JP4194314B2 - Light amount adjusting device, lens device, and imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens apparatus used in an imaging apparatus such as a video camera or a digital still camera.
[0002]
[Prior art]
As a zoom lens for a video camera, a lens composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order from the subject side is well known.
[0003]
Various lenses for digital still cameras are known regardless of the general optical type in the video. In particular, a lens for a digital still camera may be configured such that the total length is shortened by a retracting operation when shooting is not performed.
[0004]
FIGS. 7A and 7B show a lens barrel structure of a zoom lens having a general four-group lens configuration. In addition, (B) has shown the AA sectional view in (A).
[0005]
The four lens groups 201a to 201d constituting the zoom lens include a fixed front lens 201a, a variator lens group 201b that performs a zooming operation by moving along the optical axis, a fixed afocal lens 201c, And a focusing lens group 201d that moves along the optical axis to maintain and focus on the focal plane during zooming.
[0006]
Guide bars 203, 204a, and 204b are arranged in parallel with the optical axis 205, and guide and prevent rotation of the moving lens group. The DC motor 206 serves as a drive source for moving the variator lens group 201b.
[0007]
The front lens 201 a is held by the front lens barrel 202, and the variator lens group 201 b is held by the V moving ring 211. The afocal lens 201c is held by the intermediate frame 215, and the focusing lens group 201d is held by the RR moving ring 214.
[0008]
The front lens barrel 202 is positioned and fixed to the rear lens barrel 216, the guide bar 203 is positioned and supported by both the lens barrels 202 and 216, and the guide screw shaft 208 is rotatably supported. The guide screw shaft 208 is rotationally driven by the rotation of the output shaft 206 a of the DC motor 206 being transmitted via the gear train 207.
[0009]
The V moving ring 211 that holds the variator lens group 201b has a pressing spring 209 and a ball 210 that engages with a screw groove 208a formed in the guide screw shaft 208 by the force of the pressing spring 209, and is a DC motor. When the guide screw shaft 208 is rotationally driven by 206, the guide screw shaft 208 moves forward and backward in the optical axis direction while being guided and restricted by the guide bar 203.
[0010]
Guide bars 204 a and 204 b are fitted and supported on the rear barrel 216 and the intermediate frame 215 positioned on the rear barrel 216. The RR movable ring 214 can advance and retreat in the optical axis direction while being guided and restricted by the guide bars 204a and 204b.
[0011]
The RR moving ring 214 that holds the focusing lens group 201d is formed with a sleeve portion that is slidably fitted to the guide bars 204a and 204b, and the rack 213 is integrated with the RR moving ring 214 in the optical axis direction. It is assembled to become.
[0012]
The stepping motor 212 rotationally drives a lead screw 212a formed integrally with its output shaft. A rack 213 assembled to the RR moving ring 214 is engaged with the lead screw 212a. When the lead screw 212a rotates, the RR moving ring 214 moves in the optical axis direction while being guided by the guide bars 204a and 204b. To do.
[0013]
Note that a stepping motor may be used as a driving source for the variator lens group, similarly to the driving source for the focusing lens group.
[0014]
The front lens barrel 202, the intermediate frame 215, and the rear lens barrel 216 form a lens barrel main body that accommodates a lens or the like in a substantially sealed manner.
[0015]
Further, when moving the lens group holding frame using such a stepping motor, after detecting that the holding frame is positioned at one reference position in the optical axis direction using a photo interrupter or the like, the stepping motor The absolute position of the holding frame is detected by continuously counting the number of applied driving pulses.
[0016]
By the way, CCDs, which are image pickup elements used in image pickup apparatuses, are called 1/3 inch type and 1/4 inch type in consumer video cameras and have diagonal dimensions of about 6 mm and 4 mm. ing. For example, 310,000 pixels are included in this size.
[0017]
In digital still cameras, CCDs of about 1/2 inch type (diagonal 8 mm) having 2 to 3 million pixels are also used.
[0018]
In such a digital camera using a high-pixel CCD, a small print size that is widely used can ensure a comparable image quality if the conditions are the same as those of a photograph taken with a conventional film camera. It has become to.
[0019]
In such a video camera, the permissible circle of confusion is about 12-15 μm, and the digital still camera is about 7-8 μm, which is a much smaller number than the permissible circle of confusion 33-35 μm of the conventional 135 film format. This is because the diagonal dimension of the screen is much smaller than 43 mm of the 135 film format as described above. This number is expected to be smaller as the CCD pixel size is further reduced.
