JPS6158820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to a new electronic flash device for photography, particularly for photographic illumination.

BACKGROUND TECHNOLOGY An electronic flash device using a gas discharge tube is
It is a very useful primary or auxiliary light source for photography. Such devices can be small, lightweight, and with a suitable power source can perform a large number of exposures over long periods of time.

For most purposes, it is desirable for the camera and flash device to be completely portable and independent from the surroundings. Therefore, primary or secondary batteries are commonly used as a power source for operating flash devices.

One important factor limiting the usefulness of battery-powered electronic flash devices is the amount of time the device can be used effectively without replacing or recharging the batteries. Another factor that is important to the user is cycle time, or the minimum required time between flashes. The cycle time is essentially the time required to recharge the charging capacitor with enough energy to produce a light flash of the required intensity when the charging capacitor is discharged through the gas-filled flash tube.

The battery power supply is designed to generate voltages that are much lower than those required to operate the flash tube. The required high voltage is usually obtained from the battery voltage by a DC-to-AC converter connected between the battery and the capacitor charging circuit and including a voltage amplification transformer. Such charging networks typically draw a large initial current from the battery, but this current gradually settles to a lower steady state value. The steady-state value depends on all the losses in the charging circuit, especially on the leakage current in the charging capacitor. This steady state current flows until the device is triggered to flash, thereby again demanding an initial high current from the battery.

For a typical device using a nominal 6V battery power supply, the maximum required battery current is approximately 1.5A;
Standby current in steady state is approximately 100mA. Such a steady-state current is obviously very small compared to the full-load current, and the power consumption of the battery is therefore correspondingly low. However, certain flash devices require 10 seconds to fully charge.
Suppose you request an average current consumption of 1.5A at 5V. The energy required from the battery for a single flash would then be 75 watts-seconds if the device were triggered at the same time as a full charge. With a steady state current of 100 mA, the same amount of additional energy, or 75 watt-seconds, will be dissipated from the battery if the device is fully charged and left for only 2 minutes and 30 seconds.

OBJECTIVES AND DISCLOSURE OF THE INVENTION It is common for photographers to start up and leave electronic flash devices until they are ready to take a photo. be. Also,
Although the device is left in place for the entire exposure time, it still requires a minimum cycle time between exposures for recharging. The aim of the invention is to save a large part of the power normally lost in this way without reducing the speed of taking pictures, thereby extending the life of the battery and thus reducing the number of its replacement or recharging. That's true.

Briefly stated, the above and other objects of the present invention are achieved by a new strobe charging circuit that consumes essentially no power until a manual pushbutton is pressed. Therefore, the charging circuit is designed to charge the charging capacitor of the flash tube in the strobe device. Once the strobe device is triggered to produce a flash, the charging circuit is disabled so that again, substantially no power is dissipated. It would be desirable to have a device that automatically disables the charging circuit when the capacitor is charged and the user does not take a photo within a predetermined period of time. A short time later, by pressing the push button, the device is ready for flashing within less than the normal cycle time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the apparatus according to the invention, and its mode of operation, will be best understood by the following detailed description of the preferred embodiment thereof, taken in conjunction with the drawings.

Referring to FIG. 1, there is shown a camera 1 of ordinary conventional construction, which includes a lens 2.
A conventional shutter pushbutton S1 is provided. Pushbutton S1 may be an electrical switch, a mechanical actuator, or a combination thereof, depending on the type of camera used.

The camera 1 is fitted with a strobe device, generally indicated at 3, which includes a suitable flash tube K1, such as a conventional xenon-filled 300V flash tube. Pipe K1
is placed in a suitable reflector 4 behind a suitable conventionally designed lens 5 which directs the light from the lamp K1 into the viewing angle of the taking lens 2 of the camera.

The preparation lamp K2 may be a conventional neon-filled discharge tube and is visible through a suitable hole in the device 3. A pushbutton S2, such as a manual spring return pushbutton switch, is also mounted on the device 3.

The internal structure and mode of operation of the device, which has just been generally described, will be described in detail below. From the user's point of view, the operation consists of first momentarily pressing the pushbutton S2, waiting until the readiness lamp K2 comes on to indicate that the flash device is ready for operation, and then pressing the pushbutton S1 to perform exposure.

