Analogue signal detector for e.g. joystick - has rectangular resistive panel with known time dependent voltages applied to X and Y coordinates

Holder: Idem ©) (74) Agent: Mediterranean Office of Invention Patents, Hautier office, 24, rue Masséna, 06000 Nice.

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Sale of pamphlets to PRINTING NA TIONALE, 27. rue de la Convention - 75732 PARIS CEDEX 15

The subject of the invention is a device and its method for analog data entry and display of said data.

Currently, data acquisition tables are of the digital type, for example, diode arrays. It is therefore easy to understand the complexity of the wiring. In addition, the table grid cannot be very precise. These tables are therefore very expensive due to the wiring of the diodes.

The invention avoids all these drawbacks.

It makes it possible to manufacture plotters at costs four to five times lower than with the current technique.

The accuracy of the plotter, according to the invention, is very high. The network can be gridded to 1/1000 mm.

The invention uses a surface such as a resistive layer and a filtering means such as synchronous detection.

The device and its method of analog input allow the tracking of a point on a plane by associating two voltages (t) and Vy (t) proportional to the coordinates x (t) and y (t) of said point at the instant £ or varying linearly with these coordinates x (t) and y (t).

This so-called analog table device and its application method are mainly constituted in a preferred version, by a uniform thin resistive layer deposited on a flat surface, of resistance R_t per square. The table or flat surface preferably has a rectangular shape; the angles are noted A, B, C and D.

Points A and B, B and C, C and D, D and A are joined by a resistive wire, or any other resistive system brought into electrical contact with the resistive film of the table; this resistive wire has a resistance R | for AB, R2 for BC, R ^ for CD and R y for DA. If this resistive wire is applied along a circular contour, or as a first parabolic approximation, such as the distances from the midpoint of these wires to the segments AB, BC, CD and DA verify the relations'.

- ^ = Rj/8R_t, &₂ = R₂/ 8R_t...

The mathematical calculation shows that if the following potentials are applied to points A, B, C and D:

* V (A) = 0 * V (B) = V_T (t) * V (C) = V₁ (t) + V₂ (_t)

- 2 2522425 * V (D) = (t) where Vj and ^ 2 are arbitrary functions of time.

The potential of a current point M, of coordinates x and related to the axes AB, AD is:

* V(M,t) = (x/AB) Vj (t) + (y/AD) V₂ (t)

The potentials and V₂ are chosen so as to be periodic with frequencies eu and

In a preferred version, we choose the potentials and V₂as follows :

<img file="FR2522425A1_D0001.tif" />

during one half period during the other half period

In a preferred version, the pot ential V (M) undergoes a so-called synchronous detection with respect to the frequencies and with respect to the potentials applied in B and D. This synchronous detection provides two voltages ν_x and V varying proportionally with the x and χ coordinates of the point M. In fact, one can also use any filtering system leading to the separation of the components at frequencies vJ and eu₂ of the potential V (M, t).

The data visualization device and method provide a permanent visual image of a plot made on a data entry table (for example, the analog table described above).

The data entry device provides information in the form of voltages V_x(ί) and Vy (t).

The invention makes it possible to store this data on a closed magnetic support rotating at low speed, then to restore this data by rotating this closed support at a ne frequency of the order of 15 Hz (cinema frequencies).

Any known operating device associated with the device according to the invention then allows viewing of the initial route. We can cite, for example, an oscilloscope screen, an advertising screen ...

The closed magnetic support can be constituted by a closed magnetic strip, or in a preferred version, by a flexible magnetic disc or not (for example the conventional discs used in computer science).

In a preferred version of the invention, the data relates to the x and y coordinates. are recorded on two different tracks using a double magnetic head or two separate heads.

Still in a preferred version, a coding system is used which eliminates inhomogeneities from the band. The simplest coding system is conventional and consists of a series of pulses, the distance of which depends on the amplitude of the signal to be coded. .

The decoding of this type of pulse is well known and will not be described here.

In a preferred version of the invention, when the device for capturing the potential of the analog table (metallic or conductive tip) is raised, that is to say when the signal to be coded no longer arrives, a device basic electronics to be made allows the recording system to be stopped.

Still in a preferred version, an elementary electronic device accumulates the recording times and stops this recording after one turn of the tape or of the magnetic medium.

These devices are conventional, in the public domain and are not described here.

The attached drawings will easily make it possible to understand the invention. They represent a preferred embodiment according to the invention.

FIG. 1 is a schematic view of a plotter with synchronous detection using a resistive layer uniform thin stive deposited on a flat surface of resistance R per square.

