Backlight for optical detection and method of controlling the same

Abstract

The present disclosure provides a backlight source for optical detection and a control method thereof. The backlight source comprises a carrier, a backlight plate, a plurality of lamp beads, a first control circuit and a second control circuit. The backlight plate is located on the carrier and has a groove. The plurality of lamp beads comprises a plurality of first lamp beads arranged at the bottom of the groove and a plurality of second lamp beads. The plurality of first lamp beads are arranged in multiple circles in the middle of the groove, and the plurality of second lamp beads are arranged in multiple circles at the edge of the groove. The distance D1 between an adjacent circle of the first lamp beads and an adjacent circle of the second lamp beads is greater than the distance D2 between two adjacent circles of the first lamp beads, and the distance D1 between an adjacent circle of the first lamp beads and an adjacent circle of the second lamp beads is greater than the distance D3 between two adjacent circles of the second lamp beads. The first control circuit is electrically connected to the plurality of first lamp beads respectively, and is used for controlling the brightness of the plurality of first lamp beads. The second control circuit is electrically connected to the plurality of second lamp beads respectively, and is used for controlling the brightness of the plurality of second lamp beads.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to a backlight source for optical detection and a control method thereof. Background Technology

[0002] In the semiconductor manufacturing process, Automatic Optical Inspection (AOI) is a technology that automatically identifies grain defects in wafers through optical imaging and algorithm analysis.

[0003] Backlighting is a key component of AOI (Optical Inspection) technology. A typical backlighting system for optical inspection includes a stage, a backlight panel, multiple LEDs, and control circuitry. The backlight panel is located on the stage and has recesses. Multiple LEDs are arranged in multiple rings at the bottom of these recesses. The control circuitry is electrically connected to the LEDs and controls their brightness.

[0004] However, current backlights have gaps between the center and the edges due to gaps between the outer ring LEDs and the edge of the platform. Summary of the Invention

[0005] This disclosure provides a backlight source for optical detection and a control method thereof to reduce the brightness difference between the center and the edge. The technical solution is as follows: In a first aspect, embodiments of this disclosure provide a backlight source for optical detection, the backlight source comprising: a stage, a backlight plate, multiple LEDs, a first control circuit, and a second control circuit; The backlight panel is located on the platform, and the backlight panel has a groove; The plurality of LED beads includes a plurality of first LED beads and a plurality of second LED beads arranged at the bottom of the groove. The plurality of first LED beads are arranged in multiple rings in the middle of the groove, and the plurality of second LED beads are arranged in multiple rings at the edge of the groove. The distance D1 between an adjacent ring of first LED beads and a ring of second LED beads is greater than the distance D2 between two adjacent rings of first LED beads, and the distance D1 between an adjacent ring of first LED beads and a ring of second LED beads is greater than the distance D3 between two adjacent rings of second LED beads. The first control circuit is electrically connected to each of the plurality of first LED beads and is used to control the brightness of the plurality of first LED beads; The second control circuit is electrically connected to each of the plurality of second LED beads and is used to control the brightness of the plurality of second LED beads.

[0006] Optionally, the spacing D1 between adjacent rings of the first LED beads and rings of the second LED beads is 6.5~7.5mm; The spacing D2 between two adjacent rings of the first LED beads is 5.5~6.5mm; The spacing D3 between two adjacent rings of the second LED is 5.5~6.5mm.

[0007] Optionally, the backlight source further includes: a reflective layer; The reflective layer is attached to the sidewall of the groove.

[0008] Optionally, the reflective layer is a reflective BOPP layer.

[0009] Optionally, the thickness of the reflective layer is 0.05~0.07mm.

