FR2544116A1 - Device for tangential reading arm moving over a fluid - Google Patents

Abstract

The invention relates to a device for a tangential reading arm moving over a fluid. It consists of a deck unit 1 equipped with a table 2 to which is fixed a height-adjustable carriage holder 3 and its slide 3a, drilled with orifices 4 used for evacuating the fluid. A carriage 5 set along 3a slides along the latter over an air cushion. The air circulates between the slide and the carriage. The carriage is equipped with a counterweight 7 and an inertia ring 8, a stabilising and damping tip 12 and a cell-holder shell 10. Application to the manufacture of reading arms in the field of hi-fi.

Description

 The present invention relates to a device for tangential tonearm moving on fluid.

 More specifically, it is a tangential tonearm device used in very high fidelity sound reproduction and moving on a fluid and more precisely on an air cushion.

 The displacement of the tangential tonearms requires rigor in the manufacture of these said moving parts. The cost of machining precision parts is becoming more and more expensive.

 Devices are known for carrying out this type of movement; in general, the arm moves tangentially to the groove by a mechanical system: bearings on rails, bearings on quartz bars, etc. All of these techniques bring significant mechanical constraints to the level of the stylus, either due to the friction, either because the servo system does not instantly respond to the need to move the arm, moreover this system ensures the movement of the arm only in the outside-center direction while, due to the eccentricity of many discs, the arm must be able to move in both directions (outside-center and center-outside).

The tangential displacement mode is essential in the high level sound reproduction, because it is the only one to completely eliminate the track error, defect affecting all the pivoting displacement arms despite the angle compensation. offset,
Figure IV.

 The transmission of vibrations from the plate to the reading cell via the mechanical connections of conventional arms: these vibrations picked up by the cell hinder the proper functioning of the latter. This phenomenon cannot occur in the case of an arm on an air cushion because there is no mechanical connection between the arm and the plate.

 The present invention intends to remedy these drawbacks by proposing an improvement to these known machines, by which the conditions of movement of the tonearm and its connections are improved.

 To this end, the subject of the invention is a device for a tangential tonearm moving on a fluid and more particularly on air, constituted by a plate known in its facts but whose originality lies in the displacement of the tonearm .

 One of the main characteristics of the invention is the displacement of the entire tonearm on a fluid avoiding all mechanical friction, and giving no stress at the level of the cell.

 In a preferred embodiment of the invention, is that the cell fixed to the arm simply moves through the moving groove once the tip is placed in the groove of the disc.

 Fixed to the back of the arm, a spatula immersed in a special oil tank, allows the amplitude of the arm's movements to be damped. This in the horizontal direction and in the vertical direction.

The invention will be better understood during the description given below by way of purely indicative and nonlimiting example, which will make it possible to identify the advantages and the secondary characteristics thereof. Reference will be made to the accompanying drawings in which
- - Figure I illustrated by a top view
schematic of a tonearm device
tangential moving on fluid.

 - Figure It is a section along AA '.

- figure III represents a central ellipsoid
of inertia of an arm with symmetrical geometry.

- Figure IV represents the track error of an arm
classic compared to a tangential arm.

 Referring first to Figure I we see from above, a platinum chassis 1 known in its facts, a rigid disc carrier plate 2, a carriage carrier 3 consisting of cavities in which the fluid is passed through the fittings 13 and which then passes through a multitude of nozzles 4. The said carriage holder has a concave or convex shape in which a carriage 5 adjusts and which acts as an arm holder. This said carriage may or may not be in one piece. A stepped and hollow arm 9 is secured to the carriage by a clamping screw or the like 11. A counterweight 7 allows the pressure adjustments of the cell on the disc. An inertia ring 8 makes it possible to bring the center of gravity of the arm as close as possible to its horizontal axis of rotation. A cell holder shell 10 allows the attachment of a cell as well as its orientation in three dimensions.

 An adjustment system 16 allows adjustment of the slide carriage carriage and carriage carriage arm, both in height as well as horizontally, this using the spirit level 17. At the rear of the carriage holder we find a tank 6 filled with special oil to allow the damping of the amplitude of the movements of the arm in the vertical direction and in the horizontal direction.

