CN100579323C - Light emitting device and method for driving the same - Google Patents

Abstract

The present invention relates to a light-emitting device and a driving method thereof. The driving method is to successively drive a first light-emitting diode and a second light-emitting diode to emit light in a first period and a second period respectively. The driving method comprises the following steps: in the first period, output a driving signal with a first duty cycle to drive the first light-emitting diode; and in the first period, output a driving signal with a second duty cycle to drive the first light-emitting diode, wherein the second duty cycle is less than the first duty cycle. The light-emitting device comprises: a power supply circuit outputting a voltage; a transformer having a primary side and a secondary side; a first light-emitting unit electrically connected to the secondary side of the transformer; a second light-emitting unit electrically connected to the secondary side of the transformer; and a transformer switch electrically connected to the transformer.

Description

Light emitting device and driving method thereof

technical field

The invention relates to a light emitting device and a driving method thereof, in particular to a light emitting device with a light emitting diode and a driving method of the light emitting device.

Background technique

Light-emitting diodes are generally made of P-type semiconductors and N-type semiconductors. Due to the advantages of long life, fast lighting speed, high photoelectric conversion efficiency, small size and narrow spectrum, light-emitting diodes made of semiconductor elements have recently received considerable attention. The importance of this has also accelerated the growth of light-emitting diode technology.

Please refer to FIG. 1 , which is a schematic view showing a conventional light emitting device. A light emitting device 1 includes a power supply circuit 11, a transformer 12, a voltage stabilizing capacitor 13, a resonant filter 14, a clamper 15, a plurality of light emitting units 16-18, and a light emitting period control circuit 19, Each light-emitting unit 16-18 includes three light-emitting diodes 161-181 and a switch 162-182 respectively. The power supply circuit 11 is electrically connected to the transformer 12 to provide a voltage V _IN . The transformer 12 converts the voltage V _IN to output a voltage V IN _OUT , the voltage stabilizing capacitor 13 is electrically connected to the transformer 12 to stabilize the voltage V _OUT , the resonant filter 14 is electrically connected to the transformer 12 and filters the voltage V _OUT so as to eliminate high-frequency surges, and each light emitting unit 16-18 is transparently filtered The wave converter 14 is electrically connected to the transformer 12, and the voltage V _OUT drives the LEDs 161-181 of the light-emitting units 16-18 to emit light.

The light-emitting period control circuit 19 is electrically connected to the switches 162, 172 and 182, and controls the switches 162, 172 and 182 to turn on the light-emitting diodes 161, 171, 181 and the transformer 12 during the first period, the second period and the third period respectively, The light emitting diodes 161, 171, 181 are respectively driven by controlling the voltage V _OUT in each period.

The light-emitting diodes 161, 171, 181 are set to emit blue, red, and green light. However, since the rated driving voltages of each light-emitting unit 161, 171, 181 are different, for example, the voltage V _OUT must be reduced to change from driving the light-emitting unit 161. In order to drive the light-emitting unit 171, the clamper 15 is used to consume too much power during the transition, so as to avoid the excessive residual voltage V _OUT driving the light-emitting unit 171 and cause the light-emitting wavelength of the light-emitting unit 171 to shift or affect its service life. In addition, under this structure, the resonant filter 14 and the clamper 15 will also cause additional costs.

Therefore, how to provide a light emitting device and its driving method so as to reduce the residual voltage is one of the current important issues.

It can be seen that the above-mentioned existing light-emitting device and its driving method obviously still have inconveniences and defects in structure and use, and need to be further improved. In order to solve the problems existing in light-emitting devices and their driving methods, relevant manufacturers have tried their best to find solutions, but no suitable design has been developed for a long time, and general products have no suitable structure to solve the above problems. , this is obviously a problem that relevant industry players are eager to solve.

In view of the defects in the above-mentioned existing light-emitting devices and their driving methods, the inventors actively researched and innovated based on years of rich practical experience and professional knowledge in the design and manufacture of such products, and combined with the application of academic theories, in order to create a The new light-emitting device and its driving method can improve the general existing light-emitting device and its driving method, making it more practical. Through continuous research, design, and after repeated trial samples and improvements, the present invention with practical value is finally created.

Contents of the invention

The purpose of the present invention is to overcome the defects of the existing light-emitting device and its driving method, and provide a new light-emitting device and its driving method. The technical problem to be solved is to reduce the residual voltage, so that it is more suitable for practical use. .

