DE2139292A1 - Infinitely adjustable damping element - Google Patents

Description

Automated Processes, Inc., Farming dale, N.Y./USA

Infinitely adjustable attenuator

The invention relates to continuously adjustable attenuators.

One form of known adjustable attenuator consists of a chain tension divider, at the individual resistors and a multi-position switch to switch back and forth between the different

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Serve attenuation points of the chain tensioning divider. The attenuator consisting of a chain tension divider is not continuously adjustable because it can only provide certain attenuation levels. It furthermore has the disadvantage of being unwieldy and consisting of individual components.

Furthermore, there is an improvement on the former, which consists of a chain tension divider Attenuator known in which a stepless resistance element as part of the chain voltage divider is used to allow a stepless adjustment of the control points of the element. This, also called Sliding resistance known improved form of an attenuator consisting of a chain tension divider allows infinitely variable handling, but like the first-mentioned attenuator, it has the disadvantage of unwieldiness. In addition, the sliding resistor has metallic contacts that are due to surface corrosion are susceptible to noise caused by high frequency rectification. Farther the damping element consisting of a sliding resistor is subject to a certain amount of wear, with resulting loose particles or dust represent a further source of noise when using the attenuator. This can make it necessary to clean such sliding resistors on a daily basis.

The aim of the present invention is therefore to create a continuously adjustable attenuator which avoids the disadvantages of the known attenuators and in particular a simple, compact, over a continuously adjustable attenuator that functions essentially without noise for a longer period of time provides.

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According to the invention, this is achieved in that the following parts are provided: an insulating substrate 30, 55, a layer 31, 52, 63 of resistance material carried by the substrate, one which is in contact with the layer of resistance material and is connected to the input terminal 35, 5δΑ, 68 of the continuously adjustable attenuator connected first electrode 33 * 5 ^ * 64, a second electrode J> h, 55, 65, one on the layer, located at a distance from the first electrode in contact with the layer of resistance material and connected to earth potential A predetermined path of resistive material between the first and second electrodes which is contacted by a sliding contact 17 connected to the output terminal of the adjustable attenuator, and a predetermined path extending from the second electrode in the direction of the first electrode substantially parallel to the predetermined path Arrangement of electrically conductive elements 38 * 56, 66 the layer of resistance material.

The attenuator according to the invention is particularly suitable for audio mixer controls in radio and recording studios use, and several of these attenuators can be combined in one control panel to create a simultaneous Provide attenuation of several sound channels, as is necessary e.g. with stereophonic and quadronic sound systems is.

The arrangement of the electrically conductive elements is preferably such that from the resistance layer

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a smooth logarithmic output is obtained.

Furthermore, the resistance layer on the first electrode can be excluded in such a way that the desired Input resistance is created "while the maximum Current density is maintained at an acceptable level, and certain conductive elements of the arrangement can be in Size and shape of the desired general attenuation characteristic are adapted to v / ground.

Further details of the invention are to be explained and described in more detail with reference to exemplary embodiments be, 'with reference to the attached drawings is taken.

Fig. 1 is a view of the end wall of the attenuator according to the invention with control button and Attenuation scale tick marks,

Fig. 2 is a cross section through the attenuator according to the invention along the lines 2-2 in Fig. 1,

Fig. 5 is a view of the resistance element of FIG Line 2-2 in Fig. 2,

Fig. 4 is a detailed cross-sectional view taken along line 4-4 of Fig. 2 with the moveable Contact arrangement,

Fig. 5 is a perspective view of a cylindrical Shape of the resistance element of a modified continuously adjustable according to the invention Attenuator,

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6 is a development of the FIG cylindrical resistance element of FIG. 5

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Fig. 7 is a detailed view of a planar, generally circular resistive element; also for an attenuator according to the invention.

The drawings are discussed in greater detail below. Fig. 1 shows end wall IO and control button 11 of the continuously variable attenuator according to the invention. The control button 11 is of a Hull damping indicating movable to a position indicating infinite damping. The end wall 10 can be on a larger control panel in a recording studio e.g. by means of screws 12 or other fastening elements in a conventional one Way to be attached.

