JP2012042565A - Lens barrel, imaging device and optical adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel having a bending optical system such as a prism for changing optical paths from a first optical axis to a second optical axis, in which influences of a mounting error of an optical member along the second optical axis are reduced to increase the accuracy.SOLUTION: The lens barrel includes an optical member which is movably disposed along a first optical axis (A), an optical member 7 which is disposed and optically adjustable along a second optical axis B, a prism which changes the optical path from the optical axis (A) to the optical axis (B), and optical members 3, 4 disposed along the optical axis (B). Upon optically adjusting the optical member 7, light from a light source 51 passes through an adjustment chart 52, the optical members 3, 4 and 7, and an opening 6a formed in a holding member 6 of the optical member 7, and exits through an opening of the lens barrel to the outside. An adjusting tool lens 53 and a sensor 54 detect the light exiting to the outside of the lens barrel. After adjusting a position of the optical member 7 in a direction perpendicular to the optical axis (B) based on the evaluation results, the optical member 7 is fixed to the holding member 6.

Description

  The present invention relates to optical adjustment of a lens barrel using a bending optical system.

  2. Description of the Related Art An imaging device that changes an optical axis direction with a bending optical system such as a prism to form an image is known. A lens barrel having a plurality of lens groups and a prism or the like is configured such that the first lens group takes in an incident light beam from the subject side along the first optical axis, and the light beam transmitted through the first lens group is transmitted by the prism. The optical path is changed in the direction of the second optical axis by bending. The second optical axis intersects the first optical axis at a predetermined angle, for example, 90 degrees, and the imaging element receives the light beam that has passed through the second lens group along the second optical axis.

  In the lens barrel disclosed in Patent Document 1, first, the second lens group that moves along the second optical axis is retracted to the image sensor side, and then into the space formed along the first optical axis. The moving first lens group is retracted.

In general, there is known a lens barrel in which a lens group or a single lens constituting the lens group is optically adjustable in order to absorb an assembly error or a dimensional error of the lens barrel.
In the lens barrel disclosed in Patent Document 2, first, a lens group along the second optical axis is attached to the lens barrel, and after the lens barrel is installed in the imaging apparatus main body, the lens group along the first optical axis. Can be adjusted.

  In the prism inspection method disclosed in Patent Document 3, the prism holding member that holds the prism is provided with an intermediate wall at a position facing the reflecting surface of the prism, and the position of the reflecting surface of the prism is provided by providing an opening in the intermediate wall. Can be measured.

JP 2006-259665A JP 2009-145691 A JP 2009-104168 A

However, the conventional technique has the following problems concerning the optical adjustment related to the second lens group.
In the technique disclosed in Patent Document 2, optical adjustment is performed using a bending optical system including a prism. For this reason, there has been a problem that the mounting error of the lens group along the second optical axis includes a tilting component of the optical axis due to the mounting error of the prism.
Further, Patent Document 3 discloses only an inspection of a prism mounting error, and there is a problem that optical adjustment that absorbs the mounting error of the lens group along the second optical axis cannot be performed.

  Therefore, an object of the present invention relates to an optical member along the second optical axis in a lens barrel having a bending optical system such as a prism for changing the optical path from the first optical axis to the second optical axis. The purpose is to increase the accuracy by reducing the influence of mounting errors.

  In order to solve the above problems, a lens barrel according to the present invention includes a first optical member disposed on the first optical axis and a second optically adjustable second lens disposed on the second optical axis. A lens barrel including an optical member, a bending optical element that changes an optical path from the first optical axis to the second optical axis, and a third optical member that is disposed on the second optical axis When the second optical member is disposed on the second optical axis and optical adjustment of the optical member is performed, light from a light source used for optical adjustment is applied to the second optical axis. Along the third optical member and the second optical member, and passes through the lens barrel so as to be emitted to the outside from the opening.

  According to the present invention, since the optical adjustment can be performed only with the optical member disposed on the second optical axis, it is possible to reduce the influence of the mounting error of the optical member and increase the accuracy.

