TW201503095A - High performance LCD local dimming method and system thereof - Google Patents

Abstract

The invention related to the high performance LCD local dimming method and system thereof. Firstly, an image is divided into M x N blocks, and each of which corresponds to one lighting source in the backlight. Then, to use the local block mean variance finds the edge blocks. Finally, to use the enhancement factor finds the block backlighting level of LED. According to the LCD local dimming method and the technology of commonality accumulation variance, the instant wafer processing system can be achieved with FPGA chipset. It comprises a LED backlight unit, a register, and a local dimming chip unit. Accordingly, it can effectively reduce the cost of the hardware expenditures and preserve the important image information in the dark edge and to achieve fully the purposes of energy saving 50% and contrast up to 100 times.

Description

High-performance liquid crystal local dimming method and system thereof

The invention relates to a high-performance liquid crystal local dimming method and a system thereof, in particular to a technique and system for locally dimming a backlight source of a liquid crystal screen by using image feature values, for storing a dark portion. The important image edge information can effectively save the average power and improve the contrast; the invention also uses the high-efficiency local dimming method to design the instant wafer processing, and adopts the common accumulation variability technology to greatly reduce the cost of the hardware.

With the rapid development of electronic technology and mobile communication, people are increasingly demanding mobile display. The traditional cathode ray tube display has been inconvenient due to the cumbersome and unbearable shortcomings. Since the introduction of liquid crystal display products in 1990, The right angle of the plane and the display of the screen are not deformed, light and short, and low energy consumption and pollution-free advantages have won the majority of the products, thus becoming one of the epoch-making products of display technology, whether in home appliances, information products, or mobile communication products. In the market, with the continuous improvement of quality and the continuous decline of prices, and the integration of the rapid advancement of image signal technology and semiconductor nano-process, LCD display has become the mainstream display product in the market.

Since the liquid crystal panel itself does not have a light-emitting property, it must rely on the backlight module to provide both The uniform light source can achieve the function of its display, and the light can be curved or shielded by the rotation angle of the liquid crystal. Therefore, the performance of the backlight module directly affects the quality of the liquid crystal display, since most of the backlight modules are continuous type The driving method, therefore, unless the power supply is turned off, the backlight module is always in a light-emitting state, and does not change correspondingly with the brightness of the picture, so there is a higher power loss, with the liquid crystal display facing high brightness The high-quality, light-weight, low-cost and environmentally-friendly trend is moving forward. The performance requirements of the backlight module are also synchronized toward high brightness, low power consumption, wide color gamut, light and thin, meticulous, environmentally friendly and low-cost development.

In the operation of the liquid crystal display, the backlight source is generally in a state of full brightness. When the dark portion is displayed, the transmittance of the liquid crystal layer is lowered. Furthermore, since the image quality of the liquid crystal display is also dependent on the contrast of the screen. There is a certain limitation if the contrast of the liquid crystal layer of the liquid crystal display is adjusted to improve the contrast to achieve a clear dark portion. The current liquid crystal display uses a plurality of backlight sources, thereby regulating multiple displays of the liquid crystal display. The area, in order to achieve the purpose of power saving, wherein the local dimming technology of the backlight source means that the plurality of backlight sources of the liquid crystal display are adjusted according to the brightness of the displayed image, instead of being in a full bright state, so the dark portion is displayed. When the brightness of the backlight source is reduced, the power consumption of the entire backlight module can be reduced, and the image quality of the liquid crystal display can be effectively improved, and the Gray Level Luminance Value can be improved.

In the method of driving a backlight source by a local dimming technique, the display panel of the liquid crystal display is divided into a plurality of regions, and the backlight source can increase the brightness of the backlight according to the region corresponding to the brighter image, and reduce the corresponding darkness. The brightness of the backlight of the image area. Therefore, when the number of divided areas of the display panel is increased, the local dimming technology can more precisely control the backlight source to effectively improve the image quality of the liquid crystal display. However, the current liquid crystal display The image local dimming technology used in the backlight module often causes the important image edges of the dark portion to be completely unrepresented, thereby reducing the resolution of the liquid crystal, so that the important image edges of the dark portion are saved, thereby effectively saving power and improving the liquid crystal display. Contrast and resolution are still the issues that LCD developers and researchers need to continuously overcome and solve.

