JPH0522923Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field of the invention) The present invention is an electronic flash device having a plurality of flash discharge tubes, and in particular, an electronic flash device that is controlled so that a constant amount of light is always obtained regardless of the number of flash discharge tubes being emitted. This invention relates to a fixed-intensity electronic flash device.

(Background of the invention) An electronic flash device having a plurality of flash discharge tubes was proposed in Publication of Utility Model Publication No. 37-8161. recent years,
2. Description of the Related Art There is a product in which a plurality of flash discharge tubes selectively emit light in a flash device for close-up photography and the like to vary the lighting effect. However, with devices like this that selectively emit light from multiple flash discharge tubes, although it is possible to emit full light, it is not possible to selectively emit a constant amount of light by switching the guide number to several stages. I couldn't do it. Three methods have been proposed for controlling a constant amount of light in a flash device. The first method is to obtain a constant amount of light by detecting the voltage drop of the main capacitor during light emission, which is proposed in Japanese Patent Application Laid-Open No. 52-88332. The second is special public service in 1977-
A method proposed in 21048 that obtains a constant amount of light by detecting the current flowing through the flash discharge tube when it emits light. The third method is a method proposed in Utility Model Application Laid-Open No. 49-117839, in which a light receiving element receives the light emitted from a flash discharge tube during light emission and integrates the amount of light to obtain a constant amount of light.

However, when selectively emitting light from multiple flash discharge tubes, the relationship between the discharge charge of the main capacitor and the amount of light changes greatly when the number of flash discharge tubes changes, so the first and second methods are not accurate. I can't control it. In addition, the third method detects the light emission itself from the flash discharge tube, so accurate detection is possible, but when multiple flash discharge tubes emit light at random, it is necessary to detect each tube using the detection light receiving means. There are difficulties in how to detect the amount of light emitted by the sensor and how to control it using the detected output, so it has not yet been commercialized.

(Objective of the invention) The object of the present invention is to solve these drawbacks and provide a constant light amount electronic flash device that can always obtain a constant amount of light no matter how many flash discharge tubes are used to emit light.

(Summary of the invention) This invention monitors the light emission of each of multiple flash discharge tubes connected in parallel using a light receiving element, and can always control the light amount at a constant level even if the number of flash discharge tubes emitting light changes. The technical point is to provide an optical or electrical adjustment means for adjusting the conversion gain of the light emission intensity of each flash discharge tube into an electric signal of the light receiving element to be equal.

(Embodiment) FIG. 1 is a schematic diagram showing one embodiment of the present invention, which is a flash device for close-up photography that is attached to the front surface of a photographic lens of a camera. Two flash discharge tubes Xe1 and Xe2 arranged facing each other, a light receiving element 11 for monitoring the light emission of these flash discharge tubes, and a hood and holder 103 having a wall that does not transmit light to accommodate the light receiving element 11. , a reflection block 104 (formed in a triangular prism) that guides the light from the discharge tubes Xe1 and Xe2 to the light receiving element 11 by reflecting it on the left and right surfaces, respectively, a reflecting mirror 101 that reflects the light from the discharge tubes; It consists of a printed board 102 that houses the example electric circuit (FIG. 2), and a case 105 that houses these members. A sectional view taken along line A-A' in FIG. 1 is shown in FIG. Identical parts are indicated by the same numbers.

A part of the light emitted from the discharge tube is reflected within the cavity separated by the reflecting mirror 101 and the protective panel 107, and after being reflected from the left and right surfaces of the reflecting block 104, a third light is sent to the light receiving element 11 in the holder 103. It is guided as shown in figure l. As shown in FIG. 3, the reflecting block 104 is fixed to the reflecting mirror 101 with screws 108. Case 10 through which screw 108 penetrates
5. The hole of the reflecting mirror 101 has an oval shape. A rotating shaft 104a integrated with the reflecting block 104 fits into a hole formed in the reflecting mirror 101, and the reflecting block 104 can swing left and right to some extent around the shaft 104a. It is now possible to adjust the relative positions. That is, the left and right discharge tubes Xe1,
This is a mechanism for guiding the light from Xe2 to the light receiving element 11 in a well-balanced manner. Further, 106 is a dustproof window, and the amount of light may be roughly adjusted using an ND filter or the like. The adjustment and operation of reflection block 104 will be discussed in the discussion of FIG. 2 below.

