JPS59109806A - Position recognizing device of segment - Google Patents

Abstract

PURPOSE:To determine a head gap position without the influence of noise, by processing the head scan output due to a galvanometer, a slit corresponding to head gap dimensions, a photosensor, etc. with a prescribed algorithm. CONSTITUTION:A reflected light from a magnetic head 3 for VTR is received by a photosensor 13 through a focusing lens 8, a galvanometer 11, and a slit which is shorter than the gap length of the head 3 and is provided with a through hole similar to a gap focused image. The output of this sensor 13 is subjected to A/D conversion and is stored as waveform data, and minimum values the difference between which and a maximum value of waveform data is a certain value or larger are selected. Average values mean (l) and mean (r) of flat parts on both sides for every minimum value evk in this minimum value group are determined, and a width is determined by the address difference between both flat part ends, and a depth is calculated by the operation based on an equation I . On a basis of these width and depth, the gap position of the head 3 where the minimum value is smallest by scattering is automatically determined without the influence of noise due to dust or the like accurately.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is directed to video recording (hereinafter abbreviated as VTR).
When installing the magnetic head in the assembly process, two left and right VT
When fixing RadPace (hereinafter referred to as head base) to R with screws, a magnetic head (hereinafter referred to as head base) that accurately recognizes how far the center position of the very thin gap of the head fixed to the head base deviates from the predetermined position. This invention relates to a gear position recognition device for a head (hereinafter abbreviated as head).

Configuration of the conventional example and its problems Figure 1 shows the layout of the optical system of the conventional head gear position recognition device, where 1 is the upper cylinder o2
and 2a are head bases to which heads 3 and 3a are each fixed. There is a gap 4 at the tip of the heads 3 and 3a as shown in Fig. 2, and the gap position of the head can be adjusted by moving left and right on the center line AA' of the upper sill.
This is done by slightly moving the mounting position of the left and right RadPace so that the centers of the Rad gaps overlap. ,1
o is a television camera. The light from the light source 7 passes through the glass fiber 6 and illuminates the tip of the video head 3 through the convex lens 8a and the beam splitter 5. video head 3
The reflected light passes through a beam splitter 6 and is focused on a television camera by a convex lens 8, so that a screen as shown in FIG. 2 can be displayed on a television (the television is not shown). Note that the optical filter 9 has a signal-to-noise ratio (S
/N ratio) is placed in front of the television camera. In the conventional example, in Fig. 2, the vertical reference line Y
Adjust in advance so that Y' overlaps the center line AA' of the upper cylinder in Figure 1, and have the operator read the position where the horizontal reference line X Ta. However, when trying to display the entire tip of the video head on a TV camera, the width of the head gap is so narrow that the resolution of the TV screen is insufficient and the gap is displayed faintly, resulting in poor accuracy in determining the gap position. However, even at the same position, there were differences due to individual differences. Unfortunately, there was also a problem with the TV's reference line YY/ drifting electrically.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and it is possible to accurately recognize the position of a small gap in a head within a wide field of view, and to adjust the head installation, which is dependent on the human eye at this size. An object of the present invention is to provide a head gap position recognition device that enables automation of inspection work.

Structure of the Invention The present invention uses an elongated slit that matches the length and inclination of the gap whose position is to be recognized, and scans the surface of an object such as a magnetic head in the horizontal direction through this slit to obtain one-dimensional light intensity signals. an optical system for creating a signal, a photosensor and an A-D converter for converting this light intensity signal into an electric video signal and further converting it into a digital value, and a waveform storage circuit that sequentially stores the obtained digital video signal. , consists of an arithmetic and control device such as a microcomputer that calculates the address of the waveform storage circuit as the gap position from the video signal data of this waveform storage circuit, and its program calculates the noise component included in the video signal and the gap signal. As a result, it has become possible to recognize the position of gaps, which previously relied on human visual judgment.

The optical system uses a galvanometer to scan the image, and by adding a waveform generation circuit that controls the deflection angle of the galvanometer and the write address of the waveform storage circuit, it has a wide field of view and high resolution. It is possible to recognize the location of

A galvanometer made to change the angle of view described in the example,
It shows the mirror part. 12 is a slit whose length is slightly shorter than the length of the gap, and as shown in Figure 3, it is tilted at an angle of θ degrees with respect to the vertical direction, and this angle θ is relative to the vertical direction of the gap 4 of the head in Figure 2. It is the same as the inclination angle θ.

The slit width is approximately the width of the cap magnified and imaged by the convex lens 8. 13 is a photosensor such as a photomultiplier tube. The slit 12 is arranged at a position where the image of the head is formed by the convex lens 8. When the mirror of the galvanometer 12 is rotated, the image of the head also moves horizontally, so when the galvanometer is moving, the slit 1
The light that enters the 7 otosensor 13 through the slit 12 becomes a slit light component as if the head surface traced the XX/ line in Fig. 2 with the slit 12. The photosensor outputs a signal containing noise components such as dust on the head surface and uneven brightness. The point Xp of the lowest signal level in the V-shaped portion in FIG. 5 is the coordinate of the center position of the gap.

