Projection type image display apparatus with shielded circuit board
View Patent ↗The projection type image display apparatus is equipped with a lamp unit ( 22 ), an optical block ( 21 ) which modulates light from the lamp unit and projects an image signal, a circuit board ( 24 ) having via holes and on which an external connector ( 25 ) is mounted, and a cabinet ( 2 ) for housing the aforementioned elements. The display apparatus is equipped with a back cover ( 26 ) provided to cover around the external connector from the outside and a dustproof cover ( 29 ) provided to cover around the external connector from the inside. A closed space is formed by the circuit board, the back cover ( 26 ) and the dustproof cover ( 29 ), and the dustproof cover closely shields at least a space below the circuit board from the exterior. Excellent dustproof characteristics enabling use even in installation environments with a large amount of dust and dirt can be obtained.
1. A projection type image display apparatus comprising a light source, an optical component that modulates light from the light source and projects an image signal, a circuit board that has via holes and on which a plurality of external connectors are mounted, and a cabinet that houses the aforementioned elements;
the projection type image display apparatus further comprising
a single connector cover provided to cover the plurality of external connectors so that a tip end part of each of the external connectors is exposed respectively to the outside, and
a single dustproof cover provided for the external connectors opposing the connector cover, the dustproof cover having a base member from which a solid peripheral wall extends, the base member having a peripheral portion where the peripheral wall is not present that defines a first edge, the peripheral wall defining a second edge in a plane that is spaced from the base member and third and fourth edges that extend between the first edge and the second edge,
the second edge engaging the circuit board, and the first, third and fourth edges engaging the connector cover to define a closed space enclosing the plurality of external connectors,
whereby dust and dirt entered from a clearance between the tip end part of each of the external connectors and the connector cover are prevented from further entering into an area of the optical component by the presence of the closed space.
2. The projection type image display apparatus according to claim 1 , further comprising an elastic dustproof sheet provided between the circuit board and an outer cover that composes a part of the cabinet so as to cover the circuit board, for shielding through holes other than the via holes on the circuit board and for shielding a clearance between the circuit board and the connector cover.
3. The projection type image display apparatus according to claim 1 , wherein the via holes formed on the circuit board in an area corresponding to the closed space are clogged.
4. The projection type image display apparatus according to claim 1 , wherein the dustproof cover is formed of a resin material.
5. The projection type image display apparatus according to claim 1 , wherein the via holes are clogged by solder application conducted using a solder application mask having a pattern for the solder application including positions of the via holes.