Portable input apparatus

A portable input apparatus used in conjunction with a controllable information processing apparatus which comprises a light receiving element receiving a base light emitted from a light emitting section of the controllable information processing apparatus and being composed of a first detector light receiving element, a second detector light receiving element and a reference light receiving element arranged therebetween, each being of a non-split type; an optical signal transmitting section transmitting an optical signal to the controllable information processing apparatus side; signal conversion sections converting an output current of the non-split type light receiving element and generating a time shared output voltage; a signal processing section processing the time shared output voltage to generate relative angle data; and a control section performing operation and calculation of the relative angle data to form a coordinate signal and transmitting the optical signal including the coordinate signal to the controllable information processing apparatus side.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a portable input apparatus which is used 
in conjunction with a controllable information processing apparatus, more 
particularly, to a portable input apparatus such that a base light emitted 
from a light emitting section of the controllable information processing 
apparatus is received by non-split type three light receiving elements. 
2. Description of the Related Art 
A relative angle detection apparatus has already been proposed by the 
assignee of this application. In the relative angle detection apparatus, a 
light emitting section is arranged on a controllable information 
processing apparatus side such as a computer and a game apparatus, and 
split light receiving sections are arranged on a portable input apparatus 
side. The light emitted from the light emitting section of the 
controllable information processing apparatus side is received by the 
split light receiving elements of the portable input apparatus side. A 
relative angle between the light emitting section and the split light 
receiving elements, i.e. a relative angle between the controllable 
information processing apparatus and the portable input apparatus is 
detected according to an electric signal obtained by the split light 
receiving elements, and the detection results are displayed on a display 
section of the controllable information processing apparatus (hereinafter, 
the relative angle detection apparatus is referred to as the proposed 
relative angle detection apparatus). 
FIG. 4 is a block diagram showing an example of the proposed relative angle 
detection apparatus (portable input apparatus) in which the controllable 
information processing apparatus is a computer. 
As shown in FIG. 4, a computer (controllable information processing 
apparatus) 31 comprises a CRT (cathode ray tube) 33 for displaying images, 
a light emitting section 32 to be arranged on a peripheral portion, such 
as the upper portion of the CRT 33 and an optical signal receiving section 
34. A portable input apparatus 35 has a shape of a rectangular 
parallelepiped, and a detecting section (not shown) is provided on the 
front thereof. The detecting section consists of split light receiving 
element 36 including four-part split light receiving sections 36a to 36d 
each being formed of, for example, a photodiode, a diaphragm (not shown) 
having a rectangular opening and a visible light cut-off filter (not 
shown) each being arranged on the front side of the split light receiving 
element 36. Among the four-part split light receiving sections 36a to 36d, 
the light receiving sections 36b and 36d are connected to a 
current-voltage (I-V) converter 37a so that output currents thereof are 
added, and the light receiving sections 36a and 36c are connected to a 
current-voltage (I-V) converter 37b so that output currents thereof are 
added. In addition, the light receiving sections 36a and 36b are connected 
to a current-voltage (I-V) converter 37c so that output currents thereof 
are added, and the light receiving sections 36c and 36d are connected to a 
current-voltage (I-V) converter 37d so that output currents thereof are 
added. The outputs of the I-V converters 37a to 37d are connected to fixed 
contact terminals side of a selector switch 38 having one circuit and four 
contacts, and a movable contact terminal of the selector switch 38 is 
connected to an input of a signal processing section 40. The selector 
switch 38 is connected to a switching controller 39 and switching 
operation of the contacts is performed by the control of the switching 
controller 39. The signal processing section 40 includes inside thereof a 
variable gain amplifier, a band-pass filter (BPF) circuit, a peak holding 
circuit such as a sample-hold (S/H) circuit and an analog-digital (A/D) 
converter, and outputs thereof are connected to a control section 42. An 
output of the BPF circuit in the signal processing section 40 is connected 
to an input of a waveform shaping circuit 41 and an output of the waveform 
shaping circuit 41 is connected to the control section 42. The control 
section 42 is connected to the switching controller 39 and the optical 
signal transmitting section 43. The optical signal transmitting section 43 
includes a plurality of light emitting elements which emit lights of an 
infrared region. 
With respect to three directions represented by rectangular three 
dimensional coordinates, if the lengthwise direction of the portable input 
apparatus 35 is taken as Z-axis direction and each of two directions 
orthogonal to the Z-axis are taken as X-axis direction and Y-axis 
direction, the four-part split light receiving sections 36a to 36d are 
arranged so that the light receiving sections 36a and 36b, and 36c and 36d 
are aligned in the X-axis direction and the light receiving sections 36a 
and 36c, and 36b and 36d are aligned in the Y-axis direction. 
