WO2023023900A1

WO2023023900A1 - Backplane detection system and detection method therefor

Info

Publication number: WO2023023900A1
Application number: PCT/CN2021/114122
Authority: WO
Inventors: 蒋光平; 林浩翔; 蔡明达
Original assignee: 重庆康佳光电技术研究院有限公司
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2023-03-02

Abstract

A backplane detection system for an LED display backplane (2) and a detection method therefor. The backplane detection system comprises a polarizing assembly (10), a liquid crystal apparatus (30) located in the middle of the polarizing assembly (10), an image collection apparatus (40) located on the side of the polarizing assembly (10) away from the LED display backplane (2), and a signal loading apparatus (50), wherein the polarizing assembly (10) comprises a first polarizing member (11) and a second polarizing member (12) which have polarization axes perpendicular to each other and are respectively located on two opposite sides of the liquid crystal apparatus (30); the image collection apparatus (40) comprises a light source (41) for emitting light and an imaging device (42) for receiving reflected light and generating a feature image; and the signal loading apparatus (50) is used for applying an electric signal to the LED display backplane (2), such that a voltage difference that periodically changes is comprised between each pair of electrodes on the LED display backplane (2), thereby detecting in advance whether a defective electrode exists in the LED display backplane (2), preventing the defective electrode from being bonded onto an LED chip, and lowering the repairing difficulty of the LED display backplane (2).

Description

Backplane detection system and detection method thereof

technical field

The present application relates to the technical field of detection, in particular to a backplane detection system and detection method for LED display backplanes.

Background technique

Compared with the current LCD and OLED display devices, Micro-LED display devices have outstanding advantages such as fast response, wide color gamut, high PPI, and low energy consumption, so they have gradually developed into one of the hot spots of future display technology and tend to replace LCD and OLED display devices.

The Micro-LED display device is a product of multiple red, green and blue Micro-LED chips arranged according to certain rules and bonded to the LED display backplane. When any of the Micro-LED chips and the LED display backplane is defective All will affect the use of Micro-LED display devices. Among them, during the production process of the LED display backplane, there may be appearance defects such as surface scratches and surface pollution, and there may also be internal defects such as electrode short circuit or electrode open circuit, which will affect the use of Micro-LED display devices. Therefore, LED The detection of the display backplane is very important.

technical problem

At present, the detection of LED display backplane usually adopts the way of optical detection. Specifically, after bonding a good Micro-LED chip to the LED display backplane, apply an electrical signal to the LED display backplane and determine whether there is an electrode short circuit or electrode failure on the LED display backplane by photographing whether the Micro-LED chip is lit. Open circuit (i.e. bad electrode). However, although the above-mentioned optical inspection method can detect defective electrodes on the LED display backplane, these defective electrodes have been bonded to Micro-LED chips, which greatly increases the difficulty of repairing the LED display backplane.

technical solution

In order to solve the above technical problems, this application proposes a backplane detection system and its detection method, which can detect in advance whether there are bad electrodes on the LED display backplane when used to detect the LED display backplane, so as to avoid the bad electrodes from being connected to the LED display. Chip bonding reduces the difficulty of repair.

In order to achieve the above object, on the one hand, the present application provides a backplane detection system for detecting an LED display backplane, where multiple pairs of electrodes are arranged in an array on one side of the LED display backplane, and the backplane detection system includes:

A polarizing assembly, including a first polarizer located on one side of the LED display backplane and a second polarizer located on a side of the first polarizer away from the LED display backplane, the first polarizer The polarization axis is perpendicular to the polarization axis of the second polarizer;

a liquid crystal device located between the first polarizer and the second polarizer, the liquid crystal device comprising a liquid crystal layer covering at least the plurality of pairs of electrodes on the LED display backplane;

An image acquisition device, located on the side of the second polarizer away from the liquid crystal device, the image acquisition device includes a light source and an imaging device, the light source is used to emit light, and the imaging device is used to receive reflected light and generate feature image; and

A signal loading device, the signal loading device is used for applying an electrical signal to the LED display backplane, so that there is a voltage difference between each pair of electrodes on the LED display backplane that changes periodically.

On the other hand, the present application also provides a backplane detection method, which uses the above-mentioned backplane detection system to detect the LED display backplane, and the backplane detection method includes:

The signal loading device is electrically connected to the LED display backplane, and an electrical signal is applied to the LED display backplane through the signal loading device, so that there is a gap between each pair of electrodes on the LED display backplane. A voltage difference that changes periodically;

The light source in the image acquisition device emits light to the LED display backplane, and the imaging device in the image acquisition device receives the reflected light reflected by the LED display backplane and sequentially transmitted through the polarizing component and the liquid crystal device, the imaging device generates a characteristic image; and

Judging whether each electrode of the LED display backplane is good or not according to the feature image.

Beneficial effect

In the backplane detection system and detection method thereof provided in the present application, the electrical signal is applied to the LED display backplane through the signal loading device, so that each pair of electrodes of the LED display backplane has a periodically changing The voltage difference can form between each pair of electrodes a transverse electric field whose electric field size also changes periodically, thus, under the action of the transverse electric field, the deflection angle of the liquid crystal molecules in the liquid crystal layer is also Periodic changes, so that the total amount of incident light passing through the polarizing assembly and the liquid crystal device and irradiating on the LED display backplane can be periodically adjusted, so that the imaging device receives the LED display backplane The reflected light corresponding to generates the characteristic image showing a plurality of flickering dots. By observing the display screen of the characteristic image, it can be judged whether each of the electrodes of the LED display backplane is good, so as to detect in advance whether there is a bad electrode in the LED display backplane, and avoid the bad electrode from colliding with the LED chip. Bonding reduces the difficulty of repairing the LED display backplane.

Description of drawings

FIG. 1 is a schematic diagram of a backplane detection system provided by an embodiment of the present application in a state where no electrical signal is applied to the LED display backplane.

FIG. 2 is a schematic diagram of the backplane detection system shown in FIG. 1 in a state where an electrical signal is applied to the LED display backplane.

FIG. 3 is a schematic diagram of a transverse electric field generated when an electrical signal is applied to a pair of electrodes on the LED display backplane shown in FIG. 2 .

