JP2008233237A - Optical member, imaging apparatus, and lens barrel for vehicle-mounted camera - Google Patents

Abstract

An optical member, an image pickup apparatus, and an in-vehicle camera barrel that can suppress dew condensation generated on a lens surface are provided.
A heat insulating ring is disposed between an outer peripheral surface of a lens and an inner peripheral surface of a lens barrel. Further, a heat insulating ring 14 is disposed between the outer peripheral surface of the lens 12 and the inner peripheral surface of the lens barrel 19. Even when the outside air temperature drops and the temperature of the lens barrel 19 facing the outside air drops, a rapid temperature change of the lenses 11 and 12 can be suppressed, and the lens barrel 19 and the lenses 11 and 12 are surrounded. The water vapor in the air in the region is mainly condensed on the inner surface of the lens barrel 19 excluding the heat insulating rings 13 and 14, and the condensation occurring on the surfaces of the lenses 11 and 12 can be suppressed.
[Selection] Figure 2

Description

  The present invention relates to an optical member that can suppress the occurrence of dew condensation on the surface of a lens housed in a lens barrel, an imaging device including the optical member, and a lens barrel for an in-vehicle camera.

  An imaging device (on-vehicle camera) mounted on a vehicle such as an automobile is composed of an optical member (lens unit, lens module) containing a lens in a lens barrel, an imaging device, an image processing unit, etc., and is exposed to wind and rain. A waterproof structure is adopted to improve environmental resistance. However, water vapor in the air condenses on the lens barrel surface, the lens surface inside the lens barrel, and the like due to the temperature difference of the outside air temperature. Condensation that occurs on the lens surface that touches the outside air, the outer peripheral surface of the lens barrel, and the like can be wiped off from the outside, but the condensation that occurs on the lens surface inside the lens barrel cannot be easily wiped off.

  Since condensation on the lens surface degrades the optical performance of the imaging device, a method for suppressing condensation on the lens surface has been proposed. For example, by forming thin parts that are thinner than the exposed part that exposes the viewfinder on both sides of the waterproof case that houses the lens-fitted film unit, the temperature of the inner wall of the thin part is lowered before the other parts. In addition, a waterproof camera that suppresses condensation that occurs in the exposed portion by condensing condensation on the thin-walled portion has been proposed (see Patent Document 1).

Further, in order to increase the surface area of the inner surface of the spacer ring interposed between the lenses housed in the lens barrel, by providing a moisture adhesion surface having a concave curved surface shape in the thickness direction on the inner surface of the spacer ring. A lens device for preventing condensation has been proposed (see Patent Document 2).
JP 2000-194048 A Japanese Patent Laid-Open No. 10-148745

  However, as in the example of Patent Document 1, when an imaging device in which a thin part is formed in a lens barrel is mounted on a vehicle, the thin part of the lens barrel is deformed due to vibration or impact generated during the traveling of the vehicle. There is a high possibility that problems such as degradation of optical characteristics of the apparatus or failure of the imaging apparatus will occur.

  In the example of Patent Document 2, since the lens barrel is made of a metal having high thermal conductivity, the temperature change of the outside air temperature is easily transmitted to the lens via the lens barrel, and is generated on the lens surface. Condensation cannot be sufficiently suppressed. In particular, in the case of a far-infrared imaging device, a lens (for example, ZnS, Ge) that transmits far-infrared light has a higher thermal conductivity than glass used for visible light, and thus the occurrence of condensation is more prominent. Become. In the case where the vehicle is equipped for the purpose of safe driving like an in-vehicle imaging device, it has been an important issue to suppress the dew condensation generated on the lens surface.

  The present invention has been made in view of such circumstances, and is generated on the lens surface by providing a resin heat insulating member between the lens outer peripheral surface and the lens barrel inner peripheral surface housed in the lens barrel. An object of the present invention is to provide an optical member that can suppress dew condensation, an imaging device including the optical member, and an in-vehicle camera barrel.