The proposed relative angle detection apparatus (portable input apparatus) 
constructed as described above is operated as follows. 
When an operator has the portable input apparatus 35 in hand and points the 
detecting section side thereof toward a CRT 33 (a light emitting section 
32), a base light of the infrared region having a frequency f emitted from 
the light emitting section 32 is incident in the detecting section of the 
portable input apparatus 35. The incident base light is first subjected to 
the elimination of a visible light component with a visible light cut-off 
filter (not shown), and then to the adjustment of an amount of incidence 
with a diaphragm (not shown) and thereafter, applied to the four-part 
split light receiving sections 36a to 36d which constitute the split light 
receiving elements 36. At this time, a rectangular spot light defined by 
the opening of the diaphragm is applied to the four-part split light 
receiving sections 36a to 36d, and current outputs I.sub.LU, I.sub.RU, 
I.sub.LD, and I.sub.RD corresponding to application areas of the spot 
light are output from the four-part split light receiving sections 36a and 
36d. Each of these current outputs I.sub.LU, I.sub.RU, I.sub.LD, and 
I.sub.LD include a frequency f which is a main component of the base 
light. Then, the sum of the current outputs (I.sub.RU +I.sub.RD) obtained 
by one set of the light receiving sections 36a and 36c arranged in the 
Y-axis direction is supplied to the I-V converter 37a, and the sum of the 
current outputs (I.sub.LU +I.sub.LD) obtained by the other set of the 
light receiving sections 36b and 36d arranged in the Y-axis direction is 
supplied to the I-V converter 37b, respectively. In addition, the sum of 
the current outputs (I.sub.LU +I.sub.RU) obtained by one set of the light 
receiving sections 36a and 36b arranged in the X-axis direction is 
supplied to the I-V converter 36c, and the sum of the current outputs 
(I.sub.LD +I.sub.RD) obtained by the other set of the light receiving 
sections 36c and 36d mounted in the X-axis direction is supplied to the 
I-V converter 37d, respectively. Each of the I-V converters 37a to 37d 
convert the input current into the output voltage and allow channels 1 to 
4 to generate light receiving output voltages V1 to V4. Then, the light 
receiving output voltages V1 to V4 are supplied to the selector switch 38. 
The movable contacts of the selector switch 38 are switched on a 
predetermined cycle by the switching controller 39 which operates in 
response to a switching signal supplied from the control section 42 in 
order of channel 1, channel 2, channel 3, channel 4, channel 1, channel 2 
... . Thus, the light receiving output voltages V1 to V4 become time 
shared output voltages selected by the selector switch 38 in a time 
sharing manner, and the time shared output voltages are supplied to the 
signal processing section 40. The time shared output voltages supplied to 
the signal processing section 40 are amplified in the variable gain 
amplifier by a gain corresponding to a gain control voltage supplied from 
the control section 42 and then, unnecessary frequency components except 
for the frequency f are eliminated in the BPF circuit. In addition, a 
signal having the frequency f output from the BPF circuit is subjected to 
sampling and held in the S/H circuit and then, the sampling voltage is 
converted into a digital signal in the A/D converter. The digital signal 
is supplied to the control section 42 as relative angle data. 
In the signal processing section 40, the signal having the frequency f 
output from the BPF circuit is supplied to the waveform shaping circuit 
41. The waveform shaping circuit 41, under the control of the control 
section 42, generates a trigger pulse and the like when the signal having 
the frequency f reaches the peak voltage in a stable condition after a 
channel switching of the selector switch 38 is performed. The control 
section 42 supplies a timing pulse and the like instructing the start and 
end of the sampling to the S/H circuit in response to the trigger pulse 
and the like, and supplies a timing pulse and the like instructing the 
start and end of the digital conversion to the A/D circuit. 
Therefore, the S/H circuit starts sampling of the signal having the 
frequency f output from the BPF circuit with the timing pulse supplied 
from the control section 42 and holds the sampling voltage obtained by the 
sampling. When several periods of the signal output from the BPF circuit 
having the frequency f elapses after the channels are switched by the 
selector switch 39, the sampling voltage indicates the stable peak voltage 
in one period of the signal. The A/D converter converts the sampling 
voltage held in the S/H circuit into a digital signal with the timing 
pulse supplied from the control section 42, and the obtained digital 
signal is supplied to the control section 42 as the relative angle data. 
