JPH11237667A - Stroboscopic booster device and camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a service life from being shortened due to the deterioration of a flash light emitting tube and to prevent a strobe light emitting part from getting larger and cost from rising by providing an auxiliary capacitor connected to the main capacitor of a stroboscopic device incorporated in a camera in parallel and a current limiter circuit connected to the auxiliary capacitor in series. SOLUTION: Relating to a camera main body 1, the main capacitor 13 is connected to the flash light emitting tube 14 in parallel. Connectors 19 and 20 are provided at both ends of the capacitor 13. Meanwhile, in a booster circuit 2, the current limiter circuit 21 and the auxiliary capacitor 22 are connected in series between the connectors 19 and 20. Then, the capacitors 22 and 13 are connected in parallel. The circuit 21 limits a discharge current discharged from the capacitor 22. At the time of emitting light, the capacitor 22 also discharges with the discharge of the capacitor 13 but the current flowing from the capacitor 22 to the tube 14 is limited by the circuit 21, so that a peak value is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash light emitting device for a camera, and more particularly, to a strobe booster device and a camera system mounted for increasing the light amount of the flash light emitting device.

[0002]

2. Description of the Related Art In recent years, various cameras incorporating a strobe device have been used. In such a camera with a built-in strobe, since a small strobe device is built in the camera body, when increasing the amount of light of the strobe, the size of an arc tube and a capacitor for charging is limited.

[0003] Therefore, for example, Japanese Patent Application Laid-Open No. 5-28914.
No. 9 discloses a technique for attaching a detachable auxiliary capacitor that can be connected in parallel with a built-in main condenser and increases the amount of light of a strobe built in the camera.

[0004]

However, according to the technique disclosed in Japanese Patent Laid-Open No. Hei 5-289149, it is possible to increase the amount of light of the strobe, but a large current flows through the flash tube of the built-in strobe. For this reason, there is a problem that the flash arc tube is greatly deteriorated and the life is shortened.

[0005] As a method of improving the life of the flash arc tube, the arc length or the tube diameter of the flash arc tube is increased, or the glass or discharge electrode used is changed to one having higher durability. It is conceivable that the capacitor can be sufficiently held even when connected.

However, when the arc tube is changed in this way, the size of the light emitting portion of the strobe becomes large, and the cost becomes high. As a result, the size and cost of the camera itself increase.

[0007] In addition, when the auxiliary capacitor is not connected, the above-mentioned flash arc tube has an over specification. The present invention has been made in view of the above problems, and an object of the present invention is to prevent a flash luminous tube from being severely deteriorated and shortening its life, preventing an increase in the size and cost of a strobe light emitting unit, An object of the present invention is to provide a strobe booster device and a camera system that do not cause over-spec.

[0008]

That is, the present invention is a strobe booster device mounted on a camera with a built-in strobe to increase the amount of flash light, and is connected in parallel with a main capacitor of the strobe device built in the camera. An auxiliary capacitor and a current limiting circuit connected in series with the auxiliary capacitor are provided.

Further, the present invention provides a camera with a built-in strobe,
In a camera system comprising a strobe booster device mounted on the camera to increase a strobe light emission amount,
The strobe booster device includes an auxiliary capacitor connected in parallel with a main capacitor of the strobe device built in the camera, and a current limiting circuit connected in series with the auxiliary capacitor.

The present invention relates to a strobe booster device mounted on a camera with a built-in strobe to increase the amount of flash light, wherein an auxiliary capacitor is connected in parallel with a main capacitor of the strobe device built in the camera. Then, a current limiting circuit is connected in series with the auxiliary capacitor.

Further, the camera system according to the present invention comprises a camera with a built-in strobe and a strobe booster device mounted on the camera to increase the amount of strobe light emission. In the strobe booster device, an auxiliary capacitor is connected in parallel with the main capacitor of the strobe device built in the camera, and a current limiting circuit is connected in series with the auxiliary capacitor.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the concept of the present invention, and is a block diagram showing a configuration of a camera system according to the first embodiment.