The circuit configuration for inputting the information obtained as described above to the waveform storage circuit for the computer to judge will be explained with reference to FIG. The received light is converted into a current by the photosensor 13, then amplified by the amplifier 14, and converted into a voltage output SiG corresponding to the intensity of the light. Voltage output SiG
A high-speed analog-to-digital converter (hereinafter referred to as A)
-D converter) converts the data into digital data MD and inputs it to the waveform storage circuit 16. The clock oscillator 17 sends the clock pulse CLK to the timing control circuit 1.
Send to 8. The timing control circuit 18 outputs an A-D conversion command pulse T1, which will be explained in detail later, receives an A-D conversion end pulse T2, and outputs the A-D converted data MDI.
Outputs the write command/ζrus T3. On the other hand, the clock pulse CLK is also input to the waveform generation circuit 19, and each waveform generation circuit has a built-in counter that increments by one at each timing, and its output is the address signal ADH.
This becomes the write address of the waveform storage circuit 16.

Furthermore, the waveform generation circuit 19 converts the output of the counter and outputs control data GD that changes the deflection angle of the galvanometer, and this GD is converted into an analog voltage by a digital-to-analog converter (abbreviated as a DA converter) 20. The current is converted into a current by an amplifier 14a, and then supplied to the galvanometer 11. 21 is an arithmetic and control device such as a microcomputer equipped with a memory circuit and an input/output interface. The data written in the waveform storage circuit 16 (hereinafter abbreviated as CPU) is read through the control circuit 7ADD and MDO to recognize the coordinates Xp of the gap position of the head.

Next, the procedure for writing data into the waveform storage circuit 16 will be explained using the timing charts of FIGS. 7 and 8.

Clock pulse CLK is constantly output. When starting data acquisition, the CPU first turns off the R/W signal. The R/'W signal is a signal that controls the waveform storage circuit 16. When it is ON, the waveform storage circuit is in the read mode, and when it is OFF, the waveform storage circuit is in the read mode.
It is in write mode. Writing to the waveform storage circuit is possible only in write mode. Subsequently, the CPU outputs a nox (STA signal) to the waveform generation circuit 19 as a start signal. Then, the waveform generation circuit 19 starts outputting the galvanometer control data GD and at the same time turns on the control signal C0NT to the timing control circuit 18. CΦ
While the NT signal is ON, the A-D conversion and waveform storage circuit 16
Writing continues. The current GI of the gallenometer, which is obtained by D-A converting the GD, is a triangular wave as shown in FIG. 7, and increases in proportion to time from to to 11-1.

As mentioned above, the swing angle of the galvanometer 11 is O, which is proportional to the current value, that is, GI, and the galvanometer swings at a constant angular velocity. Therefore, for each clock pulse, A-D
The intensity signal SiG of the light received by the photo sensor 13 to be converted is sampled and input to the waveform storage circuit 16 at regular position intervals. As a result, the image information of the head becomes a signal as shown in FIGS. 5 and 7 SiG.

Now, when the number of clock pulses reaches a certain number M, the C○NT signal is turned off to stop writing, and the deflection angle of the galvanometer is returned to the original stop position.
Reduce the open current GI from l to t2. Then, when the vibration of the galvanometer returns to its original position, an end signal pulse (END) is sent.
Upon receiving this, the 0Cpu which outputs the waveform (curse) to the CPU turns on the R/W signal to the waveform storage circuit 16. The above is the series of steps for importing the data.

Next, A-D conversion and timing of writing to the waveform storage circuit will be explained in detail. In Figure Y, the C0NT signal is O
Only in the case of N, AD conversion and writing to the waveform storage circuit are performed. At the rising edge of clock pulse CLK, A-
D conversion command pulse T1 is sent from timing control circuit 18 to A
-Output to the LD converter. After a while, when the AD conversion of the signal SiG is completed, the AD converter outputs an AD conversion end pulse T2 to the timing control circuit.

A command pulse T3, which is written by watching the falling edge of T2, is output from the timing control circuit 18 to the waveform storage circuit 16, and one data write is completed.

By using the optical system and control circuit as described above, it is possible to divide a one-dimensional image with a very wide field of view into minute parts separated by the slit width and store them in the waveform storage circuit, which makes it possible to store them in the waveform memory circuit. Image information with a wide field of view and high resolution can be obtained. As a result, it is now possible to recognize the position of the gap at the end of the head, which could not be displayed on a TV screen. Furthermore, the slit is made into a long and narrow rectangle, and
Since it is tilted by θ degrees from the vertical direction in accordance with the inclination of the gap, the SIN ratio of image information with respect to noise components on the image due to round or square dust, dents, scratches on the gutter surface, etc. is improved.

