Voltage switching circuit, liquid crystal display device, and voltage switching method

Abstract

This disclosure provides a voltage switching circuit, a liquid crystal display device, and a voltage switching method, relating to the field of circuit technology. The voltage switching circuit includes at least two grayscale reference voltage generation circuits and a grayscale reference voltage selector. The at least two grayscale reference voltage generation circuits are used to generate at least two sets of grayscale reference voltages respectively through resistor voltage division. The grayscale reference voltage selector is used to select one set as the target grayscale reference voltage from the at least two sets of grayscale reference voltages. The voltage switching circuit provided in this disclosure, on the one hand, can provide multiple sets of grayscale reference voltages through resistor voltage division to meet different needs; on the other hand, by selecting one set as the target grayscale reference voltage through the grayscale reference voltage selector, the delay of the target grayscale reference voltage can be reduced.

Description

Technical Field

[0001] This disclosure relates to the field of circuit technology, and more specifically, to a voltage switching circuit, a liquid crystal display device, and a voltage switching method. Background Technology

[0002] The voltage switching circuits in related technologies either can only generate one set of grayscale reference voltages, which cannot meet the needs of different grayscale reference voltages; or they have a large delay when switching between multiple sets of grayscale reference voltages, which cannot meet the needs of grayscale reference voltages with high real-time performance.

[0003] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this disclosure is to provide a voltage switching circuit, a liquid crystal display device, and a voltage switching method that can generate multiple sets of grayscale reference voltages through resistor voltage division, while also meeting the time delay requirement of determining one set as the target grayscale reference voltage from the multiple sets of grayscale reference voltages.

[0005] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.

[0006] This disclosure provides a voltage switching circuit, including: at least two grayscale reference voltage generation circuits, used to generate at least two sets of grayscale reference voltages respectively through resistor voltage division; and a grayscale reference voltage selector, used to select one set as the target grayscale reference voltage from the at least two sets of grayscale reference voltages.

[0007] In some exemplary embodiments of this disclosure, at least two grayscale reference voltage generation circuits include: a dynamic display grayscale reference voltage generation circuit, configured to generate n dynamic display grayscale reference voltages based on a dynamic display analog voltage and a dynamic display voltage divider resistor, as one set of grayscale reference voltages, where n is an integer greater than 1; an inserted black frame grayscale reference voltage generation circuit, configured to generate n inserted black frame grayscale reference voltages based on an inserted black frame analog voltage and an inserted black frame voltage divider resistor, as one set of grayscale reference voltages; a zero-reset grayscale reference voltage generation circuit, configured to generate n zero-reset grayscale reference voltages based on a zero-reset analog voltage and a zero-reset voltage divider resistor, as one set of grayscale reference voltages; and a static display grayscale reference voltage generation circuit, configured to generate n static display grayscale reference voltages based on a static display analog voltage and a static display voltage divider resistor, as one set of grayscale reference voltages.

[0008] In some exemplary embodiments of this disclosure, the grayscale reference voltage selector includes n selection switches, wherein the selection switches are used to select a set as the target grayscale reference voltage from n dynamically displayed grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n statically displayed grayscale reference voltages according to a first control signal and a second control signal.

[0009] In some exemplary embodiments of this disclosure, the difference between the static display analog voltage and the common electrode voltage of the liquid crystal screen is between a first liquid crystal voltage and a second liquid crystal voltage, wherein the liquid crystal screen is in a static display state when it is between the first liquid crystal voltage and the second liquid crystal voltage; the difference between the dynamic display analog voltage and the common electrode voltage is between a third liquid crystal voltage and a fourth liquid crystal voltage, wherein the liquid crystal screen is in a dynamic display state when it is between the third liquid crystal voltage and the fourth liquid crystal voltage; the difference between the inserted black frame analog voltage and the common electrode voltage is the fourth liquid crystal voltage; and the difference between the zeroing analog voltage and the common electrode voltage is the fifth liquid crystal voltage.

[0010] In some exemplary embodiments of this disclosure, the voltage switching circuit further includes: a grayscale reference voltage selection controller, configured to send a control signal to the grayscale reference voltage selector; the grayscale reference voltage selector is further configured to select one set as a target grayscale reference voltage from at least two sets of grayscale reference voltages according to the control signal.

[0011] In some exemplary embodiments of this disclosure, the voltage switching circuit further includes: a liquid crystal screen source driving circuit, configured to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the liquid crystal screen.

[0012] This disclosure provides a liquid crystal display device, including the voltage switching circuit described in any embodiment of this disclosure.

[0013] In some exemplary embodiments of this disclosure, the liquid crystal display device further includes a liquid crystal screen source driving circuit and a liquid crystal screen. The liquid crystal screen source driving circuit is configured to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the liquid crystal screen.

[0014] In some exemplary embodiments of this disclosure, the liquid crystal screen includes a cholesteric liquid crystal screen.

[0015] This disclosure provides a voltage switching method, including: generating at least two sets of grayscale reference voltages by resistor voltage division; and selecting one set of grayscale reference voltages as a target grayscale reference voltage.