The control section 42 performs operations of the relative angle data which 
are sequentially supplied in response to a switching of the selector 
switch 38. The operations are represented by {(V1p-V2p)/(V1p+V2p)} and 
{(V3p-V4p)/(V3p+V4p)} where V1p, V2p, V3p and V4p are relative angle data 
(digital peak voltage) derived from the light receiving output voltages 
V1, V2, V3 and V4, respectively. A tilt angle .theta.x of the portable 
input apparatus 35 in the X-axis direction is determined by the former 
operation and a tilt angle .theta.y of the portable input apparatus 35 in 
the Y-axis direction is determined by the latter operation. In addition, 
the control section 42 performs coordinate calculation with the converted 
distance on the X-Y coordinates of a display surface of the CRT 33 
according to the obtained angles .theta.x and .theta.y to generate a 
coordinate signal, and supplies the coordinate signal to the optical 
signal transmitting section 43. The optical signal transmitting section 43 
transmits the optical signal of the infrared region including the 
coordinate signal to the light receiving section 34 of the computer 31 
side by lighting a plurality of light emitting elements. The optical 
signal receiving section 34 performs display on the required position of 
the display surface of the CRT 33 in the form of a cursor mark according 
to the coordinate signal in the optical signal received therein. 
In this case, when the operator suitably moves the detecting section of the 
portable input apparatus 35 in the direction substantially parallel to the 
display surface of the CRT 35, or suitably changes the angle of the 
portable input apparatus 35 with respect to the display surface, the tilt 
angle .theta.x in the X-axis direction and the tilt angle .theta.y in the 
Y-axis direction of the portable input apparatus 35 may be changed 
occasionally, and the position of the cursor mark to be displayed on the 
display surface of the CRT 33 may be changed occasionally with changes of 
the tilt angles. 
The proposed relative angle detection apparatus can effectively move the 
position of the cursor mark to be displayed on the CRT 33 of the computer 
31 by suitably changing the position of the portable input apparatus 35 
with respect to the computer 31. However, the base light from the light 
emitting section 32 of the computer 31 is received by the split light 
receiving element 36 which is split into, for example, four light 
receiving sections 36a to 36d. Thus, the cost of manufacturing the split 
light receiving element 36 and peripheral devices thereof may be increased 
for the following reasons: it is relatively difficult to manufacture the 
split light receiving element 36; the commonly used light receiving 
element is not split and the split light receiving element 36 has no 
versatility; and additional mounting substrates are required when the 
split light receiving element 36 is mounted on the main substrate of the 
portable input apparatus 35 side. In addition, when the current outputs 
obtained by the four light receiving sections 36a to 36d are converted 
into time shared output voltages in the signal conversion section, the 
magnitude of the current outputs and transient response caused at the time 
of switching of the output voltages must be taken into consideration in 
order to adjust output timings of the time shared output voltages. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a portable input 
apparatus which reduces the cost of manufacturing the portions in relation 
to the light receiving element and by which excellent sound-to-noise ratio 
is obtained without consideration of the current outputs of the light 
receiving elements. 
To achieve the above object, the present invention provides a portable 
input apparatus used in conjunction with a controllable information 
processing apparatus which comprises a means including a light receiving 
element receiving a base light emitted from a light emitting section of 
the controllable information processing apparatus and being composed of a 
first detector light receiving element, a second detector light receiving 
element and a reference light receiving element arranged therebetween, 
each being of a non-split type; an optical signal transmitting section 
transmitting an optical signal to the controllable information processing 
apparatus side; a signal conversion section converting an output current 
of the light receiving element and generating a time shared output 
voltage; a signal processing section processing the time shared output 
voltage to generate relative angle data; and a control section performing 
operation and calculation of the relative angle data to form a coordinate 
signal and transmitting the optical signal including the coordinate signal 
to the controllable information processing apparatus. 
In this case, the above signal conversion section includes a first 
additional means which consists of first and second division circuits each 
dividing output currents of the first and second detector light receiving 
elements by an output current of the reference light receiving element; 
first and second current-voltage converters each converting output 
currents of the first and second division circuits into voltages; a third 
current-voltage converter converting an output current of the reference 
light receiving element into a voltage; and a switching circuit adding 
output voltages of the first to third current-voltage converters in a time 
sharing manner, and a second additional means in which a lateral part of a 
light receiving surface of the first detector light receiving element is 
shielded and a longitudinal part of a light receiving surface of the 
second detector light receiving element is shielded, respectively and in 
which the size of the light receiving surface of the reference light 
receiving element is smaller than each size of the light receiving surface 
of the first and second detector light receiving elements. 