[0020]
From another viewpoint, the focal length for obtaining the same angle of view as that of the 135 film camera in such an imaging apparatus using a CCD is shortened due to the small image size. For example, the angle of view obtained with a standard focal length of 40 mm with a 135 film camera is 4 mm with an imaging device using a 1/4 inch CCD. For this reason, the depth of field when photographing with the same F value is extremely deep in an imaging device using a CCD, as compared with a film camera.
[0021]
On the other hand, as is well known, the depth of focus is obtained by the permissible circle of confusion diameter × F value (aperture value) on one side. For example, at F2, the depth of focus (one side) of the 135 film camera is 0. In contrast to 035 × 2 = 0.07 mm, in a 1/2 inch type imaging apparatus, the width is narrowed to 0.007 × 2 = 0.014 mm.
[0022]
As described above, even with a 1/3 inch CCD having the same diagonal size, for example, 6 mm, the number of pixels is increased from 1 million to 2 million or 3 million to increase resolution. On the other hand, various types of CCD image sensors are known, such as those that do not reduce the size of the pixels unnecessarily, but emphasize the dynamic range and sensitivity.
[0023]
In an image pickup apparatus using a CCD image pickup device as an image sensor, a method of automatically obtaining an optimum exposure by controlling the aperture opening with an aperture device so that the level of the luminance signal of the CCD is in a certain range. Is common. As a diaphragm device, an iris diaphragm using five or six diaphragm blades is known from one having two diaphragm blades having a rhombus opening shape.
[0024]
Further, it is known that when the aperture diameter is small, there is a problem that the image quality deteriorates due to diffraction. For this reason, in these imaging apparatuses, the control range of the aperture diameter is often limited to a range in which the image quality does not deteriorate or does not cause much problem. This is because the microcomputer grasps the current aperture value and does not use a smaller aperture than a predetermined F value.
[0025]
However, if the above-described restriction is applied to the usable aperture range, it becomes difficult to adjust the optimum light amount with only the aperture for a wide range of brightness of the actual field. For this reason, an ND (Neutral Density) filter is affixed integrally to the aperture blades, and the aperture opening is covered by the ND filter when the aperture diameter is reduced, so that adjustment is performed with the same aperture control (for example, open to F8). Light amount control is performed by combining a wide range of possible brightness and a variable charge accumulation time (shutter speed) of the CCD.
[0026]
As described above, the ND filter is not only one that is attached to the diaphragm blades integrally, but also has a dedicated drive source, and a method that is driven separately from the diaphragm blades to control the amount of insertion into the optical path. Are known. In this way, the ND filter and the diaphragm blades that are driven independently can independently control the aperture value and the amount of insertion of the ND filter, so that the degree of freedom of exposure control of the photographic lens or the entire imaging apparatus can be increased. .
[0027]
[Problems to be solved by the invention]
However, when the ND filter is arranged on a plane orthogonal to the optical axis, for example, the light beam reflected by the cover glass of the CCD and returned to the subject side is reflected again by the ND filter and directed to the CCD side, and the light is reflected on the CCD. May cause a ghost or flare.
[0028]
[Means for Solving the Problems]
  In order to solve the above problems, the light quantity adjusting device of the present invention is a diaphragm blade that adjusts the quantity of light passing through the optical path by opening and closing.as well asOptical filter that can be inserted into and retracted from the optical pathTheA base member that is inclined with respect to the plane perpendicular to the optical axis, is disposed between the diaphragm blade and the optical filter, and the diaphragm blade and the optical filter are operatively mounted. An aperture drive source that is arranged on the opposite side in the axial direction and opens and closes the aperture blades via the aperture drive lever, and an optical filter that is located on the opposite side of the optical axis across the base member, and optically passes through the filter drive lever. A filter driving source for inserting and retracting the filter.The inclination angle of the diaphragm blades with respect to the optical axis orthogonal plane is made smaller than the inclination angle of the optical filter with respect to the optical axis orthogonal plane.
