CN105974616A - Method and system for detecting defect of LCD screen - Google Patents

Abstract

Embodiments of the present invention provide a method and system for detecting defects of a liquid crystal screen, wherein the method includes: the main chip of the test board receives the picture displayed on the liquid crystal screen to be tested from the image acquisition device; After the liquid crystal screen to be tested enters the preset picture, the actual picture displayed by the liquid crystal screen to be tested; the main chip of the test board judges whether there is a pixel whose pixel brightness is greater than the first order brightness in the displayed picture point, or, whether there is a pixel point whose pixel brightness is less than the second-order brightness in the displayed picture, and the first-order brightness is greater than the second-order brightness; if it exists, the main chip of the test board passes the indication The light indicates that the LCD screen under test is defective. The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

Description

Method and system for detecting liquid crystal screen defects

technical field

Embodiments of the present invention relate to the technical field of liquid crystal screens, in particular to a method and system for detecting defects of liquid crystal screens.

Background technique

Nowadays, most display devices use LCD screens, but limited by the manufacturing process, LCD screens often have defects. Therefore, during the production process of LCD screens, LCD screens must be inspected to detect defective LCD screens to ensure product quality.

Defects of LCD screens usually refer to the existence of dead pixels, bad lines and bad spots on the LCD screen. Specifically, it is divided into bad pixels, bad lines, and bad spots that are always bright, and bad pixels, bad lines, and bad spots that are always dark.

The detection method of the constant bright defect is to input a black screen to the LCD screen, and detect whether there are bright spots, bright lines or bright spots on the LCD screen through manual visual inspection. If so, the LCD screen is defective.

The inspection method for normally dark defects is similar to that for normally bright defects. Input a white screen to the LCD screen, and check whether there are dark spots, dark lines or dark spots on the LCD screen through manual visual inspection. If so, the LCD screen is defective.

Detecting whether there is a defect in the LCD screen by manual visual inspection is inefficient and prone to missed inspections.

Contents of the invention

Embodiments of the present invention provide a method and system for detecting defects of a liquid crystal screen, which are used to solve the problems of low efficiency and prone to missed detection in the existing manual visual inspection method.

An embodiment of the present invention provides a method for detecting defects of a liquid crystal screen, including:

The main chip of the test board receives the picture displayed by the liquid crystal screen to be tested from the image acquisition device; screen;

The main chip of the test board judges whether there are pixels whose pixel brightness is higher than the first-order brightness in the displayed picture, or whether there are pixels whose pixel brightness is lower than the second-order brightness in the displayed picture, and the The first-level brightness is greater than the second-level brightness;

If it exists, the main chip of the test board indicates that the liquid crystal screen to be tested has a defect through an indicator light.

Correspondingly, an embodiment of the present invention also provides a liquid crystal screen defect detection system, including:

An image acquisition device, which is used to collect the actual picture displayed by the liquid crystal screen to be tested after inputting a preset picture to the liquid crystal screen to be tested;

The test board includes a main chip, and the main chip includes:

The picture receiving module is used to receive the actual picture displayed on the liquid crystal screen to be tested from the image acquisition device;

A pixel judging module, configured to judge whether there are pixels whose pixel brightness is higher than the first-order brightness in the displayed actual picture, or whether there are pixels whose pixel brightness is lower than the second-order brightness in the displayed actual picture, The first-level brightness is greater than the second-level brightness;

The defect indication module is used to indicate by indicating if there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or if there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture. The light indicates that the LCD screen under test is defective. The liquid crystal screen defect detection method and system provided by the embodiments of the present invention input a preset picture to the liquid crystal screen to be tested, use an image acquisition device to collect the actual picture displayed on the liquid crystal screen to be tested, and transmit the collected actual picture to the Test board, the main chip of the test board has the function of automatically obtaining the pixel brightness of each pixel in the actual picture, the main chip of the test board compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness, or Compare the pixel brightness of each pixel in the actual picture with the preset second-level brightness. If there are pixels in the actual picture whose pixel brightness is greater than the first-level brightness, or pixels whose pixel brightness is lower than the second-level brightness, Then the main chip of the test board determines that there is a defect in the liquid crystal screen to be tested, and indicates it through an indicator light. The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

