Information
-
Patent Grant
-
6531671
-
Patent Number
6,531,671
-
Date Filed
Tuesday, March 13, 200123 years ago
-
Date Issued
Tuesday, March 11, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
A membrane circuit board switch used in a keyboard for generating key-pressing signals. The membrane circuit board switch has an upper membrane circuit layer, a lower membrane circuit layer, and a plurality of switch units. Each switch unit has a predetermined space between the upper and lower membrane circuit layers. The membrane circuit board switch particularly has a pressure regulating reservoir communicating with the predetermined spaces. When atmospheric pressure changes, the pressure regulating reservoir will adjust the pressure inside the predetermined spaces to make the predetermined distance keeping substantially constant.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a membrane circuit board switch, and more particularly, to a membrane circuit board switch with a pressure regulating reservoir.
2. Description of the Prior Art
Please refer to FIG.
1
and FIG.
2
.
FIG. 1
is a schematic diagram of a prior art membrane circuit board switch
10
used in a keyboard
12
.
FIG. 2
is a schematic diagram of a switch unit
32
of the membrane circuit board switch
10
shown in FIG.
1
. The membrane circuit board switch
10
is used in the keyboard
12
for generating key-pressing signals. The keyboard
12
comprises a base plate
14
, and a plurality of key mechanisms
16
. The membrane circuit board switch
10
is installed between the base plate
14
and the plurality of key mechanisms
16
. The membrane circuit board switch
10
comprises an upper membrane circuit
18
, a lower membrane circuit
22
, and a plurality of switch units
32
. The upper membrane circuit
18
comprises a plurality of upper contacts
20
. The lower membrane circuit
22
comprises a plurality of lower contacts
24
that correspond to the upper contacts
20
. Each upper contact
20
and its corresponding lower contact
24
form a switch unit
32
.
As shown in
FIG. 2
, the key mechanism
16
is up-and-down movably installed above the switch unit
32
for pressing the upper contact
20
to contact the lower contact
24
to generate a corresponding key-pressing signal. The lower membrane circuit
22
is positioned under the upper membrane circuit
18
. There is an interval material layered between the upper and lower membrane circuit layers for forming a predetermined space
28
with a predetermined distance
30
between the upper and lower contacts
20
,
24
. When the key mechanism
16
is depressed, the upper contact
20
is pressed down to contact the lower contact
24
. When the key mechanism
16
is released, or not depressed, the upper contact
20
will revert, or maintain the predetermined distance
30
from the corresponding lower contact
24
.
Please refer to FIG.
3
and FIG.
4
.
FIG. 3
depicts a state of the switch unit
32
shown in
FIG. 1
with lower atmospheric pressure.
FIG. 4
depicts a state of the switch unit
32
shown in
FIG. 1
with higher atmospheric pressure. Generally, there are 2 design choices of the said predetermined space
28
: interacting with the atmosphere or not. To keep unwanted particles (dust, steam etc.) out of the predetermined space
28
, the latter is usually chosen. However, when atmospheric pressure changes, the hermetic design of the predetermined space
28
can lead to malfunctioning of the switch unit
32
. As show in
FIG. 3
, when the atmospheric pressure drops (this may occur due to a change of height or temperature), the pressure inside the predetermined space
28
is higher than the atmospheric pressure. Therefore, it is not easy to make the upper contact
20
to contact the lower contact
24
. Furthermore, as shown in
FIG. 4
, when the atmospheric pressure rises, the pressure inside the predetermined space
28
becomes lower than the atmospheric pressure. Therefore, the upper contact
20
may not maintain the predetermined distance from the lower contact
24
, and thus makes unexpected contact with the lower contact
24
.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a membrane circuit board switch with a pressure regulating reservoir to solve the mention problems.
The present invention, briefly summarized, discloses a membrane circuit board switch used in a keyboard. The keyboard comprises a base plate, and at least one key mechanism. The membrane circuit board switch is installed between the base plate and the key mechanism. The membrane circuit board switch comprises an upper membrane circuit layer, a lower membrane circuit layer, and at least one pressure regulating reservoir communicates with the membrane circuit board switch. The upper membrane circuit layer comprises at least one upper contact. The lower membrane circuit layer comprises a corresponding lower contact. A predetermined space is formed with a predetermined distance between the upper and lower contacts by an interval material. The key mechanism can press the upper contact to contact the lower contact to generate a corresponding key-pressing signal. The pressure regulating reservoir communicates with the predetermined space to adjust the pressure inside the predetermined space. When the atmospheric pressure changes, the volume of the pressure regulating reservoir will adjust the pressure inside the predetermined space to make the predetermined distance keeping substantially constant.
