JP2003315871A - Nd driver and image pickup device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter driver which arranges filters such as ND filter and color filter in a diaphragm opening without lowering the MTF of an optical system and controls the quantity of passage light appropriately and to provide an optical appliance having the filter driver. <P>SOLUTION: The ND driver is provided with a plurality of the ND filters having n pieces of different concentration regions (wherein, n is an integer of ≥2) and a driving means for driving in the direction of separating a plurality of the ND filters from each other or bringing the same near to each other. Therein, the n pieces of concentration regions of the ND filters are formed in such a manner that the transmitted light quantity of the diaphragm opening part is changed symmetrically with respect to the center as the concentration regions are made to approach with each other. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device such as a video camera or a digital still camera, and an ND drive device for adjusting the amount of light transmitted through a photographing lens used therein by using an aperture and an ND filter, and an optical device having the same. .

[0002]

2. Description of the Related Art Zoom lenses are often used in optical devices such as video cameras and digital still cameras.
As a zoom lens, for example, from the subject side, positive,
There is a four-group zoom lens having four lens groups of negative, positive and positive refractive power. Of course, zoom lenses having various lens configurations other than this lens configuration are known.

In addition, various photographing lenses for digital still cameras have been proposed in which the total length is shortened by a collapsing operation when photographing is not performed.

Here, a zoom lens having an optical type commonly used in the above-mentioned video camera will be described.

FIG. 7 and FIG. 8 are cross-sectional views of a main part of a lens barrel structure of a four-group zoom lens composed of the four most general lens groups described above. 201a-201d are four lens groups which comprise a zoom lens. The lens group 201a is a fixed front lens group, and the lens group 201b is an optical axis 205.
A lens group 201c is a fixed afocal lens group, and a lens group 201d is a focal plane at the time of magnification change by moving along the optical axis 205. This is a forcing lens group for maintaining and focusing.

In FIG. 7 and FIG. 8, the guide bars 203 and 204a, 204b are arranged parallel to the optical axis 205,
It guides the moving lens group and detents. The DC motor 206 serves as a drive source for moving the variator lens group 201b. Although a DC motor is shown as a drive source for the variator lens group 201b in this figure, a step motor may be used similarly to a drive source for moving a focusing lens group 201d described later.

The variator lens group 201b is a holding frame 2
It is held at 11. This holding frame 211 is a pressing spring 2.
09 and the force of the pressure spring 209, the ball 21 that engages with the screw groove 208a formed in the screw rod 208.
It has 0 and. Therefore, the motor 206 outputs the screw rod 20 through the output shaft 206a and the gear train 207.
By rotating 8 the holding frame 211 moves in the optical axis direction along the guide bar 203.

The focusing lens group 201d is held by a holding frame 214. A screw member 213 is assembled in the vicinity of a sleeve portion (a portion that engages with a guide bar to form a guide) of the holding frame 214 so as to be integrated with the holding frame 214 in the optical axis direction. The output shaft 212a of the reference numeral 213 is rotated by rotating the step motor 212, and the male screw portion and the screw member 213 formed on the output shaft 212a are formed so that the screw portion or the rack portion is interlocked with this rotation. Then, the holding frame 214
Can be moved in the optical axis 205 direction along the guide bars 204a and 204b. The detailed configuration of the connecting portion between the holding frame 214 and the screw member 213 is disclosed in, for example, Japanese Patent Laid-Open Publication No. 4-136806.
215 is a holding frame for the lens group 201c, 216 is a fixed barrel,
220 is a mount part.

As described above, this step motor 21
The interlocking mechanism by 2 may be configured as a variator drive mechanism.

Further, when the lens group is moved by using such a step motor, a photo interrupter (not shown) and a moving frame are integrally provided to detect the absolute position of the moving lens group in the optical axis direction. If one reference position in the optical axis direction of the moving frame can be detected by the provided light shielding wall, after arranging the holding frame at this reference position, it is possible to continuously count the number of driving steps given to the step motor thereafter. This makes it possible to configure a position detecting means for detecting the absolute position of the holding frame.

FIG. 9 is a block diagram of the drive system shown in FIGS.

In FIG. 9, the components having the same reference numerals shown in FIGS. 7 and 8 have the same function.

Reference numeral 221 denotes a solid-state image pickup device such as CCD, and 222.
Is a drive source of the variator lens group 201b, and includes the motor 206 of FIGS. 7 and 8, a gear train interlocking with the motor 206, a screw rod 208, and the like. Alternatively, FIG.
Similar to the driving of the focusing lens group 201d in FIG. 8, it is composed of a step motor and the like. Reference numeral 223 denotes a driving source of the focusing lens group 201d, which includes a step motor, an output shaft of which a male screw is formed, a holding frame, and a screw member 213 which is integrated in the optical axis direction.

Reference numeral 224 is a diaphragm drive source. 225 is a zoom encoder and 227 is a focus encoder. These encoders 225 and 227 are the variator lens 201b and the focusing lens 20, respectively.
The absolute position of 1d in the optical axis direction is detected. When a DC motor is used as the variator drive source as shown in FIGS. 7 and 8, an absolute position encoder such as a volume is used (not shown in FIGS. 7 and 8). Alternatively, a magnetic type may be used.

