JPH0432497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a compact high-pressure discharge lamp device that combines a compact high-pressure discharge lamp and a reflector.

Conventional configurations and their problems Small spotlights are used as a type of energy-saving lighting for shop windows and precious metal product lights.

Traditionally, incandescent light bulbs have been widely used as small spot lights, but in recent years small high-pressure discharge lamps such as short-arc xenon discharge lamps, ultra-high pressure mercury lamps, and metal halide lamps, which have high brightness and are easy to obtain spot illumination, have been used for energy saving purposes. It has come to be used. In order to fully utilize the effect of spot lighting with high brightness, there is a need to develop a compact high-pressure discharge lamp device in which the arc tube and reflector are as small as possible, and which has less uneven illuminance.

By the way, for large high pressure discharge lamps of 200W or more,
The arc tube is held within an outer tube provided with an aluminum reflective film, and an inert gas is sealed inside the outer tube. Since such a large reflective high pressure discharge lamp has a very high luminous flux value, it is installed and used at a location relatively far away from the object to be irradiated.

On the other hand, in order to obtain high-intensity and efficient spot illumination with a small high-pressure discharge lamp, it is necessary to irradiate the object from a relatively close location. Therefore, in small-sized high-pressure discharge lamps, sufficient measures must be taken to deal with light distribution, particularly uneven illuminance on the irradiation surface, which has not been a problem in conventional large-sized reflective high-pressure discharge lamps.

For large reflective high pressure discharge lamps with outer tubes,
Because the arc tube is large, the reflected light is blocked by the arc tube support, the arc tube itself, and especially the arc tube sealing part, making it difficult to obtain uniform light distribution. By installing it in a high place, uneven illumination was alleviated, and by providing a diffusion film on the front of the outer tube, a uniform light distribution was obtained.

However, in the case of the compact high-pressure discharge lamp targeted by the present invention, the ratio of the sealed part to the light emitting part of the arc tube is large, so it is not sufficient to shield reflected light by the sealed part of the arc tube or the arc tube itself. If appropriate measures are not taken, a problem will occur in which illuminance becomes uneven on the irradiated surface.

Purpose of the Invention The present invention has been made in view of the above circumstances, and it is possible to make the light distribution uniform without the reflected light from the reflecting mirror being blocked by the arc tube sealing part, etc., and to improve the illumination surface. The present invention provides a compact high-pressure discharge lamp device with less uneven illuminance.

Structure of the Invention The present invention provides an arc tube having an oval or spherical shape,
The wall thickness near the center of the arc tube is maximized, and as it approaches the end of the arc tube, the wall thickness is continuously thinned to a minimum wall thickness of 1 mm or more, and the lens action directs light in the direction of the larger wall thickness. By refracting the light to increase the amount of light emitted at the center of the arc tube and effectively utilizing the light reflected from the reflecting mirror, uniform light distribution is achieved.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows a combination of a 55W compact short-arc xenon discharge lamp and a reflector. At both ends of the arc tube 1 made of quartz glass, electrodes 2 and 3 made of high melting point material such as tungsten are used. They are sealed via metal foils 4 and 5 to form sealed parts 6 and 7. Lead wires 8 and 9 are connected to the ends of these metal foils 4 and 5. Metal caps 10 and 11 are provided at both ends of the arc tube 1. The interior of the arc tube 1 is filled with xenon 12 at a pressure of about 15 atmospheres to constitute a short arc xenon discharge lamp.

Such a small short arc xenon discharge lamp has a small short arc xenon discharge lamp device fixed to a predetermined position of a reflector 13 with bolts 14 or cement, and a voltage is applied to lead wires 8 and 9. The light will turn on. The light emitting portion of the arc tube 1 has an ellipsoidal or spherical shape in order to smoothly generate gas convection within the discharge space and provide pressure resistance. In addition, the sealing parts 6 and 7 are made relatively long in order to prevent the metal foils 4 and 5 from being oxidized due to lighting in free air and an increase in the temperature of the arc tube, resulting in loss of airtightness and leakage. ing.

FIG. 2 shows a cross-sectional view of such an arc tube, and the arc tube 1 is constructed so that the wall thickness distribution of the light emitting part is different. In other words, the wall thickness near the center of the arc tube 1
T _a is maximized, wall thickness t _b near the end of arc tube 1 is minimized, and the wall thickness changes continuously from wall thickness T _a to wall thickness t _b . Since the arc tube has an ellipsoidal or spherical shape, such thickness changes occur easily, and a lens-like thickness is formed.
Note that the minimum wall thickness t _b must take into account the type of rare gas and additives to be sealed and the internal pressure depending on the wattage. In the compact high-pressure discharge lamp device according to the present invention, in order to raise the temperature of the arc tube by lighting the arc tube in free air and increase the pressure or vapor pressure of the enclosed material at the time of lighting, the arc tube has an outer tube. It is designed to be smaller than the general type that uses arc tubes, and the internal pressure of the arc tube reaches 25 to 40 atmospheres or more. In addition, in consideration of the increase in lamp voltage, the deterioration of the pressure resistance of the tube wall, and ensuring safety when used in free air, the arc tube must have a pressure resistance of 60 atmospheres. Therefore, it was confirmed through experiments that the minimum wall thickness _tb should be 1 mm or more, with a pressure resistance of 60 atm as the limit value.

