JP2004109430A - Stroboscopic device and camera using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stroboscope by which strong emitted light is obtained at low voltage. <P>SOLUTION: A high current to such an extent that it ordinarily ruptures an organic EL panel 5 for one second or less is instantaneously made to flow to the panel 5, so that light is strongly emitted only for a very short time and irradiates a subject. Since the high current is made to flow just by directly applying voltage outputted from a DC voltage source 8 such as a battery to the panel 5, a step-up transformer required when using a xenon lamp requiring several kV is dispensed with. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a field of a strobe device and a camera, and particularly relates to a technique using an organic EL panel.
[0002]
[Prior art]
The strobe device is a built-in or external light-emitting device of the camera, and irradiates the subject with powerful light instantaneously when the amount of light is insufficient or the subject is backlit, thereby improving the image quality. Reference numeral 101 in FIG. 4 denotes a general strobe device, which includes a high-voltage power supply circuit 115, a control circuit 116, a xenon tube 117, and a gate circuit 118.
[0003]
The high-voltage power supply 115 includes a DC-DC converter, boosts a voltage of about several V supplied from a DC voltage source such as a battery to about 300 V, and supplies the voltage to the control circuit 116.
[0004]
The control circuit 116 includes a trigger transformer 121 and an output transistor 122. When the output transistor 122 is turned on by the gate circuit 118, the control circuit 116 further increases the high voltage supplied from the high-voltage power supply 115 by the trigger transformer 121. The pressure is raised to about several kV and applied to the xenon tube 117.
[0005]
The xenon gas in the xenon tube 117 is excited by the high voltage of several kV, and strong light is emitted when it returns to the ground state.
[0006]
As described above, the conventional strobe device 101 requires the trigger transformer 121 and the DC-DC converter transformer in order to excite the gas at a high voltage, which is an obstacle to miniaturization of the strobe device.
[0007]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages of the related art, and has as its object to provide a strobe device which does not require a high voltage.
[0008]
[Means for Solving the Problems]
The inventors of the present invention have conducted experiments using an organic EL panel of a type in which a polymer film is formed by applying a polymer. As a result, the organic EL panel does not break down even when a large current flows for a short time. We found that strong light emission can be obtained instantaneously. Generally, an organic EL panel operates at several volts, but if a higher voltage (about several volts or less) is applied instantaneously, a large current can flow instantaneously. Therefore, even without using a step-up transformer, it is possible to obtain strong light emission at a lower voltage than a xenon lamp.
[0009]
The present invention has been made based on the above findings, and the invention according to claim 1 is a DC voltage source that outputs a DC voltage, an organic EL panel that emits light by application of the DC voltage, and the DC voltage source that is electrically connected. A strobe device having an output switch for applying a DC voltage output from a voltage source to the organic EL panel, and a trigger circuit for conducting the output switch for a predetermined time.
According to a second aspect of the present invention, there is provided a camera having the strobe device according to the first aspect, further comprising a battery, wherein the battery is used as the DC voltage source.
[0010]
The present invention is configured as described above, and applies a voltage higher than the rated voltage to the EL panel to make the output switch conductive for a short time of about 1 μsec to 100 μsec. A large current enough to destroy the LED panel is instantaneously supplied to the EL panel, and the EL panel emits light with a large amount of light during the time when the output switch is turned on.
[0011]
Since the voltage applied to the EL panel can be as low as several tens of volts or less, a transformer for generating a high voltage unlike a xenon lamp is not required.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Reference numeral 1 in FIG. 1 indicates a strobe device according to an example of the present invention.
The strobe device 1 has a DC voltage source 8, an organic EL panel 5, an output switch 22, and a trigger circuit 18.
[0013]
As shown in FIG. 2, the organic EL panel 5 includes a transparent substrate 51 such as glass, a transparent conductive film 52, a hole transport layer 53, a light emitting layer 54, an electron transport layer 55, and a metal electrode 56. They are stacked in order.
[0014]
The hole transport layer 53, the light emitting layer 54, and the electron transport layer 55 are formed of a resin film obtained by applying and drying a raw material liquid.
[0015]
In the organic EL panel 5, the transparent conductive film 52 is connected to the positive voltage side output terminal 81 of the DC voltage source 8, and the metal electrode 56 is connected to the ground potential side output terminal 82 of the DC voltage source 8 via the output switch 22. It is connected.
[0016]
The output switch 22 is switched between conduction and cutoff by a signal output from the trigger circuit 18. When the output switch 22 is rendered conductive by the trigger circuit 18, a positive voltage is applied to the transparent conductive film 52 and a voltage is applied to the metal electrode 56. A ground voltage is applied. With this voltage, holes and electrons are injected into the hole transport layer 53 and the electron transport layer 55, respectively. When the electrons pass through the layers 53 and 54 and reach the light emitting layer 54, the electrons and holes are recombined there, and light is emitted. appear. The generated light is emitted to the outside through the transparent substrate 51.
