JPH04219794A - Chord vibration detecting device - Google Patents

Abstract

PURPOSE:To completely eliminate noise due to external light and to improve detection accuracy and reliability when an optical sensor is used for detecting chord vibration of an electric guitar and so on. CONSTITUTION:Pairs of light emitting elements 16A to 16F and light receiving elements 17A to 17F are arranged respectively below chords 14A to 14F. And a light receiving element 18 is arranged at a position where reflection light from the chords 14A to 14F is not received. This light receiving element 18 detects intensity of external light. Differential circuits 22A to 22F subtract an output value of the light receiving element 18 from output values of these light receiving elements 17A to 17F to detect chord vibration based on this difference.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a string vibration detection device.
A light emitting element is placed below the strings to illuminate the strings, and
A light-receiving element is arranged to receive reflected light from the strings and output a detection signal that changes according to its intensity, and a light-receiving element for detecting extraneous light is arranged near this light-receiving element to detect the intensity of the extraneous light. By detecting string vibration based on the difference in the output values of these light-receiving elements, the influence of extraneous light is eliminated, the detection accuracy is increased when string vibration is optically detected, and the reliability of detection is improved. It is an enhanced version of

0002

2. Description of the Related Art Conventionally, a string vibration detection device, for example, a device for optically detecting the vibration of strings of a musical instrument, has been developed in Japanese Patent Application Laid-open No. 59
-140497, and U.S. Patent No. 473
The one disclosed in the specification of No. 0530 is known.

The former is a vibration sensor for an object, and an incandescent lamp that illuminates the six strings from the side in the body of the guitar is placed next to the outer strings, and the sensor is placed between the six strings. A converging lens is placed on the side of the opposite string.

[0004] An incandescent lamp emits light onto the strings from a direction approximately perpendicular to the direction in which the strings are strung, and the vibrations of the strings placed within the radiant flux of this light are converted into voltage based on the shadows cast in response to the vibrations. It is something to do.

In the latter device, an infrared radiation element is arranged below each string of the guitar, and two photodiodes are arranged above the string in the string arrangement direction (lateral direction).

[0006] Therefore, the light is illuminated from below the string, the light is received by a pair of photodiodes lined up above the string, and the vibration of the string is detected based on the intensity change of the output signal of each photodiode in response to the vibration of the string. This is to detect.

[0007]

[Problems to be Solved by the Invention] However, such conventional string vibration detection devices have had the following problems.

In the former case, there are six
Since the light strings were arranged side by side, high precision was required in the assembly of the light source and light receiving section. Furthermore, the vibration of the string often deviates from the optically effective optical path, resulting in insufficient reliability of detected values.

On the other hand, in the latter case, a light emitting source and a pair of photodiodes facing the light source must be placed above and below the string, which makes the structure of the entire device complicated. High assembly precision was required.

Furthermore, since all conventional devices use a transmitted light method that utilizes the interruption of the optical path by the string, they are susceptible to the effects of light diffraction, especially for strings with a thin wire diameter on the treble side, and the detection accuracy is still insufficient. It wasn't something.

Furthermore, these devices are susceptible to the influence of extraneous light, such as lighting when performing on a stage or natural light when performing outdoors, resulting in a decrease in detection reliability. For example, if the intensity of external light changes while a piece of music is being played (which may occur frequently outdoors), the accuracy of detecting string vibrations will drop significantly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a string vibration detection device that can detect string vibration with high reliability and accuracy in a plane perpendicular to the string stringing direction. .

[0013]

[Means for Solving the Problems] The present invention provides a string stretched on a support, a light emitting means for illuminating the string, and a light emitting device that receives reflected light from the string and adjusts the intensity of the reflected light according to the intensity of the reflected light. A light receiving means that outputs a changing detection signal; an extraneous light detecting means disposed near the light receiving means and outputting an extraneous light signal that changes according to the intensity of light irradiated from the outside; This is a string vibration detection device including a calculation means for calculating the difference between the output value of the detection signal to be output and the output value of the external light signal.

[0014]

[Operation] In the string vibration detection device according to the present invention, the string is illuminated by the light emitting means, and the light receiving means receives the reflected light from the illuminated string. The light receiving means outputs a detection signal that changes depending on the intensity of the reflected light.

