Abstract: In a magnetic recording medium such as video tape, audio tape and computer tape, comprising a non-magnetic support and a magnetic recording layer coated thereon in which a ferromagnetic powder is dispersed, the feature consists in that the binder contains a polyisocyanate and at least one isocyanate reaction accelerating compound selected from the group consisting of (1) tertiary amine compounds, (2) tin compounds, (3) organometallic compounds except tin compounds, (4) amphoteric ion compounds and (5) organic acids. The stability and abrasion resistance are largely improved.

Abstract: A flash device for a camera having a light emitting window of rectangular shape oriented so that the long side of the window is nearly perpendicular to a long side of the film format in the camera. An optical panel in the light emitting window is constructed in such a way as to satisfy the following conditions:0.5<f1/f<1.5f2/f<0.5,where f1 is the focal length of an end portion of the longitudinal length of the optical panel, f2 is the focal length of a central portion of the optical panel, and f is the focal length of a photographic lens of the camera.

Abstract: In the disclosed beam splitter, a first prism has an entrance face, an inclined face, and a mirrored face for totally reflecting a beam reflected from the inclined face back to the inclined face. A second prism has an entrance face in parallel with the inclined face of the first prism, and two exit faces. One of the exit faces of the second prism cooperates with the mirrored face of the first prism. When the first and second prisms are turned as a unit, the inclined face of the first prism either passes a light beam arriving from the entrance face through to the second prism and out one of the exit faces or totally reflects the arriving light beam to the mirrored face. The light beam reflected back from the mirrored face now passes through the inclined face to the second prism and out the cooperating exit face of the second prism.

Abstract: The disclosed compact photographic lens includes, from front to rear, a positive meniscus-shaped first lens unit convex toward the front, a negative aspheric second lens unit concave toward the front, a bi-concave third lens unit, and a negative fourth lens unit with its front surface concave toward the front. The lens satisfies the following conditions:-3.5<r3/f<-2.0-1.8<r7/f<-0.51.4<r8/f<6.50<d6/f<0.017where f is the focal length of the entire system, r3 is the paraxial radius of curvature of the front surface of the third lens unit, r7 and r8 are the radii of curvature of the front and rear surfaces of the fourth lens unit respectively, and d6 is the axial air separation between the third and fourth lens units when focused to infinity.

Abstract: An objective lens comprising a front lens unit and a rear lens unit with the separation between the two lens units being varied to vary the focal length of the entire system, wherein the front lens unit has a positive refractive power and consists of a positive lens of strong convex curvature toward the front, a negative doublet lens of a negative lens and a positive lens cemented together in this order from the front, and a positive lens sub-unit, and the rear lens unit has a negative refractive power and comprises a positive lens and a negative lens. Particularly the double lens is so designed that the comatic aberration in the intermediate zone of the image frame is stabilized throughout the entire range of variation of the focal length, and the halo in the intermediate zone in the telephoto end is well corrected.

Abstract: A magnetic recording medium comprising a magnetic layer on a non-magnetic base, said magnetic layer containing ferromagnetic particles and a binder comprising (a) a copolymer of at least vinyl chloride and vinyl acetate, (b) a synthetic rubber selected from the group consisting of diolefinic and olefinic synthetic rubbers and (c) a resin selected from the group consisting of phenoxy resin and polyhydroxy ether ester resin.

Abstract: The disclosed zoom lens is constructed with a front lens group including, from front to rear, a positive lens unit, a negative lens unit and a positive lens unit having a positive overall refractive power. A rear lens group having a negative overall refractive power arranged on the image side of the front lens group moves axially along with the front lens group in differential relation. The rear lens group is constructed with a negative front lens having a glass relatively large Abbe number and a positive rear lens having a glass of relatively small Abbe number to achieve good stability of chromatic aberration correction against zooming.

Abstract: A compact zoom lens is constructed with, from front to rear, first, second and third lens units of positive, negative and positive refractive powers, respectively. A diaphragm is positioned in or adjacent the second lens unit. The second lens unit and the diaphragm are stationary. When zooming from the wide angle end to the telephoto end, the first and third lens units are axially moved in such a manner that each of the separations between the first and second lens units and between the second and third lens units is increased monotonically.

Abstract: A conversion lens upon attachment on the image side of a master lens increases the focal length of the entire system. The conversion lens comprises three components of negative, positive and negative powers in this order from the front, has a negative power as a whole, and satisfies the following conditions:2.0<f1/f3<4.00.8<.vertline.f2/f3.vertline.<1.2n1-n2>0.15where fi and ni are the focal length and the refractive index of the glass of the i-th component counting from the front respectively.

