US 4,230,400 AGranted

Photographic camera with exposure-control and focussing means

AssigneeAgfa-Gevaert

InventorsRichard Wick, Otto Stemme, Peter Lermann, Karl Wagner, Kurt Borowski, Istvan Cocron, Gunter Fauth

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Abstract

A focussing system emits an infrared light beam towards the subject, the reflected beam passing through an infrared filter and being projected by a spot optics as a small spot onto a pair of photosensitive elements. The spot optics shifts in a plane normal to the camera's optical axis in dependence upon rotation of the camera's focussing ring, to vary the distribution of the reflected beam onto the two elements, the distribution being equal between them when the state of focus is correct. A circuit derives, from the output signals of the two photosensitive elements, a state-of-focus signal used to automatically focus or else to indicate to the user the direction in which he should manually adjust focus. When focussing is finished, the photosensitive elements are disconnected from the focussing circuitry and connected to the camera's exposure-control circuitry, to thereby serve a dual function. The infrared filter moves out of the light path of the photosensitive elements. The spot optics is moved out of the light path of the photosensitive elements, so that for exposure control a larger light field can be established, or else an auxiliary optics moves into the light path to enlarge the light field in that manner.

Claims17

Dependent claims

In a photographic camera, in combination, electronic exposure-control means having a light-dependent-signal input and operative for controlling exposure in dependence upon a light-dependent signal applied thereto;

state-of-focus evaluating means comprising a photosensitive detector arrangement producing light-dependent-signals, and including at least one pair of photosensitive elements, and including an emitter emitting towards the subject to be photographed a beam of radiation having a predetermined frequency range within the frequency spectrum to which the photosensitive detector arrangement can respond, means controlling the incidence of light on the photosensitive detector arrangement in dependence upon changes in the camera's state of focus, including means for controlling, in dependence upon changes in the camera's state of focus, the relarive locations of the photosensitive detector arrangement, on the one hand, and of said beam of radiation as reflected back from the subject to be photographed, on the other hand, the means controlling the relative locations of the photosensitive detector and beam of radiation comprising means controlling the distribution of the reflected-back beam of radiation as between the two elements of the photosensitive-element pair, means receiving the light-dependent signals produced by the detector arrangement and deriving therefrom a stat-of-focus signal indicating the camera's state of focus, including subtracting means receiving and subtracting from each other the light-dependent signals produced by the two elements of the photosensitive-element pair, and supressing means operative for suppressing the effect of radiation not originating from said emitter upon the light-dependent signals produced by the photosensitive elements, including an optical filter located in front of the photosensitive elements and operative for transmitting thereto substantially only radiation of frequency within said predetermined frequency range, and means moving the optical filter out of the light path of the photosensitive elements during exposures controlled by the exposure-control means;
and connecting means connecting the photosensitive detector arrangement of the state-of-focus evaluating means to the light-dependent-signal input of the exposure-control means for transmitting light-dependent signals to the latter from the former, so that the photosensitive detector arrangement be shared by both the exposure-control means and the state-of-focus evaluating means.

state-of-focus evaluating means comprising a photosensitive detector arrangement producing light-dependent-signals and including at least one pair of photosensitive elements, and an emitter emitting towards the subject to be photographed a beam of radiation having a predetermined frequency range within the frequency spectrum to which the photosensitive detector arrangement can respond, means controlling the incidence of light on the photosensitive detector arrangement in dependence upon changes in the camera's state of focus, including means for controlling, in dependence upon changes in the camera's state of focus, the relative locations of the photosensitive detector arrangement, on the one hand, and of said beam of radiation as reflected back from the subject to be photographed, on the other hand, the means controlling the relative locations of the photosensitive detector and beam of radiation comprising means controlling the distribution of the reflectedback beam of radiation as between the two elements of the photosensitive-element pair, means receiving the light-dependent signals produced by the detector arrangement and deriving therefrom a state-of-focus signal indicating the camera's state of focus, including subtracting means receiving and subtracting from each other the light-dependent signals produced by the two elements of the photosensitive-element pair, and suppressing means operative for suppressing the effect of radiation not originating from said emitter upon the light-dependent signals produced by the photosensitive elements, including an optical filter located in front of the photosensitive elements and operative for transmitting thereto substantially only radiation of frequency within said predetermined frequency range and a spot optics located in front of the photosensitive elements and operative for projecting onto them a small spot of light having a small field, and means operative for enlarging the field of light incident on the photosensitive elements during exposures controlled by the exposure-control means;
and connecting means connecting the photosensitive detector arrangement of the state-of-focus evaluating means to the light-dependent-signal input of the exposure-control means for transmitting light-dependent signals to the latter from the former, so that the photosensitive detector arrangement be shared by both the exposure-control means and the state-of-focus evaluating means.

Dependencies are inferred from the claim text.