LED driving system and method
By designing an LED driving system including conversion circuit, driving circuit and control circuit, the problem of difficulty in realizing high-precision brightness adjustment in the prior art is solved, and high-precision adjustment of LED brightness and richer image effects are achieved.
Patent Information
- Application Number
- CN202280098458.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-01
- Publication Date
- 2025-04-15
AI Technical Summary
It is difficult for existing LED driver systems to achieve high-precision brightness adjustment, especially when the grayscale level needs to be fine-tuned, and better display effects cannot be obtained.
By designing an LED driving system including a conversion circuit, a driving circuit and a control circuit, the conversion circuit converts the first voltage input into a second voltage having a voltage difference, the driving circuit generates an output signal based on the second voltage, and the control circuit controls the brightness of the LED based on the output signal.
High-precision adjustment of LED brightness is achieved, significantly improving the fineness of the display, and the brightness can be adjusted in 256 levels, 1024 levels or 4096 levels, thereby achieving richer and more refined image effects.
Smart Images
Figure CN119836655A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates generally to display technology, and more particularly, to LED driving systems and methods. Background Art
[0002] The grayscale of LED displays mainly determines the gray level of brightness used to display content such as pictures and video images. Brightness is a measurable quality of light that corresponds to brightness. The brightness of each LED pixel is adjustable, and the fineness of the adjustment is the grayscale of the display. The higher the grayscale, that is, the higher the number of brightness levels, the more refined and colorful the displayed image will be.
[0003] A light-emitting unit includes red, green and blue LEDs and a driving circuit. A driving chip generally used to provide the driving circuit includes a chip with a built-in serial-parallel shift register unit and an output latch unit. The control input signal of the driving chip includes data (R, G, B), a shift pulse (for example, provided by a clock (CLK)), a latch pulse (for example, provided by a strobe), etc.
[0004] Typically, a linear adjustment scheme for LED current is used to change its brightness. A method for adjusting the LED grayscale by adjusting the number of pulses is also disclosed. However, the grayscale level needs to be fine-tuned to obtain a better display effect. Summary of the invention
[0005] The embodiment of the present disclosure provides an LED driving system, which includes: a conversion circuit configured to convert a first voltage into a second voltage based on a control input, wherein the second voltage has a voltage difference relative to the first voltage; a driving circuit coupled to the conversion circuit to receive the second voltage and configured to generate an output signal based on the second voltage; and a control circuit coupled to the driving circuit and configured to control the brightness of an LED based on the output signal.
[0006] The embodiment of the present disclosure also provides an LED driving method, which includes: converting a first voltage into a second voltage based on a control input, the second voltage having a voltage difference relative to the first voltage; generating an output signal based on the second voltage; and controlling the brightness of the LED based on the output signal. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Embodiments and various aspects of the present disclosure are presented in the following detailed description and accompanying drawings.The various features shown in the drawings are not drawn to scale.
[0008] Figure 1 A schematic diagram structure of an exemplary LED driving system according to some embodiments of the present disclosure is shown.
[0009] Figure 2 An exemplary relationship between the second voltage and the output signal according to some embodiments of the present disclosure is shown.
[0010] Figure 3 An exemplary relationship between an input PWM signal and an output signal according to some embodiments of the present disclosure is shown.
[0011] Figure 4 Another exemplary relationship between the second voltage and the output signal according to some embodiments of the present disclosure is shown.
[0012] Figure 5 Another block diagram of an exemplary LED driving system according to some embodiments of the present disclosure is shown.
[0013] Figure 6 A flow chart of an exemplary LED driving method according to some embodiments of the present disclosure is shown. DETAILED DESCRIPTION
[0014] Reference will now be made in detail to exemplary embodiments, examples of which are shown in the accompanying drawings. The following description refers to the accompanying drawings, in which the same numbers in different drawings represent the same or similar elements, unless otherwise indicated. The implementations set forth in the following description of the exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of devices and methods consistent with the aspects listed in the appended claims and related to the present invention. Specific aspects of the present disclosure are described in more detail below. If there is a conflict with terms and / or definitions incorporated by reference, the terms and definitions provided herein shall prevail.
