BLADE ASSEMBLY

Abstract: A blade assembly (10) comprises first and second blades (24 and 24′) which are pivotally mounted to the rest of the assembly (10). This enables the span of each blade to be altered in response to the amount of shaving force generated by the user.

Description: This invention relates to a blade assembly. More specifically the invention relates to a dynamic shaving system and particularly a shaving system in which the span of the blade changes with forces exerted during shaving. It has long been recognized that shaving a flexible complex surface like the face with an immovable system such as the conventional razor produces nicks, cuts and lack of uniformity of shaving due to the varying face profile of the shaver. Closeness of the shave is dependent upon, among other factors, the angle of contact between face and blade as well as the flow of skin immediately preceding contact with the blade. One of the factors controlling this flow of skin is the distance between the blade edge and the surface of the blade assembly which contacts the face immediately prior to the blade edge. This distance measured by the tangential line between the face engaging points of the blade and the leading surface is known as span. In a two blade system, each blade has a separate span. The leading or bottom blade has a span determined by the tangent line drawn between its edge and the leading edge of the guard bar which is part of the blade support structure and designed to, at least in part, direct skin flow to the blade. The second blade has a span measured by a tangent line drawn between the first and second blade. In the case of the two blade system the first or bottom blade determines the skin flow to the second blade. Several attempts have been made in the past to control the shaving properties of the blade assembly by providing the blade assembly with flexible or movable components in various combinations. US-A-4,516,320 discloses a blade assembly with flexible blades and spacer which move downward in response to shaving forces and the guard bar which flexes inward and upward. US-A-4,443,939 describes a blade assembly in which a cap and guard bar as well as blades and spacer are flexible and tend to conform to the facial curves of shaving pressures applied. US-A-4,069,580 and US-A-4,409,735 disclose a flexible razor produced by utilizing a flexible guard bar and flexible cap as well as flexible blades and spacers. A series of ten patents issued to Chester F. Jacobson of which US-A-4,587,729 is the latest, describes a blade assembly with blades which are individually biased and move linearly reciprocally in response to shaving forces. In several of these patents the same type of movement is disclosed for a guard bar. Reference is also made to our non prepublished copending EP-A-0 259 065 of which the present invention is a continuation and which discloses a blade assembly having pivotally mounted first and second blades which pivot and subsequently change the span of each blade in response to the amount of shaving force generated by the user. According to the invention there is provided a blade assembly comprising a blade supporting means for supporting first and second blades, and a guard bar, said blade supporting means comprising a first blade support adapted to support the first blade, said first blade support including pivotting means which allows movement of the first blade along a predetermined path to change the span of said first blade in response to pressures exerted during shaving, and said blade supporting means further including a second blade support adapted to support the second blade, said second blade support including pivotting means which allows movement of the second blade along a predetermined path to change the span of the second blade independently of the change in span of the first blade, wherein the pivotting means of the first blade support is in the form of a pivot pin preferably extending at least partially through the first blade support and further includes a leaf spring, and/or the pivotting means of the second blade support is in the form of a pivot pin preferably extending at least partially through the second blade support and further includes a leaf spring. The blade supporting means may further include a frame with a substantially flat bottom portion a front portion and a back portion. Both the front and back portions may extend upward from said bottom portion. A hollow central portion may be defined at either side by inner faces of said front and back portion. The front portion may include the guard bar which is preferably formed on the top of said front portion. The first blade support may be mounted on said bottom portion and may extend upward to support said first blade. The second blade support may be mounted on said bottom portion and may extend upward to support said second blade. Preferably a first and second stop depend from the sides of said frame to limit pivotal movement of said first and second blades. Desirably the shaving edges of the blades are substantially parallel to each other when not subjected to shaving forces. The leaf spring may project upward from the bottom portion. Shoulders may extend from said bottom portion of said frame to surround a major portion of the length of each of said leaf springs. The blades may be mounted on said blade supports by staking. The span of said first and second blades may vary between substantially 0.040 in. (0.1 cm) and substantially 0.090 in. (0.229 cm) in response to shaving pressure. The pivot pins preferably extend through receiving holes larger than said pins. It is desirable that the holes allow limited eccentric movement of said blade supports. According to another aspect of the invention there is provided a blade assembly comprising