CN115641822A - Liquid crystal display panel and display device - Google Patents

Abstract

The application discloses a liquid crystal panel and a display device, wherein the liquid crystal panel comprises a liquid crystal layer and a driving circuit, the driving circuit generates driving voltage based on a pulse width modulation signal, and the driving voltage is loaded on two sides of the liquid crystal layer so as to drive the liquid crystal panel to display images; the pulse width modulation signal generates a driving voltage according to a first voltage and a second voltage, the difference value between the first voltage and the second voltage is smaller than the maximum voltage of the liquid crystal panel, and the first voltage and the second voltage are both larger than zero and smaller than the maximum voltage; the driving voltage corresponds to an equivalent driving voltage value. According to the liquid crystal display panel, modulation is carried out in a pulse width modulation signal mode, the range of the interval covered by the first voltage and the range covered by the second voltage are adjusted, the difference value of the first voltage and the second voltage is smaller than the maximum voltage of the liquid crystal display panel, refinement of time division and accuracy of voltage drive liquid crystal are combined, modulation precision is improved, and the display gray scale effect of the liquid crystal display panel is further improved.

Description

Liquid crystal display panel and display device

Technical Field

The present disclosure relates to liquid crystal display driving, and more particularly, to a liquid crystal display panel and a display device.

Background

LCoS (liquid Crystal on Silicon) is a Silicon-based micro-display technology combining a CMOS integrated circuit design process and a liquid Crystal packaging technology, wherein gray scale precision is one of key factors of the display performance of an LCoS chip. In the prior art, LCoS projection is connected with an image signal with 8-bit gray scale, and only 5-6-bit gray scale can be displayed.

The driving mode of the LCoS comprises digital driving and analog driving. The analog driving uses a Dynamic Random Access Memory (DRAM) to realize different gray scale display of the pixels, an input display signal needs to be converted into an analog voltage signal through a digital-to-analog converter, and the voltage difference between the signal and a common electrode signal is the voltage at two ends of the pixel. The analog drive can realize the modulation of the pixel voltage by controlling the output voltage of the digital-to-analog converter, thereby realizing the gray scale display control. Specifically, the analog driving is divided by a driving voltage to realize gray scale display control. The analog driving limits the voltage division precision, and the high-precision control cannot be achieved, so that the display effect of the LCoS is affected.

Digital driving generally utilizes Static Random-Access Memory (SRAM) to realize different gray levels of pixels. The digital driving controls different gray levels by modulating the on-time of the pixel switches, i.e. a Pulse Width Modulation (PWM) control method. In the prior art, the driving voltage of the LCoS is 0-5V, and the PWM divides the 0-5V according to the equal step length to realize the gray scale display control. The influence of the front end and the tail end of the driving voltage on the response of the liquid crystal is very small, so that the division of the PWM at the front end and the tail end of the driving voltage is invalid, and the actually realized visual gray scale digit is obviously lower than the designed gray scale digit.

Disclosure of Invention

In order to improve the actual visual display gray scale effect of the liquid crystal panel, the application discloses the liquid crystal panel, which comprises a liquid crystal layer and a driving circuit, wherein the driving circuit generates driving voltage based on a pulse width modulation signal, and the driving voltage is loaded on two sides of the liquid crystal layer so as to drive the liquid crystal panel to display images; the pulse width modulation signal generates a driving voltage according to a first voltage and a second voltage, the first voltage is smaller than the second voltage, the difference value between the first voltage and the second voltage is smaller than the maximum voltage of the liquid crystal panel, and the first voltage and the second voltage are both larger than zero and smaller than the maximum voltage; the driving voltage corresponds to an equivalent driving voltage value for any frame of image data.

The beneficial effect of this application is: different from the prior art, the liquid crystal display panel is modulated in a pulse width modulation signal mode, the voltage range covered by the first voltage and the second voltage is firstly reduced, the difference value between the first voltage and the second voltage is smaller than the maximum voltage of the liquid crystal panel, the response of the liquid crystal is more accurately matched with the voltages loaded on two sides of the liquid crystal, the interval with unobvious liquid crystal response is avoided, the corresponding relation between the more refined voltage and the gray scale is obtained in a pulse width modulation time division mode, the refinement of time division and the precision of voltage driving liquid crystal are combined, the modulation precision is improved, and the gray scale display effect of the liquid crystal panel is further improved.

