US3617761A

US3617761A - Radiation sensitive remote control system

Info

Publication number: US3617761A
Application number: US885010A
Authority: US
Inventors: Dexter P Cooper Jr
Original assignee: Bell and Howell Co
Current assignee: Bell and Howell Co
Priority date: 1969-12-15
Filing date: 1969-12-15
Publication date: 1971-11-02
Anticipated expiration: 1988-11-02

Abstract

A remote control system has a control for effecting a first control function in response to sensed incident light which has a first quality of polarization, and a second control function in response to sensed incident light which has a second quality of polarization. A projecting arrangement directs a beam of light away from polarized light-sensing means connected to the control, and a portable remote unit includes a reflector for directing the light beam to the sensing means, and light polarizers for selectively imparting on the light beam the mentioned first quality of polarization and alternatively the mentioned second quality of polarization.

Description

United States Patent [54] RADIATION SENSITIVE REMOTE CONTROL SYSTEM 20 Claims, 7 Drawing Figs. [52] US. Cl. 250/225, 250/216, 250/206 [51] Int. Cl G02f 1/18 [50] Field of Search 250/225, 83.3lR,2l6,206,203;356/114,116,117,118 [56] References Cited UNITED STATES PATENTS 2,140,368 12/1938 Lyle 250/225 CONTROL 2,167,484 7/1939 Berry 250/225x 2,362,832 11/1944 Land"... 2so 225x 2,651,771 9/1953 Palmer 2s0/225x 2,993,997 7/1961 McFarlane... 250/225x 3,158,675 11/1964 MurrayetaL. 356/116 3,502,888 3/1970 Stites 250/219 Primary Examiner-Walter Stolwein Attorney-Luc P.Benoit ABSTRACT: A remote control system has a control for effecting a first control function in response to sensed incident light which has a first quality of polarization, and a second control function in response to sensed incident light which has a second quality of polarization. A projecting arrangement directs a beam of light away from polarized light-sensing means connected to the control, and a portable remote unit includes a reflector for directing the light beam to the sensing means, and light polarizers for selectively imparting on the light beam the mentioned first quality of polarization and alternatively the mentioned second quality of polarization.

PATENTEDuuv 2 1971 3,617, 761

sum 1 OF 2 INVENTOR. v flfxrae P Coo/255k,

BACKGROUND OF THE INVENTION 1. Field of the Invention The subject invention relates to remote control systems and, more particularly, to control systems which are operated from a remote location through the agency of radiant energy.

2. Description of the Prior Art There exists a continuing need for remote control systems which dispense with the necessity of wires between the control signal receiver and the remote control unit.

Prior-art wireless remote control systems typically employ small radio transmitters, polarized, modulated or standard light sources or ultrasonic generators at the remote control unit. This raises one or more of the following disadvantages: necessity of power source or power outlet at the remote location, requirement of complex signal detection equipment at the control signal receiver, vulnerability to environmental interference, or generation of interference.

Background material for an improved remote control system may be found among signaling, communications, ranging and object identification systems that employ retrodirective reflectors at a remote location. However, a prior-art signaling system that employs a corner reflector which is selectively obscured by a shutter is directed to visual signaling and is thus not sufficiently developed for present purposes. Similar considerations apply to a prior-art voice communication system that employs -a corner reflector having a vibratile element for modulating a light beam with acoustical intelligence, and to prior-art ranging systems in which retrodirective reflectors with fixed 'or movable elements constitute the target to be located. A prior-art object identification system does use polarization phenomena to exclude spurious reflected signals, but relies on color codes to distinguish between different objects. This implies operation in the visible range of light, which is objectionable in those many applications in which the presence of a visible light beam is undesired.

SUMMARY or THE INVENTION The subject invention overcomes or materially alleviates these disadvantages by providing a remote control system comprising means for sensing incident light having a first quality of polarization and incident light having a second quality of polarization, control means connected to said sensing means for effecting said first control function in response to sensed incident light having a first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization, means for projecting a beam of light in a direction away from said control sensing means, and a portable remote unit. including means for reflecting said beam of light to said sensing means and means combined in said remote unit with said reflecting means for selectivelyimparting on said beam of light said first quality of polarization and alternatively said second quality of polarization.

