U.S. patent application number 09/858684 was filed with the patent office on 2001-12-27 for electronic device.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Mochida, Norihiro, Nakamura, Toshikazu.
Application Number | 20010054949 09/858684 |
Document ID | / |
Family ID | 18652534 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010054949 |
Kind Code |
A1 |
Mochida, Norihiro ; et
al. |
December 27, 2001 |
Electronic device
Abstract
A positive thermistor element is supported by being clamped by
first and second resilient contact members that are opposed to each
other so as to be disposed along a diagonal and first and second
positioning protrusions that are opposed to each other so as to be
disposed along the other diagonal of the positive thermistor
element. The first resilient contact member is located toward the
periphery of the positive thermistor element from the second
positioning protrusion and the second resilient contact member is
positioned toward an inner portion of the positive thermistor
element from the first positioning protrusion.
Inventors: |
Mochida, Norihiro;
(Shiga-ken, JP) ; Nakamura, Toshikazu; (Shiga-ken,
JP) |
Correspondence
Address: |
KEATING & BENNETT LLP
Suite 312
10400 Eaton Place
Fairfax
VA
22030
US
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
Nagaokakyo-shi
JP
|
Family ID: |
18652534 |
Appl. No.: |
09/858684 |
Filed: |
May 16, 2001 |
Current U.S.
Class: |
338/232 ;
338/22R; 338/221; 338/234 |
Current CPC
Class: |
H01C 1/014 20130101;
H01C 1/1406 20130101 |
Class at
Publication: |
338/232 ;
338/22.00R; 338/221; 338/234 |
International
Class: |
H01C 007/10; H01C
013/00; H01C 001/022 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2000 |
JP |
2000-146127 |
Claims
What is claimed is:
1. An electronic device comprising: an electronic device element
including first and second major surfaces opposing each other in
the thickness direction, and first and second electrodes disposed
on the first and second major surfaces, respectively; a conductive
first resilient contact member and a first positioning protrusion
which are not electrically connected to each other, the first
resilient contact member and the first positioning protrusion being
in contact with the first major surface at respective positions
thereof separated from each other; and a conductive second
resilient contact member and a second positioning protrusion which
are not electrically connected to each other, the second resilient
contact member and the second positioning protrusion being in
contact with the second major surface at respective positions
thereof separated from each other; wherein the first resilient
contact member and the second resilient contact member are in
resilient contact with the first and second electrodes,
respectively, so as to be electrically connected thereto; the first
resilient contact member opposes the second positioning protrusion
with the electronic device element therebetween, and is positioned
toward the periphery of the electronic device element from the
second positioning protrusion; and the second resilient contact
member opposes the first positioning protrusion with the electronic
device element therebetween, and is positioned toward an inner
portion of the electronic device element from the first positioning
protrusion.
2. An electronic device according to claim 1, further comprising a
case that contains the electronic device element, the first
resilient contact member, and the second resilient contact member,
wherein the first positioning protrusion and the second positioning
protrusion are provided in said case.
3. An electronic device according to claim 1, wherein the
electronic device element is a positive thermistor element.
4. An electronic device according to claim 3, wherein the positive
thermistor element has a substantially disc-shaped
configuration.
5. An electronic device according to claim 1, wherein the case is
made of a high heat-resistive resin.
6. An electronic device according to claim 1, wherein the first
resilient contact member includes one of a stainless steel plate
and a copper-titanium plate.
7. An electronic device according to claim 1, wherein the second
resilient contact member includes one of a stainless steel plate
and a copper-titanium plate.
8. An electronic device according to claim 1, wherein the case
includes a case body and a case cover which are hermetically
connected to each other.
9. An electronic device according to claim 8, wherein the case body
includes a plurality of ribs located at the periphery of an open
surface of the case body and the case cover is arranged to mate
with the plurality of ribs at the periphery of an open surface of
the case cover.
10. An electronic device according to claim 8, wherein the case
body includes first and second positioning protrusions extending
upwardly from the bottom of the case body so as to position the
electronic device element in the case.