FIG. 4 is a graph showing the relationship between deflection angles of liquid crystal molecules in the liquid crystal layer shown in FIG. 2 and external voltages.

FIG. 5 is a schematic diagram of a curve showing that the voltage difference between each pair of electrodes on the LED display backplane shown in FIG. 2 changes periodically with time.

FIG. 6 is a schematic diagram of the light transmittance of the light-transmitting combination formed by the polarizing component and the liquid crystal device shown in FIG. 2 periodically changing with time.

FIG. 7 is a schematic flowchart of a backplane detection method provided by an embodiment of the present application.

Explanation of reference numerals: 1 - backplane detection system; 2 - LED display backplane; 10 - polarizer assembly; 11 - first polarizer; 12 - second polarizer; 21 - first electrode; 22 - second electrode; 22'-bad electrode; 30-liquid crystal device; 31-liquid crystal layer; 40-image acquisition device; 41-light source; 42-imaging equipment; 50-signal loading device.

Embodiments of the present invention

In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Preferred embodiments of the application are shown in the accompanying drawings. However, the present application can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the description of the application is only for the purpose of describing specific embodiments, and is not intended to limit the application.

In the prior art, when testing the LED display backplane, it is necessary to bond all the electrodes on the LED display backplane to the LED chips first, and then detect whether there are bad electrodes on the LED display backplane by optical detection method, but these bad electrodes The electrode has been bonded to the Micro-LED chip, which will greatly increase the difficulty of repairing the LED display backplane.

Based on this, the present application hopes to provide a solution capable of solving the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

Please refer to FIG. 1 and FIG. 2 together. A backplane detection system 1 provided by an embodiment of the present application is used to detect whether there are defective electrodes in multiple pairs of electrodes on the LED display backplane 2 . Wherein, each pair of electrodes on the LED display backplane 2 includes a first electrode 21 and a second electrode 22 . It can be understood that, since the LED display backplane 2 has multiple manufacturing processes, there may be one or more bad electrodes on the LED display backplane 2, and the bad electrodes may be the first The electrode 21 may also be the second electrode 22 . For the convenience of description, as shown in FIG. 1 and FIG. 2 , the backplane detection system 1 is further described by taking the LED display backplane 2 including a defective electrode 22 ′ as an example.

As shown in FIG. 1 and FIG. 2 , the backplane inspection system 1 specifically includes a polarizer assembly 10 , a liquid crystal device 30 , an image acquisition device 40 and a signal loading device 50 . Wherein, the polarizer assembly 10 includes a first polarizer 11 located on one side of the LED display backplane 2 and a second polarizer located on a side of the first polarizer 11 away from the LED display backplane 2 12 , the polarization axis of the first polarizer 11 is perpendicular to the polarization axis of the second polarizer 12 . The liquid crystal device 30 is located between the first polarizer 11 and the second polarizer 12, and the liquid crystal device 30 includes a liquid crystal layer 31 covering at least the pairs of electrodes on the LED display backplane 2 . The image acquisition device 40 is located on the side of the second polarizer 12 away from the liquid crystal device 30, the image acquisition device 40 includes a light source 41 and an imaging device 42, the light source 41 is used to emit light, the imaging Device 42 is used to receive reflected light and generate a characteristic image. The signal loading device 50 is electrically connected to the LED display backplane 2, and the signal loading device 50 is used to apply an electrical signal to the LED display backplane 2, so that there is a periodic change between each pair of electrodes. The voltage difference to form a transverse electric field E (see FIG. 3 ) that deflects the liquid crystal molecules of the liquid crystal layer 31, so as to adjust the sequential transmission of the second polarizer 12, the liquid crystal device 30 and the first polarized light. 11 and irradiates the total amount of incident light on the LED display backplane 2 . It can be understood that the incident light is reflected by the LED display back panel 2 and then sequentially passes through the first polarizer 11, the liquid crystal device 30 and the second polarizer 12 to be captured by the imaging device. 42 receives and forms a characteristic image, and the characteristic image is used to judge whether each of the electrodes is good or not.

Those skilled in the art know that when light is irradiated on the polarizer assembly 10, the first polarizer 11 is used to transmit linearly polarized light polarized along the first direction, and the second polarizer 12 is used to Transmitting linearly polarized light polarized along the second direction, wherein the first direction is perpendicular to the second direction; the liquid crystal molecules in the liquid crystal layer 31 will be deflected under the action of an external electric field, and their optical properties will be corresponding Change, the light will undergo birefringence when passing through the liquid crystal layer 31, thereby changing the polarization direction of the light passing through the liquid crystal layer 31, and the change angle of the polarization direction of the light is related to the deflection angle of the liquid crystal layer 31 same. Combining the light filtering effect of the polarizing component 10 and the optical rotation effect of the liquid crystal layer 31 with or without an external electric field, the imaging device 42 can form different images.

Specifically, as shown in FIG. 1, when no electrical signal is applied to the LED display backplane 2, there is no voltage difference between the first electrode 21 and the second electrode 22 of each pair of electrodes, and each pair of electrodes No transverse electric field E is formed between them, and the liquid crystal molecules in the liquid crystal layer 31 do not deflect, so that the polarization direction of the light passing through the liquid crystal layer 31 will not be changed, so that the light from the light source 41 passes through the first The polarization direction after the second polarizer 12 does not change, but directly passes through the liquid crystal layer 31 of the liquid crystal device 30 , and finally reaches the first polarizer 11 . Because the polarization axis of the second polarizer 12 is perpendicular to the polarization axis of the first polarizer 11, the polarization direction of the light passing through the liquid crystal layer 31 is also the same as the polarization axis of the first polarizer 11. vertical, so that all the light passing through the liquid crystal layer 31 is absorbed by the first polarizer 11, so that no light can be irradiated on the LED display backplane 2 and reflected to the imaging device 42, so the imaging Device 42 displays a black image.

