JPS6355053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash device that automatically sets the shutter time of a camera to a value suitable for flash photography.

Conventionally, when a charge completion signal is issued for the main capacitor for storing flash energy in a flash device, a storage circuit ( This memory circuit controls the shutter speed based on a known memory value provided in, for example, a general electric shutter circuit, and if the shutter is released before the charge completion signal is issued, the shutter speed will be adjusted according to the brightness of the subject. A method for controlling the shutter speed has already been proposed.

However, such conventional devices have the following drawbacks. In other words, as is well known, in an automatic flash device, the flash energy stored in the main capacitor is consumed in the necessary amount in order to emit the flash light necessary for flash photography, and the remaining energy is stored in the main capacitor. ing. Therefore, flash photography may be possible with this remaining flash energy. For example, if half of the stored energy in the main capacitor is consumed when illuminating a subject for the first flash photography, then the remaining half of the energy can be used to take another flash photography of the subject. This is important considering that many users are now using cameras equipped with motor drive devices. In other words, when taking flash photography with a camera equipped with a motor drive device,
If you leave the motor drive device running, the shooting will progress rapidly, so why not control the shutter speed to an appropriate value by waiting for the main capacitor charge completion signal to be generated, as in conventional devices?
It becomes difficult to capture moment-to-moment changes in the same subject using a motor drive device, and there is a great risk of camera shake in flash photography before the charge completion signal is generated.

In Fig. 1, when the power switch _S1 is turned on, the main capacitor _C1 is charged by the power supply _E1 and stores electric energy for flashlight emission, and the commutation capacitor _C2 is also connected to the resistors _R1 , R. charged via ₂ ,
Accumulates electrical energy for stopping flash emission, which will be described later.

Now, after charging of capacitors C ₁ and C ₂ is completed, when the synchro switch S ₂ linked to the release of the camera is turned on, a trigger current flows from the trigger circuit 1 to the primary winding P of the trigger coil 2. As a result, a high voltage is generated in the secondary winding S. Also, when synchro switch _S2 is turned on, trigger circuit 1
generates a trigger pulse to turn on SCR (Silicon Controlled Rectifier) _D1 . Therefore, the main capacitor C ₁ , the discharge tube FT, and the SCR D ₁ form a closed circuit, so that the discharge tube ET emits flash light by being supplied with electrical energy from the main capacitor C ₁ .

This flash light emission illuminates the subject, and a portion of it is reflected by the subject and enters the light receiving element _D2 . The integrating circuit 3 temporally integrates the output of the light receiving element _D2 , and when this becomes a predetermined value, generates a trigger pulse to turn on the SCR _D3 . Therefore, SCR R ₃ is turned on, and commutating capacitor C ₂ is connected between the anode and cathode of SCR D ₁ , which is in the on state.
As a result, SCR D ₁ becomes reverse biased and turns 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.

In FIG. 2, the camera CM and flash device FL are detachable. First, the configuration of the flash device FL will be described. The positive terminal of the power supply E ₁ is the power switch S ₁ ,
It is connected to the terminal T ₁ via the resistor R ₁₀ , and its negative electrode is connected to the common terminal T ₂ . Block 5 receives power from power source _E1 when power switch _S1 is turned on. Block 5 includes circuits other than the power source E ₁ , power switch S ₁ and synchro switch S ₂ of the flash device shown in FIG. This block 5 is connected to terminal _T3 . This serves to connect synchro switch _S2 and block 5 since synchro switch _S2 is located on the camera side.

Next, we will discuss the structure of the camera commercial. This camera-side circuit uses the so-called TTL direct metering method, which measures the subject light reflected by the shutter curtain and/or film surface after the camera's shutter release and automatically controls the exposure time. Contains shutter time control circuit.

On the camera side, there are terminals T ₁ , T ₂ , T ₃ on the flash device side.
Terminals T ₄ , T ₅ , and T ₆ are provided, respectively connected to the terminals T 4 , T 5 , and T 6 . Terminal T ₄ is the base of the transistor Q _1-1 , terminal T ₅ is the negative pole of the power supply E ₂ and the transistor
The emitter of Q _1-1 is connected to the terminal T 6, and the terminal T ₆ is connected to the synchro switch S ₂ . transistor
The collector of Q _1-1 is connected to the positive pole of the power supply E ₂ through a resistor R ₂₀ . Therefore, after the flash device FL is attached to the camera CM and the terminals T _{1 to 3} and T _{4 to 6} are connected, if the power switch S ₁ is turned off, the transistor Q _1-1 is turned off. Also, when the power switch S ₁ is turned on, the base of the transistor Q _1-1 is connected to the positive terminal of the power supply E ₁ via the resistor R ₁₀ , so that it is turned on. This transistor Q _1-1
Turning on or off switches the camera operation to automatic exposure control operation or flash photography operation.

