JPS61255550A - Revolving head type recording and reproducing device - Google Patents

Abstract

PURPOSE:To stabilize an access signal during high-speed retrieving with economical constitution by variably controlling the revolutionary speed of a drum with use of the envelope of a reproduction signal varying associatively with the tape speed so as to keep the relative speed of a head and the tape constant. CONSTITUTION:In the normal reproduction operation, a switch 39 turns on, the output of a differential amplifier 41 is zero because the output from an envelope detection circuit 37 is inputted to both of first and second peak holder circuits 38 and 40, and hence no control voltage is supplied to a servo system. Therefore, a drum motor 43 rotates at a constant speed. On the contrary, the switch 39 turns off during the high-speed retrieving, and the output from the detection circuit 37 is inputted to the first peak holder circuit 38, but in the second peak holder circuit 40 is an envelope peak level value during the normal reproduction operation held. These peak level values are compared by the amplifier 41, and its result is amplified to be supplied to the servo system. Accordingly, the servo system controls the motor drive circuit 42 with the voltage that includes the said differential voltage. As a result, a stable signal of a value approximately equal to that during the normal reproduction operation is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rotary head type recording/reproducing device, and in particular to a variable speed drum equipped with a rotary head when searching at high speed a magnetic tape recording information such as an audio signal. This relates to a reproduction method.

[Conventional technology]

In general, there are two possible methods for recording and reproducing information signals, such as audio signals, by using a fixed head and by using a rotating head to sequentially form diagonal tracks on a tape.

When a rotating head is used, signals are recorded by sequentially forming trunks diagonal to the longitudinal direction of the tape, rather than one continuous track as in the fixed head system. Therefore, signals can be easily time-compressed and recorded without wasting tape.

The general configuration of a rotary head type recording/reproducing device is shown in Figures 9 to 1.
Shown in Figure 3. VTRPDAT is a typical example of this rotary head type recording/reproducing device.

In FIG. 9, 1 is a supply reel, 2 is a take-up reel,
3 is a fixed guide provided to regulate the running of the tape, and 4 is a guide for tape tension control. Guide rollers 5 and head angle guides 6 are arranged in pairs on the left and right to regulate the tape 17 so that the tape 17 can be stably wound around the drum 7 without twisting. A rotary head 8 is attached to the drum 7, and signals are recorded onto and reproduced from the tape 17. 9 is a lead groove provided on the side of the drum 7, and as soon as the tape 17 runs along this lead groove 9, 10 corresponds to an all-erase head, and 11 corresponds to an audio, control, and cue head in the case of a VTR. This head 11 forms a linear trunk T1 on the tape 17 as shown in FIG. 12 is a capstan, and the pinch roller 13 is pressed against this capstan 12 and serves to feed the tape 17 to the take-up reel at a constant speed. For digital audio, all erase head 10. It may also be abbreviated as control head ll. 14
15 is a guide groove; 16 is a tape counter linked to the reel 1 or 2;

Next, regarding signal processing, the general configuration when using the PCM transmission method is shown in FIG. In the figure, 18 is an analog signal input terminal, 19 is a low-pass filter for cuffing high frequency components of the analog input signal on the recording side,
20 is an analog-digital (A/D) for sample-holding analog signals and converting them into digital signals.
A conversion circuit, 21 is a buffer memory circuit on the recording side, 22 is an encoding circuit for generating and adding a correction code to the data stored in the memory circuit 21, and 23 is a modulation circuit for modulating the encoded signal. Vessel, 24 is a record.