FIG. 2 is an electrical circuit of the embodiment shown in FIG. In the figure, 1 is a DC power supply, SW1 is a power switch, 2 is a well-known DC-DC converter, 3 is a rectifier diode, 4 is a main capacitor for storing the luminous energy of the discharge tube, and 6 is a trigger coil. It is combined with a trigger coil 6, a resistor 5, and a capacitor 7 to constitute a well-known trigger circuit. The main thyristor SCR1 is connected in series to a parallel body of discharge tubes Xe1 and Xe2, and the commutating thyristor SCR2 is connected in parallel to the main thyristor SCR1. 10
is a commutating capacitor and is charged via resistors 8 and 9. Discharge tubes Xe1, Xe2, light receiving element 11
is the same as that in Figure 1. The light receiving element 11, the integrating capacitor 12, the comparator 13, and the reference power source Vref are a well-known dimming circuit. Switch SW
2. SW3 selects the discharge tube to emit light, and adjusts the output of trigger coil 6 and each discharge tube Xe1, Xe.
The electrical connection with the trigger electrode of No. 2 is opened and closed. When the switch SW2 is closed, the discharge tube Xe2 becomes capable of emitting light, and when the switch SW2 is open, no trigger voltage is applied to the trigger electrode of the discharge tube Xe2, and the discharge tube Xe2 becomes unable to emit light. The switch SW3 also has a similar effect on the discharge tube Xe1.

When the power switch SW1 is closed, the DC-DC converter 2 is activated, charging the main capacitor 4 with luminous energy and simultaneously charging the trigger capacitor 7,
The commutating capacitor 10 is charged to a predetermined state. Although not shown in the figure, when the X contact closes due to the camera release operation, the main thyristor SCR1
A positive voltage is applied to the gate of the main thyristor
The SCR1 becomes conductive, and the discharge tubes Xe1 and Xe2 selected by the switches SW2 and SW3 start emitting light as is well known. Light from each discharge tube is guided to the light emitting element 11 as described above. The charging current I _L , which is the output current of the light receiving element 11, charges the integrating capacitor 12, and the comparator 13 outputs a positive signal when the charging voltage of the integrating capacitor 12 reaches a reference voltage preset by the reference power supply Vref. The voltage is transmitted to the gate of commutating thyristor SCR2. As a result, the commutating thyristor SCR2 becomes conductive, and one discharge tube Xe1 is selected by a well-known commutating operation.
Or stop Xe2 or both. The above is similar to the conventional series control type flash device.

If it is a flash device that constantly emits light from the two discharge tubes Xe1 and Xe2, it is not necessary to adjust the balance of incidence of light from both discharge tubes on the light receiving element 11 using the reflection block 104. Therefore, when only one of the discharge tubes Xe1 or Xe2 is made to emit light, or when both of the discharge tubes are made to emit light, in order to control the light at a constant amount in either case, the following adjustment is made.

1 Open the switch SW2 and close the switch SW3 to make only the discharge tube Xe1 emit light, and measure the amount of light actually received by the subject using a flash meter (light amount measuring device). The amount of light is determined by the discharge tube
1, the light emission amount is B1.

2 Open the switch SW3 and close the switch SW2 to cause only the discharge tube Xe2 to emit light, and measure the amount of light using the flash meter in the same manner as described above.
The amount of light is defined as the amount of light emitted by the discharge tube Xe2 B2.

