JPH10148747A - Driving mechanism of camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving mechanism of camera capable of moving a moving member efficiently and stably. SOLUTION: This moving mechanism comprises a lead screw 11 rotatably driven by a driving source which has a thread part consisting of ridge parts and root parts treated to be smoothed, a moving member being engaged with the thread part of the led screw 11 and moving in the direction of the shaft by rotation of this lead screw, and a helical spring 14 arranged along an outer circumference of the thread part of the lead screw 11 and energizing the moving member in the direction of the shat. And, a winding direction of the helical spring 14 is arranged so as to be in the opposite direction to the direction of the threading of the lead screw 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera driving mechanism, and more particularly, to a camera driving mechanism for moving a moving member by a lead screw.

[0002]

2. Description of the Related Art Various types of camera driving mechanisms applied to cameras such as still cameras and video cameras have heretofore been proposed. Such a driving mechanism uses, for example, a lead screw to move a moving member. There is something to make.

As an example of such a device, Japanese Patent Application Laid-Open No. 3-271728 discloses a method for measuring the distance to a subject, outputting distance information when a distance can be measured, and outputting a distance information when a distance cannot be measured. A distance measuring device that outputs default information, a lens driving device that moves the photographing lens to a plurality of focus positions including a finite farthest focus position, and a long distance mode and an infinity mode based on the input of the default information for a predetermined time A display control device for displaying at intervals, first means for activating the distance measuring device, and release means for outputting second information for selecting the mode while the first information is being output And when the display control device is displaying the long distance mode while the first information is being output by the release means, the second information is output. When the display control device displays the infinity mode, the photographic lens is moved to the infinity focus position when the second information is detected while the display control device is displaying the infinity mode. Thus, an autofocus camera provided with a control means for controlling the lens driving device is described.

In this autofocus camera, a lead screw is used for a mechanism constituting the lens driving device,
Further, a linear guide shaft is provided in parallel with the lead screw, and a coil spring is disposed on the outer periphery of the linear guide shaft to urge the spring in the optical axis direction. I try to eliminate backlash.

Further, Japanese Utility Model Laid-Open No. 4-50810 discloses that
A positioning axis for positioning the lens or the lens frame, and a driving device for driving the lens or the lens frame,
A lens driving device including a moving piece for transmitting the driving force of the driving device to the lens or the lens frame and an elastic body for pressing the lens or the lens frame against the moving piece is described.

[0006] Then, as the driving device, a driving shaft formed separately from the positioning shaft is used. At this time, a lead screw is used as the driving shaft,
It is described that a coil spring disposed on the outer periphery of the lead screw is used as an elastic body.

According to such a configuration, it is described that assembling accuracy of the positioning shaft can be easily obtained, and the lens driving device can be easily and accurately assembled at low cost.

[0008]

However, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 3-271728, the coil spring for urging the lens frame in the optical axis direction is a linear member which is a separate member from the lead screw. Since the lens frame is provided on the outer circumference of the guide shaft, when the lens frame is moved in the optical axis direction by the lead screw, the load of the moment of the coil spring is applied to the lead screw, and the lead screw is driven. The thrust required for this increases by the moment load.

As a means for increasing the thrust required to drive the lead screw, it is conceivable to increase the output by increasing the drive source. In this case, however, the lens frame becomes large in design. At the same time, the power supplied to the drive source increases and the energy consumption increases.

As another means for increasing the thrust required to drive the lead screw, a means for further reducing the driving force from the driving source by a reduction mechanism can be considered. The time required increases. Furthermore, since the number of gears constituting the reduction gear train is increased and the diameter of the gears is increased, the space in the lens frame is reduced, the degree of freedom in design is reduced, and the number of parts is increased. It leads to cost increase.

If the lens frame is driven in a state in which a moment due to a spring force is applied, the stability of the straight driving is impaired, and the accuracy of the stop position at the time of stopping may be reduced.

[0012] Further, in the structure disclosed in Japanese Utility Model Laid-Open No. 4-50810, how the lead screw is inserted into the coil spring is not specified, and therefore, as shown in FIG. When the winding direction of the coil spring 62 and the thread cutting direction of the lead screw 61 are the same, when the coil spring 62 is in a compressed state, as shown in FIG. Will be fitted into the threaded portion as shown by the symbol K. In this case, the coil spring 62 is twisted, rubbed due to contact with the threaded portion of the lead screw 61 to generate abnormal noise, driving unevenness occurs, and the stability of the straight driving is reduced. , The stop accuracy when stopping was reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a camera driving mechanism capable of moving a moving member efficiently and stably.

