JP3548274B2 - Electric zoom lens barrel - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an electric zoom lens barrel having a zoom operation ring that can be rotated around the optical axis of a taking lens.
[0002]
[Prior art and its problems]
When the zoom ring located at the neutral position in the free state is manually rotated around the optical axis in one direction (forward direction), zooming is performed toward the telephoto side, and when rotated in the other direction (reverse direction), the zoom side is wide-angle side. 2. Description of the Related Art An electric zoom lens barrel that zooms toward a camera is known. This electric zoom lens barrel has a structure in which the zooming speed increases stepwise as the amount of rotation (rotation angle) from the neutral position of the zoom operation ring increases.
[0003]
In this electric zoom lens barrel, for example, in an electric zoom lens barrel having a structure in which the zooming speed is increased stepwise in the order of low speed, medium speed, and high speed, the medium zooming speed is most frequently used. However, in this electric zoom lens barrel, it is surprisingly difficult to instantaneously select a medium zooming speed between a low speed and a high speed by rotating the zoom operation ring by a predetermined amount of rotation. When rotating the zoom operation ring for the purpose of selection, the amount of rotation is often too large to select at a high zooming speed.
[0004]
If you don't want to miss a photo opportunity at a certain moment, the power to operate the zoom control ring is too strong. For this reason, even if an attempt is made to obtain a desired angle at a medium zooming speed, the zoom operation ring is rotated as much as possible, thereby zooming at a high zooming speed to the wide-angle end or the telephoto end at a stretch. In some cases or missed a photo opportunity.
[0005]
[Object of the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an easy-to-operate electric zoom lens barrel having a structure in which a desired zooming speed can be easily selected.
[0006]
Summary of the Invention
According to the present invention, in the conventional electric zoom lens barrel, the rotation torque required for rotating the zoom operation ring selects a high-speed (fastest) zooming speed from a neutral position (zooming stop position) of the zoom operation ring. The focus is on the fact that it is difficult to instantaneously select a medium zooming speed between a low speed and a high speed because the zooming speed is substantially flat over the entire region up to the turning position.
[0007]
The present invention focused on this conventional problem has a zoom operation ring that can be rotated around the optical axis, and changes the zooming speed according to the amount of rotation from the neutral position of the zoom operation ring. The electric zoom lens barrel further includes a rotation torque varying unit that changes a rotation torque required for the rotation operation of the zoom operation ring in a stepwise manner according to a rotation amount from a neutral position of the zoom operation ring. A zooming speed switching plate that rotates with the zoom operation ring; and is fixed to the camera body to engage with engagement projections formed on the zooming speed switching plate from both ends in the circumferential direction. A pair of first moving pieces guided movably in the circumferential direction by a guide member integral with the mount ring to be mounted; a pair of first moving pieces stretched between the pair of first moving pieces, and the pair of first moving pieces approach each other. A first tension spring that moves and urges in a direction to move; a pair of second moving pieces that are located outside the pair of first moving pieces in the circumferential direction and that are guided by the guide member so as to be movable in the circumferential direction; A second tension spring that is stretched between the pair of second movements and urges the pair of second moving pieces to move in a direction approaching each other; When the first moving piece is rotated to After moving against the spring, it is moved against the second moving piece that abuts the moving piece of the first to the second tension spring It is characterized by:
[0008]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 shows an electric zoom lens barrel 10 to which the present invention is applied. This lens barrel 10 is a four-group type zoom lens barrel having first to fourth lens groups L1, L2, L3, L4.
[0009]
The zoom lens barrel 10 has, at the rear end of the barrel, a mount ring 11 for detachably fixing to a camera body (not shown). A mount ring 12 is fixed to the mount ring 11, a housing 13 is fixed inside the mount ring 12, a fixed cylinder 14 is fixed inside the housing 13, and fixed to a front end of the housing 13. The outer cylinder 15 is fixed. An aperture ring 16 is provided between the mount ring 11 and the mount connecting ring 12 so as to be rotatable around the optical axis O.