Since the remote unit operates on a projected beam of light, no power source or outlet is required at the remote location. Control means which distinguish between qualities of light polarization may be of relatively simple design, including uncomplicated photocells and polarization filters. Vulnerability to environmental interference is inherently low in a polarized light system, since environmental light is typically depolarized. Systems which operate with directed light beams also are of low interference generation, and any annoyance by the light beam can be avoided by the use ofinfrared or other invisible radiation in accordance with a preferred embodiment of the invention.

From another aspect thereof, the invention resides in a remote control system comprising means for sensing incident light having a first quality of polarization and incident light having a second quality of polarization, control means connected to said sensing means for effecting a first control function in response to sensed incident light having said first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization, means for projecting in a direction away from said control means a beam of light polarized in a predetermined plane, and a portable remote unit including means for reflecting said polarized beam of light to said control means and means combined in said remote unit with said reflecting means for selectively realizing in said reflected beam of light said first quality of polarization and alternatively said second quality of polarization.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a frontal view of a first reflector device useful in the practice of the subject invention;

FIG. 2 is a frontal view of a second reflector device useful in the practice of the subject invention;

FIG. 3 is a diagrammatic view of a remote control system in accordance with-a preferred embodiment of the subject invention;

FIG. 4 illustrates a particular phase of operation of the system shown in FIG. 3;.

FIG. 5 is a perspective view of a remote control unit in accordance with a preferred embodiment of the invention;

FIG. 6 is a diagrammatic view of a modification of the control system of FIGS. 3 and 4, in accordance with a further preferred embodiment of the subject invention; and

FIG. 7 is a diagrammatic view of a further modification of the control system of FIGS. 3 and 4, in accordance with yet another preferred embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS FIGS. 1 and 2 depict retrodirective reflector devices that may be used in the practice of the subject invention.

More specifically, FIG. 1 illustrates a corner reflector 10 having three reflective surfaces l2, l3 and 14, each of which extends at right angles to the other two reflective surfaces. As is well known, a corner reflector is retrodirective in that it returnsincident beams of light to their origin. Corner reflectors may, for instance, be cast in glass or transparent organic materials or formed of highly reflecting aluminum, in accordance with conventional prior-art techniques.

FIG. 2 illustrates a retrodirective reflector 16 in which a layer of glass beads 17 is retained by an adhesive 18 on a matte white substrate 20. Arrangements of the type shown in FIG. 2 are of widespread use in motion picture and still projector screens, and in traffic signs and vehicle markings.

The particular use of the devices of FIGS. 1 and 2 will be explained as this description proceeds. At the present'juncture, the remote control system 23 shown in FIGS. 3 and 4 will be considered.

The system 23 comprises a base station 24, and a remote control unit 25. The remote control unit 25 may be of a handheld type. A lamp 27, with a reflector 28, is located at the base station 24 and projects a beam of light 30 away from the base station, and in particular away from a pair of

photocells

47 and 48.

The remote control unit 25 includes a housing 32 carrying a linear polarization filter 33 having its plane in the direction of the arrow 34, and a retrodirective reflector 35 which may, for instance, include a plurality of corner reflectors 10 of the type shown in FIG. 1, or a glass-bead reflector of the type illustrated in FIG. 2.

The light beam 30 entering the housing 32 is polarized by the filter 33 in the plane of the arrow 34. The polarized beam is reflected by the retrodirective reflector 35 through the filter 33 back to the base station 24 in the form of a reflected polarized beam 37. While it is not essential that the retrodirective reflector be nondepolarizing, for best efficiency it is desirable to have the reflector 35 not affect materially the plane or degree of polarization of the light incident upon it.

The beam 37 impinges on a pair of

linear polarization filters

40 and 41. If the device 35 were retrodirective in the strictest sense, the

filters

40 and 41 and lamp 27 would have to be located in the same spot, which would not be practical, or the use of an expensive Schmidt-type optical system would become necessary. An undesirably acute retrodirectivity is, however, easily avoided in practice by a less-than-perfect angular arrangement of the plates l2, l3 and 14 of the comer reflectors 10, or by a choice of glass beads 17 for the reflector 16 with a refraction index of 1.5 or less.

The

arrows

44 and 45 are intended to indicate that the filters 40 and 4] are arranged with their polarization planes at right angles to each other, so that the reflected beam 37 penetrates the filter 40, but cannot pass through the filter 41, when the remote unit 25 is heldgin such a position that the polarization planes of the

filters

33 and 40 are parallel to each other.

