JP2890425B2 - Video signal playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal reproducing apparatus suitable for use in a helical scan VTR, particularly a so-called azimuth recording / reproducing VTR.

[Summary of the Invention] The present invention provides a playback color video signal in a variable speed playback mode.
In a video signal playback apparatus that passes through a JOG circuit and inserts a pseudo vertical synchronization signal into the playback color video signal, the playback color video signal is JOG in a specific mode of the variable playback mode.
By inserting a pseudo vertical synchronizing signal into the reproduced color video signal without passing through the circuit, an image quality equivalent to that of the normal reproduction mode can be obtained even in the specific mode of the variable speed reproduction mode, and the reproduction screen is displayed at the time of the mode transition. The vertical synchronization is not disturbed.

[Conventional technology]

Conventionally, in a rotary-ed VTR, for example, an azimuth recording / reproducing VTR, an operation mode called a JOG mode is provided in the rotary head-type VTR as a function of searching for a reproduction start point from the recording tape when reproducing the recording tape. ing.

In the JOG mode, when the recording tape is mounted on this VTR and in the playback mode, this recording tape is played back in the first motion (cue) or reverse motion (review), and the playback start point is roughly searched. Subsequently, the recording tape is played back in the slow motion playback state and the still playback state to find a desired playback start point, and subsequently, the recording locus on this recording tape before and after the found point at the same tape transfer speed as at the time of recording. Is reproduced, and it is possible to confirm whether or not the found point is a desired reproduction start point.

The problem with such a JOG mode is that the recording tape is played back with the recording tape being transported at a different tape transport speed or at a different tape transport direction than during recording. This JOG is a state in which the reproduction locus of the reproduction head by the reproduction head does not exactly match, and the vertical synchronization signal recording section on the recording tape cannot be reproduced, or the reproduction can be performed only at a signal level that cannot be used as a vertical synchronization signal. This occurs during the mode, and it is necessary to perform time axis correction so that the horizontal period signal period of the signal reproduced from the recording tape becomes the same as that at the time of recording.

In the case where the recording signal system is the PAL system, in addition to this correction, a correction such as a change of a burst signal is required.

Therefore, in the conventional JOG mode, as a countermeasure against the case where the vertical synchronizing signal in the reproduced signal is absent or the signal level of the vertical synchronizing signal is too low to be used as the vertical synchronizing signal, the patent application publication 62 As described in FIG. 2 and its description in Japanese Patent No. 32869, in particular, a pseudo-vertical signal is provided at a time point earlier than a reproduction vertical synchronizing signal section originally included in a signal reproduced from a reproduction recording tape. A sync signal is added, and even when the vertical sync signal in the reproduced signal is absent or when the signal level of the vertical sync signal is too low to be used as a vertical sync signal, the vertical sync signal is used to perform vertical sync. In this way, it is possible to reproduce a reproduced video without disturbing the image on the monitor device.

If the horizontal cycle of the horizontal cycle signal is different from that during recording, a time axis correction circuit of the CCD system is provided to correct this time axis error.
62-32869, JP-A-58-27486, etc.).

[Problems to be solved by the invention]

By the way, what is further required as a function in the JOG mode is that a recording tape is run in a fast motion (cue) playback or a reverse motion (review) playback state to roughly search for a desired playback start point, and to perform slow motion playback and still motion playback. After playing the recording tape in the playback state and searching for the desired playback start point, the operation until the playback of the recording trajectory on the recording tape before and after this searched point at the same tape transfer speed at the time of recording is continuously performed. The purpose is to keep the reproduction quality as good as possible when reproducing the recording trajectory on the recording tape before and after the point searched for at the same tape transport speed as at the time of recording.

However, a problem in keeping the reproduced image quality as good as possible is the time axis correction circuit provided in the JOG circuit.

That is, the reproduction signal input to the time axis correction circuit is sampled and quantized, and then input to the time axis correction circuit to perform the time axis correction. At this time, the sampling frequency is about 3Fc (10Z8 MHz). Therefore, it is necessary to insert a high-frequency cutoff frequency filter before the time axis correction circuit to limit the high frequency band of the reproduced signal to the Nyquist frequency or lower, and to minimize the number of quantization bits. Therefore, there is a problem that the image quality of the reproduced signal that has passed through the time axis correction circuit deteriorates.

