U.S. patent application number 09/761653 was filed with the patent office on 2001-08-09 for frictional hinge device and a portable business machine into which the frictional hinge device is incorporated.
This patent application is currently assigned to Chuo Hatsujo Kabushiki Kaisha. Invention is credited to Hayashida, Takaaki, Uneme, Masato.
Application Number | 20010011407 09/761653 |
Document ID | / |
Family ID | 18536751 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011407 |
Kind Code |
A1 |
Uneme, Masato ; et
al. |
August 9, 2001 |
Frictional hinge device and a portable business machine into which
the frictional hinge device is incorporated
Abstract
In a frictional hinge device, an inequable strain distribution
within a synthetic resin is determined to be 15% or less so as to
increase a torque holding rate by 80% or more to tightly engage a
support block 20 with a metallic shaft 10. This eliminates
variations on a frictional torque with no substantial stickslip
phenomenon, abnormal noise and initial scratches accompanied when
pivotally moving the support block 20 relative to the metallic
shaft 10 so as to maintain a stable surface friction resistance
with good endurance for a long period of time.
Inventors: |
Uneme, Masato; (Nagoya-shi,
JP) ; Hayashida, Takaaki; (Nagoya-shi, JP) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS
1800 M STREET NW
WASHINGTON
DC
20036-5869
US
|
Assignee: |
Chuo Hatsujo Kabushiki
Kaisha
|
Family ID: |
18536751 |
Appl. No.: |
09/761653 |
Filed: |
January 18, 2001 |
Current U.S.
Class: |
16/342 |
Current CPC
Class: |
G06F 1/1681 20130101;
E05Y 2900/606 20130101; Y10T 16/5403 20150115; G06F 1/1616
20130101; Y10T 16/54038 20150115; Y10T 16/555 20150115; Y10T 16/557
20150115; E05D 11/082 20130101 |
Class at
Publication: |
16/342 |
International
Class: |
E05D 011/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2000 |
JP |
2000-8493 |
Claims
What is claimed is:
1. A frictional hinge device comprising: a shaft member having a
rotational axis as a rotational center; a support member which
rotatably supports said shaft member; said support member being
arranged so that said support member is rotatable relative to said
shaft member, said support member being formed by a synthetic resin
molded around said shaft member substantially in integral therewith
to produce a surface frictional resistance between said support
member and said shaft member due to a residual stress caused from a
shrinkage allowance appeared when said synthetic resin is
solidified; and an inequable strain distribution degree within said
synthetic resin being 15% or less in order to equalize a strain
distribution within said synthetic resin under the condition that a
strain within said synthetic resin corresponds to 80% or less of a
yield point when said synthetic resin is subjected to a tensile
experimental test. Where said inequable strain distribution degree
(%) is expressed by (.vertline.maximum strain (minimum strain)
average-strain.vertline.).times.100/(average strain) in which a
greater one is selected when compared said absolute value
.vertline.maximum strain.vertline. with said absolute value
.vertline.minimum strain.vertline..
2. The frictional hinge device as recited in claim 1, wherein said
synthetic resin is partly thickened or partly thinned in order to
equalize said strain distribution within said synthetic resin.
3. The frictional hinge device as recited in claim 1, wherein a
film injection gate or a multiple point injection gate is provided,
the former of which flows said synthetic resin smoothly and the
latter of which flows said synthetic resin dispersively when molded
around said shaft member in order to equalize said strain
distribution within said synthetic resin.
4. The frictional hinge device as recited in claim 1, wherein said
synthetic resin is dealt with a heat treatment at temperature of
0.8.times.Tg (.degree. C.) or higher after said synthetic resin is
molded around said shaft member in order to equalize said strain
distribution within said synthetic resin. Where Tg (.degree. C.) is
a vitreous transformation temperature when said synthetic resin
metamorphoses into a rubberized property.
