CN103093803A - Recording system of piano - Google Patents

Abstract

The invention discloses a piano recording system. The main control box and the sensor guide rail of the recording system are provided with a sensor interface and a USB interface on the main control box, and the sensor guide rail is connected with the sensor interface on the main control box through a ribbon cable. The recording system senses and distinguishes different notes and note expressiveness data through the photoelectric sensor installed under the acoustic piano keyboard, and records the process of capturing different notes and note expressiveness data and stores them to the USB connection in the device. The system has the advantages of simple structure, convenient installation of photoelectric sensors and low cost, and is suitable for various types of pianos.

Description

A Piano Recording System

technical field

The invention relates to the technical field of recording, in particular to a piano recording system.

Background technique

The piano is the king of musical instruments. With the development of electronic technology, especially the widespread application of microcomputers, the piano not only maintains the original traditional advantages, but also endows it with many functions, so as to meet the multi-level needs of people's appreciation, practice, and teaching. .

There are many methods for detecting the movement of a key and the speed of a key, and there are other methods of capturing the expressiveness data of the keyboard notes of a certain musical instrument. These methods are realized by means of a mechanical switch structure. The method of using mechanical sensing has many obvious disadvantages, for example, there is no change in sensing, and the control after touching the key is unpredictable. In addition, this type of switch will affect the feel of the keys when playing, and the installation is also time-consuming, requiring very complicated vertical and horizontal adjustments.

The present invention just aims to solve the above-mentioned limitations caused by the mechanical switch, and provides a piano recording system with simple structure, convenient installation and low cost.

Contents of the invention

Aiming at the above-mentioned defects in the prior art, the present invention provides a piano recording system, which senses and distinguishes different notes and expressive force data of the notes through a photoelectric sensor installed under the acoustic piano keyboard, and captures The process of obtaining different notes and note expressiveness data is recorded and stored on the USB connected device. The system has simple structure, convenient installation of photoelectric sensors, low cost and is suitable for various types of pianos.

For reaching above-mentioned purpose, the present invention takes following scheme:

A piano recording system, the recording system includes a main control box and a sensor guide rail, the main control box is provided with a sensor interface and a USB interface, and the sensor guide rail is connected to the sensor interface on the main control box through a ribbon cable , characterized by:

There are 4 PCB circuit boards installed on the sensor guide rail, and each PCB circuit board has 22 photoelectric sensors. Each PCB circuit board is connected by a flexible cable. Consisting of a light-emitting diode and a phototransistor, an optical sensor is installed under each key, and the PCB circuit board can slide on the sensor guide rail and be fixed on the sensor guide rail by fixing screws;

The main control box is connected with a computer installed with a recording software system through a USB interface, and the computer outputs data.

Preferably, the main control box includes a microprocessor with an analog/digital conversion ADC function, and each output voltage data sensed from the photoelectric sensor will be transmitted to the analog/digital conversion ADC on the microprocessor through the sensor interface The output voltage of the photoelectric sensor is digitized through analog/digital conversion, and the micro-processing continuously scans each photoelectric sensor installed on the sensor rail to obtain the output voltage data from each photoelectric sensor.

The invention provides users with a perfect recording tool for recording wonderful performances. With the help of highly sensitive optical sensors, the system accurately captures the playing process, accurately records every moment of performance, the speed of the keys, the maintenance of the pedals, and every subtle movement and change. Every subtle change, such as the weight and rotation speed of the keys and the precise measurement of the pedal sustain, is recorded one by one, just like the wonderful performance of a pianist. The function of automatically converting MIDI formats allows users to save them in any computer or other storage as they wish.

Description of drawings

Fig. 1 is the schematic diagram that optical sensor guide rail is installed in the piano recording system of the present invention;

Fig. 2 is the hardware connection schematic diagram of piano recording system of the present invention;

Fig. 3 is the output voltage schematic diagram of the photoelectric sensor used in the piano recording system;

Fig. 4 is a schematic diagram of the output voltage peak of the photoelectric sensor when a piano key is struck;

Fig. 5 is the measurement data of the key spacing of different brands of pianos measured by the photoelectric sensor.

Detailed ways

Embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 shows the schematic diagram of optical sensor guide rail installation in the piano recording system of the present invention, wherein comprises key 101, photoelectric sensor 102, PCB circuit board 103, sensor guide rail 104, flexible cable 105 and PCB circuit board are fixed screw 106.