A photocell 47 is located behind the filter 40, and a photocell 48 is located behind the filter 41. Each of these photocells has a high dark resistance which is materially decreased by the impingement of light, as is conventional.

The

photocells

47 and 48 are connected in a control circuit 50 which includes a pair of transistors 51 and 52, base resistors 54 and 55, Zener diodes 7 and 58, relays 60 and 61 with

contacts

62 and 63, and a source 65 of electrical power, all connected as shown in FIG. 3.

The operation of the control circuit 50 may be described as follows:

The voltage of the source 65 is equally distributed among the series-connected

photocells

47 and 48 when both of these photocells are dark or are equally illuminated. The Zener diodes 57 and 58 are selected to have a breakdown voltage higher than one-half the voltage of the source 65 so that neither transistor 51 nor transistor 52 is rendered conductive as long as the voltage of the source 65 is equally distributed among the

photocells

47 and 48.

If the photocell 47 is illuminated, its resistance decreases rapidly and most of the voltage of the source 65 appears across the photocell 48 if the same is dark at that instant. The breakdown voltage of the Zener diode 57 is selected so that the emitter-collector circuit of v the PNP transistor 51 is rendered conductive when most of the voltage-of the source 65 appears across the photocell 48 as just described.

Conversely, the breakdown voltage of the Zener diode 58 is selected so that the emitter-collector circuit of the NPN- transistor 52 is rendered conductive when most of the voltage of the source 65 appears across the photocell 47, which is the case when the photocell 48 is illuminated while the photocell 47 is dark.

It will now be recognized that the base station 24 incorporates control means capable of effecting a first control function in response to incident light having a first quality of polarization (e.g. polarization in given plane), and a second control function in response to incident light having a second quality of polarization (e.g. polarization in a plane perpendicular to said given plane).

It is a principal feature of the preferred embodiment of the invention illustrated in FIGS. 3 and 4 that changes between the two control functions are easily effected by a positional change of the remote control unit 25.

This is illustrated with the aid of FIG. 4 which shows selected parts of the remote control system depicted in FIG. 3.

According to FIG. 4 the remotecontrol unit is rotated with respect to the position shown in FIG. 3 by an angle of 90 about an axis 70 which extends substantially along the light beam 30. In this manner, the plane of polarization of the filter 33 in the unit is displaced by 90 relative to the plane of polarization of the filter 40. In consequence the plane of polarization of the reflected beam 37 is rotated so that the beam 37 penetrates the filter 41 and illuminates the photocell 48, while the photocell 47 is now dark, since the beam 37 is now polarized at right angles to the plane of polarization of the filter 40.

It will now be appreciated that either the relay contact 62 or the relay contact 63 can be remotely closed, depending on the rotational position of the hand-held unit 25. More specifically, if the unit 25 is in the position shown in FIG. 3, then the transistor 51 is switched on for an energization of the relay 61 and a closure of the relay contact 63. Conversely, if the unit 25 is in the position shown in FIG. 4, then the transistor 52 is switched on for an energization of the relay 60 and a closure of the relay contact 62.

By way of example, it is assumed that the control system of FIGS. 3 and 4 is employed to control a motion picture projector 75 which projects luminous images from a film (not shown) with the aid of a lens system 76. It is further assumed that users of the projector 75 have the frequent desire to advance the film at a rapid rate for the skipping of scenes that are not to be displayed during a given performance. It is moreover assumed that users of the projector 75 have the frequent desire to run film backwards preparatory to a replay of given scenes.

From the mechanical point of view, these functions can easily be performed by means of adjustable gears which selectively decrease the gear ratio for a rapid film advance, and alternatively reverse the direction of the film drive. However, it is frequently desirable that these functions be controlled remotely by an operator who is seated in the audience at a location spaced from the projector.

According to FIG. 3, the

relay contacts

62 and 63 are connected to a control 78 that may have the requisite solenoids (not shown) for actuating the above-mentioned gears in the film drive. For instance, closure of the relay contact 63 may result in actuation of the fast forward film motion, while closure of the relay contact 62 may result in actuation of the film reversal mode.

