Display device

Abstract

The present invention addresses the problem of providing a display device capable of displaying a high-fineness and high-brightness image as a passive drive. A display device (10) according to the present invention is configured to include 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 driving lower substrate (40) and micro-LEDs (42) disposed at intersections of a plurality of data lines and a plurality of scanning lines formed on the passive driving lower substrate (40), and the micro-LED unit (U2) includes a light-transmissive passive driving upper substrate (50) and micro-LEDs (52) disposed at intersections of a plurality of data lines and a plurality of scanning lines formed on the passive driving upper substrate (50). The micro-LED (42) is disposed at a position that does not overlap the micro-LED (52).

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 including a passive drive type micro LED (light-emitting diode). Background Art

[0002] In recent years, micro-LEDs have been developed that can display images directly from light-emitting diodes. Micro-LEDs are arranged in two dimensions corresponding to each pixel, and each pixel is composed of blue, green, and red sub-pixels. If the sub-pixels are arranged on a two-dimensional plane, the area occupied by each sub-pixel becomes larger. On the other hand, if the sub-pixels are arranged in a limited area, the area of ​​each sub-pixel needs to be reduced, resulting in a decrease in the brightness of the sub-pixel.

[0003] In the LED stack for display of patent document 1, the 1st LED stack, the 2nd LED stack, and the 3rd LED stack are stacked in the vertical direction, the 1st LED stack corresponds to the red light-emitting diode R, the 2nd LED stack corresponds to the green light-emitting diode G, and the 3rd LED stack corresponds to the blue light-emitting diode B, and the light-emitting diodes R, G, and B correspond to sub-pixels. Figure 1 This is a circuit diagram of a passive drive type LED stack for display. The anodes of the first to third light-emitting diodes R, G, and B are commonly connected to the data wiring Vdata1, and their cathodes are respectively connected to the scanning wirings Vscan1-1, Vscan1-2, and Vscan1-3, and the light-emitting diodes R, G, and B in the same pixel are driven independently.

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

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

[0006] Prior art literature:

[0007] Patent Literature:

[0008] Patent Document 1: Japanese Patent Application Publication No. 2021-504752

[0009] Patent Document 2: U.S. Patent No. 11,171,270 Summary of the invention

[0010] Problems to be solved by the invention:

[0011] In transparent displays using micro-LEDs, active driving is used to display high-definition images. However, since active driving forms switching elements such as TFTs in the pixels of the substrate, the initial cost of masks is high and it is not suitable for small-scale production. On the other hand, passive driving does not form TFTs, so the number of masks is small and has the advantage of low initial cost. However, since it is a time-sharing driving method, the pixel (LED) is only turned on at the moment when the line is scanned in 1 frame. Therefore, if the number of pixels increases, the power-on time of the pixel per unit time becomes shorter, and there is a problem of reduced brightness.

[0012] An object of the present invention is to solve such conventional problems and to provide a display device capable of displaying high-definition and high-brightness images by passive driving.

[0013] Means used to solve the problem:

[0014] The display device involved in the present invention includes at least a first substrate and a second substrate, the first substrate includes a plurality of first light-emitting portions arranged in a two-dimensional shape, and is a passively driven substrate in which the first light-emitting portions are arranged at each intersection of a plurality of data lines and a plurality of scanning lines, the second substrate includes a plurality of second light-emitting portions arranged in a two-dimensional shape, and is a passively driven light-transmitting substrate in which a second light-emitting element is arranged at each intersection of a plurality of data lines and a plurality of scanning lines, the second substrate is stacked on the first substrate, and the second light-emitting portion is arranged at a position that does not overlap with the first light-emitting portion.

[0015] In one embodiment, the first light emitting unit is arranged at a certain pitch in the X direction and the Y direction, and the second light emitting unit is arranged to deviate from the first light emitting unit by 1 / 2 of the pitch in the X direction and the Y direction. In one embodiment, a transparent protective component is provided between the first substrate and the second substrate, and the light emitted from the first light emitting unit is emitted from the surface of the second substrate via the transparent protective component. In one embodiment, the refractive index of the second substrate is greater than the refractive index of the transparent protective component, and the light emitted from the first light emitting unit is refracted in the normal direction due to the refractive index difference between the transparent protective component and the second substrate. In one embodiment, recesses are formed on the back side of the second substrate at positions corresponding to each of the plurality of first light emitting units, and the first light emitting unit is accommodated in the recesses. In one embodiment, the second substrate is a transparent film substrate that is deformed in a manner that imitates the surface shape of the first light emitting unit on the first substrate. In one embodiment, the first and second light-emitting portions correspond to pixels, respectively, and the first and second light-emitting portions include elements emitting R, G, and B light, respectively, and the elements emitting R, G, and B light correspond to sub-pixels.

