JP2006119214A - Lens barrel and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a lens barrel which has an actuator. <P>SOLUTION: The lens barrel comprises light quantity control units (13, 14, 15, 16, 17, 20) which change the size of an opening and control light quantity, an actuator (12) for driving an optical element in the lens barrel and a first lens member (3) which is arranged on the nearest position to the light quantity control units on the image side of the light quantity control units and is adjacent to the actuator in the optical axis orthogonal direction, wherein the outer peripheral part (3a) on the actuator side on the first lens member is nearer to an optical axis than the outer peripheral part on the opposite side to the actuator side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lens barrel and an optical device having a light amount adjustment unit that adjusts a light amount by changing the size of an opening.

  Conventionally, a lens barrel in which optical members such as a diaphragm unit, a focus lens, and a zoom lens are incorporated has been proposed (see, for example, Patent Document 1). These optical members are driven by the driving force of the actuator.

As another conventional example, there has been proposed a lens device in which a part of a circular lens is D-cut and a space formed by the D-cut is used as a retreat area in which the inner converter lens retreats (for example, a patent) Reference 2).
Japanese Patent Laid-Open No. 2002-169074 (FIG. 7) Japanese Patent Laid-Open No. 07-199019 (FIG. 5, paragraph 0013)

  However, in the above-described conventional example, it is difficult to downsize the lens barrel in the radial direction because the actuator of the optical member is disposed outside the circular lens when viewed in the optical axis direction.

  In order to solve the above problems, a lens device according to the present invention as one aspect includes a light amount adjustment unit that adjusts the amount of light by changing the size of an opening, and an actuator for driving an optical element in a lens barrel. And a first lens member that is disposed closest to the light amount adjustment unit on the image side of the light amount adjustment unit and is adjacent to the actuator in the direction perpendicular to the optical axis, and the outer peripheral portion on the actuator side of the first lens member is It is characterized by being closer to the optical axis than the outer peripheral portion on the side opposite to the actuator side.

  According to the present invention, since the outer peripheral portion on the actuator side of the first lens member is closer to the optical axis than the outer peripheral portion on the side opposite to the actuator side, the actuator can be disposed close to the optical axis. As a result, the lens barrel and the optical device having the lens barrel can be reduced in size.

Embodiments of the present invention will be described below with reference to the drawings.

  First, a lens barrel according to a first embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a cross-sectional view including the optical axis direction of the lens barrel, and FIG. 2 is a CC cross-sectional view of the lens barrel of FIG. The lens barrel of this embodiment is attached to a camera body (optical device) (not shown).

  Reference numeral 1 denotes a first lens unit, and reference numeral 2 denotes a second lens unit that moves in the optical axis direction by a zooming operation, and is disposed on the image side of the first lens unit 1.

  Reference numeral 3 denotes a third lens unit (first lens member) which has a circular shape when viewed in the optical axis direction, and a part of the outer periphery thereof is retracted to the optical axis side, and details thereof will be described later.

  Reference numeral 4 denotes a fourth lens unit that moves in the optical axis direction during zooming and focusing operations. Reference numeral 5 denotes a first lens holding frame for holding the first lens unit 1, and 6 denotes a second lens holding frame for holding the second lens unit. Reference numeral 7 denotes a third lens holding frame for holding the third lens unit 3, and 8 denotes a fourth lens holding frame for holding the fourth lens unit 4.

Reference numeral 9 denotes a fixed cylinder, which holds the first lens holding frame 5 and holds a low-pass filter 18 and an image sensor 19 (for example, a CCD sensor or a CMOS image sensor).
The fixed cylinder 9 and the first lens holding frame 5 hold the third lens holding frame 7. Therefore, the third lens holding frame 7 does not move in the optical axis direction.

  Reference numeral 10 denotes a first guide bar extending in the optical axis direction, one end of which is held by the fixed cylinder 9 and the other end is held by the first lens holding frame 5.

  The second lens holding frame 6 is formed with a first sleeve 6a having a through hole extending in the optical axis direction, and the first guide bar 10 is formed in the hole of the first sleeve 6a. Are engaged. Due to the engaging action of the first sleeve 6 a and the first guide bar 10, the second lens holding frame 6 is guided in the optical axis direction.

  Reference numeral 11 denotes a second guide bar extending in the optical axis direction, one end of which is held by the fixed cylinder 9 and the other end is held by the first lens holding frame 5. The fourth lens holding frame 8 is formed with a second sleeve 8a having a through hole extending in the optical axis direction. The second guide bar 11 is formed in the hole of the second sleeve 8a. Are engaged. Due to the engaging action of the second sleeve 8 a and the second guide bar 11, the fourth lens holding frame 8 is guided in the optical axis direction.

  The second lens holding frame 6 and the fourth lens holding frame 8 are driven by a zoom actuator and a focus actuator (not shown).

