JP7532011B2 - Manufacturing method of optical components, optical equipment - Google Patents

Description

The present invention relates to a method for manufacturing an optical component having a sliding portion that comes into contact with another member, and to an optical device.

Conventionally, for optical products (optical components) used in optical devices such as cameras, particularly large telephoto lenses with long focal lengths, there has been a strong demand for lighter and more compact lens barrels for portability and maneuverability during shooting. As a result, there has been a trend toward using resin and thinning the parts that make up the barrel that holds the lens.

Conventionally, in order to reduce the size and weight of parts that make up various industrial products, a method has been known in which all or part of a part that was previously made of metal is changed to resin, which has a lighter specific gravity. In such cases, consideration may also be given to reducing the dimensions, particularly the thickness, of the metal and resin parts at the same time. For example, Patent Document 1 below discloses a structure in which metal and resin parts are integrated through integral molding, taking into consideration the rigidity, strength, and weight reduction of the lens barrel. In addition, for optical lens barrels, Patent Document 2 below proposes a tube part with a protruding part with a mesh structure that is lightweight and difficult to deform.

JP 2003-167180 A JP 2004-4269 A

For example, a telephoto lens equipped with a lens with a long focal length and large aperture, such as one with a focal length of over 500 mm to 1000 mm, can have a total weight on the order of kilograms. Such optical products exist, for example, as interchangeable lenses for mirror-type or mirrorless single-lens reflex cameras. It is ideal for such optical products to be as lightweight as possible to facilitate portability and handling. However, in optical products such as this type of interchangeable lens, the optical elements and mechanical parts themselves are large and heavy, so from the standpoint of strength and wear resistance of sliding parts, it may be difficult to simply replace the housing parts of the lens barrel from metal to resin.

In addition, generally, in a lens barrel, a structure may be required to form a V-shaped groove called a light shielding line on the inner surface of the housing part in a portion where ghosts or flares due to stray light occur. When performing such groove processing, it may be difficult to make the resin part thin. In addition, in an optical product such as a lens barrel, strict light shielding is required between the housing and the space around the internal optical axis to prevent disturbance light from being irradiated into the lens. Therefore, the main parts of the housing parts of the lens barrel must have the necessary light shielding properties. For example, for optical parts such as the guide tube and cam tube that make up the lens barrel, it is practically impossible to adopt a structure that includes an opening that penetrates from the inside to the outside in order to reduce weight.

In view of the above problems, the object of the present invention is to provide a small, lightweight optical component with the necessary strength and wear resistance, or an optical device equipped with such an optical component.

A first aspect of the present invention is a method for manufacturing an optical component, comprising: a step of performing build-up molding on a base portion having a portion made of a first metallic material using a second metallic material having a different main component from the first metallic material; and a step of forming a through hole in the base portion so as to remove a third portion of the second portion, a fourth portion of the second metallic material covering the third portion of the second metallic material, and the third portion of the base portion, while leaving a first portion of the base portion made of the first metallic material, a first portion of the second portion of the base portion covered with the second metallic material, and a second portion of the second metallic material covering the first portion, wherein the first portion and the third portion are not covered with the second metallic material in the direction in which the third portion and the fourth portion are arranged, the first portion is continuous with the first portion, and the second portion is continuous with the fourth portion.

With the above configuration, the present invention can provide a small, lightweight optical component or an optical product equipped with the optical component that has the necessary strength and wear resistance.

FIG. 2 is an external perspective view of a housing part of the lens barrel according to the first embodiment of the present invention. 1 is an explanatory diagram showing a configuration of a camera according to a first embodiment of the present invention. 1A is an external perspective view showing the assembled structure of the housing parts of the lens barrel according to the first embodiment of the present invention, particularly the metal parts of the focus unit, and FIG. 1B is a cross-sectional view showing the structure of the focus unit including a focus lens. FIG. 4 is an exploded perspective view showing the structure of the focus unit of FIG. 3 . 1 is an external perspective view showing a housing part of a lens barrel according to a first embodiment of the present invention, in particular a part formed in a first process including an inner light-shielding portion of a guide barrel. FIG. 1 is an external perspective view showing the housing parts of the lens barrel according to the first embodiment of the present invention, in particular the skeletal structure and sliding parts of the guide barrel, which are formed from different metal materials in a second process. FIG. 1A to 1C are explanatory diagrams showing a method for manufacturing a housing part of the lens barrel according to the first embodiment of the present invention, in particular a guide barrel, using a 3D printer. 1A and 1B are cross-sectional views showing a manufacturing method for the housing parts of the telescope barrel according to the first embodiment of the present invention, particularly the third step of removing unnecessary portions of the guide tube, where FIG. 1A shows the state before the third step and FIG. 1B shows the state after the third step. FIG. 11 is an external perspective view of a housing part of a lens barrel according to a second embodiment of the present invention. 13 is an external perspective view showing a housing part of a lens barrel according to a second embodiment of the present invention, in particular a base material required in a second step formed in a first step of a cam barrel. FIG. 13 is an external perspective view showing the housing parts of the lens barrel according to the second embodiment of the present invention, in particular the skeletal structure and sliding parts of the cam barrel, which are formed from different metal materials in a second process. FIG. 10A to 10C are explanatory diagrams showing a manufacturing method for a housing part of a lens barrel according to a second embodiment of the present invention, in particular a cam barrel, using a 3D printer. 10A and 10B are cross-sectional views showing a manufacturing method for the third step of removing unnecessary portions of the housing parts of the lens barrel of embodiment 2 of the present invention, particularly the cam barrel, where (A) shows the state before the third step and (B) shows the state after the third step. 1 is a table showing the material, specific gravity, volume, and weight of an optical component manufactured according to the first embodiment of the present invention. FIG. 11 is a table showing the material, specific gravity, volume, and weight of an optical component manufactured according to the second embodiment of the present invention. FIG. 11 is an explanatory diagram showing a configuration of a camera according to a third embodiment of the present invention. FIG. 11 is an external perspective view of a housing part of a quick-return mirror according to a third embodiment of the present invention. FIG. 11 is an external perspective view showing the shape of the housing parts of the quick-return mirror according to the third embodiment of the present invention, particularly the shape of the primary mirror holder formed in a first step. FIG. 13 is an external perspective view showing a housing part of a quick-return mirror according to embodiment 3 of the present invention, in particular a sliding part of a primary mirror holder, which is formed in a second process from a metal material different from that of the other parts, and is an explanatory diagram showing a manufacturing method using a 3D printer. FIG. 11 is a table showing the material, specific gravity, volume, and weight of an optical component manufactured according to the third embodiment of the present invention. 13 is a graph showing the oscillation characteristics of a quick return mirror according to the third embodiment of the present invention.