In addition, the above signal conversion section includes a third 
additional means which consists of an adder adding each of output currents 
of the first detector light receiving element, the second detector light 
receiving element and the reference light receiving element; a subtracter 
subtracting an output current of the second detector light receiving 
element from an output current of the first detector light receiving 
element; and adder-subtracter adding the output current of the first 
detector light receiving element to the output current of the second 
detector light receiving element and then, subtracting an output of the 
reference light receiving element; first to third current-voltage 
converters each converting the output currents of the adder, subtracter 
and adder-subtracter into voltages; and a switching circuit adding output 
voltages of the first to third current-voltage converters in a time 
sharing manner, and a fourth additional means in which each of lateral 
parts of light receiving surfaces of said first detector light receiving 
element and said second detector light receiving element are shielded in 
the oblique and different directions to each other, and in which a 
longitudinal part of the light receiving surface of said reference light 
receiving element is shielded. 
In the above-described means, the first detector light receiving element, 
the second detector light receiving element and the reference light 
receiving element, each of being a non-split type rather than a split 
type, are used as the light receiving elements in the portable input 
apparatus side which receive the base light emitted from the light 
emitting section of the controllable information apparatus. 
Therefore, according to the above-described means, the light receiving 
elements can be manufactured with relative ease and mounted on the main 
substrate of the portable input apparatus side without the use of 
additional mounting substrates, thereby reducing the manufacturing cost 
compared with a case where the split light receiving elements are used. 
In addition, according to the above-described means, since lots of the base 
light are incident at all times in the reference light receiving element 
arranged between the first and the second light receiving elements, the 
output current from the reference light receiving element is maximum. 
However, if the size of a light receiving surface of the reference light 
receiving element is made smaller than each size of the light receiving 
surface of the first and the second detector light receiving elements, 
signal level becomes relatively high at the time of normalization of each 
of the output currents of the first and second detector light receiving 
elements. Thus, excellent signal-to-noise ratio can be obtained, thereby 
obtaining stable normalized output currents. At the same time, the 
difference between the normalized output currents of the first and second 
detector light receiving elements can be reduced. Therefore, accurate time 
shared output voltages can be obtained without consideration of transient 
response caused when switching of the time shared output voltages, and a 
return phenomenon of the cursor mark (a phenomenon in which the cursor 
mark moves in the opposite direction to the movement of the portable input 
apparatus) on the periphery of a display screen can be prevented.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiments of the present invention will now be described 
with reference to the accompanying drawings. 
FIG. 1 is a block diagram showing a first embodiment of a portable input 
apparatus according to the present invention which includes a relative 
angle detection apparatus together with a controllable information 
processing apparatus comprising a computer. 
Here, the difference in structure between the relative angle detection 
apparatus (portable input apparatus) of the first embodiment and the above 
proposed relative angle detection apparatus (portable input apparatus) 
will be described. In the relative angle detection apparatus of the first 
embodiment, a first detector light receiving element, a second detector 
light receiving element and a reference light receiving element, each of 
which is an non-split type light receiving element, are used as the light 
receiving element of the portable input apparatus side, while a light 
receiving element comprising four-part split light receiving sections are 
used in the proposed relative angle detection apparatus. In addition, two 
division circuits and three current-voltage converters are used in the 
relative angle detection apparatus of the first embodiment, while four 
current-voltage converters are used in the proposed relative angle 
detection apparatus. In order to define configuration of the first 
embodiment, the overall structure of the relative angle detection 
apparatus of the first embodiment will be described including the same 
components as those of the proposed relative angle detection apparatus. 
As shown in FIG. 1, a computer (controllable information processing 
apparatus) 1 comprises a CRT 3 for displaying images, a light emitting 
section 2 to be arranged on a peripheral portion, such as the upper 
portion, of the CRT 3 and an optical signal receiving section 4. A 
portable input apparatus 5 has a shape of a rectangular parallelepiped, 
and a detecting section (not shown) is provided on the front thereof. The 
detecting section is formed of a photodiode, and arranged on the front 
sides of light receiving element 6 composed of a first detector light 
receiving element 6a, a second detector light receiving element 6b and a 
reference light receiving element 6c arranged therebetween, each being of 
a non-split type, and arranged at each front side of the light receiving 
elements 6a to 6c. The detecting section consists of a diaphragm (not 
shown) having a rectangular opening and a visible light cut-off filter 
(not shown). In this case, the size of the light receiving surface of the 
