JPS6326642A - Lens barrel for video camera - Google Patents

Abstract

PURPOSE:To vary the power of a finder optical system only by rotating one cam cylinder by providing one cam cylinder which is fitted rotatably onto the outer periphery of a photography optical system and moving a finder optical system compensating lens control pin properly associatively with the movement of a power variation lens frame. CONSTITUTION:When switching from a wide-angle side to a telephoto side is performed by a switching member on a camera side, an operation pin 43 moves from a WIDE position to a TELE position and the cam cylinder 2 where the operation pin 43 is implanted fixedly also rotates in the same direction. Consequently, the rotational directions of rollers 33 and 35 are controlled by a guide shaft 15 and a straight movement groove 3c, so they move toward TELE ends 2f and 2h along cam groove holes 2a and 2b respectively. In such case, only a lens L21 in a photographic lens system which is a variable power group moves by zooming, but the movement quantity of an image formation plane is designed within the depth of the field and wherever operation pin 43 is stopped between the wide-angle end and the telephoto side, a sharp image is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a video camera lens Sn TRI, l?
The present invention relates to a lens barrel for a video camera in which a photographing optical system and a finder optical system, which are independent from each other, are operated in conjunction with each other during a zooming operation.

[Prior Art] In a video camera, as is well known, the relationship between the photographing optical system and the finder optical system is that in the case of a zoom optical system, the CR
An EVF (electronic viewfinder) type lens system that uses a T (cold cathode ray tube) to whiten only the photographing system, and a prism placed at the rear of the G' lens for the photographic optical path and finder optical path. What to divide, also simple:
In addition to the above, fj' and point lenses can be roughly divided into three types, including those in which the photographing lens system and finder lens system are completely independent.

However, until now, there has been no known system in which the photographing lens system and the finder lens system are independent, but both optical systems can be operated to change the magnification at the same time.

[Problems to be solved by the invention] By the way, in a video camera lens barrel in which the photographing optical system and the finder optical system are independent,
It is desirable that both optical systems operate in conjunction with each other during zooming operations. However, if the two optical systems were to be interlocked only during zooming operations, such as by providing cam rings for each optical system and interlocking them, or by using levers, etc., it would simply require a large amount of space. This results in a complicated mechanism, which is a major drawback in promoting the miniaturization and weight reduction of video cameras as a whole.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lens barrel for a video camera that allows zooming to be performed by simultaneously moving both optical systems by simply rotating one cam barrel.

[Means and effects for solving the problems] The present invention has the following features:
In order to solve the above problems, we developed a photographic lens optical system that performs zooming by moving one lens group in the optical axis direction, and a system in which the optical axes of this photographic lens optical system are parallel to each other. It is arranged so that
A variable magnification finder optical system that performs magnification changing operation by moving two lens groups in the optical system in the optical axis direction; and a first cam groove rotatably provided on the outer periphery of the photographing lens optical system. a cam cylinder having a hole; a second cam slot provided in the stationary frame that fits around the outer periphery of the first movable lens group of the finder optical system; and a straight groove parallel to the optical axis; a protrusion that is integrated with the movable lens group and that fits into the linear groove and whose outer periphery fits into the first cam slot; , a third cam slot having a shape without a portion parallel to the optical axis; and the second movable lens group of the finder optical system;
and a protrusion that fits in common with the cam slot and the third cam slot.

[Example] The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a diagram showing the internal structure of a lens barrel for a video camera according to an embodiment of the present invention.
It is a sectional view along the -1 line. Figure 3 also shows ■ in Figure 1.
It is a cross-sectional view along the -■ line.

It should be noted that the left side in FIG. 1 is the hexagonal body side, and the right side is the photographer's side.

As shown in FIG. 1, the photographing lens optical system comprises a fixed lens group, a first lens group consisting of lenses Lll and L12 forming a focus group, a second lens group consisting of a lens L21 forming a variable power group. Lens L31. L32. L3
The finder lens optical system includes lenses FLII, FL12, . FL13 and FL
21. FL51 and lens FL3 that make up the variable magnification lens group
1. Lens FL41 that constitutes FL32 and correction lens group
and lens FL6 that constitutes the eyepiece group with adjustable diopter.
1. It is formed as FL62.

