JPH03240009A - Lens driving device - Google Patents

Abstract

PURPOSE:To prevent dust from infiltrating a lens barrel by providing a rib which is formed along the peripheral part of a slit groove provided below the external frame of a main body and providing a variable magnification sensor which is fixed in contact with the rib end surface to cover the slit groove. CONSTITUTION:A gear 36 engaged with one screw shaft 34 engaging a gear 36 rotates by the revolution of a motor 19 and a mobile frame 37 for a zoom lens moved in the direction of the optical axis 37. Simultaneously, a slid part 48 engaged with the engagement part 38 of the mobile frame 37 moves in the optical axis direction along the groove (not shown in figure) provided on the metallic plate 49 of the variable magnification sensor 30, which detects the position of the mobile frame 37 for the zoom lens. At this time, the mobile frame 37 engaged with the sliding part 48 moves in the direction of the optical axis 17 along the slit groove 45 provided on the lower center part of the external frame of the main body 1 and the variable magnification sensor 30 fixed on the surface of the rib 47 extending downward from the main body 1 through the metallic plate 49 covers the slit groove 45, so the inside of the lens barrel and outside air are shielded from each other to prevent dust from infiltrating the lens barrel and eliminate the clouding of a lens due to abrupt environmental temperature variation, thereby enabling stable photographying.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens driving device used for a photographing lens of a video camera.

Conventional technology In recent years, the development of compact video cameras that are convenient to take outdoors has been active, but in order to make video cameras smaller, it is necessary not only to make the shooting lens smaller, but also to make the lens that drives the lens smaller. The drive device also needs to be made smaller.

A conventional lens driving device will be described below with reference to the drawings.

FIG. 4 is a sectional view of SS' in FIG. 3; In Fig. 3, the outer frame of the lens barrel is the main body 1.3 group frame 8. It is composed of a master flange 21. In Figure 3, 1 is the main body,
Lenses 2, 3.4 constituting the objective lens group 5 are fixed at predetermined positions. 6 is the Nupaca between lenses 3 and 4, 7
is the lens retainer nut. 8 is 3 connected to main body 1
A lens 9 is fixed by the group frame. Reference numeral 1o denotes a guide pole provided such that both ends fit into the master flange 21 and the third group frame 8, respectively, and the zoom lens movable frame 11 holds the lenses 12, 13, and 14 constituting the variable magnification lens group 15. can slide on this guide pole.

Figure 3 shows A of the zoom lens moving frame 11 in Figure 4.
It is a cross-sectional enlarged view taken along the direction arrow. Moving frame 11 for zoom lens
As shown in FIG. 2, a U-groove is provided at the center of the upper end of the lens, and by passing the guide pole 10 through this U-groove, the zoom lens movable frame 11 is prevented from rotating. Reference numeral 16 denotes a cam frame provided between the main body 1 and the door frame 8. This cam frame 16 is provided with a helical groove, and a guide provided at the lower end of the zoom lens moving frame 11 is inserted into this helical groove. When the pin 33 is fitted and the cam frame 16 is rotated, the zoom lens movable frame 11 is regulated by the helical groove of the cam frame 16 and is movable in the direction of the optical axis 17. 18
are teeth provided at the end of the cam frame 1e. Reference numeral 19 denotes a motor section attached to the upper end of the main body 1. The gear section attached to the tip of the shaft of this motor section 19 and the tooth section 18 mesh with each other, so that the rotation of the shaft of the motor section 19 is caused by the rotation of the shaft of the motor section 19.
As the cam frame 16 rotates as a result of the rotation of the cam frame 16, the zoom lens moving frame 11 moves in the direction of the optical axis 17. Reference numeral 20 denotes an iris portion that performs an aperture operation, 21 a master flange fixed to the 3-door frame 8, and 22 a master flange whose both ends fit into the master flange 21 and the 3-door frame 8, respectively, so as to be parallel to the optical axis 17. A plurality of guide poles 23 are provided on the guide poles 22, and the upper and lower ends thereof are supported by the focus lens moving frame, and the lenses 24, 25, .
26 is fixed.

Reference numeral 28 denotes a focus motor, and a mounting bracket for mounting the focus motor 28 is fixed to one of the outer sides of the frame 28a, and the upper surface of the mounting frame 2a& is fixed to the outer side of the master flange 21. The threaded shaft 28b of the focus motor 28 (engages with the d-nut 29, and this nut 29
The upper end engages with the lower end of the focus lens moving frame 23.

Further, a portion of the mounting frame 28a is partially cut out in the direction of the optical axis 17 at the center of the upper surface of the frame 28a, and at the center of the surface of the master flange 21 that fixes the mounting frame 28a on the upper surface. In the attachment, both end surfaces cut out on the upper surface of the frame 28a function to suppress rotation of the focus lens moving frame 23 engaged with the nut 29. Therefore, when the screw shaft 28b of the focus motor 28 rotates, the focus lens moving frame 23 can move in the direction of the optical axis 17 together with the nut 29 that meshes with the screw shaft 28b. 3o is a variable magnification sensor,
The sliding portion provided on the variable power sensor 3o is integrally coupled with the lower end of the guide pin 33, and the guide pin 33 is inserted along the slit groove 46 provided in the lower center of the outer frame of the main body 11. , can be moved in the direction of the optical axis 17 integrally with the zoom lens moving frame 11.