[0016] In some exemplary embodiments of this disclosure, generating at least two sets of grayscale reference voltages through resistor voltage division includes: generating n dynamic display grayscale reference voltages based on dynamic display analog voltage and dynamic display voltage divider resistors, as one set of grayscale reference voltages, where n is an integer greater than 1; generating n black frame grayscale reference voltages based on black frame insertion analog voltage and black frame insertion voltage divider resistors, as one set of grayscale reference voltages; generating n zero-level grayscale reference voltages based on zero-level analog voltage and zero-level voltage divider resistors, as one set of grayscale reference voltages; and generating n static display grayscale reference voltages based on static display analog voltage and static display voltage divider resistors, as one set of grayscale reference voltages.

[0017] In some exemplary embodiments of this disclosure, selecting one set of grayscale reference voltages from at least two sets as the target grayscale reference voltage includes: selecting one set of n dynamic display grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n static display grayscale reference voltages as the target grayscale reference voltage according to a first control signal and a second control signal.

[0018] The voltage switching circuit provided in some embodiments of this disclosure, on the one hand, can generate multiple sets of gray-level reference voltages by providing at least two gray-level reference voltage generation circuits through resistor voltage division; on the other hand, by providing a gray-level reference voltage selector, a set of gray-level reference voltages can be selected from the at least two sets of gray-level reference voltages as the target gray-level reference voltage, thereby reducing the delay in providing the target gray-level reference voltage and thus meeting the time delay requirements of the provided target gray-level reference voltage.

[0019] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this disclosure. Attached Figure Description

[0020] The above and other objects, features and advantages of this disclosure will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0021] Figure 1 A schematic diagram of a PGAMMA circuit according to an embodiment of the present disclosure is shown.

[0022] Figure 2 A schematic diagram of a voltage switching circuit according to an embodiment of the present disclosure is shown.

[0023] Figure 3 A schematic diagram showing the transmittance curve of a cholesteric liquid crystal in an embodiment of the present disclosure is shown.

[0024] Figure 4 A schematic diagram of a dynamic display grayscale reference voltage generation circuit is shown in an embodiment of this disclosure.

[0025] Figure 5 This diagram illustrates a grayscale reference voltage generation circuit for inserting a black frame according to an embodiment of the present disclosure.

[0026] Figure 6 A schematic diagram of a zero-grayscale reference voltage generation circuit according to an embodiment of this disclosure is shown.

[0027] Figure 7 A schematic diagram of a static display grayscale reference voltage generation circuit is shown in an embodiment of this disclosure.

[0028] Figure 8 A schematic diagram of a liquid crystal display device according to an embodiment of the present disclosure is shown.

[0029] Figure 9 A schematic diagram of a grayscale reference voltage selector is shown in an embodiment of this disclosure.

[0030] Figure 10 A flowchart of a voltage switching method according to an embodiment of this disclosure is shown. Detailed Implementation

[0031] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0032] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of the specific details omitted, or other methods, apparatuses, steps, etc., can be employed. In other instances, well-known structures, methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0033] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. The symbol " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0034] In this disclosure, unless otherwise expressly specified and limited, the term "connection" and similar terms should be interpreted broadly, for example, it can refer to an electrical connection or the ability to communicate with each other; it can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0035] In this embodiment, the grayscale reference voltage refers to the driving voltage corresponding to different grayscale levels. For example, 256 grayscale levels correspond to 256 grayscale reference voltage values. It is understood that the 256 is only used as an example and can be set according to the actual scenario. In some embodiments, the grayscale reference voltage can also be called GAMMA voltage. For example, GAMMA voltage is a set of stepped voltages in the LCD (Liquid Crystal Display) driving circuit. It generates driving voltages corresponding to different grayscale levels through a voltage divider circuit, which can be used to compensate for the non-linear perception of brightness by the human eye and ensure smooth grayscale transitions. GAMMA voltage is the voltage divider reference of the driving circuit and belongs to a type of reference voltage. GAMMA voltage is directly related to grayscale display, therefore it can also be called grayscale voltage. GAMMA voltage is a type of grayscale reference voltage used to provide driving references for different grayscale levels.

[0036] In some embodiments, GAMMA voltages can be generated using resistor dividers, referred to as a resistor divider GAMMA circuit. For example, an analog voltage is divided into GAMMA voltages using a series of voltage-dividing resistors. For instance, an analog voltage is divided using voltage-dividing resistors 1, 2, ..., n-1, and resistor n to obtain GAMMA voltage 1, GAMMA voltage 2, ..., n-1, and GAMMA voltage n, where n is an integer greater than 1. A single resistor series can only produce one set of GAMMA voltages and cannot precisely provide the multiple GAMMA voltages required by a liquid crystal display (e.g., cholesteric liquid crystal) device in different display states and during switching between display states.

[0037] In other embodiments, the GAMMA voltage can be generated using a PGAMMA circuit (Programmable GAMMA circuit). The GAMMA voltage can be rewritten by modifying the internal registers of the PGAMMA circuit.

[0038] Figure 1An exemplary PGAMMA circuit is provided, comprising a programmable GAMMA generator 110 and a programmable GAMMA generator controller 120. The programmable GAMMA generator 110 internally includes a register 111. The programmable GAMMA generator controller 120 sends programmable GAMMA generator control signals to the programmable GAMMA generator 110 to control the rewriting of the internal register 111 of the programmable GAMMA generator 110, thereby adjusting a set of GAMMA voltages (e.g., including GAMMA voltage 1 to GAMMA voltage n) input to the source driver chip 130.

