Musical sound generation indicator device

Abstract

To stabilize the sensitivity of the output signal to the pressing force in a musical sound generation instruction device. [Solution] The musical sound generation instruction device 100 includes a printed circuit board 10 having a first electrode 121 and a second electrode 122, a carbon sheet 30 containing PTFE particles with a particle size of 5 μm or less, an insulating spacer 20 that separates the carbon sheet 30 from the printed circuit board, a rubber pad 40 that presses the carbon sheet 30, and a musical sound generation instruction unit 200 that outputs a musical sound generation instruction in response to the pressed carbon sheet 30 coming into contact with the first electrode 121 and the second electrode 122.

Description

Technical Field

[0001] This invention relates to a musical sound generation instruction device such as a pad device.

Background Art

[0002] There is known an electronic musical instrument equipped with a pad, and various percussion instrument sounds such as drum sounds and percussion sounds are produced when the pad is struck by hand or with a stick. In an electronic musical instrument, a musical sound generation instruction such as a percussion instrument sound is output by detecting a striking operation in which a performer strikes the pad surface with a hand or a stick.

[0003] A sensor for detecting the strike on the pad surface is disclosed, for example, in Patent Document 1. In the sensor disclosed in Patent Document 1, a carbon sheet layer as an upper electrode and a carbon pattern layer as a lower electrode are arranged to face each other, and the pad to be struck presses the upper electrode against the lower electrode. At that time, since the pad is elastically deformed by the pressing force, the pattern density of the carbon pattern of the lower electrode that contacts the upper electrode changes from sparse to dense according to the pressing force. Thereby, an output signal corresponding to the pressing force is obtained from the sensor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the technique described in Patent Document 1 mentioned above, an output signal corresponding to the pressing force on the pad can be obtained from the sensor. However, in order to enhance the expressiveness of percussion instrument performance, it is necessary to stabilize the sensitivity of the output signal with respect to the pressing force.

[0006] This invention was made in view of the circumstances described above, and aims to provide a technical means for stabilizing the sensitivity of the sensor's output signal to pressing force. [Means for solving the problem]

[0007] This invention provides a musical sound generation instruction device comprising: a printed circuit board having a first electrode and a second electrode; a carbon sheet containing PTFE particles with a particle size of 5 μm or less; an insulating spacer for separating the carbon sheet from the printed circuit board; a pressing unit for pressing the carbon sheet; and a musical sound generation instruction unit that outputs a musical sound generation instruction in response to the pressed carbon sheet coming into contact with the first electrode and the second electrode. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing the configuration of a pad device, which is one embodiment of the musical tone generation instruction device according to this invention. [Figure 2] This is a plan view of the printed circuit board in the same embodiment. [Figure 3] This is a circuit diagram of the musical tone generation instruction unit in the same embodiment. [Figure 4] This is a cross-sectional view of the pad device. [Figure 5] This is a magnified cross-sectional view of the area near the contact zone between the carbon sheet and the printed circuit board of the pad device. [Figure 6] This figure illustrates the dependence of the resistance value between the first and second electrodes of the pad device on the pressing force. [Figure 7] This figure illustrates the dependence of the output voltage change in the pad device on the pressing force. [Figure 8] This figure shows the relationship between the output voltage change and velocity in the pad device. [Figure 9] This diagram illustrates the relationship between pressing force and velocity in the pad device. [Figure 10] This figure shows the carbon sheet manufacturing process in the same embodiment. [Figure 11] This figure shows the first and second electrodes in another embodiment of this invention. [Figure 12] This figure shows the first and second electrodes in another embodiment of this invention. [Modes for carrying out the invention]

[0009] The embodiments of this invention will be described below with reference to the drawings.

[0010] Figure 1 is a cross-sectional view showing the configuration of a pad device 100, which is one embodiment of the musical tone generation instruction device according to this invention. As shown in Figure 1, the pad device 100 is a device made by laminating a printed circuit board 10, an insulating spacer 20, a carbon sheet 30, and a rubber pad 40. Here, the printed circuit board 10 is a substrate in which a gold-plated pattern 12 is laminated on an insulating substrate 11. The carbon sheet 30 is a sheet made by coating a carbon ink layer 32 onto a flexible film, which is a PET (polyethylene terephthalate) film 31. The carbon ink layer 32 contains PTFE (polytetrafluoroethylene) particles. The carbon ink layer 32 is applied to the PET film 31 by, for example, screen printing. The carbon sheet 30 is laminated on the printed circuit board 10 with the carbon ink layer 32 facing the gold-plated pattern 12 of the printed circuit board 10. The insulating spacer 20 separates the carbon sheet 30 from the printed circuit board 10. The insulating spacer 20 may be a wall-shaped insulating spacer stacked to form the four sides of a rectangle, or it may be a plurality of cylindrical or prismatic insulating spacers. The rubber pad 40 is a pressing part that presses against the carbon sheet 30 when struck by the performer's finger. The pressure from this pressing part causes the carbon sheet 30 to flex, and the carbon ink layer 32 of the carbon sheet 30 comes into contact with the gold-plated pattern 12 of the printed circuit board 10.

