JP2002013902A - Precision apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precision apparatus capable of lowering the cost of mounting a spiral spring therein and suitable for mass-production. SOLUTION: In order to prevent backlash in a gear mechanism 4, a gear 6 for backlash prevention and the spiral spring 7 pre mounted in an apparatus body 2. The gear 6 is equipped with a shaft part 23 connected to the spring 7. The spring 7 has a lock part 7B formed by bending its inner end part and the lock part 7B is engaged with a groove 23E formed in the shaft part 23. By inserting the lock part 7B formed on the inside end part of the spring 7B into the groove 23E of the shaft part 23, the spring 7 can be mounted on the shaft part 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision instrument in which a gear mechanism is provided in a measuring instrument main body, and a backlash preventing gear for preventing backlash of the gear mechanism and a spiral spring are respectively attached to the instrument main body. , Measuring instruments, watches and the like.

[0002]

2. Description of the Related Art There are known various measuring instruments such as mechanical and lever type dial gauges, micrometers, dial calipers, etc., which mechanically read the amount of linear displacement via a spindle. This type of measuring device includes a device main body, a gear mechanism provided in the device main body, and a spindle and a needle that are respectively linked to the gear mechanism. Displacement of the spindle is transmitted to the needle via the gear mechanism. The linear displacement is read from the needle displacement.

Generally, a backlash is generated in a gear mechanism including a plurality of gears, and a gear and a spiral spring for preventing the backlash are provided in the apparatus body. A spiral spring is formed by winding a band-shaped material having a uniform cross section in a spiral shape on a plane, and is sometimes referred to as a mainspring spring. The spiral spring has an inner end attached to a shaft connected to a backlash prevention gear, and an outer end (open end) attached to the device body. Conventionally, the inner end of the spiral spring is attached to the shaft using a metal ring.

In other words, conventionally, as shown in FIG. 5 (A), the inner end of a spiral spring 60 is screwed to a metal ring 50 having a locking hole 50A for locking the shaft. Some are fixed at 61. Further, as shown in FIG. 5B, the inner end of the spiral spring 60 is fitted into a groove 50B formed by lathing on the outer periphery of the metal ring 50, and this inner end is joined to the periphery of the metal ring 50. Some surfaces are stopped by welding 62.

As shown in FIG. 5C, the inner end of the spiral spring 60 is engaged with a groove 50C formed at a predetermined depth from the end face of the metal ring 50 by milling, and the spiral is formed. There is one that caulks the side 60A of the inner end of the spring 60. Further, as shown in FIG.
There is a type in which the inner end of the spiral spring 60 is fitted into the groove 50B of the metal ring 50, and the ribs 50D formed on both outer sides of the groove 50B of the metal ring 50 are engaged with the inner end. .

Conventionally, the outer end of the spiral spring is attached to the main body of the apparatus by using a taper pin. In this conventional example, a hole is formed in the device main body, and a taper pin is press-fitted into the hole with the outer edge of the spiral spring sandwiched therebetween. Since the tapered pin is a small part, the press-fitting into the hole is performed manually. Further, there is a conventional example in which the outer end of the spiral spring is attached to the device body by swaging the spiral spring.

[0007]

In the structure for attaching the inner end of the spiral spring to the shaft, in the conventional example shown in FIG. 5A, since the spiral spring 60 is attached with the screw 61, the screwing operation is troublesome. Take it. In particular, since many measuring instruments such as dial gauges are miniaturized, the screw 61 and the metal ring 50 are also small, and the work of attaching the spiral spring 60 using the screw 61 is complicated. In the conventional example shown in FIG. 5B, the spiral spring 60 is welded.
The metal ring 5 is fixed as described above.
Since 0 is small, the welding operation is complicated and time-consuming.

In the conventional example shown in FIG. 5C, a groove 50C is formed on the end face of the metal ring 50.
The operation of forming the groove 50C in the small metal ring 50 by milling and the operation of caulking the side portion 60A of the spiral spring 60 are complicated and time-consuming. In the conventional example shown in FIG. 5D, the rib 50D of the metal ring 50 is swaged, but the operation of swaging the rib 50D of the small metal ring 50 is complicated and time-consuming. That is, in the above-described conventional example, the spiral spring 60 is attached to the metal ring 50 manually, and this operation is complicated. Further, in addition to the shaft provided in the gear mechanism, a metal ring 50 and, if necessary, a screw 61 are required.
The number of parts increases.

