Driving device and method of cholesteric liquid crystal passive matrix display panel and electronic paper

Abstract

This invention discloses a driving device, method, and electronic paper for a cholesteric liquid crystal passive matrix display panel, relating to the field of cholesteric liquid crystal display technology. The driving device includes a data driving circuit, a gating driving circuit, and a timing control unit. During line-by-line refresh, within the line refresh cycle of the current scan line, the current scan line and the row window following it, which includes multiple lines to be refreshed, are determined. A first pressure difference is applied to the pixels within the row window to cause the liquid crystal to enter or maintain a focal conic state. Based on the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is bright to cause the liquid crystal to enter or maintain a planar state, and the pixels where the target is dark are placed in a focal conic state, completing the display writing for that line. The pressure difference across the pixels of other lines is made less than a state transition threshold. The row window moves as the current scan line progresses. Each line receives the drive required for the transition to a focal conic state before becoming the current scan line, solving the problem of balancing full-screen refresh speed and display effect.

Description

Technical Field

[0001] This invention relates to the field of cholesteric liquid crystal display technology, and more particularly to a driving device, method, and electronic paper for a cholesteric liquid crystal passive matrix display panel. Background Technology

[0002] As reflective display products such as electronic paper develop towards larger sizes, passive matrix (PM) display panels using cholesteric liquid crystals are becoming increasingly widely used. In this type of panel, pixels do not have thin-film transistors (TFTs). Instead, they are formed by the intersection of vertical data lines (Segment, SEG) and horizontal gating lines (Common, COM). The display state of a pixel is determined by the effective voltage difference between the two lines. When refreshing the panel, each row is typically addressed sequentially, with the data driving circuit and the gating driving circuit working together to establish the target display state for each pixel in the addressed row.

[0003] However, cholesteric liquid crystals require a corresponding driving time to switch from one display state to another. Under the above-mentioned line-by-line addressing refresh method, the more rows there are on the panel, the longer it takes to complete a full-screen refresh. If the driving time that each row can obtain is compressed in order to shorten the full-screen refresh time, the display state of the pixel is not established sufficiently, and the display effect will decrease accordingly.

[0004] Therefore, how to balance full-screen refresh rate and display effect is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a driving device, method, and electronic paper for a cholesteric liquid crystal passive matrix display panel, so as to at least solve the problem that it is difficult to balance full-screen refresh speed and display effect in the line-by-line refresh mode in related technologies.

[0006] To solve the above-mentioned technical problems, the present invention provides a driving device for a cholesteric liquid crystal passive matrix display panel, including a data driving circuit, a gating driving circuit and a timing control unit; The data driving circuit and the gating driving circuit are respectively connected to multiple data signal lines and multiple gating signal lines of the display panel, and the intersection of the data signal lines and the gating signal lines forms a pixel; The timing control unit is connected to the data driving circuit and the gating driving circuit, and is used to drive the corresponding pixel through the potential difference between the data signal line and the gating signal line; The data driving circuit, the gating driving circuit, and the timing control unit are configured to, during the line-by-line refresh process: Determine the current scan line, and the row window that follows the current scan line and includes multiple rows to be refreshed; During the row refresh cycle of the current scan line, in the first precharge phase, a first pressure difference is applied to the pixels in the row window; the first pressure difference causes the cholesteric liquid crystal to enter or remain in a focal conic state, which is a dark display state; In the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in the focal cone state, so as to complete the display writing of the current scan line; the second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state, and the planar state is a bright display state; The pressure difference between the pixels of the current scan line and other lines outside the line window is made less than the display state transition threshold, which is the minimum pressure difference required to change the display state of the cholesteric liquid crystal. The row window moves as the current scan row progresses, so that each row to be refreshed completes the first pre-charge phase before becoming the current scan row.

[0007] To solve the above-mentioned technical problems, the present invention also provides an electronic paper, including a cholesteric liquid crystal passive matrix display panel and a driving device for the cholesteric liquid crystal passive matrix display panel. The display panel includes multiple data signal lines and multiple gating signal lines. The intersection of the data signal lines and the gating signal lines forms a pixel. The cholesteric liquid crystal in the pixel has at least a planar state as a bright display state and a focal conic state as a dark display state. No thin-film transistors are disposed at the pixel of the display panel.

[0008] To address the aforementioned technical problems, this invention also provides a driving method for a cholesteric liquid crystal passive matrix display panel, applied to a driving device for a cholesteric liquid crystal passive matrix display panel including a data driving circuit, a gating driving circuit, and a timing control unit. The data driving circuit and the gating driving circuit are respectively connected to multiple data signal lines and multiple gating signal lines of the display panel, with pixels formed at the intersections of the data signal lines and the gating signal lines. The timing control unit is connected to the data driving circuit and the gating driving circuit, and is used to drive the corresponding pixels through the potential difference between the data signal lines and the gating signal lines. The driving methods for cholesteric liquid crystal passive matrix display panels include: During the line-by-line refresh process: Determine the current scan line, and the row window that follows the current scan line and includes multiple rows to be refreshed; During the row refresh cycle of the current scan line, in the first precharge phase, a first pressure difference is applied to the pixels in the row window; the first pressure difference causes the cholesteric liquid crystal to enter or remain in a focal conic state, which is a dark display state; In the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in the focal cone state, so as to complete the display writing of the current scan line; the second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state, and the planar state is a bright display state; The pressure difference between the pixels of the current scan line and other lines outside the line window is made less than the display state transition threshold, which is the minimum pressure difference required to change the display state of the cholesteric liquid crystal. The row window moves as the current scan row progresses, so that each row to be refreshed completes the first pre-charge phase before becoming the current scan row.

[0009] Through this invention, during the progressive refresh process, in addition to completing the display writing of the current scan line according to the target image data within the line refresh cycle of the current scan line, a first pressure difference is applied to multiple lines to be refreshed within the line window located after the current scan line to enable cholesteric liquid crystal to enter or maintain the focal conic state, and the line window moves with the advancement of the current scan line. This ensures that each line has obtained the drive required for the conversion to the focal conic state before becoming the current scan line. The drive of the lines to be refreshed is completed within the line refresh cycle that the current scan line would originally occupy, without the need to execute the drive and display control line by line. At the same time, for the current scan line and other lines outside the line window, the pressure difference between the two ends of the pixels is controlled below the display state transition threshold, so that the refreshed lines and the lines that have not yet entered the line window maintain their original display state without being affected. Therefore, the problem of difficulty in balancing full-screen refresh speed and display effect under the progressive refresh method in related technologies can be solved, achieving both full-screen refresh speed and good display effect, thereby improving the contrast of the display panel and reducing ghosting. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A schematic diagram of the structure of a driving device for a cholesteric liquid crystal passive matrix display panel provided in an embodiment of the present invention; Figure 2A schematic diagram of the refresh timing process of a cholesteric liquid crystal passive matrix display panel provided in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the relationship between the current scan row and the row window, provided as an embodiment of the present invention. Figure 4 This is a schematic diagram of a drive waveform during the reset phase provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a drive waveform during the holding phase provided in an embodiment of the present invention; Figure 6 A schematic diagram of a driving waveform during the first pre-charge stage provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the driving waveform for a second pre-charge stage provided in an embodiment of the present invention.