Data on the head surface is stored in the waveform storage circuit in the manner described above. The algorithm used to calculate the head gap position using the arithmetic and control unit will be described below.

As seen in FIG. 6, the light level changes on the head surface form a figure 7 shape at the gap position xp. The bottom of the figure 7 is considered to be the gap position.

As a means of finding a shape that forms seven characters from the data stored in the wave memory, we first search for the minimum value. The algorithm is shown in the flowchart of FIG. 9, and the alphabetical symbols used are shown in Table 1.

In FIG. 9, LOOPl searches for the maximum value dmaXl and the minimum value dmin in the order of the wave memory addresses. dma x7dmin >'・・・・・・
(1) When (l is the determined value obtained in advance in an experiment to remove small maximums and minimums due to noise components and to shorten the processing time), escape from L○OP1 and move to A or B. Move. If equation (1) is satisfied by 1 because the maximum value dmax is updated, then the minimum directivity dmi at this time is
Record n as the minimum value e1 and move on to B.

When equation (1) is established by updating the winning minimum value dmln, the process moves to step 8. After B, the maximum value and minimum value are also searched, but in this search, the minimum value dmin is updated as dmin-dmax only when the maximum value dmax is updated. Then, when dmax 'min>l, the process moves to A. After A, search for the maximum value and minimum value, and only when the minimum value dmln is updated, the maximum value dm
Update ax as dmax-dmin, dmax'
When min>', the minimum value dmin is recorded as the minimum value ek and the process moves to B.

The minimum value/maximum value DA1] searched as described above has a feature that the difference between the adjacent minimum value and maximum value is always smaller than l. Therefore, small undulations in the data due to noise etc. can be ignored.

Next, regarding the local minimum values picked out in the above manner, the shape of the data in the vicinity is generally considered to be valley-like, but by knowing the width and depth of this valley, it is possible to determine whether this is a gap or not. Determine whether there is. The algorithm for determining the position of the gap will be explained below. Figure 10 shows
This is a flowchart that determines the width and depth of a valley, determines whether it is a gap based on the values, and determines the position of the gap. FIGS. 11 and 12 are partial detailed flowcharts of the flowchart in FIG. 10. It is.

Table 2 shows the alphabetical symbols used and their definitions.

In FIG. 13 of Table 2, 11 is the width of the address in the predetermined determination range, which is 5 to 2Q times the width of the gap. In Fig. 14, width and clepth are respectively,
It rains the width and depth of the valley.

This will be explained along with the flowchart in FIG. 10 and FIG. 13. The maximum value fmaxl in the address range from the minimum value address ek to ek-11 is assumed.

mol=t-maxl+(1-t)・el)k
--As (2), let n'llB a n l be the average of the data of the waveform storage circuit larger than mOl in the address range from ek'''L to ek.

However, 1. is a predetermined value and must be ○〈t〈1. In the example, t = 0.6. m1il a n l is a value close to the average of the data in the range from ek-11 to ek excluding the deep valley-like cut. Further, similar processing is performed for the data on the right side of ek.

That is, let maxr be the maximum value in the address range from ek to ek+11, and mof = t @max, + (1-t) ・e'
l) k・---...(3), from ek to ek+11
Let meanr be the average of the data of the waveform storage circuit larger than mOr in the range of addresses up to. The meanr is a value close to the average of the data in the range from ek to ek111, excluding the deep valley-like cuts. In FIG. 14, meanl, me
The addresses iml and 1mr on the waveform memory circuit when cutting in the outward direction as seen from ek, with an as the cut level.
Find the difference imr "ml and set it as the width of the valley. Also, set the difference between the average of meanr and meanl and the minimum value evk as the depth of the valley. Let the width and depth of the gap valley be width5t and depth6t, respectively.
wid obtained for the kth extreme value as described above
An evaluation value vk is calculated using equation (4) for th and depth.

・・・ ・ (4) However, K1. 2 is a coefficient determined in advance through experiments, and in the embodiment, values of 1 to 3 are used.

vk represents the degree of difference between the valley at the kth minimum value and the gap of the standard head currently being treated.

Among υ, the minimum value is set to Z' as 1, and the address ek1 of the corresponding minimum value is set as the desired gear position Xp.

The above explanation assumes that the data in the waveform memory circuit is minimal at the gear knob position;
If the signal is inverted by , and becomes an extremely thick value at the gap position, it is obvious that the handling of extremely thick values and extremely minimum values in the recognition algorithm of the present invention may be reversed.

As described above, the position of the minimum value corresponding to the gap can be calculated from among several minimum values caused by noise or dust attached to the head.

