JP3736090B2 - Automatic playing device for keyboard instruments - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic performance device for a keyboard instrument in which a key pressing operation is performed based on predetermined performance data by a solenoid unit including a combination of a solenoid and a plunger.
[0002]
[Prior art]
In recent years, many so-called automatic performance pianos that perform unattended performance by automatically operating a keyboard have been commercially available. In this automatic performance piano, generally, the solenoid unit is disposed opposite to the back end of each key, and the drive current based on performance data recorded on a recording medium such as a floppy disk. Is supplied to the solenoid unit, and the plunger pushes the rotation end of the key to perform a key pressing operation.
[0003]
By the way, in order to perform automatic performance accurately based on performance data, it is necessary to control the speed of the plunger with high precision. As a means for carrying out this, the speed of the plunger is detected, and the plunger is detected according to the detected value. The speed of the sound is appropriately feedback controlled.
[0004]
Conventionally, a magnetic speed sensor is used to detect the speed of the plunger. This is provided so that a rod (column) magnet fixed to a non-magnetic material (such as a stainless steel or aluminum round bar) coaxially extending from the end of the plunger reciprocates in the coil, The speed of the magnet, that is, the plunger is detected from the displacement of the voltage induced in the coil by the magnet.
[0005]
[Problems to be solved by the invention]
In this magnetic type speed sensor, the longer the coil, the more advantageous is that a voltage proportional to the speed is induced and a high-quality speed signal can be obtained. However, when the solenoid unit that drives the plunger and the coil on the speed sensor side are close to each other, both magnetic noises affect each other, and the SN ratio of the speed sensor deteriorates. In order to improve the S / N ratio, a sufficient distance between the solenoid unit on the plunger driving side and the coil on the speed sensor side is sufficient. However, in this case, the plunger and the rod-shaped magnet as described above are naturally used. It was thought that there was a sufficient distance between the two and a non-magnetic material had to be interposed between them.
Further, in the sensor, since the ratio of the internal magnetic change / disturbance magnetic change is proportional to the SN ratio, the sensor coil is as thin as possible, and the smaller the distance between the inner peripheral surface of the sensor coil and the rod-shaped magnet, the smaller the sensor coil is. It was confirmed from many experimental results that the detection accuracy was improved. However, if the non-magnetic material between the plunger and the rod-shaped magnet is greatly extended, there is a risk that the shaft will shift, and in consideration of this, the coil inner diameter must be increased to some extent, resulting in detection accuracy. Will be reduced. In addition, lengthening the non-magnetic material causes an increase in size and complexity of the device itself, which is disadvantageous in terms of cost, and is also unsuitable for mounting on a piano.
[0006]
The present invention has been made in view of the above circumstances, and in detecting the operation speed of the plunger of the key driving solenoid unit with the magnetic type speed sensor, a good SN ratio is obtained, and a small and simple structure is provided. An object of the present invention is to provide an automatic performance device for a keyboard instrument that can realize cost reduction.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is based on a plurality of keys which are arranged in parallel on a shelf board to constitute a keyboard, and are arranged opposite to these keys, based on predetermined performance data. An automatic performance device for a keyboard instrument comprising a key drive unit that performs a key pressing operation and a speed sensor that detects an operation speed of the key drive unit,
The key drive unit includes a solenoid and a plunger that is inserted into the solenoid so as to be movable forward and backward, and that moves forward when a drive current is supplied to the solenoid to actually perform a key pressing operation.
The speed sensor includes a rod-like magnet that extends substantially coaxially with the plunger from one end of the plunger of the key drive unit and is fixed, and the magnet that moves forward and backward, and moves with the plunger. A coil in which a voltage is induced,
A shielding portion is provided between the solenoid of the key driving unit and the coil of the speed sensor to shield both the magnetic flux leaking from the key driving unit and the speed sensor.
According to this configuration, even when the magnetism generated by the drive-side solenoid and the plunger in the key drive unit is relatively strong, the magnetic leakage is shielded by the shielding part, and the magnetic influence on the coil of the speed sensor is suppressed. For this reason, the SN ratio of the speed sensor becomes good, and the detection value of the plunger speed can be obtained with high accuracy.
