Polymer dispersed liquid crystal display panel and display device

Abstract

This invention relates to the field of display technology, specifically to a polymer dispersed liquid crystal display panel and display device, comprising at least two transparent electrode layers and at least one PDLC material thin layer. Its cross-sectional structure, from top to bottom, includes a first electrode layer, a PDLC material thin layer, and a second electrode layer. The conductive plating of the first and second electrode layers is laser-etched to cut off the conductive plating of the pattern area to be displayed, the electrode lead area, the accompanying electrode area, and other areas on the electrode layers. The outer contours of the first and second electrode layers must completely overlap. This invention, through ingenious design of the pattern, electrode leads, and accompanying leads in the first and second electrode layers, ensures that each electrode lead has an accompanying lead in the opposing electrode layer. These accompanying leads are not connected to the pattern in the opposing electrode layer and are only used to eliminate the display of the electrode leads, effectively controlling the display effect within the internal contour area.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more specifically, to a polymer-dispersed liquid crystal display panel and display device. Background Technology

[0002] Since its invention, polymer-dispersed liquid crystal (PDLC) materials, in the form of liquid crystal dimming films, have been widely used in architectural and automotive glass. They possess the properties of being transparent when electrically conductive and fogging when electrically deactivated, providing functions such as privacy protection and glare shielding.

[0003] The liquid crystal dimming film consists of two opposing transparent conductive films sandwiching PDLC material. The thickness of the PDLC material layer is typically around 12–20 micrometers. The transparent conductive films are generally made of indium tin oxide (ITO), but organic conductive coatings (PEDOT), silver nanowire coatings, or metal coatings are also used. Within the PDLC material layer, nematic liquid crystals are stored in a polymer matrix in the form of dispersed or interconnected liquid droplets. The polymer matrix also serves to bond the two transparent conductive films together.

[0004] PDLC materials can respond to electric field strength. Ordinary PDLC materials, sometimes referred to as positive PDLC materials, exhibit a decrease in haze as the applied electric field intensifies. Once the electric field strength reaches a certain value, the haze stops changing. Conversely, without an applied electric field, the material is transparent; when an electric field is applied, the haze increases with increasing field strength. These PDLC materials are called negative or inverse PDLC materials. Their characteristic voltage is defined exactly in reverse. It is particularly important to note that PDLC materials and devices must be driven by an alternating electric field, and the driving power supply must be an alternating current (AC) power source.

[0005] The industry has been attempting to develop display devices based on PDLC materials and has developed various implementation processes. As described in patent CN110471206A, a laser is used to penetrate the conductive film matrix on a formed thin film, ablating and cutting the conductive coating to obtain the designed display pattern. Alternatively, as described in patent CN108445667A, a dot matrix pattern is displayed by pre-etching (laser etching or chemical etching) the transparent conductive film, using a row-column interlacing method. Or, as described in patent CN106103022B, the transparent conductive film is destructively bent, causing the conductive coating to break in a predetermined direction to obtain the designed stripe pattern.

[0006] The above processes are all aimed at achieving the static pattern display of PDLC. However, Patent CN110471206A fails to solve the lead problem of the PDLC display panel. When driving the pattern, the leads will also appear; this process solution cannot achieve the complete display of closed patterns (such as circles, squares, the letter A, the Chinese character "field", etc.). It is necessary to design openings for each closed area of the pattern one by one, which has a negative impact on the pattern design effect; in addition, the residues after laser ablation cannot be separated from the film, which is likely to cause local short circuits. In severe cases, the entire film will be burned. The row-column cross driving method adopted by Patent CN108445667A is similar to TN and STN display technologies and is originally based on the threshold voltage in the photoelectric response characteristics of liquid crystal materials. However, due to the significant differences in the photoelectric response characteristics between PDLC materials and liquid crystal materials, there is a problem of semi-display in non-selected areas. Patent CN106103022B can only achieve striped patterns, and the pattern edges are irregular.

[0007] For more technical solutions, such as the implementation method of using a traditional 8-segment LCD (Fundamentals and Applications of Liquid Crystal Electronics, Akio Sasaki, Science Press, page 98), it is necessary to perform regional clearing on the conductive layer. Since the presence or absence of the conductive layer itself has a difference in light transmittance, the PDLC display achieved by this technical solution shows the pre-etched pattern even without driving; at the same time, since the conductive layer is regionally cleared, the entire display panel cannot be powered on and driven, and thus the effect of full transparency of the display cannot be achieved.

