Dry shaver

A dry shaver has an elongated shaving head with a lengthwise axis. The shaving head carries semi-cylindrical first and second outer cutters disposed on its opposite width ends, and a semi-cylindrical finishing cutter and a slit cutter interposed between the first and second outer cutters. The finishing cutter has a finishing foil which is deeply curved than a foil of the first and second outer cutters into an arcuate contour having a width less than that of the first and second outer cutters. The finishing foil disposed behind the first outer cutter comes into contact with a users skin to make closer shaving than the first and second cutters. A skin guard project between the first outer cutter and the finishing cutter to protect the skin from being pressed excessively to a side of the finishing foil when moving the shaving head across a user' skin with the first outer cutter leading in a moving direction, thereby reducing skin irritation.

TECHNICAL FIELD

The present invention is directed to a dry shaver, more particularly a dry shaver having multiple cutters.

BACKGROUND ART

Japanese Patent publication no. 8-318057 and U.S. Pat. No. 5,185,926 disclose a dry shaver having three elongated semi-circular cutters which are arranged in side-by-side relation with each other. One of the cutters is designed to project to a greater extent than the other cutter to define a finishing cutter which comes first into contact with a user skin for shaving hairs on a narrow area, for example, under a nose and chip top. Although it is found effective to make the intended shaving, the finishing cutter is likely to be pressed excessively at its one side when the shaving head is moving across the skin in a direction perpendicular to the length of the cutter, thereby causing skin irritation or even causing the skin to be cut. This is particularly true, when the finishing cutter is curved more deeply than the other to have an arcuate contour of reduced width. In other words, the deeply curved finishing cutter has an effective cutting zone only around its tip and is not successful to make smooth shaving free from pain at its side zones remote from the tip. Accordingly, when the deeply curved finishing cutter is interposed between the other cutters to project to a greater extent than the others, as seen in U.S. Pat. No. 5,185,926, there is always a risk of pressing the skin excessively at the side of the cutter and irritating the skin.

DISCLOSURE OF THE INVENTION

In view of the above problem, the present invention has been achieved to provide a dry shaver with multiple cutters which is capable of successfully shaving the hairs short on a narrow area without irritating the skin. The dry shaver in accordance with the present invention includes a shaving head which is elongated to have a lengthwise axis and is configured to carry a semi-cylindrical first outer cutter, a semi-cylindrical second outer cutter, and a semi-cylindrical finishing cutter which are all elongated along the lengthwise axis and are arranged in generally parallel relation with each other. Each of the semi-cylindrical first and second outer cutters includes a main foil with a number of perforations and an inner cutter driven by a motor to move in sliding contact with said foil. The main foil is arcuately curved about an axis parallel with the lengthwise axis into an arcuate contour. The semi-cylindrical finishing cutter includes a finishing foil with a number of perforations and an inner cutter driven by the motor to move in sliding contact with the finishing foil. The finishing foil is also arcuately curved about an axis parallel with the lengthwise axis into an arcuate contour having a width less than that of the first and semi-cylindrical second outer cutters. The semi-cylindrical first and second outer cutters are disposed on opposite width ends of the shaving head with the semi-cylindrical finishing cutter being interposed therebetween. The feature of the present invention resides in that the shaving head includes a skin guard which projects between the finishing cutter and one of the first and second outer cutters for contact with a user's skin.

Thus, the skin guard blocks the skin from entering into a recess between the finishing cutter and the adjacent cutter, thereby avoiding the skin from being pressed excessively against the side of the finishing cutter, i.e., an ineffective cutting zone when moving the shaving head across the skin with the first outer cutter leading in the moving direction, and therefore assuring a smooth close shaving without irritating the skin.

Preferably, the skin guard is floatingly supported to a frame of the shaving head and is spring-biased for pressed contact with the user's skin. Thus, the skin guard can be easily to follow the skin while the shaving head is manipulated to move across the skin, minimizing to drag the skin and therefore assuring a comfortable shaving.

