JPS645686B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photometric device for flash photography, and particularly to a photometric device that takes into account the lighting contrast between standing light and flash light.

Prior Art Previously, in Japanese Patent Application Laid-Open No. 10569/1983, the applicant proposed a photometer for flash photography that also takes into account ambient light, and calculated the lighting contrast between ambient light and flash light measured by this device. made it possible to do so.

Purpose of the Invention In addition, in the present invention, the lighting contrast can be set, and the amount of flash light emission (hereinafter referred to as
Although the amount of received flash light obtained by photometry or calculation is sometimes referred to as the amount of flash light emission, it essentially represents the amount of contribution to photography due to the light emission of the flash light emitting device. ) and the amount of flash light obtained by photometry. In other words, it is possible to know how much it is necessary to change the amount of light emitted by the flash device used in order to take a picture with the lighting contrast desired by the photographer. Therefore, for example, when using a flash device with a variable amount of light emission, it is possible to prevent excess energy loss by emitting light with the minimum amount of light at the time of photometry.

Incidentally, the lighting contrast is the ratio between the amount of constant light and the amount of flash light, or the difference in apex value.

Structure of the Invention For this reason, the present invention provides a light emission amount photometer that measures the light emission of a flash device emitted in advance and outputs an electric signal corresponding to the amount of contribution of the flash light to photography, and a light emission amount metering means that measures the light emission of a flash device emitted in advance and outputs an electric signal corresponding to the amount of contribution of the flash light to photography, and A constant light metering means for outputting an electrical signal corresponding to the amount of light received by the element, an exposure value output means for outputting a signal corresponding to the exposure time, and a ratio between the amount of contribution of the steady light to the amount of contribution to the photographing of flash light and the amount of contribution to the photographing of flash light. lighting contrast output means for outputting a signal corresponding to a set lighting contrast defined as; a signal corresponding to the lighting contrast; an output signal of the ambient light metering means; and a signal corresponding to the exposure time. a first calculation means for calculating a signal corresponding to the amount of contribution of flash light to photography necessary to obtain the lighting contrast; an output signal of the light emission amount photometry means and a signal obtained by the first calculation means; This invention proposes a new photometric device for flash photography, which is characterized by comprising a second calculation means for calculating the difference in the apex system.

Further, as another aspect of the present invention, there is provided a light emission amount metering means for metering the light emitted by a flash device emitted in advance and outputting an electric signal corresponding to the amount of contribution of the flash to photography, and a signal corresponding to the aperture value and Exposure value output means that outputs a signal corresponding to film sensitivity; and lighting that outputs a signal corresponding to a set lighting contrast defined as the ratio of the amount of contribution of steady light to the amount of contribution to photography and the amount of contribution of flash light to photography.・Contrast output means;
Flash light necessary to obtain the above-mentioned lighting contrast to achieve proper exposure based on the signal corresponding to the above-mentioned lighting contrast, the signal corresponding to the aperture value output from the exposure value output means, and the signal corresponding to the film sensitivity. a first calculation means for calculating a signal corresponding to the amount of contribution to photography; and a second calculation means for calculating the difference in the apex system between the output signal of the light emission amount photometry means and the signal obtained by the first calculation means. The present invention proposes a new photometric device for flash photography, which is characterized by comprising a calculation means.

Embodiments Hereinafter, embodiments of the present invention shown in the drawings will be described in detail.

FIG. 1 is a circuit diagram showing an embodiment of a photometric device according to the present invention, and in the figure, electrical signal lines with diagonal lines indicate multi-bit digital signals. In FIG. 1, the photometry circuit includes a light receiving element PD, a logarithmic compression diode _D1 , and an operational amplifier _OA1 , and outputs a potential obtained by logarithmically compressing the intensity of light incident on the light receiving element PD. Resistor R ₁ and capacitor C ₁ are low-pass filters that smooth the output of the photometric circuit. Transistor BT ₁ is a transistor for logarithmic expansion, transistor BT ₂ is a transistor for current mirror, or the circuit composed of diodes D ₂ , D ₃ and capacitor C ₂ logarithmically compresses the integral value of the current flowing into this circuit. Voltage capacitor C ₂
This is a logarithmic compression integrator circuit with outputs at both ends.
FT ₁ , FT ₂ , FT ₃ , FT ₄ are switch FETs, 1
is an A-D converter, _S1 is a switch for starting photometry, and switch _S2 linked to this is a flash device (not shown).
This is the switch that starts the light emission.

