JP3082281B2 - Signal processing circuit of video signal playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing circuit of a video signal reproducing apparatus which is suitably applied to, for example, a time axis correcting apparatus of a video signal reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, in a video signal reproducing apparatus of a beta cam format, a video signal in which a chroma signal and a luminance signal are component-recorded separately on a tape by four heads is reproduced. I have to. The recording format is as shown in FIG.
Shows the case of the NTSC system, and FIG. 12B shows the case of the PAL or SECAM system. As shown in FIG. 12A, in recording an NTSC video signal, a luminance signal Y and a chroma signal are alternately recorded on a recording surface of a tape with different azimuth angles. The video track angle θ is 4.6790, the track width C of the chroma signal is 71 to 75 μm, the track Y track of the luminance signal Y and the chroma signal C
Of the track C between tracks 78.5 to 82.
5 μm, and the lower edge of the video track is 880 μm to 10 μm.
The width N of the track Y of the luminance signal Y is 71 μm to 75 μm, and the overlap O is 2 μm.
The track offset P between the track Y track of the luminance signal Y and the track C track of the chroma signal C is 4399 μm, the video track pitch Q is 161 μm, and the control head distance S is 366 μm.
00 to 36800 μm, and the audio head distance T
Is set to 180903 to 18933 μm, and the lower limit Y of the effective video width W is set to 1233 to 1258 μm. Also,
As shown in FIG. 12B, in the recording of the video signal of the PAL or SECAM system, the overlap O is 2391 μm.
m, and the track offset P between the track Y track of the luminance signal Y and the track C track of the chroma signal C is 4
399 μm, and the video track pitch Q is 166 μm.
m. The other components are the same as in the case of recording the NTSC video signal. Among the video signals component-recorded in this way, the luminance signal Y is F
After M demodulation and de-emphasis, signal processing such as time axis correction is performed. On the other hand, the chroma signal is RY, BY
Since the data is compressed and recorded by で, it is expanded twice in the reproducing system, and is encoded after signal processing such as time axis correction is performed.

[0003] This time axis correction is performed by converting a reproduced video signal into an A-D signal.
The digital data is converted into digital data by a converter, and this digital data is written to a memory with a write clock using a write phase reference signal formed based on a reproduction synchronization signal separated from a reproduction video signal, and the read phase reference signal is read. This is performed by reading digital data written in the memory with a read clock as a phase reference. At the same time, after the later-described dropout processing and gray replacement processing are performed,
The luminance signal Y and the chroma signal C are mixed and supplied to a monitor or the like as a color video signal. When the video signal is reproduced by such a video signal reproducing apparatus, a loss of the reproduced video signal, that is, a so-called dropout may occur. When this dropout occurs, the dropout is detected by a circuit for detecting the dropout, and the dropout signal is used to interpolate the dropout portion of the video signal with the preceding data. When performing a so-called search operation for reproducing at a higher speed than the normal reproduction speed, a guard band is detected by a dropout signal, and a video signal corresponding to the detected guard band is gray-replaced by a so-called gray-replacement process. And output it. In guard band detection, the period of the falling edge of the reproduced horizontal synchronizing signal is determined by dividing the read clock by half.
Counting is performed using the frequency-divided signal obtained by frequency division to obtain average horizontal cycle data for reproduction. Based on the average horizontal cycle data, the next falling edge of the reproduction horizontal synchronization signal is predicted. And
Based on the prediction, an average period detection signal is generated, and the average period detection signal is latched with a reproduced horizontal synchronization signal guarded by a dropout signal to form a guard band signal. Then, based on the guard band signal, the video signal corresponding to the guard band portion (low level “0”) is
So-called gray replacement processing is used to perform gray replacement and output.

As shown in FIG. 13A, when a dropout of three horizontal periods occurs in a reproduced video signal during reproduction,
4, 5, and 6 lines of the reproduced horizontal synchronizing signal are missing. The GH signal at this time is as shown in FIG. 13B. The dropout signal is as shown in FIG. 13C. At this time, since the guard band signal is formed using the reproduced horizontal synchronizing signal as a clock, if the reproduced horizontal synchronizing signal is lost as shown in FIG. Becomes a high level "1", and a reproduced horizontal synchronizing signal appears.
The guard band is released at the ninth line of the reproduced horizontal synchronizing signal, that is, the GH signal at which the guard band becomes a low level “0” at the line 9 and the GH signal is output,
It becomes high level "1". In this case, the originally appropriate guard band signal is as shown in FIG. 13F. Therefore, a part that should originally be a guard band during the gray replacement processing is not determined to be a guard band, and the gray replacement processing is not performed. Therefore, the OR signal obtained by ORing the dropout signal and the guard band signal is used as the guard band signal. Further, at the time of reproduction by a search operation at a speed of ± 30 times or more, the reproduced horizontal synchronizing signal is used as a GH signal, and all the low level “0” portions of the guard band signal are replaced with gray.

[0005]

Conventionally, the low-level "0" portion of the guard band signal is determined to be a gray replacement process portion. Even when there is a horizontal period or more, the reproduced video signal corresponding to this portion is gray-replaced and supplied to a monitor or the like. Therefore, there is a disadvantage that an image on the screen of the monitor is very difficult to see. In addition, during reproduction by a high-speed search operation of ± 30 times or more, since the reproduced horizontal synchronizing signal is a GH signal, the guard band signal has many low-level “0” parts, and all the guard band parts are replaced with gray. Therefore, gray portions are increased in an image projected on a screen of a monitor or the like, and there is a disadvantage that an image is very difficult to see. Furthermore, beta
In the cam system, the write phase reference in the search operation is, for example, as shown in FIG. 8 due to the azimuth in the tape format. At this time,
The image projection state on the tube surface is, for example, as shown in FIG.
You. In FIG. 9 , the numerals 1 to 8 described on the left correspond to the numerals 1 to 8 described in the reproduced horizontal synchronization signal of FIG. 8A, respectively. Further, d is a dropout portion, which corresponds to the dropout portion shown in FIG. 8C, and g is a guard band portion, which corresponds to the guard band portion shown in FIG. 8D. As shown in FIG. 8, for example, when there is a dropout (FIG. 8C) from line 2 to line 6 of the horizontal synchronizing signal of the reproduced video signal, the reproduced horizontal synchronizing signal cannot be taken from line 3 to line 6. . At this time, the guard band portion corresponds to three to six lines of the reproduced horizontal synchronization signal as shown in FIG. 8D. Therefore, FIG.
As shown as tx in B, writing is not performed for a predetermined amount. At this time, after reading from the memory 57,
When a video signal is displayed on the screen of a monitor or the like without performing the gray processing on the lead side, as shown in FIG. 9, a predetermined portion where writing has not been performed is displayed as previously written data tx. It is. If the memory 57 is a so-called line memory, the data tx moves on the screen of the monitor, and there is a disadvantage that the image becomes very hard to see visually.

