Signboard display device and driving method thereof

Abstract

The display device for a signboard of an embodiment of the present application includes: an LED package having a plurality of LED groups; an illuminance sensor for detecting the illuminance of external light; and a control unit for controlling the LED package according to the illuminance sensor; the plurality of LED groups each have a different forward voltage, and the control unit can drive the LED package in different modes according to the illuminance sensor.

Description

Technical Field

[0001] This invention relates to a display device for signage and its driving method. Background Technology

[0002] Digital signage, as a display device that uses digital information displays (DIDs) installed inside and outside buildings, is a device that provides images or videos, including advertisements or various information.

[0003] There are two types of digital signage: outdoor digital signage and indoor digital signage.

[0004] Outdoor digital signage refers to digital signage installed on the exterior walls of buildings, electronic billboards, or externally for purposes such as outdoor cinemas. Indoor digital signage refers to digital signage installed on the interior walls of large shopping malls or in the form of freestanding signs.

[0005] When digital signage is used in outdoor environments, high-brightness light is required to improve visibility during the day in strong sunlight.

[0006] However, when digital signage is used at night, there is no need to use high-brightness light, and in various countries or regions, the maximum brightness value for nighttime use is being restricted.

[0007] The typical range of maximum usable brightness at night is 100 to 300 nits. If the brightness is limited to this, the current of the existing driver IC is fixed, so in order to reduce the brightness, only a low bit color depth can be used, which causes image quality problems at low gray levels (0 to 36 gray).

[0008] To address this issue, although an organic light-emitting diode (LED) package with added low grayscale compensation was developed in-house, side effects such as no-lighting and flickering caused by the application of low grayscale compensation technology still exist. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] The present invention provides a signage display device and its driving method, wherein the signage display device improves color depth at low gray levels even at night when brightness is limited.

[0011] The present invention provides a signage display device and its driving method, wherein the signage display device prevents color block accumulation at low grayscale levels.

[0012] The present invention provides a signage display device and its driving method, wherein the signage display device prevents the phenomenon of not being lit at low gray levels.

[0013] The present invention provides a signage display device and its driving method, wherein the signage display device prevents flickering at low grayscale levels.

[0014] means for solving problems

[0015] An embodiment of the signage display device of the present invention may include: an organic light-emitting diode (LED) package having a plurality of LED groups; an illuminance sensor for detecting the illuminance of external light; and a control unit for controlling the LED package according to the illuminance sensor; wherein the plurality of LED groups may each have different forward voltages, and the control unit may drive the LED package in different modes according to the illuminance sensor.

[0016] The LED package may include a first LED group and a second LED group. The first LED group includes a first Red (red light) chip, a first Green (green light) chip, and a first Blue (blue light) chip. The second LED group includes a second Red chip, a second Green chip, and a second Blue chip. The forward voltage of the second LED group may be smaller than that of the first LED group.

[0017] If the illuminance sensor determines that the external environment is daytime, the control unit can drive the LED package in daytime mode. In daytime mode, the LED package can drive the first LED group but not the second LED group.

[0018] If the illuminance sensor determines that the external environment requires high-brightness light, the control unit can drive the LED package in a high dynamic range (HDR) mode. In the HDR mode, the LED package can drive all of the first LED group and the second LED group.

[0019] If the illuminance sensor determines that the external environment is nighttime, the control unit can drive the LED package in nighttime mode. In nighttime mode, the LED package can drive only the second LED group instead of the first LED group.

[0020] As a method for driving a signage display device, the control unit can control the LED package to a daytime mode, an HDR mode, and a nighttime mode according to the illuminance sensor, and the amount of current applied to the LED package can vary depending on the mode.

[0021] When the control unit drives the LED package to night mode, the current applied to the LED package can be smaller than the current applied to the LED package in day mode and HDR mode.

[0022] The effects of the invention

[0023] The signage display device 1000 according to an embodiment may include a first LED group 100 and a second LED group 200.

