JPS6210379B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is an external appearance inspection of a spherical body in which defects on the surface of a spherical body are optically detected and electrically processed through a photoelectric conversion element to determine the presence or absence of defects that should be considered defective. Regarding equipment.

Generally, as a method for inspecting defects on the surface of a spherical body, light is projected onto the spherical surface in the form of a spot, and the reflected light is captured by a photoelectric conversion element. A method of scanning a surface is known, but devices that have put this method into practical use scan the surface to be inspected using sliding motion, which causes instability in scanning, and problems with the driving device. Problems include complexity, wear of the drive rollers, and time-consuming inspections.

Another conventional technique involves arranging a plurality of pairs of light emitters and light receivers made of optical fibers on the half circumference of the bulb to be inspected, and each light receiver is configured with an independent photoelectric conversion element and a processing discrimination circuit. There is an apparatus that inspects the entire surface of a sphere to be inspected by rotating the sphere to be inspected in a direction perpendicular to the direction in which the light receiving sections are arranged.

However, even in the above-mentioned conventional technology, if the size of each light receiving part is made smaller in order to improve detection accuracy, the number of photoelectric conversion elements and discrimination processing circuits will increase, making the device expensive and making adjustments more complicated. Moreover, due to the large aperture angle of the optical fiber, the receiver must be placed as close as possible to the surface of the spherical body in order to minimize the overlap of the fields of view of adjacent receivers; Another drawback was that the light-receiving part became dirty due to oil on the body surface.

This invention was made in order to eliminate the above-mentioned drawbacks.The spherical body to be inspected is rotated in one direction by a drive device, and a plurality of points on the light emitting part and the light receiving side are connected to the surface of the spherical body to be inspected. The imaging system and the photoelectric conversion element are arranged so that the reflected light from the spherical body to be inspected of the projection light emitted from the light projecting section forms an image on the surface of the photoelectric conversion element, and the output signal from the photoelectric conversion element is processed and judged. This is an external appearance inspection apparatus for a spherical body, characterized in that an electric circuit is provided to perform scanning of the spherical surface to be inspected in the direction of the rotational axis electrically, and scanning in the rotational direction is carried out mechanically.

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a steel ball which is a spherical body to be inspected, 21, 2
2 is a drive roller that rotates the steel ball 1;
The book drive rollers 21, 22 are driven in the same direction by the roller drive device 3. A stopper 4 for positioning the steel ball 1 is attached to the end face of the roller 21, and the steel ball 1 is positioned at a fixed position in the axial direction of the drive rollers 21, 22. 51,5
Reference numerals 2, 53, and 54 are imaging systems described in detail below, and four of them are used in this embodiment, and the fields of view of adjacent imaging systems overlap steel ball 1 with some overlap.
It has a field of view that extends over at least half of the circumference.
Reference numeral 6 denotes a light projecting section composed of optical fibers, which includes the intersection point of the rotational axis 10 of the steel ball 1 to be inspected and the surface of the steel ball 1, and extends around the half circumference AB of the arc on the surface of the steel ball 1.
(See Figure 2) Uniform light is projected over the area, and a relationship of regular reflection is maintained between each imaging system 51, 52, 53, and 54 and the center of field of view of the surface of the steel ball 1. The light source is provided by a lamp 7. Each imaging system 51, 52, 53, 5
Solid-state imaging array elements 81, 82, 83, and 84 as photoelectric conversion elements are arranged on the imaging plane 4, and 9 is a circuit for processing and determining signals obtained by the solid-state imaging array elements.