[0039] exist Figure 1 In this embodiment, although multiple sets of different GAMMA voltages can be provided, since the programmable GAMMA generator only has one analog voltage input, if the programmable GAMMA generator outputs multiple sets of GAMMA voltages, when switching between different GAMMA voltages, the programmable GAMMA generator controller (e.g., CPU (Central Processing Unit)) needs to send a programmable GAMMA generator control signal to the programmable GAMMA generator via a bus (e.g., I2C, SPI (Serial Peripheral Interface)). This signal first erases the programmable GAMMA generator's internal registers, then rewrites them, and finally outputs the GAMMA voltage, completing the switching between different GAMMA voltages. Limited by bus transmission speed and register rewriting speed, this results in a significant delay.

[0040] Figure 2 A schematic diagram of a voltage switching circuit according to an embodiment of this disclosure is shown. For example... Figure 2 As shown, the voltage switching circuit 200 provided in this embodiment includes at least two grayscale reference voltage generation circuits (e.g., grayscale reference voltage generation circuits 1 to m in the figure, where m is an integer greater than 1) and a grayscale reference voltage selector 300. Grayscale reference voltage generation circuits 1 to m are respectively used to generate at least two sets of grayscale reference voltages through resistor voltage division, for example, generating m sets of grayscale reference voltages. The grayscale reference voltage selector 300 is used to select one set from the at least two sets of grayscale reference voltages as the target grayscale reference voltage.

[0041] The voltage switching circuit provided in some embodiments of this disclosure, on the one hand, can generate multiple sets of gray-level reference voltages by providing at least two gray-level reference voltage generation circuits through resistor voltage division; on the other hand, by providing a gray-level reference voltage selector, a set of gray-level reference voltages can be selected from the at least two sets of gray-level reference voltages as the target gray-level reference voltage, eliminating the delay of the PGAMMA circuit rewriting the register to switch the GAMMA voltage, reducing the delay of providing the target gray-level reference voltage, thereby meeting the time delay requirements of the provided target gray-level reference voltage.

[0042] In an exemplary embodiment, at least two grayscale reference voltage generation circuits include: a dynamic display grayscale reference voltage generation circuit, configured to generate n dynamic display grayscale reference voltages based on a dynamic display analog voltage and a dynamic display voltage divider resistor, as one set of grayscale reference voltages, where n is an integer greater than 1; an inserted black frame grayscale reference voltage generation circuit, configured to generate n inserted black frame grayscale reference voltages based on an inserted black frame analog voltage and an inserted black frame voltage divider resistor, as one set of grayscale reference voltages; a zero-reset grayscale reference voltage generation circuit, configured to generate n zero-reset grayscale reference voltages based on a zero-reset analog voltage and a zero-reset voltage divider resistor, as one set of grayscale reference voltages; and a static display grayscale reference voltage generation circuit, configured to generate n static display grayscale reference voltages based on a static display analog voltage and a static display voltage divider resistor, as one set of grayscale reference voltages.

[0043] For example, the voltage switching circuit provided in this disclosure is applied to a liquid crystal display device to provide a grayscale reference voltage for the liquid crystal display device. In some embodiments, the liquid crystal display device includes a cholesteric liquid crystal (CLC) display. Due to its bistable characteristics and electric field driving mechanism, a cholesteric liquid crystal display requires different GAMMA voltages during the dynamic-to-steady-state switching process. For example, this disclosure belongs to the field of cholesteric liquid crystal displays, or the field of bistable displays.

[0044] Figure 3 A schematic diagram showing the transmittance curve of a cholesteric liquid crystal according to an embodiment of this disclosure is illustrated. Figure 3 The figure shows the transmittance curve of cholesteric liquid crystal. The liquid crystal between points a and b on the curve exhibits the cholesteric phase, representing the static / steady-state display range of the cholesteric liquid crystal, with corresponding liquid crystal voltages V1 (first liquid crystal voltage) and V2 (second liquid crystal voltage), respectively. The liquid crystal between points c and d on the curve exhibits the nematic phase, representing the dynamic display range of the cholesteric liquid crystal, with corresponding liquid crystal voltages V3 (third liquid crystal voltage) and V4 (fourth liquid crystal voltage), respectively. Different GAMMA voltages are required for cholesteric liquid crystals during dynamic display, static display, steady-state display, and switching between different display states.

[0045] For example, the switching process of cholesteric liquid crystal from dynamic to steady state is as follows: dynamic display - blacking out (i.e., inserting a black frame) - zeroing out - static display - steady state, where dynamic display, blacking out, zeroing out, and static display require different GAMMA voltages.

[0046] For example, the switching from steady state to dynamic state of cholesteric liquid crystal can be achieved by directly providing a reference voltage for the dynamic display grayscale.

[0047] In this embodiment, the Dynamic Display stage / state rapidly changes the arrangement of liquid crystal molecules, quickly refreshing the displayed content to present dynamic images, such as playing videos or dynamic scenes. The required dynamic display grayscale reference voltage at this time necessitates a relatively high driving voltage (e.g., 15V) to drive the molecules to deflect rapidly. At this point, the liquid crystal structure is in a nematic phase, ensuring that pixels can quickly respond to grayscale changes, reducing the response time to the millisecond level and ensuring smooth dynamic images. During this stage, the electric field intensity is high, and the liquid crystal molecules are in an active state. Therefore, the transmittance or reflectance of each grayscale level needs to be precisely controlled through the dynamic display grayscale reference voltage.