[0010] Optionally, the backlight further includes: a first brightness sensor and a second brightness sensor; The first brightness sensor is used to detect the first brightness at the plurality of first LED beads; The second brightness sensor is used to detect the second brightness at the plurality of second LED beads; The first control circuit is used to determine the brightness of each of the first LED beads based on the total brightness; determine the base current of the first LED beads based on the brightness of the first LED beads and the brightness-current curve; determine the first current compensation value based on the difference between the first brightness and the first target brightness in the previous cycle; determine the driving current of the first LED beads based on the base current of the first LED beads and the first current compensation value; and control the multiple first LED beads to emit light using the driving current of the first LED beads. The second control circuit is used to determine the brightness of each second LED bead based on the total brightness; determine the base current of the second LED bead based on the brightness of the second LED bead and the brightness-current curve; determine the second current compensation value based on the difference between the second brightness and the second target brightness in the previous cycle; determine the driving current of the second LED bead based on the base current of the second LED bead and the second current compensation value; and control the multiple second LED beads to emit light using the driving current of the second LED beads.

[0011] Optionally, the first control circuit is configured to determine the brightness ratio of the plurality of first LED beads and the plurality of second LED beads based on the size of the chip to be tested; determine the brightness of the plurality of first LED beads based on the brightness ratio and the total brightness; and determine the brightness of each first LED bead based on the brightness of the plurality of first LED beads. The second control circuit is used to determine the brightness ratio of the plurality of first LED beads and the plurality of second LED beads based on the size of the chip to be tested; to determine the brightness of the plurality of second LED beads based on the brightness ratio and the total brightness; and to determine the brightness of each second LED bead based on the brightness of the plurality of second LED beads.

[0012] Optionally, when the size of the chip to be tested only covers the plurality of first LED beads, the brightness of the plurality of first LED beads is much greater than the brightness of the plurality of second LED beads; When the size of the chip to be tested covers the plurality of first LED beads and part of the second LED beads, the brightness of the plurality of first LED beads is greater than the brightness of the plurality of second LED beads; When the size of the chip to be tested completely covers the plurality of first LED beads and the plurality of second LED beads, the brightness of the plurality of first LED beads is not greater than the brightness of the plurality of second LED beads.

[0013] In a second aspect, embodiments of this disclosure provide a control method for a backlight source as described in any one of the first aspects, the method comprising: Detect the first brightness at the plurality of first LED beads; detect the second brightness at the plurality of second LED beads; The brightness of each of the first LED beads is determined based on the total brightness; the brightness of each of the second LED beads is determined based on the total brightness; Based on the brightness of the first LED and its brightness-current curve, determine the base current of the first LED; based on the brightness of the second LED and its brightness-current curve, determine the base current of the second LED. Based on the difference between the first brightness and the first target brightness in the previous cycle, a first current compensation value is determined; based on the difference between the second brightness and the second target brightness in the previous cycle, a second current compensation value is determined. The driving current of the first LED is determined based on the base current of the first LED and the first current compensation value; the driving current of the second LED is determined based on the base current of the second LED and the second current compensation value. The driving current of the first LED bead is used to control the light emission of the plurality of first LED beads; the driving current of the second LED bead is used to control the light emission of the plurality of second LED beads.

[0014] Optionally, the brightness of each of the first LED beads is determined based on the total brightness; determining the brightness of each of the second LED beads based on the total brightness includes: Based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads and the plurality of second LED beads is determined; based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads and the plurality of second LED beads is determined. The brightness of the plurality of first LED beads is determined based on the brightness ratio and the total brightness; the brightness of the plurality of second LED beads is determined based on the brightness ratio and the total brightness. The brightness of each first LED is determined based on the brightness of the plurality of first LEDs; the brightness of each second LED is determined based on the brightness of the plurality of second LEDs.

[0015] The beneficial effects of the technical solutions provided in this disclosure are: In this embodiment, the LEDs are distributed in two regions: an inner ring (first LED) and an outer ring (second LED). A larger isolation gap is reserved between the inner and outer rings, significantly reducing the area of ​​light overlap and naturally reducing brightness superposition interference. Simultaneously, the inner and outer rings are controlled by separate control circuits. Due to the reduced superposition interference, only simple weight compensation is needed to offset the brightness difference in the transition area between the inner and outer rings, resulting in stronger optical uniformity and stability.

[0016] Furthermore, the independent control of the inner and outer rings of the backlight technology allows for flexible adaptation to different chip sizes and testing requirements, resulting in better brightness uniformity and adjustability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a backlight for optical detection provided in an embodiment of this disclosure; Figure 2 This is a circuit diagram of a backlight for optical detection provided in an embodiment of this disclosure; Figure 3 This is a flowchart of a backlight control method provided in an embodiment of the present disclosure.