[0016] Effect of the invention:

[0017] According to the present invention, a second substrate is stacked on a first substrate having a first light-emitting portion, and the second light-emitting portion is arranged at a position of the second substrate that does not overlap with the first light-emitting portion. This prevents a reduction in brightness due to a shortened power-on time of the light-emitting portion, thereby achieving a high-definition display. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram showing a circuit configuration of a passive drive type.

[0019] Figure 2 This is a diagram showing the cross-sectional structure of a conventional active drive type micro LED.

[0020] Figure 3 It is a diagram showing a circuit configuration of an active drive type.

[0021] Figure 4 It is a block diagram showing the structure of a display device according to an embodiment of the present invention.

[0022] Figure 5 This is a wiring diagram of a passive drive according to an embodiment of the present invention.

[0023] Figure 6 (A) is a schematic cross-sectional view of a micro LED unit according to the first embodiment of the present invention. Figure 6 (B) is a plan perspective view showing the positions of micro LEDs when micro LED units are stacked.

[0024] Figure 7It is a schematic cross-sectional view of a micro LED unit according to a second embodiment of the present invention.

[0025] Figure 8 It is a schematic cross-sectional view of a micro LED unit according to a third embodiment of the present invention.

[0026] Fig. 9 It is a schematic cross-sectional view of a micro LED unit according to a fourth embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 10: Display device 20: Driving circuit

[0029] 30: Transparent display 40: Passive drive lower substrate

[0030] 42: Micro LED 44: Transparent protective agent

[0031] 50: Passive drive upper substrate 52: Micro LED

[0032] 54: Transparent protective agent 56: Concave part

[0033] U1, U2: Micro LED units DETAILED DESCRIPTION

[0034] The display device of the present invention relates to a display device capable of driving a light-emitting element (e.g., micro-LED) by passive driving and displaying a high-definition image. The light-emitting element is not particularly limited, and is, for example, a micro-LED. It should be noted that the drawings referred to in the description of the following embodiments contain exaggerated displays for the purpose of making the invention easier to understand, and do not represent the shape or proportion of the actual product as it is.

[0035] [Example]

[0036] Figure 4 : is a block diagram showing the structure of the display device involved in the embodiment of the present invention. As shown in the figure, the display device 10 of this embodiment is configured to include a driving circuit 20 and a transparent display 30 driven by the driving circuit 20. As described later, the transparent display 30 includes two stacked micro LED units U1 and U2, and each micro LED unit U1 and U2 is independently driven by the driving circuit 20. In the display device 10 of this embodiment, the transparent display 30 is formed by stacking two micro LED units U1 and U2, thereby realizing a high-definition and high-brightness display as a passive drive.

[0037] Figure 5 is a diagram showing a circuit structure of a passive drive. The circuit structure of the micro LED unit U1 is the same as that of the micro LED unit U2. Figure 5 The passive drive circuit structure is shown.

[0038] Each micro LED unit U1 / U2 includes: a plurality of scanning electrode wires S1, S2, ..., S5, S6 extending in the row direction (X direction), a plurality of data electrode wires D1, D2, ..., D5, D6 extending in the column direction (Y direction), and micro LEDs connected to each intersection of the scanning electrode wires and the data electrode wires. Here, for convenience, six scanning electrode wires and data electrode wires are illustrated, but in reality, the number of scanning electrode wires and data electrode wires corresponding to the number of pixels is formed.

[0039] The scanning electrode wiring and the data electrode wiring are formed, for example, using a multi-layer wiring structure on the substrate, with the scanning electrode wiring formed as the lower wiring, and the data electrode wiring formed as the upper wiring, and an insulating layer formed between the lower wiring and the upper wiring. The upper and lower wiring layers may also be opposite. At the intersection of the scanning electrode wiring and the data electrode wiring, for example, the scanning 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.

