MXPA98002537A - Electric scraper - Google Patents

Abstract

The present invention relates to electric razor equipped with a simple electric motor, which includes external blades which are driven by the electric motor, and internal blades which are installed in combination with the external blades and driven rotetionally by the electric motor; the shaver is provided with a speed reduction mechanism constructed from a planetary gear assembly installed between a motor shaft gear, attached to an output shaft of the electric motor and gears installed on the external blades and where the reduction mechanism of The speed comprises: a plurality of planetary gear assemblies, each consisting of an internal central planetary gear, a plurality of planetary gears which are rotatably provided on a protractor and which engage the internal center gear, and an external central gear which is disposed in a center of the plurality of eng planetary forces in order to couple with each of the planetary gears, and wherein the plurality of planetary gear assemblies are provided in multiple stages, in internal central gear is formed into a single continuous cylindrical body to be commonly used with planetary gears , and one of the planetary gear assemblies is engaged with the outer center gear of another adjacent planetary gear assembly in a portion of the center of rotation of the planetary gear assembly carrier adjacent

Description

ELECTRIC SCRAPER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric shaver and more particularly to an electric shaver of the rotating type. 2. Prior Art Electric shavers, especially electric shavers of the rotating type; they usually include external cutters and internal cutters; and the internal cutters are rotated on the hidden surfaces of the external cutters and cut the hair such as hair on the head, sideburns, etc., (only called "hair"), which are introduced through the slots (openings of hair entry) formed in the internal cutters, by means of a shear force that is generated by the rotating internal cutters and stationary external cutters.

