Abstract: The present invention relates to a device for illuminating at least one surface, which includes a light source and a reflector in order to focus the light rays emitted by the source. In said device, the focal plane of the reflector lies between the light source and the said surface and it includes, positioned close to the focal plane of the reflector, a means forming a second light source.

Abstract: In a television receiver comprising a horizontal deflection circuit (2) associated with a flyback transformer (9), the horizontal deflection circuit comprises a switch (6) which is controlled by a control signal (Hdrive) generated by a deflection control circuit (1). The deflection control circuit generates a phase difference signal (Vcomp) which is a function of the phase difference of a horizontal synchronisation pulse and a flyback pulse and generates the control signal (Hdrive) as a continuous function of the phase difference signal (Vcomp). The deflection circuit is further arranged to generate at least one discrete phase jump of the control signal (Hdrive) when the phase difference signal (Vcomp) lies outside of a range of preset values (Vlow, Vhigh).

Abstract: The invention relates to a process for protecting an information item transmitted from a security element to a decoder and a protection system using such a process. The information item is protected by encrypting within the security element the information item to be transmitted to the decoder and by decrypting this information item within the decoder. The invention applies to conditional-access systems.

Abstract: The subject of the invention is a communications device connected in parallel with at least one item of communications apparatus on a transmission line (L1, L2). The device and the apparatus conform to a given template in terms of DC components. The device in accordance with the invention is characterized in that it comprises means (18, R1, R2, R3, D5, DZ) setting the operating point (X) in terms of DC component of the said device alone outside regions of the said template where the DC component of the current may be zero, means (R2, D6, D7, R4, 19, 20) of determining the DC component of the current flowing in the said device, means (20) of detecting a variation in the said DC current component. The invention applies particularly in the field of communication via the switched telephone network.

Abstract: The protection circuit comprises a storage capacitor which is coupled with a terminal of a secondary winding which charges said storage capacitor during the on-interval of the switching transistor. During the off-interval of the switching transistor the charge of the storage capacitor is fed to the driver stage or the control capacitor for closing or keeping closed the switching transistor when one of the secondary windings has a short circuit.

Abstract: A block based signal compression system, as for example for coding video signal, and employing quantization of codewords or transform coefficients includes circuitry for adaptively controlling the quantization. Adaptivity of quantization is made a function of several parameters. One parameter is coding cost or bandwidth, wherein coding cost is generated on a macroblock basis but averaged over a window of macroblocks centered on a macroblock currently to be quantized. Another parameter is block or macroblock motion attributes, wherein block motion attribut values are used to modify the quantizing function.

Abstract: A device for estimating motion between a current image and a previous image by block matching, the images being split into blocks. The device includes a processing circuit for each candidate motion vector and at least one memory. Each processing circuit calculates errors between a block of the current image and the block designated by a respective candidate motion vector in the previous image. The processing circuit successively receives pixels of the current image according to a line scan at a first input and corresponding pixels of the previous image identified by the associated candidate motion vector at a second input. The processing circuit calculates partial sums at the end of line of each block of the current image corresponding to accumulated errors for this block. The processing circuits further include an output for delivering the partial sums and a third input for receiving the partial sums.

Abstract: The disclosure is a stepped rectification high-voltage transformer including a secondary step-up winding in which at least two output diodes connected to two different stages of this secondary winding are located in a same axial level and perpendicular to the potentiometer block forming part of the insulating casing. The invention is applicable notably to the power supply of television cathode ray tubes.

Abstract: The disclosure relates to a device for illumination of a screen, notably a liquid-crystal screen. It includes a light integrator that receives a light beam from a source and outputs an illuminating beam for the screen. The light integrator makes use of lenses, but has no lenses in the parts of the beam where the energy flux is weak, which enables more uniform illumination of the screen. To improve the contrast of the illumination of the liquid-crystal screen, the whole illuminating beam is directed onto the screen at an angle to the optical axis of the system. The invention is applicable to liquid-crystal screens.

