JP2001119655A - Recording system discrimination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording system discrimination device that can discriminate recording system of recording contents, even if the output of a head is decreased due to demagnetization in the case that a frequency-modulated luminance signal of each recording system recorded on a tape of a cassette for each recording system is reproduced. SOLUTION: This recording system discrimination device is provided with a 1st changeover section that selects an output of a 2nd filter section, when an identification result of a cassette for each recording system indicates a 1st recording system or selects an output of a 1st filter section, when the identification result indicates a 2nd recording system and with a 2nd changeover section that controls inversion of an output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a recording system discriminating apparatus in a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art In recent years, a first recording system such as a VHS system (a trademark of Victor Company of Japan, Ltd.) and a second recording system such as an S-VHS system (a trademark of Victor Company of Japan, Ltd.) exist. Conventionally, there are many tapes recorded by the first recording method on the first recording method cassette. on the other hand,
There are many tapes recorded by the second recording method in the cassette for the second recording method. There are also tapes recorded on the second recording-method cassette by the first recording method.

Recently, as an optional standard for the second recording system, tapes recorded by the second recording system on the first recording system cassette have come to appear. For this reason, importance has been placed on the discrimination of the recording system when reproducing the tape of the cassette.

Hereinafter, a conventional recording method discriminating apparatus will be described with reference to the drawings.

FIG. 3 is a block diagram showing a configuration of a conventional recording method discriminating apparatus. 3, reference numeral 1 denotes an input terminal for inputting a frequency-modulated luminance signal reproduced from a video head, and 2 denotes a horizontal retrace period extracting unit for extracting a horizontal retrace period portion from the frequency-modulated luminance signal from the input terminal 1. Is the frequency of the horizontal retrace period portion of the first recording method in the output of the horizontal retrace period extraction unit 2, for example, 3.8 MHz in the PAL method.
a first filter unit that passes only near z, and near 3.4 MHz in the NTSC system, 6 is a level detector that detects the output level of the first filter unit, 7 is a reference level supply unit that supplies a reference level, A comparing section 8 which compares the output of the level detecting section 6 with the output of the reference level supplying section 7 and outputs an H level when the output of the level detecting section 6 is higher than the reference level; Reference numeral 11 denotes an output terminal that outputs the output of the comparison unit 8 as a determination result.

[0006] The operation of the conventional recording method discriminating apparatus configured as described above will be described below. Here, the first
Let us consider a case where a tape recorded by the recording method of (1) is reproduced.

First, the frequency-modulated luminance signal reproduced from the head enters the input terminal 1. The horizontal blanking period extracting section 2 extracts a horizontal blanking period portion of the frequency modulation luminance signal.
The first filter unit 3 is, for example, 3.8 in the PAL system.
In the vicinity of 1 MHz and the NTSC system, only components near 3.4 MHz pass. The output of the first filter unit 3 is supplied to a level detection unit 6. The level detector 6 detects the level of the frequency modulation luminance signal during the horizontal retrace period. The comparing section 8 compares the output of the level detecting section 6 with the reference level from the reference level supplying section 7, and if the output of the level detecting section 6 is larger than the reference level, determines that the first recording method is recorded. Then, an H-level signal is supplied to the output terminal 11. If the recording method other than the first recording method, that is, the second recording method is determined, an L-level signal is supplied to the output terminal 11.

[0008]

However, in the above-mentioned conventional configuration, the frequency modulation luminance signal of the first recording system recorded on the tape of the first recording system cassette is demagnetized by many uses. When the reproduced portion is reproduced, there is a problem that the output of the head is reduced and the recording method cannot be determined. This will be described with reference to FIG. FIG. 4 is a diagram showing a discrimination result in a conventional recording method discriminating apparatus. The output of the level detection unit 6 is large immediately after the recording in the case where the recording is performed in the first recording method cassette or the second recording method cassette in the first recording method. Therefore, the H level is supplied to the output terminal 11, and it is determined that the recording method is the first recording method. This result is correct.