In electric shavers currently marketed, as seen from the foregoing, only the internal cutters, which are provided within the head part of the body of the shaver, are rotated by an electric motor installed within the shaver housing; and the external cutters, which are provided inside the shaver head, are not rotated. When these shavings are used, it is necessary that the hair be introduced into the hair entry slots formed in the external cutters, - consequently, the person using the shaver, needs to constantly move the head of the shaver on the surface of the shaver. the skin while holding the shaper housing with one hand. However, such constant movement of the shaver during shaving while holding with one hand for a period of several minutes, up to ten or more minutes causes fatigue of the arm mus, and therefore pain. In view of these problems, an electric razor including rotating external cutters for gently moving the hair into the hair entry slots has been proposed as described in the Pre-Examination Publication of the Japanese Patent Application (Kokai) No. H 7-16360. However, this electric shaver uses a plurality of electric motors as driving sources to rotate the outer cutter and the internal cutter. Therefore, it is difficult to build a compact electric shaver. In addition, since the external cutter is similar to the internal cutter, attached directly to the output shaft of an electric motor, the rotational speed is generally high, and this causes the skin to be scraped and injured. In addition, the external cutters of the electric shavers make direct contact with the skin and are therefore subject to the resistance of the skin. Therefore, in order to directly drive such external cutters, an electric motor of high torque is required. However, such high torque electric motors are generally large and therefore contradict the compact character of the electric shaver. Likewise, high-torque electric motors are more expensive.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, it is a general object of the present invention to solve the problems with electric razors of the prior art. The main object of the present invention is to provide an electric shaver which includes external and internal rotary cutters, with rotational speed of the external cutters being reduced and the overall size being compact. The above object is achieved by a unique structure of a rotary shaver of the present invention that includes an individual electric motor, external cutters rotated by the electric motor, and internal cutters installed in combination with the external cutters and rotated by the electric motor, and the shaver is further provided with a speed reduction mechanism constructed from a planetary gear assembly that is installed between a motor arrow gear attached to the output shaft of the electric motor and the gears attached to the external cutters. In the structure described above, the speed reduction mechanism in the form of a rotating gear assembly is employed as a mechanism that reduces the rotational speed of the internal cutters; consequently, the electric shaver can be made more compact compared to shavers using straight gear combinations as a speed reduction mechanism. In addition, the speed reduction mechanism comprises a plurality of planetary gear assemblies, and each consists of an internal planetary gear, a plurality of planetary gears which are rotatably mounted on a cutter and which engage with the internal planetary gear, and a external planetary gear which is placed in the center of a plurality of planetary gears and which engages with the planetary gears; and those planetary gear mounts are positioned to be one on top of the other or stacked, in multiple stages. In addition, the internal planetary gears of each of the planetary gear assemblies are formed on an internal surface of an individual cylindrical body to be used in a common manner with the external planetary gears. In addition, one of the planetary gear assemblies is intermeshed with the outer planetary gear of another adjacent planetary gear assembly at the center of the cutter rotation of the planetary gear assemblies. In other words, in this speed reduction mechanism, a plurality of planetary gear assemblies are placed in multiple stages to obtain a large speed reduction ratio; and at the same time, the internal planetary gears are formed in an individual cylindrical body. Therefore, the same speed reduction mechanism can be compact. In addition, the motor arrow gear coupled to the motor output shaft is used as the external planetary gear of the first stage planetary gear assembly (between the planetary gear assemblies provided in multiple stages); consequently, the center of rotation of the output shaft of the motor and the center of rotation of the speed reduction mechanism are aligned to be on the same straight line or axis. As a result, it is possible to design the overall external diameter of the engine speed reduction mechanism to be small, so that the electric shaver can be made much more compact.BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partially cutaway side view of an embodiment in the electric shaver of the present invention; Figure 2 illustrates the internal construction of the head section and the head frame of the shaver of Figure 1; Figure 2 is a view taken along line 2-2 in Figure 3; Figure 3 is a schematic illustration showing the relationship between the output gear-reduction gear and the annular gears for the external cutters seen in the direction of line 3-3 in Figure 2; Figure 4 is an exploded illustration of the internal construction of the speed reduction mechanism employed in the present invention; and Figure 5 is a schematic illustration showing the relationship between the speed reduction mechanism and the internal cutter driving arrows seen in the direction of the line. -5 in Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED MODAL DADES A preferred embodiment of the electric shaver of the present invention will be described in detail with reference to the accompanying drawings. The shaver 10 shown in Figure 1 includes three external and internal cutters (or three pairs of external and internal cutters) placed in an inverted equilateral triangle shape as best seen in Figure 3. The present invention is, however, applicable to shavers that include a set or two sets of external and internal cutters. The electric shaver 10 in this embodiment generally comprises a synthetic resin housing 16, an electric motor 18, a battery unit 20, a connector 22 and a switch 24. The housing 16 has a head portion 16a in the upper portion thereof , so that the external cutting units 12 are installed therein in a partially exposed manner and inside the head part 16a, there is provided a driving mechanism 14 for activating the external cutting units 12. The electric motor 18 is installed in the lower portion of the head portion 16a den of the housing 16 for