JPH0535560Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is intended for use in a flash discharge tube used as a light source for electronic flash devices used as an artificial light source during photography.

Prior Art In recent years, electric devices such as the above-mentioned electronic flash devices that use flash discharge tubes as light sources have been desired to be smaller, more portable, and brighter than in the past, and there has been a strong demand for miniaturization of flash discharge tubes. It is requested.

As shown in FIGS. 4a and 4b, such flash discharge tubes are extremely common. A rod-shaped glass tube 1 is filled with a prescribed gas, and rod-shaped electrodes 2, 3 or 3 are attached to both ends of the glass tube 1. Cap-shaped electrodes 5 and 6 were sealed together, and a transparent conductive trigger electrode 4 was applied to the surface of the glass tube 1 (Jikkosho).
59-1310, etc.).

Problems that the invention is intended to solve However, when considering miniaturization, the rod-like shape inevitably imposes limitations when considering the desired brightness and luminous efficiency.

On the other hand, when considering miniaturization as a light source, it is sufficient if it can be made into a point light source, and conventionally, for example, flash discharge tubes as shown in FIGS. 5a, b, and c have been proposed or put into practical use.

That is, the discharge tube shown in FIG. 5a has the electrodes 2 and 3 sealed to one side of the envelope 1 to create a point light source, and the discharge tube shown in FIG. 5b has the envelope 1 sealed to one side. The U-shaped discharge tube, and the discharge tube shown in c in the same figure, have an envelope 1.
It is formed into a spiral shape.

As mentioned above, various types of flash discharge tubes have been proposed or put into practical use.
Considering miniaturization, the discharge tube shown in Figure 5a has a discharge length of about 3 to 5 mm, and its shape can be extremely miniaturized, that is, it can be regarded as a point light source, but because the discharge length is short, Since the impedance becomes small and the luminous efficiency becomes extremely poor, there is a problem that it cannot be used as a light source.

Therefore, discharge tubes such as those shown in FIGS. 5b and 5c have been put into practical use, but like the rod-shaped discharge tube shown in FIG. There is a limit to this, and the machining accuracy is also poor.
The problem is that it is expensive and can only be used for special purposes.

Furthermore, when looking at the trigger electrode in the conventional discharge tube as described above, it is found that it is formed of a well-known transparent conductive film as shown in the drawings, or that the trigger wire is connected to the envelope 1, although not shown. It is generally formed by wrapping it around the outer circumferential surface of. However, in the former case, there is a potential problem that the transparent conductive coating may break and the luminescence becomes unstable, and in the latter case, the trigger voltage is not supplied to the envelope, which also applies to the former case. 1, the discharge path easily changes depending on the state inside the envelope at that time, and furthermore, thermal shock is applied to the envelope 1 when the trigger voltage is supplied. ,
This has the problem that the trigger wire tends to loosen or crack, and a sufficiently long life cannot be expected.

The present invention was created in consideration of the above-mentioned problems, and aims to provide a long-life flash discharge tube that has a small size that can be regarded as a point light source, has high luminous efficiency, and is capable of stable trigger operation. purpose.

Means for Solving the Problems The flash discharge tube according to the present invention includes a transparent cylindrical envelope made of glass, for example, with only one end open, two electrodes, an anode and a cathode, and a tube inside the envelope. ,
A conductive ceramic member that is divided into a plurality of spaces that are connected in series to form a discharge path and also serves as the trigger electrode itself; a base body that holds a conductive ceramic member and seals a predetermined gas in an upper envelope and then is sealed to the open end of the envelope; The trigger terminal is configured to be electrically connected to the member.

Function Since the flash discharge tube according to the present invention is constructed as described above, even if the absolute distance between the two electrodes is short as in the discharge tube shown in Fig. 5a, the flash discharge tube according to the present invention can be The discharge operation accompanying the supply of the trigger voltage is performed through a plurality of spaces connected in series by conductive ceramic members. That is, a discharge path is formed along the conductive ceramic member that is the trigger electrode.

Therefore, the discharge length is the sum of the above-mentioned multiple spaces, so by selecting the shape and designing the position of the conductive ceramic member, etc., it is possible to obtain the discharge length that can obtain the optimal luminous efficiency while achieving miniaturization. It will be done.

Furthermore, thermal shock is not directly applied to the envelope when the trigger voltage is supplied.

Embodiment FIGS. 1a and 1b are a longitudinal sectional view and a side view, respectively, showing an embodiment of a flash discharge tube according to the present invention.

In the drawings, the same reference numerals as those in FIG. 3 and the like indicate the same functional members. 1' is a translucent cylindrical envelope made of, for example, quartz glass or translucent alumina ceramic with an open end; 7 is a conductive ceramic that divides the inside of the envelope 1' into two spaces 9a and 9b. The parts are shown. In addition, the spaces 9a, 9
It is clear from the drawing that b are connected to each other above the conductive ceramic member 7.

