A pixel unit of an LED display

Abstract

A pixel unit of an LED display includes a backboard, a single light emitting diode arranged on the backboard, a collimating lens arranged in a light path of the light emitting diode for collimating a light beam of the light emitting diode to form a collimated light beam, and a waveguide arranged in the light path of the collimated light beam. The waveguide includes a wavelength selection unit and a coupling-out unit arranged adjacently. The pixel unit of the LED display is provided, so that only one LED chip is arranged on the corresponding backboard of the pixel unit, and the work load of micro-LED display mass transfer and the complexity of display circuit arrangement are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of LED displays, and in particular relates to a pixel unit of an LED display. Background Art

[0002] Micro LED technology, or LED miniaturization and matrix technology, refers to a high-density, tiny LED array integrated on a single chip. Like an LED display, each pixel can be addressed and individually driven. This can be considered a miniature version of an outdoor LED display, reducing the pixel spacing from millimeters to microns.

[0003] The Micro LED display uses the normal CMOS integrated circuit manufacturing process to make the LED display driver circuit at the bottom layer, and then uses an MOCVD machine to make the LED array on the integrated circuit, thus realizing a micro display, which is also known as a smaller version of the LED display.

[0004] Micro LED has the characteristics of high efficiency, high brightness, high reliability and fast response time. It is also self-luminous and does not require a backlight. It has the advantages of energy saving, simple structure, small size and thinness.

[0005] like Figure 1 As shown, the existing Micro LED display includes multiple pixel units, each of which contains RGB three-color light-emitting units. There are two cases of the cross-sectional diagram of the pixel unit: 1. Directly installing the RGB three-color LED chip on the backplane (such as Figure 2 ); 2. In order to save costs, three low-cost blue (B) LEDs are installed on the back panel, and a wavelength conversion layer 120 (usually a color filter material, etc.) is installed in the light emitting direction of the LED so that the pixel unit can emit RGB three colors (such as Figure 3 ).

[0006] Regardless of which of the above methods is used, three LED chips need to be installed on the backplane, which makes the workload of mass transfer of micro-led displays very huge and the display circuit layout complex. Summary of the Invention

[0007] To solve the above problems, the present invention provides a pixel unit for an LED display, so that only one LED chip needs to be installed on the backplane corresponding to the pixel unit, greatly reducing the workload of mass transfer of micro-LED displays and the complexity of display circuit layout.

[0008] A technical solution adopted in the present invention is:

[0009] A pixel unit of an LED display, comprising:

[0010] a back panel, and a single light-emitting diode disposed on the back panel;

[0011] A collimating lens, which is arranged on the light output path of the light emitting diode and is used to collimate the light beam output by the light emitting diode to form a collimated light beam;

[0012] a waveguide, the waveguide being arranged on an optical path of the collimated light beam;

[0013] The waveguide includes: a wavelength selection unit and a coupling unit arranged adjacent to each other,

[0014] The wavelength selection unit is provided at the light beam entrance of the waveguide, and is used to couple part or all of the light beam of a specific wavelength into the waveguide for total reflection transmission, and transmit the remaining light beam out of the waveguide;

[0015] The outcoupling unit is used to couple part or all of the light beam transmitted by total reflection in the waveguide out of the waveguide.

[0016] Preferably, the light emitting diode is a white light emitting LED.

[0017] Preferably, the adjacently arranged wavelength selection units include a first wavelength selection unit and a second wavelength selection unit, the first wavelength selection unit is used to couple part / all of the first wavelength light beam into the waveguide, and the second wavelength selection unit is used to couple part / all of the second wavelength light beam into the waveguide.

[0018] Preferably, the outcoupling unit includes a first outcoupling unit arranged corresponding to the first wavelength selection unit and a second outcoupling unit arranged corresponding to the second wavelength selection unit, the first outcoupling unit being used to export part / all of the first wavelength light beam transmitted by total reflection in the waveguide out of the waveguide; the second outcoupling unit being used to export part / all of the second wavelength light beam transmitted by total reflection in the waveguide out of the waveguide.

[0019] Preferably, the first wavelength selection unit is used to guide part / all of the first wavelength light beam into the waveguide for total reflection transmission along a first direction, and transmit the remaining light beam; the second wavelength selection unit is used to guide part / all of the second wavelength light beam into the waveguide for total reflection transmission along a second direction, and transmit the remaining light beam; the first direction is opposite to the second direction.

