There is disclosed a one-hand openable and closable umbrella which does not cause relative rotational movement and displacement between an inner shaft and an outer shaft. The inner shaft has a U-shaped groove extending in the lengthwise direction thereof and the outer shaft has a convex block provided inside a lower nest mounted on the top of the outer shaft. By the engagement of the convex block of the outer shaft with the U-shaped groove of the inner shaft, the inner and outer shaft neither turn nor displace relative to each other when the latter slides on the latter. Moreover, since a plastic sleeve is put on the upper end portion of the inner shaft inside a spring mounted thereon, any frictional force between the spring and the inner shaft and between the spring and an upper nest can be decreased, by which the umbrella can be smoothly opened and closed.

BACKGROUND OF THE INVENTION 
The present invention relates to a one-hand openable and closable umbrella 
which can be opened and closed with one hand. 
FIG. 9 shows a conventional umbrella of this kind which has previously been 
proposed by one of the inventors of this application (see Japanese Patent 
Publication No. 41201/86) and has a double shaft composed of an inner 
shaft 1a and an outer shaft 1b which are smoothly slidable relative to 
each other. A required number (usually eight) of main ribs 2 are pivotally 
secured at one end to the top of the inner shaft 1a so that they extend 
radially thereof at predetermined angular intervals 
(360.degree./8=45.degree. when the number of main ribs 2 is eight). A 
required number (equal to the number of main ribs, that is, eight) of 
auxiliary ribs 4 are pivotally secured at one end to the top of the outer 
shaft 1b so that they extend radially thereof at predetermined angular 
intervals (45.degree. when the number of auxiliary ribs is eight), and as 
indicated by 2a, they pivotally support at the other end the main ribs 2 
near the positions where the main ribs 2 are secured to the inner shaft 
1a. A handle 6a is mounted on the lower end portion of the outer shaft 1b 
and an auxiliary handle 6b is attached to the lower end of the inner shaft 
1a. A coiled spring 5 is mounted on the upper and portion of the inner 
shaft 1a so that it provides a force between the outer shaft 1b and the 
inner shaft 1a in a direction in which to cause the upper end portion of 
the outer shaft 1b to approach the upper end portion of the inner shaft 
1a. On the handle 6a there is provided a control button 7a as a releasable 
locking mechanism for temporarily inhibiting the relative sliding movement 
of the outer shaft 1b and the inner shaft 1a. When the control button 7a 
is depressed, the temporary inhibition of the relative sliding movement of 
the shafts is released. The relative sliding movement can be temporarily 
inhibited again in a state in which the positional relationship between 
the outer shaft 1b and the inner shaft 1a has been changed while the 
handle 6a has been brought down to the vicinity of the auxiliary handle 
6b, closing the main ribs 2 (a first state). 
When the umbrella is held in its folded state, the handle 6a is normally in 
contact with the auxiliary handle 6b. When depressing the control button 
7a with one finger of the hand holding the handle 6a so as to open the 
umbrella, the inner shaft 1a is slid down relative to the outer shaft 1b 
by the elastic force of the spring 5, by which the auxiliary ribs 4 act to 
spread out the main ribs 2, opening the umbrella. The umbrella can be used 
in such a state, but when it is desirable to fix the main ribs at their 
fully opened position on a windy day, for example, the auxiliary handle 6b 
mounted on the lower end portion of the inner shaft la is pulled down away 
from the handle 6a with a finger of the hand holding the umbrella, by 
which the umbrella is put in such a second state as shown in FIG. 5, in 
which the outer shaft 1b and the inner shaft 1a are locked to each other. 
In the case of closing the umbrella, the control button 7a is depressed 
with a finger of the hand holding the handle 6a, the tip of the outer 
shaft 1b is slightly pulled away from the tip of the inner shaft 1a under 
the action of the coiled spring 5 and the auxiliary ribs 4 are closed, by 
which the main ribs 2 are slightly moved in the direction to be closed. 
The coiled spring 5 is not so stiff, as mentioned previously; so that, by 
lightly pulling the handle 6a toward the auxiliary handle 6b which is 
pressed against an user's body, for example, the main ribs, slightly 
closed as mentioned above, are fully closed with ease, and hence the 
umbrella is folded up with the outer shaft 1b and the inner shaft 1a 
locked to each other. 