[0014]

In order to achieve the above object, a drive mechanism for a camera according to a first aspect of the present invention has a lead portion having a screw portion having a peak portion and a valley portion and being rotationally driven by a drive source. A screw, and a moving member that is screwed or engaged with the screw portion of the lead screw and moves along the axial direction of the lead screw by rotation of the lead screw,
A coil spring disposed along the outer circumference of the threaded portion of the lead screw and biasing the moving member in the axial direction of the lead screw, wherein the coil spring has a winding direction of the lead screw. It is arranged so as to be in the opposite direction to the thread cutting direction.

A camera driving mechanism according to a second aspect of the present invention is the camera driving mechanism according to the first aspect, wherein
The surface of the thread portion of the lead screw and / or the surface of the coil spring has been lubricated.

Further, a driving mechanism for a camera according to a third aspect of the present invention includes a lead screw which is rotationally driven by a driving source, and which is screwed or engaged with a screw portion of the lead screw and which is rotated by rotation of the lead screw. A moving member movable in the axial direction, a rotation restricting means for restricting the rotation of the moving member and enabling straight traveling, and an urging means for urging the moving member in the axial direction of the lead screw, The urging means is a coil spring disposed along the outer periphery of a threaded portion of the lead screw,
The winding direction of the coil spring is opposite to the thread cutting direction of the lead screw.

Therefore, in the camera driving mechanism according to the first aspect of the present invention, the lead screw having the screw portion having the crest and the valley is rotationally driven by the drive source, and is screwed or engaged with the screw portion of the lead screw. The moving member moves along the axial direction of the lead screw due to the rotation of the lead screw, and a coil spring disposed along the outer periphery of the thread portion of the lead screw causes the moving member to move the moving member along the axis of the lead screw. And the coil spring is
The coil spring is arranged so that the winding direction is opposite to the thread cutting direction of the lead screw.

Further, in the camera driving mechanism according to the second aspect of the present invention, the surface of the threaded portion of the lead screw and / or the surface of the coil spring is lubricated.

Further, in the camera driving mechanism according to the third aspect of the present invention, the lead screw is rotationally driven by a driving source.
The moving member screwed or engaged with the screw portion of the lead screw moves along the axial direction of the lead screw by the rotation of the lead screw, and the rotation restricting means restricts the rotation of the moving member and can go straight. And, urging means urges the moving member in the axial direction of the lead screw,
The biasing means is a coil spring disposed along the outer circumference of the threaded portion of the lead screw, and the winding direction of the coil spring is opposite to the thread cutting direction of the lead screw.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention. FIG. 1 is a front view showing a lens driving mechanism, FIG. 2 is a side view showing a lens driving mechanism at a reset position, and FIG. FIG. 4 is a side view showing the lens driving mechanism moved from the reset position. FIGS. 4A and 4B show the case where the coil spring disposed on the outer periphery of the lead screw is at (A) a natural length and when the coil spring is compressed, respectively. Sectional view shown,
FIG. 5 is an enlarged side view showing (A) the coil spring when it is at its natural length and (B) when it is compressed.

In the first embodiment, the camera driving mechanism of the present invention is applied to a lens driving mechanism for driving a lens.

A drive source 5 is fixed to the camera body 4, and a front plate 3 is fixed to the front end side thereof with screws or the like.

A photo interrupter gear (hereinafter referred to as a PI gear) 9 is provided between the camera body 4 and the front plate 3.
, The transmission gear 7, the lead screw 11, and the shaft 12 serving as a rotation restricting means are arranged such that their axes are parallel to the optical axis direction.

That is, a plurality of holes are formed in the camera body 4 and the front plate 3 in a direction parallel to the optical axis direction so that the PI gear 9, the transmission gear 7, and the lead screw 11 can be rotated. And the shaft 12 is fixedly held.

Further, a photo interrupter 10 for detecting the rotation of the PI gear 9 is fixed between the camera body 4 and the front plate 3.

The lead screw 11 is formed of an M-thread-shaped shaft member in which a thread portion having a fixed lead (see FIG. 9A) and a ridge portion and a valley portion is engraved on the peripheral surface.
The surface of the thread is lubricated. A screw gear 8 is press-fitted and fixed to the tip of the lead screw 11 and is integrally rotatable with the lead screw 11.

The drive source 5 is, for example, an electromagnetic motor, and a pinion gear 6 is press-fitted at the end of an output shaft thereof to be integrally rotatable. This pinion gear 6 has 2
The transmission gear 7, which is a stepped gear, meshes with a large diameter gear of the transmission gear 7, and the small diameter gear of the transmission gear 7 meshes with the screw gear 8.

