LED lighting device and driving method for the same

• US 8,410,727 B2
• Filed: 03/07/2008
• Issued: 04/02/2013
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: IRIS Ohyama Incorporated (Oyama KK)
• Original Assignee: ROHM Co., Ltd.
• Inventors: Mizuno, Jun
• Primary Examiner(s): Tran, Thuy Vinh
• Assistant Examiner(s): Arpin, Anthony
• Application Number:
  US12/530,458
• Publication Number:
  US 20100148703A1
• Time in Patent Office: 1,852 Days
• Field of Search: 315/209.R, 315/291, 315/312, 315/313, 315/360
• US Class Current: 315/313
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• 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

It is provided an LED lighting device calibratable to 0 to 100% of wide range about a chromaticity and luminance of a illumination light by a simple configuration, and a driving method for the LED lighting device. The LED lighting device is provided with a first light-emitting unit and a second light-emitting unit differing a color temperature mutually, and a control circuit for executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit, and for executing a light control of the first light-emitting unit and the second light-emitting unit by a PNM (Pulse Number Modulation) control in a fixed cycle so as to have a lighting period Ton for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period Toff for quenching both the first light-emitting unit and the second light-emitting unit.

Claims

1. An LED lighting device comprising:

a first light-emitting unit and a second light-emitting unit differing in a color temperature mutually; and

a control circuit for generating a switching control signal based on a chromaticity control signal and a luminance control signal, and executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit so as to have a lighting period for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period for quenching both the first light-emitting unit and the second light-emitting unit, according to the generated switching control signal, and for generating a pulse number modulation output signal based on the chromaticity control signal and the luminance control signal, and executing a light control of the first light-emitting unit and the second light-emitting unit by a pulse number modulation control in a fixed cycle according to the switching control signal on which the generated pulse number modulation output signal is superimposed.

2. The LED lighting device according to claim 1, wherein

the control circuit executes a variable control of a ratio between the lighting period of the first light-emitting unit and the lighting period of the second light-emitting unit in the lighting period, according to the chromaticity control signal, and executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle.

3. The LED lighting device according to claim 1, wherein

the control circuit executes a variable control of the length of the quenching period according to the luminance control signal, whereas the length of the lighting period is kept up uniformly, and executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle.

4. The LED lighting device according to claim 1, wherein

the control circuit executes a variable control of the ratio between the lighting period and the quenching period in a predetermined lighting/quenching cycle according to the luminance control signal, and executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle.

5. The LED lighting device according to claim 1, wherein

the first light-emitting unit and the second light-emitting unit includes a blue light-emitting diode for emitting a blue light, and a fluorescence layer having a transparent resin which mixes uniformly a red phosphor and a green phosphor for emitting a red light and a green light respectively by exciting by the blue light, or a yellow phosphor for emitting the yellow light by exciting by the blue light.

6. The LED lighting device according to claim 1, wherein

the color temperature of the first light-emitting unit is included in the range of 2500K to 3000K, and the color temperature of the second light-emitting unit is included in the range of 3000K to 6500K.

7. An LED lighting device comprising:

a first light-emitting unit and a second light-emitting unit differing in a color temperature mutually; and

a control circuit for executing a light/quench control of the first light-emitting unit and the second light-emitting unit, the control circuit including a light/quench control unit for generating a switching control signal based on a chromaticity control signal and a luminance control signal, and executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit so as to have a lighting period for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period for quenching both the first light-emitting unit and the second light-emitting unit, according to the generated switching control signal, and a pulse number modulation control unit for generating a pulse number modulation output signal based on the chromaticity control signal and the luminance control signal, and executing a light control of the first light-emitting unit and the second light-emitting unit by a pulse number modulation control in a fixed cycle according to the switching control signal on which the generated pulse number modulation output signal is superimposed.

8. The LED lighting device according to claim 7, wherein

the light/quench control unit further executes a variable control of the ratio between the lighting period of the first light-emitting unit and the lighting period of the second light-emitting unit in the lighting period according to the chromaticity control signal, and the pulse number modulation control unit also further executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the chromaticity control signal.

9. THe LED lighting device according to claim 7, wherein

the light/quench control unit further executes a variable control of the length of the quenching period according to the luminance control signal whereas the length of the lighting period is kept up uniformly, and the pulse number modulation control unit also further executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the luminance control signal.

10. The LED lighting device accordning to claim 7, wherein

the light/quench control unit further executes a variable control of the ratio between the lighting period and the quenching period in a predetermined lighting/quenching cycle according to the luminance control signal, and the pulse number modulation control unit is also further executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the luminance control signal.

