JPH03156411A - Lens barrel - Google Patents

Abstract

PURPOSE:To compact a lens barrel using a worm gear by arranging two motors so that their output axes are approximately rectangular to the optical axis direction. CONSTITUTION:In the lens barrel having two motors for focusing and zooming, the two motors 11, 17 are arranged between a stop unit 4 having a spatial margin in the diameter direction and an optical focusing face 2a so that the output axes of the motors 11, 17 are approximately rectangular to the optical axis. Since the output axes of the motors 11, 17 are approximately diameter direction (approximately rectangular to the optical axis), a reduction mechanism using a low noise worm can be used. Consequently, a large reduction ratio can easily obtained by the small number of parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens barrel used in a video camera or the like, and more particularly to a lens barrel having at least focusing and zooming motors.

[Prior Art] Conventionally, the actuator (motor) for driving the focus and zoom of a small video lens barrel has been operated at a position where the lens diameter is small due to optical design, specifically at the aperture position and the optical focus position (sensor). position), and the outer diameter of the entire lens was made as small as possible. In this case, the motor as the actuator for driving the lens is
- In terms of the shell, the output shaft of the small DC motor was arranged parallel to the optical axis. At that time, a speed reduction mechanism including a plurality of spur gears was formed between the output shaft of the motor and the driven object, such as a focus lens holding cylinder or a zoom lens holding cylinder.

On the other hand, the aperture unit used in lens barrels for small video cameras has a thin rectangular parallelepiped aperture mechanism with as few blades as possible (-2 blades) and a drive unit that uses a braking coil. It is common to have a diaphragm unit with a diaphragm attached to it.

In terms of optical design, this diaphragm unit is generally placed near the center of the lens unit. To explain the overall layout of the lens barrel, the diaphragm unit is placed near the center of the unit, and the lens drive motor has its output shaft located at a small part of the lens outline between the diaphragm unit and the optical focus surface. placed parallel to the optical axis. On the other hand, the focus lens holding cylinder and the zoom lens holding cylinder, which are driven objects, are arranged toward the tip of the lens (in front of the optical axis) with the diaphragm unit as a boundary. Therefore, in general, the deceleration mechanism that decelerates the output of the lens drive motor passes near the outer periphery of the diaphragm unit and extends toward the lens tip, and is connected to a large gear on the outer periphery or inner periphery of the lens holding cylinder or transmission cylinder. is engaged with. This rotational force causes the lens to move in the optical axis direction using a well-known helicoid mechanism or cam mechanism to perform focusing or zooming.

[Problems to be solved by the invention] However, in the conventional example described above, the deceleration mechanism is complicated and there are restrictions on the location of the deceleration mechanism, and the motor itself is quite large, so it is difficult to create a compact and inexpensive lens barrel. That was difficult. In addition, there is a strong desire to make video cameras more compact, and it is naturally desirable to make lens barrels more compact.

[Means for Solving the Problems] The present invention provides a lens barrel having two motors for focusing and zooming, by arranging both motors so that their output axes are substantially orthogonal to the optical axis direction. To provide a lens barrel that reduces restrictions on the length of the entire lens barrel due to the length of a motor and allows the use of a worm gear obtained by a gear with a small number of large reduction ratios in a reduction system.

[Example] A detailed explanation will be given below according to the drawings.

FIG. 1 is a view of the lens barrel according to this embodiment, viewed from a direction perpendicular to the optical axis, and numeral 1 denotes an imaging unit including an imaging element 2a and a processing circuit 2b. Note that the position of the image sensor 2a is the optical focus plane position.

3 is a lens barrel body that holds an aperture unit 4 and also has the image pickup unit 1 fixed thereon. 4a is an aperture drive actuator section, a meter, and a motor, and 4b is an aperture mechanism section (a moving section for aperture blades). In addition, the lens barrel body 3 includes a focus drive amount large gear 5 and a zoom drive gear 6.
However, it is installed so that it can rotate freely. Each large gear 5.6 moves the focus lens 3a and zoom lens 3b in the optical axis direction using a well-known helicoid mechanism or cam mechanism.