The finishing foil may be also floatingly supported to the frame and is spring-biased upwardly for pressed contact with the user's skin. In this instance, the skin guard is coupled to the finishing foil to be movable together therewith to assure an optimum pressing contact of the finishing foil against the skin, while preventing the skin from engaging the side of the finishing foil.

The skin guard may be configured to have a roller or a comb for smooth engagement with the skin or hairs.

In a preferred embodiment, the shaving head additionally carries a slit cutter which is interposed between the finishing cutter and the second outer cutter to define another skin guard which blocks the skin from entering a recess between the finishing cutter and the second outer cutter, also for blocking the skin from contacting the side of the finishing semi-cylindrical cutter. The slit cutter is composed of an elongated outer blade with a number of slits opened at lateral edges of the outer blade, and an inner cutter driven by the motor to move in sliding contact with the outer blade. The outer blade is also supported to the frame, while the finishing foil and the slit cutter are floatingly supported to the frame and are spring biased for pressed contact with the user's skin. With this structure, the slit cutter acting as the skin guard can be depressed together with the finishing cutter and can be therefore kept in optimum contact with the skin, assuring to move the shaving head across the skin smoothly.

In order to place the individual cutters and also the skin guard in smooth contact with the skin, an optimum spatial arrangement are preferred with regard to these elements. That is, the finishing cutter has its top projected by a greater extent than that of said slit cutter, the slit cutter has its top end projected by a greater extent than that of the first outer cutter, and the skin guard between the finishing cutter and the first outer cutter projects to a height between the top end of the first outer cutter and the top end of the finishing cutter, and also at a level lower than the top end of the slit cutter.

Further, the outer blade may be coupled to the finishing foil by means of an adjustor spring so as to be urged from the finishing foil in a direction of being pressed against the user's skin. The adjustor spring generates a counter-spring force acting on the finishing cutter to reduce the spring-bias given per set thereto, thereby realizing the suitably adjusted spring-biases respectively to the finishing cutter and the slit cutter.

Moreover, the finishing foil may be configured to have a region where each of the perforations is surrounded partly by a thin section and partly by a thick section. The thin section gives an increased chance of introducing the hairs deep into the associated perforation for more effective close shaving.

These and still other advantageous features of the present invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the attached drawings.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now toFIGS. 1 to 5, there is shown a dry shaver in accordance with a preferred embodiment of the present invention. The dry shaver is composed of a hand grip60and a shaving head100mounted on top of the hand grip60. The shaving head100, which is elongated to have a lengthwise axis and a width axis, is connected to the grip60to be movable relative thereto about an axis perpendicular to the lengthwise axis. The shaving head100carries four differently configured cutters, namely, a semi-cylindrical first outer cutter10, a semi-cylindrical second outer cutter20, a semi-cylindrical finishing cutter30, and a slit cutter40. These cutters are all elongated along the lengthwise axis of the shaving head100and arranged in parallel relation with each other along the width axis.

The shaving head100is composed of a casing120and a frame130detachable to the casing120. The casing120is of a water-proof structure accommodating therein a linear motor150and is provided with a plurality of driving elements210,220,230, and240projecting on top of the casing120, as shown inFIG. 5. These driving elements are connected to the linear motor150to be driven thereby to reciprocate along the lengthwise axis of the shaving head100. The first and second outer cutters10and20are disposed on the opposite width ends of the shaving head100, with the finishing cutter30and the slit cutter40interposed therebetween. The grip60is provided with a trimmer80on its rear width end further away from the first cutter10than from the second cutter20.

