JPS6363292A - Special reproduction circuit - Google Patents

Abstract

PURPOSE:To restructure a correct muse signal even in a special reproduction operation by adjusting a horizontal scan signal period for a reproduced muse signal and correcting said muse signal right before a control signal following a final field video signal so that the number of horizontal scan signals included in a vertical scan signal in one field never increases or decreases by the jumping scan of a recording track. CONSTITUTION:A read address signal B synchronizing with a correct clock X'CLK without a jitter component reads a digital reproduced signal written in a memory 5 at a precise timing. If there are a lot of Hs, the signal B instructs to jump data during a period DELTAH right before the control signal, thereby reducing and reproducing excessive signals. If there are a few Hs the memory 5 stops its read action during the period DELTAH right before the control signal. During that period, an additonal data generator 7 outputs additional data to a cut piece gamma in an output signal selection switch 8. As for the reproduced signal in the special reproduction operation, the number of Hs in 1V is equal to that in a normal reproduction operation. After the reproduced signal is made into the correct muse signal, a D/A converter 9 returns the muse signal to an analog signal under the correct cycle of the X'CLK, and outputs it to a muse signal demodulator from a terminal 10.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to a VTR (video tape recorder) that records and plays back a MtJSE band-compressed video signal.
The present invention relates to a circuit for special playback (fast forward playback, slow playback, 9 rewind playback, still image playback, etc.).

(Prior art) Figures 2 and 3 show the head trace pattern during special playback of a VTR that is currently in general use and performs helical scanning with two heads to record and play back images. n) Indicated by (shaded area). FIG. 2 shows a head trace pattern during fast-forward playback, and FIG. 2(a) shows two-speed playback when one track constitutes one field (m=1).

(n-2), and Fig. 2 (1)) shows three-way speed playback (m=1) when one field is formed in one track at t3.

The same applies to the double speed (m=2.n=2) when one field is composed of two tracks. Third
The figure shows a head trace pattern during rewinding and still image playback, and Fig. 3 (a> is 1x speed rewinding when one track constitutes one field, m = i, n = -1) FIG. 3(b) shows still image reproduction when one track constitutes one field (m=1.m=o). here,
Vv is the tape running direction, and ■8 is the head scanning direction.

al, bl, a2, b2, and a3 indicate recording patterns damaged by the two heads (a, b) on the tape 11 during recording. As shown in Figures 2 and 3,
During special playback, the length traced by the head changes depending on the relative speed with the tape.

It becomes shorter when moving the mochi, and becomes longer when stopping and rewinding. Due to this change in length, the number of horizontal scanning signals H included therein also changes, and the number ΔH is expressed using αto1 (the deviation of the horizontal synchronizing signal between adjacent tracks). As an example, α1 of the β■ method is 0.75)-1. That is, when the number of rotations of the rotary head is the same as during normal reproduction, the amount of change ΔH in the number of H's included in the vertical scanning signal 1V of one field during special reproduction can be expressed by the following equation.

ΔH=-m (n-1) XαH *m: Number of tracks required to reproduce one field n: Indicates speed. Fast forwarding is written as 9. Rewinding is written as 9. When at rest, it is 0.

In an NTSC TV, the allowable range for the period of 1 is narrow in the input signal, but the allowable range for the period of 1 is wide. Also, l
The number 1-1 in V does not particularly affect the image.

Therefore, VTRs that record and reproduce NTSC signals do not need to take any special measures against ΔH by changing the rotational speed of the cylinder during special playback and adjusting only the 1-1 cycle.

However, when recording a signal that has been subjected to band compression processing such as the so-called Meuse method proposed by NHK (Japan Broadcasting Corporation) on a helical scan method VTR and performing special playback, not only the period of the horizontal scanning signal H but also the , if the number of H included in one field of vertical scanning @number 1■ is not correctly reproduced, it will be difficult to restore the band compressed signal to the original @number. Figure 4 shows the structure of 1 of the Meuse system.

The two color signals Cv and CN are 1/4 of the luminance signal Y.
The time axis has been compressed and further transformed into line-sequential. Further, the phase of the horizontal synchronization signal HD is inverted for each line. Furthermore, since screen movement information and the like are included in the control section, when reproducing the VF signal, accurate reproduction cannot be achieved if these signal configurations increase, decrease, or differ.

(Problems to be Solved by the Invention) The present invention has been made in consideration of the problem that in the prior art, there was a risk of trouble in restoring the muse signal to the original signal during special playback. It is an object of the present invention to make it possible to reconstruct a correct Muse signal even during special playback using the circuit V4, thereby realizing special playback and providing a blue special playback circuit.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention enables fast forward playback and slow playback of a medium on which a Muse signal is recorded.

In circuits that perform special playback such as rewind playback and still image playback, the period of the horizontal scanning signal of the reproduced Muse signal is adjusted, and the number of horizontal scanning signals included in one field of vertical scanning signals is adjusted so that the number of horizontal scanning signals exceeds the recording track. This method is characterized by adjusting the signal structure by correcting the increase or decrease caused by scanning immediately before the control signal located at the end of each field video signal.

