Liquid crystal handwriting board and handwriting device

Abstract

The application relates to a liquid crystal handwriting board and a handwriting device. The liquid crystal handwriting board comprises a liquid crystal panel and a driving assembly electrically connected with the liquid crystal panel. The liquid crystal panel comprises a first substrate and a second substrate arranged oppositely, and a liquid crystal layer between the first substrate and the second substrate. The first substrate comprises a plurality of block-shaped pixel electrodes, a plurality of photoelectric layers and a plurality of thin film transistors. The thin film transistor is configured to be turned on after being irradiated. The photoelectric layer is configured to generate photo-generated carriers after being irradiated. The pixel electrode is electrically connected with at least one thin film transistor, and at least one photoelectric layer is electrically connected. The thin film transistor is electrically connected with the driving assembly, and the photoelectric layer is electrically connected with the driving assembly. The second substrate comprises a planar common electrode. The photoelectric layer is further configured to charge the pixel electrode after being irradiated. The driving assembly is configured to apply a pixel voltage to the pixel electrode when the liquid crystal handwriting board is in an erasing mode.

Description

Technical Field

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

[0002] Among related technologies, compared to traditional handwriting tablets and display interaction designs, LCD handwriting tablets offer advantages such as low power consumption, eye-friendliness, and ease of operation, making them a popular design trend in the market. Active erasable handwriting tablets offer a significantly improved user experience compared to traditional passive ones and represent the mainstream design approach for the future.

[0003] LCD handwriting tablets can be partially erased by illuminating the tablet with an active light-emitting erasing device, thus eliminating the need for the complex module design commonly used for infrared positioning. However, the above solution has the problem of difficulty in achieving high sensitivity and high discrimination of optical erasing. Summary of the Invention

[0004] This application provides a liquid crystal handwriting tablet and a handwriting device to address all or part of the shortcomings in the related technologies.

[0005] According to a first aspect of the embodiments of this application, a liquid crystal handwriting tablet is provided, the liquid crystal handwriting tablet including a liquid crystal panel and a driving component electrically connected to the liquid crystal panel;

[0006] The liquid crystal panel includes a first substrate and a second substrate disposed opposite to each other, and a liquid crystal layer located between the first substrate and the second substrate; the first substrate includes a plurality of block-shaped pixel electrodes, a plurality of photoelectric layers, and a plurality of thin-film transistors; the thin-film transistors are configured to conduct after being illuminated; the photoelectric layers are configured to generate photogenerated carriers after being illuminated; the pixel electrodes are electrically connected to at least one of the thin-film transistors, and the pixel electrodes are also electrically connected to at least one of the photoelectric layers; the thin-film transistors are electrically connected to the driving component, and the photoelectric layers are electrically connected to the driving component; the second substrate includes a planar common electrode; the photoelectric layer is further configured to charge the pixel electrodes after being illuminated.

[0007] The driving component is configured to apply a pixel voltage to the pixel electrode when the liquid crystal writing tablet is in erase mode.

[0008] In some embodiments, the photoelectric layer is located on the side of the pixel electrode away from the second substrate; a gate insulating layer is provided between the photoelectric layer and the pixel electrode, and the pixel electrode is electrically connected to the pixel electrode through a via.

[0009] In some embodiments, the liquid crystal writing tablet further includes a gate insulating layer, a conductive portion, a first trace, and a second trace; a plurality of first traces extend along a first direction, and a plurality of second traces extend along a second direction; the first direction and the second direction intersect; the thin film transistor is electrically connected to the driving component through the first trace and the second trace; the conductive portion is located between the photoelectric layer and the via;

[0010] The pixel electrode is electrically connected to the conductive portion through a via, and is electrically connected to the photoelectric layer through the conductive portion; one end of the photoelectric layer is electrically connected to the second trace, and the other end of the photoelectric layer away from the second trace is electrically connected to the conductive portion; the gate insulating layer is located between the photoelectric layer and the pixel electrode, and between the second trace and the conductive portion.

[0011] In some embodiments, the liquid crystal writing tablet includes metal traces, a plurality of first traces extending along a first direction, and a plurality of second traces extending along a second direction; the first traces and the second traces intersect; the thin-film transistor is electrically connected to the driving component through the first traces and the second traces;

[0012] The photoelectric layer is located on the side of the pixel electrode away from the second substrate; the metal trace is located on the side of the photoelectric layer away from the pixel electrode and is electrically connected to the second trace; the photoelectric layer is electrically connected to the driving component through the metal trace.

