Method suitable for switching different dimming modes of Mini LED television backlight

Abstract

The invention discloses a method suitable for switching different dimming modes of Mini LED television backlight, and the method comprises the steps: dynamically updating a current adjustment step according to the refresh rate of a screen, a voltage difference value from the current brightness to the target brightness, and a current difference value, gradually changing the LED current value, and adjusting the dimming modes of the Mini LED television backlight. The backlight control unit feeds back a voltage regulation signal to the power supply module according to a required voltage value corresponding to the current current value, the power supply module outputs a corresponding LED light control voltage, and voltage and current regulation of an LED lamp is completed, so that the brightness of a lamp bead is changed, and the brightness of a screen is further changed. The method is used for solving the problems of screen flashing, brightness sudden change, abnormal display and the like which are visible to naked eyes due to unbalanced, uneven, too fast or too slow voltage and current adjustment.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal television display technology, and in particular to a method for switching different dimming modes of MiniLED television backlight. Background Technology

[0002] Currently, MiniLED smart TVs have a significant advantage in the market due to their high contrast ratio, rich colors, excellent dark scene performance, and energy efficiency. More and more TV products are choosing zone-controlled TVs with individual lamp control. MiniLED TVs typically have three dimming modes: PWM dimming, which adjusts the pulse width to change the transistor's on-time; the longer the on-time, the higher the brightness, allowing for precise and stable dimming, but it can cause flicker. DC dimming directly changes the LED's brightness by altering the LED's drive current; it's simple to control, easy to implement, and flicker-free, but DC dimming can cause color shifts and cannot achieve fine-tuning. Hybrid dimming uses PWM dimming in some scenarios and DC dimming in others. Users can freely choose or add algorithms via software to automatically switch to DC mode in scenarios requiring high brightness and vibrant colors, while defaulting to PWM dimming in normal scenarios.

[0003] Because DC dimming and PWM dimming operate on different principles, some issues can arise during mode switching. Depending on the characteristics of the LED chips, different current values ​​require different voltages, resulting in varying luminous efficacy. The voltage and current supplied to LEDs in DC dimming and PWM dimming modes differ significantly. From a user perspective, if the switching is too rapid, brightness will abruptly change, severely impacting the user experience; if the switching is too slow, the brightness cannot keep up with the changing screen, similarly affecting the viewing experience. From a hardware and software perspective, sudden changes in voltage and current supplied to the LEDs during mode switching can affect the stability of the entire system and shorten the lifespan of components. If the current increases too quickly while the voltage increases too slowly, the voltage may not meet the LED's current requirements, causing the backlight control unit to mistakenly identify the LED as open-circuited, leading to chip errors. Conversely, if the voltage increases too quickly while the current increases too slowly, the LED chips and backlight control chip will be under high voltage for extended periods, causing their temperature to rise and affecting their reliability and stability. Therefore, how to adjust the voltage and current of LEDs during dimming mode switching is a critical issue that urgently needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for switching different dimming modes of MiniLED TV backlight to solve the above-mentioned problems. By dynamically updating the current adjustment step according to the screen refresh rate, the voltage difference between the current brightness and the target brightness, and the current difference, the LED current value is gradually changed. The backlight control unit feeds back the voltage adjustment signal to the power module according to the required voltage value corresponding to the current value. The power module outputs the corresponding LED light control voltage to complete the voltage and current adjustment of the LED lamp, thereby changing the brightness of the lamp and thus changing the screen brightness. This method is used to solve the problems of screen flicker, sudden brightness changes, and display abnormalities caused by unbalanced, uneven, too fast or too slow voltage and current adjustment.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] This invention provides a method for switching different dimming modes of MiniLED TV backlight, comprising the following steps:

[0007] Step S1: The main chip 20 identifies the current scene and reads the current screen brightness histogram data and screen refresh rate f.

[0008] Step S2: The current scene is identified using AI to obtain image information and determine whether it is a special scene. If it is a special scene, DC dimming mode is entered; otherwise, PWM dimming mode is entered.

[0009] Step S3: If DC dimming mode is entered, the dimming step is adapted to the refresh rate, and the light control current is gradually changed to achieve a steady adjustment from low current to high current or from high current to low current. The voltage is adjusted synchronously through the signal fed back from the driver chip feedback unit, and finally the backlight brightness is adjusted.

[0010] Step S4: If the PWM dimming mode is entered, the main chip calculates the required PWM duty cycle for each zone based on the current brightness and transmits it to the driver chip through the dimming signal to adjust the brightness of the LED.

