A deep dimming device and method for LED lamps

Abstract

The application relates to a deep dimming device and method for an LED lamp, which comprises a dimming control circuit, a power control circuit, a feedback circuit, an input-output signal channel and a power output loop; the current setting output end of the dimming control circuit is connected with the reference end of the feedback circuit, the current collection end of the feedback circuit is connected with the LED lamp through the input-output signal channel, the error signal output end of the feedback circuit is connected with the power control circuit, the power control circuit is connected with the power output loop through the input-output signal channel, and the power output loop is connected with the LED lamp. Compared with the prior art, the application has the advantages of realizing high-precision deep dimming and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the dimming technology of LED lamp, and particularly to a deep dimming device and method for LED lamp. BACKGROUND

[0002] At present, it is an inevitable trend that LED lighting replaces fluorescent daylight lamp and fluorescent energy-saving lamp. Since LED element adapts to rapid change of current when working, it is very convenient to design dimming function for LED driving power supply. The use of LED dimming lamp brings convenience to energy-saving and low-carbon work and life.

[0003] Generally, the dimming power supply is nominally one thousandth of the dimming depth, but the error of output current of these dimming power supplies is large and the precision is low when deep dimming. For example, under the condition of setting the same brightness level, the output current of LED load voltage is small and the brightness is low; the output current of LED load voltage is large and the brightness is high, which does not meet the requirements of dimming brightness curve and color mixing effect. SUMMARY

[0004] The present application is to overcome the defects of the prior art and provide a deep dimming device and method for LED lamp.

[0005] The object of the present application can be achieved by the following technical solutions.

[0006] According to one aspect of the present application, a deep dimming device for LED lamp is provided, comprising a dimming control circuit, a power supply control circuit, a feedback circuit, an input-output signal path and a power output loop.

[0007] The current setting output end of the dimming control circuit is connected with the reference end of the feedback circuit, the current collection end of the feedback circuit is connected with the LED lamp through the input-output signal path, the error signal output end of the feedback circuit is connected with the power supply control circuit, the power supply control circuit is connected with the power output loop through the input-output signal path, and the power output loop is connected with the LED lamp.

[0008] As a preferred technical solution, the current setting output end of the dimming control circuit adds the current setting value to the reference end of the feedback circuit, so as to accurately control the output current value.

[0009] As a preferred technical solution, the synchronous pulse output end of the dimming control circuit is connected with the step pulse input end of the power supply control circuit.

[0010] As a preferred technical solution, the driving output end of the power supply control circuit is connected with the working frequency input end of the dimming control circuit.

[0011] As a preferred technical scheme, the sleep control input end of the dimming control circuit is connected with the enable end of the input and output signal path, for inserting a controllable length of idle period between each working period.

[0012] According to another aspect of the present application, a dimming method using the deep dimming device for LED lamp is provided, which comprises a current setting value dimming sub-method and an idle period dimming sub-method.

[0013] As a preferred technical scheme, the current setting value dimming sub-method is specifically as follows:

[0014] The current setting value and the output current have a linear relationship, and when the current setting value reaches the lower limit, the working period and the output current of the LED load with different voltages are the same.

[0015] As a preferred technical scheme, the power control circuit comprises two modes of fixed frequency and variable frequency, and is specifically as follows:

[0016] a) for the fixed frequency mode power, the synchronization pulse is given to the power control circuit, so that the frequency of the power control circuit is synchronized with the trigger signal, and the working frequency is always the same as the trigger frequency;

[0017] b) for the variable frequency mode power, if the output current is greater than the working frequency and is lower than the limit frequency, the trigger pulse is output according to the working frequency of the power control circuit; when the output current decreases, the working frequency increases, and when the working frequency of the power control circuit is higher than the limit frequency, the synchronization pulse is output according to the limit frequency.

[0018] As a preferred technical scheme, the idle period dimming sub-method is specifically as follows: since the current contribution value of a single working period under the LED load with different voltages is a constant value, the output current value and the pulse output period have an inverse relationship, the output current value after inserting the idle period can be calculated, and the specific calculation is as follows:

[0019] Output current value = current contribution value of a single working period ÷ pulse output period;

[0020] Current contribution value of a single working period = lower limit value of current setting value * working period.

[0021] As a preferred technical scheme, when the current setting value reaches the lower limit and the inserted idle period is zero, it is the intersection point of the current setting value dimming sub-method and the idle period dimming sub-method.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] The present application does not need to consider different voltage LED load conditions when dimming, avoids complex operations such as curve fitting, table building and table searching, and also does not need to be corrected during product production, and only simple linear calculation can obtain precise small current output with feedback control, and high-precision deep dimming is realized. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a specific implementation block diagram of the present application.

[0025] Figure 2 is the current waveform and working frequency change condition of the present application when different current set values are adopted under the control mode of fixed frequency and variable frequency.

[0026] Figure 3 is the current waveform and working frequency change condition when the idle period dimming mode is adopted by the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0028] As shown in Figure 1 , the deep dimming device for LED lamp includes a dimming control circuit, a power control circuit, a feedback circuit, an input-output signal path and a power output loop.

[0029] The current set output end of the dimming control circuit is connected with the reference end of the feedback circuit, the current collection end of the feedback circuit is connected with the LED lamp through the input-output signal path, the error signal output end of the feedback circuit is connected with the power control circuit, the power control circuit is connected with the power output loop through the input-output signal path, and the power output loop is connected with the LED lamp.

[0030] The present application adds the current set value to the reference end of the feedback circuit to accurately control the output current value. When the current set value reaches the lower limit, the power switch frequency is synchronized with the external trigger signal, so that the power working period and the output current of the LED load of different voltages are the same, that is, the current contribution value of each working period is a constant value. At this time, the idle period with controllable length is inserted between each working period of it to realize the precise output of small current during deep dimming.

