Electronic paper and driving module thereof

Abstract

The invention discloses electronic paper and a driving module thereof, and the driving module comprises a total driving port which is used for outputting a periodic voltage sequence; the parallel branch group comprises n branches, one end of each branch is connected to the main driving port, and the other end of each branch is connected to the cholesteric liquid crystal layer of the electronic paper module through an alternating-current common-stage end wire; the adjusting resistor unit comprises m groups of adjusting resistors, one group of adjusting resistors is connected in series between any two branches in the n branches, n is greater than or equal to 4, and m is greater than or equal to 2; and the impedance balancing logic unit is used for configuring the resistance values of the m groups of adjusting resistors according to the routing resistance value of each branch, so that the total impedance of all branches is equal. According to the electronic paper driving module, the differential adjusting resistors are connected in series in different branches, uneven current distribution caused by wiring resistance difference is compensated, and the total impedance of all the branches is equal, so that charging and discharging currents are balanced, and the problem of device burnout caused by local overcurrent in a high-temperature environment is solved.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and in particular, to an electronic paper and its driving module. Background Art

[0002] Cholesteric liquid crystals are widely used in electronic paper display technologies due to their bistable characteristics. As Figures 1-3 shown, in the existing active driving scheme, a periodic voltage (+ common voltage → 0 → - common voltage → 0V) is applied to the liquid crystal layer through the AC common electrode traces on the color filter substrate side. However, in large-size modules, as the panel size increases, the uneven distribution of the resistance of the AC common electrode traces leads to significant differences in the charging and discharging currents. As Figure 4 shown, for a conventional AC common electrode design, the gradient distribution of the resistance of the AC common electrode traces, that is, the resistance is low on both sides and high in the middle, results in severely uneven charging and discharging currents. As Figure 5 and Figure 6 shown, the current of the edge traces is as high as 5A, while the current of the center traces is less than 1A. This current imbalance can cause the bonding pins to burn out due to local overcurrent. When the current of the middle branch is too low, it affects the liquid crystal response speed; the large-current area accelerates aging at high temperatures, resulting in screen failure. Summary of the Invention

[0003] To solve the technical problems existing in the background art, the present invention proposes an electronic paper driving module.

[0004] In a first aspect, an electronic paper driving module proposed by the present invention includes: A total driving port for outputting a periodic voltage sequence; A parallel branch group including n branches, one end of each branch is connected to the total driving port, and the other end is connected to the cholesteric liquid crystal layer of the electronic paper module through an AC common electrode trace; An adjustable resistance unit including m groups of adjustable resistors, and a group of adjustable resistors is connected in series between any two of the n branches, where n≥4 and m≥2; An impedance balancing logic unit for configuring the resistance values of the m groups of adjustable resistors according to the trace resistance values of each branch so that the total impedance of all branches is equal.

[0005] Preferably, a group of adjustable resistors is connected in series between any two of the n branches, specifically: The n branches are arranged in sequence from top to bottom with the position of the total driving port as a reference, and one branch is connected in series with a group of adjustable resistors one by one, where: The first branch and the nth branch are connected in series with a first adjustable resistor R1; The second branch and the (n - 1)th branch are connected in series with a second adjustable resistor R2; The third branch and the (n - 2)th branch are connected in series with a third adjustable resistor R3; By analogy, the k-th branch and the (n - k + 1)-th branch are connected in series with the k-th adjustable resistor Rk, where k = 1, 2, …, m.

[0006] Preferably, the resistance values of the m groups of adjustable resistors decrease from both sides to the middle according to the corresponding branch positions.

[0007] Preferably, when the n branches are specifically six branches, the first branch and the sixth branch are connected in series with the first adjustable resistor R1, the second branch and the fifth branch are connected in series with the second adjustable resistor R2; the third branch and the fourth branch are connected in series with the third adjustable resistor R3, where the resistance value relationship of the first adjustable resistor R1, the second adjustable resistor R2, and the third adjustable resistor R3 satisfies R1 > R2 > R3.

