Abstract An automatic diaphragm adjustment device for a photographic camera in which a photoconductive cell is arranged in the input circuit of a Wheatstone bridge and is illuminated by light coming from the subject being photographed and passing through an adjustable diaphragm arranged in front of the photoconductive cell. The diaphragm is operatively connected with the adjustable diaphragm of the camera objective and with an electric motor. A transistor amplifier having at least two transistors is arranged in the diagonal of the Wheatstone bridge and controls the electric motor rotating it in one or the other direction as the case may be until the bridge is balanced. One of the transistors is bridged by a conductor including a manually operable switch, so that when the switch is closed the diaphragm is closed by the electric motor.
Automatic diaphragm adjustment device for a photographic camera, comprising a photoconductive cell, an adjustable diaphragm in front of the same for controlling the illumination energizing said cell, an adjustable camera objective diaphragm, an electric motor operatively connected with said two diaphragms, means forming a bridge circuit having an input circuit in which said photoconductive cell is arranged, at least two complementary transistors of the types PNP and NPN and two serially arranged voltage supply sources forming a transistor amplifier which is arranged in one of the diagonals of said bridge circuit for controlling the operation of said motor, and a disconnectable conductor arranged across the emitter-collector path of to one of said transistors for causing a closing of said diaphragm when said conductor is closed so as to bridge said transistor.
Claim 2
Dependent Claim
131 words
Automatic diaphragm adjustment device for a photographic camera, comprising a photoconductive cell, an adjustable diaphragm in front of the same for controlling the illumination energizing said cell, an adjustable camera objective diaphragm, an electric motor operatively connected with said two diaphragms, means forming a bridge circuit having an input circuit in which said photoconductive cell is arranged, at least two complementary transistors of the types PNP and NPN and two serially arranged voltage supply sources forming a transistor amplifier which is arranged in one of the diagonals of said bridge circuit for controlling the operation of said motor, and a disconnectable conductor arranged across the emitter-collector path of to one of said transistors for causing a closing of said diaphragm when said conductor is closed so as to bridge said transistor.
Claim 3
Dependent Claim
23 words
A device according to claim 1, in which said disconnectable conductor is connected with the emitter and the collector of said one transistor.
Claim 4
Dependent Claim
30 words
A device according to claim 1, including a switch in said disconnectable conductor and a manually operable switch key on the camera casing for controlling the operation of said switch.
Claim 5
Dependent Claim
50 words
A device according to claim 1, including a switch in said disconnectable conductor and a manually operable switch key on the camera casing for controlling the operation of said switch, said manually operable switch key being so constructed that upon release of the same it causes said switch to open.