Liquid crystal panel and display device

Abstract

The application discloses a liquid crystal panel and a display device. The liquid crystal panel comprises a liquid crystal layer and a driving circuit. The driving circuit generates a driving voltage based on a pulse width modulation signal. The driving voltage is loaded on both sides of the liquid crystal layer to drive the liquid crystal panel to display an image. The pulse width modulation signal generates the driving voltage according to a first voltage and a second voltage. The difference between the first voltage and the second voltage is less than the maximum voltage of the liquid crystal panel. The first voltage and the second voltage are both greater than zero and less than the maximum voltage. The driving voltage corresponds to an equivalent driving voltage value. The application modulates by the pulse width modulation signal, adjusts the interval range covered by the first voltage and the second voltage, and makes the difference between the first voltage and the second voltage less than the maximum voltage of the liquid crystal panel. The application combines the refinement of time segmentation and the precision of voltage driving liquid crystal, improves the modulation precision, and further improves the display gray scale effect of the liquid crystal panel.

Description

Technical Field

[0001] This application relates to the field of liquid crystal display drivers, and in particular to a liquid crystal panel and display device. Background Technology

[0002] LCoS (Liquid Crystal on Silicon) is a silicon-based microdisplay technology that combines CMOS integrated circuit design processes and liquid crystal packaging technology. Gray-scale accuracy is one of the key factors in the display performance of LCoS chips. However, in existing technologies, LCoS projection, when inputting an 8-bit gray-scale image signal, can only display 5-6 bits of grayscale.

[0003] LCoS driving methods include digital driving and analog driving. Analog driving utilizes Dynamic Random Access Memory (DRAM) to display different grayscale levels of pixels. The input display signal needs to be converted into an analog voltage signal by a digital-to-analog converter (DAC). The voltage difference between this signal and the common electrode signal is the voltage across the pixel. Analog driving modulates the pixel voltage by controlling the output voltage of the DAC, thereby achieving grayscale display control. Specifically, analog driving achieves grayscale display control by segmenting the driving voltage. However, analog driving has limitations in the precision of voltage segmentation, failing to achieve high-precision control, which affects the display effect of LCoS.

[0004] Digital driving typically utilizes Static Random-Access Memory (SRAM) to display different grayscale levels of pixels. The control of different grayscale levels in digital driving is achieved by modulating the on-time of pixel switches, i.e., pulse width modulation (PWM) control. In existing technologies, the driving voltage of LCoS is 0-5V, and PWM achieves grayscale display control by dividing the 0-5V range into equal steps. However, the voltage at the beginning and end of the driving voltage has very little impact on the liquid crystal response, resulting in ineffective PWM division at the beginning and end of the driving voltage. Consequently, the actual number of grayscale levels achieved visually is significantly lower than the designed grayscale level. Summary of the Invention

[0005] To improve the actual visual grayscale effect of an LCD panel, this application discloses an LCD panel including a liquid crystal layer and a driving circuit. The driving circuit generates a driving voltage based on a pulse width modulation signal. The driving voltage is applied to both sides of the liquid crystal layer to drive the LCD panel to display an image. The pulse width modulation signal generates the driving voltage according to a first voltage and a second voltage. The first voltage is less than the second voltage, and the difference between the first voltage and the second voltage is less than the maximum voltage of the LCD panel. Both the first voltage and the second voltage are greater than zero and less than the maximum voltage. For any frame of image data, the driving voltage corresponds to an equivalent driving voltage value.

[0006] The beneficial effects of this application are as follows: Unlike the prior art, this application uses pulse width modulation (PWM) signals for modulation. First, it reduces the voltage range covered by the first and second voltages, making the difference between them less than the maximum voltage of the LCD panel. This allows for a more precise match between the LCD response and the voltages applied to both sides of the LCD, avoiding areas where the LCD response is not obvious. Second, it obtains a more refined correspondence between voltage and grayscale by using pulse width modulation time division. This combines the refinement of time division with the precision of voltage-driven LCD, improving modulation accuracy and thus enhancing the grayscale display effect of the LCD panel.

[0007] In one implementation, during any frame of an image, the equivalent driving voltage value is equal to the time-weighted average of the first voltage and the second voltage.