FIG. 1 is a flow chart of the steps of a method for detecting defects of a liquid crystal screen in Embodiment 1 of the present invention;

FIG. 2 is a flow chart of the steps of a method for detecting defects of a liquid crystal screen in Embodiment 2 of the present invention;

3 is a schematic diagram of a design framework of a method for detecting defects of a liquid crystal screen in Embodiment 2 of the present invention;

4 is a schematic structural diagram of a liquid crystal screen defect detection system in Embodiment 3 of the present invention;

FIG. 5 is a schematic structural diagram of a liquid crystal screen defect detection system in Embodiment 4 of the present invention.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Embodiment one

A liquid crystal screen defect detection method proposed in Embodiment 1 of the present invention is introduced in detail.

The liquid crystal screen in the embodiment of the present invention can be the liquid crystal screen in TV or display, and the main chip of TV or display has the function of automatically obtaining the intensity of input signal, and main chip can obtain the strength range of the signal in the designated area of liquid crystal screen, including the maximum brightness and minimum brightness. For example, for an LCD screen with a physical resolution of 1920X1080, you can input a specific picture for the entire LCD screen area (1920X1080 display area), and judge whether the LCD screen is defective by reading the maximum brightness and minimum brightness of this area. Moreover, the data of maximum brightness and minimum brightness can be stored in the register of the main chip.

Referring to FIG. 1 , it shows a flow chart of steps of a liquid crystal screen defect detection method in Embodiment 1 of the present invention.

Step 100, inputting a preset picture to the LCD screen to be tested.

Since the liquid crystal screen is detected to detect whether there are always bright defects or normally dark defects, the preset picture can be a pure black picture or a pure white picture.

Step 102, the image acquisition device acquires the actual picture displayed on the liquid crystal screen to be tested.

The image acquisition device may be a video camera or a camera, and the embodiment of the present invention does not specifically limit the image acquisition device.

The liquid crystal screen to be tested can be photographed by an image acquisition device, and the actual picture displayed on the liquid crystal screen to be tested can be collected. Wherein, the image acquisition device can capture the actual picture in real time, and can also take the actual picture into pictures one by one.

Step 104, the main chip of the test board receives the actual picture displayed on the liquid crystal screen to be tested from the image acquisition device.

The image acquisition device can be connected with the main chip of the test board, and the image acquisition device outputs the acquired actual picture displayed on the liquid crystal screen to be tested to the main chip of the test board.

The test board may be a circuit board made for testing the liquid crystal screen to be tested, wherein the main chip may be a main chip of a TV or a display. All the work of the test board is controlled by the main chip control program.

Step 106, the main chip of the test board judges whether there are pixels whose pixel brightness is higher than the first-order brightness in the actual displayed picture, or whether there are pixels whose pixel brightness is lower than the second-order brightness in the displayed actual picture, and if so, Then execute step 108; if not, the process ends.

Wherein, the first-order brightness is greater than the second-order brightness.

The current LCD screen is usually an 8-bit screen, and the brightness range of the pixels is 0-255 steps. Level 0 means black picture, level 255 means white picture, and other levels are gray picture. For pixels with normally bright defects, the brightness is usually above 150 levels; for pixels with normally dark defects, the brightness is usually below 50 levels.

The first-level brightness and the second-level brightness in the embodiment of the present invention can be set according to actual conditions.

If it exists, then execute step 108, which can be: if there are pixels whose pixel brightness is greater than the first-level brightness in the displayed actual picture, then perform step 108; or, if there are pixels whose brightness is lower than the second-level brightness in the displayed actual picture pixel, execute step 108.

Step 108, the main chip of the test board indicates that the liquid crystal screen to be tested has a defect through an indicator light.

If there are pixels with pixel brightness greater than the brightness of the first level in the actual picture displayed, the main chip of the test board can indicate that there is a certain defect in the LCD screen to be tested through an indicator light; For pixels with second-level brightness, the main chip of the test board can indicate that there is another defect in the LCD screen to be tested through another indicator light.

The indicator light can be controlled by the general purpose input output (GPIO) of the main chip.

