JP2005331312A - Optical pinhole inspection device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pinhole inspection device characterized by detecting a fine pinhole smaller than one pixel size, for detecting the fine pinhole inexpensively at high speed for the whole sheet surface. <P>SOLUTION: This device is constituted of a CCD camera 1 with a built-in CCD 10; a lens 2 to be mounted on the CCD camera 1; and a transmitted illumination 3 arranged on the opposite side of the CCD camera 1 relative to a sheet 9 to be inspected, for emitting a prescribed quantity of light. An image is acquired, wherein transmitted light 3b through a pinhole 9b is greatly emphasized compared with transmitted light 3d other than the light 3b through the pinhole 9b or reflected light 3e, and one pixel or more is reflected brightly by the transmitted light 3b through the pinhole 9b which is smaller than the area size of one pixel. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pinhole inspection apparatus and method for detecting the presence and number of minute pinholes generated in a thin sheet that transmits strong light, such as a ceramic green sheet or a printed wiring board.

  Conventionally, when a pinhole is detected by image processing using an optical pinhole inspection apparatus, when the pinhole image 9a is formed on the CCD 10 as shown in FIG. It was larger than the area size of the cell 10a. In general, the lens is determined so that the area of the minimum pinhole image 9a to be detected is 4 or more cells of the CCD, the image is taken, and image processing is performed to detect the pinhole. It was.

  In addition, as an optical pinhole inspection device, as shown in FIG. 7, two light source devices 3 that respectively irradiate light from two directions, and a glass window 6 are provided on the light irradiation surface of the light source device 3. A dark box 5, a diffusion plate 4 provided on the light source device 3 side of the sheet 9 to be inspected closely attached to the outside of the glass window 6, a CCD camera 1 housed in the dark box 5, and a tip of the CCD camera 1. The lens 2 was mounted, a quadrangular prism mirror 7 installed between the CCD camera 1 and the glass window 6, and an image processing device 8 connected to the CCD camera 1. The light emitted from the light source device 3 is diffused by the diffusion plate 4 and passes through the pinholes of the sheet 9 to be inspected. Some are directly reflected on the four mirrors of the quadrangular prism mirror 7 and the CCD camera. 1 is incident. The video signal from the CCD camera 1 is input to the image processing device 8 to automatically detect pinholes having a pinhole diameter smaller than the sheet thickness and having directionality.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP-A-6-222016

  However, the conventional configuration has a problem that a pinhole having a size smaller than one pixel size cannot be detected on an image scale. In order to detect a minute pinhole, the magnification of the lens was increased and an enlarged image with one pixel size smaller than the pinhole was captured and detected. In order to detect a wide area, it is necessary to scan the inspection area, which causes an expensive apparatus cost and a long inspection time. In particular, when inspecting pinholes on sheets that are thin enough to transmit light as a whole, the difference in the intensity of light passing through the pinholes and light passing through the sheets is small, so the entire image Became brighter and had the problem that pinholes could not be inspected.

  The present invention is intended to solve the above-described problem, and can detect a pinhole of one pixel size or less. As a result, an object of the present invention is to provide an optical pinhole inspection apparatus that detects fine pinholes on the entire surface of a sheet at low cost and at high speed.

  In order to achieve the above object, the present invention has the following configuration.

  The invention according to claim 1 of the present invention is particularly suitable for a CCD camera in which an area size of one pixel is larger than an area size of a pinhole to be detected on an image scale, a lens attached to the CCD camera, and a sheet to be inspected. If the sheet to be inspected is a light-shielding body, the brightness of the pinhole portion is increased as the amount of transmitted illumination is increased. Compared to the brightness around the hole, the brightness can be increased dramatically, and an image can be obtained in which one or more pixels are brightly reflected by the light entering the lens through a pinhole of one pixel size or less. The effect that a pinhole smaller than the area size can be detected is obtained.

  According to the second aspect of the present invention, the reflected light on the imaging surface side surface of the sheet to be inspected due to disturbance light is provided by a configuration in which a dark box for preventing disturbance light from being applied to the imaging surface side of the inspection sheet is provided. Since only the brightness of the pinhole portion can be stably increased even for a mirror-inspected sheet with high reflectivity or a sheet to be inspected with a bright color, a single pixel can be stably processed by image processing. The effect that a pinhole smaller than the area size can be detected is obtained.