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. According to a driving method of a light-emitting device proposed by the present invention, a first light-emitting diode and a second light-emitting diode are sequentially driven to emit light in a first period and a second period respectively, and the driving method includes the following steps: During the period, first output a driving signal with a first duty cycle to drive the first light emitting diode; and during the first period, then output the drive signal with a second duty cycle to drive the first light emitting diode A light emitting diode, wherein the second duty cycle is smaller than the first duty cycle, wherein the average voltage value of the drive signal with the first duty cycle is higher than the average voltage value of the drive signal with the second duty cycle When the driving signal has the second duty cycle, the average voltage value is between the rated driving voltage of the first LED and the rated driving voltage of the second LED.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

The driving method of the aforementioned light emitting device further includes: during the first period, outputting the driving signal with a third duty cycle to drive the first light emitting diode.

The driving method of the aforementioned light emitting device further includes: during the second period, outputting the driving signal with a fourth duty cycle to drive the second light emitting diode.

In the aforementioned driving method of a light emitting device, wherein the average voltage value of the driving signal during the first period is higher or lower than the average voltage value during the second period.

In the aforementioned driving method of the light emitting device, the voltage value of the driving signal in the first period is gradually increased or decreased.

The purpose of the present invention and the solution to its technical problems are also achieved by the following technical solutions. A lighting device according to the present invention includes: a power supply circuit outputting a voltage; a transformer having a primary side and a secondary side, the primary side is electrically connected to the power supply circuit for converting the voltage and outputting a driving signal from the secondary side; a first light emitting unit having a first light emitting diode, the first light emitting diode is electrically connected to the secondary side of the transformer, and is controlled by the driving signal driven to emit light during a first period; a second light emitting unit having a second light emitting diode, the second light emitting diode is electrically connected to the secondary side of the transformer, and is driven by the driving signal to emit light during a first period Two periods of light emission, wherein the first light-emitting unit and the second light-emitting unit are connected in parallel; and a transformer switch is electrically connected to the transformer, and in the first period, successively receives a first duty cycle and a second duty cycle A PWM control signal with a period to control the transformer to output the drive signal with the first duty period and the second duty period, wherein the second duty period is smaller than the first duty period, wherein the drive signal has the The average voltage value of the first duty cycle is higher than the average voltage value of the second duty cycle, and the drive signal has an average voltage value of the second duty cycle between the rated drive voltage of the first light-emitting diode and the rated drive voltage of the first light-emitting diode. Between the rated driving voltage of the second LED.

The purpose of the present invention and its technical problems can also be further realized by adopting the following technical measures.

In the aforementioned light-emitting device, wherein the switch receives the PWM control signal with a third duty cycle in the first period, so as to control the transformer to output the driving signal with the third duty cycle.

In the aforementioned light-emitting device, wherein the transformer switch receives the PWM control signal with a fourth duty cycle for the second period, so as to control the transformer to output the drive signal with the fourth duty cycle.

In the aforementioned light-emitting device, the first light-emitting unit includes: a first switch electrically connected to the first light-emitting diode and turned on during the first period to control the driving signal to drive the first light-emitting diode.

In the aforementioned light-emitting device, the second light-emitting unit includes: a second switch electrically connected to the second light-emitting diode and turned on during the second period to control the driving signal to drive the second light-emitting diode.

In the aforementioned light-emitting device, the rated driving voltage of the first light-emitting diode is higher than the rated driving voltage of the second light-emitting diode.

In the aforementioned light-emitting device, wherein the average voltage value of the driving signal during the first period is higher or lower than the average voltage value during the second period.

In the aforementioned light-emitting device, the first light-emitting unit includes a plurality of first light-emitting diodes connected in series, or the second light-emitting unit includes a plurality of second light-emitting diodes connected in series.

With the above technical solution, the light emitting device and its driving method of the present invention have at least the following advantages:

In the light-emitting device and its driving method according to the present invention, within the first period, the driving signal has a first duty cycle and a second duty cycle successively, and the second duty cycle is shorter than the first duty cycle, so that the first duty cycle and Before the transition in the second period, the average voltage of the driving signal can be properly reduced, thus avoiding that there is still an excessively high voltage in the second period to drive the second light emitting diode.