The present invention has been made in view of the above points. For example, when the present invention is applied to a time axis correction device of a video signal reproducing device, it is possible to minimize the gray replacement at the time of a search operation and to realize a so-called image. An object of the present invention is to propose a signal processing circuit of a video signal reproducing apparatus capable of displaying an extremely high-quality image without causing disturbance.

[0007]

A signal processing circuit of a video signal reproducing apparatus according to the present invention comprises a horizontal period detecting signal for detecting a horizontal period of a reproduction synchronizing signal based on a reference signal as shown in FIGS. , A horizontal cycle detection signal from the horizontal cycle detection signal generators 4, 5, 8, 9, 10 and 11 and a reproduction synchronization signal. a detection signal generating means 12 for generating a detection signal based on bets, the detection signal generating means 12
If the detection period of the detection signal exceeds at least two horizontal periods, the start 1
The part of the reproduced video signal corresponding to the horizontal period is interpolated with the information before the reproduced video signal corresponding to one horizontal period beginning of the detection period of the detection signal, and the detection period of the detection signal is detected.
Of playback video signals corresponding to other than one horizontal period
Compensation means 55, 57, 58,
59 and 60 .

[0008]

According to the present invention described above, the detection signal generating means 1 is provided.
2 is a horizontal cycle detection signal from horizontal cycle detection signal generation means 4, 5, 8, 9, 10 and 11 for generating a horizontal cycle detection signal for detecting a horizontal cycle of the reproduction synchronization signal based on the reference signal. If the detection period of the detection signal generated based on the reproduction synchronization signal extends for at least two horizontal periods, the compensating means 55, 57, 58, 59, and 60 set the detection period of the detection signal for one horizontal period. Is interpolated by the information before the reproduced video signal corresponding to one horizontal cycle at the beginning of the detection period of the detection signal, and one horizontal cycle at the beginning of the detection period of the detection signal.
The gray scale is used to replace the part of the reproduced video signal corresponding to other than the above.For example, when the present invention is applied to a time axis correction device of a video signal reproducing device, the minimum gray replacement at the time of a search operation is performed. As a result, an extremely high quality image can be displayed without causing so-called image disturbance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a signal processing circuit of a video signal reproducing apparatus according to the present invention will be described below in detail with reference to FIGS. First, the synchronization signal detection circuit 53 shown in FIG. 1 will be described with reference to FIG. In FIG. 2, reference numeral 1 denotes an input terminal to which a read clock is supplied, and a read clock from the input terminal 1 is supplied to a frequency dividing circuit 4 and a timer to be described later .
Imming generator 8 and average pulse width detection circuit 17
Respectively . The frequency dividing circuit 4 divides the read clock from the input terminal 1 by 例 え ば, for example, and divides the ク ロ ッ ク frequency of the read clock (hereinafter simply referred to as a frequency-divided signal) into a horizontal period count circuit. 5 is being supplied. The horizontal cycle counting circuit 5 counts the period of the falling edge of the reproduced horizontal synchronizing signal (see FIG. 3A) using the reference signal from the frequency dividing circuit 4, and outputs the horizontal cycle data signal obtained by this counting to a timing generator 8 described later. It is supplied to the average horizontal period detection circuit 10 by the load signal. The average horizontal cycle detection circuit 10 receives a horizontal cycle data signal from the horizontal cycle count circuit 5 and an average horizontal cycle latch data signal from an average horizontal cycle data latch circuit 9 described later based on a switch signal from the timing generator 8. , And as a result, an average horizontal cycle data signal is obtained and supplied to the average horizontal cycle data latch circuit 9 and the average cycle detection signal generation circuit 11, respectively.
The average horizontal cycle data latch circuit 9 smoothes the average horizontal cycle data signal from the average horizontal cycle detection circuit 10 based on a sample hold signal from the timing generator 8, and converts the smoothed average horizontal cycle latch data signal. Supply to average horizontal period detection circuit.

The average period detection signal generation circuit 11 is configured to generate a signal based on a reset signal from the timing generator 8.
An average period detection signal (FIG. 3B , FIG. 4) in which pulses of, for example, ± 1 μs are set before and after the predicted arrival position of the falling edge of the next reproduced horizontal synchronization signal from the average horizontal period data signal from the average horizontal period detection circuit . And FIG. 5 ) .
The average period detection signal is supplied to the gate circuit 12 and an average period detection circuit 13 described later, respectively. This gate circuit 1
2 gates a guard sync signal from a gate circuit 7 to be described later with an average period detection signal from an average period detection signal generation circuit 11 to obtain a gated guard sync signal. Contact 14a
, And latches the average period detection signal at the falling edge of the guard sync signal from the gate circuit 7 to generate a first guard band signal (see FIG. 3G). This first guard band signal will be described later. The signal is supplied to the mix guard band signal generation circuit 20.

Here, the above-mentioned guard sync signal will be described. Reference numeral 2 denotes a dropout signal detected in the reproduced RF signal (a signal in which a dropout of the reproduced video signal is detected)
The dropout signal supplied to the input terminal 2 is supplied to a dropout stretch circuit 6. This dropout stretch circuit 6
Expands the trailing edge of the dropout signal supplied through the input terminal 2 by, for example, 2 μs, and supplies the dropout signal (see FIG. 3E) with the trailing edge extended to the gate circuit 7 and a phase detection circuit 18 described later, respectively. I do. 3
Is an input terminal to which a reproduced horizontal synchronizing signal is supplied. The reproduced horizontal synchronizing signal supplied to this input terminal 3 is supplied to a gate circuit 7. The gate circuit 7 gates the reproduced horizontal synchronizing signal from the input terminal 3 with the dropout signal from the dropout stretch circuit 6. As a result, the above-mentioned guard sync signal is generated. The guard sync signal from the gate circuit 7 is supplied to the timing generator 8, the gate circuit 12 and the switch 14 already described above.
Are supplied to the other fixed contact 14b and the average period detecting circuit 13 described later. As described above, the timing generator 8 generates a load signal, a switch signal, a sample-and-hold signal, a reset signal, and the like based on the guard sync signal from the gate circuit 7 and the frequency-divided signal from the frequency-divider circuit 4. The average period detection circuit 13 latches the guard sync signal from the gate circuit 7 at the falling edge of the average period detection signal from the average period detection signal generation circuit 11 to obtain a second guard band signal (see FIG. 3H). The second guard band signal is supplied to the mixed guard band signal generation circuit 20.

