U.S. patent application number 13/829575 was filed with the patent office on 2014-09-18 for tape dispenser.
The applicant listed for this patent is Geoffrey Joseph Ormerod. Invention is credited to Geoffrey Joseph Ormerod.
Application Number | 20140263528 13/829575 |
Document ID | / |
Family ID | 51523095 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140263528 |
Kind Code |
A1 |
Ormerod; Geoffrey Joseph |
September 18, 2014 |
Tape Dispenser
Abstract
A tape dispenser comprises a body supporting a blade having a
base, a point and two blade sides extending from the base to the
point, and a plate, the plate located in close proximity to the
blade, the blade and the plate each extending laterally with
respect to the longitudinal axis of the body and to the same side
of the body. The point of the blade is in the form of a spike, the
cross-section of the spike being less than the cross-section of the
blade, and the spike including a free end, the free end of the
spike including a tape engaging surface.
Inventors: |
Ormerod; Geoffrey Joseph;
(Newcastle-upon-Tyne, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ormerod; Geoffrey Joseph |
Newcastle-upon-Tyne |
|
GB |
|
|
Family ID: |
51523095 |
Appl. No.: |
13/829575 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
225/77 |
Current CPC
Class: |
B65H 35/008 20130101;
B65H 35/0026 20130101; Y10T 225/282 20150401 |
Class at
Publication: |
225/77 |
International
Class: |
B65H 35/00 20060101
B65H035/00 |
Claims
1. A tape dispenser comprising a body supporting a blade having a
base, a point and two blade sides extending from the base to the
point, and a plate, the plate located in close proximity to the
blade, the blade and the plate each extending laterally with
respect to the longitudinal axis of the body and to the same side
of the body, wherein the point of the blade is in the form of a
spike, wherein cross-section of the spike is less than the
cross-section of the blade, wherein the spike includes a free end,
the free end of the spike including a tape engaging surface.
2. A tape dispenser according to claim 1, wherein the tape engaging
surface is flat and substantially parallel with said body.
3. A tape dispenser according to claim 1, wherein the blade, the
point and the spike are formed in a unitary component and one face
of the spike is concave.
4. A tape dispenser according to claim 1, wherein a slanting
surface extends from an edge of the tape engaging surface to a wall
defining the concave face of the spike.
5. A tape dispenser according to claim 1, wherein the concave face
of the spike is defined by a curved wall.
6. A tape dispenser according to claim 1, wherein the concave face
of the spike is defined by a plurality of planar walls.
7. A tape dispenser according to claim 1, wherein the blade and the
spike include walls and the walls of the blade and the spike to one
side of the plate lie in the same plane, and the walls of the blade
and the spike to the other side of the plate lie on different
planes.
8. A tape dispenser according to claim 7, wherein the walls of the
blade and the spike proximate the plate lie in the same plane and
the walls of the blade and the spike distal from the plate lie on
different planes.
9. A tape dispenser according to claim 1, wherein the point is
located towards the centre of the blade.
10. A tape dispenser according to claim 1, wherein the blade sides
are straight.
11. A tape dispenser according to claim 1, wherein the blade sides
are curved.
12. A tape dispenser according to claim 1, wherein the spike
includes a part of the blade sides.
13. A tape dispenser according to claim 1, wherein the spike
includes a metallic element.
14. A tape dispenser according to claim 1, wherein the blade
extends in a direction substantially perpendicular to the body.
15. A tape dispenser according to claim 1, wherein at least a part
of the plate lies at an angle inclined towards the blade.
16. A tape dispenser according to claim 1, wherein the plate is a
spring plate.
17. A tape dispenser according to claim 16, wherein the part of the
plate inclined towards the blade extends at an angle of one of: the
range of 45 to 90 degrees; the range of 55 to 80 degrees; the range
of 60 to 75 degrees; the range of 63 to 72 degrees; and 67 degrees
to the longitudinal axis of the body.
18. A tape dispenser according to claim 16, wherein: the plate
includes removed portions.
19. A tape dispenser according to claim 18, wherein the removed
portions comprise slots extending inwardly from the outer edges of
the plate.
20. A tape dispenser according to claim 1, further including a
spacer adapted to, in use, engage with the tape of a reel of tape
on which the dispenser is mounted.
21. A tape dispenser according to claim 1, further including a
guide means, wherein the guide means includes side members adapted,
in use, to engage with the reel of tape and to limit lateral
movement of the dispenser with respect to the reel of tape.