[0010]
A zoom drive ring 22 is rotatably fitted on the outer periphery of the fixed cylinder 14. At the front end of the zoom drive ring 22, a helicoid ring 20 whose rotation around the optical axis O is regulated and guided straight ahead is fitted. The decorative frame 17 is fitted to the front end of the helicoid ring 20. The helicoid ring 20 and the decorative frame 17 are screwed together by screwing a male helicoid 20 a formed on the outer periphery of the helicoid ring 20 and a female helicoid 17 a formed on the inner periphery of the decorative frame 17.
[0011]
A focus ring 28 is fitted to the front end of the fixed outer cylinder 15 so as not to move along the optical axis O and to be rotatable around the optical axis O. A distance scale ring 27 is fitted around the fixed outer cylinder 15 and the inner circumference of the focus ring 28 so as to be rotatable integrally with the focus ring 28. A distance scale (not shown) is printed on the outer peripheral surface of the distance scale ring 27. The distance scale is formed by a display window 29 fixed to the fixed outer cylinder 15 and an opening 15 a formed in the fixed outer cylinder 15. Observed through. A projection 17b projecting outward from the rear end of the decorative frame 17 is slidably fitted in a lead groove 27a formed on the inner peripheral surface of the distance scale ring 27.
[0012]
Accordingly, when the focus ring 28 rotates, the distance scale ring 27 rotates integrally with the focus ring 28, and the decorative frame 17 rotates integrally with the focus ring 28 while being movable along the optical axis O. Moves forward and backward along the optical axis O while rotating by the screw action of the female helicoid 17a and the male helicoid 20a. The focus adjustment is performed by moving the decorative frame 17 forward and backward. Further, an AF internal gear (not shown) is formed on the inner peripheral surface of the distance scale ring 27, and the AF internal gear meshes with an AF pinion connected to an AF motor to perform the AF operation. The focus adjustment is performed by rotating the distance scale ring 27 by driving the AF motor.
[0013]
The first lens group L <b> 1 is fixed to a lens support frame 17 c protruding inward on the inner peripheral surface of the front end of the decorative plate 17. The second lens group L2 is fixed to the second lens group frame 18a, the fourth lens group L4 is fixed to the fourth lens group frame 18b, and the second lens group frame 18a and the fourth lens group frame 18b are moved in the first direction. It is fixed to the ring 18. The first moving ring 18 has an arm portion 18d protruding from the outer peripheral surface penetrates a straight guide elongated hole 14a (see FIG. 4) formed in the fixed cylinder 14 and has an inclined portion formed at the tip of the arm portion 18d. The protrusion 18e is slidably fitted in a lead groove 22d (see FIG. 3) formed on the inner peripheral surface of the zoom drive ring 22.
[0014]
The third lens group L3 is fixed to a third lens group support frame 19, and the third lens group support frame 19 is connected to the first movable ring 18 and a second movable ring 21 rotatably fitted around the first movable ring 18. Supported. On the outer peripheral surface of the third lens group support frame 19, as shown in a developed view in FIG. 8, three arm portions 19a protrude in the circumferential direction. The arm 19a penetrates the straight guide groove 18c (see FIG. 6) of the first moving ring 18, and an inclined projection 19b formed at the tip of the arm 19a is formed on the inner peripheral surface of the second moving ring 21. Slidably fitted in the three cam grooves 21a (see FIG. 7).
[0015]
The fixed cylinder 14 is formed with a rectilinear guide slot 14a through which an arm 18d formed in the first moving ring 18 penetrates, and the inner peripheral surface of the fixed cylinder 14 projects from the outer peripheral surface of the second moving ring 21. A cam groove 14b into which the tip of the provided projection 21b is slidably fitted is formed. At the front end of the fixed cylinder 14, three rectilinear guide members 23 are fixed in the circumferential direction. Each rectilinear guide member 23 has a guide projection 23a projecting outward. The guide projection 23a is formed in the helicoid ring 20 through a circumferential hole 22e formed in the zoom drive ring 22. Slidably fitted in the rectilinear guide groove 20e.
