Wafer OCR character code reader integrated with illumination function
By optimizing the optical design of the wafer OCR character reader and adopting a semi-reflective, semi-mirror lens and an independent light source, the problems of bulky size and uneven imaging in existing technologies are solved, achieving efficient and clear wafer engraved character recognition, adapting to complex environments, and simplifying equipment integration and maintenance.
Patent Information
- Application Number
- CN202422873497.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-09-19
- Estimated Expiration
- 2034-11-25
AI Technical Summary
Existing wafer OCR character readers are bulky due to the offset layout of the lighting source, which increases the installation space requirements. In addition, the oblique incidence of light causes uneven brightness and imaging interference in the engraved character area, making it difficult to integrate with other equipment and resulting in poor imaging quality.
An objective lens group, an imaging lens group, a half-reflecting half-mirror, a full reflector and a photosensitive receiver are used. The light source is directly opposite to the character engraving area of the wafer. The light illuminates the character area through the half-reflecting half-mirror and the objective lens group. The reflected light is projected onto the photosensitive receiver through the full reflector and the imaging lens group. The light source is preferably an independent light source or a combination of multiple light sources. The half-reflecting half-mirror is coated to control the visible light transmittance. The lens parameters are optimized to ensure uniform lighting and imaging quality.
It achieves uniform illumination of the wafer character marking area, reduces external light interference, improves imaging clarity and accuracy, has a compact structure for easy integration, adapts to complex environmental conditions, reduces chromatic aberration and distortion, and simplifies assembly and maintenance.
Smart Images
Figure CN223362658U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical sensor manufacturing, in particular to a wafer OCR character reader with integrated lighting function. Background Art
[0002] During the wafer production stage, a wafer OCR character reader is needed to read the OCR characters on the wafer to know the character number on each wafer for subsequent traceability.
[0003] The wafer OCR character reader is mainly composed of a shell, an optical lens group and an illumination light source. The optical lens group and the illumination light source are both hidden in the shell cavity, wherein the optical lens group is used to realize optical scanning and reflection detection of the characters, and the illumination light source is used to illuminate the wafer engraved character area to highlight the wafer character identification. In the prior art, the illumination light source is arranged in a biased state on one side of the objective lens group, and the emitted light is in an inclined state to directly illuminate the wafer engraved character area. In this way, on the one hand, subject to the biased layout of the illumination light source, the design of the wafer OCR character reader is large, which is bound to increase its demand for installation space, which is not conducive to its subsequent integration with equipment such as wafer sorting machines; on the other hand, due to the oblique incidence of light, the brightness distribution of the wafer engraved character area is uneven, and the surface reflection will aggravate the interference with the imaging, which is not conducive to enhancing the prominent wafer engraved character features. Therefore, it is urgent for those skilled in the art to solve the above problems. Utility Model Content
[0004] Therefore, in view of the above-mentioned existing problems and defects, the research and development team of this utility model project collected relevant information, conducted multiple evaluations and considerations, and after continuous experiments and modifications by the project research and development team members, finally led to the emergence of the wafer OCR character reader with integrated lighting function.
[0005] In order to solve the above-mentioned technical problems, the utility model relates to a wafer OCR character reader with integrated lighting function, which is used to extract characters engraved on a wafer into machine-readable text, and includes an objective lens group, an imaging lens group, a half-reflecting half-mirror, a total reflection mirror, a photosensitive receiver, and a light source. The objective lens group, the half-reflecting half-mirror, the total reflection mirror, and the imaging lens group are arranged in sequence from the object side to the image side to jointly constitute an imaging light path. The half-reflecting half-mirror is crossed by the optical axis of the objective lens group. The light source is directly opposite to the wafer engraved character area, and the light emitted by it passes through the half-reflecting half-mirror and the objective lens group in sequence to illuminate the wafer engraved character area, and the light reflected from the wafer engraved character area passes through the half-reflecting half-mirror, the total reflection mirror, and the imaging lens group in sequence to project to the photosensitive receiver.
[0006] As a further improvement of the technical solution disclosed in the present invention, the light source is preferably an independent light emitting body, and the light axis of the objective lens group passes through it.
[0007] Of course, as another modified design of the above technical solution, the light source is composed of a plurality of independent light-emitting bodies. The common line connecting the plurality of independent light-emitting bodies is perpendicular to the optical axis of the objective lens group, and the upper limit of the distance between the common line connecting the plurality of independent light-emitting bodies and the optical axis of the objective lens group is set to a.
