JP3443968B2 - Recording / playback method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a tape for optimizing a recording current and a reproduction signal waveform in a video tape recorder,
The present invention relates to a recording / reproducing method for accurately measuring and setting the optimum value of the recording / reproducing conditions including the head in each head in a short time.

[0002]

2. Description of the Related Art In recent years, the tapes and heads of video tape recorders have been actively improved. However, on the other hand,
Optimal conditions are not the same for various combinations of tapes and heads, and even initial settings are not necessarily optimal values.

Therefore, there is a movement to solve such a problem. Conventionally, the configuration as shown in FIG. 5 has been general.

The following structure will be described with reference to FIG. In FIG. 5, reference numeral 1 is a video signal recording / reproducing unit including a cylinder, a rotary magnetic head, a traveling system, and an electric circuit for controlling them. Reference numeral 2 mainly comprises a microcomputer for controlling the video signal recording / reproducing section 1 in a recording / reproducing measuring mode, and also for erasing current generating circuit 7, switching circuits 8, 9, recording current setting circuit 3, reproducing output measuring circuit 5 and reproducing. A control signal generator that supplies a control signal to the signal processing circuit 4 to control each circuit and set an operating point. Reference numeral 3 is a recording current setting circuit controlled by the control signal generating unit 2, 4 is a reproduction signal processing circuit for processing the reproduction signal reproduced by the video signal recording / reproducing unit 1 under the control of the control signal generating unit 2, and 5 is a reproduction output. A measuring circuit, 6 is an input terminal, 7 is an erase current generating circuit, 8 is a switching circuit for selecting and outputting either the erase current generating circuit 7 or the recording current setting circuit 3 under the control of the control signal generating section 2, 9
Is a switching circuit for switching the signal from the video signal recording / reproducing unit 1 to the reproduction signal processing circuit 4 or the reproduction output measuring circuit 5.

The outline of each of the above modes will be described. First, when the optimum recording current is set by the combination of the magnetic tape and the video head, the control signal is sent to the running system of the video signal recording / reproducing unit 1 and an electric circuit for controlling them. A control signal is applied by the generator 2, and after the tape is loaded, the control signal generator 2 holds the tape in a stationary state, and the control signal generator 2 generates a sine wave signal having a frequency for setting an optimum recording current, and switches the tape. Recording current setting circuit 3 via circuit 8
The recording current having the above frequency is supplied to the recording medium, and the recording current is changed stepwise on one track while the tape is stationary.

At the time of recording, first, the erasing current generated by the erasing current generating circuit 7 is switched by the switching circuit 8 to be supplied to the rotary magnetic head of the video signal recording / reproducing section 1 so as to move up one track. The track is erased by recording the erase current, and then the recording current changed stepwise by the recording current setting circuit 3 is recorded.

Next, at the time of reproduction, the same rotary magnetic head used at the time of recording by the video signal recording / reproducing unit 1 reproduces the above stepwise recorded signal on one track, and the reproduction output thereof is the switching circuit 9. It is then given to the reproduction output measuring circuit 5. In the case of the optimum recording current setting, the maximum value detection circuit is used. At this time, the maximum value information of the reproduction output measuring circuit 5 is output to the control signal generating section 2 as a set value of the optimum recording current of the head and stored in the microcomputer therein. By supplying the information to the recording current setting circuit 3 and the reproduction signal processing circuit 4, the optimum condition of the recording / reproducing system is set.

After that, when the normal recording is performed, the recording is performed at the optimum recording current value which is the set value at the time of measurement. Further, in the case of normal reproduction, the switching circuit 9 is connected to the reproduction signal processing circuit 4 and the video output 10 is executed under the optimum condition of the reproduction system.
Is output from.

[0009]

However, in the above-mentioned conventional configuration, an erasing circuit is required to eliminate the influence of overwriting when measuring the respective heads, and three erasing operations, recording and reproducing, are performed after the erasing operation. Action is required. Therefore, there are problems that the number of circuits is increased, the cost is increased, and the control is complicated.

Even during normal reproduction, the optimum value of the reproduction frequency characteristic setting is not constant due to various combinations of the head and tape states. Therefore, if the initial setting value deviates from the optimum setting value, the image quality deteriorates. There was a problem that it may happen.

The present invention solves the above-mentioned problems of the prior art, and the measurement and setting of optimum conditions of a recording / reproducing system including a tape and a head in a video tape recorder can be accurately and easily performed at low cost in a short time. It is an object of the present invention to provide a method and a recording / reproducing method that always outputs the optimum image quality by always measuring the reproducing condition during normal reproduction and performing the set value by real-time control.