[0017]
Here, the general organic EL panel 5 is capable of continuous lighting for thousands to tens of thousands of hours when a rated voltage of about several volts is applied, but several times the rated current flowing when the rated voltage is applied. It is known that, for example, when a current of 5 times is applied, the device is destroyed by energization for about 1 second.
[0018]
Since the magnitude of the rated current also varies depending on the area of the organic EL panel 5, if the current that the organic EL panel 5 breaks when energized for one second is the one-second breakdown current, the organic EL panel has a one-second breakdown current. When an electric current of 1 to 5 times is applied for a short time of 1 μs to 100 μs for a short time, a light emission amount several times to several tens times that when a rated current is instantaneously supplied can be obtained. 5 does not break.
[0019]
In order to allow a current of 1 to 5 times the one-second breakdown current to flow, the output voltage of the DC voltage source 8 may be set to about ten and several volts (10 to 20 V), and the energizing time may be 1 μsec. In order to reduce the current to 100 μs or less, the energization time may be determined using an electronic circuit.
[0020]
For example, the trigger circuit 18 of FIG. 1 includes a trigger switch 11 and first and second monostable multivibrators 12 and 13.
[0021]
The first monostable multivibrator 12 is connected to the positive voltage side output terminal 81 of the DC power supply 8 via the trigger switch 11, and the trigger switch 11 is turned on to remove chattering from the input voltage. The pulse is output to the second monostable multivibrator 13.
[0022]
When the signal output from the first monostable multivibrator 12 is input to the second monostable multivibrator 13,
[0023]
The second monostable multivibrator 13 outputs a signal to the output switch 22 for a predetermined time (here, a time of 1 μsec to 100 μsec) determined by a time constant of the internal circuit.
[0024]
Here, the output switch 22 is a transistor such as a MOSFET or an IGBT, and a signal output from the second monostable multivibrator 13 is input to its gate terminal or base terminal, and conducts for the input time.
[0025]
While the output switch 22 is conducting, the EL panel 5 is connected to the positive voltage side output terminal 81 and the ground potential side output terminal 82, and a current of 1 to 5 times the one-second breakdown current of the EL panel 5 is generated. It flows and emits light instantaneously.
[0026]
Reference numerals 31 and 32 in FIG. 1 denote pull-down resistors. When the trigger switch 11 is not closed by the pull-down resistors 31 and 32, the input terminal of the first monostable multivibrator 13 and the output switch 22 are turned off. Is grounded, and the first monostable multivibrator 13 and the output switch 22 do not operate.
[0027]
Reference numeral 2 in FIG. 3 indicates a camera incorporating the strobe device 1.
The camera 2 includes a lens 42, a CCD device 43, a controller 44, a storage device 46, a shutter button 47, and a photometric sensor 45, which receives light emitted from the subject 40. Then, it is configured to output the amount of received light to the controller 44.
[0028]
The controller 44 determines the necessity / non-necessity of light emission based on the light amount when the shutter button 47 is pressed, and turns on the trigger switch 11 when the light emission is to be performed. Irradiate with strong light.
[0029]
The light returned from the subject 40 is collected by the lens 42 and forms an image on the CCD device 43. The imaging result is transmitted to the controller 44 and stored in the storage device 46. By the operation of the strobe device 1, the shortage of light quantity is eliminated, and even in the case of backlight, an image is formed well in detail.
[0030]
In this camera 2, the DC voltage source 8 of the strobe device 1 is shared with a power supply for operating the controller 44 and the storage device 46, and a rechargeable battery can be used.
[0031]
Although the camera 2 is a digital camera, the flash device 1 of the present invention can also be used in a silver halide camera for fixing an image of the subject 40 on a silver halide film.
[0032]
Further, when requesting development and printing to a specialty store, the film can be used not only with the silver halide film but also with a lens-equipped film that also passes the condenser lens 42 and the strobe device 1.
[0033]
【The invention's effect】
Since a large amount of light can be obtained at a low voltage as compared with a xenon lamp requiring a high voltage of several kV, a transformer is not required. Further, a circuit for light emission can be simplified.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of an example of a strobe device of the present invention. FIG. 2 is a diagram showing the structure of an EL panel. FIG. 3 is a circuit block diagram of a camera of the present invention. FIG. [Explanation of symbols]
1 strobe device 2 camera 5 organic EL panel 8 DC voltage source 22 output switch

Claims (2)

A DC voltage source that outputs a DC voltage;
An organic EL panel that emits light when a DC voltage is applied;
An output switch for applying a DC voltage output from the DC voltage source to the organic EL panel when the organic EL panel is turned on;
A trigger circuit for turning on the output switch for a predetermined time. A camera having the strobe device according to claim 1, further comprising a battery, wherein the battery is used as the DC voltage source.

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