In one embodiment, the equivalent driving voltage value is equal to a time-weighted average of the first voltage and the second voltage during any one frame of image.

In one embodiment, the liquid crystal panel is used for displaying an N-bit binary image, and the first voltage to the second voltage are divided into 2 ^N The voltage difference of the equivalent driving voltage values of two adjacent stages is equal.

In one embodiment, the first voltage is a minimum response voltage of the liquid crystal panel, and the second voltage is a maximum response voltage of the liquid crystal panel.

In one embodiment, the difference between the first voltage and the zero voltage respectively affects the transmittance of the liquid crystal panel is less than a first preset range; the difference between the second voltage and the maximum voltage respectively influences the transmissivity of the liquid crystal panel is smaller than a second preset range.

In one embodiment, when the equivalent driving voltage value is the first voltage, the relative transmittance of the liquid crystal panel is 100%, the driving voltage is the second voltage, and the relative transmittance of the liquid crystal panel is 0%; or, when the equivalent driving voltage value is the first voltage, the relative transmittance of the liquid crystal panel is 0%, the driving voltage is the second voltage, and the relative transmittance of the liquid crystal panel is 100%.

In one embodiment, the first voltage is not less than 1.6V and the second voltage is not greater than 4.3V.

The present application also includes a display device including the liquid crystal panel in any of the above embodiments, and further including a light source that emits illumination light, and the liquid crystal panel modulates the illumination light emitted by the light source to generate image light.

In one embodiment, the display device further comprises a control system for synchronously controlling the liquid crystal panel and the light source according to the image data, and when the control system controls the output power of the illumination light to increase/decrease, the control system controls the pulse width modulation signal of the liquid crystal panel so that the equivalent driving voltage value decreases/increases accordingly.

In one embodiment, the display device further comprises a memory for storing a look-up table establishing a relationship between the value of the equivalent driving voltage and the waveform of the pulse width modulated signal.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a graph of electro-optic characteristics of a prior art display panel;

FIG. 2 is a schematic structural diagram of an embodiment of a liquid crystal panel of the present application;

FIG. 3 is a schematic diagram of a pulse width modulated signal according to the present application;

fig. 4 is an electro-optical characteristic curve of the liquid crystal panel of the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solutions of the present application, the liquid crystal panel and the display device provided in the present application will be described in further detail below with reference to the accompanying drawings and the detailed description. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first", "second", etc. in this application are used to distinguish between different objects and not to describe a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

In the field of displays, LCoS (liquid Crystal on Silicon) micro display chips are often used. The LCoS is a silicon-based micro-display technology combining a CMOS integrated circuit design process and a liquid crystal packaging technology, and the resolution, the filling factor, the reflectivity, the frame rate, the power consumption, the display area, the gray scale precision and the linearity are key performances of an LCoS chip. The drive mode of the LCoS pixel comprises an analog drive mode and a digital drive mode. The LCoS chip realized by the analog driving mode has the advantages of relatively simple algorithm, stable gray scale, low power consumption and the like, but the control precision of the analog driving mode is limited, and the display effect of the LCoS chip is influenced. And the digital driving mode can provide high-precision gray scale control and improve the display effect of the LCoS.

In particular, in describing digital images, the color bit depth of an image is also referred to as the grayscale resolution, which refers to the number of grayscale gradients used in preparing the image for display. A digital image with a higher grayscale resolution is composed of more grayscale gradients and is displayed with a greater bit depth than a digital image with a lower grayscale resolution.

The LCoS chip controls the phase change of the liquid crystal by the electric field voltage, and the measured curve is an E-O curve (electro-optical curves), i.e. an electro-optical response curve, as shown in fig. 1, where fig. 1 is an electro-optical characteristic curve of a display panel in the prior art. Specifically, the relative transmittance is a proportion of light emitted from the liquid crystal panel passing through the polarization selector in the downstream optical path, and is taken as 100% when the actual transmittance is the maximum.

