Electric shaver

Abstract: An electric shaver (10) having a shaving head (20) which can pivot and be depressed into the housing (12) of the shaver (10). The shaving head (20) is mounted on pivot shafts (16) that can be moved toward the inside of the shaver housing (12), thus allowing the shaving head (20) to be pressed into the housing (12) but bounce back to the original position by vertical springs (18); and the shaving head (20) also pivots about the pivot shafts but is forced back to its original and upright position by lateral springs (34).

Description: The present invention relates to an electric shaver. One example of a conventional electric shaver of a vibration type has a shaving head that pivots between a pair of supporting elements installed in the shaver's main-body housing. The shaving head has inner and outer blades, and the inner blade vibrates to slide along the undersurface of the outer blade to cut the hair. Such an electric shaver is disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) No. 62-227395. In this electric shaver, the axial line of the pivotal shaving head lies on the axis of the outer blade; and the outer blade is not movable in a vertical direction so that the apex of the outer blade is kept in contact with the skin when the shaver is used. In this shaver, since the outer blade is positioned on the axial line of the pivotal shaft of the shaving head, and the shaving surface of the outer blade is not designed to move up and down relative to the axial line of the pivotal shaft, the shaving head is not movable into and away from the housing of the shaver. As a result, the shaving head merely makes a pivotal motion and the outer blade passes over the skin by such a pivotal or swinging motion of the shaving head; thus, shaving that conforms to one's facial configuration is not well executed. More specifically, when it is intended to move the outer blade along an uneven facial configuration, it is necessary to move the main body of the shaver to and away from the shaving target point on the face. In addition, since the shaving head can make pivot motions, if the shaver is moved with the outer blade being pressed strongly against the skin, the shaving head pivots in the opposite direction from the direction the shaver is moved on the face. Consequently, the deep cutting of whiskers that is done by stretching the skin while moving the shaver finely back and forth at the target point on the face is not available. DE-A-4244164 from which the features of the preamble of claim 1 are known discloses a razor having shaving head which supports cutting blades, the shaving head being pivotally mounted to the razor housing. The shaving head is also mounted to allow vertical movement of the shaving head with respect to the housing and a connecting assembly is provided to connect the cutting blades to a driving motor while allowing the shaving head to both pivot and move vertically. Accordingly, a primary aim of embodiments of the present invention is to provide an electric shaver which has a shaving head that is pivotal with respect to the skin and at the same time depressable into the shaver housing, so that whiskers can be cut with the skin stretched. It is another aim of embodiments of the present invention to provide an electric shaver which can absorb the shock that might occur when the outer blade of the shaving head is pressed strongly against the skin. According to one aspect of the present invention, there is provided an electric shaver comprising a shaving head having an outer blade and an inner blade which slides along an inside of said outer blade, a housing in which said shaving head is supported so that said shaving head is free to pivot about pivot shafts between a pair of supporting elements which are installed facing each other at one end of said housing, said housing being provided with therein a motor, and a connecting assembly which connects an output shaft of said motor to said inner blade so as to drive said inner blade while allowing pivoting and inward depression motions of said shaving head, said shaver being characterized in that said pivot shafts are supported in a movable manner on said supporting elements via pressing means so that said shaving head that overcomes a pressing force of said pressing means can be depressed toward an inside of said housing. In the above structure, it is preferable to have guide grooves on the facing surfaces of the supporting elements so that a floating bearing which supports the pivot shafts are set inside the guide grooves in a movable fashion and that the pressing elements are installed in the grooves. Furthermore, the floating bearing may be formed in a reversed C-shape in cross section that opens toward the housing so that the pressing elements are set inside the floating bearing. In addition, the connecting assembly may comprise a vibration plate and an eccentric cam. The inner blades may be mounted to the