The first and second outer cutters10and20are each composed of a main foil11and21, and an inner cutter16and26which are driven by the linear motor150to reciprocate in hair shearing engagement with the main foil. The main foil is formed with a plurality of perforations, and is arcuately curved about an axis parallel to the lengthwise axis of the shaving head100into an arcuate contour, i.e., semi-cylindrical shape having a width with respect to the with axis of the shaving head. The first and second outer cutters10and20are configured to have the main cutters of identical configurations, i.e., the same width and the same radius of curvature, as well as the inner cutters of identical configurations. As best shown inFIG. 4, the main foil11(21) is secured at its opposite lateral ends to a mount13(23), while the associated inner cutter16(26) is secured to a base17(27). The mount13(23) is floatingly supported to the frame130to be movable relative to the frame, and therefore to the casing120. The bases17and27are formed in their bottom respectively with catches18and28which detachably receive the driving elements210and220for reciprocating the inner cutters16and26. Each of the driving elements210and220carries a biasing spring212and222which gives a spring bias SB212(SB2222) urging the inner cutter and the associated main foil upwardly such that the first and second outer cutter10and20are capable of being depressed upon being pressed against a user's skin. The mounts13and23are secured respectively to a front cover111and a rear cover112which constitute a front wall and a rear wall of the shaving head100. The front cover111is provided at its lengthwise ends with studs19which are slidably engaged into corresponding vertical grooves131in the frame130. Likewise, the rear cover112is provided at its lengthwise ends with studs29which are slidably engaged into corresponding vertical grooves132in the frame130.

The finishing cutter30is introduced in the shaving head110in order to make making a closer shaving than the first and second cutters10and20, and is composed of a finishing foil31and an inner cutter36detachably connected to the reciprocating driving element230to be driven thereby to reciprocate in hair shearing engagement with the finishing foil31. The finishing foil31is formed with a plurality of perforations32and is arcuately curved about an axis parallel to the lengthwise axis of the shaving head100into an arcuate contour, i.e., semi-cylindrical shape having a width along the width axis of the shaving head. As best shown inFIGS. 3 and 6, the finishing foil31is deeply curved to have a radius of curvature smaller than that of the main foils11and21, and therefore the width W3smaller than those W1and W2of the main foils, thereby increasing a chance of capturing hairs deep into the perforations, particularly around a tip of the finishing foil31for cutting the hairs shorter than expected at the first and second cutters10and20, i.e., finishing the hairs to minimum length. As shown inFIG. 4, the finishing foil31is secured at its opposite lateral ends to a mount33, while the inner cutter36is fixed to a base37. The base37is formed in its bottom with a catch38which detachably receives the driving element230for reciprocating the inner cutter36. The mount33is floatingly supported to the frame130so as to be movable relative to the casing120of the shaving head100. The mount33is formed integrally with a skin guard50which projects between the first cuter cutter10and the finishing cutter30and is movable together with the finishing foil31relative to the casing120. The skin guard50extends in parallel and in closely adjacent relation to the side of the finishing foil31. The mount33is formed at its opposite lengthwise ends with side covers113which constitute portion of side walls of the shaving head100. The driving element230carries a spring232which gives a spring bias SB232urging the inner cutter against the finishing foil31and therefore the finishing cutter31upwardly such that the finishing cutter31is capable of being depressed upon being pressed against with the user's skin. The mount33is also formed at its opposite lengthwise ends with studs39which are held slidable in corresponding grooves133in the frame130so that the finishing cutter30is movable relative to the frame130as being biased upwardly by the spring232.

The slit cutter40is composed of an elongated outer blade41with a number of slits opened at lateral edges of the outer blade41, and an inner cutter46driven to reciprocate in hair shearing engagement with the outer blade41. The outer blade41is shaped to have a generally flat top surface for sliding contact with the user's skin to capture flattened hairs into the slits for cutting the hairs. The outer blade41is fixed to a mount43which is floatingly supported to the frame130. The inner cutter46is secured to a base47which is slidably held on the mount43to reciprocate the inner cutter46relative to the outer blade41. Springs44are interposed between the mount43and the base47to keep the inner cutter46pressed against the outer blade41. The frame43is formed at its opposite lengthwise ends with studs49which are slidably engaged into corresponding grooves134in the frame130for floatingly support the slit cutter40to the frame130. The base47is formed in its bottom with a catch48which detachably receives the driving element240for reciprocating the inner cutter46. As shown inFIG. 5, the driving element240is integrally formed with the driving element220but gives no bias to the slit cutter40. Instead, springs45are interposed between the frame43and extensions34extending from the mount33of the finishing cutter30to give a sprig bias SB45urging the slit cutter40upwardly.