By having such a wall thickness distribution, a lens-like wall thickness is formed, which refracts light in the direction of the larger wall thickness, making it possible to improve the light distribution by increasing the amount of light emitted from the center of the arc tube. . The principle will be explained in detail using FIGS. 3A to 3C. Figure 3A shows the case where the arc tube shape is ellipsoidal or spherical and there is no change in wall thickness, and Figure 3B shows the same arc tube shape as above.
If the wall thickness at the center is smaller than at the ends, Figure 3C
1 and 2 relate to the present embodiment, and respectively show cases in which the arc tube has an elliptic spherical shape or a spherical shape similar to the above-mentioned arc tube shape, and the center portion is thicker than the end portions. In FIGS. 3A to 3C, explanation will be given by considering a case where the inner surface of the arc tube has the same radius of curvature and the light OA is emitted from the center of the arc tube in the backward direction.

In the case of Fig. 3 A, the ray OA incident at an angle of incidence θ
is once refracted within the quartz glass of the arc tube 12 at an angle smaller than the incident angle θ, becoming a ray AB, and then further refracted at an angle larger than the angle of incidence of the ray AB as it exits from point B, becoming a ray BC. released. That is, in the case of Figure 3A,
The refracted light BC is slightly eccentric to the center of the OAD line, which is an extension of the incident light in the OA direction, but is emitted at approximately the same angle of incidence θ of the incident light OA.

In the case of FIG. 3B, the light ray OA incident at the same angle of incidence as in FIG. 3A is refracted within the quartz glass of the arc tube 13 at the same angle as in the case of FIG.
It becomes AB. The process up to the light ray OAB is the same as in Figure 3 A, but since the upper part of the figure is thicker, the light going out from point B is refracted in the direction of the thicker wall. Due to the lens effect, the light beam OA is refracted at an angle greater than the incident angle and is emitted upward as a light beam BC'. That is, it spreads to the end of the arc tube 13 and is emitted.

In the case of FIG. 3C, that is, in the case of the embodiment of the present invention, the light ray OA incident at the same angle of incidence as in the cases of FIGS. is refracted to the same angle as in the configuration AB. The process up to the light ray OAB is the same as in Figure 3 A and B, but since the lower part of the diagram is formed with a large wall thickness, the light exiting from point B is directed in the direction of the large wall thickness. Due to the lens effect, the light beam is refracted at an angle smaller than the incident angle of the light beam OA and is emitted downward as a light beam BC''. In other words, it is concentrated in the center of the arc tube 1 and emitted. .

In the above explanation, a single ray of light emitted from near the center of the arc tube was explained, and the inner surface of the arc tube was considered to be an elliptical sphere that approximated the actual example. Even if we consider the case of a spherical shape, in the case of an elliptical spherical or spherical one in which the wall thickness near the center of the arc tube is increased, it is easy to concentrate toward the center of the arc tube due to the lens effect. be understood.

Next, in FIGS. 4A to 4C, we will explain the state of emitted light and reflected light when an arc tube with an ellipsoidal or spherical inner surface and a different wall thickness distribution is assembled into a reflector. do. A case will be described in which the discharge center points of the curved surface of the reflecting mirror 13 are made to coincide with each other.

FIG. 4A shows a case where there is no change in the wall thickness of the arc tube, and the emitted light OE emitted from the end of the arc tube toward the rear of the reflector becomes a light ray EE' and is reflected forward. However, in the case of a small high-pressure discharge lamp in which the ratio of the sealing part to the light emitting part of the arc tube is large, the light beam EE' is likely to be blocked by the sealing part, and there is a strong tendency to cause uneven illuminance on the irradiated surface. Furthermore, in the case of a compact reflecting mirror, the synchrotron radiation OF emitted from the end of the arc tube toward the front of the reflecting mirror does not enter the reflecting surface and is directly irradiated as light, causing uneven illuminance. Furthermore, the radiation angle and illuminance vary greatly depending on the mounting position of the arc tube, which tends to cause variations in quality.