[0008] In one embodiment, the liquid crystal panel is used to display an N-bit binary image, with the first voltage divided into two voltages. N The equivalent driving voltage value of the stage, and the voltage difference between the equivalent driving voltage values ​​of two adjacent stages is equal.

[0009] In one embodiment, the first voltage is the minimum response voltage of the liquid crystal panel, and the second voltage is the maximum response voltage of the liquid crystal panel.

[0010] In one embodiment, the difference between the effect of the first voltage and zero voltage on the transmittance of the liquid crystal panel is less than a first preset range; the difference between the effect of the second voltage and the maximum voltage on the transmittance of the liquid crystal panel is less than a second preset range.

[0011] In one embodiment, when the equivalent driving voltage is a first voltage, the relative transmittance of the liquid crystal panel is 100%, and when the driving voltage is a second voltage, the relative transmittance of the liquid crystal panel is 0%; or, when the equivalent driving voltage is a first voltage, the relative transmittance of the liquid crystal panel is 0%, and when the driving voltage is a second voltage, the relative transmittance of the liquid crystal panel is 100%.

[0012] In one embodiment, the first voltage is not less than 1.6V and the second voltage is not greater than 4.3V.

[0013] This application also includes a display device comprising a liquid crystal panel as described in any of the above embodiments, and a light source emitting illumination light, wherein the liquid crystal panel modulates the illumination light emitted by the light source to generate image light.

[0014] In one embodiment, the display device further includes a control system for synchronously controlling the liquid crystal panel and the light source according to image data. 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 to reduce / increase the equivalent driving voltage value accordingly.

[0015] In one embodiment, the display device further includes a memory for storing a lookup table that establishes a relationship between the equivalent drive voltage value and the waveform of the pulse width modulation signal.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 These are the electro-optical characteristic curves of existing display panels;

[0019] Figure 2 This is a schematic diagram of the structure of an embodiment of the liquid crystal panel of this application;

[0020] Figure 3 This is a schematic diagram of the pulse width modulation signal of this application;

[0021] Figure 4 This is the electro-optic characteristic curve of the liquid crystal panel of this application. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this application, the liquid crystal panel and display device provided in this application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It is understood that the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] The terms "first," "second," etc., used in this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0024] In the display field, LCoS (Liquid Crystal on Silicon) microdisplay chips are widely used. LCoS is a silicon-based microdisplay technology that combines CMOS integrated circuit design processes and liquid crystal packaging technology. Resolution, fill factor, reflectivity, frame rate, power consumption, display area, grayscale accuracy, and linearity are key performance characteristics of LCoS chips. LCoS pixels can be driven in two ways: analog and digital. Analog-driven LCoS chips offer advantages such as relatively simple algorithms, stable grayscale, and low power consumption; however, their limited control precision affects the display effect. Digital driving, on the other hand, provides high-precision grayscale control, improving the display performance of LCoS.

[0025] Specifically, when describing digital images, the color bit depth of an image is also called grayscale resolution. Grayscale resolution refers to the number of grayscale gradients used when preparing an image for display. Compared to digital images with low grayscale resolution, digital images with higher grayscale resolution consist of more grayscale gradients and are displayed with a greater bit depth.

[0026] LCoS chips control the phase transition of liquid crystals through electric field voltage, and the resulting curves are called EO curves (electro-optical curves), i.e., electro-optic response curves, as shown in the figure below. Figure 1 As shown, Figure 1 This is the electro-optic characteristic curve of a display panel using existing technology. Specifically, the relative transmittance is the proportion of light emitted from the liquid crystal panel that passes through the polarization selector in the downstream optical path, with the relative transmittance taken as 100% when the actual transmittance is at its maximum.

[0027] like Figure 1As shown, in this embodiment, the relative transmittance of the liquid crystal panel increases with the increase of the applied voltage; the relative transmittance of the liquid crystal panel is greatest when the applied voltage is minimum, and the relative transmittance of the liquid crystal panel is minimum when the applied voltage is maximum. It can be understood that if the polarization selector converts the characteristics of transmitted and reflected S-rays and P-rays, the transmittance could also be minimum when the applied voltage is minimum and maximum when the applied voltage is maximum. For ease of explanation and to avoid confusion, this application only illustrates one method.

