JPH01227248A - Frame control device for magnetic recording device - Google Patents

Abstract

PURPOSE:To prevent the turbulence of an image at signal reproducing time by actuating a frame servo function during a pauseperiod, controlling a rotary head corresponding to the field of an input signal and holding the corresponding relation even after the pose release. CONSTITUTION:When a normal video signal is input, a frame pulse signal (b) is fed to a dividing circuit 18 via an AND gate 17 to actuate a frame servo function, in case of a switch 16 being connected to 16b and of a pause state by an auto mode. When recording is performed thereafter by releasing the pause state, a reset pulse (b) is fed to the circuit 18 via the gate 17 and the servo function is released. However the signal (d) of 30Hz that a vertical synchronizing signal (c) is divided from the circuit 18 is output and the corresponding relation of 1st and 2nd fields in the state of servo being exerted during the pause state and the rotary head of channels 1, 2 is held. No image turbulent at reproducing time is thus caused even if the normal signal is changed over to the signal excepting the normal during the servo.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a frame control device for a magnetic recording device, and more particularly to a frame control device for a magnetic recording device having a frame servo function and a pause function.

BACKGROUND OF THE INVENTION Traditionally, high-end professional VTRs have a frame servo function that maintains the correspondence between the odd field (first field) and even field (second field) of an input video signal and two rotating heads. something is known. When continuing recording after a recording has been interrupted, or when performing insert editing, the correspondence between the first and second fields and the two rotating heads may be reversed, resulting in continuous fields of the same type on the tape. If the recorded portion is recorded in this way, skew will occur when the recorded portion is played back. The frame servo function maintains the correspondence between the fields and the magnetic head, and prevents the same type of field from being continuously recorded on the tape, thereby eliminating this knee.

However, if this frame servo function is working all the time, frame detection may occur, for example: ■ When there is a dropout or a lot of noise around the vertical synchronization signal, ■ When the same type of field comes in consecutively for some reason, etc. As a result, the servo function will not work properly. For this reason, when something recorded in this manner is played back, there are problems in that screen shakes, tracking errors, etc. occur.

Therefore, in order to solve this problem, the present applicant proposed an apparatus, the block diagram of which is shown in FIG. 3, in Japanese Patent Laid-Open No. 60-226054 (Japanese Patent Application No. 59-83437).

In the figure, during playback or in E, E, mode, switch 4 is connected to terminals P, B, and 6 from oscillator 12.
0)-1z signal passes through the 1/2 frequency divider circuit 5 and becomes 30
The frequency is divided into Hz and supplied to the phase comparator circuit 6. Also 2
A drum pulse (see FIG. 2(E)'J) detected by a pickup head 8 from a rotating drum 7, which has two rotating heads (not shown) provided at 180 degree intervals and is driven by a motor 11, is generated by a waveform shaping circuit 9. (The output signal is shown in Figure 2 (
The signal is supplied to the phase comparator circuit 10 via F).

The phase comparison circuit 6 compares the phases of the two input signals as described above, outputs an error signal according to the phase difference, and supplies it to the phase compensation circuit 10, which controls the motor. By doing so, the rotation of the drum 7 and the output signal of the 1/2 frequency dividing circuit 5 are synchronized.

On the other hand, during recording, switch 4 is connected to the ROC terminal.

The input signal received from the terminal 1 is separated into a synchronization signal by the synchronization separation circuit 2, and this synchronization signal is supplied to the field discrimination circuit 13 and also to the vertical synchronization separation circuit 3.
Also supplied. The vertical synchronization separation circuit 3 further separates only the 60 Hz vertical synchronization signal from the synchronization signal, and supplies these to the field discrimination circuit 13 and the 1/2 frequency divider circuit 5.

The field discrimination circuit 13 generates a frame pulse of 30)-IZ based on the equalization pulse of the synchronization signal and the vertical synchronization signal, and supplies it to the frame servo control circuit 15. This frame pulse is a signal that identifies the first field and the second field, and is, for example, a 30 Hz signal that does not generate a pulse during the second field period and generates a pulse only during the first field period.

The frame servo control circuit 15 shapes the waveform of the room pulse only for a predetermined period after the start of recording and supplies it to the 1/2 frequency divider circuit 5. That is, the vertical synchronization separation circuit 3
The vertical synchronizing signal of 30H7 supplied to the 1/2 frequency dividing circuit 5 is outputted as a 30 Hz signal synchronized with this frame pulse and supplied to the phase comparator circuit 6. During this time, the frame servo function operates, and the frame servo is applied to the rotation of the rotary drum 7 and the vertical synchronization signal, thereby maintaining the correspondence between the first field, the second field, and the two rotary heads.