FIG. 4 is a cross-sectional view of the main part showing a state at a wide angle position as a configuration example of the lens barrel according to the embodiment of the present invention in combination with FIGS. It is principal part sectional drawing which shows the state which has a lens-barrel in a telephoto position. It is principal part sectional drawing which shows the state which has a lens-barrel in a storage position. FIG. 4 is a development view of an inner peripheral surface of a fixed cylinder 62 shown in FIGS. 1 to 3. It is a perspective view which shows the structural example of the holding member of a prism, and its support mechanism. It is a perspective view which shows the structural example of the part which concerns on the optical adjustment of an adjustment lens. It is a schematic diagram explaining the optical adjustment of an adjustment lens. It is a disassembled perspective view which shows the movable part containing a 1st group lens and a 2nd group lens, and a lens-barrel base.

Hereinafter, an example of an imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a lens barrel mounted on an imaging apparatus such as a digital camera will be described as an example.
FIG. 1 is a main part cross-sectional view showing a state in which the lens barrel of the imaging apparatus according to the present embodiment is at the WIDE position (wide-angle position). The lens barrel shown in FIG. 1 includes a first lens group 10 and a second lens group 20 (first optical member) disposed on a first optical axis indicated by the A axis. The lens barrel includes an adjustment lens 7 (second optical member), a third lens group 30 and a fourth lens group 40 (third optical member) disposed on the second optical axis indicated by the B axis. Prepare. The driving mechanism of the first lens group 10 and the second lens group 20 includes a cam cylinder 61 and a rectilinear guide cylinder 63 held by a fixed cylinder 62.

The first lens group 10 includes a first group lens 1 and a second group lens 2. The first group lens 1 is held by the first group lens barrel 11, and the second group lens 2 is held by the second group lens barrel 21. The light beam incident through the first group lens 1 and the second group lens 2 undergoes an optical path change from the first optical axis A to the second optical axis B by the prism 5. That is, the light passing through the first group lens 1 and the second group lens 2 is bent in the direction of the optical axis B that intersects the optical axis A at an angle of about 90 °, and the third lens group 30 and the fourth lens group. 40, guided to the image sensor 9 through the optical filter 8.
The prism 5 as an example of a bending optical element is held by a holding member 6 and can be moved along the second optical axis B by a driving mechanism (not shown). The holding member 6 holds the adjustment lens 7 on the optical axis B on the emission surface side of the prism 5 so as to be optically adjustable. The holding member 6 is formed with an opening 6a penetrating along the second optical axis B. The opening 6a formed on the side opposite to the adjustment lens 7 is a prism cover 15 which is a light shielding member. Is shielded from light. The light whose optical path has been changed by the prism 5 passes through the adjustment lens 7, and then reaches the image sensor 9 through the third lens group 30, the fourth lens group 40 and the optical filter 8 on the second optical axis B. .
The third lens group 30 includes a shutter (see the shutter driving unit 30a in FIGS. 6 and 8) attached to the front base plate 32, and a third group lens 3 held by the rear base plate 34. The rear base plate 34 and the front base plate 32 is connected by screw fastening or the like. The third lens group 30 performs a zooming operation by moving along the second optical axis B by a third lens group motor (not shown). In the fourth lens group 40, the fourth group lens holder 41 is held by the fourth group lens 4. When the fourth group lens 4 is moved along the second optical axis B by a fourth lens group motor (not shown), a zooming operation and a focusing operation are performed. The optical filter 8 has a low-pass filter function for blocking light with a high spatial frequency and a function for blocking infrared light.

  FIG. 2 is a cross-sectional view of the main part showing a state where the lens barrel is in the TELE position (telephoto position). In this state, when compared with the state shown in FIG. 1, the first lens group 10 advances toward the subject along the first optical axis A, and the second lens group 20 extends along the first optical axis A. And then stops at a position approaching the prism 5. The third lens group 30 moves toward the prism 5 along the second optical axis B, and stops at a position close to the prism 5. The fourth lens group 40 moves toward the image sensor 9 along the second optical axis B and stops at a position close to the element.