Fig. 2 is a cross section along line 2-2 in Fig.l through the attenuator according to the invention. On the back of the end wall 10, a box-like component is attached, in which a resistance element 3> O, 3> 1 and a generally designated 17 movable contact is leniently attached. The latter includes a carriage 18 which slides on a pair of guide rods 19 and 20 shown in cross section in FIG. Bearings 21 and 22 are provided so that the carriage 18 slides along guide rods 19 and 20 more easily. The movement of the carriage 18 is controlled by the control button 11 connected to the former by means of a rod 25. A group of electrically conductive sliding contacts 2h attached to the carriage 18 is only connected to the resistance element and takes

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the output signal of the damping element. The contacts 24 are usually made of precious metal to reduce the possibility of deteriorated job performance to keep on a minimuni due to corrosion.

Pig. 3 is a more detailed view of the resistance element, which consists of an insulating substrate on which the layer 31 of resistance material provided with the attenuation characteristics is applied. The substrate 30 can be made from any of various plastics or other insulating materials known to those skilled in the art. z. B-. made of cast epoxy resin, diallyl phthalate, or of a composite construction such as an I- ^ larschicht (registered trademark) connected to a phenol-containing substance. The resistor material 31 can consist of any resistor material known to those skilled in the art, such as an organic plastic containing some conductive material, and should preferably have a low coefficient of fracture and self-lubricating properties in order to reduce wear to the minimum. The material 31 should also have a high stability with respect to time, temperature, humidity and corrosion conditions. It can be applied to the insulating substrate in any suitable manner, such as by spraying, silk screening, coating or the like. The resistance characteristic of the layer of resistive material 51 can be of any suitable value, typically 100 ohms per square element, this value being selected depending on the exact geometry desired and the terminal resistance of the one element.

Two electrodes 33 and Z & are held by the resistive layer, the electrode Tj is the input

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electrode and is at point 35 with the to be damped Signal connected. One electrode 34 is the ground electrode and connected to the ground potential at point 36. An arrangement of conductive parts 38, resistance fields called., extends from the ground electrode 34 in the direction of the input electrode 33

The electrodes 33 and 34 and the conductive areas 38 are preferably silk screened

applied to the resistive layer. It can, however Other methods of depositing the electrodes 33 and 34 and the conductive areas, if necessary 38 can be applied. The electrodes 35 and 34 and conductive regions 38 can be any suitable conductive material such as powdered silver in a plasticizer binder, which, after being applied in a silk sieve process, was brought to harden by heating.

The sliding contacts 24 are by controlling the control button 11 on one at the edge of the resistance layer 31 from input electrode 33 to ground electrode 34 extending path along movable. At the input electrode 33 lingering sliding contacts 24 is that output signal obtained from the latter is almost equal to the input signal inputted to the electrode 33, so that the attenuation obtained is almost zero. If, on the other hand, the sliding contacts 24 are on the ground electrode 34 are located, the output signal obtained from the sliding contacts 24 is very close to the ground potential and causes it hence essentially infinite attenuation.

The sliding contacts 24 advantageously only touch the resistance layer 3I and are carried by the carriage 18 stops at both ends of its path in front of it

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kept touching electrodes 55 and 54 uxh erratic To prevent changes in the impedance of the device and the resulting signal noise.

It is noted that when the control button 11 is fully set to "infinite damping", the sliding contacts 24 enter a recess 41 delimited on three sides by the ground electrode J4. In this way it is ensured that the resistance material in the recess 4l is essentially at ground potential. Furthermore, the ground electrode j4 is connected to the ground potential at point J> 6 , which is located in the vicinity of the entrance to the recess 4l. The arrangement of the connection point 56 at this point reduces the effects of the stray electrical field within the recess 4l on the outermost 'and also ensures that the sliding contacts 24 are essentially at ground potential when the control button 11 is set to infinite attenuation. It is found, however, that because the sliding contacts 24 remain in contact with the resistance layer J> 1 and do not touch the Iiasseelectrode J54, a substantial resistance is maintained between the contacts 24 and the ground even at zero potential. '

The electrically conductive areas or resistive panels 58 serve a number of purposes. More precisely, the resistance fields J> Q extending from the ground electrode 5 ^ in the direction of the input electrode 55 enable the entire resistance layer 51 to behave like a stepless chain voltage divider. Furthermore, the device can be trimmed by the resistive panels 58 so that irregularities in the resistive characteristics of the resistive layer 51 can be balanced out, as will be described in more detail below. With the current state of the art , such irregularities are virtually inevitable in the resistor material.

