FPGA-based system for replacing OLED with LCD screen

Abstract

The invention is applied to the technical field of product communication, and discloses an FPGA (Field Programmable Gate Array)-based LCD (Liquid Crystal Display) screen replacement OLED (Organic Light Emitting Diode) system, which comprises an MIPI (Mobile Industry Processor Interface) decoding unit, an RAM (Random Access Memory) image cache unit, a clock recovery unit, a scaling interpolation unit, an output time sequence unit, an MIPI coding unit, a screen command unit and an ADC (Analog to Digital Converter) sampling unit, and the FPGA selected by the system is only Lattice-XO3. According to the FPGA-based system for replacing the OLED with the LCD screen, the problem that the resolution ratios of the LCD screen and the OLED screen are inconsistent is solved by adopting the scaling interpolation unit based on the RAM cache in the FPGA, high flexibility and adaptability are achieved, the system guarantees the quality and integrity of images through accurate interpolation calculation and scaling processing, the visual experience is improved, and the system is suitable for popularization and application. And the user can fully utilize the advantage of high resolution of the OLED screen after replacing the screen, and meanwhile, the problems of image deformation, blurring or incomplete display and the like possibly caused by mismatching of the resolution are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of product communication, and in particular to an FPGA-based LCD screen replacement OLED system. Background Art

[0002] In today's electronic product market, LCD (liquid crystal display) and OLED (organic light-emitting diode display) are the two most common display technologies. They are widely used in various devices such as televisions, computer monitors, mobile phones, tablets, etc. Although both are display technologies, they have significant differences in structure, performance and user experience. The working principle of LCD screen is based on the arrangement and twisting of liquid crystal molecules to control the passage of light. The liquid crystal molecules will change their arrangement under the action of a specific electric field, thereby controlling the degree of light penetration and displaying different colors and brightness. This technology requires a backlight layer to provide a light source, so the LCD screen is relatively thick in structure. The OLED screen uses a completely different working principle. It uses the self-luminous characteristics of organic materials. When current passes through, the organic material will directly emit light. This technology does not require a backlight layer, so the OLED screen can be thinner and lighter. In addition, since each pixel can independently control the light emission, the OLED screen can be almost completely non-luminous when displaying black, thereby achieving higher contrast and more Bright colors, OLED screens are gradually favored by the high-end market due to their excellent color performance and contrast. Although the manufacturing cost is relatively high, OLED screens are increasingly used in high-end TVs, mobile phones, tablets and other fields. With the advancement of technology and the increase in output, the price of OLED screens is gradually decreasing, and it is favored by more and more consumers. In daily work and life, it is common to accidentally break the screen, which also leads to the increasingly hot market for repaired screens. At the same time, as the performance of CPUs is getting better and better, the performance has gradually become surplus, so the demand for consumers to change their phones is also slowly slowing down, but the technology of screens is changing with each passing day. From the beginning of LCD screens to the current OLED / MINI-LED and flexible screens, people's continuous pursuit of display effects is reflected. However, the performance of previous electronic equipment still meets the use requirements, but the screen is an outdated product. To solve this problem, an FPGA-based LCD screen replacement OLED system is proposed to solve the problem that LCD devices cannot be upgraded by replacing OLED screens. Summary of the invention

[0003] The purpose of the present invention is to provide an FPGA-based LCD screen replacement OLED system to solve the problem that the LCD device mentioned in the above background technology cannot be upgraded by replacing the OLED screen.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an FPGA-based LCD screen replacement OLED system, comprising a MIPI decoding unit, a RAM image cache unit, a clock recovery unit, a scaling interpolation unit, an output timing unit, a MIPI encoding unit, a screen command unit and an ADC sampling unit. The FPGA selected for the system is only Lattice-XO3.

[0005] Preferably, the MIPI decoding unit is composed of two parts: video stream analysis and command handshake protocol;

[0006] The analysis of MIPI video stream first analyzes the LP state switching from LP11-LP01-LP00 to high-speed mode, then analyzes the packet header 00-00-00-00-00-B8 in the high-speed signal, and then analyzes the command packet SOT / EOT ​​to parse the video data stream signal;

[0007] The command handshake protocol detects the commands sent by the host, analyzes the commands that need to be answered, and performs handshake processing. If the host does not receive a response, it will enter a dormant state.

[0008] The above technical solution can accurately parse various signals in the MIPI video stream, ensure the correct extraction of video data, and provide an accurate data source for subsequent processing, so that the picture display is smooth and without lag, the video screen switches quickly in the game, and the scene transition is natural.

[0009] Preferably, the RAM image cache unit ensures the consistency of screen display specifications by scaling the screen display resolution.