  An optical member according to a first aspect of the present invention is an optical member in which a lens is housed in a lens barrel, and is characterized by including a resin heat insulating member between the lens outer peripheral surface and the lens barrel inner peripheral surface.

  An optical member according to a second invention is characterized in that, in the first invention, the heat insulating member is a heat insulating film formed on the inner peripheral surface of the lens barrel in contact with the outer peripheral surface of the lens.

  An optical member according to a third invention is characterized in that, in the first invention, the heat insulating member is a heat insulating film formed on the outer peripheral surface of the lens.

  The optical member according to a fourth invention is characterized in that, in any one of the first invention to the third invention, the heat conductivity of the heat insulating member is smaller than the heat conductivity of the lens barrel.

  An optical member according to a fifth aspect of the invention is an optical member in which a lens is housed in a lens barrel, wherein an air layer is formed between the inner peripheral surface of the lens barrel and the outer peripheral surface of the lens.

  An optical member according to a sixth aspect of the present invention is the optical member according to any one of the first to fifth aspects, wherein the lens is configured to transmit far infrared light.

  An image pickup apparatus according to a seventh aspect includes the optical member according to any one of the above-described inventions, and an image pickup device that picks up an image of light transmitted through the optical member.

  An in-vehicle camera barrel according to an eighth aspect of the present invention includes the optical member according to any of the above-described inventions, and can be attached to the in-vehicle camera.

  In the first invention, the heat insulating member is provided between the lens outer peripheral surface and the lens barrel inner peripheral surface. When the lens barrel is made of metal (for example, aluminum), the thermal conductivity is about several hundred W / mK, whereas the thermal conductivity of the resin heat insulating material is, for example, 0.1 to 0.3 W. When the outside air temperature drops, even when the temperature of the lens barrel exposed to the outside air drops, the temperature of the lens barrel is not easily transmitted to the lens, and the water vapor in the air inside the lens barrel Condensation occurs on the inner peripheral surface of the lens barrel where the lens outer peripheral surface is not in contact. As a result, condensation on the lens surface is suppressed.

  In the second invention, the heat insulating film is formed on the inner peripheral surface of the lens barrel in contact with the outer peripheral surface of the lens. For example, the heat insulating film may be a resin film having a thermal conductivity of about 0.1 to 0.3 W / mK. As a result, when the outside air temperature decreases, even when the temperature of the lens barrel exposed to the outside air decreases, the temperature of the lens barrel is not easily transmitted to the lens, and water vapor in the air inside the lens barrel Condensation occurs on the surface of the surface where the heat insulating film is not formed, thereby suppressing condensation that occurs on the lens surface.

  In the third invention, a heat insulating film is formed on the outer peripheral surface of the lens. For example, the heat insulating film may be a resin film having a thermal conductivity of about 0.1 to 0.3 W / mK. When the outside air temperature decreases, even when the temperature of the lens barrel exposed to the outside air decreases, the temperature of the lens barrel is difficult to be transmitted to the lens, and water vapor in the air inside the lens barrel is in contact with the lens outer peripheral surface. No condensation on the inner surface of the lens barrel. As a result, condensation on the lens surface is suppressed.

  In the fourth invention, the heat conductivity of the heat insulating member is made smaller than the heat conductivity of the lens barrel. Thereby, when the outside air temperature is lowered, even when the temperature of the lens barrel exposed to the outside air is lowered, it is possible to make it difficult for the temperature of the lens barrel to be transmitted to the lens.

