SMALL ELECTRONIC APPARATUS EQUIPPED WITH GENERATOR

Abstract: A small electronic apparatus that transmits mechanical energy obtained by the turning or reciprocating motion of a rotary weight to a power generator rotor to produce electric energy so as to operate itself. The apparatus comprises a power transmission mechanism for accelerating the rotation of the rotary weight, a power generator rotor driven by the power transmission mechanism and a coil block for inducing voltage based on the rotation of the rotor, wherein at least one shock-absorbing spring is interposed between the rotary weight to the power generator rotor.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a small electronic apparatus equipped with a generator which converts mechanical energy obtained by the rotational or reciprocating motion of a rotary weight to electrical energy, as known from EP-A- 0 170 303, and especially to a small electronic apparatus equipped with a generator, which exhibits improved impact resistance in a mechanical power transmission mechanism in the generator and exhibits improved generating efficiency. Description of the Background Art An electronic wristwatch is one of a group of small electronic apparatuses in which mechanical energy obtained by rotary motion or reciprocating motion of a rotary weight is converted into electric energy, enabling the devices to be operated. In a generator of such an electronic wristwatch, there is a problem that when the rotary weight is hit by a strong impact caused by dropping the wristwatch or the like, support materials, gears, and pinion gears for the mechanical power transmission mechanism of the rotary weight is damaged or the ICs are broken. There have been methods disclosed, for example, in Japanese Patent Application Laid-open No. JP-A-63 128286/1988 aiming to avoid damages to the mechanical power transmission mechanism of the rotary weight to improve the impact resistance. Specifically, a device disclosed in said Japanese Patent Application Laid-open No. JP-A-63 128286/1988 comprises a slip device which transfers motive force to the power transmission mechanism by a frictional force. The slip device slips to avoid transfer of a strong impact load torque applied on the power transmission mechanism when a strong impact is applied on the rotary weight. Also, the rotational velocity transferred to the rotor is restrained by the slip action of the slip device to protect the charge control circuit from damages caused by a high voltage induced in a coil for a generator because of high rotation of a generator rotor due to an impact on the rotary eight. Almost the same method as in said Japanese Patent Application Laid-open No. JP-A-63 128286/1988 is disclosed in International Patent Application No. WO-A- 89/06833 and EP-A- 0 326 312. Also, as prior art, Figure 5 described in Japanese Patent Application Laid-open No. JP-A-030 91992/1991 shows the provision of a rotary weight itself provided with a spring structure which is resistant to an impact on the rotary weight. By this prior art, the effect of absorbing an impact torque in the direction along the rotation of the rotary weight can be expected. However, in the prior art of said Japanese Patent Application Laid-open No. JP-A-63 128286/1988 and said International Patent Application No. WO-A-89/06833 and EP-A- 0 326 312, in which the slip device is provided in the power transmission mechanism of the rotary weight, it is necessary to reduce the slip torque to less than the mechanical strength limit of tenons, gears, or the like. The slip torque must be designed to have a considerably small value taking safety into consideration. If the rotational force transferred to the power transmission mechanism of the rotary weight is higher than the slip torque, the slip device assembled in the power transmission mechanism slips to run idle with the rotation of the rotary weight. Therefore, the rotor does not follow the rotation, resulting in a reduction in generating efficiency. In the prior art shown in Figure 5 in Japanese Patent Application Laid-open No. JP-A-030 91992/1991, in which the rotary weight itself is provided with the spring structure, if it is intended to provide the rotary weight with an appropriate spring structure to prevent the power transmission mechanism from destructive impact, the stiffness of the rotary weight itself is reduced. When the rotary weight is subjected to a strong impact, it tends to be deformed. This invention has been achieved in view of this situation and has an object of providing a small electronic apparatus equipped with a generator having a high generating efficiency without slip, differing from the conventional power transmission mechanism. Another object of the present invention is to provide a small electronic apparatus provided with a generator which protects the power transmission mechanism from