The entire finder lens optical system is housed in a long finder barrel 4 with a small diameter, and as shown in FIG. It is formed of a cover tube 4A in the lower half and a support tube 4B in the lower half, and a holding tube 3 for housing the photographic lens optical system is integrally formed at the lower part of the support tube 4B in the lower half near the front. has been done. Inside this holding cylinder 3, an inward flange 3a for attaching a fixed cylinder is provided near the front part of the holding cylinder 3.
A plurality of screw insertion holes are bored at equal intervals.

As shown in Fig. 1, a fixed cylinder 1 having a cam cylinder 2 (see Fig. 7) rotatably fitted on the outer circumferential surface of the holding cylinder 3 is fitted and fixed. ing. In other words, as shown in FIG.
It is integrally attached to the holding cylinder 3 by screwing in a fixing screw 37 (see FIG. 1) that overlaps the flange 3a and passes through the flange 3a. The horizontal notch 1c of the outward flange 1b is a position regulating part in the rotational direction when the fixed cylinder 1 is attached to the holding cylinder 3.

Returning to FIG. 1, a helicoid screw 1a is cut into the front inner peripheral surface of the fixed cylinder 1 fixed to the holding cylinder 3 in this way, and the outer circumference of the focus frame 6 is attached to the helicoid screw 1a. A helicoid screw 6a carved on the surface is screwed together. The focus frame 6 holds the lens groups Lll and L12 of the photographic lens optical system attached by a lens retaining ring 19 screwed in from the front, and also has a rotating protrusion 8.
It has b integrally. The lens L21, which is the second lens group of the photographic lens optical system, is fixed to the variator frame 7 by adhesive, and the variator frame 7 has a holding part 7a and a holding part 7a projecting in the radial direction, as shown in FIGS. It has a fitting part 7b.

A pipe 16 parallel to the optical axis direction is embedded in the holding portion 7a, and a pin 32 protruding in the radial direction is installed, and a roller 33 is integrally attached to the pin 32. Here, FIG. 4 shows the internal structure of the fixed frame 1 in a horizontal cross section.

As shown in FIG. 4, the pipe 16 is slidably fitted into the guide shaft 14 arranged parallel to the optical axis, and the fitting part 7b is also arranged parallel to the optical axis. The guide shaft 15 is slidably fitted into the guide shaft 15. The shafts 14 and 15 are each fixed at one end to the shaft support ring 17, and at the other end to the rear flange 1d of the fixed cylinder 1, and are suspended on both sides of the photographing optical system. The shaft support ring 17 is fitted into the regulation hole of the fixed cylinder 1, is attached to the fixed cylinder 1 by a C ring 18, and is non-rotatably fixed to the fixed cylinder 1 by a positioning portion (not shown). Further, the pin 32 and the roller 33 supported by the pin 32 pass through a linear slot 1e in the optical axis direction drilled in the fixed barrel 1, and pass through a cam slot 2a (eighth (see figure).

Returning to FIG. 1 again, lens L31 constituting the third lens group in the photographic lens optical system is fixed to one third group support frame 8 by a spring ring 20, and lens L32. L3
3 is fixed to the other third group support frame 9 by a spring ring 23 via a spacer 22. Further, between the third group support frame 8 on one side and the third group support frame 9 on the other side, a presser rubber ring 21 and an auto iris 5 are arranged as shown in FIG. 1), the auto iris 5 is fixed via the rubber ring 21. That is, both frames 8 and 9 and the auto iris 5 are integrated. The opening of the auto iris 5 is automatically and appropriately controlled by an iris motor 5a. Here, FIG. 9 is drawn upside down from FIG. 1 in order to show the screw hole 9a. Here one 3
Horizontal notch 8a of group support frame 8 and other third group support frame 9
The horizontal notches 9d each indicate a mounting relief part for the auto iris 5, and similarly the notches 8b, 8c and 9b, 9c
is a relief part of the guide shaft 14, 15, etc. shown in FIG.

The rear part of the other third group support frame 9 is fitted into the rear opening of the fixed cylinder 1, as shown in FIG. A screw hole 9a is provided. As shown in FIG. 4, a screw 36 for Fc adjustment is screwed into this screw hole 9a through an elongated hole 1f in the optical axis direction formed in the fixed tube 1. This allows minute movement of the third group support frames 8 and 9, and FC adjustment is performed during assembly.

