A phosphor for low-pressure discharge lamps is disclosed, wherein the phosphor is present in the form of phosphor grains coated with a protective layer, wherein the protective layer consists of a metal oxide, a metal borate, a metal phosphate or mixtures thereof.

A light-emitting device includes a light-emitting element for emitting primary light, and a wavelength conversion unit for absorbing part of the primary light and emitting secondary light having a wavelength longer than that of the primary light, wherein the wavelength conversion unit includes plural kinds of phosphors having light absorption characteristics different from each other, and then at least one kind of phosphor among the plural kinds of phosphors has an absorption characteristic that can absorb the secondary light emitted from at least another kind of phosphor among the plural kinds of phosphors.

An LED pump light with multiple phosphors is described. LEDs emitting radiation at violet and/or ultraviolet wavelengths are used to pump phosphor materials that emit other colors. The LEDs operating in different wavelength ranges are arranged to reduce light re-absorption and improve light output efficiency.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image.

A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.

An LED pump light with multiple phosphors is described. LEDs emitting radiation at violet and/or ultraviolet wavelengths are used to pump phosphor materials that emit other colors. The LEDs operating in different wavelength ranges are arranged to reduce light re-absorption and improve light output efficiency.

According to one embodiment, a white light source includes a combination of a light emitting diode and phosphors. One of the phosphors is at least a cerium activated yttrium aluminum garnet-based phosphor. There is no light emission spectrum peak at which a ratio of a largest maximum value to a minimum value is greater than 1.9. The largest maximum value is largest among at least one maximum value present in a wavelength range of 400 nm to 500 nm in a light emission spectrum of white light emitted from the white light source. The minimum value is adjacent to the largest maximum value in a longer wavelength side of the light emission spectrum.

A light emitting device is disclosed. The light emitting device includes: a light emitting diode emitting light having a peak wavelength in the range of 415 nm to 435 nm; and a wavelength conversion unit disposed on the light emitting diode, wherein the wavelength conversion unit includes cyan phosphors emitting light having a peak wavelength in a cyan light wavelength band and red phosphors emitting light having a peak wavelength in a red light wavelength band, and a ratio of an output of light having a wavelength in the range of 435 nm to 465 nm to a total output of light emitted from the light emitting device is approximately equal to or less than 3%.

A phosphor is represented by the general formula

aM.sup.IX.M.sup.II.sub.1-xM.sup.IM.sup.VO.sub.4:(Re).sub.x

where M.sup.I is at least one atomic element selected from the group consisting of K, Li, Na, Rb, Cs, Fr, Cu, and Ag, with K being essential; M.sup.II is at least one atomic element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Mn, Zn, Cd, and Sn; M.sup.V is at least one atomic element selected from the group consisting of P, V, Nb, Ta, As, Sb, and Bi; X is at least one halogen element, with F being essential; Re is at least one atomic element selected from the group consisting of rare earth elements, with Eu being essential; and a is in the range 0.6a1.4.

A light emitting device includes: a first white light source which includes N pieces of first white light emitting diodes and emits a first white light; and a second white light source which includes M pieces of second white light emitting diodes and a first resistance element electrically connected in series to the second white light emitting diodes and having a first resistance value, is electrically connected in parallel to the first white light source, and emits a second white light, the light emitting device emitting a mixed white light of the first white light and the second white light. The drive voltage of the first white light source is higher than a drive voltage of the second white light source, and a color temperature of the mixed white light is higher as a total luminous flux of the mixed white light is higher.

To provide a semiconductor light emitting device which is capable of accomplishing a broad color reproducibility for an entire image without losing brightness of the entire image. A light source provided on a backlight for a color image display device has a semiconductor light emitting device comprising a solid light emitting device to emit light in a blue or deep blue region or in an ultraviolet region and phosphors, in combination. The phosphors comprise a green emitting phosphor and a red emitting phosphor. The green emitting phosphor and the red emitting phosphor are ones, of which the rate of change of the emission peak intensity at 100 C. to the emission intensity at 25 C., when the wavelength of the excitation light is 400 nm or 455 nm, is at most 40%.