[0040] The driving circuit 20 drives the scanning electrode wiring in a time-sharing manner at a certain scanning frequency. For example, if the scanning electrode wiring S1 is driven, the data signal is applied from the data electrode wiring D1, D2, ..., D5, D6 to each micro LED at the intersection of the scanning electrode wiring S1 and the data electrode wiring D1, D2, ..., D5, D6, and the micro LED of the line is lit. Next, if the scanning electrode wiring S2 is driven, the data signal is applied from the data electrode wiring D1, D2, ..., D5, D6 to each micro LED at the intersection of the scanning electrode wiring S2, and the micro LED of the line is lit. By driving the scanning electrode wiring sequentially from S1 to S6 in this way, one frame of display is performed.

[0041] In synchronization with scanning of the scanning electrode wiring, 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. The micro LEDs emit light at brightness corresponding to the applied data signals.

[0042] The driving circuit 20 is connected to the micro LED units U1 and U2 , respectively, and can drive the micro LED units U1 and U2 independently and simultaneously, or can drive only a selected one of the micro LED units U1 and U2 .

[0043] Figure 5One pixel is exemplified 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 composition of the R, G, and B sub-pixels is not particularly limited. For example, they can be composed of a diode that emits red light, a diode that emits green light, and a diode that emits blue light, or they can be formed by using a fluorescent filter that generates red and green from a diode that emits blue light to form R and G light-emitting elements. In the case of sub-pixels including R, G, and B, passive driving such as Figure 1 As shown, the sub-pixels of R, G, and B are driven using scanning electrode wiring and data electrode wiring connected to the sub-pixels of R, G, and B. In addition, the micro LED may be, for example, a white diode that generates white light or an infrared diode that generates infrared light.

[0044] Figure 6 1 is a diagram showing the structure of a transparent display 30 according to a first embodiment of the present invention. Figure 6 (A) represents the AA line cross section of the micro LED unit U1 and the BB line cross section of the micro LED unit U2. Figure 6 (B) is a plan perspective view showing the positions of micro LEDs when the micro LED units U1 / U2 are stacked.

[0045] like Figure 6 As shown in (A), the micro LED unit U1 is composed of: a passively driven lower substrate 40, a plurality of scanning electrode wirings and a plurality of data electrode wirings not shown in the figure, a plurality of micro LEDs 42 formed at the intersection of the scanning electrode wirings and the data electrode wirings, and a transparent protective agent 44 covering the entire substrate including the micro LEDs 42. The passively driven lower substrate 40 is not particularly limited, and is composed of, for example, a semiconductor substrate such as silicon, a glass substrate, etc. In addition, the transparent protective agent 44 is not particularly limited, and is composed of materials such as PET (polyethylene terephthalate), PP (polypropylene), and PVC (polyvinyl chloride).

[0046] Figure 6 (B) is a plan view showing the position of the micro LEDs when two micro LED units U1 / U2 are stacked. As shown in the figure, the micro LEDs 42 are arranged at a pitch P1 along the row and column directions on the substrate 40. One micro LED 42 corresponds to one pixel. 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.

[0047] On the other hand, the micro LED unit U2 is constructed to include: a passively driven upper substrate 50, a plurality of scanning electrode wirings and a plurality of data electrode wirings not shown here, a plurality of micro LEDs 52 formed at the intersection of the scanning 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.

[0048] Micro LED52 Figure 6 As shown in (B), the micro LED units U2 are arranged with a pitch P2 along the row direction and the column direction on the substrate 50 (pitch P2 = pitch P1). When the micro LED unit U2 is stacked on the micro LED unit U1, the micro LED unit U2 is constructed in a manner that the micro LED52 deviates from the micro LED42 by 1 / 2 of the pitch P1, that is, in a staggered or staggered arrangement.

[0049] The passive drive upper substrate 50 is made of a light-transmitting material, such as glass or acrylic, in order to transmit the light emitted from the micro LED unit U1. The thickness of the passive drive upper substrate 50 is preferably as thin as possible, for example, 0.2 to 0.3 mm. Thus, when the micro LED unit U2 is stacked on the micro LED unit U1, the height of the micro LED 42 is close to the height of the micro LED 52, close to the situation where the two are formed on the same layer.

[0050] In addition, it is preferred to minimize the refractive index difference between the passive drive upper substrate 50 and the transparent protective agent 44 of the micro LED unit U1, thereby ensuring the transparency of the stacked micro LED units U1 and U2. In this case, for example, the transparent protective agent 44 is made of high-refractive silicone with a refractive index of approximately 1.53, and the passive drive upper substrate 50 is made of glass with a refractive index of approximately 1.52.

