JPH0477295B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flash information output device for a camera.
Conventionally, when a subject is illuminated with flashes, the reflected light from the subject is measured through the camera lens, and the flash light emission is stopped when the measured value reaches a predetermined value. Flash photography devices are known. In this type of flash photographing device, the camera and the electronic flash device are generally detachable, so a signal for stopping flash emission is transmitted from the camera side to the electronic flash device side. Therefore, a transmission line for a flash emission stop signal is required (this is true even if the camera and electronic flash device are integrated). On the other hand, it is necessary to transmit not only a flash emission stop signal but also other flash information (for example, film sensitivity and aperture value) between the electronic flash device and the camera. However, in order to reduce the amount of effort required for mounting, to eliminate obstacles to converting the circuit into an IC (increase in the number of IC pins), and to reduce the number of connection terminals when the camera and electronic flash device are detachable, The fewer signal transmission lines the better. An object of the present invention is to solve the above problems. Hereinafter, the present invention will be explained based on examples.
In the following explanation, the exposure factor will be expressed in apex display. FIG. 1 shows a circuit on the camera side, and FIG. 2 shows a circuit diagram on the electronic flash device side. The camera side circuit and the electronic flash device side circuit are connected via connection terminals T ₁ to _{T 6} of the accessory shoe 2. If the camera and electronic flash device are detachable, they are connected via connection terminals T ₁ to _{T 6} .
If the camera and electronic flash attachment are removable,
The connection terminals T ₁ to _{T 6} are electrically connected when the electronic flash device is attached to the camera. Now, to explain the camera side circuit in Figure 1,
When the power switch SW ₁ is turned ON, the power supply E ₁ supplies power between the power supply line Vcc ₁ and GND. Switch SW ₂ is turned ON by pressing the shutter button (not shown) up to the first stroke. Capacitor C ₁ is a switch
Connected in parallel with SW ₂ . The power supply control transistor Q ₁ operates while the switch SW ₂ is ON, or from when the switch SW ₂ is turned ON and then OFF until the capacitor C ₁ is charged to a predetermined voltage via the resistors R ₀ and R ₁ . It is ON during each period. Exposure control circuit 1 introduces an exposure factor from variable resistors VR ₁ to VR ₃ and photodiode PD ₁ . variable resistance
The resistance value of VR ₁ changes depending on the open aperture value AV ₀ of the lens. The variable resistor VR ₂ is set according to the step difference AV ₀ −AV between the open aperture value and the preset aperture value, where the preset aperture value preset by the preset aperture ring (not shown) of the lens is collectively referred to as AV. The resistance value changes. The resistance value of the variable resistor VR ₃ changes depending on the film sensitivity SV. Photodiode PD ₁ is a photodetector for TTL open photometry.
Generates photometric output BV−AV ₀ . Exposure control circuit 1
is the appropriate shutter speed TV based on the above exposure factors.
Calculate = BV + SV - AV. Switch SW ₃ is turned on when the shutter button is pushed to the second stroke. The exposure control circuit 1 excites the electromagnetic release magnet Mg ₁ in response to the ON of the switch SW ₃ , and starts the mechanical sequence of the camera (stopping down the aperture, raising the mirror, releasing the shutter front curtain, etc.). Then, the above calculation result is stored in conjunction with, for example, mirror up. In addition, the exposure control circuit 1
For example, in response to turning on the switch SW ₃ , the magnet Mg ₂ is energized to prevent the shutter trailing curtain from running. Appropriate shutter time from the time the front shutter curtain runs
Magnet Mg ₂ after the time corresponding to TV has passed.
is demagnetized and the rear shutter curtain runs. switch
Transistor Q ₂ connected in parallel with SW ₂ turns on, for example, in response to switch SW ₃ turning on, and turns off in response to completion of exposure control. As a result, the transistor _Q1 is turned on during the exposure control, and the operation of the exposure control circuit 1 during this period is guaranteed. The exposure control circuit 1 applies a voltage according to the film sensitivity SV to the voltage follower (OP amplifier A ₃₂₎ .The photodiode PD ₁₀ for TTL photometry is OP
Connected between the positive and negative input terminals of amplifier _A33 . Reference power supply E ₃₁ biases the positive input terminal of OP amplifier A ₃₃ . The logarithmic compression diode _D10 forms a negative feedback loop of the OP amplifier _A33 . Logarithmic expansion transistor Q ₃₄ converts the output voltage of OP amplifier A ₃₃ into a current. The output voltage of op amp A ₃₂ biases the emitter of transistor Q ₃₄ . Integrating capacitor C ₁₀ is charged with the collector current of transistor Q ₃₄ . Comparator A ₃₁ is an integrating capacitor
When the charging voltage of C ₁₀ reaches a predetermined relationship with the reference voltage E ₃₀ , the transistor Q ₃₂ is turned on. A synchro switch SW ₃₁ having terminals a and b selects terminal a before the leading shutter curtain runs, switches to terminal b when the shutter is fully open, and selects terminal a again when the trailing shutter curtain finishes running. Transistor Q ₃₆ connected in parallel with integrating capacitor C ₁₀ is turned on when synchro switch SW ₃₁ selects terminal a, shorting the integrating capacitor C ₁₀ , and when synchro switch SW ₃₁ selects terminal b, When the current is present, it turns OFF and allows the integrating capacitor _C10 to charge. A circuit 50 surrounded by a dotted line constitutes a photometry circuit for generating a TTL light emission stop signal. The battery check circuit BC is a transistor when the voltage of the power supply _E1 is compatible with the operation of the camera side circuit.
Turn on Q ₃ , Q ₃₇ , and Q ₃₈ . These are switches
SW ₁ is also OFF when transistor Q ₁ is OFF. The transistor _Q35 is turned on in synchronization with the light emission of the electronic flash device, as will be described later. The photometry circuit 50 for generating a TTL light emission stop signal includes a transistor Q ₃₅ ,
When Q ₃₇ is ON, it receives power from power supply E ₁ and operates. Transistor Q ₃₁ is transistor Q ₃₅
Turns on when turned on. Switch SW ₅ is connected in parallel to transistor Q ₃ , and the power switch
Turns ON and OFF in the opposite phase to SW ₁ ON and OFF. For example, the switch SW ₃₀ works in conjunction with the mirror up.
It turns on and turns off when the exposure ends. The exposure control circuit 1 memorizes the proper shutter time TV when the switch SW ₃₀ is turned ON, and releases it when the switch SW 30 is turned OFF. Transistors Q ₃₀ and Q ₃₃ are of switch SW ₃₀ .
Turns ON and OFF in synchronization with ON and OFF. The exposure control circuit 1 determines the flash exposure factor AV− based on the exposure factor introduced from the variable resistors VR ₁ to VR ₃ .
Calculate SV and apply it to voltage follower (OP
Amplifier) Apply to A ₃₀ . OP amplifier A ₃₀ outputs an input voltage when one or both of transistors Q ₃₀ and Q ₃₁ are OFF, and outputs no voltage when both transistors Q ₃₀ and Q ₃₁ are ON. When both transistors Q ₃₂ and Q ₃₃ are ON, the output voltage of the OP amplifier A ₃₀ becomes the voltage of the power supply line GND (logic L). Connection terminal T ₁ is terminal b of synchro switch SW ₃₁
It is connected to the. Connection terminal T ₂ is OP amplifier A ₃₀
is connected to the output terminal of the A light emitting diode LED ₁ and a transistor Q ₃ are connected between the connection terminal T ₃ and the power supply line GND. Connection terminal T ₄
is connected to the power supply line GND. The base of the transistor Q ₃₅ is connected to the connection terminal T ₅ . The lens 60 includes an optical system 61, an aperture 62, and a variable resistor VR ₁₀ that is linked to focusing. There is an interlocking relationship between the variable resistors VR ₁ and VR ₂ and the lens 60 as described above. Electric contacts T ₁₁ and T ₁₂ between the camera and the lens and a variable resistor VR ₁₀ are interposed between the continuous terminal T ₆ and the power supply line GND. Exposure control circuit 1 is connected to light emitting diode LED ₁
When a small current or a large current (details will be explained later) flows from _T3 , the anode voltage switches to flash photography mode, and the shutter time becomes synchro time. When power switch SW ₁ is OFF and switch SW ₅ is ON, the shutter is mechanically controlled not by exposure control circuit 1 but by a governor (not shown), and when power switch SW ₁ is ON and switch SW ₅ is OFF, the shutter is mechanically controlled by a governor (not shown). Sometimes the shutter is electrically controlled by an exposure control circuit 1. Next, the electronic flash device side circuit will be explained based on FIG. Power supply _E2 supplies power between power line _Vcc2 and GND when power switch _SW6 is turned on. The booster circuit 8 boosts the voltage of the power supply E ₂ and connects it to the high voltage power supply line V _CM −
Supplied between GND. The main capacitor _C3 is charged by the output of the booster circuit 8. Flash discharge tube 5
The start and stop of light emission is controlled by a light emission control circuit 6. The activation signal generating circuit 3 (consisting of, for example, a one-shot multivibrator) is connected to an input terminal a which is connected to a terminal b of a synchro switch SW ₃₁ via a connection terminal _T1 . When the synchro switch SW ₃₁ selects the terminal b, the synchro switch SW 31 has an output terminal b which outputs H (starting output) for the maximum light emission time of the electronic flash device, for example, about 2 to 3 msec. power supply line
Mode selection switch connected between Vcc ₂ and GND
SW ₂₀ is ON when in TTL dimming mode and OFF when in full flash mode. Switch SW ₂₀ ON,
OFF output (H when ON, L when OFF) is generated on signal lines P _0-10 . Figure 1 OP amplifier
The output of A ₃₀ is connected via the connection terminal T ₂ to the connection point P _0-11 ,
It is further transmitted to the base of transistor _Q22 . Variable resistor VR ₄ is for setting the aperture value and manually sets the aperture value AV set by the preset aperture ring of the lens. The variable resistor VR ₅ is for setting the film sensitivity, and the film sensitivity SV loaded in the camera
Set manually. A constant current source I ₁ that generates a current proportional to absolute temperature supplies a constant current to a series circuit of variable resistors VR ₄ and VR ₅ . Therefore, a voltage corresponding to the flash exposure factor AV-SV is generated at the connection point P _0-12 . Transistor Q ₂₁ is mode selection switch SW ₂₀
turns on when turns on. A bias current is applied to the base of the transistor _Q21 via the connection terminal _T5 . This bias current is supplied by transistor _Q21 .
