Transmitter receiver

Details Transmitter receiver Transmitter receiver

1999-02-02

2002-03-05

Lee, John R. (Department: 2878)

Radiant energy

Photocells; circuits and apparatus

Photocell controlled circuit

C250S553000

Reexamination Certificate

active

06353217

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmitter receiver which compares the intensities of light emitted by light-emitting portions provided with light-emitting diodes and detects a change in a relative inclination angle between a transmitting side and a receiving side, and in particular, to a transmitter receiver which can shield field inflection points of the light intensity distributions of the light-emitting portions.
2. Description of the Related Art
FIG. 6
is a perspective view of a pointer
1
of a wireless type which is used as a transmitter in the input device of a computer and can be operated by hand in a space.
FIG. 7
is a cross sectional view illustrating the light-emitting portion of the pointer land
FIG. 8
is a front view of the light-emitting portion of the pointer
1
.
The pointer
1
, as shown in
FIG. 8
, comprises five light-emitting diodes (hereinafter referred to as LED”)
2
a
,
2
b
,
2
c
,
2
d
, and
2
e
built in a box-shaped housing in a line, and the LEDs emit infrared light in previously determined order to freely move a cursor on the screen of a display in response to the movement of the pointer
1
.
The LED mounted in the light-emitting portion has a light-emitting directivity and, as shown in
FIG. 6
, a light-emitting central axis Oa of the LED
2
a
at the center faces the front (Z direction), where the light-emitting central axis is the direction in which the intensity of light emission is the largest, and the light-emitting central axes Ob and Oc of the LEDs
2
b
and
2
c
of the light-emitting portions formed in a pair at both ends are inclined inward (in the X direction) in the direction opposite to each other and are used to control the cursor in the right-left direction (in the X direction).
Further, the light-emitting central axes Od and Oe of the LEDs
2
d
and
2
e
of the remaining light-emitting portions formed in a pair are inclined in the up-down direction (in the Y direction) in the direction opposite to each other and are used to control the cursor in the up-down direction (in the Y direction).
In this pointer
1
, as shown in
FIG. 8
, five LEDs
2
a
,
2
b
,
2
c
,
2
d
and
2
e
emit light consecutively in pairs including central LED
2
a
, that is, LEDs
2
a
+
2
b
, LEDs
2
a
+
2
c
, LEDs
2
a
+
2
d
, LEDs
2
a
+
2
e
, in previously predetermined order, and the consecutive light emission is repeated cyclically at predetermined intervals.
A personal computer which is made a receiver is provided with a light-receiving portion
8
and, as shown in
FIG. 9
, a detecting section
9
for comparing the intensity of light received by the light-receiving portion
8
to detect a change in relative inclination angle of the pointer
1
between the transmitter and the receiver.
FIG. 9
shows a state in which the pointer
1
is inclined to the X (+) side with respect to the light-receiving portion
8
provided in the receiver.
Since the light-emitting central axes Ob and Oc of the LEDs
2
b
and
2
c
arranged in the right and left sides are inclined in the X direction in the direction opposite to each other, in the state in
FIG. 9
, the light-emitting central axis Ob of the LED
2
b
is inclined in the direction of the light-receiving portion
8
and the light-emitting central axis Oc of the LED
2
c
is inclined in the direction away from the light-receiving portion
8
. Therefore, the intensity of light received by the light-receiving portion
8
is stronger in the LEDs
2
a
+
2
b
than in the LEDs
2
a
+
2
c
. The detecting section
9
compares the intensities of light received by the light-receiving portions and calculates the amount of inclination of the pointer
1
in the X (+) direction, whereby the cursor on the screen of the personal computer is moved in the X (+) direction.
The inclination of the pointer
1
in the Y direction can be calculated in the same way by comparing the intensity of light emitted by the LEDs
2
a
+
2
d
with the intensity of light emitted by the LEDs
2
a
+
2
e.
FIG. 7
is a cross sectional plan view of a light-emitting portion arranged at the left end of the pointer
1
.
As shown in
FIG. 7
, the light-emitting portion provided with the LED
2
b
has a holder
1
a
formed of transparent resin at the front of the case of the pointer
1
, and the LED
2
b
is inserted from the back side into a projecting cover
1
b
integrally formed with the front of the holder
1
a
. The LED
2
b
comprises a light-emitting chip
6
arranged in the case
4
made of transparent resin and a reflecting plate
7
arranged at the back of the light-emitting chip
6
.
FIG. 9
schematically shows the light intensity distributions of the light-emitting portions provided with the LEDs
2
b
and
2
c
. The light intensity distributions Lb and Lc have peaks Pb
1
and Pc
1
on the light-emitting central axes Ob and Oc.
In the LED
2
b
, the case
4
and the cover
1
b
function as a lens to shape light-emitting fields in the direction of the axes Ob
1
and Oc
1
, which can enlarge the range of detection of inclination angle of the pointer
1
with respect to the Z axis and improve the quality of detection.
However, light leaking from the sides of the case
4
and the cover
1
b
shows field inflection portions Pb
2
and Pc
3
produced by reflection and refraction on the spherical surface and inclined surface of the case
4
and the cover
1
b.
The field inflection points Pb
2
and Pc
3
produced by the light leaking from an inclined side portion (i) that faces the direction of Z, that is, the direction of the light-receiving portion
8
, because the light-emitting central axes Ob and Oc are inclined, have a great effect on the angle detection intensity distribution. For example, in the state in
FIG. 9
, since the light-emitting central axis Ob of the LED
2
b
is greatly inclined in the Z direction, the intensity of light to the Z direction ought to decrease, but the light-receiving point
8
receives light stronger than inherent light from the LED
2
b
under the influence of the field inflection portion Pb
2
caused by light leaking from the inclined side portion (i).
Accordingly, when the detecting section
9
determines a difference in the intensity of light emission between the LED
2
b
and the LED
2
c
and calculates a relative inclination angle of the light-receiving portion
8
to the pointer
1
, it calculates an inclination angle different from the actual angle because of the field inflection point Pb
2
. Therefore, for example, there tends to be provided the problems that when the pointer
1
is inclined gradually in the X (+) direction from the Z direction, the cursor moving to the X (+) direction on the screen is suddenly moved opposite in the X (−) direction or is stopped on the way.
SUMMARY OF THE INVENTION
The present invention is made so as to solve the above-mentioned conventional problems. An object of the present invention is to provide a transmitter receiver which can detect a difference in the intensity of light emission between light-emitting portions without influence of the field inflection points of the light-emitting portions.
Another object of the present invention is to provide a transmitter receiver whose member for masking the light-emitting portions is hard to deviate in position where it masks the light-emitting portions.
The present invention provides a transmitter receiver comprising: a transmitter including pairs of light-emitting portions having directivity, the light-emitting portions being arranged such that the light-emitting central axes of each pair of light-emitting portions are inclined in the directions opposite to each other in the case where the light-emitting central axis is the direction in which the intensity of light emitted by the light-emitting portion is the strongest; a receiver including a light-receiving portion that receives light emitted by the pairs of light-emitting portions; and a detecting section that compares the intensities of light

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