[0008] Preferably, the resistance value configuration of each group of adjustable resistors in the adjustable resistor unit satisfies: ; where is the total resistance value of any one of the n branches; is the trace resistance value of any one of the n branches; is the resistance value of the adjustable resistor corresponding to any one of the n branches.

[0009] Preferably, the impedance balancing logic unit includes: a data acquisition module for acquiring the trace resistance values of each branch among the n branches through simulation modeling or actual measurement; a compensation calculation module for calculating the corresponding compensation resistance value, that is, the resistance value of the adjustable resistor, according to the trace resistance value.

[0010] Preferably, the application timing of the periodic voltage sequence is: The first stage t1: Apply a positive common voltage for a duration of t1 to drive the liquid crystal molecules to switch to the H state; The second stage t2: Drop to 0V for a duration of t2 to stabilize the electric field distribution; The third stage t3: Apply a negative common voltage for a duration of t3 to drive the liquid crystal molecules to switch to the P state or the FC state; The fourth stage t4: Drop to 0V again for a duration of t4 to complete the charge and discharge cycle.

[0011] Preferably, it further includes: a dynamic feedback module for monitoring the current values of each branch in real time and adjusting the resistance value of the adjustable resistor according to the current deviation to keep the current stable within a preset range.

[0012] In a second aspect, an electronic paper proposed by the present invention includes the electronic paper driving module according to any one of the above.

[0013] In the present invention, an electronic paper driving module is proposed. The driving module includes a total driving port, a parallel branch group, an adjustable resistance unit, and an impedance equalization logic unit. By connecting different adjustable resistors in series in different branches, the uneven current distribution caused by the difference in trace resistance is compensated, so that the total impedance of all branches is equal, thereby balancing the charging and discharging current and avoiding the problem of device burnout caused by local overcurrent in a high-temperature environment. The present invention is applicable to large-size cholesteric liquid crystal electronic paper modules, significantly improving the reliability and service life of the products.

[0014] The present invention also proposes an electronic paper including the above-mentioned electronic paper driving module.

[0015] In the present invention, the technical effects of the proposed electronic paper are similar to those of the above driving module, so they will not be elaborated here. Description of the Drawings

[0016] Figure 1 Schematic diagram of a cholesteric liquid crystal electronic paper module; Figure 2 Schematic diagram of the substrate distribution of a cholesteric liquid crystal electronic paper module; Figure 3 Schematic diagram of the common electrode distribution of a cholesteric liquid crystal electronic paper module; Figure 4 Schematic diagram of the AC common electrode charging and discharging of a cholesteric liquid crystal electronic paper module; Figure 5 Schematic diagram of the driving structure of the prior art; Figure 6 Schematic diagram of current overcharge of the prior art; Figure 7 Schematic diagram of the driving structure of six branches of an electronic paper driving module proposed by the present invention; Figure 8 Schematic diagram of the equivalent circuit structure of the driving structure of six branches of an electronic paper driving module proposed by the present invention; Figure 9 Schematic diagram of the current distribution of six branches of an electronic paper driving module proposed by the present invention; Figure 10 Schematic diagram of the driving module of an electronic paper driving module proposed by the present invention. Detailed Embodiments

[0017] Referring to Figures 1-10 , an electronic paper driving module proposed by the present invention includes: A total driving port for outputting a periodic voltage sequence.

[0018] In this embodiment, the application timing of the periodic voltage sequence is as follows: The first stage t1: applying a positive common electrode voltage for a duration of t1 to drive the liquid crystal molecules to switch to the H state; The second stage t2: It drops to 0V, with a duration of t2, to stabilize the electric field distribution; The third stage t3: A negative common-level voltage is applied, with a duration of t3, to drive the liquid crystal molecules to switch to the P state or the FC state; The fourth stage t4: It drops to 0V again, with a duration of t4, to complete the charge-discharge cycle.

[0019] The parallel branch group includes n branches. One end of each branch is connected to the total drive port, and the other end accesses the cholesteric liquid crystal layer of the electronic paper module through the AC common-level terminal trace.