Nowadays, the inventor is in view of the fact that the image local dimming technology of the above-mentioned conventional liquid crystal display cannot effectively display the missing edge information of the dark image due to partial deletion, and thus is a tireless spirit and with its rich professional knowledge and The invention has been developed based on years of practical experience and has been developed.

The main object of the present invention is to provide a high-performance liquid crystal local dimming method and system thereof, and more particularly to a technique and system for locally dimming a backlight source of a liquid crystal screen using image feature values, for storing important image edge information of a dark portion. Effectively achieves an average power saving of 50% and a contrast enhancement of 100 times; in addition, the present invention utilizes local image variability to adjust the relative position of the backlight intensity, and the greater the variability, the stronger the backlight intensity, to preserve image resolution. Degree, when the variability is smaller, the backlight intensity is weakened to save the loss of backlight power; further, the present invention also designs a real-time wafer processing module according to the high-efficiency liquid crystal local dimming method, using common cumulative variability Technology, which significantly reduces the cost of hardware.

In order to achieve the above-mentioned implementation, the present inventors propose a high-performance liquid crystal local dimming method, which at least includes the following steps: First, dividing an image into M × N blocks, wherein each block corresponds to a backlight source. Then, use the Block Mean Variance (BMV) to find the square at the edge, which can be calculated by the following equation: In order to reduce the amount of calculation, both m and n are multiples of 2; the F _jk is the gray level luminance value of the ( j , k )th pixel in the block; finally, the enhancement factor (Ef) is used to obtain The illumination level of the LED backlight unit, which can be calculated by the following equation: Among them, BMV _current is the mean square error of the block in operation, BMV _max is the mean square error of the largest square, taking multiples of 2, and then adjusting with the fixed value α, the illumination of the LED backlight unit can be calculated by the following equation: Block _light = Block _meanlight + Ef ×( Block _{max light} - Block _meanlight ); where Block _meanlight is the average backlight intensity, Block _{max light} is the strongest backlight intensity, the Ef is between 0 and 1, when Ef =1, LED backlight The unit has the highest illumination. When Ef =0, the LED backlight unit is at the average level.

The high-performance liquid crystal local dimming method as described above, wherein the variability of the block is calculated by the common cumulative variability method, and the method includes at least the following steps: First, in the processing of the k-th row, R _n registers The 64 pixels of the first row are accumulated and shifted to the right, and the pixel average (AL _k ) of the kth row is expressed by the following equation: Where F _{( j , k )} is the jth pixel in the kth row; further, the new square mean square error (BMV) can be expressed by the following equation: Wherein, A 1 _{( j )} is the single pixel variability of the jth pixel in the first row, and can be expressed by the following equation: A 1 _{( j )} =| F _{( j ,1)} - AL ₀ |; wherein AL ₀ is The pixel average of line 0, which has been calculated over 64 cycles; then, the jth pixel variability of line 2 to line 4 is defined by A 2 _{( j )} , expressed by the following equation: Among them, the average of the first two lines is used to approximate the block average; after that, with the same concept as above, the variability of the fifth line to the eighth line is defined by A 3 _{( j )} , expressed by the following equation: Among them, since the first 4 rows have been processed, a better approximate average value can be used; finally, according to this procedure, A 4 _{( j )} to A 6 _{( j ) are} sequentially expressed by the following equation: Among them, in the 33rd to 64th behavior example, the first 32 lines have been used to estimate a better local average, which can be completed in real time.

Therefore, the present invention utilizes image feature values to locally dim the backlight source of the liquid crystal display, and is used to store important image edge information of the dark portion, thereby effectively achieving average energy saving. Up to 50% and the contrast is up to 100 times; in addition, the present invention also uses the local image variability to adjust the relative position of the backlight intensity, when the variability is greater, the stronger the backlight intensity, to preserve the resolution of the image, when The smaller the variability is, the backlight intensity is weakened to save the power consumed by the backlight source. Furthermore, the present invention also uses a field programmable gate Array (Field Programmable Gate Array) according to the above-mentioned high-performance liquid crystal local dimming method. The FPGA) chipset implements an instant wafer processing system that uses a common additive variability technique to significantly reduce the cost of hardware expenditures.

