Light-emitting device

Abstract

A light emitting device includes a white light emitting diode. The white light emitting diode emits light during a rising period and a stable period according to a driving current. During the rising period, the brightness of the white light emitting diode increases in a first sequence of steps. The first sequence of steps includes a plurality of sub-rising steps, and the individual time lengths of the plurality of sub-rising steps are less than the time length of the stable period.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting device, and more particularly to a light-emitting device for improving the slow light-emitting response time of red phosphor. Background Art

[0002] At present, white light emitting diodes are used as light sources in some electronic devices. The excitation method of white light emitting diodes includes using a blue light chip to emit blue light to excite green phosphor and red phosphor, so that the blue light, green light and red light are mixed to produce white light. However, due to the slow response time of red phosphor, it is easy to produce the phenomenon that the brightness of the white light emitting diode changes, which initially tends to be cyan (red light appears slowly, but green light and blue light are bright), and finally tends to be red (green light and blue light are dark, but red light disappears slowly). Summary of the invention

[0003] According to an embodiment of the present disclosure, the light emitting device is characterized by comprising a white light emitting diode. The white light emitting diode emits light during a rising period and a stable period according to a driving current. During the rising period, the brightness of the white light emitting diode increases in a first sequence of steps. The first sequence of steps includes a plurality of sub-rising steps, and the individual time lengths of the sub-rising steps are less than the time length of the stable period. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein:

[0005] Figure 1 Schematic diagrams of top and side views of a white light emitting diode according to an embodiment of the present disclosure.

[0006] Figure 2 Schematic diagram of the scene for exciting a white light emitting diode.

[0007] Figure 3 It is a first brightness-time curve diagram of the white light emitting diode according to the embodiment of the present disclosure.

[0008] Figure 4 It is a second brightness-time curve diagram of the white light emitting diode according to the embodiment of the present disclosure.

[0009] Figure 5 Schematic diagram of a top view and a side view of a white light emitting diode according to another embodiment of the present disclosure.

[0010] Figure 6 Schematic diagram of a top view and a side view of a white light emitting diode according to another embodiment of the present disclosure.

[0011] Figure 7This is a third brightness-time curve diagram of the white light emitting diode according to the embodiment of the present disclosure.

[0012] Figure 8 The circuit diagram is a current adjustment circuit for adjusting the driving current of a white light emitting diode according to an embodiment of the present disclosure.

[0013] Explanation of symbols

[0014] 100: White light emitting diode

[0015] 102,B:Blue-ray chip

[0016] 104: Green and red phosphor

[0017] 106: Power cord

[0018] 108: Base

[0019] 200: Display screen

[0020] 202:Object

[0021] 204,206: Area

[0022] A: Observation point

[0023] 210,220,230: Scene

[0024] 300: Blue Light

[0025] 302: Red Light

[0026] 310: During the rise

[0027] 320:Descent

[0028] 330: Stable period

[0029] ΔL: Brightness difference

[0030] ①,②,③,④,⑤,⑥,⑦,⑧: Steps of ascending

[0031] 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 :Sub-step down

[0032] 0,1,2,3,4,5,6: time points

[0033] 400: Blue light

[0034] 402: Red light

[0035] 410: During the rise

[0036] 420:Descent

[0037] 430: Stable period

[0038] 500: White light emitting diode

[0039] 502: Blue light chip

[0040] 504,G: Green light source

[0041] 506,R: Red light source

[0042] 508: Power cord

[0043] 510: Base

[0044] 600: White light emitting diode

[0045] 602: Blue light chip

[0046] 604: Green light source

[0047] 606: Red light source

[0048] 608,612: Power cord

[0049] 610: Base

[0050] 700: Blue Light

[0051] 702: Red Light

[0052] 710: During the rise

[0053] 720:Descent

[0054] 730: Stable period

[0055] 900: Current regulation circuit

[0056] 902: Processor

[0057] 904,DAC: Digital to Analog Converter

[0058] 906: Switch

[0059] 908: Power cord

[0060] 910: White light emitting diode

[0061] VDD: Power supply

[0062] I: driving current DETAILED DESCRIPTION

[0063] In order to make the above-mentioned purposes, features and advantages of some embodiments of the present disclosure more obvious and easy to understand, the following is a detailed description with reference to the attached drawings. In order to make it easier for readers to understand and the drawings are concise, the multiple drawings in the present disclosure may only depict a portion of the entire device, and the specific elements in the drawings are not drawn according to the actual scale.

[0064] It must be understood that certain words are used in this disclosure and the appended claims to refer to specific components. Those skilled in the art will understand that electronic equipment manufacturers may refer to the same components by different names. This document is not intended to distinguish between components that have the same function but different names. The words "comprise", "include" and the like used in this specification and claims are open-ended terms, which are used to indicate the presence of specific technical features, values, method steps, operation processes, components and / or assemblies, but do not exclude the addition of more technical features, values, method steps, operation processes, components, assemblies, or any combination of the above.

[0065] This disclosure specification provides different embodiments to illustrate the technical features of different implementations of the disclosure. Among them, the configuration, quantity and size of each component in the embodiment are for illustrative purposes and are not intended to limit the disclosure. In addition, if the component numbers in the embodiments and the drawings are repeated, it is for the purpose of simplifying the description and does not mean the correlation between different embodiments. Furthermore, the words "first", "second", "third", "fourth" and the like are used to modify the components, not to indicate the priority or prior relationship between them, but to distinguish components with the same name, so that a request component with a certain name can be clearly distinguished from another request component with the same name. The same terms may not be used in the claims, and may be replaced by "first", "second", "third", etc. according to the order in which the components are declared in the claims. Accordingly, the first component in the following description may be the second component in the claims.

