JPH0527794Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a flash tube, and particularly to a flash tube suitable for use as an illumination light source for photographing with a fundus camera.

(Prior Art) Conventionally, flash tubes used as illumination light sources for photographing with fundus cameras have been made by bending a long straight glass tube into a U-shape; A ring-shaped light-emitting glass tube is created by curving glass tubes that used to extend long in opposite directions toward each other from the middle so that the forward portions of the curved lines cross each other in a three-dimensional manner. There is something formed in the tube part.

(Problem that the invention aims to solve) By the way, fundus cameras are designed to illuminate the fundus with a ring-shaped illumination light (also called a light ring) when taking pictures, but the conventional U-shaped flash In the tube, since the glass tube part that generates the flash is U-shaped, the illumination light illuminating the fundus of the eye does not form a ring shape, which is disadvantageous in that the fundus of the eye cannot be evenly illuminated during photography. On the other hand, glass tubes that extend long in opposite directions toward both end portions are curved toward each other from the middle, and the forward portions in the curved direction cross each other, and the ring-shaped light-emitting glass tube portion is formed by removing both end portions. A flash tube formed in a glass tube can provide ring-shaped illumination light, but in the case of this flash tube, the light intensity of the observation illumination light source, which is placed conjugately with the flash tube through a lens, is Since the light is attenuated by the lens action of the tube wall portions that cross each other and overlap, there is a problem that the fundus cannot be evenly illuminated during observation.
Additionally, this conventional flash tube with a ring-shaped light-emitting glass tube section has the disadvantage that the thickness of the illumination system in the optical axis direction is larger than that of a flash tube with a straight glass tube curved into a U-shape. There is also.

The present invention was devised in view of the above circumstances, and its purpose is to form a ring-shaped light-emitting glass tube at both ends with discharge electrodes without increasing the thickness of the illumination system in the optical axis direction. It can be formed on the part of the glass tube except for the part of the glass tube, and it is possible to avoid as much as possible attenuation of the light intensity of the illumination light source for observation during observation, and it is also possible to form a ring-shaped ring for photography with less uneven illumination during photography. It is an object of the present invention to provide a flash tube which can obtain illumination light and is suitable for use as an illumination light source for photographing with a fundus camera.

(Means for Solving the Problems) The features of the present invention are that in order to achieve the above problems,
In the flash tube, a glass tube section on the left side and a glass tube section on the right side are curved into a semicircular shape, with the glass tube section on the left side and the glass tube section on the right side bordering approximately the center part of the glass tube, which has discharge electrodes at both ends. Each wall portion on the side closer to the discharge electrode with the right side glass portion has a constricted shape that is fused to each other, and the portion of the glass tube excluding both end portions having the discharge electrode becomes a ring-shaped light emitting glass tube portion. It's where you are.

(Function) According to the present invention, since the ring-shaped light-emitting glass tube section is formed in the glass tube excluding both end portions where the discharge electrodes are provided, ring-shaped illumination light with less uneven illumination can be used during photography. You can definitely get
In addition, a ring-shaped light-emitting glass tube can be created by curving the glass tubes, which extend in opposite directions toward both ends like a conventional flash tube, in the middle toward each other, and making the front portions of the curved directions cross each other. Since it is not a structure in which the ring-shaped light-emitting glass tube is formed on both ends of the glass tube except for the ends with the discharge electrodes, it is possible to form the ring-shaped light-emitting glass tube on both ends of the glass tube with the discharge electrodes without increasing the thickness of the illumination system in the optical axis direction. It can be formed in the removed portion of the glass tube, and it is possible to avoid attenuation of the light intensity of the observation illumination light source during observation.

(Example) Hereinafter, an example of a flash tube according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of the optical system of a fundus camera using a flash tube according to the present invention. To briefly explain this diagram, E is the eye to be examined, F is the fundus of the eye to be examined, and C is the cornea of the eye to be examined, I is the pupil, 1 is the illumination system for illuminating the fundus F,
2 is an imaging system for obtaining an image of the fundus F, and 3 is the fundus F.
This is an observation system for observing the image of The illumination system 1 includes an observation light source 4 as an illumination light source for observation and a photographing light source 5 as an illumination light source for photographing. The observation light source 4 is arranged conjugately with the photographing light source 5 via the relay lens 6. The photographing light source 5 is provided close to the ring slit 7. This ring slit 7 is illuminated by an observation light source 4 and a photographing light source 5, and the light beam passing through the ring slit 7 is reflected by a total reflection mirror 8 and a relay lens 9 into a perforated mirror that forms part of the photographing system 2. Guided by 10. The illumination light reflected by the perforated mirror 10 is guided to the fundus F of the eye E to be examined via the objective lens 11.

