Abstract: The shutter comprises a first and a second blind (47, 48) extending in parallel planes close to each other and wound on at least one roller (6, 9) on each side of the exposure window, which blinds each have an edge (55, 56) which edges define a shutter slit (5) between them. The roller of the first blind is driven by a first pinion (7) which is rigidly coupled to a drive mechanism (31). In accordance with the invention the shutter comprises a second pinion (11) which is rotationally coupled to the first pinion, and a third pinion (14) which is coaxial with the second pinion and which is driven by the second pinion via an angular-positioning device (59) which drives the roller (9) of the second blind; the shutter also comprises tension means (49, 52, 53) which maintain each blind in its respective plane. In this way an accurately variable width of the shutter slit can be obtained.The shutter is used in cameras for aerial or marine surveillance.

Abstract: A blackened optical system includes a transparent substrate having a front side provided with at least a pair of elongate ribs forming therebetween an elongate groove. An amount of optically black discrete particles for absorbing visible ambient light is disposed in the groove. The particle amount is contained within the groove by means of a skin which extends between the ribs and over the groove.

Abstract: A frequency synthesizer of the pulse cancellation type which predicts the phase jitter that will be caused by the pulse cancellation and generates a compensation signal C which precisely compensates for the phase jitter. The compensation signal is derived directly, from a pulse train in the synthesizer which itself contains jitter, via a d.c. removal circuit DCR and an analogue integrator INT.

Abstract: A magnetic head (32) includes a magnet core (30) of ferrite and a layer of a bonding material (28) consisting of glass in the gap-forming area of the magnet core (38). In order to ensure that the ferrite is not attacked by the glass during the bonding process and that the temperature adjustment during the bonding process is not too critical, double layer diffusion barriers are provided between the layer of bonding material (28) and the core parts (10), (10'), respectively. Each barrier is formed by a layer of silicon nitride (26) on the side of the bonding layer (28) and a layer of silicon oxide (24) on the side of the core.

Abstract: A frequency synthesizer includes frequency reduction means which includes a pulse swallow circuit PS which cancels cycles from the frequency Fo under the control of a rate multiplier RM. To prevent phase jitter at the output of phase comparator PC due to the cancelled cycles, a compensation signal HP is derived from a swallow command signal A and from a multiplying fraction n/x of the rate multiplier. In order to keep the DC level of the signal HP constant, the signal HP is bidirectional with respect to a mid-point voltage level and the total area of the pulses in one direction is the same as the total area of the pulses in the other direction. The invention is applicable to both phase locked loop synthesizers (FIG. 2) and direct synthesizers (FIG. 11).

Abstract: A holder for a discharge lamp having a bi-pin base includes a housing with two pairs of opposed walls connected to form a lamp base receiving recess therebetween, a resilient clip and an opposed pair of electrical conductors. The clip and the conductor pair are disposed in the housing for gripping the lamp base and for electrically engaging the lamp pins, respectively, of a lamp received into the holder.The housing further includes four internal cooling passages partly formed by two directly facing and opposed rib pairs provided on the respective housing walls. The passages open to the ambient atmosphere. The resilient clip has good thermally conductive properties.

Abstract: A lens system is provided which is suitable for back-projecting an enlarged image of a TV cathode ray tube (CRT). The lens system includes a concave CRT face plate FP and three lens elements L1, L2, L3. L1 and L3 are each of positive power and each have one aspheric surface. L2 is between L1 and L3 and also has one aspheric surface. The powers of the elements are chosen so that0.50K<K.sub.1 <0.90K-0.35K<K.sub.2 <0.20K,and0.70K<K.sub.3 <1.0Kwhere K.sub.1 is the power of the first element remote from the object surface, K.sub.2 is the power of the second low power element, K.sub.3 is the power of the third element adjacent to the object surface and K is the total power of the projection lens.

Abstract: A magnetic head for a magnetic recording and playback device includes a core having two core parts which are spaced from each other and between which a transducing gap is formed. The core consists of a (preferably monocrystalline) zinc-ferrous ferrite. A preferred range of compositions is defined by the formulaZn.sub.a Fe.sub.1-a.sup.II Fe.sub.2.sup.III O.sub.4, wherein 0.1.ltoreq.a.ltoreq.0.4.The Zn-ferrous ferrite may further comprise additions of Co.sup.II.

Abstract: A display panel comprises a plurality of semiconductor crystals (6) fixed at the bottom of reflecting cavities (3).The cavities (3) are obtained from strips supporting two rows of complementary half-shells (1, 2) and supporting the connection means of the semiconductor crystals (6).