Needless to say, the conductive ceramic member 7 is selected to have excellent heat resistance and less generation of impure glass, and its size should be selected as long as the gap between it and the inner circumferential surface of the envelope 1' is small. The smaller the better, that is, it is preferable that the space other than the connecting portion between the spaces 9a and 9b be in close contact with the inner circumferential surface of the envelope 1', and its maximum dimension is approximately equal to the inner circumferential diameter of the envelope 1'. It is done like this. Further, the conductive ceramic member 7 is selected to have a coefficient of thermal expansion close to that of the envelope 1'.

8 is a trigger terminal that is electrically connected to the conductive ceramic member 7; 10 is a trigger terminal that holds the conductive ceramic member 7, anode 2, cathode 3, and trigger terminal 8 in an airtight state; The substrate is shown sealed to one end.

The base body 10 can be made of glass, ceramic, or the like, and of course, the base body 10 is selected to have a thermal expansion coefficient close to that of the envelope 1'.

11 is an adhesive member that adheres the base 10, the envelope 1', the electrodes 2, 3, the conductive ceramic member 7, or the trigger terminal 8 while maintaining an airtight state;
For example, fritted glass is used.

Now, the flash discharge tube according to the present invention having the above-mentioned configuration is manufactured in the following manner.

That is, electrodes 2 and 3 made of tungsten, molybdenum, etc., a conductive ceramic member 7, and a trigger terminal 8 are attached to a frit glass 1 in advance on a base 10.
A cylindrical envelope 1' made of, for example, quartz glass and having an open end is placed on top of the cylindrical envelope 1'.
After placing, evacuation, and gas filling, the envelope 1' and the base 10 are hermetically sealed with a frit glass 11 to complete the process.

Since the electrodes 2 and 3 are sealed to one end of the envelope 1', the flash discharge tube obtained as described above can be regarded as a point light source similar to the conventional example shown in FIG. 5a. Due to the small size and the presence of the conductive ceramic member 7 in the envelope 1', the electrode 2,
The discharge between the spaces 9a, 3 along the conductive ceramic member 7 is almost unaffected by the state inside the envelope 1.
9b, that is, in a U-shape as shown by the broken line in FIG.

As mentioned earlier, if there is a gap between the conductive ceramic member 7 and the envelope 1', discharge will occur through the gap instead of forming the U-shaped discharge path as described above. In order to eliminate this fear and form a safe and stable discharge path, it is necessary to hermetically seal the conductive ceramic member 7 to the envelope 1' either directly or through an adhesive member such as frit glass. desirable.

On the other hand, let us now examine the electrical characteristics of the conductive ceramic member 7 that divides the interior of the envelope 1' into a plurality of spaces and is also used as a trigger electrode.

As is well known, conductive ceramics are composites of ceramic and metal that have excellent heat resistance and various specific resistances.The present inventors used various conductive ceramic members as the conductive ceramic member 7 in the present invention. Then, we conducted a luminescence experiment.

Fig. 2 is a diagram showing the results of the above-mentioned luminescence experiment, where the horizontal axis shows the specific resistance value of the conductive ceramic used, and the vertical axis shows the luminescence starting voltage of the flash discharge tube according to the present invention shown in Fig. 1. It is a light emission characteristic diagram.

The flash discharge tube used in this experiment used a hard glass container with an outer diameter of 4.5 mm, a wall thickness of 0.5 mm, and a height of 8 mm as the envelope 1, the filled gas was xenon gas, the pressure was 700 Torr, and the conductive Ceramic member 7
The shape was a plate with a wall thickness of 0.4 mm and a height of 6 mm, and the base used had an outer diameter of 4.5 mm and a height of 1.5 mm.

Now, as is clear from the light emission characteristic diagram in FIG. 2, a large difference occurs in the light emission starting voltage due to a difference in the specific resistance value of the conductive ceramic member 7.

That is, in the case of the above-mentioned flash discharge tube, the emission starting voltage is determined by the specific resistance of the conductive ceramic member 7.
It has a characteristic that it has a minimum value around 50KΩcm and increases even if it is larger or smaller than that, and if it is less than 3KΩcm, it does not emit light, and if it exceeds 10KΩcm, the emission starting voltage increases rapidly.

This means that if the specific resistance is too low, the trigger terminal 8
Even if a trigger voltage is applied through the xenon gas, sufficient trigger energy cannot be supplied to the encapsulated xenon gas, and a larger input energy is required to emit light. On the other hand, if an attempt is made to supply a larger input energy, a short circuit will occur between the conductive ceramic member 7 and the electrodes 2 and 3, resulting in non-emission.

On the other hand, if the specific resistance is too high, the resistance loss of the trigger energy supplied from the trigger terminal 8 will be extremely large, and as in the previous case, in order to supply sufficient energy, a large amount of input energy must be applied between the main electrodes of the flash discharge tube. This is thought to be because the voltage must be applied.

As a result, in order to efficiently obtain stable light emission in the flash discharge tube according to the present invention having the specifications mentioned above, it is necessary to use a conductive ceramic member 7 with a specific resistance value in the range of 3KΩcm to 10KΩcm. I can understand good things.