Further, when a step motor is used as a drive source, it is general to arrange the holding frame at the reference position as described above and then continuously count the number of operation pulses input to the step motor. .

Reference numeral 226 is a diaphragm encoder, and a system is known in which a Hall element is arranged inside a meter which is a diaphragm driving source to detect a rotational positional relationship between a rotor and a stator.

Reference numeral 228 is a camera signal processing circuit, which is a CC
Predetermined amplification and gamma correction are applied to the output signal from D221. The contrast signal of the video signal subjected to the predetermined processing is the AE gate 229 and the AF gate 23.
Pass 0. That is, the optimum signal extraction range for determining the exposure and focusing is set by this gate from within the entire screen. The size of the gate may be variable or a plurality of gates may be provided, but the details are not described here for simplicity.

Reference numeral 231 denotes an AF signal processing circuit for AF (autofocus), which generates one or a plurality of outputs relating to the high frequency components of the video signal. Reference numeral 233 is a zoom switch, and 234 is a zoom tracking memory, which stores information on the focusing lens position to be taken according to the subject distance and the variator lens position during zooming. The zoom tracking memory is a CPU
Memory within 232 may be used. 232 is a CPU.

For example, depending on the photographer, the zoom switch 233
When is operated, the CPU 232 causes the variator 201 calculated based on the information in the zoom tracking memory 234.
b so that a predetermined positional relationship between the focusing lens 201d and the focusing lens 201d is maintained, the current absolute position of the variator 201b, which is the detection result from the zoom encoder 225, and the calculated position where the variator 201b should be, the focus position. The current absolute position of the focus lens 201d in the optical axis direction, which is the detection result of the coater 227, and the calculated position of the focus lens 201d,
The zoom drive source 222 and the focusing drive source 223 are drive-controlled such that

In the autofocus operation, the output signal from the AF signal processing circuit 231 has a peak value C
The PU 232 drives and controls the focusing drive source 223.

Further, in order to obtain proper exposure, the CPU 232
Controls the aperture diameter by controlling the aperture encoder 226 so that the average value of the Y signal output that has passed through the AE gate 229 becomes a predetermined value and the aperture drive source 224 so that the output becomes the predetermined value. To do.

The CCD image pickup device 221 is called a 1/3 inch type or a 1/4 inch type in a consumer video camera, and its diagonal size is about 6 mm or 4 mm, which is becoming the mainstream. This size has, for example, 310,000 pixels. In addition, it is 1/2 for digital still cameras.
200 ~ 3 with inch type (diagonal 8mm) CCD
Something that has, 000,000 pixels is also used.

In a digital camera using such a high pixel CCD, a photograph taken by a conventional film camera is used in a small print size which is widely used.
If the conditions are met, it is becoming possible to secure comparable image quality.

In such a video camera, the permissible circle of confusion diameter is about 12 to 15 μm, and the digital still camera is about 7 to 8 μm, which is much smaller than the permissible circle of confusion 33 to 35 μm of the conventional 135 film format. It will be a number. This is because the diagonal size of the screen is much smaller than the 43 mm of the 135 film format as described above. It is expected that this number will become smaller as the pixel size of the CCD becomes smaller.

From another point of view, the focal length for obtaining the same angle of view is shorter than that of a 135 film camera and an image pickup device using such a CCD because the image size is small. For example, the angle of view obtained with a standard focal length of 40 mm with a 135 film camera is 1 /
An image pickup device using a 4-inch CCD has a size of 4 mm.
Therefore, the depth of field when shooting with the same F value (F number) becomes extremely deep in the image pickup apparatus using these CCDs, as compared with the film camera.

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, and therefore the depth of focus (one side) of a 135 film camera is F2, for example. While 0.035 × 2 = 0.07 mm, the half-inch type image pickup device has 0.007 × 2.
It becomes as narrow as 0.014 mm.

As described above, the diagonal dimension is the same, for example, 6 m.
Even with a 1/3 inch CCD of m, the number of pixels is increased from 1 million to 2 million to increase the resolution, and on the other hand, the size of the pixels is unnecessarily small. However, various specifications are also known for CCD image pickup devices, such as those that emphasize dynamic range and sensitivity.

Next, a light quantity adjusting method will be described. In an image pickup device such as a video camera or a digital still camera that uses an image pickup device such as a CCD as an image sensor, the aperture diameter is controlled by a diaphragm device so that the level of the CCD luminance signal is within a certain range. Automatically getting the best exposure. Known iris diaphragms include iris diaphragms having five or six diaphragm blades having two diaphragm blades having a rhombus-shaped aperture.

Further, when the aperture diameter of the diaphragm becomes small, there arises a problem that the image quality is deteriorated due to diffraction. Therefore, in these image pickup apparatuses, it is general practice to limit the control range of the aperture diameter to a range in which image quality deterioration does not occur or is not likely to occur. In this, the microcomputer grasps the current aperture value, and the aperture smaller than the predetermined F value is not used.

However, if such a restriction is applied to the usable diaphragm range, it becomes difficult to adjust the optimum light quantity only by the diaphragm for a wide range of brightness of an actual field. For this reason, an ND filter is integrally attached to the aperture blades, and the aperture area is covered by the ND filter when the aperture diameter becomes smaller, so that the brightness that can be adjusted by the same aperture control (for example, open to F8) is adjusted. Widen the range, C
The light amount control is performed in combination with making the charge storage time (shutter speed) of the CD variable.

