WO2021108477A1

WO2021108477A1 - Powered hair clippers including blade assemblies with skin guide surfaces having inwardly curved portions

Info

Publication number: WO2021108477A1
Application number: PCT/US2020/062132
Authority: WO
Inventors: Anas Jaber
Original assignee: Carefusion 2200, Inc.
Priority date: 2019-11-26
Filing date: 2020-11-25
Publication date: 2021-06-03

Abstract

A hair clipper includes a clipper body including a motor. A blade assembly is connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation. The blade assembly includes a blade housing having a skin guide surface that faces skin of a patient during operation. The skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

Description

POWERED HAIR CLIPPERS INCLUDING BLADE ASSEMBLIES WITH SKIN GUIDE SURFACES HAVING INWARDLY CURVED PORTIONS

CROSS-REFERENCE

[0001] This application claims the benefit of and priority to US Provisional Application

No. 62/940,618 filed November 26, 2019, titled Powered Hair Clippers Including Blade Assemblies with Skin Guide Surfaces Having Inwardly Curved Portions,” the details of which are incorporated by reference as if fully set forth herein.

TECHNICAL FIELD

[0002] The present specification generally relates to powered hair clippers and, more specifically, to powered hair clippers with blade assemblies with skin guide surfaces having an inwardly curved portion.

BACKGROUND

[0003] Hair clippers are provided for hair removal. Some hair clippers may be suitable for everyday use and some hair clippers may be suitable for more specialized uses, such as in preparation for a medical procedure. The hair clippers generally include a blade assembly that includes a housing and a blade that extends outwardly from the housing. The housing may include a surface that glides along the skin as hair is being removed using the blade. The surface that contacts the skin may be flat thereby providing a relatively large percentage of surface area in contact with the skin under normal operating conditions. This flat surface can also cause build-up of skin in the form of a hump in front of the blade.

[0004] There is a need for blade assemblies with guide surfaces having a curved portion that provides a space for the skin behind the blade to accumulate which can reduce a size of a hump in front of the blade and allow for more skin flatness in front of the blade during a hair removal operation.

SUMMARY

[0005] In one embodiment, a hair clipper includes a clipper body including a motor. A blade assembly is connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation. The blade assembly includes a blade housing having a skin guide surface that faces skin of a patient during operation. The skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

[0006] In another embodiment, a blade assembly releasably connects to a clipper body such that the motor moves a moveable blade of the blade assembly during operation. The blade assembly includes a blade housing that has a skin guide surface that faces skin of a patient during operation. The skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

[0007] In another embodiment, a method of using a hair clipper for hair removal from a skin area of a patient is provided. The method includes coupling a blade assembly to a clipper body of the hair clipper. The blade assembly includes a clipper body comprising a motor and a blade assembly connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation. The blade assembly includes a blade housing having a skin guide surface that faces skin of a patient during operation. The skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges. The blade assembly is operated to remove hair from the skin area.

[0008] These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0010] FIG. 1 is a perspective view of a hair clipper with charging station, according to one or more embodiments shown and described herein;

[0011] FIG. 2 is a side view of the hair clipper of FIG. 1 in use, according to one or more embodiments shown and described herein;

[0012] FIG. 3 is a perspective view of a blade assembly for use with the hair clipper of

FIG. 1 , according to one or more embodiments shown and described herein; [0013] FIG. 4 is a section view along line 4-4 of FIG. 3, according to one or more embodiments shown and described herein;

[0014] FIG. 5 is a diagrammatic illustration of a flat blade assembly simulating use, according to one or more embodiments shown and described herein;

[0015] FIG. 6 is a diagrammatic illustration of the blade assembly of FIG. 3 simulating use according to one or more embodiments shown and described herein;

[0016] FIG. 7 is a method of performing a hair trimming operation, according to one or more embodiments shown and described herein; and

[0017] FIG. 8 is another embodiment of a blade assembly, according to one or more embodiments shown and described herein.

DETAILED DESCRIPTION

[0018] Embodiments described herein are generally directed to powered hair clippers with blade assemblies including a blade housing including a skin guide surface having an inwardly curved portion. The inwardly curved portion of the skin guide surface curves inwardly toward a center of the blade housing between terminal edges at which the inwardly curved portion terminates. The terminal edges are each located near opposite outermost edges of the skin guide surface. As will be described in greater detail below, the inwardly curved portion provides a space into which skin can fill, which can reduce bunching of skin in front of a moving blade during a hair removal operation.

