JPH0658484B2 - Electronic flash device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic flash device suitable for use in combination with a camera having a focal plane shutter.

When the conventional electronic flash device is used in a camera with a focal plane shutter, exposure unevenness occurs unless the flash discharge tube finishes emitting light while the shutter is fully opened. In order to prevent this, it is necessary to manually set the shutter speed to a speed lower than the expected time when it is considered that the unevenness does not occur. However, at this time, there was a problem that the shutter speed was erroneously set due to carelessness. In order to solve this, there is one that detects the power-on of the electronic flash device and the completion of charging of the capacitor, transmits the detection signal to the camera, and automatically sets the shutter speed at the time when exposure unevenness does not occur. However, the same detection signal is generated in both a small atomic flash device with a relatively short light emission time and a larger electronic flash device with a long light emission time. It has a drawback in that it is automatically set to the desired shutter speed, and the stop-motion effect of the electronic flash device having a short light emission time cannot be fully utilized.

On the other hand, there has been devised a method of preventing uneven exposure by forcibly stopping the light emission of the flash discharge tube by an electric signal for starting the rear curtain running of the focal plane electric shutter. In this case, the total amount of light of the electronic flash device is not used, and when the exposure is insufficient due to the emission being stopped midway, it is not possible to know it before shooting, and it is only after the shooting that the exposure is insufficient. It could only be displayed. As described above, when the total amount of light is not available, there is a drawback that the range of automatic light control photography is narrowed by an unpredictable amount on the long distance side.

As another method, an electric signal for stopping the light emission of the automatic light control electronic flash device can be transmitted to the camera, and the closing operation of the shutter rear curtain can be started by the signal.
However, it takes at least 2-3 ms from the start of the trailing curtain to the actual closing of the screen, so if this is the case, the shutter speed will be very long, and it will be easily affected by light sources other than flash. You will end up shooting photos that are blurred or have unnatural colors.

Therefore, a method of outputting a signal prior to the light emission stop signal of the flash discharge tube in anticipation of the rise time of the rear curtain is also considered, but in many electronic flash devices, the light emission time is short and it is only a few ms in total. Is not an effective system, because even if it sends a signal to the rear curtain system immediately after the light emission starts, the shutter speed becomes longer than the necessary and sufficient shutter time.

The present invention displays the information on the maximum flash emission time within a range where the flash emission time does not cause unevenness of exposure for the shutter speed set automatically or manually, without failing to capture the intention of the photographer without photographing. An object of the present invention is to provide a flash device that realizes a camera system that can be sufficiently reflected in a shooting result.

The present invention relates to an electronic flash device mountable on a camera, comprising a focal plane shutter and shutter speed signal generating means for generating a signal according to a set shutter speed, wherein the shutter speed signal from the shutter speed signal generating means is used. And a warning means for warning when the shutter fully open time according to the shutter speed signal is shorter than the maximum flash light emission time of the electronic flash device.

In the case of a flash device in which the maximum flash emission time is fixed, it is warned beforehand that the shutter fully open time is shorter than the maximum flash emission time before shooting, and the shutter speed of the camera is synchronized with the maximum flash emission time. A camera system that can set the highest possible shutter speed, and in the case of a flash device that can adjust the maximum flash time, a camera system that can set the maximum flash time that can be synchronized at the set shutter speed. It is an electronic flash device that enables

The fastest shutter speed that can be tuned at a certain time is the fastest shutter speed at which the aperture is fully opened at least during that time. Further, the longest maximum flashing time that can be tuned at the set shutter speed means at least the longest flashing time that does not exceed the full opening time of the aperture.

FIG. 1 is a diagram for explaining the present invention. This figure shows
A camera body 1 and an electronic flash device 2 attachable thereto are generally shown. The electronic flash device 2 has a mounting foot 3 and a camera body 1.
Is provided with a mounting seat 4, and the mounting foot 3 can be connected to the mounting seat 4. The camera body 1 is further provided with a shutter dial 5, and the shutter speed set here is indicated by the index 6. Further, the signal indicating the set shutter speed is transmitted from the camera body 1 to the electronic flash device 2 through one of the terminals of the terminal group 7 provided on the lower surface of the mounting foot 3.

FIG. 2 shows a terminal group 7 under the mounting foot 3 of the electronic flash device 2.
An example will be shown.