This is a switch for changing playback operation. Also, 7
8 is a rotating drum, 8 is a recording/reproducing head provided on the drum 7, 17 is a magnetic tape, and 12 is a capstan for feeding the tape 17 at a constant speed. 25 is a demodulator for demodulating the reproduced signal, 26 is a buffer memory circuit on the reproduction side for sequentially storing the signal demodulated by the demodulator 25, and 27 is a buffer memory circuit for storing the data stored in the buffer memory circuit 26. a decoding circuit for decoding and error correction; 28;
2 is a digital-to-analog (D/A) conversion circuit for returning the decoded data to the original analog signal; 29 is a reproduction-side low-pass filter for removing excess high-frequency signals; and 30 is an analog signal output terminal. , 31 is a mask clock generation circuit that generates a master clock for controlling each block, and 32 is a drum 7 and a capstan 12.
This is the servo circuit that controls the

In such a PCM recording and reproducing apparatus, an example of the code and tape pattern format when the sampling frequency is 48 KHz will be described below. At a sampling frequency of 48 KHz, the number of samples of digital signals generated per second is 96,000 words in the case of stereo. Writing and reading on the tape are performed by two heads 8 provided on the drum 7, and the number of rotations of the drum 7 is controlled.
If the speed is 180 Orpm, the number of trunks on the tape is 1.
That's 60 lines per second. The number of samples included in one track is 1600 words. These 1600 words of data are stored in the memory circuit 2 and encoded. For example, for 8 words of data, 1 word of address code, 2
If a word error correction signal is added, the structure of one frame will be as shown in FIG. One frame in Figure 12 contains 8 words of data, so 20
One track's worth of data is completed at frame 0. Also,
Items closely related to PCM data, such as the number of channels, sampling frequency, control of PCM data, etc., such as block addresses, and subcode frames containing time information such as time codes and song information are added. For example, a track shown in FIG. 13 is constructed. Reading this information enables high-speed searches. In FIG. 13, 33 is a frame area containing the data information shown in FIG. 12, and 34 is a subcode frame area containing access signals, etc.

[Problem that the invention seeks to solve]

When considering high-speed retrieval of several hundred times speed in this type of recording/reproducing device, the speed of conventional VTR is at most 30 times, and the information on the linear track shown in FIG. It was one of the so-called picture searches where you search while looking at the playback screen. Although it is not a rotating head type recording/playback device, for example, in radios, cassette decks, etc., there is a method of detecting the silent part between songs (usually a silent area of several seconds) and locating the beginning of the song, and a method that uses two reels. There is also a method of displaying the remaining amount of tape from the rotation speed ratio of There was a drawback.

In addition, in the case of PCM recording, it is possible to input high-speed search signals into the tracks as shown in Figure 13, but in the past, such devices were not compatible with the new standard for rotary head digital audio recorders. This is what is currently being proposed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device that can stably reproduce high-speed search signals provided on a track as described above using a rotary head.

[Means for solving problems]

In the rotary head type recording and reproducing device according to the present invention, in order to match the band of signals recorded on the tape with the head and the reproducing circuit including the rotary transformer, the relative speed between the rotary head and the tape is almost constant. To be constant,
The drum rotation speed can be varied in conjunction with the tape speed.

[Effect]

In this invention, the difference in the relative speed between the head and the tape during each playback is detected by comparing the high-frequency envelope level during normal playback with the envelope level obtained during high-speed playback, and the difference obtained based on the difference is detected. Since the dynamic voltage is additionally applied to the drum drive motor, the drum rotation is controlled so that the relative speed between the head and the tape is approximately constant.

〔Example〕

Here, before explaining the present invention in detail, for example, as shown in FIG. 2, two heads are mounted on the drum 7,
The principle of the present invention will be explained by taking as an example the case where the tape wrapping angle is 90 degrees. This is proposed as a digital audio chip recorder.

During normal playback, the rotary head 8 traces the scanning track as shown in FIG. In FIG. 3, 44 indicates the head scanning direction during normal reproduction, 45 indicates the head scanning direction during forward high speed search, and 46 indicates the gutter scanning direction during reverse high speed search. As is clear from the figure,
During high-speed search, the signal is reproduced across a plurality of scanning tracks, and the reproduced signal envelope in this case is shown in FIG. 4(b). As explained in Fig. 2, since the tape winding angle is 90° and there are 2 heads, the playback signal is intermittently generated, and during normal playback, the envelope 4 has no constriction.
7 (see FIG. 4(a)) is obtained.

On the other hand, when searching for crystal speed, a constriction occurs by the number of scanning tracks spanned. In FIG. 4('b), 48 indicates a reproduced signal per scanning track, and 49 indicates the envelope of the signal obtained during high-speed search.