The system uses photoelectric sensors to capture data on the movement and movement speed of the keys contained in the music data. An optical sensor is installed under each key of the piano keyboard. A photoelectric sensor corresponds to a key. The optical sensor is an electronic component composed of a light-emitting diode and a phototransistor. Light, the emitted light is reflected back when it encounters the bottom surface of the key, the reflected light will be detected, and the proportional light will be converted into the voltage output by the phototransistor, and the light sensor will be represented by the voltage output by the phototransistor distance from the bottom of the key.

The photoelectric sensors 102 are mounted on PCB circuit boards 103 , and each PCB circuit board 103 has 22 photoelectric sensors 102 . Each photosensor consists of a light-emitting diode and a phototransistor facing upward. The PCB circuit board 103 containing 22 photoelectric sensors 102 is installed in the sensor guide rail 104. Since different piano keyboards are different, the distance between the keys is also different, so by horizontally adjusting the position of the PCB circuit board 103, it can be convenient. The position of the photoelectric sensor 102 is adjusted horizontally. The keyboard of an ordinary piano is composed of black keys and white keys totaling 88 keys (a few pianos only have 85 keys), of which 36 are black keys and 52 are white keys. The sensor rail 104 is composed of 4 PCB circuit boards 103, It is ensured that an optical sensor is installed under each key of the piano keyboard. The sensor guide rail 104 is designed as an aluminum guide rail with a length of 1230mm, and the PCB circuit board 103 can move laterally in the guide rail. After the position is determined, the PCB circuit board 103 can be fixed by fixing screws 106 . Each PCB circuit board 103 is connected by a flexible cable 105, so that each PCB circuit board 103 can be moved independently to achieve the purpose of adjusting and aligning the photoelectric sensor.

Fig. 2 shows a schematic diagram of the hardware connection of the piano recording system of the present invention, which includes a sensor interface 201, a connecting sensor guide rail 202, a main control box 203 and a USB interface 205 connected to a computer system. This recording system comprises main control box 203, the sensor guide rail 104 shown in Fig. The sensor interface 201 is connected.

The main control box 203 includes a micro-processing chip (not shown) with an analog/digital conversion ADC function, and each output voltage data sensed from the photoelectric sensor 102 will be transmitted to the micro-processing chip through the sensor interface 201 On the analog/digital conversion ADC, the output voltage of the photoelectric sensor 102 is digitized through analog/digital conversion, and then compared with the threshold level, such a complete process of key movement, including the expressive force of the key, can be detected , the change trend of the output voltage when the key is pressed and the key is lifted is shown in Figure 3.

The micro-processing continuously scans each photoelectric sensor 102 installed on the sensor guide rail 104 to obtain the output voltage data sent by each photoelectric sensor 102, so that the voltage value of each key can be measured. If the movement rate of the key is known, then the volume of the key can be controlled through the sound engine. Similarly, we can also control some other characteristics of the tone, such as the attack of the piano, the timbre, and so on. The microprocessing in the main control box 203 sends the voltage value data of each key obtained to a computer equipped with a recording software system through the USB interface 205, and the computer completes the analysis and storage of the data. This system uses a compatible musical instrument digital interface MIDI, Data output and stored in the computer is encoded as MIDI signals for further processing.

The initial setting and detection of the sensor guide rail 202 can be realized through the recording software system installed in the computer system. The software system makes it possible to capture data on notes and note expressiveness and adjust them accordingly. The first step of the software system is to run the adjustment function, determine the overall position of each key when it is not played and when it is played, and calculate it. The result is the threshold value of the first level and second level of each key, and then use this value Calculation. These independently generated thresholds allow the system to capture the full range of musical effects, including tremolo, staccato, legato and the lightest playing effects. Next, we mainly introduce the key calibration, automatic left and right alignment check and key test through the software system.

First use the USB cable to connect the main control box 203 with the computer, and connect the sensor guide rail 202 and the main control box 203, run the sensor guide rail (LXR) setting on the computer, and the following prompt message will appear:

- LXR user settings - version 1.04

- Connection to LXR is open

-LXR connected

-LXR version - 1.03 code (SN) 00000000

After the sensor rail LXR is connected successfully, the following menu will appear:

1. Display sensor rail information

2. Calibrate the keys

3. Set the intensity curve

4. Test all keys

5. Record key movement

6. Monitor key value

7. Registration service

It should be noted that during the calibration process, each key is tested and measured according to the same standard. The calibration also verifies whether the induction plate and the track are correctly aligned. In order to ensure the accuracy of the calibration, the calibration should be performed Perform in a dark room or without direct light.

Press the number key "2" to start "Calibrate Keys", at this time, the following prompt message will appear:

Notice:

In the piano room, is the light source a direct light?