destructive impact, differring from the conventional power transmission mechanism, even if such destructive impact is applied to a rotary weight. Disclosure of the Invention The above objects can be attained in the present invention by a small electronic apparatus equipped with a generator which converts mechanical energy obtained by the rotational or reciprocating motion of a rotary weight to electrical energy, comprising: a power transmission mechanism for accelerating the obtained by the rotational or reciprocating motion of the rotary weight; a power generator rotor driven by the power transmission mechanism; and a coil block for inducing voltage based on the rotation of the power generator rotor, wherein at least one shock-absorbing spring is provided between the rotary weight and the power generator rotor. This structure reduces the impact transferred from the power transmission mechanism to the power generator rotor when a strong impact is applied to the rotary weight, because the shock-absorbing spring bends to absorb the rotating energy. Therefore, destruction of gears, their support materials, pinions, and the like of the power transmission mechanism is avoided and induction of high voltage in the generator coil can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an internal top plan view of a first embodiment of an electronic wristwatch. Figure 2 is an enlarged sectional view along the line A-A in Figure 1. Figure 3 is an enlarged sectional view along the line B-B in Figure 1. Figure 4 is an enlarged sectional and overlaid view along the lines C-C and D-D in Figure 1. Figure 5 is a top plan view of a rotary weight block corresponding to the first embodiment. Figure 6 is a sectional view along the line E-E in Figure 5. Figure 7 is a top plan view of a second embodiment of the rotary weight block of the present invention. Figure 8 is a sectional view along the line F-F in Figure 7. Figure 9 is a top plan view of a third embodiment of the rotary weight block of the present invention. Figure 10 is a sectional view along the line G-G in Figure 9. Figure 11 is a partly enlarged view showing fitting conditions between a weight pinion and a rotary weight and between the weight pinion and a shock-absorbing spring corresponding to the third embodiment. Figure 12 is a longitudinal section of the inside of a wristwatch provided with the rotary weight block corresponding to the third embodiment. Figure 13 is a top plan view of a fourth embodiment of the rotary weight block of the present invention. Figure 14 is a top plan view of a fifth embodiment of the rotary weight block of the present invention. Figure 15 is a sectional view along the line H-H in Figure 14. Figure 16 is a top plan view of a generator energy intermediate wheel showing the relation of the generator energy intermediate wheel to a shock-absorbing spring. Figure 17 is a sectional view along the line I-I in Figure 16. Figure 18 is a sectional view showing the inside of an electronic wristwatch using a sixth embodiment of the energy intermediate wheel. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS The present invention will now be explained in detail with reference to the drawings. In this embodiment, an example of an electronic wristwatch will be explained as the small electronic apparatus equipped with a generator. <First Embodiment> Figure 1 is an internal top plan view of a first embodiment of an electronic wristwatch, Figure 2 is an enlarged sectional view along the line A-A in Figure 1, Figure 3 is an enlarged sectional view along the line B-B in Figure 1, Figure 4 is an enlarged sectional and overlaid view along the lines C-C and D-D in Figure 1. This electronic wristwatch comprises a generator 1 for converting kinetic energy to electrical energy, storage cells 2, 3 acting as a secondary battery, a time-driving motor 4 rotated by a power source from the storage cells 2, 3, a train wheel part 5 for transferring the rotation of the motor 4 to a time display with a pointer (not shown), a winding stem 6 for revising the indicated time of the pointer, a circuit chip 7, a diode 8, a composite circuit 10 on which a crystal oscillator 9 and the like are mounted, and the like. The generator 1 is comprises a rotary weight block 11, an energy intermediate wheel 12 for a generator including an energy intermediate gear 12a for a generator, an energy intermediate pinion 12b, an energy intermediate pinion ring 12c, a generator rotor 13, a generator stator 14, and a generator coil block 15. Figure 5 is a top plan view of the rotary weight block 11 and Figure 6 is a sectional view along the line E-E in Figure 5. The rotary weight block 11 comprises a rotary weight 16, a weight pinion 17, and a spiral shock-absorbing spring 18. The above structure will be explained in more detail with reference to Figures 1-6. As shown in Figure 2, a pinion 17a of the