[0020] The regulating resistor unit includes m groups of regulating resistors. One group of regulating resistors is connected in series between any two branches among the n branches, where n≥4 and m≥2.

[0021] The impedance equalization logic unit is used to configure the resistance values of the m groups of regulating resistors according to the trace resistance values of each branch, so that the total impedance of all branches is equal.

[0022] To illustrate the electronic paper drive module of this embodiment in detail, this embodiment also proposes an electronic paper that uses different states of cholesteric liquid crystal to achieve the display function.

[0023] It should be noted that cholesteric liquid crystal (Cholesteric Liquid Crystal) will present multiple states under different conditions. The common ones include the H state, the P state, and the FC state. The following is the detailed description of these states: 1. H state (Homeotropic State, perpendicular alignment state) Characteristics: The liquid crystal molecules are arranged perpendicular to the substrate surface, the helical structure is destroyed, and the helical axis of the cholesteric phase disappears.

[0024] Forming conditions: Usually formed under the action of a strong electric field or surface treatment (such as a vertical alignment layer).

[0025] Optical characteristics: It shows a transparent state because the molecular arrangement is uniform, and light will not be scattered or selectively reflected when passing through.

[0026] Applications: Used in electro-optical devices, such as fast-switching transparent / scattering state displays.

[0027] 2. P state (Planar State, planar state) Characteristics: The liquid crystal molecules are arranged in the plane parallel to the substrate, the helical axis is perpendicular to the substrate surface, and the helical structure is complete.

[0028] Forming conditions: The state naturally presented by cholesteric liquid crystal under no external electric field or weak electric field.

[0029] Optical properties: Exhibits selective reflection, and the wavelength of the reflected light is determined by the pitch, usually presenting bright colors.

[0030] Applications: Used in reflective displays, optical filters, and color display devices.

[0031] The electronic paper of this embodiment adopts an active cholesteric LCD single-pixel driving architecture, mainly composed of a gate line, a source line, a thin-film transistor on the thin-film transistor substrate side, a common line on the color filter substrate side, and a pixel unit. By applying a voltage between the common electrode of the color filter substrate and the pixel electrode of the thin-film transistor substrate, the state of the pixel unit is controlled. Among them, the source line is used to send data to the drain of the thin-film transistor, the gate line controls the gate of the thin-film transistor to control the on or off of the thin-film transistor, and the pixel unit is connected to the source of the thin-film transistor, used to receive and store data signals and form an electric field with the common electrode to control the deflection of the liquid crystal.

[0032] The existing active driving scheme applies a periodic voltage (+ common voltage → 0 → - common voltage → 0V) to the liquid crystal cells of the liquid crystal layer through the AC common-level trace on the color filter substrate side. However, in large-size modules, the gradient distribution of the resistance of the AC common-level trace, that is, the resistance is low on both sides and high in the middle, leads to serious uneven charge and discharge currents. When the current in the two side branches is too high, it is easy to cause the bonding pins to burn out. When the current in the middle branch is too low, it affects the liquid crystal response speed; the large-current area accelerates aging at high temperatures, resulting in screen failure.

[0033] Therefore, in this embodiment, by connecting differential adjustment resistors in series in different branches, the uneven current distribution caused by the difference in trace resistance is compensated, so that the total impedance of all branches is equal, thereby balancing the charge and discharge currents and avoiding the problem of device burnout caused by local overcurrent in a high-temperature environment.

[0034] In the specific implementation manner of this embodiment, the impedance equalization logic unit includes: A data acquisition module, used to obtain the trace resistance values of each branch in n branches through simulation modeling or actual measurement; A compensation calculation module, which calculates the corresponding compensation resistance value, that is, the resistance value of the adjustment resistor, according to the trace resistance value.

