JP2006267863A - Lens barrel and lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact lens barrel equipped with an ND (Neutral Density) filter, and to provide a lens unit. <P>SOLUTION: In the lens unit 10, the open aperture diameter D1 of a shutter unit 55 and the maximum image forming diameter D2 at the image forming position P1 of a photographic lens satisfy a condition 0.6<D2/D1<1.1. A filter unit 56 is arranged near a luminous flux diameter minimum position P3 where the luminous flux diameter D1 of photographing light 79 becomes the minimum between a diaphragm position P2 and the image forming position P1. Since the ND filter 77 is inserted at a position where the luminous flux diameter D1 is small in the optical path of the photographing light 79, the outside diameter of the ND filter 77 is made small and also the retreat space of the ND filter 77 is made small. Therefore, the filter unit 56 is miniaturized to make the outside diameter of the lens unit 10 small. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel and a lens unit that limit the amount of photographing light by a diaphragm and an ND filter.

  In recent years, electronic cameras such as digital cameras have become popular. Such an electronic camera includes an image sensor (for example, a CCD) that captures a subject image by photoelectric conversion, and a diaphragm that adjusts the amount of light incident on the image sensor.

  However, in such an electronic camera, when the aperture diameter of the stop is smaller than a certain value, there is a problem that the image quality of the image picked up by the image pickup device deteriorates due to the light diffraction phenomenon. In order to solve such a problem, a lens barrel including an ND (Neutral Density) filter that is detachably inserted into an optical path of photographing light is known. In this lens barrel, an ND filter can be inserted into the optical path to limit the amount of light incident on the image sensor. For this reason, it is possible to limit the amount of light without making the aperture diameter of the stop small, and it is possible to prevent the deterioration of image quality as described above.

Further, when such ND filters, shutters, and diaphragms are collectively arranged at one place, it is necessary to arrange them so that their operation spaces do not overlap, and there is a problem that the lens barrel becomes large. In order to solve such a problem, a lens barrel in which an ND filter is disposed at a position away from a shutter and a diaphragm is known (for example, see Patent Document 1).
JP 2004-151503 A

  However, since the lens barrel described in Patent Document 1 needs to move the ND filter between the insertion position where the lens barrel is inserted into the optical path and the retract position where the lens barrel is retracted from the optical path, a retreat space for the ND filter is ensured. Therefore, there is a problem that the outer diameter of the lens barrel increases.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a small lens barrel and a lens unit including an ND filter.

  In order to solve the above problems, a lens barrel of the present invention is a photographic lens, a diaphragm that adjusts the amount of photographic light by changing an aperture diameter, and a removably inserted optical path of the photographic light, And an ND filter for dimming the photographing light, and the aperture stop diameter D1 of the stop and the maximum image forming diameter D2 at the image forming position of the photographing lens are such that 0.6 <D2 / D1 <1.1 And the ND filter is inserted in the vicinity of the minimum beam diameter position where the beam diameter of the photographing light becomes the smallest between the stop and the imaging position. It is.

  A filter unit that holds the ND filter and moves the ND filter between an insertion position inserted into the optical path and a retracted position retracted from the optical path is provided in the vicinity of the minimum beam diameter position. Preferably it is.

  A lens unit according to the present invention includes the lens barrel described above and an image sensor that is disposed in the lens barrel and captures a subject image formed by the photographing lens, and is detachably attached to the camera body. It is characterized by that.

  According to the lens barrel of the present invention, the ND filter that is removably inserted into the optical path of the photographing light is inserted in the vicinity of the position where the luminous flux of the photographing light is minimized between the stop and the imaging position. Therefore, the outer diameter of the ND filter can be reduced. Further, the retreat space for retracting the ND filter from the optical path of the photographing light can be reduced. For this reason, it is possible to reduce the outer diameter of the lens barrel and reduce the size.

