X-Y Input device

An X-Y input device known as a "mouse" includes at least one switch lever having a control end exposed through an upper case and an opposite end staked on the upper case. An annular holder for the rotatable ball of the mouse is secured to a lower case and the switch lever has a portion close to the staked end held between the upper case and the annular holder.

BACKGROUND OF THE INVENTION 
The present invention relates to an X-Y input device, and more particularly 
to an X-Y input device suitable for use as an input device associated with 
a graphic display apparatus. 
Graphic display apparatus basically include a display screen, a display 
controller, a data channel, and an input device which may be of various 
types. One known input device is a "joystick" having a lever supported by 
a gimbal mechanism and tiltable by the operator in any direction. A 
control device detects the direction and angle of tilt of the lever and 
generates voltages or digital signals indicative of coordinate values in X 
and Y directions. This type of input device is disadvantageous however in 
that the range of angular movement of the lever is limited and data 
signals entered by the operator are relatively unstable. 
In an effort to eliminate the above shortcomings, there has in recent years 
been developed an input device called a "mouse." One type of the mouse has 
a rotatable member such as a steel ball, and first and second driven 
rollers held in contact with the ball are rotated in response to rotation 
thereof. The first and second driven rollers have their axes of rotation 
extending substantially perpendicularly to each other. The mouse also 
includes first and second angle detector means often comprised of variable 
resistors or encoders for separately detecting the angles of rotation of 
the first and second driven rollers. The ball, first and second driven 
rollers, and first and second angle detector means are all housed in a 
casing. 
The casing has an opening defined in its bottom with the ball partly 
projecting through the opening. In use, the casing is held by the operator 
to place the ball against a given base or surface. By moving the casing to 
cause the ball to roll on the surface in any desired direction, the first 
and second driven rollers are rotated about their own axes through angles 
dependent on the rolling movement of the ball. The directions and angles 
of rotation of the driven rollers are converted by the first and second 
angle detector means into voltages or digital signals corresponding to the 
rolling movement of the ball representative of coordinate values in X and 
Y directions. The generated signals are then entered into a display 
apparatus. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an X-Y input device of 
the type known as a mouse, which includes a casing having a rotatable ball 
and switch levers staked on an upper casing and held between the upper 
casing and an annular holder for the ball. In this way, the switch levers 
are held securely to effect stable switching operation even when the 
staked portions deteriorate in strength. 
According to the present invention, there is provided an X-Y input device 
including a rotatable ball, and first and second driven rollers held in 
contact with the rotatable ball and rotatable in response to rotation of 
the rotatable ball for actuating respective detector means signalling the 
movement of the ball in X and Y coordinates. A casing for the X-Y input 
device has a lower opening through which the ball partially projects for 
rolling movement on a base and at least one switch lever is provided with 
an actuating portion exposed through the upper case and an opposite end 
staked on the upper case. The switch lever has a portion close to the 
staked end and sandwiched between the upper case and a dome-shaped holder 
for the rotatable ball. 
The above and other objects, features and advantages of the present 
invention will become more apparent from the following description when 
taken in conjunction with the accompanying drawings in which a preferred 
embodiment of the present invention is shown by way of illustrative exampl 
e

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows in perspective a graphic display apparatus incorporating 
therein an X-Y input device according to the present invention. 
The graphic display apparatus illustrated in FIG. 1 comprises a display 
unit 2 mounted on a table 1 and having a screen, a controller, a data 
channel, an input device 3 having function keys, and an X-Y input device 4 
according to the present invention. The X-Y input device 4 is operated by 
the operator on a sheet 5 placed on the table 1 to move a cursor 7 to any 
desired position on a screen 6 of the display unit 2. 
FIG. 2 shows the X-Y input device 4 in its side elevation. 
The X-Y input device 4 has a casing 8 comprised of a lower case 9 and an 
upper case 10, the lower and upper cases 9 and 10 being molded of an ABS 
resin. The upper and lower cases 9 and 10 have stepped mating peripheral 
edges held in interfitting engagement with each other to prevent dust, 
water and other foreign matter from entering into the casing 8 through the 
joint between the lower case 9 and the upper case 10. 
The upper case 10 is of a size which can be held by one hand of the 
operator. The upper case 10 includes an upper wall 11 having elongate 
slots 12 defined in a front position thereon and extending longitudinally 
of the uper case 10. Rectangular switch levers 13 are disposed in the 
casing 8, and have actuating portions 14 fitted repsectively in the slots 
12 within the upper case 10 and projecting slightly through the upper wall 
11. 
