JP2009093010A - Lens unit, image pickup apparatus, image processing system, and method of manufacturing lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens unit which can reduce the number of components and assembly man-hours by eliminating spacers. <P>SOLUTION: In a lens unit A built by inserting a first to third infrared lenses 21, 22, 23 into a lens-barrel 1, first to third recesses 11a, 12a, 13a are formed inside the lens-barrel 1 to fit flanges 21a, 22a, 23a of the first to third infrared lenses 21, 22, 23. When the lens-barrel 1 and the infrared lenses 21, 22, 23 are in a second temperature range, the lens-barrel 1 and the first to third infrared lenses 21, 22, 23 are constituted so that the inner diameters of the inner surfaces 11, 12, 13 of the lens-barrel 1 become larger than the first to third infrared lenses 21, 22, 23 at the back of the first to third recesses 11a, 12a, 13a in the optical axis direction, and larger than the outer diameters of the first to third infrared lenses 21, 22, 23 in front of the recesses 11a, 12a, 13a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lens unit in which a plurality of lenses are inserted into a lens barrel, an imaging apparatus including the lens unit, an image processing system, and a method for manufacturing the lens unit.

  A driving support system that issues an alarm and alerts the driver when an obstacle such as a pedestrian or an animal that may cause a collision is detected by imaging a vehicle periphery with a far-infrared imaging device mounted on the automobile. It has been put into practical use. The far-infrared imaging device includes a lens unit that collects infrared rays, an imaging unit, and the like.

FIG. 12 is a side sectional view schematically showing a conventional lens unit. The conventional lens unit includes first to third infrared lenses 21, 22, 23 inserted into the lens barrel 301, spacers 3, 4 interposed between the lenses, and a lens holder 5.
The assembling method of the lens unit is as follows. First, the lens barrel 301, the first to third lenses 21, 22, 23, and the like are prepared, and the first infrared lens 21, the spacer 3, the second infrared lens 22, the spacer 4, and the third infrared lens 23 are prepared in the lens barrel 301. Insert sequentially. Then, the first to third infrared lenses 21, 22, and 23 are positioned and fixed by screwing the lens holder 5 into the lens barrel 301 and pressing each lens.
Japanese Patent Laid-Open No. 10-068859

  However, since the conventional lens unit requires the spacers 3 and 4 in order to keep the distance between the first to third infrared lenses constant, the spacers 3 and 4 are unnecessary from the viewpoint of the number of parts and the assembly process. It was hoped to do.

  The present invention has been made in view of such circumstances, and provides a lens unit, an imaging device, an image processing system, and a manufacturing method of the lens unit that can reduce the number of parts and the number of assembly steps by eliminating a spacer. For the purpose.

  A lens unit according to a first aspect of the present invention is a lens unit in which a plurality of lenses are inserted into a lens barrel, and the lens barrel includes a plurality of fitting recesses into which the peripheral edge of each lens is fitted on the inner peripheral surface. When the lens barrel and the lens are in the first temperature range, the inner diameter of the lens barrel is smaller than the outer diameter of the lens and in the second temperature range higher than the first temperature range. Has a linear expansion coefficient larger than the outer diameter of the lens.

  In the lens unit according to the second aspect of the invention, when the lens barrel and the lens are in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of the fitting recess fits in the fitting recess. The inner diameter of the inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the fitting recess is larger than the outer diameter of the lens fitted in the fitting recess. .

  A lens unit according to a third aspect of the present invention is a lens unit in which a plurality of lenses are inserted into a lens barrel, and the lens barrel includes a plurality of fitting recesses into which the peripheral edge of each lens is fitted on the inner peripheral surface. When the lens barrel and the lens are in the first temperature range, the inner diameter of the lens barrel is smaller than the outer diameter of the lens, and the lens barrel is in the second temperature range higher than the first temperature range, The lens barrel has a linear expansion coefficient that makes the inner diameter of the lens barrel larger than the outer diameter of the lens.

  In the lens unit according to a fourth aspect of the present invention, when the lens barrel is in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of each fitting recess is fitted into the fitting recess. It is smaller than the outer diameter of the lens, and the inner diameter of the inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the fitting recess is larger than the outer diameter of the lens fitted in the fitting recess.

  The lens unit according to a fifth aspect of the present invention is characterized in that when the lens barrel and the lens are at a predetermined temperature within a first temperature range, the outer diameter of the lens is equal to the inner diameter of the fitting recess.

  The lens unit according to a sixth aspect of the invention is characterized in that, when the lens barrel and the lens are at a predetermined temperature within a first temperature range, the widths of the peripheral edge of the lens and the fitting recess in the optical axis direction are equal. To do.

  The lens unit according to a seventh aspect of the present invention is that the lens includes any one of infrared transmissive zinc sulfide, zinc selenide, germanium, chalcogenite glass, or silicon, and the lens barrel is aluminum. Features.

