal is constant from the inner circumference to the outer circumference as shown in FIG. Add-on data unit whereas CAV (C onstant A ngular V el
Since the recording medium is rotated at (ocity), the recording density on the inner peripheral side becomes dense, and the amplitude of the detection signal of the maximum frequency component becomes smaller inside the recording medium due to waveform interference. The setting of the attenuator amount setting signal is changed according to the track address so as to compensate for this.

[Problems to be solved by the invention]

In the recording signal reproducing apparatus as described above, the header A
And the reproduction of the add-on data section B is only considered, and the reading of the control track PEP (Phase Encoded Part) data recorded on the recording medium of the ISO standard being determined is not compensated with sufficient accuracy. . The control track is set on the inner or outer periphery of the recording medium to record various data necessary for reproducing the recording medium itself. Therefore, the data reading of this control track should be performed first in the system operation. At this stage, the characteristics of the recording medium are unknown, so that the track cannot be tracked, and the recording medium is focused. However, the output signal amplitude is expected to fluctuate greatly due to the eccentricity of the medium and the recording format is different from the data recording track. There is.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a recording signal reproducing apparatus capable of accurately detecting and reproducing both control track (PEP) data and recorded data.

[Means for solving the problem]

According to the recording signal reproducing apparatus of the present invention, the AGC amplifier is set to the sample mode or the hold mode when reproducing the control track (PEP), and the AGC amplifier is reset, sampled, and held when reproducing the data recording track.
Mode. In this case, if no data exists in the detection signal, the sample mode is prohibited.

[Action]

At the time of reproduction of the control track, the sample mode with data is set, that is, the gain is controlled so that the output of the AGC amplifier is set to a predetermined set value, and the hold mode without data is set as the mode for holding the immediately previous gain. The amplification of the detection signal at the time of control track reproduction is made constant.

Further, when reproducing the data recording track, by setting the reset mode in the gap portion, that is, the mode in which the gain of the AGC amplifier is set to a predetermined value, the reproduction of the sector mark is facilitated. In the sample mode, the hold mode can be used in other parts, and the amplification of the detection signal can be adjusted to a certain value or more, thereby improving the signal reproduction accuracy.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

First, the format proposed as an ISO standard will be described. FIG. 1 is a format diagram of a control track (PEP), in which a data section 21 in which a control track is recorded and a non-data gap section 22 are provided alternately. FIG. 2 is a format diagram of a data recording track, comprising a header section A and a recording data section B, between which a data-free gap section 23 is provided. The header section A includes a sector mark 11, VFO124, address 12, VFO225, and address 12, and the add-on data section B includes a flag 13, VFO326, and data 15.

FIG. 3 is a block diagram showing a main part of the device of the present invention.
A signal detected from a recording medium by an optical head (not shown) is filtered by a filter circuit 1 to remove unnecessary band noise, amplified by a first-stage amplifier 2, further attenuated by an attenuator circuit 3, and then amplified by an AGC amplifier 4.

The output of the AGC amplifier 4 is differentiated by a differentiating circuit 5, and the differentiated output is input to a header detecting circuit 6 and a recording data detecting circuit 7. Both detection circuits 6 and 7 detect information points from the input signal. The header detection circuit 6 detects data in the header section A, and the recording data detection circuit 7 detects data in the recording data section B. The output of the recording data detection circuit 7 is applied to a pulse generation circuit 8 which removes a pseudo pulse due to noise included in the output and outputs the result. A control unit 9 controls the AGC amplifier 4 in three modes of a reset mode, a sample mode, and a hold mode using the output of the AGC amplifier 4 as a feedback signal.