Below, a description will be given of an embodiment of the present invention with reference to the attached drawings. Note that the configuration shown below is merely an example, and those skilled in the art can appropriately change the detailed configuration, for example, without departing from the spirit of the present invention. Also, the numerical values used in this embodiment are for reference only and do not limit the present invention.

<Embodiment 1>
In this embodiment, an optical component including an inner surface light-shielding portion made of a first metal material having a low specific gravity, and a skeletal structure and a sliding portion made of a different second metal material having a predetermined strength and abrasion resistance that is bonded to the inner surface light-shielding portion, and a method for manufacturing the optical component will be described. In the following embodiment, a lens barrel component will be shown as an example of the optical component.

In this embodiment, the inner light-shielding portion of the optical component is formed during the process of extrusion molding or casting (e.g., die casting), or by further cutting or pressing after casting. The portion where the inner light-shielding portion is formed constitutes part of the function of maintaining the rigidity or strength of the optical component, and also functions as a portion for imparting optical properties such as light-shielding and anti-reflection properties. Of these, light-shielding properties are imparted by using a metal, which is an opaque material. Anti-reflection properties are imparted by forming light-shielding lines (light-shielding grooves) through post-processing, or by forming anti-reflection surface treatments such as electrostatic flocking or matte coating in the required areas.

On the other hand, the skeletal structure and sliding parts of the optical component are formed on the inner light-shielding part by 3D printing different metal materials using a powder supply method, and precision and surface properties are imparted by cutting after 3D printing. The skeletal structure mainly maintains the rigidity and strength of the optical component, and the sliding parts mainly maintain the wear resistance of the optical component. Note that a mesh-like skeleton is formed in the skeletal structure by the above-mentioned 3D printing. This reduces the volume of the skeletal structure, making it possible to reduce the weight of the optical component. Note that in the following embodiments, the inner light-shielding part and the skeletal structure may be referred to as the base material part.

In this embodiment, the optical component is a lens barrel component (lens barrel housing component). The inner light-shielding portion of the lens barrel component in this embodiment is made of a metal with a close or high melting point, with a skeletal structure and sliding parts that can be subsequently laminated using a 3D printer.

On the other hand, the skeletal structure, which leaves areas requiring rigidity including screw fastening parts to reduce weight while maintaining strength, is made from a first metal material with a lower specific gravity than the sliding parts. The sliding parts and joints with other parts, which require wear resistance, are made from a second metal material that is more wear resistant than the skeletal structure. In the second step of the manufacturing method of this embodiment, the skeletal structure and sliding parts are formed from different materials by 3D printing using a powder supply method.

Specifically, the optical component of this embodiment is a lens barrel part that constitutes the lens barrel of an optical lens barrel. The lens barrel part of this embodiment is the inner tube (guide tube) of the focus unit that movably supports the optical element, particularly the focusing lens, within the lens barrel. In this inner tube (guide tube), sliding parts such as the linear cam part of the focus unit and the vicinity of the fitting part that slides with the cam tube are made of a metal with high wear resistance. These sliding parts may be surface-treated to improve wear resistance.

The other parts are made of metal with a lower specific gravity than highly wear-resistant metals, and are hollowed out to the extent that strength is not lost as a skeletal structure. The inner tube (guide tube) must have a circumferential surface with light-shielding optical properties to prevent external light from entering the shooting (observation) optical path. The inner surface of the inner tube (guide tube) is made an anti-reflective surface by forming a light-shielding line (light-shielding groove) on the inner surface or by applying a surface treatment such as electrostatic flocking or matte painting to prevent light from reflecting in the optical properties and causing ghosts and flares. With regard to this anti-reflective surface, surface treatments such as electrostatic flocking or matte painting allow the metal to be thinner than light-shielding lines, which allows the thickness of the telescope tube parts to be thinner and may lead to further weight reduction.

Figure 2 shows the configuration of a single-lens reflex digital camera as an optical device that can use the lens barrel component of this embodiment. In Figure 2, a camera body 2 is connected to a photographing lens 1. Light from a subject is photographed through optical lenses such as lens 3 included in the photographing lens 1. Before shooting, the light is reflected by a main mirror 7, passes through a prism 11, and then the photographed image is displayed to the photographer through a viewfinder lens 12. In addition, the main mirror 7 is a half mirror, and the light that passes through the main mirror is reflected by a sub-mirror 8 in the direction of an AF (autofocus) unit 13, and this reflected light is used for distance measurement, for example.

When taking a photograph, the main mirror 7 and sub-mirror 8 are moved out of the optical path via a drive mechanism (not shown), the shutter 9 is opened, and the photographic light image incident from the photographic lens 1 is formed on the image sensor 10. The aperture 6 is used to change the brightness and focal depth during photography by changing the opening area. Even if silver halide film is used instead of the image sensor 10 of the single-lens reflex camera of FIG. 2, the lens barrel components of this embodiment can be configured in a similar manner to that described below. The photographic lens 1 may be fixedly attached to the camera body 2, but in many cases in this type of optical device, the photographic lens 1 is configured as an interchangeable lens that can be attached and detached to the body of the camera body 2.