Abstract: A connection socket (11) includes an electrical component (16) having a control shaft (18, 35) which is coaxial with a rotatable cylindrical plug (12) in a recess (19) of the connection socket (11). The component (16) can be adjusted by rotation of the plug (12) which engages a coupling member (30) on the control shaft (18, 35) of the component (16).

Abstract: For trapping loose particles remaining in the envelope of an electron image tube after manufacture or subsequently formed therein, the envelope has a trapping space (49 or 50) which is readily accessible to the loose particles but wherefrom the loose particles can escape only with great difficulty, and which is such that particles trapped therein will not substantially adversely affect normal operation of the tube. The entrance of the trapping space suitably is a funnel-like slit (46 or 48) directed towards the interior of the trapping space (49 or 50). The trapping space (49, 50) is preferably in a region of the envelope free of strong fields which occur during normal operation of the tube.

Abstract: In FM transmitters, particularly land mobile FM transmitters, wherein a speech signal is pre-emphasized between 300 Hz and 3 kHz, whereafter it is filtered to provide a sharp cut-off and wherein the maximum peak frequency deviation is limited in order to maintain channel integrity, the level of undistorted speech can be raised to within 90% of the transmitter peak deviation by directly connecting an amplitude limiter to a filter amplifier which behaves as a level sensitive filter when the speech signal has been limited and prevents ringing and overshoot from occurring. The output from the filter amplifier is coupled to a low pass filter, typically a fourth-order Butterworth filter, via an attenuator which reduces the amplitude of the signal to prevent the onset of further clipping.

Abstract: A lens system is provided which is suitable for back-projecting an enlarged image of a TV cathode ray tube (CRT). To achieve a compact cabinet design 1 for such a projection television set, a short projection throw and a wider projection angle are required, together with a wide aperture (F/1) for a bright projected picture and with a definition sufficient to resolve 625 line television pictures. The lens system comprises a concave CRT face plate FP and only two lens elements L1, L2, each of positive power and each having one aspheric surface, the powers of the elements being chosen so that0.4K<K.sub.1 <0.60K and0.75K<K.sub.2 <1.05Kwhere K.sub.1 is the power of the element remote from the object surface, K.sub.2 is the power of the element adjacent the object surface and K is the total power of the projection lens system.

Abstract: A method of electrophotographic printing of electrically stored information by means of a cathode ray tube. The tube is controlled so that each time only one picture line of the information on the display screen is activated several times in succession. Thus, the transport movement of the record carrier is continuous. The optical system provided between the cathode ray tube and the record carrier may be constructed to be rigid, so that on the record carrier there is formed an image whose individual pixels represent a small line which consists of several overlapping dots. The necessary brightness is achieved by using a cathode ray tube having a wide display screen on which the picture lines to be transferred to the record carrier are displayed with a 1:1 ratio. Furthermore, the display screen is provided with a coarse-grained phosphor of the zinc sulfide type which has a high light yield.

Abstract: In a device for displaying three-dimensional pictures, N (with N=2, 3, 4 . . . ) recorded images corresponding to different spatial observation positions are displayed on one or more intermediate display screens (3, 4, 5, 82, 83, 84). The device comprises a viewing screen (6) having lens elements (20, 30) via which corresponding picture segments of the recorded images are displayed. An optical coupling (8, 44) having a plurality of light conductors (8) exists between the viewing screen and the intermediate display screen(s). The light conductors unambiguously associate groups of N corresponding picture segments with lens elements of the viewing screen. By means of the device, three-dimensional pictures can be observed without further auxiliary means for the viewer.

Abstract: A data demodulator for digital signals in which the times of the zero crossings in hard limited signals in the orthogonal outputs (I and Q) of a direct demodulation receiver are used to recover the carrier and clock signals.

Abstract: A sensor suitable for measuring magnetic field gradients spanning very small regions has a magnetic field-sensitive element (37, 42) with a very accurately defined height and thickness (even into the nanometer range) which is perpendicular to the surface of a substrate (30, 41) so that the substrate surface may be used in aligning the element (37, 42).

Abstract: An electron multiplier structure comprising an electron multiplier section (11) with one or more microchannel plates and a dynode stage having secondary electron emission. This structure makes it possible to obtain an amplification which is higher than the amplification obtainable with only the electron multiplier section while maintaining the instantaneously obtained characteristics and special resolving power associated therewith.