JPS5917544A - Electronic flash device - Google Patents

Abstract

PURPOSE:To prevent deficiency in the quantity of main light emission due to difference in light nature from the main emitted light, by providing a means of reducing the light measurement level of preliminary light emission using infrared light by bounce setting. CONSTITUTION:A switch SW1 is on in normal photography. A discharge tube 14 integrates 45 and 46 for the quantity of reflected light from a subject synchronously with preliminary light emission, and the integral level when the preliminary light emission is completed is discriminated 52-54 and stored M. Consequently, an integrating capacitor in the main light emission by a discharge tube 23 is selected and a diaphragm control signal is sent from a terminal 65 to a camera side. The switch SW1 is off in bounce photography and the quantity of preliminary light emission is reduced to compensate deficiency in the quantity of visible light during the main light emission by scattered infrared rays from bounce surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic flash device for camera photography, and in particular to an electronic flash device that determines an aperture value through pre-flash and sets the main flash light control level in accordance with the aperture value. It is about improvement. Note that the dimming level here refers to a predetermined value of the amount of light received at which the main light emission is stopped.

Electronic flash devices have already been proposed that determine the aperture of a photographic lens in response to the amount of reflected light received by pre-flash and perform main flash control at a dimming level corresponding to the aperture value. Also, in this type of electronic flash device, when the main flash is bounced, the pre-flash is also bounced at the same time, so that the aperture value set by the pre-flash always matches the flash control range of the main flash. Already proposed.

However, when infrared light is used for pre-flash in order to avoid dazzling the subject due to pre-flash, infrared light has a longer wavelength than visible light, so it is diffused on the reflective surface. Due to the nature of bouncing, the amount of light that reaches the subject is less than the main flash due to the degree of diffusion of the reflective surface. There was a problem that there was a discrepancy between the images and the amount of light was insufficient depending on the distance to the subject.

An object of the present invention is to solve the above-mentioned problems, and to prevent insufficient light quantity that may occur depending on the distance to the subject even during bounce shooting when infrared light is used for pre-flashing. Moreover, it is an object of the present invention to provide an electronic flash device that can be used in the same manner as in normal photographing.

In order to achieve this object, the present invention reduces the photometric level of reflected light caused by the pre-flash by setting the main light emitting section and the pre-flash light section in a direction in which the subject is indirectly irradiated by the irradiation direction changing means. The present invention is characterized in that a photometric level reduction means is provided to correct the difference in the amount of light loss on the bounce surface between the infrared light used for pre-light emission and the main light emission. Note that infrared light in the present invention also includes near-infrared light.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a perspective view of an electronic flash device that is an embodiment of the present invention, in which 1 is a first main body including a main light emitting section 2 and a pre-light emitting section 3, 4 is a second main body, and The main body 1 and the second main body 4 are rotatable at the connecting portion. 5 is the main light emitting part 2
The recesses provided on both sides are for attaching wide adapters, etc.

2 and 3 are side views including a partial sectional view of the electronic flash device according to the present invention, showing a cross section of the main light emitting section 2 and the pre-light emitting section 30, and the first light emitting section with respect to the second main body 4. A cross section of a switch Swl that is turned on and off in conjunction with the rotation of the main body 10 is shown. Figure 2 shows the state facing the subject, and since the push button 6 is pressed by the first body 1, the pair of elastic contact pieces 7 and 7' are in contact, and the amount of pre-flash light is not regulated. do not have.

FIG. 3 shows the state during bounce shooting, and since the push button 6 is not pressed by the first body 1, the pair of elastic contact pieces 7
．． 7' is released to reduce the amount of pre-emission light.

FIG. 4 shows the electrical circuit of the embodiment shown in FIGS. 1-3. 8 is a battery, 9 is a power switch, 10 is a DC-DC converter that boosts the DC voltage, 11.12 is a diode,
13 is a pre-flash capacitor for causing the pre-flash discharge tube 14 to emit light; 15 is a pre-flash increasing capacitor; 16 is formed by a resistor 17, a trigger transformer 18, a trigger capacitor 19, a trigger thyristor 20, and a resistor 21. A known trigger circuit 22 includes a resistor 24, a trigger capacitor 25, a trigger transformer 26, a trigger thyristor 27, and a resistor 28 for triggering the main flash discharge tube 23.
29 is a diode connected in series in the opposite direction to the flash discharge tube 23 for main light emission and connected in parallel to the inductor 30; 31.32 is a charging resistor for the commutating capacitor 33; 34 4 is a capacitor connected to the gate of the main thyristor 36 via a resistor 25; 37 is a main capacitor for the secondary shutter; 42 is a switch turned on by the first stage depression of the shutter release button;
3 is a synchro contact that turns on in synchronization with the shutter release, T1 is a pre-flash timer circuit, T2 is a main flash timer circuit, G is a timer circuit T, or a transistor 44 when a high level signal is input from T2. 45 is a light receiving element that receives reflected light from the subject; 46 is an integral capacitor charged by the photocurrent from the light receiving element 45; 47-51 are voltage dividing resistors; 52-
54 is a comparator, M is a memory circuit, 55-57 are transistors, 58-60 are integral capacitors, G! 61 is a gate circuit, 61 is a transistor that opens and closes according to the output of the gate circuit G2, 62 and 63 are voltage dividing resistors, 64 is a comparator that turns on the sub-thyristor 37, oP is an aperture control signal generation circuit, and 64 is a circuit that outputs an aperture control signal to the camera. This is a terminal that outputs vertically.