In this prior art example, however, the positions 2a of the auxiliary ribs 
4 supporting the main ribs 2 are relatively close to the inner shaft 1a 
(about 7 to 10 cm) when the umbrella is open, and consequently, in the 
case where the wind is high, the main ribs 2 and cloth spread thereon may 
become slack, making the umbrella unstable in its opened state. 
By locating the positions 2a away from the center of the umbrella, the main 
ribs 2 can be made stable in its opened state, but the auxiliary handle 6b 
further extends downwardly of the handle 6a accordingly, making the 
umbrella unhandy to use and unshapely. 
It is an umbrella shown in FIG. 10 to solve the above-mentioned defects 
(see Japanese Utility Model Public Disclosure No. 169116/89). This 
umbrella is provided with lateral auxiliary ribs 4a in addition to the 
auxiliary ribs 4 in the prior art example shown in FIG. 9. The outer ends 
of the lateral auxiliary ribs 4a pivotally support the main ribs 
substantially centrally thereof as indicated by reference, numeral 2b, and 
the inner ends are pivotally secured to the inner shaft 1a as indicated by 
reference numeral 4b. Furthermore, the lateral auxiliary ribs 4a are each 
pivotally supported by the upper end of the corresponding auxiliary rib 4 
at a position of about 1/3 of the entire length of the rib 4a from the 
inner end thereof as indicated by reference numeral 4c. With such an 
arrangement, the lateral auxiliary ribs 4a are substantially horizontal as 
shown when the main ribs 4 are fully opened. The spring 5 is shown to be 
in its contracted state, and its expanding elastic force is utilized for 
opening and closing the umbrella. The upper end of the spring 5 is fixed 
to the inside of a ferrule mounting member 8. 
When the control button 7a is depressed to open the umbrella, the spring 5 
is still contracted but, by its expanding elastic force, the main ribs 2 
starts to be spread out. At the time point when the main ribs 2 reach 
their fully opened position as depicted in FIG. 10, that is, when the 
lateral auxiliary ribs 4a assume their substantially horizontal position, 
the elastic force of the spring 5 acts effectively, by which the main ribs 
2 are pressed against the cloth tied thereto. At this time, the relative 
sliding movement of the inner shaft 1a and the outer shaft 1b is inhibited 
by a stopper 9b. 
A hole for locking the umbrella in its opened state needs only to be 
provided, if necessary. Where the umbrella is manufactured for use under 
special conditions, for example as a golf umbrella, the provision of such 
a hole is the inner shaft 1a will make the umbrella more stable when it is 
put up. 
The prior art examples described above both have a construction in which 
the inner and outer shafts are engaged with each other and they have an 
upper nest and a lower nest secured thereto, respectively, but no 
structure is provided for their engagement. With such a construction, 
while the umbrella is in use, the inner shaft and the outer shaft readily 
turn or displace relative to each other and under the action of an 
external force or due to abnormal handling of the umbrella by its user, 
but it does not matter usually. In the case of opening or closing the 
umbrella, however, there is a fear that its ribs are easily twisted, 
causing trouble in the opening or closing of the umbrella. Moreover, in 
the prior art examples the spring is directly put on the top end portion 
of the inner shaft above the upper nest. When the umbrella is opened and 
closed, any friction between the spring and the outside of the top end 
portion of the inner shaft is always caused by the expansion and 
contraction of the spring. Since the both are made of metal alone, their 
friction is very likely to make a harsh grating noise. Besides, their 
surfaces are liable to damage by their long-term friction, and since the 
user usually stands the umbrella with the ferrule downward, there is a 
fear that rain water flows between the inner shaft and the spring and 
causes the top end portion of the inner shaft and the inside of the spring 
to corrode, shortening the service life of the umbrella in its entirety. 
