JP4585259B2 - Camera barrel with focus adjustment function - Google Patents

Description

  The present invention relates to a lens barrel of a camera with a focus adjustment function.

  In recent years, camera modules as imaging means for mobile phones and small electronic still cameras have been reduced in size and price. However, the number of pixels of an image sensor such as a CCD or a CMOS image sensor is increasing, and the demand for image quality in the market is increasing. Recently, along with the increase in the number of pixels of an image sensor, a number of camera modules to which an automatic focus adjustment function has been added in order to realize a clearer and higher quality image have been announced.

  With regard to the automatic focus adjustment function, excellent mechanisms and configurations have been realized for a long time in relatively large devices such as an electronic still camera. In general, a helicoid screw is formed on a lens barrel and driven by a motor to move in the optical axis direction. The same mechanism can be adopted for a camera module mounted on a mobile phone or a small electronic still camera. However, since the size is reduced, processing and assembly become rapidly difficult. Therefore, various ingenious mechanisms have been invented so that the lens group can be moved accurately and accurately in the optical axis direction so that there is no backlash or tilt.

  As described above, it is important to move the lens group accurately and accurately in the optical axis direction so that there is no backlash or tilt. The conventional structure should be followed and the accuracy of each part should be increased, but the molding accuracy will not improve in proportion to the reduction in camera module size, so the combined result will not be satisfactory. There is. The normal dimensional accuracy of injection molding is at most about 10 to 20 micrometers for molding a small part having a size of several millimeters, and the geometric tolerance accuracy, for example, flatness is the same level.

  However, according to the results of the lens design, the concentricity of the optical axis of each lens is several micrometers or less, and the optical axis of each lens is inclined with respect to the optical axis of the imaging optical lens unit within a few minutes. I know I have to. The lens diameter of recent imaging optical lens units is getting smaller. For example, if you want to tilt the lens with a diameter of 3 mm within 7 minutes, both ends of the lens diameter have a height within 6.4 microns. I'm not allowed. This is a required value at every position where the autofocus mechanism operates.

  Many mechanisms for adjusting the focal point by moving the optical lens in the direction of the optical axis include a linear guide mechanism so that the optical lens moves accurately along the optical axis. In most cases, the moving means is separated from the linear motion guide mechanism. A typical form of the linear guide mechanism is one in which a guide hole of a holder that holds a lens is fitted to a guide shaft and is slid. In many cases, the round bar is made of metal and the holder is made of resin. The clearance with the shaft needs to be controlled to several microns or less.

  By properly managing the fitting gap, it is possible to reduce the optical axis misalignment and tilt when driving the lens, but the current state of the lens holder used in small camera modules such as mobile phones The accuracy is often insufficient. This is because the inclination of the lens increases in inverse proportion to the distance between the optical axis and the guide shaft when the gap between the guide shaft and the hole is the same. If the gap between the guide shaft and the guide hole of the holder is not reduced in proportion to the distance, the tilt of the lens will not be the same.

  This will be described with reference to FIG. FIG. 5 shows the relationship between the large guide shaft 11 that guides the lens holder large 12 that holds the lens large 13 that is an optical component, the large fitting gap 14, and the large inclination θ 15 of the lens part that is caused by the existence of the gap. FIG. FIG. 6 shows a case where the configuration of FIG. 6 is a schematic diagram showing the relationship between a small guide shaft 16 that guides a lens holder small 17 that holds a lens small 18 that is an optical component, a small fitting clearance 19, and a small inclination θ 20 of the lens component that is caused by the presence of the clearance. is there.

  When the large gap 14 and the small gap 19 are the same and the component size is halved, the guide shaft and the lens holder are loose at an angle determined by the gap width and the guide length. In this case where the large gap 14 and the small gap 19 are the same, it can be seen that the small inclination θ20 of the lens holder 17 is approximately twice the large inclination θ15.

  As means for solving such a problem, a structure in which a lens is connected to a pantograph means and moved in the direction of the optical axis has been developed. (For example, Patent Document 1, Patent Document 2, and Patent Document 3) These structures all eliminate a mechanism part and a helicoid part called a cam ring, simplify the lens barrel and reduce the size, and fold the pantograph. Realized miniaturization

Japanese Utility Model Publication No. 2-111972 Japanese Utility Model Publication No. 4-126235 JP-A-9-222550

  The invention described above, in which the lens is connected to the pantograph means and moved in the direction of the optical axis, was developed for the purpose of simplifying and downsizing the lens barrel. By using the pantograph-like motion guide means, Compared with the operation amount obtained by other means, the size can be significantly reduced. However, in both cases, the pantograph mechanism is realized by connecting the links with pins.

