# US 2012/0074866 A1 · Lighting apparatus and control method thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2012/0074866 A1 - Document ID: US20120074866A1 - Status: Published application - Kind: A1 - Application number: 13/046,165 - Filed: 2011-03-11 - Published: 2012-03-29 - Earliest claimed: 2010-09-25 - Assignees: Delta Electronics, Inc. - Inventors: Wei-Qiang ZHANG; Li-Zhi Xu; Qi Zhang; Jian-Ping Ying - Web page: https://patentgrep.com/patent/US20120074866A1 ## CPC - H05B 45/44: with an active control inside an LED matrix - H05B 45/3725: Switched mode power supply [SMPS] - H05B 45/375: using buck topology - H05B 45/38: using boost topology - H05B 45/385: using flyback topology - H05B 45/39: Circuits containing inverter bridges - Y02B 20/30: Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A lighting apparatus includes a lighting unit, a converting circuit, a sensing circuit, and a current control circuit. The lighting unit includes at least one light emitting diode and a switching device connected with each other in series. The converting circuit has an output end electrically connected to the lighting unit for driving it. The sensing circuit includes a sensing element capable of indirectly detecting the current flowing through the light emitting diode and outputting a feedback signal. The current control circuit receives a reference current, the feedback signal and a dimming command, and sends a dimming control signal to the lighting unit and a current control signal to the converting circuit, capable of controlling the amplitude of the current flowing through the light emitting diode. ## Claims ### Claim 1 A lighting apparatus, comprising: a lighting unit comprising at least one light emitting diode and a switching device connected with each other in series; a converting circuit having an output end electrically connected to the lighting unit for driving the lighting unit; a sensing circuit comprising a sensing element, capable of indirectly detecting the current flowing through the light emitting diode and outputting a feedback signal; and a current control circuit receiving a reference current, the feedback signal and a dimming command and capable of sending a dimming control signal to the lighting unit and a current control signal to the converting circuit for controlling the amplitude of the current flowing through the light emitting diode. ### Claim 2 (depends on 1) The lighting apparatus according to claim 1, wherein the reference current is generated inside the lighting apparatus or is inputted from an external device and the converting circuit is a fly-back converter, a buck converter, a boost converter, a buck-boost converter, a forward converter, a half-bridge converter, or a full-bridge converter. ### Claim 3 (depends on 1) The lighting apparatus according to claim 1, wherein the current control circuit comprises: a pulse width modulation (PWM) signal generator receiving an external dimming signal and capable of outputting the dimming control signal to the lighting unit; a signal converter receiving the reference current and transforming the reference current to an average reference current according to the dimming control signal; and a regulator generating a current control signal according to the average reference current and the feedback signal and capable of transmitting the current control signal to the converting circuit. ### Claim 4 (depends on 3) The lighting apparatus according to claim 3, wherein the current control circuit further comprises: a comparing circuit electrically connected to the regulator, and comparing the average reference current with the feedback signal so as to output a current difference. ### Claim 5 (depends on 1) The lighting apparatus according to claim 1, further comprising: a capacitor connected to the lighting unit in parallel, wherein the sensing circuit further comprises a sensing signal converter. ### Claim 6 (depends on 5) The lighting apparatus according to claim 5, wherein the sensing element of the sensing circuit connects to the lighting unit and the capacitor, which are connected in parallel, in series, one end of the sensing element connecting to the lighting unit and the capacitor is electrically connected to the sensing signal converter, and the other end of the sensing element is electrically connected to the output end of the converting circuit. ### Claim 7 (depends on 5) The lighting apparatus according to claim 5, wherein the sensing element is a resistor or a current transformer ### Claim 8 (depends on 6) The lighting apparatus according to claim 6, wherein the other end of the sensing element is electrically connected to the output end of the converting circuit and is grounded, and the sensing signal converter is a filter. ### Claim 9 (depends on 6) The lighting apparatus according to claim 6, wherein the converting circuit is a fly-back converter, a buck converter, a boost converter, a buck-boost converter, a forward converter, a half-bridge converter, or a full-bridge converter. ### Claim 