Abstract: A process and device for focussing a light energy beam on a data carrier comprising sites fromed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas of the measurements are stored. The focussing error signal is obtained by filtering these measurements.

Abstract: Assembly component (56) for a disc brake of the type incorporating a calliper (10) sliding on a fixed support (16) by way of two axial pillars (12, 14) each incorporating, firstly, a cylindrical sleeve (42), and secondly, a removable portion (40) one end of which (48) incorporates a thread which is capable of fixing the pillar (12, 14) to the fixed support (16), and whose other end (52) is capable of being pushed in rotation by a suitable mounting tool. The assembly component (56) forms a channel with parallel sides, one side of which incorporates locking portions cooperating with each of the sleeves (42) and firmly fixing the assembly component (56) to the sleeves (42), whose other side carries tapped components (50) capable of cooperating with the removable portion (40), and whose central portion (76) straddles the fixed support (16).

Abstract: The subject of the invention is a disk brake with automatic adjustment of the type incorporating a sliding calliper (10), a brake actuator (12) acting directly upon a first friction component (14) and, by reaction through the calliper (10), upon a second friction component (16), the brake actuator (12) incorporating a mechanical control (32) acting upon a hydraulic control piston (20) through an automatic adjustment device. The automatic adjustment device consists of a screw and nut system (46-60) of reversible pitch which is capable of being actuated by the hydraulic piston (20) beyond a predetermined travel of the latter, the adjustment device incorporating an annular component (76), firmly fixed in rotation to the nut and co-operating with a control piston (64), immobilizing the annular component (76) in rotation when the hydraulic pressure acting upon the hydraulic control piston (20) reaches a predetermined value.

Abstract: The device according to the invention realize the following steps:(a) recording of binary test words on an optical disc associated to distinct engraving optical powers and comprising monotonous series of "1" and "0" logic bits of equal duration;(b) reading of these words;(c) measurement of the durations of these bits in the "1" state and bits in the "0" state,(d) determination of the optical power for which this ratio is closest to one;(d) elaboration and putting in memory of a control signal allowing to obtain this power.In a preferred variant, several test words are recorded and an interpolation is carried out between the measurements.

Abstract: The spring (14), consisting of a metal sheet folded in the general shape of a V, incorporates a pair of main wings (15) bearing against an inside surface of the arch (7) of the sliding caliper (4) of the brake, joined by a central axial portion (16) bearing against the pads (2a, 2b), and at least one mounting wing (21), close to an axial end (18) of the spring, separated from the adjacent main wing (15) by a notch (20) and extended into an end portion forming a hook (22) engaged in an opening (25) in the arch (7) which is provided with a recessed shoulder (27) for retaining the hook (22), the axial end (18) of the spring (14), consisting advantageously of a finger folded back (24), bearing against an inside surface (11) of the inner portion (5) of the caliper which encloses a brake actuator (10).

Abstract: Process for the regeneration of synchronizing signals used for writing and/or reading recorded digital data or for recording on an optical data carrier, wherein the synchronizing signals are regenerated in phase by determining the phase shift of the center of specific pulses with respect to a clock signal. According to a preferred variant, the specific data and the useful information data are coded by a N.R.Z.-type code, the specific data being associated with pulse durations not used in the N.R.Z. code for recording information data. The specific data can be recorded in time multiplexing with digital information data or, according to a preferred variant, in the form of flags at regularly spaced locations on the tracks which define between them zones intended for the recording of data blocks. The recording of these flags can take place prior to any recording of digital information data in preetched form.

Abstract: Process for generating synchronizing signals used for writing and/or reading recorded digital data or recording on an optical data carrier, in which the synchronizing signals are obtained from basic clock signals regenerated in phase with the aid of the determination of the phase shift of a specific pulse relative to the clock signal. According to a preferred variant, the specific data and the useful information data are coded according to the NRZ code. The specific data are associated with pulse times not used in the NRZ code for the recording of the information data. The synchronizing signals generated on the basis of the reading of these flags can then be used for writing during the information data recording phases.

Abstract: The lining support plate (11) incoporates a widened lug part (16) which prolongs a neck part (15) round which is arranged the end loop (31) of the wire spring (30), of which the end of the strand portion (32) opposite the loop (32) has at least one transverse bent part (37) intended to be received in a central through-orifice (22) in the plate (11).

Abstract: The process makes it possible to generate on the basis of discrete preetching elements or flags, the radial tracking error and/or focusing error signals. The flags comprise portions displaced with respect to the mean axis of the tracks to be followed. According to a first variant, each track comprises portions displaced on either side of the axis. According to a second variant the flags comprise portions alternately displaced to one and then the other side thereof. In response to the passages of these portions, windows are generated and the pulses supplied by the photodetectors of the interaction of these portions on the focused scan beam are compared between successive windows.

Abstract: A process and device for focussing a light energy beam on a data carrier comprising sites formed of virgin areas free from any data recording provided along tracks and serving as reference plane for said focussing. In a preferred variation, these areas are preceded by flags associated with a specific code. Control is achieved by measuring the deviation between the plane of focussing of a beam into a spot scanning the tracks and the reference plane formed by the surface of the virgin areas. Between two passages of these areas the measurements are stored. The focussing error signal is obtained by filtering these measurements.