  In order for the link and the pin joint to operate smoothly, the link hole and the pin must always have a gap or an elastic deformation member corresponding to the gap. When the pantograph starts to expand from a structurally folded state, the ratio of output to input is extremely large, and there is a problem that a slight backlash or error becomes a large error or unscheduled displacement at the tip portion. I think that it is possible to realize a sufficiently small and accurate pan tag tough mechanism if the accuracy of the link and pin is increased, but there will be a problem that the production cost and assembly cost of the component will increase because many high-precision components will be used. .

  One or more optical lenses, an integrally molded holder for relatively positioning and fixing each of the optical lenses, and an imaging sensor for imaging the optical lens, the holder being the imaging sensor In a lens barrel of a camera with a focus adjustment function having a focus position adjustment mechanism that adjusts the focus position by moving in the optical axis direction of the optical lens with respect to the optical lens fixing for positioning and fixing the lens to the holder And an imaging sensor fixing part for positioning and fixing the imaging sensor in order from the optical lens side, a thin lens side hinge flexible for bending, a highly rigid lens side beam, and then a thin lens side flexible for bending Intermediate hinge, drive hook, imaging sensor side intermediate hinge, then high rigidity imaging sensor side beam and thin flexible imaging for bending The imaging sensor fixing unit is configured by an intermediate driving beam right composed of a hinge on the sensor side, an intermediate driving beam left in a mirror image relationship with the intermediate driving beam right, and a pantograph beam in which the intermediate driving beam right and the intermediate driving beam right are paired And a lens barrel of a camera with a focus adjustment function in which there are at least three pantograph beams.

Further, in the lens barrel of the focus adjustment function camera described above, the holder is formed of resin, containing at least one or more additives, as a first additive, diameter 80 nm or more 300 nm or less, A camera with a focus adjustment function, characterized by mixing carbon nanofibers in the form of multi-layer tubes with a length of 1 micron or more and 200 microns or less, so-called VGCF (Vapor Grown Carbon Nano-fiber). A lens barrel is used.

  Optical lens fixing part of the holder and imaging sensor fixing part are thin lens side hinges that are flexible to bend, rigid lens side beams, then thin lens side intermediate hinges that are flexible to bend, drive hooks, image sensor side intermediate It was connected by a pantograph-like beam that was paired with a hinge, then a rigid imaging sensor side beam and an intermediate driving beam right consisting of a thin imaging sensor side hinge flexible to bending, and an intermediate driving beam left in a mirror image relationship. When the drive hook in the middle of the pantograph beam is moved at right angles to the optical axis, the pantograph beam is elastically deformed by the aforementioned flexible hinge portion.

  In the conventional structure, a gap is always required between the guide shaft and the guide hole. However, in the present invention, since the elastic deformation is converted into the movement in the optical axis direction, the gap is not necessary. There will be no inconveniences such as optical axis misalignment and tilting due to. In addition, since the function constituted by a plurality of parts in the conventional structure can be realized by one part, the size can be reduced.

  In addition, since the pantograph beam realized in the present invention is formed integrally, there is a problem of accuracy due to the relationship between the link and the pin formed by a plurality of parts of the previously described pantograph means, The problem of increased costs for manufacturing and assembling a plurality of parts can be solved.

  Also, by molding the holder with resin and mixing a so-called VGCF fiber-like carbon atom structure in the form of a multilayer tube having a diameter of 80 to 300 nanometers and a length of 1 to 200 micrometers. Smaller and more precise pantograph beam can be formed. This is because the carbon nanofibers are very thin and flexible compared to the glass filler and do not hinder the flow of the resin, so that the fine structure portion of the mold can be filled. (Written by Morinobu Endo, “The depths of the field, the tip of science.” Bunya 2004)

