JPS6361948A - Surface shape inspection instrument - Google Patents

Abstract

PURPOSE:To inspect the projection and recess state of the surface of a body to be inspected without any environment restrictions by irradiating the body to be inspected with a detection wave signal such as an ultrasonic wave, and receiving its reflected wave by a wave receiver group and imaging the surface shape of the body to be inspected. CONSTITUTION:This device consists of a wave transmitter 2, the receiver group 3, an oscillator 4, and a CPU9, etc. Then when the detection wave signal such as an ultrasonic wave is sent out of the transmitter 2 to the body 1 to be inspected, the signal is reflected by the surface of the body 1 to be inspected and received by respective receivers in the receiver group 3. The amplitude and phase of each received signal of the receiver group 3 are found and supplied as hologram data to an arithmetic processing part. The same operation is carried out as to detection wave signals of all frequencies to generate hologram data as to all combinations of the all frequencies and all wave reception positions. The arithmetic processing part performs specific arithmetic operation with the supplied hologram data, and consequently the surface shape of the body 1 to be inspected is imaged. Then this body image is matched with images which are registered previously and the surface shape of the body 1 to be inspected is judged from whether both images coincide with each other or not.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention involves imaging an object to be inspected and then comparing this image with a pre-registered image to inspect the surface shape of the object. In particular, the present invention relates to a surface shape inspection device used in The present invention relates to a surface shape inspection apparatus for performing predetermined arithmetic processing based on the transfer signal to image the surface shape of an object to be inspected.

<Prior Art> Conventionally, as this type of surface shape inspection device, there is one using an optical imaging device. This device images an object to be inspected from directly above with a television camera, and compares the image with a pre-registered image to inspect the surface shape of the object.

<Problems to be Solved by the Invention> However, with this type of optical imaging device, only a flat image of the object to be inspected viewed from directly above can be obtained; In addition, optical imaging devices are susceptible to optical constraints such as external lighting and object color, and there are also problems such as inspection being difficult in adverse environments where dust is generated. .

In order to solve the above problem, this invention irradiates the object to be inspected with a detection wave signal such as an ultrasonic wave and receives the reflected wave by a group of receivers to visualize the surface shape of the object. ,
It is an object of the present invention to provide a novel surface shape inspection device that can inspect the uneven state of the surface of an object to be inspected with almost no restrictions from the environment.

Means for Solving the Problems> In order to achieve the above object, the surface shape inspection apparatus of the present invention includes a wave transmitter and a wave transmitter for transmitting a plurality of types of detection wave signals having different frequencies to the surface of an object to be inspected. , a wave receiver group consisting of a plurality of wave receivers arranged for receiving reflected waves from the object to be inspected, and a predetermined amplitude and phase of multiple types of received waves No. 13 obtained with this wave receiver group. It was decided to include an arithmetic processing section that executes the arithmetic operations and visualizes the surface shape of the object to be inspected.

<Operation> When a detection wave signal such as an ultrasonic wave is sent from a wave transmitter toward an object to be inspected, this detection wave signal is reflected from the surface of the object to be inspected and is received by each receiver in the receiver group. be done. The amplitude and phase of the received signal at this receiver group are determined,
It is given to the arithmetic processing unit as hologram data. When the same operation is performed for the detected wave signals of all frequencies,
Hologram data is generated for combinations of all frequencies and all wave reception positions. The arithmetic processing section executes a predetermined arithmetic operation using the provided hologram data, thereby visualizing the surface shape (unevenness) of the object to be inspected.

However, this object image is then compared with the pre-registered image,
The surface shape of the object to be inspected is determined based on whether or not both images match.

<Embodiment> FIG. 1 shows an example of the overall configuration of a surface shape inspection apparatus according to an embodiment of the present invention. This surface shape inspection device is for visualizing the surface shape of an object to be inspected 1 in the Z dimension and inspecting whether it has a predetermined shape or not. Receiver group 31 oscillator 4. Power amplifier5. Amplification circuit 6
゜Detection circuit 7. A/D converter 8 and computer 9
etc. are included in the structure.

In the case of this embodiment, the oscillator 4 generates L types of ultrasonic signals (where L is an integer of 2 or more) whose frequency differences are equally spaced. The transmitter 2 is placed at the center of the group of receivers 3, receives an ultrasonic signal from the oscillator 4 via the power amplifier 5, and irradiates the surface of the object 1 from directly above.