In summary, the liquid crystal screen defect detection method provided by the embodiment of the present invention inputs a preset picture to the liquid crystal screen to be tested, uses an image acquisition device to collect the actual picture displayed on the liquid crystal screen to be tested, and collects the actual picture obtained by the acquisition. The picture is transmitted to the test board. The main chip of the test board has the function of automatically obtaining the pixel brightness of each pixel in the actual picture. The main chip of the test board compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness. Compare, or compare the pixel brightness of each pixel in the actual picture with the preset second-level brightness, if there are pixels in the actual picture whose pixel brightness is greater than the first-level brightness, or there are pixels whose brightness is lower than the second-level brightness pixel, the main chip of the test board determines that there is a defect in the LCD screen to be tested, and indicates it through the indicator light. The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

Embodiment two

A liquid crystal screen defect detection method proposed in Embodiment 2 of the present invention will be described in detail.

The liquid crystal screen in the embodiment of the present invention can be the liquid crystal screen in TV or display, and the main chip of TV or display has the function of automatically obtaining the intensity of input signal, and main chip can obtain the strength range of the signal in the designated area of liquid crystal screen, including the maximum brightness and minimum brightness. For example, for an LCD screen with a physical resolution of 1920X1080, you can input a specific picture for the entire LCD screen area (1920X1080 display area), and judge whether the LCD screen is defective by reading the maximum brightness and minimum brightness of this area. Moreover, the data of maximum brightness and minimum brightness can be stored in the register of the main chip.

Referring to FIG. 2 , it shows a flow chart of steps of a liquid crystal screen defect detection method in Embodiment 2 of the present invention.

Step 200, inputting a preset picture to the LCD screen to be tested.

Since the liquid crystal screen is detected to detect whether there are always bright defects or normally dark defects, the preset picture can be a pure black picture or a pure white picture.

If it is detected whether there is a constant bright defect on the LCD screen, a pure black image is input to the LCD screen to be tested; if it is detected whether there is a normally dark defect on the LCD screen, a pure white image is input to the LCD screen to be tested.

In step 202, the image acquisition device acquires the actual picture displayed on the liquid crystal screen to be tested.

The image acquisition device may be a video camera or a camera, and the embodiment of the present invention does not specifically limit the image acquisition device.

The liquid crystal screen to be tested can be photographed by an image acquisition device, and the actual picture displayed on the liquid crystal screen to be tested can be collected. Wherein, the image acquisition device can capture the actual picture in real time, and can also take the actual picture into pictures one by one.

Step 204, the main chip of the test board receives the actual image displayed on the liquid crystal screen to be tested from the image acquisition device.

The image acquisition device can be connected with the main chip of the test board, and the image acquisition device outputs the acquired actual picture displayed on the liquid crystal screen to be tested to the main chip of the test board.

The test board may be a circuit board made for testing the liquid crystal screen to be tested, wherein the main chip may be a main chip of a TV or a display. All the work of the test board is controlled by the main chip control program.

Step 206, the main chip of the test board judges whether there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture, if there is, Then execute step 208; if not, execute step 210.

Wherein, the first level of brightness is greater than the second level of brightness, the first level of brightness can be set to 200 levels, and the second level of brightness can be set to 50 levels. The first-level brightness and the second-level brightness in the embodiment of the present invention can be set according to actual conditions.

The current LCD screen is usually an 8-bit screen, and the brightness range of the pixels is 0-255 steps. Level 0 means black picture, level 255 means white picture, and other levels are gray picture. For pixels with normally bright defects, the brightness is usually above 150 levels; for pixels with normally dark defects, the brightness is usually below 50 levels.

Preferably, when the preset picture is a pure black picture, the main chip of the test board judges whether there are pixels whose pixel brightness is greater than the first order brightness in the actual picture displayed; when the preset picture is a pure white picture, the test board's The main chip judges whether there are pixels with pixel brightness lower than the second-level brightness in the actual displayed picture.

If it exists, then execute step 208, which can be: if there are pixels whose pixel brightness is greater than the first-level brightness in the displayed actual picture, then perform step 208; or, if there are pixels whose brightness is lower than the second-level brightness in the displayed actual picture pixel, execute step 208.

If it does not exist, then execute step 210, which can be: if there is no pixel point with a pixel brightness greater than the first-level brightness in the displayed actual picture, and there is no pixel point with a pixel brightness lower than the second-level brightness in the displayed actual picture , then step 210 is executed.

In step 208, the main chip of the test board indicates that the liquid crystal screen to be tested has a defect through an indicator light.