[0015] Figure 1 FIG. 1 shows a block diagram of an exemplary LED driving system 100 according to some embodiments of the present disclosure. Figure 1 , the LED driving system 100 includes a conversion circuit 110, a driving circuit 120, a control circuit 130, and an LED 140. An input of the driving circuit 120 is coupled to an output of the conversion circuit 110. A first input of the control circuit 130 is coupled to the output of the driving circuit 120, and an output of the control circuit 130 is coupled to the LED 140 to control the brightness (e.g., grayscale) of the LED 140. In some embodiments, both the conversion circuit 110 and the control circuit 130 are coupled to an operating voltage Vdd. In some embodiments, the conversion circuit 110 may include one or more control input pins VSET for receiving a plurality of bits representing a control input as input. The conversion circuit 110 may be implemented by a chip.
[0016] The conversion circuit 110 is configured to convert a first voltage, i.e., an operating voltage Vdd, into a second voltage Vdv based on a control input received on one or more pins VSET. The second voltage Vdv has a voltage difference Vgs with the first voltage Vdd. The first voltage Vdd, i.e., the operating voltage, may be, for example, +5V. The second voltage Vdv is lower than the first voltage Vdd, for example, in the range of +2V to +3V. When determining the range of the second voltage Vdv, the range of the voltage difference Vgs is determined, Vgs=Vdd-Vdv. In this example, the range of the voltage difference Vgs is within the range of 1V, i.e., 3V-2V=1V. The range of the voltage difference Vgs can be quantified and adjusted in response to the control input. Therefore, by adjusting the control input at different levels, different values of the second voltage Vdv can be generated. In some embodiments, the control input is set by multiple bits, for example, the control input is configured by the one or more pins VSET of the chip. The VSET pin can be configured to receive 8 bits, 10 bits, or 12 bits, etc. representing the control input. VSET is a multi-bit input, and the control input can be received as a binary combination. For example, for an 8-bit input, the range of VSET<7:0> can be (00000000) to (11111111). In this example, if the 1V variation range of the voltage difference Vgs is quantized into 8 bits (for example, the one or more pins configured for receiving VSET are pins with 8 bits), the voltage difference range (for example, 1V) is divided into 256 levels, and the voltage variation of each level is 1 / 256V. Accordingly, the conversion circuit 110 can convert and output 256 voltage values of the second voltage Vdv. For example, when VSET<7:0>=(00000000), the voltage difference Vgs has a minimum value, for example, 2V. When VSET<7:0>=(1111111111), the voltage difference Vgs has a maximum value, for example, 3V. In some embodiments, if the 1V range of the voltage difference Vgs is quantized to 10 bits, the voltage difference range is divided into 1024 levels, and the voltage variation of each level is 1 / 1024 V. Accordingly, the conversion circuit 110 can convert and output 1024 voltage values of the second voltage Vdv. In some embodiments, if the 1V range of the voltage difference Vgs is quantized to 12 bits, the voltage difference range is divided into 4096 levels, and the voltage variation of each level is 1 / 4096V. Accordingly, the conversion circuit 110 can convert and output 4096 voltage values of the second voltage Vdv. Therefore, the conversion circuit 110 can convert and output the second voltage Vdv to different sizes based on the control input.
