JPH0145169B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a clad contact (hereinafter referred to as a ``clad contact'') used in an electronic musical instrument. As shown in FIG. 1, the contacts for electronic musical instruments include a movable contact 3 in which a movable contact 2a or a fixed contact 2b is attached to base materials 1a and 1b having spring properties, and a fixed contact 4 on a substrate 5 made of Bakelite or the like. It is used in a fixed position. The characteristics required of the movable and fixed contacts used in this case are low and stable contact resistance, no discoloration or corrosion in any environment, excellent wear resistance, and changing contact. These include always having stable contact properties against pressure. Conventionally, in order to satisfy these requirements, contacts 6 made of precious metal or its alloy material in a solid state as shown in FIG. 2A, or a surface layer made of precious metal or its alloy material as shown in FIG. A so-called clad wire contact 9 is provided as 7 and has a core material 8 made of a base metal or its alloy material.Furthermore, for the fixed contact 2b, a surface layer 10 of a noble metal or its alloy material as shown in FIG. 3A is provided. , a clad contact 12 with a substantially convex cross-section, whose base material 11 is made of a base metal or a base metal alloy material, has been used. However, among the contacts mentioned above, contacts 6 and 9 shown in Figures 2A and 2B are expensive due to the use of expensive precious metal materials in addition to the parts that are actually used as contact parts. In addition, the contact part when welding to the base metals 1a and 1b is also a precious metal material, and depending on the quality of the precious metal material, weldability with the base metals 1a and 1b is poor, and the cross section is Due to the circular shape, the welding area with the base metals 1a and 1b is small and stable welding strength cannot be obtained, which is a drawback. Although the clad contact 12 shown in FIG. 3A does not have this drawback, it does have the drawback of causing subtle changes in the tone of the electronic musical instrument when used for a long time. It has been found that this is because the contact resistance varies depending on the contact position between the movable contact 2a and the fixed contact 2b when used for a long time. The cause of this variation in contact resistance is not clear, but as shown in FIG. 3B, the oblique sides 13a, 13b, 13c of the cross-sectional shape are not connected in a straight line, and depressions 14a, 14b are generated. This seems to be because the heat generated in the depressions 14a and 14b becomes discontinuously diffused. The present invention has been made with attention to this point, and aims to provide a clad contact that eliminates the above-mentioned drawbacks while satisfying the characteristics required for a contact for an electronic musical instrument. is a clad contact made by welding a contact metal to the top of a base metal, the cross section of the overall shape is an isosceles triangle, and the contact metal is placed in a corner sandwiched between the two sides of the isosceles with the outer surface being straight. The top surface of the contact metal is formed in a rounded shape, and the angle of one corner sandwiched between the two sides of the isosceles is 65° ~ 65°.
It consists in a clad contact characterized by a range of 115°. Next, an embodiment of the present invention will be described with reference to FIGS. 4 and 5. In the figure, reference numeral 17 indicates a clad contact according to the present invention, and this clad contact 17 has a contact metal 15 provided on the top of a base metal 16.
6 is made of a base metal or its alloy material, and the contact metal 15 is made of a noble metal or its alloy material. The cross-sectional shape of the clad contact 17 is an isosceles triangle, and a contact metal 15 is provided with the apex angle Z being one corner between the two sides X and Y of the isosceles, and the contact metal 15 has a rounded top surface. Then, base metal 1
6, its outer surface is formed into a straight line, and the angle is in the range of 65° to 115°. Furthermore, as a first example of the specific application of this clad contact, the height is 0.4 mm, the maximum width is 0.6 mm, and the apex angle is set in consideration of material efficiency and weldability with the base metal.
90°, Au-8w/oAg as the contact metal 15.
A clad contact 17 having a thickness of 0.1 mm and provided on a base metal 16 made of Cu-30w/oNi was manufactured. In addition, as a second example, Ag-
A clad contact 17 was manufactured using 50w/oPd and otherwise similar to the first example. The clad contacts of the first and second examples are connected to the second
A comparison was made between a conventional example (1) having the configuration shown in Figure B and a conventional example (2) having the configuration shown in Figure 3A. Conventional example (1) has a core material 8 made of Cu-30w/oNi with a diameter of 0.2φmm and a surface layer 7 made of Au-8w/oAg of 0.1mm.
A clad wire contact 9 was manufactured with a thickness of . Conventional example (2) is Cu−30 with a height of 0.4 mm and a maximum width of 0.6 mm.
A clad contact 12 was manufactured by providing a surface layer 10 made of Au-8w/oAg with a thickness of 0.1 mm on a base material 11 made of w/oNi. Each contact point 17, 9, 12 obtained in this way
was welded to a base material made of phosphor bronze to form the structure shown in FIG. 1, and the variation in contact resistance was measured under the test conditions shown in Table 1. Furthermore, after testing under the test conditions shown in Table 1, a shear test was conducted to measure the welding strength, and the results were 10 to 20 Kg/mm ² in the first example and 3 to 4 Kg/mm 2 in the conventional example (1). mm ² was 10 to 18 Kg/mm ² in conventional example (2).

