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CN-121994709-A - Imaging device and using method thereof

CN121994709ACN 121994709 ACN121994709 ACN 121994709ACN-121994709-A

Abstract

The invention discloses an imaging device and a using method of the imaging device, which are suitable for detecting defects on a flexible circuit board and comprise a camera, a high-angle light source, a light splitting sheet and a bowl-shaped light source. Through the combination of the multidirectional light sources and the use of the high-angle light sources, the product surface generates different degrees of light reflection, the three-dimensional information of the defects of the FPC product can be comprehensively obtained, the background information is restrained, and the excessive light reflection caused by flexible deformation and line edges is effectively eliminated.

Inventors

  • WANG LEI
  • TAN ENCHENG
  • LIN XIANJIN
  • LI SHANSHAN
  • XIANG JIE
  • CHEN XIAOBING

Assignees

  • 厦门威芯泰科技有限公司

Dates

Publication Date
20260508
Application Date
20260326

Claims (7)

  1. 1. An imaging device adapted to detect a defect (2) on a flexible circuit board, characterized by comprising A camera (7) adapted to receive signals reflected via the surface of the flexible circuit board in a first direction; a high angle light source comprising a number of concentrically arranged ring-shaped light sources (3), a ring-shaped top light source (12), said top light source (12) being adapted to emit light in a direction perpendicular to the first direction, A light splitting sheet (5) located in a first direction of a camera (7) and closer to the flexible circuit board than the camera (7), adapted to be transparent to signals reflected by the surface of the flexible circuit board, and adapted to reflect light from the top light source (12) to the surface of the flexible circuit board; The bowl-shaped light source is opened above and below, the inner diameter is gradually increased along the first direction and away from the direction of the camera (7), a plurality of groups of multidirectional light sources (4) distributed along the first direction are arranged on the bowl-shaped light source, and the multidirectional light sources (4) are annularly arranged and are suitable for emitting light to the surface of the flexible circuit board.
  2. 2. An imaging device according to claim 1, wherein the multi-directional light source (4) and the top light source (12) each comprise sets of fan-shaped light sources adapted to independently emit light onto the surface of the flexible circuit board.
  3. 3. An imaging device as claimed in claim 1, characterized in that the camera (7) has a telecentric lens (6), and in that the telecentric lens (6) has a continuously variable aperture stop.
  4. 4. An imaging device according to claim 1, further comprising an annular light source (3) positioned in a first direction of the bowl-shaped light source, arranged in an annular shape, and adapted to emit light onto the surface of the flexible circuit board.
  5. 5. A method of using an image forming apparatus according to any one of claims 1 to 4, comprising the steps of: Turning on and/or off the multi-directional light source (4) and the top light source (12) according to a lighting strategy for gradually increasing or decreasing the reflection of the surface of the flexible circuit board, and enabling the camera (7) to acquire the surface image of the flexible circuit board, and calculating the light intensity of the characteristic points according to the image until the light intensity of the characteristic points between two adjacent images meets the following formula: Wherein, I 1 and I 2 are the light intensity of the characteristic points of the two images respectively, M is a fixed threshold value, and the lighting mode corresponding to I 1 is used as the lighting mode adopted when detecting the defect (2).
  6. 6. A method of using an imaging device as defined in claim 5, wherein: Under the lambertian diffuse reflection model, the light intensity I of the surface characteristic points meets the following conditions: ; The method comprises the following steps of (I) carrying out light intensity on surface characteristic points in an imaging system; the diffuse reflection reflectivity of the surface at the point is used for representing the reflection capability of the material on incident light; A unit vector of the incident light direction for representing the illumination direction; n is a normal vector unit vector at the surface characteristic point and is used for representing the local geometric orientation of the point; ( ) The dot product of vectors L and N is equivalent to cos θ, where θ is the angle of the incident light direction from the surface normal.
  7. 7. A method of using an imaging apparatus as claimed in claim 5, characterized in that the camera (7) has a telecentric lens (6) and the telecentric lens (6) has a continuously variable aperture stop, the above steps are initially performed with the aperture stop having the smallest aperture, and after the lighting pattern used for detecting the defect (2) is obtained, the telecentric lens (6) is adjusted stepwise so as to receive the change of brightness just matching the photoimaging defect (2).