  In the invention according to claim 3 of the present invention, in particular, since the lens is provided with an aperture adjustment function, the aperture of the lens can be opened to enhance the light incident on the CCD. In this state, the brightness of the pinhole portion can be increased, and an effect of detecting a pinhole smaller than the area size of one pixel can be obtained by image processing.

  In the invention according to claim 4 of the present invention, in particular, in the inspected sheet that is thin enough to transmit strong diffused light or the inspected sheet that is light in color due to the configuration using uniform parallel light for transmitted illumination, The brightness of the hole can be dramatically increased compared to the brightness around the pinhole, and the light entering the lens through a pinhole of one pixel size or less can be used to obtain an image that is brighter than one pixel. The effect of being able to detect a pinhole smaller than the area size of one pixel is obtained by image processing.

  The invention according to claim 5 of the present invention is particularly inexpensive due to the configuration in which the uniform parallel light of the transmitted illumination is formed by installing the diffused light surface illumination at a position away from the inspection sheet by a certain distance or more. Realizes uniform quasi-parallel light and raises the brightness of the pinhole part significantly compared to the brightness around the pinhole part in the thin or light-colored inspection sheet that transmits strong diffused light In addition, the effect of detecting a pinhole smaller than the area size of one pixel can be obtained by image processing.

  In the invention according to claim 6 of the present invention, in particular, two pieces of uniform parallel light of transmitted illumination are overlapped with a viewing angle adjusting film utilizing the principle of the blind so that the direction of the blind louver is perpendicular. The structure formed by inserting between the sheet to be inspected and the diffused light transmission illumination in a state is inexpensive and small, and realizes uniform quasi-parallel light and is thin enough to transmit strong diffused light In the inspected sheet or inferior color inspected sheet, the brightness of the pinhole part can be significantly increased compared to the brightness around the pinhole part, and a pinhole smaller than the area size of one pixel can be detected by image processing. The effect is obtained.

  According to the seventh aspect of the present invention, in particular, a predetermined amount of light is emitted from the transmitted illumination disposed on the opposite side of the CCD camera with respect to the inspection sheet, and is larger than the area size of the pinhole to be detected on the image scale. By detecting the pinhole by receiving the light passing through the pinhole at the pixel, the brightness of the pinhole part is significantly increased compared to the brightness around the pinhole part in the sheet to be inspected. It is possible to obtain an image in which one or more pixels are brightly reflected by light entering the lens through the pinhole, and an effect that a pinhole smaller than the area size of one pixel can be detected by image processing can be obtained.

  The optical pinhole inspection apparatus and method according to the present invention can increase the brightness of a pinhole part as compared with the brightness around the pinhole part, so that even light entering a lens through a pinhole of one pixel size or less can be used. It is possible to obtain an image in which pixels or more are captured brightly, and it is possible to detect a pinhole smaller than the area size of one pixel by image processing. As a result, there is an effect that a fine pinhole can be detected at a low speed and at a high speed even for a large sheet.

(Embodiment 1)
Hereinafter, the first to fourth aspects of the present invention will be described with reference to the first embodiment.

  FIG. 1 is a schematic configuration diagram showing an example of an optical pinhole inspection apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a principle diagram of the optical pinhole inspection apparatus.

  In addition, about the structural member demonstrated by the prior art, the same code | symbol is provided and detailed description is abbreviate | omitted.

1 and 2, the optical pinhole inspection apparatus according to the first embodiment includes a CCD camera 1 having a built-in CCD 10, a lens 2 having a diaphragm adjusting function 2b attached to the CCD camera 1, and a sheet to be inspected. 9 includes a transmission illumination 3 that emits a predetermined amount of light disposed on the side opposite to the CCD camera 1 and a dark box 5 disposed on the imaging surface side of the sheet 9 to be inspected.
The light 3a emitted from the transmitted illumination 3 passes through the pinhole 9b of the sheet 9 to be inspected, and the light 3b that has passed through the pinhole 9b enters the CCD camera 1 through the lens 2 and forms an image on the CCD 10. .