11. An electronic device according to claim 10, wherein the
electronic device element is positioned by being clamped by the
first and second positioning protrusions and the first and second
resilient contact members 32.
12. An electronic device according to claim 11, wherein the
electronic device element is spaced from walls of the case.
13. An electronic device according to claim 8, wherein the first
and second positioning protrusions are integral with the case
body.
14. An electronic device according to claim 1, wherein the first
and second positioning protrusions are not electrically connected
to the first and second resilient contact members, and are not
electrically connected to the electrodes.
15. An electronic device according to claim 8, wherein the first
and second positioning protrusions are made of a material that is
different from that of the case body.
16. An electronic device according to claim 1, further comprising a
first terminal unit and a second terminal unit which are arranged
to clamp the electronic device element.
17. An electronic device according to claim 16, wherein the first
terminal unit includes the first resilient contact member, a first
socket for receiving a connecter pin and for electrical connection
to the connecter pin, and a first Connecting terminal.
18. An electronic device according to claim 17, wherein the
elements of the first terminal unit are integral with each
other.
19. An electronic device according to claim 16, wherein the second
terminal unit includes the second resilient contact member, a
second socket for receiving a connecter pin and for electrical
connection to the connecter pin, and a second Connecting
terminal.
20. An electronic device according to claim 19, wherein the
elements of the second terminal unit are integral with each other.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to electronic devices
including electronic device elements having electrodes provided on
opposite major surfaces of the respective electronic device
elements. In particular, the present invention relates to an
electronic device including an electronic device element supported
by being resiliently clamped by resilient contact members that are
arranged to individually contact the electrodes.
[0003] 2. Description of the Related Art
[0004] An electronic device related to the present invention is a
positive thermistor device. The positive thermistor device is used
for limiting electrical current in, for example, a motor driving
circuit of a refrigerator, a demagnetizing circuit for a picture
tube of a television or a monitor display, and other various
uses.
[0005] The positive thermistor device includes a positive
thermistor element including electrodes provided on respective
opposite major surfaces of the positive thermistor element. A
resilient contact member resiliently contacts each electrode,
whereby the resilient contact member presses the positive
thermistor element, thereby supporting the positive thermistor
element.
[0006] In the positive thermistor device, the positive thermistor
element deteriorates according to the condition and environment in
which it is used. As a result, the positive thermistor element is
abnormally heated, and is sometimes broken.
[0007] Electrical current sometimes continues to be applied to the
positive thermistor element via the resilient contact members even
when the positive thermistor element has been broken, whereby a
more serious accident may occur in which a case containing the
positive thermistor element is softened, and other defects may
occur.
[0008] In order to overcome these problems, a structure is
disclosed in, for example, Japanese Unexamined Patent Application
Publication No. 9-306704, in which when the positive thermistor
element is broken, fragments of the positive thermistor element are
moved by a spring action of the resilient contact members, thereby
opening a circuit and preventing the situation from becoming more
serious.
[0009] FIGS. 4A and 4B show the structure of the positive
thermistor device disclosed in the above Japanese Unexamined Patent
Application Publication No. 9-306704.
[0010] A positive thermistor element 1 shown in FIG. 4A is has an
overall disc-configured configuration. The positive thermistor
element 1 is provided with first and second electrodes (not shown)
disposed on first and second major surfaces 2 and 3 of the positive
thermistor element 1 and oppose each other in the thickness
direction thereof.
[0011] First and second terminal units 4 and 5 are arranged to
clamp the positive thermistor element 1. The first terminal unit 4
includes a first resilient contact member 6, and the second
terminal unit 5 includes a second resilient contact member 7.
[0012] First and second positioning protrusions 8 and 9 are
arranged to clamp the positive thermistor element 1.
[0013] The first resilient contact member 6 and the first
positioning protrusion 8 contact the first major surface 2 at
positions that are separate from each other on the first major
surface 2 of the positive thermistor element 1. The second
resilient contact member 7 and the second positioning protrusions 9
contact the second major surface 3 at positions that are separate
from each other on the second major surface 3. The first resilient
contact member 6 resiliently contacts the first electrode on the
first major surface 2 so as to be electrically connected to the
first electrode. The second resilient contact member 7 resiliently
contacts the second electrode on the second major surface 3 so as
to be electrically connected to the second electrode.