[0028] Digital images are typically implemented using PWM (Pulse Width Modulation), which requires a fixed bit depth. Although the color bit depth and EO bit depth are defined independently for separate matrices, they can be correlated via a lookup table to map color grayscale to EO grayscale. The biggest resource consumption in LCoS is the PWM operation per pixel unit. An 8-bit EO bit depth has reached the limit of mainstream CMOS processes and acceptable power consumption. Therefore, further improving grayscale resolution by increasing the number of bits is very difficult.

[0029] This application provides a liquid crystal panel that reduces the range of electric field voltage by adjusting the operating voltage and cutoff voltage of the pulse width modulation signal, thereby increasing the actual display grayscale of the image displayed on the liquid crystal panel.

[0030] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of an embodiment of the liquid crystal panel of this application, as shown below. Figure 2 As shown, the 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 a pulse width modulation signal, and the driving voltage is applied to both sides of the liquid crystal layer 11 to drive the liquid crystal panel 10 to display images.

[0031] Pulse width modulation (PWM) is a digital control method that modulates the bias of the transistor base or MOSFET gate according to changes in the load, thereby altering the conduction time of the transistor or MOSFET and thus changing the output of the switching power supply. This method allows the power supply output voltage to remain constant under changing operating conditions and is a highly effective technique for controlling analog circuits using digital signals from a microprocessor.

[0032] Pulse Width Modulation (PWM) signals, using a high-resolution counter, employ a square wave duty cycle modulated to encode the level of a specific signal. The PWM signal remains digital because at any given moment, the full-amplitude DC power supply is either fully ON or fully OFF. A voltage or current source is applied to the analog load as a repeating sequence of ON or OFF pulses. ON indicates that DC power is being applied to the load, and OFF indicates that the power supply is being disconnected.

[0033] Further reading Figure 3 , Figure 3 This is a schematic diagram of the pulse width modulation signal of this application. (For example...) Figure 3 As shown, in this embodiment, the pulse width modulation signal generates a driving voltage based on the first voltage and the second voltage. The first voltage V0 is used as the working state of the pulse width modulation signal, that is, the voltage of the pulse width modulation signal is at full amplitude (ON). The second voltage V1 is used as the cutoff state of the pulse width modulation signal, that is, the voltage of the pulse width modulation signal is off (OFF). 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.

[0034] Specifically, the driving circuit 12 is used to adjust the difference between the first voltage V0 and the second voltage V1 of the pulse width modulation signal. The adjusted difference is less than the maximum voltage of the liquid crystal panel 10, so as to increase the grayscale of the image displayed by the liquid crystal panel 10.

[0035] The maximum voltage of the liquid crystal panel 10 is limited by the semiconductor transistors inside the liquid crystal panel 10. The maximum voltage is the highest voltage that the transistors can support. In a typical wafer fab, the highest voltage that the semiconductor transistors inside the liquid crystal panel 10 can support is 5V. 0V and 5V are used as the working and cutoff voltages for the pulse width modulation signal, respectively.

[0036] Using 0V and 5V directly as the operating and cutoff voltages has several drawbacks. First, the voltage difference between the two is too large. In digital modulation, the actual voltage difference applied across a liquid crystal pixel at any given time is only 0 or 5. This causes adjacent liquid crystal pixels to be affected by the excessive voltage difference, leading to pixel crosstalk, incorrect image display, and decreased contrast. Second, within a voltage range close to 0V or 5V, the liquid crystal response is not obvious, making it difficult to distinguish the brightness differences between small or large grayscale values. For example, a pixel with grayscale 1 and a pixel with grayscale 2 should have a perceived brightness difference of 2 times, but due to the indistinct liquid crystal response, the human eye cannot distinguish them, resulting in an actual grayscale level equivalent to only 5 or 6 bits of data.

[0037] Typically, when using 0V and 5V as the working and cutoff voltages for pulse width modulation (PWM) signals, the LCD panel can only display 5-6 bits of grayscale when receiving an 8-bit grayscale image signal, resulting in insufficient image display quality.

[0038] Therefore, in the embodiments 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.

[0039] Specifically, when the voltage is less than the minimum response voltage or greater than the maximum response voltage, the effect of the liquid crystal on the transmittance is not significant. The difference between the effect of the first voltage V0 and zero voltage (i.e., 0V) on the transmittance of the liquid crystal panel is less than a first preset range; the difference between the effect of the second voltage V1 and the maximum voltage (i.e., 5V) on the transmittance of the liquid crystal panel is less than a second preset range. The first preset range can be, for example, no more than 0.4%. The second preset range can be, for example, no more than 0.4%.