The switch 14 changes the movable contact 14c of the switch 14 to one fixed contact 14a or the other fixed contact 14a in response to a mode signal supplied to the control input terminal 15 and becoming "0" at a speed of, for example,. +-. 30.times. The switch 14 is connected to a gated guard sync signal supplied to one fixed contact 14a of the switch 14 or a guard sync signal supplied to the other fixed contact 14b of the switch 14 by a GH signal (G is a gate , H are supplied to an output terminal 16 as horizontal synchronizing signals, and are also supplied to an average pulse width detection circuit 17 described later. The average pulse width detection circuit 17 outputs the gated guard sync signal or guard sync signal from the switch 14, ie, GH
The average pulse width of the signal (see FIG. 3F) is detected based on the read clock from the input terminal 1, and the detected value (count value) is used, for example, ± 0.5 μs before and after the predicted rising edge of the next GH signal. , A pulse width detection signal (see FIG. 4) is obtained .
A third guard band signal (see FIG. 2I) is generated by latching at the rising edge of the H signal, and the third guard band signal is supplied to a phase detection circuit 18 and a mixed guard band signal generation circuit 20, which will be described later.

The phase detection circuit 18 generates a phase detection signal for extracting an edge serving as a phase reference, and at the falling of the phase detection signal, the dropout stretch circuit 6
The fourth guard band signal (see FIG. 3J) is obtained by latching the drop-out signal from the input terminal, and the fourth guard band signal is supplied to the mixed guard band signal generation circuit 20 and the generated phase detection signal is output to the output terminal 19. To supply. The mixed guard band signal generation circuit 20 includes a first guard band signal from the gate circuit 12, a second guard band signal from the average period detection circuit 13, a third guard band signal from the average pulse width detection circuit 17, and a phase detection circuit. The AND of all the fourth guard band signals is taken, a mixed guard band signal is generated, and this mixed guard band signal is supplied to the output terminal 21.

Next, the operation of the above-described synchronization signal detecting circuit will be described with reference to the timing chart of FIG.
In FIG. 3, for example, as shown in FIG. 3E, assuming that dropout occurs over 3H (horizontal period), the reproduced horizontal synchronizing signal is 4, 5 as shown in FIG. 3A.
And the sixth is missing. At this time, in the gate circuit 12, since the average period detection signal is latched at the falling edge of the guard sync signal from the gate circuit 7, the fourth, fifth and sixth reproduction horizontal synchronization signals are pre-held and the guard band Will not be determined. Therefore, as shown in FIG. 3G, the first guard band signal from the gate circuit 12 becomes a low level “0” which is the guard band at the seventh of the reproduced horizontal synchronizing signal, and the GH signal shown in FIG. When the gated guard sync signal output from the circuit 12 starts to fall, the ninth of the reproduced horizontal synchronizing signal becomes a high level "1" at which the guard band is released.

As described with reference to FIG. 2, this gated guard sync signal is formed as follows. That is, a load signal based on the guard sync signal from the gate circuit 7 is formed by the timing generator 8,
Until the count value is loaded by this load signal,
The horizontal cycle counting circuit 5 counts the frequency-divided signal (frequency-divided signal of the read clock) from the frequency-dividing circuit, thereby counting the period of the falling edge of the reproduced horizontal synchronizing signal. Then, this count value is smoothed by the average horizontal cycle data latch circuit 9 and the average horizontal cycle detection circuit 10, and is used as average horizontal cycle data. Then, the average period detection signal generation circuit 11 predicts the arrival position of the next rising edge of the reproduced horizontal synchronization signal from the average horizontal period data, and generates an average period detection signal ( ± 1 μs pulse before and after ). 4 and 5) . Further, the guard sync signal is gated by the average period detection signal. A guard sync signal gated in this way is formed. Further, in the present example, in the reproduction mode at ± 10 × speed or lower, unless the guard sync signal is continuously included in the pulse portion of the average period detection signal, the gate sync signal is not formed.
Accordingly, as shown in FIGS. 3F and 3A, the portion corresponding to the eighth of the reproduced horizontal synchronization signal of the GH signal is active,
That is, it does not become low level “0”.

As shown in FIGS. 3H and 3B, the second guard band signal is supplied to the average period detection circuit 13 by a guard sync signal from the gate circuit 7 at the falling edge of the average period detection signal from the average period detection circuit 11. It is formed by being latched. Now, since the phase reference of the luminance signal Y in the beta cam format is the rising edge of the reproduced horizontal synchronizing signal, the GH obtained based on the average horizontal period of the rising edge of the reproduced horizontal synchronizing signal as in the related art. As shown in FIGS. 3A and 3F, some of the signals include those in which the rising edges are cut off by dropout in the eleventh and fifteenth portions of the reproduced horizontal synchronizing signal. Was the cause. Therefore, the third guard band signal is obtained by detecting, as a guard band, a state in which the trailing edge of the reproduced horizontal synchronizing signal has been removed by dropout, and this third guard band signal is, as shown in FIGS. The pulse width detection signal (see FIG. 4) generated by the average pulse width detection circuit 17 is formed by latching at the rising edge of the guard sync signal from the gate circuit 7. That is, as shown in FIG. 3F, the average pulse width detection circuit 17 detects the pulse width of the low level “0” section of the GH signal from the switch 14 and counts it with the clock to detect the average pulse width of the GH signal. The arrival position of the next rising edge of the GH signal is predicted from the count value, and ± 0.5 μs before and after the corresponding portion.
Make a pulse. Then, as described above, the pulse width detection signal generated by the average pulse width detection circuit 17 (FIG. 4)
3) is latched at the rising edge of the guard sync signal from the gate circuit 7, so that the line of the edge (corresponding to the eleventh of the reproduced horizontal synchronization signal) eroded by the dropout in the GH signal as shown in FIG. 3I. ,
Make it a guard band.

On the other hand, the fourth guard band signal also detects a state in which the trailing edge of the reproduced horizontal synchronizing signal has been removed by dropout as a guard band. The fourth guard band signal is shown in FIGS. 3D and 3J. Thus, the dropout signal from the dropout stretch circuit 6 is latched at the rising edge of the phase detection signal (see FIG. 4) generated by the phase detection circuit 18. This is because an edge (corresponding to the fifteenth reproduction horizontal synchronization signal) of the GH signal which cannot be detected by the pulse width detection circuit 17 described above occurs. Accordingly, the phase detection signal generated by the phase detection circuit 18 (FIG. 4)
Drop-out stretch circuit 6 at the rising edge of the reference)
Latching the dropout signal from
The line of the edge (corresponding to the fifteenth reproduction horizontal synchronization signal) eroded by the dropout in the H signal is set as a guard band as shown in FIG. 3J.