In summary, the light-emitting device and its driving method of the present invention can effectively reduce the residual voltage, and no similar structural design has been published or used in similar products, so it is indeed innovative, regardless of product structure or function There have been great improvements in technology, great progress in technology, and produced useful and practical effects, and compared with the existing light-emitting devices and their driving methods, they have improved multiple functions, so they are more suitable for practical use. , and has wide application value in the industry, it is a novel, progressive and practical new design.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram showing a conventional light emitting device.

FIG. 2 is a schematic diagram showing a light emitting device according to a preferred embodiment of the present invention.

FIG. 3 is a waveform diagram showing a PWM control signal and a driving signal in a light emitting device according to a preferred embodiment of the present invention.

FIG. 4 is a waveform diagram showing a driving signal in a first period of the light emitting device according to a preferred embodiment of the present invention.

FIG. 5 is another waveform diagram showing a PWM control signal and a driving signal in a light emitting device according to a preferred embodiment of the present invention.

FIG. 6 is another schematic diagram showing a light emitting device according to a preferred embodiment of the present invention.

1: Lighting device 11: Power supply circuit

12: Transformer 13: Stabilizing capacitor

14: Resonant filter 15: Clamper

16, 17, 18: Light-emitting unit 161, 171, 181: Light-emitting diode

162, 172, 182: switch 19: control circuit during lighting

2: Light-emitting device 21: The first light-emitting unit

211 first light-emitting diode 212: switch

22: Second light-emitting unit 221 second light-emitting diode

222: Switch 23: The third light-emitting unit

231 third light-emitting diode 232: switch

24: Power supply circuit 25: Transformer

26: Transformer switch 27: PWM control circuit

28: Control circuit during lighting period 291: Diode

292: capacitor CNT: PWM control signal

S: Drive signal V, V _IN , V _OUT : Voltage

V ₁₁ , V ₁₂ , V ₁₃ : Average voltage values V ₂₁ , V ₂₂ : Average voltage values

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation, structure, characteristics and methods of the light-emitting device and its driving method according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. Its effect is described in detail below.

Please refer to FIG. 2 , which is a schematic diagram showing a light emitting device according to a preferred embodiment of the present invention. A light emitting device 2 includes a first light emitting unit 21, a second light emitting unit 22, a third light emitting unit 23, a power supply circuit 24, a transformer 25, a transformer switch 26, a PWM control circuit 27, a light emitting period The control circuit 28 , a diode 291 , and a capacitor 292 .

The power supply circuit 24 outputs a voltage V. The transformer 25 has a primary side and a secondary side. The primary side is electrically connected to the power supply circuit 24 to convert the voltage V and output a driving signal S. The first light emitting unit 21 , the second light-emitting unit 22, connected in parallel with the third light-emitting unit 23, and electrically connected to the secondary side of the transformer 25, and driven by the driving signal S during a first period, a second period, and a third period respectively And glow. The transformer switch 26 is electrically connected to the transformer 25 and controlled by a PWM control signal CNT.

Please refer to FIG. 3 , which is a waveform diagram showing a PWM control signal and a driving signal in a light emitting device according to a preferred embodiment of the present invention. During the first period, the PWM control signal CNT has a first duty cycle and a second duty cycle successively, the second duty cycle is shorter than the first duty cycle, and the transformer switch 26 controls whether the power supply circuit 24 outputs the voltage V to the transformer 25, so that the driving signal S output by the control transformer 25 corresponds to the PWM control signal CNT, and the driving signal S also has a first duty cycle and a second duty cycle.

Please refer to FIG. 2 again. In this embodiment, the capacitor 292 is connected in parallel with the first light-emitting unit 21, the second light-emitting unit 22 and the third light-emitting unit 23, which is used to stabilize the voltage of the driving signal S. The first light-emitting unit 21. The second light emitting unit 22 and the third light emitting unit 23 are electrically connected to the transformer 25 through a diode 291, and the diode 291 prevents reverse current from driving these light emitting units.

The first light emitting unit 21 includes a first light emitting diode 211 and a switch 212, the first light emitting diode 211 is electrically connected to the transformer 25, and the switch 212 is electrically connected to the first light emitting diode 211; the second light emitting unit 22 includes a second The light emitting diode 221 and a switch 222, the second light emitting diode 221 is electrically connected to the transformer 25, the switch 222 is electrically connected to the second light emitting diode 221; the third light emitting unit 23 includes a third light emitting diode 231 and a switch 232, the second The three LEDs 231 are electrically connected to the transformer 25 , and the switch 232 is electrically connected to the third LED 231 .

