Backlight unit and display device

Abstract

Embodiments of this disclosure relate to backlight units and display devices. A backlight unit may be provided in which an optical plate comprising an engraved pattern in which a color conversion material is disposed is positioned on a light source. Because the color conversion material is disposed within the engraved pattern, changes in the color conversion material caused by external factors can be prevented, and the amount of color conversion material can be reduced. Therefore, a backlight unit that provides image quality greater than or equal to a certain level and whose reliability is improved can be easily realized.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0091865, filed on July 13, 2021, which is incorporated herein by reference for all purposes, as fully set forth herein. Technical Field

[0003] Embodiments of this disclosure relate to backlight units and display devices. Background Technology

[0004] The development of the information society has led to an increased demand for display devices used to display images, as well as for various types of display devices (e.g., liquid crystal displays, organic light-emitting displays, etc.).

[0005] A liquid crystal display device may include a display panel and a light source device, such as a backlight unit, that provides light to the display panel.

[0006] The display panel can display images by controlling the degree to which light supplied from the backlight unit is transmitted.

[0007] Since the quality of the image displayed by the display panel may vary depending on the quality of the image represented by the backlight unit, there is a need for methods that can improve the image quality and reliability of the backlight unit. Summary of the Invention

[0008] Embodiments of this disclosure may provide a backlight unit that improves image quality and reliability, and a display device including the backlight unit.

[0009] Embodiments of this disclosure may provide a backlight unit that exhibits a certain level of image quality and has a reduced overall thickness, as well as a display device including the backlight unit.

[0010] Embodiments of this disclosure may provide a backlight unit comprising: a plurality of light sources on a substrate; a reflector on the substrate, the reflector including a plurality of holes, wherein at least some of the holes are configured to accommodate each of the plurality of light sources; and an optical plate positioned on the plurality of light sources and the reflector, wherein the optical plate includes a plurality of engraved patterns on a bottom surface corresponding to each of the plurality of light sources and a color conversion portion comprising a color conversion material disposed within the plurality of engraved patterns.

[0011] Embodiments of this disclosure may provide a backlight unit, comprising: a plurality of light sources on a substrate; a reflector on the substrate disposed on at least a portion of a region not overlapping with the plurality of light sources; and an optical plate positioned on the reflector, wherein the optical plate includes a plurality of first engraved patterns corresponding to each of the plurality of light sources, and at least one second engraved pattern not corresponding to the plurality of light sources, wherein a color conversion portion including a color conversion material is disposed within the plurality of first engraved patterns and at least one second engraved pattern.

[0012] Embodiments of this disclosure may provide a display device including the aforementioned backlight unit and a display panel that supplies light from the backlight unit.

[0013] According to various embodiments of the present disclosure, a backlight unit that maintains image quality and improves its reliability can be provided, as well as a display device including the backlight unit.

[0014] According to various embodiments of the present disclosure, a backlight unit that improves image quality and reduces its overall thickness can be provided, as well as a display device including the backlight unit. Attached Figure Description

[0015] The above and other objects, features and advantages of this disclosure will become more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 This is a diagram schematically illustrating the configuration included in a display device according to an embodiment of the present disclosure;

[0017] Figure 2 This is a cross-sectional view of an example of a backlight unit according to an embodiment of the present disclosure;

[0018] Figure 3 Is included Figure 2 Plan view and cross-sectional view of an example optical plate in the backlight unit shown;

[0019] Figure 4A and Figure 4B It shows the manufacturing process. Figure 3 A diagram illustrating an example of the method using an optical plate;

[0020] Figures 5 to 7 It is a cross-sectional view of a backlight unit including another example of an optical plate according to an embodiment of the present disclosure; and

[0021] Figures 8 to 12 This is a cross-sectional view of another example of a backlight unit according to an embodiment of the present disclosure. Detailed Implementation

[0022] In the following description of examples or embodiments of this disclosure, reference will be made to the accompanying drawings, in which specific examples or embodiments that may be implemented are illustrated by way of illustration, and in the drawings, the same reference numerals and symbols may be used to denote the same or similar components, even when these components are shown in different drawings. Furthermore, in the following description of examples or embodiments of this disclosure, detailed descriptions of well-known functions and components incorporated herein will be omitted where it is determined that such description may make the subject matter of some embodiments of this disclosure considerably unclear. Terms such as “comprising,” “having,” “including,” “constituting,” “made of,” and “formed from” as used herein are generally intended to allow for the addition of additional components, unless these terms are used in conjunction with the term “only.” As used herein, singular forms are intended to include plural forms unless the context clearly indicates otherwise.

[0023] In this document, terms such as “first,” “second,” “A,” “B,” “(A),” or “(B)” may be used to describe elements of this disclosure. Each of these terms is not used to define the nature, order, sequence, or number of elements, but only to distinguish the corresponding element from other elements.

[0024] When referring to a first element as "connected or coupled to," "in contact with," or "overlapping" with a second element, it should be understood that not only can the first element be "directly connected or coupled to" or "directly in contact with or overlap" with the second element, but a third element can also be "inserted" between the first and second elements, or the first and second elements can be "connected or coupled," "in contact with," or "overlapping" with each other via a fourth element. Here, a second element can be included in at least one of two or more elements that are "connected or coupled," "in contact with," or "overlapping" with each other.

[0025] When time-related terms such as “after,” “follow,” “next,” “before,” etc., are used to describe the handling or operation of an element or configuration, or a process or step in an operation, handling, or manufacturing method, these terms may be used to describe non-continuous or non-sequential handling or operation, unless the terms “directly” or “immediately after” are used together.

[0026] Furthermore, when referring to any size, relative size, etc., it should be assumed that the numerical values ​​or corresponding information (e.g., levels, ranges, etc.) of an element or feature include tolerances or error ranges that may be caused by various factors (e.g., process factors, internal or external influences, noise, etc.), even if no relevant description is specified. In addition, the term "may" fully encompasses all the meanings of the term "able to".

[0027] In the following, various embodiments of this disclosure will be described in detail with reference to the accompanying drawings.

[0028] Figure 1 This diagram schematically illustrates the configuration included in a display device 100 according to embodiments of the present disclosure. All components of the display device 100 according to all embodiments of the present disclosure are operatively coupled and configured.

[0029] Reference Figure 1 The display device 100 may include a display panel 110 and a gate driving circuit 120, a data driving circuit 130 and a controller 140 for driving the display panel 110.

