JP4068929B2 - Strobe device and camera using the strobe device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the field of strobe devices and cameras, and more particularly to a technique using an organic EL panel.
[0002]
[Prior art]
A strobe device is a light-emitting device that is built in or externally attached to a camera, and instantly irradiates a subject with powerful light when the amount of light is insufficient or 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 volts supplied from a direct-current voltage source such as a battery to about 300 V, and supplies it 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 receives a high voltage supplied from the high-voltage power source 115 by the trigger transformer 121. The pressure is increased to about several kV and applied to the xenon tube 117.
[0005]
In the xenon tube 117, the internal xenon gas is excited by this high voltage of several kV, and powerful light is emitted when it returns to the ground state.
[0006]
As described above, the strobe device 101 of the prior art requires the trigger transformer 121 and the DC-DC converter transformer to excite the gas at a high voltage, which is an obstacle to downsizing the strobe device.
[0007]
[Problems to be solved by the invention]
The present invention has been created to solve the above-mentioned disadvantages of the prior art, and an object thereof is to provide a strobe device that does not require a high voltage.
[0008]
[Means for Solving the Problems]
The inventors of the present invention conducted an experiment using an organic EL panel of a type in which a polymer is applied to form a resin film, and the organic EL panel does not break even when a large current is applied for a short time. It was found that powerful luminescence can be obtained instantaneously. In general, an organic EL panel operates at several volts, but if a voltage higher than that (a few + V or less) is instantaneously applied, a large current can be instantaneously passed. Therefore, it is possible to obtain strong light emission at a lower voltage than a xenon lamp without using a step-up transformer.
[0009]
The present invention has been created based on the above knowledge, and the invention according to claim 1 is directed to a DC voltage source that outputs a DC voltage , an organic EL panel having a light emitting layer that emits light when a DC voltage is applied, A strobe device having an output switch for applying a DC voltage output from the DC voltage source to the organic EL panel when conducting, and a trigger circuit for causing the output switch to conduct for a predetermined time , wherein the light emitting layer is a resin made of a polymer. The output switch includes a transistor, and the transistor conducts for a light emission time of 1 μs or more and 100 μs or less, and the light emission layer emits a current that is 1 to 5 times the breakdown current for 1 second. It is a strobe device configured to be energized only for a period of time .
According to a second aspect of the present invention, there is provided a camera having the strobe device according to the first aspect, wherein the camera includes a battery and the battery is used as the DC voltage source.
[0010]
The present invention is configured as described above, and a voltage larger than the rated voltage is applied to the EL panel, and the output switch is made to conduct for a short time of about 1 μsec to 100 μsec. A large current that can be destroyed is instantaneously supplied to the EL panel, and the EL panel is configured to emit light for a period of time during which the output switch is turned on with a large amount of light.
[0011]
Since the voltage applied to the EL panel may be a low voltage of about several tens of volts or less, a transformer for generating a high voltage is not required unlike a xenon lamp.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Reference numeral 1 in FIG. 1 represents a strobe device as an example of the present invention.
The strobe device 1 includes 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 this 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 interruption by a signal output from the trigger circuit 18. When the output switch 22 is turned on by the trigger circuit 18, a positive voltage is applied to the transparent conductive film 52 and a metal electrode 56 is applied to the output switch 22. 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, pass through the layers 53 and 54, and reach the light emitting layer 54, where the electrons and holes recombine, 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 can be continuously lit for several thousand to several tens of thousands of hours when a rated voltage of about several volts is applied, but is several times the rated current that flows when the rated voltage is applied. For example, it is known that if a current of 5 times is passed, it is destroyed by energization for about 1 second.
[0018]
Since the magnitude of the rated current varies depending on the area of the organic EL panel 5, if the current that the organic EL panel 5 breaks down by energizing for 1 second is assumed to be a 1-second breaking current, When an electric current of 1 to 5 times is applied for a short time of 1 to 100 μs, a light emission amount several to several tens of times when the rated current is instantaneously passed can be obtained, and an organic EL panel 5 is not destroyed.
[0019]
In order to flow a current that is 1 to 5 times the breakdown current for 1 second, the output voltage of the DC voltage source 8 may be set to about several tens V (10 V to 20 V), and the energization time is 1 μsec. In order to set the time to 100 μsec or less, the energization time may be determined using an electronic circuit.
[0020]
For example, the trigger circuit 18 in 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 fixed time (here, 1 μsec or more and 100 μsec or less) determined by the time constant of the internal circuit.
[0024]
Here, the output switch 22 is a transistor such as a MOSFET or IGBT, and the signal output from the second monostable multivibrator 13 is input to the gate terminal or base terminal of the output switch 22 and is conducted only 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 applied. Flows and emits intense light instantaneously.
[0026]
Reference numerals 31 and 32 in FIG. 1 are pull-down resistors. When the trigger switch 11 is not closed by the pull-down resistors 31 and 32, the input terminal and the output switch 22 of the first monostable multivibrator 13 are provided. The gate terminal or base terminal of the first monostable multivibrator 13 and the output switch 22 are configured not to 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. The photometric sensor 45 receives light emitted from the subject 40. The received light amount is output to the controller 44.
[0028]
The controller 44 determines the necessity / unnecessity of light emission from the amount of light when the shutter button 47 is pressed. 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. Due to the operation of the strobe device 1, the shortage of light quantity is resolved, and even the backlight is well imaged in detail.
[0030]
In this camera 2, the DC voltage source 8 of the strobe device 1 is shared with a power source that operates 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 strobe device 1 of the present invention can also be used for a silver salt camera that fixes an image of the subject 40 on a silver salt film.
[0032]
Moreover, when requesting development and printing from a specialty store, it can be used for a film with a lens for handing the condenser lens 42 and the strobe device 1 together with the silver salt film.
[0033]
【The invention's effect】
Compared to a xenon lamp that requires a high voltage of several kV, a large amount of light can be obtained at a low voltage, thus eliminating the need for a transformer. In addition, 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 a structure of an EL panel. FIG. 3 is a circuit block diagram of a camera of the present invention. [Explanation of symbols]
DESCRIPTION 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 having a light emitting layer that emits light upon application of a DC voltage;
An output switch that applies a DC voltage output from the DC voltage source to the organic EL panel when conducting,
A strobe device having a trigger circuit for conducting the output switch for a predetermined time ,
The light emitting layer is composed of a resin film made of a polymer,
The output switch has a transistor,
The stroboscopic device is configured such that the transistor conducts for a light emission time of 1 μs or more and 100 μs or less, and a current that is 1 to 5 times the breakdown current for 1 second is supplied to the light emitting layer for the light emission 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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