Wafer OCR character code reader integrated with illumination function

Abstract

The invention relates to the technical field of optical sensor manufacturing, in particular to a wafer OCR character code reader integrated with an illumination function. And the objective lens group, the semi-reflecting and semi-transmitting mirror, the total reflection mirror and the imaging lens group are sequentially arranged along the direction from the object space to the image space. The semi-reflecting and semi-transmitting mirror is traversed by the optical axis of the objective lens group. The light source is right opposite to the wafer marking character area, emitted light sequentially passes through the semi-reflecting and semi-transmitting mirror and the objective lens group to illuminate the wafer marking character area, and light reflected by the wafer marking character area sequentially passes through the semi-reflecting and semi-transmitting mirror, the total reflection mirror and the imaging lens group to be projected to the photosensitive receiver. Thus, on one hand, axial irradiation of a wafer engraved character area is realized, more uniform illumination is provided for the wafer engraved character area, imaging interference caused by surface reflection can be overcome, and wafer engraved character features can be enhanced; on the other hand, all the components are integrated into an independent module, the design structure is compact, and interference from the external environment can be greatly weakened.

Description

Technical Field

[0001] The invention 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 it in order 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 on one side of the objective lens group in a biased state, and the emitted light directly illuminates the wafer engraved character area in an inclined state. 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 handling 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. Summary of the invention

[0004] Therefore, in view of the above existing problems and defects, the project development team of the present invention collected relevant information, conducted multiple evaluations and considerations, and after continuous experiments and modifications by the project development team, the wafer OCR character reader with integrated lighting function finally appeared.

[0005] In order to solve the above technical problems, the present invention relates to a wafer OCR character reader with integrated lighting function, which is used to extract the characters engraved on the wafer into machine-readable text, including 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 form 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 illuminates the wafer engraved character area through the half-reflecting half-mirror and the objective lens group in sequence, and the light reflected from the wafer engraved character area is projected to the photosensitive receiver through the half-reflecting half-mirror, the total reflection mirror and the imaging lens group in sequence.

[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 emitters. The common line of the plurality of independent light emitters is perpendicular to the optical axis of the objective lens group, and the upper limit of the distance between the common line of the plurality of independent light emitters 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 provided with a coating, and within the visible light band of 380-780nm, its visible light transmittance is controlled at 50-55%.

[0009] As a further improvement of the technical solution disclosed in the present invention, 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.

[0010] As a further improvement of the technical solution disclosed in the present invention, 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, and its object side is a flat surface, and its image side is a convex surface. The rear lens has a positive optical focal length, and its object side is a convex surface, and its image side is a flat surface.

[0011] As a further improvement of the technical solution disclosed in the present invention, 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 half-reflective and half-mirror lens, the light source can achieve axial illumination of the wafer character marking area. Compared with the traditional light source bias solution, it provides more uniform illumination and can overcome the imaging interference caused by surface reflection, forming a sharp contrast between the diffuse surface and the absorption surface, which is conducive to enhancing the wafer character marking characteristics;

[0014] 2) The components of the wafer OCR character reader are integrated into an independent module, which can eliminate the propagation of non-axial optics, greatly reduce the interference from external ambient light, and ensure that the wafer OCR character reader has good imaging capabilities under insufficient 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 splitting is used 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 is conducive to ensuring 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 it is convenient to perform assembly and maintenance operations on it. 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0018] Figure 1 It is a structural schematic diagram of the wafer OCR character reader with integrated lighting function disclosed in the present invention.

[0019] Figure 2 It is a schematic diagram of the imaging law of the wafer OCR character reader with integrated lighting function disclosed in the present invention (when the light source is hidden).