22. A tape dispenser according to claim 1, wherein the dispenser
includes a stretchable flexible element, which in use attaches to
the body of the tape dispenser and extends around the reel of
tape
23. A tape dispenser according to claim 22, including at least one
enlarged portion so shaped and dimensioned as to co-operate with
and not pass through an opening in the said body of the dispenser.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a tape dispenser, which may
be of the type that attaches to a roll of tape, or of the type in
which a roll of tape is situated.
BACKGROUND OF THE INVENTION
[0002] Tape dispensers are long since known, and are generally
available in two different types, one being the type where a roll
of tape is mounted on a drum, and that drum is placed in a
carriage, which mounts a cutting blade, and the other being of the
type that is mounted on the roll of tape, and is moveable from roll
to roll as a user may require.
[0003] The dispensing of tape presents a number of problems. The
tape tends to adhere to itself, which can make lifting the free end
of the tape from the roll difficult. Also, known tape dispensers
often use blade having a plurality of upstanding serrations which
require the tape to be pulled downwards and sideways to tear a
piece of tape from the roll. The result of so attempting to tear
off a piece of tape is a tear line extending longitudinally along
the tape rather than laterally across.
[0004] Another problem associated with known tape dispensers is
that in order to pull more tape off the roll it is necessary to
lift the tape at a point between the blade of the dispenser, upon
which the free end of the tape is situated, and the point at which
the tape is released from adherence with the roll. Lifting the tape
in this manner can lead to the tape becoming crumpled.
[0005] Proposals have been made to solve some of these
problems.
[0006] U.S. Pat. No. 3,556,367 (Akira Ikeda) describes a device
that is held onto a roll of adhesive tape with a resilient bearing
member such as a spring, and which provides a guide and slot
through which the tape is drawn and cut by a blade.
[0007] WO2005/108258 (Pretorius) describes an accessory that is
attached to a roll of adhesive tape and held in place on the roll
by a spring. A slot is formed in the accessory through which the
tape is drawn and pulled to a cutting blade on one side of the
slot. After cutting, the adhesive side of the tape rests on a
support surface at the other side of the slot. The cutting blade
presents a point. The tape is brought down on the point and then
tears from the centre outwardly to either side of the point.
[0008] It is known from U.S. Pat. No. 6,681,830 and WO02055410 to
provide an irregular surface in a tape dispenser in order to reduce
adhesion. Both these documents refer to a dimpled surface.
[0009] However, none of the devices described provide a dispenser
that is satisfactory, and it would therefore be desirable to
provide an improved tape dispenser.
SUMMARY OF THE INVENTION
[0010] According to the invention there is provided a tape
dispenser comprising a body supporting a blade and a plate located
in close proximity to one another and each extending laterally with
respect to the longitudinal axis of the body and to the same side
of the body, wherein the blade presents a cutting edge.
[0011] The blade and the plate may lie substantially parallel one
another.
[0012] Advantageously, the blade is non-planar and preferably it
includes a point.
[0013] Preferably, the point of the blade is located towards the
centre of the blade.
[0014] In one embodiment of the invention the blade and the plate
extend substantially perpendicularly from the body. Advantageously,
a first part of the plate and the blade each extend in a direction
substantially perpendicular to the body. Preferably, a second part
of the plate extends at an angle forward of the axis of the first
part of the plate and towards the blade. Preferably, the second
part of the plate is curved or planar.
[0015] In another embodiment the plate is inclined with respect to
the longitudinal axis of the body.
[0016] Preferably, the plate or the second part thereof extends at
an angle in the range of 45 to 90 degrees to the longitudinal axis
of the body. More preferably, the plate or the second part thereof
extends at an angle in the range of 55 to 80 degrees to the
longitudinal axis of the body. Still more preferably, the plate or
the second part thereof extends at an angle in the range of 60 to
75 degrees to the longitudinal axis of the body. Yet more
preferably, the plate or the second part thereof extends at an
angle in the range of 63 to 72 degrees to the longitudinal axis of
the body. Most preferably, the plate or the second part thereof
extends at an angle of 67 degrees to the longitudinal axis of the
body.
[0017] Advantageously, the plate includes removed portions, which
may extend inwardly from the outer edges of the plate.
[0018] The plate is advantageously a spring plate. This provides
the advantage that the tape is pulled away from the blade when a
piece of tape has been successful separated from the reel.
