JP2005069323A - Feed screw method and feed screw mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feed screw method and a feed screw mechanism capable of realizing a compact apparatus by eliminating biting and tooth skipping of a screw portion with a simple configuration.
By rotating a lead screw 4 on which a screw portion 4a is formed, a moving nut 5 having a female screw portion 5a screwed with the screw portion 4a of the lead screw 4 is moved along the axial direction of the lead screw 4. In the feed screw mechanism using the feed screw method of moving the lead screw 4, the lead screw 4 can be rotated in a state where the moving nut 5 is located in a portion where the screw portion 4 a of the lead screw 4 is not formed.
[Selection] Figure 1

Description

  The present invention relates to a feed screw method and a feed screw mechanism, and in particular, includes a feed member and a phase member, and uses a lead screw as the feed member to convey a moving member along the lead screw. The present invention relates to a feed screw method and a feed screw mechanism in consideration of prevention of biting between the feed screw and the feed member.

  As a conventional feed screw mechanism 102, as shown in FIGS. 5 and 6, for example, a lead screw used for the operation of an optical system of an imaging apparatus 101 such as a video camera and configured integrally with a rotating shaft of a motor 103. 104, a moving nut 105 to be screwed with the threaded portion 104a of the lead screw 104, and a moving frame 108 that is configured integrally with the moving nut 105 and that holds the optical system 107. It is known that the rotational motion is converted into a linear motion by the lead screw 104 and the moving nut 105 to move the moving frame 108 along the axial direction of the lead screw 104. Reference numerals 113 and 114 in the figure are guide shafts for slidably guiding the moving frame 108.

  However, in the above-described prior art, as shown in FIG. 6, when the moving nut 105 moves beyond the moving range due to a control error of the motor 103, the moving nut 105 interferes with the end surface 111 b of the lead screw bearing 111. Since the screw portion 104a of the lead screw 104 and the screw fitting portion 105a of the moving nut 105 are caught, there is a problem that the motor 103 cannot be restored even if it is rotated in the reverse direction.

Therefore, as shown in FIG. 7, for example, a carriage 205 of a type in which a screw fitting portion 205 a screwed to the lead screw 104 is sandwiched between buffer members 205 b and 205 c having spring properties from both sides is provided. This prevents the screw fitting portion 205a from biting in even if it interferes with the end surface 111b of the lead screw bearing 111, or transmits the driving force of the focus mechanism, which is the feed screw mechanism, when the user performs an incorrect operation. There has been proposed a photographing apparatus (see Patent Document 1) that is controlled in advance to prevent malfunction of the apparatus.
JP 2000-180694 A

  However, according to the above-described method, the biting of the screw fitting portion 205a has a problem in that the length of the carriage 205 in the thrust direction increases because the screw fitting portion 205a is sandwiched between the buffer members 205b and 205c. . Further, when an impact is applied to the entire unit, there is a problem that tooth skipping occurs in the screw fitting portion 205a and an error occurs in the control of the motor 103.

  Further, the method described in Patent Document 1 has a problem that the device configuration and control are complicated.

  The present invention has been made in view of the above-described conventional problems, and provides a feed screw method and a feed screw mechanism capable of realizing the downsizing of the apparatus by eliminating the biting and tooth skipping of the screw portion with a simple configuration. It is for the purpose.

  The present invention relates to a feed screw method, and by rotating a lead screw formed with a screw portion, a moving member having a female screw portion screwed with the screw portion of the lead screw is arranged along the axial direction of the lead screw. In the moving feed screw method, the lead screw can be rotated in a state where the moving member is positioned at a portion where the screw portion of the lead screw is not formed.

  Further, it is preferable to provide a step of urging the female screw portion of the moving member so as to contact the screw portion of the lead screw in a direction along the axial direction of the lead screw.

  Furthermore, it is preferable that the direction in which the moving member is urged includes a stroke in which the direction is reversed at a predetermined position within the moving range of the moving member.