In the conventional structure using a tapered pin in the structure for attaching the outer end of the spiral spring to the apparatus body, the cost of the tapered pin is high. Further, since the taper pin is manually pressed into the hole of the apparatus main body, the operation is complicated. In addition, when the tapered pin is press-fitted, the spiral spring may be displaced. In this case, it is necessary to adjust the shape of the spiral spring, and the operation is complicated from this point as well. Further, in the conventional example in which the spiral spring is swaged, the work of fastening is complicated and time-consuming. For this reason, in the conventional example in which the inner end of the spiral spring is attached to the shaft and the conventional example in which the outer end of the spiral spring is attached to the device body, the manufacturing cost of the measuring device using the spiral spring is high, and the work is not required. There is a problem that there is a limit in mass production because of the complexity.

[0010] An object of the present invention is to provide a precision instrument that can be manufactured at a low cost and can be mass-produced when attaching a spiral spring.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an engagement piece formed by bending the inner end of a spiral spring and locking it in a groove of a shaft, or twisting the outer end of the spiral spring. Is locked to the device body to achieve the above object. Specifically, the precision instrument of the present invention comprises an apparatus body, a gear mechanism provided in the apparatus body, a backlash prevention gear attached to the apparatus body to prevent backlash of the gear mechanism, and A precision device comprising a spiral spring, wherein the gear for preventing backlash includes a shaft connected to the spiral spring, and the spiral spring has a locking portion having an inner end bent. The locking portion is engaged with a groove formed in the shaft portion.

In the present invention, the spiral spring can be attached to the shaft by inserting the locking portion formed at the inner end of the spiral spring into the groove of the shaft. After the spiral spring is attached to the shaft, the spring spring generates a spring force in the contraction direction, so the locking portion of the spiral spring tightens the shaft, and the spiral spring and the shaft are fixed. Is done. Therefore, according to the present invention, the conventionally used metal rings, screws and the like are not required, so that the manufacturing cost can be reduced. Moreover, since the operation of attaching the spiral spring is completed only by inserting the locking portion of the spiral spring into the groove of the shaft portion, the operation of attaching the spiral spring can be automated, and mass production of precision equipment becomes possible.

Here, in the present invention, the shaft portion has a holding portion for holding the inner end of the spiral spring, and a retaining member for holding the inner end of the spiral spring held by the holding portion. The structure provided with a part is preferable. In this configuration,
After holding the inner end of the spiral spring with the shaft holder,
Since the inner end of the spiral spring is prevented from coming off by the retaining portion, the spiral spring does not accidentally come off the shaft.

Further, the precision instrument of the present invention comprises:
A precision device comprising a gear mechanism provided in the device main body, a backlash prevention gear and a spiral spring respectively attached to the device main body to prevent backlash of the gear mechanism, wherein the spiral spring is ,
The device main body includes an engagement piece formed by twisting an outer end thereof, and the device main body includes a projection provided on the device main body while preventing movement of the engagement piece of the spiral spring. It is characterized by the following.

According to the present invention, the engagement piece formed at the outer end of the spiral spring is engaged with the projection of the equipment main body.
The spiral spring can be attached to the device body. After the spiral spring is attached to the device main body, the engaging piece of the spiral spring is formed by twisting, so that even if a spring force in the contraction direction is generated in the spiral spring, the force is orthogonal to the plane of the engaging piece. To be distributed in a direction substantially parallel to the plane direction,
The engagement piece is less likely to bend and does not accidentally come off the projection. Therefore, according to the present invention, a conventionally used taper pin is not required, and the manufacturing cost can be reduced. In addition, the work of attaching the spiral spring is completed simply by engaging the engagement piece of the spiral spring with the projection of the device body, so that the work of attaching the spiral spring can be automated, and mass production of precision equipment is possible. Become. Further, since there is no displacement of the spiral spring due to the press-fitting operation of the taper pin, the mounting operation is simplified.