[0012] Figure label: 100 - Data drive circuit, 200 - Strobe drive circuit, 300 - Timing control unit. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0014] It should be noted that, in the description of this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first," "second," etc., used in this invention are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0015] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Here, we will first explain some key terms used in the embodiments of the present invention.

[0017] Cholesteric liquid crystal (ChLC) is a liquid crystal material with a helical structure whose molecular arrangement can transition between several states under the influence of an applied electric field. Three states are relevant to this invention: Planar (P-state), where the helical axis of the liquid crystal molecules is approximately perpendicular to the substrate; the liquid crystal layer selectively reflects incident light of a specific wavelength, resulting in a bright pixel display; Focal Conic (FC-state), where the helical axis of the liquid crystal molecules is randomly oriented; incident light passes through the liquid crystal layer and is absorbed by the absorption layer on the back, resulting in a dark pixel display; and Homeotropic (H-state), where the liquid crystal molecules are aligned along the direction of the electric field. This state requires a high electric field strength to exist; after the electric field is removed, the liquid crystal transitions from this state to the planar state. Both the planar and focal conic states can be maintained for a long time after the electric field is removed, a characteristic referred to in the art as bistable.

[0018] A passive matrix (PM) is a pixel addressing method. Display panels using this method do not have active switching devices at the pixel level; instead, two sets of intersecting traces are directly applied with a potential, and the display state of the pixel at that location is determined by the potential difference between the two traces at the intersection. In contrast, an active matrix uses a thin-film transistor as a switch at each pixel.

[0019] Thin-film transistors (TFTs) are devices used as pixel switches in active matrix display panels. Passive matrix display panels do not have this device at the pixel location.

[0020] Data signal lines (Segment, SEG) and gating signal lines (Common, COM) are two intersecting sets of traces in a passive matrix display panel. In this article, the set of traces used to carry pixel data is called the data signal lines, and the set of traces used for row-by-row gating is called the gating signal lines.

[0021] Electronic paper is a type of reflective display product that relies on ambient light rather than a backlight to display images. It consumes virtually no power when the image remains unchanged, making it suitable for applications such as electronic price tags, e-books, and bulletin boards.

[0022] In cholesteric liquid crystal passive matrix display panels, thin-film transistors are not placed at the pixels; the display state of a pixel is determined by the potential difference between the data signal lines and the selection signal lines. When refreshing the panel, each row is selected sequentially in row order. The selected row is the current scan row, and the data driving circuit outputs potential to each data signal line according to the target image data of that row, thereby establishing the required display state on each pixel of that row.

[0023] Cholesteric liquid crystals require a certain driving time to transition from one display state to another. This time is related to the amplitude of the driving voltage difference, the duration of application, and the initial state of the liquid crystal. In the aforementioned line-by-line addressing refresh method, the time it takes for a row of pixels to receive driving is one row refresh cycle for that row to be selected. The more rows the panel has, the longer it takes to complete a full-screen refresh. If the row refresh cycle of each row is compressed to shorten the full-screen refresh time, the pixels in that row will have difficulty fully forming a focal cone state within this short period, resulting in insufficient darkness in dark areas, decreased image contrast, and a tendency for residue from the previous frame to appear.

[0024] To address the challenge of balancing full-screen refresh speed and display quality in progressive refresh methods, this invention provides a driving device, method, and electronic paper for a cholesteric liquid crystal passive matrix display panel. During progressive refresh, in addition to writing the target image data to the current scan line within its refresh cycle, a first pressure differential is applied to multiple lines to be refreshed within the row window following the current scan line, causing the cholesteric liquid crystal to enter or maintain a focal conic state. The row window moves as the current scan line progresses, ensuring that each line has already acquired sufficient display quality before becoming the current scan line. The drive required for the transition to the focal cone state is completed within the row refresh cycle that the current scan row would normally occupy, eliminating the need to execute the drive and display control line by line. At the same time, for the current scan row and other rows outside the row window, the pixel pressure difference is controlled below the display state transition threshold, so that the refreshed rows and rows that have not yet entered the row window maintain their original display state without being affected. Therefore, it can solve the problem of difficulty in balancing full-screen refresh speed and display effect in the line-by-line refresh method in related technologies, combining full-screen refresh speed with good display effect, thereby improving the contrast of the display panel and reducing ghosting.

[0025] First, the driving device for the cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention will be described. The driving device provided in this embodiment of the invention includes at least two circuits that output potentials to two sets of traces of the display panel, and a unit that controls the output timing of these two circuits, thereby establishing the desired display state on the pixels through the potential difference between the two sets of traces.

[0026] Figure 1 This is a schematic diagram of the structure of a driving device for a cholesteric liquid crystal passive matrix display panel provided in an embodiment of the present invention.

[0027] like Figure 1 As shown, the driving device for the cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may include a data driving circuit 100, a gating driving circuit 200, and a timing control unit 300.

[0028] The display panel includes multiple data signal lines and multiple strobe signal lines. Figure 1 The diagram shows five data signal lines (SEG1 to SEG5) and four gating signal lines (COM1 to COM4). The intersections of the data signal lines and the gating signal lines form pixels. Figure 1 In the diagram, circles marked with LC are used to indicate the cholesteric liquid crystal at each intersection position.

[0029] The data driving circuit 100 is connected to each data signal line, the gating driving circuit 200 is connected to each gating signal line, and the timing control unit 300 is connected to the data driving circuit 100 and the gating driving circuit 200 respectively, and is used to drive the corresponding pixel through the potential difference between the data signal line and the gating signal line.

[0030] Figure 1 The number of traces shown is for illustrative purposes only; the number of rows and columns on the display panel can be determined according to product requirements.

[0031] The data driving circuit 100 and the gating driving circuit 200 can be implemented using existing driving chips with multi-level output capability. The timing control unit 300 can be implemented using a field programmable gate array (FPGA), a microcontroller, or timing logic integrated into the driving chip. The present invention does not limit its specific form.