As shown in Figure 2 and Figure 3, when the LED display backplane 2 is applied with an electrical signal, there is a voltage difference between the first electrode 21 and the second electrode 22 of each pair of electrodes, and the voltage difference between each pair of electrodes is A transverse electric field E is formed between them, so that the liquid crystal molecules in the liquid crystal layer 31 are deflected, and the polarization direction of the light passing through the liquid crystal layer 31 is changed, so that the light from the light source 41 passes through the second polarizer 12 and the polarization direction after the liquid crystal layer 31 changes, and finally reaches the first polarizer 11 . Because the polarization direction of the light passing through the liquid crystal layer 31 changes, that is, the polarization direction of the light will not be perpendicular to the polarization axis of the first polarizer 11, so the light passing through the second polarizer 12 and the The polarization direction of at least part of the light components of the light from the liquid crystal layer 31 is parallel to the polarization axis of the first polarizer 11, so that this part of the light components can pass through the first polarizer 11 and irradiate on the LED display. on the back plate 2, and is reflected to the imaging device 42, so that the imaging device 42 can form a characteristic image.

Among them, those skilled in the art know that, within a reasonable range, when the voltage difference between each pair of electrodes is larger, the electric field of the transverse electric field E formed between each pair of electrodes The larger the value, the larger the deflection angle of the liquid crystal molecules in the liquid crystal layer 31, and the larger the polarization angle changed by the liquid crystal layer 31 after the light from the light source 41 passes through the second polarizer 12. big. It can be understood that the larger the polarization angle of the light passing through the second polarizer 12 is changed by the liquid crystal layer 31, the more polarized the light finally reaches the first polarizer 11. tends to be parallel to the polarization axis of the first polarizer 11, so the more light components that reach the first polarizer 11 are parallel to the polarization axis of the first polarizer 11, and thus pass through the first polarizer 11 The more the incident light irradiates the first polarizer 11 and irradiates the LED display backplane 2, the more the incident light is reflected by the LED display backplane 2 to the imaging device 42. more, so that the brightness of the characteristic image formed by the imaging device 42 is greater.

In the embodiment of the present application, the voltage difference between each pair of electrodes changes periodically, so that the electric field magnitude of the transverse electric field E also changes periodically, so that the light passing through the second polarizer 12 The polarization angle of the light whose polarization direction is changed by the liquid crystal layer 31 also changes periodically, thus, the total amount of light irradiated on the LED display backplane 2 and reflected to the imaging device 42 changes periodically, The brightness of the characteristic image formed by the imaging device 42 is made to flicker.

In addition, it can also be understood that, in the embodiment of the present application, when there is a defective electrode 22' in the LED display backplane 2, the lateral electric field cannot be formed between the defective electrode 22' and the corresponding first electrode 21. E, but the first electrode 21 can form a transverse electric field E between the other second electrode 22 on the side away from the bad electrode 22 ′, so the liquid crystal layer 31 covers the bad electrode correspondingly 22' will not be deflected, but the liquid crystal molecules covered by the liquid crystal layer 31 and the first electrode 21 corresponding to the defective electrode 22' will be deflected. The light on the part of the first polarizer 11 corresponding to the defective electrode 22' will be absorbed by the first polarizer 11, so that the defective electrode 22' on the LED display backplane 2 does not reflect light, And other good electrodes can reflect light, and then make described bad electrode 22 ′ appear as black dot image in the feature image correspondingly formed by described imaging device 42, while other good electrodes are formed in correspondingly formed image of described imaging device 42 A flickering dot image in the feature image.

To sum up, in the backplane detection system 1 provided in this application, an electrical signal is applied to the LED display backplane 2 through the signal loading device 50, so that each pair of electrodes of the LED display backplane 2 There is a voltage difference between them that changes periodically, so that a transverse electric field E that also changes periodically in the electric field can be formed between each pair of electrodes, thus, under the action of the transverse electric field E, the liquid crystal The deflection angle of the liquid crystal molecules in the layer 31 also changes periodically, so that the total amount of incident light passing through the polarizer assembly 10 and the liquid crystal device 30 and irradiating on the LED display backplane 2 can be periodically adjusted, The imaging device 42 is able to receive the reflected light of the LED display backplane 2 and correspondingly generate a characteristic image displaying a plurality of flickering points (each flickering point corresponds to a good electrode). By observing the display screen of the characteristic image, it can be judged whether each electrode of the LED display backplane 2 is good, so as to detect in advance whether there are defective electrodes in the LED display backplane 2 . Compared with the optical detection method in the prior art to detect whether there are bad electrodes on the LED display backplane, when the backplane detection system 1 provided by the application is used for the detection of the LED display backplane 2, it can Before the LED display backplane 2 is bonded to the LED chip, it is detected whether there is a defective electrode in the LED display backplane 2, thereby avoiding the bonding of the defective electrode and the corresponding LED chip, and reducing the Difficulty of late restoration.

Wherein, it should be noted that, in the embodiment of the present application, the LED display backplane 2 may be a Mini-LED display backplane or a Micro-LED display backplane, which is not limited.

Furthermore, in the embodiment of the present application, the polarizer assembly 10 and the liquid crystal device 30 can be arranged on the side close to the LED display backplane 2 where the pairs of electrodes are provided, or they can be arranged on the side far away from the LED display backplane 2. The side of the LED display backplane 2 provided with the plurality of pairs of electrodes is preferably located near the side of the LED display backplane 2 provided with the plurality of pairs of electrodes, so that the liquid crystal layer 31 and the LED display backplane The distance between the plurality of pairs of electrodes on the plate 2 is small, which means that the voltage difference between each pair of electrodes does not need to be very large, so that an electric field can be formed between each pair of electrodes. The transverse electric field E of the liquid crystal layer 31 deflects the liquid crystal molecules, thus, the signal application device 50 does not need to apply an electrical signal with a large voltage value (that is, the output power is small), which is beneficial to energy saving , and can improve the service life of the signal loading device 50 .

In addition, in the embodiment of the present application, the liquid crystal device 30 may be an IPS liquid crystal device or an FFS liquid crystal device that utilizes a transverse electric field to achieve optical rotation, preferably an IPS liquid crystal device; the light source 41 may be an LED point light source, or a The CCFL line light source can also be a surface light source composed of an LED point light source or a CCFL line light source combined with a light guide plate, which is not limited; the imaging device 42 can be a CCD camera or a TFT flat panel detector, preferably a CCD camera.

