Camera with electrical shutter

Claim 2

A camera with an electrical shutter adapted to be used with an electronic flash unit including a flash discharge tube; said camera comprising: a photometric circuit including a light receiving element which adapted to effect through-the-lens photometry; a shutter; an electrical shutter control circuit which is responsive to an output of the photometric circuit for normally closing said shutter; auxiliary shutter closing means for receiving a first electrical signal supplied by the electronic flash unit in response to occurrence of the flashlight illumination of the flash discharge tube; said auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a second signal after a predetermined time period when the amount of light received by said photometric circuit during a flash photography operation is insufficient; and said auxiliary shutter closing means being responsive to said first and second signals to operate said shutter control circuit through the photometric circuit to close said shutter.

Claim 3

A camera according to claim 1 in which said auxiliary shutter closing means comprises a logic circuit for storing said first electrical signal supplied by said electronic flash unit, said timer circuit means including a timer pulse generator for supplying a reset pulse to said logic circuit upon the shutter release operation, a switching transistor which is turned on by said second signal and said first electrical signal which has been stored in said logic circuit, and a light emitting element which is operative to emit light when said transistor is turned on to supply light input to said light receiving element of said photometric circuit, thereby operating the photometric circuit.

Claim 4

A camera according to claim 2 in which the timer pulse generator comprises a reset circuit for producing a reset pulse, and a limiter circuit for producing said second signal.

Claim 5

A camera according to claim 3 in which both the reset circuit and the limiter circuit comprise resistor-capacitor timer circuits.

Claim 6

A camera according to claim 2 in which the logic circuit comprises a pair of flip flops together comprising four NAND circuits, and another NAND circuit and an inverter which couple the pair of flipflops together.

Claim 7

A camera according to claim 1, further comprising said electronic flash, in which the electronic flash unit comprises a connection terminal to which an illumination signal is applied for transmission to the camera, the illumination signal indicating the occurence of a flashlight illumination from the flash discharge tube.

Claim 8

A camera and an electronic flash unit, said camera comprising: a shutter; first means for detecting flashlight illumination reflected by a subject to be photographed, and auxiliary shutter closing means for enabling the closing of said shutter after a selected length of time when said reflected light is below a selected value for said selected length of time; said electronic flash unit providing a control signal to said auxiliary shutter closing means upon the occurrence of flashlight illumination; and said auxiliary shutter closing means including timer circuit means and being connected to said shutter for closing said shutter in response to said control signal and the output of said timer circuit means, said timer circuit means being responsive to the closure of a power switch of the camera in response to a shutter release operation for producing said output after said selected length of time.

Claim 9

A camera and an electronic flash unit, said camera comprising: a shutter; first means for detecting flashlight illumination reflected by a subject to be photographed, and auxiliary shutter closing means for enabling the closing of said shutter after a selected length of time when said reflected light is below a selected value for said selected length of time; said electronic flash unit providing a control signal to said auxiliary shutter closing means upon the occurrence of flashlight illumination; and said auxiliary shutter closing means including timer circuit means and being connected to said shutter for closing said shutter in response to said control signal and the output of said timer circuit means, said timer circuit means being responsive to the closure of a power switch of the camera in response to a shutter release operation for producing said output after said selected length of time.

Claim 10

A camera as claimed in claim 7, wherein said electronic flash unit has terminal means for providing said control signal.

Claim 11

A camera as claimed in claim 7, wherein said first means comprises a photocell.

Claim 12

A camera as claimed in claim 9, wherein said auxiliary shutter closing means comprises a light emitting element optically coupled to said photocell.

Claim 13

A camera as claimed in claim 7, wherein said auxiliary shutter closing means comprises a light emitting element.