[0013] In some embodiments, the photoelectric layer includes sequentially stacked P-type doped regions, I-type doped regions, and N-type doped regions, wherein the P-type doped regions are doped with trivalent elements and the N-type doped regions are doped with pentavalent elements; the N-type doped regions are electrically connected to the pixel electrode, the P-type doped regions are electrically connected to the driving component, and the I-type doped regions are configured to generate photogenerated carriers when illuminated.

[0014] In some embodiments, the projection of the photoelectric layer onto the second substrate lies within the projection of the pixel electrode onto the second substrate.

[0015] In some embodiments, the material of the metal trace includes indium tin oxide glass.

[0016] In some embodiments, the material of the photoelectric layer includes amorphous silicon.

[0017] In some embodiments, the ratio of the area of ​​the photoelectric layer to the area of ​​the pixel electrode electrically connected to the photoelectric layer is greater than or equal to 0.3 and less than or equal to 0.9.

[0018] In some embodiments, the second substrate is a flexible substrate.

[0019] In some embodiments, the liquid crystal layer contains bistable liquid crystal molecules.

[0020] According to a second aspect of the embodiments of this application, a handwriting device is also provided, the handwriting device including any of the above-described liquid crystal handwriting tablets.

[0021] As can be seen from the above embodiments, since the photoelectric layer can generate photogenerated carriers after being illuminated, and the photoelectric layer is configured to charge the pixel electrode after being illuminated, the problem of the small photosensitive area of ​​the thin-film photoelectric layer can be effectively improved, thereby increasing the light utilization rate of the liquid crystal writing tablet. Due to the improved light utilization rate, it is possible to increase the difference in charging rate between the light source position and the natural background light position of the erasing device while using a smaller gate voltage, thus achieving higher light erasing sensitivity and separation. Simultaneously, the structure of this liquid crystal writing tablet can improve the light erasing performance without adding a new driving device, thereby avoiding structural complexity.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0024] Figure 1 The diagram shown is a schematic of the structure of a liquid crystal handwriting tablet;

[0025] Figure 2 The diagram shown is a partial schematic of a liquid crystal handwriting tablet;

[0026] Figure 3 The diagram shown illustrates the principle of how an LCD handwriting tablet displays handwriting.

[0027] Figure 4 This is a partial schematic diagram of a liquid crystal handwriting tablet according to an embodiment of this application;

[0028] Figure 5 As shown in the embodiments of this application Figure 4 Cross-sectional view at section line AA;

[0029] Figure 6 As shown in the embodiments of this application Figure 4 Cross-sectional view at the mid-section line BB;

[0030] Figure 7 It is a graph showing the voltage changes at the pixel electrode according to an embodiment of this application;

[0031] Figure 8 This is a partial schematic diagram of another liquid crystal handwriting tablet according to an embodiment of this application;

[0032] Figure 9 As shown in the embodiments of this application Figure 8 Cross-sectional view at the mid-section line CC. Detailed Implementation

[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0034] The following is a brief introduction to LCD writing tablets that use an active-matrix erasing device for erasing. Figure 1 The diagram shown is a structural schematic of an LCD handwriting tablet, such as... Figure 1 As shown, the LCD handwriting tablet includes: an LCD panel 10, a driving component 20, and a black substrate 30. The driving component 20 is located between the LCD panel 10 and the black substrate 30, and the LCD panel 10 and the driving component 20 are electrically connected.

[0035] The liquid crystal panel 10 includes a first substrate 11, a second substrate 12, and a liquid crystal layer 13. The first substrate 11 and the second substrate 12 are disposed opposite to each other, and the liquid crystal layer 13 is located between the first substrate 11 and the second substrate 12. The liquid crystal layer 13 is filled with liquid crystal molecules 131. Figure 2 What is shown is Figure 1 A partial schematic diagram of the LCD handwriting tablet in the image; specifically, it is... Figure 1 A partial schematic diagram of the first substrate 11 of the liquid crystal handwriting panel, for reference. Figure 2 As shown, the first substrate 11 includes: a pixel electrode 111, a thin-film transistor 112, a first trace 113, and a second trace 114. The first trace 113 extends along a first direction X, and the second trace 114 extends along a second direction Y. The first direction X and the second direction Y are perpendicular to each other. The block-shaped pixel electrode 111 is electrically connected to the thin-film transistor 112, and the thin-film transistor 112 is electrically connected to the driving assembly 20 through the first trace 113 and the second trace 114. It should be noted that... Figure 2For clarity, only one pixel electrode 111 is shown, but in reality, the first substrate 11 includes multiple block-shaped pixel electrodes 111 arranged in an array. A thin-film transistor 112 contains a thin-film photoelectric layer 1121, which is configured to generate photogenerated carriers upon illumination. The second substrate 12 has a planar common electrode (not shown). The liquid crystal molecules 131 in the liquid crystal layer 13 include bistable liquid crystals. The driving assembly 20 is located on the side of the first substrate 11 away from the second substrate 12. The black substrate 30 is located on the side of the driving assembly 14 away from the first substrate 11, and the black substrate 30 can be a black aluminum honeycomb panel.