[0020] Preferably, the first outcoupling unit is located on one side of the first wavelength selection unit along the first direction, and is used to export part / all of the first wavelength light beam transmitted by total reflection in the waveguide out of the waveguide; the second outcoupling unit is located on one side of the second wavelength selection unit along the second direction, and is used to export part / all of the second wavelength light beam transmitted by total reflection in the waveguide out of the waveguide.

[0021] Preferably, the first wavelength selection unit and the second wavelength selection unit are arranged at the center of the waveguide, so that the collimated light beam enters the first wavelength selection unit and the second wavelength selection unit.

[0022] Preferably, it further includes a transmittance controller, which is arranged on the optical path transmitted through the waveguide and is used to control the transmittance of a specific wavelength through an electrical signal, thereby adjusting the brightness of the light beam in the pixel unit.

[0023] Preferably, it further comprises a scattering layer, which is arranged on the transmittance controller and / or the outcoupling unit and is used for scattering the light beam.

[0024] Preferably, the scattering layer comprises an adhesive and light-scattering particles distributed in the adhesive.

[0025] Preferably, the wavelength selection unit is a dichroic film layer or a grating.

[0026] Preferably, the outcoupling unit is a dichroic film layer or a grating.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention replaces the original technology that requires three LED chips with a single LED chip, which not only reduces the workload of mass transfer of micro-LED displays, but also reduces the complexity of circuit layout.

[0029] 2. The present invention uses a single LED chip to replace the original technology that requires three LED chips, which not only saves LED chips and reduces the cost, but also reduces the heat generation due to the reduction in the number of LED chips, and also reduces the heat dissipation load of the display screen. Compared with traditional technologies, it is more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural diagram of an LED display in the prior art.

[0031] Figure 2 This is a schematic diagram of a pixel unit structure in the prior art.

[0032] Figure 3 FIG. 1 is a structural diagram of another pixel unit in the prior art.

[0033] Figure 4 A schematic structural diagram of a pixel unit of an LED display provided in an embodiment of the present application.

[0034] Figure 5 A schematic structural diagram of a pixel unit of another LED display provided in an embodiment of the present application.

[0035] The text labels in the figure are as follows: 100, display; 110, pixel unit; 120, wavelength conversion layer; 1, backplane; 2, LED; 3, collimating lens; 4, waveguide; 5, transmittance controller; 6, scattering layer; 41, first wavelength selection unit; 42, first coupling unit; 43, second wavelength selection unit; 44, second coupling unit. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0037] Example 1:

[0038] like Figure 4 As shown, a back plate 1 and a single light emitting diode arranged on the back plate 1. In this embodiment, the single light emitting diode is a single LED 2 that emits white light, wherein the white light includes light beams of red, green and blue color bands.

[0039] Collimating lens 3 is disposed on the light-emitting diode's light-emitting path and is used to collimate the light beam emitted by light-emitting diode 2, forming a collimated beam. In this embodiment, collimating lens 3 is disposed on the light-emitting path of LED 2, which emits white light. Since the light beam emitted by the LED is divergent light, collimating lens 3 is used to collimate the light beam emitted by LED 2, forming a collimated beam.

[0040] The waveguide 4 is arranged on the optical path of the collimated light beam. In this embodiment, the optical path of the collimated light beam is opposite the center of the waveguide 4. The first wavelength selection unit 41 and the second wavelength selection unit 43 are adjacently arranged at the light entrance at the center of the waveguide 4, and the first coupling unit 42 is arranged corresponding to the first wavelength selection unit 41; and the second coupling unit 44 is arranged corresponding to the second wavelength selection unit 43.

[0041] The first wavelength selection unit 41 is used to couple the red light beam into the waveguide 4, so that it satisfies the total reflection condition and is transmitted along the X direction by total reflection until it enters the first decoupling unit 42, and then couples the transmitted light beam in the waveguide 4 out of the waveguide 4; the remaining light beams not coupled into the waveguide 4 by the first wavelength selection unit 41 are transmitted into the transmittance controller 5. In this embodiment, the remaining light beams are the blue light beam B and the green light beam G.

[0042] The second wavelength selection unit 43 is used to couple the green light beam into the waveguide 4, so that it satisfies the total reflection condition and is transmitted along the -X direction by total reflection until it enters the second decoupling unit 44, and then couples the transmitted light beam in the waveguide 4 out of the waveguide 4; the remaining light beams not coupled into the waveguide 4 by the second wavelength selection unit 43 are transmitted into the transmittance controller 5. In this embodiment, the remaining light beams are the blue light beam B and the red light beam R.

