Abstract: To the female helicoidal screw of the lens barrel (outer barrel body), there is always imparted a biasing force from a plurality of looseness eliminating springs formed on the outside peripheral portion of the lens barrel (inner barrel body) which are integrally supported on the lens barrel (inner barrel body), by means of the male helicoidal screw, and the male helicoidal screw is slid while being thrusted against the female helicoidal screw.

Abstract: A rod integrator includes a quadrangular prismatic light-guiding member with a rectangular cross-sectional shape. The light-guiding member guides a light beam from a first end surface to a second end surface, opposing the first end surface, while the beam is reflected by the side surfaces so that the beam is output from the second end surface. The rod integrator includes a tube-shape body having the first open end portion tightly surrounding the end portion of the light-guiding member on the side of the second end surface, and having the second open end portion from which the beam is output while causing the beam from the first end portion to be reflected by inner mirror surfaces of the tube-shape body. The tube-shape body is arrangedy in a pinwheel shape. First, second, third, and fourth members, each of which has a plate shape and a mirror surface on one side, are arranged on the light-guiding member, such that the tube-shape body has the mirror surfaces facing inside.

Abstract: To the female helicoidal screw of the lens barrel (outer barrel body), there is always imparted a biasing force from a plurality of looseness eliminating springs formed on the outside peripheral portion of the lens barrel (inner barrel body) which are integrally supported on the lens barrel (inner barrel body), by means of the male helicoidal screw, and the male helicoidal screw is slid while being thrusted against the female helicoidal screw.

Abstract: A rod integrator includes a quadrangular prismatic light-guiding member with rectangular cross-sectional shape. The light-guiding member guides the beam from the first end surface to the second end surface opposing the first end surface while causing the beam to be reflected by the side surfaces such that the beam is outputted from the second end surface. The rod integrator includes a tube-shape body having the first open end portion tightly surrounding the end portion of the light-guiding member on the side of the second end surface, and having the second open end portion from which the beam is outputted while causing the beam from the first end portion to be reflected by inner mirror surfaces of the tube-shape body. The tube-shape body is arranged, in a pinwheel shape, a first, second, third, and fourth member, each of which is in plate shape and has a mirror surface on one side, onto the light-guiding member, such that the tube-shape body has the mirror surfaces facing inside thereof.

Abstract: A rod integrator comprises a solid rod-shaped first member and a hollow second member. The first member guides a luminous flux from a light source incident on one end to the other end while totally reflecting the luminous flux on side faces. The second member guides the luminous flux from the first member incident on one end to the other end while specularly reflecting the luminous flux, and then emits the luminous flux from the other end. The first and second members are combined such that substantially all of the luminous flux emitted from the other end of the first member is made incident on one end of the second member.

Abstract: A microfilm reader which has an optical system for magnifying and projecting an image recorded on a film contained a cassette onto a viewing screen mounted on a pivot shaft of a casing having a generally rectangular flattened box-like configuration of the microfilm reader for folding and unfolding movement comprises a cassette holder, a microfilm driving device for transporting the microfilm so as to place a frame of the microfilm of which an image is to be projected, a reflection mirror supported by the casing for sliding movement so as to be foldable in order to turn the projected image toward the viewing screen, a top cover mounted on and supported by the casing for folding and unfolding movement which is slidably engaged with a top end of the viewing screen so as to define a dark space behind the viewing screen in cooperation therewith when the viewing screen is unfolded and to cover and protect the viewing screen when the viewing screen is folded, and linking device interconnecting the viewing screen and

Abstract: A microfilm reader which has an optical system for magnifying and projecting an image recorded on a film contained a cassette onto a viewing screen mounted on a pivot shaft of a casing having a generally rectangular flattened box-like configuration of the microfilm reader for folding and unfolding movement comprises a cassette holder, a microfilm driving device for transporting the microfilm so as to place a frame of the microfilm of which an image is to be projected, a reflection mirror supported by the casing for sliding movement so as to be foldable in order to turn the projected image toward the viewing screen, a top cover mounted on and supported by the casing for folding and unfolding movement which is slidably engaged with a top end of the viewing screen so as to define a dark space behind the viewing screen in cooperation therewith when the viewing screen is unfolded and to cover and protect the viewing screen when the viewing screen is folded, and linking device interconnecting the viewing screen and