JPS5925359B2 - automatic dimming flash device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a series-controlled automatic flash device and a flash photography device using the same.

In some conventional flash devices of this type, when charging of a main capacitor that stores energy for flash light emission is completed, a ready light is turned on to indicate completion of light emission preparation.

Therefore, the user generally releases the camera shutter in accordance with this display, that is, when the ready light turns on. At this time, the camera shutter speed is 1/60
The flash synchronization time, such as sec, is set. When the camera's shutter is released after the ready light is turned on, the charge in the main capacitor is discharged and consumed in accordance with the amount of flash light emitted, and its charging voltage decreases, so the ready light is turned off. Therefore, the user stops taking pictures until the ready light is turned on again and preparation for emitting light is completed. However, the energy stored in the main capacitor of a series-controlled automatic flash device is consumed only as much as is necessary depending on the distance and reflectance of the subject, so even if the ready light is off, the energy stored in the main capacitor is In many cases, it is possible to take flash photography again due to the residual energy in the main capacitor.

A person skilled in flash photography would be able to judge this empirically based on the various conditions of the subject, but it would be difficult for someone inexperienced to make this judgment. Therefore, an inexperienced user may miss the opportunity to take a photo until the ready light turns on.

In addition, a flash photography device V is equipped with this series-controlled automatic light adjustment flash device in a camera that automatically controls the shutter time.
C$? Some devices set the shutter time to the above-mentioned flash synchronization time by detecting the lighting of the ready light.

Even if such a flash photography device Vc is used, once the flash photography device is used, flash photography cannot be performed until the ready light is turned on, resulting in the inconvenience of missing a shot. SUMMARY OF THE INVENTION An object of the present invention is to provide a series-controlled automatic flash control flash device that displays this display when the remaining energy stored in the main capacitor after firing a flash is sufficient to fire another flash, allowing flash photography to be taken immediately. It's about doing.

Another object of the present invention is to provide a flash photography device which displays this display if the remaining energy stored in the main capacitor after firing the flash is sufficient for another flash, and at this time controls the shutter time to a value suitable for flash photography. Our goal is to provide the following.

In order to indicate whether re-flash emission is possible or not, the following comparison is generally made.

This method compares (energy consumed by light emission) and (residual accumulated energy in the main capacitor after light emission), and determines and displays whether the remaining accumulated energy is sufficient for consumption in another cycle. However, in the present invention, (1/2 of the energy stored in the main capacitor before light emission) is compared with (the residual energy stored in the main capacitor after light emission). This is shown mathematically. If the stored energy of the main capacitor before light emission is E and the consumed energy is ΔE, then the residual stored energy is (E-ΔE). Therefore, in the general method, (E-△E)〉△E...Re-emission is possible (E-△E); △E...Re-emission is not possible; in the present invention, (E-△E)> -E... Re-emission possible (E-△E) -E... Re-emission not possible The validity of the criteria for determining the present invention is shown below.

(E-△E)>-E means -E>△E.

Therefore, (E-△E)〉-E〉△E, indicating that the residual stored energy is ultimately larger than the consumed energy. Similarly, (E-ΔE)-E means -E<ΔE.
Therefore, (E-ΔE) -E<ΔE, indicating that the residual stored energy is smaller than the consumed energy. This is because it is extremely advantageous in a specific circuit configuration to compare the residual stored energy with 1/2 of the stored energy before light emission instead of directly comparing it with the consumed energy as in the present invention.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 shows a circuit diagram of a conventional series-controlled automatic dimming flash device.

When the power switch S1 is turned on, the main capacitor Cm is charged by the power source E and stores electrical energy for flashlight emission, and the commutation capacitor C2 is also charged via resistors 4 and 5 to produce a flashlight as described below. Accumulates electrical energy for stopping light emission. Now, after the charging of capacitors Cm and c2 is completed, the synchro switch S, which is linked to the camera release, is activated.
2 is turned on, a trigger current flows from the trigger circuit 1 to the primary winding P of the trigger coil 2, and as a result, a high voltage is generated in the secondary winding S.