The extraneous light detection means receives extraneous light and outputs an extraneous light signal having a value corresponding to the intensity of the extraneous light. Since this extraneous light detection means is arranged near the light receiving means,
This external light signal indicates the intensity of the external light received by the light receiving means.

[0016] Then, the calculation means obtains a calculated value representing only the intensity of the reflected light from the string by subtracting the output value of this extraneous light signal from the output value of the detection signal of the light receiving means, and based on this calculated value, to detect string vibration. This string vibration can be used, for example, as a musical tone signal.

As a result of the above, the influence of external light can be completely eliminated when detecting string vibrations. Detection accuracy increases and detection reliability also increases.

[0018]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 6 are diagrams for explaining a string vibration detection device according to an embodiment of the present invention.

As shown in FIGS. 1 to 4, the guitar 1
1 body 12 and neck 13 have six strings 14A,
14B, 14C, 14D, 14E, and 14F are stretched in parallel to each other.

An optical pickup (hereinafter referred to as a detection unit) 15 is embedded and fixed in the center of the upper surface of the body 12 for detecting vibrations of the strings 14A to 14F. This detection unit 15 includes six light emitting elements 16A to 16F provided corresponding to each string 14A to 14F,
It is configured to include six light receiving elements 17A to 17F arranged corresponding to these light emitting elements 16A to 16F.

Further, a light receiving element 18 is disposed on the side of the light receiving element 17A in close proximity thereto. This light receiving element 18 is for measuring the intensity of external light,
This constitutes an extraneous light detection means.

These light emitting elements 16A to 16F and light receiving elements 17A to 17F each form a pair to constitute six photoreflectors. Further, these photoreflectors are arranged below each of the strings 14A to 14F, and detect the movement (string vibration) of these strings 14A to 14F. FIG. 3 shows the arrangement positions of these light receiving elements 17A (~17F) and the light receiving element 18.

[0024] Furthermore, these light emitting elements 16A to 16F,
For example, as shown in FIG. 4, the light emitting diodes emit light when supplied with a constant value of current from the constant current circuits 19A to 19F, respectively, and illuminate the strings 14A to 14F. As shown in FIG. 3, the light emitted from the light emitting elements 16A to 16F is reflected by the lower surfaces of the strings 14A to 14F located at a certain distance and enters the light receiving elements 17A to 17F as reflected light, respectively.

These light receiving elements 17A to 17F and 1
8 is formed by, for example, a photodiode. The light from each light emitting element 16A to 16F is transmitted to strings 14A to 14F.
When the light is reflected by the light and enters the light receiving elements 17A to 17F, the light receiving elements 17A to 17F generate a photocurrent proportional to the intensity of this reflected light. Therefore, the intensity of this reflected light varies between the vibrating strings 14A to 14F and each of the light receiving elements 17A to 17F.
It will change based on the distance from 17F.

Furthermore, these light receiving elements 17A to 17F
In addition to the reflected light from the strings 14A to 14F, the external light is also uniformly received (FIG. 3). The light receiving element 18 is arranged so as to receive only external light. Therefore, the photocurrents generated by these light receiving elements 17A to 17F are affected by external light. For example, the broken line x in Figure 6
The output is 0.

The photocurrents I1, I2 to I7 from these light receiving elements 18 and 17A to 17F are as follows.
As shown in FIG. 4, current-voltage conversion circuits 20A to
It is converted to voltage at 20F and 21, and the difference circuit 2
It is input to 2A to 22F. That is, the current-voltage conversion circuit 21 converts the voltage V1 (V1=KI1) into the difference circuit 22.
It is supplied to each of A to 22F. Further, these differential circuits 22A to 22F include current voltage conversion circuits 20A to 2
Each output voltage value V2 (=KI2), V3, V4 from 0F
, V5, V6, and V7 are input. Then, the difference circuits 22A to 22F calculate the difference between these two inputs. For example, the difference circuit 22A performs the calculation of V2-V1, and the difference circuit 22B performs the calculation of V3-V1. Here, the output voltage V1 is the photovoltage generated by the external light, and by calculating the above difference, the intensity of the light reflected by the strings 14A to 14F is measured regardless of the change in the intensity of the external light.
It will be detected.

Furthermore, the output signals of the calculated values (K(I2-I1)) of the difference circuits 22A to 22F are amplified via voltage amplification circuits 23A to 23F, respectively, and outputted to, for example, an external speaker amplifier. .

