Mounting structure of piano keyboard scanning circuit board

Abstract

The utility model relates to the field of musical instruments, in particular to an installation structure of a piano keyboard scanning circuit board, which comprises an optical coupler, a scanning circuit board and a film flat cable, and the scanning circuit board is connected through the optical coupler welded on the surface of the scanning circuit board and the film flat cable. The T section bar is provided with a horizontal body and a vertical body, the horizontal body is provided with a clamping groove, a groove, a plane positioning groove and a plane threaded hole, and the vertical body is provided with a vertical surface positioning groove, a vertical surface threaded hole and a V-shaped groove; the L-shaped section bar is provided with a horizontal body connected with a vertical body of the L-shaped section bar, the vertical body is provided with a vertical waist round hole, and the horizontal body is provided with a plane waist round hole; one side of the scanning circuit board is embedded into a clamping groove, close to the front baffle of the piano keyboard frame, of the horizontal body of the T-shaped section bar, and a row of kidney-shaped round holes are formed in the other side edge of the scanning circuit board. Compared with the prior art, the utility model has the advantages that the T section bar, the scanning circuit board and the optical coupler thereof can be adjusted in a lifting manner; the scanning circuit board can horizontally move left and right or be disassembled; the structure is firmly combined with the bottom plate, front-back adjustment is convenient, and wiring is regular.

Description

Technical Field

[0001] The utility model relates to the field of musical instruments, in particular to an installation structure of a piano keyboard scanning circuit board. Background Art

[0002] Due to the characteristics of easy deformation of wood and the influence of processing accuracy, etc., even the piano keyboards and their keyboard frames of the same brand and model will have slight differences. Although the structures of the piano keyboards and their keyboard frames of different brands and models are basically the same, their sizes will all have differences. Therefore, the scanning circuit board bracket usually installed under the piano keyboard is adjustable to facilitate the adjustment of the position of the scanning circuit board and its optocoupler. Usually, the common fixing method is that the scanning circuit board is embedded between the card slots on both sides of a relatively wide aluminum profile plate, and the bottom of both sides of the aluminum profile plate is supported by springs. The screws passing through both sides of the aluminum profile plate are inserted into the springs and then screwed into the middle plate of the keyboard frame. By screwing the screws on both sides of the aluminum profile plate, the springs can be compressed or released, realizing the lifting adjustment of the positions of the aluminum profile plate, the scanning circuit board, and the optocoupler. Most common piano mute systems are of this structure. The disadvantage of this structure is that adjustment screws need to be installed on both sides of the relatively wide aluminum profile plate, and the number is large, so the adjustment is time-consuming. If the springs are not tightened firmly, resonance noise is likely to occur. Some manufacturers set brackets on both sides of the scanning circuit board and adjust the height of the scanning circuit board by increasing or decreasing the gaskets at the bottom of the brackets. The method is relatively simple and crude. There are also some manufacturers who set the scanning circuit board on the hammer mechanism. When the hammer handle moves, due to the large size differences of various models of hammer mechanisms and the characteristics of precision and vulnerability of the hammer mechanism, and relatively complex maintenance, the method of setting the scanning circuit board on the hammer mechanism is rarely used for quick on-site installation by non-professional factory after-sales. The keyboard matrix scanning circuit technology disclosed in the utility model patent ZL202320769826.9, due to the characteristics of simple circuit components and regular and unified circuit layout, the scanning circuit board is narrow and long without occupying much area. It is suitable for both fine assembly in the factory with the scanning circuit board set on the hammer mechanism and quick installation under the piano keyboard. For such a slender keyboard scanning circuit board about 20 mm wide, it is obviously cumbersome and unnecessary to fix and adjust the height with screws and springs on both sides, and it is also not suitable to support it with brackets on both sides. Content of the Utility Model

[0003] The purpose of the utility model is to provide an installation structure of a piano keyboard scanning circuit board, especially for a narrow and long keyboard scanning circuit board, which is convenient for position adjustment, has a delicate structure, saves materials, has fewer adjustment screws, eliminates the springs, is convenient for quick and reliable installation, is also convenient for pre-assembly as a component, and is flexible for disassembly and maintenance.