[0019] Explanation of reference numerals in the attached figures: 100: Stage; 200: Backlight panel; 300: LED bead; 201: Groove; 301: First LED bead; 302: Second LED bead; 400: First control circuit; 500: Second control circuit; 600: Reflective layer; 700: First brightness sensor; 800: Second brightness sensor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of a backlight source for optical detection provided in an embodiment of this disclosure. Figure 1 As shown, the backlight source includes: a stage 100, a backlight panel 200, and multiple LED beads 300.

[0022] The backlight panel 200 is located on the stage 100, and the backlight panel 200 has a groove 201.

[0023] The plurality of LED beads 300 includes a plurality of first LED beads 301 and a plurality of second LED beads 302 arranged at the bottom of the groove 201. The plurality of first LED beads 301 are arranged in multiple rings in the middle of the groove 201, and the plurality of second LED beads 302 are arranged in multiple rings at the edge of the groove 201. The distance D1 between an adjacent ring of first LED beads 301 and a ring of second LED beads 302 is greater than the distance D2 between two adjacent rings of first LED beads 301, and the distance D1 between an adjacent ring of first LED beads 301 and a ring of second LED beads 302 is greater than the distance D3 between two adjacent rings of second LED beads 302.

[0024] In this embodiment of the disclosure, the stage 100 is rectangular, and the backlight plate 200 and the groove 201 are circular.

[0025] In other embodiments, the stage 100, the backlight plate 200, and the groove 201 may also be of other shapes.

[0026] In this embodiment of the disclosure, the backlight panel 200 refers to the support plate of the backlight source, which is used to arrange multiple LED beads.

[0027] Figure 2 This is a circuit diagram of a backlight for optical detection provided in an embodiment of this disclosure. Figure 2 As shown, there is a first control circuit 400 and a second control circuit 500.

[0028] The first control circuit 400 is electrically connected to the plurality of first lamp beads 301 respectively, and is used to control the brightness of the plurality of first lamp beads 301.

[0029] The second control circuit 500 is electrically connected to the plurality of second LED beads 302 respectively, and is used to control the brightness of the plurality of second LED beads 302.

[0030] In this embodiment, the LEDs are distributed in two regions: an inner ring (first LED) and an outer ring (second LED). A larger isolation gap is reserved between the inner and outer rings, significantly reducing the area of ​​light overlap and naturally reducing brightness superposition interference. Simultaneously, the inner and outer rings are controlled by separate control circuits. Due to the reduced superposition interference, only simple weight compensation is needed to offset the brightness difference in the transition area between the inner and outer rings, resulting in stronger optical uniformity and stability.

[0031] Furthermore, the independent control of the inner and outer rings of the backlight technology allows for flexible adaptation to different chip sizes and testing requirements, resulting in better brightness uniformity and adjustability.

[0032] In this embodiment, each ring is arranged in a circular pattern. This circular arrangement ensures high uniformity, avoids vignetting at the edges, and guarantees consistent imaging across the entire chip area.

[0033] In other embodiments, each ring arrangement may also be of other shapes.

[0034] In this embodiment of the disclosure, the multiple rings of first LED beads 301 in the inner ring are arranged at equal intervals, and the first LED beads 301 in each ring of first LED beads 301 are also arranged at equal intervals.

[0035] The outer ring has multiple rings of second LED beads 302 arranged at equal intervals, and the second LED beads 302 in each ring are also arranged at equal intervals.

[0036] For example, the spacing between two adjacent rings of first LED beads 301 is the same as the spacing between two adjacent first LED beads 301 in the same ring. The spacing between two adjacent rings of second LED beads 302 is the same as the spacing between two adjacent second LED beads 302 in the same ring.

[0037] For example, the spacing between two adjacent rings of first LED beads 301 is the same as the spacing between two adjacent rings of second LED beads 302. The spacing between two adjacent first LED beads 301 in the same ring is the same as the spacing between two adjacent second LED beads 302 in the same ring.

