JPH04335622A - Strobe controller - Google Patents

Abstract

PURPOSE:To realize efficient strobe control by reducing red-eye phenomena and also varying an emitting light quantity according to photographic conditions. CONSTITUTION:This strobe controller is provided with a stroboscopic light emitting part 7D, a main capacitor 29 which changes the emitting light quantity of the stroboscopic light emitting part 7D and a subcapacitor 28. In a close distance within the prescribed distance, only the subcapacitor 28 is discharged, thereby controlling the emitting light quantity corresponding to the distance. In photographing where the red-eye phenomenon is prevented, only the subcapacitor 28 is discharged in advance, and the emitting light quantity is controlled so as to meet the above-mentioned distance after the subcapacitor 28 is recharged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe control device, and more particularly to a control device for controlling the amount of light emitted by a strobe according to various photographic conditions.

0002

[Prior Art] In camera flash photography, a flash matic system is generally used to prevent differences in the effects of strobe light emission due to differences in distance.
This allows the strobe to emit light when the shutter has a large aperture for long distance shots, and when the shutter has a small aperture for short distance shots. This is an attempt to adjust the but,
Even with this flash-matic method, the larger guide number is used at short distances. (GNo. . . . a value indicating the amount of light from the light source) when performing strobe light emission, there is a problem that the amount of light emitted increases even if the aperture has the minimum aperture.

For example, guide No. 10 strobes to 0
．． When used at a short distance of 3 m, the aperture F value for proper exposure is 33.3, but control becomes difficult at this aperture F value. Furthermore, since the aperture diameter becomes extremely small, the adverse effects of diffraction will also occur. Therefore, in the past, a large strobe and a small strobe were installed, and the smaller strobe was used for close-up photography, or two capacitors of different capacitances were connected to the xenon tube used for strobe light, and for close-up photography, the smaller strobe was used to fire light. An auto-variable (variable guide number) strobe is used that discharges only a small-capacity capacitor, and at medium and long distances, both large-capacity and small-capacity capacitors emit light at the same time. According to this, even in close-range photography, it is possible to take a photograph in an appropriate exposure state without setting the aperture to the minimum aperture.

0004

[Problems to be Solved by the Invention] By the way, in conventional strobe photography, the subject's eyes appear red.
There is a problem in that a so-called red-eye phenomenon occurs. This red-eye phenomenon is a phenomenon in which when a strobe is used on a human or animal subject, light enters the eyeball through the pupil and is reflected from the blood vessels within the eyeball, causing the eye itself to appear red. Therefore, in order to prevent this, it is possible to reduce the pupil diameter to reduce the incidence of strobe light into the eyeball. For example, before taking a picture, a strobe is fired, the pupil diameter is made small, and then the actual shooting is performed. A method to enter is proposed.

However, in the above case, it would be wasteful to provide a new control circuit and light emitting unit just to prevent the red-eye phenomenon, and if the device is integrated with the device that controls the amount of light emitted according to the distance described above, You can get a device that is easy to use.

The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the red-eye phenomenon, and
An object of the present invention is to provide a strobe control device that can vary the amount of light emitted according to photographing conditions.

[0007]

[Means for Solving the Problems] In order to achieve the above object, a strobe control device according to the present invention includes a strobe light emitting section, a main capacitor and a sub capacitor that cause the strobe light emitting section to emit light by changing the amount of light emitted. At short distances within a predetermined distance, only the sub-capacitor is discharged to control the amount of light emitted according to the distance, and for red-eye prevention photography, only the sub-capacitor is discharged in advance and this sub-capacitor is After recharging, the light emission amount is controlled according to the distance described above.

[0008]

[Function] According to the above configuration, for example, when the subject is close, the strobe will fire by discharging only the sub-capacitor, and proper exposure can be obtained without minimizing the shutter aperture diameter. is prevented from being overexposed. Further, when the subject is far away and the subject is dark, the strobe will emit light due to the discharge of both the main capacitor and the sub-capacitor, and even in this case, it is possible to take a photograph with proper exposure.

On the other hand, when the red-eye prevention mode is selected, a small amount of light is emitted by discharging only the sub-capacitor in advance, thereby reducing the pupil diameter of the subject's eye. Then, this sub-capacitor is recharged for about 1 second, for example, and thereafter the amount of light emitted by the strobe is variably controlled according to the distance by the above-mentioned light amount control.

0010

[Embodiment] Fig. 1 shows the circuit configuration of a strobe control device according to the embodiment, Fig. 2 shows the external structure of the camera, and Fig. 3 shows the entire control circuit of the camera. The configuration is shown. First, in FIG. 2(a), a lens barrel 3 having a photographing lens 2 is provided on the front of a camera body (main body) 1.
are arranged to move forward and backward, and are provided with a finder 4, a light projection window 5a for autofocus (AF), a light reception window 5b for AF, and a CdS (cadmium sulfide) light reception window 6 for an automatic exposure meter (AE). A strobe light emitting unit 7D containing a xenon tube or the like is disposed on the front surface.