2 is a timing control circuit, the specific circuit of which is shown in FIG. 2, and its time chart shown in FIG. L ₁ and L ₂ are latch circuits, 4 is an exposure time setting device, 5 is a lighting/contrast setting device, 6 is a film sensitivity setting device, and 3 is an arithmetic circuit. 7 is arithmetic circuit 3
8 is a display device for displaying the difference between the amount of light emitted from the flash device and the amount of light emitted by the calculation circuit 3; 9 is a portion illuminated by the light emitted from the flash device; This is a display device that displays the difference in apex values of the portions that are not displayed (hereinafter referred to as step number difference).

Next, the operation of the photometric device of the present invention will be explained based on FIGS. 1, 2, and 3, as well as the timing control circuit 2 shown in FIG. 2. When the photometry start switch _S1 is closed, the terminal i becomes High at time _t0 in Fig. 3, and the pulse shown at i' in Fig. 3 is output from the one-shot circuit _OS1 in Fig. 2. Flip-flops F ₁ , F ₂ , F ₃ are set,
_F4 is reset, and counters _CO1 , _CO2 , and _CO3 are reset. When flip-flop _F1 is set, terminal C becomes High and terminal B becomes Low (Figure 3),
FETFT ₂ and FT ₃ are turned OFF and FT ₄ is turned ON. Furthermore, flip-flops F ₂ and F ₃ are set, the gates of AND circuits AN ₁ and AN ₂ are opened, and clock pulses from the clock input terminal CL are input to counters CO ₁ and CO ₂ for counting.
Note that the outputs of the counters CO ₁ and CO ₂ become High at the time of being reset, the terminals a and f become High, and therefore the FET (FT ₁ ) is turned on. Also,
At the same time as the switch _S1 is closed, the switch _S2 is also closed, and the flashlight emitting device (not shown) also starts emitting light.

By turning FET (FT ₁ ) ON and FT ₃ OFF,
The output of the operational amplifier OA ₁ is given to the base of the transistor BT ₁ , and the collector current of the transistor BT ₁ has a value corresponding to the output current of the photodetector PD.
This current is input to the logarithmic compression integration circuit composed of diodes D ₂ , D ₃ and capacitor C ₂ via transistor BT ₂ . At time _t1 in FIG. 3, the output of the counter _CO1 falls to low level, and the pulse from the one-shot circuit _OS2 is sent to the A-D converter 1 via the OR circuit _OR2 and terminal d, and the A- D conversion is started. When terminal a goes low, FT ₁ becomes
The transistors are turned off, and no current flows through the transistors BT ₁ and BT ₂ . Therefore, the charging voltage of the capacitor C ₂ corresponds to the logarithmic compression value of the amount of light received by the photodetector PD during flash emission, and this signal is applied to the FET (FT ₄ ).
The signal is input to the A-D converter 1 via. Also, in Figure 2, as the output of counter CO ₁ falls, the output of inverter IN ₁ rises, flip-flop F ₂ is reset, and the AND circuit is reset.
Since the gate of AN ₁ is closed, the counter CO ₁
counting is stopped, and thereafter terminal a remains low until switch _S1 is closed again.

When the AD conversion is completed (time _t2 in FIG. 3), a completion signal is output from the terminal e of the AD converter 1. This signal resets the flip-flop _F1 in FIG. 2, causing the terminal C to go low.
Terminal b becomes High. This allows the FET
(FT ₂ ), (FT ₃ ) are ON, FT ₄ is OFF, and A-
The output of the operational amplifier OA ₁ is directly input to the D converter 1, and the charge in the capacitor C ₂ is discharged.

At the time when the A-D conversion end signal is input from terminal e (t ₂ in Figure 3), the output f of counter CO ₂ is
Since it is High (Fig. 3 f), this signal is an AND circuit.
It is sent to terminal g via AN ₅ , which is input to latch circuit L ₂ , and the output data of AD converter 1 is latched into latch circuit L ₂ . Therefore, the photometric data during flash emission is latched in the latch circuit _L2 .

At the next time _t3 , the output f of the counter _CO2 falls to Low (Fig. 3f), and at this rise, a pulse is output from the one-shot circuit _OS3 , which is sent to the terminal d via the OR circuit _OR2 . Sent (3rd
Figure d) A-D conversion is started. At this time, as mentioned above, the FET (FT ₂ ) is ON and FT ₄ is OFF, so the A-D converter 1 receives only the intensity of the steady light from the low-pass filter composed of the resistor R ₁ and the capacitor C ₁ . A compatible signal is being input. Also,
When the output of counter CO ₂ falls, the output of inverter IN ₂ rises and flip-flop F ₃
is reset, the gate of the AND circuit _AN2 is closed, the counter _CO2 stops counting, and the output terminal f remains at Low.

