Transparent display

Abstract

To provide a transparent display capable of reducing a decrease in a drive voltage when a drive current is increased and avoiding prominence of wiring for allowing a drive current to flow.SOLUTION: A transparent display 100 includes: a board 10 that is formed from a transparent material and has multiple divided pixel areas 10a; multiple micro LEDs 12r, 12g, 12b that are disposed in each of the multiple pixels areas 10a and emits light having each light from among multiple colors; wiring for applying a common drive voltage to each of the multiple micro LEDs 12r, 12g, 12b included in the pixel areas 10a aligned in a line from among the multiple pixel areas 10a; and a cathode driver 20 for generating a common drive voltage and applying it to the wiring. The wiring has cathode wires 14r, 14g, 14b as multiple branching wires for separately applying a common drive voltage to the multiple micro LEDs 12r, 12g, 12b included in the same pixel area 10a.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a transparent display using micro LEDs. [Background technology]

[0002] There are several methods to realize a transparent display, one of which is the use of micro LEDs. Micro LEDs are inorganic EL (Electro Luminescence) devices, and have the advantage of being highly reliable.

[0003] In a transparent display, RGB three-color micro LEDs that are smaller than the size of each pixel (for example, 100 μm or less on a side) are arranged on the surface of each pixel on a substrate made of transparent material. The total number of these LEDs is the resolution x 3, and for example, in the case of full high definition (FHD), there will be as many as 2 million, and the number of wires to drive each LED will also be enormous.

[0004] Incidentally, when driving each micro LED using a passive matrix method (see, for example, Patent Document 1), each LED does not continue to emit light while displaying each frame, but emits light temporarily during the scanning period, so that the drive current If needs to be increased to ensure sufficient brightness. For example, in the LED substrate disclosed in Patent Document 1, a common anode wiring a extending from an anode driver is connected to each anode of a plurality of LEDs arranged in a row direction, and the drive current If is supplied to each LED in the row direction through this anode wiring a. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-182613 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in the LED substrate disclosed in the above-mentioned Patent Document 1, if the drive current If flowing through the anode wiring a commonly connected to multiple LEDs arranged in a row in the row direction is increased, a voltage drop occurs due to the wiring impedance, and the drive voltage Vf of each LED decreases. For this reason, it is necessary to reduce the wiring impedance of the anode wiring a, but simply expanding the width of the anode wiring a causes a problem in that, in the case of a transparent display, this wiring stands out as a single line.

[0007] The present invention has been created in consideration of these points, and its object is to provide a transparent display that reduces the drop in drive voltage when the drive current is increased and prevents the wiring that carries the drive current from becoming noticeable. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the transparent display of the present invention comprises a substrate formed of a transparent material and having a plurality of partitioned pixel regions, a plurality of micro LEDs arranged in each of the plurality of pixel regions and emitting light of a respective one of a plurality of colors, wiring that applies a common driving voltage to each of the plurality of micro LEDs included in pixel regions aligned in one direction among the plurality of pixel regions, and a driver that generates the common driving voltage and applies it to the wiring, and the wiring has a plurality of branch wirings that apply the common driving voltage separately to the plurality of micro LEDs included in the same pixel region.

[0009] Instead of supplying drive current to each micro LED through a single wiring, the drive current is distributed to each micro LED through multiple branch wirings, which reduces the impedance of the multiple branch wirings as a whole and reduces the drop in drive voltage caused by the voltage drop in the wiring when the drive current is increased. In addition, since there is no need to make each branch wiring thick, it is possible to prevent the wiring from being noticeable in a transparent display.

[0010] It is also desirable that the above-mentioned multiple branched wirings are connected to the driver via a single wiring, which makes it possible to use the same driver as in the past.

[0011] In addition, the above-mentioned multiple micro LEDs are three micro LEDs that emit RGB light, and it is desirable that the micro LEDs of the same color included in the pixel area aligned in one direction are connected to the same branch wiring. This allows for regular branch wiring and the arrangement of each micro LED, making the design easier.