Figure 2 is an electronic diagram and a flow diagram of the functions.

FIG. 3 is a view of the implementation of the method according to the invention, which makes it possible to combine a positioning joystick commonly known as a Joy Stick, or a broomstick positioner and a resistive table.

Figure 4 is a diagram which allows, according to the method to position in volume.

In Figure 1, the four points A, B, C, D are arranged at the four corners.

If the following potentials are applied to points A, B, C and D:

- 4 * V(A) = 0 * V(B) = Vj (t) * V(C) = Vj (t) = V₂ (t) * V (D) = V₂ (t) the potential of a current point M, of coordinates x and y_ related to the axes AB, AD is:

* V(M,t) = (x/AB) Vj (t) + (y/AD) V₂ (t)

In a preferred version, the potential V (M) undergoes a d so-called synchronous detection with respect to frequencies j and ^₂ or compared to the potentials applied in B and D. This synchronous detection provides two voltages V * and V varying proportionally with the coordinates x and χ of the point M. In fact, one can also use any filtering system leading to the separation of the components at the frequencies uv j and tu of the potential V (M, t).

A resistive film deposited on said table 2 in which, in a preferred version, the device for applying the potential is produced by means of a resistive linear element brought into contact with the table 2. Said film is a graphite placed on an insulating support . The resistivity can be, depending on the applications, of the order of 2000 ohms per square. This product is a resist film produced by the company SFERNICE in Nice, in France.

According to a variant, the resistive element 5 is arranged along a parabolic or circular contour for each segment such as the top of the parabola (or from the circle) is at a distance i) from the resistance resistance

D of the recsegment considered such that ô = Rj / (8R), where R is the square of the resistive film covering the table and Rj the total of the resistive excitation element.

The tensions applied to the vertices A, B, C and tangle constituting the table are such that:

* Va = ^vO * ^VB = ^VO * ^V1 <«’ ‘ W’i <*> ^{+ V}2 ^(tl * ^VD - ^VO ^{+ V}2 ^(t)·

A device combined with the table is combined to act as filtering 4 and 6 around the frequencies.

a means 1 ^and 2 intended to obtain voltages varying independently with the coordinates of a point on the table whose potential is analyzed. The filtering means consists of a detection on synchrone.

- 5 2522425

FIG. 2 represents the electronic diagram of the device and the flow diagram of the functions.

The resistive table 2 coated with its uniform thin resistive layer is electrically connected to its four corners A, B, C D. These points A, B, C, D are connected to an oscillator 7 or clock x and to an oscillator 8 or clock y, each corresponding to the XY coordinates of a point on the table 2. These oscillators are optionally linked together by means of synchronization and phase shift 9. In parallel, connected to one of the corners of the table 2, an adder is connected 10.

The information collected goes to two logical gates 11 and 12; filtering and shaping means 4 and 6 make it possible to obtain the signals x and y which can be reproduced for example on an oscilloscope, not shown.

Finally, in FIG. 3, a positioning lever 13 is mounted on cardan shafts or a suspension with ball joints 14, on a a resistive table 2. The tip 15 of this positioning lever or Joy Stick comprises a support spring, not shown, which comes into contact with the resistive layer 5. The outer box 16 is shown in dotted lines. The outputs and inputs 17 correspond to the power supply and to the outputs of the signals x and y.

It is easy to understand the advantage of this application which currently exists by using, at the level of the cardan or ball joints, at least two potentiometers with a set of gears. This mechanism is expensive to manufacture, assemble and moreover is not reliable.

On the other hand, the invention lowers the cost of this application since there is no mechanics, and makes it possible to obtain a very fine positioning with this lever 13.

In Figure 4, three oscillators or clocks are needed.

<td>saires. We consider the cube</td><td>A,</td><td>B, C, D, A ', B', C, D 'and the</td>

<td colspan="3">sign to S., 83, S „oscillators. The signals to be applied are</td>

<td>shown schematically in Figure 2.</td><td></td><td></td>

<td>A : 0</td><td>A'</td><td>^{: S}3</td>

<td>B : S₁</td><td>B'</td><td>^{: S}1 ^{+ S}3</td>

<td>C ^{: s}i ^{+ S}2</td><td>C'</td><td>: Sj + S₂ + Sg</td>

<td>D : S₂</td><td>D'</td><td> ' ^S2 ^{+ S}3</td>

- 6 2522425

The signal collected at a point in the fluid will be xS ^ + yS₂zSg, the coordinates x "X" £> being obtained by synchronous detection and filtering described above.

- Ί 2522425