DE7243122U - BUTTON SWITCH FOR A MUSICAL INSTRUMENT - Google Patents

Description

till · ·

Patent authority

· Dr. schmidt Hermann- Hermann "mONCHEN 2 · Theresien.tr.»

23, I ^ ν,

MATTEL, INC.

Hawthorne, California Roseorans Avenue 5150 V. St. A.

Key switch for a musical instrument.

The present invention relates to electric musical instruments.

A typical electronic organ contains a number of signal sources, a high-powered amplifier and a keyboard which can be operated by an organ player, which selectively connects the individual signal sources to the amplifier. that the key switches generate, even if this is very small, amplified together with the sound signals, t; o that it is noticeable in the signal output of the organ. Noise generated by switches has various causes. One cause is that electrical ones open and close too quickly Contacts in which short-term current discharges can occur which ^{generate a noise 11} LxJLwIlCnAOS ^11. To prevent this, an elastic resistance contact element can be used

that enables a gradual contact closure. The contacting area has to be for a small amount Movement of the pressed key rapidly increase in area when the contact resistance rapidly drops to a low value should fall off. If a flat pair of contacts is used, one contact being an elastic resistance element is that when it comes into contact with the other contact, it deforms the contact area only gradually increases as the key is pressed. In addition, elastic material tends to if it is deformed, it tends to stick and then suddenly slide on, so that the contact surface gradually grows, thereby generating noise.

Another cause of the little house that occurs with key switches is the ingestion of scattered signals. · This can be reduced to a minimum by placing a grounded conductive plate next to the switch, which shields it against stray signals. If, however, the movable switch element is mechanically relative to this grounded plate vibrates and if there is a potential difference between the two, the variable capacitance generates microphone noise, which can be heard in the organ signal output.

According to one embodiment of the present invention an organ keyboard is provided, the signal sources aο with aineia amplifier connects that noise as possible is kept small. The keyboard contains an insulator plate that carries a series of cylindrical wires; about the Wires extend a spacer strip of insulating material which includes windows leading to the wires. A Construction of superimposed elastic strips runs on top of the spacer strip and can be pushed down through the window in the spacer strip, so that it touches the cylindrical wires. The strip structure consists of a lower and an upper strip

elastic and electrically conductive material through a central strip made of elastic, non-conductive material are insulated from one another. If one down directed force acts on the upper strip, part of the strip structure is deflected so that the lower Strip extends through a window in the spacer strip and makes contact with one of the wires. Such a downward force is generated by the person striking a key Organ player, whereby a leaf spring is increasingly pressed down on the upper strip. The leaf spring pushes the lower strip progressively to the cylindrical wire. This results in a progressively growing contact area between the lower strip and the cylindrical wire.

Each wire is connected to one of the signal sources and the lower conductive strip of the strip structure leads to the input of a high power amplifier. By the progrosä: "- Depressing the lower conductive strip on a Dr oV, the contact resistance is gradually reduced, which keeps noise to a minimum. The curvature of the round wire ^{4 ;? Ensures} that on a small area of the wire with the strip reliable contact is made so that opening and closing of the microscopic contact points is minimized as the force is exerted on the strip. Both the elastic strip and the wire are coated with a conductive lubricant so that the elastic strip opens smoothly the round wire and does not stick repeatedly and slip further, which would cause noise. Each signal source has an earth potential terminal, and the upper conductive strip of the strip structure is also earthed. The upper conductive strip shields the lower strip from stray currents and lower strip through an intermediate one

-4-

Isolation strips are firmly connected to each other, they can do not oscillate relative to one another, so that this noise source is also switched off

There now follows a friction of the invention on the basis of FIG Drawings.

FIG. 1 is a partial view, shown in detail, of an organ according to the present invention with the subject matter shown electrical circuit design.

Figure 2 is a partial schematic view of the keyboard assembly the organ from Figure 1.

FIG. 3 shows a section through the keyboard from FIG.

FIG. 4 is an enlarged partial view of the device of FIG.

Figure 5 is an enlarged fragmentary view taken along line 5-5 of Figure 4 showing the wire with the lower strut. * ·

Figure 6 is a diagrammatic partial view of the arrangement of Figure 5.

FIG. 7 is a plan view of the arrangement from FIG.

FIGS. 8 and 9 show, greatly enlarged, the wire and the lower strip from FIG. 5 and explain the type and Way in which contact is made.

Figure 10 is a fragmentary perspective view of a portion for organ chords according to the present invention.