As mentioned above, under the action of the transverse electric field E formed between each pair of electrodes, the liquid crystal molecules in the liquid crystal layer 31 can be deflected, and the deflection angle of the liquid crystal molecules is related to the electric field of the transverse electric field E The magnitude is proportional, and the magnitude of the electric field of the transverse electric field E is proportional to the magnitude of the voltage difference between each pair of electrodes. Therefore, the deflection angle of the liquid crystal molecules in the liquid crystal layer 31 is proportional to the voltage The magnitude of the difference is proportional.

Specifically, referring to FIG. 4 , those skilled in the art know that when the external voltage of the liquid crystal layer 31 (that is, equivalent to the voltage difference between each pair of electrodes) gradually increases from zero, the The deflection angle of the liquid crystal molecules in the liquid crystal layer 31 also increases gradually. Wherein, as shown in FIG. 4 , during the process of the external voltage increasing from zero to the first voltage threshold V1, the liquid crystal molecules in the liquid crystal layer 31 hardly deflect or the deflection angle is extremely small; when the external voltage increases from When the first voltage threshold V1 increases to the second voltage threshold V2, the deflection angle of the liquid crystal molecules in the liquid crystal layer 31 starts to increase until they are fully deflected by 90 degrees; and when the external voltage changes from the second voltage threshold to When V2 continues to increase, the liquid crystal molecules in the liquid crystal layer 31 keep deflecting by 90 degrees. That is, when the voltage value of the external voltage of the liquid crystal layer 31 exceeds the first voltage threshold value V1, the liquid crystal molecules of the liquid crystal layer 31 start to deflect, and when the voltage value of the external voltage exceeds the first voltage threshold value V1 When V1 increases to the second voltage threshold V2, it is completely deflected by 90 degrees, and does not change following the increase of the external voltage. It can be understood that, when the types or molecular properties of the liquid crystal layer 31 are different, the corresponding first voltage threshold V1 and completely The corresponding second voltage threshold V2 during deflection will be different, which is not limited. Exemplarily, in an embodiment of the present application, the first voltage threshold V1 is 1V, and the second voltage threshold V2 is 2V.

Further, as mentioned above, the larger the deflection angle of the liquid crystal molecules in the liquid crystal layer 31 is, the larger the polarization angle of the light passing through the second polarizer 12 will be changed by the liquid crystal layer 31, so that the light that reaches The light on the first polarizer 11 has more light components parallel to the polarization axis of the first polarizer 11 , so that the light that passes through the first polarizer 11 and irradiates on the LED display backplane 2 The more incident light, that is, the total amount of incident light is proportional to the deflection angle of the liquid crystal molecules, and the deflection angle of the liquid crystal molecules is proportional to the voltage difference between each pair of electrodes . It can be seen that within a reasonable value range, the deflection angle of the liquid crystal molecules of the liquid crystal layer 31 and the total amount of the incident light are proportional to the magnitude of the voltage difference.

Preferably, in an embodiment of the present application, the value range of the voltage difference is set to be greater than or equal to the first voltage threshold V1 and less than or equal to the voltage range of the second voltage threshold V2. It can be understood that the electrical signal applied to the LED display backplane 2 is controlled by the signal loading device 50, so that the voltage difference formed between each pair of electrodes changes within the appropriate range, That is, the deflection angle of the liquid crystal molecules in the liquid crystal layer 31 can be controlled to vary within the range of 0° to 90°, so that the total amount of the incident light also has a large variation range, so that each good The flickering points corresponding to the electrodes in the characteristic image have relatively large brightness changes, which is convenient for observers to observe, thereby improving the accuracy of detection.

Please refer to FIG. 2 and FIG. 3 again. In the embodiment of the present application, when the electrical signal is applied to the LED display backplane 2 through the signal loading device 50, the electrical signal includes applying to each of the first electrodes 21 The first electrical signal and the second electrical signal applied to each of the second electrodes 22 . Wherein, the first electrical signal and the second electrical signal may both be electrical signals with a positive voltage value, or both may be electrical signals with a negative voltage value, or one of them may be an electrical signal with a positive voltage value. signal, and the other is an electrical signal with a negative voltage value, as long as the voltage value of the first electrical signal is greater than the voltage value of the second electrical signal to form the voltage difference between each pair of electrodes . Specifically, as shown in FIG. 2 and FIG. 3 , in an embodiment of the present application, the first electrical signal is an electrical signal with a positive voltage value (such as any value from 0.5V to 1V), and the first electrical signal The second electrical signal is an electrical signal with a negative voltage value (for example, any value from -1V to -0.5V).

In the embodiment of the present application, by adjusting the signal applying device 50 to provide any one of the above-mentioned electrical signal combinations, so as to apply electrical signals with different voltage values to different electrodes in each pair of electrodes, that is, each pair The voltage difference is formed between the electrodes, and the matching schemes of electrical signal combinations are various, which is beneficial to improve the flexibility of use of the signal loading device 50 .

Wherein, the signal loading device 50 may be a combination of an output device and an adjustment device, the output device is used to output the first electrical signal and the second electrical signal, and the adjustment device is used to adjust the first electrical signal electrical signal and the second electrical signal; the signal loading device 50 can also be a combination of the first loading device and the second loading device, the first loading device is used to output and adjust the first electrical signal, the first loading device The second signal loading device is used to output and adjust the second electrical signal; of course, the signal loading device 50 can also be a combination of devices in other forms, as long as it can output different first electrical signals and second electrical signals correspondingly That is, there is no limitation on this.

Further, please refer to FIG. 5. Optionally, in an embodiment of the present application, by adjusting the respective voltage values of the first electrical signal and the second electrical signal through the signal loading device 50, the The voltage value of the voltage difference first increases and then decreases and changes periodically. Specifically, as shown in FIG. 5 , in an embodiment of the present application, the change curve of the voltage difference is a sawtooth curve; within the time period of 0-t, the voltage difference between each pair of electrodes It gradually increases from zero, and then in each cycle T after time t, the voltage difference first increases linearly and then decreases linearly.