[0038] In this embodiment of the present disclosure, the spacing D1 between an adjacent ring of the first LED beads 301 and a ring of the second LED beads 302 is 6.5~7.5mm.

[0039] The spacing D2 between two adjacent rings of the first LED beads 301 is 5.5~6.5mm; the spacing D3 between two adjacent rings of the second LED beads 302 is 5.5~6.5mm.

[0040] In this implementation, each ring of LED beads is evenly distributed along the circumference. The center-to-center distance between adjacent LED beads in the inner or outer ring is 5.5~6.5mm. As the diameter of the ring increases, the number of LED beads in a single ring of the outer ring increases synchronously to ensure consistent density per unit circumference and uniform brightness. The distance between the inner and outer rings of LED beads is 6.5~7.5mm, which is a reserved gap to avoid large-area overlap and interference of light from adjacent rings.

[0041] For example, the spacing D1 between adjacent rings of the first LED beads 301 and the second LED beads 302 is 7 mm.

[0042] The spacing D2 between two adjacent rings of the first LED beads 301 is 6mm; the spacing D3 between two adjacent rings of the second LED beads 302 is 6mm.

[0043] In other embodiments, the spacing between two adjacent rings of first LED beads 301 and the spacing between two adjacent rings of second LED beads 302 can be different. The spacing between two adjacent first LED beads 301 and two adjacent second LED beads 302 in the same ring can also be different.

[0044] For example, the spacing between two adjacent rings of first LED beads 301 is smaller than the spacing between two adjacent rings of second LED beads 302. The spacing between two adjacent first LED beads 301 within the same ring is smaller than the spacing between two adjacent second LED beads 302 within the same ring.

[0045] See you again Figure 1 The backlight also includes a reflective layer 600; the reflective layer 600 is attached to the sidewall of the groove 201.

[0046] In this implementation, the reflective layer 600 can reduce light leakage, improve contrast, and suppress background stray light.

[0047] In this embodiment of the disclosure, the reflective layer 600 can be a reflective tape layer.

[0048] For example, the reflective layer 600 is a reflective biaxially oriented polypropylene (BOPP) film layer, such as an aluminized BOPP layer or a pearlescent BOPP layer, to ensure reflective effect.

[0049] In this embodiment of the disclosure, the thickness of the reflective layer 600 is 0.05~0.07mm.

[0050] In this implementation, using a reflective layer 600 of the aforementioned thickness can ensure the reflective effect without taking up too much space.

[0051] For example, the thickness of the reflective layer 600 is 0.06 mm.

[0052] See you again Figure 2 The backlight also includes a first brightness sensor 700 and a second brightness sensor 800.

[0053] The first brightness sensor 700 is electrically connected to the first control circuit 400, and the second brightness sensor 800 is electrically connected to the second control circuit 500.

[0054] The first brightness sensor 700 is used to detect the first brightness at the plurality of first LED beads 301.

[0055] The second brightness sensor 800 is used to detect the second brightness at the plurality of second LED beads 302.

[0056] The first control circuit 400 is used to determine the brightness of each of the first LED beads 301 based on the total brightness; determine the base current of the first LED beads 301 based on the brightness of the first LED beads 301 and the brightness-current curve; determine a first current compensation value based on the difference between the first brightness and the first target brightness in the previous cycle; determine the driving current of the first LED beads 301 based on the base current of the first LED beads 301 and the first current compensation value; and control the plurality of first LED beads 301 to emit light using the driving current of the first LED beads 301.

[0057] The second control circuit 500 is used to determine the brightness of each of the second LED beads 302 based on the total brightness; determine the base current of the second LED beads 302 based on the brightness of the second LED beads 302 and the brightness-current curve; determine a second current compensation value based on the difference between the second brightness and the second target brightness in the previous cycle; determine the driving current of the second LED beads 302 based on the base current of the second LED beads 302 and the second current compensation value; and control the multiple second LED beads 302 to emit light using the driving current of the second LED beads 302.

[0058] The brightness control described above is performed periodically. Therefore, when compensating in this cycle, the difference between the brightness of the previous cycle and the target value can be used as a reference.