Further, when the synchro switch S2 is turned on, the trigger circuit 1 generates a trigger pulse to turn on the SCR (silicon controlled rectifier) D1. Therefore, since the main capacitor Cm, the discharge tube FT, and SCRDl form a closed circuit, the discharge tube FT emits flash light by being supplied with electrical energy from the main capacitor Cm. This flash light emission illuminates the subject, and a portion is reflected by the subject and passes through the light receiving element D,
incident on .

The integrating circuit 3 temporally integrates the output of the light receiving element D2, and when the integrated value reaches a predetermined value, generates a trigger pulse to turn on the SCRD 3. Therefore, SCRD3 is turned on, and commutating capacitor C2 is connected between the anode and cathode of SCRD, which is in the on state. This allows the SC
Since RDl is in a reverse bias state, it is turned off, and as a result, the discharge tube FT stops emitting flash light. In this way, the amount of flash light emitted is controlled according to the brightness of the subject, that is, automatic light adjustment is performed. The stored energy of the main capacitor Cm is the corresponding residual stored energy E2=-CV22 connected in series with the discharge tube FT.
]N↓'2(REi!1V1) The corresponding charging voltage of the main capacitor is 1/J.Next, the operation will be explained.

When power switch S is turned on, FFl is Q:H,Q
:L, A2, A, are on, A3, A4 are off. At this time, the first memory capacitor C,l causes V
c, tvcc. Second memory capacitor Cl2
is charged to the voltage at point a, that is, when A5 is turned on, and stores that voltage.

The input of A1 is the voltage at point b, that is, the → input is VCl! via the analog switch A2. 7Vce
, is applied.

At this time, if Rl3 and Rl4 are set so that

As a result, the LED is turned off. Now, when the charging of the main capacitor Cm progresses and charging is completed, the neon lamp NL lights up to display this fact.

At this time, LEDl remains off. Next, the synchro switch S is activated by the shutter release of the camera (not shown).
2 is turned from off to on, FFl becomes Q:L,Q
:H, and A2 and A are turned off and A3 and A4 are turned on.

At the same time, the flash light emission of the discharge tube is started and automatic light adjustment is performed as explained in FIG. At this time, the main capacitor C
The charging voltage of m will undergo a voltage drop (ΔVCC2) equivalent to the energy required for flash light emission. Therefore, A1
The e input of is ), and the θ input is the storage voltage of the second memory capacitor C, l, that is.

The neon lamp NL is turned off because the main capacitor is discharging.

Then, after the flash fires, D1
1) Issho▼llll - -! 14-. If the value is U - Issoku τ - △VCC2), the output of A1 will be higher than the e input of A1, so the output of A1 will be L, and as a result, the LED l will not light up and the next flash photography will not be possible. Display something.

On the other hand, if after the flash is emitted, the e input of A1 becomes higher than the e input (the output of FCAl becomes H, and as a result, L
ED, lights up to indicate that flash photography can be performed immediately even though the neon lamp NL is off.

To describe the next operation, since A3 and A4 are on, the first memory capacitor C, ., VCl=1 pin 12, .
．． 、． - Charged to (VCC2 - ΔCC2).

When this LED lights up, the next release is performed and the synchro switch S2 is turned on from off, the FF and Q
:H, Q:L, and A2, A, are on, A,,A
4 becomes of.

At the same time, the discharge tube emits a flash of light and automatic dimming is performed.
At this time, the charging voltage of the main capacitor (VCC2-
ΔVCC2) receives a voltage drop (ΔVcc2') equivalent to the energy required for flash light emission. Therefore, the A,Ol input becomes 几14-1113, and the θ input is the charging voltage of the first memory capacitor C,l, that is, Rl2n. LT) ・(VCC2-△VCC2).

And after the flash fires, 1V1! - When ▲VlZ is reached, LEDl goes out, indicating that the next flash photography is not possible.

On the other hand, if Vll-breath-11 after the flash is emitted, the e input of A is higher than the θ input, so
The output of A becomes H, and as a result, LED lights up to indicate that flash light emission is possible.

Thereafter, the same operation is repeated every time the synchro switch S2 turns ON, and flash photography can be performed continuously as long as the LED is lit. To be more specific with numerical values, the criteria for judgment are, as mentioned above, whether it is 1/V or 1 VCC2-△VCC2?7 CC2.

