System for optically transferring information between a moving object and a fixed position

An information transfer system for transferring information to a fixed position from a moving object. The information system includes a light beam scanning along the route of the moving object. The light beam is linearly deflected. The moving object is provided with a modulation-reflection apparatus which receives the linearly-deflected light and changes a rotary angle at a polarization surface based upon information from the moving object itself such as object number, destination, or running speed. This modulates the incident light and reflects it back in the direction from which it came. The reflected light from the modulation-reflection apparatus is received through a light-sensitive detection device which allows the light to pass corresponding to the rotary angle of the polarization surface. Consequently, information regarding the moving object is discriminated.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to an information transfer system for a moving 
object, which transfers the information between a predetermined spot and a 
moving object traveling on a route. 
(2) Description of the Prior Art 
A system has hitherto been well-known which provides a receiving station in 
the vicinity of an intersection and transfers information regarding a car 
from a transmitter provided thereat to the receiving station by use of 
radio waves so that the receiving station receives the radio waves to 
discriminate the present location of the car. Recently, optical 
communication has been put to practical use positively in various fields. 
Optical communication, when it is possible to use such to transfer the 
information to a fixed position from the moving object, such as the car, 
is very convenient, so that the present invention has proposed an 
information transfer system usable for the above described purpose. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide an information transfer system for 
a moving object, which is relatively simple in construction and capable of 
optically transferring the information between the predetermined spot and 
the moving object traveling on the route. 
Accordingly, the present invention is characterized in that a light beam 
scans along the route from the predetermined spot and is 
linearly-deflected; the moving object is provided with a 
modulation-reflection means which receives the linearly-deflected light 
beam and changes the rotary angle of its plane of polarization on the 
basis of information regarding the moving object, thereby modulating the 
incident light beam and reflecting it in the direction of the incident 
light beam; and the reflected light beam from the modulation and 
reflection means is received through a light-sensitive detection means 
which selectively allows the light beam to pass therethrough depending 
upon the rotary angle of its polarization plane, so that the information 
regarding the moving object is discriminated on the basis of the above 
described modulation and demodulation technique. 
These and other objects of the invention will be seen by reference to the 
description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a moving object 1, e.g., a car, runs on a road 2 of 
the route for the car 1, and a laser beam generating apparatus 3 is 
provided at a predetermined spot and at a predetermined height thereabove 
and allows a laser beam 4 having a sharp directivity to scan along the 
road 2. On the car 1 is provided a modulation-reflection means 5 which 
modulates the laser beam 4 in accordance with information regarding the 
car 1, the information including the car number, the destination or the 
running speed. A laser beam 6 is modulated with this information so as to 
be reflected toward the laser beam generating apparatus 3, which receives 
the modulated light beam 6 and discriminates the information as to the car 
1. 
The laser beam generating apparatus 3 of an embodiment of an information 
transfer system of the invention includes a laser beam scanning means for 
scanning the laser beam 6 along the road 2, a polarization means for 
plane-polarizing the laser beam 6, a light-sensitive-detection means 
selectively allowing the light beam to pass therethrough depending upon a 
rotary angle of the plane of polarization of the laser beam 6 returning 
from the car 1, a receiving means for receiving the laser beam having 
passed through the light-sensitive-detection means, and a discrimination 
means for discriminating a signal from the receiving means. 
In FIG. 2(a), reference numeral 31 designates a laser beam generator. A 
solar cell 32, utilized as the receiving means, as shown in FIG. 2(b), is 
provided at the front of laser beam generator 31, at the center of which 
is bored a bore 321 through which the laser beam 4 passes. 
In addition, the receiving means utilized is not confined to the solar 
cell, but may use a photodiode or a photo-transistor. 
The solar cell 32, as shown in FIG. 2(d), is provided at the front thereof 
with an analyzer 33 and at the position opposite to the bore 321 with a 
polarizer 34 as a polarizing means. 
On the other hand, a housing 35 shown in FIG. 2(a), has a bore 36, through 
which the laser beam 4 generated from the laser beam generator 31 passes, 
and accommodates a rotary mirror 38 mounted to a drive shaft of an 
electric motor 37 which rotates the mirror 38 to reflect the laser beam 4 
generated from the laser beam generator 31, the laser beam 4 scanning 
sequentially along the road 2. Thus, the laser beam scanning means 
includes the laser beam generating means 31 and rotary mirror 38 rotated 
by the motor 37. 
