Electrode-less discharge lamp lighting apparatus, bulb-shaped electrode-less fluorescent lamp, and discharge lamp lighting apparatus

• US 6,870,327 B2
• Filed: 11/17/2003
• Issued: 03/22/2005
• Est. Priority Date: 09/12/2002
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Takeda, Mamoru, Nagagata, Nobuyoshi, Takahashi, Kenichirou, Kominami, Satoshi, Kurachi, Toshiaki, Miyazaki, Kouji
• Primary Examiner(s): TRAN, THUY V
• Application Number:
  US10/713,115
• Publication Number:
  US 20040100205A1
• Time in Patent Office: 491 Days
• Field of Search: 315/200.R, 315/209.R, 315224-226, 315/244, 315/248, 315/291, 315/299, 315/301, 315/307, 315/360, 315/DIG.4, 315/DIG.7
• US Class Current: 315/248
• CPC Class Codes: H05B 41/2806 with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
• CPC Class Codes: H05B 41/2828 using control circuits for the switching elements H05B41/2827 takes precedence
• CPC Class Codes: H05B 41/3924 by phase control, e.g. using a triac H05B41/3922 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 315/04 Dimming circuit for fluorescent lamps

Abstract

An electrode-less discharge lamp lighting apparatus which is electrically connected to a dimming unit (2) is provided with: an electrode-less fluorescent lamp (3); and a lighting circuit (4) operable to apply a high-frequency voltage to the electrode-less fluorescent lamp (3), wherein the lighting circuit (4) includes: an AC/DC converting unit (5) operable to convert a phase-controlled AC voltage outputted from the dimming unit (2) into a DC voltage; a DC/AC converting unit (6) operable to convert the DC voltage into a high-frequency voltage; and a dimming controlling unit (7) that includes a resistor (29), a switching element (28), and a timer circuit (27) so as to detect a timing of a turn-on of the phase-controlled AC voltage and to, based on the detected timing, allow a current whose value is at least a threshold to flow across output terminals of the AC/DC converting unit (5) for at least a duration of a time lag between the turn-on of the phase-controlled AC voltage and the generation of the high-frequency voltage by the DC/AC converting unit (6).

Claims

1. An electrode-less discharge lamp lighting apparatus which is electrically connected to a dimming unit, comprising:

an electrode-less discharge lamp; and

a lighting circuit operable to apply a high-frequency voltage to the electrode-less discharge lamp,

wherein the lighting circuit includes;

an AC/DC converting unit operable to convert a phase-controlled AC voltage outputted from the dimming unit into a DC voltage;

a DC/AC converting unit operable to convert the DC voltage into a high-frequency voltage and operable to intermittently drive the electrode-less discharge lamp by applying the high-frequency voltage to the electrode-less discharge lamp during a lighting-up period of the electrode-less discharge lamp so that the electrode-less discharge lamp illuminates and by halting a generation of the high-frequency voltage during a lighting-out period of the electrode-less discharge lamp so that the electrode-less discharge lamp is extinguished; and

a dimming controlling unit operable to detect a timing of a turn-on of the phase-controlled AC voltage, wherein, based on the detected timing, the dimming controlling unit outputs an intermittent command signal to vary a ratio between the lighting-up and lighting-out periods and allows a current whose value is at least a threshold to flow across output terminals of the AC/DC converting unit for at least a duration of a time lag between the turn-on of the phase-controlled AC voltage and the generation of the high-frequency voltage by the DC/AC converting unit.

2. The electrode-less discharge lamp lighting apparatus according to claim 1,

wherein the dimming unit includes a switching element operable to pass a current in both directions, and

the threshold is a value of a minimum current required for the switching element to keep a turn-on state.

3. The electrode-less discharge lamp lighting apparatus according to claim 2,

wherein the switching element is a triac, and

the threshold is a value of a holding current of the triac.

4. The electrode-less discharge lamp lighting apparatus according to claim 1,

wherein the dimming controlling unit includes:

a timer circuit operable to output a signal indicating a period of time that lasts at least the time lag; and

a switching element operable to allow a current whose value is at least the threshold to flow across the output terminals of the AC/DC converting unit via a resistor for the period of time indicated by the signal inputted by the timer circuit.

5. The electrode-less discharge lamp lighting apparatus according to claim 4,

wherein the dimming controlling unit further includes:

a dimming control signal inputting circuit operable to output a signal indicating the turn-on of the phase-controlled AC voltage; and

a signal transmitting circuit operable to transmit the signal outputted from the dimming control signal inputting circuit to the timer circuit in a state where the signal transmitting circuit is electrically isolated.

6. The electrode-less discharge lamp lighting apparatus according to claim 5,

wherein the timer circuit includes:

a capacitor;

a differentiating circuit operable to differentiate the signal transmitted by the signal transmitting circuit;

a switching element operable to allow the capacitor one of to be charged and to discharge in accordance with an output from the differentiating circuit; and

a comparator operable to compare an electric potential of the capacitor to a predetermined electric potential and output a signal as a comparison result that indicates the period of time that lasts at least the time lag.

