JP2007315420A - Method and device for removing backlash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for removing backlash capable of removing backlash by a simple structure without causing the decline of torque, increasing torque simultaneously with the removal of backlash, easily performing the drive control of a motor used for removing backlash, and simplifying a motor drive circuit. <P>SOLUTION: A pair of small diameter gears 2, 3 are meshed with the same large diameter gear 1. The backlash of the large diameter gear and the pair of small diameter gears is removed by synchronizing and rotating the small diameter gears by a pair of stepping motors 4, 5 to make tooth surfaces of the small diameter gears contact with the tooth surface of the large diameter gear in a mutually opposite direction in a circumference direction. In-phase coils of the pair of stepping motors are connected in series and the stepping motors are synchronized and driven with predetermined phase differences imparted to rotor shafts thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a backlash removing method and apparatus for removing backlash of a toothed member.

  As a method for removing backlash by meshing a plurality of gears, Patent Document 1 (Japanese Patent Laid-Open No. 9-242831) discloses a load gear provided on a load shaft (output shaft) as a load drive of a load drive motor. In a drive device driven by a gear, an auxiliary gear is meshed with a load driving gear, and this auxiliary gear is rotated by a backlash reduction motor having a smaller output than the load driving motor, and always urged to rotate in one direction. A method of removing backlash between the load gear, the load drive gear, and the auxiliary gear by transmitting the rotation from the auxiliary gear to the load drive gear with a rotational force is disclosed.

  However, this method uses a backlash reduction motor with a smaller output than the load driving motor, and drives the load driving motor to rotate the load driving gear. The backlash reduction motor is driven to rotate the auxiliary gear so that the rotation direction becomes a load with respect to the rotation of the motor. Therefore, for the load drive motor that drives the load, the rotational force of the backlash reduction motor Is always added as another load, and the torque of the load driving motor decreases accordingly.

  In addition, the auxiliary gear and the backlash reduction motor are not directly connected, but the auxiliary gear and a coaxial driven gear are interposed, and the reduction gear directly connected to the backlash reduction motor is engaged with this reduction gear. Since the backlash between the driven gear and the reduction gear is removed by constantly urging the spring in one direction by the spring, the structure becomes complicated.

Furthermore, since the two combinations of the load driving motor and the smaller output backlash reduction motor must be used in the above combination, the adjustment of the combination and the management of the output torque are extremely difficult. It is troublesome.
Japanese Patent Laid-Open No. 9-242831

A first object of the present invention is to provide a backlash removal method and apparatus that can remove backlash with a simple configuration without reducing torque, and that can increase torque simultaneously with backlash removal.
A second problem is to provide a backlash removal method and apparatus that can easily control the drive of a motor used for backlash removal and that can simplify a motor drive circuit.

  According to a first aspect of the present invention, there is provided a backlash removing method in which a pair of rotating tooth bodies respectively rotated by a pair of stepping motors are provided on the same toothed member having a plurality of teeth formed on a circumference or a straight line. The rotor shafts of the pair of stepping motors are mutually set so that the tooth surfaces of the pair of stepping motors are in contact with the tooth surfaces of the toothed member at the opposite side when there is no load, and the pair of stepping motors is driven synchronously By driving the toothed member with the rotating tooth body, the backlash between the toothed member and the pair of rotating tooth bodies is removed from each other.

  The invention according to claim 2 is characterized in that the same-phase coils of the pair of stepping motors are connected in series, and these stepping motors are driven synchronously by giving a predetermined phase difference to their rotor shafts.

  In a third aspect of the invention, the pair of rotating teeth rotated by the pair of stepping motors is a gear, and the toothed member is a gear rotated by the pair of gears.

  In a fourth aspect of the invention, the pair of rotating tooth bodies rotated by the pair of stepping motors is a pinion, and the toothed member is a rack that is linearly driven by these pinions.