R,,,R,2,Rl3 and Rl4 corresponding to this are:
Also, from the conditions of the initial setting value,
No Ih) Rent Tn? If R,4/Rl3+Rl4=1/20 to satisfy the condition of O, then R,2/
R, ,+Rl2=1/20VΣ.

In other words, point a may be at a potential of 1/VΣ of point b. Next, assuming that the stored energy of the main capacitor at the charging voltage is 100 and the energy consumed by one light emission is 30, the judgment process according to the present invention is shown in the following table.

Main Conde Memo Gorge. Comparative voltage of the residual storage capacitor of the re-emitting sensor Cosmetic energy pressure (CC2/Sr2) In summary, the voltage at point b after the flash is emitted is 1/V of the voltage at point b. The voltage at point a before the divided flash is compared by A1, and if the manual power e is higher than the input e, it is displayed that dimming cannot be performed even if the flash is emitted by LEDl,
If the θ input is lower than the 1 input, it is displayed that the light can be dimmed even if the flash continues to be emitted.

It is also possible to lock the shutter release by detecting that the LED lights are turned off. In the embodiment described above, when the LED goes out, charging of the main capacitor is waited for, but at this time, before the charging of the main capacitor is completed (before the neon lamp NL is lit). The LED lights up.

This means that the first or second memory capacitor is
This occurs because the voltage at point a before the light is turned off is stored. Therefore, if a photographer performs flash photography in accordance with the lighting of LEDl, there may be cases where light control becomes impossible because the charging voltage of the main capacitor is insufficient. Another embodiment of the present invention, shown in FIG. 3, attempts to overcome this drawback. In this embodiment, the display means for indicating whether or not the residual energy of the main capacitor remains sufficient to enable re-emission is provided with a flip-flop FF2 consisting of a light emitting diode LED2 and a NAND gate GlG2.

The reset input terminal of flip-flop FF2 is connected to the output of comparator A. Transistor Q1 is connected to the power supply CC which indicates the charging voltage of the main capacitor via the resistor r.
2VC is connected. The gate of transistor Q1 is
It is connected to the neon lamp NL for indicating the completion of charging of the main capacitor. The collector of transistor Q1 is buffer G.
,. It is connected to the set terminal of flip-flop FF2 via. The Q output of the flip-flop FF2 is connected via a resistor R6 to a light emitting diode LED2 for displaying the residual energy of the main capacitor. In this embodiment, once this diode LED2 is turned off to indicate a decrease in the remaining energy stored in the main capacitor, this state is maintained by the flip-flop FF2. After that, C charging of the main capacitor is completed and the neon lamp NL
When the light is turned on, the transistor Q sets the flip-flop FF2 via the buffer GlO to turn on the light emitting diode LED2 again. The other configurations are the same as the embodiment shown in the second figure, and the same parts are given the same reference numerals j. Next, the operation of this embodiment will be explained.

Closing switch S energizes the circuit shown. The flip-flop FF may be in either the set or reset state, but it is assumed that it is in the set state.
Its Q and 'Q outputs are H and L. Analog switches A2 and A5 are 0N, and analog switch A3
, A4 is 0FF. Capacitor Cll applies the same voltage as Cc to the inverting input of comparator A1 via switch A2. Record the voltage C at point a corresponding to the charging voltage VCC2 of the main capacitor to the capacitor C,2.

On the other hand, the voltage at point b, that is, the charge of the main capacitor, is applied to the non-inverting input of the comparator A1. As in the embodiment shown in the second figure, before the charging of the main capacitor is completed, the voltage Vcc is higher than the voltage at point b, so the output of the comparator A1 becomes L. Furthermore, before the charging of the main capacitor is completed, the voltage CC2 applied to the neon tube NLVC via the resistor R4 is low, so the neon tube NL is turned off and the transistor Q1 is also turned off. Therefore, the resistance r
An H level voltage is applied to flip-flop FF2VC via buffers G and O to set it to the set state.
Therefore, the Q output of the flip-flop FF2 becomes L, and the light emitting diode LED2 is turned off. Next, when charging of the main capacitor is completed, the voltage at point b becomes higher than voltage VCCl, and the output of comparator A1 becomes H. On the other hand, the neon tube NL is turned on via the resistor R4, and the transistor Q1 is also turned ON. For this reason, the buffer GlO
gives an L level voltage to flip-flop FF2. Flip-flop FF2 is set and its Q output is H.
As a result, the light emitting diode LED2 lights up. Next, when the shutter is released, the synchro switch S2 is closed, flash light emission is started, the main capacitor is discharged, and the neon tube NL is turned off.