The structure of the terminal group 7 is as follows. That is, the ready light terminal u ₁ , the shutter speed input terminal v ₁ , the sync terminal
It consists of x ₁ , a light emission stop signal input terminal y ₁ , and a ground terminal g ₁ .
Of course, the mounting seat 4 of the camera 1 is also provided with the terminals 8 that can contact the terminal group 7.

Here, the shutter speed signal will be described with reference to FIG. The shutter speed set by the camera body 1 is a running curve b of the leading curtain (not shown) and a running curve c of the trailing curtain (not shown).
Is represented by the time difference t _s . At this shutter speed t _s ,
The time tf that can be used for the light emission of the electronic flash device 2 is as follows.

_{tf = t s -t m -t d} -α where t _m curtain run time required to travel the front curtain of Apachiyua A, t _d is synchro X contact from the time the front curtain is fully opened Apachiyua A Shows the time until is turned on. α is a margin time set in consideration of variations in the shutter speed t _s and variations in the X contact timing t _d .

Of the above times, t _m , t _d , and α differ depending on the type of camera, such as vertical running, horizontal running, rotary, and the structure of the synchro contacts. Become. Under these circumstances, the camera body 1 outputs to the electronic flash device 2 a signal in an amount corresponding to the length of the time t _{f that} can be used for the electronic flash device 2 to emit light. The electronic flash device 2 inputs this signal and compares the time t _f with the light emission time of the electronic flash device by, for example, a built-in comparison circuit. Then, when the time t _f is shorter than the light emission time, a warning is issued.

The comparison circuit and the warning method will be described in detail later.

Here, the emission characteristics of the general electronic flash device 2 tend to concentrate the emission amount in the first half as shown in the upper diagram of FIG. The horizontal axis t represents time, and the vertical axis I represents emission intensity. Since the light amount of the portion minus the tail of the emission end of life at this time graph is relatively small, considered as t _f 'in Figure instead total light emission time t _f the electronic flash device Contact emission time compared to the time t _f You can also

FIG. 4 shows the back surface of the electronic flash device 14 that can be mounted on the camera body 1 of the embodiment. Flash intensity selector 15
When FULL indicates, the total amount of light can be used, when 1/2 indicates, 50% can be used, and when 1/4 indicates, 25% can be used. It should be noted that both the electronic flash device 2 of FIG. 1 and the electronic flash device 14 of this figure can be applied to the present invention regardless of the presence or absence of the automatic light control function.

This electronic flash device 14 is used for the shutter speed from the camera body 1.
A signal representing t _f is accepted and the shutter speed t _f is compared with the light emission time selected by the selector 15. And the light-emitting time at the time longer than t _f lamp 16 to warn flashing. At this time, the shutter dial 1 of the camera body 1
5 may be operated to switch to a longer shutter speed, or when the amount of light is sufficient for the subject, the selector 15 may be switched to 1/2 or 1/4 to reduce the flash time.

FIG. 5 shows the light emission characteristics. That is, FULL, 1/2, and 1/4
The light emission characteristics at the time of each light emission are shown by d, g, and e, respectively. Then, for example, when the shutter speed manually set, the selector 15 is operated to increase the light emission time, and when the time exceeds the shutter speed set by the camera, the lamp 16 blinks. And warn. When the shutter dial 5 is operated to make the shutter speed longer than the maximum flash emission time selected by operating the selector 15, the lamp 16 is turned off. At this time, even if the shutter speed is short up to the lengths of t _f1 , t _f2 , and t _f3 , exposure unevenness does not occur.

In order to make the total light emission time shorter in the FULL light emission mode, the light emission may be stopped in the final period which hardly contributes to the actual exposure as shown by the curve h.

FIG. 6 shows a shutter time input section of the electronic flash device of the present invention. This is a system in which mechanical displacement is used as a shutter speed signal and is transmitted to the electronic flash device 2. First, the mechanism on the side of the camera body 1 will be described with reference to FIG. A cam 17 is fixed below the shutter dial 5 and rotates integrally with the dial 5. There is a concentric circle portion 17c on the cam 17, which corresponds to a shutter speed range such as 1/1000 seconds or 1/500 seconds that cannot be flashed with a focal plane shutter. The radius of the next portion 17b is sequentially changed according to the shutter speed. The portion 17b is connected by a smooth curve in this figure, but it may be stepwise. The area of the next portion 17a corresponds to the shutter speed area in which sufficient flash photography can be performed in a long time. This portion 17a may also be concentric. The direction of the lift of the cam 17 is changed by the lever 18.