FIG. 2 shows a control device for the apparatus of FIG. Power for this control device is supplied by one or more conventional batteries B connected in series or in parallel. The battery may be of primary or secondary type or a combination thereof. Battery B shown for explanation
The negative terminal is grounded and the positive terminal potential (B+) is connected to each circuit in FIG. 2 as indicated by the symbols.

Battery B can be located in the strobe device 3, in the camera 1, or in a cassette containing a film unit for use in the camera. Once in place in any case, the battery is connected to the circuitry of the strobe device of FIG. 2 as shown.

The strobe device of FIG. 2 basically includes a voltage converter energized by battery B to create a relatively high voltage alternating current from the battery's relatively low voltage. This voltage converter also has a transformer T1 and a transistor Q1 which is connected as an oscillator as will be explained later.

The oscillator start-up circuit includes capacitor C1 and resistor R2. The oscillator is tuned by capacitor C2. A rectifier, shown as diode D1, is provided to take power from the oscillator output circuit and supply it for charging capacitor C3.

The camera 1 is assumed to be equipped with a conventional exposure control system, generally indicated at 14, which controls the shutter of the camera in response to actuation of a pushbutton S1 to open the flash tube K1 suitable for discharge. When the switch S3 is opened to the maximum, close the switch S3. When switch S3 is closed, a ground level trigger pulse is provided to the strobe device, discharging capacitor C3 through flash tube K1.

To explain in more detail, the transistor Q1 is
It is of pnp type, its collector is grounded and its emitter returns to B+ through the low voltage primary winding L1 of transformer T1. The transformer T1 has a tapped secondary winding having a high voltage section L2 and a low voltage section L3.

The tap at the connection between high pressure part L2 and low pressure part L3 is
It is connected to the base of transistor Q1 through resistor R1 and diode D2. As shown, diode D2 has its anode connected to the base of transistor Q1, so that it preferentially conducts current in the same direction as the emitter-base junction of the transistor.

Purpose of diode D2 and transistor Q
The purpose of the arrangement of winding L1 with respect to The purpose is to enable the transistor Q1 to be controlled by the battery voltage of B+). Avoiding such additional impedance minimizes the difference between the battery voltage and the voltage applied to winding L1.

The npn transistor Q2 has its collector at B+
and its emitter is connected to the cathode of diode D2. transistor Q
When the emitter of diode D2 is forward biased with respect to its base, the cathode of diode D2 will be close to (B+) and therefore transistor Q1 will not conduct.

The base of transistor Q2 is connected to a logic 0 of a conventional flip-flop 6, which is controlled in a manner described below.
is connected to the output terminal of the flip-flop and produces a logic 1 signal (positive with respect to earth) at its logic 0 terminal when the flip-flop is reset by a positive pulse applied to its reset input terminal R; Its logic 0 when the flip-flop is set by a positive pulse applied to its set input terminal S.
generates substantially earth-level voltage at its output terminal.

From the upper terminal of the secondary winding L2 of the transformer T1, through the capacitor C1 connected in series with capacitor 2 and capacitor C2, to the lower terminal L3 of the secondary winding.
A circuit is formed leading to the lower terminal of. The upper terminal of capacitor C1 is connected to the collector of npn transistor Q4 via resistor R2. The emitter of transistor Q4 is grounded as shown.

The base of transistor Q4 is connected to the anode of Zener diode D3. The cathode of diode D3 is connected to the active output terminal of a conventional one-shot multivibrator 15. When multivibrator 15 is triggered in the manner described below, it generates a positive pulse causing Zener diode D3 to breakdown and conduct current in the reverse direction, switching transistor Q4 into conduction.

With the above arrangement, the Zener diode D
3 breaks down biasing the base of transistor Q4 positively with respect to its emitter, a pulsed current flows through resistor R2 charging capacitor C1 to the opposite polarity as shown. This pulse is used to start the oscillator in the manner described below.

The charging circuit for capacitor C3 extends from the upper terminal of winding L2, from the anode to the cathode of diode D1, through capacitor C3, through capacitor C1, and back to the lower terminal of the secondary winding of transformer T1. . This circuit serves to charge capacitor C3 when the top terminal of the secondary winding of transformer T1 is positive with respect to the top terminal of capacitor C3.