operating the drive 14. The battery unit 20 is installed within the lower area of the housing 1-6 - and supplies electrical power to the electric motor 18. The connector 22 is installed at the lower end of the housing 16 to supply a charging current to the battery 20 from the outside of the shaver. The slide-type (or any other type) switch 24 is mounted on the external surface (or front side) of the housing 16 to be used to turn on and off the power supply from the battery 20 to the electric motor 18. The construction of the inside of the head part 16a is described in detail with reference to Figure 2. The upper end of the head part 16a of the housing 16 is open and covered by a detachable head frame 26; and a mounting plate 28 and a driving arrow support 30 are installed in the head portion 16a. The head frame 26 has a cutter attachment frame 34 which is removably fitted to the head frame 26 by a connecting screw 32 so that it is positioned within the head frame 26. Therefore, the connecting frame Decutter 34 supports the external cutting units 12 between this cutter attachment frame 34 and the head frame 26, so that the external cutting units 12 can be rotated. Each external cutting unit 12 is constructed from an external cutter 36 and an external cutter holder 38 and includes an internal cutter 40 installed therein. In addition, the head frame 26 is formed with first circular openings 42 which engage the shape of the external cutters 36 by a number equal to the number of the external cutters 36 (three, in this embodiment), and the upper surfaces of the external cutters. 36 of the external cutting units 12, held as described above, protrude to the outside from the outer surface of the head frame 26 as best seen in Figure 1. The construction of the external cutting units 12 will now be described in detail. Three external cutting units 12 are employed in this embodiment and have the same structures, - and each one comprises the external cutter -36 and the cutter holder 38 - with an internal cutter 40. Each external cutter 36 has a flange 36a formed in the circumferential portion thereof. Each outer cutter holder 38 is in a tubular shape and has a larger diameter portion 38a formed in the upper end (in Figure 2) thereof and a smaller diameter portion 38b formed in the lower end thereof (in Figure 2). The lower portion of the corresponding external cutter 36 is inserted into the larger diameter portion 38a of the external cutter support 38. A hook portion 38b is formed by inwardly restricting the edge portion of the larger diameter portion. 38a and engages the flange 36a of the external cutter 36 so that the external cutter 36 and the external cutter holder 38 are integrally connected. In addition, an annular gear 44 which couples with the speed reduction output gear of the speed reduction mechanism (which is described below) is attached to the outer circumference of the smaller diameter portion 38c of the external cutter holder 38. The annular gear 44 is formed from, for example, a synthetic resin material and is fixedly secured on the outer circumference of the smaller diameter portion 38c of the external cutter holder 38. Alternatively, the annular gear 44 it can be formed integrally on the outer circumferential surface of the smaller diameter portion 38c of the cutter support and bracket 38. In addition, the respective outer cutter units 12 are held between the head frame 26 and the connecting frame 34, such so that the external cutting units 12 can be rotated. This rotatable arrangement is obtained by inserting the upper portions of the external cutters 36 (which have the hair entry slots not shown) formed on the upper surfaces and the lateral surfaces) within the first opening 42 formed in the head frame 26 and inserting the smaller diameter portions 38c on which the annular gears 44 are installed within the second openings 46 formed in the cutter attachment frame 34. The second openings 46 are formed so that they are equal in number to the first openings 42 and correspond positionally to the first openings 42. The internal diameter of the second openings 46 is smaller than the outer diameter of the larger diameter portions 38a of the external cutter supports 38, so that the external cutter units 12 are prevented from sliding out of the cutter attachment frame 34. In addition, as shown in Figure 3, n speed reduction output gear 48, which is in the output gear of the speed reduction mechanism (desc below) is installed in the center which is defined by three annular gears 44 of the external cutter units placed in the center. iangularly e 12 so that the speed reduction output gear 48 engages with the respective annular gears 44. The driving mechanism 14 will be described below with reference to Figure 2. The driving arrow support 30 is formed with three ( 3) arrow holes 52 so as to correspond to the three external cutting units 12, and three (3) driving arrows 50 (only two (2) shown in Figure 2) to rotate the internal cutters 40 that are rotatably inserted within -the arrow insertion holes 52. These insert holes 52 are placed in a reverse triangle shape, and a mounting hole 56 is formed in the central area thereof, surrounded by those three (3) arrow insertion holes 52 so that a speed reduction mechanism 54 that is of a cylindrical shape is inserted into the hole of assembly 56. The driving arrows 50 are provided respectively with coupling tongues 50a. Each of the coupling tongue portions 50a is formed at one end (upper end in Figure 2) of each driving shaft 50 to be located closer to the external cutting units 12. The tongue of the driving arrows 50 is inserted inside the coupling holes 40a formed in the internal cutters 40, so that the rotational force of the driving arrows 50 can be transmitted to the internal cutters 40. The driving arrows 50 are further provided with flanges 50b. Each of the tabs 50b is formed at another end (lower end in Figure 2) of each driving shaft 50 and located closer to the mounting plate 28. The tabs 50b of the driving arrows 50 are inserted into hollow masses 68 (described below). The electric motor 18 is mounted within the concealed surface of the mounting plate 28 so that the output shaft 18a of the motor 18 enters the area of the mounting plate 28 and the drive shaft holder 30, and the drive gear motor shaft 60 is coupled to output shaft 18a of motor 18. Motor shaft gear 60 is formed at the upper end thereof (or upper end thereof in Figure 2) with an end gear section 60a that it is used as an external planetary gear of the planetary gear assembly of the first stage 58 of the speed reduction mechanism 54; and further, the motor shaft gear 60 is formed at an intermediate portion vertically therefrom (in FIG. 2) with a base gear section 60b that is circumferentially formed on the motor shaft gear 60 and engages with the gears internal cutter drivers 66 attached to three transmission arrows 64 (described above).