[0048] In this embodiment, during the Black Frame Insertion stage / state, a short-term high voltage (higher than the dynamic display grayscale reference voltage) is applied to rapidly turn the screen black (total black state) by inserting a black frame grayscale reference voltage. The voltage amplitude of the inserted black frame grayscale reference voltage needs to be large enough to establish a fast channel, allowing the liquid crystal molecules to transform from the nematic phase to the cholesteric phase.

[0049] In this embodiment, during the reset phase / state, the voltage rapidly drops from a high voltage (blackout voltage) to zero, transforming the liquid crystal molecules from the nematic phase to the cholesteric phase, restoring them to their initial alignment, and preparing for static display. The required grayscale reference voltage at this time is zero. By briefly shutting off the electric field, the elastic restoring force of the cholesteric liquid crystal is utilized to allow the molecules to reform their helical structure.

[0050] In this embodiment of the disclosure, the static display stage / state maintains a stable static image (such as text displayed on electronic paper). The required static display grayscale reference voltage at this time is a low sustaining voltage, utilizing the bistable characteristics of cholesteric liquid crystals to maintain the current optical state at a low voltage (e.g., 5V). The static display grayscale reference voltage must precisely match the reflectivity threshold of the target grayscale to ensure the contrast and uniformity of the static image.

[0051] In this embodiment, "steady state" refers to maintaining the final display state without requiring additional energy input. The required steady-state grayscale reference voltage can be zero or near-zero. In the bistable state, cholesteric liquid crystals spontaneously maintain their molecular structure without requiring an external electric field.

[0052] In this embodiment, by providing different GAMMA voltages for the cholesteric liquid crystal during the switching process from dynamic to steady state, a balance between response speed and power consumption, as well as matching of optical characteristics, can be achieved. Dynamic displays require high-voltage driving to accelerate response, but consume a lot of power; static displays rely on bistable operation, requiring only transient voltage and consuming little power. The stepped switching of the GAMMA voltage (dynamic-blackout-zeroing-static) optimizes the energy efficiency ratio. Simultaneously, different optical states (reflectivity / transmittance) at different stages must correspond to different GAMMA curves; otherwise, contrast distortion or grayscale jumps will occur. Furthermore, blackout and zeroing control the formation and destruction of the spiral structure through voltage polarity switching, achieving rapid switching between light absorption and reflection states.

[0053] For example, when cholesteric liquid crystals are applied to electronic paper (E-paper), during page turning, the display sequentially goes through dynamic display (high voltage refresh), blacking out (eliminating ghosting), zeroing, and static display (low voltage maintenance). After page turning, it enters a steady state to achieve low or zero power consumption.

[0054] Figure 4 This diagram illustrates a dynamic grayscale reference voltage generation circuit according to an embodiment of the present disclosure. Figure 4 As shown, the voltage switching circuit includes a dynamic display grayscale reference voltage generation circuit 210. The dynamic display grayscale reference voltage generation circuit 210 includes dynamic display voltage divider resistors 1, 2, ..., n-1, n, and n+1 connected in series, forming a resistor string. For example, one end of dynamic display voltage divider resistor 1 is connected to the dynamic display analog voltage, and the other end is connected to one end of dynamic display voltage divider resistor 2. The other end of dynamic display voltage divider resistor 2 is connected to one end of dynamic display voltage divider resistor 3. The others follow the same pattern. For example, one end of dynamic display voltage divider resistor n+1 is connected to one end of dynamic display voltage divider resistor n, and the other end can be grounded.

[0055] In this embodiment of the disclosure, the dynamic display analog voltage refers to the analog voltage used to generate a set of dynamic display grayscale reference voltages. The dynamic display analog voltage is sequentially divided by dynamic display voltage divider resistor 1, dynamic display voltage divider resistor 2... dynamic display voltage divider resistor n-1, dynamic display voltage divider resistor n, and dynamic display voltage divider resistor n+1, respectively generating dynamic display GAMMA voltage 1, dynamic display GAMMA voltage 2... dynamic display GAMMA voltage n, that is, n dynamic display grayscale reference voltages are used as a set of grayscale reference voltages.

[0056] Figure 5 This diagram illustrates a grayscale reference voltage generation circuit for inserting a black frame according to an embodiment of the present disclosure. Figure 5As shown, the voltage switching circuit includes a grayscale reference voltage generation circuit 220 for inserting black frames. The grayscale reference voltage generation circuit 220 for inserting black frames includes, in series, a black frame voltage divider resistor 1 (i.e., black frame voltage divider 1), a black frame voltage divider resistor 2 (i.e., black frame voltage divider 2), ... a black frame voltage divider resistor n-1 (i.e., black frame voltage divider n), a black frame voltage divider resistor n (i.e., black frame voltage divider n), and a black frame voltage divider resistor n+1 (i.e., black frame voltage divider n+1), forming another resistor string. For example, one end of the black frame voltage divider resistor 1 is connected to the black frame analog voltage (i.e., the black frame analog voltage), and the other end is connected to one end of the black frame voltage divider resistor 2. The other end of the black frame voltage divider resistor 2 is connected to one end of the black frame voltage divider resistor 3. The others follow the same pattern. For example, one end of the black frame voltage divider resistor n+1 is connected to one end of the black frame voltage divider resistor n, and the other end can be grounded.