[0030] The display panel 110 may include an active area AA in which multiple sub-pixels SP are provided, and a non-active area located outside the active area AA.

[0031] Multiple gate lines GL and multiple data lines DL can be arranged on the display panel 110. Multiple sub-pixels SP can be located in the area where the gate lines GL and data lines DL intersect.

[0032] The gate drive circuit 120 is controlled by the controller 140 and sequentially outputs the scan signal to multiple gate lines GL arranged on the display panel 110, thereby controlling the driving timing of multiple sub-pixels SP.

[0033] The gate drive circuit 120 may include one or more gate driver integrated circuits (GDICs), and depending on the driving method, it may be located only on one side of the display panel 110 or on both sides of the display panel 110.

[0034] Each gate driver integrated circuit (GDIC) can be connected to the bonding pads of the display panel 110 via a tape-on-brush (TAB) method or a chip-on-glass (COG) method. Each GDIC can also be implemented using an in-panel gate-in-patch (GIP) method, thus being directly disposed on the display panel 110. In some cases, the GDIC can be integrated and disposed on the display panel 110. Alternatively, each GDIC can be implemented using a chip-on-film (COF) method, in which components are mounted on a film connected to the display panel 110.

[0035] The data driving circuit 130 receives image data DATA from the controller 140 and converts the image data into an analog data voltage Vdata. Then, the data driving circuit 130 outputs the data voltage Vdata to each data line DL according to the timing of the scan signal applied through the gate line GL, so that each of the plurality of sub-pixels SP emits light with a brightness according to the image data.

[0036] The data drive circuit 130 may include one or more source driver integrated circuits (SDICs).

[0037] Each source driver integrated circuit (SDIC) may include a shift register, latch circuit, digital-to-analog converter, output buffer, etc.

[0038] Each source driver integrated circuit (SDIC) can be connected to the bonding pads of the display panel 110 via a tape-on-board (TAB) method or a chip-on-glass (COG) method. Each source driver integrated circuit (SDIC) can be directly disposed on the display panel 110. In some cases, the source driver integrated circuit (SDIC) can be integrated and disposed on the display panel 110. Alternatively, each source driver integrated circuit (SDIC) can be implemented using a chip-on-film (COF) method. In this case, each source driver integrated circuit (SDIC) can be mounted on a film connected to the display panel 110 and can be electrically connected to the display panel 110 via wires on the film.

[0039] The controller 140 supplies various control signals to the gate drive circuit 120 and the data drive circuit 130, and controls the operation of the gate drive circuit 120 and the data drive circuit 130.

[0040] The controller 140 can be mounted on a printed circuit board, flexible printed circuit, etc., and can be electrically connected to the gate drive circuit 120 and the data drive circuit 130 through the printed circuit board, flexible printed circuit, etc.

[0041] The controller 140 allows the gate drive circuit 120 to output a scan signal according to a timing implemented on a per-frame basis. The controller 140 can convert data signals received from the outside into a data signal format that conforms to the data drive circuit 130, and then output the converted image data to the data drive circuit 130.

[0042] The controller 140 receives various timing signals, including vertical synchronization signal VSYNC, horizontal synchronization signal HSYNC, input data enable signal DE, clock signal CLK, etc., and image data from an external source (e.g., a host system).

[0043] The controller 140 can generate various control signals using various timing signals received from the outside, and can output the control signals to the gate drive circuit 120 and the data drive circuit 130.

[0044] For example, in order to control the gate drive circuit 120, the controller 140 can output various gate control signals GCS, including the gate start pulse GSP, the gate shift clock GSC, the gate output enable signal GOE, etc.

[0045] The gate start pulse (GSP) controls the start timing of operation for one or more gate driver integrated circuits (GDICs) constituting the gate drive circuit 120. The gate shift clock (GSC), which is a clock signal commonly input to one or more gate driver integrated circuits (GDICs), controls the shift timing of the scan signal. The gate output enable signal (GOE) specifies timing information for one or more gate driver integrated circuits (GDICs).

[0046] In addition, in order to control the data drive circuit 130, the controller 140 can output various data control signals DCS, including the source start pulse SSP, the source sampling clock SSC, and the source output enable signal SOE.

[0047] The source start pulse SSP controls the data sampling start timing of one or more source driver integrated circuits (SDICs) constituting the data drive circuit 130. The source sampling clock SSC is a clock signal used to control the timing of the sampled data in each source driver integrated circuit (SDIC). The source output enable signal SOE controls the output timing of the data drive circuit 130.

[0048] The display device 100 may also include a power management integrated circuit, which is used to supply various voltages or currents to the display panel 110, the gate driving circuit 120, the data driving circuit 130, etc., or to control the various voltages or currents to be supplied to the display panel 110, the gate driving circuit 120, the data driving circuit 130, etc.

[0049] Depending on the type of display device 100, liquid crystal or light-emitting elements may be disposed on sub-pixels SP included in the display panel 110.

[0050] When the display device 100 is a liquid crystal display device, the display device 100 may include a backlight unit that supplies light to the display panel 110.

[0051] The backlight unit may include elements that emit light, as well as various optical components that improve the efficiency of the light emitted from the elements.

[0052] Embodiments of this disclosure can provide a method for reducing the overall thickness of the display device 100 by reducing the thickness of the backlight unit. Furthermore, embodiments of this disclosure can provide a method for improving the quality of the image displayed by the display device 100 while improving the image quality and reliability of the backlight unit.

[0053] Figure 2 This is a cross-sectional view of an example of a backlight unit according to an embodiment of the present disclosure. Figure 3 Is included Figure 2 Plan view and cross-sectional view of an example of the optical plate 250 in the backlight unit shown. Figure 4A and Figure 4B It shows the manufacturing process. Figure 3 A diagram illustrating an example of the method for using the optical plate 250.

[0054] Reference Figure 2 The backlight unit may include multiple light sources 220 and various optical components.

[0055] For example, the light source 220 can be a light-emitting diode (LED). The light source 220 can be a small LED with a size of hundreds of μm, or a micro LED with a size of tens of μm.

[0056] Multiple light-emitting diodes 220 can be mounted on the substrate 210.

[0057] For example, substrate 210 can be a printed circuit board. Substrate 210 can be a flexible printed circuit. In some cases, substrate 210 can be a substrate made of glass.

