GB2122044A

GB2122044A - Apparatus for transmitting and receiving infrared signals

Info

Publication number: GB2122044A
Application number: GB8316155A
Authority: GB
Inventors: Horst Bahring
Original assignee: INST PHYS TECH AUFTRAGSFORSCH
Current assignee: INST PHYS TECH AUFTRAGSFORSCH
Priority date: 1982-06-14
Filing date: 1983-06-14
Publication date: 1984-01-04
Also published as: DE8217013U1; GB2122044B; GB8316155D0; JPS594343A

Abstract

The invention relates to an apparatus for transmitting and receiving infrared signals. In the region of the focal point of a concave mirror there is placed a comparatively small infrared sensitive area (9) of an infrared sensitive diode. For the purpose of adjusting said infrared sensitive area its mounting (8) is made longitudinally movable by about 2 to 3 cm along the axis of said concave minor. Several infrared-transmitter-diodes are placed near the edge of the opening of the concave mirror their axes of radiation being generally parallel to the axis of said mirror. Comparatively weak signals incident in the direction of the axes of the mirror can be received by this arrangement. Disturbances by other infrared transmitters, e.g. at transmissions in large workshops by arcs of welding equipment, by lighting up signal lamps, furnaces and incident sun light can be practically fully avoided. <IMAGE>

Description

SPECIFICATION Apparatus for transmitting and receiving infrared signals Background of the invention This invention relates to an apparatus for transmitting and receiving infrared signals for use in duplex telephone systems and diatpgue systems. Many apparatus of this kind are wellknown in various embodiments.

Summary of the invention It is an aim of the invention to improve the performance and to increase the efficiency of the apparatus mentioned above, so that the reception of the infrared signals trasmitted from the opposite station is not affected by other disturbing sources placed in the neighbourhood which occasionally are emitting infrared radiation.

It is a further aim of the invention to achieve this goal by simple constructive measures without additional expenses which might be regarded as considerable in relation to the total costs.

According to the present invention in an apparatus of the kind as mentioned above this apparatus comprises a concave mirror with an opening having a diagonal which is at least four times longer than its focal lengths and an infrared diode being arranged so in the region of the focal point of the concave mirror that the infrared sensitive area which is at most 1/1000 of the area of the aperture is facing the concave mirror, the infrared sensitive area being placed on the front side of a tube which is for purpose of adjusting placed longitudinally movable in the axis of the concave mirror.

In a preferred embodiment of the invention the infrared sensitive area is placed on the inside of the front of a tube having side walls which are permeable to infrared radiation and which is reaching into the interior of the concave mirror through an opening in the apex of the concave mirror and the leads into the infrared sensitive area are conducted through that opening.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing, in which corresponding parts show the same reference numbers.

It has been proved that at an apparatus according to the invention disturbances of the reception by other infrared transmitters, e.g. at transmissions in large workshops by arcs of welding equipment, by lighting up signal lamps, furnaces and incident sun light can be practically fully avoided. Furthermore the additional advantage is achieved, that comparatively weak signals incident in direction of the axes of the mirror can be received with sufficient signal to noise ratio, therefore with the existing transmitting equipment much longer distances can be bridged.

Brief description of the drawing Fig. 1 is a schematic representation of the principle of an infrared transmitting system for duplex-respectively dialogue-communication with transmitting part, receiving part, each with an affiliated optical unit, Fig. 2 is a cross section through a practical embodiment of the optical unit shown in Fig. 1.

Fig. 3 is a part of a cross section through another practical embodiment of the optical unit shown in Fig. 1.

Description of the preferred embodiments The transmitting system shown in Figure 1 consists of one each electronic transmitting part S, one receiving part E and one each optical unit 0 according to Figure 2 and makes possible to transfer datas in dialogue communication between two different places. Good results were obtained with transmitter diode Type LD 271 of Siemens and receiver diode Type BP 104 of Siemens.

The optical unit-according to Figure 2 comprises the infrared transmitter diodes 1 and infrared receiver diodes 2. The receiving diode 2 is placed in the focal plane 3 of a concave mirror 4 with large focal length, having an opening of 1 6.5 cm, which is covered for protection against dust with a cover plate 5 of Plexiglass being permeable for infrared radiation. A tube 8 placed in the axis 6 of the mirror, consisting of a material permeable for infrared light, closed on its front side by a lid 7 serves as carrrier for the receiver diode 2. The diode 2 is mounted on the inside of the lid 7 and the infrared sensitive layer 9 is directed to the apex of the concave mirror 4.Therefore rays 10 incident from the outside are registered in the receiver diode after reflection on the concave mirror 4 and after.having passed the material of the tube. In the shown embodiment the electrical lines 11 to the diode are placed on the inside of the transparent tube.

At the apex of the concave mirror 4 a tube 8 is screwed into the mount 13, which is connected with the concave mirror. Therefore by rotation of the tube 8 a precise adjustment of the receiver diode can be made along the axis:.6 of the mirror.

After the receiver diode 2 has been adjusted in the focal plane 3 the tube 8 is fixed by tightening the look unit 14. The infrared transmitter diodes 1 are placed in small distances from the concave mirror. After the receiver diode 2 has been adjusted in the focal plane 3 the tube 8 is fixed by tightening the look unit 14. The infrared transmitter diodes 1 are placed in small distances from the concave mirror. To increase the efficiency of the directional beam they are placed in the focal point of each one parabolic reflector 1 5 having short focal length and being opened in the direction of the radiation.

If the shading of the arriving radiation by the electrical lines is to be reduced somewhat, the wires should be conducted along the axis 6 of the mirror from the apex to the cover lid 5 across the opening of the mirror to the outside.

Figure 3 shows another practical embodiment.

In this the receiver diode 2 is mounted by means of a sleeve 12 being fixed on the cover lid 5 and the lead-in wires 11 are conducted from the outside in radial direction over the cover lid through its central opening and through the interior of sleeves 1 2 to the receiver diode 2.

While the invention has been illustrated and described as embodied in an apparatus for transmitting and receiving infrared signals, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the

Claims

appended claims. Claims

1. Apparatus for transmitting and receiving infrared-signals for use in duplex telephone systems and dialogue systems, comprising in combination a concave mirror with an opening having a diagonal which is at least four times longer than its focal lengths; an infrared-sensitive-diode placed in the region of the focal piont of said concave mirror, the infrared-sensitive area being at most 1/1000 of the area of the aperture of said mirror is facing that mirrdr, and placed on the front of said infrared-sensitive diode which for the purpose of adjusting is made longitudinally movable in the axis of said concave mirror.

2. Apparatus according to claim 1, comprising an infrared-sensitive diode having the infraredsensitive area placed within a tube having side walls Dermeable to infrared-radiation is protruding into the inside of said concave mirror through an opening in the apex of said mirror, the leads-in to the infrared-sensitive area being conducted through said opening (Figure 2).

3. Apparatus according to claim 1, comprising an infrared-sensitive diode having its infraredsensitive area on the outside of the front of a longitudinally adjustable sleeve which protrudes into the inside of the concave mirror through a central bore of a plate covering the hollow side of said concave mirror, the leads-in to the infraredsensitive area being conducted in generally radial direction over the opening of said concave mirror and through said bore (Figure 3).

4. Apparatus according to any preceding claim, comprising several infra red-transmitter-diodes being placed near the edge of the opening of the concave mirror their axes of radiation being generally parallel to the axis of said mirror.

5. Apparatus for transmitting and receiving infrared-signals for use in duplex telephone systems and dialogue systems, substantially as hereinbefore described with reference to Fig. 1 and Fig. 2 or Fig. 1 and Fig. 3.