Screen unit

Abstract

A screen unit includes: a screen which has a first side and a second side opposing to each other in a first direction and extending substantially in parallel with each other; a first supporting portion extending along the first side to support the first side; a second supporting portion extending along the second side to support the second side; and a plurality of connecting mechanisms each of which extends between the first supporting portion and the second supporting portion, and expands and contracts in the first direction to move the second supporting portion close to and away from the first supporting portion, wherein the plurality of connecting mechanisms are disposed in parallel with the first supporting portion, and are located almost linearly symmetric with respect to a center line connecting approximately the center of the first side and approximately the center of the second side.

1 . A screen unit comprising:
 a screen which has a first side and a second side disposed opposed to each other and extending substantially in parallel with each other;   a first supporting portion extending along the first side of the screen to support the first side;   a second supporting portion extending along the second side of the screen to support the second side; and   a plurality of connecting mechanisms each of which extends between the first supporting portion and the second supporting portion, and expands and contracts in the direction in which the first supporting portion and the second supporting portion are opposed to move the second supporting portion close to and away from the first supporting portion,   wherein the plurality of connecting mechanisms are disposed in parallel in the direction in which the first supporting portion and the second supporting portion extend, and are located almost linearly symmetric with respect to a center line connecting approximately the center of the first side in the extending direction of the first side and approximately the center of the second side in the extending direction of the second side.   
     
     
         2 . The screen unit according to  claim 1 , wherein the plural connecting mechanisms include a plurality of first connecting mechanisms disposed as a pair or pairs on both parts of the screen unit with the center line interposed therebetween. 
     
     
         3 . The screen unit according to  claim 2 , wherein
 the plural connecting mechanisms include a pair of the first connecting mechanisms; and   the pair of the first connecting mechanisms have almost linearly symmetric structures with respect to the center line as viewed in the normal line direction of a projection surface of the screen.   
     
     
         4 . The screen unit according to  claim 3 , wherein
 the first supporting portion includes a pair of fixed supports provided at predetermined positions and a pair of movable supports movable in the extending direction of the first supporting portion in correspondence with the pair of the first connecting mechanisms;   the second supporting portion includes a pair of fixed supports provided at predetermined positions and a pair of movable supports movable in the extending direction of the second supporting portion in correspondence with the pair of the first connecting mechanisms;   the respective first connecting mechanisms are connected with the respective fixed supports and the respective movable supports of the first supporting portion and with the respective fixed supports and the respective movable supports of the second supporting portion; and   each pair of the fixed supports of the first supporting portion, each pair of the movable supports of the first supporting portion, each pair of the fixed supports of the second supporting portion and each pair of the movable supports of the second supporting portion are disposed almost linearly symmetric with respect to the center line.   
     
     
         5 . The screen unit according to  claim 4 , wherein the pair of the fixed supports of each of the first supporting portion and the second supporting portion are disposed outside the pair of the movable supports of the corresponding supporting portion with respect to the center line. 
     
     
         6 . The screen unit according to  claim 5 , further comprising:
 a rotating mechanism which has a rotation shaft extending along the first supporting portion,   wherein   each of the pair of the movable supports of the first supporting portion has a screw portion which has a female screw formed coaxially with each other,   the rotation shaft is inserted through the screw portions of the pair of the movable supports of the first supporting portion and has a male screw engaging with the screw portions, and   one of the screw portions of the pair of the movable supports is a right-handed screw, and the other of the screw portions of the pair of the movable supports is a left-handed screw.   
     
     
         7 . The screen unit according to  claim 5 , further comprising:
 a rotating mechanism which has a rotation shaft disposed between the pair of the movable supports of the first supporting portion,   wherein   one of the pair of the movable supports is connected with the rotation shaft via a first wire, and the other of the pair of the movable supports is connected with the rotation shaft via a second wire, and   the first wire and the second wire are wound or returned in accordance with the rotation direction of the rotation shaft to shift the pair of the movable supports in directions opposite to each other along the first supporting portion.   
     
     
         8 . The screen unit according to  claim 6 , wherein the rotating mechanism has an electrically operated motor which rotates the rotation shaft. 
     
     
         9 . The screen unit according to  claim 2 , wherein the plural connecting mechanisms further include a second connecting mechanism disposed on the center line.