JP5146319B2 - Lens barrel - Google Patents

Description

  The present invention relates to an imaging lens barrel, and more particularly to an in-vehicle lens barrel that is suitable for use in an environment that directly touches the outside air and has a large temperature and humidity change.

Imaging devices such as digital cameras and shooting in rainy weather are often protected and protected by a cover or cover, so the lens barrel that holds the lens usually does not take environmental performance into consideration. Few. Therefore, the lens barrel is composed of one type of material that takes moisture absorption characteristics into consideration (see Patent Document 1).
JP 2005-274633 A

  By the way, in recent years, in order to support the operation of the driver, a camera or the like that displays an image of the rear side or the passenger seat side is mounted on the vehicle. Here, the vehicle-mounted camera is placed in a harsh environment where it is always exposed to the sun's ultraviolet rays, rainfall, snowfall, snow melting agent, and the like. Therefore, it is conceivable that the lens barrel exposed to the outside world is constituted by using, for example, PPA (polyphthalamide), which is a “crystalline plastic” having excellent environmental performance. However, since PPA has a relatively high hygroscopicity, when used as a lens barrel, even if it is accurately adjusted during assembly, swelling deformation occurs when used in a high humidity environment, and the lens that it holds There is a risk that the optical characteristics will be deteriorated.

  The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide a lens barrel capable of maintaining good optical characteristics while maintaining environmental performance.

The lens barrel of the present invention is a lens barrel that holds a plurality of lenses, and includes an outer frame member that supports at least a first lens group having a first lens closest to the subject, and the outer frame member. An inner frame member that supports a second lens group disposed behind the first lens group, and the first resin material forming the outer frame member is crystalline plastic, and the inner frame member is the second resin material for forming is characterized noncrystalline (or amorphous) plastic der Rukoto.

According to the present invention, in a first crystalline plastic der Rukoto the resin material Ru comprises a pair environmental performance that constitutes the outer frame member which is exposed to the outside, can secure the durability by suppressing the influence from the outside , and in the second low resin material hygroscopicity noncrystalline (or amorphous) plastic der Rukoto constituting the inner frame member that holds the second lens group to suppress the deformation of the inner frame member Thus, the backlash of each lens constituting the second lens group can be suppressed.

Incidentally, the first resin material is excellent environmental performance compared with the second resin material. Here, “environmental performance” means at least one of chemical resistance, high strength, and heat resistance.

  The outer frame member and the inner frame member are preferably connected by screw connection.

  It is preferable that the first lens is made of glass because it is superior in environmental performance as compared to a resin lens, so that the performance can be maintained even when exposed to the outside.

  If the linear expansion coefficient of the material of the lens constituting the second lens group is equal to the linear expansion coefficient of the second resin material, it is preferable that rattling does not occur even if a temperature change occurs.

  According to the present invention, it is possible to provide a lens barrel capable of maintaining good optical characteristics while maintaining environmental performance.

1 is a block diagram of an imaging apparatus 100. FIG. 1 is a cross-sectional view of an optical system 101. FIG. It is sectional drawing of the optical system 101 concerning a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lens barrel 11 Outer frame member 11a Inner peripheral step part 11b Inner peripheral guide part 11c Female thread part 12 Inner frame member 12a First inner peripheral step part 12b Second inner peripheral step part 12b Male screw part 12c Outer peripheral guide part 12e In third Peripheral unit 100 Imaging device 101 Optical system 102 Solid-state imaging device 103 Conversion unit 104 Control unit 106 Timing generation unit 107 Imaging device driving unit 108 Image memory 109 Image processing unit 110 Image compression unit 111 Image recording unit 112 Display unit 113 Operation unit L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens LS Lens part

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. With reference to FIG.1 and FIG.2, the imaging device 100 carrying the lens barrel concerning embodiment of this invention is demonstrated. FIG. 1 is a block diagram of the imaging apparatus 100. Note that the imaging apparatus 100 can be mounted on a vehicle in a form in which at least the optical system 101 is exposed to the outside.

  As illustrated in FIG. 1, the imaging apparatus 100 includes an optical system 101, a solid-state imaging device 102, an A / D conversion unit 103, a control unit 104, a timing generation unit 106, an imaging device driving unit 107, and an image. A memory 108, an image processing unit 109, an image compression unit 110, an image recording unit 111, a display unit 112 that is a display in a vehicle interior, and an operation unit 113 are configured.

  The optical system 101 has a function of forming a subject image on the imaging surface of the solid-state imaging device 102. The solid-state image sensor 102 is an image sensor such as a CCD or CMOS, and photoelectrically converts incident light for each of R, G, and B and outputs an analog signal thereof. The A / D conversion unit 103 converts an analog signal into digital image data.

  The control unit 104 controls each unit of the imaging device 100. The control unit 104 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and various programs read out from the ROM and expanded in the RAM, and various in cooperation with the CPU. Execute the process.