Wherein, in each change period T, the voltage difference between each pair of electrodes first increases linearly and then decreases linearly, which can be realized through various implementation manners. For example, in one implementation manner, the voltage value of the second electrical signal remains unchanged, and the voltage value of the first electrical signal increases linearly and then decreases linearly in each period T; another implementation manner , the voltage value of the first electrical signal remains unchanged, and the voltage value of the second electrical signal decreases linearly and then increases linearly in each period T; in yet another implementation manner, the first Both the voltage value of the electrical signal and the voltage value of the second electrical signal can increase linearly and then decrease linearly in each period T, but the increment or decrement of the first electrical signal is larger than the second electrical signal. The increment or decrement corresponding to the electrical signal; of course, the voltage difference first linearly increases and then linearly decreases can also be realized through other implementation manners, which will not be described in detail.

In other embodiments, the respective voltage values of the first electrical signal and the second electrical signal are adjusted by the signal loading device 50, and the voltage value of the voltage difference first increases and then decreases and is periodic When changing, the variation curve of the voltage difference may also be a cosine wave curve.

In other embodiments, by adjusting the respective voltage values of the first electrical signal and the second electrical signal through the signal loading device 50, the voltage value of the voltage difference can also be between the high voltage value and the low voltage value. The values change periodically and alternately, and the change curve corresponding to the voltage difference is a pulse curve in which the high voltage value and the low voltage value are alternately switched.

In the embodiment of the present application, after adjusting the signal loading device 50 to provide any one of the aforementioned electrical signal combinations to form a voltage difference between each pair of electrodes, the signal loading device 50 can be further adjusted to change The voltage values of different electrical signals enable the voltage difference formed between each pair of electrodes to have any of the above-mentioned voltage images, which is beneficial to further improving the flexibility of use of the signal loading device 50 .

It should be noted that, as shown in FIG. 5 , in each period T, the voltage difference has a minimum value Vmin and a maximum value Vmax. In the embodiment of the present application, all the voltage differences between each pair of electrodes The minimum value Vmin of the voltage difference is not less than the aforementioned first voltage threshold V1, so as to ensure that the voltage difference in each period T can deflect the liquid crystal molecules in the liquid crystal layer 31, and the voltage difference The maximum value Vmax is not greater than the second voltage threshold V2, so as to ensure that the deflection angle of the liquid crystal molecules in the liquid crystal layer 31 can also be continuously changed when the voltage difference in each period T is continuously changed. Preferably, in an embodiment of the present application, the minimum value Vmin of the voltage difference is equal to the first voltage threshold V1 (1V) corresponding to when the liquid crystal molecules of the liquid crystal layer 31 start to deflect, and the maximum value of the voltage difference is The value Vmax is equal to the second voltage threshold V2 (2V) corresponding to when the liquid crystal molecules of the liquid crystal layer 31 are completely deflected, so that in each period T, the liquid crystal molecules of the liquid crystal layer 31 continuously rotate between 0° and 90° Variety.

It should also be noted that, in order to ensure that the image corresponding to each electrode in the characteristic image can be observed by human eyes or machines, the change period T of the voltage difference should be greater than a temporary threshold, and the temporary The persistence threshold can be the persistence threshold of vision of the human eye, or the discrimination response threshold of the machine. By adjusting the signal loading device 50 to control the variation period T of the voltage difference formed between each pair of electrodes to be greater than the persistence threshold, it is beneficial to ensure that each electrode corresponds to the characteristic image in the characteristic image. The image of the electrode is recognized to prevent the image corresponding to the electrode from changing too fast to be recognized, thereby improving the accuracy of judging whether each electrode is good or not according to the characteristic image.

Specifically, in an embodiment of the present application, when using a machine with a discrimination reaction threshold of 0.01s to observe the characteristic image, the time t required for the voltage difference to increase to the first voltage threshold V1 can be set is 0.05s, and the change period T of the voltage difference can be set to 0.25s. In this embodiment, when an electrical signal is applied to the LED display backplane 2 through the signal application device 50 for 0.05s, a sufficiently large voltage difference can be formed between each pair of electrodes to make the liquid crystal layer 31 liquid crystal molecules start to deflect, and within every 0.25s, the liquid crystal molecules of the liquid crystal layer 31 complete a reciprocating deflection between 0° and 90°, correspondingly, the machine can observe: every good The dot image corresponding to the electrode in the characteristic image formed by the imaging device 42 starts to light up after 0.05s and completes a flash every 0.25s thereafter. That is to say, the setting of the time t and the period T will respectively affect the time when each good electrode corresponding to the point image in the characteristic image starts to light up and the time required to complete one blink. Of course, in other embodiments, the time t and the change period T can also be set to other reasonable times according to the actual needs of the subject (human or machine) observing the feature image. Generally, the persistence of vision threshold of the human eye It must be greater than the discriminant response threshold of the machine, which is not specifically limited.

Further, please refer to FIG. 2 again. In the embodiment of the present application, the light emitted by the light source 41 sequentially passes through the second polarizer 12 , the liquid crystal device 30 and the first polarizer 11 and then shines on the On the LED display backplane 2, the second polarizer 12, the first polarizer 11 (that is, the polarizer assembly 10) and the liquid crystal device 30 are regarded as a light-transmitting combination, and the irradiated The light on the LED display backplane 2 is the transmitted light of the light-transmissive combination.

Wherein, as mentioned above, the second polarizer 12 and the first polarizer 11 are respectively used to filter and transmit linearly polarized light polarized in different directions, and the liquid crystal layer 31 of the liquid crystal device 30 is used to deflect the The polarization angle of the linearly polarized light transmitted by the second polarizer 12 is used to change the polarization direction of the light reaching the first polarizer 11 , so as to adjust the amount of transmitted light of the light-transmitting combination. It can be understood that, the optical characteristics of the polarizing assembly 10 remain unchanged, but the deflection angle of the liquid crystal molecules of the liquid crystal layer 31 changes with the change of the voltage difference between each pair of electrodes that changes periodically Therefore, the light transmittance of the light-transmitting combination is directly proportional to the voltage difference that changes periodically, so the light transmittance of the light-transmitting combination also changes periodically.

Specifically, please refer to FIG. 5 , in an embodiment of the present application, the voltage difference first increases linearly and then decreases linearly in each period T; correspondingly, please refer to FIG. 6 , the The light transmittance also increases linearly and then decreases linearly in each period T.