[0029]
  in this wayDiaphragm blades andBy tilting the optical filter with respect to the plane orthogonal to the optical axis,Light control deviceThe light that came back toDiaphragm blades andIt is possible to prevent the optical filter from reflecting again toward the image sensor, and it is possible to suppress the occurrence of ghosts and flares.At this time, by making the inclination angle of the diaphragm blade with respect to the optical axis orthogonal plane smaller than the inclination angle of the optical filter with respect to the optical axis orthogonal plane, it is possible to avoid unbalance in the peripheral light amount.In addition, the diaphragm driving source is disposed on the opposite side of the optical axis direction from the diaphragm blade with the base member interposed therebetween, and the diaphragm driving source is disposed on the opposite side of the optical filter direction with respect to the optical filter with the base member interposed therebetween. The aperture driving lever and the filter driving lever can be laid out using the space between the optical filter and the optical filter, and the light quantity adjusting device can be prevented from being enlarged in the optical axis direction.
[0030]
The present invention is particularly effective when the optical filter is disposed on the image plane side with respect to the aperture blade.
[0031]
  The diaphragm blades may also be tilted with respect to the plane orthogonal to the optical axis. However, if the tilt blades are tilted so as to be parallel to the optical filter, the dimension in the optical axis direction of the light quantity adjusting device increases. Non-parallel relationship (preferably the diaphragm blades are orthogonal to the optical axisUpTo place)ByFurther, it is possible to prevent an increase in the size of the light amount adjusting device and, in turn, an increase in the size of the lens device or imaging device on which the light amount adjusting device is mounted.
[0032]
Further, when the light quantity adjusting device is configured as one unit, a guide portion for guiding the operation of the optical filter in a direction inclined with respect to the plane orthogonal to the optical axis is provided on a base member disposed between the diaphragm blade and the optical filter. It is good to provide.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
  (First embodiment)
  1 and 2 show a light amount adjusting device according to the first embodiment of the present invention. The light quantity adjusting device 9 of this embodiment includes a so-called iris-type diaphragm having six diaphragm blades.As an optical filterAnd an ND filter.
[0034]
In these drawings, reference numeral 9a denotes a base plate that serves as a base member of the light amount adjusting device 9, and an open opening 9a2 is formed at the center. Reference numeral 9d denotes a windmill ring that opens and closes six diaphragm blades, which will be described later, and is attached to the ground plane 9a so as to be rotatable around the optical axis L around the opening 9a on the subject side surface of the ground plane 9a.
[0035]
Reference numeral 9e denotes six diaphragm blades. Each diaphragm blade 9e has a hole portion 9e1 fitted with a fixed shaft portion 9a1 provided at six locations in the circumferential direction of the main plate 9a and six locations in the circumferential direction of the windmill ring 9d. An elongated hole 9e2 into which the provided drive shaft 9d1 is fitted is formed.
[0036]
  Further, a long hole portion 9d2 is formed at the tip of the arm portion formed at one place in the circumferential direction of the windmill ring 9d, and this long hole portion 9d.2Is engaged with the drive shaft portion 9c1 of the diaphragm drive lever 9c extending from the image plane side of the base plate 9a to the subject side through an arc hole 9a3 formed in the base plate 9a.
[0037]
  The aperture drive lever 9c is an aperture motor composed of a stepping motor.(Aperture drive source)It is connected to the output shaft 9b. Therefore, when the aperture motor 9b rotates and the aperture drive lever 9c rotates, the windmill ring 9d rotates, and the rotational force of the windmill ring 9d is transmitted to the six aperture blades 9e via the drive shaft portion 9d1. Therefore, the six diaphragm blades 9e rotate about the fixed shaft portion 9a1, and the aperture diameter of the diaphragm aperture formed by these six diaphragm blades 9e changes to adjust the light quantity. In addition, 9i shown in FIG. 2 is a pressing plate that prevents the diaphragm blades 9e from falling off the base plate 9a.
[0038]
On the other hand, a filter holding member 9h1 is disposed on the image plane side of the ground plane 9a. As shown in FIG. 2B, an ND filter 9h2 having a single concentration (transmittance of 32%) is attached to the lower part of the subject-side surface of the filter holding member 9h1. Further, a two-concentration ND filter 9h3 on which an optical film having two kinds of transmittances of 32% and 10% is vapor-deposited is pasted from the intermediate portion on the image plane side to the lower portion of the filter holding member 9h1. Note that the boundary between the 32% transmittance region and the 10% region in the optical film is located between the upper end of the ND filter 9h2 and the upper end of the ND filter 9h3.