In addition, three arrow support holes 62 are formed in the mounting plate 28 to match the driving arrow support 30. Those three holes of arrow supports 62 (only '2 are shown) are concentric with the three insertion holes of the arrow. arrow 52 that are open in the driving arrow support 30; and the respective transmission arrows 64 are inserted into these arrow support holes 62, so that the transmission arrows 64 are parallel to the output arrows 18a of the motor 18 and are rotatable about their own axes in the orifices. arrow bracket 62. Each drive shaft 64 has an internal cutter drive gear 66 that engages circumferentially with the base gear section 60b of the motor shaft gear 60; and a hollow mass 68 which has a cylindrical cavity area 68a opening to the driving shaft holder 30, is attached to the tip end (or the upper end in Figure 2) of each transmission shaft 64. The ends of tip (lower ends in Figure 2) of the respective driving arrows 50 on which the flanges 50b are formed, are inserted into the cavity areas 68a of the hollow masses 68 and - the driving arrows 50 are therefore connected to the hollow masses 68. Ribs (not shown) that travel along the direction of the transmission arrows 64 (or in a vertical direction in Figure 2) are formed on the inner wall surfaces of the hollow masses 68, and the cuts (not shown) are formed in the flanges 50b so that the respective driving arrows 50 are inserted into the cavity areas 68a of the hollow masses 68 and the ribs and cuts are engaged. Therefore, each drive shaft 50 can move in the direction of the axis of the transmission shaft 64 relative to the corresponding hollow mass 68; and when the hollow masses 68 are rotated by the motor 18 by means of the internal cutter driving gears 66, the driving arrows 50 are rotated by the hollow masses 68. A coil spring 70 is installed within the cavity area 68a of the dough hollow 68 so that the corresponding driving shaft 50 is constantly driven towards the external cutting unit 12 relative to the hollow mass 68.