  An imaging device according to an eighth invention includes the lens unit according to any one of the first to seventh inventions, and an imaging unit that captures an image formed by the lens.

  An image processing system according to a ninth aspect of the present invention is a lens unit according to any one of the first to seventh aspects of the invention arranged in a vehicle, an imaging unit that captures an image formed by the lens, And an image processing unit that detects an object based on image data obtained by imaging by the imaging unit.

  A lens unit manufacturing method according to a tenth aspect of the present invention is the lens unit manufacturing method in which a plurality of lenses are inserted into a lens barrel, and the plurality of lenses and a plurality of fitting recesses into which the periphery of each lens is fitted. The lens barrel and the lens are heated, the lens barrel and the lens are heated, the lens is inserted into the lens barrel, the lens barrel and the lens are cooled to a first temperature range, and the lens is It is made to fit in the said fitting recessed part.

  A lens unit manufacturing method according to an eleventh aspect of the present invention is a lens unit manufacturing method in which a plurality of lenses are inserted into a lens barrel, and the plurality of lenses and a plurality of fitting recesses into which the periphery of each lens is fitted. And a lens barrel provided on the inner peripheral surface, heating the lens barrel, inserting the lens into the lens barrel, cooling the lens barrel to a first temperature range, and fitting the lens into the fitting recess It is made to fit in.

In the first, eighth, ninth, and tenth inventions, when the lens barrel and the lens are in the first temperature range, the peripheral edge of the lens is fitted in the fitting recess formed on the inner peripheral surface of the lens barrel. Since the outer diameter of the lens is larger than the inner diameter of the inner peripheral surface of the lens barrel, each lens is fixed to the lens barrel while keeping the distance between the lenses constant. Therefore, a spacer that keeps the distance between the lenses is unnecessary.
On the other hand, when the lens barrel and the lens are in the second temperature range higher than the first temperature range, the inner diameter of the lens barrel is larger than the outer diameter of the lens. Therefore, by heating the lens barrel and the lens to the second temperature range, the lens can be inserted into the lens barrel and moved to the position of the fitting recess. Further, by cooling to the first temperature range, the lens can be fitted into the fitting recess of the lens barrel.

  When manufacturing the lens unit, first, the lens barrel and the lens are prepared. Then, the lens barrel and the lens are heated to the second temperature range. This is because the lens barrel and the lens are thermally expanded so that the lens can be inserted into the lens barrel. Note that the lens barrel and the lens may be heated to different temperatures within the second temperature range. Therefore, the magnitude relationship between the linear expansion coefficients of the lens barrel and the lens is not particularly limited. Next, each lens is inserted into the lens barrel. Next, the lens barrel and the lens are cooled to the first temperature range. This is because the lens barrel and the lens are again thermally contracted, and the lens is fitted into the fitting recess of the lens barrel. By adopting a manufacturing method in which the lens is fixed to the lens barrel by heating and cooling (hereinafter referred to as shrink fitting), the spacer becomes unnecessary, and the manufacturing process for interposing the spacer between the lenses becomes unnecessary. .

  In the second, eighth, ninth, and eleventh inventions, the inner peripheral surface of the lens barrel has a stepped shape, and when a plurality of lenses are shrink-fitted into the lens barrel, each lens has a corresponding fit. It is formed so as to be locked at the position of the joint recess. Specifically, even when the lens barrel and the lens are in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of each fitting recess should be fitted into the fitting recess. Therefore, the lens does not fall out from the other end side to the one end side, and the lens is locked at the position of the fitting recess. When the lens barrel and the lens are in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the fitting recess is larger than the outer diameter of the lens to be fitted in the fitting recess. Thus, the lens can be inserted from the other end side. Therefore, by inserting from the other end side of the lens barrel in order from the lens having the smallest outer diameter, a plurality of lenses can be easily positioned in the corresponding fitting recesses, and each lens is cooled by cooling the lens and the lens. Can be fitted into the fitting recess.

In the third invention, when the lens barrel and the lens are in the first temperature range, the peripheral edge of the lens is fitted in the fitting recess formed in the inner peripheral surface of the lens barrel, and the outer diameter of the lens Is larger than the inner diameter of the inner peripheral surface of the lens barrel, so that the lens is fixed to the lens barrel while keeping the distance between the lenses constant. Therefore, a spacer that keeps the distance between the lenses is unnecessary.
On the other hand, when the lens barrel is in the second temperature range higher than the first temperature range, the inner diameter of the lens barrel is larger than the outer diameter of the lens. Therefore, by heating the lens barrel to the second temperature range, the lens can be inserted into the lens barrel and moved to the position of the fitting recess. Further, by cooling to the first temperature range, the lens can be fitted into the fitting recess of the lens barrel.