  In the fifth invention, an air layer is formed between the inner peripheral surface of the lens barrel and the outer peripheral surface of the lens. For example, a recess is provided around the outer peripheral surface of the lens that is in contact with the inner peripheral surface of the lens barrel so as to form an air layer with the lens barrel. An air layer is formed in the concave portion provided around the lens in contact with the inner peripheral surface of the lens barrel. When the outside air temperature decreases, the lens barrel is exposed even when the temperature of the lens barrel exposed to the outside air decreases. The temperature can be made difficult to be transmitted to the lens. Alternatively, a recess is provided around the inner peripheral surface of the lens barrel that is in contact with the outer peripheral surface of the lens so as to form an air layer with the lens. An air layer is formed in the concave portion provided around the lens in contact with the inner peripheral surface of the lens barrel. When the outside air temperature decreases, the lens barrel is exposed even when the temperature of the lens barrel exposed to the outside air decreases. The temperature can be made difficult to be transmitted to the lens. As a result, condensation occurs on the inner peripheral surface of the lens barrel that is not in contact with the lens, thereby suppressing condensation that occurs on the lens surface.

  In the sixth invention, the lens transmits far-infrared light. For example, the lens is made of a material such as zinc sulfide (ZnS) or germanium (Ge). Even when the thermal conductivity is high (for example, about several tens of W / mK) as compared with the thermal conductivity of 1 W / mK of glass, the dew condensation occurring on the lens can be suppressed.

  In the seventh invention, an imaging apparatus includes the above-described optical member. Thereby, even when the imaging apparatus is used for in-vehicle use exposed to the outside air, it is possible to suppress condensation on the lens surface.

  In the eighth invention, the lens barrel for the in-vehicle camera includes the above-described optical member and can be attached to the in-vehicle camera. Thereby, the lens barrel for in-vehicle cameras can suppress condensation on the lens surface even when used for in-vehicle use exposed to the outside air.

  In the present invention, by providing a resin heat insulating member between the outer peripheral surface of the lens housed in the lens barrel and the inner peripheral surface of the lens barrel, condensation occurring on the lens surface can be suppressed.

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is an exploded perspective view showing a configuration of a lens unit (optical member) 10 according to an embodiment of the present invention. The lens unit 10 includes an aluminum cylindrical lens barrel 19, lenses 11 and 12 housed inside the lens barrel 19, and an annular spacer 17 for fixing the lenses 11 and 12 with a predetermined separation dimension, The heat insulating rings 13 and 14 made of resin, stopper rings 15 and 16 for fixing the lenses 11 and 12 to the heat insulating rings 13 and 14, nuts 18, and the like are configured. In the example of FIG. 1, two lenses are accommodated, but the number of lenses is not limited to this, and may be one or three or more. In this case, a spacer or the like is additionally stored as appropriate.

  The lens unit 10 is disposed in the lens barrel 19 in the order of the heat insulating ring 14, the lens 12, the stopper ring 16, the spacer 17, the heat insulating ring 13, the lens 11, the stopper ring 15, and the nut 18. 13 and 14 can be assembled by being fixed to the lens barrel 19 with an adhesive.

  One end side of the heat insulating ring 13 is provided with a protruding piece (not shown) so that the inner diameter is smaller than the other end side, and the lens 11 mounted on the inner peripheral surface of the heat insulating ring 13 is fixed by the protruding piece. By attaching the stopper ring 15 to the heat insulation ring 13 to which the lens 11 is attached, the outer peripheral surface of the lens 11 is covered with the heat insulation ring 13. By mounting the heat insulating ring 13 on the inner peripheral surface of the lens barrel 19, the heat insulating ring 13 is disposed between the outer peripheral surface of the lens 11 and the inner peripheral surface of the lens barrel 19.

  Similarly, a projecting piece (not shown) is provided on one end side of the heat insulating ring 14 so that the inner diameter is smaller than the other end side, and the lens 12 mounted on the inner peripheral surface of the heat insulating ring 14 is fixed by the projecting piece. Is done. By attaching the stopper ring 16 to the heat insulation ring 14 to which the lens 12 is attached, the outer peripheral surface of the lens 12 is covered with the heat insulation ring 14. By mounting the heat insulating ring 14 on the inner peripheral surface of the lens barrel 19, the heat insulating ring 14 is disposed between the outer peripheral surface of the lens 12 and the inner peripheral surface of the lens barrel 19.

