JPH03167503A - Reflecting mirror - Google Patents

Abstract

PURPOSE:To improve a color temperature without changing a color tone by constituting the boundary layer of two film groups having different reflected wavelength of an intermediate optical film having different film thickness from the film thickness of the optical film of either of the film groups. CONSTITUTION:The film group 10 consisting by laminating the optical films 11 whose film thickness is thin and the film group 20 consisting by laminating the optical film 21 whose film thickness is thick are formed on a base material 30 so that they are laminated through the intermediate optical film 40. Then, the film thickness of the film 40 is different from the respective optical film thickness of both film groups 10 and 20. Thus, a part of the yellow green component is eliminated from reflected light and the reflected light is adjusted by the natural color tone without lowering the color temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reflecting mirror that can improve color temperature without changing color tone.

[Conventional technology]

Reflecting mirrors are used in various fields, one of which is lighting. Since most lighting lamps use incandescent light bulbs such as mini halogen lamps, the following two requirements are generally required of the reflecting mirrors.

(1) Increasing the infrared rays (2) Increasing the color temperature (1) is to reduce heat radiation, and (2) is to correct the excessively strong red component of incandescent bulbs.

Increasing the color temperature can be easily achieved by slightly lowering the reflection characteristics of the reflector in the long wavelength range, that is, in the vicinity of red, to remove as much of the red color as possible from the reflected light. To give a specific example, a standard mini halogen lamp has a color temperature of around 2800°K, but when using it for lighting applications such as spotlights, a reflector with selective reflection characteristics is used. By removing some of the red color from the luminescent component, the color temperature can be raised to about 3050°K for use.

However, according to this method, a large amount of red color is removed from the light emitted by the incandescent light bulb, and as a result, the color balance of other colors becomes relatively strong, causing a change in the color balance. That is, among the other colors mentioned above, the color that has the greatest effect on the reflected light color is a yellow-green color. This is because yellow-green colors not only emit relatively large amounts of light from incandescent light bulbs, but also have a high relative luminous sensitivity of the eye. As mentioned above, when the red precept is removed to some extent and the precepts of other colors become relatively stronger, yellow-green colors will have the greatest effect among the other colors. As a result, the color of the light reflected from the reflecting mirror generally has a strong yellowish-green feel to the general public's perception.

Recently, it has become common to configure the mirror surface of a reflecting mirror with an optical multilayer film. One of the reasons for this is that, according to this method, it is easy to impart selectivity to the reflection characteristics of the mirror surface. Therefore, when constructing a mirror surface using this method, it may be possible to add some ingenuity to the layer structure of the optical multilayer film so that the mirror surface has selective reflection characteristics that will not cause the above problem. .

The inventor came up with the following idea in the process of making various improvements from this point of view.

Color temperature is determined based on the radiation of a perfect black body plotted on an x-y chromaticity diagram, so for substances that are not a perfect black body, it is not possible to specify the color by color temperature alone. Can not. In other words, different colors of light exist even with the same color temperature.Incandescent light bulbs use a tungsten filament, and their radiation curve is relatively close to that of a black body, and their radiation curve is completely black. It is located close to the body radiation curve. However, the radiation curve obtained by removing some of the red color and raising the color temperature shows a tendency for the y value to increase, moving further away from the complete black body radiation curve. As a result, when visually observed, it exhibits a yellowish-green color.

Therefore, in order to solve the above problem, it is sufficient to increase the color temperature without increasing the y value. This can be achieved by not only removing the red component when performing selective reflection, but also removing some of the yellow-green color that has the strongest effect among the other color components.

In order to obtain the necessary reflection bandwidth, reflective mirrors commonly used for lighting applications have a group of optical films that reflect relatively short wavelength bands and a group of optical films that reflect relatively long wavelength bands. The fI6 is made by stacking several layers of reflective optical films. In a typical membrane design, the bandwidths of both groups are seamlessly continuous to cover most of the visible range. For example, as shown in FIG. 4, a film group 10 formed by overlapping thin optical films 11 and a film group 20 formed by overlapping thick optical MJs 21 are directly overlapped. , is formed on the base material 30, thereby making it a two-wavelength reflecting mirror.