When ON, transistor Q ₃₇ (shown in the first diagram)
Occurs when turned ON. When transistor Q ₂₀ is turned on, transistor Q ₃₅ (shown in the first diagram) is also turned on. ON/OFF of transistor Q ₂₀
The output (L when ON, H when OFF) is the connection point
Occurs on P _0-13 . AND gate G ₂ is a transistor
The inputs are the ON and OFF outputs of Q ₂₂ (H when ON, L when OFF), the startup output of terminal b of the startup signal generation circuit 3, and the output of signal lines P _0-10 .
When all three inputs become H, it outputs H (first light emission stop signal). AND gate G ₃ is the signal line
The output of P _0-10 and the output of connection point P _0-13 are used as inputs. Then, when the mode selection switch SW ₂₀ is OFF (in full emission mode) and/or when the transistors Q ₂₀ and Q ₂₁ are ON (when the transistors Q ₃₇ and Q ₃₈ in Fig. 1 are ON), an L signal is output. Also, when mode selection switch SW ₂₀ is ON (in TTL dimming mode) and the transistor
When Q ₂₀ and Q ₂₁ are OFF (transistor in Figure 1)
When Q ₃₇ and Q ₃₈ are OF), outputs H. The output of AND gate _G3 is called a mode mismatch signal. Switches SW ₂₂ and SW ₂₃ are interlocked with each other and are turned on and off in the same phase. When the switch SW ₂₃ is turned on, the discharge current flowing through the discharge tube 5 and the resistor R ₁₃ is integrated by the integrating circuit 7. The integrating circuit 7 monitors the amount of light emitted from the discharge tube 5 based on the integral value, and generates a second light emission stop signal when the amount of light emitted reaches a certain value (hereinafter referred to as divided light amount). Switch SW ₂₂ ,
When SW ₂₃ is turned on, it is called split flash mode.
The light emission control circuit 6 receives the starting output, the first light emitting stop signal, and the second light emitting stop signal as input, and causes the discharge tube 5 to start emitting light in response to the starting output, and also causes the discharge tube 5 to start emitting light in response to the first or second light emitting stop signal. Stops light emission. The amount of light emitted until the light emission stops due to the first light emission stop signal provides proper exposure, but the amount of light emitted until the light emission stops due to the second light emission stop signal does not necessarily provide proper exposure (details will be described later). The dimming success/failure detection circuit 30 outputs the activation output of the activation signal generation circuit 3 and AND
When the first light emission stop signal of gate _G2 is input and the first light emission stop signal is not generated while the start output is being generated (when proper exposure cannot be obtained even if the electronic flash device emits maximum light) A signal H (non-dimming display signal) is generated for a certain period of time. OP amplifier A ₁₀ has connection points P _0-11 to the positive input terminal,
A voltage of P _0-12 is applied, and a variable resistor VR ₆ is connected between the output terminal and the negative input terminal. Negative input terminal of OP amplifier A ₁₀ and power supply line
A constant current source _I10 is connected between GND. The constant current source I ₁₀ sinks a current proportional to absolute temperature. Switch SW ₂₁ has terminal a connected to signal line P _0-10 .
and a terminal b connected to the power supply line GND. When switch SW ₂₁ selects terminal a, mode selection switch SW ₂₀ is ON (TTL
(dimming mode), OP amplifier A ₁₀ is the connection point.
The voltage of P _0-11 is input, and the switch SW ₂₀ is
If it is OFF (all light emitting mode), OP amplifier A ₁₀ receives the voltage at connection points P _0-12 as input. On the contrary, switch
When SW ₂₁ selects terminal b, OP amplifier A ₁₀ unconditionally inputs the voltage at connection points P _0-12 . The variable resistor VR ₆ is disposed in the light emission path of the discharge tube 5 and is linked to an optical system 31 (for example, a Fresnel lens) that continuously changes the irradiation range of the light emission, and changes its resistance value according to the irradiation range of the light emission. changes. The resistance value of variable resistance value VR ₆ decreases as the irradiation range is narrowed (increasing the guide number of the electronic flash device), and it also increases (decreasing the guide number)
It increases as the amount increases. The output voltage of OP amplifier A ₁₀ is connected to the voltage of connection points P _0-11 and P _0-12 by variable resistor VR _6.
This is the sum of the first correction voltage determined by . A Zener diode ZD ₁₀ and resistors R ₂₈ , R ₂₉ , and R ₃₀ are connected in series between the high-voltage power supply line V _CM and GND. The Zener voltage of the Zener diode ZD ₁₀ is set equal to the lower limit of the voltage that allows the discharge tube 5 to emit light, and is usually several tens of volts. Transistors Q ₂₃ and Q ₂₄ constitute a current mirror circuit. When the charging voltage of the main capacitor _C3 becomes higher than the Zener voltage, the current determined by the charging voltage and the resistor _R20 is transferred to the transistor.
Output to the collector of Q ₂₄ . The negative input terminal of OP amplifier A ₁₁ is connected to the collector of transistor Q ₂₄ , and a logarithmic compression diode D ₂₁ is connected between the output terminal and negative input terminal of OP amplifier A ₁₁ .
The voltage of reference voltage source E ₂₀ is applied to the positive input terminal of OP amplifier A ₁₁ . A temperature compensation diode D ₂₂ is connected between the output terminal of the OP amplifier A ₁₁ and the power supply line GND.
A constant current suction source that sinks a current proportional to the absolute temperature I ₁₁
are connected in series. At its connection point P _0-14 ,
A second correction voltage corresponding to the guide number of the electronic flash device, which depends on the charging voltage of the main capacitor _C3 , is output. The positive input terminal of the OP amplifier A ₁₂ is connected to the connection point P _0-14 , and the negative input terminal is connected to the OP amplifier through the resistor R ₂₁ .
Connected to the output terminal of A ₁₀ . Resistor R ₂₂ is OP
Forming a negative feedback loop for amplifier A ₁₂ ,
Resistor R ₂₃ and constant current sink source I ₁₂ that sinks a current proportional to absolute temperature are the output terminal of OP amplifier A ₁₂ and the power supply line.
Connected in series with GND. its connection point
A first near-limit voltage corresponding to the first near-limit of the flash photography distance determined by electrical factors is output to P _0-15 . Constant current source I ₁₃ and resistor R ₂₄ , which generate a current proportional to absolute temperature, are the above-mentioned switch.
It is connected in series between the power supply line Vcc ₂ and GND via SW ₂₂ . A third correction voltage corresponding to the divided light emission amount is output to the connection point P _0-16 . Constant current source I ₁₄ that sinks a current proportional to absolute temperature and variable resistor VR ₇
are connected in series between the power supply lines, and a second near-limit voltage is generated at the connection point P _0-17 corresponding to the second near-limit of the flash shooting distance determined by optical factors. be done. The variable resistor VR ₇ is linked to the optical system 31, and its resistance value decreases when the irradiation range is narrowed, and increases when the irradiation range is expanded. OP amplifiers A ₁₃ , A ₁₄ , diodes D ₂₃ , D ₂₄ are
The second correction voltage of the connection point P _0-14 and the third correction voltage of the connection point P _0-16
When the correction voltage is input, a minimum voltage selection circuit is configured. As a result, the lower voltage of the second and third correction voltages is input to the positive input terminal of the OP amplifier _A17 . That is, when the switches SW ₂₂ and SW ₂₃ are ON, the second or third correction voltage is
When SW ₂₂ and SW ₂₃ are OFF, the second correction voltage is
Input to OP amplifier _A17 . The first correction voltage from OP amp A ₁₀ is applied to OP amp A ₁₇ via resistor R ₂₆ .
is input to the negative input terminal of Resistor R ₂₇ is an OP amplifier
A ₁₇ negative feedback loop is formed. Therefore, OP
The amplifier A ₁₇ generates a far limit voltage corresponding to the far limit of the flash photography distance based on the first correction voltage from the OP amplifier A ₁₀ and the second or third correction voltage from the minimum voltage selection circuit. OP amp A ₁₇ , resistor
R ₂₆ and R ₂₇ constitute an inverting amplifier circuit. OP amplifiers A ₁₅ , A ₁₆ , diodes D ₂₅ , D ₂₆ are connection points
A maximum voltage selection circuit is constructed which receives as input the first limit voltage of P _0-15 and the second limit voltage of connection point P _0-17 . As a result, the higher voltage of the first and second limit voltages is input to the positive input terminal of the OP amplifier _A18 . Comparator A ₁₈ compares the far limit voltage from op amp A ₁₇ with the first or second near limit voltage from the maximum voltage selection circuit. Zener diode ZD ₁₀ , voltage dividing resistor R ₂₈ ~ R ₃₀ ,
The comparators A ₁₉ , A ₂₀ and the reference voltage source E ₂₂ constitute a charging voltage monitoring circuit for the main capacitor C ₃ . Comparator A ₁₉ outputs H when the charging voltage of main capacitor C ₃ exceeds the lower limit of the flash emission voltage. comparator
_A20 outputs H when the charging voltage exceeds a voltage that enables light emission corresponding to the maximum light emission amount of the electronic flash device (hereinafter, this is referred to as charging completion). A constant current source I ₁₆ , which generates a current proportional to the absolute temperature, is connected between the power supply line Vcc ₂ and the connection terminal T ₆ . The comparator A ₂₁ receives the voltage of the connection terminal T ₆ and the voltage of the reference voltage E ₂₁ as inputs. for example,
Constant current source I ₁₆ connects variable resistor VR ₁₀ through connection terminal T ₆
(as shown in the first diagram), a voltage corresponding to the photographing distance is generated at the terminal _T6 . However, the terminal
If nothing is connected to T ₆ (when the camera shown in the first diagram is not attached to the electronic flash device), the terminal
The voltage on T ₆ rises to the voltage on the supply line Vcc ₂ .
