Automatic exposure apparatus for cameras

Claim 2

An automatic exposure apparatus for a camera, comprising: an opto/electric light transducer for producing an exposure signal; an amplifier having first and second inputs, and an output for connection to a controlled device, said transducer connected to said first input, a feedback circuit connected between said output and said second input and having a variable feedback signal whose value preceding the exposure is large compared with its value during the exposure, said feedback circuit comprising storage means for storing a feedback signal representative of the exposure signal preceding said exposure; means operable to make said exposure signal and said feedback signal effective at their respective inputs to said amplifier during an exposure; and a switch closed before an exposure and connected in parallel with said transducer and opened during an exposure.

Claim 3

An automatic exposure apparatus for a camera, comprising: an opto/electric light transducer for producing an exposure signal; an amplifier having first and second inputs, and an output for connection to a controlled device, said transducer connected to said first input, a feedback circuit connected between said output and said second input and having a variable feedback signal whose value preceding the exposure is large compared with its value durinG the exposure, said feedback circuit comprising storage means for storing a feedback signal representative of the exposure signal preceding an exposure; means operable to make said exposure signal and said feedback signal effective at their respective inputs to said amplifier during an exposure; said amplifier being an operational amplifier, wherein said first input is a non-inverting input and said second input is an inverting input, said feedback circuit comprising a normally closed switch operable to disconnect said output from said feedback circuit during an exposure; a first field effect transistor connecting said transducer to said non-inverting input; a second field effect transistor connecting said storage means to said inverting input; a phase reversing stage connecting said output to said non-inverting input via said first field effect transistor; and an integration capacitor connected between said phase reversing stage and said first field effect transistor.

Claim 4

An automatic exposure apparatus for a camera, comprising: an opto/electric light transducer for producing an exposure signal; an amplifier having first and second inputs, and an output for connection to a controlled device, said transducer connected to said first input, a feedback circuit connected between said output and said second input and having a variable feedback signal whose value preceding the exposure is large compared with its value durinG the exposure, said feedback circuit comprising storage means for storing a feedback signal representative of the exposure signal preceding an exposure; means operable to make said exposure signal and said feedback signal effective at their respective inputs to said amplifier during an exposure; said amplifier being an operational amplifier, wherein said first input is a non-inverting input and said second input is an inverting input, said feedback circuit comprising a normally closed switch operable to disconnect said output from said feedback circuit during an exposure; a first field effect transistor connecting said transducer to said non-inverting input; a second field effect transistor connecting said storage means to said inverting input; a phase reversing stage connecting said output to said non-inverting input via said first field effect transistor; and an integration capacitor connected between said phase reversing stage and said first field effect transistor.

Claim 5

Apparatus according to claim 2, wherein said phase reversing stage includes a bipolar transistor having a first electrode connected to said output and a second electrode connected to said capacitor.

Claim 6

Apparatus according to claim 3, comprising a measuring instrument connected to said output and another normally closed switch connected in the path between said output and said non-inverting input and opened at the initiation of an exposure.

Claim 7

Automatic exposure apparatus for a camera, comprising an opto/electric light transducer including a photo diode responsive to light to produce an exposure signal; an operational amplifier having a non-inverting input, an inverting input, and an output for connection to a controlled device; first and second field effect transistors connected to respective ones of said inputs, said photo diode connected to said first field effect transistor; first and second feedback circuits connected between said output and said field effect transistors, respectively; a first switch normally shunting said photo diode; a storage capacitor in said second feedbck circuit for storing a feedback signal representative of the last exposure; a second normally closed switch connecting said output to said storage capacitor; a phase reversing stage in said first feedback path to reverse the phase of the fed back output signal; and an integration capacitor connected in said first feedback path between said phase reversing stage and said first field effect transistor for integrating the phase reversed feedback signal, said switches operable to effect application of said exposure and feedback signals to said field effect transistors during an exposure.

Claim 8

Automatic exposure apparatus for a camera, comprising an opto/electric light transducer including a photo diode responsive to light to produce an exposure signal; an operational amplifier having a non-inverting input, an inverting input, and an output for connection to a controlled device; first and second field effect transistors connected to respective ones of said inputs, said photo diode connected to said first field effect transistor; first and second feedback circuits connected between said output and said field effect transistors, respectively; a first switch normally shunting said photo diode; a storage capacitor in said second feedbck circuit for storing a feedback signal representative of the last exposure; a second normally closed switch connecting said output to said storage capacitor; a phase reversing stage in said first feedback path to reverse the phase of the fed back output signal; and an integration capacitor connected in said first feedback path between said phase reversing stage and said first field effect transistor for integrating the phase reversed feedback signal, said switches operable to effect application of said exposure and feedback signals to said field effect transistors during an exposure.

Claim 9

Apparatus according to claim 5, comprising a light meter connected to said output and a third switch for opening said first feedback circuit during an exposure.