JPH05174310A - Recorded signal controller coping with magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent an inversion phenomenon even for the magnetic tape of a bad performance by measuring the performance of a magnetic tape once and controlling the emphasis quantity of a detail at the time of recording in accordance with its result. CONSTITUTION:At the time of test recording, a switch 5 is connected to a test terminal side(b), a signal from an FM modulator 3 is interrupted, a signal for testing is supplied to a rotary magnetic head 8 from an f1 and f2 test signal generator 4 via a recording icolizer circuit 6 and recorded on a tape 9. The recording is made on the tape 9 only for the period of time necessary for measuring a performance and then, a rewinding is made up to an index signal section and a reproduction is operated. The reproduced test signal is amplified at an amplifier 13, passed through a reproduction icolizer circuit 14, a signal having the frequency spectrum of f1 and f2 is taken out and the levels of each signal f1 and f2 are detected at detection circuits 17 and 18. The information of each detected level is passed through a tape simulator microcomputer 19, stored in a memory 20 and based on this data, a detail emphasis circuit 1 is controlled by the microcomputer 19 and the detail emphasis quantity of a recording video signal is set at an optimum value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording signal control device for controlling a recording signal corresponding to a recording medium in magnetic recording / reproduction, and more particularly to recording signal control for controlling characteristics of a video signal at the time of recording depending on the performance of a magnetic tape. Regarding the scheme.

[0002]

2. Description of the Related Art Conventionally, in a home VTR, a document "Introduction VTR (Kotaro Yokokawa, Tokyo Denki University Press)"
As described on pages 75 to 78, the recording current adjustment is provided for the purpose of setting the recording current flowing through the recording head winding to a value suitable for obtaining the maximum reproduction voltage. The recording current value for obtaining the maximum reproduction voltage, that is, the optimum recording current value is referred to below as ORC (Optimum Recording Curr
abbreviated as ent). However, the value of ORC is
It changes depending on the characteristic variations of the magnetic tape and the head in R. Further, even in the same VTR, the ORC shows different values if the magnetic tape as the recording medium is different.
Further, the ORC changes due to the temperature dependence of the magnetic tape and the head and the change over time. Further, the value of the ORC differs depending on the frequency of the recording signal depending on the performance of the magnetic tape. On the other hand, the setting of the recording current characteristic that has been conventionally performed is made possible by considering the above various factors of variation as much as possible,
A method of obtaining an average ORC value and uniformly applying the average ORC value to a set of mass-produced VTRs has been used.

In order to solve the problems of the above-mentioned conventional example, there is a recording current control device shown in Japanese Patent Laid-Open No. 2-187902 as shown in FIG. In the figure, 23 is a recording head for recording signals for ORC detection, 24 is a magnetic tape,
25 and 30 are rotary transformers, 26 is a recording amplifier, 27 is a gain switching control unit for controlling the gain switching of the recording amplifier 26, and 28
Is a comparison / judgment unit that compares a plurality of input DC potentials with each other and gives an instruction regarding gain setting to the gain switching control unit based on the result. 29 is a magnetic tape by the magnetic head 23.
A reproducing head for reproducing the signal recorded on 24, 31 is a reproducing preamplifier, and 32 is a detection circuit for smoothing the output of the reproducing preamplifier 31 and converting it into a DC potential.

FIG. 2A is a characteristic diagram showing an example of reproducing head output f characteristics of A tape and B tape having different characteristics.

FIG. 2B is a characteristic diagram showing an example of reproduced video f characteristics of the A tape and the B tape when a video signal is recorded and reproduced on the tape having the reproduction head output f characteristic.

Next, the operation will be described. At the time of recording, it is applied to the magnetic head 23 through the signal rotation transformer 25 amplified by the recording amplifier 26, and recorded on the magnetic tape 24. At this time, recording is performed with a plurality of different recording current values according to an instruction from the gain switching control unit 27. At the time of reproduction, the signal written on the magnetic tape 24 is detected by the magnetic head 29 and input to the preamplifier 31 via the rotary transformer 30,
The amplified output signal is input to the detection circuit 32. The signal smoothed by the detection circuit 32 is input to the comparison / determination unit 28.
The comparison and judgment section 28 compares the input signal potentials of a plurality of types to find the ORC.

[0007]

The conventional VTR is designed in accordance with the lowest rank magnetic tape so as to prevent reversal phenomenon (vibration) and secure S / N for any magnetic tape. There is. Therefore, when a high-performance magnetic tape is used, the S / N can be secured even if recording with more detail is originally made, but the image has a good S / N.

Since the recording current control device shown in FIG. 6 is constructed as described above, the ORC of various magnetic tapes is used.
However, since the ORC is measured only at a single frequency, the frequency characteristic of the magnetic tape has not been corrected, and FIG.
The sideband recording / reproducing level of the FM-modulated wave of the video signal recorded / reproduced as shown in FIG. 6 causes a change in the performance of various magnetic tapes, and the reproduced video signal has the same characteristics as the reproduced video f characteristic shown in FIG. 2B. However, there are problems such as variations in the image quality of.

