JP2006074654A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that miniaturization of a lens barrel is difficult in a conventional imaging apparatus since the imaging apparatus must be disassembled once for repair when some fault occurs in an ND filter and therefore a gap must be created in design between a third lens group as a fixed lens and a movable blade. <P>SOLUTION: A filter assembly 6 having the ND filter is arranged between the last lens surface in the lens barrel 1 and an imaging device 9. The ND filter in the filter assembly 6 has a plurality of first filter areas with different transmission and a second optically transparent filter area. The filter assembly 6 arranges any of filter areas with respective transmission of the plurality of first filter areas and the second filter area of the ND filter in an optical path of incidednt light which reaches a light receiving surface of the imaging device 9 from the lens barrel 1 by a transfer mechanism including a lever 11, etc. Its arrangement position is exactly positioned based on output signals of photoreflectors 12 and 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus such as a video camera or a digital still camera provided with a mechanism for adjusting the amount of light using an ND (neutral density) filter having different densities.

  In a conventional imaging device, when photographing a bright place such as outdoors, an iris mechanism called an iris works to reduce the amount of light and suppress the brightness. In addition, when it is desired to focus only on a certain object, an ND filter can be used to blur the periphery. In view of this, there has been known an imaging apparatus that uses an ND filter to prevent small aperture blur due to excessive iris diaphragm diameter, and also suppresses the amount of light (see, for example, Patent Document 1).

  In this conventional imaging apparatus, an ND filter is attached to a movable blade that is slidably supported in the casing, and the ND filter is formed larger than a light passage hole formed in the casing, and the movable blade is driven by a driving mechanism. The structure is such that the movable blade passing through or the ND filter and the light passage hole face each other with the movable blade stopped, and the presence or absence of the ND filter or the concentration of the ND filter is changed stepwise. It has a mechanism to change In this conventional imaging apparatus, the ND filter is attached to the movable blade, passes through the transparent part or the ND filter and the light passage hole, and further passes through the third lens group to function as a focusing lens. The amount of incident light entering the four lens groups is adjusted.

JP-A-8-248472

  However, in the above-described conventional imaging device, if something goes wrong with the ND filter, it must be disassembled once for repair, and the ND filter is movable with the third lens group, which is a fixed lens. Since it is necessary to create a gap in design because it is placed between the blades, it is difficult to reduce the size of the imaging apparatus.

  The present invention has been made in view of the above points, and an object thereof is to provide an imaging device that can be downsized, is excellent in assembly / disassembly and productivity of an ND filter, and can be used as a general-purpose product. To do.

  In order to achieve the above object, the present invention provides an imaging apparatus having a mechanism for taking in and out an ND filter having a plurality of filter regions having different transmittances in an optical path from an imaging lens system to a light receiving surface of an imaging element. The ND filter has a plurality of ND filter areas having different transmittances and areas not functioning as an ND filter, each of which is composed of the area of the effective pixel area of the imaging element in the emitted light emitted from the imaging lens system. , A moving mechanism for moving the ND filter so that the emitted light is transmitted through a filter region having a desired transmittance in the ND filter region or a region not functioning as an ND filter, and a plurality of movement mechanisms by moving the ND filter by the moving mechanism. Which of the ND filter area of each transmittance and the area that does not function as the ND filter area are located in the optical path Characterized by comprising a detecting unit that.

  According to the present invention, the filter region and the ND filter having any one of the plurality of filter regions having different transmittances of the ND filter by the moving mechanism that moves the ND filter provided between the imaging lens system and the imaging element. Any of the regions that do not function as the ND filter region can be disposed in the optical path, and the ND filter region or the region that does not function as the ND filter can be detected by the detection means in the optical path.

  In order to achieve the above object, the image pickup apparatus according to the present invention includes a moving mechanism, a detecting unit, and an ND filter that constitute a filter unit that can be removed separately from the image pickup lens system and the image pickup element. An optical low-pass filter that transmits outgoing light emitted from the imaging lens system is fixed at a position in the filter unit that is close to and away from the imaging lens system.

  In the present invention, the moving mechanism, the detection means, and the ND filter can be removed separately from the imaging lens system and the imaging element, and the optical low-pass filter is disposed close to and away from the ND filter. Adherence of dust can be prevented with an optical low-pass filter.

  According to the present invention, any one of a plurality of filter regions having different transmittances of the ND filter and a region that does not function as the ND filter can be accurately positioned and arranged in the optical path by the detection unit. Even when the incident light of the image sensor is not attenuated, it passes through a region that does not function as an optically transparent ND filter in the ND filter, so that the same optical path length as that when the incident light is attenuated can be obtained. When the incident light is not attenuated, the same focus setting as that when the incident light is attenuated can be obtained.