[0058] A reflector 230 may be provided on the substrate 210. The reflector 230 may be provided on at least a portion of the area on the substrate 210 where the light source 220 is not provided.

[0059] The reflector 230 may include a plurality of apertures H. At least some of the plurality of apertures H may be positioned to correspond to the light source 220, respectively.

[0060] The light source 220 can be positioned inside the aperture H included in the reflector 230. The light source 220 can be configured to be separate from the inner surface of the aperture H of the reflector 230.

[0061] The top of the reflector 230 can be positioned above the top of the light source 220.

[0062] The light source protection portion 240 can be disposed inside the aperture H of the reflector 230. The light source protection portion 240 can be configured to surround the light source 220.

[0063] For example, the light source protection part 240 may be made of resin, but is not limited to this.

[0064] The light source protection section 240 can perform the function of protecting the light source 220. The light source protection section 240 can also perform the function of guiding light emitted from the light source 220. The light source protection section 240 can be made of a material with a high refractive index, and can improve the diffusion performance of light emitted from the light source 220.

[0065] The light source protection portion 240 may not be located inside the aperture H of the reflector 230. In this case, an air layer may exist inside the aperture H of the reflector 230.

[0066] An optical plate 250 can be provided on the light source 220 and the reflector 230. An air layer can exist between the light source 220 and the optical plate 250.

[0067] At least one optical sheet 260 can be provided on the optical plate 250.

[0068] The substrate 210 on which the light source 220 is mounted and various optical components can be accommodated by the bottom of the cover 270.

[0069] The optical plate 250 may include multiple engraved patterns EP.

[0070] Multiple engraved patterns EP can be positioned on the bottom surface of the optical plate 250.

[0071] Each of the multiple engraved patterns EP can be positioned on an area corresponding to each of the multiple light sources 220. Each of the multiple engraved patterns EP can be positioned to correspond to the aperture H of the reflector 230.

[0072] A color conversion section 251 can be disposed within multiple engraved patterns EP. The color conversion section 251 may include a color conversion material, such as a phosphor. For example, the color conversion section 251 can be made by mixing a phosphor and a resin and placing them in the engraved pattern EP.

[0073] When the engraved pattern EP, in which a color conversion section 251 is provided, is positioned on the light source 220, the wavelength of the light emitted from the light source 220 can be converted by the color conversion section 251.

[0074] For example, light source 220 can emit blue light, and some of the blue light entering color conversion section 251 can be converted into green or red light. Therefore, white light can be supplied to display panel 110.

[0075] The color conversion section 251 can be configured to cover the top surface of the aperture H of the reflector 230 for wavelength conversion of light emitted from the light source 220. The size s1 of the engraved pattern EP can be greater than or equal to the size s2 of the aperture H.

[0076] The light whose wavelength is converted by the color conversion section 251 can be output to the upper region of the optical plate 250. The part of the optical plate 250 other than the engraved pattern EP can perform the function of guiding the light passing through the color conversion section 251.

[0077] For sufficient light guidance, the vertical distance d1 between the deepest point of the engraved pattern EP and the top surface of the optical plate 250 can be greater than the vertical distance d2 between the deepest point of the engraved pattern EP and the bottom surface of the optical plate 250.

[0078] Since the color conversion section 251 is located inside the engraved pattern EP and the optical plate 250 is located on the reflector 230, a structure for wavelength conversion of light emitted from the light source 220 can be easily realized.

[0079] Since the color conversion section 251 is located only on the light source 220, the wavelength conversion function can be achieved while reducing the amount of color conversion material used to implement the color conversion section 251.

[0080] Since the color conversion portion 251 is positioned inside the engraved pattern EP included in the optical plate 250, the color conversion portion 251 is not exposed to the outside. Because the color conversion portion 251 is not exposed to the outside, the color conversion material can be prevented from malfunctioning due to external factors such as moisture.

[0081] Because the embodiments of this disclosure reduce the amount of color conversion material and achieve the color conversion function, and prevent abnormalities in the color conversion material, the image quality of the backlight unit can be maintained and the reliability of the backlight unit can be improved.

[0082] The refractive index of the color conversion section 251 can be the same as or different from that of the optical plate 250. Since the color conversion section 251 is located inside the engraved pattern EP of the optical plate 250, the refractive index of the material constituting the color conversion section 251 can be different from that of the optical plate 250.

[0083] For example, by using a material with a refractive index higher than that of the optical plate 250 to construct the color conversion section 251, the diffusion performance of light passing through the color conversion section 251 can be improved.

[0084] Furthermore, the shape of the engraved pattern EP, which includes a color conversion section 251, can be different.

[0085] For example, refer to Figure 3 The engraved pattern EP can be a hemisphere or a hemisphere-like shape, such as in case A. Alternatively, the engraved pattern EP can be a cone shape, such as in case B.

[0086] The engraved pattern EP can have various shapes that can cover the hole H of the reflector 230.

[0087] The center of the engraved pattern EP can be the area where the light intensity emitted from the light source 220 is strongest. The engraved pattern EP can have a shape in which the depth of the engraved pattern EP decreases from the center of the engraved pattern EP to the outer edge of the engraved pattern EP.

[0088] Depending on the processing method, the optical plate 250 can be made using one or two or more materials.

[0089] For example, refer to Figure 4A The second material 402 can be disposed on the first material 401 to manufacture the optical plate 250. The first material 401 can be, for example, a material constituting the optical plate 250, such as PET, but is not limited thereto. The second material 402 can be, for example, a resin for curing.

[0090] The second material 402 can be applied to the first material 401 as a state before hardening (step 1).

[0091] The shape of the engraved pattern EP can be imprinted on the second material 402, and the second material 402 can be hardened (step 2).

[0092] The shape of the optical plate 250, including the engraved pattern EP, can be made of a first material 401 and a second material 402 hardened on the first material 401.

[0093] The color conversion portion 251 can be applied to the engraved pattern EP (step 3). For example, the color conversion portion 251 can be a mixture of phosphor and resin.

[0094] One surface of the optical plate 250 on which the color conversion portion 251 is applied can be polished, and the color conversion portion 251 set on the area other than the engraved pattern EP can be removed (step 4).

[0095] An optical plate 250 can be manufactured with a color conversion section 251 set inside the engraved pattern EP.