[0004] To achieve the above object, the present utility model designs an installation structure for a piano keyboard scanning circuit board, which includes an optocoupler, a scanning circuit board, and a flexible flat cable. The scanning circuit board is connected by soldering the optocoupler on its surface and connecting with the flexible flat cable; a T-shaped profile, which has a horizontal body and a vertical body. Among them, a card slot, a groove, a planar positioning slot, and a planar threaded hole are provided on the horizontal body, and a vertical surface positioning slot, a vertical surface threaded hole, and a V-shaped groove are provided on the vertical body; an L-shaped profile, which has a horizontal body connected to its vertical body, a vertical surface oblong hole is provided on the vertical body, and a planar oblong hole is provided on the horizontal body; one side of the scanning circuit board is embedded in the card slot on the horizontal body of the T-shaped profile near the front baffle of the piano keyboard frame, and a row of oblong holes is provided on the other side of the scanning circuit board. The fastening screws pass through the oblong holes and are fixed in the planar threaded holes on the positioning slot of the horizontal body of the T-shaped profile; the flexible flat cable is laid in the groove of the horizontal body of the T-shaped profile and led out from one end; the L-shaped profile connects the vertical surface oblong hole on its vertical body with the vertical surface threaded hole on the vertical body of the T-shaped profile through a profile fastening screw; self-tapping screws are used to connect the lower part of the horizontal body of the L-shaped profile with the middle plate of the piano through the planar oblong hole.

[0005] Preferably, the scanning circuit board of the present utility model is a long and narrow structure. The flexible flat cable is connected to the bottom circuit of the scanning circuit board. The component surface of the circuit board is welded with reflective optocouplers at intervals along one side edge across both ends of the scanning circuit board. A row of oblong holes is provided on the corresponding other side edge across both ends of the scanning circuit board, and the long axis of the oblong hole is parallel to the side edge of the scanning circuit board.

[0006] Preferably, the upper horizontal body of the T-shaped profile of the present utility model is wider than the scanning circuit board. The card slot on one side edge, the planar positioning slot on the other side edge, and a row of planar threaded holes on the slot across both ends of the T-shaped profile. The positions and spacings of the planar threaded holes correspond to the positions and spacings of a row of oblong holes on the same side edge of the scanning circuit board.

[0007] Preferably, a row of vertical surface threaded holes provided on the lower vertical body of the T-shaped profile of the present utility model is arranged on a vertical surface positioning slot across both ends of the T-shaped profile, and the vertical surface threaded holes are equidistantly arranged.

[0008] Preferably, V-shaped grooves are symmetrically provided on both sides of the lower vertical body of the T-shaped profile of the present utility model. The V-shaped grooves cross both ends of the T-shaped profile and are parallel to the side edge of the profile horizontal body. The distance between the V-shaped grooves and the bottom of the upper horizontal body of the T-shaped profile is 2-3 mm, and the distance from the bottom of the lower vertical body of the T-shaped profile is greater than 13 mm.

[0009] Preferably, a row of vertical surface oblong holes is provided across both ends on the upper vertical body of the L-shaped profile of the present utility model, and a row of planar oblong holes is provided across both ends on the lower horizontal body. The long axes of all oblong holes are perpendicular to the side edge of the L-shaped profile, and the vertical surface oblong holes and the planar oblong holes are arranged at equal distances corresponding to a row of vertical surface threaded holes provided on the lower vertical body of the T-shaped profile.

[0010] Preferably, the distance between the profile fastening screw that passes through the vertical waist-round hole on the upper vertical body of the L-profile and is connected to the threaded hole on the upper vertical surface of the lower vertical body of the T-profile and the middle gear of the keyboard stand is greater than 80 mm.

[0011] Preferably, for the present utility model, the scanning circuit board that is connected to the upper horizontal body of the T-profile and the optocoupler surface-mounted soldering are close to the felt ring in front of the black keys. The top of the optocoupler is slightly lower than the felt ring in front of the black keys, and each optocoupler is aligned with the center of the felt ring in front of one key.

[0012] Preferably, the scanning circuit board, the T-profile or the L-profile that are connected to the upper horizontal body of the T-profile of the present utility model are spliced and combined by one to four sections.