The light-emitting period control circuit 28 is electrically connected to the switches 212, 222 and 232, and controls the switches 212, 222 and 232 to be turned on in the first period, the second period and the third period respectively, so as to control the driving signal S to drive in each period. The first LED 211 , the second LED 221 , and the third LED 231 .

The first light emitting diode 211, the second light emitting diode 221, and the third light emitting diode 231 are blue light diodes, red light diodes, and green light diodes respectively, and the rated driving voltage of the first light emitting diode 211 is higher than the rated driving voltage of the second light emitting diode 221. Driving voltage, the rated driving voltage of the second LED 221 is higher than the rated driving voltage of the third LED 231 .

Please refer to FIG. 3 again. In this embodiment, the blue light-emitting diodes are driven during the first period, the red light-emitting diodes are driven during the second period, and the green light-emitting diodes are driven during the third period. For the light-emitting diodes of the driving voltage, the values of the voltage V provided by the power supply circuit 24 during the first period, the second period and the third period are respectively V ₁ , V ₂ and V ₃ , wherein V ₁ is greater than V ₂ , V ₂ is greater than V ₃ , therefore, the transformer 25 converts each corresponding voltage V in each period, so that the average voltage value V ₁ of the driving signal S in the first period is higher than the average voltage value V ₂ in the second period, and in the The average voltage value V ₂ during the second period is higher than the average voltage value V ₃ during the third period.

In addition, if the green light-emitting diode is driven during the first period, the blue light-emitting diode is driven during the second period, and the red light-emitting diode is driven during the third period, the average voltage value _V1 of the driving signal S in the first period is lower than that in the second period. The average voltage value V ₂ during the second period.

In addition, in the first period, the drive signal S has the first duty cycle and the second duty cycle successively, wherein the second duty cycle is smaller than the first duty cycle, and the drive signal S has the average voltage value V ₁₁ of the first duty cycle higher than the average voltage value V ₁₂ with the second duty cycle, and the average voltage value V ₁₂ is between the rated driving voltage of the first light-emitting diode 211 and the rated driving voltage of the second light-emitting diode 221 , thus, in Before the transition between the first period and the second period, the average voltage of the driving signal S will be properly reduced, so that the second light emitting diode 221 can be driven with an excessively high voltage during the second period.

In addition, the transformer switch 26 receives the PWM control signal CNT with a third duty cycle during the first period, so as to control the transformer 25 to output the driving signal S with the third duty cycle. The PWM control signal CNT has a third duty cycle, a first duty cycle, and a second duty cycle successively within the first period, wherein the third duty cycle is shorter than the first duty cycle. The average voltage value V ₁₃ of the drive signal S with the third duty cycle is lower than the average voltage value V ₁₁ with the first duty cycle.

In addition, please refer to FIG. 4 , during the first period, the switch 212 is gradually turned on, so that the voltage value of the driving signal S gradually increases. The switch 212 is gradually turned off, so that the voltage value of the driving signal S decreases gradually. What is particularly noted here is that the duty cycle gradually increases from the third duty cycle to the first duty cycle, and then gradually decreases from the first duty cycle to the second duty cycle.

FIG. 5 is another waveform diagram showing a PWM control signal and a driving signal in a light emitting device according to a preferred embodiment of the present invention. As shown in FIG. 5 , the transformer switch 26 receives the PWM control signal CNT with a fourth duty cycle during the second period, so as to control the transformer 25 to output the driving signal S with the fourth duty cycle.

Please refer to FIG. 5 again. Furthermore, during the second period, the transformer switch 26 further receives a PWM control signal CNT with a fifth duty cycle to control the transformer 25 to output a driving signal S with a fifth duty cycle, wherein the fifth duty The cycle is smaller than the fourth duty cycle, so in the second period, the drive signal S has the fourth duty cycle and the fifth duty cycle respectively, and the average voltage value _V21 of the drive signal S with the fourth duty cycle is higher than that with the fifth duty cycle. The average voltage value V ₂₂ during the duty cycle, and the average voltage value V ₂₂ is between the rated driving voltage of the second light-emitting diode 221 and the rated driving voltage of the third light-emitting diode 23. In this way, during the second period and the first Before the three-period transition, the average voltage of the driving signal S will be appropriately lowered, so that the third light-emitting diode 23 can be driven with an excessively high voltage during the third period.