  In the invention according to claim 5, the pair of rotating tooth bodies rotated by the pair of stepping motors is a worm, and the toothed member is a worm wheel rotated by the pair of worms.

  According to a sixth aspect of the present invention, there is provided a backlash removing device comprising a pair of rotating tooth bodies respectively rotated by a pair of stepping motors on the same toothed member having a plurality of teeth formed on a circumference or a straight line. The rotor shafts of the pair of stepping motors are mutually set so that the tooth surfaces of the pair of teeth are in contact with the tooth surfaces of the toothed member at the opposite side when no load is applied. By driving synchronously and driving the toothed member with a pair of rotating tooth bodies, backlash between the toothed member and the pair of rotating tooth bodies is removed from each other.

  The invention according to claim 7 is the above device, wherein the same phase coils of the pair of stepping motors are connected in series, and the motor drive circuit gives the pair of stepping motors a predetermined phase difference to their rotor shafts, Synchronous drive rotation is used.

The invention according to claim 8 is characterized in that, in the above apparatus, an encoder for detecting the rotation is attached to only one of the pair of stepping motors.
The invention according to claim 9 is characterized in that, in the above apparatus, the pair of stepping motors has substantially the same structure and the same torque.
According to a tenth aspect of the present invention, in the above apparatus, the torque of the pair of stepping motors is different.

  The invention according to claim 11 is characterized in that, in the above-mentioned device, at least one of the pair of rotating tooth bodies is fixed so as to be finely adjustable in the circumferential direction with respect to the shaft.

  According to the first and sixth aspects of the present invention, the tooth surfaces of the pair of rotating tooth bodies (gear, pinion, worm, etc.) are not relative to the tooth surfaces of the same toothed member (gear, rack, worm wheel, etc.). The rotor shafts of a pair of stepping motors are mutually set so that they are in contact with each other at the opposite side when loaded, and the pair of stepping motors are driven synchronously to drive (rotate) a toothed member with a pair of rotating tooth bodies. Therefore, the backlash can be easily removed by the cooperation of the pair of rotating tooth bodies and the toothed member, and at the same time, one of the pair of rotating tooth bodies is rotated or linearly moved by the toothed member. Since the torque is simultaneously applied to the toothed member during rotation of both rotating tooth bodies, the driving force (output) of the toothed member can be increased.

  When the same-phase coils of a pair of stepping motors are connected in series as in the inventions according to claims 2 and 7 and these stepping motors are given a predetermined phase difference to their rotor shafts and driven synchronously, a pair of stepping motors Since the motor can be driven with exactly the same control as driving one stepping motor without separately controlling the motor, the drive control is simplified.

  As in the invention according to claim 8, when an encoder for detecting the rotation is attached to only one of the pair of stepping motors, the pair of stepping motors can be controlled in a closed loop as if controlling only one stepping motor. The circuit configuration and control can be simplified.

  If the pair of stepping motors has substantially the same structure and the same torque as in the invention according to claim 9, it can be realized easily and economically by using two stepping motors having the same specifications.

  If the torques of the pair of stepping motors are different from each other as in the invention according to claim 10, the driving force (output) of the toothed member can be adjusted according to the torque difference.

  If at least one of the pair of rotating tooth bodies is fixed so as to be finely adjustable in the circumferential direction with respect to the axis as in the invention according to claim 11, the tooth surfaces of these rotating tooth bodies are It is possible to easily perform an initial setting for bringing the tooth surfaces into contact with each other in opposite directions.

  In the preferred embodiment of the present invention, as shown in FIG. 1, the same large-diameter gear 1 (toothed member) on the driven side is rotated by a pair of stepping motors 4 and 5 shown in FIGS. The pair of small-diameter gears (rotating teeth) 2 and 3 on the drive side to be engaged are meshed, and the in-phase coils of the pair of stepping motors 4 and 5 are connected in series as shown in the circuit diagram of FIG. As shown in FIG. 3, the pair of stepping motors 4 and 5 are arranged so that the tooth surfaces of the pair of small diameter gears 2 and 3 are in contact with the tooth surfaces of the large diameter gear 1 in the opposite directions in the circumferential direction when no load is applied. By giving a predetermined phase difference to the rotor shaft by default and driving it synchronously, backlash of the large diameter gear 1 and the pair of small diameter gears 2 and 3 is eliminated.