The lever 18 is biased in a clockwise direction by a spring 20 around a shaft 19. Therefore, the pin 21 planted at one end of the lever 18 approaches the mounting seat 4 when the lift of the cam 17 is large, and moves away when the cam 17 is small.

A hook 22 for preventing the electronic flash device 2 from being detached is also provided so that the stroke of such a signal can be reliably transmitted.

The above is provided in the camera body 1 of the present embodiment.

An example of the electronic flash device 2 that receives a signal from the camera body 1 of this embodiment is shown in FIG.

The lever 23 of the mounting foot 3 is rotatable about an axis 24, and when the lever 23 is rotated to the left by contact between the pin 21 and the tip 23a of the lever 23 when the lever 23 is inserted into the mounting seat 4 of the camera body 1. To do. This counterclockwise rotation angle is electrically detected by a variable resistor or the like in the electronic flash device 2 as a shutter speed signal. Since this detection can be performed by a known method, it will not be described in detail. The method of comparing the light emission time and the shutter speed in the electronic flash device 2 can be performed in the same manner as in the first embodiment. In the above embodiments, a plurality of shutter speed signals are output according to the setting value of the shutter speed in the camera body 1, but the shutter speed signal is output only when the shutter speed is set at a specific X seconds. However, this system is sufficiently effective. Generally, the X-second time differs depending on the camera model, but the photographer uses the electronic flash device 2 when the X-second time is set.
This is because it is possible to perform flash photography without considering the difference in the model of the light emission time.

FIG. 8 shows a specific example of the circuit of the electronic flash device according to an embodiment of the present invention.

The power supply 30 supplies power to the entire circuit via the power switch S ₁ . The power supply voltage is boosted by the booster circuit 31 and charged in a main capacitor (not shown). When the charging voltage reaches a predetermined value, the voltage detection unit 32 generates a light emission enable signal and outputs the signal to the terminal u ₁ To the camera body 1 side via. When the X contact is turned on, a light emission start signal is transmitted to the light quantity control unit 33 via the synchronizing terminal x ₁ , and the light quantity control unit 3
3 starts the flash light emission of the flash discharge tube 34. The constant current source 35 generates constant currents I ₀ and I ₁ proportional to the absolute temperature. Resistor R _2, to R ₅ and switch S ₃ is to set the maximum emission time of the flash discharge tube, to generate a magnitude of a voltage signal that is inversely proportional to it according to the maximum emission time. The constant current source I ₂ , the diode D ₁ , the operational amplifier 36, the integrating capacitor C ₁ , the transistor Q ₂ , the operational amplifier 37, the resistor R ₆ , the zener diode D ₂ , and the comparator 38 are
The voltage signal is input to generate a light emission stop signal that defines the maximum flash light emission time. These resistors R _{2 to} R ₅ , switch S ₃ , comparator 36, diode D ₁ , constant current source I ₂ , capacitor C, transistor Q ₂ , operational amplifier 37, zener diode D ₂ , comparator 38.
Constitutes a light emission time limiting means. Comparator 39,
The capacitor C ₂ and the photodiode 40 form an automatic light control circuit. The automatic light control circuit measures the flash light emission amount and generates a light emission stop signal when it reaches a predetermined amount. The light emission stop signal of the light emission time limiting device and the automatic dimming circuit is
It is applied to the light quantity control unit 33 via the switches S ₃ and S ₆ and the OR gate G ₁ to stop the light emission. The terminal G ₁ inputs a light emission stop signal from the camera body 1 when so-called TTL light control is performed, and similarly applies the light emission stop signal to the light amount control means 33 via the switch S ₆ and the OR gate G ₁ . Switch S ₂ , resistance R
₁ , the transistor Q ₁ , the resistor R ₆ , the resistor R ₈ , and the transistors Q ₃ and Q ₄ constitute a reset circuit. The transistors Q ₁ , Q ₃ and Q ₄ are always in the ON state, and the capacitors C ₁ and C ₄ , respectively. Standby with C ₂ shorted (that is, in reset state). Only during the shooting operation (that is, when the X contact is ON), the transistors Q ₃ and Q ₄ are turned OFF,
Integration of the capacitors C ₁ and C ₂ is started, and the light emission stop signal of the comparator 38 or 39, whichever operates first, is controlled in light amount. After that, the shutter closes and X
When the contact is turned off, the transistors Q ₁ , Q ₃ , and Q ₄ are again turned on.
Is turned on and the capacitors C ₁ and C ₂ are reset and ready for the next shooting. The switch S ₂ is a switch for causing the flash device to emit light without operating the camera during the test. The terminal v ₁ for inputting a voltage according to the shutter speed from the camera side constitutes a shutter speed input means. Comparator 41, AND gate G ₂ , oscillator 4
2. The light emitting diode 43 constitutes a comparison circuit. This comparison circuit inputs a voltage corresponding to the maximum light emission time and the shutter speed from the switch S ₅ and the terminal v ₁ , respectively, and when the shutter speed is shorter, the light emitting diode 43 blinks at the frequency of the oscillator 42 to generate a warning. To do. In this case, either shorter the maximum emission time by operating the switch S ₃ interlocked with the selector 15 of the fourth illustrated, or the 6,7 by operating the setting member 5 Manually shutter speed of the illustrated camera shutter Slow down. When the shutter speed becomes longer than the maximum flash emission time, the light emitting diode 43 is turned off and the warning is released.