Abstract: A portable and wearable injector of mini size is disclosed, which may be operated for injection by means of a gas pressure and which is equipped with an injector syringe and a gas-impermeable flexible bag received in the syringe having one open end for injection and the other sealed end. The bag contains therein a gas-generating device for producing a pressure gas for expanding the bag in order to urge an infusion liquid through the open end of the syringe. As the gas-generating device there may be used an electric or chemical device.

Abstract: A conversion type varifocal lens system comprising a master lens which has a front assembly of positive power and a rear assembly of negative power, and a supplementary lens upon insertion into, or removal from, the space between the front and rear assemblies to change the focal length of the entire system.

Abstract: The disclosed finder system includes, from front to rear, a first objective lens of negative power, an optical member having a half-mirror, an eyepiece of positive power and a viewfinder frame arranged near the eyepiece to be observed by the eyepiece with the aid of a reflection from the half-mirror. The finder system satisfies the condition 0.2<d/D<0.6 where D is the air separation between the first objective lens and the eyepiece lens and d is the air separation between the optical member and the eyepiece lens. Thus the first objective lens is exchangeable for a second objective lens of different power from that of the first objective lens to change the magnification of the finder system.

Abstract: A magnetic recording medium comprising a substrate, a thin magnetic metal film having spaced-apart columnar grains deposited on the substrate, and an organic polymer formed in the space between the columnar grains and integrated therewith. The medium is prepared by impregnating the spaces between the columnar grains with organic monomers or oligomers and polymerizing them in the spaces.

Abstract: An Albada finder is constructed of an objective lens, a reflection layer, a field-of-view defining frame, and an eyepiece arranged in sequence to provide a mirror image of the frame from the reflection layer to the eyepiece. An optical device of positive power is arranged outside an optical path of the finder. An information source with an information display plate and an illuminator for illuminating the display plate are arranged so that light from the display plate comes through the optical device into the eyepiece as an oblique beam. This shortens the distance from the reflection layer to the eyepiece while achieving a sharp information display.

Abstract: A magnetic recording medium is described, comprising a non-magnetic support having provided thereon a magnetic layer comprising ferromagnetic particles dispersed in a binder, said ferromagnetic particles having a BET specific surface area of 25 m.sup.2 /g or more, said binder comprising a modified polyurethane resin containing 0.1 meq/g or more of functional groups selected from carboxyl groups, hydroxyl groups, sulfonic acid groups, and epoxy groups, and containing at least three functional groups per molecule of the resin.

Abstract: As dichroic dyes for use in a liquid color display device, compounds of formula (I) ##STR1## such as 4'-octylphenyl perylene-3,9-dicarboxylate are provided. These compounds have various characteristic properties. For example, (1) they have a sufficient coloring ability in small amounts; (2) they have a high dichroic ratio and show a high contrast by application and non-application of voltage; (3) they have sufficient compatibility with liquid crystals; (4) they have excellent durability, are stable, and do not reduce the performance of a display device even in long-term use.

Abstract: An anthraquinonic dye of the formula ##STR1## is provided. When used as dichloric dyes in liquid crystalline color display elements, these dyes (1) have sufficient coloring ability in small amounts, (2) have a high dichloric ratio, (3) are fully soluble in liquid crystals, and (4) have excellent durability, are stable and do not degrade the performance of a display device upon long-term use.

Abstract: This invention provides a magnetic recording medium, in particular, magnetic recording tape whose coefficient of friction is decreased and running durability is improved without deteriorating the S/N property, which comprises a magnetic layer on one side of a support and a back layer on the other side thereof, the back layer containing a filler dispersed in a binder, characterized in that the binder consists essentially of a cellulose resin, a diolefin- or olefin-type synthetic rubber and a polyisocyanate.

Abstract: An undifferentiated symbiotic combination of alga and fungus cells, obtained directly from a lichen explant, are cultured in a media under appropriate conditions to produce aromatic lichenous substances and these substances are recovered.

Abstract: A display device in a view finder of a camera includes an illumination light source for illuminating the display portion and an illumination light leading body. The body has a reflecting surface and two permeable surfaces having such a refracting force such that the light emitting portion of the illumination light source is almost conjugate with the position of the pupil while observing the image in the view finder. The apparatus is arranged in such a manner that the illumination light beam is incident upon the one permeable surface of the illumination light leading body and goes out at the other permeable surface so as to illuminate the display portion. Accordingly, the display portion is observed together with the image in the view finder.