  The timing generator 106 outputs a timing signal for analog signal output. The image sensor drive unit 107 performs scanning drive control of the solid-state image sensor 102.

  The image memory 108 stores image data so as to be readable and writable. The image processing unit 109 performs various image processes on the image data. The image compression unit 110 compresses captured image data by a compression method such as JPEG (Joint Photographic Experts Group). The image recording unit 111 records image data on a recording medium such as a hard disk or a memory card set in a slot (not shown).

  The display unit 112 is a color liquid crystal panel or the like, and can display image data after shooting, a through image before shooting, various operation screens, and the like. The operation unit 113 includes various operation keys for setting values, and outputs information input by the driver to the control unit 104.

  Here, the operation of the imaging apparatus 100 will be described. Here, a case where monitoring (through image display) of a subject on the rear side of the vehicle is performed will be described. For example, when the back gear is selected for the vehicle equipped with the image pickup apparatus 100 to move backward, the solid-state image sensor 102 is scanned and driven by the timing generation unit 106 and the image sensor drive unit 107, and the solid-state image sensor 102 is connected via the optical system 101. The object image on the rear side of the vehicle imaged on the light receiving surface of the vehicle is photoelectrically converted, and an analog signal as an output is output for one screen every fixed period.

  The analog signal is appropriately gain-adjusted for each primary color component of RGB, and then converted into digital data by the A / D conversion unit 103. The digital data is subjected to color process processing including pixel interpolation processing and γ correction processing by the image processing unit 109 to generate a luminance signal Y and color difference signals Cb, Cr (image data) as digital values, and the image memory. The video signal is periodically read out and the video signal is generated and output to the display unit 112 so that it can be visually recognized by the driver.

  The display unit 112 functions as an electronic viewfinder in monitoring, and displays captured images in real time.

  In such a monitoring state, still image data can also be obtained by the driver operating the button of the operation unit 113 or at the command of the in-vehicle computer at a timing when still image shooting is desired. In response to this, one frame of image data stored in the image memory 108 is read out and compressed by the image compression unit 110. The compressed image data is recorded on a recording medium by the image recording unit 111.

  FIG. 2 is a cross-sectional view showing an example of the optical system 101 according to the present embodiment, and the lower half is omitted. The optical system 101 includes a lens unit LS and a lens barrel 10. The lens unit LS is arranged in the order of the negative first lens L1, the negative second lens L2, the diaphragm S, and the positive third lens L3 from the subject side (left side in FIG. 2), but other combinations are possible. You can also. As a general on-vehicle optical system, it is preferable to use a wide-angle lens having a focal length of 38 mm or less in terms of 35 mm film.

  The lens barrel 10 includes a hollow cylindrical outer frame member 11 and an inner frame member 12. The cylindrical outer frame member 11 is fixed to the inner peripheral step portion 11a on the subject side by caulking and fixing the flange portion of the first lens L1 closest to the subject side while being positioned in the optical axis direction and the optical axis orthogonal direction (even by bonding). Good). The first lens L1 is made of glass. The outer frame member 11 has an inner peripheral guide portion 11b and a female screw portion 11c having a larger diameter on the inner periphery thereof. In the present embodiment, the first resin material forming the outer frame member 11 is PPA (polyphthalamide), which is a “crystalline plastic” that is excellent in chemical resistance, high strength, and heat resistance, which is environmental performance. ) Is used. In this example, the first lens L1 corresponds to the first lens group.

  The cylindrical inner frame member 12 includes a first inner peripheral step portion 12a on the subject side and a second inner peripheral step portion 12b on the imaging element side having a smaller diameter. At the time of assembly, first, the flange portion of the third lens L3 inserted from the subject side is caulked and fixed (adhesion may be performed) in a state of abutting against the second inner circumferential step portion 12b, and further, the first inner circumferential step from the subject side. The outer periphery of the diaphragm S is inserted into and abutted on the portion 12a, and the flange portion of the second lens L2 is abutted thereon and fixed by caulking (adhesion may be used). Accordingly, the second lens L2 and the third lens L3 are positioned with respect to the inner frame member 12 in the optical axis direction and the optical axis orthogonal direction. In the present embodiment, PC (polycarbonate), which is “amorphous (or amorphous) plastic” having low hygroscopicity, is used as the second resin material forming the inner frame member 12. In this example, the second lens L2 and the third lens L3 correspond to the second lens group.

  Further, the inner frame member 12 has an outer peripheral guide portion 12c that engages with the inner peripheral guide portion 11b of the outer frame member 11, and a male screw portion 12d that engages with the female screw portion 11c. By fitting the inner peripheral guide portion 11b and the outer peripheral guide portion 12c, the outer frame member 11 and the inner frame member 12 are positioned in the direction perpendicular to the optical axis. Further, the distance between the first lens L1 and the second lens L2 is adjusted by changing the screwing amount of the female screw portion 11c and the male screw portion 12d, and the light receiving surface of the solid-state imaging device 102 is in focus. An image can be formed.