[0059] In this implementation, the brightness is compensated by the difference between the actual brightness and the target brightness in the previous cycle, thereby achieving dynamic control of the brightness and ensuring brightness uniformity and stability.

[0060] In some cases, the first control circuit 400 and the second control circuit 500 can simultaneously compensate for the inner and outer rings.

[0061] In other cases, only one of the first control circuit 400 and the second control circuit 500 performs the above-mentioned compensation.

[0062] In this embodiment of the disclosure, total brightness refers to the brightness required for AOI detection.

[0063] The brightness-current curve refers to the curve showing how the brightness of each LED, such as a light-emitting diode, changes with the current. This curve can be obtained through prior calibration.

[0064] Therefore, after determining the brightness of the LED beads, the corresponding base current can be found through this curve.

[0065] In this embodiment of the disclosure, the current compensation value can be calculated using the following formula:

[0066] Where e is the brightness deviation (target brightness) (Real-time brightness); t is time; Kp, Ki, and Kd are proportional, integral, and derivative parameters, respectively; Indicates the proportion; Indicates the integral term; This represents the differential term.

[0067] The values ​​of Kp, Ki, and Kd can be determined experimentally, and will not be elaborated here.

[0068] In this embodiment of the disclosure, the drive current is equal to the base current plus the current compensation value.

[0069] In other words, the drive current can be calculated using the following formula:

[0070] Where Iout is the drive current and Ibase is the base current.

[0071] In this embodiment of the disclosure, the first control circuit 400 is used to determine the brightness ratio of the plurality of first LED beads 301 and the plurality of second LED beads 302 based on the size of the chip to be tested; determine the brightness of the plurality of first LED beads 301 based on the brightness ratio and the total brightness; and determine the brightness of each first LED bead 301 based on the brightness of the plurality of first LED beads 301. The second control circuit 500 is used to determine the brightness ratio of the plurality of first LED beads 301 and the plurality of second LED beads 302 based on the size of the chip to be tested; to determine the brightness of the plurality of second LED beads 302 based on the brightness ratio and the total brightness; and to determine the brightness of each second LED bead 302 based on the brightness of the plurality of second LED beads 302.

[0072] In this implementation, the brightness ratio of the inner and outer rings is determined based on the different sizes of the chips to be tested. The brightness of the first LED bead 301 and the second LED bead 302 is then determined according to this ratio, so that the backlight can be applied to optical testing scenarios of chips of different sizes.

[0073] After determining the different sizes of the chips to be tested, different allocation ratios can be determined, and then calculated according to the following formula: Ltotal = α1·L1 + α2·L2; Where Ltotal is the total brightness, α1 is the inner ring ratio, α2 is the outer ring ratio, L1 is the inner ring brightness, and L2 is the outer ring brightness.

[0074] In this embodiment of the disclosure, both the first control circuit and the second control circuit can be proportional-integral-derivative (PID) controllers.

[0075] In this embodiment of the disclosure, when the size of the chip to be tested only covers the plurality of first LED beads 301, the brightness of the plurality of first LED beads 301 is much greater than the brightness of the plurality of second LED beads 302.

[0076] At this point, α1 is much larger than α2, for example, α1 is more than 100 times α2.

[0077] The chip under test is a small chip (covering only the inner ring area): the PID algorithm in the second control circuit locks the low power output of the outer ring (no compensation is needed), and the outer ring maintains a very small current for background supplementary lighting; the first control circuit enables the inner ring PID algorithm compensation, and the inner ring is the main illumination source.

[0078] When the size of the chip to be tested covers the plurality of first LED beads 301 and part of the second LED beads 302, the brightness of the plurality of first LED beads 301 is greater than the brightness of the plurality of second LED beads 302.

[0079] At this point, α1 is greater than α2, but the difference is not as large as in the first case; for example, α1 is less than twice α2.

[0080] The chip under test is a medium-sized chip (covering the inner ring + a small amount of the outer ring transition area): both the first and second control circuits use PID algorithm compensation to dynamically cancel the brightness superposition of the overlapping areas of the inner and outer rings.