(Function) The present invention uses the above means to position the control signal at the end of the Y and C@ numbers of each field, and immediately before the control number 14, the loss of the TO 1 changed by the special playback is detected by -Δ
By adding or subtracting l-1, the number of H included in 1V of the playback signal is adjusted, so that the video information in the Muse signal is exactly 1 even during special playback, and the same as the signal during normal playback. Since it can be sent with the collar open, it is possible to prevent malfunctions at the receiver.
n You can view special playback images without any problems. Also, 1■
By adjusting the number of 1's included in the image immediately before the control signal, it is possible to make corrections at the last position of the image in each field without changing the control position within one field. It has less influence and is also easy to modify.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of an actual tJ color according to the present invention. This protrusion is a part that performs time axis correction of the reproduced signal, and in this embodiment, the υJII] signal generator 6. Additional data generator7.
This can be realized by adding an output signal selection switch 8.

That is, the muse playback signal from the VTR is sent from terminal 1 to A/
The signal is input to the D converter 4 and added from the terminal 2. VTR
is converted into a digital signal using a regenerated clock that reflects the time axis fluctuations of the signal. Further, a digital signal is sent to and from a random access memory (RAM>5) by a write address signal (A) generated in synchronization with the clock. At this time, a digital reproduction signal is also sent to a control signal generator 6.

The RJJ m signal @ generator 6 selects whether or not addition/deletion of the above-mentioned Δl is necessary based on a logic signal inputted from the terminal 3. Then, when addition is necessary, the data of the additional signal (C) and the generation timing of the additional @ signal <D>
is sent to the additional data generator 7.

This additional data is based on the 1-10 signal determined from the day before and after,
It consists of appropriate Y and C signals which become one interpolation report.

The digital playback signal written in the memory 5 is read out at accurate timing by a read address signal @(B) synchronized with accurate lock X'cLK without jitter components. At this time, if there are many H's, the read address signal (B) serves as an instruction to skip the data in the period of ΔH immediately before the control signal, thereby reducing the excessive signal by ΔH and reproducing it. Moreover, when H is small, the memory 5 stops the read operation for a period of ΔH immediately before the control signal. During that period, the additional data generator 7 outputs additional data to the output @@ the intercept γ of the selection switch 8 .

Further, the switch 8 switches from the intercept β to the intercept γ only during that period. The above operations are executed simultaneously because the read address signal (B) generated from the control signal generator 6 and the control timing signals (D) and (E) are synchronized, so the reproduction signal is transmitted during the period of ΔH. continuous signal insertion is performed.

Through the above procedure, the playback signal during special playback is configured into a correct Muse signal by adjusting the number of H's in 1 to be the same as during normal playback, and then converted to X' by the D,/A converter 9.
The signal is returned to an analog signal at the correct period of K, and is output from terminal 10 to the Muse signal demodulator.

As described above, the circuit of this embodiment controls the control I@ signal generator 6, the additional data generator 7, and the output signal selection switch 8 at the time iPI!! This can be achieved by simply adding it to the correction circuit. That is, in the circuit that performs time axis correction of the Muse playback video signal, there are a control signal light source that controls writing and reading of video information to and from memory (RAM), and an additional data generator that generates additional data from the input signal. and a switch for selecting additional data and read data.
When the number of -1 is increasing, when reading from the memory, the signal immediately before the control is deleted by the increasing number (increasing) and read out, and when it is decreasing, reading from the memory is paused just before the control, and the signal is added. By changing the switch and additionally inserting the additional data generated from the data optical generator, the MUSE signal's @ composition is not lost even during special reproduction. The operation of this circuit makes it possible to reconstruct the correct Muse signal even during special playback, thereby realizing special playback. The screen information that is added or deleted is located at the bottom corner of the screen, so even if it is corrected, it will not be noticeable at all.

[Effects of the Invention J As described above, according to the present invention, it is possible to reconstruct a correct Muse signal even during special playback with a simple configuration.
Therefore, it is possible to provide a special playback circuit that can realize special playback.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention, WS2 and 3 are diagrams showing an example of a head trace pattern during special playback of a VTR, and FIG. 4 is an explanatory diagram showing a signal configuration of the Meuse system. It is a diagram. 4... A/D converter, 5... RAM, 6... Control signal generator, 7... Additional data generator, 8... Output signal selection switch, 9... D/A converter.

Claims (1)

[Claims] In a circuit that performs special reproduction such as fast forward playback, slow playback, rewind playback, and still image playback of a medium on which a Myuse signal is recorded, the period of the horizontal scanning signal of the reproduced Myuse signal is adjusted, and the vertical scanning signal of one field is The present invention is characterized in that the number of horizontal scanning signals included in the field video signal increases or decreases due to skipping scanning of recording tracks, and the signal configuration is adjusted by correcting the increase or decrease immediately before the control signal located at the end of each field video signal. Special regeneration circuit.