Abstract: A digital control circuit uses a single infrared detector to control the clock pulse on a digital counter so that the sensitivity control is based on the length of time a change in infrared radiation persists. A pyroelective detector is located in a voltage divider and the intermediate voltage of the divider is digitally compared to the intermediate voltage in a fixed divider as a digitaly controlled pulse is applied to both dividers. Either an increase or a decrease of infrared radiation causes the digital circuit to permit the counter to be activated.

Abstract: A digital infrared detector circuit which converts changes in detector current to time varying pulses and uses feedback to adjust the coincidence of a reference signal with the trigger signal to accommodate to circuit variations caused by changes in infrared detector sensitivity or ambient temperature. To supply a highly accurate feedback reference signal an internal high frequency oscillator is used for feedback control and counted down to furnish the reference signal. The conversion from detector current to time is accomplished by using the detector to discharge an accurately charged capacitor and measuring the time to recharge the capacitor.

Abstract: A digitally controlled ambient light detection circuit for an infrared intrusion detector. A light dependent resistor is used as a charging circuit for pulse driven capacitor on the input of a digital buffer circuit so that the time of reaching the threshold voltage of the buffer varys with the light falling on the light dependent resistor. The buffer output is then compared to a reference pulse which is synchronized with, but delayed from, the capacitor charging pulse. If the buffer output occurs after the reference pulse it indicates low light, and an output signal is generated to activate the infrared intrusion detector.

Abstract: A relay switch in an ac main line has a dc-powered applying for applying amplified control sensor signals to the control circuit of the relay switch. To provide dc power for the amplifier when the relay switch main controlled current conduction path is conductive, a current transformer primary winding is arranged in series with that path, and the voltage appearing across the secondary winding is rectified. To provide dc power for the amplifier when the relay switch main controlled current conduction path is non-conductive, an open-circuit voltage related to that appearing across the open-circuit non-conductive path is rectified. To permit the use of one rectifier for developing dc power for the amplifier it is advantageous to apply the open-circuit voltage to the secondary winding of the current transformer through a dc-blocking capacitor with sufficient ac impedance to restrict ac flow across the open-circuit relay switch path.

Abstract: An electrostatic shutter tube comprises a photocathode adapted to emit electrons along a path as an electron image in response to a radiant image incident upon the photocathode. A phosphor screen is spaced from the photocathode and is adapted to emit a light image in response to the impingement of the electron image thereon. A shuttering grid is disposed in the electron path between the photocathode and the phosphor screen to control the emission of the electron image. An anode member adjacent to the screen has therein a pair of primary deflection plates disposed along the electron path for deflecting the electron image in a first direction across the screen. A pair of secondary deflection plates are disposed within the anode member, along the electron path, in a cross-over region of the electron image.

Abstract: A method of aging a cathode of an evacuated cathode-ray tube having an electron gun including a heater, a cathode, a control electrode, a screen electrode and a focus electrode is proposed. The cathode and the focus electrode are interconnected. A first potential is applied to the heater while a second potential is applied to the cathode and focus electrode. At the same time, a third potential, more positive than the second potential, is applied to the control electrode. A fourth potential is applied to the screen electrode. A change in the fourth potential is sensed and the sensed change in the fourth potential is used to generate a control signal to vary the first potential to the heater. The aging process is terminated when the control signal causes a predetermined value of the first potential to be achieved. A structure to provide at least some of the above-indicated potentials as well as to sense the change in one of the potentials and to generate the control signal is also disclosed.