[0040] Depend on Figure 1 It is known that when the applied voltage to the liquid crystal panel increases from 0V to 1.6V, the relative transmittance of the liquid crystal panel remains essentially unchanged, maintaining around 100%; when the applied voltage increases from 4.3V to 5V, the relative transmittance of the liquid crystal panel remains essentially unchanged, maintaining around 0%. In other words, the low voltage region from 0V to 1.6V and the high voltage region from 4.3V to 5V have little or no impact on the phase transition of the liquid crystal in the liquid crystal panel. Therefore, in this embodiment, 1.6V and 4.3V are specifically used as the working voltage and cutoff voltage of the pulse width modulation signal, respectively, i.e., the first voltage V0 and the second voltage V1. In other embodiments of the present invention, in order to avoid voltage ranges where the liquid crystal response is not significant, the first voltage is not less than 1.6V, and the second voltage is not greater than 4.3V.

[0041] like Figure 3 As shown, the pulse width modulation signal has multiple periods T, where each period T corresponds to an image frame. The driving circuit 12 modulates multiple consecutive image frames by modulating the signal with multiple consecutive periods T. Multiple continuously changing image frames form an image for display.

[0042] Each period T is divided into multiple preset time periods Δt. The duty cycle of the pulse width modulation signal is the ratio of the total time of the second voltage V1 within each period T to the time of period T.

[0043] Optionally, the first voltage V0 and the second voltage V1 may vary continuously or intermittently 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.

[0044] like Figure 3 As shown, within the first period T, both the first voltage V0 and the second voltage V1 change continuously. In this case, one period T includes only one pulse signal of the first voltage V0 and one pulse signal of the second voltage V1, also known as the ONE-ON-ONE-OFF mode. Since the liquid crystal itself has a certain response time, the change in actual relative transmittance caused by pulse width modulation will have a relatively long rise or fall edge. Therefore, the ONE-ON-ONE-OFF mode can achieve a more precise modulation effect by reducing the number of rise and fall times in the signal waveform. Therefore, preferably, the ONE-ON-ONE-OFF mode is selected to modulate the liquid crystal within any period T.

[0045] During the second period T, the second voltage V1 changes intermittently, while the first voltage V0 changes continuously. At this time, one period T includes one pulse signal of the first voltage V0 and two pulse signals of the second voltage V1.

[0046] During the third cycle T, both the first voltage V0 and the second voltage V1 change intermittently. At this time, one cycle T includes two pulse signals of the first voltage V0 and three pulse signals of the second voltage V1.

[0047] Optionally, this application does not limit the number of pulse signals for the first voltage V0 and the second voltage V1 within a single cycle. Figure 3 This is a schematic diagram of a pulse width modulation signal only.

[0048] In this embodiment, the liquid crystal panel 10 is used to display an N-bit binary image, and each period T is divided into 2... N A preset time period Δt. The LCD panel 10 has 2 N The LCD panel 10 has several gray levels to display an N-bit binary image. In the nth gray level of the LCD panel 10, the total time of the second voltage V1 is n preset time intervals Δt, where n is less than 2^n. N Integers. Specifically, n = 0, 1, 2...2 N -1. Where N can be 8, 10, or 12, meaning the binary image can be an 8-bit, 10-bit, or 12-bit RGB image. The first voltage V0 and the second voltage V1 are divided into 2... N The voltage level is defined as follows: the nth voltage level corresponds to the nth gray level, and the voltage difference between two adjacent voltage levels is equal.

[0049] Specifically, the number of preset time periods Δt occupied by the second voltage V1 within each cycle T is different, and the corresponding gray levels are also different. At the same time, the number of preset time periods Δt occupied by the second voltage V1 within each cycle T affects the total time of the second voltage V1. Since the duty cycle of the pulse width modulation signal is proportional to the total time of the adjusted second voltage V1 within each cycle T, the gray level is proportional to the duty cycle.

[0050] The number of preset time periods Δt is directly proportional to the gray level; each additional preset time period Δt increases the gray level by one level. When the number of preset time periods Δt occupied by the adjusted second voltage V1 within each cycle T is zero, it corresponds to the lowest gray level; when the number of preset time periods Δt occupied by the adjusted second voltage V1 within each cycle T is 2... N When, it corresponds to the highest gray level.