5. The frictional hinge device as recited in claim 1, wherein an
equable control means is provided to determine mold conditions so
as to equally flow said synthetic resin around said metallic shaft
in order to equalize said strain distribution within said synthetic
resin.
6. The frictional hinge device as recited in claim 1, wherein a
least two means are combined among following items (a).about.(e) in
order to equalize said strain distribution within said synthetic
resin. (a) partly thickening or partly thinning said synthetic
resin, (b) providing a film injection gate to flow said synthetic
resin smoothly when molded around said shaft member, (c) providing
a multiple point injection gate to flow said synthetic resin
dispersively when molded around said shaft member, (d) dealing with
a heat treatment at a temperature of 0.8.times.Tg (.degree. C.) or
higher after said synthetic resin is molded around said shaft
member, and (e) determining molding conditions to equally flowing
said synthetic resin around said shaft member due to an equable
control means.
7. A portable business machine in which the frictional hinge device
as recited in any claims 1.about.6 is used to pivotably support a
display thereof so as to hold said display at desired angular
positions.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a frictional hinge device used to
pivotably support various lid plates at desired angular positions
including opening and closing positions, and concerns to a portable
business machine such as a laptop note type personal computer into
which the frictional hinge device is incorporated to hold a display
at the desired angular positions.
[0003] 2. Description of Prior Art
[0004] In this type of the frictional hinge device, a lid plate is
secured to a metallic shaft which is pivotably supported on a
holder block metal. The holder block metal clamps the metallic
shaft to produce a surface frictional resistance between the holder
block metal and the metallic shaft so as to hold the lid plate at
desired angular positions.
[0005] Although this makes a whole structure simple and contributes
to cost reduction, a certain quantity of grease is required for
lubrication between the holder block metal and the metallic shaft.
The grease becomes a likely cause of perimetric pollution around
the frictional hinge device.
[0006] In order to avoid these inconveniences, a shaft lock device
is disclosed by Laid-open Japanese Patent Application No. 7-26825
(laid-open on Jan. 27, 1995, assigned to Kabushiki Kaisha Kato
Spring Seisakusho ). This laid-open publication teaches that an
outer shaft is made of a synthetic resin and integrally molded with
an inner shaft. Due to a surface frictional resistance caused from
a thermal expansional difference between the inner and outer
shafts, the inner shaft is held at any desired angular positions
while permitting the inner shaft to pivot relative to the outer
shaft against the force of the surface frictional resistance
therebetween. Due to the surface frictional resistance, a display
is held at the desired angular positions in a laptop note type
personal computer.
[0007] In the shaft lock device disclosed by the Laid-open Japanese
Patent Application No. 7-26825, providing a surface roughness,
surface treatment and frictional coefficient are suggested as means
to determine the frictional torque between the inner and outer
shafts together with their diametrical dimensions.
[0008] However, this disclosure remains silent about qualitative
and quantitative analyses on a relationship between the inner and
outer shafts. This causes no smaller variations on the frictional
torque when the inner shaft pivotally moves relative to the outer
shaft. This also causes abnormal noise due to a stickslip
phenomenon when pivotally moving the inner shaft, thereby losing a
good endurance with a reduced frictional torque due to an
unacceptable amount of wear between the inner and outer shafts.
[0009] Therefore, the present invention has been made with the
above drawbacks in mind.
[0010] It is a main object of the invention to provide a frictional
hinge device which is inexpensive with no fear for perimetric
grease pollution and no abnormal noise accompanied with a stickslip
phenomenon with the least torque variations, and is capable of
maintaining a stable surface frictional resistance between a shaft
member and a support member for an extended period of time so as to
repeatedly hold the support member at desired angular positions
based on a substantially uniform surface frictional resistance.
SUMMARY OF THE INVENTION
[0011] With a frictional hinge device having a support member
rotatably supported by a shaft member, a support member is
integrally molded around the shaft member when a synthetic resin is
injected into a mold die in which the shaft member is placed
beforehand.