[0010] The above technical solution effectively solves the problem of resolution scaling when screen specifications are inconsistent, ensures the normal display of images on different screens, and allows the game screen to be clearly presented on devices with different resolutions, avoiding image deformation or blurring, and improving the visual experience of the game.

[0011] Preferably, the clock recovery unit obtains all clocks of the internal processing unit after passing through the PLL based on the input MIPI-RX clock as a template, thereby preventing the data in the RAM from slowly shifting during the read-write process and eventually causing data overflow.

[0012] The above technical solution ensures the accuracy and stability of the internal processing clock, avoids data processing errors, and ensures stable image data transmission during game operation. It also prevents problems such as screen flickering or tearing due to clock deviation, thus ensuring the smoothness of the game.

[0013] Preferably, the points in the interpolation system of the scaling interpolation unit are bilinearly calculated by using four points obtained from the RAM cache, and the decimal part of the coordinates is the interpolation coefficient K, and the formula is as follows: K*X+(1-K)Y. Two pixels are calculated each time, first the calculation within the row and then the results of the calculation within the row are used to calculate between rows using this formula.

[0014] The above technical solution is used to achieve accurate image scaling interpolation calculation, so that the game screen maintains high quality and rich image details when switching between screens with different resolutions. Whether zooming in or out, players can clearly see the various elements in the game, enhancing the visual effects of the game.

[0015] Preferably, the output timing unit follows the VSYNC in the input video stream and intersperses appropriate leading and trailing shoulders and video blanking effective values ​​according to the principle of constant total time, thereby ensuring that the output follows the input timing in complete synchronization to avoid frame skipping and freezing.

[0016] The above technical solution ensures perfect synchronization between the output timing and the input timing, eliminates frame skipping and freezes. In the game, especially in high-speed action scenes, players can enjoy smooth and coherent pictures, which improves the consistency and accuracy of game operations.

[0017] Preferably, the MIPI encoding unit re-encodes the processed video stream into the MIPI format, and then encodes the VS-Start (01.00.00.ECC), HS-Start (21.00.00.ECC) and DE-Start (3E.00.00.ECC) in the video stream into a data packet format, and then inputs the underlying DPHY module in combination with the LP00-LP10-LP11 status, and finally forms a complete MIPI protocol format.

[0018] By adopting the above technical solution, the processed video stream is correctly encoded into a format that complies with the MIPI protocol, ensuring the accurate transmission and display of the video signal, so that the game screen can be presented on the screen in the correct format and parameters, with accurate colors and high clarity, bringing players a high-quality visual experience.

[0019] Preferably, the screen command unit inputs the initialization configuration file provided into the initialization module, uses unified 0x11 and 0x29 commands to light up the display screen, and communicates with the screen in real time through the command unit so that the screen adapts to different ambient brightness and performs real-time dimming.

[0020] By adopting the above technical solution, the screen initialization and real-time dimming functions are realized, so that the screen can automatically adjust according to the ambient brightness. During the game, no matter how the ambient light changes, the player can clearly see the game screen. At the same time, the fast response of the screen also ensures the timeliness and accuracy of the game operation.

[0021] Preferably, the ADC sampling unit loads a suitable resistor on the LCD backlight circuit, then connects the converted voltage to the ADC sampling pin of the FPGA, and finally records the voltage values ​​corresponding to different brightness values ​​to form a mathematical model, and matches the register value in OLDE corresponding to the LCD dimming process through the tested mathematical model.

[0022] The above technical solution successfully solves the problem of differences in LCD and OLED dimming methods and achieves precise dimming control. In the game, the screen brightness can be automatically adjusted according to the scene requirements, which not only protects the player's eyes, but also improves the contrast and layering of the game screen, enhancing the immersion of the game.

[0023] Compared with the prior art, the beneficial effects of the present invention are: the FPGA-based LCD screen replaces the OLED system:

[0024] 1. A scaling interpolation unit based on FPGA internal RAM cache is used to solve the problem of inconsistent resolution between LCD and OLED screens. It is highly flexible and adaptable. The system ensures the quality and integrity of the image through precise interpolation calculation and scaling processing, improves the visual experience, and enables users to fully utilize the advantages of high resolution of OLED screens after replacing the screen, while avoiding problems such as image deformation, blur or incomplete display caused by resolution mismatch.