Here, the setting of the maximum light emission time by the light emission time limiting means will be described in detail. In the figure, the voltage generated in the resistors R ₄ and R ₅ is applied to the non-inverting input terminal of the OP amplifier 36 as a voltage corresponding to the maximum flash emission time. A constant voltage is input to the non-inverting input terminal of the OP amplifier 37, and its output terminal and inverting input terminal are connected to the emitter of the transistor Q ₂ . The diode-connected transistor D ₁ and transistor Q ₂ form a logarithmic compression-expansion circuit of current. Yotsute selected resistance value switch _{S 3,} for example, in the case of the figure the _R 4 + _{R 5} and _{R N,} also O
A resistor that generates a voltage applied to the non-inverting input terminal of the P amplifier 37, for example, R ₄ + R ₅ in the case of this figure is R _K. Therefore, the voltage of the non-inverting input terminal of the OP amplifier 36 is R _N I ₁ , and the voltage of the non-inverting input terminal of the OP amplifier 37 is
Since it can be written as R _K I ₁ , the following equation holds.

Here K: Boltzmann constant, q: electron charge T: absolute _temperature, I _S: D _1, reverse saturation current of _{Q 2 I} C: is the collector current of _{Q 2.} If I _C is calculated from this, Since I ₁ is proportional to the temperature, it can be expressed as I ₁ = AT (constant). Substituting this equation into the equation and eliminating I ₁ results in the following.

Further, by appropriately selecting the values of R _N and R _K , I _C
Can be an exponential current change with base 2.
Since the current is charged by the integrating capacitor C ₁ , the charging voltage V _C of the capacitor C ₁ is Becomes The sawtooth voltage is compared with the reference voltage generated by the Zener diode D _{2 by} the comparator 38.

If the voltage of the Zener diode D ₂ is Vref,
In the equation, t where Vref = Vc gives the maximum flash emission time.

Next, the operation will be described. First, in FIG. 8, when the switch S ₃ is operated to set the maximum light emission time, the resistance R
_The voltage generated at ₄ and R ₅ corresponds to the maximum light emission time. This voltage is applied to the inverting input terminal of the comparator 41, while the voltage signal corresponding to the shutter time is applied to the non-inverting input terminal of the comparator 41 via the terminal v ₁ . Then, when the shutter time becomes shorter than the maximum light emission time, the comparator 41 applies the H output to the AND gate G ₂ . Therefore, in this case, the output of the AND gate G ₂ becomes H and L at the frequency of the output of the oscillator 42, and the light-emitting diode 43 blinks to warn.

So, either shorter flash light emission time by operating the switch S _3, or longer Shiyatsutataimu. Then, the output of the comparator 41 becomes L, the light emitting diode 43 is turned off, and the warning is released.

Next, when the shutter is released, the front curtain fully opens the aperture and then the X-contact S ₇ is turned on, the transistors Q ₃ and Q ₄ are turned off, the capacitors C ₂ and C ₂ are integrated, and the comparators 38 and 39 are started. One of the two that operates earlier outputs a light emission stop signal to the light quantity control unit 33. After that, when the trailing curtain closed the aperture completely,
Alternatively hoisting when X- contact _{S 7} is turned OFF transistor _Q 1 _again, Q 3, _{Q 4} capacitors _C 1 and ON is, _{C 2} are in a state of being reset to prepare for the next photographing.