[0024] At this time, in the night mode of the signage display device 1000 according to the embodiment, the LED package can be limited to a specified light intensity, for example, a brightness of 300 nits. For example, in the night mode of the signage display device 1000 according to the embodiment, the LED package 10P can drive only the second LED group 200.

[0025] Because the second LED group 200 consumes less driving current, it can achieve a 14-bit color depth even at low grayscale levels. Therefore, it can prevent unlit areas and color block accumulation even at low grayscale levels.

[0026] In this embodiment, the second LED group 200 can perform the offset function of the first LED group 100. That is, the LED package can be lit by the second LED group 200.

[0027] Since the second LED group 200 has a lower forward voltage than the first LED group 100, it can be different from the existing offset and has less impact on image quality.

[0028] Furthermore, since the first LED group 100 and the second LED group 200 have different forward voltages Vf, i.e., different amplitudes, lighting can be achieved at low grayscale levels using only the second LED group 200. This prevents color block accumulation at low grayscale levels and the phenomenon of no lighting at low grayscale levels within a specified range.

[0029] In addition, in an embodiment, the control unit 20 can control the mode of the display 1 based on the amount of light identified in the illuminance sensor 30.

[0030] For example, the display device 1000 for signage may include a daytime mode, an HDR mode, and a nighttime mode.

[0031] If the external environment is identified as daytime based on the amount of light detected by the illuminance sensor 30, the control unit 20 can control the signage display device 1000 to daytime mode. In the daytime mode of the signage display device 1000, the LED package 10P can drive only the first LED group 100, without driving the second LED group 200.

[0032] The control unit 20 can control the LED package 10P to HDR mode based on the amount of light detected by the illuminance sensor 30, during periods or seasons when the external environment is sunny or bright. In the HDR mode of the signage display device 1000, the LED package 10P can drive all of the first LED group 100 and the second LED group 200.

[0033] If the external environment is identified as nighttime based on the amount of light detected in the illuminance sensor 30, the control unit 20 can control the signage display device 1000 to nighttime mode. In nighttime mode of the signage display device 1000, the LED package 10P can drive only the second LED group 200, without driving the first LED group 100.

[0034] Because the current range of the second LED group 200 is small, it can display low grayscale with high color depth even at low brightness levels below 300 nits.

[0035] Since the current range of the second LED group 200 is smaller than that of the first LED group 100, it can reduce energy consumption in night mode.

[0036] Furthermore, since the LED groups driven in different modes are different, the current applied to the LED package in each mode can be configured differently. This prevents low grayscale unlit phenomena, color block accumulation, and flickering in night mode.

[0037] Furthermore, as a signage display device according to an embodiment of the present invention, since it has 14-bit expressive power, it has the technical effect of not causing unlit phenomena in the low grayscale range, and not causing problems such as color block accumulation and pixel unevenness. Attached Figure Description

[0038] Figure 1a This is an example diagram of a display device 1000 including semiconductor light-emitting elements for display pixels in an embodiment.

[0039] Figure 1b This is a perspective view of one of the plurality of display modules 1200 included in the display device 1000 of the embodiment.

[0040] Figure 1c This is a top view of a display panel 1210 included in the embodiment.

[0041] Figure 2 This is a diagram illustrating an LED package of a signage display device according to an embodiment of the present invention.

[0042] Figure 3 This is a diagram showing the brightness and color depth of the signage display device with internal technology.

[0043] Figure 4 This is a graph showing the brightness and grayscale levels of an LED package in HDR mode of a signage display device according to an embodiment of the present invention.

[0044] Figure 5 This is a graph showing the brightness and grayscale of the LED package in night mode of a display according to an embodiment of the present invention.

[0045] Figure 6 This is a diagram showing the constant current waveform of a signage display device using existing internal technology.

[0046] Figure 7 This is a diagram illustrating the pulse width modulation (PWM) of each frame in the signage display device, which is based on internal technology.

[0047] Figure 8 It is a graph showing the side effects of applying offset when used in a signage display device with internal technology.

