JP4428930B2 - Motor deceleration drive mechanism with pulsar - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a motor reduction drive mechanism (unit) having a pulsar.
[0002]
[Prior art and its problems]
A motor decelerating drive mechanism having a pulsar is used in various applications, and a zoom drive mechanism of a camera is an example. In the zoom drive mechanism, the rotation output of the motor is transmitted to a rotating cylinder member such as a cam ring through a reduction gear train, and a zooming operation is performed by the rotation of the rotating cylinder member.
[0003]
In such a motor reduction drive mechanism, a pulsar may be arranged in the reduction gear train in order to perform zooming (focal length) control. The pulsar is configured by a combination of a rotating disk having a large number of slits (translucent portions) or reflecting portions at equal intervals in the circumferential direction, and a photocoupler or photoreflector.
[0004]
However, in a motor speed reduction drive mechanism having a conventional pulsar, the pulsar rotating disk is provided in a reduction ratio gear train that decelerates the rotation of the motor, so the resolution of the motor speed (angle) is low and zooming control is performed. The accuracy of was kept low.
[0005]
Further, since it is often provided at a position close to the motor, lubricating oil (oil, grease) attached to the gear of the motor output shaft may scatter and adhere to the rotating disk. When lubricating oil adheres to the rotating disk, the higher the resolution (the narrower the interval between slits), the more clogged the slit and the more difficult it is to detect an accurate pulse. The same applies to a rotating disk provided with a reflecting portion in place of the slit.
[0006]
OBJECT OF THE INVENTION
Accordingly, an object of the present invention is to obtain a motor speed reduction drive mechanism having a pulsar with high resolution.
[0007]
SUMMARY OF THE INVENTION
In the present invention, the problem of the motor reduction drive mechanism having the conventional pulsar occurs because the reduction gear train of the reduction gear train from the motor is large, and the rotation disc of the pulsar is provided in this large reduction gear train. This is based on the viewpoint that if a small reduction ratio gear train is provided separately from the large reduction ratio gear train and a rotating disk is provided here, the problem will be solved.
Further, the present invention provides a small reduction ratio gear train in which a gear provided on the motor output shaft is meshed with the first gear of the large reduction ratio gear train in order to form a small reduction ratio gear train in parallel with the large reduction ratio gear train. The first gear of the gear train is provided so as to rotate coaxially and integrally with the first gear of the large gear ratio gear train, and the large gear ratio gear train and the small gear ratio gear train are brought close to the motor output shaft. If an oil splatter prevention plate is provided between the first stage gear of the large reduction ratio gear train and the first stage gear of the small reduction ratio gear train even if they are positioned, the lubrication adheres to the gear provided on the motor output shaft. This is based on the viewpoint that oil can be prevented from scattering and adhering to the rotating disk in the pulsar disposed in the gear ratio gear train.
[0008]
That is, the motor reduction drive mechanism having a pulser of the present invention, decelerates the motor and a high reduction ratio gear train for decelerating a relatively large speed reduction ratio rotation of the motor, a relatively small speed reduction ratio of the rotation of the motor A gear provided on the output shaft of the motor meshes with a first gear of the large reduction ratio gear train, and a first gear of the small reduction ratio gear train, A pulsar is provided so as to rotate coaxially and integrally with the first stage gear of the large reduction ratio gear train, and in the small reduction ratio gear train, a pulser that generates a pulse corresponding to the rotational speed of the motor is disposed. And the lubricating oil adhered to the gear provided on the output shaft of the motor between the first stage gear of the large reduction ratio gear train and the first stage gear of the small reduction ratio gear train Prevents scattering to the pulsars placed in the gear train Oil scattering prevention plate is characterized by being positioned that.
[0009]
The pulsar is, for example, a rotating disk provided coaxially with the gear of the last stage of the small reduction gear train, a light transmitting part or a reflecting part provided on the rotating disk at equal angular intervals, and a light transmitting part. It can be constituted by a photocoupler that emits light or a photoreflector that emits light to the reflecting portion.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an embodiment of a motor reduction drive mechanism (unit having a pulser according to the present invention. A worm gear 11 is fixed to the output shaft of the motor 10. The worm gear 11 has a large reduction speed. The first-stage two-stage gear 12 of the specific gear train (reduction gear train) meshes with each other, that is, the first-stage second-stage gear 12 has a large-diameter gear 12a that meshes with the worm gear 11 and a small-diameter smaller diameter than the large-diameter gear 12a. A small-diameter gear 12b of the first-stage two-stage gear 12 meshes with a large-diameter gear 13a of the second-stage two-stage gear 13, and a small-diameter integral with the large-diameter gear 13a. The gear 13b meshes with the large-diameter gear 14a of the third-stage two-stage gear 14. The third-stage two-stage gear 14 is integrated with a small-diameter gear 14b (shown only in FIG. 2) having a smaller diameter than the large-diameter gear 14a. Prepared for .