The wave receiver group 3 is for receiving the ultrasonic signal reflected from the surface of the object 1 to be inspected, and in the illustrated example, -
M number of receivers R8 (M is an integer of 2 or more) on a straight line
, R1,...+ R, -.

are arranged at equal intervals.

The ultrasonic signal received by the wave receiver group 3 is amplified by an amplifier circuit 6, its amplitude and phase are measured by a detection circuit 7, and converted into a digital signal by an A/D converter 8 as hologram data. The data is then stored in the memory 10 of the computer 9.

Such hologram data is measured for combinations of all types of frequencies and all positions of the wave receiver group 3, and the CPU II, which is the control main body of the computer 9, executes predetermined calculations based on these hologram data. An image of the surface shape of the object to be inspected 1 is reproduced.

FIG. 2 shows the reproduced image 13, in which the surface shape of the object 1 to be inspected along the arrangement direction of the wave receiver group 3 (the shape along the thick line 12 in FIG. 1) is reproduced exactly as it is uneven.

In addition, the CPU 1 compares the obtained reproduced image of the object to be inspected 1 with a registered image registered in advance in the memory 10, and determines whether or not the two images match or not to damage the surface of the object to be inspected. Determine whether or not foreign matter is present. Note that matching between the reproduced image and the registered image is performed using a pattern matching algorithm used in conventional optical inspection devices.

By the way, the hologram data is two-dimensional LXM data, but the frequency differences of the types of ultrasonic signals irradiated to the object 1 to be inspected are at equal intervals, and the wave receiver R0°R1 in the wave receiver group 3 ,...+ RFI-1 is arranged at equal intervals, and when the object 1 to be inspected is in the Fresnel region, each two-dimensional direction of the hologram data (
12° direction) is each two-dimensional direction (z.

(in each direction of X) and form a Fourier transform pair, respectively.

Therefore, by performing two-dimensional Fourier transformation processing on the obtained hologram data, a two-dimensional image of the object to be inspected 1 can be obtained.

Now assuming the X coordinate shown in Fig. 3, and considering the case where an ultrasonic signal with a frequency of ω is irradiated from the coordinate center 0 to the object region, this ultrasonic signal will be reflected at the reflection point Q within the object region.
(xo, zo), the X coordinate position x,
The wave is received by In this case, the received ultrasonic signal htf
fi is the distance between position X1 and reflection point Q, R, . , when the distance between the coordinate center 0 and the reflection point Q is R6°, it is expressed as the following equation 0.

+R,. ) l dx dy...■Measure the above signals at all frequencies and all receiving positions, and then
The two-dimensional image is reproduced according to the reproduction formula shown in the following equation.

(ROT+Rnv) ) l 2-■ In the above formula, R
FIT indicates the distance between the position X7 and the image reproduction point T, and Ro□ indicates the distance between the coordinate center 0 and the image reproduction point T, respectively. Further, C is a constant.

By the way, in the surface shape inspection apparatus in this embodiment, the frequency differences of the above types of ultrasonic signals irradiated to the inspection object 1 are at equal intervals, and the arrangement intervals of the wave receivers in the wave receiver group 3 are also at equal intervals. Therefore, ωLIXN in the above equation can be expressed as the following equation 00.

x, -p, -m...■ (However, m=o, 1, 2..., t1) (However, l
=0.12. , -0. L-1) In the above formula, px is the interval in the X direction between each receiving point, and fc is the fundamental frequency.

Furthermore, assuming that the object region is in the Fresnel region, the following Fresnel approximation is introduced.

R,,=X By substituting the above equation 00 into the above equation 0, the following equation 0 is obtained.

1 (x, z) = 1ΣΣFLLn'eXp (j-Co -x,
” ) −exp (j−C+ ・zfL)
・exp (j-Cx ・xx,) 12exp
(j-cz ・xx,)R= l F (ht*
') 12...■In the above formula, Go, C+,
Cz is a proportionality constant.