  FIG. 3 is a cross-sectional view of the main part showing a state where the lens barrel is in the SINK position (storage position). In this state, the prism 5, the third lens group 30, and the fourth lens group 40 have moved along the second optical axis B to positions that do not interfere with each other on the image sensor 9 side. As a result, a storage space for the first lens group 10 and the second lens group 20 is formed in the lens barrel, and these lens groups are retracted along the optical axis A and positioned in the storage space and fixed. It can be stored in the cylinder 62.

  FIG. 4 is a developed view of the inner peripheral surface of the fixed cylinder 62. A plurality of cam grooves 62 a are formed on the inner peripheral surface of the fixed cylinder 62. Cam pins (not shown) provided on the outer periphery of the cam cylinder 61 are cam-engaged with these cam grooves 62a. The cam groove 62a has a straight groove and an inclined groove, and reference numerals 62c to 62e denote cam pin engagement positions, the details of which will be described later. The rectangular cutout portion 62b is formed so as not to interfere with the fixed cylinder 62 when the prism 5 moves along the optical axis B toward the image sensor 9 side.

A gear portion (not shown) is formed on the outer peripheral portion of the cam barrel 61, and the cam barrel 61 is rotationally driven around the first optical axis A as a driving force is transmitted from a motor (not shown). . At this time, the cam cylinder 61 advances and retreats along the first optical axis A by the cam engagement between the cam groove 62 a of the fixed cylinder 62 and the cam pin of the cam cylinder 61. A first group cam groove and a second group cam groove (not shown) are formed on the inner peripheral portion of the cam cylinder 61.
The rectilinear guide tube 63 is disposed on the inner peripheral side of the cam tube 61, can rotate integrally with the cam tube 61, and can move in the direction of the first optical axis A. As shown in FIGS. 1 to 3, a part of the first group barrel 11 is disposed between the cam barrel 61 and the rectilinear guide barrel 63, and a cam pin provided on the outer peripheral portion thereof is a first group cam groove of the cam barrel 61. (Not shown) is cam-engaged. Further, a rectilinear groove (not shown) extending along the direction of the first optical axis A is formed in the outer peripheral portion of the rectilinear guide tube 63, and the rectilinear groove is formed in the inner peripheral portion of the first group barrel 11. Engagement of the provided projections restricts the movement of the first group barrel 11 in the rotational direction.

A part of the second group lens barrel 21 is disposed on the inner peripheral side of the rectilinear guide tube 63, and the second lens group 20 is moved by the cam mechanism in the same manner as the first lens group 10. That is, a cam pin (not shown) provided in the second group barrel 21 is cam-engaged with the second group cam groove of the cam barrel 61. The straight guide tube 63 is provided with a through groove (not shown) along the direction of the first optical axis A, and this through groove is an engagement disposed at the root of the cam pin of the second group barrel 21. The parts engage. As a result, the movement of the second group barrel 21 in the rotational direction is restricted.
When the cam barrel 61 is rotated by a motor and a transmission mechanism (not shown), the convex portion provided in the first group barrel 11 with the first group cam groove of the cam barrel 61 and the cam pin of the first group barrel 11 cam-engaged. Slides along the direction of the first optical axis A in the rectilinear groove of the rectilinear guide tube 63. The first group barrel 11 advances and retreats along the optical axis with respect to the cam barrel 61. When the cam cylinder 61 advances and retreats along the direction of the first optical axis A with respect to the fixed cylinder 62, the first group lens barrel 11 advances and retracts along the first optical axis A with respect to the cam cylinder 61. The lens 1 moves between the storage position and the photographing position. The second group lens 2 also moves between the storage position and the photographing position by the same cam action and operation.

