JP4420501B2 - Camera lens focus adjustment mode switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera lens focus adjustment mode switching device for switching between an automatic focus adjustment mode and a manual focus adjustment mode in a camera lens used in an autofocus camera.
[0002]
[Prior art]
Conventionally, as a focus adjustment mode switching device for a camera lens, it has a focus adjustment ring rotatably provided on the outer periphery of the lens barrel of the camera lens, and by moving this focus adjustment ring by a predetermined distance in the optical axis direction of the lens, The distance ring that drives the focus lens in the optical axis direction and the focus adjustment ring can be engaged and disengaged, and the manual focus adjustment (hereinafter referred to as “MF”) mode and the automatic focus adjustment (hereinafter referred to as “AF”) mode are switched. There is what I did.
[0003]
That is, when the AF mode is set, the distance ring and the focus adjustment ring are disengaged and the distance ring is rotated by AF driving means provided in the camera body or the lens barrel. When the MF mode is set, the distance ring and the AF drive are driven. The distance ring is coupled to the focus adjustment ring without being linked to the means, thereby enabling manual focus adjustment.
[0004]
In such a configuration, when the MF mode is set, the focus adjustment ring is often rotated integrally with the distance ring by elastic frictional coupling. However, when the frictional coupling force is weakened due to secular change, the focus adjustment ring is focused. There was a risk of slippage between the adjustment ring and the distance ring, and manual focus adjustment could not be performed reliably.
[0005]
In order to solve such a problem, for example, in Japanese Patent Laid-Open No. 11-23948, a series of concave portions are formed at a predetermined pitch on the inner surface of a focus adjustment ring that is rotatably mounted around a lens fixing portion. MF mode in which three pin elements that can be engaged and disengaged on the distance ring side corresponding to these recesses are provided at an angular position that is an integral multiple of the array pitch angle of the recesses, and the focus adjustment ring is in the retracted position At the time of setting, the pin element is inserted into any three of the series of recesses to transmit the rotation of the focus adjustment ring to the distance ring, and at the same time, the connection with the AF driving means on the camera body side is broken.
[0006]
[Problems to be solved by the invention]
However, in such a conventional camera lens focus adjustment mode switching device, in the MF mode, the focus adjustment ring and the distance ring are integrated by the recess and the pin element, and both are in a combined state. Switching to the mode is also possible at any rotational angle position, but if the focus adjustment ring is retracted when switching from the AF mode to the MF mode, the pin element on the distance ring side does not necessarily fit into the recess. In this case, play due to a slight reciprocal rotation of the focus adjustment ring occurs, and the operability is impaired, and there is a possibility that the shutter chance may be lost, and the configuration is likely to be complicated.
[0007]
As a modification of the above publication, any pin element can be engaged with the recess of the focus adjustment ring by making the angular intervals between the three pin elements provided on the focus lens frame unequal. A configuration is described in which the angle is reduced to solve the above problems. However, even in such an embodiment, it is not possible to couple the pin element and the recess at an arbitrary rotational angle position of the focus adjustment ring, and it is rotationally driven by one pin element that is greatly decentered from the optical axis. Distortion may occur, and the focus adjustment ring may be extremely unsmooth.
[0008]
Further, in order to prevent the focus adjustment ring from rotating when the AF mode is set, the concave portion formed on the inner peripheral surface of the focus adjustment ring by providing a knock pin by urging the lens barrel fixing portion in the outer diameter direction. In this case as well, the rotation cannot be stopped at an arbitrary position of the focus adjustment ring.
[0009]
The present invention has been made in view of the above points, has a simple structure, can switch the focus adjustment mode at an arbitrary rotation position of the focus adjustment ring with one operation, and is a focus adjustment ring in the MF mode. It is an object of the present invention to provide a camera lens focus adjustment mode switching device that does not cause play between the distance ring and between the focus adjustment ring and the lens barrel fixing portion in the AF mode.
[0010]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention can be engaged with and disengaged from the focus adjustment ring which can rotate the outer periphery of the lens barrel fixing portion around the optical axis and slide in the optical axis direction. A distance ring capable of driving the focus lens group in the optical axis direction by rotating around the optical axis, and moving the focus adjusting ring in the optical axis direction to automatically focus mode and manual focus mode In a focus adjustment mode switching device for a camera lens that can be switched between, the auto focus adjustment mode is held between the focus adjustment ring and the lens barrel fixing portion, and the lens barrel fixing portion is set when the manual focus adjustment mode is set. A focus adjustment mode switching device for a camera lens, which is provided with an O-ring that rolls from the distance ring to the distance ring and is held between the focus adjustment ring and the distance ring. A.