If there is a pixel point with a pixel brightness greater than the first-level brightness in the actual picture displayed, the main chip of the test board can indicate that there is a constant bright defect in the LCD screen to be tested through the first indicator light; If the pixel point is less than the second-level brightness, the main chip of the test board can indicate that there is a normally dark defect in the liquid crystal screen to be tested through the second indicator light.

The indicator light can be controlled by the general purpose input output (GPIO) of the main chip.

Step 210, the main chip of the test board indicates that there is no defect in the liquid crystal screen to be tested through the third indicator light.

The above-mentioned first indicator light, second indicator light and third indicator light may be three light emitting diodes (Light Emitting Diode, LED), respectively LED1, LED2 and LED3. When LED1 is on, it means that the LCD screen to be tested has a constant bright defect; when LED2 is on, it means that the LCD screen to be tested has a normally dark defect; when LED3 is on, it means that the LCD screen to be tested has no defect.

Whether there is a defect in the liquid crystal screen to be tested can be visually determined by whether the indicator light is on, and whether the defect exists is a always bright defect or a normally dark defect.

Preferably, a serial port can be added on the test board, and the test data can be uploaded to the server of the liquid crystal screen production system through the added serial port for product tracking and management.

Wherein, the test data includes the test result of whether the liquid crystal screen to be tested has a defect; when the liquid crystal screen to be tested has a defect, the test data includes whether the liquid crystal screen to be tested has a normally bright defect or a normally dark defect.

In summary, the design frame diagram of the liquid crystal screen defect detection method provided by the embodiment of the present invention is shown in FIG. 3 . Input the preset picture to the LCD screen to be tested, use the image acquisition device to collect the actual picture displayed on the LCD screen to be tested, and transmit the collected actual picture to the test board. The main chip of the test board has the ability to automatically acquire each The function of the pixel brightness of the pixel. The main chip of the test board compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness, or compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness. The second-order brightness is compared. If there are pixels with pixel brightness greater than the first-order brightness in the actual screen, or pixels with pixel brightness lower than the second-order brightness, the main chip of the test board determines that the LCD screen to be tested is defective. And indicated by the indicator light. When there are pixels in the actual picture whose pixel brightness is higher than the first-level brightness, GPIO1 of the main chip controls LED1 to light up, indicating that the LCD screen to be tested has a constant bright defect; When there is a pixel, GPIO2 of the main chip controls LED2 to light up, indicating that the LCD screen to be tested has a normally dark defect; when there is neither a pixel with a pixel brightness greater than the first-level brightness nor a pixel with a pixel brightness lower than the second-level brightness in the actual screen. When the pixels of the first-order brightness are selected, the GPIO3 of the main chip controls the LED3 to light up, indicating that the LCD screen to be tested does not have a constant bright defect or a constant bright defect. And the test data of the LCD screen to be tested can be uploaded to the server of the production system through the serial port on the test board for product tracking and management. Wherein, all the work of the main chip can be controlled by the main chip control program. Between the serial port and the main chip, between the serial port and the server can be connected through a Universal Asynchronous Receiver/Transmitter (UART). The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

Embodiment Three

A liquid crystal screen defect detection system proposed in Embodiment 3 of the present invention is introduced in detail.

Referring to FIG. 4 , it shows a schematic structural diagram of a liquid crystal screen defect detection system in Embodiment 3 of the present invention.

The system may include: an image acquisition device 30 and a test board 32 .

Wherein, the test board 32 may include: a main chip 321 . The main chip 321 may include: a picture receiving module 3211 , a pixel judging module 3212 , and a defect indicating module 3213 .

The image collection device 30 is configured to collect the actual picture displayed by the liquid crystal screen to be tested after inputting a preset picture to the liquid crystal screen to be tested.

The picture receiving module 3211 is configured to receive the actual picture displayed on the liquid crystal screen to be tested from the image acquisition device 30 .

A pixel judging module 3212, configured to judge whether there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture , the first-level brightness is greater than the second-level brightness.

The defect indication module 3213 is configured to: if there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or, if there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture, then pass The indicator light indicates that the liquid crystal screen to be tested has a defect.

