JPS60253004A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To shift the titled device to a recording state from a recording pause state, etc. without passing through a rewinding or reproducing state, and to eliminate a time loss by making a level transition of a recording head switching signal exist in an accelerating period of a capstan motor, when shifting the device to a recording state from a stop state, and also starting a supply of a recording current to a recording head at the same time as the level transition. CONSTITUTION:A device which satisfies a condition that a time required for a recording tape speed as a capstan motor, which reaches zero from a prescribed value is smaller than a period corresponding to about one frame of a recording video signal is used. When shifting the device to a recording state from a recording pause state, a head recording current is turned on by a high level transition timing from a low level of an SWP signal (a head switching signal made from a rotary phase signal of a head drum) after the acceleration has been started. In that case, a head to which the recording current is supplied is controlled so as to become a head opposite to a head recorded immediately before shifting to a recording pause state. In this way, a file phase of a recording video signal before and after an editing point has a continuity.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a recording/reproducing apparatus, and more particularly to a helical scan type magnetic tape recording/reproducing apparatus.

BACKGROUND ART Such a recording and reproducing device is called a so-called VTR (video tape recorder), and this VTR is capable of insert recording, assemble editing, etc. (so-called continuous recording. In this case, the recording state Recording standby (pause)
This can be done by rewinding the magnetic tape to a certain extent in response to a recording pause command, and then rewinding the magnetic tape to the recording state when transitioning to the recording state.
A common method is to start recording after applying the capstan servo while reproducing the TI signal.

In this method, in addition to the time loss of rewinding the tape and applying the capstan servo, errors at the editing point are unavoidable.

On the other hand, recently so-called 8wllVT using 8wll VT
R is proposed (・ruρ・, this V 'I' R is C
Instead of the TL method, it uses a so-called 4-frequency Birono] tracking method. Therefore, when performing the so-called splice recording described above, in this four-frequency pilot tracking system, the signal system needs to be put into the playback state and the tracking servo is applied, and then shifted to the trap recording state. Therefore, there is a drawback that there is a time loss until a stable state is achieved due to switching of the recording/reproducing amplifier system, switching of the signal system, etc.

Not only during the transition from the recording pause state to the recording state,
A problem similar to the above occurs also when transitioning from a still playback state, slow playback state, etc. to a recording state.

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording and reproducing apparatus that can accurately perform splice recording when the recording head drum is rotating and the capstan motor is in a stopped state when transitioning from a stopped state to a recording state.

The recording/reproducing apparatus according to the present invention can reduce the recording tape speed, the time required to reach a specified value from zero, or one of the recorded video signals.
A capstan motor with sufficient characteristics to satisfy a condition shorter than a frame equivalent period, and a recording head that switches during the accelerating period of the capstan motor when the drum is rotating and the capstan motor is in a stopped state to the recording state. It is characterized by comprising means for controlling the acceleration start timing of the capstor/motor so that there is a level transition of the signal, and means for starting supply of recording current to the recording head simultaneously with the level transition of the recording head switching signal (・Ru.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention, in which a capstan motor 1 is rotationally controlled by current control from a drive power source 2, and this drive current is controlled by a current switching circuit 3. . The switching operation of the current switching circuit 3 is performed by the output of a controller 4 using a microprocessor such as a microconbeater.
C) Command signal and recording standby (FtECPAUSB) Head switching signal (switching signal and S
WP), etc., and generates a switching operation command for the current switching circuit 3 and an on/off control command for the head recording current according to a predetermined procedure.

FIG. 2 is a time chart illustrating the operation of the apparatus shown in FIG. 1, in the case where there is a recording pause command at time t1 in the recording state, and there is a recording command at time t3 in this recording pause state. , is a diagram showing the relationship between the SWP signal phase, the tape speed, and the on/off timing of the recording current to the recording head.

In order to minimize the bending of the recording track at the editing point during splicing recording, the capstan motor (recording tape) must have characteristic curves that are symmetrical to each other for the deceleration state in which it reaches zero from the specified speed and the opposite acceleration state. It is necessary to control it so that it forms a straight line. In addition, to prevent card bands (gaps between tracks) from occurring at editing points, it is necessary to limit the tape feed amount to within 1 track pitch in °C during the acceleration/deceleration period, including the constant speed period of the recording tape. Is required. Furthermore, in order to prevent the recording track width at the editing point from becoming too narrow, the amount of tape feed during the acceleration/deceleration period, including the constant speed period, must be equal to or greater than the track pinch. Therefore, it is desirable that the tape feed amount during the acceleration/deceleration period including the constant speed period be one trunk pitch.

For the sake of simplicity, it is assumed that the acceleration and deceleration when starting and stopping the capstan are both constant acceleration and deceleration, and the absolute values are equal to °C. Let ts be the time required for acceleration and deceleration at this time, and t be the constant speed period required to obtain the tape feed amount of one track pitch in combination with the acceleration and deceleration periods.
Let it be N. Also, the specified tape speed during steady running is I.

, the amount of tape fed during the constant speed period and the acceleration/deceleration period is I・
, one field (l/2 frame) time is τ2. ,
−.

