JP2005062342A - Lens-barrel driving mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens-barrel driving mechanism which is easily miniaturized. <P>SOLUTION: A second lens frame 3 is provided with a shutter unit 8 movable in an optical axis direction. A first lens frame 2 presses the shutter unit 8 along with a letting-in operation, as a result, the shutter unit 8 moves to a rear side with respect to the second lens frame 3 and a second lens group 31 is arranged into exposure apertures 81a and 82a with opened shutter blades 83. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lens barrel drive mechanism, and more particularly to a lens barrel drive mechanism used in an optical system apparatus.

2. Description of the Related Art Conventionally, there is known a lens barrel driving mechanism used for zooming and focus adjustment while driving two front and rear lens groups in the front-rear direction (see, for example, Patent Document 1).
For example, as shown in FIG. 4, the lens barrel driving mechanism 100 includes a lens barrel cover 101, a cam barrel 102, a fixed barrel 103, a first lens frame 104, a second lens frame 105, and a third lens frame 106. These members 101 to 106 have a substantially cylindrical shape, and are superposed so that optical axes passing through substantially the centers of the openings of the members 101 to 106 substantially coincide with each other. The first lens frame 104, the second lens frame 105, and the third lens frame 106 hold the first lens group 104a, the second lens group 105a, and the third lens group 106a, respectively. The second lens frame 105 is configured to be movable in the optical axis direction by a cam structure including a cam cylinder 102 and a fixed cylinder 103.
Also, a shutter unit 107 having a shutter blade 107c that opens and closes or opens an exposure opening 107b formed in the shutter substrate 107a is housed between the first lens group 104a and the second lens group 105a. Yes. The shutter unit 107 is fixedly attached to the second lens frame 105 in front of the second lens frame 105, and the shutter unit 107 is integrated with the movement of the second lens frame 105 in the optical axis direction. To move.
JP 2002-333666 A

  However, as described above, the shutter unit 107 is fixedly attached to the second lens frame 105 and does not hit the shutter blade 107c so as not to disturb the opening / closing operation of the shutter blade 107c, that is, the shutter blade 107c. The second lens group 105a is disposed at a predetermined distance from the second lens group 105a. As a result, in the retracted state, the total length in the optical axis direction becomes longer due to the thickness of the shutter unit 107 and the thickness of the second lens group 105 and the distance between the shutter blade 107c and the second lens group 105a. It cannot be stored compactly. In addition, it is difficult to reduce the size of an optical apparatus such as a camera provided with the lens barrel driving mechanism 100 as a constituent member.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lens barrel drive mechanism that can be easily downsized.

In order to solve the above problems, the invention of claim 1 includes, for example, a first lens group 21 disposed in front as shown in FIG.
A second lens group 31 disposed rearward;
A shutter unit 8 that is disposed between the first lens group and the second lens group and has a shutter blade 83 that opens and closes or narrows the exposure openings 81a and 82a;
A first lens frame 2 holding the first lens group;
A second lens frame 3 holding the second lens group;
Driving means for extending and retracting the first lens frame and the second lens frame in the optical axis direction (for example, the first frame portion 22, the second frame portion 34a, the fixed cylinder 5, the slit 51, and the straight groove) 52, a cam barrel 6, a first cam groove 61, and a second cam groove 62).
The shutter unit is provided on the second lens frame so as to be movable in the optical axis direction.
The exposure in which the shutter unit is moved rearward with respect to the second lens frame and the shutter blades are opened as the first lens frame presses the shutter unit along with the retraction operation. The second lens group is disposed in the opening.

According to the first aspect of the present invention, the first lens frame presses the shutter unit along with the retraction operation, so that the shutter unit moves rearward with respect to the second lens frame, and within the exposure opening. Since the second lens group is arranged, as compared with the conventional case where the shutter unit is fixedly attached to the second lens frame at a predetermined interval so that the second lens group does not hit the shutter blade. The entire thickness of the shutter unit, the second lens group, and the second lens frame can be reduced by the amount that the second lens group is housed in the exposure opening, and the lens barrel driving mechanism is reduced accordingly. be able to.
In addition, since the second lens group is accommodated by using the space in the exposure opening of the shutter unit in this way, it is possible to reduce the size with an easy structure, and a camera equipped with such a lens barrel drive mechanism. The size can be reduced.