[0032] For ease of explanation, the pressure difference across a pixel will be denoted as in this article. ,in This indicates the electrical potential of the data signal line to which the pixel is connected. This indicates the potential of the gating signal line to which the pixel is connected. VP1, VP2, VP3, VN1, VN2, VN3, and VDM, labeled in the attached diagram, are referred to in this document as... , , , , , and T1 to T8, as indicated in the attached figures, are referred to in this document as follows: to .in, and , and , and The voltages are symmetrical about the same reference potential, meaning that the absolute values ​​of the voltage difference across the pixel are equal in both halves of the same precharge phase, thus causing the DC components of the voltage applied to the pixel to cancel each other out.

[0033] The display state transition threshold in this embodiment of the invention refers to the minimum voltage difference required to change the display state of a cholesteric liquid crystal. This threshold can be obtained through actual measurement and calibration. Specifically, a voltage difference with gradually increasing amplitude is applied to the pixels of the sample panel, and the change in pixel reflectivity is measured. The voltage difference at which the reflectivity begins to change is taken as the threshold. For example, for common cholesteric liquid crystal panels, this threshold is around 5V, and correspondingly, the voltage difference across the pixels of rows that do not require a change in display state can be controlled below 5V.

[0034] In this embodiment of the invention, the data driving circuit 100, the gating driving circuit 200, and the timing control unit 300 are configured to perform the following operations during the line-by-line refresh process: Determine the current scan line, and the row window that follows the current scan line and includes multiple rows to be refreshed; During the row refresh cycle of the current scan line, in the first precharge phase, a first pressure difference is applied to the pixels in the row window; the first pressure difference causes the cholesteric liquid crystal to enter or remain in the focal conic state, which is a dark display state; In the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in a focal conic state, so as to complete the display writing of the current scan line; the second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state, and the planar state is the bright state display state; Make the voltage difference between the two ends of the pixels in the current scan line and other lines outside the line window less than the display state transition threshold, which is the minimum voltage difference required to change the display state of the cholesteric liquid crystal. The row window moves as the current scan row progresses, so that each row to be refreshed completes the first pre-charge phase before becoming the current scan row.

[0035] Figure 2 This is a schematic diagram of the refresh timing process of a cholesteric liquid crystal passive matrix display panel provided in an embodiment of the present invention.

[0036] like Figure 2 As shown, a single refresh process proceeds in the following order: reset phase, hold phase, first pre-charge phase, second pre-charge phase, and hold phase. The first pre-charge phase cycles N1 times, and the second pre-charge phase cycles N2 times. Figure 2 The corresponding terms are labeled as the first pre-charge stage (N1 cycles) and the second pre-charge stage (N2 cycles). It should be noted that... Figure 2 The order shown refers to any row of pixels in the panel, meaning that the pixels in that row go through the above stages in sequence during a single refresh.

[0037] Figure 3 This is a schematic diagram illustrating the relationship between the current scan row and the row window, provided as an embodiment of the present invention.

[0038] like Figure 3 As shown, Figure 3 The upper left corner indicates the current refresh cycle, and the upper right corner indicates preparation for the next cycle. The former corresponds to the display writing of the current scanned row, and the latter corresponds to the preprocessing to be done for subsequent rows. Figure 3 The images, from top to bottom, show the state of several rows of pixels at the same time. The right side is labeled as row (n-1), row n (current row), row (n+a), row (n+a+1), row (n+a+2), and row (n+a+b), where 'a' represents the row offset of the starting row of the row window relative to the current scan row. Row n is the current scan row, and the corresponding box is labeled as the second pre-charge stage: the current row is completed after the loop ends, meaning the row is displayed after each loop in the second pre-charge stage. Rows n+a to n+a+2 are located within the row window. Figure 3 The parentheses on the right represent the row windows. The boxes corresponding to these rows are all marked as the first pre-charge stage: pre-brushing, which means that the driving force for the liquid crystal to switch to the focal cone state is applied to the pixels of these rows in advance. The (n-1)th row is the row that has completed the display write, and the (n+a+b)th row is the row that has not yet entered the row window. The boxes corresponding to both are marked as the hold stage: state unchanged, that is, the display state of these rows does not change during this period. Figure 3 The two ellipses indicate that more rows can be included between the current scan line and the starting line of the row window, as well as within the row window itself.

[0039] It should be noted that, Figure 2 and Figure 3 It describes two aspects of the same refresh process. Figure 2 It describes the stages that a row of pixels goes through sequentially over time. Figure 3 This describes that at the same moment, different rows in the panel are in different stages, and the two are not contradictory.

[0040] The starting line of the row window can be the first line after the current scan line, or it can be more than one line apart from the current scan line. That is, 'a' can be 1 or an integer greater than 1. For example, if 'a' is 2, and the current scan line is the nth line, the row window will contain lines from the (n+2)th line to the (n+50)th line. The number of lines to be refreshed contained in the row window can be determined according to the number of lines on the display panel and the refresh requirements, for example, from a few lines to dozens of lines.

[0041] Since both the first and second pre-charge phases are executed within the current scan line's refresh cycle, each row of pixels has already accumulated the drive required for the focal cone state transition over multiple previous refresh cycles before becoming the current scan line. Therefore, the formation of the focal cone state is no longer limited to the single refresh cycle in which the row is selected. The number of first pre-charge phases accumulated for each row to be refreshed is the product of the number of refresh cycles during its stay within the row window and the number of cycles of the first pre-charge phase within each refresh cycle. Each refresh cycle only needs to accommodate the latter, thus distributing the focal cone state drive required for a single row across multiple refresh cycles. In this way, while ensuring each row receives the same amount of drive, the total full-screen refresh time is significantly shorter than when all drives are completed within each row's own refresh cycle. The dark states of each row's pixels are formed more fully, improving the contrast of the display panel and reducing the amount of residual previous frame data. Simultaneously, the pixel voltage difference between the current scan line and other rows outside the row window is less than the display state transition threshold, so the display state of rows that have already been refreshed and those that have not yet entered the row window remains unchanged.

[0042] To eliminate the residue from the previous frame, all pixels on the display panel can be brought to a uniform initial display state before the progressive refresh process begins; during periods when the pixel display state does not need to be changed, the pressure difference between the two ends of the pixel should be small enough.

