Display device

Abstract

To provide a display device capable of displaying a high-definition and high-intensity image regardless of passive drive.SOLUTION: A display device 10 is composed of a drive circuit 20, and a transparent display 30 having micro LED units U1, U2 driven by the drive circuit 20. The micro LED unit U1 includes a passive drive lower board 40, and a micro LED 42 disposed in respective intersection sections between multiple data lines and multiple scan lines formed on the passive drive lower board 40, the micro LED unit U2 includes a light-transmitting passive drive upper board 50, and a micro LED 52 disposed in each intersection sections between multiple data lines and multiple scan lines formed on the passive drive upper board 50, and the micro LED 42 is disposed in a position not overlapping with the micro LED 52.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a display device including a plurality of light-emitting elements formed on a substrate, and more particularly to a display device having passively driven micro LEDs (light-emitting diodes). [Background technology]

[0002] In recent years, micro LEDs have been developed that can display images directly from light emitting diodes. The micro LEDs are arranged two-dimensionally to correspond to each pixel, and each pixel is configured to include blue, green, and red sub-pixels. When the sub-pixels are arranged on a two-dimensional plane, the area occupied by each sub-pixel becomes large. On the other hand, when the sub-pixels are arranged within a limited area, the area of ​​each sub-pixel must be reduced, resulting in a decrease in the brightness of the sub-pixels.

[0003] The display LED stack of Patent Document 1 vertically stacks a first LED stack, a second LED stack, and a third LED stack, with the first LED stack corresponding to a red light emitting diode R, the second LED stack corresponding to a green light emitting diode G, and the third LED stack corresponding to a blue light emitting diode B, and the light emitting diodes R, G, and B corresponding to subpixels. FIG. 1 is a passive drive circuit diagram of a display LED stack. The anodes of the first to third light emitting diodes R, G, and B are commonly connected to a data wiring Vdata1, and their cathodes are connected to scan wirings Vscan1-1, Vscan1-2, and Vscan1-3, respectively, and the light emitting diodes R, G, and B in the same pixel are driven independently.

[0004] The active-drive micro LED of Patent Document 2 discloses a structure in which, as shown in FIG. 2, a semiconductor layer 120 is formed on a substrate 100 via a buffer layer 110, a thin-film transistor (TFT) including a gate electrode 140, a drain electrode 160a, and a source electrode 160b is formed on the semiconductor layer 120, a first electrode 190 connected to the source electrode 160b via a planarization layer 170 is formed, and an LED 200 including a Pn diode 250 is formed between the first electrode 190 and a second electrode 260.

[0005] Figure 3 is a circuit diagram of an active drive type. As shown in the figure, a micro LED and a drive transistor are connected in series between a supply voltage Vdd and GND, a control transistor and a storage capacitor are connected in series between a data line and GND, the gate of the control transistor is connected to a scan line, and the connection node between the control transistor and the storage capacitor is connected to the gate of the drive transistor. When the control transistor is turned on by the scan line, a data signal from the data line is applied to the gate of the drive transistor, and the LED emits light by a drive current according to the data signal. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-504752 [Patent Document 2] U.S. Patent No. 11,171,270 Summary of the Invention [Problem to be solved by the invention]

[0007] In transparent displays using micro LEDs, active driving is used to display high-definition images. However, active driving requires the formation of switching elements such as TFTs on the pixels of the substrate, which results in high initial costs for masks, etc., making it unsuitable for small-scale production. On the other hand, passive driving has the advantage of requiring fewer masks and lower initial costs because it does not require the formation of TFTs, etc. However, because it is a time-division driving method, the pixels (LEDs) are only turned on at the moment that the line is scanned in one frame, so as the number of pixels increases, the time that the pixels are energized per unit time becomes shorter, which causes a problem of reduced brightness.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS The present invention aims to solve the above-mentioned problems in the prior art and to provide a display device capable of displaying high-definition, high-brightness images even though it is passively driven. [Means for solving the problem]

[0009] The display device of the present invention includes at least a first substrate and a second substrate, the first substrate being a passive drive type substrate including a plurality of first light-emitting sections arranged in a two-dimensional shape, the first light-emitting sections being arranged at each intersection of a plurality of data lines with a plurality of scan lines, the second substrate being a passive drive type light-transmitting substrate including a plurality of second light-emitting sections arranged in a two-dimensional shape, the second light-emitting elements being arranged at each intersection of the plurality of data lines with the plurality of scan lines, the second substrate being stacked on the first substrate, the second light-emitting sections being arranged at positions that do not overlap with the first light-emitting sections.