Therefore, if the reference voltage E ₂₁ is set to the upper limit of the voltage change due to the change in the variable resistor VR ₁₀ , the terminal T ₆
When the voltage on the power supply line _Vcc2 increases, the comparator _A21 outputs L. The output of this comparator A ₂₁ acts to prevent erroneous display. A constant current source I ₁₅ that generates a current proportional to absolute temperature,
Resistors R ₃₁ and R ₃₂ and a constant current sink source I ₁₇ that sinks a current proportional to absolute temperature are connected in series between the power supply line Vcc ₂ and GND. Comparator A ₂₂ has a comparison input selection function, the voltage at connection point P _0-18 between constant current source I ₁₅ and resistor R ₃₁ , and the voltage at connection point P _0-19 between resistor R ₃₁ and the output terminal of OP amplifier A ₁₇ . and the voltage at connection terminal T ₆ are applied. The comparator A ₂₃ has a comparison input selection function, and includes the voltage at the connection point P _0-20 between the resistor R ₃₂ and the constant current source I ₁₇ , the output voltage (first or second near-limit voltage) of the maximum voltage selection circuit, and the connection The voltage at terminal T ₆ is applied. When mode selection switch SW ₂₀ is ON, the positive input terminal of comparator A ₂₂ is the connection point.
The voltage of P _0-19 is input, and the negative input terminal of comparator A ₂₃ is input the output voltage of the maximum voltage selection circuit.
Also, when mode selection switch SW ₂₀ is OFF,
The positive input terminal of the comparator A ₂₂ receives the voltage at the connection point P _0-18 , and the negative input terminal of the comparator A ₂₃ receives the voltage at the connection point P _0-20 . The negative input terminal of comparator A ₂₂ and the positive input terminal of A ₂₃ are connected to connection terminal T ₆ . Comparators A ₂₂ and A ₂₃ are window comparators. Switch SW ₉ is turned on in balanced lighting mode. Switch connected in parallel with switch SW ₉
SW ₂₄ is used when connecting an electronic flash device and a camera via an extension cord so that the illumination position of the electronic flash device relative to the subject can be arbitrarily selected, or when multiple flashes are fired, the electronic flash device is used for slave firing. Sometimes it is turned on. The display section 40 has terminals _P1 to _P13 . Terminal _P1 is
The output terminal of the AND gate _G3 and the terminal _P2 are connected to the output terminal of the dimming success/failure detection circuit 30, and the terminal _P3 is connected to the output terminal of the OP amplifier _A17 .
The output terminal of the comparator A ₁₈ is connected to the terminal P ₄ , and the output terminal of the maximum voltage selection circuit is connected to the terminal P ₅ . Terminal P ₆ is connected to power supply line Vcc ₂ via resistors R ₅₂ and R ₅₃ . The output terminals of comparators A ₂₁ , A ₂₂ , and A ₂₃ are connected to terminals P ₇ to _{P 9} , respectively. Comparator A ₂₀ , A ₁₉
The output terminals of are connected to terminals P ₁₀ and P ₁₁ , respectively. Terminal P ₁₂ is connected to signal lines P _0-10 , and inputs the ON/OFF signal of the mode selection switch. Terminal P ₁₃ turns on switches SW ₉ and SW ₂₄ ,
Takes OFF signal as input. Connection end T ₄ is the power supply line
Connected to GND. Transistor Q ₄₀ is a resistor
It is turned on by the bias of R ₅₂ and R ₅₃ . In the series circuit of transistor Q ₄₀ and resistor R ₅₁ , resistor R ₅₀
are connected in parallel. Transistor Q ₄₀ is OFF
When , a small current is supplied to the light emitting diode LED ₁ through the resistor R ₅₀ and the connecting terminal T ₃ , and the transistor Q ₄₀ is
When ON, a lighting current for lighting the light emitting diode LED ₁ is supplied to the light emitting diode 1 via the connection terminal T ₃ via the resistors R ₅₀ and R ₅₁ . Next, the electrical characteristics when the electronic flash device is attached to a camera will be described in detail. (1) In TTL dimming mode: At this time, switches SW ₂₂ and SW ₂₃ are OFF, mode selection switch SW ₂₀ is ON, and switch SW ₂₁ selects terminal a. At this time, if the camera release button is pressed to the first stroke, the transistor
Since Q ₃₀ and Q ₃₃ are OFF, OP amplifier A ₃₀ outputs the output voltage V _A30 shown below. V _A30 = αT + (AV - SV) kT / qln2 ... (1) However, T: Absolute temperature, k: Boltzmann's constant, q: Elementary charge of electron, α: Constant, Since switch SW ₂₀ is ON, the OP amplifier _A10
inputs the voltage at the connection point P _0-11 , that is, the output voltage V _A30 of the OP amplifier A ₃₀ . Therefore, the output voltage V _A10 (first correction voltage) of the OP amplifier A ₁₀ is V _A10 = αT + γT + (AV-SV) kT/qln2 (2). However, γT is the added voltage due to I ₁₀ and VR ₆ . The voltage V _C3 of the capacitor C ₃ shall be higher than the Zener voltage V _ZD10 of the Zener diode ZD ₁₀ ,
(V _C3 −V _ZD10 )≫V _BE . However, V _BE is the emitter-base voltage of transistors Q23 _{and Q24} . Further, the reverse saturation currents of the diodes D ₁ and D ₂ are assumed to be equal, and the current of the constant current suction source I ₁₁ is assumed to be i ₁₁ .
Output voltage of connection point P _0-14 (second correction voltage), i.e.
Positive input voltage of OP amp A ₁₂ V _A12 in and OP amp
Positive input voltage of A ₁₄ V _A14 in V _A12 in=V _A14 in=εT+kT/qlnV _C3 −V _ZD10 /R ₂₀・I _S −
kT／qlnin／I _S =εT＋kT／qlnV _C3 −V _ZD10 /in・R ₂₀ …
…(3). However, εT is the voltage of the reference voltage E ₂₀ proportional to the absolute temperature T, and _IS is the equal reverse saturation current of the diodes D ₁ and D ₂ . Switch SW ₂₂
Since it is OFF, the output of OP amplifier A ₁₃ is in a sufficiently high state and diode D ₃ is reverse biased.
Therefore, the input voltage V _A14 in of the OP amplifier A ₁₄ is selected and becomes the positive input voltage V _A17 in of the OP amplifier A ₁₇ . The output voltage of OP amplifier _A17 , V _A17 out, is V _A17 out=(1+R ₂₇ /R ₂₆ )V _A17 in−R ₂₇ /R ₂₆ V _A10
= (1+R ₂₇ /R ₂₆ )V _A14 in−R ₂₇ /R ₂₆ V _A10 ……(4) From equations (2) to (4), the output voltage of OP amplifier A ₁₇ is: V _A17 out=R ₂₇ /R ₂₆ kT/qln2 {(R ₂₆ /R ₂₇ +1)(
ε−k/qlni ₁₁ R ₂₀ )−(α+γ)/k/qln2 +(R ₂₆ /R ₂₇ +1)/ln2ln(V _C3 −V _ZD10 )+(S
V−AV)}...(5). Here, if R ₂₆ = R ₂₇ , equation (5) becomes It is. This output voltage V _A17 out is as described later.
Compatible with the farthest dimmable shooting distance in TTL flash control mode. This dimmable furthest shooting distance is determined by the output voltage (first correction voltage) of OP amplifier _A10 , which has maximum light output correction information that depends on the adjustment of the flash irradiation range.
It is calculated by taking into account the output voltage (second correction voltage) of the connection point _P0-14 , which has maximum light emission correction information depending on the charge voltage of the main capacitor _C3 , so the flash irradiation range can be adjusted. and is corrected according to the charging pressure of the main capacitor. Therefore, it is possible to provide proper exposure by light adjustment (light emission amount control) for a subject that is closer than the farthest photographing distance that can be photographed. (2) Switches SW ₂₂ and SW ₂₃ are OFF, mode selection switch SW ₂₀ is OFF, and switch SW ₂₁ is OFF.
When terminal a is selected (all light emitting mode): At this time, the OP amplifier A ₁₀ inputs the output voltage V _0-12 of the connection point P _0-12 . This output voltage is controlled by a variable resistance
OP amp A ₃₀ by VR ₄ , VR ₅ and constant current source I ₁
The output voltage of V is equal to _A30 . Therefore,
Each output voltage is expressed in the same way as shown in equations (2) to (6). However, the mode selector switch SW ₂₀
is OFF, the discharge tube 5 emits full light (light emission amount control is not performed), so the output voltage V _A17 out obtained by equation (6) is the only one that can obtain proper exposure in full flash mode. It will depend on the distance. (3) Switches SW ₂₂ and SW ₂₃ are ON, mode selection switch SW ₂₀ is ON, and switch SW _{21 is} ON.
TTL dimming, split light emission mode when terminal a is selected: At this time, constant current source I ₁₃ and resistor are connected to connection points P _0-16 .