[0081] When the size of the chip to be tested completely covers the plurality of first LED beads 301 and the plurality of second LED beads 302, the brightness of the plurality of first LED beads 301 is not greater than the brightness of the plurality of second LED beads 302.

[0082] At this point, α1 is less than or equal to α2.

[0083] The chip under test is a large chip (completely covering the inner and outer rings): the inner and outer rings operate at high power through dual channels, and both the first and second control circuits use PID algorithm compensation.

[0084] After determining the total brightness, the brightness of each LED is determined based on the number of LEDs in the inner or outer ring.

[0085] The effect of the backlight provided in this embodiment is illustrated by comparing it with a control group backlight. The difference between the control group backlight and the backlight in this application is that the inner and outer ring distribution is eliminated, and all rings are evenly spaced. The comparison effect is explained below: 1. Optical interference level: Control group: The radial spacing of the multi-layered dense rings is small, and the light emission of adjacent multi-layered LEDs overlaps over a large area. The superposition of multiple brightness levels easily forms a ring of light and dark bands, requiring complex algorithms to continuously correct the crosstalk deviation between layers. This embodiment of the invention consists of only two large rings, an inner and an outer ring, with a fixed radial isolation distance between them. This significantly reduces the overlapping area of ​​light rays, naturally reduces brightness superposition interference, and only requires simple weight compensation to offset the brightness difference in the transition area, resulting in stronger optical uniformity and stability.

[0086] 2. Debugging and Operation Level: Control group: There are many layers, and each layer has independent PID adjustment parameters. During debugging, the parameters need to be calibrated and tuned layer by layer. The total number of parameters is large and the modification is cumbersome. Recalibration is time-consuming when changing chip specifications. This disclosed embodiment requires only two independent control channels (internal and external) and only two sets of PID parameters, significantly reducing the workload of calibration, modification, and maintenance, and significantly improving the efficiency of production line debugging.

[0087] 3. Hardware cost and reliability: Control group: Multi-layered circuits correspond to multiple independent driver chips and multiple power supply lines. The printed circuit board (PCB) has complex wiring, a large number of components, high hardware cost, and is prone to electrical crosstalk. The embodiments disclosed herein feature only two sets of driving circuits, resulting in simple PCB wiring, halving the number of driving components, reducing material costs, lower risk of circuit crosstalk, and lower failure rate of the light source during long-term operation.

[0088] 4. Process adaptation efficiency (AOI production lines require frequent switching between different chip sizes): Control group: The multi-layer subdivision mode requires refitting the multi-layer brightness compensation curve every time the mode is changed; This embodiment of the disclosure allows for quick matching of substrates of different sizes by adjusting only the two sets of currents in the inner and outer rings, resulting in faster model changeover and adaptation.

[0089] Figure 3 This is a flowchart illustrating a backlight control method provided in an embodiment of this disclosure. The method is applicable to... Figure 1 and Figure 2 The backlight shown is shown in the image. Figure 3 The method includes: S11. Detect the first brightness at the plurality of first LED beads 301; detect the second brightness at the plurality of second LED beads 302.

[0090] S12. Determine the brightness of each of the first LED beads 301 based on the total brightness; determine the brightness of each of the second LED beads 302 based on the total brightness.

[0091] S13. Determine the base current of the first LED bead 301 based on its brightness and brightness-current curve; determine the base current of the second LED bead 302 based on its brightness and brightness-current curve.

[0092] S14. Based on the difference between the first brightness and the first target brightness in the previous cycle, determine the first current compensation value; based on the difference between the second brightness and the second target brightness in the previous cycle, determine the second current compensation value.

[0093] S15. Determine the driving current of the first lamp bead 301 based on the base current of the first lamp bead 301 and the first current compensation value; determine the driving current of the second lamp bead 302 based on the base current of the second lamp bead 302 and the second current compensation value.

[0094] S16. The driving current of the first LED bead 301 is used to control the light emission of the plurality of first LED beads 301; the driving current of the second LED bead 302 is used to control the light emission of the plurality of second LED beads 302.