Furthermore, in the above equation, h′ is as shown in the following equation 0, which represents the correction calculation process of hologram data depending on the position of the receiving wave element.

h+*'=htn・eXp(3-Go・Xn"
)...■ Thus, in the above equation 0, the right side represents the Fourier transform of h LM', and if the obtained hologram data is corrected and this data is subjected to two-dimensional FFT with respect to 13m, the object It turns out that the statue can be regenerated.

FIG. 4 shows a procedure for inspecting the surface shape of the object 1 to be inspected.

First, in step 1 (indicated by rSTIJ in the figure), the CPU 1 operates the oscillator 5 to generate an ultrasonic signal of a certain frequency, drives the power amplifier 5, and transmits the wave transmitter 2.
The ultrasonic signal is then sent toward the object 1 to be inspected. This ultrasonic signal is reflected by the surface of the object to be inspected l, and this reflected wave is transmitted to each receiver R,, R,, . . . of the receiver group 3.

The wave is received at RA-1.

The CPU 1 performs similar control for ultrasonic signals of all other frequencies, and hologram data is generated for the alignment of all frequencies and all wave reception positions.

This hologram data is stored in the memory 10 of the computer 9, and is subjected to correction calculations such as correction of transmitting/receiving wave element characteristics and focal position correction as necessary. Note that the hologram data is expressed as h (m, !2), where l is the frequency combination direction and m is the combination direction of the X coordinates of the wave receiver group 3.

Next, in step 2, the CPU 1 first performs Fourier transform processing on the hologram data h (m,
, Convert the X coordinate into two coordinates. The hologram data obtained in this way is then subjected to Fourier transformation processing in the m direction, thereby converting the m coordinate to the X coordinate, and finally a two-dimensional object image displayed at (x, z). I is obtained.

In the next step 3, the CPU II stores the object image in the memory 1 based on the pattern matching algorithm.
0, and it is determined whether or not there are scratches or foreign matter on the surface of the inspection object 1 based on whether the two images match or not.

In addition, the ultrasonic waves in the above embodiments may be so-called Chi-F waves that continuously change their frequency.
Furthermore, it is also possible to use electromagnetic waves instead of ultrasonic waves as detection waves.

Further, in the above embodiment, a one-dimensional array of a plurality of wave receivers is used as the wave receiver group 3, but the present invention is not limited to this, and a two-dimensional array of a plurality of wave receivers may also be used. is possible. In this case, the reproduced image of the object to be inspected 1 is three-dimensional, but the surface shape of the object to be inspected 1 can be inspected by performing the same operation 111 as described above.

<Effects of the Invention> As described above, the present invention is capable of irradiating a detection wave signal such as an ultrasonic wave onto an object to be inspected, and receiving the reflected wave by a group of receivers to visualize the surface shape of the object to be inspected. Because of this, it is not subject to environmental constraints like conventional optical imaging devices, and it also has the remarkable effects of achieving the purpose of the invention, such as being able to inspect Vi and even the unevenness of the surface of the object to be inspected. play.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a surface shape inspection apparatus according to an embodiment of the present invention, Fig. 2 is an explanatory drawing showing an example of a reproduced image, and Fig. 3 is an explanatory drawing showing the operation of transmitting and receiving ultrasonic waves. figure,
FIG. 4 is a flowchart showing an inspection procedure using an example of the apparatus of the present invention.

Claims (5)

[Claims] (1) A surface shape inspection device for inspecting the surface shape of an object to be inspected by imaging the object to be inspected and then comparing this image with a pre-registered image, the surface of the object to be inspected. a wave receiver for transmitting multiple types of detection wave signals with different frequencies to the target object; a wave receiver group consisting of a plurality of wave receivers for receiving reflected waves from the object to be inspected; A surface shape inspection apparatus comprising: a calculation processing section that performs predetermined calculations on the amplitude and phase of multiple types of received signals obtained in groups to visualize the surface shape of an object to be inspected. (2) The surface shape inspection device according to claim 1, wherein the detected wave signal is an ultrasonic signal. (3) The surface shape inspection apparatus according to claim 1, wherein the wave transmitter transmits a plurality of types of detection wave signals having frequency differences at equal intervals. (4) The surface shape inspection apparatus according to claim 1, wherein the wave receiving element group is constructed by arranging a plurality of wave receiving elements in a line. (5) The surface shape inspection apparatus according to claim 1, wherein the arithmetic processing section is a computer whose main control is a CPU.