JP2591778Y2 - Backlash removal mechanism for lens barrel - Google Patents

Description

[Detailed description of the invention]

[0001]

TECHNICAL FIELD The present invention relates to a backlash removing mechanism for a lens barrel.

[0002]

2. Description of the Related Art In a lens barrel, for example, a helicoid structure is widely used as a focusing mechanism for moving a focusing lens in an optical axis direction. This helicoid structure is basically configured by providing a male helicoid on one (for example, a fixed ring) of two annular members that rotate relatively, and a female helicoid that is screwed to the male helicoid on the other (for example, a focusing ring). ing. When the focusing ring is rotated with respect to the fixed ring,
The focusing ring moves in the axial direction according to the lead angle of the helicoid, and focusing is performed.

Instead of the helicoid mechanism, a focusing mechanism is also known in which a focusing ring is provided with a lead groove having a specific lead angle, and a fixed ring is provided with a roller which fits into the lead groove. These are the same in that the two annular members that rotate relative to each other are linearly displaced in the axial direction at a specific lead angle with the relative rotation.

In this focusing mechanism, backlash due to clearance existing between helicoids meshing with each other or between a lead groove and a roller is inevitable. This backlash appears as a phenomenon of image skipping in which the focus position changes suddenly in the focusing mechanism. Conventionally, a lubricant such as grease has been interposed in the clearance to reduce the backlash. However, the physical properties of the lubricant, such as viscosity,
It changes greatly with temperature. For this reason, when the operating temperature range is as wide as −30 ° C. to + 50 ° C. as in a surveillance camera, when the temperature is low, the rotational resistance of the focusing ring increases due to the high viscosity, and driving may be difficult. Conversely, when the temperature is high, the lubricant has a low viscosity and flows out, causing the lens to become dirty or causing internal reflection, thereby deteriorating the optical performance in some cases. Attempts have been made to solve the above problems by applying a solid lubricant, for example, a Teflon-based solid lubricant, as a lubricant, but it is difficult to control the applied thickness of the solid lubricant. For this reason, after applying the solid lubricant, measures such as applying lapping to obtain dimensional accuracy or applying the solid lubricant a plurality of times have been taken, but all of these have poor work efficiency and are costly. Moreover, it has been difficult to completely remove the backlash.

There has been known a biasing type in which one annular member is moved and biased in one axial direction so as to prevent backlash. There is a problem that the biasing force changes depending on the direction position. When the urging force changes, the rotation resistance and the like change, and stable operation cannot be obtained.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backlash elimination mechanism of the type which axially moves and urges an annular member. Aim. Another object of the present invention is to provide a backlash removing mechanism that can move and urge the annular member in the axial direction with a sufficient urging force.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a lens barrel in which two relatively rotating annular members are fitted in a linearly displaced relationship in the axial direction at a specific lead angle with the relative rotation. An inclined pressing surface inclined at the same angle as the lead angle; a spring adjuster member fixed to the other annular member at two spaced apart circumferential positions on the other annular member; In addition, an elastic member is provided between the two fixed positions in the circumferential direction and elastically contacts the inclined pressing surface and supports one of the annular members in the axial direction.

According to this mechanism, since the inclined pressing surface is inclined at the same angle as the lead angle, even if the axial position of the annular member changes, the axial biasing force of the elastic member does not change. The elastic member is fixed to the spring adjuster member, and the elastic member is pressed against the annular member by the spring property of the spring adjuster member, so that the annular member can be pressed with a sufficient urging force. .

The two annular members that rotate relative to each other may be either an annular member screwed with a helicoid, or a first annular member having a lead groove and a second annular member having a roller fitted into the lead groove. The spring adjuster member is
In order to adjust the urging force applied to the annular member by the spring adjuster member itself and the elastic member, it is preferable that the fixed position can be adjusted in the axial direction along the peripheral surface of the annular member.

[0010] The inclined pressing surface and the elastic member may be brought into contact with each other through an orthogonal surface which is substantially perpendicular to the inner and outer peripheral surfaces of the annular member. In consideration of the above, it is desirable that both are brought into contact via a tapered surface inclined with respect to a surface orthogonal to the inner and outer peripheral surfaces of the annular member. The inclined pressing surface may be formed directly on the annular member. Alternatively, an inclined pressing surface may be provided on a pressing member that is formed separately from the annular member, and the pressing member and the annular member may be integrated in the axial direction. .

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
In this embodiment, the present invention is applied to a surveillance camera lens. As shown in FIG. 1, the surveillance camera lens includes, in order from the object side, a focusing lens group L1,
This is a four-unit configuration including a variable power lens unit L2, a compensator lens unit L3, and a master lens unit L4. Each lens group L1 to L4 includes a respective lens frame 11, 12, 1
3 and 14 respectively.