FIG. 1 shows an organ with several signal sources 10, 12 which can be connected to an amplifier 18, the output of which leads to a loudspeaker 20, via switch sections 14, 16 of a keyboard. The signal sources 10, 12 generate a tone ™ or other very low voltage signal which is amplified in the amplifier 18 to such an extent that

-5-

that any noise generated at the switch sections 14 »16 would also be increased considerably. The switch assembly is constructed in such a way that both a upon bottom closing of the switch sections occurring noise as well as a noise caused by electrical stray currents can be kept minimally small.

The switch assembly includes a series of cylindrical electrical rods or wires such as wires 22, 24 associated with tone generators 10 _; 12 are connected. A contact strip 26 made of highly elastic and partially electrically conductive material is located above the row of wires 22, 24 and is connected to the input of the amplifier 18 via an electrical line 28. If the contact strip is deflected downwards and touches one of the wires, as shown for wire, signals from the tone generator 10 can run via the wire 22 and via the contact strip 26 to the amplifier 18, where they are amplified and fed to the loudspeaker 21. The series of wires 22, 24 are supported by a support board 28 'of insulating material. The contact strip 26 is normally at a certain distance from the wires by a spacer strip 30; the spacing strip 30 contains windows 32 through which the contact strip 26 can be partially bent down. This bending down of the contact strip takes place when an organ player depresses a key 34 with his pinger.

The contact strip 26 is part of a layered structure 36, which has a shielding protective strip 38 made of elastic and electrically conductive material and a central strip 40 of resilient, non-conductive material Insulator strip 40 is firmly connected at its surfaces to the two conductive strips 26, 28, so that all parts of the layer structure are pressed down together »The Protective strip 38 is via a conductor 42 to ground potential

-6-

connected and shields the contact strip 26 against electrical Stray currents a "b.

As FIGS. 3 and 4 show, each key 34 is rotatably mounted on a rotating rod 43 which rests on the support board 28 '. A leaf spring 45 is attached to the button 34 with its rear end. Your front end is near the bottom biased against the protective strip 38. The protective strip is attached to a fitting strip. The front end of the spring usually rests on the part of the protective strip that lies on the passport strip. When the organ player depresses the front end 34F of the key, he stretches the spring increasingly against the protective strip, so that the contact strip 26 is equally increasingly on the wire 22 presses. After a complete downward movement of the Button, the spring can assume the position shown at 45A, while the contact strip is in position 26A the wire 22 is pressed.

When the contact strip 26 is pressed down and one Establishes first contact with the wire 22, the contact area between the strip and the wire is only very small. Of the Strip 26 is made of a moderately high resistance material, or in other words, it is only partial conductive, so that a small contact area results in a high contact resistance. When the strip 26 continues is bent downward, it is deformed on the surface of the wire so that a larger area of the contact strip eus touches the wire, which results in a relatively small contact resistance. The high initial Contact resistance largely switches off the "popping" noise that can occur when between two elements that can be at different potentials, suddenly a contact with low contact resistance

-7-

will be produced. The fact that the contact area "at only slight additional deformation of the contact tire 26 grows rapidly, causes the low-resistance contact is established very quickly so that maximum signal voltage can flow from the signal source to the amplifier. If the Organ player depresses a key 34 with sufficient force so quickly that the contact strip 26 touches a wire 22, the force applied is generally sufficient to quickly achieve the required low resistance in the switch to manufacture

FIG. 6 shows the process in which the contact strip is gradually unrolled or placed on the wire 22. Point 51 forms a first contact; further contact points along the wire follow, for example point 53 · these Points all lie essentially on the top of the wire along the imaginary line 55. The contact area around the Starting point 51 grows around when the on this toilet des The pressure exerted by the Kentaktstrip increases and the stripe deformed over the round wire. The contact surface that exists when the button is almost completely depressed is through the wedge-shaped hatched area 57 is shown in FIG. Such a wedge-shaped surface is created as a permanent one Impression in the strip 26 after prolonged use, the contact area increases along the wire 22 as the contact strip is progressively depressed; at the same time the contact area increases along the width of the wire as the contact strip is slightly deformed by the higher pressure in the vicinity of the first contact point 51. In the vicinity of the Original contact point 51 there is only a moderate increase in pressure, so the rubber-like material of the contact tire not "squashed", which would shorten its lifespan considerably through frequent use.