[0035] In this embodiment, a set of adjustment resistors is connected in series between any two of the n branches, specifically: The n branches are arranged in sequence from top to bottom with the position of the total driving port as the reference, and one branch is connected in series with a set of adjustment resistors one by one, where: The first branch and the nth branch are connected in series with the first adjustment resistor R1; The second branch and the (n - 1)th branch are connected in series with the second adjustment resistor R2; The third branch and the (n - 2)th branch are connected in series with the third adjustment resistor R3; By analogy, the k-th branch is connected in series with the (n - k + 1)-th branch and the k-th adjustable resistor Rk, where k = 1, 2, …, m.

[0036] In this embodiment, the resistance values of the m groups of adjustable resistors decrease from both sides to the middle according to the corresponding branch positions.

[0037] Specifically, the adjustable resistor unit includes m adjustable resistors with different resistance values (R1, R2,..., Rm, and R1 > R2 >... > Rm). The resistance values are allocated according to the symmetric positions of the branches. Specifically: the two branches farthest from the total drive port are connected in series with the largest resistance R1; if the number of branches n ≥ 4, the two branches at the second farthest sides are connected in series with the second largest resistance R2; by analogy, the middle branches (existing when n ≥ 2m + 1) are connected in series with the smallest resistance Rm; through the above resistance value gradient configuration, the total impedance of all branches is made equal.

[0038] In a specific embodiment, as Figures 7-9 shown, when the n branches are specifically six branches, the first branch is connected in series with the sixth branch and the first adjustable resistor R1, the second branch is connected in series with the fifth branch and the second adjustable resistor R2; the third branch is connected in series with the fourth branch and the third adjustable resistor R3, where the resistance value relationship of the first adjustable resistor R1, the second adjustable resistor R2, and the third adjustable resistor R3 satisfies R1 > R2 > R3.

[0039] Specifically, adjustable resistors are connected in series at the positions where the six branches P1~P6 are connected to the total AC common port, and the impedances of the 12 parallel signal lines corresponding to the six branches are adjusted to be the same. Among them, P1 / P6 are connected in series with the large resistance R1, P2 / 5 are connected in series with the medium resistance R2, P3 / 4 are connected in series with the small resistance R3. After adjustment, the current of each path can be limited within 2.6A, and at the same time, the total discharge current is ensured to be close. Connecting resistors will cause a certain degree of current drop, which does not affect the normal charge and discharge speed. After adjustment, since the current output of all paths is basically the same, the port is not easily burned out.

[0040] Taking Figure 7 the shown driving structure as an equivalent Figure 8 model, that is, the AC common level charges and discharges the six branches P1~P6 from both left and right sides. Since the pair of charge and discharge paths of the six branches P1~P6 are close in distance, the 0.5Ω resistor in the middle can be ignored, and the two paths of each branch are equivalent to parallel resistors. The equivalent parallel equivalent resistance of each group of the six branches P1~P6 is 2.8Ω. The middle series resistors are as Figure 8 shown respectively: 2.3Ω, 32.2Ω, 100Ω, 32.1Ω, 2.4Ω; calculated according to the AC common level of 30V, the initial currents flowing through P1~P6 are calculated as: 10.89A, 6.06A, 1.02A, 1.01A, 5.95A, 10.89A.

[0041] For the six branches P1 - P6, the regulating resistors are in series. In this embodiment, since the current in branches P3 - P4 is already below 2.6A, no additional resistors are needed. The corresponding resistors for the six branches P1 - P6 are: 6Ω, 4Ω, 2.8Ω, 2.8Ω, 4Ω, 6Ω. After calculation, the single - path currents of the six branches P1 - P6 become: 5.18A, 4.94A, 1.02A, 0.95A, 4.86A, 5.17A. Each branch in the six branches P1 - P6 has 2 discharge paths, so the single - path discharge currents in the six branches P1 - P6 become: 2.59A, 2.47A, 0.51A, 0.48A, 2.43A, 2.59A; the final output is as Figure 9 shown.

[0042] Specifically, as Figure 8 shown, the resistance value configuration of each group of regulating resistors in the regulating resistor unit satisfies: ; where, is the total resistance value of any one of the n branches; is the trace resistance value of any one of the n branches; is the resistance value of the regulating resistor corresponding to any one of the n branches.