Preparation lamp K2 is connected to the upper terminal of capacitor C3 via resistor R3 and to the lower terminal of capacitor C3 via resistor R4. At a predetermined voltage sufficient to start the flash tube K1, the lamp K
2 discharges and emits light indicating the device is ready for exposure.

Discharge tube K1 has a load terminal including a cathode connected to the lower terminal of capacitor C3 and an anode connected to the upper terminal of capacitor C3. The trigger grid of the discharge tube is routed to the (B+) terminal through the secondary winding L4 of the pulse transformer T2. The primary winding L5 of the transformer T2 is
It is connected between the power supply terminal (B+) and one terminal of the capacitor C4. The other terminal of capacitor C4 is connected to the cathode of diode D1 through current limiting resistor R5.

Capacitor C4 is charged such that its upper terminal is positive with respect to the (B+) terminal as capacitor C3 is charged. When a ground-level trigger pulse is applied to the trigger input terminal at the junction of capacitor C4 and resistor R5, capacitor C4 is rapidly discharged, causing a pulse of current to flow into the primary winding L5 and the secondary winding. For example, both ends of line L4
Induce an oscillatory ringing pulse with a maximum amplitude of 5000V. This excites the grid of the discharge tube K1, causing the discharge tube to discharge and perform a flash exposure.

When a flash occurs, capacitor C3 is discharged and lamp K2 is extinguished. The voltage across resistor R4 drops generating a signal that is used in the manner described below to de-energize the charging circuit.

Pushbutton S2 is connected between the power terminal of (B+) and the active input terminal of one-shot multivibrator 15. At the rising edge of the pulse generated when switch S2 is momentarily closed, one-shot multivibrator 15 is triggered to generate a positive going output pulse and set flip-flop 6. This pulse is also connected to the aforementioned Zener diode D3 and npn
It is also added to the base of transistor Q3. The collector of transistor Q3 is connected to the (B+) power supply terminal. The emitter of transistor Q3 is connected to the earth through capacitor C5.

Capacitor C5 is thus one shot.
When multivibrator 15 generates an output pulse to cause transistor Q3 to conduct, it is quickly charged. The time constant of the multivibrator 15 is
Capacitor C5 is chosen to charge to a voltage close to (B+) before transistor Q3 is turned off at the end of the pulse from multivibrator 15.

The voltage across capacitor C5 is applied to the active input terminal of conventional Schmitt trigger circuit 10 through resistor R6. The Schmitt trigger generates a "high" voltage signal that is positive with respect to ground when the input signal goes above the turn-on value, and a "low" voltage signal near ground when the input signal goes below the turn-off value. Configured to produce output. For purposes of the present invention, the turn-on and turn-off values of Schmitt trigger 10 may be substantially the same. capacitor C5,
Resistor R5 and the input impedance of the Schmitt trigger 10 provide a time constant of, for example, 1 to 2 minutes during which the voltage at the input of the Schmitt trigger 10 rises from a value well above its turn-on point to its turn-on point. The voltage is selected to drop to the off-point voltage.

The active output terminal of the Schmitt trigger 10 is
It is connected to one input terminal of the OR gate 8 of the pulse conversion. Each gate 8 has a resistor R.
There are three capacitors C6, C7 and C8 with one terminal connected via 7 to ground. The other terminals of capacitors C6, C7, C8 serve as active input terminals of gate 8. The cathode of diode D4 is connected to the connection between resistor R7 and capacitors C6, C7, and C8. The anode of diode D4 is connected to the active output terminal of gate 8.

When any input terminal of gate 8 is at ground potential, it appears across resistor R7 and across diode D.
The negative pulse sent by
Trigger the shot multivibrator 7 to generate a positive output pulse. This pulse resets flip-flop 6.

The power terminal (B+) is connected to the input terminal of a conventional one-shot multivibrator 9. The multivibrator 9 operates when a new battery is inserted for the first time and power is applied to the circuit for the first time.
An output pulse is generated at the leading edge of the rising edge of the (B+) power supply voltage transition. The return of the pulse from the multivibrator 9 serves to reset the flip-flop 6, ensuring that the device starts in the proper condition.