In FIG. 1, the camera system comprises a camera body 1 having a built-in strobe, and a booster circuit 2 which is detachably attached to the camera body 1 and increases the amount of light of the built-in strobe of the camera body 1. Be composed.

The camera body 1 includes a battery power source 11, a main capacitor 13, a boosting charging circuit 12 for boosting the voltage of the battery power source 11 and charging the main capacitor 13 with the charge, and connected in parallel with the main capacitor 13. A flash emission tube 14 and a series circuit of a light emission control circuit 15 for varying the light emission amount according to the subject distance and the aperture, and a control unit for controlling the boosting charging circuit 12, the light emission control circuit 15, and a camera circuit (not shown). 16. Note that connectors 19 and 20 are provided at both ends of the main capacitor 13 for making electrical connection when the detachable booster circuit 2 is mounted.

On the other hand, the booster circuit 2 is connected to the connector 1
Between 9 and 20, a current limiting circuit 21 and an auxiliary capacitor 22 are connected in series. The current limiting circuit 21
This is for limiting the discharge current discharged from the auxiliary capacitor 22.

FIG. 2 is a circuit diagram showing a configuration of the current limiting circuit 21 including the auxiliary capacitor 22. In FIG. 2, a current limiting circuit 21 includes a current limiting coil 25,
This is for discharging the energy stored in the coil 25, and is constituted by a parallel circuit of a diode 26 for absorbing the vibration of the current from the auxiliary capacitor 22.

Next, the operation of the first embodiment will be described with reference to FIG. FIG. 3 is a characteristic diagram showing a change with time of the discharge current of the main capacitor 13. As shown in FIG. In FIG. 3, the vertical axis represents the current value flowing through the flash arc tube 14 during light emission, and the horizontal axis represents time.

FIG. 3A shows a characteristic curve when the auxiliary capacitor 22 is connected in parallel with the flash tube 14 without using the current limiting circuit 21, and FIG. 3 shows a characteristic curve when connected between the flash tubes 14.

As can be seen from FIG. 3, the current of the characteristic curve a rises sharply from the start of light emission, and the maximum value of the current is larger than the characteristic curve b. On the other hand, the current of the characteristic curve b initially rises steeply by the discharge of the main capacitor 13 built in the camera body 1, but the current decreases after the accumulated charge of the built-in main capacitor 13 is released. (Illustrated section t). Then, when the section t elapses,
The auxiliary capacitor 22 is also discharged so as to overlap with the discharge of the main capacitor 13.

However, the current flowing from the auxiliary capacitor 22 to the flash tube 14 is limited by the current limiting coil 25. Therefore, the curve of the current value becomes gentle, and the absolute value of the current value becomes smaller than that of the characteristic curve a.

The resistance of the flash arc tube 14 is as follows.
It has been found that it is greatly related to the peak value of the current flowing through. The reason for this is that the damage to the discharge electrode and the glass tube increases as the peak value of the current increases. That is, if the flash arc tube 14
Even if the energy input to the power supply is the same, there is a large difference in the life depending on the absolute value of the current value.

That is, when light is emitted in accordance with the characteristic curve b, the absolute value of the current is smaller than in light emission in accordance with the characteristic curve a in which the absolute value of the current is large, and the flash arc tube 14 is less damaged. Therefore, even if the auxiliary condenser 22 for increasing the light amount is connected to the flash tube 14 built in the camera body 1, the life of the flash tube 14 is not shortened.

Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram showing a configuration of a booster circuit of a camera system according to a second embodiment of the present invention.
In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

In FIG. 4, an auxiliary capacitor 22 and an IGBT (bipolar MOSFET) 37 for switching a current discharged from the auxiliary capacitor 22 are connected between the connectors 19 and 20. A series circuit of a resistor 31 and a Zener diode 32 is connected to the auxiliary capacitor 22 in parallel. In parallel with the Zener diode 32, a backup capacitor 33, a monomultivibrator (MMV) 35 to which a photodiode 34 as a light receiving element is connected, and a pulse generator (PG) 36 are connected. Furthermore,
A diode 38 is connected between the emitter and the collector of the IGBT 37.