[0013]
The above large reduction ratio gear train decelerates the rotation of the worm gear 11 of the motor 10 to about 1/30 to 1/50, for example, and the small gear 14b in the final stage is moved to the first stage gear (driven) of the driven part. Member) 15. The first-stage two-stage gear 12, the second-stage two-stage gear 13, the third-stage two-stage gear 14, and the driven part first-stage gear 15 are fixed upright on a casing 16 that is fixed to the motor 10. The support shafts 12s, 13s, 14s, and 15s are rotatably supported. The above is a normal large reduction ratio gear train. On the casing 16, there is further provided a support mechanism for a driven gear train that meshes with the first stage gear 15, and these driven portion gear trains are interlocked with, for example, a zoom drive system of a zoom lens barrel. .
[0014]
In this embodiment, a small reduction ratio gear train (small reduction gear train) is provided in parallel with the above large reduction ratio gear train (reduction gear train), and a pulser is provided at the final stage. That is, the small reduction ratio gear train first stage gear 20 is rotatably supported coaxially on the support shaft 12s, and the small reduction ratio gear train first stage gear 20 is coaxially engaged with the support shaft 13s. A rotating disk 22 integrally having a second gear 21 is rotatably supported. The small reduction ratio gear train first-stage gear 20 and the large reduction ratio gear train first-stage two-stage gear 12 are separate bodies, and when engaged with the support shaft 12s, they are engaged with each other and integrated in the rotational direction. Is provided. FIGS. 1 and 3 show the concave and convex shaft 20x on the first gear 20 side. On the first and second gear 12 side, an uneven shaft (not shown) corresponding to the uneven shaft 20x is provided.
[0015]
Small reduction ratio gear train (gear train from worm gear 11 to rotating disc 22), where A is the reduction ratio by the above large gear train (gear train from worm gear 11 to second-stage second gear 13). The reduction ratio B by A is A <B, and B / A is set to about 3 to 5 times, for example.
[0016]
Slits (translucent portions) 22a are formed in the rotating disk 22 at equal angular intervals in the circumferential direction. The rotating disk 22 is sandwiched between the photocoupler support substrate 17 fixed to the casing 16, and the slits. A photocoupler 23 having a pair of a light emitting element that emits light from one of 22a and a light receiving element that emits light from this light emitting element and receives light that has passed through the slit 22a is fixed. The rotating disk 22 and the photocoupler 23 constitute a pulser that emits a pulse corresponding to the rotation speed of the motor 10. Such pulsars are well known.
[0017]
An oil scattering prevention plate 18 is disposed between the first-stage two-stage gear 12 of the large reduction gear train and the first-stage gear 20 of the small reduction gear train that rotate together. The oil scattering prevention plate 18 is formed with a hole 18a through which the support shaft 12s is inserted and a fixing leg 18b. The oil splattering prevention plate 18 is preferably made as large as possible so that the lubricating oil adhered to the worm gear 11 does not fly to the rotating disk 22.
[0018]
When the motor 10 is driven, the worm gear 11 rotates in the motor reduction driving mechanism configured as described above, and the rotation is performed by the first stage two-stage gear 12, the second stage two-stage gear 13, the third stage two-stage gear. 14, and is transmitted to the driven portion first gear 15. At the same time, the first gear 20 of the small reduction ratio gear train rotates integrally with the first and second gears 12, and the rotation is transmitted to the rotating disk 22 via the second gear 21. The slit 22a of the rotating disk 22 cooperates with the photocoupler 23 to generate a pulse corresponding to the rotating speed (angle) of the rotating disk (that is, the rotating speed of the worm gear 11). The pulse generated by the pulser is used for controlling the motor 10. In the present embodiment, since the rotary disk 22 is provided integrally with the gear 21 at the final stage of the small reduction ratio gear train, the number of pulses is the same as that of the large reduction ratio gear train. Therefore, the resolution can be increased as compared with the conventional product.