[0014] The first resilient contact member 6 opposes the second
positioning protrusion 9 with the positive thermistor element 1
therebetween, the first resilient contact member 6 being positioned
toward the periphery of the positive thermistor element 1 from the
second positioning protrusion 9. The second resilient contact
member 7 opposes the first positioning protrusion 8 with the
positive thermistor element 1 therebetween, the second resilient
contact member 7 being positioned toward the periphery of the
positive thermistor element 1 from the first positioning protrusion
8.
[0015] With this arrangement, when the positive thermistor element
1 is broken at a fracture point 10, as schematically shown in FIG.
4A, a fragment 11 moves so as to rotate in a direction along an
arrow 13 about a point, at which the fragment 11 is in contact with
the second positioning protrusion 9, as a fulcrum and a fragment 12
moves so as to rotate in a direction along an arrow 14 about a
point, at which the fragment 12 is in contact with the first
positioning protrusion 8, as a fulcrum, as shown in FIG. 4B, since
resilient pressing forces of the first and second resilient contact
members 6 and 7 are applied to the fragments 11 and 12,
respectively, which have been produced by the fracture.
[0016] The fragments 11 and 12 move in the directions along the
arrows 13 and 14, respectively, thereby interrupting electrical
current applied via the positive thermistor element 1 and opening a
circuit.
[0017] The directions along the arrows 13 and 14 of the movement of
the fragments 11 and 12, respectively, shown in FIG. 4B are
opposite to each other with respect to the fracture 10. That is,
the fragments 11 and 12 move so as to prevent each other from
moving in the directions along the arrows 13 and 14,
respectively.
[0018] Therefore, there is a problem in that even when an accident
occurs such that the positive thermistor element 1 is broken, the
fragments 11 and 12 sometimes do not sufficiently separate from
each other, whereby the circuit does not become open and the
electrical current continues to be applied through the broken
positive thermistor element 1.
[0019] The above-described problems occur not only in the positive
thermistor device. The problems may occur in any electronic device
in which an electronic component element corresponding to the
positive thermistor element is supported, is supplied with
electrical current, and is broken due to deterioration in the same
manner as the above-described positive thermistor device.
SUMMARY OF THE INVENTION
[0020] Preferred embodiments of the present invention provide an
electronic device in which the above-described problems are
overcome.
[0021] According to a preferred embodiment of the present
invention, an electronic device includes an electronic device
element including first and second major surfaces opposing each
other in the thickness direction, and first and second electrodes
disposed on the first and second major surfaces, respectively, a
conductive first resilient contact member and a first positioning
protrusion which is not electrically connected to the first
resilient contact member, the first resilient contact member and
the first positioning protrusion being in contact with the first
major surface at respective positions thereof separated from each
other, and a conductive second resilient contact member and a
second positioning protrusion which is not electrically connected
to the second resilient contact member, the second resilient
contact member and the second positioning protrusion being in
contact with the second major surface at respective positions
thereof that are separated from each other. The first resilient
contact member and the second resilient contact member are in
resilient contact with the first and second electrodes,
respectively, so as to be electrically connected thereto.
[0022] The first resilient contact member opposes the second
positioning protrusion with the electronic device element
therebetween, and is positioned toward the periphery of the
electronic device element from the second positioning protrusion.
The second resilient contact member opposes the first positioning
protrusion with the electronic device element therebetween, and is
positioned toward an inner portion of the electronic device element
from the first positioning protrusion.
[0023] The electronic device according to preferred embodiments of
the present invention preferably further includes a case for
receiving the electronic device element, the first resilient
contact member, and the second resilient contact member. The first
positioning protrusion and the second positioning protrusion may be
provided in the case.
[0024] The electronic device according to preferred embodiments of
the present invention may include a positive thermistor device
which includes a positive thermistor element as an electronic
device element.