Thus, the first to fourth guard band signals are formed. Here, since the above-mentioned average period detection signal is a signal that predicts the arrival position of the guard sync signal, as shown in FIGS. 3A and 3B, if there is a third horizontal synchronizing signal in the reproduced horizontal synchronizing signal, An average period detection signal is set in a portion corresponding to the next fourth. Accordingly, the portion corresponding to the fourth portion of the reproduced horizontal synchronizing signal can be determined as a guard band, and a second guard band signal can be formed as shown in FIG. 3H. However, as shown in FIGS. 3A and 3H, the guard band is released in the portion corresponding to the eighth portion of the reproduced horizontal synchronization signal. Therefore, it is necessary to AND the first guard band signal and the second guard band signal shown in FIG. 3G. Also, it is necessary to perform an AND operation on the third and fourth guard band signals. Therefore, in the mix guard band signal generation circuit 20 shown in FIG.
The fourth guard band signal is ANDed to generate a mixed guard band signal as shown in FIG. 3K. The mix guard band signal generation circuit 20 includes a control signal from the input terminal 15, an average period detection signal from the average period detection signal generation circuit 11, a signal indicating the tape running direction from the video signal reproducing apparatus main body, and a chroma signal. A signal for performing switch control with the signal C and the luminance signal Y,
FIG. 6 shows and describes the signal lines of the guard sync signal from the gate circuit 7 and the dropout signal from the dropout stretch circuit. FIG. 4 shows an enlarged waveform of a signal related to guard band detection in the luminance signal Y, and FIG. 5 shows an enlarged waveform of a signal related to guard band detection in the chroma signal C.

FIG. 14 is an enlarged view of a portion of the video record location of FIG. In FIG. 14, θ1 is 4.68111 degrees, θ2 is 4.6 degrees, and θ3 is 1
At 5.3311, the distance between the center of the track Y track of the luminance signal Y and the center of the track C track of the chroma signal C is 165.7 μm. The forward direction of the luminance signal Y will be described. During normal reproduction, the head h moves from the position a to the position b at an angle of θ2.
On the other hand, at the time of reproduction by the search operation, the head h
Moves from position a to position c. By the way, x shown in the figure
Is 45.7 sin (15.3331 degrees).
8 μm. Since the track length is 114.98mm ,
The projected length of the track length in the horizontal direction is 114.98.
It becomes 114.60 mm by cos (4.68 degrees).
This 114.60mm is converted to 312.5H (PAL or SEC
Divided by the number of H in one track in the AM system, etc.), 1
The length obtained by projecting the H length in the horizontal direction is approximately 366.7 μm. Then, the ratio of x to the length of the 1H length projected in the horizontal direction is approximately 11.9%. Therefore, as shown in FIG. 15, at the time of reproduction in the forward direction by the search operation of the luminance signal Y, the GH signal (FIG. 15A) arrives earlier than the position in the case of normal reproduction, so that the fall is performed.
The write phase reference signal (see FIG. 15)
B) is reliably reset, and a normal image can be output from seven lines of the GH signal. However, as shown in FIG. 16, at the time of reproduction in the reverse direction by the search operation of the luminance signal Y, since the GH signal (FIG. 16A) arrives later than the position in the case of normal reproduction, it falls.
Write phase reference signal with reference to edge (FIG. 16B)
Resets later than the falling edge of the GH signal
Therefore, a normal image can not be output for the seven lines. As described above, since the luminance signal Y and the chroma signal C are recorded on the tape while changing the azimuth angle,
At the time of reproduction by the chroma signal search operation, the phenomenon opposite to that described with reference to FIGS. Therefore, some processing must be performed on the guard band signal by the luminance signal Y and the chroma signal C.

FIG. 6 illustrates an example of the mix guard band signal generation circuit 20 described in FIG. 2 for performing such processing. In FIG. 6, 26 is an input terminal to which a first guard band signal is supplied, 22 is an input terminal to which a second guard band signal is supplied, 23 is an input terminal to which a third guard band signal is supplied, and 24 is a third input terminal. This is an input terminal to which a 4-guard band signal is supplied. The first, second, third, and fourth guard band signals from these input terminals 26, 22, 23, and 24 are supplied to a guard band detection circuit 25.
Respectively. The guard band detection circuit 25 performs an AND operation on all of the first, second, third, and fourth guard band signals supplied via the input terminals 26, 22, 23, and 24, respectively, and uses this as a mixed guard band signal. 1
H (one horizontal period) extension circuit 2 9 and a switch 27
To one of the fixed contacts 27a. The 1H extension circuit 29, the average period detecting signal supplied to the clock input terminal, a mix guard band signal from the guard band detecting circuit 25 1H (one horizontal period) min stretching, the 1H partial stretching mix guard band < A signal is supplied to the other fixed contact 27b of the switch 27. When a signal from a switch 32 to be described later is at a low level “0”, the movable contact 27 c of the switch 27 is connected to one fixed contact 27 of the switch 27.
a, and when the signal from the switch 32 is at a high level "1", the movable contact 27c of the switch 27 is connected to the other fixed contact 27b, and one and the other fixed contacts 27a and 27b of the switch 27 are connected. Mi was stretched mix guard band signal and 1H fraction are respectively supplied to the
Switch any one of the guard band signals
Is supplied to one of the fixed contacts 41a. Reference numeral 34 denotes an input terminal to which a guard sync signal from the gate circuit 7 is supplied.
Is an input terminal to which a dropout signal from the dropout stretch circuit 6 is supplied. These input terminals 3
The guard sync signal and the dropout signal are supplied to the high-speed guard band detection circuit 36 via 4 and 35, respectively. This high-speed guard band detection circuit 36 is connected to an input terminal 34.
And give an average drop-out period detecting signal based on the guard sync signal and dropout signal from 35, to form a guard band signal based on the average drop-out period detecting signal, one of the guard band signal of the switch 39 The fixed contacts 39a and 2H (two horizontal periods) are supplied to a stretching circuit 38, respectively. This 2H stretching circuit 3
8, a guard band signal faster guard band detecting circuit 36 on the basis of the guard sync signal supplied through the input terminal 37 from the gate circuit 7 2H (two horizontal periods) min stretching, the stretched guard band signal Is supplied to the other fixed contact 39b of the switch 39. When a signal from a switch 32 to be described later is at a low level "0", the movable contact 39c of the switch 39 is connected to one fixed contact 39a of the switch 39, and the signal from the switch 32 is at a high level. When "1", the movable contact 39c of the switch 39 is connected to the other fixed contact 39.
b, and supplies one of the guard band signal supplied to one and the other fixed contacts 39a and 39b of the switch 39 and the guard band signal expanded by 2H to the other fixed contact 41b of the switch 41. I do.

Reference numeral 30 denotes an input terminal to which a high level "1" is supplied when the tape traveling direction is reverse, that is, reverse, and a low level "0" is supplied when the tape traveling direction is forward, that is, forward. Is an input terminal to which a low level "0" is supplied when the tape traveling direction is reverse, that is, reverse, and a high level "1" is supplied when the tape traveling direction is forward, that is, forward. This is a terminal to which a control signal that is at a high level “1” at the time and low at a chroma signal at “0” is input. A switch 32 has one fixed contact 32a of the switch 32.
Is supplied with a signal of the high level "1" or low level "0" indicating the above-described reverse or forward, and the other fixed contact 32b of the switch 32 has the high level "1" or the low level indicating the above-described forward or reverse. A signal of level “0” is supplied. When the control signal from the input terminal 33 is at a high level "1", the switch 32 connects the movable contact 32c of the switch 32 to one fixed contact 32a, and the control signal from the input terminal 33 is at a low level. When "0", this switch 32
Is connected to the other fixed contact 32b.
The signal from the switch 32 is supplied as a control signal to the switches 27 and 39, respectively. Switch 4 1
Indicates that the control signal from the input terminal 40 is high level "1" (±
When the speed is 30 times or less), the movable contact 41c of the switch 41 is connected to one fixed contact 41a of the switch 41, and the control signal from the input terminal 40 is low level "0".
In the case of (more than ± 30 times speed), the movable contact 41c of the switch 41 is connected to the other fixed contact 41b of the switch 41, and the signal from the switch 27 or the switch 39 is supplied to the output terminal 42.