[0048] Figure 9 This is a diagram showing the waveform of a signage display device 1000 according to an embodiment of the present invention.

[0049] Figure 10 This is a PWM diagram of a signage display device 1000 according to an embodiment of the present invention.

[0050] Figure 11 This is a diagram illustrating the configuration of a signage display device according to an embodiment of the present invention.

[0051] Figure 12 This is a graph showing the gamma curve of a signage display device in the prior art and the gamma curve of an embodiment of the present invention.

[0052] Figure 13 These are photographs comparing the performance of a signage display device using internal technology with that of a signage display device according to an embodiment of the present invention. Detailed Implementation

[0053] The following description, with reference to the accompanying drawings, illustrates a concrete implementation of an embodiment for solving the aforementioned problem.

[0054] When describing embodiments, the term "on or under" refers to the formation of each structure. "On or under" includes structures formed by two structures directly contacting each other or by one or more different structures disposed indirectly between the other two structures. Furthermore, when using "on or under," the term is based on a single structure and can include not only the meaning of the upward direction but also the meaning of the downward direction.

[0055] Figure 1a This is an example diagram of a display device 1000 including semiconductor light-emitting elements for display pixels according to an embodiment. The display device 1000 of the embodiment may include an assembled plurality of display modules 1200.

[0056] The display device 1000 of this embodiment can be applied to digital signage. For example, Figure 3 'a' can be an example of indoor digital signage, but the display device 1000 of the embodiment can also be applied to outdoor digital signage.

[0057] Figure 1b This is a perspective view of one of the plurality of display modules 1200 included in the display device 1000 of the embodiment.

[0058] Figure 1b The display panels 1200 shown can be installed in their respective housings and assembled in a block-like manner to realize the display device 1000 of the embodiment.

[0059] The display module 1200 of the embodiment may include: a plurality of display panels 1210 for outputting images; a module holder 1220 on which the display panels 1210 are disposed; and a module cover 1230 disposed on the outside of the module holder 1220.

[0060] A plurality of the aforementioned display panels 1210 can be arranged in a grid pattern on the module holder 1220 to form a display module 1200. Individual display modules 1200 can be assembled in a predetermined cabinet form to realize the display device 1000 of the embodiment. Display data can be transmitted in wired or wireless manner in the assembled individual display modules 1200.

[0061] Figure 1cThis is a top view of a display panel 1210 included in the embodiment.

[0062] Reference Figure 1c The display panel 1210 in the embodiment may include a semiconductor light-emitting element 10 for implementing each pixel.

[0063] For example, although the semiconductor light-emitting element 10 for display pixels in the embodiment may include a first semiconductor light-emitting element 10a, a second semiconductor light-emitting element 10b and a third semiconductor light-emitting element 10c, it is not limited thereto.

[0064] Each of the first semiconductor light-emitting elements 10a to the third semiconductor light-emitting elements 10c can form an individual subpixel and be repeatedly arranged. For example, although the first semiconductor light-emitting element 10a, the second semiconductor light-emitting element 10b, and the third semiconductor light-emitting element 10c can be a red light-emitting element, a green light-emitting element, and a blue light-emitting element, respectively, it is not limited to this. For example, each of the first semiconductor light-emitting elements to the third semiconductor light-emitting element may include a red light-emitting element, a green light-emitting element, and a blue light-emitting element.

[0065] The first semiconductor light-emitting element 10a, the second semiconductor light-emitting element 10b, and the third semiconductor light-emitting element 10c may have a size of micrometer (μm). The size of micrometer (μm) may refer to the width of at least one side of the light-emitting element being several μm to several hundred μm.

[0066] Figure 2 This is a diagram showing an LED package 10P of a signage display device 1000 according to an embodiment of the present invention.

[0067] The LED package 10P of the signage display device in this embodiment may include a first LED group 100 and a second LED group 200.

[0068] The first LED group 100 may include a first Red chip 110, a first Green chip 120, and a first Blue chip 130.

[0069] The second LED group 200 may include a second Red chip 210, a second Green chip 220, and a second Blue chip 230.