Thereafter, after the predetermined period has elapsed, the frame servo control circuit 15 cuts off the frame servo pulse. However, because the frame servo is applied, even if the frame servo function stops working, the first and second
The correspondence between the field and the two magnetic heads does not change.

Problems to be Solved by the Invention However, in the apparatus shown in FIG. 3, the NTSC standard signal (hereinafter referred to as a regular signal or regular video signal) used for television broadcasting is transmitted while the frame servo function is operating after the start of recording. If a signal other than the above (for example, a video special playback signal or a computer video signal, etc.) comes in, the field discrimination circuit 13
A malfunction occurs in the frame detection by the system, which disrupts the frame servo, and when a signal recorded in this way is played back, the video becomes distorted for several seconds.

Also, if you use the device shown in Figure 3 when, for example, recording multiple types of video signals that are not synchronized while switching them to create a single video work, the drum servo will lock after switching the signals. There was a problem that the image was unstable for several seconds until the image was released.

The present invention has been made in view of the above points, and it is possible to record without disturbing the reproduced video even if a signal other than the regular signal is received immediately after recording starts or immediately after switching the video signal. Frame system t2fl of magnetic recording device
'The purpose is to provide an IA location.

Means for Solving the Problems The present invention provides a magnetic recording system having a frame servo function for applying frame servo using frame pulses obtained by determining odd or even fields of a video signal, and at least a pause function during recording. In the frame control device of the device, there is a pause detection means that detects that the device is stopped and outputs a signal indicating that the device is paused, and a frame control device that detects that the device is paused and outputs a signal indicating that the device is paused, and a frame control device that detects that the device is stopped during the pause period according to the output signal of the pause detection device. The frame servo control means operates the frame servo function and stops the operation of the frame servo function after the temporary stop is released.

During the active pause period, the frame servo function operates to control the rotary head to rotate in accordance with each field determined from the input video signal. Even if the temporary stop is canceled from this state, the correspondence between each field and the rotary head is maintained.

In addition, even if the recording state changes to a pause state, and during this pause period the television broadcast channel is changed and the recording state returns again, the frame servo-like function will stop operating when the pause is canceled. When a signal recorded in this way is played back, the video will not be distorted due to the connection of frames here and there.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a timing chart of the apparatus shown in FIG.

Components in FIG. 1 that are the same as those in FIG. 3 are designated by the same reference numerals.1. The explanation will be omitted.

In Figure 1, if the input video signal coming into terminal 1 is a regular signal, the odd field (first field)
and an even field (second field) are repeated alternately, and one frame consists of one set of the first field and the second field.

The sync separation circuit 2 separates the sync signal a shown in FIG. 2(A) from the normal signal and supplies it to the vertical sync separation circuit 3 and the field discrimination circuit 13. , the vertical synchronization separation circuit 3 separates the 60Hz vertical synchronization signal C shown in FIG. 2(C) from the synchronization signal a, and the field discrimination circuit 13 separates the synchronization signal
The frame pulse b shown in FIG. 2(B) is generated only during the period of the first field by identifying whether it is the first field or the second field from the equalization pulse (equalization pulse immediately before the vertical synchronization signal). This field discrimination circuit 13 can accurately discriminate between two fields in the case of a regular signal, but it may malfunction when the signal is of a different format from the regular signal, such as a special playback video signal or a personal computer signal. The generated frame pulse b becomes a high level ()I) or a low level (shi,) regardless of the field.

18 is a frequency divider circuit that divides the frequency of the input signal into half and outputs it. This frequency divider circuit 18 outputs a signal from the Q terminal regardless of the input signal of the T@i terminal while the reset (R) terminal is H, and outputs the signal input to the TE terminal when the reset terminal is L. The level of the Q output is changed from H to H and from L to H in synchronization with the rise. The vertical synchronization signal C is supplied from the vertical synchronization separation circuit 3 to the lower terminal of this frequency dividing circuit 18, and the switch 16 is connected to the reset terminal.
When the frame pulse b1 switch 16 is connected to the Q element, the output of the AND gate 17 is supplied when the frame pulse b1 switch 16 is connected to the 16b element.

During recording, switch 19 is set to 19a, switch 16 is set to 16
a and a regular video signal is input to input terminal 1, a 60Hz vertical synchronizing signal is input to the lower terminal of frequency divider circuit 18, and this signal is shown in FIG. 2(D). The signal d of 30 Hz is outputted from the Q terminal of the frequency dividing circuit 18.

This signal jqd of 30H2 is supplied to the phase comparator circuit 6,
This becomes the reference signal for the frame servo, and as in the conventional device shown in Fig. 3, the rotary head of channel 1 is placed in the first field.
The rotary heads of channel 2 correspond to the second fields, respectively, and are subjected to frame servo.