  The direction of biasing the moving member biases the moving member from one side to the other side on one side of the moving range of the moving member, and biases the moving member from the other side to the one side on the other side. It is preferable to provide the process to do.

  Furthermore, it is preferable that the moving member is provided with a process of urging the moving member toward the screw portion from a portion where the screw portion is not formed along the axial center direction of the lead screw.

  The present invention also relates to a feed screw mechanism, comprising: a lead screw having a threaded portion; and a moving member having a female threaded portion that is screwed with the threaded portion of the lead screw, and moves as the lead screw rotates. In the feed screw mechanism configured such that the member is movable along the axial direction of the lead screw, the lead screw is formed with a moving member relief portion that does not interfere with the female screw portion of the moving member, and the moving member relief portion The moving member can be moved within a range where the screw portion of the lead screw is formed.

  Further, the moving member relief portion of the lead screw is preferably a shaft portion that is adjacent to the screw portion and has a smaller diameter than the female screw portion of the moving member.

  Furthermore, it is preferable to provide an elastic member that urges the female screw portion of the moving member to abut on the screw portion of the lead screw in a direction along the axial direction of the lead screw.

  Furthermore, it is preferable that the elastic member is configured to urge the moving member from the moving member relief portion toward the screw portion along the axial direction of the lead screw.

  Moreover, it is preferable that the said elastic member makes the direction which urges | biases a moving member become a reverse direction in the predetermined position in the movement range of a moving member.

  Furthermore, it is preferable that the elastic member is constituted by a coil spring and functions as a tension spring in a predetermined range in which the moving member moves and functions as a compression coil spring in another predetermined range in which the moving member moves.

  Further, it is preferable that the lead screw is formed integrally with a rotating shaft of a motor that drives the lead screw.

  In order to return the screw fitting, the lead screw and the nut part are again turned by reversing the rotation direction of the motor by the load acting in the return direction of the coil spring mounted to suppress the backlash that occurs during screw fitting. The screw fitting can be resumed and a normal feeding operation can be performed.

  According to the feed screw method of the present invention, it is possible to achieve an excellent effect that the screw portion can be prevented from biting and tooth skipping with a simple configuration, the overall length of the device can be shortened, and the overall size of the device can be reduced.

  Specifically, according to the present invention, the lead screw having the threaded portion is rotated to move the moving member having the female screw portion screwed with the threaded portion of the lead screw along the axial direction of the lead screw. In the feed screw method, the lead screw can be rotated while the moving member is positioned in a portion where the screw portion of the lead screw is not formed, so that the lead screw can move due to a motor drive control error that drives the lead screw. Even if an irregular movement outside the range occurs, the moving member moves to the incomplete threaded part of the lead screw, so that the screw fitting is released and the fitting becomes free, and the screw bites and tooth skips. Can be prevented.

  In addition, the screw portion of the lead screw and the female screw portion of the moving member are provided with a step of urging the female screw portion of the moving member so as to abut the screw portion of the lead screw in a direction along the axial direction of the lead screw. It is possible to eliminate the backlash that occurs when the two are screwed together, and to realize accurate conveyance.

  Further, since the direction in which the moving member is urged is provided in a reverse direction at a predetermined position within the moving range of the moving member, backlash is eliminated regardless of the direction in which the moving member is conveyed. Accurate conveyance can be realized.

  The direction of biasing the moving member biases the moving member from one side to the other side on one side of the moving range of the moving member, and biases the moving member from the other side to the one side on the other side. By providing the stroke to perform, it is possible to realize accurate conveyance without backlash regardless of the direction in which the moving member is conveyed.

  Further, the moving member is provided with a process of urging the moving member from the portion where the screw portion is not formed along the axial direction of the lead screw toward the screw portion, so that the moving member is detached from the lead screw and the screw portion. Even if the female screw portion is not screwed, the female screw portion is pressed against the screw portion, so that the moving member can be easily screwed to the lead screw simply by rotating the lead screw in the reverse direction.