Next, the operation will be explained. First, select the subject □
The case of normal photography with direct irradiation will be explained. In this case, switch SW is on. When the power switch 9 is turned on, the DC-DC converter 10 charges the pre-flash capacitor 13 and the pre-flash increasing capacitor 15 with a voltage sufficient to cause the pre-flash discharge tube 14 to emit light. Next, when the switch 42 is turned on, each terminal t2, t of the timer circuit T becomes high level for a certain period of time. When the terminal t becomes high level, the known trigger circuit 1
6 operates, and the pre-emission flash discharge tube 14 starts emitting light. On the other hand, when a high level signal is input from terminal t2 to terminal t2 of gate circuit G, terminal t3 becomes low level, transistor 44 is turned off, and integration capacitor 46 can be charged. The light receiving element 45 converts the reflected light from the object into a current, and charges the integral capacitor 46. The charging voltage of the integral capacitor 46 is proportional to the integrated value of the reflected light from the subject. Voltage dividing resistor 4
The potentials of the partial pressure points a to C of 7 to 510 are determined corresponding to the short distance, middle distance, and long distance of the subject, respectively.

For example, if the distance is long, the charging voltage of the integrating capacitor 46 will be higher than the potential of the voltage dividing point C (
, the value is lower than the potential at the voltage dividing point S. Therefore, only the comparator 54 outputs a high level signal. If it is a medium distance, the comparators 53 and 54 will output a level signal, and if it is a short distance, the comparators 52 to 5 will output
All 4 output high level signals.

After a certain period of time, when the input from the terminal t of the pre-emission timer circuit T to the terminal t7 of the memory circuit M is reversed from the no level to the low level, the memory circuit M is connected to the terminal t1 at that time.
~t, is stored, and one of the transistors 55 to 57 is turned on based on the input level. For example, if the outputs of the comparators 52 to 54 are all at a high level, the transistor 55 is turned on and the short-range integrating capacitor 58 is selected. At the same time, transistors 55~
57, the aperture control signal generating circuit OP generates an aperture control signal, sends it to the camera side from a terminal 65, and changes the aperture of the lens according to the subject distance.

Next, when the synchro contact 43 is turned on, the terminals t2, t of the main light emission timer circuit T are at the no level for a certain period of time. When the terminal t becomes high level, a known trigger circuit 22 is activated and the main flash discharge tube 23 starts emitting light. On the other hand, a high level signal from the terminal t2 is sent to the gate circuit G.
When input to terminal tl of No. 2, terminal t becomes low level, turning off transistor 61. This allows one of the integrating capacitors 58 to 60 selected by the memory circuit M to receive power. When the flash from the main flash discharge tube 23 is reflected by the subject and received by the light receiving element 45, it is converted into a current and charged into one of the integrating capacitors 5°8 to 68 selected by the memory circuit M. Ru. The charging voltage of one of the integral capacitors 58 to 60 is applied to the voltage dividing resistor 6.
2. When the voltage becomes higher than the 630 dividing point voltage, the Pumbaleta 6
4 outputs a high-level signal to the sub-thyristor 37, the sub-thyristor 37 is turned on, and the main thyristor 36 is reverse biased by the charge of the commutating capacitor 33.
The main thyristor 36 is turned off, and the flash discharge tube 23 for main light emission is turned off.
0 Stops light emission.

Note that when a high-level signal from the terminal t of the main light emission timer circuit T is input to the gate circuit GI, the transistor 44 is turned off and the integral capacitor 46 is charged by the current flowing through the light receiving element 45. Since the capacitance of the integration capacitor 46 is considerably smaller than the capacitance of the integration capacitors 58 to 60, the loss due to charging of the integration capacitor 46 can be ignored.

When a subject is to be indirectly irradiated, the switch SW+ is turned off (the state shown in FIG. 3), and the amount of preliminary light emission is reduced. This is because there is little scattering of infrared light on the bounce surface, so the amount of light on the subject surface does not decrease and can be made to correspond to the main light emission amount. Hereinafter, the operation is the same as when the switch SW is turned off, so a description thereof will be omitted.