Reference numeral 9a denotes a focus drive small gear, which meshes with the focus drive amount large gear 5. Reference numeral 8 designates a bearing for transmission @9 which is integrally constructed with the small gear 9a. A worm wheel 10 is coaxially and integrally fixed to the transmission shaft 9. The worm wheel 10 meshes with a worm lla fixed to the output shaft of the motor 11 (in a direction perpendicular to the optical axis). 12 is a gear box, ohm gear 1
0.11a and the motor 11 are fixed as a unit and can be easily handled as parts. In particular, this gear box 12 is made of a resin material containing an electromagnetic wave absorbing material to prevent electrical noise from being emitted to the outside. Similarly, to describe the configuration for the zoom drive, 13 is a zoom drive small gear, 14 is a bearing of the shaft 15, 15 is a shaft integrally constructed with the small gear 13, 16 is a worm wheel,
is integrally fixed to. 17 is a motor with a worm 17a fixed to the output shaft, 18 is a gear box, and the motor 17 and the worm gears 16, 1? a is unitized. Further, the gear boxes 12 and 18 are integrally constructed by a member 19. In addition, the above-mentioned large gear 5.
6 is shifted in the optical axis direction, the small gear 9
Since a and 13 are also shifted in the optical axis direction, there is no need to increase the diameter of the lens barrel.

2 is a right side view of the lens barrel shown in FIG. 1. FIG. However, the imaging unit 1 is omitted.

20 is a case lid, and a hook part 2 is attached to the gear box 12.
It is fitted at 0a and 20b. At this time, the elastic part 2
The structure is such that the motor 11 is held down at 0c and the transmission shaft 9 is also held down at the same time by the holding part 20d. A gear box 12.18 integrally constituted by the member 19 is attached to the lens barrel body 3 by a well-known method (snap fit, screw, etc.).
It is fixedly attached to the body via an elastic member.

FIGS. 3 and 4 show a second embodiment in which the layout of the two motors 11 and 17 explained in FIGS. 1 and 2 is changed. That is, the directions of the output shafts of the two motors are parallel to each other in the embodiment shown in FIGS. 1 and 2, but in the second embodiment shown in FIGS. directions are intersecting.

In this second embodiment, the protrusion of the two motors 11 and 17 is reduced, and the motors 11 and 17 are arranged substantially along the optical axis, thereby making the lens barrel 3 itself more flexible. It has the effect of being able to be formed into a nearly cylindrical shape. In the case of video lenses, the lens barrel is usually fixed to the main body, so the outer shape of the lens barrel itself is not much of an issue, but for lens barrels used in interchangeable lens systems, it is easier to operate if the outer shape is close to a cylindrical shape. This is important in terms of

Note that in both the first and second embodiments described above, the motor 11.1
7 is arranged so as to overlap with the actuator section 4a of the aperture unit 4 in the optical axis direction. This is effective in downsizing the entire lens barrel. This is because the actuator section 4a protrudes in the radial direction, and by overlapping the space occupied by the motors 11 and 17 (in the optical axis direction) with this protrusion, the independent protrusion due to the arrangement of the motors 11 and 17 itself is eliminated. did. In a case like this example in which the motor 11, 17 is arranged so that its output axis is approximately perpendicular to the optical axis, the radial protrusion caused by this motor is particularly a concern. The problem is addressed by doing so.

FIGS. 5 and 6 show a third embodiment, and this third embodiment shows a layout in which the aperture unit 25 is shaped like a daruma (figure 8). The aperture unit 25 in this third embodiment is an iris-type aperture mechanism consisting of three or more aperture blades, and includes an aperture drive actuator section (meter, motor) 25a and an aperture mechanism section (movement of the aperture blades). part) 25b. In addition,
The motors 11 and 17 in the third embodiment are the aperture mechanism section 25
b in the optical axis direction.

FIG. 7 is a detailed perspective view showing only the speed reduction mechanism using the war mugger in the above-mentioned embodiment. The transmission shaft 9 has end portions 9b and 9h rotatably supported by a bearing hole 8a provided in a bearing 8 configured in the lens barrel body 3 and a bearing hole 12a provided in the gear box 12, respectively. There is.

The transmission shaft 9 is made of a resin material, includes a small gear 9a that meshes with the driven gear 5, a spring presser portion 9d, and a rotation stopper portion 25a5 of the slide ring 25.
The cup 8 portion 9e, the gear removal retaining ring 26, and the bayonet-fitting claw 9g are integrally formed. A spring 23 presses the sliding ring 25 against the end surface 10b of the ohm wheel IO. The ohm Ila fixed to the output shaft of the motor 11 is aligned with the worm wheel 1o. Although the focus drive system has been described here, the zoom system has a similar configuration and will therefore be omitted.