  The present invention also relates to a feed screw mechanism, comprising: a lead screw having a threaded portion; and a moving member having a female threaded portion that is screwed with the threaded portion of the lead screw, and moves as the lead screw rotates. In the feed screw mechanism configured such that the member is movable along the axial direction of the lead screw, the lead screw is formed with a moving member relief portion that does not interfere with the female screw portion of the moving member, and the moving member relief portion By making the moving member movable within the lead screw threaded range, even if an irregular operation occurs outside the moving range due to a motor drive control error that drives the lead screw, etc. When the member moves to the incomplete screw portion of the lead screw, the screw fitting is released, the fitting becomes free, and it is possible to prevent screw biting and tooth skipping.

  In addition, since the moving member escape portion of the lead screw is a shaft portion formed adjacent to the screw portion and having a smaller diameter than the female screw portion of the moving member, the female screw portion does not interfere with the lead screw. The screw fitting is released, and the fitting becomes free, so that the screw can be prevented from biting or skipping.

  Furthermore, an elastic member that urges the female screw portion of the moving member to abut on the screw portion of the lead screw in a direction along the axial direction of the lead screw is provided, so that the screw portion of the lead screw and the female screw of the moving member are provided. The backlash generated when the part is screwed together can be eliminated, and accurate conveyance can be realized.

  Furthermore, the elastic member is configured to urge the moving member from the moving member relief portion toward the screw portion along the axial center direction of the lead screw, so that the moving member is detached from the lead screw and the screw portion. Even if the female screw portion is not screwed, the female screw portion is pressed against the screw portion, so that the moving member can be easily screwed to the lead screw simply by rotating the lead screw in the reverse direction.

  Further, the elastic member is configured such that the direction in which the moving member is urged is reversed at a predetermined position within the moving range of the moving member, so that the backlash can be performed regardless of the direction in which the moving member is conveyed. Can be carried out with high accuracy.

  Furthermore, the elastic member is constituted by a coil spring and functions as a tension spring in a predetermined range in which the moving member moves, and functions as a compression coil spring in another predetermined range in which the moving member moves. With the two coil springs, even if the moving member is conveyed in any direction, it is possible to realize accurate conveyance without backlash.

  Further, by configuring the lead screw integrally with the rotating shaft of the motor that drives the lead screw, it is possible to eliminate drive loss and simplify the lead screw drive mechanism.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  1 to 4 are examples of embodiments for carrying out the invention. FIG. 1 is a plan sectional view showing a configuration of a feed screw mechanism provided in an imaging apparatus according to an embodiment of the present invention, and FIG. 2 is the feed screw. FIG. 3 is a plan sectional view showing a state in which the moving member of the mechanism is moved to the rear side, FIG. 3 is a plan sectional view showing a state in which the moving member is moved outside the moving range of the front side, and FIG. It is a plane sectional view showing the state operated to the outside of the movement range. In the figure, the same reference numerals denote the same components, and the basic configuration is the same as the conventional one shown in the figure.

  As shown in FIG. 1, the present embodiment is a lead screw mechanism 2 configured to operate an optical system 7 of an imaging apparatus 1, and a lead screw 4 configured integrally with a rotating shaft of a motor 3. A moving nut 5 that is a moving member screwed to the lead screw 4, and a moving frame 8 that is configured integrally with the moving nut 5 and that holds the optical system 7. Is converted into a linear motion by the lead screw 4 and the moving nut 5, and the moving frame 8 is moved in the front-rear direction along the axial center direction of the lead screw 4.

  The motor 3 and the lead screw 4 are attached to the outer frame body 12 via a lead screw bearing 11 having a U-shaped side cross section.