3. The light receiving element 1 is controlled by the reflection block 104 so that when the discharge tubes Xe1 and Xe2 are made to emit light one by one, the light emission amounts B1 and B2 become approximately the same value.
The output current I _L of the light-receiving element 11 is adjusted by adjusting the luminous flux from the discharge tubes Xe1 and Xe2 received by the discharge tube
1. Xe2 is stopped. For example, discharge tube
If the luminous intensities of Xe1 and Xe2 are different, try guiding less of the luminous flux from the discharge tube with weak luminous intensity to the light receiving element 11 (on the contrary, more luminous flux from the discharge tube with strong luminous intensity will be guided to the light receiving element). If you adjust the reflection block 104 so that the
The discharge tube with strong emission intensity stops quickly and the desired amount of light (guide number) at the subject can be obtained.

When the position of the reflection block 104 is adjusted so that the light emission amounts B1 and B2 are approximately the same as described above, each luminous flux measured on the subject side irradiated by each discharge tube Xe1, Xe2 and the light receiving element 11 The ratio of the luminous fluxes of the discharge tubes Xe1 and Xe2, which are photoelectrically converted by , ie, the conversion gain, is approximately equal for the discharge tubes Xe1 and Xe2. Therefore, after the adjustment is made in this way, a constant amount of light (that is, a desired guide number) can always be obtained whether the discharge tubes Xe1 and Xe2 are made to emit light individually or both are made to emit light at the same time. When setting the desired guide number, the reference voltage of the comparator 13 is
All you have to do is adjust Vref and set it to the desired level that corresponds to the guide number.

It should be noted that the present invention is not limited to the embodiments described above and can be modified as appropriate. For example, it is also possible to fix the reflection block 104 and configure the light receiving element 11 side to be adjustable. Furthermore, by removing the reflection block 104 and receiving the light reflected from the inner surface of the reflecting mirror 101 by the light receiving element 11, and changing the position or angle of the light receiving element 11, the conversion gain of each of the discharge tubes Xe1 and Xe2 can be changed. If possible, it is also possible to configure the device so that a constant amount of light can be obtained as described above without the reflective block 104.

FIG. 4 shows a second embodiment of the present invention in which there are four discharge tubes. 201a to 201d are discharge tubes, and the four discharge tubes are arranged in a square shape around the optical axis of a camera lens (not shown).
The trigger electrode of each discharge tube is connected to the output terminal of the trigger coil via an on/off switch. The other parts are the same as those in FIG. 2 of the first embodiment, so the circuit diagram is omitted. Reference numerals 204a to 204d are light guide tubes such as optical fibers that guide the light emitted from the discharge tubes 201a to 201d to the light receiving element 11, and each has a light entrance 202a at its tip.
~202d are provided, respectively. The light entrance ports 202a to 202d have the same structure, and FIG. 5 shows the details of the light entrance port 202a. Light entrance 202
a functions similarly to the reflection block 104 of the first embodiment of FIG. Furthermore, there are a holder 103 and reflecting mirrors 203a to 203d. Adjustment of the light quantity balance when there are four discharge tubes is also the same as in the first embodiment. That is, the light entrance 20 shown in FIG.
The conversion gain of the light incident from 2a to the output current of the light receiving element 11 is adjusted by an adjustment means to be described later.
Light intensity is balanced. _204a1 is a light shielding coating that covers the surface of the light guide tube 204a;
Light from sources other than the discharge tube 201a is prevented from entering in the middle of the light guide tube. A light shielding coating 204a ₁ is provided at the tip of the light guide tube 204a.
Instead, a portion of the side of the discharge tube 201a is cut out so that light from the discharge tube 201a can easily enter. The tip of the light guide tube 204a is fixed to an adjustment means 202a ₂ , and this adjustment means 202a ₂ is fixed near the flash tube 201a, and the adjustment means 20 made of a light shielding member
2a ₁ is attached to the adjustment means 201a ₂ .
The inner surface of the adjusting means 202a ₁ and the outer surface of the adjusting means 202a ₂ are threaded so as to be screwed together, and when the adjusting means 202a ₁ is rotated, it moves up and down to adjust the amount of light entering the light entrance 202a. , the adjustment means 202a ₁ and 202a ₂ are the light guide tube 204a.
It functions as an aperture that adjusts the amount of light that enters from the tip of the lens. Light entrance 202a, light guide tube 20
4a, depending on the configuration of the light receiving element 11, the discharge tube 201a
The light emission intensity of the light receiving element 11 is converted into an output current of the light receiving element 11. Adjustment means 20 provided at the light entrance 202a
Since the conversion gain is variable by 2a ₁ and 202a ₂ , adjustment can be performed using the same procedure as in the first embodiment. In other words, each discharge tube 2
The adjusting means 202a ₁ to 202d ₁ and 202a ₂ to 202d ₂ may be adjusted so that the amount of light to be controlled becomes a constant value when the lights 01a to 201d are individually controlled to emit light. In this case, adjustment of the reference power supply Vref is unnecessary. The flash device of the present invention adjusted in this way is controlled so that the amount of light is always constant regardless of the combination of one to four arc tubes.