[0096] Since the first material 401 and the second material 402 are used to realize the optical plate 250, the light diffusion performance of the optical plate 250 can be improved by using materials with different refractive indices.

[0097] For another example, see Figure 4B The optical plate 250 can be manufactured using a single material.

[0098] To manufacture the optical plate 250, the first material 401 can be heated (step 1).

[0099] While the first material 401 is in a flexible state, for example, the shape of the engraved pattern EP can be imprinted onto the first material 401 by stamping (step 2).

[0100] The color conversion portion 251 can be applied to the engraved pattern EP (step 3). One surface of the optical plate 250 can be polished, and the optical plate 250 with the color conversion portion 251 disposed inside the engraved pattern EP can be manufactured (step 4).

[0101] Since the optical plate 250 is placed on the reflector 230, color conversion and light guiding functions can be easily implemented. This simplifies the manufacturing process of the backlight unit and provides a backlight unit that maintains image quality and improves the reliability of the color conversion section 251.

[0102] The optical plate 250 may also include at least one engraved pattern EP positioned in an area that does not correspond to the light source 220.

[0103] By arranging color conversion material or other materials in an engraved pattern EP positioned in an area that does not correspond to the light source 220, various functions that can improve the image quality of the backlight unit can be achieved.

[0104] Figures 5 to 7 This is a cross-sectional view of a backlight unit including an optical plate 250 according to an embodiment of the present disclosure.

[0105] Reference Figure 5 The optical plate 250 may include an engraved pattern EP positioned on an area corresponding to the light source 220. A color conversion portion 251, including a color conversion material, may be disposed inside the engraved pattern EP.

[0106] The optical plate 250 may include at least one auxiliary engraved pattern EPs positioned in an area other than the area overlapping with the light source 220.

[0107] For example, auxiliary engraving patterns EPs can be positioned along the outer edge of the optical plate 250. The outer edge of the optical plate 250 can refer to the area that overlaps with or is adjacent to the outer edge of the backlight unit.

[0108] Auxiliary engraving patterns (EPs) can be positioned around multiple engraving patterns (EPs).

[0109] The auxiliary color conversion section 252, including the color conversion material, can be set inside the auxiliary engraving pattern EPs.

[0110] The shape of the auxiliary engraving pattern EPs can be the same as the shape of the engraving pattern EP, or different from the shape of the engraving pattern EP.

[0111] For example, the depth of the auxiliary engraved pattern EPs can be less than the depth of the engraved pattern EP. The bottom surface of the engraved pattern EP can be a curved or inclined surface, while the bottom surface of the auxiliary engraved pattern EPs can be flat.

[0112] The size of the auxiliary engraving patterns EPs can be smaller than the size of the engraved pattern EP. The density of the color conversion material set in the auxiliary engraving patterns EPs can be smaller than the density of the color conversion material set in the engraved pattern EP.

[0113] Since the auxiliary engraving patterns EPs are not positioned on the light source 220, the light guided by the optical plate 250 can reach the auxiliary engraving patterns EPs.

[0114] The wavelength of light reaching the auxiliary engraved patterns EPs can be converted by the auxiliary color conversion section 252 inside the auxiliary engraved patterns EPs. By setting the auxiliary color conversion section 252 in the auxiliary engraved patterns EPs, the supply of white light can be increased at the outer edge of the optical plate 250.

[0115] This can reduce the difference in image quality between the central and outer edge areas of the backlight unit. It can improve the overall image quality of the backlight unit.

[0116] The auxiliary engraving patterns EPs can be set in the area where the hole H of the reflector 230 is not located.

[0117] The engraved pattern EP can be positioned on the following area of ​​the reflector 230: wherein the aperture H of the reflector 230 is positioned and the light source 220 is not located inside the aperture H.

[0118] Reference Figure 6 The optical plate 250 may include an engraved pattern EP positioned on the light source 220. The optical plate 250 may also include auxiliary engraved patterns EPs positioned along the outer edge of the optical plate 250. In some cases, the optical plate 250 may not include auxiliary engraved patterns EPs.

[0119] The optical plate 250 may include at least one additional engraved pattern EPa positioned on the aperture H of the reflector 230 where the light source 220 is not located.

[0120] The reflector 230 may include at least one aperture H in which no light source 220 is disposed. The size and shape of the aperture H in which no light source 220 is disposed may be the same as or different from the size and shape of the aperture H in which a light source 220 is disposed.

[0121] The circuit component 600 can be disposed inside the aperture H of the reflector 230 where the light source 220 is not located. The circuit component 600 can be, for example, a circuit for driving the light source 220 or a component for electrostatic discharge.

[0122] Since the circuit component 600 is disposed on the same surface as the surface on the substrate 210 where the light source 220 is disposed, the thickness of the backlight unit can be reduced. Since the circuit component 600 is positioned in the active region AA where the light source 220 is disposed, the area of ​​the non-active region NA can be reduced.

[0123] Since the hole H in which the circuit component 600 is located is between the light sources 220, it can be a region with a smaller amount of light compared to the region where the light source 220 is located.

[0124] An additional engraved pattern EPa can be positioned on the hole H in which the circuit component 600 is disposed. An additional color conversion section 253, including a color conversion material, can be disposed inside the additional engraved pattern EPa. The wavelength of light reaching the region between the light sources 220 can be converted by the additional color conversion section 253. The supply of white light can be increased in the region between the light sources 220.

[0125] The shape of the additional engraved pattern EPa can be similar to or different from the shape of the engraved pattern EP.

[0126] Since the additional engraved pattern EPa is positioned in an area with low light intensity, the depth of the additional engraved pattern EPa can be greater than the depth of the engraved pattern EP. The amount or density of the color conversion material set in the additional engraved pattern EPa can be greater than the amount or density of the color conversion material set in the engraved pattern EP.

[0127] Because the additional engraved pattern EPa containing color conversion material is positioned in the area between the light sources 220, the uniformity of white light can be improved.

[0128] The light-blocking layer can be further positioned to conceal the circuit component 600 positioned beneath the additional engraved pattern EPa. The light-blocking layer can be disposed on the outer surface of the additional color conversion portion 253. For example, the light-blocking layer can be disposed by printing ink onto the outer surface of the additional color conversion portion 253.

[0129] The supply of white light can be increased in the area where the circuit component 600 is set, and the circuit component 600 can be hidden.

[0130] When there is sufficient white light supplied to the area where the circuit component 600 is located, the function of hiding the circuit component 600 can be achieved by adding an engraved pattern EPa.

