Abstract: In an image forming apparatus for selectively reproducing positive and negative electrostatic latent images corresponding to an original image, there is provided a photosensitive medium having an insulating layer on its surface, a first charger capable of uniformly imparting charges to the surface of the photosensitive medium, a second charger capable of acting on the photosensitive medium after the action of the first charger, projection apparatus for projecting the original image to expose the photosensitive medium to the image, a third charger open with respect to the projection-exposure of the original image by the projection apparatus and capable of acting on the photosensitive medium simultaneously therewith, a uniform exposure lamp for imparting uniform exposure to the photosensitive medium, and control circuitry for controlling the operations of the second and third chargers and the uniform exposure lamp.

Abstract: A single lens reflex camera adjusted to a shutter preference exposure range in which responsive to the light sensor and preselected shutter speed, an Appex type computer derives an exposure value which is previously stored, and thereafter automatic adjustment of the diaphragm mechanism in accordance with the stored exposure value starts in substantial coincidence with the start of pivoting movement of the mirror from its viewing to non-viewing position which is followed by the operation of the shutter mechanism to thereby minimize the time interval between the time when the shutter button is depressed and the time at which the shutter is released from its cocked position.

Abstract: A prism positioned behind the objective rotates at a predetermined frequency. The pulsed light beam produced thereby is split into a first and second pulsed beam, each falling on a photoelectric transducer element. The first photoelectric transducer element is positioned at a distance from the objective which is less than the distance between the film plane and the objective plane by a predetermined distance. The second photoelectric transducer is positioned away from the objective by a distance exceeding the distance between the film plane and the objective plane by the same predetermined distance. The first and second electrical signals produced by the first and second photoelectric transducer are differentiated and stored. The so-stored signals are compared and a control signal for driving a motor in a first or second direction is furnished corresponding to the difference therebetween. The motor drives the objective either closer to or away from the film plane in response to the control signal.

Abstract: The start of the leading curtain or the trailing curtain of a focal plane shutter is controlled to obtain an accurate exposure time. A delay means is provided in the mechanism for releasing the leading curtain or in the mechanism for releasing the trailing curtain. The difference between the delay time of the start of the leading curtain and the delay time of the start of the trailing curtain is controlled to be equal to the constant time during which the leading curtain runs overlapping with the trailing curtain. In one embodiment, an inertia member is provided in the vicinity of the curtain release member to delay the movement of the curtain release member. In another embodiment, an electric delay circuit is provided to delay the start of the trailing curtain. In both embodiments, the time of delay of the start of the curtain can be controlled.

Abstract: A mechanism which can be utilized to drive a rotating sector disc type light shutter with a high degree of precision, so as to control light exposures that are made through a stationary aperture. Unlike the prior art, this inventive mechanism can be used to extend the exposure duration range almost indefinitely. In essence, this is accomplished with the inventive mechanism by stopping the motion of the sector disc shutter, with the open portion of the sector disc aligned with the stationary aperture, and then, after a preset elapsed interval, restarting the disc to close the aperture and terminate the exposure. Also unlike the prior art, this inventive mechanism obviates the need for critical timing.