[0036] Bistable liquid crystal molecules possess planar texture (P-state), focal conic texture (FC-state), and hometropic texture (H-state). Among these, the P-state and FC-state are stable states that can be maintained without voltage, while the H-state is an unstable state that is exhibited when a voltage is continuously applied. Figure 3 The diagram shown illustrates the principle of how an LCD handwriting tablet displays handwriting. Figure 3 As shown, when the LCD handwriting tablet is in writing mode, the writing tool S1 can apply pressure to the LCD handwriting tablet, causing some liquid crystal molecules in the liquid crystal layer 13 of the LCD handwriting tablet to change from a focal conical texture to a planar texture under the action of external pressure. In this way, the liquid crystal molecules that have changed to a planar texture can reflect light of a certain wavelength in the incident ambient light, so that the LCD handwriting tablet can display handwriting. The writing tool S1 can be a writing pen, but is not limited to it.

[0037] Meanwhile, the liquid crystal molecules in the area not subjected to pressure by the writing tool S1 have a focal conic texture. The focal conic textured liquid crystal molecules can transmit incident ambient light, allowing the area not subjected to pressure by the writing tool S1 to display a black background with the same color as the black substrate 30.

[0038] When the LCD writing pad is in erase mode, the eraser (not shown in the figure) moves on the LCD writing pad. It should be noted that although the eraser is not shown in the figure, its relative position to the LCD panel 10 can be referenced to the relative position of the writing instrument S1 and the LCD panel 10. After receiving light from the eraser, the thin-film photoelectric layer 1121 generates photogenerated carriers. These photogenerated carriers form a channel within the thin-film transistor 112, thus turning on the thin-film transistor 112. The area where the thin-film transistor 112 is turned on is the area to be erased. Simultaneously, the driving component 20 can apply a source voltage to the thin-film transistor 112 located in the area to be erased to charge the pixel electrode 111 located in the area to be erased. This creates a voltage difference between the pixel electrode 111 and the common electrode in the area to be erased, causing the liquid crystal molecules 131 in the area to be erased to rearrange under the influence of this voltage difference. That is, the liquid crystal molecules 131 can change from a planar texture to a focal cone texture. In this way, the liquid crystal molecules 131, transformed into a focal cone texture, do not reflect the incident ambient light, allowing the area to be erased to display a black background identical in color to the black substrate 30, thereby erasing the writing within the area to be erased. Simultaneously, since the thin-film transistors 112 located outside the area to be erased are not illuminated, they do not conduct, thus preventing the pixel electrodes outside the area from charging and maintaining the writing within that area. This enables partial erasure of the liquid crystal writing tablet.

[0039] In the above scheme, the ratio of the area of ​​the thin film photoelectric layer 1121 to the area of ​​the pixel electrode 111 electrically connected to the thin film photoelectric layer 1121 is less than 0.05, which results in poor light utilization of the thin film photoelectric layer 1121 and makes it impossible to achieve a high-sensitivity and high-resolution light erasure effect.

[0040] To address the aforementioned problems, embodiments of this application provide a liquid crystal handwriting tablet, wherein the structure of the liquid crystal handwriting tablet is similar to... Figure 1 The structure of the LCD handwriting tablet shown is similar, and the principle by which the LCD handwriting tablet displays handwriting can be found by referring to... Figure 3 The diagram illustrates the principle behind how the LCD handwriting tablet displays handwritten notes. Figure 4 This is a partial schematic diagram of a liquid crystal writing tablet according to an embodiment of this application. Specifically, it is a partial schematic diagram of the first substrate 11 of the liquid crystal writing tablet, as shown below. Figure 4 As shown, and with reference Figure 1 As shown, the first substrate 11 includes: a pixel electrode 111, a thin film transistor 112, a first trace 113, and a second trace 114.