As shown in fig. 1, in this embodiment, the relative transmittance of the liquid crystal panel increases as the voltage applied to the liquid crystal panel increases; when the applied voltage of the liquid crystal panel is minimum, the relative transmissivity of the liquid crystal panel is maximum; when the applied voltage of the liquid crystal panel is maximum, the relative transmittance of the liquid crystal panel is minimum. It will be appreciated that if the polarization selector is configured to switch the characteristics of the transmitted and reflected S light and the P light, the transmission may be the smallest when the applied voltage is the smallest and the largest when the applied voltage is the largest, and this application is only illustrative in one way for ease of illustration and to avoid confusion.

Digital images are usually realized by PWM (Pulse Width Modulation), which requires a fixed bit depth. Although the color bit depth and the E-O bit depth are defined independently for separate matrices, they may be correlated by a lookup table to map the color gray scale to the E-O gray scale. The largest resource consumption of LCoS is the PWM operation of each pixel cell. The 8-bit E-O bit depth has reached the limits and acceptable power consumption of mainstream CMOS processes. Therefore, it is very difficult to further improve the grayscale resolution by increasing the number of bits.

The application provides a liquid crystal display panel, through the operating voltage and the cut-off voltage of adjusting pulse width modulation signal, reduce the scope of electric field voltage to increase the actual display gray scale that liquid crystal display panel shows the image.

Referring to fig. 2, fig. 2 is a schematic structural diagram of an embodiment of a liquid crystal panel according to the present application, and as shown in fig. 2, a liquid crystal panel 10 includes a liquid crystal layer 11 and a driving circuit 12. The driving circuit 12 generates a driving voltage based on the pwm signal, and the driving voltage is applied to two sides of the liquid crystal layer 11 to drive the liquid crystal panel 10 to display an image.

The pulse width modulation is a digital control mode, and the bias of a transistor base or an MOS tube grid is modulated according to the change of corresponding load to change the conduction time of the transistor or the MOS tube, so that the change of the output of the switching voltage-stabilized power supply is realized. This way the output voltage of the power supply can be kept constant when the operating conditions change, which is a very effective technique for controlling an analog circuit by means of the digital signal of the microprocessor.

The pulse width modulated signal is passed through the use of a high resolution counter and the duty cycle of the square wave is modulated to encode the level of a particular signal. The PWM signal is still digital because at any given time, the full magnitude dc supply is either completely ON or completely OFF. The voltage or current source is applied to the analog load in a repetitive pulse train of ON (ON) or OFF (OFF). The on-time is when the dc supply is applied to the load and the off-time is when the supply is disconnected.

Referring further to fig. 3, fig. 3 is a schematic diagram of a pwm signal according to the present application. As shown in fig. 3, the pwm signal of the present embodiment generates the driving voltage according to the first voltage and the second voltage, and uses the first voltage V0 as the operating state of the pwm signal, i.e. the state where the voltage of the pwm signal is full (ON); the second voltage V1 is used as an OFF state of the pwm signal, that is, the voltage of the pwm signal is in an OFF state, wherein the first voltage V0 is less than the second voltage V1, and both the first voltage V0 and the second voltage V1 are greater than zero and less than the maximum voltage of the liquid crystal panel 10.

Specifically, the driving circuit 12 is configured to adjust a difference between a first voltage V0 and a second voltage V1 of the pwm signal, where the adjusted difference is smaller than a maximum voltage of the liquid crystal panel 10, so as to increase a gray scale of an image displayed by the liquid crystal panel 10.

The maximum voltage of the liquid crystal panel 10 is limited by the semiconductor transistors in the liquid crystal panel 10, and the maximum voltage is the highest voltage that the transistors can support, and in a general wafer foundry, the highest voltage that the semiconductor transistors in the liquid crystal panel 10 can support is 5V, and 0V and 5V are respectively used as the operating voltage and the cut-off voltage of the pwm signal.

