JPS62120618A - Method for inspecting relative position of fixed magnetic head - Google Patents

Abstract

PURPOSE:To measure rapidly and precisely a shear by simultaneously measuring the absolute value of the shear based on data obtained at the time of an inspection. CONSTITUTION:An inspecting magnetic tape 2 is obtained by forming the 1st and 2nd inspecting signal bands 51, 52 with the same width on both the side parts of a sound track 5 and forming a no-signal band 50 on the center part and the 1st and 2nd inspecting signals X, Y having different frequency each other are recorded in the 1st and 2nd inspecting signal bands 51, 52. A monaural reproduced signal A obtained by reproducing a sound track 5 of the tape 2 by a provided VTR 1 is inputted to the 1st and 2nd detecting parts 2, 4. The 1st and 2nd detecting parts 3, 4 are constituted by connecting the 1st and 2nd level meters 31, 41 to the 1st and 2nd band filters 30, 40 for separating the 1st and 2nd inspecting signals X, Y from the signal A. When a head part 7 of a magnetic head 8 is shifted by (d) downward from an appropriate fitting position, the 2nd inspecting signal band 52 is completely traced by the head part 7, but the width part (d) of the 1st inspecting signal band 51 is not traced. Consequently, the shear of the magnetic head can be discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is useful for determining the mounting position of a magnetic head fixed on a chassis and the running position of a magnetic tape when manufacturing magnetic signal reproducing devices such as VTRs and cassette tape recorders. The present invention relates to a method of inspecting the relative deviation between the two.

(Basic technology) In a signal reproducing device equipped with a magnetic head, the magnetic head is set at an accurate mounting position so that the head portion with a magnetic gap traces the predetermined track surface of the magnetic tape without deviation. It needs to be fixed properly.

Conventionally, for this purpose, an inspection device as shown in FIGS.
).

This device consists of a magnetic tape for inspection (2) on which a test signal is recorded in advance at a predetermined level, and a level meter (6) for measuring the output level of the reproduced signal. As shown in Figure 10, the head part of the magnetic head (
7) Two test signal bands (55) (5B) in which test signals are recorded on both sides of the audio signal band (57)
has been established.

If the magnetic head is attached to the chassis of the VTR to be inspected (hereinafter referred to as the test VTR (1)) in the correct position and orientation, no output will appear on the level meter (6), but if the magnetic head is attached to the If there is an error, the head part (7)
Either test signal band (55) or (56)
), and an output corresponding to the installation error appears on the level meter (6).

Therefore, the mounting position of the magnetic head may be adjusted to 'A' so that the output becomes zero.

(Problem to be Solved) When quantitatively measuring the r deviation in the vertical position of the magnetic head using the above 'A position, the head part (7) is located in the signal band (55) (
56) and the output V of the level meter (6), V = aT, where a is a device-specific constant consisting of the signal reproduction characteristics of the VTR, the recording density, etc.
Since there is a relationship of 2, if the value of a is measured in advance for the sample Vrr;
However, the value of the constant a varies depending on the performance of the magnetic head, the characteristics of the audio circuit, etc.
Even if the model is the same, each machine to be inspected is different, so in order to accurately measure the deviation, it is necessary to conduct an experiment in which the specified T is increased by 4 for each machine to be inspected and to measure ■, in order to find a. can be,
There was a problem in that the work of measuring the deviation was extremely complicated and time consuming.

(Means for Solving the Problems) In the fixed magnetic head relative position inspection method of the present invention, the head portion of the magnetic head installed in the magnetic signal reproducing device under test slides with respect to the magnetic tape for inspection (2). 2 within the signal plane that should touch
Strip test signal bands (51) and (52) are provided with a width equal to the width of the head portion, and first and second test signals X and Y having different frequencies are recorded in both signal bands, respectively.

When inspecting the relative position, use the above magnetic tape for inspection (2
) is attached to the magnetic signal reproducing device under test, and the monaural reproduced signal A detected by the head section is connected to the signal detection means, and the means separates the first test signal X from the monaural reproduced signal A and detects the signal level. At the same time, the second test signal Y is separated from the monaural reproduction signal A and its signal level is displayed.

(Function) When the magnetic head (8) is fixed at an accurate position, the head portion (7) is connected to the first and second test signal bands (51) (
The first and second test signals X recorded in both signal bands are in sliding contact with 52) without vertical deviation.

Y is mixed and outputted as a monaural reproduction signal A.

Therefore, the first signal separated and displayed by the signal detection means
The test signal X and the second test signal Y each indicate a signal level corresponding to the level at the time of recording. For example, the first
If the recording signal levels of the second test signals X and Y are the same, the reproduced signal levels will also be the same.

If the magnetic head (8) has an installation error in the vertical direction,
The head part (7) protrudes from the signal surface, and there is a portion in one of the test signal bands (51) or (52) that is not traced by the navel part (7). As a result, the output of the test signal X or Y reproduced from the test signal band is lower than the signal level when completely traced. However, the other signal band (52) or (51) is
7), it shows an output level corresponding to the signal level at the time of recording (see FIGS. 4 and 5).