  Next, the optical adjustment of the adjustment lens 7 will be described with reference to FIGS. FIG. 5 is a perspective view of the main part showing the holding member 6 and the adjustment lens 7. The holding member 6 is provided with a ring-shaped convex portion 6 b as a holding portion for performing rough adjustment of the adjustment lens 7 and an adhesive reservoir 6 c on the side facing the image sensor 9. In this example, the ring-shaped convex portion 6b is used to determine the rough position of the adjustment lens 7, and when the final adjustment of the adjustment lens 7 is completed, the lens is bonded and fixed. The inner diameter portion of the ring-shaped convex portion 6 b has a gap with respect to the outer diameter of the adjustment lens 7, and this gap becomes an eccentricity adjustment range of the adjustment lens 7. The operator adjusts the position of the adjustment lens 7 using a tool or the like, and then fixes the adjustment lens 7 by injecting an adhesive into the adhesive reservoir 6c. The adjusting lens 7 absorbs dimensional errors and assembly errors of the third lens group 30 and the fourth lens group 40 on the second optical axis B, and improves the optical performance of the optical member positioned on the second optical axis B. It has an adjustment function to guarantee.

FIG. 6 is a perspective view showing a main part of the lens barrel related to adjusting the adjustment lens 7. The pair of guide bars 16 supports the holding member 6, the third lens group 30, and the fourth lens group 40, and guides them while being movable along the direction of the second optical axis B. The lens barrel base 17 holds the guide bar 16, the optical filter 8, the image sensor 9, the fixed cylinder 62, and the like. As illustrated, when adjusting the adjustment lens 7, the first lens group 10, the second lens group 20, the optical filter 8, and the image sensor 9 that are held by the fixed cylinder 62 and the fixed cylinder 62 are not attached. The prism 5 is not attached to the holding member 6.
The holding member 6 is provided with an opening 6 a on the optical axis B on the side opposite to the imaging element 9. The lens barrel base 17 is provided with an opening 17 a on the optical axis B opposite to the image sensor 9. These openings 6a and 17a are formed in each part so that the light beam that has passed through the adjusting lens 7 reaches a detection unit (not shown) as will be described later, and accordingly the light beam is blocked on the second optical axis B. There is no member, and light from an external light source described later can be passed through the lens barrel. Note that the shutter drive unit 30 a fixed to the holding member 6 side by the front base plate 32 is movable along the second optical axis B.

FIG. 7 is a schematic diagram when the optical adjustment method of the adjustment lens 7 is performed. A light source 51 and an adjustment chart 52 are installed on the second optical axis B with respect to the lens barrel. The adjustment chart 52 is installed at the same position as the image sensor 9 to be attached in a later process. On the optical axis B opposite to the light source 51 and the adjustment chart 52, an adjustment tool lens 53 and an adjustment tool sensor 54 are installed. Light emitted from the light source 51 passes through the adjustment chart 52, the fourth group lens 4, the third group lens 3, and the adjustment lens 7 and passes through the opening 6 a provided in the holding member 6. Then, the light exits from the opening 17 a and passes through the adjustment tool lens 53, and a detection image of the chart drawn on the adjustment chart 52 is obtained at the light receiving portion of the adjustment tool sensor 54. The adjustment tool lens 53 and the adjustment tool sensor 54 constitute a detection optical system (detection means). When the operator displaces the position of the adjustment lens 7 in the direction of the arrow, that is, in the direction orthogonal to the second optical axis B, the blur amount and distortion of the formed chart image change. The adjustment tool sensor 54 reads the formed chart and evaluates the blur amount and distortion of the formed chart image with a processing device (not shown), so that the operator can adjust the optical adjustment state by the adjustment lens 7 based on the evaluation result. Can be judged. The opening 6a provided in the holding member 6 and the opening 17a provided in the lens barrel base 17 have a sufficient size to transmit an amount of light flux necessary for evaluation of the formed chart image.
After the adjustment of the adjustment lens 7 is completed and the lens is bonded and fixed, the operator attaches the prism 5 to the holding member 6, and the prism cover 15 blocks the opening 6 a provided in the holding member 6 to block light. Thereafter, the operator attaches the fixed barrel 62 holding the cam barrel 61, the first lens group 10, the second lens group 20 and the like to the barrel base 17, and closes the opening portion 17a of the barrel base with the fixed barrel 62. Thus, the lens barrel is completed.