On the top surface of the camera body 1, there are a main switch 8, a shutter button 9, and a strobe mode switching button 1.
0 is placed. This strobe mode switching button 10
As shown in FIG. 2(b), the knob 10a is in the groove 1.
It has a structure that slides within 0b, and low-brightness automatic light emission (A
auto), forced flash (ON) for daytime synchronization, flash off (OFF), forced flash with pre-flash to prevent red-eye (PR)
You can switch between four strobe modes (E, ON).

In FIG. 3, a CPU (central processing unit) 12 that controls the entire camera operation includes a strobe control unit 7, a shutter 11, an autofocus (AF) unit 13, and a photometry unit for performing automatic exposure (AE). 14 to control these. The photometry section 14 has a CdS (cadmium sulfide) element 15 which is a photoelectric conversion element placed behind the AE light receiving window 6.
The subject brightness is detected by the dS element 15. Further, a motor drive section 16 is connected to the CPU 12, and this motor drive section 16 drives a film winding motor 17.
to drive and control. Further, a sensitivity reader 18 is connected to the CPU 12, and this sensitivity reader 18 can read the ISO (International Standardization Standard) sensitivity of the film using the DX code added on the cartridge.

According to the above circuit configuration, when the shutter button 9 is pressed, the first stage switch S1 is turned on, and the CPU 12 is turned on.
First, the AF unit 13 is driven, and infrared light is emitted from the AF light projection window 5a, and the light reflected from the subject is received by the AF light reception window 5b. Therefore, the subject distance is measured by this AF section 13,
This distance information is input to the CPU 12. Next, the CPU
12 drives the photometry section 14, and the subject brightness is measured by the CdS element 15 arranged behind the AE light receiving window 6, and this brightness information is input to the CPU 12. Further, the strobe mode information set with the strobe mode switching button 10 is input to the CPU 12.
Furthermore, the IS of the film read by the sensitivity reading section 18
O sensitivity (DX code) information is input.

When the shutter button 9 is further pressed, the second stage switch S2 is turned on, and the CPU drives and controls the shutter 11 based on the input information, so that the subject image is recorded on the film. Being photographed. At this time, the strobe control section 7 is driven based on the setting information of the strobe mode switching button 9 and the subject brightness measured by the photometry section 14, and strobe light is emitted as necessary. When photographing is completed, the motor drive section 16 drives the film winding motor 17, thereby advancing the film by one frame.

In FIG. 1, the strobe control section 7 includes a boost section 7A, an auto cut section 7B, a trigger section 7C, and a light emitting section 7.
D, the booster section 7A is provided with a transistor 20, an oscillation transistor 21, an oscillation transformer 22, etc.
When the output of the terminal FCT of the CPU 12 becomes Low level, the oscillation transistor 21 is turned on and charging is performed.On the other hand, when the output of the terminal FCT becomes High level and the output of the terminal FINH becomes Low level,
Since the transistor 20 is turned on, charging is stopped.

The auto-cut section 7B is provided with a Zener diode 23 and a transistor 24. The Zener diode 23 is turned on when the charging voltage reaches a voltage sufficient to ensure the amount of light, and at the same time the transistor 24 is turned on.
is turned on, so the input to the FR terminal of CPU12 is Low.
When the CPU 12 detects this low level input, the output of the terminal FINH is set to low level and charging is stopped.

The trigger section 7C includes an SCR element 25.
, a trigger coil 26 are provided, and the light emitting section 7D is provided with a xenon tube 27 as a light emitting element, a small capacitance sub capacitor 28, a large capacitance main capacitor 29, a transistor 30, an SCR element 31, and the like. Then, when the CPU 12 sets the output of the terminal FT to High level, the trigger coil 26 generates a high voltage due to the ON operation of the SCR element 25, which causes the xenon tube 27 to emit light. Here, if the light emitting operation is performed only by the sub-capacitor 28, the CPU 1
The output of the second terminal PREO is set to High level, the transistor 30 is turned on, and the gate of the SCR element 31 is set to Low level, thereby stopping the discharge of the main capacitor 29. On the other hand, when discharging both the sub capacitor 28 and the main capacitor 29, the output of the terminal PREO of the CPU 12 is set to L.
ow level and Low at the gate of transistor 30.
It is sufficient to release the w level fixation, so that when the trigger coil 26 is triggered, the sub capacitor 28 is discharged, and at the same time, the SCR element 31 is turned on and the main capacitor 29 is also discharged. Note that the power source 33 is provided as a power source for the entire camera.

