JPH06302061A - Tape speed measuring method - Google Patents

Abstract

PURPOSE:To easily and surely disriminate normal/defective condition of a reference tape by recording a reference signal while interrupting it for a prescribed time of period synchronizing with the revolution of a rotary drum and calculating a tape speed while measuring the distance between the interrupted parts on adjacent tracks. CONSTITUTION:Markers Sm which are obtained by passing pulses generated from a pulse generator 16 and synchronized with the revolution of the rotary drum through a wave forming unit 16 are supplied to a gate circuit 17 as gate pulses. In this way, the output of the circuit 17 becomes an intermittent reference signal So since a reference signal Sr in which pilot signals P are superposed is interrupted during only a period when markers Sm are obtained. The signal So is recorded in a reference tape 1 via a recording amplifier 18 and a head 19. Recorded patterns are visualized by developing the tape 1 and then specified calculations are performed by measuring the distance (i) between points X1, X2 actually. Thus, a recording speed and a track tilt angle are calculated and then the normal or defection of the tape 1 is discriminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape speed measuring method suitable for application to so-called 8 mm video.

[0002]

2. Description of the Related Art In order to allow a magnetic tape as a recording medium to be used interchangeably between VTRs, the inclination angle of a video track recorded on the magnetic tape with respect to the magnetic tape and the linearity of the video track must be controlled. It must be adjusted at the factory stage so that it falls within the standard value range. A reference tape for adjustment is required during such adjustment work.

That is, using this standard tape, it is judged from the reproduction output level that the head is correctly scanning the video track on the standard tape, and when mistracking occurs, on the tape path such as a tape guide. The member located at is adjusted.

Conventionally, a standard tape as shown in FIG. 4 has been used as a standard tape used for such a purpose.

In the figure, reference numeral 1 is a magnetic tape on which a helical video track 2 is recorded at a predetermined position.
In addition, the control signal CTL runs parallel to the longitudinal direction of the tape.
Is recorded. The recording inclination angle θ of the video track 2 is set within the standard value range, and the recording interval of the control signal CTL is also the interval at the standard tape speed. Such a standard tape 1
Is used to measure data for tape path adjustment as described above.

[0006]

By the way, in the standard tape 1 as shown in FIG. 4, a control signal is recorded on the tape together with a video signal, and the control signal C is reproduced at the time of reproduction.
Since it is a standard tape for VTR which measures the tape speed by reproducing TL, it cannot be applied as a standard tape of a device such as 8 mm video mentioned above.

It is not such a format that a control signal is recorded in such an 8 mm video and used for tape speed control during reproduction, and thus tracking control during reproduction, rather than the frequency along with the video signal on the video track. This is because the tracking adjustment (Automatic Track Following, that is, ATF adjustment) at the time of reproduction is performed by recording different pilot signals and reproducing the pilot signals.

By the way, whether or not the inclination angle of the video track and the linearity of the video track recorded on the standard tape 1 are within the standard values is determined by developing the tape 1 after recording the signal. The deviation from the standard value is calculated from the data obtained by measuring the recording interval of the control signal CTL recorded on the tape 1, and it is judged whether or not the deviation is within the standard. If the tape does not meet the standard value, the tape is not used as a standard tape.

On the other hand, since the standard tape 1 is prepared by using the standard tape preparing apparatus composed of the VTR of the same standard as the VTR to be adjusted, the standard tape prepared by the standard tape preparing apparatus for 8 mm video. Control signal C
No information signal for tape speed measurement corresponding to TL is recorded. Therefore, there is no way to confirm whether the standard tape created by the standard tape creating apparatus has a value that satisfies the standard value.

In view of the above, the present invention solves the above-mentioned conventional problems. For a standard tape in a device such as an 8 mm video, the tape speed information required when the standard tape is produced is recorded in the machine of the device. It proposes a tape speed measuring method that can be inserted without changing the physical structure.

[0011]

In order to solve the above problems, according to the present invention, as shown in FIG. 3, a reference signal to be recorded on the tape as a track inclined with respect to the longitudinal direction of the tape is rotated. The tape speed during signal recording is calculated by recording by blocking with a mark signal synchronized with the rotation of the drum for a predetermined period of time T, and measuring the distance to a blocking portion on an adjacent track. .

In this example, the reference signal Sr is gated by the marker Sm generated by the circuit shown in FIG. 1, and the gated reference signal Sr is recorded on the tape 1.

[0013]

When the marker Sm is superimposed and recorded on the reference signal Sr in this way, the recording pattern has a cutoff portion as shown in FIG. 3, and therefore the quality of the reference tape 1 is judged. By measuring the distance of the insertion position of the marker Sm in the tape longitudinal direction, the recording speed can be calculated, and the inclination angle θ of the video track with respect to the tape and the like can be easily calculated. Can be determined easily and reliably.