Claim 14

A photographic apparatus including a camera with an electrical shutter and an electronic flash unit with a flash discharge tube for use with said camera, said apparatus comprising: a photometric circuit comprising a photocell adapted to receive light reflected by a subject to be photographed; an electrical shutter having the timing of the start of its closing operation controlled by an electromagnet; an electrical shutter control circuit of the nonmemory type responsive to an output of said photometric circuit for normally closing said shutter; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing a first signal in response to detecting said change of voltage; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a second signal after a predetermined time; and said auxiliary shutter closing means being operative when both said voltage detection circuit and said timer circuit means produce said first and second signals to forcibly close said shutter when its closing operation is not initiated within the period of said predetermined time after the initiation of said flashlight illumination.

Claim 15

A photographic apparatus including a camera with an electrical shutter and an electronic flash unit with a flash discharge tube for use with said camera, said apparatus comprising: a photometric circuit comprising a photocell adapted to receive light reflected by a subject to be photographed; an electrical shutter having the timing of the start of its closing operation controlled by an electromagnet; an electrical shutter control circuit of the nonmemory type responsive to an output of said photometric circuit for normally closing said shutter; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing a first signal in response to detecting said change of voltage; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a second signal after a predetermined time; and said auxiliary shutter closing means being operative when both said voltage detection circuit and said timer circuit means produce said first and second signals to forcibly close said shutter when its closing operation is not initiated within the period of said predetermined time after the initiation of said flashlight illumination.

Claim 16

A camera in combination with an electronic flash unit, said camera comprising: a photometric circuit comprising a photocell adapted to receive light coming from a subject to be photographed; an electrical shutter; an electrical shutter control circuit responsive to an output of said photometric circuit for normally closing said shutter; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a first signal after a predetermined time; first terminal means connected to said auxiliary shutter closing means for receiving a second signal from said electronic flash unit indicative of an occurrence of a flash illumination; and said auxiliary shutter closing means being operative in response to said first and second signals to forcibly close said shutter when said shutter closing operation is not initiated within the period of said predetermined time; said electronic flash unit comprising: a flash discharge tube; a trigger circuit for discharging said flash discharge tube; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing said second signal upon detecting said change of voltage; and second terminal means connected to said voltage detection circuit and adapted to be connected to said first terminal means for applying said second signal to said auxiliary shutter closing means to close said shutter.

Claim 17

A camera in combination with an electronic flash unit, said camera comprising: a photometric circuit comprising a photocell adapted to receive light coming from a subject to be photographed; an electrical shutter; an electrical shutter control circuit responsive to an output of said photometric circuit for normally closing said shutter; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a first signal after a predetermined time; first terminal means connected to said auxiliary shutter closing means for receiving a second signal from said electronic flash unit indicative of an occurrence of a flash illumination; and said auxiliary shutter closing means being operative in response to said first and second signals to forcibly close said shutter when said shutter closing operation is not initiated within the period of said predetermined time; said electronic flash unit comprising: a flash discharge tube; a trigger circuit for discharging said flash discharge tube; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing said second signal upon detecting said change of voltage; and second terminal means connected to said voltage detection circuit and adapted to be connected to said first terminal means for applying said second signal to said auxiliary shutter closing means to close said shutter.

Claim 18

An electronic flash unit for use with a camera, wherein said camera includes a first terminal for receiving a first signal from said electronic flash unit, a shutter, and auxiliary shutter closing means to close said shutter, said electronic flash unit comprising: a flash discharge tube; a trigger circuit and a main capacitor both for discharging said flash discharge tube; a voltage detection circuit including a coil and a diode interposed within a discharge path for discharging the charge of said main capacitor to said flash discharge tube, a signal producing capacitor connected in parallel to said flash discharge tube, a transistor connected to said discharge path which is activated by the discharge of said signal producing capacitor when said flash discharge tube is discharged, said voltage detection circuit detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and producing said first signal via said transistor in response to detecting said change of voltage; and a second terminal in said electronic flash unit for receiving said first signal from said transistor when activated and adapted to be connected to said first terminal of said camera, said second terminal applying said first signal via said first terminal to said auxiliary shutter closing means of said camera to close said shutter; a shutter; first means for detecting flashlight illumination reflected by a subject to be photographed, and auxiliary shutter closing means for enabling the closing of said shutter after a selected length of time when said reflected light is below a selected value for said selected length of time; said electronic flash unit providing a control signal to said auxiliary shutter closing means upon the occurrence of flashlight illumination; and said auxiliary shutter closing means including timer circuit means and being connected to said shutter for closing said shutter in response to said control signal and the output of said timer circuit means, said timer circuit means being responsive to the closure of a power switch of the camera in response to a shutter release operation for producing said output after said selected length of time.