[0131] Reference Figure 7 The optical plate 250 may include an engraved pattern EP and auxiliary engraved patterns EPs. The optical plate 250 may include an additional engraved pattern EPa positioned on the circuit component 600.

[0132] The light-blocking portion 254, which includes a light-diffusing material, can be disposed within the additional engraved pattern EPa. For example, the light-blocking portion 254 can be achieved by mixing a light-diffusing material and a resin.

[0133] When the light blocking portion 254 is set in the additional engraved pattern EPa, the size or depth of the additional engraved pattern EPa can be smaller than the size or depth of the engraved pattern EP.

[0134] The concealment function of the circuit component 600 can be easily achieved through the light blocking part 254, and the structure of the backlight unit can be simplified.

[0135] Furthermore, embodiments of this disclosure can further improve the optical performance provided by the optical plate 250 by using an additional optical layer positioned on the upper or lower part of the optical plate 250.

[0136] Figures 8 to 12 This is a cross-sectional view of another example of a backlight unit according to an embodiment of the present disclosure.

[0137] In order to clearly describe the features, Figures 8 to 12 Cross-sections are shown for each backlight unit implemented with a different structure, but they can be combined. Figures 8 to 12 The backlight unit is implemented using at least two structures shown. Furthermore, various structures of the optical plate 250 described above can be combined. Figures 8 to 12 The structure shown is used to implement the backlight unit.

[0138] Reference Figure 8 The optical plate 250 can be positioned on the light source 220 and the reflector 230. The optical plate 250 may include an engraved pattern EP positioned on the light source 220 and in which a color conversion portion 251 is provided.

[0139] A color conversion layer 800, including a color conversion material, can be disposed on the top or bottom surface of the optical plate 250.

[0140] The color conversion layer 800 can be formed by applying a color conversion material to one surface of the optical plate 250. The color conversion layer 800 can be disposed separately from the optical plate 250.

[0141] The color conversion layer 800 can be considered as part of the optical plate 250, or in some cases, it can be a separate configuration from the optical plate 250.

[0142] The wavelength of light emitted by the color conversion material included in the color conversion section 251 may be different from the wavelength of light emitted by the color conversion material included in the color conversion layer 800.

[0143] In the color conversion materials included in the color conversion section 251 and the color conversion materials included in the color conversion layer 800, the wavelength of light emitted by the color conversion material positioned closer to the light source 220 can be greater than the wavelength of light emitted by the other color conversion material.

[0144] For example, if the light source 220 emits blue light, the color conversion material that emits red light can be positioned closer to the light source 220 than the color conversion material that emits green light.

[0145] For example, in case A, the color conversion layer 800 can be disposed on the top surface of the optical plate 250. In this case, the color conversion material included in the color conversion portion 251 disposed in the engraved pattern EP can emit red light. The color conversion material included in the color conversion layer 800 can emit green light.

[0146] For example, in case B, the color conversion layer 800 can be disposed on the bottom surface of the optical plate 250. In this case, the color conversion material included in the color conversion layer 800 can emit red light. The color conversion material included in the color conversion portion 251 disposed in the engraved pattern EP can emit green light.

[0147] The color conversion material that emits green light can be positioned higher than the color conversion material that emits red light.

[0148] Since the green light emitted by the color-converting material may not be converted into red light, the reduction in the amount of green light can be prevented.

[0149] In addition, layers that reflect specific wavelengths of light can be added to increase the supply of green and red light.

[0150] Reference Figure 9 The optical plate 250 can be mounted on the light source 220 and the reflector 230.

[0151] The reflection filter layer 900 can be disposed on the bottom surface.

[0152] The reflection filter layer 900 can be part of the optical plate 250, or it can be set separately from the optical plate 250.

[0153] The reflective filter layer 900 can transmit some wavelengths of light and reflect other wavelengths of light.

[0154] The reflective filter layer 900 can transmit light emitted by the light source 220. The reflective filter layer 900 can also reflect light emitted by the color conversion material located within the engraved pattern EP of the optical plate 250.

[0155] For example, the reflection filter layer 900 can transmit blue light and reflect green and red light. The reflection filter layer 900 can improve the efficiency of the light emitted by the color conversion section 251.

[0156] The reflection filter layer 900 can be completely disposed on the bottom surface of the optical plate 250, for example, case A.

[0157] Alternatively, the reflection filter layer 900 may be disposed on a portion of the bottom surface of the optical plate 250, including the area where the color conversion portion 251 is disposed.

[0158] In the structure shown in case B, the light source 220 may not need to be positioned, and the reflector 230 may be positioned in the area where the reflection filter layer 900 is not provided. For example, in the structure shown in case B, the light efficiency can be improved by minimizing the area where the reflection filter layer 900 is provided.

[0159] In addition, a layer for improving light diffusion performance can be added to at least one surface of the top or bottom surface of the optical plate 250.

[0160] Reference Figure 10 The light diffusion layer 1000, which includes multiple protrusions, can be disposed on at least one surface of the top or bottom surface of the optical plate 250.

[0161] The light diffusion layer 1000 can be in an embossed or engraved shape. The protrusions constituting the light diffusion layer 1000 can be lens-shaped, for example... Figure 10 The example shown can be made into various structures, such as pyramids, cones, V-shaped cuts, etc.

[0162] The light diffusion layer 1000 can be completely disposed on the top surface of the optical plate 250, for example, case A.

[0163] The light diffusion layer 1000 can be disposed on the bottom surface of the optical plate 250 in the area corresponding to the hole H of the reflector 230 in which the light source 220 is disposed, for example, in case B.

[0164] The light diffusion layer 1000 can be disposed on both the top and bottom surfaces of the optical plate 250.

[0165] Light diffusion performance can be improved by a light diffusion layer 1000 disposed on at least one surface of the top or bottom surface of the optical plate 250. Furthermore, the protruding shape of the light diffusion layer 1000 can form an intentional air layer on the upper part or upper portion of the optical plate 250, thereby improving light diffusion performance.

[0166] Alternatively, an air layer can be formed by the structure of the light source protection portion 240 provided on the light source 220.

[0167] Reference Figure 11 The light source 220 can be disposed in the aperture H of the reflector 230. The light source protection part 240 can surround the light source 220 and can also be disposed in the aperture H of the reflector 230.