The third input terminal of OR gate 8 is connected to resistor R4.
and the preparation lamp K2. With this circuit, the multivibrator 7 is triggered when the capacitor C3 is discharged through the flash tube K1 and the lamp K2 is thereby extinguished.

Having thus described the structure of this embodiment of the invention, its operation will now be described.

First, when switch S2 is opened and switch S3 is opened, the device turns off transistors Q1 and Q2 and enters a standby state. flip flop 6
is reset, transistors Q3 and Q4 are cut off, and the output terminal of Schmitt trigger 10 is at a low voltage. Under these conditions, the battery draws the small amount of current necessary to keep the low level logic circuitry in operation. If desired, switch S1 may supplement an on-off switch connected in series with battery (B) to interrupt this small current. However, this improvement is not essential for practical use, and from the user's point of view, it makes the operation of the apparatus of FIG. 1 even more complicated, which increases the risk of operational errors.

When switch S2 is temporarily closed, one
Shot multivibrator 15 generates an output pulse (start signal). This pulse sets flip-flop 6, causing transistor Q3 to conduct until capacitor C5 rises to a voltage close to (B+). The Schmidt trigger 10 generates a positive output signal relative to the earth,
This has no effect on other circuits.

The pulse from the multivibrator 15 is also applied to the cathode of the Zener diode D3,
Diode D3 breaks down, allowing current to flow in the opposite direction, and transistor Q4 becomes conductive. The charging pulse for capacitor C1 thus flows from the (B+) supply terminal through capacitor C1, through resistor R2, and through the collector-emitter path of transistor Q4 to ground.

The negative voltage at the upper terminal of capacitor C1 now passes through lower L3 of the secondary winding of transformer T1 to resistor R.
1 and diode D2, forward biasing the emitter of transistor Q1 with respect to its base. Thereby, the current surge containing voltage pulses across the secondary winding of transformer T1 is transferred to winding L
Flows through 1.

Capacitor C2 connects the tank circuit with windings L2 and L3 and capacitors C1 and C3 from 5 to
It is chosen to tune to a convenient frequency such as 15KHZ. Thus, the first damped vibration at that frequency is set up in the secondary circuit. The polarities of the primary and secondary windings of transformer T1 are selected such that as the current through winding L1 increases, the top terminal of low voltage section L3 becomes negative, biasing transistor Q1 into conduction. .

When the top terminal of winding L3 subsequently goes positive, it cuts off transistor Q1. Winding L
The rapidly decreasing current in the secondary winding induces a regenerative component in the secondary winding, so that energy is transferred to the secondary winding to support the oscillations of both half cycles of the secondary voltage waveform.

When the voltage at the top terminal of winding L2 becomes higher than the top terminal of capacitor C3, diode D1 conducts current to charge capacitor C3. This clips the positive half cycle of the waveform on the transformer secondary, but leaves the negative half cycle unaffected.
This causes capacitor C1 to asymmetrically charge to a voltage of the polarity shown, cutting off transistor Q1 unless it is opposed and weakened by a corresponding negative voltage induced across winding L3. generates a voltage.

When capacitor C3 is charged to the desired voltage, lamp K2 is discharged and current flows through resistors R3 and R4. The voltage increase occurring across resistor R4 is not passed to the input terminal of multivibrator 7. The reason is that the transition does not take place in the direction passed by gate 8.

The device now connects capacitor C5 and resistor R6
The timing circuit containing the Schmitt Trigger 1
Push button S1 before lowering the output of 0 to a low potential.
If exposure is performed by pressing , it is ready for exposure. If exposure does not take place within this time limit, the low potential output of the Schmitt trigger 10 triggers the multivibrator 7 to reset the flip-flop 6.

When flip-flop 6 is reset, transistor Q2 is turned on, preventing transistor Q1 from being turned on when the top terminal of winding L3 becomes negative with respect to the bottom terminal.
This suppresses vibrations in the secondary circuit since no energy is supplied.

Capacitor C1 gradually charges through the emitter-collector path of transistor Q2 and resistor R1 until its voltage rises to a value at which no current flows through transistor Q2. This charge is gradually dissipated through the various reverse bias junctions of the circuit over a period of one week.