Claim 19

An electronic flash unit for use with a camera, wherein said camera includes a first terminal for receiving a first signal from said electronic flash unit, a shutter, and auxiliary shutter closing means to close said shutter, said electronic flash unit comprising: a flash discharge tube; a trigger circuit and a main capacitor both for discharging said flash discharge tube; a voltage detection circuit including a coil and a diode interposed within a discharge path for discharging the charge of said main capacitor to said flash discharge tube, a signal producing capacitor connected in parallel to said flash discharge tube, a transistor connected to said discharge path which is activated by the discharge of said signal producing capacitor when said flash discharge tube is discharged, said voltage detection circuit detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and producing said first signal via said transistor in response to detecting said change of voltage; and a second terminal in said electronic flash unit for receiving said first signal from said transistor when activated and adapted to be connected to said first terminal of said camera, said second terminal applying said first signal via said first terminal to said auxiliary shutter closing means of said camera to close said shutter; a shutter; first means for detecting flashlight illumination reflected by a subject to be photographed, and auxiliary shutter closing means for enabling the closing of said shutter after a selected length of time when said reflected light is below a selected value for said selected length of time; said electronic flash unit providing a control signal to said auxiliary shutter closing means upon the occurrence of flashlight illumination; and said auxiliary shutter closing means including timer circuit means and being connected to said shutter for closing said shutter in response to said control signal and the output of said timer circuit means, said timer circuit means being responsive to the closure of a power switch of the camera in response to a shutter release operation for producing said output after said selected length of time.

Claim 20

An electronic flash unit in combination with a camera, the camera comprising: a photometric circuit comprising a photocell adapted to receive light coming from a subject to be photographed; an electrical shutter; an electronic shutter control circuit responsive to an output of said photometric circuit for normally closing said shutter; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a first signal after a predetermined time; first terminal means connected to said auxiliary shutter closing means for receiving a second signal from said electronic flash unit indicative of an occurrence of a flash illumination; and auxiliary shutter closing means being energized to ignition in response to said first and second signals to illuminate said photocell thereby to forcibly close said shutter when said shutter closing operation is not initiated within the period of said predetermined time; said electronic flash unit comprising: a flash discharge tube; a trigger circuit for discharging said flash discharge tube; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing said second signal upon detecting said change of voltage; and second terminal means connected to said voltage detection circuit and adapted to be connected to said first terminal means for applying said second signal to said auxiliary shutter closing means to close said shutter.

Claim 21

An electronic flash unit in combination with a camera, the camera comprising: a photometric circuit comprising a photocell adapted to receive light coming from a subject to be photographed; an electrical shutter; an electronic shutter control circuit responsive to an output of said photometric circuit for normally closing said shutter; auxiliary shutter closing means including timer circuit means for sensing a shutter release operation and in response thereto for producing a first signal after a predetermined time; first terminal means connected to said auxiliary shutter closing means for receiving a second signal from said electronic flash unit indicative of an occurrence of a flash illumination; and auxiliary shutter closing means being energized to ignition in response to said first and second signals to illuminate said photocell thereby to forcibly close said shutter when said shutter closing operation is not initiated within the period of said predetermined time; said electronic flash unit comprising: a flash discharge tube; a trigger circuit for discharging said flash discharge tube; a voltage detection circuit including a signal producing capacitor connected to a discharge path of said flash discharge tube for detecting a change of voltage of said discharge path which occurs when said flash discharge tube is discharged and for producing said second signal upon detecting said change of voltage; and second terminal means connected to said voltage detection circuit and adapted to be connected to said first terminal means for applying said second signal to said auxiliary shutter closing means to close said shutter.