JPS63210705A - Light receiver for through hole measurement - Google Patents

Abstract

PURPOSE:To accurately measure the shape and contour of a through hole bored in a work by adding a lens which is shallow in depth of field and has its focus on the surface of the body to be measured to a light receiving part, and reducing the quantity of light received from the background. CONSTITUTION:Light from a light source 18 for measurement is projected on the through hole 13 of the body 11 to be measured and its periphery, and direct light which is incident on the background 17 is cut off by a light shielding plate 16. Further, the light receiving part 19 has a telephoto lens 19 which has shallow depth of field and decreases in the quantity of light extremely where an image is out of focus and the focus of the lens 19a is set on the surface of the through hole 13. Consequently, the lightness difference between the periphery of the through hole 13 and background 17 is emphasized and detected and the contour of an image of the through hole 13 is clear; and light information from the CCD camera of the light receiving part 19 is sent to a display part 21 through an image processing part 20 and displayed as the through hole image A. Then a judgement part 22 receives the through hole information and compares it with the shape, etc., of a reference through hole information signal to judge whether or not the information is within a permissible range, thereby displaying the judgement result on the display part.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention provides a method for determining the suitability of a through-hole in a workpiece in which a through-hole is formed, by checking the surface of the workpiece near the through-hole, including the through-hole. Light is emitted from a light source, the reflected light is received as optical information by the light receiving section, a through-hole image is obtained from the difference in brightness obtained depending on the presence or absence of the reflected light, and furthermore, the through-hole image and the desired reference through-hole are The present invention relates to a light receiving device that can be used in a through hole measuring device that can determine the suitability of a through hole through comparison.

(b) Conventional technology A device for drilling a through hole in a workpiece and measuring whether or not the obtained through hole has the desired basic through hole shape is capable of transmitting light from a light source to the through hole. A through-hole image is obtained by sensing the light information obtained as transmitted light as the difference in brightness and darkness around the through-hole, and by comparing this through-hole image with the desired standard through-hole shape, the through-hole processing can be determined. A through-hole measuring device for determining suitability is known.

An outline of a conventional measuring device will be explained with reference to FIG. (101) is a workpiece, which is a measured object made of a plate-shaped body such as an iron plate, and has a through hole (102) formed therein.

(103) is a light source for measurement, and (104) is a light receiving section that senses light, which are installed facing each other with the through hole (102) in between. In this conventional example, the light receiving section (104) is composed of a CCD camera. The optical information obtained by the light receiving section (104) passes through the image processing section (105) and is displayed on the display section (10) consisting of a CRT screen.
6), image processing is performed to display the through-hole image (a). That is, in this conventional example, the light receiving portion (102) is inserted through the through hole (102).
The transmitted light sensing portion (04) and the other portions are sensed by the light receiving portion (104) as differences in brightness, and the sensed optical information signal is transmitted to the image processing portion (105). The image signal processed in step 105) is displayed on the display section (
106) and displays the image, and the judgment unit (106) receives the image and displays the image.
7). On the other hand, information signals such as the center of gravity position, shape, area, etc. of the reference through hole stored in the reference signal generating section (10g) are also transmitted to the determining section (107). The information on the through-hole (102) image obtained by the image processing unit (105) is then combined with the reference through-hole information stored in the reference signal generation unit (108), such as the shape, area, or center of gravity position of the through-hole image. It is determined whether the shape, area, and center of gravity position of the through-hole image of the through-hole or the reference through-hole are within the error range, and whether or not the through-hole image (a) is suitable is displayed on the display unit (10B). Workpieces are sorted according to the indication of suitability.

In the conventional through-hole measuring device, the measurement light source (103) and the light receiving section (104) must be installed facing each other with the workpiece (1 (11) in between).
If there is no room to install the measuring light source (103) on the opposite side of the workpiece (101), it is difficult to use the conventional measuring device. For example, the workpiece (10
1) consists of a monocoque automobile body, a through hole is formed on the side surface of the automobile body, and the light receiving part (104) is
When installed on the side of an automobile assembly line, the light source must be installed inside the automobile body, but it is generally difficult to install such a light source.

