JPH0246501A - Magnetic tape for adjusting tape travelling and method for inspecting and adjusting tape travelling - Google Patents

Abstract

PURPOSE:To attain the correct adjustment and inspection by recording a first FM signal to one side of a recording track, and recording a second FM signal frequency-modulated by the video signal of the different level to the other side recording track. CONSTITUTION:At one side of two adjoining inclination recording tracks out of respective inclination recording tracks of a magnetic tape, a first FM signal with a first video signal composed of a composite synchronizing signal and a signal BL and a marker as a modulating signal is recorded. At the other side inclination recording track, a second FM signal with a second video signal composed of a composite synchronizing signal, a signal BH and a marker as a modulating signal is recorded. Namely, since the signal of the adjoining track has a prescribed level difference, first and second FM signal frequencies are different. Consequently, when a tracking dislocation occurs and a reproducing FM signal and a crosstalk component are added, the fluctuation of the envelope of a reproducing FM signal after adding hardly occurs. Thus, the envelope of first and second FM signals is made easy-to-see and the adjustment and inspection of the linearity of the track are executed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic tape for tape running adjustment and a tape running adjustment inspection method, and particularly to magnetic tapes used for adjusting track linearity, switching points, etc. Concerning adjustment inspection method.

In the adjustment inspection of the tape running system in a conventional helical scan type magnetic recording/reproducing device (VTR), the I
As shown in the figure, the monoscope signal at 100% white level (or the gray scale signal that changes stepwise from black level to 100% white level) is output with an FM carrier frequency of 3.4MH2 at the sync chip level and a white level of 10.
Frequency modulation (F
First, an inspection tape (test tape) on which the FM signal having the frequency spectrum shown in FIG. 8(A) obtained by performing step M) is recorded in advance at a predetermined level is played back. If this reproduced FM signal is a monoscope signal, the main component is <4.4 MHz, as shown in FIG. 8(C), and if it is a gray scale signal, the main component is 3.7 MHz to 4.4 Htlz.

Conventionally, the FM signal reproduced from this test tape (the waveform is shown by ■ in Figure 8 (B)) was displayed and measured using an oscilloscope, and its envelope level was measured to check and adjust the linearity of the track. , the image after FM demodulation was used to check whether the switching point (switching point of the rotary head) was within the allowable range defined by the standard.

Problems to be Solved by the Invention However, the frequency of the FM signals recorded on the above-mentioned inspection tapes is relatively high and there is little residual magnetism, so they become unusable after about 5 days per tape due to demagnetization during the production process. .

In addition, the recording/reproducing frequency characteristics of the VTR to be inspected are as shown in Figure 9, and since the level of the FM signal reproduced from the above-mentioned inspection tape decreases according to the frequency characteristics shown in Figure 9, the low frequency Horizontal synchronization signal (H-8YNC)
As shown by black circles in FIG. 8(B), the parts remain in the shape of whiskers and are hard to see, and since the frequency characteristics shown in FIG. 9 differ depending on the model, the lengths of the whiskers also vary. For this reason, various measurements such as flatness obtained from the difference between the upper and lower envelopes of the reproduced FM signal are inaccurate because the envelopes cannot be accurately identified due to the whiskers, making it difficult to improve the adjustment accuracy and causing erroneous judgments. Was.

In addition, when adjusting the linearity of a VTR, crosstalk between the two rotating heads that record and play back adjacent tracks causes the level of the reproduced FM signal to fluctuate, making it difficult to see the envelope, resulting in erroneous adjustments and misjudgments. Was.

Furthermore, when inspecting the switching point adjustment, there are no marks on the waveform and it is necessary to count the horizontal synchronizing signals, which may result in incorrect adjustment or misjudgment due to a counting error.

In addition, in jitter and slobber noise checks that are performed by looking at the playback screen, the background screen is also entirely white compared to the white inspection points, which can lead to false judgments for VTRs that are close to the specifications, and the equipment is expensive. There were problems such as:

The present invention has been made in view of the above points, and it is an object of the present invention to provide a magnetic tape for tape running adjustment and a tape running adjustment inspection method that enable accurate adjustment and inspection with a long life.

