JPH07336938A - Device for driving moving member - Google Patents

Abstract

PURPOSE:To maintain a high performance and at the same time freely select material without any need for changing the characteristics of a drive motor. CONSTITUTION:A stepping motor 1 and a transfer shaft 2 where a lead screw groove 3 is formed and which is rotated by the stepping motor l are supported by a support member 4 and are mounted to a body fixing side. A step part 7 is formed on plane 4c for connecting a rear end face 4a and a front end face 4b of the support member 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable member such as a lens group in a lens moving device used in a video camera, a still camera or the like, or a head portion in a magnetic head moving device or an optical head moving device used in a recording device or the like. The present invention relates to a movable member moving device that requires highly accurate movement control, such as a movable member.

[0002]

2. Description of the Related Art Conventionally, a movable member such as a lens group of a lens moving device in an automatic focusing mechanism (autofocus) mechanism and a magnification changing (zooming or zooming) mechanism used in a video camera, a still camera, etc., a recording device, etc. In order to control the movement of a movable member such as a head portion in the magnetic head moving device or the optical head moving device used for, a lead screw groove 13 is formed in the transmission shaft 12 of the drive motor 11 as shown in FIG. Support member 14
There is known a drive mechanism having a configuration in which the drive motor 11 and the transmission shaft 12 are supported by. And
A movable member such as a lens group or a head portion is engaged with the lead screw groove 13 directly or via an engaging member. As an engaging method, there are a method of using a screwing member having a groove that is screwed with the lead screw groove 13 and a method of using a small ball that follows the lead screw groove 13. The operation by this drive mechanism is such that when the drive motor 11 rotates a predetermined angle by a predetermined signal from the drive circuit, the lead screw groove 13 also rotates the same angle and is guided by the thread groove of the lead screw groove 13.
The movable members such as the lens group and the head portion engaged with the lead screw groove 13 linearly move in the axial direction of the lead screw groove 13. The rotary motion of the drive motor 11 is converted into the linear movement of the movable member. As a result, the lens group or the like moves in the optical axis direction, and the head unit or the like moves in the scanning direction or the tracking direction.

By the way, when such a drive mechanism is used, in a lens moving device for a video camera, for example, when a lens group, which is a movable member, moves in the lens barrel for zooming, it is driven during movement. The vibration from the motor affects the movable member, causing image distortion during shooting. Further, in the lens moving device for a still camera, vibration from the drive motor remains as a residual after the stop of the lens group that is the movable member, and if such a residual vibration occurs, the shutter operation is performed immediately after focusing. Therefore, it becomes difficult to obtain a desired photo opportunity. In order to avoid such inconvenience, various methods have been conventionally proposed. Further, such an inconvenience is a problem in that a movable member such as a head portion in a magnetic head moving device or an optical head moving device used in a recording device or the like can obtain an accurate tracking operation and shorten a tracking time. The same applies to the need for countermeasures.

In particular, the movable member and the lead screw groove 13
Although many proposals have been made regarding the engaging portion with the lead screw groove 13, even if the engaging portion between the movable member and the lead screw groove 13 is improved, the following problems occur. That is,
Vibrations at the time of starting, rotating, and stopping the drive motor 11 cause a slight vibration of the entire support member 14, which causes a slight vibration of other members and the entire housing, which adversely affects the movable member. The presence of such slight vibrations is inconvenient because the problems such as the image blurring described above are not improved. In addition, noise may be generated due to the vibration of the entire housing.

Particularly, when a stepping motor, which is often used for the movable member moving device as described above because of easy position control, is used as a drive source, such inconvenience shows a clear tendency. There are many. In order to prevent this, conventionally, adjustments have been made by lowering the torque or drive frequency of the stepping motor or changing the material of the support member 14.

[0006]

However, if the torque of the stepping motor is lowered, it is disadvantageous to the load of the movable member and the rise becomes slow, and if the driving frequency is lowered, the moving speed of the movable member becomes slower. In any case, the response speed and the moving speed are deteriorated and the performance is deteriorated, which is extremely inconvenient. Changing the material of the supporting member is often an inconvenient method because it increases the cost or makes the processing difficult depending on the material, and thus it has a drawback that the selection range is narrow and inconvenient.

