GB2290364A

GB2290364A - Vibration generating motor for a portable alerting apparatus, eg pager

Info

Publication number: GB2290364A
Application number: GB9511433A
Authority: GB
Inventors: Teruyuki Motohashi; Masahide Ishino
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 1994-06-08
Filing date: 1995-06-06
Publication date: 1995-12-20
Anticipated expiration: 2015-06-06
Also published as: CN1056478C; JPH07336940A; CN1121651A; KR0185738B1; GB9511433D0; KR960002172A; GB2290364B; JP2538764B2

Description

- 1 VIBRATION GENERATING MOTOR FOR A PORTABLE APPARATUS 2290364 The

present invention relates to a vibration generating motor applicable to a portable apparatus of the type producing an alert in the form of vibration and, more particularly, to a vibration generating motor highly resistive to shocks and impacts.

A radio pager or similar extensively used today has an alerting device for alerting the user to the receipt of a call. The alerting device is usually 1 0 implemented as a speaker for generating sound or a miniature motor for generating vibration. semicircular eccentric weight i miniature portable apparatus The motor may include a mounted on an output shaft extending out from the easing of the motor, as taught in Japanese Utility Model Laid-Open Publication No. 4-131166 b y 1 5 way of example. Alternatively, the semicircular eccentric weight may be disposed in the casing. In any case, the weight is rotated integrally with the output shaft to generate vibration.

Features of a vibration generating motor to be described below, as an example, are that it is suitable for a portable apparatus and has a structure which is free ftom deformation attributable to shocks and impacts, and which promotes miniaturization and easy production.

A particular vibration generating motor to be described below has a casing accommodating the body of the motor, an output shaft extending out from the casing 1 0 and for transmitting the rotation of the body, a weight mounted on the output shaft and including an eccentric body portion and a non- eccentric cylindrical portion, and a holder holding the motor. The gap between the holder and the cylindrical portion is less than the elastic deformation range of the output shaft.

1 5 A known vibration generating motor will now be described, together with, by way of example, arrangements which embody the invention, with reference to the accompanying drawings, in which:- FIGS. IA anti IB are respectively an external perspective view and a front view showing a conventional vibration generating motor; FIG. 2 conventional FIG. 3 1 5 is an external perspective view of another vibration generating motor; is a side elevation showing the problem of the conventional vibration generating motor which the inventors of the present application found; FIGS. 4A and 413 are respectively a side elevation and a 1 0 front view showing a vibration generating motor embodying the present invention; FIGS. SA and 5B are respectively a side elevation and a front view showing an alternative embodiment of the present invention; FIG. 6A is an external perspective view showing another alternative embodiment of the present invention together with the easing of a portable apparatus; and FIGS. 613 and 6C are respectively a side elevation and a front view of the motor and casing shown in FIG. SA.

To better understand the present invention, a brief description will be made to a conventional motor of the kind concerned, shown in FIGS. IA and IB. As shown in FIG. IA, 2 5 the motor, generally 10, has a casing 12 and an output shaft 14 extending out from the casing 12. A semicircular eccentric weight 16 is mounted oil tile output shaft 14. The weight 1 6 is rotated integrally with the shaft 14, thereby generating vibration. This kind of motor is disclosed in, for example, previously mentioned Japanese Utility Model Laid-Open Publication No. 4-131166.

However, the inventors of the present application found that when an apparatus loaded with the motor 10 is, for example, let fall, the resulting impact is apt to cause the shaft 14 to noticeably deform at its root portion toward the side where the weight 16 is absent, as indicated by a phantom line in FIG. 3. This is because the weight 16 has a semicircular configuration.

The inventors oi the present application contemplated various measures against the deformation of the shaft, e.g., increasing the diameter of the shaft and using a hard material for the shaft. However, the diameter and hardness of the shaft were limited in relation to the miniaturization of the motor.

2 0 FIG. 2 shows another conventional motor also taught in the above Laid-Open Publication No. 4-131166. As shown, the motor which reduces motor sound, generally 10A, has a casing 12 and a semicircular eccentric weight 16a disposed in the casing 12. The shaft of the motor 10A suffers from a 2 5 minimum of plastic deformation attributable to animpact 1 because the displacement of the weight 14a is limited by the inner periphery of the easing 12a. However, the motor IOA has a complicated structure and is difficult to miniaturize.

compared to the motor 10, FIGS.]A and 113, having the weight 16 outside of the casing 12. In addition, the motor JOA needs a special production procedure.