[0031] The present application adopts two ways to dim, that is, the current set value dimming mode and the idle period dimming mode.

[0032] 1. In the current set value dimming mode

[0033] As Figure 2 shown, the sleep control output signal is "1", the input and output signal path is always open, the set value of the output current is added to the reference end of the power feedback circuit, the output current collection end and the reference end of the feedback circuit are compared, the feedback circuit amplifies the error signal and outputs it to the control circuit, and then drives the power loop output. Since the DC gain of the feedback circuit is high, when the offset voltage of the feedback circuit is small, the output current has high control accuracy.

[0034] The control circuit of the power supply has two modes: fixed frequency and variable frequency.

[0035] a. For fixed frequency mode power supply, the synchronization pulse is given to the power supply control circuit, so that the frequency of the power supply control circuit is synchronized with the trigger signal, and the working frequency is always the same as the trigger frequency;

[0036] b. For variable frequency mode power supply, such as fixed off mode and critical mode power supply, when the output current is greater than the limit frequency, the synchronization pulse is output according to the working frequency of the control circuit; when the output current decreases, the working frequency increases; when the working frequency of the control circuit is higher than the limit frequency, the synchronization pulse is output according to the limit frequency, and the frequency of the power supply control circuit cannot continue to rise due to the clamping of the synchronization pulse. The working frequency is the limit frequency.

[0037] When the current set value reaches the lower limit and the idle period inserted is zero, it is the intersection point of the current set value dimming mode and the idle period dimming mode.

[0038] Summary: When the current set value is dimmed, there is a linear relationship between the current set value and the output current; when the current set value reaches the lower limit, the working period of the LED load with different voltages and the output current are the same. The current contribution value of a single working period = the lower limit value of the current set value * the working period, which is a constant value.

[0039] 2. When the idle period dimming mode is used, as Figure 3 shown, a controllable length of idle period is inserted between each working period, and the sum of the working period and the controllable length of the idle period is called the pulse output period. The pulse output period is triggered by the synchronization pulse, and the period of the control synchronization pulse is equal to the length of the control idle period. The sleep output control signal is only "1" during the working period, which is used to open the feedback circuit and the power supply control circuit, and only the current in the working period is feedback and controlled. In the idle period, the sleep control signal is "0", the feedback circuit and the control circuit of the power supply are closed and enter the sleep mode, and the input and output are frozen and will not change.

[0040] Summary: In the dimming mode of idle period, the current contribution value of single working period under different voltage LED load is constant, the output current value and the pulse output period are inversely proportional, and the output current value after inserting the idle period can be calculated. Output current value = single working period current contribution value ÷ pulse output period.

[0041] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be encompassed within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A deep dimming device for an LED lamp, characterized in that, The light modulation control circuit, the power supply control circuit, the feedback circuit, the input-output signal path and the power output loop are included. The current setting output end of the light modulation control circuit is connected with the reference end of the feedback circuit, the current collection end of the feedback circuit is connected with the LED lamp through the input-output signal path, the error signal output end of the feedback circuit is connected with the power supply control circuit, the power supply control circuit is connected with the power output loop through the input-output signal path, and the power output loop is connected with the LED lamp. The depth light modulation device includes a current setting value light modulation mode and an idle period light modulation mode, and the current setting value light modulation mode and the idle period light modulation mode are the interaction point when the current setting value reaches the lower limit and the inserted idle period is zero.

2. A deep dimming device for an LED lamp according to claim 1, characterized in that, The current setting output end of the light modulation control circuit adds the current setting value to the reference end of the feedback circuit, so as to accurately control the output current value.

3. A deep dimming device for an LED lamp according to claim 1, wherein, The synchronous pulse output end of the light modulation control circuit is connected with the step pulse input end of the power supply control circuit.

4. A deep dimming device for an LED lamp according to claim 1, wherein, The driving output end of the power supply control circuit is connected with the working frequency input end of the light modulation control circuit.

5. A deep dimming device for an LED lamp according to claim 1, wherein, The sleep control input end of the light modulation control circuit is connected with the enable end of the input-output signal path, so as to insert the controllable length idle period between each working period.

6. A dimming method using the depth dimming device for an LED lamp according to claim 1, characterized in that, The light modulation method includes a current setting value light modulation sub-method and an idle period light modulation sub-method.

7. The dimming method according to claim 6, wherein The current setting value light modulation sub-method is specifically as follows: The current setting value and the output current are in linear relationship, and when the current setting value reaches the lower limit, the working period and the output current of the LED load with different voltages are the same.

8. The dimming method according to claim 7, wherein, The power supply control circuit includes two modes of fixed frequency and variable frequency, and is specifically as follows: a) for the fixed frequency mode power supply, the synchronous pulse is given to the power supply control circuit, so that the frequency of the power supply control circuit is synchronized with the trigger signal, and the working frequency is always the same as the trigger frequency; b) for the variable frequency mode power supply, when the output current increases, the working frequency is lower than the limit frequency, and the trigger pulse is output according to the working frequency of the power supply control circuit; when the output current decreases, the working frequency increases, and when the working frequency of the power supply control circuit is higher than the limit frequency, the synchronous pulse output is output according to the limit frequency.

9. The dimming method according to claim 6, wherein, The idle period light modulation sub-method is specifically as follows: since the current contribution value of a single working period under the LED load with different voltages is a constant value, the output current value and the pulse output period are inversely proportional, the output current value after inserting the idle period is calculated, and the specific calculation is as follows: Output current value = single working period current contribution value ÷ pulse output period; Single working period current contribution value = lower limit value of current setting value * working period.

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