[0070] The current range of the second LED group 200 can be smaller than that of the first LED group 100.

[0071] The forward voltage Vf of the first LED group 100 may be different from the forward voltage Vf of the second LED group 200.

[0072] As an example, the current range of the first LED group 100 can be 1mA to 10mA, and the current range of the second LED group 200 can be 0.1mA to 1mA.

[0073] Figure 3 This is a diagram showing the brightness and color depth of the signage display device with internal technology.

[0074] Figure 3 (a) is a graph showing the relationship between brightness and grayscale when the signage display device of the internal technology is used in daytime conditions.

[0075] Figure 3 (b) is a graph showing the relationship between brightness and grayscale when the signage display device of the internal technology is used at night.

[0076] exist Figure 3 (a) and Figure 3 In (b), the x-axis of the graph represents the gray level, the y-axis represents the brightness, and the slope represents the current.

[0077] The LED package of the signage display device for internal technology can have an LED group.

[0078] In signage display devices using internal technology, indoor driver ICs are mainly used. In the case of such indoor driver ICs, the current can be fixed and the maximum current can be limited.

[0079] Therefore, if the signage display device with internal technology is used at night with a brightness limited to 300 nits, there is a problem that it is difficult to fully display the 14-bit color depth.

[0080] Figure 4 This is a graph showing the brightness and grayscale levels of an LED package in HDR mode of a signage display device according to an embodiment of the present invention.

[0081] One embodiment of the signage display device can be driven in multiple modes. As an example, if a brighter brightness than the existing brightness is required during periods of strong sunlight or in certain seasons, it is driven in HDR mode.

[0082] If the signage display device 1000 is driven in the HDR mode, the LED package 10P can drive both the first LED group 100 and the second LED group 200.

[0083] That is, when driven in HDR mode, the signage display 1 can have a brightness of more than 3,500 nits.

[0084] Figure 5 This is a graph showing the brightness and grayscale of the LED package in night mode of a display according to an embodiment of the present invention.

[0085] In the night mode of the signage display device 1000 in one embodiment, the LED package can be limited to a brightness of 300 nits.

[0086] In the night mode of the signage display device 1000 in one embodiment, the LED package 10P can drive only the second LED group 200.

[0087] Because the second LED group 200 consumes less driving current, it can also have a 14-bit color depth even at low gray levels.

[0088] Therefore, even at low grayscale levels, it can prevent the phenomenon of unlit areas and color block accumulation.

[0089] Figure 6 This is a diagram showing the constant current waveform of a signage display device according to existing internal technology. Figure 7 This is a diagram showing the PWM of each frame of the signage display device, illustrating the internal technology. Figure 8 The curve shows the side effects of offset when applied in a signage display device with internal technology.

[0090] The internal technical signage display device differs from the ideal constant current waveform; the actual waveform is formed with a slope.

[0091] Because the actual waveform has a slope in the internal technology, if the LED lighting time is shortened at low gray levels, a positive voltage cannot be formed on the LED package A, resulting in the LED not lighting up.

[0092] In an internal technology to address this problem, efforts were made to achieve a positive voltage for LED package A by adding offset or merging subframe units of PWM.

[0093] Reference Figure 6 The internal technology adds a specified offset to the LED package A during the operation of a subframe, so that the positive voltage Vf of the LED package A can be achieved.

[0094] However, since adding an offset would increase the width of the PWM for each subframe, therefore, as in Figure 7 As observed, the side effect of increasing the initial light intensity and producing an inflection point may occur.

[0095] Reference Figure 7 The PWM of the subframe unit of the LED package A is combined with the internal technology to enable the positive voltage of the LED package A to be achieved.

[0096] However, due to the superposition of PWM from different subframes, there is a problem that the light does not emit light in the subframes without PWM, resulting in flickering.

[0097] Reference Figure 8 When an offset is applied to a signage display device with internal technology, that is, when the function of adding a PWM (Offset) of a specified length every 1 Subframe is applied, there is a problem that the change in output brightness characteristics before and after the inflection point of the output characteristics increases.