  As described above, in the present embodiment, optical adjustment can be performed using only the lens group along the second optical axis B on the image sensor 9 side of the prism 5. Further, since the adjustment of the adjustment lens 7 can perform the optical adjustment excluding the component of the mounting error of the prism 5, more accurate optical adjustment is possible.

Next, a countermeasure for preventing a component that is not strong enough to withstand the interference from interference between the movable members will be described.
When the lens group that moves along the first optical axis A and the lens group that moves along the second optical axis B move individually in the lens barrel, the lens barrel moves to the storage position along the optical axis B. It is assumed that the lens group moving along the optical axis A is retracted before the moving lens group is retracted. In this case, there exists a possibility that components may contact. For example, as shown in FIG. 3, the first lens group before the prism 5, the third lens group 30, and the fourth lens group 40 move to the image sensor 9 side along the optical axis B and reach the storage position. It is assumed that the lens 10 and the second lens group 20 are retracted along the optical axis A. In this case, there is a possibility that a component having a low strength is damaged due to interference between members. In the following, countermeasures for problems caused by such interference will be described.

  FIG. 8 is an exploded perspective view of the lens barrel showing the positional relationship between the rectilinear guide tube 63, the shutter drive unit 30a, and the movement amount restricting unit 6d. In the figure, Y indicates the distance between the rectilinear guide tube 63 and the shutter drive unit 30a in the direction of the first optical axis A, and Z indicates the rectilinear guide tube 63 and the movement amount regulation in the direction of the first optical axis A. The distance with the part 6d is shown. Since the movement amount restricting portion 6d provided on the holding member 6 in the direction of the first optical axis A is located closer to the subject than the shutter driving portion 30a, the distance Z is smaller than the distance Y (Z <Y). .

Hereinafter, a case where an external force is applied to the first lens group 10 and the like when the lens barrel moves from the photographing state at the TELE position shown in FIG. 2 to the SINK position (storage position) shown in FIG. 3 will be described.
As shown in FIG. 4, a cam pin (not shown) of the cam cylinder 61 is cam-engaged with the cam groove 62 a of the fixed cylinder 62. Positions 62c to 62e represent positions where the cam pins are engaged with the cam grooves 62a. At positions 62c and 62e, the cam pin is engaged with the linear groove of the cam groove 62a, and at position 62d, the cam pin is engaged with the inclined groove of the cam groove 62a. A case is assumed in which an external force is applied to the first lens group 10 and the like in a state where the cam pin is in the inclined groove of the cam groove 62a, that is, a position having a large inclination as in the position 62d. Due to the external force, the cam cylinder 61 moves in the direction of the storage position while rotating along the inclined portion of the cam groove 62a. At this time, when the third lens group 30 is not retracted to the retracted position as shown in FIG. 8, the shutter drive unit 30a and the straight guide tube 63 may interfere with each other and the shutter drive unit 30a may be damaged.
In the present embodiment, the movement amount regulating portion 6d is provided in the holding member 6, and the relationship of “Z <Y” is established. Therefore, before the rectilinear guide tube 63 comes to a position where it interferes with the shutter drive unit 30a as shown in FIG. 8, the restricting surface of the moving amount restricting portion 6d comes into contact with a part of the rectilinear guide tube 63 and moves further ( Regulate retreat). Thereby, it is possible to protect the shutter drive unit 30a without increasing the mechanical strength.

  As described above, in this embodiment, when the movable member (including the rectilinear guide tube 63) that moves forward and backward along the first optical axis A moves to the storage position with the holding member 6 in the photographing position. The holding member 6 is provided with a movement amount regulating portion 6d for regulating the movement. As a result, before the lens group moving along the second optical axis B is retracted to the storage position, even if the movable portion (front group barrel) moving along the first optical axis A is retracted, It is possible to prevent the member moving along the optical axis B of 2 from interfering with and being damaged.