[0012] Due to the synthetic resin contracted by a residual stress
caused from a shrinkage allowance when solidified, the support
member tightly engages with the shaft member. This provides a good
surface frictional resistance therebetween. When the support member
is subjected to a frictional torque greater than the surface
frictional resistance, the support member pivots around the shaft
member relatively. When the support member is subjected to a
frictional torque less than the surface frictional resistance, the
support member is held at an appropriate angular position by the
surface frictional resistance.
[0013] With the synthetic resin molded around the shaft member, the
support member and the shaft member are assembled quickly with the
least manufacturing cost.
[0014] Thus, the support member tightly engages with the shaft
member due to the synthetic resin contracted by the residual stress
caused from the shrinkage allowance when solidified, and a strain
appears within the synthetic resin of the support member in
correspondence to the residual stress.
[0015] The inventors carried out experimental tests by paying their
attention to a relationship between a strain distribution and a
torque holding rate. As a result, the inventors found that the
torque holding rate falls rapidly to deteriorate the endurance when
the strain distribution comes inequable such a degree as to exceed
15% (referred to as "inequable strain distribution degree"
hereinafter).
[0016] The torque holding rate T (%) is expressed by the formula
below.
T (%)=(a torque measured after undergoing a heat deteriorating
experimental test or an endurance experimental test).times.100/(an
initial torque)
[0017] The strain distribution within the synthetic resin is
equalized so that the inequable strain distribution degree is 15%
or less. Where the inequable strain distribution degree (%) is
expressed by (.vertline.maximum strain (minimum strain)-average
strain.vertline.).times.100/(average strain) in which a greater one
is selected when compared the absolute value .vertline.maximum
strain.vertline. with the absolute value .vertline.minimum
strain.vertline..
[0018] In order to realize these requirements, the support member
is quality controlled based on a molding method, configuration,
post-treatment and molding conditions to produce a frictional hinge
device superior in endurance.
[0019] With the high and stable torque holding rate thus achieved,
a smoothness is imparted to the shaft member to avoid an
unfavorable coagulation against the synthetic resin to obtain an
appropriate frictional resistance between the shaft member and
synthetic resin. This also reduces frictional torque variations and
a stickslip phenomenon significantly with no abnormal noise induced
due to the stickslip phenomenon when the support member pivots
relative to the shaft member.
[0020] In order to equalize the strain distribution within the
synthetic resin, the synthetic resin is partly thickened or partly
thinned.
[0021] In order to also equalize the strain distribution within the
synthetic resin, a film injection gate or a multiple point
injection gate is provided, the former of which flows the synthetic
resin smoothly and the latter of which flows the synthetic resin
dispersively when the synthetic resin is molded around the shaft
member.
[0022] In order to further equalize the strain distribution within
the synthetic resin, the synthetic resin is dealt with a heat
treatment at a temperature of 0.8.times.Tg (.degree. C.) or higher
after the synthetic resin is molded around the shaft member. Where
Tg (.degree. C.) is a vitreous transformation temperature when the
synthetic resin metamorphoses into a rubberized property.
[0023] In order to furthermore equalize the strain distribution in
the synthetic resin, an equable control means is provided to
determine mold conditions so as to equally flow the synthetic resin
around the shaft member.
[0024] With at least two means combined among (a).about.(e) below,
the strain distribution within the synthetic resin is
synergistically equalized.
[0025] (a) partly thickening or thinning the synthetic resin,
[0026] (b) providing the film injection gate,
[0027] (c) providing the multiple point injection gate,
[0028] (d) dealing with the heat treatment at temperatures of
0.8.times.Tg (.degree. C.) or higher, and
[0029] (e) determining molding conditions to equally flowing the
synthetic resin around the shaft member due to the equable control
means.