[0012]

In order to solve the above-mentioned problems, the recording / reproducing method of the present invention comprises a tape holding means for holding the tape in a stationary state after loading the tape and an inverse of the tape holding means.
They have a relationship of azimuth angles and have a track width smaller than the track widths of the first and second video heads for recording and reproducing the video signal as standard, and 1 / n of the standard mode. First bidet to record and play at the speed of
Third video on azimuth angle opposite Ohead
Head and the second video head and the opposite azimuth angle Seki
And a fourth video heads in engagement, still like the tape
In a state where it can be changed to a tape on one track in steps
To generate a recording current, and
The same video as the video head used for recording.
The signal on the track is reproduced by the Deohead, and the reproduction is performed.
The recording current value that maximizes the output is optimized for that video head.
Set the step to set the current value as the first video head.
Second video head, fourth video head, third video head
Execute in order of video heads, and for each video head
It is characterized by setting an optimum current value .

[0013]

With this structure, the optimum condition of the recording / reproducing system including the head tape can be measured for each head in one track obtained when the tape is stationary. Also,
By utilizing the azimuth angle of each head, overwriting recording does not affect each other. As a result, since circuits other than the recording and reproducing operations, which are the basic performance of video, are not required, the measurement and setting of each head can be performed easily, at low cost, and in a short time with high accuracy.

Regarding the recording / reproducing position, the influence of the control signal, the unstable portion of the power source at the time of mode switching, and the influence of the drop in the reproduction output of the worn head, and the upper and lower ends of the tape which is less susceptible to tape damage Further accuracy can be achieved by avoiding the use and using the central part of the tape.

Furthermore, during normal reproduction, the reproduction output is constantly measured to find the optimum adjustment value for the signal waveform according to the time, and this value is set in the reproduction signal processing circuit, so that the optimum video is always produced. Can be output.

[0016]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, the same components as those of the prior art are designated by the same reference numerals and the description thereof will be omitted. The difference from the prior art is that the switching circuit and the erasing current generating circuit are omitted and the measurement recording signal generating circuit 11 is provided.

A description will be given of a case where the optimum recording current is measured using these configurations and the recording current setting circuit 3 is set.

By supplying a control signal from the control signal generator 2 to the running system of the video signal recording / reproducing unit 1 and an electric circuit for controlling them, the tape is put in a stationary state, so-called pause / still state after the tape loading. The recording current setting circuit 3 generates a sine wave signal having a frequency for setting the optimum recording current by the recording signal generating circuit 11 for measurement.
To the recording current for measurement. The signals of A, B, and C in FIG. 3D are shown on one track while the tape is stationary in FIG.
By inputting each switch in (e) to a circuit equipped with a switch that turns on when it is'H ', the resistance division ratio between the input and the output of the recording current is changed, so that the step shape as shown in FIG. To change the recording current IR.

At the time of recording, the recording current changed stepwise on the tape on one track by the rotary magnetic head of the video recording / reproducing system 1 is controlled by the control signal generator 2 as shown in FIG. An operation timing signal for determining such a recording position is generated, and recording is performed at the central portion of the tape, which is the black-painted portion in FIG. 3 (h).

FIG. 3 (a) is an enlarged view of FIG. 2 (a). Next, at the time of reproduction, the same rotary magnetic head used at the time of recording by the video signal recording / reproducing unit 1 reproduces the signal recorded in steps as shown in FIG. 3C, and its reproduction output is normally as shown in FIG. As shown in FIG. 3C, the reproduction output measuring circuit 5 detects the reproduction output V _ENV of the portion A in FIG. 3C as the maximum value. Then, the maximum value information of the reproduction output measuring circuit 5 is given to the microcomputer of the control signal generating section 2 and is the recording current value that can output the maximum output of A of FIG. ) B value is stored. The information is used as the setting value of the optimum recording current, and FIG.
The optimum conditions of the recording system are set by determining the outputs of A, B, and C in (d) and supplying them to the recording current setting circuit 3.

At this time, the measurement sequence is determined by the control signal generator 2 before and after each head measurement so that the azimuth angle relationship is reversed.

After that, when the normal recording is performed, the recording is performed at the optimum recording current value which is the set value of the recording current setting circuit 3.

Further, at this time, the reproduction output measuring circuit 5 is shown in FIG.
And V _ENV playback output that occurs in the head clogging, such as is hardly output of (f), V Fig. 3 (g) a sudden drop in reproduction output that occurs in such tape wound has occurred _ENV
Are also detected at the same time, and if such a case occurs,
The control signal generator 2 sets, in the recording current setting circuit 3, the average values of the optimum recording currents that can be estimated from the combinations of the heads and various tapes determined in advance at the terminals A, B and C of FIG.

In the case of normal reproduction, the level of the reproduction output from the head is constantly measured by the reproduction output measuring circuit 5, and the optimum set value information suitable for the level is reproduced signal processing circuit 4.
The reproduced signal processing circuit 4 adjusts the RF equalizer, the amount of noise cancellation, and the frequency characteristics of the baseband according to the information to adjust the signal waveform, and as a result, it is always output at the video output terminal 10 under the optimum condition.