[0098] Figure 9 The waveform of a signage display device 1000 according to an embodiment of the present invention is shown. Figure 10 A PWM graph of a signage display device 1000 according to an embodiment of the present invention is shown.

[0099] The signage display device 1000 of the embodiment may include a first LED group 100 and a second LED group 200.

[0100] The second LED group 200 can perform the offset function of the first LED group 100. That is, the LED package can be lit by the second LED group 200.

[0101] Since the second LED group 200 has a lower forward voltage than the first LED group 100, it can be different from the existing offset and has less impact on image quality.

[0102] In addition, since the first LED group 100 and the second LED group 200 have different forward voltages Vf, that is, they have different amplitudes, lighting can be achieved at low gray levels using only the second LED group 200.

[0103] This can prevent color block accumulation at low gray levels and the phenomenon of not being lit at low gray levels within a specified range.

[0104] Figure 11 This is a diagram illustrating the configuration of a signage display device according to an embodiment of the present invention.

[0105] One embodiment of the signage display device 1000 may include the LED package 10P, a control unit 20 for controlling the LED package, and an illuminance sensor 30 for detecting external light.

[0106] The LED package 10P may include a first LED group 100 and a second LED group 200. However, this is only illustrative and may include a plurality of various LED groups.

[0107] The first LED group 100 may include a first Red chip 110, a first Green chip 120, and a first Blue chip 130. The second LED group 200 may include a second Red chip 210, a second Green chip 220, and a second Blue chip 230.

[0108] The LED chips included in the first LED group 100 and the second LED group 200 may also include White chips.

[0109] Based on the amount of light detected in the illuminance sensor 30, the control unit 20 can control the mode of the display 1.

[0110] The display device 1000 for signage can include a daytime mode, an HDR mode, and a nighttime mode.

[0111] If the external environment is identified as daytime based on the amount of light detected by the illuminance sensor 30, the control unit 20 can control the sign display device 1000 to daytime mode.

[0112] In the daytime mode of the signage display device 1000, the LED package 10P can drive only the first LED group 100 without driving the second LED group 200.

[0113] If the external environment is identified as a period or season with strong sunlight based on the amount of light detected in the illuminance sensor 30, the control unit 20 can control the LDE package 10P to HDR mode.

[0114] In the HDR mode of the signage display device 1000, the LED package 10P can drive all of the first LED group 100 and the second LED group 200.

[0115] If the external environment is identified as nighttime based on the amount of light detected in the illuminance sensor 30, the control unit 20 can control the sign display device 1000 to nighttime mode.

[0116] In the night mode of the signage display device 1000, the LED package 10P can drive only the second LED group 200 without driving the first LED group 100.

[0117] Because the current range of the second LED group 200 is small, it can display low grayscale with high color depth even at low brightness levels below 300 nits.

[0118] Since the current range of the second LED group 200 is smaller than that of the first LED group 100, it can reduce energy consumption in night mode.

[0119] Furthermore, since the LED groups driven according to their respective modes are different, the current applied to the LED package in each mode can be formed differently.

[0120] This prevents low grayscale from being unlit, color block accumulation, and flickering in night mode.

[0121] Figure 12 This is a graph illustrating the gamma curve of a signage display device with internal technology and the gamma curve of an embodiment of the present invention.

[0122] Figure 12 (a) is a graph showing the gamma curve of the signage display device in night mode. Figure 12 The graph in (b) is a graph showing the gamma curve of a signage display device in night mode according to an embodiment of the present invention.

[0123] It can be observed that in the signage display device of the internal technology, the gamma curve of the White value is uneven and stepped. Due to this phenomenon, there may be unlit areas and color block accumulation at low gray levels.

[0124] Conversely, it can be observed that the gamma curve of the White value in a signage display device according to an embodiment of the present invention has a smooth curve shape.

[0125] Since the signage display device in this embodiment can display the full 14-bit color depth, the low grayscale performance can be rich even in low-brightness night mode.