Please refer to FIG. 6 , which is another schematic diagram showing a light emitting device 2 according to a preferred embodiment of the present invention. The difference from that shown in FIG. 2 is that each first light-emitting unit 21 includes a plurality of first light-emitting diodes 211 connected in series, the second light-emitting unit 22 includes a plurality of second light-emitting diodes 221 connected in series, and the third light-emitting unit 23 includes a plurality of The second LED 231 is connected in series. And the light emitting device 2 includes a plurality of first light emitting units 21 , second light emitting units 22 , and third light emitting units 23 , and these light emitting units are arranged into a light emitting array.

In summary, according to the light-emitting device and its driving method of the present invention, within the first period, the driving signal has a first duty cycle and a second duty cycle successively, and the second duty cycle is shorter than the first duty cycle, so that Before the transition between the first period and the second period, the average voltage of the driving signal can be properly reduced, so that the second light-emitting diode is still driven by an excessively high voltage during the second period.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments by the technical essence still belong to the scope of the technical solution of the present invention.

Claims (13)

1. A driving method for a light emitting device, characterized in that sequentially driving a first light emitting diode and a second light emitting diode to emit light in a first period and a second period respectively, the driving method comprises the following steps: During the first period, firstly output a driving signal with a first duty cycle to drive the first light emitting diode; and During the first period, then outputting the drive signal with a second duty cycle to drive the first light emitting diode, wherein the second duty cycle is shorter than the first duty cycle, Wherein the average voltage value of the drive signal with the first duty cycle is higher than the average voltage value of the drive signal with the second duty cycle, the drive signal has an average voltage value with the second duty cycle Between the rated driving voltage of the first LED and the rated driving voltage of the second LED. 2. The driving method according to claim 1, further comprising: During the first period, the driving signal with a third duty cycle is output to drive the first light emitting diode. 3. The driving method according to claim 1, further comprising: During the second period, the driving signal with a fourth duty cycle is output to drive the second LED. 4. The driving method as claimed in claim 1, wherein the average voltage value of the driving signal during the first period is higher or lower than the average voltage value during the second period. 5. The driving method as claimed in claim 1, wherein the voltage value of the driving signal in the first period increases or decreases gradually. 6. A lighting device, characterized by comprising: A power supply circuit that outputs a voltage; A transformer has a primary side and a secondary side, the primary side is electrically connected to the power supply circuit to convert the voltage and output a driving signal from the secondary side; a first light emitting unit having a first light emitting diode, the first light emitting diode is electrically connected to the secondary side of the transformer, and is driven by the driving signal to emit light during a first period; A second light emitting unit has a second light emitting diode, the second light emitting diode is electrically connected to the secondary side of the transformer, and is driven by the driving signal to emit light in a second period, wherein the first light emitting the unit is connected in parallel with the second light emitting unit; and A transformer switch, electrically connected to the transformer, within the first period, successively receives a PWM control signal with a first duty cycle and a second duty cycle, so as to control the output of the transformer with the first duty cycle and the second duty cycle the driving signal of the second duty cycle, wherein the second duty cycle is less than the first duty cycle, Wherein the average voltage value of the driving signal with the first duty cycle is higher than the average voltage value of the second duty cycle, and the average voltage value of the drive signal with the second duty cycle is between the first LED between the rated driving voltage of the second LED and the rated driving voltage of the second LED. 7. The lighting device as claimed in claim 6, wherein the switch receives the PWM control signal with a third duty cycle during the first period to control the transformer to output the PWM signal with the third duty cycle the drive signal. 8. The light emitting device as claimed in claim 6, wherein the transformer switch receives the PWM control signal with a fourth duty cycle for the second period, so as to control the transformer to output the PWM signal with the fourth duty cycle the drive signal. 9. The lighting device according to claim 6, wherein the first lighting unit comprises: A first switch is electrically connected to the first light emitting diode, and is turned on during the first period to control the driving signal to drive the first light emitting diode. 10. The light emitting device according to claim 9, wherein the second light emitting unit comprises: A second switch is electrically connected to the second light emitting diode, and is turned on during the second period to control the driving signal to drive the second light emitting diode. 11. The light emitting device as claimed in claim 10, wherein the rated driving voltage of the first LED is higher than the rated driving voltage of the second LED. 12. The light emitting device as claimed in claim 6, wherein the average voltage value of the driving signal during the first period is higher or lower than the average voltage value during the second period. 13. The light emitting device according to claim 6, wherein the first light emitting unit comprises a plurality of first light emitting diodes connected in series, or the second light emitting unit comprises a plurality of second light emitting diodes connected in series.

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