JPS63304418A - Vtr head gap position detecting method - Google Patents

Abstract

PURPOSE:To attain position detection with high reliability by picking up a head image with a lower magnification from an image, identifying the area by a binary picture, approximating the contour by plural straight lines and detecting a rough position of the head gap from the cross points of the straight lines and picking up only the vicinity with a high magnification. CONSTITUTION:A head of a VTR cylinder 32 is picked up by a TV camera 31 at a low magnification on a base 30, the result is converted into a digital signal and inputted to an auxiliary processing circuit 34. The signal is stored in a memory 39 via an interface I/F 38 and displayed on a monitor 33 via an I/F 41 and an exclusive circuit 40 divides the signal into recognition object, background and noise. The picture processing unit 35 uses a CPU 34, which detects a gap coarse position of the ferrite from an external address of the recognition object obtained from the exclusive circuit 40 of the auxiliary device 34 according to the program memory 44. Then the local pickup with high magnification is applied and processing is applied by a magnified picture to apply accurate positioning. Through the structure above, the recognition object is detected efficiently at a high speed without noise misdetection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a VTR head gap position detection method that determines the gap position from a photographed image of the tip of a VTR head by binary image processing, and particularly relates to a method for detecting a gap position of a VTR head with high speed and high reliability. The present invention relates to a VTR head gap position detection method suitable for detecting the position of a VTR head.

[Conventional technology]

First, the recognition target of the present invention will be explained. Figure 2 shows VT
This figure shows the upper cylinder of R, in which heads 2 and 2' for reading tape signals are respectively tightened to the upper cylinder 1 with assembly screws 3.3'. Figure 3 shows heads 2, 2'
FIG. 4 is an enlarged view of section A in FIG. 3. 5 is a plan view of the head 2 taken from the direction of arrow B in FIG. 2, and FIG. 6 is a plan view of the head 2 taken from the direction of arrow C in FIG. Generally, when attaching the VTR heads 2, 2' to the upper cylinder 1, the angle indexing amount a (the rotational direction of the L head 2 and R head 2') is relative position), helad 2 and 2'
Projection amount b from the upper cylinder 1, height C1 of the heads 2 and 2' from the rotating surface of the upper cylinder 1, posture alignment d (
It is necessary to adjust four items (relative position between the head gap 20 and the apex of the curve of the upper cylinder 1), and all of them must be adjusted with precision on the order of microns.

In the present invention, the head gap position in this attitude adjustment item is recognized.

Conventional VTR bed gap position recognition means.

As described in Japanese Patent Application Laid-Open No. 139326/1982, a gap signal is detected based on an enlarged input image of the head gap portion taken on a monitor TV screen, and the VTR head is moved so that this gap signal is maximized. By letting VT
The position of the tip of the R head is detected, making it possible to measure the gap position.

[Problem that the invention seeks to solve]

The conventional method described above also detects noise caused by foreign matter adhering to the vicinity of the gap of the ferrite part of the VTR head, or when some shape change occurs. There was a problem that it was difficult to distinguish it from a gap signal. Also, what is the optical equipment used at that time?

Since the optical magnification is high enough to detect the gap signal through image processing, the monitor image is enlarged and too localized.
There was a problem that it was difficult to find the vicinity of the gap.

An object of the present invention is to provide a method for detecting the head gap position at high speed and with high reliability without erroneously detecting the vicinity of the gap even if the above-mentioned foreign matter adheres or changes in shape occur.

[Means for solving problems]

The above purpose is to photograph the recognition target (in this case, the tip of the VTR head) using an optical device with a low optical magnification, and convert the resulting image into a binary image with a certain threshold value as the density value. Processing, the rough position of the gap is detected by extracting the outer shape of the head phaate part and the edge of the lower edge (or upper edge) of the outer edge.Then, based on the detection results, the height of only the vicinity of the gap is detected using a magnifying lens. This is achieved by obtaining a magnification image and detecting the precise position of the gap.

[Effect]

Recognition using an optical device with low optical magnification.