The ND filter is not limited to the one that is integrally attached to the diaphragm blades as described above, but it also has a dedicated drive source, and the amount of protrusion into the optical path (in the diaphragm aperture diameter) separately from the diaphragm. A method of controlling is also known.

Among them, the one in which the ND filter is integrally attached to the blade has no problem in a state where the ND filter covers the entire aperture of the diaphragm, but until reaching the ND filter, only a part of the aperture is ND. There is a filter. Further, this causes a slight deviation in the image forming position between the light beam that has passed through the ND filter and the light beam that has not passed through the ND filter.
It may also affect TF.

Further, there is a region where the amount of transmitted light is limited by the transparent portion and the ND in the opening, and if the area of the transparent portion is small, the diffraction will occur as if it were generated with a small aperture value. Image deterioration may occur due to. For this reason, it is general to reduce the influence of this diffraction as much as possible by configuring the ND filter attached to the diaphragm blades to have a plurality of densities instead of one density. .

The same applies to N independently of the diaphragm blade.
The same applies when driving the D filter. Whether the ND filter driven independently is completely retracted from the opening,
Alternatively, it may be a fully inserted state, but an intermediate state may be used in some cases. In this case, similarly, the MTF is deteriorated due to the diffraction and the deviation of the optical path length. In order to prevent this, it is known to prepare an ND filter also having a plurality of density regions.

Not only two diaphragm blades but also a so-called iris diaphragm is well known.

FIG. 10 is a schematic view showing the structure of a conventional general diaphragm unit having two diaphragm blades.

In FIG. 10, reference numeral 513a is a meter which is a drive source. The output shaft 515 of the meter 513a is integrally provided with a lever 514 (cross-hatched parts).
Is attached. The lever 514 has a convex portion 513 on its tip.
e1, 513d1. Blades 513d and 513e
Each have a hole that fits into the tip projection of the lever 514 described above and forms an opening 516.

Although the diaphragm is open in FIG. 10, the blade 513d moves upward and the blade 513e moves downward by rotating the lever 514 counterclockwise from here, and the opening diameter of the opening 516 becomes small. It is a thing. Each of the wings 513d, 513e has a guide groove portion for moving in the vertical direction, and the guide groove portion is provided with a convex portion 513f2, 513f1 integrally with the base member 513f.
The moving direction is defined by fitting the long groove portions of the blades 513d and 513e into the 3f1 and 513f2. An ND filter 501 is attached to the blade 513d. In this figure, the ND filter 501 is described in a single color, but an example in which an ND filter divided into a plurality of density regions is attached is also known.

FIG. 11 is a schematic diagram of the configuration of the ND drive device 601 when the ND filter is driven independently of the diaphragm device. In FIG. 11, 631 is a drive source, 632 is its output shaft, 633 is a lever component integrated with the output shaft 632, and has a convex portion 634 at its tip. 637 is N
The D filter holder is configured to rotate around the rotation shaft 636. Reference numeral 635 denotes an elongated hole portion provided at an end portion of the holder 637, which is fitted with the convex portion 634. As a result, when the drive source 631 rotates, the ND filter holder 637 rotates about the rotation shaft 636. The holder 637 has a size (aperture diameter 60) that covers a predetermined aperture opening diameter (here, assumed to be open) 605.
5 ') ND filters 608 and 609 are attached. Here, ND filters of two types of density are provided. That is, the ND filter section 638 having a low density (high transmittance) and the ND filter section 639 having a high density (low transmittance).

Reference numeral 605 denotes an open diaphragm opening, from which diaphragm blades 602 driven by a diaphragm driving source (not shown),
A diaphragm aperture 604 is formed by 603. In this example, since it consists of two diaphragm blades 602 and 603,
The aperture shape of the aperture opening 604 is rhombic. 641
Is the optical axis. That is, by rotating the ND filter drive source in the direction of the arrow in the figure, the ND filter is configured to cover the aperture opening diameter 604 in order from the one with the highest transmittance.

In this example, two ND filters 638,
639 covers the aperture open diameter 605, but there is also known an example in which the ND filter is inserted in a state where the aperture is smaller for the purpose of downsizing the whole. In this case, the CPU provided in the imaging device is configured to drive and control the ND drive device when the aperture is equal to or smaller than a predetermined aperture diameter while detecting the state of the diaphragm.

Also, in this example, the example in which the ND filter moves by the rotation drive has been described, but the invention is not limited to this.
It is also possible that the ND filter is driven linearly.

In FIG. 12, the ND filter NDF1 has ND filters NDF1 to NDF3 having three types of density,
FIG. 7 is a schematic diagram assuming a case where an opening Sa having an opening diameter S1 is covered. In this case, from the state where the ND filter is not applied to the opening Sa, the third density N having the lowest transmittance is obtained.
By the time D filter NDF3 covers the opening, 3 × (S
It is necessary to drive the stroke of 1).

The taking lens generally has a required resolution (M) determined by the pixel pitch of the CCD in which the taking lens is used.
Designed and manufactured so that TF performance) is obtained. Also, C
It has an effective image circle determined by the size of the CD.

