TW201705819A - Light emitting diode linear light modulator with temperature compensation - Google Patents

Abstract

A light emitting diode (LED) linear light modulator with temperature compensation includes a comparing module, a timing processing module, an LED module and a temperature compensating current control module. The comparing module compares an analog input signal with a triangular wave sampling signal to generate a pulse width modulation (PWM) signal. The PWM signal is inputted into the timing processing module and converted to a digital signal. The temperature compensating current control module, electrically connected to the LED module and the timing processing module, includes a plurality of low-temperature correlated linear current units and a switching switch, and controls a current amount passing through the LED module to generate a low-temperature correlated linear current. Thus, the color temperature of an LED is prevented from drifting with a change in the ambient temperature.

Description

Temperature compensated LED dimmer linear dimmer

The invention relates to a light-emitting diode dimmer, in particular to a temperature-compensated light-emitting diode linear dimmer.

A wide variety of light sources are used in our lives, such as incandescent bulbs, fluorescent lamps, light-emitting diodes, etc. Among them, light-emitting diodes have high efficiency, long life, are not easily damaged, and have fast response and reliability. The advantages of higher traditional light sources are widely used in various fields.

The light-emitting diode dimming method is mainly divided into two types: a linear adjustment and a pulse width modulation, and a pulse width modulation method, such as "LED driving device with pulse width modulation" of the European Patent Publication No. EP 1814365, which includes a pulse wave. The width modulation control unit and a light emitting diode driving circuit divide the time of the light emission in the pulse width modulation period of the pulse width modulation control unit into a main illumination period and a secondary illumination period, and then the main illumination period It is cut into several small periods and dispersed throughout the pulse width modulation period, which improves the number of times of illumination and the update rate, and avoids the phenomenon of discontinuity or flickering of the picture.

Although it solves the phenomenon that the picture is discontinuous or flickering, the principle of pulse width modulation is to make the switch switch quickly, and the continuous linear light is generated by the phenomenon of persistence of the human eye vision, and the update rate can certainly prevent the human eye from perceiving. The problem of flickering, but fundamentally, the rapid switching of the switch will cause a large current to flow into the light-emitting diode instantaneously, which may reduce the service life of the light-emitting diode, and when the ambient temperature changes, the semiconductor component of the circuit will The input current is changed, and the color temperature of the light-emitting diode is shifted. Therefore, how to make the color temperature of the light-emitting diode not drift with the change of the ambient temperature is a goal that the industry strives.

The main object of the present invention is to solve the problem that the color temperature of the light-emitting diode drifts as the ambient temperature changes.

A secondary object of the present invention is to solve the problem that the switch quickly switches to cause a large current to flow into the light-emitting diode instantaneously, thereby reducing the service life of the light-emitting diode.

To achieve the above objective, the present invention provides a temperature compensated LED dimmer linear dimmer comprising a comparison module, a timing processing module, a light emitting diode module and a temperature compensation current control module. The comparison module compares an analog input signal with a triangular wave sampling signal to generate a pulse width modulation signal, and the timing processing module receives the pulse width modulation signal and converts it into a digital signal, the temperature compensation The current control module is electrically connected to the LED module and the timing processing module, and includes a plurality of low temperature related linear current units connected in parallel with each other, and an electrical connection to the timing processing module, the light emitting diode a switching module of the polar body module and the low temperature-dependent linear current units, each of the low temperature-dependent linear current units each having a positive temperature-dependent linear current portion that becomes larger as the temperature increases, and a smaller as the temperature increases a negative temperature-dependent linear current portion for generating a low temperature-dependent linear current, wherein the timing processing module controls the electrical conduction between each of the low temperature-dependent linear current units and the light-emitting diode module by the switch The amount of current flowing through the light emitting diode module is controlled.

In summary, the present invention has the following features:

1. By setting the low temperature dependent linear current units, a low temperature dependent linear current with very low temperature dependence is generated, so that the light emitting diode does not drift with changes in ambient temperature.

Second, the timing switch module controls the switch, and then controls the amount of current flowing through the LED module to increase the service life of the LED module.

