Erasing liquid pen

A correction pen has a joining mechanism for joining together a front end portion (11) of a barrel (1), and a coupling portion (22) of a head member (2). The joining mechanism is constructed so that an inner cylindrical portion (22b) is pressed in a first coupling section (11a), an annular bead (2a) formed on an outer cylindrical portion (22a) squeezes a second coupling section (11b), and a bead (2c) formed on a step (22c) is pressed against the front end surface (1a) of the first coupling section when an annular ridge (1b) formed on the second coupling section (11b) is fitted in an annular groove (2b) formed in the outer cylindrical portion (22a). A ball holding tube (7) is provided with a ball housing bore (7b) and a connecting bore (7d) formed so that a low step is formed between the ball housing bore and the connecting bore. The edge of the tip of the ball holding tube is rounded. A head member is provided with a spring support portion (2f) for supporting a coil spring (8), provided with slots (2g). A cap releasing member (9) for releasing a cap (5) put on a head portion(222) of a barrel assembly (E) has operating portions disposed on the side surface of the cap so as to be in contact with an inclined portion (2h) of the head member.

TECHNICAL FIELD 
The present invention relates to a correction pen having the shape of a 
writing instrument, comprising a flexible barrel, a correction fluid 
prepared by dispersing a covering material such as white titanium pigment 
in an organic solvent and contained in the barrel, and a correction tip 
attached to the barrel, and capable of oozing out the correction fluid 
through the correction tip when the barrel is compressed between 
fingertips, and of being carried in a clothing pocket or the like. 
BACKGROUND ART 
Correction instruments which apply a white correction fluid to a paper 
sheet have been used to cover up incorrectly written marks. Recently, 
correction instruments respectively using color correction fluids of 
different colors have been marketed and used for marking as well as for 
writing. Demand for such correction instruments has greatly increased with 
the expansion of the application field. A correction instrument in an 
early stage of development was a simple bottle-type desktop correction 
instrument having a bottle containing a correction fluid therein, and a 
stick incorporated into the cap and provided at its free end with a brush. 
Such a simple bottle-type desktop correction instrument has been replaced 
with a squeeze correction instrument having a flexible container 
containing a correction fluid, a head cap for closing the container, and 
an application tip, capable of discharging the correction fluid through 
the application tip when the container is squeezed between fingertips, 
free from the possibility of spilling the correction fluid even if the 
container is laid sideways and capable of preventing the correction fluid 
from solidification even if the container is left uncapped. Recently 
various inventions and devices have been proposed to prevent the drying of 
the correction fluid on the application tip to avoid troublesome work for 
removing the solidified correction fluid from the inside of the cap and 
the application tip every time the squeeze correction instrument is used. 
As shown in FIG. 6, a correction instrument according to a previously 
proposed device disclosed in JP-U No. 62-29103 has a barrel assembly E 
comprising a flexible barrel 1 having a fluid tank portion 111 and a 
reduced front portion 11 of a diameter smaller than that of the fluid tank 
portion 111, having an open front end, a correction fluid 3 contained in 
the barrel 1, a stirring member 4 contained in the barrel 1, a head member 
2 having a coupling portion 22 fitted on the front portion 11 of the 
barrel 1, an application tip 66 serving as a front end portion of the head 
member 2 and as a component of a valve mechanism, a coil spring 8 
resiliently biasing the application tip 66 forward and an annular member 
10 having a spring bearing portion 10a. The annular member 10 is provided 
with a center hole 10c of a size allowing the application tip 66 to slide 
therein and allowing the correction fluid 3 to flow therethrough and a 
flange 10b held between the front end surface 1a of the front portion 11 
of the barrel 1 and a shoulder 22c formed in the head member 2. A cap 5 is 
detachably put on a head portion 222 of the barrel assembly E. 
With the expansion of the field of use of correction instruments as 
mentioned above, there have been proposed various correction instruments 
employing a ball capable of drawing lines of a fixed width and of writing 
letters as an application tip. One of those previously proposed correction 
instruments is disclosed in JP-U No. 5-80791. 