On the other hand, when recording is performed by the second recording method, the frequency of the horizontal blanking period, for example, PAL
In the PAL system and the NTSC system, only components around 5.4 MHz are available.
In the SC system, the output of the level detector 6 is small because the component around 3.4 MHz is small. Therefore, the L level is supplied to the output terminal 11 immediately after recording or after demagnetization, and it is determined that the recording method is the second recording method. This result is also correct.

However, the output of the level detecting section 6 is small after demagnetization when recording is performed by the first recording method. Therefore, the L level is supplied to the output terminal 11,
It is determined to be the second recording method. This result is incorrect.
There are many tapes recorded by the first recording method in the world. As these are used many times, there are many tapes that are demagnetized in the world. Therefore, the frequency of occurrence of the error is high.

The present invention solves the above-mentioned conventional problems. When a frequency-modulated luminance signal of a first recording system recorded on a tape of a first recording system cassette is reproduced, demagnetization occurs. Even if the output of the head is reduced, it is possible to determine that the recording content is the first recording method,
Further, when reproducing the frequency-modulated luminance signal of the second recording method recorded on the tape of the cassette for the second recording method, even if the output of the head is reduced due to demagnetization, the recorded content is changed to the second content. It is an object of the present invention to provide a recording method discriminating apparatus capable of discriminating the recording method.

[0012]

SUMMARY OF THE INVENTION In order to achieve this object, a recording method discriminating apparatus according to the present invention reproduces a frequency-modulated luminance signal obtained by frequency-modulating a luminance signal by reproducing a recording medium. A magnetic recording / reproducing apparatus that determines a recording method of a luminance signal and demodulates the luminance signal into a luminance signal, a horizontal retrace period extracting unit that extracts only a horizontal retrace period from a frequency-modulated luminance signal reproduced from a head, A first filter unit for passing a frequency component near a carrier frequency in a horizontal retrace period portion of the first recording method in an output of the period retrieving unit; A second filter unit for passing a frequency component near a carrier frequency in a horizontal retrace period portion of the second recording system; and a second filter unit when the identification result of each recording system cassette indicates the first recording system. Selects the output of Iruta portion, the second
A first switching unit for selecting the output of the first filter unit, a level detecting unit for detecting the output level of the first switching unit, an output of the level detecting unit and a reference level. , An inverting unit for inverting the output of the comparing unit, and selecting the output of the inverting unit when the identification result of each cassette for the recording system indicates the first recording system, and selecting the second recording system. When shown, it has a configuration provided with a second switching unit for selecting the output of the comparison unit.

With this configuration, when the frequency modulation luminance signal of the first recording system recorded on the tape of the first recording system cassette is reproduced, even if the output of the head is reduced due to demagnetization, It is possible to determine that the recorded content is the first recording method, and when reproducing the frequency-modulated luminance signal of the second recording method recorded on the tape of the cassette for the second recording method, Even if the output of the head is reduced due to demagnetization, it is possible to determine that the recording content is the second recording method.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a method of recording a frequency-modulated luminance signal by reproducing a recording medium on which a frequency-modulated luminance signal obtained by frequency-modulating a luminance signal is recorded. A magnetic recording / reproducing apparatus that discriminates and demodulates to a luminance signal, a horizontal retrace period extracting unit that extracts only a horizontal retrace period from a frequency-modulated luminance signal reproduced from a head,
A first filter unit for passing a frequency component near a carrier frequency in a horizontal retrace period portion of the first recording method in an output of the horizontal retrace period extractor; and an output of the horizontal retrace period extractor. When the identification result of the cassette for each recording system indicates the first recording system, the second filter unit for passing the frequency components near the carrier frequency in the horizontal retrace period portion of the second recording system, and A first switch for selecting the output of the second filter and selecting the output of the first filter when indicating the second recording method; and a level for detecting the level of the output of the first switch. A detecting unit, a comparing unit that compares the output of the level detecting unit with the reference level, an inverting unit that inverts the output of the comparing unit, and an inverting unit when the identification result of each cassette for the recording system indicates the first recording system. Select the output of the second part And a second switching unit for selecting the output of the comparison unit when indicating the recording system, and when the identification result of each recording system cassette indicates the first recording system. Select the output of the filter unit of 2,
When the second recording mode is indicated, a first switching section for selecting the output of the first filter section is provided, so that the frequency of the first recording mode recorded on the tape of the first recording mode cassette is provided. When the modulated luminance signal is reproduced, even if the output of the head is reduced due to demagnetization, it is possible to determine that the recording content is the first recording method, and it is also possible to determine the recording content of the second recording method cassette. When reproducing the frequency-modulated luminance signal of the second recording method recorded on the tape, even if the output of the head is reduced due to demagnetization, it is determined that the recorded content is the second recording method. It has the effect of being able to.