in combination: (a) a frame with an essentially flat bottom portion, a front portion and a back portion both portions extending upward from said bottom portion, a hollow central portion defined at either side by inner faces of said front and back portion, said front portion including a guard bar formed on the top of said portion; (b) a first blade support mounted on said bottom and extending upward to support a first blade, said blade support including pivotting means in the form of a pivot pin extending through said support which allows movement of the first blade along a predetermined path to change the span of said first blade in response to pressures exerted during shaving; and (c) a second blade support mounted on said bottom portion and extending upward to support a second blade, said blade support including pivotting means in the form of a pivot pin which allows movement of the second blade along a predetermined path to change the span of said second blade independent of the change in span of said first blade. Reference is now made to the accompanying drawings, in which: Figure 1 is a side view of a blade assembly according to our co-pending EP-A-0 259 065, partially in cross-section; Figure 2 is a plan view of the blade assembly shown in Figure 1; Figure 3 is a side view partially in cross-section of the blade assembly shown in Figures 1 and 2; and Figure 4 is a side view partially in cross-section of a blade assembly according to the present invention. In the drawings a razor blade assembly 10 is mounted upon a handle 19. The blade assembly 10 has razor blade supporting means in the form of a frame comprising a bottom portion 14, a front portion 15 and a back portion 12 with both the front and back portions upstanding from the bottom portion 14. The frame further includes an upper portion 13 which extends from the front portion 15 to the back portion 12. First and second stops 16 and 16' extend outward from opposite side portions 17. The blade supporting means also includes first and second blade supports in the form of fingers 21 and 21'; razor blades 24 and 24' are mounted on the fingers 21 and 21' respectively by means of stakes 25 and 25'. The fingers 21 and 21' are connected to the bottom portion 14 by means of leaf springs 22 and 22'. The movement of the leaf springs 22 and 22' is restricted by matching shoulders 23 and 23' which extend upward from the bottom portion 14. The leaf spring 22 is allowed to flex to "open" the space between guard bar 18 and blade 24; this is shown in Figures 1 and 2. The leaf spring 22' is allowed to flex to "open" the space between the blades 24 and 24'; this is shown in Figure 3. Conventionally, razor spans for each blade tend to vary between substantially 0.040 in. (0.1 cm) and substantially 0.065 in. (0.165 cm) depending upon the desired predetermined setting. According to a preferred embodiment each individual span can vary between substantially 0.040 in. (0.1 cm) and substantially 0.090 in. (0.229 cm) in response to the pressure exerted during shaving. The pressure acts sequentially against the first blade 24 and then the second blade 24' to increase the distance of the span by exerted forces against the biasing action of the springs 22 and 22'. As can be seen by reference particularly to Figures 2 and 3, each of the blades 24 and 24' are held in place by the stakes 25 and 25' which extend to the underlying fingers 21 and 21'. The blades 24 and 24' are staked separately. It should be noted that a cap is not shown in Figure 2 and that with both blades closed, the plan view of the razor shown in Figure 2 is similar to others currently available. As shown in Figure 2, the guard bar 18 extends toward the blades 24 and 24' and is connected to the bottom portion 14 by means of ribs 26. The embodiment according to the invention as shown in Figure 4 is similar to that shown in the other figures and like parts have been designated with like reference numerals. The fingers 21 and 21' in Figure 4 are provided with specific pivot points 30 and 30'. The pivot points 30 and 30' are in the form of pins extending through the fingers 21 and 21' from each side of the razor or a single pin extending transversely from one side of the blade assembly 10 to the other. In Figure 4, the blade 24 is shown in a closed position, whilst the blade 24' is shown in an open position. This embodiment restricts the compressibility of the springs 22 and 22' but also controls precisely the pivot arc of travel of each of the blades 24 and 24' via stops 16 and 16'. The fingers 21 and 21' can be provided with receiving holes to receive the pins. The hole are preferably larger than the pins and the holes preferably allow limited eccentric movement of the fingers 21 and 21'. Variations will readily suggest themselves to those skilled in the art. For example, a conventional spacer can be used as stop 16' for maintaining the minimum span of the second blade 24'. Also, the shoulders 23 and 23' can be extended to form abutments for fingers 21 and 21' to control the span. In particular the abutments may limit the maximum span of the blades 24 and 24'. It should be noted, that in response to shaving pressure the blades move only toward the rear to expand the span and return to their original non-pressurised position in the forward direction after shaving forces have been removed. This invention, therefore, provides a simple mechanical means of altering the skin flow of each blade of a multi blade system in response to pressure during shaving generated by the user. The blade assembly 10 shown in the drawings is part of a disposable razor wherein the assembly 10 is integral with the handle 19. However, the present invention is equally applicable to blade assemblies in the form of cartridges which can be removed from the handle.

