Oscillation systems for control of camera shutters

Claim 2

In a camera having an electronically controlled shutter, oscillation means for providing a series of pulse signals whose frequency is a function of light intensity at an object to be photographed, shutter-opening circuit means electrically connected with said oscillation means for opening the shutter in response to one of said pulses selected by a shutter-release operation, exposure circuit means electrically connected with said shutter-opening circuit means for responding to said one pulse for converting preset exposure factors into a time duration starting with said one pulse and for providing a control signal after the elapse of said time duration, and shutter-closing circuit means electrically connected to said exposure circuit means for receiving said control signal and in cooperation therewith closing the shutter.

Claim 3

The combination of claim 1 anad wherein a photosensitive means for receiving light from the object to be photographed and for converting said light into a corresponding electrical quantity is electrically connected with said oscillation means for controlling said oscillation means.

Claim 4

The combination of claim 2 and wherein a memory circuit means is electrically connected between said photosensitive means and said oscillation means for storing the electrical quantity, and wherein the period of the series of pulse signals is determined by the stored electrical quantity.

Claim 5

The combination of claim 3 and wherein a normally closed switch means is connected between said photosensitive means and said memory circuit means for assuming an open position immediately prior to opening of the shutter.

Claim 6

The combination of claim 2 and wherein a logarithmic compression means is electrically connected with said photosensitive means for storing said electrical quantity in a logarithmically compressed form, and logarithmic expansion means electrically connected between said loGarithmic compression means and said oscillation means for transmitting a logarithmically expanded signal to said oscillation means.

Claim 7

The combination of claim 5 and wherein said logarithmic compression means includes diode means and wherein said logarithmic expansion means includes field effect transistor means.

Claim 8

The combination of claim 1 and wherein said preset exposure factors are controlled according to said light intensity at the object to be photographed.

Claim 9

The combination of claim 1 and wherein said shutter-closing circuit means comprises normally reversed biased diode means for receiving said control signal and becoming forward biased in response thereto, thyristor means having a gate coupled to said diode means for receiving an input therefrom, and trailing shutter curtain switch means in series with said thyristor means for closing the shutter when said thyristor means conducts.

Claim 10

The combination of claim 1 and wherein said shutter-opening circuit means comprises thyristor means having a gate coupled to said oscillator means and leading shutter curtain switch means connected in series with said thyristor means for opening the shutter when said thyristor means conducts.

Claim 11

The combination of claim 1 and wherein a switch means is serially connected between said oscillator means and said shutter-opening circuit means for effecting said release operation.

Claim 12

The combination of claim 2 and wherein said shutter-closing circuit means is electrically connected to said oscillator means for receiving said series of pulses and for closing the shutter in response to the next occurring pulse following the occurrence of said control signal.

Claim 13

The combination of claim 11 and wherein said photosensitive means is situated internally of the camera to receive light passing through a camera objective and wherein a storage means is electrically connected to said photosensitive means for receiving the electrical quantity from said photosensitive means, for storing it as a voltage proportional to said electrical quantity and for applying it to said oscillator means for controlling the frequency of said series of pulses.

Claim 14

The combination of claim 12 and wherein said preset exposure factors are controlled according to said stored voltage.

Claim 15

The combination of claim 12 and wherein a logarithmic compression means is electrically connected with said photosensitive means for storing the electrical quantity from said photosensitive means in logarithmic compressed form, first logarithmic expansion means connected between said logarithmic compression means and said oscillation means for receiving said stored electrical quantity and for providing a logarithmically expanded signal which is applied to said oscillation means, and second logarithmic expansion means connected between said logarithmic compression means and said exposure control means for transmitting a logarithmically expanded signal to said exposure circuit means.

Claim 16

The combination of claim 10 and wherein said exposure circuit means comprises first transistor means, variable resistor means preset in accordance with exposure factors, means responsive to the light intensity at the object to be photographed, said last-mentioned means and said variable resistor means being connected to said first transistor means to control the internal resistance thereof, capacitor means connected in series with said first transistor means, and signal circuit means connected to a junction between said first transistor means and said capacitor means for providing a control signal after a time delay determined by the capacitance of said capacitor means and the internal resistance of said first transistor means.