[0043] In this embodiment of the invention, the data driving circuit 100, the gating driving circuit 200, and the timing control unit 300 are further configured to sequentially execute a reset phase and a hold phase before the line-by-line refresh process. During the reset phase, potentials of opposite polarities are simultaneously output to all data signal lines and all gating signal lines, creating a third voltage difference across each pixel of the display panel. This third voltage difference causes the cholesteric liquid crystal to enter a vertical state. After the application of the third voltage difference ends, the output potential is changed, causing the cholesteric liquid crystal of each pixel to transition from a vertical state to a planar state. During the hold phase, the voltage difference across each pixel is made less than the display state transition threshold.

[0044] Figure 4 This is a schematic diagram of the driving waveform during the reset phase provided in an embodiment of the present invention.

[0045] like Figure 4 As shown, Figure 4 The box above indicates the reset phase. Figure 4 The legend on the right labels the data signal lines and the strobe signal lines, corresponding to the two waveform curves in the diagram. In the first... During the time period, the potential of the data signal line is The potential of the strobe signal line is , Figure 4 The corresponding labels are VP3 T1 and VN3 T1; in the second During the time period, the potentials of the two traces are swapped, and the potential of the data signal line is... The potential of the strobe signal line is , Figure 4 The corresponding labels are VN3 T1 and VP3 T1; in the subsequent... During the period, the potential of both traces was [missing information]. , Figure 4 The label is VDM T2.

[0046] In the above two During the specified time period, the third voltage difference across the pixels exceeds the vertical driving threshold voltage, causing the liquid crystal to enter the vertical state, thus resetting the entire screen. For example, the third voltage difference is greater than 30V, such as 35V. During the specified time period, the potentials of the two traces are the same, the voltage difference across the pixel drops to zero, the liquid crystal transitions from a vertical state to a planar state, and the entire screen displays a bright state. The opposite polarity of the time periods ensures that the voltage applied to the pixel during the reset phase is roughly balanced in the positive and negative directions, which helps to reduce DC bias.

[0047] Figure 5 This is a schematic diagram of a driving waveform during the holding phase, provided as an embodiment of the present invention.

[0048] like Figure 5 As shown, Figure 5 The box above is marked as the holding phase. Figure 5 The diagram on the right shows the data signal lines and the strobe signal lines. The potentials of the data signal lines are as follows: , , and Their durations are as follows: , , and , Figure 5 The corresponding values ​​are labeled VP1 T6, VP3 T5, VN3 T5, and VN1 T6; the potential of the strobe signal line in the first half of the stroke is... The potential in the second half is The duration of both is equal to and the sum of Figure 5 The corresponding labels are VP2T5+T6 and VN2 T5+T6.

[0049] because lie in and between, lie in and During the hold phase, the voltage difference across the pixel remains small at each time point, below the display state transition threshold (e.g., less than 5V), thus maintaining the pixel's display state. The current scan line and other lines outside the line window also remain in this hold state during line-by-line refresh.

[0050] Depend on Figure 4 and Figure 5 It can be seen that the gating drive circuit 200 can selectively output a first level, a second level, and a third level to the gating signal line, with the second level located between the first level and the third level. For example, the first level is... The third level is The second level is .

[0051] In this embodiment of the invention, the second voltage difference is greater than the focal conic state driving threshold voltage and less than the vertical state driving threshold voltage, and the third voltage difference is greater than the vertical state driving threshold voltage; the focal conic state driving threshold voltage and the vertical state driving threshold voltage are the driving threshold voltages corresponding to the cholesteric liquid crystal switching into the focal conic state and the vertical state, respectively; in the second pre-charge stage, a fourth voltage difference is applied to the pixels in the current scan line whose target is the dark state, and the fourth voltage difference corresponds to the focal conic state driving threshold voltage.

[0052] In this paper, the driving threshold voltage corresponding to the transition of cholesteric liquid crystal to the focal conic state is denoted as . The driving threshold voltage that causes the cholesteric liquid crystal to transition to the vertical state is denoted as . Both can be obtained through actual measurement and calibration, and the calibration method is the same as the display state transition threshold. Therefore, the third pressure difference is greater than... It should be noted that, and The specific values ​​depend on the liquid crystal material, cell thickness, and the duration of the applied voltage difference, and are not fixed. Since applying a voltage difference of 5V to 20V is sufficient to induce the liquid crystal into the focal conic state, and a second voltage difference greater than 25V is required to induce the liquid crystal into the planar state, therefore... Below 20V, Above 25V.

[0053] In this embodiment of the invention, the function of the first pre-charge stage is to apply a drive to the pixels of the row to be refreshed before the row becomes the current scan row, so that the dark state of the row has been formed to the required degree when it becomes the current scan row.

[0054] Figure 6 This is a schematic diagram of the driving waveform for the first pre-charge stage provided in an embodiment of the present invention.

[0055] like Figure 6 As shown, Figure 6 The box at the top indicates the first pre-charging stage. Figure 6 The diagram on the right shows the data signal lines and the strobe signal lines. The potentials of the data signal lines are as follows: , , and Their durations are as follows: , , and , Figure 6 The corresponding values ​​are labeled VP1 T6, VP3 T5, VN3 T5, and VN1 T6. The potential of the strobe signal line is initially [value missing] in the first half of the signal path. The duration is and Sum minus Subsequently During the period of time, it dropped to In the second half of the race, first for The duration is It was subsequently restored to The duration is also and Sum minus , Figure 6 The corresponding labels are VDM T5+T6-T8, VN1 T8, VP1 T8, and VDM T5+T6-T8.

[0056] Depend on Figure 6 It can be seen that the duration of both the first and second halves is equal to and The sum, the gating signal line has one at the end of the first half and one at the beginning of the second half. These two time periods are respectively located when the data signal line is in and Within a certain time period, and symmetrical with respect to the reversal time between half-courses.

[0057] In this embodiment of the invention, the first pre-charge stage may include a first time period and a second time period executed sequentially. During the first time period, a first pressure difference is applied to the pixels within the row window, and during the second time period, a fifth pressure difference is applied to the pixels within the row window. The fifth pressure difference is greater than the first pressure difference, and the duration of the second time period is less than the duration of the first time period. Combined with... Figure 6 Taking the first half of the process as an example, the first period is when the data signal line is in... The gating signal line is in of During the first time period, a first voltage difference is formed across the two ends of the pixel; the second time period is when the data signal line is in... of During this period, a fifth voltage difference is formed across the pixels. For example, the first voltage difference is 5V to 20V, and the fifth voltage difference is greater than 20V. The second half of the process is symmetrical, except that the polarities of the potentials are reversed.

[0058] Applying a larger fifth voltage difference during the shorter second time period can accelerate the liquid crystal's departure from its original state, while applying a first voltage difference during the longer first time period allows the focal cone state to be formed. The combination of these two methods improves the formation degree of the dark state without prolonging the total duration of the first pre-charge stage.