[0041] The first trace 113 extends along the first direction X, and the second trace 114 extends along the second direction Y. Specifically, the first direction X and the second direction Y intersect, and are perpendicular to each other. The block-shaped pixel electrode 111 is electrically connected to the thin-film transistor 112, and the thin-film transistor 112 is electrically connected to the driving assembly 20 via the first trace 113 and the second trace 114. It should be noted that... Figure 4 For clarity, only one pixel electrode 111 is shown, but in reality, the first substrate 11 includes multiple block-shaped pixel electrodes 111 arranged in an array. A thin-film transistor 112 contains a thin-film photoelectric layer 1121, which is configured to generate photogenerated carriers upon illumination. The second substrate 12 has a planar common electrode (not shown). The liquid crystal molecules 131 in the liquid crystal layer 13 include bistable liquid crystals. The driving assembly 20 is located on the side of the first substrate 11 away from the second substrate 12. The black substrate 30 is located on the side of the driving assembly 14 away from the first substrate 11, and the black substrate 30 can be a black aluminum honeycomb panel.

[0042] Figure 5 What is shown is Figure 4 The cross-sectional view at section line AA is shown below. Figure 4 and Figure 5 As shown, the thin-film transistor 112 includes: a thin-film photoelectric layer 1121, a first electrode 1122, a second electrode 1123, a first gate insulating layer 1124, a first insulating layer 1125, a second insulating layer 1126, a gate 1127, and a glass substrate 1128. The gate 1127 is located on the glass substrate 1128. The first insulating layer 1125 is located on the side of the gate 1127 away from the glass substrate 1128. The first gate insulating layer 1124 is located on the side of the first insulating layer 1125 away from the gate 1127. The thin-film photoelectric layer 1121 is located on the side of the first gate insulating layer 1124 away from the first insulating layer 1125. The second insulating layer 1126 is located on the side of the thin-film photoelectric layer 1121 away from the first gate insulating layer 1124. The first electrode 1122 and the second electrode 1123 are located between the second insulating layer 1126 and the thin-film photoelectric layer 1121.

[0043] In this design, the first electrode 1122 can be either the source or the drain, and the second electrode 1123 can be either the source or the drain. The first electrode 1122 can be a U-shaped structure, and the second electrode 1123 can be a strip-shaped structure. One end of the second electrode 1123 is located within the U-shaped structure of the first electrode 1122, and the other end is electrically connected to the pixel electrode 111. The end of the first electrode 1122 furthest from the second electrode 1123 is electrically connected to the second trace 114.

[0044] Furthermore, the first pole 1122 has a first extension 1122a, a second extension 1122b, and a third extension 1122c connected in sequence. The first extension 1122a and the third extension 1122c can extend in the same direction, the second extension 1122b can extend in a direction perpendicular to the first extension 1122a, and the second extension 1122b can extend in a direction perpendicular to the third extension 1122c. This configuration, with the first extension 1122a, the second extension 1122b, and the third extension 1122c connected in sequence, forms a U-shaped structure for the first pole 1122.

[0045] Since the channel between the first electrode 1122 and the second electrode 1123 in the thin-film transistor 112 is a U-shaped channel, the U-shaped channel region can have a large aspect ratio, thereby enabling the thin-film transistor 112 to withstand a higher breakdown voltage, and thus improving the service life of the liquid crystal handwriting tablet.

[0046] The thin-film photoelectric layer 1121 generates photogenerated carriers after being illuminated by the erasing device. The driving component 20 sends a gate voltage to the gate 1127 via the first trace 113. Upon receiving the gate voltage, the gate 1127 generates an electric field, causing the photogenerated carriers in the thin-film photoelectric layer 1121 to form a channel. Subsequently, the pixel voltage emitted by the driving component 20 via the second trace 114 can pass through the channel formed by the photogenerated carriers from the first electrode 1122, and then through the second electrode 1123 before being received by the pixel electrode 111. This configuration enables the thin-film transistor 112 to conduct after being illuminated. Simultaneously, this configuration also creates a voltage difference between the pixel electrode 111 and the common electrode in the area to be erased, thereby causing the liquid crystal molecules 131 in the area to be erased to rearrange under the influence of this voltage difference, i.e., the liquid crystal molecules 131 can change from a planar texture to a focal conical texture. In this way, the liquid crystal molecules 131 that have transformed into a focal cone texture can transmit ambient light, so that the area to be erased can present a black background with the same color as the black substrate 30, thereby achieving the erasure of the writing marks in the area to be erased.