Trigger switch _S4 is turned off in conjunction with the release operation, and turned on when shutter charging 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 C ₃ via a transistor Q ₂ .
Resistor R ₂₁ connects capacitor C ₃ through transistor Q ₃
forms a series circuit with The connection point between the capacitor _C3 , the photoconductive element 10, and the resistor _R21 is connected to one input terminal (-) of the comparator _A1-1 .

A variable resistor _R22 generates a first voltage corresponding to information such as film sensitivity and aperture value. This first voltage is applied to the other input terminal (+) of the comparator A _1-1 via a field effect transistor (hereinafter referred to as FET) Q ₄ . At the connection point of resistors R _{23 and 24} , there is a second constant value to obtain the shutter speed for flash photography.
voltage is generated. This second voltage is applied to FET Q ₅
is also applied to the other input terminal (+) of the comparator A _1-1 via . The output of the comparator _A1-1 controls the magnet Mg for locking the shutter rear curtain. Transistor Q ₆ is turned on by transistors Q _1-1 ,
OFF is controlled, and the relationship is in antiphase with each other.

After attaching the flash device to the camera, first turn off the power switch _S1 when taking a photo using automatic exposure control. This turns transistor Q _1-1 off and, as a result, transistor Q ₆ turns on. When transistor Q ₆ is turned on, transistor Q ₃ and FET Q ₅ are turned off. On the other hand, since transistor Q _1-1 is off,
Transistor Q ₂ turns on and FET Q ₄ turns on. Therefore, the input terminal (+) of comparator A _1-1
Only the first voltage is applied to. On the other hand, before the release operation, trigger switch _S4 is on, so the voltage at the input terminal (-) of comparator _A1-1 is equal to power supply _E2.
A positive voltage of is applied, so that comparator A _1-1 is
Outputs a low level signal. Therefore, the magnet Mg is energized and remains in a state in which the rear curtain of the shutter is locked.

Now, when a release operation is performed, the trigger switch _S4 is turned off at the same time as the front shutter curtain starts running, so the capacitor _C3 and the photoelectric conversion element 10 form an integrating circuit. Further, the resistance value of the photoelectric conversion element 10 changes as it receives subject light reflected from the front curtain of the shutter and/or the surface of the film being exposed. Therefore, the charging time constant of capacitor _C3 corresponds to the brightness of the subject. Now, when capacitor C ₃ starts charging,
An integrated voltage that gradually decreases from the positive voltage of the power source E ₂ is applied to the input terminal (-) of the comparator A _1-1 .
And both input terminals (+), (-) of comparator A _1-1
When the voltages become equal, this comparator generates a high level signal to demagnetize the magnet Mg.
As a result, the rear shutter curtain is unlocked and the vehicle starts running. In this way, the automatic control of shutter speed using TTL direct photometry is completed. In addition,
At this time, synchro switch _S2 is turned on, but since power switch _S1 is turned off, block 5 does not operate. Therefore, no flash light is emitted.

Next, to take flash photography, turn on the power switch _S1 of the flash device FL. This turns on transistor Q _1-1 . Transistors Q ₂ , Q ₆
and FET Q ₄ are respectively turned off by turning on transistor Q _1-1 . When transistor Q ₆ is turned off, FET Q ₅ and transistor Q ₃ are each turned on. Therefore, when the trigger switch _S4 is turned off, the integrated voltage of the integrating circuit composed of the capacitor _C3 and the resistor _R21 is applied to one input terminal (-) of the comparator _A1-1 , and the other A constant voltage determined by resistors R ₂₃ and R ₂₄ is applied to the input terminal (+) of. In other words, the time from when the trigger switch _S4 is turned off until the magnet Mg is demagnetized, that is, the shutter time, is controlled to be constant regardless of the brightness of the subject, film sensitivity, or aperture value.
The shutter speed controlled to a constant value is a value that the flash device can tune to, for example, 1/60 sec.

It goes without saying that 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 therefrom reaches a predetermined value, the flash light emission is stopped.

Although the flash device described above generates a signal to set the flash synchronization time, it does not generate a signal to indicate the completion of charging.

Therefore, an object of the present invention is to supply a signal for setting the flash synchronization time and a signal for indicating charging completion through the same terminal that electrically connects the camera and the flash device, and to charge the flash device. To provide a flash device capable of supplying a signal that can clearly distinguish when charging is incomplete and when charging is completed.