Here, regarding the reproduction response, those related to the head and throat are shown in FIG. 5, and those related to the transformer are shown in FIG. In the figure,
50 indicates losses during recording such as core loss and recording demagnetization, and 51 indicates losses during reproduction such as separation loss called air gap loss and spacing loss. The reproduction response increases as the frequency increases, but due to the loss 50.51, the peak 5
2 and decreases thereafter. Further, signals are exchanged using a rotary transformer next to the head, and its membrane characteristics are shown in FIG. Since there is a resonance point 53 in the high frequency range, it is necessary to avoid this especially in the case of digital recording and to use a flat band 54 as the signal region. Regarding the relative speed between the head and the tape, it is known that, in principle, the reproduction response is related to the relative speed. Regarding the recording wavelength in FIG. 5, it can be seen that the relative speed between the head 8 and the tape 17 should be kept constant until the wide area loss is eliminated.

The present invention has been made based on such a principle, and a first embodiment of the present invention will be described below with reference to FIG. 1. In the figure, 8 is a rotary head, 35 is an output amplifier of the rotary head 8, and 36 is a filter for extracting only a predetermined frequency band of the reproduced signal, and this passband is set depending on the usage condition. That is, depending on the usage conditions, if the signal detection circuit 37 described later takes the envelope of the entire band, there may be no apparent variation, and there is a possibility that the desired correction may not be possible. For this reason, only signals in a certain predetermined frequency band are extracted by the filter 36 depending on the state of use. 37 is a signal detection circuit; 38 is a first peak hold circuit for determining the peak level of the signal output from the detection circuit 37;
9 is a switch switching circuit that is turned on during normal playback and turned off during high-speed search; 40 is a second peak hold circuit for determining the peak level of the signal obtained through this switch switching circuit 39; A differential amplifier 42 compares the envelope peak level value during normal playback with the envelope peak level value during high-speed search, and amplifies the resulting difference.
Drum motor drive circuit to which addition is applied via 0, 43
indicates a drum motor. 32 is a servo circuit that keeps the rotation of the drum motor 43 constant during normal playback and recording, controls the drum rotation speed according to the difference signal from the differential amplifier 41 during high-speed search, and operates so that the above signal becomes zero. It is.

Next, the operation will be explained.

The signal reproduced by the rotary head 8 is amplified by an amplifier 35, a predetermined band is extracted by a filter 36, and the extracted signal is input to an envelope detection circuit 37.

In the detection circuit 37, an envelope 47 as shown in FIG. 4(a) is detected during normal playback, and an envelope 49 as shown in FIG. 4 during high-speed search is detected as described above.

First, during normal reproduction, the switch 39 is turned on, and therefore the output of the envelope detection circuit 37 is input to both the first and second peak hold circuits 38 and 40. Therefore, the output of the differential amplifier 41 is 0,
No control voltage is applied to the servo system, and the drum motor is rotated at a constant speed.

On the other hand, during high-speed search, the switch 39 is turned off, so the first
The output of the detection circuit 37 is input to the peak hold circuit 38, and the envelope peak level value during normal reproduction is held in the second peak hold circuit 40. These peak level values are then compared by a differential amplifier 41, and the comparison result is amplified and provided to the servo system. Therefore, in the servo system, the motor drive circuit 42 is controlled by the voltage to which the differential voltage is applied. In this way, the relative speed between the head and the tape during high-speed retrieval is approximately equal to that during normal playback, and a stable playback signal can be obtained.

In the device of this embodiment, during high-speed search, the drum rotation speed is controlled by the envelope of the playback signal that varies in conjunction with the tape speed, so that the relative speed between the head and the tape is kept constant. , with an inexpensive configuration,
Stable access signals can be obtained during high-speed searches.

FIG. 7 shows a second embodiment of the present invention, which is an effective device for use in analog FM recording. In the figure, the same reference numerals as in Figure 1 indicate the same or corresponding parts, and 5
5 is a carrier wave frequency detection circuit, and 56 is a circuit that outputs a carrier wave frequency reference value.