[0025] 2. By loading appropriate resistors on the LCD backlight circuit and performing ADC sampling, a mathematical model of voltage and brightness values ​​is established to match the register values ​​in the OLED. This successfully solves the problem of the difference in LCD and OLED dimming methods. After the screen is replaced, a smooth and accurate dimming function can be achieved. Whether under different ambient light conditions or when the user adjusts the screen brightness according to personal preferences, the system can ensure the stability and reliability of the dimming process. Compared with traditional LCD dimming methods, OLED dimming can be more precise and can achieve lower brightness levels. At the same time, it avoids the flicker problem that may occur in LCD at low brightness, thereby reducing eye fatigue and damage;

[0026] Furthermore, this innovative dimming conversion method provides key technical support for the integration of two different display technologies, breaking the technical barriers that limit screen replacement due to different dimming methods, and promoting the upgrading and diversified development of display technology.

[0027] 3. The clock recovery unit uses the input MIPI-RX clock as a template to obtain all the clocks of the internal processing unit through the PLL. This technology is of great significance to the improvement of system performance and stability. During the screen replacement process, the processing of image data requires precise clock control, especially when it comes to operations such as image scaling based on the internal RAM cache. Through precise clock recovery, the system can ensure that during the data reading and writing process, data shift and overflow problems caused by clock deviation are avoided. This means that in every link of image transmission and processing, data can be operated according to the accurate timing, thereby ensuring the integrity and accuracy of the image;

[0028] Furthermore, when using a device with a replaced OLED screen, there will be no image anomalies, screen distortion or freezes. A stable and smooth visual experience can be obtained whether in static image display or dynamic video playback. From the perspective of overall system performance, clock recovery technology improves the reliability and stability of the system, providing a solid foundation for the normal operation of the device after the screen is replaced, and also enables the system to work stably in a complex electronic equipment environment and adapt to various application scenarios.

[0029] 4. The output timing unit ensures that the output timing is completely synchronized with the input timing by following the VSYNC (field synchronization signal) in the input video stream and adjusting the timing according to the principle of total time invariance, effectively preventing abnormal situations such as frame skipping and freeze, so that various image display scenes such as video playback and game operations can remain coherent and smooth. From the perspective of system compatibility, this output timing synchronization technology enables the screen replacement system to work better with other components of the original device, without the need for large-scale adjustments and modifications to the hardware architecture of the original device, reducing the difficulty and cost of system integration.

[0030] 5. The Lattice-XO3 selected by the system has the advantage of small size, which is of great significance in screen replacement applications. For electronic devices, the internal space is often very limited, especially in some portable devices such as mobile phones and tablets. The smaller FPGA size makes it easier to integrate into the circuit board of the original device without making large-scale changes to the internal structure of the device. This not only reduces the difficulty and cost of installation, but also reduces the compatibility issues that may be caused by hardware changes. After the user replaces the screen, the overall appearance and size of the device will not be significantly affected, and the original portability and aesthetics will still be maintained.

[0031] Furthermore, after the screen is replaced, the overall power consumption of the device will not increase significantly due to the addition of the new system. The device can be used for a longer time without frequent charging, which improves the convenience of using the device. At the same time, low power consumption also helps to reduce the heat problem of the device during operation, extend the service life of the device, and reduce the risk of hardware failure due to overheating. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the screen replacement principle of the present invention;

[0033] Figure 2 It is a schematic diagram of the screen replacement system framework of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figure 1-Figure 2 The present invention provides a technical solution: an FPGA-based LCD screen replacement OLED system.

[0036] Example

[0037] 1. Preparation for implementation

[0038] 1. Equipment and tool preparation

[0039] A smartphone with a typical LCD screen is selected as the implementation object, with a screen resolution of 1080×2340 and a size of 6.1 inches;

[0040] Prepare an OLED screen that fits the size of the phone, with a resolution of 1440×3120 and a size of 6.1 inches. This OLED screen has self-luminous characteristics, a contrast ratio of 100000:1, a brightness of up to 800 nits, and a pixel density of 538ppi;

[0041] The Lattice-XO3FPGA development board is selected as the core processing unit. It has 5280 logic units, 176 I / O pins, and an operating frequency of up to 500MHz. It has sufficient logic resources and I / O pins to meet system requirements.

[0042] Prepare several electronic components such as resistors and capacitors. The specific parameters are as follows:

[0043] Resistors: Select 10kΩ, 1kΩ, and 100Ω chip resistors with an accuracy of ±5% for circuit functions such as voltage division and current limiting;

[0044] Capacitors: 10μF, 0.1μF ceramic capacitors and 100μF electrolytic capacitors are selected, with withstand voltages of 16V, 50V, and 10V respectively, for circuit functions such as filtering and decoupling;

[0045] Electronic welding tools, including electric soldering iron (power 30W, temperature adjustable range 200℃-450℃), solder wire (diameter 0.8mm, tin content 63%), flux (rosin-based flux), etc., used to connect the OLED screen with the FPGA development board and the mobile phone motherboard;

[0046] The oscilloscope with MIPI interface test function, model Tektronix MDO3000, has a bandwidth of 1 GHz and a sampling rate of 5 GS / s, and is used to monitor and analyze signals during the debugging process.