[0039]
In this way, by arranging the single-concentration ND filter 9h2 and the two-concentration ND filter 9h3 on both sides in the optical axis direction with the filter holding member 9h1 interposed therebetween, as shown in FIG. 1 and FIG. The filter holding member 9h1 holds ND filters having a total of three types of transmittance: an ND area 9h7 having a transmittance of 32%, an ND area 9h8 having a transmittance of 10%, and an ND area 9h9 having a transmittance of 3%. The ND unit 9h is configured.
[0040]
Each ND area is formed so as to be inserted into the optical path in the descending order of transmittance, that is, ND area 9h7, ND area 9h8, and ND area 9h9.
[0041]
  The ND unit of this embodiment9hIs merely an example for forming two or more types of density areas. Actually, two single density filters may be combined, or only one filter having two or more types of transmittance may be pasted. Finally, the ND filter unit has two or more types of transmittance, and may be inserted into the optical path in order from the side with the higher transmittance (low density).
[0042]
  An elongate hole 9h11 is formed at the lower end of the filter holding member 9h1, and this elongate hole 9h11 has an ND motor composed of a stepping motor.(Filter drive source)ND drive lever connected to 9f output shaft(Filter drive lever)The 9g drive shaft portion 9g1 is engaged.
[0043]
  Further, elongated holes 9h12 and 9h13 are formed on the side of the filter holding member 9h1, and the elongated holes 9h12 and 9h13 each have two guide protrusions provided on the base plate 9a.(Not shown)Are engaged. For this reason, when the ND motor 9f rotates and the ND drive lever 9g rotates, the ND unit 9h reciprocates in the direction indicated by 9h14 in the figure, with respect to the optical path passing through the aperture opening formed by the aperture blade 9e. Insert and retractActionIn the inserted state, the light amount is adjusted according to the filter density.
[0044]
In the light amount adjusting device 9 of the present embodiment, the diaphragm blade 9e and the diaphragm motor 9b are arranged on the opposite sides in the optical axis direction with the ground plate 9a interposed therebetween. By doing so, the aperture drive lever 9c can be laid out using the space between the aperture blade 9e and the ND unit 9h, and the light quantity adjusting device 9 can be prevented from being enlarged in the optical axis direction. .
[0045]
The ND unit 9h and the ND motor 9f are also arranged on the opposite sides in the optical axis direction with the ground plane 9a interposed therebetween. By doing so, the ND drive lever 9g can be laid out using the space between the aperture blade 9e and the ND unit 9h, and the light quantity adjusting device 9 can be prevented from being enlarged in the optical axis direction. .
[0046]
Further, in the light amount adjusting device 9 of the present embodiment, as shown in FIG. 2A, the diaphragm blades 9e are arranged on the surface A orthogonal to the optical axis L, but the ND unit 9h has the optical axis L Is disposed parallel to a surface B inclined at an angle N ° with respect to a surface A ′ orthogonal to the surface A ′. That is, the ND unit 9h is disposed so as to be inclined by an angle N ° with respect to the optical axis orthogonal plane A ′.
[0047]
The optical axis orthogonal plane A ′ is set so as to intersect the plane B at the position of the drive shaft portion 9g1 of the ND drive lever 9g, and the ND unit 9h is not parallel to the aperture blade 9e but maintains an angle N °. It is driven in the state.
[0048]
In order to drive and guide the ND unit 9h parallel to the surface B, a guide protrusion having a guide surface having an angle N ° with respect to the optical axis orthogonal surface A ′ is provided on a portion of the base plate 9a facing the ND unit 9h. The part 12 is integrally formed.
[0049]
FIG. 3 is a view of the ground plane 9a as viewed from the direction of arrow C in FIG. 2A, and the guide protrusions 12 are formed at three locations around the opening 9a2 in the ground plane 9a. Note that the number of guide protrusions 12 is not necessarily three.
[0050]
Also, the cover 13 shown in FIG. 2A is attached to the ground plane 9a so as to be inclined at an angle N ° with respect to the plane orthogonal to the optical axis so as to sandwich the ND unit 9h with the ground plane 9a.
[0051]
For example, when the cover 13 is made of a metal plate, the guide protrusion 14 is provided at the same location as the guide protrusion 12 of the ground plate 9a by half-punching. Then, the ND unit 9h is sandwiched between the both guide projections 12 and 14.