Next, the operation will be explained.

The worm lla is rotated by energizing the motor 11 based on a signal related to focus. The ohm wheel 10 meshing with the worm lla has a spring 23
The sliding ring 25 is rotated by frictional force. The sliding ring 25 has a rotation stopper part 25a, and this part matches the D-cut part 9e of the shaft 9, so that rotational force is transmitted to the transmission shaft 9. This sliding mechanism is a transmission force absorption mechanism during manual operation. The rotational force of the transmission shaft 9 is transmitted to the small gear 9a, which rotates the large gear 5 for driving the focus lens to move the focus lens 3a in the optical axis direction to perform focus adjustment. A zooming operation is also performed in a similar manner, but the explanation of the operation will be omitted here.

In addition, by arranging the motor as in this example,
Since the layout places the electrical terminal portion of the motor away from the imaging unit 1, it also has the effect of reducing electrical noise applied to the circuit 2b within the imaging unit.

[Effects of the Invention] The present invention provides a lens barrel having two motors for focusing and zooming, in which the output shafts of the two motors are placed between the aperture unit and the optical focusing surface, which have sufficient space in the radial direction. Since the lens barrel is disposed substantially perpendicular to the optical axis, the lens barrel can be made smaller. Also, approximately radial direction of the motor output shaft (direction approximately perpendicular to the optical axis)
Therefore, a reduction mechanism using a worm can be used for low noise, and a large reduction ratio can be easily obtained with a small number of parts.

Furthermore, in the present invention, when using an aperture unit in which the drive section is arranged with a shift in the radial direction, the above two motors are arranged so as to overlap with the drive section in the optical axis direction, so that the diaphragm unit is arranged so that the drive section is shifted in the radial direction. It is possible to provide a lens barrel with reduced protrusion.

In addition, in the embodiment, the motor I that generates electrical noise
Since + and +7 are surrounded by a gear box 12.18 made of resin mixed with an electromagnetic wave absorbing material, the negative influence of noise on the image pickup element 2a and the processing circuit 2b can be reduced.

In addition, in the embodiment, the aperture unit 4 including the drive unit and the motor 1
Since 1 and 17 are gathered in one place, there is no need to lengthen the wiring for electrical mounting.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a video lens barrel as a first embodiment, Fig. 2 is a right side view of Fig. 1, and Fig. 3 is a plan view of a video lens barrel as a second embodiment. 4 is a right side view of FIG. 3, and FIG. 5 is a plan view of a video lens barrel as a third embodiment. FIG. 6 is a right side view of FIG. 5, and FIG. 7 is an exploded perspective view of the lens drive reduction mechanism. 3 is the lens barrel body 4. 25 is the aperture unit 9. 15 is the transmission shaft 11a, 17a is a ohm 0 16 is a ohm wheel 11. 17 is a motor

Claims (5)

[Claims] (1) In a lens barrel having two motors for focusing and zooming, the output axes of the two motors are substantially perpendicular to the optical axis, and the two motors are arranged between the aperture unit and the optical focusing surface. A lens barrel characterized in that a transmission shaft for transmitting the rotation of the output shafts of the two motors to a lens holding barrel for focusing and zooming is arranged parallel to an optical axis. (2) In a lens barrel having two motors for focusing and zooming, and an aperture unit in which the driving parts are arranged offset in the radial direction, the output axes of the two motors are substantially orthogonal to the optical axis, and , disposed between an aperture unit and an optical focus surface, and further disposed so that the two motors overlap with the drive section in the aperture unit in the optical axis direction, and the outputs of the two motors A lens barrel characterized in that a transmission shaft for transmitting rotation of the shaft to a lens holding barrel for focusing and zooming is arranged parallel to an optical axis. (3) The lens barrel according to claim (1) or (2), wherein the output shaft and the transmission shaft are connected by a gear mechanism including a worm. (4) The motor and the worm are unitized by a holding member, and one end of the transmission shaft is rotatably supported by the holding member.
3) The lens barrel described. (5) Driving gears for driving the corresponding lens holding cylinders are fixed to each of the two transmission shafts, and these two driving gears are arranged at shifted positions in the optical axis direction. The lens barrel according to claim (1), (2), (3) or (4).