As shown in FIGS. 7A and 7B, a barrel assembly E included in a correction 
instrument disclosed in JP-U No. 5-80791 is assembled by putting a 
correction fluid 3 and a stirring member 4 in a barrel 1 having a fluid 
tank portion 111, and a reduced front end portion 11 of a diameter smaller 
than that of the fluid tank portion 111, having an open front end, putting 
a ball 6 in a ball holding tube 7 having an inside diameter slightly 
greater than the diameter of the ball 6 and having a front end 7a bent 
inward by swaging to keep the ball 6 therein, fitting the ball holding 
tube 7 in a front bore 2d formed in a head member 2, inserting a pressing 
member 88 in the ball holding tube 7 so that its front end is in contact 
with the ball 6, fitting an annular member 10 having a spring receiving 
portion 1a in a bore formed in the head member 2, extending a coil spring 
8 between the back end of the pressing member 88 and the spring receiving 
portion 10a of the annular member 10 to apply a pressure to the pressing 
member 88 so that the ball 6 projects partly from the front end of the 
ball holding tube 7, and fixedly mounting a coupling portion 22 of the 
head member 2 on the front end portion 11 of the barrel 1. A cap 5 is 
detachably put on a head portion 222 of the barrel assembly E. 
When using the prior art correction instrument according to the device 
disclosed in JP-U No. 62-29103, the pressure applied by fingertips to the 
flexible barrel is adjusted so that a desired quantity of the correction 
fluid is discharged through the application tip. When putting the cap of 
the correction instrument disclosed in JP-U No. 7-24470 on the body 
portion of the barrel assembly, air contained in the cap is compressed, 
and the compressed air flows into the barrel to maintain the interior of 
the barrel at an elevated pressure. When the application tip is pressed 
against a paper sheet or the like, the correction fluid is discharged 
automatically. Such, in outline, is the course of development of the 
correction instrument. The prior art correction instruments, practically, 
have both advantages and disadvantages, and there is still room for 
improvement in their performance and function. 
Although it is difficult to provide a correction instrument capable of 
exercising performance and function meeting all the requirements of the 
user, the present invention is intended to provide a correction pen having 
the shape of a writing instrument capable similarly to writing 
instruments, of being carried in a clothing pocket, and incorporating 
therein improvements in the airtightness and strength of the joint of a 
barrel and a head member, in performance to secure smoothness in 
discharging a fluid and correction work, and in function to enable a cap 
to be removed from the barrel quickly and easily. 
The barrel and the head member are joined together in an airtight fashion 
because the correction fluid contains an organic solvent. Most 
conventional correction instruments employ a joint structure like that 
shown in FIG. 6 or in FIGS. 7A and 7B in which the flange lob of the 
annular member 10 is held between the front end surface 1a of the barrel 
and the shoulder 22c of the coupling portion of the head member or employ 
an elastic packing to seal the joint. In view of the strength of the joint 
of the barrel and the head member, it is usual to use a screw joint by 
joining together the threaded front end portion of the barrel and the 
threaded coupling portion of the head member. However, a sufficiently 
strong screw joint cannot be formed if the barrel is formed by blow 
molding and, when the strength of the screw joint is particularly 
important, an adhesive must be used in combination with the screw joint, 
which requires troublesome work. Furthermore, the round screw joint of the 
barrel and the head member imposes restrictions on design. 
In a correction instrument employing a ball as an application medium, and a 
ball holder having, similarly to the tip of a ball-point pen, a ball seat 
in a ball housing bore, such as disclosed in JP-U No. 7-24470, a space 
around the ball is liable to be clogged with the fluid. If the correction 
instrument has a barrel which can be compressed to discharge the fluid 
forcibly to clean the tip, the correction instrument is able to be quickly 
restored to its normal condition. If the correction instrument is of a 
type which maintains the interior of the barrel at an elevated pressure to 
discharge the fluid automatically, it takes time to restore the clogged 
correction instrument to its normal condition, and hence special 
consideration is required to put the cap in an airtight condition on the 
head member of the barrel assembly. A front end portion of the ball 
holding tube has a small wall thickness, the feel of the contact with a 
paper sheet is deteriorated, and the correction fluid cannot be uniformly 
applied to marks to be erased if a ball of a small diameter is used to 
draw a narrow line by a correction instrument like the correction 
instrument proposed in JP-U No. 5-80791 shown in FIGS. 7A and 7B, in which 
the ball lies behind the front edge of the ball holding tube. 