[0025] According to preferred embodiments of the present invention,
the first and second resilient contact members and the first and
second positioning protrusions resiliently clamp the electronic
device element. Only the first and second resilient contact members
function as conductors for supplying electrical current. The first
resilient contact member opposes the second positioning protrusion
with the electronic device element therebetween, and is positioned
toward the periphery of the electronic device element from the
second positioning protrusion. The second resilient contact member
opposes the first positioning protrusion with the electronic device
element therebetween, and is positioned toward an inner portion of
the electronic device element from the first positioning
protrusion. Therefore, fragments produced by fracture of the
electronic device element move in the same direction as each other
with respect to the position of the fracture by being resiliently
pressed by pressing forces of the first and second resilient
contact members, whereby the fragments smoothly move, thereby
quickly and reliably interrupting electrical current applied via to
the electronic device element.
[0026] Therefore, a highly safe electronic device is provided.
[0027] When the case which is included in the electronic device
according to various preferred embodiments of the present invention
is made of a resin, and the electronic device element included
therein is broken, electrical current is quickly interrupted, and
abnormal heat generation is thereby avoided, whereby a risk of
entering into an accident mode such as softening of the case can be
reliably prevented.
[0028] Other elements, characteristics, features and advantages of
the present invention will become more apparent from the following
detailed description of preferred embodiments of the present
invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a sectional view of a critical portion of a
positive thermistor device 21 according to a preferred embodiment
of the present invention;
[0030] FIG. 2 is a perspective view of the positive thermistor
device 21 shown in FIG. 1, with a case cover 24 being separated
from other components;
[0031] FIGS. 3A and 3B are schematic diagrams of a positive
thermistor element 1 included in the positive thermistor device 21
shown in FIG. 1, which is broken and thereby interrupts electrical
current; and
[0032] FIGS. 4A and 4B are schematic diagrams of a positive
thermistor element included in a known positive thermistor device,
which is broken and thereby interrupts electrical current as in the
positive thermistor device 21 shown in FIGS. 3A and 3B.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] FIGS. 1 to 3A and 3B show a positive thermistor device 21
according to a preferred embodiment of the present invention.
[0034] FIG. 1 is a sectional view of a critical portion of the
positive thermistor device 21. FIG. 2 is a perspective view of the
positive thermistor device 21 of which a component is separated
from the other components. FIGS. 3A and 3B are schematic diagrams
of a positive thermistor element 1 included in the positive
thermistor device 21 shown in FIG. 1, which is broken and thereby
interrupts electrical current.
[0035] The positive thermistor device 21 is provided with a case
22. The case 22 preferably includes a case body 23 and a case cover
24.
[0036] The positive thermistor device 21 is provided with a
positive thermistor element 25 and first and second terminal units
26 and 27 received in the case 22.
[0037] The case body 23 and the case cover 24 are preferably made
of a high heat-resistive resin, such as phenol, polyphenylene
sulfide, or polybutylene terephthalate, of which the flame
retardance corresponds to 94V-0 according to the Underwriters'
Laboratories (UL) Standard. A part of the bottom of the case body
23 protrudes so that the case body 23 receives a positive
thermistor element 25. The case body 23 and the case cover 24
preferably have shapes so as to contain various components such as
the positive thermistor element 25 and the first and second
terminal units 26 and 27.
[0038] The positive thermistor element 25 having a Curie point of,
for example, about 130.degree. C. preferably has an overall
disc-shaped configuration, and is provided with first and second
electrodes 30 and 31 disposed on first and second major surfaces 28
and 29, respectively, of the positive thermistor element 25, which
oppose each other in the thickness direction. The positive
thermistor element 25 is inserted into the case body 23 at a center
thereof in a manner such that the electrodes 30 and 31 face toward
sides of the case body 23.
[0039] The first and second electrodes 30 and 31 are preferably
individually made of, for example, nickel as lower layers and
silver as upper layers. Each lower layer is preferably exposed at
the periphery of the upper layer so that migration of silver of the
upper layer is avoided.
[0040] The shape of the positive thermistor element 25 is not
limited to a disc, and the positive thermistor element 25 may be
formed to have, for example, a substantially rectangular
plate-shaped configuration or may have other shapes.