The present invention is applicable to a magnetic recording medium in which a test recording is carried out with respect to frequency characteristics for re-recording and reproducing signals on various magnetic tapes, and the image quality of recorded / reproduced video signals does not vary due to variations in performance of the magnetic tapes. The purpose is to obtain a recording signal control device.

[0010]

In order to achieve the above object, a recording signal controller for a magnetic recording medium according to a first aspect of the present invention uses a magnetic tape to record a plurality of test signals having different frequencies. The recorded portion of the test signal is recorded by a predetermined ORC, the levels of a plurality of test signals are detected at this time, and the detected levels are stored. At the same time, the frequency of the magnetic tape on which the test recording is performed is recorded. It is characterized in that the characteristics are processed by the microcomputer, and the microcomputer controls the waveform response characteristics of the recording video signal according to the processing result so that the image quality of the recording / reproducing video signal does not vary due to the variation in the performance of the magnetic tape.

A recording signal control device corresponding to a magnetic recording medium according to the second invention uses a subcarrier signal of a chroma signal as a first test signal among a plurality of test signals having different frequencies. It is characterized in that a signal obtained by doubling the first test signal is used as the second test signal, and the test signals having the first and second frequencies are added to create a plurality of test signals having different frequencies. ..

[0012]

Therefore, according to the recording signal control device corresponding to the magnetic recording medium of the present invention, the frequency characteristics of recording and reproducing on various magnetic tapes can be tested and stored, so that the microcomputer can record the recording video signal. The waveform response characteristic can be controlled.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a recording signal control device corresponding to a magnetic recording medium of the present invention, 1 is a detail emphasizing circuit of an incoming recording video signal, 2 is pre-emphasis of recording, 3 is an FM modulator, Reference numeral 4 is an f1, f2 test signal generator having two different frequency f1 and f2 spectra, 5 is a switch circuit for switching between test recording and normal recording, 6 is a recording equalizer circuit, and 7 is for supplying a recording current. Recording amplifier, 8 is a rotary magnetic head for recording / reproducing, 9 is a magnetic tape of a recording medium, 10 is a control head for recording / reproducing index signals and control signals on a control track of the magnetic tape 9, and 11 is a control head. CTL sending and receiving signals to 10
A pulse recording / reproducing circuit 12 is a system control microcomputer for controlling the operation of the VTR.

Reference numeral 13 is a reproduction amplifier for amplifying the reproduction signal read from the magnetic head 8, 14 is a reproduction equalizer circuit, and 15 is a reproduction equalizer circuit.
Is an FM demodulator, 16 is de-emphasis for outputting a reproduced video signal, 17 is an f1 level detection circuit for a test signal of frequency f1 reproduced from the magnetic tape 9, and 18 is also f
2 level detection circuit, 20 is a memory for storing the level detection results of the f1 level detection circuit 17 and the f2 level detection circuit 18,
A tape simulator microcomputer 19 stores the level detection results of the f1 level detection circuit 17 and the f2 level detection circuit 18 as data in the memory 20 and controls the detail emphasizing circuit 1 according to the level detection results.

FIG. 3 is a block diagram showing a means for generating f1 and f2 test signals in the recording signal control device corresponding to the magnetic recording medium according to the second invention. In FIG. 3, f1 is existing in the VTR. A signal, for example, a signal having a subcarrier frequency of a chroma signal, 21 is a doubling circuit that doubles f1 to generate a test signal of f2, and 22 is the above-mentioned f
It is an adder circuit for creating f1 and f2 test signals from the signals of 1 and f2.

FIG. 4A is a characteristic diagram showing an example of the level of the reproducing head output of the spectrum of the test signals f1 and f2 when the f1 and f2 test signals are recorded and reproduced on the A tape.

FIG. 4B is a characteristic diagram showing an example of the level of the reproducing head output of the spectra of the test signals f1 and f2 when the f1 and f2 test signals are recorded and reproduced on the B tape.

FIG. 5 is a flow chart showing the operation of the present invention.

Next, the operation will be described. A tuning button is provided on the front panel of the VTR main body, and the tape simulator is operated in order to detect the optimum recording state of the above-mentioned cassette tape by operating this tuning button before the user records, that is, after mounting the cassette tape on the VTR. The microcomputer 19 operates according to the program in the memory 20 according to the flowchart shown in FIG.

In the above operation, during test recording, the switch circuit 5 is connected to the terminal (b) side (test terminal side) to cut off the signal from the FM modulator 3, and instead, the test signal is f1. , F2 is supplied from the test signal generator 4 to the recording equalizer circuit 6, is supplied to the rotary magnetic head 8 via the recording amplifier 7, and is recorded on the magnetic tape 9.

Here, according to the operation timing of the tape simulator microcomputer 19, the CTL pulse recording / reproducing circuit 11 controlled by the system control microcomputer 12 records an index signal on the magnetic tape 9 at a predetermined timing by the control head 10.