Thus, the rotational force output from the drive source 5 is sequentially transmitted via the pinion gear 6, the transmission gear 7, and the screw gear 8 to rotate the lead screw 11.

On the other hand, the pinion gear 6 is
The gear 9 is also meshed, and the PI gear 9 is also rotated by the torque of the drive source 5.

The PI gear 9 has a gear portion that meshes with the pinion gear 6 and has a light-shielding blade that is integrally rotated with the gear portion.
It is a disk member in which a plurality of radial slits are formed in an equiangular width. When the PI gear 9 is rotated by the driving force transmitted from the driving source 5, the PI gear 9 repeats blocking and transmitting the light of the photo interrupter 10, so that a pulse signal is generated from the photo interrupter 10. You.

The moving frame 1 serving as a moving member is a frame member for holding the lens 2 and has a hole formed therein, through which the shaft 12 is slidably inserted. 12 movably in the direction of the optical axis, and its rotation about the optical axis is restricted.

A nut 13 for screwing with the lead screw 11 is fixed to the moving frame 1 so that when the lead screw 11 rotates, the moving frame 1 is moved in the optical axis direction. Has become.

A coil spring 14 as an urging means is supported on the outer periphery of the lead screw 11, and urges the moving frame 1 in the optical axis direction. This coil spring 14 is shown in FIG.
As shown in (A), the winding direction is arranged so as to be opposite to the direction of the screw engraved on the peripheral surface of the lead screw 11, thereby constituting a spring position regulating means. I have. It is more preferable that the surface of the coil spring 14 is also lubricated.

The drive source 5 and the photo-interrupter 10 are connected to a control means 15 which controls the C
It has a PU 15a and a drive circuit 15b.

The operation of such a configuration is as follows.

First, the CPU 15a determines the amount of movement of the moving frame 1 by previously determining a target pulse.
Then, the drive source 5 is driven by the drive circuit 15b,
The number of pulses generated from the photo interrupter 10 is determined by the CPU.
15a controls the drive circuit 15b while counting,
When the target number of pulses is reached, the moving frame 1 is stopped.

At this time, since the coil spring 14 is disposed around the lead screw 11 that directly drives the moving frame 1, the rotation of the lead screw 11 causes the moving frame 1 to rotate.
Is generated, the generation of a moment is suppressed even if the coil spring 14 expands and contracts.

4 (A) and an enlarged view of a part H of FIG. 4 (B) from a state where the coil spring 14 has a natural length as shown in FIG. Since the winding direction of the coil spring 14 is opposite to the direction of the threaded portion of the lead screw 11 even when the compressed state as shown in FIG. The spring 11 does not become entangled with the screw portion.

Further, since the lubrication treatment is performed on the surface of the threaded portion of the lead screw 11 and the surface of the coil spring 14, the expansion and contraction of the coil spring 14 around the lead screw 11 is performed more smoothly.

According to the first embodiment, since the generation of the moment by the coil spring is suppressed, the drive source and the speed reduction system can be downsized, and the lens frame can be downsized. Becomes possible. In addition, the power to be supplied to the drive source can be reduced, and energy can be saved.

Also, since the winding direction of the coil spring is opposite to the direction of the thread portion engraved on the peripheral surface of the lead screw, the coil spring does not become entangled with the lead screw and the moving frame is driven. In addition, it is possible to prevent the generation of abnormal noise at the time of stopping, increase the straight running stability, and improve the accuracy of the stop position when stopping.

Further, since the surface of the thread portion of the lead screw and the surface of the coil spring are lubricated, the coil spring can extend and contract more smoothly on the outer periphery of the lead screw.

Since the lead screw has a constant lead, the target number of pulses can be easily obtained by dividing the moving amount of the moving frame by the moving amount of the lead screw per pulse. And the time required for calculation can be shortened.

6 to 9 show a second embodiment of the present invention. FIG. 6 is a front view showing a lens driving mechanism, FIG. 7 is a side view showing a lens driving mechanism at a reset position, FIG. 8 is a side view showing the lens driving mechanism in the extended position, and FIG. 9 is a diagram showing a case where the moving amount of the moving frame when the lead screw rotates is (A) linear and (B) non-linear. is there. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be mainly described.

In the second embodiment, the shaft 12 of the above-described first embodiment is not provided, and instead, the guide groove 4a serving as rotation restricting means parallel to the optical axis direction is provided in the camera body 4. And a convex part 1a, which is also a rotation restricting means, slidably fitted in the guide groove 4a, protrudes from the outer periphery on the base end side of the movable frame 1. Thereby, the movable frame 1 is guided in the optical axis direction while the rotation around the optical axis is restricted.