In any case, the light emission time is limited to be shorter than the full-open time of the aperture.

FIG. 9 is a block diagram generally showing a camera body to which the electronic flash device of the present invention can be attached. The photometric circuit 50 measures the subject brightness (B _V value) and the lens F value (A _V value). The circuit 51 generates a shutter time (T _V value).
The circuit 52 inputs the film sensitivity. Exposure calculation circuit 53
Inputs B _V value, S _V value, A _V value, T _V value, etc. and calculates the shutter time. The camera body further includes an AD conversion circuit 54, a shutter information display circuit 55, an electronic flash device interface circuit 56, and a hot shoe 57. The hot shoe 57 includes terminals u ₁₀ , v ₁₀ , w ₁₀ , z ₁₀ , y ₁₀ which are respectively terminals u ₁ , v ₁ , of the electronic flash device.
Connected to w ₁ , x ₁ and y ₁ , respectively. The photometric circuit 58 is
The switch S, which is a photometric circuit included in the camera body when the electronic flash device 2 is mounted and TTL light control is performed.
Reference numeral ₇ is an X contact. Figure 10 shows interface 5
6 shows a specific circuit example. The resistors 80 and 81, the transistor 82, the light emitting diode 83, the resistor 84, and the power supply Vcc form a ready light. A charge completion signal is applied from the voltage detection unit 32 shown in FIG. 8 to the ready light shown in FIG. 10 via terminals u ₁ , u ₁₀ and RDY, and the light emitting diode 83 lights up to indicate the completion of charging. FIG. 11 shows a specific circuit example of the shutter time display circuit 55. Resistance R ₄₀₁ ~ R
₄₁₁ and the light emitting diodes D _{401 to} D ₄₁₁ constitute a display circuit for displaying the shutter speed. AND gate GA
₄₀₁ to ₄₁₁ , GB ₄₀₁ to ₄₁₁ , OR gates G _{401 to} G ₄₁₁ inverters G ₄₁₂ , G ₄₁₃ , and switch S ₉ are provided from the A / D conversion circuit 54 and the shutter time generation circuit 51, respectively, to the auto shutter time and the manual shutter. Select and enter and display. The light emitting diodes D _{401 to} D ₄₁₁ display the shutter time of 1 second to 1/1000 second. Switch S ₉
Is a switch for selecting whether to display the automatic time or the manual time. When the switch is turned on, the A-D conversion circuit 54
The time of 1/1000 to 1 second is displayed by the output of, and when it is turned off, the shutter time by the output of the manual time circuit 51 is displayed. FIG. 12 shows a TTL using an electronic flash device.
The photometric circuit 58 for dimming is shown. This photometric circuit 58 includes OP amplifiers 90, 91, 92 and a comparator 9
3, a photodiode 94 for receiving light, a diode 95 for logarithmic compression, transistors 96, 97, 98, a Zener diode 99, and resistors 100, 101, 102. FIG. 13 shows a circuit for generating a voltage proportional to the film sensitivity. This circuit has resistors 103, 104, 105,
106, variable resistor 107 for introducing film sensitivity, OP
Amplifier 108, transistors 109 with uniform characteristics, 1
10 and the transistor 111 are included. FIG. 14 shows a shutter time generating circuit for generating a photometric circuit for measuring the subject brightness. This circuit includes OP amplifiers 112, 113 and resistors 114-124 resistors 125, 126, 127 for generating a voltage corresponding to a shutter time of 1 second to 1/1000 second.
Includes switch S ₁₀ to S ₁₁ that are used to select the time Shiyatsuta seconds switch interlocked. FIG. 16 is a block diagram of the exposure calculation circuit 53. This exposure calculation circuit 5
3 includes an arithmetic circuit 130, a second control circuit 131, and a magnet control circuit 132.

Next, the operation will be described. First, when the charging of the electronic flash device is completed, a charging completion signal is applied to the terminal RDY of FIG. ₁₀ through the terminals u _{1 to} u ₁₀ , the transistor 80 is turned on, and the LE for displaying the charging completion is arranged in the finder of the camera.
The D light emitting diode 83 lights up.