The invention of claim 2 is a lens barrel drive mechanism according to claim 1, for example, as shown in FIG.
The second lens frame is engaged with the shutter unit and guides the shutter unit so as to be movable in the optical axis direction. The second lens frame is provided at a front end portion of the guide unit to restrict movement of the shutter unit. And a key portion 33a
An elastic member (for example, a spring 32a) is provided between the second lens frame and the shutter unit,
During the retraction operation, the first lens frame presses the shutter unit rearward against the urging force of the elastic member,
During the extending operation, the first lens frame moves to the front side, and the shutter unit moves to the front side along the guide portion by the urging force of the elastic member, and the movement is stopped at the key portion. And

  According to the invention of claim 2, during the retraction operation, the first lens frame presses the shutter unit rearward against the urging force of the elastic member, so that the second lens group is placed in the exposure opening of the shutter unit. Be placed. On the other hand, at the time of the extending operation, the first lens frame moves to the front side, the shutter unit moves to the front side along the guide portion by the biasing force of the elastic member, and the movement is stopped at the key portion. As described above, since the position of the shutter unit is automatically regulated in accordance with each of the feeding operation and the feeding operation, it is not necessary to provide a drive mechanism for driving the shutter unit. Also, the lens barrel drive mechanism can be downsized. In addition, each of the second lens frame and the shutter unit can have a simple structure, and its manufacture is easy and the cost can be reduced.

  According to the lens barrel driving mechanism according to the present invention, the second lens group is disposed in the exposure opening along with the retraction operation, so that the shutter unit, as much as the second lens group is accommodated in the exposure opening. The entire thickness of the second lens group and the second lens frame can be reduced, and the size can be reduced with an easy structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, a case where the lens barrel driving mechanism is applied to a digital camera exemplified as an example of an optical device will be described.
FIG. 1 is a sectional view taken along the optical axis of the lens barrel driving mechanism according to the present embodiment and shows a case where the lens barrel is in a retracted state, and FIG. 2 is a sectional view showing the case where the lens barrel driving mechanism is in a wide state. FIG. 3 is a cross-sectional view of the same and is an explanatory view showing a case in a tele state.
In the following description, the state in which the digital camera can capture the widest range of subjects is referred to as the wide state (the state in which the image can be captured in the widest range), and the state in which the subject can be captured at the highest magnification in the narrowest range. Is referred to as a tele state (a state in which imaging can be performed in the narrowest range), and a state in which each member is housed and made most compact when the digital camera is not used is referred to as a retracted state.

First, the configuration of the lens barrel drive mechanism will be described with reference to FIG.
The lens barrel drive mechanism 1 mainly includes a first lens frame 2, a second lens frame 3, a third lens frame 4, a fixed barrel 5, a cam barrel 6, and a barrel cover 7. These members 2 to 7 are held in a state where the optical axes passing through the approximate centers of the members 2 to 7 substantially coincide.

The first lens frame 2 is formed in a substantially cylindrical shape with an open rear end, and holds the first lens group 21 at its front end. On the side wall portion at the rear end portion of the first lens frame 2, a first frame portion 22 penetrating the side wall portion is provided. The first top portion 22 includes an inward protruding portion 22 a that protrudes inward from the inner peripheral surface of the first lens frame 21, and an outward protruding portion 22 b that protrudes outward from the outer peripheral surface of the first lens frame 21. I have.
Further, the front end portion of the first lens frame 2 that holds the first lens group 21 is brought into contact with the front surface of the shutter unit 8 disposed behind the first lens group 21 in accordance with the retraction operation. An abutting portion 23 is provided for pressing and moving the unit 8 to the rear side.

Here, the shutter unit 8 is provided between the shutter substrate 81 and the cover plate 82, and the shutter substrate 81 and the cover plate 82, which are provided so as to be movable in the optical axis direction and in which the exposure openings 81a and 82a are formed. A shutter blade 83 that opens and closes the exposure openings 81a and 82a, and a driving source 84 that is provided on the cover plate 82 and drives the shutter blade 83. These members 81 to 84 are arranged in the order of the shutter substrate 81, the shutter blade 83, the cover plate 82, and the drive source 84 from the front side.
Cutout portions (not shown) that engage with guide portions 33 of the second lens frame 3 to be described later are formed on the outer peripheral edge portions of the shutter substrate 81 and the cover plate 82.
The drive source 84 opens and closes the exposure openings 81a and 82a or narrows down to a predetermined aperture by driving the shutter blade 83 based on a command from a control circuit (not shown) provided inside the camera.