[0057] In this embodiment of the disclosure, the black-level simulated voltage refers to the simulated voltage used to generate a set of black-level grayscale reference voltages. The black-level simulated voltage is sequentially divided by black-level voltage divider resistors 1, 2, ..., n-1, n, and n+1 to generate black-level GAMMA voltage 1, 2, ..., n, which together form another set of grayscale reference voltages.

[0058] Figure 6 This diagram illustrates a zero-grayscale reference voltage generation circuit according to an embodiment of the present disclosure. Figure 6 As shown, the voltage switching circuit includes a zero-grayscale reference voltage generation circuit 230. The zero-grayscale reference voltage generation circuit 230 includes zero-grayscale voltage divider resistors 1, 2, ..., n-1, n, and n+1 connected in series, forming another resistor string. For example, one end of zero-grayscale voltage divider resistor 1 is connected to the zero-grayscale analog voltage, and the other end is connected to one end of zero-grayscale voltage divider resistor 2. The other end of zero-grayscale voltage divider resistor 2 is connected to one end of zero-grayscale voltage divider resistor 3. The others follow the same pattern. For example, one end of zero-grayscale voltage divider resistor n+1 is connected to one end of zero-grayscale voltage divider resistor n, and the other end can be grounded.

[0059] In this embodiment of the disclosure, the zero-level analog voltage refers to the analog voltage used to generate a set of zero-level grayscale reference voltages. The zero-level analog voltage is sequentially divided by zero-level voltage divider resistor 1, zero-level voltage divider resistor 2... zero-level voltage divider resistor n-1, zero-level voltage divider resistor n, and zero-level voltage divider resistor n+1, respectively generating zero-level GAMMA voltage 1, zero-level GAMMA voltage 2... zero-level GAMMA voltage n, that is, n zero-level grayscale reference voltages as another set of grayscale reference voltages.

[0060] Figure 7This diagram illustrates a static display grayscale reference voltage generation circuit according to an embodiment of the present disclosure. Figure 7 As shown, the voltage switching circuit includes a static display grayscale reference voltage generation circuit 240. The static display grayscale reference voltage generation circuit 240 includes static display voltage divider resistors 1, 2, ..., n-1, n, and n+1 connected in series, forming another resistor string. For example, one end of static display voltage divider resistor 1 is connected to the static display analog voltage, and the other end is connected to one end of static display voltage divider resistor 2. The other end of static display voltage divider resistor 2 is connected to one end of static display voltage divider resistor 3. The others follow the same pattern. For example, one end of static display voltage divider resistor n+1 is connected to one end of static display voltage divider resistor n, and the other end can be grounded.

[0061] In this embodiment of the disclosure, the static display analog voltage refers to the analog voltage used to generate a set of static display grayscale reference voltages. The static display analog voltage is sequentially divided by static display voltage divider resistor 1, static display voltage divider resistor 2... static display voltage divider resistor n-1, static display voltage divider resistor n, and static display voltage divider resistor n+1, respectively generating static display GAMMA voltage 1, static display GAMMA voltage 2... static display GAMMA voltage n, that is, n static display grayscale reference voltages are used as a set of grayscale reference voltages.

[0062] The voltage switching circuit provided in this disclosure uses multiple sets of resistors in series to generate multiple sets of grayscale reference voltages, accurately providing different GAMMA voltages for cholesteric liquid crystals under different display states and during switching between different display states. The voltage switching circuit provided in this disclosure can also be referred to as a multi-GAMMA voltage switching circuit.

[0063] In an exemplary embodiment, the difference between the static display analog voltage and the common electrode voltage (VCOM) of the liquid crystal screen is between a first liquid crystal voltage and a second liquid crystal voltage, wherein the liquid crystal screen is in a static display state when it is between the first liquid crystal voltage and the second liquid crystal voltage; the difference between the dynamic display analog voltage and the common electrode voltage is between a third liquid crystal voltage and a fourth liquid crystal voltage, wherein the liquid crystal screen is in a dynamic display state when it is between the third liquid crystal voltage and the fourth liquid crystal voltage; the difference between the inserted black frame analog voltage and the common electrode voltage is the fourth liquid crystal voltage; and the difference between the zeroing analog voltage and the common electrode voltage is the fifth liquid crystal voltage.

[0064] For example, the dynamic display of analog voltage, the black-out analog voltage, the zero-reset analog voltage, and the static display of analog voltage all use the VCOM voltage as a reference.

[0065] For example, the difference between the dynamically displayed analog voltage and VCOM is between V3 and V4. For example, the values ​​of the dynamically displayed GAMMA voltage 1 to the dynamically displayed GAMMA voltage n (also referred to as the liquid crystal display GAMMA voltage 1 to n) depend on the requirements of the liquid crystal screen source driver chip or circuit, and this disclosure does not limit them.

[0066] For example, the static display shows the difference between the analog voltage and VCOM between V1 and V2.

[0067] For example, the difference between the blackening analog voltage and VCOM is V4. For example, the difference between the blackening GAMMA voltage 1 to the blackening GAMMA voltage n and VCOM is equal to V4.