  The filter unit is disposed in the vicinity of the position where the luminous flux of the photographing light becomes the smallest, and holds the above-described ND filter and includes a position where it is inserted into the optical path of the photographing light and a retreat position where it is retracted from the optical path. The ND filter is moved between them. For this reason, the outer diameter of the ND filter can be reduced to reduce the size of the filter unit, and the outer diameter of the lens barrel can be reduced.

  A lens unit 10 shown in FIG. 1 is an interchangeable lens barrel that is detachably attached to a camera body 11, and stores a CCD that is an image sensor as will be described later. An objective lens 20 and an autofocus sensor (hereinafter referred to as AF sensor) 21 are exposed on the front surface of the lens unit 10, and a mount portion 22 is provided on the rear surface.

  The lens unit 10 includes a focus ring 23, a zoom ring 24, and an aperture ring 25. Moreover, the lock release button 26 is provided in the outer peripheral surface of these rings 23-25, respectively, When these lock release buttons 26 are pressed, these can be rotated.

  On the front surface of the camera body 11, a mount unit 30, a release button 31, and a strobe light emitting unit 32 that emits strobe light toward the subject are provided. An operation unit 36 including a power button 33, a shutter button 34, and an operation dial 35 is provided on the upper surface. The power button 33 is pressed when the camera body 11 is turned on or off. The shutter button 34 is pressed when shooting. The operation dial 35 is operated when switching between the shooting mode and the reproduction mode. An LCD (not shown) is provided with an LCD for displaying images, setting screens, and the like.

  When the lens unit 10 is attached to the camera body 11, the lens unit 10 is attached to the camera body 11 by inserting the mount portion 22 into the recess 30 a formed in the mount portion 30. Thus, when the lens unit 10 is attached to the camera body 11, the lens unit 10 and the camera body 11 are electrically connected. The release button 31 is pressed when the lens unit 10 is removed from the camera body 11.

  In this lens unit 10, the zoom ring 24 is adjacent to the aperture ring 25, and between the shortened position where the entire length of the unit is shortened and the extended position where the entire length of the unit is elongated by moving the zoom ring 24 forward. The entire length of the unit can be expanded and contracted. When the lens unit 10 is not used, the zoom ring 24 is moved to the shortened position, and when the lens unit 10 is used, the zoom ring 24 is moved to the extended position. The zoom ring 24 can be rotated when moved to the extended position.

  Below, the structure of this lens unit 10 is demonstrated using FIGS. The lens unit 10 includes a fixed cylinder 40, a moving cylinder 41, a cam cylinder 42, and a cover cylinder 43.

  The above-described mount portion 22 is provided on the back surface of the fixed cylinder 40, and the fixed cylinder 40 is fixed to the camera body 11. In addition, three guide shafts 40 a are provided at the front end portion of the fixed cylinder 40. The tip of the guide shaft 40a protrudes from the outer peripheral surface and the inner peripheral surface, and the three guide shafts 40a are arranged at three positions in the circumferential direction with the optical axis L as the center. A diaphragm ring 25 is rotatably provided on the outer peripheral surface on the rear end side.

  The moving cylinder 41 is disposed inside the fixed cylinder 40. The movable cylinder 41 is provided with three guide grooves 41a that are formed substantially parallel to the optical axis L and engage with the guide shaft 40a. For this reason, the movable cylinder 41 moves straight (between the position stored in the fixed cylinder 40 (position shown in FIG. 2) and the position pulled forward from the fixed cylinder 40 (position shown in FIG. 3) ( It is movable in the direction of the optical axis L), and rotation in the circumferential direction around the optical axis L is restricted.

  The cam cylinder 42 is disposed outside the fixed cylinder 40 and is rotatably held by the moving cylinder 41. Further, the cover cylinder 43 is disposed outside the cam cylinder 42 and is provided so as to cover the cam cylinder 42. The cover cylinder 43 is fixed to the movable cylinder 41, and the front end of the cover cylinder 43 projects forward from the front end of the movable cylinder 41. A focus ring 23 and a zoom ring 24 are disposed outside the governor tube 43, and these rings 23 and 24 are rotatably held by the cover tube 43.