The voltage determined by R ₂₄ , that is, the input voltage V _A13 in (third correction voltage) of the OP amplifier A ₁₃ is V _A13 in=η ₁ T (7). However, η ₁ is a constant determined by the resistance R ₂₄ . On the other hand, since the input voltage V _A14 in shown in equation (3) is input to OP amplifier A ₁₄ , the input voltage
The output voltage V A17 out of the OP amplifier _{A 17} changes depending on the magnitude of V _A13 in and V _A14 in. When V _A13 in < V _A14 in; In this case, the minimum voltage selection circuit selects V _A13 in, so the output voltage V _A17 out of OP amplifier A ₁₇ is calculated from equations (2), (4), and (7). V _A17 out=kT/qln2{2η ₁ −(α−γ
)/kT/qln2+(SV-AV)}...(8). Since the input voltage V _A13 in is information on the maximum light emission amount according to the divided light emission amount, the output voltage V _A17
out represents the farthest shooting distance that is possible with TTL flash control when in TTL flash control mode and split flash mode.
Note that η ₁ is selected in accordance with the divided light emission amount. When V _A13 in > V _A14 in; in this case, the minimum voltage selection circuit selects V _A14 in, so the output voltage V _A17 out of the OP amplifier A ₁₇ is similar to equation (6). this is,
This operation is performed when the main capacitor _C3 is not charged until the charging voltage satisfies the divided light emission amount, but exceeds the lower limit of the light emission voltage. Therefore, the output voltage V _A17 out is the maximum light emission amount correction information that depends on the charging voltage of the main capacitor _C3 (added to the second correction voltage) and the maximum light emission amount correction information that depends on the adjustment of the flash irradiation range. (added to the first correction voltage), so
It supports the farthest shooting distance with TTL dimming.
Note that continuous flash photography is not possible at this time.
This is because the energy of the main capacitor is consumed by one light emission. (4) Switches SW ₂₂ and SW ₂₃ are turned on, mode selection switch SW ₂₀ is turned off, and switch SW ₂₁ is turned on.
selects terminal a (full emission, split emission mode): At this time, the OP amplifier A ₁₀ inputs the output voltage P _0-12 (=V _A30 ) of the connection point P _0-12 . Therefore, each output voltage is expressed in the same way as shown in equations (2) to (8). However, mode selection switch SW ₂₀
Since it is OFF, TTL dimming is not performed. Therefore,
When V _A13 in＜V _A14 in, the output voltage V _A17 of equation (8) is
out is the only shooting distance (appropriate shooting distance) at which a proper exposure can be obtained when the above-mentioned divided flash amount is used.
corresponds to Further, when V _A13 in>V _A14 in, the output voltage V _A17 out is determined by the charging voltage of the main capacitor and the flash irradiation range, and proper exposure can be obtained. Compatible with only one shooting distance (appropriate shooting distance). (5) When switch SW ₂₁ selects terminal b: At this time, OP amplifier A ₁₀ is unconditionally connected to the connection point.
Since the output voltage V _0-12 (=V _A30 ) of P _0-12 is input, the shooting distance information explained in (2) and (4) is obtained from the OP amplifier.
Output to A ₁₇ out. (6) The electrical characteristics (1) to (5) described above were based on the assumption that the amount of light emission could be controlled steplessly within the range from zero to the maximum amount of light emission. The minimum amount of light that can be emitted is not zero but is finite. Therefore, proper exposure may not be obtained at close range. Countermeasures against this will be described below. Now, the voltage V _R23 generated at the connection point P _0-15 is V _R23 = δT (9). However, δ is a constant determined by I ₁₁ and R ₂₃ . Therefore, the input voltage of OP amplifier _A15 V _A15 in
is, V _A15 in=(1+R ₂₂ /R ₂₁ ) V _A12 in−R _2
2 /R ₂₁ V _A10 −V _R23 ...(10). From formulas (2), (3), (9), and (10), the input voltage V _A15 in is V _A15 in=R ₂₂ /R ₂₁ kT/qln2 {(R ₂₁ /R ₂₂ +1) (
ε−k/qlni ₁₁ R ₂₀ )−(α+γ)−R ₂₁ /R ₂₂ δ/k/
qln2 + (R ₂₁ /R ₂₂ +1) / ln2ln (V _C3 −V _ZD10 ) + (SV
−AV)}...(11). Here, if we set R ₂₁ = R ₂₂ to correspond to equation (6), equation (11) becomes V _A15 in=kT/qln2{2(εk/q1ni ₁₁ R ₂₀ )−(α
+γ) −δ/k/qln2 +2/ln2ln(Vc ₃ −V _ZD10 )+(SV−AV)}……(12
) Comparing equations (6) and (12), the input voltage V _A15 in is OP
The level is shifted to a lower voltage than the output voltage V _A17 out of the amplifier _A17 by an amount determined by δ. Thereby, the input voltage V _A15 in indicates the first closest photographing distance due to electrical factors. δ in equation (12)
is the fixed minimum light amount determined by the operation delay of the light emission control circuit 6, the residual light of the discharge tube from the generation of the first and second light emission stop signals until the light emission actually stops, and the accumulated energy of the main capacitor _C3 . This is the ratio to the maximum amount of light when all the lights are emitted. Usually, the guide number GN _MIN for the minimum light amount is about 1/6 to 1/10 of the guide number GN _MAX for the maximum light amount.
And the ratio is the charging voltage of the main capacitor _C3
It is relatively constant with respect to changes in Vc ₃ , while the maximum light emission amount corresponding to the guide number GN _MAX depends on the charging voltage Vc ₃ of the main capacitor C ₃ . On the other hand, the input voltage V _A16 in of the OP amplifier A ₁₆ (unrelated to the flash exposure factor) is set by the variable resistor VR ₇ linked to the auxiliary system 31, and is determined by the optical characteristics as described above. The voltage corresponds to the closest shooting distance of 2, and is expressed as V _A16 in = θT. θ is a constant determined by the constant current source I ₁₄ and the variable change VR ₇ . The actual closest distance limit is determined by the longer closest distance of the first or second closest distance determined by electrical, photographic, or optical factors. The input voltage V _A15 in, V _A16 in is determined by the maximum voltage selection circuit using OP amplifiers A ₁₅ and _{A 16} .
The voltage corresponding to the longer closest photographing distance is selected. The above are the electrical characteristics. Next, the relationship between photographing distance and voltage will be described. The guide number GN corresponding to the amount of light emitted by the electronic flash device is GN=K・2 ^SV/2 (13). However, K is a constant determined by the charging voltage of the main capacitor, its capacity, the luminous efficiency of the discharge tube, etc. Further, the constant K is K=φ・μ・√(t) (14). Here, φ is a coefficient determined by the range of light irradiated onto the subject by the optical system 31 (light collection characteristics), μ is a conversion constant when calculating the guide number, and I(t) is the amount of irradiated light. Since I(t) is proportional to the electrical energy discharged in the discharge tube, I(t)=ν・1/2・C・(V ₁ −V ₂ ) ₂ ...(15). However, ν is the coefficient for converting the electrical energy of the flash discharge tube into light energy, C is the capacitance value of the main capacitor, V ₁ is the charging voltage of the main capacitor at the start of flash discharge, and V ₂ is the voltage at the end of flash discharge. This is the residual voltage of the main capacitor. From equations (14) and (15), K=φ・μ・√νC/2・(V ₁ −V ₂ ) =φ・ρ・(V ₁ −V ₂ ) ……(16) However, ρ=μ・Let √νC/2. On the other hand, when the guide number GN is given, the relationship between the aperture value AV to obtain proper exposure and the shooting distance D (m) is GN=2 ^AV/2・D...(17), so (13 ), from equation (16), D=K・2 ^SV-AV/2 ...(18). Substituting equation (16) for K in (18), D=φ・ρ・(V ₁ −V ₂ )・2 ^SV-AV/2 ...(19) Next, logarithmize both sides of equation (19). Converting to the formula, lnD=ln(φ・ρ)+ln(V ₁ −V ₂ )+(S
V−AV) ^ln/2 = ln2/2 {2lnφρ/ln2+2/ln2
ln (V ₁ − V ₂ ) + (SV − AV)}...(20). Now, when we compare equations (6) and (20), we find that equation (6) is
kT/qln2 is the slope term of the output voltage V _A15 out, 2(εk/qlni ₁₁ R ₂₀ )−(α+γ)/kT/qln2 is the constant term (level shift term), and 2/ln2ln(Vc ₃ − V _ZD10 ) is the first variable term, and SV−AV is the second
Similarly, ln2/2 in equation (20) is the slope term of the logarithm lnD of the shooting distance, 2lnφρ/ln2 is the constant term, and 2/ln2
ln (V ₁ -V ₂ ) is the first variable term and SV-AV is the second variable term. In other words, equation (6) and equation (20) are similar. Therefore, if the slope term, constant term, and first and second variable terms in equations (6) and (20) are made to correspond, the output voltage V _A15 out will change in proportion to the logarithm of the shooting distance. . Similarly, equations (8) and (12) below also correspond to the logarithm of distance. Also the input voltage of OP amplifier A ₁₆
V _A16 in directly corresponds to the logarithm of the second closest shooting distance. Hereinafter, the light emission and light emission stopping operations will be explained with reference to FIGS. 1 and 2. (a) Operation in TTL dimming mode: Mode selection switch SW ₂₀ is ON, switches SW ₂₂ and SW ₂₃ are
It's off. Switch SW ₅ is OFF. Now, when the release button is pushed to the first stroke, transistor _Q1 turns on. At this time, switch SW ₃₀ is OFF, so transistor Q ₃₀ ,
Since Q ₃₅ is OFF, the flash exposure factor SV-AV from the OP amplifier A ₃₀ exposure control circuit 1 is output. This flash exposure factor is transmitted to the connection point P _0-11 via the connection terminal T ₂ . transistor Q ₂₂
may not turn on depending on the flash exposure factor.