Another possible through-hole measuring device that uses a measurement light source and a CCD camera installed without facing each other is a device that senses reflected light instead of sensing the transmitted light of the through-hole. In other words, this device detects the reflected light around the through-hole of the measurement light source that emits light into the through-hole on the surface of the object to be measured and its surroundings by the light receiving section located on the same side of the object as the measurement light source. do. In this measuring device that uses reflected light, a light receiving section and a measurement light source are installed on one side of the workpiece, and the opposite side of the workpiece is made relatively dark, so that the surroundings of the through hole that generates the reflected light are It is possible to display the through-hole, which is represented as a relatively dark background, as a difference in brightness and darkness, and this difference in brightness and darkness is sensed by the light receiving section, and the sensed through-hole image and the desired reference through-hole image are displayed. Compare the shape, center of gravity position, or area of the image to determine whether it is within the allowable range.

(c) Problems to be Solved by the Invention However, in a measuring device that uses reflected light, unless the background of the through hole in the environment in which the object to be measured is installed is very dark, the background of the through hole and the area around the through hole that is the reflective surface are different. It is necessary to increase the difference in brightness. One way to increase the difference in brightness is to increase the brightness of the reflective surface. That is, in order to increase the difference in brightness and obtain a clear image, the light intensity of the measurement light source is increased, for example, a 500W condensing halogen lamp is used, and the surface of the workpiece to be measured is 300012X. This is a device that increases the illuminance.

However, in the case of this device, if the area around the through hole is made of a high brightness surface such as a steel plate surface, scratches and dents, welding spatter and oil adhesion may occur on the surface around the through hole due to work errors or inexperienced operators. Differences in reflected light depending on whether the material is plated or unplated, or the measurement light source on the surface around the through hole due to poor setting or construction of the workpiece, occurrence of surface inclination to the light receiving part, irradiation of the measurement light source Due to slight changes in angle, etc.
There was a problem in that brightness changes were sensitive around the through hole, making image reception unstable.

Another method for emphasizing the difference in brightness between the through hole and the surrounding area of the through hole is to reduce the brightness of the background of the through hole.

However, unless the workpiece is being measured in a darkroom, it is unexpectedly difficult to sufficiently darken only the background of the measurement location in a factory environment that receives general natural light. There are problems with this.

(d) Means for solving the problem This invention provides a measurement light source that emits light onto the surface of an object to be measured, and a measurement object that has a through hole formed therein. The light from the measurement light source is located on the opposite side, and the background is relatively dark compared to the reflected light that reflects the light from the measurement light source on the surface of the workpiece. In this light-receiving device for through-hole measurement, a lens with a shallow depth of field and focused on the surface of the object to be measured is attached to the light-receiving section, and a lens that is focused between the surface of the object to be measured and the background is attached. By providing a light-receiving device for through-hole measurement, which is characterized by providing a distance at which the amount of light received from the background is lower than that from the surface of the object to be measured.
This solves the problem of the installation location of the measurement light source, and also solves the problems of the conventional reflective through-hole measuring device.

(e) Production A measurement light source is projected onto the surface of the object to be measured.

Then, reflected light is generated on the surface of the object other than the area where the through hole is formed, and the through hole area is represented as a dark part of the background, and the light receiving section senses the difference in brightness between the through hole and the area around the through hole. At this time, a lens with a shallow depth of field and focused on the surface of the object to be measured is attached to the light receiving section.
In addition, since the lens does not focus on the surface of the object to be measured and the background, the amount of light received from the background is lower than that of the surface of the object to be measured. The difference in brightness between the two is emphasized, and the outline between the two becomes clear.

(F) Embodiment An explanation will be given with reference to FIG. 1 showing an embodiment of the present invention and FIG. 2 showing the state of use thereof.

(11) is the object to be measured. In this embodiment, the object (II) is an automobile monocoque body formed by processing unpainted steel plates on an automobile assembly line (12).

The object to be measured (11) is provided with a through hole (13) that is drilled for attaching other parts in a process prior to through hole measurement.