Hereinafter, an embodiment of a recording method discriminating apparatus according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a recording system discriminating apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a frequency-modulated luminance signal reproduced from a video head. Is a horizontal retrace interval extracting unit for extracting a horizontal retrace interval portion from the frequency-modulated luminance signal from the input terminal 1, and 3 is the first of the outputs of the horizontal retrace interval extracting unit 2. The frequency of the horizontal retrace period portion of the recording method, for example, around 3.8 MHz in the PAL method, NT
In the SC system, the first band that passes only around 3.4 MHz is used.
The filter unit 4 passes only the frequency of the horizontal retrace period portion of the second recording method in the output of the horizontal retrace period extraction unit 2, for example, only about 5.4 MHz in both the PAL system and the NTSC system. The filter units 2 and 5 select the output of the second filter unit 4 when the identification result 12 of each cassette for each recording system indicates the first recording system, and select the first output when the identification result 12 indicates the second recording system. A first switching unit for selecting the output of the filter unit 3, a level detection unit 6 for detecting the output level of the first switching unit 5, a reference level supply unit 7 for supplying a reference level, and a level detection unit 6 Is compared with the output of the reference level supply unit 7. If the output of the level detection unit 6 is higher than the reference level, the comparator outputs the H level. If the output is lower than the reference level, the comparator outputs the L level. Inverting unit for inverting the output, 10 A second switching unit that selects the output of the reversing unit 9 when the identification result 12 of each recording system cassette indicates the first recording system, and selects the output of the comparison unit 8 when the identification result 12 indicates the second recording system , 11 is an output terminal for outputting the output of the second switching unit 10 as a discrimination result, and 12 is a discrimination result of each recording method cassette. For example, the first recording method cassette has no hole and the second recording method cassette has no hole. If the cassette has holes, it can be obtained by detecting the presence or absence of the holes.

The operation will be described below. First, consider the case where a tape recorded in the first recording system cassette by the first recording system is reproduced.

First, the frequency-modulated luminance signal reproduced from the head enters the input terminal 1. The horizontal blanking period extracting section 2 extracts a horizontal blanking period portion of the frequency modulation luminance signal.
The first filter unit 3 is, for example, 3.8 in the PAL system.
In the vicinity of 1 MHz and the NTSC system, only components near 3.4 MHz pass. In the second filter unit 4, only the components near 5.4 MHz pass in both the PAL system and the NTSC system. Since the identification result 12 of each recording method cassette indicates the first recording method, the first switching unit 5 sets
Terminal is selected. Therefore, the first switching unit 5 outputs a signal from the second filter unit 4. The output of the first switching unit 5 is supplied to the level detection unit 6. The level detector 6 detects the level of the frequency-modulated luminance signal during the horizontal retrace period using an amplitude detector or the like. The comparator 8 compares the output of the level detector 6 with the reference level from the reference level supplier 7, and outputs an L-level signal when the output of the level detector 6 is smaller than the reference level. In the inverting unit 9, the output of the comparing unit 8 is inverted, and an H level signal is output. Since the identification result 12 of each recording system cassette indicates the first recording system, the terminal b is selected in the second switching unit 10. Therefore, the second switching unit 10 outputs an H-level signal from the inverting unit 9. This output is supplied to the output terminal 11.