In this two-wavelength reflecting mirror, the yellow-green component reflection band is located exactly near the center of the total reflection band. The conventional color component removal method is to create a reflection valley by blanking the reflection band of the color component to be removed, so if this conventional method is used, the yellow-green component can be removed This can be achieved by separating the two wavelength reflection bands from each other and creating a reflection valley between the two bands. In other words, both reflection bands are made discontinuous to create a reflection valley. When the film groups 1020 of two wavelengths are separated from each other in this way, a region where the reflectance decreases is created at the break between the two groups. By setting this reduced reflection range to an appropriate wavelength range around yellow-green, the reflectance of yellow-green is reduced, making it possible to obtain a warm light color without a yellow-green appearance.

[Problem to be solved by the invention]

However, if this conventional method is used to remove the yellow-green color, the reflectance of the yellow-green color decreases, but at the same time, the color temperature also decreases. In other words, between the two wavelength film groups, This is because if a space is provided, the reflection band on the longer wavelength side shifts to the longer wavelength side, so that the reflection of red color increases.

In view of these circumstances, the present invention has been developed to improve the color temperature of a specular reflector made of an optical multi-band NB'A with a two-wavelength structure, and to emit reflected light that is not biased towards yellow-green. That's what you're trying to get.

[Means to solve the problem]

In order to solve the above problems, the reflecting mirror according to the present invention has the following features:
A reflecting mirror whose mirror surface is composed of optical multilayer films having different refractive indexes, the optical multilayer film comprising a film group consisting of a multilayer stack of thin optical films and a multilayer of thick optical films. It is characterized by comprising a film group formed by overlapping each other, and an intermediate optical film having a film thickness different from the film thickness of each of the optical films of both groups.

That is, the reflecting mirror according to the present invention, for example,
As shown in the figure, a film group lO formed by overlapping thin optical films l1 and a film group 20 formed by overlapping thick optical films 21 are overlapped with an intermediate optical film 40 interposed therebetween. The intermediate optical film 40 is formed on the base material 30 in such a manner that the film thickness of the intermediate optical film 40 is different from each of the optical film thicknesses of both film groups 10 and 20.

The intermediate optical film may be composed of multiple layers as long as the total thickness does not increase.

In this invention, the thickness of the intermediate optical film is set as follows: 0') to (
It is best to set the settings to suit the conditions of This is because if the film thickness does not meet the following conditions, the reflectance is unlikely to decrease or the spectral characteristics tend to be disturbed.

1. Optical film thickness of the group with smaller crotch thickness. 5 times ~ 2.
5 times.

(b) The film thickness is 0.3 to 0.3 times the optical film thickness of the smaller group.
7 times.

(c) 1.5 to 2 times the optical film thickness of the larger group.
5 times.

(Engineering) The optical film thickness of the group with the larger film thickness is 0. 3 times ~ 0
．． 7 times.

Note that when selecting these conditions, the intermediate optical film 4
When the film thickness of 0 is made 1.5 to 2.5 times the optical film thickness of each layer of the film group 10 with the smaller film thickness (condition (l)), the film thickness of the film group 20 with the larger film thickness It is necessary to make sure that the optical film thickness is not the same as each optical film thickness of each layer of the film group 20 with the larger film thickness. 3 times ~ 0. Needless to say, even when increasing the thickness by seven times (condition (4)), it is necessary to ensure that the optical film thickness does not become the same as the optical film thickness of each layer of the smaller film group 10. .

[For production]

In this invention, since the boundary layer between two film groups having different reflection wavelengths is constituted by an intermediate optical film having a film thickness different from that of the optical films of either group, a portion of this intermediate optical film is The reflectance in the vicinity of yellow-green is reduced, and part of the yellow-green component can be removed. That is, intermediate optics 1t! i
! The reflector shown in FIG. 4, which is not provided with 40, has the reflection characteristics as shown in FIG. It has a reflection characteristic that shows a specific decrease in reflectance. This removes some of the yellow-green component, thereby reducing the yellow-green appearance of the reflected light. Moreover, this intermediate optical film is extremely thin compared to the gap between the cuts provided in this part when using the conventional method, so inserting this intermediate optical film can cause the long wavelength range to be longer. No side shift occurs. Therefore, the reflection of the red component does not increase, and the color temperature does not decrease.