Now, this mix guard band signal generation circuit 20 is used in the luminance signal processing system,
In addition, when the speed is ± 30 times or less, a high-level “1” signal is supplied to the input terminal 30 and a low-level “0” signal is supplied to the input terminal 31. Then, the control signal from the input terminal 33 becomes high level “1”, and the switch 32
Is connected to the fixed contact 32a of the switch 32. As a result, a high-level "1" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to the switch 2
7 is connected to the other fixed contact 27b, and the movable contact 39c of the switch 39 is connected to the other fixed contact 3 of the switch 39.
9b. Thus, 1H via switch 27
The 1H stretched mix guard band signal from the stretcher 29 is applied to one fixed contact 41 of the switch 41.
a, and the guard band signal expanded by 2H from the 2H expansion circuit 38 is supplied to the switch 4.
1 and is supplied to the other fixed contact 41b. On the other hand, the movable contact 41c of the switch 41 is connected to one of the fixed contacts 41a by a control signal of a high level "1" from the input terminal 40.
Connected to. The output terminal 42 is supplied with the 1H stretched mix guard band signal from the 1H stretch circuit 29.

Next, this mix guard band signal generation circuit 20 is used in a luminance signal processing system, and when the speed is less than ± 30 times speed in the forward direction, a signal of low level “0” is supplied to the input terminal 30. , An input terminal 31 is supplied with a high-level "1" signal. And input terminal 3
3 is at a high level "1", and the movable contact 32c of the switch 32 is connected to the fixed contact 32a of the switch 32.
Connected to. As a result, a low-level "0" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to one fixed contact 27a of the switch 27.
Nine movable contacts 39c are connected to one fixed contact 39a of the switch 39. Thus, the mixed guard band signal from the guard band detection circuit 25 is supplied to one fixed contact 41a of the switch 41 via the switch 27, and the guard band signal from the high speed guard band detection circuit 36 is supplied to the other of the switch 41. Fixed contact 41b
Supplied to On the other hand, the movable contact 41 of the switch 41
“c” is connected to one fixed contact 41 a by a control signal of a high level “1” from the input terminal 40. The output terminal 42 is supplied with a mixed guard band signal from the guard band detection circuit 25.

Next, this mix guard band signal generation circuit 20 is used in a luminance signal processing system,
When the speed is ± 30 times or more, a high-level “1” signal is supplied to the input terminal 30 and a low-level “0” signal is supplied to the input terminal 31. Then, the control signal from the input terminal 33 becomes high level “1”, and the switch 32
Is connected to the fixed contact 32a of the switch 32. As a result, a high-level "1" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to the switch 2
7 is connected to the other fixed contact 27b, and the movable contact 39c of the switch 39 is connected to the other fixed contact 3 of the switch 39.
9b. Thus, 1H via switch 27
The 1H stretched mix guard band signal from the stretcher 29 is applied to one fixed contact 41 of the switch 41.
a, and the guard band signal expanded by 2H from the 2H expansion circuit 38 is supplied to the switch 4.
1 and is supplied to the other fixed contact 41b. On the other hand, the movable contact 41c of the switch 41 is connected to the other fixed contact 41b by a low level “0” control signal from the input terminal 40.
Connected to. The output terminal 42 is supplied with the guard band signal expanded by 2H from the 2H expansion circuit 38.

Next, this mix guard band signal generation circuit 20 is used in a luminance signal processing system, and when the speed is more than ± 30 times speed in the forward direction, a signal of low level “0” is supplied to the input terminal 30. , An input terminal 31 is supplied with a high-level "1" signal. And the input terminal 33
The control signal becomes high level "1", and the movable contact 32c of the switch 32 becomes the fixed contact 32a of the switch 32.
Connected to. As a result, a low-level "0" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to one fixed contact 27a of the switch 27.
Nine movable contacts 39c are connected to one fixed contact 39a of the switch 39. Thus, the mixed guard band signal from the guard band detection circuit 25 is supplied to one fixed contact 41a of the switch 41 via the switch 27, and the guard band signal from the high speed guard band detection circuit 36 is supplied to the other of the switch 41. Fixed contact 41b
Supplied to On the other hand, the movable contact 41 of the switch 41
“c” is connected to the other fixed contact 41 b by a low-level “0” control signal from the input terminal 40. The output terminal 42 is supplied with a guard band signal from the high-speed guard band detection circuit 36.

Next, when this mix guard band signal generating circuit 20 is used in a chroma signal processing system and the reverse direction and the speed is ± 30 times or less, a high-level “1” signal is supplied to the input terminal 30. Then, a signal of low level “0” is supplied to the input terminal 31. Then, the control signal from the input terminal 33 becomes low level “0”, and the movable contact 32 c of the switch 32 becomes the fixed contact 32 of the switch 32.
b. As a result, a low-level "0" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to one fixed contact 27a of the switch 27. 39c is connected to one fixed contact 39a of the switch 39. Thus, the mixed guard band signal from the guard band detection circuit 25 is supplied to one fixed contact 41a of the switch 41 via the switch 27, and the guard band signal from the high speed guard band detection circuit 36 is supplied to the other of the switch 41. Fixed contact 41
b. On the other hand, the movable contact 4 of the switch 41
1c is connected to one fixed contact 41a by a control signal of high level "1" from the input terminal 40. The output terminal 42 is supplied with a mixed guard band signal from the guard band detection circuit 25.

Next, this mix guard band signal generation circuit 20 is used in a chroma signal processing system, and when the speed is less than ± 30 times the speed in the forward direction, a low-level “0” signal is supplied to the input terminal 30. , An input terminal 31 is supplied with a high-level "1" signal. And input terminal 3
3 becomes low level "0", and the movable contact 32c of the switch 32 becomes the fixed contact 32b of the switch 32.
Connected to. As a result, a high-level "1" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to the other fixed contact 27b of the switch 27.
Nine movable contacts 39c are connected to the other fixed contact 39b of the switch 39. Thus, the 1H-stretched mix guard band signal from the 1H-stretching circuit via the switch 27 is applied to one fixed contact 41 of the switch 41.
a, and the guard band signal expanded by 2H from the 2H expansion circuit 38 is supplied to the switch 4.
1 and is supplied to the other fixed contact 41b. On the other hand, the movable contact 41c of the switch 41 is connected to one of the fixed contacts 41a by a control signal of a high level "1" from the input terminal 40.
Connected to. The output terminal 42 is supplied with the 1H stretched mix guard band signal from the 1H stretch circuit 29.