Figure 3 a and b are figure number 7 in the embodiment of Figure 1.
2 is a perspective view showing another embodiment of the conductive ceramic member 7 shown in FIG. In the example shown in FIG. 1B, there are four spaces, unlike the two spaces 9a and 9b in the embodiment shown in FIG.

That is, the conductive ceramic member 7 of FIG. 3a is intended to concentrate the trigger voltage supply from the trigger terminal 8 to the center of the envelope 1.
In other words, the discharge near the inner circumferential surface of the envelope 1 is made difficult to occur, and even if the degree of airtightness between the envelope 1 and the conductive ceramic member 7 is somewhat poor, a short circuit does not occur easily and a U-shaped discharge occurs. This was an attempt to form a road more reliably.

Further, the conductive ceramic member 7 in FIG. 3b divides the inside of the envelope 1 into four spaces, and serves as a discharge path.
The idea was to form a discharge path with two consecutive letter shapes, and if the optimal discharge path length could be determined, the height of the discharge tube could be lowered, making it possible to make it more compact.

In addition, when examining the luminous characteristics of a discharge tube in which the inside of the envelope 1' is divided into four spaces by the conductive ceramic member 7, it was found that the length of the discharge path was set to the length with the highest luminous efficiency, that is, the first space. When the length was set to be equivalent to that of the example shown in the figure, characteristics substantially equal to those shown in FIG. 2 were obtained.

As a result, when determining the length of the discharge path in consideration of luminous efficiency and controlling the division state within the envelope 1',
The conductive ceramic member 7 has a specific resistance of 3KΩ.
It can be said that if a value in the range of cm to 10KΩcm is selected, stable light emission can be obtained efficiently.

Furthermore, although not shown in the drawings, it goes without saying that the shape of the conductive ceramic member 7 as described above can be arbitrarily set to various shapes, such as a spiral shape, in order to form a desired discharge vessel.

Effects of the invention As described above, the flash discharge tube according to the invention has two electrodes sealed at one end of the envelope and connected in series within the envelope by a conductive ceramic member that also serves as a trigger electrode. Since it is divided into multiple spaces, it has the effect of realizing the discharge path in a compact form that can be regarded as a point light source, considering the most preferable luminous efficiency. Since it can be formed along the member, it has the effect of stably emitting light without changing the discharge path.

Further, since most of the thermal shock when the trigger voltage is supplied is applied to the conductive ceramic member rather than the envelope, a longer life can be achieved.
That is, it is possible to provide a flash discharge tube that does not suffer from the conventional problems such as breakage of the trigger electrode and occurrence of cracks in the envelope. Incidentally, the conductive ceramic itself is extremely resistant to thermal shock and does not cause any problems.

Furthermore, by using an insulating ceramic member other than the central part of the conductive ceramic member, the discharge path can be formed in the central part of the envelope.
There is also the advantage that there is no need for airtight sealing between the envelope and the conductive ceramic member using fritted glass or the like, which greatly simplifies the manufacturing process.

Furthermore, when considering its use in combination with a reflective umbrella, it can be regarded as a point light source, and as a result, the design of the reflective umbrella can be made extremely easy and compact, and its light distribution characteristics can also be improved. are doing.

[Brief explanation of drawings]

FIGS. 1a and 1b are a vertical cross-sectional view and a right side view showing an embodiment of a flash discharge tube according to the present invention, respectively, and FIG. 2 is a diagram of light emission characteristics when various types of conductive ceramic members 7 are used. 3a and 3b are perspective views showing other examples of the conductive ceramic member 7, and FIGS. 4a and 4b, and 5a, b, and c are front views showing conventionally known flash discharge tubes, respectively. be. 1'... Cylindrical envelope, 2... Anode, 3... Cathode,
7... Conductive ceramic member, 8... Trigger terminal, 9a, 9b... Space, 10... Base, 11...
...adhesive material.

Claims (1)

[Claims for Utility Model Registration] (1) A cylindrical envelope whose one end is an open end, an anode and a cathode, and the inside of the envelope is divided into a plurality of spaces connected in series forming a discharge path. At the same time, the specific resistance also functions as a trigger electrode.
A conductive ceramic member having a resistance within the range of 3KΩcm to 10MΩcm, and a base body hermetically sealed to the open end so as to keep the two electrodes and the conductive ceramic member airtight and to seal a predetermined gas into the envelope. and a trigger terminal inserted into the base in an airtight state and electrically connected to the conductive ceramic member. (2) The conductive ceramic material has a specific resistance of 3KΩcm.
A part made of conductive ceramic and a part made of insulating ceramic are integrated, and the part made of conductive ceramic has a conductive ceramic part that is in the range of 10 MΩcm to 10 MΩcm. and the portions made of insulating ceramic are located on both sides of the conductive ceramic close to the inner periphery of the envelope and constitute the ends of the conductive ceramic member. The flash discharge tube described in .