As shown in FIG. 1, an element mounting frame 10 is fixed to the rear end of the fixed tube 1 with screws 40, and the mounting frame 10 includes a filter 11 such as a crystal filter, a presser rubber 24,
A CCD 12, which is an image sensor, is pressed and fixed by a CCD holding member 13.

Note that the CCD holding member 13 is fixed to the element mounting frame 10 with screws (not shown).

On the other hand, the cam cylinder 2 is rotatably fitted onto the outer periphery of the fixed cylinder 1. The movement of the cam barrel 2 in the optical axis direction is restricted by a cam presser 25 fixed to the outward flange 1b at the front of the fixed barrel 1 and the flange 1d of the fixed foot 1 with screws 39. As shown in FIGS. 7 and 8, the cam barrel 2 is provided with a photographing lens cam slot 2a and a finder cam slot 2b.
A roller 33 implanted in the variator frame is fitted into the portion a. This cam cylinder 2 has an operating pin 43 (see Fig. 1).
In addition to providing a screw hole 2C for fixing the auto iris 5, a notch 2d that is a relief part for the auto iris 5 is formed. Further, the operation bottle 43, which is installed in the threaded hole 2C and extends in the radial direction, is a partially arcuate hole bored in the holding tube 3 in a direction perpendicular to the optical axis, as shown in FIG. 1.6. 3b and extends outward.

Next, the arrangement of the lenses that make up the +M component of the finder optical system will be explained.As shown in FIG. 1, the fixed lenses FLII, FL12, . FL13 has the first
It is held by being pressed by the elastic claw member 26a via the spacer 29 and the second spacer 30. This fixed lens FL11. FL12. Support frame 26 holding FL13 and fixed lens FL21. The FL 51 and the field frame 31 are directly held in respective positioning grooves provided on the inner peripheral surfaces of the cover cylinder 4A and the support cylinder 4B.

Lens FL31 constituting the variable magnification lens group. The FL 32 is formed of a cemented lens and is fixed to a movable frame 27 that is a relatively long cylinder with a small diameter that is tightly fitted into the cylinder 4 so as to be slidable in the optical axis direction. That is, a hole is fixed in the middle of the movable frame 27 by a stepped portion 27a and a spring ring 42. This movable frame 27 has a threaded hole 27 near its front part.
As shown in FIG. 1.3, a pin 34, on which a roller 35 constituting a cam follower is fitted, is screwed into the threaded hole 27b so as to protrude in the radial direction. And this pin 34. The roller 35 is fitted into a linear groove 3c in the optical axis direction formed in the support cylinder 4B and a finder cam groove hole 2b formed in the cam cylinder 2 (see FIGS. 7 and 8). Further, as shown in FIG. 6, the moving frame 27 is provided with a cam groove hole 27'c for a correction lens at a symmetrical position at an angle of 1800 with respect to the optical axis.

On the other hand, a correction frame 44 made of a small-diameter short cylinder is fitted into the inner circumferential surface of the movable frame 27 so as to be movable in the optical axis direction, and the hli positive lens 41 is attached to the correction frame 44 by adhesive. Fixed. As shown in FIG. 1, the correction frame 44 has a pin 45 fitted with a roller 46 that passes through the correction lens cam groove hole 27C (see FIG. 6) and is screwed into the screw hole 44a. installed.

Further, the roller 46 and pin 45 that pass through the correction lens cam slot 27c protrude outward, and the protruding end further extends from the i? e+1 bar tube 4A
The correcting cam grooves 4d and 3h are respectively fitted symmetrically into the supporting cylinder 4B. Here, the finder cam slot 2b constitutes a first cam slot 113 in the present invention, the correction cam slots 4d and 3h constitute a second cam slot, and the correction lens cam slot 27c , 27c
Each of the third cam slots has 14 holes.

On the other hand, as shown in FIG. 1, lenses FL61. FL62 is composed of a cemented lens,
It is held by an elastic claw member 28a in a diopter frame 28 fitted to the inner circumferential surface of the cylinder 4 near the end on the photographer's side so as to be slidable in the optical axis direction.

The diopter frame 28 is integrally formed with diopter adjustment pins 23b and 28b that protrude outward at symmetrical positions, and the pins 23b and 28b are attached to the cover of the diopter frame 28, as shown in FIGS. A diopter adjustment cam'/R hole 4a is formed in the tube 4A and the support tube 4B, respectively.