The photographic lens 1 is configured so that the focus state can be adjusted by variably moving the position of the focus lens 5 inside the focus unit 4 in the optical axis direction. Note that the lens barrel parts of this embodiment constitute the focus unit 4 that adjusts the focal length, but the configuration of the same lens barrel parts can also be applied to a zoom unit that variably adjusts the magnification. An example of the configuration of the focus unit 4 of this embodiment is shown in Figures 3(A), (B), and 4.

As shown in Figures 3(A), (B) and 4, the focus unit 4 of this embodiment includes a cam barrel 14, which is an outer barrel, and a guide barrel 15, which is an inner barrel that corresponds to the lens barrel component of this embodiment. The cam barrel 14 and the guide barrel 15 each include a diagonal cam and a rectilinear cam, and are configured to move the focus lens 5 forward or backward on the optical axis within the unit. The cam barrel 14 is coupled to a focus ring (not shown) of the photographic lens 1 that can be rotated by the photographer. This allows the photographer to adjust the focus by operating the focus ring while observing the focus state through, for example, the viewfinder lens 12 (Figure 2).

The cam barrel 14 has diagonal cams 17 arranged, for example, at 120° intervals on its circumference, while the guide barrel 15 has linear cams 18 arranged at 120° intervals. The focus lens 5 is fixed to the guide barrel 15 on the inner barrel side by a focus lens holder 16. Bearings 19 are attached to the focus lens holder 16, for example, at 120° intervals.

The bearing 19 engages with the diagonal cam 17 and the linear cam 18 and is fixed in position. The inner surface of the cam barrel 14 engages with the sliding parts 24, 25 (Figure 8) of the guide barrel 15. In addition, the guide barrel 15 has a bearing 22 screwed into a screw fastening hole 23, and the bearing 22 also engages with the cam barrel 14.

As shown in Figure 4, the charge barrel 20 urges the cam barrel 14 in the optical axis direction by the washer spring 21 in contact with the guide barrel 15. As a result, the cam barrel 14 is urged diagonally downward and to the right in Figure 3 by the bearing 22 and the charge barrel 20, and the position of the focus lens 5 in the optical axis direction is maintained. The guide barrel 15 is fastened to an outer barrel part of the focus unit 4, such as an exterior part (not shown), by a screw fastening part 28 (Figure 3 (A)).

The cam barrel 14, on the other hand, engages with a focus ring (not shown) that serves as a focus key component that rotates around the optical axis via key grooves 26 and 27, and is rotated by the user. This rotation of the cam barrel 14 causes the bearing 19 that engages with the linear cam 18 to move along the diagonal cam 17 in the optical axis direction, and the focus lens 5 to move in the optical axis direction, thereby performing focus adjustment.

In the present embodiment, the guide tube 15 is produced by 3D printing the wear-resistant sliding parts of the linear cam 18, sliding parts 24 and 25, from different metal materials on a hollow cylindrical base material that serves as the base material of the lens barrel parts. The skeletal structure for maintaining the strength of the lens barrel parts or the entire completed lens barrel may also be produced by 3D printing, but the skeletal structure may also be produced by another method, such as die casting or cutting the base material. For example, a powder supply method is used for this 3D printing method.

Here, the guide tube 15, which corresponds to the lens barrel part of this embodiment, will be described in detail. The base material portion, which is the main part of the guide tube 15, is made from a hollow cylindrical base material 61 shown in FIG. 5. In this embodiment, after completion, a part of this base material 61 will include a main part of the optical characteristic portion that has optical characteristics such as light blocking properties over almost the entirety and anti-reflection properties on the inner surface. The base material 61 is formed by casting or hollow cutting of a rod-shaped metal material using a lathe. Alternatively, the hollow cylindrical base material 61 may be formed by a method such as welding both ends of a flat plate to form it into a cylindrical shape. The processing of this base material 61 corresponds to the process (first process) of forming the main shape portion of the optical characteristic portion having the specified optical characteristics of the guide tube 15.

Next, as shown in FIG. 6, the skeletal structure 62 (65 in FIG. 1) and the sliding parts 63 and 64 shown by diagonal lines in the figure are fabricated by 3D printing on the outer circumferential surface of the base material 61 (second process). For this 3D printing, a 3D printer using a powder supply method is used, and different metals are used as material powder for the skeletal structure 62 (65 in FIG. 1) and the sliding parts 63 and 64. In addition, the sliding parts 63 and 64 are 3D printed in a shape that takes excess material into consideration. For example, the sliding part 63 is 3D printed in an elongated hole shape that includes the edge of the linear cam 18, and then cut and removed as described below, leaving the cam edge. In addition, the sliding part 64 is 3D printed with a height that allows for a margin so that it will have the final dimensions (height) after subsequent cutting and removal.

Then, secondary processing is performed to remove the inner circumference of the base material 61 and the skeletal structure part 62 on the outer circumference side, and the through-hole of the linear cam 18 of the sliding parts 63 and 64, for example by cutting (third process), and the completed guide tube 15 is in the state shown in Figure 1.

As shown in FIG. 1, the skeletal structure 65 of the guide tube 15 has a lattice-based skeletal structure on the cylindrical outer circumferential surface to maintain the strength characteristics (e.g., rigidity) of the guide tube 15. This lattice-like structure can provide the guide tube 15 with rigidity against compression in the radial direction or in a direction parallel to the axis (usually coaxial with the optical axis of the focus lens 5) and against external forces in the torsional direction applied via the cam groove of the linear cam 18.