FIGS. 6, 7, and 8 show a third embodiment of the present invention in which the output current of a light receiving element is electrically adjusted in gain. In Figure 6, Xe1 and Xe2 are flash discharge tubes,
11a and 11b are light receiving elements. FIG. 7 is an electric circuit diagram thereof, and the structure of the dimming circuit is different from that of the above-mentioned embodiment. Light receiving elements 11a, 11
b is the light receiving element shown in FIG. 6, which is connected to the current gain control circuits 14a and 14b, respectively. The current gain control circuits 14a and 14b control the respective discharge tubes.
Photodetector 11 for the emission intensity of Xe1 and Xe2
The integration capacitor 12 is charged by adjusting the balance between the output current values of a and 11b. comparator 13,
The functions of the integrating capacitor 12 and the reference power source Vref are the same as those of the dimming circuit of the previous embodiment, and the explanation thereof will be omitted. Current gain control circuit 14a, 1 as adjustment means
4b is the same, and its details are shown in FIG. The light receiving element 11a or 11b is connected to the input terminal IN of the current gain control circuit 14a or 14b, and the light receiving element 11a receives light from the discharge tube Xe1.
The output current I _IN is connected to the inverting input terminal of the operational amplifier A1, and a logarithmic compression diode D is connected from the output of the operational amplifier A1 to the inverting input terminal in a negative feedback loop in such a direction that the anode is on the output side of the operational amplifier A1. is connected. operational amplifier A1
The non-inverting input terminal of is connected to a reference power supply V1 whose voltage changes in proportion to the absolute temperature T. The output of operational amplifier A1 is connected to the base of transistor Q1, and the emitter of Q1 is connected to the output terminal of operational amplifier A2. The non-inverting input terminal of the operational amplifier A2 is connected to a regulating power supply V2 whose voltage changes in proportion to the absolute temperature T, and its inverting input constitutes a well-known voltage follower circuit short-circuited to the output of A2. The collector of transistor Q1 is connected to the input of a well-known current mirror circuit composed of PNP transistors Q2 and Q3.

When the light receiving current I _IN is injected into the input terminal IN, the output voltage V3 of the operational amplifier A1 is expressed by the following equation.

V3=V1+KT/qlnI _IN /I _S1 ...(1) (q: electron charge, T: absolute temperature, K: Boltzmann constant, I _S1 : reverse saturation current of diode D) Transistors Q2 and Q3 are the same I _c If the internal components have the same characteristics, the input current I _c and the output current I _put of the current mirror circuit will be equal.

I _c = I _put ...(2) Assuming that the current amplification factor of transistor Q1 is sufficiently large, emitter current I _E ≒ I _C (collector current)
Approximately, the base potential V3 of the transistor Q1 is expressed by the following equation.