[0019] In some embodiments, the blade housing may further include a patterned rib array that reduces contact area with skin. The patterned rib array may be located on a base guide surface and provides a reduced skin contact area compared to the base guide surface itself. A reduced contact area can reduce friction and provide an improved hair removal experience. Each rib of the patterned rib array may include an individual rib guide surface having an inwardly curved portion. The rib guide surfaces together may form at least part of the skin guide surface. In other embodiments, there may be no rib array and the base guide surface may form the skin guide surface with the curved portion.

[0020] Referring to FIG. 1, a hair clipper 10 includes a clipper body 12 that provides a housing for components of the hair clipper, such as a motor (e.g., a rotary motor), which is illustrated schematically by element 14, and a user interface 16 that is used to control operation of the hair clipper 10. The clipper body 12 may further include a rechargeable battery (e.g., a lithium battery) that can be recharged using a charging station 18.

[0021] A blade assembly 20 is connected to the clipper body 12. The blade assembly 20 includes a blade housing 22 and a moveable blade 24 that extends outwardly from the blade housing 22. In some embodiments, the blade assembly 20 may be removable from the clipper body 12 and be disposable. In other embodiments, the blade assembly 20 may be a permanent part of the clipper body 12 and may not be intended to be removable without damage to the hair clipper 10. For removable blade assemblies 20, there may different blade assembly types, such as general purpose blade assembly for body hair, a neuro blade assembly for scalp and other thick, course hair and a sensitive blade assembly for perineal/sensitive areas. The blade assemblies may be intended for a single use.

[0022] The blade assembly 20 includes the moveable blade 24 and a stationary blade 26 that both extend outwardly from a corner 28 of the blade housing 22 defining a blade cutting direction in the direction of arrow 30 (FIG. 2). The blades 24 and 26 have teeth that provide a comb-like shape across a width of the blades 24 and 26 defining a width direction in the direction of arrow 32 that is perpendicular to the blade cutting direction. The motor 14 reciprocates the moveable blade 24 in the width direction relative to the stationary blade 26 via a linkage 34 in order to cut hair located between the teeth.

[0023] Referring to FIG. 3, the blade housing 22 includes a skin guide surface 36 that is located at a skin engagement end of the hair clipper 10. The skin guide surface 36 faces the skin during a trimming operation. As can be seen, the skin guide surface 36 has an inwardly curved portion 40. The inwardly curved portion 40 curves inwardly toward a center C (FIG. 4) of the blade housing 22 between terminal edges 42 and 44 at which the inwardly curved portion 40 terminates on opposite edges. The terminal edges 42 and 44 are each located near opposite outermost edges 46 and 48 of the skin guide surface 36 with one of the outermost edges 46 located at the blades 24, 26 and the other outermost edge 48 at an opposite trailing side 50 of the blade housing 22. Planar edge areas 52 and 54 are located between the terminal edges 42, 44 and the opposite outermost edges 46 and 48. The planar edge areas 52 and 54 may be located in a same plane to define a planar guide plane P for the blades 24 and 26. Referring briefly to FIG. 2, in some embodiments, the cutting direction 30 (and the guide plane P) may be at an angle 0 (e.g., between about 135 and about 145 degrees) that is oblique to a central axis A that passes through a base portion 53 of the blade housing 22. [0024] In some embodiments, the blade housing 22 includes an array of ribs 74. The ribs 74 extend along a width of a base guide surface 56. In particular, the patterned array of ribs 74 include outermost ribs 74a and 74b that extend along opposite sides of the blade housing 22. The outermost ribs 74a and 74b extend the entire length of the guide surface 56. Interior ribs 74c-74j are located inboard of the outermost ribs 74a and 74b providing spaced regions 84 and 86 where no ribs are present. In some embodiments, the spaced regions 84 and 86 may each be at least about 10 percent of the width of the guide surface 56, such as at least about 15 percent, such as at least about 20 percent of the length of the guide surface 56. In this regard, an inboard region 88 of the guide surface 36 may have a higher rib density per unit width than adjacent outboard regions 90 and 92.

[0025] Interior ribs 74c and 74j extend along sides of the inboard region 88 and each extends the entire length of the base guide surface 56. Inboard of ribs 74c and 74j are central ribs 74d-74i. The central ribs 74d-74i extend only a portion of the length of the base guide surface 56, intersecting or beginning at terminal edge 42 of the inwardly curved portion 40 and terminating before terminal edge 44. As can be seen, ribs 74d and 74i are longer than ribs 74e- 74h, which are the shortest ribs 74. Each of the ribs 74 may have a length (in the X-direction) that is much greater than their width, such as at least about 2 times their width, such as at least about 3 times their width, such as at least about 4 times their width, such as at least about 5 times their width. Space is provided between the ribs 74d-74i to provide a somewhat undulating pattern of ribs and valleys. The outboard regions 90 and 92 includes round ribs 100 and 102 in the form of arcs. The round ribs 100 and 102 may each intersect their respective outermost rib 74a and 74b at opposite ends.