[0016]
Further, a pin 22a protrudes near the center of the outer peripheral surface of the zoom drive ring 22 fitted to the fixed cylinder 14, and the tip of the pin 22a is engaged with the focal length scale ring 26. A focal length scale (not shown) is printed on the outer peripheral surface of the focal length scale ring 26, and the focal length scale is observed through the display window 29 and the opening 15b formed in the fixed outer cylinder 15. The zoom drive ring 22 has a large diameter portion on the front end side (the first lens group L1 side), and has three pairs of front and rear guide protrusions 22b and 22c on the outer peripheral surface of the large diameter portion in the circumferential direction ( (See FIG. 3). The helicoid ring 20 is formed with three cam projections 20b having surface cams 20c and 20d of a predetermined shape in the front and rear direction in the circumferential direction. Each cam projection 20b is formed by a pair of corresponding guide projections 22b and 22c. They are slidably fitted between them. The contours of the surface cams 20c and 20d of the cam projection 20b are formed such that the combination of the female helicoid 17a and the male helicoid 20a with the lead corresponds to the movement locus of the first lens unit L1.
[0017]
Three cam grooves 22d are formed at equal intervals on the inner peripheral surface of the small-diameter portion of the zoom drive ring 22, and these cam grooves 22d are formed at the tips of the arms 18d of the first moving ring 18. The inclined projection 18e is slidably fitted. The contour of the cam groove 22d corresponds to the movement locus of the second lens unit L2 and the fourth lens unit L4.
[0018]
A zoom operation ring 25 is rotatably fitted around the outer periphery of the mount connecting ring 12 and the fixed outer cylinder 15, and a rubber ring 25a for preventing operation slip is fitted around the outer periphery of the zoom operation ring 25. . The zoom operation ring 25 can be moved to two positions, an electric zoom position moved forward (left side in FIG. 1) and a manual zoom position moved backward, and is moved to the manual zoom position behind. When this occurs, it is linked with the zoom drive ring 22 by a clutch mechanism (not shown). FIG. 1 shows a state where the zoom operation ring 25 is located at the front electric zoom position.
[0019]
A focal length scale ring 26 is rotatably fitted near the mount 11 inside the fixed outer cylinder 15, and the tip of the pin 22 a engages with the focal length scale ring 26. ing. When the zoom drive ring 22 rotates, the rotation is transmitted to the focal length scale ring 26 via the pin 22a, and the focal length scale ring 26 also rotates.
[0020]
At the front end of the housing 13, a support plate 13a extending outward is formed. A zooming speed selection switch unit 50 and a rotating torque varying unit 30 are provided behind the support plate 13a. The zooming speed selection switch unit 50 includes a zoom code plate 52, a brush 54 that slides on the zoom code plate 52, and the like. The rotation torque varying unit 30 includes a guide member 32, first moving pieces 36a and 36b, The second moving pieces 37a, 37b, First tension spring 37 , Second tension spring 38 Etc.
[0021]
A guide member 32 extending parallel to the outer peripheral surface of the housing 13 is fixed to the rear end of the support plate 13a. More specifically, two guide projections 32a (see FIG. 9) projecting forward from the front end face are formed on the front end face of the guide member 32, and the front end face of each guide projection 32a is formed on the support plate portion 13a. The guide member 32 is fixed to the support plate portion 13a by connecting the recess 13b, which is in contact with the corresponding recess 13b, and the guide protrusion 32a, which is in contact with each other, with the screw 33.
[0022]
A zooming speed switching plate 34 is provided between the support plate 13a and the guide member 32 so as to be slidable in the circumferential direction. The zooming speed switching plate 34 is formed with two guide slots 34a extending in the circumferential direction, and the corresponding guide projections 32a are slidably fitted in the respective guide slots 34a. Therefore, the zooming speed switching plate 34 is movable in the circumferential direction within the length range of the guide slot 34a. The zooming speed switching plate 34 has an engagement gear portion 34b formed on the outer peripheral edge. When the zoom operation ring 25 is located at the front electric zoom position, the internal gear 25b formed along the circumferential direction on the inner peripheral surface of the zoom operation ring 25 is engaged with the engagement gear portion 34b. I do. When the zoom operation ring 25 is located at the rear manual zoom position, the internal gear 25b releases the engagement with the engagement gear portion 34b. Therefore, when the zoom operation ring 25 is rotated when the zoom operation ring 25 is located at the front electric zoom position, the zooming speed switching plate 34 is also rotated through the internal gear 25b and the engagement gear portion 34b. I do.