Therefore, depending on which output of the first test signal X and the second test signal Y decreases, it is possible to know whether there is a shift of the magnetic head (8) with respect to the magnetic tape (2) and its direction.

The vertical mounting error of the magnetic head (8) can be quantitatively measured from the signal levels V, V2 reproduced from the first and second test signal bands (51, 52). That is, since the output V of the detection section is expressed as a function of the width T in which the head section (7) traces the signal band as described above, as V=aT2, the first test signal band (51) and the first test signal band (51) 2
Assuming that the width of the test signal band (52) is T and the deviation of the head (7) from the test signal band is d, the following relational expression is obtained.

V 1 = a T 6 ” V 2 = a (T, -d) 2 Here, V , , V, and T are known numbers, so d can be directly determined from these relational expressions.

(Effects of the Invention) According to the method for inspecting the relative position of a fixed magnetic head according to the present invention, it is possible not only to detect the presence or absence of a relative deviation between the mounting position of the magnetic head and the running position of the magnetic tape, but also to detect the direction thereof. It is possible to simultaneously measure the absolute value of deviation based on data obtained during inspection.

Therefore, unlike the conventional method, it is not necessary to obtain the value of the constant a beforehand (in summer), and the deviation can be measured quickly and accurately.

(Embodiment) FIG. 1 is a block diagram showing an example of a relative position inspection device configured to apply the position inspection method according to the present invention to a VTR. As shown in Fig. 73, a video trunk (53), a control track (54), and monaural audio ranks 1 to 5 are formed on side No. 171 of the magnetic tape.

The magnetic tape for inspection (2) used in the apparatus shown in Fig. 1 is attached to the head part (7) of the head (8) as shown in Fig. 3.
The first and second test signal bands (51) and (52) are arranged with the same width (for example, 0
．． 35 mm), with a no-signal band (50) in the center, and the full width of both test signal bands (for example, 1.0 mm).
5 mm) corresponds to the width of the hemlock part (7).

In the first test signal band (51) and the second test signal band (52), a first test signal X and a second test signal Y having different frequencies are recorded at a constant level, respectively.

A first detection section (3) and a second detection section (4) constituting the signal detection means are connected to the VTR under test (1) as shown in FIG. 1), a monaural reproduction signal A obtained by reproducing the audio track (5) of the magnetic tape for inspection (2) is input.

The first detection section (3) is configured by connecting a second level meter (31) to a first band filter (30) that separates the first test signal X from the monaural reproduction signal A.

Further, the second detection section (4) detects a second signal from the monaural reproduction signal A.
a second band filter (40) that separates the test signal Y of
t1゛1 by connecting the second level meter (41) to
will be accomplished.

For example, as shown in FIG. 4, when the head portion (7) of the magnetic head (8) is shifted downward by a distance d from the proper mounting position, the second test signal band (52) is lower than the head portion (7).
Even though the first test signal band (51) is completely traced by 1, a width portion d of the first test signal band (51) is not traced. Therefore, the signal level ■1 displayed by the first detection section (3) is lower than the reliability level V2 displayed by the second detection section (4). This reveals that the magnetic head (8) has shifted downward.

As described above, the deviation amount d is the width T of the measurement data V1, 2 and the test signal bands (51) and (52). It can be calculated from

Furthermore, as shown in FIG. 5, even when the head portion (7) is displaced upward, the displacement can be detected in the same manner as described above.

FIG. 2 is a block diagram showing an embodiment of the present invention. According to the relative position inspection device, the magnetic head (8) can be detected not to be vertically misaligned, but can be detected by the magnetic tape (8) as shown in FIG. 2) is inclined to the magnetic head (8), or the magnetic tape (2) is unevenly abutting the magnetic head (8) as shown in Figures 7 and 8. It is also possible to detect the presence of humans as shown in the comic.

The audio track (5) of the inspection magnetic tape (2) used in the apparatus shown in FIG. 2 contains a first main inspection signal X1 and a first sub-inspection signal
A constant level signal obtained by superimposing the second main test signal Y1 and the second sub test signal Y2, which have different frequencies, is recorded as the second test signal Y. has been done. Note that the frequencies of these test signals have the following relationship.

XI<<X2, Yl<<Y2X, <<Y2 The first detection section (3) separates the first main test signal Xl and the first sub-test signal
The main band filter (32) and the first sub-band filter (
33), a first main level meter (34) and a first sub-level meter (35) are respectively connected thereto.

Further, the second detection section (4) detects a second signal from the monaural reproduction signal A.
A second main level meter (44) and a second sub level meter (45 ) is connected to the husband.

Below, we will discuss how the displayed values of each level meter change depending on various symptoms.

Symptom (i) If the magnetic head (8) is located 3' below the proper measuring position as shown in Fig. 4, the same as the inspection device shown in Fig. 1. ) and the first sub-level meter (35) decrease at the same rate, and the outputs of the second main level meter (44) and the second sub-level meter (45) remain unchanged.

