# US 11,910,501 B2 · Method and apparatus for providing a passive color control scheme using blue and red emitters

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- Number: US 11,910,501 B2
- Document ID: US11910501B2
- Status: Granted
- Kind: B2
- Application number: 17/141,457
- Filed: 2021-01-05
- Published: 2021-04-29
- Granted: 2024-02-20
- Earliest claimed: 2012-12-07
- Assignees: Signify Holding B.V.
- Applicants: Signify Holding B.V.
- Inventors: Tao Tong
- Web page: https://patentgrep.com/patent/US11910501B2

## CPC

- H05B 45/28: using temperature feedback
- F21K 9/64: using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
- H05B 45/10: Controlling the intensity of the light
- H05B 45/20: Controlling the colour of the light
- H10H 20/851: Wavelength conversion means
- H10W 90/00: Package configurations
- H10H 20/857: Interconnections, e.g. lead-frames, bond wires or solder balls
- 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
- F21K: NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A lighting device capable of generating warm or neutral white light using blue light-emitting diodes (“LEDs”), red LEDs, and/or luminescent material that responds to blue LED emission is disclosed. The lighting device includes multiple first solid-state light-emitting structures (“SLSs”), second SLSs, and balancing resistor element. The first SLS such as a string of blue LED dies connected in series is able to convert electrical energy to blue optical light, which is partially turned into longer wavelength emission by the luminescent material. The second SLS such as a red LED die is configured to convert electrical energy to red optical light, wherein the second SLSs are connected in series. While the first SLSs and second SLSs are coupled in parallel, the balancing resistor element provides load balance for current redistribution between the first and second SLSs in response to fluctuation of operating temperature.

## Claims

### Claim 1

A solid-state lighting device comprising:
a first string of light-emitting diodes (“LEDs”) having a first end and a second end, the first string being a plurality of LEDs arranged in series and having multiple junctions configured to convert electrical energy to a bluish optical light;
a second string of LEDs having a first end and a second end, the second string being a plurality of LEDs arranged in series and having multiple junctions configured to convert electrical energy to a reddish optical light, wherein a first end of the second string of LEDs is electrically coupled to the first end of the first string of LEDs in a parallel configuration; and
a red light flux balancing resistor element having a first end and a second end, the first end of the red light flux balancing resistor element being electrically coupled in series to the second end of the second string of LEDs, the second end of the red light flux balancing resistor being electrically coupled to the second end of the first string of LEDs, the second string of LEDs and red light flux balancing resistor series being arranged in parallel with the first string of LEDs and configured to increase current through the second string of LEDs and decrease current through the first string of LEDs in response to an increase of a junction temperature of the second string of LEDs, wherein the red light balancing resistor element includes a passive resistor element having a predefined value based on one or more physical properties of at least one of the first and second strings of LEDs to generate a predefined desirable color point, wherein the first end of the red flux balancing resistor is electrically coupled to a negative terminal of an LED of the first string of LEDs.

### Claim 2 (depends on 1)

The solid-state lighting device of claim 1, wherein the fluctuation of a junction temperature of the second string of LEDs is due to a temperature dependent characteristic of the second string of LEDs.

### Claim 3 (depends on 1)

The device of claim 1, wherein the string of first LEDs is configured to convert electrical energy to blue light having a range of wavelengths from 400 nm to 500 nm.

### Claim 4 (depends on 1)

The device of claim 1, wherein the string of second LEDs is configured to convert electrical energy to red light having a range of wavelengths between 580 nm and 700 nm.

### Claim 5 (depends on 1)

The device of claim 1, further comprising a bluish light flux balancing resistor element having a first end and a second end, the first end of the bluish light flux balancing resistor element being electrically coupled in series to the second end of the first string of LEDs, the second end of the blueish light flux balancing resistor being electrically coupled to the second end of the red light flux balancing resistor, the second string of LEDs and red light flux balancing resistor series being arranged in parallel with the first string of LEDs and the blueish light flux balancing resistor series and configured to redistribute current in response to a fluctuation of a junction temperature of the first string of LEDs, wherein the blueish light balancing resistor element includes a passive resistor element having a predefined value based on one or more physical properties of at least one of the first and second strings of LEDs to generate the predefined desirable color point.

### Claim 6 (depends on 1)

The device of claim 1, wherein the device generates the predefined desirable color point by adjusting the current through the first string of LEDs and the second string of LEDs.

### Claim 7

A method of generating a predefined desirable color point using a solid-state lighting device comprising:
arranging in a series configuration a first string of light-emitting diodes (“LEDs”), having a first end and a second end and having multiple junctions configured to convert electrical energy to a bluish optical light;
arranging in a series configuration a second string of LEDs having a first end and a second end and having multiple junctions configured to convert electrical energy to a reddish optical light,
arranging in a parallel configuration the first end of the second string of LEDs to be electrically coupled to the first end of the first string of LEDs; and
arranging in series with the second end of the second string of LEDs a red light flux balancing resistor element having a first end and a second end, wherein the first end of the red light flux balancing resistor element is electrically coupled to the second end of the second string of LEDs, and wherein the first end of the red flux balancing resistor is electrically coupled to a negative terminal of an LED of the first string of LEDs;
arranging in parallel with the second end of the first string of LEDs the second end of the red light flux balancing resistor, wherein the second string of LEDs and red light flux balancing resistor series are arranged in parallel with the first string of LEDs;
increasing a current through the second string of LEDs and decreasing a current through the first string of LEDs in response to an increase of a junction temperature of the second string of LEDs; and
generating the predefined desirable color point using the red light flux balancing resistor element, wherein the red light balancing resistor element includes a passive resistor element having a predefined value based on one or more physical properties of at least one of the first and second strings of LEDs.

### Claim 8 (depends on 7)

The method of claim 7, wherein the fluctuation of a junction temperature of the second string of LEDs is due to a temperature dependent characteristic of the second string of LEDs.

### Claim 9 (depends on 7)

The method of claim 7, wherein the string of first LEDs is configured to convert electrical energy to blue light having a range of wavelengths from 400 nm to 500 nm.

### Claim 10 (depends on 7)

The method of claim 7, wherein the string of second LEDs is configured to convert electrical energy to red light having a range of wavelengths between 580 nm and 700 nm.

### Claim 11 (depends on 7)

The method of claim 7, further comprising:
arranging in series a bluish light flux balancing resistor element having a first end and a second end to the second end of the first string of LEDs;
arranging in parallel the second end of the blueish light flux balancing resistor and the second end of the red light flux balancing resistor, wherein the second string of LEDs and red light flux balancing resistor series being arranged in parallel with the first string of LEDs and the blueish light flux balancing resistor series; and
redistributing the current in response to a fluctuation of a junction temperature of the first string of LEDs; and
generating the predefined desirable color point using the blueish light balancing resistor element, wherein the blueish light balancing element includes a passive resistor element having a predefined value based on one or more physical properties of at least one of the first and second strings of LEDs.

### Claim 12 (depends on 7)

The method of claim 7, wherein generating the predefined desirable color point further comprises adjusting the current through the first string of LEDs and the second string of LEDs.