This lattice structure is composed of, for example, a number of regularly defined and arranged triangular or quadrilateral recesses 66. These recesses 66 constitute a lightweight section that reduces the overall weight by removing material. In other words, the regularly arranged recesses 66 remove material from almost the entire cylindrical structure of the skeletal structure 65, significantly reducing the weight of the skeletal structure 65.

Furthermore, the skeletal structure 65 includes a screw fastening hole 23 and seating surfaces 35 and 36 into which the bearing 22 is fastened with a screw, a seating surface and clearance for the screw fastening portion 28 with the lens barrel component outside the unit, an abutment surface 32 with the washer spring 21, and an abutment surface 33 that engages with the charge tube 20.

If the shape is as complex as that shown in FIG. 1, the skeletal structure 65, the sliding part of the linear cam 18, and the sliding parts 24 and 25 can be suitably produced from different metal materials using a powder feeding 3D printer 301. In general, parts produced by a 3D printer using the powder feeding method have lower accuracy than cutting, so it is desirable to create 3D print data 302 taking into account excess material, etc., so that the parts are made of a material with the desired characteristics after secondary processing by cutting.

In FIG. 7, when the skeletal structure 65 and the sliding part of the linear cam 18, and the sliding parts 24 and 25 are formed using the 3D printer 301, for example, the formation starts from the outer circumferential surface of the cylindrical base material 61. In this case, for example, the base material 61 is rotated around the axis of the base material 61 while switching materials and repeating the build-up formation.

During this 3D modeling, the 3D printer 301 is supplied with 3D print data 302 for modeling the skeletal structure 65, the linear cam 18, and the sliding parts 24 and 25. This 3D print data 302 is, for example, 3D CAD data of the skeletal structure 65 and the sliding parts 63 and 64 taking into account the above-mentioned excess material. In this case, the 3D printer 301 uses the 3D CAD data by decomposing it into layer (slice) data for performing build-up modeling for each material. Such layer (slice) data may be supplied to the 3D printer 301 as the 3D print data 302. When the 3D print data 302 is supplied to the 3D printer 301 from a server or a host device (not shown), the 3D print data 302 may be transmitted by network communication. Alternatively, the 3D print data 302 may be stored in a computer-readable recording medium such as various optical disks or flash memory devices and supplied to the 3D printer 301. In this case, these computer-readable recording media constitute the recording media of the present invention.

In the example of FIG. 7, the angle (α) between the direction parallel to the axis of the skeletal structure 62 (usually coaxial with the optical axis of the focus lens 5) and the inclined lattice is approximately 45°. This allows the guide tube 15 to maintain good strength characteristics (rigidity) against any external force in any of the above directions.

As described above, the skeletal structure 62 and the sliding parts 63 and 64 are 3D-formed by depositing different metals on the cylindrical base material 61 using a powder supply method, with a thickness that allows for sufficient excess material for subsequent cutting (third process). After that, secondary processing (third process) is performed to remove, for example, the inner circumference of the base material 61 and the skeletal structure 62 on the outer circumference side, or the through-hole of the long hole of the linear cam 18 of the sliding parts 63 and 64, for example, by cutting.

Figure 8 (A) shows a cross section of the base material 61 immediately after the skeletal structure 62 and the sliding parts 63 and 64 have been built up by 3D modeling. Also, Figure 8 (B) shows a cross section of the guide tube 15 in Figure 1 immediately after secondary processing has been performed by cutting.

In FIG. 8B, the inner light shielding parts 29 and 30 of the guide tube 15 are formed from a cylindrical base material 61, so that the optical characteristic part, which is the main part of the guide tube 15, can be provided with reliable light shielding properties. In addition, the inner light shielding part 29 can be subjected to anti-reflection surface treatment such as electrostatic flocking or matte coating. This inner light shielding part 29 can prevent unnecessary light from being reflected inside the lens barrel and causing ghosts and flares. In addition, in this example, the inner light shielding part 30 is composed of a light shielding wire formed by cutting or the like. However, if a light shielding wire structure is used for the inner light shielding part 30, the thickness of the guide tube 15 must be large, and in order to achieve a thin and lightweight structure, anti-reflection surface treatment by electrostatic flocking or matte coating may be more preferable.

The final shapes of the sliding parts 63, 24, 25, 64 and skeletal structure 65 of the linear cam 18 3D modeled on the guide tube 15 are formed by secondary machining using cutting. The through-holes of the sliding parts 63, 64 (Fig. 8(A)) are cut to form the linear cam 18 (Figs. 1 and 3). The metal material of the 3D modeled sliding parts 63, 64 remains as the structure of the edge of the long hole of the linear cam 18.

In the guide tube 15 of this embodiment 1, the inner surface light shielding parts 29, 30 and the skeletal structure part 65 are made of, for example, a magnesium alloy with a specific gravity of 1.8, as shown in FIG. 14, while the sliding part of the linear cam 18, the sliding parts 24, 25 are made of an aluminum alloy with a specific gravity of 2.68. In this case, as shown in the figure, the volume of the inner surface light shielding parts 29, 30 of this embodiment 1 is 4.95 cm^3 (^ indicates a power) and their weight is 8.91 g, while the volume of the skeletal structure part 65 is 10.23 cm^3 and their weight is 18.41 g. In addition, the volume of the sliding part of the linear cam 18, the sliding parts 24, 25 is 0.35 cm^3 and their final weight is 0.94 g, and in this example, the total weight of the guide tube 15 is 28.26 g.

On the other hand, Comparative Example (1) (1203) is an example of a typical guide tube shape without a lattice structure in which the recess 66 of this embodiment is padded, but made only from an aluminum alloy from the viewpoint of wear resistance. The total weight of this Comparative Example (1) (1203) is 58.56 g, and the structure of this embodiment 1 has achieved a weight reduction of approximately 52% in total weight.