The present invention has been made in view of the above points, and an object of the present invention is not to change the characteristics of the drive motor, and the material of the supporting member is not restricted and a wide range of materials can be used. It is to provide a stable movable member moving device that can be selected from among the above, facilitates manufacturing, and reliably prevents vibration and noise.

[0008]

To achieve the above object, a movable member moving device of the present invention comprises a fixed member movably supporting the movable member, a drive motor for moving the movable member, and a lead screw. A transmission shaft provided with a groove and rotated by a drive motor; an engagement portion that engages with the movable member and the transmission shaft to convert the rotation of the transmission shaft into movement of the movable member; and the drive motor and the transmission shaft. And a supporting member attached to the fixing member, and the supporting member is provided with a stepped portion for suppressing vibration. Further, another solving means of the present invention is that the step portion is a plurality of concave portions formed by pressing. Still another solution of the present invention is that the movable member is an optically movable member and the fixed member is a lens barrel member.

[0009]

With the formation of the stepped portion, the resonance frequency of the support member is changed to a predetermined value, it becomes unresponsive to the vibration from the drive motor and the like, and the vibration transmission to other members is prevented. In addition, the formation of the stepped portion increases the mechanical strength of the support member and increases the vibration damping action. By forming the step portion as a plurality of recesses formed by pressing, it is possible to cope with a plurality of resonance frequencies, and thus a plurality of resonance phenomena can be prevented from being suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applied to various movable member moving devices, but as a preferred embodiment, a case of being applied to a lens moving device for a video camera will be described. Therefore, prior to the description of the characteristic portion of the present invention, first, a generally known overall configuration of a lens moving device for a video camera will be described with reference to FIGS.
Will be explained. FIG. 1 is a schematic sectional view of a lens moving device for a video camera, which is schematically shown here. FIG. 2 is a perspective view of a lens moving device for a video camera, and particularly shows the drive mechanism part in a disassembled state.

Reference numeral 101 denotes a lens barrel body, which is a fixed frame 101.
The objective lens 102, which is the first lens group arranged closest to the subject side by a, is fixed by a known method / means. The fixed frame 101b is formed integrally with the lens barrel body 101, and fixes the third group lens 103.
The master flange lens barrel portion 101d is the lens barrel body 1
01 is integrally formed. A guide pole 104 is an auxiliary frame 1 formed integrally with the lens barrel body 101.
01c and the fixed frame 101a, a movable frame 106 holding a variable power lens 105 which is a second group lens is slidably arranged at a guide portion 106a. 107
Is a guide pole, and is a guide frame which is provided between the auxiliary frame 101c integrally formed on the lens barrel body 101 and the fixed frame 101a and which holds the variable magnification lens 105 as the second group lens. It is arranged slidably at 108a and 108b.

Reference numeral 109 is a zoom drive motor. The rotation shaft 110 of the zoom drive motor 109 is the motor case 1
The lead screw groove 112 is formed on the outside of the base 11 by a predetermined length. A shaft member having a lead screw groove may be independently formed so as to be fitted to the rotary shaft. Reference numeral 113 denotes a support member, which supports the zoom drive motor 109 and the rotary shaft 110, and is used for the lens barrel body 1
It is attached to 01. The zoom drive mechanism unit is configured in this way.

Reference numeral 114 denotes a nut body, which has a groove formed therein to be screwed into the lead screw groove 112,
It is guided by sliding at 07. One end of the nut body 114 on the guide pole 107 side is provided with the guide portion 108a of the moving frame 108,
The moving frame 108 and the nut body 114 are sandwiched by 108b.
And can move together. In addition, one end of the nut body 114 on the guide pole 107 side,
A spring spring, a rubber member, or the like may be interposed between the guide portion 108a or 108b to elastically bias them into the engaged state. In any of the configurations, when the zoom drive motor 109 rotates, the moving frame 108 moves in the optical axis direction via the nut body 114, and thus the variable power lens 105, which is the second group lens,
It moves linearly along the optical axis. The nut body 114
The method of engaging the moving frame 108 with the moving frame 108 is not limited to this embodiment. For example, the nut body 114 is not slidably guided by the guide pole 107 but is engaged with the moving frame 108 by an appropriate means. Alternatively, the nut body 114 and the moving frame 108 may be integrally formed. As described above, the nut body 114 is used for the zoom drive motor 10
The rotary motion of the zoom lens 9 is converted into a linear movement of the variable power lens 105 in the optical axis direction.