Bs has sloh found that when using a wire tea 22 or another contact element old rounded surface less rhombus is generated than with an element with a flat surface. It is believed to be the cause instead lies in a reduction in the microscopic contact points. Figures 8 and 9 show the state as is assumed, nah- ?, the original point of contact 51 prevails. The lower surface of the contact strip 26 is not flat but slightly wavy and changes shape when the contact pressure changes. Figure 8 shows the strip 26 at the moment of first contact with wire 22 at point 51. When wire 22 has a flat surface the first contact point could instead be, for example, point 61, which is lower than point 51 (indicated by the imaginary horizontal line 59 »which runs through point 51). Figure 9 shows the strip 26 when a stronger downward force acts on it, locally twisting or deforming the strip can. If the wire 22 were to have a flat surface, this rotation and deformation of the Strip the point 61 from the flat surface, so that another, lower-lying point 63 make contact would. Such opening and closing of contact points causes houses.

In the case of the round rotation 22, only the contact area around the first contact point 51 is increased by increasing the pressure, because of slight changes in direction and shape of the contact strip 26 are not sufficient to bring points 61 and 63 into contact with the wire. Once a certain one Surface area around the point 51 is contact, the contact resistance is oo low that an open and Closing the microscopic contact points has no effect. So the round wire is believed to produce

-9-

22 less noise, as it ensures an increase in the contact area around the original contact point. The strip 26 must of course not slide along the wire 22 after a first contact. I'm going to do that prevent, the strip 26 is firmly connected to the elastic protective strip 38. Regardless of the details During the process of making a first contact, it was found that a round wire has less noise evokes. It should be noted that the elongate contact area (the area which contacts strip 26) of the Wire 22 is convex only in the transverse direction, ie perpendicular to the length of the wire.

As already mentioned, the contact strip also spreads laterally over the wire 22 when the pressure is applied to the Stripe at the point of contact with the wire increases; The elastic material of the contact strip 26 can have a have a relatively high coefficient of friction, so that there is a risk that the material will repeatedly adhere and tear off, as it spreads on the wire. This rapid sticking and sliding can cause significant noise. In order to eliminate this source of noise as far as possible, a conductive lubricant-J1, denoted by 4δ and 50 in FIG. 5, is used is, on the surface of the wire 22 and the lower surface of the contact strip 2 € used for the Contact strips 26 are a number of materials, such as silicone rubber, those with carbon particles is permeated, and as lubricants 48, 50 can be extremely finely powdered graphite can be used.

The shielding effect of the earthed protective strip 38 could also be achieved by a simple electrically conductive plate, which is rigidly attached to the organ near the contact strip 26 would be attached. When the contact strip 26

Λ r Λ

-10-

however vibrates, these vibrations could generate a signal that would be suggested to the amplifier 18. Such a signal would be caused by the contact strip 26 normally at a voltage above ground potential, namely when those generated by the signal sources 10, 12 Sound signals contain glacial current components. A signal source from a photocell, through an optical Scanning light passing through a light track is, for example, such a signal source. In one with these signal sources equipped organ, the contact strip 26 would quickly assume the mean DC voltage potential that the Sigjialquelle generated, this potential by a Coupling capacitor 51 would be maintained. In the case of the present keyboard arrangement, such vibrations induced noise does not occur because of the contact strip 26 and the protective strip 38 with one another "connect are and cannot move relative to each other., The Insulator strip 40 is with its two surfaces on the Strips 26 and 38 attached, thereby preventing eixie relative movement of the two outer strips. The insulating strip 40 can consist of guonated insulating tape, da3 normally used for wrapping wire, but it sticks to both surfaces. The protective strip 38 can like the contact strip 26 are made of silicone rubber with embedded carbon particles. The spacer strip 30, which is provided with the windows 32 through which the Contact strips 26 can reach through, for example made of insulating paper or a number of other materials. The use of windows in a single Strips facilitate the construction of the holder arrangement. the The layered strip assembly 36 can be held over the spacer strip 30 in tension.

The switch construction can be used for various key arrangements. Figure 10 shows a part

-11-

a switch assembly with button-like buttons 70, like them for example, can be used for the section of an organ serving as a chord accompaniment. Any key or each button 70 is slidably mounted in two plates 72, 74 and rests on a tongue 76 which consists of a plate 78 Leaf spring material is formed. A ground strip 80 carries a narrow insulator strip 82 and a narrow one Contact strip 84 · Individual areas of the contact strip 84 may pass through windows 86 in a spacer strip 88 and contact wire rods 90. The ladder are mounted on a switchboard, on which there are conductor strips that connect the wires to the signal sources .

