Electronic flash, imaging device and method for producing a flash of light having a wavelength spectrum in the visible range and the infrared range using a fluorescent material

#Electronic flashes provide supplemental light for photography to enhance images captured by a camera or other imaging devices. Traditional electronic flashes utilize a bulb filled with gas, such as argon, krypton, neon and xenon, or vapor, such as mercury vapor. When a high voltage is applied to the bulb, the gas or vapor is ionized, allowing electrons to flow through the gas or vapor. These electrons excite the atoms of the gas or vapor, which emit light. The wavelength characteristics of the emitted light depends on the gas or vapor in the bulb. In the case of mercury vapor, the emitted light is ultraviolet light, which is usually converted to visible light using fluorescent material since ultraviolet light is typically not desired.

#Recently, light emitting diode (“LEDs”) have been improved to a point with respect to operating efficiency where LEDs are now replacing conventional light sources, even bulbs in electronic flashes. Existing LEDs can emit light in the ultraviolet (“UV”), visible or infrared (“IR”) wavelength range. These LEDs generally have narrow emission spectrum (approximately +/−10 nm). As an example, a blue InGaN LED may generate light with wavelength of 470 nm+/−10 nm. As another example, a green InGaN LED may generate light with wavelength of 510 nm+/−10 nm. As another example, a red AlInGaP LED may generate light with wavelength of 630 nm+/−10 nm. However, since electronic flashes typically need to produce white light for color rendering purposes, different color LEDs such as red, blue and green LEDs are used together in an electronic flash to produce white light. Alternatively, a fluorescent material is introduced into one or more UV, blue or green LEDs in an electronic flash to produce with light using fluorescence.

#For different photographic applications, different wavelength characteristics are desired from the supplemental light provided by the electronic flash. Thus, there is a need for an electronic flash, imaging device and method for producing a flash of light in which the color characteristics of the light can be adjusted.

#FIG. 1 shows an electronic flash in accordance with an embodiment of the invention, which may be included in an imaging device or an external flash unit.

#FIG. 2 is a diagram of a digital imaging device with an integrated electronic flash in accordance an embodiment of the invention.

#FIG. 3 is a diagram of an LED with an emission spectrum in the visible wavelength range and the infrared (IR) wavelength range in accordance with an embodiment of the invention.

#With reference to FIG. 1, an electronic flash 10 for use in photography in accordance with an embodiment of the invention is described. The electronic flash 10 utilizes at least one light source device that produces an output light having a broad wavelength spectrum in both the visible wavelength range and the infrared (IR) wavelength range. Thus, the electronic flash 10 is capable of providing a flash of light having desired wavelength characteristics in which at least one component of the flash of light has a broad UV/visible wavelength spectrum.

#As shown in FIG. 1, the electronic flash 10 may be included in a digital camera 12, a camera phone 14 or any other imaging device, which is sensitive to both visible and IR light. The electronic flash 10 may also be included in an external flash unit 16 that can be used in connection with an imaging device. The external flash unit 16 may be designed to be attached an imaging device or to be used as an external device in connection with an imaging device. The electronic flash 10 is described in more detail below with reference to FIG. 2.

#In FIG. 2, a digital imaging device 20 with the electronic flash 10 in accordance an embodiment of the invention is shown. In this embodiment, the electronic flash 10 is incorporated into the digital imaging device 20. The digital imaging device 20 is described herein as a digital camera that is sensitive to both visible and IR light. However, the imaging device 20 can be any imaging device that is sensitive to both visible and IR light, such as a digital video camera.