Abstract: An active transponder device comprises a CMOS integrated circuit including means for receiving an input signal including coded information, a memory for storing said information, and transmitter means for transmitting an output signal including said information, the input signal and the output signal being both low frequency induction communication signals.Normally, the output signal is emitted in response to an interrogation signal received via the receiving means, and is formed by modulation of that signal with said information after readout from the memory. The transponder operates inherently synchronously, using a single master clock signal which is generated either in an interrogation transmitter or in the programmer for injecting the coded information.The integrated circuit has a second receiving means used in the injection of the coded information. The injection of a clock-pulse which is in synchronism with the input signal enables the memory to receive the coded information.

Abstract: An apparatus for measuring the axial length of the eye is disclosed. The apparatus comprises circuitry for transmitting repetition ultrasonic pulses along the ocular axis of the eye and for receiving echo pulses reflected from the retina of the eye. The reflected echo pulses are then amplified. Gate circuits receive the amplified signals and pass logic signals triggered by retinal echo pulses exceeding predetermined thresholds. A digital counter displays the axial length of the eye as a function of a distance travelled by the retinal echo pulses. A time slot is generated during which echo pulses originating from the posterior wall of the eye can be received, and an echo triggered gate width generator enables the passage of logic signals triggered by retinal echo pulses exceeding a threshold in the generated time slot.

Abstract: A presence sensing system comprises a detector having a transmitter for transmitting an interrogation signal to an area to be kept under surveillance and a receiver for receiving a presence indicating signal. A receiver/transmitter device the presence of which is to be detected is adapted to receive the interrogation frequency and to transmit a presence indicating signal in response thereto. A phase locked loop circuit has a first input coupled with the output of the receiver a second input for a reference signal, and an output for providing a phase locked signal which is indicative of phase coherence between the signals on the two inputs. A frequency generator has an output coupled with the second input of the phase lock loop and an alarm is actuable in response to the phase locked signal.The invention also includes the presence sensing detector described in the above system.

Abstract: A cathode ray tube is disclosed which is relatively flat in the viewing direction, including a transparent envelope having at least one generally flat section, a screen arranged within the envelope, an electron gun for projecting an electron beam along a path substantially parallel to the plane of the screen, and first and second deflecting means for causing the beam to scan a line and a frame, respectively, characterized by the provision of a single conductive member of a given potential forming a beam directing electrode spaced from the screen and arranged such that the path of the electron beam lies between the electrode and the screen.