JP2014164268A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device having properties suitable for outdoor use.SOLUTION: An optical device includes an exterior member (20) provided outside a light passage (15), and a reflective film (26) which is provided on at least a portion of a surface of the exterior member on a side opposite the light passage and whose average reflectance is greater for light of a wavelength of no less than 750 nm and less than 1700 nm than for light of a wavelength of no less than 400 nm and less than 650 nm and is greater for light of a wavelength of no less than 750 nm and less than 1700 nm than for light of a wavelength of no less than 2500 nm and less than 4000 nm.

Description

  The present invention relates to an optical device.

  An optical device such as a lens barrel provided in a camera may be used in an environment where a light beam including infrared light such as sunlight is irradiated. In the optical device according to the prior art, when used in an environment where a large amount of sunlight is irradiated, the temperature inside the optical device rises due to irradiation heat, and adversely affects the optical members and the like provided in the optical device. There is a problem.

  As a conventional technique for preventing the temperature rise of the optical device, for example, a technique is proposed in which a temperature-sensitive color changing layer that changes to white as the temperature rises is provided on the surface of the lens barrel (see Patent Document 1). However, in a shooting site where it is necessary to make equipment such as a lens barrel inconspicuous, inconvenience may occur due to the surface color of the lens barrel or camera changing to white.

JP 2007-49370 A

  On the other hand, when black (dark) is selected as the surface color, near infrared light is more easily absorbed than when white (light) is selected, and the temperature rise due to solar radiation tends to increase. is there.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical device that can suitably prevent temperature increase due to irradiation heat of sunlight even when the appearance is black.

In order to achieve the above object, an optical device according to the present invention comprises:
An exterior member (20) provided outside the light passage region (15);
Provided on at least a part of the surface opposite to the light passage region side of the exterior member, the average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm is higher than the average reflectance of light having a wavelength of 400 nm or more and less than 650 nm, and And a reflection film (26) having an average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm higher than an average reflectance of light having a wavelength of 2500 nm or more and less than 4000 nm.

  For example, the reflective film may contain ceramic powder.

  For example, the ceramic powder may contain aluminum oxide or zirconium oxide.

  For example, the reflective film is a coating film containing a pigment containing at least one element selected from Si, N, Al, Ti, Fe, Zn, Co, Mg, Ca, Sr, Ba, and Cu. There may be.

  For example, the reflective film may be a coating film containing a pigment or dye of an organic compound containing a perylene structure.

  Further, for example, the reflective film is disposed in a first coating film (22) having a light transmittance of 30% or more at a wavelength of 750 nm or more and less than 4000 nm, and a lower layer of the first coating film. You may have a 2nd coating film (24) whose solar reflectance is higher than a coating film.

For example, the first coating film may include a pigment or dye of an organic compound containing a perylene structure,
The second coating film may include a pigment containing at least one element selected from Si, N, Al, Ti, Fe, Zn, Co, Mg, Ca, Sr, Ba, and Cu.

  For example, the portion of the exterior member on which the reflective film is provided may be made of at least one selected from resin, metal, and carbon / resin composite material.

  In the above description, in order to explain the present invention in an easy-to-understand manner, the description is made in association with the reference numerals of the drawings showing the embodiments. However, the present invention is not limited to this. The configuration of the embodiment described later may be improved as appropriate, or at least a part of the configuration may be replaced with another component. Further, the configuration requirements that are not particularly limited with respect to the arrangement are not limited to the arrangement disclosed in the embodiment, and can be arranged at a position that can achieve the function.

FIG. 1 is an overall view of a lens barrel according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of a housing in the lens barrel shown in FIG. FIG. 3 is a graph showing the spectral reflectance and spectral emissivity of the reflective film shown in FIG. FIG. 4 is a partial cross-sectional view of a housing in a lens barrel according to the second embodiment of the present invention. FIG. 5 is an overall view of a lens hood according to the present invention. FIG. 6 is a perspective view of the camera body according to the present invention observed from the front side. FIG. 7 is a perspective view of the camera body according to the present invention observed from the back side.