weight pinion 17, a support 16a of the rotary weight 16, and the shock-absorbing spring 18 are disposed so as to form three layers in the center of the rotary weight 11. An engaging part 17b of the weight pinion 17 is inserted with a margin into a rotational center hole 16b. Also, the rotary weight 16 is supported with an appropriate clearance by and between a pinion top 17c of the weight pinion 17 and a bottom surface 18a of the shock-absorbing spring 18. Specifically, the rotary weight 16 is rotationally supported free from the weight pinion 17. Also, a spring center 18b of the shock-absorbing spring 18 is secured to the weight pinion 17. A spring edge 18c is secured in a pin hole 16c of the rotary weight 16 by a pin 19 in a rotationally free condition. The rotational motion of the rotary weight 16 is transferred to the weight pinion 17 via the shock-absorbing spring 18. By this structure, mechanical energy produced by the rotational motion or reciprocal motion of the rotary weight 16 is transferred to the weight pinion 17 via the shock-absorbing spring 18 and further transferred from the weight pinion 17 to the generator rotor 13 via the generator energy intermediate wheel 12 by which the motion is accelerated. Specifically, the generator rotor 13 is rotated at a high speed to convert mechanical energy to electric energy. Here, the spring constant of the shock-absorbing spring is designed as follows: In a case of the rotational force of the rotary weight under ordinary carrying conditions of an electronic wristwatch which is worn on the human wrist, the spring constant is designed so that the shock-absorbing spring 18 is only slightly deformed. In this case, the rotary weight 16 and the weight pinion 17 rotate almost in unity. On the other hand, in the case where the rotary weight is rapidly rotated caused by some reason such as dropping the wristwatch, violent shaking of the hand, or the like, the shock-absorbing spring 18 bends to absorb the rotational energy so that the impact force of the rotary weight is not directly transferred to the weight pinion 17 and the power transmission mechanism succeeding the weight pinion 17. Incidentally, in the above embodiment, an example of an integrated rotary weight 16 is illustrated. However, the rotary weight may be a composite of two or more elements. Also, only one storage cell may be used as the secondary battery. <Experimental Example> If the spring force of the shock-absorbing spring 18 is too strong, the bending angle of the spring becomes small and the spring cannot sufficiently absorb the rotational energy when receiving the impact. On the other hand, if the spring force is too weak, the bending angle of the spring becomes large when receiving the impact. Therefore, the rotational velocity transferred to the power transmission mechanism becomes lower relative to the rotational velocity of the rotary weight, leading to a reduction in generating efficiency. Therefore, the shock-absorbing spring 18 is designed with a shape as illustrated below. When the accelerating rate of the train wheel between the weight pinion 17 and the generator rotor 13 is designed in a range of from 60 to 100, the thickness of the plane spring is in a range of from 0.2 to 0.3 mm so that it has no influence on the thickness of a watch movement. Also, the width of the spring is in a range of from 0.5 to 1.0 mm and the number of turns of the spiral portion is in a range of from 1.0 to 3.0. Specifically, the spring is not designed so that an edge 18c of the spring extends to the outer periphery of the rotary weight 16. Further, the spring constant (spring torque to a bending angle) of the shock-absorbing spring 18 is designed in a range of from 5 gr·cm/degree to 30 gr·cm/degree approximately. It has been confirmed that the shock-absorbing spring 18 designed in the above manner has excellent impact resistance without any fatigue, exhibiting high generating efficiency. <Second Embodiment> Figure 7 is a top plan view of a second embodiment of the rotary weight block of the present invention and Figure 8 is a sectional view along the line F-F in Figure 7. An rotary weight block 20 comprises a rotary weight 21, a weight pinion 22, and a shock-absorbing spring 23. The fitting conditions between the rotary weight 21 and the weight pinion 22 and between a shock-absorbing spring 23 and the weight pinion 22 are the same as those in the first embodiment. The shock-absorbing spring 23 includes a pair of spring parts 23b, 23c of an arm shape which extend forward to both sides from a step part 23a integrally extending from the weight pinion 22. Respective edges 23d, 23e of the spring parts 23b, 23c directly contact the linear side surfaces 21a, 21b of the rotary weight 21. The spring parts 23b, 23c bend to absorb rotational energy when impact torque is applied to the rotary weight 21. The spring parts 23d, 23e