Wherein, as shown in FIG. 6, during the time period of 0-t, the light transmittance of the light-transmitting combination is 0, and in each period T after t, the light transmittance of the light-transmitting combination The pass rate between 0 and the maximum transmittance Smax shows a periodic change that first increases linearly and then decreases linearly.

This is because: as shown in FIG. 5 , within the time period of 0-t, the voltage value of the voltage difference is less than the minimum value Vmin. In an embodiment of the present application, the minimum value Vmin is the liquid crystal layer 31 corresponding to the aforementioned first voltage threshold V1 when the liquid crystal molecules start to deflect, so before the time t, the liquid crystal molecules in the liquid crystal layer 31 are not deflected, and the polarization direction of the light transmitted by the second polarizer 12 is not in the When passing through the liquid crystal device 30, it is unchanged and perpendicular to the polarization axis of the first polarizer 11, so that all the light that reaches the first polarizer 11 is absorbed by the first polarizer 11, so that no light Through the first polarizer 11 , that is, no light passes through the light-transmitting combination. Further, as shown in FIG. 5, after time t, the voltage difference changes periodically between the minimum value Vmin and a maximum value Vmax. In an embodiment of the present application, the maximum value Vmax That is, the aforementioned second voltage threshold V2 corresponding to when the liquid crystal molecules of the liquid crystal layer 31 are completely deflected (that is, deflected by 90 degrees), so that the liquid crystal molecules of the liquid crystal layer 31 are between 0 degrees and 90 degrees in each period T deflection, so that the polarization direction of the light transmitted by the second polarizer 12 also changes between 0 degrees and 90 degrees, that is, when it is parallel to the polarization axis of the first polarizer 11 and perpendicular to the first polarizer The polarization axes of the polarizer 11 vary; when the polarization direction of the light transmitted by the second polarizer 12 is parallel to the polarization axis of the first polarizer 11, the light that reaches the first polarizer 11 Through the first polarizer 11, the light transmittance of the light-transmitting combination at this time is the maximum value Smax; when the polarization direction of the light transmitted by the second polarizer 12 is perpendicular to the first polarizer When the polarization axis is 11, the light that reaches the first polarizer 11 is completely absorbed by the first polarizer 11, and at this time, the light transmittance of the light-transmitting combination is 0.

It can be understood that, among the light emitted by the light source 41, only part of the light whose polarization direction is parallel to the polarization axis of the second polarizer 12 passes through the second polarizer 12 and finally passes through the liquid crystal device 30 And the first polarizer 11 is irradiated on the LED display backplane 2 , so the maximum value Smax of the light transmittance of the light-transmitting combination is also less than 100% (see FIG. 6 ).

It can also be understood that, in another embodiment, when the change curve corresponding to the voltage difference is a cosine wave curve in which the voltage value increases first and then decreases and changes periodically, the light transmittance of the light-transmitting combination The curve corresponding to the overrate is also a cosine curve that first increases and then decreases and changes periodically; and in another embodiment, the change curve corresponding to the voltage difference is alternately switched between high voltage value and low voltage value As for the pulse curve, the curve corresponding to the light transmittance of the light-transmitting combination is also a pulse curve in which high transmittance and low transmittance are switched alternately, which will not be described in detail.

Please refer to FIG. 1 again. Optionally, in the embodiment of the present application, the first polarizer 11 may be a first polarizer, and the first polarizer is located at the liquid crystal device 30 close to the LED display backplane. 2, or the first polarizer 11 may be a first polarizing film, and the first polarizing film is attached to the side of the liquid crystal device 30 close to the LED display backplane 2.

Similarly, the second polarizer 12 can be a second polarizer, and the second polarizer is located on the side of the liquid crystal device 30 away from the LED display backplane 2, or the second polarizer 12 is a second polarizing film, and the second polarizing film is pasted on the side of the liquid crystal device 30 away from the LED display backplane 2 .

In the embodiment of the present application, both the first polarizer 11 and the second polarizer 12 can be polarizers or polarizing films, and are correspondingly arranged on opposite sides of the liquid crystal device 30, and the first polarizer The member 11 and the second polarizer 12 adopt any combination of polarizers and polarizer films, so that the polarizer assembly 10 can have various combinations, which improves the diversity of the backplane detection system 1 .

Preferably, in an embodiment of the present application, the liquid crystal device 30 may further include alignment components (not shown in FIG. 1 and FIG. The first alignment layer between the first polarizer 11 and the liquid crystal layer 31 and the second alignment layer between the second polarizer 12 and the liquid crystal layer 31 . By respectively setting an alignment layer on opposite sides of the liquid crystal layer 31, all the liquid crystal molecules in the liquid crystal layer 31 have the same initial alignment direction, preferably, the long axis directions of all liquid crystal molecules are parallel to The extension direction of the polarizing axis of the first polarizer 11 (see FIG. 1 ) enables all the liquid crystal molecules to be aligned by the same angle under the action of the transverse electric field E, which is beneficial to improve the liquid crystal device 30. Uniformity of transmitted light.

Preferably, in an embodiment of the present application, the liquid crystal device 30 further includes a transparent conductive layer (not shown in FIG. 1 and FIG. 2 ) located between the liquid crystal layer 31 and the second polarizer 12 , for To shield the electrical signal on the side of the liquid crystal layer 31 away from the LED display backplane 2 . The transparent conductive layer is provided on the side of the liquid crystal layer 31 away from the LED display backplane 2, which will not affect the light transmittance of the liquid crystal layer 31, and can also shield the electrical signal generated by the image acquisition device 40. , so as to avoid the electrical signal from interfering with the liquid crystal molecules of the liquid crystal layer 31 .

Optionally, in an embodiment of the present application, the backplane detection system 1 further includes a stage, which is used to carry the LED display backplane 2, and is also used to separate the LED display backplane 2 through some fixing components. The polarizer assembly 10 , the liquid crystal device 30 , the image acquisition device 40 and the signal loading device 50 are fixed on the stage.