31 is a CCD fixed to the end of the master flange 21
A focus sensor 32 is provided outside the upper end of the master flange 21, and although not shown in detail, it functions to specify the initial position (origin) of the focus lens moving frame 23 when the power is turned on. Reference numeral 46 indicates a gap between the main body 1 and the variable power sensor 3°. Note that the lens barrel includes a control section (not shown) that processes a detection signal from the variable magnification sensor 30 and sends a control signal during focusing.

The operation of the lens driving device configured as described above will be described below.

When the power of the apparatus is turned on, first, the focus lens moving frame 23 confirms a predetermined initial position (origin) using the focus sensor 32. Next, the position of the zoom lens moving frame 11 is checked by the variable magnification sensor 30, and a detection signal of the position is sent from the variable magnification sensor 3o to the control section.The control section processes the detection signal and sends the control signal to the focus motor 28. sent to. The screw shaft 28b of the focus motor 28 rotates by the amount of rotation determined by this control signal, and the focus lens moving frame 23 engaged with the nut 29 that meshes with the screw shaft 28b moves in the direction of the optical axis 17, thereby moving the CCD unit 31. The image is in focus. This completes the initial settings.

Next, when zooming is performed, first, a signal for zooming is sent to the motor section 19, the shaft of the motor section 19 rotates, and this rotation meshes with a gear section attached to the tip of the shaft of the motor section 19. This is transmitted to the tooth portion 18, and the cam frame 16 rotates.

Then, the guide pin 3 fitted into the helical groove of the cam frame 16
A zoom lens moving frame 11 coupled to the upper end of the zoom lens 3 slides on the guide pole 1o. Moving frame 1 for zoom lens
1 moves, the amount of movement is detected by the variable magnification sensor 30, and a detection signal is sent from the variable magnification sensor 30 to the control section. When the control unit processes this detection signal and sends a control signal to the focus motor 28, the focus motor 28 rotates by the amount of rotation determined by the control signal, and the focus lens 28 engages with the nut 29 that engages with the screw shirt 28b. Moving frame 2
3 moves in the direction of the optical axis 17, the focus is corrected so that the CCD section 31 is in focus, and the focusing is completed.

Problems to be Solved by the Invention However, in the above conventional configuration, a slit groove is provided in the main body 1 so that the zoom lens moving frame 11 engaged with the guide pin 33 coupled to the variable power sensor 30 can move in the direction of the optical axis 17. 45, and there is a gap 46 between the main body 1 and the variable magnification sensor 3o, so the slit groove 4
6, outside air enters the lens barrel from the gap 46 through the slit groove 45, causing dust to get into the lens barrel, or causing condensation due to rapid changes in environmental temperature, causing the lens to become cloudy. occurs.

The present invention solves the above-mentioned conventional problems, and aims to provide a structure that isolates the inside of the lens barrel from the outside air.

Means for Solving the Problems In order to solve the above problems, the lens driving device of the present invention includes a main body forming a part of the outer frame of a lens barrel, a plurality of guide poles supported by the main body, a zoom lens movable frame that is movable by fitting into the guide pole and fixes a variable magnification lens group; a slit groove provided in the optical axis direction below the outer frame of the main body;
a rib formed so as to extend downward along the periphery of the slit groove engages with the zoom lens moving frame;
and a variable power sensor fixed to the end surface of the rib and covering the slit groove.

Operation With this configuration, the lens is driven, and since the variable power sensor always covers the slit groove, when the zoom lens moving frame engaged with the variable power sensor moves in the optical axis direction, the lens barrel Inside and outside air are cut off. Therefore, it is possible to take stable pictures without dust getting into the lens barrel or with the lens fogging up due to sudden changes in environmental temperature.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a lens barrel including the lens driving device of this embodiment, and is a cross-sectional view SS' of FIG. 2, which is an enlarged cross-sectional view taken in the direction of arrow B in FIG. Components in FIG. 1 having the same configuration as the conventional configuration shown in FIG. 4 are given the same reference numerals and their explanations will be omitted.

In FIG. 1, a gear part 36 is provided at the tip of the shaft # of the motor part 19 so as to fit into a shaft grip, and one side of the screw shaft 34 fitted to the main body 41 and the third door frame 8. A gear portion 3 provided on the side to fit into a screw shaft 34
It meshes with 6.

FIG. 2 is an enlarged cross-sectional view taken in the direction of arrow B in FIG.
The SS' sectional view corresponds to FIG. In FIG. 2, the motor section 19 is omitted. The following description will be made with reference to FIG. 2 as well.