Means for Solving the Problems The magnetic tape for tape running adjustment according to the present invention has two adjacent magnetic tapes.
A first FM signal frequency-modulated with a first level video signal is recorded on one of the recording tracks of the book, and a second FM signal whose frequency is modulated by a video signal of the first level is recorded on the other recording track.
This is a recording of a second FM signal frequency-modulated with a video signal at a level of You can.

Further, the tape running adjustment inspection method of the present invention reproduces the recorded green signal of the magnetic tape for tape running adjustment in the magnetic recording/reproducing device to be adjusted, and at least the envelope of the green signal and the reproduced signal after FM demodulation are reproduced. The tape running system of the magnetic recording/reproducing device is adjusted based on one of the two.

Furthermore, the tape running adjustment inspection method according to the present invention alternately supplies the above-mentioned first and second level video signals to the magnetic recording/reproducing device to be inspected for each track scanning period to cause the magnetic recording/reproducing device to record and reproduce. The tape running system is inspected based on at least one of the reproduced FM signal and the reproduced signal after FM demodulation.

Function The tape of the present invention improves demagnetization and also improves playback FM video signal (
The purpose of this is to significantly reduce the unevenness of the envelope of the first FM signal and the second FM signal. Here, as shown in Figure 7, the characteristic factors of demagnetization include: ■recording signal, ■tape tension, ■test tape,
■Video head (rotating head), ■Magnetized, etc. Of these, for recording signals, lowering the FM frequency component within the allowable range increases the bias current of the rotary head and increases the residual magnetic flux on the tape, which is effective against demagnetization. However, since the recording FM signal level is determined by the VTR standard, it cannot be changed.

Further, the demagnetization caused by the tape tension has little effect on the overall demagnetization, and no improvement effect can be expected. Furthermore, regarding the demagnetization caused by the test tape, the 111 degrees of demagnetization caused by the components of the magnetic powder is large, but since this type of research is in a different field, it is thought that it will take time to respond. Furthermore, demagnetization by the video head has a large effect on things other than compatibility adjustment such as image quality, and it also involves the accuracy of the head and drum, making it complicated to deal with. Furthermore, with regard to magnetization, the cause of magnetization due to the adhesion of magnetic powder is significant, and demagnetization due to adhesion to the head window is particularly noteworthy, but this will not be discussed here.

In view of the above points, the present invention improves the demagnetization effect by improving the recording signal frequency. That is, since the recording signal used in the present invention is not a signal from the white 100% level or from the black level to the white 100% level, but is a signal near the black level, the first. The frequency band of the second FM signal is located on the lower side compared to the FM signal band of the conventional monoscope signal or gray scale signal, and its bandwidth is also narrower to about ⅓.

In the magnetic recording and reproducing apparatus having the recording and reproducing frequency characteristics shown in FIG. 9, the recording frequency is lower than that of the conventional device, and a large amount of recording current flows, so that the residual magnetism on the tape increases. Therefore, the magnetic tape of the present invention, which has a large amount of residual magnetism, has the effect of improving demagnetization, and according to the experimental results of the present inventor, the amount of demagnetization of the magnetic tape of the present invention is about 1/2 of that of the monoscope signal recording tape. One thing was confirmed.

Also, the envelope whiskers of the reproduced FM signal are white 1.
This is caused by the FM level of the 00% portion decreasing due to the frequency characteristics shown in Figure 9, but in the present invention, the FM level is almost black and there is almost no decrease, so the reproduced FM signal has no whiskers and is easy to see. was also confirmed by experiment.

By the way, when the black level video signal described in -F is frequency-modulated and azimuthally recorded and reproduced on a magnetic tape, the FM signal frequency is relatively low and the azimuth loss effect cannot be expected sufficiently, and if tracking deviation occurs, the adjacent Crosstalk from the track is not sufficiently attenuated and is amplified with the reproduced FM signal of the reproduced track, and since the crosstalk and the reproduced FM signal have the same frequency, the reproduced FM signal is proportional to the phase difference and level difference between them. The envelope of the signal varies and cannot be used for linearity adjustment.