Please refer to FIG. 7 , the present application also provides a backplane detection method, which uses the backplane detection system 1 in any of the above-mentioned embodiments to detect the LED display backplane 2 . Specifically, please refer to FIG. 1 to FIG. 3 and FIG. 7 together. The backplane detection method includes the following steps:

Step S1, electrically connecting the signal loading device 50 to the LED display backplane 2, and applying an electrical signal to the LED display backplane 2 through the signal loading device 50, so that the LED display backplane 2 There is a periodic voltage difference between each pair of electrodes.

Step S2, emit light to the LED display backplane 2 through the light source 41 in the image acquisition device 40, and receive light reflected by the LED display backplane 2 through the imaging device 42 in the image acquisition device 40 and then transmit through the LED display backplane 2 sequentially. The imaging device 42 generates a characteristic image of the light reflected by the polarizer assembly 10 and the liquid crystal device 30 .

Step S3, judging whether each electrode of the LED display backplane 2 is good or not according to the feature image.

In the above-mentioned backplane detection method, an electrical signal is applied to the LED display backplane 2 through the signal loading device 50, so that each pair of electrodes of the LED display backplane 2 has a periodically changing voltage difference value, and then can form a transverse electric field E (see FIG. 3 ) in which the magnitude of the electric field also changes periodically between each pair of electrodes. Thus, under the action of the transverse electric field E, the liquid crystal in the liquid crystal layer 31 The deflection angle of the molecules also changes periodically, so that the total amount of incident light that passes through the polarizing assembly 10 and the liquid crystal device 30 and irradiates on the LED display backplane 2 can be periodically adjusted, so that the imaging The device 42 receives the reflected light from the LED display backplane 2 and correspondingly generates the characteristic image displaying a plurality of blinking points. By observing the display screen of the characteristic image, it can be judged whether each electrode of the LED display backplane 2 is good, so as to detect whether there is a bad electrode in the LED display backplane 2 in advance, and avoid the bad electrode from being associated with the electrode. LED chip bonding reduces the difficulty of repairing the LED display backplane 2 .

It can be understood that the imaging device 42 can form different images by combining the light filtering effect of the polarizing component 10 and the optical rotation effect of the liquid crystal layer 31 with or without an external electric field. Specifically, as shown in FIG. 1, when no electrical signal is applied to the LED display backplane 2, there is no voltage difference between the first electrode 21 and the second electrode 22 of each pair of electrodes, and each pair of electrodes No transverse electric field E is formed between them, and the liquid crystal molecules in the liquid crystal layer 31 do not deflect, so that the polarization direction of the light passing through the liquid crystal layer 31 will not be changed, so that the light from the light source 41 passes through the first The polarization direction after the second polarizer 12 does not change, but directly passes through the liquid crystal layer 31 of the liquid crystal device 30 , and finally reaches the first polarizer 11 . Because the polarization axis of the second polarizer 12 is perpendicular to the polarization axis of the first polarizer 11, the polarization direction of the light passing through the liquid crystal layer 31 is also the same as the polarization axis of the first polarizer 11. vertical, so that all the light passing through the liquid crystal layer 31 is absorbed by the first polarizer 11, so that no light can be irradiated on the LED display backplane 2 and reflected to the imaging device 42, so the imaging Device 42 displays a black image.

In addition, it can also be understood that, as shown in FIG. 1 and FIG. 2 , in the embodiment of the present application, when there is a defective electrode 22 ′ in the LED display backplane 2 , the defective electrode 22 ′ and the corresponding first electrode The transverse electric field E cannot be formed between 21, but the transverse electric field E can be formed between the first electrode 21 and another second electrode 22 on the side away from the defective electrode 22', so the liquid crystal The liquid crystal molecules in the layer 31 correspondingly covering the defective electrode 22' will not be deflected, but the liquid crystal molecules covering the first electrode 21 corresponding to the defective electrode 22' in the liquid crystal layer 31 will be deflected, thus, only The light transmitted through the liquid crystal layer 31 and irradiated on the part of the first polarizer 11 corresponding to the defective electrode 22 ′ will be absorbed by the first polarizer 11 , so that the LED display backplane 2 The bad electrode 22' does not reflect light, while other good electrodes can reflect light, so that the bad electrode 22' appears as a black dot image in the corresponding characteristic image formed by the imaging device 42, while other good electrodes In the characteristic image correspondingly formed by the imaging device 42, there is a flickering dot image.

Therefore, in the backplane detection method provided in the present application, the step of judging whether each electrode of the LED display backplane 2 is good or not according to the characteristic image specifically includes:

When it is observed that the image corresponding to any of the electrodes in the characteristic image is a flashing dot image, it is determined that the electrode is good; and when it is observed that the image corresponding to any of the electrodes in the characteristic image is black When the dot image, determine that the electrode is bad.

In the backplane detection method provided by the present application, the good electrodes and bad electrodes on the LED display backplane 2 correspond to flickering dot images and black dot images respectively in the characteristic image, and the two correspond to distinct features. The different images are convenient for observation, which is beneficial to improve the accuracy of judging whether each electrode is good or not.

As shown in FIG. 1 and FIG. 2 , in the embodiment of the present application, each pair of electrodes on the LED display backplane 2 includes a first electrode 21 and a second electrode 22 . Optionally, in the backplane detection method provided in the present application, the signal loading device 50 is used to apply an electrical signal to the LED display backplane 2, so that each pair of LED display backplanes 2 The step of having a periodically changing voltage difference between the electrodes specifically includes:

In the first step, applying a first electrical signal to each of the first electrodes 21 through the signal loading device 50, and applying a second electrical signal to each of the second electrodes 22;

In the second step, the voltage values of the first electrical signal and the second electrical signal are adjusted by the signal loading device 50 so that the voltage value on the first electrode 21 is the same as the voltage on the second electrode 22 The difference in values varies periodically.

Further optionally, the applying the first electrical signal to each of the first electrodes 21 through the signal loading device 50, and applying the second electrical signal to each of the second electrodes 22 specifically includes:

Apply a first electrical signal to each of the first electrodes 21 through the signal loading device 50, so that the first electrodes 21 generate a first positive voltage value, and apply a second electrical signal to each of the second electrodes 22 , so that the second electrode 22 generates a second positive voltage value; or

Apply a first electrical signal to each of the first electrodes 21 through the signal loading device 50, so that the first electrodes 21 generate a first negative voltage value, and apply a second electrical signal to each of the second electrodes 22 , so that the second electrode 22 generates a second negative voltage value; or

Apply a first electrical signal to each of the first electrodes 21 through the signal loading device 50, so that the first electrodes 21 generate a positive voltage value, and apply a second electrical signal to each of the second electrodes 22, so that The second electrode 22 generates a positive voltage value.

