JPH0146857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a TTL photometry speedlight device, and more particularly to a light control warning device for a speedlight device that performs automatic light control by measuring reflected light from a film surface.

Normally, the shutter is closed when the camera is not controlling exposure, that is, when taking pictures, so that the imaging light does not reach the film surface. Conventionally, automatic light control devices that control the amount of light emitted by a speedlight device by metering the light reflected from the film surface have to check whether the correct exposure has been obtained until after the photo is actually taken. I couldn't know. That is, when the shutter release of the camera is performed and the shutter is opened, the imaging light reaches the film surface. On the other hand, the speedlight device starts emitting light from this point and automatically stops emitting light when the photometric value based on the light reflected from the film surface reaches the appropriate exposure.
After that, the shutter closes and the shooting of one frame is completed. However, if the light metering value based on the light reflected from the film surface does not reach the appropriate exposure even when the flash output of the speedlight device reaches its maximum, a message indicating that the exposure was outside the flash control range will be displayed after the shooting is completed, and the photographer will be notified. was warning.

In addition, in a single-lens reflex camera, a return mirror is used both as a light-receiving element for measuring the imaging light, that is, for normal light metering, and as a light-receiving element for measuring the reflected light from the film surface, that is, for performing film surface metering. Normal photometry is also possible with a device (for example, a part of the return mirror is made into a half mirror, another mirror is provided behind it, and the light from these mirrors is guided to a light receiving element for film surface photometry). It is normal for there to be a difference in the light intensity between the photometry and film surface photometry, and it is impossible to determine that the light emission amount of the speedlight device is outside the light control range based on the photometry value of this light receiving element during normal photometry. , it is inconvenient as it is, and some kind of countermeasure is desired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a speedlight device that performs normal photometry, that is, a test flash of a flash discharge tube before photographing, as described above, and displays whether or not the automatic light control device is capable of light control.

To achieve this objective, the present invention provides a correction means for switching the photometric sensitivity of the TTL photometry circuit in conjunction with the test light emission so that the photometry conditions in the normal photometry state are the same as those for film side photometry as described above. This device is configured to display whether or not the automatic light control device is capable of light control in accordance with the light measurement value normally measured during test light emission.

The following will be described in detail based on examples.

FIG. 1 is a block diagram showing a state in which a speedlight 9 according to the present invention is attached to a camera 1. Imaging light from the subject passes through the imaging lens 2 and is guided to the viewfinder by a quick return mirror 5. The return mirror 5 has a semi-transparent mirror in part, and has a mirror 6 behind it for guiding a part of the imaging light to the photoelectric element 7. Then, when a shutter button (not shown) is pressed and the return mirror 5 is retracted from the viewfinder optical path by a known mechanism, the shutter curtain 4 begins to open. When the shutter curtain 4 is fully opened and the film surface 3 appears, the photoelectric element 7 receives the reflected light from the film surface 3 of the imaging light. That is, the photoelectric element 7 is connected to the camera so that both normal photometry, which measures the reflected light of the imaging light by the return mirror 5 and mirror 6, and film surface photometry, which measures the reflected light of the imaging light on the film surface 3, are possible. 1 is provided.

The speedlight 9 includes an automatic light control circuit 11 including a photometry circuit 12, a control circuit 14, and a warning display circuit 16.
has. The photometry circuit 12 inputs the output signal 21 of the photoelectric element 7 and the aperture signal 22 based on the resistance value of the variable resistor 10 linked to the aperture preset ring (not shown) of the photographic lens 2, and the control circuit 14 inputs the output signal 21 of the photoelectric element 7 Synchro switch 8 immediately after 4 is fully open
A synchro signal 20 generated by closing the test switch 15 and a signal generated by closing the test switch 15 for test light emission are input. Furthermore, this control circuit 14
A start signal 23 for starting the flash discharge tube 13 to emit light is output to the automatic light control circuit 11, and a correction signal 24 for correcting the photometry sensitivity only when the test switch 15 is closed is output to the photometry circuit 12. Then, the warning display circuit 16 inputs the start signal 23 and a stop signal 25 that stops the light emission of the flash discharge tube 13 via the automatic dimming circuit 11 based on the photometric calculation result of the photometric circuit 12. Light emission is performed after the input of , and when the stop signal 25 is not input, the light emitting diode 17 is driven for a predetermined time warning after the light emission.

