A Micro-LED light-emitting chip testing method

Abstract

A method for testing a Micro-LED light-emitting chip relates to the field of Micro-LED display technology, and solves the problem of uneven brightness matching of red, green and blue LEDs, resulting in excessive grayscale unevenness and brightness unevenness, when the existing AM driving technology using TFT drives the Micro-LED display due to the performance difference between TFT and LED. The method designs a Micro-LED test array module based on a PCB substrate, connects the LED array in parallel inside the array, and directly drives the LED externally using a voltage source to ensure that the voltage loaded on each LED is consistent. By testing the data voltage of the red, green and blue primary color Micro-LED array module from 0 grayscale to 255 grayscale, the common divisor of the minimum grayscale voltage of the red, green and blue modules and the minimum grayscale level of the Micro-LED white field are calculated. The present invention is applicable to the field of Micro-LED display.

Description

Technical Field

[0001] The present invention belongs to the field of Micro-LED display technology, and in particular relates to a Micro-LED light-emitting chip testing method. Background Art

[0002] As a new generation of display technology, Micro-LED display combines the advantages of self-luminescence, low power consumption, high contrast, high brightness, ultra-high resolution and high color saturation, high response speed and long life. Compared with organic light emitting diodes (OLED), Micro-LED, as an inorganic light-emitting device, has a longer life and can achieve higher display brightness. Compared with Mini-LED technology, Micro-LED can achieve pixel-level dimming and thinner displays.

[0003] Based on the above factors, Micro-LED is regarded as a highly promising next-generation display technology. Micro-LED display cannot be manufactured on a printed circuit board (PCB) of a passive matrix (PM) driver to achieve ultra-small dot pitch, high density, and low-cost preparation; Micro-LED display cannot be manufactured on a large area using silicon-based semiconductors. The use of TFT to realize Micro-LED preparation can achieve ultra-small pixel size, ultra-high density display, low cost, and large-size display. However, when using TFT's AM driving technology to drive Micro-LED displays, the performance difference between TFT and LED will cause uneven brightness matching of red, green, and blue LEDs, resulting in excessive grayscale unevenness and brightness unevenness. The reason for excessive grayscale unevenness of LED display is that the output drive current or modulation pulse width step accuracy of the drive control system for each grayscale of red, green, and blue does not meet the requirements, and cannot be output according to the step accuracy required by the actual light-emitting chip, resulting in excessive deviation between a certain level and the previous and next levels, and excessive grayscale unevenness in the Micro-LED display. The current method to solve the excessive unevenness of grayscale display is to adjust the output accuracy of the drive control system for each level of red, green, and blue to meet the brightness requirements required for each level of output. However, the photoelectric characteristics of different LEDs are different, and the required control accuracy is also different. The current industry has not conducted research on matching LED characteristics and control systems to address this issue. In order to achieve uniform grayscale transition and highly uniform display of Micro-LED, it is necessary to study the characteristics of Micro-LED devices in order to design pixel circuits and drive architectures that match them and achieve high-definition display. Summary of the invention

[0004] The present invention solves the problem that when the existing TFT AM driving technology is used to drive the Micro-LED display, the performance difference between TFT and LED will cause uneven matching of the brightness of the red, green and blue LEDs, resulting in excessive grayscale unevenness and brightness unevenness. Therefore, a Micro-LED light-emitting chip testing method is proposed. According to the testing method, the minimum grayscale level N of the Micro-LED white field is obtained, so that the Micro-LED display depth is set to N bits to better overcome the problem of excessive grayscale unevenness of the Micro-LED, which provides an important reference value for the subsequent improvement of the Micro-LED display quality.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a Micro-LED light-emitting chip testing method, the testing method comprising the following steps:

[0007] Step 1: Design Micro-LED test array module based on PCB substrate;

[0008] Step 2: Connect the red, green and blue LED arrays in parallel inside the array;

[0009] Step 3: Set the voltage source to start from 0V and increase by 0.01V each time until it reaches the set maximum voltage V, record the brightness value every time the voltage increases, and record the corresponding current value at the same time;

[0010] Step 4: Extract the highest target brightness measured value and the lowest target brightness measured value corresponding to the three types of Micro-LED modules of red, green and blue and their corresponding voltage value data respectively;

[0011] Step 5: Obtain the data voltage increment for each gray level through the data voltage corresponding to the highest brightness and the data voltage corresponding to the lowest brightness;

[0012] Step 6: Obtain the data voltage of each grayscale level of the red, green and blue Micro-LED display module according to the data voltage increment of each grayscale level, and calculate the common divisor of the minimum grayscale voltage of the red, green and blue modules ;

[0013] Step 7: Based on the common divisor of the minimum grayscale voltage of the red, green and blue modules Get the corresponding minimum grayscale;

[0014] Step 8: Select the maximum value of the data voltage increment for each gray level of red, green and blue , combined with the minimum grayscale, we get the minimum grayscale level of the Micro-LED white field.