Shooting is roughly classified into moving picture shooting and still picture shooting. Of these, the most general way to appreciate the result of shooting a movie is to play it back on a television. For viewing on television, for example, NTS
A television signal defined in a format called C is used. As is well known, in the case of NTSC, it is composed of field images every 1/60 seconds, and a frame image is obtained by two continuous field images. Also, the definition of the image at this time is inevitably determined from the number of scanning lines determined by the television format.

Therefore, as described above, even if the CCD has a large number of pixels, it becomes impossible to reproduce the luminance information and the color information from all the pixels on the television screen without directly processing them. Multi-pixel CCD
In order to create a television signal from the image pickup apparatus using, the image is converted (reduced) by performing some reduction signal processing.

That is, the video signal information included in the original image cannot be reproduced as it is, and the image quality converted (corresponding to the television signal) is reproduced on the television. That is, a normal video camera that reproduces with a television signal has 10
When using a CCD of 0,000 pixels or 2 million pixels, there is a lot of information of the original image, so there is a side where an image can be obtained,
It is not possible to fully utilize the large number of pixels. However, an actual video camera using these multi-pixel CCDs generally has a function as a still camera at the same time.

The recording medium is not a video tape, but a memory card for recording a still image in the same image pickup device is generally used. In such still image recording, the higher the number of pixels of the CCD, the higher the resolution of the image that can be recorded. That is, in an image pickup device using a multi-pixel CCD, a high-definition image that can be picked up by the multi-pixel CCD may not be maintained due to reduction processing when shooting a moving image.
A high-definition image obtained by the multi-pixel CCD can be recorded during still image shooting.

Although the above is assumed to be reproduced on a television, it may be possible to handle a moving image on a personal computer. In such a case, a moving image with a higher image quality than that reproduced on a television is considered. May be treated.

Further, various types of television signal formats have been proposed from the currently popular ones, which assume higher image quality, and some have been put into practical use.

[0051]

A CCD as described above.
The reduction of the pixel pitch and the expansion of the number of pixels are remarkable,
Along with this, when a method in which an ND filter is attached to diaphragm blades is used as a conventional mainstream light amount adjustment method, MTF deterioration due to areas where the ND filter is present and areas where the ND filter is not present, and Due to the difference in transmittance, when the area of a portion having high transmittance becomes small, diffraction occurs due to a state of a small diaphragm, and deterioration factors such as MTF deterioration cannot be ignored.

Similarly, even when an ND drive device is provided separately from the diaphragm device, in the method shown in FIGS. 11 and 12, when the single density covers the entire area of the aperture, the MTF is increased.
However, the deterioration occurs similarly in the middle stage, and as can be seen from the examples of FIGS. 11 and 12, if the predetermined opening is covered with a plurality of densities, the device becomes large. It also had the disadvantage of becoming

The present invention provides a filter driving device and an optical device having the filter driving device, in which a filter such as an ND filter color filter is arranged in the aperture opening and the amount of passing light can be appropriately controlled without lowering the MTF of the optical system. For the purpose of providing.

In addition, according to the present invention, by driving a plurality of ND filters having two or more different density regions in a direction in which they are separated from or close to each other, it is possible to adjust the amount of light transmitted through the aperture opening. A filter driving device capable of appropriately controlling the amount of light passing through the aperture opening without lowering the MTF of the optical system by at least one of the different density regions covering the predetermined opening substantially uniformly. And an optical device having the same.

[0055]

According to a first aspect of the present invention, there is provided an ND drive device, wherein a plurality of ND filters having n (n is an integer of 2 or more) different density regions and a plurality of ND filters are narrowed down. Drive means for driving in a direction away from or close to each other on the aperture, and the density regions of the n ND filters move the amount of light transmitted through the aperture opening with respect to the center thereof as they approach each other. It is characterized in that it is formed so as to change symmetrically.

According to a second aspect of the present invention, in the first aspect of the present invention, the density regions of the plurality of ND filters may have a state of covering the aperture opening substantially uniformly n times in the process of bringing them close to each other. It is characterized by being formed in.

According to a third aspect of the present invention, in the first or second aspect of the present invention, when the aperture diameter of the aperture opening is D, one of the n density regions of the ND filter is in the driving direction. It is characterized in that the length is approximately D / n.

The invention of claim 4 is characterized in that, in the invention of claim 1, 2 or 3, the plurality of ND filters are two ND filters.

According to a fifth aspect of the present invention, in the invention of the fourth aspect, the density of the n different density regions is the same when the density regions of one type of the two ND filters are overlapped with each other. It is characterized in that it substantially matches the density of the density area of.

An image pickup apparatus according to a sixth aspect of the present invention is characterized by including the ND drive apparatus according to any one of the first to fifth aspects.

The invention of claim 7 is characterized in that, in the invention of claim 6, an aperture shutter device is provided.

According to the image pickup apparatus of the present invention, N has a plurality of diaphragm blades and n (n is an integer of 2 or more) different density regions provided integrally with each of the plurality of diaphragm blades.
A D filter and a driving unit that drives the plurality of blades in a direction in which they are spaced apart from or close to each other to adjust the amount of light that passes through the diaphragm aperture, and the density regions of the n ND filters are arranged close to each other. It is characterized in that it is formed so that the transmitted light amount of the aperture opening changes symmetrically with respect to the center thereof as the distance increases.