[0010] In one embodiment, the first light-emitting units are arranged at a constant pitch in the X and Y directions, and the second light-emitting units are arranged shifted by 1 / 2 pitch in the X and Y directions with respect to the first light-emitting units. In one embodiment, a transparent protective member is provided between the first substrate and the second substrate, and the light emitted from the first light-emitting units is emitted from the surface of the second substrate through the transparent protective member. In one embodiment, the refractive index of the second substrate is greater than that of the transparent protective member, and the light emitted from the first light-emitting units is refracted in the normal direction due to the refractive index difference between the transparent protective member and the second substrate. In one embodiment, recesses are formed on the rear surface of the second substrate at positions corresponding to each of the first light-emitting units, and the first light-emitting units are accommodated in the recesses. In one embodiment, the second substrate is a transparent film substrate, and the transparent film substrate is deformed to follow the surface shape of the first light-emitting units on the first substrate. In one embodiment, the first and second light-emitting sections each correspond to a pixel (picture element), and the first and second light-emitting sections each include elements that emit R, G, and B, and the elements that emit R, G, and B correspond to sub-pixels. Effect of the Invention

[0011] According to the present invention, a second substrate having a second light-emitting section arranged in a position that does not overlap with the first light-emitting section is laminated on a first substrate having a first light-emitting section formed thereon, thereby preventing a decrease in brightness due to a shortened power supply time for the light-emitting section, and thereby obtaining a high-definition display. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a passive drive type circuit configuration. [Diagram 2] FIG. 1 is a diagram showing a cross-sectional configuration of a conventional active driving type micro LED. [Diagram 3] FIG. 1 is a diagram showing an active drive type circuit configuration. [Figure 4] 1 is a block diagram showing a configuration of a display device according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a wiring diagram of a passive drive according to an embodiment of the present invention. [Figure 6] FIG. 6(A) is a schematic cross-sectional view of a micro LED unit according to a first embodiment of the present invention, and FIG. 6(B) is a plan view perspective view showing the position of the micro LEDs when the micro LED units are stacked. [Figure 7] FIG. 11 is a schematic cross-sectional view of a micro LED unit according to a second embodiment of the present invention. [Figure 8] FIG. 11 is a schematic cross-sectional view of a micro LED unit according to a third embodiment of the present invention. [Figure 9] FIG. 13 is a schematic cross-sectional view of a micro LED unit according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The display device of the present invention relates to a display device capable of displaying a high-definition image by driving a light-emitting element (e.g., a micro LED) by passive driving. The light-emitting element is not particularly limited, but is, for example, a micro LED. It should be noted that the drawings referred to in the following description of the embodiments include exaggerated representations to facilitate understanding of the invention, and do not directly represent the shape and scale of the actual product. EXAMPLES

[0014] 4 is a block diagram showing the configuration of a display device according to an embodiment of the present invention. As shown in the figure, the display device 10 of this embodiment includes a drive circuit 20 and a transparent display 30 driven by the drive circuit 20. The transparent display 30 includes two stacked micro LED units U1 and U2, as described below, and each of the micro LED units U1 and U2 is driven independently by the drive circuit 20. The display device 10 of this embodiment realizes a high-definition and high-brightness display even though it is passively driven by configuring the transparent display 30 from two stacked micro LED units U1 and U2.

[0015] 5 is a diagram showing a passive driving circuit configuration. The micro LED unit U1 and the micro LED unit U2 have the same circuit configuration and have the passive driving circuit configuration shown in FIG.