  The lead screw 4 is formed with a threaded portion 4a in a predetermined range in the middle of the shaft, and the threaded portion 4a interferes with the female threaded portion 5a of the moving nut 5 at both end portions of the threaded portion 4a. In order to avoid this, moving nut relief portions 4b and 4c having a smaller diameter than the female screw portion 5a are formed. The moving nut relief portions 4b and 4c are rotatably held on one end surface 11a on the motor side of the lead screw bearing 11 and the other end surface 11b formed in parallel to face the one end surface 11a.

  The motor 3 has a lead screw side end surface attached to one end surface 11 a of a lead screw bearing 11.

  The lead screw bearing 11 is disposed on the inner side of the outer frame body 12 composed of a front outer frame body 12a and a rear outer frame body 12b. The outer frame body 12 is attached to a case body 22 of an optical system unit attached to the substrate 21.

  The moving frame 8 is slidably held by two guide shafts 13 and 14 that are arranged in parallel with the lead screw 4 at both ends, and moves in parallel following the operation of the moving nut 5. Is provided.

  Both ends of the guide shafts 13 and 14 are fixed to the front outer frame body 12a and the rear outer frame body 12b, the guide shaft 13 is disposed at a position close to the lead screw 4, and the guide shaft 13 is sandwiched therebetween. Thus, a guide shaft 14 is disposed at a position away from the lead screw 4.

  The guide shaft 14 is provided with a coil spring 15 between the moving frame 8 and the rear outer frame body 12b for taking backlash when the screw portion 4a and the female screw portion 5a are screwed together.

  Both ends of the coil spring 15 are coupled to the moving frame 8 and the rear outer frame body 12b, respectively, and the moving nut 5 is pulled and pulled at a position close to the distal end side of the lead screw 4 as shown in FIG. The free length of the spring is set so that the function as a spring is generated and the moving nut 5 is compressed at a position close to the motor 3 side of the lead screw 4 to generate a function as a compression spring as shown in FIG. Has been.

  The moving nut 5 is urged by the coil spring 15 with respect to the lead screw 4 in a direction along the axis of the lead screw. Thereby, the screw part 4a of the lead screw 4 and the female screw part 5a of the moving nut 5 are always screwed together without any backlash.

  Next, the operation of the feed screw mechanism of this embodiment will be described with reference to the drawings.

  Normally, when the optical system of the image pickup apparatus 1 is operated, as shown in FIGS. 1 and 2, the screw 3a of the lead screw 4 is formed by driving the motor 3 and rotating the lead screw 4 forward and backward. The moving nut 5 is moved within the range.

  In the present embodiment, the case where the moving nut 5 advances toward the tip side by the rotation of the lead screw 4 is referred to as “forward rotation”, and the case where the moving nut 5 advances toward the motor 3 side is referred to as “reverse rotation”.

  As shown in FIG. 1, when the moving nut 5 is close to the tip within the range where the threaded portion 4 a is formed, the coil spring 15 is stretched to function as a tension spring, and the moving nut 5 together with the moving frame 8 is a lead screw. 4 is urged toward the motor 3 side (rear side direction), and the internal thread portion of the moving nut 5 and the thread portion 4a of the lead screw 4 are screwed together without backlash.

  As shown in FIG. 2, when the moving nut 5 is close to the motor 3 within the range where the threaded portion 4a is formed, the coil spring 15 is contracted to function as a compression spring, and the moving nut 5 has a moving frame. 8, the lead screw 4 is urged toward the front end side (front side direction), and the female screw portion of the moving nut 5 and the screw portion 4 a of the lead screw 4 are screwed together without backlash.

  As described above, in the lead screw 4, the moving nut 5 is always screwed in a state without backlash as long as it is within a predetermined range where the screw portion 4 a is formed. It can move accurately.

  Here, the case where the moving nut 5 moves beyond the range where the screw portion 5a of the lead screw 4 is formed will be described.