[0015] Furthermore, there is a preferred embodiment that uses an external voltage source to directly drive the Micro-LED test array module, thereby ensuring that the voltage loaded on each LED is consistent.

[0016] Furthermore, in a preferred embodiment, the red, green and blue target brightness ratio is 6:3:1.

[0017] Further, in another preferred embodiment, step 1 is specifically as follows:

[0018] M × N pixel array modules are designed based on the PCB substrate, and the M × N arrays are connected in parallel.

[0019] Furthermore, in another preferred embodiment, the actual measured values ​​of the highest target brightness corresponding to the three types of Micro-LED modules in step 4 are respectively cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V.

[0020] Furthermore, in another preferred embodiment, the actual measured values ​​of the minimum target brightness corresponding to the three types of Micro-LED modules in step 4 are respectively cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V.

[0021] Furthermore, in another preferred embodiment, the data voltage increment for each gray level in step 5 is:

[0022] ;

[0023] ;

[0024] .

[0025] Furthermore, in another preferred embodiment, in step 6, the data voltages of each gray level of the red, green, and blue Micro-LED display modules are respectively:

[0026] R: mV / gray;

[0027] G: mV / gray;

[0028] B: mV / gray.

[0029] Furthermore, there is another preferred embodiment, in step 7, the minimum grayscale is mV / gray.

[0030] Furthermore, in another preferred embodiment, the minimum grayscale level of the Micro-LED white field in step 8 is:

[0031] ;

[0032] in, Represents an integer.

[0033] The beneficial effects of the present invention are:

[0034] 1. The present invention provides a method for testing a Micro-LED light-emitting chip. A Micro-LED test array module is designed based on a PCB substrate. The LED array is connected in parallel inside the array, and a voltage source is used externally to directly drive the LED to ensure that the voltage loaded on each LED is consistent, thereby eliminating the influence of the AM TFT pixel driving circuit.

[0035] Furthermore, the test method of the present invention obtains that the data voltages of the red, green and blue primary color Micro-LED array module from grayscale 0 to grayscale 255 under the conditions of white field target brightness of L cd / m2 and YK color temperature are respectively V. V and V. Then the minimum grayscale voltage is R: mV / gray, G: mV / gray, B: mV / gray, the common divisor of the minimum grayscale voltage of the red, green and blue modules is calculated as , then the corresponding minimum grayscale is mV / gray. Then select V. V and Maximum value of V , so the minimum grayscale level of the Micro-LED white field can be obtained as Therefore, the Micro-LED display depth of N bits can better overcome the excessive grayscale non-uniformity of Micro-LED, which provides an important reference value for the subsequent improvement of Micro-LED display quality.

[0036] The present invention is applicable to the field of Micro-LED display. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 This is the wiring diagram of the red lamp bead test module of the present invention;

[0039] Figure 2 This is the wiring diagram of the green lamp bead test module described in the present invention;

[0040] Figure 3 This is the wiring diagram of the blue lamp bead test module of the present invention;

[0041] Figure 4 It is a schematic diagram of the test experiment described in the present invention;

[0042] Figure 5 It is the red, green and blue module data voltage described in the present invention. DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can be made without departing from the concept of the present invention.

[0044] Implementation method 1. This implementation method provides a Micro-LED light-emitting chip testing method. According to the testing method, the minimum grayscale level N of the Micro-LED white field is obtained, so that the Micro-LED display depth is set to N bits to better overcome the problem of excessive grayscale non-uniformity of the Micro-LED, which provides important reference value for subsequent improvement of the Micro-LED display quality.

[0045] The testing method comprises the following steps:

[0046] Step 1: Design Micro-LED test array module based on PCB substrate;

[0047] Specifically:

[0048] Based on the PCB substrate, an M × N pixel array module is designed, and the M × N arrays are connected in parallel. The size of M and N needs to be determined according to the measurement equipment used. The value range of M and N and the number of arrays set according to the area size of conventional test equipment are shown in Table 1 below.

[0049] Table 1

[0050]

[0051] Step 2: The red, green and blue LED arrays are connected in parallel inside the Micro-LED test array module;

[0052] Specifically:

[0053] The red, green and blue LED beads are bonded to the substrate by a die bonding machine, and the red, green and blue LED arrays are connected in parallel to form a Figures 1 to 3 The test module wiring diagram is shown.