  In the first embodiment, a pair of rotating gears respectively rotated by a pair of stepping motors has a small diameter spur gear (hereinafter referred to as a small diameter gear), and a toothed member driven by these has a large diameter spur gear (hereinafter referred to as a small gear). This is the case of large diameter gears).

  FIG. 1 is a model diagram of a first meshing contact relationship between the large-diameter gear 1 and the pair of small-diameter gears 2 and 3 in the first embodiment when no load is applied, and FIG. 2 is a model diagram of a second meshing contact relationship. Each is shown. In each of them, a pair of small-diameter gears 2 and 3 are drive-side gears, and the large-diameter gear 1 is a driven-side gear that is rotated by the synchronous rotation of the small-diameter gears 2 and 3 and performs a deceleration action. The pair of small-diameter gears 2 and 3 are exactly the same, but because the meshing contact relationship with the large-diameter gear 1 at no load is different, the teeth 1a, 2a, and 3a on both sides of the three gears 1, 2, and 3 are different. In order to distinguish the direction of the tooth surface, one is expressed as “one side” and the other as “the opposite side”.

  In the case of FIG. 1, when no load is applied, the tooth 2a of one small-diameter gear 2 has a tooth surface 2c on one side thereof in contact with a tooth surface 1b on one side of the tooth 1a of the large-diameter gear 1; The teeth 3a of the small-diameter gear 3 have a meshing contact relationship such that the tooth surface 3b on the opposite side contacts the tooth surface 1c on the opposite side of the tooth 1a of the large-diameter gear 1. That is, when viewed in the middle of the pair of small diameter gears 2 and 3, the tooth surfaces 2c and 3b inside the teeth 2a and 3a are in contact with the tooth surfaces 1b and 1c outside the teeth 1a of the large diameter gear 1. It is in meshing contact relationship. A predetermined phase difference is applied to the rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 directly connected to the pair of small-diameter gears 2 and 3 so as to be in meshing contact when no load is applied. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 are synchronously driven and rotated in the same direction.

  On the other hand, in the case of FIG. 2, when there is no load, the tooth 2a of one small-diameter gear 2 has a tooth surface 2b opposite to the tooth surface 1c opposite to the tooth 1a of the large-diameter gear 1, On the contrary, the tooth 3a of the other small-diameter gear 3 has a meshing contact relationship such that the tooth surface 3c on one side thereof contacts the tooth surface 1b on one side of the tooth 1a of the large-diameter gear 1. That is, when viewed in the middle of the pair of small-diameter gears 2 and 3, the tooth surfaces 2b and 3c outside the teeth 2a and 3a are in contact with the tooth surfaces 1c and 1b inside the teeth 1a of the large-diameter gear 1. It is in meshing relationship. A predetermined phase difference is applied to the rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 directly connected to the pair of small-diameter gears 2 and 3 so as to be in meshing contact when no load is applied. The rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 are synchronously driven and rotated in the same direction.

  In the case of FIG. 1 and the case of FIG. 2, the contact tooth surfaces at the time of no load are reversed in this way, but in either case, the large-diameter gear 1 is clockwise (CW) as shown in FIG. When the pair of small diameter gears 2 and 3 are simultaneously rotated counterclockwise by the pair of stepping motors 4 and 5, the teeth 2a and 3a of the pair of small diameter gears 2 are rotated in the rotational direction ( In the state where the tooth surfaces 2b and 3b on the front side (counterclockwise direction) are in contact with the tooth surface 1c on the rear side of the tooth 1a of the large-diameter gear 1, torque in the clockwise direction is simultaneously applied to the large-diameter gear 1. The diameter gear 1 is rotated clockwise.

