JP2005266537A - Infrared transmission filter and infrared projector including the infrared transmission filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that leaked light is colored and mistaken for the lighting of a display lamp when it is seen from a vehicle, but it is impossible to prevent the leakage of visible light in an infrared transmission filter for an infrared projector. <P>SOLUTION: The infrared transmission filter 1 selecting infrared out of luminescent color from an incandescent lamp is constituted by successively forming a 1st laminated film group 2 having absorption characteristic in a visible light region and adjusting the quantity of the leaked light, a 2nd laminated film group 3 controlling chromaticity on the leaked light by performing the wavelength control of the leaked light in the visible light region, and a 3rd laminated film group 4 performing the wavelength control that infrared light is transmitted from a light source side, and is set so that the leaked light transmitted through the 1st and the 2nd laminated film groups is white light within a specified chromaticity range. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  Since the present invention has a situation in which it is forced to travel with a light distribution even at night, the visibility to a distant place is insufficient, and there is a possibility of causing a dangerous situation such as delay in checking an obstacle. So-called night vision, it is far away by illuminating the front with an infrared projector that does not cause illusion to the driver of the oncoming vehicle, and displaying an image taken with an imaging tube sensitive to infrared rays The present invention relates to an infrared projector used for securing a field of view, and an infrared transmission filter provided in the infrared projector for cutting visible light.

As a conventional infrared filter of this type, silicon (Si) as a high refractive index film and silicon dioxide (SiO ₂ ) as a low refractive index film are alternately laminated, and more than 80% in the infrared region of 900 to 1500 nm. An infrared transmission filter having a transmittance of 0.1% or less in a visible light region of 400 to 800 nm is known.
JP 2000-314807 A

  Here, downsizing is carried out for mounting on a vehicle, and thus, in an infrared projector in which the distance between a light source such as a halogen bulb and an infrared transmission filter is reduced, the transmittance for visible light is 0.001%. Even when it is below (the amount of light is only 1/100 of the conventional example), the result is that visible light leaks and the presence of the infrared projector is detected by the driver of the oncoming vehicle.

  Thus, for example, when the leakage light is red, there is a sufficient risk of being misidentified as a stoplight, taillight, etc. provided behind the vehicle. Further, there is a risk of misidentification as a vehicle width lamp, a parking lamp, and the like, and there is also a risk of misunderstanding that it is other than the vehicle if the color is other than that.

  Therefore, when installing an active night vision that requires an infrared projector in a vehicle, the chromaticity of the visible light leaking from the infrared projector is designated as white so as not to cause unnecessary misidentification. Was decided. However, in the configuration of the conventional infrared transmission filter described above, there is no technique that can control even the chromaticity of the visible light that leaks out, and thus the required chromaticity can be obtained without a control method. There is no problem.

  The present invention provides, as a specific means for solving the above-described conventional problems, an infrared transmission filter that mainly selects infrared rays from light emitted from an incandescent bulb, and the infrared transmission filter is a high refractive index film. And a plurality of pairs of low refractive index films are laminated, and the laminated film group has an absorption characteristic in the visible light region and adjusts the amount of leakage light. A wavelength control for the leakage light in the visible light region, a second lamination film group for controlling the chromaticity for the leakage light, and a wavelength control for transmitting infrared rays. The three laminated film groups are sequentially formed from the light source side, and the leakage light transmitted through the first laminated film group and the second laminated film group is white light within a specified chromaticity range. Infrared transmission characterized by It solves the problem by providing a filter.

  According to the present invention, in forming an infrared transmission filter by laminating a high refractive index film and a low refractive index film, a first laminated film group for controlling the transmittance of the visible light portion, and the first laminated film group The visible light transmitted by is converted into a predetermined white light by passing through the second laminated film group having a wavelength selection system with respect to the visible light, and infrared rays in a desired wavelength range are converted into the third wavelength. In addition to satisfying the performance as an infrared projector, the leaked light that cannot be completely eliminated is specified white, and it is mistaken for other lamps. It avoids and solves the problem.

  Below, this invention is demonstrated in detail based on embodiment shown in a figure. FIG. 1 schematically shows the configuration of an infrared transmission filter 1 according to the present invention. This infrared transmission filter 1 is formed on a transparent substrate 5 such as a glass substrate. On the top, a thin film 2A formed with a high refractive index member and a thin film 2B formed with a low refractive index member, each paired with a predetermined film thickness, are further formed into a multilayer. The laminated first laminated film group 2 is formed.