Accordingly, if the remote control unit 25 is held in the rotational position shown in FIG. 3 and is then moved into the beam 30, the polarized reflected beam 37 will cause closure of the relay contact 63 and fast forward motion of the film in response to illumination of the photocell 47. If the fast forward motion is desired to be stopped, the unit 25 is simply moved out of the trajectory of the beam 30 whereupon normal film advance may resume.

Similarly, if the remote control unit 25 is held in the rotational position shown in FIG. 4 and is then moved into the beam 30, the polarized reflected beam 37 will cause closure of the relay contact 62 and reverse motion of the film in response to illumination of the photocell 48. This reverse film motion may thereupon be stopped by removal of the unit 25 from the trajectory of the beam 30.

It will now be recognized that the principles of the subject invention lead to a remote control unit that is inexpensive, very simple, and easy to actuate. If the unit is rectangular in cross section, having for instance a width greater than its height, it is particularly easy for the operator to memorize and bring about in the dark the particular position of the remote control unit 25 for the realization of a desired mode of operation.

This principle is illustrated in FIG. 5 in which a preferred form of remote control unit is shown in perspective.

According to FIG. 5, the housing 32 has a cross section extending through the axis of rotation 70 and having a greater dimension in one direction than in another direction at right angles to said one direction. By way of example, the housing 32 has a width 80 greater than its height 81. In this manner, the user of the remote control unit 25 will be able to know in the dark how he has to hold the unit for a desired effect. To aid his memory, markings or lettering 82 and 83 may be provided on the housing 32, such as an R" for film reversal, and an F F" for fast forward drive of the film.

If desired, the projector 75 may be used in lieu of the lamp 27 as a light source for the control system. In this case, the

photocells

47 and 48 are so arranged that the

filters

40 and 41 are illuminated by light reflected and polarized by the remote control unit 25 if this unit is held by its user into at least fringe areas of the beam 85 emitted by the projector 75. In this case, the control system can be operated with the visible light emitted by the projector.

'If visible light emitted by the lamp 27 is objectionable, invisible light may be used. By way of example, the lamp 27 maybe provided with an infrared filter 87 which renders the

beams

30 and 37 infrared and thus invisible, provided the lamp 27 is of a type that emits a component in the infrared region, as is the case with most incandescent lamps.

Various polarizers are suitable for the

filters

33, 40 and 41. Preferred for present purposes are sheet polarizers based on inventions by Dr. E. H. Land and sold by the Polaroid Corporation under its registered trademark Polaroid." Early types of these sheet polarizers included uniform dispersions of uniformly oriented acicular synthetic dichroic crystals,

' notably crystals of herapathite (quinine sulfate periodide), in

a matrix of cellulose acetate. Currently manufactured-sheet polarizers comprise the commercially available I-I-type, including oriented polyvinyl alcohol sheets imbibed with iodine, and the commercially-available K-type, including an oriented polyvinylene.

Polarizers suitable for infrared work include sheet polarizers manufactured with an increased iodine concentration on polyvinyl alcohol and with a heating of the polyvinyl alcohol matrix before stretching. ,The lamp filter 87 is then preferably selected to pass radiations in the near-infrared range, such as a range between visible red and about-2 microns.

FIG. 6 shows an important modification of the system of FIGS. 3 and 4, in accordance with a further preferred embodiment of the subject invention. Like reference numerals among FIGS. 3, 4 and 6 designate like or functionally equivalent parts. 1

According to FIG. 6, the retrodirective reflector 35 is mounted on a rotatable shaft 90 having a pinion 91 coupled thereto. A rack 92 engages the pinion 91 and is arranged and biased by a spring 93 so that the retrodirective reflector 35 has a rest position in which it extends at right angles to the polarizer filter 33. The reflector 35 carries a blind 95 which masks the reflector-35 against incident light when the same is in its illustrated rest position. this manner, no light is reflected by the reflector 35 until a button 96, which is mounted on the rack 92, is depressed so that the reflector 35 swings about the axis 90 in the direction of the arrow 98, until it extends parallel to the polarizer filter 33.

The light retrodirected by the reflector 35 when the same is located parallel to the filter 33 is again polarized by such filter 33, and the resultingpolarized beam 37 impinges on the

filters

40 and 41 of the

photocells

47 and 48. As before, the control 50 at the base station 24 causes closure of the contact 63 in response to illumination of the photocell 47 through the filter 40, and closure of the contact 62 in response to illumination of the photocell 48 through the filter 41.