  When manufacturing the lens unit, first, the lens barrel and the lens are prepared. Then, the lens barrel is heated to the second temperature range. This is because the lens barrel is thermally expanded so that the lens can be inserted into the lens barrel. Next, each lens is inserted into the lens barrel. Next, the lens barrel is cooled to the first temperature range. This is because the lens barrel is thermally contracted again to fit the lens into the fitting recess of the lens barrel. By adopting a manufacturing method in which a lens is shrink-fitted in a lens barrel in this way, a spacer is not required, and a manufacturing process in which the spacer is interposed between the lenses is also unnecessary.

  In the fourth invention, the inner peripheral surface of the lens barrel is stepped, and when a plurality of lenses are shrink-fitted into the lens barrel, each lens is locked at the position of the corresponding fitting recess. Is formed. Specifically, even when the lens barrel is in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of each fitting recess is outside the lens to be fitted in the fitting recess. Since the lens is formed to be smaller than the diameter, the lens does not fall out from the other end side to the one end side, and the lens is locked at the position of the fitting recess. When the lens barrel is in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the fitting recess is larger than the outer diameter of the lens to be fitted into the fitting recess. Since it is formed, the lens can be inserted from the other end side. Therefore, by inserting the lens from the other end side of the lens barrel in order from the lens having the smallest outer diameter, a plurality of lenses can be easily positioned in the corresponding fitting recesses, and each lens is fitted by cooling the lens barrel. It can be fitted into the mating recess.

  In the fifth invention, when the lens and the lens barrel are in the first temperature range, the outer diameter of the lens is equal to the inner diameter of the fitting recess. Therefore, the lens can be positioned in the radial direction at a predetermined temperature.

  In the sixth invention, when the lens and the lens barrel are in the first temperature range, the optical axis direction width of the peripheral portion of the lens and the optical axis direction width of the fitting recess are equal. Accordingly, the lens can be positioned in the optical axis direction at a predetermined temperature.

In the seventh invention, the lens contains any one of zinc sulfide, zinc selenide, germanium, chalcogenite glass, or silicon, and transmits infrared rays. Therefore, an infrared image can be formed. In the imaging apparatus, an image captured with infrared rays can be obtained, and in the image processing system, an object can be detected from an image captured with infrared rays.
Further, since the lens barrel is made of aluminum, it is easy to process the fitting recess, and it is suitable for shrink fitting because it has a higher linear expansion coefficient than other metals such as brass.

  According to the present invention, a lens positioning spacer in a lens unit, an imaging apparatus including the lens unit, and an image processing system is obtained by shrink-fitting a lens into a fitting recess formed on the inner peripheral surface of the lens barrel. Can be eliminated, and the number of parts and assembly man-hours can be reduced.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a side sectional view schematically showing a lens unit A according to Embodiment 1 of the present invention. The lens unit A according to Embodiment 1 of the present invention includes a lens barrel 1 and first to third infrared lenses 21, 22, and 23 that are sequentially inserted into the lens barrel 1.

  The first to third infrared lenses 21, 22, and 23 are sintered bodies obtained by sintering a zinc sulfide raw material powder by a hot press method, and are transmissive to infrared rays in the 8 to 12 μm band. Yes. By molding each lens with zinc sulfide, the first to third infrared lenses 21, 22, and 23 can be manufactured at low cost. The first infrared lens 21 is a meniscus lens having a convex surface on the front side, the second infrared lens 22 is a meniscus lens having a convex surface on the back side, and the third infrared lens 23 is a meniscus lens having a convex surface on the front side. The front side shows the upper side in FIG. 1, and the back side shows the lower side in FIG. The first to third infrared lenses 21, 22, and 23 are provided with flanges (peripheral portions) 21 a, 22 a, and 23 a on the outer periphery that are annular in front view or rear view. The flange portions 21 a, 22 a, and 23 a are for holding the first to third infrared lenses 21, 22, and 23 at predetermined locations in the lens barrel 1.

  In addition, although zinc sulfide was illustrated as a material of the 1st thru | or 3rd infrared lens 21,22,23, it forms with another infrared-permeable material, for example, zinc selenide, germanium, chalcogenite glass, or silicon. You may comprise as follows.