[0168] The light source protection portion 240 can be configured to overflow the aperture H of the reflector 230. A portion of the light source protection portion 240 can be positioned around the aperture H of the reflector 230. The top of the light source protection portion 240 can be positioned above the top of the reflector 230.

[0169] The top surface of the light source protection section 240 can support the optical plate 250.

[0170] An air layer can be formed between the bottom surface of the optical plate 250 and the top surface of the reflector 230. The support strip 1100 can be disposed on the reflector 230 in the area between the light sources 220 and can support the optical plate 250.

[0171] and Figure 11 In contrast to the structure shown, the light source protection portion 240 may be inadequately disposed in the hole H of the reflector 230.

[0172] The top of the light source protection part 240 can be positioned below the top of the reflector 230.

[0173] The optical plate 250 can be supported by the reflector 230. An air layer can be formed between the optical plate 250 and the light source protection part 240.

[0174] For example Figure 10 and Figure 11 The structure shown can improve light diffusion performance by forming an air layer on the upper or lower part of the optical plate 250 using the structure of the light diffusion layer 1000 or the light source protection part 240.

[0175] Furthermore, light diffusion performance can be improved by arranging light scattering material in at least a portion of the interior of the optical plate 250.

[0176] Reference Figure 12 A light-scattering material such as TiO2 or SiO2 can be provided in at least a portion of the optical plate 250. TiO2 and SiO2 can be provided in the same proportion or in different proportions.

[0177] For example, in case A, the light-scattering material can be disposed in the first portion 250a of the optical plate 250. The light-scattering material may not be disposed in the second portion 250b of the optical plate 250.

[0178] The first portion 250a of the optical plate 250 may be a portion surrounding the engraved pattern EP. Since light passing through the color conversion portion 251 inside the engraved pattern EP is scattered in the first portion 250a of the optical plate 250, the efficiency of the color conversion material included in the color conversion portion 251 can be improved.

[0179] Alternatively, for example, in case B, the light scattering material can be entirely disposed within the optical plate 250. Two or more types of light scattering materials can be disposed within the optical plate 250. By adjusting the ratio of the two or more types of light scattering materials disposed within the optical plate 250, the wavelength conversion efficiency and image quality of the optical plate 250, which is equipped with the color conversion section 251, can be improved.

[0180] The implementation methods of the above-described disclosure will be briefly described below.

[0181] A backlight unit according to an embodiment of the present disclosure may include: a plurality of light sources 220 disposed on a substrate 210; a reflector 230 disposed on the substrate 210 and including a plurality of holes H, wherein at least some of the plurality of holes H are positioned to correspond to each of the plurality of light sources 220; and an optical plate 250 positioned on the plurality of light sources 220 and the reflector 230, wherein the optical plate 250 includes a plurality of engraved patterns EP positioned on a bottom surface in areas corresponding to each of the plurality of light sources 220, wherein a color conversion portion 251 including a color conversion material is disposed inside each of the plurality of engraved patterns EP.

[0182] The size of each of the multiple engraved patterns EP can be greater than or equal to the size of each of the multiple holes H.

[0183] The vertical distance between the deepest point in multiple engraved patterns EP and the top surface of the optical plate 250 can be greater than the vertical distance between that point and the bottom surface of the optical plate 250.

[0184] The refractive index of the color conversion section 251 can be greater than or equal to the refractive index of the optical plate 250.

[0185] The optical plate 250 may further include at least one auxiliary engraved pattern EPs positioned along the outer edge of the optical plate 250, wherein an auxiliary color conversion portion 252 including a color conversion material is disposed in the at least one auxiliary engraved pattern EPs.

[0186] At least one auxiliary engraving pattern EPs can be positioned on an area other than the area overlapping with the multiple light sources 220.

[0187] The depth of at least one auxiliary engraving pattern EP can be less than the depth of each of the multiple engraving patterns EP.

[0188] At least one auxiliary engraved pattern EPs can be positioned on the two surfaces of the optical plate 250, and multiple engraved patterns EPs are positioned on the surface thereon.

[0189] The optical plate 250 may also include at least one additional engraved pattern EPa, which is located in an area other than the area corresponding to each of the plurality of light sources 220 and in an area corresponding to one of the plurality of apertures H.

[0190] The circuit component 600 can be disposed inside the hole H corresponding to at least one additional engraved pattern EPa among a plurality of holes H.

[0191] An additional color conversion portion 253, including a color conversion material, can be disposed inside at least one additional engraved pattern EPa. Furthermore, a light-blocking layer can be disposed on the outer surface of the additional color conversion portion 253 exposed to the outside of the optical plate 250.

[0192] Alternatively, a light-blocking portion 254, including a light-diffusing material, may be disposed inside at least one additional engraved pattern EPa.

[0193] The backlight unit may also include a color conversion layer 800 disposed on the top or bottom surface of the optical plate 250 and comprising a color conversion material. Among the color conversion materials included in the color conversion portion 251 and the color conversion materials included in the color conversion layer 800, the wavelength of light emitted by the color conversion material closer to the plurality of light sources 220 may be greater than the wavelength of light emitted by the other color conversion material.

[0194] The backlight unit may also include a reflective filter layer 900 disposed on at least a portion of the area between the optical plate 250 and the plurality of light sources 220. The reflective filter layer 900 transmits light emitted from the plurality of light sources 220 and reflects light emitted by the color conversion material.

[0195] The backlight unit may also include a light diffusion layer 1000, which is disposed on at least one surface of the top or bottom surface of the optical plate 250 and includes a plurality of protrusions. The light diffusion layer 1000 may be disposed on the bottom surface of the optical plate 250 and positioned in an area overlapping with each of the plurality of engraved patterns EP.

[0196] An air layer may exist between the multiple light sources 220 and the optical plate 250, or between the reflector 230 and the optical plate 250.

[0197] At least a portion of the optical plate 250 may include a light-scattering material.

[0198] The backlight unit according to the embodiments of the present disclosure may include: a plurality of light sources 220 disposed on a substrate 210; a reflector 230 disposed on the substrate 210, and the reflector 230 is disposed on at least a portion of the region other than the region where the plurality of light sources 220 are disposed; and an optical plate 250 positioned on the reflector 230.