The direct use of 0V and 5V as operating and cut-off voltages has a number of drawbacks. First, the voltage difference between the two is large, and in digital modulation, the voltage difference actually applied to both ends of the liquid crystal pixel at any time is only two values, i.e., 0 or 5, so that the adjacent liquid crystal pixels are also affected by an excessive voltage difference, pixel crosstalk occurs, an image cannot be correctly displayed, and the contrast is reduced. Secondly, in a section of interval where the voltage difference is close to 0V or 5V, the liquid crystal response is not obvious, which makes it difficult to distinguish the light and shade difference between the smaller gray values or between the larger gray values, for example, pixels with 1 gray and 2 gray should have a 2-fold difference in brightness perception, but the actual gray level is only equivalent to 5, 6 bits of data because the human eye cannot distinguish due to the unobvious liquid crystal response.

Typically, when the pwm signal is applied by using 0V and 5V as the operating voltage and the cut-off voltage of the pwm signal, the lcd panel can only display 5-6bit gray scales when receiving the 8bit gray scale image signal, so that the image display effect is insufficient.

Therefore, in the embodiment of the present invention, the first voltage V0 is selected as the minimum response voltage of the liquid crystal panel, and the second voltage V1 is selected as the maximum response voltage of the liquid crystal panel.

In particular, when the voltage is less than the minimum response voltage or greater than the maximum response voltage, the influence of the liquid crystal on the transmittance is insignificant. The difference between the first voltage V0 and the zero voltage (namely 0V) on the influence of the transmissivity of the liquid crystal panel is smaller than a first preset range; the difference between the second voltage V1 and the maximum voltage (i.e., 5V) respectively affects the transmittance of the liquid crystal panel is smaller than a second preset range. The first preset range may be, for example, not more than 0.4%. The second preset range may be, for example, not more than 0.4%.

As can be seen from fig. 1, when the applied voltage of the liquid crystal panel is increased from 0V to 1.6V, the relative transmittance of the liquid crystal panel is substantially unchanged and maintained at about 100%; when the applied voltage of the liquid crystal panel is increased from 4.3V to 5V, the relative transmittance of the liquid crystal panel is basically unchanged and is maintained at about 0%. That is, the low voltage region from 0V to 1.6V and the high voltage region from 4.3V to 5V have no or little influence on the phase transition of the liquid crystal in the liquid crystal panel, so the present embodiment specifically uses 1.6V and 4.3V as the operating voltage and the cut-off voltage of the pwm signal, i.e., the first voltage V0 and the second voltage V1, respectively. In other embodiments of the present invention, the first voltage is not less than 1.6V and the second voltage is not more than 4.3V in order to avoid voltage ranges where the response of the liquid crystal is insignificant.

As shown in fig. 3, the pwm signal has a plurality of periods T, wherein each period T corresponds to one image frame, and the driving circuit 12 modulates the plurality of consecutive image frames by signal modulation of a plurality of consecutive periods T. The plurality of continuously changing image frames form an image to enable display of the image.

Each period T is divided into a plurality of preset time periods Δ T, and the duty ratio of the pulse width modulation signal is the ratio of the total time of the second voltage V1 to the time of the period T in each period T.

Alternatively, the first voltage V0 and the second voltage V1 may be continuously or intermittently changed in each period T, and the pulse signals of the first voltage V0 and the second voltage V1 in each period T may be single or multiple.

As shown in fig. 3, in the first period T, the first voltage V0 and the second voltage V1 both continuously change, and at this time, ONE period T only includes ONE pulse signal of the first voltage V0 and ONE pulse signal of the second voltage V1, which is also referred to as an ON-ONE-OFF mode. Since the liquid crystal has a certain response time, which may cause the actual relative transmittance change caused by the pulse width modulation to have a longer rising edge or falling edge, the ONE-ON-ONE-OFF mode may obtain a more precise modulation effect by reducing the number of rising and falling times of the signal waveform. Therefore, it is preferable that the ONE-ON-ONE-OFF mode is selected to modulate the liquid crystal during any period T.

