JPH0544011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a flash light emitting device used as a lighting device for photography.

``Prior Art'' A flash light emitting device used for photography is widely known, and FIG. 2 shows its basic circuit configuration.

In this circuit diagram, 13 is a DC-DC converter, which is activated by closing the power switch 12.
The DC-DC converter 13 starts oscillating, boosts the DC voltage of the battery power supply 11, and boosts the DC voltage of the main discharge capacitor 1.
4 to the specified voltage.

15 is a flash discharge tube, which is connected in parallel to the main discharge capacitor 14 and converts the energy stored in the main discharge capacitor 14 into light energy. 16 is an excitation electrode, 21 is a trigger resistor, 22
23 is a trigger capacitor, 23 is a trigger switch, and 24 is a trigger transformer, which form a trigger circuit for the flash discharge tube 15.

In this trigger circuit, when the trigger switch 23 is closed in response to the shutter opening, the charge in the trigger capacitor 22 is discharged to the primary coil of the trigger transformer 24. The high voltage generated is applied to the excitation electrode 16.

As a result, the charge in the main discharge capacitor 14 is discharged to the flash discharge tube 15, which has become a low impedance, and the flash discharge tube 15 starts emitting light. This flash discharge tube 15 stops emitting light when the charging voltage of the main discharge capacitor 14 drops to a predetermined voltage.

"Problems to be Solved by the Invention" The trigger circuit of the flash light emitting device described above closes the trigger switch 23, discharges the charge in the trigger capacitor 22 all at once to the primary coil of the trigger transformer 24, and It is configured to generate high voltage in the side coil.

In such a configuration, a parasitic oscillating current is generated by the inductance of the primary coil of the trigger transformer 24 and the capacitance of the trigger capacitor 22, which generates a high oscillating voltage in the secondary coil. radiated as noise.

Furthermore, since the load on the secondary side of the trigger transformer 24 is connected to the excitation electrode 16 of the high-impedance flash discharge tube 15, the above-mentioned oscillating voltage generated on the secondary side of the trigger transformer 24 becomes an even higher voltage. Become something.

Furthermore, noise is generated from the trigger transformer 24 due to leakage magnetic flux of the trigger transformer 24. As mentioned above, the trigger circuit of the conventional flash light emitting device has many sources of noise.
Because of their high levels, these noises cause the camera's electronic drive circuit to malfunction.

In recent years, cameras with built-in microcomputers have been widely used, and there is an urgent need to reduce the generation of the above-mentioned noise.

"Means for Solving the Problems" The present invention has been developed in view of the above-mentioned problems, and is based on a flash discharge tube that is triggered to discharge electrical energy pre-stored in a main discharge capacitor to emit flash light. The light emitting device includes a light emitting source that emits light in response to a trigger operation;
A photovoltaic body that generates a high voltage upon receiving light from the light emitting source is provided, and a trigger means is provided for applying the high voltage generated in the photovoltaic body as an excitation voltage to the flash discharge tube. We propose a flash light emitting device.

"Operation" The main discharge capacitor is charged to a specified voltage,
When you move on to the trigger operation when the flash is ready,
The light emitting source emits light, and the light is irradiated onto the photovoltaic body, thereby generating a high voltage in the photovoltaic body.
The high voltage generated in this photovoltaic body is applied as an excitation voltage to the flash discharge tube, and the flash discharge tube becomes a low impedance, discharging the charge accumulated in the main discharge capacitor and emitting flash light.

``Example'' Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a flash light emitting device according to the present invention, in which a trigger means comprising light emitting sources 19a, 19b and a photovoltaic body 20 is provided in place of the trigger circuit of a conventional flash light emitting device.

Note that circuit members that are the same as those in FIG. 2 will be described with the same reference numerals.

The photovoltaic body 20 has one terminal connected to the excitation electrode 16 of the flash discharge tube 15 and the other terminal connected to the cathode side of the flash discharge tube 15.