[0054] Step 3: Set the voltage source to start from 0V and increase by 0.01V each time until it reaches the set maximum voltage V, record the brightness value every time the voltage increases, and record the corresponding current value at the same time;

[0055] Specifically:

[0056] Set the voltage source output mode, starting from 0V and increasing by 0.01V each time, up to V; among which, the highest value The value is determined by the actual measured parameters of the light-emitting chip. In order to prevent the voltage from being too high and burning the test module, the voltage must be guaranteed to achieve the highest brightness value. For red light, it is from 1.5V to 2.0V, for green light, it is from 1.8V to 2.1V, and for blue light, it is from 2.1V to 2.6V.

[0057] Step 4: Extract the highest target brightness measured value and the lowest target brightness measured value corresponding to the three types of Micro-LED modules of red, green and blue and their corresponding voltage value data respectively;

[0058] Specifically:

[0059] The actual measured values ​​of the highest target brightness corresponding to the three types of Micro-LED modules are: cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V.

[0060] The measured minimum target brightness values ​​of the three Micro-LED modules, red, green and blue, are respectively cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V.

[0061] Step 5: Obtain the data voltage increment for each gray level through the data voltage corresponding to the highest brightness and the data voltage corresponding to the lowest brightness;

[0062] Specifically:

[0063] The data voltage increments for each grayscale level of the three types of Micro-LED modules, red, green and blue, are: ;

[0064] ;

[0065] .

[0066] Step 6: Obtain the data voltage of each grayscale level of the red, green and blue Micro-LED display module according to the data voltage increment of each grayscale level, and calculate the common divisor of the minimum grayscale voltage of the red, green and blue modules ;

[0067] Among them, the data voltage of each gray level of the red, green and blue Micro-LED display module is:

[0068] R: mV / gray;

[0069] G: mV / gray;

[0070] B: mV / gray.

[0071] Step 7: Based on the common divisor of the minimum grayscale voltage of the red, green and blue modules Get the corresponding minimum grayscale;

[0072] Among them, the minimum grayscale is expressed as: mV / gray.

[0073] Step 8: Select the maximum value of the data voltage increment for each gray level of red, green and blue , combined with the minimum grayscale, we get the minimum grayscale level of the Micro-LED white field.

[0074] Among them, the minimum grayscale level of Micro-LED white field is:

[0075] ;

[0076] in, Represents an integer.

[0077] Finally, by using the N bits driving control system to drive the red, green and blue LED chips, they can accurately emit light at low gray levels. cd / m 2 , cd / m 2 and cd / m 22 The brightness is completed by the ratio of 6:3:1 to achieve the minimum brightness L MIN cd / m 2 , YK color temperature white field display. At the same time, it can accurately emit cd / m 2 , cd / m 2 and cd / m 2 The brightness is completed by a 6:3:1 ratio to achieve the highest brightness L MAX cd / m 2 , YK color temperature white field display. This can realize the Micro-LED display from low gray L MIN cd / m 2 To highlight L MAX cd / m 2 There is no color cast in the grayscale transition and the display is uniform.

[0078] Embodiment 2: This embodiment adopts an external voltage source to directly drive the Micro-LED test array module based on the Micro-LED light emitting chip testing method described in Embodiment 1.

[0079] Using an external voltage source to directly drive the Micro-LED test array module can ensure that the voltage loaded on each LED is consistent.

[0080] Implementation method three, see Figure 4 and Figure 5 This embodiment is described. This embodiment specifically describes a method for testing a Micro-LED light-emitting chip described in Embodiment 1.

[0081] The experimental system is set up as follows Figure 4As shown, the Micro-LED test module is placed on the test bench of LED626, and the positive and negative poles of the power signal are directly loaded to the V data and GND, the parameters of Micro-LED are directly measured by LED626, and the obtained voltage, current and brightness data are saved by computer.

[0082] The target brightness setting of the Micro-LED display is L MAX cd / cm 2 , the minimum brightness is L MIN cd / m 2 , color temperature is YK, L MAX cd / cm 2 and L MIN cd / m 2 The color temperature value is set according to the application scenario, generally for outdoor use and indoor use. Since the human eye has different sensitivities to screen brightness outdoors and indoors due to ambient light, the set values ​​are shown in Table 2 below.

[0083] Table 2

[0084]

[0085] The target brightness ratio of red, green and blue is 6:3:1, as shown in Table 3 and Table 4 below.

[0086] Table 3

[0087]

[0088] Table 4

[0089]

[0090] The entire test process is as follows:

[0091] Step 1: Set the voltage source output mode, starting from 0V and increasing by 0.01V each time, up to V. Each time the voltage increases, the brightness value is recorded, and the corresponding current value is recorded at the same time. Among them, the highest value The value is determined by the actual measured parameters of the light-emitting chip. In order to prevent the voltage from being too high and burning the test module, the voltage must be guaranteed to achieve the highest brightness value. For red light, it is from 1.5V to 2.0V, for green light, it is from 1.8V to 2.1V, and for blue light, it is from 2.1V to 2.6V.