11. An LED lighting device comprising:

a first light-emitting unit and a second light-emitting unit differing in a color temperature mutually; and

a changing operation unit for executing an operation for changing a color temperature of illumination light;

a control circuit for executing a cyclic light/quench control of the first light/emitting unit and the second light-emitting unit so as to have a lighting period for lighting/quenching the first light-emitting unit and the second light-emitting unit and the second light-emitting unit, and for determining a length of the lighting period of the first light-emitting unit and a length of the lighting period of the second light-emitting unit in the lighting period in response to the operation in the changing operation unit so that an amount of variation of an inverse correlated color temperature of the illumination light with respect to an amount of the operation of the changing operation unit becomes linear.

12. The LED lighting device according to claim 11, wherein

the control circuit executes a variable control of the length of the quenching period according to a luminance control signal whereas the length of the lighting period is kept up uniformly.

13. The LED lighting device according to claim 11, wherein

the control circuit determines the length of the lighting period and the length of the quenching period in a predetermined lighting/quenching cycle according to a luminance control signal.

14. An LED lighting device comprising:

a first light-emitting unit and a second light-emitting unit differing in a color temperature mutually; and

a changing operation unit for executing an operation for changing a color temperature of illumination light;

a control circuit for executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit so as to have a lighting period for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period quenching both the first light-emitting unit and the second light-emitting unit, and for determining a length of the lighting period of the first light-emitting unit and a length of the lighting period of the second light-emitting unit in the lighting period, and executing a light control of the first light-emitting unit and the second light-emitting unit by a pulse number modulation control in a fixed cycle, in response to the operation in the changing operation unit so that an amount of variation of an inverse correlated color temperature of the illumination light with respect to an amount of the operation of the changing operation unit becomes linear.

15. The LED lighting device according to claim 14, wherein

the control circuit executes a variable control of the length of the quenching period according to a luminance control signal whereas the length of the lighting period is kept up uniformly.

16. The LED lighting device according to claim 14, wherein

the control circuit determines the length of the lighting period and the length of the quenching period in a predetermined lighting/quenching cycle according to a luminance control signal.

17. An LED lighting device comprising:

a first light-emitting unit and a second light-emitting unit differing in a color temperature mutually; and

a changing operation unit for executing an operation for changing a color temperature of illumination light;

a control circuit for executing a light/quench control of the first light-emitting unit and the second light-emitting unit, the control circuit including a light/quench control unit for executing a cyclic light/quench control of the first light-emitting unit and the second light-emitting unit, and further determining a length of the lighting period of the first light-emitting unit and a length of the lighting period of the second light-emitting unit in the lighting period in response to the operation in the changing operation unit so that an amount of variation of an inverse correlated color temperature of the illumination light with respect to an amount of the operation of the changing operation unit becomes linear so as to have a lighting period for lighting/quenching the first light-emitting unit and the second light-emitting unit complementarily, and a quenching period for quenching both the first light-emitting unit and the second light-emitting unit, and a pulse number modulation control unit for executing a light control of the first light-emitting unit and the second light-emitting unit by a pulse number modulation control in a fixed cycle, and further executing a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the amount of variation of the inverse correlated color temperature.

18. The LED lighting device according to claim 17, wherein

the light/quench control unit further executes a variable control of the length of the quenching period according to a luminance control signal whereas the length of the lighting period is kept up uniformly, and the pulse number modulation control unit also further executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the luminance control signal.

19. The LED lighting device according to claim 17, wherein

the light/quench control unit further determines the length of the lighting period and the length of the quenching period in a predetermined lighting/quenching cycle according to a luminance control signal, and the pulse number modulation control unit is also further executes a light control of the first light-emitting unit and the second light-emitting unit by the pulse number modulation control in the fixed cycle according to the luminance control signal.

20. A driving method of an LED lighting device, the LED lighting device including a first light emitting diode and a second light emitting diode differing in a color temperature mutually, a microcomputer for executing a light/quench control of the first light emitting diode and the second light emitting diode, and a changing operation unit for executing an operation for changing a color temperature of illumination light, the driving method comprising:

executing, by the microcomputer, a cyclic light/quench control of the first light emitting diode and the second light emitting diode so as to have a lighting period for lighting/quenching the first light emitting diode and the second light emitting diode complementarily, and a quenching period for quenching both the first light emitting diode and the second light emitting diode; and

determining, by the microcomputer, a length of the lighting period of the first light emitting diode and a length of the lighting period of the second light emitting diode in the lighting period in response to the operation in the changing operation unit so that an amount of variation of an inverse correlated color temperature of the illumination light with respect to an amount of the operation of the changing operation unit becomes linear.