The light emitting elements 16A to 16F and the light receiving elements 17A to 17F, 18 are each configured to have directivity for emitting and receiving light of a certain intensity within a certain range.

Here, the light receiving elements 17A to 17F are shown in FIG.
, has a detection signal output characteristic (output characteristic with respect to lateral string displacement) as shown in FIG. That is, these light-receiving elements 17A-17F exhibit output characteristics shown by curve x when strings 14A-14F vibrate in the left-right direction. It is assumed that the light receiving elements 17A to 17F detect vibrations of the strings 14A to 14F only in portions where the output value monotonically changes in the graph showing this output characteristic.

On the other hand, the light receiving element 18 does not receive the reflected light due to the vibrations of the strings 14A, so it generates and outputs a photocurrent I1 of a constant value due to external light. The external light that generates this photocurrent I1 is transmitted to each of the light receiving elements 17A to 17A.
17F is also input, so as mentioned above, the curve x
Obtain a graph of 0. In addition, although this external light changes depending on the external environment, by subtracting that of the light receiving element 18 from each output value of these light receiving elements 17A to 17F, the string can be stably detected without being affected by the intensity of the external light. Vibration can be detected.

As configured as above, the string vibration detecting device according to this embodiment has the light receiving element 17A (
~17F) generates a photocurrent I2 (~I7) that changes in response to changes in the left-right vibration of the string 14A (~14F). This photocurrent I2 (-I7) includes a component generated by external light.

The current I2 (~I7) generated in this way
) is converted into a voltage value V2 (~V7) by the current-voltage conversion circuit 20A (~20F), and the difference circuit 22A (~22
F). At this time, the photocurrent I1 generated by the light receiving element 18 is also sent to the difference circuit 22 as a voltage value V1.
It is input to A to 22F. This voltage value V1 indicates the light intensity of the external light at the time of this detection.

[0034] Then, this differential circuit 22A (~22F)
Then subtraction is performed between these output voltages (V2-V1,
V3-V1,...), the difference between them is calculated. As a result, the increase in output value due to external light is uniformly erased by this subtraction. Then, this calculated value (V2-V1,...
) is amplified in the voltage amplification circuit 23A (~23F) and output to, for example, a speaker amplifier (not shown). This vibration is then amplified by a speaker amplifier or the like and produced as a musical tone.

In this manner, the present device can accurately detect string vibrations regardless of the strength of the influence of external light.

Further, in the above embodiment, one light emitting element 16 and one light receiving element 17 are arranged below one string 14.
Since the optical pickup 15, which is a unitized photoreflector consisting of the following, is installed, its installation is simple, and since vibrations can be detected independently for each string, the detection accuracy is also improved.

[0037]

As described above, according to the string vibration detection device according to the present invention, the detection signal does not contain noise, and the reliability of detection is improved. Furthermore, string vibration can be detected accurately even with a small amount of reflected light, making it highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a front view of a guitar equipped with a string vibration detection device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a schematic configuration of an optical pickup (detection unit) of a string vibration detection device according to an embodiment.

FIG. 3 is a cross-sectional view showing the arrangement of light receiving elements according to one embodiment.

FIG. 4 is a block diagram showing part of a circuit of a string vibration detection device according to an embodiment.

FIG. 5 is a graph showing output characteristics of a light receiving element according to an example with respect to transverse vibration of a string.

FIG. 6 is a graph showing output characteristics of a light receiving element according to an embodiment with respect to transverse vibration of a string.

[Explanation of symbols]

12 Body (support body) 14A to 14F String 15 Optical pickup (detection unit) 16A to 16
F Light emitting element (light emitting means) 17A to 17F Light receiving element (light receiving means) 18 Light receiving element (external light detecting means) 22A to 22F Differential circuit (calculating means) 23A to 23
F Voltage amplification circuit (string vibration detection means)

Claims (1)

[Claims] Claim 1: A string stretched on a support, a light emitting means for illuminating the string, and a light receiver for receiving reflected light from the string and outputting a detection signal that changes according to the intensity of the reflected light. an extraneous light detection means disposed near the light receiving means and outputting an extraneous light signal that changes according to the intensity of light irradiated from the outside; and an output value of the detection signal output by the light receiving means. , and arithmetic means for calculating the difference between the output value of the external optical signal and the output value of the external optical signal.