The lead screw 11a has a trapezoidal thread, the surface of the thread is lubricated, and the lead is fixed as shown in FIG. 9 (A). It is.

The moving frame 1 is provided with a hole for fitting the outer periphery of the lead screw 11a to move the moving frame 1 in the optical axis direction. A pin 16 for engaging with the trapezoidal thread portion of the screw 11a is fixed.

A coil spring 14 is supported on the outer periphery of the lead screw 11a, and urges the moving frame 1 in the optical axis direction. The coil spring 14 is disposed so that its winding direction is opposite to the direction of the screw engraved on the peripheral surface of the lead screw 11a (see FIG. 5).

In the above description, the leads are fixed. However, in the configuration of the present embodiment, the leads may not be fixed.

That is, as the distance to the subject becomes shorter, the amount of movement of the lens in the direction of the optical axis increases, and the time lag until the lens comes into focus is exponentially greater than when a distant subject is photographed. To increase.

Therefore, it is preferable that the lead of the lead screw 11a is lengthened in the direction in which the moving frame 1 extends to make the change of the lead non-linear.

Thus, when the lead screw 11a rotates, the moving amount of the moving frame 1 in the optical axis direction at that time is as follows.
The result is as shown in FIG. Thus, the time lag does not increase exponentially, but increases linearly.

According to the second embodiment, substantially the same effects as those of the first embodiment can be obtained.
Since the thread portion of the lead screw is formed as a trapezoidal thread, it becomes possible to radially fit the moving frame on the outer periphery of the thread portion, and the shaft used in the first embodiment can be eliminated. As a result, the number of parts is reduced and the cost is reduced.

When the lead of the lead screw is appropriately changed, it is possible to suppress an increase in a time lag at the time of close-up photographing or the like.

FIG. 10 shows a third embodiment of the present invention and is an exploded perspective view showing a lens driving mechanism extended in the optical axis direction. In this third embodiment,
A description of the same parts as those in the first and second embodiments will be omitted, and only different points will be mainly described.

The lens according to the third embodiment is a zoom lens capable of changing the focal length, and is constituted by three lens groups of a first lens group 23, a second lens group 25, and a third lens group 27. Have been.

When changing the focal length,
The distance between the first lens group 23 and the third lens group 27 in the optical axis direction is kept constant.
The magnification is changed by relatively changing the position of the lens group 25. Although a frame member for moving the zoom frame is provided in addition to the zoom frame 21, the description is omitted for simplicity.

The first lens group 23 includes the first lens frame 22
The second lens group 25 includes a second lens frame 24 as a moving member.
Further, the third lens group 27 is held by the third lens frame 26, and these lens frames are disposed on the zoom frame 21 that can be moved in the optical axis direction by a zoom variable operation.

That is, a first lens frame 22 is fixed to the zoom frame 21, and a hole 22a is formed in the first lens frame 22. The tip of the lead screw 28 is formed in the hole 22a. It is fitted rotatably.

On the other hand, the zoom frame 21 is provided with a hole 21a in a convex portion projecting from the inner diameter side, and the rear end of the lead screw 28 is rotatably fitted in the hole 21a. . Thus, the lead screw 28 is disposed parallel to the optical axis.

The lead screw 28 is a shaft-like member having a threaded portion formed by threading an M thread having a fixed lead (see FIG. 9A), and the surface of the threaded portion is subjected to a lubrication treatment. Have been.

The screw portion of the lead screw 28 is screwed into the nut portion 24a of the second lens frame 24. The outer periphery of the lead screw 28 between the second lens frame 24 and the zoom frame 21 has Coil spring 37 as urging means
Is supported so that its winding direction is opposite to the direction of the screw engraved on the peripheral surface of the lead screw 28 (FIG. 5).
), The second lens frame 24 is constantly biased toward the first lens frame 22 side. The surface of the coil spring 37 is also lubricated.

Further, the first lead screw 28
The screw gear 3 to which the driving force is transmitted is provided on the lens frame 22 side.
4, and a light-shielding blade 35b, which is a disk member having a plurality of radial slits formed in an equiangular width, is fixed integrally with the rotation.

The first lens frame 22 has a plurality of shafts 29.
A ground plate 29 having a, 29b, 29c, a hole 29d, and a plurality of screw holes 29e is fastened to the base plate 29. A pinion gear 30a and a light-shielding blade 35a are integrally fixed to the output shaft on the output shaft. Drive source 30 and this drive source 3
A transmission means 31 composed of a gear train for transmitting a zero force to the screw gear 34 of the lead screw 28, and a photo interrupter 36b for detecting the rotation state of the light shielding blade 35b.
And a photo-interrupter 36a for detecting the rotation state of the light-shielding blade 35a are attached.

