JPH01317253A - End searching method for digital audio tape recorder - Google Patents

Abstract

PURPOSE:To search the end of a tape including the recorded parts of the PCM signals and the blank parts regardless of the presence or absence of the end information recorded in a subcode area by detecting accurately the blank length longer than a prescribed time. CONSTITUTION:When the terminations of a series of recorded tapes are detected, the blank time is counted at and after the position of the blank head following a recorded part by a fast reproduction action (+25-fold speed). Then it is checked whether said blank time is equal to a 1st prescribed time, e.g., 8 seconds or not. When a blank equal to this prescribed time (8 seconds) is detected, the blank time is counted by a rewind reproduction (-1-fold speed) slower than the previous speed. Then it is checked whether this blank time is equal to a 2nd prescribed time, e.g., 9 seconds or not. Then a stop mode is set at the terminations of a series of recorded parts. Thus the end can be searched even for such a tape containing no end information on the PCM signal recorded in a subcode area.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a rotary head type digital audio tape recorder C (hereinafter referred to as R-DAT), and particularly to an end search method used when repeating.

(p) Regarding the conventional technology R-DAT, for example, as described on pages 1) to 66 of the March 1987 issue of the magazine "Electronics Life" (published by Japan Broadcasting Publishing Association), The magnetic tape is alternately helically scanned by a pair of rotary recording and reproducing heads with different azimuth angles, and each track of the tape is recorded with a PCM signal consisting of time-compressed audio data in a track format.
F (Automatic Track Findi)
ng) signal, and a tracking control signal called P
It is configured to record subcodes such as table of contents information and time information of a program related to a CM signal in a divided manner as in the format shown in FIG.

Problems to be solved by the "ej" invention By the way, currently in R-DAT, P
Although end information indicating the end of the recording area of the CM signal is recorded, there is a drawback that an end search using the end information cannot be performed on a tape on which the end information is not recorded.

2) Means to solve the problem When directing the end of a series of recorded tapes, start measuring the blank time from the beginning of the blank after the recorded part by fast forward playback operation, When a blank for only the first predetermined time is detected, the blank time is measured by rewinding and reproducing at a slower speed than the fast forward multiple reproducing operation. We propose an end search method for R-DAT that detects whether there is a blank for a second predetermined period of time and enters a stop mode at the end position of a series of recorded portions.

(E) Operation According to the above configuration, an end search can be performed on a tape having a PCM signal recording portion and a blank, regardless of the presence or absence of end information recorded in the subcode area.

(v) Example Next, Figures 1 to 5 show an example of the present invention.
This will be explained in detail with figures. In Figure 2, σ3 is an input terminal into which an analog signal is input, and ■ is an input terminal u3.
The PCM information recording processing circuit connected to the input terminal [141] performs PCM processing on the audio signal at the input terminal [141,
Audio PCM information to be recorded in area (5) is generated and output. (151 is an ATF signal generation circuit, which generates and outputs the ATF signal recorded in the ATF area (41, +61) in Fig. 6. αe is a subcode information generation circuit, which will be described later) The subcode information etc. are transferred from the subcode area !31.+71 in FIG. 6 and the subcode information is generated and output.

In is a timing circuit connected to the processing circuit and the generation circuit a input (161), and based on the reference clock of the reference clock generation circuit (not shown), the tape il of FIG.
+ Each PCM area (5) of each track (2)
and ATF area (4), (6), subcode area (31, +71 recording trace timing, processing circuit I PCM information and generation circuit (151, αe ATF
The signal and subcode information are digitally modulated and output to the recording amplifier (181).

Housing 9, ■ is a pair of rotary heads for recording and reproducing of azimuthal and reverse azimuth, which are installed at a position 180M apart from the periphery of the head cylinder (21), and the cylinder is based on a cylinder motor (not shown). Due to the rotation of 21), cylinder +21
) The tape (1) running with 90 wraps is alternately helically scanned, and during recording, amplified output signals are alternately supplied via a rotary transformer.

(2) is a reproduction amplifier connected to the head 1) 9 and (2) via a rotary transformer, and the reproduction signal from the head 19 (2) is inputted via a rotary transformer (22).

(24) is a PCM information reproduction processing circuit connected to the amplifier, which forms a timing signal for reproduction such as a PLL clock from the output signal of the amplifier, and based on the timing signal, is included in the output signal of the amplifier θ. The PCM information in the PCM area (5) is demodulated, subjected to error correction and interpolation processing, and converted to analog, and an analog reproduced audio signal is output to output terminal 4.

■ is the tracking servo circuit connected to the amplifier (231), and from the output signal of the amplifier to the ATF area (4)
, (6) are extracted, and an ATF error signal for tracking control corresponding to the level of the crosstalk component of the ATF signals from two adjacent tracks is formed and output.

The surface is a capstan motor drive circuit to which the ATF error signal is input, and when reproduction tracking is performed, the ATF error signal is used as a rotational phase control signal to drive and control the capstan motor (not shown). (to) to control the running phase of the tape (1) and control playback tracking.

I23 is a sub-code information reproduction processing circuit connected to the amplifier, which extracts the sub-code area +31. from the reproduced signal of the amplifier. +71 subcode information is demodulated, and the presence or absence of reproduction errors is detected by a parity check using the parity check code of parity area o1), and the subcode information in which no reproduction errors are detected is captured and will be described later. At the same time, the regeneration processing circuit U
41 is supplied with data necessary for reproduction processing such as sampling frequency data.