The embodiment has the above configuration, and its operation will be explained below based on FIGS. 4 and 5. FIG. 4 shows low-intensity automatic light emission (
The operation when the shutter button 9 is set to "Auto" is shown, and first, in step 101, the first stage switch S1 of the shutter button 9 is turned on.
is turned on, in step 102 the CPU 12
If the FCT of is at a low level, it is set to a high level and the output of the FINH terminal is set to a low level, thereby inhibiting charging, preventing strobe noise, and stabilizing the power supply. In the next step 103, distance measurement is performed in the AF section 13, and in step 104
Then, photometry is performed by the photometry section 14 and the CdS element 15, and the process moves to the next step 105.

In this step 105, the strobe mode is confirmed, and if the strobe mode is set to other than auto mode ("N").
), the process moves to another operation flow, and when the auto mode is selected ("Y"), the process moves to step 106, where it is determined whether the current state is a low brightness state. If the brightness is not in the low brightness state, the process moves to another operation flow, and if the brightness is in the low brightness state, the process moves to step 107. In other words, in auto mode, it is determined whether or not the brightness is low based on the subject brightness, photometry information, and film sensitivity information (DX code), and if the brightness is low, preparations are automatically made for strobe firing. .

[0020] In the next step 107, the completion state of charging is confirmed, and when it is "N", the process moves to step 108, and after determining whether the switch S1 is in the off state, in step 109, charging is completed. Start. on the other hand,
When "Y" in step 107, that is, when charging has been completed, the process moves to step 110, and it is determined whether or not the switch S2 for starting the release is turned on. The process moves to step 111.

In this step 111, the subject distance is 0.
．． It is determined whether the distance is 7 m or less, and if "N", the process moves to step 113, and if "Y", the process moves to step 1.
12 and set the output of the PREO terminal of CPU 12 to Hi.
gh level and prohibits the main capacitor 29 from emitting light. That is, in the embodiment, 0.7 m is set as the distance over which strobe light is emitted by discharging only the sub-capacitor 28. For example, the strobe guide No. by the sub-capacitor 28. 3. Strobe guide No. by both sub capacitor 28 and main capacitor 29. 10
Assuming that the closest shooting distance of the camera is 0.3 m, the optimum aperture value F of the lens aperture using the flash-matic method of the program shutter is 0.3 m above, guide No. = 3, F1 = 3/0.3 (m)
=10 Guide No. =10, then F2 =10/0.
3(m)=33.3. Generally, the aperture value F that can be controlled by the flash matic method of the shutter 11 is about 16 to 22, and therefore cannot be controlled at the aperture value F at the distance of 0.3 m. In this case, if the aperture value F of the lens aperture is 3.5, an appropriate amount of light can be obtained by performing strobe light emission using only the sub-condenser 28.

[0022] Also, at 0.7m, guide No. 3, F3 = 3/0.7 (m) = 4
．． 3 Guide No. 10, F4 = 10/0.7(
m)=14.3. Therefore, in this case, using both the sub capacitor 28 and the main capacitor 29, the guide No. 10, the minimum aperture value F is 14.3, which is a value that can be controlled with sufficient precision, so the setting conditions for the sub capacitor 28 and main capacitor 29 should be as follows. . (0.3m) ~ 0.7m ... Sub capacitor (Guide No. 3) 0.7 m ~ (∞) ... Sub + main capacitor (Guide No. 10)

From the above, in step 111, 0.
When the distance is 7 m or less, the P of the CPU 12 is set at step 112.
The discharge of the main capacitor 29 is prevented by setting the output 125 of the REO terminal to High level, turning on the transistor 30 of the light emitting section 7D, and setting the gate of the SCR element 31 to Low level. And next step 11
In step 3, the lens is set at a predetermined position by autofocus control by the AF section 13, and in step 14, the sectors of the shutter are gradually opened. When this sector gradually opens, guide no. When the aperture value of the flash matic method calculated from the subject distance and the sector aperture become equal, the CPU 12's FT
A pulse-like signal is applied to the output of the terminal, which causes the xenon tube 27 to emit light by discharging the sub-capacitor 28 (step 115).

After the strobe light emission in step 115 is completed, the sector is closed in step 116, and the PREO terminal is turned off in step 117. Then, in step 118, the lens is returned to a predetermined position, and in the next step 119, the film is advanced by one frame.Then, in step 120, the sub-condenser 28 is charged again, and the next Ready for shooting.

On the other hand, if it is detected in step 111 that the distance is 0.7 m or more, the process proceeds to step 113 without passing through step 112. Therefore, when a pulse signal is applied to the output of the terminal FT of the CPU 12, the sub As the capacitor 28 discharges, the gate voltage of the SCR element 31 increases and becomes conductive, so that the main capacitor 29
As a result, both capacitors 28 and 29 will emit strobe light.

