JP2582542B2 - Rotating head type recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type recording / reproducing apparatus, and more particularly to a rotary head type recording / reproducing apparatus capable of accessing a predetermined position on a magnetic tape at high speed.

[Prior Art] FIG. 1 is a diagram showing a tape running system in a conventional rotary head type recording / reproducing apparatus. In FIG. 1, a plurality of fixing pins 3 are provided on a traveling path of the magnetic tape 17 from the supply reel 1 to the take-up reel 2 in order to regulate the traveling of the magnetic tape 17. The magnetic tape 17 has a pin 4
Provides a predetermined tension. The guide roller 5 and the slant pin 6
The magnetic tape 17 is arranged in pairs, and regulates the magnetic tape 17 so that the magnetic tape 17 is wound around the drum 7 without being twisted stably. A pair of rotary heads 8 are mounted on the drum 7 to record or reproduce signals on the magnetic tape 17. A lead groove 9 is provided on the side of the drum 7.
Are formed, and the magnetic tape 17 runs along the lead groove 9.

An all-erasing head 10 is arranged near one guide roller 5, and an audio / video head is arranged near the other guide roller 5.
The control head 11 is arranged. In a digital audio recording / reproducing apparatus, all erasing heads are used.
10 and the audio / control head 11 may both be omitted. The audio / control head 11 forms a linear track on the magnetic tape 17 as shown in FIG.

The pinch roller 13 is pressed against the capstan 12 and serves to feed the magnetic tape 17 from the supply reel 1 to the take-up reel 2 at a constant speed. The movable portion 14 fixes the guide roller 5 and the slant pin 6 described above, and the movable portion 14 moves along the guide groove 15. It should be noted that a tape counter 16 for displaying the tape usage in conjunction with the rotation of the supply reel 1 or the take-up reel 2 is provided.

FIG. 3 is a block diagram showing an electrical configuration of a conventional rotary head type recording / reproducing apparatus. In FIG. 3, an analog signal input to an analog signal input terminal 18 is applied to an A / D conversion circuit 20 via a low-pass filter 19 for removing high-frequency components from the input signal. This A / D conversion circuit 20
Is for sampling and holding the input analog signal and converting it into a digital signal.The output of the A / D conversion circuit 20 is a memory circuit serving as a buffer memory on the recording side.
Stored in 21. An encoding circuit 22 is provided in association with the memory circuit 21, and the encoding circuit 22 is a memory circuit.
A correction code is generated or added to the data stored in 21. The coded signal stored in the memory circuit 21 is provided to a modulator 23, where a predetermined modulation is performed. The output of the modulator 23 is applied to one contact of a switch 24 for switching between recording and reproducing operations.

The rotary drum 7 is provided with a pair of recording / reproducing heads 8, and the head 8 records signals applied from the switch 24 to the magnetic tape 17. When the switch 24 is switched to the reproducing side, the signal reproduced by the head 8 is supplied to the demodulator 25 and demodulated into an encoded signal.
The output of the demodulator 25 is stored in a memory circuit 26 serving as a buffer memory on the reproduction side. A decoding circuit 27 is provided in association with the memory circuit 26. The decoding circuit 27 decodes data stored in the memory circuit 26 and performs error correction. The encoded data stored in the memory circuit 26 is provided to a D / A conversion circuit 28, where it is converted into an original analog signal. The analog signal is output from an analog signal output terminal 30 via a reproduction-side low-pass filter 29 for removing an extra signal of a high-frequency component.

The servo circuit 32 controls the drum 7 and the capstan 12 based on a clock from the master clock generation circuit 31 that generates a master clock for controlling each block.

In the PCM storage / playback device configured as described above,
The frequency at which the analog signal is sampled by the sample and hold circuit 20 is called a sampling frequency Fs,
In a device for recording and reproducing an audio signal, for example, 48 kHz, 44.1 kHz or 32 kHz is selected. Here, an example of a format of a code or a tape pattern when the sampling frequency Fs is set to 48 kHz will be described below.

Fig. 4 shows sampling frequency Fs = 48kHz, drum rotation speed
FIG. 5 is a diagram showing a one-frame configuration in the case of 1800 rpm and two heads, and FIG. 5 is a diagram showing a tape pattern when data is written on a magnetic tape in such a manner.

At the sampling frequency Fs = 48 kHz, the number of digital signal samples generated per second is 96,000 words in the case of stereo. Assuming that writing or reading on the magnetic tape 17 is performed by two heads 8 provided on the drum 7 and the rotation speed of the drum 7 is 1800 rpm, that is, 30 Hz, the number of tracks on the magnetic tape 17 is 1 second. It becomes 60 per. Therefore, the number of samples per track is
1600 words. The 1600-word data is stored in the memory circuit 21 and is encoded. For example, if one-word address code and two-word error control signal are added to eight-word data, the structure of one frame is obtained. Is as shown in FIG.

Since one frame shown in FIG. 4 includes data of eight words, data for one track is completed in 200 frames. This is shown in FIG. In FIG.
F ₀ , F ₁ ,... Each indicate a frame number.

