Abstract: An oscillator is connected with a DC power source for generating an oscillating output current. A plurality of capacitors are connected with the oscillator by way of diodes and are charged by the output current from the oscillator. The connecting point between each capacitor and its associated diode is connected via a switching circuit to an electromagnetic coil. For instance, one capacitor is connected with a coil for driving a leading shutter blind and another capacitor is connected with a coil for driving a trailing shutter blind.

Abstract: A thin permanent magnet sheet is sealed in a plastic blade. The magnet sheet is provided with perforations for binding the plastic material on one side of the magnet sheet with the plastic material on the other side thereof, thereby reinforcing the blade and facilitating the manufacture thereof. The magnet sheet is further provided on both sides thereof with projections of equal height to facilitate the molding of the plastic blade with the magnet sheet sealed therein at the middle of the thickness thereof.

Abstract: A leading blind and a trailing blind are made of opaque plastic sheet material. Each blind has a thin permanent magnet sealed within it along a plane approximately bisecting its thickness. Along the path of each blind is arranged at least one series of electromagnetic coils. Contactless magnetic or optical means is provided to detect the position of each blind and to sequentially energize the associated series of electromagnetic coils to cause the associated permanent magnet and blind to be driven in the direction in which the coils are sequentially energized in accordance with the principle of a linear motor.

Abstract: A series of thin electromagnetic print coils of rectangular shape are arranged in a line overlapped with each other in which each coil is slightly offset from the preceding coil, and are molded together with a plastic material to form a thin elongated coil group. The coil group is bent into the shape of rectangular or rounded "U" to guide therealong a movable member carrying therewith a permanent magnet. Preferably, longitudinally extending parts of windings of the coils are bent outward at right angles to the remaining part of the windings.

Abstract: A density-variable optical filter is mounted on a camera so that the density of the filter may be freely selected by manual operation independently of the aperture size of a diaphragm and the shutter speed. In a preferred embodiment, a rotatable ring for controlling the density of the density-variable filter graduated with a scale of one unit system is mounted to the lens barrel of the taking lens of the camera and an exposure meter which has a needle swingable in the field of view of a view finder graduated with a scale of the same unit system as that of the rotatable ring for controlling the filter density is provided to indicate the scene brightness.

Abstract: A shrinkable accordion shaped shutter blind is provided an end of which is fixed at one side of a film aperture and the other end of which is made free to move across the film aperture. The free end of the shutter blind is movable back and forth across the film aperture by a mechanical or electromagnetic operating device. In a preferred embodiment of the invention, a pair of the accordion shaped shutter blinds are provided to make a slit of exposure to expose a film behind the film aperture.

Abstract: An optical filter the density of which is variable is provided in the optical path of the taking lens. The density of the filter is controlled to effect optimum exposure with freely selected aperture size and the shutter speed by means of an exposure control circuit. The density of the filter is varied by moving a filter operating member which is driven by a filter driving means. The stroke of the filter operating member is controlled by means operated by electric pulses supplied by an electric circuit connected with a light measuring circuit including a photodetector to measure the scene brightness. The electric circuit for supplying the pulses for controlling the filter includes exposure factor input means and an arithmetic unit employing logic circuits.

Abstract: A spring drum including a coil spring for rotation about a shaft is provided with a cone shaped member located within a cylindrical drum. The cone shaped member is disposed in the drum coaxially with the drum and one end of the coil spring is fixed to the cone shaped member. The coil spring is shaped to have a conical form and provided around the cone shaped member. One end of the coil spring is fixed to the drum and the other end to the shaft, or vice versa.

Abstract: A thin electromagnetic coil sheet is sealed in a plastic blade. The coil sheet is composed of a plastic film substrate and a photo-etched coil deposited thereon. The coil sheet is sealed in the plastic blade at the middle of the thickness thereof.

Abstract: Gas pressure is used for driving such operating members in a camera as a mirror swing up lever, a diaphragm control lever and a shutter operating mechanism. A gas cylinder containing a liquefied gas is connected with a cylinder having a piston by way of a flow control valve. The piston is connected with an operating member in the camera. In a preferred embodiment of the invention, a pressure regulating valve is provided between the gas cylinder and a subtank for storing vaporized gas at a room temperature to effect accurate control of operating members by the gas having a constant pressure.

Abstract: In a motor driven camera including a motor which starts upon the first stage of depression of a shutter release button, a clutch mechanism is provided between the motor and a film wind-up member. A shutter releasing circuit is provided which includes a first switch which is closed upon the second stage of depression of the shutter release button, a second switch which is opened upon the completion of shutter release and a third switch which is opened in response to the start of operation of the film wind-up member. A change-over lever changes over the clutch mechanism from a condition in which the rotation of the motor is transmitted to the driving wheel connected with the film wind-up member to a condition in which the rotation of the motor is not transmitted to the drive wheel.

Abstract: An optical filter the density of which is variable is provided in the optical path of the taking lens. The density of the filter is controlled to effect optimum exposure with freely selected aperture size and the shutter speed by means of an exposure control circuit. The density of the filter is varied by moving a filter operating member. The filter operating member is controlled by the output of an electric circuit connected with a light measuring circuit including a photodetector to measure the scene brightness.

Abstract: An optical filter the density of which is variable is provided in the optical path of the taking lens. The density of the filter is controlled to effect optimum exposure with freely selected aperture size and the shutter speed by means of an exposure control circuit. The density of the filter is varied by moving a filter operating member which is driven by a filter driving means. The stroke of the filter operating member is controlled by means operated by electric pulses generated by an electric circuit connected with a light measuring circuit including a photodetector to measure the scene brightness.

Abstract: A leading blind and a trailing blind are made of rigid material such as metal sheet and each is provided with at least one permanent magnet. Along the path of the blinds are arranged electromagnetic coils. Each magnet mounted on the blind has a brush which is in slidable contact with the contacts connected with the electromagnetic coils. The magnet on the blind and the electromagnetic coils arranged in a line along the path of the blind constitute a linear motor to drive the blind. The coils are connected with an exposure control circuit and are energized to drive the blind. The leading blind is driven upon depression of a shutter release button and the trailing blind is driven when a time determined by the exposure control circuit has lapsed. In a preferred embodiment of the invention, the blind is divided into a driving blade and a follower blade to save the space occupied by the blind.

Abstract: An optical filter the density of which is variable is provided in the optical path of the taking lens. The density of the filter is controlled to effect optimum exposure with freely selected aperture size and the shutter speed by means of an exposure control circuit. The density of the filter is varied by moving a filter operating member which is driven by a filter driving means. The start and stop of the filter operating member is controlled by a start controlling electromagnet and a stop controlling electromagnet which are controlled by an electric circuit connected with a light measuring circuit including a photodetector to measure the scene brightness.

Abstract: Capacitors are connected in parallel with a power source. Each capacitor is connected in parallel with an electromagnetic coil by way of a switch. At least one but not all of said coils are connected in parallel with an RC time constant circuit so that the energization thereof may be delayed thereby. All switches are simultaneously closed and the coils are energized in the order determined by the time constants of the time constant circuits connected therewith. Between adjacent capacitors are connected diodes which prevent the capacitors connected with coils to be energized later from discharging through the coils to be energized earlier.