[0095] In this embodiment, the LEDs are distributed in two regions: an inner ring (first LED) and an outer ring (second LED). A larger isolation gap is reserved between the inner and outer rings, significantly reducing the area of ​​light overlap and naturally reducing brightness superposition interference. Simultaneously, the inner and outer rings are controlled by separate control circuits. Due to the reduced superposition interference, only simple weight compensation is needed to offset the brightness difference in the transition area between the inner and outer rings, resulting in stronger optical uniformity and stability. This backlight technology, with its independent control of the inner and outer rings, can flexibly adapt to different chip sizes and detection requirements, offering better adjustability for brightness uniformity.

[0096] Furthermore, by using the difference between the actual brightness and the target brightness from the previous cycle, brightness is compensated to achieve dynamic control of brightness, thereby ensuring brightness uniformity and stability.

[0097] In this embodiment of the disclosure, the brightness of each of the first LED beads 301 is determined based on the total brightness; the brightness of each of the second LED beads 302 is determined based on the total brightness, including: Based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads 301 and the plurality of second LED beads 302 is determined; based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads 301 and the plurality of second LED beads 302 is determined. The brightness of the plurality of first LED beads 301 is determined based on the brightness ratio and the total brightness; the brightness of the plurality of second LED beads 302 is determined based on the brightness ratio and the total brightness. The brightness of each first LED bead 301 is determined based on the brightness of the plurality of first LED beads 301; the brightness of each second LED bead 302 is determined based on the brightness of the plurality of second LED beads 302.

[0098] In this implementation, the brightness ratio of the inner and outer rings is determined based on the different sizes of the chips to be tested. The brightness of the first LED bead 301 and the second LED bead 302 is then determined according to this ratio, so that the backlight can be applied to optical testing scenarios of chips of different sizes.

[0099] For a detailed explanation of the above steps, please refer to the structure section above; it will not be repeated here.

[0100] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A backlight source for optical inspection, characterized in that, The backlight source includes: a stage (100), a backlight panel (200), multiple LED beads (300), a first control circuit (400), and a second control circuit (500); The backlight panel (200) is located on the stage (100), and the backlight panel (200) has a groove (201). The plurality of LED beads (300) includes a plurality of first LED beads (301) and a plurality of second LED beads (302) arranged at the bottom of the groove (201). The plurality of first LED beads (301) are arranged in multiple rings in the middle of the groove (201), and the plurality of second LED beads (302) are arranged in multiple rings at the edge of the groove (201). The distance D1 between an adjacent ring of first LED beads (301) and a ring of second LED beads (302) is greater than the distance D2 between two adjacent rings of first LED beads (301), and the distance D1 between an adjacent ring of first LED beads (301) and a ring of second LED beads (302) is greater than the distance D3 between two adjacent rings of second LED beads (302). The first control circuit (400) is electrically connected to the plurality of first lamp beads (301) respectively, and is used to control the brightness of the plurality of first lamp beads (301); The second control circuit (500) is electrically connected to the plurality of second lamp beads (302) respectively, and is used to control the brightness of the plurality of second lamp beads (302).

2. The backlight according to claim 1, characterized in that, The spacing D1 between adjacent rings of the first LED (301) and the second LED (302) is 6.5~7.5mm; The spacing D2 between two adjacent rings of the first LED beads (301) is 5.5~6.5mm; The spacing D3 between two adjacent rings of the second LED (302) is 5.5~6.5mm.

3. The backlight according to claim 1, characterized in that, The backlight also includes: a reflective layer (600). The reflective layer (600) is attached to the sidewall of the groove (201).

4. The backlight according to claim 3, characterized in that, The reflective layer (600) is a reflective BOPP layer.

5. The backlight according to claim 4, characterized in that, The thickness of the reflective layer (600) is 0.05~0.07mm.