[0019] The tape dispenser preferably includes a spacer adapted to,
in use, engage with the tape of a reel of tape on which the
dispenser is mounted.
[0020] The tape dispenser may include a guide means. The guide
means preferably includes side members adapted, in use, to engage
with the reel of tape and to limit lateral movement of the
dispenser with respect to the reel of tape.
[0021] The guide means may include at least one cross-member,
extending in a lateral direction with respect to the reel of tape,
and preferably across the reel of tape. The at least one
cross-member, with other parts of the guide means, defines an
opening through which, in use, the free end of the reel of tape is
drawn. The user draws a piece of tape of sufficient length through
the opening to provide a separated piece of tape of the desired
length.
[0022] In the case where the dispenser is mounted on a reel of
tape, pulling the tape off the reel has the effect of causing the
dispenser to slide on the reel of tape and rotate about the centre
of the reel. This due to the tape engaging with the cross-member
and exerting a force thereon sufficient to move the dispenser.
[0023] The tape dispenser preferably includes a base which mounts
the blade and the plate. The spacer may be mounted on the base. The
guide means may also be mounted on the base. Any or all of the
aforesaid may be fabricated as a plastics moulding, preferably as a
one-piece plastics moulding, for a plastic such as
polypropylene.
[0024] Advantageously, the dispenser includes a stretchable
flexible element, for example a length of elasticated thread, which
in use attaches to the body of the tape dispenser and extends
around the reel of tape. The element may include at least one
enlarged portion so shaped and dimensioned as to co-operate with
and not pass through an opening in the said body of the dispenser.
The body may include a slot in which the element is received.
[0025] The tape dispenser of the invention, whether in a form that
sits upon a reel of tape or the form comprising a carriage in which
the reel of tape sits, provides distinct advantages over the prior
art. Providing a pointed blade assists in ensuring that at the
point where a piece of tape is separated from the remainder of the
tape on the reel, the cut or tear is neat and does not run along
the length of the tape, as often happens with tape dispensers of
the art. The provision of a plate in conjunction with the blade,
and in particular where the plate is a spring plate, the blade is
able to separate the desired piece of tape from the tape on the
reel more easily. This is because the plate allows a force to be
exerted on the tape where the tape engages the blade that is much
greater downward component than is the case with typical tape
dispensers. Where the plate is sprung, immediately the tape is cut
that part of the tape that is still connected to the tape on the
reel but lies immediately behind the blade is lifted therefrom,
thereby making it easy for a user to grasp the free end of the tape
on the reel to separate further desired pieces of tape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In the Drawings, FIGS. 1 to 16 illustrate preferred prior
art tape dispensers, wherein:
[0027] FIG. 1 is a schematic representation of the tape
dispenser;
[0028] FIG. 2 is a rear end view of the tape dispenser illustrated
in FIG. 1;
[0029] FIG. 3 is a cross-sectional elevation on the axis B-B of the
tape dispenser shown in FIG. 2;
[0030] FIG. 4 is a side view of the tape dispenser illustrated in
FIG. 1;
[0031] FIG. 5 is a front end view of the tape dispenser illustrated
in FIG. 1;
[0032] FIG. 6 is a bottom plan view of the tape dispenser
illustrated in FIG. 1;
[0033] FIG. 7 is a perspective view of the tape dispenser
illustrated in FIG. 1 from above;
[0034] FIG. 8 is a schematic representation of the tape dispenser
illustrated in FIG. 1, attached to a roll of tape;
[0035] FIG. 9 is a schematic representation of another tape
dispenser;
[0036] FIG. 10 is a schematic representation of another tape
dispenser;
[0037] FIG. 11 is a plan view of the tape dispenser illustrated in
FIG. 10;
[0038] FIG. 12 is a schematic representation of the tape dispenser
illustrated in FIG. 10, viewed from the underside;
[0039] FIG. 13 is side view of the tape dispenser illustrated in
FIG. 10;
[0040] FIG. 14 is a schematic representation of another tape
dispenser;
[0041] FIG. 15 is a schematic representation of another tape
dispenser;
[0042] FIG. 16 is a schematic representation of another tape
dispenser;
[0043] and wherein preferred embodiments of a tape dispenser
according to the invention are shown, by way of example, in:
[0044] FIG. 17 illustrates an alternative embodiment of the
invention;
[0045] FIG. 17a is a cross-sectional side view of an alternative
embodiment of a point of the tape dispenser illustrated in FIG. 17;
and
[0046] FIG. 17b is front view of the point illustrated in FIG.
