JPS63256063A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To attain excellent automatic focusing with simple constitution by extracting a picture element data located in a direction in crossing with a border of dark/bright parts of an object so as to apply signal processings such as noise elimination of a filter means, differentiation by a differentiation means and integration by an integration means. CONSTITUTION:A signal processing section 22 reads a brightness data of a picture element located on a center line QL passing through the image pickup center in the Y direction among data in a memory 24 and filtering processing by a filter 26 is applied. Then the differentiation processing by a differentiation device 28 is applied. A differentiation data obtained similarly as above is stored in a memory 30 and the differentiation data of this time is stored in a memory 32 by the control of a control section 36. The differentiation data stored respectively in the memories 30, 32 is outputted to an integration section 34, integrated for each time and the integrated data is compared by a comparison drive section 38. The integrated value or area of the differentiation data is maximum at focusing. Thus, an adjusting ring 14 is driven to maximize the integrated value.

Description

[Detailed Description of the Invention] [Field of Application in Industry A] The present invention relates to an automatic focusing device, and is necessary for, for example, groove tracing control, welding condition control, and welding torch height control in welding equipment. This invention relates to an automatic focusing device suitable for detecting grooves and the like.

[Prior Art] Some conventional automatic focusing devices have been put into practical use in the fields of still cameras, video cameras, and the like.

These automatic focusing devices include those that actively irradiate the subject with infrared rays, ultrasonic waves, etc. for focusing, and those that receive optical signals from the subject with sensor means that performs photoelectric conversion, and then Some types perform focusing by performing signal processing.

[Problems to be Solved by the Invention] However, the conventional automatic focusing device as described above has a very complicated structure because the objects to be photographed are diverse.

By the way, in certain fields, for example, in fields where industrial television cameras are used, the objects to be photographed are limited to some extent, and it is often sufficient to focus on a particular object. In such a case, it is sufficient to perform automatic focusing only on that subject.

The present invention has been made in view of the above points, and can be applied to cases where the brightness/darkness boundary of the subject intersects with a preset line within the imaging field of view, and achieves good automatic focusing with a simple configuration. The object of the present invention is to provide an automatic focusing device that can perform the following functions.

[Means for Solving the Problems] In an automatic focusing device that focuses on a subject by driving a focusing mechanism of an imaging means, the present invention provides an automatic focusing device that focuses on a subject by driving a focusing mechanism of an imaging means. data extraction means for extracting pixel data located in a direction intersecting the bright/dark boundary; filter means for filtering the extracted data to remove noise; differentiation means for performing differential processing on the filtered data; and a control drive means for driving a focusing mechanism of the imaging means so that the integrated value is maximized. .

[Operation] According to the present invention, first, pixel data located in a direction intersecting the brightness/darkness boundary of the subject is extracted by the data extraction means.

These pixel data are subjected to signal processing such as noise removal by the filter means, differentiation by the differentiating means, and integration by the integrating means.

Then, the focusing mechanism of the imaging means is driven by the control driving means so that the integrated value is maximized, that is, the contrast between the bright and dark boundaries of the subject is maximized.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

衷jfE <91 (λλWe FIG. 1 shows an example of an industrial television camera to which an embodiment of the automatic focusing device according to the present invention is applied.

In this figure, the industrial television camera 10 has a main body 12
, a lens 16 equipped with an adjustment ring 14 for focusing, and a drive device 18 for rotationally driving the adjustment ring 14.
It has

The automatic focusing device 20 according to this embodiment includes the main body 12
and a driving device 18, and focuses on the subject M by controlling the amount of rotation of the adjustment ring 14 by the driving device 18 based on the image signal or video signal from the industrial television camera body 12. It is something.

In addition, in FIG. 1, for the purpose of explanation, an industrial television camera 1 is shown.
0 and the automatic focusing device 20, in an actual device, the automatic focusing device 20 is built into the industrial television camera 10.