[0059] In some optional embodiments of the present invention, the second time period may further include a period of duration of During the specified time period, the potential of the strobe signal line corresponding to each row to be refreshed within the row window changes from... Become The potential of the data signal line remains at 0. The voltage remains unchanged, thus further increasing the voltage difference across the pixel. In the second half of the process, this... The potential of the gating signal line during the time period is changed from Become The potential of the data signal line remains at 0. The voltage difference across the pixel remains unchanged, and its polarity is reversed compared to the first half. Thus, this further increase in voltage difference is provided by the gating signal line, eliminating the need for the data drive circuit 100 to add different output levels, and the two... The time interval is symmetrical with respect to the commutation time between half-cycles, and no additional DC component is introduced.

[0060] It should be noted that, Used to specify The time width equals and The sum of the time widths is equal to and the sum of to There are no exact values; they vary depending on the display panel. The lengths of the various time periods shown in the attached diagram are for illustrative purposes only.

[0061] In embodiments of the invention, the gating drive circuit can be configured to selectively output a first level, a second level, and a third level to the gating signal lines, with the second level located between the first and third levels. During the first pre-charge phase, the gating signal lines corresponding to each row to be refreshed within the row window are applied with the second level. During the second pre-charge phase, the gating signal lines corresponding to the currently scanned row are applied with either the first or the third level. In embodiments without the additional driving period provided later, the gating signal lines corresponding to each row to be refreshed within the row window remain at the second level throughout the entire first pre-charge phase. In embodiments employing the additional driving period, the gating signal lines switch to other levels during this period, based on the second level.

[0062] Combination Figure 6 The second level is Since the second level is located between the first and third levels, the voltage difference formed at both ends of the pixel within the row window is between the voltage difference during the holding phase and the voltage difference required for writing the planar state. This voltage difference causes the liquid crystal to enter or hold the focal cone state.

[0063] In this embodiment of the invention, the data driving circuit, the gating driving circuit, and the timing control unit can also be configured to: cause the current scan row to undergo N2 second pre-charge stages within the row refresh cycle to complete the display writing of the current scan row; cause each row to be refreshed to undergo a cumulative N1 first pre-charge stages during the period it is located within the row window; wherein N1 and N2 are both positive integers.

[0064] The value of N1 can be determined according to the load and refresh requirements of the display panel. It should be noted that N1 is not always better the larger it is. When N1 increases, dark scenes become darker and the contrast of the display panel is higher. However, when N1 increases to a certain extent, the dark scenes of pixels no longer change accordingly, and the contrast no longer improves significantly. At the same time, since the first precharge stage is executed within the row refresh cycle of the current scan line, changing the value of N1 will not significantly change the total duration of the full-screen refresh.

[0065] In this embodiment of the invention, the first pre-charge stage may include a first half and a second half with opposite polarities, and the second pre-charge stage may include a third half and a fourth half with opposite polarities; in the first half and the third half, the potential of the data signal line is higher than the potential of the corresponding gating signal line; in the second half and the fourth half, the potential of the data signal line is lower than the potential of the corresponding gating signal line; in the two halves of the same pre-charge stage, the absolute value of the voltage difference between the two ends of the pixel is equal and the duration is the same.

[0066] In this way, a polarity reversal is completed within each first pre-charge stage, and the DC components of the voltage applied to the pixel cancel each other out in this stage, reducing the charge accumulation of the liquid crystal material and the alignment layer, which helps to reduce image retention and improve reliability.

[0067] In the first pre-charge stage, the first voltage difference applied to the pixels within the row window is independent of the target image data of the pixels within that row window. Pixels with a bright target and pixels with a dark target within the row window are subjected to the same first voltage difference. The reason for this is that when preprocessing subsequent rows, the first pre-charge stage and the display write of the current scan row share the same set of data signal line potentials. It is difficult to set the voltage difference separately according to the target image data of each row to be refreshed. Furthermore, distinguishing the target image row by row requires the timing control unit 300 to pre-parse the data of multiple subsequent rows. Therefore, the first pre-charge stage does not distinguish whether the target image is bright or dark, and uniformly puts the pixels into the focal cone state. The image differentiation processing is concentrated in the second pre-charge stage.

[0068] There are two ways to implement the above processing. First, the first pre-charge stage occupies a dedicated time slot. During this time, the data driving circuit 100 outputs the same potential to all data signal lines, creating the same first voltage difference across each pixel within the row window. Second, the first pre-charge stage shares the same set of data signal line potentials with the display write of the current scan line. In this case, the strobe signal lines corresponding to each row to be refreshed within the row window are unified to the second level, ensuring that when the data signal lines are at any potential, the voltage difference across each pixel within the row window causes the liquid crystal to switch to a focal cone state. Using either of these methods, there is no need to parse the target image data of subsequent multiple lines during preprocessing, simplifying the processing of the timing control unit 300.

[0069] In some optional embodiments of the present invention, as the row window moves line by line with the current scan line, the number of times the line to be refreshed that enters the row window first has accumulated the first pre-charge stage at any given time is greater than that of the line to be refreshed that enters the row window later. That is, in each row refresh cycle, each line to be refreshed within the row window synchronously undergoes the first pre-charge stage. At any given time, the closer the line to be refreshed is to the current scan line, the more drive it has accumulated for the conversion to the focal cone state. The number of first pre-charge stages accumulated by each line to be refreshed when leaving the row window is the same. In this way, before each line to be refreshed moves to the position of the current scan line, the degree of focal cone state formation increases line by line, and by the time it becomes the current scan line, it has reached the required degree, so it is not necessary to supplement the drive time within its own row refresh cycle.

[0070] In this embodiment of the invention, the function of the second pre-charging stage is to distinguish between pixels in the current scan row that are in a bright state and pixels in the current scan row that are in a dark state, so that the pixels in the row reach the display state corresponding to the target image data.

[0071] Figure 7 This is a schematic diagram of the driving waveform for a second pre-charge stage provided in an embodiment of the present invention.

[0072] like Figure 7 As shown, Figure 7 The box above indicates the second pre-charge stage. Figure 7 The legend on the right labels the data signal line (data potential of the target bright pixel), the data signal line (data potential of the target dark pixel), and the gating signal line, with the first two corresponding to the solid and dashed lines in the diagram, respectively. The potential of the gating signal line in the first half is... The potential in the second half is The duration of both is equal to and the sum of Figure 7 The corresponding labels are VN3 T5+T6 and VP3T5+T6. The data potentials of the target bright-state pixels are as follows: , , and Their durations are as follows: , , and , Figure 7 The corresponding values ​​are labeled VP1 T6, VP3 T5, VN3 T5, and VN1 T6; the data potential of the target dark-state pixels remains constant in the first half of the process. Maintaining this level in the second half of the race Their duration is equal to and sum.