Referring to FIGS. 4A and 4B, a motor embodying the present invention will be described. As shown, the motor 30, generally 30, has a casing 32 which is held by holders 34 and 36. A semicircular eccentric weight 40 is made of a material having a great specific weight and is mounted on an output shaft 38 extending out from the casing 32.

rotated integrally with the shaft 38, The weight 40 is thereby generating vibration. To prevent the shaft 38 from deforming, a non 1 5 eccentric cylindrical portion 40a is formed at the end of the weight 40 remote from the casing 32. ne cylindrical portion 40a has a size (diameter) preselected such that gaps 42 at four positions where it is closest to the holders 34 and 36 are less than the elastic deformation range of the material constituting 2 0 the shaft 38.

Assume that the shaft 38 is deformed due to the fall of an apparatus loaded with the motor 30. Then, when the motor 30 is driven to generate vibration, the cylindrical portion 40a is rotated together with (lie shaft 38 and weight 40. At this instant, the cylindrical portion 40a hits against and is restricted by (lie inner peripheries of the holders 34 and 36. Hence, the deformation of the shaft 38 is confined in the elastic deformation range based on the gaps 42. As a result, the shaft 38 is restored to its original position and, therefore, free fro an deformation permanently.

Further, the cylindrical portion 40a is located at the end of the weight 40 and remotest from the root of the shaft 38. Therefore, even a slight deformation of the shaft 38 is transformed to a noticeable displacement of the portion 40a.

1 0 It follows that the portion 40a is restricted by the inner peripheries of the holders 34 and 36 at the early stage of deformation, thereby reducing the deformation of the shaft 38.

An alternative embodiment of the present invention is shown in FIGS. SA and 5B. As shown, the motor,generally 30A, is identical with the motor 30 except that a tube 44 is substituted for the holders 34 and 36. Specifically, the holders 34 and 36 should only guarantee the gaps 42 between them and the cylindrical portion 40a of the weight 40. Hence, this embodiment has the tube 44, also guaranteeing the gaps 42, mounted on the casing 32 in place of the holders 34 and 36. In this configuration, the cylindrical portion 40a is also restricted by the inner periphery of the tube 44, preventing the shaft 38 from deforming.

0 7 FIGS. 6A-6C show another alternative embodiment of the present invention which is mounted on a portable apparatus. As shown, the motor, generally 3013, has a weight 40 formed with a cylindrical portion 40a. A holder 46 is formed integrally with (lie easing part 50 which cooperates with a counterpart 48 to constitute the casing of the apparatus. The holder 46 has a portion 46a which is provided with a height h at least greater than one half of the height of the motor casing 32. In this condition, the cylindrical portion 1 0 40a in rotation hits against and is restricted by the inner surfaces of the holder 46 and casing parts 48 and 50. As a result, the shaft 38 is prevented from deforming.

In the embodinients described above, the gaps 42 and the weight 40 are is deformed due to an portion 40a of (he weight 40 hits 36 and 46 and thereby restores the position. This prevents the motor from The cylindrical portion 40a, forming part of the weight 40, does not reduce the amount of vibration because the original eccentricity of the weight 40 is guaranteed by the other portion of the weight 40.

In summary, in accordance with the present invention, a vibration generating motor has an eccentric weight including a 2 5 cylindrical portion. A particular gap is formed betweenthe between the holders 3, 36 and 46 small. Hence, even when the shall 38 impact, (lie cylindrical against [fie holders 34, shaft 38 to its original becoming inoperable.

1 0 cylindrical portion and a holder. In this configuration, when an impact due to fall or similar cause acts on the motor, the deformation of a motor output shaft is confined in the elastic deformation range. This allows the diameter of the shaft to be reduced and thereby miniaturizes the motor. Because the weight is located the casing of the motor, the motor is easier to assemble and lower in cost than a motor having a weight inside its casing. The motor is, therefore, inexpensive, miniature and highly resistive to shocks and impacts.

Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope of the invention, as defined in the appended claims.

- 9 1

Claims

1 A structure of a motor for generating vibration, comprising:

a casing accommodating a body of said motor; an output shaft extending out from said casing and for transmitting rotation of said body; a weight mounted on said output shaft, and comprising an eccentric body portion and a non-eccentric cylindrical portion; and a holder holding said motor; 1 0 wherein a gap between said holder and said cylindrical portion is less than an elastic deformation range of said output shaft.

2. A structure as claimed in claim 1, wherein said holder is formed integrally with said casing.

3. A structure as claimed in claim 1, wherein said cylindrical portion is positioned at an end of said weight remote from said casing.

4. A structure as claimed in claim 1, wherein said weight is made of a material having a great specific gravity.

5. A structure as claimed in claim 1, further comprising a casing of a portable apparatus for mounting said motor, wherein said holder is formed integrally with said casing of said portable apparatus.

1 5 - 1 0 - 1

6. A vibration generating motor structure as claimed in claim 1, substantially as described herein with reference to Figs. 4A and 4B, Figs. SA, 5B, 6B and 6C, or Fig. 6A of the accompanying drawings.