[0008] As a further improvement of the technical solution disclosed in the present invention, the semi-reflective and semi-mirror lens is coated, and its visible light transmittance is controlled at 50-55% within the visible light band of 380-780nm.
[0009] As a further improvement of the technical solution disclosed in the present utility model, F represents the effective focal length of the imaging optical path, FOV represents the total field of view angle of the imaging optical path, and TTL represents the total length of the imaging optical path. Then, 6<F<6.5, 42°<FOV<45°, and 8<TTL<8.5.
[0010] As a further improvement to the technical solution disclosed in this utility model, the objective lens group is composed of a front lens and a rear lens arranged in order from the object side to the image side. The front lens has negative optical power, its object side is flat, and its image side is convex. The rear lens has positive optical power, its object side is convex, and its image side is flat.
[0011] As a further improvement of the technical solution disclosed in the present utility model, the front lens satisfies the following conditions: 1.9<Nd1<2.3, 18<Vd1<20, wherein Nd1 represents the light refractive index of the front lens, and Vd1 represents the Abbe constant of the front lens; the rear lens satisfies the following conditions: 1.2<Nd2<1.28, 75<Vd2<83, wherein Nd2 represents the light refractive index of the rear lens, and Vd2 represents the Abbe constant of the rear lens.
[0012] In practical applications, the wafer OCR character reader with integrated lighting function disclosed in the present invention can achieve at least the following beneficial technical effects, specifically:
[0013] 1) Thanks to the optical properties of the semi-reflective, semi-mirror lens, the light source can achieve axial illumination of the wafer marking area. Compared with traditional light source offset solutions, this provides more uniform illumination and can overcome imaging interference caused by surface reflections. It creates a sharp contrast between the diffuse and absorptive surfaces, which helps to enhance the wafer marking characteristics.
[0014] 2) The components of the wafer OCR character reader are integrated into a single module, eliminating non-axial optical propagation and significantly reducing interference from external ambient light. This ensures that the wafer OCR character reader has good imaging capabilities even in low light intensity or complex environmental conditions.
[0015] 3) During the image acquisition process, the half-reflecting half-mirror partially splits the light emitted by the light source, and the light path returned by the split light serves as the feedback signal of the photosensitive receiver. The photosensitive receiver converts the intensity of the reflected light into an electrical signal to form an image, which can reduce the incidence of imaging defects such as chromatic aberration and distortion to a certain extent, and help ensure the accuracy and clarity of the imaging;
[0016] 4) The total number of optical components included is relatively small and integrated into an independent module. The design structure is relatively simple and compact, and is conducive to assembly and maintenance operations. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0018] Figure 1 This is a structural diagram of the wafer OCR character reader with integrated lighting function disclosed in the utility model.
[0019] Figure 2 This is a schematic diagram of the imaging rules of the wafer OCR character reader with integrated lighting function disclosed in the present utility model (with the light source hidden).
[0020] Figure 3 This is a schematic diagram of the imaging rules of the wafer OCR character reader with integrated lighting function disclosed in the present invention (in the state of a single independent light source).
[0021] Figure 4 This is a schematic diagram of the imaging rules of the wafer OCR character reader with integrated lighting function disclosed in the present invention (when multiple independent light sources are used in combination).
[0022] 1-Objective lens group; 11-Front lens; 12-Rear lens; 2-Imaging mirror group; 3-Half-reflective half-mirror; 4-Total reflection mirror; 5-Photosensitive receiver; 6-Light source; 61-Independent light source. DETAILED DESCRIPTION
[0023] As wafer manufacturing technology rapidly advances, optical character recognition (OCR) technology, a key technology, is becoming an important means of improving production efficiency and ensuring product quality. Wafer OCR barcode readers use industrial cameras to capture images and, through image processing and character recognition algorithms, convert the character information in the image into editable text.
