JPH04209308A - Reproducing device - Google Patents

Abstract

PURPOSE:To promote retrieval speed by performing the waveform equalization, selection, reproduction and write of both retrieval data of outward and return courses. CONSTITUTION:Return course reproducing magnetic heads 22a and 22b are provided in addition to outward course reproducing magnetic heads 20a and 20b. Now, a regenerative signal from a return course data area is most suitably waveform-equalized by a waveform equalizing circuit 42, while a regenerative signal from a return course data area is most suitably waveform-equalized by a waveform equalizing circuit 44, whereas a most suitably waveform equalized signal is selected by a switch 46. Then, since reproducing outputs of the magnetic heads 20a, 22a, 20b and 22b are supplied in turn at intervals of 180 deg., a memory 50 is written in the forward half of 90 deg., and is read out in the backward half of 90 deg.. Now, the outputs of the magnetic heads 22a and 22b are inverted in order of data, but they are inverted to be in normal order by a memory address control.

Description

[Detailed description of the invention]

[00011

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing apparatus, and more specifically to an apparatus for reproducing information digitally recorded on a tape-shaped recording medium. [0002] A digital audio tape recorder is a device for digitally recording information such as audio, images, data, etc. on a tape-shaped recording medium, such as a magnetic tape. This is a magnetic tape similar to a VTR cassette.
Digital audio signals are recorded on a magnetic tape housed in a cassette using a helical scan method using a rotating drum, and each track extends over almost the entire width of the tape. Further, the tape feeding direction for recording and reproduction is limited to one direction. [0003]

As described above, in the conventional digital recording and reproducing apparatus, the tape feeding direction for recording and reproducing is limited to one direction, and reciprocating recording and reproducing is not possible. Therefore, there is also the disadvantage that it takes time to retrieve recorded information. [0004] In response to this, a recording method has also been proposed in which the tape is divided into two parts depending on the tape width, thereby enabling recording and reproduction in different tape running directions. Even with this type of recording method, the disadvantage that searching takes time cannot be overcome because magnetic tape is basically a sequential access medium. [00051] An object of the present invention is to provide a reproducing apparatus that can search recorded information more quickly in a recording system that allows reciprocating recording and reproducing. [0006]

[Means for Solving the Problems] A playback device according to the present invention is used in a recording system that divides a tape-shaped recording medium into a plurality of areas in the tape width direction and records information in predetermined areas according to the tape running direction. The reproducing apparatus is characterized in that it includes a predetermined number of magnetic heads for reproducing in the same direction as when recording, and a predetermined number of magnetic heads for reproducing in the opposite direction to the direction during recording. [0007]

[Operation] With the above means, it is possible to reproduce data recorded in an area in which the tape running direction is opposite. Therefore, the recorded contents can be searched without reversing the tape, and the search speed can be increased. [0008],