Here, in the present invention, it is preferable that the engaging piece is formed by twisting the outer end of the spiral spring at a right angle. With this configuration, when a spring force in the contraction direction is applied to the spiral spring, the force acts along the substantially flat surface of the engagement piece, so that the engagement piece is reliably prevented from being bent and accidentally coming off the projection. can do. Moreover, it is preferable that the protrusions are arranged at two positions with the engaging piece of the spiral spring interposed therebetween. In this configuration, the engagement pieces are sandwiched between the protruding portions facing each other, so that the displacement of the engagement pieces can be reliably prevented.

[0017]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view showing a schematic configuration of a mechanical dial gauge 1 which is a precision instrument of the present embodiment. In FIG. 1, the dial gauge 1 is
A device main body 2, a spindle 3 provided on the device main body 2 so as to be able to advance and retreat, a gear mechanism 4 connected to the spindle 3 and provided on the device main body 2, and hands 5A and 5B interlocked with the gear mechanism 4. The gear mechanism 4 includes a backlash preventing gear 6 for preventing backlash, and a spiral spring 7 connected to the gear 6.

The apparatus main body 2 includes a substantially flat cylindrical casing 10, a back cover 11 provided on an end face of the casing 10, and a substantially flat base plate provided inside the casing 10 to which the gear mechanism 4 is attached. 12 and a bearing plate 13 having a substantially U-shaped cross section, a dial 14 and a scale plate 15 arranged in parallel with the main plate 12, respectively, and an outer frame 16 which covers the scale plate 15 and is attached to an end face of the casing 10.
It is comprised including. A substantially cylindrical support member 17 for guiding and supporting the spindle 3 is provided on an outer peripheral portion of the casing 10, and a rubber cap 18 is provided at a tip of the support member 17. A cap 19 is provided on the outer periphery of the casing 10 on the opposite side of the support member 17.

A rack (not shown) is formed on the side surface of the spindle 3, and this rack is connected to the gear mechanism 4. The spindle 3 is constantly urged in a projecting direction by a coil spring (not shown). The gear mechanism 4 includes a needle 5A
A center pinion 20 connected to the backlash prevention gear 6 and a large gear 21 connected to the needle 5B;
A small gear and an intermediate gear (not shown) interlocked with these gears are provided.
3 rotatably supported. The large gear 21 is composed of a small-diameter gear portion 21 </ b> A interlocked with the spindle 3 and a center pinion 2.
0 and a large-diameter gear portion 21B that meshes with each other. The needle 5A is a long hand, and the needle 5B is a short hand. The amount of movement (displacement) of the spindle 3 is displayed by these hands 5A and 5B.

FIGS. 2 to 4 show the mounting structure of the backlash preventing gear 6 and the spiral spring 7. FIG. FIG.
FIG. 4 is a cross-sectional view showing a mounting structure of the backlash prevention gear 6 and the spiral spring 7. In FIG. 2, the backlash preventing gear 6 includes a gear body 22 and the gear body 2.
2, a shaft 23 provided at the center of rotation of the spiral spring 7 and connected to the inner end of the spiral spring 7. One end of the shaft 23 is rotatably supported by the base plate 12, and the other end is a bearing plate. 13 is rotatably supported.

The shaft portion 23 has a holding portion 23A for holding the inner end of the spiral spring 7, and a cone provided at the end of the holding portion 23A for facilitating insertion of the spiral spring 7 into the holding portion 23A. A portion 23B, a retaining portion 23C for retaining the inner end of the spiral spring 7 held by the holding portion 23A, and a shaft supporting portion 23D formed through the holding portion 23A and the conical portion 23B. You. The holding portion 23A is formed in a stepped cylindrical shape, and a groove 23E for engaging the inner end of the spiral spring 7 is formed in the outer peripheral portion of the holding portion 23A so as to extend in the axial direction along the axial direction. Have been. This groove 23
A plurality of, for example, four Es are formed at equal intervals on the outer periphery of the holding portion 23A.

The retaining portion 23C is formed integrally with the shaft supporting portion 23D, and one side of the substantially triangular plate is
It is fitted in a fitting groove 23F formed in 3A. In the retaining portion 23C, one side intersecting with the one side is formed continuously with the tapered surface of the conical portion 23B, and the remaining one side is
The inner end of the spiral spring 7 is sandwiched between the stepped portion of 3A. In FIG. 2, a plurality of retaining portions 23C are provided, but one may be provided.

