JPS6061953A - Rotary head type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the accurate searching by using the field number without providing especially a track on a tape to record the field number, by detecting and counting the peaks of an envelope signal which is reproduced in a high speed feed mode of the tape. CONSTITUTION:A contact between a reproduction head and a tape in the rapid traverse and rewind modes. Then plural tracks are crossed while a head is switched, and a reproduction signal is obtained as shown in the figure. The peak of the envelope of the reproduction signal is equivalent to a field. In other words, a field count pulse generating circuit 8 slices a reproduced envelope signal at a fixed level in order to count the fed fields. Then a field count pulse is produced and supplied to a field counting circuit 9 to count the fields. The circuit 9 sets the field number at a stop time point and adds the counted field number to the set field number in accordance with the rapid traverse or rewind mode. Thus the present field number is obtained. This field number is outputted to an address comparator 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head type magnetic recording/reproducing device such as a video tape recorder.

Conventional configurations and their problems Conventionally, magnetic tape recording in video tape recorders, etc. (1) SMPTE (5ocity
of Motion Picture and Te1
(Evision Engineer) A method of recording and using time code, a method of counting a constant frequency signal from a control track used for synchronization, a method of detecting the rotation of a tape winding reel motor or a supply reel motor and converting it into an electrical signal. A method is used in which the signal is converted into a signal, and this signal is detected and counted. SMPTE
In the method using time code, it is necessary to separately provide a track for recording the time code, and a circuit device for recording the time code and a circuit device for reproducing and demodulating the time code are also required. Particularly, in order to reproduce and demodulate at high or low speed during reproduction, there is a disadvantage that the circuit device becomes complicated.

As for the method of counting control track signals, in recent years video tape recorders have adopted a method of synchronizing without providing a control track. Providing one is disadvantageous in terms of cost.

(2) In the method of detecting the rotation of a motor, etc., the deviation from the position on the tape depends on the mechanical accuracy, so it is difficult to perform accurate positioning.

Incidentally, in recent years, video tape recorders (hereinafter referred to as VTRs) have been developed that record and reproduce digital signals obtained by converting audio signals and video signals.

This VTR will be explained using FIGS. 1 and 2. FIG. 1 is an explanatory diagram of the relationship between the head and the tape, and FIG. 2 is an explanatory diagram of the recording state on the tape. By converting analog audio signals to digital signals, signal division,
Since merging can be easily performed, it becomes possible to record the digital signal simultaneously with the video signal on the video track of a VTR capable of recording and reproducing video signals, as shown in FIG. For this purpose, as shown in FIG. ) or (3) is recording or reproducing a video signal, the other head (3) or (2) may be capable of recording or reproducing a digital signal (3). An audio signal corresponding to a period of one field of video No. 11 is recorded as a digital signal before one feed μ of the video signal. This digital signal includes audio digital! Digital data may be added to implement various types of control and signal processing other than signals. For example, if a field number is entered, the video signal can be edited with high precision. In FIG. 2, (a) is a video signal, and (b) is a digital signal.

In the case of such a VTR, there is no need for a conventional linear track for recording audio signals, and it becomes possible to record video and audio using only a rotary head. However, in such VTRs, positioning such as cueing can be done while playing the field numbers, but in order to feed the tape at high speed and do it in a short time, it is necessary to set the field numbers accurately even during high-speed feeding. There were difficulties that had to be regenerated.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional art, and provides a rotary head type magnetic recording/reproducing device for recording a digital μ signal and a video signal on the same track in a time-division manner. It is an object of the present invention to provide a rotary head type magnetic recording/reproducing device capable of determining a field number without reproducing the field number at the time of 9th transmission, and capable of locating the beginning of a video signal of a predetermined field number.

Structure of the Invention In order to achieve the above object, the rotating head type magnetic recording/reproducing device of the present invention provides a reproduction signal obtained when reproducing at high speed adjacent discontinuous recording tracks sequentially recorded on a magnetic tape by a rotating magnetic head. a detection means for detecting the envelope of the envelope, a determination means for detecting that the envelope is larger than a certain level, a counting means for counting the signals obtained from the determination means, and a count value obtained by the counting means in advance. The configuration includes a comparison means that adds or subtracts from the set first value and compares it with a preset second value.

Description of Embodiment (5) Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 3 is a circuit diagram of the main parts of a rotary head type magnetic recording and reproducing device according to an embodiment of the present invention, in which (5) is a video FM signal demodulation circuit, (6) is a digital signal demodulation circuit, and (7) is an envelope. (8) a u-field counting pulse generation circuit; (9) a field counting circuit; (10, an address comparison circuit; and Qη, a control circuit).