However, in the present invention, since the signals of adjacent tracks are all near the black level and have a predetermined level difference, the first. Since the second FM signal frequency is different, 1
- Even if the reproduced FM signal and the crosstalk component are added when a racking shift occurs, the envelope of the reproduced FM signal after the addition hardly changes. Therefore, the envelopes of the first and second FM signals are easy to see, and the linearity of the track can be adjusted and inspected with high precision.

Further, since markers indicating the permissible range and center position of the switching point 1 are added to each of the first and second level video signals, the position can be determined at a glance from the playback screen.

Furthermore, since the amplitude of the reproduced FM signal obtained by reproducing the above-mentioned magnetic tape for tape running adjustment with a magnetic recording and reproducing device can be roughly expressed as 1 to rack adjustment area of the video head,
The linearity of the track can be adjusted by its amplitude.

Further, by FM demodulating the above reproduced FM signal and supplying it to the oscilloscope together with the drum pulse, it is possible to know the head switching points 1 to 1, thereby making it possible to adjust the switching points.

Furthermore, by using the same tape running adjustment magnetic tape, the above adjustment can be performed under the same conditions for all magnetic recording and reproducing devices to be adjusted. Furthermore, various tests are performed based on a signal that is the same as the signal recorded on the above-mentioned magnetic tape for tape running adjustment and is recorded and played back by the magnetic recording/playback device to be tested. As a result, it is possible to inspect the linearity of the magnetic recording/reproducing device on each side to be inspected, the position of the switching point, and the like.

Embodiment FIG. 1 shows an explanatory diagram of an embodiment of a test signal recorded on the magnetic tape for tape running adjustment of the present invention and used in the method of the present invention. The magnetic tape for tape running adjustment in this example is obtained by frequency modulating the carrier wave with the signal shown in Fig. 1 (B), and the frequency spectrum shown in Fig. 1 (A) is multiplied by M. The signal is recorded by a rotary head in units of one field at an inclination of 1 to 100 degrees.

The test signals shown in Figure 1(B) are vertical synchronization signals (V-8YNC) such as Vl and V2, horizontal synchronization signals (not shown) and This is a video signal consisting of a signal BL near the black level or H higher than t, and the above signals B+- and BH are synthesized in time series with horizontal and vertical synchronizing signals alternately every 1 no yield. , the signal BL is at a low level near the black level 7
When terminated with 5Ω, the voltage is 0.03 V, and the signal BH is at a high level near the black level, and is 0.065 V. Further, the peak values of the horizontal and vertical synchronizing signals are 0.3V.

In addition, in this embodiment, as shown in FIG. 2, the high level marker Mo ( In addition, low-level markers M+, M2 (or M+-, M2 -) are superimposed on each other. Marker Mo,
Mo- indicates the normal switching point position, and the range between M1 (M+-) and M2 (M2-) indicates the switching point tolerance range.

In FIG. 2, solid lines Mo, M+, and M2 indicate markers for odd fields, and broken lines Mo-, tVI+M2- indicate markers for even fields. Further, B14 or BL indicates a signal near the black level described above, and 1-1°S indicates a horizontal synchronizing signal.

The test signals shown in FIGS. 1(B) and 2 having such a configuration are obtained by frequency modulating the carrier wave, and as shown in FIG. 1(A), the synchronizing signal tip level is 3.4 MHz, and the signal B L
Te 3.730 M l-l 'l, signal B l-1 Te 3
, 765 MHz into an FM signal with a carrier frequency of 765 MHz. The regular FM carrier frequency for the black level of the video signal recorded and played back on the VTR to be inspected is 3.70MH.
It is 7. Note that, among the above-mentioned frequencies, the frequency component is excluded.

When this FM signal (inspection signal@) is analyzed with a spectrum analyzer, as shown in FIG. 1(C), the main component is a frequency component around 3.7MH7.