In other words, in the above embodiment, a tubular portion 68b is formed in the center of the interior of the cavity area 68a of each hollow mass 68, and the tip end (bottom) of the corresponding transmission arrow 64, is inserted inside. of the tubular portion 68b; in addition, a second cavity area 50c opening towards the hollow mass 68 is formed in the driving shaft 50 so that the tubular portion 68b is inserted into the second cavity area 50c. In addition, the coil spring 70 is loosely fitted on the tubular portion 68b of the hollow mass 68 and positioned within the second cavity area 50c. Next, the speed reduction mechanism 54 will be described with reference to Figures 4 and 5. In the electric shaver 10 of the present invention, the internal cutters 40 are rotated (at a high speed) and the external cutters 36 are rotated. so that the hair is carried directly into the open hair entry slots in the external cutters 36. Furthermore, in order to allow sufficient rotary pulse of the external cutters without causing skin abrasion injuries, which are caused by the high-speed rotation of the external cutters, and without using a high-torque electric motor, a speed reduction mechanism 54 is installed in the present invention between the electric motor 18 and the annular gears 44 provided on the external cutters 36. In addition, the speed reduction mechanism 54 is constructed from the assembly of planetary gears in order to reduce The size of the speed reduction mechanism 54 is minimized while a large speed reduction ratio is obtained. More specifically, as shown in Figure 2 and in detail in Figure 4, the speed reduction mechanism 54 is constructed from a plurality (three in that embodiment) of planetary gear assembly 72, 74 and 76 that are installed in parallel to one another, or in a stacked manner adjacent to each other in multiple stages in a vertical direction in Figures 2 and 4. Each of those planetary gear assemblies 72, 74 and 76 will be described below in that order.