The photocell 47 is illuminated when the remote control unit is in the position illustrated in FIG. 6 (note direction of arrow 34) and when the button 96 is depressed. Conversely, the photocell 48 is illuminated when the remote control unit is in the position illustrated in FIG. (note rotated position of arrow 34) and when the button 96 is depressed.

By way of example, it is assumed that the control system of FIG. 6 serves to selectively energize and deenergize an appliance and to select predetermined modes of operation of the appliance. For instance, the control system of FIG. 6 may be employed to control an on-off switch 100 and a channel selector 102 of a television set (not shown). To this end, the contact 62 is connected to a bistable" device, such as a flip-flop stage 103, which alternatively closes and opens the switch 100 in response to successive closures of the switch 62. The contact 63 is connected to a source 1050f electric power and to a stepping motor 106.

The stepping motor 106 has an armature 108 which incrementally drives a ratchet wheel 109 through a dog and pawl arrangement 110. The ratchet wheel 109 is coupled to the channel selector 102 for advancing the selector by one channel in response to an advancement of the ratchet wheel by one step.

The lamp 27 with reflector 28, and preferably with the infrared filter 87, may as shown in FIG. 3 and as explained above be located in the vicinity of the

photocells

47 and 48.

If it is desired to actuate the switch to its on position,

;the remote control unit 25 is held into the beam 30 in the rotational positions shown in FIG. 4, and the button 96 (see FIG. 6) is depressed so that the reflector 35 is swung into position for a reflection of the beam onto the

filters

40 and 41. The then prevailing polarization of the reflected 'beam 37 causes the photocell 48 to be illuminated. This in turn, closes the contact 62 so that the bistable circuit 103 is energized to turn the switch 100 to its on" position, in which position it remains after the button 96 has been released.

The remote control unit 25 is then rotated about the axis 70 to the position shown in FIG. 6. In that position the photocell 47 is illuminated through the filter 40 when the button 96 is depressed to swing the reflector 35 in the direction of the arrow 98. Illumination of the photocell 47 causes closure of the contact 63, which connects the source to the stepping motor 106. In consequence, the channel selector 102 is advanced by one channel. The button 96 in the remote unit 25 may then be released.

If desired, the button 96 may be depressed and released several times while the unit '25 is held in the beam 30as shown in FIG. 6. This results in a pulsing of the reflected and polarized beam 37 and in an advance of the channel selector 102 by as many channels as there are actuations ofthe button 96.

The switch is actuated to its off position by an insertion of the unit into the beam 30 in the rotational position 'shown in FIG. 4, and by a depression of the button 96.

Several modifications of the control system of FIG. 6 are apparent once its underlying principle has been understood. For instance, the reflector 35 could be mounted in the rear of the unit as shown in FIGS. 3 and 4, and a blind could be mounted on the pinion 91 so as to be in a vertical position obscuring the reflector when the button is in the illustrated released state, and to swing to a horizontal position permitting redirection of the beam 30 by the reflector when the button is depressed. In this case, the reflected and polarized beam 37 would be pulsed by movement of the blind relative to the reflector, rather than by movement of the reflector.

Moreover, a further selector and stepping motor combination similar to the selector 102 and stepping motor 106 could be connected to the contact 62 in substitution to the flip-flop 103 and on/off switch 100. This further selector and stepping motor combination could then, for instance, serve the selection of ultra-high frequency channels, while the selector 102 and stepping motor 106 could serve the selection of very-high frequency channels of a television set.

Yet another preferred embodiment of the invention is shown in FIG. 7 where like reference numerals as among FIGS. 3, 4 and 7 indicate like or functionally equivalent parts.

According to FIG. 7 the light beam 30 is polarized by a linear polarizer in a plane extending parallel to either the plane of polarization of the photocell filter 40 or the plane of polarization of the photocell filter 41. The filter 120 may be of the same material as the

filter

33, 40 or 41, and an infrared filter 87 may or may not be combined with the lamp 27 depending on whether operation with visible light or with invisible light is desired.