[0066] It should also be understood that the directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only referenced to the directions of the accompanying drawings. Therefore, the directional terms used are used to illustrate and are not used to limit the present disclosure. It must be understood that the elements specifically described or illustrated can exist in various forms known to those skilled in the art. In addition, when a layer is "on" other layers or substrates, it may mean "directly" on other layers or substrates, or that a layer is on other layers or substrates, or that other layers are sandwiched between other layers or substrates.

[0067] Figure 1 Schematic diagram of a top view and a side view of a white light emitting diode (LED) according to an embodiment of the present disclosure. Figure 1As shown in the figure, from a side view, the white light emitting diode 100 includes a blue light chip 102, green and red phosphors 104, and a power line 106. The blue light chip 102 emits blue light according to a driving current on the power line 106. The green and red phosphors 104 are excited by the blue light emitted by the blue light chip 102, and are excited to emit green light and red light. Finally, the green light and red light excited by the green and red phosphors 104 are mixed with the blue light emitted by the blue light chip 102, and finally white light is generated. Figure 1 As shown, the blue light chip 102 can be disposed on a base 108, but is not limited thereto. The white light emitting diode 100 of the disclosed embodiment can be applied in an electronic device. The electronic device may include a lighting device, a display device, an antenna device, a sensing device or a splicing device, but is not limited thereto. The electronic device may be a bendable or flexible electronic device. The display device may include, for example, liquid crystal (LC), a light emitting diode, a quantum dot (QD), fluorescence, phosphorescence, or other suitable materials, or a combination of the above materials, but is not limited thereto. The fluorescent material may be a fluoride phosphor, but is not limited thereto. The light emitting diode (LED) may, for example, include an organic light emitting diode (OLED), a sub-millimeter light emitting diode (mini LED), a micro light emitting diode (micro LED) or a quantum dot light emitting diode (quantum dot, QD, which may be, for example, QLED, QDLED). The splicing device may, for example, be a display splicing device or an antenna splicing device, but is not limited thereto. It should be noted that the electronic device can be any combination of the above, but is not limited thereto. The following will illustrate the content of the present disclosure with a display device having a backlight source, but the present disclosure is not limited thereto.

[0068] Figure 2 Schematic diagram of the scene for exciting a white light emitting diode. Figure 2 Included are scenes 210, 220, and 230. In some embodiments, scenes 210, 220, and 230 are arranged in a time sequence. In scenes 210, 220, and 230, an object 202 moves from the left side of the display screen 200 (scene 210) to the middle of the display screen 200 (scene 220), and then moves from the middle of the display screen 200 to the right side of the display screen 200 (scene 230). In some embodiments, the backlight source of the area where the object 202 is located in the display screen 200 lights up accordingly as the object 202 moves. In some embodiments, the backlight source in the area where the object 202 is located is in an on state, while the backlight source in the area outside the object 202 in the display screen 200 is in an off state. It should be noted that Figure 2The embodiment may correspond to a local dimming technology of a liquid crystal display device, but the present disclosure is not limited thereto.

[0069] Taking observation point A on the display screen 200 as an example, in the scene 210, when the object 202 starts to move from the leftmost side of the display screen 200, when the front end of the object 202 moves rightward to the observation point A, the backlight source (e.g. Figure 1 When the white light emitting diode (LED) is just turned on, the red phosphor reacts more slowly, so it can be observed that the observation point A is biased towards cyan. More specifically, since the red phosphor reacts more slowly, the green light and blue light in the backlight source corresponding to the observation point A reach the target brightness faster, but the red light has not yet reached the target brightness, so the image at the observation point A is biased towards cyan. In scene 220, the object 202 continues to move to the right side of the display screen 200, so that the observation point A is roughly located in the middle of the object 202. In scene 220, the backlight source corresponding to the observation point A has been fully turned on (that is, the green light, blue light, and red light have all reached the target brightness and entered a stable state), so it can be observed that the observation point A presents white light. Next, in scene 230, when the object 202 continues to move to the right side of the display screen 200 and gradually moves away from the observation point A, the backlight source corresponding to the observation point A has been turned off, but because the red phosphor reacts more slowly, it can be observed that the observation point A is biased towards red. More specifically, at this time, the driving current of the backlight source corresponding to the observation point A has been turned off, and the brightness of the blue light and green light in the backlight source corresponding to the area quickly drops to the dark state brightness after the light source is turned off, but because the red phosphor reacts more slowly, the red light has not yet dropped to the dark state brightness, resulting in the image presented at the observation point A being biased towards red. The following will explain how to adjust the driving method of the light emitting diode to improve this phenomenon.

[0070] Figure 3 It is a first brightness-time curve diagram of the white light emitting diode according to the embodiment of the present disclosure. Figure 3 A comparison diagram of the brightness of cyan light (in this disclosure, it refers to the color light formed by mixing green light and blue light) and red light emitted from the white light emitting diode 100 during the period from time point 1 to time point 6 is disclosed.

[0071] like Figure 3 As shown, during the process of turning on and off the blue light 300 and the red light 302, the brightness changes include a rising period 310, a stable period 330, and a falling period 320. Figure 1 and Figure 3When the white light emitting diode 100 is turned on at time point 1 according to a driving current from the power line 106, in order to solve the problem of the slow response speed of the red phosphor, the present disclosure first determines whether the absolute value of the difference between the brightness of the white light emitting diode 100 at time point 1 and the brightness of the white light emitting diode 100 at time point 2 is greater than a first threshold value.

