JPS59117745A - Reproducing device - Google Patents

Abstract

PURPOSE:To detect the difference in running speed and to enable-automatic change-over to the running speed for recording by using a detected output by detecting the period of the flactuation of the level of a reproduced output even if the signal indicating the running speed in the stage of recording on a magnetic medium is not recorded. CONSTITUTION:The tracks recorded with + azimuth and - azimuth are designated respectively as a0, a1-, b0, b1 when a tape recorded in a long time mode is going to be reproduced in a standard mode. The tape speed of the long time mode is made 1/2 that of the standard mode and the width of a record/playback head of the long time mode is made 1/2 the width of the playback head of the standard mode. The traces of the head of the standard mode are shown by broken lines, i.e., the tracing locus by the + azimuth head are designated as A1, A2 and the locus by the - azimuth head is designated as B1. Therefore the reproduced output reproduces the tracks a0 and a1 in the field A1, b2 in the field B1 and a2 and a3 in the field A2. The adjacent crosstalk components are detected in the fields A1, A2 and the level decreases as compared to the reproduced output in the field B1. The difference in the speed is detected by comparing the reproduced output with the prescribed threshold level.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a reproducing apparatus that reproduces information from a long recording medium recorded at at least two different running speeds.

Various playback devices can be considered as such a playback device, such as a magnetic recording center main device, an optical wagyu device, etc., but in this specification, a video tape that plays back video information from a magnetic tape on which a television signal is recorded is used.・Recorder (hereinafter referred to as VTR)
) will be explained as an example.

<Description of the Prior Art> In recent years, high-density magnetic recording has become possible, and VTRs have been developed and produced that enable long-time recording and playback by slowing down the running speed of the tape and narrowing the trunk pitch. I've been

These VTRs are configured with different time modes, such as standard time, long-time recording, and half-time recording, in order to be compatible with conventional formats. When playing back a magnetic tape recorded on a VTR with a time mode like this, it must be played back in the same time mode as when it was recorded, otherwise the playback image will be distorted because the time mode is different. Put it away. It would be very difficult for the user to manually switch the playback time mode while looking at the playback image. Conventionally, a control signal (hereinafter referred to as CTL48) is recorded at one frame interval at the edge of the tape during recording, and the output of a frequency generator detects the rotational speed of the capstan motor, which is proportional to the traveling distance of the magnetic tape during playback. By counting how many pulses are output during the CTL signal generation interval, the time mode is different between recording and mutual production1.
The playback time mode was automatically switched by detecting whether or not the playback was occurring.

Here, a description will be given based on this conventional example and the drawings. Figure 1 shows a conventional method of counting the F''G of a capstan motor from a CTL signal. In the figure, 1 is a magnetic tape, which is run in the direction of the arrow by a capstan 2 and a pinch roller 3. A rotating magnetic head (not shown) attached to a rotating drum records a video signal recorded obliquely to the longitudinal direction of the magnetic tape 1.
be born. The capstan 2 is rotated by a capstan motor 4 via a υ belt 5 at a constant speed.

6 is a frequency generator that detects the number of rotations of the capstan motor 4, and the number of output pulses and the running speed of the magnetic tape 1 are in a proportional relationship, and this signal is sent to the clock of the counter 8 via the amplifier 7. It is input to input terminal CK. On the other hand, a control head 9 reproduces the CTL signal recorded on the hoop 1 frame by frame, and inputs it to the reset terminal R of the counter 8 via an amplifier 10 and a waveform shaper 11. With the above input, the next CT from CTLi
The number of rotations of the capstan motor is counted in the CTL section up to the L signal, and the outputs Q, -Q4 are output to the magnitude comparator 13. On the other hand, the comparator 13 compares the output of the set standard setter 12, and when the output is greater or less than the reference set value, a high level is output to the output.