[0043] In this embodiment, it further includes: A dynamic feedback module, which is used to monitor the current values of each branch in real - time and adjust the resistance value of the regulating resistor according to the current deviation to keep the current stable within a preset range.

[0044] An electronic paper proposed by the present invention includes an electronic paper driving module according to any one of the above.

[0045] This embodiment is particularly applicable to large - size cholesteric liquid crystal electronic paper modules, significantly improving the reliability and service life of the product.

[0046] The above - mentioned is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. An electronic paper driving module, characterized in that, Comprising: A total drive port for outputting a periodic voltage sequence; A parallel branch group including n branches, one end of each branch being connected to the total drive port and the other end accessing the cholesteric liquid crystal layer of the electronic paper module through an AC common terminal trace; An adjustment resistance unit including m groups of adjustment resistors, with a group of adjustment resistors connected in series between any two of the n branches, where n≥4 and m≥2; An impedance equalization logic unit for configuring the resistance values of the m groups of adjustment resistors according to the trace resistance values of each branch so that the total impedance of all branches is equal.

2. The electronic paper driving module according to claim 1, wherein A group of adjustment resistors is connected in series between any two of the n branches, specifically: The n branches are arranged in sequence from top to bottom with the position of the total drive port as the reference, and one branch is connected in series with a group of adjustment resistors one by one, where: The first branch and the nth branch are connected in series with a first adjustment resistor R1; The second branch and the (n - 1)th branch are connected in series with a second adjustment resistor R2; The third branch and the (n - 2)th branch are connected in series with a third adjustment resistor R3; And so on, the kth branch and the (n - k + 1)th branch are connected in series with the kth adjustment resistor Rk, where k = 1, 2, …, m.

3. The electronic paper driving module according to claim 2, wherein The resistance values corresponding to the m groups of adjustment resistors decrease from both sides to the middle according to the corresponding branch positions.

4. The electronic paper driving module according to claim 3, characterized in that, When the n branches are specifically six branches, the first branch and the sixth branch are connected in series with a first adjustment resistor R1, the second branch and the fifth branch are connected in series with a second adjustment resistor R2; the third branch and the fourth branch are connected in series with a third adjustment resistor R3, where the resistance value relationship of the first adjustment resistor R1, the second adjustment resistor R2, and the third adjustment resistor R3 satisfies R1 > R2 > R3.

5. The electronic paper driving module according to claim 3, characterized in that The resistance values of the adjustable resistors in each group of the adjustable resistor unit satisfy: ; Among them, is the total resistance value of any one of the n branches; is the trace resistance value of any one of the n branches; is the resistance value of the adjustment resistor corresponding to any one of the n branches.

6. The electronic paper driving module according to claim 5, wherein The impedance equalization logic unit includes: A data acquisition module for acquiring the trace resistance values of each branch among the n branches through simulation modeling or actual measurement; A compensation calculation module for calculating the corresponding compensation resistance value, i.e., the resistance value of the adjustment resistor, according to the trace resistance value.

7. The electronic paper driving module according to claim 1, wherein The application timing of the periodic voltage sequence is as follows: The first stage t1: Applying a positive common voltage for a duration of t1 to drive the liquid crystal molecules to switch to the H state; The second stage t2: Dropping to 0V for a duration of t2 to stabilize the electric field distribution; The third stage t3: Applying a negative common voltage for a duration of t3 to drive the liquid crystal molecules to switch to the P state or the FC state; The fourth stage t4: Dropping to 0V again for a duration of t4 to complete the charge and discharge cycle.

8. The electronic paper driving module according to claim 1, wherein, It further includes: A dynamic feedback module for monitoring the current values of each branch in real time and adjusting the resistance value of the adjustment resistor according to the current deviation to keep the current stable within a preset range.

9. An electronic paper, characterized in that, Including the electronic paper drive module according to any one of claims 1 - 8.

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