As described below, pushbutton switches are located below respective switch 
levers 13 for deleting a portion of a displayed pattern immediately above 
or below the cursor 7, moving such a displayed pattern portion to another 
location, or effecting various other signal processing modes such as 
switching and control on the display unit 2. The displayed pattern can 
also be processed by the input device 3 itself. The display unit 2 and the 
X-Y input device 4 are interconnected by a cord 15 and a plug 16. 
FIGS. 3 through 5 illustrate the lower case 9. The lower case 9 includes a 
bottom wall having an upstanding peripheral wall 18 extending continuously 
along the outer peripheral edge thereof. The bottom wall has small holes 
19 and 20 at two front corners and a rear central portion thereof. The 
three holes 19, 20 and 21 are positioned such that an isosceles triangle 
would be formed by lines interconnecting the centers of these three holes 
19, 20 and 21. 
The bottom wall also has a central larger-diameter opening 22 and an 
annular step 22a formed along a lower edge of the larger-diameter opening 
22. A rectangular recess 22b is defined in a portion of the lower edge of 
the opening 22. Four threaded holes 23 are defined in the bottom wall 
around the opening 22. 
Holes 24, 25 and 26 for receiving screws are defined in the bottom wall at 
the front central portion and two rear corners thereof. The bottom wall 
also includes integral stiffener ribs 27 extending between the 
screw-insertion hole 24, the opening 22, and the peripheral wall 18. 
FIGS. 6 through 8 shown an annular holder 28 on which a rotatable ball is 
held. 
The annular holder 28 is integrally molded of synthetic resin and has a 
central cavity 29 having an inside diameter larger than the diameter of 
the rotatable ball, and three recesses 30, 31 and 32 defined around the 
central cavity 29. The recesses 30, 31 and 32 serve to hold the position 
the driven rollers and frictional-force imposing roller and open into the 
central cavity 29. 
The annular holder 28 has an integral dome-shaped protective cover 33 
extending over the central cavity 29 for preventing the rotatable ball 
from wobbling in the cavity 29. T-shaped projections 34 are disposed on an 
upper surface of the protective cover 33 and serve as seats 34 against 
which lower surfaces of the switch levers 13 bear, the T-shaped 
projections 34 providing top surfaces of the annular holder 28, as shown 
in FIG. 8. 
As illustrated in FIG. 6, the annular holder 28 has four threaded holes 35 
defined in lateral sides of the recess 30 and ends of the recesses 31 and 
32. The annular holder 28 can be fastened to the lower case 9 by screws 
extending threadedly into the threaded holes 23 in the lower case 9. 
FIGS. 9 through 11 show the upper case 10. The upper wall 11 of the upper 
case 10 has an upwardly convex curved configuration such that it can be 
held in the hand of the user. The upper wall 11 has windows 36 defined in 
front portions thereof through which the actuating portions 14 of the two 
switch levers 13 extend. The upper wall 11 has threaded holes 37, 38 and 
39 defined in inner surfaces thereof in registry with the screw-insertion 
holes 24, 25 and 26, respectively, in the lower case 9. The upper wall 11 
also has recessed bosses 40, 41 and 42 formed on inner surfaces thereof in 
registry with the holes 19, 20 and 21, respectively, in the lower case 9. 
The upper wall 11 also has an annular ridge 43 formed on an inner surface 
thereof in registry with the opening 22 in the lower case 9 and held in 
abutment against an upper surface of the protective cover 33 of the 
annular holder 28 to press the protective cover 33 downwardly for 
reinforcing the same. The upper wall 22 includes two integral T-shaped 
pressers 44 identical in shape to and in registry with the seats 34 on the 
annular holder 28. The switch levers 13 are fixed in position by two sets 
of three fused pins 45 adjacent to the pressers 44 and their ends being 
sandwiched between the pressers 44 and the seats 34. 
The upper case 10 has a peripheral wall 46 extending along an outer 
peripheral edge thereof. The upper case 10 also has integral stiffener 
ribs 47 extending between the peripheral wall 46, the bosses 40, 41 and 
42, and the threaded holes 37, 38 and 39. 
FIGS. 13 through 15 illustrate one of the switch levers 13, the two switch 
levers 13 being of an identical configuration. 
The switch lever 13 is integrally molded of synthetic resin and has an 
angularly bent cross section. The end forming the actuating portion 14 is 
generally cup-shaped and has a top wall from which an actuator 14a extends 
obliquely downwardly. The other end of the switch lever 13 has a narrower 
pinched portion 48, three small holes 49 defined therein and located 
inwardly of the pinched portion 48, and a thinned portion 50 located 
inwardly of the three small holes 49 for allowing the switch lever 13 to 
operate easily. The acutating portion 14 has a flange 14b directed away 
from the actuator 14a for abutment against an edge of the inside of the 
window 36 so as to serve as a stop against return movement of the switch 
lever 13 after it has been depressed. The switch lever 13 also includes 
stiffener ribs 51 formed on bent portions thereof. 