In this embodiment, among each inclined recording track of the magnetic tape,
A first FM signal whose modulation signal is a first video signal consisting of a composite synchronization signal, a signal BL, and a marker is recorded on one of the 62 adjacent inclined recording tracks.
A second FM signal whose modulation signal is a second video signal composed of a composite synchronization signal, a signal BH, and a marker is recorded on the rack.

As a result, a magnetic tape for adjusting tape running of a VTR is created.

Next, a configuration of an embodiment of a test signal generator recorded on the above magnetic tape for tape running adjustment and an embodiment of a tape running adjustment testing method will be described. FIG. 3 is a block diagram of an embodiment of the signal generator described above, and FIGS. 4 and 5 are block diagrams of an embodiment of the main part of FIG. 3, respectively.

83 in FIG. 3, 1 is a signal generator, and a video oscillation unit 2.1k l-1z generates a test signal of the specific waveform.
3. Audio oscillation unit that generates a sine wave of ~9kl-1z as an audio signal. Control unit consisting of a microcomputer 4. It consists of a power supply unit 5, etc., and also connects an external controller etc. via a connector 6 to the G P-I B (G
eneral p urposeInterfac
e 13 us) interface, is connected to a jig etc. via a parallel l10 (Pro) via a connector 7, and is further connected to a VTR l0 via terminals 8 and 9. The controllers 1 to 1 connected to the GP-IB interface above control the television system (N
TSC system, PAL system), audio signal frequency, etc. are performed.

The video oscillator 2 has a configuration as shown in FIG.

A line signal (L I
NE) and the vertical synchronization signal are supplied to the switching point (SW, P) marker correction circuit 13, and the vertical synchronization signal and the horizontal synchronization signal are supplied to the SW, P marker oscillation circuit 14.

Further, the video oscillation IC 12 oscillates and outputs a black level signal and a composite synchronization signal (SYNC), of which the black level signal is amplified by an amplifier 15 and then passed through resistors 16 and 17 in parallel to a terminal of a switch circuit 18. 18a and 18b, respectively. Here, the resistors 16 and 17 are set to different predetermined values, the signal BL close to the black level is supplied to the terminal 18a, and the signal B1-4 close to the black level is supplied to the terminal 18b. . Also, sw, p
The markers Mo, M+ and M2 shown in FIG. 2 are supplied from the power oscillation circuit 14 to the terminal 18a, and the markers Mo-, M+- and M2- are supplied to the terminal 18b.

The switch circuit 18 has a configuration as shown in FIG. 5, which will be described later.
Switching is controlled by the output signal of the w and p marker correction circuit 13, and the terminals 18a and 18 are alternately connected every field.
Selectively output each input signal of b. The output signal of the switch circuit 18 is mixed with the composite synchronization signal by the resistor 19.20, and then passed through the buffer amplifier 21 to the 750 (
One is output via terminal 8 to the VTR.
The DC level of the other one is checked by the comparator circuit 22 and then supplied to the control unit 4 via the terminal 23, so that self-diagnosis is always performed.

Next, the configuration and operation of one embodiment of the switching point (SW, P) marker correction circuit 13 are shown in FIGS. 5 and 6.
This will be explained in more detail with reference to the drawings. Here, the marker may be shifted by 1H depending on the timing when the power is turned on. This is because the number of horizontal synchronizing signals for each field changes from 262/263 depending on the timing, so the difference of 11'' appears as a shift. Therefore, in this embodiment, the SW and P marker correction circuit 13 shown in FIG. This is to correct the position.

In FIG. 5, the vertical synchronizing signal and line signal taken out from the video oscillation IC 12 are phase-inverted by inverters 25 and 26. The above vertical synchronization signal is
Assuming that the signal is indicated by a in the figure, the output signal of the inverter 25 is as shown by a in FIG. 6, and this signal a is supplied to a monostable multivibrator (hereinafter referred to as MM) 27,
While this is triggered on its rising edge, it is also supplied to MM28, which is triggered on its rising edge.

As a result, from the Q output terminal of MM27, a pulse with a constant width of positive polarity as shown by b in FIG.
A pulse with a constant width of negative polarity as shown in is extracted at one field period.

