Polaroid Corporation

David L Farrington

Norman D Staller

George D Whiteside

Philip R Norris

Jon E Van Tassell

A Brian Holland

Jane L Riemenschneider

Thomas A Lumenello

A compact dual imaging camera is disclosed wherein conventional and self-developing photographic films are generally simultaneously exposed from a common scene through separate taking apertures.

Dual exposure photographic apparatus and method

There is disclosed a photographic system incorporating a photographic apparatus of the type including an exposure control system which senses and evaluates ambient and infrared spectral energy for controlling camera functions; as well as an accessory for use in combination therewith which compensates for attenuation of infrared energy underwater which infrared energy would otherwise be used in controlling the camera functions. Provision is made for a supplemental source of infrared energy that is directed to such system for a time period and in an amount based upon an evaluation of reflected visible spectral energy from the scene.

Method and apparatus for controlling exposure

A simplifed open loop focus control system for a fixed focus lens camera that positions a supplemental lens into the optical path of a fixed focus lens, for relatively remote subjects, in response to a signal representative of subject reflectivity. Inserting such a lens in this manner substantially reduces focus control system complexity while at the same time minimizing the frequency of supplemental lens movement for most exposures which are typically of subjects that are relatively close to the fixed focus lens camera.

Supplemental lens positioning system for a fixed focus lens camera

An exposure control system for a photographic camera employing a scanning type shutter that includes a pair of cooperating shutter blade elements automatically compensates for exposure altering variations in shutter blade element speed that may occur from one exposure interval to another. The exposure control system incudes an encoder to provide information on the actual position of the shutter blade elements as a function of time during an exposure cycle. The encoder generates a series of pulses representative of relative blade element position as the blades are moved during the exposure cycle. The time between these pulses is measured and directly converted into a signal representative of shutter blade element speed or velocity. This shutter blade speed signal is then employed to alter the duration of an exposure interval to compensate for any shutter blade element speed variations.

Method and apparatus for compensating for shutter speed variations

An exposure control system for a camera having a scanning type shutter mechanism for forming a range of aperture areas through which a photographic image is formed includes a stepper motor and a regulator or open loop control system therefor, to actuate the shutter mechanism between its open and closed positions in correspondence with a predetermined set of aperture area defining curves selected in accordance with sensed scene brightness and subject reflectivity levels. The stepper motor is operated at a relatively low rate of speed in order to avoid shutter blade mechanism overshoot and to achieve substantially the same shutter mechanism positioning accuracy as that achieved with a closed loop control system. Employing a stepper motor together with an open loop control system for scanning shutter mechanism actuation in the above member, results in a simplified exposure control system that is both compact and relatively inexpensive.

Open-loop stepper motor controlled shutter

An exposure control circuit for a photographic apparatus that senses visible and infrared scene light with separate light sensing photodiodes employs a single integrator and a separate capacitor for the storage of each scene light integration to sequentially integrate the light levels sensed by such diodes in controlling the amount of image-carrying scene light admitted to the film plane of the apparatus through a scanning aperture. By utilizing a single integrator and separate storage capacitors for each light integration for such light control, a considerable amount of valuable space can be saved in, for example, an integrated circuit over a system where multiple integrators are employed for such purposes.

Single integrator system with dual photocells

An image of a subject in a scene formed by a fixed focus lens through a scanning aperture of an electronic flash camera, particularly that of a subject located closer to the lens than the near distance of its lens normal depth of field, has its clarity or sharpness substantially improved by firing the electronic flash during exposure at the smallest possible aperture for optimum subject image sharpness and overall scene exposure. The appropriate aperture to produce such an image is a function of ambient scene brightness and of the IR light from the electronic flash being reflected from a subject within the scene which are determined prior to and/or at the early stages of an exposure interval.

Growing community of inventors

Boxborough, MA, United States of America

David L Farrington