The remote control unit in FIG. 7 is equipped with phase retardation means in the form of a quarter-wave retardation plate 122 in lieu of the previously described linear polarizer 33. The linearly polarized beam 30 traverses the quarter-wave plate 122 twice; namely, once when entering the unit 25 and a second time after retrodirection by the reflector 35. In this manner, the plane polarized light of beam 30 is reflected with an effective retardation of one-half wavelength in beam 37. As a result, the plane of polarization of the beam 30 is rotated by 90 by the remote control unit 25 including the retrodirective reflector 35 and the quarter-wave retardation plate 122.

In this manner the reflected beam 37 may be made to illuminate the photocell which is associated with the polarizer whose plane of polarization extends at right angles to the plane of polarization of the polarizer120. By way of example, if the polarization plane of the lamp filter 120 extends parallel to the polarization plane of the photocell polarizer 40, then the reflected beam 37 will illuminate the photocell 48 behind the polarizer 41 upon direction and rctrodirection of light from the beam through the retardation plate 122.

Cessation of illumination of the photocell 48 by the beam 37 and illumination of the photocell 47 through the polarizer 40 by that beam may thereupon be brought about by removal of the retardation plate 122 from the path of the beam 30 and the path of reflected beam 37, at least for all practical purposes. By way of example, the retardation plate 122 may be mounted on a mechanism similar to that shown in FIG. 6 at 90, 91, 92, 93 and 96 so that the retardation plate may be swung to a position shown in FIG. 7 by dotted lines 125 upon actuation of a button. To this end, the plate 122 may for instance be so mounted on a shaft 90 that it extends vertically when a button 96 is released, and is swung horizontally as indicated at 125 when the button 96 is depressed.

In the latter case, the plane of polarization of the beam 30 is not rotated by the remote control unit, and the photocell 47 is illuminated through the polarizer 40.

Alternatively, the retardation plate" 122 may be retained in a vertical position and rotated by 4'5 so that the plane of polarization of the reflected beam 37 is rotated by 90 whereby the reflected beam 37 is caused to illuminate the photocell 47 through the polarizer 40.

Accordingly, the system of FIG. 7 again permits selective actuation of the

contacts

62 and 63, for the execution of distinct control functions, in response to distinct manipulations of the remote control unit 25. If desired, the principle illustrated in FIG. 6 may be employed in FIG. 7 to provide a system operating with pulsed reflected beams.

Quarter-wave retardation plates of the type used at 122 are well known in the light polarization art and are typically sheets of transparent anisotropic material, such as mica or stretched plastic film, displaying two different refractive indices producing in response to incident light two emerging rays having a phase difference of IT/2.

It will now be recognized that the system of FIG. 7 broadly represents an embodiment of the subject invention in which the

means

27 and 28 for projecting the light beam 30 have operatively associated therewith means 120 for polarizing the beam of light 30 in a predetermined plane, and in which the remote unit 25 includes means and 122 for selectively rotating the polarization of the light beam 30 in parallel to the plane of polarization of the filter and alternatively in parallel to the plane of polarization of the filter 41. i

I claim: 1. Remote control system comprising: means for sensing incident light having a first quality of polarization and incident light having a second, quality of polarization;

control means connected to said sensing means for effecting a first control function in response to sensed incident light having said first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization; means for projecting a beam of light in a direction away from said sensing means; and I a portable remote unit including means for reflecting said beam of light to said sensing means and means combined in said remote unit with said reflecting means for selectively imparting on said beam of light said first quality of polarization and alternatively said second quality of polarization.

2. Remote control system as claimed in claim 1, wherein:

said beam of light is a beam of invisible radiation.

3. Remote control system as claimed in claim 1, wherein:

said beam of light is a beam of infrared radiation.

4. Remote control system as claimed in claim 1, wherein:

said remote unit includes reflector means for said beam of light, and light polarization means combined with said reflector means and constructed to selectively impart on said beam of light said first quality of polarization and alternatively said second quality of polarization.

5. Remote control system as claimed in claim 1, wherein:

said projecting means are located adjacent said sensing means; and

said remote unit includes substantially retrodirective reflector means for said beam of light, and light polarization means combined with said reflector means and constructed to selectively impart on said beam of light said first quality of polarization an alternatively said second quality of polarization.

6. Remote control system as claimed in claim 5, wherein:

said beam of light is a beam of invisible radiation.

7. Remote control system as claimed in claim 5, wherein:

said beam of light is a beam of infrared radiation.