In addition, this photovoltaic body 20 is a series connection body of many photovoltaic elements, and when it receives light, it can generate up to 2KV.
Generates 3KV voltage. For example, a configuration is used in which 4,000 to 5,000 photovoltaic elements that generate a voltage of about 0.5V are connected in series.

It should be noted that the photovoltaic body 20 can be of a monolithic type and can be manufactured into a compact product.

This type of photovoltaic generator 20 is disclosed in Japanese Patent Publication No. 62-27755 and is widely known.

That is, as disclosed in this publication as an example, transparent conductive films are separately formed on a transparent substrate such as glass, and an amorphous silicon layer is provided on each transparent conductive film.

This amorphous silicon layer is sequentially P-type layer from the bottom,
It is a non-doped layer and an n-type layer, with a part of the transparent conductive film remaining on one side and extending to the outside of the transparent conductive film on the other side.

After this amorphous silicon layer is formed by glow discharge decomposition of monosilane gas, a resist material is applied in a predetermined pattern, and the portions of the semiconductor layer without resist are removed by plasma etching or the like.

A metal electrode is then applied, for example by vapor deposition, using a metal mask.

In this way, a photovoltaic body 20 can be constructed in which a large number of photovoltaic elements are connected in series.

The light emitting sources 19a and 19b are the photovoltaic bodies 2
These are preferably infrared light emitting diodes that have excellent luminous efficiency and response speed.

The light emitting sources 19a and 19b are triggered by the trigger switch 18.
The configuration is such that power is supplied from the battery power source 11 via the current limiting resistor 17, but these light emitting sources 19a,
19b are not necessarily connected in parallel as shown in the figure, and their number can be increased or decreased as desired.

In the flash light emitting circuit of this embodiment, when the trigger switch 18 is closed with the main discharge capacitor 14 charged and ready to emit light, the light emitting sources 19a and 19b are activated in response to the closing of the switch 18.
is supplied with power by the battery power source 11 and emits light. As a result, the photovoltaic body 20 emitted by the light emitting sources 19a and 19b generates a high voltage, and the flash discharge tube 15, which receives this high voltage at the excitation electrode 16, becomes a low impedance, and the main discharge capacitor 14 is charged. Discharges the charge and emits flash light.

Although one embodiment of the present invention has been described above,
The trigger circuit according to the present invention is not limited to a flash light emitting device for photography, but can be implemented as a trigger circuit for a discharge tube having a trigger electrode, such as a flash light emitting device used as a signal source for remote control.

"Effects of the Invention" As described above, in the flash light emitting device according to the present invention, the trigger means for causing the flash discharge tube to emit light is constituted by a light source and a photovoltaic body, and the flash light emitting device according to the present invention is free from noise caused by the trigger operation unlike the conventional trigger circuit. occurrence is very low. Therefore, even if it is incorporated as a flash light emitting device built into a camera, there is no risk of the electronic circuit for controlling the camera malfunctioning.

Further, since there is no risk of applying a high trigger voltage to the trigger switch section, there is an advantage that there is no need to use wiring for the trigger switch section using an insulating member with a high withstand voltage.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a flash light emitting device showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a flash light emitting device shown as a conventional example. 13... DC-DC converter, 14... Main discharge capacitor, 15... Flash discharge tube, 16... Excitation electrode, 18... Trigger switch, 19a, 19
b... Light emitting source, 20... Photovoltaic body.

Claims (1)

[Claims] 1. In a flash light emitting device that emits flash light by discharging electric energy stored in advance in a main discharge capacitor when a flash discharge tube is triggered,
A light emitting source that emits light in response to a trigger operation and a photovoltaic body that generates a high voltage upon receiving light from the light emitting source are provided, and the high voltage generated in the photovoltaic body is used as the excitation voltage of the flash discharge tube. A flash light emitting device characterized in that it is provided with a trigger means for applying voltage.