[0008] In addition, although TFT display technology can be applied to PDLC display panels, it is expensive and difficult to be applied to small-batch customized products. Summary of the Invention

[0009] Aiming at the defects in the prior art, the present invention provides a polymer-dispersed liquid crystal display panel and a display device. The display device can achieve four states: full-panel fogging, full-panel transparency, transparency of the pattern while the rest is fogged, and fogging of the pattern while the rest is transparent; and can achieve the effect that the pattern is centered in the display screen and no electrode leads are shown around; and can achieve the complete display of closed patterns (such as circles, squares, the letter A, the Chinese character "field", etc.) without making openings on the pattern. When the display panel is in the states of full-panel fogging and full-panel transparency, the image of the electrode will not appear.

[0010] The present invention is achieved through the following technical solutions:

[0011] A polymer-dispersed liquid crystal display panel includes at least two transparent electrode layers and at least one thin layer of PDLC material, and displays simple and complex pattern contents through the visual contrast formed by the change in the haze of the PDLC material.

[0012] The simple patterns described above specifically refer to simply connected figures in the Euclidean plane in a topological sense, regardless of the complexity of their outlines. Simply put, these figures have no other outlines within their closed outlines. Examples include a circle or a bold letter C. Complex patterns, on the other hand, specifically refer to non-simply connected figures in the Euclidean plane in a topological sense. Simply put, these figures have one or more other closed outlines within their outward-facing closed outlines. Examples include a bold Arabic numeral 0 or a bold letter B.

[0013] A further improvement of the present invention is that the display panel is rectangular and includes: a display area for displaying images and an electrode area for distributing electrode lead connections. The electrode leads are specifically strip-shaped or ribbon-shaped conductive areas extending from the pattern electrode within the conductive electrode layer to the side of the display panel for supplying power to the pattern area.

[0014] The display panel includes, from top to bottom, a first electrode layer, a PDLC material thin layer, and a second electrode layer; wherein: the conductive plating layer of the first electrode layer is laser-etched to cut off the conductive plating layer of the pattern to be displayed and the electrode lead area from other areas of the electrode layer; the conductive plating layer of the second electrode layer is also laser-etched to cut off the conductive plating layer of the pattern to be displayed and the electrode lead area from other areas of the electrode layer.

[0015] For the aforementioned simple pattern, when the first electrode layer and the second electrode layer are placed facing each other, the outer contours of the pattern can overlap; moreover: each independent pattern in the first electrode layer has a connected electrode lead; on the second electrode layer, corresponding to the electrode lead area of ​​the first electrode layer, there is a companion lead with the same shape that can overlap with the electrode lead of the first electrode layer, but this companion lead is disconnected from the pattern electrode on the second electrode layer by laser etching; similarly, each independent pattern in the second electrode layer has a connected electrode lead; similarly, on the first electrode layer, corresponding to the electrode lead area of ​​the second electrode layer, there is a companion lead with the same shape that can overlap with the electrode lead of the second electrode layer, but this companion lead is disconnected from the pattern electrode on the first electrode layer by laser etching.

[0016] For the aforementioned complex patterns, when the first and second electrode layers are placed facing each other, the outer contours of the patterns can overlap; moreover: on the first electrode layer, for each independent complex pattern, a portion of the inner closed contour line is retained, and additional line segments are added to both ends of the line segments to connect to the outer contour, thereby obtaining two or more simple patterns; on the second electrode layer, for each independent complex pattern, the remaining line segments of each inner closed contour line are retained, and additional line segments are added to both ends of the line segments to connect to the outer contour, and the added line segments overlap with the added line segments of the first electrode layer, thereby obtaining two or more simple patterns; each independent pattern of the first electrode layer has There is a connected electrode lead; on the second electrode layer, corresponding to the electrode lead area of ​​the first electrode layer, there is a companion lead with the same shape that can overlap with the electrode lead of the first electrode layer, but this companion lead is disconnected from the pattern electrode on the second electrode layer by laser etching; similarly, each independent pattern on the second electrode layer has a connected electrode lead; similarly, on the first electrode layer, corresponding to the electrode lead area of ​​the second electrode layer, there is a companion lead with the same shape that can overlap with the electrode lead of the second electrode layer, but this companion lead is disconnected from the pattern electrode on the first electrode layer by laser etching.