In the prior art examples, the inner shaft has a stopper provided thereon 
at an appropriate position and as the umbrella is opened, the outer shaft 
slides on the inner shaft to a predetermined position where the lower nest 
strikes against the stopper when the umbrella is fully opened. The stopper 
serves as a positioning means, but in practice, an appreciably severe 
shock is given to the umbrella whenever the lower nest bumps against the 
stopper. This is not comfortable to the user. If the user does not firmly 
hold the handle, the user may let go of the umbrella in spite of oneself. 
This is considerably dangerous. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a one-hand openable and 
closable umbrella of a construction which are free from relative 
rotational movement of the inner shaft and the outer shaft, and hence 
alleviates their friction and lengthens the service life of the umbrella. 
To attain the above object, the one-hand openable and closable umbrella of 
the present invention has a construction wherein the inner shaft has a 
U-shaped groove provided thereon to be extended in the length-wise thereof 
and a lower nest, mounted on the top end portion of the outer shaft, has a 
convex block on the inside thereof for engagement with the U-shaped groove 
of the inner shaft. The outer shaft is put on the inner shaft with the 
convex block of the lower nest received in the U-shaped groove. With this 
arrangement, when the outer shaft slides on the inner shaft, they neither 
turn nor displace relative to each other. This ensures smooth, shock-free 
opening and closing of the umbrella and, at the same time, prevents 
twisting of the umbrella ribs which may cause trouble in opening and 
closing of the umbrella. Hence, the umbrella of the present invention is 
long-lived. 
Moreover, a plastic sleeve is put on the top end portion of the inner shaft 
inside of the spring to effectively reduce any friction between the spring 
and the inner shaft. This prevents the generation of harsh grating noises 
by their friction and precludes the possibility of their corrosion which 
results from wear of their surfaces by friction. 
Furthermore, buffer means is mounted on the inner shaft at an appropriate 
position between the upper nest and the lower nest and a buffer spring is 
put on the inner shaft. This arrangement properly absorbs the shock which 
is applied to the lower nest when the umbrella is opened; accordingly, no 
unnecessary shock is applied to the entire structure of the umbrella. 
Hence, the umbrella of the present invention is handy to use and stout 
against an abnormal shock. 
In addition to the above mentioned structure, a sliding rod secured to the 
lower end of the inner shaft has also a convex block at an appropriate 
position on the inside thereof for engagement with the U-shaped groove of 
the inner shaft. This construction allows ease in positioning of the 
respective parts during assembly and causes the control button base and 
the rod to act as guides, preventing relative displacement of the inner 
and outer shafts. Hence, the umbrella of the present invention is handy to 
use and stable while in use. 
Moreover, two-stage assembling is adopted for the auxiliary handle which is 
fixed to the lower end of the outer shaft. By coupling the rod and the 
auxiliary handle to each other before the latter is attached to the outer 
shaft, there is no need of opening the umbrella during assembly. At first, 
the sliding rod is affixed to the lower end portion of the inner shaft, 
the handle is put on the rod and then fixed to the outer shaft just under 
the control button base mounted on the lower end portion of the outer 
shaft, after which the curved or bulged auxiliary handle is coupled to the 
lower end of the rod. Thus, the umbrella need not be opened during 
assembly. This permits easier fabrication of umbrellas.

DETAILED DESCRIPTION 
FIG. 1 is a schematic diagram showing an inner shaft 10 and an outer shaft 
20 and their associated parts in the present invention, from which the 
structural feature of the invention can be seen. The inner shaft 10 has a 
U-shaped groove 11 extending in the lengthwise direction thereof, whereas 
the outer shaft 11 has a convex block 22 provided thereon inside a lower 
nest 23 for engagement with the groove 11 of the inner shaft 10. The inner 
shalf 10 has a plastic sleeve 33 put on its top end portion 12 just above 
an upper nest 13. On the inner shaft 10 a buffer means 42 is mounted 
between the upper nest 13 and the lower nest 23 mounted at the top of the 
outer shaft 11. The buffer means 42 comprises a buffer ring 43, a fixed 
ring 43 fixedly mounted on the inner shaft 10 at one end of the buffer 
spring 45 and a strong ring 44 connected at the other end of the buffer 
spring 45 to slide on the inner shaft 10. 