In the backplane detection method provided in this application, the signal loading device 50 is adjusted to provide any of the above-mentioned electrical signal combinations, so as to display to the LED that different electrodes in each pair of electrodes of the backplane 2 are respectively Applying electrical signals with different voltage values can form the voltage difference between each pair of electrodes. The combination of different electrical signals has a variety of matching schemes, which is conducive to improving the flexibility of use of the signal loading device 50. It is also beneficial to improve the program diversity of the backplane detection method.

It can be understood that, in the backplane detection method provided in the present application, the polarizer assembly 10, the liquid crystal device 30, the image acquisition device 40, and the signal loading device 50 also have functions similar to the aforementioned backplane detection method. The structures and functions of the corresponding components in the system 1 are the same, and for more specific content, please refer to the related description above, which will not be repeated here.

It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes based on the above descriptions, and all these improvements and changes should belong to the protection scope of the appended claims of the present application.

Claims

A backplane detection system for detecting an LED display backplane, where multiple pairs of electrodes are arranged in an array on one side of the LED display backplane, wherein the backplane detection system includes:

A polarizing assembly, including a first polarizer located on one side of the LED display backplane and a second polarizer located on a side of the first polarizer away from the LED display backplane, the first polarizer The polarization axis is perpendicular to the polarization axis of the second polarizer;

a liquid crystal device located between the first polarizer and the second polarizer, the liquid crystal device comprising a liquid crystal layer covering at least the plurality of pairs of electrodes on the LED display backplane;

An image acquisition device, located on the side of the second polarizer away from the liquid crystal device, the image acquisition device includes a light source and an imaging device, the light source is used to emit light, and the imaging device is used to receive reflected light and generate feature image; and

A signal loading device, the signal loading device is used for applying an electrical signal to the LED display backplane, so that there is a voltage difference between each pair of electrodes on the LED display backplane that changes periodically.
The backplane detection system according to claim 1, wherein the first polarizer is a first polarizer, and the first polarizer is located on a side of the liquid crystal device close to the LED display backplane, Alternatively, the first polarizer is a first polarizing film, and the first polarizing film is attached to a side of the liquid crystal device close to the LED display backplane; and/or

The second polarizer is a second polarizer, and the second polarizer is located on the side of the liquid crystal device away from the LED display backplane, or the second polarizer is a second polarizer film, and the The second polarizing film is pasted on the side of the liquid crystal device away from the LED display backplane.
The backplane inspection system according to claim 1, wherein the liquid crystal device further comprises an alignment component, the alignment component includes a first alignment layer and a first alignment layer located between the first polarizer and the liquid crystal layer. A second alignment layer located between the second polarizer and the liquid crystal layer.
The backplane inspection system according to claim 1, wherein the liquid crystal device further comprises a transparent conductive layer located between the liquid crystal layer and the second polarizer for shielding the liquid crystal layer from the The LEDs show electrical signals on one side of the backplane.
A backplane detection method, said method uses the backplane detection system according to any one of claims 1 to 4 to detect the LED display backplane, characterized in that said backplane detection method comprises:

The signal loading device is electrically connected to the LED display backplane, and an electrical signal is applied to the LED display backplane through the signal loading device, so that there is a period between each pair of electrodes on the LED display backplane. Sexually changing voltage difference;

The light source in the image acquisition device emits light to the LED display backplane, and the imaging device in the image acquisition device receives the reflected light reflected by the LED display backplane and sequentially transmitted through the polarizing component and the liquid crystal device, the imaging device generates a characteristic image; and

Judging whether each electrode of the LED display backplane is good or not according to the feature image.
The backplane inspection method according to claim 5, wherein the step of judging whether each electrode of the LED display backplane is good or not according to the characteristic image specifically comprises:

When it is observed that the corresponding image of any one of the electrodes in the characteristic image is a flashing dot image, it is determined that the electrode is good; and

When it is observed that the image corresponding to any one of the electrodes in the characteristic image is a black dot image, it is determined that the electrode is defective.
The backplane detection method according to claim 5 or 6, wherein each pair of electrodes includes a first electrode and a second electrode, and the electrical signal is applied to the LED display backplane through the signal loading device. The step of making the LED display backplane have a periodically changing voltage difference between each pair of electrodes specifically includes:

applying a first electrical signal to each of the first electrodes through the signal loading device, and applying a second electrical signal to each of the second electrodes;

The voltage values of the first electrical signal and the second electrical signal are adjusted by the signal loading device, so that the difference between the voltage value on the first electrode and the voltage value on the second electrode is periodic Variety.
The backplane detection method according to claim 7, wherein the first electrical signal is applied to each of the first electrodes through the signal loading device, and the second electrical signal is applied to each of the second electrodes. Signals specifically include:

The first electrical signal is applied to each of the first electrodes through the signal loading device, so that the first electrode generates a first positive voltage value, and the second electrical signal is applied to each of the second electrodes, so that the the second electrode produces a second positive voltage value; or

The first electrical signal is applied to each of the first electrodes by the signal loading device, so that the first electrode generates a first negative voltage value, and the second electrical signal is applied to each of the second electrodes, so that the the second electrode generates a second negative voltage value; or

The first electrical signal is applied to each of the first electrodes by the signal loading device, so that the first electrode generates a positive voltage value, and the second electrical signal is applied to each of the second electrodes, so that the second The electrodes generate a negative voltage value.
The backplane detection method according to claim 5, wherein when the voltage difference is a first voltage threshold, the liquid crystal molecules in the liquid crystal layer start to deflect; when the voltage difference is a second voltage threshold, The liquid crystal molecules of the liquid crystal layer are deflected by 90 degrees;

A value of the voltage difference is greater than or equal to the first voltage threshold and less than or equal to the second voltage threshold.
The backplane detection method according to claim 9, characterized in that, the change cycle of the voltage difference is greater than the persistence threshold.