Claims: A blade assembly (10) comprising a blade supporting means for supporting first and second blades(24,24'), and a guard bar (18), said blade supporting means comprising a first blade support (21) adapted to support the first blade (24), said first blade support (21) including pivotting means which allows movement of the first blade (24) along a predetermined path to change the span of said first blade (24) in response to pressures exerted during shaving, and said blade supporting means further including a second blade support (21') adapted to support the second blade (24'), said second blade support (21') including pivotting means which allows movement of the second blade (24') along a predetermined path to change the span of the second blade (24') independently of the change in span of the first blade (24), wherein the pivotting means of the first blade support (21) is in the form of a pivot pin (30) extending through the first blade support (21) and further includes a leaf spring 22, and/or the pivotting means of the second blade support (21') is in the form of a pivot pin (30') extending through the second blade support (21') and further includes a leaf spring (22'). A blade assembly (10) according to Claim 1, characterised in that the blade support means further includes a frame with a substantially flat bottom portion (14), a front portion (15) and a back portion (12), both portions extending upward from said bottom portion (14), a hollow central portion defined at either side by inner faces of said front and back portion (15,12), and said front portion (15) includes the guard bar (18) which is formed on the top of said front portion (15), and preferably the first blade support (21) is mounted on said bottom portion (14) and extends upward to support said first blade (24), and the second blade support (21') is mounted on said bottom portion (14) and extends upward to support said second blade (24'). A blade assembly (10) according to Claim 2, characterised in that a first and second stop (16,16') depend from the sides (17) of said frame to limit pivotal movement of said first and second blades (24,24'). A blade assembly (10) according to Claim 1, 2 or 3 characterised in that the shaving edges of the blades (24,24') are substantially parallel to each other when not subjected to shaving forces. A blade assembly (10) according to any one of Claims 2 to 4, characterised in that the leaf spring (22,22') projects upward from the bottom portion (14), and/or characterised in that shoulders (23,23') extend from said bottom portion (14) of said frame to surround a major portion of the length of each of said leaf springs (22,22'). A blade assembly (10) according to any preceding claim, characterised in that the blades (24,24') are mounted on said blade supports (21,21') by staking (25,25'). A blade assembly according to any preceding claim, characterised in that the span of said first and second blades (24,24') can vary between substantially 0.040 in. (0.1 cm) and substantially 0.090 in. (0.229 cm) in response to shaving pressure. A blade assembly according to any preceding claim, characterised in that the pivot pins (30,30') extend through receiving holes larger than said pins (30,30'). A blade assembly according to Claim 8, characterised in that said holes allow limited eccentric movement of said blade supports (21,21').

Inventors: FERRARO, FRANK A.
Applicants: WARNER-LAMBERT COMPANY
Application year: 1987
Main classification: B26B21
IPC codes: B26B21