Measuring and testing – Fluid pressure gauge – Electrical
Reexamination Certificate
2002-01-31
2003-09-16
Williams, Hezron (Department: 2855)
Measuring and testing
Fluid pressure gauge
Electrical
C073S754000, C073S727000
Reexamination Certificate
active
06619132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sensor used for measuring physical quantity etc., which is specifically used as a pressure sensor for converting fluid pressure into an electric signal to output to the outside.
2. Description of Related Art
Various sensors are used in measuring physical quantity etc. For instance, a pressure sensor which detects pressure and converts the pressure into an electric signal is used for measuring fluid pressure.
Such pressure sensor includes a joint clamped and fixed to a mount, a diaphragm attached to the joint by beam-welding etc., a pressure detecting element such as a strain gauge provided to the diaphragm, a circuit portion electrically connected to the pressure detecting element and a terminal for inputting and outputting the electric signal from the circuit portion, where the fluid pressure introduced to a pressure introducing port of the diaphragm is converted to strain of diaphragm, the strain being detected by the pressure detecting element. The diaphragm and the pressure detecting element are collectively referred to as a sensor module.
Conventional examples of pressure detecting sensor will be described below.
FIG. 16
shows a first conventional example of pressure sensor.
In
FIG. 16
, a sensor module
101
attached with a pressure detecting element
100
is provided to a joint
102
. A cap-shaped housing
103
is attached to the joint
102
and a circuit portion
104
is accommodated within a space formed between the housing
103
and the joint
102
.
In the first conventional example, the circuit portion
104
is composed of a printed circuit board
105
and electrical components
106
and terminal
107
respectively attached to the printed circuit board
105
The electrical components
106
are composed of IC chip and capacitor etc., which are installed on the printed circuit board
105
by soldering. The printed circuit board
105
and the pressure detecting element
100
of the sensor module
101
are electrically connected through the wiring
108
and the base
111
. The terminal
107
is composed of an intermediate terminal
109
and an I/O terminal
110
connected to the intermediate terminal
109
. An end of the intermediate terminal
109
is connected to the printed circuit board
105
by soldering etc.
FIG. 17
shows a second conventional example of pressure sensor.
In
FIG. 17
, the circuit portion
104
of the second conventional example is composed of a flexible circuit board
115
, and electrical components
106
and terminal
107
respectively attached to the flexible circuit board
115
.
The flexible circuit board
115
is electrically connected to the pressure detecting element
100
through the wiring
108
. The terminal
107
has an end electrically connected to the flexible circuit board
115
by soldering etc and another end exposed to a connecting port
103
A opening toward the outside of the housing
103
.
FIG. 18
shows a third conventional example of pressure sensor.
In
FIG. 18
, the circuit portion
104
of the third conventional example is composed of a ceramic board
125
provided inside a housing
103
, electrical components
106
and terminal
107
respectively attached to the ceramic circuit board
125
.
The ceramic circuit board
125
is electrically connected to a pressure detecting element
100
through a wiring
108
. The terminal
107
is composed of an intermediate terminal
109
and an I/O terminal
110
connected to the intermediate terminal
109
. An end of the intermediate terminal
109
is connected to the ceramic circuit board
125
by soldering etc.
FIG.
19
and
FIG. 20
show a fourth conventional example of pressure sensor.
In these figures, sensor module
101
of the fourth conventional example is attached to a joint
102
by beam welding etc. A substantially cylindrical housing
113
having partition thereinside is attached to the joint
102
.
In the housing
113
, a base
114
is attached to the joint
102
and a circuit board
135
is attached to the base
114
. Further, a terminal
118
is attached to the base
114
through a terminal base
117
.
FIG. 21
shows a fifth conventional example of pressure sensor. The fifth conventional example is disclosed in Japanese Patent Laid-Open Publication No. Hei11-237291.
In
FIG. 21
, a sensor module
201
of the fifth example is welded and fixed to a tapered butt weld portion
202
A of the joint
202
. A substantially cylindrical housing
203
is attached to a flange
202
B of the joint
202
through a crimping portion
202
C.
Inside the housing
203
, a circuit board
205
is attached to the joint
202
through a case
204
. Further, a terminal
207
is attached to the circuit board
205
through a terminal base
206
. The circuit board
205
and the pressure detecting element of the sensor module
201
is electrically connected through a base
208
.
In the fourth and the fifth conventional examples, the joint
102
and
202
are fixed by a screw to a mount, thereby also working as a flange as an attachment portion.
The sensor modules
101
and
201
are butted to the joints
102
and
202
to be welded.
The housings
113
and
203
are attached to the joints
102
and
202
through the crimping portions
102
A and
202
C.
In the pressure sensor of the above-described first conventional example, since the electrical components
106
, the base
111
and the I/O terminal
110
have to be connected on the printed circuit board
105
, so that the intermediate terminal
109
is required for escaping from the force applied to the I/O terminal
110
.
Accordingly, in the first conventional example, the number of the components is increased to enlarge the size of the entire sensor and increasing number of connection between mutual components is required, thereby increasing production cost. Further, since such large number of connections between components is required, much cost is necessary for securing reliability of the connection process. Further, much process such as soldering is required for electrically connecting the board and the terminal, thereby increasing production cost of the pressure sensor.
In the pressure sensor of the second conventional example, since the terminal
107
is soldered to the flexible circuit board
115
, production cost can be increased. Further, when the electrical components
106
and the terminal
107
are soldered to the flexible circuit board
115
, the flexible circuit board
115
has to be guarded with a glass epoxy plate in order to improve rigidity thereof, thereby also increasing production cost.
In the pressure sensor of the third conventional example, since two types of terminal, i.e. the I/O terminal
110
and the intermediate terminal
109
, are required as the terminal
107
, the number of components are increased to enlarge the size of the entire sensor and increasing the production cost. Further, since the ceramic of high unit component price is used as the circuit board, the production cost is increased therefore.
On the other hand, the joints
102
and
202
of the pressure sensors of the fourth and the fifth conventional examples also work as the flange. In other words, the joints
102
,
202
and the flange are integrally formed.
In the pressure sensor of the fourth conventional example, since the sensor module
101
is butted to the joint
102
to be welded, the bonding portion of the joint
102
is projected, thereby lengthening dimension of the entire pressure sensor.
On the other hand, in the pressure sensor of the fifth conventional example, since the sensor module
201
is welded and fixed in a manner that the sensor module
201
is buried to the tapered butt weld portion
202
A of the joint
202
, the problem of lengthening the dimension of the pressure sensor can be avoided. However, since the welding is conducted in an inclined direction or perpendicular direction, welding process such as alignment of weld line etc. is troublesome.
Further, in the pressure sensor of the fourth and fifth conventional examples, the circuit boards
135
Imai Atsushi
Tomomatsu Yoshihiro
Yamagishi Kouzou
Ellington Alandra N.
Flynn ,Thiel, Boutell & Tanis, P.C.
Nagano Keiki Co. Ltd.
Williams Hezron
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