FIG. 6shows a height relationship among the four cutters in a free condition of not being depressed or not being held in pressed contact with the user's skin. The second cutter20and the finishing cutter30are disposed to have their tips at the same level, while the first cutter10has its tip lowered by a large difference D1from that of the finishing cutter30, and the slit cutter40has its tip lowered by a small difference D4from that of the finishing cutter30. The skin guard50which is movable together with the finishing cutter30has its tip disposed at a level higher that that of the first cutter10but is lower than that of the finishing cutter30by a difference of D5. With this multi-cutter arrangement, each cutter can be held in an optimum contact with the user's skin for effective shaving. For example, when shaving hairs under the chin, as shown inFIG. 8, with the first cutter10ahead in the moving direction, the cutters are simultaneously held in contact with the skin to make the individual shaving effectively. On the other hand, when shaving a narrow area such as a chin top, as shown inFIG. 9, the finishing cutter30can be pressed against the skin in combination with the skin guard50and the slit cutter40so as to cut the hairs to minimum. In this connection, it is noted that as a result of being deeply curved, the finishing foil31is given an effective cutting zone only around its tip and leave ineffective zones respectively on its opposite sides where the skin is likely to cause skin irritation when being pressed hard against the skin. That is, as shown inFIGS. 7(A)and (B), as the foil F is curved deeper, the foil is caused to be pressed against at a greater angle (α1, α2) of contact on its leading side with respect to a direction of moving the shaving head, and is therefore pressed at a greater force against the skin S, which eventually increases a chance of capturing the skin deep through the perforations in the foil, and accordingly irritating the skin. In this sense, the lower portion on the side of the deeply curved finishing cutter30is not suitable for pleasant shaving in a situation when the shaving head is moving around the skin with the finishing cutter being pressed at its leading side against the skin, while the upper portion of the side of the finishing cutter is effectively utilized for cutting the hairs minimum.

In order to avoid the skin from contacting the lower portion of the side of the finishing cutter, i.e., ineffective zone, the skin guard50is positioned to cover ineffective zone in closely adjacent relation thereto with its top slightly lowered from the tip of the finishing cutter30, for the purpose of exposing the effective zone, i.e., the upper portion of the finishing cutter30around its tip for close shaving. In this connection, the skin guard50is offset towards the finishing cutter30so as not to interfere with the shaving operation of the first outer cutter10. The slit cutter40also act as another skin guard in a sense of avoiding the skin from contacting with the lower side portion of the finishing cutter30and minimizing the skin irritation, when the shaving head100is moving with the second outer cutter20leading in the direction of movement.

Turning back toFIG. 6, the finishing foil31is urged upwardly also by adjustor springs35interposed between the frame33of the finishing foil31and projections14extending from the frame13of the first outer cutter10such that the finishing foil31receives an upward spring-bias which is a combination of the upward spring bias SB232from the spring232of the driving element230, and an upward additional spring bias SB35by the adjustor spring35, and the downward spring bias CF45, which is a counter-force of the springs45urging the slit cutter40upwardly. The adjustor springs35develop a counter-force CF35which urges the main foil11of the first outer cutter10downwards such that the first outer cutter10receives an upward spring bias, a combination of the upward spring bias SB212from the spring212of the driving element210and the downward bias CF35of the adjustor springs35. Thus, as schematically illustrated by corresponding arrows inFIG. 6, the individual cutters are given optimum spring bias by use of the adjustor springs35and45. Particularly, the first outer cutter10and the second outer cutter20can be given different spring biases, while using the driving elements210and220of the same configuration, i.e., the springs212and222of the same spring forces. For example, when the driving elements210,230, and220are selected to have spring biases SB212, SB232, and SB222respectively of 1.2 N, 1.0 N, and 1.2 N, in combination with the adjustor springs35having the spring force of 0.5 N, and the springs45having the spring force of 0.8N, the first outer cutter10, the finishing cutter30, the slit cutter40, and the second outer cutter20are given the spring biases of 0.7 N (=1.2 N−0.5 N), 0.7 N (=1.0 N+0.5 N−0.8 N), 0.8 N, and 1.2 N, respectively.