[0017] In a further improvement of the present invention, the PDLC thin layer is made of either a positive PDLC material or a negative PDLC material.

[0018] A further improvement of the present invention is that the first electrode layer and the second electrode layer are made of transparent electrode material. The transparent electrode material is a flexible transparent conductive film or a transparent conductive glass with a certain rigidity. Its coating can be one or more of indium tin oxide, zinc oxide, zinc tin oxide, silver nanowires, silver, copper, aluminum, or graphene. Its substrate can be PET polyester film, PEN polyester film, glass, PMMA board, PC board, etc.

[0019] Furthermore, the present invention also provides a display device comprising the polymer-dispersed liquid crystal display panel described above. This device is capable of driving the panel to display desired pattern effects according to a programmed sequence.

[0020] The beneficial effects of this invention are as follows: Through the ingenious design of the patterns, electrode leads, and accompanying leads in the first and second electrode layers, each electrode lead is accompanied by an accompanying lead in the opposing electrode layer. These accompanying leads are not connected to the patterns in the opposing electrode layer and are used only to eliminate the display of the electrode leads. For complex graphics, both the first and second electrode layers have a simple pattern segmented on one side that can encompass the internal contour area. The overlapping simple patterns on both sides form an alternating electrode structure within the internal contour area, thus effectively controlling the display effect within the internal contour area. Attached Figure Description

[0021] Figure 1 This is a top view of the polymer-dispersed liquid crystal display panel described in Embodiments 1 and 2 of the present invention.

[0022] Figure 2 This is a cross-sectional view of the polymer-dispersed liquid crystal display panel described in Embodiments 1 and 2 of the present invention.

[0023] Figure 3 This is a schematic diagram of the electrode etching scheme for electrode layer 1 and electrode layer 2 in Embodiment 1 of the present invention.

[0024] Figure 4 This is a schematic diagram of the driving effect of the panel in Embodiment 1 of the present invention.

[0025] Figure 5 This is a schematic diagram of the electrode etching scheme for electrode layer 1 and electrode layer 2 in Embodiment 2 of the present invention.

[0026] Figure 6 This is a schematic diagram of the driving effect of the panel in Embodiment 2 of the present invention.

[0027] Figure 7 This is a schematic diagram of the display structure and driving effect in Embodiment 3 of the present invention.

[0028] Figure 8 This is a schematic diagram of the display structure and driving effect in Embodiment 3 of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that the PDLC thin-layer materials used in the embodiments of the present invention are all made of positive PDLC material. For ease of description, in the embodiments, when indicating the driving state, the number 1 represents a high level and the number 0 represents a low level.

[0031] Example 1:

[0032] This invention provides a polymer-dispersed liquid crystal display panel, which includes two electrode layers and a thin PDLC material layer. The display panel is rectangular, such as... Figure 1 As shown, it includes: a pattern display area 110, an electrode lead distribution area 120, and an electrode pin area 130. Furthermore, the display panel's cross-sectional structure is configured with three layers, as shown... Figure 2 As shown, it includes, from top to bottom: a first electrode layer 210, a PDLC material thin layer 220, and a second electrode layer 230. The first electrode layer 210 includes a conductive dielectric plating layer 211; the second electrode layer 230 includes a conductive dielectric plating layer 231.