  Further, according to the present invention, since the filter unit including the moving mechanism, the detection unit, and the ND filter can be removed separately from the imaging lens system and the imaging element, conventionally, the ND filter is a fixed lens in the imaging lens system. In order to put it between a certain third lens group and the movable blade, a gap must be created in the design, but the gap becomes unnecessary, and this makes it possible to reduce the size of the imaging lens system and hence the imaging device. .

  Further, according to the present invention, when there is a problem with the ND filter, it is possible to easily replace the ND filter by removing the filter unit including the ND filter without disassembling the lens barrel. It can also be used as a product.

  Furthermore, according to the present invention, since the optical low-pass filter is disposed close to and away from the ND filter, dust can be prevented from adhering to the ND filter.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing the overall configuration of an embodiment of an imaging apparatus according to the present invention. In the figure, a lens barrel 1 is a barrel in which a plurality of lens groups are all housed. The optical LPF (low-pass filter) press 2, optical LPF 3, main frame 4, stud 5, filter assembly (Assy) 6, cover 7, sheet 8, CCD (in order) from the final surface of the final lens group in the lens barrel 1 An image pickup device 9 and a base 10 constituted by a charge coupled device) are disposed.

  Further, one end of a lever 11 is rotatably fitted to the lower portion of the filter Assy 6, and is configured to be movable in stages in the vertical direction in the drawing by the rotation of the lever 11. The main frame 4 and the cover 7 are provided with openings 4 a and 7 a in the center, respectively, and the filter Assy 6 is sandwiched between the main frame 4 and the cover 6. In addition, the photo reflectors 12 and 13 are arranged and fixed in the openings 7 b and 7 c of the cover 7.

  Thereby, the photo reflector 12 is disposed at a first predetermined position obliquely below the central opening 7 a of the cover 7, and the photo reflector 13 is disposed second obliquely above the central opening 7 a of the cover 7. It is arranged at a predetermined position. The photo reflectors 12 and 13 output a low level signal when the opposing reflecting surfaces are black or when the opposing reflecting surfaces are separated by a predetermined distance or more, and high level signals when the opposing reflecting surfaces are white. Is output.

  Therefore, the reflecting surface facing the photo reflectors 12 and 13 becomes the filter holder 14 of the main frame 4 or the filter Assy 6 described later, so the surface of the photo reflector 12 and 13 side of the main frame 4 is made black by painting or the like. By separately painting the surface of the 14 photo reflectors 12 and 13 side into black and white by painting or the like, the filter 15 to be described later becomes a combination of the output signal levels of the photo reflectors 12 and 13 as shown in FIGS. It is possible to detect in which position.

  As shown in FIGS. 1 and 2, the main frame 4 has an opening 4a at the center, and an optical LPF 3 having a slightly larger diameter than the opening 4a is shown in the perspective view of FIG. The main frame 4 is attached so as to close the opening 4a.

  Thereby, in this embodiment, the incident light emitted from the lens barrel 1 is an opening 2a drilled in the center of the optical LPF retainer 2 and the optical LPF 3 attached to the opening 4a of the main frame 4. The filter Assy 6 enters the image sensor 9 through a filter 15 described later, an opening 7 a of the cover 7, and an opening 8 a formed in the center of the sheet 8. Here, the openings 7 a and 8 a are about the size of the effective pixel area of the image sensor 9. The optical LPF 3 for removing the infrared rays contained in the incident light is disposed close to and away from the filter 15, so that dust can be prevented from adhering to the filter 15.

  For example, as shown in the exploded perspective view of FIG. 4, the filter Assy 6 has a structure in which a filter 15 having a thin plate shape and a rectangular front shape is narrowed in front and back by a filter holder 14 and a filter frame 16, respectively. A rectangular opening 14 a having a slightly smaller diameter than the filter 15 is formed in the center of the filter retainer 14. Further, the flat filter frame 16 accommodates the filter 15 in a peripheral wall 161 having a small front-rear width formed to protrude forward along the peripheral edge thereof, and is integrally formed with the peripheral wall 161 at a lower portion of the peripheral wall 161. A slot-like opening 16a is formed in the formed tongue piece 162. In addition, two protrusions 163 are formed on the right and left side portions of the filter frame main body so as to protrude outward two by two.

  The filter 15 is formed as an ND filter, for example, on a transparent substrate by vacuum deposition, and is equally divided into three filter regions 151, 152, and 153 as shown in FIG. The first filter region 151 is set to the ND filter characteristic of the first density (transmittance), the second filter region 152 is set to the ND filter characteristic of the second density (transmittance), and the third The filter region 153 is set to an optically transparent filter characteristic that allows all wavelengths to pass through without being absorbed.