If the input video signal input to terminal 1 here is a signal other than a regular signal, the field discrimination port i13 will not be able to discriminate the field, and if the frame pulse remains, for example, H, the frequency dividing circuit 18 is always in a reset state and the output from the Q terminal remains at L. Therefore, at this time, phase comparison cannot be performed in the phase comparator circuit 6, and frame servo is not applied.

Furthermore, when the switch 16 is connected to 16c and the frame servo is off, the reset terminal of the frequency dividing circuit 18 becomes L, and the probability that the heads of channels 1 and 2 synchronize with the frame even in the case of a normal signal and the frame The probabilities of not being synchronized are both 1/2, and the first field is not always recorded by the rotary head of channel 1, and the second field is not always recorded by the rotary head of channel 2.

On the other hand, when the switch 16 is connected to 16b and the auto mode is set, and the recording is in a pause state, one input terminal of the AND gate 17 is sent from the mechanical control circuit 20. An H signal is supplied to.

When a regular video signal enters terminal 1 in this state, AN
The output of the D gate 17 is equal to the frame pulse b input to the other input terminal, and this signal is supplied to the reset terminal of the frequency divider circuit 18 via the switch 16, so that the frame servo function operates as described above. I will do it.

When the frame servo-applied pause state is released and the recording state is entered, the signal supplied from the mechanical control circuit 20 to the AND gate 17 becomes L. As a result, the output of the AND gate 17 is supplied to the reset terminal of the frequency dividing circuit 18 regardless of the level of the reset pulse b, so that the frame servo function is canceled. However, from the Q output terminal of the frequency dividing circuit 18, a 30H7 signal d, which is the frequency-divided vertical synchronizing signal C, is continuously output, and the first and second signals are The correspondence between the fields and the rotary heads of channels 1 and 2 is maintained and recorded.

Therefore, when the switch 16 is connected to 16b and is in the auto mode and is in the pause state, for example, when switching the input video signals from two cameras, or when changing the channel of the television signal. It takes a few seconds for the frame servo to work when switching, but
When frame servo is applied, Bose is canceled and recording is performed, the part where recording was temporarily interrupted due to a pause will be recorded as a continuous frame, so even if this part is played back, the image will not be distorted.

Furthermore, if the switch 6 is connected to 6a and the frame servo is always applied, and a signal other than the normal signal is input as an input video signal, the frame servo function will work even though a normal frame pulse b cannot be obtained. Therefore, the video may be distorted, but if the switch 16 is connected to 16b and set to auto mode, the frame servo function is already canceled in the recording state, so the input video signal may be a regular signal. The servo will not be disturbed even if the signal is switched from the normal signal to a signal other than the normal signal.

During playback, switch 19 is connected to 19b and oscillator 21
By performing phase comparison using a 30 Hz signal as a reference signal, the rotating drum 7 is servoed.

Effects of the Invention As described above, according to the present invention, even when changing the channel of a television signal during a pause period or switching and recording multiple unsynchronized camera inputs, the same operation can be performed during the pause period. By releasing the pause after the frame servo has been activated, frame continuity can be maintained, and even if the video signal from a computer, etc. is switched to a non-regular signal during recording, the Since the frame servo function is stopped, the screen has the advantage that even if the recorded signal is played back, the screen will not be distorted.

[Brief Description of the Drawings] Fig. 1 is a block diagram of one embodiment of the present invention, and Fig. 2 is a block diagram of an embodiment of the present invention.
A timing diagram to explain the operation of the device shown in the figure,
FIG. 3 is a block diagram of a conventional device. 2... Sync separation circuit, 3... Vertical sync separation circuit, 6
... Phase comparison circuit, 7... Rotating drum, 9... Waveform shaping circuit, 10... Phase compensation circuit, 13... Field discrimination circuit, 15... Frame servo control circuit, 17...・AND gate, 18... frequency dividing circuit, 20... mechanical control circuit. Patent Applicant Victor Company of Japan Co., Ltd. No. 1 Cause Figure 2 (G) 1 cHll C)+2 o-+1 No. 3
figure

Claims (1)

[Scope of Claims] A frame control device for a magnetic recording device having a frame servo function for applying frame servo using a frame pulse obtained by determining odd or even fields of a video signal, and at least a pause function during recording. , a pause detection means that detects that the frame is paused and outputs a signal indicating that the frame is paused; and a frame servo function that activates the frame servo function during the pause period according to the output signal of the pause detection means. 1. A frame servo control device for a magnetic recording device, comprising frame servo control means for operating the frame servo function and stopping the operation of the frame servo function after the temporary stop is released.