JPH05236417A - High-speed search controller - Google Patents

Abstract

PURPOSE:To improve search speed limit by increasing the limit value of tape speed in the case of high-speed search by fluctuating a reproducing head in a cycle synchronized with the rotation of a rotary drum by a head actuator. CONSTITUTION:A magnetic tape 1 helically recorded by a recording head 1 fitted to a rotary drum 5 at prescribed tape speed is driven in the direction of an arrow 13 by a capstan shaft 3. The magnetic tape 1 is wound around the rotary drum 5 to be rotated in the direction of an arrow 14, over 180 deg., and a head actuator 6 to move a reproducing head 7 is installed at the drum 5. On the other hand, a hole element 9 is provided opposite to an (m) -pole magnetized magnet disk 8 to be rotated integrally with the drum 5. Pulse signals generated by the element 9 are inputted to a cyclic counter 10. The count value of the counter 10 is D/A converted 11 and impressed to the head actuator 6. Namely, the reproducing head 7 is driven in a sawtooth form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed search controller for a video tape recorder (hereinafter referred to as VTR).

[0002]

2. Description of the Related Art In order to construct a noise-free screen over a range of tape speeds, a conventional high-speed search control device in a VTR having a head actuator that changes the reproducing head so as to follow a helical track, When exceeding the tape speed without noise, the head actuator was stopped and a high speed search was performed.

[0003].

According to the conventional high speed search control device, it is necessary to trace at least the track of the unit data length area when the reproducing head crosses the helical track during the high speed search, so that the tape speed is increased. Limits naturally occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high speed search control device for increasing the search speed limit by increasing the tape speed limit value during high speed search.

[0005]

In order to achieve the above object, a high speed search control device of the present invention divides a digital signal into predetermined unit data lengths by a recording head that rotates integrally with a rotating drum on a magnetic tape. Then, helical scanning recording is performed, and a reproducing head that rotates integrally with the rotary drum is moved in a direction substantially perpendicular to the helical track to enable noiseless reproduction up to N times (N is a real number) tape speed at the time of signal recording. And a head actuator for moving the reproducing head in a cycle synchronized with the rotation of the rotary drum even when reproducing at a high tape speed exceeding N times the tape speed at the time of signal recording. is there.

[0006]

According to the high speed search control device of the present invention, even when reproducing at a high tape speed exceeding the N times tape speed capable of noiseless reproduction, the head actuator synchronizes the reproducing head with the rotation of the rotary drum. Because of the variation, the range that can be traced when the reproducing head crosses the helical track is increased, and as a result, the tape speed can be increased.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high speed search control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the high speed search control device of the present invention.

In FIG. 1, a magnetic tape 1 helically recorded by a recording head 15 attached to a rotary drum 5 at a predetermined tape speed includes a pinch roller 4 and a motor 2.
It is driven in the direction of arrow 13 by the capstan shaft 3 directly connected to. The magnetic tape 1 is wound around a rotary drum 5 rotating in the direction of arrow 14 by 180 degrees by a winding means (not shown), and a head actuator 6 for moving a reproducing head 7 is installed on the rotary drum 5. To be done. Further, a hall element 9 is provided so as to face the magnet disk 8 magnetized with m (m is a positive even number) magnet that rotates integrally with the rotary drum 5. As a result, the Hall element 9 generates m / 2 pulse signals per one rotation of the rotary drum in synchronization with the rotary drum 5. Hall element 9
The pulse signal generated by is input to the cyclic counter 10 which is reset to zero by one cycle with m / 4 pulse inputs. The count value of the cyclic counter 10 is converted into an analog signal by the D / A converter 11 and the amplifier 12
The voltage is amplified by and then applied to the head actuator 6. That is, the reproducing head 7 is the rotating drum 5
It is driven in a sawtooth wave shape in synchronization with the rotation of.

FIG. 2 is a concept showing a relative relationship between the helical track recorded on the magnetic tape 1 and the scanning locus of the reproducing head 7 when the magnetic tape 1 is run at a tape speed higher than that at the time of recording. It is a figure. Now, when the head actuator 6 is not driven, the reproducing head 7 draws a scanning locus 24 on the helical track 21 recorded on the magnetic tape 1 at a tape speed.
FIG. 3A shows the envelope of the reproduction signal obtained by the reproduction head 7 when the area 22 in which the signal of the unit data length is recorded is scanned as shown in FIG. In this case, the maximum value of the drop of the envelope 31 of the reproduction signal of the area 22 in which the unit data length is recorded is −
6 dB, envelope 3 in the front and back areas
The levels of 2, 33 are -6 dB or less.

Now, in (FIG. 2), when the magnetic tape 1 is run at the same tape speed as in the above case, the head actuator 6 reproduces data so that the scanning locus 25 of the reproducing head 7 is obtained. When the head 7 is varied in synchronism with the rotary drum 5, the envelope of the reproduction signal obtained by the reproduction head 7 when the areas 22 and 23 in which the signals of the unit data length are recorded are scanned as shown in FIG. (FIG. 3) B. In this case, the drop of the envelope 41 of the reproduced signal of the area 22 in which the unit data length is recorded and the envelope 42 of the reproduced signal of the area 23 in which the continuous unit data length is recorded is −6 dB, The level of the envelopes 43 and 44 to be set is -6 dB or less.

For example, if the operation of a signal processing circuit (not shown) connected below is compensated when the level drop of the reproduction signal from the reproduction head 7 is -6 dB or less, the reproduction head 7 is not moved. The limit value of the tape speed at the time is the scanning locus 2 in the area where the signal of the unit data length is recorded.
4 results in the assumed tape speed in the only scan possible (FIG. 2). However, when the scanning locus 25 is obtained by the high speed search control device of this embodiment, the tape speed limit value is twice the tape speed assumed in FIG.

[0012]

As described above, according to the high speed search control device of the present invention, the reproducing head is rotated by the head actuator even when reproducing at a high tape speed exceeding the N times tape speed capable of noiseless reproduction. Since it is changed in synchronization with the rotation of the drum, the range that can be traced when the reproducing head crosses the helical track is increased, and as a result, the tape speed can be increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a high-speed search control device of the present invention.

FIG. 2 is a conceptual diagram showing a relative relationship between a helical track recorded on a magnetic tape and a scanning track of a reproducing head.

FIG. 3A is a waveform diagram of a reproduction envelope when the head actuator is not driven. FIG. 3B is a waveform diagram of a reproduction envelope when the head actuator is driven.

[Explanation of symbols]

 1 Magnetic Tape 2 Motor 3 Capstan Shaft 4 Pinch Roller 5 Rotating Drum 6 Head Actuator 7 Playback Head 8 Magnet Disk 9 Hall Element 10 Cyclic Counter 11 D / A Converter 12 Amplifier 15 Recording Head

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Osamu Yamaguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A reproducing head, which rotates integrally with the rotary drum, is formed by recording a digital signal on a magnetic tape by a recording head that rotates integrally with the rotating drum, dividing the digital signal into predetermined unit data lengths for helical scanning recording. The tape speed is higher than the tape speed N times when recording a signal, and is equipped with a head actuator that moves in a direction substantially vertical with respect to the signal recording and performs noiseless reproduction up to a tape speed N times (N is a real number) during signal recording. The high-speed search control device characterized in that the reproducing head is varied by the head actuator in a cycle in synchronization with the rotation of the rotary drum during reproduction.