Description

Imaging device and using method thereof Technical Field The invention relates to the field of defect detection, in particular to an imaging device and a using method of the imaging device. Background For a flexible circuit board, under the influence of excessive light reflection caused by deformation, excessive light reflection caused by line edges and complex background, the mainstream 3D measurement method is intrinsically dependent on good diffuse reflection characteristics, when the flexible circuit board is applied to a high-reflection surface such as an FPC, data acquisition is easy to fail, the robustness cannot meet the industrial production requirement, the traditional fixed or simple partition illumination cannot cope with local high-intensity directional specular reflection caused by the deformation of the FPC, the incident angle of light cannot be actively and accurately controlled to avoid the field of view of a camera, and the defect detection difficulty of the FPC is high. Disclosure of Invention The present invention is directed to overcoming, or providing a material basis for overcoming, the above-mentioned drawbacks or problems occurring in the prior art, and to an imaging apparatus and a method of using the imaging apparatus. To achieve the above object, the present invention and its preferred embodiments adopt the following technical solutions but the embodiments are not limited to the following solutions: An imaging device for detecting defects on a flexible printed circuit board comprises A camera adapted to receive signals reflected via the surface of the flexible circuit board in a first direction; A high angle light source comprising a plurality of concentrically arranged ring-shaped top light sources adapted to emit light in a direction perpendicular to the first direction, A light splitting sheet, which is positioned in a first direction of the camera and is closer to the flexible circuit board than the camera, is suitable for transmitting signals reflected by the surface of the flexible circuit board, and is suitable for reflecting the light of the top light source to the surface of the flexible circuit board; The bowl-shaped light source is opened above and below, the inner diameter is gradually increased along the first direction and away from the direction of the camera, a plurality of groups of multidirectional light sources distributed along the first direction are arranged on the bowl-shaped light source, and the multidirectional light sources are annularly arranged and are suitable for emitting light to the surface of the flexible circuit board. In a second aspect, based on the first aspect, the multi-directional light source and the top light source each include a plurality of groups of sector light sources, and the sector light sources are adapted to independently emit light to the surface of the flexible circuit board. In a third aspect, based on the first aspect, the camera has a telecentric lens, and the telecentric lens has a plurality of diaphragms, and the aperture sizes of the diaphragms are different. According to a fourth aspect, based on the first aspect, the light source further comprises an annular light source, wherein the annular light source is located in the first direction of the bowl-shaped light source, is annularly arranged, and is suitable for emitting light to the surface of the flexible circuit board. A fifth aspect is a method of using an imaging apparatus, based on any one of the first to fourth aspects, comprising the steps of: According to the lighting strategy that the reflection of the surface of the flexible circuit board is gradually increased or reduced, a multidirectional light source and a top light source are turned on and/or off, and the camera acquires the surface image of the flexible circuit board: ; Wherein, I 1 and I 2 are the light intensity of the characteristic points of the two images respectively, M is a fixed threshold value, and the lighting mode corresponding to I 1 is used as the lighting mode adopted when detecting defects. In the sixth aspect, based on the fifth aspect, Under the lambertian diffuse reflection model, the light intensity I of the surface characteristic points meets the following conditions: ; The method comprises the following steps of (I) carrying out light intensity on surface characteristic points in an imaging system; the diffuse reflection reflectivity of the surface at the point is used for representing the reflection capability of the material on incident light; A unit vector of the incident light direction for representing the illumination direction; n is a normal vector unit vector at the surface characteristic point and is used for representing the local geometric orientation of the point; ( ) The dot product of vectors L and N is equivalent to cos θ, where θ is the angle of the incident light direction from the surface normal. Based on the scheme five, the camera is provided with a telecentric