[0052]
Therefore, the drive shaft portion 9g1 of the ND drive lever 9g rotates on the optical axis orthogonal surface A ′, but the ND unit 9h is guided in parallel to the surface B by the both guide projections 12 and 14, and the optical axis orthogonal surface A ′. Is driven at an angle N °.
[0053]
FIG. 4 shows a configuration of an image pickup apparatus such as a video camera or a digital still camera in which the light amount adjusting device described in FIGS. 1 to 3 is arranged in the photographing optical system.
[0054]
(1) is a first group (front lens) lens as a convex lens, and is held by the front lens barrel 1. This front lens barrel 1 is coupled to a fixed barrel 2 by screws 1a. Reference numeral (2) denotes a second group lens as a concave lens that moves in the optical axis direction and performs zooming, and is held by the second group holding frame 3. Reference numeral (3) denotes a third group lens as a convex lens, which is held by a third group holding frame 4 engaged and fixed to the fixed barrel 2 by an engaging portion 4a. (4) is a fourth lens group as a convex lens that moves in the optical axis direction to maintain and focus on the focal plane during zooming, and is fixed to the fourth group holding frame 5.
[0055]
The second group holding frame 3 and the fourth group holding frame 5 are each driven in the optical axis direction by a driving mechanism (not shown).
[0056]
6 is a low-pass filter, 15 is an image sensor such as a CCD or CMOS sensor, and 16 is a cover glass that covers the light receiving surface of the image sensor 15, and these are held at the rear end of the fixed barrel 2.
[0057]
Between the second group holding frame 3 and the third group holding frame 4, the light amount adjusting device 9 of the present embodiment is disposed.
[0058]
Here, FIG. 5 shows an electrical configuration of the imaging apparatus. In this figure, the components described in FIGS. 1 to 4 are given the same reference numerals as those in FIG.
[0059]
Reference numeral 132 denotes a CPU that controls the camera. A camera signal processing circuit 128 performs predetermined amplification, gamma correction, and the like on the output of the image sensor 15. The contrast signal of the video signal that has undergone these predetermined processes passes through the AE gate 129 and the AF gate 130. That is, an optimum signal extraction range for exposure determination and focusing is set in this gate in the entire screen. The size of the gate may be variable or a plurality of gates may be provided.
[0060]
Reference numeral 131 denotes an AF signal processing circuit that processes an AF signal for AF (autofocus), and generates one or a plurality of outputs related to high-frequency components of the video signal. 133 is a zoom switch operated by a photographer, and 134 is a zoom tracking memory. The zoom tracking memory 134 stores information on the focusing lens position to be set according to the subject distance and the position of the variator lens (second group lens (2)) at the time of zooming. Note that the memory in the CPU 132 may be used as the zoom tracking memory.
[0061]
For example, when the photographer operates the zoom switch 133, the CPU 132 maintains a predetermined positional relationship between the variator lens and the focusing lens (fourth group lens (4)) calculated based on information in the zoom tracking memory 134. As shown, the current position of the variator lens in the optical axis direction matches the calculated position of the variator lens, and the current position of the focus lens in the optical axis direction matches the calculated position of the focus lens. Thus, the zoom motor 10 and the focus motor 127 are driven and controlled.
[0062]
In the autofocus operation, the CPU 132 drives and controls the focus motor 127 so that the output of the AF signal processing circuit 231 shows a peak.
[0063]
  Further, in order to obtain proper exposure, the CPU 132 controls the aperture diameter by driving the aperture motor 9b based on the average value of the output of the Y signal that has passed through the AE gate 129. Further, when the average value of the output of the Y signal is high, the ND motor 9f is driven and controlled according to the degree, and the ND unit is controlled.9hIs inserted into the optical path.
[0064]
In the imaging apparatus of the present embodiment, as described above, the ND unit 9h is disposed in parallel to the surface B inclined with respect to the surface A orthogonal to the optical axis L (the ND unit 9h is a light beam). For example, the first lens group {circle around (1)}, the second lens group {circle around (2)}, the aperture opening of the light quantity adjusting device 9, the third lens group {circle around (7)}. The light from the subject that has passed through 3 and the fourth lens group (4) and directed toward the image sensor 15 is reflected by the low-pass filter 6, the cover glass 16 and the light receiving surface of the image sensor 15, and is adjusted to the light amount adjusting device 9 side. Returning to the above, even if the light is reflected again by the ND filter 9h3 or the like disposed on the image pickup surface side of the ND unit 9h, this light can be prevented from entering the image pickup device 15.