To prevent the correction fluid from drying on the tip, the grasping force 
of the cap put on the head portion of the barrel assembly is higher than 
that of the cap of an ordinary writing instrument, and hence considerable 
force must be applied to the cap when putting the cap on and removing the 
same from the head portion of the barrel assembly. Therefore, it often 
occurs that the cap is put incompletely on the head portion of the barrel 
assembly and that the cap cannot be pulled properly and requires an 
unpleasant operation to pry the cap off the head portion of the barrel 
assembly. The correction pen of the present invention is provided with a 
clip on its cap and is intended to be carried in a pocket of clothes and 
hence the cap must be further firmly put on the head portion. 
SUMMARY OF THE INVENTION 
The present invention has been made in view of the foregoing circumstances. 
Means for solving the foregoing problems and the best mode for carrying 
out the same will be described hereinafter, based on the premise that a 
barrel assembly is assembled by constructing a tip assembly by putting a 
ball in a ball holding tube having a front end bent inward by swaging to 
hold the ball therein and pressing the ball forward directly or through a 
pressing member by a coil spring so that the ball projects partly from the 
front end of the ball holding tube, disposing the tip assembly in a front 
bore formed in a head member, and joining a coupling portion of the head 
member to a front end portion of a flexible barrel containing a correction 
fluid and stirring members, and a correction pen is completed by putting a 
cap on the head portion of the barrel assembly. 
To improve the airtightness and the strength of the joint of the barrel of 
the barrel assembly and the head member, the barrel has a fluid tank 
portion, a cylindrical first coupling section having an open front end, 
and a second coupling section having a circular cross section of a 
diameter greater than that of the first coupling section and smaller than 
that of the fluid tank portion or an elliptical cross section, extending 
between the fluid tank portion and the first coupling section, and 
provided with an annular ridge on its outer circumference. The coupling 
portion of the head member has an outer cylindrical portion to be fitted 
on the second coupling section of the barrel, having an inner 
circumference complementary to the outer circumference of the second 
coupling section, and is provided with an annular groove complementary to 
the annular ridge of the second coupling section of the barrel and an 
annular bead formed on the front side of the annular groove, having a 
diameter smaller than the outside diameter of the second coupling section 
and protruding toward the axis of the barrel. The coupling portion of the 
head member also has an inner cylindrical portion to be pressed in the 
first coupling section, having an outside diameter greater than the inside 
diameter of the first coupling section, and an annular bead formed in a 
step at the joint of the outer cylindrical portion and the inner 
cylindrical portion. A predetermined gap is formed between the back end 
surface of the head member and a shoulder of the barrel. The annular bead 
of the outer cylindrical portion of the head member squeezes the second 
coupling section of the barrel, and the front end surface of the first 
coupling section of the barrel is pressed against a bead formed at a 
stepped part of the head member when the head member is jointed to the 
barrel with the annular ridge of the second coupling section of the barrel 
fitted in the annular groove of the outer cylindrical portion of the head 
member. 
The annular bead of the outer cylindrical portion of the head member 
engages firmly around the second coupling section to prevent the radial 
play of the head member and the barrel relative to each other. The front 
end surface of the first coupling section of the barrel is pressed against 
the bead formed at the stepped part of the head member to prevent the head 
member from axial movement relative to the barrel. Accordingly, the joint 
is highly strong, is not subject to loosening, and is kept in a 
satisfactory airtight state even if an external force is applied violently 
thereto. 
To improve the mode of discharge of the correction fluid when correcting 
incorrectly written marks, writing letters or drawing lines, and to 
improve the feel of touch of the correction pen to the paper sheet or the 
like, the ball holding tube holding the ball, i.e., an application medium, 
is provided with a ball housing bore having a diameter slightly greater 
than that of the ball and extending from the front end of the ball holding 
tube in a length sufficient to enable the ball to be housed completely 
therein, a back bore, and a connecting bore having a diameter slightly 
smaller than that of the ball and connecting the ball housing bore to the 
back bore. The edge of the front end is rounded by barrel grinding after 
putting the ball in the ball housing bore and the front end of the ball 
holding tube is bent inward by swaging, and/or a spring support portion is 
formed in the interior of the inner cylindrical portion of the head member 
to support the coil spring extended in the tip assembly and is provided 
with slots to pass the correction fluid through the spring support 
portion. 