Symptom (ii) If the magnetic head (8) is deviated above the proper mounting position as shown in Figure 5, the second main level meter (44) and second sub level meter (45) decreases at the same rate, and the outputs of the first main level meter 7 (34) and the first sub level meter (35) remain unchanged.

Symptom (iii) As shown in Figure 6, magnetic tape (2
) runs at an angle with respect to the magnetic head (8), and an azimuth angle θ occurs between the two. In this case, a so-called azimuth loss occurs in the monaural reproduction signal A, and each level meter (34) (35) ( 44)
Although the output of (45) decreases, the azimuth loss increases as the frequency of the reproduced signal increases. and second main level meter (44)
The decrease in the output of the first sub-level meter (35) and the second sub-level meter (45) is greater than the decrease in the output of the first sub-level meter (35) and the second sub-level meter (45).

Symptom (iv> As shown in FIG. 7, if the magnetic tape (2) is not in good contact with the upper end of the head section (7), a so-called spacing loss occurs, and the first main level meter (34)
and the output of the first sub-level meter (35) decreases,
The spacing loss increases as the frequency of the reproduction signal increases, so due to the difference in recording frequency (Xl<<X2), the output of the first sub-level meter (35) decreases more than ) output drop becomes large.

Symptom (v) When the magnetic tape (2) has poor contact with the lower end of the head (7) as shown in Figure 8.Contrary to the above case, the second main level meter (44) and the second sub level meter (44) Although the output of the meter (45) decreases, due to the difference in recording frequencies (Y l << Y 2), the output of the second sub-level meter (45) decreases compared to the decrease in the output of the second main level meter (44). The output decreases greatly.

Changes in level meter output for each of the above symptoms are shown in a table. Here, O indicates that the output level is normal, Δ indicates that the output level has decreased slightly, and xlj output level has decreased significantly.

Therefore, by observing the amount of decrease in the output of each level meter, it is possible to determine what kind of error is occurring in the relative position r relationship between the magnetic head (8) and the magnetic tape (2). .

On the other hand, in the conventional devices shown in FIGS. 9 and 10, when azimuth loss occurs as shown in FIG.
If a spacing loss occurs as shown in the figure and Fig. 8, it is impossible to detect it because no output will appear on the level meter (6) unless there is an error in the vertical position of the magnetic head (8). Can not.

As shown in FIG. 8, it is extremely rare for a spacing loss to occur at the lower end of the head section (7), so the test signal Y recorded in the second test signal band (52) is as shown in FIG. It is also possible to use a partial level signal with a single frequency, similar to the test equipment of .

The configuration of each part of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the technical scope of the claims.

For example, the signal detection means includes not only a combination of a filter and a level meter, but also an AD converter that converts a monaural reproduction signal into a digital signal, and a frequency analysis of the digital signal to determine the level of the test signals X and Y. It is also possible to create jM using a microcomputer or the like written with a program called Progera for calculating the value.

Furthermore, it goes without saying that the inspection method of the present invention can be used not only for adjusting the mounting position of the magnetic head but also for detecting errors in the running position of the magnetic tape.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of a method for inspecting the relative position of a fixed magnetic head according to the present invention, Fig. 2 is a block diagram showing an embodiment of the method for inspecting the relative position of fixed magnetic heads, and Fig. 3 is a block diagram showing an embodiment of the method for inspecting the relative position of a fixed magnetic head. FIGS. 40 and 5 are explanatory diagrams showing the position of the test signal band that has been detected. FIGS. ;
Explanation of the situation where the magnetic tape is running at an angle to the head part [4. Figures 7 and 8 are partially cutaway side views of the magnetic head and the magnetic tape, respectively, showing the case where the magnetic tape has poor contact with the head part. The figure is a block diagram of a conventional device, and FIG. 10 shows the test I.
It is an explanatory view showing the position of a signal band. (1) Test VTR (2) Magnetic tape (3)
...First detection section (4)...Second detection section A...
Monaural playback signal

Claims (1)

[Scope of Claims] [1] Two test signal bands ( 51) (52) is provided with a width equal to the width of the head part, first and second test signals X and Y having different frequencies are respectively recorded in both signal bands, and the magnetic tape (2) is used as a test magnetic It is attached to a signal reproducing device and connects the monaural reproduced signal A detected by the head section to a signal detection means, and the means separates the first test signal X from the monaural reproduced signal A and displays the signal level. Also, a method for inspecting the relative position of a fixed magnetic head, which separates a second inspection signal Y from a monaural reproduction signal A and displays the signal level. [2] The method for inspecting the relative position of a fixed magnetic head according to claim 1, wherein the first and second inspection signals X and Y are constant level signals each having a single frequency. [3] The first test signal Second main test signal Y_1 and second sub test signal Y
2. The relative position inspection method of a fixed magnetic head according to claim 1, wherein the constant level signal is obtained by superimposing _2.