  When the pair of stepping motors 4 and 5 are stopped, the pair of small-diameter gears 2 and 3 also stop rotating, and in the case of the meshing contact relationship shown in FIG. 1, the no-load state shown in FIG. In the case of the meshing contact relationship shown in FIG. 4, the state returns to the state shown in FIG. 3, so that in any case, the three gears 1, 2, and 3 cooperate to eliminate backlash.

  On the other hand, when the pair of small diameter gears 2 and 3 are simultaneously rotated clockwise by the pair of stepping motors 4 and 5 in order to rotate the large diameter gear 1 counterclockwise (CCW direction) as shown in FIG. 1 and 2, the teeth 2a and 3a of the pair of small-diameter gears 2 have a tooth surface 2c on the front side in the rotation direction (clockwise direction) and a tooth on the rear side of the teeth 1a of the large-diameter gear 1. While in contact with the surface 1b, a counterclockwise torque is simultaneously applied to the large-diameter gear 1 to rotate the large-diameter gear 1 counterclockwise.

  Also in this case, when the pair of stepping motors 4 and 5 are stopped, the pair of small diameter gears 2 and 3 also stop rotating, and in the case of the meshing relationship shown in FIG. In the case of the meshing relationship shown in FIG. 2, the state returns to the no-load state shown in FIG. 2, so in any case, the three gears 1, 2, and 3 cooperate to remove backlash. Will fit.

  Accordingly, the three gears 1, 2, and 3 cooperate to remove backlash in cooperation with each other regardless of the clockwise direction shown in FIG. 3 or the counterclockwise direction shown in FIG. The torque of gears 2 and 3 is applied to large-diameter gear 1 simultaneously.

  The pair of small-diameter gears 2 and 3 are respectively connected to the large-diameter gear 1 so that the rotor shafts 4a and 5a of the pair of stepping motors 4 and 5 can be finely adjusted at the time of initial setting. On the other hand, it is fixed so that it can be finely adjusted in both directions. As shown in FIG. 6, the fixing is performed by restricting rotation around the rotor shafts 4a and 5a by a fixing screw 12 screwed into the bosses 11 of the small-diameter gears 2 and 3. In FIG. 5, the large-diameter gear 1 is pivotally supported so that the arrangement relationship of the pair of small-diameter gears 2 and 3 with respect to the large-diameter gear 1 is an angular relationship of 90 ° with respect to the axis of the large-diameter gear 1. Although the stepping motors 4 and 5 are attached to the base plate 10 that has been prepared, the present invention is not limited to this.

  FIG. 7 shows a configuration of a motor drive circuit that drives the pair of stepping motors 4 and 5. The stepping motors 4 and 5 are provided with an encoder (rotary encoder) 6 for detecting the rotation of only one of the stepping motors 4. However, the motora itself has substantially the same structure. The A-phase coils 4A and 5A are connected in series, and the B-phase coils 4B and 5B are also connected in series. The A phase coils 4A and 5A are excited by one common A phase drive unit 7A, and the B phase coils 4B and 5B are excited by one common B phase drive unit 7B. Yes.

  Further, in each of the A phase and the B phase, the currents flowing through the coils are detected by the current sensors 8A and 8B, processed by the common current feedback processing unit 9, and the stepping motors 4 and 5 are simultaneously feedback-controlled. The A phase drive unit 7A, the B phase drive unit 7B, and the current feedback processing unit 9 have the same configuration as when one stepping motor is used, and further, the rotation is detected by one encoder 6, so that a closed loop system is configured. Thus, both stepping motors 4 and 5 can be operated in the same manner as a single stepping motor.