Referring to FIG. 3(a), reference numeral 51 designates an C-like-shaped 
iron core around which a coil 52 is wound. In a gap 53 of the core 51 is 
interposed a corner cube 54 formed of a Faraday effect element of lead 
glass and shaped as shown in FIG. 3(b). Hence, the laser beam 4 incident 
on the corner cube 54 is reflected thereby in the direction of the 
incident laser beam 4. While the incident laser beam 4 is being so 
reflected, the coil 52 would around the core 51 is supplied at both ends 
thereof with an information signal regarding the car 1 as, for example a 
pulse signal comprising a predetermined code. As a result, a current 
flowing in the coil 52 changes in correspondence with the pulse signal and 
subsequently a magnetic field generated in the coil 52 changes, whereby 
the plane of polarization of the laser beam 4 incident on the corner cube 
44 and plane-polarized therewith will be rotated by the Faraday effect 
thereon in correspondence with the pulse signal supplied to the coil 52. 
Hence, the laser beam 6 reflected from the corner cube 54 is 
polarization-modulated by the information signal regarding the car 1. 
In detail, the modulator-reflector 50, as shown in FIG. 4, is supplied, for 
example, with signals representing the car number, the destination 
information, and the speed information of the car 1, the car number signal 
being set by a car number setting unit 55, the destination information 
signal by a destination setting unit 56, and the car speed signal by a 
car-speed detector 57. Pulse signals representing the information from the 
car number setting unit 55, destination setting unit 56 and car speed 
setting unit 57, are applied to the modulator-reflector 50 through an OR 
gate 58, the modulator-reflector 50 modulating the laser beam 4 incident 
thereon on the basis of the information signals applied from the OR gate 
58. 
Next, referring to FIG. 5, the solar cell 32 utilized as the receiving 
means detects the laser beam 6 having passed through the analyzer 33 so 
that a signal detected by the solar cell 32 is amplified by an amplifier 
71 and applied to a demodulator 72, the demodulator 72 serving to 
demodulate the information signal of laser beam 6 and to discriminate the 
information regarding the car 1, the signal demodulated by the demodulator 
72 being applied to, for example, an indicator 73 which displays the car 
number, destination or car speed of car 1. 
Next, explanation will be given on a concrete operation of an embodiment of 
the information transfer system of the invention by reference to FIGS. 1 
through 5. Firstly, the laser beam 4 generated by the laser beam generator 
31 passes through the polarizer 34 and is plane-polarized to be incident 
on the rotary mirror 38 and is then sequentially scanned thereby along the 
road 2 on which the car 1 runs. As a result, the modulator-reflector 50 
loaded on the car 1 receive the laser beam 4 at a certain spot on the road 
2. While receiving the incident beam 4, the modulator-reflector 50 at the 
modulation-reflection means 5 is supplied information signals from any one 
of the car number setting unit 55, destination setting unit 56 and car 
speed setting unit 57, such as the pulse signal, through the OR gate 58. 
Therefore, the laser beam 4 incident on the corner cube 54 of the 
modulator-reflector 50 undergoes rotation of its polarization plane in 
correspondence with the applied pulse signal by means of the Faraday 
effect and is subjected to modulation, the laser beam 6 modulated in the 
corner cube 54 being reflected in the incident direction of laser beam 4 
and then reflected by the rotary mirror 38 to be incident on the analyzer 
33. Since the analyzer 33 allows only the incident light having a 
polarization plane of a predetermined angle to pass therethrough, when the 
analyzer 33 is set to pass therethrough only the light whose polarization 
plane is rotated due to modulation applied by the modulator-reflector 50, 
the laser beam passing through the analyzer 33 becomes an interrupted 
light beam corresponding to the pulse signal. Accordingly, the solar cell 
32, receiving the laser beam 6 having passed through the analyzer 33, 
outputs a signal corresponding to the pulse signal representing the 
information regarding the car 1, the signal being amplified by the 
amplifier 71 included in a receiving unit 7, and thereafter demodulated 
and discriminated into the predetermined pulse signal by the demodulator 
72 as the discrimination means, and thereby being applied to the indicator 
73. As a result, the indicator 73 displays the car number, destination, or 
car speed, of car 1. 
Alternatively, the laser beam for scanning may be a light beam of infrared 
rays, visible rays or others. 
As can be seen from the above description, the information transfer system 
for the moving object of the invention can transfer the information by 
light between the predetermined spot and the moving object on the road 
without providing the light-beam generating means at the moving object, 
thereby being very convenient for practical use. 
While an embodiment of the invention has been shown and described, the 
invention is not limited to the specific construction thereof, which is 
merely exemplary in the specification rather than confined thereto.