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. [00091] FIG. 1 is a plan view of a rotary head and a magnetic tape cassette in an embodiment of the present invention, and FIG. 2 is a developed view of the rotary head in the circumferential direction. 10 is a tape cassette, and a magnetic tape 16 is wound between two reels 12 and 14. 18 is a rotating drum to which magnetic heads 20a, 20b; 22a, 22b are attached. Magnetic heads 20a, 22a and magnetic head 20b
, 22b have different azimuths. [00101 As can be seen from FIG. 2, the magnetic head 20a
The magnetic heads 22a and 22a are mounted facing each other at 180 degrees on the circumferential surface of the rotating drum 18, and similarly, the magnetic heads 20b and 22b are mounted facing each other at 180 degrees on the circumferential surface of the rotating drum 18. The magnetic heads 20a, 20b and the magnetic heads 22a, 22b are mounted on the circumferential surface of the rotating drum 18 at positions that differ by a height corresponding to approximately 1/2 of the width W of the magnetic tape 16. As a result, although the details will be described later, the magnetic tape 16 is divided into two parts in the width direction.
Recorded information in two areas can be read simultaneously. Furthermore, in the illustrated embodiment, the magnetic heads 20a and 20b and the magnetic heads 22a and 22b are mounted at different positions on the rotating drum 18 by the track pitch Tp, but they are not at the same height. It's okay. [00111 FIG. 3 shows the track pattern of magnetic tape 16. The magnetic tape 16 is divided into two parts in the tape width direction, and the magnetic heads 20a and 2 shown in FIGS.
Each data track is formed by a magnetic head similar to 0b, 22a, and 22b. By recording with such a track pattern, recording and playback can be performed in the forward and reverse directions with a simple head configuration as shown in FIGS. 1 and 2 without turning over the tape cassette 10. become. [0012] In FIG. 3, ATF is the recording area for the pilot signal for ATF in the auto track finding method, PCM-R is the recording area for the PCM signal of the right (R) signal of stereo audio, and PCM-L is the recording area for the PCM signal of the right (R) signal of stereo audio. Recording area of PCM signal of audio left (L) signal,
SUB is a recording area for search sub-data. The black arrow indicates the head trace direction during recording, and the white arrow indicates the head trace direction during playback. Each signal is recorded in the order of ATF, PCM-R, SUB, PCM-L, and ATF as shown. For more information on data tracks,
“Electronics Life” edited by Japan Broadcasting Publishing Association 19
"rR-DAT Format" January 1986 issue P, 37-73. [0013] In high-speed search, only the SUB area needs to be reproduced, so for example, the magnetic tape 16 is wound around the rotating drum 18 with a small corner (for example, about 30').
to reduce the load on the magnetic tape 16,
Preferably, it allows for faster tape feeding. Figure 4
2 shows a plan view of the state in which the magnetic tape 16 is wound around the rotating drum 18. FIG. 30a, 30b; 32a, 32b
: 3.4a, 34b; 36a, 36b are movable posts that control the loading, that is, winding, of the magnetic tape 16 onto the rotating drum 18, and these movable posts are 30a, 32a, 34 when fully reproduced.
a, the magnetic tape 16 is wound around the rotary drum 18 at an angle of approximately 90 degrees by moving to the positions shown at 30b, 32b, 34b, and 36b, and winding the magnetic tape 16 around the rotating drum 18. Make the corners approximately 30°. [0014] FIG. 5 shows details of a data track and a timing diagram of its playback process. Guard spaces are provided between each area so that recording and reproduction can be performed for each area. For example, it is possible to perform so-called "dubbing" in which only one of the main data, PCM-R and PCM-L, is updated, and after recording music, it is possible to rewrite only the subcode area and find the beginning of the song. It is also possible to A preamble and a postamble are provided before and after each data area, and these parts perform PLL pull-in necessary to generate a clock that is an operation reference for digital processing of data detection. Figure 5 (1) shows details of the data track, Figure 5 (2) shows the search gate signal for extracting the SUB area, Figure 5 (3) shows the gate signal during forward search for PLL pull-in, and Figure 5 (4) shows the gate signal for searching in the forward direction for PLL pull-in. ) indicates the gate signal during backward search. [0015] Taking the subcode area as an example, the data detection operation when the magnetic head traces in the opposite direction to that during recording will be explained. Usually, the PL in the preamble is
After completing the pull-in of L, detect the data sink. A data sync is a digital synchronization signal that specifies the leading bit that determines when to start reading a data block. The data sink consists of a bit pattern of 10-odd bits to several tens of bits that appears very infrequently (or does not appear in the main data). After data sync, data and error correction data are recovered. [0016] FIG. 6 shows a block diagram of the configuration of the reproducing circuit system of this embodiment. The same components as shown in FIGS. 1 and 2 are given the same reference numerals. In this embodiment, the magnetic heads 20a, 22a and the magnetic heads 20b, 22b are attached to the rotating drum 18 facing each other at 180 degrees, and the magnetic tape 16 is wound around the rotating drum 18 at 90 degrees, so that the magnetic heads 20a, 22a and magnetic heads 20b, 22
b do not contact the magnetic tape 16 at the same time. Therefore, in this embodiment, the magnetic heads 20a, 20b and the magnetic head 2
The outputs of 2a and 22b are directly connected to each other and taken out from the rotating drum 18 via a common rotary transformer (not shown). (0017) In FIG. 6, 40 is the magnetic head 20a. 22a or the magnetic head 20b, a head selection switch that selects the output of 22b, 42.44 is a waveform that shapes the waveform degraded by the electromagnetic conversion system using the magnetic tape of the magnetic head. This is an equalization circuit. The waveform equalization circuits 42 and 44 are a type of filter circuit, and the waveform equalization circuit 42 has filter coefficients set that are optimized for reproduction in the same direction as when recording. The waveform equalization circuit 44 is set with filter coefficients optimized for reproduction in the opposite direction to that during recording. 46 is a switch for selecting the output of the waveform equalization circuit 42 or 44. [0018] 48 is an A/D converter that converts the output of the switch 46 into a digital signal, 50 is a memory that stores the output data of the A/D converter 48, and 52 is used to generate a write address and a read address for the memory 50. 54 is a synchronization extraction circuit that extracts the above-mentioned data sync from the data read from the memory 50; 56 is a correction interpolation circuit that corrects errors according to an error correction code and interpolates uncorrectable portions; 58 is a reproduction circuit; This is a clock generation circuit that generates a clock signal that serves as an operation reference. [0019] 60 is a drum system consisting of a motor that rotates the rotary drum 16 and a circuit that detects its rotation speed and phase. 62 is a drum system that runs the magnetic tape 16. A tape running system 64 consisting of a capstan etc. controls the drum system 60 and tape running system 62, and switches 40 and 46.
66 is a system control circuit that controls the entire system, and 68 is an operation key for inputting various instructions to the system control circuit 66.

