CN102215616A - PWM (pulse width modulation)-based LED (light emitting diode) linear dimming circuit - Google Patents
PWM (pulse width modulation)-based LED (light emitting diode) linear dimming circuit Download PDFInfo
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- CN102215616A CN102215616A CN2010101416567A CN201010141656A CN102215616A CN 102215616 A CN102215616 A CN 102215616A CN 2010101416567 A CN2010101416567 A CN 2010101416567A CN 201010141656 A CN201010141656 A CN 201010141656A CN 102215616 A CN102215616 A CN 102215616A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
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Abstract
The invention provides a PWM (pulse width modulation)-based LED (light emitting diode) linear dimming circuit and relates to an LED linear dimming system. The circuit provided by the invention comprises a fixed-frequency high-frequency pulse signal source and a duty cycle calculation device, wherein a PWM pulse dimming signal and the high-frequency pulse signal are compared so as to obtain the duty cycle of the dimming signal; a pulse duty cycle and analog voltage converter can be used for regulating the size of an output analog voltage signal according to the duty cycle obtained by the duty cycle calculation device. The output voltage can not be influenced by the input frequency; and large-sized filter capacitors and large-sized resistors are not required; and meanwhile, the response speed is fast, the anti-jamming capacity is strong and the noises probably caused by a PWM signal can be completely removed.
Description
Technical field
The present invention relates to a kind of light-emitting diode linearity light adjusting system system, particularly a kind of PWM-type light-emitting diode linearity light adjusting circuit that need not filter element.
Background technology
Present led lighting or dimming mode backlight mainly contain two kinds: pulse-width modulation (PWM) or numeric string connecting port control mode, being reacted to led current then has continuous linear light modulation and switch intermittent type light-modulating mode.In a lot of applications, the mode of the continuous linear light modulation of light-emitting diode (LED) electric current is favored especially, because it does not have or return to reduce unnecessary audio-frequency noise and to the dynamic impulsion of power supply.Mobile phone is exactly one of them topmost application product.
But up to the present, by pulse-width modulation (PWM) input LED being carried out linear light modulation all is to pass through the linear dimmer voltage that capacitance-resistance (R-C) is carried out filtering to pwm signal and produced control LED electric current through amplifier in chip for driving or outside the chip.As shown in Figure 1.The subject matter of this control mode is that its output voltage can have bigger ripple when frequency input signal is relatively lower, because the existence of Resistor-Capacitor Unit, be not can produce audio-frequency noise when frequency during in audiorange, this is a very big problem in the application of mobile phone.In order to address this problem, filtering capacitance-resistance value just must be enough greatly, but so the cost of system, volume and response time all can increase, the output voltage precision also can change with frequency input signal, practical application is severely limited.
Therefore, how to provide the drive circuit that a kind of cost is low, volume is little, noise is little and response speed is fast, become the problem that those skilled in the art need solve.
Summary of the invention
In order to solve problems of the prior art, the invention provides a kind of PWM-type light-emitting diode linearity light adjusting circuit, remove filter element by changing the light modulation principle, remove the light modulation noise, and reach the purpose that reduces cost, reduces volume.
For this reason, the present invention is by the following technical solutions:
PWM-type light-emitting diode linearity light adjusting circuit comprises pwm pulse dim signal input and analog voltage signal output, it is characterized in that also comprising:
The high-frequency pulse signal source of fixed frequency, its frequency is greater than pwm pulse dim signal frequency;
The duty ratio calculation element compares the signal in pwm pulse dim signal and high-frequency pulse signal source, obtains the duty ratio of dim signal;
Pulse duty cycle-aanalogvoltage transducer has reference voltage input terminal, the size of the duty cycle adjustment output analog voltage signal that obtains according to the duty ratio calculation element.
The present invention presets the duty ratio that fixing high-frequency pulse signal obtains the pwm pulse dim signal by the mode basis with two kinds of signal comparisons, again according to the size of duty cycle adjustment output voltage signal, reach the light modulation purpose, do not have filter element in the circuit, noise and the ripple of having avoided capacitance-resistance to bring.
As to the improving and replenishing of technique scheme, the present invention further takes the following technical measures or the combination in any of these measures:
Described high-frequency pulse signal source is a radio-frequency generator, the signal frequency of its output is greater than 10 times of the highest frequencies of pwm pulse dim signal, under high a lot of situation, be convenient to prepare to calculate the dim signal duty ratio than pwm pulse dim signal frequency at high-frequency pulse signal.
Described duty ratio calculation element is a counter, by the high-frequency pulse signal pulse number during calculating pwm pulse dim signal high potential and the electronegative potential, obtains the duty ratio of pwm pulse dim signal.
Described duty ratio calculation element is a timer, calculates pwm pulse dim signal high potential and electronegative potential phase institute's elapsed time by high-frequency pulse signal, obtains the duty ratio of pwm pulse dim signal.
Described pulse duty cycle-aanalogvoltage transducer is according to the duty cycle adjustment output voltage of dim signal and the ratio of reference voltage, i.e. output voltage=reference voltage * duty ratio.