  Further, on the upper surface of the first laminated film group 2, a predetermined number of thin films 3A made of a high refractive member and thin films 3B made of a low refractive member, each having a predetermined film thickness, are alternately laminated. In addition, a second laminated film group 3 is formed, and further, above the second laminated film group 3, a thin film 4A made of a high refractive member and a thin film 4B made of a low refractive member are similarly formed. A third laminated film group 4 is provided. In the present invention, each of the laminated film groups 2, 3, and 4 or a combination thereof performs a predetermined action.

  Hereinafter, as described above, the structure of each laminated film group 2, 3, 4 when the three laminated film groups 2, 3, 4 are provided according to the present invention, and the operation and effect when they are combined. Will be described. First, in the infrared transmission filter 1 of the present invention, the first laminated film group 2 is provided on the substrate 5 side and basically transmits infrared rays and blocks visible light.

The first laminated film group 2 includes, for example, a thin film 2A of a high refractive index member such as Si (refractive index 4.2) and a thin film 2B of a low refractive index member such as SiO ₂ (refractive index 1.46) alternately. The thin films 2A and 2B are appropriately laminated, for example, and have a predetermined film thickness such as a quarter wavelength with respect to the wavelength of light intended for shielding.

  The characteristics of the first laminated film group 2 are mainly formed for the purpose of attenuating visible light, and transmit infrared light without causing much loss. However, for the visible light, attenuation of the amount of light is considered as a first object, and the color of visible light that is transmitted is not so much considered.

In the present invention, the thin film 3A of a high refractive index member such as TiO ₂ (refractive index 2.28), for example, and SiO ₂ (refractive index 1.46) are stacked on the first laminated film group 2 in the same manner. The second laminated film group 3 in which the thin film 3B of the low refractive index member is laminated is formed. And the main function of this 2nd laminated film group 3 is adjustment of the color tone of the visible light which permeate | transmitted the above-mentioned 1st laminated film group 2, and the 1st laminated film group 2 was also demonstrated above. Since the main purpose is to attenuate visible light in this way, the leaked light is colored according to the characteristics of the first laminated film group 2.

  Therefore, the second laminated film group 3 is designed with reference to the component values of red light (R), green light (G), and blue light (B) of the light transmitted through the first laminated film group 2. By setting the value of the wavelength value λ2, the ratio of red light (R), green light (G), and blue light (B) when passing through the second laminated film group 3 is changed. The color of the light after passing through the laminated film group 2 and the second laminated film group 3 is adjusted so as to be within a specified white range.

  As described above, when only the adjustment of the design wavelength value λ2 of the second laminated film group 3 does not give the leaking light a color that falls within the prescribed white light range, the first laminated film group 2 The design wavelength value λ1 may also be changed within a range that does not adversely affect the amount of visible light leakage, and the ratio of the three primary colors of R, G, and B may be changed so that more white light can be obtained. is there.

  The third laminated film group 4 is provided so as to cover the outer surface of the second laminated film group 3, and has a high refractive index member made of the same material as the second laminated film group 3, and a low It is formed using a refractive index member. However, the design wavelength value λ3 is set to a longer wavelength side so as to transmit and radiate only the infrared range defined as night vision.

  The above is the configuration and operation of the infrared transmission filter 1 according to the present invention. In the past, the infrared transmission filter was formed only by the third laminated film group 4 of the present invention, focusing only on the necessary band. On the other hand, in the present invention, by adding the first and second laminated film groups 2 and 3, a vehicle for other purposes is assumed to generate white light against visible leakage light that cannot be completely eliminated. To avoid being misidentified as a lighting fixture,

FIG. 2 shows an example of the configuration of the infrared transmission filter 1 according to the present invention as Example 1. Layer numbers 1 to 6 in the figure correspond to the first laminated film group 1. In Example 1, the amount of leakage light in the visible light region is adjusted by the lamination of Si / SiO ₂ . Further, the layer number 7 to the layer number 12 correspond to the second laminated film group 3 and are laminated with TiO ₂ / SiO ₂ , and the wavelength control of the leaked light in the visible light region transmitted through the first laminated film group 1 is performed. The chromaticity of the leaked light is controlled so as to be within a prescribed white light region. The layer number 13 to the layer number 28 correspond to the third laminated film group 4, and infrared rays for night vision are generated from, for example, a light beam of a halogen lamp by the lamination of TiO ₂ / SiO ₂ .

