Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2000-02-08
2001-07-10
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S227110, C073S862590
Reexamination Certificate
active
06259081
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for receiving a transmission signal and for transmitting an optical beam having an adjustable intensity, wherein the optical beam effects the transmission signal, including a transmitter for transmitting the beam having a controller for setting the intensity, and a receiver for receiving the transmission signal having an analyzer for outputting a threshold signal if the strength of the transmission signal exceeds a predetermined limit value. The invention also relates to a method of using the device.
Such a device is known and is used, for example, in a measuring configuration which carries out measurements in an electrical power distribution installation and includes a corresponding measuring unit that has to be operated at a high electrical potential. The measuring unit is supplied with power through an optical beam. The beam can be fed to the measuring unit for that purpose through an optical waveguide. A transmission signal, which communicates results of measurements of whatever kind, is transmitted as an optical signal, likewise through an optical waveguide, from the measuring unit. In that case, there is no need at all for an electrically conductive connection between a transmitter, which supplies the optical beam serving to supply power, the measuring unit and a correspondingly configured receiver, which receives the transmission signal and passes it on for further evaluation. An optical beam that is considered in that context is, in particular, a laser beam, emitted by a transmitter which is set up correspondingly, for example as a semiconductor laser. The measuring unit correspondingly includes a transmitting and receiving device which, on one hand, receives the optical beam as a power source and, on the other hand, outputs the transmission signal.
It is regularly the case in such a measuring configuration that there is no electrically conductive connection at all between the measuring unit, which is at a high electrical potential, and the remaining parts of the device, that are at normal zero potential. Therefore, it is not easily possible to set an appropriate intensity for the optical beam serving to supply power. As a rule, the setting must be performed manually in that the intensity is adjusted continuously upwards, proceeding from zero, until the measuring unit receives a sufficient amount of power for its transmission signal. Accordingly, it is necessary, when starting up the device, to increase the intensity of the optical beam until a transmission signal having an appropriately high strength, in particular a strength lying above a predetermined limit value, is received.
An additional impediment emerges when a semiconductor laser is used in the transmitter for the optical beam, since the efficiency of a semiconductor laser generally deteriorates due to aging. Therefore, in the course of operation, it is to be expected that the intensity of the optical beam decreases to such an extent that the transceiver can no longer be supplied properly. It has merely been known heretofore to set the intensity of the optical beam manually to a sufficiently high value in order to remedy such a situation.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for receiving a transmission signal and for transmitting an optical beam and a method of using the device, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which permit automatic setting of an intensity of the optical beam and make manual intervention unnecessary.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for receiving a transmission signal and for transmitting an optical beam, the device comprising a transmitter for transmitting an optical beam having an adjustable intensity, the transmitter having a controller for setting the intensity; a receiver for receiving a transmission signal effected by the optical beam, the receiver having an analyzer for outputting a threshold signal if the transmission signal has a strength exceeding a predetermined limit value; a pick-up for outputting a start signal for starting the transmission signal; and a control unit connected to the analyzer, to the pick-up and to the controller, the control unit driving the controller, after reception of the start signal from the pick-up, for causing the controller to set the intensity to a value increasing continuously from substantially zero until the analyzer outputs the threshold signal, and the control unit then leaving the controller unchanged until reception of a new start signal.
In the sense of the invention, the intensity of the optical beam is increased continuously proceeding from essentially zero, that is to say proceeding from a value which does not suffice to effect a transmission signal, and at the same time an observation is made as to whether or not a transmission signal can be received. The increasing of the intensity is continued until a transmission signal of sufficient strength is received and the threshold signal is triggered. The latter stops the process of increasing the intensity.
Accordingly, the invention allows a measuring configuration of the type described, in which the device is integrated, to be reliably activated and deactivated repeatedly many times. Meanwhile, it is ensured during every activation process that an intensity of the optical beam is set which suffices for the purpose of receiving the desired transmission signal. Manual intervention is no longer necessary in this case.
In accordance with another feature of the invention, there is provided a regulator which is connected to the receiver, the transmitter, the analyzer and the controller and enables the intensity to be regulated after the threshold signal has been received. As a result, the device is supplemented by a regulated system which allows the intensity to be regulated in dependence on corresponding properties of the received transmission signal. This refinement is of particular interest for a device which is intended to be operated in each case without a break over comparatively long periods of time, so that impairment of the intensity of the optical beam during operation has to be expected.
In accordance with a further feature of the invention, the control unit has an integrator to which a constant signal can be fed for the purpose of integration and which is connected to the controller in order to set the intensity as a function of an integral of the constant signal. In this case, the constant signal may be a constant direct current and the integrator may be a capacitor with a downstream voltage amplifier having a high input impedance. The integral constitutes a linearly rising voltage signal which can be used in conjunction with a corresponding controller in order to set an essentially linear intensity rise.
In accordance with an added feature of the invention, there is provided a transceiver connected between the transmitter and the receiver. The transceiver receives the optical beam from the transmitter and transmits the transmission signal to the receiver. In this case, it is furthermore preferred for the transmitter and the transceiver to be set up to supply power to the transceiver through the optical beam. In addition, the transceiver preferably contains a measuring unit, from which measurement data can be transmitted to the receiver through the use of the transmission signal. Thus, these preferred developments of the device permit application thereof in the context of the measuring configuration (explained above) in an electrical power distribution network. According to an additional preferred development of the device, it is provided that the transceiver has a configuration for comparing the intensity with the limit value and for adding information about the comparison to the transmission signal. The analyzer and the control unit are set up for the purpose of setting the intensity to a continu
Bartosch Ekkert
Gross Walter
Unterlass Franz-Josef
Allen Stephone B.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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