Figure 4B shows the case where the thickness of the center part of the arc tube is smaller than that of the end part of the arc tube, and the light is refracted and emitted from the arc tube toward the end. The emitted synchrotron radiation OE is reflected on the bottom side of the reflector to become a light ray EE′, and then reflected again at the front surface to become a light ray E′E″ and reflected forward.The light EE′ is blocked by the arc tube. It is difficult to design a reflecting mirror to obtain uniform light distribution because the light rays are reflected back to the front and become light rays E′E″. In addition, since the synchrotron radiation OF emitted from the end of the arc tube toward the front of the reflector spreads to the end of the arc tube, in the case of a compact reflector,
It is irradiated directly as light without entering a reflective surface,
This causes more uneven illuminance than in the case of FIG. 4A. Furthermore, the radiation angle and illuminance vary greatly depending on the mounting position of the arc tube, and the variation in quality is greater than in the case of FIG. 4A.

FIG. 4C shows an example of the present invention, that is, a case where the thickness of the central part of the arc tube is larger than that of the end parts.
Since the light emitted from the arc tube is refracted toward the center, the emitted light OE and OF emitted from the end of the arc tube toward the rear and front of the reflector are reflected less than in the cases shown in Figure 4 A and B. Since the reflected light is refracted toward the center of the mirror, there is less blocking of the reflected light by the arc tube or sealing part, and even in the case of a compact reflecting mirror, the proportion of direct light that does not enter the reflecting surface is small, so it is difficult to reach the irradiated surface. Does not cause uneven illumination. Furthermore, since the light emitted from the arc tube is efficiently reflected by the reflecting mirror, the relative illuminance increases, and compared to the cases shown in Figure 4 A and B, there are fewer complex reflections and the compact design allows for uniform light distribution. It is easy to design a reflective mirror.

Figure 5 shows the results of improving the light distribution characteristics of a small short arc xenon discharge lamp device manufactured based on the above principle. The small short arc xenon discharge lamp that we manufactured is
The power consumption is 55W, and the arc tube is made of elliptical spherical quartz glass with a maximum inner diameter of 8 mm, and 15 atm of xenon is sealed inside. The length is 25mm. and,
Three types of arc tubes with different wall thickness distributions were fabricated. In other words, (1) the arc tube has a wall thickness of t _a = t _{b of} 1.2 mm and no change in wall thickness, (2) the wall thickness of the center part is t _a = 1 mm, and the ends become thicker continuously, and the end wall thickness t _b = 2mm arc tube, (3)
The wall thickness at the center part is t _a = 2 mm, and the end parts are continuously thinned, and each arc tube with an end wall thickness t _b = 1 mm is incorporated with a parabolic curved reflector with an opening diameter of 40 mm and a bottom height of 45 mm. The light distribution characteristics directly below 1.5m when
As shown in the figure. In the figure, the results for each of the above cases (1), (2), and (3) are represented by curves.

As is clear from FIG. 5, in the relative illuminance of the irradiated surface, the illuminance unevenness near the center of the curve was large, and the radiation angle d was also wide, resulting in an unclear pattern. On the other hand, in the curve, the relative illuminance of the irradiated surface was made uniform, the illuminance level increased by about 30%, and the radiation angle d also satisfied the design value, resulting in a clear pattern.

Similar results were also obtained when experiments were conducted using a small ultra-high-pressure mercury lamp, in which mercury and argon were sealed inside the arc tube, and a small metal halide lamp, in which tin halide, mercury, and argon were sealed. Furthermore, similar results were obtained when experiments were conducted over a wide range of t _a /t _b from 1.5 to 3.0.

Effects of the Invention As explained above, the present invention makes the shape of the light emitting part of the arc tube elliptical or spherical, maximizes the wall thickness near the center of the arc tube, and increases the wall thickness as it approaches the end of the arc tube. By continuously thinning the wall to a minimum of 1mm and using lens action to refract the light in the direction of the thicker wall, increasing the amount of light emitted from the center of the arc tube, the reflected light can be effectively used with a compact reflector. It is possible to provide a compact high-pressure discharge lamp device that can be used to achieve uniform light distribution, illuminance level, and clear pattern.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a small high-pressure discharge lamp device according to an embodiment of the present invention, FIG. 2 is a partial sectional view of the small discharge lamp, and FIGS. 3 A to C are small high-pressure discharge lamp devices according to the present invention. Figures 4A to 4C are for comparing and explaining the lens effect of a discharge lamp with other lens effects. , and FIG. 5 are diagrams showing the light distribution characteristics of various small high pressure discharge lamps. 1... Arc tube, 2, 3... Electrode, 6, 7... Sealing part, 8, 9... Lead wire, 10, 11... Base, 13... Reflector.

Claims (1)

[Claims] 1. In a small high-pressure discharge lamp device in which a small high-pressure discharge lamp is equipped with a light-emitting tube made of glass having electrodes at both ends and a light-emitting portion having an ellipsoidal or spherical shape, the central portion of the light-emitting tube is incorporated into a reflector. A compact high-pressure discharge lamp device characterized in that the wall thickness near the end of the arc tube is maximized, and the wall thickness is continuously thinned as it approaches the end of the arc tube, so that the minimum wall thickness is 1 mm or more.