An image of the object is captured, the outer contour of the VTR head ferrite part in the image is converted into a series of dots, and two points near the gap in the lower edge of the series of contour points are found based on a certain algorithm.The midpoint of the two points is found. Since it almost coincides with the lower end point of the actual head gap, it is possible to roughly detect the position of the gap. As a result, the rough position of the gap can be used for searching near the gap during high-magnification photography and as a reference for the window setting position to improve image processing efficiency. Therefore, by imaging and detecting only the vicinity of this rough position at a high optical magnification, it is possible to detect the gap position at high speed and with precision.

FIG. 1 is a flowchart showing an algorithm for detecting the position of a VTR head according to the present invention.

〔Example〕

An embodiment of the present invention will be described below.

FIGS. 7 and 8 show VTs used for detection in this embodiment, which have a function of dividing image data into bright and dark areas in a black and white pattern.
The external and electrical configurations of the R head gap detection device are shown. In FIG. 7, a television camera 31 photographs the head portion of a VTR cylinder 32 mounted on a stage 30, and the electric signal at that time is converted into a digital signal and input to an auxiliary image processing device M. It looks like this. In the auxiliary image processing bag [34, as shown in FIG. 8, the input electrical signals are stored as image data in the image memory 39 via the interface section 38. This image data is displayed on the monitor 33 via an interface section 41, and is divided into regions by a dedicated circuit 40 into a recognition target (VTR head ferrite section), a background region, and a noise region. In addition, in order to improve the image processing efficiency of the CRT, the CPU 43 uses the external address of the VTR edge ferrite section obtained from the dedicated circuit 40 in the auxiliary image processing bag [34] according to the progera t1 stored in the program memory 44. From this, the gap position of the ferrite portion is detected. Further, the stage 30 is configured to move up and down via an interface section 42 within the image processing apparatus. The floppy drive device 37 is for loading various programs stored on the floppy disk into the program memory 44 via the interface section 45, and the keyboard 36 is for inputting operation details and various data. For the sake of
The input contents are displayed on the CRT for confirmation.

The algorithm for detecting the gap position will be explained below according to the flowchart shown in FIG.

In FIG. 9, a binary image is divided into regions using a certain density as a threshold value, using a captured image of the head tip when the optical magnification is low as an input image.

Here, the area of binary image segmentation is defined as a certain brightness (also called density) as a threshold value, and all image points are divided into either bright points or dark points based on that threshold value. In the binary image diagram of FIG. 9, which refers to a collection of adjacent image points that are generated by distinction, blank areas indicate bright areas,
The shaded areas indicate dark areas. The area indicated by reference numeral 50 is the ferrite part of the V'r R head including the gap part to be recognized, and 51 is the background. Further, 52 and 53 are noise areas generated due to foreign objects, deformation, etc.

As is clear from this figure, except for area 51, area 5
0°52 and 53 indicate bright parts. The above is the first
This is a processing process indicated by reference numeral 10.11 in the figure.

Next, the outline of the ferrite portion is extracted, which is processing step 12 in FIG. The auxiliary image processing device M calculates and selects the one with the largest area among a plurality of bright regions, as shown in FIG.
The outline of the region 50 having the maximum area is approximated by a series of points. Since the region 50 with the largest area has a boundary with respect to the background 51, the above point sequence approximation is possible.

The next processing step 13, lower end point sequence extraction, means that when the above point sequence is divided into appropriate partial point sequences, a partial point sequence that includes the gap position (here, the lower end point sequence) is extracted from among them. It is. This can be done as follows. First, store the X and Y coordinates of all points in the image memory 39.
The point 55 with the smallest X coordinate value is detected as shown in FIG. The coordinates at that time are (PX)P
! /) Toshi, ah.

Let the point sequence 57 be a point sequence whose X coordinate is an X value that satisfies the following: Px≦X≦Px+Δα. Similarly, the coordinates of the point 56 with the largest X coordinate value are (
Qx, Qy), and when an appropriate distance is Δβ, Qx≦
The point sequence whose X coordinate is the value of X' that satisfies X'≦Qx+Δβ is defined as a point sequence 58. Next, from the remaining point sequence set, select a point sequence whose Y coordinate value is larger than a certain value (for example, the intermediate value between the maximum and minimum value of the X coordinate in the point sequence 57), and select it as the point sequence 59 Let the small point sequence be a point sequence 60. By the above method, it is possible to create roughly four partial point sequences, as shown in FIG. Therefore, as shown in FIG. 13, a point sequence 60 (lower end point sequence) can be extracted as a partial point sequence including the gap position.

