Abstract: The present invention is with respect to a reflectance measuring head that is designed for stopping the production of false readings by regular (as opposed to diffuse) reflection and shiny parts of the sample without using normal shine traps or diaphragms. False readings as produced by regular reflection, by surface grain or structure and by inhomogeneity of the surface of the sample are furthermore put an end to by having a number of transmitters placed at an equal distance from one receiver or having a number of receivers placed at an equal distance from a transmitter. A more specially useful effect is produced if a number of transmitters and a number of receivers are placed alternately in the form of a matrix.

Abstract: To be certain of an even illumination of a field of measurement for measuring reflectance and to make it possible to have reflectance measuring heads of small size, the said field is illuminated with a number of discrete beams coming from transmitters, whose emission faces or areas are placed in a plane that is parallel to the plane of the said field. Preferably light guide cables are used for the transmitters and receivers.

Abstract: In known apparatus for taking reflectance readings the accuracy is very highly dependent on the distance between the transmitter and/or receiver area, on the one hand, from the surface whose reflectance is to be measured on the other. In the invention, in the field of measurement, the beam from a transmitter has superimposed on it the beam of at least one further transmitter so that within a wide range of operation readings are made independent of the distance between the said field on the one hand and the transmitter and/or receiver plane on the other and for this reason there is a deep range of measurement, that is to say compensation of depth. Preferably the transmitters are placed axially symmetrically with respect to the axis of the received beam (beam coming from the sample) or planarly symmetrical with respect to a plane containing the axis of the said beam.

Abstract: For switching over from playback of the owner's announcement text to recording a message from a caller, a pause of defined length is present on the announcement tape between the first and second (or end) parts thereof. This pause is recorded and on every run of the announcement tape through the apparatus the reading, recorded for the length, undergoes comparison with the pause of the announcement tape being transported. When the two values are the same, switch over takes place. In this way, it is possible to make certain of switch over without being dependent on the tape speed, and the circuit system may be made very much less complex.

Abstract: Plural transmitters, which transmit signals to a common receiver, transmit their signals in a fixed time-staggered pattern. As a result, the individual signals which are transmitted by the respective transmitters do not interfere with one another or influence one another. Between the fixed time-staggered signals, which are sent out, for example, as standard signals to facilitate routinelike monitoring, signals of a higher priority, for example alarm signals, can be transmitted without any time delay. This is particularly suited for use in connection with a personal security and monitoring system, in which the function monitoring of the unit and the wireless connection between several transmitters and a receiving center must constantly be monitored, and signals of a higher priority, namely alarm signals, are transmitted without delay.

Abstract: A centrifuge with swinging sample vessels has a rotor with curved rolling support faces on which the sample vessels may be rolled as they are moved into and out of a horizontal position by centrifugal force on centrifuging. Because of the use of a system with rolling structures for swinging of the vessels, a design of centrifuge is produced which is simple in structure, needs little upkeep and whose rotor is low in weight and does not have any cup supports or the like for supporting the sample vessels.

Abstract: A method for monitoring the exposure of an individual person to toxic gases is carried out such that the gas concentration is continuously measured with a sensor for the specific gas, recorded and the measured values then read and evaluated. Instantaneous values of the concentration are periodically scanned, temporal mean values of the instanteous values are formed over a predetermined time interval, these mean values are stored and an alarm triggered if the instantaneous value and/or the mean value exceeds a predetermined critical value over the time interval or an integral multiple thereof.

Abstract: In an apparatus for process analysis, a test substance is removed from the process stream by a probe and fed to an analysis instrument with a measured value display. Upstream of the analysis instrument, the test gas is conveyed through condensers. A monitoring unit is coupled to the analysis instruments and the processing chain without influencing the flow of data from the analysis instrument to the measured value display. The monitoring unit receives information about the entire apparatus via status sensors which are incorporated into the processing chain and into the analysis instrument. Depending on this information, the monitoring unit can intervene via solenoid valves, switches and motor potentiometers into the apparatus and alter its operation. The condition of the apparatus can also be displayed.