The gap position obtained in this way is the data EX, OU
The signal T is output from the CPU to an external automatic adjustment machine, and the upper cylinder is fixed and the mounting position of the head is adjusted.

Up to now, we have explained using Fig. 6 as a control circuit for the optical system shown in Fig. 4, which uses a galvanometer and a photosensor. A similar circuit configuration can be considered in which the gap is captured by a television camera, the one-dimensional image information of only the XX/cross section shown in FIG. '-1: An image sensor may be used as a sensor for image information of the gear knob of the head.

In these cases, the same recognition algorithm as in the embodiment can be used to create a head gap position recognition device.

In the embodiment, only the gap of the magnetic head of a VTR was described as an object, but the present invention is basically to recognize the position of a long and thin straight line segment from image information including noise components of the object.

Effects of the Invention As described above, the present invention stores one-dimensional image information of a magnetic head image including noise components as image information in a waveform storage circuit, and uses the data in an arithmetic control device such as a microcomputer according to the algorithm described above. Using this method, the position of the head gap was calculated and determined, thereby automating the position adjustment of several heads. In addition, the mounting position is highly accurate and variations are reduced, resulting in improved quality.

Furthermore, a galvanometer is placed in the optical path, a slit with the same inclination as the gap is placed at the image formation position of the head, and the light passing through this slit is received by a photo sensor, synchronizing with the deflection of the galvanometer. By configuring the waveform storage circuit to write image information, approximately 11
Narrow gaps less than 171 m in the IIm's wide field of view can now be recognized with an accuracy of within 1 μm.

[Brief explanation of drawings]

Figure 1 is a schematic layout of an optical system in a conventional example, Figure 2 is a diagram of a television screen showing the tip of a magnetic head of a video tape recorder, and Figure 3 is a diagram of an embodiment of the present invention.
Fig. 4 is a schematic layout of the optical system of the embodiment, Fig. 5 is a diagram of changes in the output of the photosensor when an image of the tip of the magnetic head is captured through a slit, and Fig. 6 is a diagram of the embodiment. 7 and 8 are timing charts for writing booter to the waveform storage circuit in the embodiment, and FIGS. 9(a) and 9(b) are block diagrams of the algorithm for searching for maximum and minimum values. Flowchart diagram, Figure 10 (a
), Φ) are flowcharts of the algorithm for determining the gap position, FIGS. 11 and 12 are detailed flowcharts of a part of the flowchart in FIG.
3 and 14 are explanatory diagrams of an algorithm for determining the width and depth of the valley at the minimum position from data in the vicinity of the minimum position. 1------- VTR(7)j Niji IJ 7ri,
2,,,-,,, VTR Henotose, 30・0
II magnetic head, 4Φ・Φ・φ・magnetic head gap, 8・eII...convex lens, 10...000. TV camera, 11---galvanometer, 12・fist・
...slit, 13...-photo sensor =,
15...A-D converter, 16...Waveform storage circuit, 17...Clock oscillator, 18...
...timing control circuit, 19 ... waveform generation circuit, 20 ... D-A converter, 21 ...
...Arithmetic control device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. f Fig. 2 Fig. 6 Fig. 7 Fig. 8 No-1-[''- Fig. 9 Fig. 9(b) Image of Kabako 11R Yo-1 series,
q unFigure 10 (α)

Claims (2)

[Claims] (1) An optical device for obtaining a one-dimensional image signal of the surface of an object, an analog-to-digital converter for converting the image signal of this optical device into a digital value, and a waveform storage circuit for sequentially storing the digital image signal as data. and a first calculating means for searching for a local maximum value and a local minimum value from among the data of the waveform storage circuit; The second step is to select a group of local minima.
and mean values mean and mean of the flat parts within a certain range on both sides of each minimum value evk of the minimum value group.
a third calculating means for calculating t; and a fourth calculating means for calculating a difference w i d t h between the waveform storage circuit addresses on both sides of the minimum value where the data is the average value of the flat part and is closest to the minimum value. and a sixth calculation means for calculating the depth of the valley meanl+meanr of the minimum value as de p t h-2e vk, and the w i d t of each determined minimum value.
A line segment position recognition device comprising a sixth calculation means for selecting one minimum value from a group of minimum values based on h and depth. (2) In the optical device, a galvanometer whose deflection angle can be changed by electric current is arranged in the optical path, a slit having the same inclination as the line segment image is placed at the imaging position of the object image, and the light passing through this slit is an optical system configured to receive light with a photosensor, a timing control circuit that controls the timing of writing image signal data to the analog-to-digital converter and the waveform storage circuit, and an address of the waveform storage circuit and drive of the Gal-Knometer. Line segment position recognition device 0 according to claim 1, comprising a waveform generation circuit that outputs current data and a digital-to-analog converter that converts the output of the waveform generation circuit into current.