[0041] The first and second terminal units 26 and 27 are inserted
into the case body 23 so as to clamp the positive thermistor
element 25. The first and second terminal units 26 and 27 are
preferably made of metallic plates.
[0042] The first terminal unit 26 includes a first resilient
contact member 32, a first socket 33 for receiving a connecter pin
(not shown) and for electrical connection to the connecter pin, and
a first Connecting terminal 34.
[0043] According to the present: preferred embodiment, a plate
material for the first resilient contact member 32, and the plate
material for the first socket 33 and the first Connecting terminal
34 which are included in the first terminal unit 26 are
independently prepared, and are individually formed by welding,
caulking, or other suitable process. The first terminal unit 26 and
the components included therein may be arranged to be integral with
each other.
[0044] The first resilient contact member 32 preferably is made of
a plate, such as a stainless steel plate or a copper-titanium alloy
plate, which has a superior thermal stress relaxation
characteristic so that the resiliency can be maintained when the
positive thermistor element 25 generates heat, and is plated with
nickel as needed. The plate as a material for the first socket 33
and the first Connecting terminal 34 is preferably made of a
stainless steel, a copper-titanium alloy, a copper-nickel alloy, or
other suitable materials.
[0045] The second terminal unit 27 includes a second resilient
contact member 35, a second socket 36, a third socket 37, a second
Connecting terminal 38, and a third Connecting terminal 39. The
second terminal unit 27 is preferably made of the same material as
that used to form the first terminal unit 26 and by the same
manufacturing method as thereof.
[0046] The first terminal unit 26 is positioned by a wall portion
40 and other portions in the case body 23 so that the first
Connecting terminal 34 protrudes from the case body 23 so as to be
connected to an external circuit. The case cover 24 is provided
with a hole 41 through which the connecter pin is inserted into the
first socket 33.
[0047] The second terminal unit 27 is positioned by a wall portion
42 and other potions provided in the case body 23 so that the
second and third Connecting terminals 38 and 39 protrude from the
case body 23 so as to be connected to an external circuit. The case
cover 24 is provided with a hole 43 through which the connecter pin
is inserted into the second socket 36.
[0048] A hole through which the connecter pin is inserted into the
third socket 37 is not provided. The third socket 37 may be
omitted.
[0049] The holes 41 and 43 are preferably made as small as the
connecter pins can be inserted therethrough, whereby air-tightness
of the case 22 is improved, and the positive thermistor device 21
can be made more resistive to environmental changes.
[0050] The case body 23 and the case cover 24 are hermetically
connected to each other so that the air-tightness of the case 22 is
improved. The case body 23 is provided with two hooks 44, and the
case cover 24 is provided with mating parts 45 which receive the
respective hooks 44 and mate therewith. The case body 23 and the
case cover 24 are snap-coupled with each other, and are
hermetically connected to each other.
[0051] The case body 23 is provided with ribs 46 at the periphery
of an open surface of the case body 23. The case cover 24 is
arranged to tightly receive the ribs 46 at the periphery of an open
surface of the case cover 24, which is not shown.
[0052] The structure of the case 22 for positioning the positive
thermistor element 25 is described below.
[0053] In FIG. 1, the case body 23 is provided with first and
second positioning protrusions 47 and 48 rising from the bottom of
the case body 23. The positive thermistor element 25 is positioned
by being clamped by the first and second positioning protrusions 47
and 48 and the first and second resilient contact members 32 and
35, whereby the positive thermistor element 25 is maintained in the
case 22 by being separated from the walls thereof.
[0054] The first resilient contact member 32 and the first
positioning protrusion 47 are in contact with the first major
surface 28 of the positive thermistor element 25 at positions that
are separated from each other. The second resilient contact member
35 and the second positioning protrusion 48 are in contact with the
second major surface 29 of the positive thermistor element 25 in
positions thereon separated from each other. The first resilient
contact member 32 and the second resilient contact member 35 are
disposed, opposing each other, along a diagonal, and the first
positioning protrusion 47 and the second positioning protrusion 48
are disposed, opposing each other, along the other diagonal.