[0043] A transmittance controller 5 is provided on the light output path of the remaining light beams not coupled into the waveguide 4 by the first wavelength selection unit 41 and the remaining light beams not coupled into the waveguide 4 by the second wavelength selection unit 43. In this embodiment, the transmittance controller 5 is an electrically controlled liquid crystal layer, that is, the transmittance of the blue light is controlled by an electrical signal, thereby screening out the blue light beam B and adjusting the brightness of the blue light in the pixel unit 110.

[0044] The brightness of the red light beam R is modulated by the first wavelength selection unit 41 or the first outcoupling unit 42. The first wavelength selection unit 41 may be a dichroic film or a grating. In this embodiment, the dichroic film can reflect and direct the red light beam into the waveguide 4, while the grating can diffract and direct the red light beam into the waveguide 4. When the first wavelength selection unit 41 has a modulation function, it may be an electro-dichroic film, which electrically controls the ratio of the red light beam reflected and directed into the waveguide 4. Alternatively, the first wavelength selection unit 41 may be a cholesteric liquid crystal grating, which electrically controls the ratio of the red light beam diffracted and directed into the waveguide 4, thereby modulating the brightness of the red light in the pixel unit 110.

[0045] The first outcoupling unit 42 is a dichroic film layer or a grating. In this embodiment, the dichroic film layer can reflect the red band light beam out of the waveguide 4, and the grating can diffract the red band light beam out of the waveguide 4. When the first outcoupling unit 42 has a modulation function, the first outcoupling unit 42 can be an electro-dichroic film layer, that is, the ratio of the red band light beam reflected out of the waveguide 4 is electrically controlled to adjust; or the first outcoupling unit 42 can be a cholesteric liquid crystal grating, that is, the ratio of the red band light beam diffracted out of the waveguide 4 is electrically controlled to adjust, thereby modulating the brightness of the red light in the pixel unit 110.

[0046] The brightness of the green light beam G is modulated by the second wavelength selection unit 43 or the second outcoupling unit 44. The second wavelength selection unit 43 may be a dichroic film or a grating. In this embodiment, the dichroic film can reflect and direct the green light beam into the waveguide 4, while the grating can diffract and direct the green light beam into the waveguide 4. When the second wavelength selection unit 43 has a modulation function, it may be an electro-dichroic film, which electrically controls the ratio of the green light beam reflected and directed into the waveguide 4. Alternatively, the second wavelength selection unit 43 may be a cholesteric liquid crystal grating, which electrically controls the ratio of the green light beam diffracted and directed into the waveguide 4, thereby modulating the brightness of the green light in the pixel unit 110.

[0047] The second outcoupling unit 44 may be a dichroic film layer or a grating. In this embodiment, the dichroic film layer reflects the green-band light beam to the waveguide 4, and the grating diffracts the green-band light beam to the waveguide 4. When the second outcoupling unit 44 has a modulation function, the second outcoupling unit 44 may be an electro-dichroic film layer, that is, the ratio of the green-band light beam reflected to the waveguide 4 is electrically controlled to be adjusted, or the second outcoupling unit 44 may be a cholesteric liquid crystal grating, that is, the ratio of the green-band light beam diffracted to the waveguide 4 is electrically controlled to be adjusted, thereby modulating the brightness of the green light in the pixel unit 110.

[0048] The dichroic film layer in the manual is also called a dichroic mirror, which has the characteristics of almost completely transmitting light of a certain wavelength and almost completely reflecting light of other wavelengths.

[0049] The cholesteric liquid crystal described in this specification is a cholesterol derivative that exhibits a liquid crystal phase within a certain temperature range. Its molecules contain chiral carbon atoms and a periodic helical structure. When an external electric field of varying intensities is applied, the helical structure of the cholesteric molecules changes, resulting in light beam reflection or absorption. Therefore, cholesteric liquid crystal gratings can reflect light of different wavelengths as needed by adding optical rotators of different helical pitches, without the need for color filters.

[0050] Example 2:

[0051] like Figure 5 As shown, a back panel 1 and a single light emitting diode arranged on the back panel. In this embodiment, the single light emitting diode is a single LED 2 that emits white light, wherein the white light includes beams of red, green and blue wavelength bands.

[0052] Collimating lens 3 is disposed on the light-emitting diode's light-emitting path and is used to collimate the light beam emitted by the light-emitting diode to form a collimated beam. In this embodiment, collimating lens 3 is disposed on the light-emitting path of LED 2, which emits white light. Since the light beam emitted by the LED is divergent light, collimating lens 3 is used to collimate the light beam emitted by LED 2 to form a collimated beam.

