LED lamp, illumination device including the LED lamp and current control method of the LED lamp

• US 8,779,679 B2
• Filed: 10/25/2012
• Issued: 07/15/2014
• Est. Priority Date: 10/25/2012
• Status: Active Grant

• Current Assignee: Systems LMP Incorporated
• Original Assignee: M-System Co., Ltd.
• Inventors: Miyamichi, Saburo
• Primary Examiner(s): LE, DON P
• Application Number:
  US14/110,541
• Publication Number:
  US 20140117853A1
• Time in Patent Office: 628 Days
• Field of Search: 315/192, 315/205, 315/207, 315/254, 315/276, 315/259, 315/307
• US Class Current: 315/259
• CPC Class Codes: H05B 45/3578 Emulating the electrical or functional characteristics of discharge lamps
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: H05B 45/59 for reducing or suppressing flicker or glow effects
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

An LED lamp 20 according to one embodiment of the present invention includes a pair of input terminal parts 20a, 20c, a rectifier circuit unit 22, and an LED unit 24. And the LED lamp 20 has variable inductance units L50, L60 for causing an AC to flow from one of the pair of input terminal parts 20a, 20c to the other input terminal part through the rectifier circuit unit 22, a current detection unit 31 for detecting a magnitude of a DC flowing through the LED unit 24, and an inductance variable control unit 32 for making inductance values of the variable inductance units L50, L60 variable according to the magnitude of the DC detected by the current detection unit 31.

Claims

1. An LED lamp including a pair of input terminal parts;

a rectifier circuit unit rectifying an AC, inputted from the outside to the pair of input terminal parts, to a DC; and

an LED unit emitting light by electrification of the DC outputted from the rectifier circuit unit;

the LED lamp having;

a variable inductance unit, in a circuit between the pair of input terminal parts and the rectifier circuit unit, for causing the AC to flow from one of the pair of input terminal parts to the other input terminal part through the rectifier circuit unit;

a current detection unit, in a circuit between the rectifier circuit unit and the LED unit, for detecting a magnitude of the DC flowing through the LED unit;

an inductance variable control unit for making an inductance value of the variable inductance unit variable according to the magnitude of the DC detected by the current detection unit; and

a PWM control unit, in a circuit between the rectifier circuit unit and the LED unit, capable of PWM control of a current flowing through the LED unit according to a duty ratio;

wherein the PWM control unit is switchable between a case where the PWM control of the current flowing through the LED unit is performed, and a case where PWM control of the current flowing through the LED unit is not performed, according to a frequency of the external AC inputted to the pair of input terminal parts; and

wherein, in the case where the PWM control unit does not perform PWM control, the current detection unit detects the magnitude of the DC flowing through the LED unit, and the inductance variable control unit makes the inductance value of the variable inductance unit variable according to the magnitude of the DC.

2. An LED lamp according to claim 1, further including a threshold element, in a circuit between the pair of input terminal parts and the rectifier circuit unit, for causing the AC to flow from one of the pair of input terminal parts to the other input terminal part through the rectifier circuit unit;

wherein the threshold element is adapted to short-circuit both ends thereof after a lapse of a predetermined time from when the AC exceeding a predetermined threshold is inputted to the pair of input terminal parts from the outside; and

wherein the inductance variable control unit makes the inductance value of the variable inductance unit variable according to the magnitude of the DC detected after the both ends of the threshold element are short-circuited.

3. An LED lamp according to claim 1, further including a circuit interrupt unit, in a circuit between the pair of input terminal parts and the rectifier circuit unit, capable of interrupting the AC flowing from one of the pair of input terminal parts to the other input terminal part through the rectifier circuit unit;

wherein the circuit interrupt unit interrupts the AC when the magnitude of the DC detected by the current detection unit is higher than a predetermined upper limit or lower than a predetermined lower limit.

4. An illumination device including the LED lamp according to claim 1.

5. A current control method of an LED lamp including a pair of input terminal parts;

a rectifier circuit unit rectifying an AC, inputted from the outside to the pair of input terminal parts, to a DC; and

an LED unit emitting light by electrification of the DC outputted from the rectifier circuit unit, the method including the steps of;

causing the AC, in a circuit between the pair of input terminal parts and the rectifier circuit unit, to flow from one of the pair of input terminal parts to the other input terminal part by way of the rectifier circuit unit through a variable inductance unit;

switching between a case where the PWM control of the current flowing through the LED unit is performed, and a case where PWM control of the current flowing through the LED unit is not performed, according to a frequency of the external AC inputted to the pair of input terminal parts, wherein the switching is performed by a PWM control unit, in a circuit between the rectifier circuit unit and the LED unit, capable of PWM control of a current flowing through the LED unit according to a duty ratio;

detecting, in the case where the PWM control unit does not perform PWM control, a magnitude of the DC flowing through the LED unit in a circuit between the rectifier circuit unit and the LED unit; and

making an inductance value of the variable inductance unit variable according to the detected magnitude of the DC in the case where the PWM control unit does not perform PWM control;

wherein the magnitude of the DC flowing through the LED unit is controlled so as to fall within a predetermined range.