[0013] Compared with the prior art, the advantages of the present utility model are as follows:

[0014] The structure of the present utility model is simple and practical. The profile fastening screw can be directly screwed with a short-handled screwdriver to move up and down in the waist-round hole, driving the lifting and adjustment of the T-profile, the scanning circuit board and its optocoupler. Moreover, by screwing the circuit board fastening screw on the surface of the scanning circuit board, the left and right translation or disassembly of the scanning circuit board can also be realized. Since the self-tapping screw passes through the waist-round hole in the lower horizontal body of the L-profile and is screwed into the middle disc bottom plate of the piano, the structure can be firmly combined and installed with the bottom plate, the front and back adjustment is convenient, and the wiring is regular. Description of the Drawings

[0015] The present utility model will be further described below with reference to the accompanying drawings.

[0016] Figure 1 It is a side view schematic diagram of the structure of the present utility model installed on the middle disc of the piano;

[0017] Figure 2 It is a side view enlarged schematic diagram of the connection between the scanning circuit board of the structure of the present utility model and the T-profile and the L-profile;

[0018] Figure 3 It is a cross-sectional view of the T-profile of the structure of the present utility model;

[0019] Figure 4 It is Figure 3 The right view schematic diagram of the T-profile;

[0020] Figure 5 It is Figure 3 The top view schematic diagram of the T-profile;

[0021] Figure 6 It is a cross-sectional view of the L-profile of the structure of the present utility model;

[0022] Figure 7 It is Figure 6 The side view schematic diagram of the L-profile;

[0023] Figure 8 is Figure 6 a top view schematic diagram of an L-shaped profile;

[0024] Figure 9 is Figure 2 a top view schematic diagram;

[0025] Figure 10 is a side view schematic diagram of a scanning circuit board provided with an FFC connector and a profile notch in an embodiment. Figure 2

[0026] In the figure: 1. T-shaped profile, 2. L-shaped profile, 3. optocoupler, 4. scanning circuit board, 5. circuit board fastening screw, 6. profile fastening screw, 7. self-tapping screw, 8. flexible film cable, 9. reflection pad, 10. black key, 11. white key, 12. middle disc, 13. front baffle, 14. white key felt ring, 15. black key felt ring, 16. keyboard frame connecting bar, 17. middle gear, 18. card slot, 19. groove, 20. plane positioning groove, 21. V-shaped groove, 22. vertical surface positioning groove, 23. vertical surface threaded hole, 24. plane threaded hole, 25. vertical surface waist-shaped hole, 26. plane waist-shaped hole, 27. circuit board waist-shaped hole, 28. socket connector. Specific embodiments

[0027] The present invention will be further described in conjunction with the accompanying drawings. The technology of this structure is easy to understand for professionals. The following embodiments are exemplary and not restrictive, and are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Any replacement or change based on the technical solution and concept of the present invention should be covered within the protection scope of the present invention.

[0028] Figure 1 and Figure 2 are basic structure and installation schematic diagrams of the present invention. The T-shaped profile 1, L-shaped profile 2 and scanning circuit board 4 are combined and connected together, installed under the black key 10 and white key 11 near the front baffle 13 of the keyboard frame. The optocoupler 3 welded to one side of the scanning circuit board 4 is close to the black key felt ring 15, and the flexible film cable 7 connecting the scanning circuit board 4 is on the back of the circuit board.

[0029] Figure 3 、 Figure 4 and Figure 5 ​The diagram shows a T-shaped cross-section of a T-shaped profile 1 composed of an upper horizontal body and a lower vertical body. When implemented, the upper horizontal body can also be tilted about 1, with a lower front and a higher rear, roughly parallel to the bottom surface of the pressed key; a slot 18 is provided on the side of the profile near the front stop 13 of the keyboard frame for horizontally embedding the side of the scanning circuit board 4, and a plane positioning groove 20 is provided parallel to the other side of the upper horizontal body of the profile, which crosses both ends of the T-shaped profile 1, and a row of plane threaded holes 24 are intermittently provided on the groove for screw connection Scanning circuit board 4, a groove 19 is also provided in the middle of the upper horizontal body, which is used to place the film cable 7 connected to the scanning circuit board 4; a vertical surface positioning groove 22 is provided on the vertical body of the lower part of the T-profile 1, which runs through both ends of the T-profile 1, and a row of vertical surface threaded holes 23 are arranged equidistantly on the vertical surface positioning groove 22, which are used to screw the L-profile 2, and the vertical surface positioning groove 22 of the lower vertical body of the T-profile 1 is symmetrically provided with V-shaped grooves 21 on both sides above the vertical surface threaded holes 23, which runs through both ends of the profile and is parallel to the side of the profile. The figure shown is the preferred position and groove type of the plane positioning groove 20 and the vertical surface positioning groove 22 on the T-profile 1 of the embodiment. If necessary, the plane positioning groove 20 and the vertical surface positioning groove 22 can also be set on the reverse side, and the groove type can also be selected in a V-shaped shape. The setting of the plane positioning groove 20 and the vertical surface positioning groove 22 is conducive to the precise positioning of the plane threaded hole 24 and the vertical surface threaded hole 23, and also improves the drilling efficiency.