  A diaphragm actuator 12 is held by the diaphragm base plate 13 and is adjacent to the third lens unit 3 in the direction perpendicular to the optical axis as shown in FIG. The aperture actuator 12 is composed of a stepping motor having a rotor, a magnet and the like.

  15 is a first diaphragm blade, 16 is a second diaphragm blade disposed below the first diaphragm blade 15, and these diaphragm blades 15 and 16 are held by the diaphragm base plate 13. And is driven in response to the driving force from the aperture actuator 12.

  The second diaphragm blade 16 holds an ND (Nutral Density) filter 17. The aperture base plate 13 is formed with a fixed opening 13a (opening) through which the photographing light flux passes.

  An arm 20 is fixed to the rotary shaft 12 a of the aperture actuator 12, and convex portions 20 a and 20 b are formed at the tip of the arm 20. These convex portions 20a and 20b are engaged with the first and second aperture blades 15 and 16, respectively. Reference numeral 14 denotes a pressing plate that prevents the first and second aperture blades 15 and 16 from moving and removing in the optical axis direction.

  The diaphragm base plate 13, the holding plate 14, the first diaphragm blade 15, the second diaphragm blade 16, the ND filter 17, and the arm 20 constitute a light amount adjustment unit 224 (see FIG. 3). The light amount adjustment unit 224 is disposed on the image side of the third lens unit 3 and is disposed closer to the third lens unit 3 than the fourth lens unit 4.

  In the above-described configuration, when the aperture actuator 12 is driven, the rotational force of the rotary shaft 12a is transmitted to the arm 20, so that the first and second aperture blades 15 and 16 connected to the arm 20 are connected to the aperture base plate 13. It advances and retreats with respect to the fixed opening 12a. As a result, the opening area of the fixed opening 13a changes, and the amount of light passing through the imaging light flux passing through the fixed opening 13a changes.

  Next, the third lens unit 3 will be described in detail.

  The third lens unit 3 has a circular shape with a radius R when viewed in the optical axis direction. However, a retraction shape portion 3a that retreats closer to the optical axis side than the other outer peripheral portions is provided on the outer peripheral portion on the actuator 12 side. Is formed. As shown in FIG. 2, when the straight line passing through the optical axis is a straight line S, the retracting shape portion 3a is formed on a D-cut line T passing through the lower side by a length B therefrom, and has a fixed opening. It is located closer to the optical axis than the outer periphery of the portion 13a.

  When the second diaphragm blade 16 is in the open state, the end portion 17a on the optical axis side of the ND filter 17 is disposed closer to the optical axis side than the retracting shape portion 3a, and the retracting shape portion 3a has a fixed opening portion. It is arranged on the optical axis side with respect to 13a.

  As described above, in the present embodiment, the retraction shape portion 3a retracted to the optical axis side is provided on the outer peripheral portion of the third lens unit 3 on the aperture actuator 12 side, and the aperture actuator 12 is moved to the optical axis side by the retracted amount. It can be arranged in. Thereby, the lens barrel can be downsized in the radial direction.

  That is, since the dimension from the optical axis to the aperture actuator 12 is set to be shorter by the length RB than in the case where the third lens unit 3 is not D-cut, the lens barrel and the lens barrel are used. The optical device used can be reduced in size.

  In addition, the ND filter 17 enters the fixed opening 13a in the open state. However, even in the conventional configuration, the ND filter remains in the optical path in the open aperture state. Since the ND filter generally has a light transmission amount of 20% or less, even if a part of the fixed opening is covered in the open state, the amount of light passing through the ND filter is the total amount of light passing through the fixed opening. Among them, the ratio is small.

  In this embodiment, since the D-cut range of the third lens unit 3 is covered with the ND filter 17 in the fully open state, the T number in the open state can be obtained as compared with the case where the D-cut is not performed. There is almost no need to change.

  FIG. 3 is a functional block diagram of a camera (optical device) to which the lens barrel of the present embodiment is attached. In the figure, the same components as those in FIG.

  A zoom driving unit 222 drives the second lens holding frame 6 and includes a zoom actuator. A focus drive unit 223 drives the fourth lens holding frame 8 and includes a focus actuator.

  225 is a zoom encoder and 227 is a focus encoder. These encoders 225 and 227 detect the absolute positions of the second lens holding frame 6 and the fourth lens holding frame 8 in the optical axis direction, respectively.

  When a DC motor is used as the zoom actuator, an absolute position encoder such as a volume or a magnetic encoder may be used.

  On the other hand, when a stepping motor is used as a zoom actuator, a method is generally employed in which the second lens holding frame 6 is arranged at a reference position and the number of operation pulses input to the stepping motor is continuously counted.

An aperture encoder 226 is known in which a Hall element is arranged inside a motor that constitutes a light quantity adjustment unit to detect a rotational positional relationship between the rotor and the stator.
A camera signal processing circuit 228 performs predetermined amplification processing, gamma correction, and the like on the output signal of the image sensor 19. The contrast signal of the video signal that has undergone these predetermined processes is input to the AE gate 229 and the AF gate 230.

