JP2959717B2 - Retractable zoom lens barrel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retractable zoom lens barrel, and more particularly, to a zoom lens barrel capable of shortening the length of the barrel when not in use. 2. Description of the Related Art A collapsible camera has already been proposed (see JP-A-57-94734 and JP-A-59-22039).
There has not been proposed any zoom lens that can reduce the length of the lens barrel when not in use. In general, the conventional zoom lens barrel, as shown in Figure 6-Figure 8, on the fixed barrel 21, a focusing cam frame 30 and zoom cam frame 25, a relay lens frame holding the relay lens L ₄ It is provided rotatably between 22 and the holding frame 33. The pin 29a of the focusing lens frame 29 which holds a focusing lens L ₁ is fitted to 30a of the cam groove of the linear groove 21a and the focusing cam frame 30 of the fixed barrel 21, by rotating the focusing cam frame 30 The focusing lens frame 29 moves back and forth in the optical axis direction. Further, the variator frame holding the variator lens L ₂
Pin 23a of the compensator frame 23 holding the pins 24a and compensator lens L ₃ of the 24 linear grooves 21b of the fixed barrel 21
Are fitted into the cam grooves 25a and 25b of the variable magnification cam frame 25, respectively.By rotating the variable magnification cam frame 25, the variator frame 24 and the compensator frame 23 are respectively moved by a predetermined amount in the optical axis direction. Go to That is, the variable magnification cam frame 25
The variator frame 24 and the compensator frame 23 are moved between the short focus side (wide) position shown in FIG. 6 and the long focus side (tele) position shown in FIG. Is shifted. [Problems to be Solved by the Invention] As is clear from the configuration of the zoom lens barrel, the conventional zoom lens barrel has the same length as the lens barrel when in use and the lens barrel when not in use. And the lens barrel is not shortened when not in use. Therefore, it is inconvenient for carrying and storing. SUMMARY OF THE INVENTION It is an object of the present invention to provide a retractable zoom lens barrel in which the length of the lens barrel can be shortened when not in use so as to be convenient for carrying and storing. [Means and Action for Solving the Problems] The collapsible zoom lens barrel according to the present invention is arranged closer to the image plane side than the front group lens, with the optical axis common to the front group lens. It consists of a lens group other than the front group lens, and as the front group lens changes from the normal use position to the shortened position, the lens groups other than the front group lens are also allowed to be displaced to the shortened position. A collapsible zoom lens barrel having a lens holding mechanism, a front lens holding mechanism for holding the front lens, a holding mechanism for holding a lens group other than the front lens, A rotating cam mechanism for displacing the front lens group in the optical axis direction and a holding mechanism for holding a lens group other than the front lens group include a lens group other than the front lens group and Light towards the cam surface A spring-like elastic body that expands and contracts in the optical axis direction to apply a biasing force in the direction and to allow a lens group other than the front group lens to change to the shortened position in accordance with the change of the front group lens to the shortened position. When,
And a driving mechanism for displacing the lens holding mechanism. [Embodiment] FIGS. 1 and 2 are sectional views of a retractable zoom lens barrel showing an embodiment of the present invention, and FIG. 1 shows a non-use state.
FIG. 2 shows the state of use. FIG. 3 is an exploded perspective view of the zoom lens barrel. In the first to third diagram, relay lens frame 2 which holds the relay lens L ₄ is fixed to the flange portion 1c of the rear end of the fixed barrel 1, it is immobile relative to the camera body not shown. The fixed cylinder 1 has an optical axis O
Are formed in parallel with the optical axis O. Two guide bars 1d and 1e are provided on the front surface of the flange portion 1c. The inside of the fixed tube 1 variator frame 4 is fitted movably holding the compensator lens L ₃ a compensator frame 3 holding the and variator lens L _2. The compensator frame 3 and the variator frame 4 are each provided with three frame plates of the same shape long in the optical axis direction at equal angular intervals, and a portion with and without a frame plate is arranged every 60 °. They have the same diameter. And
The compensator frame 3 and the variator frame 4 are configured such that the respective frame plates are fitted into portions without a frame plate in the opposite direction so that the compensator frames 3 and the variator frames 4 can move closer to or away from each other in the optical axis direction. Further, the materials of the compensator frame 3 and the variator frame 4 are selected so that they can slide smoothly with each other and also with respect to the fixed cylinder 1. Pins 3a and 4a as cam followers are implanted at positions near the rear ends of the compensator frame 3 and the variator frame 4, respectively. The pins 3a are fitted into the key grooves 1a above the fixed cylinder 1. However, the pin 4a is fitted in the lower keyway 1b. A variable magnification cam frame 5 is rotatably fitted on the outer peripheral surface of the fixed cylinder 1. As shown in FIG. 4, the variable-magnification cam frame 5 projects rearward and has the keyway above the left and right position regulating portions 5c and 5d whose front ends are in contact with the front surface of the flange portion 1c of the fixed cylinder 1. A compensator cam surface 5a is formed at an upper position opposed to the pin 3a fitted to 1a, and the position regulating portions 5c, 5
A variator cam surface 5b is formed below d, at a lower position facing the pin 4a fitted in the key groove 1b. A retaining ring 6 is fixed to the front end surface of the fixed cylinder 1 by an appropriate means such as bonding.