The detailed description and technical content of the present invention will now be described as follows:

Referring to FIG. 1 and FIG. 2, the present invention provides a temperature compensated LED dimmer linear dimmer comprising a comparison module 10, a timing processing module 20, and a digital low pass filter. The module 50, an LED module 30, an independent voltage source 60, and a temperature compensation current control module 40. The comparison module 10 compares a analog input signal 12 with a triangular wave sampling signal 11 to generate a pulse width modulation signal 13 , and the pulse width modulation signal 13 is further input to the timing processing module 20 . The timing processing module 20 further includes a delay unit 22, an adding unit 23, and a latching unit 24, and the pulse width modulation signal 13 is delayed by the delay unit 22 to generate a plurality of timing signals 25, and the adding unit 23 The timing signals 25 are added to generate a plurality of timing addition signals 26, and the timing addition signals 26 are synchronized by the latch unit 24 to form a digital signal 21 output.

The independent voltage source 60 provides the voltage required by the LED module 30. The digital low-pass filter module 50 is electrically connected between the timing processing module 20 and the temperature compensation current control module 40. The digital signal 21 that receives a smaller number of bits is converted into a digital signal 51 of a greater number of bits and output to the temperature compensation current control module 40. The temperature compensation current control module 40 includes a plurality of parallel lines. The low temperature related linear current unit 41 and a switch 42 are electrically connected to the digital low pass filter module 50, the LED module 30 and the low temperature related linear current units 41, The number of bits of the digital signal 51 corresponds to the number of the low temperature dependent linear current units 41, and the switch 42 is used to control the low temperature dependent linear current unit 41 and the LED module 30. Electrically conducting, thereby controlling the amount of current flowing through the LED module 30.

In this embodiment, the temperature compensation current control module 40 further includes a voltage buffer unit 43 connected between the LED module 30 and the switch 42 for stabilizing the independent voltage source 60. The voltage of the switch 42 can be operated to control the electrical conduction between the LED module 30 and the low temperature related linear current units 41.

Referring to FIG. 3, the temperature compensation current control module 40 further has a positive temperature dependent current generating unit 44 and a negative temperature related current generating unit 45. The positive temperature dependent current generating unit 44 includes a first The positive temperature-dependent current generating unit 441 and the second positive temperature-dependent current generating unit 442, the first positive temperature-dependent current generating unit 441 and the second positive temperature-dependent current generating unit 442 are connected in parallel and electrically connected to a voltage source 46. And each of the first P-type transistor 443, a second P-type transistor 444, and a first N-type transistor 445. The source of the first P-type transistor 443 is electrically connected to the voltage source 46. The drain of the first P-type transistor 443 is electrically connected to the source of the second P-type transistor 444 and the gate of the first P-type transistor 443, and the second P-type transistor 444 The pole is electrically connected to the drain and the gate of the first N-type transistor 445, the source of the first N-type transistor 445 is grounded, and the second P-type of the first positive temperature-dependent current generating portion 441 The gate of the crystal 444 is electrically connected to a first voltage input terminal 446, and the second positive Gate electrically correlation of the second current-generating portion 442 of the P-type transistor 444 is connected to a second voltage of the input terminal 447.

The negative temperature-dependent current generating unit 45 includes a first negative temperature-dependent current generating portion 451 and a second negative temperature-related current generating portion 452, and the first negative temperature-related current generating portion 451 and the second negative temperature-related current generating portion The portions 452 are connected in parallel to each other and electrically connected to the voltage source 46, and each includes a third P-type transistor 453 and a second N-type transistor 454. The source of the third P-type transistor 453 is electrically connected to the source. a voltage source 46, the drain of the third P-type transistor 453 is electrically connected to the drain of the second N-type transistor 454 and the gate of the third P-type transistor 453, the second N-type transistor The source of the 454 is grounded, and the gate of the second N-type transistor 454 of the first negative temperature-dependent current generating portion 451 is electrically connected to a third voltage input terminal 455. The second negative temperature-dependent current generating portion 452 The gate of the second N-type transistor 454 is electrically connected to a fourth voltage input terminal 456.