[0065]
Specifically, for example, a high-brightness subject (such as the sun) forms an image at a point 17 in FIG. 4 (here, the surface of the cover glass 16), and the light is in the direction of an arrow 18 parallel to the optical axis L. If reflected, if the ND filter is on the plane orthogonal to the optical axis, the light is reflected by the ND filter, returns in the direction opposite to the arrow 18, and enters the image sensor 15. However, as in the present embodiment, by tilting the ND unit 9h (ND filter 9h3, etc.) with respect to the optical axis orthogonal plane, the ND unit 9h is reflected in the direction indicated by the arrow 19, that is, the reflected light from the ND unit 9h is image pickup device. It is possible to guide outside the 15 light receiving screens.
[0066]
Therefore, the occurrence of flare and ghost due to the light reflected by the ND unit 9h can be suppressed.
[0067]
In the present embodiment, the basic idea for suppressing the occurrence of flare and ghost due to the light reflected by the ND unit 9h has been described. However, when the light amount adjusting device 9 is mounted on an actual imaging device, a high-luminance subject The angle and direction in which the ND unit 9h is tilted are determined depending on which location has a high probability of the presence of the ND unit 9 and the individual optical design values.
[0068]
Similarly, the diaphragm blade 9e may cause a ghost or the like due to the reflected light. Therefore, the diaphragm blade 9e may be inclined with respect to the optical axis orthogonal plane A. However, if the diaphragm blade 9e is tilted at an angle parallel to the ND unit 9h, the light amount adjusting device 9 occupies the range of the shaded portion 20 in FIG. 4, that is, the light amount adjusting device 9 in the optical axis direction. The thickness increases, and the size of the image pickup apparatus is increased in order to avoid interference with the second lens group (2). Further, if the diaphragm blade 9e is tilted too much, the positions of the upper end and the lower end of the aperture opening in the optical axis direction are greatly different, which may cause an imbalance in the peripheral light amount.
[0069]
  Therefore, the diaphragm blade 9e is inclined at an angle shallower than the angle N ° with respect to the optical axis orthogonal plane A (that is, the diaphragm blade 9e and the ND unit 9h are inclined so as to be in a non-parallel relationship).In other words, the inclination angle of the diaphragm blade 9e with respect to the optical axis orthogonal plane A is made smaller than the inclination angle of the ND unit 9h (optical filter) with respect to the optical axis orthogonal plane A.Alternatively, it is preferable to deal with the problem by arranging it on the optical axis orthogonal plane A and applying an antireflection paint as in this embodiment.
[0070]
(Second Embodiment)
In the first embodiment described above, the light amount adjusting device having an iris diaphragm using six diaphragm blades has been described. However, the present invention is also applicable to a light amount adjusting device having two blade diaphragms as shown in FIG. Can be applied.
[0071]
Of the constituent elements of the present embodiment, constituent elements common to the first embodiment are assigned the same reference numerals as in the first embodiment and are not described.
[0072]
In the present embodiment, two fixed shaft portions 9a4 'are provided on the subject side surface of the base plate 9a', and holes 9j1 formed in the two diaphragm blades 9j are fitted into these fixed shaft portions 9a4 '.
[0073]
The two aperture blades 9j are each formed with a slot 9j2, and the two aperture blades 9j are arranged so that the slots 9j2 overlap. Further, the overlapped long hole portion 9j2 is engaged with the tip of the diaphragm drive lever 9c extending from the image plane side of the base plate 9a 'through the circular hole 9a3' formed in the base plate 9a 'to the subject side. Match.
[0074]
For this reason, when the aperture motor 9b rotates and the aperture drive lever 9c rotates, the two aperture blades 9j rotate about the fixed shaft portion 9a4 'to change the area of the substantially rhomboid aperture opening.
[0075]
  Such an aperture and the ND unit described in the first embodiment9hAnd the diaphragm blade 9j is arranged on the optical axis orthogonal plane, and the ND unit9hIs arranged so as to be inclined with respect to the plane orthogonal to the optical axis, as in the first embodiment, the ND unit9hIt is possible to prevent the occurrence of ghosts and the like due to the reflected light at.
[0076]
Furthermore, the present invention can also be applied to a light amount adjustment device having a diaphragm of a type that is linearly driven in a direction in which two blades are separated or approach each other, which is most commonly used as a diaphragm of a video camera or the like. it can.