[0047] Figure 6 What is shown is Figure 4 The cross-sectional view at section line BB is shown below. Figure 4 and Figure 6As shown, the liquid crystal panel 10 further includes a photoelectric layer 115 and a via 117. A first insulating layer 1125 is located on a glass substrate 1128, a second gate insulating layer 118 is located on the side of the first insulating layer 1125 away from the glass substrate 1128, the photoelectric layer 115 is located on the side of the second gate insulating layer 118 away from the first insulating layer 1125, and a second insulating layer 1126 is located on the side of the photoelectric layer 115 away from the second gate insulating layer 118. A second trace 114 and another second gate insulating layer 118 are located between the second insulating layer 1126 and the photoelectric layer 115.

[0048] The photoelectric layer 115 is also configured to generate photogenerated carriers upon illumination. The pixel electrode 111 is electrically connected to at least one photoelectric layer 115. Specifically, the pixel electrode 111 may be electrically connected to one photoelectric layer 115, or two photoelectric layers 115, or three photoelectric layers 115, but is not limited thereto. In this embodiment, the pixel electrode 111 is electrically connected to one photoelectric layer 115. The photoelectric layer 115 is electrically connected to the driving assembly 20. Specifically, one end of the photoelectric layer 115 is electrically connected to the second trace 114, and the other end of the photoelectric layer 115 away from the second trace 114 is electrically connected to the pixel electrode 111 through a via 117.

[0049] In the above scheme, after the liquid crystal writing pad is illuminated by light emitted from the erasing device, the thin-film transistor 112 is turned on due to the light, and at the same time, the photoelectric layer 115 generates a large number of photogenerated carriers due to the light. At this time, a top-gate-like structure is formed in the liquid crystal panel 10, wherein the gate of the top-gate-like structure is the pixel electrode 111, the drain of the top-gate-like structure can be the second trace 114, the source of the top-gate-like structure can be the pixel electrode 111 located in the via 117, and the gate insulating layer of the top-gate-like structure is the second gate insulating layer 118. Subsequently, the pixel voltage emitted by the driving component 20 is received by the pixel electrode 111. When the voltage at the pixel electrode 111 reaches a first predetermined voltage, a channel is generated in the photoelectric layer 115 that electrically connects the second trace 114 and the pixel electrode 111. After a channel is generated within the photoelectric layer 115, the photocurrent generated by a large number of photogenerated carriers creates a voltage difference between the pixel electrode 111 and the common electrode. Consequently, the liquid crystal molecules 131 in the area to be erased rearrange under the influence of this voltage difference, that is, the liquid crystal molecules 131 can change from a planar texture to a focal conical texture. In this way, the liquid crystal molecules 131 that have changed to a focal conical texture can transmit incident ambient light, so that the area to be erased can present a black background with the same color as the black substrate 30, thereby realizing the erasure of the writing in the area to be erased.

[0050] Meanwhile, the voltage change at pixel electrode 111 during the above process can be referenced Figure 7The content shown is as follows: Figure 7 As shown in the graph, the vertical axis represents the voltage Vp at pixel electrode 111, and the horizontal axis represents time t. During time period T1, thin-film transistor 112 is turned on due to illumination, and simultaneously, photoelectric layer 115 generates a large number of photogenerated carriers due to illumination. During time period T2, the top-gate-like structure reaches the turn-on voltage, and the photocurrent generated by photoelectric layer 115 accelerates the charging of pixel electrode 111, reaching the erase voltage.

[0051] According to the above embodiments, since the photoelectric layer can generate photogenerated carriers after being illuminated, and the photoelectric layer is configured to charge the pixel electrode after being illuminated, the problem of the small photosensitive area of ​​the thin-film photoelectric layer 1121 can be effectively improved, thereby increasing the light utilization rate of the liquid crystal handwriting tablet. Due to the improved light utilization rate, a smaller gate turn-on voltage can be used while increasing the difference in charging rate between the light source position of the erasing device and the natural background light, thus achieving higher light erasing sensitivity and separation. Simultaneously, the structure of this liquid crystal handwriting tablet can improve light erasing performance without adding a new driving device, thereby avoiding structural complexity.