  The graphs shown in FIGS. 3 and 4 show the wavelength characteristics of the infrared transmission filter 1 shown in FIG. 2, and FIG. 3 shows the overall wavelength characteristics τa1 and is required as a projector for night vision. It can be understood that the characteristic of efficiently transmitting a wavelength longer than 800 nm is obtained.

  FIG. 4 is an enlarged view of the portion of visible light τb1 having the wavelength characteristics shown in FIG. The light chromaticity is x = 0.338 and y = 0.338, which is substantially white light.

  FIG. 5 shows an example of the configuration of the infrared transmission filter 1 according to the present invention as Example 2. In Example 2, the layer number 1 to the layer number 9 in FIG. The laminated film group 1 is formed. The portion corresponding to the second laminated film group 3 and the portion corresponding to the third laminated film group 4 are the same as those in the first embodiment in terms of the number of layers and the film thickness.

  Thus, by increasing the number of layers of the first laminated film group 1 for controlling the transmittance for visible light, as shown in FIG. 6, 800 nm required as a projector for night vision in the entire wavelength τa 2. Without significantly affecting the characteristics for longer wavelengths, the transmittance in the range of visible light τb2 of about 400 to 700 nm (purple to red) is dramatically reduced to about 1% or less as shown in FIG. It becomes possible to make it. The light chromaticity of the leaking light is also x = 0.338 and y = 0.332, which is substantially white light.

  FIG. 8 shows an example of the configuration of the infrared transmission filter 1 according to the present invention as Example 3. This Example 3 is basically the first laminate of the first example. The film thickness of the first layer formed of Si of the film group 1 is changed from 1/8 · λ1 to 1/16 · λ1. As a result, substantially no change occurs in the transmittance in the infrared light region in the entire wavelength τa3 as shown in FIG. 9, but in the visible light region τb3 as shown in FIG. Has almost doubled. However, the light chromaticity of the leaked light is x = 0.212, y = 0.335, and it is kept substantially white light.

  FIG. 11 shows an example of the configuration of the infrared transmission filter 1 according to the present invention as a fourth embodiment. This fourth embodiment is basically the first laminate of the first embodiment. The film thickness of the first layer formed of Si of the film group 1 is changed from 1/8 · λ1 to 3/16 · λ1. As a result, as shown in FIG. 12, there is no significant change in the transmittance in the infrared region of the entire wavelength τa4. It is about half or less than that of the product. The light chromaticity of the leaked light is x = 0.320, y = 0.317, which is substantially white light.

  The infrared transmission filter 1 configured as described above includes, for example, a reflecting mirror 11 formed as a rotating paraboloid, a halogen lamp 12 in which a filament 12a is disposed at the focal point of the reflecting mirror 11, and the reflecting mirror. 11 and a lens 13 that covers the front of the halogen lamp 12, is installed in the optical path of the lamp, shields visible light from the halogen lamp 12, and uses the lamp as an infrared projector 10. Become.

  FIG. 14 shows an infrared projector 10 shown as a fifth embodiment. In the fifth embodiment, the infrared transmission filter 1 is provided integrally with the lens 13. By doing so, both the direct light from the halogen lamp 12 and the reflected light are transmitted through the infrared transmission filter 1 (that is, the lens 13) and radiated to the outside. Satisfies performance.

  Further, in the method in which the infrared transmission filter 1 is integrated with the lens 13 in this way, it is easy to provide a distance between the filament 12a that is a light source and the infrared transmission filter 1, so that leakage light is also present at one location of the infrared transmission filter 1. Without concentrating on the surface, it is dispersed over the entire surface, the leak strength is made uniform, and the appearance is improved.

  FIG. 15 shows an infrared projector 10 shown as a sixth embodiment. In this sixth embodiment, the infrared transmission filter 1 is integrated with the outer diameter of the bulb 12 b of the halogen lamp 12. In this way, it is not necessary to prepare special ones for the reflecting mirror 11 and the lens 13, and only a halogen lamp 12 provided with the infrared transmission filter 1 is attached, and a general lamp can be used as the infrared projector 10. Can be used.

  FIG. 16 shows an infrared projector 10 shown as Example 7. In Example 7, the infrared transmission filter 1 is provided so as to be detachable with respect to the halogen lamp 12, for example, the infrared transmission filter 1 is moved forward. When this is done, direct light from the halogen lamp 12 reaches the reflecting mirror 11, white light is emitted from the lens 13, and when the infrared transmission filter 1 is moved backward, the light transmitted through the infrared transmission filter 1 is reflected. It reaches the mirror 11, and infrared light is emitted from the lens 13.