Capacitor C3 temporarily maintains a charged state. In this way, if the photographer decides to prepare to take a picture and presses the pushbutton S2 again, the preparation lamp K
2 will light up sooner than it originally did by a time that depends on the amount of charge remaining on capacitor C3. Of course, this charge will eventually dissipate due to capacitor internal leakage and other minor leakage effects.

Once the preparation lamp is on, the photographer can take an exposure by pressing button S1 before the reset operation time described above has expired. This causes the synchronization switch contact S3 to close at the correct time. When switch S3 closes, a ground level trigger pulse is applied to the connection between capacitor C4 and resistor R5.

Capacitor C4 discharges rapidly to generate a pulse across the primary winding L5 of pulse transformer T2 and to switch capacitor C3 into lamp K for the purpose described above.
1 to generate a flash.
The lamp K2 is then extinguished and the current flowing through the resistor R4 is interrupted. The drop voltage transition thus developed across resistor R4 is applied to gate 8 to trigger one-shot multivibrator 7, causing flip-flop 6 to reset. This turns on transistor Q2 and stops the voltage converter from oscillating in the manner described above. Following such a flash, once capacitor C3 is essentially completely discharged, a complete cycle time is required before the next exposure is possible.

Figure 3 shows the name of the invention ``Reflex Camera'' by Edwir H.Land, Igor Blinow and
Organized around an automatic single lens reflex camera as illustrated and described in U.S. Pat. No. 3,714,879 filed February 6, 1973 by Vaito K. 1 shows a modification of the present invention. In fact, the camera described in conjunction with FIGS. 3-5 may be identical to that shown and described in the above-mentioned patent, the entirety of which is incorporated herein by reference except for the variations described. .

From FIG. 3, camera 20, shown and described in detail in the above patent, is a fully automatic single lens reflex that folds into a thin compact form. This is shown in the assembled position in FIG. At that location, when a cassette containing a film unit and battery is supplied, the camera responds to the touch of a button and produces a photograph that is immediately ejected from the camera where it is developed.

As shown in FIG. 3, the housing 21 of the camera 20 has a lower portion 22 enlarged relative to the shape and size of the housing in the above patent;
This is adapted to house portions of the electronic flash equipment. As shown in Figure 3, there is a battery in the cassette 35 in the loading position of the camera 20.
This provides power for the film advance motor and exposure cycle control within the camera. According to the invention, the battery is also adapted to power an electronic flash device. For this purpose, terminals 36 and 37 provided in the camera for contacting the batteries in cassette 35 are connected to an electronic flash device as shown. In order to reduce the thickness of the additional housing section 22 required to house some of the electronic components of the electronic flash device, the portion of the flash device that has the largest characteristic dimension has its major dimension equal to the major dimension of the camera in the folded state. They are specifically selected and arranged to lie in parallel planes. For this purpose, transformer T1
is made thin, flat, and small, and the charging capacitor C
3 is preferably made of four tubular capacitors, of which capacitors C3A and C3
B is shown by the dotted line in Figure 3, so
The thickness of the camera does not increase significantly, and the main dimensions of the camera do not need to be changed.

The components of the electronic flash device located in the housing part 22 are connected by cables 23 to other components of the flash device. Cable 23 is connected to a reflector 24 . For this purpose, the cable 23 is connected to the housing 22 by a conventional removable plug 25 and to the reflector 24 by a conventional removable plug 26.
connected to.

The preparation lamp K2 and the pushbutton S2 are arranged on the reflector device 24 as in the previous embodiment. The illustrated positions merely illustrate the functional combination of these components and the reflector housing. Preferably, the preparation lamp K2 should be replaced by the folding viewfinder 3.
It is desirable to be behind the reflector 24 as seen in the upright position of 2. Pushbutton S2 is most conveniently placed on the right side of the reflector housing rather than the left side as shown.

Comparing FIGS. 3 and 4, the reflector 24 includes a blade 28 that fits into an accessory socket 40 in the lens board and shutter housing 27 originally designed to receive a flash bar. Basically, the blade 28 made of insulating material has at least two conductive segments 29.
and 30, which are engaged with corresponding contacts in the camera socket as shown.