vibration plate, and the vibration plate may be provided inside the shaving head so that the vibration plate can make a reciprocating motion in the axial direction of the pivot shafts; and in addition, the vibration plate may have a long slot opened in the direction perpendicular to the reciprocating motion of the inner blades. The eccentric cam may be fitted on the output shaft of the motor and may have an eccentric shaft at a position offset from the output shaft; and the eccentric shaft may be inserted loosely into the long slot of the vibration plate. With the structure described above, the shaver may be used by bringing the outer blade to contact the skin, and the electric shaver as a whole moved over the skin, so that the outer blade is caused to rub across the skin to cut whiskers. In this case, the shaving head may be inclined in the direction opposite from the cutting direction and depressed slightly into the housing so that the head conforms to one's facial configuration. Since the distance between the outer blade and the axial line of the pivot shafts on which the shaving head is supported may differ at various positions, the strength with which the shaving head is pressed against the skin may vary depending upon the pivotal motion of the shaving head. Thus, deep shaving may be performed. In addition, when the outer blade is strongly pressed against the skin, the shaving head may be depressed toward the inside of the housing, thus the shock of the contact may be absorbed. Meanwhile, the shaving head may be urged to stay in the neutral or upright position by installing lateral spring elements between the shaving head and the housing; and with this structure, the outer blade may bite into the skin as a result of the reaction force of such a shaving head position. For a better understanding of the present invention and as to how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings in which: Figure 1 is a partially sectional front view showing the internal mechanism of the electric shaver embodying the present invention; Figure 2 is a side view thereof; Figure 3 is a side view of the shaver embodying the present invention with a part thereof shown as a cross section; Figure 4 is a front view of the vibration plate used in the shaver embodying the present invention; Figure 5 is a top view thereof; Figure 6 is a bottom view of the head case of the shaver embodying the present invention; and Figure 7 is a side view of the shaver, illustrating the floating structure of the shaving head shown particularly in cross section. In Figures 1 and 2, the electric shaver embodying the present invention is generally referred to with the reference numeral 10 and includes a housing 12 and a shaving head 20. The housing 12 has a pair of supporting elements 12A in a manner that the supporting elements 12A face each other and an opening 12a at one end or at an open end thereof (which is at the top end in the Figures). The upper ends of the supporting elements 12A are bent inward to form the opening 12a. The shaving head 20 is fitted inside the opening 12a. A pair of floating bearings 14, each in a gate-form shape when seen from the side, are installed in recessed areas 13 which are formed as guide grooves in the respective inside surfaces of the supporting elements 12A. The shaving head 20 is mounted on these floating bearings 14 via pivot shafts 16 provided in the bearings 14 in a manner that the shaving head 20 can pivot about the pivot shafts 16. The pivot shafts 16 are positionally coaxial and project toward each other and are located in positions whose distance from the bottom of the shaving head 20 is equal to about 1/4 the height (in the vertical direction in Figure 1) of the shaving head 20. The floating bearings 14 have projections 14a projecting downward from the inside lower surfaces of the floating bearings 14, and the upper ends (in Figure 1) of springs or pressing elements 18 are fitted over these projections 14a. The lower ends of these springs 18 are in contact with the bottom surfaces 13a of the recessed areas 13, so that the floating bearings 14 are constantly urged upwardly by the springs 18 and contact the ceiling surfaces 13b of the recessed areas 13. In other words, the pivot shafts 16 are kept pushed toward the opening 12a of the housing 10 by vertical pushing elements 18. This state is considered to be the initial position. Furthermore, as shown in Figure 3, the floating bearings 14 (only one bearing is shown in Figure 3) are provided with engaging parts 14c which extend outwardly from the lower areas of the floating bearings 14 in the direction of thickness (right and left directions in Figure 3) of the housing 12. These engaging parts 14c respectively engage with step parts 13c formed in the lower portions of each recessed area 13; and when force (which is, for example, in a vertical direction in Figure 3) is applied to the shaving head 20, the shaving head 20 is depressed