[0030] With the frictional hinge device used to pivotably move a
display for a portable business machine, it is possible to hold the
display repeatedly at any desired angular position for an extended
period of time while insuring a stable frictional torque with the
least amount of wear between the shaft member and the support
member.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Preferred forms of the present invention are illustrated in
the accompanying drawings in which:
[0032] FIG. 1 is a perspective view of the frictional hinge
device;
[0033] FIG. 2 is a side elevational view of a metallic shaft of the
frictional hinge device;
[0034] FIG. 2a is a plan view of the metallic shaft of the
frictional hinge device;
[0035] FIG. 3 is a plan view of the frictional hinge device but
partly sectioned;
[0036] FIG. 3a is a side elevational view of the frictional hinge
device;
[0037] FIG. 4 is a perspective view of a laptop note type personal
computer into which the frictional hinge device is incorporated as
a business machine;
[0038] FIG. 5 is a graphical representation showing how an
inequable strain distribution degree changes depending on where a
strain gauge is attached;
[0039] FIG. 5a is a plan view of a support block showing where the
strain gauge is attached when a tensile experimental test is
implemented to seek a strain distribution;
[0040] FIG. 5b is a side elevational view of the support block
showing where the strain gauge is attached when the tensile
experimental test is implemented to seek the strain
distribution;
[0041] FIG. 6 is a graphical representation showing how a
relationship between the inequable strain distribution degree and a
torque holding rate;
[0042] FIG. 7 is a stress-strain curve represented by a synthetic
resin;
[0043] FIGS. 8.about.8e are schematic views showing various methods
how to equalize the strain distribution within the synthetic
resin;
[0044] FIG. 9 is an example representing a single point injection
gate used when injecting the synthetic resin around the metallic
shaft;
[0045] FIG. 9a is an example representing a film injection gate
used when injecting the synthetic resin around the metallic
shaft;
[0046] FIG. 9b is an example representing a multiple point
injection gate used when injecting the synthetic resin around the
metallic shaft;
[0047] FIG. 10 is a characteristic curve showing how the torque
holding rate and the inequable strain distribution degree changes
depending on a heat treatment temperature; and
[0048] FIG. 11 is a characteristic curve showing how the torque
holding rate and the inequable strain distribution degree changes
depending on equable control conditions used when molding the
synthetic resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] Referring to FIGS. 1 and 4, a frictional hinge device 1 is
incorporated into a laptop note type personal computer 30 (portable
business machine) to pivotally move a lid plate 31 on which a
liquid crystal display 32 is mounted. The lid plate 31 is adjusted
at any desired angular positions to insure a good view on the
liquid crystal display 32.
[0050] The frictional hinge device 1 has a metallic shaft (shaft
member) 10 which serves as a rotational axis of a rotational center
10a. The metallic shaft 10 is secured to the lid plate 31 of the
personal computer 30 to pivotally move in unison with the lid plate
31. A support block (support member) 20 is provided to pivotably
support the metallic shaft 10 relative to the support block 20. In
this instance, the support block 20 may be secured to the lid plate
31, and metallic shaft 10 secured to a main body of the personal
computer 30.
[0051] As shown in FIGS. 2, 2a, 3 and 3a, the metallic shaft 10 is
made from an age-hardened stainless steel (SUS), a mild steel, or a
high Si containing aluminum-based alloy in order to form a columnar
configuration. The metallic shaft 10 has a diameter-increased
section 11 (e.g., 5 mm in diameter) at a middle portion and
diameter-reduced sections 12, 13 (e.g., 4 mm in diameter) at right
and left end portions respectively. The left ended diameter-reduced
section 13 has a dowel 14 to connectedly interfit into the lid
plate 31.
[0052] On the other hand, the support block 20 is formed by a
synthetic resin (e.g., PAR: acronymized from polyarylate) which
tightly engages with an outer surface of the diameter-increased
section 11 of the metallic shaft 10 as shown in FIGS. 3 and 3a. In
this instance, the synthetic resin pellets are injected into a mold
die in which the metallic shaft 10 had been placed beforehand.