In addition, since there is a possibility that light may be reflected by the outer periphery of the guide tube 15, causing ghosts and flares, the exposed parts of this skeletal structure 62 (65: Figure 1) may be painted, anodized, plated, or otherwise treated as necessary to impart anti-reflection properties.

In the above, the skeletal structure 65 is defined by a linear lattice structure, and has regularly arranged recesses as lightening portions. However, a shape determined by topology optimization analysis or the like may be used as the shape of the regularly arranged recesses as lightening portions to achieve the required weight reduction. Known examples of this type of topology optimization software include OptiStruct (product name) by Altair, and by using this type of topology optimization software, it is possible to distinguish between areas that require strength and areas that do not.

In the above, the structure of the guide tube 15 of the inner tube of the focus unit 4 has been exemplified as a lens barrel part, but the structure of the guide tube 15 may be implemented in a lens barrel part such as a fixed tube. The structure of the focus unit 4 exemplified above is also the same in a zoom unit for operating a zoom optical system, and the structure of the lens barrel part of this embodiment may be implemented in the lens barrel part that constitutes the zoom unit.

In this manner, a lens barrel component is obtained that includes a sliding portion that contacts another member, and a base portion that is integrated with the sliding portion and is made of a metal material with a lower specific gravity than the metal material of the sliding portion. The base portion has a skeletal structure that has predetermined strength characteristics and includes a number of regularly-arranged recesses, and the focus lens, which is an optical element, is firmly held by the base portion, which is a structure in which the skeletal structure is integrated with the base material.

The lens barrel parts of this embodiment can ensure the strength and abrasion resistance that meet the required specifications, and can also realize a small and lightweight lens barrel that has the necessary optical properties, such as light blocking and anti-reflection of unwanted light. Furthermore, the lens barrel of this embodiment can be used to realize, for example, a small and lightweight lens unit that has optical properties that meet the required specifications, and further, optical equipment such as a digital or silver halide camera that includes this lens unit. In this embodiment, an example is shown in which the skeletal structure is formed by 3D printing, but the skeletal structure may also be manufactured by other manufacturing methods (for example, die casting).

<Embodiment 2>
In this embodiment, as an example of the configuration of an optical component that employs the present invention, the structure of a cam barrel corresponding to cam barrel 14 equipped with an oblique cam whose basic structure is shown in Figures 3 and 4 is shown. Figure 9 shows the configuration of cam barrel 70 of this embodiment. Note that in Embodiments 2 to 4, the same reference numerals are used for members or parts that are the same as or equivalent to those in the above-mentioned Embodiment 1, and detailed explanations thereof will be omitted unless particularly necessary.

In the cam barrel 70, which corresponds to the lens barrel component of this embodiment, the sliding parts 63, 72, 73 of the diagonal cam 17, which require wear resistance, and the skeletal part are built up with different metals by 3D printing using a powder supply method on a base material formed into a cylindrical shape (first process) (second process). After that, for example, the inner circumferential surface of the base material 61, the skeletal structure part 65, and the long hole part of the diagonal cam 17 are removed by cutting or the like (third process). In particular, the lattice-shaped skeletal part that covers almost the entire cam barrel 70 is formed by penetrating and removing the cylindrical base material after the build-up process.

In the cam barrel 70 of this embodiment, first, a cylindrical base material 74 is formed as shown in FIG. 10, which constitutes the base material of the lens barrel component (first step). Next, as shown in FIG. 11, the skeletal structure 77, the sliding parts 75 and 76 shown with diagonal lines in the figure, and the sliding part 78 (FIG. 13(A)) are 3D modeled by 3D printing with build-up of different metals (second step). For this 3D modeling, a 3D printer using the same powder supply method as in embodiment 1 can be used. The method of supplying 3D print data for 3D modeling may be the same as in embodiment 1 above.

After that, secondary processing (third process) is performed to remove the long hole of the sliding part 75, remove the inside of the cylindrical base material 74, and remove part of the outer surface of the 3D modeled skeletal structure. This completes the cam cylinder 70 with the desired dimensions and shape as shown in Figure 9. Note that the base material 74 can be made of any material as long as the skeletal structure and sliding parts can be built up, but in this embodiment it is made of an aluminum alloy (first process).

As shown in FIG. 9, the skeletal structure 71 of the cam barrel 70 has a lattice-based skeletal structure on the cylindrical surface to maintain the rigidity and strength of the cam barrel 70. This lattice structure can provide the cam barrel 70 with rigidity against compression in the radial direction or in a direction parallel to the axis (usually coaxial with the optical axis of the focus lens 5) and against external forces in the torsional direction applied through the cam grooves of the diagonal cam 17.

The area defined by the lattice is made up of a number of triangular or quadrilateral-shaped through-holes 79 that are regularly defined and arranged by the lattice. These regularly arranged openings 79 remove material from almost the entire cylindrical structure of the skeletal structure 71, thereby making it possible to significantly reduce the weight of the skeletal structure 71.

Furthermore, the skeletal structure 71 has a key groove that engages with a focus ring as a focus key component and a fixing screw hole around the key groove. In particular, the sliding portion 73 engages with the bearing 22 (Fig. 4), and the sliding portion 72 on the inner surface (Fig. 13(B) below) engages with the sliding portions 24 and 25 of the guide tube 15 (Fig. 1).

For a shape with the level of complexity shown in FIG. 9, the skeletal structure 71 and the sliding parts 75, 72, and 73 of the diagonal cam 17 can be suitably produced from different first and second metal materials using a 3D printer 301 that uses a powder supply method, as shown in FIG. 12. When forming the skeletal structure 71 and the sliding parts 75, 76, and 78 using the 3D printer 301, for example, formation is started from the outer periphery of the cylindrical base material 74 in FIG. 12, and the material is switched while rotating the base material 74 around its axis, and build-up formation is repeated.