[0026] The patterned array of ribs 74 may be formed by any suitable method, such as by etching, molding and/or machining. A suitable material may be acrylonitrile butadiene styrene (ABS). In some embodiments, the patterned array of ribs may be formed separately from the glade housing and attached thereto (e.g., by welding, adhesive, etc.). In other embodiments, the patterned array of ribs may be formed monolithic with the blade housing, such as by molding the blade housing and the plurality of ribs together. In embodiments where the patterned array of ribs are formed separately from the blade housing, different patterns of the array of ribs may be interchangeable and removably connected to the housing to provide different and selectable friction profiles. While use of ribs are described above, the skin guide surface 36 with inwardly curved portion may be used with any other suitable rib pattern, such as straight ribs or no ribs. [0027] Referring to FIG. 4, a cross-sectional side view of the blade housing 22 is illustrated to highlight the inwardly curved portion 40 of the skin guide surface 36. As described above, the blade housing 22 includes the skin guide surface 36. The skin guide surface 36 is formed, in part, by individual guide surfaces 58 of the ribs 74. The skin guide surface 36 has the inwardly curved portion 40 that curves inwardly toward the center C of the blade housing 22 between the terminal edges 42 and 44 at which the inwardly curved portion 40 terminates. The terminal edges 42 and 44 are each located near opposite outermost edges 46 and 48 of the skin guide surface 36 with one of the outermost edges 46 located at the blades 24, 26 and the other outermost edge 48 at an opposite side 50 of the blade housing 22. As shown, the terminal edges 42 and 44 may be substantially parallel to the outermost edges 46 and 48. The planar edge areas 52 and 54 are located between the terminal edges 42, 44 and the opposite outermost edges 46 and 48.

[0028] The inwardly curved portion 40 may be in the shape of a circular arc segment and may have a radius of curvature r that may be constant from terminal edge 42 to terminal edge 44. The radius of curvature r may be between, for example, 110 mm and 150 mm and extend between the terminal edges 42 and 44 a distance di of at least about 50 percent (e.g., at least about 60 percent, at least about 70 percent, at least about 80 percent, at least about 90 percent, such as about 95 percent) of a distance d2 between outermost edges 46 and 48 which define the total length of the skin guide surface 36. In some embodiments, the distance di may be between about 20 mm and about 25 mm and the distance d2 may be between about 22 mm and about 26 mm. In some embodiments, the radius of curvature r may provide a maximum recess at the innermost location of between about 0.5 and about 0.6 mm away from the guide plane P defined by the planar edge areas 52 and 54. The ribs 74 may have about the same radius of curvature as the inwardly curved portion 40.

[0029] Without wishing to be bound by theory, the radius of curvature r is selected to reduce skin hump in front of the blades 24, 26 thereby reducing the probability of nicking and scraping of the skin during a hair removal operation. The skin hump occurs because the normal reaction of the skin’s flexibility and elasticity attempts to inhibit the blades 24, 26 to sink into the skin, which causes the skin to bulge to a radius of curvature of around 90- 110 mm under a load of between about three to four newtons using a flat skin contact surface. The amount of bulge can depend on a number of factors, however, such as skin age and location. Typically, the more fatty cells underneath the skin, the more curved the skin becomes. Further, the amount of bulge can depend on amount of load applied to the blade housing 22. For example, the weight of clipper body alone can generate a force of about one newton, which can create a radius of curvature of around 150 mm using a flat skin contact surface. Generally, the larger the load, the greater the skin hump, which can create an increased risk for skin abrasion.

[0030] Referring to FIGS. 5 and 6, a test was conducted to compare a skin hump size in front of the blades 24, 26 using a flat skin contact surface with no inwardly curved portion (FIG. 5) and using the shape of the blade housing 22 described above with inwardly curved portion 40. As represented by FIG. 5, use of the blade housing 110 with flat skin contact surface 112 causes the skin 114 to collect or hump at area 116 in front of the blade housing 110 with the blade housing 110 under a load of about four newtons. The slope of the area 116 can be visually detected and can be measured using, for example, a digital protractor 118. As represented by FIG. 5, use of the blade housing 22 with inwardly curved portion 40 under the same load causes the skin 114 to hump within a space 120 that is provided by the inwardly curved portion 40, which reduces the hump size in front of the blade housing 22.