[0017] The driving circuit 120 is coupled to the conversion circuit 110 and is configured to generate an output signal based on the second voltage Vdv. For example, the output signal of the driving circuit 120 changes with the change of the second voltage Vdv. For example, Figure 2 FIG. 2 shows an exemplary relationship between the second voltage Vdv and the output signal of the driving circuit 120 according to some embodiments of the present disclosure. Figure 2 As shown, the voltage of the output signal of the driving circuit 120 follows the second voltage Vdv. When the second voltage Vdv increases, the output signal increases; and when the second voltage Vdv decreases, the output signal decreases. In some embodiments, the output signal of the driving circuit 120 can be a digital signal, such as a pulse width modulation (PWM) signal. Again referring to Figure 1 , the drive circuit 120 is coupled to receive the input PWM signal PWM_IN. The drive circuit 120 is configured to determine the output signal PWM_OUT based on the input signal PWM_IN and the second voltage Vdv. The duty cycle of the output signal PWM_OUT is determined based on the input signal PWM_IN. The high level of the output signal PWM_OUT may be the same as the voltage of the input signal PWM_IN. In this example, the voltage of PWM_IN is the same as the operating voltage Vdd. In some embodiments, the voltage of PWM_IN may be different from the operating voltage Vdd. The low level of the output signal PWM_OUT is determined based on the operating voltage Vdd and the second voltage Vdv. Figure 3 FIG. 2 shows an exemplary relationship between an input PWM signal and an output signal PWM_OUT according to some embodiments of the present disclosure. Figure 3 As shown, the duty cycle and frequency of the output signal PWM_OUT are the same as the duty cycle and frequency of the input signal PWM_IN. The high level of the output signal PWM_OUT is equal to the working voltage Vdd, and the low level of the output signal PWM_OUT is equal to the second voltage Vdv. Figure 4 2 shows another exemplary relationship between the second voltage Vdv and the output signal PWM_OUT according to some embodiments of the present disclosure. More specifically, Figure 4 The input signal PWM_IN, the second voltage Vdv and the output signal PWM_OUT are shown. Figure 4 As shown, the low level of the output signal PWM_OUT varies with the second voltage Vdv. As described above, since the second voltage Vdv can be adjusted to different magnitudes, the output signal PWM_OUT can be changed to different magnitudes.
[0018] In some embodiments, the duty cycle of the output signal PWM_OUT can be adjusted within a pulse cycle, that is, the ratio of the output high level Vdd to the output low level Vdv within a pulse cycle can be adjusted. For example, the duty cycle of the output signal PWM_OUT can be adjusted by adjusting the duty cycle of the input signal PWM_IN. Therefore, the brightness of the LED can also be controlled by the adjustment.
[0019] Return to reference Figure 1 The control circuit 130 is coupled to the driving circuit 120 and is configured to control the brightness of the LED 140 (eg, the grayscale of the display) based on the output signal PWM_OUT. The control circuit 130 generates an output current I based on the output signal out . Output current I out The brightness of LED 140 can be controlled. out When the output current I out When is high, the brightness of LED 140 is high. The control circuit 130 can generate an output current I out The more levels there are, the finer the grayscale that can be achieved. Since the output signal PWM_OUT can be changed to different sizes, for example, in 256 levels, 1024 levels, or 4096 levels, the output current I generated based on the output signal PWM_OUT is out It can also be adjusted to different sizes (e.g., levels). out The brightness of LED 140 can be controlled in multiple levels, which significantly improves the fineness of the display.
[0020] In some embodiments, the control circuit 130 can be further connected to a working voltage Vdd. out Determined by comparing the output signal with the operating voltage Vdd. In this example, since the variation range of the voltage difference Vgs between the operating voltage Vdd and the second voltage Vdv is quantified into multiple levels, and the low level of the output signal PWM_OUT is equal to Vdv, the output current I directly determined by the voltage difference Vgs can be quantified more accurately. out , thereby improving the display fineness.
[0021] In some embodiments, LED 140 can be an LED having any color, for example, LED 140 is one of a white LED, a red LED, a blue LED, or a yellow LED.
