Patent Grant
8779682
This application claims the priority of Korean Patent Application No. 10-2011-0057378 filed on Jun. 14, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an illumination driving apparatus capable of using a dimming-adjusted input power.
2. Description of the Related Art
A light emitting device (LED) indicates a semiconductor device capable of implementing various colors of light through alight emitting source using a compound semiconductor made of a material such as gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), gallium nitride (GaN), and indium gallium phosphide (InGaP). This type of light emitting device has rapidly replaced an existing illumination fixture due to advantages such as excellent monochromatic peak wavelength, excellent light efficiency, a small size, environmental friendliness, low power consumption, and the like.
In most of light emitting device driving circuits according to the related art, a scheme of rectifying commercial alternating current (AC) power and then supplying a constant current to the light emitting device by using a converter such as a flyback converter, or the like, has been used. These driving apparatuses need to have compatibility such that they may be used in an existing illumination fixture using a Triac dimmer, or the like. To this end, there is a scheme of detecting and averaging an output voltage of a Triac dimmer and using the averaged output voltage for power conversion.
However, the scheme according to the related art may not accurately detect a degree to which an input AC power is dimmed due to an error in a process of detecting and averaging a voltage, such that it may not drive the light emitting device so as to satisfy requirements of a user.
An aspect of the present invention provides an illumination driving apparatus capable of accurately detecting a degree to which an alternating current (AC) power is dimmed in a Triac dimmer to thereby drive a light emitting device while reflecting the dimming degree.
According to an aspect of the present invention, there is provided an illumination driving apparatus including: a rectifying unit rectifying a phase-controlled waveform of an alternating current (AC) power; a comparing unit comparing an output waveform of the rectifying unit with a first voltage according to a preset reference clock; a reference voltage generating unit generating a reference voltage corresponding to the number of high signals higher than the first voltage among outputs of the comparing unit during one cycle of the output waveform; and a pulse width modulation (PWM) signal generating unit generating a PWM signal from the reference voltage and a feedback voltage.
The reference voltage generating unit may include a shift register sequentially storing the outputs of the comparing unit output according to the reference clock; a register storing data corresponding to one cycle of the output waveform when the data is stored in the shift register; and a voltage generating unit generating the reference voltage based on a value of the data stored in the register.
According to another aspect of the present invention, there is provided an illumination driving apparatus including: a rectifying unit rectifying a phase-controlled waveform of an alternating current (AC) power; a comparing unit comparing an output waveform of the rectifying unit with a first voltage according to a preset reference clock; a reference voltage generating unit calculating the number of high signals higher than the first voltage among outputs of the comparing unit during one cycle of the output waveform when one of the high signals is initially applied during one cycle of the output waveform and then generating a reference voltage corresponding to the number of the high signals; and a pulse width modulation (PWM) signal generating unit generating a PWM signal from the reference voltage and a feedback voltage.
The reference voltage generating unit may include a shift register sequentially storing the outputs of the comparing unit outputted according to the reference clock; a detecting unit detecting that a high signal is initially stored in the shift register during one cycle of the output waveform; a register storing data of the shift register when the high signal is initially detected in the detecting unit and storing bits after a position at which the high signal is detected as being high; and a voltage generating unit generating the reference voltage based on a value of the data stored in the register.
The reference voltage generating unit may include a shift register sequentially storing the outputs of the comparing unit output according to the reference clock; a detecting unit detecting that one of the high signals is initially stored in the shift register during one cycle of the output waveform; a register storing data of the shift register when one of the high signals is initially detected in the detecting unit; and a voltage generating unit generating the reference voltage based on a value of the data stored in the register, the shift register regarding all remaining outputs of the comparing part as high signals during one cycle of the output waveform when the detecting unit detects that one of the high signals is initially stored.
In the aspects of the present invention, the illumination driving apparatus may further include a clock generating unit generating the reference clock and a pulse indicating that one cycle of the output waveform has ended.
The reference clock may have a cycle corresponding to a value obtained by dividing one cycle of the output waveform by an integer.
The illumination driving apparatus may further include a Triac dimmer controlling a phase of the AC power; a DC/DC converting unit converting an output level of the rectifying unit according to the PWM signal; a plurality of light emitting diodes connected to an output terminal of the DC/DC converting unit; and a feedback voltage unit generating the feedback voltage from an output voltage of the DC/DC converting unit.
The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
The present invention should not be seen as being limited to the embodiments set forth herein and the embodiments may be used to assist in understanding the technical idea of the present invention. Like reference numerals designate like components having substantially the same constitution and function in the drawings of the present invention.
Referring to
The Triac dimmer 500 may receive a commercial alternating current (AC) power and phase-control a waveform of the AC power. Here, the Triac dimmer 500, which is an existing illumination fixture, may be embedded in a wall, or the like, of a building.
The rectifying unit 100 may full-wave rectify the AC waveform phase-controlled in the Triac dimmer 500. Here, the rectifying unit 100 may be formed of a bridge diode.
The DC/DC converting unit 600 may convert an output of the rectifying unit 100 into a predetermined voltage level. Here, the DC/DC converting unit 600 may be formed of a flyback converter as shown in
The light emitting diode 700 may receive a output voltage having the voltage level controlled in the DC/DC converting unit 600 to thereby be operated as a light source. Although
The feedback voltage unit 800 may generate a feedback voltage from the output voltage of the DC/DC converting unit 600. Information regarding this feedback voltage may be transferred to a primary side of the DC/DC converting unit 600 through a photocoupler.