In addition, although there is a shielding part between them, the distance between the key drive unit and the speed sensor can be significantly reduced as compared with the prior art, so that the apparatus can be made compact and the cost can be reduced accordingly.
[0008]
According to a second aspect of the present invention, in the above configuration, a speed sensor side shielding portion that covers the coil of the speed sensor and shields magnetic flux leaking from the speed sensor is provided.
With this configuration, the magnetic field of the key drive unit or other disturbing magnetic field is shielded by the speed sensor side shielding portion, so that the effect of suppressing the magnetic influence on the speed sensor is further promoted, and the accuracy of the detected value of the plunger speed is improved. Figured.
[0009]
Furthermore, in the invention described in claim 3, in the above configuration, the plunger of the key driving unit and the magnet of the speed sensor are directly connected.
Thereby, rattling of the magnet during operation of the plunger is prevented. Further, it is possible to improve the coaxiality between the key driving plunger and the magnet of the speed sensor, and the inner diameter of the coil on the speed sensor side can be reduced to make the distance from the magnet as small as possible. Therefore, the detection accuracy of the speed sensor can be further improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A. Configuration of one embodiment Fig. 1 shows a portion of an automatic performance device P for an acoustic piano according to this embodiment. Reference numeral 1 in FIG. 1 denotes a key, and the performer performs by pressing the front end of the right side of the key 1 in the drawing. The key 1 is rotatably supported on the shelf board 2 via a balance pin (not shown). In such a state, the plurality of keys 1 are juxtaposed in the left-right direction, which is the front / back direction of the drawing, to form a keyboard.
[0011]
Above the rear end of the key 1, a string (not shown) extending horizontally in the left-right direction is stretched corresponding to the key 1. Between this string and the key 1, a known hammer action mechanism for hitting the string by the operation of the key 1 is provided.
[0012]
A storage hole 2 a extending in the left-right direction is formed in a lower portion of the rear end portion of the key 1 in the shelf plate 2, and the automatic performance device P including the key drive unit 3 for each key 1 in the storage hole 2 a. Is stored. The automatic performance device P is supported by a rectangular parallelepiped frame 4 which is screwed to the lower surface of the shelf 2 via stays 5a and 5b. In this state, the key driving units 3 are alternately arranged in a staggered manner in the front-rear direction in the left-right direction so as to be opposed to the lower surface of the rear end portion of each key 1.
[0013]
FIG. 2 shows details of the automatic performance device P, in which the reference numeral 10 denotes a main yoke. The main yoke 10 has a rectangular cross section, and an extended portion 10 a at the lower end of the rear end is screwed to the frame 4. A shield cover 11 having a U-shaped cross section is fixed to the lower surface of the main yoke 10 so that the opening is closed by the lower surface of the main yoke 10. A partition plate 12 is provided inside the shield cover 11 to partition the interior up and down. The main yoke 10 and the partition plate 12 in the shield cover 11 form three shielding parts, that is, an upper magnetic shielding part 13, an intermediate magnetic shielding part 14, and a lower magnetic shielding part (speed sensor side shielding part) 15 in the vertical direction. Yes. In addition, the main yoke 10, the partition plate 12, and the shield cover 11 which comprise each shielding part 13,14,15 are made of soft magnetic bodies, such as iron.
[0014]
A bobbin 20 constituting the key drive unit 3 is accommodated over the upper magnetic shield part 13, the intermediate magnetic shield part 14 and the lower magnetic shield part 15. The bobbin 20 passes through the upper and lower through holes 21a and 21b formed in the bottom plate portion 10a of the main yoke 10 and the partition plate 12 with the axial center along the vertical direction. The bobbin 20 passes through the upper through hole 21a from the upper magnetic shield part 13 and engages with the large diameter part 22 existing in the intermediate magnetic shield part 14 and the lower end part of the large diameter part 22 so as to engage with the lower through hole 21b. And a small-diameter portion 23 existing in the lower magnetic shielding portion 15 so as to be separable. The small-diameter portion 23 has an elastic engagement claw 25 formed on the upper end flange portion 24 that is elastically detachable and coaxially engaged with an engagement hole 26 formed in the lower end portion of the large-diameter portion 22. Has been.