[0014]

1 is a system diagram showing an example of a standard tape signal forming circuit 10 to which a tape speed measuring method according to the present invention is applied, and 11 is a standard signal S shown in FIG. 2C.
r oscillator, the frequency of which is selected to be 1.5 MHz in this example. The value of this frequency is an example, and may be any frequency that can be recorded by the head 19 described later. on the other hand,
Reference numeral 12 is an oscillator of a pilot signal Sp (not shown) for tracking during reproduction. As the pilot signal Sp, four kinds of pilot signals having different frequencies are used. As is well known, four video tracks are provided. The pilot signals which are different from each other are sequentially recorded alternately. A standardized frequency is used for each frequency. The reference signal Sr and the pilot signal Sp are combined by the combiner 13 and then supplied to the gate circuit 17.

Reference numeral 15 denotes a pulse generator, which is provided in association with a rotating drum (not shown) as is well known, and a stable pulse (vertical synchronizing frequency f _V obtained in synchronization with the rotation of the rotating drum) is provided. ) Is waveform-shaped by the waveform shaper 16 (FIG. 2B), and this marker (its pulse width is several milliseconds) Sm
Is supplied to the gate circuit 17 as a gate pulse. As a result, the reference signal Sr on which the pilot signal Sp is superimposed is cut off only during the period T in which the marker Sm is obtained, so that the gate circuit 17 outputs an intermittent reference signal (hereinafter referred to as a recording signal) So as shown in FIG. 2D. Becomes The recording signal So is supplied to the head 19 via the recording amplifier 18. As a result, the tape pattern becomes that shown in FIG. The pattern shown is for the SP mode. Therefore, at least the reference signal Sr, the pilot signal Sp, and the marker Sm described above are recorded on the reference tape 1. Since the marker Sm acts as a gate pulse, the marker Sm is not actually recorded.

In order to judge the quality of the standard tape 1 thus formed, the standard tape 1 is developed so that the recording pattern can be visually observed, and then the standard signal Sr becomes discontinuous, for example. The tape speed V at the time of signal recording is calculated by actually measuring X ₁ , X ₂ and the distance i in the tape longitudinal direction on the tape and substituting the measured values into the following equation. _{V = (X n -X n-} 1) f v [mm / sec]

If the tape speed is calculated, the tilt angle θ of the video track 2 recorded on the tape can be obtained from this, and it can be determined whether or not the tilt angle θ is within the standard value. If it is not within the specified value, the tape is not used as a standard tape.

Further, the linearity of the recorded video track 2 is measured by a well-known CTL transversal linearity measuring method (see, for example, Japanese Patent Laid-Open No. Sho 5).
9-14102), and in this case, the linearity is obtained by determining the edge point (data in the Y direction) of the video track 2 in the tape width direction and determining whether or not the value falls within the standard value. The quality of can be determined. Both the tilt angle and the linearity of the video track are determined by computer.

Incidentally, as in the conventional case, the control signal CT
The measurement error between the case of measuring the tape speed using L and the case of measuring the tape speed using the marker Sm as described above is 0.01
It is obvious that even if the marker Sm is used, it can be used as a standard tape since it is only about%.

In the above, an example in which the reference tape 1 is created by recording the recording signal So continuously on each video track 2 has been described, but several video tracks are recorded continuously. Alternatively, the tape recorded intermittently at a predetermined interval may be used as a standard tape.

Further, in the above description, the inclination angle of the video track 2 and its linearity were obtained by computer processing after actually measuring the detection of the tape speed information, but a program for automatically processing all of these processing should be set up. In this case, the processing and the quality judgment of the standard tape can be fully automated.

[0022]

As described above, according to the present invention, as the standard tape 1 used for tape path adjustment of 8 mm video or the like, as shown in FIG. 3, a predetermined mark signal Sm synchronized with the rotation of the rotary drum is used. Since the reference signal Sr recorded for a period of time is recorded, the tape speed information at the time of recording can be easily obtained by detecting the recording interval of the marker Sm. Therefore, it is possible to surely determine the inclination angle of the video track 2 and the linearity of the video track 2 recorded on the tape from the tape speed information, and it is possible to accurately judge whether the standard tape is good or bad.

Of course, the error in the tape speed information when the control signal CTL is used is very small and can be neglected in practical use, and is no different from the conventional case.

Further, according to the present invention, the standard tape producing apparatus having the same standard as that of the 8 mm video is installed without any structural change (in the 8 mm video, a recording head capable of recording the control signal CTL or the like on the cue track is mounted. However, this is only recognized as an option, and this recording head is not normally provided.) It is convenient for practical use because it is possible to configure an appropriate standard tape making device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a circuit for forming a signal recorded on a standard tape to which a recording method of the present invention is applied.

FIG. 2 is a waveform diagram for explaining the operation of FIG.

FIG. 3 is a diagram of a track pattern showing an example of a standard tape to which the recording method of the present invention is applied.

FIG. 4 is a diagram showing an example of a conventional standard tape.

[Explanation of symbols]

 11 Oscillator of Reference Signal Sr 12 Oscillator of Pilot Signal Sp 15 Pulse Generator 17 Gate Circuit 19 Recording / Reproducing Head Sm Gate Pulse Functioning as Marker

Claims (1)

[Claims] 1. A reference signal to be recorded on the tape as a track inclined with respect to the longitudinal direction of the tape is interrupted and recorded for a predetermined period by a mark signal synchronized with the rotation of a rotary drum, and interrupted on an adjacent track. A tape speed measurement method that calculates the tape speed during signal recording by measuring the distance to the part.