Here, the drive source 30 is connected to the hole 29d.
Is attached by inserting a screw or the like into a screw hole 29e.

The transmission means 31 meshes with the pinion gear 30a and is rotatably mounted on the shaft 29c.
7, a two-stage gear 46 rotatably attached to the shaft 29b, and a two-stage gear 46 meshing with the small-diameter gear of the two-stage gear 46.
9a and a two-stage gear 45 rotatably attached to the gear 9a to form a reduction gear train. And 2 in the last stage
The small-diameter gear of the step gear 45 meshes with the screw gear 34 to rotate the lead screw 28.

When the driving source 30 rotates, the light-shielding blades 35a and 35b rotate to rotate the photo interrupter 36.
The action of blocking and transmitting the light of a and 36b is repeated. As a result, pulse signals are generated from the photo interrupters 36a and 36b, and the pulse signals are input to the CPU 33a of the control means 33, and the rotation amount of the drive source 30 is detected. Based on the detection result, the CPU 33a drives the driving circuit 33 provided in the control means 33.
The drive control of the drive source 30 is performed via b.

A shaft 39 serving as a guide member and a shaft 40 serving as rotation restricting means are fixed to the second lens frame 24 in parallel with the optical axis, and one shaft 39 is a sleeve serving as a guide member for the third lens frame 26. The other shaft 40 is fitted into a rotation stopper 26a, which is a rotation restricting means of the third lens frame 26.

On the optical axis front side of the third lens frame 26,
The shafts 41 and 42 and the sleeve 44 are fixed in parallel with the optical axis, and the rotation stopper 26a for restricting the rotation of the second lens frame 24 is protruded.

The shaft 41 is fitted in a sleeve 43 fixed to the convex portion 21c on the inner diameter side of the zoom frame 21 so as to be parallel to the optical axis. The third lens frame 26 is movable in the optical axis direction.

Further, a coil spring 38 is supported on the outer periphery of the shaft 41, and urges the third lens frame 26 in the optical axis direction so that the zoom frame 21 and the third lens frame 26 are urged.
Is kept constant.

As described above, since the first lens frame 22 is fixed to the zoom frame 21, the distance between the first lens group 23 and the third lens group 27 is kept constant.

The shaft 42 is fitted in a U-shaped rotation stopper 21 b protruding in the inner diameter direction of the zoom frame 21, and the third lens frame 26 moves in the optical axis direction along the shaft 42. When moving, it restricts rotation around the optical axis.

The amount of movement of the second lens group 25 is
When 1 does not move in the optical axis direction due to zooming, it is used as a focus adjustment amount, and when the zoom frame 21 moves in the optical axis direction due to zooming, it is used as a zoom adjustment amount.

The amount of movement of the second lens group 25 is determined by the CPU.
33a is determined by a predetermined target pulse,
First, by driving the drive source 30 by the drive circuit 33b in the control circuit, the lead screw 28 is rotated via the transmission means 31, and the second lens frame 24 is moved in the optical axis direction.

At this time, the photo interrupters 36a, 36
CPU 3 in the control means 33
3a controls the drive circuit 33b while counting, and stops the second lens frame 24 when the target pulse number is reached.

At this time, since the coil spring 37 directly biases the lead screw 28 for driving the second lens frame 24, generation of a moment is suppressed.

In the above description, the leads are fixed, but in the configuration of the present embodiment, the leads may be made not constant.

That is, as the subject distance becomes shorter, the amount of movement of the lens in the direction of the optical axis increases, and the time lag before focusing on the subject becomes exponential compared to when a subject at a long distance is photographed. To increase. Further, the amount of movement of the lens differs between the wide position and the tele position.

Therefore, by increasing the lead of the lead screw 28 in the portion where the amount of lens movement is large,
It is preferable to change the amount of movement of the movable lens group with respect to the amount of rotation of the same lead screw 28 (see FIG. 9B).

As a result, the time lag does not increase exponentially, but increases linearly.

According to the third embodiment, since the generation of the moment by the coil spring is suppressed, the drive source and the transmission means can be downsized, and the lens frame can be downsized. Becomes possible. In addition, the power to be supplied to the drive source can be reduced, and energy can be saved.

Further, since the winding direction of the coil spring is opposite to the direction of the thread portion engraved on the peripheral surface of the lead screw, the coil spring does not become entangled with the lead screw and the moving frame is driven. In addition, it is possible to prevent the generation of abnormal noise at the time of stopping, increase the straight running stability, and improve the accuracy of the stop position when stopping.