In the second period T, the second voltage V1 changes intermittently, and the first voltage V0 changes continuously, and at this time, one period T includes a pulse signal of the first voltage V0 and two pulse signals of the second voltage V1.

In the third period T, the first voltage V0 and the second voltage V1 both vary intermittently, and at this time, one period T includes two pulse signals of the first voltage V0 and three pulse signals of the second voltage V1.

Optionally, the application does not limit the number of the pulse signals of the first voltage V0 and the second voltage V1 in a single period, and fig. 3 is only a schematic diagram of the pwm signal.

The liquid crystal panel 10 of the present embodiment is used to display N-bit binary images, and each period T is divided into 2 ^N A preset time period deltat. The liquid crystal panel 10 has 2 ^N A gray scale for displaying the binary image of N bits. In the nth gray scale of the liquid crystal panel 10, the total time of the second voltage V1 is n preset time periods Δ t, n is less than 2 ^N Is an integer of (2). Specifically, n =0, 1, 2 … … 2 ^N -1. Where N may be 8, 10, or 12, etc., i.e., the binary image may be an RGB image of 8bit depth, 10bit depth, or 12 bit depth. Wherein the first voltage V0 and the second voltage V1 are divided into 2 ^N And the voltage difference between two adjacent stages is equal.

Specifically, the number of the preset time periods Δ T occupied by the second voltages V1 in each period T is different, and the corresponding gray scales are also different. Meanwhile, the number of the preset time period Δ T occupied by the second voltage V1 in each period T affects the total time of the second voltage V1, and the duty ratio of the pwm signal is proportional to the total time of the second voltage V1 adjusted in each period T, so that the gray scale is proportional to the duty ratio.

The number of the preset time periods delta t is in direct proportion to the gray scale, and the gray scale is increased by one step when the preset time period delta t is increased. When the number of the adjusted second voltage V1 in the preset time period delta T in each period T is zero, the adjusted second voltage corresponds to the lowest gray scale; the number of the preset time period delta T occupied by the adjusted second voltage V1 in each period T is 2 ^N And corresponds to the highest gray level.

The driving voltages all correspond to an equivalent driving voltage value, the driving circuit 12 calculates the equivalent driving voltage value according to the duty ratio, the difference value and the first voltage V0, the equivalent driving voltage value is equal to a time weighted average value of the first voltage V0 and the second voltage V1, and the specific calculation formula is as follows:

V _PWM ＝D*(V1-V0)+V0

wherein, V _PWM D is a duty ratio, and the equivalent driving voltage value is greater than or equal to the first voltage V0 and less than or equal to the second voltage V1.

The electro-optical characteristic curve of the liquid crystal panel of this embodiment can be obtained by performing data fitting on the calculated driving voltage, as shown in fig. 4, fig. 4 is the electro-optical characteristic curve of the liquid crystal panel of this application, wherein the "driving voltage" on the horizontal axis corresponds to the equivalent driving voltage value.

From the above calculation formula, it can be known that the driving voltage and the duty ratio are in a direct proportion relationship, and the gray scale and the duty ratio are in a direct proportion, it is inferred that the driving voltage and the gray scale are in a direct proportion, and the voltage difference between the driving voltage corresponding to the nth gray scale and the driving voltage corresponding to the (n + 1) th gray scale is a constant value.

Specifically, the driving voltage corresponding to the highest gray level is equal to the second voltage V1, the driving voltage corresponding to the lowest gray level is equal to the first voltage V0, and the voltage difference between the driving voltage corresponding to the nth gray level and the driving voltage corresponding to the (n + 1) th gray level is equal to the adjusted difference between the second voltage V1 and the first voltage V0 divided by 2 ^N 。

This embodiment is further illustrated by taking an 8-bit binary image as an example, i.e., N is equal to 8,2 ^N Equal to 256. When the liquid crystal panel 10 is used for displaying an 8-bit binary image, the liquid crystal panel 10 is correspondingly provided with 256 gray scales, wherein the lowest gray scale is V (0), and the driving voltage is the first voltage V0; the highest level gray scale is V (255), and the driving voltage is the second voltage V1. The first voltage V0 is the maximum response voltage of the liquid crystal panel 10, and the second voltage V1 is the minimum response voltage of the liquid crystal panel 10.