  One or more optical lenses, an integrally molded holder for relatively positioning and fixing each of the optical lenses, and an imaging sensor for imaging the optical lens, the holder being the imaging sensor In a lens barrel of a camera with a focus adjustment function having a focus position adjustment mechanism for adjusting a focus position by moving in the optical axis direction of the optical lens, an optical lens fixing portion for positioning and fixing the lens to the holder And an imaging sensor fixing portion for positioning and fixing the imaging sensor in order from the optical lens side, a thin lens side hinge that is flexible for bending, a highly rigid lens side beam, and then a thin lens side middle that is flexible for bending. Hinge, drive hook, intermediate hinge on the image sensor side, then a rigid image sensor side beam and a thin and flexible image sensor The imaging sensor fixing unit is configured by an intermediate drive beam right comprising a circadian hinge, an intermediate drive beam left mirror-imaged with the intermediate drive beam right, and a pantograph-like beam paired with the intermediate drive beam right and the intermediate drive beam right And the pantograph beam is at least three or more, the holder is formed of a resin, the resin contains at least one additive, the first additive, The lens barrel of the camera with a focus adjustment function is a multilayer tube shape having a diameter of 80 to 300 nanometers and a length of 1 to 200 micrometers.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a lens barrel of a camera with a focus adjustment function showing the best mode of the present invention, in which only one pantograph beam is shown and the rest is omitted. FIG. 2 is an operation diagram in which only one pantograph-like beam of the present invention is taken out and only the fundamental elements are represented. FIG. 3 is a developed view in which three pairs of principle diagrams of the pantograph beam shown in FIG. 2 are arranged, and FIG. 4 is a detailed view on the left of the intermediate drive beam.

  In FIG. 1, 1 is an optical lens, 2 is an optical lens fixing unit, 3 is an imaging sensor, 4 is an imaging sensor fixing unit, 5 is an intermediate driving beam right, 6 is an intermediate driving beam left, and these are considered as a pair. This is a pantograph beam 7.

  In FIG. 2, the hinge portion is illustrated as a black fulcrum as a rotation fulcrum (lens side hinge 8-1, intermediate hinge 8-2, imaging side hinge 8-3), and the rigid lens side beam and imaging sensor side beam. Are indicated by lines as link L9-1 and link S9-2, respectively. Drive hooks (described in FIG. 4) are grouped together in an intermediate hinge 8-2.

  A portion indicated by a dotted line in FIG. 2 shows an initial state of the pantograph beam. When the drive hook is expanded to the left and right by the movement amount I from this initial state, the rhombus of the pantograph-like beam spreads in the horizontal direction in the figure, and the distance between the image sensor fixing unit 4 side and the lens fixing unit 2 side is the movement amount O. Will only shrink.

  FIG. 3 shows three pairs of the principle diagrams of the pantograph beam shown in FIG. 2, and is a schematic representation of the lens barrel of the present invention developed on a plane. Three pairs of pantograph-like beams 7 have the same shape, connect the imaging sensor fixing part 4 and the optical lens fixing part 2, and the drive hooks are moved at the same timing, so that the rhombus of the pantograph-like beam 7 changes to the same shape at the same timing. The image sensor fixing unit 4 and the optical lens fixing unit 2 supported by three points can move along the optical axis while maintaining parallelism.

  FIG. 4 is a diagram showing details of the left intermediate drive beam, 8-1 is a lens side hinge, 9-1 is a lens side beam, 8-2-1 is a lens side intermediate hinge, 10 is a drive hook, 2-2 is an image sensor side intermediate hinge, 9-2 is an image sensor side beam, and 8-3 is an image sensor side hinge. These series of objects are collectively referred to as an intermediate drive beam left 6. Similarly, a series of objects having a mirror image relationship with the intermediate drive beam left 6 is collectively referred to as an intermediate drive beam right 5. The intermediate drive beam right 5 and the intermediate drive beam left 6 are referred to as a pantograph beam 7 as a pair.

  Each hinge portion in FIG. 4 is made thin so that it can be repeatedly bent without breaking within a certain angle range. Since each beam is thick and rigid, it hardly bends. Here, when the pair of drive hooks 10 are slightly expanded to the left and right, the hinges are deformed to bend, and the angles formed by the beams and the fixing portions are changed. The intermediate drive beam right 5 and the intermediate drive beam left 6 in FIG. 4 are connected to the optical lens fixing unit 2 and the image sensor fixing unit 4 almost at the same place by a lens side hinge 8-1 and an image sensor side hinge 8-3. Therefore, it moves almost the same as the link mechanism shown in FIG.

  If the drive hooks 10 of the three pairs of pantograph beams as shown in FIG. 3 are connected to the intermediate drive beam right 5 and the intermediate drive beam left 6 with a rigid ring or the like, respectively, and driven in the opposite direction, The three pairs of pantograph beams simultaneously perform the same operation at the same timing, and the optical lens fixing unit 2 and the image sensor fixing unit 4 can move along the optical axis while maintaining parallelism.