[0033] In this embodiment, the pattern display area is displayed as a bold uppercase letter C. To display this pattern effect, the etching effect of the conductive plating layer on the electrode layer is as follows: Figure 3 As shown in the diagram. The first electrode layer 311 is oriented with the conductive plating layer facing away from the observer's line of sight, while the second electrode layer 312 is oriented with the conductive plating layer facing the observer's line of sight. In the first electrode layer 311, the conductive plating layer 321 outside the pattern is completely preserved without any surface etching. In the first electrode layer 311, a laser etching process is used to separate the pattern 322, electrode lead 323, and associated lead 324 areas according to the solid lines shown in the diagram. The width of the etching lines is 10–50 micrometers. The areas crossing the etching lines are not conductive to each other. In the first electrode layer 311, electrode lead 323 is connected to pattern 322; associated lead 324 is not connected to pattern 322. In the first electrode layer 311, electrode pins 341, 342, and 343 are coated with silver paste. Pin 341 is connected to associated lead 324; pin 342 is connected to electrode lead 323; pin 343 is connected to the conductive plating layer 321 outside the pattern. In the second electrode layer 312, the situation is the same as described in the first electrode layer 311, except that the line positions are adjusted. Specifically, the conductive plating layer 327 outside the pattern is completely retained without any surface etching. Electrode leads 344, 345, and 346 on the second electrode layer are coated with silver paste. 325 is the electrode lead, and 326 is the accompanying lead.

[0034] To demonstrate the effectiveness of the display panel provided in the embodiments of the present invention, the control method of the display panel will be described below.

[0035] Table 1. Truth table of voltage levels for electrode pins 341-346

[0036]

[0037] The final display effect of the display panel in this embodiment of the invention is as follows: Figure 4 As shown. Where: 411 is the pattern display area, 412 is the electrode distribution area and electrode pin wiring area, which is covered by the outer casing. 401 shows a full-area atomization effect, where the pattern blends seamlessly with the background and is visually indistinguishable. 402 shows an effect where the pattern is atomized while the remaining parts are transparent. 403 shows an effect where the pattern is transparent while the remaining parts are atomized. 404 shows a full-area transparent effect.

[0038] Example 2:

[0039] This invention provides a polymer-dispersed liquid crystal display panel. The display panel includes two electrode layers and a thin PDLC material layer. Optionally, the display panel is rectangular, such as... Figure 1 As shown. It includes: a pattern display area 110, an electrode lead distribution area 120, and an electrode pin area 130. Furthermore, the display panel's cross-sectional structure is configured as a three-layer structure, as shown... Figure 2 As shown, it includes, from top to bottom: a first electrode layer 210, a PDLC material thin layer 220, and a second electrode layer 230. Specifically, 211 is the conductive dielectric plating layer of the first electrode layer, belonging to the first electrode layer; 231 is the conductive dielectric plating layer of the second electrode layer, belonging to the second electrode layer. In this embodiment, the pattern display area is displayed as a bold uppercase letter D. To display this pattern effect, the etching effect of the conductive plating layer on the electrode layer is as follows... Figure 5 As shown in the diagram. Specifically, the first electrode layer 511 is oriented with the conductive plating layer facing away from the observer's line of sight, while the second electrode layer 512 is oriented with the conductive plating layer facing the observer's line of sight. In the first electrode layer 511, the conductive plating layer 521 outside the pattern is completely preserved without any surface etching. In the first electrode layer 511, a laser etching process is used to separate the areas of pattern 522, pattern 523, electrode lead 531, electrode lead 533, associated lead 532, and associated lead 534 from each other, as shown by the solid lines in the diagram. The width of the etching lines is 10–50 micrometers. The conductive plating layers are not electrically connected across the etching lines.

[0040] In the first electrode layer 511, electrode lead 532 is connected to pattern 523; electrode lead 533 is connected to pattern 522; associated lead 532 is not connected to pattern 523; associated lead 534 is not connected to pattern 522; and pattern 522 is not connected to pattern 523. In the first electrode layer 511, electrode pins 541, 542, 543, 544, and 551 are coated with silver paste. Pin 541 is connected to associated lead 534; pin 542 is connected to electrode lead 533; pin 543 is connected to associated lead 532; pin 544 is connected to electrode lead 531; and pin 551 is connected to the conductive plating layer 521 outside the pattern. In the second electrode layer 512, the situation is the same as described in the first electrode layer 511, except that the line positions are adjusted. Wherein: 525 and 526 are patterned areas; 545, 546, 547, 548, and 552 are electrode leads on the second electrode layer, coated with silver paste. 536 and 538 are electrode leads, and 535 and 537 are associated leads.