On the other hand, mode selection switch SW ₂₀ is ON, transistors Q ₃ , Q ₃₇ , and Q ₃₈ are ON (power supply E ₁
When the voltage is normal), the transistor
Q ₂₀ , Q ₂₁ , and Q ₃₅ are turned ON. Therefore, the output of AND gate _G3 becomes L, and transistor _Q31 becomes
It becomes ON. By the way, when the electronic flash device is attached to the camera and the power switches SW ₁ and SW ₆ are turned on, the light emitting diode LED ₁ is supplied with a minute current from the power source E ₂ via the resistor R ₅₀ and the connection terminal T ₃ . Therefore, the exposure control circuit 1 opens and closes the shutter at synchronized seconds. When the main capacitor _C3 is fully charged, the transistor _Q40 is turned on, and the light emitting diode _LED1 lights up. Now, when you push the receipt button to the second stroke, the camera's mechanical sequence starts and switch SW ₃₀ turns ON. Then the transistor
Since Q ₃₀ and Q ₃₃ are turned on, OP amplifier A ₃₀ stops generating the flash exposure factor. Next, when the shutter is fully opened, the synchro switch SW ₃₁ switches from terminal a to terminal b. Therefore, the starting signal generating circuit 3 to which L is applied via the connection terminal _T1 generates a starting signal at the output terminal b. The light emission control circuit 6 causes the discharge tube 5 to emit light in response to the activation signal. At the same time, the transistor _Q36 is turned off, so the integrating capacitor _C10 is charged according to the reflected light from the subject. and,
When the charging voltage of the integrating capacitor _C10 becomes lower than the voltage of the reference power source _E30 , the comparator _A31 generates an H level and turns on the transistor _Q32 . By this,
Since the base of the transistor Q ₂₂ is connected to the power supply line GND via the terminal T ₂ and the transistors Q ₃₂ and Q ₃₃ , the transistor Q ₂₂ is turned on. Therefore,
The AND gate _G2 generates H (first light emission stop signal) and applies it to the light emission control circuit 6. Therefore, the discharge tube 5 stops emitting light. When the shooting is finished, transistor _Q36 turns on and short-circuits integrating capacitor _C10 . (b) Operation in full flash mode: Mode selection switch
SW ₂₀ is OFF, switches SW ₂₂ and SW ₂₃ are OFF
are doing. Switch SW ₅ is also turned off. Now, when you press the release button to the first stroke, the transistor turns off by turning off switch SW ₂₀ .
Since Q ₂₀ and Q ₂₁ are OFF, transistor Q ₃₅ is OFF.
It is. Therefore, the flash exposure factor is transmitted from the OP amplifier A ₃₀ to the connection point P _0-11 via the connection terminal T ₂ . At this time, transistor _Q22 is OFF. Next, push the release button to the second stroke and switch SW ₃₀ will turn on, so open as above.
Amplifier A ₃₀ stops the generation of flash exposure factors.
Then, when the synchro switch SW ₃₁ selects the terminal b, the starting signal generating circuit 3 generates a starting signal, so that the discharge tube 5 starts emitting light. On the other hand, since the transistor Q ₃₅ is OFF, the TTL light emission amount detection circuit 50 does not operate, so the transistors Q ₃₂ and Q ₂₂ are not turned on, so the AND gate G ₂ is H (first light emission stop signal).
does not occur. Therefore, the discharge tube 5 emits all the light corresponding to the nominal guide number and ends the light emission. (c) Operation in TTL dimming split light emission mode: Mode selection switch SW ₂₀ , switch SW ₂₂ , SW ₂₃ is
It is ON, and switch SW ₅ is OFF.
In this mode, the first stroke of the release button, the pressing of the release button to the second stroke, the subsequent dimming operation, etc. are exactly the same as those in the TTL dimming mode, but the following operations are added.
That is, when the discharge tube 5 starts emitting light, the discharge current at that time is integrated by the integrating circuit 7, and when it is detected that light has been emitted by the divided amount of light, the second light emission stop signal is emitted. It is applied to the control circuit 6. Therefore, the light emission control circuit 6 stops the light emission of the discharge tube 5 in response to the first light emission stop signal and the second light emission stop signal, whichever occurs earlier. If light emission is stopped by the first light emission stop signal, proper exposure will be obtained, but if light emission is stopped by the second light emission stop signal, proper exposure will not necessarily be obtained (probably incorrect). This is because the second light emission stop signal is not generated based on whether or not the subject illumination is appropriate, but is generated based on the convenient light emission amount called the divided light emission amount. (d) Operation in full light emission/divided light emission mode: At this time, mode selection switch SW ₂₀ is OFF, and switches SW ₂₂ and SW ₂₃ are ON. Further, switch SW ₅ is OFF. The operation in this mode is the same as the operation in the TTL dimming/divided light emission mode described above, except that the first light emission stop signal from the AND game G ₂ is not generated because the switch SW ₂₀ is OFF. Therefore, only the divided light emission amount based on the second light emission stop signal is emitted. The above operations (3-a) and (4-a) are convenient when a motor drive device is attached to the camera and continuous flash photography is performed. In other words, if you select a subject whose shooting distance is constant (relatively close), you can obtain proper exposure even with divided light emission amounts. Meanwhile, the main capacitor C ₃ when charging is completed
For such a subject, continuous flash photography is possible because it stores enough energy to fire several times. FIG. 3 shows a first implementation circuit example of the display section 40,
Figure 4 shows its external appearance. In FIG. 3, reference voltage source E ₄₀ generates a voltage proportional to absolute temperature. Multiple voltage divider resistors R ₄₀ to _{R 45}
generates a plurality of reference voltages with equal voltage differences. First comparator group
CP _1-1 to CP _1-5 use the output voltage (the farthest shooting distance or the only shooting distance) of the OP amplifier A ₁₇ as a comparison input via the terminal P ₃ . Second comparator group
CP _2-1 to CP _2-4 use the output voltage (first or second closest photographing distance) of the maximum voltage selection circuit as a comparison input via the terminal P ₅ . mode selection switch
When SW ₂₀ is ON and terminal P ₁₂ is H (in TTL dimming mode, TTL dimming/split flash mode), the first
Since NAND gate groups G _1-1 to G _1-4 output H,
AND gate groups G _3-1 to _{G 3-4} are the logic outputs of the first comparator group and the second NAND gates, respectively.
A logic output determined by the logic outputs of gate groups G _2-1 to _{G 2-4} is generated. That is, each of the first comparator groups CP _1-1 to CP _1-5 is connected to the mode selection switch.
When SW ₂₀ is ON, if the voltage corresponding to the farthest shooting distance output from OP amplifier A ₁₇ is higher than each reference voltage, it outputs H, and the second comparator group CP _2-1 to _{CP 2 -4} outputs H if the input voltage of the terminal _P5 corresponding to the first or second closest photographing distance is higher than the respective reference voltage.
Further, the second NAND gate groups G _2-1 to _{G 2-4} respectively output H when the output of the corresponding second comparator group is L, and conversely output L when the output is H. Therefore, when switch SW ₂₀ is ON,
AND gates G _3-1 to _{G 3-4} are the distance between the farthest shooting distance and the closest shooting distance (the first and second closest shooting distances and the closest shooting distance (the first and second closest shooting distances are collectively referred to). The one corresponding to the shooting distance outputs H. Next,
When mode selection switch SW ₂₀ is OFF, the second
The NAND gate group G _2-1 to G _2-4 outputs H, and terminal P ₃ has an OP corresponding to the shooting distance in full flash mode, full flash mode, or split flash mode.
The output voltage of amplifier _A17 is input. Then, the comparator which inputs the reference voltage higher than the output voltage of OP amplifier _A17 at this time outputs L,
Conversely, if a low reference voltage is input, the comparator will go high.
Output. So, for example, a comparator
CP _1-1 and CP _1-2 output L, and the comparator
If CP _1-3 and CP _1-5 are outputting H, only NAND gate G _1-2 of the first NAND gate group outputs H, and comparator CP _1-3 outputs H. Therefore, only AND gate _G3-2 outputs H. In this way, mode selection switch SW ₂₀
When is OFF, the AND gate corresponding to the only shooting distance that provides proper exposure outputs H. Light emitting diode L ₂ ~ _{L o-1} ha corresponding AND gate H
Lights up on output. Pulse generator 70 is an OR gate
When the output of _G15 is L, it outputs H, and when it changes to H, it outputs H and L alternately. The display operation will be explained below. () In TTL light control mode or TTL light control/divided light emission mode: At this time, the camera shown in the first figure and the electronic flash device shown in the second figure are connected.
The mode selection switch SW ₂₀ is turned on and H is applied to one input terminal of the AND gate G ₃ , but the transistors Q ₃₅ , Q ₃₇ , Q ₃₈ and the transistors Q ₂₀ ,
Since Q ₂₁ is ON (when the voltage of the power supply E ₁ is sufficient), the AND gate G ₃ applies L to the terminal P ₁ of the display section. OP amplifier A ₁₀ receives the voltage at connection points P _0-11 as input. Before light emission, L is applied to the terminal _P2 from the dimming success/failure detection circuit 30. Since mode selection switch SW ₂₀ is ON, comparator A ₂₂ receives the voltage at connection point P _0-19 (output of the minimum voltage selection circuit) as input, and comparator A ₂₂ receives the output of the maximum voltage selection circuit as input. TTL
When in dimming mode, press mode selection switch SW ₂₀ .
When turned on, terminal _P12 becomes H. Furthermore, the switch
SW ₉ and SW ₂₄ are OFF and terminal P ₁₃ is L. Assuming the above, the following operations are performed depending on the conditions.・ When the farthest shooting distance > lens setting distance > latest shooting distance: First, when the charging voltage of main capacitor _C3 exceeds the lower limit value for flashing, the comparator
The output of A ₁₉ (input of terminal P ₁₁ ) changes to H, but
The output of comparator A ₂₀ (input of terminal P ₁₀ ) is L
(because main capacitor _C3 is not fully charged). Therefore, when the condition of farthest photographing distance > lens setting distance > latest photographing distance is satisfied, the output of comparator A ₁₈ (input to terminal P ₄ ) becomes L.