[0023]
On the outer peripheral surface of the housing 13, a zoom code plate 52 made of a flexible printed circuit board having a predetermined pattern is fixed along the circumferential direction, and on this zoom code plate 52, one end of a zooming speed switching plate 34 Is slidably contacted. The zoom code plate 52 and the brush 54 are each electrically connected to a lens CPU (not shown) for controlling the electric zoom, and this lens CPU is operated in accordance with the contact position of the brush 54 on the zoom code plate 52. Change the zooming speed. More specifically, according to the contact position of the brush 54 on the zoom code plate 52, it is possible to stop zooming and select three zooming speeds: low speed, medium speed, and high speed. In accordance with the contact position of the brush 54 on the zoom code plate 52, a zoom motor (not shown) is driven so as to stop zooming or perform zooming at one of low speed, medium speed, and high speed.
[0024]
A pair of first moving pieces 35 (35a, 35b) and a pair of second moving pieces 36 (36a, 36b) are guided by the guide member 32 so as to be movable in a circumferential direction within a predetermined range. The pair of first moving pieces 35a and 35b are respectively moved within the movable ranges a and b shown in FIG. 10 by known guide means such as a guide rail (not shown) formed on the guide member 32. Guided to possible and hung each other First tension spring 37 Are always urged in the direction toward each other. Similarly to the first moving pieces 35a and 35b, the pair of second moving pieces 36a and 36b are shown in FIG. 10 by a known guide means such as a guide rail (not shown) formed on the guide member 32. The guides are movably guided within the movable ranges c and d, and are hung from each other. Second tension spring 38 Are always urged in the direction toward each other.
[0025]
Between the first moving piece 35a and the first moving piece 35b, Zooming speed switching plate 34 An engagement projection 39 extending in a direction parallel to the optical axis O is fixed to the projection. Therefore, Zooming speed switching plate 34 Is in the neutral position shown in FIGS. 9 and 10 in the free state, and when the zoom operation ring 25 is rotated to one side by the rotation operation, the first moving piece 35a moves to the right side in FIG. , The first moving piece 35b moves to the left in FIG.
[0026]
The end 35c of the first moving piece 35a on the side facing the second moving piece 36a can be engaged with the end 36c of the second moving piece 36a on the side facing the first moving piece 35a. . Therefore, when the first moving piece 35a moves to the second moving piece 36a side (right side in FIG. 10) beyond the circumferential position e, the end 35c abuts on the end 36c and the second moving piece 36a moves in the same direction. Move together. Similarly, an end 35d of the first moving piece 35b on the side facing the second moving piece 36b is engageable with an end 36d of the second moving piece 36b on the side facing the first moving piece 35b. I have. Therefore, when the first moving piece 35b moves to the second moving piece 36b side (left side in FIG. 10) beyond the circumferential position f, the end 35d contacts the end 36d and the second moving piece 36b moves in the same direction. Move together.
[0027]
With the above structure, when the first moving piece 35a is moved in the range from the initial position to the circumferential position e by the rotation operation of the zoom operation ring 25, the first compression spring 37 uses the first compression spring 37 for the zoom operation ring 25. When one rotation torque q (see FIG. 11) is applied to move the first moving piece 35a beyond the circumferential position e, the first moving piece 35a moves the second moving piece 36a in the same direction. A second rotational torque r (see FIG. 11) resulting from the combination of the first compression spring 37 and the second compression spring 38 is applied to the ring 25. Similarly, when the first moving piece 35b is moved in a range from the initial position to the circumferential position f by the rotation operation of the zoom operation ring 25, the first rotation of the zoom operation ring 25 by the first compression spring 37 is performed. When the torque q is applied to move the first moving piece 35b beyond the circumferential position f, the first moving piece 35b moves the second moving piece 36b in the same direction. A second rotational torque r is added by combining the compression spring 37 and the second compression spring 38.