  In general, in the operation of the CCD, light received by each cell is converted into electric charge and stored as needed, and the amount of electric charge stored in each cell is sequentially transferred as a video signal at regular intervals. At this time, the charge amount Q accumulated in the CCD1 cell 10a is proportional to the accumulated light amount L received by the CCD1 cell 10a. The accumulated light amount L includes the light receiving area S of the CCD1 cell, the light amount Ls per unit area, and the accumulation time T. Therefore, it can be expressed by the following formula 1.

Q = α × L
= Α × β × S × Ls × T (Formula 1)
For this reason, as shown in FIG. 2A, when a pinhole image 9a is formed on the CCD 10, if there is a transmissive illumination 3 that emits a predetermined amount of light, it is larger than the CCD 1 cell 10a shown in FIG. 2B. The amount of charge (FIG. 2 (d)) accumulated in the CCD1 cell 10a for a certain time T by the light 3b having a certain intensity that has passed through the pinhole 9b and the pinhole 9b smaller than the CCD1 cell 10a shown in FIG. The amount of electric charge (FIG. 2 (e)) accumulated in the CCD 1 cell 10a for a certain time T can be made equal to the strong light 3b that has passed. Therefore, it is possible to obtain an image in which one or more pixels are brightly reflected by light entering the lens through a pinhole 9b smaller than the area size of one pixel, and detect a pinhole 9b smaller than the area size of one pixel by image processing. it can.

  Further, as shown in FIG. 1, by installing the dark box 5, it is possible to cut the reflected light 3 e due to disturbing light hitting the imaging surface side surface of the sheet 9 to be inspected. The CCD 10 can accumulate only 9b of light, and pinholes 9b smaller than the area size of one pixel can be detected stably.

  Further, as shown in FIG. 1, by opening the aperture adjustment function 2b built in the lens 2, even if the intensity of the light 3b that has passed through the pinhole 9b is the same, it passes through the lens aperture adjustment function 2b and hits the CCD. Since the light 3c can be strengthened, the CCD 10 can accumulate the light from the pinhole 9b with the minimum light 3a of the transmitted illumination 3, and the pinhole 9b smaller than the area size of one pixel can be detected.

  Further, in FIG. 1, when the inspected sheet 9 having a thickness and a color that are thin enough to transmit strong diffused light is irradiated on the transmitted illumination 3 using illumination that emits uniform parallel light, Since the diffusion of light inside the inspection sheet 9 is suppressed, the light 3b passing through the pinhole 9b is made much stronger than the light 3d diffused and transmitted inside the inspection sheet 9 around the pinhole portion. It is possible to obtain an image in which one or more pixels of the CCD 10 are brightly reflected by the light entering the lens 2 through the pinhole 9b of one pixel size or less, and a pinhole smaller than the area size of one pixel by image processing. Can be detected.

(Embodiment 2)
Next, the second aspect of the present invention, particularly the invention described in claim 5, will be described.

  FIG. 3 is a schematic configuration diagram showing an example of the optical pinhole inspection apparatus according to the second embodiment of the present invention.

  In addition, the same code | symbol is provided about the structural member demonstrated in FIG. 1, and detailed description is abbreviate | omitted.

  In FIG. 3, the optical pinhole inspection apparatus according to the second embodiment is configured such that the transmitted illumination 3 that emits a predetermined amount of light disposed on the side opposite to the CCD camera 1 is disposed at a certain distance from the inspection sheet 9. By disposing the above-described positions away from each other, the optical axis angle θ of the light radiated from each light emitting point of the transmitted illumination 3 to each point of the sheet 9 to be inspected becomes small, and the pseudo parallel light 3a can be easily and inexpensively produced. Can be made. Using this quasi-parallel light 3a, it is possible to obtain an image in which a pinhole 9b having a size of one pixel or less is brightly reflected even on a sheet 9 to be inspected whose thickness and color are thin enough to transmit strong diffused light. By processing, a pinhole smaller than the area size of one pixel can be detected.

(Embodiment 3)
Next, the third aspect of the present invention will be described with reference to the sixth aspect of the present invention.

  FIG. 4 is a schematic configuration diagram showing an example of an optical pinhole inspection apparatus according to Embodiment 3 of the present invention, and FIG. 5 is a principle diagram of a viewing angle adjustment film.

  In addition, about the structural member demonstrated by the prior art, the same code | symbol is provided and detailed description is abbreviate | omitted.