Abstract: A scan frequency detector is responsive to a horizontal synchronization signal to generate a data signal that is indicative of the horizontal scan frequency. A digital-to-analog (D/A) converter produces from the data signal an analog, output signal at a first level, when the horizontal frequency is within a first range of values, at a second level, when the horizontal frequency is within a second range of values and at a third level, when the horizontal frequency is within a third range of values. A first switch of a switched S-capacitor arrangement, is turned on, when the output signal is at the first level. The first switch and a second switch of the switched S-capacitor arrangement, are turned on, when the output signal is at the second level. Both the first and second switches are turned off, when the output signal is at the third level. The third and second levels are distinguished by a level detector that includes a zener diode.

Abstract: The disclosure relates to a recording and reading apparatus constituting a kind of video reservoir in the home of the consumer. Thanks to a large-capacity storing technique with suitable technical device, broadcasters transmit numerous programs via specific channels and the consumer may control the content of his reservoir (by recording, reading and erasing programs). The invention is applicable to on-demand video in the consumer's home with a video reservoir constituting a video-library that is regularly updated by broadcasters and/or by the consumer himself.

Abstract: An optical polarization device includes a source of light emitting a non-polarised light beam. A polarization separator reflects one polarization component of the light beam and transmits the other polarization component. A reflection means receives the component reflected by the polarization separator, rotates its polarization plane through 90.degree., and returns it to the polarization separator. The polarization separator is a plane element. The reflection means is positioned on the source side of the separator and consists of a regular network of prisms, each partially covered with a reflective layer associated with a .lambda./4 plate.

Abstract: Known LCD projectors, used for example in TV sets, can only be manually adjusted for the compensation of the changing color spectrum of the lamp due to its aging process. An LCD projector according to the invention further comprises an image sensor to measure the light intensity of the lamp. In a color adjusting circuit the image color is compensated as a function of the measured signal by controlling the LCD valve.

Abstract: A speech based man-machine communication system is given, comprising more than one controllable device provided with speech synthesis function. Each of the devices in question is provided with its own unique voice pattern. The devices are connected via a bus, so that a central authority handles all the requests from the user. Because the user uses his natural language, commands can be ambiguous. Therefore an algorithm for handling ambiguous situations is provided.

Abstract: The conditional access system of the present invention allows a service provider to supply services, which may be scrambled by a control word, only to those users who have acquired entitlements to these services. The control word is supplied in Entitlement Control Messages (ECM) after having been encrypted using a key. The entitlements of each user are forwarded in Entitlement Management Messages which contain the key. The conditional access system verifies and validates the ECM and EMM prior to processing the control word.

Abstract: The invention is a process and apparatus for estimating a bit budget in a circuit for compressing digital data, especially digitized television signals. Signals represented by N-bit coded samples, are estimated based upon the probability of a bit of given order having a given value (0 or 1) out of M binary words representing M samples of the signal. An entropy calculation is performed on the basis of the probabilities corresponding to the N bits with the sum of all the entropies corresponding to the desired estimate.

Abstract: The system includes a plurality of decision units, at least one verification unit, and at least one counting unit, the units being functionally and structurally separate from each other. Each decision unit includes means for producing a source information item and an identity information item, and means for enciphering this source information item in such a way as to render it essentially indecipherable by the verification unit but decipherable by the counting unit. The verification unit includes a file which includes the identities of the decision units, means for checking the identity of the decision unit from which an incoming message originates, and means for compiling an anonymous derived message which is essentially devoid of any identity information item decipherable by the counting unit.

Abstract: The disclosure relates to a method of synchronization of clocks wherein, in a system including a digital decoder of a receiver equipped with a sampling clock and a digital encoder of an transmitter also equipped with a sampling clock, said method includes the following stages: in the transmitter, coding by packets of samples of a signal by time intervals of predetermined duration and triggering of the transmission of a data frame when a packet of data is ready to be sent; in the receiver, detection of start of said frame, and generation of a reference signal following said detection, said reference signal being used to correct the clock of the receiver.

Abstract: A radiation emitting device, such as an LED, is optimally driven in dependence on the value of a carrier frequency of a signal to be transmitted. The current provided to the radiation emitting element is controlled responsive to the carrier frequency. When using an LED, the current value is increased with decreasing duration of current flow. The apparatus is usable for remote controls suitable for controlling two or more devices.