The lens frame 11 is fixed to a focusing ring 16 located on the outer periphery of a fixed cylinder 15. A male helicoid 17 and a female helicoid 18 screwed to each other are formed on the fixed cylinder 15 and the focusing ring 16. ing. The lens frames 12 and 13 are linearly guided by the fixed barrel 15 and move in the optical axis direction by rotation of a cam ring 19 rotatably fitted on the inner circumference of the fixed barrel 15. The master lens unit L4 is fixed to the fixed barrel 15. An annular gear 16a is fixed to the outer periphery of the focusing ring 16, and a pinion (not shown) meshes with the annular gear 16a. This pinion is driven by a motor.

The backlash removing mechanism, which is a feature of the present invention, is provided between the focusing ring (annular member) 16 and the fixed cylinder (annular member) 15. 1 to 5
1 shows a first embodiment of the present invention, in which a helicoid 17 (female helicoid 1) is provided at the rear end of the focusing ring 16.
8) The inclined pressing surface 20 inclined at the same angle as the lead angle θ
Are formed. 2 and 3, since the inclination angle θ is small, FIG. 5 shows a schematic diagram in which the inclination angle θ is exaggerated. The inclined pressing surface 20 is also an orthogonal surface orthogonal to the inner and outer peripheral surfaces of the focusing ring 16. The inclined pressing surface 20 is provided only at an angle corresponding to the rotation angle of the focusing ring 16, and is divided into two in the circumferential direction in this embodiment according to the angle. Further, between the adjacent inclined pressing surfaces 20, a regulating protrusion 21 for regulating the rotation range of the focusing ring 16 is provided.

On the other hand, a spring adjuster member 25 extending in the circumferential direction is fixed on the fixed cylinder 15. The spring adjuster member 25 has a pair of circumferential slots 26 for adjusting a fixed position in the circumferential direction, and a spring span section 25S is formed between the pair of circumferential slots 26. I have. When the springy span 25S is pressed in a direction parallel to the optical axis in a state where at least the position of the pair of circumferential slots 26 is fixed, the springy span 25S is pressed. It has elasticity against pressure.
In this embodiment, the circumferential elongated hole 26 is provided with the inclined pressing surface 2.
When the fixing screw 27 is loosened, the position of the spring adjuster member 25 can be adjusted in a direction parallel to the inclined pressing surface 20.

In the middle of the spring span 25S of the adjuster member 25, an elastic member 31 is provided between the pair of circumferential slots 26 and elastically contacts the inclined pressing surfaces 20 by the shaft 30. ing. In this embodiment, a pair of rotation range restricting stopper pins 32 and 33 are implanted so as to be located on the left and right sides of the elastic member 31. The stopper pins 32 and 33 abut on the rotation range restricting projection 21. The stopper pin 32 regulates the position where the focusing ring 16 is most retracted, that is, the infinity photographing position. The position 16 regulates the most forward position, that is, the shortest photographing position. Since the turning angle of the focusing ring 16 from the infinity shooting position to the shortest shooting position is set in advance at the time of designing the lens, the interval between the stopper pins 32 and 33 should be predetermined based on the width of the turning range restricting projection 21. Can be.

The elastic member 31 has a pair of elastic legs 31a symmetrical with respect to the axis 30 toward the inclined pressing surface 20. The pair of elastic legs 31a are in contact with the inclined pressing surface 20 in an elastically deformed state, and as a result, the focusing ring 16 receives a moving urging force in the forward direction in the optical axis O direction.

In the apparatus having the above configuration, the focusing ring 16 is rotated to adjust the focus to infinity while the fixing screw 27 is loosened. When this adjustment is completed, the spring adjuster member 25 is moved in the circumferential direction along the circumferential long hole 26 to bring the stopper pin 32 into contact with the rotation range regulating projection 21 (FIGS. 2 and 3). In this state, the fixing screw 27 is tightened to fix the spring adjuster member 25 on the fixed cylinder 15. In this fixed state, the elastic member 31 on the spring adjuster member 25 pushes the focusing ring 16 forward through the inclined pressing surface 20, and the spring span portion 25S bends, causing the elastic member 31 to move the inclined pressing surface 20. Press Further, in this state, the stopper pins 32 and 33 regulate both rotating ends of the focusing ring 16.