As seen in FIG. 3, the enlarged lower portion 22 of the housing 21 of the camera 20 terminates at its forward end, which does not reach the hinged bed portion 33.
This causes the bed 33 to swing down so that the user can insert or remove the cassette 35 from the camera.

Referring now to FIG. 5, the relative positions of the components of the electronic flash device and its control system are shown. The components in camera 20 are enclosed in the large dotted block on the left side of FIG. 5 and are shown for connection to a battery (B) in cassette 35 on the left side of FIG.

With noted exceptions, the circuit of FIG. 5 is the same as the circuit of FIG. 2, and corresponding parts have been given corresponding symbols. The slight modifications described were made to adapt the circuit to the respective placement of the desired components to make it compatible with the Polaroid SX-70 land camera and to fit the flash device as described herein. This is illustrated by the specific embodiment shown in the above patent when modified as follows.
For purposes of the present invention, exposure control device 140 may take the particular form used in the Polaroid SX-70 land camera. Lens board 2 in Figure 3
The shutter button S1A on the front of the Polaroid SX-70 is modified in the ways described herein.
Equivalent to the shutter button on a land camera.

The exposure control device provides photoelectrically determined exposure. The switch S3A incorporates a device for changing the operating mode of the camera so that the conversion takes place between ambient light conditions and a flash mode of operation in which the aperture is selected according to the focal length of the camera. When the opening is opened, it is closed. For this purpose, a socket 40 in the lens board 27 of FIG. 3 into which the blade 28 of the reflector 24 is inserted has a pair of terminals 40 which are bridged by contacts 29 when the blade 28 is inserted into the camera. There are 41. When contacts 40 and 41 are bridged, the exposure control operates in the flash mode of operation described above.

Switch S3A in FIG. 5 is connected between the (B+) battery terminal and another terminal 42 in the camera's flash socket, which terminal 30 of blade 28 is adapted to contact. Thus, when switch S3A is momentarily closed to initiate a flash exposure, battery voltage is applied to terminal 30.

The components of the circuit of FIG. 2 included in the camera of the circuit of FIG. 5 include transistor Q3, capacitor C5, resistor R6, and Schmitt trigger 1.
There is a timing circuit with a zero that turns off the charging circuit if no photo is taken within the predetermined time mentioned above. One button to start the charging cycle
Shot multivibrator 15, flip
One-shot multivibrator 9, gate 8, one-shot multivibrator 7, and flip-flop 6 ensure that flop 6 is reset, a voltage converter with transformer T1 and transistor Q1, and a capacitor. C1, resistor R2, transistor Q4, Zener diode D3, transistor Q2, diode D2 and resistor R1, all included in the camera, as well as a switching circuit.
All of these work in the same way as described above. Capacitor C2 and rectifier diode D1 are composed of four small capacitors C3A, C3B, C3C,
It is located inside the camera as well as the charging capacitor C3, which is composed of C3D.

The preparation lamp K2 is placed in the reflector. Therefore, the circuit that turns off the charging circuit when the flash is fired is modified somewhat. For this purpose, capacitor C80 at gate 8 is connected directly to the high voltage lead at the junction of capacitor C3 and diode D1. Capacitor C80 is selected to have a higher line voltage than the corresponding capacitor C8 in the circuit of FIG. 2 because it will experience a larger voltage.

The input terminal of the one-shot multivibrator 15 is connected to one connector terminal 4 by a lead 45 attached to the cable 23 to a corresponding terminal 46 in the socket of the reflector 24.
Connected to 4. Similarly, the upper side of the capacitor C3 is connected by a lead 48 of the cable 23 to a terminal 47 which is connected to a terminal 49 of the reflector 24. The underside of capacitor C3 is connected to cable 23 to reflector 24 by lead 51 of cable 23.
It is connected to a terminal 50 which is connected to a terminal 52 located at. It will be apparent that when the devices are connected together, terminal 52 will be at battery voltage (B+).

A charging start pushbutton S2 is attached to the reflector 24 and connected to both ends of the terminals 46 and 52.
Therefore, when pushbutton S2 is pressed momentarily, it creates a rising transition that triggers the one-shot multivibrator 15 as described above.