Beneficial effect: output voltage of the present invention is not subjected to the influence of incoming frequency, the output voltage precision low pwm signal input duty cycle also can guarantee+/-1%VREF in, need not bulky filter capacitor and resistance, response speed is fast, antijamming capability is strong, removes the noise that pwm signal may cause fully.
Description of drawings
Fig. 1 is existing light adjusting circuit schematic diagram;
Fig. 2 is a circuit theory schematic diagram of the present invention.
Embodiment
PWM-type light-emitting diode linearity light adjusting circuit as shown in Figure 2, the PWM linearity light adjusting circuit structure of filtering free circuit comprise light modulation core function unit (shown in the frame of broken lines) and outer member.0%～100%)-aanalogvoltage transducer (voltage output range: 0V～VREF) the light modulation core function unit comprises high frequency pulse generator, pulsewidth counter (or timer), reference voltage source (VREF) and pulse duty cycle (input range:.
The frequency of high frequency pulse generator need be higher more than 10 to 20 times than the highest PWM frequency input signal that may run in using.Following table is possible system's input and output contrast table.
| The PWM input duty cycle | The output of pulsewidth counter | The LED dimmer voltage |
| 0％ | 0 | 0 |
| 1％ | 1 | 1％VREF |
| 5％ | 5 | 5％VREF |
| 50％ | 50 | 50％VREF |
| 100％ | 100 | VREF |
Be different from prior art, the present invention need not filter element, adopt digital operation, thereby duty cycle conversion voltage accuracy height, strong interference immunity and be not subjected to the input pulse frequency, thereby make system not need any other outer member also can use in wider pulse frequency scope, antijamming capability is strong, dimming light-emitting diode precision height (error is less than 3% rated current), and can get rid of the audio frequency noise that may run into when light-emitting diode uses conventional P WM light-dimming method fully.
Should be pointed out that present embodiment just lists expressivity principle of the present invention and effect are described, but not be used to limit the present invention.Any personnel that are familiar with this technology all can make amendment to the foregoing description under spirit of the present invention and scope.Therefore, the scope of the present invention should be listed as claims.
Claims (5)
1. PWM-type light-emitting diode linearity light adjusting circuit comprises pwm pulse dim signal input and analog voltage signal output, it is characterized in that also comprising:
The high-frequency pulse signal source of fixed frequency, its frequency is greater than pwm pulse dim signal frequency;
The duty ratio calculation element compares the signal in pwm pulse dim signal and high-frequency pulse signal source, obtains the duty ratio of dim signal;
Pulse duty cycle-aanalogvoltage transducer has reference voltage input terminal, the size of the duty cycle adjustment output analog voltage signal that obtains according to the duty ratio calculation element.
2. PWM-type light-emitting diode linearity light adjusting circuit according to claim 1, it is characterized in that: described high-frequency pulse signal source is a radio-frequency generator, the signal frequency of its output is greater than 10 times of the highest frequencies of pwm pulse dim signal.
3. according to the PWM-type light-emitting diode linearity light adjusting circuit of claim 2, it is characterized in that: described duty ratio calculation element is a counter, by the high-frequency pulse signal pulse number during calculating pwm pulse dim signal high potential and the electronegative potential, obtain the duty ratio of pwm pulse dim signal.
4. according to the PWM-type light-emitting diode linearity light adjusting circuit of claim 2, it is characterized in that: described duty ratio calculation element is a timer, calculate pwm pulse dim signal high potential and electronegative potential phase institute's elapsed time by high-frequency pulse signal, obtain the duty ratio of pwm pulse dim signal.