Thus, the space surrounding the ball is not clogged with the correction 
fluid because a small step is formed in the ball holding tube between the 
ball housing bore and the connecting bore. Since the correction fluid is 
able to flow through the spring support supporting the coil spring, the 
correction fluid can be discharged in smooth response to the fine 
adjustment of the compressive force applied to the barrel. Since the ball 
is able to withdraw into the ball housing bore during barrel polishing for 
rounding the edge of the front end of the ball holding tube, the contact 
between the ball and a grinding stone can be avoided and the edge of the 
front end of the ball holding tube can be properly rounded without 
deforming the ball, so that the ball holding tube slides smoothly on a 
paper sheet or the like when the correction pen is used. 
To improve and enable quick and simple removal of the cap from the barrel 
assembly, the cap is provided in its side wall with cap releasing members 
which are pressed toward the axis of the cap so as to slide along slopes 
or steps formed in the head member of the barrel assembly to release the 
cap from the head member of the barrel assembly. 
Thus, the cap need not be pulled to remove the same from the barrel 
assembly; the cap releasing members slide along the slopes or the steps 
when pressed toward the axis of the cap to release the cap firmly fitted 
on the head member quickly and easily. 
As mentioned above, according to the present invention, the barrel assembly 
is constructed by joining the head member to the barrel, the barrel 
assembly comprises a small number of parts, has a simple construction, is 
capable of containing the correction fluid containing an organic solvent 
in a satisfactory airtight fashion, has the strong joint of the head 
member and the barrel, has the space surrounding the ball and is not 
subject to clogging, ensures the smooth flow of the correction fluid from 
the fluid tank portion to the tip and enables the correction fluid to be 
discharged according to the finely adjusted pressure applied to the barrel 
assembly. The tip slides smoothly on a paper sheet or the like when 
correcting incorrect marks, writing letters and drawing lines. The cap can 
be easily removed from the barrel assembly by one hand, the correction pen 
can be safely carried in a clothing pocket of clothes similarly to a 
writing instrument, and the correction pen gives the same writing feel as 
that given by a writing instrument and can be manufactured at low cost.

BEST MODE FOR CARRYING OUT THE INVENTION 
The best mode for carrying out the invention will be described hereinafter 
with reference to the accompanying drawings, in which parts and portions 
like or corresponding to those of the previously described prior art 
correction instruments are designated by the same reference characters. 
FIG. 1A is a side view of a correction pen in a preferred embodiment 
according to the present invention and FIG. 1B is a longitudinal sectional 
view taken on line A--A in FIG. 1A. The correction pen embodying the 
present invention has a barrel assembly E constructed by joining together 
a front end portion 11 of a barrel 1 containing a correction fluid and 
stirring members 4, and a coupling portion 22 of a head member 2 holding 
in its front end bore 2d a ball holding tube 7 containing a ball 6, i.e., 
a tip assembly, and a coil spring 8 biasing the ball 6 toward the front 
end of the ball holding tube 7. A cap 5, provided in its side wall with a 
cap releasing member 9, is put on a head portion 222 of the barrel 
assembly E. 
As shown in FIGS. 2A and 2B, the fluid tank portion 111 has an elliptic 
cross section. The fluid tank portion 111 may be formed in any desired 
shape. The fluid tank portion 111 is provided in its side wall with 
shallow recesses 1d and grooves around the shallow recesses id for the 
fine adjustment of pressure to be applied to the fluid tank portion 111. 
As shown in FIG. 2B, the front end portion 11 of the barrel 1 has a 
cylindrical first coupling section 11a having an open front end 1a, and a 
second coupling section 11b having an elliptic cross section of a size 
greater than that of the cross section of the first coupling section 11a 
and smaller than that of the cross section of the fluid tank portion 111. 
The second coupling section 11b is provided on its outer circumference 
with an annular ridge (engagement part) 1b. A shoulder 1c substantially 
perpendicular to the second coupling section 11b is at the joint of the 
front end portion 11 and the fluid tank portion 111. The barrel 1 is 
formed of a resin, such as nylon 6, by blow molding. 