17a.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] Referring now to FIG. 1, there is shown a tape dispenser 1
of the type that is suitable for attachment to a reel of adhesive
tape. The tape dispenser 1 is formed of moulded plastics material,
and comprises a base plate 2, one end of which mounts an upwardly
extending blade member 8 having a point 9, and a downwardly
extending spacer member 6, which in use rests on the surface of the
reel of tape.
[0048] The other end of the base plate 2 mounts a spring plate 7
and guide 3, which comprises a cross-member 4 and side members 5,
5'. The guide 3 limits sideways movement of the dispenser 1 on the
reel of tape.
[0049] The cross-member 4, the side members 5, 5' and the rear edge
of the base plate 2 form an opening through which the free end of
the tape is passed.
[0050] In the illustrated example, the spring plate 7 is provided
with a non-uniform surface comprising a plurality of ribs extending
across the said surface. The non-uniform surface may be provided by
other elements, such as dimples for example. By providing the
spring plate with a non-uniform surface an adhesive tape will still
adhere thereto, but not as strongly as if the surface were smooth,
and hence releasing an adhesive tape from the surface of the spring
plate 7 is easier where the surface is non-uniform than when it is
uniformly smooth. However, adhesion of the tape to the spring plate
7 also depends on the properties of the material from which the
plate is formed. For some materials a smooth surface may function
satisfactorily.
[0051] The spacer member 6 serves to provide a second point of
engagement of the dispenser with the reel of tape. By providing the
spacer member 6 the dispenser is held in a stable position on the
reel of tape. In the case where no spacer member 6 is provided the
dispenser 1 may pivot about the reel when the user applies a force
to the tape on the reel to separate a piece therefrom.
[0052] As mentioned above, the blade 8 has a point 9 which, in the
illustrated example, is located substantially centrally. The
advantage of locating the point 9 of the blade substantially
centrally is that the user need pull the tape in only one direction
(downward) in order to separate a piece of the tape from the tape
on the reel, whereas with a blade that is flat and perhaps provided
with teeth, the tape must be pulled downward and sideways, which
often results in the tape tearing longitudinally rather than
laterally. This presents two problems. First, the piece of tape
separated from the reel is not of the desired shape. Second, the
free end of the tape on the reel is not square. This often leads to
the free end of the tape becoming detached from the plate
supporting the blade, and hence re-attaching itself to the
reel.
[0053] As can be seen from the Figures, the blade 8 is curved. It
has been found that when using a curved blade, rather than a
straight blade, the resulting tear is straighter and hence more
desirable.
[0054] The base plate 2 of the dispenser includes parts 2a and 2b
of a fastening system which comprises an element of elastic thread
having a stopper at each end thereof. A user fastens the dispenser
to a reel of tape by first placing the device 1 onto the reel with
the side members 5, 5' to either side of the reel. The user then
secures one end of the elastic thread in the part 2a with one
stopper engaging with the part 2a from the underside. The thread is
then passed over the top of the reel of tape with the thread
locating in the part 2b, which is in the form of a slot, down the
side and underneath the reel of tape and back to the part 2a, where
the other stopper engages with the part 2a from the upper side.
[0055] Once secured on the reel of tape, the free end thereof is
passed through the opening 3a. The tape is pulled backwards against
the cross-member 4, pulling tape off the reel and causing the
device 1 to move around the circumference of the reel until the
user ceases to pull backwards on the tape. The user then pulls the
tape towards the blade 8, and in so doing pulls the tape towards
the spring plate 7. With the tape engaged with the spring plate 7,
the piece of tape is held away from the reel so that it may easily
be detached by the user pulling the tape downward on the blade 8.
The point 9 pierces the tape which then tears from the position of
the point 9 to the outer edges of the tape. The spring plate 7
exerts a force on the tape which keeps it taught as the user pulls
downward on the tape against the blade. The combination of the
spring plate 7 and the close proximity of the blade 8 assist in
ensuring a neat separation of the piece of tape from the reel, as
does the substantially centrally located point of the blade. The
result is a separated piece of tape that is neatly cut. Also, the
free end of the tape is presented in such a way that another piece
thereof may be separated easily from the reel. This is because the
tape is held in place on the spring plate 7, and a short length of
tape extends beyond the end of the spring plate 7.