[0052] In some embodiments, the liquid crystal writing tablet further includes a conductive portion 116. The conductive portion 116 is located between the photoelectric layer 115 and the via 117. Specifically, the conductive portion 116 can be a strip-shaped conductive portion, and its extending direction can be parallel to the second direction Y. The material of the conductive portion 116 can include one or more of aluminum, copper, and molybdenum.

[0053] Pixel electrode 111 is electrically connected to conductive portion 116 through via 117, and to photoelectric layer 115 through conductive portion 116. One end of photoelectric layer 115 is electrically connected to second trace 114, and the other end of photoelectric layer 115 away from second trace 114 is electrically connected to conductive portion 116. Second gate insulating layer 118 is located between photoelectric layer 115 and pixel electrode 111. Specifically, second gate insulating layer 118 is located between second insulating layer 1126 and photoelectric layer 115. Furthermore, second gate insulating layer 118 is also located between second trace 114 and conductive portion 116, and second gate insulating layer 118 is in contact with photoelectric layer 115. The density of second gate insulating layer 118 is greater than that of second insulating layer 1126. Both second gate insulating layer 118 and second insulating layer 1126 can be formed by deposition process; however, the deposition rate of second gate insulating layer 118 is slower than that of second insulating layer 1126.

[0054] A denser second gate insulating layer 118 can be obtained by using a slower deposition process, thereby ensuring fewer defects in the second gate insulating layer 118 and ensuring that the second gate insulating layer 118 can effectively insulate the pixel electrode 111 from the photoelectric layer 115. Furthermore, the conductive portion 116 can serve as the source of a top-gate-like structure within the liquid crystal panel 10, further enhancing the transmission effect of the photocurrent generated by the photoelectric layer 115 within the top-gate-like structure.

[0055] In some embodiments, the ratio of the area of ​​the photoelectric layer 115 to the area of ​​the pixel electrode 111 electrically connected to the photoelectric layer 115 is greater than or equal to 0.3 and less than or equal to 0.9. This setting can prevent the area of ​​the photoelectric layer 115 from being too large and affecting the wiring around the photoelectric layer 115, or prevent the area of ​​the photoelectric layer 115 from being too small and unable to effectively charge the pixel electrode 111.

[0056] In some embodiments, the second substrate 12 may be a flexible substrate, and specifically, the material of the second substrate 12 may include polyimide (PI).

[0057] In some embodiments, the liquid crystal layer 13 comprises bistable liquid crystal. Specifically, the liquid crystal layer 13 may be entirely composed of bistable liquid crystal, or it may be partially composed of bistable liquid crystal.

[0058] This application embodiment also provides another liquid crystal handwriting tablet, wherein the structure of the liquid crystal handwriting tablet is similar to... Figure 1 The structure of the LCD handwriting tablet shown is similar, and the principle by which the LCD handwriting tablet displays handwriting can be found by referring to... Figure 3 The diagram illustrates the principle behind how the LCD handwriting tablet displays handwritten notes. Figure 8 This is a partial schematic diagram of another first substrate 11 according to an embodiment of this application, as shown below. Figure 8 As shown, and with reference Figure 1 The first substrate 11 shown includes: a pixel electrode 111, a thin-film transistor 112, a first trace 113, and a second trace 114. The structure and related description of the thin-film transistor 112, the first trace 113, and the second trace 114 can be found in the foregoing embodiments, and will not be repeated here.

[0059] Figure 9 What is shown is Figure 8 Cross-sectional view at the mid-section line CC, as shown Figure 8 and Figure 9As shown, the liquid crystal panel 10 further includes a photoelectric layer 115 and metal traces 119. A first insulating layer 1125 is located on a glass substrate 1128. The metal traces 119 are located on the side of the first insulating layer 1125 away from the glass substrate 1128. A second insulating layer 1126 and the photoelectric layer 115 are located on the side of the metal traces 119 away from the first insulating layer 1125, and the second insulating layer 1126 is adjacent to the photoelectric layer 115. A second trace 114 is located between the second insulating layer 1126 and the metal traces 119. A pixel electrode 111 is located on the side of the photoelectric layer 115 away from the metal traces 119.

[0060] Furthermore, the photoelectric layer 115 is also configured to generate photogenerated carriers upon exposure to light. The photoelectric layer 115 is also electrically connected to the second trace 114 via a metal trace 119. The metal trace 119 is made of indium tin oxide glass (ITO).