[0024] The following is a detailed description of the present invention in conjunction with specific embodiments. Figure 1 The schematic diagram of the structure of the wafer OCR character reader with integrated lighting function disclosed in the present invention is shown. It can be seen that it mainly consists of a housing (not shown in the figure), an objective lens group 1, an imaging lens group 2, a half-reflecting mirror 3, a total reflection mirror 4, a photosensitive receiver 5 and a light source 6. Among them, the objective lens group 1, the half-reflecting mirror 3, the total reflection mirror 4 and the imaging lens group 2 are arranged in sequence from the object side to the image side to form an imaging light path (such as Figure 2 ). The objective lens group 1 is composed of a front lens 11 and a rear lens 12 arranged in sequence from the object side to the image side. The front lens 11 has a negative optical focal length, and its object side is a plane, and its image side is a convex surface. The rear lens 12 has a positive optical focal length, and its object side is a convex surface, and its image side is a plane. The half-reflecting half-mirror 3 is coated, and its visible light transmittance is controlled at 50-55% in the visible light band of 380-780nm. The half-reflecting half-mirror 3 is crossed by the optical axis of the objective lens group 1. The light source 6 is an independent light-emitting body 61, which is located directly behind the half-reflecting half-mirror 3 and is crossed by the optical axis of the objective lens group 1. The light emitted by the light source 6 passes through the half-reflecting half-mirror 3 and the objective lens group 1 in sequence to illuminate the wafer engraving character area, and the light reflected from the wafer engraving character area passes through the half-reflecting half-mirror 3, the total reflection mirror 4, and the imaging lens group 2 in sequence to project to the photosensitive receiver 5 (as shown in FIG. Figure 3 ). The photosensitive receiver 5 determines the shape of the wafer character by detecting the dark and light patterns to generate a black and white dot matrix image file, and then converts the text in the image into text format through recognition software.
[0025] In practical applications, the wafer OCR character reader with integrated lighting function disclosed in the present invention has achieved at least the following beneficial technical effects, specifically:
[0026] 1) Thanks to the optical properties of the half-reflecting half-mirror 3, the light source 6 is able to achieve axial illumination of the wafer marking area, providing more uniform illumination and overcoming imaging interference caused by surface reflections. This creates a sharp contrast between the diffuse and absorptive surfaces, which helps enhance the wafer marking characteristics.
[0027] 2) All components of the wafer OCR character reader are assembled in the housing cavity to form an independent module, thereby eliminating non-axial optical propagation and significantly reducing interference from external ambient light, ensuring that the wafer OCR character reader has good imaging capabilities under insufficient light intensity or complex environmental conditions;
[0028] 3) During the image acquisition process, the half-reflecting half-mirror 3 partially splits the light emitted by the light source 6, and the light path returned by the splitting serves as the feedback signal of the photosensitive receiver. The photosensitive receiver 5 converts the intensity of the reflected light into an electrical signal to form an image, which can reduce the incidence of imaging defects such as chromatic aberration and distortion to a certain extent, and is conducive to ensuring the accuracy and clarity of the imaging.
[0029] It should also be noted here that the wafer OCR character reader with integrated lighting function disclosed in this embodiment contains a relatively small number of optical elements, which are integrated into an independent module. The design structure is relatively simple and compact, and is conducive to assembly and maintenance operations.
[0030] Furthermore, to further enhance imaging quality and as a further optimization of the above technical solution, F represents the effective focal length of the imaging optical path, FOV represents the total field of view (FTO) of the imaging optical path, and TTL represents the total length of the imaging optical path. Therefore, 6 < F < 6.5, 42° < FOV < 45°, and 8 < TTL < 8.5. By controlling the wafer OCR character reader's effective focal length, total field of view (FOV), and optical path assembly parameters, the imaging process is minimized with relatively minimal optical distortion and image deformation, ensuring imaging quality and facilitating the subsequent recognition and determination of wafer OCR character imaging details.
[0031] According to actual experimental results, better imaging effect and imaging accuracy can be achieved when the parameters of the front lens 11 and the rear lens 12 meet the following conditions, specifically: 1.9<Nd1<2.3, 18<Vd1<20, where Nd1 represents the light refractive index of the front lens 11, and Vd1 represents the Abbe constant of the front lens 11; the rear lens meets the following conditions: 1.2<Nd2<1.28, 75<Vd2<83, where Nd2 represents the light refractive index of the rear lens 12, and Vd2 represents the Abbe constant of the rear lens 12.