  As shown in FIGS. 3 and 4, when the moving nut 5 moves beyond the moving range (the range where the screw portion 5 a is formed) due to a control error of the motor 3, the moving nut 5 moves the lead screw 4. It enters the nut relief part 4b or 4c. At this time, the screwed state between the female screw portion 5a of the moving nut 5 and the screw portion 4a of the lead screw 4 is released to be in a free state. That is, even if the rotation of the lead screw 4 does not stop, the female screw portion 5a of the moving nut 5 does not bite into the shaft portion of the lead screw 4.

  Next, the case where the moving nut 5 removed from the screw portion 4a of the lead screw 4 is returned to the normal position (the range where the screw portion 4a is formed) will be described.

  In the present embodiment, the coil spring 15 is configured to suppress backlash that occurs due to screw fitting between the screw portion 4a of the lead screw 4 and the female screw portion 5a of the moving nut 5 at all times. Specifically, when the moving nut 5 is close to the tip within the range where the threaded portion 4a is formed, the coil spring 15 is stretched to function as a tension spring, and the motor within the range where the moving nut 5 is formed with the threaded portion 4a. In the case of being closer to the third side, the coil spring 15 is set to be contracted so that the function as a compression spring works.

  Therefore, for example, when the motor 3 is driven in the forward rotation and the moving nut 5 moves to the moving nut relief portion 4b on the distal end side of the lead screw 4 and is detached from the screw portion 4a, the coil spring 15 functions as a tension spring. Therefore, since the moving nut 5 is urged to the end portion on the distal end side, the screw portion 4a of the lead screw 4 and the female screw portion 5a of the moving nut 5 can be obtained simply by rotating the lead screw 4 in the reverse direction. Can be screwed again.

  On the other hand, when the motor 3 is driven in reverse rotation and the moving nut 5 moves to the moving nut relief 4c on the motor 3 side of the lead screw 4 and is detached from the screw portion 4a, the coil spring 15 functions as a compression spring. Therefore, since the moving nut 5 is urged to the end of the screw portion 4a on the motor 3 side, the screw portion 4a of the lead screw 4 and the female screw portion 5a of the moving nut 5 can be obtained by simply rotating the lead screw 4 forward. Can be screwed again.

  Since it comprised as mentioned above, according to this embodiment, since the movement nut relief parts 4b and 4c were formed in the both ends of the thread part 4a of the lead screw 4, when the movement nut 5 operate | moved beyond the movement range Even so, the biting of the moving nut 5 and the lead screw 4 can be avoided.

  Since the lead screw 4 and the moving nut 5 are always screw-fitted with the coil spring 15 without backlash, the moving nut 5 is accurately moved with the rotation of the lead screw 4 by controlling the rotation of the motor 3. can do.

  Further, when the moving nut 5 is positioned closer to the tip of the coil spring 15 within the range where the screw portion 4a is formed, the coil spring 15 is stretched to function as a tension spring, and the moving nut 5 When it is located closer to the motor 3 side, the free length of the spring is set so that the coil spring 15 is contracted and functions as a compression spring, so that the moving nut 5 forms the threaded portion 4 a of the lead screw 4. The lead screw 4 is rotated in the reverse direction (from the normal rotation to the reverse rotation), even if it is overrun on either the tip side (front) or the motor side (rear) beyond the specified range. Alternatively, the moving nut 5 can be easily screwed into the threaded portion 4a without using any other return means simply by rotating from reverse to forward.

  It should be noted that the feed screw method and the feed screw mechanism of the present invention are not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the scope of the present invention.

  For example, in this embodiment, one coil spring 15 functions as a tension spring in a predetermined range in which the moving nut 5 moves, and functions as a compression coil spring in another predetermined range in which the moving nut 5 moves. However, the present invention is not limited to this, and is a moving member as long as the direction in which the moving member is urged is reversed at a predetermined position within the moving range of the moving member. Two coil springs are arranged with the moving frame 8 connected to the moving nut 5 interposed therebetween, and at least one of the coil springs functions as a compression spring within a range in which the moving nut 5 moves. May be. By comprising in this way, backlash can be suppressed by always pressing the moving nut 5 against the lead screw 4 continuously.

