Image projection devices that utilize a light bulb to illuminate a slide transparency or film in combination with a lens to enlarge the image onto a viewing surface are well known. Slide projectors for viewing 35 mm slides came into widespread use during the 1950s for home entertainment and educational uses. These slide projectors included an electric incandescent light bulb or other light source, a condensing lens or reflector to direct light onto the slide, a slide holder, and a focusing lens. Slide projectors have fallen out of use in favor of more convenient digital media shown on a projection screen using a video projector or displayed on a large video monitor.
Flashlight projectors are a novelty or toy item that use a flashlight as the light source to illuminate a slide transparency. These devices typically include a mechanism to attach to the flashlight, a mechanism to mount the slide in position, and optics to focus and enlarge the slide image. Examples include U.S. Pat. Nos. 2,445,651, 2,478,336, and 5,321,449.
Mobile devices, such as smart phones, digital cameras and tablet computing devices, can also be equipped with an image projector. This type of technology typically uses a liquid crystal on silicon display with a light source, such as a light emitting diode (LED), for example, to illuminate the display. Adding an image projector to a mobile device can significantly increase the costs of producing the mobile device. For example, U.S. Pat. No. 7,874,683 discloses the use of a transmissive liquid crystal panel and an LED light source that are integrated within the mobile device. The LED light source illuminates the transmissive liquid crystal panel and an external projection lens, which can be removably fitted or integral with the mobile device, magnifies and projects the image from the transmissive liquid crystal panel onto a screen.
U.S. Patent Application No. 2015/0323160 discloses an entertainment accessory device that can be coupled to a smartphone to position a projection member in the path of light from the LED of the smartphone. The entertainment device can include multiple projection members of different colors or effects integrated onto a rotating dial to allow a user to create multiple different types of lighting projections and effects. The entertainment device can also respond to sounds, such as music, to change light effects. The projection member can be engraved or have a graphic design printed thereon. This design does not allow for the projection of photograph quality images because of the integration of the graphics with the projection member and the lack of conditioning of the LED light source.