  The material of the heat insulation rings 13 and 14 is, for example, polycarbonate (PC). The material is not limited to this, and engineering plastics such as polyamide (PA) and polyethylene terephthalate (PET) may be used, or other general-purpose materials may be used in consideration of thermal conductivity, durability, workability, etc. Plastic may be used.

  The thermal conductivity of aluminum which is a material of the lens barrel 19 is about 237 W / mK. The thermal conductivity of germanium (Ge), which is the material of the lenses 11 and 12, is about 60 W / mK, and the thermal conductivity of zinc sulfide (ZnS) is about 27 W / mK. The thermal conductivity of the heat insulating rings 13 and 14 can be about 0.1 to 0.3 W / mK.

  FIG. 2 is a cross-sectional view of a main part of the lens unit 10 according to the present invention. In FIG. 2, since the lens unit 10 is symmetrical with respect to the optical axis, only half of the lens unit 10 is shown. As shown in FIG. 2, the heat insulating ring 13 is disposed between the outer peripheral surface of the lens 11 and the inner peripheral surface of the lens barrel 19, and the lens 11 is not in direct contact with the lens barrel 19. Further, a heat insulating ring 14 is disposed between the outer peripheral surface of the lens 12 and the inner peripheral surface of the lens barrel 19, and the lens 12 is not in direct contact with the lens barrel 19.

  As shown in FIG. 2, by making the resin heat insulating rings 13 and 14 a double structure sandwiched between the lens barrel 19 and the lenses 11 and 12, the heat held by the lenses 11 and 12 is transferred to the lens barrel 19. Even when the temperature of the lens barrel 19 facing the outside air decreases due to a decrease in the outside air temperature, a rapid temperature change of the lenses 11 and 12 can be suppressed. Thereby, water vapor in the air in the region surrounded by the lens barrel 19 and the lenses 11 and 12 is mainly condensed on the inner surface of the lens barrel 19 excluding the heat insulating rings 13 and 14. Condensation on the surface of the film can be suppressed.

  In addition, by using the heat insulating rings 13 and 14, for example, there is no need to provide a moisture absorbent for preventing condensation inside the lens unit, and the work of periodically replacing the moisture absorbent becomes unnecessary, and a moisture absorbent is provided. Extra space is not required.

  Even if the lens barrel 19 is made of a metal such as aluminum having a high thermal conductivity, the dew condensation occurring on the lenses 11 and 12 can be suppressed, so that the lens barrel 19 can be maintained at a required strength. For this reason, it is possible to sufficiently withstand use even in an environment where vibration or impact is applied, particularly when used in an in-vehicle imaging device.

  FIG. 3 is a block diagram illustrating a configuration of the imaging apparatus 100 including the lens unit 10 according to the present invention. The imaging device (vehicle camera) 100 includes a lens unit 10, an imaging device 30, an image processing unit 40, an image memory 50, a communication interface unit 60, and the like. In this case, the lens barrel 19 of the lens unit 10 includes, for example, a screw portion that is attached to the housing of the imaging device so as to be configured as one component (vehicle camera barrel) of the imaging device 100. In addition, the attachment method is not limited to this.

  The lens unit 10 transmits far-infrared light and collects it on the surface of the image sensor 30.

  The imaging device 30 is a far infrared sensor such as a bolometer, a pyroelectric sensor, or an SOI diode, for example. For example, far infrared light having a wavelength of 7 to 14 μm is converted into a luminance signal, and the converted luminance signal is an image processing unit. Output to 40.

  The image processing unit 40 includes an LSI, converts a luminance signal input from the image sensor 30 into a digital signal, corrects variations in the image sensor 30, and calculates an output value (luminance signal) of the image sensor 30. Processing, defect element correction processing, gain control processing, and the like are performed, and the processed imaging data is stored in the image memory 50. Note that it is not essential to temporarily store the imaging data in the image memory 50, and it can also be output to the outside (for example, a monitor) via the communication interface unit 60.

  The communication interface unit 60 outputs imaging data to a monitor, for example, via a video cable compatible with an analog video system such as NTSC or a digital video system.