In particular, in the case of the PAL system, the JOG circuit performs the replacement of the burst signal of the reproduction signal in addition to the time axis correction, but if the reproduction signal is subject to jitter fluctuation, the replacement burst does not include the jitter fluctuation. The phase error correlated with the jitter generated between the signal and the color signal in the reproduced signal causes a problem that the image quality is further deteriorated by appearing as grayscale noise of the color on the monitor reproduced image in addition to the deterioration of the image quality. As a solution to this problem, when transitioning from a state such as slow motion playback in the JOG mode to a specific mode state in which the tape is played at the same tape transfer speed as at the time of recording, for example, at the time of this transition It is conceivable that the signal reproduced from the tape is directly supplied to the video monitor device to switch to a normal reproduction state in which the signal is reproduced as a video.

However, in the case where the switching is performed in this manner, from the state in which the signal to which the pseudo vertical synchronization signal is added at a time point earlier than the vertical synchronization signal section is supplied to the video monitor device and reproduced as a video, A signal that does not include the pseudo vertical synchronizing signal is supplied to the video monitor device and is switched to a state in which it is reproduced as a video.

As a result, at the time of this switching, the period of the vertical synchronization signal of the signal supplied to the video monitor device jumps from the pseudo vertical synchronization signal period to the vertical synchronization signal period of the signal reproduced from the reproduction recording tape. At the time of jumping to the normal V, the video of the playback screen being reproduced by the video monitor device jumps in the vertical direction or the vertical synchronization of this video is temporarily lost depending on the pull-in speed of the vertical synchronization circuit of the video monitor device. A phenomenon called jitter occurs on the reproduced screen, and there is a problem that the image becomes very unsightly.

The present invention has been made in view of the above points, and in a specific mode of the variable speed reproduction mode such as the x1 mode, a high quality reproduced image exactly the same as the original normal reproduction mode is obtained, and the reproduction screen is displayed at the time of the mode transition. It is intended to provide a video signal reproducing apparatus capable of preventing vertical synchronization of the video signal from being disturbed.

[Means for solving the problem]

According to the present invention, a reproduced color video signal reproduced in the variable speed reproduction mode is supplied to a JOG circuit (7) for correction, and a corrected color video signal obtained from the JOG circuit is supplied to a pseudo vertical synchronization signal insertion circuit (10). In a video signal reproducing apparatus in which a pseudo vertical synchronizing signal is added to a corrected reproduced color video signal, it is detected that the video signal reproducing apparatus is in a variable speed reproduction mode and in a specific reproduction mode of the variable speed reproduction mode. Detecting means (14) for supplying the reproduced color video signal to the JOG circuit (7) to obtain a corrected color video signal and for obtaining the reproduced color video signal without passing through the JOG circuit (7). Switching means for switching (8)
And detecting means (14) when the detecting means (14) detects that the video signal reproducing apparatus is in the variable speed reproducing mode and in the specific reproducing mode of the variable speed reproducing mode.
Controls the switching means (8) to obtain a corrected color video signal from the JOG circuit (7), and switches to a state in which the reproduced color video signal is obtained. (10) to insert a pseudo vertical synchronizing signal into the reproduced color video signal.

[Action]

Specific mode of variable speed playback mode (JOG mode)
In the 1 mode, the reproduced color video signal is not passed through the JOG circuit (7). As a result, high image quality similar to that of the conventional normal reproduction mode can be obtained even in the × 1 mode. Also, since the state of the specific mode such as the x1 mode is one of the variable speed reproduction modes, in this variable speed reproduction mode, the mode shifts from the × 1 mode to another variable speed reproduction mode, or conversely, the other variable speed reproduction mode. To x1 mode.
By inserting the pseudo vertical synchronizing signal into the reproduced color video signal in a specific mode such as the × 1 mode without passing through the JOG circuit (7), the reproduced color video signal is changed from the × 1 mode. Even when shifting to another variable-speed playback mode or when shifting to the × 1 mode from another variable-speed playback mode, the video of the playback screen being played back by the video monitor device is prevented from being disturbed.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. A reproduced video signal reproduced from the magnetic tape (1) through the magnetic head (2) is supplied to a luminance signal processing circuit (4) and a chrominance signal processing circuit (5) through an RF amplifier (3). The signal and the reduced converted carrier color signal are separated.

The luminance signal processing circuit (4) demodulates the luminance FM signal into a luminance signal, and the chrominance signal processing circuit (5) frequency-converts the reduced conversion carrier chrominance signal to 3.58 MHz for the NTSC system and 4.43 MHz for the PAL system. To the carrier color signal. These signals are added by an adder (6) and output as a reproduced color video signal.