[0028]
Zooming speed switching plate 34 Is in the neutral position, Zooming speed switching plate 34 Is in contact with a land (not shown) on the zoom code plate 52 for stopping the zoom motor. Therefore, Zooming speed switching plate 34 When is located at the neutral position, zooming is not performed.
[0029]
Zooming speed switching plate 34 Is rotated in one direction (right side in FIG. 10) from the neutral position, and when the first moving piece 35a is positioned within the range of movement g in FIG. It contacts on a land (not shown) for low-speed zooming to the side. Therefore, Zooming speed switching plate 34 Is rotated in one direction from the neutral position, and when the first moving piece 35a is positioned within the moving range g, low-speed zooming to the wide-angle side is performed.
[0030]
further Zooming speed switching plate 34 Are rotated in the same direction, and when the first moving piece 35a is located within the moving range i up to the position where the second moving piece 36a is slightly moved to the right side in FIG. Is in contact with a land portion (not shown) for performing medium-speed zooming on the wide angle side on the zoom code plate 52. Therefore, Zooming speed switching plate 34 Is rotated in one direction from the neutral position, and when the first moving piece 35a is positioned within the movement range i, medium-speed zooming to the wide-angle side is performed.
[0031]
further Zooming speed switching plate 34 Are rotated in the same direction, and the first moving piece 35a is located within the moving range m for moving the second moving piece 36a to the moving end k on the right side in FIG. Is in contact with a land portion (not shown) for performing high-speed zooming on the wide angle side on the zoom code plate 52. Therefore, Zooming speed switching plate 34 Is rotated in one direction from the neutral position, and when the first moving piece 35a is positioned within the moving range m, high-speed zooming to the wide-angle side is performed.
[0032]
On the other hand, Zooming speed switching plate 34 When is rotated from the neutral position in the other direction (left side in FIG. 10), zooming to the telephoto side is performed. Zooming speed switching plate 34 Is the same as the zoom operation when is rotated in one direction from the neutral position. That is, Zooming speed switching plate 34 Is rotated in the other direction from the neutral position, and when the first moving piece 35b is positioned within the moving range h in FIG. 10, the brush 54 is used to perform low-speed zooming to the telephoto side on the zoom code plate 52. On a land portion (not shown) of the contact. Therefore, Zooming speed switching plate 34 Is rotated in the other direction from the neutral position, and when the first moving piece 35b is positioned within the moving range h, low-speed zooming to the telephoto side is performed.
[0033]
further Zooming speed switching plate 34 Are rotated in the same direction, and when the first moving piece 35b is located within the range of the moving range j up to the position where the second moving piece 36b is slightly moved to the left side in FIG. Reference numeral 54 contacts a land portion (not shown) for performing medium-speed zooming on the telephoto side on the zoom code plate 52. Therefore, Zooming speed switching plate 34 Is rotated in the other direction from the neutral position, and when the first moving piece 35b is positioned within the movement range j, medium-speed zooming to the telephoto side is performed.
[0034]
further Zooming speed switching plate 34 Are rotated in the same direction, and the first moving piece 35b is positioned within the moving range n for moving the second moving piece 36b to the moving end 1 on the left side of FIG. Is in contact with a land portion (not shown) for high-speed zooming on the telephoto side on the zoom code plate 52. Therefore, Zooming speed switching plate 34 Is rotated in the other direction from the neutral position, and when the first moving piece 35b is positioned within the moving range n, high-speed zooming to the telephoto side is performed.