FIG. 2 shows the positional relationship between the steel ball 1 and each of the imaging systems 51, 52, 53, and 54 when the apparatus shown in FIG. 1 is viewed from the direction of arrow A. Each imaging system 51, 52,
53 and 54 are composed of microlenses (for example, self-occurring lenses manufactured by Nippon Sheet Glass Co., Ltd.) or ordinary lens systems, and each imaging system 51, 52, 5
3, 54 is at least half the circumference of the steel ball 1 on the meridian
While having an appropriate overlap △θ between the fields of view of adjacent imaging systems so that the field of view CD is larger than AB,
Viewing angle θ ₁ (CE), θ ₂ (FG), θ ₃ respectively
(HI) and θ ₄ (JD). Each imaging system 51, 5
The optical axes of the lenses 2, 53, and 54 pass through the viewing angle center points P ₁ , P ₂ , P ₃ , and P ₄ , and pass through the viewing angle center points P ₁ , P ₂ , P ₃ , P ₄ and the steel With respect to the plane containing the rotation axis 10 of the sphere 1, the center point P ₁ of each viewing angle,
It is located symmetrically with the incident optical axis passing through P ₂ , P ₃ , and P ₄ and at a position of regular reflection. In the optical system arranged in this way, the imaging plane of each imaging system 51, 52, 53, 54 has a surface of the steel ball 1 corresponding to each field of view.
Images of CE, FG, HI, and JD are formed. Therefore, the waveform shown in FIG. 3a is obtained as the electrical output signal of each solid-state imaging array element 81, 82, 83, 84 arranged on each imaging plane. The start signal to drive each solid-state imaging array element 81, 82, 83, 84 is transmitted to each solid-state imaging array element 81, 82, 84.
When the scanning time Ts is 3,84, and the number n of solid-state imaging array elements (n=4 in this embodiment), each solid-state imaging array element 81, 82 is shifted by a time Ts/n using a counter, for example. , 83 and 84 of the images corresponding to each field of view on the surface of the steel ball 1 become signals that do not overlap in time (FIG. 3b), and are input to the processing discrimination circuit 9. As shown in FIG. This makes it possible to perform time-division processing, and the subsequent processing circuits are connected to each solid-state imaging array element 81, 82, 83, 8.
It can be configured with one circuit common to all four circuits, thereby eliminating the cost increase and complexity of the device.

In the first comparison circuit 96, the reference signal set in advance in the reference signal setter 98 or each solid-state image pickup array element 81, 82, 83, 84 from several scans ago is used.
and the reference signal generated based on the envelope of the output signal of each solid-state imaging array element 81, 82, 83, 8.
The width of the defect in the scanning direction is detected by comparing the width of the defect in the scanning direction by comparing the width of the defect in the scanning direction with the output signal of No. The second comparing circuit 97 compares the set value with the set value, and if it is equal to or higher than the set value, it is determined to be defective, and a defective discharge gate (not shown) is activated.

Here, each solid-state imaging array element 81, 82, 8
The resolution Dh in the array direction detected at 3.84 is expressed by the following equation.

Dh=a/Mcos=−θi/2≦θ≦θi/2i=1
, 2,...n, where a is the solid-state imaging array element 81, 82,
The length of 1 bit in the scanning direction of 83 and 84, and M is the magnification of the imaging systems 51, 52, 53, and 54.

In addition, each solid-state imaging array element 81, 82, 8
The resolution Dv in the vertical direction to 3.84 is expressed by the following equation.

Dv=pvn/f where P: Number of bits of the solid-state imaging array v: Circumferential velocity of the steel ball f: Clock frequency of the solid-state imaging array n: Number of solid-state imaging array elements Time required to measure the entire surface of the steel ball T ₁ is T ₁ = xD/v ₁ D: Diameter of the steel ball V ₁ : Peripheral speed of the steel ball according to this method On the other hand, the time required to measure the entire surface of the steel ball using the conventional skew method described above T ₂ is T ₂ =xDN/v ₂ N: Number of revolutions required to scan the entire surface of the steel ball v ₂ : Circumferential speed of the steel ball using the skew method N=180°/: Skew angle Therefore, measurement time T ₁ = T ₂ , the circumferential speed of the ball to be inspected in the device of the present invention is only 1/N of the circumferential speed in the skew method of the prior art, which reduces the stability of the ball to be inspected and the wear of the drive roll. superior to conventional technology.

Further, if the circumferential velocity v ₁ =v ₂ , the measurement time in the apparatus of the present invention is 1/N of the measurement time in the skew method of the prior art, and high-speed inspection is possible.

Another embodiment of the present invention shown below is an appearance inspection device for inspecting the surface of a steel ball in the same manner as the above embodiment, and the steel ball driving device and light projecting unit are the same.
On the light receiving section side, imaging systems 51, 52, 53, 5
By providing image guides 111, 112, 113, and 114 between the solid-state imaging array element 8 and the solid-state imaging array element 8, only one solid-state imaging array element 8 is required, and the processing and discrimination of signals extracted from the solid-state imaging array element 8 can be performed. The difference is that the circuit can be easily constructed. In this second embodiment, one solid-state imaging array element is used as described above, and a signal can be input directly to the first comparator 96 via the buffer circuit 91. 97 is a second comparator, 98 is a reference signal setting device, and 99 is a setting device in which the size of defect width to be determined as defective is set. In this device,
While rotating the steel ball 1, a light beam is projected onto the surface of the steel ball 1 from the light projection unit 6, and the reflected light from the surface of the steel ball 1 is captured by the imaging systems 51, 52, 53, and 54, and the imaging systems 51, The reflected light captured by 52, 53, and 54 is imaged on the solid-state imaging array element surface 8 via image guides 111, 112, 113, and 114. The signal converted into an electrical signal by the solid-state imaging array element 8 is inputted to a buffer circuit 91 and further inputted to each comparator, thereby detecting a signal due to a defect and detecting the defect. Judgment is made based on size.