Next, when this mix guard band signal generating circuit 20 is used in a chroma signal processing system and the reverse direction and the speed is ± 30 times or more, a high level “1” signal is supplied to the input terminal 30. Then, a signal of low level “0” is supplied to the input terminal 31. Then, the control signal from the input terminal 33 becomes low level “0”, and the movable contact 32 c of the switch 32 becomes the fixed contact 32 of the switch 32.
b. As a result, a low-level "0" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to one fixed contact 27a of the switch 27. 39c is connected to one fixed contact 39a of the switch 39. Thus, the mixed guard band signal from the guard band detection circuit 25 is supplied to one fixed contact 41a of the switch 41 via the switch 27, and the guard band signal from the high speed guard band detection circuit 36 is supplied to the other of the switch 41. Fixed contact 41
b. On the other hand, the movable contact 4 of the switch 41
1c is connected to the other fixed contact 41b by a low-level "0" control signal from the input terminal 40. The output terminal 42 is supplied with a guard band signal from the high-speed guard band detection circuit 36.

Next, this mix guard band signal generation circuit 20 is used in a chroma signal processing system, and when the speed is in the forward direction and ± 30 times or more, a signal of low level “0” is supplied to the input terminal 30. , An input terminal 31 is supplied with a high-level "1" signal. And input terminal 3
3 becomes low level "0", and the movable contact 32c of the switch 32 becomes the fixed contact 32b of the switch 32.
Connected to. As a result, a high-level "1" signal from the switch 32 is supplied to the switches 27 and 39, respectively, and the movable contact 27c of the switch 27 is connected to the other fixed contact 27b of the switch 27.
Nine movable contacts 39c are connected to the other fixed contact 39b of the switch 39. Thus, the 1H-stretched mix guard band signal from the 1H-stretching circuit via the switch 27 is applied to one fixed contact 41 of the switch 41.
a, and the guard band signal expanded by 2H from the 2H expansion circuit 38 is supplied to the switch 4.
1 and is supplied to the other fixed contact 41b. On the other hand, the movable contact 41c of the switch 41 is connected to the other fixed contact 41b by a low level “0” control signal from the input terminal 40.
Connected to. The output terminal 42 is supplied with the guard band signal expanded by 2H from the 2H expansion circuit 38. When the mixed guard band signal generating circuit 20 is used in the chroma signal processing system, particularly when the projected image is monochrome at ± 30 × speed or more, the control by the video signal reproducing device supplied to the input terminal 40 is performed. The signal remains at high level "1".

As is apparent from the above description, when the mix guard band signal generation circuit 20 is used in a chroma signal processing system of a time axis correction device of a video signal reproducing device, which will be described later, a 1H stretching circuit is used during forward operation. 29, the mix guard band signal is extended by 1H and output, so that the minimum gray replacement can be performed, thereby obtaining an extremely high quality image. Also, when the mix guard band signal generation circuit 20 is used in a luminance signal processing system of a time axis correction device of a video signal reproducing device described later, 1H is used during a reverse operation.
Since the mix guard band signal is expanded by 1H and output by the expansion circuit 29, the minimum gray replacement can be performed, thereby obtaining an extremely high quality image.

In the above-mentioned mix guard band signal generating circuit 20, as described above, when the speed is less than ± 30 times, the gate signal is supplied by the control signal from the input terminal 40.
Circuit, average period detection circuit, average pulse width detection circuit, phase detection
Based on the first to fourth guard band signals obtained from the output circuit.
Mixed guard band signal or 1H
So as to output the mixed guard band signal enlargement came, average + 30-times speed (forward) or more when based on the guard sync signal and dropout signal dropout
Give out periodic detection signal, to output a high-speed guard band signal formed on the basis of the average drop-out period detecting signal, the guard band signal faster guard band detecting circuit 36 when the -30-times speed (reverse) or Is output as a guard band signal by extending 2H based on the guard sync signal. As shown in FIG. 7, the average horizontal period of the reproduced horizontal synchronizing signal (FIG. 7A) is observed when the speed is higher than -30.times. (Reverse), so that the high-speed guard band detection circuit 36 described in FIG. From the average period detection signal (FIG. 7E). However, as described above, eight lines are not reset for the write reference due to the azimuth. Therefore, the guard band signal (FIG. 7D) from the high-speed guard band detection circuit 36 is expanded by 2H, and FIG.
A guard band signal as shown in FIG. Also, +
At 30 times speed or higher, the high-speed guard band detection circuit 3
In FIG. 6, an average period detection signal (FIG. 7C) can be obtained from the seven lines of the reproduced horizontal synchronization signal shown in FIG. 7A, and a guard band signal as shown in FIG. 7D is formed based on the average period detection signal. can do.

As described above, when the speed is higher than +30 times (forward), an average dropout period detection signal is obtained based on the guard sync signal and the dropout signal.
A high- speed guard band signal formed based on the dropout period detection signal is output. When the speed is higher than -30 times (reverse), the guard band signal from the high-speed guard band detection circuit 36 is used as a guard sync signal. Since a signal expanded by 2H is output as a guard band signal based on this, an extremely high-quality image can be obtained even at the time of high-speed reproduction of 30 times or more in either the forward or reverse direction.

Next, an example in which the synchronization signal detection circuit described with reference to FIGS. 2 and 6 is applied to a time axis correction device of a video signal reproducing device will be described with reference to FIG. In FIG. 1, reference numeral 50 denotes an input terminal to which a reproduced video signal (luminance-based video signal) from a video signal reproducing apparatus main body (not shown) is supplied, and a reproduced video signal from the input terminal 50 (hereinafter simply referred to as video data). Described) is an A / D converter (analog-digital converter) 52 and a sync separation / P
It is supplied to an LL (phase locked loop) circuit 51. The A / D converter 52 converts a luminance signal from the input terminal 50 into, for example, an 8-bit digital signal using a write clock from the synchronization separation / PLL circuit 51, and supplies the digital signal to a luminance signal processing circuit 53. I do. On the other hand, the sync separation / PLL circuit 51 has an input terminal 50.
The synchronous signal is separated from the luminance signal, the phase is locked, a write clock and a write phase reference signal are generated, a reproduced synchronous signal is supplied to the synchronous signal detecting circuit 53, and the write clock is converted to an A / D converter. 5
2. It is supplied to the cancel circuit 54, the insert circuit 55, the memory controller 56 and the memory 57, respectively.