Between the holes 6a, 6b formed above and below the pins 3a, 4a
Since the compensator frame 3 is always stretched, the compensator frame 3 is always urged by the spring 7 in the direction in which the pin 3a comes into contact with the compensator cam surface 5a, and the variator frame 4 has the pin 4a The variator is biased in a direction in which the variator comes into contact with the cam surface 5b. Variator lens L ₂ of the focusing lens frame 9 which holds the focusing lens L ₁ which is disposed in front, the two upper and lower elongate rearward in parallel to the optical axis O frame plate 9a, 9b
These frame plates 9a, 9b are arranged between the guide rods 1d, 1e and the fixed cylinder 1, respectively, and are inserted through the rising portions at the rear ends of the rear ends of both frame plates 9a, 9b. The guide rods 1d, 1e penetrate the holes 9d, 9e, respectively. The lower insertion hole 9
e is an elliptical shape that is slightly long in the vertical direction so that the focusing lens frame 9 can move smoothly even if there is a slight error between the dimension between the guide rods 1d and 1e and the dimension between the insertion holes 9d and 9e. It has become. A focusing cam frame 10 is disposed outside the fixed cylinder 1, and a rear end of the cam frame 10 is rotatably attached to a flange 1 c of the fixed cylinder 1. Into the cam groove 11 formed in the focusing cam frame 10, a pin 12 planted at the rising portion at the rear end of the upper frame plate 9a of the focusing lens frame 9 is fitted. As shown in FIG. 5, the cam groove 11 is continuous with the focusing cam portion 11a and the cam portion.
It is composed of a collapsible cam portion 11b whose inclination is steeper than the cam portion, and a surplus cam portion 11c which is continuous with the cam portion and substantially parallel to the circumferential direction. On the front end faces of the guide rods 1d and 1e, female threads 1f and 1g corresponding to the upper and lower screw holes 13a and 13b of the ring 13 are cut, and the ring 13 is screwed to secure the front ends of the guide rods 1d and 1e. It is fixed to the surface. The outer peripheral edge of the ring 13 abuts on a step on the front end surface of the focusing cam frame 10 to rotatably support the front end portion of the cam frame 10. The ring 13 may be fixed to the front end surfaces of the guide rods 1d and 1e by bonding or the like. Next, the operation of the thus configured zoom lens barrel will be described. The zoom lens barrel is in a state shown in FIG. 2 during normal use, and can be mounted on a camera to perform zooming and focusing. Although a drive mechanism related to zooming is not shown in the drawings, a rotation operation of a zoom frame (not shown) or rotation of a zoom motor causes, for example, a drive roller attached to the outer peripheral surface of the variable magnification cam frame 5 to rotate. The variable magnification cam frame 5 rotates. The configuration in which the driving roller is in contact with the outer peripheral surface of the variable magnification cam frame 5 is described in, for example, the focusing cam frame.
A drive roller is formed on the outer peripheral surface of the variable-magnification cam frame 5 which is notched at a position where the cam groove 11 is not formed and which is exposed at a position where the frame plates 9a and 9b of the focusing lens frame 9 are not hindered. May be attached. Alternatively, the position restricting portions 5c and 5d of the variable magnification cam frame 5 may be further extended rearward through the flange portion 1c of the fixed cylinder 1 so that a driving roller is attached to the extended portion on the camera body side. You can also. When the variable magnification cam frame 5 rotates, the pin 3a on the compensator frame 3 pressed by the spring 7 against the compensator cam surface 5a of the variable magnification cam frame 5 slides on the cam surface 5a. Is the cam surface for the above compensator
It moves in the optical axis direction according to the displacement amount in the optical axis direction of 5a. At the same time, the pin 4a on the variator frame 4 pressing the variator cam surface 5b of the variable magnification cam frame 5 with the spring 8 comes into sliding contact with the variator frame 4.
Move in the optical axis direction according to the displacement amount in the optical axis direction. Focusing is performed within a given focusing area.
By manually rotating the focusing cam frame 10 or by driving a focusing motor (not shown) as in the case of zooming, the focusing cam frame 10 is rotated.
The rotation is performed by rotating a driving roller that is in contact with the roller. That is, when the focusing cam frame 10 is rotated in the focusing area, the pin 12 on the focusing lens frame 9 moves within the range of the focusing cam portion 11a of the cam groove 11 of the focusing cam frame 10, so that the focusing lens The frame 9 is extended or retracted in the optical axis direction for focusing from close to infinity. The biasing force of the spring 7 and the pressing force of the compensator cam surface 5a are applied to the compensator frame 3 in opposite directions, but these forces are applied to the pin at the same position.