[0047] 2. Software and Data Preparation

[0048] Download and install the development environment software for the FPGA development board, such as LatticeDiamond, to write and debug the FPGA logic code;

[0049] Obtain the LCD screen initialization configuration file and related register parameter information provided by the mobile phone manufacturer so as to make corresponding configuration adjustments after the screen is replaced. The LCD screen initialization command includes setting the pixel format to RGB565, the frame refresh rate to 60Hz, and the scanning mode to progressive scanning;

[0050] Prepare the initialization configuration file and driver provided by the OLED screen manufacturer to ensure that the OLED screen can be initialized and work correctly. The initialization parameters of the OLED screen include setting the pixel arrangement to Pentile, the display mode to normal mode, and the Gamma correction value to 2.2;

[0051] Establish a database containing different brightness values ​​and corresponding voltage values ​​for data comparison and register value matching during ADC sampling. In the initial test, the voltage values ​​corresponding to the lowest brightness to the highest brightness (0-255 brightness levels) range from 0.1V to 3.3V, and the sampling and recording are performed at intervals of 10 brightness levels. This database will be continuously improved and optimized during the subsequent debugging process;

[0052] 2. Implementation steps

[0053] 1. Hardware connection and installation

[0054] Remove the original LCD screen of the mobile phone from the mainboard, and be careful not to damage other parts of the mobile phone. During the disassembly process, record the interface type between the LCD screen and the mainboard as MIPIDSI interface, and the pin definition includes data channels 0-3, clock channel, power pin, and control pin;

[0055] Connect the OLED screen's flat cable to the corresponding interface on the FPGA development board. According to the specifications of the OLED screen and the pin assignment of the FPGA, design and make a suitable interface adapter board to ensure the correct transmission of the signal. During the connection process, use welding tools to firmly weld the flat cable to the pins on the adapter board to ensure a reliable connection and avoid problems such as cold soldering or short circuit. When welding, set the soldering iron temperature to 350℃ and control the welding time to 3-5 seconds to ensure welding quality.

[0056] Connect the FPGA development board to the MIPI interface on the mobile phone motherboard through another set of cables. This set of cables needs to be customized according to the interface definition of the mobile phone motherboard and the FPGA development board to ensure the compatibility and integrity of the signal. After the connection is completed, fix the FPGA development board and the OLED screen in a suitable position inside the mobile phone to ensure that they will not affect the normal operation of other components of the mobile phone. At the same time, ensure good heat dissipation. Stick a heat dissipation silicone sheet on the back of the FPGA development board and the OLED screen to enhance the heat dissipation effect;

[0057] 2.FPGA logic code development and configuration

[0058] In the development environment software LatticeDiamond, create a new project and write the FPGA logic code according to the functional requirements of the system;

[0059] Implement the functions of the MIPI decoding unit: including video stream parsing and command handshake protocol. According to the MIPI protocol specification, write code to identify the switching of LP state. When it is detected that the LP state switches from LP11-LP01-LP00 to high-speed mode, start parsing the packet header 00-00-00-00-00-B8 in the high-speed signal, and then analyze the command packet SOT / EOT, etc., and extract the video data stream signal from it. For the command handshake protocol, set the detection cycle to 10μs, detect the commands sent by the host in real time, analyze the commands that need to be answered, and perform handshake processing to ensure that the host will not enter the sleep state due to lack of response;

[0060] Design and implement RAM image cache unit: Since the resolution of OLED screen is higher than that of original LCD screen, the image needs to be scaled. According to the resource of RAM inside FPGA, 1MB cache space is allocated to store image data. Code is written to implement image data cache and read control logic. The cache write clock frequency is set to 100MHz and the read clock frequency is set to 120MHz to ensure the correct storage and reading of data during the scaling process.

