Patent Application
20250232736
The present disclosure relates to a display device, a backlight control circuit, and a backlight control method, and more particularly to a display device, a backlight control circuit, and a backlight control method with a feed-forward adjustment mechanism for adjusting an operating voltage of a backlight module.
A backlight system in a conventional display device is used to provide a backlight source for a display panel displaying a frame image. For a display device with a local dimming function, the backlight system includes a backlight module, a power supply circuit, a backlight driving circuit, and a local dimming circuit. When the display panel displays a frame image, the power supply circuit provides a required operating voltage to the backlight module, and the backlight driving circuit adjusts the supplied backlight driving signals based on the local dimming signal of the local dimming circuit to change the current values flowing through the backlight module, thereby adjusting the brightness of the backlight module. Some backlight systems also include a feedback mechanism that monitors the actual brightness of the backlight module and adjusts the operating voltage and the driving currents accordingly to ensure that the brightness of the backlight module always matches the desired value for providing a more stable display.
However, the adjustment of the operating voltage and the driving current depends on the response rate of the feedback circuit and the backlight driving circuit. A slow response rate of the backlight driving circuit will result in a slower supply of the driving currents to the backlight module, which affects the control time point of the feedback circuit and results in a longer stabilization time for the driving current and a higher power loss. Moreover, when the screen changes rapidly, dynamic adjustment of the operating voltage using the feedback mechanism may result in a situation where the operating voltage does not follow immediately.
The present disclosure provides a backlight control circuit including a power supply circuit, a local dimming circuit, a backlight driving circuit, and a supply voltage adjustment circuit. The power supply circuit is used to output a power supply voltage to the backlight module. The backlight module has a plurality of dimming zones, and each dimming zone includes a plurality of light emitting diodes (LEDs). The local dimming circuit is used to generate a local dimming signal based on an image data and a configuration of the dimming zones. The backlight driving circuit is used to generate a plurality of backlight driving signals based on the local dimming signal. The supply voltage adjustment circuit is used to generate a first supply voltage adjustment signal to the power supply circuit for adjusting the power supply voltage based on the local dimming signal and a characteristic data of each LED in the dimming zones.
According to one embodiment of the present disclosure, the local dimming signal includes a plurality of luminance values corresponding to the dimming zones in the image data, and the luminance values are provided to the backlight driving circuit to generate the backlight driving signals accordingly.
According to one embodiment of the present disclosure, each of the backlight driving signals is a current driving signal, and the characteristic data includes a relationship data between an operating voltage and an operating current of each LED in the dimming zones.
According to one embodiment of the present disclosure, the supply voltage adjustment circuit is further configured to generate a second supply voltage adjustment signal to the power supply circuit to adjust the power supply voltage in response to the power supply voltage being out of a voltage range corresponding to the image data, and wherein the second supply voltage adjustment signal is generated based on a detection signal of each LED in the dimming zones.
According to one embodiment of the present disclosure, the supply voltage adjustment circuit includes an analog regulation circuit. The analog regulation circuit is used to decrease a level of the power supply voltage in response to an increasing level of the second supply voltage adjustment signal, and to increases the level of the power supply voltage in response to a decreasing level of the second supply voltage adjustment signal.
According to one embodiment of the present disclosure, the detection signal is a cathode voltage of each LED.
According to one embodiment of the present disclosure, the detection signal is generated by the backlight driving circuit detecting a cathode voltage of each LED.
The present disclosure provides a display device including a display panel, a backlight module, a power supply circuit, a power supply circuit, a backlight driving circuit, a supply voltage adjustment circuit. The display panel is used to display a frame image based on an image data. The backlight module is used to provide a backlight source to the display panel. The backlight module has a plurality of dimming zones, and each dimming zone includes a plurality of light emitting diodes (LEDs). The power supply circuit is used to output a power supply voltage to the backlight module. The local dimming circuit is used to generate a local dimming signal based on an image data and a configuration of the dimming zones. The backlight driving circuit is used to generate a plurality of backlight driving signals to the dimming zones of the backlight module based on the local dimming signal. The supply voltage adjustment circuit is used to generate a supply voltage adjustment signal to the power supply circuit for adjusting the power supply voltage based on the local dimming signal and a characteristic data of each LED in the dimming zones.
According to one embodiment of the present disclosure, the power supply circuit is configured to adjust the power supply voltage according to the supply voltage adjustment signal before the display panel displays the frame image.