In other words, if the number of pulses input to the counter 8 in the CTL section in the standard mode is 44 pulses, then in the long mode where the recording time is doubled, the tape feeding speed will be halved.
The interval between CTLOs is 172 in the standard mode. Therefore, when a magnetic tape recorded in the long-time mode is reproduced in the standard mode, the number of pulses between CTLs is not the original 44 pulses, but only half that number, 22 pulses, is input. Therefore, set the standard setting value of 12 between these 22 and 44 pulses, and if the count is less than the set value when playing in standard mode, the recording mode will be set to long time mode.
When the set value is exceeded, the recording mode becomes the standard mode. However, if the CTL signal is missing or if Format 5, which does not record the control signal from the beginning during recording, is adopted, inconveniences arise.

<Object of the Invention: In view of the above points, the present invention provides a playback device that can detect that the running speed of a recording medium during recording is different from the running speed during playback even when a CTL signal is not recorded. is intended to provide.

<Description of Embodiment> FIGS. 2, 3, and 4 are principle diagrams for explaining this embodiment.

Figure 2 (a) is a diagram showing the recording trajectory on the magnetic tape.
o, al+... are tracks recorded with a plus azimuth recording head, bO1b+! . . . is a negative azimuth recording track, and is recorded in long-time mode. On the other hand, the playback mode is played back in standard mode, the tape running speed in long time mode is 1/2 that of standard mode, and the width of the recording/playback head in long time mode is the width of the playback head in standard mode. Set it to 1/2.

Therefore, the trace state of the head in the standard mode is traced as shown by the broken line. The trace loci are traced by the AI and Atu frus azimuth heads, and the trace loci are traced by the 1B+U minus azimuth heads.

Therefore, the playback output from each head is as shown in FIG. 2 (b). In the field, trunk a. and ao, BI field is 1, A is played, and atlas is played in field. That is, in the At and At fields, adjacent crosstalk components are detected.B.

The playback level is lower than the playback output of the field.

Therefore, by comparing the reproduced output with a predetermined threshold level S, a curve is obtained (comparison output shown in /→) in FIG. This pulse is obtained once every two fields.

FIG. 3 is an explanatory diagram when recording in standard mode and reproducing in long time mode. As shown in Figure 3 (a), a tape recorded azimuthally as tracks b, -a, -b, -a is played back with an azimuth playback head that has the same width as the recording head as A+ Br 4 Bt As Bs. do. A, same azimuth track a in the field,
, trunk b is played in the B field, track a is played in the A field, and the playback output level is the same as the slow playback of the fil/th conversion, as shown in Figure 3 (b). The waveform becomes 9 [by comparing with the fixed threshold value S, one pulse is obtained in 4 fields (
Figure 3 (]→).

In the fourth case, the width of the mutual azimuth head is 1/2 that of the recording head, and the width of the reciprocal azimuth head is 1/2 of that of the recording head.

When an azimuthally recorded track is reproduced with an azimuth head, as shown in FIG. 4(b), almost no reproduction output is obtained in the B+ and B- fields. Therefore, Figure 4 (c)
As shown in FIG. 3, a comparison output pulse is obtained once every four fields, and a noise bar is generated on the screen once every four fields, as in the case of the third T1 (c).

Of course, if the traveling speeds during recording and reproduction are the same, neither the comparison output pulse nor the noise bar is generated.

FIG. 5 is a diagram showing an embodiment of a detection circuit for detecting a difference in traveling speed. Hl is a positive azimuth head, H2 is a negative azimuth head, SW is a switching circuit for switching heads, 100 is an amplifier, 101 is an envelope detector, 102 is a comparator for comparison with a threshold level, 103 is a frequency-voltage conversion circuit, 104- 107 is a window comparator, ANDI, AND2 is an AND gate, R1-
R3 represents resistance.

Reproduction outputs from the heads H1 and H2 are amplified by an amplifier 100, and an envelope detector 101 obtains a reproduction envelope signal. The envelope signal is compared with a predetermined threshold value in the comparator 102 to obtain a periodic noise bar detection pulse as shown in FIG. The other input terminal of each comparator 104-107 receives a reference voltage obtained by dividing the power supply voltage VCC by resistors R5-R3. V, ~■4 are input respectively.Conversion circuit 10
3's output 'voltage' or V, if it is between ~■2, AND
When the output of the converter circuit 103 is between 1 and -V, the output of the converter circuit 103 becomes a high level. That is, when the noise bar is detected once every two fields, the output of the ANDQUETE ANIJ1 becomes high level, and it is detected that standard recording is being performed in long-time mode recording. And 1 in 4 fields
When the number of times is detected, the output of AND2 becomes high level, and it is detected that the standard mode recording is being performed for a long time.

