Memory circuit of an electric shutter

Claim 2

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to electric signal conversion means positioned behind said objective lens for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding electric signal having a value essentially linearly proportional to a logarithm of said value of light intensity; memory means for storing said electrical signal; switch means for coupling said memory means to said conversion means during intervals when the light passing through said objective lens is incident on said conversion means and for disconnecting said memory means from said conversion means when light passing through said objective lens is not incident on said conversion means; and control means coupled to said memory means to control the open time of said shutter in accordance with the electrical signal stored in said memory means.

Claim 3

In a camera, an exposure control arrangement as in claim 1, wherein said memory means includes a capacitor and said conversion means includes means producing a voltage essentially linearly proportional to a logarithm of the value of the intensity of the light passing through said objective lens.

Claim 4

In a camera, an exposure control arrangement as in claim 2, wherein said conversion means includes photoconductor means responsive to the light passing through said objective lens and diode means series connected to said photoconductor means, said series connected photoconductor means and diode means being connected across a source of operating potential.

Claim 5

In a camera, an exposure control arrangement according to claim 3, wherein said diode means includes a transistor having base, emitter and collector electrodes, said base and collector electrodes being connected together.

Claim 6

In a camera, an exposure control arrangement according to claim 3, wherein said conversion means includes first and second series connected photoconductor means, said first and second photoconductor means being arranged to receive said light passing through said objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor means, and a third resistance element connected to the junction of said series connected resistance elements.

Claim 7

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light responsive means for producing an output current related to the intensity of the light passing through said objective lens during Use of said camera; conversion means coupled to said light responsive means for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of light incident on said light responsive means; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said conversion means during intervals when light passing through said objective lens is incident on said light responsive means and for disconnecting said memory means from said conversion means when light passing through said objective lens is not incident on said light responsive means; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 8

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light responsive means for producing an output current related to the intensity of the light passing through said objective lens during Use of said camera; conversion means coupled to said light responsive means for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of light incident on said light responsive means; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said conversion means during intervals when light passing through said objective lens is incident on said light responsive means and for disconnecting said memory means from said conversion means when light passing through said objective lens is not incident on said light responsive means; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 9

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: photoconductor means for producing an output current related to the intensity of the light passing through said objective lens during use of said camera; a transistor for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of light incident on said photoconductor means, said transistor having base, emitter and collector electrodes, said base and collector electrodes being connected together; means connecting said photoconductor means and said transistor in series connection across a source of operating potential; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said transistor during intervals when light passing through said objective lens is incident on said photoconductor means and for disconnecting said capacitor memory means from said conversion means when light passing through said objective lens is incident on said photoconductor means; and control means coupled to said capacitor memory means for controlling the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 10

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: photoconductor means for producing an output current related to the intensity of the light passing through said objective lens during use of said camera; a transistor for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of light incident on said photoconductor means, said transistor having base, emitter and collector electrodes, said base and collector electrodes being connected together; means connecting said photoconductor means and said transistor in series connection across a source of operating potential; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said transistor during intervals when light passing through said objective lens is incident on said photoconductor means and for disconnecting said capacitor memory means from said conversion means when light passing through said objective lens is incident on said photoconductor means; and control means coupled to said capacitor memory means for controlling the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 11

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said intensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through sad objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a third resistance element connected to the junction of said series connected resistance elements; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said third resistor during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said memory means from said third resistor when light passing said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 12

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said intensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through sad objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a third resistance element connected to the junction of said series connected resistance elements; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said third resistor during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said memory means from said third resistor when light passing said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 13

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said iNtensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through said objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a potentiometer connected to the junction of said series connected resistance elements; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said potentiometer during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said capacitor memory means from said potentiometer when light passing through said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage on said capacitor memory means.

Claim 14

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said iNtensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through said objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a potentiometer connected to the junction of said series connected resistance elements; capacitor memory means for storing said voltage; switch means for coupling said capacitor memory means to said potentiometer during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said capacitor memory means from said potentiometer when light passing through said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage on said capacitor memory means.

Claim 15

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said intensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through said objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a third resistance element connected to the junction of said series connected resistance elements; amplifying circuit means connected to said junction for providing an output voltage proportional to said voltage, capacitor memory means for storing said output voltage; switch means for coupling said capacitor memory means to said amplifying means during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said capacitor memory means from said amplifying means when the light passing through said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 16

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: light intensity to voltage conversion means for converting essentially each value of the intensity of the light passing through said objective lens during use of said camera to a corresponding voltage which is essentially linearly proportional to a logarithm of the value of said intensity, said conversion means including a first photoconductor, a second photoconductor series connected to said first photoconductor, said first and second photoconductors being arranged to receive said light passing through said objective lens, first and second series connected resistance elements connected in parallel with said second photoconductor, and a third resistance element connected to the junction of said series connected resistance elements; amplifying circuit means connected to said junction for providing an output voltage proportional to said voltage, capacitor memory means for storing said output voltage; switch means for coupling said capacitor memory means to said amplifying means during intervals when light passing through said objective lens is incident on said first and second photoconductors and for disconnecting said capacitor memory means from said amplifying means when the light passing through said objective lens is not incident on said first and second photoconductors; and control means coupled to said capacitor memory means to control the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 17

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: a photoconductor for producing an output current related to the intensity of the light passing through said objective lens during use of said camera; a diode series connected with said photoconductor for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of the light incident on said photoconductor, said series connected diode and photoconductor being connected across a source of operating potential; capacitor memory means selectively coupled to the junction of said photoconductor and said diode for storing at least a portion of said voltage; and control means for controlling the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 18

In a camera having an objective lens and a shutter moveable between closed and open positions, an exposure control arrangement comprising: a photoconductor for producing an output current related to the intensity of the light passing through said objective lens during use of said camera; a diode series connected with said photoconductor for producing a voltage which is essentially linearly proportional to a logarithm of the value of the intensity of the light incident on said photoconductor, said series connected diode and photoconductor being connected across a source of operating potential; capacitor memory means selectively coupled to the junction of said photoconductor and said diode for storing at least a portion of said voltage; and control means for controlling the open time of said shutter in accordance with the stored voltage in said capacitor memory means.

Claim 19

In a camera, an exposure control arrangement as set forth in claim 11 further comprising: an amplifying stage coupling said junction to said capacitor memory means, said amplifying stage being in the configuration of an emitter follower.

Claim 20

In a camera, an exposure control arrangement as set forth in claim 12, wherein said amplifying stage comprises: a transistor having a control electrode and a potentiometer, having a tap, series connectEd across a source of operating potential, said control electrode of said transistor being coupled to said junction and the tap of said potentiometer being connected to said capacitor memory means.