reference light receiving element 6c is smaller than each size of the 
light receiving surface of the first and second detector light receiving 
elements 6a and 6b. A substantially lateral half portion of the first 
detector light receiving element 6a is shielded by a shielding member 6as 
and a substantially longitudinal half portion of the second detector light 
receiving element 6b is shielded by a shielding member 6bs. Outputs of the 
first detector light receiving element 6a and the reference light 
receiving element 6c are connected to a first division circuit 7a, and 
outputs of the second detector light receiving element 6b and the 
reference light receiving element 6c are connected to a second division 
circuit 7b. The output of the first division circuit 7a is connected to a 
first current-voltage (I-V) converter 8a, the output of the second 
division circuit 7b is connected to a second current-voltage (I-V) 
converter 8b and the output of the reference light receiving element 6c is 
connected to a third current-voltage (I-V) converter 8c. The outputs of 
the first to third I-V converters 8a to 8c is connected to a fixed contact 
terminals side of a selector switch (switching circuit) 9 having one 
circuit and three contacts and a movable contact terminal of the selector 
switch 9 is connected to an input of the signal processing section 11. The 
selector switch 9 is connected to a switching controller 10 and a 
switching operation of the contacts is performed by the control of the 
switching controller 10. The portion including the first and second 
division circuits 7a and 7b, the first to third I-V converters 8a to 8c 
and the selector switch 9 forms a signal conversion section. The signal 
processing section 11 includes inside thereof a variable gain amplifier, a 
band-pass filter (BPF) circuit, and a peak holding circuit such as a 
sample-hold (S/H) circuit and an analog-digital (A/D) converter, and 
outputs thereof are connected to a control section (CPU) 13. An output of 
the BPF circuit in the signal processing section 11 is connected to an 
input of a waveform shaping circuit 12, and an output of the waveform 
shaping circuit 12 is connected to the control section 13. The control 
section 13 is connected to the switching controller 10 and a optical 
signal transmitting section 14. The optical signal transmitting section 14 
includes a plurality of light emitting elements such as light emitting 
diodes (LEDs) which emit lights of an infrared region. 
With respect to three directions represented by rectangular three 
dimensional coordinates, if the lengthwise direction of the portable input 
apparatus 5 is taken as Z-axis direction and each of two directions 
orthogonal to the Z-axis are taken as X-axis direction and Y-axis 
direction, respectively, the shielding member 6as of the first detector 
light receiving element 6a is provided so as to shield a portion of the 
light receiving surface in the longitudinal, i.e. X-axis direction, and 
the shielding member 6bs is provided so as to shield a portion of the 
light receiving surface in the lateral, i.e. Y-axis direction. 
The relative angle detection apparatus (portable input apparatus) of the 
first embodiment constructed as described above is operated as follows. 
The relative angle detection apparatus (portable input apparatus) of the 
first embodiment differs from the proposed relative angle detection 
apparatus only in the operation mode when the current output obtained from 
the receipt of the base light by the light receiving elements (split light 
receiving elements) 6 is processed by the signal processing section to 
obtain a time shared output voltage. However, in order to define the 
operation of the relative angle detection apparatus (portable input 
apparatus) in the first embodiment, the overall operation thereof will be 
described including overlapping sections in the operation of the proposed 
relative angle detection apparatus (portable input apparatus). 
When an operator has the portable input apparatus 5 in hand and points the 
detecting section side thereof toward a CRT 3 (a light emitting section 2) 
of the computer 1, the base light of the infrared region having a 
frequency of f emitted from a light source of the light emitting section 2 
is incident in the detecting section of the portable input apparatus 5. 
The incident base light is subjected to the elimination of a visible light 
component with the visible light cut-off filter (not shown) and then, 
subjected to the adjustment of an amount of incidence with a diaphragm 
(not shown) and thereafter, the incident base light is applied to the 
first detector receiving element 6a, the second detector receiving element 
6b and the reference light receiving element 6c , respectively. At this 
time, a rectangular spot light defined by the opening of the diaphragm is 
applied to each of the light receiving elements 6a to 6c, and current 
outputs Ia, Ib and Ic corresponding to application areas of the spot light 
are output from each of the light receiving elements 6a to 6c . Each of 
the current outputs Ia, Ib and Ic include frequency f which is a major 
component of the base light. Then, the first division circuit 7a receives 
and calculates the current outputs Ia and Ic to output a first current 
division output Ia/Ic, and the second division circuit 7b receives and 
calculates the current outputs Ib and Ic to output a second current 
division output Ib/Ic. Consecutively, the first current division output 
Ia/Ic is supplied to the first I-V converter 8a, the second current 
division output Ib/Ic is supplied to the second I-V converter 8b and the 
current output of the reference light receiving element 6c is supplied to 
the third I-V converter 8c, respectively. Each of the first to third I-V 
converters 8a to 8c convert the input current into the output voltages and 
allow the outputs of the first to third I-V converters 8a to 8c to 
generate light receiving output voltages V1 to V3 of 1 to 3 channels, 
respectively. 