toward the inside of the housing 12 together with the floating bearings 14. As seen from Figure 3, the pivot shaft 16 and the spring 18 are provided substantially at the center in the direction of the thickness of the shaver 10. An outer blade 22 which, as best seen in Figure 1, consists of two continuous peak-shaped projections is installed on the apex of the shaving head 20. A pair of inner blade units 24 are positioned so that they are in the respective projections of the outer blade 22. Thus, the embodiment shows a so-called dual track shaver as an example. Each of the inner blade units 24 has a conventional well known structure. In other words, shafts 24a which connects a pair of side plates 24b positioned parallel to the direction of thickness (right and left directions in Figure 2) of the housing 12 is installed in the lower center of each of the inner blade units 24, and a multiple number of plate blades 24c are installed at equal intervals on the side plates 24b (see Figure 1) in such a manner that as shown in Figure 2 the blades 24c straddle the space between the two side plates 24b. The shaft 24a of each one of the inner blade units 24 is connected to a vibration plate 26 which is installed on the bottom 20a of the head case 20A of the shaving head 20 so that the vibration plate 26 is positioned in a space formed between the bottom 20a and partition bodies 28. As shown in Figures 4 and 5, the vibration plate 26 has mounting areas 26a at both ends in the direction of the length of the vibration plate 26. These mounting areas 26a are connected to a central vibration area 26b via thin deformable connecting strips 26c which have a flat "S" shape so that the central vibration area 26b of the vibration plate 26 reciprocates in the left-right direction in Figures 4 and 5, in other words, in the axial direction of the pivot shafts 16 when actuated as described below. The mounting areas 26a are secured in the space formed between the bottom 20a and the partition body 28 so as to be located at both ends of the space in the direction of the supporting elements 12A. The vibration plate 26 has two supporting tubes 30 provided upright on the upper surface of the vibration area 26b of the vibration plate 26. The supporting tubes 30 are located at the middle in the length wise direction of the vibration plate 26. As seen from Figure 1, these supporting tubes 30 upwardly penetrate through the central opening 28a that is formed in the partition body 28. Furthermore, as shown in Figure 2, covers 29 made of rubber are installed so that the gaps between the supporting tubes 30 and the rim of the opening 28a of the partition body 28 are closed off. When the vibration plate 26 is reciprocated, the gaps between the supporting tubes 30 and the rim of the opening 28a are kept closed-off by the covers 29 that are deformed by the reciprocating motion of the vibration plate 26. Each of the supporting tubes 30 is, as seen from Figure 5, formed in the shape of a flattened oval having the longer diameter oriented in the direction of the reciprocating motion of the vibration plate 26 (right and left in Figures 4 and 5). Furthermore, as seen in Figure 4, a slit 30a is formed in the direction of the shorter diameter of the flattened oval-shaped tube 30, and locking projections 30b which project toward each other are formed on the inner surfaces of and at the upper end of the slit 30a. As seen in Figure 1, the lower end of the shaft 24a of the inner blade unit 24 is inserted into the slits 30a of the supporting tube 30 by letting the shaft 24a ride over the locking projections 30b. In addition, a spring 32 is installed between each shaft 24 and each inside bottom of the corresponding supporting tube 30 so that the top edges of the blades of the inner blade unit 24 are kept in contact with the under surface of the outer blade 22 by the spring force of the spring 32. When the outer blade 22 is deformed during the use of the shaver and the force is applied onto the inner blade units 24, the inner blade units 24 can be depressed inwardly so that the force is absorbed. The depression movement distance of the inner blade units 24 is indicated by L in Figure 4 which is substantially equal to the depth of the slit 30a. The shaving head 20 is provided with projections 21' and 21" as shown in Figure 6. The projections are on the bottom surface of the head case 20A that is a part of the shaving head 20. Springs 34 are, as shown in Figure 1, connected between each of these projections 21' and 21" and the inner wall surface of the housing 12. The arrows A in Figure 6 indicate the directions of the tension of the thus installed springs 34. More specifically, these springs 34 are positioned substantially laterally as seen in Figure 1. In addition, the springs 34 are provided so that one spring 34 is between the projection 21' and the inner surface of the front wall of the housing 12, and the other spring 34 is between the