FIG. 4 shows the configuration of the AGC amplifier 4 and the control unit 9. The output of the AGC amplifier 4 is input to a VFO position detection circuit 91, a no-signal detection circuit 92, and a gap detection circuit 93. VFO position detection circuit 91 VFO1 (24), VFO2 (25 ), when it detects the VFO3 (26) for outputting a signal b ₁ which becomes "L" level. The no-signal detection circuit 92 outputs a signal b ₂ which becomes “L” level when there is no detection data.
Is output. The gap detection circuit 93 is provided for the gaps 22, 23.
And it outputs a signal b ₃ which becomes "L" level when it detects.
These signals b ₁ , b ₂ , b ₃ are input to the control circuit 94. The control circuit 94 also receives a control track read command signal a given from a control circuit (not shown), and outputs 2-bit control signals C ₁ and C ₂ for mode control of the AGC amplifier 4.

FIG. 5 shows an example of the configuration of the control circuit 94. In the figure, reference numerals 94a and 94b are selectors, and the input terminals A of the selectors 94a and 94b are fixed at "L" or "H" level, respectively.
Signals b ₁ and b ₃ are applied to an input terminal B, and a selection terminal S
Are supplied with a control track read command signal a. The output Q of the selector 94a are input to the AND gate 94d through an inverter 94c, and the other input of the AND gate 94d and the signal b _3. The output of the AND gate 94d is a NAND gate
The output Q of the selector 94b is input to the NAND gate 94e.
and outputs as a control signal C ₂ together has become another input of e. The output of the NAND gate 94e is output as a control signal C _1. The selectors 94a and 94b connect the input terminal A when the control track read command signal a is at "L" level (when there is a control track read command), and when the control track read command signal a is at "H" level (when there is a record data read command). Input terminal B is selected.

Table 1 shows, for example, the relationship between C ₁ and C ₂ and the control mode of the AGC amplifier 4.

Next, the operation of the signal reproducing apparatus of the present invention will be described.
FIG. 6 is a time chart at the time of reading the control track. When the signal a becomes "L" level, the selectors 94a and 94b output "L" and "H", respectively. Thus the signal C ₂ is always the "H" level [Figure 6 (d)] whereas, signal
C ₁ will be dominated by signal b ₃ .

FIG. 6 (a) schematically shows the recording format of the control track (PEP). When the gap section 22 is reproduced, the input of the AGC amplifier 4 does not appear, and when the data section 21 is reproduced, the input signal is as shown in FIG. An output waveform corresponding to the presence or absence of data is obtained. This is detected by the no-signal detection circuit 92, and the signal
b ₂ becomes “H” or “L” according to the output of the AGC output amplifier 4.
Figure 6 corresponds to the signal C ₁ as shown in (c) is (represented by S) "L", depending on whether the data signal data portion 21 from the "H" sample mode, hold mode (Represented by H) is repeated (FIG. 6 (e)). Therefore, the output of the AGC amplifier 4 can make the amplitude of the detected signal substantially constant as shown in FIG.

Next, the reproduction of the data recording track (a = “H”) will be described. FIG. 7 is a time chart when there is a record in the add-on data section (B). Selector 94a the signal a is at "H" level, 94b are all of the signal b _1, b _2, b ₃ are involved in the mode decision from B pin input is selectively outputted.

First, as shown in FIGS.
Reproducing the 23 signal _{b 2, b 3 "L"} , Figure 7 because signal b ₁ becomes "H" (e), the signal C _1, C _2, as shown in (f) "H" ,
It becomes "L", and becomes the reset mode (R) as shown in FIG. 7 (g), and the AGC amplifier has a predetermined gain. Next, in the sector mark section 11, the signals b ₂ and b _{3 change} to the “H” level, so that the signals C ₁ and C ₂ are both at the “H” level, and the hold mode (H) is set. Then signals C _1, C ₂ since signal b ₁ becomes the VF01 parts 24 turns to "L" level is "L", an "H" level,
The mode becomes the sample mode (S). Address section 12 and VFO
Although the parts are repeated, the hold mode and sample mode since the signal b ₁ is "H" in order to repeat the "L", signal C ₁ Accordingly the "H", changes to "L" level Is repeated.
Then, the gap section returns to the reset mode. During this time
The amplitude of the reproduced signal of the VFO section and the address section becomes substantially constant due to repetition of sample / hold (FIG. 7 (R)). FIG. 7 (h) shows the AGC amplifier 4 input.

