Note: Descriptions are shown in the official language in which they were submitted.
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TIT~E: STRUCTURE OF CURSOR CONTROL DEVlCE
BACKGROUND OF THE INVENTION
(a) Field of the Invention:
The present invention relates generally to a cursor
control device construction, and more particularly to a
cursor control device construction which facilitates
mounting of the wheels, light sources and sensors on a
circuit board-and which permits a spindle of the wheel
to be disposed at a rela~ively higher position to
achieve --precise reading:of signals and-to~--enable- the
wheel to be mounted on the circuit board prior to tin
soldering.
(b) Descri~tion of the Prior Art:
Conventional cursor control devices may be
generally classified into three màin types, namely,
mechanical, optical and.semi-optical.
In semi-optical cursor control devices, the construction
generally includes a body containing a circuit board~
therein and having a hole in a bottom side thereof for
mounting of a ball which may roll freely therein. The
body also accommodates a couple of encoders, each
. including a wheel which has a spindle~extending~in~ the
direction of the ball, the spindle being provided with a
roller which is in a frictional relationship with the
ball, such that the wheel may rotate synchronously
therewith. The wheel is provided with a light source
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and a sensor on both sides. The light emitted by the
light source is just perpendicular to the spindle, and
the sensor is disposed in the proximity of the periphery
of the wheel so as to receive light passing via the
periphery of the wheel. When the wheel rotates, some of
the light emitted by the light source will be blocked by
the wheel while some will pass via the periphery thereof
to reach the sensor. These two conditions may be
respectively represented by 0 and 1. When the wheel
performs continuous rotation (whether clockwisely or
counter-clockwiselyl~ the following four signals will
be obtained: (1, 1), (0, 1), (0, 0) and (1, 0). After
undergoing conversion by means of the circuit board,
these signals may control a cursor to move across the
screen of a display. The two encoders are provided to
respectively control the cursor to move across the
screen horizontally and vertically, or in any other
direction.
However, since the roller at one end of the spindle
of the wheel rubs against the ball so that the ball and
the wheel may synchronously rotate, the spindle has to
be maintained at a certain height in order that the
roller may always be in contact with the ball withln a
suitable extent. In other words, the wheel may have a
lower rim thereof in contact with the circuit board
below when mounted thereon. Therefore, the wheel cannot
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be mounted on the circuit board before the circuit board
has undergone tin soldering since the wheel, due to its
material and its position on the circuit board, may be
easily damaged during the process. Besides, as the
spindle of the wheel has to be maintained at a certain
height, the diameter of the wheel is restricted and
cannot be increased as desired. If the diameter of the
wheel is prolonged, the wheel will certainly have the
lower rim thereof touching the body. However as reading
of signals may become more precise with the increase of
the diameter of the wheel, it is imperative to find a
solution to solve the above-mentioned problem.
Furthermore, the relative relationship among the
wheels, light sources, and sensors will greatly affect
the precision of signal reading. If these components
are not properly mounted and positioned on the body of
the cursor control device, signal reading will be
defective or will even fail. But in the prior art,
these components are individually welded to the circuit
board directly so that it is necessary to adjust their
position to ensure that they are properly positioned on
the circuit board, which is very inconvenient and time-
consumptive.
SUMMARY OF THE INVENTION
Accordingly, a primary object of the present
invention is to provide a cursor control device
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construction wherein a wheel has a larger diameter and a
spindle of the wheel may be arranged at a relatively
higher position to permit precise reading of signals and
to enable the wheel to be disposed above a circuit board
and to be mounted on the circuit board before the
circuit board is subjected to tin welding.
Another object of the present invention is to
provide a cursor control device construction wherein the
wheels, light sources and sensors may be conveniently
and speedily mounted and positioned on the circuit board
without the need for adjustment as in the prior art.