[0072] Please refer to Figures 1 to 3 . In the present disclosure, when the absolute value of the difference is greater than the first threshold, the action of dividing the period from time point 1 to time point 2 into a sequence of steps is initiated, wherein the sequence of steps includes a plurality of sub-rising steps, and the brightness of the white light emitting diode increases with the sequence of steps. When the absolute value of the difference is not greater than the first threshold, the action of dividing the period from time point 1 to time point 2 into a plurality of sub-rising steps will not be performed. In some embodiments, the period between time point 1 and time point 2, the period between time point 2 and time point 3, or the period between time point 3 and time point 4 may represent a frame of the display screen 200 where the white light emitting diode 100 is located. In some embodiments, the display screen 200 generates a frame at a clock frequency of 60 Hz, but the present disclosure is not limited thereto. In some embodiments, such as Figure 3 As shown, the present disclosure divides the rising period 310 into 8 sub-rising steps, such as sub-rising steps ① to ⑧. In some embodiments, the sub-rising steps can be generated by increasing the clock frequency, but the present disclosure is not limited to this. For example, in the present embodiment, sub-rising steps ① to ⑧ are generated at a clock frequency of 480 Hz (60 Hz*8). In some embodiments, the individual time lengths of sub-rising steps ① to ⑧ are less than the time length of the stable period 330, and the individual time lengths of sub-rising steps ① to ⑧ may be the same. In some embodiments, the present disclosure adjusts the magnitude of the driving current received by the white light emitting diode 100 so that the brightness of the blue light 300 and the red light 302 gradually increases in sub-rising steps ① to ⑧. In other words, in sub-rising steps ① to ⑧, the driving current received by the white light emitting diode 100 gradually increases with the sub-rising steps ① to ⑧.

[0073] For example, if Figure 3As shown, the brightness difference between the cyan light 300 and the red light 302 before turning on (for example, before time point 1) and during the stable period 330 (for example, during the period from time point 2 to time point 5) is ΔL. Therefore, in the sub-rising step ①, the brightness increase of the cyan light 300 is (ΔL / 8), and at the end of the sub-rising step ①, the brightness increase of the red light 302 is also (ΔL / 8). In the sub-rising step ②, the total brightness increase of the cyan light 300 is 2*(ΔL / 8), and at the end of the sub-rising step ②, the total brightness increase of the red light 302 is also 2*(ΔL / 8). In the sub-rising step ③, the total brightness increase of the cyan light 300 is 3*(ΔL / 8), and at the end of the sub-rising step ③, the total brightness increase of the red light 302 is also 3*(ΔL / 8). By analogy, at the sub-rising step ⑧, the total increase in brightness of the blue light 300 is 8*(ΔL / 8), and at the end of the sub-rising step ⑧, the total increase in brightness of the red light 302 is also 8*(ΔL / 8).

[0074] Since the red phosphor reacts slowly, the brightness of the red light 302 is different from that of the cyan light 300 in other time periods (e.g., in the middle of individual time periods of sub-rising steps ① to ⑧) except at the end of the sub-rising steps ① to ⑧. That is, in the middle of the time length of individual sub-rising steps, the brightness of the red light 302 is different from that of the cyan light 300, but at the end of the time length of individual sub-rising steps, the brightness of the red light 302 is the same as that of the cyan light 300, as shown in FIG. Figure 3 However, the present disclosure is not limited thereto.

[0075] Based on the above relationship, the brightness of each sub-rising step can be obtained by the following formula 1.

[0076]

[0077] Where z is the number of sub-ascending steps; F(n z ) is the nth z f(n) is the brightness at time point n; f(n-1) is the brightness at time point n-1. Figure 3 If we want to use the above formula to find the brightness of the blue light 300 at the sub-upward step ⑤, we can substitute f(n)=ΔL, f(n-1)=0, z=8, n z =5 to formula 1, and the brightness of the blue light 300 at the sub-upward step ⑤ is obtained as F(n z )=5*(ΔL / 8).

[0078] Similarly, refer to Figure 1 and Figure 3, when the white light emitting diode 100 gradually dims at time point 5 according to the driving current from the power line 106, in order to solve the problem of the slow reaction speed of the red phosphor, the present disclosure first determines whether the absolute value of the difference between the brightness of the white light emitting diode 100 at time point 5 and the brightness of the white light emitting diode 100 at time point 6 is greater than a second threshold. When the absolute value of the difference is greater than the second threshold, the present disclosure will initiate the action of dividing the period from time point 5 to time point 6 into a sequence of steps, wherein the sequence of steps includes a plurality of sub-decreasing steps. When the absolute value of the difference is not greater than the second threshold, the technical solution of the present disclosure will not perform the action of dividing the period from time point 5 to time point 6 into a plurality of sub-decreasing steps. In some embodiments, such as Figure 3 As shown, the present disclosure divides the descending period 320 into 8 sub-decreasing steps, such as the sub-decreasing steps 1 ~ 8 , but the present disclosure is not limited thereto. In some embodiments, the sub-down steps can be generated by increasing the clock frequency. For example, in this embodiment, the sub-down steps are generated at a clock frequency of 480 Hz (60 Hz*8). 1 ~ 8 In some embodiments, the sub-step 1 ~ 8 The individual time length of the sub-step is less than the time length of the stable period 330, and the sub-step 1 ~ 8 In some embodiments, the present disclosure adjusts the driving current received by the white light emitting diode 100 so that the brightness of the blue light 300 and the red light 302 decreases in the sub-steps. 1 ~ 8 In other words, in the descending step 1 ~ 8 In the embodiment, the driving current received by the white light emitting diode 100 decreases with the step-down 1 ~ 8 In some embodiments, the second threshold value may be the same as or different from the first threshold value.