[0073] Depend on Figure 7 It can be seen that when the data signal line is in of During the time period, the pressure difference across the target bright pixel is greater than the pressure difference across the target dark pixel, thus distinguishing the two types of pixels; during other time periods, the pressure difference across the two types of pixels is the same.

[0074] As described in the above embodiments, during the second pre-charge stage, the gating signal line corresponding to the current scan line is applied with a first level or a third level. Since the first level and the third level are the lowest and highest output levels of the gating signal line, respectively, a voltage difference sufficient to cause the liquid crystal to enter a planar state can be formed across the pixels of the current scan line, while the gating signal lines of other lines remain at the second level or the hold level, and the voltage difference across their pixels is insufficient to change the display state.

[0075] As described in the above embodiments, the second pressure difference is greater than and less than The second pressure difference is greater than Therefore, it enables the pixel to escape the focal cone state formed in the first precharge stage; the second pressure difference is less than Therefore, the pixel will not be mistakenly reset to a vertical state. For example, the second voltage difference is greater than 25V.

[0076] For pixels in the current scan line where the target is dark, there are two implementation methods. One is to apply a fourth pressure difference to the pixel, the fourth pressure difference being... Correspondingly, this keeps the pixel in the focal cone state, combined with Figure 7 The voltage difference is formed by the data potential of the target dark pixel and the potential of the gating signal line. Secondly, if no voltage difference is applied to the pixel to change its display state, the pixel maintains the focal cone state already formed in the first pre-charge stage. When the first method is used, the dark pixel is further driven in the second pre-charge stage, resulting in a more complete dark state and a correspondingly improved black-and-white contrast.

[0077] The current scan line undergoes N2 second precharge phases within the line refresh cycle to complete the display writing of the current scan line, where N2 is a positive integer. The cumulative driving force applied during the N2 second precharge phases enables the pixels of the current scan line to reach the display state corresponding to the target image data; it is not only the last phase that performs the writing function. N1 and N2 can take different values ​​and can be set separately. Similar to N1, as N2 increases, the bright state of the image becomes brighter, and the contrast of the display panel is higher. When N2 increases to a certain extent, the display state of the pixels no longer changes accordingly, and the contrast no longer improves significantly. N1 and N2 are set according to the desired formation level of the target dark state and the target bright state, respectively.

[0078] The second precharge phase includes a third and fourth half-pass with opposite polarities, and their potential relationships are the same as the two half-passes of the first precharge phase.

[0079] In some optional embodiments of the present invention, during the second pre-charge stage, the gating signal line corresponding to the current scan line is applied with a third level and a first level in the third and fourth halves of the stroke, respectively, so that the write voltage difference formed at both ends of the pixel is greater than the potential swing of the data signal line or the gating signal line relative to the intermediate level. Thus, the voltage difference required for writing the planar state is provided by the potentials of opposite polarities on the two traces, and neither the data driving circuit 100 nor the gating driving circuit 200 needs to have an output voltage range covering the entire write voltage difference.

[0080] The time required for liquid crystal to form a focal cone state varies depending on the operating conditions of the display panel. Therefore, the position and width of the row window do not need to be fixed and can be adjusted according to the operating conditions.

[0081] In this embodiment of the invention, the timing control unit can also be used to obtain the working state of the display panel, and determine at least one of the following based on the working state: the row offset of the starting row of the row window relative to the current scan row, the number of rows to be refreshed contained in the row window, and the number of cycles of the first precharge stage; the working state includes at least one of the load of the display panel, the temperature of the display panel, and the refresh target, so that the cumulative number of the first precharge stages experienced by the row to be refreshed before becoming the current scan row is adapted to the working state.

[0082] Typically, as temperature decreases, the liquid crystal's response slows down, and the driving time required for a row of pixels to form a focal cone state increases. When the panel load increases, the signal setup time on the traces lengthens, the effective voltage difference actually applied to the pixels decreases, and the required driving time also increases. In these cases, the starting line offset of the line window or the number of lines to be refreshed contained in the line window can be increased, allowing the lines to be refreshed to enter the line window earlier and undergo more first pre-charge stages. Conversely, at higher temperatures or lighter loads, the line offset or the number of lines can be decreased. The time required for the liquid crystal to form a focal cone state is thus converted into the number of lines of the line to be refreshed relative to the current scan line.

[0083] In some optional embodiments of the present invention, a mapping relationship between temperature range, panel load, and row window parameters can be pre-established and stored in the timing control unit 300. During runtime, the starting row offset and the number of rows to be refreshed in the row window are obtained by looking up the table according to the current working state. For example, the temperature is divided into a first temperature range, a second temperature range, and a third temperature range. The temperature in the first temperature range is lower than the temperature in the second temperature range, and the temperature in the second temperature range is lower than the temperature in the third temperature range. A larger row offset and a larger number of rows are used in the first temperature range, and a smaller row offset and a smaller number of rows are used in the second temperature range. The specific values ​​in the above mapping relationship can be calibrated by measuring the degree of dark state formation on the sample panel at different temperatures. Furthermore, different number of cycles for the first pre-charge stage and the second pre-charge stage can be set according to different temperature ranges.

[0084] In this embodiment of the invention, the temperature of the display panel can be measured by a temperature sensing element located near the display panel, or by a temperature sensing function inside the driver chip; the load on the display panel can be determined by the number of rows, columns, and trace impedance of the panel; the refresh target can be determined by the type of image to be displayed and the required refresh rate. When the requirements for the degree of dark state formation or contrast are increased, the number of cycles in the first precharge stage and / or the number of rows to be refreshed contained in the row window can be increased; when the requirements for the degree of dark state formation are decreased, the number of cycles in the first precharge stage and / or the number of rows to be refreshed contained in the row window can be reduced accordingly.

[0085] In some optional embodiments of the present invention, the number of cycles for the first pre-charge stage and the number of cycles for the second pre-charge stage can be set separately. Specifically, the number of cycles for the first pre-charge stage can be set according to the desired dark state formation level for pixels targeting a dark state. As this number increases, the dark state image becomes darker, and the contrast of the display panel becomes higher. After increasing to a certain extent, the contrast no longer shows significant improvement. Similarly, the number of cycles for the second pre-charge stage can be set according to the desired bright state formation level for pixels targeting a bright state. As this number increases, the bright state image becomes brighter, and the contrast of the display panel becomes higher. After increasing to a certain extent, the contrast also no longer shows significant improvement. The values ​​of both can be obtained through actual measurement and calibration of sample panels.