[0030] Figure 6 , Figure 7 and Figure 8 The diagram shows an L-shaped profile 2 with different lengths of two wings in the cross section. A row of equidistant vertical waisted circular holes 25 is provided on the upper vertical body and runs across both ends, and a row of equidistant flat waisted circular holes 26 is also provided on the lower horizontal body and runs across both ends. The long axes of all the waisted circular holes on the upper vertical body and the lower horizontal body of the L-shaped profile 2 are perpendicular to the side of the profile. If necessary, positioning grooves for convenient drilling can also be provided on the vertical body and the horizontal body of the L-shaped profile 2 respectively.

[0031] exist Figure 9 In the schematic diagram, the side of the horizontal narrow scanning circuit board 4 with the optical coupler 3 welded thereon is embedded in the slot 18 on one side of the upper horizontal body of the T-profile 1, and the other side of the scanning circuit board 4 is connected to the flat threaded hole 24 on the other side of the upper horizontal body of the T-profile 1 by the circuit board fastening screw 5. Since the screw passes through the circuit board waist hole 27, when the circuit board fastening screw 5 is loosened, the scanning circuit board 4 can move in a small range along the long axis direction of the circuit board waist hole 27. This movement adjustment can adapt to the size differences of different piano keyboards. Figure 1 and Figure 2Schematic diagram, the FFC film cable 8 connected to the back of the scanning circuit board 4 is laid in the groove 19 of the upper horizontal body of the T-profile 1 and is led out from one end of the T-profile 1. This structural process not only solves the wiring problem for pre-installed universal components, but also facilitates packaging and carrying and quick installation on the piano. At the same time, the groove 19 also enhances the insulation, isolating the metal profile from the electrical circuit contact of the scanning circuit board 4. The figure also shows the plane waist hole 26 on the L-profile 2 located below the T-profile 1, and the long axis of the waist hole is perpendicular to the side of the profile, which facilitates the proper adjustment of the profile structure toward the piano front block 13 or the middle block 17 during installation.

[0032] In order to adapt to the size differences of piano keyboards of different brands and models and enhance the versatility of the structure of the utility model, the scanning circuit board 4 of the embodiment is preferably a scanning matrix circuit of an 88-key piano keyboard spliced ​​and assembled in three sections, corresponding to the high, middle and low pitch areas of the piano, so that the freedom of movement and adjustment of each section is increased, so that each optical coupler on each section of the scanning circuit board can be more evenly aligned with the center of the front fence of each key. Moreover, after segmentation, the scanning matrix circuit bus is decomposed into each section, so the width of the segmented scanning circuit board 4 is narrower than that of a whole unsegmented one, and the width of the corresponding T-shaped material 1 is also narrow, which is conducive to placing a short-handled screwdriver between the T-shaped material 1 and the piano middle 17 to adjust the height of the T-shaped material 1. However, if the segmentation exceeds four sections, the width is narrowed to a limited extent and is not significant, but the lead-out film wiring and installation work need to be increased, which is not worth the loss. The thin film cable 8 connected to the scanning circuit board 4 can be directly welded on the back of the scanning circuit board 4 with an FPC soft cable, or an FPC / FFC socket connector 28 can be welded on the back of the scanning circuit board 4, and the thin film cable 8 is inserted and laid in the horizontal body groove 19 on the upper part of the T-shaped material 1, such as Figure 10 As shown in the embodiment, two notches are provided on the upper part of the T-profile 1. A 2 mm thick socket connector 28 is welded on the reverse side of each scanning circuit board 4 at each notch position, facing the groove 19. Each socket connector 28 is plugged with a thin film cable 8. The figure shows that a thin film cable 8 at the left notch on the upper part of the T-profile 1 passes through the groove 19 at one end of the notch, bypasses the bottom of the socket connector 28, and enters the groove 19 from the other end of the notch, and is stacked with another thin film cable 8 in the groove 19 and led out through the left port of the T-profile 1. The provision of the socket connector 28 makes it more convenient to install, repair and replace the scanning circuit board 4 and the thin film cable 8 without using an electric soldering iron. The pre-assembly of the profile, circuit board and cable into an integrated component is not only convenient for packaging and carrying, but also shortens the installation time on the piano later.