A straight line connecting the centers of the threaded shaft 34 and the guide pole 10 has an inclination of approximately 45 degrees with respect to the vertical direction, and a portion of the upper end engages with the threaded shaft 34 to form the guide pole/L/
1o and a part of the lower end are fitted together, the zoom lens moving frame 37 has a shape in which only the peripheral portion including the screw shaft 34 and the guide port/L'10 is stretched out in the centrifugal direction, and the other portion has a diameter. A retaining portion 38 is formed which is small and extends downward from the vertically lower central portion. Furthermore, the lenses 12, 13, and 14 constituting the variable magnification lens group 15 are fitted in the center of the zoom lens moving frame 37. Further, a slit groove 46 is formed in the vertically lower central portion of the main body 41 in the optical axis direction, and a rib 47 that is integrally molded with the main body 41 and extends downward is formed around the slit groove 45. 40 is a rectangular parallelepiped variable magnification sensor, which contacts the upper end surface of the variable magnification sensor - 40FilF multiplier sensor 40;
A metal plate 49 covering the end surface of the rib 47 and a variable power sensor 4o
It has a slide portion 48 that extends upward from the inside of the lens via a metal plate 49 and can freely slide in the optical axis direction. Although not shown, the metal plate 49 is provided with a groove for the slide portion 48 to pass through so that the slide portion 48 can freely slide in the optical axis direction. The engaging portion 38 of the zoom lens moving frame 37 engages with the upper end of the slide portion 48, and the zoom lens moving frame 37 is moved by the slit groove 45 in a direction parallel to a plane perpendicularly crossing the optical axis (direction C). regulated. Further, although not shown, there may be a gap (about 50 μm) between the end face of the rib 47 and the metal plate 490 that is negligible in driving the lens due to accuracy problems in the manufacturing process.

The operation of the lens driving device configured as described above will be described below. Note that the focusing operation in this embodiment is the same as the fourth one except for the process in which the rotation of the screw shaft 34 of the motor section 19 is transmitted to the zoom lens moving frame 37.
Since this is the same as in the conventional device shown in the figure, only the process by which the rotation of the screw shaft 34 of the motor section 19 is transmitted to the zoom lens moving frame 37 will be described below.

In FIGS. 1 and 2, when the shaft of the motor section 19 rotates, a gear section 35 provided at the tip of the shaft so as to fit into the shaft rotates.
The gear portion 36 that engages with the screw shaft 34 on one side of the screw shaft 34 rotates, and the zoom lens moving frame 37 that meshes with the screw shaft 34 moves toward the optical axis 1.
Move in the direction of 7. At the same time, the slide portion 48 engaged with the retaining portion 38 of the zoom lens moving frame 37 moves in the direction of the optical axis 17 along a groove (not shown) provided in the metal plate 49 of the variable power sensor 3o. Then, the variable power sensor 30 detects the position of the zoom lens moving frame 37. At this time, as shown in FIG. 2, the zoom lens moving frame 37 engaged with the slide portion 48 moves in the direction of the optical axis 17 along the slit groove 46 provided at the lower center of the outer frame of the main body 1. But,
The variable magnification sensor 3o fixed to the end face of the rig 47 extending downward from the main body 1 via a metal plate 49 covers the slit groove, so that the inside of the lens barrel and the outside air are cut off, preventing dust from getting into the lens barrel. , the lens will not fog up due to sudden changes in ambient temperature, allowing for stable shooting.

As described above, according to this embodiment, by providing the variable power sensor 40 that covers the circumferential groove 45 of the slit groove 45 provided in the lower central part of the outer frame of the main body 41, the inside of the lens barrel and the outside air are connected. This prevents dirt from entering the lens barrel and provides a structure that prevents the lens from fogging even if there are sudden changes in environmental temperature. Therefore, stable lens driving is possible regardless of the environmental temperature.

Note that since the ribs 47 may be integrally molded with the main body 1, there is no need to increase the number of steps during manufacturing.

Effects of the Invention As described above, in the lens driving device of the present invention, by providing a sensor around the slit groove provided below the outer frame of the main body, the inside of the lens barrel and the outside air are cut off, and the lens barrel is moved. This prevents dirt from entering the lens, and the lens will not fog up even if there are sudden changes in the environment.

Therefore, stable lens driving is possible regardless of the environmental temperature.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a zoom lens barrel including a lens driving device according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view taken in the direction of arrow B in FIG. 1, and FIG. 3 is a cross-sectional view of a conventional zoom lens barrel. FIG. 4 is an enlarged cross-sectional view of the moving frame for a zoom lens taken in the direction indicated by arrows in FIG. 4, and FIG. 4 is a cross-sectional view of a zoom lens barrel including a conventional lens driving device. 1o... Guide ball, 37... Moving frame for zoom lens, 40... Variable magnification sensor, 4
1... Body, 46... Slip, Atto groove, 47
······rib.

Claims (1)

[Claims] A zoom lens that includes a main body forming part of the outer frame of a lens barrel, a plurality of guide poles supported by the main body, and a zoom lens that is movable by fitting into the guide poles and has a variable magnification lens group fixed thereto. a lens moving frame; a slit groove provided below the outer frame of the main body in the optical axis direction; a rib formed to extend downward along the periphery of the slit groove; and the zoom lens moving frame. A lens driving device comprising: a variable power sensor that engages with a frame, is fixed in contact with an end surface of the rib, and covers the slit groove.