  As described above, the cam cylinder 42 and the cover cylinder 43 are held by the moving cylinder 41, and the focus ring 23 and the zoom ring 24 are held by the cover cylinder 43. Therefore, when the zoom ring 24 is moved from the shortened position (position shown in FIG. 2) to the extended position (position shown in FIG. 3), these move together with the fixed cylinder 40.

  The lens unit 10 is provided with a photographic lens and a CCD 51 that captures a subject image formed by the photographic lens. The photographic lens includes an objective lens 20 that is a first group lens, a second group lens 52, a third group lens 53, and a fourth group lens 54.

  The moving cylinder 41 holds the objective lens 20 and the second group lens 52. The fixed cylinder 40 holds a shutter unit 55 having a diaphragm function, a third group lens 53, a filter unit 56, a fourth group lens 54, and a CCD 51.

  The objective lens 20 is held by a lens holding frame 58, and the lens holding frame 58 is fixed to the front surface of the movable cylinder 41. The second group lens 52 is a zoom lens and is disposed in the movable cylinder 41.

  The second group lens 52 is held by a lens holding frame 68. The lens holding frame 68 is provided with three cam followers 68a. The movable cylinder 41 is formed with three rectilinear guide grooves 41b substantially parallel to the optical axis L. These rectilinear guide grooves 41b are formed at positions corresponding to the cam followers 68a, and the cam followers 68a are inserted so that the tips of the cam followers 68a protrude. The lens holding frame 68 is prevented from rotating by these linear guide grooves 41b.

  The cam cylinder 42 is provided with a cam opening 42a that engages with the cam follower 68a, a connecting pin 42b, and an engagement groove 42c that engages with the guide shaft 40a. The cam opening 42a engages with a tip portion of a cam follower 68a that protrudes from the rectilinear guide groove 41b. Therefore, when the cam cylinder 41 is rotated, the second lens group 52 is moved to the wide end (position shown in FIG. 3) and the tele end (shown in FIG. 4) according to the displacement of the cam opening 42a in the optical axis direction. Position) along the optical axis L.

  The connection pin 42 b is inserted through an opening 43 a formed in the cover cylinder 43, and the tip end portion of the connection pin 42 b is engaged with an engagement hole 24 a formed on the inner peripheral surface of the zoom ring 24. The opening 43 a is formed along the circumferential direction. When the zoom ring 24 is rotated, the cam cylinder 42 rotates together with the zoom ring 24.

  The engaging groove 42c guides the straight movement of the cam cylinder 42 from the shortened position to the extended position, and guides the rotation of the cam cylinder 42 at the extended position.

  The shutter unit 55 is fixed to the front end portion in the fixed cylinder 40. Further, behind the shutter unit 55, a third group lens 53 and a filter unit 56 are arranged in this order, and are fixed in the fixed cylinder 40. The third group lens 53 is held by a lens holding frame 69, and the lens holding frame 69 is fixed to the fixed cylinder 40. The shutter unit 55 and the filter unit 56 are held by the lens holding frame 69.

  The fourth group lens 54 is a focus lens and is disposed behind the filter unit 56. The fourth group lens 54 is held by a lens holding frame 60. The lens holding frame 60 is screwed with the drive shaft 61 a of the focus motor 61 and is further prevented from rotating by the guide shaft 62. For this reason, when the focus motor 61 is rotationally driven, the fourth lens group 54 moves forward and backward along the optical axis L. In addition, a CCD 51 is disposed behind the fourth lens group 54 and images a subject image formed by the photographing lens.

  The AF sensor 21 is provided on the front surface of the movable cylinder 41 in a state where it is mounted on the FPC 66, and is disposed outside the objective lens 20. The FPC 66 is disposed along the outer periphery of the objective lens 20. The AF sensor 21 may be an active AF sensor or a passive AF sensor.

  A decorative plate 67 is provided on the front surface of the cover cylinder 43. An opening 67a for exposing the objective lens 20 and an opening 67b for exposing the AF sensor 21 are formed in the decorative plate 67, and the objective lens 20 and the AF sensor 21 are exposed to the outside.