The skeletal structure 71 (77: Figs. 11 and 12) can be shaped in the same way as the skeletal structure 62 in Fig. 7. That is, even in the configuration of Fig. 12, the angle between the direction parallel to the axis of the skeletal structure 77 (usually coaxial with the optical axis of the focus lens 5) and the tilted lattice described above is set to a tilt angle (α) of approximately 45°. This makes it possible to maintain good rigidity against any external force in any of the above directions.

As described above, the skeletal structure 77 and the sliding parts 75, 76, and 78 are 3D-formed by depositing different metals on the cylindrical base material 74 using a powder supply method, with a thickness that takes into account the excess material required for the subsequent cutting (third process). After that, secondary processing (third process) is performed, for example by cutting to remove the inner periphery of the base material 74 and the through-hole of the sliding part 75 on the outer periphery.

Figure 13 (A) shows a cross section of the base material 74 immediately after the skeletal structure 77 and the sliding parts 75, 76, and 78 have been built up by 3D modeling. Also, Figure 13 (B) shows a cross section of the cam barrel 70 in Figure 9 immediately after secondary machining by cutting from the state in Figure 11.

The cam barrel 70 can be used by engaging the guide barrel 15 instead of the cam barrel 14 in FIG. 3(A). In that case, the guide barrel 15 engages with the inside of the cam barrel 70, and as described above, the guide barrel 15 has the inner light-shielding parts 29, 30 (FIG. 1). On the other hand, although the cam barrel 14 is an optical part that constitutes the completed lens barrel, it is sufficient that it has a mechanical function, and does not necessarily need optical properties such as light-shielding properties required for the guide barrel 15. Therefore, in the cam barrel 14, when the base material 74 is subjected to secondary processing and removed to form the skeletal structure part 71 (FIG. 13(B)), a through opening 79 may be formed instead of a recess. This allows for a significant weight reduction.

In the lens barrel part of this embodiment 2, the skeletal structure 71 can be made of a magnesium alloy with a specific gravity of 1.8, for example, as shown in FIG. 15, and the sliding part of the diagonal cam 17, the sliding parts 72 and 73 can be made of an aluminum alloy with a specific gravity of 2.68. In this case, the weight of the skeletal structure 71 of this embodiment 2 is 16.75 g, the final weight of the sliding part of the diagonal cam 17, the sliding parts 72 and 73 is 0.86 g, and the total weight of the cam barrel 70 in this example is 17.61 g. On the other hand, the comparative example (2) (1204) is an example in which a general cam barrel shape with hollowing is made only of an aluminum alloy from the viewpoint of wear resistance. The total weight of this comparative example (2) (1204) is 39.86 g, and the structure of this embodiment 2 achieves a weight reduction of about 56% in total weight.

In the above, the structure of the cam barrel 70 of the outer barrel of the focus unit 4 has been exemplified as a lens barrel part, but the structure of the guide barrel 15 may be implemented in a lens barrel part such as a fixed barrel. The structure of the focus unit 4 exemplified above is also the same in a zoom unit for operating a zoom optical system, and the structure of the lens barrel part of this embodiment may be implemented in the lens barrel part that constitutes the zoom unit.

As described above, according to this embodiment, it is possible to realize a small and lightweight lens barrel part that can ensure the strength and wear resistance that meet the required specifications of the lens barrel part. Furthermore, by using the lens barrel part of this embodiment, it is possible to realize, for example, a small and lightweight lens unit that combines optical characteristics that meet the required specifications, and further an optical device such as a digital or silver halide camera that includes this lens unit.

<Embodiment 3>
In this embodiment, a quick return mirror is shown as an example of an optical component to which the present invention is applied. In the following, a characteristic configuration of the main mirror holder of the quick return mirror will be particularly described.

Figure 16 shows the configuration of a single-lens reflex digital camera as an optical device equipped with a quick-return mirror of this embodiment. A camera body 2 is connected to a photographing lens 1. Light from a subject is photographed through optical lenses such as lens 3 included in the photographing lens 1. Before shooting, the light is reflected by the main mirror 7, passes through a prism 11, and then the photographed image is displayed to the photographer through a viewfinder lens 12.

In this embodiment, the main mirror 7 is also a half mirror, and the light that passes through the main mirror is reflected by the sub-mirror 8 in the direction of the AF (autofocus) unit 13, and this reflected light is used for distance measurement, for example. When shooting, the main mirror 7 and sub-mirror 8 are moved out of the optical path via a drive mechanism (not shown), the shutter 9 is opened, and the shooting light image incident from the shooting lens 1 is formed on the image sensor 10. In addition, the aperture 6 is configured so that the brightness and focal depth during shooting can be changed by changing the opening area.

It should be noted that the imaging element 10 of the single-lens reflex camera of FIG. 16 may be replaced with a silver halide film. In that case, the mirror holder of this embodiment may be configured in a similar manner to that described below. Also, the photographic lens 1 may be fixedly attached to the camera body 2, or the photographic lens 1 may be configured as an interchangeable lens that is detachable from the body of the camera body 2.

The primary mirror 7 is attached and supported by adhesive or the like to the primary mirror holder 80 shown in FIG. 17, and the swing position is controlled via the primary mirror holder 80. The swing position of the primary mirror 7 and primary mirror holder 80 in FIG. 16 is an observation position where the observation light is reflected in the direction of the viewfinder lens 12 different from that during shooting. When shooting, the primary mirror 7 and primary mirror holder 80 are swung by a drive mechanism (not shown) to the horizontal position in the figure, as shown by the arrow, in synchronization with the opening of the shutter 9. At this time, the sub-mirror 8 is folded in synchronization so that it is approximately flush with the primary mirror holder 80.