[0015]
An upper bobbin portion 30 is formed on the large-diameter portion 22 of the bobbin 20 in the upper magnetic shielding portion 13 by a flange portion 30a formed vertically, and a coil 31 is wound around the trunk portion 30b. A solenoid 32 is constituted by the coil 31.
[0016]
A plunger 40 is fitted into the large diameter portion 22 of the bobbin 20. The plunger 40 includes an iron plunger barrel 41 slidably fitted into the large diameter portion 22 from the upper magnetic shield 13 to the intermediate magnetic shield 14, and a rod 42 at the upper end of the plunger barrel 41. And a plunger head 43 that protrudes to the outside. A cushion 44 is fixed to the lower surface of the plunger head 43 so as to cushionly contact the upper surface of the main yoke 10. The cushion 44 is made of a flexible material such as felt, and the plunger head 43 is made of an elastic material such as rubber. The plunger 40 and the solenoid 32 constitute a key drive unit 3.
[0017]
According to this key drive unit 3, when a drive current is supplied to the coil 31 and a voltage is applied, the plunger 40 is moved up by the action of the magnetic field, and the plunger head 43 pushes up the rear end of the key 1. A key is pressed and an automatic performance is made. The drive current is supplied to the coil 31 based on pre-recorded performance data, which is output from control means such as a microcomputer (not shown).
[0018]
Now, an upper end portion of a thin cylindrical magnet bar 50 is coaxially caulked and fixed to the lower axis of the plunger barrel 41. The magnet bar 50 extends downward and is inserted into the small diameter part 23 of the bobbin 20, and a slight gap is secured between the magnet bar 50 and the inner peripheral surface of the small diameter part 23. A lower bobbin portion 60 is formed on the small diameter portion 23 of the bobbin 20 in the lower magnetic shielding portion 15 by a flange portion 60a formed vertically, and a coil 61 is wound around the body portion 60b. The coil 61 and the magnet bar 50 constitute a speed sensor 62 that detects the operating speed of the plunger 40.
[0019]
According to this speed sensor 62, when an automatic performance is performed by the operation of the plunger 40 as described above, the magnet bar 50 is also moved up integrally with the plunger 40. When the magnet bar 50 is operated in this way, an induced voltage is applied to the coil 61. And the operating speed of the magnet bar 50, that is, the plunger 40 is detected from the displacement of the voltage. Then, according to the detected value, the control means (not shown) controls the voltage of the drive current supplied to the coil 31 of the key drive unit 3 to make the operation speed of the plunger 40 appropriate, that is, feedback control.
[0020]
B. Action <br/> then one embodiment, the operation of the automatic performance apparatus according to the embodiment.
When a performance signal based on the performance data is supplied as a drive current to the coil 31 of the key drive unit 3 corresponding to the key to be depressed, the plunger 40 moves upward and the plunger head 43 pushes up the rear end of the key 1, A key is pressed. As the performance signal stops, the magnetic field of the key drive unit 3 disappears, the plunger 40 moves naturally, and the key 1 returns to the rest position. The upward movement speed of the plunger 40 is detected by the speed sensor 62, and the voltage of the drive current supplied to the coil 31 of the key drive unit 3 is appropriately feedback controlled according to the detected value.
[0021]
FIG. 3 shows an equivalent circuit of the key drive unit 3 and the speed sensor 62 connected thereto, and FIG. 5 is a schematic diagram corresponding to FIG. In these drawings, loop A is a magnetic loop guided by the upper magnetic shield 13 forming a magnetic path, and loop B is a magnetic loop guided by the intermediate magnetic shield 14 forming a magnetic path. Loop C is a magnetic loop that is guided when the lower magnetic shield 13 forms a magnetic path.
[0022]
Further, during the automatic performance by the key drive unit 3, the solenoid 32 of the key drive unit 3 generates a strong magnetic field, so that the magnetic flux from the upper magnetic shield 13 through the plunger body 41, Furthermore, it leaks out to the lower magnetic shielding part 15 side. That is, the magnetic field generated by the solenoid 32 of the key drive unit 3 forms not only the loop A but also the magnetic loop D and the magnetic loop E in parallel with the loop A. Of these magnetic loops, the magnetic loop E is a cause of noise for the speed sensor 62.
