1. Field of the Invention
The present invention relates to a projection apparatus, such as a projector. More specifically, the present invention relates to a focus regulator of a projection apparatus for adjusting the focus of an image projected onto a screen.
2. Description of the Related Art
Conventionally, a projection apparatus is a displaying device designed for enlarging and projecting an optical image generated from an image formation unit onto a projection surface, such as a screen.
The projection apparatus generally includes an illuminating optical system for generating light, an image formation unit for converting the light generated by the illuminating optical system into an optical image, and a projection system for enlarging and projecting the optical image converted by the image formation unit onto a projection surface. Additionally, the projection system includes a first lens unit for an incident optical image generated by the image formation unit, and a second lens unit for projecting an optical image passing through the first lens unit onto a projection surface.
Additionally, the projection apparatus includes a focus regulator for adjusting the focus of the optical image enlarged and projected onto the projection surface. The focus regulator adjusts the focus of the optical image by changing the interval between the first and second lens units.
A conventional focus regulator includes a controller protruding outside of a main body of the projection apparatus for easy controlling by a user, and a power transmission unit for transmitting power from the controller to the first lens unit. Operation of the focus regulator having the above configuration is started by a user rotating the controller. Then, the rotation of the controller is transmitted by the power transmission unit and causes a rotation of the first lens unit. The first lens unit moves in the direction of the optical axis of the optical image by the rotation. The movement of the first lens in the direction of the optical axis adjusts the interval between the first and second lens units, thereby adjusting the focus of the projected image. Additionally, the controller moves in the direction of the optical axis together with the first lens unit.
However, when the controller moves in the direction of the optical axis, additional space inside the projection apparatus is necessary for accommodating the movement of the controller. In particular, because the controller is protruded outside of a main body of the projection apparatus for easy controlling by a user, a design for assuring the necessary space becomes more difficult. Additionally, providing this space hinders minimization of the projection apparatus.
In particular, as the demand for a portable projection apparatus increases, developing a focus regulator having a simple structure and being advantageous to the minimization of the apparatus also becomes necessary.
Additionally, as the importance of the design for the projection apparatus grows, a mask, fixedly installed on a main body of the projection apparatus, is used for covering the front of the main body. However, when the focus regulator described above is used, designing the mask is difficult as it should not restrict movement of the controller back and forth.
Accordingly, a need exists for an improved projection apparatus having a focus regulator while minimizing the size of the projection apparatus.