The surface on the front side of the third infrared lens 23 is covered with an intermediate layer and a DLC film (not shown). By forming the DLC film, the environmental resistance of the third infrared lens 23 can be improved. Further, the number of parts such as a protective plate and a protective net and the number of assembly steps can be reduced.
The DLC film is an amorphous carbon thin film having a structure similar to diamond. The DLC film has a surface hardness of 2000 or more in Knoop hardness, is chemically stable, and has excellent permeability from the visible to the infrared region. The DLC film has a thickness of 0.2 μm or more and 20 μm or less, and a refractive index of 2.0 to 2.4. The film thickness of the DLC film is preferably 2 μm or less in consideration of infrared transmittance.
The intermediate layer increases the adhesion between the DLC film and the third infrared lens 23. The intermediate layer is made of, for example, an oxide such as yttrium oxide Y ₂ O ₃ , aluminum oxide Al ₂ O ₃ , titanium oxide TiO ₃ , magnesium fluoride MgF ₂ , yttrium fluoride YF ₃ , lanthanum fluoride LaF ₃ , germanium fluoride. Fluoride such as GeF ₃ , germanium Ge, silicon Si, gallium phosphide GaP, boron phosphide BP, etc., and the film thickness is 0.02 μm or more and 25 μm or less. The intermediate layer is excellent in adhesion with the DLC film and the third infrared lens 23. The film thickness of the intermediate layer is preferably 0.2 μm or less considering the infrared transmittance.
Note that the DLC film and the intermediate layer are formed by a sputtering method, a vacuum evaporation method, an ion plating method, a CVD method, a plasma CVD method, or the like.
Further, the coating temperature of the DLC film or the like is about 400 ° C., and it will not be damaged or peeled even when heated to a shrink fitting temperature of about 200 ° C. as will be described later.

The lens barrel 1 is formed of aluminum having a larger linear expansion coefficient than the first to third infrared lenses 21, 22, and 23. Incidentally, the linear expansion coefficient of the first to third infrared lens 21, 22 and 23 is ^{7.0 × 10 -6 (1 / K} ), the coefficient of linear expansion of the lens barrel 1 is 23.1 × 10 ^- it is a ⁶ (1 / K).
The lens barrel 1 is provided with inner peripheral surfaces 10, 11, 12, and 13 having different inner diameters in a stepped manner, and first to third fitting recesses 11a, 12a, and 13a are provided on the inner peripheral surfaces 11, 12, and 13, respectively. Is formed. The inner diameters of the inner peripheral surfaces 10, 11, 12, 13 and the first to third fitting recesses 11 a, 12 a, 13 a are the same as the first to third infrared lenses 21, 22, 23 in the lens barrel 1. It has dimensions necessary for shrink fitting into the fitting recesses 11a, 12a, 13a.

The inner diameter of the inner peripheral surface 10 formed on the back side from the first fitting recess 11a is smaller than the outer diameter of the first infrared lens 21 at room temperature (25 ° C.) to a predetermined shrink fitting temperature (200 ° C.). It is such a dimension. The inner diameter of the inner peripheral surface 11 formed on the front side from the first fitting recess 11a is smaller than the outer diameter of the first infrared lens 21 at room temperature, and is smaller than the outer diameter of the first infrared lens 21 at the shrink fitting temperature. It is a dimension that becomes larger.
The inner diameter of the first fitting recess 11a and the width in the optical axis L direction are dimensions that are substantially equal to the outer diameter of the first infrared lens 21 and the width in the optical axis L direction at room temperature. The temperature at which the widths are equal is not limited to room temperature, but may be configured such that the widths are equal at the temperature of the environment in which the lens unit A is used. For example, in the case of an in-vehicle lens unit A, the width may be configured to be equal to the temperature of the lens unit A when mounted on a vehicle.

FIG. 2 is a chart showing an example of the dimensions of the inner peripheral surfaces of the first infrared lens 21 and the lens barrel 1. For example, the outer diameter of the first infrared lens 21 is 20 (mm) at 25 ° C. at room temperature, the inner diameter of the inner peripheral surface 11 on the front side from the first fitting recess 11a is 19.95 (mm), and the first fitting recess. The inner diameter of the inner peripheral surface 10 on the back side from 11a is 14.4 (mm). The linear expansion coefficient of aluminum constituting the lens barrel 1 is 26.4 × 10 ⁻⁶ (1 / K), and the linear expansion coefficient of the first infrared lens 21 is 7.0 × 10 ⁻⁶ (1 / K). When the lens barrel 1 and the first infrared lens 21 are heated to the shrink fitting temperature of 200 ° C., the inner diameter of the inner peripheral surface 11 is 19.95 × (1 + 26.4 × 10 ⁻⁶ × 175) = 20.039, The outer diameter of one infrared lens 21 is 20 × (1 + 7.0 × 10 ⁻⁶ × 175) = 20.025. Therefore, by inserting the first infrared lens 21 from the front side, the first infrared lens 21 can pass through the inner peripheral surface 11 portion and move to the first fitting recess 11a.
When the lens barrel 1 and the first infrared lens 21 are heated to a shrink fitting temperature of 200 ° C., the inner diameter of the inner peripheral surface 10 is 14.4 × (1 + 26.4 × 10 ⁻⁶ × 175) = 14.5, The outer diameter of the first infrared lens 21 is 20 × (1 + 7.0 × 10 ⁻⁶ × 175) = 20.025. Accordingly, the first infrared lens 21 inserted from the front side does not pass through the inner peripheral surface 10 and fall off to the back side. That is, the first infrared lens 21 is locked to the annular surface 14 of the protruding portion formed on the inner peripheral surface of the rear side end of the lens barrel 1.
When the lens barrel 1 and the first infrared lens 21 are cooled to room temperature in a state where the first infrared lens 21 is positioned in the first fitting recess 11a, the inner diameter of the inner peripheral surface 11 becomes 19.95 (mm) again. Since the outer diameter of the infrared lens 21 is 20 (mm), the first infrared lens 21 cannot move in the direction of the optical axis L while being fitted in the first fitting recess 11a and is fixed.