It is inserted into 4a.

In this way, the entire finder lens optical system is held by the cover tube 4A and the support tube 4B.

In addition, the cover tube 4A and support tube 4B that sandwich the finder lens system are integrated into the support tube 4B by fixing the cover tube 4A to the support tube 4B at multiple locations with screws 41, as shown in FIGS. 3 and 6. When the cover cylinder 4A and the support cylinder 4B are integrated, uneven portions 3e and 3 formed at both ends of the cover cylinder 4A and the support cylinder 4B are formed.
d.

3f, 3g, 4c, and 4b are positioning parts.

Further, when the fixed cylinder 1 and the holding cylinder 3 are fixed as shown in FIG. The movement of the roller 35 in the rotational direction is regulated by a rectilinear groove 30 parallel to the optical axis bored in the support tube 4B, and the movement in the direction of the optical axis is regulated by a first cam groove hole 2b provided in the cam tube 2. has been done. Further, an operating pin 43, which is equivalent to the cam cylinder 2, passes through an arcuate hole 3b provided in the holding cylinder 3 and can be interlocked with an external operating member (not shown).

The photographing lens optical system and the finder lens optical system configured in this manner are fixed to the video camera body (not shown), and the CCD 12° auto iris 5 and the like are connected to the camera body side by appropriate means.

Next, the lens movement effect in the lens barrel of the above embodiment will be described. FIG. 1 shows a state where the focal length is wide (wide angle) and the photographing distance is infinite.

When focus adjustment is performed in this state, the rotating protrusion 6b, which is integral with the focus frame 6, is moved in the rotating direction by an interlocking member (not shown). Since the focus frame 6 is held in the fixed barrel 1 by helicoid screws 6a and la, the focus frame 6 moves forward in the optical axis direction with respect to the fixed barrel 1 by rotation, and thereby the focus frame 6 moves forward in the optical axis direction with respect to the fixed barrel 1. Lens L1
Focusing of the photographic lens is performed by moving 1°L12. Focusing in this embodiment is so-called zone focusing in which the stopping position is determined at a power point.

On the other hand, in the finder optical system, diopter adjustment is performed by rotating a diopter adjustment pin 28b, which is integrated with the diopter frame 28, by an operation member (not shown) and moving within the diopter adjustment cam slot 4a. At this time, the finder optical system is not linked to the focusing operation of the photographic lens optical system, and a focused image is always visible within the finder.

Also, during shooting, the iris motor 5a may be
The CCD 12 is always supplied with an appropriate amount of light by the auto iris 5.

Next, the operation when zooming the focal length from wide to tele (telephoto) will be explained.

When switching from wide to telephoto is performed by a switching member (not shown) on the camera side, the operating bin 43 moves from the WIDE position to the E position in FIG. 3. As a result, the cam cylinder 2, which corresponds to the operating bin 43, also rotates in the same direction.

A roller 33 that controls the magnification of the photographic lens and finder lens. When the roller 35 is wide, the roller 35 is at the WIDE end 2e of the photographic lens cam slot 2a and the finder cam slot 2b in FIG. 8, respectively.

It is located at 2g.

Therefore, when the cam cylinder 2 rotates as described above, the roller 3
3. Since the rotational direction of the roller 35 with respect to the optical axis is regulated by the guide shaft 15 and the linear groove 3C, the roller 35 moves toward the position E ends 2f and 2h along the cam groove holes 2a and 2b, respectively. At this time, in the photographic lens system, only lens L21, which is a variable power group, moves due to zooming, but the movement of the imaging plane by this is designed to be within the depth of field, and it changes from wide to tele. A clear image can be obtained no matter where the operating bin 43 is stopped.

Further, the finder system lens is a variable a)) lens FL31. fixed to the movable frame 27 through the cam slot 2b. F
L32 is moved, but variable magnification lens FL31. FL
If only 32 is moved, the amount of image plane movement is large, and it is difficult to use it at an intermediate position like a photographic lens. Therefore, the lens FL41 is arranged as a correction group in the finder optical system,
The image plane is always kept constant.

This correction lens FL41 and variable power lens FL31°FL3
2 will be explained based on the cam development diagrams shown in FIGS. 10 and 11. In FIG. 10.11, the lower side shows the subject in a wide-angle state, that is, the state in FIG. 1.

