Electronic shutter control device

Claim 2

In a camera having an electronically controlled shutter, an exposure control arrangement comprising; a. first conversion means for converting the value of the intensity of the light of the object to be photographed into a first voltage having a value proportional to a logarithm of the value of the light intensity; b. a pulse generator; c. a pulse counter connected to said pulse generator, said pulse counter counting the pulses from the pulse generator and producing a first current proportional to the counted pulses; d. second conversion means connected to the pulse counter for converting said first current flowing from the pulse counter into a second voltage proportional to the first current; e. comparison means connected to the first and second conversion means, said comparison means comparing the first voltage of said first conversion means with the second voltage of said second conversion means and producing a signal when the difference between the two voltages reaches a predetermined value; f. means coupling said pulse generator to said pulse counter and connected to said comparison means for preventing transmission of the pulses from said pulse generator to said pulse counter when said signal from said comparison means is applied to the coupling means, whereby the counter pulses are memorized in said pulse counter; and g. control means for controlling the shutter speed in response to the number of the pulses memorized in said pulse counter.

Claim 3

In a camera having an electronically controlled shutter, an exposure control arrangement comprising; a. first conversion means for converting the value of the intensity of the light of the object to be photographed into a first voltage having a value proportional to a logarithm of the value of the light intensity; b. a pulse generator; c. a pulse counter connected to said pulse generator, said pulse counter counting the pulses from the pulse generator and producing a first current proportional to the counted pulses; d. second conversion means connected to the pulse counter for converting said first current flowing from the pulse counter into a second voltage proportional to the first current; e. comparison means connected to the first and second conversion means, said comparison means comparing the first voltage of said first conversion means with the second voltage of said second conversion means and producing a signal when the difference between the two voltages reaches a predetermined value; f. means coupling said pulse generator to said pulse counter and connected to said comparison means for preventing transmission of the pulses from said pulse generator to said pulse counter when said signal from said comparison means is applied to the coupling means, whereby the counter pulses are memorized in said pulse counter; and g. control means for controlling the shutter speed in response to the number of the pulses memorized in said pulse counter.

Claim 4

In a camera having an electronically controlled shutter, an exposure control arrangement comprising; a. first conversion means for converting the value of the intensity of the light of the object to be photographed into a first voltage having a value proportional to a logarithm of the value of the light intensity; b. a pulse generator; c. a pulse counter connected to said pulse generator, said pulse counter counting the pulses from the pulse generator and producing a first current proportional to the counted pulses; d. second conversion means connected to the pulse counter for converting said first current flowing from the pulse counter into a second voltage proportional to the first current; e. comparison means connected to the first and second conversion means, said comparison means comparing the first voltage of said first conversion means with the second voltage of said second conversion means and producing a signal when the difference between the two voltages reaches a predetermined value; f. means coupling said pulse generator to said pulse counter and connected to said comparison means for preventing transmission of the pulses from said pulse generator to said pulse counter when said signal from said comparison means is applied to the coupling means, whereby the counter pulses are memorized in said pulse counter; and g. control means for controlling the shutter speed in response to the number of the pulses memorized in said pulse counter.

Claim 5

The exposure control arrangement as defined in claim 1 wherein said control means includes a. integrating circuit means having a capacitor and being coupled to said second conversion means to produce a second current proportional to an exponential function of the second voltage and to charge said capacitor with the second current upon the beginning of the opening movement of the shutter; and b. shutter closing means connected to said integrating circuit means for closing the shutter when the voltage across said capacitor reaches a predetermined value.

Claim 6

The exposure control arrangement as defined in claim 1, further comprising means connected to said pulse counter for regulating said first current correspondingly to variation in the film sensitivity and the objective lens aperture opening of the camera while said comparison means compares the first voltage with the second voltage.

Claim 7

The exposure control arrangement as defined in claim 1 further comprising means for regulating said first current correspondingly to variation in the film sensitivity and the objective lens aperture opening of the camera; and switching means for connecting said regulating means to said pulse counter while the comparison means compares the first voltage with the second voltage and disconnecting said regulating means from said pulse counter after the memorization of the counted pulses in the pulse counter.

Claim 8

The exposure control arrangement as defined in claim 4 wherein one end of said switching means is connected to the regulating means and the other end of the said switching means is connected to the junction between said second conversion means and said pulse counter.

Claim 9

The exposure control arrangement as define in claim 1 wherein the pulse counter is a binary counter.

Claim 10

The exposure control arrangement as defined in claim 1, further comprising indicator means connected to the pulse counter for indicating shutter speed corresponding to the pulses memorized in the pulse counter.