Further, by closing the synchro switch S2, the state of the flip-flop FF is reversed, and the Q and Q outputs become L and H. Therefore, switches A3 and A4 become ON, and switches Ai and A become OFF. Here, capacitor C,
l is the point a after the main capacitor is discharged.
Voltage of \ (..
Charge UT, I (VCC2-△Vcc2)) to ＼-.

The capacitor Cl2 outputs the voltage 67''Σ曾, 1・VOC2) at point a, which was stored before the main capacitor was discharged, to the comparator A1.
give to Comparator A1 compares this voltage with the voltage at point b after discharge. Then, as in the embodiment shown in the second figure, if the residual energy of the main capacitor remains to the extent that it can emit light again, the voltage at point b is
fCnd becomes higher than the intended voltage, and comparator A1 continues to generate an H level voltage. Next, the shutter is released, the synchro switch S2 is closed, the main capacitor is discharged for the second time, the state of the flip-flop FF is reversed, and the Q and Q outputs become H and L.
Switches A2, A, become 0N, and switches A3, A4
becomes 0FF. Comparator A, capacitor C,
, compares the voltage at point a stored after the first main capacitor discharge with the voltage at point b after the second discharge. Thereafter, the same cycle is repeated as long as the residual energy in the main capacitor remains sufficient to enable re-emission. On the other hand, if the residual energy has decreased to such an extent that re-emission is impossible,
As in the embodiment shown in the second diagram, the voltage at point b is lower than the voltage at point a stored in capacitor Cll or C,2 before the previous light emission, so the output of comparator A becomes L level. Also, since the main capacitor is not fully charged,
The neon tube NL goes out, the transistor Q becomes 0FF, and the buffer GlO gives an H level voltage to the flip-flop FF2. For this reason, flip-flop FF2
is set, its Q output becomes L, and the light emitting diode LED2 turns off. Once light emitting diode 5 iodine LED
After FF2 is turned off, the state is maintained as follows: Flipflow*÷FF2VC until charging of the main capacitor is completed. That is, after the light emitting diode LED2 goes out, the main capacitor is charged and the potential at point b becomes higher than the voltage stored in the capacitors C,l or C,2, and the output of the comparator A becomes HVC inverted. do. However, before charging is completed, the neon tube NL is off, so the buffers G and O send the H level output to the flip-flop F.
F2VC. giving. Therefore, the flip-flop F
The Q output of F2 continues to be L, and the light emitting diode LE
D2 remains off. Next, when charging is completed, the neon tube NL lights up, and the buffer GlO begins to provide a flip-flop FF2VCL level output. Therefore, the flip-flop FF2 is reset by the H level output of the comparator A1, its Q output becomes H, and the light emitting diode LED2 lights up. Thereafter, the light emitting diode LED2 continues to light up as long as there is enough residual energy in the main capacitor to enable re-emission. The third above
The operation of the illustrated embodiment is summarized in the following table.

Ru.