8. Remote control system as claimed in claim 1, wherein:

said sensing means include means for sensing incident light polarized in a first plane, and incident light polarized in a second plane;

said control means include means for effecting said first control function in response to sensed incident light polarized in said first plane, and said second control function in response to sensed incident light polarized in said second plane; and

said remote unit includes a combination of substantially retrodirective reflector means and light polarization means for selectively polarizing said beam of light in said first plane and for reflecting said beam of light polarized in said first plane to said control means for initiation of said first control function, and for alternatively polarizing said beam of light in said second plane and for reflecting said beam of light polarized in said second plane to said control means for initiation of said second control function.

9. Remote control system as claimed in claim 8, wherein:

said remote unit includes a portable housing containing said retrodirective reflector means, and said light polarization means include a linear polarization filter mounted in said housing for polarizing said beam of light in said first plane when said housing is held in at least one rotational position, and for polarizing said beam of light in said second plane when said housing is held in at least another rotational position displaced from said one rotational position by a predetermined angle.

10. Remote control system as claimed in claim 9, wherein:

said second plane is displaced from said first plane by an angle of and said predetermined angle of rotational position displacement is 90.

11. Remote control system as claimed in claim 10, wherein:

said housing has a first dimension in a first direction perpendicular to said beam of light, and a second dimension in a second direction perpendicular to said beam of light and to said first direction, with one of said first and second dimensions being greater than the other of said first and second dimensions to facilitate the orientation of said housing into any one of said rotational positions.

12. Remote control system as claimed in claim 10, wherein:

said housing has a width greater than its height to facilitate the orientation of said housing into angular positions displaced from each other by 90.

13. Remote control system as claimed in claim 1, wherein:

said first control function includes several first control operations, and said second control function includes several second control operations;

said control means are constructed to selectively effect said first control operations in response to sensed pulsed incident light having a first quality of polarization, and to selectively effect said second control operations in response to sensed pulsed incident light having a second quality of polarization;

said remote unit includes means for selectively pulsing said beam of light having said first quality of polarization and alternatively said second quality of polarization; and

said sensing means include means for sensing said pulsed beam of light having said first quality of polarization and alternatively said second quality of polarization.

147 Remote control system comprising:

means for sensing incident light having a first quality of polarization and incident light having a second quality of polarization; 1

control means connected to said sensing means for effecting a first control function in response to sensed incident light having said first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization;

means for projecting in a direction away from said sensing means a beam of light polarized in a predetermined plane;

and

a portable remote unit including means for reflecting said polarized beam of light to said control means and means combined in said remote unit with said reflecting means for selectively realizing in said reflected beam of light said first quality of polarization and alternatively said second quality of polarization.

15. Remote control system as claimed in claim 14, wherein:

said control means include means for effecting said first control function in response to sensed incident light polarized in a first plane, and said second control function in response to sensed incident light polarized in a second plane; and

said remote unit includes means for selectively reflecting said beam of light with a polarization in said first plane and alternatively reflecting said beam of light with a polarization in a second plane.

16. Remote control system as claimed in claim 15, wherein:

said projection means are constructed to polarize said projected beam of light in said first plane; and

said remote unit includes means for selectively rotating the polarization of said beam of light to said second plane.

17. Remote control system as claimed in claim 16, wherein:

said selective rotation means include phase retardation means.

18. Remote control system as claimed in claim 16, wherein:

said selective rotation means include a quarter-wave retardation plate.

19. Remote control system as claimed in claim 15, wherein:

said beam of light is a beam of invisible radiation.

20. Remote control system as claimed in claim 15, wherein:

said beam of light is a beam of infrared radiation.

Claims

1. Remote control system comprising: means for sensing incident light having a first quality of polarization and incident light having a second quality of polarization; control means connected to said sensing means for effecting a first control function in response to sensed incident light having said first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization; means for projecting a beam of light in a direction away from said sensing means; and a portable remote unit including means for reflecting said beam of light to said sensing means and means combined in said remote unit with said reflecting means for selectively imparting on said beam of light said first quality of polarization and alternatively said second quality of polarization.

2. Remote control system as claimed in claim 1, wherein: said beam of light is a beam of invisible radiation.

3. Remote control system as claimed in claim 1, wherein: said beam of light is a beam of infrared radiation.

4. Remote control system as claimed in claim 1, wherein: said remote unit includes reflector means for said beam of light, and light polarization means combined with said reflector means and constructed to selectively impart on said beam of light said first quality of polarization and alternatively said second quality of polarization.

