Geometrical instruments – Distance measuring – Scale reading position sensor
Reexamination Certificate
1999-03-15
2001-06-19
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Distance measuring
Scale reading position sensor
C033S709000
Reexamination Certificate
active
06247242
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mechanism in which a linear sensor is provided to detect a position of a movable member of a device such as a car stereo and a liquid display panel, and more particularly to a mechanism which converts the movement of the movable member into a linear movement of a slider in the linear sensor.
The car stereo and liquid crystal monitor are each provided with a linear sensor to detect a moving distance of a movable portion so that the movable portion may be controlled dependent on the detected distance. A magnetoresistance linear sensor or a electric resistance linear sensor is used as the linear sensor.
Referring to
FIG. 8
showing a basic construction of a magnetoresistance linear sensor, the sensor has a flat and rectangular magnetic scale
30
, a detector
31
disposed opposite the magnetic scale
30
and arranged to be relatively moved with respect thereto, and a signal processing circuit
32
. The magnetic scale
30
comprises a base
33
and a magnetic medium
34
formed on the base
33
. A plurality of magnetic scale plates
35
are mounted on the magnetic medium
34
.
The detector
31
comprises a magnetoresistance element
36
and a holder
37
for supporting the magnetoresistance element
36
. The magnetoresistance element
36
opposes the magnetic scale plates
35
. When the detector
31
relatively moves along the scale plates
35
, an output voltage generated by the magnetoresistance element
36
is applied to the signal processing circuit
32
. The signal processing circuit
32
, having a preamplifier
32
A and a detecting circuit
32
B, calculates the quantity of relative displacement of the detector
31
.
FIG. 9
shows a basic construction of an electric resistance linear sensor. The linear sensor comprises a resistor
40
formed by printing substrate. The resistor
40
has a ground terminal
41
and a source terminal
42
at both the ends thereof. A movable contact
44
is adapted to contact and to slide across the resistor
40
, thereby generating a voltage which varies in accordance with the position of the movable contact
44
.
In order to detect a moving distance of a movable member with such a linear sensor, the sensor is further provided with a base member on which the magnetic scale
30
or the resistor
40
is mounted. The detector
31
or the movable contact
44
is mounted on a slider which is slides along the base member. The base member is attached to a fixed member of a device while the slider is attached to the movable member.
The linear sensor is disposed in a device in consideration to space efficiency therein. Hence, the slidable range, that is the stroke of the slider, or the moving direction thereof does not always coincide with the moving range or the direction of the movable member of the device. In addition, although the slider in the linear sensor is capable only of linear movement, some of the movable members such as a flap provided in a operational flap deck are angularly displaced. Hence the movable member is mounted on the slider of the linear sensor by way of a mechanism for converting the displacement of the movable member to a linear displacement within the slidable range of the slider.
FIGS. 5
to
7
show conventional mechanisms for detecting positions.
Referring to
FIG. 5
, a linear sensor
73
has a sensor base
73
A and a slider
73
B slidably mounted on the base
73
A. The base
73
A is mounted, by way of an attaching portion
73
C, on a fixed member
71
of the device in which the sensor
73
is provided. The slider
73
B is operatively connected to a movable member
72
of the device through an arm
50
. More particularly, the arm
50
has an elongated hole
50
B at a center thereof with which the slider
73
B is engaged. An elongated hole
50
A is formed at a base end of the arm
50
with which a pivot
51
projecting from the fixed member
71
is engaged, thereby pivotally mounting the arm
50
on the fixed member
71
. The other end of the arm
50
is pivotally mounted on the movable member
72
by a screw
52
. Thus, when the movable member
72
moves within a range R
1
, the slider
73
B slides on the base
73
A in a range R
2
, so that the linear displacement of the movable member
72
is detected as the linear displacement of the slider
73
B. The ratio R
1
:R
2
is determined in accordance with the position of the hole
50
B for connecting the arm
50
with the slider
73
B.
Referring to
FIG. 6
, a connecting plate
60
is attached to the movable member
72
. The connecting plate
60
has a slide groove
60
A inclined at a predetermined angle with respect to the moving direction of the movable member
72
. The slider
73
B is engaged with the groove
60
A. The linear displacement of the movable member
72
in the range R
1
is detected as the linear displacement of the slider
73
B in the range R
2
which extends in a direction perpendicular to the moving direction of the movable member
72
. The ratio R
1
:R
2
is determined in accordance with the angular position of the slide groove
60
A.
In a conventional mechanism shown in
FIG. 7
, a slide plate
61
is further slidably mounted on the connecting plate
60
. The slide plate
61
has a pair of parallel slide grooves
61
A, each engaging a shaft
62
securely mounted on the fixed member
71
and extending in a direction perpendicular to the slide plate
61
. The slider
73
B of the linear sensor
73
is attached to the slide plate
61
. Hence, the slide plate
61
slides in parallel to the sliding direction of the slider
73
B. The linear movement of the movable member
72
is converted to linear movement of the slide plate
61
in the direction perpendicular to the moving direction of the movable member
72
. The movement of the slider plate
61
causes the slider
73
B to move on the base
73
A.
However, there are problems in the above described conventional mechanisms. In the example shown in
FIG. 5
, the linear movement of the movable member
72
is converted to the angular displacement of the arm
50
, and the angular displacement is further converted to the sliding movement of the slider
73
B which is detected by the sensor. Thus the sliding distance of the slider
73
B does not become proportional to the moving distance of the movable member
72
, so that the sliding distance must be corrected by calculation. As a result, in the example of
FIG. 5
, the construction of the circuit becomes complicated.
Moreover, in the example of
FIG. 5
, the rotation of the arm
50
is transmitted to the slider
73
B through the elongated hole
50
B so that the slider
73
B is exerted with force in the rotational direction of the arm
50
.
In the example shown in
FIG. 7
, the slider
73
B is applied with force in a direction inclined with respect to the inclination of the slide groove
60
A. Hence in the examples of
FIGS. 5 and 7
, the slider
73
B cannot smoothly slide on the base
73
A. Furthermore, repeated operation causes mechanical damage to the linear sensor, so that the durability of the linear sensor is deteriorated.
In the examples shown in
FIGS. 5 and 6
, an extremely large space is required for the arm
50
to rotate or the connecting member
60
to slide so that the mechanism takes up a large space in the device. In particular, in the example of
FIG. 7
, in addition to the displacement of the connecting member
60
, the slide plate
61
must be further moved so that the mechanism occupies a large portion of the space in the device. Namely, all of the above described examples are inferior in space efficiency. This is a serious problem in a device such as a stereo and decks having various moving devices and controllers densely disposed within.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a mechanism for detecting the position of the movable member wherein the movement of the slider of the linear sensor is in proportion to the movement of the movable member, and which does not require a large space.
According to the present invention, there is provided a mechanism
Arent Fox Kintner & Plotkin & Kahn, PLLC
Fulton Christopher W.
Pioneer Electronic Corporation
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