By the way, the recording data portion (B), which is appropriately recorded, is a low-level signal compared to the header portion (A) which is recorded in advance when the recording medium is created (FIG. 7 (h)). Signal b ₂ because there is recorded data in the flag 13 of such recording data unit B becomes high level. Therefore, at this time, the signals C ₁ and C ₂
Are both at the “H” level, and the mode is the hold mode. Therefore, this flag is reproduced with the gain in the reset mode. Then the gain becomes VF03 26 by the signal C ₁ and the signal b ₁ turns to "L" level to "L" level and the sample mode is increased in Figure 7. And data 15
In will hold mode with the change of "H" level signal b _1. Accordingly, the recording data is amplified with a gain determined in the sample mode of VF03, and the output of the AGC amplifier 4 has an output amplitude of a predetermined value.

FIG. 8 is a time chart when there is no recording data. In this case, the hold mode “H” is maintained because the signal b ₁ remains at the “H” level in the recording data section B. Others are the same as those in FIG.

〔The invention's effect〕

As described above, according to the present invention, the control track and the data recording track (header part and recording data part)
In both cases, it is possible to obtain a reproduction signal having a level equal to or higher than a certain value, and it is possible to correspond to an ISO standard recording medium.

In the above example, there are two gaps in one sector as shown in FIGS. 7 and 8, so that the reset mode can be obtained twice. However, the gap is only one just before the sector mark. The same effect can be obtained even if the reset mode is performed once. That is, the reproduction level of the flag is only controlled by the level of the address.

[Brief description of the drawings]

FIG. 1 is a recording format diagram of a control track,
FIG. 2 is a recording format diagram of a data recording track, FIG. 3 is a block diagram of the device of the present invention, FIG. 4 is a block diagram of a control unit of the AGC amplifier, FIG. 7 and 8 are time charts for explaining the operation of the apparatus of the present invention, FIG. 9 is a block diagram of the conventional apparatus, and FIG.
10 and 11 are recording format diagrams of a conventional add-on disk, FIG. 12 is an input signal waveform diagram of an AGC amplifier, and FIG.
FIG. 14 is an output waveform diagram, FIG. 14 is an explanatory diagram of information points, and FIG. 15 is a graph showing a level of a detection signal. 9: control unit, 91: VFO position detection circuit, 92: no-signal detection circuit, 93: gap detection circuit, 94: control circuit, 94a, 94b: selector The same or corresponding parts are shown.

Claims (3)

(57) [Claims] 1. A recording signal reproducing apparatus for amplifying a signal detected from a recording medium having a control track on which data relating to signal reproduction is recorded by an AGC amplifier and converting the signal into a digital signal. Means for setting the sample mode to control the gain so that the output of the AGC amplifier is set to a predetermined value when data is present in the signal obtained, and setting the gain of the AGC amplifier to the value immediately before the data no longer exists when no data is present. And a means for setting a hold mode. And a control track for recording data relating to the signal reproduction, a header section for recording information on a recording medium, and an add-on data section for recording data. Each has an AGC amplifier for detecting an analog signal detected from a recording medium having a VFO section in which information relating to signal reproduction is recorded, and a data recording track having a gap section between a header section and an add-on data section. In a recording signal reproducing apparatus for amplifying and converting to a digital signal, when reproducing the data recording track, when the gap is detected, a means for setting a gain of the AGC amplifier to a predetermined value and a reset mode; and Means to set the sample mode to control the gain so that the output of the AGC amplifier is set to a predetermined value if detected, and in other cases Recording signal reproducing apparatus characterized by comprising a means for the hold mode set to a value immediately before the gain of the AGC amplifier. 3. The recording signal reproducing apparatus according to claim 2, further comprising means for prohibiting the sample mode from being set when it is detected that no data exists in the add-on data section.