Next, the operation of FIG. 11 will be described. AND gate GA
₄₀₁ GB _{401 to} GA ₄₁₁ GB ₄₁₁ and OR gate G _{401 to} G
_{Reference numeral 411} is a gate for switching the display. That is, when the switch S ₉ is ON, AND gates GA _{401 to} G ₄₀₁
Since the output of the A ₄₁₁ becomes "L", the shutter time determined by the automatic time from the AD conversion circuit 54 (1 in the figure
(Seconds to 1/1000 second) signals are AND gates GB _{401 to} GB _411.
The output of the shutter at that time becomes “H”, and the light emitting diodes D _{401 to} D ₄₁₁ at that time are turned on. The AN Contrary to the now when switch S ₉ is namely that the camera operation when the OFF is performed at Maniyuaru
The outputs of the D gates GB _{401 to} GB ₄₁₁ are all "L", and the shutter time signals from the manual time generation circuit 51 are applied to the AND gates GA _{401 to} GA ₄₁₁ , respectively.
One of the light emitting diodes D _{401 to} D ₄₁₁ that displays the corresponding shutter time is lit. FIG. 12 shows a photometric circuit of the electronic flash device. The photocurrent of the photodiode 94 is I _L , the collector current of the transistor 96 is I _C ,
The voltage applied to the terminals SV-2 and SV-3 is V _S2 V
_S3 . If the diode 85 and the transistor 98 have the same characteristics, the following equation holds.

When I _C is calculated, The charging voltage of the integrating capacitor S ₉ is 0 when the X contact of the camera is O.
When N and the STA terminal becomes "L", the transistor 97,
When 98 is turned off, Becomes

The third term of this equation is at room temperature Therefore, (V _S3 −V _S2 ) is It shows that each time it changes, it changes 2 ^N times. The is shown that the amplitude of the photocurrent when the change of one step per 18m ^V connexion ASA sensitivity in resistor 107 can be varied correspondingly. When the charging voltage of the integrating capacitor 89 reaches the voltage of the Zener diode 99, the comparator 93
The output of the through contacts y ₁₀ ~y ₁ via the terminal STP of Figure 10 are output from "L" to "H" terminal STP Figure 8 switch S ₆ light quantity control unit 33 if in the a side
The emission of the electronic flash device can be stopped. FIG. 13 is a circuit for generating a voltage proportional to absolute temperature. Since the transistors 109 and 110 have uniform characteristics, the reverse saturation current I
_{If S} is equal and hFE is sufficiently large, the base current of the transistor 110 cannot be used even if neglected, and therefore the following equation holds.

If hFE is sufficiently large, I _E ≈I _C This current is proportional to absolute temperature.
If the value of R ₁₀₇ is properly selected, a voltage proportional to the absolute temperature will be generated at the terminals S _{V-2 and} S _V-3 . Also, G of the variable resistor R ₁₀₇
If the potential of the ND and the midpoint and _{V SV} (R _X is the resistance value between the midpoint of R ₁₀₇ and GND), and this voltage is also proportional to the absolute temperature.

FIG. 15 shows a shutter time generating circuit for generating a shutter time signal. The switching switch S ₁₀ S ₁₁ is a moving switch, and in this example, an analog voltage corresponding to 1 second to 1/1000 second is output from the switch S ₁₀ to the terminals MTV-1 and MTV-2 through the output of the OP amplifier 113. . The switch S ₁₁ outputs a digital signal corresponding to the shutter time to the terminal MTV-3. Further, the OP amplifier 112 is for inputting a voltage proportional to the absolute temperature from SV-3 in FIG. 13 and converting the voltage level to an appropriate voltage level for generating a voltage corresponding to the shutter time. Is.

FIG. 16 is a detailed block diagram of the exposure calculation circuit 53. Arithmetic circuit 130 receives the output of the photometric amplifier terminal B _V, inputs the data when Shiyatsuta seconds computed by entering the film sensitivity output terminal SV-1 seconds when the control circuit 131. The second control circuit 131 is normally the arithmetic circuit 130.
Is transmitted to the magnet control circuit 132 to control the shutter.