  Similarly, the inner peripheral surface 11 is formed on the back side of the second fitting recess 12a, and the inner peripheral surface 12 is formed on the front side. The inner diameter of the inner peripheral surface 11 is a dimension that is smaller than the outer diameter of the second infrared lens 22 at room temperature or a predetermined shrink fitting temperature. The inner peripheral surface 12 has an inner diameter that is smaller than the outer diameter of the second infrared lens 22 at room temperature and larger than the outer diameter of the second infrared lens 22 at the shrink fitting temperature.

  The inner diameter of the second fitting recess 12a and the width in the optical axis L direction are dimensions that are substantially equal to the outer diameter of the second infrared lens 22 and the width in the optical axis L direction at room temperature.

  Similarly, an inner peripheral surface 12 is formed on the back side of the third fitting recess 13a, and an inner peripheral surface 13 is formed on the front side. The inner diameter of the inner peripheral surface 12 is a dimension that is smaller than the outer diameter of the third infrared lens 23 at room temperature or a predetermined shrink fitting temperature. The inner diameter of the inner peripheral surface 13 is smaller than the outer diameter of the third infrared lens 23 at room temperature and larger than the outer diameter of the third infrared lens 23 at the shrink fitting temperature.

  The inner diameter of the third fitting recess 13a and the width in the optical axis L direction are dimensions that are substantially equal to the outer diameter of the third infrared lens 23 and the width in the optical axis L direction at room temperature.

  A male screw 15 for fixing to the base 7 having the imaging unit 61 is formed on the outer peripheral surface of the rear side end of the lens barrel 1.

  FIG. 3 is a process diagram illustrating an assembling method of the lens unit A according to Embodiment 1 of the present invention, and FIGS. 4 to 6 are side cross-sectional views schematically showing the lens unit A in each assembling process. First, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 constituting the lens unit A shown in FIG. 1 are prepared (step S11), and the lens barrel 1 and the first to third infrared lenses are prepared. 21, 22, and 23 are heated to a shrink fit temperature of 200 ° C. (step S 12).

  Then, as shown in FIG. 4, the first infrared lens 21 having the smallest outer diameter is inserted into the lens barrel 1 (step S13). Since the inner diameter of the inner peripheral surface 11 is larger than the outer diameter of the first infrared lens 21 at the shrink fitting temperature, the first infrared lens 21 can be inserted up to the position of the first fitting recess 11a. Moreover, since the inner diameter of the inner peripheral surface 10 on the back side from the first fitting recess 11a is smaller than the first infrared lens 21 even at the shrink fitting temperature, the first infrared lens 21 is not dropped out to the back side. It can be locked at the position of the first fitting recess 11a.

  Next, as shown in FIG. 5, the second infrared lens 22 is inserted into the lens barrel 1 (step S14). At the shrink fitting temperature, like the first infrared lens 21, the second infrared lens 22 can be moved to the position of the second fitting recess 12a and can be locked at this position.

  Next, as shown in FIG. 6, the third infrared lens 23 is inserted into the lens barrel 1 (step S15). At the shrink fitting temperature, like the first infrared lens 21, the third infrared lens 23 can be moved to the position of the third fitting recess 13a, and can be locked at this position.

  Then, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 are cooled to room temperature, for example, 25 ° C. (step S16). When cooled to room temperature, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 are thermally contracted, and the first to third infrared lenses 21, 22, and 23 are first to first as shown in FIG. 3 Fits into the recessed portions 11a, 12a, 13a and is positioned.

Next, an application example of the lens unit A according to the first embodiment will be described.
FIG. 7 is an explanatory diagram conceptually showing the image processing system according to the first embodiment. The image processing system according to the first embodiment of the present invention includes two far-infrared imaging devices B and an image processing device 91 mounted on the front portion of the vehicle. By capturing a common imaging target with the two far-infrared imaging devices B, the parallax of the imaging target in both captured images can be calculated, and the distance to the imaging target can be obtained by the principle of triangulation.

  FIG. 8 is a side sectional view schematically showing the configuration of the far-infrared imaging device B including the lens unit A according to the first embodiment, and FIG. 9 is a block diagram showing the configuration of the far-infrared imaging device B. . The far-infrared imaging device B includes a lens unit A, an imaging unit 61, a base 7, and a housing 8. The lens unit A, the imaging unit 61, and the base 7 are accommodated in the housing 8.