[0022] Figure 5 Another block diagram of an exemplary LED driving system 500 according to some embodiments of the present disclosure is shown. Figure 5 The LED driving system 500 includes: Figure 1The aforementioned conversion circuit 110 and the driving circuit 120 of the configuration shown. The system 500 further includes a control circuit 130 provided as a MOS (metal oxide semiconductor) transistor 131. The source of the MOS transistor 131 is coupled to the first voltage Vdd, the gate of the MOS transistor 131 is coupled to the output of the driving circuit 120, and the drain of the MOS transistor 131 is coupled to the LED 140. In the system 500, the LED 140 includes a diode 141. The drain of the MOS transistor 131 is coupled to the anode of the diode 141. The cathode of the diode 141 is connected to the ground V SS When the output signal PWM_OUT of the driving circuit 120 is at a low level, Vgs=Vdd-Vdv, and the MOS transistor 131 is turned on. By adjusting the configuration of VSET (e.g., a digital value), the variation range of Vgs can be quantified into many levels, such as 256, 1024, 4096, etc. In the system 500, the voltage difference Vgs between the source and the gate of the MOS transistor 131 is proportional to the output current I flowing through the LED 140. out By adjusting the voltage difference Vgs, different I out value, and when different I out When passing through the LED 140, different brightness can be generated. The conversion circuit 110 is configured to adjust the low level Vdv of the output signal PWM_OUT, which can be quantized to 8 bits, 10 bits and 12 bits. Therefore, a very large number of low level Vdv values can be obtained. Therefore, brightness adjustment (for example, the grayscale of image display) becomes more accurate. The drive circuit 120 is configured to adjust the duty cycle of the output signal PWM_OUT within a pulse period by adjusting the duty cycle of the input signal PWM_IN. By adjusting the duty cycle of the output signal PWM_OUT, the output current I out , thereby adjusting the brightness of LED 140.
[0023] Figure 6 1 shows a flow chart of an exemplary LED driving method 600 according to some embodiments of the present disclosure. The method 600 may be performed by the LED driving system 100. Figure 6 As shown, method 600 includes steps 602 to 608 .
[0024] In step 602, the first voltage Vdd is converted to a second voltage Vdv having a voltage difference based on the control input. The second voltage Vdv has a voltage difference Vgs with the first voltage Vdd. The first voltage Vdd may be an operating voltage, such as +5V. The second voltage Vdv is lower than the first voltage Vdd, for example, in the range of +2V to +3V. When determining the range of the second voltage Vdv, the range of the voltage difference Vgs is determined. In this example, the range of the voltage difference Vgs is within the range of 1V, i.e., 3V-2V=1V.
[0025] In step 604, the variation range of the voltage difference is quantified based on the digital value of the control input. The variation range of the voltage difference Vgs can be quantified and adjusted by the control input. Therefore, different values of the second voltage Vdv can be generated by adjusting the control input. In some embodiments, the control input is set by multiple bits, for example, the control input is set by one (or more) pins VSET of the chip. VSET can be one or more pins with 8 bits, 10 bits, or 12 bits, etc., which can be determined by the selected chip. VSET is a multi-bit input, and the control input can be received as a binary combination. For example, for an 8-bit input, the range of VSET<7:0> can be (00000000) to (11111111). In this example, if the variation range of 1V of the voltage difference Vgs is quantized into 8 bits (for example, one (or more) pins VSET receives 8 bits), the voltage difference range (for example, 1V) is divided into 256 levels, and the voltage variation of each level is 1 / 256V. Accordingly, the conversion circuit 110 can convert and output 256 voltage values of the second voltage Vdv. If the 1V variation range of the voltage difference Vgs is quantized to 10 bits, the voltage difference range is divided into 1024 levels, and the voltage variation of each level is 1 / 1024V. Accordingly, the conversion circuit 110 can convert and output 1024 voltage values of the second voltage Vdv. If the 1V variation range of the voltage difference Vgs is quantized to 12 bits, the voltage difference range is divided into 4096 levels, and the voltage variation of each level is 1 / 4096V. Accordingly, the conversion circuit 110 can convert and output 4096 voltage values of the second voltage Vdv. Therefore, the conversion circuit 110 can convert and output the second voltage Vdv with different sizes based on the control input.