The preparation lamp K2 is connected between terminals 49 and 52 in series with one current limiting resistor R10. As mentioned above, the ready lamp K2 produces a visual indication when the capacitor C3 is charged enough to produce the correct exposure, but the ready lamp circuit serves no other function in this embodiment of the invention.

When the discharge tube K1 is triggered, the capacitor C
Terminal 49 so as to be excited by the current from 3
and 52. The trigger circuit with transformer T2, capacitor C4, and resistor R5 is the same as above. The trigger input signal is asserted when switch S3A is closed, shunting charged capacitor C4 through input winding L5 of transformer T2.

The operation of the apparatus of FIG. 5 is essentially the same as described above. When battery B is first connected to the camera terminals, for example by placing cassette 35 into the camera as shown in FIG. 3, one shot multivibrator 9 is triggered. At the trailing edge of the pulse generated by multivibrator 9, gate 8 triggers one-shot multivibrator 7 to reset flip-flop 6. The device then presses the pushbutton S
When pushbutton S2 is pressed, multivibrator 15 generates its output pulse to set flip-flop 6 and charge capacitor C3 as described above. .

When capacitor C3 is charged, ready lamp K
2 is added. Thereafter, when shutter button S1A is closed, the exposure control device closes switch S3A at an appropriate time to discharge capacitor C4 through the primary winding of the pulse transformer, thus triggering discharge tube K1 to provide a flash exposure. will be carried out. The falling voltage transition across capacitor C3 activates gate 8 through capacitor C80, triggering one-shot multivibrator 7 and resetting flip-flop 6. The device then remains in its stationary state until shutter button S2 is pressed again.

According to another embodiment of the invention, a switch S2 is attached to the camera 20. This can be done by simply attaching two leads to the cable 23. The position of switch S2 is camera housing 2
2 or on the lens board 27.

Although the invention has been described in detail with particular embodiments, many modifications and variations will occur to those skilled in the art upon reading this description and are clearly possible within the scope of the invention.

[Brief explanation of the drawing]

1 is a partial cross-sectional and exploded elevational view of a camera equipped with a flash device according to the invention, and FIG. 2 is a block and wiring diagram of a suitable control device for use in the device of FIG. and the third
The figure is an elevational view of another camera with a flash device according to another embodiment of the invention;
4 is a perspective view of the reflector device shown attached to the camera of FIG. 3, and FIG. 5 is a wiring diagram of the flash device of FIGS. 3 and 4. FIG. 1, 20 - camera, 2, 5 - lens, 3 - strobe lens, 4, 24 - reflector, 6 - flip-flop, 7, 9, 15 - one shot.
Multiviprator, 8-or gate, 10-
Schmitt trigger, 14,140-exposure control device, 21,22,27-housing, 23-cable, 25,26-plug, 27-lens board, 28-blade, 29,30-conducting segment, 32-finder, 33-bed, 35-cassette, 40, 41, 42-socket, 45,4
8,51-Reed, 36,37,40,41,4
2, 44, 46, 47, 49, 50, 52, S,
R-terminal, K1-flash discharge tube, K2-ready lamp, S1, S2, S3, S1A, S3A-push button switch, B-battery, T1-transformer, T
2-Transformer, L1, L5-Primary winding, L2, L
3, L4-secondary winding, Q1, Q2, Q3, Q4-
Transistors, C1-C8, C80, C3A-C
3D-capacitor, R1~R7-resistor, D1~
D4 - diode.

Claims (1)

[Claims] 1. a triggerable discharge tube; a charging capacitor; and a device for discharging the capacitor to produce flash illumination when the capacitor is charged to a predetermined level and the discharge tube is triggered;
a charging circuit connected to the capacitor and a power source and operating in response to an input signal to charge the capacitor; a manual device generating a starting signal by manual operation; and selectively switching between a set state and a reset state. , a bistable circuit generating the input signal for operating the charging circuit in the set state;
means for placing the bistable circuit in a set state in response to the start signal; means for placing the bistable circuit in a reset state in response to discharging of the capacitor through the discharge tube; and a timing circuit that resets the bistable circuit when the capacitor is not discharged within a predetermined time limit after being charged.