[0092] Step 2: Extract the highest target brightness values ​​corresponding to the three types of Micro-LED modules, red, green and blue, according to step 1 cd / m 2 , cd / m2 and cd / m 2 And the corresponding voltage value data V. V and V.

[0093] Step 3: Extract the minimum target brightness values ​​corresponding to the three types of Micro-LED modules, red, green and blue, according to step 1 cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data V. V and V.

[0094] The test results of the red, green and blue Micro-LED modules are shown in Tables 5 and 6 below.

[0095] Table 5

[0096]

[0097] Table 6

[0098]

[0099] Assume that the white field brightness changes linearly with the data voltage, and the highest brightness of the target white field corresponds to grayscale level 255, then the lowest brightness of the target white field is grayscale level 1. Then the data voltage increments for each grayscale level are obtained by using the data voltage corresponding to the highest brightness and the data voltage corresponding to the lowest brightness. , , Substituting the above data into the formula , we can get the data voltage of each gray level of the red, green and blue Micro-LED display module as R: mV / gray, G: mV / gray, B: mV / gray, e.g. Figure 5 As shown. By calculation, the common divisor of the minimum grayscale voltage of the red, green and blue modules is , then the corresponding minimum grayscale is mV / gray. Then select V. V and Maximum value of V , so the minimum grayscale level of the Micro-LED white field can be obtained as Therefore, the Micro-LED display depth of N bits can better overcome the excessive grayscale non-uniformity of Micro-LED.

[0100] Furthermore, by using an N-bit drive control system, the red, green, and blue LED chips can be accurately emitted at low gray levels. cd / m 2 , cd / m 2 and cd / m 22 The brightness is completed by the ratio of 6:3:1 to achieve the minimum brightness L MIN cd / m 2 , YK color temperature white field display. At the same time, it can accurately emit cd / m 2 , cd / m 2 and cd / m 2 The brightness is completed by a 6:3:1 ratio to achieve the highest brightness L MAX cd / m 2 , YK color temperature white field display. This can realize the Micro-LED display from low gray L MIN cd / m 2 To highlight L MAX cd / m 2 There is no color cast in the grayscale transition and the display is uniform.

[0101] In the above description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0102] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may be modified and varied in various ways.

Claims

1. A Micro-LED light-emitting chip testing method, characterized in that: The method is: Step 1: Design Micro-LED test array module based on PCB substrate; Step 2: Connect the red, green and blue LED arrays in parallel inside the array; Step 3: Set the voltage source to start from 0V and increase by 0.01V each time until it reaches the set maximum voltage V, record the brightness value every time the voltage increases, and record the corresponding current value at the same time; Step 4: Extract the highest target brightness measured value and the lowest target brightness measured value corresponding to the three types of Micro-LED modules of red, green and blue and their corresponding voltage value data respectively; The measured maximum target brightness values ​​for the three Micro-LED modules are: cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V; The measured minimum target brightness values ​​for the three Micro-LED modules are: cd / m 2 , cd / m 2 and cd / m 2 And the corresponding voltage value data are V. V and V; Step 5: Obtain the data voltage increment for each gray level through the data voltage corresponding to the highest brightness and the data voltage corresponding to the lowest brightness; The data voltage increment for each gray level is: ； ； ； Step 6: Obtain the data voltage of each grayscale level of the red, green and blue Micro-LED display module according to the data voltage increment of each grayscale level, and calculate the common divisor of the minimum grayscale voltage of the red, green and blue modules ; The data voltages for each grayscale level of the red, green, and blue Micro-LED display modules are: R: mV / gray; G: mV / gray; B: mV / gray; Step 7: Based on the common divisor of the minimum grayscale voltage of the red, green and blue modules Get the corresponding minimum grayscale; The minimum grayscale is: mV / gray; Step 8: Select the maximum value of the data voltage increment for each gray level of red, green and blue , combined with the minimum grayscale, the minimum grayscale level of the Micro-LED white field is obtained; The minimum grayscale level of Micro-LED white field is: ； in, Represents an integer.

2. A Micro-LED light emitting chip testing method according to claim 1, characterized in that: An external voltage source is used to directly drive the Micro-LED test array module.

3. A Micro-LED light emitting chip testing method according to claim 1, characterized in that: The red, green and blue target brightness ratio is 6:3:

1.

4. A Micro-LED light emitting chip testing method according to claim 1, characterized in that: Step 1 is as follows: M × N pixel array modules are designed based on the PCB substrate, and the M × N arrays are connected in parallel.

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