The purpose of swinging the primary mirror holder 80 is to move the primary mirror 7 out of the photographing optical path, and to block the optical path between it and the viewfinder lens 12 to prevent ghost images caused by light coming from the direction of the viewfinder lens 12. After shooting, that is, after the necessary exposure has been made to the image sensor 10, the shutter 9 is closed, and in sync with this, the mechanism quickly returns to the position shown in FIG. 16 to project the photographed image on the viewfinder. For this reason, the primary mirror 7 that is swingable via the primary mirror holder 80 and the surrounding mechanism are sometimes called quick return mirrors, etc.

The unit of the primary mirror holder 80, which includes the primary mirror 7 and the sub-mirror 8, is desired to be lightweight in order to improve drive characteristics such as oscillation speed and stopping time (quick return). However, with the conventional configuration, it was sometimes difficult to reduce the weight of the primary mirror holder 80, for example by making bold cuts in the thickness, from the standpoint of strength against shocks during drive, secure retention of the primary mirror 7, and blocking unnecessary light before, during, and after shooting.

In contrast, the primary mirror holder 80 of this embodiment 3 is configured, for example, as shown in FIG. 17. FIG. 17 is a perspective view of the primary mirror holder 80 of this embodiment 3 from the rear left side of the lower surface, and particularly illustrates the primary mirror holder 80 with the sub-mirror 8 removed. The skeletal structure 181 for maintaining strength and rigidity, and the optical characteristic part 86 having light-shielding or further anti-reflection properties, are made of a metal with a lower density than the sliding part. The base material part of the primary mirror holder 80 of this embodiment is integrated with the skeletal structure 181 or further the optical characteristic part 86, and the skeletal structure 181 may be rephrased as the base material part of the primary mirror holder 80. The skeletal structure 181 or the optical characteristic part 86 can be configured by die-casting the base material constituting the base material part of the primary mirror holder 80, or by cutting the base material constituting the base material part.

The base material constituting the substrate of the primary mirror holder 80 is a first metallic material with a low specific gravity (low density), such as a magnesium alloy. The sliding parts (81-85) of the primary mirror holder 80 are fabricated by build-up processing of a second metallic material that is more wear-resistant than the first metallic material.

For example, in this embodiment, the sliding parts (81-85) for the skeletal structure 181 and the optical characteristic part 86 are produced by 3D printing from a metal material that is more wear-resistant than the skeletal structure. For example, a powder supply method is used for this 3D printing method. That is, the quick return mirror of this embodiment, that is, the structure formed by combining the skeletal structure 181 of the primary mirror holder 80, the optical characteristic part 86, and the sliding parts (81-85), supports the primary mirror 7 and further the sub-mirror 8.

In FIG. 17, the primary mirror holder 80 has a rotation axis 81, and the above-mentioned swing drive is performed around this rotation axis 81. At the base of the rotation axis 81, 81, receiving surfaces 82, 82 are provided that abut and slide against a bearing (not shown) on the camera body 2 side and regulate the movement in the left-right direction in the figure.

As described above, the primary mirror holder 80 maintains its inclined position inserted into the primary optical path of the camera as shown in FIG. 16, except when the shutter is driven. At this time, the receiving surfaces 83, 83 of the primary mirror holder 80 abut against a positioning member (not shown) of the camera body 2 at the rear end.

Like the main mirror 7, the sub-mirror 8 also needs to be moved out of the main optical path so that it assumes a horizontal position in FIG. 16. For this reason, the main mirror holder 80 is provided with rotation shafts 84, 84 for swinging the sub-mirror 8 so that it assumes a position parallel to the main mirror, and at its base are receiving surfaces 85, 85 that come into contact with and slide against a holder (not shown) that holds the sub-mirror 8. The central portion of the skeletal structure 181 is an opening that passes light that travels toward the sub-mirror 8 via the main mirror 7, which is made of a half mirror.

It is also necessary to prevent ghosts and flares caused by light reflecting off the back surface when the primary mirror holder 80 is moved out of the optical path. For this reason, an optical characteristic section 86 with anti-reflection properties consisting of light-shielding lines is formed in the necessary areas on the back surface of the primary mirror holder 80. The anti-reflection properties formed by the optical characteristic section 86 may also be formed by post-processing such as matting or painting. Note that a similar anti-reflection surface can also be formed by painting, for example, on the receiving surfaces 83, 83 that are oriented in the direction of the primary optical axis when moved to the horizontal position in Figure 16 during shooting.

The rotation shafts and receiving surfaces indicated by 81 to 85 above correspond to the sliding parts of the primary mirror holder 80, which is an optical component of this embodiment. Below, these parts may be collectively referred to as "sliding parts (81 to 85)."

In the manufacture of the primary mirror holder 80 of this embodiment, first, the shape shown in FIG. 18 constituting the skeletal structure 181 and the optical characteristic portion 86 is formed, for example, by die casting (first step). Next, as shown in FIG. 19, the sliding portions (81-85) indicated by the diagonal lines in the figure are 3D modeled by 3D printing with a metal different from that of the skeletal structure 181 and the optical characteristic portion 86 (second step). For this 3D modeling, a 3D printer using the same powder supply method as in embodiment 1 can be used. The method of supplying 3D print data for 3D modeling may be the same as in embodiment 1 above.

Then, secondary processing (third step) is performed to remove excess material added during 3D printing. This completes the primary mirror holder 80 with the desired dimensions and shape as shown in Figure 17. Note that light may be reflected by this skeletal structure 181 and the sliding parts (81-85), causing ghosts and flares. In this case, anti-reflective properties may be imparted by painting or coloring with anodizing.