These light receiving output voltages V1 to V3 are supplied to the selector 
switch 9. The movable contacts of the selector switch 9 are switched on a 
predetermined cycle by the switching controller 10 which operates in 
response to a channel switching signal supplied from the control section 
13 in order of channel 1, channel 2, channel 3, channel 1, channel 
2...(first switching mode) or switched in order of channel 1, channel 2, 
channel 1, channel 2...(second switching mode). The light receiving output 
voltage V3 of the channel 3 showing the current output of the reference 
light receiving element 6c becomes necessary for some controls performed 
in the control section 13 with the amount of incidence of the base light. 
Thus, the selector switch 9 operates in the first switching mode. On the 
other hand, when the light receiving output voltage V3 is not necessary 
for any controls in the control section 13 with the amount of incidence of 
the base light, the selector switch 9 operates in the second switching 
mode. The light receiving output voltages V1 to V3, or V1 to V2 are 
selected in a time sharing manner to become time shared output voltages, 
and the time shared output voltages are supplied to the signal processing 
section 11. The time shared output voltages supplied to the signal 
processing section 11 are amplified in the variable gain amplifier by a 
gain corresponding to a gain control signal supplied from the control 
section 13 and then, unnecessary frequency components except for the 
frequency f are eliminated in the BPF circuit. In addition, a signal 
having the frequency f output from the BPF circuit is subjected to 
sampling and held in the S/H circuit and then, the sampling voltage is 
converted into the digital signal. The digital signal is supplied to the 
waveform shaping circuit 12 as relative angle data. 
The control section 13 performs operations of the relative angle data which 
are sequentially supplied in response to a switching of the selector 
switch 9. The operations are represented by {V1p/(V1p+V2p)} and 
{V2p/(V1p+V2p)} in which V1p and V2p are relative angle data (digital peak 
voltage) derived from the light receiving output voltages V1 and V2, 
respectively. A tilt angle .theta.x of the portable input apparatus 5 in 
the X-axis direction is determined by the former operation and a tilt 
angle .theta.y of the portable input apparatus 5 in the Y-axis direction 
is determined by the latter operation. In addition, the control section 13 
performs coordinate calculation with the converted distance on the X-Y 
coordinates of a display surface of the CRT 3 according to the obtained 
angles .theta.x and .theta.y to generate a coordinate signal, and supplies 
the coordinate signal to the optical signal transmitting section 14. The 
optical signal transmitting section 14 transmits the optical signal 
including coordinate signal to the light receiving section 3 of the 
computer 1 side. The computer 1 performs display on the required position 
of the display surface of the CRT 3 in the form of a cursor mark according 
to the coordinate signal in the optical signal received by the optical 
signal receiving section 4. 
In this case, when the operator suitably moves the detecting section of the 
portable input apparatus 5 in the direction substantially parallel to the 
display surface of the CRT 3, or suitably changes the angle of the 
portable input apparatus 5 with respect to the display surface, the tilt 
angle .theta.x of the portable input apparatus 5 in the X-axis direction 
and the tilt angle .theta.y in the Y-axis direction may be changed 
occasionally, and the position of the cursor mark displayed on the display 
surface of the CRT 3 may be changed occasionally with changes of the tilt 
angles. 
FIG. 2 is a perspective view showing an example of a structure in which 
non-split type light receiving elements are mounted on a main substrate 
used in the portable input apparatus according to the first embodiment. 
As shown in FIG. 2, the main substrate 18 has a shape of a rectangle and 
various elements (no figure number is assigned) all of which are 
integrated circuits are mounted on the whole surface thereof. To both ends 
of one width side of the main substrate 18, two LEDs 14a and 14b are 
attached outwardly, and to the center of the same, a sensor 19 which holds 
the first detector light receiving element 6a, the second detector light 
receiving element 6b and the reference light receiving element 6c is 
attached outwardly. 
According to the first embodiment as described above, the first detector 
light receiving element 6a, the second detector light receiving element 6b 
and the reference light receiving element 6c, each being of a non-split 
type, are used as the light receiving element 6 of the portable input 
apparatus 5 side. This ensures an easy production of the light receiving 
element 6 as compared with the split type light receiving element and 
enables the commonly mass-produced light receiving element to be used. 
Further, it is not necessary to use additional mounting substrates when 
the light receiving element 6 is mounted on the main substrate 18 of the 
portable input apparatus side. Thus, the cost of manufacturing the light 
receiving element 6 and peripheral devices thereof can be reduced. 