[0011] As a preferred embodiment of the present invention, step S3 specifically includes: when entering DC dimming mode, Cnt starts counting from 0, and increments by one for each current adjustment; the current value dcVal, the target current value targetVal, and the object current value aDimmVal are calculated according to the formula:

[0012] ,

[0013] The difference between the target current and the object current is used as the adjustment value, and the object current value is used as the reference current. The current value adjusted in each step is dynamically adjusted according to the actual refresh rate until the count value Cnt equals the current refresh rate f. The target duty cycle (duty) changes based on the current duty cycle (temp), the current current value (dcVal), and the peak current (PeakVal). ,

[0014] The target duty cycle will change with the trend of the current value until it fully enters DC dimming mode and the duty reaches 100%.

[0015] As a preferred embodiment of the present invention, step S3 further includes the main chip 20 sending the current information corresponding to each partition to the backlight control unit 21. After receiving the partition current value, the backlight control unit 21 calculates the target voltage value, compares it with the current voltage value, and adjusts the output voltage value of the LED according to the feedback voltage signal power supply module 22.

[0016] As a preferred embodiment of the present invention, step S4 specifically includes exiting the DC dimming mode and entering the PWM dimming mode when the current scene does not belong to a special scene. Similar to step S3, the LED current value is gradually adjusted, with Cnt decreasing by one for each current adjustment until Cnt is 0. The duty cycle gradually decreases from 100% following the change in current value. The voltage changes synchronously with the current value. After entering the PWM dimming mode, the backlight control unit 21 changes the backlight brightness by changing the duty cycle of the PWM wave output to the LED, while the current amplitude remains unchanged. When brightness needs to be increased, the duty cycle is increased; when brightness needs to be decreased, the duty cycle is decreased.

[0017] As a preferred embodiment of the present invention, DC dimming is used for high-brightness images, and PWM dimming is used for normal or low-brightness images.

[0018] As a preferred embodiment of the present invention, the control voltage follows the change of the control current to ensure that the change trends and steps of the two are consistent.

[0019] The beneficial effects of this invention are as follows: The method of this invention can balance the adjustment speed of voltage and current, avoiding the problem of insufficient voltage division of the driver chip due to excessively fast current adjustment and slow voltage follow-up, which may lead to misidentification as an open circuit of the LED bead and thus cause an error, or excessively fast voltage adjustment and slow current adjustment may cause excessive voltage on the LED and driver chip. At the same time, it can also avoid sudden changes in voltage and current, which may cause the brightness of the display screen to jump and affect the viewing effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the backlight dimming process.

[0021] Figure 2 This is a system block diagram for backlight voltage and current regulation.

[0022] In the diagram: 20 - Main chip, 21 - Backlight control unit, 22 - Power module. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the implementation method of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the appendices in the embodiments of this application will be described below. Figure 1-2 The technical solutions in the embodiments of this application are described clearly and completely.

[0026] Step 1: The main chip 20 identifies the current scene and reads the current screen brightness histogram data and screen refresh rate f.

[0027] Step 2: Use AI to identify the current scene, obtain image information, and determine whether it is a special scene. If it is a special scene, enter DC dimming mode; otherwise, enter PWM dimming mode.

[0028] Step 3: When entering DC dimming mode, Cnt starts counting from 0. Cnt increments by one with each current adjustment. The current value is dcVal, the target current value is targetVal, and the target current value is aDimmVal. The formula is as follows: ,

[0029] The difference between the target current and the object current is used as the adjustment value, and the object current value is used as the reference current. The current value adjusted in each step is dynamically adjusted according to the actual refresh rate until the count value Cnt equals the current refresh rate f. The target duty cycle (duty) changes based on the current duty cycle (temp), the current current value (dcVal), and the peak current (PeakVal). ,

[0030] The target duty cycle will change with the trend of the current value until it fully enters DC dimming mode and the duty reaches 100%.

[0031] The main chip 20 sends the current information corresponding to each partition to the backlight control unit 21. After receiving the partition current value, the backlight control unit 21 calculates the target voltage value, compares it with the current voltage value, and feeds back the voltage signal to the power supply module 22. The power supply module 22 adjusts the output voltage value of the LED according to the feedback voltage signal.