[0051] Furthermore, the scanning electrode wiring and the data electrode wiring formed on the passive drive upper substrate 50 may also be formed of transparent electrodes such as ITO so as not to block the light incident from the micro LEDs 42 .

[0052] When displaying one frame, the driving circuit 20 drives the micro LED unit U1 in a time-division manner at the scanning frequency F1 , and also drives the micro LED unit U2 in a time-division manner at the scanning frequency F2 ( F2 = F1 ).

[0053] The light emitted from the micro LED 42 of the micro LED unit U1 is incident from the back side of the micro LED unit U2. The micro LED 42 is located at a position that does not overlap with the micro LED 52, so the light emitted from the micro LED 42 transmits the passive drive upper substrate 50 and the transparent protective agent 54, and is emitted from the surface of the micro LED unit U2. On the other hand, the light emitted from the micro LED 52 is also emitted from its surface via the transparent protective agent 54. Thus, the transparent display 30 displays a frame image obtained by synthesizing the frame image generated by the micro LED unit U1 and the frame image generated by the micro LED unit U2.

[0054] According to this embodiment, by stacking two micro LED units U1 / U2 in a manner that the positions of pixels do not overlap, a high-definition image can be displayed that actually doubles the number of pixels. In addition, since the stacked micro LED units U1 / U2 are driven independently, it is possible to prevent the power-on time of the pixel per unit time from being shortened, suppress the brightness reduction, and display a high-brightness image.

[0055] Next, the second embodiment of the present invention is described. In the stacked structure of the micro LED unit U1 / U2 shown in the first embodiment, due to the directivity of the micro LED, it is possible that the light emitted from the micro LED 42 of the passively driven lower substrate 40 is diffused, and the diffused light is blocked by the micro LED 52 of the passively driven upper substrate 50.

[0056] Therefore, in the second embodiment, the refractive index n2 of the passive driving 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 focused in the normal direction at the boundary between the transparent protective agent 44 and the passive driving upper substrate 50. At this time, it is preferred to make the thickness of the transparent protective agent 44 as thin as possible.

[0057] Figure 7 2 is a diagram for explaining the second embodiment. Figure 7 As shown in (A), the transparent protective agent 44 of the micro LED unit U1 is made of low refractive silicone (n1=1.41) as a low refractive index material, and its thickness is made as thin as possible to reduce the distance d from the micro LED 42 to the passive drive upper substrate 50, thereby suppressing the diffusion distance from the light emitting point of the micro LED 42. On the other hand, the passive drive upper substrate 50 is made of a high refractive index material (n2=1.71). Due to the refractive index difference between the transparent protective agent 44 and the passive drive upper substrate 50, the light emitted from the micro LED 42 is refracted in the normal direction at the interface (n1×sinθ1=n2×sinθ2).

[0058] As described above, according to the second embodiment, by focusing the light emitted from the micro LED 42 in the normal direction, it is possible to suppress the light incident from the micro LED 42 from being blocked by the micro LED 52 , thereby enabling a high-definition and high-brightness image to be displayed.

[0059] 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 LEDs 42 from being blocked by the passive drive upper substrate 50 .

[0060] Therefore, in the third embodiment, a recess or depression is formed on the back surface of the passive driving upper substrate 50 to avoid the micro LED 42 , so that the micro LED 42 is closer to the micro LED 52 when the micro LED unit U2 is stacked on the micro LED unit U1 .

[0061] Figure 8 It is a diagram for explaining the third embodiment. Figure 8 (A) shows the cross-section of each of the micro LED unit U1 and the micro LED unit U2 before lamination. In the micro LED unit U1, a flexible transparent film 46 is used as a transparent protective agent to cover the entire surface of the substrate. The transparent film 46 has a contour that imitates the concave and convex surfaces of the micro LED 42 and the passive drive substrate 40.

[0062] On the other hand, in the micro LED unit U2, a plurality of holes or recesses 56 are formed on the back of the passive drive upper substrate 50. The recesses 56 are processed into a shape or size that can substantially accommodate the micro LEDs 42 at positions corresponding to the micro LEDs 42 of the passive drive lower substrate 40.

[0063] Figure 8 (B) shows a cross section when the micro LED unit U2 is stacked onto the micro LED unit U1. The micro LED 42 of the passively driven lower substrate 40 is accommodated in the recess 56 on the back side of the passively driven upper substrate 50 of the micro LED unit U2 via the transparent film 46. In addition, the area of ​​the passively driven lower substrate 40 where the micro LED 42 is not formed is roughly in contact with the back side of the passively driven upper substrate 50 via the transparent film 46.