The detailed measuring operation will be described with reference to the time chart of FIG. This will be described by taking as an example the case where the optimum recording current of a 4-head mounted video tape recorder is obtained.

First, the switching of the heads of the video recording / reproducing unit 1 is performed by the control signal generating unit 2 as shown in FIGS.
The four heads are switched by the combination of H and L as shown in FIG. Where HR (s), HR and HL (s),
HL is the same azimuth angle. The structure is shown in FIG.

In synchronism with this head switching, the video signal recording / reproducing unit 1 switches to the recording system when it is'H 'and to the reproducing system when it is'L', as shown in FIG. 2 (c). Figure 2 (d)
Is an operation timing signal of the same recording / reproducing position as in FIG.

The details will be described. For example, HR
If it is started when the head in (s) is in contact with the tape in the stationary state in the measurement mode, the control signal generator 2
2A, 2B, 2C, and 2D, the video signal recording / reproducing unit 1 switches to the recording system and the measurement recording signal generating circuit 11 and the recording current setting circuit are supplied. The recording current changed to the step shape of FIG. 3 (c) by giving the control signal to 3 is sent to the video recording / reproducing system 1, and the head of HR (s) makes one step on the tape. The recording current is supplied to record.

Then, when the head is rotated once again and switched to the HR (s) head again, the reproducing operation is performed. At that time, the control signal generator 2 is connected to each circuit as shown in FIGS.
By giving the signals of (c) and (d), the video signal recording / reproducing unit 1 is switched to the reproducing system, and the reproduction output of the head of HR (s) is measured by the reproduction output measuring circuit 5 at the maximum value of the output. Then, the recording current for outputting the maximum value at that time is set as the optimum recording current, and the value is stored in the microcomputer of the control signal generator 2 so that the recording current setting circuit 3 can supply the optimum recording current value to the head. To do. This completes the measurement and setting of the optimum recording current for one head HR (s).

Next, after a half rotation, the same recording / reproducing operation is performed by the head of HL (s) having an azimuth angle opposite to HR (s), and thereafter the azimuth angle opposite to HR and HL is obtained. In this way, the control signal generator 2 controls the measurement in the order shown in FIG.

At this point, the control signal generator 2 stores the value of the optimum recording current of each of the four heads, and the subsequent recording is performed with this value until the tape is taken out.

By performing the recording / reproducing measurement as described above, the optimum recording current value of each head can be efficiently measured. That is, in reality, the recording of each head is overwrite recording, but by recording with the heads of opposite azimuth, the influence of the previous track is eliminated, and the optimum recording current value can be measured efficiently.

With this configuration, the time required for measuring and setting the optimum conditions of the recording / reproducing system including the head tape is 0.25 seconds (7 rotations) in the case of 4 heads, as can be seen from FIG. ) Can be completed in a short time,
By changing the frequency of the sine wave signal recorded in the measurement recording signal generating circuit 11, it is possible to successively measure and set several characteristics such as the recording current F characteristic, the reproduction F characteristic and the signal waveform. In the case of 2 heads, it takes 0.1 seconds (3 rotations).

Next, control during normal reproduction will be described. During reproduction, the reproduction output from the head is detected by DC in the detection circuit of the reproduction output measuring circuit 5 to determine the S / N value of the reproduction output according to the measured value of the voltage (Table 1).
And sends a control signal to the reproduction signal processing circuit 4 corresponding to each estimated value, and each adjustment circuit as shown in (Table 2) controls the reproduction frequency characteristic for a signal with a good S / N ratio. By adjusting to the direction of increasing the signal frequency and, on the contrary, to the signal of poor S / N, decreasing the frequency characteristic of reproduction, the signal waveform is optimized in the reproduction output state at that time as shown in (Table 2). To do. As a result, the optimum image quality is output from the video output 10.

[0036]

[Table 1]

[0037]

[Table 2]

The hysteresis characteristic for preventing chattering, which is a feature of this control method, will be described with reference to FIG. The hysteresis characteristics of the measuring method during reproduction are roughly divided into two characteristics. One is based on the reproduction output value, and the other is based on time.

FIG. 4A is a graph showing the operation depending on the reproduction output value. As shown in this graph, level 1.2
The rising values of are points b and d, respectively. However, at the trailing edge, points a and c respectively become b,
Since the value is lower than the point d, it is a against the fluctuation of the playback output value due to the vibration or vibration of the running system, the tape tension, etc.
-B, cd difference in level detection value between levels 1 and 2
It prevents the output value from chattering.

