Bonding an optical element to a light emitting device
A device is provided with at least one light emitting device (LED) die mounted on a submount with an optical element subsequently thermally bonded to the LED die. The LED die is electrically coupled to the submount through contact bumps that have a higher temperature melting point than is used to thermally bond the optical element to the LED die. In one implementation, a single optical element is bonded to a plurality of LED dice that are mounted to the submount and the submount and the optical element have approximately the same coefficients of thermal expansion. Alternatively, a number of optical elements may be used. The optical element or LED die may be covered with a coating of wavelength converting material. In one implementation, the device is tested to determine the wavelengths produced and additional layers of the wavelength converting material are added until the desired wavelengths are produced.
1. A method comprising:
providing at least one phosphor converted light emitting device that produces light with a broad spectrum;
providing a plurality of color light emitting devices, each of which produces light with a narrow spectrum;
mixing the light produced by the at least one phosphor converted light emitting device and the plurality of color light emitting devices to produce light with a resulting spectrum that is more continuous than the broad spectrum produced by the at least one phosphor converted light emitting devices;
controlling the brightness of the light produced by the plurality of color light emitting devices to vary the correlated color temperature of the resulting spectrum.
2. The method of claim 1 , further comprising mounting the at least one phosphor converted light emitting device and the plurality of color light emitting devices on a board.
3. The method of claim 1 , wherein a greater number of phosphor converted light emitting devices are provided than color light emitting devices.
4. The method of claim 3 , wherein over twice as many phosphor converted light emitting devices as color light emitting devices are provided.
5. The method of claim 1 , wherein the color light emitting devices produce blue, cyan, amber and red light.
6. The method of claim 1 , wherein the brightness of the light produced by each color light emitting device is controlled separately to vary the correlated color temperature.
7. The method of claim 1 , wherein the brightness of each different colored light produced by the color light emitting devices is controlled separately to vary the correlated color temperature.
8. A device comprising:
an array of light emitting diodes (LEDs) mounted on a board, the array comprising at least one phosphor converted LED that produces light with a broad spectrum and a plurality of color LEDs, each of which produces light with a narrow spectrum;
a transparent element disposed over the array of LEDs, wherein the transparent element mixes the light produced by the at least one phosphor converted light emitting device with the light produced by the plurality of color light emitting devices to produce light with a resulting spectrum that is more continuous than the broad spectrum produced by the at least one phosphor converted light emitting devices; and
a controller electrically connected to the array of LEDs for controlling the brightness of the light produced by the plurality of color light emitting devices to vary the correlated color temperature of the resulting spectrum.
9. The device of claim 8 , wherein a plurality of phosphor converted LEDs are mounted on the board, and a greater number of phosphor converted LEDs than color LEDs are mounted on the board.
10. The device of claim 9 , wherein over twice as many phosphor converted LEDs as color LEDs are mounted on the board.
11. The device of claim 8 , wherein the color LEDs produce blue, cyan, amber and red light.
12. The device of claim 8 , wherein the brightness of the light produced by each color LED is controlled separately to vary the correlated color temperature.
13. The device of claim 8 , wherein the brightness of each different colored light produced by the color LEDs is controlled separately to vary the correlated color temperature.