  The base 7 includes a substrate support 7a that supports the substrate on which the imaging unit 61 is disposed, a holding cylinder support 7b provided at a front side end of the substrate support 7a, and a front side from the holding cylinder support 7b. And a lens unit holding cylinder 7c projecting from the lens. The lens unit holding cylinder 7c has a larger diameter than the lens barrel 1, and the male screw 15 of the lens unit A is screwed into the lens unit holding cylinder 7c.

  The imaging unit 61 is disposed at an appropriate position on the back side of the first to third infrared lenses 21, 22, and 23 provided in the lens unit A, and includes an imaging device such as a thermopile.

  The far-infrared imaging device B includes a signal processing unit 62, an image memory 63 for temporary storage, and a video output unit 64, and each component unit is connected by a wiring 65.

  The imaging unit 61 continuously or intermittently performs an imaging process for converting an image formed by the infrared lens of the lens unit A into an electrical signal, and generates, for example, 30 pieces of image data (image frame) per second. To the signal processing unit 62.

  The signal processing unit 62 AD converts the luminance signal into digital image data, executes various correction processes on the AD-converted image data, and transmits the image data via the cable 94 connected to the video output unit 64. Is transmitted to the image processing apparatus 91.

  FIG. 10 is a block diagram illustrating a configuration of the image processing apparatus 91. The image processing apparatus 91 includes a control unit 91a, an image memory 91b, a RAM 91c, a video input unit 91d, a video output unit 91e, and a communication interface unit 91f.

  The far-infrared imaging device B is connected to the video input unit 91d via the cable 94, and the image data transmitted from the far-infrared imaging device B is input. The image data input to the video input unit 91d is sequentially stored in the image memory 91b in units of one frame.

  A display device 92, a liquid crystal display, an in-meter display, a navigation display, a head-up display, and the like are connected to the video output unit 91e via a cable 95. The video output unit 91e appropriately transmits the input image data to the display device 92, and causes the display device 92 to display an image obtained by the far-infrared imaging device B. For example, the images obtained by the far-infrared imaging device B are displayed in parallel in the horizontal direction.

  An alarm device 93 is connected to the communication interface unit 91f via an in-vehicle LAN cable 96 compliant with CAN, and an alarm signal according to the control of the control unit 91a is transmitted to the alarm device 93 via the communication interface unit 91f. It is configured to be.

  The alarm device 93 includes a buzzer, a speaker, a display unit, and the like, and when a pedestrian that may possibly come into contact or collide is detected, the alarm device 93 outputs a sound to that effect, a warning sound, or the like. For example, characters such as “DANGER” can be displayed and a warning sound can be emitted. The detected pedestrian image can also be displayed on the display device 92.

  The image memory 91b is an SRAM, flash memory, SDRAM, or the like, and temporarily stores image data input from the far-infrared imaging device B via the video input unit 91d.

  The control unit 91a reads the image data stored in the image memory 91b in units of frames, and performs various processes such as detecting obstacles such as animals and pedestrians based on the read image data. For example, the control unit 91a detects an obstacle by extracting edges from the image data and grouping edges having substantially the same parallax. Hereinafter, an example of an obstacle detection method will be described.

  The controller 91a performs edge extraction processing on a far infrared image (hereinafter referred to as a reference image) acquired from one far infrared imaging device B to extract an edge point. Since the infrared radiation characteristic differs for each object, the boundary between the obstacle and the background is extracted as an edge point. Specifically, the control unit 91a extracts edges by filtering processing and threshold processing by an edge extraction operator. The edge extraction operator is preferably a Pruit wit operator that extracts vertical edges.

  Next, the control unit 91a specifies an edge group including a plurality of adjacent edge points, for example, a plurality of eight connected edge points. At this stage, even edge points with different parallaxes are grouped as the same edge group if they are adjacent.

  Then, the control unit 91a sets a rectangular area circumscribing the edge group, and divides the set rectangular area into blocks of a predetermined size. Next, the control unit 91a specifies a corresponding region corresponding to an edge region (a block including an edge point) in the reference image from a far-infrared image captured by another far-infrared imaging device B. Hereinafter, a far-infrared image captured by another far-infrared imaging device B is referred to as a reference image.

  Specifically, the control unit 91a sets a region (reference region) having the same size as the edge region in the reference image, particularly on the epipolar line, calculates a correlation value between the edge region and the reference region, and the correlation value is maximized. The point on the epipolar line is specified as the position of the corresponding region.