(14) is a factory facility in which an automobile assembly line (12) is installed, and (15) is a lighting window installed in the factory facility. (
16) is a light shielding plate, and the background (17) of the object to be measured (11) is
) to block natural light that shines directly on the area.

The extension (17) in this example consists of the inner side of the opposite side of the vehicle body.

(18) is a measurement light source. In this example, a highly condensed spot light is used as the light source for measurement, and the light source is 75W.
,, Use a herogen lamp, tungsten lamp, etc. with a value of 1000 (2) on the surface to be measured.

It is desirable that the measurement light source (18) has a stable light amount.

(19) is a light receiving section. The light receiving part (19) is connected to the object to be measured (
11) is installed on the same side as the measurement light source, and converts the manually input optical information into electrical signals.

In this embodiment, the light receiving section (19) consists of a CCD camera. There is a distance of 300 m on the side of the object to be measured (11) of the light receiving part (19).
A telephoto lens (19) a of about MF4 is fixed.

By attaching the telephoto lens (19)a, the light receiving section (19)
), the depth of field becomes shallow and the amount of light received is extremely low in out-of-focus areas.

In this example, the surface of the object to be measured (11) and the background (17)
This means that the depth of field is 0, as long as the distance is 75 mm or more.

Background (17), measurement light source (18), light receiving section (19),
A telephoto lens (19)a constitutes a light receiving device (1).

(20) is an image processing section which receives a signal input from the light receiving section (19), performs image processing, and displays a through hole image (A) on a display section (21) consisting of a CRT screen.

(22) is an image processing unit (20) similar to the display unit (21).
This is a judgment unit that receives signals from the Similar to the image processing signal, the determining unit (22) determines the shape, area, and shape of the desired reference through hole.
Alternatively, it also receives a reference signal from a reference signal generator (23) that stores the center of gravity position of the through-hole image (A).

To explain the operation of this embodiment, first, measurement light a (1g) is projected onto the area where the through hole (13) of the object to be measured (11) is formed and its surroundings.

The light intensity is about 1,000νX even on the surface to be measured, compared to the conventional 3.0
OOfl! Because it is low compared to
Even if there are dents, deformations, and surface inclinations, sensitive changes caused by these will be reduced.

The light intensity of the measurement light source (18) is lowered compared to the conventional example, and on the other hand, the background side of the object to be measured (11) is exposed to the background (17) of natural light.
) is simply blocked by the light blocking plate (16). Therefore, from the light receiving part (19) position, the area around the through hole that reflects the measurement light source (18) and the background appear as they are, so the difference in brightness between the dark part of the through hole (13) is smaller than in the conventional example. It disappears.

However, the light receiving section (19) has a telephoto lens (19)a that has a shallow depth of field and the amount of light received is extremely low in out-of-focus areas. The distance between the surfaces of the object to be measured (11) is greater than the depth of field at which the amount of light received from the background (17) is extremely reduced when the surface of the object to be measured (11) is focused. The focus of the lens is on the surface of the through hole (13) of the object to be measured (11). Therefore, the through hole (1
3) The difference in brightness between the surroundings and the background (17) through the through hole (13) is sensed by the light receiving unit (19) in a more emphasized manner than when using a standard lens. Also, since the depth of field is shallow, the light receiving part (19) is located between the background (17) and the object to be measured (11).
Even if a small amount of natural light enters the camera, it will have little effect on the image captured, except when direct light enters the camera.

Therefore, the light is received with a clear outline of the through hole (13), that is, with a clear outline of the image of the through hole (13).

Optical information received by the CCD camera of the light receiving section (19) is converted into an electrical signal and sent to the image processing section (20). The signal received by the image processing section (20) undergoes image processing and is transmitted as an image signal to the display section (21), where it is displayed as a through-hole image (A).

The signal from the image processing section (20) is simultaneously transmitted to the judgment section (22).
) But I accept it.

The received through-hole image information is transmitted from the reference signal generating section (23) after correcting the error in the diffusion of reflected light caused by the distance from the object to be measured (11) to the light receiving section (19). The shape, area, and center of gravity position of the through hole image (in this embodiment, the center of gravity position) are compared with the reference through hole information signal of , and it is determined whether the power is within the allowable range or not, and the suitability of the through hole is displayed on the display (
B). When determining the suitability of a formed through hole by comparing the positions of the centers of gravity of through hole images, as shown in FIG.
This is done by determining whether the positional deviation between the measured through-hole image (A) and the center of gravity 0 is within the error range.