5. Remote control system as claimed in claim 1, wherein: said projecting means are located adjacent said sensing means; and said remote unit includes substantially retrodirective reflector means for said beam of light, and light polarization means combined with said reflector means and constructed to selectively impart on said beam of light said first quality of polarization an alternatively said second quality of polarization.

6. Remote control system as claimed in claim 5, wherein: said beam of light is a beam of invisible radiation.

7. Remote control system as claimed in claim 5, wherein: said beam of light is a beam of infrared radiation.

8. Remote control system as claimed in claim 1, wherein: said sensing means include means for sensing incident light polarized in a first plane, and incident light polarized in a second plane; said control means include means for effecting said first control function in response to sensed incident light polarized in said first plane, and said second control function in response to sensed incident light polarized in said second plane; and said remote unit includes a combination of substantially retrodirective reflector means and light polarization means for selectively polarizing said beam of light in said fIrst plane and for reflecting said beam of light polarized in said first plane to said control means for initiation of said first control function, and for alternatively polarizing said beam of light in said second plane and for reflecting said beam of light polarized in said second plane to said control means for initiation of said second control function.

9. Remote control system as claimed in claim 8, wherein: said remote unit includes a portable housing containing said retrodirective reflector means, and said light polarization means include a linear polarization filter mounted in said housing for polarizing said beam of light in said first plane when said housing is held in at least one rotational position, and for polarizing said beam of light in said second plane when said housing is held in at least another rotational position displaced from said one rotational position by a predetermined angle.

10. Remote control system as claimed in claim 9, wherein: said second plane is displaced from said first plane by an angle of 90*, and said predetermined angle of rotational position displacement is 90*.

11. Remote control system as claimed in claim 10, wherein: said housing has a first dimension in a first direction perpendicular to said beam of light, and a second dimension in a second direction perpendicular to said beam of light and to said first direction, with one of said first and second dimensions being greater than the other of said first and second dimensions to facilitate the orientation of said housing into any one of said rotational positions.

12. Remote control system as claimed in claim 10, wherein: said housing has a width greater than its height to facilitate the orientation of said housing into angular positions displaced from each other by 90*.

13. Remote control system as claimed in claim 1, wherein: said first control function includes several first control operations, and said second control function includes several second control operations; said control means are constructed to selectively effect said first control operations in response to sensed pulsed incident light having a first quality of polarization, and to selectively effect said second control operations in response to sensed pulsed incident light having a second quality of polarization; said remote unit includes means for selectively pulsing said beam of light having said first quality of polarization and alternatively said second quality of polarization; and said sensing means include means for sensing said pulsed beam of light having said first quality of polarization and alternatively said second quality of polarization.

14. Remote control system comprising: means for sensing incident light having a first quality of polarization and incident light having a second quality of polarization; control means connected to said sensing means for effecting a first control function in response to sensed incident light having said first quality of polarization, and a second control function in response to sensed incident light having said second quality of polarization; means for projecting in a direction away from said sensing means a beam of light polarized in a predetermined plane; and a portable remote unit including means for reflecting said polarized beam of light to said control means and means combined in said remote unit with said reflecting means for selectively realizing in said reflected beam of light said first quality of polarization and alternatively said second quality of polarization.

15. Remote control system as claimed in claim 14, wherein: said sensing means include means for sensing incident light polarized in a first plane, and incident light polarized in a second plane; said control means include means for effecting said first control function in response to sensed incident light polarized in a first plane, and said second control function in response to sensed incident light polarized in a second plane; and said remote unit includes means for selectively reflecting said beam of light with a polarization in said first plane and alternatively reflecting said beam of light with a polarization in a second plane.

16. Remote control system as claimed in claim 15, wherein: said projection means are constructed to polarize said projected beam of light in said first plane; and said remote unit includes means for selectively rotating the polarization of said beam of light to said second plane.

17. Remote control system as claimed in claim 16, wherein: said selective rotation means include phase retardation means.

18. Remote control system as claimed in claim 16, wherein: said selective rotation means include a quarter-wave retardation plate.

19. Remote control system as claimed in claim 15, wherein: said beam of light is a beam of invisible radiation.

20. Remote control system as claimed in claim 15, wherein: said beam of light is a beam of infrared radiation.