[0032] Step 4: When the current scene does not belong to a special scene, exit DC dimming mode and enter PWM dimming mode. Similar to Step 3, gradually adjust the LED current value, decreasing Cnt by one with each current adjustment until Cnt reaches 0. The duty cycle gradually decreases from 100% following the change in current value. The voltage changes synchronously with the current value. After entering PWM dimming mode, the backlight control unit 21 changes the backlight brightness by changing the duty cycle of the PWM wave output to the LED, while the current amplitude remains unchanged. When brightness needs to be increased, the duty cycle is increased; when brightness needs to be decreased, the duty cycle is decreased.

[0033] As a preferred embodiment of the present invention, DC dimming is used for high-brightness images, and PWM dimming is used for normal or low-brightness images.

[0034] As a preferred embodiment of the present invention, the control voltage follows the change of the control current to ensure that the change trends and steps of the two are consistent.

[0035] This adjustment method can not only balance the adjustment speed of voltage and current, avoiding the situation where the driver chip receives too little voltage due to excessively fast current adjustment and slow voltage response, which may lead to errors due to misidentification of the LED bead as an open circuit, or excessively fast voltage adjustment and slow current adjustment that may cause excessive voltage on the LED and driver chip, but also avoid sudden changes in voltage and current that may cause abrupt changes in the brightness of the display screen and affect the viewing experience.

[0036] Although the present invention has been described herein with reference to illustrative embodiments, the above embodiments are merely preferred embodiments of the present invention, and the implementation of the present invention is not limited to the above embodiments. It should be understood that those skilled in the art can devise many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. A method for switching different dimming modes of MiniLED TV backlight, characterized in that, Includes the following steps: Step S1: The main chip 20 identifies the current scene and reads the current screen brightness histogram data and screen refresh rate f. Step S2: The current scene is identified using AI to obtain image information and determine whether it is a special scene. If it is a special scene, DC dimming mode is entered; otherwise, PWM dimming mode is entered. Step S3: If DC dimming mode is entered, the dimming step is adapted to the refresh rate, and the light control current is gradually changed to achieve a steady adjustment from low current to high current or from high current to low current. The voltage is adjusted synchronously through the signal fed back from the driver chip feedback unit, and finally the backlight brightness is adjusted. Step S4: If the PWM dimming mode is entered, the main chip calculates the required PWM duty cycle for each zone based on the current brightness and transmits it to the driver chip through the dimming signal to adjust the brightness of the LED.

2. The method for switching different dimming modes of MiniLED TV backlight according to claim 1, characterized in that, Step S3 specifically includes: when entering DC dimming mode, the counter value Cnt starts counting from 0, and increments by one for each current adjustment. The current value dcVal, the target current value targetVal, and the target current value aDimmVal are calculated according to the formula: ， The difference between the target current and the object current is used as the adjustment value, and the object current value is used as the reference current. The current value adjusted in each step is dynamically adjusted according to the actual refresh rate until the count value Cnt equals the current refresh rate f. The target duty cycle (duty) changes according to the current duty cycle (temp), the current current value (dcVal), and the peak current (PeakVal). , The target duty cycle will change with the trend of the current value until it fully enters DC dimming mode and the duty reaches 100%.

3. The method for switching different dimming modes of MiniLED TV backlight according to claim 1, characterized in that, Step S3 further includes the main chip 20 sending the current information corresponding to each partition to the backlight control unit 21. After receiving the partition current value, the backlight control unit 21 calculates the target voltage value, compares it with the current voltage value, and adjusts the output voltage value of the LED according to the feedback voltage signal power supply module 22.

4. The method for switching different dimming modes of MiniLED TV backlight according to claim 1, characterized in that, Step S4 specifically includes exiting DC dimming mode and entering PWM dimming mode when the current scene does not belong to a special scene. Similar to step S3, the LED current value is gradually adjusted. Each time the current is adjusted, Cnt decreases by one until Cnt is 0. The duty cycle gradually decreases from 100% following the change in current value. The voltage changes synchronously with the current value. After entering PWM dimming mode, the backlight control unit 21 changes the backlight brightness by changing the duty cycle of the PWM wave output to the LED lamp, while the current amplitude remains unchanged. When it is necessary to increase the brightness, the duty cycle is increased; when it is necessary to decrease the brightness, the duty cycle is decreased.

5. A method for switching different dimming modes of MiniLED TV backlight according to claim 1, characterized in that, High-brightness images use DC dimming, while normal or low-brightness images use PWM dimming.

6. The method for switching different dimming modes of MiniLED TV backlight according to claim 1, characterized in that, The voltage follows the change in current, ensuring that the trends and steps of the two changes are consistent.

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