On the other hand, the magnetic tape recorded for the time required for measuring the tape performance is rewound to the index signal section and reproduced.

Here, the reproduced test signal is amplified by the reproduction amplifier 13, passes through the reproduction equalizer circuit 14, and then, as shown in FIG.
A signal having the frequency spectrum of f1 and f2 shown in (a) or FIG. 4 (b) is taken out, the level of the test signal f1 is detected by the f1 level detection circuit 17, and at the same time, the level of the test signal f2 is the f2 level. Information of each detection level detected by the detection circuit 18 is stored in the memory 20 through the tape simulator microcomputer 19, and the tape simulator microcomputer 19 controls the detail emphasizing circuit 1 by the data stored in the memory 20 and records the information. Set the amount of detail enhancement of the video signal to the optimum value.

When the above setting is completed, the switch circuit 5 is returned to the normal recording side (a), rewound to the index signal section, and the test recording is completed.

At the time of recording after the above setting, the detail of the incoming recording video signal is emphasized by the detail emphasizing circuit 1 in which the emphasizing amount is set to the optimum value, and the recording pre-emphasis 2 is applied. F by FM modulator 3
The M modulated wave is supplied to the recording equalizer circuit 6, supplied to the rotary magnetic head 8 via the recording amplifier 7, and recorded on the magnetic tape 9.

The reproduced signal extracted from the magnetic tape 9 by the rotary magnetic head 8 during reproduction is reproduced by the reproducing amplifier 13.
The signal is amplified by the FM demodulator through the reproduction equalizer circuit 14.
It is demodulated in 15 and is extracted as a reproduced video signal through reproduction de-emphasis 16.

Further, the circuit for generating the f1 and f2 test signals in the second invention will be described with reference to the operation of the block diagram showing the embodiment of FIG.

In the figure, f1 is an existing signal in the VTR, for example, a signal having a subcarrier frequency of a chroma signal, the doubler circuit 21 doubles f1 to generate a test signal f2, and the adder circuit 22 From the above f1 and f2 signals, f
1. Create f2 test signal.

Further, in the above embodiment, the signal of the subcarrier frequency of the chroma signal is used for f1, but the clock of the microcomputer (4 MHz or the like) may be used.

[0030]

As described above, in the recording signal control device corresponding to the magnetic recording medium according to the present invention, the microcomputer performs the recording video so that the image quality of the recording / reproducing video signal does not vary due to the difference in the performance of the magnetic tape. Since it is characterized by controlling the waveform response characteristics of the signal, it is possible to prevent the reversal phenomenon (blurring) even on magnetic tape with poor performance.
It is said that S / N can be secured, and high-performance magnetic tape has a margin against the reversal phenomenon (blurring) even if more detail is recorded, and an image with good S / N can be obtained. effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a recording signal control device corresponding to a magnetic recording medium that is an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a difference in reproducing head output f characteristic on a magnetic tape and a characteristic diagram showing a difference in reproducing video f characteristic.

FIG. 3 is a block diagram of an apparatus for creating a plurality of test signals, which is an embodiment of the second invention.

FIG. 4 is a diagram showing the levels of a reproducing head output of a plurality of test signal spectra on a magnetic tape.

FIG. 5 is a flowchart showing an operation in the recording signal control device corresponding to the magnetic recording medium that is an embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional recording current control device.

[Explanation of symbols]

 1 Detail enhancement circuit 12 f1, f2 test signal generator 5 Switch circuit 8 Rotating magnetic head 9 Magnetic tape 10 Control head 11 CTL pulse recording / reproducing circuit 12 System control microcomputer 17 f1 level detection circuit 18 f2 level detection circuit 19 Tape simulator microcomputer 20 Memory 21 2 multiplication circuit 22 Addition circuit

Claims (2)

[Claims] 1. A magnetic recording / reproducing apparatus for recording a video signal on a magnetic recording medium and reproducing the video signal, and means for generating a plurality of test signals having different frequencies, and a magnetic tape which is the recording medium for the plurality of test signals. Video recording means for recording on a video track of, a means for automatically rewinding and reproducing to a recording portion after recording for a fixed time, and a test signal of each frequency by reproducing the plurality of test signals from the magnetic tape. Detecting means for detecting the level of the test signal, memory means for storing the level of the detected test signal, judging means for judging the characteristics of the magnetic tape based on the data in the memory, and recording means based on the characteristics of the magnetic tape. It is equipped with a means to control the amount of detail enhancement of the video signal of, and the performance of the magnetic tape is measured once. Recording signal control apparatus corresponding to the magnetic recording medium characterized by controlling the amount of enhancement Iteru. 2. The recording signal control device corresponding to the magnetic recording medium according to claim 1, wherein the sub-carrier frequency of the chroma signal is added to the test signal of the first frequency as means for generating a plurality of test signals having different frequencies. Means for using the above signal, means for doubling the signal of the subcarrier frequency of the chroma signal as the test signal of the second frequency, and means for adding the test signals of the first and second frequencies. A recording signal control device compatible with a magnetic recording medium.