[0023]
However, comparing the number of magnetic fluxes passing through each of the loops A, D, and E, the number of magnetic fluxes in the loop A is much larger than the number of magnetic fluxes in the loop D, and the number of magnetic fluxes in the loop D is larger than the number of magnetic fluxes in the loop E. Is much bigger. In the shield cover 11, the upper magnetic shield part 13, the intermediate magnetic shield part 14, and the lower magnetic shield part 15 are magnetically connected, and the upper magnetic shield part 13 and the intermediate magnetic shield part 14 constitute a closed magnetic circuit. Because. That is, when the loop A passes through the upper magnetic shield part 13 and the loop D passes through the magnetic path formed by the upper magnetic shield part 13 and the intermediate magnetic shield part 14, the magnetic flux of the loop E is greatly weakened, and almost all is shielded. Is done.
[0024]
FIG. 4 shows the speed detection principle of the speed sensor 62. In FIG. 4, the magnetic flux generated by the magnet bar 50 is schematically shown by a two-dot chain line. When a drive current is supplied to the solenoid 32 of the key drive unit 3 and the plunger 40 operates at a speed v (m / s) together with the magnet bar 50 integrated with the solenoid 40, the coil 61 is given by the equation 1 below. , V is proportional to Vs (Volt).
Vs = α · v · (dΦ / dt) · N (Formula 1)
Here, α is a proportionality constant. Φ is the number of magnetic fluxes that intersect with the coil 61 among the magnetic fluxes generated by the magnet bar 50. dΦ / dt is the rate of change of the magnetic flux number Φ accompanying the operation of the magnet bar 50. N is the number of turns of the coil 61. This induced voltage Vs is originally a value that should be detected by the coil 61.
[0025]
However, not only the magnetic flux generated by the magnet bar 50 but also the magnetic flux generated by the magnetic field generated by the solenoid 32 of the key drive unit 3 (indicated by the magnetic loop E in FIGS. 3 and 5) affects the speed sensor 62. This is the reason for the noise described above. The noise voltage Vn (Volt) is given by Equation 2.
Vn = β · (dΦ ′ / dt) · N (Formula 2)
Here, β is a proportionality constant. Φ ′ is the number of magnetic fluxes that intersect with the coil 61 among the magnetic fluxes generated by the solenoid 32. dΦ ′ / dt is the rate of change of the number of magnetic fluxes Φ ′ accompanying the operation of the plunger 40.
[0026]
Noise due to the magnetic flux indicated by the loop E is extremely reduced by the shielding effect. Further, the leakage magnetic flux generated from the speed sensor 62 side is also shielded by the intermediate magnetic shielding unit 14, so that the leakage magnetic flux does not affect the key drive unit 3 side. As described above, the speed sensor 62 and the key drive unit 3 are almost magnetically independent, and extremely little magnetic noise is given to each other. Furthermore, since the lower magnetic shielding unit 15 shields a disturbing magnetic flux in addition to the magnetic flux leaking from the key drive unit 3, the effect of suppressing the magnetic influence on the speed sensor 62 is further promoted. As a result, the SN ratio of the induced voltage from the speed sensor 62 becomes good, and the detection accuracy of the operation speed of the plunger 40 is improved.
[0027]
The magnet bar 50 is a ferromagnetic material and seems to have a low magnetic impedance. However, since the internal impedance is actually high, the magnetic flux flowing through the loop C shown in FIG. 3 is small, and the magnetic flux in the loop C is key-driven. The operation of unit 3 is not affected. In order to increase the internal impedance of the magnet bar 50, it is preferable to increase the distance between the magnet bar 50 and the shield cover 11.
In addition, since the internal impedance of the magnet bar 50 is high and the magnet bar 50 is disposed on the side opposite to the traveling direction of the plunger 40, the leakage magnetic flux passing through the loop E is reduced. If the magnetic rod 50 is directly connected to a certain plunger 40, it is possible to change the common sense that was impossible to use.