Therefore, the motor drive circuit shown in FIG. 7 that drives the stepping motors 4 and 5 in a closed loop system simply connects the coils of the stepping motors 4 and 5 in series for the A phase and the B phase respectively. Only by attaching 6 to the stepping motor 4 on one side, the conventional one that drives one stepping motor can be used as it is.
It is also possible to drive the pair of stepping motors 4 and 5 with an open loop motor drive circuit without an encoder.

  The pair of small-diameter gears 2 and 3 are engaged with the large-diameter gear 1 in a meshing relationship as shown in FIG. 1 or 2 when no load is applied. A predetermined phase difference is mechanically given to the shafts 4a and 5a, and both rotor shafts 4a and 5a rotate simultaneously at the same speed.

An example of the initial setting that makes the two stepping motors 4 and 5 have such a relationship will be described with reference to FIGS.
These stepping motors 4 and 5 have an encoder 6 attached only to one stepping motor 4 and not attached to the other stepping motor 5, so that the former is "motor with encoder" and the latter is "motor without encoder". Called. It is assumed that the small-diameter gears 2 and 3 are already fixed to the rotor shafts 4a and 5a of the stepping motors 4 and 5, respectively.

(1) The motor 4 with the encoder is fixed to the base plate 10, and the motor 5 without the encoder is temporarily fixed to the base plate 10 so that the entire motor 5 can be rotated.
(2) While checking the number of pulses from the encoder 6, the encoderless motor 5 is rotated with respect to the base plate 12. The direction of rotation is to apply tension to the small-diameter gears 2 and 3, so either direction is acceptable.
(3) Since the deviation of the mechanical excitation angles of the motors 4 and 5 can be determined from the number of pulses from the encoder 6, the motor 5 without the encoder is attached to the base plate 10 when the desired excitation angle (number of pulses) is reached. Secure to.

  Now, assuming that both stepping motors 4 and 5 are exactly the same up to the specification and have the same torque characteristics (sin θ), the rotor shafts 4a and 5a simultaneously rotate at the same speed while maintaining a predetermined phase difference as described above. When the phase difference is φ, as shown in FIG. 11, the torque curve of one stepping motor is expressed as sin θ, the torque curve of the other stepping motor is expressed as sin (θ + φ), and the combined torque curve is expressed as sin θ + sin (θ + φ). Can do.

  If the torque characteristic of one of the stepping motors is ½, as shown in FIG. 12, the torque curve is sin (θ + φ) / 2, so the combined torque curve is expressed as sinθ + sin (θ + φ) / 2. be able to.

  Therefore, according to the first embodiment, the backlash of the three gears 1, 2, and 3 can be removed in cooperation as described above, and at the same time, the torque of the large-diameter gear 1 is increased by both stepping motors 4 and 5. Torque adjustment is possible.

  In the first embodiment, the large-diameter gear 1 is substantially used as one gear, and a pair of small-diameter gears 2 and 3 are engaged with each other. However, the large-diameter gear 1 is used as two overlapping gears, respectively. The small gears 2 and 3 may be meshed with each other. It is also possible to make the three gears 1, 2, 3 have the same size and to make a rotation transmission mechanism at the same speed that can prevent backlash.

  In the second embodiment, a pair of rotating tooth bodies respectively rotated by a pair of stepping motors is a pair of worms, and a worm wheel in which a toothed member driven by these rotates.

  In the case of the second embodiment, as shown in FIGS. 13 to 16, a pair of worms 22 and 23 are arranged on both sides of the worm wheel 21 with respect to the same worm wheel 21 so as to mesh with the worm wheel 21 simultaneously. There are two forms as the meshing contact relationship at the time of no load, and FIGS. 13 and 14 show the respective forms.

  In the case of the first form of FIG. 13, the teeth 22 a and 23 a of both worms 22 and 23 are in contact with the tooth surfaces of the teeth 21 a of the worm wheel 21 on the left side of the bisector 24 when viewed from the bisector 24. It has become a relationship.