In FIG. 3, the camera includes a circuit that measures the subject light that passes through the photographic lens and is reflected by the mirror toward the pentagonal prism, and controls the shutter speed in accordance with the output.

When power switch _S1 is turned on, the main capacitor included in block 5 starts charging. The neon tube _L1 is off until the main capacitor is fully charged, and then turns on. Therefore, before the charging of the main capacitor is completed, transistor Q ₁₀ is turned off and transistor Q ₁₁ is turned on. As a result, the voltage between terminals T ₁ and T ₂ is clamped by diode D ₁₁ and transistor Q ₁₁ . The light emitting diode D ₁₂ connected between the terminals T ₄ and T ₅ is therefore unable to emit light.

On the other hand, even if the transistor _Q11 is turned on by turning on the power switch _S1 , the transistors _Q1-2 are turned on, so the transistor _Q12 and the FET _Q13 are turned off. FET by turning off transistor _Q12
Q ₁₄ turns on. As a result, the current of constant current source I ₁ is connected to the input terminal (+) of comparator A _2-1 as a diode.
A voltage generated by flowing into D ₁₃ , ie, a constant voltage proportional to the logarithm of the current of the constant current source, is applied. This voltage is useful for controlling the shutter speed to a value suitable for flash photography. Since the trigger switch _S4 is turned on before the release operation, the positive voltage of the power supply _E2 is applied to the input terminal (-) of the comparator _A2-1 . Therefore, magnet
Mg is in an excited state and locks the rear shutter curtain.

Now, the main capacitor has finished charging and the neon tube
When L ₁ lights up, transistor Q ₁₀ turns on and transistor Q ₁₁ turns off, so light emitting diode D ₁₂
lights up to indicate completion of charging of the main capacitor, for example in the viewfinder on the camera side. At this time, transistor Q _1-2 remains on.

When a release operation is performed after the completion of charging is displayed, the leading shutter curtain starts running, the trigger switch _S4 is turned off, and the capacitor _C5 starts charging via the diode _D14 . The charging voltage of this capacitor _C5 appears as a voltage proportional to the logarithm of the charging time, and is applied to the input terminal (-) of the comparator _A2-1 . The comparator _A2-1 demagnetizes the magnet Mg and starts running the shutter trailing curtain when the voltages at both input terminals (+) and (-) reach a predetermined relationship. It goes without saying that the synchro switch _S2 is turned on while the leading and trailing shutter curtains are running, and flash light emission and dimming are performed. As described above, flash photography is performed at a shutter speed suitable for flash photography, for example, 1/60 sec.

Then, when the power switch S ₁ is turned off, the transistors Q _1-2 are turned off and the light emitting diode
_D12 is turned off regardless of whether the neon tube _L1 is lit or not. When transistor Q _1-2 is turned off, transistor Q ₁₂ and FET Q ₁₃ are turned on. Turning on transistor _Q12 turns off FET _Q14 .
Therefore, the shutter time is determined by the memory capacitor Cm.
is controlled to a value corresponding to the charging voltage. As is conventionally known, the charging voltage of this memory capacitor Cm is generated by a voltage proportional to the logarithm of the photocurrent generated by the diode _D15 and output by the photovoltaic element _D16 that receives the subject light, and a resistor _R30 . , film sensitivity, aperture value, and other information. Memory switch Sm is turned off in conjunction with the release operation, and the memory capacitor
This is to store the charging voltage of Cm during exposure control. When the power switch _S1 is turned off, the shutter speed is automatically controlled in accordance with the brightness of the subject.

In Figure 3, the light emitting diode D ₁₂ lights up only when the power switch S ₁ is on and the main capacitor is fully charged, and when the power switch S ₁ is off, even though the main capacitor is fully charged. It never lights up. Therefore light emitting diode D ₁₂
When lit, it indicates that the main capacitor has been charged and the power switch _S1 is turned on, that is, the shutter time is set to a value suitable for flash photography.
Also, by turning off the light, it is displayed that the shutter speed is controlled according to exposure information such as the brightness of the subject, film sensitivity, and aperture value.

In FIG. 4, an indication that the power switch _S1 is on and an indication that charging of the main capacitor is completed are performed separately.