[0035]
The electric zoom lens barrel 10 having the above configuration and to which the present invention is applied operates as follows. When the photographer manually performs zooming, the zoom operation ring 25 is moved to the mount 11 side. Then, the zoom operation ring 25 is linked with the zoom drive ring 22 by a clutch mechanism (not shown). When the zoom operation ring 25 is rotated from this state, the fourth group lenses L1, L2, L3, L4 are moved toward and away from the first group via this clutch mechanism, and zooming is performed.
[0036]
When the zoom drive ring 22 rotates around the optical axis O, the helicoid ring 20 guided straight by the relationship between the guide protrusion 23a and the straight guide groove 20e becomes a cam protrusion interposed between the guide protrusion 22b and the guide protrusion 22c. By the action of 20b, the surface cams 20c and 20d move straight along the optical axis O in accordance with the profile. Since the projection 17b is engaged with the lead groove 17a, the decorative frame 17 moves together with the helicoid ring 20 along the lead groove 17a. That is, the first lens group moves forward and backward along the optical axis O without rotating.
[0037]
The second lens group L2 and the fourth lens group L4 have a relationship in which the arm portion 18d is engaged with the straight guide elongated hole 14a of the fixed cylinder 14, and the inclined projection 18e is engaged with the cam groove 22d of the zoom drive ring 22. Move along the optical axis O without rotating. The third lens unit L3 moves along the optical axis O together with the first moving ring 18 (the second lens unit L2 and the fourth lens unit L4), and further, the arm 19a guides the first moving ring 18 straight. Since it is guided straight in the groove 18 c, it moves along the optical axis O relatively to the first moving ring 18.
[0038]
Here, when the first moving ring 18 moves along the optical axis O, the second moving ring 21 moves along the optical axis O integrally with the first moving ring 18. 14 and slide around the optical axis O. In the third lens group support frame 19, the arm 19 a passes through the straight guide groove 18 c of the first moving ring 18 and the inclined protrusion 19 b engages with the cam groove 21 a of the second moving ring 21. 21 moves along the optical axis O while rotating, and moves forward and backward along the optical axis O by the rotation of the second moving ring 21. That is, the third lens unit L3 relatively moves toward and away from the second lens unit L2 and the fourth lens unit L4.
[0039]
When the photographer performs electric zooming, first, the zoom operation ring 25 is moved forward. Then, the zoom operation ring 25 is disengaged from the zoom drive ring 22 and the internal gear 25b is engaged with the engagement gear portion 34b of the zooming speed switching plate 34, thereby switching from manual zoom to electric zoom.
[0040]
The graph shown in FIG. 11 shows the relationship between the amount of rotation of the zoom operation ring from the neutral position and the rotation torque required for the rotation operation of the zoom operation ring during electric zoom. The horizontal axis indicates the amount of rotation (stroke) from the neutral position of the zoom operation ring 25 to the telephoto side or the wide angle side, and the vertical axis indicates the rotational torque (load) required for the rotation operation of the zoom operation ring 25. The solid line in the graph indicates the change in the rotational torque of the zoom operation ring 25, and the broken line indicates the change in the rotational torque of the conventional zoom operation ring. Further, v in the graph corresponds to the position where the first moving piece 35 contacts the second moving piece 36, and w corresponds to the movement start point of the second moving piece 36.
[0041]
At the time of the electric zoom, when the zoom operation ring 25 is rotated from the neutral position N to a rotation position s obtained by rotating the zoom operation ring 25 by a predetermined amount in one direction or another direction, First tension spring 37 When the first rotation torque q is applied to the rotation to the movement end t beyond the rotation position s, the zoom operation ring 25 First tension spring 37 When Second tension spring 38 , A second rotational torque r is added. As the transition point from the first rotation torque q to the second rotation torque r, a middle zooming speed slightly before the rotation position u of the zoom operation ring 25 that is increased from the middle speed to the high zooming speed is selected. Corresponding to the rotational position s. Therefore, when rotating the zoom operation ring 25 in one direction or the other direction, the photographer feels resistance at the rotation position s where the medium-speed zooming speed corresponding to the transition point is selected, and reduces the high-speed zooming speed. In order to make a selection, it is necessary to rotate the zoom operation ring 25 with an operation force that is gradually increased from the operation force required to rotate from the neutral position N to the rotation position s. Therefore, according to the electric zoom lens barrel 10 of the present embodiment, the photographer feels resistance at the rotation position s where the medium zooming speed is selected in the rotation operation of the zoom operation ring 25, so When the zoom operation ring is rotated with the intention of selecting the zooming speed, it is possible to prevent the rotation amount from being too large and selecting the zooming speed too fast. A feature of the present invention is that a rotation torque varying means 30 for changing the rotation torque required for rotating the zoom operation ring 25 stepwise according to the rotation of the zoom operation ring 25 is provided.