In addition, according to the first embodiment, a large amount the base 
light is incident at all times in the reference light receiving element 6c 
arranged between the first and the second light receiving elements 6a and 
6b, and the current output Ic from the reference light receiving element 
is maximum. However, if the size of the light receiving surface of the 
reference light receiving element 6c is made smaller than each size of the 
light receiving surface of the first and second detector light receiving 
elements 6a and 6b, signal levels (Ia, Ic) become relatively high when the 
current outputs Ia and Ic of the first and second detector light receiving 
elements 6a and 6b are normalized to obtain current outputs Ia/Ic and 
Ib/Ic. Thus, excellent signal-to-noise ratio of the normalized current 
outputs Ia/Ic and Ib/Ic can be obtained, whereby stable normalized current 
outputs Ia/Ic and Ib/Ic can be obtained. At the same time, the difference 
between the normalized current outputs Ia/Ic and Ib/Ic of the first and 
second detector light receiving elements 6a and 6b becomes smaller, 
thereby obtaining accurate time shared output voltages without 
consideration of transient response caused when switching of the time 
shared output voltages. 
Furthermore, since each of the first and second detector light receiving 
elements 6a and 6c have large light receiving surfaces, the light 
receiving areas of the first and second detector light receiving elements 
6a and 6c are larger than the light receiving area of the reference light 
receiving element 6c even if the orientation of the portable input 
apparatus 5 is shifted to the periphery of a screen of the CRT 3. Thus, 
even if the light receiving areas of the first and second detector light 
receiving elements 6a and 6c are reduced due to the peripheral walls of 
the openings of the diaphragms thereof in the periphery of the screen of 
the CRT 3, a return phenomenon of the cursor mark on the screen can be 
prevented. 
FIG. 3 is a block diagram showing the second embodiment of the portable 
input apparatus according to the present invention which includes a 
relative angle detection apparatus together with a controllable 
information processing apparatus comprising a computer as in the case of 
the first embodiment. 
As shown in FIG. 3, the shielding member 6as of the first detector light 
receiving element 6a and the shielding member 6bs of the second detector 
light receiving element 6b are provided so as to shield substantially 
lateral half portions of the light receiving surfaces of the first and 
second detector light receiving elements 6a and 6b in the oblique and 
different directions to each other. At the same time, a shielding member 
6csof the reference light receiving element 6c is provided so as to shield 
a substantially longitudinal half portion of the reference light receiving 
element 6c. The first detector light receiving element 6a, the second 
detector light receiving element 6b and the reference detector light 
receiving element 6c are connected to inputs of an adder 15, and the 
outputs of the adder 15 are connected to the first division circuit 7a, 
the second division circuit 7b and the third I-V converter 8c, 
respectively. The first and second detector light receiving elements 6a 
and 6b are connected to inputs of the division circuit 16, respectively. 
The first detector light receiving element 6a, the second light receiving 
element 6b and the reference light receiving element 6c are connected to 
inputs of an adder-subtracter 17, respectively, and the output of the 
adder-subtracter 17 is connected to the second I-V converter 8b. 
The structure of the portable input apparatus of the second embodiment is 
different from that of the portable input apparatus of the first 
embodiment in the following points. The shape of the shielding member 6as 
of the first detector light receiving element 6a and the shape of the 
shielding member 6bs of the second detector light receiving element 6b are 
different from the shapes of the shielding members 6as and 6bs of the 
first embodiment; the shielding member 6cs is newly provided also on the 
reference light receiving element 6c of the second embodiment of the 
portable input apparatus for shielding a substantially lateral half 
portion of the light receiving surface thereof; and the adder 15, the 
subtracter 16 and the adder-subtracter 17 are newly provided in the 
portable input apparatus of the second embodiment. However, since there is 
no other structural difference between the portable input apparatuses of 
the first and second embodiments, the description of the extra structure 
will be omitted. 
The portable input apparatus of the second embodiment constructed as 
described above is operated as follows. In the second embodiment, however, 
the operation of the portable input apparatus after signal conversion 
section outputs the time shared output voltages is the same as that in the 
portable input apparatus of the first embodiment. Therefore, merely the 
operation before the signal conversion section outputs the time shared 
output voltages after the base light from the light emitting section 2 of 
the computer 1 is incident in each of the first detector light receiving 
element 6a, the second detector light receiving element 6b and the 
reference light receiving element 6c will be described, and description of 
the extra operation will be omitted. 
First, when the base light is incident in each of the first detector light 
receiving element 6a, the second detector light receiving element 6b and 
the reference light receiving element 6c, the current outputs Ia, Ib and 
Ic are output therefrom. These three current outputs Ia, Ib and Ic are 
supplied to the adder 15 and the adder-subtracter 17, respectively, and 
two current outputs Ia and Ib are supplied to the subtracter 16. The adder 
calculates three current outputs Ia, Ib and Ic and outputs addition 
current output (Ia+Ib+Ic). The subtracter 16 calculates two current 
outputs Ia and Ib and outputs subtraction current output (Ia-Ib). The 
adder-subtracter 17 adds two current outputs Ia and Ib and then, subtracts 
the current output Ic from the added value (Ia+Ib) to output 
addition-subtraction current output (Ia+Ib-Ic). 
