JP3363523B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus (hereinafter, referred to as a VTR), and more particularly to a tracking adjusting means. 2. Description of the Related Art Rotating two-head helical scan type V
With respect to TR, it is necessary to accurately trace the recorded video track, and therefore, at the time of recording, a signal related to the rotation phase of the rotary head, for example, 分 of a vertical synchronization signal separated from a video signal to be recorded. The signal synchronized with the peripheral output is recorded as a control signal.
Tracking servo is applied so as to lock at a certain phase with a head switching pulse as rotation phase information of the cylinder so that the reproduced control signal and the rotation phase of the rotary head have a predetermined phase relationship. As a result, accurate tracking is always performed as long as the phase relationship between the track of the video signal recorded on the magnetic tape and the control signal is kept constant. However, when the recorded VTR differs from the reproduced VTR, the phase of the head switching pulse and the reproduction control signal cannot be uniquely determined. A tracking adjustment circuit for delaying a pulse is provided, and the time constant is made variable by a manual operation using a tracking volume so that optimum tracking can be achieved. In recent years, an auto-tracking technique for automatically searching for an optimum tracking point by monitoring an envelope signal reproduced by a rotary head has been established (Japanese Patent Laid-Open No. 61-110).
358). Note that self-recording / playback is adjusted at the time of shipment from a factory so that optimal tracking is performed with a preset tracking center value. In the above-mentioned VTR, when a magnetic tape recorded by another VTR is inserted and recording such as splicing is performed, the VTR has a previously adjusted delay amount (timing data). ), The control signal is recorded. When this magnetic tape is reproduced, tracking is disturbed because the phase relationship between the control signal and the head switching pulse is deviated by setting the splicing position to be different. Therefore, in the manual operation type VTR, the tracking volume must be variably adjusted when tracking is disturbed. In the automatic tracking type VTR, when the tracking is disturbed, it is not possible to reproduce the envelope signal. A circuit that constantly monitors is required. Further, there is a disadvantage that the reproduced image is also disturbed from the time the tracking is disturbed until the optimum tracking is achieved. Therefore, according to the present invention, during reproduction, tracking is controlled so that the reproduced control signal and the rotational phase of the rotary head have the best phase relationship by the tracking adjusting means. In the magnetic recording and reproducing apparatus, insertion detecting means for detecting that a magnetic tape has been inserted into the magnetic recording and reproducing apparatus, ejection detecting means for detecting that a magnetic tape has been ejected, and the insertion detecting means A forced reproducing means for forcibly bringing the magnetic tape into a reproducing state when the insertion of the magnetic tape is detected, and tracking data adjusted by the tracking adjusting means when the magnetic tape is brought into the reproducing state by the forced reproducing means. Means for holding until the ejection of the magnetic tape is detected, and when recording, the magnetic tape is held by the holding means. Recording means for sequentially recording the control signal on the magnetic tape while adjusting the recording timing of the control signal based on the tracking data so that the recording cycle of the control signal becomes substantially the same. According to the above arrangement, when performing splicing recording on a magnetic tape recorded by another VTR or the like, the recording cycle of the control signal is substantially the same as the cycle before recording. , The tracking disturbance during reproduction does not occur. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment, and FIGS. 2 and 3 are flowcharts showing the operation of the embodiment. In this embodiment, the present invention is applied to a VHS type video tape recorder (VTR). As described in the background art, a VTR generally records a control signal (30 Hz) in the longitudinal direction of the tape during recording in order to perform tracking servo. At the time of reproduction, the phase of the reproduced control signal is compared with the head switching pulse (or the reference signal which is the reference of the rotational phase of the rotary head) which is the rotational phase information of the cylinder, and the tracking servo is controlled by controlling the phase of the tape running. Be executed. Then, the amount of delay of the reproduction control signal (or head switching pulse) is adjusted so that noise is not generated on the reproduction screen during reproduction. In this embodiment, a VTR using an auto-tracking system for automatically performing the above-mentioned tracking adjustment is provided.
Will be described. In FIG. 1, reference numerals 1 and 2 denote rotary heads,
Reference numeral 20 denotes a head switching (R) for head switching control.
FSW) pulse input terminal, 4 is a head switching circuit, 5 is an envelope detection circuit, 6 is a microcomputer that performs tracking control or control signal recording timing control, 7 is a switch that detects insertion or ejection of a magnetic tape, 8 is a control head, 9, 1
Reference numerals 4 and 15 are switches that can be switched by recording or reproduction. Reference numerals 10 and 11 denote a reproduction / recording amplifier, 12 a tracking adjustment circuit for delaying a reproduction control signal,
13 is a timing adjustment circuit for delaying a control signal to be recorded, 16 is a capstan motor, 17 is a frequency generator (FG) that generates an FG pulse according to the rotation of the capstan motor 16, and 18 is an FG pulse from the FG in advance. A speed control circuit 19 compares the error signal with a predetermined speed reference signal and feeds back an error signal to the capstan motor 16. A tracking control circuit 12 applies a control signal (or head switching pulse) obtained from the control head 8 during reproduction to the tracking control circuit 12. The delayed signal is compared with a head switching pulse (or a control signal), an error signal is fed back to the capstan motor 16, and at the time of recording, an FG pulse from the FG and a vertical synchronizing signal separated from a recording video signal described later are recorded. 1/2 divided Compared bets, a phase control circuit for feeding back the error signal to the capstan motor 16. Reference numeral 21 denotes an input terminal to which a recording video signal is input; 22, a vertical synchronization separation circuit for separating a vertical synchronization signal from the recording video signal;
A frequency dividing circuit for dividing the frequency by 2 and a mode control circuit 24 for controlling modes such as a reproduction mode and a recording mode. Next, the operation at the time of reproduction will be described with reference to the flowchart of FIG. At the time of reproduction, as shown in FIG.