Referring to FIG. 4A to FIG. 4C, the voltage input by the first voltage input terminal 446 and the second voltage input terminal 447 is controlled. When the gate source voltage (Vgs) is greater than a certain threshold value, The first positive temperature-dependent current generating portion 441 generates a first positive nonlinear current 711. When the gate source voltage (Vgs) is less than a certain threshold, the second positive temperature-dependent current generating portion 442 generates a second A positive nonlinear current 712, which is complementary to the second positive nonlinear current 712, forms a positive temperature dependent linear current 71. Similarly, the voltage input by the third voltage input terminal 455 and the fourth voltage input terminal 456 is controlled, and when the gate source voltage (Vgs) is greater than a certain threshold, the first negative temperature related current is generated. The portion 451 generates a first negative nonlinear current 721. When the gate source voltage (Vgs) is less than a certain threshold, the second negative temperature-dependent current generating portion 452 generates a second negative nonlinear current 722. The first negative nonlinear current 721 is complementary to the second negative nonlinear current 722 to form a negative temperature dependent linear current 72. Finally, the positive temperature-dependent linear current 71 is complementary to the negative temperature-dependent linear current 72 to form a low-temperature-dependent linear current 70, so that the on-current of the LED module 30 does not change with the ambient temperature. drift.

Referring to FIG. 5A and FIG. 5B again, it is an experimental data diagram of the present invention, wherein the ordinate is the amount of current flowing, the abscissa is the time of dimming, and the temperature is between -20 ° C and Experiment was carried out between 120 ° C. "Fig. 5A" is an experiment in the case where the temperature compensation current control module 40 is not provided, and a temperature uncompensated line segment 81 of -20 ° C is obtained at a temperature of -20 ° C, and When the temperature is 120 ° C, a 120 ° C temperature uncompensated line segment 82 is obtained, and it is known that the temperature affects the current amount, causing the color temperature of the LED module 30 to drift; "FIG. 5B" is provided with the temperature compensation current control. Experiments were carried out in the case of module 40, and the results measured at temperatures -20 ° C to 120 ° C almost completely overlap and are represented by temperature compensation line segment 83.

In addition, the low temperature-dependent linear current units 41 may respectively include at least two current mirrors 413, which are generated by a positive temperature-dependent linear current portion 411 that generates a current proportional to temperature and inversely proportional to temperature. The negative temperature dependent linear current portion 412 of the current is formed and mirrors the current of the positive temperature dependent current generating unit 44 and the negative temperature dependent current generating unit 45. The switch 42 has a plurality of N-type switching transistors 421 respectively connected to the low-temperature-dependent linear current units 41. The gates of the N-type switching transistors 421 are respectively connected to the digital low-pass filter module 50. The drain is connected to the voltage buffer unit 43 and is connected to the LED module 30. The voltage buffer unit 43 is configured to stabilize the voltage provided by the independent voltage source 60. The sources are respectively connected to the low voltage. The temperature-dependent linear current unit 41 controls the N-type switching transistors 421 to control the electrical conduction between the LED module 30 and the low temperature-dependent linear current units 41.

It should be noted that the amount of current in the low temperature dependent linear current units 41 may be different. In the embodiment, each of the low temperature related linear current units 41 may be through the N type switching transistors 421. The adjustment, and the power distribution flow is incremented by ¹ , 2 ¹ , 2 ² , 2 ³ ... to control the amount of current of the low temperature dependent linear current units 41, so that the light emitting diode can receive a linear current And adjusting the brightness of the output illumination. For example, when it is required to output five times of current, the digital signal 51 output by the digital low-pass filter module 50 can be output as 0-0-0-0-0-1- 0-1, the switch 42 is controlled to turn on the low-temperature-dependent linear current unit 41 of one current and four times, and then add up to obtain the required five times of current. The method of switching the width of the pulse wave as in the prior art is to control the time between the minimum current and the maximum current, so that the service life of the LED module 30 can be increased.

In summary, the present invention has the following features:

1. The positive temperature-dependent current generating unit generates the positive temperature-dependent linear current, the negative temperature-dependent current generating unit generates the negative temperature-dependent linear current, and the positive temperature-dependent linear current is complementary to the negative temperature-dependent linear current And forming a low temperature-dependent linear current, so that the light-emitting diode module does not drift with changes in ambient temperature.

2. By setting the amount of current in the low temperature related linear current units to be different, increasing from ¹ , 2 ¹ , 2 ² , 2 ³ ..., and then using the N type switching transistors to control the light emitting The electrical connection between the polar body module and the low temperature related linear current units enables the LED to be accurately linearly adjusted.

3. The amount of current in the low-temperature-dependent linear current units is different, so that when the N-type switching transistors are switched, the current amount is not switched between the minimum current and the maximum current, and the light-emitting diode can be increased. The service life of the body module.