[0041] It is worth noting that in this embodiment, in order to effectively control the central blank area of ​​the letter D, the letter D is first divided into left and right parts along the left vertical line. In the first electrode layer 511, the central blank area is connected to the right half of the pattern; in the second electrode layer 512, the central blank area is connected to the left half of the pattern. By coordinating the control codes of the left and right halves, the high and low levels of the central blank area can be controlled.

[0042] To demonstrate the effectiveness of the display panel provided in the embodiments of the present invention, the control method of the display panel will be described below.

[0043] Table 2. Truth table of voltage levels for electrode pins 541-552

[0044]

[0045] The final display effect of the display panel in this embodiment of the invention is as follows: Figure 6 As shown. Where: 611 is the pattern display area. 612 is the electrode distribution area and electrode pin wiring area, concealed by the outer casing. 601 shows a full-area atomization effect, where the pattern blends seamlessly with the background, making it visually indistinguishable. 602 shows an effect where the pattern is atomized while the remaining parts are transparent. 603 shows an effect where the pattern is transparent while the remaining parts are atomized. 604 shows a full-area transparent effect.

[0046] Example 3:

[0047] This invention also provides a display device, including the polymer-dispersed liquid crystal display panel described above. For example, the display device can be a clock display that combines seven-segment display with fixed text. Figure 7 and Figure 8 As shown. 711 is the display area, 712 is the electrode distribution area and electrode pin wiring area, and 713 is the digital control circuit area. 701 shows the effect of pattern atomization while the rest is transparent, and 702 shows the effect of pattern transparency while the rest is atomized. Full-area atomization and full-area transparency effects are omitted here. Note that the seven-segment code and colon can be considered as seven independent simple patterns, and the text is treated as simple and complex patterns respectively according to its topological structure.

[0048] In this invention, the terms "first," "second," and "third" are used only to describe the purpose and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0049] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A polymer-dispersed liquid crystal display panel, characterized in that, The display panel comprises at least two transparent electrode layers and at least one PDLC material thin layer, used to display simple and complex patterns. Its cross-sectional structure, from top to bottom, includes a first electrode layer, a PDLC material thin layer, and a second electrode layer. The conductive plating of the first and second electrode layers is laser-etched to cut off the conductive plating of the pattern area to be displayed, the electrode lead area, the accompanying electrode area, and other areas on the electrode layers. The outer contours of the first and second electrode layers must completely overlap. The display panel also includes electrode leads, which connect from the pattern area within the electrode layers to the side of the display panel. These leads are strip-shaped or ribbon-shaped conductive areas used to power the pattern area. The display panel also includes accompanying electrode areas, specifically areas within the electrode layers that completely overlap with the electrode lead areas within the opposing electrode layers. The domains are not connected. On the first electrode layer, a portion of the line segment of each internal closed contour line is retained, and line segments are added to both ends of the line segment to connect to the outer contour, thereby obtaining two or more simple patterns. On the second electrode layer, the remaining line segment of each internal closed contour line is retained, and line segments are added to both ends of the line segment to connect to the outer contour, and the added line segments completely overlap with the added line segments of the first electrode layer, thereby obtaining two or more simple patterns. On the first and second electrode layers, for each separated independent pattern, there is at least one led-out electrode lead. On the first and second electrode layers, corresponding to the electrode lead area of ​​the counter electrode layer, there is a companion lead with the same shape that can overlap with the electrode lead of the counter electrode layer. This companion lead is disconnected from the pattern electrode on this electrode layer by laser etching.

2. The polymer-dispersed liquid crystal display panel according to claim 1, characterized in that: The PDLC material thin layer is achieved using either positive or negative PDLC.

3. The polymer-dispersed liquid crystal display panel according to claim 2, characterized in that: The first electrode layer and the second electrode layer are made of transparent electrode material.

4. The polymer-dispersed liquid crystal display panel according to claim 3, characterized in that: The transparent electrode material is a flexible transparent conductive film or a transparent conductive glass with a certain rigidity, wherein: its coating is one or more of indium tin oxide, zinc oxide, zinc tin oxide, silver nanowires, silver, copper, aluminum, or graphene; its substrate is PET polyester film, PEN polyester film, glass, PMMA board, or PC board.

5. A display device, characterized in that, Includes the polymer-dispersed liquid crystal display panel as described in claim 4.

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