On the other hand, 29 and 30 are flip-flops on J-, respectively.
The above-mentioned pulse b is applied to each of these J terminals, and the terminals are fixed at L I+ level, and the above-mentioned pulse d is applied to each of these clear terminals so that they are cleared at the falling edge of the terminal. It is connected to the.

In addition, the J- flip 70 knob 29 receives the line signal indicated by C in FIG. 6 applied to its trigger terminal via the inverters 26 and 31, respectively.
A line signal C inverted by an inverter 26 is applied to its trigger terminal. Flip knob 2 to J-
Both river power signals 9 and 30 are supplied to an AND circuit 32,
Here, a logical product is performed and a signal as shown by e in FIG. 6 is taken out. This signal e is the switch circuit 1
8 as a switching signal.

As can be seen from Fig. 6, this signal e is a 2-field period pulse with a 2631'' period of U L I+ level and a 262 day period of ''F1'' level, and the rising and falling points within 1H of the line signal C. This is the signal that was detected.

The explanation will be given by returning to FIG. 3 again. The test signals as shown in FIGS. 1(B) and 2 generated and outputted from the video oscillator 2 in this way are supplied to the VTR 10 together with the audio signal through the terminal 8, where they are frequency modulated. The signal is then converted into an FM signal having a frequency spectrum as shown in FIG. 1(A), and then recorded on a magnetic tape by a rotating head to create a magnetic tape for tape running adjustment.

Next, an adjustment method using this tape running adjustment magnetic tape will be explained. The magnetic tape for tape running adjustment is reproduced by the VTR to be adjusted, and the reproduced FM inspection signal is supplied to the oscilloscope.

As a result, the amplitude of the reproduced FM test signal is measured on the oscilloscope, and the amplitude is adjusted so that it is within a predetermined tolerance range.
Adjust the mechanical position of the guide [1-ra. The better the linearity of the track, the higher the level of the amplitude, and this amplitude changes depending on the mechanical position of the guide roller, so the linearity of the track can be adjusted by the adjustment described above.

When adjusting the track linearity, there are no irregularities in the envelope of the reproduced FM test signal, and no level fluctuations occur, so erroneous adjustments and erroneous judgments are reduced, and quality can be improved.

On the other hand, when adjusting the switching point, the reproduced FM test signal is FM demodulated and then supplied to the oscilloscope. This oscilloscope is supplied with a drum pulse that inverts every field in synchronization with the rotational phase of the rotating head of the VTR, and the trigger point indicating the drum pulse position on the DC mode screen of the oscilloscope is set at the marker Mo. (or Mo'), adjust the time constant of the monostable multivibrator for tracking preset adjustment of the head servo system of the VTR. When adjusting the switching point, the markers Mo, Mo', etc. mentioned above are displayed, so that erroneous adjustment and erroneous judgment due to erroneous counting of horizontal synchronizing signals can be reduced.

The above-mentioned track linearity and switching point adjustments for all VTRs to be adjusted are performed using the same tape running adjustment magnetic tape. As a result, since the reference test signals are the same, compatibility adjustment can be made and the number of types of test tapes can be reduced.

After the above adjustments are completed, various tests are performed. During this test, the 1:M test signal generated by the signal generator 1 shown in FIG. 3 is supplied to the VTR to be tested, and this VTR performs self-recording/playback. During this test, check whether the amplitude of the reproduced FM test signal is within the allowable range.
Also, use an oscilloscope to check whether the switching points (the rising and falling edges of the drum pulse) are within the upper and lower limit markers. In this switching point inspection process, there is no need to count the number of horizontal synchronization signals, so the inspection time can be shortened.

In addition, in a VTR that records FM audio signals using a rotating head, when performing a tracking phase shift check, the envelopes of the FM audio signal and FM video signal are simultaneously played back and inspected, but the influence of the FM video signal is Since it does not appear in the signal envelope, false judgments can be reduced compared to conventional methods.

In addition, in jitter and slobber noise checks, in which the reproduced FM inspection signal is FM demodulated and displayed on a monitor receiver, and the inspection is performed by looking at the playback screen, the background is black compared to the white inspection point, so the spec. Misjudgment can be reduced even if there is a nearby VTR.