The ring slit 7 is arranged conjugately with the pupil I of the eye E to be examined with respect to the objective lens 11, and a light ring as an image of the ring slit 7 is formed in the pupil I. The fundus F of the eye E to be examined is illuminated by an observation illumination light beam during observation, and is illuminated by a photography illumination light beam during photography. The reflected light flux from the fundus F is taken out from the center of the pupil I, and passes through the focusing lens 12 and the imaging lens 13 to the film surface 1.
4, or guided to observation system 3.

As the photographing light source 5, a flash tube 15 having a shape as shown in FIGS. 2 and 3 is used. This flash tube 15
The glass tube section on the left side and the glass tube section on the right side are curved into a semicircular shape, with the glass tube section on the left side and the glass tube section on the right side bordering approximately the center part of the glass tube, which has discharge electrodes at both ends, which will be described later.
5 has a constricted shape in which the walls 16, 16 on the side closer to the discharge electrode of the left glass tube portion and the right glass tube portion are fused to each other, excluding both end portions having discharge electrodes, which will be described later. The tube portion is a ring-shaped luminescent glass tube portion 17. Both ends of the glass tube are used as legs 18, 18 for discharge electrodes, and 19, 19 are discharge electrodes. The legs 18, 18 are attached to a circuit board 20.

A trigger wire 22 for starting discharge is wound around the wall of the flash tube 15. This trigger wire 22 is drawn out from one discharge electrode 19 toward the outside, and is made into a half-wrap in the circumferential direction of the leg portion 18 on the side of one discharge electrode 19, and is wound around the wall on the side of one discharge electrode 19. It is guided through the section 16 to the fusion section, and guided into the circular hole 23 of the ring-shaped light emitting glass tube section 17 along the fusion section. Then, the trigger wire 22 passes through the circular hole 23, is wound around the left half tube wall of the ring-shaped light emitting glass tube section 17 in the horizontal direction, and is again guided into the circular hole 23, and is guided again into the circular hole 23. It passes through the hole 23 and is led to the top, where it is hooked onto a protrusion 24 formed at the top. After that, the trigger wire 22 is connected to the circular hole 23 again.
It passes through the circular hole, is wound around the right half tube wall of the ring-shaped light emitting glass tube part 17 in a horizontal direction, and is again guided to the circular hole 23, and then connected to the other discharge electrode. 19 through the wall 16 on the side of the discharge electrode 19 to the welded part, and along this welded part it is guided to the leg part 18 on the other discharge electrode 19 side, and the leg part on the other discharge electrode 19 side. The electrode 18 is wound half a turn in the circumferential direction and connected to the other discharge electrode 19 . Note that 21 is a trigger lead line.

When a high pulse voltage is applied to the trigger wire 22 in order to start flashing from the flash tube 15 having such a shape, a nearly circular closed discharge locus is generated as shown by the broken line A, and a ring-shaped flash B is obtained. It will be done.

(Effect of the invention) As explained above, in the present invention, the glass tube part on the left side and the glass tube part on the right side are curved into a semicircular shape with the approximate center part of the glass tube having discharge electrodes at both ends as a boundary. , the glass tube has a constricted shape in which wall portions of the left glass tube portion and the right glass portion on the side closer to the discharge electrode are fused to each other;
Since the portion of the glass tube excluding both end portions having the discharge electrodes is a ring-shaped light-emitting glass tube portion, it is possible to reliably obtain ring-shaped illumination light with less uneven illumination during photography. , a ring-shaped light-emitting glass tube section is created by bending glass tubes that extend long in opposite directions toward both end portions, like a conventional flash tube, toward each other from the middle, and making the forward portions of the curved directions cross each other. Since it is not a structure in which the ring-shaped light-emitting glass tube is formed on the glass tube except for both end portions having the discharge electrodes, the ring-shaped light-emitting glass tube portion can be formed in the glass tube portion except for the both end portions having the discharge electrodes without increasing the thickness of the illumination system in the optical axis direction. It can be formed in the glass tube section, and it is possible to avoid attenuation of the light intensity of the observation illumination light source during observation.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of an optical system of a fundus camera using a flash tube according to the present invention, Fig. 2 is a plan view of a flash tube according to the present invention, and Fig. 3 is a diagram showing a flash tube according to the present invention. FIG. 4...Observation light source, 5...Photography light source, 15...Flash tube, 16...Wall part, 17...Ring-shaped light emitting glass tube part, 19...Discharge electrode, 22...Trigger line, I...Pupil .

Claims (1)

[Claims for Utility Model Registration] (1) A glass tube portion on the left side and a glass tube portion on the right side are curved into a semicircular shape with a substantially central portion of the glass tube having discharge electrodes at both end portions as a border, has a constricted shape in which the walls of the left glass tube portion and the right glass portion on the side closer to the discharge electrode are fused to each other, and the portion of the glass tube excluding both end portions having the discharge electrode is a ring. A flash tube characterized by having a shaped luminous glass tube section. (2) The flash tube according to claim 1, wherein a trigger wire for starting discharge is guided along the fused portion of the glass tube.