[0053] The waveguide 4 is arranged on the optical path of the collimated light beam. In this embodiment, the optical path of the collimated light beam is opposite the center of the waveguide 4. The first wavelength selection unit 41 and the second wavelength selection unit 43 are adjacently arranged at the light entrance at the center of the waveguide 4, and the first coupling unit 42 is arranged corresponding to the first wavelength selection unit 41; and the second coupling unit 44 is arranged corresponding to the second wavelength selection unit 43.

[0054] The first wavelength selection unit 41 is used to couple the red light beam into the waveguide 4, so that it satisfies the total reflection condition and is transmitted along the X direction by total reflection until it enters the first decoupling unit 42, and then couples the transmitted light beam in the waveguide 4 out of the waveguide 4; the remaining light beams not coupled into the waveguide 4 by the first wavelength selection unit 41 are transmitted into the transmittance controller 5. In this embodiment, the remaining light beams are the blue light beam B and the green light beam G.

[0055] The second wavelength selection unit 43 is used to couple the green light beam into the waveguide 4, so that it satisfies the total reflection condition and is transmitted along the -X direction by total reflection until it enters the second decoupling unit 44, and then couples the transmitted light beam in the waveguide 4 out of the waveguide 4; the remaining light beams not coupled into the waveguide 4 by the second wavelength selection unit 43 are transmitted into the transmittance controller 5. In this embodiment, the remaining light beams are the blue light beam B and the red light beam R.

[0056] A transmittance controller 5 is provided on the light output path of the remaining light beams not coupled into the waveguide 4 by the first wavelength selection unit 41 and the remaining light beams not coupled into the waveguide 4 by the second wavelength selection unit 43. In this embodiment, the transmittance controller 5 is an electrically controlled liquid crystal layer, that is, the transmittance of the blue light is controlled by an electrical signal, thereby screening out the blue light beam B and adjusting the brightness of the blue light in the pixel unit 110.

[0057] A scattering layer 6 is provided on the outgoing light path of the transmittance controller 5, the first outcoupling unit 42, and the second outcoupling unit 44 to scatter the light beams. Because the outgoing light beams from the transmittance controller 5, the first outcoupling unit 42, and the second outcoupling unit 44 are collimated, which is detrimental to the display quality of the display 100, the scattering layer is provided to scatter the light beams and expand the visible area.

[0058] The scattering layer 6 includes an adhesive and particles distributed in the adhesive for light dispersion. The size of the particles can range from tens of nanometers to several microns. The adhesive can include a transparent material such as acrylic, polyurethane, or epoxy resin. The particles can be transparent organic particles or inorganic particles. The organic particles can include multi-layered multi-component particles formed by forming a particle layer and covering the particle layer with another type of monomer. The particle layer includes at least one of acrylic particles, olefin particles, and copolymers and homopolymers of acrylic and olefin particles. The acrylic particles can be methyl methacrylate or 2-ethylhexyl acrylate, and the olefin particles can be polyethylene. The inorganic particles can include at least one selected from silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, and magnesium fluoride.

[0059] The brightness of the red light beam R is modulated by the first wavelength selection unit 41 or the first outcoupling unit 42. The first wavelength selection unit 41 may be a dichroic film or a grating. In this embodiment, the dichroic film can reflect and direct the red light beam into the waveguide 4, while the grating can diffract and direct the red light beam into the waveguide 4. When the first wavelength selection unit 41 has a modulation function, it may be an electro-dichroic film, which electrically controls the ratio of the red light beam reflected and directed into the waveguide 4. Alternatively, the first wavelength selection unit 41 may be a cholesteric liquid crystal grating, which electrically controls the ratio of the red light beam diffracted and directed into the waveguide 4, thereby modulating the brightness of the red light in the pixel unit 110.

[0060] The first outcoupling unit 42 is a dichroic film layer or a grating. In this embodiment, the dichroic film layer can reflect the red band light beam out of the waveguide 4, and the grating can diffract the red band light beam out of the waveguide 4. When the first outcoupling unit 42 has a modulation function, the first outcoupling unit 42 can be an electro-dichroic film layer, that is, the ratio of the red band light beam reflected out of the waveguide 4 is electrically controlled to adjust; or the first outcoupling unit 42 can be a cholesteric liquid crystal grating, that is, the ratio of the red band light beam diffracted out of the waveguide 4 is electrically controlled to adjust, thereby modulating the brightness of the red light in the pixel unit 110.