As shown in FIGS. 3A and 3B, the head member 2 is provided with a front end 
bore 2d to receive the ball holding tube 7 and has the coupling portion 22 
having a back end opening surface 2e. The coupling portion 22 has an outer 
cylindrical portion 22a to be fitted on the second coupling section 11b of 
the barrel 1, having an inner circumference complementary to the outer 
circumference of the second coupling section 11b, and provided with an 
annular groove (engagement part) 2b complementary to the annular ridge 1b 
of the second coupling section 11b of the barrel 1 and an annular bead 2a 
formed on its inner circumference at a position on the front side of the 
annular groove having a diameter smaller than the outside diameter of the 
second coupling section 11b and protruding inward. The coupling portion 22 
also has an inner cylindrical portion 22b to be pressed into the first 
coupling section 11a of the barrel 1, having an outside diameter greater 
than the inside diameter of the first coupling section 11a, and an annular 
bead 2c formed on a step 22c at the joint between the outer cylindrical 
portion 22a and the inner cylindrical portion 22b. A spring support 
portion 2f for supporting the coil spring 8, provided with a bore 
connected to the front end bore 2d is formed in the head member 2 so as to 
project into the interior of the inner cylindrical portion 22b. The spring 
support portion 2f is provided with axial slots 2g (FIG. 3B) facing the 
inner cylindrical portion 22b and communicating with the front end bore 
2d. If the resilience of the coil spring 8 is relatively high and the 
strength of the spring support portion 2f is thought to be insufficient to 
withstand the resilience of the coil spring 8, the spring support portion 
2f may be connected to the inner circumference of the inner cylindrical 
portion 22b by reinforcing ribs 2m (FIG. 3B). 
The head member 2 is provided on its outer circumference with a front 
coupling portion 2k, a back coupling portion 2j and an inclined portion 2h 
along which the cap releasing member 9 of the cap 5 slides. The front 
coupling portion 2k, the back coupling portion 2j and the inclined portion 
2h are the integral components of a cap holding and releasing means for 
holding the cap 5 on the head member 2 and releasing the same from the 
head member 2. 
It is important to select an appropriate material, such as PBT 
(Polybutylene Terephthalate) resin, for forming the head member because 
the annular groove 2b and the annular bead 2a of the coupling portion 22 
need to be forcibly removed from a mold when molding the head member 2 and 
to be shaped accurately, and the components of the cap holding and 
releasing means are formed on the outer circumference of the head member 
2. 
The present invention is intended to provide a pocketable correction pen 
capable of being carried, similarly to a writing instrument, in a clothing 
pocket, and the barrel 1 and the head member 2 must be firmly joined 
together so that the joint of the barrel 1 and the head member 2 may 
withstand unfavorable conditions which may be encountered by the 
correction pen. For example, it often occurs, when taking out a writing 
instrument from a breast pocket, that only the cap is taken out of the 
breast pocket and the barrel assembly remains in the breast pocket. In 
such a case the clothes will be smeared with ink if the writing instrument 
is a fountain pen or a marker that uses ink of a low viscosity. If things 
comes to the worst, cap cannot be properly put on the barrel assembly, the 
clip is broken or the joint of the barrel and the head member is broken. A 
crowded means of transportation is one of the causes of such trouble that 
may be readily thought of. Since the correction pen uses a correction 
fluid which is a special fluid containing an organic solvent, the 
reliability of the strength and airtightness of the joint of the barrel 
and the head member is an essential condition that should be satisfied. 
The barrel 1 and the head member 2 of the correction pen embodying the 
present invention are joined together as shown in FIG. 4. Referring to 
FIG. 4, when the head member 2 is joined to the barrel 1 with the annular 
ridge 1b of the second coupling section 11b of the barrel 1 fitted in the 
annular groove 2b of the outer cylindrical portion 22a of the head member 
2, a predetermined gap Q is formed between the back end surface 2e of the 
head member 2 and the shoulder 1c of the barrel 1, the inner cylindrical 
portion 22b of the head member 2 is fitted in the first coupling section 
11a of the barrel 1, the annular bead 2a of the outer cylindrical portion 
22a of the head member 2 squeezes the second coupling section 11b of the 
barrel 1 firmly, and the front end surface 1a of the first coupling 
section 11a of the barrel 1 is pressed against the bead 2c formed on the 
step 22c of the head member 2. 