  That is, an optimum signal extraction range for determining exposure and focusing is set by this gate. Although the size of the gate may be variable or may be provided, a detailed description is omitted here.

  Reference numeral 231 denotes an AF signal processing circuit which generates one or a plurality of outputs related to high frequency components of the video signal. Reference numeral 233 denotes a zoom switch, and reference numeral 234 denotes a zoom tracking memory, which stores position information of the fourth lens holding frame 8 to be taken according to the distance between the subject and the second lens holding frame 6 at the time of zooming. Reference numeral 232 denotes a control circuit that controls the entire camera. The zoom tracking memory 234 may be incorporated in the control circuit 232.

  In the above-described configuration, for example, when the photographer operates the zoom switch 233, the control circuit 232 calculates the second lens holding frame 6 and the fourth lens holding frame calculated based on information read from the zoom tracking memory 234. The zoom drive unit 222 and the focusing drive unit 223 are driven and controlled so that the predetermined positional relationship (optical condition) of 8 is maintained.

  Accordingly, the second lens holding frame 6 and the fourth lens holding frame 8 are driven so as to satisfy the optical conditions.

  In the autofocus operation, the control circuit 232 controls the drive of the focus drive unit 223 so that the output signal of the AF signal processing circuit 231 has a peak. Further, in order to obtain an appropriate exposure, the control circuit 232 makes the average value of the output of the Y signal that has passed through the AE gate 229 become a predetermined value, and so that the output of the aperture encoder 226 becomes the predetermined value. The light amount adjustment unit 224 is driven and controlled to control the opening diameter of the fixed opening 13a.

  In this embodiment, the lens-integrated camera (optical device) has been described. However, the present invention can also be applied to an interchangeable lens barrel that can be attached to and detached from the camera.

  Further, although the aperture actuator 12 is a stepping motor, a vibration type motor that has an electro-mechanical energy conversion element and excites vibration by a frequency signal may be used.

  FIG. 4 shows a second embodiment of the present invention. In this example, a linear actuator for driving the fourth lens holding frame 8 (second lens member) is arranged in the D-cut range. In addition, the same component as Example 1 attaches | subjects the same code | symbol, and abbreviate | omits description.

  30 is a coil integrally attached to the fourth lens holding frame 8, 31, 32 and 33 are magnets integrally fixed to the third lens holding frame 7 or the fixed cylinder 9, a lower yoke and an upper yoke, respectively. It is. The coil 30, the magnet 31, the lower yoke 32 and the upper yoke 33 constitute a linear actuator 35.

  In the present embodiment, the retraction shape portion 3a retracted to the optical axis side is provided on the outer peripheral portion of the third lens unit 3 on the linear actuator 35 side, and the linear actuator 35 is disposed on the optical axis side by the retracted amount. Yes. Thereby, a lens barrel can be reduced in size in the radial direction.

Sectional view in the optical axis direction of the lens barrel in the first embodiment of the present invention. CC sectional view of the lens barrel of FIG. Functional block diagram of the camera Sectional view in the optical axis direction of the lens barrel in the second embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens unit 2 2nd lens unit 3 3rd lens unit 4 4th lens unit 5 1st lens holding frame 6 2nd lens holding frame 6a 1st sleeve 7 3rd lens holding frame 8 Fourth lens holding frame 8a Second sleeve 9 Fixed cylinder 10 First guide bar 11 Second guide bar 12 Aperture actuator 13 Aperture base plate 14 Holding plate 15 First aperture blade 16 Second aperture blade 17 ND Filter 18 Low-pass filter 19 Image sensor 20 Arm 30 Coil 31 Magnet 32 Lower yoke 33 Upper yoke 35 Linear actuator

Claims (6)

In the lens barrel,
A light intensity adjustment unit that adjusts the light intensity by changing the size of the opening;
An actuator for driving an optical element in the lens barrel;
A first lens member that is disposed closest to the light amount adjustment unit on the image side of the light amount adjustment unit and is adjacent to the actuator in the direction perpendicular to the optical axis;
The lens barrel characterized in that the outer peripheral portion on the actuator side of the first lens member is closer to the optical axis than the outer peripheral portion on the opposite side to the actuator side. The light amount adjustment unit has an ND filter that covers a part of the opening in an open state,
In the open state, the outer peripheral portion on the actuator side of the first lens member is farther from the optical axis than the end portion on the optical axis side of the ND filter and closer to the optical axis than the outer periphery of the opening. The lens barrel according to claim 1.   The lens barrel according to claim 1, wherein the first lens member is fixed in an optical axis direction.   The lens barrel according to claim 1, wherein the actuator drives the light amount adjustment unit.   4. The lens barrel according to claim 1, wherein the actuator drives a second lens member. 5.   An optical apparatus comprising the lens barrel according to any one of claims 1 to 5.

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