Block 20 includes the circuitry of FIG. camera side 2
After the shutter release of the first circuit lζ camera is performed, the reflected object light is metered by the shutter curtain and/or the film surface, and the exposure time is automatically controlled. So-called TTL direct metering shutter seconds? Contains control circuit. The operation of the display light emitting diodes LED,l and LEDl2 of this embodiment will be described. The forward voltage drop of LED,2 is VLED,, the forward voltage drop of diode Dll is 3×F, and the forward voltage drop of LED,2 is VLED,,.
When LEOl2, VLEDl,〉3F>VLED
Select a diode that provides l2. This condition is, for example, LED, , Cap light emitting diode, LED,
2 can be replaced with a CaAsP light emitting diode or the like.
When the power switch S is turned on, if the strobe is fully charged, the neon lamp NL will be lit, so the transistor Q
2, Q22 and Q24 are 0N1. Transistor Q23 is turned 0FF, LED11 and LED12 are turned on, and transistor Q18 is turned ON. Next, when continuous shooting is possible without flash charging, transistors Q2, , Q23 and Q
24 is 0NJ transistor Q22 becomes 0FF, and the light emitting diode LED,, goes out due to the previous condition of VLED,,〉3F>VLEDl2, but the light emitting diode LED
l2 is lit and transistor Q,8 is 0NVC. Become. When the transistors Q and 8 are on, the shutter speed is fixed at, for example, 1/60 second in the &31 optical type shutter speed control circuit 21. Then, when the light emitting diode LED,2 goes out, the transistor Ql8 turns off and an automatic exposure control operation is started. That is, turning on and off the transistor Ql8 switches the camera operation to automatic exposure control operation or flash photography operation. This operation will be explained in detail below.

The trigger switches S and 4 are turned off in conjunction with the release operation, and turned on when the shutter charge is completed. Capacitor C,3 is connected in parallel with trigger switch S,4. The photoelectric conversion element 10 forms a series circuit with a capacitor Cl3 via a transistor Ql2. The resistor R2l forms a series circuit with the capacitor C,3 via the transistor Ql3. Capacitor C, 3, photoconductive element 10 and resistor R
The connection point with 2 and 2 is connected to one input terminal (d) of the comparator A1-1. Variable resistor R22 is film sensitivity,
One voltage is generated corresponding to information such as the aperture value.

One of these voltages is connected to a field effect transistor (hereinafter referred to as FET).
is applied to the other input terminal (4) of the comparator A1-, via Ql4 (referred to as Ql4). At the connection point of the resistors R23 and R24, the other voltage having a constant value is generated to obtain the shutter speed for flash photography. This other voltage is also applied to the other power terminal (4) of comparator A,1, via FETQ, . The output of the comparator A1-1 controls the magnet Mg for locking the shutter trailing curtain. Transistors 3tQ, 6 are turned on and off by transistors Q, 8VC,
Their relationships are in opposite phases. Now, after attaching the flash device to the camera, when taking a picture using automatic exposure control, first turn off switches S and 3. This turns transistor Q,8 off and, as a result, transistor Ql6 turns on. By turning on transistors Q and 6, transistors Ql3 and FET Ql5 are turned off, respectively. On the other hand, since transistor Ql8 is off, transistor Ql, is turned on, and FET Ql4 is turned on.
turns on. Therefore, only one voltage is applied to the human power terminal (A) of the comparator A,1. On the other hand, since the trigger switch Sl4 is on before the release operation, the comparator A
The positive voltage of the power supply E2 is applied to the voltage at the input terminal (d) of the comparators A, 1-, 8, and as a result, the comparators A, 1-, output an L level signal. Therefore, the magnet Mg is energized and remains in a state in which the rear curtain of the shutter is locked. When a release operation is performed now, the trigger switch S, 4 is turned off at the same time as the leading shutter curtain starts running, so the capacitor C, 3 and the photoelectric conversion element 10 form an integrating circuit.

Further, the resistance value of the photoelectric conversion element 10 changes as it receives object light reflected from the front curtain of the shutter and/or the surface of the film being exposed. Therefore, the charging time constant of the capacitor Cl3 corresponds to the brightness of the subject. Now,
When capacitor Cl3 starts charging, comparators A,-,
An integrated voltage that gradually decreases from the positive voltage of the power source E2 is applied to the input terminal (c) of the power source E2. And comparator A1-,
When the voltages at both input terminals (4) and (→ of In this way, the automatic shutter speed control using TTL direct metering is completed.At this time, the synchro switch S, is turned on, but the power switch S,
is off, so block 5 does not operate. Therefore, no flash light is emitted. Next, to take flash photography, turn on switches S and 3.

