Imaging unit

Abstract

An imaging unit includes a housing having an opening; a positioning portion provided in the housing; an imaging optical system including a bending optical system having two reflecting surfaces which bend an optical path of the imaging optical system, an incident surface of the bending optical system being exposed outwardly from the housing; an image sensor installed in the housing and includes an imaging surface which receives light reflected by one of the reflecting surfaces positioned on an exit side of the imaging optical system; a circuit board which closes at least part of the opening and to which the image sensor is fixedly connected; and a cover fixedly fitted to the housing so as to close the opening and press the circuit board toward the image sensor so that the image sensor or the circuit board comes in contact with the positioning portion.

1 . An imaging unit comprising:
 a housing having an opening;   a positioning portion provided in said housing;   an imaging optical system including first and second reflecting surfaces, provided on an incident side and an exit side of said imaging optical system, respectively, said first and second reflecting surfaces bending an optical path of said imaging optical system, wherein an incident surface of said imaging optical system is exposed outwardly from said housing;   an image sensor which is installed in said housing and includes an imaging surface which receives light reflected by said second reflecting surface;   a circuit board which closes at least part of said opening and to which said image sensor is fixedly connected; and   a cover, made of metal, which is fixedly fitted to said housing so as to close said opening and press said circuit board toward said image sensor so that one of said image sensor and said circuit board comes in contact with said positioning portion.   
     
     
         2 . The imaging unit according to  claim 1 , wherein a traveling direction of light which travels from said incident surface toward said first reflecting surface is opposite to a traveling direction of light reflected by said second reflecting surface. 
     
     
         3 . The imaging unit according to  claim 1 , wherein said cover comprises at least one pressure leaf which is resiliently deformable and presses said circuit board toward said image sensor. 
     
     
         4 . The imaging unit according to  claim 1 , wherein said opening is formed on one of opposite sides of said housing in the direction of thickness of said housing,
 wherein said image sensor comprises a flat cover glass which covers said imaging surface, and   wherein said positioning portion comprises at least one flat positioning surface which is orthogonal to said direction of thickness of said housing and with which said cover glass is in surface contact.   
     
     
         5 . The imaging unit according to  claim 4 , wherein said positioning portion comprises:
 a prism mounting recess which is open to said opening side; and   at least one positioning projection formed around said prism mounting recess, wherein said positioning projection projects toward said opening and includes said flat positioning surface at an end surface of said positioning projection,   wherein said imaging optical system comprises a prism which is installed in said prism mounting recess and reflects incident light toward said imaging surface, and   wherein said imaging unit further comprises a packing made of an elastic material which includes an exposing hole through which said imaging surface is exposed toward said prism side and a through-hole through which said positioning projection passes, said packing being held between said positioning portion and said image sensor.   
     
     
         6 . The imaging unit according to  claim 1 , wherein said housing comprises at least two engaging projections formed on two side surfaces positioned on opposite sides of said housing, and
 wherein said cover comprises corresponding at least two resilient engaging lugs having engaging holes in which said at least two engaging projections are disengageably engageable.   
     
     
         7 . The imaging unit according to  claim 1 , wherein said imaging optical system comprises a lens group that is movable along an optical path that is bent by said first reflecting surface,
 wherein said opening is formed entirely in one surface of said housing, and   wherein said movable lens group and said image sensor are installed in an internal space of said housing.   
     
     
         8 . The imaging unit according to  claim 1 , wherein said positioning portion is formed integral with said housing.