  Further, in the present embodiment, the feed screw mechanism is described by taking the imaging apparatus 1 as an example, but the present invention is not limited to this, and for example, in a video camera, a digital still camera, etc. Is also applicable.

It is a plane sectional view showing composition of a feed screw mechanism provided in an imaging device of an embodiment concerning the present invention. It is a top sectional view showing the state where the moving member of the feed screw mechanism was operated to the back side. It is a top sectional view showing the state where the above-mentioned movement member was operated outside the movement range of the front side. It is a top sectional view showing the state where the above-mentioned movement member was operated outside the movement range on the rear side. It is a plane sectional view showing the composition of the conventional feed screw mechanism. It is a plane sectional view showing the state where the moving member of the conventional feed screw mechanism was operated to the front side. It is a top sectional view showing other examples of the conventional feed screw mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Feed screw mechanism 3 Motor 4 Lead screw 4a Screw part 4b, 4c Moving nut relief part 5 Moving nut (moving member)
5a Female thread part 13, 14 Guide shaft 15 Coil spring

Claims (12)

In the feed screw method of moving the moving member having the female screw portion screwed with the screw portion of the lead screw along the axial direction of the lead screw by rotating the lead screw formed with the screw portion,
A lead screw method characterized in that a lead screw can be rotated in a state in which a moving member is positioned in a portion where a screw portion of the lead screw is not formed.   The feed screw method according to claim 1, further comprising a step of urging the female screw portion of the moving member so as to abut on the screw portion of the lead screw in a direction along the axial direction of the lead screw.   The feed screw method according to claim 2, further comprising a stroke in which a direction in which the moving member is urged is reversed at a predetermined position within a moving range of the moving member.   The direction in which the moving member is urged is a process of urging the moving member from one side to the other side on one side of the moving range of the moving member and urging the moving member from the other side to one side on the other side. The feed screw method according to claim 2 or 3, further comprising:   5. The apparatus according to claim 2, further comprising a step of urging the moving member toward a screw portion from a portion where the screw portion is not formed along the axial direction of the lead screw. The feed screw method described in 1. A lead screw having a threaded portion and a moving member having a female screw portion screwed with the threaded portion of the lead screw. The moving member moves along the axial direction of the lead screw as the lead screw rotates. In a feed screw mechanism configured as possible,
The lead screw is formed with a moving member relief portion that does not interfere with the female screw portion of the moving member,
A feed screw mechanism characterized in that the moving member is movable within a range in which the moving member relief portion and the screw portion of the lead screw are formed.   The feed screw mechanism according to claim 6, wherein the moving member relief portion of the lead screw is a shaft portion formed adjacent to the screw portion and having a smaller diameter than the female screw portion of the moving member.   The feed screw according to claim 6 or 7, further comprising an elastic member that urges the female screw portion of the moving member to abut the screw portion of the lead screw in a direction along the axial direction of the lead screw. mechanism.   9. The feed screw mechanism according to claim 8, wherein the elastic member is configured to urge the moving member toward the screw portion from the moving member relief portion along the axial direction of the lead screw.   10. The feed screw mechanism according to claim 8, wherein the elastic member is configured such that a direction in which the moving member is urged is reversed at a predetermined position within a moving range of the moving member.   9. The elastic member is constituted by a coil spring, and functions as a tension spring in a predetermined range in which the moving member moves, and functions as a compression coil spring in another predetermined range in which the moving member moves. The feed screw mechanism according to any one of 1 to 10.   The feed screw mechanism according to any one of claims 8 to 11, wherein the lead screw is configured integrally with a rotating shaft of a motor that drives the lead screw.

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