Abstract: According to an optical system of an optical pickup of the present invention, beam is split into two portions by a light refracting member which is disposed between a condenser lens and a light receiving element, a portion of beam entering into the light refracting member is utilized for detecting tracking errors, and the remaining portion of beam which is not permitted to enter into the light refracting member is utilized for detecting focussing errors by a knife edge test. With the above-mentioned constitution of the optical system, a tracking error composition is prevented from interferring with the focussing error detection and, at the same time, both the tracking errors and focussing errors can be detected by one light receiving element. Thus, the number of component parts can be reduced and the optical system itself can be made compact.

Abstract: An electronically controlled camera is provided which has a back cover switch adapted to be turned ON/OFF according to the opening/closing position of a back cover; a back cover switch data detecting device for detecting switch data relating to the back cover switch, at a predetermined cycle, and for outputting such data; an erasable programmable memory for memorizing the switch data output from the back cover switch data detecting device; and a control device for comparing the switch data from the latest cycle output from the back cover switch data detecting device with the switch data from the preceding cycle read from the memory, and for controlling a film advance motor, a display system and the memory.

Abstract: A display device in a camera with a zoom lens, for providing a visual indication of the setting of the zoom lens. It includes a zoom encoder (10) for detecting the zoom lens setting, a liquid crystal display (8) having a plurality of display segments (S1-S15) disposed in an arcuate pattern, and drive circuits (24, 25) for driving the display segments. A micro-computer (20) controls the drive circuits, based on the zoom setting as detected by the zoom encoder (10), such that the state of each of the display segments can be changed by the drive circuits in response to a change in the angle of view of the zoom lens.The display device can provide an intuitively perceivable visual indication with the arcuate array of display segments (S1-S15).

Abstract: A reference position-detecting device for use with a photoelectric, incremental encoder which produces a sinusoidal signal in response to the movement of an index scale relative to a main scale. A pattern comprising bright portions and dark portions alternately arranged is formed on the main scale. A similar pattern is formed on the index scale. The device comprises a random pattern formed at some location of the main scale, a similar random pattern formed at some location of the index scale, optical devices for producing a signal indicative of a reference position, a first pulse generator for producing pulses in response to the signal above, second and third pulse generators for producing two kinds of pulses that are 90.degree.

Abstract: A plastic lens which has high hardness and excellent scratch resistance and can form a transparent and uniform reflection preventing film through vacuum deposition, is produced by mixing(a) diethylene glycol bis(allyl carbonate) with(b) at least one of organic peroxides having a decomposition temperature at selected half-life value for ten hours of not higher than 80.degree. C. and(c) at least one of specifically limited peroxycarbonates having a radical copolymerizability to the diethylene glycol bis(allyl carbonate) (a), as a polymerization initiator, and polymerizing and casting the resulting mixture in a desired lens-forming mold.

Abstract: There is disclosed herein several embodiments of a six-element telephoto lens system comprising, in order from an object, a first positive lens, a second negative lens, third and fourth positive-meniscus lenses having convex surfaces directed toward the object, a fifth negative lens, and a sixth positive lens, said lens system being arranged to meet the following conditions(1) 0.4f<f.sub.1, 2, 3, <0.75f(2) 0.35f<f.sub.1, 2, 3, 4, <0.6f(3) 0.65f<f.sub.1 <0.8f(4) d.sub.2 <0.02f(5) 0.2f<.vertline.f.sub.5, 6 .vertline.<0.45f, f.sub.5, 6 <0(6) 0.05<n5-n6wheref is the focal length of the overall lens system,f.sub.1, 2, 3 is the combined focal length of the first through third lenses,f.sub.1, 2, 3, 4, is the combined focal length of the first through fourth lenses,f.sub.1 is the focal length of the first lens,d.sub.2 is the distance between the first and second lenses,f.sub.5, 6, is the combined focal length of the fifth and sixth lenses,n.sub.

Abstract: A method and device for use in detecting a precise focussing point, which comprises the steps of: placing a photoelectric element on an optical path or optical axis of a lens of a camera; converting the information of the precise focussing point for a photographic object into a frequency variation of an A. C. signal; feeding said signal having varying frequency to a highly sensitive frequency detector such as a resonance circuit, a tuned amplifier, or frequency-amplitude convertor having acute frequency characteristics; and detecting the precise focussing point with high sensitivity by means of the output thus obtained; whereby the aforesaid functions may be satisfactorily performed, irrespective of the variation in the luminance of the object and whereby the focus of the lens may be brought into precise conformity to the predetermined plane (i.e., the position corresponding to a film).

Abstract: An eyeglass device includes a primary and an auxiliary spectacle frames for supporting lenses. The primary spectacle frame includes two legs pivotally coupled to two side extensions and includes two magnetic members secured in the rear and side portions. The auxiliary spectacle frame includes two legs engaged on the primary spectacle frame and each having a magnetic member for engaging with the magnetic members of the primary spectacle frame so as to secure the spectacle frames together and so as to prevent the auxiliary spectacle frame from moving downward relative to the primary spectacle frame.