Geometrical instruments – Indicator of direction of force traversing natural media – Level or plumb – terrestrial gravitation responsive
Reexamination Certificate
2002-03-21
2004-12-07
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Indicator of direction of force traversing natural media
Level or plumb, terrestrial gravitation responsive
C033S391000
Reexamination Certificate
active
06826844
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to sensor units, and more particularly to a sensor unit composed of a permanent magnet, a spherical body formed of a magnetic material, and a magnetic sensor and used for inclination and acceleration measurement.
The sensor units are employed in automobiles, game controllers, and projectors. The sensor units are preferably small in size and easy to incorporate into apparatuses.
2. Description of the Related Art
FIG. 1
is a diagram showing a sensor unit
10
disclosed in Japanese Laid-Open Patent Application No. 2000-180160. The sensor unit
10
includes a spherical body
13
formed of a magnetic material and supported on a spherically concave partition wall
12
in the center of a container
11
. The sensor unit
10
also has a permanent magnet
15
fixed to a bottom plate
14
of the container
11
and a Hall element
17
fixed to the bottom surface of a top plate
16
of the container
11
. The permanent magnet
15
generates a first magnetic field indicated by lines of magnetic force
18
. The magnetic spherical body
13
is magnetized by the first magnetic field so as to generate a second magnetic field indicated by lines of magnetic force
19
. The second magnetic field affects the Hall element
17
so that the Hall element
17
outputs voltage.
The sensor unit
10
has a height ho indicated by an arrow in FIG.
1
. In the sensor unit
10
, in the direction of the height thereof, the magnetic spherical body
13
is positioned in the center, the permanent magnet
15
is positioned below the magnetic spherical body
13
, and the Hall element
17
is positioned above the magnetic spherical body
13
.
The sensor unit
10
, for instance, is mounted in an electronic apparatus such as a vehicle or a projector. When the apparatus is inclined, the magnetic spherical body
13
rolls on the partition wall
12
so as to change position with respect to the permanent magnet
15
and the Hall element
17
. Thereby, a change is effected in the second magnetic field affecting the Hall element
17
so as to vary the output voltage thereof. The angle and direction of inclination of the electronic apparatus is detected based on the variation in the output voltage of the Hall element
17
.
In the above-described sensor unit
10
, especially, the Hall element
17
is provided above the magnetic spherical body
13
. Therefore, a part above the magnetic spherical body
13
takes up much space so that the height ho of the sensor unit
10
is required to be large, thereby making it difficult to downsize the sensor unit
10
.
Further, in a normal sensor unit, a Hall element is mounted on a printed board, being electrically connected with pads on the printed board. However, in the sensor unit
10
, the Hall element
17
is provided in an upper part of the sensor unit
10
, thus complicating a route of extension of interconnection lines from the Hall element
17
.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a sensor unit in which the above-described disadvantage is eliminated.
A more specific object of the present invention is to provide a sensor unit reduced in size and assembled with ease.
Another more specific object of the present invention is to provide a sensor unit performing detection with increased accuracy.
The above objects of the present invention are achieved by a sensor unit including a support body having a concave surface, a spherical body formed of a magnetic material and placed on the concave surface of the support body so as to roll freely thereon, a permanent magnet producing a magnetic field affecting the magnetic spherical body, and a magnetic sensor detecting a change in the magnetic field caused by the movement of the magnetic spherical body, wherein the magnetic spherical body and the permanent magnet are provided to oppose each other with a given distance therebetween in a vertical direction, the magnetic sensor is provided between the magnetic spherical body and the permanent magnet, and an output is produced in accordance with the detection by the magnetic sensor.
According to the above-described sensor unit, the magnetic sensor is provided by using a space between the magnetic spherical body and the permanent magnet provided to oppose each other with the given distance therebetween. Therefore, no additional space is required for providing the magnetic sensor. Accordingly, the sensor unit is downsized with a reduced height.
The above objects of the present invention are also achieved by a sensor unit including a support body having a concave surface, a spherical body formed of a magnetic material and placed on the concave surface of the support body so as to roll freely thereon, a permanent magnet producing a magnetic field affecting the magnetic spherical body, a magnetic sensor detecting a change in the magnetic field caused by the movement of the magnetic spherical body, and a printed board having first and second opposing surfaces, wherein the magnetic sensor is provided to the first surface of the printed board, the support body is fixed to the first surface of the printed board, the permanent magnet is fixed to the second surface of the printed board, and an output is produced in accordance with the detection by the magnetic sensor.
According to the above-described sensor unit, the magnetic sensor is provided by using a space between the magnetic spherical body and the permanent magnet provided to oppose each other with a given distance therebetween. Therefore, no additional space is required for providing the magnetic sensor. Accordingly, the sensor unit is downsized with a reduced height.
Additionally, the above-described sensor unit may include a Hall element for temperature compensation, the Hall element being provided to a surface of the permanent magnet on a side opposite to the printed board.
Thereby, temperature compensation is provided to the magnetic sensor and the permanent magnet, thus increasing detection accuracy.
The above objects of the present invention are also achieved by a sensor unit including a case, a printed board having a magnetic sensor provided thereto, a hanging member including a permanent magnet producing a magnetic field, and a hanging and support mechanism that hangs and supports the hanging member in the case so that the hanging member is allowed to swing while being restricted in displacement in a vertical direction, wherein the magnetic sensor detects a change in the magnetic field caused by a movement of the permanent magnet due to the displacement of the hanging member so that an output is produced in accordance with the detection by the magnetic sensor.
According to the above-described sensor unit, the hanging and support mechanism restricts displacement of the hanging member in the vertical direction so that no change is caused in the output even when vibration or impact is exerted on the sensor unit in the vertical direction. Therefore, the sensor unit has good impact resistance, thus assuring good detection accuracy.
The above objects of the present invention are also achieved by a sensor unit including a case, a printed board having a magnetic sensor provided thereto, a balancing assembly having a permanent magnet producing a magnetic field, and a pivot support mechanism that supports the balancing assembly in the case so that the balancing assembly is allowed to swing, wherein the magnetic sensor detects a change in the magnetic field caused by a movement of the permanent magnet due to the displacement of the balancing assembly with respect to the printed board so that an output is produced in accordance with the detection by the magnetic sensor.
The above-described sensor unit is reduced in size and easy to assemble.
Additionally, the above-described sensor unit may include a detection switch provided in the case so as to oppose the top part of the balancing assembly, and the detection switch may detect an upward displacement of the balancing assembly to make the output of the
Akieda Shinichiro
Arita Takashi
Endo Michiko
Funakoshi Katsuya
Kato Masayuki
Bennett G. Bradley
Nagano Fujitsu Component Limited
Staas & Halsey , LLP
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