JP4982689B2 - Key displacement detection device - Google Patents

Description

  The present invention relates to an improvement in a key displacement detection device for use in a keyboard instrument having a plurality of keys.

  A musical instrument having a keyboard portion composed of a plurality of keyboards, particularly a piano, is configured such that a musical tone signal is output when a user performs a key release operation. Conventionally, there have been various techniques for obtaining a key pressing speed and a key displacement amount and reflecting them in a musical tone output when a user presses and releases a key. For example, a device provided with a contact that is turned on in accordance with the amount of key displacement at the bottom of each key, detects the timing at which each contact is turned on, and obtains the key pressing speed based on the detected time difference Has been proposed. In addition, a photo reflector (reflection type photo interrupter) is provided for each key, a detection voltage detected according to the amount of reflected light received by the key is obtained, and the obtained detection voltage is substituted into a preset approximate expression. Thus, a key displacement amount detection device for obtaining the key displacement amount has also been proposed (see, for example, Patent Document 1).

Japanese Patent No. 2727719 (page 2-3, FIG. 6)

  However, in the key displacement detection device as described above, since each key is provided with a photo reflector, the influence of light interference between the photo reflectors is not considered at all, and the detection accuracy is necessarily improved. Absent. Further, in the above-described apparatus, it is not easy to obtain an approximate expression, and if this approximate expression cannot be set accurately, the key displacement amount cannot be obtained accurately. There was a problem that it could not be determined accurately.

  The present invention has been made to solve such a conventional problem, and prevents a reduction in accuracy of detecting a key displacement amount due to optical interference, and makes it possible to accurately calculate a key pressing strength by using this. The purpose is to provide.

In order to achieve the above object, the present invention provides an apparatus for detecting a key displacement amount for a keyboard musical instrument provided with a keyboard portion composed of a plurality of keys.
Light transmitting / receiving means for reflecting light from the light emitting element with a key and outputting a signal corresponding to the intensity of the reflected light from the light receiving element;
Based on an output signal from the light transmitting / receiving means, a key displacement amount detecting means for obtaining a key pressing displacement amount from the reference position;
Light shielding means for preventing light from leaking to the adjacent key side;
When the key displacement amount change starts to become flat during the key depression operation, the key depression speed is obtained based on the key displacement amount data ignoring the key displacement amount data within a preset time from the detection time point. And a key pressing speed calculation means .

  According to the present invention, since the light shielding means prevents light from leaking to the adjacent key side, even if this apparatus is applied to each key, it is possible to prevent mutual light interference. Since the influence of reflection from the adjacent key can also be suppressed, it is possible to prevent the key displacement detection accuracy from being lowered due to optical interference.

  As a light shielding means, a pair of thin rectangular parallelepiped plates are provided so as to face each other in the direction of the key arrangement, and the light emitting element and the light emitting element are disposed between the opposed pair of thin rectangular parallelepiped plates (two rectangular parallelepiped plates). It is preferable that the pre-light-receiving element provided close to this is arranged in a simple manner with good performance.

  According to the present invention, it is possible to prevent the deterioration of the key displacement detection accuracy due to optical interference and to realize an apparatus capable of accurately calculating the key pressing speed using this.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a key displacement amount detection apparatus 1000 according to the best embodiment of the present invention. FIG. 1 is a cross-sectional view in a direction perpendicular to the keyboard arrangement direction, for example, in a mute piano having a keyboard portion having 88 keys. Incidentally, the key board unit is configured by arranging a plurality of keys on the far side from in the foreground of the drawing. The key 5 is configured to be swingable with the balance pin 3 as a fulcrum, and a front pin 2 is provided to ensure this.

  Reference numeral 20 denotes a keystroke mechanism. When the key 5 is depressed, the key striking mechanism 20 works and the hammer 20 rotates in the upward direction of the drawing to strike the string 10. At this time, the tip end of the key is configured to release the stationary control of the damper 8 that has stopped the string 10 by pushing up the protrusion 15 to actuate the crank portion 14 and loosen the tension of the metal wire 12. . Note that the width d shown on the right side in the figure is a parameter referred to as a key pressing depth. When the key is released, the key pressing depth d is “0” (reference position), and as the key pressing operation is performed. The key pressing depth increases (in other words, “d” increases).

  Reference numeral 1 denotes a substrate. A light shielding plate 400 and a sensor unit 100 are provided on the right side of the upper surface of the substrate. FIG. 3B shows a configuration when these are viewed in the direction indicated by the symbol A in FIG. 1, and FIG. 3A is a direction perpendicular to the direction indicated by the symbol A in FIG. It is the block diagram which looked at these by (direction). The LED 410 (light-emitting element) and the phototransistor 420 (light-receiving element) are arranged close to each other, and a thin rectangular parallelepiped light-shielding plate 400 is opposed to the LED 410 and the phototransistor 420 on both sides of the LED 410 (light-emitting element). It is provided. Thus, the light from the LED 410 and the reflected light from a certain key are prevented from leaking to the other key side. That is, a pair of thin rectangular parallelepiped plates are provided so as to face each other in the direction of the key arrangement, and the LED 410 and a photo provided close to the LED 410 are disposed between the opposed pair of thin rectangular parallelepiped plates. A configuration in which the transistor 420 is arranged is employed, and the phototransistor 420 of another (adjacent) adjacent key cannot receive light from the LED 410 or reflected light from the key with respect to a certain key. In addition, the phototransistor 420 paired with a certain key is not affected by the light from the LED 410 with respect to a certain key being reflected on the side and bottom surfaces of the adjacent key.

