LENS FOR RECEIVING AND/OR TRANSMITTING INFRARED RADIATION

Abstract: Infrared lens for receiving and/or transmitting infrared radiation. The lens has such ray-refracting surfaces that radiation aimed at the lens through the refracting surfaces of the lens can be applied to a detector (200) located at the center axis of the lens in such a way that it is possible to use both the infrared rays coming from the hemisphere in front of the device and also the reflected rays, and that, in the middle of the lens. The lens comprises a curved refracting surface (120; 440; 592), and a second refracting surface (110; 420; 591) associated with the first surface, located at an angle ( alpha ) with respect to the center axis (X) of the first surface, so that infrared rays coming from the transmitting device can be aimed at the detector (20; 200) even when the direction of the center axis (X) of the lens deviates from the straight line between the transmitting device and the detector of the receiving device.

Description: Lens for receiving and/or transmitting infrared radiation, The invention relates to an infrared lens, an apparatus for using an infrared lens, and a use of an infrared lens. The use of a spherical lens for focussing infrared waves on a detector is known in the Prior Art. Also such spherical surfaces are known through which infrared rays are arranged to be sent from transmitting equipment. Such an infrared apparatus is known in which the transmitting unit is arranged to for instance transmit the sound of a television set so that said sound is amplitude- modulated and transmitted as amplitude-modulated infrared waves to a receiver, which- receives said amplitude-modulated signal with a detector, and in which receiver the signal received by said detector is frequency-modulated and reconverted to a sound signal of varying frequency. A hemispherical collector lens in front of the detector is used in said known apparatus. A specific drawback of this device is that the receiver, with headphones connected to it, is very sensitive to the right and straight orientation of the receiver lens with respect to the transmitting unit. If a person even slightly changes his or her perpendicular aim at the transmitting unit, the reception will grow essentially worse. Even small variations of orientation will make the reception unstable. The object of the invention is to provide such an infrared-radiation or infrared-wave refracting lens which is, from a hemisphere (a hemispherical space) , as effectively as possible able to collect infrared rays to a detector or an element meant to receive radi¬ ation. Such detector can be a light-sensitive sensor, which for instance receives amplitude-modulated sound signal and in which sensor said amplitude-modulated sound signal is specifically an infrared signal. A specific object of the invention is to provide such a lens and apparatus arrangement, which effectively collects infrared waves even when the orientation of the person changes with respect to the transmitter. An object of the invention is specifically to provide such a lens using and refracting infrared waves, in which, when the center axis of the lens is. essentially unparallel with the straight line between the receiver and the transmitter, said lens is able to receive direct transmitter rays even at large deflection angles and refract them to the detector. Another object of the invention is to provide such a lens arrange¬ ment which is economical to manufacture. Another object of the invention is to provide such an infrared apparatus making use of an infrared lens in accordance with the invention, which is able to operate on a wide frequency range, which needs little power, which is able to provide good sound reproduction, and which is able to receive infrared wave signal from the whole hemisphere, so that an apparatus in accordance with the invention is able to use both the reflected'rays and the direct rays coming from the transmitter, and direct waves even when the center axis of the" lens of the receiving apparatus is not directly aimed at the transmitting apparatus. Another object of the invention is such a use of an infrared lens in which the special features of an infrared lens in accordance with the invention can be exploited. Thus it is an object of the invention to provide such an apparatus which can be used in association with mobile radio telephones. It is also an object of the invention to provide such a device arrangement using an infrared lens in accordance with the invention which can be " used in simultaneous interpretation. Another object of the invention is such a use of an infrared lens in which an infrared lens in accordance with the invention is used in association with a wireless microphone. Still another object of the invention is such a use of an infrared ' lens in which a lens in accordance with the invention is used in association with an image recording device. The principal characteristic feature of the invention is that the lens has such ray-refracting surfaces that radiation aimed at the lens through the refracting surfaces of the lens can be applied to a detector located at the center axis of the lens in such a way that it is possible to use both the infrared rays coming from the hemisphere in front of the device and also the reflected rays, and that, in the middle of the lens, the lens comprises a curved re¬ fracting surface, and a second refracting surface associated with the first surface, located at an angle with respect to the center axis of the first surface, so that infrared rays coming from