Embodiment 2
In the first embodiment, the heat insulating ring is used. However, the present invention is not limited to this. For example, a heat insulating film can be formed on the outer peripheral surface of the lens.

  FIG. 4 is a cross-sectional view of a main part of the lens unit 10 of the second embodiment. As shown in FIG. 4, a resin film 11 a is formed on the outer peripheral surface of the lens 11 (that is, the portion that contacts the lens barrel 19). As the material of the resin film 11a, the same material as that of the heat insulating rings 13 and 14 can be used. The thermal conductivity of the resin film 11a can be about 0.1 to 0.3 W / mK, for example. Moreover, the film thickness of the resin film 11a can also be set suitably. Similarly, a resin film 12a made of the same material as that of the resin film 11a is formed on the outer peripheral surface of the lens 12 (that is, the portion in contact with the lens barrel 19).

  This makes it difficult for the heat held in the lenses 11 and 12 to be transmitted to the lens barrel 19, and even if the outside air temperature decreases and the temperature of the lens barrel 19 facing the outside air decreases, the lenses 11 and 12 suddenly change. Temperature change can be suppressed. As a result, water vapor in the air in the region surrounded by the lens barrel 19 and the lenses 11 and 12 is mainly condensed on the inner surface of the lens barrel 19, and the condensation generated on the surfaces of the lenses 11 and 12 is suppressed. be able to.

Embodiment 3
In the second embodiment, the heat insulating film is formed on the outer peripheral surface of the lens. However, the present invention is not limited to this. For example, the heat insulating film is formed on the inner peripheral surface of the lens barrel that comes into contact with the outer peripheral surface of the lens. You can also

  FIG. 5 is a cross-sectional view of a main part of the lens unit 10 according to the third embodiment. As shown in FIG. 5, a resin film 19a is formed on the inner peripheral surface of the lens barrel 19 with which the outer peripheral surface of the lens 11 abuts. As the material of the resin film 19a, the same material as that of the heat insulating rings 13 and 14 can be used. The thermal conductivity of the resin film 19a can be about 0.1 to 0.3 W / mK, for example. The film thickness of the resin film 19a can also be set as appropriate. Similarly, a resin film 19b made of the same material as the resin film 19a is formed on the inner peripheral surface of the lens barrel 19 with which the outer peripheral surface of the lens 12 abuts.

  This makes it difficult for the heat held in the lenses 11 and 12 to be transmitted to the lens barrel 19, and even if the outside air temperature decreases and the temperature of the lens barrel 19 facing the outside air decreases, the lenses 11 and 12 suddenly change. Temperature change can be suppressed. Thereby, water vapor in the air in the region surrounded by the lens barrel 19 and the lenses 11 and 12 is mainly condensed on the inner surface of the lens barrel 19 where the resin films 19a and 19b are not formed. , 12 on the surface can be suppressed.

Embodiment 4
In the first embodiment, the heat insulating ring is used. However, the present invention is not limited to this. For example, an air layer can be formed between the lens and the lens barrel.

  FIG. 6 is a cross-sectional view of a main part of the lens unit 10 according to the fourth embodiment. As shown in FIG. 6, a recess 11 b is provided on the outer peripheral surface of the lens 11 so as to form an air layer between the lens 11 and the inner peripheral surface of the lens barrel 19. Similarly, a recess 12b is provided on the outer peripheral surface of the lens 12 so as to form an air layer between the lens 12 and the inner peripheral surface of the lens barrel 19. The thermal conductivity of air is about 0.024 W / mK, and the heat held by the lenses 11 and 12 is prevented from being transmitted to the lens barrel 19.

  This makes it difficult for the heat held in the lenses 11 and 12 to be transmitted to the lens barrel 19, and even if the outside air temperature decreases and the temperature of the lens barrel 19 facing the outside air decreases, the lenses 11 and 12 suddenly change. Temperature change can be suppressed. As a result, water vapor in the air in the region surrounded by the lens barrel 19 and the lenses 11 and 12 is mainly condensed on the inner surface of the lens barrel 19, and the condensation generated on the surfaces of the lenses 11 and 12 is suppressed. be able to.