Since it is added at 3a, there is almost no rotational moment acting to tilt the compensator frame 3 with respect to the optical axis, and therefore, the compensator frame 3 slides smoothly without tilting inside the fixed cylinder 1. Since the variator frame 4 has the same configuration as the compensator frame 3,
The variator frame 4 also slides smoothly without tilting inside the fixed cylinder 1. In order to shift from such a use state to a collapsed state that is convenient for carrying and storing, the focusing cam frame 10 is further rotated from the focusing area in the direction indicated by the arrow a in FIG. That is, when the focusing cam frame 10 is rotated in the direction of the arrow a beyond the focusing area,
The pin 12 moves from the focusing cam portion 11a of the cam groove 11 of the focusing cam frame 10 to the collapsible cam portion 11b.
Since the focusing lens frame 9 moves along the inclination of 11b, the focusing lens frame 9 is similarly retracted further from the infinity focusing position. This focusing cam frame 10
Of the focusing lens frame 9
Moves backward, the lens frame 9 comes into contact with the variator frame 4 (see FIG. 1), and the variator frame 4 is moved from the same point.
Is moved further rearward than the position in the use state against the urging force of the spring 8. That is, the pin 4a on the variator frame 4 is separated from the variator cam surface 5b by this movement. When the focusing lens frame 9 and the variator frame 4 move further rearward as one unit, the variator frame 4 comes into contact with the compensator frame 3 (see FIG. 1), and the compensator frame 3 is moved from the same point as the spring. 7 is further moved rearward from the use state against the urging force of 7. Due to the movement of the compensator frame 3, the pin 3a on the compensator frame 3 is moved to the compensator cam surface 5a.
Will be separated from Thus, the focusing lens frame 9, the variator frame 4
When the compensator frame 3 is sequentially moved backward, the lens barrel of the zoom lens barrel is collapsed and shortened. When the pin 12 reaches the rearmost position of the collapsed cam portion 11b of the cam groove 11, the lens barrel is retracted. Is the most shortened state. In this state, by further rotating the focusing cam frame 10 in the direction of arrow a by a certain angle, the pin 12 moves to the extra cam portion 11c, and this zoom lens barrel is completely retracted as shown in FIG. Held in state. In this collapsed state, the lens L ₁ ~L ₄ is clog minimize spacing so as not to contact each other, the lens barrel length (amount of projection) is minimized. In order to shift from the retracted state to the use state, the focusing cam frame 9 may be rotated in the direction opposite to the direction of the arrow a to perform the operation opposite to the above-described operation. [Effects of the Invention] As described above, according to the present invention, the front lens holding mechanism and the rear lens holding mechanism are relatively urged in the optical axis direction by an elastic body, and the lens holding mechanism is provided. Is driven by a driving source such as a motor, so that the lens group can be quickly and smoothly moved to the shortened position, and the configuration is simple and the entire lens barrel can be made compact. The remarkable effect is exhibited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional side view of a retractable zoom lens barrel showing an embodiment of the present invention in a retracted state, and FIG. 2 is a retractable zoom lens mirror shown in FIG. FIG. 3 is an exploded perspective view of the retractable zoom lens barrel shown in FIG. 1; FIG. 4 is an exploded perspective view of the retractable zoom lens barrel shown in FIG. 1; 5 is a development view of a cam groove on the focusing cam frame, FIG. 6 is a longitudinal side view of a conventional zoom lens barrel in a wide state, and FIG. 6 is a vertical sectional side view of the zoom lens barrel shown in FIG. 6 in a telephoto state, and FIG. 8 is a plan view of a part of the zoom lens barrel shown in FIG. L ₁ Focusing lens (front lens group) L ₂ Variator lens (lens groups other than front lens group) L ₃ Compensator lens (〃) 1 Fixed cylinder (lens holding mechanism) 3 Compensator frame (〃) 4… Variator frame (〃) 5… Variable cam frame (〃) 9… Focusing lens frame (〃) 10… Focusing cam frame (〃)

Claims (1)

(57) [Claims] A front group lens, and a lens group other than the front group lens arranged on the image plane side of the lens with the optical axis common to the front group lens, and the front group lens is shortened from a normal use position A retractable zoom lens barrel having a lens holding mechanism that allows a lens group other than the front group lens to be displaced to the shortened position in accordance with the change to the position; A front-group lens holding mechanism, a holding mechanism for holding a lens group other than the front-group lens, a rotating cam mechanism for displacing the front-group lens in the optical axis direction, and the front-group lens A biasing force is applied to the lens group other than the front lens group toward the cam surface of the variable power cam frame in the optical axis direction to the holding mechanism for holding the lens groups other than the front lens group, and the front lens group moves to the shortened position. The front group len according to changes A spring-like elastic body that expands and contracts in the optical axis direction to allow a lens group other than a lens to change to a shortened position, and a drive mechanism that displaces these lens holding mechanisms. Type zoom lens barrel.