First Embodiment FIG. 1 is an overall view of a lens barrel 10 according to a first embodiment. The lens barrel 10 is a telephoto interchangeable lens barrel that can be attached to and detached from the camera body of a so-called single-lens reflex camera. In the first embodiment, the lens barrel 10 is described as an example of the optical device. However, the embodiment is not limited to this, and the lens hood (see FIG. 5), the camera body (see FIGS. 6 and 7), Examples of other optical devices include a camera (a lens barrel and a camera integrated with each other). Further, the optical device is not limited to a still camera, a lens barrel of a still camera, or a camera body, and includes a video camera, a teleconverter, a telescope, binoculars, a monocular, and the like.

  The lens barrel 10 has a substantially cylindrical outer shape, and the outer periphery of the lens barrel 10 is constituted by a substantially cylindrical casing 12. The housing 12 includes a first portion 12a, a second portion 12b, and a third portion 12c having different outer diameters, and the first portion 12a and the second portion 12a are arranged from the subject side toward the imaging surface side. The portion 12b and the third portion 12c are arranged in this order. Each part 12a, 12b, 12c which comprises the housing | casing 12 has a bottomless cylindrical shape. The outer diameter of the housing 12 is gradually reduced from the subject side toward the imaging surface side, the outer diameter of the first portion 12a is the largest, and the outer diameter of the third portion 12c is the smallest.

  A light passage region 15 through which light can pass is formed in the direction along the central axis of the housing 12 on the center side of the cylinder constituting the housing 12. Further, an optical lens group 13 is provided in the light passage region 15 formed inside the housing 12. The optical lens group 13 emits light incident on the lens barrel 10 from the subject side to the imaging surface side (camera body side). Further, the lens barrel 10 according to the present embodiment can form an image of light incident from the subject side at a predetermined position after the light is emitted to the imaging surface side. In addition to the optical lens group, the housing 12 includes other optical members such as a diaphragm, and a drive unit and a control unit for changing the positions of these optical members.

  When the lens barrel 10 is used, a camera body (not shown) is attached to the imaging surface side of the housing 12. The camera body includes a recording medium that records an image of light formed by the optical lens group provided in the lens barrel 10. In addition, a lens hood may be attached to the subject-side end of the housing 12 in order to prevent unnecessary light from entering the light passage region 15 of the lens barrel 10.

  A zoom ring 16 is attached to the outside of the second portion 12 b of the housing 12. The zoom ring 16 is rotatable relative to the housing 12, and the user can change the focal length of the lens barrel 10 by rotating the zoom ring 16. A focus ring 17 is attached to the outside of the third portion 12 c of the housing 12. The focus ring 17 is an operation unit for changing the position of the optical lens group provided in the housing 12 and performing focus adjustment. Similar to the zoom ring 16, the focus ring 17 is rotatable relative to the housing 12, and the user can adjust the focus of the lens barrel 10 by rotating the focus ring 17.

  FIG. 2 is a cross-sectional view of the housing 12 shown in FIG. The housing 12 includes an exterior member 20 provided outside the light passage region 15 and a reflective film 26 provided on the surface of the exterior member 20 opposite to the light passage region 15 side. The exterior member 20 has a cylindrical shape like the housing 12 and functions as a structural material in the housing 12.

  The exterior member 20 has sufficient rigidity to support the optical lens group 13 and the like provided in the housing 12. The exterior member 20 is preferably made of, for example, a metal material containing Mg, Al, etc., a resin material such as polycarbonate, or a carbon / resin composite material, particularly from the viewpoint of securing rigidity while achieving weight reduction. It is not limited.

  The reflective film 26 is provided so as to cover the outer surface of the exterior member 20. In the lens barrel 10 shown in FIG. 1, the reflective film 26 is provided on the entire surface of each of the portions 12 a, 12 b, and 12 c constituting the housing 12, but the reflective film 26 is one of the outer surfaces of the exterior member 20. It may be provided only in the part. In that case, another film different from the reflective film 26 may be provided on another part of the outer surface where the reflective film 26 is not provided in order to protect the outer surface of the exterior member 20. .

  As shown in FIG. 2, the reflective film 26 is disposed in the first coating film 22 having a light transmittance of 30% or more at a wavelength of 750 nm or more and less than 4000 nm, and the lower layer of the first coating film 22. A second coating film 24 having higher solar reflectance (JIS K5602: 2008) than the first coating film 22.