When the A-D conversion of the stationary light ends at time _t4 in FIG. 3, an A-D conversion end signal is output from the terminal e (FIG. 3 e). At this time, the output of terminal f is Low.
Therefore, the output of inverter IN ₃ is High, and A-
The D conversion completion signal is output from the terminal h via the AND circuit _AN4 , and by this signal, data corresponding to the intensity of only the stationary light from the AD converter 1 is latched into the latch circuit _L1 . Therefore, at this point, data corresponding to the intensity Bva of only the steady light is latched in the latch circuit _L1 , and data corresponding to the light intensity Qvfa during flash emission is latched in the latch circuit _L2 . .

The pulse from the AND circuit AN ₄ is delayed for a certain period of time by the delay circuit DL ₁ (at time t ₅ in Fig. 3).
) is output to terminal j (Fig. 3 j). This signal causes the arithmetic circuit 3 (FIG. 1) to start operating. Furthermore, the flip-flop _F4 is set by the output of the delay circuit _DL1 , and the AND circuit is set.
The gate of AN ₃ is opened and counter CO ₃ starts counting. The counting time of the counter _CO3 is long enough for the calculation of the calculation circuit 3 to be completed and for the display to not flicker. The details of the arithmetic circuit 3 will be described later with reference to FIGS. 4 and 5.

The output pulse of the delay circuit DL ₁ is further delayed for a certain period of time by the delay circuit DL ₂ . By the way, flip-flop _F5 is the output of one-shot circuit _OS1.
Since the output is reset at i', the output becomes High, and the gate of the AND circuit _AN6 is opened and the delay circuit is activated.
The output pulse of DL ₂ is sent to the arithmetic circuit 3 via terminal k. This is used as a latch signal for latch circuit _L3 in arithmetic circuit 3, as will be described later.

The output terminal l of the counter CO ₃ is high from the start to the end of counting, and when the output of the counter CO ₃ falls to low at time t ₆ , the pulse from the one shot circuit OS ₄ is sent to the OR circuit OR ₂ , terminal d
The signal is sent to the A-D converter 1 via A-D conversion. Further, the pulse from the one-shot circuit OS ₄ is input to the OR circuit OR ₁ , and the flip-flop F ₄ and the counter CO ₃ are reset by the output of the OR circuit OR ₁ (at time t ₇ in FIG. 3).
No counting is done. Then, the A-D conversion end signal is input from the terminal e, the pulse from the delay circuit _DL1 is sent from the terminal j to the arithmetic circuit 3, and (at time _t8 in FIG. 3), the flip-flop
_F4 is set and counter _CO3 starts counting again. Also, flip-flop F ₅ is at time t ₆
Since it is set by the output of the one-shot circuit OS ₄ at the time of , the output is Low, the gate of the AND circuit AN ₆ is closed, and the output pulse of the delay circuit DL ₂ is not output from the terminal k. Thereafter, as described above, the A-D conversion latch, calculation, and display of the intensity of the stationary light are repeated, and the displayed value changes in accordance with the change in the stationary light.

FIG. 4 is a block diagram showing a specific example of the shutter speed priority system when the shutter speed is set first in the arithmetic circuit 3. latch circuit
The data from L ₂ is Qvfa, the amount of light received by flash only is Qvf, the intensity of steady light is Bva, the diode D ₂ ,
D ₃ , the integration time ( _third
If 2 ^-Tvc is the period between t ₀ and t ₁ in the figure, then there is the following relationship: 2 ^Qvf + 2 ^{Bva - Tvc} = 2 ^Qvfa ...(1). Further, the setting device 4 in FIG. 1 outputs the set exposure time Tvs, and the lighting/contrast setting device 5 outputs the set lighting contrast.
The contrast Δs and the set film sensitivity Sv from the film sensitivity setting device 6 are sent to the calculation circuit 3, respectively.
is input.

In FIG. 4, data Tvc corresponding to the apex value of integral time 2 ^-Tvc and data from latch circuit _L1 are input to subtraction circuit 16, and Bva-
The data of Tvc is calculated, and based on this data and the data Qvfa from the latch circuit _L2 , the subtraction circuit 1
In 7, the calculation Qvfa−(Bva−Tvc)=α...(2) is performed, and this data α is used for data conversion.
The ROM 18 converts the data into data corresponding to log ₂ (2〓-1). Then, the data from the subtraction circuit 16 (Bva-TVc) and the data from the ROM 18
log ₂ (2〓-1) is added by the adder circuit 19 to calculate Bva-Tvc+log ₂ (2〓-1)=Qvf (3).