[0051] Each driving voltage corresponds to an equivalent driving voltage value. The driving circuit 12 calculates the equivalent driving voltage value based on the duty cycle, the difference, and the first voltage V0. The equivalent driving voltage value is equal to the time-weighted average of the first voltage V0 and the second voltage V1. The specific calculation formula is as follows:

[0052] V PWM =D*(V1-V0)+V0

[0053] Among them, V PWM The equivalent driving voltage value is given by denoted by D, which is the duty cycle. 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.

[0054] By fitting the calculated driving voltage with data, the electro-optic characteristic curve of the liquid crystal panel in this embodiment can be obtained, such as... Figure 4 As shown, Figure 4 This is the electro-optic characteristic curve of the liquid crystal panel of this application, where the "driving voltage" on the horizontal axis corresponds to the equivalent driving voltage value.

[0055] As can be seen from the above calculation formula, the driving voltage is directly proportional to the duty cycle, and the gray level is directly proportional to the duty cycle. Therefore, it can be deduced that the driving voltage is directly proportional to the gray level. Thus, 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 a constant value.

[0056] 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 difference between the adjusted second voltage V1 and the first voltage V0 divided by 2. N .

[0057] This embodiment further illustrates the concept using an 8-bit binary image as an example, where N equals 8, 2N The value is equal to 256. When the LCD panel 10 is used to display an 8-bit binary image, the LCD panel 10 is configured with 256 gray levels, where the lowest gray level is V(0), and the driving voltage is the first voltage V0; the highest gray level is V(255), and the driving voltage is the second voltage V1. The first voltage V0 is the maximum response voltage of the LCD panel 10, and the second voltage V1 is the minimum response voltage of the LCD panel 10.

[0058] Depend on Figure 4 As can be seen, in this embodiment, the relative transmittance of the liquid crystal panel 10 is negatively correlated with the equivalent driving voltage value, and the relative transmittance of the liquid crystal panel 10 decreases as the driving voltage increases. Specifically, 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%.

[0059] It is understandable that this relative transmittance is related to the polarizing beam splitter at the emitting end of the liquid crystal panel 10 and whether a waveplate is set in the optical path system. Taking LCD as an example, if the transmission / reflection characteristics of the polarizing beam splitter at the emitting end for S-rays and P-rays are changed, the curve will be flipped, causing 100% and 0% to be swapped. Taking LCoS as an example, if the 1 / 4 waveplate near the LCoS liquid crystal layer is increased or decreased, 100% and 0% will also be swapped.

[0060] This invention specification uses only one scenario as an example, mainly to illustrate that the first voltage V0 and the second voltage V1 correspond to either 100% relative transmittance or 0% relative transmittance, respectively.

[0061] Unlike existing technologies that use 0V and 5V as the operating and cutoff voltages for the pulse width modulation signal, this embodiment adjusts the first voltage V0 to 1.6V and the second voltage V1 to 4.3V to reduce the range of driving voltage variation. Comparing the prior art with this embodiment, it can be seen that this embodiment, by adjusting the first voltage V0 and the second voltage V1 of the pulse width modulation signal, makes the difference between the first voltage V0 and the second voltage V1 less than the maximum voltage of the liquid crystal panel 10, i.e., less than 5V.

[0062] When the number of gray levels is the same, the voltage difference between the driving voltages corresponding to two adjacent gray levels is reduced compared to the prior art. This allows the liquid crystal panel 10 to change the gray level with a smaller voltage change value, effectively improving the response speed of the liquid crystal panel 10 and the gray level resolution capability of the liquid crystal panel 10. This improves the gray level effect of the liquid crystal panel 10 by 1-2 bits on the basis of the prior art, thereby improving the gray level effect of the liquid crystal panel 10 and increasing the gray level of the image displayed by the liquid crystal panel 10.

[0063] This application also provides a display device, including a light source and a liquid crystal panel. The liquid crystal panel has already been described in the above embodiments and will not be repeated here. The light source emits illumination light, which is incident on the liquid crystal panel. The liquid crystal panel modulates the illumination light emitted by the light source to display image light.