[0086] In this embodiment of the invention, both the first pre-charge stage and the second pre-charge stage can be turned on or off independently, and N1 and N2 can be set separately. For example, when the screen content is relatively simple or when a high refresh rate is required, one of the stages can be turned off or its cycle count can be reduced. It should be noted that turning off the second pre-charge stage is applicable when the target display state of the current scan line is the same as its existing display state, or when the target image of the line is entirely dark and the target display state has been achieved after the first pre-charge stage.

[0087] In this embodiment of the invention, the polarity of each differential pressure can be alternated between adjacent refresh processes to further reduce DC bias.

[0088] The driving device for the cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention can be implemented using an existing driving chip with multi-level output capability. Thin film transistors do not need to be set at the pixels of the display panel, so it is suitable for low-cost, large-area display products.

[0089] This invention also provides an electronic paper, which may include a cholesteric liquid crystal passive matrix display panel and a driving device for the cholesteric liquid crystal passive matrix display panel provided in any of the above embodiments. The display panel includes multiple data signal lines and multiple selection signal lines, and the intersection of the data signal lines and the selection signal lines forms a pixel. The cholesteric liquid crystal in the pixel has at least a planar state as a bright display state and a focal conic state as a dark display state, and no thin-film transistors are disposed at the pixel of the display panel.

[0090] This electronic paper displays images using ambient light and consumes virtually no power when the image remains unchanged. It can be used for electronic price tags, e-books, bulletin boards, and other applications.

[0091] This invention also provides a driving method for a cholesteric liquid crystal passive matrix display panel, which can be applied to the driving device for the cholesteric liquid crystal passive matrix display panel provided in any of the above embodiments. The meanings of the terms used in the method are the same as in the above embodiments, and will not be repeated here.

[0092] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention performs the following steps during the line-by-line refresh process.

[0093] Step 1: Determine the current scan line and the row window that follows the current scan line and includes multiple rows to be refreshed.

[0094] Step 2: During the row refresh cycle of the current scan line, in the first pre-charge stage, a first pressure difference is applied to the pixels in the row window, and the first pressure difference causes the cholesteric liquid crystal to enter or remain in the focal conic state.

[0095] Step 3, in the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in a focal conic state to complete the display writing of the current scan line. The second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state.

[0096] Step 4: Make the pixel pressure difference between the current scan line and other lines outside the line window less than the display state transition threshold.

[0097] Step 5: Move the row window as the current scan row progresses, so that each row to be refreshed completes the first pre-filling stage before becoming the current scan row.

[0098] In steps one through five above, steps two and three are executed within the same row refresh cycle, step four targets the current scanned row and rows outside the row window, and step five is executed after the current scanned row has finished displaying and writing.

[0099] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: causing the current scan line to undergo N2 second pre-charge stages within the line refresh cycle, and causing each line to be refreshed to undergo a cumulative N1 first pre-charge stages while located within the line window, where N1 and N2 are both positive integers. For specific implementation details, please refer to the description in the driving device embodiment.

[0100] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: selectively outputting a first level, a second level, or a third level to the gating signal lines, wherein the second level is located between the first level and the third level; applying the second level to the gating signal lines corresponding to each row to be refreshed within the row window during a first pre-charge phase; and applying the first level or the third level to the gating signal lines corresponding to the current scan row during a second pre-charge phase. For specific implementation details, please refer to the description in the driving device embodiment.

[0101] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: sequentially executing a reset phase and a hold phase before the line-by-line refresh process; in the reset phase, forming a third pressure difference across each pixel to cause the liquid crystal to enter a vertical state, and subsequently causing the liquid crystal to transition from the vertical state to a planar state; and in the hold phase, ensuring that the pressure difference across each pixel is less than a display state transition threshold. For specific implementation details, please refer to the description in the driving device embodiment.

[0102] The driving method for the cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: making the second pressure difference greater than 1 / 2. and less than This makes the third pressure difference greater than And apply an AND to the pixels in the current scan row that are in a dark state. The corresponding fourth pressure difference. For details on its implementation, please refer to the description in the embodiment of the drive device.

[0103] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: ensuring that the first pre-charge stage and the second pre-charge stage each comprise two halves of opposite polarity, wherein the absolute values ​​of the voltage differences across the pixels in the two halves of the same pre-charge stage are equal and their durations are the same. For specific implementation details, please refer to the description in the driving device embodiment.

[0104] The driving method for the cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: making the first pre-charge stage include a first time period and a second time period executed sequentially, applying a first pressure difference in the first time period, applying a fifth pressure difference greater than the first pressure difference in the second time period, and the duration of the second time period being shorter than the duration of the first time period. For specific implementation details, please refer to the description in the driving device embodiment.

[0105] The driving method for a cholesteric liquid crystal passive matrix display panel provided in this embodiment of the invention may further include: acquiring the working state of the display panel, and determining, based on the working state, at least one of the following: the row offset of the starting row of the row window relative to the current scan row, the number of rows to be refreshed contained in the row window, and the number of cycles in the first pre-charge stage. For specific implementation details, please refer to the description in the driving device embodiment.

[0106] This invention also provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to execute the steps in any of the above-described embodiments of the driving method for a cholesteric liquid crystal passive matrix display panel. This electronic device can be the aforementioned driving device or an electronic paper device including the aforementioned driving device, and the processor can be implemented by a timing control unit 300.

[0107] This invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, can implement the steps of the driving method for a cholesteric liquid crystal passive matrix display panel as provided in any of the above embodiments.

[0108] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0109] For a description of the computer-readable storage medium provided in the embodiments of the present invention, please refer to the above method embodiments. The effects it achieves are the same as those of the driving method for the cholesteric liquid crystal passive matrix display panel provided in the embodiments of the present invention, and will not be repeated here.

[0110] This invention provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the driving method for a cholesteric liquid crystal passive matrix display panel as provided in any of the above embodiments.

[0111] For a description of the computer program product provided in the embodiments of the present invention, please refer to the above method embodiments. The effects it achieves are the same as the driving method of the cholesteric liquid crystal passive matrix display panel provided in the embodiments of the present invention, and will not be described again here.