  In addition, this invention is not limited to the structure illustrated to the said embodiment, A material, a shape, a dimension, a form, a number, an arrangement | positioning location, etc. can be suitably changed in the range which does not deviate from the summary of this invention. For example, although the prism 5 is shown as the bending optical element in the above example, the present invention is not limited to this, and a mirror or the like may be used. In the above example, the adjustment lens 7 is provided on the holding member 6, but the lens for optical adjustment may be, for example, the third group lens 3 or the fourth group lens 4. In the above description, a configuration example for preventing the straight guide tube 63 and the shutter drive unit 30a from interfering with each other is shown. However, the present invention is not limited to this. For example, a means (regulator) for preventing interference between the second lens group 20 and the backplate 34 may be provided.

1, 2 lenses (first optical member)
3,4 lenses (third optical member)
5 Prism (bending optical element)
6 Holding member 6a Opening 6d Movement amount restricting portion 7 Adjustment lens (second optical member)
Reference Signs List 15 prism cover 17 lens barrel base 17a opening 30a shutter drive unit 63 rectilinear guide tube

Claims (8)

A first optical member disposed on the first optical axis;
An optically adjustable second optical member disposed on the second optical axis;
A bending optical element that changes an optical path from the first optical axis to the second optical axis;
A lens barrel including a third optical member disposed on the second optical axis,
When the second optical member is disposed on the second optical axis and optical adjustment of the optical member is performed, light from a light source used for optical adjustment is transmitted along the second optical axis. 3. A lens barrel characterized in that it passes through the optical member 3 and the second optical member, passes through the lens barrel and is emitted to the outside through the opening. A holding member for the bending optical element;
The lens barrel according to claim 1, wherein the second optical member subjected to the optical adjustment is fixed to the holding member. The holding member has an opening formed to pass light from the light source,
The lens according to claim 2, wherein a light shielding member that shields light along the second optical axis is attached to the opening of the holding member to which the second optical member is fixed. A lens barrel. A movable part that holds the first optical member and moves between a photographing position and a storage position along the first optical axis;
A holding member that holds the bending optical element and the second optical member and moves along the second optical axis;
A third optical member that moves along the second optical axis or a member that moves together with the third optical member;
When the third optical member or a member that moves together with the third optical member moves along the second optical axis, the movement of the movable portion to the storage position is restricted, thereby the third optical member. 2. The lens barrel according to claim 1, wherein the holding member is provided with restricting means for preventing interference between the optical member or a member that moves together with the third optical member and the movable portion. The holding member moves along the second optical axis perpendicular to the first optical axis;
The distance between the restricting means and the movable portion in the direction of the first optical axis is the third optical member in the direction of the first optical axis or a member that moves together with the third optical member and the movable The lens barrel according to claim 4, wherein the lens barrel is smaller than a distance to the portion. The lens barrel according to any one of claims 1 to 5,
An imaging apparatus comprising: an imaging element disposed on the second optical axis.   The holding member of the bending optical element has a holding part for holding the second optical member in order to perform rough adjustment of the second optical member on the imaging element side. The imaging device described. A first optical member disposed on the first optical axis; an optically adjustable second optical member disposed on the second optical axis; and the second light from the first optical axis. Optical adjustment method for optically adjusting the second optical member with a lens barrel including a bending optical element that changes the optical path to the axis and a third optical member disposed on the second optical axis Because
In a state where the second optical member is arranged on the second optical axis, a light source and an adjustment chart used for optical adjustment of the second optical member are arranged, and from the light source via the adjustment chart A step of disposing detection means for detecting light that passes through the third optical member and the second optical member along the second optical axis, passes through the lens barrel, and is emitted to the outside from the opening; When,
And a step of adjusting the position of the second optical member in a direction orthogonal to the second optical axis based on a detection image of the adjustment chart formed on the detection means. Method.

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