Therefore, according to the high-performance liquid crystal local dimming method described above, a high-performance liquid crystal local dimming system can be realized by using a hardware circuit; wherein the high-performance liquid crystal local dimming system comprises an LED backlight unit and a temporary storage And a partial dimming chip unit; the LED backlight unit is composed of a plurality of backlight sources; the temporary register is used for temporarily storing an input image signal to be operated by the system; the local dimming chip unit is composed of a color encoder a horizontal counter, a vertical counter, an input module, a high-performance local dimming module, and an embedded memory; wherein the color encoder converts the three primary color modes (RGB) of the input image signal into Luminance & Chrominance (YUV) information; the horizontal counter confirms the position of the current pixel on the horizontal line by Pixel Clock (P-CK); the vertical counter is input signal by horizontal scanning ( Horizontal Sync (HSYNC for short) calculates the position of the current horizontal line; the input module receives and integrates the color encoder and the horizontal counter described above. And a vertical counter of the input signal is a signal; high performance local dimming module-based high-performance liquid crystal in the local dimming method of calculating the illuminance of the input signal, and outputs various pulse width modulation (Pulse Width Modulation, referred to as PWM) The signal is used to control the operation of the LED backlight unit; wherein the high-performance local dimming module is a tubular system comprising at least one block average module, a block variation module, an enhancement factor module, and a pulse width The modulation module; wherein the block average module is used to calculate the average value of the block; the block variation module is electrically connected to the block average module to calculate the block variability; and the enhancement factor module is electrically connected. The block variation module is used for calculating the enhancement factor; the pulse width modulation module is electrically connected to the enhancement factor module, and the illumination width of the LED backlight unit is obtained according to the pulse width modulation signal; The result of the calculation is temporarily stored in the high-performance local dimming module.

In an embodiment of the invention, the local dimming chip unit can be implemented by an FPGA chipset, and the FPGA is calculated according to a horizontal scanning input signal (HSYNC) and a vertical scanning input signal (Vertical Sync, referred to as VSYNC). The local dimming value of the squares is an image of X × Y pixels, and the size of each local dimming block corresponds to m × n pixels.

In an embodiment of the invention, the high-performance local dimming module uses a Discrete Block-wise Refister to calculate parameters such as block mean, variability, and backlight intensity in parallel to reduce the number of line buffers. The discrete register uses 24 registers to reduce memory requirements. The parameters of each block are calculated by its own register, and 24 registers are used to calculate a row of blocks. The parameters are also parallel. Accumulate, the number of scratchpads increases or decreases with the resolution of the liquid crystal. The higher the resolution, the more registers are stored. Each block is calculated by saving 2 ^m × 2 ⁿ pixels, for example 64 × 64 pixels, to save hardware resources. Displacement methods to achieve low cost.

(1)‧‧‧LED backlight unit

(2) ‧‧‧ register

(3) ‧‧‧Local dimming wafer unit

(31)‧‧‧Color Encoder

(32)‧‧‧Horizontal counter

(33)‧‧‧Vertical counter

(34)‧‧‧ Input Module

(35) ‧‧‧High-performance local dimming module

(351) ‧‧‧ Square Average Module

(352)‧‧‧square variation module

(353)‧‧‧Enhanced Factor Module

(354)‧‧‧ Pulse width modulation module

(36)‧‧‧ embedded memory

(S1)‧‧‧Step one

(S2)‧‧‧Step 2

(S3) ‧ ‧ Step 3

(P1) ‧ ‧ Step 1

(P2) ‧ ‧ step two

(P3)‧‧‧Step three

(P4) ‧‧‧Step four

(P5) ‧ ‧ step five

First: Flow chart of the steps of the high performance liquid crystal local dimming method of the preferred embodiment of the present invention

Second Figure: Flow chart of the steps of the common cumulative variability method of the preferred embodiment of the present invention

Third Figure: Schematic diagram of the common cumulative variability of a preferred embodiment of the present invention

Fourth: a block diagram of a high-performance liquid crystal local dimming system according to a preferred embodiment of the present invention

Figure 5 is a schematic diagram of a discrete register of a preferred embodiment of the present invention

Figure 6 is a schematic diagram of low cost square mean calculation in accordance with a preferred embodiment of the present invention

The purpose of the present invention and the advantages of its circuit design function will be explained in conjunction with the specific embodiments according to the circuit diagram shown in the following drawings, so that the reviewing committee can have a more in-depth and specific understanding of the present invention.