[0012] In addition, it is preferable that the above-mentioned multiple branch wirings are connected to each other via a connection wiring within the pixel region, so that when there is a variation in the drive current flowing through each branch wiring, it is possible to adjust the variation and further reduce the overall impedance of the combined branch wirings. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a configuration of a transparent display according to an embodiment. [Diagram 2] FIG. 1 shows a portion of a substrate including micro LEDs and wiring in each pixel area. [Diagram 3] FIG. 4 is a timing diagram of a cathode voltage applied to each cathode wiring. [Figure 4] FIG. 1 shows a portion of a substrate of a conventional transparent display. [Diagram 5] FIG. 13 is a diagram showing a portion of a substrate of a modified transparent display. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, a transparent display according to an embodiment of the present invention will be described with reference to the drawings.

[0015] Fig. 1 is a diagram showing the configuration of a transparent display according to an embodiment. The transparent display 100 shown in Fig. 1 includes a substrate 10 having a plurality of micro LEDs arranged on its surface, a cathode driver 20 that generates a driving voltage to be applied to the cathode of each micro LED, and an anode driver 30 that generates a driving voltage to be applied to the anode of each micro LED.

[0016] The substrate 10 is made of a transparent glass material or a resin material, and has a plurality of micro LEDs and a cathode wiring and an anode wiring for applying a driving voltage to each micro LED arranged on its surface. The substrate 10 also has a plurality of pixel regions 10a partitioned on its surface. These pixel regions 10a correspond to the resolution of the transparent display 100, and each pixel region 10a corresponds to one pixel. Each pixel region 10a also includes three micro LEDs that emit light corresponding to each of a plurality of colors (specifically, three colors).

[0017] The cathode driver 20 generates a cathode voltage to be applied to the cathode of each micro LED via a cathode wiring, and the anode driver 30 generates an anode voltage to be applied to the anode of each micro LED via an anode wiring.

[0018] Fig. 2 is a diagram showing a part of the substrate 10 including the micro LEDs and wiring in each pixel region 10a. As shown in Fig. 2, the substrate 10 has pixel regions 10a as pixels, and each pixel region 10a includes three micro LEDs 12r, 12g, and 12b that emit light of R (red), G (green), and B (blue), respectively. The size of these micro LEDs 12r, 12g, and 12b is smaller than the pixel region 10a of the substrate 10, so the background can be seen through the transparent pixel region 10a.

[0019] Each of the three micro LEDs 12r, 12g, and 12b in each pixel region 10 is connected to a cathode wiring 14r, 14g, and 14b as a plurality of branch wirings that separately apply the same driving voltage. These three cathode wirings 14r, 14g, and 14b extend along the scanning direction (horizontal direction in FIG. 1) of the transparent display 100 so as to pass through each pixel region 10a aligned in this scanning direction, and are connected in the same manner as each of the three micro LEDs 12r, 12g, and 12b in each pixel region 10a. That is, one cathode wiring 14r extending in the scanning direction is connected to the cathode of the micro LED 12r in each pixel region 10a. Also, one cathode wiring 14g extending in the scanning direction is connected to the cathode of the micro LED 12g in each pixel region 10a. One cathode wiring 14g extending in the scanning direction is connected to the cathode of the micro LED 12g in each pixel region 10a.

[0020] Furthermore, these three cathode wirings 14r, 14g, and 14b are connected outside the pixel region 10a on the side of the cathode driver 20. Therefore, a cathode voltage having a common voltage is applied from the cathode driver 20 through these three cathode wirings 14r, 14g, and 14b branched from one wiring to the cathodes of all the micro LEDs 12r, 12g, and 12b in all the pixel regions 10a aligned along the scanning direction.