Since the inclined pressing surface 20 forms the same angle θ as the lead angle θ of the helicoid 17 (female helicoid 18), the forward urging force received by the elastic member 31 by the focusing ring 16 is Is constant irrespective of the turning position of. That is, the helicoid 17 and the female helicoid 18 make contact with the same force on the same contact surface among the front and rear surfaces of the mountain. In particular, even when the focusing ring 16 changes the rotating direction, this relationship is maintained, so that the phenomenon of "image jump" in which the focusing state changes rapidly does not occur. Further, the driving force when driving the focusing ring 16 via the annular gear 16a does not change. The spring span portion 25S of the adjuster member 25 is
Even if the biasing force of the elastic member 31 is weakened due to a change over time, the elasticity of the elastic member 31
Is pressed against the inclined pressing surface 20 to maintain the action of removing backlash. That is, the elastic member 31 and the springy span portion 25S act complementarily in the action of urging the focusing ring 16 forward.

Furthermore, according to this embodiment, since the circumferential elongated hole 26 of the spring adjuster member 25 is formed in parallel with the inclined pressing surface 20, the spring adjuster member 25 is formed.
When the turning range of the focusing ring 16 is adjusted by moving the focusing ring 16 in the circumferential direction, the forward biasing force of the focusing ring 16 by the elastic member 31 does not change. FIG. 2 and FIG.
The state which fixed the spring-like adjuster member 25 in a different position is shown. In both figures, the position of the fixing screw 27 does not change, and the spring adjuster member 2 for the fixing screw 27 is not changed.
It can be seen that the position of 5 has changed. FIG. 6 shows a stopper pin 32 implanted on the spring adjuster member 25.
In this embodiment, stopper projections 32A and 33A made of cut-and-raised pieces are formed on the spring adjuster member 25 in place of the steps 33 and 33. According to this embodiment, the same operation and effect as those of the above embodiment can be obtained. Further, the stopper provided on the spring adjuster member 25 may be provided as one. What is necessary is just to design so that the rotation range control protrusion 21 may contact the both surfaces of one stopper in the circumferential direction.

FIGS. 7 and 8 show another embodiment of the present invention. This embodiment is different from the first embodiment in that a circumferential elongated hole 26A formed in a spring adjuster member 25B is provided.
Are directed in the circumferential direction of the fixed cylinder 15 without being parallel to the inclined pressing surface 20, and in that the fixed position of the spring adjuster member 25B in the axial direction (front-back direction) can be adjusted. If the direction of the circumferential elongated hole 26A is not parallel to the inclined pressing surface 20, when the springy adjuster member 25 is moved in the circumferential direction to change its fixed position, the elastic member 31
, The pressing force of the focusing ring 16 forward changes. However, when the inclination angle of the inclined pressing surface 20, that is, the lead angle between the male helicoid 17 and the female helicoid 18 is small, the change in the pressing force is slight. Even if it is directed strictly in the circumferential direction without performing the above, no substantial problem occurs.

Further, by making it possible to adjust the fixed position of the spring adjuster member 25B in the axial direction (front-rear direction), it is possible to adjust the forward biasing force applied to the focusing ring 16 via the spring span 25S. it can. In this embodiment, the eccentric pin 35 is inserted into one circumferential slot 26A.
Eccentric shaft 36 is inserted. The eccentric pin 35 is rotatable and adjustable about a rotation center 37. With this rotation, the eccentric shaft 36 causes the spring adjuster member 25A to move in the axial direction (front-back direction). e is the amount of eccentricity of the eccentric shaft 36 and the rotation center 37, and the spring adjuster member 25A can adjust the front-back position by a maximum of 2e. By adjusting the front and rear positions of the spring adjuster member 25A, the forward biasing force of the focusing ring 16 by the spring span 25S and the elastic member 31 can be adjusted. After adjusting the front position of the spring adjuster member 25A with the eccentric pin 35, the spring adjuster member 25A is fixed on the fixed cylinder 15 by a fixing means different from the eccentric pin 35.

In the above embodiment, the spring adjuster member 2
5 (25B) is provided with a circumferential elongated hole 26 in order to enable adjustment of the circumferential fixed position.
Is not an essential element of the present invention. That is,
Even if the spring adjuster member 25 is provided at a fixed position,
The effect of the springy span portion 25S for urging the focusing ring 16 forward via the elastic member 31 is not lost. Furthermore, in the above embodiment, not only the elastic member 31 but also the stopper pins (projections) 32, 33 (32A, 33A) are supported on the spring-like adjuster member 25, and the adjusting position of the adjuster member 25A in the circumferential direction is adjusted. The turning end of the focusing ring 16 can be restricted at the same time.
However, the stopper pin is also not an essential element in the present invention. The stopper pin may be provided separately from the spring adjuster member 25 (25B).

FIG. 9 shows a focusing mechanism using lead grooves and rollers instead of the male helicoid 17 and the female helicoid 18. That is, a lead groove 40 having a lead angle θ is formed in the focusing ring 16, and a roller 41 that fits in the lead groove 40 is fixed to the fixed cylinder 15 by a shaft 42. Also in this example, as in the above-described embodiments, the spring adjuster member 2 is placed on the fixed cylinder 15.
5 (25B) can be fixed, and the backlash of the focusing ring 16 can be removed.