Note that the switching point marker does not necessarily have to be provided.

Effects of the Invention As described above, the present invention has the following features.

■The amount of demagnetization of the adjustment magnetic tape (test tape) is less than half that of conventional monoscope signal or grayscale signal recording tape, so the usable period is more than doubled, resulting in significant cost savings. can do.

■During track linearity adjustment and inspection, the envelope of the reproduced FM inspection signal is not affected by crosstalk, there are no uneven whiskers, and there are no level fluctuations, improving adjustment inspection accuracy. .

- Markers for switching point adjustment can reduce switching point misadjustments and misjudgments, as well as shorten inspection time.

(2) When performing a tracking phase shift check on a VTR that records and reproduces FM audio signals using a rotating head, the influence of the reproduced FM video signal does not appear on the envelope of the reproduced FM audio signal, making it easy to see and reducing erroneous judgments.

- When the FM demodulation test signal is set near the black level, the background of the playback screen becomes black, so the white test points are easy to see in jitter slobber noise checks, etc., and erroneous judgments can be reduced even with VTRs near the specs.

■It can be used to adjust the tape running of all helical scan type magnetic recording and reproducing devices such as VTR and DAT.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a test signal of an embodiment recorded on the tape of the present invention and used in the method of the present invention, and FIG. 2 is a waveform diagram of essential parts of a test signal of an embodiment of the present invention. FIG. 3 is a block system diagram showing one embodiment of the signal generator used in the present invention, FIG. 4 is a block system diagram showing an embodiment of the main part of FIG. 3, and FIG. 5 is the main part of FIG. 6 is a time chart for explaining the operation of FIG. 5, FIG. 7 is an explanatory diagram of the characteristic factors of demagnetization, and FIG. 8 is a diagram for inspection used in the conventional method. FIG. 9, which is an explanatory diagram of signals, is a diagram showing the recording and reproducing frequency characteristics of the magnetic recording and reproducing device. Vl, V2...Vertical synchronization signal, H, S...Horizontal synchronization signal, Mo, M+, M2, Mo-, M+M2-...
- Marker, 1... Signal generator, 2... Video oscillator, 13... Switching point (SW, P) marker correction circuit, 27.28... Monostable multivibrator (MM), 29. 30...Flip 70 to J-. Patent applicant Victor Co., Ltd. - Ω Hiko2x 11 ℃ ■

Claims (5)

[Claims] (1) Among the recording tracks sequentially formed by the rotating head, one of the two adjacent recording tracks has a first
A first FM signal frequency-modulated with a video signal at a level of A magnetic tape for adjusting tape running, characterized in that an FM signal of No. 2 is recorded. (2) A magnetic tape for adjusting tape running according to claim 1, wherein each of the first and second level video signals is provided with a marker indicating an allowable range and center position of a switching point. . (3) The recorded first and second FM signals of the magnetic tape for tape running adjustment according to claim 1 or 2 are reproduced by the magnetic recording/reproducing device to be adjusted, and at least the envelope and the reproduced signal after FM demodulation are reproduced. A tape running adjustment inspection method comprising adjusting a tape running system of the magnetic recording/reproducing apparatus based on either one of the above. (4) A video signal of a first level and a video signal of a second level that differs by a certain level compared to the first level are
The first FM signal frequency-modulated by the first level video signal and the second FM signal are alternately supplied to the magnetic recording/reproducing device to be inspected every track scanning period, and the first FM signal frequency-modulated by the video signal at the first level and the second FM signal are transmitted onto the magnetic tape by the magnetic recording/reproducing device. A second FM signal frequency-modulated with a video signal at a level of
A tape running adjustment inspection method comprising inspecting a tape running system of the magnetic recording/reproducing apparatus based on at least one of a signal envelope and a reproduced signal after FM demodulation. (5) The tape running adjustment inspection method according to claim 4, wherein a marker indicating an allowable range and center position of a switching point is added to each of the first and second level video signals.