[0061] Develop a clock recovery unit: Using the input MIPI-RX clock as a reference, generate various clock signals required by the internal processing unit through the PLL module, configure the PLL parameters so that the output clock frequencies are 120MHz, 150MHz, 200MHz, etc., and the phase shift is controlled within ±1° to meet the system's accuracy requirements and ensure that there will be no data shift and overflow problems during image scaling and processing;

[0062] Write the code for the scaling interpolation unit: According to the predetermined interpolation algorithm, the scaling function from the original LCD screen resolution (1080×2340) to the OLED screen resolution (1440×3120) is realized. For each pixel, four adjacent points are obtained from the RAM cache for bilinear calculation. The decimal part of the coordinate is used as the interpolation coefficient K. The interpolated pixel value is calculated according to the formula K*X+(1-K)Y. The intra-row calculation is performed first, and 2 pixels are calculated each time. After the calculation of one row is completed, the inter-row calculation is performed again, and the scaling of the entire image is gradually completed. During the calculation process, the data processing accuracy is set to 16 bits to ensure image quality;

[0063] Construct output timing unit: monitor the VSYNC field synchronization signal in the input video stream, calculate and generate appropriate front and rear shoulder and video blanking effective values ​​according to the principle that the total time of each frame is 1 / 60 seconds at a 60 refresh rate, set the front shoulder time to 10μs, the rear shoulder time to 20μs, and the video blanking time to 5μs, to ensure that the output video timing is completely synchronized with the input timing to avoid frame skipping and freeze;

[0064] Implement the function of the MIPI encoding unit: according to the packaging method specified in the MIPI protocol, encode the processed video stream data into a data packet format, including VS-Start (01.00.00.ECC), HS-Start (21.00.00.ECC) and DE-Start (3E.00.00.ECC), combine the encoded data packet with the LP00-LP10-LP11 status, and input it into the underlying DPHY module according to the timing requirements of the MIPI protocol, and finally form a complete MIPI protocol format. Set the data packet transmission rate to 1Gbps to meet the needs of high-speed data transmission;

[0065] Implement the function of the screen command unit: According to the initialization configuration file provided by the OLED screen manufacturer, input the resolution information (1440×3120), pixel pitch (0.05mm), scanning mode (progressive scanning), Gamma correction value (2.2) and other parameters into the initialization module. Finally, use the unified 0x11 and 0x29 commands to light up the display. During the use of the screen, in order to adapt to different ambient brightness, the command unit communicates with the screen in real time, and sets the dimming step to 10 levels, that is, from the lowest brightness to the highest brightness, it is divided into 100 levels. According to the feedback value of the ambient light sensor, the brightness of the OLED screen is adjusted in real time;

[0066] To realize the function of the ADC sampling unit: a 1kΩ resistor is loaded on the LCD backlight circuit, and then the converted voltage is connected to the ADC sampling pin of the FPGA; the ADC sampling frequency is set to 1kHz, and the voltage at different brightness values ​​is sampled. Finally, the voltage values ​​corresponding to different brightness values ​​are recorded to form a mathematical model. Based on the tested mathematical model, the register value in the OLED corresponding to the LCD dimming process is matched through a lookup table or algorithm calculation to achieve accurate dimming control;

[0067] 3. System debugging and optimization

[0068] 1. Functional testing

[0069] Turn on the phone, check whether the screen can light up normally, whether the displayed image is clear and complete, whether there is screen distortion, flickering, etc., observe whether the color display is normal, and compare the color saturation, contrast and other indicators of the OLED screen and the original LCD screen to ensure that the advantages of the OLED screen can be reflected;

[0070] Test whether the touch function is normal: by clicking, sliding and other operations on the screen, check whether the touch response is accurate and sensitive, and whether the interaction with the mobile phone system is smooth;

[0071] Verify the video playback function: Play video files with different resolutions and frame rates to see if the video plays smoothly, whether the images are synchronized, and whether there are any freezes or frame skips. Also, check the color reproduction and clarity of the video, especially when playing high-definition videos, and observe the OLED screen's ability to express details.

[0072] 2. Performance Testing

[0073] Use professional testing software, such as DisplayMate, to test various performance indicators of the OLED screen, including brightness uniformity, color accuracy, contrast, and viewing angle. Record the test data and compare it with the specifications of the OLED screen to ensure that the screen performance meets the expected requirements.

[0074] Test the power consumption of the system: Use a power analyzer to measure the power consumption changes of the phone in different working states (such as standby, talking, surfing the Internet, gaming, etc.), compare the power consumption data before and after replacing the OLED screen, evaluate the power consumption optimization effect of the system, and ensure that the battery life of the phone will not be significantly affected after the screen upgrade, and may even be improved in some cases (for example, due to the self-luminous characteristics of the OLED screen, the power consumption is lower when displaying black).

[0075] Test the response time of the system: including screen touch response time, system interface switching time, etc. Use high-speed cameras and professional testing tools to record and analyze the response time of the system under different operations to ensure that it meets the user's requirements for smooth operation. The response time should be controlled within the range that the human body can perceive. Generally, the touch response time does not exceed 100ms, and the system interface switching time does not exceed 500ms.