A first-stage planetary gear assembly 72 is placed closer to the electric motor 18 and consists of a cylindrical internal planetary gear 72a, a plurality of (or three) planetary gears 72c that are rotatably provided on the concealed surface of a first carrier disk 72b and coupling with the internal planetary gear 72a, and an external planetary gear which is in the end gear section 60a (of the motor arrow gear 60) and placed centrally to be surrounded by a plurality of planetary gears 72c and further it couples with the respective planetary gears 72c. In the present embodiment, the inner planetary gear 72a has an axial length corresponding to the combined thicknesses of the three stacked planetary gear assemblies 72, 74 and 76, so that the internal planetary gear 72a acts as an internal planetary gear for all planetary gear assemblies 72, 74 and 76. The second planetary gear assembly 74 consists of an internal planetary gear 72a described above, a plurality of (three) planetary gears 74c which are rotatably provided on the hidden surface of a second carrier disk 74b, and an external planetary gear 74d which is placed in the central area surrounded by the plurality of planetary gears 74c and couples with the respective planet gears 74c. The planetary gear 74d is attached to the upper surface of the first carrier disk 72b at the center of rotation. The third planetary gear assembly 76 consists of the above-described internal planetary gear 72a, a plurality (of three) planet gears 76c that are rotatably provided on the concealed surface of a third carrier disk 76b and an external planetary gear 76d that is placed on the central area surrounded by the plurality of planetary gears 76c and coupled with respective planetary gears 76c. The outer planetary gear 76d is attached to the upper surface of the second carrier 74b to be at the center of rotation thereof. In other words, the constituent elements of the respective planetary gear mounts 72, 74 and 76 are positioned within the internal planetary gear 72a which is a single continuous cylindrical body commonly used with the three planetary gear mounts 72, 74 and 76; and those planetary gear mounts 72, 74 and 76 are positioned such that the outer planetary gear (74d, 76d) of each planetary gear assembly is provided on the carrier disk (72b, 74b) of a preceding planetary gear assembly ( lower) to be placed in the center of rotation of the carrier discs. It is observed from the foregoing, in the present invention, an individual internal planetary gear 72a which is used in common manner with the respective planetary gear assemblies 72, 74 and 76 thus being as an integral body having the same diameter external and the plurality of planetary gear mounts 72, 74 and 76 are provided one over the other in multiple stages (or placed vertically in Figure 4). Accordingly, the volume of the speed reduction mechanism 54 is more compact than in cases when the speed reduction mechanism is constructed, placing a plurality of straight gears in a substantially horizontal manner. Therefore, the electric shaver 10 can be made more compact. Also, in a preferred construction, gears 76c, 74c and 72c, gears 74d and 76d and disks 72b and 74b would be of the same size to reduce costs. The component elements of the three planetary gear assemblies 72, 74 and 76 are prevented from sliding out of the tubular internal planetary gear 72a by means of first and second covers 78f and 78s which are attached to both openings (at the upper and lower end) in Figure 4) of the internal planetary gear 72a. The speed reduction mechanism thus obtained 54, is attached to the arrow support 30 by inserting the internal planetary gear 72a into the mounting hole 56 of the bracket 30. In addition, the speed reduction output gear 48 described above is attached, as an output gear of the gear reduction mechanism. speed 54 to the upper surface of the third carrier disk 76b of the planetary gear assembly of the highest stage 76 to be in the position of the center of rotation. The speed reduction output gear 48 protrudes from a central hole 78a of the first cover 78f and is placed centrally surrounded by the three annular gears 44 attached to the respective external cutting units 12, so that the output gear of Speed reduction 48 is interdetermined with the respective annular gears 44. Likewise, the motor output shaft 60 having the end gear section 60a (used as the external planetary gear for the first stage gear assembly 72) is inserted into a central hole 78a of the second cover 78s of the internal planetary gear 72a. With the above arrangement, the respective transmission arrows 64, the driving arrows 50 and the cutting units 12 are, as best shown in Figure 2, placed on the same rotational axes that are parallel to the output shaft 18a of the electric motor 18. On the other hand, the center of the speed reduction mechanism 54 obtained by placing three planetary gear assemblies 72, 74 and 76 one on the other in multiple stages is placed on the same rotational axis as the output arrow 18a of the electric motor 18.