It is an advantage of the present invention that the membrane circuit board switch prevents particles from entering the predetermined space, and it also adjusts the pressure inside the predetermined space to adapt to the changes of atmospheric pressure.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic diagram of a prior art membrane circuit board switch used in a computer keyboard.
FIG. 2
is a schematic diagram of a switch unit of the membrane circuit board switch shown in FIG.
1
.
FIG. 3
depicts a state of the switch unit shown in
FIG. 1
under a lower atmospheric pressure.
FIG. 4
depicts a state of the switch unit shown in
FIG. 1
under a higher atmospheric pressure.
FIG. 5
is a schematic diagram of a membrane circuit board switch used in a keyboard according to the present invention.
FIG. 6
is an exploded view of the membrane circuit board switch shown in FIG.
5
.
FIG. 7
is a schematic diagram of the switch unit shown in FIG.
5
.
FIG. 8
depicts a pressure regulating reservoir communicating with a predetermined space shown in FIG.
5
.
FIG. 9
depicts a state of the pressure regulating reservoir shown in
FIG. 5
under lower atmospheric pressure.
FIG. 10
depicts a state of the pressure regulating reservoir shown in
FIG. 5
under higher atmospheric pressure.
FIG. 11
is an exploded view of another embodiment of a membrane circuit board switch according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Please refer to FIG.
5
and FIG.
6
.
FIG. 5
is a schematic diagram of a membrane circuit board switch
50
used in a keyboard
52
according to the present invention.
FIG. 6
is an exploded view of the membrane circuit board switch
50
shown in FIG.
5
. The membrane circuit board switch
50
is used in the keyboard
52
for generating key-pressing signals. The keyboard
52
comprises a base plate
54
, and a plurality of key mechanisms
56
. The membrane circuit board switch
50
is installed between the base plate
54
and the plurality of key mechanisms
56
. The membrane circuit board switch
50
comprises an upper membrane circuit layer
58
, a lower membrane circuit layer
62
, and at least one pressure regulating reservoir
66
communicated with the membrane circuit board switch
50
.
Please refer to FIG.
6
and
FIG. 6
a
. The upper membrane circuit layer
58
comprises a plurality of upper contacts
60
. The lower membrane circuit layer
62
comprises a plurality of lower contacts
64
that correspond to the upper contacts
60
. The membrane circuit board switch
50
further comprises a printed layer
74
around the upper and lower contacts
60
,
64
and between the upper and lower membrane circuit layers
58
,
62
. The lower membrane circuit layer
62
is positioned under the upper membrane circuit layer
58
. The upper and lower membrane circuit layer
58
,
62
are glued to each other. Each upper contact
60
and its corresponding lower contact
64
form a switch unit
72
.
Please refer to FIG.
7
.
FIG. 7
is a schematic diagram of the switch unit
72
shown in FIG.
5
. The switch unit
72
is formed from corresponding upper and lower contacts
60
,
64
. The key mechanism
56
is up-and-down movably installed above the switch unit
72
for pressing the upper contact
60
to contact the lower contact
64
to generate a corresponding key-pressing signal. Because of the printed layer
74
between the upper and lower membrane circuit layers
58
,
62
, a predetermined space
68
is formed with a predetermined distance
70
between the upper and lower contacts
60
,
64
. When the key mechanism
56
is depressed, the upper contact
60
will be pressed downward to contact the lower contact
64
. When the key mechanism
56
is released, or not depressed, the upper contact
60
will revert, or maintain the predetermined distance
70
from the corresponding lower contact
64
.
Please refer to FIG.
8
.
FIG. 8
depicts the pressure regulating reservoir
66
communicating with the predetermined space
68
shown in FIG.
5
. The membrane circuit board switch
50
further comprises a plurality of air conduits
76
between the upper and lower membrane circuit layers
58
,
62
. The air conduits
76
connect the predetermined spaces
68
with each other and the pressure regulating reservoir
66
so that each predetermined space
68
communicates with the pressure regulating reservoir
66
. The pressure regulating reservoir
66
, the predetermined spaces
68
, and the air conduits
76
are communicated with each other and formed a close space that insulated from the atmosphere. The volume of the pressure regulating reservoir
66
is larger than the sum of the volumes of the predetermined spaces
68
and the air conduits
76
. The pressure regulating reservoir
66
can be a plastic bag, a soft rubber bag, or an extensible bag, as long as the volume of the pressure regulating reservoir is easier changed than the predetermined spaces.
Please refer to FIG.
9
and FIG.
10
.
FIG. 9
depicts a state of the pressure regulating reservoir
66
shown in
FIG. 5
under lower atmospheric pressure.