First, referring to the first figure, the flow chart of the high-performance liquid crystal local dimming method of the present invention includes the following steps: Step 1 (S1): splitting an image into M × N squares, wherein Each block corresponds to a backlight source. Generally, if a block contains edge image information, the backlight source will be enhanced so that the block can be clearly seen in the liquid crystal display, and the square at the edge also has high variability. Step 2 (S2): Use the local square mean square error to find the square at the edge. The square mean square error can be calculated by the following equation: In order to reduce the amount of calculation, both m and n are multiples of 2; the gray level brightness value of the ( j , k )th pixel in the F _jk block; and step 3 (S3): using the enhancement factor to obtain the LED The illumination of the backlight unit (1), which can be calculated by the following equation: Among them, BMVV _current is the mean square error of the block in operation, BMV _max is the mean square error of the largest square, taking multiples of 2, and then adjusting with the fixed value α, the illumination of the LED backlight unit (1) can be calculated by the following equation Block _Light = Block _{mean light} + Ef × ( Block _{max light} - Block _meanlight ); where Block _meanlight is the average backlight intensity, Block _{max light} is the strongest backlight intensity, Ef is between 0 and 1, when Ef =1, The LED backlight unit (1) has the maximum illumination. When Ef =0, the LED backlight unit (1) is at the average level.

In addition, please refer to the second to third figures, which is a schematic diagram of the step flow chart and the common accumulated variability of the common additive variability method of the present invention, which can calculate the variability of the block in real time by using the common cumulative variability method. The steps include: Step 1 (P1): In the processing of the kth row, 64 pixels of the first row of the R _n registers are accumulated and shifted right, and the pixel average of the kth row is below (AL _k ) The column equation represents: Where F _{( j , k )} is the jth pixel in the kth row; step 2 (P2): the new square mean square error (BMV) is expressed by the following equation: Where A 1 _{( j )} is a single pixel variation of the jth pixel in the first row, expressed by the following equation: A 1 _{( j )} =| F _{( j ,1)} - AL ₀ |; where AL ₀ is the first The pixel average of 0 lines, which has been calculated over 64 cycles; Step 3 (P3): Define the jth pixel variability from line 2 to line 4 with A 2 _{( j )} , expressed by the following equation: The average of the first two rows is used to approximate the block average; step four (P4): with the same concept as above, the variability of the fifth row to the eighth row is defined by A 3 _{( j )} , expressed by the following equation: Among them, since the first 4 rows have been processed, a better approximate average value can be used; and step 5 (P5): According to this procedure, A 4 _{( j )} to A 6 _{( j ) are} sequentially expressed by the following equation: Among them, in the 33rd to 64th behavior example, the first 32 lines have been used to estimate a better local average, which can be completed in real time.

The high-performance liquid crystal local dimming method and the common additive variability method may be performed by a hardware system; accordingly, the high-performance liquid crystal according to the preferred embodiment of the present invention is illustrated in the fourth figure. The configuration diagram of the local dimming system includes: an LED backlight unit (1), which is composed of a plurality of backlight sources; and a temporary register (2) for temporarily storing an input image signal to be operated by the system; And a partial dimming chip unit (3), comprising a color encoder (31), a horizontal counter (32), a vertical counter (33), an input module (34), and a high-performance local dimming mode The group (35) and an embedded memory (36); the color encoder (31) converts the three primary color modes (RGB) of the input image signal into brightness and chrominance (YUV) information; 32) confirming the position of the current pixel at the horizontal line by the pixel clock; the vertical counter (33) calculates the position of the current horizontal line by the horizontal scanning input signal; and the input module (34) receives and integrates the above color encoder (31) ), horizontal counter (32), and vertical meter The signal of the digital device (33) is an input signal; the high-performance local dimming module (35) calculates the illumination of the input signal by a high-performance liquid crystal local dimming method, and outputs various pulse width modulation (PWM). a signal to control operation of the LED backlight unit (1), wherein the high-performance local dimming module (35) is a tubular system to The method includes a block average module (351), a block variation module (352), an enhancement factor module (353), and a pulse width modulation module (354); wherein the block average module (351) ) is used to calculate the average value of the block; the block variation module (352) is an electrical connection block average module (351) for calculating the block variability; and the enhancement factor module (353) is electrically connected to the block variation. a module (352) for calculating an enhancement factor; the pulse width modulation module (354) is electrically connected to the enhancement factor module (353), and the pulse width modulation signal is obtained to obtain an LED backlight unit (1) Illumination; embedded memory (36) is used to temporarily store the results of the high-performance local dimming module (35).