the transmitting device can be aimed at the detector even when the direction of the center axis of the lens deviates from the straight line between the transmitting device and the detector of the receiving device. The invention will now be described in detail with reference to some feasible embodiments illustrated in the figures of the accompanying drawing, with no intention to restrict the invention to these embodiments. Fig. 1 shows an axonometric view of the first feasible embodiment of a lens in accordance with the invention. Fig. 2 shows a cross-section view of the lens of Fig. 1; the figure also shows a separate detector for receiving infrared radiation. Fig. 3 shows an axonometric view of the second feasible embodiment of a lens refracting infrared radiation. Fig. 4 is a cross-section view of the same as Fig. 3. Fig 5A shows an axonometric view of the third separate embodiment of a lens in accordance with the invention. Fig. 5B shows the fourth embodiment of a lens in accordance with the invention. Fig. 5C shows the fifth embodiment of the lens. Fig. 6 shows an infrared apparatus in accordance with the invention, in which an infrared lens in accordance with the invention is used. The figure diagrammatically illustrates a so-called infravox device arrangement. Fig. 7 is an axonometric view of a device illustrated in Fig. 6. Fig. 8A and 8B are wiring diagrams of devices shown in Figs 6 and 7, ' which are so-called wireless listening devices. Fig. "8A is the wiring diagram of the transmitter unit.. Fig 8B is a wiring diagram of a wireless listening device corre¬ sponding to Fig. 6 and Fig. 7. In both Figs 8A and 8B the illus- trations are partially schematic. Fig. 9 is a diagrammatic illustration of the use of a lens in accordance with the invention in association with a mobile radio telephone. Fig. 10A illustrates the use of a lens in accordance with the invention in association with a wireless microphone. Fig. 10B illustrates the use of a lens in accordance with the invention in association of a wireless microphone used together with a music instrument. Fig. 11 illustrates the use of an infrared lens in accordance with the invention in association with an image recording device, and s shown in the figure, in association with a video camera. Fig. 12 illustrates the use of an infrared lens in accordance with the invention in association with a simultaneous interpretation device intended for congress facilities and similar. Fig. 13 illustrates the use of an infrared lens in association with studio equipment partially intended for aurally handicapped persons. Fig. 14A shows reference graphs of ranges and angles. The continuous line shows a reference alternative in which the receiver detector was without any lens. The dashed line shows a reference alternative with a conical lens, and the dotted-dashed line shows a reference alternative with a conical prism lens. Fig. 14B is the sound reproduction curve of an intravox device. Fig. 1 is an axonometric view of an embodiment of an infrared lens in accordance with the invention. Fig. 2 shows the embodiment of Fig. 1 as a cross-section view and in a larger scale. It is possible to attain very high optical qualities with a lens in accordance with the invention. In accordance with the invention, it has been possible to provide such a lens solution which can receive both radiation coming directly from a radiation source and reflected radiation. A lens in accordance with the invention is able to refract said direct rays to the detector both when the center axis of the lens is essentially directed toward the radiation source and also when the center axis X of the lens is essentially deflected from the position toward the radiation source. The intention has been, in accordance with the invention, to provide such a lens solution for collecting infrared radiation in which a lens in accordance with the invention receives said directly oncoming rays when the direction of the center axis X of the infrared lens devi¬ ates from the straight line between the radiation source and the receiver as much as 90°. In the first embodiment of a lens in accordance with the invention, we have embodied such a lens solution in which the prism effect of the edge areas of the lens has been made use of. The rays indicated by arrow L j _ are refracted to the central area of the lens, and from the central convex lens surface further on to the receiving detector or similar. The rays coming exactly perpendicularly against the side surfaces are, in the embodiment of Fig. 1, as indicated by L£, reflected from the conical surface directly to the detector, or, as indicated by L3, directly to the detector 200. In a lens solution in accordance with the invention the area of the useful refracting surface is many times larger than for instance in such a lens solution in which there is, in the middle of the lens, only a conical surface or/and a truncated cone surface without arranging a separate, curved, feasibly convex refracting surface at the end of the conical surface when using only a conical surface located in the middle of the lens, a drawback is that the rays hit and are refracted poorly to the detector particularly when the center axis of the lens cannot be aimed towards the transmitter. It is said that in this case the direct rays have a so-called shading effect. In the first embodiment shown in the figure the lens provides a • wide reception angle. There are two main reasons for a wideness of the reception angle. With a lens in accordance with the invention as illustrated in Figs 1 and 2, a so-called prism effect is created in the edge areas of the lens. The rays L ] _ are guided accurately to the detector surface L. Secondly, a lens in accordance with the invention reflects rays L2 to the detector from the conical surface.