The roller 35 is integrated with the moving frame 27 and is inserted into the cam slot 2 of the cam cylinder 2.
b and the straight groove 3C of the holding cylinder 3.

The roller 46 is integrated with the correction frame 44, and is connected to the cam slot 27c of the moving frame 27 and the cam slot 3 of the support cylinder 4B (cover cylinder 4A).
It is regulated by h(4d). When a zooming operation is performed in this state, the cam cylinder 2 rotates in the direction of the arrow, and the cam slot 2b also rotates, so the roller 35, that is, the movable frame 27 moves along the straight groove 30. This moving frame 2
7, the cam slot 27c also moves upward in FIG. 10 parallel to the straight groove 3c. As a result, roller 46
That is, the correction frame 44 is connected to the cam slot 3h provided in the support cylinder 3.
, and at the E end, the state is as shown in FIG. 11.

The above-described effects provide a finder optical system in which the image plane is constant at any position from wide to telephoto.

Furthermore, the telephoto infinity state shown in FIG. 2 corresponds to the state in which the lens has moved to the telephoto end position in FIG. 11.

Note that focusing is performed in the same way as in wide-angle in any range other than wide-angle.

[Effects of the Invention] As described above, the present invention provides a lens barrel that simultaneously changes the magnification of the photographing optical system and the finder optical system through a zooming operation. A cylinder is provided, a cam groove for the photographing lens and a cam groove for the viewfinder lens are drilled in the cam cylinder, and a photographing optical system variable magnification lens regulating pin is inserted from inside the cam cylinder.
Also, the finder optical system variable magnification lens regulating pins are inserted into the respective cam grooves from the outside of the cam cylinder, and the finder optical system correction lens regulating pins are moved as appropriate in conjunction with the movement of the variable magnification lens frame. As a result, the viewfinder optical system, which is disposed parallel to the photographic optical system, can be changed in magnification by simply rotating a single cam barrel, without using any interlocking members such as levers, and the overall size of the video camera can be reduced. Therefore, it is possible to provide a lens barrel for a video camera that is lightweight.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a video camera lens barrel showing an embodiment of the present invention, taken along the line II in FIG. 3. FIG. 2 is a sectional view of the lens barrel shown in FIG. 1 above. Fig. 3 is a sectional view taken along the line ■-■ in Fig. 1 above, and Fig. 4 shows the variable magnification lens supported. Figure 5 is a cross-sectional view showing the moving mechanism of the variator; Figure 5 is a perspective view showing only the fixed barrel taken out from Figure 1 above; Figure 6 is a viewfinder barrel and lens holder from Figure 1 above. FIG. 7 is an exploded perspective view showing only the cam cylinder taken out from FIG. 1, FIG. 8 is an exploded view of the main parts of the cam cylinder, Figure 9 is an exploded perspective view showing only the third group support frame taken out from Figure 1 above. It is. L21......One lens group 1...
・・・・・・・・・・・・Fixed tube 2・・・・・・・・・・
・・・・・・・・・Cam tube 2b・・・・・・・・・・
...Finder cam slot (first cam slot) 3...Holding tube (immovable frame) 3C...・・・・・・・・・Straight groove 3h,
4d...Correction cam slot (second cam slot) 4.
・・・・・・・・・・・・・・・Finder barrel (immovable frame) 27c・・・・・・・・・Cam slot for correction lens (third cam slot ) Square 5 Square 8 Figure

Claims (1)

[Claims] A photographic lens optical system that performs zooming by moving one lens group in the photographic optical system in the optical axis direction, and a photographic lens optical system arranged so that the optical axes of the photographic lens optical system and the photographic lens optical system are parallel to each other. hand,
A variable magnification finder optical system that performs magnification changing operation by moving two lens groups in the optical system in the optical axis direction; and a first cam groove rotatably provided on the outer periphery of the photographing lens optical system. a cam cylinder having a hole; a second cam slot provided in the stationary frame that fits around the outer periphery of the first movable lens group of the finder optical system; and a straight groove parallel to the optical axis; a protrusion that is integral with the movable lens group and that fits into the linear groove and whose outer periphery fits into the first cam slot; and a protrusion that is integral with the first movable lens group and that A third cam slot having a shape without a portion parallel to the axis; and a second movable lens group of the finder optical system;
A lens barrel for a video camera, comprising: a protrusion that fits in common with the cam slot and the third cam slot.