US3919593A - Flash safety device in a flash apparatus - Google Patents

Flash safety device in a flash apparatus Download PDF

Info

Publication number
US3919593A
US3919593A US390711A US39071173A US3919593A US 3919593 A US3919593 A US 3919593A US 390711 A US390711 A US 390711A US 39071173 A US39071173 A US 39071173A US 3919593 A US3919593 A US 3919593A
Authority
US
United States
Prior art keywords
circuit
trigger
voltage
capacitor
flash
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US390711A
Other languages
English (en)
Inventor
Zenzo Nakamura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Application granted granted Critical
Publication of US3919593A publication Critical patent/US3919593A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/30—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp
    • H05B41/32—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp for single flash operation
    • H05B41/325—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp for single flash operation by measuring the incident light

Definitions

  • a flash voltage detector operates a switch which enables a flash triggering cir- [22] :18. C1. 315/241 P; 354/145 i only after the flash voltage reaches a Predetep l lt. C1. H951) 41/14 mined value
  • the Switch 1 held of Search 3 15/ 1' 241 354/145 includes a unidirectional element in series opposition to the triggering current flow.
  • the present invention relates to a flash safety device of a flash apparatus.
  • flashing is accomplished by boosting the low voltage of the battery to a higher voltage and then applying the electric charge to light a Xenon flash tube.
  • the required flash intensity can be obtained only after the capacitor is suitably charged.
  • a neon tube is used to indicate that the main capacitor has been charged to place it in readiness for flashing the tube.
  • this requires the photographer to divert his attention to the neon tube when he is taking continuous flash pictures. This is somewhat inconvenient and sometimes troublesome.
  • An object of the present invention is to provide a safety circuit for a flash apparatus in which a conducting element such as diode, etc. is connected to a flashing voltage detection circuit of the flash apparatus to automatically prevent flashing of the flash apparatus when the apparatus does not have prescribed flashing BRIEF DESCRIPTION OF THE DRAWINGS
  • the sole drawing is an arrangement drawing of a safety circuit of the flash circuit apparatus according to the present invention.
  • FIG. 1 shows a low voltage actuation power source such as battery, etc.
  • 2 is a main switch of a flash apparatus
  • 3 is a conventionally known booster circuit
  • 4 is a rectifier diode
  • 5 is a flashing main capacitor
  • 6 are bleeder resistors for detecting capacitor terminal voltage
  • 8 is a neon tube
  • 9 is a Xenon tube
  • 10 is a current limiting resistance
  • 11 is a trigger capacitor
  • 12 is a trigger transformer
  • 13 is a triggering thyristor
  • I4 15 are resistances
  • 16, 19 are switching transistors
  • l7, 18 are emitter, collector resistances of the transistor 16.
  • Member 20 is an FET
  • 21 is a resistance connected in parallel with a temperature compensation diode 22.
  • Component 23 is an adjusting resistance
  • 24 is a switching transistor
  • 25 is a diode as an one way conducting element.
  • Reference character 25A identifies a circuit within a camera, wherein 26 is an exposure meter circuit battery, 27 is a synchronizing switch, 28 is a variable resistance which is varied depending on distance to an object, 29 is an exposure meter, and CdS shows a light receiving element to sense light from an object.
  • both FET20 and the transistor 24 are retained in OFF state, therefore voltage will not be impressed on the transistor 24.
  • the synchronizing switch '27 is closed, since the diode 25 is connected in a reverse direction in a circuit of the trigger starting circuit battery 26 synchronizing switch 27 resistance 14 SCR13 diode 25 battery 26, starting current will not flow to the SCR13 and the Xenon tube 9 is not lighted.
  • the terminal voltage of the capacitor 5 is elevated to a prescribed value or higher, the neon tube 8 is lighted and the tran sistors l6, 19 are turned ON. As a result current from the power source 1 flows to the drain of the FET 20 and the collector of the transistor 24.
  • the diode 25 conducts the collector current of the transistor 24.
  • the collector current of the transistor 24 is almost proportional to the terminal voltageof the capacitor 5.
  • the voltage across'the diode 25 will correspond to the voltage of the capacitor 5 logarithmically with the compression characteristics of the diode 25. This voltage will be impressed upon to the circuit 25A in the camera.
  • the exposure meter 29 is positioned based on the resistance value of the distance resistance 28 and the sum of the voltage across the diode 25 and the voltage of the battery 26, indicating the aperture value by its pointer position. Therefore, the diaphragm aperture of a camera is adjusted based on this indication.
  • the aperture value for flash auto-photographing can be set based on the distance to an object, and the terminal voltage of the capacitor 5 which voltage corresponds to the amount of light to be emitted by the flash.
  • the flash triggering is prevented until the flash apparatus is placed in flashable state by such one way conducting element as diode 25, etc. to prevent unnecessary loss of energy at the power sourc'e by inadequate flashing, thus it is very useful in practical application.
  • the one way conducting element beside the above mentioned diode naturally such elements as having one way conducting function by continuance of its terminals for example SCR transistor, etc. can be used.
  • a flash apparatus comprising:
  • a trigger circuit coupled to said flash tube and capable of igniting said flash tube when the trigger circuit is enabled and a synchronizing signal applied to the circuit, said circuit including a capacitor for accumulating triggering energy, said capacitor being supplied with triggering energy, said trigger circuit including means for applying the energy to the flash tube when the circuit is enabled and the synchronizing signal applied,
  • a voltage detecting means coupled to said main capacitor for detecting the voltage across said main capacitor so as to emit an output therefrom corresponding to the voltage across said main capacitor
  • a switching means connected between the output of said voltage detecting means and said trigger circuit andswitchable to an ON state when the output a of said voltage detecting means reaches a predetermined value so as to enable said trigger circuit.
  • said voltage detecting means contains a bleeder circuit coupled across the flash tube, said bleeder circuit being composed of a plurality of resistances and having an output terminal, the output terminal of said bleeder circuit being coupled to said switching means.
  • a flash apparatus comprising: i
  • a trigger circuit coupled to said flash tube and capable of igniting said flash tube when the trigger circuit is enabled and a synchronizing signal applied ,tojthe circuit, said circuit including a trigger capacfitor for accumulating triggering energy, means connecting said capacitor to the supply means for supplying triggering energy thereto, said trigger circuit including means connected with said flash tube and to said triggercapacitor for applying the triggering energy when said circuit is enabled and actuated so as to light said flash tube, v :a voltage detecting means connected with said main capacitor for detecting the terminal voltage of said main capacitor so as to produce an output therea from corresponding to the terminal voltage of said main capacitor,
  • a switching means connected with said voltage detecting means and switchable to an ON state when the output of said voltage detecting means reaches a predetermined value, a constant current circuit, said circuit being connected in said switching means and generating a constant current when said switching means is turned to the ON state,
  • a unidirectionally conducting element said element being connected with said constant current circuit in the forward direction and being turned to an ON state when the constant current circuit generates constant current so as to generate a constant voltage
  • a synchronizing switch means coupled to said triggering circuit for producing the synchronizing signal
  • a trigger starting means in said trigger circuit for forming a path of trigger starting current to cause said trigger starting current to flow therethrough when said synchronizing switch means is turned to the ON state so as to actuate said trigger circuit, said starting means connecting said unidirectional element within the path of said trigger starting current to vary said trigger starting current, said starting means causing said trigger starting current to flow through said path in order to actuate said trigger circuit when said unidirectional element and said synchronizing switch means respectively are turned to the ON state.
  • a flash circuit comprising a gas discharge lamp, a main capacitor coupled across the lamp, a capacitor charging circuit coupled across the capacitor, a threshold voltage detector coupled across the capacitor and including a threshold voltage responsive switch whose state is changeable in response to the capacitor voltage reaching a predetermined value, a actuable trigger circuit coupled to the lamp and forming a trigger path, a unidirectional element in the trigger path, characterized in that said unidirectional element is directed to oppose trigger current flow and is connected to said detector to receive forward current from the switch as the switch is switched when the main capacitor exceeds the switchs threshold level.