  In the case of the second form of FIG. 14, contrary to the case of FIG. 13, the teeth 22 a, 23 a of both worms 22, 23 are on the right side of the bisector 24, as viewed from the bisector 24. It is in meshing contact with the tooth surface of the tooth 21a.

In both cases of FIGS. 13 and 14, the meshing contact form is set in a no-load state by giving a predetermined phase difference to the rotor shafts of the pair of stepping motors. By simultaneous rotation of the worms 22 and 23, both torques are simultaneously applied to the worm wheel 21 to rotate clockwise as shown in FIG. 15 or counterclockwise as shown in FIG.
Then, when the pair of worms 22 and 23 are stopped, they return to the respective meshing contact forms when there is no load, so that the pair of worms 22 and 23 and the worm wheel 21 cooperate to remove backlash. Become.

  In the third embodiment, a pair of rotating tooth bodies respectively rotated by a pair of stepping motors is a pair of pinions, and a toothed member driven by these is a rack that moves linearly.

  In the case of the third embodiment, as shown in FIGS. 17 and 18, a pair of pinions 32 and 33 are juxtaposed on one side of the same rack 31 and meshed with the rack 31 at the same time. There are two first and second forms of the meshing contact relationship at the time of no load, and FIGS. 17 and 18 show the respective forms.

  In the case of the first form of FIG. 17, when viewed between the pair of pinions 32, 33, the meshing contact in which the tooth surfaces inside the teeth 32 a, 33 a come into contact with the tooth surfaces outside the teeth 31 a of the rack 31. In contrast, in the case of the second form of FIG. 18, the tooth surfaces on the outside of the teeth 32 a and 33 a of the pair of pinions 32 and 33 are connected to the tooth surfaces on the inside of the teeth 31 a of the rack 31. It is in meshing contact relationship.

  In both cases of FIG. 17 and FIG. 18, the respective meshing contact forms at no load are set by giving a predetermined phase difference to the rotor shafts of the pair of stepping motors. When the pinions 32 and 33 are simultaneously rotated clockwise as shown in FIG. 19, their torques are simultaneously applied to the rack 31 and moved to the left. On the contrary, when the pair of pinions 32 and 33 are simultaneously rotated counterclockwise as shown in FIG. 20, their torques are simultaneously applied to the rack 31 and moved to the right. In both of the clockwise rotation and the counterclockwise rotation, when the pair of pinions 32 and 33 are stopped, the meshing contact form is restored when there is no load, so the pair of pinions 32 and 33 and the rack 31 Cooperate to eliminate backlash.

  In addition to spur gears, worms, and pinions, a pair of rotating tooth bodies that are respectively rotated by a pair of stepping motors may be bevel gears, hypoid gears, toothed pulleys, or the like, and are driven by such rotating tooth bodies. As the toothed member, the present invention can be applied even to a timing belt or the like.

It is a model figure of the 1st meshing contact relationship at the time of no load of the large diameter gear and a pair of small diameter gear in Example 1 of this invention. It is a model figure of a 2nd meshing contact relationship similarly. In the case of FIG. 1 or FIG. 2, it is an engagement state figure when rotating a large diameter gear clockwise. It is a meshing state figure when similarly rotating a large diameter gear counterclockwise. It is a front view shown including a pair of stepping motors which rotate a pair of small diameter gears. It is sectional drawing similarly. It is a circuit diagram which shows a pair of stepping motor and its motor drive circuit. It is a perspective view which shows the relationship between a base plate, a large diameter gear, a pair of small diameter gears, a pair of stepping motors, and one encoder. It is a perspective view which shows the relationship at the time of initial-setting a pair of stepping motor. It is a front view which shows the relationship of the gear at that time. It is a torque curve figure in case a pair of stepping motors have the same torque characteristic. It is a torque curve figure in case the torque of one stepping motor is 1/2. It is a model figure of the 1st meshing contact form of a pair of worm | warm and worm wheel in Example 2 of this invention. It is a model figure of a 2nd meshing contact form similarly. In the case of FIG. 13 or FIG. 14, it is an engagement state figure when rotating a worm wheel clockwise. It is a meshing state figure when similarly rotating counterclockwise. It is a model figure of the 1st meshing contact form of a pair of pinion and rack in Example 3 of this invention. It is a model figure of a 2nd meshing contact form similarly. FIG. 19 is an engagement state diagram when the rack is moved leftward in the case of FIG. 17 or FIG. 18. It is an engagement state figure when moving a rack to the right similarly.