[0068] For example, the difference between the zero-reset analog voltage and VCOM is 0V. For example, the difference between the zero-reset GAMMA voltage 1 to the zero-reset GAMMA voltage n and VCOM is equal to 0V.

[0069] In this embodiment of the disclosure, the VCOM voltage is a parameter in the liquid crystal display (LCD). The VCOM voltage is a reference voltage applied to the common electrode of the liquid crystal cell. In the LCD structure, each pixel includes a pixel electrode (controlled by a driving circuit) and a common electrode (VCOM). The voltage difference between the two forms an electric field, driving the liquid crystal molecules to deflect, thereby adjusting the amount of light transmitted to achieve image display. The voltage difference between the VCOM and the pixel electrode determines the liquid crystal deflection angle, directly affecting the pixel brightness and contrast.

[0070] In this embodiment, the liquid crystal voltage is the actual voltage difference applied across the liquid crystal layer, determined by both the pixel voltage (Vpixel) and the common electrode voltage (VCOM), for example, liquid crystal voltage = |Vpixel - VCOM|. In some embodiments, the GAMMA voltage is the direct source of the pixel voltage, then liquid crystal voltage = |GAMMA voltage - VCOM|. In other embodiments, the GAMMA voltage is not equal to the directly applied pixel voltage; the GAMMA voltage is a reference for the liquid crystal screen source drive circuit, and a specific pixel voltage is generated through resistor voltage division or a DAC (Digital-to-Analog Converter) circuit. In this case, the liquid crystal voltage is the absolute value of the difference between Vpixel and VCOM obtained after the GAMMA voltage is processed by the drive circuit. The liquid crystal voltage directly controls the deflection angle of the liquid crystal molecules, thereby adjusting the amount of light transmitted.

[0071] In an exemplary embodiment, the voltage switching circuit further includes: a grayscale reference voltage selection controller, configured to send a control signal to the grayscale reference voltage selector; the grayscale reference voltage selector is further configured to select one set as the target grayscale reference voltage from at least two sets of grayscale reference voltages according to the control signal.

[0072] In an exemplary embodiment, the voltage switching circuit further includes: a liquid crystal screen source driving circuit, configured to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the liquid crystal screen.

[0073] Furthermore, embodiments of this disclosure provide a liquid crystal display device, including the voltage switching circuit described in any embodiment of this disclosure.

[0074] In an exemplary embodiment, the liquid crystal display device further includes a liquid crystal screen source driving circuit and a liquid crystal screen. The liquid crystal screen source driving circuit is configured to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the liquid crystal screen.

[0075] In an exemplary embodiment, the liquid crystal screen includes a cholesteric liquid crystal screen.

[0076] like Figure 8 , Figure 9As shown, the voltage switching circuit 200 includes a grayscale reference voltage selector 300 (also called a GAMMA voltage selector) and a grayscale reference voltage selection controller 400 (e.g., a CPU, also called a GAMMA voltage selection controller). It dynamically displays GAMMA voltage 1, GAMMA voltage 2, ..., GAMMA voltage n-1, GAMMA voltage n; it blackens GAMMA voltage 1, GAMMA voltage 2, ..., GAMMA voltage n-1, GAMMA voltage n; it resets GAMMA voltage 1, GAMMA voltage 2, ..., GAMMA voltage n-1, GAMMA voltage n; and it statically displays GAMMA voltage 1, GAMMA voltage 2, ..., GAMMA voltage n-1, GAMMA voltage n, which is input to the grayscale reference voltage selector 300. The grayscale reference voltage selector 300 receives dynamic display GAMMA voltages 1 to n, blackout GAMMA voltages 1 to n, zero-reset GAMMA voltages 1 to n, and static display GAMMA voltages 1 to n. It also receives control signals (also called GAMMA voltage selector control signals) from the grayscale reference voltage selection controller 400. Based on the control signals, it selects one of the four sets of grayscale reference voltages as the target grayscale reference voltage, such as GAMMA voltages 1 to n as shown in the diagram. The voltage switching circuit 200 inputs GAMMA voltages 1 to n to the LCD screen source drive circuit 500 to drive the grayscale displayed on the LCD screen 600. The GAMMA voltage selection controller outputs control signals to the GAMMA voltage selector, controlling the GAMMA voltage selector to output the corresponding GAMMA voltage 1, GAMMA voltage 2, ... GAMMA voltage n-1, GAMMA voltage n for dynamic display, blackout, zeroing, and static display, thus completing the GAMMA voltage switching and supplying the source driver chip of the LCD screen to drive the LCD screen display.

[0077] The voltage switching circuit provided in this disclosure is a multi-GAMMA switching circuit. It uses a resistor series voltage divider to generate multiple sets of GAMMA voltages for different states such as dynamic display, blackout, zeroing, and static display, solving the problem of only being able to generate one set of GAMMA voltages. Furthermore, by controlling a GAMMA voltage selector, it selects one set of GAMMA voltages from these multiple sets to accurately provide different GAMMA voltages to the cholesteric liquid crystal during different display states and transitions between them. Using a GAMMA voltage selector to switch the output GAMMA voltage eliminates the delay caused by the PGAMMA circuit rewriting registers to switch the GAMMA voltage.