[0031] Further testing was conducted using both human operators and a robotic arm using simulated human skin, such as polydimethylsiloxane (PDMS). Using a robotic arm can allow the load applied to the blade housing to be controlled using sensors and feedback programming, which can maintain an average load of between about three newtons and four newtons, such as around an average of about 3.1 newtons over a given amount of trials and different skin surface contours. Use of human application of force can allow for testing under real world conditions. It was found using human application of force that use of a blade housing with curved portion, as described herein, tended to reduce an average number of clusters produced on the simulated human skin over the testing. Referenced in the Table below, a nick is a small scratch of limited length/area on the skin surface that may occur using only a portion of the blade and a scrape is a wider scratch of limited area over a larger part of the blade. A cluster can be an array of nicks and scratches over a larger area of the skin surface that can occur as the blade is moved over the skin surface. Clusters, in particular, can create uncertainty as to whether a particular surgical operation will occur after the hair removal process due to the larger area of skin surface damage and irritation. The Table below illustrates some results from testing of a hair trimmer with curved housing as described herein compared to a commercially available blade housing having no curved portion as described herein on the same type of simulated human skin using human application of force. The results below are averaged over nine shaved areas (nine trial areas).

Table

[0032] As can be seen, the blade housing with flat skin facing surface had nearly three times more clusters, which is the most severe category of the three categories. Average nicks and scrapes were closer to equal over the trials. Of course, test results are dependent on a number of factors such as force applied, technique and simulated skin type and conditions. The Table above is provided to show that, for a limited number of trials, an average amount of clusters was lower using the blade housing with curved portion than the commercially available flat blade housing.

[0033] Referring to FIG. 7, a method 200 of using the hair clipper for hair removal from a skin area of a patient may include coupling the blade assembly 20 to the clipper body 12 of the surgical clipper 10 at step 202. The blade assembly 20 includes, as described herein, the blades 24, 26 and the guide surface 36 with the inwardly curved portion 40. The guide surface 36 and the inwardly curved portion 40 are placed against the skin area, and the blade 24 is operated through the body 12 to remove hair from the skin area of the patient at step 204. At step 206, under a load placed on the blade housing, the skin bulges into the space 120 that is provided by the inwardly curved portion 40 thereby reducing a hump of skin located in front of the blades 24, 26 at step 206.

[0034] As described herein, the body 12 of the surgical clipper 10 is configured to electronically operate the blade 24. The body 12 includes the enclosure housing an electrical motor and a battery, which battery is configured to be rechargeable through coupling of the body 12 to a charging adaptor 18. The body 12 of the surgical clipper 10 further may include a charge indicator configured to indicate a low battery level of the battery below a predefined threshold. The method may include triggering an alarm through the charge indicator of the low battery level, coupling the body to the charging adaptor, and recharging the battery. The alarm may be a visual, audio, or tactile alarm. Such a visual alarm may be an LED light that may, for example, red to indicate the low battery level.

[0035] As discussed above, in some embodiments, the base guide surface may form the skin guide surface with inwardly curved portion without use of the ribs. Referring to FIG. 8, a blade housing 210 includes many of the features described above, except that a skin guide surface 212 is provided with an inwardly curved portion 214 without use of ribs.

[0036] In the embodiments described herein, use of the inwardly curved portion of the skin guide surface can reduce a development of a skin hump in front of the blades during a hair trimming operation. This reduction of skin hump is accomplished by the shape of the inwardly curved portion directing the skin into the space provided by the inwardly curved portion 40. Such reduction of skin hump aids to reduce a risk of skin clusters that could lead to surgical site infections and aids in the agility and maneuverability of the hair clipper on the skin area.

[0037] Embodiments can be described with reference to the following numbered clauses, with preferred features laid out in the dependent clauses:

[0038] Clause 1. A hair clipper comprising a clipper body comprising a motor; and a blade assembly connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

[0039] Clause 2. The hair clipper of clause 1, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

[0040] Clause 3. The hair clipper of clause 2, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

[0041] Clause 4. The hair clipper of clause 3, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane. [0042] Clause 5. The hair clipper of clause 4, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane.

[0043] Clause 6. The hair clipper of any one of clauses 1-5, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.

[0044] Clause 7. The hair clipper of any one of clauses 1-6 further comprising an array of ribs that define the skin guide surface.

[0045] Clause 8. The hair clipper of clause 7, wherein the array of ribs have a radius of curvature.

[0046] Clause 9. The hair clipper of any one of clauses 1-8 comprising a base guide surface that defines the skin guide surface.

[0047] Clause 10. The hair clipper of any one of clauses 1-9, wherein the blade assembly is removably connected to the clipper body.