The synchronization signal detection circuit 53 already described with reference to FIGS. 2 and 6 supplies the synchronization separation / PLL circuit 51 with the guard sync signal and the phase detection signal, and
5 is supplied with a dropout signal and a guard band signal, and a judgment circuit 59 described later is supplied with a guard band signal. The cancel circuit 54 includes a sync separation / PLL circuit 51
Based on the write clock, drop-out processing and pre-processing for gray replacement are performed. That is, A-
If the upper 7 bits of the 8-bit video data (luminance signal system reproduced video data signal) from the D converter 52 are all "0", this data is set to "00000010" and supplied to the insert circuit 55 as data. . The insert circuit 55 converts the video data whose data is “00000010” from the video data from the cancel circuit 54 into a drop-out signal (corresponding to drop-out processing) or a guard band signal (for gray replacement processing) from the synchronization signal detection circuit 53. Signal), ie, data of “00000000” corresponding to dropout processing (hereinafter simply referred to as dropout processing data), or 8 bits least significant bit Is "1", that is, "00000000" corresponding to the gray replacement process.
1 "(hereinafter simply referred to as gray replacement processing data). The insert circuit 55 supplies the converted dropout processing data, gray replacement processing data, or ordinary video data which is not converted to the memory 57. I do.

The memory controller 56 has a sync separation / PL
A write control signal is generated based on a write clock and a write phase reference signal from the L circuit 51, and the write control signal is supplied to the memory 57. On the other hand, the memory controller 56 includes a read reference signal generation circuit 61
A read control signal is generated based on the read clock and the read phase reference signal, and the read control signal is supplied to the memory 57. Therefore, writing of video data (dropout processing data or gray replacement processing data) to the memory 57 is performed by the memory controller 5.
6 according to the write control signal from the sync separation / PLL
Reading of video data (including dropout processing data and gray replacement processing data) from the memory 57 is performed in accordance with a reading control signal from the memory controller 56 in accordance with a writing clock from the circuit 51.
It performed using a read Heading clock than the reference signal generating circuit 61 read. The read reference signal generation circuit 61 supplies a read clock to the detection circuit 58 and the output processing circuit 60 in addition to the memory controller 56, the memory 57, and the synchronization signal detection circuit 53.

The video data (including dropout processing data and gray replacement processing data) read from the memory 57 is supplied to the detection circuit 58. The detection circuit 58 detects whether the video data from the memory 57 is normal video data, dropout processing data, or gray replacement processing data based on a read clock from the read reference signal generation circuit 61. If the video data is the dropout processing data, a dropout detection signal is supplied to the determination circuit 59. If the video data from the memory 57 is the gray replacement processing data, a gray replacement detection signal is supplied to the determination circuit 59. The video data from the memory 57 is supplied to the output processing circuit 60. The judgment circuit 59 includes a dropout detection signal or a gray replacement detection signal from the detection circuit 58, a control signal supplied from the video / tape recorder main unit via the input terminal 73 and indicating a reproduction speed of less than ± 3 times, and the memory controller 56. Based on the read control signal, the timing of the dropout processing, the timing of the gray replacement processing, and the detection of the first line of the guard band are performed, and the output detection circuit 60 outputs the dropout processing timing signal or the gray replacement timing. Providing a processing signal. The output processing circuit 60 performs dropout processing or gray replacement processing of video data from the detection circuit 58 based on the dropout processing timing signal or gray replacement timing processing signal from the determination circuit 59, and outputs the video data subjected to these processings. Is supplied to the addition circuit 70 via the DA converter 62.

As described above, in the beta cam system, the write phase reference in the search operation is, for example, as shown in FIG. 8 due to the azimuth in the tape format. Here, for example, if there is a dropout (FIG. 8C) from line 2 to line 6 of the horizontal synchronizing signal of the reproduced video signal, the reproduced horizontal synchronizing signal cannot be taken from line 3 to line 6. At this time, the guard band portion corresponds to three to six lines of the reproduced horizontal synchronization signal as shown in FIG. 8D. Therefore,
As shown as tx in FIG. 8B, writing is not performed for a predetermined amount. At this time, after the video signal is read out from the memory 57 and the video signal is projected on the screen of a monitor or the like without performing the gray processing on the read side, as shown in FIG. Are projected as previously written data tx. If the memory 57 is a so-called line memory, the data tx moves on the screen of the monitor, resulting in an image that is very hard to see visually. The numbers 1 to 8 on the left are shown in FIG.
Correspond to the numerals 1 to 8 described in the reproduction horizontal synchronization signal. Further, d is a dropout portion, which corresponds to the dropout portion shown in FIG. 8C, and g is a guard band portion, which corresponds to the guard band portion shown in FIG. 8D.

However, the decision circuit 59 described above uses the timing of the read control signal generated by the memory controller 56 based on the read phase reference signal {read reference horizontal synchronization signal (FIG. 10A)} as shown in FIG. 10B. A guard band portion as shown in FIG. 10C is detected for the output, and a dropout processing timing signal and a gray replacement processing timing signal are supplied to the output processing circuit 60 in response to the detection. Therefore, if a video signal is projected on a monitor or the like after dropout processing or gray replacement processing is performed on the read side after reading from the memory 57, writing is not performed as shown in FIG. The predetermined portion is not displayed as the previously written data tx, but is displayed as the gray-substituted portion tb. The numbers 1 to 8 shown on the left correspond to the numbers 1 to 8 shown in the reference horizontal synchronization signal of FIG. 10A, respectively. Further, ta is a dropout processing part, corresponding to the dropout processing part ta of the dropout part shown in FIG. 10B and the guard band part shown in FIG. 10C, and tb is a gray replacement processing part shown in FIG. 10C. This corresponds to the gray replacement processing part tb of the guard band part. Also, the judgment circuit 59
, When the guard band portion is two or more horizontal periods of the reference horizontal synchronizing signal, as shown in FIG. 1 0 C, in the first one horizontal period one horizontal period before the video data of the guard band portion, A dropout processing timing signal is supplied to the output processing circuit so as to perform a so-called dropout processing. Then, as shown in FIGS. 3K, 7D, and F, the output circuit 60 performs a gray replacement process (shown as tb in each figure) on the video signal portion corresponding to the guard band portion of the guard band signal, and further outputs the guard band. When the portion extends over two horizontal periods, a portion of the video signal corresponding to the first one horizontal period of the guard band portion is called video data one horizontal period earlier, so-called dropout processing (referred to as ta in each drawing). Shown). Therefore,
As shown in FIG. 11, a dropout processing part t of the dropout part shown in FIG.
a and the dropout processing part ta of the guard band part shown in FIG. 10C is subjected to the dropout processing and is displayed (shown as ta in the figure), and the gray processing part tb of the guard band part shown in FIG. It is projected.