As mentioned above, by assuming that the tape feed amount during the acceleration/deceleration period including the constant speed period is one track pitch, the following equation is established.

The reference point t=O is set at the time of the level transition of the swp signal (the transition timing from a high level to a low level in FIG. 2) following the recording pause command time t1. From equation (1), the following equation can be obtained.

tN - τ - (1/2) ts - (21 From equation (2), it is necessary to use a capstan motor with sufficient characteristics to satisfy the condition that ts < 2 (one frame period). Become.

Furthermore, in order to perform continuous recording, it is necessary to cut off the recording current to the head during the deceleration period (ts) rather than cutting off the recording current to the head before starting deceleration. Also, if the recording current is cut off in the middle of a track, the F (high frequency) signal will be cut off and the track will be cut off in the middle, so it is necessary to cut off the recording current only after recording one track. be. For these reasons, the recording current is controlled to be cut off at the timing of the level transition of the SWP signal after the shift to deceleration. Then, the tape will be fed until the recording current is cut off. N is - υ0(τ-'s/2) + (3/s)'sv
.

=υ. (τ-ts/8) ・(3) Here, use a beam to connect the tracks completely without bending. Whether it is necessary that N = L, this means (
1) From equation (3), it means that ts=o, so as a result, track curvature will inevitably occur and is unavoidable. Therefore, in order to reduce trunk bending,
Is it necessary to make ts as small as possible? ts is several ms
is the limit. As a practically possible value, for example, t
If s=τ, then from equation (3) LON ”υ.(τ−'
/8) −(7/8)ν. τ=(7/8)L・(
4), 12.5'%) The rack will enter the recording pause state after it bends. This bending behavior is shown in the dotted line trunk 5 in FIG.

Next, when moving from this recording pause state to the recording state,
Contrary to the above, the head recording current is turned on at the transition timing from the low level to the high level of the SWP signal after the start of acceleration. At this time, the head to which the recording current is supplied is controlled to be the opposite head to the head that recorded immediately before entering the recording pause state. By doing so, the field phase of the recorded video signal before and after the editing point has continuity.

Furthermore, in the case of the so-called four-frequency tracking method, it goes without saying that control is performed to maintain the continuity of the tracking pilot signal. In other words, for each field of the four pilot frequencies f1 to f4, f, → f2 → f3 → f,
For example, if a pilot signal with a frequency of f is recorded immediately before changing to the recording pause state, the pilot signal of f2 is recorded next time when changing from the recording pause state to the recording state. The information is recorded in the above order.

In this case, the track will turn in the opposite direction to that when the transition from the previous recording to the recording pause occurs, resulting in a track 6 indicated by a dotted line in FIG. 3. In this case as well, to eliminate the guard band, the width should be 125 cm wider than the track pitch. For example, if the trunk pitch is 20 pJrL, if the head width is wider than 22.571 m, the card band will not occur. , the maximum possible l(F
Signal drop is 201oy (7/8) --1,2da
It is a level that has almost no effect.

The example described above is for the period equivalent to ts-τ (] field, which is approximately 16.7 ms), and the values are shown for the start timing of deceleration and acceleration, the on/off timing of the recording current, and the head width. As can be seen from this example, due to the characteristics of the capstan motor, ts
By knowing this and its variations, the acceleration/deceleration timing and head width can be calculated by the above procedure, and therefore the controller 4
If you program the acceleration/deceleration timing of the capstan motor and the on/off timing of the recording current in advance so that you can command them, you can seamlessly record splices without having to go through tape rewinding, playback, etc. It becomes possible.

Even if a capstan motor with ts-2τ, which is the worst condition, is used, the RF signal level drop will be 20
toy (37'4) -2.5dB and Dw(
Head width) = 1.25TP (Track pitch) =
25111n, guard bands do not occur and continuous recording is possible without any practical problems.

It should be noted that the present invention is not limited to the transition from the recording pause state to the recording state, but is similarly applicable to the transition from the capstan stopped state to the recording state in a rotary drum rotation state such as a still playback or slow playback state.

Effects of the Invention As described above, according to the present invention, it is possible to shift from a recording pause state to a recording state without rewinding or checking the playback state, so there is no time loss at all, and it is possible to record a good 41+ summer pre-recording. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a time chart explaining the operation of the blocks in FIG. 1, and FIG. 3 is a diagram showing the recording track at an editing point. Explanation of symbols for main parts 1 - Capstan motor 2 Current switching circuit 4 - Controller 5, 6 Record) Rank applicant Pioneer Co., Ltd. agent Patent attorney Rattan Motohiko

Claims (1)

[Claims] a capstan motor with sufficient characteristics to satisfy the condition that the time required for the recording tape speed to reach the specified value from zero or a period equivalent to approximately one frame of the recording video signal;
When the recording head is in the drum rotation state and the capstan motor is in a stopped state and transitions from the capstan motor stopped state to the recording state, the acceleration start timing of the capstan motor is set so that a level transition of the recording head switching signal exists during the acceleration period of the capstan motor. A recording/reproducing apparatus characterized in that it includes a controlling means and a means for starting supply of a recording current to the recording head at the same time as the level transition of the recording head switching signal.