[0021] In addition, separate anode wirings 16r, 16g, and 16b extending from the anode driver 30 are connected to the anodes of the micro LEDs 12r, 12g, and 12b, and anode voltages indicating the grayscale of each pixel corresponding to the display data are applied separately.

[0022] 3 is a timing diagram of the cathode voltage applied to each cathode wiring. The transparent display 100 of this embodiment is driven by a passive matrix method, has 128 scanning lines (vertical pixels), and generates 128 cathode voltages COM0 to COM127, each of which is effective at a different timing within one frame, by the cathode driver 20.

[0023] The cathode voltage COM0 is applied to the cathodes of the micro LEDs 12r, 12g, and 12b included in the pixel regions 10a arranged along the scanning line (L0) at the top of the substrate 10, and the voltage level temporarily changes from H to L in accordance with the scanning timing of the scanning line L0. This cathode voltage is simultaneously applied to the cathodes of all the micro LEDs 12r, 12g, and 12b included in the scanning line L0 via the three cathode wirings 14r, 14g, and 14b whose ends are connected. In parallel with the application of this cathode voltage, an anode voltage indicating the grayscale of each pixel corresponding to the display data is applied to the anodes of the micro LEDs 12r, 12g, and 12b from the anode driver 30 via the anode wirings 16r, 16g, and 16b.

[0024] Similarly, the cathode voltage COM1 is applied to the cathodes of the micro LEDs 12r, 12g, and 12b included in the pixel regions 10a arranged along the second scanning line (L1) from the top of the substrate 10, and the voltage level temporarily changes from H to L in accordance with the scanning timing of the scanning line L1. This cathode voltage is simultaneously applied to the cathodes of all the micro LEDs 12r, 12g, and 12b included in the scanning line L0 via the three cathode wirings 14r, 14g, and 14b whose ends are connected. In parallel with the application of this cathode voltage, the anode driver 30 applies an anode voltage indicating the grayscale of each pixel corresponding to the display data to the anodes of the micro LEDs 12r, 12g, and 12b via the anode wirings 16r, 16g, and 16b. The same applies to the other scan lines, and cathode voltages COM2 to COM127 with shifted scan timing are simultaneously applied from the cathode driver 20 to the cathodes of all the micro LEDs 12r, 12g, and 12b included in each scan line via the cathode wirings 14r, 14g, and 14b.

[0025] FIG. 4 is a diagram showing a part of a substrate of a conventional transparent display, and the same part is shown for comparison with FIG. 2. As shown in FIG. 4, conventionally, the cathodes of three micro LEDs 12r, 12g, and 12g in the same pixel region 10a are connected to a common cathode wiring 14c (anode wiring extending in the scanning direction in Patent Document 1), and a cathode voltage is applied to these three micro LEDs 12r, 12g, and 12g at the same time at the same timing. Therefore, a wide cathode wiring 14c is required to increase the drive current to increase the brightness of each pixel. However, in this embodiment, separate cathode wirings 14r, 14b, and 14b are connected to the cathodes of the three micro LEDs 12r, 12g, and 12b in the same pixel region 10a and a cathode voltage is applied, so that it is possible to narrow the width of each cathode wiring 14r, 14b, and 14b while maintaining the total drive current of the three micro LEDs 12r, 12g, and 12b.

[0026] In this way, in the transparent display 100 of the present embodiment, the driving current is not supplied to each micro LED 12r, 12g, 12b through one wiring, but is distributed to each micro LED 12r, 12g, 12b through the cathode wiring 14r, 14g, 14b as a plurality of branch wirings, so that the impedance of the plurality of cathode wirings 14r, 14g, 14b as a whole can be reduced, and the drop in driving voltage caused by the voltage drop of the wiring when the driving current is increased can be reduced. In addition, since it is not necessary to make each of the cathode wirings 14r, 14g, 14b thick, it is possible to prevent the wiring from being noticeable in the transparent display 100.

