Asahi Kogaku Kogyo Kabushiki Kaisha

Nakamichi Corporation

Asahi Kogaku Kogyo K.k.

Showa Yakuhin Kako Co., Ltd.

501 Nakamichi Corporation

Yasunori Arai

Ryota Ogawa

Nobutaka Minefuji

Takashi Iizuka

Yoshihisa Inoue

Yoshihiro Yamazaki

Kazushi Yoshida

Takayuki Itoh

Michiro Ohishi

Tetsuya Abe

Minoru Suzuki

Hiroyuki Hirano

Yasuyuki Tejima

Ikuo Negoro

Jun Hirakawa

Hisao Iwanade

Motohiro Oka

Kazuo Ito

Shuichi Kobayashi

Kuniaki Asami

Kazuhiro Naganuma

Makoto Nagase

Michiro Oishi

Seiichi Sasaki

Sataro Takahashi

Takayuki Iizuka

An imaging optical system for compensating for changes of temperature according to the present invention corrects a focal point for an entire optical system due to temperature change by changing a relative distance between a lens and a light receiving element. To this end, a correcting member, which expands and contracts due to temperature change, is disposed between the lens and the light receiving element. Moreover, the coefficient of thermal expansion is set to such a value so as to be able to substantially correct for the focal point change. According to another aspect of the present invention, the optical system includes a lens system which has at least a positive lens and a negative lens in order to offset the effect of the temperature change.

Imaging optical system for compensating change of temperature

An optical holder for use in optical equipment, such as an astronomical telescope. The optical holder includes a barrel which has an inner peripheral wall. At least one optical article having an outer peripheral surface, such as a lens or a mirror, is mounted within the barrel. The inner peripheral wall of the barrel and the outer peripheral surface of the optical article are so sized as to provide a gap therebetween. The structure further includes a spacer, or spacers, that fit in the gap to hold the optical article in place. An annular spacer may be used or a plurality of spacers may be fit between the inner wall of the barrel and the optical article in a circumferentially spaced relationship. A shifting screw may also be used to shift the optical article within the barrel.

Structure for holding an optical article

A projection lens system which produces a smaller amount of residual chromatic aberrations and which will exhibit satisfactory performance even if it is used as a long-focus lens. The projection lens system is composed of a front group and a rear group. The front group includes, in order from the object side, a positive first lens element, a positive second lens element and a negative third lens element. The lens system satisfies the following conditions:

Projection lens system

In an imaging apparatus, a magnified image of an object is formed on a predetermined plane through a plurality of lens groups. A plurality of filters are selectively inserted into the light path between the object and the predetermined plane. An optical device is provided in the imaging apparatus, in which the plurality of lens groups are driven as a unit along the optical axis while the positional relation among the respective lens groups are correspondingly changed, wherein at least one of the plurality of lens groups is independently driven along the optical axis. The plurality of lens groups are driven to move in accordance with a desired image magnification, and at-least-one of the plurality of lens groups is independently driven, depending upon the selected filter, so as to place the object image on the predetermined plane.

Optical device

An image combining and projecting apparatus having a plurality of light transmission type image panels through which light beams are transmitted, condenser lenses corresponding to the light transmission type image panels, a beam combining mechanism which combines beams transmitted through the image panels, and a projection lens through which beams are projected after being combined by the beam combining mechanism, wherein the condenser lenses are provided on the light outgoing side of the corresponding image panels. The apparatus further has a condenser lens adjusting mechanism for adjusting the positions of the condenser lenses.

Apparatus for combining and projecting images

A magnifying projecting lens has a negative first lens group, a positive second lens group and a positive third lens group that is arranged in this order from a magnifying side. The lens groups are arranged so as to satisfy the following condition:

Magnifying projecting lens

A disc drive is particularly adapted to perform recording and/or reproducing operation with respect to a disc cartridge containing a magnetic optical disc. A known pick-up mechanism is mounted on a base which is, in turn, arranged above a main chassis via damper members for absorbing oscillation and vibration of the main chassis, which might otherwise be transmitted to the disc cartridge to affect the recording/reproducing operation. A loading chassis providing a cartridge accommodating space is arranged above the pick-up base and shiftable between an upper retracted position and a lower operative position, and more particularly it is moved to the lower position along with advancement of the disc cartridge whereas to the upper position along with advancement of a sliding plate arranged slidably with respect to the main chassis. There is provided a lock mechanism for retaining the sliding plate in the advanced position, which will be free from contact with any portion of the disc cartridge when inoperative to allow the sliding plate to protrude outside from the front panel. The sliding plate is provided with guide means which will be made operative during advancement of the sliding plate to ascend the loading chassis but, made inoperative and free from contact with any portion of the loading chassis when the latter is in the lower operative position.