[0011] As illustrated in FIG. 2, the gold plating pattern 12 of the printed circuit board 10 includes a first electrode 121 and a second electrode 122. In the illustrated example, the first electrode 121 and the second electrode 122 are each comb-shaped electrodes, and are spaced apart from each other and arranged in a plane on the printed circuit board 10.

[0012] FIG. 2 illustrates a contact area 35 between the carbon sheet 30 on the printed circuit board 10 caused by the impact of the rubber pad 40. Within this contact area 35, the first electrode 121 is connected to the second electrode 122 via the carbon ink layer 32. Therefore, the larger the area of the contact area 35, the lower the resistance value between the first electrode 121 and the second electrode 122.

[0013] The pad device 100 according to this embodiment has a sound generation instruction unit 200 shown in FIG. 3. This sound generation instruction unit 200 includes a sensor circuit 210 and a conversion circuit 220. The sensor circuit 210 and the conversion circuit 220 may be mounted on the printed circuit board 10, or may be mounted on other printed circuit boards.

[0014] The sensor circuit 210 is a circuit formed by connecting a resistor 211 having a predetermined resistance value and a resistor 212 between the first electrode 121 and the second electrode 122 in series between a power supply and a ground. And the intermediate node of the resistors 211 and 212 is the output node of the sensor circuit 210.

[0015] When the rubber pad 40 is struck, as illustrated in FIG. 4, the rubber pad 40 and the carbon sheet 30 are bent by the impact, and the carbon sheet 30 contacts the printed circuit board 10. The area of the contact area 35 of the carbon sheet 30 on the printed circuit board 10 increases according to the pressing force.

[0016] FIG. 5 is an enlarged cross-sectional view of the carbon sheet 30 and the printed circuit board 10 within the contact region 35 of FIG. 4. In the present embodiment, the carbon ink layer 32 of the carbon sheet 30 is filled with PTFE particles 321. Thus, irregularities are formed on the surface of the carbon ink layer 32 that contacts the surface of the printed circuit board 10. In FIG. 5, the convex regions are indicated by reference numeral 351. When the pressing force on the carbon ink layer 32 is increased, these convex regions 351 come into contact sequentially and conduct with the printed circuit board 10, resulting in a smooth change in the resistance value of the carbon ink layer 32.

[0017] In the present embodiment, since the carbon ink layer 32 contains a large number of PTFE particles 321, the change in the resistance value of the carbon ink layer 32 with respect to the change in the pressing force becomes smoother compared to the case where the PTFE particles 321 are not included. Therefore, the dynamic range as a pressing force sensor becomes wider.

[0018] When the contact area between the carbon sheet 30 and the printed circuit board 10 increases according to the pressing force, the resistance value of the resistance 212 between the first electrode 121 and the second electrode 122 decreases. FIG. 6 is a diagram illustrating the dependence of the resistance value of the resistance 212 on the pressing force. As illustrated in FIG. 6, the resistance value of the resistance 212 decreases, drawing a smooth curve bulging downward, in response to the increase in the pressing force.

[0019] In response to this decrease in the resistance value, the voltage of the output node decreases from a predetermined reference voltage (the voltage of the output node when not struck). Hereinafter, for convenience, the amount of decrease of the voltage of this output node from the reference voltage is referred to as the output voltage change amount. FIG. 7 is a diagram illustrating the dependence of the output voltage change amount on the pressing force.

[0020] The conversion circuit 220 is a circuit that outputs a musical tone generation instruction having a velocity corresponding to the amount of change in output voltage. As illustrated in Figure 8, the conversion circuit 220 stores a table that associates the amount of change in output voltage with velocity. The conversion circuit 220 converts the amount of change in output voltage obtained from the output voltage of the sensor circuit 221 into velocity according to this table and outputs a musical tone generation instruction that includes this velocity. Figure 9 is a diagram illustrating the dependence of velocity on pressing force.