[0044]
【The invention's effect】
As described above, according to the electric zoom lens barrel of the present invention, the rotation torque variable that changes the rotation torque required for the rotation operation of the zoom operation ring stepwise according to the amount of rotation from the neutral position of the zoom operation ring. Since the means is provided, it is possible to provide an easy-to-operate electric zoom lens barrel having a structure in which a desired zooming speed can be easily selected.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an upper half from an optical axis of an electric zoom lens barrel to which the present invention is applied.
FIG. 2 is a development view of a helicoid ring.
FIG. 3 is a development view of a zoom drive ring.
FIG. 4 is a development view of a fixed ring.
FIG. 5 is a front view showing a linear guide member fixed to the fixed ring shown in FIG.
FIG. 6 is a development view of a first moving ring.
FIG. 7 is a development view of a second moving ring.
FIG. 8 is a development view of a third lens group support frame.
FIG. 9 is a development view showing a rotating torque varying unit and a zooming speed selection switch unit provided in the electric zoom lens barrel shown in FIG. 1;
FIG. 10 is an enlarged view showing the rotation torque varying means of FIG.
FIG. 11 is a graph showing a relationship between a rotation amount from a neutral position of a zoom operation ring and a rotation torque required for a rotation operation of the zoom operation ring.
[Explanation of symbols]
10. Electric zoom lens barrel
13 Housing
25 Zoom operation ring
30 Rotation torque variable means
32 Guide member
34 Zooming speed switching plate
35a 35b First moving piece
36a 36b 2nd moving piece
37 1st tension spring (First biasing means)
38 Second tension spring (Second biasing means)
50 Zooming speed selection switch
52 Zoom code board
54 brushes

Claims (2)

An electric zoom lens barrel that has a zoom operation ring that can be rotated around the optical axis and changes the zooming speed according to the amount of rotation from the neutral position of the zoom operation ring,
In accordance with the amount of rotation from the neutral position of the zoom operation ring, a rotation torque variable unit that changes stepwise the rotation torque required for the rotation operation of the zoom operation ring,
This rotation torque variable means
A zooming speed switching plate that rotates with the zoom operation ring;
A pair of first moving pieces circumferentially movably guided by a guide member integral with a mount ring fixed to the camera body and engaged with engagement projections formed on the zooming speed switching plate from both ends in the circumferential direction. When;
A first tension spring that is stretched between the pair of first moving pieces and urges the pair of first moving pieces to move toward each other;
A pair of second moving pieces which are located outside the pair of first moving pieces in the circumferential direction and are guided by the guide member so as to be movable in the circumferential direction;
A second tension spring that is stretched between the pair of second movements and biases the pair of second movement pieces to move toward each other;
With
When the zooming speed switching plate is rotated in the forward / reverse direction by the zoom operation ring, the second moving piece abutting on the first moving piece after moving the first moving piece against the first tension spring. Characterized in that the zoom lens is moved against a second tension spring . 2. The electric zoom lens barrel according to claim 1, wherein the zooming speed is at least a first zooming speed and a second zooming speed higher than the first zooming speed as the rotation amount of the zoom operation ring from the neutral position increases. , The speed is increased step by step,
The zooming speed switching plate of the rotation torque varying means is an electric zoom lens barrel for bringing the first moving piece into contact with the second moving piece just before the speed is increased from the first zooming speed to the second zooming speed. .

Images