Reference numeral 115 is a diaphragm blade which performs a predetermined diaphragm operation in response to a signal from a control circuit (not shown).

Reference numeral 116 denotes a guide pole, which is a fixed frame 101b integrally formed with the lens barrel body 101 and an auxiliary frame 10.
The moving frame 118, which is installed between the first lens group 1e and the focus lens 117, which is the fourth lens group, holds the guide portion 118.
It is slidably arranged at a. A guide pole 119 is also provided between the fixed frame 101b integrally formed on the lens barrel body 101 and the auxiliary frame 101e, and the movable frame 120 holding the focus lens 117 as the fourth group lens is a guide part. It is slidably arranged at 120a and 120b.

Reference numeral 121 is a focus drive motor.
The rotation shaft 122 of the focus drive motor 121 is extended outside the motor case 123 by a predetermined length.
A lead screw groove 124 is formed in this extended portion. A shaft member having a lead screw groove may be independently formed to be fitted with the rotary shaft. A support member 125 supports the focus drive motor 121 and the rotary shaft 122, and is attached to the lens barrel body 101. The focus drive mechanism section is configured in this way.

Reference numeral 126 denotes a nut body, which is formed with a groove to be screwed into the lead screw groove 124.
It is slid and guided by 19. One end of the nut body 126 on the guide pole 119 side is provided with the guide portion 120a of the moving frame 120,
The moving frame 120 and the nut body 126 are sandwiched by 120b.
And can move together. In addition, one end of the nut body 126 on the guide pole 117 side,
A spring spring, a rubber member, or the like may be interposed between the guide portion 120a or 120b so as to be elastically biased into an engaged state. In either configuration, when the focus drive motor 121 rotates, the moving frame 120 moves in the optical axis direction via the nut body 126, and thus the focus lens 119, which is the fourth lens group, moves in the optical axis direction. Move linearly to. Note that the engagement between the nut body 126 and the moving frame 120 is not limited to this embodiment, and for example, the nut body 126 is not slidably guided by the guide pole 117, but the moving frame 120 and the moving frame 120 are engaged by an appropriate means. Engage, or nut body 12
6 and the moving frame 120 may be integrally formed. As described above, the nut body 126 acts so as to convert the rotational movement of the focus drive motor 121 into a linear movement of the focus lens 119 in the optical axis direction.

In this embodiment, each lens group is composed of a single lens, but the required lens group may be composed of a plurality of lenses if necessary.

The zoom drive motor 109 is attached to the lens barrel body 101 with the lead screw groove 112 and the nut body 114 engaged.
3 is arranged in the lens barrel main body 101, the hole 113a of the support member 113 is aligned with the screw hole 101f of the lens barrel main body 101, and the fixing is performed with a screw (not shown). Similarly, the focus drive motor 121 is attached to the lens barrel body 101 by the lead screw groove 12
4 with the nut body 126 engaged, the support member 125 is arranged on the lens barrel body 101, and the support member 125
Hole 125a of the lens barrel 101g screw hole 101g
It is performed by fixing with a screw (not shown) according to the above.

In the above-mentioned structure, in photographing, for example, the zoom lens 105, which is the second lens group, is linearly moved in the optical axis direction by the zoom drive motor 109 in accordance with desired zooming. In association with this, the focus lens 117 which is the fourth lens group is linearly moved in the optical axis direction by the focus drive motor 121.
It is normal for a video camera to perform many of these movements during shooting.

Next, the details of the drive mechanism will be described with reference to FIGS. The zoom drive mechanism unit and the focus drive mechanism unit have the same basic configuration, and therefore will be described in common. A stepping motor 1 serves as a drive source for the drive mechanism section. A lead screw groove 3 is formed on a transmission shaft 2 which is an output shaft of the drive source. Reference numeral 4 denotes a support member, which is made of a material such as SUS and has a rear end surface 4a that supports the stepping motor 1, a front end surface 4b that supports the transmission shaft 2, and a flat surface 4c that connects these surfaces. There is. As shown in FIG. 5, the stepping motor 1 and the supporting member 4 are attached to each other by using the mounting holes 4d and the screws 5 and the like, and the supporting member 4 has the holes 4 on the rear end surface 4a.
The bearing 6 of the transmission shaft 2 is fixedly mounted on e. The bearing 6 of the transmission shaft 2 may be fixed to the hole 4e of the rear end surface 4a of the support member 4 by fixing the bearing 6 and the stepping motor 1 to each other. It may be only fitted.