[0016] Each of the micro LED units U1 / U2 includes a plurality of scan electrode wirings S1, S2, ..., S5, S6 extending in the row direction (X direction), a plurality of data electrode wirings D1, D2, ..., D5, D6 extending in the column direction (Y direction), and micro LEDs connected to each intersection of the scan electrode wirings and the data electrode wirings. Here, for convenience, six scan electrode wirings and data electrode wirings are illustrated, but in reality, the number of scan electrode wirings and data electrode wirings formed corresponds to the number of pixels.

[0017] The scan electrode wiring and the data electrode wiring are, for example, configured using a multi-layer wiring structure on a substrate, with the scan electrode wiring formed as the lower layer wiring, the data electrode wiring formed as the upper layer wiring, and an insulating layer formed between the lower layer wiring and the upper layer wiring. The upper and lower wiring layers may be reversed. At the intersection of the scan electrode wiring and the data electrode wiring, for example, the scan electrode wiring is electrically connected to the cathode electrode of the micro LED, and the data electrode wiring is electrically connected to the anode electrode.

[0018] The driving circuit 20 drives the scan electrode wiring in a time-division manner at a constant scan frequency. For example, when the scan electrode wiring S1 is driven, data signals are applied from the data electrode wirings D1, D2, ..., D5, D6 to each micro LED at the intersection of the scan electrode wiring S1 and the data electrode wirings D1, D2, ..., D5, D6, and the micro LEDs of this line are turned on, and then when the scan electrode wiring S2 is driven, data signals are applied from the data electrode wirings D1, D2, ..., D5, D6 to each micro LED at the intersection of the scan electrode wiring S2, and the micro LEDs of this line are turned on. In this way, one frame is displayed by sequentially driving the scan electrode wirings from S1 to S6.

[0019] In addition, the driving circuit 20 supplies data signals (driving currents) corresponding to image data to be displayed to the micro LEDs via the data electrode wirings D1, D2, ..., D5, and D6 in synchronization with the scanning of the scan electrode wirings. The micro LEDs emit light with a luminance corresponding to the applied data signal.

[0020] The driving circuit 20 is connected to each of the micro LED units U1 and U2, and can drive the micro LED units U1 and U2 simultaneously and independently, or can drive only one selected of the micro LED units U1 and U2.

[0021] In FIG. 5, one pixel (picture element) is illustrated as one LED, but when the transparent display 30 displays a color image, one pixel is composed of three sub-pixels that generate R (red), G (green), and B (blue). The configuration of the R, G, and B sub-pixels is not particularly limited, but may be composed of, for example, a diode that emits red light, a diode that emits green light, and a diode that emits blue light, or may be formed as R and G light-emitting elements using a fluorescent filter that generates red and green light from a diode that emits blue light. In the case where R, G, and B sub-pixels are included, the passive drive drives the R, G, and B sub-pixels using scan electrode wiring and data electrode wiring connected to each of the R, G, and B sub-pixels, as shown in FIG. 1. In addition, the micro LED may be, for example, a white diode that generates white light, or an infrared diode that generates infrared light.

[0022] Figure 6 is a diagram showing the configuration of a transparent display 30 for the first embodiment of the present invention, in which Figure 6(A) shows a cross section of the micro LED unit U1 taken along line AA and a cross section of the micro LED unit U2 taken along line BB, and Figure 6(B) is a planar perspective view showing the position of the micro LEDs when the micro LED units U1 / U2 are stacked.

[0023] As shown in Fig. 6(A), the micro LED unit U1 includes a passive driving lower substrate 40, a plurality of scan electrode wirings and a plurality of data electrode wirings (not shown), a plurality of micro LEDs 42 formed at the intersections of the scan electrode wirings and the data electrode wirings, and a transparent protective agent 44 covering the entire substrate including the micro LEDs 42. The passive driving lower substrate 40 is not particularly limited, but is made of, for example, a semiconductor substrate such as silicon, a glass substrate, etc. The transparent protective agent 44 is not particularly limited, but is made of a material such as PET (polyethylene terephthalate), PP (polypropylene), PVC (polyvinyl chloride), etc.