have a curved shape to directly contact the side surfaces 21a, 21b of the rotary weight 21 and to smoothly slide on these side surfaces 21a, 21b when the spring parts 23b, 23c bend. By this structure, it is not necessary to provide the pin 19 used in the rotary weight block 11. Also, it is advantageous for realizing a thin watch since the sectional heights of the spring parts 23b, 23c are the same as that of the rotary weight 21. <Third Embodiment> Figure 9 is a top plan view of a third embodiment of the rotary weight block of the present invention; Figure 10 is a sectional view along the line G-G in Figure 9; Figure 11 is a partly enlarged view showing the fitting conditions between a weight pinion and a rotary weight and between the weight pinion and a shock-absorbing spring corresponding to the third embodiment; and Figure 12 is a longitudinal section of the inside of a wristwatch provided with the rotary weight block corresponding to the third embodiment. An rotary weight block 30 in the third embodiment comprises a rotary weight 31, a pinion body 32 which is an outer ring of a bearing including the outer ring and an inner ring, a weight pinion 33, and a shock-absorbing spring 34. Here, the center of the rotary weight 31 is secured to the pinion body 32 and, as shown in Figure 11, the height of the rotary weight 31 is defined by a shoulder part 32a of the pinion body 32. The rotary weight 31 is firmly secured to the pinion body 32 in this manner so that the rotary weight 31 does not rotate in the longitudinal direction when the rotary weight 31 is rotated, allowing the rotary weight 31 to rotate smoothly. The weight pinion 33 is marginally engaged with the outer periphery of the pinion body 32, having an appropriate clearance from an accession part 32b of the pinion body 32 and the rotary weight 31. Therefore, the motion of the pinion body 32 corresponding to the rotational motion and reciprocative motion of the rotary weight 31 is not directly transferred to the weight pinion 33. The shock-absorbing spring 34 is disposed under the rotary weight 31, having a clearance from the rotary weight 31. The center of the spring 34 is secured to the outer periphery of the upper portion of the weight pinion 33, and the spring 34 works in unity with the weight pinion 33. A pair of arms 34a, 34b of the shock-absorbing spring 34 are considerably bent in these central portions so as to project from the lower portion of the rotary weight 31 outward from a linear side surface 31a of the rotary weight 31. Also, the ends of the arms 34a, 34b projecting from the linear side surface 31a are bent to form almost a V shape. The respective ends 34c, 34d of the arms 34a, 34b of the shock-absorbing spring 34 are bent upward to form a key shape. Because of these shapes for the pair of arms 34a, 34b of the shock-absorbing spring 34, the ends 34c, 34d with a key shape directly contact the linear side surface 31a of the rotary weight 31, applying appropriate pressure to the linear side surface 31a. In the rotary weight block 30 of the third embodiment produced in this manner, even if the rotary weight is rotated in either the left or right direction, the rotational energy is transferred to the weight pinion 33 via either of the pair of arms 34a, 34b of the shock-absorbing spring 34. Thus, the weight pinion 33, rotary weight 31, and the shock-absorbing spring 34 are rotated in unity. Specifically, mechanical energy obtained by the rotational or reciprocative motion of the rotary weight 31 is transferred to the weight pinion 33 via the shock-absorbing spring 34. The mechanical energy is then transferred to the generator rotor 13 via the generator energy intermediate wheel 12, by which the rotational velocity is accelerated. Specifically, the generator rotor 13 is rotated at a high speed to convert mechanical energy to electrical energy. The spring constant of the shock-absorbing spring 34 is so designed that, in the case of the rotational force of the rotary weight in ordinary carrying conditions of the electronic wristwatch worn on the human wrist, the shock-absorbing spring 34 is only slightly deformed. On the other hand, in the case where the rotary weight 31 is rapidly rotated caused for some reason, the arms 34a, 34b for accepting rotational force from the shock-absorbing spring 34 bend to absorb the rotational energy so that the impact force of the rotary weight 31 is not directly transferred to the weight pinion 33 and the power transmission mechanism succeeding the weight pinion 33. <Fourth Embodiment> Figure 13 is a top plan view of a fourth embodiment of the rotary weight block of the present invention. A rotary weight block 40 of the fourth embodiment comprises a rotary weight 41, a pinion body 42, a weight pinion 43, and a shock-absorbing spring 44. The fitting conditions between the rotary weight 41 and the pinion body 42 and between