[0053] At a time when molding the synthetic resin around the
metallic shaft 10, the mold die is preheated to approx. 165.degree.
C. This produces a predetermined quantity of a surface friction
resistance between the support block 20 and the metallic shaft 10
due to a residual stress caused from a shrinkage allowance appeared
when the synthetic resin is solidified.
[0054] The frictional hinge device 1 holds the lid plate 31 at any
angular positions in relation to the main body of the personal
computer 30. For this reason, it is necessary to adjust the
frictional torque between the metallic shaft 10 and the support
block 20 when the torque is less than a predetermined value. While
it is necessary to provide a smooth pivotal movement with the
metallic shaft 10 when the frictional torque is greater than the
predetermined value.
[0055] An attention was focused on a strain distribution within the
synthetic resin of the support block 20 in correspondence to a
residual stress established therein. As shown in FIGS. 5a and 5b,
three columns of strain gauge pieces are attached to an outer
surface of the support block 20 in a circumferential direction so
as to measure strains at places denoted by {circle over (1)},
{circle over (2)} and {circle over (3)}.
[0056] As a result, a relationship between the places {circle over
(1)}, {circle over (2)}, {circle over (3)} and an inequable strain
distribution degree was found as shown in FIG. 5. Where the
inequable strain distribution degree (%) is expressed by
(.vertline.maximum strain (minimum strain)-average
strain.vertline.).times.100/(average strain) in which a greater one
is selected when compared the absolute value .vertline.maximum
strain.vertline. with the absolute value .vertline.minimum
strain.vertline..
[0057] The torque holding rate T (%) is expressed by the formula
below.
T (%)=(a torque measured after undergoing a heat deteriorating
experimental test or an endurance experimental test).times.100/(an
initial torque)
[0058] It is to be observed that upon measuring the strain
distribution, the number of the gauge pieces attached to the
support block 20 can be variedly changed as desired.
[0059] As an acceptable range of the inequable strain distribution
degree, a margin of .+-.15% is adopted from the linear relationship
as shown in FIG. 5. From this point of view, the inequable strain
distribution degree within the synthetic resin is controlled to be
15% or less. This is to insure the torque holding rate of 80% or
more as understood from a characteristic curve in FIG. 6. In order
to avoid the support block 20 from deforming disproportionately
greater, the measurements were done under the condition that the
strain within the synthetic resin corresponds to 80% or less of a
yield point (tensile yield strength) when the synthetic resin is
subjected to a tensile experimental test as shown in FIG. 7.
[0060] Means to control the inequable strain distribution degree
under 15% or less are shown in FIGS. 8.about.8e. These means are
contrived with an attention paid to the support block 20 formed in
a keyhole-shaped configuration as shown in FIG. 8. In the support
block 20 having the keyhole-shaped configuration, the strain tends
to decrease at a circular head portion (B), and tends to increase
at lateral side portions (A) and (C) so as to render the strain
distribution inequable.
[0061] (1) In order to reduce the inequable stress distribution
degree (15% or less) within the synthetic resin, the metallic shaft
10 is eccentrically located upward to thin the circular head
portion (B) as shown at (i) in FIG. 8a. Otherwise, the metallic
shaft 10 is eccentrically located downward to thicken the circular
head portion (B) as shown at (ii) in FIG. 8a.
[0062] (2) The circular head portion (B) is thinned with the
metallic shaft 10 located unchanged to remain concentrical as shown
at (i) in FIG. 8b. Otherwise, the circular head portion (B) is
thickened with the metallic shaft 10 located unchanged to remain
concentrical as shown at (ii) in FIG. 8b.
[0063] (3) A rib (Ri) is provided on the lateral side portions (A)
and (C) as shown at (i) in FIG. 8c. A mildly curved pad portion
(Ro) and a linear-contoured pad portion (Re) are provided on the
lateral side portions (A) and (C) respectively as shown at (ii) and
(iii) in FIG. 8c.