V3=V2+KT/qlnIc/I _S2 ...(3) (I _s2 : Reverse saturation current between base and emitter of transistor Q1) If diode D and transistor Q1 are configured inside the same _IC , I _S1 and I _S2 are equal. Considering this, (1),
From equations (2) and (3), I _put = I _IN exp {q/KT (V1-V2)} ...(4) In other words, the output currents of the current gain control circuits 14a and 14b are expressed as shown in equation (4). It can be done. Here, as mentioned above, V1 and V2 are proportional to the absolute temperature, so V1−
V2 is proportional to absolute temperature and cancels out by 14
There is no temperature fluctuation in the output currents of a and 14b. Also,
The current gain can be changed freely by adjusting the voltage of V2. Therefore, the first
The adjustment of V2 can be similar to the adjustment of reflection block 104 in the embodiment. In other words, V2 of each current gain control circuit may be set so that the discharge tubes are caused to emit light one by one and the light is adjusted to a predetermined amount of light. Even when two lights are emitted at the same time, the light intensity is adjusted to be the same as when one light is used. In the embodiment of the present invention, all the discharge tubes are connected in parallel, but as disclosed in Japanese Patent Application Laid-Open No. 55-36885, a plurality of discharge tubes are arranged in series to make each discharge tube emit light. It is easily inferred that the selection of whether or not to enable the light is made by short-circuiting the anode and cathode of the discharge tube, and that it is possible to control the amount of light at a constant level using a similar dimming means.

(Effects of the invention) As described above, according to the invention, a constant amount of light can always be obtained even when an arbitrary number of discharge tubes are made to emit light. In particular, when taking extremely close-up shots, it is necessary to lower the guide number of the flash device due to the minimum aperture value of the photographic lens. According to the present invention, even in such cases, it is possible to selectively emit light from multiple discharge tubes and obtain a constant amount of light even if the illumination angle is freely changed. Exposure can be determined by calculation using In addition, since the conventional dimming method is used as a means of lowering the guide number without the need for attaching a dimming adapter or the like, it has the advantage of not wasting energy and shortening the recharging time. Furthermore, it is easy to make it possible to select several fixed amounts of light to be controlled, which further expands the possible photographing situations.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a flash device for close-up photography according to the first embodiment of the present invention, Fig. 2 is an electric circuit diagram of the embodiment shown in Fig. 1, and Fig. 3 is a line A-A in Fig. 1. 4 is a schematic configuration diagram of a flash device for close-up photography according to the second embodiment of the present invention, FIG. 5 is a partially enlarged view of the adjustment means in FIG. 4, and FIG. Schematic configuration diagram of a flash device for close-up photography according to a third embodiment of the invention, No. 7
The figure is an electrical circuit diagram of the embodiment shown in Fig. 6, and Fig. 8 is the electrical circuit diagram of the embodiment shown in Fig. 7.
FIG. 2 is a detailed circuit diagram of a part of the circuit shown in the figure. Explanation of symbols of main parts, 4...Main capacitor,
6...Trigger coil, 11, 11a, 11b...
...Photodetector, 12... Integrating capacitor, 13...
Comparator, 14a, 14b...Current gain control circuit, SW2, SW3...Selection switch, Vref...
...Reference power supply, Xe1, Xe2, 201a to 201d
...Flash discharge tube, 204a-204d...Light guide tube.

Claims (1)

[Claims for Utility Model Registration] An electronic flash device having a plurality of flash discharge tubes and a selection means for causing the plurality of flash discharge tubes to emit light simultaneously or selectively, which converts incident light into an electrical signal. a photoelectric conversion means for outputting, and a guide for guiding a portion of the flash light emitted from the plurality of flash discharge tubes to the photoelectric conversion means, which is determined at approximately the same ratio to each light flux irradiated toward the subject. an optical means; an integrating means for converting the light flux guided by the light guiding means into an electrical signal by the photoelectric converting means and integrating the electrical signal; An electric flash device comprising: a control means for stopping light emission of the flash discharge tube when a set level is reached.