Next, the first division circuit 7a receives and calculates the addition 
current output (Ia+Ib+Ic) and the subtraction current output (Ia-Ib) to 
output the first division current output (Ia-Ib)/(Ia+Ib+Ic). The second 
division circuit 7b receives and calculates the addition current output 
(Ia+Ib+Ic) and the addition-subtraction current output (Ia+Ib-Ic) to 
output the second division current output (Ia+Ib-Ic)/(Ia+Ib+Ic). At this 
time. The first I-V converter 8a receives and performs current-voltage 
conversion to output a light receiving output voltage V1 of the channel 1. 
The second I-V converter 8b receives and performs current-voltage 
conversion to output a light receiving output voltage V2 of the channel 2. 
The third I-V converter 8c receives the addition current output (Ia+Ib+Ic) 
and performs current-voltage conversion to output a light receiving output 
voltage V3 of the channel 3. 
The light receiving output voltages V1 to V3 are supplied to the selector 
switch 9. The movable contacts of the selector switch 9 are switched on a 
predetermined cycle by the switching controller 10, which operates in 
response to a channel switching signal supplied from the control section 
13, in order of channel 1, channel 2, channel 3, channel 1, channel 
2...(first switching mode) or switched in order of channel 1, channel 2, 
channel 1, channel 2...(second switching mode). In this case, the 
operation of the selector switch 9 for performing the switching operation 
either by the first switching mode or by the second switching mode is the 
same as that of the selector switch 9 in the above-described first 
embodiment. The light receiving output voltages V1 to V3, or the light 
receiving output voltages V1 to V2 are selected by the selector switch 9 
in a time sharing manner to become time shared output voltages, and the 
time shared output voltages are supplied to the signal processing section 
11. 
Various operations performed by the signal processing section 11 and the 
control section 13 are the same as the operations in the first embodiment. 
Therefore, the description thereof will be omitted. 
In the second embodiment, the first detector light receiving element 6a, 
the second detector light receiving element 6b and the reference light 
receiving element 6c, each being of a non-split type are also used as the 
light receiving element 6 of the portable input apparatus side. Thus, the 
light receiving element 6a can be manufactured with ease as compared with 
the split type light receiving element. Further, it is not necessary to 
use an additional mounting substrate even if the light receiving element 6 
is mounted on the main substrate 18 of the portable input apparatus 5 
side. Therefore, the cost of manufacturing the light receiving element 6 
and peripheral parts thereof can be reduced. 
According to the embodiments as described above, the controllable 
information processing apparatus 1 is a computer. However, the 
controllable information processing apparatus 1 is not limited thereto, 
and applicable to a game apparatus and an AV apparatus. 
As described above in detail, according to the present invention, the first 
detector light receiving element 6a, the second detector light receiving 
element 6b and the reference light receiving element 6c, each being of a 
non-split type, are used as the light receiving element 6 of the portable 
input apparatus 5 side. This offers the following advantages. The light 
receiving element 6 can be manufactured with ease as compared with the 
split type light receiving element. It is not necessary to use additional 
mounting substrates when the light receiving element 6 is mounted on the 
main substrate 18 of the portable input apparatus 5 side, whereby the cost 
of manufacturing the light receiving element 6 and peripheral devices 
thereof can be reduced. 
In addition, according to the present invention, when a lateral part of the 
light receiving surface of the first detector light receiving element 6a 
and a longitudinal part of the light receiving surface of the second 
detector light receiving element 6b are shielded and when the size of the 
light receiving surface of the reference light receiving element 6a is 
made smaller than each size of the light receiving surface of the first 
and second detector light receiving elements 6a and 6b, the signals become 
relatively high when the current outputs Ia and Ib of the first and second 
detector light receiving elements 6a and 6b are normalized to obtain 
normalized current outputs Ia/Ic and Ib/Ic. Therefore, excellent 
signal-to-noise ratio of the normalized current outputs Ia/Ic and Ib/Ic 
can be obtained, thereby obtaining stable normalized current outputs Ia/Ic 
and Ib/Ic. At the same time, the difference between the normalized current 
outputs Ia/Ic and Ib/Ic of the first and second detector light receiving 
elements 6a and 6b becomes smaller. This arrangement offers the following 
advantages. Accurate time shared output voltages can be obtained without 
consideration of transient response caused when switching of the time 
shared output voltages. A return phenomenon of the cursor mark on the 
periphery of the display screen can be prevented.