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To increase the input impedance of the device in the state of least attenuation and in this way To reduce the insertion loss, the resistive layer 31 is cut at the end near the input electrode 33, as shown in Fig. 3 at '' area 4-3 with shown traces of a trimming tool scraping the resistor material from the substrate. By cutting away the resistive layer on the input electrode 33 can have the minimum input impedance of the device can be increased to a nominal value of 300 ohms. After trimming, the resistance material 31 diverges at an angle of about 45 ° from input electrode 33. The cutting out of the resistor material. 31 corresponds to a shortening of the resistance material 31 in the transverse direction at the electrode 33 what because of the risk of a short circuit between Ground electrode 34 and input electrode 33 through the conductive Elements 38 could not be provided in an expedient manner. The resistor material is also trimmed 31, the damping characteristics of the device cut to size for the first 10 db of attenuation. However, the resistance material 3I can also be first in this arrangement can be applied and subsequently trimmed as required.

The exact contour to which the resistive layer 31 is trimmed is made by measuring the actual values of the damping properties of the device close to each other Adjustments of the sliding element and by comparing the measured damping with the nominal value of the device while cutting out the resistor material certainly. Therefore, the exact contour to which the resistive layer 3I is trimmed depends on the above mentioned inevitable irregularities in the properties of the resistor material ©.

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The attenuation characteristics of the remainder of the device can be trimmed to the precise attenuation curve desired by slightly changing the size and shape of the conductive regions 38. This is accomplished by either scraping off small areas of the conductive spots 38 or by enlarging them with a conductive paint which can be made from powdered lacquer-based silver. By starting the work at the end of the low attenuation (near the input electrode 33), changes in the attenuation curve can be made with negligible effect on previous changes. Connections between the ends of the resistance fields 38 or enlargements of the individual resistance fields cause a reduction in the attenuation with all settings of the sliding contact 24 in the direction of the end of higher attenuation (at the ground electrode 34). Connections made between the sides of the resistance fields 38 result in increased damping of the device for all settings of the sliding contact 24 in the direction of the end of the higher damping Attenuation characteristics of the device as equal changes (applied to resistive fields 38 located further away from the path of contacts 24). Connections between the ends of the resistance fields are indicated by dotted areas 45, while connections between the sides of the resistance fields are indicated by dotted areas 47; are.

The track of the contacts 24 is wo.Lt enough from the conductive elements 38, so there is local interference of the field gradient are fully compensated.

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In addition to the fact that they facilitate the trimming of the resistor selenium IG to the desired exact attenuation curve, the elongated resistor fields Jo cause the resistance of the resistor layer 51 in the transverse direction to be greater than in the longitudinal direction (parallel to the tracks of the contacts 24), so that the width of the resistor layer 21 can be small in proportion to its length. Those skilled in the art will admit that the same effect can also be achieved by arranging compact points or points (round or square points or the like) arranged more densely in the longitudinal direction than in the transverse direction.

will be

could be enough. It is also admitted that at least 5 a series of conductive areas, preferably that of the path of the output movable contact air; furthest distant row, by one away from the cash register electrode 54 extending stepless ladder could be replaced.

4 of the drawings shows a cross section through the movable contact according to line 4-4 in Fig, 2. The sliding contacts 24 are in contact r.-dt that of the insulating substrate 50 held V / resistance layer shown. The sliding contacts 24 are ir.it the output electrode 48 through a to collect beryllium copper made flexible to the movements of the carriage IS er-Bc-nd 4 9 connected.