[0011]
In the above-described apparatus, the lens barrel fixing portion and the distance ring that are held between the O-ring and the focus adjustment ring are adjacent to each other so that the outer diameters of the adjacent portions are the same. In the above apparatus, the focus lens group may be a middle group lens or a rear group lens.
[0012]
The camera lens focus adjustment mode switching device according to the present invention is configured as described above, so that when the focus adjustment lens is moved in the optical axis direction, the O-ring rolls by friction with the held inner and outer peripheral surfaces, and light It can move freely in the axial direction, and when the AF mode is set, it is located on the lens barrel fixing part and prevents the focus adjustment ring from rotating. When the MF mode is set, the distance ring is located on the distance ring and the focus adjustment ring Rotate with.
[0013]
At this time, the O-ring can be driven with a light force in the rolling direction but cannot slide in the circumferential direction. Therefore, when the focus adjustment mode is switched, the focus adjustment ring is easily moved in the optical axis direction. When the MF mode is set, the distance ring can be rotated without slipping, and the AF mode and the MF mode can be switched without any play at any rotation angle position.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing an AF mode setting state according to an embodiment in which the present invention is applied to an inner focus lens, and FIG. 2 is a cross-sectional view showing the MF mode setting state. Only the upper half portion is shown with respect to the axis, and portions not necessarily on the same plane are also shown as the same cross section.
[0015]
The camera lens focus adjusting unit includes a lens barrel fixing unit 1 in which a bayonet mount 1f detachably attached to a camera body (not shown) is integrated at a rear end (right end in the figure), and an optical axis X attached to the outer periphery thereof. A focus adjustment ring 2 that can rotate a predetermined angle around the optical axis X and can be displaced by a predetermined distance in the optical axis X direction, and a lens barrel fixing portion 1 that is rotatably provided inside the lens barrel fixing unit 1 via a known cam mechanism. A distance ring 4 for moving the focus lens group 3 in the optical axis X direction is a main component.
[0016]
The adjacent outer peripheral surfaces 1a and 4a of the lens barrel fixing portion 1 and the distance ring 4 have the same outer diameter, and one of the outer peripheral surfaces 1a and 4a and the first circumferential groove of the focus adjustment ring 2 The O-ring 5 is held between the inner peripheral surface 2a and the O-ring 5 is rotated by friction with the held inner and outer peripheral surfaces by the movement of the focus adjusting ring 2 in the optical axis X direction (left and right in the figure). 1 and moves to the left and right by a half of the moving amount of the focus adjustment ring 2, and the position where it is stretched on the outer peripheral surface 1 a of the lens barrel fixing portion 1 shown in FIG. 1 and the outer peripheral surface of the distance ring 4 shown in FIG. 4a is a position to be stretched.
[0017]
Further, a second circumferential groove 2b is provided on the inner surface of the focus adjustment ring 2, and a bent portion 6a on the left end side of the switching lever 6 that can be displaced in the direction of the optical axis X is formed in the circumferential groove 2b. The U-shaped bent part 6b on the right end side can be displaced in the direction of the optical axis X, and engages with the left side surface of the connecting gear 8 biased to the left in the drawing by the spring 7. ing. Then, when the switching lever 6 is displaced to the left and right in conjunction with the left and right movement of the focus adjustment ring 2, the connecting gear 8 connected to the AF drive shaft 20 on the camera body side and driven to rotate is biased by the spring 7. Therefore, it is possible to move in the left-right direction against the urging force, and to engage and disengage the clutch with the drive gear 9.
[0018]
The drive gear 9 meshes with the inner surface gear portion 4b of the distance ring 4, and a pinion 11 is integrally fixed to the tip end portion (left end portion in the figure) of the center shaft 10 thereof. The connecting gear 8 that can be clutch-coupled to the drive gear 9 is connected to the camera via an intermediate gear 12 that is slidable in the axial direction and moves in the rotational direction, a pinion 13 that meshes with the intermediate gear 12, and a connecting shaft 14 that is integral therewith. It is connected to the AF drive shaft 20 on the main body side.
[0019]
The pinion 11 meshes with an inner gear portion 15a of the cam barrel 15 rotatably attached to the outer peripheral surface of the distal end portion 1d of the lens barrel fixing portion 1, and is implanted in a focus lens frame 3a integrated with the focus lens group 3. The guide pin 16 is engaged with the cam groove 15 b of the cam cylinder 15 via the roller 17. Correspondingly, a straight-groove 1e in the optical axis X direction is formed at the tip 1d of the lens barrel fixing part 1, and the cam lens 15 is rotated in both forward and reverse directions around the optical axis X, thereby focusing lens group. 3 can move forward and backward.