FIG. 2 clearly shows, in section, the manner in which the convex block 22 
of the outer shaft 20 is received in the U-shaped groove 11 of the inner 
shaft 10. With this structure, where the outer shaft 11 slides on the 
inner shaft 10, they neither turn nor displace relative to each other and 
the umbrella can be opened and closed smoothly. In addition, since the 
umbrella ribs are not twisted, no trouble is caused in the opening and 
closing of the umbrella; therefore, the service life of the umbrella can 
be lengthened. 
FIG. 3 schematically shows the umbrella of the present invention in its 
folded state and FIG. 4 the umbrella in its opened state. According to the 
present invention, by inserting a plastic sleeve 33 in the inside of a 
spring 32 put on the top end portion 12 of the inner shaft 10 as shown, it 
is possible to prevent friction between the spring 32 and the inner shaft 
10 and between the spring 32 and the inner wall of the upper nest 13 when 
the umbrella is opened and closed. This prevents the generation of noises 
by their rubbing against each other and the wear of their surfaces which 
leads to their corrosion. Thus, the umbrella of the present invention is 
stoutly-built and long-lived. 
In the one-hand openable and closable umbrella of the present invention, 
buffer means 42 including a buffer spring 45 is mounted on the inner shaft 
10 at an appropriate position between the upper nest 13 and the lower nest 
23 so that it suitably absorbs the shock that is applied to the lower nest 
23 when the umbrella is opened. In case of opening the umbrella, the outer 
shaft 20 slides on the inner shaft 10 and the lower next 21 bumps against 
a stopper ring 44 of the buffer means 42. The stopper ring 44 is slidable 
on the inner shaft 10, and since the buffer spring 45 is held between the 
stopper ring 44 and a fixed ring 43 fixedly mounted on the inner shaft 10, 
it is possible to effectively absorb the shock that is applied to the 
lower nest 23 attached to the top of the outer shaft 20. Thus, the overall 
structure of this umbrella prevents the generation of unnecessary shocks, 
allows ease in using the umbrella and precludes the possibility of its 
structural breakdown by abnormal shocks. 
The above-described conventional one-hand openable and closable umbrella, 
such as shown in FIG. 10, has one curved or bulged auxiliary handle 
attached to the lower end of the inner shaft, and this is a conventional 
design which follows users' practice. It is true that the design of such a 
curved or bulged auxiliary handle makes the umbrella easy to hold and 
carry, but the design presents much difficulty in assembling of one-hand 
openable and closable umbrella. Referring now to FIG. 8 which is a 
schematic exploded view showing a conventional structure of such an 
auxiliary handle, a control button 83 is fitted in the skirt of a control 
button base 81, a ring 91 is fixedly mounted on an inner shaft 90 to stop 
the control botton base 81 and an auxiliary handle 92 is fixed to the 
inner shaft 90 below the fixed ring 91. The auxiliary handle 92 has, at 
its upper end, a sliding rod 921 on which a handle 82 is slidable. 
In assembling, the control button base 81 is fixed to the lower end of an 
outer shaft 80, the ring 91 is fixed to the inner shaft 90, the inner 
shaft 90 is inserted into the outer shaft 80 and the shaft assembly is 
coupled to an umbrella structure. In the assembling of umbrellas, the next 
step is most difficult. The auxiliary handle 92 and the handle 82 are 
assembled after assembling of umbrella ribs. The auxiliary handle 92 is 
coupled to the handle 82 after the latter is affixed to the lower end of 
the inner shaft 90. If the auxiliary handle 92 is first coupled to the 
handle 82, then the handle 82 cannot be affixed to the inner shaft 90 at a 
predetermined position because of the curved or bulged structure of the 
auxiliary handle 92. In this instance, the auxiliary handle 92 needs to be 
fixed to the lower end of the inner shaft 90; so that when the handle 82 
is affixed to the lower end of the inner shaft 90, the handle 82 is moved 
on the outer shaft 80 with the umbrella opened, after which the rod 921 
extending upward of the auxiliary handle 92 is fixed to the lower end of 
the inner shaft 90. Thus, the assembly is not efficient. 
