JPS5930242B2 - Zoom lens structure - Google Patents

Description

[Detailed description of the invention] The present invention relates to a zoom lens structure.

A typical zoom lens has one cam ring with a cam groove for the variable power lens and a cam groove for the correction lens, and when the variable power lens is moved by rotation of the cam ring, the correction lens is not connected. It is well known that the lens is configured to be moved to change the distance from the variable magnification lens to correct focal shift.
In such a zoom lens, if there is play between the shaft screw of the lens moving ring and the cam groove, an error will occur in the distance between the variable power lens and the correction lens.

In order to prevent such errors, various measures have been taken, such as using a spring to constantly press the shaft screw of the movable ring against one side of the cam groove. On the other hand, even if there is diametrical backlash between the cam ring and the fixed lens barrel, when the cam ring is rotated, the cam ring moves diametrically within the fixed lens barrel, causing the movable ring to fit into the cam groove. It is moved and displaced in the optical axis direction.

The direction of movement of this cam ring varies depending on the position and direction of the point of action. Therefore, in cameras capable of automatic zoom operation using a motor and manual zoom operation, the state of pit misalignment differs between automatic and manual zoom operations, and may also change depending on the direction of zoom operation. be. In general, in a zoom lens configuration in which the correction lens moves back and forth during zoom operation and takes approximately the same position on the telephoto side and the wide side, pits may appear when the variable magnification lens is deviated from its normal position on the telephoto side. The deviation is significant.

The present invention attempts to prevent pit misalignment by moving the variable magnification lens in the optical axis direction by moving the cam ring in the diametrical direction to the maximum in both automatic and manual operations.

The present invention will be explained in detail below with reference to the drawings.

Fig. 1 is a perspective view showing the front part of a camera to which the present invention is applied, where 1 is the camera body, 2 is a distance ring, 3 and 4 are electric zoom operation buttons; The focal length changes toward the telephoto side. 5 is a knob for changing the speed of the electric zoom and switching between manual zoom and electric zoom, 6 is a zoom ring having a manual zoom lever 1, 8 is a cam ring, and Ba is a gear fixed to the cam ring.

Reference numeral 9 is a contact piece attached to the switching knob, which slides on contact patterns 10a to 10d provided on the printed circuit board 10 to switch the zoom speed between H, L, and N.

M is a zoom drive motor; 14 is a gear fixed to the output shaft of the motor; 18 is a gear that constantly engages with the gear 8a of the cam ring; and 45 is a gear that engages with the gear 14 and engages with and disengages from the gear 18 via the clutch 44. , 11 is a clutch lever for disengaging the clutch 44 during manual zoom operation.

2 is a cross-sectional view of the zoom lens barrel, and FIG. 3 is an exploded perspective view. Reference numeral 22 denotes a fixed lens barrel fixed to the camera body 1, which has a helicoid screw 22a on its outer periphery, and is integrated with the distance lens 2. A focusing lens barrel 20 is screwed and held.

19 indicates a focusing lens.

The cam ring 8 is rotatably fitted into a fixed lens barrel 22, and its movement in the optical axis direction is restricted by a ring 21 fixed to the rear end wall and front end of the fixed barrel.

Cam grooves 8b and 8c are provided on the outer periphery of the cam 8, and pins 27 and 30 implanted in movable rings 25 and 28 that hold the variable power lens 26 and the correction lens 29 are fitted into the cam grooves, respectively. These movable rings fit into the linear guide bars 23a, b, c.
When the cam ring 8 rotates, it moves in the optical axis direction according to the cam grooves 8b and 8c, respectively.

Reference numeral 24 denotes a connecting pin screwed to the zoom ring 6 which rotatably fits on the outer periphery of the fixed cylinder 22, and whose tip passes through the groove 22c of the fixed cylinder and fits into a straight groove 8d provided in the cam ring 8. The rotation of the zoom ring is transmitted to the cam ring 8.

The present invention will be explained in comparison with a conventional example in a zoom lens configured as described above.

FIG. 4 shows the relationship between the connecting pin 24, the electric zoom gear 18, and the cam grooves 8b and 8c in a conventional example.

Rotate the zoom ring 6 in the direction of arrow A using the zoom lever 7,
The pin 2 fits into the long groove 8d when the connecting pin 24 is brought into contact with the end 22d of the groove 22c of the fixed lens barrel at the telephoto end.
4, the cam ring 8 receives a force in the direction of arrow P1 at the long end 8d1 of the long groove.

On the other hand, since the gear 8a meshes with the zoom gear 18, it receives a force P2 in a direction inclined by a pressure angle with respect to the tangent to the pitch circle due to the load of the gear. These forces P, , P2 are equal to each other, and this resultant force P pushes the cam ring 8 in the direction of arrow P within the play between it and the fixed cylinder. Further, FIG. 5 shows the case of electric zoom.

When the gear 18 rotates in the direction of arrow B and rotates the cam ring 8 toward the telephoto end, force is transmitted to the connecting pin 24 by the lower end 8d2 of the long groove to rotate the zoom ring 6. The figure shows a state in which the pin 24 is in contact with the telephoto end, and the lower end portion 8d2 of the long groove receives a reaction force in the direction of arrow Q2 due to a load from the zoom ring or the like. Further, the cam ring gear 8a receives a force in the direction of arrow Q1 due to the rotation of the zoom gear 18. Therefore, as in the case of manual zoom, the cam ring 8
is pushed in the direction of arrow Q by the resultant force. There is a difference between the fixed lens barrel 22 and the cam ring depending on the machining accuracy, but it is difficult to completely eliminate play.