According to one embodiment of the present disclosure, each of the backlight driving signals is a current driving signal, and the characteristic data includes a relationship data between an operating voltage and an operating current of each LED in the dimming zones.
The present disclosure provides a backlight control method including providing a power supply voltage to a backlight module; generating a local dimming signal based on an image data and a configuration of a plurality of dimming zones in the backlight module, in which each dimming zone includes a plurality of light emitting diodes (LEDs); generating a plurality of backlight driving signals to the dimming zones of the backlight module based on the local dimming signal; generating a first supply voltage adjustment signal based on the local dimming signal and a characteristic data of each LED in the dimming zones; and adjusting the power supply voltage according to the first supply voltage adjustment signal.
According to one embodiment of the present disclosure, the power supply voltage is adjusted according to the first supply voltage adjustment signal is performed before a frame image based on the image data is displayed on a display panel provided with a backlight source by the backlight module.
According to one embodiment of the present disclosure, each of the backlight driving signals is a current driving signal, and the characteristic data comprises a relationship data between an operating voltage and an operating current of each LED in the dimming zones.
According to one embodiment of the present disclosure, the backlight control method further includes generating a second supply voltage adjustment signal based on a detection signal of each LED in the dimming zones in response to the power supply voltage being out of a voltage range corresponding to the image data; and adjusting the power supply voltage based on the second supply voltage adjustment signal.
According to one embodiment of the present disclosure, adjusting the power supply voltage based on the second supply voltage adjustment signal includes decreasing a level of the power supply voltage in response to a level of the second supply voltage adjustment signal increasing, and increasing the level of the power supply voltage in response to the level of the second supply voltage adjustment signal decreasing.
According to one embodiment of the present disclosure, the detection signal is a cathode voltage of each LED.
According to one embodiment of the present disclosure, the backlight control method further includes detecting a cathode voltage of each LED to generate the detection signal.
In order that the foregoing and other objects, features, advantages and embodiments of the present disclosure may be more readily understood, the accompanying drawings are illustrated as follows.
Referring to
Referring to
In some embodiments, as shown in
The power supply circuit 121 may be a linear power supply or a switching power supply, and the power supply voltage VLED output from the power supply circuit 121 may be realized by analog or digital means for feedback control, and the present disclosure is not limited thereto.
The local dimming signal SLD includes the luminance values (or dim levels) corresponding to each of the dimming zones LDa in the image data, and these luminance values are provided to the backlight driving circuit 123 to generate the corresponding backlight driving signals SBD. The backlight driving signal SBD may be a current driving signal, which is used to control the current value flowing through each LED in each dimming zone LDa. The required current of each channel of the backlight driving circuit 123 (or LED driver IC) is then obtained according to the information of the backlight driving circuit 123 corresponding to each dimming zone LDa, ensuring that each dimming zone LDa produces the corresponding brightness.
The characteristic data includes a relationship data between the operating voltage VF and the operating current IF of each LED in each dimming zone LDa. The characteristic data may be pre-built into the supply voltage adjustment circuit 124 to calculate the basic power supply voltage VLED required to illuminate these dimming zones LDa as soon as the supply voltage adjustment circuit 124 receives the local dimming signal SLD. Then, the supply voltage adjustment circuit 124 generates a first supply voltage adjustment signal V1 to the power supply circuit 121 to adjust the power supply voltage VLED to an appropriate value in advance. In other words, the DC output voltage of the power supply circuit 121 is controlled. Ultimately, the power supply voltage VLED of the power supply circuit 121 is controlled within a reasonable range, which has the advantage of faster real time regulation.
The desired luminance values of the dimming zones LDa are proportional to the operating current IF. As shown in
In this embodiment, the power supply circuit 121 further includes an analog regulation circuit. As shown in
Specifically, the power supply circuit 121 decreases a level of the power supply voltage VLED when a level of the second supply voltage adjustment signal V2 increases, and increases the level of the power supply voltage VLED when the level of the second supply voltage adjustment signal V2 decreases. In this way, the second supply voltage adjustment signal V2 serves as an adjustment voltage for a feedback mechanism to fine-tune the power supply voltage VLED to a desired value. This feedback mechanism ensures that an actual operating voltage of each dimming zone LDa of the backlight module LD is within a preset voltage or within the voltage range corresponding to the image data.