The operation during the search shown in FIG. 6 will be explained with reference to the timing diagram shown in FIG. The servo circuit 64 is connected to the drum system 6
A drum rotation phase signal (FIG. 7(1)) having one rotation of the rotary drum 18 as one cycle is generated by a signal from a drum PG (phase detection signal generation circuit) of No. 0. The period “outward” and the period “return” are each half a cycle. Servo circuit 64
Also, during the "outward" period, the outgoing magnetic heads 20a, 2
2a, and select the output of the return magnetic heads 20b and 22b during the "return" period.
Controls 0. [00211 The reproduced signal selected by the switch 40 is waveform-equalized by the waveform equalization circuits 42 and 44. switch 4
6 is normally connected to the a-contact side that selects the output of the waveform equalization circuit 42, but during the search, the servo circuit 64 selects the "forward" period and "forward" period of the drum rotation phase signal in FIG. 7(1).
The a and b contacts are switched alternately depending on the recovery period. As a result, the playback signal from the outbound data area is
The waveform equalization circuit 42 optimally equalizes the waveform, the reproduced signal from the return data area is optimally waveform-equalized by the waveform equalization circuit 44, and the switch 46 outputs the optimally waveform-equalized signal. selected. [0022] The signal selected by the switch 46 is converted into a digital signal by the A/D converter 48 and sequentially written into the memory 48 according to the write address generated by the address circuit 52. The address circuit 52 includes the servo circuit 6
Referring to the time information from 4, an address signal for the memory 50 is generated to control writing and reading. magnetic head 2
Since the playback outputs of 0a, 22a, 20b, and 22b are sequentially supplied at 180° intervals, writing (W) to the memory 50 is performed at 90' in the first half of 180°, and reading (R) is performed at 90° in the latter half. Let's do it. The signal from the outbound data area is read out using the forward read address (the same count up as when writing) as shown in Figure 7 (3), while the signal from the return data area is read out at the forward read address (counted up in the same way as when writing), as shown in Figure 7 (3). ), the data is read using the read address (countdown) in the reverse direction. Thereby, the arrangement of the reproduced data from the return data area can be corrected in the forward direction. [0023] The data read out from the memory 50 in this manner is supplied to a synchronization extraction circuit 54 to detect a digital synchronization signal, and a correction/interpolation circuit 56 performs error correction and interpolation using a well-known method. [0024] PLL pull-in in the clock signal generation circuit will be briefly explained. When performing analog processing, the outgoing preamble and return postamble signals are extracted from the output signal of the switch 46 using the gate signals shown in FIGS. Apply to the oscillator and pull in the frequency and phase. In addition, when performing digitally, the outgoing and incoming preamble signals are taken out from the output of the memory 50 and pulled in. [0025] In the above embodiment, the conversion of the data sequence of the reproduced data from the backward path was realized by counting down the read address, but of course, the change in the write address is reversed, and the read address is changed from the reproduced data from the outward path. They may be changed in the same order. [0026]

As can be easily understood from the above description, according to the present invention, search data for both outbound and return trips can be simultaneously reproduced and output.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a rotary head system of the present invention.

FIG. 2 is a diagram showing the arrangement of heads on the circumferential surface of the rotating drum 18.

FIG. 3 is a data track pattern on a magnetic tape.

FIG. 4 is a plan view of the state in which the tape is wound around the rotating drum 18.

FIG. 5 is a data track configuration and timing diagram.

FIG. 6 is a schematic block diagram of a reproducing circuit.

7 is a timing diagram of the reproduction circuit of FIG. 6. FIG.

[Explanation of symbols]

10: Tape/cassette 12, 14: Reel 16:
Magnetic tape 18: Rotating drum 20a, 20b, 22
a, 22b: magnetic head 30a, 30b; 32a, 3
2b; 34a, 34b; 36a, 36b: Movable post 4
0: Head selection switch 42.44: Waveform equalization circuit 4
6: Switch 48: A/D converter 50: Memory 52 Near address circuit 54: Synchronous extraction circuit 56: Correction interpolation circuit 58: Clock generation circuit 60 Nidrum system 62: Tape running system 64: Servo circuit 66: System control circuit 68 :Operation key

[Figure 3]

[Figure 6]

Claims (3)

[Claims] 1. A playback device in a recording system that divides a tape-shaped recording medium into a plurality of areas in the tape width direction and records information in predetermined areas according to the tape running direction, comprising:
1. A reproducing device comprising a predetermined number of magnetic heads for reproducing in the same direction as when recording, and a predetermined number of magnetic heads for reproducing in the opposite direction to the direction during recording. 2. A first waveform equalization circuit that equalizes the waveform of a signal reproduced in the same direction as when recording, and a second waveform equalization circuit that equalizes the waveform of a signal that is reproduced in a direction opposite to that during recording. The reproducing device according to claim 1, further comprising a converting circuit. 3. The reproducing apparatus according to claim 1, wherein the sequence of data reproduced in a direction opposite to that at the time of recording is reversed by address control of the memory.