[0064] According to the third embodiment, by accommodating micro LED 42 in recess 56 and bringing micro LED 42 and micro LED 52 close to each other, it is possible to prevent light emitted from micro LED 42 from being blocked by micro LED 52 , thereby displaying a high-definition and high-brightness image.

[0065] Next, the fourth embodiment of the present invention is described. The fourth embodiment is an improved embodiment of the third embodiment, using a transparent film substrate as the passive drive upper substrate so that the micro LEDs of the passive drive lower substrate and the micro LEDs of the passive drive upper substrate are substantially the same height.

[0066] Fig. 9 1 is a diagram for explaining the fourth embodiment. Fig. 9 As shown in (A), the micro LED unit U1 is constructed in the same manner as in the third embodiment, and the entire surface of the passively driven lower substrate 40 including the micro LED 42 is covered by a transparent film 46. On the other hand, the passively driven upper substrate 50A of the micro LED unit U2 is composed of a flexible transparent film substrate, on which the micro LED 52 is formed.

[0067] like Fig. 9 As shown in (B), when the passively driven upper substrate 50A is stacked on the passively driven lower substrate 40, the passively driven upper substrate 50A is deformed in a manner that imitates the convex portion of the micro LED 42 on the surface of the passively driven lower substrate 40. As a result, the height of the micro LED 42 of the passively driven lower substrate 40 becomes substantially equal to the height of the micro LED 52 of the passively driven upper substrate 50A.

[0068] Next, if Fig. 9 As shown in (C), a transparent protective agent 54 is applied to the entire surface of the substrate including the micro LEDs 42 and 52. In addition, 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.

[0069] According to the fourth embodiment, the passively driven upper substrate 50A is composed of a flexible transparent film substrate. When the passively driven upper substrate 50A is stacked on the passively driven lower substrate 40, the passively driven upper substrate 50A is deformed to make the height of the micro LED 42 approximately equal to the height of the micro LED 52, thereby preventing the light emitted from the micro LED 42 from being blocked by the micro LED 52. As a result, a high-definition and high-brightness display can be obtained.

[0070] In the above embodiment, an example of stacking two micro LED units is shown, but the present invention is not limited thereto, and three or more micro LED units can also be stacked. For example, when three micro LED units are stacked, the micro LEDs of each layer are configured to deviate from each other by 1 / 3 of the pitch in the matrix direction. Furthermore, when four micro LED units are stacked, the micro LEDs of each layer are configured to deviate from each other by 1 / 4 of the pitch in the matrix direction.

[0071] 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 can be made within the scope of the gist of the invention described in the claims.

Claims

1. A display device comprising at least a first substrate and a second substrate, in, The first substrate includes a plurality of first light emitting portions arranged in a two-dimensional shape, and the first substrate is a passive driving type substrate in which the first light emitting portions are arranged at respective intersections of a plurality of data lines and a plurality of scanning lines. The second substrate includes a plurality of second light emitting portions arranged in a two-dimensional shape, and the second substrate is a passively driven light-transmissive substrate in which second light emitting elements are arranged at respective intersections of a plurality of data lines and a plurality of scanning lines. The second substrate is stacked on the first substrate, and the second light emitting section is arranged at a position not overlapping with the first light emitting section.

2. The display device according to claim 1, in, The first light emitting portions are arranged at a constant pitch in the X direction and the Y direction, and the second light emitting portions are arranged to be offset by 1 / 2 of the pitch with respect to the first light emitting portions in the X direction and the Y direction.

3. The display device according to claim 1, in, A transparent protective member is provided between the first substrate and the second substrate, and light emitted from the first light emitting section is emitted from the surface of the second substrate via the transparent protective member.

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

5. The display device according to claim 1, in, On the back surface of the second substrate, recessed portions are formed at positions corresponding to the respective first light emitting portions of the plurality of first light emitting portions, and the first light emitting portions are housed in the recessed portions.

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

7. The display device according to claim 1, in, The first light-emitting portion and the second light-emitting portion correspond to pixels, respectively. The first light-emitting portion and the second light-emitting portion include elements that emit R, G, and B light, respectively. The elements that emit R, G, and B light correspond to sub-pixels.

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