FIG. 10
depicts a state of the pressure regulating reservoir
66
shown in
FIG. 5
under higher atmospheric pressure. When the atmospheric pressure changes, the volume of the pressure regulating reservoir
66
will change with the atmospheric pressure to adjust the pressure inside the predetermined space
68
. Consequently, the upper contact
60
maintains the predetermined distance
70
from the lower contact
64
. The key mechanism
56
can thus press the upper contact
60
and cause the upper contact
60
to contact with the lower contact
64
.
As shown in
FIG. 9
, the predetermined space
68
communicates with the pressure regulating reservoir
66
through the air conduits
76
. When the atmospheric pressure drops, the volume of the pressure regulating reservoir
66
will increase, thus decreasing the pressure inside the predetermined space
68
until the pressure inside the predetermined space
68
is equal, or nearly so, to the atmospheric pressure. After adjusting for the pressure inside the predetermined space
68
, the key mechanism
56
can easily press the upper contact
60
to contact with the lower contact
64
.
As shown in
FIG. 10
, when the atmospheric pressure rises, the volume of the pressure regulating reservoir
66
will decrease, thus increasing the pressure inside the predetermined space
68
until the pressure inside the predetermined space
68
is equal, or nearly so, to the atmospheric pressure. After adjusting for the pressure inside the predetermined space
68
, the upper contact
60
maintains the predetermined distance
70
from the lower contact
64
, and the said malfunctioning problem will not occur.
Please refer to FIG.
11
.
FIG. 11
is an exploded view of the second embodiment of the present invention, a membrane circuit board switch
80
. The main difference between the membrane circuit board switches
50
,
80
is the manner of forming the predetermined space
68
. The predetermined space
68
of the membrane circuit board switch
50
is formed by the printed layer
74
. The predetermined space
68
of the membrane circuit board switch
80
, however, is formed by a middle layer
82
. The middle layer
82
is installed between the upper and lower membrane circuit layers
58
,
62
, and comprises a plurality of holes
84
that correspond to the upper and lower contacts
60
,
64
for forming the predetermined space
68
. The air conduits
76
can be formed between the upper membrane circuit layer
58
and the middle layer
82
, or between the lower membrane circuit layer
62
and the middle layer
82
by the printed layer.
In contrast to the prior art, the present invention has the pressure regulating reservoir
66
and the air conduits
76
that connect the predetermined spaces
68
with the pressure regulating reservoir
66
. When the atmospheric pressure changes, the pressure regulating reservoir
66
will adjust the pressure inside the predetermined spaces
68
so that the key mechanisms
56
can easily press the upper contact
60
to contact with the lower contact
64
. The pressure regulating reservoir
66
also ensures that the upper contact
60
maintains the predetermined distance
70
from the lower contact
64
. Furthermore, because the pressure regulating reservoir
66
, the predetermined spaces
68
, and the air conduits
76
according to the present invention are communicated with each other and formed a close space that insulated from the atmosphere, the present invention also prevents unwanted particles from entering into the predetermined space
68
.
Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
- 1. A membrane circuit board switch comprising:an upper membrane circuit layer having an upper contact; a lower membrane circuit layer positioned under the upper membrane circuit layer, the lower membrane circuit layer having a lower contact corresponding to the upper contact, and a predetermined space formed between the upper membrane circuit layer and the lower membrane circuit layer; and a pressure regulating reservoir communicated with the predetermined space through an air conduit; wherein the predetermined space, the air conduit, and the pressure regulating reservoir are insulated from the atmosphere; wherein the volume of the pressure regulating reservoir is easier changed than the predetermined space, so the pressure regulating reservoir adjusts the pressure inside the predetermined space when the atmospheric pressure changes.
- 2. The membrane circuit board switch of claim 1 wherein the pressure regulating reservoir is a plastic bag.
- 3. The membrane circuit board switch of claim 1 wherein the pressure regulating reservoir is a soft rubber bag.
- 4. The membrane circuit board switch of claim 1 wherein the pressure regulating reservoir is an extensible bag.
- 5. The membrane circuit board switch of claim 1 wherein the volume of the pressure regulating reservoir is larger than the sum of the volumes of the predetermined space and the air conduit.
- 6. The membrane circuit board switch of claim 1 further comprising a printed layer installed between the upper and lower membrane circuit layers and around the upper and lower contacts so as to form the predetermined space.
- 7. The membrane circuit board switch of claim 1 further comprising a middle layer installed between the upper and lower membrane circuit layers, the middle layer comprising a hole that corresponds to the upper and lower contacts for forming the predetermined space.
- 8. The membrane circuit board switch of claim 1 wherein the upper and lower membrane circuit layers are glued to each other.
Priority Claims (1)
Number |
Date |
Country |
Kind |
89106045 A |
Mar 2000 |
TW |
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4018999 |
Robinson et al. |
Apr 1977 |
A |
4345119 |
Latasiewicz |
Aug 1982 |
A |
4931601 |
Lavender |
Jun 1990 |
A |