[0024] 6(B) is a plan view showing the position of the micro LED when two micro LED units U1 / U2 are stacked, and as shown in the figure, the micro LEDs 42 are arranged at a pitch P1 in the row and column directions on the substrate 40. One micro LED 42 corresponds to one pixel, and when the micro LED 42 includes R, G, and B sub-pixels, the whole including the R, G, and B sub-pixels is one pixel, and the pitch is P1.

[0025] On the other hand, the micro LED unit U2 is composed of a passive driving upper substrate 50, a plurality of scan electrode wirings and a plurality of data electrode wirings (not shown), a plurality of micro LEDs 52 formed at the intersections of the scan electrode wirings and the data electrode wirings, and a transparent protective agent 54 covering the entire surface of the substrate including the micro LEDs 52.

[0026] As shown in FIG. 6(B), the micro LEDs 52 are arranged on the substrate 50 in the row and column directions at a pitch P2 (pitch P2=pitch P1). When the micro LED unit U2 is stacked on the micro LED unit U1, the micro LEDs 52 are offset from the micro LEDs 42 by 1 / 2 pitch P1, i.e., arranged in a staggered or alternating pattern, so that the micro LED unit U2 is configured.

[0027] The passive driving upper substrate 50 is made of a light-transmitting material, such as glass or acrylic, to transmit the light emitted from the micro LED unit U1. The thickness of the passive driving upper substrate 50 is preferably as thin as possible, for example, 0.2 to 0.3 mm. This makes it possible to make the height of the micro LED 42 close to that of the micro LED 52 when the micro LED unit U2 is stacked on the micro LED unit U1, so that both are close to being formed in the same layer.

[0028] In addition, it is desirable to ensure the transparency of the stacked micro LED units U1 and U2 by minimizing the difference in refractive index between the passive drive upper substrate 50 and the transparent protective agent 44 of the micro LED unit U1. In this case, for example, the transparent protective agent 44 is made of high refractive index silicone with a refractive index of about 1.53, and the passive drive upper substrate 50 is made of glass with a refractive index of about 1.52.

[0029] Furthermore, the scan electrode wiring and the data electrode wiring formed on the passive driving upper substrate 50 may be made of a transparent electrode such as ITO so as not to block the light incident from the micro LEDs 42.

[0030] When displaying one frame, the drive circuit 20 drives the micro LED unit U1 at a scan frequency F1 in a time-division manner, and drives the macro LED unit 2 at a scan frequency F2 (F2=F1) in a time-division manner.

[0031] The light emitted from the micro LED 42 of the micro LED unit U1 is incident on the back surface of the micro LED unit U2. Since the micro LED 42 is located at a position where it does not overlap with the micro LED 52, the light emitted from the micro LED 42 passes through the passive driving upper substrate 50 and the transparent protective agent 54 and is emitted from the front surface of the micro LED unit U2. On the other hand, the light emitted from the micro LED 52 is also emitted from the front surface through the transparent protective agent 54. As a result, the transparent display 30 displays a frame image obtained by combining the frame image generated by the micro LED unit U1 and the frame image generated by the micro LED unit U2.

[0032] According to this embodiment, by stacking two micro LED units U1 / U2 so that the pixel positions do not overlap, it is possible to display a high-definition image with double the number of pixels. In addition, since the stacked micro LED units U1 / U2 are driven independently, it is possible to prevent the current flow time of the pixels per unit time from becoming shorter, suppress the decrease in brightness, and display a high-brightness image.

[0033] Next, a second embodiment of the present invention will be described. In the stacked structure of the micro LED units U1 / U2 shown in the first embodiment, the light emitted from the micro LEDs 42 on the passive driving lower substrate 40 may be diffused due to the directivity of the micro LEDs, and the diffused light may be blocked by the micro LEDs 52 on the passive driving upper substrate 50.