C25a) is an envelope detection circuit connected to the amplifier, which detects the presence or absence of an envelope and outputs it to a control circuit (to be described later).

The envelope detection circuit (23a) detects the envelope as shown in FIG. Figure 2 shows the switching pulse of head B).
) is an envelope with peaks and valleys formed by the azimuth loss caused by the rapid traverse 9. The control circuit (described later)
At 301, an envelope detect signal (see FIG. 4 (see 31)) which is shortened to the envelope is output. Also, FIG. 4 (4) shows the recording state of the tape (1).
1a) shows the recorded portion, (1b) shows the blank, and the arrows show the trajectories of the A head and B head during high-speed search.

(The sword is a control circuit that controls the entire device, and the device is controlled based on subcode information taken into the processing circuit, operation key signals from the key input terminal 31), and detection signals from the mechanism detection input terminal (to). It controls the operation mode, and controls the operation of the servo circuit 126+, cylinder motor drive circuit, reel motor drive circuit, etc., which will be described later, according to the operation mode, and at the time of after-recording, it uses subcode information from the processing circuit +291 and an internal timer. Together with the formed A time information and program time information (hereinafter referred to as P time information), the output signal of the envelope detection circuit (25a) is used to measure the blank time, and the time information etc. are sent to the generation circuit 1f9. Forward.

The cylinder motor drive circuit drives the cylinder motor based on the control of the control circuit ■ to drive the cylinder Q1).
drive the rotation. (to) is the reel motor drive circuit υ
, based on the control of the control circuit (301), the dedicated glue motors for the supply reel (to) and take-up reel (to) are driven to rotate, and the tape (1) is run in the forward or reverse direction of the arrow.

In addition, the amplifier (181SC3 and each drive circuit (271
, 田, and (to) are formed using a microcomputer or the like.

Next, the end search operation of the R-DAT device having the configuration shown in FIG. 2 will be explained with reference to the flowchart shown in FIG.

First, when the end search operation is designated by the key input terminal Ca1l, a series of recorded tapes with envelope waveforms such as (a) A7H in FIG. 5 are rewound to the starting end (step 1). Next, a fast-forward playback operation (step 2) is performed from the beginning of the tape, for example at about 25 times the speed. That is, the envelope detection circuit (25a) detects the envelope as shown in FIG. 4(2). Once we detect a blank area (step 3), we start measuring the blank length (step 4).
). Then, it is determined whether the blank length is a first predetermined time (for example, 8 seconds at normal speed) (
Step 5] and stop the tape (Step 6)
). However, if the blank length is less than the first predetermined time, the fast-forward playback operation (step 2) is connected.

However, in measuring the blank length during the fast-forward playback operation (step 2) at about 25 times the speed, an error occurs because tracking control cannot be performed accurately.

Assuming that the error is, for example, ±1 second, when the first predetermined time is determined in step 5, the blank length will actually be 7 to 9 seconds at normal speed. Therefore, from the stopped state (step 6), normal speed rewind playback operation (step 7) is performed.
The blank length measurement starts again (step 8), (step 9), and the blank length reaches the second predetermined time (step 9).
(e.g. 9 seconds at normal speed) or more (step 10)
), the envelope is detected during the rewind playback operation (step 1)), and the blank head position is regarded as the end of the recorded portion of the PCM signal, and the tape is stopped (step 12), and this end search operation is performed. end. An example of a timing chart of such an end search operation is shown in FIG. 5(b).

Therefore, the blank of the tape having a blank length longer than the second predetermined time can be accurately detected, and the leading position of the blank can be regarded as the end of the recorded portion, and the blank can be stopped at the leading position of the blank. From the stopped state (step 12), it is possible to smoothly transition to the recorded portion.

In addition, taking into consideration that the tape may overrun after determining that the first predetermined time has reached the first predetermined time during fast-forward playback at 25x speed, the length of the tape for measuring the second predetermined time is set to the blank start position. By making the second predetermined time longer, even more accurate end search becomes possible.

Further, step 15 is a step for preventing the operations of steps 2 to 10 from being repeated when it is determined that the blank length is the first predetermined time but less than the second predetermined time. This is a normal playback operation in which the tape is played back for a predetermined time after 10, and then the tape is sent.

(G) Effects of the Invention According to the present invention, when detecting the end of a series of recorded tapes, it is possible to accurately detect a blank length longer than a predetermined time. This is extremely useful as it allows smooth and accurate recording from one position to the next.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining the end search operation of the present invention, FIG. 2 is a diagram showing the seven-stem configuration of the device of the present invention, and FIG. 6 is a diagram showing the track format of a rotary head type digital audio tape recorder. Figure 4 (
1), (2), (3), (4) and Figure 5 (a), (
b) is a schematic diagram for explaining the operation of the present invention.

Claims (1)

[Claims] (1) A tracking area and a subcode area are formed together with the PCM area in each track of the tape that is helically scanned by a rotating head, and the PCM signal, which is the main signal, is recorded in the PCM area, and the tracking area is In a digital audio tape recorder where a tracking control signal is recorded and a subcode related to the main signal is recorded in the subcode area, when detecting the end of a series of recorded tapes, the recorded portion is Start measuring the blank time from the next blank head position, detect whether this blank exists for a first predetermined time, and when the blank for the first predetermined time is detected, the speed is slower than the fast forward playback operation. The rotary head type is characterized in that it measures the time of the blank by the rewinding and reproducing operation, detects whether the blank remains for a second predetermined time, and enters a stop mode at the end position of a series of recorded portions. End search method for digital audio tape recorder.