14 and 15 are connected to the reproduction (P) side, respectively. Then, the detection switch 7 detects whether or not a magnetic tape has been inserted into the VTR (step S1).
Is set to a predetermined center value (step S2). This is because the case where the inserted magnetic tape is recorded by the present VTR (self-recording / reproducing) is considered. When the mode control circuit 24 is forcibly set to the reproduction mode (step S3), the outputs of the rotary heads 1 and 2 are converted into one system signal by the head switching circuit 4 and input to the detection circuit 5. You. The detection circuit 5 extracts the envelope of the reproduction output. The microcomputer 6 uses the output of the detection circuit 5 as the input of the A / D input. The microcomputer 6 has an A / D converter, converts an analog value supplied to the A / D input into a digital value, and takes in the digital value at a predetermined timing. Further, the microcomputer 6 is supplied with an RFSW pulse for timing control. Then, in the microcomputer 6, the RF
The rising of the SW pulse (square wave) is detected (step S
4) A / D conversion and input of the output of the detection circuit 5 (step S5), and this is repeated at a predetermined sampling interval.
The sampling interval is, for example, 1 ms (step S9). This sampling is performed for one field period (step S8). All the sample values in one field period are added (integrated) to obtain a value N corresponding to the current envelope. At this time, when it is determined that there is no detection output (step S6), step S6 is performed.
Proceed to 14 to end the reproduction mode. Then, it is checked whether this value N is the maximum value (step S10). This can be known, for example, by examining the past N to see if it has fallen from the ascending process. If it is not the maximum value, the tracking data is changed by a predetermined value (step S11). This is instructed from the microcomputer 6 to the tracking adjustment circuit 12. If the maximum value is reached, the tracking data at this time is stored in the memory in the microcomputer 6 (step S12), and the tracking adjustment operation is terminated (step S13), and the reproduction operation is also terminated (step S14). The tracking adjustment operation also operates when normal playback is performed on a VTR,
In this case, only steps S3 to S13 are performed. Next, the operation at the time of recording will be described with reference to the flowchart of FIG. First, the detection switch 7 detects whether or not the magnetic tape in the above-described reproduction mode has been ejected (step S21). If the magnetic tape has not been ejected, a recording button for performing a splicing photograph ( (Not shown), the microcomputer 6 reads out the tracking data stored in the memory (step S22), and based on the tracking data, sets the timing so as to be the same as the control signal recording cycle before the splicing shooting. The adjustment circuit 13 is adjusted (Step S24). Therefore,
The tracking data and the timing adjustment data are substantially the same data. This is instructed from the microcomputer 6 to the timing adjustment circuit 13. As a result, the 垂直 vertical synchronizing signal from the frequency dividing circuit 23 is delayed for a predetermined time by the timing adjusting circuit 13 and is recorded as a control signal on the magnetic tape by the control head 8 via the recording amplifier 11 and the switch 9. . Although not shown, the 1/2 vertical synchronizing signal is also used as a reference signal for the phase control circuit of the rotary head. Therefore, since the cycle of the control signal is continuous, the cycle of the control signal is not disturbed, and tracking disturbance does not occur. The recording state is continued until a stop button (not shown) is operated (step S25). Also,
When an operation other than the recording button is performed, another operation is set based on the operation of the button (step S26). On the other hand, when the ejection of the magnetic tape is detected by the switch 7, the timing adjustment circuit 13 is set to a preset initial value (step S23), and the processing is terminated. Here, the timing adjustment circuit 13 is set to the preset initial value so that self-recording and reproduction can be performed when the newly inserted magnetic tape is a virgin tape. In the present invention, the reproducing mode is forcibly set after the magnetic tape is inserted. However, when the recording button is operated, the magnetic tape is rewound for a certain period to set the reproducing mode.
The recording mode may be set after the tracking data is obtained. According to the present invention, even when spliced recording is performed on a magnetic tape recorded by another VTR or the like, control is performed such that the recording cycle of the control signal is the same as that before recording. Therefore, the cycle of the control signal is not disturbed even when the splicing recording is performed. Also, there is no disturbance in the reproduced image at the joint shooting position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing an embodiment of the present invention. FIG. 2 is a flowchart showing a reproducing operation of the embodiment. FIG. 3 is a flowchart illustrating a recording operation according to the embodiment. [Description of Signs] 5 Envelope detection circuit 6 Microcomputer 7 Detection switch 12 Tracking adjustment circuit 13 Timing adjustment circuit 18 Speed control circuit 19 Phase control circuit 22 Vertical synchronization separation circuit 23 Divider circuit

Claims (1)

(57) [Claims 1] At the time of reproduction, tracking is controlled so that the reproduced control signal and the rotation phase of the rotary head have the best phase relationship by tracking adjustment means. In the magnetic recording / reproducing apparatus, an insertion detecting means for detecting that a magnetic tape has been inserted into the magnetic recording / reproducing apparatus; an ejection detecting means for detecting that a magnetic tape has been ejected; Forcibly reproducing means for forcibly bringing the tape into a reproducing state when the insertion of the tape is detected, and discharging the magnetic tape by the discharge detecting means when the tracking data adjusted by the tracking adjusting means is set to the reproducing state by the forcible reproducing means. Means for holding until the is detected, wherein during recording, the tracking data held by the holding means is provided. Further comprising a magnetic recording and reproducing apparatus, and recording means for recording a sequential control signal to the magnetic tape while adjusting the recording timing of the control signal so that the recording period is substantially the same of the control signal based on.