7. The electrode-less discharge lamp lighting apparatus according to claim 1,

wherein the dimming controlling unit, when a dimming state set by the intermittent command signal is one of a full-state and a dimmed state, allows the current whose value is at least the threshold to flow across the output terminals of the AC/DC converting unit for at least the duration of the time lag between the turn-on of the phase-controlled AC voltage and the generation of the high-frequency voltage by the DC/AC converting unit.

8. The electrode-less discharge lamp lighting apparatus according to claim 1,

wherein the dimming controlling unit further includes:

a sawtoothed wave signal generating circuit operable to generate one of a sawtoothed wave signal and a triangular wave signal that is synchronized with the timing of the turn-on of the phase-controlled AC voltage;

a dimming command signal generating circuit operable to generate a dimming command signal that carries a voltage corresponding to a period of time during which the phase-controlled AC voltage is turned on; and

a comparator operable to compare one of the sawtoothed wave signal and the triangular wave signal to the dimming command signal and output the intermittent command signal as a comparison result.

9. The electrode-less discharge lamp lighting apparatus according to claim 8,

wherein the dimming controlling unit further includes:

a dimming control signal inputting circuit operable to output a signal indicating the turn-on of the phase-controlled AC voltage; and

a signal transmitting circuit operable to transmit the signal outputted from the dimming control signal inputting circuit to the sawtoothed wave signal generating circuit in a state where the signal transmitting circuit is electrically isolated.

10. The electrode-less discharge lamp lighting apparatus according to claim 9,

wherein the sawtoothed wave signal generating circuit includes:

a capacitor;

a differentiating circuit operable to differentiate the signal transmitted by the signal transmitting circuit;

a switching element operable to allow the capacitor one of to be charged and to discharge in accordance with an output from the differentiating circuit; and

an outputting circuit operable to output an electric potential of the capacitor as one of the sawtoothed wave signal and the triangular wave signal.

11. A bulb-shaped electrode-less fluorescent lamp which is electrically connected to a dimming unit, comprising:

an electrode-less fluorescent lamp;

a lighting circuit operable to apply a high-frequency voltage to the electrode-less fluorescent lamp; and

a base operable to electrically connect the dimming unit to the lighting circuit,

wherein the electrode-less fluorescent lamp, the lighting circuit, and the base are formed in one piece in a shape of a bulb, and

wherein the lighting circuit includes;

an AC/DC converting unit operable to convert a phase-controlled AC voltage outputted from the dimming unit via the base into a DC voltage;

a DC/AC converting unit operable to convert the DC voltage into a high-frequency voltage and operable to intermittently drive the electrode-less discharge lamp by applying the high-frequency voltage to the electrode-less fluorescent lamp during a lighting-up period of the electrode-less fluorescent lamp so that the electrode-less fluorescent lamp illuminates and by halting a generation of the high-frequency voltage during a lighting-out period of the electrode-less fluorescent lamp so that the electrode-less fluorescent lamp is extinguished; and

a dimming controlling unit operable to detect a timing of a turn-on of the phase-controlled AC voltage, wherein, based on the detected timing, the dimming controlling unit outputs an intermittent command signal to vary a ratio between the lighting-up and lighting-out periods and allows a current whose value is at least a threshold to flow across output terminals of the AC/DC converting unit for at least a duration of a time lag between the turn-on of the phase-controlled AC voltage and the generation of the high-frequency voltage by the DC/AC converting unit.

12. The bulb-shaped electrode-less fluorescent lamp according to claim 11,

wherein the electrode-less fluorescent lamp has a concave part, and

an induction coil to which the high-frequency voltage is applied is inserted into the concave part.

13. The bulb-shaped electrode-less fluorescent lamp according to claim 12,

wherein the dimming unit includes a switching element operable to pass a current in both directions, and

the threshold is a value of a minimum current required for the switching element to keep a turn-on state.

14. The bulb-shaped electrode-less fluorescent lamp according to claim 13,

wherein the switching element included in the dimming unit is a triac, and

the threshold is a value of a holding current of the triac.

15. A discharge lamp lighting apparatus which is electrically connected to a dimming unit, comprising:

a discharge lamp; and

a lighting circuit operable to apply a high-frequency voltage to the discharge lamp,

wherein the lighting circuit includes;

an AC/DC converting unit operable to convert a phase-controlled AC voltage outputted from the dimming unit into a DC voltage;

a DC/AC converting unit operable to convert the DC voltage into a high-frequency voltage and operable to intermittently drive the discharge lamp by applying the high-frequency voltage to the discharge lamp during a lighting-up period of the discharge lamp so that the discharge lamp illuminates and by halting a generation of the high-frequency voltage during a lighting-out period of the discharge lamp so that the discharge lamp is extinguished; and

a dimming controlling unit operable to detect a timing of a turn-on of the phase-controlled AC voltage, wherein, based on the detected timing, the dimming controlling unit outputs an intermittent command signal to vary a ratio between the lighting-up and lighting-out periods and allows a current whose value is at least a threshold to flow across output terminals of the AC/DC converting unit for at least a duration of a time lag between the turn-on of the phase-controlled AC voltage and the generation of the high-frequency voltage by the DC/AC converting unit.