Comparing the above device with the device of the above-described embodiment, the circuit for processing and determining the signal obtained by the solid-state imaging array element is simpler and therefore less expensive.

As described above, according to the present invention, when scanning the surface of the spherical body to be inspected, skew is not required, so instability caused by skew of the spherical body to be inspected,
There is no problem of drive roller wear, the roller drive mechanism is simplified, and high-speed, high-precision inspection is possible. In addition, in this invention, the light emitting part and the light receiving part can be positioned with an appropriate distance from the surface of the spherical body to be inspected, so that the problem of oil droplets from the spherical surface, which was a drawback of conventional devices, can be avoided. There is no need to worry about contamination of the light receiving section. Furthermore, there is no fear that the spherical body to be inspected will come into contact with the light projecting section or the light receiving section, and moreover, highly accurate inspection is possible.

Furthermore, by processing signals from a plurality of solid-state imaging array elements with one processing/discriminating circuit, highly accurate detection can be achieved at low cost.

Furthermore, when an image guide is used between the imaging system and the photoelectric conversion element, the detection processing circuit becomes simpler and the cost becomes lower.

Another advantage is that scanning of the projected light is not required and the inspection time is short.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the positional relationship between the spherical body to be inspected and the imaging system when the apparatus in FIG. 1 is viewed from the direction of arrow A. FIG. 3a is a diagram showing the relationship between the field of view and the output signal of the solid-state imaging array element in the device shown in FIG. 1, and FIG. FIG. 4 is a time chart showing the phase relationship of output signals between elements, FIG. 4 is a signal processing circuit diagram in the device shown in FIG. 1, and FIG. 5 is a schematic diagram of a device showing another embodiment of the present invention. . Explanation of the symbols: 1 is a spherical body to be inspected; 21, 22 are drive rollers; 51, 52, 53, 54 are imaging systems;
6 is a light projecting unit; 81, 82, 83, 84 are photoelectric conversion elements; 9 is a signal processing/discrimination circuit; 91, 92, 9
3 and 94 are buffer circuits, 95 is a multiplexer, 96 is a first comparator, 97 is a second comparator, and 111, 112, 113, and 114 are image guides.

Claims (1)

[Scope of Claims] 1. The spherical body to be inspected is given the necessary rotation, the spherical surface to be inspected is irradiated with a light beam from a light projector, the reflected light is converted into an electric signal by a photoelectric conversion element, and the electric signal is converted into an electric signal. In a visual inspection device that inspects defects on the surface of a spherical body to be inspected by inputting the spherical body to a discrimination processing circuit, the spherical body to be inspected is rotated around a predetermined rotation axis, and the rotation axis of the spherical body to be inspected is A light projecting section provided at a position capable of projecting a uniform amount of light over half a circumference AB of an arc on the surface of the spherical object to be inspected, including the intersection with the surface of the spherical object to be inspected, and a spherical object to be inspected from the light projecting section. a plurality of imaging systems arranged so that the viewing angles have an appropriate overlap (Δθ) at positions where the reflected light of the projection light irradiated over half a circumference AB of the circular arc on the surface can be received; It consists of a photoelectric conversion element placed on each image forming plane of the imaging system and an electric circuit that processes and discriminates the electrical signals from the photoelectric conversion element. An apparatus for inspecting the appearance of a spherical body, characterized in that scanning in the rotational direction is performed mechanically. 2. In the device according to claim 1,
The processing discrimination circuit includes a circuit for temporally shifting a start signal for driving a plurality of photoelectric conversion elements, and a multiplexer for time-divisionally processing the output signal of the photoelectric conversion element, A spherical body appearance inspection device in which signal processing and discrimination are performed by a single processing and discrimination circuit for the conversion element. 3. In the device according to claim 1,
Appearance inspection of a spherical body in which one end of an image guide made of optical fiber is arranged on each of the imaging surfaces of a plurality of imaging systems, and the other end of the image guide is arranged on a single photoelectric conversion element. Device.