In summary, the liquid crystal screen defect detection system provided by the embodiment of the present invention inputs a preset picture to the liquid crystal screen to be tested, uses an image acquisition device to collect the actual picture displayed on the liquid crystal screen to be tested, and collects the actual The picture is transmitted to the test board. The main chip of the test board has the function of automatically obtaining the pixel brightness of each pixel in the actual picture. The main chip of the test board compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness. Compare, or compare the pixel brightness of each pixel in the actual picture with the preset second-level brightness, if there are pixels in the actual picture whose pixel brightness is greater than the first-level brightness, or there are pixels whose brightness is lower than the second-level brightness pixel, the main chip of the test board determines that there is a defect in the LCD screen to be tested, and indicates it through the indicator light. The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

Embodiment four

A liquid crystal screen defect detection system proposed in Embodiment 4 of the present invention is introduced in detail.

Referring to FIG. 5 , it shows a schematic structural diagram of a liquid crystal screen defect detection system in Embodiment 4 of the present invention.

The system may include: an image acquisition device 40 and a test board 42 .

Wherein, the test board 42 may include: a main chip 421 , a main chip control module 422 , and a serial port 423 . The main chip 421 may include: a picture receiving module 4211 , a pixel judging module 4212 , a defect indication module 4213 , a normal indication module 4214 , and a test data transmission module 4215 .

The image collection device 40 is configured to collect the actual picture displayed on the liquid crystal screen to be tested after inputting a preset picture to the liquid crystal screen to be tested.

Preferably, the preset picture is a pure black picture or a pure white picture.

The picture receiving module 4211 is used for receiving the actual picture displayed on the liquid crystal screen to be tested from the image acquisition device 40 .

A pixel judging module 4212, configured to judge whether there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture , the first-level brightness is greater than the second-level brightness.

Preferably, when the preset picture is a pure black picture, the pixel judging module 4212 is used to judge whether there are pixels with pixel brightness greater than the first-level brightness in the displayed picture; when the preset picture When it is a pure white picture, the pixel judging module 4212 is used to judge whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed picture.

The defect indication module 4213 is configured to: if there are pixels whose pixel brightness is higher than the first-level brightness in the displayed actual picture, or, if there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture, then pass The indicator light indicates that the liquid crystal screen to be tested has a defect.

Preferably, if the defect indication module 4213 has a pixel whose pixel brightness is greater than the first-level brightness in the displayed picture, it will use the first indicator light to indicate that there is a constant bright defect in the liquid crystal screen to be tested; if the If there are pixels in the displayed picture whose pixel luminance is lower than the second-level luminance, the second indicator light indicates that there is a normally dark defect in the liquid crystal screen to be tested.

A normal indication module 4214, configured to pass The third indicator light indicates that there is no defect in the liquid crystal screen to be tested.

The test data transmission module 4215 is used to transmit the test data to the server of the liquid crystal screen production system through the serial port 423 .

Wherein, the test data includes the test result of whether the liquid crystal screen to be tested has defects; Often dark defect.

All operations of the main chip 421 are controlled by the main chip control module 422 .

In summary, the liquid crystal screen defect detection system provided by the embodiment of the present invention inputs a preset picture to the liquid crystal screen to be tested, uses an image acquisition device to collect the actual picture displayed on the liquid crystal screen to be tested, and collects the actual The picture is transmitted to the test board. The main chip of the test board has the function of automatically obtaining the pixel brightness of each pixel in the actual picture. The main chip of the test board compares the pixel brightness of each pixel in the actual picture with the preset first-order brightness. Compare, or compare the pixel brightness of each pixel in the actual picture with the preset second-level brightness, if there are pixels in the actual picture whose pixel brightness is greater than the first-level brightness, or there are pixels whose brightness is lower than the second-level brightness pixel, the main chip of the test board determines that there is a defect in the LCD screen to be tested, and indicates it through the indicator light. The entire detection process does not require manual participation, which improves the efficiency and reliability of detection, and avoids the problem of missed detection.

The system embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in One place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without any creative effort.