[0064] The ribs (Ri) can be provided on two corners of the lateral
side portions (A) and (C) as shown at (i) in FIG. 8d. Otherwise
four ribs (Ri) can be provided on four corners of the lateral side
portions (A) and (C) as shown at (ii) in FIG. 8d.
[0065] (4) The support block 20 is formed so that its cross section
is symmetrical in the up (right) and down (left) directions to
equalize the strain distribution. Due to the support block 20
having a circular cross section as shown in FIG. 8e. In this
instance, four jugs (Sp) are circumferentially provided on the
support block 20 at regular intervals so as to lock the support
block 20 from inadvertently rotating circumferentially.
[0066] In order to equalize the strain distribution, another means
are adopted under the circumstances that the inequable strain
distribution degree tends to increase in a single point injection
gate (Gt) as shown in FIG. 9. This is because the single point
injection gate (Gt) changes the solidified speed depending on
places of the synthetic resin due to the varied flowing lengths
running around the metallic shaft 10 as shown at an arrow (J) in
FIG. 9.
[0067] In FIG. 9a, a film injection gate (Gs) is provided instead
of the single point injection gate (Gt). In order to substantially
achieve the uniform solidified speed across the metallic shaft 10,
the film injection gate (Gs) has an axial length dimension
corresponding to that of the metallic shaft 10 to keep the flowing
lengths substantially uniform as shown at an arrow (K) in FIG.
9a.
[0068] In FIG. 9b, a multiple point injection gate (Gu) is adopted,
gates are dispersed so that the flowing lengths from each of the
dispersed gates are substantially the same as shown at an arrow (H)
in FIG. 9b.
[0069] Another means is further adopted to equalize the strain
distribution within the synthetic resin. This means is to deal the
synthetic resin with a heat treatment after the synthetic resin was
solidified. This means is adopted to relieve a directive effect
induced within the synthetic resin when injected into the mold die.
When the synthetic resin is solidified without relieving the
directive effect, a molecular directive strain appears within the
solidified synthetic resin. The heat treatment is done to relieve
the molecular directive strain.
[0070] In order to seek a heat treatment temperature so as to
moderate the molecular directive strain, a relationship between the
heat treatment temperature, the torque holding rate and the
inequable strain distribution degree is determined as shown in FIG.
10. The relationship between the heat treatment temperature and the
inequable strain distribution degree is labeled by legend L, and
the relationship between the heat treatment temperature and the
torque holding rate is labeled by legend M. Curves labeled by the
legends L and M invert upside down when the heat treatment
temperature is around 0.75.times.Tg (.degree. C.). By setting the
heat treatment temperature at 0.8.times.Tg (.degree. C.) or higher,
the inequable strain distribution degree is 15% or less with the
torque holding rate at 80% or more. Where Tg (.degree. C.) is a
vitreous transformation temperature when the synthetic resin
metamorphoses into a rubberized property.
[0071] An equable control means is adopted to equalize the strain
distribution to determine a relationship between the inequable
strain distribution degree and the torque holding rate by changing
equable control conditions (molding conditions). The results are
shown in FIG. 11 in which a left half region from a vertical line
(S) teaches an acceptable level range that the inequable strain
distribution degree is 15% or less with the torque holding rate at
80% or more. Within the acceptable level range, the synthetic resin
flows equally around the metallic shaft to substantially equalize
the strain distribution.
[0072] Upon equalizing the strain distribution within the synthetic
resin of the support block 20, at least two means can be combined
among the above-mentioned contrivances.
[0073] Namely, at least two items can be combined by selecting
among the following items (a).about.(d).
[0074] (a) Partly thickening or thinning the synthetic resin as
shown in FIG. 8.
[0075] (b) Providing the film injection gate or providing the
multiple point injection gate as shown in FIG. 9.
