JPS62128286A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To realize quick reproduction having no noise with a picture high in quality and without bending by adding a recording means of picture information corresponding to the signal lacking part of a reproducing picture and the phase synchronizing means of a horizontal synchronizing signal. CONSTITUTION:The signal of the changeover signal generator 15 or the voltage comparator 6 of pseudo vertical synchronizing signal generator 8 indicates the reproduction of a high noise part and a low noiseless part. A horizontal synchronizing signal detector 70 counts the clock from a clock generator 9 and continues to count synchronously with the output from a horizontal synchronizing signal detector 7, namely the horizontal synchronizing signal in a reproducing video signal. Then, the noise part is reproduced, a signal 76 is inverted to a high state, a logical circuit 71 operates to generate a preset pulse and repeats the counting operation is a period equal to a horizontal synchronizing period. According to such operation, even when the noise part is reproduced, the horizontal synchronizing signal can be obtained continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus, and more particularly to a magnetic recording and reproducing apparatus suitable for quickly reproducing a magnetic tape recorded in a helical scan type apparatus.

[Conventional technology]

Conventional devices, as described in Japanese Patent Application Laid-Open No. 56-166678, merely fix the noise bar generated on the screen at a fixed position. This means that during quick playback, the running speed of the magnetic tape is n times that of recording (n is an integer of 2 or more), and the phase detection output and playback control a-non-signal according to the rotational phase of the rotary head are multiplied by 1/n. The rotation of the capstan motor is controlled so that the phase matches the output of the capstan motor. However, when one rotary head scans once, the signal dropout that occurs when a plurality of recording tracks are successively traversed and reproduced remains only at a fixed position on the television screen.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, no consideration was given to measures to remove or reduce the occurrence of noise on the television screen, resulting in unreliable reproduced images.

An object of the present invention is to provide a magnetic recording and reproducing apparatus that removes noise on the 5-screen and produces a good screen.

[Means for solving problems]

The above object is achieved by adding means for recording image information corresponding to signal missing portions of a reproduced image and means for synchronizing the phase of a horizontal synchronization signal.

[Effect]

The image memory according to the present invention stores the previously reproduced image signal and operates to output the signal when the signal is missing. Furthermore, the horizontal synchronization signal synchronization means generates a pseudo horizontal synchronization signal when the signal is missing, and controls the head rotation speed when the signal is restored to a state where the signal is reproduced again. A control operation is performed so that the memory and the head rotation (playback horizontal synchronization signal that half-reflects the head rotation) are synchronized. These enable good quick playback without noise.

〔Example〕

An embodiment of the present invention will be explained below using a block diagram shown in FIG. In FIG. 1, 1 is a magnetic tape, 2 and 3 are rotary heads, 4 is an amplifier, 5 is a video signal demodulator, 6 is a drum motor, 7 is a horizontal sync signal detector, and 8 is a pseudo horizontal sync signal generator. , 9 is a clock signal generator, 10 is an address generator) (g, 11 is an image memory, 12 is a pseudo vertical synchronization signal generator, 13 is a phase comparator, 14 is a drum rotation frequency signal generator (hereinafter referred to as a DFG generator) ), 15 is a switching signal generator, 16.17 is an interlocking changeover switch, 18 is a video signal processing circuit, 19 is a television screen, 20 is a motor driver, 2L is an analog-digital converter &!
2 is a digital-to-analog converter. The operation of this embodiment will be explained below. First, the rotary head 2.degree.3 reproduces an image signal recorded on the magnetic tape 1. This reproduced signal is amplified by an amplifier 4 and demodulated into a video signal by a video signal demodulator 5.

The horizontal synchronization signal detector 7 extracts the horizontal synchronization signal from this reproduced video signal. This is commonly used in the past. It may be composed of a voltage comparator or the like. Furthermore, the clock signal generator 8 operates to generate a clock signal that is phase-synchronized with the color subcarrier signal, and is a general type composed of a phase comparator, a voltage controlled oscillator, a smoothing circuit, and the like. This general configuration is shown in FIG. In FIG. 2, 40 is a phase comparator, 41 is a smoother, 42 is a voltage controlled oscillator, 43 is a counter, 44 is an input terminal, 4
5 is an output terminal. Clock signal oscillator 8 in the present invention
When using the configuration shown in FIG. 2, a color subcarrier signal is applied to the input terminal 44, and the count of the counter 43 is set to an appropriate frequency division ratio. The output signal 45 generated here is used as a sampling clock for the video signal in the overall configuration of FIG. Therefore, the counting frequency division ratio of the counter 43 is set to about 3.4. As a result, the output Glock becomes about 3.43 of the one-color subcarrier signal.

Next, the specific configuration and main operations of the address generator 10 will be described below using the block diagram shown in FIG.