According to a ninth aspect of the present invention, in the eighth aspect of the invention, the driving means drives the plurality of diaphragm blades to adjust the amount of light transmitted through the aperture in a state where the diaphragm is open, and a plurality of ND filters are provided. It is characterized in that the maximum density obtained by overlapping further drives in a direction covering the aperture opening, thereby reducing the aperture diameter.

According to a tenth aspect of the invention, in the eighth or ninth aspect of the invention, when a still image is photographed, a substantially single density is used in a state of covering the entire aperture of the diaphragm aperture.

The invention of claim 11 relates to claim 8, 9 or 10.
The invention is characterized in that the density regions of the plurality of ND filters are formed such that a state of covering the aperture opening substantially uniformly exists n times in the process of bringing them closer to each other.

According to a twelfth aspect of the present invention, in the eighth, ninth, tenth or eleventh aspect of the invention, when the aperture diameter of the aperture opening is D, one of the n density regions of the ND filter is The length in the driving direction is approximately D / n.

The thirteenth aspect of the present invention is the invention according to any one of the eighth to twelfth aspects, wherein the plurality of diaphragm blades are two diaphragm blades, and the density of the n different density regions is the two It is characterized in that the density when one type of density region of two ND filters provided on one diaphragm blade is overlapped is substantially the same as the density of another type of density region.

[0068]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of essential parts of a first embodiment of a filter driving device of the present invention. FIG. 1 shows a relative drive of ND filters 2 and 3 having a plurality of density regions with respect to an aperture (aperture aperture) 1 of an optical system (from FIG.
(B) and FIG. 1 (C) in order, driving up to FIG. 1 (G) in the direction of approaching, driving in the opposite direction driving away from the opening 1
The density distribution by the ND filters 2 and 3 obtained inside is shown. Here, the opening 1 has a predetermined opening diameter, and corresponds to an opening diameter such as F (F number) 4 as an example of opening or being determined by a diaphragm device (not shown). When determined by the diaphragm device, in addition to the circular shape shown in the figure, a rhombus formed by a two-blade diaphragm or a polygonal opening formed by an iris diaphragm may be formed.

Although the case where the ND filter is used as the filter is shown, an optical filter such as a color filter or a color temperature filter may be used.

The ND filters 2 and 3 have the same size and the same density area and density, and have high transmittance (low density) areas 2a and 3a on the side close to the opening 1 as shown in FIG. However, adjacent to that region, there are regions 2b and 3b having lower transmittance (higher concentration). here,
The filter density obtained by stacking two filters having the density of the regions 2a and 3a coincides with the density of the region 2b or 3b.

In the state shown in FIG. 1A, the two ND filters 2 and 3 are retracted from the opening 1, so that the N
D filters 2 and 3 are in a state where they are not applied at all. From this state, FIG. 1B and FIG.
When the ND filters 2 and 3 are driven to approach each other until (G), the regions 2a and 3a start to be applied to a part of the opening 1 in the state of FIG. 1 (B). At this time, since a part of the filters 2 and 3 exists in a part of the opening 1, a light beam that has passed through a part with the filter and a light beam that has passed through a part that does not exist are mixed, and thus the MTF of the optical system Some deterioration factors occur.

Further, even if the thickness of the ND filters 2 and 3 is 0, due to the presence of the portions having different densities (the transparent portion and the portions 2a and 3a of the filters 2 and 3) in the opening. However, the MTF is slightly deteriorated. However, this deterioration reduces the cause of the one-sided blur occurring in the conventional ND drive device as shown in FIGS. 10 and 11, for example.

That is, in the system shown in FIGS. 10 and 11, the ND filter 501 exists only in the lower part and not in the upper part when viewed from the optical axis, which is not symmetrical. For this reason, the MTF often varies in the vertical direction of the screen. In the state of FIG. 1B of this embodiment, such a difference in MTF does not occur in the vertical direction.

After that, two more ND filters 2 and 3 are used.
When is driven in the direction of approaching, the state shifts from FIG. 1 (C) to FIG. 1 (G). At this time, FIG.
In (E) and FIG. 1 (F), N existing in the opening 1 as well.
Although the D filters 2 and 3 have mixed portions having different thicknesses, the concentration distribution is symmetrical, and the deterioration of the total MTF is significantly improved as compared with the conventional case.

1 (C), 1 (E) and 1 (G) show a state in which the inside of the opening 1 is covered with a uniform transmittance. Figure 1
In (C), the regions 2a and 3a respectively divide the region into two and cover the opening. In FIG. 1E, the density is determined by the region 2a and the region 3a overlapping at the center of the opening including the optical axis 1a, and the regions 2b and 3b occupy the upper and lower peripheral portions. In order to make the state of FIG. 1 (E) substantially uniform density, the density relationship as described above is defined in the areas 2a and 3b and the areas 2b and 3b. Further, FIG. 1G is obtained by overlapping the regions 2b and 3a in the upper half of the optical axis 1a and the regions 2a and 3b in the lower half.

Actually, due to the dimensional accuracy and density variation of this ND filter, and the mechanism of driving this ND filter which will be described later, FIG.
In the states of FIGS. 1 (E) and 1 (G), a region out of the uniform density is also generated, but here, including a state in which the substantially uniform region covers substantially the entire area, FIG. 1 (C), FIG. E), Figure 1
It is characterized by (G).