This output is input to the sequence control circuit 108.

FIG. 6 is a diagram showing a part of the flow frame of the sequence control circuit 108.

First, the user's setting mode is read and it is determined whether it is standard mode or long-time mode. In the case of the standard mode, the tape is run in the standard mode, and it is detected whether the output of AND 1 is at the no/no level.

When the output of ANDl is at a low level, the reproduced video signal is output on the TV monitor. In the case of no-repel, run in long-term mode. Further, when the long time mode is set, the tape is run at a speed corresponding to the long time mode, and it is detected whether the output of AND2 is at the NO level.

When the output of AND2 is at a low level, the reproduced video signal is output as is on the TV monitor. In the case of no/no level, the tape is run in standard time mode. By doing this, a clear image without noise bars can be obtained on the TV monitor only when the playback mode is the same as that used during recording.

In this embodiment, a case has been described in which the ratio of the running speed of the recording medium during recording and during reproduction is 2:1 or 1:2, but the speed ratio can of course be detected in other cases as well.

The period of the detection pulse of the noise bar is detected by a frequency-voltage converter, but of course it can also be detected by a timer circuit or other means.

In addition, in this example, an example of a reproducing apparatus is explained using a device that reproduces an azimuthally recorded image. If the playback device deviates from the recording trajectory, the horse owner's output level will change, so by detecting the entire cycle, it is possible to adjust the horse owner's speed.

<Description of Effects> As explained above, according to the present invention, even if a signal indicating the running speed at the time of recording is not recorded on the recording medium,
By detecting the cycle of fluctuations in the reproduction output level, it becomes possible to detect differences in running speed. Furthermore, using the detection output, it is also possible to automatically switch to the traveling speed at the time of recording.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the prior art, and Figures 2 (a), (b), (
C) is an explanatory diagram when playing back a tape recorded in long-time mode in standard mode, Figure 3 (A), (C)
, Fig. 4 (a), (b), and (c) are explanatory diagrams when a tape recorded in the standard mode is played back in the long-time mode, and Fig. 5 shows the detection of the difference in running speed in this embodiment. The detection circuit diagram, FIG. 6, is a diagram showing a part of the program of the sequence control circuit of FIG. 5. In the figure, H1 and H2 indicate six raw heads, 101 an envelope detector, 102 a comparator, and 103 frequency-voltage converters, respectively. Procedural amendment (method) 1982 ■ April ↓ 9 [1 Director of the Japan Patent Office Kazuo Wakasugi 1 Indication of the case 1982 Patent application c 230445 1 2 Device for reproducing the name of the invention 3 Person making the amendment “11 I J1.
-2 Name (100) Canon Co., Ltd. Location 1℃146 3-30-2 F Maruko, Ota-ku, Higashi City
'Xeno/4;1. Inside the ceremony i'1 (telephone 75
8-2111) Name (6987) Patent Attorney Iiyoshi Marumi'
7"袢;H3; 2 (Regulation 5, Daily publication of the amendment order June 29, 1982 (shipment date) 6 Subject of amendment #1 No. Figure 2, Figure 6, Figure 4
The explanation of the figure has been corrected as follows. [Figure 2 is an explanatory diagram when a tape recorded in long-time mode is played back in standard mode, Figure 6. Figure 4 is an explanatory diagram when playing back a tape recorded in standard mode in long-time mode.]

Claims (1)

[Claims] By comprising a reproducing means for reproducing information from a long recording medium recorded at at least two different running speeds, and a detecting means for detecting a period in which the reproduction output level of the reproducing means changes, A reproducing device characterized in that it can detect when the running speed at the time is different from the running speed at the time of recording.