Recording and/or reproducing apparatus with vibration isolation means

A disc drive particularly adapted to perform recording and/or reproducing operation with respect to a disc cartridge containing a magneto optical disc is composed of a main chassis for mounting thereon a pick-up mechanism, a loading chassis for accommodating the disc cartridge and vertically shiftable between its lower operative position and upper retracted position, a bias magnet mounted on the loading chassis for applying a magnetic field to the disc when the loading chassis is in the lower operative position, and a sliding plate slidably arranged on the main chassis for shifting the loading chassis between two positions along with sliding movement thereof. The bias magnet is shiftable substantially in a vertical direction with respect to the loading chassis and therefore separatable from the latter when the latter is in the upper retracted position for allowing smooth insertion of the disc cartridge.

Recording and/or reproducing apparatus having a vertically movable disk

In an electrophotographic copying apparatus, reflected light from an original subject is directed to a light receiving means, such as a photoconductive drum, through a slit. The apparatus includes an optical device, for example a zoom lens, positioned between the original subject and the photoconductive drum for varying the size of the optical image being passed through the slit. A shading board fixed adjacent to the photoconductive drum extends along a longitudinal direction of the optical image.

Shading board for copying apparatus

The present invention is a tear production measuring sheet that has a pair of measuring strips adapted to be used for the right and left eyes and is disposed side by side in such a manner that the strips have a common scale. Each of the measuring strips is separated from the measuring sheet by a cut formed in the measuring sheet so as to extend around the measuring strip, except for a connection between the measuring strip and the sheet.

Tear production measuring sheet and package therefor

A recording and/or reproducing apparatus includes a cartridge receiving holder, a cartridge shutter opening device for opening a laterally slideable shutter of a disc cartridge along with insertion thereof into the holder, a mount base displaceable between a retracted position away from the holder and an operative position in which a head and spindle motor mounted on the base will be made operative with respect to a disc contained in the full-loaded disc cartridge in the holder. The disc cartridge is retained in the full-loaded position in the holder through engagement between a lock lever rotatably mounted on the holder and a notch formed on the side periphery of the disc cartridge. The lock lever is normally biased by a spring to direct outwardly so that the disc cartridge is free from contract with the lock lever during insertion into the holder. When the disc cartridge has reached the full-loaded position, a sliding plate is sprung back toward a direction opposite to the cartridge inserting direction, upon which the lock lever is actuated and then the mount base is shifted to the operative position.

Recording and/or reproducing apparatus with cartridge lock mechanism

A device for opening a shutter of a disc cartridge along with insertion of the disc cartridge into a holder of a recording and/or reproducing apparatus for performing recording and/or reproducing operation is disclosed. The device includes at least one arm member freely rotatable about a pivot provided at one end thereof and having at the other end a first engaging portion adapted to be in engagement with the shutter substantially during insertion of the disc cartridge. A guide means or a slot extending in an oblique direction between the cartridge inserting direction and a direction in which said shutter is slided to open is provided for guiding therealong a second engaging portion of the arm member during first-step advancement of the disc cartridge into the holder from an unloaded position to a half-loaded position, thereby rotating the arm member to open the shutter due to continued engagement thereof with the first engaging portion. The pivot of the arm member is supported by a sliding member and is sliding therewith in the cartridge inserting direction during second-step advancement of the disc cartridge from the unloaded position to a full-loaded position. A spring is connected between the arm member and the holder or apparatus for biasing the arm member toward a direction opposite to the cartridge inserting direction.

Cartridge shutter actuating device in recording and/or reproducing

An optical device for varying magnification, having an object plane on which an object is to be located, a light receiving surface, and an imaging lens unit for focusing an image of the object located on the object plane onto the light receiving surface, so that upon varying the magnification, an optical distance between the object plane and the light receiving surface can be changed, wherein the imaging lens unit includes a main lens group and a correcting lens group that are movable relative to each other, the main lens group or the correcting lens group being fixed with respect to the light receiving surface, the correcting lens group or the main lens group being movable to the object plane and the light receiving surface to vary the magification.

Optical device for varying magification

A device for opening a shutter of a disc cartridge along with insertion of the disc cartridge into a holder of a recording and/or reproducing apparatus for performing recording and/or reproducing operation is disclosed. The device includes at least one arm member freely rotatable about a pivot provided at one end thereof and having at the other end a first engaging portion adapted to be in engagement with the shutter substantially during insertion of the disc cartridge. A guide means or a slot extending in an oblique direction between the cartridge inserting direction and a direction in which said shutter is slided to open is provided for guiding therealong a second engaging portion of the arm member during insertion of the disc cartridge, thereby rotating the arm member to open the shutter due to continued engagement thereof with the first engaging portion. The pivot of the arm member is supported by a sliding member and is moving while the second engaging portion is being guided along the first guide means. A spring is connected between the arm member and the holder or apparatus for biasing the arm member toward a direction opposite to the cartridge inserting direction.

A long focal length, super-large aperture ratio reflecting/refractive optical system employing easily workable spherical surfaces and which is suitable for use in an astrocamera or a super-telephoto lens system. The lens system includes four optical units arranged along the optical path, including a first optical unit composed of a meniscus lens having a weak negative power, a second optical unit composed of a reflecting surface having a positive power, a third optical unit for deflecting light reflected from the second optical unit, and a fourth optical unit including at least one negative lens element.

Growing community of inventors

Tokyo, Japan

Yasunori Arai