  By doing so, for example, a lamp that projects visible light, such as a headlight and fog light, and an infrared projector 10 for night vision can be switched back and used as necessary, and the use as a lamp is expanded. Can be achieved.

It is explanatory drawing which shows schematically the example of a structure of the infrared rays transmission filter which concerns on this invention. It is a block diagram which shows the structure which concerns on Example 1 of the infrared rays transmission filter which concerns on this invention. 3 is a graph showing all wavelength characteristics of an infrared transmission filter according to Example 1. FIG. 4 is an enlarged graph showing a state of leakage light generation in the visible light region of the infrared transmission filter according to the first embodiment. It is a block diagram which shows the structure which concerns on Example 2 of the infrared rays transmission filter which concerns on this invention. 6 is a graph showing the entire wavelength characteristics of an infrared transmission filter according to Example 2. It is a graph which expands and shows the generation | occurrence | production state of the leakage light in the visible light area | region of the infrared rays transmission filter which concerns on Example 2. FIG. It is a block diagram which shows the structure which concerns on Example 3 of the infrared rays transmission filter which concerns on this invention. 6 is a graph showing the entire wavelength characteristics of an infrared transmission filter according to Example 3. It is a graph which expands and shows the state of generation of leakage light in the visible light region of the infrared transmission filter according to Example 3. It is a block diagram which shows the structure which concerns on Example 4 of the infrared rays transmission filter which concerns on this invention. 6 is a graph showing all wavelength characteristics of an infrared transmission filter according to Example 4; It is a graph which expands and shows the generation | occurrence | production state of the leak light in the visible light area | region of the infrared rays transmission filter which concerns on Example 4. FIG. It is a schematic sectional drawing which shows the structure of Example 5 of the infrared projector which concerns on this invention. It is a schematic sectional drawing which shows the structure of Example 6 of the infrared projector which concerns on this invention. It is a schematic sectional drawing which shows the structure of Example 7 of the infrared projector which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Infrared transmission filter 2 ... 1st laminated film group 2A ... The thin film formed by the high refractive index member 2B ... The thin film formed by the low refractive index member 3 ... 2nd laminated film group 3A ... By the high refractive index member Formed thin film 3B ... Thin film formed by low refractive index member 4 ... Third laminated film group 4A ... Thin film formed by high refractive index member 4B ... Thin film formed by low refractive index member 5 ... Substrate 10 ... Infrared projector 11 ... reflecting mirror 12 ... halogen lamp 12a ... filament 12b ... bulb 13 ... lens

Claims (7)

  An infrared transmission filter that mainly selects infrared rays from light emitted from an incandescent light bulb, and the infrared transmission filter includes three types of laminated films in which a plurality of pairs of a high refractive index film and a low refractive index film are laminated. The laminated film group has a first laminated film group that has absorption characteristics in the visible light region and adjusts the amount of leaked light, and wavelength control for the leaked light in the visible light region And a second laminated film group that controls the chromaticity with respect to the leaked light and a third laminated film group that performs wavelength control for transmitting infrared light are sequentially formed from the light source side. The infrared transmission filter, wherein the leakage light transmitted through the multilayer film group and the second multilayer film group is white light within a specified chromaticity range.   The film material on the high refractive index film side for forming the first laminated film group having absorption characteristics in the visible light region is any one of metal Si, amorphous Si, poly-Si, and Ge The infrared transmission filter according to claim 1. The film material on the high refractive index film side for forming the second laminated film group and the third laminated film group is any one of TiO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , and Al ₂ O ₃ . The infrared transmission filter according to claim 1 or 2, wherein   The first layer of the first laminated film group adjusts the leakage light transmittance by changing the film thickness within a range of 1 / 64λ to λ with respect to the film design wavelength λ. The infrared transmission filter according to any one of claims 1 to 3, wherein the infrared transmission filter is characterized. 5. The infrared transmission filter according to claim 1, wherein the low refractive index film of the first to third laminated film groups is any one of SiO ₂ and MgF ₂ . The stack of Si / SiO ₂ and TiO ₂ / SiO ₂ in the first stacked group and the second stacked film group can freely control the leakage light transmittance and the color tone of the leakage light (wavelength range of 380 nm to 780 nm). The infrared transmission filter according to any one of claims 1 to 5, wherein the adjustment is performed to achieve a desired chromaticity. An infrared projector comprising the infrared transmission filter according to any one of claims 1 to 6.

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