In the embodiment of the apparatus having such a configuration, attention is paid to the intercarrier wave number of the FM signal, this is compared with a reference value, and the drum rotation is changed based on the difference signal to maintain a constant relative speed between the head and the tape. Apply the servo so that Therefore, even with the device of this embodiment, the relative speed between the head and the tape can be kept constant during high-speed retrieval, and the same effects as in the above embodiment can be obtained.

In the above embodiment, a method using track signal detection has been described, but the relative speed is obtained by a linear relationship with respect to the drum rotation speed and tape speed. In other words, if the tape speed can be detected, the drum rotation speed can be made variable based on that information, and the relative speed can be kept constant. FIG. 8 shows an embodiment made with attention to this point. This example is
For example, a tape speed detection means 57 obtained from the reel rotation speed is provided, and the drum rotation speed calculation means 5
8, the drum rotation speed at which the relative speed is constant is obtained, and this is compared with the current drum rotation speed obtained by the drum rotation speed detection means 59, and the drum rotation speed is controlled based on the difference signal. Of course, this embodiment also provides the same effects as the above embodiment.

〔Effect of the invention〕

As described above, according to the present invention, the drum rotation speed is varied by the envelope of the playback signal that changes in conjunction with the tape speed, and the relative speed between the head and the tape is kept constant. This configuration has the effect of providing a stable access signal during high-speed searches.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a rotary head type recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing a tape bus system around a drum, FIG. 3 is a diagram showing a tape pattern, and FIG. al (bl is a schematic diagram of the reproduction signal during normal reproduction and high-speed search, respectively; Figure 5 is a diagram showing the reproduction response of the head; Figure 6 is a diagram showing the reproduction response of the rotary transformer; Figures 7 and 8 FIG. 9 is a block diagram showing another embodiment of the present invention, FIG. 9 is a schematic diagram of a tape path system of a conventional rotary head type recording/reproducing device, FIG. 10 is a diagram showing a conventional tape pattern, and FIG. 11 is a diagram showing a conventional tape path system. A diagram showing the general configuration of the signal processing system when using the PCM transmission method, Figure 12 shows the PCM signal 1
FIG. 13 is a diagram showing the structure of a frame, and FIG. 13 is a diagram showing the structure of a trunk recorded on a tape. 7...Drum, 8...Head, 17...Tape,
37...Envelope detection circuit, 38.40...Peak hold circuit, 41...Differential amplifier, 42...
Motor drive circuit, 55...Carrier frequency detection circuit, 5
6... Carrier wave frequency reference value, 57... Tape speed detection means, 58... Drum rotation speed calculation means, 59...
・Drum rotation speed detection means. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (5)

[Claims] (1) In a rotary head type recording and reproducing device that records and reproduces signals on a tape-shaped recording medium using a rotary head, a drum drive control means that drives and controls a drum on which the rotary head is mounted;
Difference signal output means for comparing the head and inter-tape relative speed during high-speed playback with that during normal playback and outputting a difference signal; A rotary head type recording/reproducing apparatus comprising: a correction means for applying the difference signal as a control signal to the drum drive control means so as to be equal to the difference signal. (2) The difference signal output means is characterized in that it compares the envelope level of the normal playback signal and the envelope level of the high-speed playback signal to detect the difference in relative speed between the head and the tape during each playback. A rotary head type recording/reproducing device according to claim 1. (3) The rotary head type recording and reproducing apparatus according to claim 2, wherein the difference signal output means compares envelope levels of predetermined frequency bands of each reproduced signal. (4) The signal recorded on the recording medium is an analog FM
The difference signal output means compares a carrier wave frequency reference value with a carrier wave frequency during high-speed playback to detect a difference in relative speed between the head and the tape during each playback. A rotary head type recording/reproducing device according to claim 1. (5) The difference signal output means detects the tape speed, calculates the drum rotation speed at which the relative speed between the head and the tape is the same during normal playback and high-speed playback, and calculates the difference between this and the actual drum rotation speed. A rotary head type recording/reproducing apparatus according to claim 1, wherein the rotary head type recording/reproducing apparatus outputs a difference.