[0061] In the above scheme, after the liquid crystal writing tablet is exposed to light emitted by the erasing device, a large number of photogenerated carriers, i.e., electron-hole pairs, are formed in the photoelectric layer 115. Subsequently, when the second trace 114 emits an erasing voltage, the metal trace 119 overlaps with the second trace 114 to form a positive electrode, creating a voltage difference between the metal trace 119 and the pixel electrode 111. Due to the electric field generated by this voltage difference, free electrons move towards the positive electrode, and free holes move towards the negative electrode; that is, electrons move towards the metal trace 119, and holes move towards the pixel electrode 111. This generates a voltage difference between the pixel electrode 111 and the common electrode, causing the liquid crystal molecules 131 in the erasable area to rearrange under the influence of this voltage difference. In other words, the liquid crystal molecules 131 can transform from a planar texture to a focal conical texture. Thus, the liquid crystal molecules 131 transformed into a focal conical texture can transmit ambient light, allowing the erasable area to display a black background identical to the black substrate 30, thereby erasing the writing in the erasable area.

[0062] According to the above embodiments, since the photoelectric layer can generate photogenerated carriers after being illuminated, and the photoelectric layer is configured to charge the pixel electrode after being illuminated, the problem of the small photosensitive area of ​​the thin-film photoelectric layer 1121 can be effectively improved, thereby increasing the light utilization rate of the liquid crystal handwriting tablet. Due to the improved light utilization rate, a smaller gate turn-on voltage can be used while increasing the difference in charging rate between the light source position of the erasing device and the natural background light, thus achieving higher light erasing sensitivity and separation. Simultaneously, the structure of this liquid crystal handwriting tablet can improve light erasing performance without adding a new driving device, thereby avoiding structural complexity.

[0063] In some embodiments, the photoelectric layer 115 includes sequentially stacked P-type doped regions 1151, I-type doped regions 1152, and N-type doped regions 1153. The N-type doped region 1153 is electrically connected to the pixel electrode 111, the P-type doped region 1151 is electrically connected to the driving component 20, and the I-type doped region 1152 is configured to generate photogenerated carriers when illuminated. Specifically, the P-type doped region 1151 is doped with trivalent elements, and the N-type doped region 1153 is doped with pentavalent elements. Thus, the P-type doped region 1151, I-type doped region 1152, and N-type doped region 1153 can form a structure similar to a photovoltaic cell. Therefore, after photogenerated carriers are generated in the I-type doped region 1152 when illuminated, electrons move to the P-type doped region 1151, and holes move to the N-type doped region 1153, thereby further improving the light utilization rate of the liquid crystal writing tablet.

[0064] In some embodiments, the projection of the photoelectric layer 115 onto the second substrate 12 is located within the projection of the pixel electrode 111 onto the second substrate 12. This arrangement can reduce the influence of natural light on the photoelectric layer 115.

[0065] In some embodiments, the ratio of the area of ​​the photoelectric layer 115 to the area of ​​the pixel electrode 111 electrically connected to the photoelectric layer 115 is greater than or equal to 0.3 and less than or equal to 0.9. This setting can prevent the area of ​​the photoelectric layer 115 from being too large and affecting the wiring around the photoelectric layer 115, or prevent the area of ​​the photoelectric layer 115 from being too small and unable to effectively charge the pixel electrode 111.

[0066] In some embodiments, the material of the photoelectric layer 115 includes amorphous silicon.

[0067] In some embodiments, the second substrate 12 may be a flexible substrate, and specifically, the material of the second substrate 12 may include polyimide (PI).

[0068] In some embodiments, the liquid crystal layer 13 comprises bistable liquid crystal. Specifically, the liquid crystal layer 13 may be entirely composed of bistable liquid crystal, or it may be partially composed of bistable liquid crystal.

[0069] This application also provides a handwriting device, including any of the above-mentioned liquid crystal handwriting tablets.

[0070] The above embodiments of this application can complement each other without causing conflict.

[0071] It should be noted that the dimensions of layers and regions may be exaggerated in the accompanying drawings for clarity. Furthermore, it is understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element, or there may be intermediate layers. Additionally, it is understood that when an element or layer is referred to as being "below" another element or layer, it can be directly below the other element, or there may be more than one intermediate layer or element. Furthermore, it is also understood that when a layer or element is referred to as being "between" two layers or two elements, it can be the only layer between the two layers or two elements, or there may be more than one intermediate layer or element. Similar reference numerals throughout indicate similar elements.