[0079] For example, if Figure 3 As shown, the brightness difference between the cyan light 300 and the red light 302 during the stable period 330 (e.g., during the period from time point 2 to time point 5) and after the light is turned off is ΔL. 1 When the brightness of the blue light 300 is ΔL-(ΔL / 8), 1 At the end of the step, the brightness of the red light 302 is also ΔL-(ΔL / 8). 2 When the brightness of the blue light 300 is ΔL-2*(ΔL / 8), 2At the end of the step, the brightness of the red light 302 is also ΔL-2*(ΔL / 8). 3 When the brightness of the blue light 300 is ΔL-3*(ΔL / 8), 3 At the end of the step, the brightness of the red light 302 is also ΔL-3*(ΔL / 8). 8 When the brightness of the blue light 300 is ΔL-8*(ΔL / 8)=0, 8 At the end of the process, the brightness of the red light 302 is also 0.

[0080] Since the red phosphor reacts slowly, the brightness of the red light 302 decreases in the sub-steps. 1 ~ 8 Other periods except the end of the 1 ~ 8 That is, in the middle of the time length of the individual sub-down step, the brightness of the red light 302 is different from the brightness of the blue light 300, but at the end of the time length of the individual sub-down step, the brightness of the red light 302 is the same as the brightness of the blue light 300, such as Figure 3 However, the present disclosure is not limited thereto. 1 ~ 8 In the present disclosure, the above formula 1 can also be used to obtain the brightness of each sub-step. Figure 3 , if we want to use the above formula to find the descending step 6 The brightness of the blue light is 300, so we substitute f(n)=0, f(n-1)=ΔL, z=8, n z =6 to formula 1, and find the descending step in the sub 6 When the brightness of the blue light 300 is F(n z )=ΔL-6*(ΔL / 8).

[0081] In some embodiments, during the rising period 310 and the falling period 320, the driving current for driving the cyan light 300 (or the red light 302) is proportional to the magnitude of the sub-rising steps ① to ⑧ and the sub-falling steps. 1 ~ 8The brightness of the individual cyan light 300 (or red light 302) is proportional to the brightness of the individual cyan light 300 (or red light 302), so in these embodiments, when the brightness increase of each sub-rising step is the same, the driving current increase of the sub-rising step is also the same. Similarly, when the brightness reduction of each sub-rising step is the same, the driving current reduction of the sub-decreasing step is also the same. For example, the driving current of the cyan light 300 and the red light 302 during the stable period 330 is X mA. Therefore, in sub-rising step ③, the driving current of the cyan light 300 and the red light 302 is 3*(X / 8)mA; in sub-rising step ⑥, the driving current of the cyan light 300 and the red light 302 is 6*(X / 8)mA; in the descending step 2 When the driving current of the blue light 300 and the red light 302 is X-2*(X / 8)mA; and in the descending step 7 When , the driving current of the cyan light 300 and the red light 302 is X-7*(X / 8), and so on.

[0082] Based on the above relationship, the driving currents of the cyan light 300 and the red light 302 in the sub-rising step or the sub-falling step can be obtained by the following formula 2.

[0083]

[0084] Where z is the number of sub-ascending steps or descending steps; I(n z ) is the driving current at the zth sub-upward or downward step; i(n) is the driving current at time point n; i(n-1) is the driving current at time point n-1. Figure 3 If the driving current of the blue light 300 in the sub-upper step ⑤ is to be obtained by the above formula 2, then i(n)=X, i(n-1)=0, z=8, n z =5 to equation 2, and the driving current of the blue light 300 in the sub-rising step ⑤ is obtained as I(n z )=5*(X / 8). Similarly, if we want to use the above formula 2 to find the descending step in the child 6 When the driving current of the blue light 300 is 0, then substitute i(n)=0, i(n-1)=X, z=8, n z =6 to equation 2, and find the descending step in the child 6 When the driving current of Qingguang 300 is I(n z )=X-6*(X / 8). It should be noted that, in some embodiments, although the brightness of the light source increases with the increase of the current, it is not necessarily proportional. However, in these embodiments, it can still be determined that during the rising period 310, the driving current will still gradually increase along each sub-rising step. Similarly, during the falling period 320, the driving current will still gradually decrease along each sub-falling step.

[0085] The present disclosure divides the rising period 310 into a plurality of rising sub-steps (e.g., rising sub-steps ① to ⑧), and divides the falling period 320 into a plurality of falling sub-steps (e.g., falling sub-steps ① to ⑧). 1 ~ 8 ), so that the brightness of the blue light 300 during the rising period 310 and the falling period 320 can be close to (or substantially equal to) the brightness of the red light 302, so as to reduce Figure 2 The problem in scenes 210 and 230 is caused by the slow reaction speed of the red phosphor.

[0086] In some embodiments, the present disclosure adjusts the driving current received by the white light emitting diode 100 so that the brightness of the blue light 300 and the red light 302 increases nonlinearly in the sub-rising steps ① to ⑧. For example, in the sub-rising steps ① to ⑧, the driving current received by the white light emitting diode 100 increases exponentially with the sub-rising steps ① to ⑧.