- Said conical surfaces reflect the rays exactly to the detector which is arranged symmetrically with respect to the center axis X. Also the rays L3 coming essentially perpendicularly to the side surfaces are refracted exactly on the detector. The detector, with which we here mean a light-sensitive component receiving infrared rays is arranged on the flat surface of an infrared lens in accord¬ ance with the invention. Said detector is tightly and feasibly installed on said flat surface by glueing or with some other fixing method. The long range of particularly the conical lens in accord¬ ance with the embodiment 1 is based on the magnifying effect of the lens, the so-called magnifying-glass effect, which is not disturbed by the correctly angled walls of the cone. In accordance with the invention, in the first embodiment the lens comprises the first curved and light-refracting surface which is feasibly a convex surface and feasibly a spherical zone surface 100. In accordance with the invention, in this embodiment a trunc- ated cone surface 110 is connected to said spherical zone surface 100, whose radius of curvature is R y is preferably approx. 10 mm. Said conical surface 110 is connected at 101 to the curved first surface 100. The truncated cone surface 110 is preferably a surface of a circular cone, preferably a straight circular cone surface, and to it such a second convex and/or curved centrally-located refracting surface 120 is connected, which is preferably a spherical surface. Said first curved refracting surface should preferably be a spheri- cal zone surface with a radius R v of approx. 10 mm, and said second curved refracting zone should also preferably be s spherical zone surface with a radius R^. of approx. 7 mm. The angle between the side line 111 of the conical refracting surface 110 and the central axis of the ' lens X is preferably 45- 70°. Even more preferably said angle is 50-65° and most preferably the angle a is approx. 57°. Said side angle is in the figure- indicated by α. The most feasible distance of the detector from the center K of the second curved refracting surface 120 is 5 mm. The detector, which is indicated by 200, is fitted centrally with respect to the central axis X of the lens. In another embodiment of the invention, the detector 200 can be replaced with a device transmitting infrared light, feasibly a diode or similar transmitting infrared light. Thus a lens in accordance with the invention can, besides as an infrared-light collector, also be used for sending infrared radiation as an infra¬ red-radiation diverging lens. The curvature center D of the curved refracting surfaces 100 and 120 is preferably located at a distance of 7 mm from the center K of the top level Y of the lens, which K, in the embodiment of the figure, is also the apex of the segment 1 of the second refracting curved surface 120. In the illustrated lens embodiment there is an air space A between the second refracting curved surface 120 and the conical surface 5 110. At its best, the circular diameter of the flat surface E on the detector 200 side of the lens is 19,2 mm. An embodiment in accordance with the invention also comprises a protruding part 220. The protruding part 220 protrudes from the surface E. The protruding part 220 functions as a fastening bracket, and its 10 cross section is also preferably circular, its diameter 3 being preferably 13,8 mm. F indicates the detector-side surface plane of the protrusion 220. A lens in accordance with the invention refracts rays l * ι, l _ and " 15 L3, coming to the lens from the side, to the detector. The ray L_ goes in the edge area of the plane. Said ray is refracted from the first curved surface 100 to the conical surface 110 and further on to the second central curved surface 120, and further on to the detector 200. Similarly, the ray L2 comes almost perpendicularly 20 with respect to the central axis X. Said ray is refracted at the first curved surface 100 to the conical surface 110, and from there it is reflected directly to the detector 200. The ray L3 is refracted directly from the curved surface 100 to the detector. 25 The length g of the protrusion 220 in accordance with the invention ' is preferably 0,6 mm. At the plane Y, the diameter of the bottom circle ^ of the conical surface 110 is preferably 14,1 mm. The circular diameter $2 °f t ^ lβ enα - at t ^ ιe side of the flat surface E of the conical surface 110 is preferably 9,3 mm. 30 When using a lens in accordance with the invention, for instance the stereo effect in sound reproduction will be very good. When using infrared radiation, for instance the room acoustics can be made use of. The so-called reverberation is experienced as stereo 35 effect. For instance the rays reflected from the walls of the room are somewhat late compared with the direct radiation. When using a lens in accordance with the invention, both the direct and the reflected rays can be used; it is also possible for the person carrying the receiver to turn as much as 90° to either direction from the straight line between the transmitter and the receiver without any detrimental influence on the receiving ability. With a device in accordance with the invention also reflected radiation can be made use of so that it is possible to turn as much as 180° away from the transmitter. Figs 3 and 4 illustrate another