Claim 11

In a camera having an electronically controlled shutter, an exposure control arrangement comprising: a. a photoelectric element adapted to receive the light from the object to be photographed; b. a logarithm conversion means whose one end is connected to said photoelectric element, said logarithm conversion means converting the current from the photoelectric element into a voltage having a value proportional to a logarithm of the value of the light intensity; c. a pulse generator; d. a pulse counter connected to said pulse generator for counting the pulses from the pulse generator, said pulse counter producing a current proportional to the counted pulses; e. means connected between the pulse generator and the pulse counter for selectively permitting transmission of the pulses from the pulse generator to the pulse counter and preventing said transmission; f. second conversion means whose one end is connected to the pulse counter for receiving the current produced from the pulse counter and the other end is connected to the other end of said dogarithm conversion means, said second conversion means converting the current from the pulse counter into a voltage proportional to the current from the counter; g. comparison means for comparing the voltage of the logarithm conversion means with the voltage of the second conversion means, said comparison means including first and second operational amplifiers, said first operational amplifier having an inverting input terminal connected to the junction between the pulse counter and the second conversion means, a grounded non-inverting input terminal, and an output terminal connected to the junction between the logarithm conversion means and the second conversion means, said second operational amplifier having an inverting input terminal connected to the one end of the logarithm conversion means, a grounded non-inverting input terminal, and an output terminal connected to the selectively preventing means, said comparison means producing a signal at the output terminal of the second operational amplifier to cause said means connected between the pulse generator and the pulse counter to prevent said transmission of the pulses when the difference between said two voltages reaches a predetermined value, whereby the counted pulses are memorized in the pulse counter; h. first switching means for connecting the photoelectric element to the junction between the inverting input terminal of the second operational amplifier and the one end of the logarithm conversion means while the comparison means compares the voltage of the logarithm conversion means with the voltage of the second conversion means and disconnecting the photoelectric element from the junction between the second amplifier and the logarithm conversion means after memorization of the counted pulses in the pulse counter; i. capacitor means; j. second switching means for connecting the capacitor means between the output terminal of the second amplifier and the inverting input terminal of the second amplifier after the first switching means disconnects the photoelectric element from the junction between the second amplifier and the logarithm conversion means, said capacitor means being charged with the current flowing through the logarithm conversion means from the output terminal of the second amplifier when the shutter is opened; and k. shutter closing means for closing the shutter when the voltage across the capacitor reaches a predetermined value.

Claim 12

In a camera having an electronically controlled shutter, an exposure control arrangement comprising: a. a photoelectric element adapted to receive the light from the object to be photographed; b. a logarithm conversion means whose one end is connected to said photoelectric element, said logarithm conversion means converting the current from the photoelectric element into a voltage having a value proportional to a logarithm of the value of the light intensity; c. a pulse generator; d. a pulse counter connected to said pulse generator for counting the pulses from the pulse generator, said pulse counter producing a current proportional to the counted pulses; e. means connected between the pulse generator and the pulse counter for selectively permitting transmission of the pulses from the pulse generator to the pulse counter and preventing said transmission; f. second conversion means whose one end is connected to the pulse counter for receiving the current produced from the pulse counter and the other end is connected to the other end of said dogarithm conversion means, said second conversion means converting the current from the pulse counter into a voltage proportional to the current from the counter; g. comparison means for comparing the voltage of the logarithm conversion means with the voltage of the second conversion means, said comparison means including first and second operational amplifiers, said first operational amplifier having an inverting input terminal connected to the junction between the pulse counter and the second conversion means, a grounded non-inverting input terminal, and an output terminal connected to the junction between the logarithm conversion means and the second conversion means, said second operational amplifier having an inverting input terminal connected to the one end of the logarithm conversion means, a grounded non-inverting input terminal, and an output terminal connected to the selectively preventing means, said comparison means producing a signal at the output terminal of the second operational amplifier to cause said means connected between the pulse generator and the pulse counter to prevent said transmission of the pulses when the difference between said two voltages reaches a predetermined value, whereby the counted pulses are memorized in the pulse counter; h. first switching means for connecting the photoelectric element to the junction between the inverting input terminal of the second operational amplifier and the one end of the logarithm conversion means while the comparison means compares the voltage of the logarithm conversion means with the voltage of the second conversion means and disconnecting the photoelectric element from the junction between the second amplifier and the logarithm conversion means after memorization of the counted pulses in the pulse counter; i. capacitor means; j. second switching means for connecting the capacitor means between the output terminal of the second amplifier and the inverting input terminal of the second amplifier after the first switching means disconnects the photoelectric element from the junction between the second amplifier and the logarithm conversion means, said capacitor means being charged with the current flowing through the logarithm conversion means from the output terminal of the second amplifier when the shutter is opened; and k. shutter closing means for closing the shutter when the voltage across the capacitor reaches a predetermined value.

Claim 13

The exposure control arrangement as defined in claim 8 wherein the capacitor means includes third switching means for short-circuiting said capacitor while the third switching means is closed and for charging said capacitor while the third switching means is opened, said third switching means being opened in response to the opening movement of the shutter.