[0199] The optical plate 250 may include a plurality of first engraved patterns positioned on an area corresponding to each of the plurality of light sources 220, and at least one second engraved pattern positioned on an area other than the area corresponding to each of the plurality of light sources 220. A color conversion portion including a color conversion material may be disposed within the plurality of first engraved patterns and at least one second engraved pattern.

[0200] According to embodiments of this disclosure, by arranging the color conversion material inside the engraved pattern EP included in the optical plate 250, changes in the properties of the color conversion material caused by external factors can be prevented.

[0201] Since the optical plate 250, in which the color conversion material is placed inside the engraved pattern EP, is placed on the light source 220 and the reflector 230, the amount of color conversion material can be reduced, and a backlight unit that provides a certain level of image quality can be easily achieved.

[0202] Furthermore, the optical plate 250 may also include auxiliary engraved patterns EPs or additional engraved patterns EPa positioned on an area other than the area overlapping with the light source 220. If desired, color conversion material or light diffusion material can be disposed within the auxiliary engraved patterns EPs and additional engraved patterns EPa. With the auxiliary engraved patterns EPs and additional engraved patterns EPa, a backlight unit with improved image quality and a simplified structure can be easily achieved.

[0203] The above description is presented to enable any person skilled in the art to make and use the technical concepts of this disclosure, and has been provided in the context of a particular application and its requirements. Various modifications, additions, and substitutions to the described embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this disclosure. The above description and figures provide examples of the technical concepts of this disclosure for illustrative purposes only. That is, the disclosed embodiments are intended to illustrate the scope of the technical concepts of this disclosure. Therefore, the scope of this disclosure is not limited to the illustrated embodiments, but should be given the widest scope consistent with the claims. The scope of protection of this disclosure should be interpreted based on the following claims, and all technical concepts within their equivalent scope should be interpreted as including within the scope of this disclosure.

[0204] Note that this technology can have the following configurations.

[0205] (1). A display device, comprising:

[0206] Display panel; and

[0207] A backlight unit, configured to supply light to the display panel, and

[0208] The backlight unit includes:

[0209] Multiple light sources on the substrate;

[0210] The reflector on the substrate includes a plurality of holes, wherein at least some of the plurality of holes are configured to accommodate each of the plurality of light sources; and

[0211] An optical plate, positioned on the plurality of light sources and the reflector, wherein the optical plate includes a plurality of engraved patterns on a bottom surface corresponding to each of the plurality of light sources and a color conversion portion comprising a color conversion material disposed within the plurality of engraved patterns.

[0212] (2). The display device according to (1), wherein the size of the plurality of engraved patterns is greater than or equal to the size of each of the plurality of holes.

[0213] (3). The display device according to (1), wherein the vertical distance between the deepest point of the plurality of engraved patterns and the top surface of the optical plate is greater than the vertical distance between the deepest point and the bottom surface of the optical plate.

[0214] (4). The display device according to (1), wherein the refractive index of the color conversion portion is greater than or equal to the refractive index of the optical plate.

[0215] (5). The display device according to (1), wherein the optical plate further includes:

[0216] At least one auxiliary engraved pattern is positioned along the outer edge of the optical plate, wherein an auxiliary color conversion portion comprising a color conversion material is disposed in the at least one auxiliary engraved pattern.

[0217] (6). The display device according to (5), wherein the at least one auxiliary engraved pattern does not overlap with the plurality of light sources.

[0218] (7). The display device according to (5), wherein the depth of the at least one auxiliary engraved pattern is less than the depth of each of the plurality of engraved patterns.

[0219] (8). The display device according to (5), wherein the at least one auxiliary engraved pattern is positioned on one of the two surfaces of the optical plate and the plurality of engraved patterns are positioned on the surface thereon.

[0220] (9). The display device according to (1), wherein the optical plate further includes:

[0221] At least one additional engraved pattern is positioned on the area corresponding to the hole among the plurality of holes that does not accommodate the plurality of light sources.

[0222] (10). The display device according to (9), wherein a circuit component is received in one of the plurality of holes corresponding to the at least one additional engraved pattern.

[0223] (11). The display device according to (9), wherein an additional color conversion portion including a color conversion material is disposed inside the at least one additional engraved pattern.

[0224] (12). The display device according to (11) further includes:

[0225] A light-blocking layer is disposed on the outer surface of the additional color conversion portion exposed to the outside of the optical plate.

[0226] (13). The display device according to (9), wherein a light-blocking portion comprising a light-diffusing material is disposed inside the at least one additional engraved pattern.

[0227] (14). The display device according to (1) further includes:

[0228] A color conversion layer, wherein the color conversion layer is disposed on the top or bottom surface of the optical plate and comprises a color conversion material, and

[0229] Among the color conversion materials included in the color conversion portion and the color conversion materials included in the color conversion layer, the wavelength of light emitted by the color conversion material closer to the plurality of light sources is greater than the wavelength of light emitted by the other color conversion material.

[0230] (15). The display device according to (1) further includes:

[0231] A reflection filter layer is disposed on at least a portion of the area between the optical plate and the plurality of light sources, the reflection filter layer transmitting light emitted from the plurality of light sources and reflecting light emitted by the color conversion material.

[0232] (16). The display device according to (1) further includes:

[0233] A light diffusion layer is disposed on at least one surface of the top or bottom surface of the optical plate and includes a plurality of protrusions.

[0234] (17). The display device according to (16), wherein the light diffusion layer is disposed on the bottom surface of the optical plate and overlaps with each of the plurality of engraved patterns.

[0235] (18). The display device according to (1), wherein there is an air layer between the plurality of light sources and the optical plate, or between the reflector and the optical plate.

[0236] (19). The display device according to (1), wherein at least a portion of the optical plate comprises a light-scattering material.

[0237] (20). A backlight unit, comprising:

[0238] Multiple light sources on the substrate;

[0239] The reflector on the substrate includes a plurality of holes, wherein at least some of the plurality of holes are configured to accommodate each of the plurality of light sources; and

[0240] An optical plate, positioned on the plurality of light sources and the reflector, wherein the optical plate includes a plurality of engraved patterns on a bottom surface corresponding to each of the plurality of light sources and a color conversion portion comprising a color conversion material disposed within the plurality of engraved patterns.

[0241] (21). A backlight unit, comprising:

[0242] Multiple light sources on the substrate;

[0243] The reflector on the substrate, the reflector being disposed on at least a portion of the region that does not overlap with the plurality of light sources; and

[0244] An optical plate positioned on the reflector, and

[0245] The optical plate includes:

[0246] A plurality of first engraved patterns corresponding to each of the plurality of light sources, and at least one second engraved pattern not corresponding to any of the plurality of light sources.