feasible embodiment of a lens in accordance with the invention. In this embodiment there is a conical hollow in the center part of the lens. In this embodiment, the lens again comprises a curved and/or convex side surface 300 which is preferably a spherical surface and/or a spherical-zone surface, and a circular revolution surface. The curvature radius R D of said surface is preferably 10-20 mm. Said surface 300 functions as a surface which refracts light-rays L ] _' ,L ] _" coming-from the side. After hitting the curved lens surface 300, the light rays L^' are " refracted directly to the detector. In the middle of the lens there is another refracting surface being preferably a conical surface and most preferably a circular cone surface. In the embodi¬ ment of the figure, said conical surface 310 is a full cone surface, but in an embodiment not separately illustrated the surface 310 is a truncated cone surface. The light rays 1,-t " are refracted from the surface 300 to the conical surface and from there they are refracted to the detector. Within the cone there is an air space A. In said embodiment the lens does not have a so-called prism effect with respect to the radiation coming from the side. Even an infrared lens in accordance with the embodiment of Fig. 2 is con- siderably more advantageous than spherical lenses or a receiver detector without any collector lens. Also in this embodiment the detector 200 is fastened to the flat surface 320 of the lens. The cone angle α is preferably between 45-70°, and most preferably α - 57°. Fig. 5A illustrates the third feasible embodiment of an infrared lens in accordance with the invention. The illustrated embodiment is intended for such applications in which the purpose is to receive infrared radiation transmitted by an infrared transmitter at a very narrow sector. Said solution is particularly suitable for such a lens use in accordance with the invention, in which the lens is particularly used for transmitting infrared radiation and for aiming them at a certain sector. This third embodiment of a lens in accordance with the invention comprises the first refracting curved lens surface 400 being preferably a section of a spherical surface, i.e. a zone surface of a sphere. To said first curved lens surface 400 and the light-refracting surface are connected other straight and flat refracting lens surfaces 420 and 421 located in the middle of the ^ lens at both sides of the symmetry axis x. As illustrated, said straight sections are connected to a second curved and/or convex refracting lens surface 440, whose cross- section is also preferably a circular surface. Fig. 5B shows such an embodiment in which the lens comprises the first refracting surface being preferably a curved surface and being preferably a spherical surface 450, and in which the second refracting surface is composed of straight surface sections 460 and 470, whereat there will be a triangular groove 480 in the middle of the lens. The lenses in accordance with the invention effectively collect both the direct radiation and the reflected radiation coming from the hemisphere. As the lens is able to use all rays coming from the whole hemisphere, it will also work with mere reflected rays. Therefore a lens in accordance with the invention is able to effectively receive infrared radiation also in cases where the direct connection between the transmitter and the receiver is prevented. In this case reflected rays come to help and the receiver will go on receiving transmitted modulated infrared signal. The lenses in accordance with the invention will work on a very wide sector; therefore they are able to receive transmitted signal also at an oblique angle with respect to the transmitter without the signal power being reduced. A lens in accordance with the invention is preferably manufactured of plastic material. Preferably it is made of acrylic plastic, "polymetylacrylate". In accordance with the invention, material well pervious to infrared radiation is used. Then the material is specifically tinted plastic. The lenses in accordance with the invention are particularly well suited for sound transmission applications based on infrared tech¬ nology. With a lens in accordance with the invention it is possible to use infrared radiation coming from the whole hemisphere. In accordance with the invention, it has been possible to carry out a lens-detector combination with which a person may turn as much as 90° with respect to the transmitter without any detrimental influ¬ ence on the sound transmission. Infrared radiation can.be received with a lens in accordance with the invention even when there is an obstacle between the infrared transmitter and the receiver and only for rays that are reflected for instance from walls can be used. Besides for receiving and collecting infrared radiation, the lenses in accordance with the invention can also be used for trans¬ mitting infrared radiation. Fig. 5C illustrates the fifth feasible embodiment of the invention. This embodiment is particularly well suited for receiving sound in association with video tape recording equipment. The embodiment of Fig. 5C is a cross-section view of a lens symmetrical with respect to the center axis X. A lens in accordance with the invention comprises the first refracting straight surface 590, and within the lens there is a conical surface 591 and, connected with it, a spherical surface or a curved refracting central lens section 592. The arrow S ] _ indicates that the detector 200 can be moved to different positions. Thus an adjustable lens in accordance with