Next, referring to FIG. 2, the above-mentioned automatic focusing device 2
The configuration of 0 will be explained. In FIG. 2, the video signal of the imaged object M or the luminance data of each pixel is as follows:
The signal is input to the signal processing section 22. The signal processing unit 22 includes a memory 24 that temporarily stores manually input video signals or brightness data of each pixel, a filter 26 that performs a filtering process (described later) on the brightness data of a predetermined pixel, and a differential process. A differentiator 28 is provided for each.

This signal IA processing section 2 stores the human data in the memory 24, and also stores the human data on the center line (described later) that passes through the imaging center of the industrial television camera 10, out of the stored luminance data of each pixel in the two-dimensional array. The brightness data of the located pixel is read out, and the filter 26 and the differentiator 2 are applied to these data.
It has a function to perform the processing according to 8.

Next, the data output side of the signal processing section 22 is connected to a memory 30.
32, respectively, and these memories 30 and 32
The data output side of is the integrator 34A, 34B of the integrator 34.
are connected to each.

Furthermore, a control section 36 is connected to each of the signal processing section 22, memory 30.degree. 32, and integration section 34 described above.

Among the above units, the memory 30.32 is the signal processing unit 2.
This is for temporarily storing the luminance data of each pixel processed in step 2, and the data from the previous one-screen image capture of the industrial television camera 10 and the current data are stored alternately. It has become.

Further, the integration section 34 has a function of integrating the data stored in the memories 30 and 32.

Further, the control unit 36 controls the writing of data into the memories 30 and 32 alternately, and also controls the reading of data to the integration unit 34 and the start and reset operations of the integration unit 34. It is something.

Next, the integration output side of the above-described integration section 34 is connected to a comparison drive section 38, and the output side of this comparison drive section 38 is connected to the motor 40 of the drive device 18 shown in FIG.

The comparison drive unit 38 compares the integrated value during the previous imaging and the integrated value during the current imaging, determines the rotational direction of the motor 40 based on the comparison result, and rotates the motor by a predetermined amount in this direction. It has a function of issuing a drive command so that 40 rotates.

Effects of the Embodiment Next, the effects of the above embodiment will be explained with reference to FIGS. 3 and 4.

FIG. 3 shows the action of each part as a graph, and FIG. 4 shows the action of each part as a flowchart.

The following description will be made using an example in which a checkered subject M as shown in FIG. 1 is imaged by the industrial television camera 10.

Further, it is assumed that the adjustment ring 14 is sequentially rotated, for example, with the focal point position at infinity as a reference.

FIG. 3(A) shows an example of a captured image. The luminance data of each pixel of this image is stored in the signal processing unit 22
and is stored in the memory 24 (see step SA in FIG. 4).

Next, the signal processing unit 22 reads out the luminance data of pixels located on the center line QL passing through the imaging center in the Y direction from among the data in the memory 24 (see step SC).

The solid line graph LA in FIG. 3(B) is an analog representation of the luminance of such a pixel. Filtering processing is performed on these data by the filter 26 (see step SC). 1 This filtering is performed, for example, by averaging luminance data for adjacent pixels. For example, if the luminance data of the pixel to be processed is 141, and the luminance data of the adjacent pixel is b I-1+ 1) 141, then the filtered pixel data B1 is
An operation expressed as l+bμ, )/3 is performed on the luminance data of each pixel.

As a result of such filtering processing, the graph LA in FIG. 3(B) is smoothed like the graph LB in FIG. 3(C), and the influence of noise is reduced.

Next, the differentiator 28 performs differentiation processing on the luminance data that has been filtered as described above (see step SC).

This differentiation process is performed, for example, by calculating the absolute value of the difference between the filtered data of the pixels that are separated by a predetermined path between the left and right sides. For example, let the differential data of the pixel to be processed be ri, and the filtering data located first on the left and right are dl-n and dl+, respectively. Then, D r = l d r −n
An operation represented by d l+ n + is performed.

As a result of such differential processing, the graph LB in Fig. 3(C)
becomes like the graph LC shown by the solid line in FIG.

Here, assuming that the memory 30 stores the differential data obtained in the same manner as the previous time, the current differential data is stored in the memory 32 under the control of the control unit 36.

