|Home theater systems|
|Wednesday, 25 October 2006|
A typical home theater system combines video capabilities with advanced audio systems. A home theater system generally includes an A/V receiver to which a number of audio and video components may be attached. These components may include video cassette recorders (VCR), digital video disc (DVD) players, televisions (e.g., a high-definition or a digital television), compact disc (CD) players, audio/visual (A/V) receivers, tuners, equalizers, headphones, satellite speakers, center channel speakers, woofers, and/or subwoofers disposed in a fixedly mounted rectanguloid housing. In a home theater system, a screen image is projected on a big screen in cooperation with acoustic effects in a delicate, highly real, and powerful manner, delivered from multichannel speakers, e.g., 5.1 channel speakers, which correspond to the screen image so that spectators can enjoy a screen image and acoustic effects which cannot be achieved by a conventional audio system. Home theater systems are conveniently operated using remote controls. These remote controls typically use infrared light and special device codes to transmit commands to particular entertainment systems. Each remote/device pair usually uses a different device code, which prevents signals from being crossed. Some home theater systems comprise highly specialized installation/orientation features such as a laser-based alignment tool being magnetically attached to a base plate, stacker discs for incrementally varying the height of the base plate, a speaker baffle, a beam splitter, a line lens, and a protractor plate.
A home theater system is adjusted to reproduce sound having a high presence similar to that realized by sound system of a movie theater. In addition to a well-equipped video system, such as a digital versatile disk (DVD) drive and a wide-screen television, a typical home theater system also includes a sophisticated audio system, which may include a surround sound audio system, so that the home audience can experience various sound effects from a movie presented by the home theater system as if the home audience were in a theater. Typical surround sound systems incorporate at least five speakers: front right and left speakers, rear right and left speakers and a front center speaker, requiring that a number of loudspeakers be placed throughout the viewing room in order to achieve the desired audio effects. A surround amplifier is provided for extracting the surround channels from the incoming signal. Surround amplifiers are typically based on the Dolby chip. Most amplifiers have DSP (digital signal processor) capabilities, which can modify the sound of a non-surround music source to sound as if it originates from different artificial acoustic environments, such as a concert hall, a theater, a jazz club, etc. The room itself has to be modified to fit the home theater requirements. Since there are many different sound sources in the room, any unwanted echo destroys the sound quality and directionality. The room must therefore be covered with acoustically absorbing materials, such as carpets and drapes. Acoustical isolating materials must be used to avoid disturbing neighbors.
The quality of sound and video experienced in home entertainment systems or other audiovisual systems today is mostly determined by the quality of the components in the final stage of the signal path: the speakers and the display devices. A modern home theater system may comprise a large screen television. Digital televisions (DTV) and high-definition televisions (HDTV) are gaining popularity in today's consumer electronics marketplace. The combination of a DTV (or HDTV) and a digital video recorder or player can be an integral part of a home theater entertainment system. Most home theater systems are equipped with image projectors to display a movie in a home theater environment. A projector is an image projection apparatus showing images by projecting inputted image signals onto screens. Such an image projection apparatus is mainly employed in home theater systems. Projectors for home theaters are typically liquid crystal projectors that use liquid crystal display elements, and digital light processing (DLP) projector that uses a digital mirror device (DMD). A DLP projector eliminates the pixel mosaic problem of a liquid crystal display (LCD) projector and delivers a higher contrast ratio so as to enhance original color reproducibility.