  In the best mode of the present invention, the lens barrel can be integrally formed of resin, which is advantageous for downsizing and at the same time cost. Recently, many studies and inventions have been made that can improve the quality of molded products by mixing carbon nanofibers with resin. Carbon nanofibers are high aspect ratio carbon fibers having a diameter of submicrometers and a length of several tens of micrometers. It has been confirmed that carbon nanofibers are not only thin and long, but also have high strength, have extremely high cutting resistance against bending, and do not break or cut even when bent at an acute angle.

  In addition, it is known that it has a thermal conductivity as high as that of metal. It is also thermally stable and does not denature at all in the temperature range used for resin molding. Furthermore, since it is composed of almost pure carbon atoms, it does not contaminate the resin or cause chemical changes. Moreover, since it has a structure similar to graphite, it has high lubricity. Utilizing these properties, it is expected to be used as an additive to resin molding materials.

  Furthermore, when carbon nanofibers are mixed with the resin, the carbon nanofibers have a very small fiber diameter and are flexible as compared with the glass filler, and thus do not impair the fluidity of the added resin. Therefore, if it is used as a molding material for the lens barrel, the fine structure portion of the mold can be filled, and each of the hinge portions can be molded more thinly and accurately. Moreover, when it shape | molds with the material which mixed the carbon nanofiber, there also exists an effect that the shape precision of a molded article improves.

  Regarding the mechanical properties of the resin molded with carbon nanofibers, a paper submitted to the Japan Society of Mechanical Engineers "Evaluation of mechanical properties of carbon nanofiber reinforced plastics" (Japan Opportunity Society (No03-11)) Shinshu University's report by Arai and Sugimoto et al. On the presentation of the lectures on materials mechanics section describes the relationship between the mixing ratio of various resins and carbon nanofibers and the mechanical properties. For example, when VGCF is mixed with PP (polypropylene), an improvement in Young's modulus is observed according to the weight% as shown in FIG. When 10% by weight is mixed, the Young's modulus is improved by about 30%, and when 40% is mixed, the rigidity is increased by about twice that of pure PP. It is known from many other studies that stiffness is improved in most resins, albeit to varying degrees.

  As described above, the resin material mixed with carbon nanofibers has the excellent properties of high molding accuracy and improved mechanical rigidity as described above, and is optimal for constituting the lens barrel of the present invention.

Schematic diagram showing a lens barrel of a camera with a focus adjustment function showing the best mode of the present invention Operation diagram showing only the basic elements of one pantograph beam of the present invention A developed view of three pairs of principle diagrams of the pantograph beam in FIG. Detailed view of the left intermediate drive beam Schematic representation of the fit gap Schematic illustration of fitting gap

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical lens 2 Optical lens fixing | fixed part 3 Imaging sensor 4 Imaging sensor fixing | fixed part 5 Middle drive beam right 6 Middle drive beam left 7 Pantograph beam 8-1 Lens side hinge 8-2 Intermediate hinge 8-2-1 Lens side intermediate hinge 8-2-2 Imaging sensor side intermediate hinge 8-3 Imaging side hinge 9-1 Link L
9-2 Link S
10 Driving hook 11 Large guide shaft 12 Large lens holder 13 Large lens 14 Large gap 15 Large tilt θ
16 Small guide shaft 17 Small lens holder 18 Small lens 19 Small gap 20 Small tilt θ

Claims (2)

  One or more optical lenses, an integrally molded holder for relatively positioning and fixing each of the optical lenses, and an imaging sensor for imaging the optical lens, the holder being the imaging sensor In a lens barrel of a camera with a focus adjustment function having a focus position adjustment mechanism for adjusting a focus position by moving in the optical axis direction of the optical lens, an optical lens fixing portion for positioning and fixing the lens to the holder And an imaging sensor fixing portion for positioning and fixing the imaging sensor in order from the optical lens side, a thin lens side hinge that is flexible for bending, a highly rigid lens side beam, and then a thin lens side middle that is flexible for bending. Hinge, drive hook, intermediate hinge on the image sensor side, then a rigid image sensor side beam and a thin and flexible image sensor The imaging sensor fixing unit is configured by an intermediate drive beam right comprising a circadian hinge, an intermediate drive beam left mirror-imaged with the intermediate drive beam right, and a pantograph-like beam paired with the intermediate drive beam right and the intermediate drive beam right And at least three of the pantograph-like beams. 2. The lens barrel of the camera with a focus adjustment function according to claim 1, wherein the holder is molded of a resin and contains at least one additive, and the first additive has a diameter of 80 nanometers or more and 300 nanometers or less. A lens barrel for a camera with a focus adjustment function, characterized in that it is a carbon nanofiber in the form of a multilayer tube having a length of 1 micrometer or more and 200 micrometers or less.

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