Further, a caliper ring 24 and a barrier mechanism 25 are attached to the front end portion of the first lens frame 2 where the first lens group 21 is provided.
The barrier mechanism 25 includes a barrier drive ring 25a and barrier blades 25b that are opened and closed by the barrier drive ring 25a.

The fixed cylinder 5 is provided inside the first lens frame 2 and holds the first lens frame 2 and the second lens frame 3 movably along the optical axis direction. A slit 51 is formed in the side wall of the fixed cylinder 5 along the optical axis direction so as to penetrate the side wall.
Further, a rectilinear groove 52 that engages with an inward projecting portion 22a of the first frame portion 22 provided in the first lens frame 2 is formed on the outer surface of the fixed cylinder 5 along the optical axis direction. . The rectilinear groove 52 is guided in the optical axis direction in a state where the inward protruding portion 22a is restricted from moving in the circumferential direction, and therefore the width thereof is set slightly larger than the outer diameter of the inward protruding portion 22a. Has been.
Further, the rear end portion of the fixed cylinder 5 has an extending portion 53 protruding outward.

  The second lens frame 3 is provided inside the fixed cylinder 5 and holds the second lens group 31 behind the shutter unit 8. The second lens frame 3 is in contact with the periphery of the second lens group 31 to hold the second lens frame 3 and extends forward from the front end of the holding part 32. A guide portion 33 that guides the shutter unit 8 so as to be movable along the optical axis direction, and a mounting portion 34 that extends outward from the rear end portion of the holding portion 32 and is attached to the fixed cylinder 5 are provided. Yes.

Coil springs 32a are attached to the outside of the holding portion 32 and between the holding portion 32 and the rear surface of the shutter unit 8, respectively. In addition to the coil spring 32a, an elastic member such as rubber can be used.
The guide part 33 is engaged with a notch part formed in the shutter substrate 81 and the cover plate 82 constituting the shutter unit 8, and moves the shutter unit 8 in the optical axis direction along the extending direction of the guide part 33. It is possible. Further, at the front end portion of the guide portion 33, a convex key portion 33a for restricting the movement of the shutter unit 8 when the shutter unit 8 moves forward along the guide portion 33 is provided. . That is, the shutter unit 8 is prevented from jumping forward by the key portion 33a, and the key portion 33a acts as a stopper.

Three mounting portions 34 are provided at intervals of 120 degrees on the same circumference centered on the center line of the holding portion 32 (not shown).
The mounting portion 34 is formed so as to penetrate the slit 51 formed in the fixed cylinder 5 from the inside, and a second frame portion 34a protruding outward is formed at the rear end portion of the mounting portion 34. Is provided. Here, since the outer diameter of the second piece 34a is set slightly smaller than the width of the slit 51, the second piece 34a is guided by the slit 51 in the optical axis direction. The movement is restricted in the circumferential direction.

  The third lens frame 4 is provided inside the fixed barrel 5 and holds the third lens group 41 behind the second lens group 31. A motor 42 for adjusting the position of the third lens group 41 by moving the second lens frame 3 in the optical axis direction is connected to the outer periphery of the third lens frame 4. That is, the motor 42 is fixed to the inside of the fixed cylinder 5, and the third lens frame 4 is screwed into a screw provided on the output shaft of the motor 42. As the motor 42 rotates, the distance between the third lens group 41 and the imaging unit 9 disposed behind the third lens group 41 is adjusted so that the focus is achieved.

  Here, the imaging unit 9 includes a receiving portion 91 attached to the rear end portion of the inner periphery, a low-pass filter 92 fitted in the receiving portion 91, and a light receiving element provided at the rear portion of the low-pass filter 92 via an elastic body 93. 94 and a pressing plate 95 that sandwiches the light receiving element 94 with the low-pass filter 92.