[0021] Incidentally, the inventor of this invention noticed that the pad device 100 according to this embodiment has a certain problem. That is, a problem concerning the stability of the sensitivity of the output voltage change amount to the pressing force. Specifically, this problem consists of a first and a second problem. The first problem is that the sensitivity of the output voltage change amount to the pressing force varies depending on the striking position of the rubber pad 40 (i.e., sensitivity variation occurs within the pad). The second problem is that the sensitivity of the output voltage change amount to the pressing force becomes unstable when lightly striking.

[0022] The inventor of this invention investigated the causes of the first and second problems. As a result, the following was estimated to be the cause of the first and second problems: namely, there was variation in the particle size of the PTFE particles contained in the carbon ink layer 32, and this variation was estimated to have reduced the stability of the sensitivity.

[0023] Therefore, the inventor of the present invention repeatedly experimented to solve the above problem, and as a result arrived at the carbon sheet manufacturing process 500 shown in Figure 10. This carbon sheet manufacturing process 500 is the process for manufacturing the carbon sheet 30 shown in Figure 1, and consists of a crushing process 510, a mixing process 520, and a coating process 530.

[0024] In the grinding process 510, the PTFE particles are compressed and sheared by a roll mill to a particle size of 5 μm or less. Specifically, the PTFE particles before grinding are specified to have a particle size of 18 μm, but some particles of about 1 to 20 μm are mixed in. In the grinding process 510, these PTFE particles are ground. After going through this grinding process 510, the particle size of the PTFE particles becomes mainly about 0.1 to 5 μm. However, in reality, some particles of about 20 μm that have not been completely ground will remain mixed in. Nevertheless, the PTFE particles will have a small particle size and little variation.

[0025] In the mixing step 520, the PTFE particles that have gone through the grinding step 510 are mixed with carbon and ink resin in a mixer to produce carbon ink. Then, in the coating step 530, the carbon ink (containing PTFE particles) obtained in the mixing step 520 is screen printed onto the PET film 31 to form a carbon ink layer 32.

[0026] By implementing this carbon sheet manufacturing process 500, the aforementioned problems were resolved. Specifically, the variation in sensitivity of the output voltage change in response to pressing force within the pad was reduced. In addition, the sensitivity of the output voltage change in response to pressing force during light impacts became more stable.

[0027] Although one embodiment of this invention has been described above, other embodiments of this invention are possible. For example, in the above embodiment, comb-shaped first electrodes 121 and second electrodes 122 are provided on the printed circuit board 10, but the shapes of the first and second electrodes are not limited to this. For example, as shown in Figure 11, spaced apart spiral-shaped first electrodes 121a and second electrodes 122a may be provided on the printed circuit board 10. Alternatively, as shown in Figure 12, spaced apart concentric first electrodes 121b and second electrodes 122b may be provided on the printed circuit board 10. [Explanation of Symbols]

[0028] 100...Pad device, 10...Printed circuit board, 11...Insulating substrate, 12...Gold-plated pattern, 20...Insulating spacer, 30...Carbon sheet, 31...PET film, 32...Carbon ink layer, 40...Rubber pad, 321...PTFE particles, 35...Contact area, 351...Convex area, 210...Sensor circuit, 211,212...Resistors, 220...Conversion circuit, 200...Musical sound generation indicator, 121,121a,121b...First electrode, 122,122a,122b...Second electrode.

Claims

1. A printed circuit board having a first electrode and a second electrode, A carbon sheet containing PTFE particles with a particle size of 5 μm or less, An insulating spacer that separates the carbon sheet from the printed circuit board, A pressing section for pressing the carbon sheet, A musical tone generation instruction unit that outputs a musical tone generation instruction in response to the pressed carbon sheet coming into contact with the first electrode and the second electrode, A musical tone generation indicator device having the following features.

2. The first electrode and the second electrode are spaced apart and arranged planarly on the printed circuit board. In response to the pressure applied by the pressing portion, the contact area between the carbon sheet and the printed circuit board increases, and a signal is generated between the first electrode and the second electrode. The musical sound generation instruction device according to claim 1, wherein the musical sound generation instruction unit outputs the musical sound generation instruction based on the signal.

3. The musical sound generation instruction device according to claim 1, wherein the carbon sheet and the insulating spacer are printed in a laminated manner.

4. The musical sound generation instruction device according to claim 3, wherein the carbon sheet is a PET film on which carbon ink has been screen printed.

5. The musical sound generation instruction device according to claim 3, wherein the insulating spacer is screen printed on the printed circuit board.

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