FIG. 10 shows another example of the shape and structure of the elastic member 31. The elastic member 31 is formed by insert-molding a metal spring material 31B in a synthetic resin body 31H. 11 to 14 show the elastic member 31.
5 shows another example of the shape. FIG. 11 shows a case in which a hollow portion 31b is provided in an elastic leg 31a to increase the elastic force.
FIG. 13 shows a U-shaped bent portion 31c provided at the end of an elastic leg 31a to increase the elastic force. FIG. 13 shows a configuration in which an elastic contact portion 31e is formed by only one hollow elastic member 31d. Reference numeral 14 denotes a pair of elastic legs 31a each having an asymmetric shape.

In the above embodiment, the inclined pressing surface 20 is
Although formed at the rear end portion of the focusing ring 16, for example, a groove may be formed in the focusing ring 16 and the inclined pressing surface 20 may be formed on one side of the groove.

[0026]

As described above, according to the present invention, in a lens barrel in which two relatively rotating annular members are fitted in a relation of being linearly displaced in the axial direction at a specific lead angle with the relative rotation, One of the annular members is provided with an inclined pressing surface inclined at the same angle as the lead angle, and the other annular member is provided with an elastic member that contacts and presses the inclined pressing surface. The other annular member is pressed with a constant pressing force that does not change depending on the moving position, and backlash can be eliminated. Since the elastic member is supported between the pair of fixed portions of the spring adjuster member having the spring property, not only the elastic force of the elastic member but also the elastic force of the spring adjuster member causes the inclined pressing surface to be inclined. Pressed, thus pressing the annular member with sufficient biasing force,
Backlash can be reliably removed.

[Brief description of the drawings]

FIG. 1 is a side view showing a cross section of an upper half portion of a lens barrel to which a helicoid backlash removing mechanism of the present invention is applied.

FIG. 2 is a development view viewed from an arrow A in FIG.

FIG. 3 is a development view viewed from an arrow A in FIG. 1, showing a state different from FIG. 2;

FIG. 4 is a sectional view taken along line BB of FIG. 2;

FIG. 5 is a development view exaggeratingly showing the lead angle of the helicoid of the annular member and the moving direction of the spring adjuster member.

FIG. 6 is a sectional view showing another embodiment of the present invention and corresponding to FIG. 4;

FIG. 7 is a development view corresponding to FIG. 2, showing another embodiment of the present invention.

FIG. 8 is a plan view illustrating an adjustable amount of the spring adjuster member of FIG. 7;

FIG. 9 is a development view showing an example of a focusing mechanism using a lead groove and a roller.

FIG. 10 is a plan view and a side view showing another example of the elastic member used in the present invention.

FIG. 11 is a plan view showing still another example of the elastic member used in the present invention.

FIG. 12 is a plan view showing another example of the elastic member used in the present invention.

FIG. 13 is a plan view showing another example of the elastic member used in the present invention.

FIG. 14 is a plan view showing another example of the elastic member used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Lens frame 15 Fixed ring (annular member) 16 Focusing ring (annular member) 17 18 Helicoid θ Lead angle 20 Inclined pressing surface 21 Rotation range restricting projection 25 25B Spring adjuster member 25S Spring span section 26 26A Circumferential slot 27 Fixing screw 31 Elastic member 32 33 Stopper pin (rotation range restricting member) 32A 32B Stopper projection (rotation range restricting member) 40 Lead groove 41 Roller

Claims (4)

(57) [Scope of request for utility model registration] 1. A lens barrel in which two annular members that rotate relative to each other are fitted so as to be linearly displaced in the axial direction at a specific lead angle with the relative rotation. An inclined pressing surface inclined at the same angle is provided. The other annular member is provided with a spring adjuster member fixed to the other annular member at two positions in the circumferential direction that are separated from each other. A lens barrel back, which is located between two fixed positions in the circumferential direction, and supports an elastic member which elastically contacts the inclined pressing surface and urges the one annular member to move in the axial direction. Rush removal mechanism. 2. The backlash removing mechanism for a lens barrel according to claim 1, wherein the two annular members that rotate relative to each other are two annular members that are screwed together with a helicoid. 3. The back of a lens barrel according to claim 1, wherein the two annular members that rotate relatively are a first annular member having a lead groove and a second annular member having a roller fitted in the lead groove. Rush removal mechanism. 4. The backlash removing mechanism for a lens barrel according to claim 1, wherein said spring adjuster member is adjustable in a fixed position in an axial direction along a peripheral surface of said annular member.