As another prevention method by time, FIG. 4B shows how the actual level display changes with respect to the fluctuation of the reproduction output value. After the reproduction output value reaches the level 1 at the point A, if that state continues for a certain period of time, the level 1 is actually output at the point B. The operation of level 2 is similar. Therefore, the chattering does not occur in the output values of the levels 1 and 2 with respect to short-time fluctuations in the output level caused by scratches on the tape at points C to D and points E to F and noise. Therefore, it is possible to realize stable operation without chattering with respect to any variation in the reproduction output value.

As described above, according to this embodiment, there is no increase in peripheral circuits due to the erasing current generating circuit 7 and the switching circuits 8 and 9 which are the problems of the prior art, the control is simple, and it can be realized at low cost. Further, by setting the recording / reproducing position of the tape by the control signal generating means 2, it is possible to perform accurate measurement for each head in a shorter time, so that an accurate set value can be set.

In addition, even during normal reproduction, it is possible to perform stable settings in which chattering does not occur in real time by the two types of hysteresis functions, so that the signal waveform can be stably adjusted to the optimum signal waveform at each time. Thus, the optimum image can be output from the image output 10.

[0043]

As described above, the present invention eliminates the erasing function of the erasing current generator and the switching circuit as in the conventional configuration and utilizes the azimuth angle of the heads, thereby making it possible to perform overwriting recording by a large number of heads. The influence of the control signal, the unstable portion of the power supply for mode switching, and the drop of the reproduction output of the worn head, and the influence of the tape damage are received at the recording / reproducing position by the control signal generating means 2. Avoid using the top and bottom edges of cheap tapes and record / play back at the center of the tape.

Therefore, before the normal recording, a measuring / setting period in which the tape is in a stationary state is provided, and the optimum recording / reproducing conditions including the tape and the head are accurately measured for each head in a short time. The optimum conditions for each head can be set.

In addition, even during normal reproduction, it is possible to correspond to all soft tapes as well as self-recording, and the measurement method is a stable operation in which chattering does not occur due to the fluctuation of the reproduction output of the head by the hysteresis function, and the set value is set. Therefore, a stable and optimum signal waveform can always be output as an optimum image.

This makes it possible to realize an excellent video tape recorder capable of recording and reproducing by each head under the condition that the recording / reproducing characteristics including the tape and head of the video tape recorder are always optimum. .

[Brief description of drawings]

FIG. 1 is a block diagram of a recording / reproducing method according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is an operation explanatory diagram at the time of recording and reproducing in the embodiment.

FIG. 4 is a hysteresis characteristic diagram of the reproduction output measuring circuit in the same embodiment.

FIG. 5 is a block diagram of a conventional recording / reproducing method.

[Explanation of symbols] 1 Video recording / playback section 2 Control signal generator 3 Recording current setting circuit 4 Playback signal processing circuit 5 Playback output measurement circuit

Claims (2)

(57) [Claims] 1. A tape holding means for holding the tape in a stationary state after loading the tape, first and second video heads having a reverse azimuth angle relationship and for standard recording and reproducing a video signal, and the first video head. And an azimuth angle opposite to that of the first video head having a track width smaller than that of the second video head and recording / reproducing at a speed of 1 / n of the standard mode.
The third video head and the second bidet in a degree relationship.
It is equipped with a fourth video head having an azimuth angle opposite to that of the audio head, and the tape is set to a stationary state and the tape is moved to the tape one track above.
The recording current changed on the recording medium is generated.
It was recorded by a video head that was slightly off and used for the recording.
The track is recorded by the same video head as the video head.
Recording current that reproduces the above signal and maximizes the reproduction output
Value to set the optimum current value for that video head.
Up the first video head, the second video head, the front
The fourth video head and the third video head are executed in this order, and the video
A recording / reproducing method characterized by setting the optimum current value of the head . 2. The tape remains stationary after loading the tape.
Standards and tape holding means for holding, is in the opposite azimuth angles each other, a video signal to
Smaller than the track widths of the first and second video heads for recording / reproducing and the first and second video heads.
It has a short track width and is 1 / n the speed of standard mode.
Azimuth angle opposite to that of the first video head for recording and reproduction
The third video head and the second bidet in a degree relationship.
Fourth video on azimuth angle opposite Ohead
A head and a recording signal for measurement that generates a sine wave signal of a predetermined frequency
The output signal of the raw circuit and the recording signal generating circuit for measurement is stepped up.
The recording current setting circuit that changes the recording current and the tape in the stationary state, and the output signal of the recording current setting circuit
Any said first to fourth a control signal recorded and Play No.
Control signal generating circuit for sending to the video head, and detecting the maximum value from the reproduced output,
A reproduction output measuring circuit for detecting a recording current value for controlling the first video head, the control signal generating circuit,
The second video head, the fourth video head, and the third video head are paired.
Recording characterized by transmitting control signals in this order
Playback device.