FIG. 17 shows a circuit of another electronic flash device. The points in FIG. 17 which are increased from those in FIG. 8 are comparators A _{1 to} A _3.
And AND gates G _{1 to} G ₃ , OR gate GD, resistance R _a
~ R _d . The interlocked switches S ₄ and S ₅ are set to the side a, and the shutter time information from the camera is input to the OP amplifier 36 to control the flash time. At this time, it is assumed that resistors are connected to the flash time selection switch S ₃ as shown in the figure and the voltage between the resistors is determined as shown in the figure. In this example, the voltages V _{1 to} V ₄ are determined according to the length of the flash duration, and when V ₁ is the minimum flash duration, V 1.
_{The case of 4} corresponds to the maximum flash time. V _a is set to a voltage slightly higher than the voltage V ₁ representing the minimum flash time. Similarly, V _b is set to be a voltage slightly smaller than V ₄ . Further, V _C is set to a voltage slightly higher than the potential of GND.

To explain the operation, the comparators A ₁ A _{2 form} a window comparator, and determine whether the input voltage at the terminal V ₁ is between the minimum and maximum flashing time of the electronic flash device. Comparator A ₃ is a switching switch S
₄ is for determining whether it is on the a ₁ side or the b ₁ side, and when S ₄ is set on the b ₁ side, A _{1 to} A ₃
Since the input of has fallen to the level of GND by the resistor Rd is inoperative warning circuit the output of the A ₃ as "L". The AND gate GC2 blinks the light emitting diode 43 provided in the speedlight to warn that the proper range has been exceeded. At this time, the output of the AND gate GC3 gives a warning through the terminal u ₁ by blinking the light emitting diode 83 in the camera shown in FIG.

The truth table is shown on the next page.

Note Shi guy coater time information from the camera, the pin MTV-2 of FIG. 16, is transmitted from the v ₁₀ terminal by turning on the switch S ₈ of Figure 11 to the electronic flash device.

In the above description, an example in which the shutter speed is manually set has been described, but instead of the voltage generated by the manual setting, the output of the arithmetic circuit 130, that is, the voltage according to the shutter speed at the time of automatic exposure shooting is output means. Terminal CP which is
-2, v of course during an automatic exposure shooting if As tell ₁₀ also possible to apply the present invention.

As described above, according to the present invention, since the shutter speed set by the camera is input and the information regarding the maximum flash emission time in the range where the exposure unevenness does not occur with respect to the shutter speed is displayed, while observing the display The maximum flash emission time can be adjusted to be shorter than the shutter time, thereby preventing camera shake and exposure unevenness and reflecting the photographer's intention in the shooting result without failing to shoot. It is possible to provide a flash device that realizes a camera system capable of performing the above.

[Brief description of drawings]

FIG. 1 is a diagram showing the entire camera body and electronic flash device, FIG. 2 is a diagram showing signal transmission terminals of the electronic flash device, FIG. 3 is a diagram showing emission characteristics of the electronic flash device, and FIG. FIG. 5 is a diagram showing an embodiment of the present invention, FIG. 5 is a diagram showing emission characteristics of the electronic flash device shown in FIG. 4, and FIGS. 6 and 7 are mechanical signal transmission mechanisms of the electronic flash device. FIG. 8 is a diagram showing a specific circuit example of an electronic flash device according to an embodiment of the present invention. FIG. 9 is a block diagram showing the entire camera mountable on the electronic flash device. Is a diagram showing an interface circuit of the camera, FIG. 11 is a diagram showing a shutter time display circuit of the camera, FIG. 12 is a diagram showing a photometry circuit of the electronic flash device, and FIG. 13 is a film sensitivity. FIG. 14 shows an input circuit, FIG. 14 shows a photometric circuit of a camera, and FIG. 15 shows a camera. FIG. 16 is a diagram showing a shutter time generation circuit of a camera, FIG. 16 is a diagram showing an exposure calculation circuit of a camera, and FIG. 17 is a diagram showing another embodiment of the electronic flash device of the present invention. [Explanation of Signs of Main Parts] Warning Means ... 42, 43 Adjusting Means ... 15, S ₃

Claims (2)

[Claims] 1. An electronic flash device mountable on a camera, comprising: a focal-plane shutter and a shutter speed signal generating means for generating a signal according to a set shutter speed, wherein the shutter speed from said shutter speed signal generating means The electronic flash device is provided with a warning means for issuing a warning when the shutter full open time according to the shutter speed signal is shorter than the maximum flash light emission time of the electronic flash device. 2. An electronic flash device according to claim 1, further comprising adjusting means capable of adjusting a maximum flash light emission time of the electronic flash device.