the invention can be used for instance for receiving sound from a certain distance. By means of the detector moving device 593, the detector 200 can, as indicated by arrow S^, be moved to a desired ' position with respect to the lens. In the figure letters f j _ and show two different positions of the detector. Fig. 6 shows a wireless listening device in accordance with the invention, based on the use of a modulated infrared carrier wave. Fig. 6 schematically illustrates an equipment arrangement in accordance with the invention. A radio-frequency signal from a TV " set, a radio device or similar is transferred to an infrared trans- mitter 510. ' The signal is amplitude-modulated and transmitted via transmitting diodes (preferably 1 to 200 diodes) into for instance a room. A receiver 520 located in the room receives the amplitude- modulated infrared-frequency signal. In the receiver 520 there is a lens receiving and collecting infrared radiation, in accordance with the invention. After frequency-modulation, the receiver 520 transfers the received signal into an audible and comprehensible form to be heard by the listener by for instance headphones. In Fig. 6, the headphones are indicated by 522. From the receiver 520, the received and frequency-modulated signal may be further 0 transmitted to a radiation loop 530, from which said- received signal can be transmitted to the hearing device wirelessly for instance with electromagnetic radiation. In Fig. 6, the hearing device is indicated by 550. Fig. 7 is an axonometric illustration of the described equipment arrangement. 5 A sound signal is transferred to transmitters 510 from for instance a radio device, and said radio-frequency signal is amplitude- modulated and transmitted by transmitting diodes 511 to the room. . As shown in Fig. 7, the transmitting device may be equipped with a 0 battery 513, the battery charging cable being indicated by 512. The transmitting device may also comprise a mains connection 514. The signal S^Q transmitted by the infrared transmitter 510 is received by receiving equipment 520. The infrared rays S^Q are received to the receiving device 520 by a lens 521, in accordance 5 with the invention. The signal, after being treated, for instance frequency-modulated, in the receiving device 520, is transmitted to headphones 522. The transmitter device 520 preferably comprises a volume adjustment knob 522, a battery charging switch 524, a rechargeable mini-size battery 525, and a carrying strap 526, by which the receiver 520 may be hung on the shoulder of a person. Fig. 8A illustrates a so-called infravox equipment arrangement or a wireless hearing device in accordance with the invention. It is particularly well suited for aurally handicapped, but also for those with completely normal hearing for receiving sound from a TV or a radio set, a cassette recorder or similar. Fig. 8A is a wiring diagram of the receiver device 520 for receiving amplitude-modulated infrared carrier wave. A receiving detector or a similar device installed in connection with a. lens in accordance with the invention receives the signal coming from the surroundings. In the diagram, 200 indicates the detector. The receiver 520 in accordance with the invention comprises a preamplifier circuit 1. The receiver 520 also comprises a modulation circuit 2, which frequency-modulates the signal received by the receiver 520. In the figure, arrow 3 indicates a rectifying circuit. From the pre¬ amplifier circuit 1 the signal is fed through a current circuit 6 into a modulation circuit 2, which frequency-modulates the signal. From the modulation circuit 2 the signal is transferred through a circuit 4 and 5 to the rectifying circuit 3. The low-frequency- voltage is regulated by branch 7. Said low-frequency-voltage regulating-circuit is indicated by 7. The sound signal is adjusted both in the current circuit 4 and in its continuation, the current circuit 5. A voltage is fed to the current circuit. Ref.number 8 indicates the power source. Ref.number 9 indicates the power switch. The voltage is fed through the switch 9. The direct voltage is directed through circuit 10 into the rectified circuit 3. The final sound signal is directed from the rectified circuit to the headphone jack 11. The voltage level coming from the power source 8 is adjusted in the power circuits 11 and 12, which are connected to the power source via a brancing point 13 and connecting circuits 14 and 15. The voltage is fed to the modulation circuit via a brancing point 17 and a connecting circuit 16. Therefore, in accordance with the invention, the amplitude-modulated signal is brought through an infrared lens to the detector, where- from the signal is taken to the preamplifier circuit and further on to the frequency- odulation circuit, from where the signal is, through the rectifying unit, taken to headphones for instance. Fig. 8B again illustrates a transmitting device 510 in accordance with the invention. Said transmitting device 510 modulates sound signal. Said modulated signal is then applied to transmitting equipment which are preferably transmitting diodes, which transmit said modulated signal further on to be received by a receiving device 520 or similar. In Fig. 8B, the ref.nos. 20 to 25 indicate transmitting diodes. Ref.no. 26 indicates the modulation circuit. An electrical sound signal produced by for instance a microphone is converted to a rectified signal in the rectifier 27. Current and voltage are fed from a battery 29 or similar, and the signal is applied to a modulation circuit 26 through a switch 28. The