Microwave oven

Electric heating – Microwave heating – Enclosed cavity structure

Reexamination Certificate

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Details

C219S702000, C126S29900R, C454S333000

Reexamination Certificate

active

06335521

ABSTRACT:

CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accuring under 35 U.S.C. §119 from my application MICROWAVE OVEN filed with the Korean Industrial Property Office on Oct. 11, 2000 and there duly assigned Serial No. 59845/2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to microwave ovens, and more particularly, to a microwave oven having an improved grill cover.
2. Description of Related Art
Referring to
FIG. 6
which is an exploded perspective view of a conventional wall-mounted microwave oven, the conventional microwave oven is comprised of a main body
101
formed with a cooking compartment
103
, and an outer casing
105
surrounding the main body
101
, to define an outer appearance of the microwave oven.
A tray
107
upon which food rests is placed within the cooking compartment
103
. In front of the cooking compartment
103
is installed a door
109
opening and closing the cooking compartment
103
, through which a user can put in and pick out the food. Beside the door
109
is installed a control panel
111
formed with a plurality of buttons by which the user can control the microwave oven. In the rear of the control panel
111
is installed a magnetron
115
supplying electromagnetic waves into the cooking compartment
103
.
The outer casing
105
is comprised of an upper casing
117
, a lower casing
121
and a rear casing
119
. The upper casing
117
takes a shape of inverse ‘U,’ surrounding the upper part and both side parts of the main body
101
, the lower casing
121
is installed in the lower of the main body
101
and the rear casing
119
is installed in the rear of the main body
101
.
On the lower casing
121
are installed a pair of air inlet ports
127
and a pair of hood lamps
129
. Through the air inlet ports
127
, air flows into the lower casing
121
, according to operation of a blowing fan
125
installed to the rear casing
119
, and the hood lamps
129
is installed adjacent to the air inlet ports
127
, to illuminate below the microwave oven.
On the top face of the upper casing
117
is formed an exhaust port
123
through which the air drawn through the air inlet ports
127
is exhausted outside the main body
101
. Between the upper of the main body
101
and the upper casing
117
is formed a grill member
135
having a number of air passing holes
133
. On the top of the main body
101
is formed a holding bracket
131
holding the grill member
135
. In front of the grill member
135
is provided a grill cover casing
141
, taking a shape of rectangular box, having longitudinal openings in the front face and the rear face thereof. In the front opening of the grill cover casing
141
is installed a grill cover
143
. Between the grill member
135
and the grill cover
143
is provided a switch
161
opening and closing the grill cover
143
installed in the front opening of the grill cover casing
141
.
FIG. 7
is a partial, sectional view showing an assembly of the grill cover
143
and the switch
161
taken along line VII—VII of
FIG. 6
, and
FIG. 8
is a view showing an operation state of the grill cover of FIG.
6
. As shown therein, the grill cover casing
141
is comprised of an inclination part
142
downwardly inclined toward the inside of the front opening thereof, with a predetermined inclination degree. On the outer upper surface of the grill cover casing
141
is formed an indentation part
141
a
indented from the surface thereof to a predetermine depth. On the outer lower plate of the grill cover casing
141
is formed a protrusion part
141
b
protruded transversely relative to the lower plate thereof. The grill cover casing
141
is allowed to closely contact an upper portion of the main body
101
and a lower surface of the upper casing
117
by means of the indentation part
141
a
and the protrusion part
141
b
. On the grill cover
143
installed in the front opening of the grill cover casing
141
is formed a link supporter
147
protruded toward the grill member
135
transversely, relative to the grill cover
143
.
The link supporter
147
has an elongated guide hole
147
a
(see
FIG. 8
) formed in the lengthwise direction thereof. On opposite sides of the rear lower portion of the grill cover
143
is provided a hinge
149
coupled to the grill cover casing
141
, opening and closing the front opening of the grill cover casing
141
. In the middle of the grill cover casing
141
is formed a bracket
165
taking a shape of inverse ‘U.’ One side of the bracket
165
is opened and the other side thereof is coupled to the grill member
135
. The switch
161
opening and closing the grill cover has a step motor
163
having a rotational shaft to drive of opening and closing of the grill cover
143
, and a link shaft
167
coupled to the rotational shaft of the step motor
163
. The step motor
163
is coupled to an external side of the bracket
165
. On one end of the link shaft
167
is formed a motor shaft accommodating part
167
a
coupled to the rotational shaft of the step motor
163
. On the other end of the link shaft
167
is formed a connection pin
167
b
connected to the elongated guide hole
147
a
of the link supporter
147
.
The connection pin
167
b
is accommodated in the elongated guide hole
147
a
, so as to slidably elevate along the elongated guide hole
147
a
. When the grill cover
143
is closed, the connection pin
167
b
is placed in the upper side of the elongated guide hole
147
a
of the link supporter
147
.
Referring to
FIG. 8
again, in the case that the grill cover
143
is opened, if the step motor
163
is activated for a predetermined period of time according to a signal from a controller (not shown), so that, for example, the motor shaft is rotated counterclockwise in view of the motor
163
, the link shaft
167
coupled to the rotational shaft of the step motor
163
is rotated counterclockwise. If the link shaft
167
is rotated counterclockwise, the connection pin
167
b
of the link shaft
167
is slid downward along the elongated guide hole
147
a
. If the connection pin
167
b
is slid downward, the grill cover
143
is forward rotated, to thereby open the front opening of the grill cover casing
141
. After a predetermined period of time has passed, the controller (not shown) activates the step motor
143
to stop its operation. If the step motor
163
stops, the grill cover
143
remains in the maximally opened state. At this time, the step motor shaft connected to the link shaft
167
supports the weight of the grill cover
143
.
In the case that the opened grill cover
143
is closed, if the rotational shaft of the step motor
163
is rotated clockwise by a control signal from the controller (not shown), the link shaft
167
coupled to the rotational shaft of the step motor
163
is rotated clockwise. If the link shaft
167
is rotated clockwise, the connection pin
167
b
of the link shaft
167
is slid upward along the elongated guide hole
147
a
of the link supporter
147
. If the connection pin
167
b
is slid upward, the grill cover
143
is rotated backward, to thereby close the front opening of the grill cover casing
141
. After a predetermined period of time has passed, the controller (not shown) activates the step motor
163
to stop its operation. If the step motor
163
stops, the grill cover
143
is closed. That is, the step motor
163
draws the grill cover
143
connected to the link shaft
167
by the rotation of the rotational shaft of the step motor
163
.
In the conventional microwave oven, while the operation to open the grill cover is being conducted, the weight of the grill cover is to be supported by the rotational shaft of the motor, thereby generating an excessive burden to the rotational shaft. Further, while the operation to close the grill cover is being conducted, the grill cover is to be drawn by the rotation force of the motor, thereby generating an over-load to the motor.
To open and close the grill cover, the motor has to b

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