FIG. 2 is a cross-sectional view of the essential parts of Embodiment 1 of the drive device for driving the two ND filters 2 and 3 shown in FIG. Since this is an example of a configuration similar to the diaphragm device that drives two blades shown in FIG. 10, parts having the same functions as in FIG. 10 are given the same numbers.

In FIG. 2, the aperture shape of the aperture blades 513d and 513e forming the aperture 516 of the aperture is determined to be rectangular. And in this rectangular part, 2
ND filters 517 and 518 having one density region are integrally provided. This is generally a blade 513d,
ND filters 518 and 517 are bonded to 513e. Here, 516 is an opening having a diameter larger than the opening diameter.
In this embodiment, the size that covers the opening is shown.
If the diameter of the opening to be covered can be reduced to, for example, F4, the drive amount of the blade can be reduced, so that the overall size of the apparatus can be reduced.

Here, in the vertical direction of FIG. 2, as shown in FIG. 1, the distance corresponding to the radius of the opening 516 is configured to substantially match the vertical dimensions of the ND filters 517 and 518. Alternatively, considering the component accuracy, it is better to set the diameter slightly larger than this diameter.

The ND filter 51 attached in this way
7 and 518, by driving the driving unit, FIG.
The state described in (G) is maintained.

Assuming that the predetermined aperture diameter of the diaphragm is D, the lengths in the driving direction of the density regions having different n are approximately D.
/ N. It is possible to efficiently increase the number of densities while covering the openings with a single concentration.

FIG. 3 is a block diagram of the image pickup apparatus of the present embodiment, and the same components as those in the conventional block diagram shown in FIG. 9 are designated by the same reference numerals.

In the first embodiment, the ND filter driving device 701 having the structure as described with reference to FIGS. 1 and 2 is arranged in the taking lens independently of the diaphragm device. N
The state of D (at which position of the transition as shown in FIG. 1) is detected by the ND encoder 702. Here, as well known in the diaphragm device, as this detection method, a method of arranging a Hall element in the drive meter and detecting the rotational position of the rotor magnet can be applied.

In addition, when a step motor is used as a drive source, a method of continuously counting the number of drive pulses input from a reference position (for example, a rotation end) can be applied. In addition to this, it is possible to apply a method such as adding a rotary volume. Reference numeral 703 denotes an ND drive source, which uses a meter, a step motor, or the like, as described above.

Here, other, for example, an ultrasonic motor may be used. When the photographer performs a photographing operation, the operation content is transmitted by the CPU 232. Reference numeral 704 is a moving image trigger switch. Reference numeral 705 denotes a shutter operation for a still image. Reference numeral 706 denotes a recording definition selection switch, for example, when recording a still image, whether to record a high-definition image using a large number of memories for comparison, or to reduce the definition to reduce the memory capacity. A selection is made. This choice is not mandatory.

Reference numeral 707 denotes a shooting mode selection switch. Here, it is assumed that selection of moving image shooting or still image shooting is performed. Reference numeral 711 is a reduction processing circuit. It is assumed that the CCD used in this image pickup device has, for example, one million pixels or more, and the image is reduced from this to create a television signal. The reduced image is recorded or displayed in the moving image recording 709 and the electronic viewfinder 710. A still image recording unit 708 performs recording from the highest definition obtained by the multi-pixel CCD to the image reduced in image to the resolution selected by the user.

In such an image pickup apparatus, as shown in FIGS.
The exposure control is performed by using the ND driving device 701 as described above in combination with the diaphragm device and the shutter device (control of the charge accumulation time to the CCD).

For example, when shooting a moving image, the aperture is driven from the full aperture to the predetermined aperture diameter, and if the exposure is still overexposed, the ND drive device 701 is moved from the state of FIG. The filter is driven in the direction in which it approaches. If the exposure is still overexposure even after reaching FIG. 1E, if the aperture is driven toward the small aperture side again and the aperture is driven up to a limit F value where image deterioration due to diffraction is unacceptable, if the exposure is overexposed. The shutter speed is further increased from this state.

Further, when a still image is photographed, in particular, when MTF deterioration due to a diffraction phenomenon is prevented and a high image quality is photographed,
As the state of the ND filter, it is possible to limit some usable states. For example, in FIG. 1, FIG. 1A, FIG. 1C, FIG. 1E, and FIG.
In each of the states, since the inside of the opening has a uniform transmittance, a step in the transmittance occurs at a portion inside the opening, and as described above,
This will not cause deterioration of the image due to diffraction or unbalance of the image plane illuminance at the four corners of the screen.

Furthermore, among these, FIG. 1 (A) and FIG.
In each state of (C) and FIG. 1 (G), since the thickness of the ND filter in the opening is also uniform, the MTF does not deteriorate due to the difference in thickness depending on the part.

As described above, between (A) to (G) in FIG. 1, the state having an allowable MTF is stored in the ROM in the CPU 232 in FIG. Alternatively, depending on the state of the recording definition selected by the selection switch 706, only the stored state is used for photographing.