so- called modulation locking is made in the circuit 30. The modulated & signal is taken further through a circuit 31 to the branch 32 and further on to transmitting equipment 20 and 25, which are trans¬ mitting diodes, the number of which in this embodiment is six. An indicator.light 33 showing the position of the switch 28 is referred to by 33. When signal is applied to the modulation circuit 26 through a switch 28, the indicator light 33 is on. Fig. 9 is an illustration of a car-vox system or a-mobile radio telephone system in accordance with the invention, in which an infrared lens in accordance with the invention is used. The figure schematically shows the functional units used in an infrared lens system in accordance with the invention. In accordance with the invention, the sound signal is transmitted to the mobile telephone with a wireless microphone instead of a telephone handset. The person puts a so-called microphone transmitter unit for instance in the pocket of his coat or fastens it to his tie or coat lapel. Said unit comprises a so-called automatic voice-activated microphone 1001, which is switched on by voice. When the person speaks, the microphone is switched on and transmits signal SJ_Q to the trans¬ mitter unit of said unit 1000. The signal transmitted by said microphone is modulated in the modulating unit of the transmitter 1000, and said signal is wirelessly transmitted through a lens 20 in accordance with the invention to the receiver unit of the mobile telephone, in which the transmitted signal is received by reception diodes 1003 of the receiver unit. Said received signal is further modulated by frequency-modulation so that it can be further con¬ verted to an electrical signal to be in the normal way wirelessly transmitted from the telephone unit, or said voice signal can be transferred for instance to a cassette recorder 1007, to which also the voice signal received by the mobile radio telephone can be recorded. The microphone transmitter unit 1000 comprises a microphone, ' preferably a voice-activated microphone, which is switched on by voice. The transmitter unit 1000 feasibly. comprises a fastening surface or a fastening component 1002, with which the transmitter unit is fastened for instance to the tie or coat lapel. From the transmitter unit the modulated signal is transmitted through a lens 20 in accordance with the invention to the receiver unit of the telephone, in which the reception diodes 1003 receive the voice carrier signal S^g. In Fig. 9, the microphone transmitter unit 1000 is shown by dashed lines, being charged and stored in association with the receiver unit of the telephone. The received signal can be further modulated for instance with frequency- modulation in said receiving unit, and said signal can be taken by circuit 1004 to the actual mobile radio telephone 1005. From the telephone unit said voice signal can be taken further on for instance to a cassette recorder 1007 by circuit 1006. Said answering signal received by the mobile radio telephone can be moved by line 1008 to a loudspeaker 1009. The lens of the transmitting unit 1000 of the mobile radio telephone should preferably be the lens embodi¬ ment illustrated in Figs 5A and 5B, in which embodiment the signal being transmitted can be aimed along a certain channel to the receiver diodes 1003. In accordance with the " invention, it has been possible to fully exploit a lens arrangement in accordance with the invention. Par¬ ticularly the lens design illustrated in Figs 5A and 5B is speci¬ fically suitable for use in radio telephones. This is because in mobile radio use the distance between the person and the telephone is relatively short; in mobile radio use also the angle between the telephone and the radio is almost constant; therefore it can be assumed that the signals are transmitted from the transmitter to the receiver along a certain path, and a lens designed in accordance with the invention (lenses in Figs 5A and 5B) is speci¬ fically suitable for receiving and transmitting signals being transmitted along a certain path and for transmitting then along a certain path. Fig. 10A illustrates another lens use according to the-invention, in which a lens in accordance with the invention is used in associ- ation with a microphone 1010. In accordance with the invention, the microphone comprises transmitter diodes ^,A2,A3,A4 and A5 located in five separate sectors. For each transmission diode, the receiver unit also feasibly comprises for each transmitter diode a receiver of its own A^' ,A]_^;A2' .A2", ... ,A5', 5"). The voice signal transmitted by each transmitter diode depends on the position of the person. Similarly the position of the person with respect to the microphone is immediately noticed in the receiver; therefore the stereo effect is enhanced. Through for instance five transmitter diodes ( ^, 2, 3,A4,A5) the transmitter transmits a modulated voice signal, received by receiver units 2001,2002, arranged on different sides of for instance a stage. Each receiver is equipped with a voice signal latch, in other words the amplifiers are switched automatically off when the transmitted signal does not reach the receiver. The receiver detectors in the receiver 2001 are indicated by A^' ,A2' .A3' ^4' and A5' . Similarly the receiver detectors of the receiver 2002 are indicated by A j _",A2",A3" ,A " and A5". From the receivers the voice is applied to a universal amplifier 2010 and through it to loud¬ speakers 2011 and 2012. Fig. 10B illustrates a wireless microphone in association with a musical instrument. An example is a