In this embodiment, the backlight control circuit 120 further includes a timing controller for instructing the backlight control circuit 120 to control the backlight module LD according to the timing. Referring to
For example, during the time between the completion of image reception and the start of frame image display, the local dimming circuit 122 generates the corresponding backlight driving signals SBD according to the respective multiple luminance values (dim levels) in the image data. Therefore, the backlight driving circuit 123 may generate the corresponding backlight driving signals SBD in response to rapid screen changes. For example, at a frame rate of 60 Hz, the backlight driving circuit 123 may output the backlight driving signals SBD at a time of approximately 16.6 milliseconds (ms) from the completion of image reception to the start of screen display.
In some embodiments, the total operating voltage Vx required for each dimming zone LDa varies depending on the configuration of the LEDs, and thus the power supply circuit 121 may also supply the same (e.g., shared) or different power supply voltages VLED to each dimming zone LDa as desired. For example, the power supply circuit 121 may provide more power supply paths to the backlight modules LD, and these power supply paths may have different power supply voltages VLED. In some embodiments, the LEDs in each dimming zone LDa are connected in series and parallel, such that the LEDs form a plurality of sets of LED strings connected in parallel, and each set of LED strings may flow through the same or a different current and emit a corresponding luminance according to the currents flowing through them.
Referring to
At Step 210, the power supply circuit 121 continuously provides power supply voltage VLED to the backlight module LD during each frame period to illuminate each LED in each dimming zone LDa.
At Step 220, the local dimming circuit 122 receives an image data of a frame image to be displayed in the next frame and calculates the local dimming signal SLD required by the image data corresponding to a configuration of the dimming zones LDa.
At Step 230, the supply voltage adjustment circuit 124 receives the local dimming signal SLD and generates a first supply voltage adjustment signal V1 based on the local dimming signal SLD and a characteristics data of each LED in each dimming zone LDa.
At Step 240, the power supply circuit 121 adjusts the power supply voltage VLED to an appropriate value in advance based on the first supply voltage adjustment signal V1. Consequently, the stabilization of the driving current for each dimming zone LDa may be accelerated, and the power loss may be effectively reduced.
At Step 250, the backlight driving circuit 123 generates a corresponding backlight driving signal SBD for each dimming zone LDa of the backlight module LD based on the local dimming signal SLD to control the current value flowing through the LEDs in each dimming zone LDa and to cause them to emit a corresponding brightness.
In some embodiments, the backlight control method 200 further includes Step 260. When the power supply voltage VLED is out of a voltage range corresponding to the image data, the supply voltage adjustment circuit 124 generates a second supply voltage adjustment signal V2 based on a detected signal VD of each LED in the dimming zones LDa, and fine-tunes the power supply voltage VLED based on the second supply voltage adjustment signal V2. When a level of the second supply voltage adjustment signal V2 increases, the power supply circuit 121 decreases a level of the power supply voltage VLED. Conversely, when the level of the second supply voltage adjustment signal V2 decreases, the power supply circuit 121 increases the level of the power supply voltage VLED. As a result, the power supply voltage VLED may be fine-tuned to a desired value by the second supply voltage adjustment signal V2.
In some embodiments, the dimming zones LDa of the backlight module LD may be divided into a plurality of strip zones, and the luminance dimming of each strip zone is implemented as desired. In some embodiments, the backlight module LD may be divided into multiple columns and rows of array dimming zones, and the luminance dimming of the dimming zones of each column and row may be implemented as desired. It should be understood that any backlight module LD capable of implementing multi-zone dimming is within the scope of the present disclosure.
According to the display device, the backlight control circuit and the backlight control method of the present disclosure, based on the local dimming signal and the characteristic data of each LED in each dimming zone, the power supply voltage required for the backlight module of the next frame image is predicted, so that the starting control point of the power supply voltage of the power supply circuit is advanced, and the power supply voltage is adjusted to an appropriate value in advance. In conclusion, the present disclosure accelerates the speed of stabilizing the driving current required by each dimming zone and effectively reduces the power loss.
Although the present disclosure has been disclosed in embodiments as above, the embodiments are not intended to limit the present disclosure, and those skilled in the art may make some modifications and embellishments within the spirit and scope of the present disclosure, therefore, the scope of protection of the present disclosure shall be defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311427639.3 | Oct 2023 | CN | national |
This application is a continuation application of International Application No. PCT/CN2023/140564 filed on Dec. 21, 2023, which claims priority to China Application Serial Number 202311427639.3, filed Oct. 31, 2023. The entire contents of each of which are incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2023/140564 | Dec 2023 | WO |
| Child | 19097883 | US |