  According to the present embodiment, since the outer frame member 11 is made of PPA having excellent environmental performance with respect to the PC, the outer frame member 11 is exposed to the sun's ultraviolet rays, rainfall, snowfall, snow melting agent, etc. while being exposed outside the vehicle. Even if it is done, an internal lens part can be protected over a long period of time. In addition, since the first lens L1 located closest to the subject side is made of glass, there is an advantage that it is not easily damaged and has excellent weather resistance.

On the other hand, the inner frame member 12 that supports the second lens L2 and the third lens L3 is used in a high humidity state by using a PC having low hygroscopicity but poor environmental performance with respect to PPA. Even in this case, the deformation of the inner frame member 12 can be suppressed and the occurrence of backlash in the second lens L2 and the third lens L3 can be suppressed. In addition, since the second lens L2 and the third lens L3 are formed of the same material as the inner frame member 12, the linear expansion coefficient becomes equal, so that even when a temperature change occurs, the amount of deformation can be made equal. Generation of play of L2 and the third lens L3 can be suppressed.
The first resin material forming the outer frame member 11 is not limited to the above PPA, but may be PA-MXD6 (polyamide MXD6), which is a “crystalline plastic”. Further, the second resin material forming the inner frame member 12 is not limited to the above-described PC, but may be PAR (polyarylate) which is “amorphous (or amorphous) plastic”.

  As a combination of the first resin material forming the outer frame member 11 and the second resin material forming the inner frame member 12, for example, the outer frame member 11 is a combination of PPA, the inner frame member 12 is a PC, and the outer frame PPA for member 11, PAR for inner frame member 12, PA-MXD6 for outer frame member 11, PC for inner frame member 12, PA-MXD6 for outer frame member 11, PAR combination for inner frame member 12, etc. Is applicable.

  In addition, although the outer frame member 11 and the inner frame member 12 are couple | bonded by screwing of a thread part, it can also couple | bond not only by this but by adhesion | attachment or laser welding. Further, although the optical system of the single focus lens has been described here, the inner frame member may be movable with respect to the outer frame member, and a focusing lens or a zoom lens may be configured.

FIG. 3 is a cross-sectional view of the optical system 101 according to the modification, and the lower half is omitted. In this modification, the lens unit LS includes a negative first lens L1 (corresponding to the first lens group) from the subject side (left side in FIG. 3), a negative second lens L2, a positive third lens L3, and a diaphragm S. The negative fourth lens L4 (corresponding to the second lens group) is arranged in this order. In addition, the inner frame member 12 forms a first inner circumferential step 12a, a second inner circumferential step 12b, and a third inner circumferential step 12e, which gradually become smaller in diameter from the subject side. At the time of assembly, first, the flange portion of the fourth lens L4 inserted from the subject side is caulked and fixed (adhesion may be performed) in a state of being abutted against the third inner peripheral step portion 12e, and then the second inner periphery from the subject side. The outer periphery of the aperture stop S is inserted into the step 12b and abutted caulking and fixed (may be bonded), and the second lens L2 is inserted into the first inner peripheral step 12a from the subject side and abutted against each other. The part is fixed by caulking (adhesion may be used). As a result, the second lens L2, the third lens L3, the stop S, and the fourth lens L4 are positioned in the optical axis direction with respect to the inner frame member 12. Since other configurations are the same as those in the above-described embodiment, the description thereof is omitted.
In the above embodiment, the first lens group supported by the outer frame member 11 is composed of one lens, and the second lens group supported by the inner frame member 12 is composed of a plurality of lenses. As described above, the first lens group is composed of a plurality of lenses, the second lens group is composed of a single lens, and the first lens group and the second lens group are each composed of a plurality of lenses. It may be a thing. In other words, the outer frame member 11 and the inner frame member 12 only need to support at least one lens. Moreover, when the 1st lens group supported by the outer frame member 11 is comprised with multiple pieces, it is preferable that the 1st lens L1 arrange | positioned at the to-be-photographed object side is glass.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, in the above-described embodiment, the lens barrel used in the in-vehicle image pickup apparatus has been described as an example. However, the present invention is not limited to this, and the present invention can also be used in an image pickup apparatus for a monitoring camera or a mobile phone.

Claims (4)

In a lens barrel that holds a plurality of lenses,
An outer frame member supporting at least a first lens group having a first lens closest to the subject;
An inner frame member included in the outer frame member and supporting a second lens group disposed behind the first lens group;
First resin material that forms the outer frame member is a crystalline plastic, a second resin material forming the inner frame member is a non-crystalline (or amorphous), wherein plastic der Rukoto Lens barrel. The lens barrel according to claim 1 , wherein the outer frame member and the inner frame member are coupled by screw connection. The lens barrel according to claim 1 or 2, wherein the first lens is characterized in that is made of glass. The lens barrel according to any one of claims 1 to 3 , wherein a linear expansion coefficient of a material of a lens constituting the second lens group is equal to a linear expansion coefficient of the second resin material. .