Oscillator and communications device

Details Oscillator and communications device Oscillator and communications device

1999-05-20

2001-05-22

Grimm, Siegfried H. (Department: 2817)

Oscillators

With outer casing or housing

C331S096000, C361S752000

Reexamination Certificate

active

06236279

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oscillator and a communications device in which a circuit board and a resonator and the like are stored in a package.
2. Description of the Related Art
By way of background, an example of an oscillator will be discussed as shown in
FIGS. 6 and 7
, it being understood that this oscillator was not known at the time of the present invention and, therefore, is not prior art to the instant application.
FIG. 6
is an exploded perspective view of the oscillator, and
FIG. 7
is a cross-sectional view taken along the line Z—Z of FIG.
6
.
As shown in
FIGS. 6 and 7
, oscillator
110
comprises a package
111
, a case
130
, a resonator
120
and a circuit board
140
. The package
111
comprises a steel cap
112
and a stem
113
. Terminal pins
114
are provided at three corners of the stem
113
. The case
130
has a two-level concave portion
131
in its center, and is provided on top of the stem
113
. The resonator
120
comprises an electrode
122
, which is provided on two opposing faces of a dielectric substrate
121
, and a substantially circular electrode removal portion
123
is provided roughly in the center of the electrode
122
. Furthermore, the electrode
122
is also provided on the four side faces of the dielectric substrate
121
. The resonator
120
is held in the concave portion
131
of the case
130
, and the two-level structure of the concave portion
131
creates a space near an electrode removal portion
123
in the bottom face of the resonator
120
.
The circuit board
140
comprises a circuit pattern, such as a stripline, provided on an insulated substrate
141
. A FET
142
, a varactor diode
152
, a chip capacitor
143
and chip resistors
144
a
,
144
b
and
144
c
and the like are provided at predetermined positions on the substrate
141
. The circuit board
140
is mounted on the case
130
, and terminal electrodes
149
,
150
and
153
of the circuit board
140
are connected to the terminal pins
114
.
The case
130
, with the resonator
120
therein, is placed on the stem
113
and the circuit board
140
is mounted on the case
130
. Thereafter, a cap
112
is provided over the assembly. The cap
112
is hermetically sealed to the stem
113
, forming the oscillator
110
.
The characteristics of an oscillator are greatly affected by the relative positions of the resonator and the circuit board or the cap. That is, when the positions of the resonator and the cap change, the distribution of the electromagnetic field changes, greatly affecting the characteristics of the oscillator. This effect is particularly noticeable at high-frequency bands such as microwave and milliwave bands, which require positioning with precision of below 0.1 mm.
Therefore, in order to obtain the desired characteristics, it is necessary to repeatedly measure the characteristics of the oscillator while adjusting the relative position. Each time, the cap and the circuit board are removed and the position of the resonator is altered. Then, the circuit board is remounted and the cap is replaced.
However, some deviation in position of the cap inevitably occurs each time the cap is replaced. Consequently, when the cap is removed and the position of the resonator and the like is altered, the deviation in the position of the cap thereafter changes the distribution of the electromagnetic field, making it difficult to measure characteristics of the oscillator appropriately and with stability. Furthermore, due to the deviation in the position of the cap, the path of a ground electrode from the cap to the stem is also unstable, affecting the characteristics of the oscillator.
SUMMARY OF THE INVENTION
The oscillator of the present invention has been realized in consideration of the problems described above.
The oscillator of the present invention comprises a package, a resonator held in the package; a circuit board; and a member for securing the package, the member for securing contacting two opposing inside faces of the package.
Consequently, the cap of the package is secured, and the electromagnetic field distribution of the oscillator is stable.
Preferably, the member for securing comprises a metal plate, connected in one direction to a ground electrode of the circuit board.
Consequently, the path of ground current is stabilized.
Preferably, the member for securing, which contacts two opposing inside faces of the package, has an elastic member for securing which contacts one inside face, and a rigid member for securing which contacts the other inside face.
Consequently, the force applied to the cap by the member for securing is not excessive.
Preferably, the member for securing contacts inside faces of the package in two directions, which are roughly at a right angle to each other.
Consequently, the cap is secured with more stability.
Preferably, the member for securing comprises a single plate-like member.
Consequently, the member for securing needs only a small number of components, making it easier to form.
The member for securing, which contacts one of the inside faces of the package, preferably has a sawtooth shape.
Consequently, the member for securing contacts the inside face of the package at many points.
A communications device of the present invention comprises a circuit for transmitting, a circuit for receiving and an antenna, the circuit for transmitting and/or the circuit for receiving comprising the above oscillator.
As a result, a communications device with stable characteristics can be obtained.


REFERENCES:
patent: 4586006 (1986-04-01), Emmons
patent: 4627533 (1986-12-01), Pollard
patent: 4628283 (1986-12-01), Reynolds
patent: 5661441 (1997-08-01), Morino et al.
patent: 505963A2 (1992-09-01), None
patent: 678974A2 (1995-10-01), None

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