5. according to the described PWM-type light-emitting diode of claim 1 to 4 linearity light adjusting circuit, it is characterized in that: described pulse duty cycle-aanalogvoltage transducer is according to the duty cycle adjustment output voltage of dim signal and the ratio of reference voltage, i.e. output voltage=reference voltage * duty ratio.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101416567A CN102215616A (en) | 2010-04-08 | 2010-04-08 | PWM (pulse width modulation)-based LED (light emitting diode) linear dimming circuit |
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| CN2010101416567A CN102215616A (en) | 2010-04-08 | 2010-04-08 | PWM (pulse width modulation)-based LED (light emitting diode) linear dimming circuit |
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| CN102215616A true CN102215616A (en) | 2011-10-12 |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102402953A (en) * | 2011-12-08 | 2012-04-04 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and display device applying same |
| CN102542981A (en) * | 2011-12-14 | 2012-07-04 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and displaying device applied by same |
| CN102655706A (en) * | 2012-05-04 | 2012-09-05 | 成都芯源***有限公司 | Light emitting element driver, control circuit and control method thereof |
| CN102740564A (en) * | 2012-06-28 | 2012-10-17 | 上海新进半导体制造有限公司 | Light emitting diode (LED) driving circuit and control method of LED |
| CN103037573A (en) * | 2012-11-20 | 2013-04-10 | 无锡中星微电子有限公司 | Dimming circuit |
| CN103150999A (en) * | 2013-03-29 | 2013-06-12 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit and liquid crystal display device |
| CN104299603A (en) * | 2014-10-24 | 2015-01-21 | 京东方科技集团股份有限公司 | Brightness adjustment device and method, LED backlight device and liquid crystal display device |
| US9018859B2 (en) | 2013-03-29 | 2015-04-28 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | LED backlight driving circuit and LCD device |
| CN104822197A (en) * | 2015-04-20 | 2015-08-05 | 南京矽力杰半导体技术有限公司 | Analog dimming control method, control circuit and LED drive circuit using the analog dimming control method and control circuit |
| CN106444459A (en) * | 2016-11-15 | 2017-02-22 | 贵州大学 | Control apparatus for detecting duty ratio of rectangular wave signal in real time and realization method thereof |
| CN109548252A (en) * | 2018-11-19 | 2019-03-29 | 广州腾龙电子塑胶科技有限公司 | Pwm signal conversion method, device, computer equipment and converter pwm signal |
| CN112074046A (en) * | 2020-08-27 | 2020-12-11 | 深圳市晟碟半导体有限公司 | Counting filter circuit, device and counting method thereof |
| CN112489587A (en) * | 2019-08-24 | 2021-03-12 | 华源智信半导体(深圳)有限公司 | Power line communication in a display device with distributed driver circuits |
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| CN101657050A (en) * | 2008-08-22 | 2010-02-24 | 晶宏半导体股份有限公司 | Light-emitting diode brightening drive device |
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Cited By (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102402953A (en) * | 2011-12-08 | 2012-04-04 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and display device applying same |
| WO2013082825A1 (en) * | 2011-12-08 | 2013-06-13 | 深圳市华星光电技术有限公司 | Drive circuit and method of light-emitting diode, and display device using same |
| CN102402953B (en) * | 2011-12-08 | 2014-07-16 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and display device applying same |
| CN102542981A (en) * | 2011-12-14 | 2012-07-04 | 深圳市华星光电技术有限公司 | Driving circuit and method of light-emitting diode and displaying device applied by same |
| CN102655706A (en) * | 2012-05-04 | 2012-09-05 | 成都芯源***有限公司 | Light emitting element driver, control circuit and control method thereof |
| CN102740564B (en) * | 2012-06-28 | 2015-04-22 | 上海新进半导体制造有限公司 | Light emitting diode (LED) driving circuit and control method of LED |
| CN102740564A (en) * | 2012-06-28 | 2012-10-17 | 上海新进半导体制造有限公司 | Light emitting diode (LED) driving circuit and control method of LED |
| CN103037573A (en) * | 2012-11-20 | 2013-04-10 | 无锡中星微电子有限公司 | Dimming circuit |
| US9018859B2 (en) | 2013-03-29 | 2015-04-28 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | LED backlight driving circuit and LCD device |
| CN103150999A (en) * | 2013-03-29 | 2013-06-12 | 深圳市华星光电技术有限公司 | Light-emitting diode (LED) backlight driving circuit and liquid crystal display device |
| CN104299603A (en) * | 2014-10-24 | 2015-01-21 | 京东方科技集团股份有限公司 | Brightness adjustment device and method, LED backlight device and liquid crystal display device |
| CN104822197A (en) * | 2015-04-20 | 2015-08-05 | 南京矽力杰半导体技术有限公司 | Analog dimming control method, control circuit and LED drive circuit using the analog dimming control method and control circuit |
| CN106444459A (en) * | 2016-11-15 | 2017-02-22 | 贵州大学 | Control apparatus for detecting duty ratio of rectangular wave signal in real time and realization method thereof |
| CN106444459B (en) * | 2016-11-15 | 2023-04-28 | 贵州大学 | Control device for detecting duty ratio of rectangular wave signal in real time and implementation method |
| CN109548252A (en) * | 2018-11-19 | 2019-03-29 | 广州腾龙电子塑胶科技有限公司 | Pwm signal conversion method, device, computer equipment and converter pwm signal |
| CN112489587A (en) * | 2019-08-24 | 2021-03-12 | 华源智信半导体(深圳)有限公司 | Power line communication in a display device with distributed driver circuits |
| US11257421B2 (en) | 2019-08-24 | 2022-02-22 | Huayuan Semiconductor (Shenzhen) Limited Company | Display device with single package light emitting diode and driver circuit |
| US11289011B2 (en) | 2019-08-24 | 2022-03-29 | Huayuan Semiconductor (Shenzhen) Limited Company | Power line communication in a display device with distributed driver circuits |
| CN112074046A (en) * | 2020-08-27 | 2020-12-11 | 深圳市晟碟半导体有限公司 | Counting filter circuit, device and counting method thereof |
| CN112074046B (en) * | 2020-08-27 | 2022-10-14 | 深圳市晟碟半导体有限公司 | Counting filter circuit, device and counting method thereof |
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Application publication date: 20111012 |