When performing cue control, first the field number to be cued is set in the address comparison circuit aO.

Next, the tape moves to cylinder A at the position where the tape is currently stopped.
The field number is demodulated from the reproduction signal of the digital data recording section by the digital data demodulation circuit (6) and sent to the address comparison circuit section. The address comparison circuit Q□ compares the two field numbers and sends a fast forward or rewind command to the control circuit Qυ depending on the magnitude of the field number comparison. The tape is fast-forwarded or rewound based on commands from the control circuit αη. The playback signal during normal tape forward playback is shown in Figure 4 (6). However, if the playback head is kept in contact with the tape during fast forwarding or rewinding, the
Since a plurality of tracks are crossed as shown by the broken line in FIG. 2, a reproduced signal is obtained as shown in FIG. 5. When the envelope of this reproduced signal is extracted by the envelope reproduction circuit (7), one peak of this envelope corresponds to one field. In order to count the number of peaks, that is, to count the number of sent fields, a field count pulse is generated by slicing the reproduced envelope signal at a constant level in a field count pulse generation circuit (8). This field counting pulse is supplied to a field counting circuit (9) to count the number of fields. In the field counting circuit (9), the field number at the time of stopping is set, and the counted number of fields is added to or subtracted from this field number according to fast forwarding or rewinding, and the current field number is calculated. Address comparison circuit 01
Output to. At the beginning of the address comparison circuit, the field number from the field counting circuit (9) to be searched is compared (7), and it is determined whether the difference is within a certain range.
This result is sent to the control circuit 0υ. The control circuit (11) is
Based on this result, a control command is output to set the tape feeding speed to normal playback. In the normal reproduction state, the reproduction envelope is constant as shown in FIG. 4, and no field count pulse is generated, so the field number is reproduced by demodulating the digital data by the digital signal demodulation circuit (6). The address comparison circuit 00 detects that the reproduced field number matches the set fee yvltft1, and sends a command to the control circuit Qη to stop tape feeding, thereby ending the tape cueing.

In this way, according to this embodiment, the peaks in the envelope signals that are played back when the tape is sent faster than usual are detected and the number of peaks is counted, so a field number is specially recorded on the tape. It is possible to accurately locate the cue by field number without providing a track. In addition, since demodulation is not required when the tape is sent faster than normal, a demodulation circuit (8) for high-speed playback is not required (9), and the circuit configuration is simplified.

In the above embodiment, the reproduction envelope of the video signal portion is used, but the same implementation can be made using the reproduction envelope of the digital data portion. In this case, the reproduction envelope is generated intermittently, and the number of peaks and the number of sent fields vary depending on the tape feed speed and the length of the digital data portion, but there is no one-to-one correspondence. #) It can be realized by considering the count.

As described in detail, according to the present invention, there is a detecting means for detecting the envelope of the reproduced signal during high-speed reproduction, a determining means for detecting that the envelope is larger than a certain level, and a method for detecting the envelope of the reproduced signal during high-speed reproduction. means for counting the signals obtained by the counting means, and a preset first count value obtained by the counting means.
Since a comparison means is provided for adding or subtracting the value to the value and comparing it with a preset second value, the positioning information for locating the beginning of the signal recorded on the recording medium can be calculated using a special method (9). It can be obtained accurately without using a track or requiring a demodulation circuit for high-speed reproduction, and its industrial value is extremely high.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the relationship between the head of a rotating head type magnetic recording and reproducing device and a tape, FIG. 2 is an explanatory diagram of signals recorded on the tape, and FIG. 3 is a diagram of rotation in an embodiment of the present invention. FIG. 4 is a circuit block diagram of the main parts of the head-type magnetic recording/reproducing device, and FIG. 4 is a signal waveform diagram during normal reproduction in the same embodiment.
The figure shows the demodulation circuit of the same embodiment, (7)...Envelope regeneration circuit, (8)...Field counting pulse generation circuit (judgment means), (9)...Field counting circuit (counting means), 01.・Address comparison circuit (comparison means), αη
...Control circuit agent Yoshihiro Morimoto (10) Figure 1 4z Figure 3

Claims (1)

[Claims] 1. Detection means for detecting the envelope of a reproduced signal obtained when adjacent discontinuous recording tracks sequentially recorded on a magnetic tape by a rotating magnetic head are reproduced at high speed, and the envelope is larger than a certain level. a determining means for detecting a signal obtained by the determining means; a counting means for counting the signal obtained by the determining means; A rotary head type magnetic recording/reproducing device comprising a comparison means for comparing the value of .