A description will be given of the result of the discrimination by the recording method cassette and the recording method with reference to FIG. FIG. 2 is a diagram illustrating a determination result in the recording method determination device according to the first embodiment of the present invention. As is apparent from the above, when recording is performed on the cassette for the first recording method by the first recording method, the output becomes H level immediately after the recording regardless of the demagnetization, and it is determined that the recording is performed by the first recording method. And get the correct result. The same applies to the case where recording is performed on the cassette for the second recording method by the second recording method.

On the other hand, when recording is performed by the second recording method on the first recording method cassette or when recording is performed on the second recording method cassette by the first recording method, an error occurs after demagnetization. These cases are considered to occur rarely.

As described above, according to the present embodiment, when the identification result of each cassette for each recording system indicates the first recording system, the output of the second filter unit is selected, and the second recording system is set. When shown, a first switching unit for selecting the output of the first filter unit was provided to reproduce the frequency modulation luminance signal of the first recording system recorded on the tape of the cassette for the first recording system. In this case, even if the output of the head is reduced due to the demagnetization, it is possible to determine that the recording content is the first recording method, and the recording content is recorded on the tape of the second recording method cassette. When reproducing the frequency-modulated luminance signal of the second recording method, it is possible to determine that the recorded content is the second recording method even if the output of the head is reduced due to demagnetization.

[0022]

As described above, according to the present invention, when the frequency modulation luminance signal of the first recording system recorded on the tape of the first recording system cassette is reproduced, the output of the head is reduced by demagnetization. Even if it has decreased, it is possible to determine that the recorded content is the first recording method, and it is also possible to determine the frequency modulation luminance signal of the second recording method recorded on the tape of the cassette for the second recording method. In the case where is reproduced, an excellent effect is obtained that even if the output of the head is reduced due to demagnetization, it is possible to determine that the recorded content is the second recording method.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a recording method discrimination device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a determination result in the recording method determination device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional recording method discriminating apparatus.

FIG. 4 is a diagram showing a determination result in a conventional recording method determination device.

[Explanation of symbols]

 Reference Signs List 2 horizontal blanking period extraction unit 3 first filter unit 4 second filter unit 5 first switching unit 6 level detection unit 7 reference level supply unit 8 comparison unit 9 inversion unit 10 second switching unit

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus for reproducing a recording medium on which a frequency-modulated luminance signal obtained by frequency-modulating a luminance signal is recorded, determining a recording method of the frequency-modulated luminance signal, and demodulating the frequency modulation luminance signal into a luminance signal. A horizontal retrace interval extracting unit for extracting only a horizontal retrace interval from the frequency-modulated luminance signal reproduced from the head, and a horizontal retrace interval portion of the first recording method in the output of the horizontal retrace interval extracting unit And a first filter unit for passing a frequency component near a carrier frequency in the horizontal retrace period extracting unit, and a frequency component near the carrier frequency in the horizontal retrace period part of the second recording method in the output of the horizontal retrace period extracting unit. When the identification result of the second filter unit for passing and the cassette for each recording system indicates the first recording system, the output of the second filter unit is selected, and when the second recording system is indicated, Previous A first switching unit for selecting an output of the first filter unit, a level detection unit for detecting a level of an output of the first switching unit, and a comparison for comparing an output of the level detection unit with a reference level. Unit, an inverting unit for inverting the output of the comparing unit, and selecting the output of the inverting unit when the identification result of each cassette for the recording system indicates the first recording system, and indicating the second recording system. Is a recording mode discriminating apparatus comprising a second switching section for selecting an output of the comparing section.