Therefore, the present invention is highly progressive and conforms to the requirements of the invention patent application, and the application is made according to law, and the praying office grants the patent as soon as possible.

The present invention has been described in detail above, but the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the scope of the invention. That is, the equivalent changes and modifications made by the scope of the present application should remain within the scope of the patent of the present invention.

10‧‧‧Comparative Module
11‧‧‧ triangular wave sampling signal
12‧‧‧ analog input signal
13‧‧‧ Pulse width modulation signal
20‧‧‧Time Processing Module
21‧‧‧ digital signal
22‧‧‧Delay unit
23‧‧‧Addition unit
24‧‧‧Lock unit
25‧‧‧ Timing signal
26‧‧‧Timed addition signal
30‧‧‧Lighting diode module
40‧‧‧Temperature Compensation Current Control Module
41‧‧‧Low temperature related linear current unit
411‧‧‧Positive temperature dependent linear current section
412‧‧‧Negative temperature-dependent linear current section
413‧‧‧current mirror
42‧‧‧Toggle switch
421‧‧‧N type switching transistor
43‧‧‧Voltage buffer unit
44‧‧‧Positive temperature dependent current generating unit
441‧‧‧First positive temperature dependent current generation unit
442‧‧‧Second positive temperature dependent current generation unit
443‧‧‧First P-type transistor
444‧‧‧Second P-type transistor
445‧‧‧First N-type transistor
446‧‧‧First voltage input
447‧‧‧second voltage input
45‧‧‧Negative temperature-dependent current generating unit
451‧‧‧First negative temperature dependent current generation unit
452‧‧‧Second negative temperature-dependent current generation unit
453‧‧‧ Third P-type transistor
454‧‧‧Second N-type transistor
455‧‧‧ third voltage input
456‧‧‧ fourth voltage input
46‧‧‧voltage source
50‧‧‧Digital Low Pass Filter Module
51‧‧‧ digital signal
60‧‧‧Independent voltage source
70‧‧‧Low temperature related linear current
71‧‧‧Positive temperature dependent linear current
711‧‧‧First positive nonlinear current
712‧‧‧Second positive nonlinear current
72‧‧‧Negative temperature-dependent linear current
721‧‧‧First negative nonlinear current
722‧‧‧Second negative nonlinear current
81‧‧‧-20°C temperature uncompensated line segment
82‧‧‧120°C temperature uncompensated line segment
83‧‧‧Temperature compensation line segment

FIG. 1 is a schematic diagram of a unit configuration according to a preferred embodiment of the present invention. 2 is a block diagram of a timing processing module unit according to a preferred embodiment of the present invention. 3 is a circuit diagram of a temperature compensation current control module according to a preferred embodiment of the present invention. 4A is a schematic diagram of a positive temperature dependent linear current of the present invention. 4B is a schematic diagram of a negative temperature dependent linear current of the present invention. 4C is a schematic diagram of a low temperature dependent linear current of the present invention. FIG. 5A is a data diagram of a temperature compensation current control module in which the present invention is not provided. Figure 5B is a data diagram of a temperature compensated current control module of the present invention.

10‧‧‧Comparative Module

11‧‧‧ triangular wave sampling signal

12‧‧‧ analog input signal

13‧‧‧ Pulse width modulation signal

20‧‧‧Time Processing Module

21‧‧‧ digital signal

30‧‧‧Lighting diode module

40‧‧‧Temperature Compensation Current Control Module

41‧‧‧Low temperature related linear current unit

42‧‧‧Toggle switch

43‧‧‧Voltage buffer unit

50‧‧‧Digital Low Pass Filter Module

51‧‧‧ digital signal

60‧‧‧Independent voltage source

Claims (7)