  Here, the ND filter characteristic is a neutral density (achromatic) filter characteristic that absorbs all wavelengths equally, but the ND filter characteristic of the first density is the ND filter characteristic of the second density. For example, since the density is set to be darker (transmittance is small), the amount of incident light when passing through the first filter region 151 is larger than when passing through the second filter region 152. Will be attenuated.

  Further, the opening 16a of the filter frame 16 of the filter Assy6 is formed on a protruding portion 11c formed to protrude forward at the tip of the arm portion 11b of the lever 11, as shown in FIG. 6 and FIGS. It is loosely fitted. In the lever 11, the stud 5 is fitted in a hole 11d drilled in the center portion, and the protruding portion 11c is configured to be rotatable about the rotation shaft. Further, the lever 11 has a protrusion 11a formed at the front end of the arm portion on the side facing the arm portion 11b with the hole 11d as the center, and the protrusion 11a is driven in the vertical direction by a drive mechanism (not shown). The

  One end of the stud 5 is fixed to a predetermined position of the main frame 4, and the other end is fixed to a predetermined position of the cover 7. Further, the protrusion 163 of the filter frame 16 is slidably fitted into two parallel grooves 41 formed in the main frame 4 and extending in the vertical direction. As a result, the filter Assy 6 is configured to be movable up and down between the main frame 4 and the cover 7 while being guided by the groove 41 as the lever 11 rotates as described above.

  Here, when the lever 11 is stationary in the state of FIG. 6, the filter Assy 6 is stationary at the uppermost position of the movable range, and at this time, the optical LPF 3 attached to the main frame 4 and the opening of the cover 7 (not shown). The part 7 a is set so as to be spaced apart from the first filter region 151 of the ND filter characteristic of the first density of the filter 15. Accordingly, at this time, the incident light that has passed through the optical LPF 3 passes through the first filter region 151 of the filter 15, and further passes through the opening 7 a of the cover 7 and enters the image sensor 9. As a result, the amount of light incident on the image sensor 9 is greatly attenuated by the first filter region 151.

  Further, as shown in FIG. 6, when the filter Assy 6 is stationary at the uppermost position of the movable range, it faces the photo reflector 12 at the lower position among the photo reflectors 12 and 13 shown in FIG. Since the reflection surface is the surface of the main frame 4 coated in black, the output signal of the photo reflector 12 becomes low level, while the reflection surface facing the photo reflector 13 in the upper position is coated on the white of the filter holder 14. Therefore, the output signal of the photoreflector 13 becomes high level. Thereby, it can be detected from the output signal levels of the photo reflectors 12 and 13 that the filter Assy 6 is stationary at the uppermost position of the movable range.

  Further, when the lever 11 is stationary in the state of FIG. 7, the filter Assy 6 is stationary at an intermediate position of the movable range, and at this time, the optical LPF 3 attached to the main frame 4 and the opening 7a of the cover 7 (not shown). Are set so as to be opposed to the second filter region 152 of the second density ND filter characteristic of the filter 15. Accordingly, at this time, the incident light that has passed through the optical LPF 3 passes through the second filter region 152 of the filter 15, further passes through the opening 7 a of the cover 7, and enters the image sensor 9. As a result, the light incident on the image sensor 9 is attenuated by the second filter region 152 by a small amount of light.

  Also, as shown in FIG. 7, when the filter Assy 6 is stationary at the middle position of the movable range, the reflecting surfaces facing the photo reflectors 12 and 13 shown in FIG. Since the coated surface is formed, both the output signals of the photo reflectors 12 and 13 are at a high level. Thereby, it can be detected from the output signal levels of the photo reflectors 12 and 13 that the filter Assy 6 is stationary at an intermediate position in the movable range.

  Further, when the lever 11 is stationary in the state of FIG. 8, the filter Assy 6 is stationary at the lowest position of the movable range, and at this time, the optical LPF 3 attached to the main frame 4 and the opening of the cover 7 (not shown). 7a is set so as to be opposed to the third filter region 153 of the filter 15 having optically transparent characteristics. Accordingly, at this time, the incident light that has passed through the optical LPF 3 passes through the third filter region 153 of the filter 15 and further passes through the opening 7 a of the cover 7 and enters the image sensor 9. Thereby, the amount of light incident on the image sensor 9 is not attenuated by the transparent third filter region 153.

  As shown in FIG. 8, when the filter Assy 6 is stationary at the lowest position in the movable range, the reflection facing the photo reflector 13 at the upper position of the photo reflectors 12 and 13 shown in FIG. Since the surface is the surface of the main frame 4 coated in black, the output signal of the photo reflector 13 is at a low level, while the reflective surface facing the photo reflector 12 in the lower position is coated on the white of the filter holder 14. Therefore, the output signal of the photoreflector 12 becomes high level. Thereby, it can be detected from the output signal levels of the photo reflectors 12 and 13 that the filter Assy 6 is stationary at the lowest position in the movable range.