[0087] Figure 4 It is a second brightness-time curve diagram of the white light emitting diode according to the embodiment of the present disclosure. Figure 4 The figure shows a comparison of the brightness of the blue light 400 and the red light 402 emitted by the white light emitting diode 100 from time point 1 to time point 6. Figure 4 As shown, during the process of turning on and off the blue light 400 and the red light 402, the brightness changes include a rising period 410, a stable period 430, and a falling period 420. Figure 1 and Figure 4 When the white light emitting diode 100 is turned on at time point 1 according to a driving current from the power line 106, in order to solve the problem of the slow response speed of the red phosphor, the present disclosure first determines whether the absolute value of the difference between the brightness of the white light emitting diode 100 at time point 1 and the brightness of the white light emitting diode 100 at time point 2 is greater than a third threshold.

[0088] When the absolute value of the difference is greater than the third threshold, the present disclosure initiates the action of dividing the period from time point 1 to time point 2 into a plurality of sub-increase steps. When the absolute value of the difference is not greater than the third threshold, the present disclosure does not perform the action of dividing the period from time point 1 to time point 2 into a plurality of sub-increase steps. Figure 4As shown, the present disclosure divides the rising period 410 into 8 sub-rising steps, such as sub-rising steps ① to ⑧, but the present disclosure is not limited thereto. In some embodiments, the individual time lengths of the sub-rising steps ① to ⑧ are less than the time length of the stable period 430. In some embodiments, the present disclosure adjusts the magnitude of the driving current received by the white light emitting diode 100 so that the brightness of the cyan light 400 and the red light 402 increases nonlinearly (for example, it may be an exponential increase) in the sub-rising steps ① to ⑧. In other words, in the sub-rising steps ① to ⑧, the driving current received by the white light emitting diode 100 increases nonlinearly with the sub-rising steps ① to ⑧.

[0089] For example, if Figure 4 As shown, the brightness difference between the cyan light 400 and the red light 402 before turning on (e.g., before time point 1) and during the stable period 430 (e.g., during the period from time point 2 to time point 5) is ΔL, and the brightness difference between the stable period 430 and after the cyan light 400 and the red light 402 are turned off (e.g., after time point 6) is also ΔL. Therefore, in the sub-rising step ①, the brightness of the cyan light 400 is (ΔL / 2), and at the end of the sub-rising step ①, the brightness of the red light 402 is also ΔL / 2. In the sub-rising step ②, the brightness of the cyan light 400 is (ΔL / 2)+(ΔL / 4)=(3*ΔL / 4), and at the end of the sub-rising step ②, the brightness of the red light 402 is also (3*ΔL / 4). In sub-rising step ③, the brightness of the blue light 400 is (ΔL / 2)+(ΔL / 4)+(ΔL / 8)=(7*ΔL / 8). At the end of sub-rising step ③, the brightness of the red light 402 is also (7*ΔL / 8), and so on.

[0090] According to the above relationship, when the brightness changes exponentially, the brightness of each sub-rising step can be obtained by, for example, the following formula 3.

[0091]

[0092] Where z is the number of sub-ascending steps; F(n z ) is the nth z f(n) is the brightness at time point n; f(n-1) is the brightness at time point n-1. Figure 4 If we want to use the above formula 3 to find the brightness of the blue light 400 at the sub-upper step ⑤, we can substitute f(n)=ΔL, f(n-1)=0, z=8, n z =5 to formula 3, and the brightness of the blue light 400 at the sub-upward step ⑤ is obtained as F(n z )=(ΔL / 2)+(ΔL / 4)+(ΔL / 8)+(ΔL / 16)+(ΔL / 32)=(31*ΔL / 32).

[0093] Similarly, refer to Figure 1 and Figure 4 , when the white light emitting diode 100 is gradually turned off at time point 5 according to the driving current from the power line 106, in order to solve the problem of the slow reaction speed of the red phosphor, the present disclosure first determines whether the absolute value of the difference between the brightness of the white light emitting diode 100 at time point 5 and the brightness of the white light emitting diode 100 at time point 6 is greater than a fourth threshold. When the absolute value of the difference is greater than the fourth threshold, the present disclosure starts the action of dividing the period from time point 5 to time point 6 into multiple sub-decreasing steps. When the absolute value of the difference is not greater than the fourth threshold, the present disclosure turns off the action of dividing the period from time point 5 to time point 6 into multiple sub-decreasing steps. In some embodiments, as Figure 4 As shown, the present disclosure divides the descending period 420 into 8 descending sub-steps, such as the descending sub-steps. 1 ~ 8 In some embodiments, the sub-rising step can be generated by increasing the clock frequency. For example, in this embodiment, the sub-falling step is generated by using a clock frequency of 480 Hz (60 Hz*8). 1 ~ 8 In some embodiments, the sub-step 1 ~ 8 The individual time length of the stable period 430 is less than the time length of the stable period 430, and the sub-decreasing step 1 ~ 8 In some embodiments, the present disclosure adjusts the driving current received by the white light emitting diode 100 so that the brightness of the blue light 400 and the red light 402 decreases in sub-steps. 1 ~ 8 For example, in the descending step 1 ~ 8 In the embodiment, the driving current received by the white light emitting diode 100 decreases with the step-down 1 ~ 8 In some embodiments, the third threshold value may be the same as or different from the fourth threshold value.