Also, since the mode selection switch SW ₂₀ is ON, the comparator A ₂₂ is set to the voltage at the connection point P _0-19 (first, second
The comparator A 23 inputs the voltage corresponding to the farthest photographing distance determined by the correction voltage (and the third correction voltage if necessary), and the comparator A ₂₃ inputs the output voltage of the maximum voltage selection circuit (depending on the first or second limit voltage). The voltage corresponding to the most recently determined shooting distance is input. These comparators A ₂₂ and A ₂₃ are variable resistors VR ₁₀
Since the terminal voltage of is used as a common input, both outputs of comparator A ₂₃ (input of terminal P ₉ ) become H under the above conditions. On the other hand, since the terminal voltage of variable resistor VR ₁₀ (negative input voltage of comparator A ₂₁ ) changes in a voltage range lower than reference voltage E ₂₁ ,
The output of comparator A ₂₁ (input to terminal P ₇ ) becomes H. Therefore, gates G ₁₁ , G ₁₂ , G ₁₈ output H, and gates G ₁₀ , G ₁₃ to _{G 17} output L.
By the NAND gate _G10 outputting L,
Among the light emitting diodes _L2 to Ln, the light emitting diode corresponding to the shooting distance between the farthest shooting distance and the closest shooting distance lights up to display the shooting distance at which proper exposure can be obtained by TTL light control. On the other hand, since NAND gate G ₁₂ is H, light emitting diode LED ₉ ,
LED ₁₀ does not light up. Furthermore, since the NAND gate _G18 outputs H, the transistor _Q40 is turned off. On the other hand, since a minute current is supplied to the light emitting diode LED ₁ of the camera via the terminal T ₃ by turning on the power switch SW ₆ , the shutter time of the camera is set to the synchro time. Next, when main capacitor C ₃ is fully charged, the output of comparator A ₂₀ (input of terminal P ₁₀ ) goes high.
Therefore, the outputs of the NAND gates G ₁₂ and G ₁₈ turn to H. Therefore, light emitting diode LED ₁₀ ,
The LED ₁₁ lights up to indicate that the lens setting distance set by the lens 60 satisfies the above conditions. Also, since the main capacitor _C3 has been fully charged at this time, the farthest shooting distance has increased.
Due to the action of the second correction voltage, the light emitting diode L ₂ ~
The number of lights on Ln increases accordingly. When AND gate G ₁₈ outputs L, transistor Q ₄₀ turns on.
The camera's light emitting diode LED ₁ will light up to indicate that the main capacitor C ₃ is fully charged. Note that when the lens 60 does not have the variable resistor VR ₁₀ , the connection terminal T ₆ is in an open state, so the output of the comparator A ₂₁ (input of the terminal P ₇ ) changes to L, so the NAND gate G ₁₂ and the AND gate G ₁₄ outputs L regardless of other inputs. Therefore, if the light emitting diodes LED ₁₀ and LED ₁₁ do not light up at this time, the distance of the lens may be set within the range of the photographing distance indicated by the light emitting diodes L ₂ to Ln. - When the farthest shooting distance < the closest shooting distance; In this case, either the output of comparator A ₂₂ (input to terminal P ₈ ) or the output of comparator A ₂₃ (input to terminal P ₉ ) becomes H, and the other becomes L. Become. Therefore, assuming that the main capacitor _C3 is charged only to the extent that it exceeds the lower limit of the voltage that can emit light, the NAND gate _G10 becomes L, and the NAND gate _G12
Since outputs H, only the photographing distance is displayed by the light emitting diodes _L2 to Ln at this time. Then, when the main capacitor _C3 is fully charged,
Since the output of the NAND gate _G12 changes to L, one of the light emitting diodes _LED10 and _LED11 lights up. On the other hand, since the NAND gate _G13 is outputting H, when the terminal _P10 turns to H upon completion of charging,
OR gate _G15 outputs H. This activates the pulse generator 70, so the NAND gate G ₁₈
outputs H and L alternately. Therefore, the light emitting diode LED ₁ of the camera flashes to indicate that the main capacitor C ₃ is fully charged and that the lens distance setting is inappropriate. Then, the photographer operates the focusing ring of the lens 60 so that both the light emitting diodes LED ₁₀ and LED ₁₁ light up. Then, when both the light emitting diodes LED ₁₀ and LED ₁₁ light up, the outputs of the gates G ₁₃ to _{G 15} change to L, so the light emitting diode LED ₁ of the camera lights up, indicating that flash photography is possible. - When the farthest photographing distance is less than the latest photographing distance; This is caused by an inappropriate combination of aperture value and film sensitivity, insufficient charging of the main capacitor _C3 , and poor settings of the optical system 31. Therefore, the output of comparator A ₁₈ (input to terminal P ₄ ) becomes H.
Therefore, the output of NOR gate _G11 is L, and the outputs of NAND gates _G10 , _G12 , and _G18 are H. Therefore, the light emitting diode _L1 is turned on, and the light emitting diodes _L2 to Ln, _LED10 , _LED11 , and _LED1 are turned off.
This state will continue unless all of the above causes are removed. Now, when you release the camera after setting the shooting distance according to the above display operations and removing the cause of the failure and completing preparations for flash photography, automatic light emission control using TTL metering is performed. On the other hand, when synchro contact SW ₃₁ switches to terminal b, transistor Q ₂₀
turns OFF, the output of AND gate G ₃ (terminal P ₁
input) changes to H. Then, the NOR gate _G11 outputs L and the NAND gate _G10 outputs H, so the light emitting diodes _L2 to Ln are turned off. Also,
Since the NAND gate _G18 outputs H while the output of the NOR gate _G11 is L, the light emitting diode LED ₁ of the camera is turned off during this period. Furthermore, when the charging voltage of the main capacitor decreases due to flash light emission, the terminal _P10 changes to L, so that the light emitting diodes _LED10 and _LED11 also turn off. On the other hand, the OR gate _G15 outputs H and operates the pulse generator 70, but the NAND gate
_G18 outputs H while the output of NOR gate _G11 is L. Now, when the amount of light emission reaches a predetermined value, the AND gate is activated.
The light emission of the discharge tube 5 is stopped by the first light emission stop signal _G2 . In this case, the dimming success/failure detection circuit 3
Since the output of 0 remains L, if the synchro switch SW ₃₁ is switched to terminal a after flash photography is completed, the above-mentioned display operation will be repeated. Conversely, if the amount of light emission does not reach the predetermined value, the dimming success/failure detection circuit 30 outputs H for a certain period of time, so the AND gate _G16 outputs H. Therefore, after flash photography is completed, synchro switch SW ₃₁ switches to terminal a and NOR gate G ₁₁ becomes H.
, the NAND gate _G18 alternately outputs H and L, causing the light emitting diode LED ₁ of the camera to blink. This indicates a dimming failure. If the flash exposure factor SV-AV is not transmitted to the electronic flash device for some reason when the camera shown in Figures 1 and 2 is connected to the electronic flash device, switch SW ₂₁ to terminal b. Ba,
The OP amplifier A ₁₀ inputs the flash exposure factor generated at the connection points P _0-12 . Therefore, if the aperture value and film sensitivity on the camera side are manually set using variable resistors VR ₄ and VR ₅ , the above-mentioned display operation will be performed. () When in full flash mode or full flash/split flash mode: At this time, the camera shown in the first diagram and the electronic flash device shown in the second diagram are connected, so the terminal
_P7 is H. Mode selection switch SW ₂₀
It is assumed that it is OFF and the output of AND gate _G3 (output of terminal _P1 ) is L. OP amplifier A ₁₀ is the connection point
Enter the voltage of P _0-12 . The terminal P ₂ is always supplied with L from the dimming success/failure detection circuit 30. switch
When SW ₂₀ is turned OFF, terminal P ₁₂ becomes L. Also,
Since mode selection switch SW ₂₀ is OFF, comparator A ₂₂ inputs the voltage at connection points P _0-18 , and comparator A ₂₃ inputs the voltage at connection points P _0-20 . In addition, when switches SW ₉ and SW ₂₄ are OFF, terminal P ₁₃
is L. When terminal P ₁₂ is set to L, the light emitting diodes L ₂ to Ln are set to 1 depending on the only shooting distance at which proper exposure can be obtained (hereinafter referred to as the appropriate shooting distance).
Lights up only. The voltage corresponding to this appropriate photographing distance is the input voltage of terminal _P3 , as described above. - When the appropriate photographing distance>the latest photographing distance: At this time, the output of the comparator _A18 (input to the terminal _P4 ) is L, so the NOR gate _G11 outputs H and does not light the light emitting diode _L1 . Now,
When the charging voltage of the main capacitor exceeds the lower limit of the voltage that can emit light, the output of comparator _A19 (terminal
P ₁₁ input) goes high, while comparator A ₂₀
The output (input of terminal _P10 ) remains at L. At this time, since the NAND gate _G10 outputs L, any one of the light emitting diodes _L2 to Ln lights up. Of course, the input voltage of terminal P ₃ is the first and second
Information on the correction voltage (and also the third correction voltage if necessary) is taken into consideration. However, NAND gate
Since the output of G ₁₂ is still H, the light emitting diode LED ₁₀ ,
LED ₁₁ does not light up. At this time, if necessary, flash photography may be performed by matching the appropriate photographing distance indicated by the light emitting diodes _L2 to Ln with the photographing distance set by the lens. Next, when the main capacitor is fully charged,
NAND gate _G12 outputs L. On the other hand, the comparators A ₂₂ and A ₂₃ have the terminal voltage of the variable resistor VR ₁₀ as a common input, and the voltages of the connection points P _0-18 and P _0-20 as inputs. This connection point voltage provides a predetermined dead band width between the comparators A ₂₂ and A ₂₃ centered around the voltage corresponding to the appropriate photographing distance. Therefore,
When the lens setting distance (terminal voltage of variable resistor VR ₁₀ ) is within the dead band width, comparator A ₂₂ ,
Since both the outputs of _A23 (the inputs of terminals _P8 and _P9 ) become H, the light emitting diodes _LED10 and _LED11 light up. At this time, the NAND gate _G13 outputs L, so the NAND gate _G18 outputs L, causing the light emitting diode LED ₁ of the camera to light up. For this, the lens setting distance (terminal voltage of variable resistor VR ₁₀ )
is outside the dead band width, one of the light emitting diodes LED ₁₀ and LED ₁₁ lights up depending on whether the lens setting distance is too long or too short. Then, the NAND gate G ₁₃ , AND gate G ₁₄ , and OR gate G ₁₅ output H, so the pulse generator 70 is activated. Therefore, the NAND gate _G18 alternately outputs H and L to blink the light emitting diode _LED1 of the camera. This indicates that the lens setting distance does not match the appropriate photographing distance. Note that if the lens 60 is not equipped with the variable resistor VR ₁₀ , the output of the comparator A ₂₁ (terminal
_P7 input) becomes L, so the light emitting diode
LED ₁₀ and LED ₁₁ turn off. At this time, the appropriate photographing distance displayed by the light emitting diodes _L2 to Ln is matched with the lens setting distance. The camera's light emitting diode lights up when the main capacitor is fully charged.