Further, the judgment circuit 59 has an input terminal 73
When a signal indicating a search operation at a speed of ± 3 times or less becomes active, the above-described so-called line dropout processing is not performed. The reason for this is that, when performing a so-called line drop-out process when the guard band portion is equal to or more than two horizontal periods as described above during a low-speed search of ± 3 × speed or less, because of the low-speed search, it is displayed on the screen of a monitor or the like. This is because the projected image has four lines of the same video data including ODD and EVEN, which makes it easy to visually discriminate and makes the image hard to see.

Next, the circuit of the chroma signal system will be described. The input terminal 64 is supplied with a reproduced video signal (a chroma video signal). The reproduced video signal (hereinafter simply referred to as video data) is supplied to a chroma signal processing circuit 65 via an input terminal 64. Since the chroma signal processing circuit 65 has substantially the same circuit configuration as the luminance signal processing circuit 72, illustration and detailed description thereof are omitted. The video data (color difference signals RY and BY) signal-processed by the chroma signal processing circuit 65 are converted into analog signals by DA converters 66 and 67, respectively, and supplied to an encoder circuit 68. The encoder circuit 68 reads the subcarriers supplied from the reference subcarrier signal generation circuit 61 by the reference subcarrier signal generation circuit 69.
A reference subcarrier signal obtained based on a clock (for example, 4FSC) and a chroma signal based on the color difference signals RY and BY are obtained, and the chroma signal is supplied to the adding circuit 70. The addition circuit 70 adds the luminance signal from the DA converter 62 and the chroma signal from the encoder circuit 68 to obtain a color video signal, and supplies this color video signal to the output terminal 71. The color video signal is supplied to, for example, a monitor connected to the video signal reproducing device via an output circuit or the like of the video signal reproducing device main body, and is projected as an extremely high quality image on the monitor screen of the monitor. . still,
It is assumed that the above-described chroma signal processing circuit 65 also performs the same guard band detection, dropout processing, and gray replacement processing as the luminance signal processing circuit 72.

As is clear from the above, in this example,
When the mix guard band signal generating circuit 20 is used in the chroma signal processing system of the time axis correction device of the video signal reproducing device, the 1H stretching circuit 29 extends the mix guard band signal by 1 H during the forward operation and outputs the signal. As a result, the minimum gray replacement can be performed, thereby obtaining an extremely high quality image. When the mix guard band signal generation circuit 20 is used in the luminance signal processing system of the time axis correction device of the video signal reproducing device, the 1H stretching circuit 29 stretches the mix guard band signal by 1 H during the reverse operation and outputs the result. As a result, the minimum gray replacement can be performed, so that an extremely high quality image can be obtained.

Further, to obtain an average drop-out period detecting signal + 30-times speed (forward) or more when based on the guard sync signal and dropout signal, the average drop
A high-speed guard band signal formed based on the pull-out period detection signal is output. When the speed is higher than -30 times (reverse), the guard band signal from the high-speed guard band detection circuit 36 is expanded by 2H based on the guard sync signal. Since the signal is output as a guard band signal, the signal is output in either forward or reverse direction.
An extremely high quality image can be obtained even at the time of high-speed reproduction at double speed or higher. Further, in the synchronization signal detection circuit 53, since the guard band detection is performed based on the read clock and the read phase reference signal, even if the previous data remains in the memory 57, the corresponding portion of the data is replaced with gray. The image can be processed without causing so-called image disorder in the projected image. Also, when the guard band portion is equal to or more than two horizontal periods of the reference horizontal synchronization signal, the output is performed so as to perform a so-called dropout process with video data one horizontal period before the first horizontal period of the guard band portion. Since the dropout processing timing signal is supplied to the processing circuit, the minimum gray replacement processing can be performed to make the projected image easy to view.

The present invention is not limited to the above-described embodiment, but may take various other configurations without departing from the gist of the present invention.

[0044]

According to the present invention described above, the detection signal generating means generates the horizontal cycle detection signal for detecting the horizontal cycle of the reproduction synchronization signal based on the reference signal. When the detection period of the detection signal generated based on the horizontal period detection signal and the reproduction synchronization signal extends over at least two horizontal periods, the compensating means sets the reproduction period corresponding to one horizontal period at the beginning of the detection period of the detection signal. The video signal portion is interpolated with the information before the reproduced video signal corresponding to one horizontal cycle at the beginning of the detection period of the detection signal.
And the start of the detection period of this detection signal other than one horizontal cycle
Is replaced with gray . For example, when applied to a time axis correction device of a video signal playback device, the minimum gray replacement can be performed during a search operation, and so-called gray replacement can be performed. There is an advantage that an extremely high quality image can be displayed without causing image disturbance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment in which a signal processing circuit of a video signal reproducing apparatus according to the present invention is applied to a time axis correction apparatus.

FIG. 2 is a block diagram showing a main part of an embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 3 is a timing chart for explaining one embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 4 is a timing chart for explaining one embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 5 is a timing chart for explaining one embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 6 is a block diagram showing a main part of an embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 7 is a timing chart for explaining one embodiment of a signal processing circuit of the video signal reproducing apparatus of the present invention.

FIG. 8 is an explanatory diagram showing a timing at the time of writing.

FIG. 9 is an explanatory diagram showing an image projection state.

FIG. 10 is a timing chart showing dropout processing and gray replacement processing after reading.

FIG. 11 is an explanatory diagram showing an image projection state.

FIG. 12 is an explanatory diagram showing a video record location of the beta cam system.

FIG. 13 is a timing chart showing a conventional guard band detection and gray replacement.

FIG. 14 is an enlarged view of a part of the video record location of the beta cam system.

FIG. 15 is an explanatory diagram showing image bending at the time of a forward operation.

FIG. 16 is an explanatory diagram illustrating image bending during a reverse operation.

[Explanation of symbols]

 4 Divider circuit 5 Horizontal cycle count circuit 6 Dropout stretch circuit 7 Gate circuit 8 Timing generator 9 Average horizontal cycle data latch circuit 10 Average horizontal cycle detection circuit 11 Average cycle detection signal generation circuit 12 Gate circuit 13 Average cycle detection circuit 17 Average Pulse width detection circuit 18 Phase detection circuit 20 Mix guard band signal generation circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/91-5/956

Claims (1)

(57) [Claims] 1. A horizontal cycle detection signal generating means for generating a horizontal cycle detection signal for detecting a horizontal cycle of a reproduction synchronization signal based on a reference signal, and a horizontal cycle detection signal from the horizontal cycle detection signal generating means. beginning of the reproduction detection signal generating means for generating a detection signal based on the synchronization signal, when the detection period of the detection signal from the detection signal generating means over at least two horizontal periods, the detection period of the detection signal A portion of the reproduced video signal corresponding to one horizontal cycle is interpolated with information before the reproduced video signal corresponding to one horizontal cycle at the beginning of the detection period of the detection signal, and the detected signal is detected.
Reproduction corresponding to other than one horizontal period at the beginning of the signal detection period
A signal processing circuit for a video signal reproducing apparatus, comprising: a compensating unit that replaces a video signal portion with gray .