Landscapes

  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
  • Exposure Control For Cameras (AREA)
  • Stroboscope Apparatuses (AREA)
US390711A 1972-08-28 1973-08-23 Flash safety device in a flash apparatus Expired - Lifetime US3919593A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1972100203U JPS525644Y2 (hr) 1972-08-28 1972-08-28

Publications (1)

Publication Number Publication Date
US3919593A true US3919593A (en) 1975-11-11

Family

ID=14267733

Family Applications (1)

Application Number Title Priority Date Filing Date
US390711A Expired - Lifetime US3919593A (en) 1972-08-28 1973-08-23 Flash safety device in a flash apparatus

Country Status (2)

Country Link
US (1) US3919593A (hr)
JP (1) JPS525644Y2 (hr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3969737A (en) * 1974-08-01 1976-07-13 Eastman Kodak Company Electronic flash unit for cameras adapted to receive flashbulbs
US4047194A (en) * 1974-05-08 1977-09-06 Canon Kabushiki Kaisha Camera system with means for automatically switching to flash operation
US4156565A (en) * 1978-03-23 1979-05-29 Polaroid Corporation Control system for flash-illuminated automatic focusing camera
FR2450028A1 (fr) * 1979-02-20 1980-09-19 Fuji Photo Optical Co Ltd Circuit de commande pour un dispositif de lampe eclair electronique automatique
EP0035224A1 (en) * 1980-02-29 1981-09-09 Olympus Optical Co., Ltd. Electronic flash apparatus
US4464609A (en) * 1975-10-02 1984-08-07 Canon Kabushiki Kaisha Flash lighting unit for a camera