[0078] In some embodiments, n GAMMA voltages are output in different display states of the liquid crystal display device. For example, n dynamic display GAMMA voltages, n blackout GAMMA voltages, n zero-reset GAMMA voltages, and n static display GAMMA voltages. The value of n depends on the requirements of the liquid crystal screen source driver chip or the liquid crystal screen source driver circuit, such as 14, 18, etc., and this disclosure does not limit it.

[0079] For example, the control signal includes a first control signal and a second control signal. It is understood that the number of control signals included in the control signal depends on how many groups of grayscale reference voltages the grayscale reference voltage selector needs to select as the target grayscale reference voltage. For example, assuming a selection is made from two groups, then only one control signal is needed. Assuming a selection is made from three or four groups, then the control signal will include at least two control signals. Assuming a selection is made from five to eight groups, then the control signal will include at least three control signals. And so on.

[0080] In an exemplary embodiment, the grayscale reference voltage selector includes n selection switches, wherein the selection switches are used to select a set as the target grayscale reference voltage from n dynamically displayed grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n statically displayed grayscale reference voltages according to a first control signal and a second control signal.

[0081] Figure 9 A schematic diagram of a grayscale reference voltage selector according to an embodiment of this disclosure is shown. Figure 9As shown, the grayscale reference voltage selector 300 internally includes n 4-to-1 switches (i.e., n selection switches). The inputs of dynamically displayed GAMMA voltage 1, blacked-out GAMMA voltage 1, zeroed-out GAMMA voltage 1, and statically displayed GAMMA voltage 1 are fed into the first 4-to-1 switch; the inputs of dynamically displayed GAMMA voltage 2, blacked-out GAMMA voltage 2, zeroed-out GAMMA voltage 2, and statically displayed GAMMA voltage 2 are fed into the second 4-to-1 switch; ... the inputs of dynamically displayed GAMMA voltage n, blacked-out GAMMA voltage n, zeroed-out GAMMA voltage n, and statically displayed GAMMA voltage n are fed into the nth 4-to-1 switch. The first control signal S0 and the second control signal S1 control these n 4-to-1 switches to control the output of the grayscale reference voltage selector 300 to select one of the following GAMMA voltage 1: dynamic display GAMMA voltage 1, black GAMMA voltage 1, zero GAMMA voltage 1, and static display GAMMA voltage 1; GAMMA voltage 2: dynamic display GAMMA voltage 2, black GAMMA voltage 2, zero GAMMA voltage 2, and static display GAMMA voltage 2; ... GAMMA voltage n: dynamic display GAMMA voltage n, black GAMMA voltage n, zero GAMMA voltage n, and static display GAMMA voltage n.

[0082] For example, when S0 = 0 and S1 = 0, GAMMA voltage 1 = dynamically displayed GAMMA voltage 1, GAMMA voltage 2 = dynamically displayed GAMMA voltage 2, ..., GAMMA voltage n = dynamically displayed GAMMA voltage n. At this time, the GAMMA voltage selector outputs dynamically displayed GAMMA voltages.

[0083] When S0 = 0 and S1 = 1, GAMMA voltage 1 = static display GAMMA voltage 1, GAMMA voltage 2 = static display GAMMA voltage 2, ..., GAMMA voltage n = static display GAMMA voltage n. At this time, the GAMMA voltage selector outputs the static display GAMMA voltage.

[0084] When S0 = 1 and S1 = 0, GAMMA voltage 1 = black GAMMA voltage 1, GAMMA voltage 2 = black GAMMA voltage 2, ..., GAMMA voltage n = black GAMMA voltage n. At this time, the GAMMA voltage selector outputs the black GAMMA voltage.

[0085] When S0 = 1 and S1 = 1, GAMMA voltage 1 = zero-reset GAMMA voltage 1, GAMMA voltage 2 = zero-reset GAMMA voltage 2, ..., GAMMA voltage n = zero-reset GAMMA voltage n. At this time, the GAMMA voltage selector outputs the zero-reset GAMMA voltage.

[0086] Figure 10 A flowchart illustrating a voltage switching method according to an embodiment of this disclosure is shown. Figure 10 As shown in the figure, this disclosure provides a voltage switching method, including the following steps.

[0087] In S110, at least two sets of gray-scale reference voltages are generated by resistor voltage division.

[0088] In S120, one set of grayscale reference voltages is selected from at least two sets as the target grayscale reference voltage.

[0089] In an exemplary embodiment, generating at least two sets of grayscale reference voltages via resistor voltage division includes: generating n dynamic display grayscale reference voltages based on dynamic display analog voltages and dynamic display voltage divider resistors (e.g., dynamic display voltage divider resistors 1 to n+1) as one set of grayscale reference voltages, where n is an integer greater than 1; generating n black frame grayscale reference voltages based on black frame insertion analog voltages and black frame insertion voltage divider resistors (e.g., black frame voltage divider resistors 1 to n+1) as one set of grayscale reference voltages; generating n zero-level grayscale reference voltages based on zero-level analog voltages and zero-level voltage divider resistors (e.g., zero-level voltage divider resistors 1 to n+1) as one set of grayscale reference voltages; and generating n static display grayscale reference voltages based on static display analog voltages and static display voltage divider resistors (e.g., static display voltage divider resistors 1 to n+1) as one set of grayscale reference voltages.

[0090] In an exemplary embodiment, selecting one set of grayscale reference voltages from at least two sets of grayscale reference voltages as the target grayscale reference voltage includes: selecting one set of n dynamic display grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n static display grayscale reference voltages as the target grayscale reference voltage according to a first control signal and a second control signal.