Embodiment 5
FIG. 7 is a cross-sectional view of a main part of the lens unit 10 according to the fifth embodiment. As shown in FIG. 7, a recess 19 c is provided around the inner peripheral surface of the lens barrel 19 with which the outer peripheral surface of the lens 11 abuts so as to form an air layer between the lens 11 and the inner peripheral surface of the lens barrel 19. Similarly, a recess 19 d is provided around the inner peripheral surface of the lens barrel 19 with which the outer peripheral surface of the lens 12 abuts so as to form an air layer between the lens 12 and the inner peripheral surface of the lens barrel 19. Further, as shown in FIG. 7, a spacer 20 may be arranged to adjust the position of the lens 12. In this case as well, as in the fourth embodiment, condensation occurring on the surfaces of the lenses 11 and 12 can be suppressed.

  As described above, in the present invention, even when the heat held by the lens is difficult to be transmitted to the lens barrel and the temperature of the lens barrel facing the outside air decreases due to a decrease in the outside air temperature, Can be suppressed. Thereby, water vapor in the air in the region surrounded by the lens barrel and the lens mainly condenses on the inner surface of the lens barrel, so that the dew condensation that occurs on the surface of the lens can be suppressed.

  In the first to fifth embodiments described above, examples of lens units using lenses made of a material that can transmit far-infrared light such as zinc sulfide and germanium have been described. However, the present invention is not limited to far-infrared light. The present invention can also be applied to a lens unit and an imaging apparatus using a visible light lens using glass.

  In order to further suppress dew condensation occurring on the lens surface, the above-described embodiments can be combined. For example, the second embodiment and the fifth embodiment may be combined, or the third embodiment and the fourth embodiment may be combined.

It is a disassembled perspective view which shows the structure of the lens unit which concerns on embodiment of this invention. It is principal part sectional drawing of the lens unit which concerns on this invention. It is a block diagram which shows the structure of the imaging device provided with the lens unit which concerns on this invention. 6 is a cross-sectional view of a main part of a lens unit according to Embodiment 2. FIG. 6 is a cross-sectional view of a main part of a lens unit according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view of a main part of a lens unit according to a fourth embodiment. FIG. 10 is a cross-sectional view of a main part of a lens unit according to a fifth embodiment.

Explanation of symbols

10 Lens unit (optical member)
DESCRIPTION OF SYMBOLS 11, 12 Lens 11a, 12a, 19a, 19b Resin film 11b, 12b, 19c, 19d Recessed part 13, 14 Heat insulation ring 15, 16 Stopper ring 17, 20 Spacer 18 Nut 19 Lens barrel 30 Image sensor 40 Image processing part 50 Image memory 60 Communication interface section

Claims (8)

In an optical member that houses a lens inside a lens barrel,
An optical member comprising a resin heat insulating member between the lens outer peripheral surface and the lens barrel inner peripheral surface. The heat insulating member is
The optical member according to claim 1, wherein the optical member is a heat insulating film formed on an inner peripheral surface of the lens barrel on which the outer peripheral surface of the lens abuts. The heat insulating member is
The optical member according to claim 1, wherein the optical member is a heat insulating film formed on the outer peripheral surface of the lens.   4. The optical member according to claim 1, wherein a thermal conductivity of the heat insulating member is smaller than a thermal conductivity of the lens barrel. In an optical member that houses a lens inside a lens barrel,
An optical member, wherein an air layer is formed between a lens barrel inner peripheral surface and a lens outer peripheral surface.   The optical member according to claim 1, wherein the lens is configured to transmit far infrared light.   An image pickup apparatus comprising: the optical member according to claim 1; and an image pickup device that picks up an image of light transmitted through the optical member.   An in-vehicle camera barrel comprising the optical member according to any one of claims 1 to 6 and capable of being attached to an in-vehicle camera.

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