Further, since the surface of the thread portion of the lead screw and the surface of the coil spring are lubricated, the coil spring can extend and contract more smoothly on the outer periphery of the lead screw.

Since the lead of the lead screw is fixed, the target number of pulses can be easily obtained by dividing the moving amount of the moving frame by the moving amount of the lead screw per pulse. This burden is reduced, and the time required for the calculation can be reduced.

On the other hand, when the lead of the lead screw is appropriately changed, an increase in time lag at the time of zooming, close-up photographing, or the like can be suppressed.

In the above description, the control means 33 detects the amount of rotation of the drive source 30 so that the photo interrupter 36
a, 36b and light shielding blades 35a, 35b,
It is also possible to configure without using these.

FIGS. 11 and 12 show a fourth embodiment of the present invention. FIG. 11 is an exploded perspective view showing a lens driving mechanism, and FIG. 12 is a partially enlarged sectional view showing the vicinity of a lead screw. . In the fourth embodiment, the same components as those in the above-described third embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be mainly described.

The first lens frame 22 has a hole 22 as a fixing means.
b, and a lead screw 28 made of a trapezoidal screw having a fixed lead (see FIG. 9A) is provided in the hole 22b.
The distal end of a is fitted with rotation restricted.

On the other hand, the zoom frame 21 is provided with a hole 21d serving as a fixing means at a convex portion protruding from the inner diameter side, and the rotation of the rear end of the lead screw 28a is also restricted by the hole 21d. It is inserted in a state.

A hole 24b is formed in the second lens frame 24. As shown in FIG.
A screw gear 48 as a feed member is rotatably fitted. The screw gear 48 is a substantially cylindrical member in which a gear is engraved on the outer peripheral surface and a screw is engraved on the inner peripheral surface. The screw of this screw gear 48 is screwed with the screw part of the lead screw 28a. Note that the light shielding blade 35 is not directly attached to the lead screw 28a of this embodiment.

On the outer periphery of the lead screw 28a between the first lens frame 22 and the second lens frame 24, a coil spring 37 is provided. Are supported to be reversed (see FIG. 5), and always bias the second lens frame 24 in the direction of the third lens frame 26. The surface of the threaded portion of the lead screw 28a and the surface of the coil spring 37 are lubricated.

[0093] A ground plate 29 is fastened to the second lens frame 24, and a drive source 30 having a pinion gear 30a and a light-shielding blade 35 fixed to an output shaft integrally with the ground plate 29, The force of the driving source 30 is applied to the screw gear 48.
Transmission means 31a formed of a gear train for transmitting the light to a photo interrupter 36 for detecting the rotation state of the light shielding blade 35.
And are respectively attached. This photo interrupter 36 is connected to the CPU 33a,
The rotation amount of the drive source 30 is detected by 33a.

The base plate 29 is provided with a hole 29f, and the lead screw 28a is provided through the hole 29f.

The transmission means 31a includes a plurality of two-stage gears 45, 46, 47 and the screw gear 48.

The operation of the fourth embodiment is similar to that of the third embodiment.
However, when the drive source 30 rotates, the driving force is transmitted to the final stage screw gear 48 of the transmission means 31a, and the screw gear 48 rotates. As a result, the screw gear 48 moves in the axial direction of the lead screw 28a. At this time, since the second lens frame 24 is urged in the optical axis direction by the coil spring 37, it moves in the optical axis direction following the screw gear 48.

According to the fourth embodiment, substantially the same effects as those of the third embodiment can be obtained.

In the above description, the control means 33 detects the amount of rotation of the drive source 30 so that the photo interrupter 36
And the light shielding blades 35 are provided, but it is also possible to configure without using them.

FIG. 13 shows a fifth embodiment of the present invention, and is a cross-sectional view showing a strobe driving mechanism of a camera. In the fifth embodiment, a description of the same parts as those in the above-described first to fourth embodiments will be omitted, and only different points will be mainly described.

In FIG. 13, the solid line indicates a state in which the power of the camera is turned off, that is, a stowed state in which the strobe unit is stored, and the two-dot chain line indicates a state in which the power of the camera is turned on. , That is, the photographing state.

In this embodiment, a camera driving mechanism is applied to a strobe driving mechanism.

A drive source 55 is fixed to the camera body 54. The drive source 55 is driven to rotate in the forward direction when the power of the camera is turned on from off, and is driven to rotate in the reverse direction when the power is turned off from on. .

A pinion gear 55a is fixed to the output shaft of the drive source 55, and meshes with a screw gear 52a which is attached to the lower end of the lead screw 52 so as to rotate integrally therewith.