  Next, the control unit 91a calculates a parallax between each edge region and the corresponding region, and regroups the edge regions having substantially the same parallax difference between the edge regions, thereby setting a new edge group as an obstacle candidate region. Re-specify. By calculating the feature amount of the obstacle candidate area, it is possible to determine whether the obstacle candidate area is a pedestrian or an artificial structure, and to issue an appropriate warning.

  The first embodiment includes first to third fitting recesses 11a, 12a, and 13a that are formed so that the first to third infrared lenses 21, 22, and 23 can be shrink-fitted to the lens barrel 1. The first to third infrared lenses 21, 22, and 23 are fitted and positioned in the first to third fitting recesses 11a, 12a, and 13a, respectively, by shrink fitting. Therefore, no spacer is required, and the number of parts and the number of assembly steps can be reduced.

  The lens barrel 1 has a stepped inner peripheral surface, and the first to third infrared lenses 21, 22, and 23 are respectively fitted to the first to third fitting recesses 11a, 12a, and 13a at the shrink fitting temperature. It has a dimension to lock at the position. Accordingly, the first to third infrared lenses 21, 22, and 23 are inserted into the lens barrel 1 in order from the first infrared lens 21 having the smaller outer diameter, so that the positions of the first to third fitting recesses 11a, 12a, and 13a are set. The first to third infrared lenses 21, 22, and 23 can be fitted and positioned at a time by cooling to room temperature.

  Furthermore, the outer diameters of the first to third infrared lenses 21, 22, and 23 and the width in the optical axis L direction at room temperature are the inner diameters of the first to third fitting recesses 11a, 12a, and 13a and the width in the optical axis L direction, respectively. Since it is substantially equal to the width, the first to third infrared lenses 21, 22, and 23 can be positioned in the optical axis L direction and the radial direction.

  Furthermore, aluminum is easier to process than other metals such as brass, and the cost of the lens unit A can be reduced. In addition, since the linear expansion coefficient of aluminum is larger than that of other metals, the first to third infrared lenses 21, 22, 23 are connected to the first to third fitting recesses 11 a, 12 a at a lower shrink fitting temperature. , 13a.

  In addition, although the lens unit provided with the far-infrared lens was demonstrated, you may apply this invention to the lens unit provided with the lens which permeate | transmits visible light and near infrared rays.

  Moreover, although the example which applied the far-infrared imaging device B to the image processing system which performs driving | operation assistance of a vehicle was demonstrated, the use of an imaging device is not limited to this. For example, the present invention may be applied to a night driving support system, a tunnel monitoring, a port monitoring, a railroad track intruder monitoring, and the like.

  Furthermore, although the triplet lens unit including the first to third infrared lenses has been described, the present invention may be applied to a lens unit having two or four or more infrared lenses.

  Furthermore, the shrink-fit temperature is 200 ° C. and the room temperature after cooling is 25 ° C., but the shrink-fit temperature and room temperature are only examples, and the shrink-fit and cooling are performed in other temperature ranges. Also good.

  Furthermore, the first embodiment is configured such that the first to third infrared lenses are inserted into the lens barrel by heating, but the linear expansion coefficient of the lens barrel is the first to third. The linear expansion coefficient of the infrared lens is configured to be smaller, the lens barrel and the first to third infrared lenses are cooled, and the first to third infrared lenses are inserted into the lens barrel. good.

(Embodiment 2)
FIG. 11 is a process diagram showing an assembling method of the lens unit A according to Embodiment 2 of the present invention. The method of assembling the lens unit A according to the second embodiment is that only the lens barrel 1 is heated to the shrink fitting temperature and the first to third infrared lenses 21, 22, and 23 are inserted into the lens barrel 1. Since it is different from the method of assembling the lens unit A according to the first embodiment, the difference will be mainly described below.

  First, as in the first embodiment, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 are prepared (step S211), and the lens barrel 1 is heated to a shrink fitting temperature of 200 ° C. (step S212). ).

  Then, the first infrared lens 21 is inserted into the lens barrel 1 (step S213), the second infrared lens 22 is inserted (step S214), and the third infrared lens 23 is inserted (step S215).

  Then, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 are cooled to room temperature, for example, 25 ° C. (step S216). When cooled to room temperature, the lens barrel 1 and the first to third infrared lenses 21, 22, and 23 are thermally contracted, and the first to third infrared lenses 21, 22, and 23 are the first to third fitting recesses 11a and 12a. , 13a and is positioned.

  In the second embodiment, since only the lens barrel 1 is heated, the first to third infrared lenses 21, 22, and 23 can be fitted into the lens barrel 1 at a lower shrink fitting temperature. . Further, the first to third infrared lenses 21, 22, and 23 are easy to handle.