guitar. Each six strings have their own microphones. There are 1-n groups of six microphones. Now by connecting different microphone groups to action during play, and by changing said connected microphone with each other, such an effect is created which can be compared to variations of the tone colors or registers of for instance an organ or an accordion. Sounds produced-by different microphone groups are taken by leads 4001 or similar to a transmitter unit 4002 installed at the end of the fingerboard of the guitar. In accordance with the invention, the transmitter unit comprises five conical prism lens.es 4003,4004-, 4005,4006 and 4007. Each conical prism lens functions at a different frequency. They transmit signal which is amplitude-modulated to different frequencies. A receiver group working on different frequencies is connected to the amplifier of the instrument, whereat a detector 4011,4012,4013,4014,4015 of each receiver unit with its own frequency-modulation circuit receiving the frequency in question corresponds with each transmitting frequency and transmitting diode of the transmitter. From said receiving group and receiving device the signals are taken to be amplified in an amplifier unit and further on to be reproduced by for instance loudspeakers. The figure illustrates a guitar application, but it is obvious that this kind of use and corresponding equipment arrangement in accord¬ ance with the invention can be applied to any music instrument. The sound signals produced by microphone groups come by the micro¬ phone lead 4001. They are transferred to the transmitting unit 4002 installed at the end of the fingerboard of the guitar. As illustrated in the figure, the transmitting unit 4002 is equipped with five transmitting eyes 4003,4004,4005,4006,4007. Said trans¬ mitting eyes are feasibly five conical prism lenses, each of which are arranged to operate on a different frequency. They transmit signals which are amplitude-modulated to different transmitting frequencies. The receiver 4010 works at five different frequencies and receives signal S3 Q . The signal is modulated and transferred to an amplifying device 4020 through signal path 4016 and further on loudspeakers 4012,4022. Fig. 11 illustrates such a use of the invention in which a lens in accordance with the invention is used in association with an image recording device 3000, for instance a video recorder. The image recording unit 3000 comprises a receiver unit for receiving modu¬ lated carrier wave, and said signal S20 ϊ- s received through a receiving lens 3002 located for instance in a video camera 3000 or similar. A lens in accordance with the invention has feasibly been installed for instance at the top " of a telescope antenna 3001. The lens 3002 in accordance with the invention is so designed that it receives and collects the transmitted waves S20 rom a certain and desired distance, which can be adjusted by adjusting the distance between the detector and the lens by means of a screw device (593, Fig. 5G) or similar. The transmitting unit, which transmits the modulated infrared carrier wave, may be located for instance on a sports field. A device in accordance with the invention is very well suited for transmitting interviews in athletic contests directly to the studio or to the camera or similar. Thus it is possible to easily transmit a modulated voice signal past large audiences to be further transmitted by means of for instance radio methods. The transmitter 3004 produces a carrier wave S20. which is received to the image recording device 3000 by the lens 3002 of its telescope antenna 3001. The lens is preferably of the type shown in Fig. 5C. Fig. 12 is a schematic illustration of the use of a lens in accord¬ ance with the invention in association with simultaneous interpret- ation devices intended particularly for congress rooms or similar. The object of the invention is also a corresponding simultaneous ' interpretation device. Fig. 12 schematically illustrates a simul¬ taneous interpretation device in accordance with the invention. This simultan-vox device comprises, at least in the receiving equipment, lenses in accordance with the invention. The simultaneous interpreters transmit, each with their own languages and on their frequencies, the interpretation of the congress conversation. The speech captured by the microphones of the simultaneous interpreters is modulated and transmitted by high-power transmitters into the congress room. Said high-power transmitter may comprise one large disk unit, to which the transmitter diodes are fastened. Each frequency, in other words each language, may have its own trans¬ mitter diode group. When the persons enter the congress room, they may select a receiver unit according o the desired language in the lobby or similar. Each language has a receiver unit receiving its own frequency, which receiver unit comprises an infrared lens in accordance with the invention. In accordance with the invention, the table or similar containing the transmitter diodes can be fastened on the wall of the congress room, or said transmitter diode assembly may be suspended higher on top of a separate movable stand. Fig. 13 illustrates another lens use in accordance with the in¬ vention. This is a so-called studia-vox equipment and use arrange¬ ment, in which the teacher can by his own transmitter device aim the carrier wave of a certain frequency. Thus the teacher is able to direct his speech to certain students by selecting a certain carrier wave frequency at his transmitter. The student, to whom he wants to speak, has a receiving device working on the same carrier wave frequency. Speech transmitted by the student may also be transmitted through the same transmitter-receiver device and the corresponding lens, with which the teacher's speech is received, and this transmitted signal can, through the receiver device in the teacher's desk, after treatment, be directly transferred to a loudspeaker. Fig. 14A is a graphic comparison between different lens types and the situation when there is no lens in front of the detector. In the figure, the vertical axis shows the range in meters and, the horizontal axis shows the angle in degrees. 