In case of assembling respective parts of the umbrella, if the auxiliary 
handle 92 and the handle 82 cannot assembled with the umbrella closed, 
they can be assembled on a proper assembly line, because the cloth is not 
tied to umbrella ribs. With the conventional design of the auxiliary 
handle 92, it is necessary to fix the auxiliary handle 92 to the inner 
shaft 90 after opening the umbrella first and then pushing up the handle 
82 affixed to the lower end of the inner shaft 90. To open the umbrella is 
appreciably troublesome and the opened umbrella is considerably large in 
volume; hence, it consumes much space in assembling. This makes the 
arrangement of the assembly line difficult and the opened umbrella is very 
dangerous to workers during assembly. 
In the above-described conventional examples, the inner shaft 90 is 
cylindrical and the inner hole of the rod 921 of the auxiliary handle 92 
is also round. Accordingly, their positioning is difficult during assembly 
and they are likely to turn or displace relative to each other by any 
external force while the umbrella is used, with the result that the 
control button base 81 moved out of place, making the handling of the 
umbrella difficult. 
The above defects of the conventional one-hand openable and closable 
umbrella can be overcome by an embodiment of the present invention shown 
in FIG. 5, in which a sliding rod 30 and an auxiliary handle 40 are 
assembled in two stages. According to the present invention, the sliding 
rod 30 can be secured to the lower end of an inner shaft 10 before the 
former is inserted into the auxiliary handle 40. During assembly the 
umbrella need not be opened. After fixing the sliding rod 30 to the inner 
shaft 10, a handle 50 is put on the sliding rod 30 and fixed to the outer 
shaft 20 immediately below a control button base 21, followed by a step of 
coupling the auxiliary handle 40 to the lower end of the sliding rod 30, 
thus completing the assembly. 
According to the present invention, since the auxiliary handle 40 and the 
sliding rod 30 have two-stage structure as mentioned above, the handle 50 
need not be inserted in the lower end portion of the inner shaft 10 first 
in the case of coupling the sliding rod 30 to the lower end of the inner 
shaft 10, and the umbrella need not be opened during assembly, besides the 
sliding rod 30 can be fixed to the inner shaft 10 simply by moving up the 
outer shaft 20. Hence, the assembly line can be facilitated. Furthermore, 
the assembly line can be easily arranged. When the sliding rod 30 has been 
fixed to the lower end of the inner shaft 10, it is possible to couple the 
handle 50 on the sliding rod 30 and fix it to the skirt of the control 
button base 21 at the lower end portion of the outer shaft 20. By fixing 
the curved or bulged auxiliary handle 40 to the lower end of the sliding 
rod 30 finally, the assembly is completed. Thus, the afore-mentioned 
defects of the prior art examples can be overcome. 
FIG. 6 shows the sectional structure of the control button base portion in 
the present invention. As shown, the inner shaft 10 has a U-shaped groove 
11 extending in the lengthwise direction thereof and the lower end portion 
of the outer shaft 20, on which the control button base 21 is mounted, has 
a convex block 22 for engagement with the U-shaped groove 11. The convex 
groove 22 is received in the U-shaped groove 11 of the inner shaft 10 and 
serves as a guide when the outer shaft 20 slides on the inner shaft 10. 
With this structure, the outer shaft 20 and the inner shaft 10 do not turn 
or displace relative to each other while in use and the umbrella can be 
used with stability. 
FIG. 7 shows the sectional structure of the sliding rod 30 in the present 
invention. Since the sliding rod 30, which is fixed to the lower end 
portion of the inner shaft 10, also has an inwardly convex block 31 for 
engagement with the U-shaped groove 11 of the inner shaft 10 as shown, 
positioning of the sliding rod 30 is easy and accurate when it is coupled 
on the inner shaft 10. Moreover, once the umbrella has been assembled, the 
convex block serves as a guide for the sliding rod 30, the control button 
base 21 and the inner shaft 10 and prevents the inner shaft 10 and the 
outer shaft 20 from turning or displacing relative to each other. Thus, 
the umbrella can be used with stability. 
As will be appreciated from the above, the present invention brings about 
simple improvements on the inner shaft and auxiliary handle in the 
afore-mentioned prior art examples and attains the intended object, and 
hence possesses originality and inventiveness over the prior art examples.