FIG. 2 shows connections between the drive circuit section of the discharge tube 13 of the automatic light control circuit 11 and each block in FIG. When the main switch 34 is closed, the conventional DC-DC converter 30 begins to generate a high voltage. At the output end of the DC-DC converter 30 is a main capacitor 37 that charges electric charge for discharge.
is connected. As the main capacitor 37 continues to charge and the high voltage output of the DC-DC converter 30 reaches a predetermined value, the neon tube 31 discharges and lights up, and although not shown in FIG. A ready signal 26 indicating this is transmitted to the warning display circuit 16.

When the synchro switch 8 provided on the camera 1 or the test switch 15 provided on the speedlight 9 is closed, a start signal 23 is output from the control circuit 14 for a certain period of time. The start signal 23 turns on the main thyristor 32 and starts the discharge tube 13 to emit light. At the same time, the start signal 23 is input to the warning display circuit 16, informing that the light emission has started.

Now, when the test switch 15 is closed, the control circuit 14 outputs the correction signal 24 to the photometry circuit 12. On the other hand, when the synchro switch 8 is closed, this correction signal 24 is not output. Further, the correction signal 24 includes a correction signal 24a for adding reflectance information to correct the difference in reflectance between the mirror during normal photometry by the photoelectric element 7 and the film surface during film surface photometry, and a correction signal 24a for adding reflectance information when the aperture blades are opened. It includes a correction signal 24b for adding aperture information to perform correction according to the difference in the amount of imaging light between the time and the time of aperture.

Now, when the discharge tube 13 starts emitting light and the imaging light passing through the photographing lens 2 reaches an appropriate light amount, that is, when the emitted light amount reaches the required light amount, the photometry circuit 12 outputs a stop signal 25. This stop signal 25 turns on the auxiliary thyristor 33,
The charge in the capacitor 35 reverse biases the main thyristor 32 to turn it off. Therefore, the discharge tube 13 stops emitting light. At the same time, this stop signal 25 is input to the warning display circuit 16 to inform that the light emission has been stopped. When the photographing conditions are outside the light control range of the automatic light control circuit 11, the stop signal 25 is not output.

Further, when the discharge tube 13 emits light, the high voltage output voltage of the DC-DC converter 30 decreases, so the output of the ready signal 26 is interrupted. That is, the ready signal 26 is output only when the neon tube 31 is lit.

If the stop signal 25 is not input after the start signal 23 is input, the warning display circuit 16
After the discharge tube 13 emits light, the light emitting diode 17 blinks for a certain period of time from when the ready signal 26 is input again. That is, when the light is outside the dimming range, a warning is given by blinking the light emitting diode 17.

Therefore, at the time of test emission, the warning display circuit 16
The warning display circuit 16 notifies whether automatic dimming is possible or not depending on the presence or absence of the stop signal 25, and at the time of main light emission, the warning display circuit 16 notifies whether automatic dimming is completed or failed depending on the presence or absence of the stop signal.

If you perform a test flash with the aperture blades narrowed down, the photometric circuit 1 will use the aperture information based on the resistance value of the variable resistor 10 linked to the aperture preset ring.
You don't have to put it in 2.

As described above, since the speedlight device according to the present invention newly includes the control circuit 14 in the conventionally known automatic light control circuit, the photometry sensitivity of the photometry circuit 12 is controlled by the control circuit 14 during the test flash as described above. Since the exposure can be changed according to the correction signals 24a and 24b output by the camera, it is possible to know whether or not proper exposure can be obtained without actually taking a picture.

a photometric circuit 12 operating as described above;
The specific circuit connections of the control circuit 14 and the warning display circuit 16 are shown in FIG.

In FIG. 3, the terminal +Vcc is the terminal that is supplied with power by the battery 36 in FIG. 2, and the terminals A, B, and C are the terminals A, B, and C in FIG.
Represents C.