[0026] In step 606, an output signal is generated based on the second voltage Vdv. For example, the output signal PWM_OUT is changed based on the second voltage Vdv. For example, the voltage of the output signal follows the second voltage Vdv, such as Figure 2As shown. When the second voltage Vdv increases, the output signal increases; and when the second voltage Vdv decreases, the output signal decreases. In some embodiments, the output signal may be a digital signal, such as a PWM signal. The input PWM signal PWM_IN may be another input to the drive circuit 120. The output signal PWM_OUT is determined based on the input signal PWM_IN and the second voltage Vdv. The duty cycle of the output signal PWM_OUT is determined based on the input signal PWM_IN. The high level of the output signal PWM_OUT may be the same as the voltage of the input signal PWM_IN. In this example, the voltage of PWM_IN is the same as the operating voltage Vdd. In some embodiments, the voltage of PWM_IN may be different from the operating voltage Vdd. The low level of the output signal PWM_OUT is determined based on the operating voltage Vdd and the second voltage Vdv. For example, the duty cycle and frequency of the output signal PWM_OUT may be the same as the duty cycle and frequency of the input signal PWM_IN. As Figure 3 As shown, the high level of the output signal PWM_OUT is equal to the working voltage Vdd, and the low level of the output signal PWM_OUT is equal to the second voltage Vdv. In some embodiments, the low level of the output signal PWM_OUT changes with the second voltage Vdv, such as Figure 4 As described above, since the second voltage Vdv can be adjusted to different magnitudes, the output signal can be changed to different magnitudes.
[0027] In some embodiments, the duty cycle of the output signal PWM_OUT can be adjusted within a pulse cycle, that is, the ratio of the output high level Vdd to the output low level Vdv within a pulse cycle can be adjusted. For example, the duty cycle of the output signal PWM_OUT can be adjusted by adjusting the duty cycle of the input signal PWM_IN. Therefore, the brightness of the LED can also be controlled by the adjustment.
[0028] At step 608, the brightness of the LED is controlled based on the output signal. The current I for LED 140 LED Based on the output signal, it can control the brightness of LED 140. LED When the current I LED When the current I is high, the brightness of LED 140 is high. LED The more levels there are, the finer the grayscale can be. LED Since the output signal can be changed to different levels, such as 256 levels, 1024 levels, or 4096 levels, the current I generated based on the output signal LED It can also be adjusted to different sizes (e.g. levels). LEDThe brightness of LED 140 can be controlled in multiple levels, which significantly improves the fineness of the display.
[0029] In some embodiments, the current I is determined by comparing the output signal with the operating voltage Vdd. LED In this example, since the variation range of the voltage difference Vgs between the operating voltage Vdd and the second voltage Vdv is quantified into multiple levels and the low level of the output signal is equal to Vdv, the current I directly determined by the voltage difference Vgs can be quantified more accurately. LED , thus showing more refined.
[0030] It should be noted that relational terms, such as "first" and "second", herein are used only to distinguish an entity or operation from another entity or operation, without requiring or implying any actual relationship or order between these entities or operations. In addition, the words "comprising", "having", "containing", and "including" and other similar forms are intended to be equivalent in meaning and are open-ended, and one or more items following any of these words are not meant to be an exhaustive list of such one or more items, or to be limited to the listed one or more items.
[0031] As used herein, unless expressly stated otherwise, the term "or" encompasses all possible combinations unless not feasible. For example, if it is stated that a database may include A or B, then unless expressly stated otherwise or not feasible, the database may include A, or B, or A and B. As a second example, if it is stated that a database may include A, B, or C, then unless expressly stated otherwise or not feasible, the database may include A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C.
[0032] In the foregoing description, embodiments have been described with reference to many specific details, which may vary depending on the implementation. Certain changes and modifications may be made to the described embodiments. Other embodiments will be apparent to those skilled in the art in view of the description and practice of the invention disclosed herein. The description and examples are intended to be considered as merely exemplary, and the true scope and spirit of the invention are indicated by the following claims. The order of steps shown in the accompanying drawings is also intended to be for illustrative purposes only and is not intended to be limited to any particular order of steps. Therefore, it will be appreciated by those skilled in the art that these steps may be performed in different orders while implementing the same method.