The reason why the amount of light received due to flash only is calculated in equation (3) is that if Qvfa is removed from equations (1) and (2), 2 ^Qvf = 2 ^Bva-Tvc (2〓-1), and the log ₂ of both sides By taking , we obtain equation (3).

The data from the adder circuit 19 is latched in the latch circuit _L3 by a pulse from the terminal k, and thereafter the data is not changed until the photometry start switch _S1 is closed again and photometry at the time of flash emission is performed. This is because the intensity of the stationary light changes when performing A-D conversion between the intensity of the stationary light when the flash is emitted and the intensity of the stationary light alone, and the calculation result using equation (3) above is an incorrect value. This is because you get used to it.

Data Bva from the latch circuit _L1 and exposure time Tvs from the setting device 4 are input to the subtraction circuit 20, and Bva
-Tvs data is calculated, and this data and the lighting contrast Δs data from the setting device 5 are input to the adder circuit 21, and the calculation Δs+(Bva−Tvs)=Qvfx...(4) is performed, and the setting is performed. Data Qvfx of the amount of light emitted from only the flash necessary to obtain the lighting contrast Δs is calculated. This data and data Qvf of the amount of light emitted from the measured flash only from the latch circuit _L3 are input to the subtraction circuit 22 to calculate Qvfx−Qvf=Δf (5), which is displayed on the display (8). is displayed.
This value indicates how much the amount of flash light to be emitted during photometry is changed.

The lighting contrast data Δs from the setting device 5 is input to the data conversion ROM 23, and the data of log ₂ (2〓 ^s +1)=Δ . . . (6) is output. This data is displayed on display 9. The meaning of this data will be explained later. The data Bva−Tvs from the subtraction circuit 20 and
The data Δ from the ROM 23 is input to the adder circuit 24, and the data from the adder circuit 24 and the setting device 6
The film sensitivity Sv data from is added to the adder circuit 25.
is input. Therefore, the output of the adder circuit 25 is (BVa − Tvs) + log ₂ (1 + 2〓 ^s ) + Sv = Avx
...(7) The aperture value Avx is calculated and displayed on the display 7.

Next, we will explain the meaning of the data in formula (6) and the aperture value from formula (7).
Explain why Avx is calculated. Letting Qvt be the apex value of the total amount of light during flash photography, 2 ^Qvfx + ^{2 Bva-Tvs} = 2 ^Qvt ...(8) holds true. By the way, the lighting contrast Δs is Δs=Qvfx−(Bva−Tvs)...(4), and by eliminating Qvfx from equations (8) and (4), we can calculate both sides.
When log ₂ is taken, Qvt=(Bva−Tvs)+log ₂ (1+2〓 ^s )...(9) holds true. Therefore, Δ=log ₂ (1+2〓 ^s )=Qvt-(Bva-Tvs), which corresponds to the difference between the apex value of the overall light amount during flash photography and the apex value of the light amount of only the steady light. . Also, the reason why equation (7) holds true is that Qvt+Sv=Avx...(10) holds true.

FIG. 5 shows an embodiment of the arithmetic circuit when the aperture value Avs is set, and only the parts different from FIG. 4 are shown. The data Avs from the setter 26 and the data Sv from the setter 6 are sent to the subtraction circuit 28.
(Avs−Sv) is calculated. on the other hand,
Data Δs from setting device 5 is stored in ROM 2 for data conversion.
7, the data of log ₂ (1-2 ^- 〓 ^s ) is output, and this data and the data from the subtraction circuit 28 are input to the subtraction circuit 29, and Qvfx = (Avs - Sv) - log ₂ (1-2 ^- 〓 ^s ) ...(11) is calculated. The reason why equation (11) holds is that equation (8) and
From equation (10), 2 ^Qvfx + 2 ^Bva-Tv = 2 ^Avs-Sv ...(12), and by eliminating Bva-Tv from equations (12) and (4), we get 2 ^Qvfx (1-2 ^- 〓 ^s ) = 2 ^Avs-Sv , and by taking log ₂ on both sides, equation (11) is established. Further, the data Δs from the setting device 5 and the data Bva from the latch circuit _L1 are inputted to the adder circuit 30 and Bva
+Δs is calculated, and this data and data Qvfx from the subtraction circuit 29 are input to the subtraction circuit to obtain Tvx=Bva+Δs−Qvfx (4), which is displayed on the display 32. Further, the data Δf and Δ are calculated and displayed in the same manner as in FIG.