[0056] To remove tape from the reel subsequently the user grasps
the short length of tape extending between the spring plate 7 and
the blade 8 and lifts the tape upward. The user may then pull the
tape off the reel in the manner described above, and repeat the
process.
[0057] The tape dispenser 8 also includes a slot 10 which may be
adapted for cutting.
[0058] Referring now to FIG. 8, the tape dispenser 1 is illustrated
mounted on a reel of tape 11. As can be seen, the dispenser 1 is
attached to the reel of tape 11 by means of a length of elasticated
thread 12, which include enlarged portions 13a, 13b for engagement
in the opening 2a.
[0059] FIG. 9 illustrates a tape dispenser of the type including a
carriage 14 in which sits a drum 15 on which a reel of tape 16 is
mounted. The carriage 14 also mounts a spring plate 17 and a blade
18 having a point 19. As will be appreciated from the drawing, the
guide means 5 is not necessary in this embodiment, nor is any
flexible element needed as the reel of tape sits in the tape
dispenser, rather than the tape dispenser sitting on the reel of
tape.
[0060] Referring now to FIGS. 10 to 13, there is shown an
alternative embodiment of the invention. The embodiment illustrated
in FIGS. 10 to 13 functions in a substantially similar manner to
that illustrated in FIGS. 1 to 7. However, the base plate 2
includes walls 20, 21, 22 and 23 (and 20' to 23') extending
downwardly therefrom to each side of the base plate in pairs. The
distance between the walls of respective pairs 20, 20' to 22, 22'
correspond substantially to the widths of commonly available rolls
of tape. Also, the distance below the base plate 2 at which the
walls 20, 20' to 22, 22' terminate are selected to match the
respective diameters of commonly available rolls of tape, and are
determined such that the tape dispenser 1 sits on the roll of tape
substantially as shown in FIG. 8 in the way that spacer 6 does in
the embodiment illustrated in FIGS. 1 to 7. It will be noted that
the walls 23, 23' share a common axis with side members 5, 5', and
serve to maintain the dispenser 1 in the desired position on the
roll of tape.
[0061] The tape dispenser 1 illustrated in FIGS. 10 to 13 also
includes slots 24, 24' and 25, 25' to receive the thread 12. It
will be noted that this tape dispenser includes additional parts
2a' and 2b' arranged to receive the thread 12. The tape dispenser 1
may therefore be attached to a roll of tape in the manner
illustrated in FIG. 8, or the thread may be wrap around the tape
dispense twice, lying in all four slots 2a, 2a', 2b and 2b'.
[0062] The angle between the guide 3 and the longitudinal axis of
the body 2 may be approximately 140 degrees.
[0063] It can also be seen from FIGS. 10 to 13 that the spring
plate may be planar rather than curved and arranged at an angle of
approximately 67 degrees to the longitudinal axis of the body 2 or
the dispenser 1. The angle of 67 degrees may be adjusted, for
example, according to the height to the blade.
[0064] Referring now to FIG. 14, the tape dispenser 1 is moulded
from a relatively hard plastics material. This is advantageous in
that the point 9 of the blade 8 does not wear as quickly as where
the tape dispenser 1 is moulded from a softer plastics material.
However, it has been found that increasing the hardness of the
plastic material increases the springiness of the spring plate 7
causing the free end of the tape to rebound on to itself post
cutting. Since the object of the invention is to provide for more
convenient cutting of tape such a result is undesirable. The
springiness of the spring plate 7 may therefore be reduced by
forming the spring plate of a softer plastics material than the
blade part of the tape dispenser. However, it has also been found
that the springiness of the spring plate 7 may be reduced where the
spring plate is formed of the same harder plastics material as the
blade 8, and in fact the whole dispenser 1. The result may be
achieved by forming slots 7' or otherwise cutting away material at
the base of the spring plate 7.
[0065] Referring now to FIG. 15, the tape dispenser includes a
metallic element 9' having a shape corresponding to the shape of
the blade 8 and the point 9. The function of the metallic element
is to provide improved cutting, as the metallic element can be made
sharp and further they remain sharp for longer than plastics
materials. The metallic element may be attached to one surface of
the blade 8 or may be formed within the blade 8.
