Abstract: A heater circuit (H) according to the invention comprises a stabilizing power supply (SPS) with a control input (CT) which receives a control signal (Cs) to control the value at which the heater voltage (Vh) has to be stabilized. A timing circuit (TC) generates the control signal (Cs) such that the heater voltage (Vh) has a nominal value (Vhn) in a normal operation phase, and such that the heater voltage (Vh) has a boost value (Vhb) higher than the nominal value (Vhn) during a boost period (Tb) of a start-up phase (Ts). The normal operation phase is defined as the phase during which the heater (HE) is sufficiently hot to enable display of a picture with good quality. The start-up phase (Ts) is the phase during which the display apparatus starts up and the heater (HE) warms up.

Abstract: As a white light source, the lighting system (1) has at least three light-emitting diodes (6, 7, 8) for providing visible light at preselected wavelengths. The invention is characterized in that the lighting system (1) is provided with at least one fourth light-emitting diode (9) which, in operation, emits visible light in a further wavelength region, the maximum of the spectral emission of the fourth light-emitting diode (9) lying in the further wavelength region from 575 to 605 nm. Preferably, the further wavelength region ranges from 585 to 600 nm. Preferably, the color rendition of the lighting system (1) is above 60. Preferably, the luminous efficacy of the lighting system (1) is above 30 lm/W, preferably above 40 lm/W. In another preferred embodiment, the color temperature of the lighting system (1) can be adjusted by selectively switching the light-emitting diodes (6, 7, 8, 9).

Abstract: A system useful echographic examination simulation and training includes an ultrasonic echograph (31) equipped with a TV monitor (32), a 3D probe (33) for analyzing a subject, acquisition means (39), a memory card (42) storing the detected acoustic lines and a workstation (34) with central processing unit (35) and 3D echography memory (38). For reading the latter memory (38), the system includes a viewing device including a dummy (56) simulating the subject, and a 3D orientation sensor (52) connected to the workstation via a 3D coordinate indicator (54) and display means (29) of the workstation, which make the sectional plane which the sensor defines on the dummy correspond to the equivalent plane contained in the form of voxels in the echography memory (38), and display this plane on the screen of the TV monitor (32).