In this embodiment, a stepped portion 7 is formed by a plurality of recesses formed by pressing, and is formed on the surface 4c of the support member 4 parallel to the transmission shaft 2. In this embodiment, the recesses are formed. The side that becomes is the surface on the side where the transmission shaft 2 is arranged. The step portion 7 is thus formed on the surface 4c of the support member 4 in this manner.
By being formed, the resonance frequency of the support member 4 substantially changes to a value different from the resonance frequency value before the step portion 7 is formed. Due to this change, the resonance frequency of the support member 4 and the resonance frequency of the stepping motor 1 are relatively different from each other, and the conventional vibration does not occur. In this embodiment, the concave side is the surface on which the transmission shaft 2 is arranged, and the surface of the surface 4c opposite to the transmission shaft 2 is the convex part. It may be formed so that the side on which 2 is arranged is a convex portion, and it may be formed freely in consideration of space saving and the like. Further, the shapes and sizes of the respective recesses may be different from each other without being the same, and various combinations thereof can be adopted.

Here, the conventional method will be confirmed for the purpose of comparison with the features of the present invention. Conventionally, as a method of preventing and suppressing vibration without using another member such as a vibration absorbing member such as an elastic member, first, making the supporting member heavy can be mentioned. In order to make the support member heavy, there are methods such as increasing the thickness and increasing the volume, and using a material having a high density, but in any case, it is disadvantageous in weight reduction and increases the volume. Is also disadvantageous in terms of space. As the next method, a material having a different hardness is used as a material to be used, and a softer material is generally used. However, it is disadvantageous in terms of strength, and its selection range is small. In addition, there is a method of bending the outer peripheral edge of the support member by, for example, bending to form a rib, but the vibration conditions (area and length) that easily cause resonance do not change, and the vibration of the vibration source is large. Resonance is also likely to occur, and such bending reduces the flatness of the support member, and forming ribs on the outer peripheral edge is disadvantageous in terms of space saving. As described above, these methods provide some degree of anti-vibration action against all vibrations, but the conditions of resonance as a member remain unchanged, and the factors that easily resonate are still retained. It has some disadvantages.

On the other hand, the method of changing the resonance frequency used in the present invention focuses on the vibration of the portion which causes resonance and resonates at the particular frequency, which is a problem, and eliminates the portion of the vibration node. Therefore, a predetermined area or a predetermined length that causes the resonance is appropriately divided to eliminate a portion serving as a node of vibration. As a result, no reaction such as resonance occurs with respect to the specific frequency. Therefore, in the method of the present invention,
Even if the shape and size of the support member are changed, the resonance frequency can be easily changed correspondingly.

When the drive motors are used at two positions, for example, for zooming and for focusing, as in this embodiment, the moving distance of the lens or lens group, which is each movable member, in the lens barrel is different. The drive motor for focusing and the drive motor for focusing have different lengths of the extended transmission shafts. Therefore, according to the present invention, the supporting members may be formed of the same material, and the stepped portions 7 may be formed corresponding to the respective resonance frequencies, although the supporting members are different in length and size. There is an advantage.

Therefore, the shape, size, height and arrangement of the stepped portion 7 are not limited to those shown in FIGS. 3 and 4, and various selections are possible, for example, hexagonal honeycomb shape. It is also good. It is also possible to simply provide one step portion. Further, the formation is not limited to pressing, and may be formation by thinning processing by chemical processing such as grinding / cutting processing, oxidation, and etching.
In any case, the step portion 7, the resonance frequency f ₁ of the support member 4 step portion 7 is formed, an integral multiple of the resonant frequency f _1, and any co the resonance frequency f ₁ irreducible fraction several times However, by making the shape and arrangement so as to be different from the resonance frequency f ₀ of the stepping motor 1, it is possible to completely prevent vibration. Therefore, the vibration is not transmitted to the lens barrel main body side, and does not affect the moving operation of the movable member.

