Blade assembly featuring variable span

According to this invention a blade assembly is created featuring pivotally mounted first and second blades with pivot and subsequent change the span of each blade in response to the amount of shaving force generated by the user.

FIELD OF THE INVENTION 
This 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. 
BACKGROUND OF THE INVENTION 
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 is 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 razor frame 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 moveable components in various combinations. U.S. Pat. No. 
4,516,320 issued May 14, 1985 to Anthony J. Peleckis 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. 
U.S. Pat. No. 4,443,939 issued to Vincent C. Motta and Ernest F. Kiraly on 
Apr. 24, 1984 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. 
U.S. Pat. No. 4,069,580 issued to Cyril A. Cartwright et al. issued Jan. 
24, 1978 and U.S. Pat. No. 4,409,735 also issued to Cartwright et al. on 
Oct. 18, 1983 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 U.S. Pat. No. 
4,587,729 issued May 13, 1986 being the latest, describes a blade assembly 
with blades which are individually biased move linearly reciprocally in 
response to shaving forces. In several of these patents, Jacobson also 
teaches the same type of movement for a guard bar. 
SUMMARY OF THE INVENTION 
According to this invention a blade assembly is created featuring pivotally 
mounted first and second blades with pivot and subsequent change the span 
of each blade in response to the amount of shaving force generated by the 
user.

DETAILED DESCRIPTION OF THE INVENTION 
This can be seen by reference to the drawings and particular FIGS. 1 and 3, 
a razor blade assembly 10 is mounted upon a handle 19. The blade assemby 
has 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. An 
upper portion 13 shown here as a frame extends from the front to the back 
portion and stops 16 and 16' extend outward from side portion 17. 
Again referring to FIG. 3, blades 24 and 24' are mounted upon fingers 21 
and 21' respectively by means of stakes 25 and 25'. The fingers 21 and 21' 
are connected to the bottom of the blade assembly housing 14 by means of 
leaf spring 22 and 22'. The movement of the leaf spring is restricted by 
matching shoulders 23 and 23' which extend upward from the bottom of 14 of 
each blade assembly 10. In the embodiment shown, the leaf spring is 
allowed to flex to "open" the space between guard bar 18 and blade 24 (as 
shown in FIGS. 1 and 2 and between blade 24 and blade 24' as shown in FIG. 
3). 
Conventionally, razor spans for each blade and to vary between 0.040 and 
0.065 in. depending upon the desired predetermined setting. According to 
this invention each individual span can vary between 0.040 and 0.090 in. 
in response to the pressure exerted during shaving. The pressure acts 
sequentially against the first and then the second blade 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 FIGS. 2 and 3, each of the blades 
24 and 24' are held in place by stakes to the underlying fingers 21 and 
21', of necessity, are staked separately. 
As can be seen in FIG. 2, the razor appears visually similar to any of the 
disposable razors. It should be noted that the cap is not shown in FIG. 2 
but with both blades closed, the plan view of this razor is similar to 
others currently available. As shown therein, the guard bar 18 extends 
toward the blades 21 and 21' and is connected to the bottom of the razor 
frame 14 by means of ribs 26. 
While only a single embodiment is depicted in the drawings, variations were 
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 second blades 24'. Also, shoulders at 23 and 23' can be extended 
to form abutments for fingers 16 and 16' to control the span defining 
biasing movement. 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 nonpressured position in the forward direction after 
shaving forces have been removed. This invention, therefore, provides a 
simply mechanical means by altering the skin flow of each blade of a multi 
blade system in response to pressure curing shaving generated by the user.