[0020] Figure 3 It is a schematic diagram of the imaging law 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 It 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 and half-mirror; 4-total reflector; 5-photosensitive receiver; 6-light source; 61-independent light source. DETAILED DESCRIPTION

[0023] As wafer manufacturing technology develops rapidly, OCR character technology, as a key technology, is gradually becoming an important means to improve production efficiency and ensure product quality. Wafer OCR character readers use industrial cameras to capture images and convert character information in images into editable text through image processing and character recognition algorithms.

[0024] The following is a further detailed description of the present invention in conjunction with specific embodiments. Figure 1The schematic diagram of the structure of the wafer OCR character code reader with integrated lighting function disclosed in the present invention is shown. It can be seen that it is mainly composed of a housing (not shown in the figure), an objective lens group 1, an imaging lens group 2, a half-reflecting half-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 half-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 jointly form an imaging optical 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 semi-reflective half-mirror 3 has a coating, and its visible light transmittance is controlled to be 50-55% in the visible light band of 380-780nm. The semi-reflective half-mirror 3 is crossed by the optical axis of the objective lens group 1. The light source 6 is an independent light source 61, which is located directly behind the semi-reflective half-mirror 3, and is crossed by the optical axis of the objective lens group 1. The light emitted by the light source 6 illuminates the wafer engraving character area in sequence through the semi-reflective half-mirror 3 and the objective lens group 1, and the light reflected from the wafer engraving character area is projected to the photosensitive receiver 5 (as shown in FIG. 1 ). 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 a 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 semi-reflective and semi-transparent mirror 3, the light source 6 can achieve axial illumination of the wafer engraving character area, providing it with more uniform illumination, and can overcome the imaging interference caused by surface reflection, forming a sharp contrast between the diffuse surface and the absorption surface, which is conducive to strengthening the wafer engraving character characteristics;

[0027] 2) All components of the wafer OCR character reader are assembled in the shell cavity to form an independent module, thereby eliminating the propagation of non-axial optics, which is conducive to greatly reducing the interference from external ambient light and 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 semi-reflective mirror 3 partially splits the light emitted by the light source 6, and the split light path 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] Here, it is also necessary to explain that the total number of optical elements included in the wafer OCR character reader with integrated lighting function disclosed in this embodiment is relatively small, and is integrated into an independent module. The design structure is relatively simple and compact, and is conducive to assembly and maintenance operations.

[0030] Furthermore, in order to further improve the imaging quality, 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 of the imaging optical path, and TTL represents the total length of the imaging optical path, then, 6<F<6.5, 42°<FOV<45°, 8<TTL<8.5. In this way, by controlling the effective focal length, total field of view, and optical path assembly parameters of the wafer OCR character reader, it has relatively small optical distortion and image deformation during the imaging process, ensuring the imaging quality, which is conducive to the subsequent recognition and judgment of the 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, which are as follows: 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 not good, the imaging clarity is insufficient, and some OCR characters are sometimes missed. In view of this, Figure 4The schematic diagram of the imaging rule of the wafer OCR character reader with integrated lighting function disclosed in the present invention under the state of using multiple independent light-emitting bodies simultaneously is shown. 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, and the other independent light-emitting body 61 deviates from the optical axis of the objective lens group 1 by a certain distance, and the connecting line of 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 takes effect 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 research and development design, the single chip microcomputer can also be used to realize independent control of the on / off state of each light emitting body 61. In the process of the photosensitive receiver 5 performing wafer OCR character image pickup, under the control of the single chip microcomputer, the independent light emitting bodies 61 are turned on in sequence from the center to the sides, while the other independent light emitting bodies 61 remain in the off state. In this process, the computer image processing system sequentially determines the clarity of the wafer OCR character imaging until it meets the expected requirements. At this point, the OCR character imaging operation of a single wafer is completed.

[0035] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those 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 will not be limited to the embodiments shown herein, but rather 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 half-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 form 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 is projected to the photosensitive receiver through the half-reflecting half-mirror, the total reflection mirror, and the imaging lens group in sequence.

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 traversed 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 to a.

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 380-780nm, 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.

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