LED ₁ lights up.・When the appropriate shooting distance is less than the latest shooting distance; In this case, the light emitting diodes _L2 to Ln, LED ₁₀ ,
LED ₁₁ and LED ₁ are turned off, and light emitting diode L ₁ is turned on. () When in bounce lighting or multiple flash lighting mode: At this time, switch SW ₉ and SW ₂₄ are turned OFF.
When it turns ON, the NAND gates G ₁₀ and G ₁₂ output H, so the light emitting diodes L ₂ to Ln,
Display by LED ₁₀ and LED ₁₁ is not performed. However, when main capacitor C ₃ is fully charged, if farthest shooting distance < most recent shooting distance or appropriate shooting distance < most recent shooting distance, and NOR gate G ₁₁ outputs L, light emitting diode L ₁ lights up and this occurs. Display. Furthermore, if the NOR gate _G11 is H, the charging of the main capacitor is completed and the NAND gate _G18 outputs L to light up the light emitting diode LED ₁ of the camera. () When the operational relationship between the camera and the electronic flash device is inconsistent: Typically, the electronic flash device shown in the second figure is TTL.
An example of this is when the camera is attached to a camera that does not have a light control function and the mode selection switch SW ₂₀ is turned on. At this time, the output of AND gate _G3 (input to terminal _P1 ) becomes H, so NOR gate _G11 outputs L. Therefore, since the NAND gates G ₁₀ , G ₁₂ , and G ₁₈ output H, the light emitting diodes L ₂ to Ln,
LED ₁ , LED ₁₀ , and LED ₁₁ are turned off. This operation is performed when transistor Q ₁ is OFF, or when the camera shown in Figures 1 and 2 is connected to an electronic flash device, switch SW ₁ is OFF and switch SW ₅ is ON.
It also occurs when FIG. 4 shows an example of the external appearance of a display section of an electronic flash device. In Figure 4, the light emitting diode _L1 has
The light emitting diodes L 2 to Ln are marked with an NG (non-gutsud) symbol, and shooting distance scales are attached to the light emitting diodes L ₂ to Ln. The light emitting diodes LED ₁₀ and LED ₁₁ have an arrow shape, and the arrow direction of each light emitting diode corresponds to the rotation direction of the focusing ring of the lens 60. Knob 71 is for setting film sensitivity and is linked to variable resistor _VR5 , and knob 72 is for setting aperture value and is linked to variable resistor _VR4 . FIG. 5 shows another example of an implementation circuit of the display section 40.
The operations of the parts labeled with the same symbols as in FIG. 3 are the same as described above. The display differs from that shown in FIG. 3 in that the distance range is displayed directly as a numerical value using a segment display. The analog multiplexer 100 periodically selects analog input voltages at the terminals P ₃ and P ₅ by the control circuit 108 and transmits the selected analog input voltages to the A/D converter 101 . The output of the A/D converter 101 is transmitted to decoder circuits 102 and 103 which perform segment decoding for data latching and display. Decoder circuits 102 and 103 latch input data in synchronization with the operation of decoder circuit 100 by control circuit 108. That is, the decoder circuit 102 repeatedly stores and refreshes only the digitized data input on the terminal _P3 side at a predetermined period, and the decoder circuit 103 stores only the digitized data input on the terminal _P5 side at a predetermined period. data refresh,
Repeat data storage. Display drive circuit 104,1
05 drives digital displays 106 and 107 according to the decoded contents of decoder circuits 102 and 103. 106 and 107 are LED segment indicators,
Or a segment display such as LCD or EC.
In the case of displays such as LCD and EC, they are naturally illuminated by a known method to enable display confirmation in dark places. Display is performed as follows. When the terminal _P12 is at H, that is, in the TTL dimming mode, the display driving circuits 104 and 105 are controlled by the control circuit 108 so that display is performed by both the segment displays 106 and 107. As mentioned above, when the NOR gate _G11 output is under the condition of L, the segment indicators 106 and 107 indicate that
NG ₁ or an equivalent character pattern is displayed. When the NAND gate G ₁₀ output becomes H, the segment display 106 displays the farthest shooting distance or appropriate shooting distance based on the terminal P ₃ input, and the segment display 107 displays the latest shooting distance based on the terminal P ₅ input. . The other operations are the same as those in FIG. 3, and will therefore be omitted. FIG. 6 is an example of the external appearance of the display section shown in FIG. FIG. 7 shows an embodiment in which the distance display can be displayed not only on the flash device but also on the camera side, and only the part related to display control on the camera side is shown. Therefore, the flash device FL side mainly shows the parts newly added to the circuit shown in FIG. 3, and the camera CA side mainly shows the parts newly added to the circuit shown in FIG. 1. Circuit elements that operate in the same way as in FIGS. 1-3 are given the same symbols. The pulse generator 153 has a constant cycle (several 10 ms to several
outputs a pulse _t1 of approximately 100ms). When the pulse t ₁ is transmitted, the transistor Q ₅₀ turns on momentarily and discharges the capacitor C ₂₀ . Due to the periodic discharging operation of the transistor _Q50 , a sawtooth wave is generated by the constant current source _I20 proportional to the absolute temperature and the capacitor _C20 , and is transmitted to the positive input terminals of the comparators _A50 and _A51 . As mentioned above, the current of the constant current source I ₂₀ is proportional to the absolute temperature, and the voltage at the terminals P ₃ and P ₅ is proportional to the absolute temperature, so convert it into a time pulse that is independent of temperature. It is for this purpose. Differentiation and waveform shaping circuit 15
0,151 means that the output of comparators A ₅₀ and A ₅₁ is L
When it changes from to H, pulses t ₂ and t ₃ are output.
The periods of pulses t ₂ and t ₃ are equal to pulse t ₁ , but their phases are different with respect to pulse t ₁ . pulse t ₁
The time interval between pulses t 1 and t ₂ corresponds to the closest shooting distance transmitted to terminal P ₅ , and the time interval between pulses t ₁ and t ₃ corresponds to terminal P ₃
This corresponds to the farthest shooting distance or appropriate shooting distance that is transmitted to the camera. When the electronic flash device selects the full light emission mode, the terminal _P12 becomes L, so the AND gate _G30 is closed and the AND gate _G31 is opened. Therefore pulse t ₁
A pulse is output from the one-shot multivibrator 152 after a certain time delay in synchronization with
It replaces pulse t ₂ . The time interval between pulse _t1 and the 152 output pulses of the one-shot multivibrator is set shorter than the time interval between pulses _t1 and _t2 . As will be described later, when the one-shot multivibrator 152 is outputting pulses, the distance display on the near side of the camera is switched to letters or pictorial symbols such as "MANUAL", for example.
When the terminal _P4 is L, the terminal _P11 is H, and the terminal _P13 is L, the transistor _Q51 generates a pulse _t1 , via the gates _G33 and _G34 .
t ₂ , t ₃ ), and this ON−OFF
The signal is transmitted to the camera side via the connection terminal _T3 . When P ₄ H or P ₁₁ L and P ₁₃ L, gate G ₃₃ closes, gate G ₃₅ opens, and one shot multi 1
55, a pulse is generated that is delayed by a certain period of time from _t1 . At that time, t ₁ and an output pulse of 155 are outputted from gate G ₃₄ , which controls transistor Q ₅₁ and is transmitted by the camera. When P ₁₃ H, gates G ₃₃ and G ₃₅ are closed, and gate G ₃₆
One-shot multivibrator 1 when opened
54, a pulse is generated that is delayed by a certain period of time from _t1 . At this time, _t1 and the output pulse of the one-shot multi 154 are output from the gate _G34 , control the transistor _Q51 , and transmit them to the camera. The delay time of one shot multi 152, 154, 155 is t ₂
The times are shorter than the shortest time and are different from each other. The signal transmitted to the camera control circuit 1' via the resistor _R100 is to switch the camera to the flash photography mode when the current is more than a minute current due to the resistor _R50 , as described above, but the signal is transmitted to the camera control circuit 1' via the resistor R50, but the signal is transmitted to the camera control circuit 1' by the pulse of the transistor _Q51 . In order to prevent malfunction caused by turning on the capacitor,
C ₂₁ and resistor R ₁₀₀ form a low-pass filter, and there is no malfunction due to pulses at t ₁ , t ₂ , t ₃ ). When transistor Q ₄₀ is ON, transistor Q ₅₁
The pulse-like ON operation causes LED ₁ to turn off for a moment, but the pulse is so fast that it cannot be visually recognized as turning off, so no flickering occurs. Comparator A ₅₂ , reference voltage E ₁₀₀ allows transistor Q ₅₁ to
It detects only pulses caused by ON, and does not respond to the blinking operation of transistor _Q40 mentioned above. When the one shot multivibrator 156 receives the H level pulse generated in the comparator A ₅₂ , its output outputs a sustained signal at the H level for a predetermined period (τ), and a new pulse is input during the period of the sustained H level signal. Then, the H level continues for a predetermined duration starting from the new pulse.