Explanation of symbols

1 Large-diameter gear 1a Large-diameter gear teeth 2/3 Small-diameter gear 2a / 3a Small-diameter gear teeth 1b, 1c, 2b, 2c, 3b, 3c Tooth surface 4, 5 Stepping motor 4a, 5a Rotor shaft 4A, 5A, 4B 5B Coil 6 Encoder 7A Phase A drive unit 7B Phase B drive unit 8A, 8B Current sensor 9 Current feedback processing unit 10 Base plate 11 Boss 12 Fixing screw 21 Worm 21a Worm teeth 22/23 Worm wheel 22a / 23a Worm wheel Teeth 24 Bisecting line 31 Rack 31a Rack teeth 32, 33 Pinions 32a, 33a Pinion teeth

Claims (11)

  A pair of rotating tooth bodies rotated by a pair of stepping motors on the same toothed member formed with a large number of teeth on the circumference or straight line, and the tooth surfaces of the toothed member when the tooth surfaces are unloaded The rotor shafts of the pair of stepping motors are mutually set so as to be in contact with each other on the opposite side, and the pair of stepping motors are driven synchronously to drive the toothed member with the pair of rotating tooth bodies. A backlash removing method, wherein backlashes between the toothed member and the pair of rotating tooth bodies are removed from each other.   The backlash removal method according to claim 1, wherein coils having the same phase of a pair of stepping motors are connected in series, and the stepping motors are driven synchronously by giving a predetermined phase difference to their rotor shafts.   3. The backlash removal according to claim 1, wherein the pair of rotating tooth bodies rotated by the pair of stepping motors is a gear, and the toothed member is a gear rotated by the pair of gears. Method.   The backlash removing method according to claim 1 or 2, wherein the pair of rotating teeth rotated by the pair of stepping motors is a pinion, and the toothed member is a rack that is linearly driven by the pinion. .   The backlash removal according to claim 1 or 2, wherein the pair of rotating teeth rotated by the pair of stepping motors is a worm, and the toothed member is a worm wheel rotated by the pair of worms. Method.   A pair of rotating tooth bodies that are respectively rotated by a pair of stepping motors on the same toothed member formed with a large number of teeth on a circumference or a straight line, the tooth surfaces of the toothed member when the tooth surfaces are unloaded The rotor shafts of the pair of stepping motors are mutually set so as to be in contact with each other on the opposite side. In this state, the pair of stepping motors are synchronously driven by a motor drive circuit, and the pair of rotating tooth bodies A backlash removing device in which backlashes between the toothed member and the pair of rotating tooth bodies are removed from each other by driving the attached member.   The in-phase coils of the pair of stepping motors are connected in series, and the motor drive circuit rotates the pair of stepping motors synchronously by giving a predetermined phase difference to their rotor shafts. The backlash remover described.   8. The backlash removing device according to claim 7, wherein an encoder for detecting the rotation is attached to only one of the pair of stepping motors.   The backlash removing device according to claim 7 or 8, wherein the pair of stepping motors has substantially the same structure and the same torque.   The backlash removing device according to claim 7 or 8, wherein the torque of the pair of stepping motors is different.   The backlash removing device according to any one of claims 6 to 10, wherein at least one of the pair of rotating tooth bodies is fixed so as to be finely adjustable in a circumferential direction with respect to an axis thereof.

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