The next processing step 14 is to further divide the extracted lower end point sequence into areas using straight lines, and the method will be described below. That is, the slope of the straight line connecting points 61 and 62 shown in FIG.
11 If the slope of the straight line connecting points 62 and 63 is m2, and k is a certain constant, then if m, 7m1<k, then points 61 to 63 are regarded as one straight line. , the partial point sequence area of the lower end point sequence forms five straight lines from 64 to 68 as shown in FIG.

The next process is to extract the straight line @65.66 and then 68 based on the slope of each straight line and the coordinates of the end points, and then extract the 16th line.
The intersection 69 of the straight line 65 and the straight line 66 shown in the figure, and the straight line 6
6 and the straight line 68, and further calculate this intersection 6
From the value of 9.70, a midpoint 71 between the two points is calculated.

Since the address of the point 71 obtained in this way almost coincides with the gap lower end point 54, this point 71 can be considered to be the rough position of the gap.

Although the above position detection algorithm has been described as extracting a sequence of lower end points, it is clear that the rough position of the gap can also be detected by extracting a sequence of upper end points.

Since the posture alignment of the VTR head position adjustment item needs to be adjusted on the micron order, this gap position detection must also be performed precisely. Therefore, the optical magnification may be set higher than that for rough gap position detection. In this case, this local imaging includes the point 71 detected by the above method.
The stage 30 can be moved using the coordinates as clues, and the target can be captured by the television camera 31. Also, the first
As shown in the enlarged captured image in FIG. 7, when deciding where to set the window 72 used to limit the processing range to improve image processing efficiency, the above-mentioned rough gap position is set to the window 72. If the ferrite portion in the window 72 is photographed at a high magnification by using the center point of the gap as the center point, it becomes possible to detect the gap lower end position 54 at high speed and without erroneously detecting noise.

〔Effect of the invention〕

According to the present invention, it is possible to extract and measure the gap position of the VTR head ferrite portion without erroneously detecting it, and it is possible to improve the reliability of head posture alignment, which is a function of VTR head adjustment. . In addition, as the optical means for gap detection, a two-step method is adopted in which the rough position is determined by imaging at low magnification, and then the optical magnification is increased to measure the precise position, making it possible to detect the gap position at high speed. become.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gap position detection algorithm according to the present invention, FIGS. 2 to 6 are explanatory diagrams showing recognition targets according to the present invention, and FIGS. 7 and 8 are one embodiment of the present invention. 9 to 17 are explanatory diagrams for explaining the algorithm of the present invention. Explanation of symbols 30...Stage 31...TV camera 3
2...VTR cylinder 33...Monitor 34--
Auxiliary image processing device 35--Image processing device 39...
Image memory 4o...Dedicated circuit 43...CP
U 44...Patent attorney representing the program Junnosuke Nakamura 11 da pre 2 figures, -A; 2, 2' to...to 1 door 31'! l 14:
¥9 Group b3 'ilo last 12 sentences 5q t'13 Kawaya 14 letters 15 figures x4. -160

Claims (1)

[Claims] 1. Capturing the recording/playback gap of the VTR head with high optical magnification, converting the captured image into a black and white binary image, and detecting the gap position through image processing that identifies each series of black and white images as a single image area. In the VTR head gap position detection method, a VTR head image is captured in advance at an optical magnification lower than the optical magnification used for the above imaging, a VTR head image area is identified from the binary image, and a plurality of outline edges of the area are identified. Approximate by a straight line of
A VTR head characterized in that the rough position of the recording/playback gap of the VTR head is detected from the intersection of these straight lines, and then the gap position is detected by imaging only the vicinity of the rough position at the high optical magnification. Gap position detection method.