[0020]
Further, a click ball 18 is urged outwardly by a leaf spring 19 in the through hole 1c of the lens barrel fixing portion 1 and is loosely fitted so as to be able to roll freely. The circumferential click grooves 2c and 2d are provided, and the click ball 18 is engaged with the click grooves 2c and 2d at both ends of the movement of the focus adjustment ring 2 in the optical axis X direction. Directional positioning is performed.
[0021]
With the configuration described above, in the AF mode setting state shown in FIG. 1 in which the focus adjustment ring 2 is moved forward (leftward in the figure), the click ball 18 is engaged with the click groove 2d, and the O-ring 5 is a mirror. This position is held between the outer peripheral surface 1 a of the tube fixing portion 1 and the inner peripheral surface of the first circumferential groove 2 a of the focus adjusting ring 2. At the same time, the second circumferential groove 2b of the focus adjustment ring 2 presses the bent portion 6a of the switching lever 6 forward to move the switching lever 6 to the left, so that the restriction of the connecting gear 8 by the bent portion 6b is released. Accordingly, the spring 7 is pressed to the left by the urging force of the spring 7, and the clutch can be engaged with the drive gear 9.
[0022]
In this state, since the focus adjustment ring 2 is engaged with the lens barrel fixing portion 1 via the O-ring 5, the focus adjustment ring 2 is prevented from rotating by the frictional force of the O-ring 5 and the distance ring 4. Is separated from the O-ring 5 and can freely rotate, and the rotational driving force of the AF driving shaft 20 on the camera body side is driven via the connecting shaft 14, the pinion 13, the intermediate gear 12 and the connecting gear 8. Is transmitted to.
[0023]
Therefore, the rotation of the drive gear 9 is transmitted to the cam cylinder 15 via the central shaft 10 and the pinion 11, and the cam groove 15b moves the guide pin 16 along the straight advance groove 1e via the roller 17, and the guide pin 16 The integrated focus lens frame 3a advances and retracts the focus lens group 3 in the optical axis X direction, and the focus adjustment is automatically performed. At this time, the distance ring 4 meshing with the drive gear 9 is idling.
[0024]
In this state, the click ball 18 is engaged with the click groove 2c in the MF mode setting state shown in FIG. 1 in which the focus adjustment ring 2 is moved rearward (rightward in the figure) against the click force. Reference numeral 5 denotes a position held between the outer peripheral surface 4 a of the distance ring 4 and the inner peripheral surface of the first circumferential groove 2 a of the focus adjusting ring 2. At the same time, the second circumferential groove 2b of the focus adjustment ring 2 presses the bent portion 6a of the switching lever 6 backward to move the switching lever 6 to the right, so that the connecting gear 8 resists the biasing force of the spring 7. Driven to the right, the clutch engagement with the drive gear 9 is released.
[0025]
In this state, the rotation of the AF drive shaft 20 on the camera body side is not transmitted to the drive gear 9, and the rotation of the focus adjustment ring 2 is transmitted to the distance ring 4 without play by the frictional force of the O-ring 5. The cam cylinder 15 is rotated via the center shaft 10 and the pinion 11, and the focus lens frame 3a is moved back and forth via the cam groove 15b, the roller 17, and the guide pin 16, thereby performing manual focus adjustment.
[0026]
When the focus adjustment ring 2 is moved in the optical axis X direction, the O-ring 5 rolls with the inner and outer peripheral surfaces that hold the focus adjustment ring 2 when the AF mode or the MF mode is set. It is extremely light because there is no rotation, and the rotation of the focus adjustment ring 2 in the circumferential direction is prevented when the AF mode is set without any slight play due to extremely large frictional force with the inner and outer peripheral surfaces holding it. When the MF mode is set, the distance ring 4 can be driven.
[0027]
Next, FIGS. 3 and 4 show an infinite state of another embodiment in which the present invention is applied to a rear focus lens. FIG. 3 is a cross-sectional view of a main part showing an AF mode setting state. These are principal part sectional drawings which show the MF mode setting state, The same code | symbol is attached | subjected to the part corresponding to FIG.1 and FIG.2, and the description is abbreviate | omitted.
[0028]
In this embodiment, the rear lens group is assigned to the focus lens group 23, and the guide pin 16 implanted in the focus lens frame 23 a is inserted into the straight groove 1 e of the lens barrel fixing portion 1 and the cam cylinder 25 via the roller 17. The cam cylinder 25 is engaged with the cam groove 25 b, and the outer peripheral gear portion 25 a of the cam cylinder 25 meshes with the pinion 11 via the intermediate gear 21. Other configurations are the same as those in FIGS.