[0066] Polypropylene has been found to be a particularly suitable
material from which to manufacture the tape dispenser. Using this
material the spring plate provides the required amount of
springiness, without the need to form slots in, or otherwise cut
away material from the spring plate 7, whilst also providing a good
service life.
[0067] Experiments show that with the tape dispenser formed of
polypropylene, the spring plate 7 illustrated in FIGS. 10 to 13,
having a thickness of 0.5 mm and extending to a vertical height of
13 mm at an angle of 67 degrees, deflects by 2 mm towards the blade
8 and 2 mm towards the base plate 2, when the tape is pulled
downwards to engage the blade 8, and that the force required to
bring the tape into engagement with the blade 8 is between 115 to
200 grams. The experiments were performed on a number of different
samples, the variation in required force being accounted for by
manufacturing tolerances. The force exerted on the spring plate 7
is stored within the spring and released when the tape is cut. The
stored force is sufficient to pull the tape away from the blade and
hold it in a position above the blade 8, yet is not sufficient to
cause the tape to flick back onto itself.
[0068] FIG. 16 illustrates an alternative embodiment of the tape
dispenser where the metallic element 9'' is a rod embedded into the
blade 8 as illustrated in FIG. 16.
[0069] Referring now to FIG. 17, an embodiment having a point 9 of
modified shape is illustrated. In this embodiment rather than the
blade 8 coming to a point 9 through a gradual and continuous
reduction in thickness of the material from which the blade is
formed, the point 9 includes a part of reduced thickness forming a
spike 9a. The wall 9b of the spike 9a proximate the plate 7 in the
illustrated example lies on the same plane as the wall 8a of the
blade 8 that is proximate the plate 7, whereas the wall 9c of the
spike 9a distal from the plate 7 lies closer to the plate 7 than
the wall 8b of the blade 8. The wall 9c is concave, providing a
gradually reducing thickness of the spike 9a. The curved shape of
concave wall 9c is shown as a continuous curve. However, the
concave wall 9c could be formed by a plurality of planar
surfaces.
[0070] In the illustrated example of FIG. 17, the spike 9a does not
come to a sharp point, but has a substantially flat surface 9d. In
the illustrated example of FIG. 17, the flat surface 9d lies
substantially parallel to the body 2. The area of the flat
substantially flat surface 9d is sufficiently small that the spike
may still function to pierce tape, in particular in conjunction
with the other elements of the dispenser.
[0071] The effect of the spike is to create a hole in the tape as
the tape is pulled downward. The tape then tears sideways from the
so formed hole. It has been found that by forming the point 9 of
the blade as a spike a better separation of tape is accomplished.
Further, it has been found that by forming the point 9 into a spike
9a, the tip of the point can be somewhat thicker than the tip of
the point in FIG. 4 for example. This forms a stiffer point 9.
Still further, again looking at FIG. 4, in use, as the tape to be
separated from the reel is pulled downward over the point 9 of the
blade the tape engages with the curved part of the front of the
blade 8. The force exerted by the user is therefore reacted by
bending of the blade towards the plate 7. By forming the point 9
into a spike 9a, the initial piercing of the tape occurs more
rapidly and with less force applied. Once the tape has been
pierced, it is easier to tear.
[0072] FIG. 17a illustrates in detail the cross-section of an
alternative shape of spike 9a. The point 9 is formed into a spike
9a by reducing the thickness of blade 8 at the apex thereof, as
with the other embodiment illustrated in FIG. 17. However, instead
of the reduction in thickness being a gradual and continuous one,
the reduction is made in two steps. The first, reduction in
thickness of the blade is provided in the blade below the base of
the spike 9a, generating a slanting surface 9e. The spike 9a is
formed by a wall 9f extending upward and the wall 8a of the blade
8, the walls 8a and 9f being substantially parallel, and a slanting
surface 9g, and terminates in an end face 9d'. The end face 9d' is
smaller in surface area than the surface 9d in the other FIG. 17
embodiments, i.e. it is more pointed. Instead of the wall 9e being
a planar surface lying on an angle, the wall 9e could be
curved.
[0073] In FIG. 17, the sides 8c of the blade 8 are straight.
However, they may equally be curved as in the other figures in this
specification. The sides 8c of the blade need not be sharp. Where
the sides 8c of the blade are blunt, which is advantageous from the
perspective of safety, the sides 8c serve to guide the line of
tearing of the tape as the tear grows from the hole created by the
spike 9a.
* * * * *