Light-emitting diode D ₂₀ connected between terminals T ₄ and T ₅
and D ₂₁ have different lighting voltages. For example, a GaA _3P light emitting diode can be used as a light emitting diode D ₂₀ .
If we use a GaP light emitting diode as D ₂₁ ,
The lighting voltage of D ₂₀ will be lower than the lighting voltage of D ₂₁ .
Now, when power switch _S1 is turned on, transistor _Q1-1 , which has the same effect as transistor _Q1-1 , is turned on and charging of the main capacitor is started. When this charging is not completed, the neon tube _L1 does not light up, so the transistor _Q20 is turned off and the transistor _Q21 is turned on. here the diode
Suppose that the forward voltage drop of _D22-24 is smaller than the lighting voltage of light-emitting diode _D21 . Therefore, the light emitting diode _D20 lights up and the power switch _S1 is turned on, that is, the transistors _Q1-3 are turned on, indicating that the shutter time has been set to a value suitable for flash photography.

Next, when the main capacitor is fully charged, the neon tube _L1 lights up, so the transistor _Q20 is turned on and the transistor _Q21 is turned off. Therefore, the light emitting diodes D ₂₀ and D ₂₁ are released from the voltage clamp by the diode D _{22 24} and the transistor Q ₂₁ ,
Each lights up. In this state, the power switch is turned on and charging completion is displayed. Also at this time, transistors Q _1-3 are on.

The block 7 is a shutter time control circuit as shown in FIGS.

FIG. 5 shows an embodiment of the invention. In this embodiment, one light emitting diode indicates whether the power switch _S1 is turned on or when charging is completed. The transistor Q ₃₀ turns on when the main capacitor is fully charged and the neon tube L ₁ lights up, and turns off when the neon tube L ₁ goes out. When the transistor Q ₃₀ is turned off, the gate circuit G ₁ opens its gate and applies the pulse generated by the pulse generator OSC to the transistor Q ₃₁ . Diode D ₃₀ and transistor Q ₃₁ are connected between terminals T ₁ and T ₂ to control the voltage therebetween. A light emitting diode _D32 is connected between terminals _T4 and _T5 .

Now, when power switch _S1 is on and charging is not completed, transistor _Q30 is off, so
The gate of the gate circuit G ₁ is opened, and as a result the transistor Q ₃₁ is periodically turned on and off by the pulses of the pulse generator OSC. Therefore, the light emitting diode D ₃₂ repeatedly turns on and off periodically,
Displays power switch S ₁ on. At this time, transistors Q _1-4 remain on.

Next, when charging is completed, transistor Q ₃₀ is turned on, so the gate of gate circuit G ₁ is closed.
Therefore, transistor Q ₃₁ is turned off and light emitting diode D ₃₂ remains lit, indicating that charging is complete. If the power switch _S1 is turned off from this state, the light emitting diode _D32 will turn off regardless of whether charging is completed or not.

According to the present invention described above, when the charging of the flash device is not completed, the signal generation circuit outputs the first electric signal for setting the flash synchronization time and the completion of charging on the camera side. Since the second electrical signal for display (higher level than the first electrical signal) is alternately supplied to the camera side via a single terminal,
In addition to setting the flash synchronization time, if charging is not completed, the charging completion display on the camera side will blink, and then, when the flash device is fully charged, a second electrical signal will be continuously supplied to the camera side, so the camera will The charging completion indicator on the side lights up. Therefore, in the present invention, the display form clearly changes between when the flash device is not fully charged and when it is fully charged, so that the photographer can easily recognize the situation. In addition, since the signal for setting the flash synchronization time and the signal for indicating charging completion can be supplied using a single terminal between the camera and the flash device, the number of connection terminals can be reduced. can.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a flash device used in the present invention. 2 to 4 are circuit diagrams showing the idea underlying the present invention. FIG. 5 is a circuit diagram showing an embodiment of the present invention. [Explanation of symbols of main parts], Connection terminal...T ₁ ,
_T2 , signal generation circuit... _Q10 , _Q11 , _D11 , oscillation circuit...OSC, _G1 .

Claims (1)

[Claims] 1. Second time setting means for setting the shutter time to the flash synchronization time by receiving an electrical signal of a first level or higher, and receiving an electrical signal of a second level higher than the first level. an automatic flash device that is detachable from a camera and is equipped with a charging completion display means for displaying charging completion, wherein charging of the flash device is not completed when a power switch of the flash device is turned on; If so, the first electric signal at the first level and the second electric signal at the second level are alternately generated, and when charging of the flash device is completed while the power switch is turned on, a signal generation circuit that continuously generates the second electric signal; and a unit that supplies the first and second electric signals from the signal generation circuit to the second time setting means and the charging completion display means of the camera. An automatic light adjustment flash device for a camera, characterized in that it is equipped with a connection terminal.