The lead screw 52 is a trapezoidal screw having a fixed lead (see FIG. 9 (A)).
Is rotatably supported.

A moving member 51 is screwed into the thread portion of the lead screw 52, and a convex portion 51a serving as a rotation restricting means projects from a side portion thereof. This projection 51a
Is engaged with a groove 54a, which is also a rotation restricting means, formed on the camera body 54 so as to be parallel to the axial direction of the lead screw 52, and the rotation of the moving member 51 with respect to the lead screw 52 is stopped. ing.

Further, on the outer periphery of the lead screw 52,
A guide member 53 is slidably fitted, and a lever portion 56b of a strobe light emitting portion 56 of the guide member 53 described later is provided.
The edge on the side where the contact is made is formed as an R surface in order to make the contact smooth.

Further, on the outer periphery of the lead screw 52, a coil spring 57 as an urging means for urging between the guide member 53 and the camera body 54 is engraved on the peripheral surface of the lead screw 52 in the winding direction. It is arranged to be opposite to the direction of the set screw (see FIG. 5). The surface of the coil spring is also lubricated.

The strobe light emitting portion 56 is rotatably supported by the camera main body 54 by a rotating shaft 56a, and a lever portion 56b is sandwiched between the moving member 51 and the guide member 53. As a result, the lever portion 56 b is urged against the moving member 51 via the guide member 53 by the urging force of the coil spring 57.

Next, the operation of such an embodiment will be described.

When the drive source 55 rotates, the lead screw 52 is rotated by the rotational force via the screw gear 52a, and the moving member 51 moves in the axial direction of the lead screw 52.

With the movement of the moving member 51, the lever portion 56b rotates around the rotation shaft 56a, and the strobe light emitting portion 56 is rotated between the housed state and the photographing state.

That is, when the power of the camera is turned on, the moving member 5 in the stored state as shown by the solid line is displayed.
By moving the guide member 53 and the lever portion 56b to a position in a shooting state as shown by a two-dot chain line, the strobe light emitting portion 56 is protruded from the camera main body 54 and becomes in a light emitting state.

Further, even when the coil spring 57 is compressed from the natural length state, the coil spring 57 is disposed so that the winding direction of the coil spring 57 is opposite to the direction of the thread portion of the lead screw 52. In addition, the coil spring 57 does not become entangled with the screw portion.

According to the fifth embodiment, since the winding direction of the coil spring is opposite to the direction of the thread portion engraved on the peripheral surface of the lead screw, the coil spring is attached to the lead screw. There is no entanglement, and generation of abnormal noise when the moving frame is driven can be prevented.

Further, even if the strobe light-emitting unit is protruded from the camera body and is urged toward the stored state by applying some external force, the strobe light-emitting unit is temporarily retracted in the stowed direction. When the external force is removed, the photographing state can be automatically returned again by the urging force of the coil spring.

Further, since the surface of the thread portion of the lead screw and the surface of the coil spring are lubricated, the coil spring can extend and contract more smoothly on the outer periphery of the lead screw.

[Appendix] According to the above-described embodiment of the present invention, the following configuration can be obtained.

(1) A drive source, a lead screw rotated by the drive source, a moving member screwed to the lead screw, and a biasing member for urging the moving member along the axial direction of the lead screw. Force means,
The biasing means is a coil spring disposed along the outer periphery of the lead screw, and a winding direction of the coil spring is opposite to a thread cutting direction of the lead screw. Drive mechanism.

(2) A drive source, a moving member, a lead screw, fixing means for fixing the lead screw, screwed to the lead screw, and contacting the moving member with the lead screw in the axial direction. A feed member that is movable with the moving member along the axial direction by being rotated by the rotary drive source; a guide member that slidably guides the movable member; and a guide member that slides the movable member. Rotation restricting means for restricting rotation so as to be able to move straight along, and urging means for urging the moving member to contact the feed member in the axial direction of the lead screw. The means is a coil spring disposed along the outer circumference of the lead screw, and the winding direction of the coil spring is opposite to the thread cutting direction of the lead screw. A camera driving mechanism.

(3) Driving source, lead screw,
Fixing means for fixing the lead screw, a moving member slidably fitted with the lead screw and slidable along the axial direction, a rotation restricting means for restricting rotation of the moving member, An urging means for urging the moving member in the axial direction of the lead screw, screwing with the lead screw, and abutting on the moving member in the axial direction of the lead screw, and being rotationally driven by the driving source; A feed member movable along the axial direction together with the moving member, wherein the biasing means is a coil spring disposed along the outer periphery of the lead screw, and the coil spring Wherein the winding direction is opposite to the twisting direction of the lead screw.