FIG. 16 shows the X-Y input device 4 as assembled. 
The lower case 9 and the upper case 10 are fastened to each other by screws 
threaded through screw holes 24, 25 and 26 into the threaded holes 37, 38 
and 39. The rotatable ball, designated at 53, is made of steel and 
disposed centrally in the casing 8. The ball 53 is retained in the casing 
8 by the annular holder 28 and a cover 54 fitted in the step 22a around 
the opening 22 and secured to the lower case 9 by screws (not shown). The 
ball 53 has a lower end exposed downwardly through an opening in the cover 
54 and is rotatable within the cavity 29 in the annular holder 28 by 
rolling movement on the base 5 (FIG. 1). 
The two switch levers 13 are fixed at end portions thereof to the upper 
wall of the upper case 10 by the fused pins 45. More specifically, each 
switch lever 13 can be fixed in position by inserting the three pins 45 
through the holes 49 in the switch lever 13 and then fusing and staking 
the distal ends of the pins 45. With the switch levers 13 thus fastened, 
the actuating portions 14 are angularly movable about their staked 
portions under their own resiliency. As shown in FIG. 17, the pinched 
portion 45 of each switch lever 13 which is located closely to the staked 
portion thereof is sandwiched between the seat 34 on the annular holder 28 
and the corresponding presser 44 on the upper wall of the upper case 10. 
This allows the switch lever 13 to remain resiliently angularly movable 
about the staked portion even if the staked portion deteriorates in its 
strength of attachment. 
The pushbutton switch, denoted at 56 in FIG. 17, is operated by the switch 
lever 13, and mounted on a substrate 57 secured to the upper end of a boss 
58 (FIG. 16) of the lower case 9. The actuator 14a of the switch lever 13 
is disposed in confronting relation to the pushbutton switch 56. When the 
actuating portion 14 is depressed by the user, the actuator 14a engages 
the pushbutton switch 56 to enable the same to effect desired switching 
operation. 
Under normal conditions of use, the dome-shaped protective cover 33 of the 
annular holder 28 is slightly spaced from an upper surface of the ball 53 
and does not obstruct rolling movement of the ball 53. When the X-Y input 
device 53 is turned over or dropped, the protective cover 33 prevents the 
ball 53 from moving toward the upper case 10. Accordingly, the surfaces of 
the ball 53 and the upper case 10 are protected against unwanted damage. 
Since the rotation of the ball 53 should be detected accurately, the ball 
53 usually comprises a steel ball, as described above, which is heavy and 
provides a highly accurate surface. If the ball 53 were allowed to contact 
the inner surface of the upper case, the surface of the ball 53 could be 
damaged and accurate and stable detection of the rotation of the ball 53 
would not be possible. To prevent such a problem, an upper portion of the 
ball 53 is covered with the dome-shaped protective cover 33 which has a 
curvature close to that of the ball 33. 
The principle of operation of the X-Y input device for detecting rotation 
of the ball 43 will be described with reference to FIG. 18. 
The ball 53 is pressed against first and second driven rollers 59 and 60 by 
a frictional-force imposing roller 61. The first and second driven rollers 
59 and 60 have axes extending perpendicularly to each other and are kept 
in contact with the peripheral surface of the ball 53 in mutually 
perpendicular directions. The frictional-force imposing roller 61 is 
located on a straight line passing through a point Q where the axes of the 
first and second driven rollers 59 and 60 intersect and the center O of 
the ball 53 for pressing the ball 53 against the first and second driven 
rollers 59 and 60 under equal forces. The frictional-force imposing roller 
61 is rotatably supported by a casing 62 biased by a spring 63 for 
resiliently pressing the ball 53 against the first and second driven 
rollers 59 and 60. 
The first and second driven rollers 59 and 60 have shafts on which first 
and second rotation detector means 64 and 65 are mounted respectively. The 
first and second rotation detector means 64 and 65 include encoders, 
rotary variable resistors, and other components for detecting the 
rotations of the driven rollers so that the rotation of the ball 53 can be 
detected as components in the X- and Y-axis directions to thereby 
determine the manner in which the ball 53 rotates. 
Although a certain preferred embodiment has been shown and described, it 
should be understood that many changes and modifications may be made 
therein without departing from the scope of the appended claims.