FIG. 3 shows the structure of the spiral spring 7. FIG. 3A is a plan view of the spiral spring 7, and FIG.
(B) is a sectional view thereof. In FIG. 3, a spiral spring 7 is formed by winding a band-shaped material having a uniform cross section in a spiral shape on a plane, and is called a mainspring spring. The spiral spring 7 is formed by bending a spring main body 7A at a substantially right angle inside the spring main body 7A and forming the groove 2 of the holding portion 23A.
It is formed of a locking portion 7B to be engaged with 3E and an engagement piece 7C formed by being twisted at a right angle to the spring main body 7A outside (open end side) of the spring main body 7A. The spiral spring 7 has a locking portion 7B at the inner end thereof and a holding portion 23A.
4, the spring force is generated in the contraction direction (direction P toward the holding portion 23A) as shown in FIG. 4, so that the locking portion 7B tightens the holding portion 23A. Become.

In FIG. 2, the base plate 12 has a mounting portion 12A protruding toward the bearing plate 13 side. The mounting portion 12A has a cylindrical shape for preventing movement of the engaging piece 7C of the spiral spring 7. A projection 12B is provided. The protruding portions 12B are arranged at two locations facing each other with the engaging piece 7C of the spiral spring 7 interposed therebetween (see FIG. 3). Therefore, the movement of the engagement piece 7C of the spiral spring 7 in the plane is restricted. After the spiral spring 7 is attached to the protruding portion 12B, the engaging piece 7C of the spiral spring 7 is formed by being twisted at a right angle. Since it is transmitted within the plane of the engagement piece 7C,
This engaging piece 7C does not bend. Bearing plate 13
An elastic pressing portion 13 </ b> A is integrally formed at a portion facing the base plate 12. The pressing portion 13A has an engagement piece 7C of the spiral spring 7 with its tip portion between the pressing portion 13A and the mounting portion 12A.
Is sandwiched. The bearing plate 13 is attached to the main plate 12 with screws 24.

To assemble the dial gauge 1 having such a configuration, the back cover 11 is attached to the casing 10, the spindle 3 is attached, and the gear mechanism 4 is assembled inside the casing 10. Further, the base plate 12 and the bearing plate 1
3, a backlash preventing gear 6 and a spiral spring 7 are attached. Therefore, the backlash preventing gear 6 is arranged on the main plate 12 and the spiral spring 7 is attached to the gear 6.

At this time, the inner end of the spiral spring 7 is pressed against the gear body 22 while being guided by the conical portion 23B of the shaft portion 23. Then, the inner end of the spiral spring 7 is guided to the holding portion 23A through the side surface of the retaining portion 23C. Thereafter, the locking portion 7B at the inner end of the spiral spring 7 is fitted into the groove 23E. Further, an engagement piece 7C at the outer end of the spiral spring 7
Is locked between two projections 12B formed on the mounting portion 12A of the base plate 12.

Thereafter, the bearing plate 13 is screwed to the base plate 12 with screws 24.
Attach with When the bearing plate 13 is attached to the base plate 12, the engaging portion 7A of the spiral spring 7 is pressed by the pressing portion 13A of the bearing plate 13 and does not come off from the bearing plate 13 and the base plate 12. The base plate 12 and the bearing plate 13 to which the backlash prevention gear 6 and the spiral spring 7 are attached are mounted inside the casing 10, and further, the dial 14 and the scale plate 15 are attached, and the hands 5A and 5B are connected to the gear mechanism 4. Attach to Finally, the outer frame 16 and the cap 19 are attached to the casing 10.

Therefore, in the present embodiment, the backlash preventing gear 6 used in the dial gauge 1 is provided with the gear body 22 and the shaft 23 connected to the spiral spring 7. 7 has a structure having a locking portion 7B whose inner end is bent, and the locking portion 7B is engaged with the groove 23E formed in the shaft portion 23.
By inserting the locking portion 7B of the spiral spring 7 into the groove 23E of the shaft portion 23, the spiral spring 7 can be attached to the shaft portion 23. Therefore, when attaching the inner end portion of the spiral spring 7 to the backlash prevention gear 6, a conventionally used metal ring, screw, and the like are not required.
Manufacturing costs can be reduced. In addition, the shaft 23
By simply inserting the locking portion 7B of the spiral spring 7 into the groove 23E, the mounting operation of the spiral spring 7 is completed, so that the mounting operation of the spiral spring 7 can be automated, and the mass production of the dial gauge 1 becomes possible. .

