JP2532234Y2 - Light source unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light source unit having improved light collection efficiency with respect to an optical transmission rod.

[Background of the invention]

A light source unit using an optical transmission rod made of a quartz glass rod, an optical glass rod, a silicone resin rod, an acrylic resin rod, or the like has been proposed (JP-A-62-1).
42465). Here, a light source unit suitable as a light source for office equipment such as an image scanner, an optical printer, a monochrome copying machine, a color copying machine, and a facsimile is disclosed. On the rod for light transmission used in this light source unit, a reflection fringe made of fine powder having a high refractive index was attached in the form of fine stripes directly in the longitudinal direction on the outer peripheral surface of the rod, and was incident on the rod from a lamp. The light beam is emitted outside the rod at a right angle to the light transmission direction of the rod, the light amount level of the emitted light is large, the light amount is uniform, linear light without unevenness and bias, and the emission beam angle is small. The light is emitted as a light flux close to a parallel light beam.

In the light source unit described above, a reflector is generally used so that light emitted from the light source is efficiently incident on the end face of the light transmission rod by the reflector. Therefore, when a reflecting mirror is used as a light source of a light source unit using a light transmission rod, how to improve the light collection efficiency has been an important issue.

[Problems to be solved by the invention]

As a method of narrowing a beam emitted from a light source to a relatively short focal point by a reflecting mirror, a wide-angle floodlighting for projection or general irradiation such as a projector is mainly used. In such a case, it is a necessary condition to improve the light collection efficiency of the beam, but since the emitted light distribution must be uniform and the shadow of the filament lead must not be projected, a reflecting mirror must be used. In other words, the overall characteristics must be balanced as a compromise design that takes into account diffusibility such as so-called multi-configuration (multi-mirror) or stippling. Therefore, in terms of light-collecting efficiency, the light-collecting efficiency is not always sufficient, and it is not a suitable design for inputting the emitted light beam to the optical transmission rod. I was

[Means and actions for solving the problems]

The present invention has been made in view of the above, and in order to improve the light-collecting efficiency and efficiently input a light beam to the optical transmission rod, the light-condensing angle is widened, and the output beam to the optical transmission rod is increased. An object of the present invention is to provide a light source unit provided with a reflecting mirror in which a convergence angle is in a range that does not increase loss due to Fresnel reflection on an incident surface of a light transmission rod.

〔Example〕

Hereinafter, the light source unit according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment according to the present invention.
A tungsten filament 2 is provided so as to be located at a first focal point of a reflecting mirror 3 made of, for example, heat-resistant glass. The reflecting mirror 3 has a spheroidal shape coated with a mirror surface, and is located in front of the electric bulb 1 by reflecting light generated by the filament 2 and condensing the reflected light at a secondary focus F. Light is incident on the light transmission rod 4. The internal structure of the light bulb 1 has the same configuration as that generally known.

The reflecting mirror 3 has a mounting part whose central part projects rearward in a cylindrical shape.
3a, and the two are integrally fixed by cement 5 in a state where the base 1a of the electric bulb 1 is inserted into the mounting portion 3a.

The reflecting mirror 3 has a condensing angle (a value indicating the outer angle formed by the top of a cone formed by the opening of the reflecting mirror 3 which is a divided spheroid and the light source 2 (focal point) of the lamp 1). Is set to a wide angle (at least 265 deg. Or more), and the convergence angle 2θ of the output beam to the optical transmission rod 4 is in a range (near 60 deg.) In which the loss due to Fresnel reflection at the incident surface of the optical transmission rod 4 is not increased. The curvature and shape of the short focus ellipse are set. Here, the convergence angle 2θ is preferable because the Fresnel reflection is minimized at the above-mentioned value near 60 °. However, in actual use, the convergence angle 2θ is smaller than about 65 °.
If it is θ, there is no particular problem.

On the other hand, the ratio (depth ratio) of the depth h to the aperture diameter d of the reflecting mirror is set to 0.65 or more to make the depth deep.