According to the suitability display, workpieces in a disqualified state are removed.

Comparison Example 2 A 5mm f1.8 wide-angle lens, a 50mm f1.4 standard lens, and a 300mm f4 telephoto lens were each fixed to the tip of a CCD camera, and the monitor (display section) upper neck method, magnification, resolution (
δ) and depth of field (D).

■ Calculate magnification and resolution using the geometric imaging dimension calculation method.

In Fig. 4, X; Actual size x: Imaging dimension L detected by CCD camera:
Subject distance F: Focal length At this time, the relationship X=FX/L holds true.

The size (X') of the object displayed on the monitor (display unit) and its magnification after correction by the equipment are determined as follows.

X' - (Image size: X) X (Correction value) / (Effective image size)
(mm) Magnification = x'/X Resolution (δ) is determined as follows.

δ=1/((magnification) x (number of monitor pixels)/(monitor dimensions)) (mff+/pixels) ■ Calculation of depth of field In Figure 5, dl Backward depth of field d: Front field Depth d3: Depth of focus L: Subject distance δ: Allowable circle of confusion.

F: Focal length r: Aperture value Then, D: depth of field is determined by the following formula.

D=d, -d.

= F''L/(F'-(L-P)δf)-F2
L/(F2+(L-F)δf)(mm) Assuming that the distance between objects L = 700mm and the actual size of the object X = 6.5φ, with a 300mm f4 telephoto lens (δ = 0.03),
Depth of field=D is determined as follows.

D = 3Of)'X 700/(3(IQ'-(70
0-3(10)X Q,Q3X 4)-3[10”x
700/ (300” + (700-300) x
0.034×4) 0.75mm ■ Wide-angle lens Standard lenses are calculated in the same way and summarized below.

preferred.

(G) Effects of the Invention Therefore, in this invention, although the measurement light source and the light receiving part that receives the reflected light of the measurement light source are installed on the same side with respect to the workpiece, Since there is no need to make the surface particularly bright, it is effective in accurately measuring the shape and outline of a through hole drilled in a high-brightness workpiece, and it also eliminates the need to make the background particularly dark and to increase the difference in brightness. Therefore, there is also the effect that it is not necessary to completely shield the background portion of the through hole during measurement.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, FIG. 2 is a diagram of the same in use for a deaf person, FIGS. 3, 4, and 5 are diagrams of an embodiment, and FIG. 6 is a diagram of a conventional example. (1)...Light receiving device, (11)...River/object to be measured, (Work 3)...Through hole, (17)...River...Background, (18)... River/measurement light source, (19)...
- Light receiving section, (19) a...Telephoto lens. Patent applicant Central Jidosha Co., Ltd. Representative Patent Attorney
Tadashi Yasuhara 2nd Yasuhara
Masayoshi Hara Figure 3 Figure 4 Figure 5 Figure 6 'W+ q

Claims (3)

[Claims] (1) When a measurement light source that emits light onto the surface of the object to be measured and an object to be measured that has a through hole are installed, the measurement light source is located on the opposite side of the object to be measured, and the surface of the object is located on the opposite side of the object. In the light-receiving device for through-hole measurement, which consists of a background that is relatively dark compared to the reflected light that reflects light from the measurement light source, and a light-receiving section that detects the reflected light that is reflected on the surface of the workpiece, the light-receiving section is is equipped with a lens that has a shallow depth of field and focuses on the surface of the object to be measured, and since the lens cannot focus between the surface of the object and the background, the amount of light received from the background is smaller than that of the object to be measured. A light-receiving device for through-hole measurement, characterized by providing a distance that is lower than the surface. (2) Claim 1 in which the light receiving section is a CCD camera
A light receiving device for through-hole measurement as described in 1. (3) The light receiving device for through hole measurement according to claim 1 or 2, wherein the lens is a telephoto lens.