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3593061A (en) * 1968-02-23 1971-07-13 Nippon Kogaku Kk Apparatus for increasing the lighting of photoflash discharge lamps
US3690237A (en) * 1970-09-22 1972-09-12 Zydichi Fuwa Electronic flashlight device for flashlight photography
US3714872A (en) * 1969-04-18 1973-02-06 Canon Kk Photographic flash exposure control system
US3723810A (en) * 1970-12-08 1973-03-27 Canon Kk Electronic flash device
US3751714A (en) * 1971-11-24 1973-08-07 D Cooper Electronic photoflash unit
US3764849A (en) * 1972-03-24 1973-10-09 Minolta Camera Kk Electronic flash charging and triggering circuitry
US3777212A (en) * 1971-06-18 1973-12-04 Canon Kk Electronic flash device
US3778672A (en) * 1972-07-27 1973-12-11 Ponder & Best Audible alert signal for an electronic flash unit
US3814985A (en) * 1971-10-20 1974-06-04 Metz Apparatewerke Electronic flash unit having protective circuit for flash terminating switch
US3819983A (en) * 1970-09-08 1974-06-25 Polaroid Corp Photoflash power supply

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3593061A (en) * 1968-02-23 1971-07-13 Nippon Kogaku Kk Apparatus for increasing the lighting of photoflash discharge lamps
US3714872A (en) * 1969-04-18 1973-02-06 Canon Kk Photographic flash exposure control system
US3819983A (en) * 1970-09-08 1974-06-25 Polaroid Corp Photoflash power supply
US3690237A (en) * 1970-09-22 1972-09-12 Zydichi Fuwa Electronic flashlight device for flashlight photography
US3723810A (en) * 1970-12-08 1973-03-27 Canon Kk Electronic flash device
US3777212A (en) * 1971-06-18 1973-12-04 Canon Kk Electronic flash device
US3814985A (en) * 1971-10-20 1974-06-04 Metz Apparatewerke Electronic flash unit having protective circuit for flash terminating switch
US3751714A (en) * 1971-11-24 1973-08-07 D Cooper Electronic photoflash unit
US3764849A (en) * 1972-03-24 1973-10-09 Minolta Camera Kk Electronic flash charging and triggering circuitry
US3778672A (en) * 1972-07-27 1973-12-11 Ponder & Best Audible alert signal for an electronic flash unit

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4047194A (en) * 1974-05-08 1977-09-06 Canon Kabushiki Kaisha Camera system with means for automatically switching to flash operation
US3969737A (en) * 1974-08-01 1976-07-13 Eastman Kodak Company Electronic flash unit for cameras adapted to receive flashbulbs
US4464609A (en) * 1975-10-02 1984-08-07 Canon Kabushiki Kaisha Flash lighting unit for a camera
US4156565A (en) * 1978-03-23 1979-05-29 Polaroid Corporation Control system for flash-illuminated automatic focusing camera
FR2450028A1 (fr) * 1979-02-20 1980-09-19 Fuji Photo Optical Co Ltd Circuit de commande pour un dispositif de lampe eclair electronique automatique
EP0035224A1 (en) * 1980-02-29 1981-09-09 Olympus Optical Co., Ltd. Electronic flash apparatus

Also Published As

Publication number Publication date
JPS4958343U (hr) 1974-05-23
JPS525644Y2 (hr) 1977-02-05

Similar Documents

Publication Publication Date Title
US3846811A (en) Flash unit for use with camera
US3710701A (en) Flash device for a camera and a photographing system with an artificial illuminator
US3568582A (en) Electronic shutter
US3340426A (en) Control system for terminating the discharge through a flash lamp
US3953864A (en) Camera device having a photographic flash device combined therewith
US3350604A (en) Flash lamp controlled by photosensitive light integrating device
US4540265A (en) Energy-saving electronic flash apparatus
JPS5652740A (en) Camera having data imprinting device
NL8003593A (nl) Elektrische flitsinrichting voor camera's.
US3648104A (en) Electronic flash unit with preliminary flash for automatic timing
US4302084A (en) Automatic rangefinding device for use in a camera
KR970006278B1 (ko) 충전량에 따라 자동 발광하는 카메라 및 그 제어방법
JPS58190931A (ja) オ−トストロボの露光適否表示装置
US3919593A (en) Flash safety device in a flash apparatus
US4228381A (en) Flash tube apparatus with delayed emission
US3651372A (en) Warning indicator apparatus for use in a camera having a flash discharge device contained therein
US4100459A (en) Indicator circuit for electronic flash apparatus
US4295724A (en) Electric self-timer device for cameras
US3690237A (en) Electronic flashlight device for flashlight photography
US4351600A (en) Flash output control failure warning device of an automatic flash output control speed light
US3541386A (en) Control system for terminating the discharge of a flash lamp
US4210849A (en) Electronic control circuitry for terminating flash output
US3748978A (en) Exposure time controls for cameras operating with flash illumination
US4162426A (en) Zone responsive, light-sensing circuit for controlling flash photographing
US4377774A (en) Electronic flash control device