[0094] In the descending step 1 ~ 8 In the present disclosure, the above formula 3 can also be used to obtain the brightness of each sub-down step. 3 The brightness of the blue light is 400, so we substitute f(n)=0, f(n-1)=ΔL, z=8, n z =3 to equation 3, and find the descending step in the child 3 When the brightness of the blue light 400 is F(n z)=ΔL-[(ΔL / 2)+(ΔL / 4)+(ΔL / 8)]=(ΔL / 8).

[0095] It should be noted that according to Formula 3, at the end of the last step of the sub-rising step or the sub-decreasing step (eg, rising step ⑧ or sub-decreasing step 8), there may still be some difference from the brightness of the stable state. Figure 4 In the embodiment, when the sub-rising step ⑧ ends, according to Formula 3, its brightness should be F(8)=(ΔL / 2)+(ΔL / 4)+…+(ΔL / 256)=255*ΔL / 256(≠ΔL).

[0096] In order to compensate for this difference, in some embodiments, compensation is forced to be performed in the last step (for example, the current increase is increased in the last rising sub-step to exceed the current increase corresponding to the brightness difference originally obtained according to Formula 3, or the current decrease is increased in the last falling sub-step to exceed the current decrease corresponding to the brightness difference originally obtained according to Formula 3), so that in all son The brightness at the end of an ascending step or all descending sub-steps can be compared with the stabilization period (e.g. Figure 4 The brightness is the same during the stable period 430 or after time point 6).

[0097] In some embodiments, during the rising period 410 and the falling period 420, the driving current for driving the cyan light 400 (or the red light 402) is proportional to the magnitude of the sub-rising steps ① to ⑧ and the sub-falling steps. 1 ~ 8 The brightness of the individual cyan light 400 (or red light 402) is proportional to the brightness of the individual cyan light 400 (or red light 402). For example, the driving current of the cyan light 400 and the red light 402 during the stable period 430 is Y mA. Therefore, in the sub-rising step ③, the driving current of the cyan light 400 and the red light 402 is (Y / 2)+(Y / 4)+(Y / 8)=(7*Y / 8)mA; in the sub-rising step ⑥, the driving current of the cyan light 400 and the red light 402 is (Y / 2)+(Y / 4)+(Y / 8)+(Y / 16)+(Y / 32)+(Y / 64)=(63*Y / 64)mA; in the descending step 2 When the driving current of the cyan light 400 and the red light 402 is Y-[(Y / 2)+(Y / 4)]=(Y / 4)mA; and in the descending step 7 When , the driving current of the cyan light 400 and the red light 402 is Y-[(Y / 2)+(Y / 4)+…+(Y / 128)]=(Y / 128)mA, and so on.

[0098] According to the above relationship, the driving current magnitudes of the cyan light 400 and the red light 402 in the sub-rising step or the sub-falling step can be obtained by the following formula 4.

[0099]

[0100] Where z is the number of sub-ascending steps or descending steps; I(n z ) is the nth z i(n) is the driving current at time point n; i(n-1) is the driving current at time point n-1. Figure 4 If the driving current of the blue light 400 in the sub-up step ⑤ is to be obtained by the above formula 4, then i(n)=Y, i(n-1)=0, z=8, n z =5 to equation 4, and the driving current of the blue light 400 in the sub-rising step ⑤ is obtained as I(n z )=(31*Y / 32). Similarly, if we want to use the above formula 4 to find the descending step in the child 6 When the driving current of the blue light 400 is 0, then substitute i(n)=0, i(n-1)=Y, z=8, n z =6 to equation 4, and find the descending step in the child 6 When the driving current of Qingguang 400 is I(n z )=(Y / 64). It should be noted that in some embodiments, compensation is performed in the last step so that son The brightness at the end of an ascending step or all descending sub-steps can be compared with the stabilization period (e.g. Figure 4 Therefore, the current after compensation directly corresponds to the current during the stable period, rather than being calculated using Formula 4.

[0101] exist Figure 4 During the rising period 410, due to the slow reaction speed of the red phosphor, the brightness of the red light 402 is different from the brightness of the cyan light 400 in other periods (e.g., in the middle of each period of the sub-rising steps ① to ⑧) except the end of the sub-rising steps ① to ⑧. Figure 4 As shown, the brightness of the red light 402 is lower than the brightness of the blue light 400 in the other periods except the end of the sub-rising steps ① to ⑧, but the present disclosure is not limited thereto. Figure 4 During the falling period 420, the brightness of the red light 402 decreases in the sub-decreasing step due to the slow reaction speed of the red phosphor. 1 ~ 8 Other periods except the end of the 1 ~ 8 The brightness of the blue light 400 is different from that of the middle of the individual time period. Figure 4 As shown, the brightness of the red light 402 decreases in sub-steps. 1 ~ 8The brightness of the other time periods except the end is higher than that of the blue light 400, but the present disclosure is not limited to this.

[0102] The present disclosure divides the rising period 410 into a plurality of rising sub-steps (e.g., rising sub-steps ① to ⑧), and divides the falling period 420 into a plurality of falling sub-steps (e.g., falling sub-steps ① to ⑧). 1 ~ 8 ), so that the brightness of the blue light 400 during the rising period 410 and the falling period 420 can be close to (or substantially equal to) the brightness of the red light 402, so as to eliminate Figure 2 The problem in scenes 210 and 230 is caused by the slow reaction speed of the red phosphor.