The photometric circuit 12 is configured to cause a photocurrent proportional to the amount of light received by the photoelectric element 7 to flow through the integrating capacitor _C1 . In a constant current charging circuit using a photoelectric element 7 of an integrating capacitor C ₁ , which is configured by amplifiers A ₁ , A ₂ , A ₃ , a transistor Q ₁ and a diode, if the non-inverting input voltages of amplifiers A ₂ and A ₃ are equal, Integrating capacitor C ₁ is charged by a current equal to the photocurrent generated in photoelectric element 7 .
When this charging voltage reaches a predetermined constant voltage, an amplifier acts as a comparator.
The output of _A4 changes from the "L" level to the "H" level, and a stop signal 25 is output. The photometric sensitivity of this photometric circuit 12 is determined by the ratio of the photocurrent of the photoelectric element 7 and the charging current of the integrating capacitor _C1 .
Therefore, the greater the charging current of the integrating capacitor _C1 , the higher the photometric sensitivity. A resistor R1 and a variable resistor ₁₀ are provided to change the charging current of the integrating capacitor _C1 , and are supplied with power from constant current sources _CS1 and _CS2 . Constant current sources CS ₁ and CS ₂
It is assumed that the current values I ₁ and I ₂ have a temperature coefficient proportional to the absolute temperature. The current I ₁ flowing through the resistor R ₁ is provided so as to be bypassed by the transistor Q ₃ , and the current I ₂ flowing through the variable resistor 10 is provided so as to be bypassed by the transistor Q ₄ .
When the current I ₁ is bypassed by the transistor Q ₃ , the output voltage of the amplifier A ₁ decreases following the decrease in the output voltage of the amplifier A ₂ , and as a result, the charging current of the integrating capacitor C ₁ decreases. That is, the photometric sensitivity decreases depending on the ON state of transistor _Q3 .
The amount of reduction in photometric sensitivity caused by this resistor R ₁ is set to be equal to the difference in photometric values between normal photometry and film surface photometry when the same subject is photometered. On the other hand, when the current I ₂ flows through the variable resistor 10, the output voltage of the amplifier A ₃ increases, and as a result, the charging current of the integrating capacitor C ₁ decreases. That is, the photometric sensitivity decreases due to the OFF state of transistor _Q4 . The amount of reduction in sensitivity caused by the variable resistor 10 is set to be proportional to the amount of reduction by the aperture preset ring. That is, when the aperture preset ring is placed in the open position, the resistance value of the variable resistor 10 becomes zero. Note that in the steady state, transistors Q ₃ and Q ₆ are in the OFF state,
Transistors Q ₂ , Q ₄ , and Q ₅ are each in an ON state.

Further, the control circuit 14 is provided with a one-shot multivibrator 40 that outputs a voltage at the "H" level for a certain period of time as a start signal 23 when the synchro switch 8 or the test switch 15 is closed.

Next, the operation of displaying a warning display element to indicate whether dimming is possible or not through test light emission will be described.

When the test switch 15 is opened, the start signal 23 is output from the one-shot multivibrator 40 as described above, and the transistor
Q ₇ and Q ₈ are in the ON state, resulting in the transistor
Q ₃ becomes ON and transistor Q ₄ becomes OFF. In addition, the start signal 23 turns transistor Q ₆ on, and transistor Q ₂ turns off.
become a state. The output of this start signal 23 causes the discharge tube 13 to start emitting light. Then, the photoelectric element 7 receives the reflected light from the subject due to this light emission as imaging light via the quick return mirror 5. However, as mentioned above, the transistor
Since Q ₃ is in the ON state, the photometric sensitivity has decreased so that the photometric value is the same as the film surface photometry.
At the same time, transistor _Q4 is also in the OFF state, so
As described above, aperture information is added by the variable resistor 10, and the photometric sensitivity is further reduced by this amount.
The discharge tube 13 continues to emit light until the photometered value reaches the optimum value. When the amount of light emission reaches the optimum value, amplifier _A4 outputs a stop signal 25 to stop the discharge tube 13 from emitting light.

In the warning display circuit 16, in a steady state, the output of the amplifier _A5 , which functions as a comparator, is "L".
level. Therefore, the oscillator made up of gate elements G ₁ , G ₂ , and G ₃ , which oscillates at a period determined by capacitor C ₃ and resistor R ₃ , is not oscillating.
Further, unless the ready signal 26 is input to the gate element _G4 , the transistor _Q13 cannot be turned on and off according to the oscillation cycle, and the LED 17 does not blink.

As described above, when the start signal 23 is input, the transistor _Q11 turns on and charges the capacitor _C2 with the power supply voltage +Vcc. At this time, the output of amplifier _A5 becomes “H” level and the gate element
An oscillation signal is obtained at the output of G ₃ , but the ready signal 26 goes “L” at the same time as the start signal 23 is input.
level, so the LED 17 does not blink. When the start signal 23 is no longer input, the transistor _Q11 is turned off, and the charge in the capacitor _C2 is discharged via the resistor _R2 . moreover,
When the stop signal 25 is input, the transistor
Q ₉ , Q ₁₀ and Q ₁₂ are turned ON, and capacitor C ₂
The charge is rapidly discharged by transistor _Q12 . Therefore, after inputting the start signal 25, if the speedlight 9 is dimmable, the stop signal 2 is input.
5 is input, the output of amplifier A ₅ immediately becomes “H”
level to “L” level. Further, when the light is outside the dimming range, the stop signal 25 is not input, so the output of the amplifier _A5 is at the "H" level while the charge in the capacitor _C2 is discharged by the resistor _R2 until it reaches a constant voltage. During this "H" level period, the oscillator continues to oscillate, but after the discharge tube 13 completes light emission, the ready signal 26 becomes "H" again.
When the level is reached, this oscillation signal drives the LED 17 via the gate element G ₄ and the transistor Q ₁₃ to blink, thereby warning the photographer for a certain period of time.