the weight pinion 43 and a shock-absorbing spring 44 are the same as those in the third embodiment. The shock-absorbing spring 44 is provided with a pair of arms 44a, 44b projecting from the opposite sides of the center thereof at an angle of 180 degrees. The respective ends 44c, 44d of the arms 44a, 44b are bent upward to form a key shape. On the pair of arms 44a, 44b, the ends 44c, 44d of a key shape directly contact the linear side surface 41a of the rotary weight 41, applying appropriate pressure to the linear side surface 41a. The rotary weight block of the fourth embodiment acts similarly to the rotary weight block of the third embodiment. <Fifth Embodiment> Figure 14 is a top plan view of a fifth embodiment of the rotary weight block of the present invention and Figure 15 is a sectional view along the line H-H in Figure 14. In the rotary weight block 50 of the fifth embodiment, the fitting conditions between the rotary weight 51 and the pinion body 52, and between the weight pinion 53 and a shock-absorbing spring 54, are the same as those in the rotary weight block of the third embodiment. The shock-absorbing spring 54 is in the form of a spiral. The center of the spring 54 is integrally secured to the weight pinion 53 and an end 54a of the spring 54 is inserted into a rectangular opening 51a under rotation-free and movement-free conditions using a pin 55. Therefore, in the rotary weight block of this embodiment, the rotation of the rotary weight 51 is transferred to the weight pinion 53 via the shock-absorbing spring 54. In addition, when a large impact is applied to the rotary weight 51 caused by dropping the electronic wristwatch or the like and thereby causing the rotary weight 51 to rapidly rotate, the shock-absorbing spring 54 bends and the end 54a of the spring 54 moves in the rectangular opening 51a to absorb the impact torque. <Sixth Embodiment> In the sixth embodiment, a shock-absorbing spring is installed under a generator energy intermediate wheel. Figure 16 is a top plan view of a generator energy intermediate wheel showing the relation of the generator energy intermediate wheel to a shock-absorbing spring; Figure 17 is a sectional view along the line I-I in Figure 16; and Figure 18 is a sectional view showing the inside of an electronic wristwatch using an energy intermediate wheel corresponding to the sixth embodiment. As shown in Figure 18, a rotary weight block 60 comprises a rotary weight 61 and a weight pinion 62, which are integrally joined and rotated in unity. The generator energy intermediate wheel 64 includes a generator energy intermediate gear 64a, an energy intermediate pinion 64b which engages the weight pinion 62, and an energy intermediate pinion ring 64c. The generator energy intermediate wheel 64 engages a rotor pinion 68a of a generator rotor 68. Also, a shock-absorbing spring 63 is installed under the generator energy intermediate gear 64a. Specifically, the generator energy intermediate gear 64a is supported with an appropriate clearance by and between a center 63a of the shock-absorbing spring and a haft part 64d of the energy intermediate pinion ring 64c integrally formed with the energy intermediate pinion 64b. The energy intermediate pinion ring 64c is inserted into a center hole 65 of the generator energy intermediate gear 64a under rotation-free conditions. Also, a pin 67 is inserted into a small hole 66 of the generator energy intermediate gear 64a under the rotation-free conditions and secured to an end 63b of the shock-absorbing spring 63. Therefore, the rotation of the rotary weight 61 is transferred to the energy intermediate pinion 64b via the weight pinion 62. The rotation is then transferred from the energy intermediate pinion 64b to the generator energy intermediate gear 64a via the shock-absorbing spring 63. The rotation is further transferred to the generator rotor 68 via the rotor pinion 68a. When the rotary weight 61 is rapidly rotated caused for some reason such as dropping the wristwatch, violent movement of the hand, or the like, the spring 63 united with the generator energy intermediate wheel 64 bends to absorb the rotational energy. In the present invention, a shock-absorbing spring may be arranged at some positions between the rotary weight and the weight pinion. Also, the generator energy intermediate wheel may be provided with a shock-absorbing spring and plural shock-absorbing springs may be arranged between the rotary weight and the power generator rotor to further improve the impact resistance. INDUSTRIAL APPLICABILITY OF THE INVENTION As is clear from the above illustrations, the small electronic apparatus equipped with a generator according to the present invention can be utilized for a variety of small electronic apparatuses capable of being carried on the arm or the body, such as an electronic wristwatch, a carrying-pager, or a passometer.