[0076] 3. Debugging and Optimization

[0077] According to the results of functional and performance tests, debug and optimize the system. If problems are found in the image display, such as noise and stripes, check the code logic of the MIPI decoding unit and encoding unit, and whether the hardware connection is reliable to ensure the correct parsing and transmission of the video stream data;

[0078] For the problem of inaccurate colors: adjust the Gamma correction value and color space conversion algorithm, and continuously optimize the color parameters by comparing the standard color samples with the actual display effects to achieve more accurate color reproduction;

[0079] If the touch response is not sensitive or there is false touch, check the configuration of the touch driver and touch controller, optimize the touch algorithm, adjust the touch sensitivity and threshold, and ensure the accuracy and stability of the touch operation.

[0080] In terms of power consumption optimization: if the power consumption is too high, analyze the power consumption distribution of each module of the system and find the part with large power consumption. If the power consumption of FPGA is too high, optimize its logic code, reduce the operating frequency or reduce unnecessary logic operations. For OLED screen, adjust its brightness control strategy and reduce the screen brightness to reduce power consumption while ensuring the display effect.

[0081] To address the problem of long system response time: optimize the system's software architecture and algorithm flow, improve data processing speed, optimize the image scaling and interpolation algorithm, reduce the amount of calculation, optimize the data transmission rate and timing control of the MIPI interface, ensure that data can be transmitted to the screen quickly and accurately, thereby shortening the response time.

[0082] Test Results

[0083] 1. Image display quality test results

[0084] 1. Resolution adaptation test

[0085] Test equipment and methods: Professional image analysis software ImageJ was used to analyze the display images after the OLED screen was replaced by LCD devices with different resolutions (three devices with resolutions of 720p and 1080p were selected respectively). Standard test patterns, including lines, grids, and fine text, were displayed on the screen, and the actual resolution and clarity of the image on the OLED screen were measured by the software.

[0086] Test result data:

[0087] After the 720p LCD device was replaced with an OLED screen, the actual resolution of the image on the OLED screen reached the expected target resolution, with an average error within ±2 pixels;

[0088] In terms of image clarity, by calculating the edge sharpness and modulation transfer function (MTF) of the image, it is found that the MTF value in the high-frequency part is significantly improved compared with the original LCD screen, with an average improvement of about 20%. When displaying lines and text, the edges are clearer and the recognizability is significantly improved;

[0089] After replacing the 1080p LCD device with an OLED screen, the resolution adaptation is still accurate, with an average error of less than ±1 pixel, and the image details are more outstanding;

[0090] When displaying complex patterns, more details can be clearly distinguished, and the overall clarity score of the image (calculated based on the weighted calculation of multiple clarity indicators) is about 15% higher than that of the original LCD screen;

[0091] 2. Color performance test

[0092] Test equipment and methods: A professional color calibrator (X-Rite i1 Pro) was used to measure the color of the OLED screen and the original LCD screen. Under the same test environment (standard light source D65, brightness of 200 nits), a series of standard color samples were displayed, and the color parameters of the OLED screen and LCD screen were recorded, including color gamut coverage, color accuracy (ΔE value) and color saturation.

[0093] Test result data:

[0094] Color gamut coverage: The color gamut coverage of the OLED screen is 96% NTSC, while the color gamut coverage of the original LCD screen is 75% NTSC, which is 21 percentage points higher.

[0095] Color accuracy (ΔE value): The average ΔE value of the OLED screen is less than 2 (the smaller the ΔE value, the higher the color accuracy). When displaying common colors, the ΔE value is mostly between 1-1.5, and the average ΔE value of the original LCD screen is between 3-4; when displaying red, the ΔE value of the OLED screen is 1.2, and the ΔE value of the LCD screen is 3.5; when displaying green, the ΔE value of the OLED screen is 1.1, and the ΔE value of the LCD screen is 3.8;

[0096] Color saturation: Through the analysis of multiple color samples, it is found that when the OLED screen displays bright colors, the colors are more intense and vivid. When displaying blue, the color saturation value of the OLED screen is 85%, while the color saturation value of the LCD screen is 65%, an increase of 20 percentage points;

[0097] 3. Contrast test

[0098] Test equipment and methods: Use a brightness meter to measure the brightness of the OLED screen and LCD screen when displaying all-black and all-white images, respectively, and calculate the contrast ratio. The test is carried out in a dark room to reduce the influence of ambient light.

[0099] Test result data:

[0100] The contrast ratio of OLED screens reaches over 100000:1, while the contrast ratio of original LCD screens is usually between 1000:1-1500:1. The brightness of OLED screens when displaying all-black images is 0.01 nits, and the brightness when displaying all-white images is 100 nits, with a contrast ratio of 10000:1. The brightness of original LCD screens when displaying all-black images is 0.5 nits, and the brightness when displaying all-white images is 500 nits, with a contrast ratio of 1000:1. The contrast ratio of OLED screens has been significantly improved compared with LCD screens, making the image layering more distinct and the dark details more clearly visible.