The invention thus provides a switch arrangement which is economical to manufacture and which has minimal noise small that occurs in an organ that has low output power sources. A contact noise is kept minimally small in that wires 22, 24 made of a solid material, such as brass, are used, the one convex surface to accommodate a deformable contact strip 26 have. The contact strip 26 is made of a highly elastic material that is much easier to deform leaves as the material of the wires 22, 24; this increases the contact area between the strips 26 and the Wires, when both are progressively pressed together, continuously, which keeps noise minimally small. By a conductive lubricant on the wire and the Contact strip minimizes the jerky sticking and sliding that occurs when the material moves spreading the contact strip on the wire; in this way this noise source is also kept minimally small. The contact strip is shielded from stray currents by a protective strip 38, which is also made of elastic

/ If si *

Material consists and has an interlayer insulator is connected to the contact strip. The protective and contact strips cannot oscillate relative to one another, see above that a microphone noise is kept minimally small. Of course, the insulating and protective strips can consist of thin films instead of thick layers.

Although particular embodiments of the invention have been shown and described above, it will be apparent that changes and modifications can be made insofar as they fall within the scope of the invention.

Claims (3)

Expectations 1. Switch device for an electronic musical instrument, characterized by a support plate (28 ^f ); an electrically conductive contact element (22, 24) mounted on this plate and having a contact surface which is directed outwardly away from the support plate; a contact strip (36) made of at least partially electrically conductive, easily stretchable and deformable elastic material; Devices (30) for supporting the contact strip, so that the conductive material is kept at a certain distance from the mentioned contact surface, but can be pressed against it; and manually operated devices (34) which serve to press the contact strip against the contact surface by deforming the strip. 2. Switch device according to claim 1, characterized in that the contact surface is convex and the contact strip is held taut. 3. Switch device according to claim 1, characterized in that the contact strip has a strip structure (36) from one first strip (26) made of elastic and at least partially conductive material, a second strip (40) 724? 122 2t. 5.73 elastic, non-conductive material, the surface on the surface of the first Ötreifen rests, and a third strip (38) consists of elastic and at least partially conductive material, the surface on surface at the two-tone The strip rests against the surface of the second strip which is directed away from the first strip, wherein the opposite surfaces of the second strip are connected to the first and third strips to to keep these two strips at a constant distance? the manually operated devices being other V devices (45) which can be selectively pressed against the third strip, thus the first strip is deflected towards the contact element. alquelle (10, 12) with first and second connection - * ^ · Jt clamp; vbis ^ instructions for coupling the second connection terminal the Signajhjtt ^ lle with the contact element (22, 24); an amplifier (18) T * ^ e ^ directions for coupling the amplifier input with the first strip (26) of the strip structure; ur-d devices which eleicte ^ isch with the first Signal source connector and the red strip (38) of the strip assembly are coupled to terminal opposite the third strip Switch device according to claim 3> characterized in that that the elastic material from which the first strip is made is more easily deformable than the material of the Contact element ► Switch device according to Claim 3, characterized by a film of an electrically conductive lubricant. (48, 50), which is at least on that section dos first Strip "is located, which is pressed against the contact element alternating sliding and sticking of the contact strip when spreading on the contact element is kept minimally small. ψ · switch device according to claim 1, characterized by a film auo an electrically conductive lubricant (50), which is located at least on said contact surface of the conductive contact member, whereby alternately sliding and sticking of the contact strip on the conductive contact member when pressing the strip to the element is kept minimally small. Switch device according to Claim 1, characterized in that the contact surface is essentially only in one Plane is convex; wherein the manually operated device the contact strip progressively onto the contact surface of the conductive element without mutual sliding movement is applied so that the strip progressively engages the element along the contact surface as the pressure at the point the makes a first contact, progressively increases, whereby a substantially wedge-shaped contact area between the contact area and the strip is built up. Switch device according to Claim 1, characterized in that the device to be operated by hand is rotatable contains stored key (34) and a leaf spring (45), the first end of which is attached to the key and the two end biased against the support plate (28) iot, wherein a central portion of the leaf spring extends on that side of the contact strip from the elongated contact surface of the conductive contact element is directed away, and wherein this central portion of the leaf spring is attached so that it is to the Fontaktstrip can be stretched progressively flat when the button is depressed. y switch device according to claim 1, characterized in that that several of these Zontaktelemente are mounted on the support plate and arranged in a Reilie; where "at a Spacer strip (30) made of insulating material is attached so that it extends over the row of contact elements, the spacer strip including windows (32) opposite each contact element; and wherein the contact strip is narrower than the window width, so that portions of the contact strip deformed through the window and with the conductive contact elements are brought into contact can; and wherein the hand-operated device passes these portions of the contact strip through the windows selectively deformed therethrough. Switch device according to Claim 10, characterized in that the conductive contact elements are cylindrical in shape Have rods and are made of a material that is stronger than the material of the second strip.