[0072] The term “multiple” means two or more, unless otherwise expressly defined.

[0073] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0074] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A liquid crystal handwriting tablet, characterized in that, Includes a liquid crystal panel and a driving component electrically connected to the liquid crystal panel; The liquid crystal panel includes a first substrate and a second substrate disposed opposite to each other, and a liquid crystal layer located between the first substrate and the second substrate; the first substrate includes a plurality of block-shaped pixel electrodes, a plurality of photoelectric layers, and a plurality of thin-film transistors; the thin-film transistors are configured to conduct after being illuminated; the photoelectric layers are configured to generate photogenerated carriers after being illuminated; the pixel electrodes are electrically connected to at least one of the thin-film transistors, and the pixel electrodes are also electrically connected to at least one of the photoelectric layers; the thin-film transistors are electrically connected to the driving component, and the photoelectric layers are electrically connected to the driving component; the second substrate includes a planar common electrode; the photoelectric layer is further configured to charge the pixel electrodes after being illuminated. The driving component is configured to apply a pixel voltage to the pixel electrode when the liquid crystal writing tablet is in erase mode.

2. The liquid crystal handwriting tablet according to claim 1, characterized in that, The photoelectric layer is located on the side of the pixel electrode away from the second substrate; a gate insulating layer is provided between the photoelectric layer and the pixel electrode, and the pixel electrode is electrically connected to the photoelectric layer through a via.

3. The liquid crystal handwriting tablet according to claim 2, characterized in that, The liquid crystal handwriting tablet further includes a gate insulating layer, a conductive portion, a first trace, and a second trace; multiple first traces extend along a first direction, and multiple second traces extend along a second direction; the first direction and the second direction intersect; the thin film transistor is electrically connected to the driving component through the first trace and the second trace; The conductive portion is located between the photoelectric layer and the via. The pixel electrode is electrically connected to the conductive portion through a via, and is electrically connected to the photoelectric layer through the conductive portion; one end of the photoelectric layer is electrically connected to the second trace, and the other end of the photoelectric layer away from the second trace is electrically connected to the conductive portion; the gate insulating layer is located between the photoelectric layer and the pixel electrode, and between the second trace and the conductive portion.

4. The liquid crystal handwriting tablet according to claim 1, characterized in that, The liquid crystal handwriting tablet includes metal traces, a plurality of first traces extending along a first direction, and a plurality of second traces extending along a second direction; the first traces and the second traces intersect; the thin film transistor is electrically connected to the driving component through the first traces and the second traces; The photoelectric layer is located on the side of the pixel electrode away from the second substrate; the metal trace is located on the side of the photoelectric layer away from the pixel electrode and is electrically connected to the second trace; the photoelectric layer is electrically connected to the driving component through the metal trace.

5. The liquid crystal handwriting tablet according to claim 4, characterized in that, The photoelectric layer includes sequentially stacked P-type doped regions, I-type doped regions, and N-type doped regions. The P-type doped regions are doped with trivalent elements, and the N-type doped regions are doped with pentavalent elements. The N-type doped regions are electrically connected to the pixel electrode, and the P-type doped regions are electrically connected to the driving component. The I-type doped regions are configured to generate photogenerated carriers when exposed to light.

6. The liquid crystal handwriting tablet according to claim 5, characterized in that, The projection of the photoelectric layer on the second substrate lies within the projection of the pixel electrode on the second substrate.

7. The liquid crystal handwriting tablet according to claim 4, characterized in that, The material of the metal traces includes indium tin oxide glass.

8. The liquid crystal handwriting tablet according to claim 4, characterized in that, The material of the photoelectric layer includes amorphous silicon.

9. The liquid crystal handwriting tablet according to claim 1, characterized in that, The ratio of the area of ​​the photoelectric layer to the area of ​​the pixel electrode electrically connected to the photoelectric layer is greater than or equal to 0.3 and less than or equal to 0.

9.

10. The liquid crystal handwriting tablet according to claim 1, characterized in that, The second substrate is a flexible substrate.

11. The liquid crystal handwriting tablet according to any one of claims 1 to 9, characterized in that, The liquid crystal layer comprises bistable liquid crystal.

12. A handwriting device, characterized in that, The liquid crystal handwriting tablet includes any one of claims 1 to 10.

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