As described above, this embodiment has at least 2
By having ND filters having a plurality of diaphragm blades and having n (n is an integer of 2 or more) different density regions integrally with the diaphragm blades, and driving the diaphragm blades in a direction in which they are separated or close to each other, The amount of light transmitted through the aperture is adjusted when the aperture is open. At this time, the maximum density obtained by overlapping the two ND filters is further driven from the state in which the aperture is fully covered, so that in the open state, the ND density is first used up to the maximum concentration to perform exposure control, and then in the same direction. The aperture control is performed by driving.

When still images are shot, a state in which a single density covers the entire opening is used, and when shooting moving images, other states are also used for shooting. It can be done, and continuous exposure control is performed during movie shooting.

Next, a second embodiment of the present invention will be described.

In FIG. 1, assuming that the diameter of the opening 1 is D,
The ND filters 2 and 3 also have a dimension of a length D in the moving direction, and the two densities 2a and 2b are divided into two equal widths.
An example having (3a, 3b) is given. In practice, in consideration of manufacturing error and the like, the width of the ND filters 2 and 3 in FIG. 1 is made larger than the opening diameter D, and the dimension in the moving direction of the dense area is made slightly longer. Good. Here, the density obtained when two ND filters with the lower density are stacked is the density on the dark side.

In the first embodiment, the density of the ND filter is
Whereas the length D is divided into two areas, the length D is divided into three areas, and in the third embodiment, the area is divided into three areas. It should be noted that there may be three or more areas.

FIG. 4 is an explanatory view of the essential parts of the second embodiment of the present invention. In FIG. 4, the ND filters 2 and 3 have three density regions 2a, 2b, 2c (3a, 3b, 3), respectively.
c). Here, the density obtained by superimposing the two densities of the region 2a (3a) is substantially the same as the density of the region 2b (3b), and it is obtained by superimposing the regions 2a (3a) and 2b (3b) one by one. The density is substantially the same as the area c.
It should be noted that the term “substantially coincident” means that, for example, if the MTF deteriorates only about 10% or less from the state of FIG. It is a waste.

Similar to FIG. 1, the state shown in FIG.
Up to the state of (G), the ND filters 2 and 3 are driven in a direction in which the ND filters 2 and 3 approach each other.

By increasing the concentration region in this manner as compared with the embodiment of FIG. 1, the difference in concentration occupied in the opening can be made smaller than that shown in FIG. 1, which is advantageous for MTF.

Further, as in the first embodiment, while observing the deterioration amount of the MTF, for example, at the time of still image shooting, the states of FIG. 4 (A), FIG. 4 (C), FIG. 4 (E), and FIG. 4 (G). Can be used.

Further, from FIG. 1, the final density of FIG. 4 (G) can be set high.

The area of the ND filter having 3 densities in the 3 areas shown in the second embodiment may be increased by 3 or more. For example, the same effect can be obtained by uniformly dividing the same dimension in the longitudinal direction as the opening diameter D into n to form an ND filter having a region of n concentration. An ND filter having 2-3 regions of 2-3 densities is desirable in consideration of prevention of image deterioration due to diffraction.

Next, a third embodiment of the present invention will be described.

FIG. 5 and FIG. 6 are schematic views of the main part of the diaphragm drive device and diaphragm according to the third embodiment of the present invention. In the third embodiment,
After the two ND filters are brought close to each other by the ND drive device so as to overlap with each other, the two ND filters are further moved in the extension direction (closer to the ND filter) to have a diaphragm effect (to reduce the aperture).

FIG. 5 shows a diaphragm device integrally having this ND drive mechanism, and those having the same part numbers as the ND drive device of FIG. 2 have the same functions. In FIG. 5, three areas 2a to 2c are shown.
ND filters having different densities (3a to 3c) are attached to the blades, but here, the outermost areas 2d and 3d of the areas 2c and 3c having the highest density are roof-shaped (triangular shape). ). When the meter is driven in the direction in which the two blades (or the ND filter) come close to each other from the open state (state of FIG. 5), FIG. 6 (A) to FIG. 6 (C)
It changes like. In FIGS. 6 (A) and 6 (B), the diaphragm has an open aperture, but in FIG. 6 (C), the diaphragm is narrowed. By driving closer than in FIG. 6C, the opening is finally closed.

In the first and second embodiments, a diaphragm device or a shutter device also serving as a diaphragm may be separately provided, but in the third embodiment, the diaphragm shutter can also serve as a diaphragm shutter. However, if necessary, a shutter device will be provided separately.

In the third embodiment, in the case of the diaphragm, the exposure control is first performed by the ND filter section from the opening, and then the opening of the diaphragm is controlled. Since the stroke of the blade is 3 to 4 times that of an ordinary diaphragm device, the size of the device is increased in both the vertical and horizontal directions in the drawing. In conventional lens units, this increase in size is difficult to tolerate. However, with the miniaturization of CCDs and the increase in the number of pixels as described above, the aperture diameter when the aperture of the video camera is opened is reduced from a conventional diameter of, for example, 6 to 8 mm to 4 mm or less. ing. Therefore, even an integrated ND mechanism and diaphragm device can be made relatively small.

In each of the above embodiments, a color temperature filter or a color filter may be used instead of the ND filter. At this time, instead of the areas having a plurality of densities, one having a change in color temperature or one having a plurality of areas having a change in color density may be used.