Note that if the ready signal 26 is not provided from the beginning, the gate element _G4 is omitted. At this time, if the light is within the dimming range, the LED 17 lights up by the input time difference between the start signal 23 and the stop signal 25. However, since the light emitting time of a discharge tube is generally extremely short, the LED 17 only lights up momentarily.

In addition, an amplifier A ₄ outputting a stop signal 25
The divided voltage of a voltage divider circuit formed by two resistors that divides the power supply voltage Vcc input to the non-inverting input terminal of the test switch 15, that is, the reference voltage may be varied in conjunction with the closing of the test switch 15. in this case,
Leave the resistor _R1 as is and remove the variable resistor 10. And a switching means that acts in the same way as transistors Q ₃ and Q ₄ , a variable resistor 10, and a resistor R ₁
A resistor or the like corresponding to the voltage may be provided in the voltage dividing circuit.

In the description of the embodiments described so far, a control circuit is used that reduces the photometric sensitivity of the photometric circuit when the speedlight performs a test flash. This is because the photometric value obtained by normal photometry is larger than the photometric value obtained by film surface photometry. That is, this is because the reflectance of the imaging light on the film surface is small. However, the transmittance of the half mirror installed in the quick return mirror is low,
If the photometric value obtained by film surface photometry becomes larger as a result, a control circuit may be provided to turn on/off the transistor _Q3 in the photometric circuit 12, contrary to the above description.

As described above, according to the present invention, when performing a test flash using a speedlight device, the photometric output is corrected in response to the difference in aperture aperture between the open aperture state during the test flash and the aperture stop state during flash photography. At the same time, by similarly correcting the photometric output in accordance with the difference between the reflectance of the sub-mirror and the reflectance of the film surface, it is possible to know whether or not an appropriate exposure can be obtained before flash photography (before the main flash). This eliminates failures due to insufficient light intensity during flash photography, minimizes wasted film, and makes it possible to test whether the flash is within the flash control range, especially when shooting with bounce light using a speedlight device. can.

Furthermore, according to the present invention, it is possible to display both whether automatic dimming is possible/impossible during test flashing and whether automatic dimming has been completed/failure during main flashing using a single warning display means, which simplifies the circuit configuration. can.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the speedlight device according to the present invention attached to a camera, Fig. 2 is a circuit diagram showing details of the discharge tube drive circuit of the automatic light control circuit in relation to other circuits, and Fig. 3. 1 shows a circuit diagram of a photometry circuit, a control circuit, and an alarm display circuit of a speedlight device according to the present invention. Explanation of symbols of main parts, photoelectric conversion means...7,
Automatic dimming means...11, Control means...14, Means for correcting the dimming means... _R1 , _Q3 , 10, _Q4 , Warning display means...16, Means for making the amount of correction variable...
...10.

Claims (1)

[Scope of Claims] 1. A flash tube that emits flash light onto a subject; and before the quick return mirror is retracted, the light reflected from the subject that has passed through the photographing lens in an open aperture state is returned to the quick return mirror. In the first photometry state, in which light is measured by a single light receiving element at the bottom of the camera body through a sub-mirror, and when the quick return mirror is retracted, the reflected light that has passed through the photographing lens in the aperture state is transferred to the film surface. a photometry means that automatically switches to a second photometry state in which photometry is performed by the single light-receiving element via a photometer, and performs photometry calculations in both of the photometry states; a test light emitting means for operating the light metering means in the first light metering state and causing the flash tube to emit light arbitrarily in order to detect in advance whether or not the flash light is possible; synchronizing means for causing the flash tube to emit light and operating the photometry means in the second photometry state to perform the automatic light adjustment; A first correction signal for correcting the photometric output of the light-receiving element is output to the photometry means in conjunction with the aperture presetting operation in accordance with the difference in aperture aperture between the aperture aperture and the aperture aperture at the time of flash photography. correction means for outputting a second correction signal to the photometry means for correcting the photometry output of the light receiving element in accordance with the difference between the reflectance of the light receiving element and the reflectance of the film surface; activating the means, the result of which is said automatic dimming/
A speedlight device characterized by comprising the same warning display means for displaying "impossible" and for activating the photometry means by the operation of the synchronization means, and displaying the completion/failure of the automatic light adjustment based on the result thereof.