[0027] In addition, since the ends of the three cathode wirings 14r, 14g, and 14b are wired together and connected to the cathode driver 20, it is possible to use the same cathode driver 20 as in the conventional case where one cathode wiring 14c (Figure 4) is used.

[0028] In addition, three micro LEDs 12r, 12g, and 12b emitting each of RGB light are used, and micro LEDs of the same color included in the pixel region 10a aligned in one direction are connected to the same cathode wiring 14r, 14g, and 14b. This makes it possible to regularly arrange the cathode wiring 14r, 14g, and 14b and the micro LEDs 12r, 12g, and 12b, making design easier.

[0029] Fig. 5 is a diagram showing a part of a substrate of a transparent display according to a modified example. The configuration shown in Fig. 5 differs from the configuration shown in Fig. 2 in that a connection wiring 14m is added to connect three cathode wirings 14r, 14g, and 14b passing through each pixel region 10a to each other.

[0030] Although a driving current flows simultaneously through the three micro LEDs 12r, 12g, and 12b in the same pixel region 10a, the value is not the same depending on the brightness of each of the R, G, and B colors. Therefore, when the driving current flows through the separate cathode wirings 14r, 14g, and 14b, strictly speaking, there is some variation in the voltage drop in each of the cathode wirings 14r, 14g, and 14b. However, by adding the connection wiring 14m shown in Figure 5, this variation can be eliminated, and the overall impedance of the cathode wirings 14r, 14g, and 14b can be further reduced.

[0031] The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention. In the above embodiment, the cathode wirings 14r, 14g, and 14b extend in the scanning direction, but the present invention can also be applied to the case where the anode wirings extend in the scanning direction, as in Patent Document 1.

[0032] In addition, in the above-described embodiment, it is assumed that one cathode wiring is distributed into three cathode wirings 14r, 14g, and 14b for the three micro LEDs 12r, 12g, and 12b arranged horizontally in the pixel region 10a as shown in FIG. 4. However, since separating the three cathode wirings 14r, 14g, and 14b increases the freedom of arrangement of the three micro LEDs 12r, 12g, and 12b in the pixel region 10a, the three micro LEDs 12r, 12g, and 12b may be arranged vertically or another arrangement may be adopted. [Industrial Applicability]

[0033] As described above, according to the present invention, instead of supplying a driving current to each micro LED through one wiring, the driving current is distributed to each micro LED through multiple branch wirings, so that the impedance of the multiple branch wirings as a whole can be reduced, and the drop in driving voltage caused by the voltage drop of the wiring when the driving current is increased can be reduced. In addition, since there is no need to make each branch wiring thick, it is possible to prevent the wiring from being noticeable in the transparent display. [Explanation of symbols]

[0034] 100 Transparent Display 10 Substrate 10a Pixel area 12r, 12g, 12b Micro LED 14c, 14r, 14g, 14b cathode wiring 14m connection cable 16r, 16g, 16b anode wiring 20 Cathode Driver 30 Anode Driver

Claims

1. A substrate formed of a transparent material and having a plurality of partitioned pixel regions; A plurality of micro LEDs are disposed in each of the plurality of pixel regions, the micro LEDs emitting light of a plurality of colors respectively; Wiring that applies a common driving voltage to each of the plurality of micro LEDs included in pixel regions aligned in one direction among the plurality of pixel regions; a driver that generates the common driving voltage and applies it to the wiring; wherein the wiring has a plurality of branched wirings that separately apply the common driving voltage to the plurality of micro LEDs included in the same pixel region.

2. The transparent display according to claim 1 , wherein the plurality of branched wirings are connected to the driver via a single wiring.

3. The plurality of micro LEDs are three micro LEDs each emitting RGB light, The transparent display according to claim 1 , wherein the micro-LEDs of the same color included in the pixel regions aligned in one direction are connected to the same branch wiring.

4. 2. The transparent display according to claim 1, wherein the plurality of branch wirings are connected to each other via connection wiring within the pixel region.

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