[0247] The color-converting portion, including the color-converting material, is disposed within the plurality of first engraved patterns and the at least one second engraved pattern.

[0248] (22). A display comprising:

[0249] Display panel; and

[0250] A backlight unit, configured to supply light to the display panel, and

[0251] The backlight unit includes:

[0252] Multiple light sources on the substrate;

[0253] The reflector on the substrate, the reflector being disposed on at least a portion of the region that does not overlap with the plurality of light sources; and

[0254] An optical plate positioned on the reflector, and

[0255] The optical plate includes:

[0256] A plurality of first engraved patterns corresponding to each of the plurality of light sources, and at least one second engraved pattern not corresponding to any of the plurality of light sources.

[0257] The color-converting portion, including the color-converting material, is disposed within the plurality of first engraved patterns and the at least one second engraved pattern.

Claims

1. A display device, comprising: Display panel; and A backlight unit, configured to supply light to the display panel, and The backlight unit includes: Multiple light sources on the substrate; The reflector on the substrate includes a plurality of holes, wherein at least some of the plurality of holes are configured to accommodate each of the plurality of light sources; and An optical plate, positioned on the plurality of light sources and the reflector, wherein the optical plate includes a plurality of engraved patterns on a bottom surface corresponding to each of the plurality of light sources, and a color conversion portion comprising a color conversion material disposed within the plurality of engraved patterns. The optical plate further includes: At least one auxiliary engraved pattern is positioned along the outer edge of the optical plate, and wherein an auxiliary color conversion portion comprising a color conversion material is disposed in the at least one auxiliary engraved pattern. Wherein, the at least one auxiliary engraving pattern does not overlap with the plurality of light sources.

2. The display device according to claim 1, wherein, The size of the plurality of engraved patterns is greater than or equal to the size of each of the plurality of holes.

3. The display device according to claim 1, wherein, The vertical distance between the deepest point of the plurality of engraved patterns and the top surface of the optical plate is greater than the vertical distance between the deepest point and the bottom surface of the optical plate.

4. The display device according to claim 1, wherein, The refractive index of the color conversion section is greater than or equal to the refractive index of the optical plate.

5. The display device according to claim 1, wherein, The depth of the at least one auxiliary engraving pattern is less than the depth of each of the plurality of engraving patterns.

6. The display device according to claim 1, wherein, The at least one auxiliary engraved pattern is positioned on one of the two surfaces of the optical plate, and the plurality of engraved patterns are positioned on the surface thereon.

7. The display device according to claim 1, wherein, The optical plate also includes: At least one additional engraved pattern is positioned on the area corresponding to the hole among the plurality of holes that does not accommodate the plurality of light sources.

8. The display device according to claim 7, wherein, The hole in the plurality of holes that corresponds to the at least one additional engraved pattern houses the circuit component.

9. The display device according to claim 7, wherein, An additional color-converting portion, including color-converting material, is disposed within the at least one additional engraved pattern.

10. The display device according to claim 9, further comprising: A light-blocking layer is disposed on the outer surface of the additional color conversion portion exposed to the outside of the optical plate.

11. The display device according to claim 7, wherein, A light-blocking portion, including a light-diffusing material, is disposed within the at least one additional engraved pattern.

12. The display device according to claim 1, further comprising: A color conversion layer, wherein the color conversion layer is disposed on the top or bottom surface of the optical plate and comprises a color conversion material, and Among the color conversion materials included in the color conversion portion and the color conversion materials included in the color conversion layer, the wavelength of light emitted by the color conversion material closer to the plurality of light sources is greater than the wavelength of light emitted by the other color conversion material.

13. The display device according to claim 1, further comprising: A reflection filter layer is disposed on at least a portion of the area between the optical plate and the plurality of light sources, the reflection filter layer transmitting light emitted from the plurality of light sources and reflecting light emitted by the color conversion material.

14. The display device according to claim 1, further comprising: A light diffusion layer is disposed on at least one surface of the top or bottom surface of the optical plate and includes a plurality of protrusions.

15. The display device according to claim 14, wherein, The light diffusion layer is disposed on the bottom surface of the optical plate and overlaps with each of the plurality of engraved patterns.

16. The display device according to claim 1, wherein, An air layer exists between the plurality of light sources and the optical plate, or between the reflector and the optical plate.

17. The display device according to claim 1, wherein, At least a portion of the optical plate includes a light-scattering material.

18. A backlight unit, comprising: Multiple light sources on the substrate; The reflector on the substrate includes a plurality of holes, wherein at least some of the plurality of holes are configured to accommodate each of the plurality of light sources; and An optical plate, positioned on the plurality of light sources and the reflector, wherein the optical plate includes a plurality of engraved patterns on a bottom surface corresponding to each of the plurality of light sources, and a color conversion portion comprising a color conversion material disposed within the plurality of engraved patterns. The optical plate further includes: At least one auxiliary engraved pattern is positioned along the outer edge of the optical plate, and wherein an auxiliary color conversion portion comprising a color conversion material is disposed in the at least one auxiliary engraved pattern. Wherein, the at least one auxiliary engraving pattern does not overlap with the plurality of light sources.

19. A backlight unit, comprising: Multiple light sources on the substrate; The reflector on the substrate is disposed on at least a portion of the region that does not overlap with the plurality of light sources; as well as An optical plate positioned on the reflector, and The optical plate includes: A plurality of first engraved patterns corresponding to each of the plurality of light sources, and at least one second engraved pattern not corresponding to any of the plurality of light sources. The color-converting portion, including the color-converting material, is disposed within the plurality of first engraved patterns and the at least one second engraved pattern.

20. A display comprising: Display panel; and A backlight unit, configured to supply light to the display panel, and The backlight unit includes: Multiple light sources on the substrate; The reflector on the substrate, the reflector being disposed on at least a portion of the region that does not overlap with the plurality of light sources; and An optical plate positioned on the reflector, and The optical plate includes: A plurality of first engraved patterns corresponding to each of the plurality of light sources, and at least one second engraved pattern not corresponding to any of the plurality of light sources. The color-converting portion, including the color-converting material, is disposed within the plurality of first engraved patterns and the at least one second engraved pattern.

Images