DE1090728B - Arrangement for changing the retroreflective capacity of reflectors for ultrashort waves, preferably of the centimeter area, with the help of an optical light source - Google Patents

Description

The invention relates to reflectors for ultrashort electromagnetic waves, in particular reflectors to identify certain geographical points of traffic routes, these reflectors for example in connection with self-radiating optical identification elements as combined electro-optical Identification beacons or buoys are used for traffic safety in shipping.

In many cases it is desirable to use self-radiating or radiation reflective, i.e. H. active or passive, optical signals, in particular traffic signals in the form of lamps or signs, with additional active or passive electromagnetic signals, in particular radar signals in the form of transmitters or reflectors, with these signals often being assigned special identification signals should. The identifier of the radar signal here preferably corresponds to that of the optical signal.

According to the invention, an arrangement for changing the retro-reflecting capability is electrical for this purpose controllable reflectors, preferably for centimeter waves, proposed in conjunction with optical Signals work, with control of the retroreflectivity being done by circuits that operate through Photo elements are fed, which are mainly exposed to the radiation of the associated signal light source are.

Thus, in the arrangement according to the invention, the operation of a modulated reflector arrangement necessary power source represented by at least one photo element, its electromotive force depends on the lighting intensity by the signal light source. By influencing the reflection properties of the electrically controllable reflector in the Cycles of the electromotive force of the photo element, which fluctuates in the rhythm of the optical identification the analog electromagnetic identifier of the reflector of the signal light source can be synchronized control with the optical identifier.

According to a further advantageous embodiment of the invention, the is synchronized with the optical identifier fluctuating electromotive force of the photo element is not used for direct modulation of the electrically controllable reflector, but for charging an accumulator is provided, which is only used for direct current supply of the electrically controllable Reflector is used. This reflector can possibly easily have its own identifier which differs from the optical one are assigned, which is controlled for example by means of time circuits known per se.

The main advantage of the arrangement according to the invention over combined electro-optical identification signals, the constant current source from a built-in source or connected via long-distance lines

Arrangement for change
the reflectivity of reflectors

for ultrashort waves,

preferably of the centimeter area,

with the help of an optical light source

Applicant:

Telefunken GmbH,
Berlin-Charlottenburg 1, Ernst-Reuter-Platz

German Bernhard Koch, Lörrach (Bad.),

and Günter Schultze, Haltingen (Bad.),

have been named as inventors

are fed, with the energy to operate and control the identifier of both the optical signal and the electrically adjustable reflector is taken from this constant power source, is located in the possibility of their use in identifiers that are not operated electrically, for example for navigation signs that are equipped with propane gas lamps.

The electronic control of the reflection capacity of reflectors required in the invention is known per se. For example, there is an arrangement for periodic or non-periodic change the reflectivity of reflectors for electromagnetic waves, especially in the centimeter wave range been proposed for the identification of radar targets, in which the reflector by a line element corresponding to the wavelength of the incident radiation is shown whose Adaptation to which the high-frequency energy absorbs

- Mending element (antenna) by inserting in its high-frequency resistance by means of one of a self-excited oscillating circuit generated electromotive force changeable switching elements, in particular semiconductors, is influenced, preferably the adaptation of the line element influencing the antenna with the element causing the self-excitation of the oscillating circuit is identical.

In a further advantageous embodiment of the invention, such a controllable reflector is preferred provided with a semiconductor through whose

009 627/299

due to the optical effect of the signal light source controlled variable resistance the reflection properties of the reflector can be changed according to the code. Such an identifier can, however can only be detected with a radar device aimed at the target for a longer period of time, however not with the usual radar devices with a constantly rotating antenna.

Another advantageous one is suitable for use in conjunction with rotating search antennas Embodiment of the invention. Since a higher-frequency identifier must be used here, which already occurs during of the period of sweeping over the main lobe of the antenna directional diagram over the reflector is, the photo elements in this embodiment of the invention do not directly control the reflector, but trigger an oscillating circuit, for example a low-frequency transistor oscillator, whose oscillating current in turn controls the modulated reflector in time with an audio frequency.

Furthermore, an embodiment of the invention is proposed in which the variable resistor of the semiconductor is represented by a phototransistor, which in turn is of course part of it can be an oscillating circuit and itself supplies the DC energy required for this.

With reference to the figures, the mode of operation of the arrangements according to the invention is for the better Understanding the same explained in more detail.

Fig. La shows the change in light intensity over time the signal light source which simultaneously illuminates a photo element;

Fig. Ib shows the time dependency of the semiconductor impedance as a result of illumination from the signal light source;

Fig. 2 a shows the temporal change in the light intensity of the signal light source, which is also a Modulation device influenced;

Fig. 2 b shows the time dependence of the reflection factor in the identification cycle of the signal light source affected modulation circuit;

Fig. 3 shows a schematic representation of a circuit arrangement for charging an accumulator, feeds the modulator influencing the electrically controllable reflector.

Fig. 1 a shows the time dependence of the light intensity of the signal light source, i.e. H. the identifier, shown. This signal light source simultaneously illuminates a semiconductor and thereby changes its impedance in time with the identifier, as shown in Fig. 1b. The semiconductor is for the electronic control of the reflectivity Used by reflectors, in which the reflector passes through one of the wavelengths of the incident Radiation corresponding line element is shown, its adaptation to the antennas by means of the variable impedance of semiconductors is influenced, so it is, for example, a horn antenna acts, to which an A / 4 line is coupled, inside of which there is a transistor, the is an element of an oscillating circuit.

According to a further embodiment of the invention, a modulation circuit with a self-oscillating Transistor in rhythm with the light intensity of the signal light source, which fluctuates according to Fig. 2a influenced by this lighting, and there is a modulated change in the reflection factor, as shown in Fig. 2 b.

To with a non-electrically operated signal system when feeding the electrically controllable Reflector influencing modulation device to be independent of the daylight that may be is used via photo elements to charge accumulators, a charger is shown in Fig. 3 proposed, which consists of the photo element 1, the rectifier 2 and the accumulator 3. Of the Rectifier 2 prevents the accumulator from being discharged via the internal resistance of the photo element 1. Of course, in addition to the signal light source used for this purpose, the accumulator can be charged daylight can also be used.

Claims (4)

PATENT APPROACH: 1. Arrangement for changing the reflectivity of electrically controllable reflectors, preferably for centimeter waves that work in conjunction with optical signals, characterized in, that the control of the retroreflective ability is done by circuits that are photo elements are fed, which are mainly exposed to the radiation of the associated signal light source are. 2. Arrangement according to claim 1, characterized in that one in its high-frequency resistance electrically controllable switching element of known design, preferably a semiconductor diode, directly is fed by the photo element. 3. Arrangement according to claim 1, characterized in that one for changing the reflectivity Serving, per se known oscillating circuit, preferably using semiconductors, is fed through the photo element. 4. Arrangement according to one of claims 1 to 3, characterized in that the photo element is replaced by a phototransistor, which itself represents the variable impedance. Considered publications:
German Patent No. 543,376;
British Patent No. 682,652;
Electronics, Nov. 1955, p. 20;
"Radiomarkt" (supplement to "Electrical engineering") (Würzburg), October 9, 1954, pp. 67 to 69. 1 sheet of drawings © 009 627/299 10.60