Further, in this embodiment, the shaft 23 is provided with a holding portion 23A for holding the inner end of the spiral spring 7, and a retaining member for holding the inner end of the spiral spring 7 held by the holding portion 23A. Since the inner end of the spiral spring 7 is held by the holding portion 23A of the shaft portion 23, the inner end of the spiral spring 7 is stopped by the retaining portion 23C. It does not come off the shaft portion 23 by mistake. Moreover, since the retaining portion 23C is formed as a substantially triangular plate, the structure of the retaining portion 23C can be simplified.

Further, since the retaining portion 23C is fitted into the fitting groove 23F formed in the holding portion 23A, the work of attaching the retaining portion 23C to the holding portion 23A can be facilitated. Further, since the conical portion 23B is continuously formed on the holding portion 23A of the shaft portion 23, the insertion of the spiral spring 7 into the holding portion 23A becomes easy, and the work of attaching the spiral spring 7 to the shaft portion 23 is performed from this point. Also becomes easier.

In this embodiment, the spiral spring 7 used in the dial gauge 1 is provided with a spring main body 7A and an engaging piece 7C formed by being twisted with respect to the spring main body 7A. 12 is an engaging piece 7C of the spiral spring 7
Since the protruding portion 12B for preventing the movement is provided, the conventionally used taper pin is not required, and the manufacturing cost can be reduced. Moreover, the protruding portions 1 of the base plate 12
By simply engaging the engagement piece 7C of the spiral spring 7 with 2B, the mounting operation of the outer end of the spiral spring 7 is completed, so that the mounting operation of the spiral spring 7 can be automated, and mass production of the dial gauge 1 can be achieved. Becomes possible. Further, since there is no displacement of the spiral spring 7 due to the press-fitting operation of the taper pin, the mounting operation is also simplified from this point.

Further, since the engagement piece 7C is formed by being twisted at right angles to the spring body 7A, when a spring force in the contraction direction is generated in the spiral spring 7 after the attachment, the force is applied to the engagement piece 7C. , The engagement piece 7C can be reliably prevented from being bent and accidentally disengaged from the projection 12B. In addition, since the protrusions 12B are arranged at two locations facing each other with the engagement piece 7C of the spiral spring 7 interposed therebetween, the engagement pieces 7C are opposed to each other.
Therefore, the displacement of the engagement piece 7C can be reliably prevented.

The pressing portion 1 having elasticity is provided on the bearing plate 13.
3A are integrally formed, and the tip of the pressing portion 13A and the main plate 1 are formed.
Since the engaging piece 7C of the spiral spring 7 is sandwiched between the mounting part 12A and the second mounting part 12A, after the bearing plate 13 is attached to the main plate 12, the engaging piece 7C moves in a direction orthogonal to the plane thereof. Since it does not occur, it is possible to prevent the engaging piece 7C from being accidentally detached from the mounting portion 12A.

The present invention is not limited to the configuration of the above embodiment, but includes the following modifications as long as the object of the present invention can be achieved. For example,
In the above embodiment, the precision device is a mechanical dial gauge 1, but the precision device of the present invention is a lever type dial gauge, a micrometer, a measuring device for measuring the length of a dial caliper, and other measuring devices. Alternatively, it may be a mechanical timepiece.

In the above embodiment, the shaft portion 23 is provided with the holding portion 23A and the retaining portion 23C. However, in the present invention, the retaining portion 23C is omitted and the shaft portion 23 is formed only from the retaining portion 23A. It may be configured. Even if the retaining portion 23C is provided, the shape is not limited to the above embodiment. For example, a rib continuously formed on the outer peripheral surface of the holding portion 23A may be used.

In the above-described embodiment, the engaging piece 7C of the spiral spring 7 is formed by twisting at right angles to the spring main body 7A, but the angle is arbitrary, for example, 30 degrees, 45 degrees.
Degrees may be 60 degrees. Further, the number of the protrusions 12B is not limited, and the engagement pieces 7 of the spiral spring 7 are not limited.
If it is arranged to regulate the force acting on C, 1
Or three or more. Furthermore,
It is not always necessary to provide the pressing portion 13A.