  The focus ring 23 and the aperture ring 25 described above are rotated by the photographer when the focus adjustment and the aperture diameter of the aperture are manually adjusted. These rotational positions are detected by a position sensor (not shown), and the position of the fourth lens group 54 and the aperture diameter of the aperture of the shutter unit 55 are changed based on the rotational positions detected by these position sensors. Is done.

  Next, the configuration of the shutter unit 55 and the filter unit 56 will be described. As shown in FIGS. 5 and 6, the shutter unit 55 has an opening 71 formed in the center of the unit main body 70. Actuators 72 and 73 are provided on both sides of the opening 71. The actuator 72 drives a plurality of diaphragm blades (not shown) to change the opening diameter of the opening 71. As a result, the amount of photographing light incident on the light receiving surface of the CCD 51 is adjusted. The actuator 73 drives a shutter blade (not shown).

  Further, as shown in FIGS. 7 and 8, the filter unit 56 has an opening 76 in which photographing light is incident at the center of the unit main body 75. In the opening 76, an ND filter 77 for dimming photographing light is disposed. Further, a retreat space 78 for retreating the ND filter 77 from the opening 76 is formed on the outer peripheral side of the opening 76.

  The filter unit 56 covers the opening 76, that is, an insertion position where the filter unit 56 is inserted into the optical path of the photographing light (position shown in FIG. 8A) and a retreat position where the filter unit 56 is retracted from the opening 76 (shown in FIG. 8B). The ND filter 77 is moved between the position).

  Next, the arrangement position of the filter unit 56 will be described with reference to FIG. In the lens unit 10, the open aperture diameter D1 of the shutter unit 55 and the light receiving surface of the CCD 51, that is, the maximum image forming diameter D2 at the image forming position P1 of the photographing lens satisfy the condition of 0.6 <D2 / D1 <1.1. Meet. In the lens unit 10 of the present embodiment, D2 / D1 = 0.83, and as will be described later, the filter unit 56 is disposed in the vicinity of the light beam diameter minimum position P3. When D2 / D1 is 1.1 or more, the light beam diameter minimum position P3 is too close to the aperture position P2, which causes a problem that the shutter unit 55 and the filter unit 56 interfere with each other. In the case of 0.6 or less, the light beam diameter minimum position P3 is too close to the image formation position P1, so that dust adhering to the ND filter 77 appears as an image on the image formation surface.

  The filter unit 56 is disposed in the vicinity of the light beam diameter minimum position P3 where the light beam diameter D3 of the photographing light 79 is the smallest between the stop position (position of the opening 71) P2 and the imaging position P1. For this reason, since the ND filter 77 is inserted in a position where the light beam diameter D3 is small in the optical path of the photographing light 79, the outer diameter of the ND filter 77 can be reduced.

  Further, by reducing the outer diameter of the ND filter 77, the retreat space 78 of the ND filter 77 can be reduced. For this reason, the outer diameter of the lens unit 10 can be reduced by downsizing the filter unit 56.

  In the present embodiment, the light beam diameter minimum position P3 is in the vicinity of the fourth group lens 54, and the filter unit 56 is disposed between the third group lens 53 and the fourth group lens 54. As long as the position of the fourth group lens 54 does not hinder the movement of the fourth group lens 54 in the optical axis L direction, the fourth group lens 54 may be disposed behind the fourth group lens 54.

  Next, the electrical configuration of the lens unit 10 will be described. As shown in FIG. 10, the lens unit 10 is provided with a unit controller 90 that controls each part in the unit. The unit control unit 90 includes a ROM that stores a control program that controls each unit, and a RAM that temporarily stores work data. The unit controller 90 controls each part based on this control program.