[0112] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0113] The driving device, method, and electronic paper for the cholesteric liquid crystal passive matrix display panel provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only intended to help understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A driving device for a cholesteric liquid crystal passive matrix display panel, characterized in that, Includes data driving circuitry, gating driving circuitry, and timing control unit; The data driving circuit and the gating driving circuit are respectively connected to multiple data signal lines and multiple gating signal lines of the display panel, and the intersection of the data signal lines and the gating signal lines forms a pixel; The timing control unit is connected to the data driving circuit and the gating driving circuit, and is used to drive the corresponding pixel through the potential difference between the data signal line and the gating signal line; The data driving circuit, the gating driving circuit, and the timing control unit are configured to, during the line-by-line refresh process: Determine the current scan line, and the row window that follows the current scan line and includes multiple rows to be refreshed; During the row refresh cycle of the current scan line, in the first precharge phase, a first pressure difference is applied to the pixels in the row window; the first pressure difference causes the cholesteric liquid crystal to enter or remain in a focal conic state, which is a dark display state; In the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in the focal cone state, so as to complete the display writing of the current scan line; the second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state, and the planar state is a bright display state; The pressure difference between the pixels of the current scan line and other lines outside the line window is made less than the display state transition threshold, which is the minimum pressure difference required to change the display state of the cholesteric liquid crystal. The row window moves as the current scan row progresses, so that each row to be refreshed completes the first pre-charge phase before becoming the current scan row.

2. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 1, characterized in that, The data driving circuit, the gating driving circuit, and the timing control unit are further configured to: The current scan line undergoes N2 second pre-charge phases within the line refresh cycle to complete the display writing of the current scan line; Each row to be refreshed undergoes the first pre-charge phase N1 times during the period it is within the row window; Where N1 and N2 are both positive integers.

3. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 1, characterized in that, The gating drive circuit is configured to selectively output a first level, a second level, and a third level to the gating signal line, wherein the second level is located between the first level and the third level; During the first pre-charge phase, the strobe signal line corresponding to each row to be refreshed within the row window is applied with the second level; During the second precharge phase, the strobe signal line corresponding to the current scan line is applied with either the first level or the third level.

4. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 1, characterized in that, The data driving circuit, the gating driving circuit, and the timing control unit are further configured to sequentially execute a reset phase and a hold phase before the line-by-line refresh process. During the reset phase, potentials of opposite polarities are simultaneously output to all data signal lines and all gating signal lines, creating a third voltage difference across each pixel of the display panel. This third voltage difference causes the cholesteric liquid crystal to enter a vertical state. After the application of the third voltage difference ends, the output potential is changed, causing the cholesteric liquid crystal of each pixel to transition from the vertical state to the planar state. During the holding phase, the pressure difference across each pixel is made less than the display state transition threshold.

5. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 4, characterized in that, The second voltage difference is greater than the focal conic state driving threshold voltage and less than the vertical state driving threshold voltage, and the third voltage difference is greater than the vertical state driving threshold voltage; the focal conic state driving threshold voltage and the vertical state driving threshold voltage are the driving threshold voltages corresponding to the cholesteric liquid crystal switching into the focal conic state and the vertical state, respectively; In the second pre-charge phase, a fourth voltage difference is applied to the pixels in the current scan line that are in a dark state, the fourth voltage difference corresponding to the focal cone state drive threshold voltage.

6. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 5, characterized in that, The first precharge phase includes a first half and a second half with opposite polarities, and the second precharge phase includes a third half and a fourth half with opposite polarities. In the first half-range and the third half-range, the potential of the data signal line is higher than the potential of the corresponding gating signal line; in the second half-range and the fourth half-range, the potential of the data signal line is lower than the potential of the corresponding gating signal line. In the two halves of the same precharge phase, the absolute value of the voltage difference at both ends of the pixel is equal and the duration is the same.

7. The driving device for a cholesteric liquid crystal passive matrix display panel according to claim 4 or 5, characterized in that, The first pre-charge phase includes a first time period and a second time period executed sequentially; During the first time period, the first pressure difference is applied to the pixels within the row window; During the second time period, a fifth pressure differential is applied to the pixels within the row window; The fifth pressure difference is greater than the first pressure difference, and the duration of the second time period is less than the duration of the first time period.

8. The driving device for the cholesteric liquid crystal passive matrix display panel according to claim 1, characterized in that, The timing control unit is also used to acquire the working state of the display panel, and determine at least one of the following based on the working state: the row offset of the starting row of the row window relative to the current scan row, the number of rows to be refreshed contained in the row window, and the number of cycles in the first precharge stage. The operating state includes at least one of the load of the display panel, the temperature of the display panel, and the refresh target, so that the cumulative number of the first precharge phases experienced by the row to be refreshed before becoming the current scan row is adapted to the operating state.

9. An electronic paper, characterized in that, The invention includes a cholesteric liquid crystal passive matrix display panel and a driving device for the cholesteric liquid crystal passive matrix display panel according to any one of claims 1 to 8. The display panel includes multiple data signal lines and multiple gating signal lines. The intersection of the data signal lines and the gating signal lines forms a pixel. The cholesteric liquid crystal in the pixel has at least a planar state as a bright display state and a focal conic state as a dark display state. No thin-film transistors are disposed at the pixel of the display panel.

10. A driving method for a cholesteric liquid crystal passive matrix display panel, characterized in that, A driving device is applied to a cholesteric liquid crystal passive matrix display panel, comprising a data driving circuit, a gating driving circuit, and a timing control unit. The data driving circuit and the gating driving circuit are respectively connected to multiple data signal lines and multiple gating signal lines of the display panel, and the intersection of the data signal lines and the gating signal lines forms a pixel. The timing control unit is connected to the data driving circuit and the gating driving circuit and is used to drive the corresponding pixel through the potential difference between the data signal lines and the gating signal lines. The driving methods for cholesteric liquid crystal passive matrix display panels include: During the line-by-line refresh process: Determine the current scan line, and the row window that follows the current scan line and includes multiple rows to be refreshed; During the row refresh cycle of the current scan line, in the first precharge phase, a first pressure difference is applied to the pixels in the row window; the first pressure difference causes the cholesteric liquid crystal to enter or remain in a focal conic state, which is a dark display state; In the second pre-charge stage, according to the target image data, a second pressure difference is applied to the pixels in the current scan line where the target is in a bright state, and the pixels in the current scan line where the target is in a dark state are in the focal cone state, so as to complete the display writing of the current scan line; the second pressure difference causes the cholesteric liquid crystal to enter or remain in a planar state, and the planar state is a bright display state; The pressure difference between the pixels of the current scan line and other lines outside the line window is made less than the display state transition threshold, which is the minimum pressure difference required to change the display state of the cholesteric liquid crystal. The row window moves as the current scan row progresses, so that each row to be refreshed completes the first pre-charge phase before becoming the current scan row.

Images