[0037]

According to the present invention, an apparatus main body, a gear mechanism provided on the apparatus main body, a backlash preventing gear and a spiral which are respectively attached to the apparatus main body to prevent backlash of the gear mechanism. A precision device comprising a spring, the backlash prevention gear includes a shaft connected to the spiral spring, and the spiral spring has a locking portion having an inner end bent. Since the locking portion is engaged with the groove formed in the shaft portion, the locking portion formed at the inner end of the spiral spring is inserted into the groove of the shaft portion, so that the spiral spring is connected to the shaft portion. Can be attached to This eliminates the need for conventionally used metal rings, screws, and the like, thereby reducing manufacturing costs and, furthermore, simply inserting the locking portion of the spiral spring into the shaft groove to mount the spiral spring. Since the work is completed, the work of attaching the spiral spring can be automated, and mass production of precision equipment becomes possible.

Further, according to the present invention, the apparatus main body, the gear mechanism provided in the apparatus main body, the backlash preventing gear and the spiral which are respectively attached to the apparatus main body to prevent the gear mechanism from backlash. A precision device comprising a spring, wherein the spiral spring includes an engagement piece formed by twisting an outer end thereof, and the device main body prevents movement of the engagement piece of the spiral spring. And a projection provided on the device main body, so that the spiral spring can be attached to the device main body by engaging an engagement piece formed on an outer end portion of the spiral spring with the projection of the device main body. . This eliminates the need for a conventionally used taper pin, thereby reducing manufacturing costs. In addition, by simply engaging the engagement piece of the spiral spring with the projection of the device main body, the work of attaching the spiral spring can be performed. Is completed, the work of attaching the spiral spring can be automated,
Mass production of precision equipment becomes possible.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a dial gauge according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of the embodiment.

3A is a plan view of a spiral spring, and FIG. 3B is a cross-sectional view of the spiral spring.

FIG. 4 is a cross-sectional view showing a state where the inner end of the spiral spring and the shaft are mounted.

FIGS. 5A to 5D are perspective views showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Precision instrument (dial gauge) 2 Equipment main body 4 Gear mechanism 6 Backlash prevention gear 7 Spiral spring 7B Locking part 7C Engagement piece 12 Main plate 12A Mounting part 12B Projection part 13 Bearing plate 13A Pressing part 22 Gear body 23 Shaft 23A Retaining part 23C Retaining part 23E Groove

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mikio Suzuki 1688-189 Nasutagawa, Nakatsugawa City, Gifu Prefecture Mitutoyo Co., Ltd. (72) Inventor Toshiyuki Shinohara 1688-189 Nasugagawa, Nakatsugawa City, Gifu Prefecture Mitutoyo Co., Ltd. (72) Inventor Munenori Ishii 1688-189 Nasutagawa, Nakatsugawa City, Gifu Prefecture (72) Inventor Koichi Adachi 1688-189 Nasugagawa, Nakatsugawa City, Gifu Prefecture F Term (reference) VV48

Claims (4)

[Claims] 1. A precision device comprising: a device main body; a gear mechanism provided in the device main body; and a backlash prevention gear and a spiral spring respectively attached to the device main body to prevent backlash of the gear mechanism. In the apparatus, the backlash prevention gear includes a shaft connected to the spiral spring, and the spiral spring has a locking portion formed by bending an inner end thereof. A precision device, wherein the precision device is engaged with a groove formed in the shaft portion. 2. The precision instrument according to claim 1, wherein the shaft portion passes through a holding portion for holding an inner end of the spiral spring and an inner end of the spiral spring held by the holding portion. A precision instrument comprising a retaining portion for stopping. 3. A precision device comprising: a device main body; a gear mechanism provided in the device main body; a backlash preventing gear and a spiral spring respectively mounted on the device main body to prevent backlash of the gear mechanism. An apparatus, wherein the spiral spring includes an engagement piece formed by twisting an outer end of the spiral spring, and the apparatus main body prevents movement of the engagement piece of the spiral spring and is provided on the apparatus main body. A precision instrument characterized by comprising a protruding portion. 4. The precision device according to claim 3, wherein an outer end of the spiral spring is twisted at a right angle to form the engaging piece, and the protrusion sandwiches the engaging piece of the spiral spring. Precision equipment, characterized in that they are arranged in two places.