As shown in FIG. 3, the movable rings 25 and 28 have sleeves 25a and 28a fitted into guide bars 23b and 23c, respectively, and are supported by three guide bars together with other elongated holes. Therefore, if the play in the fitting part is negligible, when the cam ring 8 is moved by the resultant forces P and Q as described above, the cam ring 8 will move relative to the movable rings 25 and 28 by an amount corresponding to the play. Be eccentric. At this time, the cam groove 8c for the correction lens does not have much inclination at its end, so the pin 30 hardly receives the movement of the cam ring 8, but the cam groove 8b for the variable power lens is inclined at the telephoto end. Since the pin 27 is strongly provided in a direction close to perpendicular to the direction of movement of the cam, the pin 27 is directly affected by the movement of the cam ring and moves in the optical axis direction. For this reason, the distance between the variable magnification lens 26 and the correction lens differs between manual operation and electric operation, and a pit shift occurs in either case. In addition, when the zoom lug 6 is turned in the opposite direction to the arrow A in Fig. 4, the cam ring 8
moves in response to the resultant force in the same direction as Q shown in FIG. 5, causing pit displacement as in the case described above.

In order to prevent the variable magnification lens from moving at the telephoto end as described above, the present invention is configured so that the connecting pin 24 and the long groove 8d are close to the zoom gear 8 when the cam ring rotates to the telephoto end.

FIGS. 6 and 7 show the direction of movement of the cam lug in such an arrangement.

FIG. 6 shows the case of manual zooming. When the zoom ring 6 is rotated in the direction of arrow A and reaches the telephoto end, the long groove 8d is fixed to 1/2 by the connecting pin 24 in the same way as explained in FIG. 4. It receives a force and also receives a reaction force in the direction due to the load of the gear.

Therefore, the resultant force y acts in the direction shown by the arrow. FIG. 7 shows the case of electric zoom, in which the gear 18 rotates in the direction of arrow B, and the gear 8a that meshes with this receives a force in the direction of Q, and the long groove portion 8d presses against the zoom ring 6, which is a load. ′! receives a reaction force in the Q4 direction.

Therefore, the cam ring 8 moves in response to the resultant force in the direction of the arrow q. The resultant force acts in the same direction in both the case of FIG. 6 and the case of FIG. 2
7 will not be affected.

In this case, the pin 29 is affected by the movement of the cam groove 8c, but as described above, almost no movement occurs in the optical axis direction. As described above, the present invention provides a zoom lens structure in which a cam ring is connected to a zoom ring by a connecting pin, and the cam ring is connected to a motor via a gear, allowing manual zoom and electric zoom. In addition, since the part that transmits the rotational force to the cam ring in the case of manual zoom operation and the part that transmits the rotational force to the cam ring in the case of electric zoom are almost the same near the zoom end, it is possible to In this case, the cam ring will move in a fixed direction near the telephoto end within the play between it and the fixed lens barrel, and the position of the pin of the variable magnification lens moving ring should match that direction at the telephoto end. By doing so, it is possible to obtain a zoom lens in which no error occurs in the distance between the variable power lens and the correction lens in both electric zooming and manual zooming.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the external appearance of a camera equipped with the zoom lens structure of the present invention, Fig. 2 is a sectional view of the zoom lens structure, Fig. 3 is a perspective view of the same, and Fig. 4 is a conventional example during manual zooming. 5 is an explanatory diagram showing the moving direction of the cam ring during automatic zoom in the conventional example. FIG. 6 is an explanatory diagram showing the moving direction of the cam ring during manual zoom in the present invention. FIG. 7 is an explanatory diagram showing the moving direction of the cam ring during automatic zooming in the present invention. 1: Camera body, 2: Distance ring, 3, 4: Automatic zoom operation button, 6: Manual zoom operation ring, 8: Cam ring, 8b: Cam groove for variable magnification lens, 8c: Cam groove for correction lens, 22: Fixed lens barrel, 24 Two connecting pins, 25: Variable lens moving ring, 26
: variable magnification lens, 27: pin, 28: correction lens moving ring,
29: variable magnification lens, 30: pin.

Claims (1)

[Scope of Claims] 1. It is rotatably fitted into the fixed lens barrel and is also engaged with the variable magnification lens moving ring and the correction lens moving ring through cam grooves, and the rotation moves both said moving rings. A cam ring that is moved in a constant relationship, a transmission means that transmits the rotational force of the manual zoom operation member to the cam ring, and a gear that meshes with the cam ring and transmits the rotation of the automatic zoom operation motor to the cam ring. 1. A zoom lens structure characterized in that the transmission means is located at a position that substantially coincides with the gear when the cam ring is rotated to the telephoto side end. 2. The lens according to claim 1, wherein the engagement position of the variable power lens moving ring and the cam groove is located near an extension of a line connecting the gear and the optical axis. Zoom lens structure.