In the block diagram of FIG. 3, 50.51 is a counter for address generation, 52 to 54 are signal input terminals, and 5
2.54 is the preset (or reset) input, 5 is the preset (or reset) input.
3.55 each accepts a clock input. These two counters 50 and 51 give addresses of two dimensions (x, y>) of information to be stored in the image memory 11. Here, (xyy) are respectively equivalent to the positions of pixels on the television screen. The counter 51 counts the clock signal generated by the clock generator 9 and indicates the horizontal position of the screen, and the counter 51 counts the output signal of either the horizontal synchronizing signal detector 7 or the pseudo horizontal synchronizing signal generator 8. The vertical position of one screen is shown.Here, the storage position of image information in the present invention will be described as follows.

That is, the vertical position is determined by counting the water motion synchronization signal in the 11f raw video signal, and the horizontal direction is determined by the accurate lock signal. As a result, one pixel on the screen is stored and read out in correspondence with one element on the memory. Next, the operation of the FG generator 14 and the like will be explained. As in the prior art described above, when the magnetic tape 1 is driven in synchronization with the rotation of the drum motor 6, the position of the noise on the screen is fixed. That's where this noise comes from.

Missing portions of the signal are previously reproduced and replaced with information stored in the image memory 11. For this reason, it is determined which parts are noise and which parts are not, and the following processing is performed for each part.

0 Non-noise portion 9 Stored in image memory and output on both sides at the same time.

(write) O size part → Read from both image memory.

There are several methods for making this determination, but in the embodiment shown in Figure 1, the DF generated by reflecting the rotation of the drum
A configuration is shown in which the above-described partial discrimination is performed using the G signal. In other words, the time period during which the rotary head on the drum is in contact with the magnetic tape corresponds to the scanning time of the television screen, and the position of noise on one screen can be determined by monitoring the rotational phase of the drum. This situation can be explained in the supplementary explanatory diagram of FIG. 4 as follows. Figure 4 (1) shows the reproduced TV screen, (2) shows the rotation of the drum and the magnetic tape, and (3) shows the DF.
It is a G signal.

Now, when the head on the drum rotates from point A to point B in FIG. 4(2), the television screen is scanned by one screen (from A to DB). Further, an example of the DFG signal at this time is shown in FIG. 4(3). Then, the middle part of the screen (Figure 4 (1)
)C), the rotary head is at (2)C in FIG. 4, which is near C (3) in FIG. 4 when looking at the DFG. Although not shown in this example, there is a DFG on the drum.
In addition to this, a generator for a signal indicating the rotational phase of the drum is generally provided.
The position of the scanning point on the screen can be clearly detected. In this example,
For example, the rotary phase signal generator is provided near point A,
This output signal is used to reset the DFG signal every time.
The scanning point on the screen can be detected in certain increments (DFG increments) using the counter.

According to the example in Fig. 4 (3), there are three periods of D in half a rotation of the drum.
Since FG is generated, three sections on the television screen shown in FIG. 4(1) can be detected. Furthermore, by making the increments of this DFG finer or by adding an appropriate delay circuit to the output of the o+;'a signal counter, it is possible to freely detect the section of TV screen points. The above is the detection of the area 1711 on the screen using the DFG signal, but there is also a method of selecting the above two processes (memory writing, reading) etc. based on the playback output level of the one-rotation head. It will be done. An example of this configuration is shown in FIG. In the figure, 60 is an envelope detector, 61 is a constant voltage source, and 62 is a voltage comparator. In this configuration, if the reproduced signal is envelope-detected and this signal is compared with the level of the constant voltage source, the reproduced level will be low for the noise part and high for the other parts, so the level can be determined according to the output of the voltage comparator. It is possible.

According to the judgment signal of the noise part and the non-noise part to the north,
Switch the changeover switches 16 and 17 in FIGS. 1 and 5. The procedure is as follows: ○ Noise part → Switches 16 and 17 are on the b side O Other parts → Switches 16 and 17 are on the a side. Here, the switching of the switch 17 switches between the horizontal synchronizing signal reproduced from the magnetic tape and the horizontal synchronizing signal generated in a pseudo manner. The reason for this is that since the horizontal synchronization signal is disturbed in the noise part, reading from the image memory must be performed in accordance with the pseudo horizontal synchronization signal generated by counting the correct lock from the clock generator 9, etc. be. Here, a concrete configuration of the pseudo vertical synchronizing signal generator 8 is shown in FIG.

In FIG. 6, 70 is a counter, 71 is a logic signal, and 72
．． 73 is an AND gate, 74 is an OR-I-, 75 is an inverter, and 76.77 is a voltage signal. The operation of this configuration will be described below. first.

