1. Field of the Invention
The invention relates to a projector, and more particularly to a projector having retractable housings to reduce the noises.
2. Description of the Related Art
Recently, a projector has become an indispensable apparatus in the teaching or meeting occasions. More particularly, with the popularization of the notebook computers, the digital projector is more suitable for the above-mentioned occasions.
The projector needs a light source with high brightness so as to clearly project images onto a display screen. However, the light source with high brightness may cause a high-temperature condition in the projector. Therefore, the currently used projector needs a fan to dissipate heat generated from the light source, which is the main heat source in the projector, control the proper thermal flow field, and prevent high temperature environment from damaging the electronic elements and optical elements in the projector.
Recently, the volume of the projector is getting smaller and smaller. However, if the volume of the projector is reduced, the redundant space within the projector has to be removed. In this case, the hot air streams are directly exhausted at high speed to cause great noises because no more slowdown space for the air streams is left in the projector.
FIG. 1 is a schematic top view showing a conventional projector, and FIG. 2 is a side view showing the projector of FIG. 1. Referring to FIGS. 1 and 2, the projector includes a casing 110, a light source 128, an optical engine 130, fans 120 and 122, and a plurality of circuit boards 132. The casing 110 is formed with inlet ports 112 and 114, through which air streams 124 may flow into the casing 110, and outlet ports 116 and 118, through which the air streams 124 may flow out of the casing 110. The light source 128, which is the main heat source, emits light rays to the optical engine 130. Then, the optical engine 130 processes the light rays and projects an image onto a display screen. The fans 120 and 122 introduce the air streams 124 into the casing 110 through the inlet ports 112 and 114 and dissipate heat from the outlet ports 116 and 118.
A buffer chamber 126, which is defined among the fan 120, casing 110 and outlet ports 116, may be regarded as a slowdown space for the air streams 124 from the buffer chamber 126 to the casing 110. When a designer wants to reduce the volume of the projector, it is possible to consider that the buffer chamber 126 may be reduced so as not to influence the normal functions of the projector. However, reducing the buffer chamber 126 may reduce the slowdown space for the air streams 124 and cause the air streams 124 to flow out via the outlet ports 116 at high speed. In this case, relatively great noises may be generated.
An object of the invention is to provide a projector capable of reducing noises.
Another object of the invention is to provide a miniaturized projector that is portable and causes smaller noises.
To achieve the above-mentioned objects, the invention provides a projector including a casing, a light source, an optical engine, inlet ports and outlet ports formed on the casing, and a fan mounted in the casing. The fan sucks air streams from the inlet ports into the casing and forces the air streams to flow out of the casing via the outlet ports. A buffer chamber is defined among the fan, the outlet ports, and the casing. The casing includes a first housing and a second housing. The first housing is retractable relative to the second housing so that a volume of the buffer chamber may be changed.
The projector may further include a light source mounted to the casing and positioned between the inlet ports and the fan. In addition, the projector may further include a rack attached to the first housing, and a driving gear for driving the rack so as to move the first housing.
The inlet ports and the outlet ports may be formed on the second housing and the first housing, respectively. The first housing is retractable relative to the second housing along a direction perpendicular or parallel to a direction of the air streams or along an arbitrary direction.