The cam cylinder 6 is provided outside the first lens frame 2 and holds the first lens frame 2 and the second lens frame 3 movably along the optical axis direction. A first cam groove 61 is formed in the front portion of the inner peripheral surface of the cam cylinder 6 to engage with the outward projecting portion 22b of the first frame portion 22 provided in the first lens frame 2. A second cam groove 62 is formed in the rear portion of the inner peripheral surface of the cylinder 6 so as to engage with the second frame portion 34 a provided in the second lens frame 3. Further, the first cam groove 61 is formed deeper than the second cam groove 62 in order to easily withstand an impact when the camera is dropped.
Further, near the rear end portion of the outer peripheral surface of the cam barrel 6, there is provided a gear portion 63 through which power is transmitted by meshing with a drive gear (not shown) of a camera to which the lens barrel drive mechanism 1 is attached.

  The lens barrel cover 7 is provided outside the cam barrel 6, and its rear end surface is in contact with and fixed to the extension portion 53 of the fixed barrel 5. The front end portion of the lens barrel cover 7 is formed so as to project inward, and abuts against the front end portion of the cam barrel 6 to prevent the cam barrel 6 from moving in the forward direction.

Next, the operation of the lens barrel drive mechanism 1 will be described.
As shown in FIG. 1, when a driving force from a motor (not shown) is transmitted to the gear portion 63 of the cam barrel 6 to the lens barrel drive mechanism 1 in the retracted state, the cam barrel 6 rotates. Along with the rotation of the cam cylinder 6, the outward projecting portion 22 b of the first frame portion 22 provided in the first lens frame 2 moves straight forward along the first cam groove 61. At the same time, the second frame portion 34 a of the second lens frame 3 also moves straight forward along the second cam groove 62. At this time, the inward projecting portion 22 a of the first piece portion 22 is restricted from moving in the circumferential direction by the rectilinear groove 52 of the fixed tube 5, and the second piece portion 34 a is restricted by the slit 51 of the fixed tube 5. Since the movement in the circumferential direction is restricted, both move in the optical axis direction without rotating in synchronization with the cam cylinder 6.

  On the other hand, in the retracted state, the shutter unit 8 stopped when the contact portion 23 of the first lens frame 2 pushes the front surface of the shutter unit 8 rearward against the biasing force of the spring 32a is When the lens frame 2 moves straight forward, it is moved forward along the guide portion 33 of the second lens frame 3 by the biasing force of the spring 32a, and is stopped by being locked by the key portion 33a.

Thereafter, when the cam cylinder 6 rotates by a predetermined distance, the first lens group 21 is extended and the wide state shown in FIG. 2 is obtained. The first lens frame 21 is in the widened state and is in the most extended state. When the cam cylinder 6 is further rotated, the first lens frame 21 is retracted until the telescopic state shown in FIG. At this time, the second lens frame 3 is extended forward by the guide of the second cam groove 62 engaged with the second frame portion 34a, and zooming is performed by changing the group interval.
Further, the motor 42 adjusts the position of the second lens frame 3 and moves the third lens group 41 according to the positions of the first lens group 21 and the second lens group 31, so that the focus is on the imaging unit 9. Will fit.

  In the operation of returning from the tele state to the wide state and further storing the lens groups 21, 31, and 41, the cam cylinder 6 rotates in the direction opposite to that when it is extended. By this rotation, the first lens frame 2 in the wide state is retracted by the guide of the first cam groove 61, and the first lens frame 2 and the second lens frame 3 are retracted to the retracted state.

  At this time, the contact portion 23 of the first lens frame 2 contacts the front surface of the shutter unit 8 and stops. That is, as the first lens frame 2 is retracted, the contact portion 23 of the first lens frame 2 presses the front surface of the shutter unit 8 to the rear side. The shutter unit 8 stopped at the front end portion of the guide portion 33 by 33a moves rearward along the guide portion 33 against the urging force of the spring 32a, and the exposure opening portion in which the shutter blade 83 is opened. A part of the second lens group 31 is disposed and accommodated in 81a and 82a. Note that the shutter blade 83 is held in a state in which the exposure openings 81 a and 82 a are opened by the drive source 84. Thereafter, the barrier blade 25b is closed at a predetermined position.