[0076] (c) Dealing with the heat treatment at temperature of
0.8.times.Tg (.degree. C.) or higher as shown in FIG. 10.
[0077] (d) Determining the molding conditions to equally flowing
the synthetic resin around the metallic shaft 10 due to the equable
control means as shown in FIG. 11.
[0078] Thus, the inequable strain distribution degree within the
synthetic resin is determined to be 15% or less so as to increase
the torque holding rate by 80% or more to tightly engage the
support block 20 with the metallic shaft 10. This eliminates
variations on the frictional torque with no substantial stickslip
phenomenon, abnormal noise and initial scratches accompanied when
pivotally moving the support block 20 relative to the metallic
shaft 10 so as to maintain the stable surface friction resistance
with good endurance for a long period of time.
[0079] In the embodiment of the invention, the PAR (polyarylate) is
used to the support block 20 with the diameter-increased section 11
as 5 mm in diameter and the diameter-reduced sections 12 as 4 mm in
diameter.
[0080] The PAR (polyarylate) is one of heat-resistant
non-crystallized synthetic resins with Tg as high as 190.degree. C.
The PAR (polyarylate) is suited to the support block 20 because the
PAR (polyarylate) does not fluctuate its bending elasticity (GPa)
significantly under the perimetric ambient temperature range in
which business machines are usually used. With the general
operating temperature range (e.g., -20 to +100.degree. C.), the
synthetic resins are selected in which Tg is 120.degree. C. or
higher.
[0081] On the other hand, the crystallized resins used in general
has bending elasticity (GPa) fluctuating greatly under the
operating temperature. When these crystallized resins are applied
to the support block 20, the crystallized resins can not impart an
appropriate frictional resistance with the metallic shaft 10 under
the operating temperature fluctuating greatly. This is a reason the
crystallized resins are not suited to the support block 20.
[0082] From the superior heat-resistant view point, the
crystallized synthetic resins are selected from the so-called
"super engineering plastic materials".
[0083] These crystallized synthetic resins are PAR (polyarylate),
heat-resistant PC (polycarbonate), PPS (polyphenylene sulphide),
PES (polyether sulfone), PEEK (polyether ether ketone) and the
like.
[0084] When PTFE (polytetrafluoroethylene) is added by 3% by weight
to the synthetic resin, the metallic shaft 10 was found to start
pivoting smoothly, thereby further reducing an amount of dust worn
between the metallic shaft 10 and the support block 20.
[0085] As an alternative, added to the above crystallized synthetic
resin is an organic- or inorganic-based antifriction medium (within
15% by weight) such as fluoro-based resin, olefine-based resin,
graphite, carbon fiber, talc, vitreous particles, molybdate
bisulfide, potassium titanate or the like.
[0086] As another alternative, added to the synthetic resin is
mineral, vitreous fiber, carbon fiber or the like within 40% by
weight so as to provide a sufficient mechanical strength with the
support block 20 when forming in integral with the metallic shaft
10.
[0087] It is to be noted that the outer surface of the metallic
shaft 10 may be polished to impart a smaller surface roughness (Ra)
therewith. However, when the surface roughness (Ra) is within the
range of 0.15.about.0.35 .mu.m, the metallic shaft 10 may be
remained unpolished.
[0088] It is to be observed that instead of the lid plate 31 of the
laptop note type personal computer 30, the frictional hinge device
1 may be applied to various lid plates for a copy machine, a
porcelain toilet, an automobile hatch and hood, carrier side plates
of trucks, windows of living houses and a keyboard of piano.
[0089] The frictional hinge device 1 can be applied to any article
in which a lid plate is held at any desired angular positions by
the surface friction resistance between the metallic shaft and the
support block.
[0090] While there has been described what is at present thought to
be preferred embodiments of the invention, it will be understood
that modifications may be made therein and it is intended to cover
in the appended claims all such modifications which fall within the
scope of the invention.
* * * * *