In the primary mirror holder 80 of this embodiment 3, the skeletal structure 181 and the optical characteristic section 86 can be made of a magnesium alloy with a specific gravity of 1.81, and the sliding sections (81 to 85) can be made of an aluminum alloy with a specific gravity of 2.68, as shown in FIG. 20. In this case, the combined weight of the skeletal structure 181 and the optical characteristic section 86 of this embodiment 3 is 1.65 g, the combined weight of the sliding sections (81 to 85) is 0.05 g, and the total weight of the primary mirror holder 80 in this example is 1.65 g. On the other hand, the comparative example (3) (1205) is an example in which the shape of a general primary mirror holder is made only of an aluminum alloy from the viewpoint of wear resistance. The total weight of this comparative example (3) (1205) is 2.36 g, and the structure of this embodiment 3 achieves a weight reduction of about 30% in total weight.

Figure 21 shows the results of comparing the primary mirror holders of this embodiment 3 and Comparative Example (3). Figure 21 shows the change in the rotation angle of the primary mirror holder for each primary mirror holder when a torque spring (details not shown) with a torque spring constant of approximately 0.01 N·mm/deg is swung 90° around the rotation axis 81 and released from a charged state. As is clear from Figure 21, the primary mirror holder of this embodiment 3 requires 7 ms less time to rotate 45° from the horizontal position to the observation position compared to the primary mirror holder of Comparative Example (3), and it can be seen that the swing speed is faster due to the lighter weight.

As described above, according to this embodiment, it is possible to realize a small and lightweight quick-return mirror that can ensure strength and abrasion resistance that meet the required specifications, and also has the necessary optical properties, such as light blocking properties and anti-reflection properties for unwanted light. Furthermore, the quick-return mirror of this embodiment can be used to realize optical devices such as high-performance digital or silver halide cameras.

1...taking lens, 2...camera body, 3...lens, 4...focus unit, 5...focus lens, 6...aperture, 7...main mirror, 8...sub-mirror, 9...shutter, 10...image sensor, 11...prism, 12...finder lens, 13...AF unit, 14...cam barrel, 15...guide barrel, 16...focus lens holder, 17...diagonal cam, 18...linear cam, 19...bearing, 20...charge barrel, 21...washer spring, 22...bearing, 24, 25, 72, 73...sliding part, 29, 30...inner light shielding part, 32...contact surface, 35, 36...screw seating surface, 61...base material, 62, 65, 77...skeletal structure part, 63, 64, 75, 76, 78...sliding part, 301...3D printer, 302...3D print data, 80...primary mirror holder, 181...skeletal structure part, 81-85...sliding part, 86...optical characteristic part.

Claims (20)

A step of performing build-up molding on a base part having a portion made of a first metal material using a second metal material having a main component different from the first metal material;
forming a through hole in the base portion so as to remove a third portion of the second portion, a fourth portion of the second metal material covering the third portion, and the third portion of the base portion, while leaving a first portion of the base portion made of the first metallic material, a first portion of the second portion of the base portion covered with the second metallic material, and a second portion of the second metallic material covering the first portion,
A method for manufacturing an optical component, wherein the first portion and the third portion are not covered with the second metal material in a direction in which the third portion and the fourth portion are aligned, the first portion is continuous with the first portion, and the second portion is continuous with the fourth portion. 2. The method of claim 1, wherein the removing step is performed by cutting. 3. A method for manufacturing an optical component as described in claim 1 or 2, wherein multiple portions of the second portion face each other through the through hole, and the multiple portions of the second portion are located between the multiple portions of the first portion. 4. The method of manufacturing an optical component according to claim 1, wherein the first metallic material has a lower specific gravity than the second metallic material. 5. The method of manufacturing an optical component according to claim 1, wherein the first metallic material is a magnesium alloy. 6. The method of manufacturing an optical component according to claim 1, wherein the second metallic material is an aluminum alloy. 7. The method for producing an optical component according to claim 1, wherein the substrate portion is cylindrical. 8. The method for producing an optical component according to claim 1, wherein the substrate portion includes a skeletal structure portion that imparts predetermined strength characteristics to the optical component. 9. The method for producing an optical component according to claim 8, wherein the skeletal structure is formed by cutting or deposit molding a base material constituting the substrate. 10. The method for manufacturing an optical component according to claim 1, wherein the build-up molding is performed by a 3D printer. a substrate portion made of a first metallic material;
a portion made of a second metallic material supported and fixed to the base portion;
a bearing that slides on the portion;
The optical device, wherein the first metallic material has a lower specific gravity than the second metallic material. The portion made of the second metallic material is a first portion,
a second portion made of a third metallic material;
the bearing slides on the second portion such that the first portion moves relative to the second portion;
The optical instrument of claim 11 , wherein the first metallic material has a lower specific gravity than the third metallic material. A first substrate portion made of a first metallic material;
a first portion made of a second metallic material and supported and fixed to the first base portion;
a second portion made of a third metallic material that slides against the first portion;
a second base portion made of a fourth metal material that supports and fixes the second portion;
The first substrate portion moves relative to the second substrate portion;
An optical device, wherein the first metal material has a lower specific gravity than the second metal material and the third metal material, and the fourth metal material has a lower specific gravity than the third metal material. The substrate portion made of the first metal material is a first substrate portion,
a second base portion made of a fourth metal material that supports and fixes the second portion;
The first substrate portion moves relative to the second substrate portion;
The optical instrument of claim 12 , wherein the fourth metallic material has a lower specific gravity than the third metallic material. The optical device according to claim 11 , comprising an optical element supported by the base portion. The optical device according to claim 11 , wherein the base portion made of the first metallic material is included in a lens barrel component. 17. The optical instrument according to any one of claims 11 to 16, wherein the first metallic material is a magnesium alloy. 18. The optical instrument according to any one of claims 11 to 17, wherein the second metallic material is an aluminium alloy. 15. The optical instrument of claim 14, wherein the fourth metallic material is a magnesium alloy. 20. The optical instrument according to claim 12, wherein the third metallic material is an aluminium alloy.

Images