[0103] Figure 5 Schematic diagram of a top view and a side view of a white light emitting diode according to another embodiment of the present disclosure. Figure 5 As shown, from a side view, the white light emitting diode 500 includes a plurality of sub-units such as a blue light chip 502, a green light source 504, and a red light source 506, and a power line 508. The blue light chip 502 emits blue light according to a driving current on the power line 508. The green light source 504 and the red light source 506 can be composed of two other blue light chips 502 combined with green phosphor and red phosphor respectively. Finally, the green light and red light emitted by the green light source 504 and the red light source 506 are mixed with the blue light emitted by the blue light chip 502 to finally generate white light. Figure 5 As shown, the blue light chip 502, the green light source 504, and the red light source 506 are arranged on a base 510, but the arrangement of the light source in the present disclosure is not limited thereto. In some embodiments, the blue light chip 502, the green light source 504, and the red light source 506 are connected to the power line 508. Therefore, the driving current received by the blue light chip 502, the green light source 504, and the red light source 506 is the same.

[0104] In some embodiments, Figure 5 The brightness-time curve of the white light emitting diode 500 is Figure 1 The brightness-time curve of the white light emitting diode 100 is the same or similar, for example Figure 3 or Figure 4 The brightness-time curve diagram is not shown in detail, so it will not be repeated here.

[0105] In some embodiments, Figure 5 The brightness-time curve of the white light LED500 is Figure 1 The brightness-time curve of the white light LED 100 is the same as that of Figure 3 and Figure 4 The brightness-time curve diagram is not shown in detail, so it will not be repeated here.

[0106] Figure 6 Schematic diagram of a top view and a side view of a white light emitting diode according to another embodiment of the present disclosure. Figure 6 As shown, from a side view, the white light emitting diode 600 includes a plurality of sub-units such as a blue light chip 602, a green light source 604, a red light source 606, and a power line 608 and a power line 612. The blue light chip 602 and the green light source 604 emit blue light and green light according to a first driving current on the power line 608. The red light source 606 emits red light according to a second driving current on the power line 612. The green light source 604 and the red light source 606 can be composed of two other blue light chips 602 combined with green phosphor and red phosphor, respectively. As described above, the green light and red light emitted by the green light source 604 and the red light source 606 when excited are mixed with the blue light emitted by the blue light chip 602 to finally generate white light. As shown Figure 6 As shown, the blue light chip 602, the green light source 604, and the red light source 606 are disposed on a base 610, but are not limited thereto. In some embodiments, the blue light chip 602 and the green light source 604 are connected to the power line 608, but the red light source 606 is independently connected to the power line 612. Therefore, the driving current of the blue light chip 602 and the green light source 604 is the same, but the driving current received by the red light source 606 may be the same as or different from the driving current of the blue light chip 602 and the green light source 604.

[0107] In some embodiments, the present disclosure only controls the driving current flowing through the power line 608, but does not control the driving current flowing through the power line 612. In some embodiments, the present disclosure controls the driving current flowing through both the power line 608 and the power line 612, but in different control methods. Figure 7 For the present disclosure of the embodiment Figure 6 The first brightness-time curve of the white light emitting diode. Figure 7 The figure shows a comparison of the brightness of the blue light 700 and the red light 702 emitted by the white light emitting diode 600 from time point 1 to time point 6. Figure 7 As shown, during the process of turning on and off the blue light 700 and the red light 702, the brightness changes include a rising period 710, a stable period 730, and a falling period 720. Figure 6 The red light source 606 of the white light emitting diode 600 is independently connected to the power line 612, so Figure 7The brightness of the red light 702 may not increase in a sub-upward step manner or decrease in a sub-downward step manner. More specifically, the control method of the driving current of the red light source 606 is different from the control method of the driving current of the blue light chip 602 and the green light source 604, so that the brightness change of the red light 702 during the rising period 710 and the falling period 720 each presents a complete single curve, but the control method of the driving current of the red light source 606 in the present disclosure is not limited to the method of presenting a single curve change.

[0108] Figure 7 The brightness change curve of Qingguang 700 is Figure 3 The brightness change curve of the blue light 300 is the same or similar. In some embodiments, the present disclosure can still use the above formula 1 to obtain the individual brightness of the blue light 700 in the 8 sub-rising steps during the rising period 710, and the individual brightness of the blue light 700 in the 8 sub-decreasing steps during the falling period 720. The present disclosure can also use the above formula 2 to obtain the individual driving current of the blue light 700 in the 8 sub-rising steps during the rising period 710, and the individual driving current of the blue light 700 in the 8 sub-decreasing steps during the falling period 720, so it will not be repeated. In addition, the driving current can also be adjusted to make Figure 7 The brightness change of Zhongqingguang 700 Figure 4 The brightness variation curve of the blue light 400 is the same or similar. However, the control method for the driving current of the blue light chip 602 and the green light source 604 in the present disclosure is not limited to this.

[0109] Figure 8 FIG. 1 is a circuit diagram of a current regulating circuit for regulating the driving current of a white light emitting diode according to an embodiment of the present disclosure. Figure 8 As shown, the current adjustment circuit 900 includes a processor 902, a digital-to-analog converter (DAC) 904, a switch 906, and a power line 908. In some embodiments, the processor 902 obtains the driving current information of the white light emitting diode 910 at each time point (e.g., each frame) from a current detector (not shown), and brings the driving current information into the above formula 2 and formula 4 to calculate the driving current at the corresponding sub-rising step or sub-decreasing step. Then, the processor 902 converts the driving current calculation results of the above formula 2 and formula 4 into a corresponding digital signal, and inputs the digital signal to the digital-to-analog converter 904. In some embodiments, the processor 902 obtains the brightness information of the white light emitting diode 910 at each time point (e.g., each frame) from a brightness detector (not shown) as a basis for whether to start dividing into multiple sub-rising steps or multiple sub-decreasing steps.