[0029]
In the AF mode setting state shown in FIG. 3 in which the focus adjustment ring 2 is moved forward (leftward in the figure) with the above-described configuration, the O-ring 5 is the outer periphery of the lens barrel fixing portion 1 as in the previous embodiment. The connecting gear 8 is held between the surface 1 a and the inner peripheral surface of the first circumferential groove 2 a of the focus adjusting ring 2, so that the coupling gear 8 can be engaged with the drive gear 9.
[0030]
Therefore, the rotation of the AF drive shaft 20 on the camera body side includes the connection shaft 14, the pinion 13, the intermediate gear 12, the connection gear 8, the drive gear 9, the central shaft 10, the pinion 11, the intermediate gear 21, the cam cylinder 25, and the roller 17. The focus lens group 23 is advanced and retracted, and the focus is automatically adjusted.
[0031]
In the MF mode setting state shown in FIG. 4 in which the focus adjustment ring 2 is moved rearward (rightward in the figure) from this state, the O-ring 5 has the outer peripheral surface 4a of the distance ring 4 and the first circle of the focus adjustment ring 2. The connecting gear 8 is held by the inner peripheral surface of the circumferential groove 2 a and the clutch coupling with the driving gear 9 is released.
[0032]
In this state, the rotation of the AF drive shaft 20 on the camera body side is not transmitted to the drive gear 9, and the rotation of the focus adjustment ring 2 is transmitted to the distance ring 4 by the frictional force of the O-ring 5. 10, the cam cylinder 25 is rotated through the pinion 11 and the intermediate gear 21, and the focus lens frame 23a is moved back and forth through the cam groove 25b, the roller 17, and the guide pin 16, thereby performing manual focus adjustment.
[0033]
【The invention's effect】
As described above, according to the present invention, the rotation of the focus adjustment ring can be prevented via the O-ring when the AF mode is set, and any focus adjustment ring can be set when the MF mode is set. Manual focus adjustment is possible without any play at the rotational angular position.
[0034]
Since the O-ring, the focus adjustment ring, and the distance ring are firmly friction-coupled over the entire circumference, even if the frictional force with the O-ring is slightly reduced due to aging, the focus adjustment ring and the distance ring There is no risk of circumferential slippage with the ring, and a reliable manual focusing function can be maintained over a long period of time.
[0035]
In the above apparatus, the lens barrel fixing portion and the distance ring are provided adjacent to each other and have the same outer diameter, so that the AF and MF mode can be switched by a slight movement of the focus adjustment ring in the optical axis X direction. Therefore, the operability at the time of switching can be improved.
[0036]
Further, in the above apparatus, if the focus lens group is a middle group lens, the center of gravity of the lens is reduced by focus adjustment and stability is improved, and if the focus lens group is a rear group lens, the focus lens group is Driving from the camera body can be facilitated by approaching the AF driving mechanism on the camera body side.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an AF mode setting state according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the MF mode setting state.
FIG. 3 is a cross-sectional view of a main part showing an AF mode setting state according to another embodiment of the present invention.
FIG. 4 is a cross-sectional view of an essential part showing the MF mode setting state.
[Explanation of symbols]
1: Lens barrel fixing part 2: Focus adjustment ring 3, 23: Focus lens group 4: Distance ring 5: O ring 6: Switching lever 7: Spring 8: Connection gear 9: Drive gear 10: Center shafts 11, 13: Pinion 12, 21: Intermediate gear 14: Connection shaft 15, 25: Cam barrel 16: Guide pin 17: Roller 18: Click ball 19: Leaf spring 20: AF drive shaft (camera body side)

Claims (4)

A focus adjustment ring that can rotate around the optical axis and slide in the direction of the optical axis, and a focus adjustment ring that can be engaged with and disengaged from the focus adjustment ring. A focus adjustment mode of a camera lens having a distance ring capable of driving the lens group in the optical axis direction and switching between the automatic focus adjustment mode and the manual focus adjustment mode by moving the focus adjustment ring in the optical axis direction In the switching device,
When the automatic focus adjustment mode is set, it is held between the focus adjustment ring and the lens barrel fixing portion. When the manual focus adjustment mode is set, the focus adjustment ring rolls from the lens barrel fixing portion to the distance ring. And a focus adjustment mode switching device for a camera lens, wherein an O-ring held between the distance ring and the distance ring is provided. 2. The focus adjustment mode switching device for a camera lens according to claim 1, wherein the lens barrel fixing portion and the distance ring are adjacent to each other and have the same outer diameter. 3. The focus adjustment mode switching device for a camera lens according to claim 1, wherein the focus lens group is a middle lens group. 3. The focus adjustment mode switching device for a camera lens according to claim 1, wherein the focus lens group is a rear group lens.

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