[0064] Furthermore, when the display device is a projection device, it also includes a projection lens for amplifying the image light emitted from the liquid crystal panel and projecting it onto a predetermined position to form a display image. When the display device is an AR or VR device, it also includes an optical coupler for coupling the image light emitted from the liquid crystal panel to the human eye.

[0065] In this invention, the digital pulse width modulation method is used to modulate the liquid crystal panel, resulting in a very uniform distribution of the equivalent driving voltage value, which is particularly convenient for numerical mapping. When this technical solution is applied to Global Dimming or Global Brightening applications, the change of the equivalent driving voltage value when the light source brightness changes is simple and convenient.

[0066] Specifically, in one 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 image data. 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 to reduce / increase the equivalent driving voltage value accordingly.

[0067] Controlling the pulse width modulation signal can be achieved using a lookup table. Specifically, in this embodiment, the display device further includes a memory for storing the lookup table, which establishes the relationship between the equivalent drive voltage value and the waveform of the pulse width modulation signal.

[0068] For example, when the overall image is dark, a global dimming program is activated, reducing the brightness L of the conventional light source to αL. To display the image correctly, the overall grayscale value of the image needs to be increased, and the duty cycle of the second voltage V1 needs to be increased from D to βD. This causes a corresponding change in the equivalent driving voltage value. Then, the pulse width modulation signal waveform used to drive each pixel is obtained through a lookup table and output to both ends of the liquid crystal pixel. In the digital modulation display method of this invention, the human eye's perception of brightness is precisely obtained by the time integral of the brightness of each frame, which corresponds exactly to the equivalent driving voltage value obtained by the time duty cycle of the first voltage V0 and the second voltage V1. Therefore, a more convenient matching can be achieved.

[0069] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A liquid crystal panel, characterized in that, The device includes a liquid crystal layer and a driving circuit. The driving circuit generates a driving voltage based on a pulse width modulation signal. The driving voltage is applied to both sides of the liquid crystal layer to drive the liquid crystal panel to display an image. The pulse width modulation signal generates the driving voltage based on a first voltage and a second voltage. The first voltage is less than the second voltage, and the difference between the first voltage and the second voltage is less than the maximum voltage of the liquid crystal panel. Both the first voltage and the second voltage are greater than zero and less than the maximum voltage. Each driving voltage corresponds to an equivalent driving voltage value.

2. The liquid crystal panel according to claim 1, characterized in that, During any frame of an image, the equivalent driving voltage value is equal to the time-weighted average of the first voltage and the second voltage.

3. The liquid crystal panel according to claim 2, characterized in that, The liquid crystal panel is used to display an N-bit binary image, and the first voltage to the second voltage is divided into 2... N The equivalent driving voltage value of the stage, and the voltage difference between the equivalent driving voltage values ​​of two adjacent stages are equal.

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

5. The liquid crystal panel according to claim 4, characterized in that, The difference between the effect of the first voltage and zero voltage on the transmittance of the liquid crystal panel is less than a first preset range; the difference between the effect of the second voltage and the maximum voltage on the transmittance of the liquid crystal panel is less than a second preset range.

6. The liquid crystal panel according to claim 5, characterized in that, When the equivalent driving voltage is the first voltage, the relative transmittance of the liquid crystal panel is 100%; when the driving voltage is the second voltage, the relative transmittance of the liquid crystal panel is 0%. Alternatively... When the equivalent driving voltage is the first voltage, the relative transmittance of the liquid crystal panel is 0%; when the driving voltage is the second voltage, the relative transmittance of the liquid crystal panel is 100%.

7. The liquid crystal panel according to any one of claims 1-3, characterized in that, The first voltage is not less than 1.6V, and the second voltage is not greater than 4.3V.

8. A display device, characterized in that, The liquid crystal panel includes any one of claims 1-7, and further includes a light source that emits illumination light, wherein the liquid crystal panel modulates the illumination light emitted by the light source to generate image light.

9. The display device according to claim 8, characterized in that, The display device further includes a control system for synchronously controlling the liquid crystal panel and the light source according to image data. 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 to reduce / increase the equivalent driving voltage value accordingly.

10. The display device according to claim 9, characterized in that, The display device further includes a memory for storing a lookup table that establishes the relationship between the equivalent drive voltage value and the waveform of the pulse width modulation signal.

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