As can be seen from fig. 4, in this embodiment, the relative transmittance of the liquid crystal panel 10 is inversely related to the equivalent driving voltage value, and the relative transmittance of the liquid crystal panel 10 decreases as the driving voltage increases. When the driving voltage (equivalent driving voltage value) is the first voltage V0, the relative transmittance of the liquid crystal panel 10 is 100%; when the driving voltage (equivalent driving voltage value) is the second voltage V1, the relative transmittance of the liquid crystal panel 10 is 0%.

It is understood that the relative transmittance is related to the polarization splitting plate disposed at the exit end of the liquid crystal panel 10 and whether a wave plate is disposed in the optical path system. Taking LCD as an example, if the transmission/reflection characteristics of the polarization beam splitter at the exit end to S light and P light are changed, the curve is reversed, so that 100% is exchanged with 0%. Taking LCoS as an example, if the 1/4 wave plate near the LCoS liquid crystal layer is increased or decreased, 100% will also be swapped with 0%.

The present disclosure is only exemplified by one of the cases, and mainly aims to illustrate that the first voltage V0 and the second voltage V1 respectively correspond to one of 100% relative transmittance and 0% relative transmittance.

Unlike the prior art in which 0V and 5V are used as the operating voltage and the cut-off voltage of the pwm signal, the present embodiment adjusts the first voltage V0 to 1.6V and the second voltage V1 to 4.3V, so as to reduce the variation range of the driving voltage. Comparing the prior art with the present embodiment, the present embodiment adjusts the first voltage V0 and the second voltage V1 of the pwm signal, so that the difference between the first voltage V0 and the second voltage V1 is smaller than the maximum voltage of the liquid crystal panel 10, i.e. smaller than 5V.

Under the condition that the display gray scale levels are the same, the voltage difference between the driving voltages corresponding to the adjacent two levels of gray scales is reduced compared with the prior art, so that the liquid crystal panel 10 can change the display gray scale with a smaller voltage change value, the response speed of the liquid crystal panel 10 is effectively improved, the gray scale resolving capability of the liquid crystal panel 10 is improved, the display gray scale effect of 1-2 bits is improved on the basis of the prior art by the liquid crystal panel 10, the display gray scale effect of the liquid crystal panel 10 is further improved, and the gray scale of the image displayed by the liquid crystal panel 10 is increased.

The application also provides a display device, which comprises a light source and a liquid crystal panel. The liquid crystal panel has already been described in the above embodiments, and is not described again here. The light source is used for emitting illumination light, the illumination light is incident to the liquid crystal panel, and the liquid crystal panel modulates the illumination light emitted by the light source, so that image light is explained.

Further, when the display device is a projection device, the display device further comprises a projection lens for enlarging and projecting the image light emitted by the liquid crystal panel to a predetermined position to form a display image. When the display device is an AR or VR device, the display device further comprises an optical coupler for optically coupling and imaging the image emitted by the liquid crystal panel to human eyes.

In the invention, the liquid crystal panel is modulated by adopting a digital pulse width modulation method, so that the distribution of equivalent driving voltage values is very uniform, and the numerical value mapping is particularly convenient. When the technical scheme is applied to a Global Dimming (Global Dimming) or Global Brightening (Global Dimming) application scene, the change of the equivalent driving voltage value can be simple and convenient when the brightness of the light source is changed.

Specifically, in an embodiment of the present invention, the display device further includes a control system for synchronously controlling the liquid crystal panel and the light source according to the image data, and when the control system controls the output power of the illumination light to increase/decrease, the control system controls the pulse width modulation signal of the liquid crystal panel so that the equivalent driving voltage value decreases/increases accordingly.