  The first coating film 22 has a lower solar reflectance than the second coating film 24, and is preferably dark (black). The first coating film 22 includes an infrared light transmitting color material 30 in order to increase the infrared light transmittance. Although it does not specifically limit as the infrared light transmissive color material 30 contained in the 1st coating film 22, The pigment or dye of the organic compound containing a perylene structure is mentioned. In the present embodiment, the first coating film 22 is disposed on the outermost surface of the housing 12, but the configuration of the housing 12 is not limited thereto, and for example, on the outer surface of the first coating film 22, Further, a transparent film may be formed.

The first coating film 22 includes a mid-infrared / far-infrared absorbing material 34 that absorbs mid-infrared light and far-infrared light other than near-infrared light in infrared light. Although it does not specifically limit as the mid-infrared / far-infrared absorbing material 34 included in the first coating film 22, for example, those containing ceramic powder are preferable, and ceramic powder containing aluminum oxide or zirconium oxide is particularly preferable. The ceramic powder containing aluminum oxide or zirconium oxide can enhance absorption of wavelengths in the mid-infrared and far-infrared regions in a coating film containing the same.

  The second coating film 24 is sandwiched between the first coating film 22 and the exterior member 20, and the outer surface of the second coating film 24 is covered with the second coating film 24. The second coating film 24 has a higher solar reflectance than the first coating film 22, and is preferably light (white). The second coating film 24 preferably contains an infrared light reflecting color material 32 that enhances the reflection of infrared light. Although it does not specifically limit as the infrared light reflection color material 32 contained in the 2nd coating film 24, For example, from Si, N, Al, Ti, Fe, Zn, Co, Mg, Ca, Sr, Ba, Cu A pigment containing at least one selected element is preferably used.

  The first coating film 22 and the second coating film 24 of the reflective film 26 as shown in FIG. 2 are formed by coating or the like. For example, the reflective film 26 is applied to the outer surface of the exterior member 20 by applying a coating material that becomes the second coating film 24 after drying to form the second coating film 24, and then on the outer surface of the second coating film 24. It can form by apply | coating the coating material used as the 1st coating film 22 after drying.

  FIG. 3A shows the spectral reflectance of the reflective film 26 shown in FIG. 2 together with the spectral reflectances of the coating film 80 and the coating film 82 which are reference examples. The coating film 80 is a general black coating film using a pigment such as carbon black, and has an overall low reflectance from the visible light region to the far infrared region. When the coating film 80 is formed on the outer surface of the exterior member 20, the coating film 80 absorbs sunlight including infrared light, and thus the temperature rise of the optical device due to solar radiation tends to increase.

  On the other hand, the coating film 82 is the same as the reflecting film 26 shown in FIG. 2 except that the first coating film has no mid-infrared / far-infrared absorbing material. The coating film 82 appears to be black with low visible light reflectance due to the action of the infrared light transmitting colorant 30 contained in the first coating film and the second coating film 24 in the lower layer with increased infrared light reflectance. Nevertheless, since the reflectance of infrared light is high, an increase in the temperature of the optical device due to solar radiation can be suppressed as compared with the coating film 80.

However, the coating film 82 has a higher reflectance in the near infrared wavelength region and does not have an absorbent in the middle infrared wavelength region to the far infrared wavelength region, and has a mid infrared wavelength region to a far infrared wavelength. If the reflectance of the region remains high, the temperature rise suppression effect becomes smaller as the temperature (environmental temperature) rises than when the temperature is low. This is because the influence of radiation (thermal radiation, that is, electromagnetic waves) emitted from the device surface to the outside appears.
The mechanism by which the ability to suppress temperature rise due to solar radiation is reduced due to the rise in temperature is as follows. That is, the coating film 80 has a large contribution of thermal radiation, and when the temperature rises, it becomes difficult to raise the temperature slightly due to the effect of thermal radiation, whereas the coating film 82 has a small contribution of thermal radiation and the temperature rises. However, it is not difficult to raise the temperature (almost unchanged).
In this situation, that is, when the temperature rises, the emissivity of the device surface (that is, the coating surface) may be increased in order to prevent the temperature rise suppression effect from decreasing. However, the reflectance and the emissivity are in a trade-off relationship, and 1−reflectance = emissivity.
As a result of the examination considering the above circumstances, the coating film has a characteristic that it reflects solar radiation, that is, only the reflectance in the near-infrared region of the sunlight spectrum needs to be increased. It was.
For this purpose, as the reflection film 26, a ceramic (sintered) powder, which is a material that absorbs mid-infrared and far-infrared light, particularly a metal oxide such as aluminum oxide or zirconium oxide is added, It is effective to use a film that absorbs mid-infrared and far-infrared wavelengths exceeding 2300 nm.
The reason why the addition of the mid-infrared and far-infrared absorbers is effective is as follows. As sunlight passes through the atmosphere, there is almost no component of light having a wavelength exceeding 2300 nm, which can be ignored. Therefore, even if light having a wavelength exceeding 2300 nm is absorbed, the reflection of sunlight (sunlight) is not affected. That is, the emissivity can be increased without affecting the characteristic of reflecting sunlight (sunlight).