Referring toFIGS. 10 and 11, the finishing foil31are now explained in details with respect to its structural feature. The perforations32are arranged in an array composed of rows aligned with a length of the foil and columns aligned along a direction slightly inclined with respect to a width direction of the foil. As shown inFIG. 11, the foil31is formed in its top surface with a plurality of recesses140arranged along each column in an alternating relation with the perforations32to define plural series of thin sections140of reduced thickness, leaving the other portions as thick sections142which continuously extends over the full width of the foil31between the adjacent columns of the perforations32. With this result, each of the perforations32has its circumference partly defined by the thin sections140and partly by the thick sections142. Since the thin sections140alternate with the perforations32along the column, the hairs are guided along a series of the thin sections140as the shaving head100is moved across the skin with the cutter being oriented to have its width in generally perpendicular to the moving direction, during which the flattened hairs can be easily guided into the perforations through the thin sections and are raised at the edge of the perforation32adjacent the thin section140for successfully cutting the flattened hairs. On the other hand, the thick sections142provide flat faces which extend continuously along the columns, or the width direction of the foil31to give a smooth skin contact for facilitating the shaving, while retaining the effect of raising and cutting the flattened hairs by provision of the thin sections140. For instance, the thick section is selected to have a thickness of 50 μm to 80 μm, while the thin section140has a thickness of 45 μm or less. In this connection, the main foils11and21are each formed from a foil of uniform thickness which is greater than that of the thin section140and is equal to or greater than that of the thick section142.

As shown inFIG. 11, each of the perforations32are shaped into a hexagon having an opposed pair of long sides and two opposed pairs of short sides. The thin sections140merge into the long sides, while the thick sections142merges into the short sides. That is, each perforation32is surrounded at its long sides by the thin sections140and at its short sides surrounded by the thick sections142. The thin section140has its top surface connected to the top surface of the thick sections142by way of inclined shoulders141. The hexagon is dimensioned, for example, to have a length of 0.5 mm in the row direction, and a width of 0.3 mm in the column direction.

As shown inFIGS. 12 and 13, each perforation32is surrounded by a raised rim144which projects on bottom of the foil31, and is shaped to have inclined edges145and146, respectively leading from the long sides and short sides. The inclined edge145extends continuously from the thin section140is given at its lower end a cutting angle of β1 smaller than the cutting angle of β2 at the lower end of the inclined edge146. The smaller cutting angle of β1 is found advantageous to enhance the effect of raising the flattened hairs guided by the thin sections140. Further, the finishing foil31is configured to include the thick sections142which occupy a larger area than the thin section140, in order to give sufficient mechanical strength and assure the smooth skin contact.

Although the above embodiment illustrates that the finishing foil31includes the thin sections and the thick sections, it may be equally possible that the finishing foil31is devoid of the thick sections to have a uniform thickness which is less than that of the main foil. Further, the main foils11and21of the first outer cutter10and the second outer cutter20may be selected to have the like configuration including the thin sections and the thick section, provided that the finishing foil31has its width less than that of the main foil. The present invention therefore encompass a structure in which the finishing foil31is shaped to have its width smaller than that of the main foil, and/or the finishing foil31includes the thin section around each perforation where the thin section has a thickness less than that of the main foil.

Further, as shown inFIGS. 14 and 15, the above skin guard50may be modified to include a roller52for rolling contact with the user's skin. The roller52is configured to have axles54which project on opposite ends of the roller52and are rotatably supported to brackets56fixed to the mount carrying the finishing foil31.

Alternatively, the skin guard50may be shaped to have a comb51with a number of teeth, as shown inFIG. 16, for smoothening the hairs prior to introducing the hairs to the finishing cutter30.

In the illustrated embodiment, each of the cutters10,20,30, and40as well as the skin guard50are slightly curved arcuately with respect to the lengthwise axis for smooth contact with the skin. However, the present invention should not be interpreted to be limited thereto and may equally encompass the arrangement in which at least one of the cutters and the skin guard is configured to have straight top surface with respect to the lengthwise direction.