Electronic flash control device employing a plurality of control signals

Abstract

An electronic flash control device makes sure that the emission of light of an electronic flash is not impaired by a noise component signal prior to generation of a suitable quantity of light by the flash. A trigger signal is applied by the control device to allow the flash to emit light. An enable signal is supplied to a quenching circuit a predetermined time after the noise of the trigger signal has been produced. When the quantity of light from an object to be photographed by the camera reaches a certain value and the enable signal occurs, the quench circuit suppresses the emission of light by the electronic flash.

What is claimed is: 
     
       1. An electronic flash control device for controlling an electronic flash used with a camera, said control device comprising: means for applying a trigger signal to said electronic flash to allow said electronic flash to emit light;   means for applying an enable signal at a predetermined time which occurs after a noise related to said trigger signal is produced.Iadd., said enable signal applying means initiating a counting of a time in response to said trigger signal, independent of a light emitting operation of said electronic flash, said enable signal being applied at said predetermined time.Iaddend.;   first means for generating a quench signal when a quantity of light from an object to be photographed reaches a predetermined value; and   second means for generating a final quench signal when both said enable signal and said quench signal are received.   
     
     
       2. An electronic flash control device as claimed in claim 1, wherein said predetermined time occurs at approximately a first instant of said emission of light. 
     
     
       3. An electronic flash control device as claimed in claim 1, wherein said predetermined time occurs a predetermined time period after said trigger signal has been generated. 
     
     
       4. An electronic flash control device as claimed in claim 2, wherein said predetermined time occurs a predetermined time period after said trigger signal has been generated. 
     
     
       5. An electronic flash control device as claimed in claim 3, wherein data used to determine said predetermined time period is stored in a memory located in said camera. 
     
     
       6. An electronic flash control device as claimed in claim 5, wherein said memory is an electrically erasable/programmable memory. 
     
     
       7. An electronic flash control device as claimed in claim 4, wherein data used to determine said predetermined time period is stored in a memory located in said camera. 
     
     
       8. An electronic flash control device as claimed in claim 7, wherein said memory is an electrically erasable/programmable memory. 
     
     
       9. An electronic flash control device as claimed in claim 1, wherein said camera is a TTL light control type camera. 
     
     
       10. An electronic flash control device as claimed in claim 1, wherein said camera is a silver salt photographic camera. 
     
     
       11. An electronic flash control device as claimed in claim 1, wherein said camera is an electronic still camera. 
     
     
       12. An electronic flash control device as claimed in claim 1, wherein said electronic flash is built in said camera. 
     
     
       13. An electronic flash control device as claimed in claim 1, wherein said electronic flash is an electronic flash which is not built in said camera. 
     
     
       14. An electronic flash control device as claimed in claim 1, wherein said enable signal allows said quench signal to be output. 
     
     
       15. An electronic flash control device as claimed in claim 1, wherein said enable signal allows said final quench signal to be output. 
     
     
       16. An electronic flash control device as claimed in claim 1, wherein said first means comprises: integrating means for integrating light from said object to be photographed so as to produce a signal corresponding to said quantity of light;   comparator means operatively coupled to said integrating means for comparing said signal corresponding to said quantity of light with said predetermined value; and wherein said second means comprises:   logical means operatively coupled to said comparator means and receiving said enable signal.   
     
     
       17. An . .electric.!. flash control device for controlling an electronic flash used with a camera.Iadd., .Iaddend.comprising: means for applying a trigger signal to said electronic flash to emit light;   means for applying an enable signal at a predetermined time which occurs after a noise related to said trigger signal is produced.Iadd., said enable signal applying means initiating a count of a time in response to said trigger signal, independent of a light emitting operation of said electronic flash, said enable signal being applied at said predetermined time; .Iaddend.   means for integrating a quantity of light from an object to be photographed;   means for generating a quench signal when said quantity of light reaches a predetermined value; and   second means for generating a final quench signal when both said enable signal and said quench signal have been generated,   said integrating means and said quench signal generating means being activated at the same time in response to said trigger signal.