Although this embodiment is mainly shown only in block diagrams,
For example, this can be easily realized by using a commercially available microcomputer.

Effects As detailed in the above embodiment, in the photometry device for flash photography according to the present invention, the lighting contrast defined as the ratio of the amount of contribution of steady light to the amount of contribution to photography and the amount of contribution of flash light to photography can be set. The difference between the amount of contribution of flash light necessary for obtaining this lighting contrast to photography and the amount of contribution of flash light emitted in advance to photography obtained by the light emission amount metering means is calculated.

Therefore, for example, it is possible to know how much the amount of light emitted by the flash device to be used needs to be changed in order to take a picture with the lighting contrast desired by the photographer.

In other words, for example, when using a flash device with a variable amount of light emission, it is possible to emit light at the minimum amount at the time of metering before taking a picture, which prevents excess energy loss, and allows for arbitrary lighting. It will also be easier to take pictures with contrast.

[Brief explanation of drawings]

Fig. 1 is an overall circuit diagram showing an embodiment of the present invention, Fig. 2 is an example of a timing control circuit,
FIG. 3 is a time chart of this embodiment, FIG. 4 is an embodiment of the arithmetic circuit, and FIG. 5 is an embodiment of the arithmetic circuit when the aperture is set. PD, D ₁ , OA ₁ . . . Photometric circuit, D ₂ , D ₃ , C _{2 .} . . Logarithmic compression/integration circuit, 1 .

Claims (1)

[Scope of Claims] 1. A light emission amount photometer that measures the light emission of a flash device emitted in advance and outputs an electrical signal corresponding to the amount of contribution of the flash light to photography; Ambient light metering means that outputs an electrical signal corresponding to the amount of light received; Exposure value output means that outputs a signal corresponding to the exposure time; Defined as the ratio of the contribution of steady light to the contribution of flash light to photography. lighting/contrast output means for outputting a signal corresponding to the set lighting contrast; and lighting/contrast output means for outputting a signal corresponding to the lighting contrast set, and lighting/contrast output means for outputting a signal corresponding to the lighting contrast, an output signal of the ambient light metering means, and a signal corresponding to the exposure time. - A first calculation means for calculating a signal corresponding to the amount of contribution of flash light to photography necessary to obtain contrast, and an apex of the output signal of the light emission amount photometry means and the signal obtained by the first calculation means. 1. A photometry device for flash photography, comprising: second calculation means for calculating a difference in the system. 2. The light emission amount photometry means includes an integration means for obtaining an electric signal corresponding to the amount of light received by the light receiving element during the light emission operation of the flash device, and based on the signal from the integration means and the signal from the photometry means, and a third calculation means for calculating the amount of light received by the light receiving element from only the flash device during the light emission operation of the flash device, and the second calculation means calculates the amount of light received by the light receiving element only from the flash device, and the second calculation means calculates the amount of light received from the first and third calculation means. A photometric device for flash photography according to claim 1, characterized in that a difference is calculated. 3. A light emission amount metering means that measures the light emitted by the flash device emitted in advance and outputs an electrical signal corresponding to the amount of contribution of the flash to photography, and an exposure device that outputs a signal corresponding to the aperture value and a signal corresponding to the film sensitivity. a value output means; a lighting contrast output means for outputting a signal corresponding to a set lighting contrast defined as a ratio between the amount of contribution of steady light to the amount of contribution to photography and the amount of contribution of flash light to photography; and the above-mentioned lighting contrast. , a signal corresponding to the aperture value output from the exposure value output means, and a signal corresponding to the film sensitivity, which contribute to the flash photography necessary to obtain the above-mentioned lighting contrast so as to achieve appropriate exposure. a first calculation means for calculating a signal corresponding to the amount; and a second calculation means for calculating the difference in the apex system between the output signal of the luminescence amount photometry means and the signal obtained by the first calculation means. A photometry device for flash photography, characterized by comprising: 4. The light emission amount photometry means includes an integration means for obtaining an electrical signal corresponding to the amount of light received by the light receiving element during the light emission operation of the flash device, and based on the signal from the integration means and the signal from the photometry means, and a third calculation means for calculating the amount of light received by the light receiving element from only the flash device during the light emission operation of the flash device, and the second calculation means calculates the amount of light received by the light receiving element only from the flash device, and the second calculation means calculates the amount of light received from the first and third calculation means. A photometric device for flash photography according to claim 3, characterized in that a difference is calculated.