A temperature compensated LED dimmer linear dimmer comprising: a comparison module for comparing a type of input signal with a triangular wave sampling signal to generate a pulse width modulation signal; a timing processing module for converting a wave width modulation signal into a digital signal; a light emitting diode module; and a temperature compensation current control mode electrically connected to the light emitting diode module and the timing processing module The group includes a plurality of low temperature-dependent linear current units connected in parallel with each other, and a switch electrically connected to the timing processing module, the light emitting diode module and the low temperature related linear current units, and the low The temperature-dependent linear current units each include a positive temperature-dependent linear current portion that becomes larger as the temperature increases, and a negative temperature-dependent linear current portion that becomes smaller as the temperature increases to generate a low temperature-dependent linear current. The switch controls the electrical conduction between each of the low temperature-dependent linear current units and the LED module by the switch, thereby controlling the flow through the The amount of current in the LED module. The temperature-compensated LED diode dimmer according to claim 1, further comprising a digital low-pass electrically connected between the timing processing module and the temperature compensation current control module. The filter module converts the digital signal that receives a smaller number of bits into a digital signal with a greater number of bits, and the number of bits of the digital signal corresponds to the number of the low temperature dependent linear current units. The temperature-compensated light-emitting diode linear dimmer of claim 2, wherein the temperature-compensating current control module further comprises a connection between the light-emitting diode module and the switch a voltage buffer unit; the switch has a plurality of N-type switch transistors respectively connected to the low temperature-dependent linear current units, and the gates of the N-type switch transistors are respectively connected to the digital low-pass filter module, and each of the switches The poles are connected to the voltage buffer unit, and the respective sources are respectively connected to the low temperature related linear current units, and the digital signals control the N type switch transistors to control the LED module and the low temperature Electrical conduction of the associated linear current unit. The temperature-compensated light-emitting diode linear dimmer according to claim 1, wherein the timing processing module further comprises a delay unit, an adding unit and a latch unit, wherein the pulse width modulation The signal is delayed by the delay unit to generate a plurality of timing signals, and the adding unit adds the timing signals to generate a plurality of timing addition signals, and then synchronizes the timing addition signals via the latch unit. The temperature compensated LED diode dimmer according to claim 1, wherein the temperature compensation current control module further comprises a positive temperature dependent current generating unit and a negative temperature related current generating unit. The low temperature dependent linear current units each include at least two current mirrors, the at least two current mirrors being the positive temperature dependent linear current portion and the negative temperature dependent linear current portion, mirroring the positive temperature dependent current generating unit and the The current of the negative temperature dependent current generating unit. The temperature-compensated light-emitting diode linear dimmer according to claim 5, wherein the positive temperature-dependent current generating unit comprises a first positive temperature-dependent current generating portion and a second positive temperature-dependent current generating portion. The first positive temperature-dependent current generating unit and the second positive temperature-dependent current generating unit are connected in parallel and electrically connected to a voltage source, and each includes a first P-type transistor, a second P-type transistor, and a first N-type transistor, the source of the first P-type transistor is electrically connected to the voltage source, and the drain of the first P-type transistor is electrically connected to the source of the second P-type transistor And a gate of the first P-type transistor, a drain of the second P-type transistor is electrically connected to a drain and a gate of the first N-type transistor, and a source of the first N-type transistor Grounding, the gate of the second P-type transistor of the first positive temperature-dependent current generating portion is electrically connected to a first voltage input end, and the second P-type transistor of the second positive temperature-dependent current generating portion The gate is electrically connected to a second voltage input terminal, and the first voltage input is utilized The voltage input to the second voltage input terminal controls the first positive temperature-dependent current generating portion and the second positive temperature-dependent current generating portion to generate a first positive nonlinear current and a second positive nonlinear current, respectively And the first positive nonlinear current is complementary to the second positive nonlinear current to form a positive temperature dependent linear current. The temperature-compensated light-emitting diode linear dimmer according to claim 5, wherein the negative temperature-related current generating unit comprises a first negative temperature-dependent current generating portion and a second negative temperature-dependent current generating portion. The first negative temperature-dependent current generating portion and the second negative temperature-dependent current generating portion are connected in parallel and electrically connected to a voltage source, and each includes a third P-type transistor and a second N-type transistor. The source of the third P-type transistor is electrically connected to the voltage source, and the drain of the third P-type transistor is electrically connected to the drain of the second N-type transistor and the third P-type transistor a gate of the second N-type transistor, the gate of the second N-type transistor of the first negative temperature-dependent current generating portion is electrically connected to a third voltage input terminal, the second negative The gate of the second N-type transistor of the temperature-dependent current generating portion is electrically connected to a fourth voltage input terminal, and the voltage is controlled by the voltage input from the third voltage input terminal and the fourth voltage input terminal to make the first negative Temperature dependent current generating portion and the second negative temperature The degree-dependent current generating portion generates a first negative nonlinear current and a second negative nonlinear current, respectively, and the first negative nonlinear current is complementary to the second negative nonlinear current to form a negative temperature-dependent linear current.