The operation of the modality described above will now be described. First, when the slide switch 24 is operated, the electric current is supplied to the electric motor 18 from the battery 20 and the electric motor 18 is driven so as to rotate the output arrow 18a, thereby rotating the arrow gear of motor 60 coupled to the output shaft 18a. As a result, the external units 12 and the internal cutters 40 are rotationally driven. The rotary pulse of the external cutting units 12 and the internal cutters 40 will be described below. First, the rotation of the internal cutters will be described. When the motor shaft gear 60 is rotated (the direction of rotation of the gear 60 is referred to as X), the three internal cutter drive gears 66 engage the base gear section 60b of the motor shaft gear 60, rotate respectively in the direction Y, which is opposite to the direction of rotation X of the motor shaft gear 60, so that the three hollow masses 68 attached to the tip ends of the respective transmission arrows 64, also rotate in the same direction Y. Accordingly, the three driving arrows 50 connected to the hollow masses 68 also rotate in the same direction Y, so that the internal cutters 40 placed within the respective external cutting units 12 rotate in the Y direction which is opposite of the direction of rotation X of the motor shaft gear 60. In this case, when Z2 is the number of teeth on the base gear section 60B and Z3 is the number number of teeth on the inner cutter drive gears 66, the speed reduction ratio is Z3 / Z2. If, for example, Z2 = 16 and Z3 = 36, the speed reduction ratio Ri (between the internal cutter drive gears 66 and the base gear section 60b) = 36/16 = 2.25. Next, the rotation of the external cutters 36 will be described. When the motor shaft gear 60 is rotated in the X direction as described above, the rotational force is transmitted to the speed reduction mechanism 54 from the end gear ejection 60a of the shaft gear 60. The transmission of The rotational force of the speed reduction mechanism 54 is achieved as follows: (1) First, the planetary gears 72c of the first planetary gear assembly 72 which are coupled with the end gear section 60a make a circular motion along the the inner circumference of the inner planetary gear 72a in the X direction which is the same as the end gear section 60a (as long as the planetary gears 72c rotate by themselves). As a result, the carrier 72b rotates (revolutionizes) in the X direction around the end gear section 60a. (2) In the second planetary gear assembly 74, as in the first planetary gear assembly 72, the outer planetary gear 74d attached to the carrier 72b is rotated in the same X direction according to the end gear section 60a, - and so both, the planetary gears 74c rotate about their own axes and are also revolutionized around the end gear section 60a, and the carrier 74b is also rotated in the same X direction. (3) Furthermore, in the third planetary gear assembly 76, as in the first planetary gear assembly, the outer planetary gear 76d attached to the second carrier 74b is rotated in the same section X as the end gear section 60a, - consequently, the planet gears 76c are rotated around their own axes and also revolution around the end gear section 60a, and the third carrier 76b is also rotated in the same X direction. The speed reduction ratio The speed reduction mechanism 54 can be expressed as follows: When Zo is the number of teeth of the internal planetary gear 72a, Zul is the number of teeth on the extreme gear section 60a (which constitutes the outer planetary gear of the first planetary gear), Zu2 is the number of teeth on the second external planetary gear 74d and Zu3 is the number of teeth on the third external planetary gear 76d, then the speed reduction ratio Rg = (l + Zo / Zul) x (l + Zo / Zu2) x (l + Zo / Zu3) In the present modality, for example, Zo = 36, and Zul = Zu2 = Zu3 = 12; consequently, the ratio of speed reduction Rg = 4x4x4 = 64. As a result of the rotation of the third (or upper) carrier 76b of the speed reduction mechanism 54 in the X direction as described above, the speed reduction output arrow 48 attached to the third carrier 76b is rotated in the X direction, and this rotational force is transmitted to the annular gears 44 of the external cutting units 12 in such a way as to rotate the annular gears 44 in the Y direction. As a result, the units external cutters 12 are rotated in the Y direction which is opposite from the gear section 60a to rotate in the X direction. Accordingly, the external cutters 36 are rotated together with the external cutting units 12 in the Y direction. In this case , the complete speed reduction ratio Ro of the external cutting units 12 with reference to the electric motor 18 can be expressed as: Where Z4 is the number of teeth on the speed reduction output gear 48, and Z5 is the number of teeth on the annular gears 44. In the above embodiment, for example, Z4 = 16 and Z 5 = 45; therefore, the ratio of speed reduction Ro = 64x45 / 16 = 180. As seen from the above, since the external cutters 36 are rotated, the hair such as pins, etc. they can be introduced directly into the slot (not shown) formed in the external cutters 36 even if the electric shaver 10 is not constantly moved around the skin as long as it is held with one hand. Accordingly, efficient shear is achieved, and fatigue of the arm muscles is relieved. In addition, the internal cutters 40 and the external cutters 36 are rotated in the same Y direction; however, the speed reduction ratio of the internal cutters 40 (relative to the motor 18) is approximately 2 (2.25), so that the internal cutters 40 rotate at a high speed; on the other hand, the speed reduction ratio of the external cutters 36 (relative to the motor 18) is 180, so that the external cutters 36 rotate at an extremely slow speed. Accordingly, as a result of the difference in the relative rotational speeds of the external cutters 36 and the internal cutters 40, the hairs introduced by means of the grooves in the external cutters 36, are cut by the constant force force. In addition, since the external cutters 36 are rotated very slowly, the skin directly contacting the external cutters 36 is not hurt by the friction generated between the skin and the external cutters 36. Furthermore, since the speed reduction ratio It is large, the external cutters 36 can rotate at a prescribed rotational speed against the contact resistance of the skin even if the electric motor with high torque is not used. In addition, the external cutters 36 and the internal cutters 40 are rotationally driven by means of an individual electric motor 18; consequently, the rotational speed ratio can remain constant (for example 2.25 to 180 in the above-described embodiment) even if the rotational speed of the electric motor 18 fluctuates due to variations in the voltage of the battery 20. Therefore, when the external cutters 36 are rotated at a rotational speed below 100 rpm (preferably from 40 to 60 rpm.), then the internal cutters' 40 are rotated at approximately 3,900 rpm. Further, since the individual electric motor 18 is used as the driving source of the external and internal cutters 36 and 40, the shaver can be made compact. Various aspects of a preferred embodiment of the present invention are described above. However, the present invention is not limited to the previous embodiment. In the above embodiment, three planetary gear mounts are employed. However, the number of planetary gear mounts can be modified in accordance with the desired speed reduction ratio of the speed reduction mechanism 54. For example, in cases where a smaller speed reduction ratio is sought, the planetary gear assembly number can be reduced to two (and not three), whereas when larger speed reduction ratios are preferred, the number of planetary gear assemblies can be increased up to four or more. Further, when a speed reduction mechanism formed by a plurality of planetary gear assemblies placed in multiple stages, they can also be used in cases when the number of external cutter units is one or two units. In addition, the diameters and numbers of the teeth of the gears and the number of the planetary gear assemblies used can be varied according to the specifications of the electric shaver requested, and the mode described above is only an example of the present invention. Furthermore, in the above embodiment, the internal cutters 40 and the external cutters 36 are rotated in the same direction, however, it is possible to design it so that those cutters are rotated in opposite directions. This is achieved by inserting reversing gears between the base gear section 60b and the internal cutter drive gears 66.