[0101] 2. System performance test results

[0102] 1. Frame rate and fluency test

[0103] Test equipment and methods: Monitor the frame rate of the input video stream through professional video frame rate test software (such as Fraps), play different types of videos (including high-definition movies, game videos, and dynamic demonstration videos, etc.) on the OLED screen, and use a high-speed camera to record the screen image to analyze the smoothness of the image and whether there are frame skipping, freezes, etc.

[0104] Test result data:

[0105] When the input video stream frame rate is 30fps and 60fps, the output frame rate on the OLED screen after system processing is kept stable at the same level as the input frame rate, and the frame rate fluctuation range is within ±0.5fps. When playing high-definition movies, there is no frame skipping or stuttering during the entire playback process, and the picture fluctuates smoothly. By analyzing the pictures recorded by the high-speed camera frame by frame, it is found that in the video played continuously for 1 hour, the number of frame skipping is 0, and the total stuttering time does not exceed 1 second. The stuttering phenomenon is very slight and hardly affects the viewing experience. When playing game videos and dynamic demonstration videos, the pictures can also be displayed in real time and accurately, with fast response speed, meeting the user's requirements for smoothness.

[0106] 2. Response time test

[0107] Test equipment and methods: A response time tester (Tektronix TDS3000 series oscilloscope) was used to measure the response time of the OLED screen and the original LCD screen. A rapidly changing black and white pattern was displayed on the screen, and the time interval from signal input to the corresponding change displayed on the screen was measured by the oscilloscope.

[0108] Test result data:

[0109] The average response time of the OLED screen is 0.1ms-0.5ms, while the response time of the original LCD screen is usually between 5ms-10ms. On the test equipment, the response time of the OLED screen is 0.3ms, and the response time of the LCD screen is 8ms. The response time of the OLED screen is significantly shorter than that of the LCD screen, which makes it possible to capture every instant change more clearly and accurately when displaying fast-moving images, reducing the occurrence of smear and blur. The advantages of the OLED screen are particularly obvious when performing fast-sliding screen operations or watching high-speed moving objects, and users can experience a smoother and clearer visual experience;

[0110] 3. Power consumption test results

[0111] 1. Test equipment and methods: Use a power analyzer (Keysight N6705C) to measure the power consumption of the FPGA-based LCD screen replacement OLED system in different working states (standby, playing videos, running games), and compare it with the power consumption of the original LCD screen system. The test is carried out under the same environmental conditions and the brightness of the equipment is set to the same level (200 nits).

[0112] 2. Test result data:

[0113] Standby power consumption:

[0114] The average standby power consumption of the FPGA-based OLED system is 0.1W-0.3W, while the average standby power consumption of the original LCD screen system is 0.5W-1W. On the test equipment, the standby power consumption of the OLED system is 0.2W, and the standby power consumption of the LCD system is 0.8W. The standby power consumption of the OLED system is reduced by about 75%;

[0115] Power consumption when playing video:

[0116] When playing 1080p HD video, the average power consumption of the OLED system is 1.5W-2W, while the average power consumption of the original LCD screen system is 2.5W-3W. On the test equipment, the power consumption of the OLED system is 1.8W, while the power consumption of the LCD system is 2.8W. The power consumption of the OLED system is reduced by about 36%.

[0117] Power consumption when running games:

[0118] When running large 3D games, the average power consumption of the OLED system is 2.5W-3.5W, while the average power consumption of the original LCD screen system is 4W-5W. On the test equipment, the OLED system consumes 3W when running games, while the LCD system consumes 4.5W when running games. The power consumption of the OLED system is reduced by about 33%;

[0119] 4. Stability and reliability test results

[0120] 1. Long-running tests

[0121] Test equipment and methods: Replace the OLED system with an FPGA-based LCD screen and put it into continuous operation. Use automated test software to continuously loop videos, run applications, and perform screen operations. Record the system's fault conditions and performance changes during operation. The test lasts for 72 hours.

[0122] Test result data:

[0123] During the 72-hour continuous operation test, the system did not freeze, restart or have other serious faults. Only once at the 48th hour of operation, there was a brief screen flickering phenomenon, but the system automatically recovered to normal in about 0.5 seconds. The performance of the system remained basically stable throughout the test, and indicators such as CPU usage and memory occupancy did not show obvious fluctuations. The CPU usage was 30%-40% at the beginning of the test and remained in the range of 30%-40% at the end of the test. The memory usage remained between 60%-70% during the test.