The control of the pulse width modulation signal may be implemented by means of a look-up table (look-up table). Specifically, in this embodiment, the display device further includes a memory for storing a lookup table that establishes a relationship between the equivalent driving voltage value and the waveform of the pulse width modulation signal.

For example, when the overall image is darker, the global dimming procedure is started to reduce the brightness L of the conventional light source to α L, and then to correctly display the image, the gray scale value of the image needs to be increased as a whole, the duty ratio of the second voltage V1 is increased from D to β D, so that the equivalent driving voltage value changes correspondingly, and then the pulse width modulation signal waveform for driving each pixel is obtained through the lookup table and is output to the two ends of the liquid crystal pixel. In the digital modulation display mode of the invention, the feeling of human eyes to the brightness is just obtained by the time integration of the brightness of each frame, and the time duty ratio of the first voltage V0 and the second voltage V1 of the equivalent driving voltage value is just corresponding to the feeling, so that the more convenient matching can be realized.

The above embodiments are merely examples, and not intended to limit the scope of the present application, and all modifications, equivalents, and flow charts using the contents of the specification and drawings of the present application, or those directly or indirectly applied to other related arts, are included in the scope of the present application.

Claims (10)

1. The liquid crystal panel is characterized by comprising a liquid crystal layer and a driving circuit, wherein the driving circuit generates driving voltage based on a pulse width modulation signal, and the driving voltage is loaded on two sides of the liquid crystal layer so as to drive the liquid crystal panel to display images; the driving voltage is generated by the pulse width modulation signal according to a first voltage and a second voltage, the first voltage is smaller than the second voltage, the difference value between the first voltage and the second voltage is smaller than the maximum voltage of the liquid crystal panel, and the first voltage and the second voltage are both larger than zero and smaller than the maximum voltage; the driving voltages all correspond to an equivalent driving voltage value.

2. The liquid crystal panel according to claim 1, wherein the equivalent driving voltage value is equal to a time-weighted average of the first voltage and the second voltage during any one frame image.

3. The liquid crystal panel according to claim 2, wherein the liquid crystal panel is configured to display an N-bit binary image, and the first voltage to the second voltage are divided into 2 ^N The voltage difference of the equivalent driving voltage values of two adjacent stages is equal.

4. The liquid crystal panel according to any one of claims 1 to 3, wherein the first voltage is a minimum response voltage of the liquid crystal panel, and wherein the second voltage is a maximum response voltage of the liquid crystal panel.

5. The liquid crystal panel according to claim 4, wherein the difference between the first voltage and the zero voltage respectively has an effect on the transmittance of the liquid crystal panel is smaller than a first preset range; the difference between the influence of the second voltage and the influence of the maximum voltage on the transmissivity of the liquid crystal panel are smaller than a second preset range.

6. The liquid crystal panel according to claim 5, wherein when the equivalent driving voltage value is the first voltage, the relative transmittance of the liquid crystal panel is 100%, the driving voltage is the second voltage, and the relative transmittance of the liquid crystal panel is 0%; alternatively, the first and second electrodes may be,

when the equivalent driving voltage value is the first voltage, the relative transmittance of the liquid crystal panel is 0%, the driving voltage is the second voltage, and the relative transmittance of the liquid crystal panel is 100%.

7. The liquid crystal panel according to any one of claims 1 to 3, wherein the first voltage is not less than 1.6V, and wherein the second voltage is not more than 4.3V.

8. A display device comprising the liquid crystal panel according to any one of claims 1 to 7, and further comprising a light source that emits illumination light, the liquid crystal panel modulating the illumination light emitted by the light source to generate image light.

9. The display device according to claim 8, further comprising a control system for synchronously controlling the liquid crystal panel and the light source according to image data, wherein when the control system controls the output power of the illumination light to increase/decrease, the control system controls the pulse width modulation signal of the liquid crystal panel so that the equivalent drive voltage value decreases/increases accordingly.

10. The display device according to claim 9, wherein the display device further comprises a memory for storing a look-up table that establishes a relationship between the equivalent driving voltage value and the waveform of the pulse width modulation signal.

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