 FIG. 11 illustrates a preferred embodiment of a tonearm of the device according to the invention as well as the carriage holder 3 which is formed in its lower part by cavities each comprising two orifices 4 and a photoelectric cell 4a. Each cell controlled by a solenoid valve 4b responsible for supplying fluid with one of the connections 13, the cavity to which this solenoid valve belongs. 4 through which the fluid will flow between this said slide and the carriage 5 whose shape can be concave, convex or other. Said trolley can be in one piece or made up of several parts. The two surfaces facing each other must be adjusted relative to each other so as to limit the roughness to obtain an impeccable movement and to require only a minimum flow of fluid. The assembly 3 and 3a formed of watertight boxes, the fluid arrives through the fittings 13 and leaves it through the orifices 4. a tank 6 is fixed to the rear of the carriage holder: a quantity of oil is poured into this tank and has the effect of damping arm vibrations. The monobloc or other carriage 5 is crossed by an arm 9 tu # bular or other at one end there is seen an adjustable counterweight 7, a spatula 12 is inserted in this tubular arm, the latter soaks in the tank 6; on this tubular arm is fixed an inertia ring 8, this is adjustable along the arm, at the end of the arm is fixed a clevis lOb on this clevis is fixed a cell holder shell 10 on which a reading cell 10a comes adapt, the trolley and trolley carrier assembly are mounted on a sole 15 and the height adjustment is carried out using a spacer 14 the whole is fixed on the plate 1.An armrest 16 is provided on the turntable.

 We see that with the device described in the present invention the centers of gravity are aligned and that the movement of the carriage arm on its slide is done on an air cushion eliminating any mechanical connection, any lubrication, and any sticking of dust . The movement of the arm is then carried out under optimal conditions.

 By the simplicity of this process, we see that all the centers of gravity are aligned on the line 'once the adjustment has been made' is parallel to the surface of the disc. The dynamic constraints applied at the tip of the reading are then equal to each other (Figure III).

 The invention finds an interesting application in the manufacture of tonearms in the field of high fidelity sound reproduction.

 It is not limited to the description which has just been given, but on the contrary covers all the variants which could be made to it without departing from its scope or its spirit.

Claims (7)

CLAIM 1 - Device for tangential tonearm moving on fluid and more particularly on air cushion characterized in that it is constituted by an assembly (1) whose mechanism is known in these facts. Said turntable is capped with a disc carrier plate (2). At the rear of the plate is mounted a carriage holder assembly (3) and a carriage (5) equipped with its arm. 2 - Arrangement according to claim 1 characterized in that it is constituted by the carriage holder (3) which is parallel to xx 'and perpendicular to yy' and vice versa and that the entire arm (9) is parallel to yy ' or at xx ', this arm moves perpendicular to the axis of the carriage holder. 3 - Device according to claim 2 characterized in that it is constituted by a carriage holder (3) in the form of cavities in which the fluid passes through the fittings (13). These cavities of the carriage holder, the upper part of which forms a slide, are perforated with a multitude of orifices (4) allowing the fluid to escape, so as to create a cousin of air when the carriage (5) is placed on it. . This system avoids any oily or other lubrication, and any friction. 4 - Arrangement according to claim 3 characterized in that it is constituted by a carriage (5) and a slide (3a) of concave, convex or other shape but allowing movement from bottom to top of the tonearm (9). 5 - Device according to claim 4 characterized in that it is constituted by a carriage (5) directly receiving the stepped arm (9) it is stopped by a fixing screw (11). A counterweight adjustable by micrometric screw (7) used to adjust the force applied to the stylus. a spacer ring (8) makes it possible to adjust the center of gravity of the arm. At the end of the arm a yoke (10 b) receives a cell holder shell (10) which makes it possible to adjust the reading angle using standard or other reading cells.  6 - Device according to claim characterized in that it is constituted by a spatula (12) placed at the rear of the carriage (5) which plunges into a tank (6) containing a fluid (6a) allowing the damping of the arm when moved on the disc. 7 - Device according to claim 6 characterized in that 11 carriage carrier assembly (3 - 3a) and carriage (5) equipped, either parallel to the surface of the plate these are mounted on a plate (15) and adjustable in height by a spacer (14) and a screw (16). A preset is obtained using a spirit level (17).