In addition, the local dimming chip unit (3) can be implemented by a field editable logic gate array (FPGA) chip set, which calculates the local dimming value of each block according to the horizontal scanning input signal and the vertical scanning input signal. In the image of X × Y pixels, the size of each local dimming block corresponds to m × n pixels.

Furthermore, please refer to the fifth figure, which is a schematic diagram of a discrete register according to a preferred embodiment of the present invention. The high-performance local dimming module (35) uses a discrete register to calculate the mean and variability of the block in parallel. Parameters such as backlight intensity reduce the number of line buffers. The discrete register uses 24 registers (R1~R24) to reduce memory requirements. The parameters of each block are calculated by its own register. A register is used to calculate a row of blocks whose parameters, block mean, variability, and backlight intensity are processed in parallel. Each block calculation is based on 2 multiples, with 2 ^m × 2 ⁿ pixels, such as 64 × 64 pixels, to save Hardware resources, using the right displacement method to achieve low cost.

Please refer to the sixth figure, which is a schematic diagram of low-cost block mean calculation according to a preferred embodiment of the present invention. The operation steps are first in a block, and 64 pixels of each line are firstly Accumulated in a horizontal register (Horizontal Register), in order to reduce the word length of the scratchpad (Word Length), the horizontal register is shifted to the right by 6 bits (Bits), and then accumulated in the vertical register ( Vertical Register), the result of accumulating 64 lines in the vertical register and then shifting 6 bits to the right, which is a low-cost block average calculation method. The horizontal and vertical registers only need 14 bits, so The sum of the memory capacities is 2 × 14 × 24 = 672 bits, which is found in the table, which can greatly reduce the number of line buffers.

It can be seen from the above description of the high-performance liquid crystal local dimming method and its system that the present invention has the following advantages:

1. The high-performance liquid crystal local dimming method and system thereof of the present invention locally dims the backlight source of the liquid crystal display by image feature values, and is used for storing important image edge information of the dark portion, effectively achieving an average power saving of 50%. With a lifting contrast of up to 100 times.

2. The high-performance liquid crystal local dimming method and system thereof of the present invention adjust the relative position of the backlight intensity by local image variability. When the variability is larger, the backlight intensity is stronger, and the image resolution is preserved when the variation The smaller the degree, the weaker the backlight, to save the loss of backlight power.

3. The high-performance liquid crystal local dimming method and system thereof of the present invention are efficient The liquid crystal local dimming method realizes the instant wafer processing system with the FPGA chipset, and adopts the common accumulation variability technology, which can greatly reduce the cost of hardware expenditure.

In summary, the high-performance liquid crystal local dimming method and system thereof of the present invention can achieve the intended use efficiency by the above-disclosed embodiments, and the present invention has not been disclosed before the application, and has been completely completed. Meet the requirements and requirements of the Patent Law.爰Issuing an application for a patent for invention in accordance with the law, and asking for a review, and granting a patent, is truly sensible.

The illustrations and descriptions of the present invention are merely preferred embodiments of the present invention, and are not intended to limit the scope of the present invention; those skilled in the art, which are characterized by the scope of the present invention, Equivalent variations or modifications are considered to be within the scope of the design of the invention.

(S1)‧‧‧Step one

(S2)‧‧‧Step 2

(S3) ‧ ‧ Step 3

Claims (8)