  FIG. 6 is a diagram showing a cross section of one keyboard 5 in the left-right direction of the drawing. A dotted line indicates a light receiving area of the phototransistor 420, and a one-dot chain line indicates a light emitting area of the LED 410. The horizontal dotted line indicates the light shielding means described below. The upper drawing shows the detection range when the light shielding plate is not provided, and the interrupted drawing is the case where the light shielding plate is of a bowl shape with an upper surface opened. In this case, although the optical interference with other keys can be prevented, the detection range becomes considerably narrow. On the other hand, a pair of light shielding plates 400 at the bottom of the drawing are opposed to each other with the LED 410 and the phototransistor 420 interposed therebetween. In this case, it is possible to prevent optical interference with other keys while securing a detection range that is substantially the same as when the light shielding plate 400 is not used.

  Therefore, according to the present embodiment, the light shielding plates 400 and 400 can prevent light transmitted / received with respect to a certain key from interfering with light transmitted / received with respect to another key. Thus, it is possible to prevent the key displacement detection accuracy from being lowered due to optical interference. In addition, the simple light-shielding mechanism has an advantage that dust and the like can be easily cleaned during maintenance such as piano tuning.

  Next, the control system will be described with reference to FIG. The voltage signal from the phototransistor 420 is converted from analog to digital by the A / D unit 215, and the CPU 200 inputs it. As shown in FIG. 4, the relationship between the key depression depth d and the phototransistor 420 is 1: 1, and the key depression depth d is detected according to this relationship. Further, the CPU 200 includes a timer 220, and operates according to a program recorded in the ROM 205. At this time, the RAM 210 is used as a work area. Further, the CPU 200 is configured to control the sound source 300 so as to emit a required music signal from the speaker 305 and to output a calculation result such as a key pressing speed as required.

  Therefore, normally, the CPU 200 receives the digital signal from the A / D unit 215 and obtains the key depression depth d corresponding thereto, thereby controlling the operation of the keyboard instrument.

  By the way, as a result of diligent research by the present inventors, in the case where the key depression depth d changes with time, a characteristic having a certain characteristic has been grasped. FIG. 5 is an explanatory diagram showing this. FIG. 5A shows the time change of the key pressing depth when the key is pressed with a medium strength, and FIG. 5B shows the key pressing depth when the key is pressed strongly. Further, FIG. 5C shows the time change of the key pressing depth when the key is pressed weakly. As shown in all the drawings, the key press depth does not increase proportionally even though the key is pressed, and there is a flat part, and this flat part does not depend on the key press strength. The time length is about 4 to 5 (msec). Considering this point, in the flat portion, the key pressing depth d is a constant value with respect to time change, and therefore when calculating an accurate key pressing speed, a time corresponding to the flat portion is obtained. It is necessary to deduct. It should be noted that the detection of the start point of the flat portion may be determined when the time change of the key pressing depth becomes smaller than a certain threshold value.

  FIG. 7 is an explanatory diagram when this processing is performed. First, the CPU 200 determines whether or not the flat portion has started in step S700, and when it is determined that the flat portion has started (Yes), the timer 220 is started in step S710. On the other hand, if “No” in step S700, the following processing is not performed. Next, in step S720, the input digital signal is ignored (discarded), and it is determined whether or not the timer 220 is turned off in step S730, that is, whether or not it has timed out. While ignoring data is continued in S720, the data ignoring is terminated in the case of Yes. Then, the key pressing speed can be obtained from the time excluding the time corresponding to the flat portion and the key pressing depth at that time.

  Therefore, the CPU 200 detects when the change in the key displacement amount (that is, the change in the key depression depth) starts to become flat according to the key depression, and the key displacement amount within a preset time from this detection time point. The key pressing speed can be accurately obtained based on the key displacement amount data ignoring the data.

  As described above, the present invention can be applied to a keyboard instrument to provide a suitable device.

It is explanatory drawing of a structure of this apparatus. It is explanatory drawing of a structure of a control system. It is typical explanatory drawing of a light-shielding plate. It is explanatory drawing of the relationship between a key depression depth and a phototransistor output voltage. It is explanatory drawing of operation | movement. It is explanatory drawing of operation | movement. It is explanatory drawing of a timer operation | movement.

Explanation of symbols

1 Substrate
2 Front pin 3 Balance pin 5 Key 8 Damper 10 String 14 Crank part 15 Projection part 20 Keystroke mechanism 100 Sensor part 200 CPU
205 ROM
210 RAM
215 A / D converter 220 Timer 300 Sound source 400 Light-shielding plate 410 LED
420 Phototransistor 1000 Key Displacement Detection Device

Claims (1)

In an apparatus for detecting a key displacement amount for a keyboard musical instrument having a keyboard portion composed of a plurality of keys,
Light transmitting / receiving means for reflecting light from the light emitting element with a key and outputting a signal corresponding to the intensity of the reflected light from the light receiving element;
Based on an output signal from the light transmitting / receiving means, a key displacement amount detecting means for obtaining a key pressing displacement amount from the reference position;
Light shielding means for preventing light from leaking to the adjacent key side;
When the key displacement amount change starts to become flat during the key depression operation, the key depression speed is obtained based on the key displacement amount data ignoring the key displacement amount data within a preset time from the detection time point. A key displacement amount detecting device comprising: a key pressing speed calculating means .

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