[0028]
In addition, although the intermediate magnetic shielding part 14 is interposed, the distance between the key drive unit 3 and the speed sensor 62 can be significantly reduced as compared with the prior art, so that the apparatus can be made compact and the associated cost can be reduced. . In addition, since the magnet bar 50 can be directly connected to the plunger 40, the inclination of the magnet bar 50 due to an attachment error or the like can be reduced, and a coaxial arrangement can be realized with high accuracy. For this reason, the backlash of the magnetic rod 50 during operation can be extremely reduced, and the gap with the inner peripheral surface of the lower bobbin portion 60 around which the coil 61 is wound can be minimized, thereby greatly improving the detection accuracy. Figured.
[0029]
C. Modified example The above embodiment is an example in which the present invention is applied to an acoustic piano. However, the present invention is not limited thereto, and the present invention can be applied to any musical instrument as long as it has a keyboard. For example, the present invention may be applied to natural musical instruments such as harpsichords and organs, or electronic keyboard musical instruments that generate musical sounds electronically.
[0030]
【The invention's effect】
According to the present invention, the shield for shielding both the magnetic flux leaking from the key drive unit and the speed sensor is provided between the solenoid of the key drive unit and the coil of the speed sensor of the plunger of the key drive unit. The leakage magnetic flux is shielded by the shielding part, so that the magnetic influence on the coil of the speed sensor is suppressed. As a result, the SN ratio of the speed sensor becomes good and the plunger speed can be detected with high accuracy.
In addition, by providing a speed sensor side shield that covers the speed sensor coil and shields the magnetic flux leaking from the speed sensor, the key drive unit or other disturbing magnetic flux is shielded by the speed sensor side shield. Further, the effect of suppressing the magnetic influence on the speed sensor is further promoted.
Furthermore, the direct connection between the plunger of the key drive unit and the magnet of the speed sensor can improve the coaxiality of both and suppress the rattling of the magnet. Thereby, the speed detection accuracy can be further improved.
[Brief description of the drawings]
FIG. 1 is a side view showing a state in which an automatic performance device according to an embodiment of the present invention is incorporated in a piano.
FIG. 2 is a cross-sectional view of an automatic performance device according to an embodiment of the present invention.
FIG. 3 is an equivalent circuit of a lock driving unit and a speed sensor connected thereto according to an embodiment of the present invention.
FIG. 4 is a schematic diagram showing a speed detection principle of a speed sensor according to an embodiment of the present invention.
FIG. 5 is a schematic diagram showing a leakage magnetic flux of a lock driving unit and a speed sensor connected thereto according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Key, 2 ... Shelf board, 3 ... Key drive unit, 14 ... Intermediate magnetic shielding part, 15 ... Lower magnetic shielding part (speed sensor side shielding part), 32 ... Solenoid, 40 ... Plunger,
50: Magnet bar, 61: Coil of speed sensor, 62: Speed sensor, P: Automatic performance device.

Claims (3)

A plurality of keys that are rotatably arranged on the shelf plate and constitute a keyboard;
A key driving unit that is arranged opposite to these keys and performs a key pressing operation based on predetermined performance data;
An automatic performance device for a keyboard instrument comprising a speed sensor for detecting the operation speed of the key drive unit,
The key drive unit includes a solenoid and a plunger that is inserted into the solenoid so as to be movable forward and backward, and that moves forward when a drive current is supplied to the solenoid to actually perform a key pressing operation.
The speed sensor includes a rod-like magnet that extends substantially coaxially with the plunger from one end of the plunger of the key drive unit and is fixed, and the magnet that moves forward and backward, and moves with the plunger. A coil in which a voltage is induced,
A keyboard having a shielding portion for shielding both magnetic flux leaking from the key driving unit and the speed sensor between the solenoid of the key driving unit and the coil of the speed sensor. Automatic performance device for musical instruments. The automatic performance device for a keyboard instrument according to claim 1, further comprising a speed sensor side shielding portion that covers the coil of the speed sensor and shields magnetic flux leaking from the speed sensor. The keyboard musical instrument automatic performance device according to claim 1 or 2, wherein the plunger of the key drive unit and the magnet of the speed sensor are directly connected.

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