As described above, according to each of the embodiments of the present invention, it is possible to have a plurality of states in which a predetermined aperture of the diaphragm is covered with a substantially single density, that is, a state in which deterioration of MTF does not occur. High-quality shooting can be performed by shooting only in a wide aperture.

Also, in other diaphragm states, the difference in transmittance due to the site in the aperture is relatively small, and the density distribution is symmetrical in the moving direction of the ND filter as seen from the optical axis. It is possible to suppress the shading (unbalanced peripheral light intensity at the four corners of the screen).

Since the aperture size has been reduced with the recent miniaturization of CCDs, the ND drive device and the aperture device can be easily integrated so that the intermediate diffraction image does not deteriorate. A light quantity adjusting device can be achieved.

[0112]

According to the present invention, a filter driving device capable of appropriately controlling the amount of passing light by disposing a filter such as an ND filter color filter in the aperture opening without lowering the MTF of the optical system. It is possible to achieve an optical device having

In addition, according to the present invention, a plurality of, for example, two ND filters having two or more different density regions are driven in a direction in which they are separated from or close to each other.
The amount of light transmitted through the aperture opening can be adjusted, and one or more of the different density regions cover the predetermined aperture substantially uniformly, so that the light passes through the aperture without reducing the MTF of the optical system. It is possible to achieve a filter driving device that can appropriately control the amount of light and an optical apparatus including the filter driving device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a diaphragm aperture according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a main part of the diaphragm device according to the first embodiment of the present invention.

FIG. 3 is a block configuration diagram according to the first embodiment of the present invention.

FIG. 4 is an explanatory view of a diaphragm aperture according to the second embodiment of the present invention.

FIG. 5 is a schematic view of a main part of a diaphragm device according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of a diaphragm aperture according to a third embodiment of the present invention.

FIG. 7 is an explanatory view of a conventional lens barrel.

FIG. 8 is an explanatory view of a conventional lens barrel.

FIG. 9 is a block configuration diagram of a conventional diaphragm drive device.

FIG. 10 is a schematic view of a main part of a conventional diaphragm drive device.

FIG. 11 is a schematic view of a main part of a conventional diaphragm drive device.

FIG. 12 is an explanatory view of a diaphragm aperture of a conventional diaphragm driving device.

[Explanation of symbols]

1 aperture 2,3 ND filter 2a, 2b, 3a, 3b area 513d, 513e diaphragm blades 517, 518 ND filter 516 opening 701 ND drive device 702 ND encoder 703 ND drive source

Claims (13)

[Claims] 1. A plurality of ND filters having n (n is an integer of 2 or more) different density regions, and the plurality of ND filters.
A driving means for driving the filters in a direction in which they are separated from each other or close to each other on the aperture opening, and the density regions of the n ND filters are arranged so that the transmitted light amount of the aperture opening is changed as they approach each other. An ND drive device, which is formed so as to change symmetrically with respect to a center. 2. The density regions of the plurality of ND filters are formed such that a state of covering the aperture opening substantially uniformly exists n times in the process of bringing them closer to each other. Item 1. The ND drive device according to item 1. 3. When the aperture diameter of the aperture opening is D, one of the n density regions of the ND filter has a driving direction length of about D / n. The ND drive device according to claim 1 or 2. 4. The plurality of ND filters are two NDs.
It is a filter, Claim 1, 2 or 3 characterized by the above-mentioned.
ND drive device. 5. The densities of the n different density regions are:
The ND drive device according to claim 4, wherein the densities when the density regions of one type of the two ND filters are overlapped are substantially the same as the densities of the density regions of the other type. 6. An imaging device comprising the ND drive device according to claim 1. Description: 7. The image pickup device according to claim 6, further comprising an aperture shutter device. 8. A plurality of diaphragm blades, an ND filter having n (n is an integer of 2 or more) different density regions provided integrally with each of the plurality of diaphragm blades, and the plurality of blades. And driving means for driving the diaphragms so that they are spaced apart from or close to each other and adjusting the amount of light passing through the aperture opening. The density regions of the n ND filters are the amount of transmitted light through the aperture opening as they approach each other. Is formed so as to change symmetrically with respect to the center thereof. 9. The maximum density obtained by overlapping a plurality of ND filters is adjusted by driving the plurality of diaphragm blades by the driving unit to adjust the amount of light transmitted through the opening in the diaphragm open state. 9. The image pickup apparatus according to claim 8, wherein the diaphragm diameter is reduced by further driving in the covered direction. 10. The image pickup apparatus according to claim 8, wherein a substantially single density is used in a state of covering the entire aperture of the diaphragm aperture when a still image is captured. 11. The density regions of the plurality of ND filters are formed such that a state of covering the aperture opening substantially uniformly exists n times in the process of bringing them closer to each other. Item 9. The image pickup device according to item 8, 9 or 10. 12. When the aperture diameter of the aperture opening is D, one of the n density regions of the ND filter has a driving direction length of about D / n. The image pickup apparatus according to claim 8, 9, 10, or 11. 13. The plurality of diaphragm blades are two diaphragm blades, and the density of the n different density areas is obtained by overlapping one density area of two ND filters provided on the two diaphragm blades. 13. The combined density is substantially the same as the density of another type of density region.
The imaging device according to any one of 1.