[0110] In some embodiments, the processor 902 may be a processor in a display or a processor in a host connected to the display, but is not limited thereto. Next, the digital-to-analog converter 904 converts the digital signal corresponding to the driving current calculation result into a voltage signal V i , and the output voltage signal V i To switch 906. Switch 906 is switched according to the voltage signal V i The voltage level of the switch 906 is adjusted accordingly, and the magnitude of a driving current I flowing from the power source VDD through the switch 906 and finally flowing to a white light emitting diode 910 through the power line 908 is adjusted accordingly. In some embodiments, the switch 906 may be, but is not limited to, an N-type field effect transistor. When the switch 906 is an N-type field effect transistor, the higher the voltage signal received by the gate, the larger the channel between the drain and the source of the switch 906 (the switch 906 operates in the linear region of the transistor IV curve), so that the driving current I flowing to the white light emitting diode 910 can be adjusted accordingly.

[0111] In some embodiments, Figure 8 The power line 908 corresponds to Figure 1 Power cord 106 or Figure 5 The power cord 508. Figure 8 The white light emitting diode 910 may be Figure 1 White light emitting diodes 100 or Figure 5 The white light emitting diode 500. Figure 6 In the embodiment shown, the power line 608 and the power line 612 can be controlled by two different switches 906 (the second switch 906 is not shown), and the driving current I flowing through the two power lines can be controlled individually by adjusting the voltage received by the gate of the switch 906. However, the current adjustment circuit architecture disclosed in the present invention is not limited thereto.

[0112] Although the embodiments of the present invention are described above, it should be understood that what is presented above is only an example and not a limitation. Many changes to the above exemplary embodiments can be implemented without violating the spirit and scope of the invention according to this embodiment. Therefore, the breadth and scope of the present invention should not be limited by the embodiments described above. Rather, the scope of the present invention should be defined by the claims and their equivalents. Although the above invention has been illustrated and described by one or more related executions, equivalent changes and modifications will be thought of by others who are familiar with this field based on the above specifications and drawings. In addition, although a particular feature of the present invention has been demonstrated by one of the related multiple executions, the above feature may be combined with one or more other features so that there may be a need and help for any known or special application.

[0113] The professional terms used in this specification are only for the purpose of describing specific embodiments and are not intended to be used as limitations of the present invention. Unless the context clearly indicates otherwise, the singular, one, the above and the above-mentioned meanings used herein also include the plural. Furthermore, the words "include", "comprise", "have", "have", or their variations are either used as detailed descriptions or as claims. The above-mentioned words mean to include and are equivalent to the word "include" to a certain extent. Unless there are different definitions, all the words used in this article (including technical or scientific terms) can be generally understood by ordinary technicians in the technical field of the above-mentioned invention. We should be more aware that the above-mentioned words, such as those defined in commonly used dictionaries, should be interpreted as the same meaning in the context of the relevant technology. Unless explicitly defined in this article, the above-mentioned words will not be interpreted as idealized or overly formal.

Claims

1. A light emitting device, characterized in that: Include: A white light emitting diode emits light during a rising period and a stable period according to a driving current; wherein during the rising period, the brightness of the white light emitting diode increases in a first sequence of steps, the first sequence of steps comprising a plurality of sub-rising steps, and the individual time lengths of the plurality of sub-rising steps are less than the time length of the stable period; The white light emitting diode comprises a first subunit emitting a first color light and a second subunit emitting a second color light; wherein, in the middle of the time length of at least one of the plurality of sub-rising steps, the brightness of the first color light is different from the brightness of the second color light, and at the end of the time length of the at least one of the plurality of sub-rising steps, the brightness of the first color light is the same as the brightness of the second color light, wherein the first color light is cyan light and the second color light is red light; wherein the brightness of the first color light increases in a manner different from the brightness of the second color light; and The increase of the driving current in the plurality of sub-rising steps is nonlinear.

2. The light emitting device according to claim 1, characterized in that: During the rising period, the driving current of the white light emitting diode gradually increases.

3. The light emitting device according to claim 1, characterized in that: The respective time lengths of the plurality of ascending sub-steps are the same.

4. The light emitting device according to claim 1, characterized in that: The white light emitting diode gradually dims during a falling period according to the driving current, and during the falling period, the brightness of the white light emitting diode decreases step by step with a second sequence.

5. The light emitting device according to claim 4, characterized in that: The second sequence of steps includes a plurality of sub-decreasing steps, and respective time lengths of the plurality of sub-decreasing steps are shorter than a time length of the stable period.

6. The light emitting device according to claim 5, characterized in that: The respective time lengths of the plurality of descending sub-steps are the same.

7. The light emitting device according to claim 5, characterized in that: The reduction of the driving current in the plurality of sub-down steps is non-linear.

8. The light emitting device according to claim 5, characterized in that: The white light emitting diode includes a first subunit emitting the first color light and a second subunit emitting the second color light; wherein, in the middle of the time length of at least one of the multiple sub-decreasing steps, the brightness of the first color light is different from the brightness of the second color light, and at the end of the time length of at least one of the multiple sub-decreasing steps, the brightness of the first color light is the same as the brightness of the second color light.

Images