Claim 17

The combination of claim 11 and further including oscillation termination means connected to said shutter-closing circuit means, said exposure circuit means and said oscillation means for terminating said series of pulses from said oscillation means during the time duration determined by said expoSure circuit means.

Claim 18

The combination of claim 16 and wherein said exposure circuit means includes capacitor means adapted to be charged prior to said release operation, first transistor means connected in series with said capacitor means and having an internal impedence preset in accordance with exposure factors and wherein said termination means comprises second transistor means connected to said oscillation means for short circuiting the same when in a conductive state, Schmitt trigger circuit means having an input connected to said first transistor means and an output connected to said second transistor means so that when said capacitor means discharges through said first transistor in response to said one pulse, said Schmitt trigger changes state to thereby cause said second transistor to conduct thereby terminating further oscillation pulses, and when said capacitor means has discharged said Schmitt trigger circuit means returns to its original state thereby causing said second transistor means to stop conducting thereby again commencing operation of the oscillation means.

Claim 19

The combination of claim 16 and wherein said exposure circuit comprises capacitor means adapted to be charged prior to said release operation, pulse means coupled to said capacitor means for producing a negative pulse in response to the discharge of said capacitor means, transistor means for short circuiting when in a conductive state said oscillation means, multivibrator circuit means having an input connected to respond to said pulse means and an output connected to said transistor means for causing, so when said capacitor means discharges, said transistor means to conduct thereby short circuiting said oscillation means and for returning, when said capacitor has completed discharge, to its original state thereby causing said transistor means to stop conducting and said oscillation means again to commence producing said oscillation pulses.

Claim 20

The combination of claim 1 and wherein said exposure circuit means comprises a plurality of cascaded flip-flop means, and selecting switch means having a plurality of contacts capable of being preset with a predetermined number representative of said exposure factors, said selecting switch means being electrically connected between said shutter-closing circuit means and said cascaded flip-flop means with said contacts respectively connected to outputs of said flip-flop means whereby said control signal is produced when the flip-flop means corresponding to the number selected on the selecting switch means produces an output pulse, and wherein said cascaded flip-flop means receive said series of pulse signals from said oscillation means.

Claim 21

The combination of claim 19 and wherein one of the contacts of said selecting switch means is electrically connected to said oscillation means to directly receive said series of pulse signals.

Claim 22

The combination of claim 19 and wherein said shutter-closing circuit means is connected to said oscillator means for causing the next occurring pulse following the occurrence of said control signal to close the shutter.

Claim 23

The combination of claim 19 and wherein said control signal causes said shutter-closing circuit means to close the shutter.

Claim 24

The combination of claim 1 and wherein said exposure circuit means comprises voltage producing means for receiving said series of pulse signals and for producing in response to each of said pulse signals a step voltage the amplitude of which is a function of said exposure factors, and storing means connected to said voltage producing means for cumulatively storing said step voltage and for providing a control signal when said cumulatively stored step voltage reaches a predetermined value.

Claim 25

The combination of claim 23 and wherein said shutter-closing circuit means is connected to said oscillator means for receiving said series of pulses and for closing the shutter in response to the next occurring pulse following the occurrence of said control signal.

Claim 26

The combination of claim 23 and wherein said storage means comprises first capacitor means, first diode means having a series connection therewith, second diode means oppositely poled to said first diode means and connected between the series connection of said first capacitor means, and said first diode means and between a commmon terminal, and second capacitor means connected between the other side of said first diode means and said common terminal, said second capacitor means retaining the cumulatively stored step voltage.

Claim 27

The combination of claim 25 and further comprising feedback compensation means connected to said second capacitor means for reducing the error caused by cumulative electric charge on said second capacitor means.

Claim 28

The combination of claim 23 and wherein said exposure circuit means further comprises means responsive to the light intensity of the object being photographed, variable resistor means preset in accordance with the exposure factors, and transistor means connected to said variable resistor means for having an internal resistance controlled by said variable resistance means and said means responsive to light intensity, said transistor means being coupled to said voltage producing means to control the amplitude of the step voltage.