[0048] Clause 11. A blade assembly that releasably connects to a clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising: a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

[0049] Clause 12. The blade assembly of clause 11, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

[0050] Clause 13. The blade assembly of clause 12, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

[0051] Clause 14. The blade assembly of clause 13, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane.

[0052] Clause 15. The blade assembly of clause 14, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane. [0053] Clause 16. The blade assembly of any one of clauses 11-15, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.

[0054] Clause 17. The blade assembly of any one of clauses 11-16 further comprising an array of ribs that define the skin guide surface.

[0055] Clause 18. The blade assembly of clause 17, wherein the array of ribs have a radius of curvature.

[0056] Clause 19. The blade assembly of any one of clauses 11-18 comprising a base guide surface defines the skin guide surface.

[0057] Clause 20. A method of using a hair clipper for hair removal from a skin area of a patient, the method comprising: coupling a blade assembly to a clipper body of the hair clipper, the blade assembly comprising: a clipper body comprising a motor; and a blade assembly connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges; and operating the blade assembly to remove hair from the skin area.

[0058] Clause 21. The method of clause 20 further comprising applying a pressure against the skin area using the blade assembly and bunching skin within a space provided by the inwardly curved central portion thereby reducing gathering of skin in front of the blade assembly.

[0059] Clause 22. The method of clause 20 or 21, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

[0060] Clause 23. The method of clause 22, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

[0061] Clause 24. The method of clause 23, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane. [0062] Clause 25. The method of clause 24, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane.

[0063] Clause 26. The method of any one of clauses 20-26, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.

[0064] For the purposes of describing and defining the present disclosure, it is noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc.

[0065] It is noted that recitations herein of a component of the present disclosure being

"configured" in a particular way, to embody a particular property, or to function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is "configured" denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

[0066] For the purposes of describing and defining the present disclosure it is noted that the terms “substantially” and “approximately” and “about” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “approximately” and “about” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0067] Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including, but not limited to, embodiments defined in the appended claims.

[0068] It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present disclosure, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

Claims

1. A hair clipper comprising: a clipper body comprising a motor; and a blade assembly connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

2. The hair clipper of claim 1, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

3. The hair clipper of claim 2, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

4. The hair clipper of claim 3, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane.

5. The hair clipper of claim 4, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane.

6. The hair clipper of claim 1, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.

7. The hair clipper of claim 1 further comprising an array of ribs that define the skin guide surface.

8. The hair clipper of claim 7, wherein the array of ribs have a radius of curvature.

9. The hair clipper of claim 1 comprising a base guide surface that defines the skin guide surface.

10. The hair clipper of claim 1, wherein the blade assembly is removably connected to the clipper body.

11. A blade assembly that releasably connects to a clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising: a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges.

12. The blade assembly of claim 11, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

13. The blade assembly of claim 12, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

14. The blade assembly of claim 13, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane.

15. The blade assembly of claim 14, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane.

16. The blade assembly of claim 11, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.

17. The blade assembly of claim 11 further comprising an array of ribs that form the skin guide surface.

18. The blade assembly of claim 17, wherein the array of ribs have a radius of curvature.

19. The blade assembly of claim 17 comprising a base guide surface that defines the skin guide surface.

20. A method of using a hair clipper for hair removal from a skin area of a patient, the method comprising: coupling a blade assembly to a clipper body of the hair clipper, the blade assembly comprising: a clipper body comprising a motor; and a blade assembly connected to the clipper body such that the motor moves a moveable blade of the blade assembly during operation, the blade assembly comprising a blade housing having a skin guide surface that faces skin of a patient during operation; wherein the skin guide surface has an inwardly curved central portion that curves inward from opposite terminal edges; and operating the blade assembly to remove hair from the skin area.

21. The method of claim 20 further comprising applying a pressure against the skin area using the blade assembly and bunching skin within a space provided by the inwardly curved central portion thereby reducing gathering of skin in front of the blade assembly.

22. The method of claim 20, wherein the opposite terminal edges of the inwardly curved central portion are spaced from opposite outermost edges of the skin guide surface.

23. The method of claim 22, wherein a first planar edge area is located between a first outermost edge and a first terminal edge and a second planar edge area is located between a second outermost edge and a second terminal edge.

24. The method of claim 23, wherein a planar guide plane passes through the first planar edge area and the second planar edge area, the inwardly curved central portion being recessed inwardly from the planar guide plane.

25. The method of claim 24, wherein the inwardly curved central portion is recessed a maximum distance of between about 0.5 mm and about 0.6 mm from the planar guide plane.

26. The method of claim 20, wherein the inwardly recessed central portion has a radius of curvature of between about 110 mm and about 150 mm.