[0091] Figure 10 Other aspects of the embodiments can be found in the other embodiments described above.

[0092] For example, this disclosure also provides a system having a liquid crystal display device. The system may be a mobile phone, desktop computer, laptop computer, tablet computer, vehicle computer, game console, printer, positioning device, wearable electronic device, smart sensor, virtual reality device, augmented reality device, or any other suitable electronic device having a liquid crystal display device.

[0093] Exemplary embodiments of this disclosure have been specifically shown and described above. It should be understood that this disclosure is not limited to the detailed structures, arrangements, or implementations described herein; rather, this disclosure is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A voltage switching circuit, characterized in that, include: At least two grayscale reference voltage generation circuits are used to generate at least two sets of grayscale reference voltages respectively through resistor voltage division; A grayscale reference voltage selector is used to select one set as the target grayscale reference voltage from at least two sets of grayscale reference voltages.

2. The circuit according to claim 1, characterized in that, At least two grayscale reference voltage generation circuits include: The dynamic display grayscale reference voltage generation circuit is used to generate n dynamic display grayscale reference voltages based on the dynamic display analog voltage and the dynamic display voltage divider resistor, so as to serve as one set of grayscale reference voltages, where n is an integer greater than 1; The grayscale reference voltage generation circuit for inserting black frames is used to generate n grayscale reference voltages for inserting black frames based on the analog voltage of the inserted black frames and the voltage divider resistor of the inserted black frames, so as to serve as one set of grayscale reference voltages. The zero-level grayscale reference voltage generation circuit is used to generate n zero-level grayscale reference voltages based on the zero-level analog voltage and the zero-level voltage divider resistor, which are used as one set of grayscale reference voltages. A static display grayscale reference voltage generation circuit is used to generate n static display grayscale reference voltages based on the static display analog voltage and the static display voltage divider resistor, which will serve as one set of grayscale reference voltages.

3. The circuit according to claim 2, characterized in that, The grayscale reference voltage selector includes: There are n selection switches, wherein the selection switches are used to select a set as the target grayscale reference voltage from n dynamic display grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n static display grayscale reference voltages according to a first control signal and a second control signal.

4. The circuit according to claim 2, characterized in that, The difference between the static display analog voltage and the common electrode voltage of the liquid crystal screen is between the first liquid crystal voltage and the second liquid crystal voltage, wherein the liquid crystal screen is in a static display state when it is between the first liquid crystal voltage and the second liquid crystal voltage; The difference between the dynamic display analog voltage and the common electrode voltage is between the third liquid crystal voltage and the fourth liquid crystal voltage, wherein the liquid crystal screen is in a dynamic display state when it is between the third liquid crystal voltage and the fourth liquid crystal voltage; The difference between the simulated voltage of the inserted black frame and the voltage of the common electrode is the fourth liquid crystal voltage; The difference between the zero-level analog voltage and the common electrode voltage is the fifth liquid crystal voltage.

5. The circuit according to claim 1, characterized in that, Also includes: A grayscale reference voltage selection controller is used to send control signals to the grayscale reference voltage selector; The grayscale reference voltage selector is also used to select one set as the target grayscale reference voltage from at least two sets of grayscale reference voltages according to the control signal.

6. The circuit according to claim 1, characterized in that, Also includes: The LCD screen source driving circuit is used to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the LCD screen.

7. A liquid crystal display device, characterized in that, Includes the voltage switching circuit as described in any one of claims 1 to 6.

8. The liquid crystal display device according to claim 7, characterized in that, It also includes the LCD screen source drive circuit and the LCD screen; The LCD screen source driving circuit is used to receive the target grayscale reference voltage from the grayscale reference voltage selector and input the target grayscale reference voltage to the LCD screen.

9. The liquid crystal display device according to claim 8, characterized in that, The LCD screen includes a cholesteric LCD screen.

10. A voltage switching method, characterized in that, include: At least two sets of grayscale reference voltages are generated by resistor voltage division; Choose one of at least two sets of grayscale reference voltages as the target grayscale reference voltage.

11. The method according to claim 10, characterized in that, At least two sets of grayscale reference voltages are generated by resistor voltage division, including: Based on the dynamically displayed analog voltage and the dynamically displayed voltage divider resistor, n dynamically displayed grayscale reference voltages are generated to serve as one set of grayscale reference voltages, where n is an integer greater than 1; n grayscale reference voltages for inserting black frames are generated based on the simulated voltage of the inserted black frame and the voltage divider resistor of the inserted black frame, and used as one set of grayscale reference voltages; n zero-level grayscale reference voltages are generated based on the zero-level analog voltage and the zero-level voltage divider resistor, which will be used as one set of grayscale reference voltages; n static display grayscale reference voltages are generated based on the static display analog voltage and the static display voltage divider resistor, which are used as one set of grayscale reference voltages.

12. The method according to claim 11, characterized in that, Select one set of grayscale reference voltages from at least two sets as the target grayscale reference voltage, including: Based on the first control signal and the second control signal, select one set of n dynamic display grayscale reference voltages, n inserted black frame grayscale reference voltages, n zero-reset grayscale reference voltages, and n static display grayscale reference voltages as n target grayscale reference voltages.

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