  An AF sensor 21, a motor driver 91, and position sensors 92 and 93 are connected to the unit controller 90. The AF sensor 21 detects the subject distance and outputs it to the unit controller 90. The motor driver 91 is connected to the focus motor 61, and the unit controller 90 drives the focus motor 61 by controlling the motor driver 91 based on the subject distance detected by the AF sensor 21. The focus motor 61 moves the fourth lens group 54 back and forth along the optical axis L1 to adjust the focus.

  The position sensor 92 detects the rotational position of the focus ring 23, and the position sensor 93 detects the rotational position of the aperture ring 25. When the focus ring 23 is rotated, the unit controller 90 adjusts the focus by moving the fourth group lens 54 based on this rotational position. The unit controller 90 also controls the shutter unit 55 and the filter unit 56 based on this rotational position when the aperture ring 25 is rotated, and adjusts the amount of light incident on the CCD 51.

  In addition, a CCD 51 is connected to the unit controller 90 via a CCD driver 95. The unit controller 90 drives the CCD 51 by controlling the CCD driver 95. The CCD 51 converts the subject image into an electrical signal by photoelectric conversion, and acquires image data that is an analog signal.

  Further, the CCD 51 is connected to an analog signal processing unit 96 and outputs image data to the analog signal processing unit 96. The analog signal processing unit 96 is connected to the unit control unit 90 via the data bus 97 and is controlled by the unit control unit 90. The analog signal processing unit 96 performs noise removal and amplification processing on the image data and outputs the processed image data to the A / D converter 98. The A / D converter 98 converts the image data from an analog signal to a digital signal.

  The A / D converter 98 is connected to an AE / AF detection unit 99 and outputs image data converted into a digital signal. The AE / AF detection unit 99 is controlled by the unit control unit 90, detects the in-focus position where the amplitude value of the high frequency component of the image data is maximized, and outputs the AF detection value. Further, the AE / AF detection unit 99 detects an AE detection value at which the exposure is optimal, and outputs the AE detection value.

  The unit controller 90 adjusts the position of the fourth lens group 54 based on the subject distance detected by the AF sensor 21, and then based on the AF detection value acquired from the AE / AF detector 99, the fourth group The position of the lens 54 is finely adjusted. Further, the unit controller 90 controls the shutter unit 55 and the filter unit 56 based on the AE detection value, and adjusts the amount of light incident on the CCD 51.

  In addition, the serial driver 100 and the power supply control unit 101 are connected to the unit control unit 90 via the data bus 97. The unit control unit 90 controls the serial driver 100 and connects with the camera body 11 via the mount contact 102 provided on the back surface of the mount unit 22 and the mount contact 83 provided on the mount unit 30 of the camera body 11. Various operation signals and image data are transmitted and received between them.

  That is, the unit control unit 90 controls the serial driver 100 to convert the image data converted into a digital signal by the A / D converter 98 into a serial signal and output it to the camera body 11.

  The power control unit 101 is connected to the mount contact 102. The power control unit 101 is supplied with power from the camera body 11 via the mount contacts 102 and 83. The unit control unit 90 controls the power supply control unit 101 to supply power to each unit in the lens unit 10. The unit control unit 90 acquires a control signal from the control unit 90 in the camera body 11 via the mount contacts 102 and 83, and controls each unit in the unit based on the control signal.

  Next, the electrical configuration of the camera body 11 will be described. The camera body 11 is provided with a control unit 110 that controls each part in the body. The control unit 110 includes a ROM that stores a control program for controlling each unit, and a RAM that temporarily stores work data. The control unit 90 controls each unit based on this control program.

  The digital signal processing unit 111 is connected to a memory 113 via a data bus 112. The digital signal processing unit 111 acquires image data from the lens unit 10 and stores the image data in the memory 113. When the image data is stored in the memory 113, the digital signal processing unit 111 performs various image processing such as gradation conversion, white balance correction, and γ correction, YC conversion processing, and the like on the image data.

  In the shooting mode, the digital signal processing unit 111 performs simple image processing and simple YC processing on the image data before the shooting process is executed, and outputs the image data to the LCD driver 115. The control unit 110 controls the LCD driver 115 to display image data on the LCD 116 as a through image.