When LEDll or LEDl2 lights up as a result,
Transistor Ql8 turns on. Transis 3tQ,
2, Q, 6 and FET Ql4 are turned off by turning on transistors Q and 8, respectively. When transistors Q, 6 are turned off, FET Q15 and transistors Q, 3 are turned on, respectively. Therefore, when the trigger switches S and 4 are turned off, the integrated voltage of the integrating circuit constituted by the capacitor Cl3 and the resistor R2l is applied to one input terminal (c) of the comparator A1-1, and A constant voltage determined by resistors R23 and R24 is applied to (4). That is, the time from when the trigger switches S and 4 are turned off until the magnet Mg is demagnetized, ie, the shutter time, is controlled to be constant regardless of the brightness of the subject, film sensitivity, and aperture value. This controlled shutter time is a value that the flash device can tune to, for example, 1/60 sec. If the program 20 indicates that continuous light emission is possible, as mentioned above, even if the LEDs are off, the LED 12 is on, so the transistors Q and 8 are on, and the transistors Q and 6 are off, so the program 21 is in a flash photography state. When LED,1 and LED,2 are both off, that is, when continuous light emission is not possible, transistor Q,8
is turned on, transistors Q and 6 are turned off, and the automatic exposure control operation described above is performed. Needless to say, during flash photography, when the synchro switch S2 is turned on, the flash device emits flash light to illuminate the subject, and when the amount of light reflected from it reaches a predetermined value, the flash light emission is stopped.

According to the present invention as described above, the residual energy stored in the main capacitor after the flash is emitted (under the same subject conditions)
The flash can be emitted immediately, reducing the chance of missing a shot.

Further, according to the present invention, if the remaining energy in the main capacitor after the flash is lit allows the light to be adjusted by firing the flash again under the same subject conditions, this display is made, and at this time, the shutter seconds are set to the flash. Since the shutter speed is controlled to a value suitable for photographing, errors in setting the shutter speed are eliminated, and the chances of missing a shutter start are reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional series-controlled automatic flash control device, and FIG. 2 is a circuit diagram of an automatic flash device according to the present invention that includes a device for determining whether re-flash emission is possible. , 3rd
This figure is a circuit diagram of a device that is an improved version of the device shown in FIG. 2, and FIG. FIG. 3 is a circuit diagram showing another embodiment of the device of FIG. 2; Explanation of the symbols of the main parts, R, , Rl2Cll in Fig. 2
LaCl29A29A3νA4tA59FFl...
・Means for generating the first voltage, R, 3, Rl4 in Fig. 2
...Means for generating a second voltage, A1 in Fig. 2
・・・・・・Means for comparison, R6, LEDl in Fig. 2
...Display means, Cl in Fig. 2, ...
1st memory, Cl2 in Fig. 2...Second memory, FF in Fig. 2,...control means, Q in Fig. 3
l, G, O, FF2...Means for prohibiting display;
Dll in FIG. 4: a diode for switching, LEDll in FIG. 4: a first light emitting diode, LEDl2 in FIG. 4: a second light emitting diode.

Claims (1)

[Scope of Claims] 1. In a series-controlled automatic light control device, means for generating a first voltage corresponding to the energy stored in the main capacitor before the flash is emitted, and corresponding to the residual energy stored in the main capacitor after the flash is emitted. means for generating a second voltage that causes the flash to emit, means for determining whether the flash can be emitted again for the same subject state with the residual stored energy based on the first and second voltages after the flash has been emitted, and the result of the determination. and means for displaying. 2. In the series-controlled automatic flash control flash device according to claim 1, the first voltage is a voltage corresponding to half of the light emission energy corresponding to the charging voltage of the main capacitor before flash emission. A device characterized by: 3. In the series-controlled automatic dimming flash device according to claim 2, the means for generating the first voltage includes a first and a second memory, and the first and second memories are connected to each other. whose operation is alternately switched between a period of storing a voltage corresponding to half of the luminous energy corresponding to the charging voltage of the main capacitor and a period of applying the stored voltage to the comparison means, and The operating periods of the memories are switched by the control means to be complementary, so that after the flash is emitted, a voltage corresponding to half of the emitted light energy corresponding to the charging voltage of the main capacitor before the flash is emitted during the comparison. Apparatus, characterized in that it generates a first voltage applied to the means.