6. The backlight source according to any one of claims 1 to 5, characterized in that, The backlight also includes: a first brightness sensor (700) and a second brightness sensor (800); The first brightness sensor (700) is used to detect the first brightness at the plurality of first LED beads (301); The second brightness sensor (800) is used to detect the second brightness at the plurality of second LED beads (302); The first control circuit (400) is used to determine the brightness of each of the first LED beads (301) based on the total brightness; determine the base current of the first LED beads (301) based on the brightness of the first LED beads (301) and the brightness-current curve; determine the first current compensation value based on the difference between the first brightness and the first target brightness in the previous cycle; determine the driving current of the first LED beads (301) based on the base current of the first LED beads (301) and the first current compensation value; and control the multiple first LED beads (301) to emit light using the driving current of the first LED beads (301). The second control circuit (500) is used to determine the brightness of each second LED bead (302) based on the total brightness; determine the base current of the second LED bead (302) based on the brightness of the second LED bead (302) and the brightness-current curve; determine the second current compensation value based on the difference between the second brightness and the second target brightness in the previous cycle; determine the driving current of the second LED bead (302) based on the base current of the second LED bead (302) and the second current compensation value; and control the multiple second LED beads (302) to emit light using the driving current of the second LED bead (302).

7. The backlight according to claim 6, characterized in that, The first control circuit (400) is used to determine the brightness ratio of the plurality of first LED beads (301) and the plurality of second LED beads (302) based on the size of the chip to be tested; and to determine the brightness of the plurality of first LED beads (301) based on the brightness ratio and the total brightness. The brightness of each of the first LED beads (301) is determined based on the brightness of the plurality of first LED beads (301); The second control circuit (500) is used to determine the brightness ratio of the plurality of first LED beads (301) and the plurality of second LED beads (302) based on the size of the chip to be tested; to determine the brightness of the plurality of second LED beads (302) based on the brightness ratio and the total brightness; and to determine the brightness of each second LED bead (302) based on the brightness of the plurality of second LED beads (302).

8. The backlight according to claim 7, characterized in that, When the size of the chip to be tested only covers the plurality of first LED beads (301), the brightness of the plurality of first LED beads (301) is much greater than the brightness of the plurality of second LED beads (302); When the size of the chip to be tested covers the plurality of first LED beads (301) and part of the second LED beads (302), the brightness of the plurality of first LED beads (301) is greater than the brightness of the plurality of second LED beads (302); When the size of the chip to be tested completely covers the plurality of first LED beads (301) and the plurality of second LED beads (302), the brightness of the plurality of first LED beads (301) is not greater than the brightness of the plurality of second LED beads (302).

9. A control method for a backlight source according to any one of claims 1 to 5, characterized in that, The method includes: The first brightness at the plurality of first LED beads (301) is detected; the second brightness at the plurality of second LED beads (302) is detected; The brightness of each of the first LED beads (301) is determined based on the total brightness; the brightness of each of the second LED beads (302) is determined based on the total brightness; Based on the brightness of the first LED (301) and its brightness-current curve, the base current of the first LED (301) is determined; based on the brightness of the second LED (302) and its brightness-current curve, the base current of the second LED (302) is determined. Based on the difference between the first brightness and the first target brightness in the previous cycle, a first current compensation value is determined; based on the difference between the second brightness and the second target brightness in the previous cycle, a second current compensation value is determined. The driving current of the first LED (301) is determined based on the base current of the first LED (301) and the first current compensation value; the driving current of the second LED (302) is determined based on the base current of the second LED (302) and the second current compensation value. The driving current of the first LED (301) is used to control the light emission of the plurality of first LEDs (301); the driving current of the second LED (302) is used to control the light emission of the plurality of second LEDs (302).

10. The method according to claim 9, characterized in that, The brightness of each of the first LED beads (301) is determined based on the total brightness; The brightness of each of the second LED beads (302) is determined based on the total brightness, including: Based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads (301) and the plurality of second LED beads (302) is determined; based on the size of the chip to be tested, the brightness ratio of the plurality of first LED beads (301) and the plurality of second LED beads (302) is determined. The brightness of the plurality of first LED beads (301) is determined based on the brightness ratio and the total brightness; the brightness of the plurality of second LED beads (302) is determined based on the brightness ratio and the total brightness. The brightness of each first LED (301) is determined based on the brightness of the plurality of first LEDs (301); the brightness of each second LED (302) is determined based on the brightness of the plurality of second LEDs (302).

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