[0033] Figure 10When processing the notch set on the upper part of the middle T-profile 1, the notch is sawed from the top to the V-shaped groove 21, and the material at the notch is broken due to the force of the V-shaped grooves 21 on both sides, forming the upper notch of the T-profile 1. Similarly, the lower notch of the T-profile 1 can be formed by sawing from the bottom of the T-profile 1 upward to the V-shaped groove 21 and breaking the material at the notch. Figure 10 A larger lower notch is shown in the figure, which is required for crossing the keyboard frame connecting bar 16. Usually, a piano keyboard frame has three keyboard frame connecting bars 16 that longitudinally connect the front rail 13 and the middle rail 17 as one body, and the height is about 10 to 12 mm. Therefore, three corresponding notches must be set at the lower part of the T-profile 1 so that the scanning circuit board 4 can cross the keyboard frame connecting bar 16. The V-grooves symmetrically set on both sides of the lower vertical body of the T-profile 1 are preferably 13 mm from the bottom. The V-grooves 21 at the upper part of the notch leave 2 to 3 mm of residual roots at the bottom of the upper horizontal body of the T-profile 1 as reinforcement ribs to maintain the rigidity of the T-profile 1.

[0034] In order to adapt to keyboard racks of different heights, the cross section of the L-shaped material 2 in the embodiment is an unequal L-shaped, that is, the wing lengths are different, one wing is 15 mm and the other wing is 20 mm, which can be as follows Figure 1 or Figure 2 The short wing is connected to the T-shaped material 1, and the long wing is connected to the piano middle plate 12; it can also be interchanged to connect the long wing to the T-shaped material 1, and the short wing to the piano middle plate 12, so as to increase the height of the scanning circuit board 4. Therefore, the continuous waisted round holes on the two wings of the L-shaped material 2 have the same spacing and corresponding positions. In the embodiment, the length of the T-shaped material 1 and the L-shaped material 2 are preferably 1200 mm, and the spacing between the vertical threaded holes 23 on the vertical surface positioning groove 22 of the lower vertical body of the T-shaped material 1 is 110 mm, and the corresponding spacing between the continuous waisted round holes on the two wings of the L-shaped material 2 is also 110 mm, that is, the spacing between the vertical waisted round holes 25 and the plane waisted round holes 26 is 110 mm, and the distance between the two ends of the L-shaped material 2 and the adjacent vertical waisted round holes 25 or plane waisted round holes 26 is 50 mm, and the distance between the two ends of the T-shaped material 1 and the adjacent vertical threaded holes 23 is also 50 mm.

[0035] Figure 1 , Figure 2 and Figure 10It shows that the profile fastening screw 6 passes through the vertical surface waist circular hole 25 of the upper vertical body of the L-profile 2 and is connected to the corresponding vertical surface threaded hole 23 on the lower vertical body of the T-profile 1. By loosening the profile fastening screw 6, the height of the T-profile 1 and the scanning circuit board 4 can be adjusted, so that each optocoupler 3 is close to the corresponding pressed black key 10 or white key 11 below, and a reflection pad 9 is pasted at the position directly opposite the optocoupler 3 under the keys. This not only prevents the impact between the bottom of the keys and the highest component, the optocoupler 3, on the scanning circuit board 4 during playing, but also shortens the infrared light reflection distance of the optocoupler 3, enabling the optocoupler 3 to work effectively and reliably. Since the entire keyboard in the embodiment is assembled in three sections, the width of the scanning circuit board 4 is only 20.5 mm, and the corresponding width of the T-profile 1 is only 21.5 mm, both of which are extremely narrow, occupying little space, leaving enough distance between the profile fastening screw 6 and the middle gear 17 of the keyboard frame, usually 80-90 mm, suitable for directly screwing the profile fastening screw 6 with a short shank turnip head screwdriver for convenient height adjustment.