[0034] Therefore, in the second embodiment, the refractive index n2 of the passively driven upper substrate 50 of the micro LED unit U2 is made larger than the refractive index n1 of the transparent protective agent 44 of the micro LED unit U1 (n2>n1), so that the light emitted from the micro LED 42 is collected in the normal direction at the boundary between the transparent protective agent 44 and the passively driven upper substrate 50. In this case, it is desirable to make the thickness of the transparent protective agent 44 as thin as possible.

[0035] 7 is a diagram for explaining the second embodiment. As shown in FIG. 7(A), the transparent protective agent 44 of the micro LED unit U1 is made of low refractive index silicone (n1=1.41) as a material with a low refractive index, and the thickness is made as thin as possible to reduce the distance d from the micro LED 42 to the passively driven upper substrate 50, thereby suppressing the diffusion distance from the light emitting point of the micro LED 42. On the other hand, the passively driven upper substrate 50 is made of a material with a high refractive index (n2=1.71). Due to the difference in refractive index between the transparent protective agent 44 and the passively driven upper substrate 50, the light generated from the micro LED 42 is refracted in the normal direction at the interface (n1×sinθ1=n2×sinθ2).

[0036] Thus, according to the second embodiment, by concentrating the light emitted from the micro LED 42 in the normal direction, it is possible to prevent the light incident on the micro LED 42 from being blocked by the micro LED 52, thereby enabling a high-definition, high-brightness image to be displayed.

[0037] Next, a third embodiment of the present invention will be described. In the stacked structure of the micro LED units U1 / U2 shown in the first embodiment, it is necessary to further prevent the light emitted from the micro LED 42 from being blocked by the passive driving upper substrate 50.

[0038] Therefore, in the third embodiment, a recess or depression is processed and formed on the rear surface of the passive driving upper substrate 50 to avoid the micro LED 42, and when the micro LED unit U2 is stacked on the micro LED unit U1, the micro LED 42 is brought closer to the micro LED 52.

[0039] 8 is a diagram for explaining the third embodiment. Fig. 8(A) shows the cross section of each of the micro LED unit U1 and the micro LED unit U2 before being laminated. In the micro LED unit U1, a flexible transparent film 46 is used as a transparent protective agent to cover the entire substrate surface. The transparent film 46 has a contour that follows the unevenness of the surface of the micro LED 42 and the passive driving substrate 40.

[0040] On the other hand, in the micro LED unit U2, a plurality of holes or recesses 56 are formed on the back surface of the passively driven upper substrate 50. The recesses 56 are processed at positions corresponding to the micro LEDs 42 of the passively driven lower substrate 40, and into a shape or size that can generally accommodate the micro LEDs 42.

[0041] 8B shows a cross section of the micro LED unit U2 laminated on the micro LED unit U1. The micro LED 42 of the passive driving lower substrate 40 is accommodated in the recess 56 on the back surface of the passive driving upper substrate 50 of the micro LED unit U2 via the transparent film 46, and the area of ​​the passive driving lower substrate 40 where the micro LED 42 is not formed is generally in contact with the back surface of the passive driving upper substrate 50 via the transparent film 46.

[0042] According to the third embodiment, the micro LED 42 is accommodated in the recess 56 and brought close to the micro LED 52, thereby preventing the light emitted from the micro LED 42 from being blocked by the micro LED 52, thereby enabling a high-definition, high-brightness image to be displayed.

[0043] Next, the fourth embodiment of the present invention will be described. The fourth embodiment is a further improvement of the third embodiment, in which a transparent film substrate is used as the passive drive upper substrate, and the micro LEDs of the passive drive lower substrate and the passive drive upper substrate are arranged at approximately the same height.

[0044] 9 is a diagram for explaining the fourth embodiment. As shown in FIG. 9(A), the micro LED unit U1 is configured in the same manner as in the third embodiment, and the entire surface of the passively driven lower substrate 40 including the micro LEDs 42 is covered with a transparent film 46. On the other hand, the passively driven upper substrate 50A of the micro LED unit U2 is made of a flexible transparent film substrate, and the micro LEDs 52 are formed on the substrate.