The step portion 7 may be formed by a press.
The greater advantage is that it is very easy to form, the number and arrangement of them can be changed very easily and quickly, the influence on the supporting member that requires a certain rigidity is extremely small, and the shape is appropriate. -There is a point that the rigidity is further improved by making the concave portion of a size.

Further, as in the supporting member 8 shown in FIG. 6, a single stepped portion 8d is formed by half blanking (drawing), and by appropriately setting the shape, size, height and the like. The resonance is reliably eliminated, and the surface accuracy of each surface of the support member and the angular relationship between the surfaces are secured. When forming the stepped portion 8d, which surface of the flat surface 8c on which the convex surface of the stepped portion 8d is to be arranged is a matter that is appropriately determined in consideration of mounting to other components, and for example, can be saved. It is selected due to reasons such as space. In FIG.
A stepping motor portion is attached to the rear end face 8a, and the front end face of the rotating shaft (not shown) is supported by the front end face 8b. Further, 8e is a hole for a member such as a screw for attaching and fixing the support member 8 to the main body side (not shown). It should be noted that the formation of a recessed surface having a large area is performed by, for example, half blanking (drawing) or the like. However, if the area is widened, the force distortion in the stepped portion becomes large and corrosion easily occurs, In that case, it is easy to change the structure by dividing it to form a plurality of step portions, and the degree of freedom in design is great.

Further, in this embodiment, since the step portion 7 has the largest area of the supporting member 4 and is formed on the surface most likely to cause resonance, the mechanical strength of the supporting member 4 is enhanced. Also, the vibration is less affected, and the vibration of the entire structure (assembly) including the drive motor unit and the support member 4 is controlled to provide a vibration damping effect.

Further, since it is only necessary to form such a stepped portion 7, it is possible to use a vacant space between members, save space, and prevent vibration with the same size as the conventional one. Does not become large. In particular, like the lens barrel of the lens moving device including the above-described embodiment, when the drive mechanism section is arranged on the outer peripheral portion of the cylindrical fixing member, there is little unevenness from the viewpoint of space saving. Is desired to
The configuration of the present invention is extremely advantageous in this respect as well.

As described above, the present invention is very effective in preventing image blurring during shooting in a lens moving device for a video camera in which zooming is frequently performed during shooting, but still the lens for still cameras is used. The effect is also extremely large in the moving device, the magnetic head moving device, or the optical head moving device.

[0032]

As described above, by using the movable member moving device of the present invention, the vibration of the drive motor is not transmitted to the support member. Therefore, vibration to the movable member is also prevented, a high quality image can be obtained, and high speed operation is possible. In addition, the mechanical strength is also improved and the overall vibration damping effect is obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view schematically showing a lens moving device for a video camera used as an embodiment of the present invention.

FIG. 2 is a perspective view of a lens moving device for a video camera used as an embodiment of the present invention, particularly showing a state in which a drive mechanism unit is disassembled.

FIG. 3 is a perspective view showing a drive unit according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a drive unit according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a drive unit according to an embodiment of the present invention.

6A and 6B are main parts of another embodiment of the present invention, FIG. 6A is a plan view, and FIG. 6B is a side view with a part omitted.

FIG. 7 is a perspective view showing a drive unit of a conventional example.

[Explanation of symbols]

 1 Stepping motor 2 Transmission shaft 3 Lead screw groove 4 Support member 5 Screw 6 Bearing 7 Stepped portion 8 Support member

Claims (3)

[Claims] 1. A fixed member movably supporting a movable member, a drive motor for moving the movable member, a transmission shaft provided with a lead screw groove and rotated by the drive motor, and the movable member. An engaging portion that engages with the transmission shaft and converts and transmits the rotation of the transmission shaft into movement of the movable member; and a support member that supports the drive motor and the transmission shaft and is attached to the fixed member. A movable member moving device, comprising a stepped portion provided on the support member for suppressing vibration. 2. The movable member moving device according to claim 1, wherein the step portion is composed of a plurality of recesses formed by pressing. 3. The movable member moving device according to claim 1, wherein the movable member is an optically movable member, and the fixed member is a lens barrel member.