  When the filter Assy 6 is located at a position (exception position) that is not one of the above-described FIGS. 6, 7 and 8, the reflecting surface facing the photo reflectors 12 and 13 is applied to the black color of the filter holder 14. Therefore, the output signals of the photo reflectors 12 and 13 are both at a low level, so that an exceptional position can be detected.

  Here, in the present embodiment, when the light incident on the image pickup device 9 is not attenuated, the light is not passed through, but as shown in FIG. The filter region 153 is allowed to pass. For this reason, in the case of passing through, the optical path length changes between when the light amount is attenuated and when the light passes through the filter, and the focus of the incident light of the image sensor 9 is different. Since the optical path length does not change because the light is passed through the third filter region 153 of the filter 15 having the same thickness as that when the light is attenuated, it is unnecessary to correct the focus of the incident light of the image sensor 9. There is.

  As described above, in the present embodiment, the lever 11 is rotated and the filter Assy 6 is stopped at the position shown in FIG. 6, FIG. 7, or FIG. It can be varied accordingly. Further, based on the output signals of the photo reflectors 12 and 13, the filter Assy6 can be accurately stopped at the position of FIG. 6, FIG. 7 or FIG.

  Further, in the present embodiment, as shown in FIG. 1, a filter unit including a main frame 4 to which an optical LPF 3 is attached, a filter Assy 6 to which a lever 11 is attached, and a cover 7 is connected to the lens barrel 1. Since it is arranged between the image pickup device 9 and the lens barrel 1 is not disassembled, only the filter unit can be easily removed from between the lens barrel 1 and the image pickup device 9.

  Thereby, in this embodiment, when any trouble occurs in the filter 15, without removing the lens barrel 1, only the filter unit is removed from between the lens barrel 1 and the image sensor 9, The lens unit can be replaced with a new filter unit, or the removed filter unit can be disassembled and the filter in the filter unit can be replaced with a new filter 15, and then the filter unit can be reassembled and returned to its original position. Compared to a conventional imaging device that requires the lens barrel 1 to be disassembled to replace the filter, the filter can be replaced very easily. Therefore, in this embodiment, there is an effect that the filter 15 can be used as a general-purpose product.

  Further, in the present embodiment, it is possible to eliminate the gap between the third lens group, which is a fixed lens in the lens barrel, and the movable blade, which is necessary in the conventional imaging apparatus. As a result, the lens barrel 1 Can be miniaturized.

  The present invention is not limited to the above embodiment. For example, the filter 15 has a structure having three filter regions having different filter characteristics, but may be two or more different filter regions. That's fine.

1 is an exploded perspective view showing an overall configuration of an embodiment of an imaging apparatus of the present invention. FIG. 2 is an exploded perspective view of an optical LPF and a main frame in FIG. 1. FIG. 2 is a perspective view of a main frame to which the optical LPF in FIG. 1 is attached. It is a perspective view which shows the relative positional relationship of the filter holder in FIG. 1, a filter, and a filter frame. It is explanatory drawing of the filter area | region of one Embodiment of the filter in FIG. It is a front view of the mechanism of the principal part when the filter in FIG. 1 exists in a 1st position. It is a front view of the mechanism of the principal part when the filter in FIG. 1 exists in a 2nd position. It is a front view of the mechanism of the principal part when the filter in FIG. 1 exists in a 3rd position.

Explanation of symbols

1 Lens barrel 3 Optical LPF
4 Main frame 5 Stud 6 Filter assembly (Assy)
7 Cover 9 Image sensor 11 Lever 12, 13 Photo reflector 14 Filter holder 15 Filter 16 Filter frame 151 Filter area of ND filter characteristic of first density 152 Filter area of ND filter characteristic of second density 153 Optically transparent Filter area for characteristics

Claims (2)

An image pickup apparatus having a mechanism for taking in and out an ND filter having a plurality of filter regions having different transmittances in an optical path from an image pickup lens system to a light receiving surface of an image pickup element,
The ND filter includes a plurality of ND filter regions having different transmittances and regions that do not function as ND filters, and each region has an area of an effective pixel region of the imaging element in the emitted light emitted from the imaging lens system. Have
A moving mechanism for moving the ND filter so that the emitted light passes through a filter region having a desired transmittance in the ND filter region or a region not functioning as the ND filter;
Detection means for detecting which of the plurality of ND filter regions has a transmittance region and a region that does not function as the ND filter region are located in the optical path by the movement of the ND filter by the moving mechanism; An imaging device comprising the imaging device. The moving mechanism, the detection unit, and the ND filter constitute a filter unit that is removable from the imaging lens system and the imaging element, and a position in the filter unit that is close to and spaced from the ND filter. The imaging apparatus according to claim 1, wherein an optical low-pass filter through which outgoing light emitted from the imaging lens system passes is fixed.

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