  Other configurations, operations, and effects of the lens unit A, the far-infrared imaging device B, the image processing system, and the manufacturing method of the lens unit A according to the second embodiment are the same as those of the lens unit A according to the first embodiment. Since the configurations, operations, and effects of the apparatus B and the image processing system are the same, the corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  It should be understood that the embodiment disclosed this time is illustrative in all respects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a sectional side view which shows typically the lens unit which concerns on Embodiment 1 of this invention. It is a graph which shows an example of the dimension of the internal peripheral surface of a 1st infrared lens and a lens-barrel. It is process drawing which shows the assembly method of the lens unit which concerns on Embodiment 1 of this invention. It is a sectional side view which shows typically the lens unit in each assembly process. It is a sectional side view which shows typically the lens unit in each assembly process. It is a sectional side view which shows typically the lens unit in each assembly process. 1 is an explanatory diagram conceptually showing an image processing system according to a first embodiment. It is a sectional side view which shows typically the structure of the far-infrared imaging device provided with the lens unit which concerns on this Embodiment 1. FIG. It is a block diagram which shows the structure of a far-infrared imaging device. It is a block diagram which shows the structure of an image processing apparatus. It is process drawing which shows the assembly method of the lens unit which concerns on Embodiment 2 of this invention. It is a sectional side view which shows the conventional lens unit typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens tube 10, 11, 12, 13 Inner peripheral surface 11a 1st fitting recessed part 12a 2nd fitting recessed part 13a 3rd fitting recessed part 21 1st infrared lens 22 2nd infrared lens 23 3rd infrared lens 7 Base 8 Case 61 Imaging unit A Lens unit B Far-infrared imaging device L Optical axis

Claims (11)

In a lens unit formed by inserting a plurality of lenses into a lens barrel,
The lens barrel is
The inner peripheral surface is provided with a plurality of fitting recesses into which the peripheral edge of each lens is fitted,
The lens barrel and lens are
When in the first temperature range, the inner diameter of the lens barrel is smaller than the outer diameter of the lens, and when in the second temperature range higher than the first temperature range, the inner diameter of the lens barrel is larger than the outer diameter of the lens. A lens unit having a linear expansion coefficient of When the lens barrel and the lens are in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of the fitting recess is smaller than the outer diameter of the lens fitted in the fitting recess, 2. The lens unit according to claim 1, wherein an inner diameter of an inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the fitting recess is larger than an outer diameter of a lens fitted in the fitting recess. In a lens unit formed by inserting a plurality of lenses into a lens barrel,
The lens barrel is
The inner peripheral surface is provided with a plurality of fitting recesses into which the peripheral edge of each lens is fitted,
The lens barrel and lens are
When in the first temperature range, the inner diameter of the lens barrel is smaller than the outer diameter of the lens, and when the lens barrel is in the second temperature range higher than the first temperature range, the inner diameter of the lens barrel is A lens unit having a linear expansion coefficient larger than an outer diameter. When the lens barrel is in the second temperature range, the inner diameter of the inner peripheral surface of the lens barrel on one end side in the optical axis direction of each fitting recess is smaller than the outer diameter of the lens fitted in the fitting recess, and the fitting The lens unit according to claim 3, wherein an inner diameter of the inner peripheral surface of the lens barrel on the other end side in the optical axis direction of the joint recess is larger than an outer diameter of the lens fitted in the fitting recess. The outer diameter of the lens and the inner diameter of the fitting recess are equal when the lens barrel and the lens are at a predetermined temperature within a first temperature range. The lens unit according to one. The widths of the peripheral edge of the lens and the fitting recess in the optical axis direction are equal when the lens barrel and the lens are at a predetermined temperature within a first temperature range. The lens unit according to any one of the above. The lens includes any one of infrared transmissive zinc sulfide, zinc selenide, germanium, chalcogenite glass, or silicon,
The lens unit according to claim 1, wherein the lens barrel is made of aluminum. The lens unit according to any one of claims 1 to 7,
An imaging apparatus comprising: an imaging unit that captures an image formed by the lens. A lens unit according to any one of claims 1 to 7 disposed in a vehicle,
An imaging unit that captures an image formed by the lens;
An image processing system comprising: an image processing unit that detects an object based on image data obtained by imaging by the imaging unit. In the manufacturing method of the lens unit formed by inserting a plurality of lenses into the lens barrel,
Prepare a plurality of lenses and a lens barrel provided with a plurality of fitting recesses on the inner peripheral surface to which the peripheral edge of each lens is fitted,
Heating the lens barrel and lens;
Inserting the lens into the barrel;
The lens barrel and the lens are cooled to a first temperature range, and the lens is fitted into the fitting recess. In the manufacturing method of the lens unit formed by inserting a plurality of lenses into the lens barrel,
Prepare a plurality of lenses and a lens barrel provided with a plurality of fitting recesses on the inner peripheral surface to which the peripheral edge of each lens is fitted,
Heating the lens barrel;
Inserting the lens into the barrel;
The lens barrel is cooled to a first temperature range, and the lens is fitted into the fitting recess.

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