As with the conventional attenuator, a stationary resistance of half the nominal impedance is in series with the moving contact switched to at the end of the Resistance changes occurring on the track to a minimum to keep.

In Figs. 1 to 4, a resistance element is in Shown in the shape of a rectangular stripe, but other shapes can be used. In Fig. 5 of the

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In the drawings, a perspective view of a modified form of a resistance element 51 of the continuously adjustable attenuator according to the invention is shown. The resistance element 51 consists of a layer of resistance material 52 carried by a cylindrical substrate 53. The input electrode 54, the ground electrode 55 and electrically conductive resistance fields 56 are carried by the resistance layer 52. Sliding contacts 57 are such that they are able _f along to move 55 to a path between the input electrode and the ground electrode 5 ^. The line 58 carrying the input signal to the resistive element 5I may extend through the interior of the cylindrical substrate 53 and is connected at point 58A to the input electrode 5h . In the same way, the grounded lead 59 can extend through the interior of the cylindrical substrate 53 and is connected to the ground electrode 59 at point 59A.

Pig. 6 is a detailed development of the Pig cylindrical resistor element 51. 5 «

The cylindrical element 5I according to FIGS. 5 and 6 works in the same way as the right-angled part, but its main advantage is in the lower cost of elements of slightly lower precision. Since the diameter of a cylinder is less than 1/5 of the circumference, can be shortened using conductive elements can be omitted for certain uses. In a simplified embodiment one can run a single grounded conductor along one side of the cylinder and the moving contacts move along the diametrically opposite side. In a further modification, the input and ground electrodes, a ladder attached to the cash register and possibly

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Existing resistance fields can be attached to an insulated core on which the resistance material is applied is. Alternatively, a hollow tube of injection molded plastic resistor material could be placed over the core be drawn and e.g. shrunk by means of heat. Main electrical connections were then made within the Cylinder and additional trimming could be done on the outer surface if necessary.

Fig. 7 is a detailed plan view of a much more modified form of a resistance element for the continuously variable attenuator according to the invention. Those skilled in the art will admit that the resistance element 61 according to FIG. 7 is suitable for use in an attenuator which has a rotatable operating knob instead of the linearly movable operating knob according to FIG. The resistance element 6l has an insulating substrate carrying the resistance layer 63. The input electrode 6k and ground electrode 65 and the electrically conductive elements 66 are supported by the resistance layer 53. According to FIG. 7, the conductive elements 66 have the shape of round points which are arranged more narrowly in the direction of the circumference than in the radial direction.

The sliding contacts 67 are movable on the resistive layer 53 from the input electrode 6 ^l \ to the ground electrode 65 in an arc which may be as shown, are located on the outer portion of the layer 53, or the arrangement may be reversed, with located near the inner periphery of the element extending contact track. The input signal for the resistance element 61 is connected to the input electrode 6k at point 68 and the ground electrode 65 is connected to dei.-i ground potential at point 69.

For those skilled in the art it can be seen that both the resistance element 51 according to Fig. 5 and 6 also the circular one

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Resistance element βΐ according to FIG. 7 to the in connection with your right-angled resistance selenium ent according to Fig. j5 Described desired, precise damping curve can be trimmed / grounded. More precisely, the cushioning can at the end of the low attenuation of the scale can be changed while the input impedance of the device by trimming parts of the resistor material like in areas 50 according to FIGS. 5 and 6 and area όο according to Fig. 7 is maintained. The remaining part of the element can (if necessary) be the one you want Damping curve to be adjusted, indan; the electric

^ conductive resistance fields 56 according to FIGS. 5 and 6 and the resistance fields 66 according to FIG. 7 by means of the elements described in connection with the resistance fields from FIG. 5 Technology trimmed. More precisely., At the beginning of work at the end of lower attenuation of the Resistance element made a series of changes by means of a conductive varnish, which a negligible effect on changes made previously exercise. Connections between the ends of the resistance fields or elements are capable of damping of all points towards the end of higher attenuation of the element, and a connection between the The resistance fields or elements are capable of

ψ to increase damping for all- points towards the end of higher damping of the element.