Since the joint of the barrel 1 and the head member 2 in the barrel 
assembly E is thus formed, the annular bead 2a of the outer cylindrical 
portion 22a of the head member 2 squeezes the second coupling section 11b 
of the barrel 1 firmly, and the barrel 1 and the head member 2 are 
restrained from radial play relative to each other. Since the front end 
surface 1a of the front end portion 11 of the barrel 11 is pressed against 
the bead 2c formed on the shoulder 22c of the head member 2, the barrel 1 
and the head member 2 are restrained from axial play relative to each 
other. Since the gap Q is secured between the back end surface 2e of the 
head member 2 and the shoulder 1c of the barrel 1, any external force does 
not act on the front end portion 11 of the barrel 1 and the coupling 
portion 22 of the head member 2, even if a force is exerted violently on 
the front end portion 11 of the barrel 1 and the front end portion 11 is 
bent. Accordingly, the strong joint is not loosened and satisfactory 
airtightness of the joint is maintained. The size of the gap Q is 
dependent on the sizes and the shapes of the barrel 1 and the head member 
2. If the back end surface 2e of the head member 2 is brought into contact 
with the shoulder 1c of the barrel 1 by an external force, the coupling 
portion 22 is prized by leverage, whereby the condition of the joint is 
deteriorated. Therefore, the size of the gap Q must be determined so that 
the head member 2 may not be brought into contact with the shoulder 1c of 
the barrel 1 even if an external force is exerted on the head member 2. 
The prior art correction instrument employs the annular member having the 
flange held between the head member and the barrel, or the elastic packing 
to secure airtightness. However, any measures to prevent the radial and 
axial play of the head member and the barrel relative to each other are 
not incorporated therein, and therefore there is a possibility that the 
condition of the joint deteriorates with time to deteriorate the 
airtightness of the joint. The correction pen of the present invention 
secures the airtightness of the joint of the barrel 1 and the head member 
2, without providing any member corresponding to the annular member or the 
packing between the barrel 1 and the head member 2, by a double-joint 
structure constructed by pressing the inner cylindrical portion 22b of the 
head member 2 in the first coupling section 11a of the barrel 1 formed of 
an elastic material, such as nylon 6, by a press fit, and squeezing the 
second coupling section 11b of the barrel 1 by the annular bead 2a of the 
outer cylindrical portion 22a of the head member 2. Thus, the correction 
pen has a relatively small number of parts and a simple construction. 
The present invention employs the ball 6 as an application medium and 
incorporates improvements into the relation between the ball 6 and the 
ball holding tube 7 of the tip assembly fitted in the front end bore 2d of 
the head member, and the spring support portion 2f of the head member 2 
supporting the coil spring 8. The ball holding tube 7 is fabricated by 
processing a metal rod. As shown in FIG. 5, a back bore 7c is formed in a 
back portion of the metal rod, a front portion of the metal rod is tapered 
toward the front end so that a front edge 7a has a predetermined wall 
thickness, a ball housing bore 7b of a length long enough to receive the 
ball 6 entirely therein and of a diameter slightly greater than that of 
the ball 6 is formed in the metal rod from the front end thereof backward, 
a connecting bore 7d of a diameter slightly smaller than that of the ball 
6 is formed between the ball housing bore 7b and the back bore 7c, a ball 
6 is put in the ball housing bore 7b, the front end of the metal rod is 
reduced by swaging, and then the edge 7a of the front end of the metal rod 
is rounded by barrel polishing. 
Naturally, the ball holding tube 7 may be formed by processing a metal 
pipe. Essentially, the ball housing bore 7b and the connecting bore 7d are 
formed so that the step between the ball housing 7b and the connecting 
bore 7d is small to prevent the clogging of a space around the ball 6 due 
to the deposition of the pigment contained in the correction fluid 3 in 
the same space. Difficulty in handling the ball 6 individually during 
assembling work is avoided by combining the ball 6 and the ball holding 
tube 7, and measures are taken to prevent the deformation of the ball 6 by 
the grinding stone during barrel polishing for rounding the edge 7a of the 
front end of the ball holding tube 7. It is desirable to carry out the 
swaging process in two steps for swaging the front end in different 
swaging angles to round the edge 7a of the front end in an ideal shape. In 
this embodiment, the front end portion is swaged at a swaging angle of 
80.degree. first, and then the tip is swaged at a swaging angle of 
120.degree., not shown, to make the user feel a smooth movement of the tip 
of the correction pen on a paper sheet or the like. 
It is effective in preventing the drying of the fluid around the ball 6 to 
press the front end portion of the ball holding tube 7 against the ball 6 
by supporting the ball 6 from behind at a predetermined position with a 
rod inserted through the back bore 7c in the ball housing bore 7b during 
the swaging process for swaging the front end of the ball holding tube 7 
or to form the inner surface of the front end portion of the ball holding 
tube 7 in a shape, not shown, conforming to that of the ball 6 by 
hammering the ball 6 with a hammer rod inserted through the back bore 7c 
in the ball housing bore 7b after swaging the front end of the ball 
holding tube 7. 