Claims: A small electronic apparatus equipped with a generator which converts mechanical energy obtained by the rotational or reciprocating motion of a rotary weight to electrical energy, comprising: a power transmission mechanism for accelerating the rotational or reciprocating motion of the rotary weight; a power generator rotor driven by the power transmission mechanism; and a generator coil block for generating induction voltage based on the operation of the power generator rotor, characterised in that at least one shock-absorbing spring is provided between the rotary weight and the power generator rotor. The small electronic apparatus equipped with a generator according to claim 1, wherein the power transmission mechanism includes a weight pinion and a generator energy intermediate wheel, the rotary weight being installed on the weight pinion under rotation-free conditions, the center of the shock-absorbing spring being secured to the weight pinion, the end of the spring being secured to the rotary weight, and the rotation of the rotary weight being transferred to the weight pinion via the shock-absorbing spring. The small electronic apparatus equipped with a generator according to claim 1, wherein the power transmission mechanism includes a pinion body, a weight pinion and a generator energy intermediate wheel, the rotary weight being secured to the pinion body, the weight pinion being installed on the outer periphery of the pinion body under rotation-free conditions, the center of the shock-absorbing spring being secured to the weight pinion, the end of the spring being secured to the rotary weight, and the rotation of the rotary weight being transferred to the weight pinion via the shock-absorbing spring. The small electronic apparatus equipped with a generator according to claim 1, 2, or 3, wherein the power transmission mechanism includes a weight pinion and a generator energy intermediate wheel which is provided with a generator energy intermediate gear and an energy intermediate pinion for transferring the force from the weight pinion, the generator energy intermediate gear being installed on the energy intermediate pinion under rotation-free conditions, the center of the shock-absorbing spring being secured to the intermediate pinion, the end of the spring being secured to the generator energy intermediate gear, and the rotation of the rotary weight being transferred to the generator energy intermediate gear via the shock-absorbing spring. The small electronic apparatus equipped with a generator according to claim 2, 3, or 4, wherein the shock-absorbing spring is spiral in shape, the end of the spring and the rotary weight or the generator energy intermediate gear are secured by a pin under rotation-free conditions. The small electronic apparatus equipped with a generator according to claim 2, 3, or 4, wherein the shock-absorbing spring is provided with an arm projecting from the center thereof, the end of the arm being directly contacted to the side edge of the rotary weight to be secured.

Inventors: ENOMOTO HIROO, HANAOKA TADASHI, MIYASAKA KENJI, SUZUKI NORITOSHI, ENOMOTO, HIROO, HANAOKA, TADASHI, MIYASAKA, KENJI, SUZUKI, NORITOSHI, ENOMOTO, Hiroo, Citizen Watch Co., Ltd., HANAOKA, Tadashi, Citizen Watch Co., Ltd., MIYASAKA, Kenji, Citizen Watch Co., Ltd., SUZUKI, Noritoshi, Citizen Watch Co., Ltd.
Applicants: CITIZEN WATCH CO LTD, CITIZEN WATCH CO., LTD.
Application year: 1996
Main classification: G04C10
IPC codes: G04C10