  As shown in FIG. 3A, the reflective film 26 has a higher average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm than that of light having a wavelength of 400 nm or more and less than 650 nm, and a wavelength of 2500 nm or more and less than 4000 nm. The average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm is higher than the average reflectance of light. That is, since the first coating film 22 of the reflective film 26 includes the mid-infrared / far-infrared absorbing material 34, the reflective film 26 does not include the mid-infrared / far-infrared absorbing material 34. Compared to the above, the reflectance of light in the mid-infrared and far-infrared regions is low.

  As is clear from FIG. 3B showing the spectral emissivity of the reflective film 26, the reflective film 26 has a high average emissivity at a wavelength of 400 nm or more and less than 650 nm, and an average emissivity at a wavelength of 750 nm or more and less than 1700 nm. The average emissivity is low and the wavelength is 2500 nm or more and less than 4000 nm, and the heat radiation is higher than that of the coating film 82.

  Thus, the reflective film 26 has a high reflectance of near-infrared light, and has a low reflectance (that is, a high emissivity) in a wavelength region other than the near-infrared region. The lens barrel 10 having the exterior member 20 (see FIG. 2) on which such a reflective film 26 is formed can suitably prevent a temperature rise due to sunlight irradiation heat even if the appearance is black. it can. In particular, since the reflective film 26 includes the mid-infrared / far-infrared absorbing material 34, the emissivity in the mid- / far-infrared region is high, and it has good thermal radiation, thereby preventing the temperature rise due to solar radiation. Even if the environmental temperature (outside air temperature) is high, the performance will not deteriorate.

  The reflective film 26 includes a first coating film 22 including the infrared light transmitting color material 30, and a second coating film 24 disposed below the first coating film 22 and including the infrared light reflecting color material 32. Therefore, even if the appearance is black, it has a high reflectance with respect to near-infrared light, and it is possible to suitably prevent a temperature increase due to sunlight irradiation heat.

Second Embodiment FIG. 4 is a cross-sectional view of a housing 70 in a lens barrel according to a second embodiment. The housing 70 is the same as the housing 12 (see FIG. 2) according to the first embodiment, except that the reflective film 76 provided on the outer surface of the exterior member 20 is different. In the reflective film 76 of the housing 70, the mid-infrared / far-infrared absorbing material 34 is included in the lower second coating film 74 instead of the upper first coating film 72. Such a reflective film 76 also exhibits the same spectral reflectance (see FIG. 3A) as that of the reflective film 26 described in the first embodiment, and has the same effect as the reflective film 26. The mid-infrared / far-infrared absorbing material 34 may be included in both the first coating film and the second coating film.

Third Embodiment FIG. 5 is a schematic perspective view showing a lens hood 40 according to a third embodiment. The lens hood 40 is used by being attached to the subject side end of the lens barrel 10 shown in FIG. 1, and prevents unnecessary light from entering the light passage region 15 of the lens barrel 10. The lens hood 40 has a housing 42 provided outside the light passage region 45, and the housing 42 has the same structure as the housing 12 (see FIG. 2) according to the first embodiment.

  As described above, the exterior member 20 provided with the reflective film 26 as shown in FIG. 2 is not limited to the one included in the case 12 of the lens barrel 10, and the case of the lens hood 40 as shown in FIG. An exterior member included in the body 42 may be used. The housing 42 of the lens hood 40 according to the third embodiment also has the same effects as the housing 12 of the lens barrel 10 according to the first embodiment.