The pulse generator 36 is an IGBT
This is for outputting a pulse train for turning on and off the 37. The mono multivibrator 35 is
This is for receiving the rising of the light emission of the built-in strobe and outputting a one-shot pulse for starting the pulse generator 36 to the pulse generator 36.

Further, the backup capacitor 33 is for holding the circuit power supply voltage of the monomultivibrator 35, and this power supply voltage is set by the Zener diode 32 from the auxiliary capacitor 22 via the resistor 31. It is obtained by applying a voltage.

In such a configuration, when the flash tube 14 in the camera body 1 emits light, the photodiode 34
Receives this, and the trigger of the mono-multi vibrator 35 is output. The pulse train described above is output from the pulse generator 36 based on the trigger from the mono-multi vibrator 35. Thereby, the IGBT 37 is controlled, and the current discharged from the auxiliary capacitor 22 is switched.

In the first embodiment described above, the current is limited by the coil. In the second embodiment, however, the beak current of the discharge is suppressed by switching the discharge current by the IGBT 37. . Therefore, the limit value of the photoelectric current can be freely set only by changing the duty of the output pulse train of the pulse generator 36.

According to the above embodiment of the present invention, the following configuration can be obtained. (1) A strobe built-in camera including a flash tube, a main capacitor for supplying electric charge to the flash tube, and a connection terminal for electrically connecting to an electrode of the main capacitor; A strobe booster including an auxiliary capacitor connectable in parallel with the main capacitor, and a current limiting circuit connected in series with the auxiliary capacitor and limiting a peak value current of a discharge current of the auxiliary capacitor. Camera system.

(2) The camera system according to (1), wherein the current limiting circuit is a coil. (3) The camera system according to (1), wherein the current limiting circuit includes at least a switching element and a pulse generator.

[0031]

As described above, according to the present invention,
Even if an auxiliary capacitor is connected to increase the amount of light from the built-in flash in the camera body, the flash tube will not be severely degraded and its life will not be shortened, preventing the flash unit from becoming larger and costly. Thus, it is possible to prevent over-spec.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a concept of the present invention and showing a configuration of a camera system according to a first embodiment.

FIG. 2 is a circuit diagram showing a configuration of a current limiting circuit 21 including an auxiliary capacitor 22.

FIG. 3 is a characteristic diagram showing a change over time of a discharge current of a main capacitor 13;

FIG. 4 is a diagram showing a configuration of a booster circuit of a camera system according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 camera body, 2 booster circuit, 11 battery power supply, 12 boost charging circuit, 13 main capacitor, 14 flash tube, 15 light emission control circuit, 16 control section, 19, 20 connector, 21 current limiting circuit, 22 auxiliary capacitor, 25 Coil, 26, 38 diode, 31 resistor, 32 Zener diode, 33 backup capacitor, 34 photodiode, 35 mono multivibrator (MMV), 36 pulse generator (PG), 37 IGBT (bipolar MOSFET).

Claims (3)

[Claims] 1. A strobe booster device mounted on a camera with a built-in strobe to increase the amount of strobe light, comprising: an auxiliary capacitor connected in parallel with a main capacitor of the strobe device built in the camera; A current limiting circuit connected to the strobe booster device. 2. The strobe booster device according to claim 1, wherein said current limiting circuit is a switching means including a coil or a switching element and a pulse generating circuit. 3. A camera system comprising a camera with a built-in strobe and a strobe booster device mounted on the camera to increase the amount of strobe light emission, wherein the strobe booster device includes a main condenser of the strobe device built in the camera. A camera system comprising: an auxiliary capacitor connected in parallel; and a current limiting circuit connected in series with the auxiliary capacitor.