[0077]
Note that the configuration of the light amount adjustment device described in each of the above embodiments is merely an example, and can be changed as appropriate according to the size and other requirements required for the imaging lens on which the light amount adjustment device is mounted and the imaging device. .
[0078]
In each of the above-described embodiments, the light amount adjusting device in which the diaphragm blade and the ND filter are driven independently has been described. However, in the present invention, the ND filter is attached to the diaphragm blade and the both are integrally driven. The present invention can also be applied to a light amount adjusting device. In this case, the ND filter may be attached at an angle to the diaphragm blades arranged on the plane orthogonal to the optical axis.
[0079]
In each of the above embodiments, the case where an ND filter is used as an optical filter has been described. However, the present invention can also be applied to a light amount adjusting device including an optical filter other than the ND filter.
[0080]
Furthermore, in each of the above-described embodiments, the imaging device including the light amount adjusting device has been described. However, the present invention can also be applied to a light amount adjusting device mounted on an interchangeable photographing lens device.
[0081]
【The invention's effect】
  As explained above, according to the present invention,Diaphragm blades andSince the optical filter is inclined with respect to the plane orthogonal to the optical axis, it is reflected by the image sensor, etc.Light control deviceThe light that came back toDiaphragm blades andIt can be prevented from being reflected again toward the image sensor by the optical filter, and generation of ghost and flare can be suppressed.Further, by making the inclination angle of the diaphragm blade with respect to the optical axis orthogonal plane smaller than the inclination angle of the optical filter with respect to the optical axis orthogonal plane, it is possible to avoid unbalance in the peripheral light amount.In addition, the diaphragm driving source is disposed on the opposite side of the optical axis direction from the diaphragm blade with the base member interposed therebetween, and the diaphragm driving source is disposed on the opposite side of the optical filter direction with respect to the optical filter with the base member interposed therebetween. The aperture driving lever and the filter driving lever can be laid out using the space between the optical filter and the optical filter, and the light quantity adjusting device can be prevented from being enlarged in the optical axis direction.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a light amount adjusting device according to a first embodiment of the present invention.
FIG. 2 is a side view of the light amount adjusting device and an enlarged view of an ND unit.
FIG. 3 is a rear view of the light amount adjusting device.
FIG. 4 is a cross-sectional view of an image pickup apparatus equipped with the light amount adjusting device.
FIG. 5 is a block diagram showing an electric circuit configuration of the imaging apparatus.
FIG. 6 is an exploded perspective view of a light amount adjusting device according to a second embodiment of the present invention.
FIG. 7 is a cross-sectional view of a conventional imaging device.
[Explanation of symbols]
1 Front lens barrel
2 Fixed lens barrel
6 Low-pass filter
9, 9 'Light intensity adjustment device
9a, 9a 'ground plate
9e, 9j Aperture blade
9h ND unit
9h2, 9h3 ND filter
12, 14 Guide protrusion
15 Image sensor
16 Cover glass
A, A 'Optical axis orthogonal plane
B Surface inclined with respect to the optical axis orthogonal plane
▲ 1 ▼ ~ ▲ 4 ▼ Lens

Claims (4)

A diaphragm blade that adjusts the amount of light that passes through the optical path by opening and closing, and an optical filter that is inserted into and retracted from the optical path, and the diaphragm blade and the optical filter are inclined with respect to the plane orthogonal to the optical axis. A light quantity adjusting device,
A base member disposed between the aperture blade and the optical filter, to which the aperture blade and the optical filter are operatively attached;
An aperture drive source disposed on the opposite side to the aperture blade in the optical axis direction across the base member, and opening and closing the aperture blade via an aperture drive lever;
Wherein the said optical filter across the base member is disposed on the optical axis opposite possess a filter drive source for inserting and retracting operation of the optical filter via the filter drive lever,
The light quantity adjusting device , wherein an inclination angle of the diaphragm blade with respect to the optical axis orthogonal plane is smaller than an inclination angle of the optical filter with respect to the optical axis orthogonal plane .   The light quantity adjusting device according to claim 1, wherein the optical filter is disposed on the image plane side with respect to the aperture blade. Lens apparatus characterized by having an imaging optical system including a light amount adjustment device according to claim 1 or 2. A photographing optical system including a light amount adjustment device according to claim 1 or 2, an imaging apparatus characterized by having an imaging means for imaging an object image formed by the photographing optical system.

Images