[0045] 9(B), when the passive-drive upper substrate 50A is laminated on the passive-drive lower substrate 40, the passive-drive upper substrate 50A is deformed to follow the convex portions of the micro LEDs 42 on the surface of the passive-drive lower substrate 40. As a result, the height of the micro LEDs 42 on the passive-drive lower substrate 40 becomes approximately equal to the height of the micro LEDs 52 on the passive-drive upper substrate 50A.

[0046] 9(C), a transparent protective agent 54 is applied to the entire surface of the substrate including the micro LEDs 42 and 52. The transparent protective agent 54 may be applied to the passive drive upper substrate 50A first, or the transparent protective member 54 may be replaced with a transparent film.

[0047] According to the fourth embodiment, the passive-drive upper substrate 50A is made of a flexible transparent film substrate, and when the passive-drive upper substrate 50A is laminated on the passive-drive lower substrate 40, the passive-drive upper substrate 50A is deformed to make the height of the micro LED 42 approximately equal to that of the micro LED 52, thereby preventing the light emitted from the micro LED 42 from being blocked by the micro LED 52, and as a result, a high-definition, high-brightness display can be obtained.

[0048] In the above embodiment, two micro LED units are stacked, but the present invention is not limited to this, and three or more micro LED units can be stacked. For example, when three micro LED units are stacked, the micro LEDs of each layer are arranged so as to be shifted from each other by 1 / 3 pitch in the row and column direction. Furthermore, when four micro LED units are stacked, the micro LEDs of each layer are arranged so as to be shifted from each other by 1 / 4 pitch in the row and column direction.

[0049] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention described in the claims. [Explanation of symbols]

[0050] 10: Display device 10: Drive circuit 30: Transparent display 40: Passive drive substrate 42: Micro LED 44: Transparent protective agent 50: Passive drive upper board 52: Micro LED 54: Transparent protective agent 56: Recess U1, U2: Micro LED unit

Claims

1. at least a first substrate and a second substrate; the first substrate is a passive drive type substrate including a plurality of first light emitting units arranged two-dimensionally, the first light emitting units being arranged at intersections of a plurality of data lines with a plurality of scan lines; the second substrate is a passively driven light-transmitting substrate including a plurality of second light-emitting units arranged two-dimensionally, and in which the second light-emitting elements are arranged at the intersections of the plurality of data lines and the plurality of scan lines; A display device, comprising: a second substrate laminated on a first substrate; and a second light-emitting portion disposed at a position not overlapping with the first light-emitting portion.

2. 2. The display device according to claim 1, wherein the first light-emitting sections are arranged at a constant pitch in the X direction and the Y direction, and the second light-emitting sections are arranged shifted by 1 / 2 pitch in the X direction and the Y direction with respect to the first light-emitting sections.

3. 2. The display device according to claim 1, wherein a transparent protective member is provided between the first substrate and the second substrate, and light emitted from the first light-emitting portion is emitted from the surface of the second substrate through the transparent protective member.

4. 4. The display device according to claim 3, wherein the refractive index of the second substrate is greater than the refractive index of the transparent protective member, and the light emitted from the first light-emitting portion is refracted in the normal direction due to the difference in refractive index between the transparent protective member and the second substrate.

5. The display device according to claim 1 , wherein recesses are formed on the rear surface of the second substrate at positions corresponding to the plurality of first light-emitting portions, and the first light-emitting portions are housed in the recesses.

6. The display device according to claim 1 , wherein the second substrate is a transparent film substrate, and the transparent film substrate is deformed so as to follow a surface shape of the first light-emitting portion on the first substrate.

7. The display device according to claim 1 , wherein the first and second light-emitting portions each correspond to a pixel, the first and second light-emitting portions each include elements that emit R, G, and B, and the elements that emit R, G, and B correspond to sub-pixels.

Images