By the way, in the above-mentioned recording / reproducing apparatus, when a high-speed access is considered, a problem is an address detection method. In a conventional method using a video tape recorder or the like, there is only a method using a tape counter synchronized with the number of rotations of a reel, and the accuracy is poor and only a guideline. Searching while looking at the image (victure search) was also slow and could not be said to be a high-speed search. Although not a rotary type recording / reproducing apparatus, for example, in a radio cassette deck or the like, a method of detecting a silent portion between music pieces (usually providing a silent region for several seconds) to perform cueing, or a method of detecting two reels There is also a method of displaying the remaining amount of tape from the ratio of the number of revolutions, but the former cannot access an arbitrary place in the music, and the latter has a drawback that the accuracy is poor.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a rotating head type recording / reproducing apparatus which can access at high speed by providing a fixed head exclusively for reproduction and counting the number of tracks.

The above and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.

[Embodiment of the Invention] FIG. 6 is a diagram showing a fixed head portion embodying an embodiment of the present invention, and FIG. 7 is a diagram showing an example of a reproduced signal obtained from the fixed head.

In FIG. 6, the read-only fixed head post 33 includes:
A fixed head 34 is mounted. On the magnetic tape 17,
When a pair of rotating heads, that is, two heads A and B are provided, a scanning track 36 is written in order by a predetermined azimuth 35 by each of the A head and the B head. Usually, azimuth recording is performed to increase the storage density. In the case where azimuth recording is performed, a read-only fixed head 34 is disposed substantially at the center of the tape 17. At this time, the azimuth of the fixed head 34 is made to match the azimuth of one of the rotary heads A and B. In the example shown in FIG. 6, the fixed head 34 is attached to the azimuth of the A head.
The azimuth is matched. In this way, by making the azimuth of the fixed head 34 coincide with the azimuth of one of the pair of rotary heads, the reproduced signal as shown in FIG. Obtained from The reproduced signal shown in FIG. 7 is equivalent to one track by the A head, and the level of the track signal by the B head is small and almost zero.

Now, assuming that the rotation speed of the drum is 1800 rpm, that is, 30 Hz and 2 heads, the number of tracks on the magnetic tape 17 is per second.
It becomes 60. Therefore, when it is desired to access S seconds ahead, 30.times.S counts may be performed in FIG.

Also, when it is desired to play back from the Nth second ahead of the L tune, the following is performed. FIG. 8 is a block diagram showing an electrical configuration in such a case. The same components as those in FIG. 3 shown in the conventional example are denoted by the same reference numerals and description thereof will be omitted.

In the figure, reference numeral 37 denotes a silent part detecting means for detecting a silent area for several seconds in which a reproduction signal from the fixed head 34 is not detected as a silent part between music pieces, and 38 denotes a counting means for counting the number of tracks read based on the reproduction signal. It is.

First, by searching for a silence portion from the reproduction signal of the fixed head 34, a desired L tune is searched for, and then (30 × N) is accessed based on the reproduction signal as described above, so that the magnetic tape is accessed. Reproduction can be performed from a desired position on 17.

When the magnetic tape 17 is fed at a high speed, the contact with the head is deteriorated. Therefore, it is preferable that the fixed head 34 is arranged so as to be substantially at the center of the magnetic tape 17.

The drum rotation speed of 1800 rpm and the value of 2 heads are values that change depending on the system. At the time of this high-speed access, the rotating head may be stopped so as not to touch the magnetic tape 17 in order to avoid head wear.

[Effects of the Invention] As described above, according to the present invention, the read-only fixed head having the azimuth angle equal to the azimuth angle of at least one of the rotary heads is provided at the center of the track on the magnetic tape. Since they are arranged to face each other, the number of tracks recorded by the rotating head is detected by the fixed head for reproduction only, and the silent part between the songs is detected, high-speed access is possible, and the entire apparatus can be inexpensive, High accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a recording / reproducing apparatus using a rotary head. FIG. 2 is a diagram showing the tape pattern. FIG. 3 is a diagram showing an electrical configuration of a PCM recording / reproducing apparatus using a rotating head. FIG. 4 is a diagram showing one frame configuration in the case of a sampling frequency F _S = 48 kHz, a drum rotation speed of 1800 rpm, and two heads. FIG. 5 is a diagram showing a tape pattern when writing is performed on a magnetic tape in this manner. FIG. 6 is a drawing showing a fixed head portion embodying an embodiment of the present invention. FIG. 7 shows a reproduction signal obtained from the fixed head. FIG. 8 is a diagram showing an electrical configuration of a PCM recording / reproducing apparatus using a rotary head according to one embodiment of the present invention. In the figure, 7 is a drum, 8 is a rotary head, 11 is a capstan, 17 is a magnetic tape, and 34 is a fixed head.

Continuation of the front page (56) References JP-A-56-111174 (JP, A) JP-A-57-6478 (JP, A) JP-A-50-75320 (JP, U) , B2) Japanese Patent Publication No. 58-40255 (JP, B2)

Claims (1)

(57) [Claims] 1. A drum provided with at least two rotary heads having different azimuth angles, and an azimuth angle equal to the azimuth angle of at least one of the rotary heads, and recording is performed by the rotary head. A read-only fixed head disposed so as to face the center of the track on the read magnetic tape, counting means for counting the number of tracks read based on a reproduction signal reproduced by the read-only fixed head, A silent portion detecting means for detecting a silent region for a fixed period in which a playback signal is not detected by the playback-only fixed head as a silent portion between songs, and after performing the cueing of a desired song by the silent portion detecting device, Accessing information after a predetermined time in the desired music based on the number of tracks counted by the counting means; A rotary head type recording / reproducing apparatus characterized by the above-mentioned.