[0055] In this case, the first and second resilient contact members
32 and 35 are resiliently in contact with and electrically
connected to the first and second electrodes 30 and 31,
respectively, of the positive thermistor element 25. The first and
second positioning protrusions 47 and 48 are preferably integral
with the case body 23, and are electrically insulative, whereby the
first and second positioning protrusions 47 and 48 are not
electrically connected to the first and second resilient contact
members 32 and 35, and are not electrically connected to the
electrodes 30 and 31.
[0056] The first and second positioning protrusions 47 and 48 may
be made of a material that is different from that of the case body
23. The first and second positioning protrusions 47 and 48 may be
made of a metal as long as the first and second positioning
protrusions 47 and 48 are electrically separated from the first and
second resilient contact members 32 and 35.
[0057] The first resilient contact member 32 opposes the second
positioning protrusion 48 with the positive thermistor element 25
therebetween, and is positioned toward the periphery of the
positive thermistor element 25 from the second positioning
protrusion 48.
[0058] The second resilient contact member 35 opposes the first
positioning protrusion 47 with the positive thermistor element 25
therebetween, and is positioned toward an inner side of the
positive thermistor element 25 from the first positioning
protrusion 47.
[0059] In the positive thermistor device 21, when the positive
thermistor element 25 is broken by a spark or the like at a
fracture point 49, as schematically shown in FIG. 3A, a fragment 50
moves so as to rotate in a direction along an arrow 52 about a
point, at which the fragment 50 is in contact with the second
positioning protrusion 48, as a fulcrum and a fragment 51 moves so
as to rotate in a direction along an arrow 53 about a point, at
which the fragment 51 is in contact with the first positioning
protrusion 47, as a fulcrum, as shown in FIG. 3B, since resilient
pressing forces of the first and second resilient contact members
32 and 35 are applied to the fragments 50 and 51, respectively,
which have been produced by the fracture.
[0060] The movements of the fragments 50 and 51 in the directions
along the arrows 52 and 53, respectively, are toward the same side
of the positive thermistor element 25 as each other with respect to
the fracture 49. That is, the movement of each fragment 50 or 51 in
the direction along the arrow 52 or 53, respectively, contributes
to the movement of the other fragment 51 or 50. This is because the
first resilient contact member 32 is disposed toward the periphery
of the positive thermistor 25 from the second positioning
protrusion 48, and the second resilient contact member 35 is
disposed toward an inner side of the positive thermistor element 25
from the first positioning protrusion 47.
[0061] With this arrangement, the fragments 50 and 51 can smoothly
move without friction occurring between each other.
[0062] In FIG. 3B, when the fragments 50 and 51 are displaced, a
conductive path between the first and second resilient contact
members 32 and 35 via the positive thermistor element 25 is
interrupted, whereby a circuit becomes open. A risk of entering
into a more dangerous accident mode can be avoided, in that
abnormal heat-generation continues after the positive thermistor
element 25 has been broken.
[0063] The present invention is not limited to preferred
embodiments described above with reference to the drawings, and the
present invention may cover various modifications and equivalents
of the embodiment included within the sprit and scope of the
present invention.
[0064] For example, although according to preferred embodiments
shown in the drawings, the positive thermistor device 21 includes
the case :22, the case 22 may be omitted when the first and second
resilient contact members 32 and 35 are supported by a structure
other than the case 22, the first and second positioning
protrusions 47 and 48 are provided on a structure other than the
case 22, and the positive thermistor element 25 can be supported by
being clamped by the first and second resilient contact members 32
and 35 and the first and second positioning protrusions 47 and
48.
[0065] Although a positive thermistor device is used in the
above-described preferred embodiments, the present invention is not
limited to the positive thermistor device. The present invention
may be applied to other electronic devices in which electronic
device elements corresponding to the positive thermistor element
are supported and are supplied with electrical current in the same
manner as the above positive thermistor device, and are broken due
to deterioration.
[0066] While preferred embodiments of the invention have been
disclosed, various modes of carrying out the principles disclosed
herein are contemplated as being within the scope of the following
claims. Therefore, it is understood that the scope of the invention
is not to be limited except as otherwise set forth in the
claims.
* * * * *