[0126] This prevents color block accumulation or unlit areas at low gray levels and improves pixel uniformity.

[0127] Figure 13 These are photographs comparing the performance of a signage display device using internal technology with that of a signage display device according to an embodiment of the present invention.

[0128] Figure 13 (a) and Figure 13(b) is a graph showing the grayscale of a signage display device with internal technology and a signage display device according to an embodiment of the present invention in a night mode with a brightness of 300 nits.

[0129] As in Figure 13 As can be observed in (a), the signage display device of the internal technology produces an unlit area of ​​0 to 10 gray, and produces color block accumulation in local areas and problems with pixels not emitting light evenly.

[0130] Figure 13 (b) Since the signage display device, as an embodiment of the present invention, has 14-bit performance, there is no unlit phenomenon in the low grayscale range, and there is no problem of color block accumulation and pixel unevenness.

[0131] The above description focuses on embodiments, but these are merely examples and not intended to limit the invention. Those skilled in the art should understand that various modifications and applications not listed above can be made without departing from the essential characteristics of these embodiments. For example, the specific constituent elements presented in the embodiments can be modified. Furthermore, differences related to these modifications and applications should be interpreted as being included within the scope of the invention as defined by the appended claims.

[0132] [Explanation of reference numerals in the attached figures]

[0133] 1000: Signage display device. 10: LED package.

[0134] 20: Control unit. 30: Illuminance sensor.

[0135] 100: First LED group. 200: Second LED group.

[0136] Industrial applicability

[0137] The display device 1000 of the embodiment can be applied to digital signage. For example, although the display device 1000 of the embodiment is an example of indoor digital signage, the display device 1000 of the embodiment can also be applied to outdoor digital signage.

Claims

1. A display device for signage, wherein, include: Organic light-emitting diode (OLED) package having a plurality of organic light-emitting diode groups; Illuminance sensor, used to detect the illuminance of external light; as well as The control unit controls the organic light-emitting diode package according to the illuminance sensor; Each of the plurality of said organic light-emitting diode groups has a different forward voltage. The control unit drives the organic light-emitting diode package in different modes according to the illuminance sensor.

2. The signage display device according to claim 1, wherein, The organic light-emitting diode (OLED) package includes a first OLED group and a second OLED group. The first OLED group includes a first red light-emitting chip, a first green light-emitting chip, and a first blue light-emitting chip. The second OLED group includes a second red light-emitting chip, a second green light-emitting chip, and a second blue light-emitting chip. The forward voltage of the second organic light-emitting diode group is smaller than that of the first organic light-emitting diode group.

3. The signage display device according to claim 2, wherein, If the illuminance sensor determines that the external environment is daytime, the control unit drives the organic light-emitting diode package in daytime mode. In the daytime mode, the OLED package drives the first OLED group but does not drive the second OLED group.

4. The signage display device according to claim 2, wherein, If the illuminance sensor determines that the external environment requires high-brightness light, the control unit drives the organic light-emitting diode package in a high dynamic range mode. In the high dynamic range mode, the organic light-emitting diode package drives the first organic light-emitting diode group and the second organic light-emitting diode group.

5. The signage display device according to claim 2, wherein, If the illuminance sensor determines that the external environment is nighttime, the control unit drives the organic light-emitting diode package in nighttime mode. In the night mode, the organic light-emitting diode package does not drive the first organic light-emitting diode group, but only drives the second organic light-emitting diode group.

6. A driving method for a signage display device as described in claim 1, wherein, The control unit controls the organic light-emitting diode package to switch between daytime mode, high dynamic range mode, and nighttime mode based on the illuminance sensor. Depending on the mode, the amount of current applied to the organic light-emitting diode package varies.

7. The driving method for the signage display device according to claim 6, wherein, When the control unit drives the organic light-emitting diode package to night mode, the current applied to the organic light-emitting diode package is smaller than the current applied to the organic light-emitting diode package in day mode and high dynamic range mode.

Images