projection 21" and the inner surface of the back wall of the housing 12. With these lateral springs 34, the shaving head 20 can be kept in a neutral position (which is the upright position of the shaving head 20 as shown in Figure 2 and not inclined to either the right or left in Figure 2). When the shaving head 20 is depressed toward the inside of the housing 12, the springs 34 (which are coil springs) can expand and contract so as to follow such a head depressing motion. A driving motor 36 that has an output shaft 36a is installed inside the housing 12 so as to be slightly above the middle point (in a vertical direction) of the housing 12 in Figure 1, and the power of the motor 36 is transmitted to the inner blade units 24 via a connecting assembly. The connecting assembly has a structure as described below. The connecting assembly comprises, as best seen in Figure 2, a first eccentric cam 38 fitted on the output shaft 36a of the motor 36, a first eccentric shaft 38a formed on the first cam 38, a second eccentric cam 40 coupled to the first shaft 38a, and a second eccentric shaft 40a formed on the second cam 40. More specifically, the first eccentric shaft 38a projects from the upper surface of the first eccentric cam 38 such that the axis of the shaft 38a is in an eccentric position which is offset from the axis of the output shaft 36a of the motor 36. The second eccentric cam 40 is fitted on the first eccentric shaft 38a, and the second eccentric shaft 40a projects from the upper surface of this second eccentric cam 40 such that the axis of the second eccentric shaft 40a is in an eccentric position which is offset from the axis of the output shaft 36a of the motor 36. Furthermore, the eccentric shaft 40a is inserted loosely into an engagement hole 41a of a movable element 41, which has a shallow U-shape configuration as best seen in Figure 1. The movable element 41 is fastened at its upper portion to the projection 27 (see Figure 4) formed on the undersurface of the vibration plate 26, and the engagement hole 41a is formed in its lower portion of the movable element 41. As is clear from Figures 1 and 2, the engagement hole 41a is a long slot oriented in the direction of the thickness of the housing 12 (right and left directions in Figure 2), in other words, the hole 41a is long in the direction perpendicular to the axes of the pivot shafts 16. The eccentric shaft 40a of the connecting assembly is brought into this slot or hole 41a loosely in the direction of the thickness as referred to above, so that the vibration plate 26 can make only a horizontally reciprocating motion as shown by arrow R (or in the left-right direction) in Figure 1 without hindering the shaving head 20 from making a pivotal motion as indicated by arrow P in Figure 2. With the above described connecting assembly, the rotation of the output shaft 36a of the motor 36 is transmitted to the movable element 41 via the eccentric cams 38 and 40 so as to vibrate the vibration plate 26 laterally, thus making the reciprocating motion of the inner blade units 24. As described above, the shaving head 20 can not only be pivoted about the pivot shafts 16 by a force that overcomes the spring force of the lateral springs 34 but can also be depressed into the housing 12 by a force that overcomes the spring force of the vertical springs 18. However, the length of the eccentric shaft 40a is set so that the eccentric shaft 40a does not disengage from the engagement hole 41a of the movable body 41 even when the head 20 is depressed and pivoted. In addition, an escape hole 26d is formed in the undersurface of the vibration plate 26 so that the eccentric shaft 40a does not contact the vibration plate 26 even when the shaving head 20 is pivoted and depressed. In other words, the transmission of the driving force of the motor 36 to the inner blade units 24 is not hindered even when the shaving head 20 is pivoted about the shafts 16 and depressed into the housing 12. In the above, the movable element 41 which has the engagement hole 41a is a separate element from the vibration plate 26. However, it would be possible to form the engagement hole 41a directly in the vibration plate 26. The reference numerals 56 shown in Figure 2 are elastic elements. These elastic elements 56 are installed on the edges of the opening 12a of the housing 12 that are located in the pivoting direction P of the shaving head 20 so that the elastic elements 56 insure that no gap is formed between the shaving head 20 and the shaver housing 12 when the shaving head 20 is pivoted and depressed. Next, the structure of trimmer unit 46 and the driving force transmission mechanism therefor will be described. The trimmer unit 46 is provided on the back of the shaver housing 12 and actuated by the motor 36 via an oscillating element 42. More specifically, the first eccentric cam 38 of the connecting assembly connecting the motor 36 to the inner blade units 24 is, as shown in Figures 