[0061] The brightness of the green light beam G is modulated by the second wavelength selection unit 43 or the second outcoupling unit 44. The second wavelength selection unit 43 may be a dichroic film or a grating. In this embodiment, the dichroic film can reflect and direct the green light beam into the waveguide 4, while the grating can diffract and direct the green light beam into the waveguide 4. When the second wavelength selection unit 43 has a modulation function, it may be an electro-dichroic film, which electrically controls the ratio of the green light beam reflected and directed into the waveguide 4. Alternatively, the second wavelength selection unit 43 may be a cholesteric liquid crystal grating, which electrically controls the ratio of the green light beam diffracted and directed into the waveguide 4, thereby modulating the brightness of the green light in the pixel unit 110.

[0062] The second outcoupling unit 44 may be a dichroic film layer or a grating. In this embodiment, the dichroic film layer reflects the green-band light beam to the waveguide 4, and the grating diffracts the green-band light beam to the waveguide 4. When the second outcoupling unit 44 has a modulation function, the second outcoupling unit 44 may be an electro-dichroic film layer, that is, the ratio of the green-band light beam reflected to the waveguide 4 is electrically controlled to be adjusted, or the second outcoupling unit 44 may be a cholesteric liquid crystal grating, that is, the ratio of the green-band light beam diffracted to the waveguide 4 is electrically controlled to be adjusted, thereby modulating the brightness of the green light in the pixel unit 110.

[0063] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0064] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method of the present invention and its core ideas. The above is only a preferred implementation method of the present invention. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of the present invention.

Claims

1. A pixel unit of an LED display, characterized in that: include: A back panel, and a single light emitting diode disposed on the back panel, wherein the light emitting diode is a white light emitting LED; A collimating lens, which is arranged on the light output path of the light emitting diode and is used to collimate the light beam output by the light emitting diode to form a collimated light beam; A waveguide, wherein the waveguide is arranged on the optical path of the collimated light beam, the optical path of the collimated light beam is directly opposite the center of the waveguide, and the waveguide includes a wavelength selection unit and a coupling unit arranged adjacent to each other, The wavelength selection unit is arranged at the light beam entrance of the waveguide, and is used to couple part / all of the light beam of a specific wavelength into the waveguide for total reflection transmission, and transmit the rest of the light beam out of the waveguide; the adjacent wavelength selection units include a first wavelength selection unit and a second wavelength selection unit, and the first wavelength selection unit and the second wavelength selection unit are arranged at the center of the waveguide; the first wavelength selection unit is used to couple part / all of the first wavelength light beam into the waveguide, and the second wavelength selection unit is used to couple part / all of the second wavelength light beam into the waveguide; the first wavelength selection unit is used to introduce part / all of the first wavelength light beam into the waveguide along a first direction for total reflection transmission, and transmit the rest of the light beam; the second wavelength selection unit is used to introduce part / all of the second wavelength light beam into the waveguide along a second direction for total reflection transmission, and transmit the rest of the light beam; the first direction is opposite to the second direction; It also includes a transmittance controller, which is arranged on the optical path transmitted through the waveguide, and the transmittance controller is an electrically controlled liquid crystal layer for controlling the transmittance of blue light; The outcoupling unit is used to couple part or all of the light beam transmitted by total reflection in the waveguide out of the waveguide.

2. A pixel unit of an LED display according to claim 1, characterized in that: The outcoupling unit includes a first outcoupling unit arranged corresponding to the first wavelength selection unit and a second outcoupling unit arranged corresponding to the second wavelength selection unit; the first outcoupling unit is used to export part / all of the first wavelength light beam transmitted by total reflection in the waveguide out of the waveguide, and the second outcoupling unit is used to export part / all of the second wavelength light beam transmitted by total reflection in the waveguide out of the waveguide.

3. The pixel unit of an LED display according to claim 2, characterized in that: The first outcoupling unit is located on one side of the first wavelength selection unit along the first direction, and is used to export part / all of the first wavelength light beam transmitted by total reflection in the waveguide out of the waveguide; the second outcoupling unit is located on one side of the second wavelength selection unit along the second direction, and is used to export part / all of the second wavelength light beam transmitted by total reflection in the waveguide out of the waveguide.

4. A pixel unit of an LED display according to any one of claims 1 to 3, characterized in that: It also includes a scattering layer, which is arranged on the transmittance controller and / or the outcoupling unit and is used to scatter the light beam.

5. The pixel unit of an LED display according to claim 4, characterized in that: The scattering layer includes a binder and light-scattering particles distributed in the binder.

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