[Table] As is clear from Fig. 5, the clad contact of the first example according to the present invention quickly dissipates the heat generated when used as a contact for an electronic musical instrument for a long time, compared to the conventionally used contact. Since it is diffused into the base metal through the base metal, the contact resistance is always low and stable. In addition, since the material of the base metal can be selected in consideration of the weldability of the base metal, it is possible to obtain a high and stable welding strength with little variation. The clad contact according to the present invention has an isosceles triangular cross section, and only the portion at the apex angle Z is the contact metal 15. Only there, noble metal or its alloy material is used, and the other portions are made of base metal or its alloy. By using an alloy material, the price can be reduced by using only the necessary amount of expensive precious metal materials for the parts (contacts) that are actually used.
Furthermore, it is possible to select the material for the base metal 16 that is in contact with the base metal and welded, taking into consideration the weldability with the base metal, and therefore the weldability with the base metal is high and stable. What you do is what you get. In addition, by having an isosceles triangular cross section and continuous contact metal in a straight line, the contact area when welding with the base metal is increased, ensuring stability, and reducing the amount of contact that occurs when used as an electrical contact. This is to ensure continuous and constant heat diffusion and to stabilize contact resistance, and also to make it easier to distinguish between the front and back to prevent reverse attachment during welding. The reason why the shape of the apex angle Z is rounded is to take into consideration the contact property due to the wipe contact between the movable contact and the fixed contact, and the angle θ
The reason for setting the angle to be in the range of 65° to 115° is that if it is less than 65°, it will be difficult to quickly release the heat generated when using it as a contact for an electronic musical instrument, and if used for a long time, the contact resistance will increase. This is because the amount of contact metal 15 used becomes large if the angle exceeds 115°. Therefore, at an angle in the above range of 65° to 115°, the heat generated when used as a contact for an electronic musical instrument can be quickly released, and contact resistance can be prevented from increasing when used for a long time. , and the amount of contact metal used can be kept small. Furthermore, if the vertices of the isosceles are shifted, directionality will occur and poor contact will occur, so an isosceles triangular shape is preferable. It is of course possible to implement the clad contact shown in FIG. 4 by adding a projection. As described above, the present invention has excellent advantages, and implementing the present invention has enormous practical value.

[Brief explanation of drawings]

Figure 1 is a front view of contacts for electronic musical instruments, Figure 2A,
Figures 2B and 3A are perspective views of conventional contacts, respectively;
3B is a front view of the contact of FIG. 3A, FIG. 4 is a front view of the clad contact according to the present invention, and FIG. 5 is a diagram showing test results. 1a, 1b...base material, 2a...movable contact, 2b
...Fixed contact, 3... Movable contact, 4... Fixed contact, 5... Board, 6... Solid contact, 7, 10...
... surface layer, 8 ... core material, 9 ... clad wire contact, 11 ... base material, 12 ... clad contact,
14a, 14b... hollow, 13a, 13b, 1
3c... hypotenuse, 15... contact metal, 16... base metal, 17... clad contact.

Claims (1)

[Claims] 1. In a clad contact for an electronic musical instrument in which a contact metal is welded to the top of a base metal, the cross section of the overall shape is an isosceles triangle, and the contact metal is attached to the outer surface of a corner sandwiched between the two sides of the isosceles triangle. continuous in a straight line, the top surface of the contact metal is formed in a rounded shape, and the angle of one corner sandwiched between the two sides of the isosceles is in the range of 65° to 115°. clad contact.