  5A, the viewing angle adjusting film 11 has a blind structure in which a large number of louvers 12 are arranged in the same direction, and the light transmittance is about 75 in the vertical direction as shown in FIG. 5B. %, It becomes almost 0% above ± 30 ° from the vertical direction, and the visible angle is limited to within ± 30 °. When two viewing angle adjusting films 11 are overlapped so that the direction of the blind louver is perpendicular, the viewing angle is limited both in the vertical direction and in the horizontal direction.

  In FIG. 4, the optical pinhole inspection apparatus according to the third embodiment has two viewing angle adjustment films 11 utilizing the principle of blinds, in a state in which the directions of the blind louvers are superposed. By inserting between the inspected sheet 9 and the diffused light transmission illumination 3, the optical axis angle θ of the light radiated from each light emitting point of the transmitted illumination 3 to each point of the inspected sheet 9 becomes small. Therefore, it is not necessary to separate the inspection sheet 9 and the transmitted illumination 3 from each other by a certain distance, the transmitted illumination 3 can be reduced in size, and pseudo uniform parallel light 3a can be produced. Using this quasi-parallel light 3a, it is possible to obtain an image in which a pinhole 9b having a size of one pixel or less is brightly reflected even on a sheet 9 to be inspected whose thickness and color are thin enough to transmit strong diffused light. By processing, a pinhole smaller than the area size of one pixel can be detected.

  The optical pinhole inspection apparatus according to the present invention increases the brightness of the pinhole part as compared with the brightness around the pinhole part, so that even if the light enters the lens through a pinhole of one pixel size or less, it is one pixel or more. Can be obtained, and a pinhole smaller than the area size of one pixel can be detected by image processing. As a result, it has the effect of being able to detect fine pinholes inexpensively and at high speed even for large sheets, and the pin that detects the presence or number of minute pinholes that occur in thin sheets that transmit strong light Useful for applications such as hall inspection.

1 is a schematic configuration diagram of an optical pinhole inspection apparatus according to Embodiment 1 of the present invention. The principle diagram of optical pinhole inspection equipment Schematic configuration diagram of an optical pinhole inspection apparatus in Embodiment 2 of the present invention Schematic configuration diagram of an optical pinhole inspection apparatus in Embodiment 3 of the present invention Same as above, view angle adjustment film Illustration of conventional pinhole size that can be detected Schematic configuration diagram of a conventional optical pinhole inspection device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 CCD camera 2 Lens 2b Aperture adjustment function 3 Light source device or transmission illumination 3a Light of transmission illumination 3b Light passing through pinhole 3c Light hitting CCD 3d Light diffusing inside sheet and transmitting through sheet 3e Reflection of sheet surface to be inspected Light 4 Diffuser 5 Dark box 6 Glass window 7 Square prism mirror 8 Image processing device 9 Sheet to be inspected 9a Pinhole image 9b Pinhole 10 CCD
10a CCD 1 cell 11 viewing angle adjustment film 12 louver in viewing angle adjustment film

Claims (7)

A CCD camera in which the area size of one pixel on the image scale is larger than the area size of the pinhole to be detected, a lens attached to the CCD camera, and a predetermined amount of light arranged on the opposite side of the CCD camera with respect to the inspection sheet. An optical pinhole inspection device composed of transmitted illumination. The optical pinhole inspection apparatus according to claim 1, wherein a dark box for preventing disturbance light from being applied to the imaging surface side of the inspection sheet is provided. The optical pinhole inspection apparatus according to claim 1 or 2, wherein the lens is provided with a diaphragm adjusting function. The optical pinhole inspection apparatus according to any one of claims 1 to 3, wherein uniform parallel light is used for transmitted illumination. The optical pinhole inspection device according to claim 4, wherein the uniform parallel light of the transmitted illumination is formed by installing the diffused light surface illumination at a position separated from the inspection sheet by a certain distance or more. The optical pinhole inspection according to claim 4, wherein the uniform parallel light of the transmitted illumination is formed by inserting between the inspection target sheet and the transmitted illumination of the diffused light in a state where two viewing angle adjusting films are overlapped. apparatus. A pinhole emits a predetermined amount of light from transillumination arranged on the opposite side of the CCD camera to the inspection sheet, and receives light passing through the pinhole with one pixel larger than the area size of the pinhole to be detected on the image scale. Optical pinhole inspection method to detect.

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