1 and 2, set in a through-hole 42a that is formed in the center of the oscillating element 42, and a crank arm 44 is installed so as to connect the pin 42b formed on the upper surface of the oscillating element 42 and the eccentric shaft 38a of the first eccentric cam 38. As a result, when the first eccentric cam 38 is rotated by the motor 36, the oscillating element 42 is oscillated in the left-right direction R in Figure 1 by the crank arm 44. The oscillating element 42 has U shaped connecting arms 43 on both sides, as best seen in Figure 1, and is fastened to the housing 12 via these connecting arms 43. The outside walls 43a of the connecting arms 43 are formed thin so as to be deformed; thus, the oscillating element 42 can oscillate in the direction of the connecting arms 43. As shown in Figure 2, the oscillating element 42 has a guide groove 45 on the back. The guide groove 45 is open at its top and bottom. When the trimmer unit 46 is moved up in Figure 2, the tip or top end of a drive element 48 engages with the guide groove 45, and the oscillation motion of the oscillating element 42 is transferred to the trimmer unit 46 via such engagement of the drive element 48 and the guide groove 45 of the oscillating element 42. The trimmer unit 46 includes a cover 50 which moves along the back surface of the housing 12, an immovable blade 52a and a movable blade 52b provided in an opening 50a which opens laterally (in Figure 1) in the upper portion of the cover 50, and the drive element 48. The upper end of the drive element 48 is engaged with the movable blade 52b. The drive element 48 is at its intermediate point provided on a shaft 49 inside the cover 50 so that the drive element 48 can oscillate in the direction R on the shaft 49. When the drive element 48 is pushed by hand and engaged with the guide groove 45 of the oscillating element 42, the drive element 48 is oscillated so that the movable blade 52b engaged to the drive element 48 slides along the immovable blade 52a, thus trimming hairs by the two blades 52a and 52b. The electric shaver of the present embodiment is constructed as described above, and shaving is accomplished by switching the power of the electric shaver 10 on and moving the shaver 10 around on the skin while pressing the outer blade 22 of the shaving head 20 against the skin. When the shaver 10 is moved on the skin, the shaving head 20 can pivot about the pivot shafts 16 so that the orientation of the outer blade 22 switches so as to conform to the configuration of the face. Thus, shaving is accomplished with the shaving head 20 kept pressed against the skin; and since the shaving head 20 is supported by the floating bearings 14, when a force is applied to the shaving head 20 or the shaving head 20 is pressed against the skin strongly, the shaving head 20 is depressed into the shaver housing 12 by overcoming the spring force of the springs 18 so that the force can be absorbed. As a result, the load applied to the outer blade 22 can be absorbed too. The shaving action will now be described in greater detail. When the electric shaver 10 as a whole is moved over the skin, the outer blade 22 rubs across the skin and cuts whiskers. In this case, the shaving head 20 can incline in the direction opposite from the shaving direction and is depressed inwardly; thus, the shaving head 20 can conform to any facial configuration and shaving is accomplished with the shaving head 20 fitted properly against the skin. In addition, the distance between the outer blade and the axial line of the pivot shafts 16 on which the shaving head 20 is supported can differ at various positions along the outer blade, and the strength with which the shaving head is pressed against the skin can vary depending upon the pivoting motion of the shaving head; thus, it is possible to perform deep shaving. In addition, because of the laterally oriented springs 34, the shaving head 20 tends to keep its neutral or upright position, and the reaction force of such tendency causes a pivot motion of the shaving head 20 in the direction opposite from the movement of the shaver. Thus, the outer blade 22 can bite in more strongly, making deep shaving possible. In the embodiment described above, the shaving head 20 is supported on the floating bearings 14 via the pivot shafts 16 so that the shaving head 20 may pivot about these shafts 16, and the floating bearings 14 are supported by vertically oriented springs 18 so as to be depressed toward the inside of the housing. However, it is also possible to construct the shaver as shown in Figure 7. In this case, guide grooves 12b (only one shown) which guide the pivot shafts 16 (only one shown) in an up and down direction in Figure 7 are formed in the inside surfaces of the supporting elements 12A, bearing elements 15 (only one shown) which support the pivot shafts 16 are installed inside these guide grooves 12b, and springs (only one shown) 18 are installed between