[0033] In the drawings and the specification, exemplary embodiments have been disclosed. However, many variations and modifications may be made to these embodiments. Therefore, although specific terms are employed, they are used only in a general and descriptive sense and not for the purpose of limitation.
Claims
1. An LED driving system, comprising: a conversion circuit configured to convert a first voltage into a second voltage having a voltage difference relative to the first voltage based on a control input; a driving circuit coupled to the conversion circuit to receive the second voltage and configured to generate an output signal based on the second voltage; as well as A control circuit is coupled to the drive circuit and is configured to control the brightness of the LED based on the output signal.
2. The LED driving system according to claim 1, wherein: The variation range of the voltage difference is quantified by the digital value of the control input.
3. The LED driving system according to claim 2, wherein: When the variation range is quantized to 8 bits, the variation range is divided into 256 levels; when the variation range is quantized to 10 bits, the variation range is divided into 1024 levels; and when the variation range is quantized to 12 bits, the variation range is divided into 4096 levels.
4. The LED driving system according to any one of claims 1 to 3, wherein: The drive circuit is coupled to receive an input signal, and the output signal is generated based on the input signal and the second voltage.
5. The LED driving system according to claim 4, wherein: The input signal is an input pulse width modulation (PWM) signal, and the output signal is an output PWM signal.
6. The LED driving system according to claim 5, wherein: The output PWM signal includes a high level at a first voltage and a low level at a second voltage in a pulse period.
7. The LED driving system according to claim 5 or 6, wherein: The duty cycle of the output PWM signal is adjustable within the pulse period.
8. The LED driving system according to any one of claims 1 to 7, wherein: The control circuit includes a metal oxide semiconductor (MOS) transistor, a source of the MOS transistor is coupled to receive the first voltage, a gate of the MOS transistor is coupled to the output of the drive circuit, and a drain of the MOS transistor is coupled to the LED.
9. The LED driving system according to claim 8, wherein: The voltage difference between the first voltage and the second voltage is equal to a voltage difference between a source and a gate of the MOS transistor.
10. The LED driving system according to claim 8 or 9, wherein: The brightness of the LED is controlled based on the current output of the drain.
11. The LED driving system according to any one of claims 1 to 10, wherein: The LED is one of a white LED, a red LED or a blue LED.
12. A LED driving method, comprising: converting a first voltage into a second voltage having a voltage difference relative to the first voltage based on a control input; generating an output signal based on the second voltage; as well as The brightness of the LED is controlled based on the output signal.
13. The method according to claim 12, wherein: After converting the first voltage to a second voltage based on a control input, the method further comprises: The variation range of the voltage difference is quantified based on the digital value of the control input.
14. The method according to claim 13, wherein: When the variation range of the voltage difference is quantized to 8 bits, the variation range is divided into 256 levels; when the variation range is quantized to 10 bits, the variation range is divided into 1024 levels; and when the variation range is quantized to 12 bits, the variation range is divided into 4096 levels.
15. The method according to any one of claims 12 to 14, wherein: Generating the output signal based on the second voltage further comprises: The output signal is generated based on the second voltage and an input signal.
16. The method according to claim 15, wherein: The input signal is an input pulse width modulation (PWM) signal, and the output signal is an output PWM signal.
17. The method according to claim 16, wherein: The output PWM signal includes a high level at a first voltage and a low level at a second voltage in a pulse period.
18. The method according to claim 16 or 17, wherein: The duty cycle of the output PWM signal is adjustable within the pulse period.
19. The method according to any one of claims 12 to 18, wherein: After generating the output signal based on the second voltage, the method further comprises: controlling a current of the LED based on the output signal; and Controlling the brightness of the LED based on the output signal further comprises: The brightness of the LED is controlled based on the current.
20. The method according to claim 19, wherein: The brightness of the LED is positively correlated with the current.