Claims

1. An installation structure of a piano keyboard scanning circuit board, characterized in that Including An optocoupler, a scanning circuit board, and a flexible flat cable. The scanning circuit board is welded with the optocoupler on its surface and connected with the flexible flat cable. A T-shaped profile has a horizontal body and a vertical body. The horizontal body is provided with a card slot, a groove, a planar positioning slot, and a planar threaded hole. The vertical body is provided with a vertical surface positioning slot, a vertical surface threaded hole, and a V-shaped groove. An L-shaped profile has a horizontal body connected to its vertical body. The vertical body is provided with a vertical surface oblong hole, and the horizontal body is provided with a planar oblong hole. One side of the scanning circuit board is embedded in the card slot on the horizontal body of the T-shaped profile near the front baffle of the piano keyboard frame. A row of oblong holes is arranged on the other side of the scanning circuit board. The fastening screws pass through the oblong holes and are fixed in the planar threaded holes on the positioning slot of the horizontal body of the T-shaped profile. The flexible flat cable is laid in the groove of the horizontal body of the T-shaped profile and led out from one end. The L-shaped profile connects the vertical surface oblong hole on its vertical body with the vertical surface threaded hole on the vertical body of the T-shaped profile through a profile fastening screw. A self-tapping screw is used to connect the lower part of the horizontal body of the L-shaped profile with the middle plate of the piano through the planar oblong hole.

2. The installation structure of a piano keyboard scanning circuit board according to claim 1, characterized in that The scanning circuit board is of a long and narrow structure. The flexible flat cable is connected to the bottom circuit of the scanning circuit board. The component surface of the circuit board is welded with reflective optocouplers at intervals along one side edge across both ends of the scanning circuit board. A row of oblong holes is arranged on the corresponding other side edge across both ends of the scanning circuit board. The long axis of the oblong hole is parallel to the side edge of the scanning circuit board.

3. The installation structure of a piano keyboard scanning circuit board as described in claim 1, characterized in that The upper horizontal body of the T-shaped profile is wider than the scanning circuit board. The card slot on one side edge, the planar positioning slot on the other side edge, and a row of planar threaded holes on the slot run across both ends of the T-shaped profile. The positions and spacings of the planar threaded holes correspond to the positions and spacings of a row of oblong holes on the same side edge of the scanning circuit board.

4. The installation structure of a piano keyboard scanning circuit board according to claim 1, characterized in that A row of vertical surface threaded holes on the lower vertical body of the T-shaped profile is arranged on a vertical surface positioning slot running across both ends of the T-shaped profile, and the vertical surface threaded holes are equidistantly arranged.

5. The installation structure of a piano keyboard scanning circuit board according to claim 1, characterized in that V-shaped grooves are symmetrically arranged on both sides of the lower vertical body of the T-shaped profile. The V-shaped grooves run across both ends of the T-shaped profile and are parallel to the side edge of the profile horizontal body. The distance between the V-shaped grooves and the bottom of the upper horizontal body of the T-shaped profile is 2 - 3 mm, and the distance from the bottom of the lower vertical body of the T-shaped profile is greater than 13 mm.

6. The installation structure of a piano keyboard scanning circuit board as described in claim 1, characterized in that A row of vertical surface oblong holes runs across both ends on the upper vertical body of the L-shaped profile, and a row of planar oblong holes runs across both ends on the lower horizontal body. The long axes of all the oblong holes are perpendicular to the side edge of the L-shaped profile. The vertical surface oblong holes and the planar oblong holes are arranged at equal distances corresponding to a row of vertical surface threaded holes on the lower vertical body of the T-shaped profile.

7. The installation structure of a piano keyboard scanning circuit board according to claim 1, characterized in that The distance between the profile fastening screw passing through the vertical surface oblong hole on the upper vertical body of the L-shaped profile and connecting the vertical surface threaded hole on the lower vertical body of the T-shaped profile and the middle baffle of the keyboard frame is greater than 80 mm.

8. The installation structure of a piano keyboard scanning circuit board as described in claim 1, characterized in that The scanning circuit board connected to the upper horizontal body of the T-shaped profile and the optocouplers surface-mounted thereon are close to the felt ring in front of the black keys. The top of the optocoupler is slightly lower than the felt ring in front of the black keys, and each optocoupler is aligned with the center of the felt ring in front of one piano key.

9. The mounting structure of a piano keyboard scanning circuit board according to claim 1, characterized in that The scanning circuit board connected to the upper horizontal body of the T-shaped profile, the T-shaped profile, or the L-shaped profile is spliced and combined by one to four sections.

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