To achieve the above-mentioned objects, the cursor
control device construction according to the invention
essentially comprises a pair of encoders, each of which
consists of a securing seat with a plurality of
mountings for supporting a wheel and a couple
positioning slots for securing a light source and a
sensor, so that the wheel, light source and sensor may
be mounted on the securing seat before the securing seat
is mounted onto a circuit board by means of insert means
which are inserted into corresponding holes in the
circuit board. The securing seat further supports an
idle wheel which is located intermediate a roller at one
end of a spindle of the wheel and the ball for
transmitting rolling actions of the ball to the roller
so that the wheel may synchronously rotate with the
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ball. The provision of the idle wheel enables the
spindle of the wheel to be located at a relatively
higher position so that the diameter of the wheel may be
increased to achieve precise reading of signals and the
wheel may be mounted on the circuit board prior to tin
welding.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and advantages of
the present invention will be more clearly understood
from the following detailed description and the
accompanying drawings, in which,
Fig. l is a perspective view of the cursor control
device construction according to the present invention
in an assembled state;
Fig.lA is an enlarged view of part A of Figure 1;
Fig. 2 is a perspective exploded view of the present
invention;
Fig. 2A is an enlarged view of part A of Figure 2;
Fig. 2B is an enlarged view of part B of Figure 2;
Fig. 3 is a top view of the encoders and a ball of the
cursor control device construction according to the
present invention, and
Fig. 4 is a side view of the encoders and the ball of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to Figs. l and 2, the cursor control
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device construction according to the present invention
essentially comprises a body lO, a cap 11 having a
plurality of push buttons 12 for sealing the interior of
the body 10, and a circuit board 13 accommodated within
the body 10. The body 10 further has a circular hole 14
formed in a bottom side thereof for accommodating a ball
15, which may roll freely within the hole 14.
The body 10 is provided with a pair of encoders 16.
Each encoder 16 includes a wheel 17 having a spindle 18
extending in the direction of the ball 15, the spindle
18 having one end thereof fixedly provided with a roller
19. A securing seat 20 is disposed below the wheel 17
and has a plurality of plate-like mountings 24, 25, 26
respectively having slots 21, 22 and 23 for pivotally
supporting the spindle 18, such that the wheel 17 may be
disposed beside an inner side of the mounting 24 and the
roller 19 may be.~disposed intermediate the mountings Z5
- - and 26. ~he mountings 25 and 26 are~ fur.ther
.. .. = ~= . . . ~
respectively provided with individual notches 27, 28 in
a vertical side thereof at a same elevation. An idle
wheel 29 is disposed at a position lower than the
spindle 19, with a spindle 30 at both ends thereof
pivotally supported by the notches 27, 28. The idle
wheel 29 is located between the roller 19 and the ball
15 and is in contact with both the roller 19 and the
ball 15, so that the idle wheel 29 may transmit the
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rolling action of the ball 15 to the roller 19 (see
Figs. 3 and 4).
A light source 31 (such as an LED) and a sensor 32
are individually disposed on both sides of the wheel 17.
The light source 31 and the sensor 32 are respectively
inserted into positioning slots 33 and 34 of the
securing seat 20. Two through holes 35 are formed in
one side of the positioning slot 34 to allow light
emitted from the light source 31 to reach the sensor 32
via the wheel 17. The positioning slots 33 and 34 have
individual positioning plates 36 and 37 at an upper end
thereof for positioning the light source 31 and the
sensor 32 respectively. ~ - -
The securing seat 20 has at least two hook-like : -
lS lugs 38 and a positioning pin 39 projecting from a
bottom side thereof. The wheel 17, light source 31 and
sensor 32 are positioned properly on the securing seat ---.-
20 before the securing seat 20 is mounted onto *he
circuit board 13 by means of the lugs 38 and positioning~
pin 39 which are individually inserted into insert holes
40 and a positioning hole 41 correspondingly formed in
the circuit board 13.
The light source 31 is disposed such that its light
is just perpendicular to the wheel 17, and the sensor 32
is located near the periphery of the wheel 17 for
receiving the light emitted by the light source 31 via
_ . .
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the periphery of the wheel 17. When the wheel 17
rotates, some of the light emitted by the light source
31 will be blocked by the wheel 17 while some will pass
via the periphery thereof to reach the sensor 32. These
two conditions may be respectively represented by 0 and
1. Therefore, when the wheel 17 performs continuous
rotation (whether clockwisely or counter-clockwisely),
four signals may be obtained: (1, 1), (0, 1), (0, 0) and
(1, 0). These signals are being converted via the
circuit board 13 to control the movement of a cursor.
Since there are provided two encoders 16, they may
respectively control the horizontal and vertical
movements of the cursor, which may move in whatever
direction across the screen.
The arrangement of the idle wheel 29 is to enable
the spindle 18 of the wheel 17 to be disposed at a
relatively higher position so that the diameter of the
wheel 17 mav be increased to achieve precise reading of
signals. In addition, the wheel 17 may be raised above
the circuit board 13 so that it may be mounted on the
circuit board 13 before the circuit board 13 undergoes
tin soldering. Furthermore, the wheel 17, light source
3 and sensor 32 may be fitted on the securing seat first
before the securing seat 32 is assembled to the circuit
board 13, thus achieving easy assembly and eliminating
the need for adjustment as in the prior art.
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Although the present invention has been illustrated
and described with reference to the preferred embodiment
thereof, it should be understood that it is in no way
limited to the details of such embodiment but is capable-
of numerous modifications within the scope of the
appended claims.
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