  Further, when the photographing process is executed, the digital signal processing unit 111 performs image processing, YC conversion processing, compression processing, and the like on the image data. The control unit 110 is connected to the media controller 117 and controls the media controller 117 to record the compressed image data on the recording medium 118.

  In the playback mode, the control unit 110 controls the media controller 117 to read out image data from the recording medium 118, and after the digital signal processing unit 111 performs decompression processing, the image data is used as a playback image. It is displayed on the LCD 116.

  In addition, an operation unit 36 and a strobe control unit 119 are connected to the control unit 110. The control unit 110 acquires various operation signals from the operation unit 36 and executes a process corresponding to each operation signal. A strobe light emitting unit 32 is connected to the strobe control unit 119. The control unit 110 controls the strobe control unit 119 to cause the strobe light emitting unit 32 to emit light.

  In addition, a serial driver 120 and a power supply control unit 121 are connected to the control unit 110 via a data bus 112. The control unit 110 controls the serial driver 120 and transmits / receives various operation signals and image data to / from the lens unit 10 via the mount contacts 102 and 103.

  The power control unit 121 is connected to the battery 122. The power control unit 121 is controlled by the control unit 110, transforms the output voltage of the battery 122 to a predetermined voltage, and supplies power to each unit in the camera body 11. The power supply control unit 121 is connected to the mount contact 103 and supplies power to the lens unit 10 via the mount contacts 102 and 103.

  In the above-described embodiment, the case where a CCD is used as an image sensor has been described as an example. However, the present invention is not limited to this.

  Furthermore, in the above-described embodiment, the lens unit including the image sensor in the lens barrel has been described as an example. However, the present invention can also be applied to a normal lens barrel that does not include the image sensor. Further, the present invention may be applied not to a lens barrel that is detachable from the camera body but to a lens barrel that is provided integrally with the camera body.

  Further, although cases have been described with the above embodiment as examples where the present invention is applied to a digital camera, the present invention is not limited to this, and the present invention may be applied to a digital video camera, a silver salt camera, or the like.

It is a perspective view which shows the structure of a lens unit and a camera main body. It is sectional drawing which shows the structure of a lens unit, and has shown the shortened state. It is sectional drawing which shows the structure of a lens unit, and has shown the state which has a 2nd group lens in a wide end. It is sectional drawing which shows the structure of a lens unit, and has shown the state which has a 2nd group lens in a tele end. It is a perspective view which shows the structure of a shutter unit. It is a front view which shows the structure of a shutter unit. It is a perspective view which shows the structure of a filter unit. It is explanatory drawing which shows the movement of ND filter. It is explanatory drawing which shows the arrangement position of a filter unit. It is a block diagram which shows the electrical structure of a lens unit and a camera main body.

Explanation of symbols

10 Lens unit 11 Camera body 51 CCD
55 Shutter unit 56 Filter unit 71 Aperture 77 ND filter P1 Imaging position P2 Aperture position P3 Minimum beam diameter D1 Open aperture diameter D2 Maximum imaging diameter D3 Beam diameter

Claims (3)

A photographic lens; an aperture that adjusts the amount of photographic light by changing an aperture diameter; and an ND filter that is detachably inserted into the optical path of the photographic light and attenuates the photographic light. In the lens barrel in which the aperture diameter D1 and the maximum imaging diameter D2 at the imaging position of the photographing lens satisfy the condition of 0.6 <D2 / D1 <1.1,
The lens barrel, wherein the ND filter is inserted in the vicinity of a light beam diameter minimum position where the light beam diameter of the photographing light is smallest between the stop and the imaging position.   A filter unit that holds the ND filter and moves the ND filter between an insertion position inserted into the optical path and a retracted position retracted from the optical path is provided in the vicinity of the minimum beam diameter position. The lens barrel according to claim 1. A lens barrel according to claim 1 or 2 and an image pickup device that is disposed in the lens barrel and picks up a subject image formed by the photographing lens, and is detachably attached to the camera body. A lens unit characterized by that.

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