[0032] The actual experimental results show that when the wafer to be identified is kept in an upright position, the wafer OCR character reader with integrated lighting function disclosed in the above embodiment can accurately and clearly pick up the OCR character image. However, when the wafer to be identified is in a non-upright tilted position, the imaging effect is poor, the imaging clarity is insufficient, and some OCR characters are sometimes missed. In view of this, Figure 4The following is a schematic diagram showing the imaging pattern of the wafer OCR character reader with integrated lighting function disclosed by the present invention when multiple independent light-emitting bodies are used together. It can be seen that the difference compared with the above-mentioned embodiment is that the light source 6 is composed of two independent light-emitting bodies 61. Among them, one independent light-emitting body 61 is crossed by the optical axis of the objective lens group 1, while the other independent light-emitting body 61 deviates from the optical axis of the objective lens group 1 by a certain distance, and the line connecting the two independent light-emitting bodies 61 is perpendicular to the optical axis of the objective lens group 1. When the wafer to be identified is kept in an upright tilted posture, the independent light-emitting body 61 crossed by the optical axis of the objective lens group 1 can effectively enhance the display of the wafer OCR characters; and when the wafer to be identified is kept in a non-upright tilted posture, the other independent light-emitting body 61 offset relative to the optical axis of the objective lens group 1 works to enhance the display of the wafer OCR characters.
[0033] Here, it should be noted that the number of independent light-emitting bodies 61 is not limited to 2, and the number can be increased according to specific application scenarios.
[0034] Of course, in actual R&D and design, a single-chip microcomputer can also be used to independently control the on / off status of each light emitting element 61. During the process of performing wafer OCR character image capture by the photosensitive receiver 5, under the control of the single-chip microcomputer, the independent light emitting elements 61 are sequentially turned on from the center to the sides, while the remaining independent light emitting elements 61 remain off. During this process, the computer image processing system sequentially determines the clarity of the wafer OCR character image until it meets the expected requirements, thus completing the OCR character imaging operation for a single wafer.
[0035] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A wafer OCR character reader with integrated lighting function, used to extract characters engraved on a wafer into machine-readable text, comprising an objective lens group, an imaging lens group, a half-reflecting mirror, a full-reflecting mirror, a photosensitive receiver, and a light source, characterized in that: The objective lens group, the half-reflecting half-mirror, the total reflection mirror, and the imaging lens group are arranged in sequence from the object side to the image side to jointly constitute an imaging light path; the half-reflecting half-mirror is crossed by the optical axis of the objective lens group; the light source is directly opposite to the wafer engraving character area, and the light emitted by it illuminates the wafer engraving character area through the half-reflecting half-mirror and the objective lens group in sequence, and the light reflected from the wafer engraving character area passes through the half-reflecting half-mirror, the total reflection mirror, and the imaging lens group in sequence to be projected onto the photosensitive receiver.
2. The wafer OCR character reader with integrated lighting function according to claim 1, characterized in that: The light source is an independent light emitting body and is passed through by the optical axis of the objective lens group.
3. The wafer OCR character reader with integrated lighting function according to claim 1, characterized in that: The light source is composed of a plurality of independent light-emitting bodies. A common line connecting the plurality of independent light-emitting bodies is perpendicular to the optical axis of the objective lens group, and an upper limit of a distance between the common line connecting the plurality of independent light-emitting bodies and the optical axis of the objective lens group is set.
4. The wafer OCR character reader with integrated lighting function according to claim 1, characterized in that: The semi-reflective and semi-mirror lens is provided with a coating, and within the visible light band of 380-780 nm, its visible light transmittance is controlled at 50-55%.
5. The wafer OCR character reader with integrated lighting function according to any one of claims 1 to 4, characterized in that: F represents the effective focal length of the imaging optical path, FOV represents the total field of view of the imaging optical path, and TTL represents the total length of the imaging optical path. Then, 6<F<6.5, 42°<FOV<45°, and 8<TTL<8.
5.
6. The wafer OCR character reader with integrated lighting function according to claim 5, characterized in that: The objective lens group is composed of a front lens and a rear lens arranged in sequence from the object side to the image side; the front lens has a negative optical focal length, its object side is a flat surface, and its image side is a convex surface; the rear lens has a positive optical focal length, its object side is a convex surface, and its image side is a flat surface.
7. The wafer OCR character reader with integrated lighting function according to claim 6, characterized in that: The front lens satisfies the following conditions: 1.9<Nd1<2.3, 18<Vd1<20, wherein Nd1 represents the light refractive index of the front lens, and Vd1 represents the Abbe constant of the front lens; the rear lens satisfies the following conditions: 1.2<Nd2<1.28, 75<Vd2<83, wherein Nd2 represents the light refractive index of the rear lens, and Vd2 represents the Abbe constant of the rear lens.