  As described above, according to the lens barrel drive mechanism 1 of the embodiment of the present invention, during the retraction operation, the first lens frame 2 presses the shutter unit 8 rearward against the urging force of the spring 32a. The second lens group 31 is disposed in the exposure openings 81a and 82a. On the other hand, during the extension operation, the first lens frame 2 moves to the front side, the shutter unit 8 moves to the front side along the guide portion 33 by the urging force of the spring 32a, and the movement is stopped at the key portion 33a. Accordingly, since the second lens group 31 is disposed in the exposure openings 81a and 82a in accordance with the retraction operation, the shutter unit 8 corresponds to the amount that the second lens group 31 is accommodated in the exposure openings 81a and 82a. The entire thickness of the second lens group 31 and the second lens frame 3 can be reduced, and the lens barrel drive mechanism 1 can be easily downsized. Further, it is possible to reduce the size of the camera provided with such a lens barrel drive mechanism 1.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change suitably.
For example, the shutter unit 8 and the second lens frame 3 are configured such that the guide unit 33 of the second lens frame 3 is engaged with a notch formed in the shutter substrate 81 and the cover plate 82 of the shutter unit 8, thereby 8 is configured to be movable with respect to the second lens frame 3. However, the present invention is not limited to this, and, for example, guides that protrude from the outer peripheral edge of the shutter substrate 81 and the cover plate 82 are provided. It is good also as a structure which provided the part (not shown) and formed the groove part (not shown) for engaging a guide part with the guide part 33 along the extension direction of the guide part 33, and the shutter unit 8 is the 2nd lens. Any structure that can move in the optical axis direction with respect to the frame 3 may be used.

  In the above embodiment, the method of driving each member with the cam structure has been described. However, the present invention is not limited to the above-described method, and may be a method of driving with a helicoid structure.

  Furthermore, in the above embodiment, the three lens groups of the first lens group 21, the second lens group 31, and the third lens group 41 are provided, but a configuration including two lens groups may be used. A configuration including four or more lens groups may be used.

FIG. 5 is a cross-sectional view taken along the optical axis in the retracted state of the lens barrel drive mechanism for illustrating an embodiment of the present invention. It is sectional drawing along the optical axis in the wide state of a lens-barrel drive mechanism similarly. It is sectional drawing along the optical axis in the tele state of a lens-barrel drive mechanism similarly. FIG. 10 is a cross-sectional view taken along the optical axis in the condensing state of the lens barrel drive mechanism for showing a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens barrel drive mechanism 2 1st lens frame 3 2nd lens frame 5 Fixed cylinder (drive means)
6 Cam cylinder (drive means)
8 Shutter unit 21 First lens group 22 First frame section (drive means)
31 Second lens group 32a Spring (elastic member)
33 Guide part 33a Gear part 34a Second top part (drive means)
51 Slit (drive means)
52 Straight groove (drive means)
61 First cam groove (drive means)
62 Second cam groove (drive means)
81a, 82a Exposure opening 83 Shutter blade

Claims (2)

A first lens group disposed in front;
A second lens group disposed rearward;
A shutter unit that is disposed between the first lens group and the second lens group and includes shutter blades that open and close or narrow an exposure opening;
A first lens frame for holding the first lens group;
A second lens frame for holding the second lens group;
A lens barrel drive mechanism comprising drive means for extending and retracting the first lens frame and the second lens frame in the optical axis direction;
The shutter unit is provided on the second lens frame so as to be movable in the optical axis direction.
As the first lens frame presses the shutter unit along with the retraction operation, the front shutter unit moves rearward with respect to the second lens frame, and the shutter blades are opened. The lens barrel drive mechanism, wherein the second lens group is disposed in the opening. The second lens frame engages with the shutter unit and guides the shutter unit so as to be movable in the optical axis direction. The second lens frame is provided at a front end of the guide unit to restrict the movement of the shutter unit. With a key part,
An elastic member is provided between the second lens frame and the shutter unit,
During the retraction operation, the first lens frame presses the shutter unit rearward against the urging force of the elastic member,
During the extending operation, the first lens frame moves to the front side, and the shutter unit moves to the front side along the guide portion by the urging force of the elastic member, and the movement is stopped at the key portion. The lens barrel drive mechanism according to claim 1.

Images