Fourth Embodiment FIG. 6 is a perspective view from the front side of a camera body 50 according to the fourth embodiment, and FIG. 7 is a perspective view from the back side of the camera body 50. The camera body 50 has a lens mount 57 for connecting an end portion on the imaging surface side of the lens barrel 10 shown in FIG. 1 and is used in combination with the lens barrel 10. Inside the camera body 50, a light passage region 55 is formed which extends from the opening (see FIG. 6) of the lens mount 57 to the viewfinder eyepiece 69 (see FIG. 7).

  The camera body 50 includes a housing 52 that is disposed outside the light passage region 55. The casing 52 has the reflective film 26 as shown in FIG. 2 only on the upper surface 52a of the casing which is indicated by hatching in FIGS. The housing upper surface 52a is more easily irradiated with sunlight than other portions, and is disposed around the release switch 59 (see FIG. 6) and the viewfinder eyepiece 69 (see FIG. 7). It is also a part where the operator of the main body 50 can easily touch.

  Similar to the lens barrel 10 according to the first embodiment, such a camera body 50 can suitably prevent a temperature rise due to sunlight irradiation heat even if the appearance is black. In addition, since the camera body 50 includes the reflective film 26 disposed on the housing upper surface 52a that is easily touched by the operator, the camera body 50 can effectively suppress the temperature rise of the housing upper surface 52a. The main body 50 can be operated comfortably. In the case 52 of the camera body 50, the back surface portion 52b (disposed around the display panel 67), the bottom surface portion 52c, and the like, which are relatively difficult to irradiate with sunlight, are made of the coating film 80 shown in FIG. By forming such a normal black coating film, it is also possible to increase the heat radiation.

DESCRIPTION OF SYMBOLS 10 ... Lens barrel 12, 42, 52 ... Housing 13 ... Optical lens group 15, 45, 55 ... Light passage area 16 ... Zoom ring 17 ... Focus ring 20 ... Exterior member 22, 72 ... 1st coating film 24, 74 ... 2nd coating film 26, 76 ... Reflective film 30 ... Infrared light transmitting color material 32 ... Infrared light reflecting color material 34 ... Middle infrared / far infrared absorbing material 40 ... Lens hood 52a ... Upper surface of housing

Claims (8)

An exterior member provided outside the light passage region;
Provided on at least a part of the surface opposite to the light passage region side of the exterior member, the average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm is higher than the average reflectance of light having a wavelength of 400 nm or more and less than 650 nm, and An optical device comprising: a reflective film having an average reflectance of light having a wavelength of 750 nm or more and less than 1700 nm higher than an average reflectance of light having a wavelength of 2500 nm or more and less than 4000 nm. The optical device according to claim 1,
The optical device, wherein the reflective film contains ceramic powder. An optical device according to claim 2, comprising:
The optical device, wherein the ceramic powder contains aluminum oxide or zirconium oxide. An optical device according to any one of claims 1 to 3, wherein
The reflective film is a coating film containing a pigment containing at least one element selected from Si, N, Al, Ti, Fe, Zn, Co, Mg, Ca, Sr, Ba, and Cu. An optical device. An optical device according to any one of claims 1 to 4, wherein
The optical device, wherein the reflective film is a coating film containing a pigment or dye of an organic compound having a perylene structure. An optical device according to any one of claims 1 to 5, wherein
The reflection film is disposed in a first coating film having a light transmittance of 30% or more at a wavelength of 750 nm or more and less than 4000 nm, and a lower layer of the first coating film, and has a solar reflectance from the first coating film. An optical device having a high second coating film. The optical device according to claim 6, comprising:
The first coating film includes a pigment or dye of an organic compound containing a perylene structure,
The second coating film includes a pigment containing at least one element selected from Si, N, Al, Ti, Fe, Zn, Co, Mg, Ca, Sr, Ba, and Cu. Optical device. An optical device according to any one of claims 1 to 7,
The optical device is characterized in that the portion of the exterior member on which the reflective film is provided is made of at least one selected from resin, metal, and carbon / resin composite material.

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