10 (depends on 9) The lighting apparatus according to claim 9, wherein the current control circuit is a digital controller. ### Claim 11 (depends on 5) The lighting apparatus according to claim 5, wherein the converting circuit is a fly-back converter comprising: a buffer circuit; a transformer having a primary side connected to the buffer circuit in parallel; a switch connecting to the buffer circuit and the primary side of the transformer, which are connected in parallel, in series, and is turned on or turned off according to the current control signal from the current control circuit; and a diode connecting to a secondary side of the transformer; wherein the sensing element of the sensing circuit is connected to the switch in series, one end of the sensing element connected to the switch is further electrically connected to the sensing signal converter, and the other end of the sensing element is electrically connected to an input end of the converting circuit. ### Claim 12 (depends on 11) The lighting apparatus according to claim 11, wherein the sensing element is a resistor or a current transformer ### Claim 13 (depends on 11) The lighting apparatus according to claim 11, wherein the other end of the sensing element is electrically connected to the input end of the converting circuit and is grounded, and the sensing signal converter is a calculator. ### Claim 14 (depends on 5) The lighting apparatus according to claim 5, wherein the converting circuit is buck converter comprising: a switch; a diode having a cathode, which is electrically connected to one end of the switch, and an anode, which is grounded; and an inductance having one end electrically connected to one end of the switch and the cathode of the diode, wherein the other end of the inductance and the anode of the diode form an output end of the buck converter; wherein the other end of the switch and the anode of the diode form an input end of the buck converter, and the switch is turned on or turned off according to the current control signal outputted from the current control circuit. ### Claim 15 (depends on 14) The lighting apparatus according to claim 14, wherein the sensing element and the diode of the buck converter are connected in series, one end of the sensing element, which is connected to the diode, is further electrically connected to the sensing signal converter, and the other end of the sensing element is electrically connected to the input end of the buck converter, the lighting unit and the capacitor, which are connected in parallel. ### Claim 16 (depends on 15) The lighting apparatus according to claim 15, wherein the sensing element is a resistor or a current transformer ### Claim 17 (depends on 15) The lighting apparatus according to claim 15, wherein the other end of the sensing element is electrically connected to the input end of the buck converter, the lighting unit and the capacitor, which are connected in parallel, and grounded, and the sensing signal converter is a calculator. ### Claim 18 (depends on 14) The lighting apparatus according to claim 14, wherein one end of the sensing element is electrically connected to the anode of the diode of the buck converter, the lighting unit and the capacitor, which are connected in parallel, and grounded, the other end of the sensing element is electrically connected to the input end of the buck converter and the sensing signal converter, and the sensing signal converter is a calculator. ### Claim 19 (depends on 14) The lighting apparatus according to claim 14, wherein the sensing element is inductively coupled with the inductance of the buck converter, and the sensing signal converter is a calculator. ### Claim 20 A control method of a lighting apparatus, wherein the lighting apparatus comprises a lighting unit, a converting circuit, a current control circuit and a sensing circuit, and the lighting unit comprises at least one light emitting diode, the control method comprising steps of: indirectly detecting a current flowing through the light emitting diode by the sensing circuit so as to generate a feedback signal; receiving a dimming command to generate a dimming control signal to control the current of the light emitting diode; and receiving a reference current to generate a current control signal according to the dimming control signal, the reference current and the feedback signal, thereby controlling the amplitude of the current flowing through the light emitting diode, wherein the reference current is from the internal of the lighting apparatus or an external apparatus. ### Claim 21 (depends on 20) The control method according to claim 20, further comprising steps of: transforming the reference current to an average reference current according to the dimming control signal; comparing the feedback signal and the average reference current to obtain a difference value; and generating the current control signal according to the difference value to control the amplitude of the current flowing through the light emitting diode.