Through the above description of the implementations, those skilled in the art can clearly understand that each implementation can be implemented by means of software plus a necessary general hardware platform, and of course also by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in computer-readable storage media, such as ROM/RAM, magnetic discs, optical discs, etc., including several instructions to make a computer device (which may be a personal computer, server, or network device, etc.) execute the methods described in various embodiments or some parts of the embodiments.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (10)

1. A detection method for liquid crystal screen defect, is characterized in that, comprises: The main chip of the test board receives the picture displayed by the liquid crystal screen to be tested from the image acquisition device; screen; The main chip of the test board judges whether there are pixels whose pixel brightness is higher than the first-order brightness in the displayed picture, or whether there are pixels whose pixel brightness is lower than the second-order brightness in the displayed picture, and the The first-level brightness is greater than the second-level brightness; If it exists, the main chip of the test board indicates that the liquid crystal screen to be tested has a defect through an indicator light. 2. The method according to claim 1, wherein the preset picture is a pure black picture or a pure white picture; When the preset picture is a pure black picture, the main chip of the test board judges whether there are pixels whose pixel brightness is greater than the first order brightness in the displayed picture; When the preset picture is a pure white picture, the main chip of the test board judges whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed picture. 3. method according to claim 1, it is characterized in that, if exist, then the main chip of described test board indicates that there is defect in described liquid crystal screen to be tested by indicator light, comprising: If there is a pixel point with a pixel brightness greater than the first-order brightness in the displayed picture, the main chip of the test board indicates that there is a constant bright defect in the liquid crystal screen to be tested through the first indicator light; If there are pixels with pixel brightness lower than the second-level brightness in the displayed picture, the main chip of the test board indicates that the liquid crystal screen to be tested has a normally dark defect through the second indicator light. 4. The method according to claim 1, further comprising: If there is no pixel point with a pixel brightness greater than the first level brightness in the displayed picture, and there is no pixel point with a pixel brightness lower than the second level brightness in the displayed picture, then the main chip of the test board passes The third indicator light indicates that there is no defect in the liquid crystal screen to be tested. 5. method according to claim 3, it is characterized in that, the main chip of described test board transmits test data to the server of liquid crystal screen production system by the serial port that is provided with on described test board; Wherein, the test data includes the test result of whether the liquid crystal screen to be tested has defects; Often dark defect. 6. A detection system for liquid crystal screen defects, characterized in that it comprises: An image acquisition device, which is used to collect the actual picture displayed by the liquid crystal screen to be tested after inputting a preset picture to the liquid crystal screen to be tested; The test board includes a main chip, and the main chip includes: The picture receiving module is used to receive the actual picture displayed on the liquid crystal screen to be tested from the image acquisition device; A pixel judging module, configured to judge whether there are pixels whose pixel brightness is greater than the first-level brightness in the displayed actual picture, or whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture, The first-level brightness is greater than the second-level brightness; A defect indication module, configured to pass an indication if there are pixels whose pixel brightness is greater than the first-level brightness in the displayed actual picture, or, if there are pixels whose pixel brightness is lower than the second-level brightness in the displayed actual picture. The light indicates that the LCD screen under test is defective. 7. The system according to claim 6, wherein the preset picture is a pure black picture or a pure white picture; When the preset picture is a pure black picture, the pixel judging module is used to judge whether there are pixels with pixel brightness greater than the first-level brightness in the displayed picture; When the preset picture is a pure white picture, the pixel judging module is used to judge whether there are pixels whose pixel brightness is lower than the second-level brightness in the displayed picture. 8. The system of claim 6, wherein: If there is a pixel point with a pixel brightness greater than the first-order brightness in the displayed picture, the defect indication module indicates that there is a constant bright defect in the liquid crystal screen to be tested through the first indicator light; If there is a pixel point whose pixel brightness is lower than the second-level brightness, the second indicator light indicates that there is a normally dark defect in the liquid crystal screen to be tested. 9. The system according to claim 6, wherein the main chip further comprises: The normal indication module is used to: if there is no pixel point whose pixel brightness is higher than the first level brightness in the displayed picture, and there is no pixel point whose pixel brightness is lower than the second level brightness in the displayed picture, then pass the second level Three indicator lights indicate that there is no defect in the LCD screen to be tested. 10. The system according to claim 8, wherein the test board is provided with a serial port, and the main chip also includes: The test data transmission module is used to transmit the test data to the server of the liquid crystal screen production system through the serial port; Wherein, the test data includes the test result of whether the liquid crystal screen to be tested has defects; Often dark defect.