Here, the converging angle 2φ, the convergence angle 2θ, and the depth ratio h /
I would like to mention how the critical value of d was specified. First, with respect to the converging angle 2φ, there is a fact that, when the converging angle 2φ increases, the condensing efficiency of the outgoing beam light also increases almost in proportion thereto. That is, it is desired that the converging angle 2φ is as large as possible. On the other hand, regarding the convergence angle 2θ, there is a fact that, as described above, a range in which the loss due to Fresnel reflection of the beam emitted to the optical transmission rod 4 at the rod incident surface is not increased, that is, 65 ° or less is desirable. It should be noted here that when the converging angle 2φ is increased, the convergence angle 2θ is also increased accordingly. That is, if the condensing angle 2φ is simply widened, there is a fact that the convergence angle 2θ becomes so large that the loss due to Fresnel reflection cannot be ignored. Conversely, when the condensing angle 2φ is reduced, the converging angle 2θ is reduced accordingly, and there is no problem in particular regarding Fresnel reflection, but there is a problem in that the condensing efficiency is reduced. Also, the depth ratio
If h / d is not increased to some extent, for example, there is a problem that the tip 1b of the bulb 1 projects from the opening of the reflecting mirror 3. However, increasing the depth ratio h / d means that the condensing angle 2φ also increases, which also causes the above-described problem regarding the Fresnel reflection at the convergence angle 2θ. Conversely, when the depth ratio h / d is reduced, the convergence angle 2θ is also reduced accordingly, and there is no problem particularly with respect to Fresnel reflection, but there is a problem that the light collection efficiency is reduced. In addition, there are limitations of current manufacturing technology. This is the limit of the process of depositing the coating on the surface of the reflecting mirror. At present, it is difficult to deposit the coating evenly when the converging angle 2φ is too large. However, considering the manufacturing limit and simply reducing the light collection angle 2φ, there is no particular problem regarding the convergence angle 2θ, but not only does the light collection efficiency decrease, but also the depth ratio h / d decreases. For example, at a certain point, the above-described problem of the protrusion of the light bulb chip portion occurs. From these points, it is possible to increase the light-collecting efficiency by taking into account the limitations of the manufacturing technology for uniformly depositing the coating on the reflector surface while keeping the convergence angle 2θ at 65 ° or less in order to consider Fresnel reflection. The value obtained as a result of increasing the converging angle 2φ so as to be as large as possible and increasing the depth ratio h / d in order to avoid the above-described problems and the like is the above-described critical value. That is, the focusing angle 2φ of the reflecting mirror 2 is set to 265de.
g. or more, the depth ratio h / d is 0.65 or more, and the convergence angle 2θ of the output beam to the optical transmission rod is 65 deg. or less.

In FIG. 2, WD indicates the working distance, and α indicates the spread angle of the beam due to the filament area.

In the above configuration, the light generated in the filament 2 becomes the emitted light directly radiated forward, and the emitted light reflected forward by the reflecting mirror 3.
For these emitted lights, the converging angle 2φ of the reflecting mirror 3 and the converging angle 2θ of the outgoing beam are set as described above, so that the converging efficiency of the outgoing beam light is improved almost in proportion to the increase of the converging angle. can do. Further, since the depth ratio is 0.65 or more, the tip 1b of the bulb 1 may protrude from the opening of the reflector 3 regardless of the finished dimension of the tip 1b of the bulb 1 combined with the reflector 3. Absent. Therefore, the entire optical system can be configured extremely efficiently and easily by disposing a convex condensing lens, an explosion-proof cover, a filter, and other optical members near the opening of the reflecting mirror 3. it can.

Although not shown, in the embodiment in which the reflective mirror 3 is coated with a heat ray transmitting multilayer film, the area of the reflected light 3 increases as the condensing angle becomes wider, so that the area from the bulb 1 to the rear of the reflective mirror 3 is increased. Since the amount of transmitted heat rays increases, the number of heat rays emitted from the bulb 1 toward the light transmission rod 4 decreases. For this reason, a very advantageous thing can be obtained also in terms of heat measures.

According to an experiment conducted by the applicant, according to the present invention, an improvement of about 15% in the light-collecting intensity ratio over the conventional light source unit was obtained.

[Effect of the invention]

As described above, according to the light source unit of the present invention,
The focusing angle of the reflector is widened, and the convergence angle of the output beam to the optical transmission rod is within the range that does not increase the loss due to Fresnel reflection at the entrance surface of the optical transmission rod. Thus, the light beam can be efficiently incident on the optical transmission rod.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an explanatory diagram of a schematic configuration, and FIG. 2 is an explanatory diagram of a reflecting mirror portion. DESCRIPTION OF SYMBOLS 1... Bulb, 1a... Root 1b... Tip 2... Filament 3... Reflecting mirror 3a... Mounting 4... Light transmission rod 5... Cement F. Next focus, 2φ: Focusing angle 2θ: Outgoing beam convergence angle, d: Opening diameter h: Reflector depth WD: Working distance α: Beam divergence angle due to filament area

Claims (1)

(57) [Scope of request for utility model registration] 1. A light source unit having a spheroidal reflecting mirror and generating an outgoing beam to an optical transmission rod, wherein the converging angle of the reflecting mirror is 265 ° or more and the depth ratio is 0.65 or more. A light source unit, wherein the convergence angle of an output beam to a light transmission rod is 65 ° or less.