(4) In additions (1), (2) and (3), the lead of the lead screw is constant.

(5) In additions (1), (2) and (3), the lead of the lead screw is not constant.

(6) In additions (1), (2) and (3), the moving member is a lens frame having a zoom lens group, and is driven by the lead screw to perform a zooming operation.

(7) In additions (1), (2) and (3), the moving member is a lens group constituting a lens frame, and is driven by the lead screw to perform a focusing operation.

(8) A lead screw having a thread portion having a crest portion and a valley portion and being rotationally driven by a drive source, and being screwed or engaged with the thread portion of the lead screw, and rotating the lead screw. A moving member that moves along the axial direction of the lead screw, a coil spring that is disposed along the outer periphery of the threaded portion of the lead screw, and urges the moving member in the axial direction of the lead screw; Spring position regulating means for regulating the radial position of the coil spring with respect to the threaded portion of the lead screw so that the coil spring does not fall into the valley of the threaded portion of the lead screw. Drive mechanism for the camera.

[0126]

As described above, according to the camera driving mechanism of the present invention, the moving member can be moved efficiently and stably.

[Brief description of the drawings]

FIG. 1 is a front view showing a lens driving mechanism according to a first embodiment of the present invention.

FIG. 2 is a side view showing the lens driving mechanism at a reset position in the first embodiment.

FIG. 3 is a side view showing the lens driving mechanism in a state moved from a reset position in the first embodiment.

FIGS. 4A and 4B are cross-sectional views respectively showing (A) a natural length and (B) a compressed state of a coil spring disposed on the outer periphery of a lead screw in the first embodiment.

FIG. 5 is an enlarged side view showing (A) a natural length and (B) a coil spring when compressed in the first embodiment.

FIG. 6 is a front view showing a lens driving mechanism according to a second embodiment of the present invention.

FIG. 7 is a side view showing a lens driving mechanism at a reset position in the second embodiment.

FIG. 8 is a side view showing the lens driving mechanism in the extended position in the second embodiment.

FIG. 9 is a diagram showing a state in which the moving amount of the moving frame when the lead screw is rotated is (A) linear,
(B) Diagram showing the case of non-linearity.

FIG. 10 is an exploded perspective view illustrating a lens driving mechanism according to a third embodiment of the present invention, which is extended in an optical axis direction.

FIG. 11 is an exploded perspective view showing a lens driving mechanism according to a fourth embodiment of the present invention.

FIG. 12 is a partially enlarged cross-sectional view showing the vicinity of a lead screw according to the fourth embodiment.

FIG. 13 is a sectional view showing a strobe drive mechanism of a camera according to a fifth embodiment of the present invention.

FIG. 14 shows a conventional example, where (A) is at a natural length,
(B) The expanded side view which shows each of the coil springs when compressed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Moving frame (moving member) 1a ... Convex part (rotation restricting means) 4a ... Guide groove (rotation restricting means) 5, 30, 55 ... Driving source 11, 11a, 28, 28a, 52 ... Lead screw 12 ... Shaft ( Rotation restricting means) 14, 37, 57: coil springs (biasing means) 21d, 22b: holes (fixing means) 24: second lens frame (moving member) 26a: rotation stopping part (rotation restricting means) 39: shaft ( Guide member) 40 Shaft (rotation restricting means) 44 Sleeve (guide member) 48 Screw gear (feed member) 51 Moving member 51a Protrusion (rotation restricting means) 54a Groove (rotation restricting means)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuya Suzuki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd.

Claims (3)

[Claims] A lead screw rotatably driven by a drive source; and a lead screw screwed or engaged with the screw portion of the lead screw. A moving member that moves along the axial direction of the lead screw; and a coil spring that is disposed along the outer periphery of the threaded portion of the lead screw and urges the moving member in the axial direction of the lead screw. A driving mechanism for a camera, wherein the coil spring is disposed such that a winding direction of the coil spring is opposite to a thread cutting direction of the lead screw. 2. The camera driving mechanism according to claim 1, wherein a surface of a thread portion of the lead screw and / or a surface of the coil spring are lubricated. 3. A lead screw which is rotationally driven by a drive source, and a moving member which is screwed or engaged with a screw portion of the lead screw, and is movable along the axial direction of the lead screw by rotation of the lead screw. And a rotation restricting means for restricting rotation of the moving member so as to be able to move straight, and an urging means for urging the moving member in an axial direction of the lead screw, wherein the urging means comprises the lead A driving mechanism for a camera, comprising: a coil spring disposed along an outer periphery of a thread portion of a screw, wherein a winding direction of the coil spring is opposite to a thread cutting direction of the lead screw.