these bearing elements 15 and the bottom surfaces of the guide grooves 12b. In this structure, the shaving head 20 pivots about the pivot shafts 16 and is free to move up and down. As seen from above, according to embodiments of the present invention, the shaving head is supported between a pair of supporting shafts so that the shaving head can pivot about these supporting shafts. In addition, the pivot shafts can be depressed toward the inside of the housing. Accordingly, when a large force is applied to the shaving head, the shaving head is depressed into the housing, and the force is absorbed. Thus, the load applied to the outer blade can be absorbed. In addition, when the shaver embodying the present invention is moved around on the skin so that the outer blade rubs across the skin and cuts whiskers, the shaving head is inclined in the direction opposite from the shaving direction and is depressed inwardly so that it conforms to the facial configuration. Accordingly, shaving can be accomplished with the shaving head fitted always on the skin. Moreover, since the distance between the outer blade and the axial line of the pivot shafts on which the shaving head is mounted may differ at various positions along the outer blade, the strength with which the shaving head is pressed against the skin can vary depending upon the pivoting movement of the shaving head, so that deep shaving is possible. Furthermore, since shaving can be accomplished with the outer blade of the shaving head fitted against the skin, whiskers can be shaved by rubbing the skin with the head inclined; and since the pivoting shaving head is kept so as to be in a neutral or upright position by the spring force, the reaction force causes the outer blade to bite more strongly into the skin.

Claims: An electric shaver (10) comprising: a shaving head (20) having an outer blade (22) and an inner blade (24) which slides along an inside of said outer blade, a housing (12) in which said shaving head (20) is supported so that said shaving head is free to pivot about pivot shafts (16) between a pair of supporting elements (12A) which are installed facing each other at one end of said housing (12), said housing being provided with therein a motor (36), and a connecting assembly which connects an output shaft (36a) of said motor (36) to said inner blade (24) so as to drive said inner blade while allowing pivoting and inward depression motions of said shaving head (20), said shaver being characterized in that: said pivot shafts (16) are supported in a movable manner on said supporting elements (12A) via pressing means (18) so that said shaving head (20) that overcomes a pressing force of said pressing means (18) can be depressed toward an inside of said housing (12). An electric shaving according to claim 1 wherein guide grooves (13) are formed in facing surfaces of said supporting elements (12A), floating bearings (14) which support said pivot shafts (16) are provided inside said guide grooves (13) so that said floating bearings (14) are capable of movement, and said pressing means (18) are installed inside said grooves. An electric shaver according to claim 2 wherein said floating bearings (14) are formed so that they have C-shaped cross sections that open toward said housing (12), and said pressing means (18) are installed so that they are positioned inside said floating bearings. An electric shaver according to claim 1, 2 or 3 wherein said connecting assembly comprises: a vibration plate (26) to which said inner blade (24) is connected, said vibration plate being supported inside said shaving head (20) so that said vibration plate (26) is able to make a reciprocating motion in an axial direction of said pivot shafts (16) of said shaving head (20) and having a long slot (30a) formed in a direction perpendicular to said reciprocating motion, and an eccentric cam (38) fitted on said output shaft (35a) of said motor (36) and having an eccentric shaft (38a) in a position offset from said output shaft (30a) so that said eccentric shaft (38a) is inserted loosely into said slit (30a) of said vibration plate (26). An electric shaver according to claim 1, 2 or 3 wherein a multiple number of tension springs (34) are provided with different orientations so as to position said shaving head (20) in a neutral position, each of said tension springs (34) having one end fastened to said housing (12) and another thereof being fastened to said shaving head (20). An electric shaver according to claim 4 wherein a multiple number of tension springs (34) are provided with different orientations so as to position said shaving head (20) in a neutral position, each of said tension springs (34) having one end fastened to said housing (12) and another end thereof being fastened to said shaving head (20).

Inventors: OZAWA TETSUYA, OZAWA, TETSUYA
Applicants: IZUMI PROD CO, IZUMI PRODUCTS COMPANY
Application year: 1995
Main classification: B26B19
IPC codes: B26B19