A high-performance liquid crystal local dimming method for improving the information of the edge of the dark portion image includes the following steps: Step 1: dividing an image into M × N squares, each of which corresponds to a backlight source; Step 2: using a local portion The square mean square error finds the square at the edge, which is calculated by the following equation: In order to reduce the amount of calculation, both m and n are multiples of 2; the gray level brightness value of the ( j , k )th pixel in the F _jk block; and step 3: using the enhancement factor to obtain the illumination of the LED , the enhancement factor is calculated by the following equation: Where BMV _current is the mean square error of the block in operation, BMV _max is the mean square error of the largest square, taking a multiple of 2, and then adjusting with the fixed value α, the LED illumination is calculated by the following equation: Block _light = Block _meanlight + Ef ×( Block _{max light} - Block _meanlight ); where Block _meanlight is the average backlight intensity, Block _{max light} is the strongest backlight intensity, Ef is between 0 and 1. When Ef =1, the LED backlight unit has the largest Illumination, when Ef =0, the LED backlight unit is at the level of the average. For example, in the high-performance local dimming method described in claim 1, wherein the variability of the block is calculated in real time by the common cumulative variability method, and the steps include: Step 1: In the processing of the kth line, R The 64 pixels of the first row of the _n registers are accumulated and shifted to the right, and the pixel average (AL _k ) of the kth row is expressed by the following equation: Where F _{( j , k )} is the jth pixel in the kth row; Step 2: The new square mean square error is expressed by the following equation: Where A 1 _{( j )} is the single pixel variability of the jth pixel in the first row, expressed by the following equation: A 1 _{( j )} =| F _{( j ,1)} - AL ₀ |; where AL ₀ is The pixel average of line 0, which has been calculated over 64 cycles; step three: define the jth pixel variability of line 2 to line 4 with A 2 _{( j )} , expressed by the following equation: The average of the first two rows is used to approximate the block average; step four: according to the above concept, the variability of the fifth row to the eighth row is defined by A 3 _{( j )} , expressed by the following equation: Wherein, since the first 4 rows have been processed, a better approximate average value can be used; and step 5: according to this procedure, A 4 _{( j )} to A 6 _{( j ) are} sequentially expressed by the following equation: Among them, in the 33rd to 64th behavior example, the first 32 lines have been used to estimate a better local average to complete the instant calculation. A high-performance liquid crystal local dimming system is characterized by high-performance liquid crystal local dimming method, at least comprising: an LED backlight unit, which is composed of a plurality of backlight sources; a temporary register, temporarily storing an input The image signal is to be operated by the system; and a partial dimming chip unit includes a color encoder, a horizontal counter, a vertical counter, an input module, a high-performance local dimming module, and an embedded memory. The color encoder converts the input image signal three primary color modes (RGB) into brightness and chrominance (YUV) information; the horizontal counter confirms that the current pixel is at a horizontal line by the pixel clock; the vertical counter, Calculating the position of the current horizontal line by horizontally scanning the input signal; the input module receives and integrates the color encoder, the horizontal counter, and the signal of the vertical counter as an input signal; the high-performance local dimming module The high-performance liquid crystal local dimming method is used to calculate the illumination of the input signal, and output various pulse width modulation signals. To control the LED backlight unit, wherein the high performance local portion The dimming module is a tubular system comprising at least a block average module, a block variation module, an enhancement factor module, and a pulse width modulation module; wherein the block average module calculates the average of the blocks The block variation module is electrically connected to the block average module to calculate a block variability; the enhancement factor module is electrically connected to the block variation module to calculate an enhancement factor; the pulse width modulation The module is electrically connected to the enhancement factor module, and adjusts the illumination of the LED backlight unit according to the pulse width modulation signal; the embedded memory stores the calculated result of the high performance local dimming module. The high performance liquid crystal local dimming system of claim 3, wherein the local dimming chip unit is implemented by a field editable logic gate array (FPGA) chipset. The high-performance liquid crystal local dimming system according to claim 4, wherein the FPGA calculates a local dimming value of each block according to a horizontal scanning input signal and a vertical scanning input signal, and an image of X × Y pixels. The size of each local dimming block corresponds to m × n pixels. The high-performance liquid crystal local dimming system according to claim 3, wherein the high-performance local dimming module uses a discrete register to calculate parameters such as mean, variability, and backlight intensity in parallel, and reduces the line. The number of buffers. The high-performance liquid crystal local dimming system according to claim 5, wherein the discrete register uses 24 registers to reduce memory requirements, and each block parameter is calculated by its own register. Using 24 registers to calculate a row of blocks, the parameters are also added in parallel, the number of registers increases or decreases with the resolution of the liquid crystal, and the larger the resolution, the more registers. The high-performance liquid crystal local dimming system according to claim 7, wherein each block is calculated to save hardware resources by 2 ^m × 2 ⁿ pixels, and the right displacement method is used to achieve low cost.