US3906292A - Device for controlling lighting time of lamp - Google Patents

Device for controlling lighting time of lamp Download PDF

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Publication number
US3906292A
US3906292A US412097A US41209773A US3906292A US 3906292 A US3906292 A US 3906292A US 412097 A US412097 A US 412097A US 41209773 A US41209773 A US 41209773A US 3906292 A US3906292 A US 3906292A
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United States
Prior art keywords
voltage
circuit
power source
resistor
lamp
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Expired - Lifetime
Application number
US412097A
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English (en)
Inventor
Akira Takahashi
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.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
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Publication date
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Publication of US3906292A publication Critical patent/US3906292A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/1563—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators without using an external clock

Definitions

  • the control voltage and the reference voltage of the switching circuit are derived from the junction between the charging-discharging circuit and the resistor connected in series thereto and the junction between the device for obtaining a constant voltage and the resistor connected in series thereto, respectively.
  • the voltage difference between said two junctions is increased so that the on time of the switching circuit is increased, thereby increasing the lighting time of the lamp.
  • FIG. 1 A first figure.
  • the present invention relates to a device for controlling a lighting time of a lamp.
  • An illumination device incorporating the so-called CR discharge type timer consisting of a capacitor and a resistor connected in parallel thereto is used in a camera of the type capable of superimposing desired data such as dates upon a film together with a subject.
  • a trigger switch is actuated in response to the shutter release operation or by a suitable actuating member to energize the illumination device to turn on a lamp, thereby illuminating desired data to be superimposed upon a film.
  • the voltage of the power source for the illumination device drops, the quantity of light emitted from the lamp is reduced and the lighting or on time of the lamp, which is determined by the CR timer, is also decreased, resulting in the underexposure of the data to be superimposed.
  • the present invention provides an improved device for controlling a lighting time of a lamp, in which a device for obtaining a constant voltage is inserted into a CR timer so that the on time interval of the timer may be increased as the voltage drop of the power source is increased, thereby preventing the drop in quantity of light emitted from the lamp.
  • a charging-discharging circuit adapted to be charged to a predetermined constant voltage when a trigger switch is closed and to start the discharge as soon as the trigger switch is opened, a switching circuit for controlling the current flowing through a lamp, and a series circuit consisting of a resistor and a device such as a zener diode for obtaining a constant voltage, are connected to parallel to each other and to a DC power source.
  • the base of a switching element in the first stage of the switching circuit is connected to the chargingdischarging terminal to be referred to as the point a hereinafter of the charging-discharging circuit, and the emitter is connected to the junction of the device such as a zener diode for obtaining a constant voltage and the resistor in said series circuit. (the latter junction will be referred to as the point b hereinafter.)
  • the switching element is turned on when the voltage difference between the points a and b is within a predetermined range, so that a lamp is turned on.
  • the voltage at the point b varies as the voltage of the DC power source varies.
  • the charging-discharging circuit is always charged to a predetermined constant voltage so that the larger the voltage drop of the DC power source. the longer the time when the voltage at the points a and b are equal becomes. As a result, the lighting time of the lamp is increased accordingly.
  • FIG. 1 is a circuit diagram of a first embodiment of the present invention
  • FIG. 2 is a graph used for the explanation of the mode of operation thereof.
  • FIG. 3 is a circuit diagram of a second embodiment of the present invention.
  • FIG. 1 is a diagram of a circuit for turning on a lamp L in order to superimpose the data such as date upon a film loaded in a camera.
  • SW is a trigger switch which is closed for a very short time and then opened in response to a shutter release operation or by a suitable actuating member.
  • R is a resistor; R a variable resistor; R a resistor; C, a capacitor connected in parallel with the variable resistor R D,, a device such as a zener diode for obtaining a predetermined constant voltage connected in parallel with the variable resistor R and the capacitor C; Tr, and Tr NPN transistors; and Tr a PNP transistor.
  • E is a power source
  • D a device, such as a zener diode for obtaining a predetermined constant voltage, connected in parallel with the lamp L and the transistor Tr and connected in series to the resistor R and the power source E.
  • the voltage charged across the capacitor C is always E
  • the voltage at the junction 0 at the base of the transistor Tr, the resistor R, and the capacitor C, is higher than the voltage at the junction b at the zener diode D the emitter of the transistor Tr, and the resistor R
  • the voltage at the junction b is lower than the voltage of the power source E by a voltage drop across the zener diode D
  • the base voltage of the NPN transistor Tr is higher than the emitter voltage so that the transistors Tr, Tr and Tr are turned on.
  • the lamp L is thus turned on.
  • the second embodiment whose circuit diagram is shown in FIG. 3 is substantially similar in arrangement to the first embodiment except that a transistor Tr with a differentiating circuit consisting of a capacitor C and a resistor R is inserted in place of the switch SW. Therefore when the trigger switch SW is closed, the differentiated voltage is applied to the base of the transistor Tr, so that even when the trigger switch SW is closed for a relatively long time, the lamp L is turned on for a time interval corresponding to the voltage of the power source.
  • the decrease in quantity of light emitted from the lamp L due to the voltage drop of the power source may be compensated by varying the resistance of the variable resistor R and by selecting suitable zener diodes D and D
  • the service life may be increased and the failure in data superimposition may be prevented.
  • the PNP and NPN transistors may be used with the polarities of the power source and zener diodes reversed.
  • a Device for controlling a lighting time interval of a lamp comprising;
  • a charging-discharging circuit and a trigger switch connected in series, the series combination being connected in parallel with said DC power source and charged to a constant predetermined voltage when the trigger switch is closed, and then dis charged when the trigger switch is opened;
  • a switching circuit having two states connected to said charging-discharging circuit;
  • a lamp connected to said switching circuit so as to be turned on and off in response to the state of said switching circuit
  • a series circuit comprising a resistor and means for obtaining a constant voltage.
  • said series circuit being connected in parallel with said DC power source to obtain a voltage at the junction of the resistor and the constant voltage means which is the voltage of the DC power source less the constant voltage drop of said constant voltage means;
  • a switching element having a control terminal and a reference terminal in said switching circuit, said control terminal being connected to said chargingdischarging circuit and said reference terminal being connected to the junction between said means for obtaining a constant voltage and said resistor, the difference between the voltage at the control terminal and the voltage at the reference terminal being an inverse function of said DC power source voltage output and the voltage difference controlling the state of said switching circuit such that said switching circuit turns on said lamp for a longer time interval as said DC power source voltage output decreases.
  • said charging-discharging circuit comprises:
  • a device as defined in claim 1 wherein said trigger switch comprises a switch and circuit means for providing a differentiated output pulse, the duration of said pulse being substantially independent of the duration of activation of said trigger switch.
  • circuit means comprises:
  • a differentiating circuit activated by said switch and connected to the base of said transistor.
  • a device as in claim 2 wherein said means for obtaining a constant voltage is a zener diode.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Camera Data Copying Or Recording (AREA)
  • Light Sources And Details Of Projection-Printing Devices (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Electronic Switches (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
US412097A 1972-11-06 1973-11-02 Device for controlling lighting time of lamp Expired - Lifetime US3906292A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47110250A JPS5136551B2 (enrdf_load_stackoverflow) 1972-11-06 1972-11-06