In FIG. 4, by turning off the switch SW1 during bounce shooting, the pre-flash increasing capacitor 15 is disconnected and the pre-flash metering level is reduced, but as shown by the dotted line in FIG. By providing a switch SW2 in parallel with the voltage dividing resistor 47 and turning on the switch SW2 during bounce shooting, the comparator 52
It may be reduced.

5 to 8 show other embodiments of the invention.

In this embodiment, the photometry level of the pre-flash is reduced by placing a filter or the like in front of the light-receiving element of the pre-flash during bounce photography. Parts similar to those shown in FIGS. 1-4 are designated by the same reference numerals. As shown in FIG. 5, the front surface of the second main body 4 is provided with a light receiving window 67 for pre-light emission in addition to the light receiving window 66 for main light emission.

FIG. 6 shows a normal photographing state in which the subject is directly irradiated. The pressing pin 68 compresses the spring 69 and is pushed downward by the first body 1, and the rod 7o formed integrally with the pressing pin 68 is also guided by the guide 71 and lowered. The filter 72 attached to the lower end of the guide 71 is removed from the front surface of the pre-emission light receiving element 73 and moves downward, so that it passes through the front surface of the pre-emission light receiving element 73. The rod 70 is pushed up by the spring 69, and the filter 72 is placed at position 12 in front of the light receiving element 73 for pre-emission, reducing the amount of light received for pre-emission.

FIG. 8 shows the electrical circuit. A light receiving element 75 for main light emission and a light receiving element 73 for pre-emission are provided separately. The capacitance of the pre-emission capacitor 76 is equal to the sum of the capacitances of the pre-emission capacitor 13 and the pre-emission increasing capacitor 15 shown in FIG. The circuit shown in FIG. 8 operates in the same manner as the circuit shown in FIG. 4, so a description of its operation will be omitted.

In the illustrated embodiment, the first body 1 rotatably connected to the second body 4 corresponds to the irradiation direction changing means of the present invention, and is connected to the memory circuit M in FIG. 4 or FIG. Circuit up to the right comparator 64 and light amount control circuit 40
corresponds to the control means of the present invention, and the switch SW and the capacitor 15 for pre-emission increase, or the switch SW2, or the filter moving mechanism from the filter 72 and the press pin 68 to the transparent portion 74 reduce the photometry level of the present invention. It corresponds to the means.

Note that the photometric level reducing means is not limited to the illustrated embodiment (for example, it may be switched to a pre-emission integrating capacitor with a large capacity in response to a change in the irradiation direction).

As described above, according to the present invention, the main light emitting section and the pre-emission section are set in a direction in which the subject is indirectly irradiated by the irradiation direction changing means, so that the photometry level of the light reflected by the pre-emission can be adjusted. A photometry level reduction means is provided to compensate for the difference in light amount loss on the bounce surface between the infrared light used for pre-flash and the main light, so when infrared light is used for pre-flash, Even during bounce photography, it is possible to prevent a lack of light intensity that could occur depending on the distance to the subject, and the effect is that it can be used with the same operations as during normal photography.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an electronic flash device which is an embodiment of the present invention, Fig. 2 is a partially sectional side view showing its normal shooting state, and Fig. 3 is a partially sectional side view showing its bounce shooting state. Figures 4 and 4 are the same (electrical circuit diagram, Figure 5 is a perspective view showing another embodiment of the present invention, Figure 6 is a partially sectional side view showing its normal photographing state, and Figure 7 is its bounce The partially sectional side view showing the photographing state and FIG. 8 are the same (electrical circuit diagrams). 1... first main body, 2... main light emitting section, 3... pre-emitting section, 4-.・Second main body, SW,... switch,
13...-capacitor for pre-emission, 14---capacitor for pre-emission 41...-main capacitor, 45--light receiving element, 5
5-57...transistor, 58-60--integrating capacitor, 64--comparator, 72--filter,
73-... Light receiving element for pre-emission, SW,... Switch, M... Memory circuit, OP... Aperture control signal generation circuit. Patent applicant Canon Co., Ltd. Representative Minoru Hitonakamura

Claims (1)

[Claims] L A main light emitting section, a pre-emission section that emits infrared light, an irradiation direction changing means that simultaneously changes the irradiation direction of the main light emitting section and the pre-emission section, and a light metering level corresponding to the light reflected by the pre-emission, In an electronic flash device comprising a control means for determining an aperture value of a photographing lens and controlling light emission of a main light emitting section at a dimming level corresponding to the aperture value, the subject is indirectly irradiated by the irradiation direction changing means. 1. An electronic flash device comprising: a photometric level reducing means for reducing the photometric level by setting the photometric level in a direction.