Having described the present invention in terms of a preferred embodiment and several modifications thereof, it will be apparent to those skilled in the art that certain variations in the shape of the wicler stand element are conceivable in the present invention. For example, the resistance element can be made in the shape of a crescent moon or bou -nu , or it can be a counter-learning element. Type according to FLg, 3 around the surface of a drum gevmnUori no and with a rotating control knob VerwfiKio '". Viorä-jii,

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Like the known attenuator consisting of a chain tension divider v / e is the inventive, Infinitely adjustable attenuator when switching between a line and a load with nominal impedance has an insertion loss of 6 db. It is clear, however, that the attenuator according to the invention can also be used as a regulator in the manner of a potentiometer. When used with high impedance loads v / e the present device is an insertion loss from zero and shows no reduction in accuracy or other puncture properties.

Those skilled in the art will also be familiar with that, as with a known attenuator, the input and output terminals of the present device can be replaced, i.e. the signal can be sent to the movable contact applied and the output of the stationary terminal removed.

Although the principles according to the invention based on an advantageous embodiment and various modifications asymmetrical damping elements have been described, it is obviously that symmetrical attenuating members are also involved Can be easily constructed using the same material and techniques.

Claims;

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Claims (9)

Claims 1.7 Infinitely adjustable attenuator., Characterized in that the following parts are provided: an insulating substrate (JO, 55), a layer (31, 52, 63) of resistance material carried by the substrate, and one in contact with the layer of resistance material ^{first electrode (33 * 5 2} ^ 64) connected to the input terminal (35 »5ÖA, 68) of the continuously adjustable attenuator, a second electrode located at a distance from the first electrode in contact with the layer of resistance material and connected to the earth potential ( 3 ^ ·, 55 * 65), one on the layer of resistor material between the. first and second electrodes extending predetermined path which is contacted by a sliding contact (17) connected to the output terminal of the adjustable attenuator, and an arrangement of electrJsdi extending from the second electrode in the direction of the first electrode substantially parallel to the predetermined path conductive elements (38, 56, 66) on the layer of resistive material. 2. Attenuator according to claim 1, characterized in that the electrically conductive elements (38,56) of conductive elements arranged substantially parallel to the predetermined path of the displaceable contact (17) elongated fields exist. 3. Attenuator according to claim 2, characterized in that the conductive elongated fields (38j 56) in a plurality of rows parallel to the predetermined one Path of the sliding contact (17) are arranged. - 17 109887 / U02 4. Attenuator according to claim 2 or 3, characterized in that the conductive elongated fields (38,56) next to the second electrode (34,55) are longer than the conductive fields next to the first electrode (33,520 ⁾ . 5. Attenuator according to claim I _1, characterized in that the electrically conductive elements consist of punctiform, electrically conductive material fields (66) carried by the conductive layer (63). 6. Attenuator according to claim 5, characterized in that g e that the electrically conductive, punctiform fields (66) parallel to the predetermined Path of the sliding contact (17) are arranged closer than transverse to the predetermined path. 7 »Attenuator according to one of claims 1 to 4, characterized in that part of the second electrode (3 * 0 one the end of the predetermined Forms recess (41) surrounding the web on three sides. 8. Attenuator according to claim J, characterized in that the second electrode (34) is connected to earth potential (36) at a point at the opening of the recess (4l). 9. Attenuator according to one of Claims 1 to 4, thereby characterized in that the resistive layer (31) deviates from the first electrode (33) at an angle of approximately 45 °. - 18 - 109887/1402 • 2139292 -ίδιο. Attenuator according to one of Claims 1 to 4, characterized in that the layer of resistance material (31) is in the shape of an elongated rectangle, the first electrode (33) at one end and the second electrode (3 ^) at the opposite End of the resistive layer is arranged, the predetermined path runs on one side of the layer of resistive material and the arrangement of elongated, electrically conductive elements (38) is on the opposite side of the resistive layer. 109887 / U02 Blank page