Abstract: A disc brake comprises a torque-supporting member (10) with which is associated an actuating mechanism (28) to stress at least one friction element (22) against a rotating disc (18), this element (22) comprising a lining-holding plate (38) on which a friction lining is mounted. The plate (38) interacts so as to be anchored and to slide with guide surfaces formed on the torque support (10), and an anti-noise spring (48) interacts with the friction element (22) and with the torque support (10). According to the invention, the lining-holding plate (38) has an assembly aperture (46) for the anit-noise spring (48) and this aperture has a bearing portion and a widened assembly portion which opens into the bearing portion and onto one edge of the lining-holding plate (38). The anti-noise spring (48) interacts with at least one part of the bearing portion so as to stress the friction element (22).

Abstract: The angular velocity of an information element contained in the precut track of an information carrier disk is controlled by means of a concentric circular ring located internally with respect to the precut track and constituted by mark zones uniformly spaced in angular sectors. A light beam is projected onto the circular ring and the emergent beam is modulated as a function of the mark zones and blank zones which form the circular ring. Errors arising from eccentric displacement of the track can thus be corrected and the rate of travel of information can be controlled in relation to the reading or recording light beam.

Abstract: The invention relates to devices for optically transcribing in a track carried by a support medium data to be written in or read out. The invention provides a pre-engraved track follower device for a transcription device in which a loop for radial control of the reading spot scanning the track is provided with sampling means taking samples during scanning of nonpost-engraved parts of a pre-engraved track, said scanning corresponding to a data write or read phase. The invention applies more particularly for digital data transcription devices using a single spot for locating a pre-engraved track and since optically writing data therein.

Abstract: The subject of the invention is a disc brake including a movable assembly. The brake includes a movable assembly (10) mounted to slide by two small columns (12, 14) on a fixed support (16). The small columns include a cylindrical sleeve and a screw. A locking element (66) is interposed between the sleeves and the heads (62) of the corresponding screws. The locking element has two forks (70) each engaging in a groove formed in each of the sleeves and also a resilient portion (74) which locks the locking element (66) onto said sleeves by interference with a portion of said sleeves located between said groove and the corresponding end of the sleeve, so as to make the locking element (66) completely secure and prevent rotation of the sleeves when the screws are screwed in. The brake may be utilized for the braking of motor vehicles.

Abstract: The subject of the invention is a disc brake pad and a brake including such a pad.The disc brake pad (10) comprises two opposite sides (16, 18) including projections (24, 26) in which notches (28, 30) are formed, formed by a first part (32) and a second part (34) forming an acute angle (A) between them. The profile of the opposite sides (16, 18) is such that, for any point (P) of the second part (34), the distance between said point (P) and any part of the opposite side (16, 18), except the region of the notch (28, 30), is greater than a value (R) corresponding to the distance separating the apices of said two notches (28, 30) plus a predetermined value. The required profile of the sides is obtained by means of a portion (44) connecting said second part (34) and the corresponding side (16, 18) of the pad (10). Application to motor vehicle braking.

Abstract: A disc brake which comprises a torque absorbing member associated with operating means capable of urging at least one friction member onto a brake disc. The friction member cooperates with the circumferentially spaced edges of an aperture formed in the torque absorbing member by way of one guide key. The key comprises at least one recess permitting radial extraction of the friction member through the aperture when the friction member is situated opposite the recess. The key is capable of occupying an operative position, in which the recess is offset relative to the friction member, and a removal position in which the recess is opposite the friction member. The cross-section of the key forms a V of which the inside face cooperates with the corresponding edge of the aperture and the outside faces slidably receive the friction member. One arm of the V defined by the key extends towards the brake interior whereas the other arm is substantially perpendicular to the radial plane of symmetry of the brake.

Abstract: In a disc brake in which a movable member is slidably mounted on a fixed support member by means of at least one column at least one protecting device is associated to each column to prevent various particles such as mud, grease, etc. to be deposited on the sliding surfaces of the column. The protecting device includes a seal of resilient material which cooperates with the outside surface of the column by means of at least one lip, and which carries a rigid scraper element level with the outside surface of the column. The scraper element is mounted outside with respect to the lip of the seal to clean off the particles of solid materials in a first stage, the liquid particles being retained by the lip in a second stage.

Abstract: A disc brake of the type comprising a torque-taking member associated with an actuator is adapted to urge at least one friction element against a rotary disc. The friction element comprises a backing plate carrying a friction lining and anchors by its backing plate against guiding surfaces formed on the torque-taking member. An anti-noise spring cooperating with the friction element and with the torque member comprises a lock fixing the anti-noise spring axially with respect to the backing plate. A first portion of the spring traverses an aperture formed in the backing plate and cooperates with a second portion of the spring in such a way that the spring forms with the friction element a subassembly removable as a unit from the remainder of the brake.