Next, when the current differential data is stored, the control unit 3
6, the differential data respectively stored in the memories 30 and 32 are output to the integrating section 34, and the integrating section 34 integrates the manual differential data each time (see step SE), and the integrated data is subjected to comparison drive. The comparison is made in section 38.

Here, when comparing the in-focus state and the out-of-focus state, Fig. 3 CB
) to (D), the broken lines indicate each data when out of focus.
When out of focus, the outline of the subject is blurred, the contrast is low, and the slope of the brightness data of pixels at the boundary between brightness and darkness becomes small. Therefore, the integral value or area of the differential data in FIG. This area is determined by the integration unit 34
It is obtained by integrating by .

Therefore, the adjustment ring 14 (see FIG. 1) is rotated so that the integrated value is maximized.

By the way, even if the current integrated value is larger than the previous integrated value as a result of the comparison by the comparison drive unit 38 (see step SF), there is a possibility that the integrated value becomes even larger.

Therefore, a drive command is issued by the comparison drive section 38 so that the motor 40 is rotated by a predetermined amount in the same direction as the previous time (see step SG).

The above operation is performed when the subject M is photographed by the industrial television camera 10.
This is repeated every time an image is captured. Then, when the comparison drive unit 38 determines that the integrated value of the current differential data is smaller than the integrated value of the previous differential data (see step SF), it is assumed that the in-focus position has just been passed, The comparison drive unit 38 issues a command to rotate the motor 40 by a predetermined amount in the opposite direction to the previous rotation (see step SH).

As a result, the adjustment ring 14 is set at the position where the previous differential data was maximum, that is, at the convergence position.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the operation of the automatic focusing device described above may be performed by software using a microcomputer or the like.

In addition, in the above embodiment, the brightness data of pixels on the center line QL of the image is used, but as shown in FIG. 5, for example, as shown in FIG. Similar processing may also be performed. In this case, for example, the in-focus position may be the state when the differential integrated data on any two lines becomes the maximum, or the state when the differential integrated data on the two lines including the center line QL becomes the maximum. The state of is the in-focus position.

In particular, if the lines QM and QN are set at positions farther away than the center line QL, the entire screen can be focused.

In addition, in the case of a subject with no change in the center line QL force direction contrast as shown in Fig. 6, the center line Q
The above-described processing may be performed on the luminance data of pixels on V. In this way, automatic focusing on a wider variety of subjects becomes possible.

Furthermore, the present invention can be applied to cases where the brightness/darkness boundary of the subject intersects with a preset line within the imaging field of view; an example of this is the detection of a groove in a welding base material. .

[Effects of the Invention] As explained above, according to the present invention, automatic focusing can be performed satisfactorily with a simple configuration when the brightness/darkness boundary of the subject intersects with a preset line within the imaging field of view. It has the effect of being able to

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of an industrial television camera using an embodiment of the present invention, Fig. 2 is a block diagram showing the configuration of an embodiment of the invention, and Fig. 3 shows the operation of the above embodiment. The graph and FIG. 4 are flowcharts showing the operation of the above embodiment, and FIGS. 5 and 6 are explanatory diagrams showing other embodiments. DESCRIPTION OF SYMBOLS 10... Industrial television camera, 14... Adjustment ring, 18... Drive device, 20... Automatic focusing device, 22
...Signal processing section, 24...Memory, 26...Filter, 28...Differentiator, 30.32...Memory, 3
4... Integration unit, 36... Control unit, 38... Comparison drive unit, 40... Motor.

Claims (1)

[Scope of Claims] In an automatic focusing device that focuses on a subject by driving a focusing mechanism of an imaging means, of the signals output from the imaging means, a direction intersecting a brightness boundary of the subject. a data extracting means for extracting pixel data located at , a filtering means for filtering the extracted data for noise removal, a differentiating means for performing differential processing on the filtered data, and a differentiating means for extracting the differentiated data from each other. An automatic focusing device comprising: an integrating means that integrates for each image; and a control drive means that drives the focusing mechanism so that the integrated value becomes maximum.