Publications (1)

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US3906292A true US3906292A (en) 1975-09-16

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Application Number Title Priority Date Filing Date
US412097A Expired - Lifetime US3906292A (en) 1972-11-06 1973-11-02 Device for controlling lighting time of lamp

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US (1) US3906292A (enrdf_load_stackoverflow)
JP (1) JPS5136551B2 (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217523A (en) * 1976-11-18 1980-08-12 West Electric Co., Ltd. Photographic flash device
US4377774A (en) * 1976-10-15 1983-03-22 Minolta Camera Kabushiki Kaisha Electronic flash control device
US4590407A (en) * 1983-03-18 1986-05-20 Tektronix, Inc. Scale illumination lamp control circuit for an oscilloscope
US4598198A (en) * 1984-05-21 1986-07-01 Banner Engineering Corp. Automatic power control for modulated LED photoelectric devices

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52137756U (enrdf_load_stackoverflow) * 1976-04-14 1977-10-19
JPS5584623U (enrdf_load_stackoverflow) * 1979-12-13 1980-06-11
JPS58190933A (ja) * 1982-04-30 1983-11-08 Seiko Epson Corp カメラのデ−タ写し込み装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2923863A (en) * 1957-10-24 1960-02-02 Cons Electronics Ind Transistorized timing circuit
US3192449A (en) * 1962-08-13 1965-06-29 Lab For Electronics Inc Timing circuit

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2923863A (en) * 1957-10-24 1960-02-02 Cons Electronics Ind Transistorized timing circuit
US3192449A (en) * 1962-08-13 1965-06-29 Lab For Electronics Inc Timing circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4377774A (en) * 1976-10-15 1983-03-22 Minolta Camera Kabushiki Kaisha Electronic flash control device
US4217523A (en) * 1976-11-18 1980-08-12 West Electric Co., Ltd. Photographic flash device
US4590407A (en) * 1983-03-18 1986-05-20 Tektronix, Inc. Scale illumination lamp control circuit for an oscilloscope
US4598198A (en) * 1984-05-21 1986-07-01 Banner Engineering Corp. Automatic power control for modulated LED photoelectric devices

Also Published As

Publication number Publication date
JPS5136551B2 (enrdf_load_stackoverflow) 1976-10-08
JPS4968568A (enrdf_load_stackoverflow) 1974-07-03

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