〔Example〕

Examples of the present invention will be described below.
The present invention is not limited to these examples.

Example 1 A reflecting mirror having a 15-layer structure was fabricated by a vacuum evaporation method for ordinary subsoto illumination. That is, as shown in Fig. 3, 70 mm was placed on a glass parabolic base l with a diameter of 70 mm.
Long wavelength side reflective film group of layer and intermediate optical film (boundary layer) of IN
A mirror surface 2 was formed by forming a group of 7 short-wavelength reflective films. At that time, a film thickness difference of 1.35 times is set between the two wavelength film groups, and the intermediate optical film thickness of the eighth layer, which is the boundary layer, is 0.5 times the film thickness of each layer on the long wavelength side. It was made to be 5 times more.

During the deposition, the thickness of the deposited film was controlled using a photoelectric film thickness meter. Since the film formed on the base material has a curved shape, strictly speaking,
Although the measurement results cannot be said to be accurate, each layer is approximately 176 nm on the long wavelength side, 88 nm on the boundary, and 130 nm on each layer on the short wavelength side.
It was nm.

For comparison, we also created a reflector in which the thickness of the boundary layer was the same as that on the longer wavelength side, that is, a reflector with a conventional two-wavelength structure.

When a 75W mini halogen lamp was attached to the reflector thus obtained and the reflection characteristics were evaluated, the color temperature of the reflector of the example was 3060'K, and the x-y chromaticity was X was 0.433 and y was 0.403. On the other hand,
The color temperature of the reflective mirror of the comparative example is 3050°K, and the x-y
The chromaticity was 0.437 for X and 0.410 for y.

In the visual evaluation, the examples had clearly less yellow-green appearance than the comparative examples, and had a natural color development. Of the 20 randomly selected reviewers, 17 rated it as favorable due to its natural feel.

Example 2 - Except that a film thickness difference of 1.38 times was provided between the two wavelength film groups, and the optical film thickness of the eighth layer, which was the boundary layer, was twice the film thickness of each layer on the long wavelength side. was produced in the same manner as in Example 1. The film thickness measurement results were approximately 180 nm for each layer on the long wavelength side, 360 nm for each layer on the boundary edge, and 130 nm for each layer on the short wavelength side.

On the other hand, when the same evaluation as in Example 1 was performed,
The color temperature is 3100°K, and the x-y chromaticity is when X is 0.
4 2 9, y was 0.400. Furthermore, in visual evaluation, the yellow-green appearance was clearly less than that of the comparative example used in Example 1, and the colors generally appeared natural and vivid. Of the 20 randomly selected evaluators, 16 rated it as favorable because of its natural feel.

〔Effect of the invention〕

Since the reflecting mirror according to the present invention has the above-mentioned configuration, it is possible to remove a portion of the yellow-green base from the reflected light without lowering the color temperature, and to adjust the color tone to a natural color tone. Further, since the reflection characteristics can be made slightly different by setting the film thickness ratio between the two wavelength film groups and the film thickness of the boundary layer, JaJ selection characteristics can be exhibited as required.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the invention, and FIG. 2 is a sectional view showing an embodiment of the invention.
A graph showing a comparison between the reflection characteristics of the reflector according to the present invention and the reflection characteristics of a conventional reflector, FIG. 3 is a half-sectional view of the reflector, and FIG. 4 is a cross-sectional view of the conventional reflector. be.

Claims (1)

[Claims] 1. A reflecting mirror whose mirror surface is composed of optical multilayer films having different refractive indexes, the optical multilayer film comprising a film group formed by stacking multiple thin optical films and a thick optical film. A reflecting mirror comprising a film group formed by stacking multiple layers, and an intermediate optical film having a film thickness different from the film thickness of each optical film in both groups.