(7) is a JOG circuit, (8) and (9) are switches, (1)
0) is a pseudo vertical synchronizing signal insertion circuit, and (11) is an output terminal. Further, (12) is an input terminal to which a high-level JOG mode signal is always applied, and (13) is a low-level signal in a mode other than the × 1 mode, and a high-level signal is applied in a mode other than the × 1 mode. As an input terminal, a low level signal is obtained as a switching signal at the output side of the AND circuit (14) in the × 1 mode, and a high level signal in modes other than the × 1 mode. This switching signal is supplied to a switch (8), and the switch (8) is controlled to be connected to the contact a when the switching signal is at a low level and to be connected to the contact b when the switching signal is at a high level.

Reference numeral (15) denotes an input terminal to which a mode switching signal is supplied. In the normal reproduction mode, the switch (9) is connected to the contact a, and in the JOG mode, the switch (9) is connected to the contact b. You. (16) is an input terminal to which a pseudo vertical synchronization signal is supplied, and this pseudo vertical synchronization signal is supplied to a pseudo vertical synchronization signal insertion circuit (10).

In the normal reproduction mode, the reproduced color video signal obtained at the output side of the adder (6) passes through the contact (a) of the switches (8) and (9) and the output terminal (11).
Is output to

On the other hand, in the x1 mode, the switch (8) is set to the contact a side,
Since the switch (9) is connected to the contact b, the reproduced color video signal obtained at the output of the adder (6) passes through the contact a of the switch (8) without passing through the JOG circuit (7). The signal is supplied to the pseudo vertical synchronization signal insertion circuit (10) through the contact b side of the switch (9), where the pseudo vertical synchronization signal from the input terminal (16) is inserted and output to the output terminal (11). . Therefore, in the case of this × 1 mode, the output terminal (11)
Can obtain the same color video signal as in the original normal reproduction mode, so that the image quality does not deteriorate. In addition, since the pseudo vertical synchronizing signal to be inserted in the JOG mode is also inserted, the vertical synchronization of the reproduction screen is not disturbed.

Also, in the JOG mode other than the x1 mode, since the switches (8) and (9) are both connected to the contact b side, the reproduced color video signal obtained at the output side of the adder (6) is JO
The pseudo vertical synchronizing signal insertion circuit (10) is supplied to the G circuit (7), receives the predetermined signal processing as described above, passes through the contact b of the switch (8), and further passes through the contact b of the switch (9). ), Where the pseudo vertical synchronizing signal is inserted and output to the output terminal (11).

As described above, in the present embodiment, in the × 1 mode of the JOG mode, the reproduced color video signal does not pass through the JOG circuit (7) and the pseudo vertical synchronization signal is inserted, so that the image quality is the same as the original normal reproduction mode. Image quality can be obtained, and V-jitter does not occur due to disturbance of vertical synchronization in the reproduction screen. In addition, this method is a television system (NTSC, PAL, etc.)
Regardless of, the NTSC method can be applied to VTRs passing through the JOG circuit, and the PAL method can be applied to almost all VTRs.

〔The invention's effect〕

As described above, according to the present invention, in the specific mode of the variable-speed reproduction mode, the reproduced color video signal is not passed through the JOG circuit and the pseudo vertical synchronization signal is inserted into the reproduced color video signal. Even in the mode, an image quality equivalent to the original normal reproduction mode can be obtained, and the vertical synchronization of the reproduction screen is not disturbed at the time of the mode transition.

[Brief description of the drawings]

The accompanying drawings are circuit diagrams showing an embodiment of the present invention. (7) is a JOG circuit, (8) is a switch, (10) is a pseudo vertical synchronizing signal insertion circuit, and (14) is an AND circuit.

Claims (1)

(57) [Claims] 1. A reproduction color video signal reproduced in a variable speed reproduction mode is supplied to a JOG circuit for correction, and a corrected color video signal obtained from the JOG circuit is supplied to a pseudo vertical synchronizing signal insertion circuit to provide the corrected reproduction color signal. A video signal reproducing apparatus configured to add a pseudo vertical synchronizing signal to a video signal, wherein a detecting means for detecting that the video signal reproducing apparatus is in the variable speed reproduction mode and in a specific reproduction mode of the variable speed reproduction mode; Switching means for switching between a state in which the reproduced color video signal is supplied to the JOG circuit to obtain the corrected color video signal and a state in which the reproduced color video signal is obtained without passing through the JOG circuit, and the detecting means When it is detected that the video signal playback device is in the variable speed playback mode and in the specific playback mode of the variable speed playback mode, A step controls the switching means to switch the state in which the corrected color video signal is obtained from the JOG circuit to the state in which the reproduced color video signal is obtained without passing through the JOG circuit, and the reproduced color video signal obtained by the pseudo A video signal reproducing apparatus which supplies a reproduced vertical video signal to a reproduced color video signal in a pseudo vertical synchronizing signal insertion circuit, the video signal being supplied to a vertical synchronizing signal insertion circuit.