1. Yes (yes)

2. No (no)

Press the number key "1" or "2" to confirm whether you are in a direct light source environment, and then the following prompt message will appear:

Calibrating the factory key position, please wait

Key Movement Calibration

please press the first key

The operator presses each key sequentially from left 1 to right 88, and can only press one key at a time, and needs to keep the key at a lower position after pressing until a "short beep" is heard from the computer . The system displays content information about the calibrated key depth (in μm) and ghosting level on each key. The depth of a typical key should be between 5000-10000μm, such as the information shown below:

>Accepted first key depth is 06573μm Ghost level L00000R00304

The keys have been calibrated

please press the second key

By analogy, the calibration of 88 keys is completed. After the last segment of keys is calibrated (every 22 keys as a segment), the alignment information such as the percentage of left and right alignment and a chart will be displayed. If not aligned correctly, the computer will display a warning and sound. For example, when all PCB circuit boards 103 are properly aligned, the following information is displayed:

Symmetry of the 1st keyboard segment: ....*|.....(-4%)

Symmetry of the 2nd keyboard segment: .....*.....(0%)

Symmetry of the 3rd keyboard segment: .....*.....(0%)

Symmetry of the 4th keyboard segment: .....*....(2%)

If the leftmost board is too far to the left, the message displays:

Symmetry of the 1st keyboard segment: ..*...|.....(-56%)

The sensor board for piece 1 (from 1st to 22nd keys) is not properly aligned and should be shifted to the right

Symmetry of the 2nd keyboard segment: ...*..|.....(-36%)

Symmetry of the 3rd keyboard segment: ....*.|.....(-19%)

Symmetry of the 4th keyboard segment: ....*|.....(-4%)

To test if all key sensors are working properly, start the LXR settings first, then press the number key "4" (test all keys). Then press each key at least once (if the key is detected, the key number and detected velocity will be displayed). If all keys pass the test, the message is displayed:

All keys passed the test OK, the test passed.

During the test, the system will measure the relative movement position of the photoelectric sensor and the key. If the photoelectric sensor circuit board is not aligned correctly (more than 2 mm left and right), the system will display the correction information after calibration, for example, the following information will be displayed:

The 3rd sensor pad (keys 45-66) is out of alignment and should be shifted to the left.

It means that the third photoelectric sensor circuit board needs to be loosened and moved to the left about 2mm. If this prompt appears, the calibration will need to be re-run.

FIG. 4 shows a schematic diagram of the output voltage peak of the photoelectric sensor when a piano key is struck. By measuring the time elapsed between the first and second threshold levels, the velocity of the key movement can be calculated. Two threshold levels were chosen to measure the rising voltage when the key was pressed, we chose these two threshold levels to be approximately 50% and 75% of the key movement. When the key is in motion, these two thresholds can be used to select the active part of the key motion. When the two thresholds of 50% and 75% of the key movement occur, the key is continuously depressed to generate mechanical movement, and the value almost reaching its maximum speed is detected. It can be seen from Fig. 4 that the time when the key is struck and the time when the key is reset can be detected.

One set of threshold voltages is used for all keys, and each key can have its own individual threshold if desired. The key range value can be set at the factory or through automatic calibration, so this value can be stored in the microprocessor chip for further modification. Fig. 5 shows the measurement data of the distance between keys of pianos of different brands, when the recording system is used for pianos of different brands, the parameters can be adjusted according to these data.

The scope of protection of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope and spirit of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalent technologies, the intent of the present invention is also to include these changes and modifications.

Claims (2)

1. piano recording system, this recording system comprises master control box and inductor guide rail, is provided with inductor interface and USB interface on master control box, the inductor guide rail is connected with inductor interface on master control box by a ribbon cable, it is characterized in that:

4 PCB circuit boards are installed on the inductor guide rail, 22 photoelectric sensors are arranged on each PCB circuit board, connect by the retractility winding displacement between each PCB circuit board, each photoelectric sensor is made of heads 1 light emitting diode and 1 phototransistor, an optical sensor all is installed under each key, the PCB circuit board can slide on the inductor guide rail, and is fixed on the inductor guide rail by fixed screw;

Master control box is connected with the computing machine that the recording software system is installed by USB interface, and with the computer export data.

2. the piano recording system described according to claim 1 is characterized in that:

Include the little processing with analog/digital conversion ADC function in master control box, each output voltage data of sensing from photoelectric sensor can be transferred on analog/digital conversion ADC in little processing by the inductor interface, by the output voltage numeralization of analog/digital conversion with photoelectric sensor, little processing is arranged on each photoelectric sensor on the inductor guide rail by continuous scan round, obtains the output voltage data that each photoelectric sensor sends.

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