If the output of the switching signal generator 15 or the voltage comparator 62 is high, indicating the reproduction of the noise part, and low, indicating the reproduction of the non-noise part, when there is a signal of 760, the analog gates 1 and 73 are closed, and the horizontal synchronizing signal detector 7 The output of AND gate 72
．． It is applied via an OR gate 74 as a preset pulse to the counter 7o. At this time, the counter 70 continues to operate in synchronization with the output from the horizontal synchronization signal detector 7, that is, the horizontal synchronization signal in the reproduced video signal, while counting the clock from the clock generator 9. . Next, when the noise portion is reproduced and the signal 76 is inverted to high, the AND gate 72 is closed and a preset pulse is applied to the counter via the AND gate 73. At this time, the logic circuit 71 operates to generate a preset pulse for the counter 70, and repeats the counting operation at a period corresponding to the horizontal synchronization period. By this operation, even when the noise portion is reproduced, the horizontal synchronizing signal can be continuously obtained, and by applying this signal to the address generator 10, reading from the image memory is performed without any delay.

Next, the operation of the phase comparator 13 and the like will be explained. Although the above-described configuration can cover an excessive state of switching from a non-noise part to a noise part, conversely, some problems occur in an excessive state of switching from a noise part reproduction to a non-noise part. This is performed by the counter 70 and the logic circuit 71 periodically.
~The cycle of repeating the operation is set in advance to the horizontal synchronization signal cycle during playback, but due to fluctuations in playback speed, etc., the counter itself generates a pseudo horizontal synchronization signal and noise. A slight phase shift occurs between the detected horizontal synchronization signal and the horizontal synchronization signal when the parts that are not displayed are reproduced again, and the seam of the screen becomes curved. In order to prevent this and make a normal seam, a phase comparator 13 and a motor driver 20 are used.
The horizontal synchronization signals of both sides are phase-aligned by controlling the motor through the . A specific configuration of this phase comparator 13 is shown in FIG. 7, and a waveform diagram of its essential parts is shown in FIG. Here, 80 is a sampling pulse generator, 8 is a trapezoidal wave generator, 82 is a sampling hold circuit, and 83 to 86 are voltage signals. First, the pseudo horizontal synchronizing signal 83 triggers the trapezoidal wave generator 81 to generate one trapezoidal wave 84. On the other hand, the sampling signal 8 is processed by the reproduced horizontal synchronizing signal and shaped into an appropriate pulse width by the sampling pulse generator.
5 is a sampling and holding circuit 82 which samples and holds the trapezoidal wave 84 and outputs a signal 86. As a result, when the phase of the reproduced horizontal synchronization signal 83 lags behind that of the pseudo horizontal synchronization signal, the sampling hold output 86 increases. Upon receiving this, the motor driver 20 causes the drum motor to rotate at high speed, and reproduces the horizontal synchronization signal 83.
advance the phase of Through this control, the pseudo horizontal synchronization signal and the reproduced horizontal synchronization signal have a constant phase.

According to the above control, the configuration of this embodiment enables noiseless two-head quick playback using the image memory.

〔Effect of the invention〕

According to the present invention, noise-free quick playback, which conventionally could not be achieved without adding many rotary heads and significantly increasing cost in magnetic recording and reproducing devices, is achieved by replacing the special playback head with a semiconductor element called image memory. By replacing it, a high-quality image can be achieved without any curvature (distortion) of one screen, which not only has the effect of improving performance, but also has the effect of reducing costs.

4 ff1f’li explanation of the drawing FIG. 1 is a block diagram showing one embodiment of the present invention.

FIGS. 2, 3, and 6 are block diagrams showing an example of the structure in the embodiment, and FIG. 4 is a waveform diagram of main parts of the components shown in FIG.

7...Horizontal synchronization signal generator, 8...Pseudo horizontal synchronization signal generator, 10...Address generator.

11... Image memory

Claims (1)

[Claims] 1) In a helical scan type magnetic recording and reproducing device, phase control is performed so that the rotary head traces the recording pattern on the magnetic tape at n times the recording speed (n is an integer of 2 or more). means for converting the reproduced information of the rotary head into a digital quantity; a storage means for storing the converted digital quantity; a means for converting the output of the storage means into an analog quantity; 1. A magnetic recording and reproducing apparatus, comprising a selection means for selecting a read signal from a storage means that has been previously reproduced by an opposing rotary head and stored in the storage means. 2) In the magnetic recording and reproducing apparatus according to claim 1, the selection control means for controlling the selection of the selection means described above is comprised of an envelope detection means for the rotary head output and a level comparison means for the envelope detection output. A magnetic recording/reproducing device characterized by comprising: 3) A magnetic recording and reproducing apparatus characterized in that the selection control means according to claim 2 is constituted by rotational phase detection means of a rotary head or means for delaying the output of the rotational phase detection means. 4) In the device according to claim 1, a constant frequency signal generating means for generating a constant frequency and a synchronizing means for performing writing and reading of the above-mentioned storage means in synchronization with the generated signal are added. A magnetic recording and reproducing apparatus further comprising presetting means for presetting the synchronizing means by a horizontal or vertical synchronizing signal reproduced from a rotary head. 5) In the device according to claim 4, the phase difference between the output of the constant frequency signal generating means and the horizontal synchronization signal reproduced from the rotary head is detected, and the rotational speed of the rotary head is adjusted according to the phase difference. A magnetic recording/reproducing device characterized in that it is provided with a correction means for correction.