The PWM signal generating unit 400 may generate a PWM signal for controlling a switch of the DC/DC converting unit 600 from the feedback voltage and a reference voltage. Here, the PWM signal generating unit 400 may generate the PWM signal through an error amplifier (not shown) comparing the feedback voltage and the reference voltage to thereby amplify an error and a comparator (not shown) comparing an output of the error amplifier and a triangular wave generated in a triangular wave generator (not shown).
Therefore, in order to allow a voltage or a current supplied to the light emitting diode 700 to be constant and satisfy a dimming level required by a user, the reference voltage inputted to the PWM signal generating unit 400 needs to accurately reflect dimming information.
The comparing unit 200 may compare a waveform Vin of the output (“output waveform Vin”) from the rectifying unit 100 and a preset first voltage VLV. Here, the comparing unit 200 may perform the comparison according to reference clocks. That is, describing an operation of the comparing unit 200 based on one cycle of the output waveform Vin of the rectifying unit 100, the comparing unit 200 compares the output waveform Vin of the rectifying unit 100 and the first voltage VLV in terms of the number of reference clocks generated during one cycle, and outputs results of the comparison. Here, the first voltage VLV may be set to a value significantly lower than that of a maximum peak (for example, 1/100 of the maximum peak) of the output waveform Vin from the rectifying unit 100.
The reference voltage generating unit 300 may generate a reference voltage corresponding to the number of high signals higher than the first voltage VLV among outputs of the comparing unit 200 during one cycle of the output waveform Vin of the rectifying part 100. A detailed description of the reference voltage generating unit 300 will be provided in a description of
Referring to
The comparing unit 200 may compare the first voltage VLV and the output waveform Vin from the rectifying unit 100 according to a reference clock Clk and output a result of the comparison to the shift register 310a, as described above in the description of
Therefore, since the comparing unit 200 performs the comparison in a high signal period of the reference clock Clk, it may sequentially output 0, 0, 1, 1, 1, and 1 bit by bit during one cycle of the output waveform of the rectifying unit 100, as shown in
Again referring to
In addition, the shift register 310a may receive from the clock generating unit 340 to be described below, the reference clock Clk and a pulse EOF indicating that one period of the output waveform of the rectifying unit 100 has ended. The shift register 310a may sequentially transfer and store data outputed from the comparing unit 200 according to the reference clock Clk, and may be reset when it receives the pulse EOF.
In the case in which data corresponding to one cycle of the output waveform of the rectifying unit 100 is stored in the shift register 310a, the register 320a may store the data as it is. Similar to the shift register 310a, the register 320a may also receive the pulse (EOF) and may be reset according to the pulse (EOF).
The clock generating unit 340a may generate the reference clock Clk supplied to the shift resistor 310a and the comparing unit 200 and having a predetermined cycle. In addition, the clock generating unit 340a may generate the pulse EOF indicating that one cycle of the output waveform of the rectifying unit 100 supplied to the shift register 310a and the register 320a has ended. Here, the clock generating unit 340a may include a crystal oscillator, or the like.
The voltage generating unit 330a may generate a reference voltage corresponding to the number of 1's among data stored in the register 320a. Therefore, the generated reference voltage may include accurate information dimmed in the Triac dimmer 500. In addition, when the reference voltage is generated, a memory for a lookup table, or the like, is not required.
Referring to
A clock generating unit 340b may generate the reference clock Clk and the pulse (EOF) indicating that one cycle of the output waveform of the rectifying unit 100 has ended. The reference clock Clk and the pulse EOF may be synchronized with the output waveform of the rectifying unit 100. More specifically, an initial cycle of the output waveform of the rectifying unit 100 is compared through the comparing unit 200, and a point at which the output waveform of the rectifying unit initially changes from 1 to 0 is detected in the detecting unit 350. When the above-mentioned operation is repeated in the next cycle, information regarding one cycle of the output waveform of the rectifying unit 100 may be obtained. The reference clock Clk and the pulse EOF may be synchronized with the output waveform of the rectifying unit 100 using this information.
The detecting unit 350 may detect information in which a “1” is initially stored by checking bits sequentially inputted to the shift register 310b. This detected information may be provided to the shift register 310b or a register 320b.
When information in which a “1” is initially stored is provided from the detecting unit 350 to the shift register 310b, the shift register 310b may regard all bits to be subsequently stored as 1 and provide date to the register 320b.
Alternatively, when information in which a “1” is initially stored in the detecting unit 350 is provided from the detecting unit 350 to the register 320b, the register 320b may store a combination of 0 and 1 based on this information.
The voltage generating unit 330b may generate the reference voltage corresponding to the number of 1's among data stored in the register 320b, similar to the description of
That is, the reference voltage generating unit 300 shown in
As set forth above, the illumination driving apparatus according to the embodiments of the present invention may accurately detect the degree to which the AC power is dimmed to thereby maintain compatibility with the existing illumination fixture while driving the light emitting device so as to satisfy the requirements of a user. In addition, the illumination driving apparatus according to the embodiments of the present invention may rapidly detect the dimming and reflect the detected dimming in the light emitting device.
While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
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| 10-2011-0057378 | Jun 2011 | KR | national |
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