[0124] 2. Environmental adaptability test

[0125] Test equipment and methods: The system was placed under different environmental conditions, including a temperature range of -20°C to 60°C and a humidity range of 20%RH to 90%RH, and an electromagnetic interference test was performed (using a standard electromagnetic interference generator to apply electromagnetic interference signals of different intensities), and the working status and image display quality of the system under these environments were observed;

[0126] Test result data:

[0127] In the temperature test:

[0128] When the ambient temperature is -20℃, the system startup time is slightly extended, about 1.2 times the normal startup time, but it can work normally after startup, and there is no obvious abnormality in the image display. The screen brightness and color are slightly reduced, and the brightness reduction is about 10%, but it can still be viewed clearly;

[0129] In a high temperature environment of 60℃, the system runs stably, the image is displayed normally, the screen brightness increases slightly by about 5%, and there is no overheating, freezing or other malfunctions.

[0130] In humidity testing:

[0131] In a dry environment with a humidity of 20% RH, the system works normally without any abnormal phenomenon;

[0132] When the humidity reaches 90%RH, the system runs stably and the image is clear without any problems such as short circuit, leakage or blurred image.

[0133] In the electromagnetic interference test:

[0134] When the applied electromagnetic interference intensity is less than 1V / m, the system is not affected, and the image display and performance are normal;

[0135] When the electromagnetic interference intensity is between 1V / m and 5V / m, the system will have slight image noise, but it will not affect normal viewing and use;

[0136] When the electromagnetic interference intensity is greater than 5V / m, the image flickers and is distorted briefly, but the system can still keep running without serious problems such as freezing or data loss. After removing the electromagnetic interference, the system can quickly return to normal working state;

[0137] Through the above detailed test results, it can be seen that the FPGA-based LCD screen replacement OLED system has achieved good results in image display quality, system performance, power consumption, stability and reliability, and can provide users with a better visual experience and more reliable use guarantee.

[0138] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. An FPGA-based LCD screen replacement OLED system, characterized by: It includes MIPI decoding unit, RAM image cache unit, clock recovery unit, scaling interpolation unit, output timing unit, MIPI encoding unit, screen command unit and ADC sampling unit. The FPGA selected for this system is only Lattice-XO3.

2. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The MIPI decoding unit consists of two parts: video stream analysis and command handshake protocol; The analysis of MIPI video stream first analyzes the LP state switching from LP11-LP01-LP00 to high-speed mode, then analyzes the packet header 00-00-00-00-00-B8 in the high-speed signal, and then analyzes the command packet SOT / EOT ​​to parse the video data stream signal; The command handshake protocol detects the commands sent by the host, analyzes the commands that need to be answered, and performs handshake processing. If the host does not receive a response, it will enter a dormant state.

3. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The RAM image cache unit ensures the consistency of screen display specifications by scaling the screen display resolution.

4. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The clock recovery unit obtains all clocks of the internal processing unit based on the input MIPI-RX clock as a template through the PLL, thereby preventing the data in the RAM from slowly shifting during the read-write process and eventually causing data overflow.

5. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The points in the interpolation system of the scaling interpolation unit are bilinearly calculated through four points obtained from the RAM cache. The decimal part of the coordinates is the interpolation coefficient K, and the formula is as follows: K*X+(1-K)Y. Two pixels are calculated each time. The calculation is first performed within the row and then the results of the calculation within the row are used to calculate the inter-row space using this formula.

6. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The output timing unit follows the VSYNC in the input video stream and inserts appropriate front and back shoulders and video blanking effective values ​​according to the principle of unchanged total time, ensuring that the output is completely synchronized with the input timing to avoid frame skipping and freezes.

7. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The MIPI encoding unit re-encodes the processed video stream into the MIPI format, and then encodes the VS-Start (01.00.00.ECC), HS-Start (21.00.00.ECC) and DE-Start (3E.00.00.ECC) in the video stream into a data packet format, and then inputs the underlying DPHY module in combination with the LP00-LP10-LP11 status, and finally forms a complete MIPI protocol format.

8. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The screen command unit inputs the initialization configuration file provided into the initialization module, uses the unified 0x11 and 0x29 commands to light up the display screen, and communicates with the screen in real time through the command unit to adjust the screen to different ambient brightness in real time.

9. The FPGA-based LCD screen replacement OLED system according to claim 1, characterized in that: The ADC sampling unit loads a suitable resistor on the LCD backlight circuit, then connects the converted voltage to the ADC sampling pin of the FPGA, and finally records the voltage values ​​corresponding to different brightness values ​​to form a mathematical model. The tested mathematical model is used to match the register value in OLDE corresponding to the LCD dimming process.

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