0° is the angle level at which the center axis of the receiving lens is essentially aimed at the transmitter. 90° means the situation in which the person is turned 90° with respect to the transmitter; in other words the center axle X of the transmitter lens is perpendicular to the line between the transmitter and the receiver. In the figure the continuous line shows a situation when there is no lens in front of the detector. The dashed line represents a case when a lens, chiefly like the one illustrated in Figs " 3 and 4, in front of the detector. The dotted-dashed line represents the situation in which there is a lens of the type illustrated in Figs 1 and 2 in front of the detector. The figure shows that the receiving ability of a bare detector, which receiving ability is here indexed by the so-called range, is worse by approx. half compared with the lenses in accordance with the invention. It can also be stated that the range-angle curve of a so-called cone prism lens (embodi¬ ment of Figs 1 and 2) is considerably more favourable than that of a single cone lens. As the angle grows, the range of a cone prism lens, i.e. a lens in accordance with the embodiment shown in Figs 1 and 2, does not worsen very steeply compared with other cases. Fig. 14B shows the reproduction curve of-a so-called infra-vox device illustrated in Figs 6,7 and 8. The figure shows that the reproduction curve of a device in accordance with the invention is favourable. The output power marked on the vertical axis is rela¬ tively high even at the highest frequencies. The technical speci¬ fication of an infra-vox device in accordance with the embodiment illustrated in Figs 6 to 8 is as follows: TRANSMITTER KH - 185 Frequency range 20 to 11,000 Hz Transmitting frequency 95 kHz Power source transformer 12 V, mains voltage 220/50-60 Hz Modulation FM Weight 105 g Dimensions 107 x 54 x 22 mm RECEIVER KH - 285 Frequency range 20 to 11,000 Hz Reception frequency 95 kHz ' Max. acoustic pressure at 1 kHz 123 dB ■ Power source mini-size battery TR 7/8,9 V, 100 mA Operating time 3 to 5 weeks at 2 to 4 listening hours per day Weight 100 g Headphones 989, frequency range 20 to 19,000 Hz Obviously also such an embodiment is possible in which an additional lens or similar is brought to the described refracting lens surfaces or near them to further enhance the infrared radiation procedure.

Claims: ' Claims 1. An infrared lens for receiving and/or transmitting infrared radiation, characterized in that the lens has such ray-refracting surf ces that radiation aimed at the lens through the refracting surfaces of the lens can be applied to a detector (200) located at the center axis of the lens in such a way that it is possible to use both the infrared rays coming from the hemisphere in front of the device and also the reflected rays, and that, in the middle of the lens, the lens comprises a curved refracting surface (120;440; 592), and a second refracting surface (110;420;591) associated with the first surface, located at an angle (α) with respect to the center axis (X) of the first surface, so that infrared rays coming from the transmitting device can be aimed at the detector (20;200) even when the direction of the center axis (X) of the lens deviates from the straight line between the transmitting device and the detector of the receiving device. (Figs 1,2,5A,5C) 2. An infrared lens in accordance with claim 1, characterized in 0 that the refracting second surface (110,591), associated with the central refracting surface of the lens, which is favourably a segment of s sphere (120,592), located at an angle (α) with respect to the center axis of the lens, is a conical surface (Figs 1,2,5C). 5 3. An infrared lens in accordance with claim 2, characterized in that the lens comprises a third refracting surface which is connec¬ ted with the conical surface (110) , and is curved, favourably spherical, outermost surface of the lens (Figs 1,2). 0 4. A lens in accordance with claim 2 or 3, characterized in that the lens comprises a centrally-located refracting cone surface (110,591), within which cone surface there is an air space (A), the cone angle of the cone, i.e. the angle ( ) between its side line (t) and the center axis of the lens (X), being favourabl -50° 5 to 70°. 5. A lens in accordance with claim 4, characterized in that the angle ( ) is 55° to 60°. 6. A lens in accordance with claim 5, characterized in that the angle (α) is essentially approx. 57°. 7. A lens in accordance with one of claims 1 to 6, characterized in that the lens is made of plastic material, preferably acrylic plastic. 8. A lens in accordance with one of claims 1 to 7, characterized in that the lens is tinted dark with substance well pervious to infrared light.

Inventors: HERMAS KALERVO ALFRED AUGUST, HERMAS, KALERVO, ALFRED, AUGUST
Applicants: HERMAS KALERVO ALFRED AUGUST, HERMAS, KALERVO, ALFRED, AUGUST
Application year: 1987
Main classification: G02B3
IPC codes: G02B3, G02B13, G02B17