This duration (τ) is the maximum time (ω ₁ ) from the occurrence of pulse t ₁ to the occurrence of pulse t ₃
The value added is shorter than the period of t ₁ .
Therefore, the time width of the H level of the one-shot multi 156 is ω ₁ +τ, which occurs every period of t ₁ . The one-shot multi 157 is a differential circuit that outputs only when the output of the one-shot multi 156 changes from L to H, and its output is transmitted to the set input S of the SR flip-flop 158. Therefore, at pulse _t1 , flip-flop 158 is set and its output goes high. The pulse t ₂ transmitted next to t ₁ is transmitted to the reset input R of the flip-flop 158 through the gate G ₄₀ , so that the SR flip-flop 158 is reset and its output becomes L. A delay circuit is formed by resistor _R101 and capacitor _C22 , which prevents the reset pulse from being transmitted to flip-flop 158 at _t1 . Therefore, the output of flip-flop 158 goes high during the time interval (ω ₂ ) from the occurrence of pulse t ₁ to the occurrence of pulse t ₂ . 159 is a reference pulse generation circuit for counting the output time of the one-shot multi 156 and flip-flop 158;
One shot multi 156, flip flop 1
58, the gates G ₃₈ and G ₃₉ are open and the counters 160 and 161 count the time as the number of pulses. One shot multi 156
When the output changes to L, this change generates a data latch pulse in the data latch circuits 162 and 163 after a predetermined time delay of the one-shot multi 164, and the counted values of the counters 160 and 161 are stored, and the previous stored value is is refreshed. When the one shot multi vibrator 164 generates a data latch pulse, a counter reset pulse is generated which is delayed by the one shot multi vibrator 165 for a predetermined period of time.
The count value of 0,161 is reset and a standby state is entered for the next count. 166 is a display circuit having a display input switching function. During normal shooting, display data is input to the input (AV, TV) side from 1 by the Sig-1 line signal during normal shooting, and the exposure setting value or expected exposure setting value of the AV and TV value is displayed on the displays 167 and 168, respectively. Drive and display. 1 is the latch circuit 162, 163 for display data by the Sig-1 line signal when in flash photography mode.
The display switches 167 and 168 to display the distance according to the stored values of the latch circuits 162 and 163. Display is performed as follows. When the terminals P ₄ and P ₁₃ are L and the terminals P ₁₁ and P ₁₂ are H, the pulses t ₁ , t ₂ , and t ₃ mentioned above are generated, and the pulses t 1 , t 2 , and t 3 are generated, and the pulses ω ₁ +τ,
That is, the farthest photographing distance ~ ω ₁ +τ of the latch circuit 162
When the stored value of is transmitted to the display circuit 166, the term τ is always removed. When the terminal P ₁₂ is L, that is, in the non-dimming mode, the terminals P ₄ and P ₁₃ are L, and the terminal P ₁₁ is H, the output of the one-shot multi 152 is substituted for t ₂ by the comparator A ₅₁ . At this time, the latch circuit 163 stores the predetermined time of the one-shot multi 152, and the display circuit 1
66 can be identified. Therefore, the display 167 displays the appropriate distance based on the value stored in the latch circuit 162, and the display 168 displays "M".
Or display a pictogram such as "MANUAL" that allows you to identify the non-dimming mode. When terminal P ₄ is H or P ₁₁ is L, that is, when there is no proper exposure range for flash photography, or when main capacitor C ₃ is not charged to the voltage that allows light emission, t ₁ and the output of the one-shot multi 155. There will be only pulses. It is stored in the latch circuit 163,
When the display circuit 166 identifies the condition, the display 1
The display by 67, 168 is in a disappearing state. When terminal P ₁₃ is H, t ₁ and one shot multi 15
This results in 4 output pulses. It is latch circuit 163
is memorized and identified by the display circuit 166, the display 167 disappears, and the display 168 displays the word "BOUNCE" indicating that the flash device is used for bounce shooting or that the flash device is located at a different position from the camera position using an extension cord. Indicates that the camera has been placed or that flash photography will be performed using multiple flashlights. The operation of turning on, turning off, and blinking LED ₁ is performed in the same manner as in Fig. 1. FIG. 8 shows an embodiment in which a circuit for controlling the light of the flash device alone is added to the embodiment of FIG. 2. Circuit elements that are the same as in FIG. 2 are labeled with the same signals. Switches SW ₅₀ , SW ₅₁ , and SW ₅₂ are set in conjunction with each other, and when terminal a side is set, TTL dimming,
When the terminal is on the b side, the light is dimmed independently. Reference numeral 180 is an independent dimming circuit, which controls the photometry current from the photodetector PD ₂₀ on the flash device side and the variable resistors VR ₄ and VR _5.
Based on the values of AV and _SV set to Therefore, switch SW _50-52 outputs B
When the terminal is selected, the dimming operation is performed as described above by turning on _Q22 . switch
When SW ₅₁ selects the b terminal, the output of gate G ₃ is held at L. As mentioned above, the output of the gate _G3 becomes an H output when the conditions on the camera side and the conditions on the flash device side do not match, since TTL light control will not be performed if the conditions on the camera side and the conditions on the flash device side do not match during TTL light control. However, when controlling the light independently, it is not necessary that the camera conditions match the flash device conditions as described above, so there is no need to issue a warning, so the output of gate G ₃ is set to L.
It is held in Switch SW ₅₃ displays distance using AV and SV (VR ₄ , VR ₅ ) that can be set on the flash device side even when using TTL flash control, when the AV-SV signal for distance display is not transmitted from the camera side. In order to perform this, the camera switches to the b side, but if a camera as shown in FIG. 1 is used, the a side is selected. switch
SW ₂₀ is the second switch that selects dimming or non-dimming.
Same as the figure, when switch SW ₂₀ is ON, dimming mode is selected, and switch SW ₅₀ to _{SW 52} selects dimming mode.
TTL or individual dimming mode is selected. When switch SW ₂₀ is OFF, the non-dimming mode is selected regardless of the selection mode of switches SW ₅₀ to _{SW 52} . The distance display in TTL dimming mode is the same as described above. In the individual dimming mode and the individual dimming/split emission mode, the AV set to variable resistors VR ₄ and VR ₅ ,
TTL dimming mode and TTL dimming according to SV value
The same distance display is performed in each split light emission mode. In the full light emission mode, the appropriate distance is displayed in the same way as described above. As described above, according to the present invention, the calculation means for calculating the appropriate photographing distance range of the flash device is connected to the camera side external terminal and the electronic flash device side external terminal connected to the camera side external terminal before the camera starts the exposure operation. In addition to being able to transmit exposure factor information from the side, it is also possible to output a light emission stop signal from the camera side from the start of the exposure operation to the completion of the exposure operation, making it possible to use a single terminal to send and receive multiple pieces of information. have

【table】

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a camera-side circuit diagram of an embodiment of a display device for flash photography of the present invention, FIG. 2 is a circuit diagram of an electronic flash device side of an embodiment of a display device for flash photography of the present invention, and FIG.
The figure is a circuit diagram of an embodiment of the display section of the device of the present invention.
The figures are an external view of the embodiment of the display section in FIG. 3, FIG. 5 is a circuit diagram of another embodiment of the display section of the device of the present invention, and FIG.
The figure is an external view of the embodiment of the display section in Fig. 5, Fig. 7 is a circuit diagram of the embodiment of the distance display on the camera side, and Fig. 8 is the embodiment of Fig. 2 with dimming of the flash device alone. FIG. 3 is a circuit diagram of an embodiment in which a circuit is added. Explanation of symbols of main parts, photometric device...50,
PD ₁₀ , A ₃₁ to _{A 33} , means for generating second flash information...1, output terminal...T ₂ , means for detecting...
SW ₃₀ , transmission means...Q ₃₀ ~ Q ₃₃ , A ₃₀ .

Claims (1)

[Claims] 1. A camera system comprising a camera and an electronic flash device, wherein the camera comprises (a) means for outputting an information signal related to film sensitivity and a set aperture value; (c) TTL light control means that receives reflected light from the electronic flash device via a photographic lens and outputs a stop signal when the light reaches a predetermined level;
(d) outputs the information signal to the camera side first terminal before the start of the exposure operation, and outputs the stop signal to the camera side between the start and completion of the exposure operation; (e) a second terminal on the camera side; and (f) a switching means capable of outputting an output to the first terminal on the camera side; and (f) outputting a start signal for causing the electronic flash device to start emitting flash light to the second terminal on the camera side. The electronic flash device includes (a) a single flash device-side first terminal connectable to the camera-side first terminal, and (b) a flash device connectable to the camera-side second terminal. (c) a calculation means for determining an appropriate photographing distance range in which proper exposure can be obtained during flash photography; (d) a display means; and (e) the start signal via the second terminal on the flash device side. (f) stopping means for stopping the light emitting operation of the electronic flash device; (g)
The information signal and the stop signal can be inputted through the first terminal on the flash device side, the start signal can be inputted through the second terminal on the flash device side, and the information signal and the stop signal can be inputted through the second terminal on the flash device side. transmitting means for transmitting an information signal to the calculation means and transmitting the stop signal after inputting the start signal to the stop means, the calculation means determining the appropriate photographing distance based on the information signal, The camera system is characterized in that the display means displays the appropriate photographing distance range, and the stop means stops the light emitting operation in response to the stop signal.