Although the rounding of the edge 7a of the front end of the ball holding 
tube 7 is important to enable the tip of the correction pen to slide 
smoothly on a paper sheet or the like, the correction pen will be useless 
unless the correction pen is able to discharge the correction fluid 3 
smoothly. Therefore, it is important to secure the smooth flow of the 
correction fluid 3 from the barrel 1 into the tip assembly inserted in the 
front end bore 2d of the head member 2 by forming the ball housing bore 7b 
and the connecting bore 7d so that the step between the ball housing 7b 
and the connecting bore 7d is small to prevent the clogging of a space 
around the ball 6 and by forming the support portion 2f provided with the 
axial slots 2g (FIG. 3B), for supporting the coil spring 8 so as to 
project into the space surrounded by the inner cylindrical portion 22b. 
Thus, the correction fluid 3 is able to flow naturally from the fluid tank 
portion 111 of the barrel 1 into the space surrounded by the inner 
cylindrical portion 22b of the head member 2 and further through the axial 
slots 2g of the spring support portion 2f supporting the coil spring 8 
into the tip assembly When the correction pen is held with its tip 
assembly directed upward, the ball 6 is pressed against the inner surface 
of the front end portion having the edge 7a of the ball holding tube 7 by 
the coil spring 8 like a valve element pressed against a valve seat to 
close a valve, the fluid around the ball 6 remains around the ball 6 and 
all the fluid in the bore of the relatively large diameter in which 
capillarity is relatively low reverses into the fluid tank portion 111. 
Accordingly, it is important that the inner surface of the front end of 
the ball holding tube 7 is formed in a shape conforming to that of the 
ball 6 to prevent the fluid remaining around the ball 6 from drying, to 
discharge the fluid smoothly and to enable the tip of the correction pen 
to slide smoothly on a paper sheet or the like. 
Furthermore, the correction pen of the present invention enables removal of 
the cap 5 quickly and easily from the head portion 222 of the barrel 
assembly E. FIGS. 1A and 1B illustrate the relation between the cap 5 and 
the cap releasing member 9 by way of example. The cap 5 is provided with 
an inside cap formed integrally with the top wall thereof so as to isolate 
the end part of the head portion 222 and the tip assembly from the 
atmosphere and to be fitted in a stationary portion of the cap releasing 
member 9 to hold the cap releasing member 9 in place. The cap 5 is 
provided in its side wall with openings disposed directly opposite to each 
other, and push buttons connected to the stationary portion of the cap 
releasing member 9 are projected outside through the openings. The cap 5 
is provided at its open end portion with a holding part for holding the 
cap 5 on the head member 2. (Indication of parts other than principal 
parts by reference characters is omitted.) 
When the cap 5 is put on the head portion 222 of the barrel assembly E, the 
stationary portion of the cap releasing member 9 and the front coupling 
portion 2k of the head member 2 are engaged firmly, and the holding part 
formed in the open end portion of the cap 5 and the back coupling portion 
2j of the head member 2 are engaged firmly. Therefore, a considerably high 
force is necessary to pull off the barrel assembly E by holding the barrel 
assembly E and the head portion 222 and simply pulling, which is thus 
effective in preventing the separation of the barrel assembly E from the 
cap 5 in the pocket and the resultant smearing of clothes with the 
correction fluid. According to the present invention, the cap releasing 
member 9 has the push buttons projected outside through the openings 
formed in the cap 5 which slide along the inclined portion 2h of the head 
member 2 when pressed inward to release the cap 5 from the head member 2 
of the barrel assembly E. Thus, the cap 5 firmly held on the head member 2 
can be quickly and easily released from the head member 2. 
The relation between the cap 5 and the cap releasing member 9 is not 
limited to that employed in the embodiment. For example, it is possible to 
form a step instead of the inclined portion 2h in the head member 2, and 
each of the push buttons of the cap releasing member 9 may be provided 
with an inclined surface, not shown, that slides along the step of the 
head member. A cap releasing member (not shown) may be formed integrally 
with the cap. Since the cap can be released from the head portion simply 
by pressing the push buttons of the cap releasing member projecting from 
the side surface of the cap, the cap can be removed from the barrel 
assembly by one hand and hence the other hand can be used for other 
purposes.