[0019]
A specific example will be described. Now, the reduction ratio from the worm gear 11 to the first-stage second-stage gear 12 is 1/20, the large-diameter gear 12a, the small-diameter gear 12b, the large-diameter gear 13a, the small-diameter gear 13b, the small-reduction ratio gear train first-stage gear 20, If the number of teeth of the second stage gear 21 is 20, 16, 27, 14, 29, and 14, respectively, the reduction ratio A from the worm gear 11 to the second stage two-stage gear 13 is (1/20) × (16 /27)=1/33.75, whereas the reduction ratio B from the worm gear 11 to the rotating disk 22 is (1/20) × (29/14) = 1 / 9.66.
[0020]
In the above example, in the conventional apparatus, if there is no small reduction ratio gear train and a slit constituting the pulsar is formed in the large-diameter gear 13a, according to the present embodiment, about 3.5 times ( The number of pulses of B / A≈3.5) can be detected.
[0021]
FIG. 4 shows another embodiment of the motor speed reduction drive mechanism according to the present invention. In this embodiment, the oil scattering prevention plate 18 between the first stage two-stage gear 12 of the large reduction gear train and the first stage gear 20 of the small reduction gear train is removed.
[0022]
In the above embodiment, the worm gear 11 is meshed with the first-stage two-stage gear 12 of the large reduction ratio gear train, and the first-stage two-stage gear 12 and the first-stage gear 20 of the small reduction ratio gear train are integrated in the rotation direction. However, a gear that meshes with the worm gear 11 is provided on the side of the first gear 20 of the small reduction ratio gear train, and the first gear 20 and the first gear 12 of the small gear ratio gear train are rotated in the rotational direction. You may couple | bond together.
[0023]
In the above embodiment, the pulsar is configured by the slit of the rotating disk and the photocoupler. However, as described above, the pulsar can be configured by the combination of the reflecting portion of the rotating disk and the photoreflector.
[0024]
【The invention's effect】
According to the present invention, it is possible to obtain a motor deceleration drive mechanism having a pulsar with high resolution.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing an embodiment of a motor speed reduction drive mechanism having a pulsar according to the present invention.
2 is a gear train diagram of a drive system (large reduction ratio gear train) and a pulsar system (small reduction ratio gear train) of the motor reduction drive mechanism of FIG. 1. FIG.
FIG. 3 is a perspective view of the motor deceleration drive mechanism of FIGS. 1 and 2 in an exploded state when viewed from another angle.
FIG. 4 is a perspective view in an assembled state showing another embodiment of a motor speed reduction drive mechanism having a pulsar according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Motor 11 Worm gear 12 1st stage 2 stage gear 13 2nd stage 2 stage gear 14 3rd stage 2 stage gear 15 Driven part 1st stage gear 16 Casing 17 Photocoupler support board 18 Oil scattering prevention plate 20 Small reduction ratio gear Row first gear 21 Second gear 22 Rotating disc 22a Slit 23 Photocoupler

Claims (2)

A motor,
A high reduction ratio gear train for decelerating a relatively large speed reduction ratio rotation of the motor,
And a small speed reduction ratio gear train for decelerating a relatively small speed reduction ratio of the rotation of the motor,
The gear provided on the output shaft of the motor meshes with the first stage gear of the large reduction ratio gear train,
The first gear of the small reduction ratio gear train is provided so as to rotate coaxially and integrally with the first gear of the large reduction gear train;
In the small reduction ratio gear train, a pulser that generates a pulse according to the number of revolutions of the motor is disposed,
Lubricating oil adhered to the gear provided on the output shaft of the motor between the first gear of the large reduction ratio gear train and the first gear of the small reduction gear train is the small reduction ratio gear train. A motor speed reduction drive mechanism having a pulsar, wherein an oil splattering prevention plate for preventing splattering on the pulsar disposed therein is located . In the motor deceleration drive mechanism having the pulsar according to claim 1,
The pulsar, wherein a rotating disc provided on gears coaxial with the last stage of a small reduction ratio gear train, and the light transmitting portion or the reflecting portion provided at equal angular intervals on the rotating disc on, this light transmitting portion A motor decelerating drive mechanism having a pulser comprising a photocoupler that emits light or a photoreflector that emits light to a reflecting portion.

Images