FIG. 5 shows the operation when the strobe mode switching button 10 is set to forced flash with pre-flash for red-eye prevention (PRE ON), and step 201 is performed.
-204 perform the same operations as in FIG. 4, but in the next operation step 205, it is determined whether or not the red eye prevention mode (PRE ON) has been selected, and if "Y", step 2 is performed.
06, the charging completion state is checked in the same way as in the case of FIG. Determine whether or not is turned on. When switch S2 is turned on, first the output of terminal PREO of CPU12 is set to High.
The SCR element 31 in the light emitting section 7D is brought into a non-conductive state to prohibit discharging of the main capacitor 29, and the process proceeds to the next step 211. In this step 211,
Since a pulse signal is supplied to the output of the terminal FT of the CPU 12 to discharge only the sub-capacitor 28, pre-stroboscopic light emission is performed. In this case, the shutter sector is not yet opened and photography is not performed, and the discharge of only the sub-capacitor 28 causes the guide No. 3 strobe light emission will be performed, and this pre-light emission can make the pupils of the eyes of the human or animal subject smaller.

[0027] It takes a little less than 1 second for the pupil to react in the strobe pre-flash, so in order to make effective use of this time, in the next step 212, a 0.8 second timer is started, and step 212 is started. 213 is the terminal F of the CPU.
The sub-capacitor 28 is charged by setting the output of INH to High level and the output of terminal FCT to Low level.

When charging is completed in the above step 213, it is detected in the next step 214 whether or not the input to the terminal FR of the CPU 12 has become a low level, and if it is "Y", the process moves to step 215 and the charging stop. In the next step 216, it is determined whether 0.8 seconds have passed since the timer was started in step 212, and "
Y'', the process moves to step 217, and a photographing operation including a strobe light emission operation is started.

The operations from step 217 to step 226 are exactly the same as the operations from step 111 to step 120 in FIG. 4, and the object distance is 0.
When the subject distance is 7 m or less, strobe light is emitted by discharging only the sub-capacitor 28, and when the subject distance is 0.7 m or more, strobe light is emitted by both the sub-capacitor 28 and the main capacitor 29. In this way, even when the red-eye prevention mode is set, pre-flash flash is performed to prevent red-eye, and in subsequent actual photography, the amount of light emission is controlled in accordance with the distance.

In the above embodiment, the discharge control of the sub-capacitor 28 and the main capacitor 29 is performed based on the object distance of 0.7 m, but the setting of this object distance can be changed as appropriate. Further, when the subject distance is 0.7 m or more, the sub capacitor 28 and the main capacitor 29 are always discharged, but the invention is not limited to this. For example, only the sub capacitor 28, only the main capacitor 29, or the sub capacitor 28 and the main capacitor 29
It is also possible to control the amount of light emitted in three stages in this order.

[0031]

[Effects of the Invention] As explained above, according to the present invention,
In addition to controlling the amount of light emitted according to the distance, in red-eye prevention shooting, only the sub-capacitor is first discharged, and after this sub-capacitor is recharged, the amount of emitted light is controlled according to the distance, so the sub-capacitor and the main capacitor are By using a strobe light in combination with this, it is possible to effectively reduce the red-eye phenomenon, and it is also possible to obtain photographs with appropriate exposure from close to far distances by adjusting the amount of light emitted according to the shooting conditions. Therefore, there is an advantage that strobe control can be performed efficiently.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a strobe control device according to an embodiment of the present invention.

FIG. 2 is an external configuration diagram of the camera of the example, and FIG.
1 is a perspective view of the external appearance, and FIG. 7B is a diagram showing details of the strobe mode switching button.

FIG. 3 is a block diagram showing the overall configuration of the control circuit of the camera according to the embodiment.

FIG. 4 is a flowchart showing the operation when auto mode is selected in the embodiment.

FIG. 5 is a flowchart showing the operation when red-eye prevention mode is selected in the embodiment.

[Explanation of symbols]

1... Camera body, 7... Strobe control section, 7A... Boosting section, 7B... Auto cut section, 7
C... Trigger section, 7D... Light emitting section, 10
... Strobe mode switching button, 12...C
PU, 13...AF (autofocus) section, 14
... Photometry section, 20, 24, 30 ... Transistor, 25, 31
... SCR element, 27 ... Xenon tube, 28 ... Sub capacitor, 29 ... Main capacitor.

Claims (1)

[Claims] [Claim 1] A strobe light emitting section, a main capacitor and a sub capacitor that cause the strobe light emitting section to emit light by changing the amount of light emitted, and only the sub capacitor is discharged at a short distance within a predetermined distance. In addition to controlling the amount of light emitted according to the distance, red-eye prevention shooting
A strobe control device that discharges only a sub-capacitor in advance, recharges the sub-capacitor, and then controls the amount of light emitted according to the distance described above.