The present invention is not limited to the described embodiments, and it should not be said that several modifications are possible within the spirit of the present invention. As seen from the above detailed description, in accordance with the present invention, planetary gear assemblies are employed to reduce the rotational speed of the external cutters. Accordingly, such a speed reduction mechanism can be made more compact than the speed reduction mechanism using straight gears, and moreover a greater speed reduction ratio can be obtained. Further, in accordance with the present invention, a larger speed reduction ratio is obtained by placing a plurality of planetary gear assemblies in multiple stages, and internal planetary gears of this planetary gear assembly are formed in a single continuous cylindrical body; consequently, the constituent elements of the respective planetary gear assemblies such as planetary gears, external planetary gears and carriers, etc., can be accommodated within the cylindrical internal planetary gear element making it possible to reduce the size of the speed reduction mechanism itself. even more. Further, since the motor arrow gear coupled to the motor output shaft is used as the external planetary gear of the first planetary gear assembly between the planetary gear assemblies provided in multiple stages within the cylindrical internal planetary gear, the center rotation of the motor output shaft and the center of rotation of the speed reduction mechanism are in the same straight line. Accordingly, the overall external diameter of the speed reduction mechanism and the motor can be reduced, so that the electric shaver can be made more compact.

Claims (5)

1. An electric shaver equipped with an individual electric motor, external cutters that are rotationally driven by the electric motor, and internal cutters that are installed in combination with the external cutters and driven by the electric motor, the shaver that is provided with a mechanism of speed reduction constructed from a planetary gear assembly installed between a motor arrow gear, attached to an output shaft of the electric motor and gears installed on the external cutters.

2. An electric shaver according to claim 1, wherein the speed reduction mechanism comprises: a plurality of planetary gear assemblies, each consisting of an internal planetary gear, a plurality of planetary gears that are provided rotated on an carrier and coupling with the internal planetary gear, and the outer planetary gear is positioned at a center of such a plurality of planetary gears to couple with each of the planetary gears, and wherein such a plurality of planetary gears are provided in multiple stages, the inner planetary gear is formed in an individual cylindrical body to be commonly used with the planetary gears, and one of the planetary gear assemblies is interdependent with the outer planetary gear of another adjacent planetary gear assembly in a portion of the center of rotation of the cutter of gear assembly pla netary

3. An electric shaver according to claim 1 or 2, wherein the motor shaft gear is an external planetary gear of a first planetary gear assembly between the multi-stage planetary gear assemblies.

4. An electric shaver comprising an individual electric motor as a plurality of rotating circular external cutters, a plurality of internal cutters rotatably installed within the external cutters, and a speed reduction mechanism coupled to a plurality of external cutters, wherein an arrow The external motor of the individual electric motor is coaxially linked to the speed reduction mechanism having a speed reduction output gear interdependent with the gears provided on the peripheries of such plurality of external cutters so that the plurality of external cutters are rotated by the individual electric motor and the output arrow of the individual electric motor that is circumferentially linked to the gear chains, each coupled to each of the plurality of internal cutters so that the plurality of internal cutters are rotated by the electric motor individ ual.

5. An electric shaver according to claim 4, wherein the speed reduction mechanism comprises: an internal planetary gear of a cylindrical shape, and a plurality of carrier discs installed in the internal planetary gear to be placed parallel and one on the other, each of the plurality of carrier disk being provided with a plurality of gears is rotating planetary coupling with the internal planetary gear, and the plurality of carrier discs that are linked together by external planetary gears, each coupling with the gears planetary provided on each of the plurality of carrier discs, and wherein the output shaft of the motor is coupled by means of a motor shaft gear attached thereto to one of the plurality of carrier discs placed at one end of the gear internal planetary and the gear reduction output of the mechanism d The speed reduction is connected to another of the plurality of carrier discs placed at another end of the internal planetary gear.